Electrolytic solution for nonaqueous electrolytic solution cell, and nonaqueous electrolytic solution cell

An electrolyte for nonaqueous electrolyte cells, which contains a nonaqueous organic solvent and a solute, wherein the electrolyte for nonaqueous electrolyte cells containing as additives:

• at least one compound selected from a first compound group consisting of bis(oxalato)borate, difluoro(oxalato)borate, tris(oxalato)phosphate, difluorobis(oxalato)phosphate, and tetrafluoro(oxalato)phosphate, and
• at least one compound selected from a second compound group consisting of a sulfonate group-containing imide salt, which is represented by the following general formula (I),
• M[R1OSO2NSO2OR2]n (I)
• wherein each of R1 and R2 independently represents at least one organic group selected from a C1-10 straight chain or branched alkyl group or alkenyl group, a C3-10 cycloalkyl group or cycloalkenyl group, and a C6-10 aryl group,
• a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group,
• M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and
• n represents an integer equal to valence of the corresponding cation.] and a phosphoryl group-containing imide salt represented by the following general formula (II),
• M[R3R4OPNPOR5R6]m (II)
• wherein each of R3, R4, R5 and R6 independently represents chlorine, fluorine or an organic group represented by —OR7;
• and R7 represents at least one organic group selected from a C1-10 straight chain or branched alkyl group or alkenyl group, a C3-10 cycloalkyl group or cycloalkenyl group,
• a C6-10 aryl group, and a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group,
• M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and
• m represents an integer equal to valence of the corresponding cation.]