Covalent-Organic Framework Based Composite Materials for Supercapacitor Applications

Abstract

Covalent organic frameworks (COFs) are crystalline, porous materials formed by the covalent bonding of two monomers/ligands to create extended π-conjugated networks. Due to their high crystallinity, adjustable porosity, and structural tunability, COFs are promising for energy storage. However, the poor electrical conductivity of COFs is the biggest challenge for their electrochemical performance. To address this issue, combining COFs with conductive polymers through strong interactions can be an effective method to improve their electrochemical properties. This study introduces a method for embedding a COF with polyaniline (PANI) through in situ oxidative polymerisation to create a COF/PANI composite. Additionally, we compare the in-situ composite with a mechanically ground mixture (COF-PANI) to highlight the importance of in situ formation interactions. The structure of the hybrid was characterised by powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy, confirming its structural stability and the chemical bonding between components. The in situ-synthesised COF/PANI exhibits a conductivity nearly 10 times higher, reaching 11.5 S/m, compared to mechanically ground COF-PANI, which has a conductivity of 1.2 S/m. The COF/PANI composite delivers a high specific capacitance of 355±5 F/g at an applied current of 0.25 mA, significantly outperforming both the mechanically ground COF-PANI mixture and the pristine COFs. These performance enhancements are likely due to the strong synergistic effects of the conductive polymer network and the porous COF framework, which collectively promote efficient charge transport and ion diffusion. Hence, this chemically integrated architecture provides a versatile strategy for coupling COFs with conductive polymers, thereby enabling the rational design of high performance composite materials for advanced energy storage applications.