Nitrogen-doped porous carbon (NPC) was prepared by one-step carbonization and activation using phenolic resin as carbon source, polyurethane sponge as nitrogen source and carbon supporting framework, and KOH aqueous solution as activation pore-causing agent. The effects of nitrogen doping and different amounts of KOH on the structure and capacitance of NPC were studied. The results show that NPC-2.0 (The amount of KOH used in the raw material was 2.0 g) has high specific surface area (1 195 m2/g) and pore volume (0.788 cm3/g). In the three-electrode system, the specific capacitance of NPC-2.0 can reach 377 F/g at 0.2 A/g current density. The capacitance retention rate after 8 000 cycles is still 96.8%. In the two-electrode system, the energy density of the symmetrical capacitor assembled by NPC-2.0 can reach 6.05 W·h/kg while the power density is 125 W/kg, and the capacitor retention rate after 10 000 times of charging and discharging is 96.0%.NPC-2.0 obtained by one-step in-situ nitrogen doping shows good capacitive performance, and the preparation process is simple, which has broad research and application prospects.

one-step method; nitrogen doping; porous carbon; KOH; supercapacitors