Nonaqueous electrolyte compositions comprising lithium malonatoborate and fluorinated solvent

1. An electrolyte composition comprising:

a) a non-fluorinated carbonate selected from ethylene carbonate, propylene carbonate, and mixtures thereof;

b) a fluorinated solvent comprising at least 2,2-difluoroethylacetate;

c) a lithium bis(malonato) borate compound selected from bis(2,2-dimethylmalonato) borate, bis(malonato) borate, bis(ethylmethylmalonato) borate, or bis(allylmalonato) borate;

d) a fluorinated carbonate different from the fluorinated solvent and which comprises fluoroethylene carbonate; and

e) an electrolyte salt.

2. The electrolyte composition of claim 1 , wherein the non-fluorinated carbonate comprises ethylene carbonate.

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

a) a fluorinated acyclic carbonate represented by the formula:

R 3 —OCOO—R 4 ,

b) a fluorinated acyclic ether represented by the formula:

R 5 —O—R 6 ,

or a mixture thereof;

wherein

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

ii) 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; and

iii) 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 R 3 and R 4 , and R 5 and R 6 , each taken as a pair, further comprise at least two fluorine atoms, with the proviso that none of R 3 , R 4 , R 5 , nor R 6 contains a —CH 2 F or —CHF— group.

5. The electrolyte composition of claim 1 , wherein the fluorinated solvent further comprises 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.

6. The electrolyte composition of claim 1 , wherein the electrolyte composition comprises about 0.5 weight percent to about 5 weight percent of a cyclic fluorinated carbonate and 0.01 weight percent to 5 weight percent of a lithium bis(malonato) borate, based on the weight of the electrolyte composition.

7. 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 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.

8. The electrochemical cell of claim 7 , wherein the electrochemical cell is a lithium ion battery.

9. The electrochemical cell of claim 8 , wherein the anode comprises an anode active material and the anode active material is lithium titanate or graphite.

10. The electrochemical cell of claim 8 , 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.

11. The electrochemical cell of claim 8 , 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.

12. The electrochemical cell of claim 8 , 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 about 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 ReO 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 O, F, S, P, or a combination thereof; and 0.90≤a≤1.8 and 0≤b≤0.5.

13. An electronic device, transportation device, or telecommunications device, comprising the electrochemical cell of claim 7 .

14. A method comprising combining:

a) a non-fluorinated carbonate selected from ethylene carbonate, propylene carbonate, and mixtures thereof;

b) a fluorinated solvent comprising at least 2,2-difluoroethylacetate;

c) a lithium bis(malonato) borate compound selected from bis(2,2-dimethylmalonato) borate, bis(malonato) borate, bis(ethylmethylmalonato) borate, or bis(allylmalonato) borate;

d) a fluorinated carbonate different from the fluorinated solvent and which comprises fluoroethylene carbonate; and

e) an electrolyte salt;

to form an electrolyte composition.