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.
Peng Song,Congcong Li,Ningmiao Zhao,Zhenyuan Ji,Linzhi Zhai,Xiaoping Shen,Qi Liu
Carbon nanosheets with heteroatom doping and well-developed porosity exhibit broad application foreground for Zn-ion hybrid supercapacitors (ZHSCs), but the simple and controllable preparation is still of great challenge. In this study, by using LiCl-KCl as in-built templates, histidine as carbon and nitrogen sources, and KNO 3 , K 2 SO 4 , KOH or Na 2 S 2 O 3 as active agent, a series of N and N S doped porous carbon nanosheets are developed. Results indicate that, with the activator introduction, pore structures of the carbonized products are notably boosted, showing an astounding 30–244 % increase in BET specific surface area, and meanwhile, heteroatom with a content of ca. 12 % can be doped into the resultant carbon skeletons. Specifically, the NSPCN-800 (activated by Na 2 S 2 O 3 ) with a large specific surface area of 1297 m 2 /g, a hierarchically porous structure composed of abundant micropores and mesopores, and a suitable heteroatom content (N: 11.9 wt%; S: 0.6 wt%) presents an impressive energy storage behavior as cathode for ZHSCs, including a specific capacitance of 165.8F/g, a specific capacity of 95.2 mAh/g, an energy density of 59.0 Wh kg −1 and a cyclic stability with a 82.6 % capacity retention after 5000 cycles. These performance parameters surpass numerous reported ZHSCs, making NSPCN-800 a very promising cathode for practical use.
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