J. Liu, Y.J. Li, Y.J. Ding, L.S. Wu, J.Q. Qin, T.L. Chen, C.X. Meng, F. Zhou, X.K. Ma * and Z.-S. Wu *

Angewandte Chemie International Edition, 2024, Accepted.

The addition of a redox mediator as soluble catalyst into electrolyte can effectively overcome the bottlenecks of poor energy efficiency and limited cyclability for Li-O2 batteries caused by passivation of insulating discharge products and unfavorable byproducts. Herein we report a novel soluble catalyst of bifunctional imidazolyl iodide salt additive, 1,3-dimethylimidazole iodide (DMII), to successfully construct highly efficient and durable Li-O2 batteries. The anion I− can effectively promote the charge transport of Li2O2 and accelerate the redox kinetics of oxygen reduction/oxygen evolution reactions on the cathode side, thereby significantly decreasing the charge/discharge overpotential. Simultaneously, the cation DMI+ forms an ultrathin stably solid-electrolyte interphase film on Li metal, greatly inhibiting the shuttle effect of I− and improving the stability of anode. Using this DMII additive, our Li-O2 batteries achieve an extremely low voltage of 0.52 V and ultra-long cycling stability over 960 h. Notably, up to 95.8% of the Li2O2 yield further proves the reversible generation/decomposition of Li2O2 without the occurrence of side reactions. Both experimental and theoretical results disclose that DMII enables Li+ easily solvated, testifying the dominance of the solution-induced reaction mechanism. This work provides the possibility to design the soluble catalysts towards high-performance Li-O2 batteries.