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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
NO2BF4/CH3CN solution
Connected with waste container
Connected with pump
Reaction: LiFePO4 + NO2BF4---> FePO4+LiBF4 +NO2
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
NO2BF4/CH3CN solution
Connected with waste container
Connected with pump
X ray beam path
Cotton
LiFePO4 powder
NO2BF4/CH3CN solution
Connected with waste container
Connected with pump
Reaction: LiFePO4 + NO2BF4---> FePO4+LiBF4 +NO2
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
In situ XAS study of high energy Li1.2Ni0.2Ni0.6O2 cathode material
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
In situ XAS study of high energy Li1.2Ni0.2Ni0.6O2 cathode material
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
1 M LiPF6+PC 1 M LiPF6+PC+5% FTBA
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
1 M LiPF6+PC 1 M LiPF6+PC+5% FTBA
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
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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.
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