Interfacial engineering of hollow multishelled structure for metal-air batteries: Reaction mechanism and material design

Metal-air batteries (MABs) possess high theoretical energy density, but their practical applications are often restricted by unstable multiphase interfaces as well as mismatched mass transport and reaction kinetics. This review first outlines the operating principles of non-aqueous, aqueous, and solid-state MABs, highlights their key differences, and then summarizes the evolution characteristics of major interfaces during cycling, including the metal anode/electrolyte interface, the air cathode/electrolyte interface, and separator/electrolyte contact interfaces. The typical problems encountered in MABs include pore blockage caused by product accumulation, which reduces the effective reaction area of the cathode; increased resistance resulting from electrolyte decomposition and side reactions; anode corrosion or passivation accompanied by non-uniform deposition; and contact degradation induced by volume change and internal stress. We discuss the hollow multishelled structure (HoMS) as a potential platform, which can play roles in product buffering, transport pathway maintenance, and structural cushioning. Finally, we emphasize the importance of quantitative validation, coordinated interface design, and performance evaluation under practical working conditions, with the support of data analysis and AI tools.