In situ Characterizations of New Battery Materials and the ... · In situ Characterizations of New Battery Materials and the Studies of High Energy Density Li-Air Batteries Xiao-Qing

In situ Characterizations of New Battery Materials and the Studies of High Energy Density Li-Air Batteries

Xiao-Qing Yang and Kyung-Wan NamBrookhaven National Lab. (BNL)

May 9-13, 2011

ES059

This presentation does not contain any proprietary, confidential, or otherwise restricted information

2011 DOE Hydrogen Program and Vehicle Technologies Annual Merit Review and Peer Evaluation Meeting

Washington, DC, May 9-13

1

OverviewTimeline

Start: 10/01/2009 Finish: continued Continued

Barriers addressed Li-ion and Li-metal batteries with long calendar and cycle life Li-ion and Li-metal batteries with superior abuse tolerance To reduce the production cost of a PHEV batteries

Budget Funding received in FY10

DOE: $650k Funding received in FY11

DOE: $650k

Collaborators University of Massachusetts at Boston Dow Chemical GM R&D Center Oakridge National Lab. (ORNL) University of Tennessee Argonne National Lab. (ANL) SUNY Binghamton SUNY Stony Brook SUNY Buffalo Korean Institute of Science and Technology (KIST) Beijing Institute of Physics Hydro-Québec (IREQ)

2

Objectives of This Project To determine the contributions of electrode materials changes, interfacial

phenomena, and electrolyte decomposition to the cell capacity and power decline. To develop and apply synchrotron based in situ X-ray techniques to study materials

in an environment that is close to the real operating conditions. To screen and study the potentially low cost and high energy density materials such

as Li2MnO3-LiMO2 and LiFe1-yMnyPO4. To synthesize and characterize high voltage cathode and high voltage electrolytes

for high energy density lithium batteries for plug-in hybrid electric vehicles (PHEV). To carry out fundamental studies of high energy density Li-Air batteries and gas

diffusion electrode materials for Li-air batteries. To design, synthesize and characterize new electrolyte and electrolyte additives to

increase the O2 solubility and/or with capability to dissolve Li2O and Li2O2 oxides for Lithium-air batteries.

To develop new diagnostic tools for battery studies. To identify and investigate the new battery materials with low cost potential to meet

DOE goals.3

Milestones

4

Month/Year Milestones

Apr/11Complete soft X-ray absorption spectroscopy (XAS) studies of Li1.2Ni0.2Mn0.6O2

cathode materials during electrochemical cycling. Completed.

Apr/11Complete the studies of carbon structure effects on the electro-catalysis performance of air cathode in Li-air cells. Completed.

Sep/11

Complete in situ X-ray diffraction studies of manganese doped lithium iron phosphate (LiFe1-yMnyPO4) cathode materials with mesoporous structure in comparison with large particle sized cathode during electrochemical cycling. On schedule.

Sep/11Complete the studies of the effects on the improvement of discharge current density by increasing the solubility of oxygen in Li-Air electrolytes. On schedule.

Approaches

5

In situ XAS and XRD studies of new electrode materials such as LiFe1-yMnyPO4 and high capacity Li1.2Ni0.2Mn0.6O2 during electrochemical cycling to carry out the diagnostic studies to improve the energy density and cycle life of Li-ion batteries.

Soft XAS on the L-edges of Mn and Ni to distinguish the difference between the surface and the bulk structural changes caused by charge-discharge cycling for new cathode materials such as Li1.2Ni0.2Mn0.6O2.

In situ and ex situ transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) to study the structural changes of electrode materials with high location specification and spatial resolution.

Electrochemical studies of gas diffusion electrode (GDE) for Li-Air batteries. Improve the performance of the GDE by surface modification. Develop new electrolyte with higher O2 solubility to increase the discharge current

density of Li-Air batteries. Design and synthesis of new electrolyte system with capability to dissolve Li2O and

Li2O2, and/or high solubility of O2 for lithium-air batteries.

Technical Accomplishments

6

Developed new in situ XRD to study cathode materials for Li-ion batteries during chemical delithiation.

