Facile 3D Nitrogen‐Doped Hierarchical Porous Carbon for High‐Performance Supercapacitors

A novel activated nitrogen-doped hierarchically porous carbon (ANPC) material has been synthesized using polyurethane foam as the supporting template, phenolic resin with a high carbonization ratio, and low-cost ammonium polyphosphate as the carbon and nitrogen sources, respectively. The preparation process comprises curing and carbonization combined with KOH activation. Despite the simplicity of the process, the obtained ANPC-4 exhibits a high specific surface area (1452 m(2) g(-1)), a well-developed specific pore volume (0.799 cm(3) g(-1)), moderate mesoporous content (32.7%), good electrolyte ions transport property, and appropriate nitrogen dopant content. When used as a material for fabricating supercapacitor electrodes, the ANPC-4 exhibits a significantly high capacitance value of 356 F g(-1) at 0.2 A g(-1) in a 6 M KOH electrolyte with outstanding rate performance. In addition, the symmetrical capacitors assembled by ANPC-4 have good specific capacitance (175 F g(-1) at 0.2 A g(-1)), high energy density up to 24.3 Wh kg(-1), and good cycling stability (94.5% capacitance retention after 10 000 cycles of testing).