Investigations on hydrogen storage properties of Mg2Ni +x wt% LaMg2Ni (x=0, 10, 20, 30) composites

Mg2Ni+x wt% LaMg2Ni (x=0, 10, 20, 30) composites have been prepared by ball milling Mg2Ni and LaMg2Ni hydrides. X-ray Diffraction indicates that the composites consist of LaH3 and Mg2NiH4 phases. Mg2NiH4 phase transforms between with Mg2Ni phase during hydriding/dehydriding cycling, while the LaH3 phase exists still after dehydriding process. Backscatter Electron results reveal that the LaH3 phase, which is decomposed from hydrided LaMg2Ni, distributes in Mg2Ni alloy homogeneously after ball milling procedure. Hydriding/Dehydriding measurements indicate significant improvement in reversible hydrogen storage properties of the composites over Mg2Ni at low temperature. At 473 K, the hydrogen storage capacity of Mg2Ni+20 wt% LaMg2Ni composite reaches 3.22 wt% and can reversely desorb hydrogen completely, while the pure Mg2Ni hydride is hardly desorbs hydrogen at this temperature. The improvement in the hydrogen storage properties is attributed to the existence of LaH3 phase in the composites.