Completed combined in situ hard XAS and ex situ soft XAS studies on high energy Li1.2Ni0.2Mn0.6O2 cathode materials during charge-discharge cycling. Important information about the roles of Mn cations was obtained.

Completed in situ XAS and XRD studies on mesoporous LiFe1-yMnyPO4 (0.0≤y≤0.8) cathode materials during charge-discharge cycling. The effects of particle size and morphology on the phase transition behavior and performance of Li-ion cellshave been studied.

Modified the surface of carbon materials for gas diffuse electrode (GDE), which significantly improved the discharge capacity of the Lithium-Air cell.

Developed novel new electrolyte which can increase the solubility of O2dramatically. The discharge rate of the Lithium-Air cell using this new electrolyte is increased more than one order of magnitude than the conventional electrolytes.

Developed a family of new boron based additives with good SEI formation capability and anion receptor functionality for lithium battery electrolyte (US patents were filed in 2010). Designed and synthesized new solvents for lithium battery electrolytes.

New in situ XRD techniques during chemical delithiation

7

X ray beam path

Cotton

LiFePO4 powder

NO2BF4/CH3CN solution

Connected with waste container

Connected with pump

Reaction: LiFePO4 + NO2BF4---> FePO4+LiBF4 +NO2

X ray beam path

Cotton

LiFePO4 powder



Connected with pump


X ray beam path

Cotton

LiFePO4 powder



Connected with pump


X ray beam path

Cotton

LiFePO4 powder



Connected with pump

X ray beam path

Cotton

LiFePO4 powder



Connected with pump


Inte

nsity

0

127000

Tim

e (m

in)

0

48

(b)

2θ(λ=0.7748 A)o

Inte

nsity

0

127000

Tim

e (m

in)

0

48

(b)

Inte

nsity

0

127000

Tim

e (m

in)

0

48

(b)

Inte

nsity

0

127000

Tim

e (m

in)

0

48

Inte

nsity

0

127000

Tim

e (m

in)

0

48

Inte

nsity

0

127000

Inte

nsity

0

127000

Tim

e (m

in)

0

48

Tim

e (m

in)

0

48

(b)

2θ(λ=0.7748 A)o

2θ(λ=0.7748 A)o

New in situ XRD techniques during chemical delithiation have been developed tostudy the structural changes of electrode materials for lithium-ion batteries.

Implication?

Submitted to Chemical Communications

Higher energy density and lower cost cathode materialsThe phase transition in LiFe1-yMnyPO4 is not fully understood because it mainly depends on the particle size, Mn content et al.

8

Mesoporous LiFe1-yMnyPO4 (0≤y≤0.8)

LiFe1-yMnyPO4: High speed ball milling and citric acid

Motivation

Results

Typical TEM image

-20 0 20 40 60 80 100 120 140 160 1802.0

2.5

3.0

3.5

4.0

4.5

5.0

0.1C

5C 1C 0.1CVota

ge(V

vs.

Li+

/Li)

Capacity(mAh/g)

5C 1CLiFe0.6Mn0.4PO4

-20 0 20 40 60 80 100 120 140 160 1802.0

2.5

3.0

3.5

4.0

4.5

5.0

0.1C

5C 1C 0.1CVota

ge(V

vs.

Li+

/Li)

Capacity(mAh/g)

5C 1CLiFe0.6Mn0.4PO4

unpublished

9

In situ XAS of mesoporous Li1-xFe0.6Mn0.4PO4 during cycling

0 10000 20000 30000 40000 500002

3

4

550000 40000 30000 20000 10000 0

Fe3+

Volta

ge(V

)

Time(s)

Fe2+

Fe3+Fe2+

Mn3+Mn2+

Mn2+ Mn3+S1

S104

S76

S26

S32

S70

S53

1st cycle1st cycle

7110 7120 7130 7140

1st cycle

Norm

alize

d in

tens

ity (a

.u.)

S104

S70

S34

S02

Fe K-edge

S32

S52

S54

S72

Char

ging

Disc

harg

ing

6540 6550 6560

Norm

alize

d in

tens

ity (a

.u.)

