A stable lithium-oxygen battery electrolyte based on fully methylated cyclic ether.

Ether-based electrolytes are commonly used in Li-O2 batteries (LOBs) because of their relatively high stability. But they are still prone to be attacked by superoxides or singlet oxygen via hydrogen abstract reactions, which leads to performance decaying during long-term operation. In this study, we propose a methylated cyclic ether, 2,2,4,4,5,5-hexamethyl-1,3-dioxolane (HMD), as a stable electrolyte solvent for LOBs. Such compound doesn't contain any hydrogen atom on the alpha-carbon of the ether, and thus avoids the hydrogen abstraction reactions. As the result, this solvent exhibits excellent stability with the presence of superoxide or singlet oxygen. And the CO2 evolution during charge process is prohibited. The LOB with HMD based electrolyte was able to run up to 157 cycles, 4 times longer than with 1,3-dioxolane (DOL) or 1,2-dimethoxyethane (DME) based electrolytes.