▎ 摘　　要

Binder-free electrode based on reduced graphene oxide (rGO) is attracting attention for electrochemical capacitors. Here the binder-free electrodes have been fabricated by activating the composite films of GO and carbonized cornstalk-cores. In the composites, the rGO sheets are found to be tightly adhered to the activated bio-carbon which is intercalated between the rGO sheets to prevent them from stacking. Moreover, the influences of the mass ratios of GO to bio-carbon on the electrochemical performance have been systematically investigated. The optimal binder-free electrode (rGO/ACCS(1/1)) prepared from the composite films with 1:1 mass ratio of GO to bio-carbon exhibits a specific capacitance as high as 278 F g(-1) at scan rate of 1 mV s(-1) and shows excellent stability in 6 M KOH electrolyte. Furthermore, the optimal electrode can retain 47.8% of the initial specific capacitance even at current density of 100 A g(-1), indicating a fast charge-discharge capability. This work provides a simple method to prepare binder-free composite electrodes by introducing renewable and inexpensive biomass based carbon into activated rGO films.