SOLID ELECTROLYTE BATTERIES - Department of Energy · The University of Texas at Austin SOLID ELECTROLYTE BATTERIES John B. Goodenough and Yuhao Lu. Texas Materials Institute. The

The University of Texas at Austin

SOLID ELECTROLYTE BATTERIES

John B. Goodenough and Yuhao Lu

Texas Materials Institute


DOE Vehicle Technologies Annual Merit Review Meeting

May 9-13, 2011

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This presentation does not contain any proprietary or confidential information.

Project ID: ES060


Overview

• Project Start Date-Oct. 2009

• Project End Date- Sept. 2010

• Percent complete: 100% complete

• Lithium-ion solid electrolyte.

• Choice of redox couples.

• Flow-through- cathode cell design

• Funding received in FY09-FY10

– $315K

• Funding received in FY10-FY11

– $315K

Timeline

Budget

Barriers

• Karim Zaghib of Hydro Quebec

Partners

2


Milestones

Develop and test a suitable test cell. (Jan. 10) Completed

Optimize components of the cell. (Apr. 10) Completed

Develop a lithium/Fe(NO3)3 cell. (July. 10) Completed

Design of a new cell (Sept. 10) Completed

Test flow-through cell (Jan. 11) Completed

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Typical Lithium Ion Battery (LIB) Cell

Capacity limited by Li solid solution in cathode and loss in SEI layer

Voltage limited by Eg of carbonate electrolyte.

4

Anode(Reducing Agent)

Cathode(Oxidizing Agent)

Electrolyte

e-

Li+

e-

Li+

Li+

- +Separator

SEI layer


Why Oxides?

Holes form peroxide (O2)2- for x> 0.55 or H+ inserted from electrolyte.

At surface, 2(O2)2- =2O2-+O2↑

Note: Li1-x(Co0.15Ni0.85)O2 (0<x<0.8) at 3.8 V versus Li0.

Note: Introduction of Mn(IV) stabilizes top of O: 2p6 bands to above 4.7 V versus Li0.

5

LiCoO2

Co(II): t4e2

Co: 4s0

O: 2p6

E

N(E)

Co(III): t6e0

EFCCo(IV): t5e0

Co: 4s0

O: 2p6

E

N(E)

Co(III): t6e0

EFC (pinned)

4.0 eV

µLi

Li1-xCoO2 (0<x<0.55)


Carbonate Electrolyte

Li0 - e-=Li+; dentrites on recharge because of SEI layer.

LiC6 - e- = 6C + Li+; SEI layer prevents rapid charge, consumes Li from cathode.

Alloy anodes undergo displacement reactions, which give large volume change.

Can be buffered by C and have voltages allowing fast charge, but SEI layer if V<1 V.

Need µC matched to HOMO or, with Li+-permeable SEI layer, to decomposition voltage.6

Decomposition

0.2 eV 0.5 eV

HOMO

LUMO

µLi0

1.1

4.3

5.0

1.5 eV3.45 eV

µLiC6

4.0 eV4.75 eVµLFP

µAlloy

µLTO

µLNC

µLNM


Existing Insertion Compound Electrodes

Lithium metal has the highest specific energy of 3860 mAh/g. No cathode materials can match the capacity.

Can we use lithium anode and develop a cathode with a capacity to match?

7

HOMO

LUMO

Organic electrolyte


Existing Electrolytes

8

0

1

2

3

4

5

6

Li+ ion Conductivity (mS/cm)

Poten

tial (V

) vs.

Li+ /Li

720.02 1 40.18 0.810.03

Inor

gani

c So

lid

Org

anic

Liq

uid

Ioni

c Li

quid

Ioni

c Li

quid

+ P

olym

er +

O

rgan

ic L

iqui

d

Ioni

c Li

quid

+ P

olym

er

Poly

mer

Poly

mer

+ O

rgan

ic L

iqui

d

Ioni

c Li

quid

+ O

rgan

ic L

iqui

d

1) High Li+ ion conductivity

2) Wide electrochemical window

3) Retention of electrode/electrolyte interface

4) Chemical stability

5) Safety (nonflammable)

Li-ion Conductivity ( ×10-3 S/cm)


Li Batteries Using a Solid Electrolyte Separator

Concept

Present Practice (Visco, PolyPlus Battery Company)

Proposed Practice

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LiOrganic Liquid

Or nothingInorganic

Solid

Air or S8Aqueous (Fe3+/Fe2+) flow

through

Li1M LiPF6 in

EC/DECLi1.3Ti1.7Al0.3(PO4)3 Sea Water

Li3N

Li1M LiPF6 in

EC/DECLi7Zr2R3O12

Fe(CN)63-/Fe(CN)6

4- flow through

Li + Fe(CN)63-(aq) = Li+ + Fe(CN)6

4-(aq); E=3.40 V

Objectives:


