presented by

Michael M. Thackeray

Almaden Institute 2009Scalable Energy Storage: Beyond Lithium Ion

San Jose, CaliforniaAugust 26 - 27, 2009

Lithium-Ion Batteries:Challenges and Opportunities in an

Evolving Lithium Economy

2

Acknowledgments

Chris Johnson (ANL), Sun-Ho Kang (ANL), Vilas Pol (ANL),Lynn Trahey (ANL/NU), Jack Vaughey (ANL), Khalil Amine (ANL),Mali Balasubramanian (APS-ANL), Swati Pol (APS-ANL),Harold Kung (NU), Dongwon Shin (NU), Chris Wolverton (NU)

Department of Energy

• Vehicle Technologies ProgramOffice of Energy Efficiency and Renewable Energy

• Energy Frontier Research CenterCenter for Electrical Energy Storage: Tailored InterfacesOffice of Basic Energy Sciences

This presentation has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

3

The First Oil Crisis (mid 1970’s)

Non aqueous batteries - sodium or lithium?

High temperature systems (300-450C) already established

Na / -Al2O3 / S Chloride Silent Power, British Rail (UK)Brown Boveri (Germany)

LiAl / LiCl, KCl / FeSx Argonne National Laboratory (USA)

Oil crisis sparked the development of the sodium-metal chloride ‘Zebra’ battery (1978)

Na / -Al2O3 , NaAlCl4/ MCl2 (M=Ni, Fe) CSIR(South Africa)

Courtesy of www.copyright-free-pictures.org.uk

4

~884

380

787

754

~240

219

171

Th En.(Wh/kg)

~150~3403.3-2.0 (2.6)VOxLiLi-polymer

150-20095(for x=0.6)

4.2-3.0 (4.0)Li1-xMO2(M=Co, Ni, Mn)

LixC6Li-Ion

80-1003052.58 NiCl2NaNa-MCl2(300C)

120-1503772.1-1.78 (2.0)SNaNa-S (350C)

60-80~1781.35NiOOHMH alloyNi-MH

40-601621.35NiOOHCdNi-Cd

20-40832.1PbO2PbLead – acid

Pr. En.(Wh/kg)

Th. Cap(Ah/kg)

OCV(V)

Positiveelectrode

NegativeelectrodeSystem

Theoretical and Practical Properties of Batteries(theoretical values based on the masses of active electrode and electrolyte components)

Lithium-ion systems offer the best near-term opportunities What lies ‘beyond lithium-ion’?

5

Ragone Plot of Various Electrochemical Energy-Storage Devices

Source: Amended from Product data sheets

12

46

102

46

1002

46

1000S

peci

fic E

nerg

y (W

h/kg

)

100 101 102 103 104

Specific Power (W/kg)

Lead-Acid

Capacitors

IC Engine

36 s0.1 h1 h

10 h

Ni-MH

Li-ion

Lead-Acid

Capacitors

Li-Air?Fuel Cells

IC Engine

36 s0.1 h1 h

10 h

Ni-MH

Li-ion

Acceleration

Lead-Acid

Capacitors

IC Engine

HEV goal

3.6 s36 s0.1 h1 h

10 h

100 h

Ni-MH

Li-Ion

Ran

ge

EV goal (EoL)

PHEV-10 (EoL)PHEV-40 (EoL)

Na/NiCl2

6

Cells are assembled in the discharged state The close-packed Cl- lattice provides a stable framework for Na+ and M2+ ions The ‘insertion – displacement’ reaction is 100% efficient The volume expansion of the Cl- array during discharge = 45.6% Cells fail in short circuit mode – excellent for enhancing safety Excellent reversibility achieved through an electronically conducting

M matrix, and through control of M grain growth at 300 C Implications for room temperature reactions? Intermetallic compounds?

