SURFACE TREATMENT METHOD OF HYDROGEN STORAGE ALLOY BY STEAM AND ALLOY OBTAINED THEREBY

摘要

PROBLEM TO BE SOLVED: To provide a surface activating method for a hydrogen storage alloy without requiring wastewater treatment by eliminating an inactive layer from the surface of the hydrogen storage alloy and forming a metal-rich activated layer. SOLUTION: This is a method to activate the surface of a hydrogen storage alloy by bringing steam into contact with the hydrogen storage alloy and causing surface reaction in a temperature range higher than 200 deg.C and lower than 400 deg.C. A range from 200 deg.C to 400 deg.C is selected as the temperature range in which steam should contacts with the hydrogen storage alloy. Consequently, contact decomposition of water on Mm metals, e.g. La, Mn, and Al is caused to convert these metals into hydroxides and at the same time Ni compounds are reduced by generated hydrogen to produce Ni alloy having catalytic activity. Another gas as a carrier and a diluting gas may be mixed with steam. The method is especially suitable for activation treatment of a hydrogen storage alloy for an anode active material for a battery.