N/O co-doped interlinked porous carbon nanoflakes derived from soybean stalk for high-performance supercapacitors

In this study, interlinked porous carbon nanoflakes (IPCNs), using soybean straw as precursor and urea as nitrogen source, were fabricated by a facile co-hydrothermal pretreatment, subsequent KOH activation procedure. The influence of the mass ratio of urea to soybean straw and activation temperature on the overall structure, pore size distribution and surface element composition of IPCNs was investigated. Unique pore distribution provides more active sites and interconnected ion transmission paths, which is beneficial for improving the electrochemical performance of IPCNs. The specific surface area of N1SSC-700 is as high as 2631 m(2) g(-1) with a total pore volume of 1.23 cm(3) g(-1), and the N and O doping amounts are 3.46% and 11.89%, respectively. The suitable heteroatoms doping content on IPCNs surface not only contribute to shortening the wetting time of electrolyte solution to electrode material, but also increasing pseudocapacitance. Therefore, N1SSC-700 possesses high specific capacitances of 325 F g(-1) for a three-electrode system and of 161 F g(-1) for a two-electrode system at 0.5 A g(-1) in 6 M KOH. Moreover, the energy density of N1SSC-700 is high up to 22.36 W h kg(-1) at a power density of 0.51 kW kg(-1). These results indicated that unique IPCNs derived from soybean straw are a promising material for supercapacitors.