Highly improved hydrogen storage dynamics of nanocrystalline and amorphous NdMg₁₂-type alloys by mechanical milling

To improve the hydrogenation and dehydrogenation dynamics of NdMg₁₂-type alloy, we replaced part of Mg with Ni in the samples and used the ball milling method to prepare NdMg₁₁Ni + x wt.% Ni (x = 100, 200) samples. The influences of milling duration and Ni content on the electrochemical and gaseous dynamics of the samples were studied in detail. Dehydrogenation activation energies of samples were calculated by using Kissinger and Arrhenius methods. The conclusions show that the dynamic properties of samples are significantly enhanced with the increase in Ni content. With the change of the milling duration, the gaseous hydrogenation rate and high rate discharging capability reach the maximal values. However, the dehydrogenation dynamics of sample alloys are always enhanced with the prolonging of milling duration. More concretely, prolonging milling duration from 5 to 60 h improves the dehydrogenation ratio of NdMg₁₁Ni + 100 wt.% Ni alloy from 58.03% to 64.81% and that of NdMg₁₁Ni + 200 wt.% Ni alloy from 62.20% to 71.59%. Besides, the enhancement of gaseous hydrogen storage dynamics of the samples is believed to be the result of the declined dehydrogenation activation energy resulted from the increase in milling duration and Ni content.