Covalent OrganicFramework-Derived Highly DefectiveCarbon-Integrated Polymer Composite Electrode for Supercapacitor Applications

Heteroatom-doped porous carbons are attractive electrode materials for supercapacitors due to their high specific capacitance and desirable surface properties. Here, we report a porous carbon (PI-COF-700) derived from a covalent organic framework (COF) that is rich in nitrogen species with an appreciable yield. The polyimide COF (PI-COF) was synthesized through the condensation reaction of 1,3,5-tris(4-aminophenyl) benzene (TAPB) and pyromellitic dianhydride (PMDA) under solvothermal conditions. The amorphous defective carbon nature and variation in functional groups of pyrolyzed PI-COF-700 were studied through physicochemical characterizations. In addition, the porous carbon presents a large surface area of 1080 m² g^–1 and a high micropore distribution ratio, which was observed from nitrogen adsorption/desorption isotherm measurement. Later, we developed a strategy of compositing PI-COF-700 with polyaniline (PANI) and poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) as an electrode material for supercapacitor application. The modified composite material exhibited a high specific capacitance value of 729.17 Fg^–1 at an applied current density of 2 Ag^–1, surpassing many of the previously reported supercapacitors based on organic framework-derived porous carbon composite systems. In addition, PANI/PEDOT/PSS@PI-COF-700 showed a capacitance retention close to ∼92.2% after 1000 cycles at an applied current density of 20 Ag^–1. An aqueous electrolyte-based symmetric supercapacitor electrode system constructed with this material demonstrated a specific capacitance of ∼182 Fg^–1 at 0.2 Ag^–1 and 89.81% retention after 10,000 cycles at 30 Ag^–1.