studies on the local state of charge (soc) and …5c 5c 2c 2c c/5 charge 85-7.5-7.5 discharge...
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Studies on the Local State of Charge (SOC)
and Underlying Structures in Lithium Battery Electrodes
Jagjit Nanda
Oak Ridge National Laboratory
This presentation does not contain any proprietary, confidential, or otherwise restricted information
DOE Annual Merit ReviewEnergy Storage
May 12th 2011Arlington VA
Project ID: ES106
2 Managed by UT-Battellefor the U.S. Department of Energy
OverviewTimeline
Project Start Date : 10/1/2010 (FY2011)Percentage Complete : 65%
BudgetFY 2010 : 230K(June Fin Plan : Capital request)
FY 2011 : 400K
BarriersCycle life and Capacity fade
Rate PerformanceSEI Stability
Surface Degradation and Structural changes
Collaborators/PartnersDr. S. K. Martha
Post Doctoral Researcher
Ford Motor Co.Dawn BernardiRaji ChandrasekaranAndy DrewsAnn O'NeillJeffrey Remillard
Toda IncMr. Toyoji Sugisawa
Non funding partners
3 Managed by UT-Battellefor the U.S. Department of Energy
Project Objectives
• Correlate local electrode and interfacial properties at sub-micron level to the macroscopic electrochemical performance .
• Investigate local inhomogenity, composition, structural changes during lithiation-delithiation of high energy lithium electrodes.
• Dynamical/in situ studies for spatio-temporal mapping of commercial electrodes subjected to stress/abuse.
4 Managed by UT-Battellefor the U.S. Department of Energy
Programmatic MilestonesTask 1: Electrode Fabrication and Electrochemical Testing
Subtask 1.1 : Electrochemical performance of Excess Lithia Compositions from Toda Inc. Progress/Status : Work in progress (70% complete)
Task 2: Ex-situ SoC analysis of commercial and Laboratory Fabricated High Energy Cathodes Subtask 2.1 Local SoC Analysis of Commercial fresh and degraded LiCoNiAlO2 (Gen-2) ElectrodesProgress/Status : Completed ( in collaboration with Ford Motor Co.)
Subtask 2.2 Local SoC studies of high energy Lithium Rich compositionsProgress/Status: Work in progress
Task-3 In-situ SoC and Structural Studies at Cell Level
Subtask 3.1 Development of in-house fabricated optical Raman Cell in “edge” configuration
Progress/Status: Work in progress
5 Managed by UT-Battellefor the U.S. Department of Energy
Confocal Micro Raman–AFM Setup
Confocal x-y spatial resolution ~ 350 nmConfocal along depth (z) ~ 700 nmExcitation Laser 532 nm
6 Managed by UT-Battellefor the U.S. Department of Energy
500 1000 1500 2000 2500 3000
0
500
1000
1500
2000
2500
3000
3500
Inten
sity (
arbit
rary
unit)
Wave number (cm-1)
Si 1st and 2nd order peak
Video Image50X
532 nm ExcitationGrating 600 lines/mm
50X
Silicon Excess Lithia Composition
7 Managed by UT-Battellefor the U.S. Department of Energy
Task-1 Electrochemical Performance of Li1.2Mn0.525 Ni0.175Co0.1
Two types of composition1. Conventional slurry 85 % active mass- 7.5% each of PVDF and C-black2. Instead of 7.5% C-black- 1.5 % Carbon fiber and 6 % Carbon black
0 20 40 60 80 100 120
120
160
200
240
280
320
360
C/10 rate-25 oCOperating voltage = 2.5V-4.9V
Cycle number
Capa
city
/ mAh
g-1
Charge-Graphite fiber Discharge-Graphite fiber Charge-85-7.5-7.5 Discharge-85-7.5-7.5
0 50 100 150 200 250 300 350
2.5
3.0
3.5
4.0
4.5
5.0
Volta
ge /
V vs
. Li/L
i+
Capacity / mAhg-1
1.5 % graphitic fiber 1.5 % graphitic fiber 85-7.5-7.5 85-7.5-7.5
Materials Supplier Toda Inc.
