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.

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

2. Li-ion & related challenges
Energy (Wh/kg, Wh/l)
Power (W/kg, W/l)
Power (W / kg)
HEV
1000
PHEV, power tools
Li-ion
Safety
Cost
EV
Toxicity
Ni-MH
100
Life
Reactivity at interfaces
Pb-acid
btw. electrodes & electrolyte
10
10
100
1000
Safety
Energy (Wh/kg)
Long term cyclability
Energy
Autonomy
Power
Rate, acceleration
2/33

3. Aging mechanisms of cathode
materials
gas evolution
electrolyte
decomposition
DMC
O
O
EC
dissolution
O
surface layer
formation
O
O
re-precipitation of
new phases
migration of
soluble species
F
Li F P F
F
F
F
ROCO2Li
OPF2(RO)nF
O
LixPOyFz
LiF
Adapted from J. Vetter et al., J. Power Sources 147 (2005) 269
3/33

4. Table of contents
1 CHARACTERIZATION METHODS


Review of interface characterization methods
MAS NMR applied to surface species analysis
2 EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE


Aging upon storage in LiPF6 electrolyte
Aging upon cycling in LiPF6 and LiBOB modified electrolyte
3 CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE


Intrinsic interphasial behavior
Surface aging upon storage: characterization and control
towards improved electrochemical performance
4 GENERAL CONCLUSION & PERSPECTIVES
4/29

5. Classical interface characterization methods
A strategy for R&D of Li and Li-ion batteries.
Study of Electrodes Li, Li-C anodes and LixMOy cathodes.
NMR
Surface Chemistry
in situ & ex situ FTIR, XPS,
EDAX, EQCM
Interfacial properties
EIS, B.E.T. (surface area)
Morphology
in situ AFM (SEM)
Structural analysis
in situ & ex situ XRD (SEM)
Correlation
Performance
Fast tests for cycling efficiency
FTIR
(GCPL)
XPS
MAS NMR
50
40
30
Solution studies
Electrochemical windows, thermal
stability, redox processes:
CV, in situ FTIR, EQCM, EIS, DTA
Optimization of electrolyte
solutions
20
10
Published items each year
Electroanalytical behavior of Li
insertion compounds
PITT, EIS, SSCV
Testing in practical cells
(coin cells and AA cells)
19
9
19 4
9
19 5
9
19 6
9
19 7
9
19 8
9
20 9
0
20 0
0
20 1
0
20 2
0
20 3
0
20 4
0
20 5
0
20 6
0
20 7
0
20 8
0
20 9
1
20 0
1
20 1
1
20 2
13
0
Publication year
From Reuters, Web of Knowledge
5/33

6. 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 !
6/33

7. 7Li
NMR: Li-electron dipolar interaction
Coupling between nuclear spin and
electronic spin (paramagnetic ions)
Distance between Li and
paramagnetic center
0
1
H en 
µe .Dij . 3
4
r
Mn4+ t2g (unpaired electron spin)
O
Through space
q
B0
r
Li (nuclear spin)
7/33

8. Using 7Li MAS NMR to selectively DETECT the interphase
T2 para
Distance between Li and
paramagnetic center
B0
0
1
H en 
µe .Dij . 3
4
r
y
If r ↓ Hen ↑
x
Surface species = diamagnetic
(Li2CO3, LiF, LixOyPFz etc…)
π/2 pulse
Bulk
Li
Free Induction Decay
Surface
Time
Longer T2
Mn
then T2 ↓
t0
Li
Short T2
acquisition
T2para
DEAD TIME (5-50 s) before acquisition of data
REMOVE Li-bulk SIGNAL
8/33

9. Using 7Li MAS NMR to study electrode/interphase interactions
7Li,
500MHz, 14kHz
FWHM 
LiNi0.5Mn0.5O2 with surface Li2CO3
No dead time
If r ↓ Hen ↑ then T2 ↓
If µe ↑ Hen ↑ then T2 ↓
a
Bulk
Dipolar
interaction
Dipolar
interaction
0 ppm
b
Diamagnetic
surface species
Dead time
1
T2
2V
4.5 V
Surface
Li2CO3 c
Li2CO3 powder
3000
2000
1000
40
0
 (ppm)
-1000
-2000
20
0
-20
-40
7
 Li / ppmm
Ménétrier, M. et al. Electrochem. And Solid State Lett., 2004, 7(6), A140.
Dupré, N. et al. J. Mat. Chem., 2008, 18, 4266
DIPOLAR INTERACTION
THICKNESS / INTIMACY of the interphase with the bulk9/33