1st cycle

S103

S75

S27

S25S01

S53

S55

S77

Char

ging

Disc

harg

ing

Mn K-edge

Energy (eV)

XANES

Reversible redox reactions of Fe2+/Fe3+ and Mn2+/Mn3+ at low voltage (~3.5V) and high voltage (~4.0V) plateaus during 1st cycle.

Simultaneous Fe2+/Fe3+ and Mn2+/Mn3+ redox reactions at the sloppy voltage region (transition region). Related to the solid-solution (single phase) region.

0 10000 20000 30000 40000 500002

3

4

550000 40000 30000 20000 10000 0

Vol

tage

( V

)

Fe3+Fe2+

Mn3+Mn2+

Mn3+

Time(s)

S132

S210S106

S138

Mn2+

2nd cycle

Fe2+ Fe3+

S174

S168

10

2nd cycle

In situ XAS of mesoporous Li1-xFe0.6Mn0.4PO4 during cycling

Quite reversible Fe and Mn K-edge shifts at both low voltage (~3.5V) and high voltage (~4.0V) plateaus at 2nd cycle suggesting very reversible redox reactions of Fe2+/Fe3+ and Mn2+/Mn3+.

Well agreed with highly reversible Li extraction/ insertion behavior of the mesoporous LiFe0.6Mn0.4PO4 during cycling. Good cyclability!

XANES

7110 7120 7130 7140

Norm

alize

d in

tens

ity (a

.u.)

2nd cycle

S208

S168

S156

S106 S138

S140

S158

S170

Char

ging

Disc

harg

ing

Fe K-edge

6540 6550 6560

Norm

alize

d in

tens

ity (a

.u.)

S171

S209

S137

S139

Energy ( eV )

S105

S155

S157

S173

Mn K-edge

Disc

harg

ing

Char

ging

2nd cycle

11

Comparative study of crystal structural changes of Li1-xFe0.6Mn0.4PO4with and without mesoporous structure by in situ XRD during charge

28 30 34 36 5 4 3

0

4

8

1290

73

55

37

19

1

Inte

nsity

(arb

. uni

t)

I-PI-PI-PI-P

(211

)

(131

)

(211

)

(131

)

(200

)

(121

)

O-P

F-P

O-P

F-P(2

00)

(121

) Al

Scan numbers

Char

g tim

e (h

our)

28 30 32 34 36 5 4 3

0

5

10

15

20

25

11

101110

89

5947413323

1

Inte

nsity

(arb

. uni

t)

2θ (λ=1.54)

Char

ge ti

me(

hour

)

Voltage(V vs Li+/Li)

With mesopores

Without mesopores

For the sample with mesoporous structure, a significant phase transition delay was observed: the second phase appear at the end of the plateau, rather than at the beginning. The transition to the third phase is almost completed at the end of charge at 5V.

For the sample without mesoporous structure, no significant phase transition delay was observed: the second phase appear at the beginning of the plateau. The transition to the third phase is not completed at the end of charge at 5V.

14 15 16 17 18 19 5 4 3 2

0

5

10

1589

76

60

30

101

Inte

nsity

(arb

. uni

t)

Scan numbers

Mesoporous sample

Disc

harg

e tim

e(ho

ur)

24 26 28 30 32 34 36 4 3 2

0

4

8

12

16

M4F6 no acid 650 50oC C/20176

164

152

140

1281161101

Inte

nsity

(arb

. uni

t)

2θ (λ=1.54)

Di

scha

rge

time(

hour

)

Voltage(V vs Li+/Li) 12

Comparative study of crystal structural changes of Li1-xFe0.6Mn0.4PO4with and without mesoporous structure by in situ XRD during discharge

With mesopores

Without mesopores

For the sample with mesoporous structure during discharge, the phase transition back to intermediate phase 2 and original phase 1 are quite reversible.

For the sample without mesoporous structure during discharge, the phase transition back to intermediate phase 2 and original phase 1 are not reversible at all. Large amount of sample still remain in the intermediate phase 2 at the end of discharge.

