Graphene-based flexible supercapacitors: Pulse-electropolymerization of polypyrrole on free-standing graphene films

A simple method has been implemented to create flexible, uniform graphene-polypyrrole composite films using a pulsed electropolymerization technique for supercapacitor electrodes. Applying the pseudocapacitive contribution of conformal redox-active polypyrrole to graphene supercapacitor electrodes results in high performance while still maintaining the inherent flexibility of graphene films. Specific capacitances as high as 237 F/g were obtained for a moderate total deposition time of only 120 s, which is approximately four times higher than the blank scaffold, graphene films. This flexible supercapacitor film exhibited very high energy and power densities with values of ∼33 Wh/kg and ∼1184 W/kg, respectively, at a scan rate of 0.01 V/s. This increase was attributed to the favorable nucleation of new polymer chains at defects on the graphene surface, which become less favorable as defect sites are occupied by existing polymer nanoparticles.