studies on the local state of charge (soc) and …5c 5c 2c 2c c/5 charge 85-7.5-7.5 discharge...

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


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.


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


Confocal Micro Raman–AFM Setup

Confocal x-y spatial resolution ~ 350 nmConfocal along depth (z) ~ 700 nmExcitation Laser 532 nm


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


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.


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


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.


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


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


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


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


Micro Raman Imaging of Pristine Li1.2Mn0.525 Ni0.175Co0.1

Video Image

Integrated Carbon Peaks

Integrated M-O Peaks


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


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).


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

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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