A binder-free electrode based on spherical polypyrrole (PPy) nanoparticles growing on the reduced graphene oxide (RGO)-coated carbon cloth (CC) was fabricated and demonstrated its implementation for flexible all-solid-state supercapacitors (FSSCs). Graphene oxide (GO) was first coated on CC substrate by a facile dip-coating method, and then spherical PPy nanoparticles were grown on its surface and interior. The GO-coated CC provided an interconnected network for the growth of spherical PPy nanoparticles due to the good interfacial compatibility between GO and PPy. And the GO in the composite electrode was then reduced to obtain CC@RGO/PPy flexible electrodes. The as-prepared CC@RGO/PPy FSSCs exhibited better electrochemical performance than CC/PPy FSSCs. Furthermore, the flexible electrodes with uniform microstructures, large specific surface area and fine pore structure could be optimized and obtained through a dropwise adding method. The optimized CC@RGO/PPy FSSCs exhibited enhanced areal capacitance of 985 mF cm(-2) at 2 mA cm(-2), energy density of 1.10 mWh cm(-3) at the power density of 0.01 W cm(-3) and good flexibility under bending condition. And the excellent electrochemical performance could be ascribed to the ingenious design and optimized structure of electrodes. The highperformance FSSCs have potential and promising application in the new generation of electronic devices. (C) 2017 Elsevier B.V. All rights reserved.