Electrochemical Properties of AB5 Type Flaky Hydrogen Storage Alloy Powders Prepared by Two-Stage Rapid Quenching

Abstract

AB5 type LaNi3.5Co1.1-xCrxAl0.4 (x=0, 0.1) alloy powders were prepared by two-stage rapid quenching as negative electrode materials for Ni-MH batteries. The crystal structures, morphologies and electrochemical properties were examined. The results of X-ray diffraction analysis showed that both of these alloys had a typical hexagonal CaCu5-type crystal structure. In recovered powders, a small quantity of the powders with uneven form were mixed with the flaky form powders that we have intended. The charge-discharge cyclic stability and discharge rate performance of chromium-containing LaNi3.5Co1.0Cr0.1Al0.4 alloy electrodes were much better than those of chromium-free LaNi3.5Co1.1Al0.4 alloy electrodes. Additionally, we examined the arranged packing effect of the flaky powders in the disc electrodes on the discharge rate performance. We confirmed that the performance could be improved by the arranged packing technique.