Rose-derived 3D carbon nanosheets for high cyclability and extended voltage supercapacitors

Biomass based porous carbon has been deemed to the most prospective electrode materials for high performance supercapacitors owing to its diversity and reproducibility. Herein, a three-dimensional (3D) porous structure consisting of interconnected carbon nanosheets were synthesized by withered rose through a convenient and efficient carbonization-activation method. This rose-derived active carbon nanosheets (RAC) display a high specific surface area (1911 m² g⁻¹) and a moderate bulk density (0.55 g cm⁻³). RAC-based supercapacitor electrode exhibits a remarkable cycling stability of 99% capacitance retention after 25000 cycles even at a high specific capacitance of 208 F g⁻¹. More importantly, its symmetric supercapacitor (SSC) owns an extended voltage window of 2.1 V and an excellent electrochemical stability (92% capacitance retention after 10000 cycles).