To heighten heat resisting characteristics and liquid keeping characteristic so as to secure the cell characteristic over a long period of time and to lengthen the service life by interposing a separator impregnated with an electrolytic solution between both electrodes of a cell, formed by coupling an organic fiber and an inorganic fiber organically.

A separator 20 interposed between a nickel pole 10 and a hydrogen pole 11 is formed by organic woven or non-woven fabric of an organic fiber of polyamide resin such as nylon, and polypropylene or the like and at least one kind of inorganic fiber such as zirconia, asbestos, and yttria and the like. Thus, the separator 20 has both heat resisting characteristic which is the characteristic of an inorganic fiber and good liquid keeping characteristic which is the characteristic of an organic fiber, so that it is possible to prevent lowering of cell capacity due to shortage of an electrolytic solution caused by repetition of charging and discharging. Heat resisting characteristic is improved to secure high-accuracy cell performance over a long period of time.