Reduced graphene oxide/carbon nanoparticles (RGO/CNs) composite films with good flexibility and high mechanical strength were prepared via a facile hydrothermal process of the beta-cyclodextrin modified graphene oxide (beta-CD/GO) hydrogel in presence of ascorbic acid (vitamin C), in which the GO was reduced into reduced graphene oxide (RGO) and beta-CD converted into carbon nanoparticles (CNs). The resulted CNs could enlarge the interlayer distance of graphene sheets not only to prevent their agglomeration, but also to improve the transfer speed of the electrolyte ions throughout the film electrodes during the charge/discharge process. The flexible and robust RGO/CNs composite films were then used as highly conductive supports for the electrodeposition of polyaniline (PANI) to further improve the electrochemical performance. As flexible and robust paper-like electrodes, the reduced graphene oxide/carbon nanoparticles/polyaniline (RGO/CNs/PANI) composite films exhibited high electrochemical activity, such as high specific capacitance of 787.3 F/g at the current density of 1 A/g and 564.0 F/g at the current density of 10 A/g, as well as excellent cyclic stability. The results demonstrated the significant potential application of the proposed RGO/CNs/PANI composite films as binder-free and free-standing electrodes for high-performance flexible energy storage devices. (c) 2017 Elsevier Ltd. All rights reserved.