Effect of advanced alkaline treatment on the electrochemical characteristics of hydrogen storage alloys

An advanced technique is studied for the formation of a composite surface l ayer of the powder of hydrogen storage alloys, in which metallic Cu is dist ributed in the rare-earth hydroxide layer. An alkaline solution which conta ins a Cu salt (CuSO4), reductive agent and stabilizing agent for stabilizin g Cu2+ was developed to implant metallic Cu in the surface layer. Through t he surface analyses using EDS and AES and testing of the electrochemical pr operties, it has been found that it is possible to synthesize a composite s urface layer in which Cu is implanted in the rare-earth hydroxide layer. Th is is effective for activity enhancement and for improving the high rate di scharging capability of metal hydride electrodes. (C) 1999 Published by Els evier Science S.A. All rights reserved.