Polypyrrole coated carbon nanotubes for supercapacitors, prepared using indigo carmine as a dispersant and dopant

A conceptually new approach has been developed for the fabrication of polypyrrole (PPy) coated multiwalled carbon nanotubes (MWCNT), based on the use of indigo carmine (IC) dye as a dispersant for MWCNT and anionic dopant for PPy polymerization. The IC dye allowed efficient MWCNT dispersion and promoted coating formation by PPy polymerization on MWCNT. The PPy coated MWCNT were used for energy storage in electrochemical supercapacitors (ES). The use of PPy coated MWCNT allowed excellent electrochemical performance for high active mass loadings, required for commercial ES applications. The electrodes and devices showed high capacitance, good capacitance retention at high charge–discharge rates and good cycling stability. The record high capacitance achieved at high charge–discharge rates is promising for the development of high power ES.