10. integrated intensity / NS / RG
integrated intensity / NS / RG (a. u.)
Using MAS NMR to QUANTIFY the interphase
7Li
NMR
50
40
LiFePO4
20
and 31P NMR spectra
calibration curves
LiMn1.5Ni0.5O4
30
7Li, 19F
Si
-1
y = 4.26 10 x
10
LiF / LiPF6 calibration
0
0
25
50
75
100
diamagnetic Li (µmol)
19F
5
NMR
4
LiMn1.5Ni0.5 O4
3
LiFePO4
Si
Works for interphases grown on
≠ electrode materials:
LiMn0.5Ni0.5O2 , LiFePO4 , Si
-2
y = 6.38 10 x
LiF calibration
2
-2
y = 2.80 10 x
1
From known amounts of
diamagnetic nuclei (LiF, LiPF6)
LiPF 6 calibration
Absolute quantification
of interphasial [Li], [F], [P]
in mmol.g-1 or mmol.m-²
0
0
25
50
75
100
diamagnetic F (µmol)
10/33

11. (Li-alkylcarbonates)
O
-1
diamagnetic Li or F (mmol.g )
Interpretation of quantitative NMR results
7Li, 19F
NMR
Total Li
Li
1.4
7
1.2
Li+ O
(7Li
1.4
O
O Li
(Li2CO3)
O
Li in organic
1.0
~ Total Li (7Li) – LiF (19F) ?
F / PF
19
F / LiF
1.0
R
Li
NMR)
19
O
1.2
0.8
0.8
0.6
Fluorophosphates (19F NMR)
0.4
POF3/PO2F2-/ PO3F2-
0.6
0.4
0.2
0.2
0.0
0.0
OX1
RED1
OX5
RED5 OX20 RED20
O
O
F P
R
O
F
or
F P
O Li
F
LiF (19F NMR)
Charge state
O
O
O
O
n
O
O
Non lithiated organic species remain
invisible to our NMR experiments
11/33

12. Need for COMPLEMENTARY analytical tools
0
n
Diamagnetic interphases
m
LiMn0.5Ni0.5O2
interphase
formation
Electrode active material
NMR
Electrode activ
XPS
Diamagnetic interphases
Electrode active material
LiPF6 electrolyte
decomposition
Electrode active material
Electrode active material
In situ EIS
TEM/EELS
Z’’/Ω
5
NMR
Rinterfacial
-50
Nyquist plot
-25
Rel
0
Brookhaven Nat. Lab.
25
50
Z’/Ω
75
100
12/33

13. Table of contents
1 CHARACTERIZATION METHODS


Review of interface characterization methods
MAS NMR applied to surface species analysis
2 EXAMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE


Aging upon storage in LiPF6 electrolyte
Aging upon cycling in LiPF6 and LiBOB modified electrolyte
3 CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE


Intrinsic interphasial behavior
Surface aging upon storage: characterization and control
towards improved electrochemical performance
4 GENERAL CONCLUSION & PERSPECTIVES
13/29

14. Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon storage (SEM)
7Li
1 month
NMR
19F
0 ppm
NMR
-205 ppm
LiF
3 days
3 days
1 hour
5 min.
1 min.
30 sec.
1 µm
(a)
Pristine
1000
(b)
500
0
7
 Li / ppm


1 µm
normalized / NS / RG /m
1 µm
normalized / NS / RG /m
2 weeks

-500
-1000
(c)
200
0
-200
-400
 19F / ppm
Soaking at RT in LiPF6 1M, EC:DMC (1:1)
Surface “film” observation by SEM
19F: LiF only
14/33

