Employing organic redox mediators (ORMs) for lithium–oxygen (Li–O₂) batteries has emerged as an important strategy to suppress charging overpotentials. Judicious molecular designs of ORMs can also tailor their redox potential and electron-transfer rate to optimize the catalytic efficiency. However, the stability of ORMs in Li–O₂ cells was scarcely studied. Here, the catalytic efficiency and stability of several important ORMs are assessed through in situ gas analysis and reactivity tests with singlet oxygen. Some well-known ORMs are detrimentally decomposed during the first cycle in Li–O₂ cells, whereas nitroxyl-radical-based ORMs bear the most stable and efficient response. Analogous nitroxyl-radical derivatives further increase round-trip energy efficiency and electron-transfer kinetics. This study underlines chemical stability aspects of ORMs, which are mandatory for the long-term cyclability in Li–O₂ cells. We emphasize that besides the importance of ORMs in these systems and their proper selection, an effective operation of Li–O₂ cells depends also strongly on the stability of the carbonaceous cathodes and the electrolyte solutions. The stability of all the components in these systems is inter-related.

中文翻译：

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锂氧电池中有机氧化还原介体作为移动催化剂的氧化稳定性

使用有机氧化还原介体（ORM）制备锂氧（Li–O ₂）电池已成为抑制充电超电势的重要策略。明智的ORM分子设计还可以调整其氧化还原电势和电子传输速率，以优化催化效率。但是，很少研究ORM在Li–O ₂细胞中的稳定性。在这里，通过原位气体分析和单线态氧的反应性测试评估了几种重要ORM的催化效率和稳定性。在Li–O ₂的第一个循环中，一些著名的ORM有害分解细胞，而基于硝酰自由基的ORM则具有最稳定，最有效的反应。类似的硝酰基-自由基衍生物进一步提高了往返能量效率和电子转移动力学。这项研究强调了ORM的化学稳定性，这对于Li–O ₂细胞的长期循环性是必不可少的。我们强调，除了ORM在这些系统中的重要性及其正确选择外，Li-O ₂电池的有效运行还强烈取决于碳质阴极和电解质溶液的稳定性。这些系统中所有组件的稳定性是相互关联的。