Enhanced hydrogen storage properties of a Mg-Ag alloy with solid dissolution of indium: a comparative study

A comparative study of Mg5.7In0.3Ag and Mg6Ag alloys was conducted to reveal the effects of indium (In) solid solutions on the hydrogen storage properties of Mg-based alloys. Different from the Mg6Ag alloy, the as-cast Mg5.7In0.3Ag alloy was composed of a Mg(In) solid solution and Mg3Ag. However, an initial hydrogen absorption/desorption treatment (i.e., activation) propelled the In atoms in Mg(In) toward Mg3Ag, forming (Mg, In)(3)Ag in the activated sample. This transformation involving the dissolution of In atoms from Mg into solid Mg3Ag not only greatly improved the thermodynamics of hydrogen desorption but also enhanced its catalytic effect on hydrogen desorption from additional MgH2. The (Mg, In)(3)Ag-H-2 system exhibited altered thermodynamics, as its enthalpy change of the hydrogen desorption was 62.6 kJ mol(-1) H-2. Moreover, the activation energy of the hydrogen desorption from the Mg5.7In0.3Ag sample was lowered to 78.2 kJ mol(-1).