A Potassium‐Doped Perovskite‐Based Nanocomposite as an Efficient Bifunctional Oxygen Electrocatalyst for Rechargeable Zn‐Air Batteries

Abstract Bifunctional oxygen electrocatalysts play a crucial role in the performance of rechargeable zinc‐air batteries (ZABs), directly impacting key parameters such as capacity, round‐trip efficiency, and durability. The ideal electrocatalysts for ZAB air electrodes must exhibit high catalytic activity for both oxygen reduction and oxygen evolution reactions in alkaline medium. This study presents a potassium‐ion doping strategy to engineer the electron and defect structures of the perovskite oxide main phase, promoting phase separation to form a nanocomposite consisting of a perovskite phase and a secondary phase with an intergrowth structure. The resulting nanocomposite catalyst exhibits increased concentrations of Co 3+ and oxygen vacancies, enhanced hydrophilicity, and improved adsorption of oxygen intermediates. As a result, the catalyst with the optimized composition demonstrates exceptional bifunctional activity and superior durability, leading to extended cycling stability and improved energy conversion efficiency in ZABs. Notably, it achieves a 42% increase in power density compared to the potassium‐free pristine catalyst, a reduced voltage gap (ΔE = 0.83 V), and an extended cycle life of over 250 h. This work introduces a novel design paradigm for advanced metal‐air battery catalysts through potassium‐promoted defect‐engineered heterostructure manipulation of perovskite oxides.