Variations of the Hydriding and Dehydriding Rates of As-Milled MgH₂-Ni Alloys with Ni Content

In this work, MgH₂ was used as a starting material. Samples with compositions of 94 wt% MgH₂-6 wt% Ni, 88 wt% MgH₂-12 wt% Ni, 85 wt% MgH₂-15 wt% Ni, and 82 wt% MgH₂-18 wt% Ni were prepared by reactive mechanical grinding. The variations of the hydriding and dehydriding properties at the first hydriding-dehydriding cycle with Ni content were then investigated. MgH₂-12Ni had the highest hydriding rate and the largest quantity of hydrogen absorbed for 60 min, followed in order by MgH₂-6Ni, MgH₂-15Ni, and MgH₂-18Ni. The effects of reactive mechanical grinding were the strongest in the MgH₂-12Ni sample. As the Ni content increased from 6 wt% to 18 wt%, the percentage of the hydrogen quantity desorbed for 30 min to the theoretical capacity increased.