ionic liquid electrolyte development
TRANSCRIPT
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Page 1
Ionic Liquid-based Electrolytes for Next Generation Batteries
Stefano PasseriniUniversity of Muenster, Institute of Physical Chemistry, Corrensstr. 28/30 Muenster
Germany
Beyond Lithium Ion, June 5, 2012
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Muenster
ElectrochemicalEnergy
Technology
Research Groups:
Prof. Martin Winter
Prof. Stefano Passerini
Young Researcher Groups:
Dr. Alexandra Lex-Balducci (2009 -)
Dr. Andrea Balducci (2009 -)
Dr. Jie Li (2012 -)
50 Ph.D. Students
30 Scientists with Ph.D.
10 Bachelor Students
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Ionic Conductivity in IL-based Materials for
Energy Storage
Liquid electrolytes
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Ionic Conductivity in IL-based Materials for
Energy StoragePolymer electrolytes
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Li Ion Batteries Initiated a Technical Revolution....
and might be ready for more
20051990 by SonyMarket Introduction
medium
0.7Bio (2008) 7Bio (2008)Market Size
LEV, Power ToolsConsumer
Applications
ModerateMinimalChances for
Newcomers
Realization hasto be proven
Very large
Stationary Elec.
Storage
Depends on
starting position
100 10.0000.1 10.001 0.1Typ. Battery-Size
(kWh)
2012/15(mostly HEV)
large
25Bio (2020)
Automotive
HEV & EV
(Very) Good
1 100
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Conductivity
Vapor pressure
Environment - friendly
Film forming ability (SEI)
Electrochemical stability window
Temperature range of use
Electrolyte System
State of the art:
Organic solvent-based electrolytes
LiPF6, EC, DEC, additives
Key-role of Electrolyte in Li-Ion Batteries
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Separator
SEI
Neg.
CurrentCollector(Cu) P
os.CurrentCollector(Al)
Anode CathodeElectrolyte
Li-Ion cells: Role of the SEI film
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However ..
Safety of present Li-ion cells is still an open issue
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LixC6 + LiyMOz C6 + Li(y+x)MOz
Cu Graphite SEI org. Electro lyte Film Cathode Al
Li+
X-
"Full" "Empty"
Or
" Empty"
LixC6 Li+ Li+ LiyMOz
Towards Safer Batteries:
What do we learn from LIBs?
Key Step Forward: Replacement of volatile, flammable and
electrochemically unstable electrolyte components
Room temperature molten salts (Ionic Liquids)
PYR14FSI
Ionic Liquid-based
Electrolyte
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butyl conformations found in
various crystal structures
well-know flexibility of the TFSI- anion
between 2 low-energy conformations
Ion Conformational Changes
Weak interactions due to large cation and anion
delocalization and low tendency to crystallize due toflexibility (anion) and dissymmetry (cation)
Ionic Liquids Low Temperature Melting Salts
Salts, or mixtures of salts (composed solely of ions), which are liquidat low temperatures (< 100C) often below RT
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0 sec
ORGANIC ELECTROLYTE IONIC LIQUID ELECTROLYTE
0 sec
2 sec
3 sec
Flammability: Organic electrolyte vs. Ionic
Liquids
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Ionic Liquids (IL, RTIL, RTMS, etc.)
Properties
Wide electrochemical window
Wide liquid range
Very low volatility at ambient
pressure
Good thermal stability
High ionicity
Co-salts for
solid-state
polymer electrolytes
Solvents for
liquid electrolytes
Thousands of possible ILs available
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PYR13TFSI ionicliquidImpurities: < 100 ppm
Water: < 10 ppm
Clear, uncolored
G.B Appetecchi et al., JES 153(9) (2006) A1685.
Synthesis of Ionic Liquids
N
I-
+N
I+ethyl acetate
filtration
N
TFSI-
+
LiTFSI aq.
phase separ.
purification
AC & Al2O3
Li = lithium
PYR1A = N-alkyl-N-methylpyrrolidinium
TFSI = bis(trifluoromethanesulfonyl)imide, (CF3SO2)2N-
FSI = bis(fluorosulfonyl)imide, (FSO2)2N-
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Boosting PerformanceCombining Ionic Liquids
PYR13FSI (m.p. -10C) - PYR14TFSI (m.p. -5C)
Mixtures have much lower
melting temperatures than
constituent Ionic Liquids
due to additional ion
mismatching
Castiglione et al. JPC B113, 10750 (2009), Zhou et al. JPC C 114, 6201 (2010), Kunze et al. JPC C 114, 12364 (2010)
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Are ionic liquids capable of dissolving Li salts?
