Influence of adding graphene on the hydrogen storage thermodynamics and kinetics of as-milled CeMg12–Ni alloy

Abstract

Graphene can been used to improve the hydrogen storage performance of magnesium based materials because of its outstanding electrical conductivity, high specific surface area, and good mechanical qualities. In this paper, mechanical ball milling method was utilized to prepare the CeMg12/Ni alloy combined with graphene in order to investigate the impact of graphene on microstructure, kinetics, and thermodynamic properties of alloy. The results reveal that the addition of graphene can refine the grains of alloy, increase the surface defects of alloy particles and promote Ni to be dissolved in the main phase of the alloy. The absolute value of enthalpy drops from 65.27 kJ/mol to 60.3 kJ/mol when Graphene is added at a higher concentration. The addition of graphene improves the dehydrogenation performance of alloy hydride by lowering its thermal stability. Because of a minimum dehydrogenation activation energy of 85.23 kJ/mol and dehydrogenation characteristic time of 1090s, the alloy with 6 wt% Graphene exhibits the best dehydrogenation kinetic performances.