Highly Conductive and\nPorous Activated Reduced Graphene\nOxide Films for High-Power Supercapacitors

Abstract

We present a novel method to prepare highly conductive,\nfree-standing,\nand flexible porous carbon thin films by chemical activation of reduced\ngraphene oxide paper. These flexible carbon thin films possess a very\nhigh specific surface area of 2400 m² g^–1 with a high in-plane electrical conductivity of 5880 S m^–1. This is the highest specific surface area for a free-standing carbon\nfilm reported to date. A two-electrode supercapacitor using these\ncarbon films as electrodes demonstrated an excellent high-frequency\nresponse, an extremely low equivalent series resistance on the order\nof 0.1 ohm, and a high-power delivery of about 500 kW kg^–1. While higher frequency and power values for graphene materials\nhave been reported, these are the highest values achieved while simultaneously\nmaintaining excellent specific capacitances and energy densities of\n120 F g^–1 and 26 W h kg^–1, respectively.\nIn addition, these free-standing thin films provide a route to simplify\nthe electrode-manufacturing process by eliminating conducting additives\nand binders. The synthetic process is also compatible with existing\nindustrial level KOH activation processes and roll-to-roll thin-film\nfabrication technologies.