Redox‐Bipolar Covalent Organic Framework Cathode for Advanced Sodium‐Organic Batteries

Abstract Redox‐active covalent organic frameworks (COFs) are promising candidates for sodium‐ion batteries (SIBs). However, the construction of redox‐bipolar COFs with the anions and cations co‐storage feature for SIBs is rarely reported. Herein, redox‐bipolar COF constructed from aniline‐fused quinonoid units (TPAD‐COF) is developed as the cathode material in SIBs for the first time. The unique integration of conductive aniline skeletons and quinone redox centers endows TPAD‐COF with high ionic/electrical conductivity, abundant redox‐active sites, and fascinating bipolar features. Consequently, the elaborately tailored TPAD‐COF cathode exhibits higher specific capacity (186.4 mAh g⁻¹ at 0.05 A g⁻¹) and superior cycling performance (over 2000 cycles at 1.0 A g⁻¹ with 0.015% decay rate per cycle). Impressively, TPAD‐COF also displays a high specific capacity of 101 mAh g⁻¹ even at −20 °C. As a proof of concept, all‐organic SIBs (AOSIBs) are assembled using TPAD‐COF cathode and disodium terephthalate anode, which also show impressive electrochemical properties, indicating the potential application of TPAD‐COF cathode in AOSIBs. The work will pave the avenue toward advanced COFs cathode for rechargeable batteries through rational molecular design.