Pressure-Composition Isotherms and Cycling Properties of Mg-xFe₂O₃-yNi Alloys

In this work, Mg-x wt% Fe₂O₃-y wt% Ni alloys were prepared by mechanical grinding under hydrogen (reactive mechanical grinding) using a planetary ball mill, and pressure-composition isotherms of the samples were subsequently obtained. By measuring the absorbed hydrogen quantity as a function of number of cycles, the cycling properties of a Mg-5 wt% Fe₂O₃-15 wt% Ni alloy was investigated. The Mg-10 wt% Fe₂O₃-5 wt% Ni alloy showed an equilibrium plateau pressure of 1.92 bar at 593 K and had a hydrogen storage capacity of 5.47 wt% at 593 K. The absorbed hydrogen quantity decreased as the number of cycles increased. The Ha value varied almost linearly with the number of cycles. The maintainability of absorbed hydrogen quantity at n = 150 was 73.8% for the hydriding reaction time of 60 min.