Rapidly Solidified Fibers for Optimizing Hydrogen Storage Property via In Situ Multiphase Catalysts

The hydrogen de-/absorption properties of high-capacity Mg-based hydrogen storage alloys are hard to improve due to coarse α-Mg grains and catalytic element segregation. In this study, rapid solidification is introduced to Mg₉₇Ni_3-xY_x (x = 0, 0.25, 0.5, 1, at %) alloys, aiming to improve hydrogenation capacity and de-/hydrogenation kinetic jointly. The results indicate that homogeneous and refined microstructure is formed in rapid-solidified fibers, and NiY₃ and Mg₂Ni phases are generated in heat-treated fibers. Hydrogen absorption properties are improved as Y content is increased to 0.5 at %. The in situ generated YH₃ phases produce a “synergistic effect” on MgH₂ desorption and further reduce overall dehydrogenation temperature. Due to the homogeneous and refined microstructure and the ultrafine dispersed YH₂/YH₃ phases introduced by moderate Y doped, the fiber alloy can absorb more hydrogen in stage 1 and improve the hydrogenation capacity and hydrogenation rate.