WIDE TEMPERATURE RANGE ULTRACAPACITOR

1 . A solid state electrolyte for use in an ultracapacitor comprising:

a polymer matrix doped with an ionic liquid and two solvents-a first solvent and a second solvent; where the second solvent has a melting point lower than the first solvent; where the first solvent has a dielectric constant at 25° C. greater than about 2; and

wherein an ultracapacitor that utilizes the electrolyte is configured to output electrical energy at temperatures throughout an operating temperature range.

2 . The electrolyte of claim 1 , wherein the operating temperature range comprises 0 degrees Celsius to 275 degrees Celsius.

3 . The electrolyte of claim 1 , wherein the ultracapacitor that utilizes the electrolyte is configured to output electrical energy at operating voltages throughout an operating voltage range, the operating voltage range being between about 0 V and about 0.5 V.

4 . The electrolyte of claim 1 , where the solid state electrolyte is cast directly onto an electrode in the ultracapacitor.

5 . The electrolyte of claim 1 , where the first solvent comprises acetonitrile, trimethylamine, propylene carbonate or gamma-butyrolactone.

6 . The electrolyte of claim 1 , where the second solvent comprises methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile or 1,3-dioxolane.

7 . The electrolyte of claim 1 , where the second solvent may has a melting point that is lower than the boiling point of the first solvent by at least 10° C.

8 . The electrolyte of claim 1 , wherein the ionic liquid comprises a cation comprising at least one of: tetrabutylammonium, 1-(3-cyanopropyl)-3-methylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1,3-bis(3-cyanopropyl)imidazolium, 1,3-diethoxyimidazolium, 1-butyl-1-methylpiperidinium, 1-butyl−2,3-dimethylimidazolium, 1- butyl-3-methylimidazolium, 1-butyl-4-methylpyridinium, 1-butylpyridinium,1-decyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-hexyl-3- methylimidazolium, 3-methyl-1-propylpyridinium, or a combination thereof.

9 . The electrolyte of claim 1 , wherein the ionic liquid comprises a cation comprising at least one of: ammonium, imidazolium, pyrazinium, piperidinium, pyridinium, pyrimidinium, and pyrrolidinium and combinations thereof

10 . The electrolyte of claim 1 , wherein the ionic liquid comprises a anion comprising at least one of: bis(trifluoromethanesulfonate)imide, tris(trifluoromethanesulfonate)methide, dicyanamide, tetrafluoroborate, tetra(cyano)borate, hexafluorophosphate, tris(pentafluoroethyl)trifluorophosphate, trifluoromethanesulfonate, bis(pentafluoroethanesulfonate)imide, thiocyanate, trifluoro(trifluoromethyl)borate, and combinations thereof.

11 . The electrolyte of claim 1 , further comprising at least one additive.

12 . The electrolyte of claim 11 , wherein the additive comprises a porous inorganic oxide.

13 . The electrolyte of claim 12 , wherein the porous inorganic oxide comprises at least one of silica, silicates, alumina, titania, magnesia, aluminosilicates, zeolites, titanates, or combinations thereof.

14 . The electrolyte of claim 11 , wherein the additive comprises silica or silicates.

15 . The electrolyte of claim 11 , wherein the additive comprises a mesoporous inorganic oxide.

16 . The electrolyte of claim 11 , wherein the additive comprises a gelling agent that comprises a polycrystalline inorganic oxide.

17 . The electrolyte of claim 11 , wherein the additive comprises a gelling agent that comprises a microcrystalline inorganic oxide.

18 . The electrolyte of claim 11 , wherein the additive comprises a material with a specific surface area (SSA) above about 400 m 2 /g.

19 . The electrolyte of claim 1 , wherein the ultracapacitor that utilizes the electrolyte is configured to output electrical energy at operating voltages throughout an operating voltage range, the operating voltage range being between about 0 V and about 0.5 V.

20 . The electrolyte of claim 1 , wherein at least one solvent of the two solvents is a gas at 0° C. and 760 mm Hg.