Design and synthesis of graphene/activated carbon/polypyrrole flexible supercapacitor electrodes

A ternary composite of graphene/activated carbon/polypyrrole (GN/AC/PPy) used as an electrode active material for supercapacitors has been synthesized via vacuum filtration and anodic constant current deposition methods. The ACs sandwiched between GN sheets can be used as flexible substrates for PPy nanoparticles, and the microscopic morphologies and electrochemical performances of GN/AC/PPy electrodes were synthesized and designed through regulating different deposition current densities and deposition times. The GN/AC/PPy15-200 s electrode exhibits a maximum areal specific capacitance of 906 mF cm(-2) with a PPy loading mass of 2.75 mg cm(-2) (specific capacitance of 178 F g(-1)) at a current density of 0.5 mA cm(-2). Its capacitance retention still remained at 64.4% after 5000 charge-discharge cycles and 83.6% after 500 stretching-bending cycles at a current density of 3 mA cm(-2). The flexible, free-standing and binder-free GN/AC/PPy electrodes have a broad prospect in flexible energy storage devices.