Electropolymerization and characterization of fast charge-discharge PPy/F-SWNTs composite materials

Fast charge-discharge composite materials of conducting polypyrrole and functionalized single-walled carbon nanotubes doped with p-toluenesulfonate (PPy-TOS/F-SWNTs) were prepared by galvanostatic electrochemical polymerization. Scanning Electron Microscope (SEM) images showed that the composite had a nano-rod structure with a diameter of about 70 nm. Nitrogen adsorption-desorption experinents were used to characterize the specific surface area (BET) (up to 12.64 m2·g-1) and pore sizes of the composite. Electrochemical properties of the composites were studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GC) measurements. The specific capacitance of this composite is about 211 F·g-1 (energy density: 18.7 Wh·kg-1) at a current density of 2.5 A·g-1, and 141.8 F·g-1 (energy density: 12.6 Wh·kg-1) at large current density of 80 A·g-1. The composite had excellent cyclability with a capacity retention of about 95.2% after 10000 cycles at a current density of 10 A·g-1. All these results indicate that this new composite material has a very rapidly charge-discharge ability.