High specific capacitance and high energy density supercapacitor electrodes enabled by porous carbon with multilevel pores and self-doped heteroatoms derived from Chinese date

Supercapacitors are attracting us for having advantages of fast charging and discharging, fine power density and great stability, however they are suffered from lower energy density, and high capacitance materials are the main point for fabrication of high energy density electrode materials. We present here a novel porous carbon derived from a high yield biomass Chinese date using a simple pre-carbonization process combined with KOH activation. The porous carbon prepared under the optimized conditions mainly composed of micropores and a certain number of mesopores, and its surface is covered with irregular pits, together with 18.13 at.% and 0.57 at. % self-doped O and N. The mesopores are conducive to the rapid transfer and diffusion of electrolyte ions; while the existence of micropores and irregular pits contribute to the large specific surface areas for ions to accommodate, and the participation of heteroatoms especially O 1 s, promote the wettability of electrolyte to electrode materials. It is just because of a combination of these advantage factors together, thus the electrodes based on this material generated an ultrahigh specific capacitance of 518 F/g at 0.5 A/g, with excellent rate performance of 40 F/g at 70 A/g. Notably, symmetric supercapacitors based on this material exhibited energy density of 18.5 Wh kg(-1) at a power density of 373.8 W kg(-1) in the aqueous electrolyte Na2SO4, and a high specific energy density of 51.3 Wh kg(-1) was achieved at a high power density of 767.8 W kg(-1) in the organic electrolyte Et4NBF4. These excellent results verified the potential of Chinese date derived porous carbon for high performance supercapacitors, and due to the advantages of abundant, renewable and inexpensive raw material, and eco-friendliness simplicity preparation process, it is practical to industrialization this material in the near future for scale-up production of high energy supercapacitors.