Negative electrode active material for nickel-metal hydride battery and nickel-metal hydride battery using the same, and method for treating negative electrode active material for nickel-metal hydride battery

摘要

A negative electrode active material for a nickel-metal hydride battery of the present invention includes a hydrogen storage alloy, the hydrogen storage alloy containing La, Mg, Ni, Co, Al, and element M. The molar ratio y of Ni to the total of La and Mg is 2≦y≦3, the molar ratio z of Co to the total of La and Mg is 0.25≦z≦0.75, the molar ratio α of Al to the total of La and Mg is 0.01≦α≦0.05, and the molar ratio x of Mg to the total of La and Mg is 0.01≦x≦0.5. Element M represents at least one selected from the group consisting of Y and Sn, and the content of element M in the hydrogen storage alloy is 0.4 wt % or less.