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1/29 Nicolas Dupré, Dominique Guyomard Institut des Matériaux Jean Rouxel Université de Nantes, France Kouta Suzuki, Masaaki Hirayama, Ryoji Kanno Tokyo Institute of Technology, Japan Electrode/Electrolyte Interface Studies in Lithium Batteries Marine Cuisinier University of Waterloo, Canada

Electrode - Electrolyte Interface Studies in Lithium Batteries

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Compilation of studies conducted at the Institut des Matériaux de Nantes under the supervision of Dr. Dominique Guyomard between 2008 and 2012. Focused on solid-state NMR to characterize interphases between positive electrode and electrolyte.

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Page 1: Electrode - Electrolyte Interface Studies in Lithium Batteries

1/29

Nicolas Dupré, Dominique Guyomard

Institut des Matériaux Jean Rouxel ‐ Université de Nantes, France

Kouta Suzuki, Masaaki Hirayama, Ryoji Kanno

Tokyo Institute of Technology, Japan

Electrode/Electrolyte Interface Studies in Lithium Batteries

Marine Cuisinier

University of Waterloo, Canada

Page 2: Electrode - Electrolyte Interface Studies in Lithium Batteries

2/33

10 100 1000

Po

we

r (W

/ k

g)

Energy (Wh/kg)

10

100

1000

Pb-acid

HEV

EV

PHEV, power tools Li-ion

Energy (Wh/kg, Wh/l)

Power (W/kg, W/l)

Life

Safety

Cost

Toxicity

Reactivity at interfaces

btw. electrodes & electrolyte

Safety

Long term cyclability

Energy Autonomy Power Rate, acceleration

Li-ion & related challenges

Ni-MH

Page 3: Electrode - Electrolyte Interface Studies in Lithium Batteries

3/33

Aging mechanisms of cathode materials

dissolution

re-precipitation of new phases

surface layer formation

electrolyte decomposition

migration of soluble species

gas evolution

Adapted from J. Vetter et al., J. Power Sources 147 (2005) 269

O O

O

O O

OLi

EC DMC

PFF F

F

F

F

LiF

ROCO2Li LixPOyFz

OPF2(RO)nF

Page 4: Electrode - Electrolyte Interface Studies in Lithium Batteries

4/29

Table of contents

CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE

CHARACTERIZATION METHODS 1

Review of interface characterization methods

MAS NMR applied to surface species analysis

Intrinsic interphasial behavior

Surface aging upon storage: characterization and control towards improved electrochemical performance

GENERAL CONCLUSION & PERSPECTIVES

3

4

EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE

Aging upon storage in LiPF6 electrolyte

Aging upon cycling in LiPF6 and LiBOB modified electrolyte

2

Page 5: Electrode - Electrolyte Interface Studies in Lithium Batteries

5/33

Classical interface characterization methods

NMR

From Reuters, Web of Knowledge

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

0

10

20

30

40

50

Pu

blish

ed

ite

ms e

ach

year

Publication year

FTIR

XPS

MAS NMR

A strategy for R&D of Li and Li-ion batteries.

Study of Electrodes Li, Li-C anodes and LixMOy cathodes.

Surface Chemistry

in situ & ex situ FTIR, XPS,

EDAX, EQCM

Morphology

in situ AFM (SEM)

Interfacial properties

EIS, B.E.T. (surface area)

Structural analysis

in situ & ex situ XRD (SEM)

Electroanalytical behavior of Li

insertion compounds

PITT, EIS, SSCV

Solution studies

Electrochemical windows, thermal

stability, redox processes:

CV, in situ FTIR, EQCM, EIS, DTA

Correlation

Optimization of electrolyte

solutions

Performance

Fast tests for cycling efficiency

(GCPL)

Testing in practical cells

(coin cells and AA cells)

Page 6: Electrode - Electrolyte Interface Studies in Lithium Batteries

6/33

Review of interface studies by NMR

< 20 studies in the literature on « passivation layer on LiB materials »

Suitable for: 1H, 7Li, 13C, 19F and 31P in the interphase… or 23Na !

