N, O-codoped hierarchical carbon nanofiber mats prepared by in-situ KCl assisted electrospinning towards boosted areal capacitance in electrochemical capacitors

Functionalization and pore engineering are two effective approaches to enhance the electrochemical performance via augmenting the surface area utilization of carbon nanofiber (CNF) mats. Compared with heteroatom-doping, designing the suitable porous structure under a mild and controlled thermal process remains a formidable task. In this work, porous N, O-codoped CNF mats were prepared by using coal tar pitch/polyacrylonitrile (CTP/PAN) precursor and KCl salt template. Notably, the KCl can not only serve as porogen, but also act as a heat scavenger during the heat treatment process to avoid local temperature overheating, which is conducive to the uniform dissipation of organic small molecules, leading to improved ion-accessible area. The sample treated with 0.5 g KCl shows high areal capacitance and excellent rate performance in both 6 M KOH and 2 M ZnSO 4 electrolyte. Furthermore, the assembled Zn-ion capacitor exhibits a high energy density of 505.93 μW h m −2 at the power density of 496.28 μW m −2 , and maintained a maximum power density of 45.94 mW m −2 while retaining an energy density of 313.91 μW h m −2 . The present method is efficient, and cost-effective, and can be extented to the preparation of other electrode materials with superior electrochemical performance.