Covalent organic frameworks for metal-gas batteries: fundamentals and applications

Metal-gas batteries (MGBs, e.g., Li-O₂, Li-CO₂, Zn-air batteries) are considered a promising candidate for next-generation energy conversion and storage systems due to their advantages of high energy density, environmental friendliness, and low cost. However, their practical applications are still limited by the slow kinetics of gas-involved reactions, insufficient electrolyte stability, and electrode passivation. Covalent organic frameworks (COFs) provide innovative solutions to break through these bottlenecks by virtue of their designable topology, high specific surface area, ordered pore channels and chemical stability. This review systematically summarizes the structural advantages of COFs in MGBs, and explores their synthesis strategies and electrocatalytic mechanisms. The application progress of COF-based materials as electrocatalysts, composite cathode materials, solid-state electrolytes, gas diffusion layers, etc. in Li-O₂, Li-CO₂ and Zn-air batteries is emphasized. In addition, this review deeply analyzes the current challenges faced by COF materials in MGBs and provides an outlook on the future development of COF materials in this field.