Characterization of Hydrogen-Storage Properties and Physical Properties of Zinc Borohydride and Transition Metals-Added Magnesium Hydride

Abstract

In this work, 90 wt.% MgH₂ + 5 wt.% Ni + 1.7 wt.% Zn(BH₄)₂ + 1.7 wt.% Ti + 1.7 wt.% Fe samples (named 90MgH₂ + 5Ni + 1.7Zn(BH₄)₂ + 1.7Ti + 1.7Fe) were prepared by milling in a planetary ball mill in a hydrogen atmosphere. The fraction of additives was small (10 wt.%) in order to increase hydriding and dehydriding rates without decreasing the hydrogen storage capacity much. The hydrogen absorption and release properties of the prepared samples were investigated. 90MgH₂ + 5Ni + 1.7Zn(BH₄)₂ + 1.7Ti + 1.7Fe had an effective hydrogen storage capacity of 5 wt.%. The activation of 90MgH₂ + 5Ni + 1.7Zn(BH₄)₂ + 1.7Ti + 1.7Fe was completed after 2 hydriding-dehydriding cycles. At n = 3, the sample absorbed 4.14 wt.% H for 5 min and 5.00 wt.% H for 60 min at 593 K under 12 bar H₂. The sample dehydrided at the 3rd hydriding-dehydriding cycle contained Mg and small amounts of β-MgH₂, MgO, Mg₂Ni, TiH_1.924, and Fe. The BET specific surface areas of the sample after milling in a hydrogen atmosphere and after 3 hydriding-dehydriding cycles were 57.9 and 53.2 m²/g, respectively.

DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14878