Aqueous Rechargeable Lithium Batteries (ARLBs) of High Energy Density

Prof. Dr. Yuping Wu

New Energy and Materials Laboratory (NEML), Department of Chemistry,

Fudan University, Shanghai 200433

Tel/Fax: +86-21-5566 4223 Email: wuyp@fudan.edu.cn

@ 6th US-China Electric Vehicles and Battery Technology Workshop, Boston

23-24 August, 2012

Motto of NEML

Electrochemical technologies 4E + E

Energy problem Environmental pollution

Enjoy life

Solve Reduce

To cultivate Elites for the society.

1. Chemical Power Sources • Supercapacitors • Polysulfide bromide battery (PSB) • Zn/Br battery • Vanadium redox couples (VRC) • Sodium sulfur battery (Na/S) • Lead acid battery • Metal-air battery • Ni-MH • Lithium ion battery

• Safety • Rate capability • Energy density • Energy efficiency • Cycling life • Maintenance • Capital cost for kWh • Per-cycle cost

• Aqueous rechargeable lithium battery (ARLB) • …… 2nd Symposium on Energy Storage and Power Batteries, Chengdu, 11-14 Nov.,

2007

Characteristics of lithium ion batteries: • High output voltage (average 3.6V) and power • High energy density (UR18650: >500 Wh/dm3, >200Wh/kg) • Low self discharge (<10%/month) • No memory effect • Long cycle life (>1000 times) • High rate capability (1C) • High coulomb efficiency (near 100% except in the 1st cycle) • Easy to measure the residual capacity • Maintenance free • No environmental pollution (green battery) • Wide work temperature (-25 - +45oC, extended to –40 – 70oC)

Lithium Ion Batteries

Main Materials for Lithium Ion Batteries

• Anode material • Cathode material • Electrolyte • Separator

Anode Cathode

Electrolyte

Separator

Inner safety

Energy Storage

Safety during Abuse Field Failure – Manufacturing defects • Loose connection, separator damage, foreign debris • Can develop into an internal short circuit • Can lead to overheating and thermal runaway Abuse Failure – Mechanical • crush, nail penetration – Electrical • short circuit, overcharge – Thermal • thermal ramp, simulated fire

A123: PHEV (Jun. 2008)

(April. 2011)

One conclusion @5th China-U.S. Electric Vehicle and Battery Technology Workshop

• Safety & reliability for lithium ion batteries is the challenging problems for electric vehicles.

• Gel lithium ion batteries (GLIBs) is surely the true choice as power source for EVs.

GMs: Self-distinguishing

Safety time: Another importance

Full charge and then put on electric oven: at least 1 min and 10 seconds (even for C//LiCoO2) to escape when EVs are on fire.

Li//Air

• Conductors of low ionic conductivity • Low stability: reaction with Li2O2 • Low O2 solubility • Low Li2O2 solubility • Narrow temperature • High overpotentials • Low energy efficiency • Low practical energy density • Sensitive to the environment • … …

Challenging problems

Prof. Deyang Qu @5th China-U.S. Electric Vehicle and Battery Technology Workshop, 17-18 April, 2012

Li//S • Li ??? Nobody should forget the story of MoLi

Company (Li//MoS2).

• MoS2 is more reliable than S. • Lithium dendrite is the main safety issue instead of S. • Low volumetric energy density.

Some facts:

There is still quite some distance to go.

New Power sources

Cheap: Lead acid has the largest market

Green: The ultimate goal of electrochemists

Neutral aqueous solutions.

Power density: Very high

What is ARLB ?

• Lithium intercalation compound(s) as one or both electrodes

• Redox reactions instead of absorption/ desorption

• Aqueous lithium-containing solution as electrolyte

Definition:

Why not called as aqueous lithium ion batteries: Misunderstanding: Aqueous to replace organic ??? Scope: Very narrow

W. Li, J. R. Dahn, D. Wainwright, Science, 264, 1115 (1994).

Poor cycling.

