Lithium–oxygen batteries promise high energy but suffer from poor cycle life owing to the generation of highly reactive singlet oxygen ¹O₂, which rapidly deactivates the electrode and the electrolyte. Here we demonstrate an effective strategy to suppress ¹O₂ using redox mediators. Using operando spectroscopy techniques, we show that 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), as a model redox mediator, drastically reduces ¹O₂ formation, increases the yield of ground state ³O₂, and reduces the by-product generation. The ¹O₂ suppression effect is attributed to an increased intersystem crossing rate induced by redox mediators, with which the relaxation of a singlet-state intermediate to a triplet-state one is accelerated. We further show that this ¹O₂ suppression effect applies universally across six common redox mediators with up to three orders of magnitude higher ¹O₂ suppression efficiency compared to 1,4-diazabicyclo[2.2.2]octane (DABCO), the most efficient quencher used in Li–O₂ batteries to date. From the comparison of the investigated mediators we discuss the plausible governing principle dictating redox mediators’ effectiveness in suppressing ¹O₂. Our study achieves effective ¹O₂ suppression and provides guidelines for designing redox mediators for efficient and reversible lithium–oxygen batteries.

中文翻译：

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使用氧化还原介体抑制锂氧电池中的单线态氧生成

锂氧电池有望提供高能量，但由于会产生高反应性单线态氧¹ O ₂，因此循环寿命很短，单氧¹ O ₂会迅速使电极和电解质失活。在这里，我们演示了使用氧化还原介体抑制¹ O ₂的有效策略。使用操作光谱技术，我们显示2,2,6,6-四甲基-1-哌啶基氧基（TEMPO）作为模型氧化还原介体，可大幅减少¹ O _2的形成，增加基态³ O ₂的产率，并降低副产品的产生。的¹ Ò ₂抑制作用归因于由氧化还原介体引起的系统间交叉速率的增加，由此加速了单重态中间体向三重态中间体的松弛。我们进一步表明，这种¹ O ₂抑制作用普遍适用于六个常见的氧化还原介体，与最有效的1,4-二氮杂双环[2.2.2]辛烷（DABCO）相比，其¹ O ₂抑制效率高出三个数量级。迄今为止，Li–O ₂电池中使用的淬火剂。通过对所研究的介体的比较，我们讨论了指导氧化还原介体抑制¹ O ₂有效性的合理控制原则。。我们的研究实现了有效的¹ O ₂抑制，并为设计用于高效可逆锂氧电池的氧化还原介体提供了指导。