Novel strategies for low overpotential metal–air batteries

This review article provides a comprehensive overview of the recent advancements in metal-air batteries, including zinc-air, aluminum-air, and lithium-air batteries, with a particular emphasis on strategies to mitigate overpotentials and enhance energy efficiency and cycling stability. Metal-air batteries have garnered significant attention due to their exceptionally high theoretical energy densities. However, their practical applications are impeded by substantial overpotentials during charge and discharge processes, which are primarily attributed to kinetic limitations at electrode interfaces, mass transport restrictions of reactants and products, and inherent system resistances. Addressing these challenges, this review explores various approaches to lower overpotentials from three perspectives: electrolyte optimization, cathode development, and anode protection. In the realm of electrolytes, organic, aqueous, hybrid, and novel metal-hydrogen peroxide systems are discussed. For cathodes, efficient electrocatalysts for oxygen reduction and evolution reactions (ORR/OER) are developed through inorganic polymer/biomass-assisted and in situ synthesis methods. Anode strategies focus on suppressing self-corrosion and parasitic reactions, exemplified by the use of cyanuric acid as a molecular armor for aluminum anodes. Additionally, the application of external fields, such as photonic and magnetic assistance, is highlighted for their role in reducing charging voltage and improving cycling stability in metal-air batteries. Collectively, these strategies offer theoretical and technological insights for designing low-overpotential metal-air batteries, potentially revolutionizing energy storage applications.