Assembly of manganese dioxide/polypyrrole electrode//activated carbon flexible asymmetric supercapacitor with excellent electrochemical performances

Manganese dioxide (MnO2) often suffers from a slow electron transport, and so improving the charge transport capability of MnO2 is imminent. In here, crossed MnO2 nanosheets grown on carbon cloth (CC) are fabricated firstly and subsequently coated with a layer of polypyrrole (PPy) to prepare CC/MnO2/PPy (CC/MP) electrode. At 1 A g(-1), the prepared electrode is able to deliver a specific capacitance of 328 F g(-1). The flexible asymmetric supercapacitor consists of CC/MP and CC/activated carbon (CC/AC) separately as positive and negative electrodes and PVA-H2SO4 as gel electrolyte. The assembled device exhibits a specific capacitance of 123.96 F g(-1) at 10 mV s(-1), reaches a voltage window of 1.6 V, has a capacitance retention of 96.46% after 8000 cycles, and produces an energy density of 25.67 W h kg(-1) at a power density of 401.79 W kg(-1), as well as an energy density of 8.78 W h kg(-1) at a power density of 3902.22 W kg(-1). The two devices in series can illuminate 1.8 V red light-emitting diode (LED) light. These excellent electrochemical properties are ascribed to the unique heterostructure of the electrode composite. The outcomes indicate that the prepared CC/MP electrode and the corresponding device have huge potential applications in next-generation high-performance supercapacitor devices.