Electrochemical Properties of Co-Free Ml[sub 0.8]Mg[sub 0.2]Ni[sub 3.4]Al[sub 0.4] Hydrogen Storage Alloy Ballmilled with Ni and Mo

Abstract

In order to improve the electrochemical properties of Co-free Ml 0.8Mg0.2Ni3.4Al0.4 alloy, the alloy powder was ballmilled with Ni and Mo powders, respectively. The surface morphology and composition of the treated powder were examined by metallograph and X-ray photoelectron spectrum. The electrochemical capacity, rate dischargeability, and cycle life were investigated. It was found that the surface of the alloy powder was coated with a Ni or Mo film and the surface modification enhanced the electrochemical capacity, high-rate dischargeability, and cycle life. The Ni-coated alloy electrode had the highest electrochemical capacity of 325 mAh/g and high-rate dischargeability of 59.4%, while the Mo-coated alloy electrode exhibited the best cycle life. An electrochemical capacity of 320 mAh/g was achieved, and 85% of the initial capacity remained after 300 cycles for the Mo-coated alloy, which shows a great potential for applications for Ni-MH batteries. ©2004 The Electrochemical Society.