Asymmetric Supercapacitors Based on Graphene/MnO2 Nanospheres and Graphene/MoO3 Nanosheets with High Energy Density |
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Authors: | Jian Chang Meihua Jin Fei Yao Tae Hyung Kim Viet Thong Le Hongyan Yue Fethullah Gunes Bing Li Arunabha Ghosh Sishen Xie Young Hee Lee |
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Affiliation: | 1. IBS Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), , Daejon, 305‐701 Republic of Korea;2. Department of Energy Science, Department of Physics, Sungkyunkwan University, , Suwon, 440‐746 Republic of Korea;3. National Center for Nanoscience and Technology, , Beijing, 100190 PR China;4. School of Materials Science and Engineering, Harbin University of Science and Technology, , Harbin, 150040 PR China;5. Department of Energy Science, Sungkyunkwan University, , Suwon, 440‐746 Korea;6. Institute of Physics, Chinese Academy of Sciences, , Beijing, 100190 PR China |
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Abstract: | Asymmetric supercapacitors with high energy density are fabricated using a self‐assembled reduced graphene oxide (RGO)/MnO2 (GrMnO2) composite as a positive electrode and a RGO/MoO3 (GrMoO3) composite as a negative electrode in safe aqueous Na2SO4 electrolyte. The operation voltage is maximized by choosing two metal oxides with the largest work function difference. Because of the synergistic effects of highly conductive graphene and highly pseudocapacitive metal oxides, the hybrid nanostructure electrodes exhibit better charge transport and cycling stability. The operation voltage is expanded to 2.0 V in spite of the use of aqueous electrolyte, revealing a high energy density of 42.6 Wh kg?1 at a power density of 276 W kg?1 and a maximum specific capacitance of 307 F g?1, consequently giving rise to an excellent Ragone plot. In addition, the GrMnO2//GrMoO3 supercapacitor exhibits improved capacitance with cycling up to 1000 cycles, which is explained by the development of micropore structures during the repetition of ion transfer. This strategy for the choice of metal oxides provides a promising route for next‐generation supercapacitors with high energy and high power densities. |
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Keywords: | graphene asymmetric supercapacitors metal oxides work functions |
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