Hydrogen storage properties of nanocrystalline Mg2Ni prepared from compressed 2MgH2-Ni powder

In the present work, nanocrystalline Mg2Ni with an average size of 20-50 nm was prepared via ball milling of a 2MgH(2)-Ni powder followed by compression under a pressure of 280 MPa. The phase component, microstructure, and hydrogen sorption properties were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), pressure-composition-temperature (PCT) and synchronous thermal analyses (DSC/TG). Compared to the non-compressed 2MgH(2)-Ni powder, the compressed 2MgH(2)-Ni pellet shows lower dehydrogenation temperature (290 degrees C) and a single-phase Mg2Ni is obtained after hydrogen desorption. PCT measurements show that the nanocrystalline Mg2Ni obtained from dehydrogenated 2MgH(2)-Ni pellet has a single step hydrogen absorption and desorption with fairly low absorption (-57.47 kJ/mol H-2) and desorption (61.26 kJ/mol H-2) enthalpies. It has very fast hydrogen absorption kinetics at 375 degrees C with about 3.44 wt% hydrogen absorbed in less than 5 min. The results gathered in this study show that ball milling followed by compression is an efficient method to produce Mg-based ternary hydrides. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.