| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of ensuring adequate security by suppressing thermorunaway of a battery due to overcharge, even when the charging current or charging voltage changes.SOLUTION: In a lithium ion secondary battery 22 having an electrode group 21 in which a positive electrode 1 and a negative electrode 2 are arranged with separators 3, 4 being interposed therebetween, a battery can 11 housing the electrode group 21, and a nonaqueous electrolyte injected into the battery can 11, the ratio of the weight A of a positive electrode active material contained in the positive electrode and the weight B of a negative electrode active material contained in the negative electrode satisfies a relation 1.90≥A/B≥1.50, and 2.8-3.2 wt% of cyclohexylbenzene is added to the nonaqueous electrolyte. With such an arrangement, adequate security can be ensured during overcharge even if the charging current changes. |
