Carbon@MnO2 core–shell nanospheres for flexible high-performance supercapacitor electrode materials

• Carbon@MnO2 core–shell hybrid nanospheres are developed for supercapacitor electrode materials.
• The synthesis process is a quite facile and low-cost.
• The hybrid nanospheres exhibit good electrochemical performance.
• The powdery composite can be used for flexible supercapacitors.

We have developed a low-cost and facile preparation of powdery carbon@MnO2 core–shell hybrid nanospheres for supercapacitor electrode materials. The core carbon spheres serve as supporting template and electronically conductive material for the nanostructured MnO2 shell, which is benefit for the improve of the capacitive performance. By simply controlling the reaction time, various nanostructure MnO2 shells with different morphologies and crystalline structures are obtained. Typically, the hybrid nanospheres with flower-like birnessite-type MnO2 shells exhibit a highest capacitance of 252 F g−1 (based on the mass of MnO2) at the scan rate of 2 mV s−1, an excellent rate performance with a specific capacitance of 175 F g−1 at 100 mV s−1 and a good cycle ability with 74% retention after 2000 cycles at 5 A g−1. The results indicate that this kind of hybrid core–shell carbon@MnO2 nanospheres have great potential in the future practical applications.

Carbon@MnO2 core–shell hybrid nanospheres have been synthesized by a facile redox reaction between KMnO4 and carbon. By controlling the reaction time, various MnO2 shells with different morphologies and crystalline structures are obtained. Among these composites, the C@MnO2-20 exhibits the best electrochemical performances for supercapacitor electrode.Figure optionsDownload as PowerPoint slide