Investigations on hydrogen storage properties of LaMg8.52Ni2.23M0.15 (M=Ni, Cu, Cr) alloys

Abstract LaMg 8.52 Ni 2.23 M 0.15 (M=Ni, Cu, Cr) alloys were prepared by induction melting. X-ray diffraction showed that all the three alloys had a multiphase structure, consisting of La 2 Mg 17 , LaMg 2 Ni and Mg 2 Ni phases. Energy dispersive X-ray spectrometer results revealed that most of Cu and Cr distributed in Mg 2 Ni phase. La 2 Mg 17 and LaMg 2 Ni phases decomposed into MgH 2 , Mg 2 NiH 4 and LaH 3 phases during the hydrogenation process. Hydriding/dehydriding measurements indicated that the reversible hydrogen storage capacities of Mg 2 Ni phase in LaMg 8.52 Ni 2.23 M 0.15 (M=Cu, Cr) alloys increased to 1.05 wt.% and 0.97 wt.% from 0.79 wt.% of Mg 2 Ni phase in LaMg 8.52 Ni 2.38 alloy at 523 K. Partial substitution of Cu and Cr for Ni decreased the onset dehydrogenation temperature of the alloy hydrides and the temperature lowered by 18.20 and 5.50 K, respectively. The improvement in the dehydrogenation property of the alloys was attributed to that Cu and Cr decreased the stability of Mg 2 NiH 4 phase.