NONAQUEOUS ELECTROLYTE ADDITIVE, NONAQUEOUS ELECTROLYTE, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

The present invention relates to a non-aqueous electrolyte additive that allows for improved safety and battery characteristics of a non-aqueous electrolyte secondary battery, and in greater detail, the present invention relates to a non-aqueous electrolyte additive that includes at least one compound selected from a first compound group consisting of phosphazene compounds represented by the following general formula (1): (NPR) (1) wherein each R independently represents fluorine or a substituent including an organic group substituted with fluorine, at least one of the Rs represents the substituent including an organic group substituted with fluorine, and n is from 3 to 14; and includes at least one compound selected from a second compound group consisting of borate represented by the following general formula (2), bis(oxalato)borate, difluoro(oxalato)borate, tris(oxalato)phosphate, difluoro(bisoxalato)phosphate, and tetrafluoro(oxalato)phosphate: wherein Arepresents a cation, and a represents the valency of the cation.