Overview on current status of lithium-Ion batteries

Second International Renewable Energy Storage Conference

19.-21. November 2007 Bonn/Germany

Andreas Jossen, Margret Wohlfahrt-Mehrens

Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW)Helmholtzstrasse 8, 89081 Ulm, Germany

Contact: andreas.jossen@zsw-bw.de

- 2 -

Overview

• Why is Lithium an interesting material for batteries?

• Principle of Li-Ion batteries

• Possible Material combinations

• Today’s driving forces for Li-Battery development

• State of the art technologies

• Chances and risks of using large lithium batteries for stationary applications

• R&D required

• Lifetime, costs and economical aspects

- 3 -

Why Lithium?

-4 -3 -2 -1 0 1 2 3 4

Ag

Cu

Pb

Ni

Cd

Fe

Zn

Mn

Al

Na

Li

Potential vs hydrogen in V

Lithium is the material with the most negative voltage high cell voltage

0 2 4 6 8 10 12

Pb

Ag

Cu

Ni

Cd

Fe

Zn

Al

Mg

Na

Li

Density in kg/l

Lithium is the metal with the lowestdensity. high specific Energy

- 4 -

Why Lithium?

Lithium is able to form a protection layer that allows the transport of Li-Ions

Layer does not block current flow

Layer protects electrode good lifetime is possible

Li-M

etal

Li-Ion

Protection Layer protects Lithium for further dissolution(Solid electrolyte interface / SEI)

Ele

ctro

lyte

Lithium can be used for Batteries with

high cell voltage and high specific energy

- 5 -

Possible Lithium Systems

*E. J. Cairns, in “Lithium Battery Technology”, ed. by H. V. Venkatasetty, John Wiley & Sons (1984) 179

Li-Ionen

- 6 -

Types of Lithium Batteries

Li-Batteries

Systems withmetallic Lithium:

Li-Metal

Systems withintercalated Lithium:

Lithium-Ion

Differentiation byanode material

Differentiationby electrolyte

Liquid electrolyte:

Li-Metal-liquid

Polymerelectrolyte:

Li-Metal-Polymer

Flüssiger electrolyte:

Li-Ion-liquid

Polymerelectrolyte:

Li-Ion-Polymer

Button cellsonly

France: BolloréCells available for cellphones, laptops, PDA, first larger cells

Preferred systems

- 7 -

The Lithium-Ion SystemPOSITIVE

LiMO2

NEGATIVECarbonOrganic

electrolyte

Metal Ion (Co, Ni, Mn)

Oxygen

Separator

e-discharge charge

Li+

Li+

Li+ Li+

Passivating layer

Li+, LiC6

Cell reactions: Discharged ChargedPositive: LiCoO2 ↔ Li1-xCoO2 + x Li+ + x e-

Negative: x Li+ + C6 (graphite) + x e-↔ LixC6Total reaction: LiCoO2 + 0.6 C6 ↔ Li0.4CoO2 + 0.6 LiC6

No Li metal in the cell. The electrolyte does not participate in the cellreaction. It constitutes only a vehicle for Li-Ion transfer. No excess of electrolyte is therefore required.

- 8 -

Cell design of Li-Batteries

Source: LTC-GAIA

Thin electrodes are necessary!

- 9 -

Cylindrical cell

Cell design of Li-Batteries

Prismatic cells

Coffee bag cells

- 10 -

Cell design of Li-Batteries

Quelle: http://www.greencarcongress.com/ , 10. Nov 2005

Electro Energy Inc. received 1.5 Mio US $ for developing of a bipolar Li-Battery

- 11 -

Battery System for Plug-In Hybrid

Source: GAIA

Li-Ion Battery63 cells (LiFePO4)200V / 35Ah (7 kWh)

Battery-management withsingle cell voltagemonitoring and charge-equalizing is required.

- 12 -

High Energy Storage

0

100

200

300

400

500

0 50 100 150 200

specific energy in Wh/kg

ener

gy

den

sity

in W

h/l

Lead-acid

NiCd

NiMH

Li-Ionen

Redox-flow

DLC

- 13 -

Good Performance Achieved

90

91

92

93

94

95

96

97

98

99

100

0 2 4 6 8 10

Discharge time/ Charge time in h

Ene

rgy

Eff

icie

ncy

Li-Ion Cell: Saft MP176065 HDHigh Power TypeTemperature: 25°C

Lithium Batteries show anexcellent energy efficiency.

> 95% ( 2 h Rate)> 98% (10 h Rate)

0

20

40

60

80

100

120

0 500 1000 1500 2000 2500 3000 3500

Zyklenzahl

Kap

azit

ät in

% C

N

Cycle life test :DoD: 100%T: 25°CRate: 1/2 h

Lithium Batteries show along cycle life.