8 Managed by UT-Battellefor the U.S. Department of Energy
Cycling Efficiency
0 20 40 60 80 100
100
150
200
250
300
350
100
150
200
250
300
350
Capa
city
/ mAh
g-1
Cycle number
Charge-Graphite fiber Discharge-Graphite fiber Faradic efficiency (%) Ef
ficie
ncy
/ %
4.9V
0 50 100 150 200 250 300 350
2.5
3.0
3.5
4.0
4.5
5.0 4.9V4.8V
4.9V
Volta
ge /
V vs
. Li/L
i+
Capacity / mAhg-1
4.9V charge 4.9V discharge 4.8V charge 4.8V discharge
4.8V
9 Managed by UT-Battellefor the U.S. Department of Energy
Rate Performance
0 10 20 30 40 50 60
0
50
100
150
200
250
300
350
Ca
pacit
y / m
Ahg-1
Cycle number
1C
C/20C/10
C/5C/2
1C
5C
5C
2C
2C
C/5
Charge 85-7.5-7.5 Discharge 85-7.5-7.5 Charge-fiber additive Discharge-fiber additive
0 20 40 60 80 100 120 1400
50
100
150
200
250
300
350
2C
C/20C/10
5C
2C
1C
1C
C/2C/5
C/5
Cycle number
Capa
city
/ mAh
g-1
Charge 85-7.5-7.5 Discharge 85-7.5-7.5 Charge-fiber additive Discharge-fiber additive
Materials Supplier Toda Inc.
10 Managed by UT-Battellefor the U.S. Department of Energy
Discharge Capacity : Comparison
0 50 100 150 200 250 300
2.5
3.0
3.5
4.0
4.5
5.0
Capacity / mAhg-1
Volta
ge /
V vs
. Li/L
i+
C/20C/10C/5C/21C5C
0 50 100 150 200 250 300
2.5
3.0
3.5
4.0
4.5
5.0
5C 1C C/2 C/5 C/10
Volta
ge /
V vs
. Li/L
i+
Capacity / mAhg-1
C/20
1.5 % Carbon fiber Conventional
11 Managed by UT-Battellefor the U.S. Department of Energy
60 µm 5 µm 700 nm
Edge
Electrode Secondary particle Primary particle
25 µm
LiNi0.80Co0.15Al0.05O2 (NCA)
LiNi 0.33Co0.33Mn0.33O2 (NCM)
xLi2MnO3 (1-x)LiMO2 ( Excess Lithia compounds)
Task-2 Local State of Charge Concept
300 400 500 600 700 800
Raman shift / cm-1
400
500
600
700
800
900
1000
1100
1200
Cou
nts
Raman Modes of LiMO2 (M = Co, Ni, Cr)
Eg
A1g
Charged NCA cathode (3.77V)
α - NaFeO2 structure
metaloxygen
• A1g – oxygen atoms vibrate in opposite directions parallel to c-axis• Eg – oxygen atoms vibrate alternately in opposite directions parallel to Li and
transition metal planes.• SOC proportional to
c
a
475 cm-1550 cm-1
11 550475 / −− cmcm AA (Kostecki)
Micro-Raman MappingNCA
Carbon
SoC MapMicron
Raman Shift (cm-1)
200 400 600 800 1000 1200 1400 1600 1800
Inte
nsity
0
500
1000
1500
2000
2500
3000
X = -5, Y=1X = 5, Y = 1Fresh Sample (uncycled)
Raman Shift (cm-1)
200 400 600 800 1000 1200 1400 1600 1800
Inte
nsity
500
1000
1500
2000
2500
3000
Exposed Cathode ParticleCarbon Covered Region
NCA
carbon
40 µm
Exposed NCA particle
Carbon coveredregion
Carbon Coverage
X = 6
Raman Shift (cm-1)300 500 8000
1000
2000
3000
40005000
6000 Y = - 6
X = 5
X = 7X = 8X = 9X = 10
1.79
1.080.440.961.21
1.63
X2
X3
Inte
nsity
SoC
SoC
Intensity Map SoC Map : Surface
SoC Map : Edge
00.20.40.60.811.21.41.61.822.22.42.62.8
X (µm)
Y (µm)
Current collector side
Severely Degraded Electrodes
100 % SOC45 oC; 22% SOC swing
17 Managed by UT-Battellefor the U.S. Department of Energy
1200 1300 1400 1500 1600 1700
Raman shift / cm-1
300
400
500
600
