Aging study of state-of-art cells CYCLING AGING OF...

04/06/2015 Mat4Bat Summer School

MAT4BAT

CYCLING AGING OF LITHIUM-ION

BATTERIES

Aging study of state-of-art cells

1


Outline

• Introduction

• Context & objectives of the Mat4Bat project

• Cycling aging procedures within the

Mat4Bat project

• Cycling aging results on commercial

representative state-of-art cells

2


MAT4BAT

INTRODUCTION


Context

• Use of Evs contribute to reduce emissions of greenhouse gases

and pollutions

• EV with autonomies of 300 km -> storage densities of ~250

Wh/kg

• Battery will stay the most expensive part of the vehicule

have a long life and excellent reliability.

4

250 Wh/kg

lifetime of

>4000 cycles

Mat4Bat


Lifetime of Li-Ion systems within EV application

• Evs will last 5 to 10 years

• Charging and discharging patterns

will affect capacity fade

• EV -> « Dynamic » discharge

conditions

• Li-ion systems lifetime prediction is still an issue for battery

engineers and automotive makers because of multiple aging mechanisms and multiple chemistries (NCA, LFP,

NMC, LTO...)!

• How long will it last? Warranty 5 years, 6 years, 10years?

What is the impact of usage on the battery lifetime?


Aging modes of a battery

• One can distinguish two

battery aging modes :

– CYCLING Mode : Battery is

cycled in charge/ Driving

Mode

– CALENDAR Mode / Parking

Mode : Battery is stored (

I = 0A)

• EV application cycles daily ~ 1 cycle each day

Both calendar and cycling

are important for EV

application

Cycling

Parking


Aging upon discharging/charging « cycling aging »

• Various mechanisms – Mechanical stress (volume changes due

to expansion and contraction of host materials due to lithium intercalation)

– Side reactions : passive layer growth, « lithium metal plating »

• Cycle-life of Li-Ion batteries affected by – Temperature

– C-rate : a lower C-rate will increase cycle life

– Depth of discharge : reduced depth of discharge will increase cycle life

• Role of BMS : – by preventing damaging situations

– But also implement strategies to extend battery lifetime

J. Mater. Chem. A, 2015,3, 2454-2484

Fractures in a

graphite electrode

…


The « cycle-life »

• Cycle life is the number of charge/discharge cycles a battery

can perform before its capacity falls below 80% of its initial

rated capacity.

9

• Cycle life can also be

considered as the total energy

throughput during the life of

the cell.

• The cycle life of Lithium

batteries is typically at least

1,000 cycles.


MAT4BAT

MAT4BAT CONTEXT & OBJECTIVES

10


GENERAL OBJECTIVES

• Use of commercial NMC/Graphite technology as a reference / starting point

• To adress all critical ageing mechanisms associated to this technology

• To propose and implement 3 new generations of Li-Ion cells from liquid, to gel and then to solid-state electrolyte

Project organized in 2 main programs A battery assessment program

- Defining critical charging modalities - Testing tools and methodology for functional performance and

lifetime assessment A battery technology program

- Implementation of new technologies to reach 250Wh/kg at cell level

- Switching from liquid to solid-state electrolyte with Li-Rich oxide and modified graphite active materials for energy density, safety and lifetime

11


Mat4Bat project organization and objectives

12

WP3-4: new battery

technology development

WP1: Battery ageing assessment,

methods & tools

• Ageing tests in calendar and cycling

• Non destructive methods to evaluate

battery lifetime, with additional sensors

• Semi-empirical modeling and battery

lifetime predictions

• Development of new

Li-ion cells

• Density target of 250Wh/kg

• Lifetime target of

>4,000 cycles with a

DOD=80%

WP2: Understanding of ageing

mechanisms, simulations &

modeling

• Ante- and post-mortem analysis of

cells

• Understanding of ageing

mechanisms for improvement of

battery materials

• Multi-physic modeling and battery

design simulation

# 1 Battery assessment program

# 2 Battery technology

program


WP1: Battery ageing assessment

• Kokam 16 Ah cells

commercialy available (2013)

– Nominal specific energy ~

148Wh/kg

– Energy type cells

– Pouch cell design : very good

heat dissipation

– Representative of the state-of-

the-art (SoA) in battery

technologies for Evs

• Possibility to open cells for

ante/post-mortem analyses.

