Construction of hollow mesoporous PPy microsphere nanostructures coated with MnO2 nanosheet as high-performance electrodes for supercapacitors

In this work, hollow mesoporous PPy microspheres were prepared by using mesoporous SiO2 as a hard tem-plate, and hollow mesoporous PPy@MnO2 composites were successfully synthesized by a low-temperature redox reaction. The unique heterogeneous structure can realize the complementary advantages of the two materials. PPy can be used as a template to support the whole structure, and the design of the hollow structure will further buffer the volume change during cycling. In addition, the mesoporous structure will further increase its specific surface area and porosity, thereby enhancing the stability of its overall structure and inter-nal electron transport, and significantly increasing the number of active sites. Thus, the synthesized hollow mesoporous PPy@MnO2 electrode has outstanding electrochemical properties with a specific capacitance of 713 F g-1 at 1 A g-1 and a 92 % retention rate after 5000 cycles at 4 A g-1. The asymmetric supercapacitor constructed using PPy@MnO2 as the positive electrode material achieved a high energy density of 40.8 Wh kg-1 at a power density of 720 W kg-1. This work inspires a simple idea for designing hollow mesoporous nanocomposite electrodes with excellent electrochemical performance and provides a high-performance super -capacitor material for its practical applications.