| 摘要 |
PROBLEM TO BE SOLVED: To increase the service capacity of a battery and reduce the increase of the internal pressure of the battery by combining a hydrogen storage alloy electrode having the capacity at the negative electrode charging depth of a specific % or below with an unsintered nickel positive electrode. SOLUTION: A coated layer of a coating Ni active material is alkali heat- treated to convert cobalt into a higher order. When a nickel positive electrode filled with this coating Ni active material is used, the nonreactive capacity ratio of the nickel positive electrode is reduced, and the electrode capacity is increased. In the theoretical capacity of the positive electrode which is the total of the nickel hydroxide uncharged/undischarged capacity (a), battery service capacity (b), and nickel hydroxide undischarged capacity (c), (a) and (c) can be decreased, and (b) can be increased. When the negative electrode charging depth expressed by the formula is regulated to 80% or below, the negative electrode marginal capacity is sufficiently secured, the reduction of the cycle characteristic caused by the operation of a safety valve can be prevented, and a battery having a high capacity and an excellent cycle life is obtained. |
