Improvement in the Hydrogen-Storage Characteristics of Magnesium Hydride by Grinding with Sodium Alanate and Transition Metals in a Hydrogen Atmosphere

摘要

In this work, MgH2 was used as a starting material instead of Mg. The sample was prepared by grinding MgH2 with sodium alanate and transition metals in a hydrogen atmosphere. Its hydriding and dehydriding properties were measured followed by X-ray diffraction (XRD) analyses and observations of its microstructure. Activation was not required for the 86MgH(2) + 10Ni + 2NaAlH(4) + 2Ti sample. At the first cycle (n = 1), the sample absorbed 4.96, 5.28 and 5.36 wt% H for 10, 15 and 60 min, respectively, at 593 K in 12 bar H-2, showing that the sample absorbed quite a large amount of hydrogen for 60 min (nearly 5.5 wt% H). The initial hydriding rate increased as the temperature increased from 423 K to 553 K and decreased from 553 K to 593 K. The sample showed quite high hydriding rates at relatively low temperatures 423 K (at n = 1) and 473 K (at n = 2) in 12 bar H-2, compared with those of other metallic element(s) or compound(s)-added Mg or MgH2 alloys, absorbing 2.89 wt% H for 5 min, 2.97 wt% H for 10 min, and 3.31 wt% H for 60 min at 473 K.