The Origin of Reduced Reductive Stability of Ion-Solvent Complexes on Alkali and Alkaline Earth Metal Anodes.

The intrinsic instability of organic electrolytes seriously impedes the practical applications of high-capacity metal anodes, such as lithium and sodium metal anodes. The ion-solvent complexes can even further promote the decomposition of electrolytes on metal anodes. Herein, first-principles calculations were performed to investigate the origin of the reduced reductive stability of ion-solvent complexes. Both ester and ether electrolyte solvents are selected to interact with Li+, Na+, K+, Mg2+, and Ca2+. The LUMO energy levels of ion-ester complexes exhibit a linear relationship with the binding energy, regulated by the ratio of carbon atomic orbital in the LUMO. While LUMOs of ion-ether complexes are composed by the metal atomic orbitals. This work uncovers the intrinsic reasons why ion-solvent complexes can reduce the reductive stability of electrolytes, reveals two different mechanisms for ester and ether electrolytes, and provides a theoretical understanding of the electrolyte-anode interfacial reactions and a mechanistic guidance to electrolyte and metal anode design for safe rechargeable batteries.