LiMn2O4//VO2(B)

2. Aqueous rechargeable lithium battery (ARLB)

Possibility and availability.

J. Glanz, Science, 264, 1084 (1994).

Comments

Since our first publication on ARLBs in Angew. Chem. Int. Edi. in 2007, Stanford Univ., Kyushu Univ. and the like show great interest.

Our reply: not “maybe” but “sure”.

2.1 Cathode: LiCoO2

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

3.83V

Scan rate 0.1mV/s

Lithium InsertionLithium Extraction

Cur

rent

(mA)

Potential (V)

4.13V

4.21V

4.08V

4.14V4.03V

0.4 0.6 0.8 1.0 1.2 1.4-10

-5

0

5

10

15

0.71V0.90V

1.01V

1.06V

Curre

nt (m

A)

Potential (V)

0.6mV/s

0.87V

0.95V

Lithium Extraction

Lithium Insertion

(a) In saturated Li2SO4 aqueous (b) In organic LIB 315

Similar behavior including phase transitions. DLi+ = 1.649 x 10-10 cm2/s

Wu et al., Angew. Chem. Int. Ed., 46, 295 (2007); Electrochim. Acta, 52, 4911 (2007).

De-intercalation and intercalation of LiCoO2 in aqueous and organic solutions.

Nanostructured LiCoO2

LiCoO2 from traditional solid-state reaction in aqueous electrolytes: Results from Stanford University.

Very good charge-discharge behavior for high power density.

Full charge: < 1 min.

Our nano LiCoO2

Wu et al., Electrochem. Commun. 11 (2010) 1524.

Fast kinetics

(a)In organic LIB 315 (b) In 2 M Li2SO4 aqueous

LiMn2O4: cheap

3.2 3.4 3.6 3.8 4.0 4.2 4.4-20

-15

-10

-5

0

5

10

15

20

0.1 mV s-1 0.5 mV s-1

3.94V

Scan rate: 2 mV s-1

Lithium insertion

Lithium extraction

Curre

nt (m

A)

Potential (V vs Li+/Li)

4.19V4.07V

4.08V

(a)

Similar intercalation and deintercalation behavior in organic and aqueous electrolytes. Satisfactory at high scan rate, indicating great promise for application at high current density for aqueous electrolyte.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6-0.12

-0.08

-0.04

0.00

0.04

0.08

0.12

Curre

nt (A

)Potential (V vs SCE)

1 mV s-1 2 mV s-1

4 mV s-1

6 mV s-1

8 mV s-1

(b)

Wu et al., Funt. Mater. Lett., 3 (2010) 151.

Fast kinetics

(a) (b)

200 nm200 nm

(c)

20 30 40 50 60 700

100200300400500600700

(d) Solid LiMn2O4

Porous LiMn2O4

Inte

nsity

(a. u

.)

2-Theta (degree)

PS template (1) Macroporous

(2) Nanograin (3) High crystallinity Wu et al., Energ. Environ. Sci., 2011, 43985 (Feature article).

(a) Solid-LiMn2O4 (b) Porous-LiMn2O4

0.2 0.4 0.6 0.8 1.0 1.2

-0.010

-0.005

0.000

0.005

0.010

0.015 a: Solid LiMn2O4

Curre

nt (A

)

Potential (V vs. SCE)

0.5 mV/s 1 mV/s 2 mV/s 3 mV/s 5 mV/s

0.2 0.4 0.6 0.8 1.0 1.2

-0.04

-0.02

0.00

0.02

0.04b: Porous LiMn2O4

Curre

nt (A

)

Potential (V vs. SCE)

1 mV/s 5 mV/s 10 mV/s 15 mV/s 20 mV/s

CVs in 0.5 mol l-1 Li2SO4 aqueous solution.

Electrode: 80% active material, 10% conductive agent and 10% binder.

