NON-AQUEOUS ELECTROLYTE SOLUTION AND POWER STORAGE DEVICE USING SAME

There is provided a nonaqueous electrolytic solution for an energy storage device which is a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent and contains a phosphonate represented by the following general formula (I), and an energy storage device using the same:wherein, R1 represents an alkenyl group having 2 to 6 carbon atoms or an alkynyl group having 3 to 6 carbon atoms, and R2 and R3 each independently represent an alkynyl group having 3 to 6 carbon atoms.