18. GDS Anwendertreffen

26.09.2019, Freiberg

Karsten Richter, Thomas Waldmann, Michaela Memm, Michael Kasper,

Peter Axmann, Margret Wohlfahrt-Mehrens

Zentrum für Sonnenenergie- und Wasserstoff-Forschung

Baden-Württemberg (ZSW)

Aging mechanisms in Lithium ion batteries revealed

by GD-OES depth profiling

- 1 -

Why Lithium ion batteries?

PriceLifetime

Energy

densitySafety

- 2 -

Working principal and aging mechanism

Mechanism related to

Li deposition

SEI

Li

Li

Li

Li

Li

Li

Li Li Li

Anode

CathodeAmbient charging

conditions

Low currents /

room temp.

SEI

Li

LiLi

Li

Li

Li

Li

Li

Li

Challenging

charging conditions

high currents /

low temp.

[1] T. Waldmann, B.-I. Hogg, M. Wohlfahrt-Mehrens, J. Power Sources 2018, 384, 107–124.

- 3 -

Li metal deposition – Spatially resolved

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

depth / µm

Li, O

, P

/ w

t.-%

O

0

20

40

60

80

100

C / w

t.-%

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

O

depth / µm

Li, O

, P

/ w

t.-%

0

20

40

60

80

100

C / w

t.-%

- dominant

dendritic structure

Li metal

deposition

- inhomogeneous

and small dendritic

structures visible

[2] T. Waldmann, J. B. Quinn, K. Richter, M. Kasper, A. Tost, A. Klein, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2017, 164, A3154–A3162.

SEM

CT

- 4 -

Li metal deposition – Effect of resting time

0 2 4 6 80

5

10

15

20

25

30

35

40

P

Li

O

depth / µm

Li, O

, P

/ w

t-%

C

0

20

40

60

80

100

C / w

t.-%

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

depth / µm

Li, O

, P

/ w

t.-%

O

0

20

40

60

80

100

C / w

t.-%

8 h

GD

-OE

SS

EM

- after cell operation:

dominant Li metal

deposition and high

surface concentration of Li

- after resting broad and

flat Li distribution

GD-OES reveals

reintercalation of Li

No dendritic structure

visible

[2] T. Waldmann, J. B. Quinn, K. Richter, M. Kasper, A. Tost, A. Klein, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2017, 164, A3154–A3162.

rest

- 5 -

Aging mechanism – Effect of operating temperature

0 2 4 6 80

5

10

15

20

25

30

35

40

PLi

O

depth / µm

Li, O

, P

/ w

t-%

C

0

20

40

60

80

100

C / w

t.-%

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

depth / µm

Li, O

, P

/ w

t.-%

O

0

20

40

60

80

100

C / w

t.-%

0 2 4 6 80

5

10

15

20

25

30

35

40

P

Li O

C

depth / µm

Li, O

, P

/ w

t-%

0

20

40

60

80

100

C /

wt.-%

Fresh cell: initial SEICycling at 0 °C: Li metal

covers anode Surface

Cycling at 45 °C: Un-

ceasing film formation (e.g.

Li2O, Li2CO3)

[2] T. Waldmann, J. B. Quinn, K. Richter, M. Kasper, A. Tost, A. Klein, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2017, 164, A3154–A3162.

Graphite, LiC6: 372 mAh g-1

Silicon, Li15Si4: 3579 mAh g-1

- 6 -

Increasing demand for energy

lithiation

delit

hia

tion

binder

conductive additive

passiv

atio

n

High volume expansion

- Particle cracking

- Contact loss

- Ongoing film formation and

Li+-Ion consumption

- Formation of passivation

layer and intrinsic

mechanical instability

(mixing, volume change)

- Anisotropic de-/lithiation

[3] M. N. Obrovac, L. Christensen, D. B. Le, J. R. Dahn, J. Electrochem. Soc. 2007, 154, A849. [4] M. N. Obrovac, V. L. Chevrier, Chem. Rev. 2014, 114, 11444–11502.

[5] P. Limthongkul, Y.-I. Jang, N. J. Dudney, Y.-M. Chiang, Acta Mater. 2003, 51, 1103–1113. [6] N. Delpuech, N. Dupre, P. Moreau, J.-S. Bridel, J. Gaubicher, B. Lestriez, D. Guyomard, ChemSusChem 2016, 9, 841–84

- 7 -

Si in LIB anodes – GD-OES approach

0 5 10 15 20 25 30 350

5

10

15

20

25

30

35 GD-OES

EDX

Quantified S

i (w

t.-%

)

Si in reference samples (wt.-%)0 2 4 6 8 10

0

10

20

30

40

50

60

70

80

90

100

(16.5 ± 2.5) wt.-%

(20.5 ± 1.9) wt.-%

(1.1 ± 0.1) wt.-%

(61.0 ± 0.9) wt.-%

(65.9 ± 1.5) wt.-%

Si (w

t.-%

)

depth (µm)

(99.7 ± 1.1) wt.-%

0 100 200 300 4000.0

0.1

0.2

0.3

0.4

Inte

nsity x

10

00

Si (a

.u.)

sputtering time (s)

Initial sputtering

1st interruption

2nd interruption

mean bulk intensity

0 2 4 6 80

5

10

15

20

25

P

Si

C

O

Li, O

, P

, S

i (w

t.-%

)

depth (µm)

