Hydrogen sorption kinetics of magnesium hydride enhanced by the addition of Zr8Ni21 alloy

Abstract

Hydrogen absorption and desorption kinetics, and thermodynamics of MgH 2 ball milled with addition of the Zr 8Ni 21 alloy have been studied. Different additive amounts were used from 3 to 12.5 wt%. The highest reversible capacity of 6.5 wt% of hydrogen was found for the samples with 3 and 5 wt% of additive. The best reaction kinetics was found with 10 wt% of additive: 5.9 wt% H 2 was desorbed in 4 min at 300 °C and 0.1 bar of hydrogen pressure. Regardless of the different storage capacities, all the samples were almost fully hydrided in 1 min using a hydrogen pressure of 10 bar at 250 and 300 °C. The enthalpy of formation of magnesium hydride was not affected by the presence of the additive.