15. mmol (Li or F) / g LMN
Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon storage (NMR vs XPS)
0.4
7Li, 19F
NMR
0.3
7
Li NMR
One month
0.2
19
0.1
0.0
Li in organic
= Total Li (7Li)
– LiF (19F)
0
10
20
30
F NMR
40
50
60
300 400 500 600 700
Contact time (min)
XPS F1s
XPS C1s
LiF
CC/CH
1 hour
LiF only
 XPS: LiF screening
26%
by Li-containing
16% organic species
5 min.
13%
CO
CO3 CO
2
1 month
LixPFy
LixPOyFz
1 month
1 hour
5 min.
Contact time (h)
26%
33%
37%
 19F:
15/33

16. Example 1: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon storage (EELS)
EELS
100
%F
F-K
atomic %
O-K
8
8
7
6
5
4
3
Mn-L
Ni-L
2,3
500
2,3
600
700
800
900
Energy Loss (eV)
80
60
40
20
% Mn
%O
0
8
7
6
5
4
3
spot number
Interphase growth scenario:
LiPF6
O
PF5 + LiF
O
O
O
Li+ O
O
R
LMN½
5
Salt decomposition
Solvents decomposition
Contact time
16/33

17. 200
180
LiPF6 1M Coulombic
160
220
)
220
-1
180
120
160
140
0
5
100
5
15
Cycle number20
10
15
100
st
1 ox
Z" / .mg
-2
25
th
5 ox 90
Q charge
20
Q discharge
15
80
Coulombic efficiency
th
10
60
5
50
0
10
5
10
Cycle number
15
20
15 / .mg-2 20
Z'
25
50
120
20
0
20 ox
70
0
140
Cycle number
30
60
160
100
Coulombic efficiency (%)
-2
0
10
180
30
30
25
20
15
10
5
0
Charge transfer resistance ()
120
70
200
Z" / .mg
Capacity (mA.h.g
200
140
Capacity (mA.h.g
)
Q charge
Q discharge
125
R 4.5 V
ct
st charge:

R 2V
100 1
parasitic
electrochemical process
Impedance ↑ : only Rct ↑
ct
80
75
efficiency LiPF 0.9M + LiBOB 0.1M

6
100
5
90
Q charge
Q discharge
Charge transfer resistance ()
)
100
-1
Capacity (mA.h.g
-1
220
Coulombic efficiency (%)
Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon cycling (1)
0
5
10
Q charge
Q discharge
50
25
0
5
15
20
Cycle number
125
10
15
20
Cycle number
Rct 4.5 V
Rct 2 V
st
100
1 ox
th
5 ox
75
th
20 ox
50
25
5
0
10
15
20
5
Z' / .mg
-2
25
30
10
Cycle number
15
20
17/33

18. RED1
0.3
140
120
0.2
100
10
15
0
0.1
20
5
Cycle number
0.0
0.0
OX5 RED5 OX20 RED1 OX5
PRISTINEOX1 RED20
Charge state
Li+ O
O
R
O
F P
O Li
F
70
60
50
100 RED 1
Q charge
Q discharge
75
Coulombic efficiency
10
R902 V
ct
80
70
50
OX 1
60
25
Cycle number
200
15
0
0
2019
5
50
-200
10
125
100
75
50
25
 F / ppm
Cycle number
-400
0
15
0.0
RED5 OX20 RED20
Charge state
O
80
100
Rct 4.5 V
NMR
Charge transfer resistance ()
0.1
5
0
0.4
Coulombic efficiency
160
125
Coulombic efficiency (%)
100
0.2
)
-1
0.2
90
19F
normalized / NS / RG /m
120
0.5
Q charge
180
Q discharge
Charge transfer resistance ()
0.4
0.3
140
200
100
Coulombic efficiency (%)
0.6
0.4
160
0.6
T2(Li) (ms)
0.8
0.5
Capacity (mA.h.g
1.0
)
-1
1.2
F / LiF
19
200
F / PF
7
180
Li
220
0.6
T2(Li) (ms)
220
19
1.4
Capacity (mA.h.g
LiF
PF
diamagnetic Li/F (mmol/g)
Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon cycling (2)


