top causes of lithium ion field failures - dfr solutions dfr conference... · 2018. 3. 22. · 15...
TRANSCRIPT
Top Causes of Lithium Ion Field Failures
Vidyu Challa PhD
Technical Director
DfR Solutions
2
3
4
ldquoStorage battery is a mechanism for
swindling the public
Just as soon as a man gets working on
the secondary battery it brings out the
capacity for lyingrdquo
4
Thomas Edison
5
ldquoWill all the battery startups claiming a
breakthrough please send me samplesrdquo
5
Elon Musk
6
Disconnect Between Lab and Factory
o University and national labs may be technically right in claiming battery breakthroughs
o These are fundamental material breakthroughs
o LCO LFP NMCNCA cathodes all came out of University labs
o Donrsquot expect them in your smartphone tomorrow
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
3
4
ldquoStorage battery is a mechanism for
swindling the public
Just as soon as a man gets working on
the secondary battery it brings out the
capacity for lyingrdquo
4
Thomas Edison
5
ldquoWill all the battery startups claiming a
breakthrough please send me samplesrdquo
5
Elon Musk
6
Disconnect Between Lab and Factory
o University and national labs may be technically right in claiming battery breakthroughs
o These are fundamental material breakthroughs
o LCO LFP NMCNCA cathodes all came out of University labs
o Donrsquot expect them in your smartphone tomorrow
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
4
ldquoStorage battery is a mechanism for
swindling the public
Just as soon as a man gets working on
the secondary battery it brings out the
capacity for lyingrdquo
4
Thomas Edison
5
ldquoWill all the battery startups claiming a
breakthrough please send me samplesrdquo
5
Elon Musk
6
Disconnect Between Lab and Factory
o University and national labs may be technically right in claiming battery breakthroughs
o These are fundamental material breakthroughs
o LCO LFP NMCNCA cathodes all came out of University labs
o Donrsquot expect them in your smartphone tomorrow
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
5
ldquoWill all the battery startups claiming a
breakthrough please send me samplesrdquo
5
Elon Musk
6
Disconnect Between Lab and Factory
o University and national labs may be technically right in claiming battery breakthroughs
o These are fundamental material breakthroughs
o LCO LFP NMCNCA cathodes all came out of University labs
o Donrsquot expect them in your smartphone tomorrow
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
6
Disconnect Between Lab and Factory
o University and national labs may be technically right in claiming battery breakthroughs
o These are fundamental material breakthroughs
o LCO LFP NMCNCA cathodes all came out of University labs
o Donrsquot expect them in your smartphone tomorrow
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
77
o Battery developmentcommercialization times can be
decades long
o Manufacturing scale up is a big hurdle
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
8
Lithium-Ion is your best option if you
have a rechargeable IOT product
8
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
9
Are Lithium Ion Batteries Inherently Dangerous
o Depends on how you treat them
o We all drive around with a tank of gasoline
o They are ubiquitous
o 4 billion Li-ion cells produced annually
o Prized for their energy density
1 Smart Phone =
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
10
Li-Ion Batteries and Paradigm Shift
o With explosion of IOT applications companies whose core
competency is not batteries are using lithium ion batteries to
build products
o Think back to late 1990s and up until 2010 ndash mostly brand
name batteries Big device manufacturers made significant
investments in battery quality
o Now many smaller players ndash customized pouch cells with
exotic form factors to provide form factor flexibility
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
o Narrow operating window must be respected through-out battery life cycle
o Manufacturing application design battery storage warehousing transportation and use
o Lack of battery quality control application integration issues and proper storage procedures will push batteries outside the operating window
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
12
Risk of Catastrophic Failure
o A laptop battery can pack a
similar amount of energy as a
hand grenade
o Field failures occur at
statistically low rates ndash only 1
to 10 ppm
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
13
Human Side of Catastrophic Failure
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
14
And Therersquos Youtube
