Dual‐Redox Conjugated Bipolar Covalent Organic Framework Enables High‐Voltage Symmetric Proton Batteries

Abstract

ABSTRACT Symmetric all‐organic proton batteries (SAOPBs) attract increasing attention for large‐scale energy storage due to their safe and superior rate performance, which is severely limited by the lack of suitable bipolar electrode materials that integrate reversible dual‐redox activity and high operating voltage within a single structure. Herein, we report a bipolar covalent organic framework (TAPT‐HAT‐COF) as both cathode and anode in symmetric proton battery. In this COF, the electron‐deficient pyrazine/carbonyl units and electron‐rich phenylimine groups establish two independent and reversible redox couples, achieving a high operating voltage of up to 0.83 V. Combined with in situ FTIR spectroscopy and theoretical calculations, TAPT‐HAT‐COF shows bipolar charge storage mechanism with the C═N and C═O groups served as reversible redox centers. Benefiting from the fully conjugated structure and abundant active sites, the assembled SAOPB exhibits high specific capacity of 108.5 mAh g −1 under 5 A g −1 with stable cycling over 3000 cycles. Moreover, when applied in a practical pouch cell, which delivers a specific capacity of 145.8 mAh g −1 at 0.5 A g −1 , confirming the material's potential for practical applications. The work can provide viable design strategy and model of bipolar COF materials for symmetric energy storage systems.