Patent ID: 8679676

Claim:
A non-aqueous electrolyte secondary battery comprising: a positive electrode; a negative electrode; a microporous separator for providing electrical isolation between the positive electrode and the negative electrode, the microporous separator consisting essentially of polyethylene and having a porosity of 28 to 54% and an air permeability of 86 to 395 secs/dl; and a non-aqueous electrolyte containing an electrolyte salt, a nitrile compound, and a non-aqueous solvent containing a carboxylic acid ester, wherein: the carboxylic acid ester is selected from the group consisting of methyl trimethylacetate, ethyl trimethylacetate, 2,2-dimethyl methyl butyrate, methyl isobutyrate and ethyl isobutyrate; and the nitrile compound is selected from the group consisting of adiponitrile, succinonitrile, sebaconitrile, undecanedinitrile and butyronitrile; the non-aqueous solvent contains ethylene carbonate and 5 to 80% by mass of the carboxylic acid ester; and 0.3 to 5 parts by mass of the nitrile compound is added to 100 parts by mass of the non-aqueous solvent.