Page 7: Electrode - Electrolyte Interface Studies in Lithium Batteries

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3

0 1..

4 rDµH ijeen

7Li NMR: Li-electron dipolar interaction

Distance between Li and paramagnetic center

Li (nuclear spin)

O B0

Mn4+ t2g

r Through space

(unpaired electron spin)

Coupling between nuclear spin and electronic spin (paramagnetic ions)

q

Page 8: Electrode - Electrolyte Interface Studies in Lithium Batteries

8/33

t0

Free Induction Decay π/2 pulse

T2para

Bulk Surface

acquisition

If r ↓ Hen ↑ then T2 ↓

Using 7Li MAS NMR to selectively DETECT the interphase

DEAD TIME (5-50 s) before acquisition of data

REMOVE Li-bulk SIGNAL

Distance between Li and paramagnetic center

Time

Mn

Li

Li

Longer T2

Short T2

T2 para

x

y B0

Surface species = diamagnetic (Li2CO3, LiF, LixOyPFz etc…)

3

0 1..

4 rDµH ijeen

Page 9: Electrode - Electrolyte Interface Studies in Lithium Batteries

9/33

-2000-10000100020003000

(ppm)

c

b

a

7Li, 500MHz, 14kHz

Li2CO3 powder

LiNi0.5Mn0.5O2 with surface Li2CO3

Surface

Li2CO3

Bulk

Dead time

No dead time

Dipolar

interaction 0 ppm

Diamagnetic

surface species

DIPOLAR INTERACTION

THICKNESS / INTIMACY of the interphase with the bulk

Ménétrier, M. et al. Electrochem. And Solid State Lett., 2004, 7(6), A140.

Dupré, N. et al. J. Mat. Chem., 2008, 18, 4266

Using 7Li MAS NMR to study electrode/interphase interactions

If r ↓ Hen ↑ then T2 ↓

If µe ↑ Hen ↑ then T2 ↓

-40-2002040

2 V4.5 V

7Li / ppmm

Dipolar

interaction

2

1

TFWHM

Page 10: Electrode - Electrolyte Interface Studies in Lithium Batteries

10/33

7Li, 19F and 31P NMR spectra calibration curves

From known amounts of diamagnetic nuclei (LiF, LiPF6)

Works for interphases grown on

≠ electrode materials: LiMn0.5Ni0.5O2 , LiFePO4 , Si

Absolute quantification

of interphasial [Li], [F], [P]

in mmol.g-1 or mmol.m-²

Using MAS NMR to QUANTIFY the interphase

0 25 50 75 100

inte

gra

ted

in

ten

sit

y /

NS

/ R

G (

a.

u.)

diamagnetic Li (µmol)

y = 4.26 10-1x

LiF / LiPF6 calibration

LiFePO4

LiMn1.5

Ni0.5

O4

Si

0

10

20

30

40

50

0 25 50 75 100

0

1

2

3

4

5

y = 2.80 10-2 x

LiPF6 calibration

inte

gra

ted

in

ten

sit

y / N

S / R

G

y = 6.38 10-2 x

LiF calibration

diamagnetic F (µmol)

LiMn1.5

Ni0.5

O4

LiFePO4

Si

19F NMR

7Li NMR

Page 11: Electrode - Electrolyte Interface Studies in Lithium Batteries

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Interpretation of quantitative NMR results

OX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Charge statedia

mag

neti

c L

i o

r F

(m

mo

l.g

-1)

7Li

19F / PF

19F / LiF

7Li, 19F NMR

Total Li (7Li NMR)

Fluorophosphates (19F NMR)

Li in organic ~ Total Li (7Li) – LiF (19F) ?

