Metal–air batteries promise high gravimetric energy and low material cost but suffer from poor cycle life due to severe cathode side reactions. Here, the reactivity of metal superoxide is demonstrated to play a decisive role in determining the cathode reversibility under true ambient air. The K⁺-based oxygen electrode is much more robust against H₂O/CO₂ contamination because the stability of KO₂ is higher than those of LiO₂ and NaO₂. As a result, ambient air batteries using 1.0 mA cm^–2 at 0.25 mAh cm^–2 (500 h, 1000 cycles) and at 1.0 mAh cm^–2 (>800 h, >400 cycles) were demonstrated. Online electrochemical mass spectrometry and Fenton's tests reveal that the accumulation of carbonate-based side product is negligible even under true ambient air (i.e., 0.07 mol ‰ of KO₂ per cycle over 500 cycles). This work reveals key factors in achieving reversible nonaqueous air cathode reactions and demonstrates unprecedented long-life rechargeable ambient air batteries.

中文翻译：

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在真实环境空气下实现稳定的非水空气阴极

金属空气电池具有很高的重量能量和较低的材料成本，但由于严重的阴极副反应而导致循环寿命差。在此，证明金属超氧化物的反应性在确定真实环境空气下的阴极可逆性中起决定性作用。由于KO ₂的稳定性高于LiO ₂和NaO ₂的稳定性，因此基于K ⁺的氧电极对H ₂ O / CO _2的污染更为牢固。其结果是，使用1.0毫安厘米环境空气电池^-2 0.25毫安厘米^-2（500小时，1000次循环），并在1.0毫安厘米^-2（> 800小时，> 400个循环）被证明。在线电化学质谱法和Fenton测试表明，即使在真实的环境空气中（即500个循环中每个循环0.07 mol‰KO ₂），碳酸盐基副产物的累积也可以忽略不计。这项工作揭示了实现可逆的非水空气阴极反应的关键因素，并展示了前所未有的长寿命可充电环境空气电池。