| abstract |
(57) [Summary] [PROBLEMS] To control the amount of residual carbon in an active material, thereby suppressing gas generation inside a battery during high-temperature storage and reducing swelling of the battery. SOLUTION: The electrode active material includes at least an electrode active material capable of inserting and extracting lithium ions, a positive electrode and a negative electrode having a binder, and a current collector, and an electrolytic solution. A lithium composite oxide represented by the following formula, wherein the amount of carbon contained in the lithium composite oxide is C / M was less than 6.0 × 10 -4 in terms of mass ratio. |