PYR13TFSI - LiTFSI
Yes, but only at low Li concentration because new crystalline phases are
formed for high Li contentHendersonetal.Chem.Mater.16,2881(2004)
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Aggregation of Pyr1NTFSI ILs (NMR, Raman)
N+
CH3
CH3
N+
CH3CH3 Pyr13
+
Pyr18+
Pyr14+
Pyr15+
Pyr16+
Pyr17
+
N-
S S
CF3 CF3
OO
OO
TFSI
polar&
chargedregion
nonpolar
region
chargecompensation
Pyr
TFSI
TFSI
TFSI
TFSI
variation of sidechain length
Pyr1[2O1]+
TFSI
variation of sidechain type
Pyr1[2O2]+
nonpolarsidechains polarsidechains
N-
S S
CF3 CF3
OO
OO
N+
CH3
CH3
N+
CH3
CH3
N-
S S
CF3 CF3
OO
OO
TFSI
Li+
Effect of Li+
cation
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Local Motion in Ionic Liquids:
NMR characterization (Two Step Model)
s >> 1:
R1 only influenced by fast bond rotationsin the molecule that take place during the
time f not influenced by aggregation of
molecules
R2 is largely influenced by the slowreorientations and experiences the
molecular aggregation
2 22 2 2 222
11 1
fs
s f
J S S
23cos 12
S
22 2
2 1
9
20s
R R R S
Wennerstrm,H.,etal.J.Am.Chem.Soc.101,68606864(1979)
spectraldensity:
fcharacterizes the fast internalmotions (bond rotations)
s describes rotational tumbling
of the molecule
spinlattice and spinspin relaxation of a
surfactant are sensitive to fast local
motions and slow motions, respectively
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0
2
4
6
8
10
12
+LiTFSI+LiTFSI+LiTFSI
Pyr14
TFSI Pyr15
TFSI Pyr16
TFSI
R(
2H
)/s-1
Pyr(x)TFSI
R1
R2
R
Pyr13
TFSI
+LiTFSI
0.00
0.05
0.10
R/
NMR measurements: T1 and T2 vs x (in Pyr1xTFSI)
Typical behavior of micelles indicating the formation of aggregates
Aggregation in Pyr1xTFSI
R1 independent on chain length
fast local motions not influenced
R2 dependent on chain length
slow local motions influenced
two different linear dependences different aggregation
mechanisms
In presence of Li+ R differs from 0
already for propyl chain
Li forces cation aggregation
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Pyr15TFSI
Aggregation type?
Pyr14TFSI
increaseofthe
numberof
cations
inanaggregate
increaseofthe
numberof
cations
inanaggregate
Pyr13TFSI Pyr16TFSIPyr18TFSI
increaseofaggregatesize
dueto
increasing
chainlength
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Raman measurements
The aggregation isconfirmed by the shift of
characteristic Raman peaks
Aggregation in Pyr1xTFSI
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Cation aggregation: Li+ --- TFSI- ion-pairing
nin Li TFSI n
increase of anions,
which surround the Li+
@ 742 cm-1 expansion and
contraction of the whole TFSI-anion
@ 748 cm-1 damped TFSI-anion
expansion and contraction due to
Li+ clustering
increase of mode @ 748 cm-1 with
increasing side chain length
more anions are clustering the Li-
cation when more Pyr-cations
cluster with themselves
M. Kunze, et al., Adv. En. Mat. (2011) 1,1
LiTFSI LiTFSI
Li---TFSI
Li---TFSI
