Structure and Electrochemical Hydrogen Storage Properties of Mg-Ti Based Materials Prepared by Mechanical Alloying

Abstract

High energy ball milling was used to prepare Mg100-xTix -10 wt.% Pd compounds, with x ranging from 20 to 80. X-ray diffraction analyses combined with Rietveld refinement shows that the as-milled compounds are made of a mixture of hcp and bcc phases in various proportions depending on the Mg/Ti ratio in the initial mixture. The electrochemical hydrogen absorption capacities of these compounds were assessed in KOH electrolyte. The number of activation cycles and the maximum discharge capacity value are strongly dependant on the material composition. The highest hydrogen discharge capacity (475 mAh g-1) is obtained with Mg50Ti50-10 wt.% Pd compound. Upon hydrogenation, the crystalline structure of the compound evolves into an fcc phase with a lattice parameter of 4.40 Aå.