Effects of Ti-V substitution on electrochemical and structural characteristics of MgNi alloy prepared by mechanical alloying

Electrochemical and structural characteristics of amorphous Mg0.9Ti0.1Ni, M g0.9V0.1Ni and Mg0.9Ti0.06V0.04Ni alloys prepared by mechanical alloying (M A) were investigated. In charge-discharge cycle tests, the decay of dischar ge capacity with increasing cycle number was suppressed by partial substitu tion with either Ti or V, and the alloy partially substituted with both Ti and V, Mg0.9Ti0.06V0.04Ni, exhibited further improved cycle performance. Re sults of X-ray diffractometry (XRD) indicated that the oxidation of Mg on t he alloy surface during the charge-discharge cycles could be fairly suppres sed by the partial substitution with both Ti and V: Moreover, it was found From Auger electron spectroscopy (AES) that thickness of oxidized surface l ayer of the MgNi alloy particle was decreased by the introduction of both T i and V. It was suggested that composite oxide layer in which both Ti and V species existed might be very effective in suppressing the oxidation of th e alloy surface, leading to the synergistic effect on charge-discharge cycl e performance. (C) 2001 Elsevier Science Ltd. All rights reserved.