Nanoarchitectured MnO<sub>2</sub> Confined to Mesoporous Carbon Microspheres as Bifunctional Electrodes for High-Performance Supercapacitors and Lithium-Ion Capacitors
Qizhi Liu, Cheng Ma, Wenming Qiao, Licheng Ling, Jitong Wang
Abstract
Manganese dioxide (MnO2) is an outstanding electrode material to obtain high pseudocapacitance and specific capacity, but the structure pulverization and poor conductivity during the charge/discharge process are the inevitable problems. Restricting nanoscaled MnO2 in stable pore channels of mesoporous carbon spheres can effectively inhibit its pulverization and obtain an excellent conductive network. Herein, nanoarchitectured MnO2/mesoporous carbon microspheres (MCMs) as bifunctional electrodes for supercapacitors and lithium-ion capacitors (LICs) were prepared through a charily designed facile stratagem containing spray drying and the subsequent redox reaction. The MnO2/MCMs electrode delivers a gravimetric capacitance of 188 F g–1 and a volumetric capacitance of 347 F cm–3 with an outstanding cyclic performance of 90% capacitance retention after 1000 cycles at 1 A g–1, which is ideal for supercapacitors. Moreover, the assembled MnO2/MCMs//activated carbon (AC) lithium-ion capacitors exhibit a long cyclic life of 1300 times with 7.7% capacity loss at 1 A g–1 and a superior energy density of 147 Wh kg–1, as well as a power density of 4952 W kg–1, demonstrating its feasibility on LIC anodes. The excellent electrochemical performance is ascribed to the synergistic effect between MnO2 and mesoporous carbon microspheres, which improves the electrochemical capacities and cyclic stability of both systems. This work provides the possibility for applying bifunctional MnO2/MCMs as electrode materials for high-efficiency hybrid systems.