Development of Novel Development of Novel Lithium Salts for Lithium Salts for

Battery ApplicationsBattery Applications

1. Introduction – searching for new salts for lithium batteries

2. Synthesis and characterization of novel family of organic covalent lithium salts

3. Properties of polymer and liquid electrolytes containing newly developed salts:

• conductivity • lithium transference number• formation of ionic aggregates• electrochemical stability • performance in lithium batteries

4. Conclusions

Outline of the presentation

Anions:

• are an important part of SEI build-upat +/- electrodes

• Control transport numbers t+ /t-

• Control dissociation and conductivity

• Control aluminium corrosion

AsF6-

BF4-

PF6- SbF6

-

ClO4-

Classics…Classics…

Tendency to décompose according to equilibrium:LiBF4 BF3 + <LiF>

LiPF6 PF5 + <LiF>Fast reaction above 80°C

Destruction of electrolyte and interfaces

Explosive ! Toxic !

Conceptual approach to anion design

“N, C” are favorable:

Weak interactions Li—N but easy oxidation

“O” is not a favorable building block:

Strong Li—O interactions ion pairing, ≠ ClO4-, BOB-

If O present, F or CnF2n+1 is required

Stability Domains

Li4Ti5PO12

LiV3O8

LiMnPO4

LiFePO4

LiCoPO4

Li metal

LiMO2 mixed oxides

Graphite

Fluorinated anions

Non fluorinated anions

Hückel anions…

X = N, C-CN, CRF, S(O)RF

See P. Johansson et alPhysical Chemistry Chemical Physics, volume 6, issue 5, (2004).

Aromaticity 4n + 2 «  » electrons

pKA = 10-60 pKA = 10-20

Gain of > 1 eV by resonance

LiDCTA

NN

N

CNNC

-

DCTA

Stable to 3.8 V (La Sapienza, KZ) inexpensive

NH2H2N

CNNC

ON

O-

NC CN

NN

N--2H2O

Gives quite fluid ILs N

NC CN

NN

N-

Most Stable Lithium Imidazole Configurations

LiTDI LiPDI

B3LYP/6-311+G(d)Scheers et al. 2009

1.88 Å1.87 Å

1.92 Å

1.93 Å

LiTDI < LiPDI < LiDCTA < LiTFSI < LiPF6

Gas Phase Ion Pair Dissociation Energies

Ion pair (g) Li+ (g) + Anion- (g)

MP2/6-31G(d)

LiTDI LiPDI LiDCTA LiTFSI LiPF6 Scheers et al. 2009

LiTDI (2-trifluoromethyl-4,5-LiTDI (2-trifluoromethyl-4,5-dicyanoimidazole lithium salt)dicyanoimidazole lithium salt)

C

CN

C

N-

CF3

C

C

N

N

Li+

d io x a n e / T

+ L i2 C O 3 / w a te r

C NH2

NH2CN

N O

C

O

C

O

CF3

CF3

+

- 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;

New saltsNew salts

- NN

CF3

N N

- NN

C2F5

N N

- NN

n-C3F7

N N

-

N

NN

N

CF3

Li+

Li+

Li+

Li+

LiTDI LiPDI LiHDI

LiTPI

Conductivity in PEO

2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.51E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

cond

uctiv

ity / -1

cm-1

1000/T / K-1

DCTA PDI TDI

SS / PEO20LiX / SS

cooling scan

LiDCTALiPDILiTDI

LiHDI-PEO ConductivityLiHDI-PEO Conductivity

1:25 Ea=76.4 kJ∙mol-1 1:50 Ea=121.8 kJ∙mol-1

-8

-7

-6

-5

-4

-3

2,9 3 3,1 3,2 3,3 3,4 3,5

1000·T-1 / K-1

log(

σ / S

·cm

-1)

1:25 Li/O1:50 Li/O

N

NN

NC CN

Li+

2.4 2.6 2.8 3.0 3.2 3.4 3.61E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

