Flexible and solid-state asymmetric supercapacitor based on ternary graphene/MnO2/carbon black hybrid film with high power performance

Reduced graphene oxide/manganese dioxide/carbon black (rGO/MnO2/CB) ternary film is prepared by a simple vacuum filtration method. MnO2 nano particles grow on both sides of the graphene layers serving as active sites for the electrochemical reactions which remarkably enhance the specific capacitance. While CB acts as spacers between the graphene layers preventing the restacking of graphene sheets and improves the conductivity between the basal planes of graphene sheets, leading to a better rate performance. Thanks to the synergistic effects of CB and MnO2, the capacitanceis improved to 209 F g(-1), which is much better than that of the binary graphene/CB film (96 F g(-1)) and maintains at 77 F g(-1) even at a fastscan rate of 1 V s(-1). The 1.8 V aqueous asymmetric supercapacitor based on rGO/MnO2(2.5)/CB (positive electrode) and rGO/CB (negative electrode) exhibits a large energy density of 24.3 Wh kg(-1) especially a high power delivery capability with an energy density of 10 Wh kg(-1) at the power density of 45 kW kg(-1). Furthermore, the energy density of the flexible solid-state asymmetric device based on this ternary film reaches 20 Wh kg(-1) and maintains 10 Wh kg(-1) at the power density of 21 kW kg(-1). (C) 2015 Elsevier Ltd. All rights reserved.