Advanced bifunctional catalyst design for rechargeable zinc-air batteries

Zinc-air batteries have attracted more attention due to their high energy density, high safety, low cost, and environmental friendliness. Nevertheless, sluggish oxygen reaction kinetics at the air electrode seriously compromises their power density and cycling stability. As one of the main components, the catalyst significantly impacts the performance of zinc-air batteries. Finding high-performance bifunctional catalysts for both the oxygen reduction reaction and oxygen evolution reaction is of great importance for the practical application of zinc-air batteries. In this review, the history, merits and challenges of zinc-air batteries are introduced, the working principle of zinc-air batteries and the mechanisms of ORR and OER in air electrodes are analyzed deeply, and the research status of bifunctional catalysts that promote both ORR and OER kinetics is systematically reviewed. Finally, the pending problems that need to be solved in future research and the practical application of bifunctional catalysts in zinc-air batteries are discussed. This review aims to provide a valuable reference for the development of bifunctional catalysts for zinc-air batteries.