Method of producing a hydrogen storage alloy for alkaline storage battery

摘要

The present invention provides a method of producing a hydrogen storage alloy low in cobalt content which can restrains a decrease in cycle life characteristic and preservation characteristic of an alkaline storage battery when the alloy is used as a negative electrode. The method includes the following steps. An Mm-Ni system hydrogen storage alloy which has a crystal structure of CaCu5 and contains 15 atom% or less of cobalt is powdered to have an average particle diameter of 10-100 mu m. Then, the powdered alloy is immersed in a treatment solution at 80-130 DEG C, the treatment solution comprising an alkaline aqueous solution containing 10 g/l or more of lithium hydroxide and having a specific gravity of 1.1 or higher, and cobalt ions which is contained in the alkaline aqueous solution, thereby forming a layer containing nickel and cobalt in higher concentration than in the bulk of the powdered alloy onto the alloy surface.