POF3/PO2F2-/ PO3F2-

O OR

O

Li+

OO

OLi Li

(Li-alkylcarbonates)

(Li2CO3)

PO

R

O

F

F

LiF (19F NMR)

nO O

O OO

O

PO

O

F

FLior

Non lithiated organic species remain invisible to our NMR experiments

Page 12: Electrode - Electrolyte Interface Studies in Lithium Batteries

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Need for COMPLEMENTARY analytical tools

5 0 n m

LiPFLiPF66 electrolyteelectrolyte

decompositiondecomposition

LiMnLiMn0.50.5NiNi0.50.5OO22

interphaseinterphase

formationformation

5 0 n m

LiPFLiPF66 electrolyteelectrolyte

decompositiondecomposition

LiMnLiMn0.50.5NiNi0.50.5OO22

interphaseinterphase

formationformation

Electrode active Electrode active materialmaterialElectrode active Electrode active materialmaterial

DiamagneticDiamagnetic interphasesinterphases

Electrode active Electrode active materialmaterial

NMR XPS

Electrode active Electrode active materialmaterialElectrode active Electrode active materialmaterial

DiamagneticDiamagnetic interphasesinterphases

Electrode active Electrode active materialmaterial

NMR XPS

Electrode active Electrode active materialmaterialElectrode active Electrode active materialmaterial

DiamagneticDiamagnetic interphasesinterphases

Electrode active Electrode active materialmaterial

NMR XPS

Electrode active Electrode active materialmaterialElectrode active Electrode active materialmaterial

DiamagneticDiamagnetic interphasesinterphases

Electrode active Electrode active materialmaterial

NMR XPS

TEM/EELS

Brookhaven Nat. Lab. Z’/Ω

Z’’/Ω

-50

-25

50 100 0 25 75

Rel

Nyquist plot Rinterfacial

In situ EIS

Page 13: Electrode - Electrolyte Interface Studies in Lithium Batteries

13/29

Table of contents

CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE

CHARACTERIZATION METHODS 1

Review of interface characterization methods

MAS NMR applied to surface species analysis

Intrinsic interphasial behavior

Surface aging upon storage: characterization and control towards improved electrochemical performance

GENERAL CONCLUSION & PERSPECTIVES

3

4

EXAMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE

Aging upon storage in LiPF6 electrolyte

Aging upon cycling in LiPF6 and LiBOB modified electrolyte

2

Page 14: Electrode - Electrolyte Interface Studies in Lithium Batteries

14/33

Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon storage (SEM)

1000 500 0 -500 -1000 200 0 -200 -400

no

rmali

zed

/ N

S /

RG

/m

7Li / ppm

30 sec.

3 days

2 weeks

1 hour

5 min.

1 min.

0 ppm

no

rmali

zed

/ N

S /

RG

/m

19F / ppm

LiF

-205 ppm

1 µm

1 µm

(a) (b) (c)

1 µm

19F NMR 7Li NMR

Soaking at RT in LiPF6 1M, EC:DMC (1:1)

Surface “film” observation by SEM

19F: LiF only

Pristine

3 days

1 month

Page 15: Electrode - Electrolyte Interface Studies in Lithium Batteries

15/33

0 10 20 30 40 50 600.0

0.1

0.2

0.3

0.4

300 400 500 600 700

One month

7Li NMR

19F NMR

mm

ol (L

i o

r F

) / g

LM

N

Contact time (min) Contact time (h)

Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon storage (NMR vs XPS)

19F: LiF only

XPS: LiF screening by Li-containing organic species

7Li, 19F NMR

Li in organic = Total Li (7Li)

– LiF (19F)

LiF

LixPFy

LixPOyFz

XPS F1s

1 month

1 hour

5 min. 37%

33% 26%

XPS C1s

CO2

CO

CC/CH

13%

16%

26% 1 month

1 hour

5 min.

