The incorporation of spacers between graphene sheets has been investigated as an effective method to improve the electrochemical performance of graphene papers (GPs) for supercapacitors. Here, we report the design of free-standing GP@NiO and GP@Ni hybrid GPs in which NiO nanoclusters and Ni nanoparticles are encapsulated into graphene sheets through electrostatic assembly and subsequent vacuum filtration. The encapsulated NiO nanoclusters and Ni nanoparticles can mitigate the restacking of graphene sheets, providing sufficient spaces for high-speed ion diffusion and electron transport. In addition, the spacers strongly bind to graphene sheets, which can efficiently improve the electrochemical stability. Therefore, at a current density of 0.5 A g−1, the GP@NiO and GP@Ni electrodes exhibit higher specific capacitances of 306.9 and 246.1 F g−1 than the GP electrode (185.7 F g−1). The GP@NiO and GP@Ni electrodes exhibit capacitance retention of 98.7 % and 95.6 % after 10000 cycles, demonstrating an outstanding cycling stability. Additionally, the GP@NiO∥GP@Ni delivers excellent cycling stability (93.7 % after 10 000 cycles) and high energy density. These free-standing encapsulated hybrid GPs have great potential as electrode for high-performance supercapacitors.
Bibliographical noteFunding Information:
The work was supported by the National Natural Science Foundation of China (No. 21576138, 51572127), China-Israel Cooperative Program (2016YFE0129900), Program for NCET-12-0629, PhD Program Foundation of Ministry of Education of China (No.20133219110018), Natural Science Foundation of Jiangsu Province (BK20160828), Postdoctoral Foundation (1501016B), Six Major Talent Summit (XNY-011), and PAPD of Jiangsu Province, and the program for Science and Technology Innovative Research Team in Universities of Jiangsu Province, China, and Postgraduate Research & Practice Innovation Program of Jiangsu Province. We also thank Dr. Huaping Bai and Dr. Wanying Tang for the XRD and Raman data collection, at Analysis and Test Center Nanjing University of Science and Technology, and Dr. Sadaf Mu-tahir for refining the language.
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- cycle life
- free standing
- graphene paper