Polypyrrole Hybrid Nanocomposite Electrode Materials with Outstanding Specific Capacitance

This paper discusses the results of our investigation of the effect of processing parameters on the electrochemical properties of poly(vinylidene fluoride) single-walled carbon nanotube sheets and PVDF-CNTs modified by solution cast polyimide coating, followed by electrodeposition of polypyrrole. The polyimide-coated single-wall carbon nanotube sheet–PI/SWCNTs composite consists of SWCNT and PVDF (9:1) wt.% and 0.1–1 wt.% polyimide. The processing temperature varied from 90 to 250 °C. SEM images validated the nanostructure, while EDX confirmed the material composition. EIS analysis showed that the composite electrode material processed at 90 °C and followed by electrodeposition of polypyrrole has the lowest bulk resistance (65.27 Ω), higher porosity (4.59%), and the highest specific capacitance (209.16 F/g), indicating superior ion transport and charge storage. Cyclic voltammetry and cyclic charge–discharge analyses revealed that the hybrid composite electrode processed at 90 °C achieved a specific capacitance of 655.34 F/g at a scan rate of 5 mV/s, demonstrating excellent cycling stability over 10 cycles at a current density of 0.5 A/g. In contrast, composite electrodes processed at 180 °C and 250 °C showed decreased performance due in part to structural densification and low porosity. These findings underscore the critical role of processing temperatures in optimizing the electrochemical properties of PI/SWCNT composites, advancing their potential for next-generation energy storage systems.