Battery Degradation Testing Update

Daiwon Choi, Nimat Shamim,

Alasdair Crawford, Qian Huang,

Vish Viswanathan, Ed Thomsen

Energy Storage Systems Safety and

Reliability Forum

April 20~21, 2021

2

Li-ion Battery

Lead Acid Battery

Flow Battery

ZEBRA Battery

PROJECT OVERVIEW

Grid Storage Launchpad

In Service Planned

From DOE OE Global Energy Storage Database (source NTESS)

3

Practical Data

Scientific Data

Chemistry

Comparison

Degradation Study

Lifecycle

Prediction

BMS Control

State-of-health

Monitoring

Field Use-Case

Data

Materials Single Cell Modules < 100kW Deployed ESS

PROJECT OVERVIEW

4

❑ Develop testing schedules based on standard protocols for industry specific reliability.

❑ Performance comparison of various commercial Li-ion battery chemistries and formats.

❑ Battery performance data processing and analyses.

❑ Support degradation model, state-of-health and prediction.

❑ Battery degradation mechanism analyses.

❑ Correlate single cell to module with BMS and system performance.

PROJECT OBJECTIVES

55

• Degradation at Rest (Intrinsic)

• Chemistry Material compatibility of components (cathode, anode, electrolyte, etc.)

• Time Chemical reaction is time dependent

• State-of-Charge (SOC) Chemical and structural stability of electrodes depends on Li content

• TemperatureChemical reaction is temperature dependent

• Degradation during Operation (Extrinsic)

• Cell FormatDynamic battery performance depends on cell engineering

• Charge/Discharge Rate (C-rate: unit A/h) Rate effects heat, stress and dendrite formation

• Depth-of-Discharge (DOD or SOC)DOD effects electrode volume change and heat

• HeatHeat produced accelerates chemical reaction

DEGRADATION MECHANISMS

6

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

Cu

rre

nt

(A)

V

olt

ag

e (

V)

Te

mp

. (o

C)

BL

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.2525

26

27

28

29

30

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.2525

26

27

28

29

30

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.2525

26

27

28

29

30

FR DOD

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

29

30

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

29

30

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

29

30

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

29

30

FR SOC

0 5 10 15 20 25 30

-5-4-3-2-101

3.00

3.25

3.50

3.75

4.00

4.25

25

26

27

28

29

Time (h)

EV

0 5 10 15 20 25 30

-2

-1

0

1

3.00

3.25

3.50

3.75

4.00

4.2525

26

27

28

29

Cu

rren

t (A

) V

olt

ag

e (

V)

Te

mp

. (o

C)

Time (h)

PS ❑ Variables

• Time : 24h grid cycle (1day)• State-of-Charge (SOC) : 30, 50, 70%• Depth of Discharge (DOD or SOC) : 20, 40, 60%• Power (C-rate): Max. 0.25, 0.5 & 1 • Temperature : 25oC • Number of cells: 3~4• Schedules

BL : Baseline : aging FR : Frequency Regulation PS : Peak Shaving EV : Electric Vehicle

STANDARD BATTERY TESTING

7

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

-2.0-1.5-1.0-0.50.00.51.01.5

2.502.753.003.253.503.754.004.25

24

25

26

27

28

29

Cu

rre

nt

(A)

Vo

lta

ge

(V

)

T

em

p.

(oC

)

Time (h)

Current

Voltage

Temperature

0.12 0.13 0.14 0.15 0.16

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

0.12 0.13 0.14 0.15 0.16

0%

10%

20%

30% 40%

50%

60% 70% 80%

Z'()

- Z

"()

90%

100%

CV DC resistance OCV

❑ Performance Data Analyses• CV (dQ/dV) : voltage profile change and redox

activity• Capacity: degradation of cell• dV/dQ: cathode or anode capacity change• AC impedance : every 10% SOC• DC resistance : every 10% SOC • OCV : every 10% SOC• Temperature : Cell temperature will be used to

calculate the amount of heat energy released after ARC measurement on each cell

STANDARD BATTERY TESTING

8

0

2

4

6

8

10

12

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

0

2

4

6

8

10

12

14

0 2 4 6 8 10

LFP(2.6Ah) NCA(3.2Ah) NMC(3.2Ah) NMC(3.0Ah)

PROJECT RESULTSC

ap

acit

y L

oss (

%)

Time (Months)

Ni 70% Ni 85%

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PROJECT RESULTS

❑ LFP cell show most stable cycling performances.❑ Frequency regulation service most cost effective irrespective of battery

chemistry.❑ Peak shaving degradation is close to EV drive cycle (most deviation).

FR

BL PS

Ni 85% Ni 70%

10

PROJECT RESULTS

Months

❑ CV shows cathode structure change with cycles.❑ dV/dQ show which electrode is degrading more. ❑ Accurate CV and dV/dQ of cathode and anode electrode will

be characterized.

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PROJECT RESULTS

OCV Resistance

12

PROJECT RESULTS

13

PROJECT RESULTS

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

6.E+07

BL

30

BL

50

BL

70

EV

d6

0

FR

40

FR

60

FR

60

LP

FR

80

FR

d4

0

FR

d6

0

PS

d2

0

PS

d4

0

PS

d6

0

Tem

pe

ratu

re

Duty Cycle

Three months average temperature time for each duty cycle in NCA battery

70000000

72000000

74000000

76000000

78000000

80000000

82000000

84000000

86000000

0 20 40 60 80 100 120 140 160 180 200

Area (Temp time)

Average 3month temp 3cells

❑ Cell temperature difference over 25oC (chamber temperature).

❑ Cell temperature variation due to the cell location in the chamber and cooling rate (air flow).

❑ To calculate amount of heat in each cell to understand effect of heat on degradation.

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PROJECT RESULTS

LFP LFP(X) Al(R) NMC(X) NCA NMC1 NMC2

❑ Heat capacity measured using Isothermal Battery Calorimeter.

❑ Total heat will be calculated based on Cp values

❑ Cp of all cells measuredNMC1 (3.0Ah)NMC2 (3.2Ah)Al(R) : Aluminum reference

(X): Cells for Future Additional Test

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❑ Physics and statistics-based state of health model developed.

❑ Continue old test for end-of-life study and characterize degraded cells.

❑ Data analyses on 1 year test results.

❑ Doubling the test capability for additional cell chemistries.

FUTURE WORK

SUMMARY

❑ ~100G of test data accumulated over one year period.

❑ New test setup provides more information with higher accuracy.

❑ In general, higher SOC level and DOD degrades the battery more

but cell chemistry is more important.

❑ LFP cells have better aging, capacity, and energy retention.

❑ Five new chemistries (2 LFP, 2 NMC and 1 LTO) will be added to

the test.

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PNNL is a multi-program national laboratory operated by Battelle for the U.S. Department of Energy (DOE) under Contract DEAC05–76RL01830. This work was supported by the DOE Office of Electricity (OE) under Contract No.57558.

ACKNOWLEDGEMENTS

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Thank You!

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