Li20

30

40

50

60

70

80

90

100C

(w

t.-%

)

- covering 0-100 wt.-%

Si to analyse graphite

and Si dominant

composite electrodes

- unexpected Si

distribution observed

[7] K. Richter, T. Waldmann, M. Memm, M. Kasper, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2018, 165, A3602–A3604

[8] K. Richter, T. Waldmann, M. Kasper, C. Pfeifer, M. Memm, P. Axmann, M. Wohlfahrt-Mehrens, J. Phys. Chem. C 2019, 123, 18795–18803

- 8 -

Si related aging mechanism – revealed by GD-EOS

0 2 4 6 80

5

10

15

20

25

P

Si

C

O

Li, O

, P

, S

i (w

t.-%

)

depth (µm)

Li20

30

40

50

60

70

80

90

100

C (

wt.

-%)

0 2 4 6 80

5

10

15

20

25

Li, O

, P

, S

i (w

t.-%

)

depth (µm)

Si

P

20

30

40

50

60

70

80

90

100C

(w

t.-%

)

O

C

Li

3x 60s dip washed

with DMC

- Si detectable in DMC with ICP-OES

5 SiO + 6 Li Li2O + Li4SiO4 + 4 Si

5 SiO2 + 4 Li 2 Li2Si2O5 + Si

Side reaction of active material

with electrolyte, consumes Li.

Additional film formation and

dissolution.

[7] K. Richter, T. Waldmann, M. Memm, M. Kasper, M. Wohlfahrt-Mehrens, J. Electrochem. Soc. 2018, 165, A3602–A3604

[8] K. Richter, T. Waldmann, M. Kasper, C. Pfeifer, M. Memm, P. Axmann, M. Wohlfahrt-Mehrens, J. Phys. Chem. C 2019, 123, 18795–18803

- 9 -

Si related aging mechanism – revealed by GD-EOS

0.0 0.5 1.0 1.5 2.00

5

10

15

20

25

30

35

40

Si / w

t.-%

depth / µm

Formation

50 Cy C/3 RT

50 Cy C/3 45 °C

40 Cy C/3 0 °C

0 2 4 6 8 100

5

10

15

20

25

30

35

40

Si / w

t.-%

depth / µm

Formation

50 Cy C/3 RT

50 Cy C/3 45 °C

40 Cy C/3 0 °C

0 2 4 6 8 100

5

10

15

20

25

30

35

Si / w

t.-%

depth / µm

Formation

50 Cy C/3 RT

50 Cy C/3 RT MdCh

25 Cy MdCh 25 Cy C/3 RT

0.0 0.5 1.0 1.5 2.00

5

10

15

20

25

30

35S

i / w

t.-%

depth / µm

Formation

50 Cy C/3 RT

50 Cy C/3 RT MdCh

25 Cy MdCh 25 Cy C/3 RT

- Si distribution depends on physical

and electrochemical operation

conditions

- 45 °C enhances film formation,

containing Si-rich species

- 0 °C shifts the Si distribution to

deeper levels of the electrode

- lower cut off potential increases Si

species on surface

Enhanced side reactions during

discharge

- 10 -

Conclusions

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

depth / µm

Li, O

, P

/ w

t.-%

O

0

20

40

60

80

100

C /

wt.-%

- GDOES provides spatially resolved elemental

distribution

Covering the plating behaviour over the jelly

roll

- GDOES provides information about the aging

mechanism regarding cell operation conditions

Differentiation between, e.g. Li metal

deposition or electrolyte decomposition

- GDOES can be calibrated to novel battery

materials revealing material specific aging

mechanism

Film formation and dissolution on Si/C

composite materials

0 2 4 6 80

5

10

15

20

25

30

35

40

PLi

O

depth / µm

Li, O

, P

/ w

t-%

C

0

20

40

60

80

100

C / w

t.-%

0 2 4 6 80

5

10

15

20

25

30

35

40

C

P

Li

depth / µm

Li, O

, P

/ w

t.-%

O

0

20

40

60

80

100

C /

wt.-%

0 5 10 15 20 25 30 350

5

10

15

20

25

30

35 GD-OES

EDX

Quantified S

i (w

t.-%

)

Si in reference samples (wt.-%)

0 2 4 6 80

5

10

15

20

25

P

Si

C

O

Li, O

, P

, S

i (w

t.-%

)

depth (µm)

Li20

30

40

50

60

70

80

90

100

C (

wt.

-%)

0 2 4 6 80

5

10

15

20

25

Li, O

, P

, S

i (w

t.-%

)

depth (µm)

Si

P

20

30

40

50

60

70

80

90

100

C (

wt.-%

)

O

C

Li

electrode

washing

- 11 -

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Forschung Baden-Württemberg (ZSW)

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Funding:

MAT4BAT – EU (n° 608931)

LIB.DE – BMWi (n° 03ET6081A)

ZSW:

Niloofar Ghanbari (now Bosch)

Thomas Waldmann

Michaela Memm

Michael Kasper

Peter Axmann

Margret Wohlfahrt-Mehrens

Spectruma:

Rüdiger Meihsner

Tatjana Leibßle

Otto Paljok

Tahir Serbet

Michael Analytis