The Sodium-Nickel Chloride Battery

Cell Configuration: Na / -Al2O3, NaAlCl4 / NiCl2Operating Temperature: 300 CCell Reaction: 2 Na + NiCl2 Ni + 2 NaCl2.58 V

Photos: Courtesy of J. Coetzer and J. Sudworth, ‘Out of Africa’

7

The Advent of Li-Ion Batteries(Sony Corporation - 1991)

Lithium insertion/extraction reactions Highly energetic (4 V) systems Inherently unsafe; individual cells are protected from overcharge by

costly electronic circuitry Flammable electrolytes

scientific and technological motivation to discover and studyalternative electrodes and electrolytes

Cell voltage can be tailored by selection of anode and cathode materials

LixC6(Anode)

LiCoO2(Cathode)Li+

e-

8

Impact of Li-Ion Batteries

~$8-10 billion market created over the past 18 years

Applications: Consumer electronics and communications

Transportation (‘Li economy’ driver)Hybrid-electric vehicles ‘and plug-in’ HEVsPure electric vehicles – longer term viability

Implantable medical devicesNeuro-stimulators, pacemakers, defibrillators

Aerospace, defense, power tools, toys

Lithium batteries have become a strategic commodityin U.S. energy security

9

• Capacity limited to ~ 0.5 Li per M atom(i.e., ~140 mAh/g)

• Co4+ and Ni4+ unstable/highly oxidizing• Structure destabilized at low Li content• Layered LiMnO2 transforms to spinel

• Capacity limited to <0.5 Li/Mn at 4 V• Robust M2O4 spinel framework; 3-D channels• High rate capability• Jahn-Teller (Mn3+) distortion at 3 V• Solubility problems at high potentials

• Capacity limited to 1 Li/Fe; P inactive• Excellent structural and thermal stability• 1-D channels • Poor electronic and Li-ion conductivity• Poor packing density

Li-Ion Batteries: 3.5 – 4 V Cathode MaterialsOrderedRocksaltLayeredLiMO2(M=Co, Ni, Mn)

SpinelLiM2O4(M=Mn)

OlivineLiMPO4(M=Fe, Mn)

10

Li-Ion Batteries: Anode Materials Carbon

Graphite: <100 mV vs. Li0 Moderate capacity (372 mAh/g) Highly reactive, unsafe, SEI necessary

Metal Oxides Li4Ti5O12 (Li[Li1/3Ti5/3]O4) Spinel: 1.5 V vs. Li0 Low capacity (175 mAh/g) Very high rate capability Stable in nanoparticulate form

Metals, Semi-metals and intermetallic compounds Al, Si, CoSn, Cu6Sn5: <0.5 V vs. Li0 High gravimetric/volumetric capacities Large volume expansion on reaction with lithium Reactive, SEI necessary Greatest opportunity and challenge

LiC6

LiAl

Li7Ti5O12

11

Despite the good statistical safety record of batteries in consumerelectronics products, the occasional serious mishap does occur.

A significant number of recalls of lithium ion batteries Millions of passengers fly every month Millions of batteries fly every day In air travel, it only takes one So far, we’ve been lucky

Dan HalbersteinLithium Battery Public Awareness InitiativeU.S. Department of Transportation,25th Annual Battery Seminar, Fort Lauderdale, March 17-19, 2008

Hazards of Highly Energetic Batteries

During boarding, a laptop started burning in an overhead bin. The fire was extinguished on ramp.

2006 PhiladelphiaUPS flight– lithium batteries

to blame?

12

USABC HEV Battery Goals

0.50.3Available Energy, kWh35 (10s)20 (10s)Regen Power, kW40 (10s)25 (10s)Discharge Power, kW

12.57.5Available Energy, Wh/kg

75Cold Cranking Power*, kW-30 to 52Operating Temperature, oC

60Battery Mass, kg

800500Selling Price**, $

5Calendar Life, years

Max.Min.Power Assist HEV

Bar

riers

*Three 2s pulses at -30oC with 10s rest between pulses

**Price based on 100,000 batteries/year production level

13

7Cold Cranking Power*, kW-30 to 52Operating Temperature, oC

0.30.5Available Energy, kWh (Charge-Sustaining)4010Range, miles

3,4001,700Selling Price**, $

1515Calendar Life, years12060Battery Mass, kg

11.6~140

3.4~80

Available Energy, kWh (Charge-Depleting)Available Energy, Wh/kg

2530Regen Power, kW3845Discharge Power, kWCarSUV

Long-TermShort-Term

* Three 2s pulses at -30oC with 10s rest between pulses **Price based on 100,000 batteries/year production level