CO3

Page 16: Electrode - Electrolyte Interface Studies in Lithium Batteries

16/33

Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon storage (EELS)

LMN½

PF5 + LiF

LiPF6

Salt decomposition Solvents decomposition

Contact time

O OR

O

Li+

O O

O

Ni-L2,3

Mn-L2,3

500 600 700 800 900

8

7

6

5

4

O-K

F-K

Energy Loss (eV)

3

8

5

8 7 6 5 4 30

20

40

60

80

100

% Mn

% F

% Oato

mic

%

spot number

EELS

Interphase growth scenario:

Page 17: Electrode - Electrolyte Interface Studies in Lithium Batteries

17/33

Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon cycling (1)

0 5 10 15 20

100

120

140

160

180

200

220

0 5 10 15 20

25

50

75

100

125

Q charge

Q discharge

Cap

acit

y (m

A.h

.g-1

)

Cycle number

50

60

70

80

90

100

Coulombic efficiency

Co

ulo

mb

ic e

ffic

ien

cy

(%

)

Rct 4.5 V

Rct 2 V

Ch

arg

e t

ran

sfe

r re

sis

tan

ce

(

)

Cycle number

LiPF6 0.9M + LiBOB 0.1MLiPF

6 1M

0 5 10 15 20 25 30

0

5

10

15

20

25

30

Z' / .mg-2

20th

ox

5th

ox

Z"

/

.mg

-2

1st ox

0 5 10 15 20 25 30

0

5

10

15

20

25

30

Z' / .mg-2

20th

ox

5th

ox

Z"

/

.mg

-2

1st ox

0 5 10 15 20

100

120

140

160

180

200

220

Q charge

Q discharge

Cap

acit

y (m

A.h

.g-1

)

Cycle number0 5 10 15 20

100

120

140

160

180

200

220

Cap

acit

y (m

A.h

.g-1

)

Cycle number

Q charge

Q discharge

0 5 10 15 20

100

120

140

160

180

200

220

0 5 10 15 20

25

50

75

100

125

Q charge

Q discharge

Cap

acit

y (m

A.h

.g-1

)

Cycle number

50

60

70

80

90

100

Coulombic efficiency

Co

ulo

mb

ic e

ffic

ien

cy

(%

)

Rct 4.5 V

Rct 2 V

Ch

arg

e t

ran

sfe

r re

sis

tan

ce

(

)

Cycle number

1st charge: parasitic electrochemical process

Impedance ↑ : only Rct ↑

Page 18: Electrode - Electrolyte Interface Studies in Lithium Batteries

18/33

PRISTINEOX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

dia

ma

gn

eti

c L

i/F

(m

mo

l/g

)

Charge state

19

F / LiF

19

F / PF

7Li

0.0

0.1

0.2

0.3

0.4

0.5

0.6

T2(L

i) (

ms

)

PRISTINEOX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

dia

ma

gn

eti

c L

i/F

(m

mo

l/g

)

Charge state

19

F / LiF

19

F / PF

7Li

0.0

0.1

0.2

0.3

0.4

0.5

0.6

T2(L

i) (

ms

)

Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon cycling (2)

O OR

O

Li+

PO

O

F

FLi

0 5 10 15 20

100

120

140

160

180

200

220

0 5 10 15 20

25

50

75

100

125

Q charge

Q discharge

Cap

acit

y (m

A.h

.g-1

)Cycle number

50

60

70

80

90

100

Coulombic efficiency

Co

ulo

mb

ic e

ffic

ien

cy

(%

)

Rct 4.5 V

Rct 2 V

Ch

arg

e t

ran

sfe

r re

sis

tan

ce

(

)

Cycle number

0 5 10 15 20

100

120

140

160

180

200

220

0 5 10 15 20

25

50

75

100

125

Q charge

Q discharge

Cap

acit

y (m

A.h

.g-1

)

Cycle number

50

60

70

80

90

100

Coulombic efficiency

Co

ulo

mb

ic e

ffic

ien

cy

(%

)

Rct 4.5 V

Rct 2 V

Ch

arg

e t

ran

sfe

r re

sis

tan

ce

(

)

Cycle number

Appearance of fluorophosphates

Electrochemical formation of the interphase?

