Development of Novel
Lithium Salts for
Battery Applications
Outline of the presentation
1.
2.
3.
Introduction – searching for new salts for lithium
batteries
Synthesis and characterization of novel family of
organic covalent lithium salts
Properties of polymer and liquid electrolytes
containing newly developed salts:
•
•
•
•
•
4.
conductivity
lithium transference number
formation of ionic aggregates
electrochemical stability
performance in lithium batteries
Conclusions
Anions:
•
Control dissociation and conductivity
•
Control transport numbers t+ /t-
•
•
are an important part of SEI build-up
at +/- electrodes
Control aluminium corrosion
Classics…
BF4-
ClO4-
Explosive !
Toxic !
PF6-
AsF6-
SbF6-
Tendency to décompose according to equilibrium:
LiBF4  BF3 + <LiF>
LiPF6   PF5 + <LiF>
Fast reaction above 80°C
 Destruction of electrolyte and interfaces
Conceptual approach to anion design

“O” is not a favorable building block:
Strong Li—O interactions  ion pairing, ≠ ClO4-, BOBIf O present, F or CnF2n+1 is required

“N, C” are favorable:
Weak interactions Li—N but easy oxidation
Stability Domains
Fluorinated anions
LiCoPO
LiMO 2
mixed
oxides
4
LiMnPO
4
Non fluorinated anions
LiFePO
4
LiV 3 O 8
Li 4 Ti 5PO
Graphite
Li metal
12
Hückel anions…
Aromaticity 4n + 2 «  » electrons
X = N, C-CN, CRF, S(O)RF
pKA = 10-60
pKA = 10-20
Gain of > 1 eV by resonance
See P. Johansson et al
Physical Chemistry Chemical Physics, volume 6, issue 5, (2004).
LiDCTA
NC
CN
NC
H 2N
NH2
O
O
-2 H 2 O
-
N-
N
N
N
NC
CN
CN
DCTA
N
-
Stable to 3.8 V (La Sapienza, KZ)
inexpensive
N
N
NC
CN
Gives quite fluid ILs
N
N
N
N
-
Most Stable Lithium Imidazole Configurations
1.93 Å
1.88 Å
1.87 Å
1.92 Å
LiTDI
LiPDI
B3LYP/6-311+G(d)
Scheers et al. 2009
Gas Phase Ion Pair Dissociation Energies
Li+ (g) + Anion- (g)
Ion pair (g)
LiTDI
<
LiPDI
<
LiDCTA
<
LiTFSI
<
LiPF6
MP2/6-31G(d)
LiTDI
LiPDI
LiDCTA
LiTFSI
LiPF6
Scheers et al. 2009
LiTDI (2-trifluoromethyl-4,5dicyanoimidazole lithium salt)
O
N
C
NH2
+
C
N
N
C
CF 3
O
C
NH2
O
C
dioxane / T
C
+ Li2CO3 / water
C
N
C
CF 3
C
N
-
N+
Li
- Easy, low-demanding, inexpensive, one-step, high yield
syntheses;
- Salts are pure, stable in air atmosphere, non-hygroscopic,
stable up to 250°C, easy to handle;
CF 3
New salts
N
N N
N
-
N
N N
-
N
Li
N
+
N
Li
CF 3
N
-
LiTPI
Li
LiHDI
Li
+
CF 3
N
N
N
n-C 3 F 7
LiPDI
N
-
+
C 2F5
LiTDI
N
+
Conductivity in PEO
SS / PEO20LiX / SS
0.01
1E-3
