Advances in hexaazatriphenylene-based COFs for rechargeable batteries: from structural design to electrochemical performance

Abstract

As commercial batteries reach capacity and energy density limits, especially with graphite anodes and transition metal cathodes, the need for advanced alternatives grows. Organic electrodes offer the promise of high capacity, sustainability, and tunable structures. Among them, hexaazatriphenylene (HATP)-based covalent organic frameworks (COFs) have gained considerable attention because of their distinctive characteristics. HATP-based COFs are formed with an electronegative skeleton within one-dimensional channels, and exhibit a strong affinity for metal ions (Li⁺, Na⁺, K⁺, Zn²⁺). Their distinct structure significantly enhances both ion transport and reaction kinetics. Moreover, HATP-based COFs exhibit highly ordered, permanent porosity and large surface areas, while their dense active sites and tunable conductivity facilitate rapid redox processes and enhanced capacity, leading to improved electrochemical performance. Additionally, their conjugated nature ensures robust physical and chemical stability, minimizing side reactions and maintaining structural integrity and cycling stability. As a result, HATP-based COFs are particularly well-suited for various rechargeable batteries, including lithium-ion, sodium-ion, potassium-ion, and aqueous zinc-ion batteries. This review explores the development and design principles of HATP-based COFs, analyzes their electrochemical performance and redox mechanisms, and addresses the challenges and future directions for their application in energy storage technologies.