Ultra-fast kinetics

5 6 7 8 9 10 11 120

1

2

3

4

5

6 Solid LiMn2O4

Porous LiMn2O4

-Z'' (

Ohm

)

Z' (Ohm)0 50 100 150 200 250

0.2

0.4

0.6

0.8

1.0 Porous LiMn2O4

Pote

ntia

l (V

vs. S

CE)

Specific capacity ( mAh g-1)

3rd2nd1st

Solid LiMn2O4

3rd2nd1st

The transportation process in porous LiMn2O4 electrode will be more facile.

Porous LiMn2O4: 118 mAh/g

Solid LiMn2O4: 85 mAh/g

Fig. Nyquist plots by using Ni mesh as the counter electrodes.

Fig. Charge-discharge curves at 100 mA/g for the initial 3 cycles.

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48

20

40

60

80

100

120

Unit: mA g-1

Porous LiMn2O4

Solid LiMn2O450 50

100009000

80007000

60005000

40003000

20001500

1000500300200

Spec

ific c

apac

ity (m

Ah g

-1)

Cycle number

Open: chargeSolid: discharge

0 50 100 150 2000.2

0.4

0.6

0.8

1.0

1.2

Specific capacity (mAh g-1)

200 mA g-1

500 mA g-1

1000 mA g-1

10000 mA g-1

5000 mA g-1

(a) Solid LiMn2O4

Pote

ntia

l (V

vs. S

CE)

0 50 100 150 200 2500.2

0.4

0.6

0.8

1.0

1.2 200 mA g-1

500 mA g-1

1000 mA g-1

5000 mA g-1

10000 mA g-1

Specific Capacity (mAh g-1)

(b) Porous LiMn2O4

Pote

ntia

l (V

vs. S

CE)

Fig. Charge-discharge at different current density.

Fig. Capacity at different current density.

In the case of porous LiMn2O4, capacity retention is 76% at the charge current density of 10000 mA/g.

0 5 10 15 20 25 30 35 40

0.2

0.4

0.6

0.8

1.0

10000 mAg-1

200 mA g-1

Capacity: 118 mAh g-1

Pote

ntia

l (V

vs. S

CE)

Time (min)

0 20 40 60 80 100 120 140

0.2

0.4

0.6

0.8

1.0

Pote

ntia

l (V

vs. S

CE)

Specific Capacity (mAh/g)

700050003000

1000

10000 mA/g

100 mA/g

500

The discharge curves of porous when it was fully charged at 100 mA/g): Capacity retention of 95% at 10000 mA/g.

Charge at 10000 mA/g and then kept at 1.29 V (NHE) until current goes to 100 mA/g.

Full charge: < 2.4 mins.

Porous LiMn2O4

Ultra-fast kinetics: much faster than in organic electrolytes.

0 2000 4000 6000 8000 100000

30

60

90

120

150

Porous LiMn2O4

Solid LiMn2O4

Spe

cific

cap

acity

(m

Ah

g-1)

Cycle number

(b)

Excellent cycling behavior

100 nm100 nm

TEM of porous LiMn2O4 after 10000 cycles.

Stable morphology and crystal structure after 10000 cycles.

Good crystal, nano grain and porous structure No acid: pH ~7

Oxygen: not removed

Nanochain LiMn2O4: Super-fast charge capability

0 20 40 60 80 100 1200.0

0.2

0.4

0.6

0.8

1.0

1.2

Pote

ntia

l / V

vs.

SCE

Capacity(mAh/g)

500mA/g charge 500mA/g discharge 1000mA/g charge 1000mA/g discharge 5000mA/g charge 5000mA/g discharge 10000mA/g charge 10000mA/g discharge

0 10 20 30 400.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.5C discharge

150C charge

92.6mAh/g

Pote

ntia

l / V

vs.

SCE

Time / min.

84.1%

SEM

Charge/discharge curves at different current densities

Super-fast charge performance

Wu et al., Electrochem. Commun., 13 (2011) 205.

24 seconds: 84.1%

NEML, Fudan Uni.

