Patent ID: 7583058

Claim:
A method of charging a lithium ion secondary battery, the lithium ion secondary battery comprising 1) a positive electrode that includes a mixed metal oxide containing at least Li, Mn, and Ni as metal components as a positive electrode active material, 2) a negative electrode, and 3) a nonaqueous electrolytic solution containing a lithium salt, the method comprising: constant current charging the lithium ion secondary battery with a set charging current value I 1 corresponding to a set value nC satisfying a condition represented by an expression (1): 10C<nC≦60C (1) where C is a rated capacity value of the lithium ion secondary battery, and n is a number from 2 to 60, wherein the mixed metal oxide simultaneously satisfies conditions of expressions (I) to (IV): Li x Mn y Ni z Co (1-y-z) O 2 (I) 0.85≦X≦1.1 (II) 0.1≦Y≦0.5 (III) 0.55≦Z≦0.8 (IV) where X, Y, and Z in expression (I) indicate values simultaneously satisfying the conditions of expressions (II) to (IV).