ELECTROLYTE SOLUTION FOR LITHIUM ION SECONDARY BATTERY, METHOD FOR PRODUCING ELECTROLYTE SOLUTION FOR LITHIUM ION SECONDARY BATTERY, LITHIUM ION SECONDARY BATTERY USING THE ELECTROLYTE SOLUTION, AND POWER SUPPLY DEVICE USING LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of improving the fire retardancy of an electrolyte and suppressing reduction in battery capacity.SOLUTION: An electrolyte for a lithium ion secondary battery contains trimethyl phosphite, dimethyl phosphite, dimethyl phosphonate, and at least one kind of cyclic ester compounds represented by chemical formulas 1-4.