Emerging High-Entropy Alloys for Rechargeable Zinc-Air Batteries: From Fundamental Concepts to Advanced...

Rechargeable zinc-air batteries (ZABs) are promising next-generation energy-storage systems owing to their high theoretical energy density, intrinsic safety, low cost, and environmental sustainability. However, their practical application is limited by the sluggish kinetics and poor durability of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). High-entropy alloys (HEAs), comprising five or more principal elements, have emerged as promising electrocatalysts owing to their high configurational entropy, lattice distortion, abundant active sites, and tunable electronic structures. This review highlights the evolution and fundamentals of HEAs, including their thermodynamic principles, structural characteristics, and core effects, with particular emphasis on their development for rechargeable ZABs. We systematically discuss HEA characterization, composition engineering, synthesis strategies, and structure-property-performance relationships. Recent advances in HEA-based ORR/OER electrocatalysts are critically evaluated, emphasizing multielement synergy, active-site regulation, and electronic-structure modulation. Their integration into practical ZABs is further assessed in terms of power density, energy efficiency, rate capability, and cycling stability. Finally, challenges associated with scalable synthesis, compositional control, bifunctional activity, durability, characterization, and mechanistic understanding are identified, alongside future perspectives toward commercially viable, durable, and efficient HEA-based ZABs.