Fabrication of dually N/S-doped carbon from biomass lignin: Porous architecture and high-rate performance as supercapacitor

The lignin amine (LA) was exploited to prepare dually N/S-doped carbon (NSC), which was endowed with intriguing porous structure by Fe3O4 template. N and S elements, originating from LA, are doped into the materials. NSC possesses diverse-scale 3D pores. The macropores are made by Fe3O4, which facilitate to produce meso and micro pores on their walls by KOH activation. The sample prepared at 700 °C (NSC-700) is found to have the largest specific surface area (1199 cm2 g−1) and specific capacity (241 F g−1 at current density of 1 A g−1). Its capacity is 260% as high as that of lignin amine carbon (LAC) prepared without adding Fe3O4. Excellent rate performance is unraveled because of possessing 82% specific capacity at 20 A g−1 and 27.2 Wh kg−1 energy density at 10000 W kg−1 power density. Moreover, the specific capacity maintains 95.0% after 3000 cycles, indicating good electrochemical stability. The good electrical performance of NSC-700 is attributed to its interesting electronic properties that are induced by special pore structure. Because of having merits such as high rate performance, long life, large specific capacity and low cost, our NSC is anticipated to be a promising capacitor as electrode material.