Pouch cell design

#1 : Aging Study of a commercial Li-Ion C/ Carbonate liquid electrolyte /

NMC Cell


WP1: Battery ageing assessment


commercialy available (2013)

– Nominal specific energy ~

148Wh/kg


– Pouch cell design : very good

heat dissipation

– Representative of the state-of-

the-art (SoA) in battery


• Possibility to open cells for

ante/post-mortem analyses.

Pouch cell design

Aging Study of a commercial Li-Ion C/ Carbonate liquid electrolyte /

NMC Cell

0 2 4 6 8 10 12 14 16 182.6

2.8

3

3.2

3.4

3.6

3.8

4

4.2

2C3C

C/2C/5

1C

Discharged Ah

Ce

ll v

olt

ag

e /V

C/25

25°C, fresh cell

Recharge 1C, 4,2V, 25°C


MAT4BAT

CYCLING AGING TEST PROCEDURES

WITHIN THE MAT4BAT PROJECT


Cycling aging conditions

• 3 ambient temperatures* : 5°C, 25°C, 45°C

• 3 Charging rate : 1C, 2C, 3C

• 4 SoC windows investigated (EV application)

16

SOC (%)

100

80

20

0

10

CV step till C/20 at the end of every charge

4 SoC « strategies »

Temperature of

climatic chamber

≠ cell


Cycling aging conditions

17

0 0.5 1 1.5 2 2.5 3 3.5

3.5

3.6

3.7

3.8

3.9

4

4.1

X: 0.9527

Y: 3.42

time / h

Cell

vota

ge / V

X: 1.561

Y: 4.08

25°C

10%-90%,

3C/1C

3C1C

CV step till C/20 at the end of every charge

• No pause between each charging/discharging step

Example of voltage evolution upon cycling

25°C, 10%-90%,

3C/1C


2. Cycling ageing

• Experimental conditions and distribution of cycling tests

18

• 46 cells divided into 21 cycling conditions, 6 experimenters

• * conditions with autopsies (WP2)

Charge C-rate

T [°C]1C ≡ 16A 2C ≡ 32A 3C ≡ 48A Total

45

1C/1C SOC = 0-80% x2 |VITO

1C/1C SOC = 10-90% x2 |CEA

1C/1C SOC = 20-100% x2 |VITO

1C/1C SOC = 0-100% x2 | EIGSI

2C/1C SOC = 0-80% x2 |VITO

2C/2C SOC = 10-90% x2 |CEA

2C/1C SOC = 20-100% x2 |VITO

3C/1C SOC = 0-80% x2 |VITO

3C/3C SOC = 10-90% x2 |CEA

3C/1C SOC = 10-90% x2 |CEA

3C/1C SOC = 20-100% x2 |VITO

3C/1C SOC = 0-100% x4 | EIGSI

26

251C/1C SOC = 10-90% x2 |CEA

1C/1C SOC = 0-100% x2 | KIT

2C/1C SOC = 10-90% x3 |ZSW

2C/1C SOC = 0-100% x2 | KIT

3C/1C SOC = 10-90% x2 |ZSW

3C/1C SOC = 0-100% x3 | KIT14

5 1C/1C SOC = 10-90% x2 |CIDETEC 2C/1C SOC = 10-90% x2 |CIDETEC 3C/1C SOC = 10-90% x2 |CIDETEC 6

Total 14 13 19 46

≡1h

charge ≡30min.

charge

≡20min.

charge

*

* *

*

Charging rate / Discharging rate


WP1/WP2 organisation


Assessing Battery State-of-Health (SoH)

• Periodical electrical tests (“Check-Ups”)

– Performed every 200 cycles @ 25oC

• Number of cycles

• Ah and kWh throughput : cumulated discharged Ah and kWh

• Aging time (days) : time spent at the cycling temperature

• Extended CheckUp / Short Check-Up

Methodology

1 CU performed every 200 cycles


Assessing Battery State-of-Health (SoH)

Electrical techniques Short CU Extended CU

2 capacity tests at

1Cnom=16A define the cell SoH

Discharge DST

Resistance 30s charging

/discharging pulse

95%, 90%, 40%,

20%, 5%

95%, 90%, 80%, 60%,

40%, 20%, 10%, 5%

1 cycle at low current

(C/25) (« OCV ») -

C-rate capability test - C/5, C/2, 1C, 2C, 3C

EIS -

100%, 80%, 60%, 40%,

20%, 0%

21

Overview of techniques during checkups


Extended Check-Up (ECU)

