Hydrogen storage kinetics and thermodynamics of Mg‐based alloys by rare earth doping and Ni substitution
2022
Bu, Wengang | Liu, Qinghai | Peng, Wenlian | Dai, Xiaodong
BACKGROUND: The traditional means of hydrogen storage cannot meet the widespread application of hydrogen energy. Therefore, developing new and efficient hydrogen storage materials and safe hydrogen storage technology is a top priority, which can effectively solve the problem of hydrogen storage and delivery. Its development and application are of great significance to environmental protection and energy development. RESULTS: Pr₅Mg₉₅₋ₓNiₓ (x = 5, 10, 15) were prepared by induction furnace melting, and the effect of Ni content on the kinetics and thermodynamics of the alloys were systematically investigated. The phase composition, microstructure and storage properties of gaseous hydrogen were investigated using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the change in Ni content significantly improves the kinetic properties of the alloys in terms of adsorption and desorption. However, it has little effect on the thermodynamic properties of the alloys. CONCLUSION: The lattice of the alloys expands after hydrogenation and shrinks after the release of hydrogen. The change of lattice stress leads to cracking or even fracture of alloy particles and, the higher the nickel content, the more cracks there are. Thus, the specific surface area of the alloys is increased and the contact area with hydrogen is expanded, promoting hydrogen diffusion within the material and improving the hydrogen absorption and desorption rate. Furthermore, as the Ni content increases, the dehydrogenation activation energy of the alloys decreases significantly, which is the main reason for the improved dehydrogenation kinetics of the alloys. © 2021 Society of Chemical Industry (SCI).
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