| 摘要 |
A lithium ion secondary battery which includes: a power generation element including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte; a case accommodating the power generation element and having an opening; and a sealing plate sealing the opening of the case is charged. The sealing plate has an external terminal of the positive or negative electrode, and an internal terminal electrically connected to the positive or negative electrode. The external and internal terminals are connected to each other and have an electrical resistance therebetween of 0.1 to 2 mOmega. Two or more constant-current charging steps in each of which the secondary battery is charged at a constant charge current until a charge voltage reaches an end-of-charge voltage are performed. In the two or more constant-current charging steps, the secondary battery is subjected to constant-current charging at a current Ic(1) of 1 to 5 C until the charge voltage reaches a target voltage Ecs(1). After the charge voltage reached the target voltage Ecs(1), the secondary battery is subjected to constant-current charging at a current Ic(k) satisfying Ic(k)<Ic(1) until the charge voltage reaches a target voltage Ecs(k) higher than the target voltage Ecs(1). |
