Role of NiMn9.3Al4.0Co14.1Fe3.6 alloy on dehydrogenation kinetics of MgH2

Abstract

Hydriding and dehydriding properties of MgH2 - x wt. % NiMn9.3Al4.0Co14.1Fe3.6 (x = 10, 25, 50) nanocomposites have been investigated in present work. Doped alloy was prepared by arc melting method and ball milled with MgH2 to get nanocomposites. Onset temperature as low as 180 °C was observed for MgH2-50 wt% system which is 80 °C lower than the as-milled MgH2 giving 131.34 KJ/mol activation energy. Structural analysis shows tetragonal, orthorhombic and monoclinic phases for MgH2, Al60Mn11Ni4 and Mg2NiH4. Morphology by SEM were undertaken to investigate the effect of hydrogenation on nanostructured alloy. DSC studies show a single broad exothermic peak in the temperature range 48 °C–353 °C after alloy addition in MgH2. These results indicate that the hydrogenation properties of MgH2 nanocomposite have been improved compared to the as-milled MgH2. Keywords: Hydrogen storage, Activation energy, Mg based nanocomposites, Phase structure, TGA