LiMn2O4 nanorod : Super-fast charge capability

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

Curre

nt /

APotential / V vs.SCE

Scan rate: 1 mV/s; 5 mV/s; 10 mV/s; 15 mV/s; 20 mV/s; 30 mV/s; 50 mV/s; 100 mV/s; 150 mV/s

(a)

SEM

Charge/discharge curves at different current densities

Super-fast charge kinetics: 40 sec (90%)

Wu et al., Electrochem. Commun., 13, 1159 (2011).

0 20 40 60 80 100 1200.00.10.20.30.40.50.60.70.80.91.01.11.21.3

Charge and discharge current:

Pote

ntial

/ V

vs.S

CE

Capacity / mAh/g

500mA/g 1000mA/g 5000mA/g 10000mA/g

(b)

CVs at different scan rate

2.2 Anode: PPy@(V2O5+CNTs)

SEM micrograph of the virginal hybrid of V2O5 with MWCNTs and TEM micrographs of the coated hybrid.

Electrochemical performance of the virginal and the coated hybrids and the prepared ARLB: (a) cyclic voltammograms, (b) charge and discharge curves, (c) charge and discharge curves of the ARLB together with those of LiMn2O4 and the coated hybrid, and (d) cycling behavior.

Wu et al., J. Mater. Chem., 2012, 22, in press

Anode: PPy@MoO3

-0.9 -0.6 -0.3 0.0 0.3 0.6 0.9 1.2

-0.003

-0.002

-0.001

0.000

0.001

0.002

0.003

0.004

-0.75 V

LiMn2O4

Cur

rent

/ A

Potential / V vs. SCE

Nanocomposite of MoO3 with PPy coating

(a) Scan rate: 1 mV/s

-0.60 V

-1.0 -0.8 -0.6 -0.4 -0.2 0.0-0.02

-0.01

0.00

0.01

0.02

0.03Nanocomposite of MoO3 with PPy coating

Curre

nt /

A

Potential / V vs. SCE

1 mV/s 5 mV/s 10mV/s 30 mV/s 50 mV/s 80 mV/s 100 mV/s

(b)

50 nm50 nm20 nm20 nm

8. 44nm

100 nm100 nm

(a)

(c)

(b)

(d)

PPy@MoO3//LiMn2O4

0 50 100 150 200 250-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Vol

tage

/ VDischarge

Charge

DischargeCharge

Discharge

LiMn2O4

MoO3Pote

ntia

l / V

vs.

SCE

Capacity / mAh/g

ARLB: MoO3//LiMn2O4 (a)

Charge

0 20 40 60 80 100 120 140

20

40

60

80

100

Coulombic efficiency for the ARLB from the nanocomposite

Cycling of the nanocomposite//LiMn2O4

Cycling of the virginal MoO3//LiMn2O4

Cycle number

Coul

ombi

c ef

ficie

ncy

/ %

(b)

0

20

40

60

80

100

120

140 Capacity / mAh/g for LiM

n2 O

4

0 1000 2000 3000 4000 5000 60000

10

20

30

40

50

Ener

gy d

ensit

y / W

h/kg

Power density W/kg

Nanocomposite/Li2SO4/LiMn2O4

Virginal MoO3/Li2SO4/LiMn2O4

(c) The energy density of this ARLB is 45 Wh/kg (lower than the estimated value, about 55 Wh/kg) at 350 W/kg and even maintains at 38 Wh/kg at 6 kW/kg. This kind of excellent rate capability can be compared with supercapacitors.

Wu et al., Energy Environ. Sci., 5, 6909 (2012).

(Top 10 most-read EES article)

Super-fast: < 36 sec

Comparison of Filling (charge) Time

Filling gasoline 1-3 mins (Full)

Filling natural gas 3-5 mins (full, fast)

Lithium ion batteries

> 10 min (<80%)

ARLBs < 1 min (>90%)

Note: For average size vehicle.

