Effect of sintering conditions on the formation of single-phase NdMgNi4 compound and its hydrogen storage properties

Effects of different sintering conditions on the formation of single-phase NdMgNi4 compound and its electrochemical properties have been investigated. XRD analysis shows that an ideal single-phase compound of NdMgNi4 can be synthesized by sintering the pressed tablets of mixture of Mg, Ni and NdNi powders under 973 K for 5 h; single-phase compounds of REMgNi4 (RE = La, Ce, Pr) can be synthesized in this way as well. The electrochemical properties were measured by simulated battery tests. The maximum discharge capacity of NdMgNi4 compound was about 200 mAh/g, and just 78 mAh/g for CeMgNi4 compound. NdMgNi4 compound could store 3.5 H/M of hydrogen under 2.5 MPa at 298 K, whilst it is difficult to absorb hydrogen at a higher temperature (473 K).