期刊
APPLIED SURFACE SCIENCE
卷 563, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apsusc.2021.150303
关键词
Porous; Parallel; Vertical; N-rich; Free-standing
类别
资金
- National Natural Science Foundation of China [51572078, 51772086, 51872087, 51971089]
- Natural Science Foundation of Hunan Province [2018JJ2038]
- Major Science and Technology Program of Changsha [kq1804010]
The freeze-dried N-HRGO films fabricated by a freeze casting method exhibit excellent electrochemical performance due to their cross-coupled porous ion diffusion networks, abundant pore structures for promoting ion diffusion, and nitrogen sites enhancing specific capacitance, resulting in a high specific capacitance of 528 F g(-1) and a high energy density of 14.0 Wh kg(-1) with excellent cycle life (89.3% capacity retention after 5000 cycles at 2 A g(-1)) when assembled into a symmetrical supercapacitor.
Graphene films suffer from poor electrochemical performance due to the undesirable ion diffusion inside its deep area and only electrical double layer absorption mechanism. Here, we proposed a freeze casting method for fabricating the N-rich holey reduced graphene oxide films (Freeze-dried N-HRGO) bearing cross-coupled porous ion diffusion networks. The H2O2 etching and modified vacuum filtration process generate abundant pore structures inside films, which act as ion diffusion path for promoting electrochemical performance. In addition, the N sites serve as pseudocapacitance contributor to react with electrolyte ions, which greatly enhance the specific capacitance. As a result, the freeze-dried N-HRGO films show a high specific capacitance of 528 F g(-1) at a current density of 1 A g(-1). When assembled into symmetrical supercapacitor, it delivers a high energy density of 14.0 Wh kg(-1) and excellent cycle life (89.3% capacity retention after 5000 cycles at 2 A g(-1)).
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