KNO3-mediated synthesis of high-surface-area polyacrylonitrile-based carbon material for exceptional supercapacitors

Exploration of effective ways to highly porous carbon is a critical but remains challenging issue for high-performance supercapacitors. Here, we propose a new and facile strategy to synthesize polyacrylonitrile-based porous carbon (PPC) material. The as-prepared PPC not only possesses a well-defined hierarchical pore structure, but also exhibits the highest BET surface area of 3751 m(2) g(-1) and the largest pore volume of 2.48 cm(3) g(-1) among all the materials derived from polyacrylonitrile. The key to this preparation strategy is utilization of KNO3 as a mediator for pre-oxidation of polyacrylonitrile, which leads to construction of a fluffy and rigid semi-carbonized framework for the easy accessibility of activator KOH. Benefiting from the well-developed porosity, the PPC electrode exhibits an unusually high capacitance of 448 F g(-1) at 0.5 A g(-1) and an outstanding long-term stability of 96.5% capacitance retention after 10000 cycles in 1.0 V aqueous supercapacitors. Additionally, a remarkable energy density of 23.6 Wh kg(-1) can be delivered at a high out-put power density of 220 W kg(-1) in 1.8 V aqueous supercapacitors. These attractive electrochemical properties enable PPC to go far beyond many reported carbonaceous electrodes, which is expected to be as competitive candidate for high-performance supercapacitor electrode. (C) 2019 Elsevier Ltd. All rights reserved.