Synergistic hydrogen desorption properties of the 4LiAlH4Â +Â Mg2NiH4 composite

Mg2NiH4 was prepared by hydriding combustion synthesis (HCS) method firstly. Then, the as prepared Mg2NiH4 was mechanically milled with LiAlH4 to form a novel composite of 4LiAlH4 + Mg2NiH4. Hydrogen storage properties and reaction mechanism of the 4LiAlH4 + Mg2NiH4 composite during hydrogenation/dehydrogenation have been investigated systematically by pressure-composition-temperature (PCT), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements. The microstructure of the composite has been investigated by scanning electron microscopy (SEM). The experimental results show that there is a mutual destabilization effect between Mg2NiH4 and LiAlH4 during hydrogen desorption. Mg2NiH4 can promote the decomposition of LiAlH4 in both of the ball milling process and the thermal desorption process. Conversely, the in situ formed Al from the decomposition of LiAlH4 can destabilize Mg2NiH4 via a new reaction pathway with lower activation energy. Moreover, the 4LiAlH4 + Mg2NiH4 composite shows ultrafast re-hydrogenation kinetics, and the re-hydrogenation mechanism has been revealed.