High-performance hybrid capacitor based on a porous polypyrrole/reduced graphene oxide composite and a redox-active electrolyte

Aqueous redox-active electrolytes can provide a significant improvement in electric energy storage for electrochemical capacitors. Herein, we report a novel hybrid capacitor consisting of porous polypyrrole/reduced graphene oxide (PPy/rGO-HT) composite electrodes and an aqueous electrolyte with hydroquinone redox-active species. A hydrothermal-assisted synthesis of the PPy/rGO-HT composite allowed to obtain a porous polymer-graphene composite with a high specific surface area of 597 m2 g−1. In a three-electrode configuration with the redox-active electrolyte, PPy/rGO-HT exhibits better electrochemical performance in terms of specific capacity and cycling stability compared with that of pristine rGO. An assembled symmetric device achieves excellent long-term stability and a specific energy of 6.5 Wh kg−1, indicating the potential of hybrid systems for energy storage applications. [Display omitted] •PPy combined with GO under hydrothermal conditions yielded a porous composite.•The binary material achieved a high specific surface area of 597 m2 g−1.•The redox-active electrolyte greatly contributed to the total capacity of the system.•Symmetric hybrid device exhibited excellent long-life performance over 12 000 cycles.