MnO/few-layered-graphene composite as a high performance electrode material in aqueous supercapacitors

•MnO/FLG composite is synthesized by graphenothermal reduction process.•MnO particles are decorated on graphene sheets of FLG in MnO/FLG composite.•MnO/FLG composite exhibits high specific mass capacitance value of ~778.5 F/g.•Combination of FLG’s EDLC and MnO’s pseudo-capacitance is seen. MnO nanonetwork decorated few layered graphene (FLG) composite was prepared using a completely solid state process and when tested as an electrode material in an aqueous supercapacitor it delivered an excellent specific capacitance (SC) of 778.5 F/g at a current density of 0.5 A/g and retained 93% of the SC even after 1000 charge-discharge cycles. Cyclic Voltammetry (CV) studies showed that the SC of the composite is the resultant of the combined electric double layer capacitance of FLG and pseudo-capacitance of MnO. The negligible change in the nature of CV curves recorded at different scan rates showed that the composite is electrochemically stable. Also, the high discharge capacitance is explained in terms of composite’s porosity, which shortens the cation path into the electrode matrix.