Highly Efficient Oxygen Evolution Reaction in Rechargeable Lithium-Oxygen Batteries with Triethylphosphate-Based Electrolytes

Aprotic lithium-oxygen (Li-O-2) batteries are promising candidates for next-generation energy storage devices because of their much higher potential energy density than Li-ion batteries. However, the practical application of rechargeable Li-O-2 batteries has been limited by poor cycle performance, especially the side reactions that lower the oxygen reaction efficiency at the positive electrode. The present study demonstrated that when the triethylphosphate-based electrolyte contains lithium nitrate and triethylphosphate forms a solvated complex by coordinating with Li ions, the O-2 evolution rate could reach almost 100 % of that of the ideal two-electron reaction (O-2/e(-) = 0.5) during the most part of the charging process, with the total oxygen evolution yield exceeding 90 %. These results are useful for designing electrolytes for rechargeable Li-O-2 batteries with high energy densities.