3000 cycles today

LiFePO4 System

- 14 -

Materials for Lithium-Ion-Batteries

Ele

ktro

lyte

4

3

0

1

2

5

4

3

0

1

2

5

LiMn2O4

LiCoO2

LiNiO2

LiFePO4

Li4Ti5O12

LiSiGraphit

Kohleamorph

Li-Metall

Sp

ann

un

g g

ege

n L

i-M

eta

ll /

V

MnO2

LixV3O8

4-V Systeme

3-V Systeme

Positive

Negative

•PTMA

4

3

0

1

2

5

4

3

0

1

2

5

LiMn2O4

LiCoO2

LiNiO2

LiFePO4

Li4Ti5O12

LiSiGraphit

Kohleamorph

Li-Metall

Sp

ann

un

g g

ege

n L

i-M

eta

ll /

V

MnO2

LixV3O8

4-V Systeme

3-V Systeme

Positive

Negative

4

3

0

1

2

5

4

3

0

1

2

5

LiMn2O4

LiCoO2

LiNiO2

LiFePO4

Li4Ti5O12

LiSiGraphit

Kohleamorph

Li-Metall

Sp

ann

un

g g

ege

n L

i-M

eta

ll /

V

MnO2

LixV3O8

4-V Systeme

3-V Systeme

Positive

Negative

•PTMA

LiNiO2

Po

ten

tial

vs.

Li/L

i+ in

V

- 15 -

New Cathode Materials

3V

4V

5V

150 200 250 300

Li(Ni,Co)O2

LiFePO4

LiCoPO4

LiCo1/3Ni1/3Mn1/3O2

Li2MnO3/1-xMO2

LiNi1/2Mn1/2O2

MnO2 – V2O5

Doped MnO2

LiMnPO4

5V LiMn1.5(Co,Fe, Cr)0,5O4

LiMn2O4 LiCoO2

LiMn1.5Ni0.5O4

3V

4V

5V

150 200 250 300

Li(Ni,Co)O2

LiFePO4

LiCoPO4

LiCo1/3Ni1/3Mn1/3O2

Li2MnO3/1-xMO2

LiNi1/2Mn1/2O2

MnO2 – V2O5

Doped MnO2

LiMnPO4

5V LiMn1.5(Co,Fe, Cr)0,5O4

LiMn2O4 LiCoO2

LiMn1.5Ni0.5O4

Capacity [Ah/kg]

Po

ten

tial

vs.

Li/L

i+

Cathode is limitingLiCoO2 ~ 150 mAh/gGraphite ~ 320 mAh/g

Cathode with higher capacity safety and lower costs necessary

- 16 -

New Anode Materials

Capacity [Ah/kg]

• „zero-strain“• without side reaction• long lifetime• safe

• high capacity• high volume change• Nano-composite!!

Po

ten

tial

vs.

Li/L

i+

0,5 V

1,0 V

1,5 V

500 1000 1500 2000

Nano-OxideCo3O4

Hard carbon

Sn-alloys

Li2.6Co0.4N

Li4 Ti5O12

Si/C composites; Si alloys

Graphite0,5 V

1,0 V

1,5 V

500 1000 1500 2000

Nano-OxideCo3O4

Hard carbon

Sn-alloys

Li2.6Co0.4N

Li4 Ti5O12

Si/C composites; Si alloys

Graphite

nano TiO2

- 17 -

Today's Driving Forces in Li-Battery development

Mobile electronics (cellular phone, Laptop etc.) // < 100Whvery high specific energy, low cost, 2-3 years/200 cycles lifetime

Hybrid Electric Vehicle (HEV) // 1 kWhhigh specific power, low cost, safety,>12 years lifetime@ shallow cycling

Plug in Hybrid Electric Vehicle (PHEV) // 5-20 kWhmedium specific power, high specific energylow cost, safety,> 12 years lifetime@ deep cycling (4000 cycles)

- 18 -

Power and Energy of Li-Ion Batteriesfor different target applications

0

500

1000

1500

2000

2500

3000

3500

0 50 100 150 200 250

Spezifische Energie in Wh/kg

Sp

ezi

fisch

e L

eis

tun

g in

Wh

/kg

Li-Ion für HEV

Li-Ion für Geräte

Li-Ion für E-Fahrräder

Li-Ion für Powertools

NiMH

Li-Ion for HEV

Li-Ion for powertools

Li-Ion for e-bikes / EV

Li-Ion for mobile electr.

Specific energy in Wh/kg

Sp

ecif

ic p

ow

er in

W/k

g

- 19 -

Technology Trends for Mobile ElectronicsIncrease off Cell capacity- New anode materials

Si (Panasonic) based materials Sn (Sony) based materials

- New Cathode Material to achieve higher cell voltage/higher capacity

NCA (Panasonic, Sony)NMC (Sanyo)

Increase of battery safety- Development of heat resistance layer (HRL)

Ceramic coated anode or cathodeHeat resistance polymerCeramic coated Separator

Lifetime is no critical factorThe increase of cell capacity will reduce lifetime- 2 years calendar life- 200 cycles

Capacity

Vol

tage

vs.

