Hierarchical porous biomass-derived carbon framework with ultrahigh surface area for outstanding capacitance supercapacitor

A porous carbon framework is successfully synthesized from lycium chinensis via a novel strategy using melamine matched with KOH as dual-activator. The biomass-derived carbon framework with hierarchical macro-/meso-/micro pores demonstrates an ultrahigh surface area of 3344 m2 g−1 and a sufficient total pore volume of 1.71 cm3 g−1. The porous carbon electrode with optimized structure presents an outstanding electrochemical performance. The specific capacitance reaches 520.0 F g−1 at 1 A g−1 and 291.0 F g−1 at 30 A g−1 with 96.8 % capacitance retention after 10 000 cycles at 30 A g−1. The energy density is also as high as 12.5 W h kg−1 for the electrode. The relationship between optimized structure and excellent performance of carbon materials is deeply explored. The superior electrochemical performance of carbon framework can be ascribed to its hierarchical porosity, ultrahigh surface area, sufficient total pore volume, proper graphitization degree and favorable heteroatom-doping, which will result in the fast ion diffusion, sufficient charge storage as well as the contributed pseudocapacitance. The work provides an effective guidance for synthesizing the superb porous biomass-derived carbon materials for supercapacitor with high performance.