Towards a Stable Organic Electrolyte for the Lithium Oxygen Battery

A new lithium‐ether‐derived chelate ionic liquid is synthesized to serve as an electrolyte for the Li‐O2 battery that is stable to metallic lithium, and whose ethereal framework is much more inherently stable to superoxide‐initiated hydrogen ion than the simple glyme, dimethoxyethane (DME). Reactions of chemically generated superoxide with this electrolyte show that virtually no decomposition products such as lithium formate are generated. When the electrolyte is employed in a Li‐O2 battery, a ten‐fold decrease in CO2 evolution is evident on charge by comparison to DME and greatly enhanced cycling stability is observed with TiC as a cathode support. A mechanism is proposed to account for the lowered reactivity, offering new insight into the stability of organic electrolytes in Li‐O2 batteries. This approach for electrolyte design is presented here for the first time, and it can be extended to other organic systems to provide a platform for the design of advanced electrolyte systems. The greatest challenge in the development of non‐aqueous lithium oxygen batteries is the necessity for materials that can withstand both reduction by metallic lithium and oxidation by some of the most reactive oxygen species (O2−, O22−, etc.). It is shown that hydrogen ion from solvent molecules by O2− can be prevented using systematic synthetic approaches.