Hydriding and Dehydriding Properties of Zinc Borohydride, Nickel, and Titanium-Added Magnesium Hydride

A Zn(BH₄)₂ sample was prepared by milling ZnCl₂ and NaBH₄ in a planetary ball mill under Ar gas. This sample contained NaCl. Then, 90 wt% MgH₂-5 wt% Zn(BH₄)₂-2.5 wt% Ni-2.5 wt% Ti samples [named 90MgH₂-5Zn(BH₄)₂-2.5Ni-2.5Ti] were prepared by milling in a planetary ball mill under H₂ gas. The hydrogen absorption and release properties of the prepared samples were investigated. In particular, the variations of the initial hydriding and dehydriding rates with temperature were examined. SEM micrographs and XRD patterns of 90MgH₂-5Zn(BH₄)₂-2.5Ni-2.5Ti after reactive mechanical grinding and after hydriding-dehydriding were also studied. Particle size distributions and BET specific surface areas of 90MgH₂-5Zn(BH₄)₂-2.5Ni-2.5Ti after reactive mechanical grinding and after 11 hydriding-dehydriding cycles were analyzed. The 90MgH₂-5Zn(BH₄)₂-2.5Ni-2.5Ti had an effective hydrogen storage capacity (the quantity of hydrogen absorbed for 60 min) of near 5 wt% (4.91 wt% at 593 K).