Improved hydrogen storage properties of Ti-doped Mg95Ni5 powder produced by hydriding combustion synthesis

Ti was added to Mg-Ni alloy (Mg95Ni5) by a novel hydriding combustion synthesis (HCS) process. The effect of Ti on hydrogen absorption/desorption kinetics of Mg95Ni5 was investigated. The results showed that Ti had superior catalytic effects on hydrogen storage properties of Mg95Ni5, which required only 80 s to reach its saturated hydrogen absorption capacity of 6.29 wt% at 473 K and released 5.49 wt% hydrogen within 900 s at 553 K. Based on an Arrhenius analysis, the activation energy of the hydrogen desorption process was 80.8 kJ mol(-1) for the main phase of MgH2 in the Ti-doped Mg95Ni5. The excellent hydriding/dehydriding properties were related to the existence of TiH1.924, which improved the efficiency of mechanical milling and was helpful in the refinement of the crystallite size of MgH2, resulting in more fresh surface area and grain boundary area. Besides, it was thought to restrain the Mg particles from growth during the hydrogenation/dehydrogenation cycles.