MgSc2 Se4 -A Magnesium Solid Ionic Conductor for All-Solid-State Mg Batteries?

Recently, the ternary spinel selenide MgSc2 Se4 was proposed to have high magnesium ion mobility and is therefore an interesting potential candidate as a solid electrolyte in magnesium secondary batteries. To test the properties of the material, a modified solid-state reaction was used to synthesize pure MgSc2 Se4 . Electrochemical characterizations identified detrimental high electronic conductivities, which limit its application as a Mg-conducting solid electrolyte. Two methods were attempted to lower electronic conductivities, including the implementation of Se-rich phases and aliovalent doping, however, with no sufficient improvement. Based on the mixed conducting properties of MgSc2 Se4 , a reversible insertion/extraction of Mg2+ into the spinel structure could be demonstrated.