Construction of vertically aligned PPy nanosheets networks anchored on MnCo2O4 nanobelts for high-performance asymmetric supercapacitor

Abstract

Three-dimensional self-assemble polypyrrole@MnCo2O4 nanoarchitectures on graphite foam are fabricated via hydrothermal method and in situ polymerization process. During polymerization, the dopant p-toluenesulfonic acid can partially etch the MnCo2O4 nanobelts, while the dissociated Mn/Co ions may lead to the formation of metal-N bond in the polypyrrole nanosheets. The vertically aligned conductive polypyrrole nanosheets can facilitate the electrons transfer, while the porous structure can store electrolyte and increase the active materials utilization efficiency. Therefore, the polypyrrole@MnCo2O4/graphite foam composite exhibits a specific capacitance of 2364 F g−1 (328 mA h g−1 when normalized to specific capacity), with good rate performance and cycling stability. An asymmetric supercapacitor is assembled with the composite and activated microwave exfoliated graphite oxide as the positive and negative electrode, respectively. A highest energy density of 25.7 Wh kg−1 and power density of 16.1 kW kg−1 are obtained, which is comparable to most of the high-end supercapacitor electrodes. Furthermore, a capacitance retention of 85.5% is obtained after 10000 cycles.