Effect of Sm on the cyclic stability of La-Y-Ni-based alloys and their comparison with RE-Mg-Ni-based hydrogen storage alloy

The LaY2Ni9.7Mn0.5Al0.3 and LaSm0.3Y1.7Ni9.7Mn0.5Al0.3 alloys have been synthesized to investigate the effect of Sm partial substitution for Y on the cyclic stability of A(2)B(7)-type La -Y-Ni-based alloys. Their cyclic properties were also compared with the A(2)B(7)-type (RE0.85Mg0.15)(2)(NiAl)(7) (RE = Rare Earth) alloys. The gas-solid and electrochemical cycle lives were tested. The structural stability, pulverization, and oxidation/corrosion performances were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical methods. The partial substitution of Sm for Y improves anti-corrosion and anti-pulverization performances, thereby increasing the cycle life of A(2)B(7)-type La-Y-Ni-based hydrogen storage alloys. The A(2)B(7)-type RE-Y-Ni-based alloys exhibit better crystal structure stability, but the gas-solid and electrochemical cyclic stability is worse than A(2)B(7)type (RE0.85Mg0.15)(2)(NiAl)(7) alloys due to easier pulverization of particles and the oxidation of Y elements. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.