Nickel hydroxide positive electrode active material having a surface layer containing a solid solution nickel hydroxide with manganese incorporated therein

摘要

A positive electrode active material and a positive electrode for an alkaline storage battery are disclosed which exhibit high charge efficiency at a high temperature. The positive electrode active material comprises particles formed by agglomeration of crystals of nickel hydroxide active material, at least the surface layer of the particles containing a solid solution nickel hydroxide with manganese incorporated therein. The solid solution is present as crystals growing on the crystal surface of said nickel hydroxide active material and/or crystals independent of crystals of the nickel hydroxide active material. The content of manganese in the solid solution is at least one mole percent on the whole metal ions in the solid solution and not higher than 10 mole percent on the combined total amount of the metal ions in the nickel hydroxide active material and the solid solution. The positive electrode for an alkaline storage battery contains the above-mentioned active material and a compound of at least one element selected from the group consisting of Ca, Sr, Ba, Cu, Ag, Cd, Y and Yb.