Hydrogen storage in MgH2[sbnd]LaNi5 composites prepared by cold rolling under inert atmosphere

Abstract

Mg-AB5 composites are promising systems for hydrogen storage applications, due to their possibility of hydrogen cycling at relatively low temperatures. Traditionally, these composites are mainly processed by high-energy ball milling (HEBM) techniques employing longer processing times. In this study, cold rolling was applied to prepare MgH2LaNi5 composites and the hydrogen storage properties were investigated. The materials were processed using a vertical rolling mill under argon atmosphere, leading to a good homogeneity and no contamination at shorter processing times. The mixture of MgH2-1.50 mol.% LaNi5 showed the best hydrogen storage properties at 200 °C and 100 °C and the lowest desorption temperature even when compared to cold rolled MgH2. The results indicate that the composite MgH2LaNi5 is transformed into a mixture of three phases MgH2, Mg2NiH4 and LaH3 upon hydrogen absorption/desorption cycles. The synergetic effect among these phases when in appropriate proportion in the sample seems to play a crucial role in the acceleration of hydrogen absorption/desorption kinetics at lower temperatures in comparison to MgH2.