Truxenone‐Based Covalent Organic Framework With Extended π‐Conjugation and Multiple Active Sites for Symmetric All‐COF Sodium‐Ion Batteries

ABSTRACT Covalent organic frameworks (COFs) have emerged as promising organic electrodes for various batteries owing to their structural diversity, chemical stability, and tunable functionality. However, the development of advanced COFs‐based batteries remains challenging due to their intrinsic poor conductivity and insufficient utilization of redox‐active sites. Herein, we design a truxenone‐based covalent organic framework (TRO‐DH‐COF) featuring extended π‐conjugation and multiple redox‐active sites, which is further integrated with conductive carbon nanotubes (CNTs) and fabricated into the first symmetric all‐COF sodium‐ion batteries (ACSIBs). As a cathode, the TRO‐DH‐COF@CNT50 delivers an impressive specific capacity of 227.3 mAh g −1 at 0.1 A g −1 , outstanding rate capability (152.8 mAh g −1 at 10 A g −1 ), and exceptional cycle lifespan with a reversible capacity of 154.8 mAh g −1 after 4000 cycles at 2 A g −1 . Experimental characterization and theoretical calculations reveal that the efficient and reversible charge storage process proceeds successively on C═O and C═N groups. Expectedly, the symmetrical ACSIBs constructed with TRO‐DH‐COF@CNT50 as both cathode and anode displays outstanding energy density of 144.1 Wh kg −1 along with excellent cycling durability over 600 cycles at 2 A g −1 . This work opens a new avenue for designing high‐performance SIBs and significantly advances the development of novel alkali‐metal ion storage technologies.