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PYR+1x aggregate formation in presence of Li+
increase of the
number of cationsinanaggregate
increaseofthe
numberof
cations
inanaggregate
increaseofaggregatesize
dueto
increasing
chainlength
Pyr13TFSI Pyr14TFSI Pyr15TFSI Pyr16TFSIPyr18TFSI
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Paillard et al., JES 156, A891(2009) Zhou et al. JPC C 114, 6201 (2010)
Sub-ambient temperature
melting electrolytes
The electrolytic mixture
0.85 PY14FSI - 0.15 LiFSI
melts below -40C
The electrolytic mixtures with
x> 0.15 show only glasstransition below -60C
x LiFSI (1-x) PYR14FSI
Tailored electrolyte: Li salt in PYR14FSI
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High ionic conductivity at
sub-ambient temperaturesWide Electrochemical Stability
Window (ESW)
LiFSI PYR14FSI mixtures for electrolytes
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ANODE: Li4Ti5O12 (LTO)
CATHODE: LiFePO4 (LFP)
BINDER: CMC
ELECTROLYTE: 0.1LiTFSI 0.9 PYR14FSI
ILLIBATT Prototype
Active material loading: 0.6 0.8 mAh/cm2
Total Capacity: 0.7 0.8 Ah
Stack (12 layers) of bipolar electrodes
Ionic Liquid-based Lithium-ion Batteries
ELECTROLYTEELECTRODES PROTOTYPESTACK OF ELECTRODES
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Li-Ion cells (LFP-LTO) with Ionic Liquid-based Electrolytes
Very promising
cycling performance
LTO/ 0.9PYR14FSI 0.1LiTFSI / LFP
Pouch Cell, glass fiber, 20CCMC binder aqueous slurries Al collectors
Appetecchi G. B, et al.J. POWER SOURCES 196, 6703-6709, 2011
Vacuum test
1- Two identical vacuum sealed cells differing only for the electrolyte
2- The cells are placed under the same vacuum level
ORGANIC ELECTROLYTE IONIC LIQUID
Operation under
vacuum
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Aluminum in PYR14TFSI - LiTFSI electrolytes
0 40 80 120
0,00
0,05
0,10
0,15
0,20
0,25
0,30
j/mAcm
-2
t/min
PC-LiTFSI
80wt% PYR14
TFSI + 20wt% PC + LiTFSI
PYR14
TFSI -LiTFSI
0 200 400 600
0,00
0,01
0,02
0,03
0,04
0,05
j/mAcm
-2
t/min
PC-LiTFSI
80wt% PYR14
TFSI + 20wt% PC + LiTFSI
PYR14
TFSI -LiTFSI
(80%PYR14TFSI-20%PC)-LiTFSI PYR14TFSI-LiTFSIPC-LiTFSI
Chronopotentiometry at 4.6 V vs. Li/Li
Al corrosion suppressed with TFSI-based electrolytes1 R.-S. Khnel,et al, J. Power Sources, in press (2012)
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HighVoltageElectrodes:ILvs [email protected]
Very high capacity after long-term cycling
High coulombic efficiency (pract. 100%)
Li / Electrolyte / Li[Li0.2Mn0.56Ni0.16Co0.08]O2Pouch Cell @ 40C and C/2
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High-Energy (Next-Generation) Battery Technologies
>500 Wh/kg RevolutionaryTechnology-
Change
Pb-acid 3000 kgNi-MH 1200 kg
Super- Battery < 200kg
Li-ion Batteries
Year
Present 2017
170 Wh/kg*
250 Wh/kg*Estimated
limit of
Lithium-Ion
Technology
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"4V"
Li-Ion
Oxide
Cathodes
Li-Element batteries
1
2
3
4
5
6
250 500 750 1000 1250 1500 1750 40003750
Potentia
lvs.
