Ultrathin Manganese Dioxide Nanosheets Grown on Mesoporous Carbon Hollow Spheres for High Performance Asymmetrical Supercapacitors

Designing and fabricating the electrochemical active materials with outstanding electrochemical performance is crucial for supercapacitors in applications of energy storage devices. In this study, a structure of ultrathin manganese dioxide (MnO 2 ) nanosheets deposited on the surface of mesoporous carbon hollow spheres (MCHSs) is designed and fabricated through a simple method. MCHSs are served as both substrate materials for growth of MnO 2 nanosheets and electrical conductive layer for improving the poor electrical conductivity of MnO 2, thus obtaining MCHS/MnO 2 with good electrochemical performance. What’s more, the synergy of pseudocapacitance and electrical double-layer capacitance (EDLC) in asymmetrical configuration plays a crucial role in enhancing energy density of assembled supercapacitors. The obtained results exhibit that asymmetrical MCHS/MnO 2 //MCHS supercapacitor displays large specific capacitance (116.4 F/g at 0.1 A/g) and superior cycling stability (90.3% of capacitance retention after 6000 cycles), and delivers high energy density of 64.6 Wh/kg at power density of 100 W/kg. It has been demonstrated that assembled supercapacitor could be used as a small power supply to light a red LED. This study may provide a feasible method in energy storage applications.