Nonaqueous electrolyte solution, electricity storage device using same, and phosphonoformic acid compound used in same

Abstract

The present invention provides a nonaqueous electrolytic solution capable of suppressing worsening of heat stability of a negative electrode and improving safety of an energy storage device while maintaining high-load charging and discharging cycle properties at a high temperature, an energy storage device using the same, and a phosphonoformic acid compound to be used for the same. The nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent contains 0.001 to 5% by mass of at least one selected from a phosphonoformic acid compound having at least one carbon-carbon unsaturated bond, which is represented by the following general formula (I), and a phosphonoformic acid compound having a carbon-carbon unsaturated bond or two phosphonocarbonyl groups, which is represented by the following general formula (II). In the formula (I), each of Rto Ris an aliphatic organic group, provided that at least one of Rto Rrepresents a carbon-carbon unsaturated bond-containing aliphatic organic group. In the formula (II), each of Rand Rrepresents an alkyl group, a cycloalkyl group, or an aryl group, and Rand Rmay be bonded to each other to form a ring structure. m represents 1 or 2; when m is 1, then Rrepresents an aryl group; when m is 2, then Rrepresents an alkylene group, an alkenylene group, or an alkynylene group; and a part of hydrogen atoms of Rto Rmay be substituted with a halogen atom.