NICKEL ELECTRODE ACTIVE MATERIAL; A NICKEL ELECTRODE AND A NICKEL ALKALI STRORAGE CELL USING SUCH NICKEL ELECTRODE ACTIVE MATERIAL; AND PRODUCTION METHODS OF SUCH MATERIAL, ELECTRODE AND CELL

Fine-grained nickel electrode active material, wherein each grain contributes to electrode reaction; production method of the fine-grained nickel electrode active material; and a nickel alkali storage cell of high capacity which is excellent in over discharge characteristics. In order to produce the fine-grained nickel electrode active material, fine-grained nickel hydroxide is precipitated by adding a given amount of alkali to solution in which at least a nickel compound is dissolved while the solution is stirred. Each grain of the fine-grained nickel hydroxide is porous and 20vol% or more of the total pores volume is composed of pores of diameter 60 ANGSTROM or greater. Next, a given amount of alkali is gradually added to suspension including the fine-grained nickel hydroxide and dissolved cobalt compound so that cobalt hydroxide is precipitated on the external surface of the fine-grained nickel hydroxide. Each grain of the fine-grained nickel electrode active material comprises a nickel hydroxide and cobalt oxide having distorted crystal structure and oxidation number higher than +2. The nickel hydroxide has pores whose diameters are 60 ANGSTROM or greater. And the volume of such pores amounts to 20vol% or more of the combined volume of all of the pores.