Solid Electrolytes

• All Solid-State Cell

(+) All solid-state cell would simplify and lighten packaging

Sulfides offer large Eg and σLi> 10-3 S/cm

(-) Insertion compounds change volume on cycling, so cycle life of solid/solid interfaces is problematic

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• Solid-Electrolyte Separator(+) Would allow a lithium anode

Would block dendrites from a lithium anode or a Li/solid-electrolyte interface

Would allow alternative cathodes, e.g. air, S8, or Fe3+/Fe2+ (aq) flow through

(-) For an aqueous cathode, need an oxide separator: σLi(oxide) ≈ 10-4

S/cm fabricated thin and dense on a support; and not reduced by lithium


An Alkali-Metal/Aqueous Cathode Cell

No phase change takes place in the cathode. No catalyst is needed in the cathode. The cell is rechargeable. The cell works at room temperature. The cell works in the voltage range of 2.8 to 4.2 V.

Anode reaction: nA → nA+ + ne-; (A=Li or Na)Cathode Reaction: Mz+(aq) + ne- → M(z-n)+(aq);Overall reaction: nA + Mz+(aq) = nA+ + M(z-n)+(aq); (1≤ n < z).

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Organic electrolyte

Approach:


Selection of Aqueous Cathode with Existing Solid Electrolyte

Aqueous electrodes will depend on electrolyte and must have:1) proper redox potentials; 2) no side reactions; 3) good stability in water; 4) good reversibility; 5) reliable safety; 6) no toxicity and 7) low cost.

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Accomplishments:


A Lithium|Fe(NO3)3 (aq) Cell

The open circuit voltage of the battery is 3.99 V. Its initial discharge voltage is 3.74 V at a current of 0.5 mA.

After discharge Its initial charge voltage is 4.73 V at the current of 0.5 mA.

Hydrolyzation of Fe(III) results in precipitates of FeO(OH) for pH>2 and Fe(OH)3 for pH>4.8 when pH of the aqueous electrode solution increases with cell discharge.

0.0 0.2 0.4 0.6 0.8 1.02.5

3.0

3.5

4.0

4.5

5.0

5.5

∆V= 1.96 V

Pote

ntia

l (V)

Normalized Capacity

Discharge Charge

A

∆V= 0.95 V

0.0 1.0 2.0 3.0 4.0 5.00.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

FeO(OH) pH=2.0

pH

Concentration (mole L-1)

Fe3+

Fe2+

Fe(OH)3 pH=4.48

B

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First Cycle

Fe3+/Fe2+

Accomplishments:


Lithium| Fe(CN)63- (aq) Cells

No hydrolyzation of Fe(III) The theoretical voltage of the battery is 3.40 V. Its effective voltage with the commercial solid electrolyte distributes

between 3.33 V and 3.68 V. Different concentrations of the redox couple in the aqueous

electrode slightly affect the normalized discharge/charge curves. The battery shows a high coulombic efficiency.

0 5 10 15 20 250.00.10.20.30.4

2.02.53.03.54.04.55.0

Capa

city

(mAh

)

Cycle number

0.01 M Fe(CN)63-

0.1 M Fe(CN)63-

0102030405060708090100110

Coul

ombi

c ef

ficie

ncy

(%)

B

14

0.0 0.2 0.4 0.6 0.8 1.0 1.22.8

3.0

3.2

3.4

3.6

3.8

Pote

ntia

l (V)

Normalized capacity

0.01 M Fe(CN)63-

0.1 M Fe(CN)63-

∆V=0.35 V

Accomplishments:


Power Density and Reversibility of Li|Fe(CN)63- (aq) Cells

The cell demonstrates a maximum power density of 12.53 mW/cm2, which is competitive with a direct methanol fuel cell of similar active area.

Due to no cathode phase change in the charge/discharge, the cell shows a good reversibility. No capacity loss was observed over 1000 cycles.

0 2 4 6 8 10 120.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1.77 V

Pote

ntia

l (V)

Current density (mA cm-2)

12.53 mW/cm2

0

2

4

6

8

10

12

14

.

Powe

r den

sity

(mW

cm

-2)

D .

