Decomposition pathway and stabilization of ether-based electrolytes in the discharge process of Li-O2 battery

Ether-based electrolytes with relatively high stability are widely used in Li-O2 batteries (LOBs) with high energy density. However, they are still prone to be attacked by reactive oxygen species. Understanding the degradation chemistry of ether-based solvent induced by reactive oxygen species is significant importance toward selection of stable electrolytes for LOBs. Herein, we demonstrate that a great amount of H2 gas evolves on the Li anode during the long-term discharge process of LOBs, which is due to the electrolyte decomposition at the oxygen cathode. By coupling with in-situ and ex-situ characterization techniques, it is demonstrated that O2− induces the H-abstraction of tetraethylene glycol dimethyl ether (TEGDME) to produce a large amount of H2O at cathode, and this H2O migrates to Li anode and produce H2 gas. Based on the established experiments and spectra, a possible decomposition pathway of TEGDME caused by O2− at the discharge process is proposed. And moreover, three types of strategies are discussed to inhibit the decomposition of ether-based electrolytes, which should be highly important for the fundamental and technical advancement for LOBs.