RuO₂ displays excellent bifunctional catalysis towards the oxygen reduction and evolution reactions of Li-O₂ battery. Nevertheless, how the solid catalyst successively catalyzes solid Li₂O₂ formation and decomposition, confronting passivation and loss of RuO₂/Li₂O₂ contact, during discharging and charging remains a mystery. Here we report operando observations of RuO₂ catalyzed oxygen reduction and evolution reactions of Li₂O₂ by utilizing a liquid cell scanning transmission electron microscope. Upon discharging, RuO₂ obviously accelerates formation of soluble LiO₂ intermediates and acts as preferential sites of Li₂O₂ precipitation. During charging, the catalytic activation of RuO₂ takes place at electrolyte-RuO₂-Li₂O₂ triple-phase interfaces. Importantly, RuO₂ not only catalyzes the decomposition of directly contacted Li₂O₂, but also promotes oxidation of soluble LiO₂ for rapid dissolution of isolated Li₂O₂ nanoparticles by a chemical comproportionation reaction. The observation unveils how RuO₂ catalyzes the formation and decomposition of Li₂O₂ during discharging and charging and provides nanoscale insights into cathodic reactions of Li-O₂ batteries with solid catalysts.

RuO ₂对Li-O ₂电池的氧还原和放出反应显示出出色的双功能催化作用。然而，在放电和充电过程中，固体催化剂如何连续地催化固体Li ₂ O _2的形成和分解，面对RuO ₂ / Li ₂ O ₂接触的钝化和损失仍然是一个谜。在这里，我们报告利用液体细胞扫描透射电子显微镜观察RuO ₂催化的Li ₂ O ₂的氧还原反应和析出反应的操作性观察。放电后，RuO ₂明显加速了可溶性LiO ₂中间体的形成，并成为Li ₂ O ₂沉淀的优先位。在充电期间，RuO ₂的催化活化发生在电解质-RuO ₂ -Li ₂ O ₂三相界面上。重要的是，RuO ₂不仅催化直接接触的Li ₂ O ₂的分解，而且还促进了可溶性LiO _2的氧化，从而通过化学平衡反应快速溶解了分离出的Li ₂ O ₂纳米颗粒。观察揭示了RuO ₂如何在放电和充电过程中催化Li ₂ O ₂的形成和分解，并提供纳米级洞察力，以了解Li-O ₂电池与固体催化剂的阴极反应。