Positive electrode active material for alkaline storage batteries

摘要

A positive electrode active material for an alkaline storage battery comprising a nickel based multi-metals oxide characterized by the ability to reversibly cycle between beta-nickel hydroxide and gamma-nickel oxihydroxide crystalline phases during electrochemical charge and discharge. Said nickel based multi-metals oxide has a large number of micropores in at least a surface layer, and an average composition of the surface layer is different from that of the interior in that at least one element selected from the group consisting of Ca, Ti, Zn, Sr, Ba, Y, Cd, Co, Cr, Bi and lanthanoids, in addition to Ni, is contained in the surface layer, or in that said at least one element is contained at a concentration higher than that of the interior. The average composition of the interior is different from that of the surface layer in that at least one element selected from the group consisting of Al, V, Mn, Fe, Cu, Ge, Zr, Nb, Mo, Ag, Sn, Sb, and W, in addition to Ni, is contained in the interior of said nickel based multi-metals oxide.