200 0 -200 -400

no

rma

lize

d / N

S / R

G /m

19

F / ppm

OX 1

RED 1

19F NMR

Indirect electrochemical oxidation: oxygen transfer from the oxide surface to the solvent molecules

S.-W. Song et al., JES, 151, A1162 (2004)

Page 19: Electrode - Electrolyte Interface Studies in Lithium Batteries

LMN½ LMN½

Fluorophosphates

Organic species

LiF nO O

O OO

O

PO

R

O

F

F

Li-free organic

19/33

Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon cycling (3)

PRISTINEOX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

dia

ma

gn

eti

c L

i/F

(m

mo

l/g

)

Charge state

19

F / LiF

19

F / PF

7Li

0.0

0.1

0.2

0.3

0.4

0.5

0.6

T2(L

i) (

ms

)

Li-poor interphase:

LiF + non-lithiated species

T2(Li): No evolution of the AM /interphase intimacy

Stable (resistive) LiF-based interphase + growing non-lithiated (PEO type + phosphates)

M. Cuisinier et al. Solid State Nucl. Magn. Reson. 42, 51 (2011)

Page 20: Electrode - Electrolyte Interface Studies in Lithium Batteries

20/33

PRISTINE OX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

dia

mag

neti

c F

(m

mo

l/g

)

dia

mag

neti

c F

(m

mo

l/g

)

dia

mag

neti

c L

i (m

mo

l/g

)

Charge state

19F / LiF

19F / PF

7Li

PRISTINE OX1 RED1 OX5 RED5 OX20 RED20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

dia

mag

neti

c L

i (m

mo

l/g

)

Charge state

19F / LiF

19F / PF

7Li

Cathode protecting agent

Mn-containing insoluble surface layer [*]

LiBOB

Composition of interphase is different: Presence of Li in org. species / fluorophosphates

[*] Chen, Z. et al., Electrochim. Acta 51 (2006) 3322.

« good » interphase ↑ electrochemical performance

0

5

10

15

20

25

30

0 5 10 15 20 25 30

BOB-1oxBOB-5oxBOB-20ox

Z'' /

Oh

m

Z' / Ohm

0

50

100

150

200

0 50 100 150 200

PF6-1oxPF6-5oxPF6-20ox

Z'' /

Oh

m

Z' / Ohm

Example 3: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase upon cycling (effect of LiBOB additive)

No LiBOB

Less resistive interphase

Page 21: Electrode - Electrolyte Interface Studies in Lithium Batteries

21/29

Table of contents

CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE

CHARACTERIZATION METHODS 1

Review of interface characterization methods

MAS NMR applied to surface species analysis

Interphase dynamics upon voltage variations

Interphase modeling using ideal 2D films

Interphase evolution upon extended cycling

GENERAL CONCLUSION & PERSPECTIVES

3

4

EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE

Aging upon storage in LiPF6 electrolyte

Aging upon cycling in LiPF6 and LiBOB modified electrolyte

2

Page 22: Electrode - Electrolyte Interface Studies in Lithium Batteries

22/33

4V 4.5V 2.7V 2V 2.7V 4.5V

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Charge state

dia

mag

neti

c L

i o

r F

(m

mo

l.g

-1)

7Li

19

F/PF

19

F/LiF

Evolution of the LiFePO4 interface with voltage

7Li/19F: clarify XPS stable inorganic interphase

+ fluctuating organic species

FePO4

Oxidized state

LiFePO4

Reduced state

Fluorophosphates

Li-organic species

LiF

4.5 V 4.5 V 2.7 V 2.7 V 2.0 V 4.0 V

Interphase model:

