Aprotic alkali metal–O₂ batteries face two major obstacles to their chemistry occurring efficiently, the insulating nature of the formed alkali superoxides/peroxides and parasitic reactions that are caused by the highly reactive singlet oxygen (¹O₂). Redox mediators are recognized to be key for improving rechargeability. However, it is unclear how they affect ¹O₂ formation, which hinders strategies for their improvement. Here we clarify the mechanism of mediated peroxide and superoxide oxidation and thus explain how redox mediators either enhance or suppress ¹O₂ formation. We show that charging commences with peroxide oxidation to a superoxide intermediate and that redox potentials above ~3.5 V versus Li/Li⁺ drive ¹O₂ evolution from superoxide oxidation, while disproportionation always generates some ¹O₂. We find that ¹O₂ suppression requires oxidation to be faster than the generation of ¹O₂ from disproportionation. Oxidation rates decrease with growing driving force following Marcus inverted-region behaviour, establishing a region of maximum rate.

非质子碱金属-O _{2电池面临两个主要障碍，以使其化学反应有效发生，即形成的碱金属超氧化物/过氧化物的绝缘性和由高反应性单线态氧 (} ¹ O ₂ )引起的寄生反应。氧化还原介体被认为是提高可充电性的关键。然而，尚不清楚它们如何影响¹ O ₂的形成，这阻碍了它们的改进策略。在这里，我们阐明了介导的过氧化物和超氧化物氧化的机制，从而解释了氧化还原介质如何增强或抑制¹ O ₂形成。我们表明充电开始于过氧化物氧化成超氧化物中间体，并且氧化还原电势高于 ~3.5 V 相对于 Li/Li ⁺驱动¹ O ₂从超氧化物氧化中析出，而歧化总是产生一些¹ O ₂。我们发现¹ O ₂抑制需要比歧化产生¹ O _{2更快的氧化。}氧化速率随着 Marcus 倒置区域行为后驱动力的增加而降低，建立最大速率区域。