| 摘要 |
A nickel-metal hydride secondary cell (2) holds therein an electrode group (22) and an alkaline electrolyte solution containing NaOH as a main constituent of its solute. The electrode group has a positive electrode (24) and a negative electrode (26) lapped one over the other with a separator (28) therebetween. The negative electrode (26) contains a hydrogen absorbing alloy having a composition represented by the general formula: (RE 1-x T x ) 1-y Mg y Ni z-a Al a (where RE is at least one element selected from among Y, Sc and rare-earth elements, T is at least one element selected from among Zr, V and Ca, and subscripts x, y, z and a are values respectively satisfying 0 ‰¤ x, 0.05 ‰¤ y ‰¤ 0.35, 2.8 ‰¤ z ‰¤ 3.9, and 0.10 ‰¤ a ‰¤ 0.25), the hydrogen absorbing alloy has a crystal structure in which an AB 2 subunit and an AB 5 subunit are superimposed one upon the other, and Cr is substituted for part of the Ni. |
