Atomically Dispersed Ta-O-Co Sites Capable of Mitigating Side Reaction Occurrence for Stable Lithium-Oxygen Batteries

The side reactions accompanying the charging and discharging process, as well as the difficulty in decomposing the discharge product lithium peroxide, have been important issues in the research field of lithium-oxygen batteries for a long time. Here, single atom Ta supported by Co3O4 hollow sphere was designed and synthesized as a cathode catalyst. The single atom Ta forms an electron transport channel through the Ta-O-Co structure to stabilize octahedral Co sites, forming strong adsorption with reaction intermediates and ultimately forming a film-like lithium peroxide that is highly dispersed. More importantly, the formation of the Ta-O-Co structure can reduce the vacancy formation energy on the catalyst surface, accelerate oxygen activation and conversion into superoxide anions, promote the rapid conversion of strong oxidizing intermediate lithium superoxide into lithium peroxide, avoid the oxidation of lithium superoxide to the electrode and electrolyte, reduce the occurrence of side reactions, and mitigate the production of byproduct lithium carbonate. The overpotential of the battery is reduced significantly, and the reversibility and cycling stability of the battery are improved. This study provides a practical and feasible direction for mitigating the side reaction and improving the performance of the battery.