PHEV Battery GoalsB

arrie

rsB

arrie

rs

14

USABC EV Battery Goals

2:12:1Specific Power:Energy Ratio

-40 to +85-40 to +50Operating Temperature, oC3-66Normal Recharge Time, hr200267Battery Mass, kg

10001000Cycle Life – 80% DOD (Cycles)

100<4000

<150<6000

Selling Price – 25000 units, $/kWh@ 40 kWh, $

1010Life, years

200150Specific Energy, (C/3) Wh/kg300230Energy Density, (C/3) Wh/L400300Specific Power (80% DOD), W/kg600460Power Density, W/L

Long-Term GoalsMinimum Goals for Long Term

Commercialization

Parameter of Fully Burdened System

Bar

riers

Bar

r.

15

Major Challenges

Improve the energy and safety of Li-ion cells,without compromising power suppress oxygen release from high capacity metal oxide cathodes

on charge at high potentials find alternative anodes to graphite that provide a

high electrochemical capacity at 0.5 – 1.0 V vs. Li lithium alloys/intermetallic compounds, metal oxides?

Exploit nano-particulate electrodes access intrinsic capacity (energy) of electrodes at high rates LiFePO4, Li4Ti5O12; high potential metal oxides?

stabilize electrode surfaces (ANL-NU-UIUC EFRC)

find alternative electrolytes and additives

find effective redox shuttles to prevent overcharge

16

Use two-component ‘composite’ structures in which an electrochemically inactive Li2MnO3 component stabilizes anelectrochemically active layered or spinel component

layered-layered systems: xLi2MnO3(1-x)LiMO2

layered-spinel systems: xLi2MnO3(1-x)LiM2O4

M = Mn, Ni, Co

focus on manganese-rich systems (cost advantage)

Designing High Capacity and Safe Electrode Structures for High Voltage Lithium-Ion Cells

Argonne’s Approach:

17

Li2MnO3 (Li2OMnO2) is electrochemically inactive with respect tolithium insertion/extraction, whereas LiMO2 is active

Strategy: Embed inactive Li2MnO3 component within layeredLiMO2 structure to stabilize the electrode and to reduce the oxygenactivity at the surface of charged (delithiated) electrode particles

Structural Compatibility of Li2MnO3 and Layered LiMO2 Compounds

(M4+) (M3+ or M4+/M2+)Li2MnO3 LiMO2 (M = Mn, Ni, Co)

MO6octahedra

= Li = Li

18

Electrodes Solid Electrolytes

Use Structural Units (instead of ion dopants) to Stabilize Electrochemically–Active Materials

-MnO2 r-MnO2-MnO2 r-MnO2

Na+ conduction plane

Na+ conduction plane

Na+ conduction plane

inactive

spinelblock

inactive

spinelblock

AlNaO

Na+ conduction plane

Na+ conduction plane

Na+ conduction plane

inactive

spinelblock

inactive

spinelblock

AlNaO

AlNaO

-Al2O3

-Al2O3

Na+ conduction plane

Na+ conduction plane

Na+ conduction plane

inactive

spinelblock

inactive

spinelblock

AlNaO

AlNaO

Na+ conduction plane

Na+ conduction plane

Na+ conduction plane

inactive

spinelblock

inactive

spinelblock

AlNaO

AlNaO

-Al2O3

-Al2O3

INAg

-MnO2: Intergrowth of -MnO2 and ramsdellite-MnO2

Li2O-stabilized -MnO2:0.15Li2OMnO2

-alumina, Na2O11Al2O3 44AgI3(C11H22N3)I3

Li2OLi2O

19

Compositional Phase Diagram:xLi2MnO3(1-x)LiMn0.5Ni0.5O2 Electrodes

Li2Mn0.5Ni0.5O2 (Mn2+; Ni2+)

xLi2MnO3(1-x)LiMn0.5Ni0.5O2 tie-line

Li2MnO3 (Mn4+) LiMn0.5Ni0.5O2 (Mn4+; Ni2+)

Mn0.5Ni0.5O2 (Mn4+; Ni4+)

