Design, synthesis and the electrochemical performance of MnO2/C@CNT as supercapacitor material

•Carbon-coated carbon nanotubes are designed and synthesized to prepare MnO2/C@CNT.•The sacrificial carbon in C@CNT endows it suitable for the higher loading of MnO2.•MnO2/C@CNT composite with high MnO2 loading presents superior specific capacitance.•MnO2/C@CNT composite shows excellent cyclic stability.

Carbon-coated carbon nanotubes (C@CNT) was designed, synthesized and used as conductive substrate for loading manganese dioxide to prepare MnO2/C@CNT composite. C@CNT with self-sacrificial carbon layer as protection is suitable for loading higher content of MnO2. The morphology and microstructure of the as-prepared MnO2/C@CNT composite with MnO2 loading up to 78 wt% were investigated by SEM and TEM. The electrochemical performance of MnO2/C@CNT was evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) method. With the protective carbon layer on the surface of CNTs, MnO2/C@CNT composite presents superior specific capacitance of 227 F/g with MnO2 loading up to 78 wt% at a current density of 0.2 A/g and good cyclic stability with 94% of its maximal specific capacitance maintained after 1000 CV scans.

Graphical abstractThe extra carbon layer in C@CNT protects CNTs from being destroyed or even cut off and thus CNTs can maintain its morphology and microstructure during MnO2 immobilization, and effectively reduce charge transfer resistance inside the composite. The specific capacitance of MnO2/C@CNT electrode with high MnO2 loading up to 78 wt% is much higher than that of the MnO2/CNT electrode with the same MnO2 loading.Figure optionsDownload full-size imageDownload as PowerPoint slide