13

1st charge-discharge curves of Li1-xFe0.6Mn0.4PO4without mesoporous structure

Comparing with the Li1-xFe0.6Mn0.4PO4 with mesoporous structure created by citric acid during synthesis, the Li1-xFe0.6Mn0.4PO4 sample without mesoporous structure showed quite poor voltage profile and discharge capacity, indicating the low utilization of the active material during both charge and discharge.

0 20000 40000 60000 800002.5

3.0

3.5

4.0

4.5

5.080000 60000 40000 20000 0

1108959

47

413323

Volta

ge(V

)

Time(s)

1

152

116128

140

164173

M4F6 no acid 650 C/20

14

For LiFeyMn1-yPO4, with y=0.2, 0.4, 0.6, 0.8, two plateaus are observed and the length of second plateau increases with increasing y. Every second phase starts appearing at the end of the first plateau, where the voltage is rising rapidly. (cut off voltage = 4.5V)

15

In situ XRD of mesoporous Li1-xFe0.6Mn0.4PO4 withincreased cut off voltage to ~ 5.0V

By increasing charge voltage to 4.8 V, the third final phase (FP) was observed. In our early studies, only the original phase OP (original phase) and intermediate phase IP (Intermediate phase) were observed. `

28 30 36 5 4 3

0.0

0.4

0.8

1.2

I-PI-PI-PI-P

Inte

nsity

(a.u

.)

(211

)

(131

)

(211

)(131

)

(200

)

(121

)

O-P

F-P

O-P

F-P

(200

)(1

21)

X in

Li 1-

xFe 0.

6Mn 0.

4PO

4

O-P

I-P

O-P + I-P

F-P

28 30 36 5 4 3

0.0

0.4

0.8

1.2

I-PI-PI-PI-P

Inte

nsity

(a.u

.)

(211

)

(131

)

(211

)(131

)

(200

)

(121

)

O-P

F-P

O-P

F-P

(200

)(1

21)

X in

Li 1-

xFe 0.

6Mn 0.

4PO

4

O-P

I-P

O-P + I-P

F-P

O-P

I-P

O-P + I-P

F-P

2θ (λ= 1.54Å) Voltage (V)

16

Phase transition behaviors in mesoporous LiFe1-yMnyPO4(0≤y≤0.8) during charge

3

4

5

0.0 0.2 0.4 0.6 0.8 1.0

4

X in Li1-xFe1-yMnyPO4Volta

ge (V

)

3

4

3

4

5

3

4

50.0 0.2 0.4 0.6 0.8 1.0

Original Phase

Final Phase

Intermediate Phase

Volta

ge (V

)

LiFe0.8Mn0.2PO4

LiFePO4

LiFe0.6Mn0.4PO4

LiFe0.4Mn0.6PO4

LiFe0.2Mn0.8PO4

Both the intermediate phase and the final phase appeared a delay to the charge curve.

Their appearance is related to the regions where the voltage moves up sharply.

The higher the content of Mn, the wider the range of the intermediate phase

In situ XAS study of high energy Li1.2Ni0.2Ni0.6O2 cathode material

Charge-discharge current density = 0.11 mA/cm2 at room temp. Increase in the capacity Li1.2Mn0.6Ni0.2O2 cathode during initial a few cyclings. Why?

Combined in situ Ni & Mn K-edge and ex situ Mn L-edge XAS was used to study the chargecompensation mechanism and increasing capacity during initial cyclings.

17

2 3 4 5-0.01

0.00

0.01

0.02

0.03 1st cycle 2nd cycle 3rd cycle

dQ/d

V (A

h V-1

)Voltage ( V vs Li/Li+)0 50 100 150 200 250

2

3

4

5 1st cycle 2nd cycle 3rd cycle

Volta

ge (

V vs

. Li/L

i+ )

Capacity ( mAh g-1)

In collaboration with Dr. Kang at Argonne Nat’l Lab.