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
15
Major Lithium Ion Field Failures
o Field failure rate is 2-15 ppm for most of these companies
Look at the economic impact
Company Units Recalled
(Millions)
Field
Failures
Loss
($)
Product Year
Samsung 25 35 $5B Galaxy Note 7 2016
Swagway amp Others 05 100 Hoverboards 2016
Boeing Entire fleet lt10 $600M Dreamliner 2014
Nokia 46 100 $140M Cell phone battery 2007
Sony 10 20 $400M Laptop Battery 2006
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
16
Field Failure Rate vs Economic Impact
o Field failures occur at statistically low rates ndash only 1 to 10
ppm
o But the economic and business impact of Li Ion failure
rates gt 1 ppm are humungous
o For almost every field failure or energetic event there are
plenty of non-energetic failures that do not make to the
news
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
17
Outlineo Lithium Ion Paradigm Shift
o Field Failure Rate vs Economic Impact
o Battery working mechanism
o Battery Failures
o Samsung 2016 failures ndash Can standards based testing prevent field
failures
o A123 Failures ndash Can battery failures make or break a company
o Relevance of Nail Tests
o New Product Categories E-Cig Case Study
o Common Pitfalls
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
18
Battery Working Mechanism
o Anode negative
electrode cathode
positive electrode
o Lithium ion is an
intercalation battery
(lsquorocking chair mechanismrsquo)
o insert between layers
or in crystal structure
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
o Solid electrolyte interphase (SEI) formed during first few
charging cycles
o SEI can be unstable outside operating window
19
Graphite Anode SEI Organic Electrolyte
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
20
Why did Samsungrsquos 2016
failures happen after
passing safety tests
Disclaimer All field failure data is from information in public domain
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
2121
Battery
Management
System
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
22
Abuse Tests vs Real Life Scenarios
o Majority of standards based testing is focused on abuse
tolerance ndash overcharge crush impact and external short circuit
o Vast majority of field failures happen under normal operating
conditions
o Standards based testing is required but not sufficient to prevent
failures
o Lack of field failures from abuse points to success of standards
o Compliance testing is done on batches of cells It does not prove
out continuous quality
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
23
Real Life Field Failure Cause
o Majority of field failures
o Are related to internal shorts
o Are due to manufacturing defects some are
design related
o Internal shorts are not mitigated by battery
safety systems
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
24
Does Passing a Nail Test Mean
You will survive an Internal
Short
24
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
25
Nail Test Reproducibilityo Test results depend on sharpness of nail nail material whether
the nail fully penetrates the cell etc
o Shallower the depth smaller the contact area and greater the current
density
o Fully penetrated cell can pass the test
Battery State Nail Speed (mmsec)
End of Charge Voltage (EOCV) State of Charge (SOC) 2 4 8 12 16
42 V 95
405 V 85
40 V 79
397 V 74
395 V 71
39 V 62
Nail test at different nail speeds and end of charge voltage (EOCV) for 22 Ah cylindrical cell PassFail
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
26
Nail Test Shortcomingso Nail test ndash huge problems with reproducibility
o No control over the kind of internal short induced (between current collectors
vs active material)
o Magnitude of short (area)
o Nail test vs real life internal short - different timescales
o 200-500 millisecond thermal runaway vs weeks or months
o Nail tests best represent what happens when a nail penetrates a
cell under narrowly defined conditions
o Not propensity for thermal runaway in the field via grown-in internal shorts
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
27
Can a Battery Failure
Make or Break a
Company
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
28
A123 2012 Battery Failures
o 2001 MA startup ndash lithium ion cells for automotive applications
o Sole source supplier for Fiskerrsquos plug in hybrid Karma
o Defective batteries led to recalls bankruptcy filings for both A123 and Fisker
o Mis-calibrated welding machine that created potential for shorts
o Cooling fluid leakage
o Every Fisker Karma had to have the battery replaced 55 million dollar loss