X=0.33X=0.50

X=0.67

(0.33Li2MnO30.67Mn0.5Ni0.5O2)

(Mn0.67Ni0.33O2; Mn4+; Ni4+)

(LiMn0.67Ni0.33O2; Mn3.5+; Ni2+)

(Li2Mn0.67Ni0.33O2; Mn2+; Ni2+)

-0.33Li2O

LixMn1-yNiyO2 tie-line(0x2)

Mn3+ concentration at the end of discharge is tailored by the Li2MnO3content in the parent electrode (x) to suppress the Jahn-Teller distortion

Li2O is removed from the Li2MnO3 component at high potentials (>4.5 V)

close-packedplanes

U.S. Pat. 6,677,082 (2004); U.S. Pat. 6,680,143 (2004)Johnson et al., Electrochem. Comm. (2004)

20

Electrochemistry of a Li/0.3Li2MnO30.7LiMn0.5Ni0.5O2 Cell (C/3)

Cycle Number

236

0

50

100

150

200

250

300

350

0 5 10 15 20 25 30 35 40 45

Spec

ific

Cap

acity

(mAh

g)

ChargeDischarge

01

23456

0 25 50 75 100125150175200225250Specific Capacity (mAh/g)

Cel

l Vol

tage

V v

s. L

i

Cycle 40

Li/0.3Li2MnO3●0.7LiMn0.5Ni0.5O2

4.8-2.75 V0.25 mA/cm2

50 °C

Irreversible capacity can be usedto offset SEI formation at anode

Average Mn valence in discharged state = 3.54

262mAh/g

90% oftheoreticalvalue

Cycle Number

236

0

50

100

150

200

250

300

350

0 5 10 15 20 25 30 35 40 45

Spec

ific

Cap

acity

(mAh

g)

ChargeDischarge

01

23456

0 25 50 75 100125150175200225250Specific Capacity (mAh/g)

Cel

l Vol

tage

V v

s. L

i

Cycle 40

Li/0.3Li2MnO3●0.7LiMn0.5Ni0.5O2

4.8-2.75 V0.25 mA/cm2

50 °C

Irreversible capacity can be usedto offset SEI formation at anode

Average Mn valence in discharged state = 3.54

262mAh/g

90% oftheoreticalvalue

Johnson et al., Electrochem. Comm. (2004)

21

Safety CharacteristicsxLi2MnO3(1-x)LiMO2 Cathode (M=Mn, Ni, Co)

150 200 250 300

0

10

20

30

40

Argonne cathodecharged to 4.6 VH=650j/g

Hea

t flo

w, W

/g

Temperature (C)

Thermal Stability (DSC)

Li[Ni0.8Co0.15Al0.05]O2charged to 4.2 VH=1550j/g

150 200 250 300

0

10

20

30

40

150 200 250 300

0

10

20

30

40

Argonne cathodecharged to 4.6 VH=650j/g

Hea

t flo

w, W

/g

Temperature (C)

Thermal Stability (DSC)

Li[Ni0.8Co0.15Al0.05]O2charged to 4.2 VH=1550j/g

Courtesy of K. Amine, Argonne National Laboratory

22

The Challenge of Surface Stabilization

Charging high-capacity xLi2MnO3(1-x)LiMO2 electrodes to a highpotential (>4.4 V) damages the electrode surface and reduces the ratecapability of the electrode:

(1) LiMO2 MO2- + Li+ + /2 O2 + (1+2)e

(2) Li2MnO3 MnO2 + 2 Li+ + O2 + 2e

Oxygen loss, particularly through process (1), increases M cationconcentration at the electrode surface that restricts Li diffusionand rate capability? LixNi1-xO rock salt structure at surface of Li1-xNi0.80Co0.15Al0.05O2

How does one prevent corrosion and cation disorder at the surfaceto allow high rate discharge and charge? (Thrust of EFRC)

23

Fluorination

Fluorination of layered xLi2MnO3(1-x)LiMO2 electrodes (e.g., LiF, AlF3 -Sun et al., Amine et al.) is known to improve capacity and cycling stability.

F- ions within the bulk or at the surface? – gradient?

