EFFECT OF SINTERING TIME ON PHASE STRUCTURE AND ELECTROCHEMICAL PROPERTIES OF La–Mg–Ni-BASED HYDROGEN STORAGE ALLOYS

LaNi[Formula: see text] and Mg 2 Ni intermediate alloys were used to prepare the La 4 MgNi[Formula: see text] alloy by vacuum powder sintering at 800 ∘ C, and the effects of sintering time (4, 8, and 16[Formula: see text]h) on the phase structure and electrochemical properties of La 4 MgNi[Formula: see text] hydrogen storage alloy were investigated by using XRD and electrochemical tests. The results show that the alloys consist of LaMg 2 Ni 9 phase, LaNi 5 phase, and CeNi 2 phase, and the increase of sintering time can promote the formation of the LaNi 5 phase. It is found that the alloy sintered for 16 h exhibits the best maximum discharge capacity (279.48 mAh/g), which is 48.83% higher than the capacity of the alloy sintered for 4 h. The high-rate dischargeability (HRD 900 ) increased from 43.96% (4 h) to 90.67% (16 h), which is a significant enhancement. The cycle life within 50 cycles of the alloys was higher than 70% and decreased slightly with increasing sintering time. It is concluded that the LaMg 2 Ni 9 phase with low hydrogen absorption contributes to the cycling stability of the alloy, and the significant enhancement of the high multiplicity performance is associated with an increase in the abundance of the highly catalytically active LaNi 5 phase and the surface charge transfer rate.