Charge-discharge curvesDuring in situ experiment

Increase in capacityduring cyclings


Ni valance in pristine Li1.2Mn0.6Ni0.2O2 is slightly over 2+.Mn valance in pristine Li1.2Mn0.6Ni0.2O2 is 4+.

18

In collaboration with Dr. Kang at Argonne Nat’l Lab.

8330 8340 8350 83600.0

0.6

1.2

1.8 Li1.2Ni0.2Mn0.6O2 (pristine)

Norm

alize

d in

tens

ity (

a.u.

)

Energy ( eV )

Li1.2Ni0.2Mn0.6O2= 0.5Li2MnO3 0.5LiNi0.5Mn0.5O2 (ideally Ni2+, Mn4+)

However, valance of Ni is slightly over 2+.

NiO(Ni2+)

LiNi0.8Co0.15Al0.05O2(Ni3+)6540 6550 6560 6570

0.0

0.6

1.2

1.8 Li1.2Ni0.2Mn0.6O2 (pristine) Li1.0Ni1/3Co1/3Mn1/3O2 (Mn4+)

Norm

alize

d in

tens

ity (

a.u.

)

Energy ( eV )

Mn valance = 4+.

Mn K-edgeNi K-edge


Clear Ni K-edge shift in a reversible manner during 1st cycle. More reduction in Ni beyond pristine state close to Ni2+ after 1st discharge.

However, Mn contribution to the charge compensation reaction after 1st charge remains unclear. Mn L-edge soft XAS to look at the surface!

19

2.02.53.03.54.04.55.0

6552

6553

6554

6555

Volta

ge (

V vs

. Li/L

i+ )

0 5 10 15 20

8343

8344

8345

8346 Ni K-edge

Ener

gy a

t 1/2

inte

nsity

( eV

)

Time ( h )

Mn K-edge

Ni2+/3+/4+ Activation of Li2MnO3 phase Ni4+/2+

??

1st charge 1st discharge

High

er o

xidat

ion

stat

e of N

i or M

n

8335 8340 8345 8350 8355

Li1.2Ni0.2Mn0.6O2 (pristine) After 1st charge After 1st discharge

Energy ( eV )

NiO(Ni2+)

LiNi0.8Co0.15Al0.05O2(Ni3+)

Pristine spectrum is identical to the Li2MnO3 (Mn4+) spectrum.

Mn4+ ions remain unchanged during 1st charge and then start to reduce slightly to Mn3+ below ~ 3.6V during 1st

discharge.Surface of particle is reduced from

Mn(4+)O2 to LiMn(3+)O2 and participate in charge compensation reaction during 1st discharge. 1st spectroscopic evidence !!

20

Ex situ Soft XAS study of Li1.2Ni0.2Mn0.6O2 during 1st cycle

Mn L-edges (EY detector) : Surface !!

635 640 645 650 655Energy ( eV )

Norm

alize

d In

tens

ity (

a.u.

)

#7: 2.0V

#6: 3.1V

#5: 3.6V

#4: 4.8V

#3: 4.6V

#2: 4.3V

#1: Pristine

Evolution of shoulder peak at low energy side

Peak shift to lower energy

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 100 200 300 400

Capacity, mAh/g

Voltage,

V

1

2 3 4

5

7

6

Quite reversible Mn3+/Mn4+

redox reaction becomes more pronounced especially at the surface of Li1.2Ni0.2Mn0.6O2during further cyclings.

Activation of Mn site at the surface occurs during initial cyclings. can explain increase in

capacity during cycling inpart.

21

Ex situ Soft XAS study of Li1.2Ni0.2Mn0.6O2 during cycling

635 640 645 650 655

Mn3O4

Mn2O3

Li2MnO3

Energy ( eV )

Norm

alize

d In

tens

ity (

a.u.

)#11: 2.0V#10: 4.8V

#9: 2.0V#8: 4.8V

#7: 2.0V#4: 4.8V

#1: Pristine Before 1st charge

1st charged 4.8V

1st discharged 2.0V

2nd charged 4.8V

2nd discharged 2.0V

6th discharged 2.0V

5th charged 2.0V

Quite reversible Mn3+/Mn4+ redox

reaction after several initial cycles!!

