N-doped porous carbons with increased yield and hierarchical pore structures for supercapacitors derived from an N-containing phenyl-riched copolymer

N-doped porous carbon-based materials (NPCMs) with hierarchical pore structures have been considered to be a suitable alternative to meet the ever-increasing demands for supercapacitors; however, the universally low yield of the NPCMs has restricted their practical applications. Herein, a series of NPCMs with hierarchical pore structures are synthesized with significantly increased yields through the carbonization of the copolymer made from 2,4,6-tris(chloromethyl)mesitylene and p-phenylenediamine. The development of the hierarchical pore structures and the N content of the NPCMs show opposite dependences on the increasing carbonization temperature. The NPCM exhibits the best capacitive ability only if the sufficiently developed hierarchical structures and moderate N content are achieved simultaneously. Therefore, NPCM-600 that is carbonized at 600 °C with an excellent yield of 53.6% (wt.), large specific surface area of 1778 m² g⁻¹, and N content of 4.13% (wt.) yields an ideal specific capacitance of 298 F g⁻¹ at the current density of 1 A g⁻¹ and a perfect cycling stability of the capacitance after 10,000 cycles at 10 A g⁻¹. The yield of the NPCM-600 is considerably higher than those for many other recently reported NPCMs. NPCM-600 also shows better capacitance than those of the other reported NPCMs, such as NOPC-bis-CN-3 (167 F g⁻¹) and CHCPB-K-600 (260 F g⁻¹).