0 200 400 600 800 10000.15

0.20

0.25

0.30

0.35

0.40

0.45

Capacity Columbic Efficiency

Capa

city

(mA

h)

Cycle number

0

20

40

60

80

100

120

Coul

ombi

c Ef

ficie

ncy

(%)

15

Cycle 3.0 V – 3.75 V

Accomplishments:


Stability of Li|Fe(CN)63- (aq) Cells with Existing Electrolyte

0 1 2 3 4 5 6 7 80.00.51.01.52.02.53.03.54.04.55.0 3.0 2.5 2.0 1.5 1.0 0.5 0.2

Current density (mA cm-2)

Pote

ntia

l (V)

Time (Hours)

Potential Power density

0.1

2.8 V

0

1

2

3

4

5

6

7

8

Pow

er d

ensit

y (m

W c

m-2)C

0 100 200 300 400 500 6000

-100

-200

-300

-400

-500

-600

RSERF

354.89 Hz

2.51 Hz19.95 KHz

Fresh cell

Z'' (Ω

cm

2 )

Z' (Ω cm2)

1 MHz

RS RInt

A

0 100 200 300 400 500 600 700 8000

-100

-200

-300

-400

-500

-600

-700

-800

0.01 Hz

446.68 Hz

22.39 KHz1 MHz

Z'' (Ω

cm

2 )

Z' (Ω cm2)

After deep discharge

RsRF RSE RInt

C A C

RS (solution) 42.46 43.79

RF (charge transfer) 120.52 115.62

RSE(solid electrolyte) 160.24 237.84

RInt(interface) 143.34 346.33

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Rint → RSE afteraging uncycled for 10 h

Accomplishments:


Rechargeable Lithium|Cathode-Flow Battery (RLCFB)

The aqueous cathode in a flow-through mode can be individually stored in a “fuel” tank, which reduces the volume of the battery and increases the design flexibility of the battery structure.

Recycling of aqueous cathode can match the large capacity of lithium metal.

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Accomplishments:


Behavior of RLCFB

The maximum power density of the battery with existing electrolyte is about 17 mW/cm2.

Flow rates of the aqueous cathode don’t influence significantly the power density of the battery.

Development of a thinner solid-electrolyte separator with a higher Li+-ion conductivity would provide commercially viable room-temperature EES for energy sources alternative to fossil fuels.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.03.20

3.25

3.30

3.35

3.40

3.45

3.50

3.55

3.60

3.65

Volta

ge (V

)

Time (Hour)

0.41 ml/min 0.29 ml/min 0.16 ml/min 0 ml/min

0 2 4 6 8 10 12 14 160.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Volta

ge (V

)

Current density (mA/cm2)

0.41 ml/min 0.29 ml/min 0.16 ml/min 0 ml/min

0

2

4

6

8

10

12

14

16

18

Powe

r den

sity

(MW

/cm

2 )

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Accomplishments:


Summary

The study demonstrates the feasibility of a Lithium|water battery utilizing lithium metal as anode and a redox couple soluble in aqueous solution as the cathode.

This new strategy represents a third-generation lithium-ion battery promising lower cost than the conventional lithium-ion rechargeable battery, safe operation, and having a columbic efficiency and voltage greater than that of a Li/air battery with, in principle a comparable capacity.

A flow-through mode of the aqueous cathode can provide a full and efficient match of the capacity of a lithium-metal anode. The flow of the aqueous solution continuously brings heat out of the battery system and keeps the battery working near a mild condition.

Flow rates of the aqueous cathode in the study don’t influence significantly the power density of the battery.

The demonstrated power output is limited by the commercially available solid electrolyte separating an organic-liquid or polymer anolyte and the aqueous cathode; the fabrication of a superior solid electrolyte is clearly needed.

The new strategy promises to be applicable to both the electric-vehicle market and the problem of electrical energy storage for the grid.

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Future Work

By stabilizing the existing electrolyte against degradation, which we have shown to be due to the presence of Ti(IV), we will obtain data on the specific capacity versus molar fraction of the Fe(III)/Fe(II) couple in the cathode solution and how capacity is retained at higher discharge/charge rates.

We will obtain data on the ability of seals to prevent water crossover into the anode compartment and whether a lithium/solid-electrolyte solid-solid interface can be maintained over a long cycle life.

We will explore different cathode current-collector configurations.

Alternative solid electrolytes will be identified and their fabrication into dense, durable films will be explored.

The use of a Na rather than a Li anode with a Na+-ion solid electrolyte will be investigated.

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Documents

SOLID ELECTROLYTE BATTERIES - Department of Energy · The University of Texas at Austin SOLID ELECTROLYTE BATTERIES John B. Goodenough and Yuhao Lu. Texas Materials Institute. The