2.3 Advantages of ARLBs Easy to produce Good availability of lithium salts High ionic conductivity, about 1-2 orders of magnitude higher than organic electrolyte, suitable for charge and discharge at high rate High power density Good safety, no combustibility or explosion Low cost for production due to no requirements on the content of moisture Low requirements on separators especially the shut-down performance Friendly to environment, completely GREEN Satisfactory energy density 40- 90 Wh/kg for the total electrodes Super-fast charge capability Excellent cycling behavior

Good promising for energy storage, HEVs, assistance for EVs and range-extenders.

3. New ARLBs: EVs for long distance

P.G. Bruce et al., Nat. Mater., 11, 19 (2012).

??? No idea so far

High voltage cathode ??? Li-rich cathode ??? Si anode ???

Li metal is not stable in water !!! Li + H2O = LiOH + H2

Fire(火)

Earth(土)

Wood(木)

Metal (金)

Water(水)

Incompatible Compatible

Traditional Theory of the Five Elements

LiMOx

Lithium metal

To make fire compatible with water

Water(水) Fire(火) Wood(木)

Lithium metal GPE + LISICON LiMn2O4

Target: Polymers No LISICON (earth)

ARLBs of High Energy Density

2.5 3.0 3.5 4.0 4.5 5.0

-0.2

-0.1

0.0

0.1

0.2

0.3

Li+ intercalation into LiMn2O4

Cur

rent

/ m

A

Potential / V vs. Li+/Li

Li+ deintercalation from LiMn2O4

CN Patent Application No: 201210195152.2, PCT is under way.

ARLB of Li//LiMn2O4

0 30 60 90 120 1502.5

3.0

3.5

4.0

4.5

Volta

ge /

V

Capacity / mAh/g

Charge Discharge

(a)

0 5 10 15 20 25 3020406080

100120140160180200220

Cycle number

Cap

acity

/ m

Ah/

g

20

40

60

80

100

Cou

lom

b ef

feci

ency

/ %

(b)

Fast kinetics: Small overpotential High energy/power

efficiency: >95% (very rare) Good cycling: No evident capacity

fading Stable lithium metal: No chance of lithium

dendrite

High energy density

ARLB Calculated energy density

50% utilization based on LIBs

Possible practical energy density

Li//LiMn2O4 446 Wh/kg 50% > 220 Wh/kg

Li//NCM > 600 Wh/g 50% > 300 Wh/kg

In aqueous electrolyte: At least 3 times thicker electrode pellets.

Advantage of the New ARLBs Good safety and reliability: an effective (close contact

with the anode) cooling system (aqueous) Benign to environment: much green (no LiPF6) High energy density: > 600 Wh/kg based on the mass of

the electrode materials, and > 300 Wh/kg for practical value

High coulomb efficiency: near 100% except for the initial cycles

Fast redox kinetics for the electrodes: small overpotentials & superfast charge

High energy/power efficiency: > 95% No memory effects Excellent cycling life: > 10000 cycles Low cost … …

4. Summary

• Nanomaterials greatly promote the development of ARLBs (aqueous rechargeable lithium batteries) including reversible capacity, rate capability and cycling behavior.

• New designed ARLBs open a great future for energy

storage including EVs and smart grids in the near future.

• Social sciences are good to develop natural sciences: life enjoyment can lead to new ideas.

We are developing new rechargeable aqueous battery systems with energy density > 500 Wh/kg (estimated practical value).

Acknowledgment

• National Basic Research Program of China (973 Program No: 2007CB209702)

• Natural Science Foundation Committee of China

• Ministry of Science and Technology of China • Science and Technology Commission of

Shanghai Municipality • Alexander von Humboldt Foundation

(Partnership Program) • Sanyo Chemical

Financial sponsors and collaborators:

Twice Study Tours to Shanghai Expo (2010) for our NEML

Study Tour to Xi’An (2011) (The top of Hua Mountain to watch sunrise)

Thanks for your kind attention !