Patent ID: 7998615

Claim:
A secondary battery comprising: a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte, characterized in that, the nonaqueous electrolyte comprises a room temperature molten salt, a fluorohydrocarbon and a lithium salt, wherein the room temperature molten salt consists of an onium cation and a non-aluminate anion, the onium cation is at least one selected from the group consisting of quaternary ammonium, imidazolium, pyridinium, pyrrolidinium, 1-propyl-1-methylpiperidinium, phosphonium and sulfonium cations; and when said onium cation is quaternary ammonium, the room temperature molten salt is Trimethylpropylammonium·bis[trifluoromethanesulfonyl]imide, and when said onium cation is pyridinium, the room temperature molten salt is n-butyl-pyridinium·tetrafluoroborate, and wherein said fluorohydrocarbon is at least one selected from the group consisting of monofluoro-alkane and monofluoro-cycloalkane.