NONAQUEOUS ELECTROLYTE FOR SECONDARY BATTERY AND NONAQUEOUS-ELECTROLYTE SECONDARY BATTERY EMPLOYING THE SAME

A nonaqueous electrolyte secondary battery having excellent discharge load characteristics and are excellent in high-temperature storability, cycle characteristics, high capacity, continuous-charge characteristics, storability, gas evolution inhibition during continuous charge, high-current-density charge/discharge characteristics, discharge load characteristics is provided. The battery contains a negative electrode having an active material comprising Si or a Si alloy; a positive electrode; and a nonaqueous electrolyte solution, containing an electrolyte; a nonaqueous solvent including an acyclic carbonate having a halogen atom; and at least one compound selected from the group consisting of a monofluorophosphate and a difluorophosphate. A nonaqueous electrolyte in contact with a negative electrode having an active material comprising Si or a Si alloy is also provided.