Mn L-edges (EY detector) : Surface !!

cycle

Mn3+/4+ active layer

Li1.2Ni0.2Mn0.6O2 Li1.2Ni0.2Mn0.6O2

When H in EC is replaced by the electron donating group CH3 in PC, the electrolyte lost SEI formation capability.

When the CH3 is replaced by electron withdrawing group CF3, the SEI formation capability is increased. 22

New solvents synthesized and studied to understand the effects of substitution groups on the SEI formation capability

O

O O

CF3CF3

O

O O

CF3CF3

O O

CF3CF3

O O

O

CF3

O O

O

CF3

O O

O

F

O O

O

F

O O

O

H

O O

O

CH3

0 100 200 300 400 500 600 700 800 900024

85.4%

Vota

ge(V

vs.

Li+

/Li)

Capacity(mAh/g)

024

87.6%

024

As solvent (R:DMC=1:1 in Volume)

83.6%

024024

Coulombic efficiency 90.1%

BTFPC:DMC

TFPC:DMC

MFPC:DMC

EC:DMC

PC:DMC

23

Electron withdrawing on ring opening

O

O

-2(CF3) -CF3 -CH2F -H -CH3Withdrawing Donating

-2(CF3) -CF3 -CH2F -H -CH3Withdrawing Donating

-2(CF3) > -CF3 > -CH2F > -H > -CH3Easy Difficult

Ring-opening reaction

-2(CF3) > -CF3 > -CH2F > -H > -CH3Easy Difficult

Ring-opening reaction

EC>> PC ~ γ-BLMacromolecules 2004, 37, 6755-6762

NH NH

O

Tetramethylene Urea (TeU)

NH NH

O

Tetramethylene Urea (TeU)

O O

O

CH3

O O

O

H

O O

O

R

24

Approaches and achievements on Li-air battery research

Li2O and Li2O2 deposition on the carbon electrode and filling up pores causing the premature passivation of the gas-diffusion-electrode . Surface modification.

Solubility of Li oxides. New additives.Oxygen solubility in non-aqueous electrolytes. New electrolytes.

-50 0 50 100 150 200 250 300 350 400 450

1.0

1.5

2.0

2.5

3.0 UMB10, non-coated UMB10, coated

Pote

ntia

l / V

vs

Li

Discharge Time / min

(1)

(2)

500mAh/g at 1mA/cm2

Formation of the Compact and dense surface Li oxides passivation film can be delayed by modifying the carbon surface with long chain functional groups.

Submitted to Carbon

25

Comparison of O2 reduction on Pt RDE and Pt micro disk electrode (with the great advantage in outside of the glove box operation)

5 times increase of O2 solubility was observed on both electrodes.

-0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

1 M LiPF6+PC 1 M LiPF6+PC+5% FTBA

Curre

nt /

nA

Potential / V vs Ag/AgCl

(B)

-0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0-7

-6

-5

-4

-3

-2

-1

0


Curre

nt / µA

Potential / V vs Ag/AgCl

(A)

On Pt RDE On Pt micro electrode

100 µm cavityFilled with activatedCarbon powder

Graphite or Hg contact

100 µm Pt

The performance of Li-air cell with new electrolyte is significantly improved.

0 5 10 15 20 251.5

2.0

2.5

3.0

3.5

4.0


Volta

ge /

V

Discharge Time / hours

2000mAg-1

26

Up to now, the discharge rate of Li-air cell is too low (about 0.1 mA/cm2). Using our new electrolyte with increased O2 solubility and mobility, almost 100 time higher discharge rate has been achieved, making it closer to the Li-ion battery level, which is feasible for practical application.

Electrode weight: 0.05 g (carbon)27

Collaborations with Other Institutions and Companies University of Massachusetts Lithium air battery.

Argonne National Lab. (ANL) In situ XAS study of high energy Li1.2Ni0.2Mn0.2O2 cathode material.

Oakridge National Lab. (ONL) & University of Tennessee In situ XRD technology development for Li-ion battery material research at NSLS.

