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Lithium Ion/Polymer

Battery Assembly

Design and Trends

Presented by Brion Munsey

Western Regional Sales Manager

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Cell Types

Safety Circuits

Charging

Storage

Shipping/RoHs

Qualifying Assemblers

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Cell Types: Cobalt based

Manganese (Spinel)

Nickel-Cobalt Manganese

Nickel-Cobalt Aluminum

Polymer

Lithium Iron Phosphate

New Developments: Capacity Improvements

Lower Costs

Hi Drain Cells

Safer Cells

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High energy density - potential for yet higher capacities.

Does not need prolonged priming when new. One

regular charge is all that's needed.

Relatively low self-discharge - self-discharge is less than half that of nickel-based batteries.

Low Maintenance - no periodic discharge is needed; there is no memory.

Specialty cells can provide very high current to

applications such as power tools.

Lithium Ion Advantages

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Requires protection circuit to maintain voltage and current within safe limits.

Can be subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect.

Transportation restrictions - shipment of larger quantities may be subject to regulatory control.

Expensive to manufacture – due to added safety and regulatory requirements.

Not fully mature - metals and chemicals are changing on a continuing basis.

Lithium Ion Limitations

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Lithium Cobalt Oxide LiCoO2

Voltage: 3.7/cell

Pro: High Capacity

Con: Moderate Drain Rate Capability Moderate Safety Moderate Life Span

Applications: Cell Phones, Laptops, Cameras

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Voltage: 3.7/cell

Pro: Safe High Power Long Life

Con: Lower Capacity

Applications: Power Tools, EV, Medical, Hobby

Lithium Manganese Oxide LiMn2O4

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Lithium Iron Phosphate LiFePO4

Voltage: 3.2/cell

Pro: Safe High Power Long Life Large Format Available

Con: Lower Capacity

Applications: Power Tools, EV, Medical, Hobby,

Back Up Power

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Lithium Nickel Manganese Cobalt Oxide

LiNiMnCoO2

Voltage: 3.7/cell

Pro: Safe High Power Long Life

Con: Lower Capacity

Applications: Power Tools, EV, Medical, Hobby

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Voltage: 3.7/cell

Pro: High Capacity High Power Long Life Span

Con: Higher Cost

Not as Safe as LiMn2O4 & LiFePO4

Applications: Portable and EV Smart Grid

Lithium Nickel Cobalt Aluminum Oxide

LiNiCoAlO2

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Pro: High Power Fast Charge (10C) Good Low Temp Performance Long Cycle Life (6000)

Con: Lower Cell Voltage (2.4)

Applications: XEV, Grid, Medical, Military, UPS

Lithium Titanate Li4Ti5O12

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Voltage: 3.7/cell

Pro: Flexible Packaging Thin Low Cost Lightweight

Con: Less Durable Can Swell

Applications: Mobile, Medical, Military, EV

Lithium-Ion Polymer

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Typical Energy Densities of Rechargeable Battery Chemistries

Lithium-cobalt has the highest specific energy Manganese and phosphate are superior

in terms of power and thermal stability and cycle life.

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Energy Density Improvements and Cost Reduction for Lithium Ion

Lithium cells and batteries have made great progress over the last 20 years in terms of gains in energy density and

decreases in cost.

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Series: Up to four cells/groups in series (14.4V to14.8V) standard.

More than four cells custom requiring cell balancing.

Issues with 5S to 10S Cell Strings Cell balancing required

Extra components and custom design increase cost and development time.

FIFO (stock rotation) of cells Important practice

Cells lose capacity permanently if stored too long

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Overcharge Protection

Limit the charge voltage

Over-discharge Protection

Designed to cut off the current path if the battery is discharged below the manufacturer's recommended voltage

Over-current Protection

Discharge is stopped when output terminals are shorted

Resettable on PCBA and one time device as backup

Temperature Sensing

Via Thermistor

Disconnects the charge if the cell temperature approaches 90°C (194°F)

Safety Circuit Features

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Always use a CC/CV charger designed specifically for use with

your particular Li-ion or Li-Poly battery

Lower charge voltage can increase cycle life at the expense of capacity

Charging

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Batteries should be stored at room temperature at about 30%

to 50% of capacity. Batteries should be charged about once a year to prevent over discharge if not being used

Storage

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The life expectancy of batteries depends heavily on how the batteries are used

Different cells models are designed for specific benefits such as high capacity, high power, or long cycle life

Performance

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Testing and Transportation Requirements

All lithium and lithium ion/polymer cells and batteries

must pass the following UN Tests prior to being transported:

Test 1: Altitude Simulation

Test 2: Extreme temperature changes

Test 3: Vibration

Test 4: Shock

Test 5: External Short Circuit

Test 6: Impact

Test 7: Overcharge

Test 8: Forced Discharge

Shipping

All lithium-ion/polymer batteries must be tested and ship in accordance with the rules outlined in U.S. Hazardous Materials Regulations 49 CFR sub section 173.185 for lithium batteries and cells and/or meet the requirements for shipping according to the IATA Dangerous Good Regulations when applicable regardless of lithium content or Watt/Hour rating.

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Packaging, marking, and shipping documentation requirements for shipments of lithium and lithium ion cells and batteries

Boxes must be marked appropriately

Shipments must be accompanied by proper documentation

Boxes must be able to pass drop test (must be certified)

Boxes may not exceed 30 kg gross mass

Shipping

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RoHs

House of Batteries is fully committed to meeting the requirements of the European Union (RoHS) Directive.

The RoHS directive specifically excludes cells & batteries.

Legislation mandates specific recovery (recycling) programs for batteries and battery assemblies. Any potentially harmful waste stream (WEEE) is avoided.

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Inexpensive, poorly designed, and cheaply built batteries are a source of trouble.

Product and corporate reputation is compromised when

problems occur in the field

Public safety is threatened when poorly designed and built batteries malfunction to the point of presenting a hazard

Product returns increase and extra demand is placed on customer service

Many major manufacturers including Sony, Apple, Nikon, and Disney have had recalls on lithium rechargeable batteries due to quality issues

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Qualified Cells: Avoid use of inexpensive, substandard

cells

Is assembler certified by manufacturer?

Safety Circuit:

Avoid use of substandard components on circuit (counterfeit)

Back up with passives

Do not use circuit as primary source of discharge termination

Packaging:

Plastic enclosure best. Careful layout in soft packs can be safe

Soft packs should not be user replaceable

Pack Design Best Practices

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Checklist to Qualify

Assembler:

ISO Certified?

Quality Department?

Large Engineering Staff?

Extensive Test Equipment?

Hazmat Shipper?