T/°C2139,460,184

C

ondu

cibi

lità

/ S

cm-1

x: 10%

1000T-1 / K-1

111,5

x: 0%

PEO20LiCF3SO3+ ZrO2SACasting

PEO20LiDCTAHot-Pressing

2.4 2.6 2.8 3.0 3.2 3.4 3.61E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.0121

T / °C39,460,184111,5

Cond

ucib

ilità

/ Sc

m-1

1000T-1 / K-1

PEO20

LiBOB

PEO20

LiBF4

PEO20LiBOB/ LiBF4

Hot-Pressing

2.4 2.6 2.8 3.0 3.2 3.4 3.61E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.0121

T / °C39,460,184111,5

Con

duci

bilit

à / S

cm-1

1000T-1 / K-1

PEO20

LiDCTA

PEO20

LiBF4

2.6 2.8 3.0 3.21E-6

1E-5

1E-4

1E-3

0.01

Conduct

ivity

S

/ cm

1000 / T K-1

PEO 20

A

PEO 20

B

PEO20LiTDIPEO20LiPDI

Hot-PressingPEO20LiTDIPEO20LiPDI

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5

0.00

0.05

0.10

0.15

0.20

curr

ent /

mA

/cm

2

Potential / V

DCTA PDI TDI

Li / PEO20LiX / Super P

Anodic breakdown voltage vs. Li

P(EO)20LiDCTA 3.6V

P(EO)20LiPDI 4.0V

P(EO)20LiTDI 4.0V

Anodic stability

LiDCTALiPDILiTDI

0 40 80 120 160 2000

-20

-40

-60

-80

-100

Zim

m /

Ohm

Zreal / Ohm

2h 4.5h 7h 1d 2d 5d 7d 12d

0 40 80 120 160 2000

-20

-40

-60

-80

-100

Zim

m /

Ohm

Zreal / Ohm

2h 4.5h 7h 1d 2d 5d 7d 12d

0 40 80 120 160 2000

-20

-40

-60

-80

-100

Zim

m /

Ohm

Zreal / Ohm

2h 4.5h 7h 1d 2d 5d 7d 12d

LiPDI

LiTDILiDCTA

Li / PEO20LiX / Li

Interphase resistance - PEO

0 3 6 9 12 150

40

80

120

160

200

240

resi

stan

ce /

Ohm

time / d

PDIa PDIb TDIa TDIb DCTAa DCTAb

Interphase resistance - PEOLi / PEO20LiX / Li

LiPDIaLiPDIbLiTDIaLiTDIbLiDCTAaLiDCTAb

Cycling behaviour

Rate capability (PEO)

% o

f ca

paci

ty a

t C

/20

Rate capability (PEO)

% o

f ca

paci

ty a

t C

/20

LiLiTDI-PEGDME500 ConductivityTDI-PEGDME500 Conductivity

-6

-5,5

-5

-4,5

-4

-3,5

-3

-2,5

2,9 3 3,1 3,2 3,3 3,4 3,5 3,6

1000·T-1 / K-1

log(

σ / S

·cm

-1)

2M1M0.33M0.1M0.033M0.01M

Transference numbers in Transference numbers in PEGDME 500PEGDME 500

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

-1 0 1 2 3 4 5

-log(c / mol·dm-3)

t +

LiTDI

LiPDI

LiHDI

Cation transference number vs. Cation transference number vs. Ionic conductivity (PEGDME 500)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-PEGDME500LiTDI-PEGDME500Stability vs. Lithium against timeStability vs. Lithium against time

0

200

400

600

800

0 200 400 600 800t / h

R /

Ω·c

m-1

1. sample2. sample3. sample

LiLiTDI-PC ConductivityTDI-PC Conductivity

-5

-4,5

-4

-3,5

-3

-2,5

2,9 3 3,1 3,2 3,3 3,4 3,5 3,6

1000·T-1 / K-1

log(

σ / S

·cm

-1)

1M0.25M0.1M0.033M0.01M0.0033M0.001M

LiLiHDI-PC ConductivityHDI-PC Conductivity

-5,5

-5

-4,5

-4

-3,5

-3

-2,5

2,9 3 3,1 3,2 3,3 3,4 3,5 3,6

1000·T-1 / K-1

log(

σ / S

·cm

-1)