1E-4
-1
conductivity /  cm
-1
cooling scan
1E-5
1E-6
DCTA
LiDCTA
PDI
LiPDI
LiTDI
TDI
1E-7
1E-8
2.5
2.6
2.7
2.8
2.9
3.0
3.1
1000/T / K
-1
3.2
3.3
3.4
3.5
LiHDI-PEO Conductivity
-3
1:25 Li/O
1:50 Li/O
-1
log(σ / S·cm )
-4
-5
-6
-7
-8
2,9
3
3,1
3,2
3,3
3,4
3,5
1000·T-1 / K-1
1:25 Ea=76.4 kJ∙mol-1
1:50 Ea=121.8 kJ∙mol-1
T (°C)
127 111
0.01
10
-2
10
-3
10
-4
10
-5
10
-6
10
-7
97
84
72
60
49
39
30
21
13
P(EO)20LiCF3SO3
(Scm )
1E-4
1E-5
PEO
A
PEO2020LiTDI
PEO
LiPDI
PEO 20 B
20
1E-6
2.6
2.8
3.0
1000 / T
-1
N
0.01
N
T / °C
111,5 84 60,1 39,4 21
2,6
2,7
2,8
2,9
3,0
3,1
3,2
3,3
3,4
3,5
-1
1000/T (K )
0.01
PEO20LiCF3SO3+ ZrO2SA
Casting
T / °C
111,5 84 60,1 39,4 21
T/°C
111,5 84 60,1 39,4 21
0.01
-1
+
2,5
PEO20LiBOB/ LiBF4
Hot-Pressing
PEO20LiDCTA
Hot-Pressing
CN
Conducibilità / Scm
Li
Conducibilità / Scm
-1
1E-3
1E-4
1E-5
1E-4
PEO20 LiDCTA
1E-5
PEO20 LiBF4
1E-8
2.4 2.6 2.8 3.0 3.2 3.4 3.6
-1
-1
1000T / K
1E-7
1E-3
1E-4
1E-5
1E-6
1E-6
1E-7
1E-3
-1
N
K
3.2
Conducibilità / Scm
NC
P(EO)20LiDCTA
-1
Conductivity
PEO20LiTDI
PEO20LiPDI
Hot-Pressing
S / cm
1E-3
1E-6
PEO20 LiBOB
PEO20 LiBF4
1E-8
2.4 2.6 2.8 3.0 3.2 3.4 3.6
-1
-1
1000T / K
1E-7
x: 0%
x: 10%
1E-8
2.4 2.6 2.8 3.0 3.2 3.4 3.6
-1
-1
1000T / K
Anodic
stability
Li / PEO LiX / Super P
20
current / mA/cm
2
0.20
DCTA
LiDCTA
PDI
LiPDI
TDI
LiTDI
Anodic breakdown
voltage vs. Li
0.15
0.10
0.05
0.00
3.0
3.5
4.0
4.5
5.0
Potential / V
5.5
6.0
6.5
P(EO)20LiDCTA
3.6V
P(EO)20LiPDI
4.0V
P(EO)20LiTDI
4.0V
Interphase resistance - PEO
Li / PEO20LiX / Li
-60
2h
7h
2d
7d
-100
-40
-20
-80
4.5h
1d
5d
12d
-60
-40
-20
0
0
0
40
80
120
160
200
0
40
80
Zreal / Ohm
2h
7h
2d
7d
-80
-60
LiPDI
4.5h
1d
5d
12d
-40
-20
0
0
120
Zreal / Ohm
-100
Zimm / Ohm
Zimm / Ohm
-80
4.5h
1d
5d
12d
Zimm / Ohm
2h
7h
2d
7d
LiTDI
LiDCTA
-100
40
80
120
Zreal / Ohm
160
200
160
200
Interphase resistance - PEO
Li / PEO20LiX / Li
PDIa
LiPDIa
PDIb
LiPDIb
LiTDIa
TDIa
LiTDIb
TDIb
LiDCTAa
DCTAa
LiDCTAb
DCTAb
240
resistance / Ohm
200
160
120
80
40
0
0
3
6
time / d
9
12
15
Cycling behaviour
% of capacity at C/20
Rate capability (PEO)
% of capacity at C/20
Rate capability (PEO)
LiTDI-PEGDME500 Conductivity
-2,5
2M
1M
0.33M
0.1M
0.033M
0.01M
-3
-1
log(σ / S·cm )
-3,5
-4
-4,5
-5
-5,5
-6
2,9
3
3,1
3,2
3,3
1000·T-1 / K-1
3,4
3,5
3,6
Transference numbers in
PEGDME 500
0.7
LiTDI
LiPDI
0.6
LiHDI
0.5
t+
0.4
0.3
0.2
0.1
0.0
-1
0
1
2
-3
-log(c / mol·dm )
3
4
5
Cation transference number vs.
