Structures and hydrogen storage properties of Mg₉₅Ni₅ composite prepared by hydriding combustion synthesis and mechanical milling

This paper investigated the effect of the intermediate reaction, Mg+H ₂ → MgH₂ in hydriding combustion synthesis (HCS) process on the structures and hydrogen storage properties of Mg ₉₅Ni₅ prepared by HCS and subsequent mechanical milling (MM), i.e. HCS + MM. When the MgH₂ content in the HCS product was increased from 53 wt.% to 81 wt.%, the hydrogen absorption capacity of our HCS + MM product at 373 K within 100 s was increased from 0.63 wt.% to 4.90 wt.%, and the decomposition temperature onset was decreased approximately from 470 K to 450 K. The improvement in hydrogen storage properties was discussed with respect to the different structures resulted from the different HCS processes by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Moreover, the HCS product (with 81 wt.% MgH₂) milled with 3 wt.% graphite absorbed 5.56 wt.% hydrogen at 373 K in 100 s. The investigation in this study suggested that HCS combined with MM was potential in the preparation of Mg-based materials with excellent hydriding and dehydriding properties.