Covalent organic framework membranes for rechargeable electrochemical energy storage devices: chemistry, fabrication, and future opportunities

Covalent organic frameworks (COFs) are crystalline porous polymers formed by linking organic monomers through covalent bonds. Their exceptional surface areas, uniform pore structures and adjustable chemical properties make COFs highly promising for ion conduction and selection. Advances in COF chemistry now allow modifications at molecular and atomic scales. This progress supports the design of COF-based membranes tailored for energy storage applications. In this review, we present the fundamental features of COF membranes with a focus on their chemical synthesis and structural features. We further examine their advantages in ion selectivity, interface stabilization, and dendrite suppression, alongside diverse fabrication strategies such as composite approaches, layer-by-layer stacking, in situ growth, interfacial polymerization, solvothermal synthesis, chemical vapor deposition, and electrophoretic deposition. The applications of these membranes in various rechargeable electrochemical energy storage (REES) devices are also discussed, including lithium-ion batteries, lithium metal batteries, lithium-sulfur batteries, redox flow batteries, hydrogen fuel cells, and aqueous zinc-ion batteries. Lastly, we summarize recent research progress, highlight key challenges in COF membranes development, and provide insights into future directions for achieving high-performance REES devices.