Solid Polymer Layer

F. Croce et aL., J. Power Sources, 43 (1993) 9

Page 23: Electrode - Electrolyte Interface Studies in Lithium Batteries

23/33

Modeling the interphase architecture (1)

-20 0 20 40 60 80 100

20

40

60

80

100

500 550 600 650 700 750 800

% O

% F

% Fe

Ele

me

nta

l p

erc

en

tag

e (

%)

Distance from the surface (nm)

F-KO-K

#12: 14 nm

#11: 19 nm

#10: 18 nm

Energy loss (eV)

#6: AMFe L

2,3

EELS: Any multi-layered model is abusive ! (at least on powder samples)

EELS

Page 24: Electrode - Electrolyte Interface Studies in Lithium Batteries

24/33

Model surface: a- oriented LiFePO4 thin films

Pulsed Laser Deposition: 20-80nm thick LiFePO4 epitaxial film on SrTiO3 (010)

TEM-EELS

Pristine film: structurally homogeneous Possibility to monitor fine surface structure changes upon Li (de)intercalation

a- oriented LiFePO4 thin films

520 525 530 535 540 545 550 555

energy loss (eV)

690 700 710 720 730 740

energy loss (eV)

Fe-L2,3O-K

Ideal 2D surface

= model interphase

Subjected to storage in LiPF6 electrolyte and cycling

Validate the interphase model?

Pulsed Laser Deposition: 20-80nm thick LiFePO4 epitaxial film on SrTiO3 (010)

TEM-EELS

Pristine film: structurally homogeneous Possibility to monitor fine surface structure changes upon Li (de)intercalation

a- oriented LiFePO4 thin films

520 525 530 535 540 545 550 555

energy loss (eV)

690 700 710 720 730 740

energy loss (eV)

Fe-L2,3O-K

1.080.551.06Roughness

t / nm

-20.361.33Thickness

l / nm

5.123.622.11Density

d / g·cm-3

SrTiO3

LiFePO4

Surface

layer

1.080.551.06Roughness

t / nm

-20.361.33Thickness

l / nm

5.123.622.11Density

d / g·cm-3

SrTiO3

LiFePO4

Surface

layer

SrTiO3 substrate

LiFePO4

glue

SrTiO3 substrate

LiFePO4

glue

(a)

(b)

(c)

(d)

Pulsed Laser Deposition: 20-80nm thick LiFePO4 epitaxial film on SrTiO3 (010)

TEM-EELS

Pristine film: structurally homogeneous Possibility to monitor fine surface structure changes upon Li (de)intercalation

a- oriented LiFePO4 thin films

520 525 530 535 540 545 550 555

energy loss (eV)

690 700 710 720 730 740

energy loss (eV)

Fe-L2,3O-K

1.080.551.06Roughness

t / nm

-20.361.33Thickness

l / nm

5.123.622.11Density

d / g·cm-3

SrTiO3

LiFePO4

Surface

layer

1.080.551.06Roughness

t / nm

-20.361.33Thickness

l / nm

5.123.622.11Density

d / g·cm-3

SrTiO3

LiFePO4

Surface

layer

SrTiO3 substrate

LiFePO4

glue

SrTiO3 substrate

LiFePO4

glue

(a)

(b)

(c)

(d)

Hirayama et al., Electrochemistry (Tokyo), 5 (2010) 413

Page 25: Electrode - Electrolyte Interface Studies in Lithium Batteries

25/33

Modeling the interphase architecture (2)

Electron detector

X-ray

3λ. s

in(θ

)

Bulk Surface

θθ

3λ.c

os(θ)

Modeling the interphase architecture

Electron detector

X-ray

3λ. s

in(θ

)

Bulk Surface

XPS

Penetration depth = 3λ.sin(θ) with λ~27Å

θ varied from 0° to 60°I(θ)= Iinf . exp(-d/λ.cosθ)

d, the interphase thickness

3

3.5

4

4.5

5

1 1.2 1.4 1.6 1.8 2

air contact4.5V 1st charge2.5V 1st discharge

1/cos(q)

