Positive electrode active material for alkaline storage batteries, and positive electrode and alkaline storage battery using the same

A positive electrode for an alkaline storage battery comprising an active material comprising a nickel hydroxide powder,

• wherein said nickel hydroxide is a solid solution containing magnesium,
• a magnesium content in said nickel hydroxide is 2 to 7 mol % of all metallic elements contained in said nickel hydroxide,
• a tap density of said nickel hydroxide is 1.9 g/cm3 or more,
• a half-width of a peak attributed to (101) face near 2θ=37 to 40° in a powder X-ray diffraction pattern of said nickel hydroxide by CuK α radiation is 0.7 to 1.2°,
• a ratio of intensity B of a peak in said powder X-ray diffraction pattern attributed to (001) face near 2θ=18 to 21° to intensity A of said peak attributed to (101) face near 2θ=37 to 40°:
• B/A is 1.1 or more, and
• a sulfate ion content in said nickel hydroxide is 0.5 wt % or less;
• further containing 0.5 to 3 parts by weight of a powder comprising an oxide of at least one element selected from the group consisting of Y, Yb, Lu, Ti and Ca per 100 parts by weight of said active material.