Nonaqueous electrolyte compositions comprising silyl oxalates

1. An electrolyte composition comprising:

a) a fluorinated solvent;

b) at least one silyl oxalate represented by Formula I:

RR′Si(C 2 O 4 )  (I),

wherein R, and R′ are each the same or different from each other and independently selected from C 1 -C 8 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, or C 6 -C 10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups; and

c) LiPF 6 .

2. The electrolyte composition of claim 1 , wherein the silyl oxalate comprises dimethylsilyl oxalate, vinylphenylsilyl oxalate, methylvinylsilyl oxalate, or diphenylsilyl oxalate.

3. The electrolyte composition of claim 1 , wherein the fluorinated solvent comprises:

a) a fluorinated acyclic carboxylic acid ester represented by the formula:

R 1 —COO—R 2 ,

b) a fluorinated acyclic carbonate represented by the formula:

R 3 —OCOO—R 4 ,

c) a fluorinated acyclic ether represented by the formula:

R 5 —O—R 6 ,

or mixtures thereof;

wherein

i) R 1 is H, an alkyl group, or a fluoroalkyl group;

ii) R 3 and R 5 is each independently a fluoroalkyl group and can be either the same as or different from each other;

iii) R 2 , R 4 , and R 6 is each independently an alkyl group or a fluoroalkyl group and can be either the same as or different from each other;

iv) either or both of R 1 and R 2 comprises fluorine; and

v) R 1 and R 2 , R 3 and R 4 , and R 5 and R 6 , each taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms.

4. The electrolyte composition of claim 3 , wherein the fluorinated acyclic carboxylic acid ester comprises CH 3 —COO—CH 2 CF 2 H, CH 3 CH 2 —COO—CH 2 CF 2 H, F 2 CHCH 2 —COO—CH 3 , F 2 CHCH 2 —COO—CH 2 CH 3 , CH 3 —COO—CH 2 CH 2 CF 2 H, CH 3 CH 2 —COO—CH 2 CH 2 CF 2 H, F 2 CHCH 2 CH 2 —COO—CH 2 CH 3 , CH 3 —COO—CH 2 CF 3 , CH 3 CH 2 —COO—CH 2 CF 2 H, CH 3 —COO—CH 2 CF 3 , H.COO—CH 2 CF 2 H, H—COO—CH 2 CF 3 , or mixtures thereof.

5. The electrolyte composition of claim 4 , wherein the fluorinated acyclic carboxylic acid ester comprises CH 3 —COO—CH 2 CF 2 H.

6. The electrolyte composition of claim 1 , further comprising an organic carbonate.

7. The electrolyte composition of claim 6 , wherein the organic carbonate comprises 4-fluoroethylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, vinylene carbonate, or mixtures thereof.

8. The electrolyte composition of claim 7 , wherein the organic carbonate comprises 4-fluoroethylene carbonate.

9. An electrolyte composition comprising:

a) a fluorinated solvent; and

b) a lithium oxalato phosphate salt represented by Formula III:

LiPF (6-2q) (C 2 O 4 ) q   (III)

wherein q is 1, 2 or 3;

wherein the oxalato phosphate salt comprises at least a portion that is derived from at least one silyl oxalate represented by Formula I:

RR′Si(C 2 O 4 )  (I),

wherein R and R′ are each the same or different from each other and independently selected from C 1 -C 5 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, or C 6 -C 10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups.

10. The electrolyte composition of claim 9 , wherein the silyl oxalate comprises dimethylsilyl oxalate, vinylphenylsilyl oxalate, methylvinylsilyl oxalate, or diphenylsilyl oxalate.

11. The electrolyte composition of claim 9 , wherein the fluorinated solvent comprises a fluorinated acyclic carboxylic acid ester comprising CH 3 —COO—CH 2 CF 2 H, CH 3 CH 2 —COO—CH 2 CF 2 H, F 2 CHCH 2 —COO—CH 3 , F 2 CHCH 2 —COO—CH 2 CH 3 , CH 3 —COO—CH 2 CH 2 CF 2 H, CH 3 CH 2 —COO—CH 2 CH 2 CF 2 H, F 2 CHCH 2 CH 2 —COO—CH 2 CH 3 , CH 3 —COO—CH 2 CF 3 , CH 3 CH 2 —COO—CH 2 CF 2 H, CH 3 —COO—CH 2 CF 3 , H.COO—CH 2 CF 2 H, H—COO—CH 2 CF 3 , or mixtures thereof.

12. The electrolyte composition of claim 11 , wherein the fluorinated acyclic carboxylic acid ester comprises CH 3 —COO—CH 2 CF 2 H.

13. The electrolyte composition of claim 9 , wherein the oxalato phosphate salt comprises lithium tris(oxalato)phosphate.

14. A method comprising:

a step of combining:

a) a fluorinated solvent;

b) at least one silyl oxalate represented by Formula I:

RR′Si(C 2 O 4 )  (I),

wherein R and R′ are each the same or different from each other and independently selected from C 1 -C 8 alkyl, C 2 -C 8 alkenyl, C 2 -C 8 alkynyl, or C 6 -C 10 aryl radical, optionally comprising at least one substituent selected from halogen, hydroxyl, alkoxy, carbonyl, and carboxyl groups; and

c) LiPF6;

to form an electrolyte composition.

15. An electrochemical cell comprising:

(a) a housing;

(b) an anode and a cathode disposed in the housing and in ionically conductive contact with one another;

(c) the electrolyte composition of claim 9 disposed in the housing and providing an ionically conductive pathway between the anode and the cathode; and

(d) a porous separator between the anode and the cathode.

16. The electrochemical cell of claim 15 , wherein the electrochemical cell is a lithium ion battery.

17. An electronic device, transportation device, or telecommunications device, comprising an electrochemical cell according to claim 15 .