Dow Chemical Corp. General Motor Corp.

Beijing Institute of Physics New electrolyte additives and olivine structured LiFe1-xMnxPO4 cathode materials.

Korea Institute of Science and Technology (KIST) Surface coated (e.g., ZrO2, AlPO4, and Al2O3) layered cathode materials.

Hydro-Québec (IREQ) Olivine structured LiMPO4 cathode materials.

SUNY at Stony Brook NMR study of olivine structured LiMPO4 cathode materials.

SUNY at Binghamton XAS and XRD study of olivine structured LiMPO4 cathode materials. 28

Planned work for FY 2011 and FY2012

29

Complete soft and in situ hard XAS study of high energy Li2MnO3-LiMO2 (M=Ni, Co, Mn, Fe)cathode materials during activation charge and multiple cycling.

Complete comparative in situ XRD and XAS studies of LiFe1-xMnxPO4 (x=0 to 1) cathodematerials with different particle size and morphology during chemical and electrochemicaldelithiations.

Develop and test the atomic layer deposition (ALD) surface coating on new cathodematerials.

Using time resolved XRD to study the thermal stability of ALD surface coated Li2MnO3-LiMO2 (M=Ni, Co, Mn, Fe) cathode materials during heating.

Further development of surface and interface sensitive techniques, such as soft x-rayabsorption, TEM, SAED, and electron energy loss spectroscopy (EELS) for diagnosticstudies on surface-bulk differences and phase transition kinetics of electrode materials.

In collaboration with UMASS at Boston, continue on the efforts to develop gas diffusionelectrode (GDE) with MnO2 catalyst for Li-air batteries. Start the preliminary studies of therechargeable lithium-air cells and in situ XRD and XAS on the GDE.

Develop new electrolyte systems to increase the solubility and mobility of O2 in theelectrolyte in order to increase the discharge rate of lithium air cells.

Summary

30

In the Multi Year Program Plan (MYPP) of VTP, the goals for battery were designed as: “Better energy storage systems are needed to expand the commercial markets for HEVs and to make PHEVs and EVs commercially viable. Specifically, lower-cost, abuse-tolerant batteries with higher energy density, higher power, better low-temperature operation, and longer lifetimes are needed for the development of the next-generation of HEVs, PHEVs, and EVs.” This ES059 program has been making progress towards these goals and will plan future works to achieve these goals.

In collaboration with ANL, and GM R&D Center, Li2MnO3-LiMO2 (M=Ni, Co, Mn) type high energy density cathode materials have been studied using combined in situhard XAS and ex situ soft XAS. The results of these studies provide useful information for improving the energy density and cycleability of high energy density Li-ion batteries.

In collaboration with Institute of Physics, CAS, the mesoporous LiFe0.6Mn0.4PO4cathode material are being studied by in situ XRD and XAS in comparison with the same composition without mesoporous structure. The results of these studies provide important information about the effects of meso-pores on the phase transition behavior and performance of this new cathode materials with low cost potential.

Summary (cont’d)

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Developed new in situ XRD to study cathode materials for Li-ion batteries during chemical delithiation.

Modified the surface of carbon materials for gas diffuse electrode (GDE), which significantly improved the discharge capacity of the Lithium-Air cell.

Developed novel new electrolyte which can increase the solubility of O2 dramatically. The discharge rate of the Lithium-Air cell using this new electrolyte is increased almost 100 times than the conventional electrolytes.

Developed a family of new boron based additives with good SEI formation capability and anion receptor functionality for lithium battery electrolyte (US patents were filed in 2010). Designed and synthesized new solvents for high voltage lithium battery electrolytes.

Collaborations with US industrial partners such as Dow chem. and GM, as well as with US and international research institutions (IOP in China, KIST in Korea) have been established. The results of these collaborations have been published or presented at invited talks at international conferences.

Documents

In situ Characterizations of New Battery Materials and the ... · In situ Characterizations of New Battery Materials and the Studies of High Energy Density Li-Air Batteries Xiao-Qing