Non-aqueous electrolyte secondary battery including an electrolyte containing a fluorinated cyclic carbonate and carboxylic ester as a solvent and a nitrile compound as an additive

A non-aqueous electrolyte secondary battery comprising:

• a positive electrode;
• a negative electrode;
• a separator interposed between the positive electrode and the negative electrode;
• and a non-aqueous electrolyte solution in which a solute is dissolved in a non-aqueous solvent, wherein:
• the positive electrode comprises a positive electrode active material which is a lithium cobalt oxide to which zirconium is added;
• the negative electrode comprises a negative electrode active material capable of alloying with lithium;
• the non-aqueous solvent of the non-aqueous electrolyte solution consists of (a) one or more fluorinated cyclic carbonates selected from the group consisting of 4-fluoro-1,3-dioxolane-2-one and 4,5-difluoro-1,3-dioxolane-2-one and (b) a carboxylic ester;
• the non-aqueous electrolyte solution contains a nitrile compound having a chain saturated hydrocarbon group having two or more carbon atoms;
• and wherein the negative electrode active material capable of alloying with lithium is a material containing silicon.