Gaseous hydrogen storage properties of Mg-Y-Ni-Cu alloys prepared by melt spinning

Abstract

For purpose of promoting the hydrogen absorption and desorption thermodynamics and kinetics properties of MgNi-based alloys, partially substituting Y and Cu for Mg and Ni respectively and melt spinning technique were applied for getting Mg25–xYxNi9Cu (x = 0–7) alloys. Their microstructures and phases were characterized with the help of X-ray diffraction and transmission electron microscopy. Their hydrogen absorbing and desorbing properties were tested by a Sievert apparatus, DSC, and TGA, which were connected with a H2 detector. In order to estimate the dehydrogenation activation energy of alloy hydride, both Arrhenius and Kissinger methods were applied for calculation. It is found that their hydriding kinetics notably declines, however, their hydrogen desorption kinetics conspicuously improves, with spinning rate and Y content increasing. Their hydrogen desorption activation energy markedly decreases under the same constraint, and it is found that melt spinning and Y substituting Mg improve the real driving force for dehydrogenation. As for the tendency of hydrogen absorption capacity, it presents an elevation firstly and soon after a decline with the rising of spinning rate, however, it always lowers with Y content growing. With Y content and spinning rate increasing, their thermodynamic parameters (ΔH and ΔS absolute values) visibly decrease, and the starting hydrogen desorption temperatures of alloy hydrides obviously lower.