LN

(P-O

)

1.2 nm1.7 nm0.8 nm

2.5V4.5Vpristine

1.2 nm1.7 nm0.8 nm

2.5V4.5Vpristine

-0.2

0

0.2

0.4

0.6

0.8

1

PO Fe LiF PF CO CO2

4.5V 1st charge2.5V 1st discharge

LN

(su

rfa

ce

/bu

lk)

Interphase depth profile:

bulk

surface

Confirms NMR and EELS results:Inner LiF, covered by fluorophosphates

and a dynamic Solid Polymer Layer (SPL)

Penetration depth = 3λ.cos(θ)

with λ ~ 22 Å

1.0 1.2 1.4 1.6 1.8 2.0

0.4

0.6

0.8

1.0

1.2

1.4

1.6

dried

4.5 V

2.5 V

ln C

(Fe 2

p1/2)

1/cosq -1

d (nm)

Pristine 0.44

1st ox. 4.5 V 1.4

1st red 2.5 V 0.25

Average λ (inelastic mean free path) is inaccurate !

XPS

Voltage dependance of the interphase thickness

% 6

- d

Page 26: Electrode - Electrolyte Interface Studies in Lithium Batteries

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690 688 686 684 682 PO Fe LiF PF CO2 CO ---0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

F 1s

LixPO

yF

z

LiF

C.P

.S

Binding energy (eV)

q = 60°

q = 55°

q = 48°

q = 37°

q = 0°

1st Red

2.5 V

1st Ox

4.5 V

FePO4

LiF

OPF2OMe, OPF2(OCH2CH2)nF

CH2CO2Li, ROCO2Li

LiFePO4

LiF

OPF2OMe, OPF2(OCH2CH2)nF

CH2CO2Li, ROCO2Li

Modeling the interphase architecture (3)

Electron detector

X-ray

3λ. s

in(θ

)

Bulk Surface

θθ

3λ.c

os(θ)

690 688 686 684 682 PO Fe LiF PF CO2 CO-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2F 1s

LixPO

yF

z

LiF

C.P

.S

Binding energy (eV)

q = 60°q = 55°

q = 48°

q = 37°

q = 0°

1st Red - 2.5 V

kA 1st Ox - 4.5 VXPS

Inner interphase: stable / inorganic

Outer interphase : dynamic / polymeric

)0%(

)60%(

C

C

Page 27: Electrode - Electrolyte Interface Studies in Lithium Batteries

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0 20 40 60 80 100

0

20

40

60

80

100

0 20 40 60 80 100

0

20

40

60

80

100

250 Hz

1 ox 4.5 V

5 ox 4.5 V

20 ox 4.5 V

-Z'' /

Z' /

6 kHz

-Z'' /

Z' /

1 red 2V

5 red 2V

20 red 2V

5 kHz

100 Hz

1 20

5 1

20

5

Pristine - 4.5 V Pristine - 2 V

OX1 RED1 OX5 RED5 OX20 RED20

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

0.5

Charge state

dia

mag

neti

c L

i o

r F

(m

mo

l.g

-1)

7Li

19F / PF

19F / LiF

7Li, 19F NMR

0 20 40 60 80 100

80

100

120

140

160

180

Dis

ch

arg

e c

ap

ac

ity (

mA

.h.g

-1)

cycle number

Stable impedance, no resistive film

Accumulation of interphase species

Stable performance vs Li No resistive film

Lots of Li outside LiF, in LixPOyFz (?),

in Li-organic (1H NMR, XPS)

Interphase data upon cycling for bare LFP

O OR

O

Li+P

O

O

F

FLi

Charge transfer

1 ox 5 ox 20 ox 1 red 5 red 20 red

Page 28: Electrode - Electrolyte Interface Studies in Lithium Batteries

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0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