Appearance of fluorophosphates
Electrochemical formation of the
interphase?
Indirect electrochemical oxidation: oxygen transfer
from the oxide surface to the solvent molecules
S.-W. Song et al., JES, 151, A1162 (2004)
18/33

19. 1.4
1.2
1.0
0.6
19
F / LiF
19
F / PF
7
Li
0.4
0.8
0.3
0.6
0.2
0.4
0.2
0.1
0.0
0.0
PRISTINEOX1
RED1
OX5
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)

0.5
T2(Li) (ms)
diamagnetic Li/F (mmol/g)
Example 2: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon cycling (3)
Li-free organic
RED5 OX20 RED20
Charge state
Organic species
Fluorophosphates
LiF
O
O
O
O
n
O
O
O
LMN½
M. Cuisinier et al. Solid State Nucl. Magn. Reson. 42, 51 (2011)
LMN½
F P
R
O
F
19/33

20. Example 3: aging of the LiNi1/2Mn1/2O2 / LiPF6 interphase
upon cycling (effect of LiBOB additive)
Cathode protecting agent
Mn-containing insoluble
surface layer [*]
No LiBOB
LiBOB
30
19F / LiF
19F / PF
7Li
1.2
1.2
1.0
0.8
0.6
0.6
0.4
0.4
20
15
10
0.2
0.0
PRISTINE OX1
RED1
OX5
RED5
OX20
5
0.0
0.2
BOB-1ox
BOB-5ox
BOB-20ox
25
1.0
0.8
200
1.4
Z'' / (mmol/g)
diamagnetic LiOhm
1.4
Z'' / Ohm
diamagnetic Li (mmol/g)
1.4
0
RED20
Charge state
1.2
150
5
10
15
20
Z' / Ohm
25
30
19F / LiF
19F / PF
7Li
PF6-1ox
PF6-5ox
PF6-20ox
1.2
1.0
1.0
0.8
0.8
100
0.6
0.6
0.4
0.4
50
0.2
0.0
0
1.4
0.2
0
PRISTINE OX1 RED1
0
50
0.0
OX5
100
RED5
OX20 RED20
150
200
Z' / Ohm
Charge state
Composition of interphase is different:
Presence of Li in org. species / fluorophosphates
Less resistive interphase
« good » interphase
[*] Chen, Z. et al., Electrochim. Acta 51 (2006) 3322.
↑ electrochemical performance
20/33

21. Table of contents
1 CHARACTERIZATION METHODS


Review of interface characterization methods
MAS NMR applied to surface species analysis
2 EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE


Aging upon storage in LiPF6 electrolyte
Aging upon cycling in LiPF6 and LiBOB modified electrolyte
3 CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE



Interphase dynamics upon voltage variations
Interphase modeling using ideal 2D films
Interphase evolution upon extended cycling
4 GENERAL CONCLUSION & PERSPECTIVES
21/29

22. -1
diamagnetic Li or F (mmol.g )
Evolution of the LiFePO4 interface with voltage
7
3.0
Li
3.0
19
F/PF
19
2.5
F/LiF
2.5
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0.0
0.0
4.0 V
4V
4.5 V
4.5V
2.0 V
2V
2.7 V
2.7V
2.7 V
2.7V
Charge state
 7Li/19F:
clarify XPS
 stable inorganic interphase
+ fluctuating organic species
FePO4
F. Croce et aL., J. Power Sources, 43 (1993) 9
Oxidized state
4.5 V
4.5V
Interphase model:
Solid Polymer Layer
Li-organic species
Fluorophosphates
LiF
LiFePO4
Reduced state
22/33

23. Modeling the interphase architecture (1)
100
Elemental percentage (%)
EELS
%O
%F
% Fe
80
60
40
20
-20
0
20
40
60
80
100
Distance from the surface (nm)
F-K
O-K
#12: 14 nm
#11: 19 nm
#10: 18 nm
Fe L2,3
500
550
600
650
700
#6: AM
750
800
Energy loss (eV)

