Three-dimensional flexible carbon electrode for symmetrical supercapacitors

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.