Patent ID: 8026000

Claim:
A nonaqueous electrolyte secondary battery comprising: a positive electrode that has a positive electrode active material; a negative electrode; and a nonaqueous electrolyte that has electrolyte salt in a nonaqueous solvent; the electric potential of said positive electrode active material being 4.4 to 4.6 V relative to lithium, and said nonaqueous electrolyte containing a compound given by structural formula (I) below in a content of 0.1% to 2% by mass of said nonaqueous electrolyte, methyl ethyl carbonate content of 30% to 80% by volume, and LiPF 6 content of 1.0 mol/L to 2.0 mol/L in said nonaqueous solvent, and said positive electrode active material comprises a mixture of a lithium-cobalt composite oxide which is LiCoO 2 containing at least both zirconium and magnesium and a lithium-manganese-nickel composite oxide that has a layer structure and contains at least both manganese and nickel.