Alternative Approach

Use mildly acidic solutions containing fluorine to form robust oxy-fluoride (partially reduced) surface on electrode particles lowering oxygen activity.

Use soluble salts with stabilizing cations and anions, e.g., (NH4)3AlF6;NH4PF6; NH4BF4 in water, methanol, etc

Molarity of solutions ~2.5 x 10-3 M; pH 6.0 - 6.5

pH can be varied to tailor stability and first-cycle irreversibility loss

24

Relative Rate Capability: Li-ion cellsC6/0.1Li2MnO30.9LiMn0.256Ni0.372Co0.372O2

Fluorinated electrodes provide higher capacity, lower impedance and improved rate: ~175 mAh/g at C/1 rate Insufficient energy/power for 40-mile PHEVs. Yardstick for PHEV: 200 mAh/g at a C/1 rate, average 3.5 V (or higher)

0.1mA/cm2

0.2mA/cm2

0.5mA/cm2 1

mA/cm2

0.1mA/cm2

1mA/cm2

2mA/cm2

5mA/cm2

0 5 10 15 20 25100

150

200

Cap

acity

/ m

Ah

g-1

Cycle Number

Sample A Sample B Sample C Sample D

Sample Auntreated sample

4.5-3.0 V

~C/1 rate

0.1mA/cm2

0.2mA/cm2

0.5mA/cm2 1

mA/cm2

0.1mA/cm2

1mA/cm2

2mA/cm2

5mA/cm2

0 5 10 15 20 25100

150

200

Cap

acity

/ m

Ah

g-1

Cycle Number

Sample A Sample B Sample C Sample D

Sample Auntreated sample

4.5-3.0 V

0.1mA/cm2

0.2mA/cm2

0.5mA/cm2 1

mA/cm2

0.1mA/cm2

1mA/cm2

2mA/cm2

5mA/cm2

0 5 10 15 20 25100

150

200

Cap

acity

/ m

Ah

g-1

Cycle Number

Sample A Sample B Sample C Sample D

Sample Auntreated sample

0.1mA/cm2

0.2mA/cm2

0.5mA/cm2 1

mA/cm2

0.1mA/cm2

1mA/cm2

2mA/cm2

5mA/cm2

0 5 10 15 20 25100

150

200

Cap

acity

/ m

Ah

g-1

Cycle Number

Sample A Sample B Sample C Sample D

Sample Auntreated sample

4.5-3.0 V

~C/1 rate

Kang et al., J. Electrochem. Soc. (2008)

25

Integrated Olivine-Metal Oxide Structures/Surfaces?

Olivine (LiFePO4) and Spinel (LiMn2O4) both have AB2O4formulae with the A cations in tetrahedral sites and the B cationsin octahedral sites

In LiFePO4, the P cations are in tetrahedral sites In LiMn2O4, the Li cations are in tetrahedral sites Olivine has a hexagonally close packed structure Spinel has a cubic close packed structure Relatively small difference in the d-spacings of the close-packed

layers in LiFePO4 and LiMn2O4

Can we synthesize ‘olivine-spinel’ composite structures, ‘olivine-layered’ structures or other close-packed phosphate structures to stabilize ccp spinel and layered metal oxide bulk structures and/or surfaces?

26

Hypothetical LiNiVO4 Spinel – LiNiPO4 Olivine Intergrowth

Spinel LiNiVO4

tetrahedral V5+

octahedral Li+, Ni2+

Olivine LiNiPO4

tetrahedral P5+

octahedral Li+, Ni2+

ccp O layers

hcp O layers

In principle, a spinel-olivine intergrowth structure seems possible Experiment shows otherwise: CBED patterns and EDS signals

(Ni/V or Ni/P) suggest that discrete olivine and spinel phases exist Can Li-M-PO4 films provide effective surface protection on metal oxides?

