Fabrication and electrochemical capacitance of hierarchical graphene/polyaniline/carbon nanotube ternary composite film

A film composed of graphene (GN) sheets, polyaniline (PANI) and carbon nanotubes (CNTs) has been fabricated by reducing a graphite oxide (GO)/PANI/CNT precursor prepared by flow-directed assembly from a complex dispersion of GO and PANI/CNT, followed by reoxidation and redoping of the reduced PANI in the composite to restore the conducting PANI structure. Scanning electron microscope images indicate that the ternary composite film is a layered structure with coaxial PANI/CNT nanocables uniformly sandwiched between the GN sheets. Such novel hierarchical structure with high electrical conductivity perfectly facilitates contact between electrolyte ions and PANI for faradaic energy storage and efficiently utilizes the double-layer capacitance at the electrode–electrolyte interfaces. The specific capacitance of the GN/PANI/CNT estimated by galvanostatic charge/discharge measurement is 569 F g−1 (or 188 F cm−3 for volumetric capacitance) at a current density of 0.1 A g−1. In addition, the GN/PANI/CNT exhibits good rate capability (60% capacity retention at 10 A g−1) and superior cycling stability (4% fade after 5000 continuous charge/discharge cycles).

A hierarchical film with coaxial polyaniline/carbon nanotube (PANI/CNT) nanocables uniformly sandwiched between graphene (GN) sheets was prepared by filtration of the complex dispersion of graphite oxide (GO) and PANI/CNT.Figure optionsDownload as PowerPoint slideHighlights
► A film composed of GN sheets, PANI and CNTs was fabricated.
► The coaxial PANI/CNT nanocables uniformly sandwiched between the GN sheets.
► The unique structure facilitates contact between electrolyte and electrode materials.
► Each component provides unique function to achieve superior electrochemical properties.