Engineering Directional Ion Transport Channels in Three‐Dimensional Covalent Organic Frameworks for High‐Performance Sodium‐Ion Batteries

ABSTRACT Covalent organic frameworks (COFs) with abundant redox‐active sites are promising electrode materials for sodium‐ion batteries (SIBs). However, conventional design strategies are often limited by sluggish Na + transport and low utilization of active sites. Here, we report a pair of 3D COFs (COF‐O and COF‐H). In COF‐O, the C═O groups are precisely oriented toward the pore channels, allowing the O atoms to serve as effective Na + storage sites. In contrast, COF‐H contains only C–H groups within the pores, which lack Na + storage capability. When employed as an anode material in SIBs, COF‐O exhibits a high specific capacity of 318 mAh/g (1.9 times that of COF‐H) and excellent cycling stability over 6000 cycles. In situ spectroscopic studies combined with theoretical calculations reveal that the C═O groups in COF‐O act as efficient Na + storage sites, effectively enhancing the capacity and accelerating Na + transport kinetics. This work demonstrates that precisely orienting functional groups in 3D COFs can create effective ion transport channels, providing a promising strategy for designing advanced organic electrode materials for SIBs.