Vaughey et al., Argonne National Laboratory

27Figure 3

2.0

3.0

4.0

2.0

3.0

4.0

Cel

l vol

tage

(V)

0 50 100 150 200 250 300Capacity (mAh/g)

untreated

treated

C/1(1.0)

C/3(0.5)

C/8(0.2)

C/16(0.1)C/1

(1.0)

C/2(0.5)

C/5(0.2)

C/11(0.1)

Treated electrodes meet the 200 mAh/g, C/1 rate, 3.5 V average, capacity/power yardstick for a 40-mile range PHEV at room temperature

Li-M-PO4 surface treatment (e.g., M=Ni)(0.5Li2MnO30.5LiNi0.44Co0.25Mn0.31O2 electrodes in Li half cells)

Concept: Use Li-Ni-PO4 as a solidelectrolyte below 5.0 V to protectsurface of xLi2MnO3(1-x)LiMO2electrode at high potentials

Sol-gel treatment technique used Olivine LiNiPO4, Li3PO4 or defect

Li3PO4, e.g., Li3-2xNixPO4? First-principles calculations indicate

a small solid solution range inLi3-2xMxPO4 materials (Shin, Wolverton(NU – EFRC))

Kang et al., Electrochem. Comm. (2009)

28

Relatively low energy cells (2.5 V) Outstanding power and cycling stability Safety is achieved by operating well above the potential of metallic lithium Being developed for HEV applications

Before ARC test After ARC test

Playing it SafeLi4Ti5O12 (Spinel) / Li1+xMn2-xO4 (Spinel) Cells

Courtesy of K. Amine and Enerdel

LiMn2O4 vs. GraphiteLiMn2O4 vs. Li4Ti5O12

0 100 200 300 400 5000123456789

1011121314

Cap

acity

, mA

h

Cycle number

6C

6C

55 C LiMn2O4 vs. GraphiteLiMn2O4 vs. Li4Ti5O12

0 100 200 300 400 5000123456789

1011121314

0 100 200 300 400 5000123456789

1011121314

Cap

acity

, mA

h

Cycle number

6C

6C

55 C

55 C

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

0 10 20 30 40 50 60 70 80 90 100 110

% of 1C Capacity

Volta

ge(V

)

2C5C10C20C30C40C50C

2C - 50C rates

29

TiO2 Anodes?

Li4Ti5O12 (2Li2O5TiO2) spinel accommodates 3 Li+ ions per formula unit during its transformation to rock-salt Li7Ti5O12(Ti4+ to Ti3.4+): relatively low capacity – 175 mAh/g

TiO2 structures, e.g., anatase, rutile, hollandite and TiO2-Bwould be more attractive anodes if, in nanoparticulate form, they could accommodate lithium reversibly and rapidly to the rock-salt stoichiometry LiTiO2 (Ti3+), for which the theoretical capacity is 335 mAh/g.

30

A single-step, autogenic (solvent-less), and scalableprocess has been used to prepare single-phase TiO2(anatase) nanoparticles encapsulated by an interconnected,electronically-conducting network of carbon nanoparticlesthat also protect the surface.

EDS

XRD

Carbon-Encapsulated TiO2-C Anodes

V. Pol et al., Argonne National Laboratory

31

FESEM and HRTEM images of C-coated TiO2

The images demonstrate the likelihood that every TiO2 nanoparticle is completely encapsulated by a 2-4 nm layer of x-ray amorphous carbon, the thickness of which can be tailored by the temperature and length of the carbon combustion process.

V. Pol, Thackeray et al., Argonne National Laboratory (EFRC)

32

200 mAh/g is delivered by both the TiO2 anode and metal oxide cathode Cells provide higher energy than Li-ion cells with Li4Ti5O12 anodes The autogenic process can be used to prepare a wide variety of

C-protected nanoparticulate materials; the approach has implicationsfor advancing the electrochemical properties of both anode and cathodenano-materials.

TiO2-C/0.5Li2MnO30.5LiNi0.44Co0.25Mn0.31O2 Cells

V. Pol, Thackeray et al., Argonne National Laboratory (EFRC)

33

Alternative Anodes for Li CellsLithium Alloys and Intermetallic Compounds

Metals have dense structures and therefore expandsignificantly on reaction with Li, e.g. Al, Si, Sn, Sb

Fm-3mFd-3m, 50% Al in interstitial sites

95% Volume Expansion

(per Al atom)

+ Li

300 mV

LiAl

Major structural rearrangement on lithium insertion Lithium alloys offer significantly higher gravimetric and

volumetric capacities than graphite (372 mAh/g; 820 mAh/ml)

Al

34

Cu6Sn5 Anodes

21.25 Li + Cu6Sn5 5 Li2+xCu1-xSn + (1+5x) Cu 6 Cu + 5 Li4.25Sn

Strong structural relationship between Cu6Sn5, Li2CuSn and “Li3Sn” (x=1) exists.

