Scalable construction of heteroatom-doped and hierarchical core–shell MnO2 nanoflakes on mesoporous carbon for high performance supercapacitor devices

Abstract

Highly ordered N,S-codoped mesoporous carbon (NSMC) is fabricated via a sacrificial template method followed by a facile doping reaction. Thanks to the uniform mesoporous channels, NSMC exhibits a high specific capacitance of 298 F g⁻¹. Moreover, deposition of MnO₂ nanosheets onto the mesoporous carbon channels is performed via a solvothermal reaction. By controlling the reaction time, various composites and the corresponding electrochemical performance are obtained. The maximum capacitance of MnO₂@mesoporous carbon (MnO₂@MC-30) is 310 F g⁻¹. An asymmetric device using NSMC as the negative electrode and MnO₂@MC-30 as the positive electrode is assembled. The assembled supercapacitor can deliver a maximum energy density of 44.0 W h kg⁻¹ with a high power density of 12 000 W kg⁻¹ and an outstanding cycling stability of 90% after 5000 cycles. This work combines interfacial methods with mesoporous carbon channels, providing new insights for the design of high-performance electrode materials.