Properties of Mg2NiH4 prepared by microwave-assisted activation synthesis from micro-particles

The present work is devoted to working out a novel technology to prepare Mg2NiH4 and studying the properties of the samples. Comparing with the conventionally synthesized samples, it can be seen that its thermodynamic and kinetic properties and cycling life were improved. Under 3.0 MPa hydrogen pressure and within 50 s, the Mg2NiH4 prepared by microwave-assisted activation synthesis (MAAS) possesses high hydrogen storage capacity of 3.2 wt.% at 523 K. It exhibits excellent kinetic properties in the range of temperatures from 473 to 573 K and reaches 90% of the maximum capacity within 20–40 s. XRD and SEM have been used to investigate the crystal structure, morphology, and composition of the samples. It was found that, through the MAAS, the sample phase changed from original Mg and Ni to Mg2NiH4 after activation. Compared with the raw material without MAAS, the hydrogen absorption kinetics of the sample with MAAS was evidently enhanced by the activation effect of the microwave field.