Li insertion/Cu displacement reaction: Max capacity 600 mAh/g.

Mimics Na/NiCl2 reaction (100% efficient): 2 Na + NiCl2 2 NaCl + Ni.

Cells assembled in discharged state; NaCl powder in porous Ni substrate.

Volume expansion 50-60%.

Li

400-200 mV

CuSnLi

CuSnLi

Li

400-200 mV

CuSnLi

CuSnLi

Cu6Sn5 to Li2CuSn transition Electrochemistry: Cu6Sn5 vs. Sn

0

50

100

150

200

250

300

350

400

0 5 10 15 20 25Cycle Number

Cel

l Cap

acity

(mAh

/g) Sn (1.2 V - 0.0 V)

Sn (1.2 V - 0.2 V)Cu6Sn5 (1.2 V - 0.0 V)

Cu6Sn5 (1.2 V - 0.2 V)

Cu6Sn5

Sn

0

50

100

150

200

250

300

350

400

0 5 10 15 20 25Cycle Number

Cel

l Cap

acity

(mAh

/g) Sn (1.2 V - 0.0 V)

Sn (1.2 V - 0.2 V)Cu6Sn5 (1.2 V - 0.0 V)

Cu6Sn5 (1.2 V - 0.2 V)

0

50

100

150

200

250

300

350

400

0 5 10 15 20 25Cycle Number

Cel

l Cap

acity

(mAh

/g) Sn (1.2 V - 0.0 V)

Sn (1.2 V - 0.2 V)Cu6Sn5 (1.2 V - 0.0 V)

Cu6Sn5 (1.2 V - 0.2 V)

Cu6Sn5

Sn

New approach to electrode design and current collection is requiredKepler et al., Electrochem. and Solid-State Lett. (1999)

35

Electrodeposited Cu6Sn5/Sn on Cu Foam Electrodes

1. As-deposited Cu foam 2. Annealed Cu foam (500 C) 3. Cu6Sn5/Sn on Cu foam

1. As-deposited Cu-foam is brittle and powdery.

2. Annealing at 500 C strengthens Cu-foam to Cu foil contact, providing asufficiently robust substrate for electrodeposition of Cu and Sn. Overallporosity maintained.

3. Morphology maintained after Cu6Sn5/Sn pulsed electrodeposition at -600mVvs. SCE. Sn concentration varies from ~20% within the porous electrode to ~90% at outermost surfaces.

Trahey et al., J. Electrochem. Soc. (2009)

36

Electrochemistry: Cu6Sn5/Sn on Cu Foam Electrodes

Significant improvement in reversible capacity achieved (650 mAh/g vs. 200 mAh/gfor ball-milled Cu6Sn5 samples).

Results suggest excellent cycling of Sn within a copper-tin matrix electrode.

Large irreversible capacity drop during early cycles attributed to electrolytereactions with high surface area electrode to form passivation layer.

Abrupt onset of capacity fade after 30 cycles - Li electrode or mechanical failureof Cu6Sn5/Sn electrode?

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Trahey et al., J. Electrochem. Soc. (2009)

37

~13,000 (ex. O)-C8H18 + 12.5O2 8CO2 + H2OOctane

~9003.6LixC6 + Li1-xMO2 C6 + LiMO2Lithium-ion(M=Mn, Ni, Co)

3623 (incl. O)5204 (incl. O)

11,202 (excl. O)

3.12.92.9

2 Li + O2 2 Li2O24 Li + O2 2 Li2O4 Li + O2 2 Li2O

Li/O2

Th. Spec. Energy(Wh/kg)

OCV(V)

ReactionSystem

Beyond Lithium-Ion: Li-Air – The Holy Grail?

