Patent ID: 6942947

Claim:
Hydrogen storage alloy comprising: (1) a main alloy composition expressed by the formula of Mm−(Ni−Al−Co−Mn−Cu); (2) a ratio of the number of atoms expressed by the formula of Ni−Al−Co−Mn−Cu) is exhibited by 5.5<(Ni+Al+Co+Mn)≦7.0, and 4.0≦Ni, when Mm is set at 1 in a ratio of the number of atoms; and (3) an internal structure having a hydrogen storage alloy phase expressed by the general formula of AB 5 , and a second phase existing in said hydrogen storage alloy phase, wherein said whole composition is expressed by the formula of MmNi (3.95+p) Al (0.3+q) Co (0.4+r) Mn (0.45+s) Cu (0.10+t) , and 0.3<(p+q+r+s+t)≦1.8.