Nonaqueous electrolyte compositions comprising lithium glycolatoborate and fluorinated solvent

1. An electrolyte composition comprising:

a) from 10% to 80% by weight of a non-fluorinated carbonate selected from ethylene carbonate, propylene carbonate, or mixtures thereof;

b) from 10% to 90% by weight of a fluorinated solvent selected from fluorinated acyclic carboxylic acid esters represented by the formula R 1 —COO—R 2 wherein

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

ii) R 2 is an alkyl group or a fluoroalkyl group;

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

iv) R 1 and R 2 taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms;

c) from 0.01% to 5% by weight of lithium difluoro(glycolato) borate;

d) from 0.01 to 10% by weight of fluoroethylene carbonate; and

e) an electrolyte salt.

2. The electrolyte composition of claim 1 , wherein R 1 and R 2 taken as a pair, further comprise at least two fluorine atoms, with the proviso that none of R 1 nor R 2 contains a —CH 2 F or —CHF— group.

3. The electrolyte composition of claim 1 , wherein the fluorinated acyclic carboxylic acid ester is CH 3 —COO—CH 2 CF 2 H, CH 3 CH 2 —COOCH 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 —COOCH 2 CF 3 , CH 3 CH 2 —COO—CH 2 CF 2 H, or mixtures thereof.

4. The electrolyte composition of claim 1 , wherein the electrolyte composition comprises about 0.5 weight percent to about 5 weight percent of fluoroethylene carbonate, based on the weight of the electrolyte composition.

5. 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) electrolyte composition of claim 1 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.

6. The electrochemical cell of claim 5 , wherein said electrochemical cell is a lithium ion battery.

7. The electrochemical cell of claim 5 , wherein the anode comprises an anode active material and the anode active material is lithium titanate or graphite.

8. The electrochemical cell of claim 5 , wherein the cathode comprises a cathode active material exhibiting greater than 30 mAh/g capacity in the potential range greater than 4.6 V versus a Li/Li+ reference electrode.

9. The electrochemical cell of claim 5 , wherein the cathode comprises a cathode active material which is charged to a potential greater than or equal to 4.35 V versus a Li/Li+ reference electrode.

10. The electrochemical cell of claim 5 , wherein the cathode active material comprises:

a) a lithium-containing manganese composite oxide having a spinel structure as active material, the lithium-containing manganese composite oxide comprising oxides of the formula

Li x Ni y M z Mn 2−y−z O 4−d

wherein x is 0.03 to 1.0; x changes in accordance with release and uptake of lithium ions and electrons during charge and discharge; y is 0.3 to 0.6; M comprises one or more of Cr, Fe, Co, Li, Al, Ga, Nb, Mo, Ti, Zr, Mg, Zn, V, and Cu; z is 0.01 to 0.18, and d is 0 to 0.3; or

b) a composite material represented by the formula:

x(Li 2−w A 1−v Q w+v O 3−e )·(1−x)(Li y Mn 2−z M z O 4−d )

wherein:

x is about 0 to about 0.1;

A comprises one or more of Mn or Ti;

Q comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Mg, Nb, Ni, Ti, V, Zn, Zr or Y;

e is 0 to about 0.3;

v is 0 to 0.5;

w is 0 to about 0.6;

M comprises one or more of Al, Ca, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Nb, Ni, Si, Ti, V, Zn, Zr or Y;

d is 0 to about 0.5;

y is about 0 to about 1;

z is about 0.3 to about 1; and

wherein the Li y Mn 2−z M z O 4−d component has a spinel structure and the Li 2−w Q w+v A 1−v O 3−e component has a layered structure; or

c) a composition of the formula Li a Ni b Mn c Co d R e O 2−f Z f , wherein:

R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof, and Z is F, S, P, or a combination thereof; and 0.8≤a≤1.2, 0.1≤b≤0.9, 0.0≤c≤0.7, 0.05≤d≤0.4, 0≤e≤0.2; wherein the sum of b+c+d+e is about 1; and 0≤f≤0.08; or

d) a composition of the formula Li a A 1−x R x DO 4−f Z f , wherein:

A is Fe, Mn, Ni, Co, V, or a combination thereof;

R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof;

D is P, S, Si, or a combination thereof;

Z is F, Cl, S, or a combination thereof;

0.8≤a≤2.2;

0≤x≤0.3; and

0≤f≤0.1; or

e) a composition of the formula Li a A 1−b ,R b D 2 , wherein:

A is Ni, Co, Mn, or a combination thereof;

R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Zr, Ti, a rare earth element, or a combination thereof;

D is 0, F, S, P, or a combination thereof; and

0.90≤a≤1.8 and 0≤b≤0.5.

11. An electronic device, transportation device, or telecommunications device, comprising the electrochemical cell of claim 5 .

12. A method comprising combining:

a) from 10% to 80% by weight of a cyclic non-fluorinated carbonate selected from ethylene carbonate, propylene carbonate, or mixtures thereof;

b) from 10% to 90% by weight of a fluorinated solvent selected from fluorinated acyclic carboxylic acid esters represented by the formula R 1 —COO—R 2 wherein

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

ii) R 2 is an alkyl group or a fluoroalkyl group;

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

iv) R 1 and R 2 taken as a pair, comprise at least two carbon atoms but not more than seven carbon atoms;

c) from 0.01% to 5% by weight of lithium difluoro(glycolato) borate;

d) from 0.01 to 10% by weight of fluoroethylene carbonate; and

e) an electrolyte salt;

to form an electrolyte composition.