▎ 摘　　要

Intrinsically conducting polymers like polyaniline (PANI) demonstrate much higher specific capacitance than carbon based materials for the electrode active materials of supercapacitors, but the cycle-stability of PANI is rather poor. The reason may lie in the internal stress change of PANI due to the counter-anions intercalating/dissociating during doping and dedoping. Here we proposed a sandwich nanocomposite methodology where electroactive PANI was sandwiched between a conducting graphene layer and a multi-walled carbon nanotubes (MWCNTs) layer, i.e., PANI was first deposited on the surface of MWCNTs nanofibers via in situ copolymerization of aniline and p-phenylenediamine in the acidic dispersion of MWCNTs to fabricate the one-dimensional PANI/MWCNTs nanofibers, then the assembly between graphene oxide sheets and PANI/MWCNTs nanofibers was realized by electrostatic interactions, followed by a reduction of the graphene oxide to obtain the sandwich nanocomposites. The hybrids demonstrated superior electrochemical properties in comparison with the pristine PANI in a propylene carbonate/1M Et4N+center dot BF4- electrolyte. The specific capacitance of the hybrid composites was 259.4 F g(-1) at the current density of 0.5 A g(-1), and over 76.5% of the initial specific capacitance was retained over 2500 charging/discharging cycles, much better than that for pure PANI (only 38.9% retention).