Li/Li+
0
0
Capacity / Ah kg -1
Li
metal
O2 (Li2O)
F2
S
O2 (Li2O2)
Lithium-Element
Battery Cathodes
Theor. Energy: 3000-5000 Wh/kg
4 Li + O2 2 Li2O E = 2.91
V
2 Li + O2 Li2O2 E = 3.10V
Combustion Energy of Gasoline
Theor. Energy: 13500 Wh/kg
Practical Energy: 2700 - 3000 Wh/kg
C8H18 + 25/2 O2 8 CO2 + 9 H2O
CO2
CO2 + H2O
Gasoline
Li2O
Li2O2
Li
13500
3750
3000
11700
5200
3500
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Anode
(Li/LixSi)
Li+ ion
conducting
electrolyte
-
Li+Li
Li2O/Li2O2
AirLi+
V I
Oxygen
harvesting
Lithium-electrolyte
interface
KEY ISSUES OPEN
Oxygen Redox
reaction
Target:
500Wh/Kg & 200W/kg at the
battery pack
Li-Air batteries: Splitt ing the Issues
O2
Participant organisation name Country
Westfaelische Wilhelms-Universitaet Muenster (WWU) DE
Tel Aviv University (TAU) IL
Consejo Superior de Investigaciones Cientificas (CSIC) ES
Kiev National University of Technology and Design (KNUTD) UKR
University of Bologna (UNIBO) IT
University of Southampton (SOTON) UK
SAES Getters S.p.A. (SAES) ITChemetall DE
AVL List GmbH (AVL) AT
Volkswagen (VW) DE
European Research Services GmbH (ERS) DE
EU Project LABOHRFP7-2010-GC-ELECTROCHEMICAL STORAGE265971
Conventional electrolytes based on carbonates and ethers have beenruled out because of insufficient stability for ORR
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FFO
O
O
O
SSN
-
F
F
FF
F
FO
O
O
OSS
N-
FF
F
F
F
F
F FF
FF
F
O
O
O
OSS
N-
F
F
FF
F
F
F
FF
F
O
O
O
O
SSN
-
CH3CH3
N+
CH3OCH3
N+
4 anions vs. 2 cations
FSI BETI
TFSI IM14
PYR14+
PYR12O1+
Investigated ILs for Li-Air cells
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0 50 100 150 200
-20
-15
-10
-5
05
10
15
20
Stripping on Nio
Plating on NioC
ellOvervoltage(mV)
Cycle Number
0.25mAcm-2
at 20oC
-20
-15
-10
-5
0
5
10
15
20
190th
100th
150th
50th
1st
0.25mAcm-2
at 20oCC
ellOvervoltage(mV)
Cycle
0 5 10 15 20 250
5
10
15
20
25
-jZ''(cm
Z'(cm2)
After 180 cycles
Li plating/stripping from IL-based electrolytes
Li / 0.1LiTFSI-0.9PYR14FSI/Ni (20C, 0.25 mAcm-2, sealed cell)
Very promising cycle performance
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Li plating/stripping from IL-based electrolytes
Li / 0.1LiTFSI-0.9PYR14FSI/Ni (20C, various current rates,sealedcell)
Limited rate performance
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Li plating/stripping from IL-based electrolytes
Li / 0.1LiTFSI-0.9PYR12O1TFSI/Li (60C sealed cell)
Open challenge: 1 mAcm-2
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Effect of (dry) air on Lithium plating/stripping
Li+
Li / IL / Ni
Li+
Li / IL / Ni
e- e- 10h plating at 0.1 mA cm-2
Cycles of 1h stripping / 1h plating
0.1 mA cm-2, Vcut-off= 0.5V
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Pyr12O1 FSI: LiTFSI 9:1 (open dry air)
Good cycling performance even in presence of air
PYR14 is more stable than PYR12O1 in dry air
Pyr12O1FSI: LiTFSI 9:1
20C
37 cyclesEff = 86.4%
Pyr14FSI: LiTFSI 9:1
20C
59 cycles
91.5%
Lithium Metal Polymer Batteries (LMPBs)
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Lithium Metal Polymer Batteries (LMPBs)
10-2 Scm-1
10-3 Scm-1
10-6 Scm-1
10-7 Scm-1
Organic Liquid Electrolytes
Room T
conductivity
10-4 Scm-1
Polymer + LiX
10-5 Scm-1- no liquid compounds
- high safety
- high energy density
- very good processabil ity
but . poor RT conductivity
Incorporation of ILs has resulted in high ionic conductivity SPEs
Polymer + LiTFSI
large
anion X-
IL
Polymer + LiX+ Ionic Liquid*
J.-H. Shin, et al.. Electrochem. Comm. 2003, 5, 1016. Ionic liquids to the rescue? Overcoming the ionic conductivity limitations of polymer electrolytes.
PEO LiX IL electrolytes: SPEs
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PEO-LiX-IL electrolytes: SPEs
Poly(ethylene oxide)
PEO, n ~ 91.000Molecular weight ~ 4 Mio.
