| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which is arranged to keep a high voltage as achieved when it is charged even after having been stored at a high temperature of 45°C or higher in a full-charged state, and which allows the remaining capacity to be kept high.SOLUTION: A lithium ion secondary battery comprises: a positive electrode including a positive electrode active material capable of occluding and releasing lithium ions; a negative electrode including a negative electrode active material capable of occluding and releasing lithium ions; and a nonaqueous electrolyte. The lithium secondary battery includes a sulfonyl imide compound expressed by the following general formula (1): (XSO)(FSO)NLi(where X represents a fluorine atom, an alkyl group having 1-6 carbon atoms, or a fluoroalkyl group having 1-6 carbon atoms). According to S1 s orbit's spectrum on a positive electrode surface measured by HAXPES with hard X-rays of 7.94 keV, a binding energy has a peak in a region of 2472-2476 eV. |
