An interleaved porous laminate composed of reduced graphene oxide sheets and carbon black spacers by in situ electrophoretic deposition†
Although the graphene-based materials have a great potential to be used for various energy storage devices, the expected performance of graphene has not been achieved yet seemingly due to the lack of interconnected porosity and actively-exposed surface area that should be developed in the re-stacked graphene electrodes. Herein we used an electrophoretic deposition (EPD) method to fabricate a binder-free porous supercapacitor electrode composed of reduced graphene oxide (RGO) sheets and conductive carbon black (CB) particles. Applying EPD for an electrostatically-stabilized aqueous mixture of RGO and CB nanoparticles, the electrophoretic squeezing force in EPD induced the RGO sheets to align in the in-plane direction along with the CB particles placed in the interlayers of RGO. The developed ladder-like interleaved composite structure allowed a desirable porosity network and conductive path for a facile movement of ions and electrons. Controlling the ratios of concentrations (Cs,RGO/Cs,CB) and/or zeta potentials (ξRGO/ξCB) of the RGO and CB nanoparticles in aqueous mixtures, different nanostructures of the interleaved RGO/CB laminates could be fabricated. Thoroughly tested as a supercapacitor electrode in an organic electrolyte (TEA BF4), the developed RGO/CB electrodes provided excellent performance of the specific capacitance of 218 F g−1 at a scan rate of 1 mV s−1 (133.3 F g−1 at a current density of 2 A g−1), energy density of 43.6 W h kg−1 and power density of 71.3 kW kg−1. It is believed that an ideal performance of intrinsic graphene properties could be exerted by the unique nanostructure of binder-free interleaved graphene laminates as developed by the scalable in situ EPD process for large-volume production.