| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alloy composition excellent in corrosion resistance as well as in hydrogen occluding/releasing cycle life and increased in the amount of hydrogen occlusion and also to obtain an excellent electrode material for Ni-hydrogen storage battery, by adding hydroxides of heavy rare-earth elements or heavy rare-earth oxides having specified specific surface area to an LaNi5 hydrogen storage alloy in a specific proportion. SOLUTION: This alloy composition consists of (A) 100 pts.wt. of LaNi5 alloy and (B) 0.2-20 pts.wt. of at least one kind selected from the group consisting of hydroxides of heavy rare-earth elements and heavy rare-earth oxides having (0.1 to 10)m<2> /g specific surface area. It is preferable that the component (A) is represented by general formula R(Ni(w-x-y-z) Mnx Aly Coz ), where R means La or mixture of rare-each elements containing La and 4.0<=w<=6.0, 0<=x<=0.6, 0<y<=0.5, and 0<z<=1.0 are satisfied. It is preferable to regulate average grain size to 1-300μm. When the specific surface area of the oxides in the component (B) is smaller than 0.1m<2> /g, the effect of addition is hardly produced. When it exceeds 10m<2> /g, the amount of elution of the oxides into an electrolyte is increased and initial activation is extremely deteriorated and the service life of a battery is shortened.
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