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

Abstract We have developed a low-cost and facile preparation of powdery carbon@MnO 2 core–shell hybrid nanospheres for supercapacitor electrode materials. The core carbon spheres serve as supporting template and electronically conductive material for the nanostructured MnO 2 shell, which is benefit for the improve of the capacitive performance. By simply controlling the reaction time, various nanostructure MnO 2 shells with different morphologies and crystalline structures are obtained. Typically, the hybrid nanospheres with flower-like birnessite-type MnO 2 shells exhibit a highest capacitance of 252 F g −1 (based on the mass of MnO 2 ) 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@MnO 2 nanospheres have great potential in the future practical applications.