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Design and Synthesis of N‑Doped Carbon Skeleton Assembled by Carbon Nanotubes and Graphene as a High-Performance Electrode Material for Supercapacitors

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journal contribution
posted on 2021-08-03, 13:34 authored by Fan He, Kanshe Li, Shaoling Cong, Hua Yuan, Xiaoqin Wang, Bohua Wu, Runlan Zhang, Jia Chu, Ming Gong, Shanxin Xiong, Yan Wu, Anning Zhou
Current, there is an urgent demand for electrode materials with superior electrochemical performances for the development of supercapacitors. A nitrogen-doped carbon skeleton (NCS) assembled by carbon nanotubes and graphene layers is designed and synthesized utilizing a layer-shaped humate-based zeolitic imidazolate framework (ZIF) (HA-CoFe-ZIF) as a template in this work. The synthesized NCS is mainly composed of graphitized carbon with a few hydroxyl groups on its surface, synchronously doped by 9.5 at % nitrogen in the state of pyridinic N and pyrrolic N. The rich mesoporous structure entitles it to a high Brunauer–Emmett–Teller (BET) specific surface area of 427 m2 g–1 and suitable BET average pore diameter of 3.14 nm. The NCS has a high capacity of 324 F g–1 at 1 A g–1, good rate capability (capacitance retention of 71% from 5 to 100 A g–1), and excellent cycling stability (capacitance retention of 96 and 87% after 5000 and 10 000 cycles, respectively). The fabricated NCS//AC asymmetric supercapacitor also exhibits a high capacity of 93 F g–1 at 1 A g–1, large energy density of 10.3 Wh kg–1 at 331 W kg–1, and good cycling performance (capacitance retention of 88% after 5000 cycles). Our elaborately designed NCS materials exhibit multiple structural advantages including rich mesoporous structure, various graphitic carbon, and high-dosage nitrogen doping, resulting in high capacitance performances. This humate-based metal–organic framework (MOF)-derived strategy provides a good idea for the synthesis of high-performance carbon skeleton materials applied to energy storage.