Electrolyte compositions for lithium ion batteries

1. An ionic liquid of the general formula Y + T − , wherein Y + is a positively-charged component of the ionic liquid and Z − is a negatively-charged component of the ionic liquid, wherein Z − has a composition of the following formula:

wherein R 28 , R 29 , R 30 , and R 31 are independently selected from H, F, hydrocarbon groups R attaching to the shown boron atom by a carbon atom, and alkoxy groups —OR, wherein at least one of R 30 and R 31 is F, and R 28 and R 29 can optionally interconnect to form a boron-containing ring;

provided that, if R 28 and R 29 interconnect, then the ionic liquid has the formula:

wherein R 32 and R 33 are independently selected from H, F, hydrocarbon groups R, and alkoxy groups —OR, wherein at least one of R 32 and R 33 is F.

2. The ionic liquid of claim 1 , wherein Z − has a composition of the following formula:

3. The ionic liquid of claim 1 , wherein Y + is an ammonium or phosphonium species.

4. The ionic liquid of claim 3 , wherein Y + is an ammonium species.

5. The ionic liquid of claim 4 , wherein Y + is comprised of a heterocyclic ring having a positively-charged ring nitrogen.

6. The ionic liquid of claim 5 , wherein Y + is selected from imidazolium, benzimidazolium, pyridinium, pyrazinium, pyrrolidinium, piperidinium, piperazinium, morpholinium, pyrrolium, pyrazolium, pyrimidinium, triazolium, oxazolium, thiazolium, triazinium, indolium, quinolinium, quinazolinium, and cyclic guanidinium rings.

7. An electrolyte composition for a lithium ion battery, the electrolyte composition comprising:

a first ionic liquid of the general formula Y + Z − , wherein Y + is a positively-charged component of the ionic liquid and Z − is a negatively-charged component of the ionic liquid, wherein Z − has a composition of the following formula:

wherein R 28 , R 29 , R 30 , and R 31 are independently selected from H, F, hydrocarbon groups R attaching to the shown boron atom by a carbon atom, and alkoxy groups —OR, wherein at least one of R 30 and R 31 is F, and R 28 and R 29 can optionally interconnect to form a boron-containing ring,

provided that, if R 28 and R 29 interconnect, then the ionic liquid has the formula:

wherein R 32 and R 33 are independently selected from H, F, hydrocarbon groups R, and alkoxy groups —OR, wherein at least one of R 32 and R 33 is F;

a second ionic liquid of the general formula Y + X − , wherein Y + is a positively-charged component of the ionic liquid and X − is a negatively-charged component of the ionic liquid, wherein X − does not have a formula according to Formula 10a; and

a lithium salt.

8. An electrolyte composition for a lithium ion battery, the electrolyte composition comprised of:

an ionic liquid of the general formula Y + Z − , wherein Y + is a positively-charged component of the ionic liquid and Z − is a negatively-charged component of the ionic liquid, wherein Z − has a composition of the following formula:

wherein R 28 , R 29 , R 30 , and R 31 are independently selected from H, F, hydrocarbon groups R attaching to the shown boron atom by a carbon atom, and alkoxy groups —OR, wherein at least one of R 30 and R 31 is F, and R 28 and R 29 can optionally interconnect to form a boron-containing ring;

provided that, if R 28 and R 29 interconnect, then the ionic liquid has the formula:

wherein R 32 and R 33 are independently selected from H, F, hydrocarbon groups R, and alkoxy groups —OR, wherein at least one of R 32 and R 33 is F;

a non-ionic solvent; and

a lithium salt.

9. The electrolyte composition of claim 8 , wherein said non-ionic solvent is a sulfone or carbonate solvent.

10. The electrolyte composition of claim 8 , further comprising a non-ionic solvent additive.

11. The electrolyte composition of claim 10 , wherein said non-ionic solvent additive is a carbonate solvent additive.

12. The electrolyte composition of claim 10 , wherein said non-ionic solvent additive is a sulfite solvent additive.