Effect of element substitution and surface treatment on low temperature properties of AB3.42-type La-Y-Ni based hydrogen storage alloy

The low-temperature performance (LTP) of AB(3.42)-type La-Y-Ni hydrogen storage alloy was studied by methods of element substitution and surface treatment. The effect of Mn-additive on LTP of La1.3Ce0.5Y4.2Ni19.5-xMnxAl (x = 0, 0.2, 0.5) was systematically investigated. Electrochemical studies showed that Mn-additive deteriorated the LTP of the alloy by reducing platform pressure, deteriorating kinetic performance and forming more oxides on the alloy surface. RE-substitution and hot alkali-ultrasonic treatment of La1.3RE0.5Y4.2Ni19.5Al (RE = Ce, Sm, Nd) alloys were applied to further optimize the LTP. The maximum discharge capacity and capacity retention at the 100th cycle of La1.3Ce0.5Y4.2Ni19.5Al alloy were 252.1 mA h/g and 87.1% at 243 K, respectively. Furthermore, the LTP of RE-substitution alloys at 243 K was conspicuously improved by surface treatment, which were raised from 214.7 mA h/g to 301.1 mA h/g by Sm-substitute, from 220.9 mA h/g to 303.9 mA h/g by Nd-substitute and from 252.1 mA h/g to 254.8 mA h/g by Ce-substitute. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The low-temperature performance of AB(3.42)-type La-Y-Ni hydrogen storage alloy was studied through element substitution and surface treatment. It was found that the addition of Mn deteriorated the low-temperature performance, while rare earth substitution and surface treatment could further optimize the performance.