Application of covalent organic frameworks as electrode materials for supercapacitors

Supercapacitors have garnered significant attention due to their superior power density, excellent cycle stability, and fast charge/discharge rates. The properties of the electrode materials determine the charge storage performance of supercapacitors. Covalent organic frameworks (COFs) are a novel class of crystalline porous polymer materials with uniform nanoscale pores, large specific surface areas, and tunable redox-active groups within the framework, which can be tuned to suit specific applications. They have flexible molecular designs and synthetic strategies, demonstrating their strong application potential in the field of energy storage. Most COFs exhibit poor inherent conductivity and low utilization of active sites, resulting in incomplete electrochemical performance. Hybrid systems can be developed by incorporating redox-active groups, hydrogen bonding, or combining COFs with other materials to improve the energy storage performance of COFs materials. In this review article, the background of COFs is summarized, including a brief introduction, design strategy, and synthesis methods. It also discusses their applications in supercapacitors and is categorized into: pristine COFs, modified COFs, and COF matrix composites. Finally, the review addresses the challenges that remain for the practical application of these materials in supercapacitors.