Controllable synthesis of hierarchically porous polyaniline/MnO2 composite with wide potential window towards symmetric supercapacitor

MnO2 composites are appealing electrode materials for supercapacitors because of low cost, environmental friendliness, and high electrochemical activity. Herein, in an attempt to overcome the poor conductivity and limited potential window, the polyaniline (PANI) hydrogel is employed as the substrate to synthesize the PANI/ MnO2 composite via the self-sacrifice reaction with KMnO4. The PANI/MnO2 composite prepared under heating condition (PM-H) shows hierarchically porous structure with large specific surface area/pore volume and facilitated electron/ion conduction. As a result, it delivers wide potential window of -1.1-1.1 V and high specific capacitances of 314 F g(-1) at 1 A g(-1) and 263 F g(-1) at 5 A g(-1) (83.8% capacitance retention) in the three -electrode measurement. Moreover, the assembled symmetric supercapacitor delivers large operation window (0-1.8 V) and high energy/power density, e.g., a maximum energy density of 23.2 Wh kg(-1) with power density of 720 W kg(-1). Therefore, the present work paves a new way to construct PANI/MnO2 nanocomposite with ideal nanostructure and optimized electrochemical behavior for symmetric supercapacitor.