Pulsed electrochemical fabrication of graphene/polypyrrole composite gel films for high performance and flexible supercapacitors

Uniform deposition of thin conducting polymer coatings on the surface of a porous structure is in demand for the fabrication of high performance electrodes for energy storage. A facile pulsed electrochemical method is developed in the present work for the preparation of porous reduced graphene oxide/polypyrrole (rGO/PPy) composite films. This method combines blade casting of graphene oxide (GO) gel and pulsed electrochemical technic which not only simplifies the precursor electrolyte but also preserves the porous structure of GO gel. The optimized rGO/PPy composite film exhibits a well-defined porous structure, leading to superior electrochemical performance with a high specific capacitance of 414 F g(-1) at 0.2 mA cm(-2). This optimized rGO/PPy electrode further demonstrates a large areal capacitance (419 mF cm(-2)) and excellent rate performance (180 mF cm(-2) even at 40 mA cm(-2) with 43% retention). Two-electrode aqueous supercapacitor based on the optimized rGO/PPy gel film electrodes exhibits excellent cycling stability with 95.7% capacitance retention after 10,000 cycles. Moreover, the as-fabricated flexible supercapacitor based on the rGO/PPy film electrodes on carbon cloth substrate shows good flexibility with 100% capacitance retention after 100 bending cycles. The present work provides a feasible electrochemical route for the fabrication of rGO based composite film electrodes. (C) 2020 Elsevier Ltd. All rights reserved.