LITHIUM-ION SECONDARY BATTERY

摘要

A lithium-ion secondary battery according to the present invention comprises a negative electrode that includes a negative-electrode active material which is capable of storing and discharging lithium ions, a positive electrode that includes a positive-electrode active material which is capable of storing and discharging the lithium ions, and an electrolyte that is formed by dissolving an electrolyte with a solvent. The solvent of the electrolyte contains fluorinated ethylene carbonate. The electrolyte contains a compound expressed in the following (1) as an additive. The mol concentration of the additive for each liter of the electrolyte is larger than zero mol per liter and smaller than 0.05 mol per liter. The lithium-ion secondary battery that has the above-described configuration has excellent charging and discharging cycle characteristics (M is P or B, X is a halogen group, R is a chain hydrocarbon group, n1 is one or two, n2 is an integer between one and four, and n3 is an integer between zero and three).