NONAQUEOUS SOLVENT, AND NONAQUEOUS ELECTROLYTE SOLUTION AND NONAQUEOUS SECONDARY BATTERY THAT USE NONAQUEOUS SOLVENT

摘要

The nonaqueous solvent for a nonaqueous secondary battery of the present invention includes: a fluorinated cyclic carbonate having at least one fluorine in each designated location in the molecule; and a fluorinated phosphazene having at least one fluorine bound to a phosphorus atom in the phosphazene molecule and a ratio of the number of fluorine atoms to the number of phosphorus atoms being 4/3 or more. The fluorinated cyclic carbonate forms a good protective coat by reductive decomposition at a negative electrode, thereby improving cycle characteristics of the nonaqueous secondary battery. The fluorinated phosphazene suppresses generation of organic ions in the nonaqueous solvent, thereby reducing gas production in the nonaqueous secondary battery.