Nitrogen Abundant Hexaazatriphenylene-diaminobenzidine Covalent: Organic Framework as Promising Cathode Material in Lithium-ion Battery

In recent years, covalent organic frameworks (COFs) have emerged as promising materials because of their porosity, crystallinity, tunability and composition of lightweight elements. Conventionally, COFs have been mostly synthesized by reversible reactions to impart crystallinity. However, irreversible aromatic nucleophilic substitution reactions can lead to more stable materials which are much more relevant to electrochemical applications. Embedding nitrogen atoms in the rigid carbon framework in the form of phenazine and secondary arylamine moieties provides redox-active sites to the material which has been shown to provide impressive performance as cathode material in lithium-ion batteries. Herein, we report a nitrogen-rich, hexaazatriphenylene-diaminobenzidine based COF through -C-N- linkages synthesized via irreversible aromatic nucleophilic reactions. Due to its diverse structural features, our COF serves as a highly viable electrode material, demonstrating excellent stability and recyclability in Li-ion batteries. Our COF achieves an impressive capacity of 265 mAh/g at a current density of 0.02 A/g, with a remarkable energy density of 607 Wh/kg. Furthermore, it retains a high Coulombic efficiency of ~98% throughout the charge-discharge process even after several hundred cycles.