Polypyrrole nanofiber–carbon nanotube electrodes for supercapacitors with high mass loading obtained using an organic dye as a co-dispersant

Abstract

Polypyrrole (PPy) nanofibers and composites, containing PPy and multiwalled carbon nanotubes (MWCNTs), were used for the fabrication of electrodes of electrochemical supercapacitors (ES). It was found that cationic malachite green (MG) dye adsorbed on PPy and MWCNTs and allowed their efficient electrosteric dispersion in water. Sedimentation tests, electrophoretic deposition (EPD) experiments, Fourier transform infrared spectroscopy and UV-Vis spectroscopy data showed strong adsorption of MG on PPy and MWCNTs. The important finding was the possibility of efficient dispersion of PPy and MWCNTs using MG dye as a co-dispersant. The new approach allowed colloidal processing of individual materials and composites. This method is suitable for the cathodic EPD of electrically neutral PPy and MWCNTs. The ES electrodes with high material loading in the range of 10–30 mg cm⁻² were prepared from colloidal suspensions of PPy nanofibers and MWCNTs using Ni foam current collectors. The composite PPy–MWCNT electrodes, prepared using MG, showed superior electrochemical performance compared to pure PPy and composite electrodes prepared without MG. The composite PPy–MWCNT electrodes with high mass loadings showed excellent capacitance retention at high scan rates and over a wide range of frequencies, and excellent cycling stability. The highest capacitance of 4.62 F cm⁻² was obtained at a material loading of 30 mg cm⁻². The PPy nanofiber–MWCNT composites, prepared using MG as a dispersant, are promising electrodes for ES.