Characteristic and analysis of high activity of Mg₂NiH₄ produced by hydriding combustion synthesis

Hydriding combustion synthesis (HCS) has been widely recognized as an innovative processing to produce magnesium based hydrogen storage alloys in recent years. In this paper, the characteristic and mechanism of the high activity of Mg₂NiH₄ produced by HCS is discussed based on the analyses of phase composition, particle characteristic and hydriding reaction by means of x-ray diffraction (XRD), scanning electron microscopy (SEM) and pressure composition temperature (PCT). It is indicated that HCS product can reach the saturated hydrogen storage capacity in the first hydriding cycle without any activation process, and the hydriding activity is higher than that of IM product at various temperatures. Pure composition, loose and porous morphology, large number of micro-fissures and small crystal grain size are the intrinsic reasons of the high activity of Mg₂NiH₄ produced by the process of HCS. These results will be helpful to control and improve the hydrogen storage properties of HCS product based on the microstructure further.