Li/L

i+

Sn .Si

Graphite

LiCoO2

NMC

NCA

- 20 -

Additive for Shuttle-Process in Li-Ion Batteries as substitute for electronic charge equalization systems

+

- +

S S++e-S++e- S

- 21 -

Technology Trends for Hybrid Electric Vehicles

Increase in power- Increase of conductivity

Coating of Active material with carbon

- Increase of active areaSmaller particles and nano size particles

Increase in low temperature performance- New electrolytes- smaller particle size

Increase in battery safety- New cathode materials (LiFePO4) - New separator- Safer electrolyte

Increase in Lifetime- Stable cathode (LiFePO4)- Improved electrolyte- Optimized control strategy- Calendar life at high SOC maybe critical

CapacityV

olta

ge v

s. L

i/Li+

Sn .Si

Graphite

LiFePO4

LiCoO2 Lower voltage reduces electrolyte decomposition.

- 22 -

Li-Ion Batteries for Power Assist HEVStatus: Comparison with FreedomCar targets

Quelle: 2006 Annual progress report FreedomCar Group

- 23 -

Requirements for Stationary Li-Batteries

Increase of power low priority

Increase of low temperature performance low priority

Increase of battery safety important- New cathode materials (LiFePO4) - New separator- Safer electrolyte

Increase of Lifetime important- Increase in cycle life

Zero strain anode? Gives low cell voltage! - Increase in calendar life at high state of charge

Stable cathode (LiFePO4)Improved electrolyteOptimized control strategy

CapacityV

olta

ge v

s. L

i/Li+

Sn .Si

Graphite

LiFePO4

LiCoO2 Lower voltage reduces electrolyte decomposition.

Li4 Ti5O12Li4 Ti5O12

- 24 -

Long Life 2V Lithium Battery

Source: Tsutomu Ohzuku, IMLB 2006

2V2.5V

Long cycle life possible(10 000 cycles + ?)

Long calendar lifetimeat high state of charge(10 years + ?)

But- only 50% of energy- higher costs per Wh- more resources necessary- more cells necessary

- 25 -

Battery Safety

The safety of Li-batteries can becritical. Million of batteries were recalled in the last 2 years.

For large stationary systemssafety is more critical. Must be solved by- new cathode materials- new electrolytes- Battery / cell design

- 26 -

Thermal Stability of different Cathode Materials

150 200 250 300 350Temperatur /°C

-0.2

0

0.2

0.4

0.6

DSC /(mW/mg)

[

[

[

[4.1]

ExoLi0.2Ni0.8Co0.15Al0.05O2

Li0.5CoO2

Li0.15Mn2O4

“Li0.1FePO4” no exotherm

reaction in charged state

- 27 -

A lithium-economy has some limitations

Lithium Nickel Zinc

Source: Meridian International Research

battery technology

- 28 -

The trouble with Lithium

Source: Meridian International Research

If Li batteries will enter automotive an stationary applications in relevant Market share we have to work on:- Recycling of Li from used batteries- Activating of Li resources- Developing of Li batteries with high cell voltage- Looking for none Li battery technologies

Global Lithium Reserve Base

- 29 -

R&D in Li-Batteries

Source: Namura-Report 2006

- 30 -

R&D required for large stationary Li-Batteries

- Further improvement of intrinsic battery safety by use of new cathode materials and improved electrolytes and separators.

- Cost reduction, by new cathode materials, improved engineering and finally mass production.

- Development of Li-batteries that are optimized for stationary applications. Today most R&D is concentrated on mobile electronics and automotive applications.

- Development of new, long-life generation of lithium batteries (2V types are maybe an option).

- Control strategy for lithium ion batteries is totally different from that of other battery technologies.

- Battery state determination methods for LiPFO4 and other systems with flat discharge voltage curve.

- 31 -

Summery• Li-batteries show the highest specific energy (up to 200 Wh/kg) of available rechargeable battery systems.

• Today Li-batteries are market leader in portable power sources

• Li-batteries have a high technology potential for further improvement. Today >90% of battery R&D is done on Li-batteries.

• Upscaling of lithium batteries from 100 Wh storage to large stationarysystems requires further R&D with the targets:- lower costs- improved battery safety- longer lifetime

• New Li-battery technologies optimized for stationary applications will show excellent performance, but some technologies will have higherspecific costs.

• A “Lithium economy” is maybe limited by the available Li-resources.

• Lithium battery R&D in Europe low

• Worldwide no Li-battery R&D focus on stationary applications