Computational Investigation of Chalcogenide Spinel Conductors for All-Solid-State Mg Batteries

We report seven new MgLn 2 X 4 (Ln = lanthanoid, X = S, Se) spinels that have low barriers for Mg migration (<380 meV) and are stable or nearly stable (within 50 meV/atom of stability with respect to competing structures and compositions) as calculated with density functional theory. As the size of the Ln increases, Mg mobility is found to increase, but stability in the spinel structure is found to decrease.