EELS: Any multi-layered model is abusive !
(at least on powder samples)
23/33

24. a- oriented LiFePO4 thin films
d / g·cm-3
Model surface: a- oriented LiFePO4 thin films
Thickness
l / nm
20.36
-
Roughness
t / nm
glue
Pulsed Laser
(a)
(b)
Deposition: 20-80nm
thick LiFePO4 4epitaxial
LiFePO
film on SrTiO3 (010)
1.33
1.06
0.55
1.08
690
520 525 530 535 540 545 550 555
700
710
720
730
energy loss (eV)
energy loss (eV)
(d)Pristine film:Surface
LiFePO4
SrTiO3
(c)
structurally homogeneous
layer
O
740
 Possibility to monitor fine surface
Density
2.11
3.62
5.12
structure changes upon Li (de)intercalation
d / g·cm-3
Thickness
a- oriented LiFePO4 thin films
SrTiO substrate
1.33
20.36
Roughness
t / nm
1.06
0.55
l / nm
3
-
TEM-EELS
1.08
O-K
Fe-L2,3
energy loss (e
Pulsed
(d)Pristine film: structurally hom
(b)
Ideal 2D surface
Deposition: 20-80nm
= model interphase
 Possibility to monitor fine
thick LiFePO4 4epitaxial
LiFePO
structure changes upon
film on SrTiO3 (010) Subjected to storage in LiPF6 Li (d
Pulsed Laser
electrolyte and cycling
Pristine film: structurally homogeneous
Deposition: 320-80nm
SrTiO substrate
 Validate to monitor fine surface
 Possibility the interphase model?
thick LiFePO epitaxial
glue
Laser
520 525 530 535 540 54
520 525 530 535 540 545 550 555
energy loss (eV)
4
film on SrTiO3 (010)
690
700
710
720
730
740
energy loss (eV)
structure changes upon Li (de)intercalation
Hirayama et al., Electrochemistry (Tokyo), 5 (2010) 413
24/33

25. Modelingthe interphase architecture
Modeling the interphase architecture (2)
XPS
Electron
detector
Electron
detector
X-ray
X-ray
XPS
)
(θ
in )
. s (θ
n
3λ si
.
λ
3
)
(θ
s
o
.c
3λ
θ
Penetration depth = 3λ.cos(θ)
Penetration depth = 3λ.sin(θ)
with λ ~λ~27Å
with 22 Å
θ
θ varied from 0° to 60°
I(θ)= Iinf . exp(-d/λ.cosθ)
3λ
3λ
Bulk
Bulk
Surface
Surface
Interphase depth profile:
ln C(Fe 2p1/2)
1.6
1.4
1.2
0.8
surface
5
Average λ (inelastic mean free path) is inaccurate !
air contact
4.5V 1st charge
2.5V 1st discharge
0.6
0.4
0.2
1.0
0.8
-0.2
-d
0
0.6
LiF
PF
CO
CO2
Confirms NMR and EELS results:
1.0
1.2
1.4
1.6
1.8
2.0
Inner LiF, covered by fluorophosphates
1/cosq -1
and a dynamic Solid Polymer Layer (SPL)
0.4

d (nm)
4
Pristine
3
1
0.44
1st ox. 4.5 V
3.5
bulk
dried
PO
Fe
4.5 V
2.5 V
4.5V 1st charge
2.5V 1st discharge
4.5
LN(P-O)
LN(surface/bulk)

1
d, the interphase thickness
1.4
1st
1.2
1.4
1.6
1/cos(q)
red 2.5 V
0.25
1.8
% 26
pristine
4.5V
2.5V
0.8 nm
1.7 nm
1.2 nm
Voltage dependance of the interphase thickness
25/33

26. 2
Modeling the interphase architecture (3)
XPS
LiF
F 1s
)
((θ)
θ
sn
i
.
cλos
.3
3λ
X-ray
k
1.0
θ
C.P.S
Electron
detector
1.2
θ
3λ
Bulk
q = 60°
q = 55°
q = 48°
q = 37°
q = 0°
0.8
LixPOyFz
0.6
0.4
0.2
0.0
Surface
-0.2
C %(60)
1.0
C %(0)
1.2
690
686
684
682
P
Binding energy (eV)
1st Ox
4.5 V
0.8
688
0.6
CH2CO2Li, ROCO2Li
0.4
1st Red
2.5 V
0.2
0.0
OPF2OMe, OPF2(OCH2CH2)nF
LiF
LiFePO4
FePO4
-0.2
PO Fe
LiF PF CO2 CO
--
Inner interphase: stable / inorganic
Outer interphase : dynamic / polymeric


