Characterization of hydrogen storage properties of Mg-30Â wt.% Ti1.0V1.1Mn0.9 composite

Mg-30 wt.% Ti1.0V1.1Mn0.9 hydrogen storage composites were prepared by reactive ball milling (RBM) of a mixture of Mg and Ti1.0V1.1Mn0.9 alloy powders in hydrogen atmosphere. It was determined by X-ray diffraction (XRD) analysis that Mg partly transformed into MgH2 owing to the in situ activation under RBM process. The microstructures of the composites obtained by scanning electronic microscopy (SEM) analysis showed that Mg and Ti1.0V1.1Mn0.9 particles were greatly refined after ball milling and the smaller Ti1.0V1.1Mn0.9 particles were dispersed uniformly on the surface of Mg particles. Among the samples, the Mg-30 wt.% Ti1.0V1.1Mn0.9 composite milled for 20 h at a rotation speed of 200 rpm had the best hydrogen storage properties, both in hydrogen storage capacity and hydriding/dehydriding reaction rate. It absorbed 4.46 wt.% hydrogen at 606 K under the atmosphere of 3 MPa H2 within an hour for the first cycle. Even at 377 K, it still absorbed 1.77 wt.% hydrogen within an hour. No obvious degradation in hydrogen absorption/desorption property was observed for this sample after three hydriding/dehydriding cycles at 606 K. The improved hydriding/dehydriding properties of the composites were discussed with respect to the catalytic effect of Ti1.0V1.1Mn0.9 particles.