STUDY ON PHASE STRUCTURE AND ELECTROCHEMICAL PROPERTIES OF La–Mg–Ni-BASED HYDROGEN STORAGE ALLOY BY HIGH-TEMPERATURE SINTERING

Starting from two precursors, LaNi 3 and MgNi 2 , La[Formula: see text]Mg[Formula: see text]Ni[Formula: see text] alloys were prepared by vacuum powder sintering at the temperatures of [Formula: see text]C, [Formula: see text]C, and [Formula: see text]C. To improve the overall electrochemical properties of the alloy, excessive Mg was added to the alloy at [Formula: see text]C. XRD analysis results show that the alloys consist of LaNi 5 phase, Ce 2 Ni 7 -type phase, and Ce 5 Co[Formula: see text]-type phase. The increase in temperature can promote the formation of the LaNi 5 phase and gradually make the Ce 2 Ni 7 -type phase fade away. Adding excessive Mg makes the Ce 2 Ni 7 -type phase increase significantly. The electrochemical studies showed that the alloy sintered at [Formula: see text]C has a maximum discharge capacity of 209.8[Formula: see text]mAh/g and the best high-rate discharge ability at 900[Formula: see text]mA/g ([Formula: see text]). However, their cycling stabilities showed the opposite results. In addition, the addition of Mg also greatly enhanced the cycling stability of the alloy from 32% to 61.3%. It can be found that the cycling stability is affected by both phase composition and lattice stress.