Capacitive characteristics of nanocomposites of conducting polypyrrole and functionalized carbon nanotubes: pulse current synthesis and tailoring

Conducting polypyrrole (PPy) is an attractive material for supercapacitors with a high specific capacitance and environmental friendliness feature, but it suffers from the limited power density and short cycling life due to the low ionic mobility and mechanic stress resulting from ions in/out solid phase, respectively. Here, we present PPy–p-toluenesulfonate (TOS) and functionalized single-walled carbon nanotube (FSWNT) nanorod-like composites deposited by pulse current method in TOS and FSWNT dispersive solutions, with a diameter of less than 20 nm due to the improved FSWNT concentration near the polymerization interface during pulse-off time. The reduced ion diffusion length and the high diffusion coefficient of PPy–TOS synthesized by pulse current method lead to the nanocomposites with a high specific capacitance of 360 F g−1 at a current loading of 20 A g−1 and an ultrafast charging/discharging capability with a value of 280 F g−1 at even 0.1 s. Moreover, the fine nanostructure, which can accommodate the mechanical stress during charging/discharging process, significantly prolongs the cycling life of the nanocomposites, with its capacitance well maintained of 80 % after 100,000 continuous cycles at a current load of 400 A g−1. All of these enable the nanocomposites to be excellent active materials for high-performance supercapacitors.