Polypyrrole coated carbon nanotubes for supercapacitor devices with enhanced electrochemical performance

Abstract

Polypyrrole (PPy) electrodes for electrochemical supercapacitors (ES) are prepared using amaranth as a new redox-active anionic dopant for chemical polymerization of PPy. The use of amaranth allows excellent electrochemical performance of electrodes with high mass loading and high PPy to current collector mass ratio. The specific capacitance of 4.2 F cm−2 is achieved at a scan rate of 2 mV s−1. The analysis of electrochemical testing results provides an insight into the influence of the chemical structure of amaranth on microstructure, electrochemical properties and cycling stability of PPy. New method is introduced for the fabrication of PPy coated multiwalled carbon nanotubes (MWCNT). The use of amaranth allows fine microstructure of PPy coatings formed on MWCNT, which are well dispersed in the presence of pyrocatechol violet dispersant. The use of PPy coated MWCNT allows significant improvement in capacitance retention at high charge–discharge rates, compared to pure PPy material, and good cycling stability of individual electrodes and ES cells. The ES cells, based on PPy show specific capacitance of 1.3–1.6 F cm−2 at discharge current densities of 1–33 mA cm−2.