Vertical Graphene@Carbon Fiber Covered with MnO₂ Flower-Like Nanostructures via Electrodeposition for High-Performance Supercapacitors.

The research systematically investigated the synthesis process and electrochemical performances of willowy integrated MnO₂/vertical graphene@carbon fiber (MnO₂/GCF) hybrids. With the highly willowy carbon fiber as skeleton, graphene and ultrathin MnO₂ nanosheets were grown via plasma enhanced chemical vapor deposition and cyclic voltammetric electrodeposition, in sequence respectively. The triaxial (3D) MnO₂/GCF networks demonstrated highly multihole structure. Ascribed to the good performance, MnO₂/GCF nanomaterials can be manufactured into supercapacitor electrodes straightway and doesn't use binder as well as conductive agents. In addition, the electrochemical performance of the MnO₂ nanoflakes increased not only because of the fast ion diffusion among the triaxial porous vertical graphene@carbon fiber framework but also excellent contact of its' interfaces and outstanding synergistic effect between each other. In this paper, the capacitance performance of MnO₂/GCF composite samples with different electrodeposition time of MnO₂ nanoflakes was investigated. The results showed that the MnO₂/GCF composite with electrodeposition time of 64 min (MnO₂/GCF-64) had the highest specific capacitance of 565.23 F g when the current density was 1 A g and excellent cycling stability (82% specific capacitance retention after 2000 cycles). The willowy vertical graphene@carbon fiber substrate covered with flower-like MnO₂ nanosheets can serve as high performance supercapacitor, which enjoys a promising application prospect.