High-Performance Asymmetric Supercapacitor Based on Graphene Hydrogel and Nanostructured MnO2

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• 作者：Hongcai Gao ; Fei Xiao ; Chi Bun Ching ; Hongwei Duan
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：May 23, 2012
• 年：2012
• 卷：4
• 期：5
• 页码：2801-2810
• 全文大小：637K
• 年卷期：v.4,no.5(May 23, 2012)
• ISSN：1944-8252

文摘

We have successfully fabricated an asymmetric supercapacitor with high energy and power densities using graphene hydrogel (GH) with 3D interconnected pores as the negative electrode and vertically aligned MnO₂ nanoplates on nickel foam (MnO₂-NF) as the positive electrode in a neutral aqueous Na₂SO₄ electrolyte. Because of the desirable porous structure, high specific capacitance and rate capability of GH and MnO₂-NF, complementary potential window of the two electrodes, and the elimination of polymer binders and conducting additives, the asymmetric supercapacitor can be cycled reversibly in a wide potential window of 0鈥?.0 V and exhibits an energy density of 23.2 Wh kg^鈥? with a power density of 1.0 kW kg^鈥?. Energy density of the asymmetric supercapacitor is significantly improved in comparison with those of symmetric supercapacitors based on GH (5.5 Wh kg^鈥?) and MnO₂-NF (6.7 Wh kg^鈥?). Even at a high power density of 10.0 kW kg^鈥?, the asymmetric supercapacitor can deliver a high energy density of 14.9 Wh kg^鈥?. The asymmetric supercapacitor also presents stable cycling performance with 83.4% capacitance retention after 5000 cycles.

Keywords:

graphene hydrogel; manganese oxide nanoplates; cathodic electrodeposition; asymmetric supercapacitor; energy storage