PURPOSE:To enhance the cycle life characteristics by allowing the oxygen overvoltage of a positive electrode plate facing the outermost neg. electrode plate to have a lower value than the oxygen overvoltage of other pos. electrode plates, and by exposing part or the whole of that surface of the outermost neg. electrode plate which is not facing pos. electrode plate. CONSTITUTION:Either or both of the outermost part of a bunch of electrodes consist of neg. electrode plate and are formed from, for ex., three sintered Ni pos. electrode plates and three Zn sheets. A pos. electrode 1 has a low oxygen overvoltage, while another 1' has a higher oxygen overvoltage than that of the first named pos. electrode 1. In the battery jar 6, liquid retaining paper 2 faces a pos. electrode plate, while another 3 faces a neg. electrode plate. Part or the whole of that surface of the outermost neg. electrode plate which is not facing pos. electrode plate is exposed by the use of a spacer 7. Thereby central plate is substantially free from risk of overcharging, and overcharge current is consumed only on side neg. electrode plates, so that the variation in the shape is relieved both in the side plates and central plate, and decrease of charging reserve is very small.
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