Enhancement of hydrogen storage properties from amorphous Mg85Ni5Y10 alloy

Abstract

Amorphous precursors have been successfully used in the preparation of Mg-based hydrogen storage materials. Unfortunately, the improvement and the underlying mechanisms of hydrogen storage kinetics of these materials are far from being fully understood. Herein, the hydrogen storage properties of amorphous and crystalline Mg85Ni5Y10 (at%) alloys prepared by melt-spinning and induction-melting, respectively, were comparatively studied. The results indicate that the hydrogen storage capacity and hydrogen release/uptake kinetics of the melt-spun alloy are much higher and faster than that of the induction-melted alloy. The reversible storage capacity of 4.2 wt% H2 for the activated melt-spun Mg85Ni5Y10 alloy is much higher than 3.8 wt% for the induction-melted sample at 200 °C. Moreover, the melt-spun alloy could release 4.1 wt% within 30 min at temperatures above 275 °C, which is close to its theoretical hydrogen storage capacity of 4.2 wt%, while the induction-melted alloy could only release 3.5 wt% H2 under the same conditions. Multiple cracks formed during the activation cycles together with a uniform distribution of catalytic YH2/YH3 and Mg2Ni/Mg2NiH4 particles are thought to be responsible for the excellent hydrogen storage kinetics of the melt-spun alloy. This work provides guidance for further designing and developing high-performance and non-crystalline Mg-based hydrogen storage materials.