Ionic conductivity (PEGDME 500)
Salt
Ionic Conductivity
at 1 mol·dm-3 / mS·cm-1
Transference
Number at
1 mol·dm-3
LiTPI
0.05
0.61
LiHDI
0.20
0.21
LiPDI
0.26
0.21
LiTDI
0.28
0.17
LiTDI-PEGDME500
Stability vs. Lithium against time
800
1. sample
2. sample
3. sample
R / Ω·cm
-1
600
400
200
0
0
200
400
t/h
600
800
LiTDI-PC Conductivity
-2,5
1M
0.25M
0.1M
0.033M
0.01M
0.0033M
0.001M
-1
log(σ / S·cm )
-3
-3,5
-4
-4,5
-5
2,9
3
3,1
3,2
3,3
1000·T-1 / K-1
3,4
3,5
3,6
LiHDI-PC Conductivity
-2,5
1M
0.33M
0.1M
0.033M
0.01M
0.0033M
0.001M
0.00033M
-1
log(σ / S·cm )
-3
-3,5
-4
-4,5
-5
-5,5
2,9
3
3,1
3,2
3,3
1000·T-1 / K-1
3,4
3,5
3,6
LiTDI-PC Molar Conductivity
50
20°C
40°C
60°C
30
2
Λ / S·cm ·mol
-1
40
20
10
0
0
0,2
0,4
0,6
c0.5 / mol0.5·dm-1.5
0,8
1
LiHDI-PC Molar Conductivity
12
20°C
40°C
60°C
8
2
Λ / S·cm ·mol
-1
10
6
4
2
0
0
0,2
0,4
0,6
c0.5 / mol0.5·dm-1.5
0,8
1
LiTDI-PC Fuoss-Kraus formalism
association estimation
% of ions / ion pairs / triplets.
100
80
60
ion pairs
triplets
"free" ions
40
20
0
0
1
2
3
-log(c) / mol·dm-3
4
5
LiHDI-PC Fuoss-Kraus formalism
association estimation
% of ions / ion pairs / triplets.
100
80
60
"free" ions
ion pairs
triplets
40
20
0
0
1
2
3
-log(c) / mol·dm-3
4
5
Transference Numbers in PC
0,5
LiTDI
LiPDI
LiHDI
0,4
t+
0,3
0,2
0,1
0,0
0
1
2
3
-3
-log(c / mol·dm )
4
5
Salts-PC Stability vs. Lithium
0,1
LiTDI
LiPDI
LiHDI
0,08
0,06
j / mA·cm
-2
0,04
0,02
0
-0,02
-0,04
-0,06
-0,08
-0,1
0
1
2
3
E / V vs. Li
4
5
LiTDI Conductivity in EC:DMC
-1,5
1M
0.33M
0.1M
0.033M
0.01M
-1
log(σ / S·cm )
-2
-2,5
-3
-3,5
-4
2,9
3
3,1
3,2
3,3
1000·T-1 / K-1
3,4
3,5
3,6
Conductivities (20°C)
Ragone Signature
Anodic limit (Pt, EC-DMC)
Anodic limit (Al, EC-DMC)
Charge profile 4.3 V cut-off, Al collector
Cycling LiMn2O4 4.3 V (EC-DMC)
Swagelok cell , Al plunger
New imidazole-derived salts
• Easy, low-demanding, inexpensive, one-step, high yield syntheses;
• Salts are pure, stable in air atmosphere, non-hygroscopic, stable
up to 250°C, easy to handle;
• 20°C ionic conductivity exceeds:
10-3 S∙cm-1 in PC, 10-4 S∙cm-1 in PEGDME500
10-6 S∙cm-1 in PEO (10-4 S∙cm-1 at 40°C)
6 mS∙cm-1 in EC:DMC
• T+ at ionic conductivity maximum reaches:
0.45 in PC, 0.40 in EC-DMC, 0.25 in PEGDME500 (but overall max
0.62);
• Stable over time against Li;
• Stable up to 4.4 V vs. Li against metallic lithium anode;
• Stable up to 5.0 V vs. Li against aluminum;
• Much smaller association rate than commercially available salts;
Research team working on new salts
Presentation of research team
working on new lithium salts:
Warsaw University of Technology:
- L. Niedzicki and W. Wieczorek – characterization of salts and low molecular weight
polyether electrolytes
- J. Prejzner, P. Szczeciński, M. Bukowska - synthesis of new salts
- Z. Żukowska – spectroscopic studies
Universite de Picardie Jules Verne, Laboratoire de Reactivite et de Chimie des Solides
- S. Grugeon, S. Laruelle - characterization of solid polymeric electrolytes, studies of
electrochemical stability and battery performance
- and M. Armand – development of new salt systems
Faculty of Chemistry, University of Rome, “ La Sapienza
- S. Panero, P. Reale and B. Scrosati, - characterization of solid polymeric electrolytes;
conductivity, transference numbers and electrochemical stability
Department of Applied Physics, Chalmers University of Technology,
- J. Scheers, P. Johansson, P. Jacobsson – modeling and spectroscopic studies
For inquiries about
buying LiTDI
N
(lithium 4,5-dicyano-2(trifluoromethyl)imidazolate)
N
N
please contact:
Leszek Niedzicki
asalm@ch.pw.edu.pl
-
N
CF3
LiTDI
Li
+