Ruthenium-based composites: Unlocking the application potential of rechargeable zinc-air batteries

Rechargeable zinc-air batteries (ZABs) hold great promise for sustainable energy storage but suffer from large polarization gaps due to sluggish oxygen electrocatalysis. While conventional bifunctional catalysts like carbon-based composites offer high activity and transition metal compounds provide alternatives, they face critical limitations: inherent electrochemical corrosion of carbon in alkaline electrolytes and irreversible phase transformations of transition metals during cycling, leading to ZABs performance decay. Ru-based composite catalysts emerge as a compelling solution, demonstrating superior bifunctional activity and exceptional stability in ZABs. This review systematically analyzes the rationale for developing Ru-based composites by contrasting their performance advantages. We further summarized the design strategy of Ru-based composites, including interface engineering, doping engineering, and single-atom engineering, to balance the activity-stability-cost trilemma through electronic modulation, oxidation-resistance design, Ru minimization, and synergistic functionality. By outlining these advances and future directions, this work aims to guide the development of efficient, durable, and economically viable Ru-based catalysts for next-generation ZABs.