石墨烯-二氧化锰-导电层包覆-超电容Enhancing the Supercapacitor Performance of Graphene-MnO2.pdf

LETTER /NanoLett Enhancing the Supercapacitor Performance of Graphene/MnO2 Nanostructured Electrodes by Conductive Wrapping † ‡ § ‡ † ‡ ,‡ Guihua Yu, Liangbing Hu, Nian Liu, Huiliang Wang, Michael Vosgueritchian, Yuan Yang, Yi Cui,* and Zhenan Bao*,† †Department of Chemical Engineering, ‡Department of Materials Science and Engineering, and §Department of Chemistry, Stanford University, Stanford, California 94305, United States. S Supporting Information b ABSTRACT: MnO2 is considered one of the most promising pseudocapactive materials for high-performance supercapacitors given its high theoretical specific capacitance, low-cost, environmental benignity, and natural abundance. However, MnO2 electrodes often suffer from poor electronic and ionic conductivities, resulting in their limited performance in power density and cycling. Here we developed a “conductive wrapping” method to greatly improve the supercapacitor performance of graphene/MnO2-based nano- structured electrodes. By three-dimensional (3D) conductive wrapping of graphene/MnO2 nanostructures with carbon nanotubes or conducting polymer, specific capacitance of the electrodes (considering total mass of active materials) has substantially increased by ∼20% and ∼45%, respectively, with values as high as ∼380 F/g achieved. Moreover, these ternary composite electrodes have also exhibited excellent cycling performance with 95% capacitance retention over 3000 cycles. This 3D conductive wrapping appr