1M0.33M0.1M0.033M0.01M0.0033M0.001M0.00033M

LiLiTDI-PC Molar ConductivityTDI-PC Molar Conductivity

0

10

20

30

40

50

0 0,2 0,4 0,6 0,8 1

c0.5 / mol0.5·dm-1.5

Λ /

S·c

m2 ·m

ol-1

20°C40°C60°C

LiLiHDI-PC Molar ConductivityHDI-PC Molar Conductivity

0

2

4

6

8

10

12

0 0,2 0,4 0,6 0,8 1

c0.5 / mol0.5·dm-1.5

Λ /

S·c

m2 ·m

ol-1

20°C40°C60°C

LiTDI-PC Fuoss-Kraus formalismLiTDI-PC Fuoss-Kraus formalism association estimation association estimation

0

20

40

60

80

100

0 1 2 3 4 5

-log(c) / mol·dm-3

% o

f io

ns /

ion

pair

s / t

ripl

ets.

ion pairstriplets"free" ions

LiLiHDI-PC Fuoss-Kraus formalismHDI-PC Fuoss-Kraus formalism association estimation association estimation

0

20

40

60

80

100

0 1 2 3 4 5

-log(c) / mol·dm-3

% o

f io

ns /

ion

pair

s / t

ripl

ets.

"free" ionsion pairstriplets

Transference NumberTransference Numberss in PC in PC

0,0

0,1

0,2

0,3

0,4

0,5

0 1 2 3 4 5

-log(c / mol·dm-3)

t +

LiTDILiPDILiHDI

Salts-PC Stability vs. LithiumSalts-PC Stability vs. Lithium

-0,1

-0,08

-0,06

-0,04

-0,02

0

0,02

0,04

0,06

0,08

0,1

0 1 2 3 4 5

E / V vs. Li

j / m

A·c

m-2

LiTDILiPDILiHDI

LiTDI LiTDI Conductivity in EC:DMCConductivity in EC:DMC

-4

-3,5

-3

-2,5

-2

-1,5

2,9 3 3,1 3,2 3,3 3,4 3,5 3,6

1000·T-1 / K-1

log(

σ / S

·cm

-1)

1M0.33M0.1M0.033M0.01M

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 saltsNew 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 PEGDME50010‑6 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 saltsResearch team working on new salts

Presentation of research teamworking on new lithium salts:

Warsaw University of Technology: - - L. NiedzickiL. Niedzicki and W. WieczorekW. Wieczorek – characterization of salts and low molecular weight polyether electrolytes- - J. PrejznerJ. Prejzner, P. SzczecińskiP. Szczeciński, M. BukowskaM. Bukowska - synthesis of new salts- - Z. ŻukowskaZ. Żukowska – spectroscopic studies

Universite de Picardie Jules Verne, Laboratoire de Reactivite et de Chimie des Solides- - S. GrugeonS. Grugeon, S. LaruelleS. Laruelle - characterization of solid polymeric electrolytes, studies of electrochemical stability and battery performance- and M. ArmandM. Armand – development of new salt systems

Faculty of Chemistry, University of Rome, “ La Sapienza- - S. PaneroS. Panero, P. RealeP. Reale and B. ScrosatiB. Scrosati, - characterization of solid polymeric electrolytes; conductivity, transference numbers and electrochemical stability

Department of Applied Physics, Chalmers University of Technology, - - J. ScheersJ. Scheers, P. JohanssonP. Johansson, P. JacobssonP. Jacobsson – modeling and spectroscopic studies

For inquiries about For inquiries about buying LiTDIbuying LiTDI

(lithium 4,5-dicyano-2-(lithium 4,5-dicyano-2-(trifluoromethyl)imidazolate)(trifluoromethyl)imidazolate)

please contact:please contact:Leszek NiedzickiLeszek Niedzicki

asalm@ch.pw.edu.plasalm@ch.pw.edu.pl

- NN

CF3

N N

Li+

LiTDI