Composition is given as:Molar ratio of P(EO) : Li salt : IL
[ 20 : 2 : 4 ]
Li TFSI PYR14TFSI Benzophenone
Good adhesiveness
Excellent mechanical properties
PEO-LiX-IL electrolytes: conductivity and
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PEO LiX IL electrolytes: conductivity and
stability
Laminated, vacuum
sealed Li/SPE/Ni cells
wide ESW
High ionic conductivity
Excellent mechanical, chemical
and electrochemical stabilities
high chemical stability
Laminated, vacuum
sealed Li/SPE/Li
cells
PEO : LiTFSI : PYR14TFSI = 20:2:4 (mol)
Lithium metal electrode operation appears
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Lithium and
electro lyte layers Bipolar cathode Cell stack
Vacuum Sealed Cell
Lithium metal electrode operation appears
feasible in IL-based electrolyte
Li/ IL-based electrolyte/ LFP1Ah prototype
B tt t t PEO IL LiX l t l t (RT t t )
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Li / P(EO)10LiTFSI-PYR14TFSI / LiFePO4
Very large capacity increase due to IL incorporation > 100 mAhg-1 at 20C
Theoretical capacity (170 mAhg-1) at 30C
Battery tests: PEO-IL-LiX electrolyte (RT tests)
PEO-LiX-IL electrolytes
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PEO LiX IL electrolytes
How do ILs enhance Li+ conduction?
TFSI-
Li+
PEO host
Li+
Li+
TFSI-
PYR+
PYR+
TFSI-
PEO-LiX electrolyte: Li+ is strongly
coordinated by PEO host
PEO-LiX-IL electrolyte:solid ternary system composed by a polymerhost (PEO) and two salts (LiTFSI and
PYR14TFSI)
very weak interactions between PYR14+ andTFSI- [1]
no interaction between PYR14+ and PEO host(Raman & NMR) [2,3]
strong interactions between Li+ and TFSI-(in excess)
the strength of the Li--PEO
coordination lowered
the lithium mobility (Li+ conduction)
is promoted
1M. Castriota, T. Caruso, R. G. Agostino, E. Cazzanelli, W. A. Henderson, and S. Passerini,J. Phys. Chem. A 109 (2005) 922I. Nicotera, C. Oliviero, W. A. Henderson, G. B. Appetecchi, and S. PasseriniJ. Phys. Chem. B 109 (2005) 22814.
M. Joost et al Electrochim. Acta in ress 2012
PEO-LiX-IL electrolytes: Li interface (40C)
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y ( )
Impedance is localized at the Li/SPE interface
R1 R2
CPE1
CPE2
R3
W1 C1
R1 = bulk electrolyte resistance
R2 = Li/SPE interface 1CPE1 = Li/SPE interface 1
R3 = Li/SPE interface 2
CPE2 = Li/SPE interface 2
W1 = Warburg impedance
C1 = electrode limit capacitance0 150
___ Raw Data
___ Fit
Z
-jZ
Li / P(EO)20(LiTFSI)2(PYR14TFSI)n / Li
Transport properties by DC tests
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p p p y
How much current can be flown through the SPE?
Lithium
SPE
Galvanostatic and
Potentiostatic
experiments
Capacity of Li foil (Chemetall):
50 m * 1 cm = 5mm 10.32 mAh/cm
T t ti b l t ti t t (30 C)
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Transport properties by galvanostatic tests (30C)
IL containing electrolytes perform well at 30C
Dendrites due to
inhomogeneity of
ionic conduction
Li / P(EO)20(LiTFSI)2(PYR14TFSI)n / Li
Transport properties by potentiostatic tests (30 C)
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Transport properties by potentiostatic tests (30C)
Good agreement between galvanostatic and potentiostatic results
Li / P(EO)20(LiTFSI)2(PYR14TFSI)4 / Li
0.05 mAcm-2 @ 0.2 V
Transport properties by DC tests
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p p p y
Complete stripping of 50 m of lithium (ca. 10 mAh cm-2)
Li / P(EO)20(LiTFSI)2(PYR14TFSI)n / Li
bottom
lithium
SPE,
slightly
oxydised
Left overedge of top
lithium
Area of
stripped
lithium
Lithium
SPE
Transport properties by DC tests
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Opened cell after full lithium plating
Li / P(EO)20(LiTFSI)2(PYR14TFSI)n / Li
Open cell
SPE
Plated lithium
Transport properties by DC tests
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SEM of fresh lithium, plated lithium and SPE
Li / P(EO)20(LiTFSI)2(PYR14TFSI)n / Li
fresh lithium plated lithium SPE on stripped lithium
Conclusions
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Ionic Liquid mixtures with lithium salts as such and in
presence of polymers show very promising performance
as Li-ion conductors.
IL-based electrolytes:
easy to recycle (low volatility)
wide storage temperature rangelow flammability components
high temperature operation capability (>60C)
IL-based electrolytes appear promising for safe, high
energy and moderate power applications (such as full EV
and stationary storage).
