Temperature-dependent hydrogenation behaviour and hydrogen storage thermodynamics of Mg0.9In0.1 solid solution alloy.

ABSTRACT

To clarify the hydrogen storage mechanism of Mg(In) solid solution, the hydrogenation and dehydrogenation characteristics of Mg0.9In0.1 alloy are systematically studied in this work. It is found that the Mg0.9In0.1 solid solution is first hydrogenated to Mg3In and MgH2 under a hydrogen atmosphere. The polymorphism of Mg3In leads to different hydrogenation features of the solid solution in various temperature ranges. Consequently, the reversible dehydrogenation reactions have somewhat distinct enthalpy changes due to the different crystal structures of Mg3In. When the hydrogenation temperature is not lower than 340 °C, Mg3In can be further hydrogenated to (Mg1-xInx)3In and MgH2. The hydrogenation reactions of both ß'-Mg3In and ß-Mg3In are also reversible although they have sloping hydrogenation and dehydrogenation plateaus in pressure-composition isotherms. This work provides new insights into the hydrogen storage mechanism of Mg(In) solid solution.