A fundamental understanding of electrochemical reactions is essential to drive the practicality of batteries. The oxygen reduction reaction (ORR) that occurs on discharge in aprotic lithium-oxygen (Li-O) batteries, invariably encounters interference from impurities (e.g., protons) in practical environments. It has been shown that moderate proton-mediated ORR can improve discharge capacity without altering the overall pathway; however, the reactivity of protonated oxygen intermediates formed towards aprotic electrolytes during ORR, remains controversial and unexplored. Herein, we interrogate the reactivity of protonated oxygen intermediates at the model Au | propylene carbonate and Au | trimethyl phosphate interfaces containing phenol as the moderate proton source, using attenuated total reflection surface-enhanced infrared spectroscopy coupled with theoretical calculations. Direct spectroscopic evidence presents that the preferential reaction between superoxide and available protons to form protonated oxygen intermediates (e.g., HO), can significantly mitigate superoxide anion (O)-induced solvent degradations while not triggering additional secondary parasitic reactions. Consequently, practical Li-O batteries containing phenol have also exhibited improved electrochemical performance and reversibility. We believe that the fundamental insights will provide important lessons for future practical design (e.g., protons control of electrolytes) of Li-O batteries and other related electrochemical devices.

中文翻译：

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用原位表面增强红外光谱探测质子化氧中间体在非质子介质中的反应性

对电化学反应的基本了解对于推动电池的实用性至关重要。在实际环境中，非质子锂氧（Li-O）电池放电时发生的氧还原反应（ORR）总是会遇到杂质（例如质子）的干扰。研究表明，适度的质子介导的 ORR 可以在不改变整体路径的情况下提高放电容量；然而，ORR 过程中形成的质子化氧中间体对非质子电解质的反应性仍然存在争议和尚未探索。在此，我们探讨了 Au | 模型中质子化氧中间体的反应性。碳酸丙烯酯和Au |采用衰减全反射表面增强红外光谱结合理论计算，研究了含有苯酚作为温和质子源的磷酸三甲酯界面。直接光谱证据表明，超氧化物和可用质子之间优先反应形成质子化氧中间体（例如 H2O），可以显着减轻超氧阴离子（O）引起的溶剂降解，同时不会引发额外的次级寄生反应。因此，实用的含有苯酚的锂-氧气电池也表现出改进的电化学性能和可逆性。我们相信，这些基本见解将为锂氧电池和其他相关电化学装置的未来实际设计（例如电解质的质子控制）提供重要的经验教训。