Inte

rph

asia

l 7L

i (m

mo

l.g

-1)

T2(L

i) (

ms)

20 ox 20 red5 red5 ox1 red1 ox

Interphase growth scenario for bare LFP

7Li NMR

T2(Li): decreasing intimacy

Signal integration: accumulation of surface Li

Non blocking interphase,

But no passivation:

Interphase growth by stacking

Stable performance vs Li No resistive film

Li-rich porous interphase

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

Interphasial 7Li (mmol.g

-1)

T2(Li)

(ms)

20 o

x20 re

d5 re

d5 o

x1 re

d1 o

x

FePO4

Oxidized state

LiFePO4

Reduced state

Li+ Li+

Fluorophosphates

Li-organic species

LiF

M. Cuisinier et al. J. Power Sources, 224, 50 (2013)

Page 29: Electrode - Electrolyte Interface Studies in Lithium Batteries

LMN½ LMN½

Fluorophosphates

Organic species

LiF nO O

O OO

O

PO

R

O

F

F

Li-free organic

29/33

STABLE REVERSIBLE “BREATHING”

STABLE PERFORMANCE

STABLE REVERSIBLE “BREATHING”

STABLE PERFORMANCE

Stable performance require a Li-rich organic interphase

How to stop Li consumption in it?

Poor performance of our LMN material might be assigned to a “bad” interphase: no Li mobility, growing Li-free matrix on LiF-rich inner interphase

The case of LiFePO4: summary vs. LiMn1/2Ni1/2O2

LFP FP

M. Cuisinier et al. Solid State Nucl. Magn. Reson. 42, 51 (2011)

M. Cuisinier et al. J. Power Sources, 224, 50 (2013)

Page 30: Electrode - Electrolyte Interface Studies in Lithium Batteries

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Table of contents

CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE

CHARACTERIZATION METHODS 1

Review of interface characterization methods

MAS NMR applied to surface species analysis

Intrinsic interphasial behavior

Surface aging upon storage: characterization and control towards improved electrochemical performance

GENERAL CONCLUSION & PERSPECTIVES

3

4

EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE

Aging upon storage in LiPF6 electrolyte

Aging upon cycling in LiPF6 and LiBOB modified electrolyte

2

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Need for powerful analytical tools Validation of NMR for interphase studies (perspectives)

Use for full cells and negatives: Si or intermetallics Use for the exploration of Na interphasial chemistry

(NaClO4 NaTFSI?) even more critical at the negative

T1/T2(Li) mapping = principle of MRI ! use to localize liquid/confined/solid state Li in the battery

Battery performance is driven by surface chemistry

GENERAL CONCLUSION & PERSPECTIVES

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Interphase evolves upon voltage variations, depending on the AM

No general formation mechanism Complex architecture/composition conducting properties

Good interphase = SEI-like

Li-O-rich to be conducting Dense to passivate the AM surface Thin to limit Li consumption Not straightforward tailor with additives or new electrolytes NMR for the diagnostic evaluation of detrimental phenomena

Cross-talk between the negative and positive interphases

Need for parallel studies on both electrodes

Battery performance is driven by surface chemistry

GENERAL CONCLUSION & PERSPECTIVES

Page 33: Electrode - Electrolyte Interface Studies in Lithium Batteries

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Nicolas Dupré, Dominique Guyomard but also L. Lajaunie, J.-F.

Martin, P. Moreau, Z.-L. Wang (co-workers)

R. Kanno, M. Hirayama, K. Suzuki, S. Taminato (Tokyo Tech collab.)

K. Edström (Uppsala), T. Épicier (INSA Lyon), L. Croguennec,

M. Ménétrier & A. Wattiaux (ICMCB), J.-M. Tarascon (LRCS),

J. Cabana (LBNL) for fruitful discussions and experimental

contributions

MESR, METSA (funding)

[email protected]

[email protected]

Acknowledgments