Characterization of microstructure, hydrogen storage kinetics and thermodynamics of ball-milled Mg_(90)Y_(1.5)Ce_(1.5)Ni_7 alloy

摘要

In this work, the Mg90Y1.5Ce1.5Ni7 sample is successfully prepared by combining the vacuum induction melting and the mechanical milling. The phase composition and microstructure characteristics are studied by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy measurements. The hydrogenated sample is composed of MgH2, Mg2NiH4, CeH2.73 phases, whereas only the MgH2 and Mg2NiH4 phases are decomposed during dehydrogenation. The hydrogen storage properties of Mg90Y1.5Ce1.5Ni7 samples are measured by semi-automatic Sievert type apparatus. It is found that the samples could be fully activated within three cycles of absorption and dehydrogenation, with a reversible hydrogen storage capacity of about 5.6 wt%. Also, the "optimal hydrogenation temperature" is reduced to 200 degrees C, and the dehydrogenation activation energy is calculated to be 68.2 kJ/mol and 65.8 kJ/mol by using the Arrhenius and Kissinger equations, respectively. This work provides a scientific approach to promote the practical application of Mg-based alloy. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.