Hydrogen storage thermodynamics and dynamics of Mg–Y–Ni–Cu based alloys synthesized by melt spinning

Abstract Excessive heat stability, poor kinetics of hydrogen absorption and desorption reaction are viewed as the major setbacks for the Mg-based hydrogen storing materials application. The microstructures of samples Mg25-xYxNi9Cu (x = 0, 1, 3, 5, 7) alloys were observed by XRD, SEM, and TEM. Besides, aiming at studying the characteristics of hydrogenation/dehydrogenation, the Sievert instrument, DSC and TGA were applied in the experiments. Substituting Mg with Y can promote the formation of the second phase YNi3 but does not transform the Mg2Ni major phase. This substitution greatly prompts the amorphization. The increase of Y dosage triggers a mild decrease in the absolute values of ΔH and ΔS and remarkably boosts the improvement of dehydrogenation kinetics. Moreover, the increase in Y amount brings on a decrease in hydrogen absorption capability. The hydrogen desorption activation energy markedly lowers with increasing Y content (the E a de values of as-spun Y0 and Y3 samples are 71.38 and 66.13 kJ/mol, severally, and E k de values of them are 69.03 and 65.53 kJ/mol, respectively), which brings about the promotion of dehydrogenation kinetics of the experimental samples.