Synthesis of Nitrogen‐Doped Microporous/Mesoporous Carbon with Enhanced Pseudocapacitive Behavior for High‐Performance Symmetrical Supercapacitors

• Published in: ChemElectroChem Vol. 7; no. 12; pp. 2592 - 2598
• Main Authors: Guo, Jia‐Kang, Liu, Jian, Kong, Ling‐Bin
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 17.06.2020
• Subjects: Capacitance; Carbon; Cycles; Electrode materials; Electrodes; Flux density; Heat treatment; Interpenetrating networks; micropores/mesopores; N-doping; Nitrogen; Phase separation; Polymers; pseudocapacitance; Pyrolysis; Sodium sulfate; Stability; Supercapacitors
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202000473

Hierarchical porous carbons are widely used as electrode materials for supercapacitors; however, promotion of the specific capacitance and energy density remains a challenge. Here, we design a N‐doped hierarchical microporous/mesoporous carbon (NMC) fabricated through the one‐step heat treatment of interpenetrating polymer networks. The pores are obtained by phase separation of the two network polymers with physical penetration and subsequent pyrolysis of the sacrificial polymers to shape the rich micropores/mesopores on the pore wall of a honeycomb‐like carbon skeleton formed from carbon precursors. In particular, the optimized NMC possesses an ultrahigh specific surface area of 1969.0 m2 g−1 and a pore volume of 1.092 cm3 g−1, as well as homogeneous distribution of elemental nitrogen. The NMC also exhibits a distinguished specific capacitance of 261.6 F g−1 at 0.5 A g−1 and an excellent cycling stability of 100 % after 10 000 cycles in 6 M KOH in a three‐electrode system. Impressively, in situ heteroatom doping of NMC effectively enhances the specific capacitance, and the proportion of pseudocapacitive performance can be as high as 25.4 % of the total capacitance. Symmetrical supercapacitors assembled with two protruding electrodes deliver a high energy density of 23.9 W h kg−1 at 225 W kg−1 and an outstanding cycling stability of 93 % after 10 000 cycles in 1 M Na2SO4. All of these features indicate that N‐doped microporous/mesoporous carbon is a promising electrode material for supercapacitors. Plenty of pore‐tential: Nitrogen‐doped hierarchical microporous/mesoporous carbon materials are successfully fabricated by high‐temperature pyrolysis of urea−formaldehyde‐based polymers. The as‐obtained carbon materials with tunable micropores/mesopores exhibit a high specific surface area of 1969 m2 g−1 and an outstanding specific capacitance of 261.6 F g−1 at 0.5 A g−1. The contribution of pseudocapacitance is up to 25.4 % and effectively improves their application in supercapacitors with 23.9 W h kg−1 at 225 W kg−1 in 1 M Na2SO4.