Long-unresolved discrepancies in the oxidation mechanism of lithium peroxide (Li₂O₂) impede electrode/electrolyte development for Li-O₂ batteries. In this study, we report direct evidence of the formation of soluble LiO₂ upon the oxidation of Li₂O₂ and reveal a strong solvent-controlled Li₂O₂-oxidation reaction mechanism. We exploit a thin-film rotating ring-disk electrode to show that soluble LiO₂ is generated when oxidizing Li₂O₂ in high-donicity solvent but is absent in low-donicity glyme-based solvent. Synchrotron-based X-ray absorption near-edge structure spectroscopy further proved the presence of LiO₂ upon Li₂O₂ oxidation in high-donicity solvent but not in low-donicity solvent. We show that preferential formation of soluble LiO₂ in the high-donicity solvent could account for poor cycling stability, which suggests that strategies that bypass the formation of soluble LiO₂ upon Li₂O₂ oxidation are critical. Our work offers new insights in resolving the discrepancy in Li-O₂ charging mechanism and design strategies to achieve efficient and long-life Li-O₂ batteries.

长期未解决的过氧化锂（Li ₂ O ₂）氧化机理差异阻碍了Li-O ₂电池的电极/电解质发展。在这项研究中，我们报告了在Li ₂ O ₂氧化后形成可溶性LiO _2的直接证据，并揭示了由溶剂控制的强Li ₂ O ₂氧化反应机理。我们利用薄膜旋转环盘电极表明可溶性LIO ₂生成氧化锂时₂ ö ₂在高强度溶剂中不存在，而在低强度基于甘醇二甲醚的溶剂中则不存在。基于同步加速器的X射线吸收近边缘结构光谱进一步证明了Li ₂ O ₂在高强溶剂中氧化时存在LiO ₂，而在低强溶剂中则没有。我们表明，在高强溶剂中优先形成可溶性LiO ₂可以解决循环稳定性差的问题，这表明在Li ₂ O ₂氧化时绕过可溶性LiO ₂形成的策略至关重要。我们的工作为解决Li-O ₂充电机制和设计策略方面的差异提供新见解，以实现高效且长寿命的Li-O_2个电池。