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Acknowledgements
German and NRW funding agencies
The European Commission for the financial support of the projects:
ILLIBATT (Ionic Liquid based LIthium BATTeries)
LABOHR (Lithium Air Batteries with split Oxygen Harvesting and Reduction processes)
GREEN LION (Advanced Manufacturing Processes for Low Cost GREENerLi-IONBatteries)
All members of WWU-MEET and ENEA battery groups
Back up
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p
Methods
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Methods
relaxation measurements
1) spin-lattice-relaxation time T1:inversion recovery
2) spin-spin-relaxation time T2:
CPMG-sequence
diffusion measurements:
pulsed gradient stimulated echo
sequence
d1
180y90x
erstes
Echo
180y
zweites
Echo
usw.
first
ECHO
second
ECHO
d1
d1
180x 90x
90x
gg
markaspin
positionbythe
precessionphase
readthespin
positionafter
time
z1 z2
g:gradientstrength
:gradientduration
:diffusiontime
:evolutiontime
z1
andz2:spinpositionbeforeandafterthegradients
90x 90x
local motion macroscopic motion
Is the Li+ --- TFSI- ion-pairing avoidable?
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N+
CH3
CH3
Is the Li --- TFSI ion-pairing avoidable?
Pyr+14
Pyr+1(2O1)
Cation aggregation in ILs with polar side chains
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for systems with Li salt R does
not change
aggregation of cations w/ polar
group
cations do not aggregate when
a lithium salt is dissolved
pure IL IL with Li salt
N+
CH3
CH3
R2 dependent on chain length in pure systems
slow local motions influenced
R1 independent on chain length in pure systems
fast local motions not influenced
R changes with chain length
anisotropical arrangement
PYR+1A Li+TFSI- interactions
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Raman
Addition of oxygen into side
chain reduces the number of
TFSI anions in cluster.
Addition of oxygen into side
chain reduces the number of
TFSI anions in cluster.
Pyr14
TFSI
Pyr15
TFSI
free TFSI-
Li+ ---
TFSI-
Pyr1(2O1)T
FSI
Pyr1(2O2)T
FS
I
Diffusion coefficient
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diffusion of Li+ slower than those of
Pyr1A+ and TFSI-
coordination clusters hindered in
motion
difference of diffusion coefficientslarger for polar side chain than for
non-polar side chain
mobility of lithium ions not
enhanced by coordination of
pyrrolidinium cation
M. Kunze, et al., JPC C (2011)
N
+
CH3
CH3
Tailored Ionic Liquid for Lithium Batteries
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Purity > 99.5%
H2O < 1ppm
Td:
175C
RT: > 3 mS/cm
C: 1 mS/cm
ESW: > 5.0 V
PYR14FSI
Tm: -
18C
Paillard et al., JES 156, A891(2009), Kunze et al. JPC A 114, 1776 (2010)
Pyr+14 Li+TFSI- interactions
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y 14
NMR-chemical shift
NMR features of oxygen
neighbours are strongly affected as
a result of the Li --- IL Cation
interactions
Red:pure
IL
Black:ILwith salt
ILLIBATT Project achievements
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ILLIBATT Project achievements
7Page 7Page 9
Demonstrated feasibility of Ionic Liquid-based batteries at the pre-
industrial scale
ILLIBATT has been selected together with other most successfulprojects within the FP5 and FP6 calls
Materials for a sustainable chemistry
European Commission, Research Directorate-General
Directorate G-Industrial Technologies-Value-added Materials
ILLIBATT Cells:
Do not contain volatile components
Halides are present only in the easy-to-
recycle electrolyte
All binders are halide-free
Battery tests: PEO-IL-LiX electrolyte (near RT tests)
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Large capacities (140 mAhg-1) up to medium rates (C/5)
Moderate capacities (50-75 mAhg-1) even at high rates (2C-1C)
> 90% of initial capacity is delivered upon about 200 cycles
Li / P(EO)10LiTFSI-PYR14TFSI / LiFePO4
PEO-LiX-IL electrolytes: Li interface
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Excellent lithium plating/stripping performance
Lowered interface resistance
PEO : LiTFSI : PYR14TFSI = 20:2:4 (mol)
Lithium
electrodes
SPE
Plated Li SPEDepleted Li