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

LaSm0.4Y1.6Ni10.5Mn0.4Al0.2 hydrogen storage alloy with a Ce2Ni7-type single-phase has been prepared and its electrochemical properties and hydrogen storage properties are system-atically 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 cor-responding 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.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A LaSm0.4Y1.6Ni10.5Mn0.4Al0.2 hydrogen storage alloy with a Ce2Ni7-type single-phase was prepared and its electrochemical and hydrogen storage properties were investigated. The alloy exhibited promising electrochemical properties, with maximum capacities of 385.8 mAh/g at 0.2C, 356.8 mAh/g at 1C, and a cycling stability of 86.72% at 100 cycles. The hydrogen storage capacity of the alloy was primarily determined by the charge transfer rate, with a capacity of 272.7 mAh/g at 1500 mA/g. The alloy showed irreversible losses in hydrogen storage due to discordant lattice expansion rates of the [A2B4] and [AB5] subunits during absorption/desorption.