Three-dimensional flexible carbon electrode for symmetrical supercapacitors

•3D porous AC with galore micro/macropores was fabricated.•The macropores facilitate the CNTs and rGO into the structure.•The composite with CNTs, rGO and AC shows good flexibility.•The assembled symmetrical capacitor delivers high capacitance and good cycling stability.

Three-dimensional (3D) porous active carbon (AC) is fabricated by pyrolysis, pre-carbonization, and alkali activation of the biomass of pomelo peels (PP). The PP-derived AC has abundant micro/meso/macropores boosting a large specific surface area of 1665 m2 g−1 and facilitating incorporation of the carbon nanotubes (CNTs) and reduced graphene oxide (rGO) into the materials. After mixing with CNTs and rGO, the hybrid carbon film with 80 wt% AC (AC/rGO/CNT) exhibits a large capacitance of 214 F g−1 at 1 A g−1, good rate capability, as well as excellent mechanical properties. The specific capacitance of the assembled symmetrical capacitor comprising the hybrid carbon film is 101.5 F g−1 at 1 A g−1 and in conjunction with the superior cycling stability, the high-performance flexible carbon-based supercapacitors (SCs) have large commercial potential.