o Company survived and later rebounded
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
29
29
Abuse Manufacturing Defects Cell amp Application Design Handling
Thermal Abuse
Electrical Abuse
Mechanical Abuse
2 90 5 3
bull BMS amp Circuitry safety guidelines
bull Safetystand Tests
Fiel
d F
ailu
re
Mit
igat
ion
Val
Fa
ilure
Cau
ses
Nea
r M
iss
Even
ts
0 50 25 25
Internal Shorts Cell Design
Application design
Storage
Assembly into host device
bull Quality Process Control
bull CT teardownManuf audit
bull Design reviewsbull CT ScansApp
specific testing
bull Process and procedure review
bull Self discharge tests
User
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
30
E-Cig Case Study
New Product Category New Use of
Lithium Ion Batteries
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
31
Product and battery design
o Most use an 18650 design in cylindrical can
o In the event of thermal runaway battery and E-cig behaves like a pipe bomb (weaker structurally at device ends)
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
32
User behavior
o Carrying spare batteries in pocket
o Using alternate chargers ndash mistakenly assuming any USB chargers can be usedo Charging circuitry and BMS have protection optimized for the
application
o Sourcing spare batteries ndash chemistry and manufacturing quality unknown protection circuitry adequacy unknowno Users gravitate to high capacity and high power batteries
o from the internet
o old batteries from laptopstools
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
33
Case Study E-Cig Failures
o Failure rates
o 9 million E-cig users in the US
o 195 incidents of fireexplosion reported in the news between 2009 and 2016
o Statistically low rates but severe and life changing consequences for victims
o Regulatory aspects
o FDA now regulates E-cigs but safety aspects are not addressed
o New UL standard issued in 2017
o Courts have started to hold e-cig makers and supply chain accountable
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
34
New Product Category
Risk Assessment and Mitigation
o Consider user behavior
o Assess battery and product design interactions
o Consider strong warning labels if risk and impact of failure are extremely high
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
35
Common Pitfalls
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
36
Pitfall 1 Deep Discharge Swelling
o Hazard from over discharge is
highly underestimated
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
37
o When a cell goes into deep discharge
copper ions from the negative
electrode current collector dissolve On
recharge copper dendrites can form
o Over discharge can also cause
breakdown of the SEI layer and gas
formation
Image Source Rui Guo1 Languang
Lu1 Minggao Ouyanga1 and Xuning
Feng1 Sci Rep 2016
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
38
Deep Discharge Swelling
o Store at 25 C and at moderate state of charge (lt50
state of charge)
o Obtain self discharge rate curves at different temperatures
o Implement appropriate recharging procedures if extended
storage is necessary
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
39
2 Pouch Deformation from Host Deviceo Deformation of pouch cell from surrounding
components low tolerance or features in
hard case
o Latent mechanical damage to the separator
and electrodes creates the potential for
lithium plating and separator breach
o Charge-discharge cycling of mechanically
damaged cells is not evaluated by standards
o Process and procedure check CT scans of
cells after application use
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
40
3 Not Conducting Cell Quality Assessment
o Negative electrode(anode) overlap positive gt 01
mm (IEEE 16251725)
o Metallic contaminationburrs to be avoided
o No weld defects
o Coating adhesion has to be optimized
Anodes Cathodes
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
41
Closing Thoughts
o System level safety starts with the cell encompasses pack host
device environment and ends with the user
o Recognition that operating limits of the lithium ion battery must be
respected at all costs and through the life cycle of the battery
o Battery safety spans different functions ndash quality product
engineering manufacturing compliance warrantyservice
o Having the right processes and procedures in place
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars
Questions
o Vidyu Challa
o vchalladfrsolutionscom 301-640-5834
o Linkedin httpswwwlinkedincominvidyu-challa-phd-59a93b6
o wwwdfrsolutionscom resources page for battery and other electronic reliability resources and webinars