brian j. landi - oecd

Nanomaterial approaches to enhance lithium ion batteries Potential Environmental Benefits of Nanotechnology:

Fostering Safe Innovation-Led GrowthJuly 17th, 2009

Brian J. LandiAssistant Professor of Chemical Engineering and Sustainability

NanoPower Research Laboratories (NPRL)Golisano Institute for Sustainability (GIS)

Rochester Institute of [email protected]

mailto:[email protected]

Potential Environmental Benefits of Nanotechnology: Fostering Safe Innovation-Led Growth

Rechargeable Batteries

• Rechargeable batteries, also known as storage batteries, are a continuing strong market, with worldwide sales of $36 billion in 2008. The rechargeable battery market will rise to $51 billion by 2013.

• In the US, lead-acid battery technology continues to head rechargeable battery sales with a rechargeable battery market share of 79% in 2008.

• The portable rechargeable battery market, of which lithium-ion has a 75% share, is the fastest growing segment of the rechargeable battery market, showing world market growth of 20% in 2008.

Recent Economic Trends (source: Aarkstore Enterprise)

http://www.oecd.org/home/0,3305,en_2649_201185_1_1_1_1_1,00.html


Advantages of Lithium Ion

•Higher Energy and Power Density•Higher Cell Voltage (2 to 3X over Ni-X)•High charge rates available •Low Self discharge rate (1-5%/month)•Chemistry is form factor dependent (flexible design)•Life can exceed tens of thousands cycles

Portable Energy Challenge: Energy demand exceeds supply

• Increase Energy Density (carry more)• Fast Recharge (refill often)• Device Energy Efficiency (use wisely)

Advantages of Lithium Ion

→

→

Side note: ZPower has reported that Silver Zinc technology has higher energy density than Li ion



Energy Density vs. Power Density

• Energy (J or Wh) is the ability to do work (currency)

• Power (J/s or W) is the rate energy is consumed (spending)

• Power/Energy ratio relates to battery application

Lithium ion batteries are generallyoptimized either for high energy(e.g. for the consumer laptop orcellphone market where longerruntimes are a premium) or forhigh power (e.g. for the powertool or hybrid vehicle marketwhere brief, high power pulsesare a premium).



Demands for Rechargeable Batteries

Altairnano and A123 Systems have independently developed 2MW power units for demonstration of utility-grade energy storage as a replacement for lead acid batteries.

HEV: P/E = >15 PHEV: P/E = 3-10EV: P/E = <3

Source: US DOE

Consumer Electronics

Automotive

Grid and Renewable Energy Storage

Industry Considerations

-Battery size (energy density)-Number of units

-Cell form factorsfemanagement



Considerations for Vehicles

• Battery Size and Cost (today: $1000+/kWh)

HEV:1-2 kWh, PHEV: 5-15 kWh, EV: 40+ kWh

• Safety – battery abuse from overcharge, physical damage, or high temperature; high voltage (300-400 V) concerns

• Policy Incentives – if economics are only driver, then it directly competes with oil:

Electric vehicle with a $10,000 battery requires oil to exceed $125/barrel to equal 5 year total cost of ownership in a Volkswagen Golf 1.6 driven 15,000 km annually – source: Boston Consulting

• Model for ownership – buy electric vehicle, lease electric vehicle, or battery exchange (better place model)

• Manufacturing and battery design



Battery Manufacturing…for Vehicles

Today…18650 cells

The Tesla Roadster batterypack (53 KWh-375 V) iscomprised of about 680018650 cells; pack has amass of about 450kg.Source: Tesla Motors

In the near future…

Battery design for safety, performance, and end-of-life

• United States: American Recovery and Reinvestment Act of 2009 authorized $2 billion in grants for manufacturers of advanced battery systems and components• Germany: Lithium Ion Battery 2015 $650M for 1M PHEV cars by 2020• Japan: Next Generation Vehicle Battery Program• China: National High Tech R&D Program

Global Investment in Manufacturing

~3.3 Billion cells in 2008


http://www.electrovaya.com/Default.aspx


Solid-Electrolyte Interface (SEI) is a surface filmthat generally establishes between anelectrode and electrolyte and serves as apassivation layer to allow diffusion of Li+ butrestricts additional solvent reduction

Mechanism and Components of Li+

Anode – (negative) – active material, binder, substrate, additives

Cathode – (positive) – active material, binder, substrate, additives

Electrolyte – Lithium salt in mixed carbonate solvents; additives for overcharge, SEI regulation

Separator - porous polyolefin

Components



Active Materials Comparison

Electrode Capacity: set by intrinsic materials properties and method of fabrication (i.e. coating thickness, active material loading, etc.)

Battery voltage: set by anode/cathode materials and is derived from the electrochemical potential difference

Battery Energy Density (Wh): is the product of capacity (Ah) and average voltage (V) -the discharge profile is critical

Li4Ti5O12 has a lithium ion potential of 1.5 V vs. Li/Li+

for intercalation



Li+ Battery Development

There are many possible combinations of active materials for the anode, cathode, and electrolyte that are used in commercial lithium ion batteries – each combination will affect performance (i.e. voltage, energy density, cyclability, etc.)

