Precipitation of abundant nano-interfaces in Sc/In-doped Mg-Y-Zn alloy and the two-stage hydrogenation behavior: Enabling rapid reaction kinetics

Mg-Y-Zn hydrogen storage alloy has the advantages of high capacity and good oxidation resistance. To weaken the “blocking effect” of bulk MgH₂ for rapid hydrogen absorption and desorption, a novel Mg₉₅Y₂Sc₁Zn₁In₁ alloy with α-Mg phase, eutectic phase, and slight LPSO structure is designed. Its hydrogenation capacity is 5.97 wt.% at 350°C with dehydrogenation activation energy of 136.77 kJ·mol⁻¹. With further annealing, abundant interfaces of nanophases are constructed, and an elevated hydrogenation capacity of 6.39 wt.% is reached with dehydrogenation activation energy reducing to 128.46 kJ·mol⁻¹. The abundant nano-interfaces in α-Mg phase provide fast diffusion paths for H atoms and the hydrogenation process in the interior of particle is accelerated. Consequently, the increased hydrogenation capacity is resulted from rapid hydrogen absorption in Stage 1. Moreover, the nano-interfaces of multiphase are beneficial to the two-dimensional migration of Mg/MgH₂ interfaces, indicating extra energy is provided to accelerate the desorption of MgH₂.