Flexible asymmetric supercapacitor based on MnO2 honeycomb structure

A flexible asymmetric supercapacitor with high energy density was constructed by using a flexible substrate of carbonized silk-fabrics decorated with carbon nanotube, electroplating MnO2 nanosheets and dip-coating activated carbon powders as the positive and the negative electrodes, respectively. By controlling the electroplating time, the MnO2 nanosheets can be self-assembled to honeycomb structure and showed excellent electrochemical performance in 1 mol/L Na2SO4 electrolyte with SC950-EP30 performing the best. It exhibited a high specific capacitance (1110.85 F/g at a current density of 1 A/g based on the mass of MnO2) and superior rate capability (77.44% capacity retention from 1 A/g to 10 A/g). Thus, the optimal asymmetric device assembled with this material as positive electrode can deliver a maximum energy density of 43.84 Wh/kg and a maximum power density of 6.62 kW/kg.