22

SoC values based on the actual cell capacity


MAT4BAT

CYCLING AGING RESULTS


Cell temperature upon cycling

24

0 5 10 153

3.5

4

4.5

Cell

Voltage /V

Time / h0 5 10 15

22

24

26

28

Tem

pera

ture

/°C

25°C, SoC=10%-90%, 3C/1C

0 5 10 153.4

3.6

3.8

4

4.2

Cell

Voltage /V

Time / h0 5 10 15

4

5

6

7

8

Tem

pera

ture

/°C

5°C, SoC=10%-90%, 3C/1C

0 5 10 153.4

3.6

3.8

4

4.2

Cell

Voltage /V

Time / h0 5 10 15

45

46

47

48

49

Tem

pera

ture

/°C

45°C, SoC=10%-90%, 3C/1C

0 2 4 6 8 10 12 14 162.5

3

3.5

4

4.5

Cell

Voltage /V

0 2 4 6 8 10 12 14 1644

46

48

50

52

54

Tem

pera

ture

/°C

Time / h

45°C, SoC=0%-100%, 3C/1C

25oC, 10%-90%, 3C/1C

5oC, 10%-90%, 3C/1C

45oC, 10%-90%, 3C/1C

45oC, 0%-100%, 3C/1C

Cell temperature monitored at the surface

Stop the cycling test when Tcell > 60oC

28

22

8

4

49

45

45

54


0 500 1000 1500 2000 2500 3000 3500 4000 450075

80

85

90

95

100

Number of cycles

Re

lative

ca

pa

city (

CC

+C

V)

/ %

Capacity loss @ 1C, 25°C, Cycling SoC window = 10%-90%

25°C

5°C

45°C

Charging 1C

Charging 2C

Charging 3C

1. Cycling ageing @ ∆SoC=10%-90%

1. Influence of the temperature & C-rate ?

@ ΔSoC=10%-90%

No real influence of C-

rate at 25oC and 45oC

when ΔSoC=10%-90%

Very sharp capacity

loss on the first cycles at

5oC for all C-rates


2. Cycling ageing @ T=25°C

• T = 25oC, effect of

ΔSoC and C-rate ?

Clear influence of ΔSoC

Influence of 3C

charging only

when ΔSoC=0%-

100%

26

0 500 1000 1500 2000 2500 3000 3500 400080

85

90

95

100

105

Cycling number

Re

lati

ve

ca

pa

cit

y (

CC

+C

V)

/ %

Capacity loss @ 1C, 25°C, Cycling Temp. = 25%

10%-90%

0%-100%

T=25°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C



• Influence of the SoC window • T = 45oC, effect of

ΔSoC and C-rate ?

Influence of ΔSoC …

But through the SoCmax !!

Influence of 3C

charging when

ΔSoC=0%-100%

Charging to 100%

(4.2V) @45°C leads to

faster degradation (2x than at SoC=90%)

0 500 1000 1500 2000 2500 3000 3500 400060

65

70

75

80

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

+C

V)

/ %

Capacity loss @ 1C, 25°C, Cycling Temp. 45°C

0%-80%

10%-90%

20%-100%0%-100%

T=45°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C


0 1000 2000 3000 4000 500060

65

70

75

80

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

+C

V)

/ %


10%-90%

20%-100%0%-100%

T=45°CSoC

min%-SoC

max%

0%-80%

Charging 1C

Charging 2C

Charging 3C


• Influence of the SoC window • T = 45oC, effect of

ΔSoC and C-rate ?

Influence of ΔSoC …

But through the SoCmax !!

Influence of 3C

charging when

ΔSoC=0%-100%

Charging to 100%

(4.2V) @45°C leads to

faster degradation (2x than at SoC=90%)

Cycle life x 2 !



Versus Cycling Number … Versus Energy throughput … (Cumulated energy discharged by the batteries)

29

0 20 40 60 80 100 120 140 16060

65

70

75

80

85

90

95

100

105

Energy Throughput / kWh

Rela

tive c

apacity (

CC

+C

V)

/ %


0%-80%

10%-90%

20%-100%0%-100%

T=45°CT=45°CSoC

min%-SoC

max%

Charging 1C

Charging 2C

Charging 3C

0 500 1000 1500 2000 2500 3000 3500 400060

65

70

75

80

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

+C

V)

/ %


0%-80%

10%-90%

20%-100%0%-100%

T=45°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C

Lead to the same results


2. Cycle life of SoA cells

• At 25°C and 45°C, SoCmax = 100% (4.2V) contribute to

accelerated capacity fade in comparison of the 10%-90% &

0%-80% SoC window :

Cycling at 1C from 0 to 100% at 45°C leads to a faster

degradation rate 2x as cycling at 1C or 3C from 10% to 90%

and 0%-80%.