700
800
900
1000
1100
1200
1300
Cou
nts
Spatial anode maps of AD1/AG --greater value, more graphite disorder (damage)
1200 1300 1400 1500 1600 1700
Raman shift / cm-1
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
Cou
nts
00.20.40.60.811.21.41.61.822.22.42.62.8
AD1/AG ~ 1.8
AD1/AG ~ 0.1
The Anode Story
reference band cathode cross-section
area x intensity
0 1 2 3 4 5
Cou
nt
0
100
200
300
400
500
600
700
area x intensity
0 1 2 3 4 5
Cou
nt
0
20
40
60
80
100
120
140
160
180
degraded band cathode cross-section
degraded band cathode surface
area x intensity
0 1 2 3 4 5
Cou
nt
0
20
40
60
80
100reference band surface
intensities < 90 filtered out
area x intensity
0 1 2 3 4 5
Cou
nt
0
10
20
30
40
50
average 1.42
0.26
average 1.30
0.24
average 1.51
0.70
average 0.96
0.26
Histogram Analysis : SoC
SoC
19 Managed by UT-Battellefor the U.S. Department of Energy
500 1000 1500 2000
500 1000 1500 2000
Li1.2Mn0.525Ni0.175Co0.1O2
4.9 V ( 100% SoC)
Inte
nsity
(Arb
itrar
y Un
its)
Raman Shift ( cm-1)
Li1.2Mn0.525Ni0.175Co0.1O2
Fresh Electrode
D-Band
G-BandM-O Vibrations
M-O Vibrations
Delithiated
Ratio of Raman peaks of M-O vibrations changes upon lithiation/delithiation
Ex-situ Raman Spectra of Li1.2Mn0.525 Ni0.175Co0.1
M-O Vibrations
20 Managed by UT-Battellefor the U.S. Department of Energy
Micro Raman Imaging of Pristine Li1.2Mn0.525 Ni0.175Co0.1
Video Image
Integrated Carbon Peaks
Integrated M-O Peaks
21 Managed by UT-Battellefor the U.S. Department of Energy
3D Imaging of Lithium in porous Carbon Electrodes : Neutron Radiography
2D Neutron Imaging Reconstructed Radiographs of Li distribution (Li2O2) in Foam Matrices (from coarse to thin matrix)
3D Li distribution (Li2O2) in coarser carbon foam matrix
Nanda, Bilheux et. al. Unpublished 2011
22 Managed by UT-Battellefor the U.S. Department of Energy
Summary and Conclusion
• Good columbic efficiency and capacity of Li1.2Mn0.525 Ni0.175Co0.1
• Stable cycling (> 100 cycles) without high voltage additives and
• Addition of graphitic fibers improves the capacity retention and rate.
• Raman analysis provides spatial information about the electrode SoC
at various cycling conditions.
• Statistical analysis of degraded electrodes.
Work in Progress
• In situ Raman studies of Excess Lithia compositions• High Resolution Electron Microscopy of Excess Lithia compositions atvarious lithiation stages (SoC).
23 Managed by UT-Battellefor the U.S. Department of Energy
Acknowledgments
Mr Tien Duong and David Howell, Energy Storage Team, Office of Vehicle Technologies, EERE, DOE.
Research work supported by High Temperature Materials Laboratory (HTML) at Oak Ridge National Laboratory.
ORNL Team/CollaboratorsDrs; Nancy Dudney, Tom Zawodzinski, Sreekanth Pannala, Claus Daniel, Michael Lance, Wallace D Porter, Hsing Wang, Hassina, Bilheux, Jane Howe, Andrew Payzant, Edgar Lara Cruzio, Karen More, Ray Unocic, C. K. Narula and George Andrews