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27. 100
180
100
1 ox 4.5 V
5 ox 4.5 V
20 ox 4.5 V
1 red 2V
5 red 2V
20 red 2V
Pristine - 4.5 V
80
Stable impedance,
60
no resistive film
140
120
100
Pristine - 2 V
80
60
-Z'' / 
160
-Z'' / 
Discharge capacity (mA.h.g
-1
)
Interphase data upon cycling for bare LFP
5
40
40
80
0
20
40
60
80
20
1
20
20
20
250 Hz
100
100 Hz
0
cycle number
0
0
20
40
60
80
100
0
Z' / 
-1
diamagnetic Li or F (mmol.g )
7Li, 19F
0.5
NMR
Accumulation of
0.5
interphase species
7
Li
F / PF
19
F / LiF
19
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0.0
1 ox 1 red 5 ox 5 red 20 ox 20 red
OX1
RED1
OX5
RED5
Charge state
1
5
5 kHz
Charge transfer
6 kHz
OX20
RED20
20
40
60
80
100
Z' / 
Stable performance vs Li
No resistive film
Lots of Li outside LiF,
in LixPOyFz (?),
in Li-organic (1H NMR, XPS)
O
F P
O Li
F
O
Li+ O
O
R
27/33

28. 0.0
x 20 red
0.4
0.3
0.3
7
0.2
0.2
0.1
0.1

T2(Li) (ms)
-1
T2(Li) (ms)
0.4
0.0
0.4
0.5
0.3
NMR
0.2
7Li
0.1
Interphasial Li (mmol.g )
Interphase growth scenario for bare LFP
0.0
1 ox 1 red 5 ox 5 red 20 ox 20 red




Stable performance vs Li
No resistive film
Li-rich porous interphase
Interphase growth by
stacking
Li-organic species
Fluorophosphates
LiF
FePO4
M. Cuisinier et al. J. Power Sources, 224, 50 (2013)
T2(Li): decreasing intimacy
Signal integration:
accumulation of surface Li
Non blocking interphase,
But no passivation:
Oxidized state
Li+
Li+
LiFePO4
Reduced state
28/33

29. The case of LiFePO4: summary vs. LiMn1/2Ni1/2O2

Stable performance
require a Li-rich organic
interphase
 How to stop Li
consumption in it?
STABLE REVERSIBLE “BREATHING”
FP
LFP
STABLE PERFORMANCE

Poor performance of our LMN
material might be assigned to a
“bad” interphase: no Li mobility,
growing Li-free matrix on Organic species
LiF-rich inner interphase Fluorophosphates
Li-free organic
O
O
O
O
n
LiF
O
O
O
LMN½
M. Cuisinier et al. J. Power Sources, 224, 50 (2013)
M. Cuisinier et al. Solid State Nucl. Magn. Reson. 42, 51 (2011)
LMN½
F P
R
O
F
29/33

30. Table of contents
1 CHARACTERIZATION METHODS


Review of interface characterization methods
MAS NMR applied to surface species analysis
2 EXEMPLES: LINI0.5MN0.5O2/ELECTROLYTE INTERPHASE


Aging upon storage in LiPF6 electrolyte
Aging upon cycling in LiPF6 and LiBOB modified electrolyte
3 CASE OF THE LIFEPO4/ELECTROLYTE INTERPHASE


Intrinsic interphasial behavior
Surface aging upon storage: characterization and control
towards improved electrochemical performance
4 GENERAL CONCLUSION & PERSPECTIVES
30/29

31. GENERAL CONCLUSION & PERSPECTIVES
Battery performance is driven by surface chemistry
 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
31/33

32. GENERAL CONCLUSION & PERSPECTIVES
Battery performance is driven by surface chemistry
 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
32/33

33. Acknowledgments
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)
marine.cuisinier@gmail.com
nicolas.dupre@cnrs-imn.fr
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