Preparation and hydrogen storage properties of single-phase Ce2Ni7-type La–Sm–Y–Ni based hydrogen storage alloy

摘要

? 2022 Hydrogen Energy Publications LLCLaSm0.4Y1.6Ni10.5Mn0.4Al0.2 hydrogen storage alloy with a Ce2Ni7-type single-phase has been prepared and its electrochemical properties and hydrogen storage properties are systematically investigated. The crystal structure of the alloy transformed completely into the Ce2Ni7-type single-phase via annealing at 1323 K for 16 h. The Ce2Ni7-type single-phase alloy has promising electrochemical properties, including 0.2Cmax = 385.8 mAh/g, 1Cmax = 356.8 mAh/g, and S100 = 86.72. The HRD of the Ce2Ni7-type single-phase alloy is primarily determined by the charge transfer rate, which is HRD1500 = 75.75 and the corresponding electrochemical capacity at 1500 mA/g is 272.7 mAh/g. The PCT curves of the alloy present double pressure platforms owing to the hydrogen atoms occupying the A2B4 subunit preferentially and entering the AB5 subunit subsequently. Similarly, because the lattice expansion rates of the A2B4 and AB5 subunits vary discordantly throughout hydrogen absorption/desorption, the hydrogen storage capacity of the alloy experiences irreversible losses.