Glyme Solvent Decomposition on Spinel Cathode Surface in Magnesium Battery
Wenchong Zhou, Chenchao Xu, Bo Gao, Masanobu Nakayama, Shunsuke Yagi, Yoshitaka Tateyama
Abstract
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.