Anionic dopant–dispersants for synthesis of polypyrrole coated carbon nanotubes and fabrication of supercapacitor electrodes with high active mass loading

Abstract

A conceptually new approach has been developed for the fabrication of composite polypyrrole (PPy)–multiwalled carbon nanotube (MWCNT) electrodes for electrochemical supercapacitors (ESs). The approach is based on the use of pyrocatechol violet (PV), eriochrome cyanine R (ECR) and acid fuchsin (AF) dyes as dispersants for MWCNTs and dopants for PPy polymerization. Testing results showed excellent electrochemical performance of the composite electrodes at high active mass loadings. The composite electrodes showed superior capacitance retention at high scan rates, compared to pure PPy electrodes. The comparison of the experimental data for the ES electrodes, prepared using different dyes, provided insight into the influence of their structure and functional groups on the composite microstructure and electrochemical performance. The use of ECR as a dispersant for MWCNTs and dopants for PPy allowed the fabrication of PPy coated MWCNTs. The fabrication method is simple and suitable for mass production. This new finding opens up a new and promising strategy for the fabrication of efficient ES electrodes and devices. The PPy coated MWCNTs were used for the fabrication of electrodes with a specific capacitance of 2.430–4.798 F cm−2 in the scan rate range of 2–100 mV s−1 for active mass loading of 18 mg cm−2. The ES cells showed high capacitance at different charge discharge rates and good cycling stability. The ES cells and modules showed promising performance for practical applications.