Cycle life ~4000 cycles @ 45°C @ 10%-90% @ 3C !!

• Influence of C-rate is visible only when SoCmax=100% or T=5°C

30


Conclusions

• Lifetime assessment of SoA NMC/ Carbonate liquid

electrolyte / Graphite cells

• Exhibits very good cycle life at 25°C & 45°C

– ~4000 cycles @ 45°C @ 10%-90% @ 3C

• Aging sensitivity to high SoC(High voltage)

• Low temperatures (5°C) are critical even at 1C – Sudden drop of capacity during the first cycles

– Capacity remains steady afterwards


Perspectives

• Lifetime assessment

• Post-mortem analysis will unveil aging mechanisms – Lithium plating at low temperature ?

• Establish a life model decoupling calendar life and

cycle life

– Predictions for practical use for EV application

32


MAT4BAT

QUESTIONS ?


The end

34


Capacity decay: main aging factors

• Comparison with manufacturer datasheet

• Comparison with other chemistries (data available from A123Systems

2,3 Ah)


0 500 1000 1500 2000 2500 3000 3500 4000 450075

80

85

90

95

100

Number of cycles

Rela

tive c

apacity (

CC

+C

V)

/ %


25°C

5°C

45°C

Charging 1C

Charging 2C

Charging 3C

05/06/2015 36


0 50 100 150 200 250 300 35075

80

85

90

95

100

Aging time

Rela

tive c

apacity (

CC

) /

%


25°C

5°C

45°C

Charging 1C

Charging 2C

Charging 3C

05/06/2015 37


0 20 40 60 80 100 120 140 16075

80

85

90

95

100

kWh Throughput

Rela

tive c

apacity (

CC

+C

V)

/ %


25°C

5°C

45°C

Charging 1C

Charging 2C

Charging 3C

05/06/2015 38


0 500 1000 1500 2000 2500 3000 3500 400012

13

14

15

16

17

18

Cycling Number

CC

& C

CC

V C

apacitie

s /

Ah


5°C

45°C

25°C

Charging 1C

Charging 2C

Charging 3C

CCCV capacity

05/06/2015 39


0 500 1000 1500 2000 2500 3000 3500 400080

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

+C

V)

/ %

Capacity loss @ 1C, 25°C, Cycling Temp. = 25%

10%-90%

0%-100%

T=25°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C

05/06/2015 40


0 500 1000 1500 2000 2500 3000 3500 400060

65

70

75

80

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

+C

V)

/ %


0%-80%

10%-90%

20%-100%0%-100%

T=45°CSoC

min%-SoC

max%

Charging 1C

Charging 2C

Charging 3C

05/06/2015 41


0 500 1000 1500 2000 2500 3000 3500 400080

85

90

95

100

105

Number of cycles

Rela

tive c

apacity (

CC

) /

%


25°C

5°C

45°C

Charging 1C

Charging 2C

Charging 3C

05/06/2015 42


0 500 1000 1500 2000 2500 3000 3500 400080

85

90

95

100

105

Cycling number

Rela

tive c

apacity (

CC

) /

%

10%-90%

0%-100%

T=25°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C

05/06/2015 43


0 500 1000 1500 2000 2500 3000 3500 4000 4500 500060

65

70

75

80

85

90

95

100

105

110

Number of cycles

Rela

tive c

apacity (

CC

) /

%

0%-80%

10%-90%

20%-100%

0%-100%

T=45°C

SoCmin

%-SoCmax

%

Charging 1C

Charging 2C

Charging 3C

05/06/2015 44


Mat4Bat Objectives

• 1st focus on NMC/ Carbonate liquid electrolyte / Graphite

• Representative of the state-of-the-art (SoA) in battery


• Technology baseline within the Mat4Bat project

• Incrementat introduction of advanced materials and processes


– Nominal specific energy = 148Wh/kg


• Compatible with EV application

• Possibility to open cells for post-mortem analyses.

• Pouch cell design : very good heat dissipation

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Aging study of state-of-art cells CYCLING AGING OF...

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