Ether Molecule Decomposition on MgM₂O₄ (M = Mn, Fe, Co) Spinel Surface: A First-principles Study (Supporting Information)

The transition between MgM₂O₄ (M = Mn, Fe, Co) spinels (SPs) and MgMO₂ rock salts (RS) has attracted considerable interest for cathode reactions in future magnesium battery applications. To improve the cycling performance, one should suppress the consumption of solvent molecules. In this study, we investigated ether solvent decomposition on MgM₂O₄ SP and MgMO₂ rock-salt surfaces using first-principles calculations. We found that the C–H bond dissociation of ether molecules on the SP surface was exothermic, while the C–H bond dissociation on RS and C–O bond dissociation on both SP and RS surfaces were endothermic, irrespective of the transition metal element. The products of C–H dissociation reactions at the SP surfaces have occupied states originating from SP surfaces inside the bandgap. As the SP surface is destabilized by C–H dissociation, the electrons at this level can be extracted as an oxidative current.