Reduced graphene oxide as a multi-functional conductive binder for supercapacitor electrodes

To date, significant effort has been focused on the active materials in the supercapacitor electrodes. However, very little has been done for the binder materials. Insulating fluorinated polymer binders, which are used for fabrication of carbon electrodes in supercapacitors, reduce electrode conductivity, capacitance, and rate performance. Here we propose to use reduced graphene oxide (rGO) as a multi-functional conductive binder as a general strategy for manufacturing freestanding, flexible, high-performance supercapacitor electrodes from various micron-sized porous carbons. The two-dimensional structure, high specific surface area and effective electronic conductivity of rGO enable us to eliminate the addition of insulating binder, conductive additive, and current collector. The synergetic effect of rGO with carbon materials produces a 3D conductive network and enlarges the electrode/electrolyte interface, enhancing electrode capacitance and rate performance in both aqueous and non-aqueous electrolytes. Using rGO as a binder, we prepared various high-performance and flexible electrodes from activated carbon powders, fibers and spheres, in which both the composition and thickness are controllable. This demonstrates that rGO can be used as a binder for porous carbons with different morphologies. As this strategy is environmentally friendly and easy to scale-up, we believe it is a promising method for fabrication of all-carbon and composite electrodes.