Nonaqueous electrolytes and nonaqueous-electrolyte secondary batteries employing the same

摘要

A nonaqueous electrolyte containing a monofluorophosphate and/or a difluorophosphate and a compound having a specific chemical structure or specific properties. The nonaqueous electrolyte can contain at least one of a saturated chain hydrocarbon, a saturated cyclic hydrocarbon, an aromatic compound having a halogen atom and an ether having a fluorine atom.

主权项

1. A nonaqueous electrolyte mainly comprising a nonaqueous solvent and an electrolyte dissolved therein, wherein the nonaqueous electrolyte comprises at least one compound selected from the group consisting of saturated chain hydrocarbons, saturated cyclic hydrocarbons and ethers having a fluorine atom, and further comprises at least one metal salt of at least one of a monofluorophosphate and a difluorophosphate,
wherein the at least one compound selected from the group consisting of saturated chain hydrocarbons, saturated cyclic hydrocarbons and ethers having a fluorine atom is contained in a total amount of 0.01-15% by mass based on the total mass of the nonaqueous electrolyte, wherein the metal salt of the monofluorophosphate and/or difluorophosphate is contained in a total amount of from 0.001% by mass to 5% by mass based on the total mass of the nonaqueous electrolyte, and wherein the saturated chain hydrocarbons have 5-20 carbon atoms, the saturated cyclic hydrocarbons have 3-20 carbon atoms, and the ethers having a fluorine atom are expressed by a general formula R5—O—R6, in which the R5 is an alkyl group having 1-20 carbon atoms substituted with 1-30 fluorine atoms, and R6 is an alkyl group which has 1-20 carbon atoms and may have be substituted with substituents.