Hexaazatriphenylene–Diaminobenzidine Covalent Organic Framework: A Promising Nitrogen Abundant Material for Electrochemical Energy Storage Applications

Covalent organic frameworks (COFs) are emerging as promising electrode materials due to their high surface area, tunable porosity, and design flexibility. However, their practical use in energy storage remains limited by their poor stability and electrochemical performance. Here, we report a nitrogen-rich COF, synthesized via an irreversible aromatic nucleophilic substitution between hexaazatriphenylenehexacarbonitrile and 3,3′-diaminobenzidine (HAT-DAB COF), forming stable – C═N– and −C–N– linkages. The framework integrates redox-active phenazine and arylamine units, offering a porous, crystalline, and nitrogen-rich architecture. Structural and morphological analyses confirm its robust and porous nature. As a bifunctional electrode, HAT-DAB COF shows excellent performance in lithium-ion batteries, with a specific capacity of 265 mAh/g, an energy density of ∼607 Wh/kg, and ∼98% Coulombic efficiency over hundreds of cycles. As a supercapacitor, it delivers 110.5 mF/cm² at 1 mV/s, with ∼95% capacitance retention and 100% Coulombic efficiency over 8000 cycles. Capacitance arises from a synergy of electric double-layer and redox (Faradaic) processes, with the diffusive component retained even at high scan rates, indicating strong pseudocapacitor behavior. This work demonstrates the value of irreversible linkages and rational redox-active design in achieving durable, high-performance COFs for next-generation energy storage applications.