Patent ID: 8795884

Claim:
A nonaqueous secondary battery comprising a positive electrode including a positive electrode mixture layer, a negative electrode and a nonaqueous electrolyte, wherein the positive electrode mixture layer contains a lithium-containing complex oxide defined by the general formula (1) and has a density of 3.5 g/cm 3 or more, and the nonaqueous electrolyte contains a solvent, an electrolyte salt, and a fluorinated nitrile compound including two or more cyano groups in molecules or a cyano group and an ester group in molecules, or triethyl-2-fluoro-2-phosphono-acetate; Li x M 1 y M 2 z M 3 v O 2 (1) where, M 1 represents at least one transition metal element selected from the group consisting of Co, Ni and Mn, M 2 represents at least one metal element selected from the group consisting of Mg, Ti, Zr, Ge, Nb, Al and Sn, M 3 represents an element other than Li, M 1 and M 2 , 0.97≦x<1.02, 0.8≦y<1.02, 0.002≦z≦0.05, and 0≦v≦0.05, and an amount of the fluorinated nitrile compound added to the nonaqueous electrolyte is 0.005 to 1.0 mass %.