Microwave assisted cobalt incorporated covalent organic frameworks as cathode material for asymmetric supercapacitor device

Abstract

Nitrogen-rich covalent organic frameworks (COF) with crystallinity and porosity are finding applications in electrochemical energy storage applications. The present work aims at developing a microwave-assisted synthetic method for the synthesis of COF using benzene-1,3-diamine and terephthalaldehyde (BDT-COF) through imine bond. BDT-COF modification was through the incorporation of cobalt (BDT@Co-COF). The morphological, structural and electrochemical properties of BDT-COF and BDT@Co-COF were examined and compared. Enhanced electrochemical performance was observed in BDT@Co-COF with a specific capacitance of 445 F/g compared to BDT-COF (196 F/g) at 2 mV/s. The density functional theory (DFT) shows a decreased bandgap in BDT@Co-COF (1.12 eV) compared to BDT-COF (1.70 eV). Asymmetric supercapacitor device (ASD) was fabricated using BDT@Co-COF and BDT-COF as positive and negative electrodes, respectively. The specific capacitance of ASD is found to be 220 F/g at 2 mV/s. A coin-type cell, model CR 2016, was also fabricated using the above-mentioned electrodes and used to power two red LEDs in parallel with a 1.45 V turn-on voltage for 10 min. The good stability and results of device fabrication tells about the well-confined structural arrangement in BDT@Co-COF.