Glyme Solvent Decomposition on Spinel Cathode Surface in Magnesium Battery

High Resolution Image Download MS PowerPoint Slide The cathode performance is critical for developing a magnesium rechargeable battery, and spinel oxides MgM 2 O 4 (M = Mn/Fe/Co) show promise. However, (de)magnesiation and oxidative electrolyte decomposition are major issues. In this study, we investigated the microscopic mechanisms of dimethoxyethane (DME) oxidative decomposition on MgM 2 O 4 using density functional theory calculations. The study shows that demagnesiation promotes decomposition, and DME is most likely to decompose on MgMn 2 O 4 during charging compared to that on MgFe 2 O 4 and MgCo 2 O 4 . Density of states analysis reveals that the experimentally observed reactivity of MgMn 2 O 4 is due to the closeness in energy between the highest occupied molecular orbital of DME and the valence band maximum of MgMn 2 O 4 . Moreover, the fragmentation of DME occurs first, making oxidation easier. The oxidation potential order, Mn (3.05 V) < Co (3.27 V) < Fe (3.59 V), observed in the cyclic voltammograms, matches the calculated charge potentials, which has a certain effect on the DME decomposition.