Li-containinganode

Porous C cathodewith catalyste.g., MnO2

Li-ion conductingelectrolyte

O2

O2

O2

O2

O2

O2

O2

Li-containinganode

Porous C cathodewith catalyste.g., MnO2

Li-ion conductingelectrolyte

O2

O2

O2

O2

O2

O2

O2

38

Li2MnO3 (Li2OMnO2) MnO2 + 2 Li + ½ O2 (459 mAh/g)

Net loss is Li2O at 4.5 to 4.8 V – irreversible reaction

Two Li+ ions removed during electrochemical activation (charge)

One Li+ ion reinserted into residual MnO2 component:

Li + MnO2 LiMnO2 (229 mAh/g, mass of parent electrode) Use surplus Li to load anode: C6, metals or even bare substrate (Li metal)

Use Li2MnO3 (or xLi2MnO3(1-x)LiMO2, M=Mn, Ni, Co) precursor incombination with high capacity charged cathodes, particularly where twoelectron transfer reactions are possible, e.g., Li1.2V3O8 (372 mAh/g)

Exploitation of Li2O-Containing Electrodes: Electrochemical Activation of Li2MnO3

4.5-4.8 V

39

Li-O bonds in Li2MnO3 cathode precursor are broken at ~4.5 V vs. Li0

Li is inserted into C6 anode during charge During discharge, Li is inserted charged Li1.2V3O8

and residual MnO2 cathode components Implications for Li - O2 cells using MnO2 component as catalyst?

C6/Li2MnO3Li1.2V3O8 Cells

Kang et al., Argonne National Laboratory

40

Li2O: Li - tetrahedral sitesO - face-centered-cubic sites

Defect structures Li5FeO4: 5Li2OFe2O3 or Li1.25Fe0.25□0.5O

5 Li per Fe atom

Li6MO4 (M=Mn, Co, Ni):3Li2OMO or Li1.5M0.25□0.25O6 Li per M atom

cf: Layered Li2MnO3 (Li2O:MnO2)2 Li per Mn atom

Alternative High-Li2O Content PrecursorsAntifluorite structures

Li2O (Fm-3m)(a=4.614 Å)

Li5FeO4 (Pbca)(a=9.218 Å; b=9.213 Å; a=9.159 Å )

Abundant Li in defect structure provides good Li+ mobility

LiO

LiFeO

41

Electrochemical Extraction of Li from Li5FeO4

4 Li removed from Li5FeO4 (5Li2OFe2O3) in 2 steps at ~3.5 and ~4.0 V Slight evidence from XANES data of some Fe3+ Fe4+ oxidation

predominantly Li2O extraction? Composition of delithiated product = “LiFeO2” (Li2OFe2O3) Exploit reversibility of the reaction when discharged against O2 electrode

(Li2O content increases in the residual Fe2O3 electrode matrix) Johnson et al., Argonne National Laboratory

42

Li5FeO4 samples chemically delithiated with NO2BF4/acetonitrile solution No apparent change in Fe3+ oxidation state Li2O extraction EXAFS shows evidence of formation of edge-shared Fe-octahedra as x. Gradual reduction in pre-edge peak height is consistent with conversion from

tetrahedral Fe to octahedral coordination and ultimate ‘LiFeO2’ stoichiometryS. Pol, M. Balasubramanian et al., APS - Argonne National Laboratory

XANES Data: Chemical Delithiation of Li5FeO4

decreasingpre-edge features

no change in edge position(iron oxidation state)

decreasingpre-edge features

no change in edge position(iron oxidation state)

43

Summary Remarks Lithium-ion technology stands to broaden its impact on battery markets. Extremely versatile, strategic technology - battery chemistry can be

tailored to suit needs. State-of-the-art lithium-ion batteries still compromised by safety, energy,

power, life, operating temperature and cost constraints New, structurally-stable materials required:

Exploitation of high potential metal oxide electrodes (>4.2 V) to increase energy and power

Composite cathode structures with high-capacity (layered) /high-power (spinel) components?

Nano-particulate metal, semi-metal or intermetallic anodes to replace graphite - increase both specific- and volumetric capacity?

Electrode surface protection – use of additives Non-flammable electrolytes

Li-air: the ultimate scientific and engineering challenge?