Source: US DOE

Variation in relative constituents will alter performance and energy density (by mass and volume)

Anode

Cathode

Electrolyte

• Graphite•MCMBs•Li4Ti5O12

• Silicon• Tin• Nanotubes

• LiPF6

• Carbonates• Additives

• Solid Electrolyte• Ionic Liquids•LiBOB, LiTFSI

• Metal Oxides• Iron Phosphate• Mixed Oxides

• High Voltage Phosphates•Layered Oxides



Challenges with Li+ Today

Aluminum

LiCoO250 mm

MCMB

Copper 50 mm

Fabrication &Processing Cell Design &Form Factor Variations in Performance

•Coating Thickness •Binder concentration •Conductive additives •Particle surface area

Reality: Manufacturing Design affects Energy Density, Power Density, Cost, Cyclability, Safety…

Outcome: Some batteries are good for certain applications, others are not…

•Cylindrical vs. Prismatic•Container materials•Safety components



Source: Vukusic and Sambles, 2003

1 mm

Enhancement of light collection on the cornea of a night-flying moth

Imitating Nature

Physical

• Surface area/interfacial energy from

high surface to volume ratio

• van der Waals forces

Nanomaterials can have unique quantum confinement properties that are particle size dependent

Properties of Nanomaterials



Advantages of Nano in Lithium Ion

• Small particle size decreases electron diffusion parameters (benefit: high rate capability; detriment: need for percolation to current collector)

• High surface area allows active material to absorb lithium ions more effectively (benefit: higher capacity; deteriment: increased SEI)

• Small particle size may accommodate crystalline expansion of lattice (benefit: improved cyclability; detriment: lattice crystallinity)

• Nanotubes and nanowires can enhance electrical percolation and mechanical properties by entanglement

Doped LiFePO4 = 165 mAh/g*

Altairnano nano-Li titanateElectrovaya SuperPolymer®

Nanomaterials offer the potential to create a unique lithium ion battery with both high energy and power density



Recent Nanomaterial Research

Capacity >1000 mAh/gDirected growth

Silicon and Germanium Nanowires LiMn2O4 Nanowires

Higher Rate capability over conventional materials

Potential Limitation: conventional slurry on metal current collector



Single Wall Multi-Wall

• High conductivity

• Nanoscale porosity

• Electrochemical and thermal stability

• High tensile strength/Young’s modulus

Carbon Nanotubes

Carbon nanotubes can be envisioned as a rolled up graphene sheet into a seamless cylinder. The role-up vector will determine the so-called ‘chirality’ of the single wall carbon nanotube, which relates to whether the structure will be metallic or semiconducting.

Single Wall

Bundle



Carbon Nanotubes for Li+ batteries

CNTs can be used as a conductive additive material which increases capacity, improves cyclability, enhances rate capability and mechanical toughness due to percolation network

Review Article in the June 2009 Issue

2 CNTs can be fabricated into free-standing electrodes

− Anode – lithium ion storage• Predicted LiC2 = 1116 mAh/g, • 3X improvement over

graphite maximum of LiC6

=372 mAh/g− Active material support for ultra

high capacity semiconductors and electrical percolation pathways

Overview of potential uses

1



Increased specific capacity Zero voltage SOCIncreased DODHigh temperature – no binderComparable C-ratesFlexible GeometriesSemiconductor Support

CNT Advantages

Free-Standing Carbon Nanotubes Electrodes

CNT free-standing electrodes offer a constant capacity as a function of thickness which can dramatically improve the usable electrode capacity in a full battery, particularly in a high power battery design.



5 nm

(a) (b)

100 150 200 250 300

Ram

an I

nte

nsi

ty (

a.u.)

Raman Shift (cm-1

)

1.96 eV

2.54 eV161

181

164

179

(a) (b)

100 150 200 250 300

Ram

an I

nte

nsi

ty (

a.u.)

Raman Shift (cm-1

)

1.96 eV

2.54 eV161

181

164

179

Si-SWCNTs

SWCNTs

MWCNTs

35%50%

145%

75%

Battery Capacity Improvements

CNT free-standing electrodes have the potential to more than double the state-of-the-art battery capacity with proper design and density.



Challenges going forward

• Ongoing technical research is necessary

• Manufacturing/Costs are not available or competitive

• Purification of materials requires technical expertise and energy intensive

• Lack of knowledge for environmental and health risks

Bulk Powder

Paper

Nanomaterial Challenges

Lithium Ion Challenges

• August 2006, Sony recalled all battery packs sold to Dell over a multi-year period

• March 2008, LG Chemical experienced a factory fire

• Concern for battery safety (e.g. electrolyte flammability)

• Environmental effects of constituent materials



Dr. Ryne P. Raffaelle

Dr. Cory D. Cress

Matt Ganter

Roberta DiLeo

Chris Schauerman

Jack Alvarenga

U.S. Government

Acknowledgements


brian j. landi - oecd

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