| 摘要 |
Disclosed is a lithium ion secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolytic solution. The positive electrode contains a lithium-(transition metal) composite oxide having a layered structure as a positive electrode active material. The positive electrode active material contains at least one metal element (M0) selected from Ni, Co and Mn, additionally contains at least one metal element (M') selected from Zr, Nb and Al, and additionally contains W. When 2 g of a powder of the positive electrode active material and 100 g of pure water are agitated together to prepare a suspension and the suspension is filtered to prepare a filtrate, the amount of W eluted into the filtrate is 0.025 mmol or less per 1 g of the filtrate as measured by inductively coupled plasma mass spectrometry. |
