Fabrication of PANI/MWCNT supercapacitors based on a chitosan binder and aqueous electrolyte for enhanced energy storage

Abstract

In the mainstream renewable and sustainable nanotechnology, supercapacitors have emerged as critical energy conversion and storage systems. Carbon nanotubes (CNTs) are promising electrode materials in supercapacitors due to their excellent ability to conduct electricity and their high specific surface area. Due to its wide range of pseudocapacitive performance along with various oxidation states, polyaniline (PANI) has been widely used in energy storage applications as an electroactive material. In this study, the development of hybrid composite electrode materials containing multi-walled carbon nanotubes (MWCNTs) and conductive polyaniline (PANI) with different aniline/carbon ratios by in situ chemical oxidation polymerization is discussed. In the resulting PANI/MWCNT composites the CNTs are completely coated with PANI as concluded from scanning and transmission electron microscopy (SEM and TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and conductivity studies. The electrochemical performances of the electrodes produced with an eco-friendly chitosan binder were investigated with 0.5 M Na₂SO₄ aqueous electrolyte. Cyclic voltammograms (CV) and galvanostatic charge–discharge (GCD) curves of PANI/MWCNT composites show that the pseudo-capacitance of PANI improves the final electrochemical performance of the composites compared to that of pristine MWCNTs. While pure MWCNTs have a specific capacitance of 21.8 F g⁻¹ and energy density of 0.7 W h kg⁻¹, the PANI/MWCNT (30 : 1) composite exhibits a high specific capacitance of 300 F g⁻¹ and energy density of 9.8 W h kg⁻¹. However, the presence of CNTs stabilizes the cycling performance of the composite electrode materials.