Layered polyaniline/graphene film from sandwich-structured polyaniline/graphene/polyaniline nanosheets for high-performance pseudosupercapacitors

Binder-free layered graphene/polyaniline composite film was prepared by an environmentally friendly and facile two-step route for the first time. Firstly, a sandwich-structured PANI/graphene/PANI nanosheet was prepared in situ from aqueous solution, followed an electrophoretic deposition process. By observations of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM), it conforms that the graphene sheet is uniformly covered by an ultralthin PANI film (3.7 nm). Raman spectra, Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) are jointly used to confirm strong π-π electron and hydrogen bond interaction in the nanosheets. The layered PANI/graphene composite film exhibits an excellent gravimetric capacitance of 384 F g^-1 at 0.5 A g^-1 which is much higher than many other hybrid supercapacitors reported to date. It maintains its capacity up to 84% over 1000 cycles at a current density of 2 A g^-1. This preparation method may provide a promising strategy for preparation of graphene-based composites with other conducting polymers and binder-free film electrodes.