▎ 摘　　要

A High energy, asymmetric supercapacitor (ASC) has been constructed using porous manganese oxide (MnO2) nanostructures as positive electrode and reduced graphene oxide (RGO) as negative electrode in 1 M Na2SO4 electrolyte. The ASC device exhibits excellent electrochemical performance, when the device is assembled with optimal mass ratio. The energy density is 22.2 W h kg(-1) at a power density of 101 W kg(-1), when the device is cycled reversibly in the high potential range of 0-2 V. The asymmetric supercapacitor device also exhibits a superior cycling stability with 90% retention of the initial specific capacitance after 3000 cycles.