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 À 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 ptype 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 À dual-ions as charge carriers. This work paves the avenue toward novel organic cathodes in RABs.

Covalent Organic Frameworks as Promising Electrode Materials for High-Valent Ion Rechargeable Batteries

“…The flexible design of active groups endows the COF materials with diverse charge storage mechanisms and guarantees their ideal reversible capacity. Liu et al 41 + and AlCl 4 − as charge carriers (Figure 6e). At 0.3 mV s −1 , the CV curves indicated highly reversible electrochemical reactions and enhanced capacity of 2D-NT-COF30 composited with 30% carbon nanotube (Figure 6f).…”

“…(h) 2D 27 Al– 1 H HETCOR spectra of the 2D-NT-COF30 electrode in the discharged state. Reprinted with permission from ref . Copyright 2023 The Authors.…”

“…The flexible design of active groups endows the COF materials with diverse charge storage mechanisms and guarantees their ideal reversible capacity. Liu et al synthesized 2D-PT-COF and 2D-NT-COF using 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)trianiline (TTA), pyromellitic dianhydride (PMDA), and NTCDA as monomers, respectively. 13 C nuclear magnetic resonance (NMR) spectra identified a unique structure integrated by n-type imide and p-type triazine, realizing AlCl 2 + and AlCl 4 – as charge carriers (Figure e).…”

Organic electrodes based on redox-active covalent organic frameworks for lithium batteries

“…COFs have recently been explored as electrode materials in different metal–ion (including multivalent) batteries 34 (Li + , 35,36 Na + , 37,38 K + , 39,40 Mg 2+ , 41 Ca 2+ , 42 Zn 2+ , 43 Al 3+ , 44,45 etc. ) and lithium–sulphur (Li–S) batteries.…”

Covalent Organic Frameworks as Model Materials for Fundamental and Mechanistic Understanding of Organic Battery Design Principles

“…16 Furthermore, due to the modular construction principle and the vast variety of organic reactions to construct COFs, the molecular building blocks are precisely assembled into a crystalline framework, align donor− acceptor moieties, control the planarity, and retain the conjugation of the framework, which all tune the polymeric band structure and electronically activate the redox functionalities of the framework. 17−19 Owing to these fascinating properties and additionally the controllable pore structure, large surface area, simple surface/structural modification, and high thermal and chemical stability, COFs have been investigated as intriguing electrode materials in reversible energy storage, especially in secondary ion batteries (Li + , 20 Na + , 21 K + , 22 Mg 2+ , 23 Ca 2+ , 24 Zn 2+ , 25,26 , Al 3+ , 27 etc.) (Figure 1A).…”