Atomically Asymmetrical Ruthenium–Oxygen–Cobalt Sites Accelerate Oxygen Redox and Suppress Side Reactions for Stable Lithium–Oxygen Batteries

Development of aprotic lithium-oxygen (Li-O₂) batteries suffers from slow cathode reaction kinetics, numerous side reactions, and large polarization, which are intimately related to the discharge product of Li₂O₂. Here, we designed and prepared a modified Co₃O₄ nanoparticle with atomic Ru substitution at octahedral Co sites supported by carbon nanocages (RuCoO_<i>x</i>@HCNs) as a cathode catalyst. The asymmetrical octahedral Ru-O-Co units trigger a strong electron coupling effect, leading to charge redistribution and optimization of the d-orbital energy levels, thus facilitating oxygen activation and conversion into superoxide anions during discharging. More importantly, the Ru-O-Co units manifest high affinity for the intermediate LiO₂, inducing the rapid formation of unique nanoneedle-like Li₂O₂ on RuCoO_<i>x</i>@HCNs, avoiding the accumulation of byproducts and accelerating its decomposition during charge. These merit the Li-O₂ battery with RuCoO_<i>x</i>@HCNs to deliver a reduced polarization of 0.96 V and a prolonged lifespan of over 2200 h.