Redox‐Bipolar Polyimide Two‐Dimensional Covalent Organic Framework Cathodes for Durable Aluminium Batteries

Abstract Emerging rechargeable aluminium batteries (RABs) offer a sustainable option for next‐generation energy storage technologies with low cost and exemplary safety. However, the development of RABs is restricted by the limited availability of high‐performance cathode materials. Herein, we report two polyimide two‐dimensional covalent organic frameworks (2D‐COFs) cathodes with redox‐bipolar capability in RAB. The optimal 2D‐COF electrode achieves a high specific capacity of 132 mAh g −1 . Notably, the electrode presents long‐term cycling stability (with a negligible ≈0.0007 % capacity decay per cycle), outperforming early reported organic RAB cathodes. 2D‐COFs integrate n‐type imide and p‐type triazine active centres into the periodic porous polymer skeleton. With multiple characterizations, we elucidate the unique Faradaic reaction of the 2D‐COF electrode, which involves AlCl 2+ and AlCl 4 − dual‐ions as charge carriers. This work paves the avenue toward novel organic cathodes in RABs.