| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery excellent in output characteristics and less decrease in output even after repeating charge and discharge.SOLUTION: A lithium ion secondary battery 100 provided by the present invention comprises: a positive electrode 30; a negative electrode 40; and a nonaqueous electrolyte 90. The positive electrode 30 includes lithium transition metal oxide having a layered structure, as a positive electrode active material. The positive electrode active material contains a metal element Mof at least one selected from among Ni, Co and Mn, and further contains W. In the battery 100, the nonaqueous electrolyte 90 having a composition containing at least one of a difluorophosphate and a monofluorophosphate is used. |
