LAUSR

Abstract The influence of substitution of R (R = Nd, Gd and Er) for Ca on hydrogen storage performances of Ca2MgNi9 compound was investigated. RCaMgNi9 compounds have obvious hydrogen absorption and desorption plateaus though their hydrogen storage capacities are reduced with the decrease of atomic radii of R. The hydriding enthalpies of RCaMgNi9 (R = Nd, Gd and Er) range from −30.4 to −19.5 kJ mol−1 H2 as the change of cell volumes. Moreover, RCaMgNi9 alloy electrodes show better cycle stabilities and high-rate discharge capacities than Ca2MgNi9. However, GdCaMgNi9 and ErCaMgNi9 have relatively worse hydrogen storage properties as compared to NdCaMgNi9 due to the small atomic radii of Gd and Er.