Partially Reduced Graphene Oxide Paper: A Thin Film Electrode for Electrochemical Capacitors

A flexible, conductive graphene-paper electrode was prepared by a flow-directed filtration of graphene oxide dispersion followed by a gentle thermal reduction treatment of the filtrate. The prepared partially reduced graphene oxide paper (GOPpr) showed a dense packing of graphene sheets with a distinct interlayer distance of 4.35 Å. Its electrode quality for energy storage applications was tested by an electrochemical characterization in the aprotic electrolyte 1M TEABF4 in acetonitrile (AN) which is commonly used for supercapacitors. Within either the first positive or negative charging sweep, GOPpr features an electrochemical activation. As a result the graphene framework of the GOPpr becomes accessible for ion insertion and release. The achieved specific capacitance in galvanostatic discharge measurements reached up to 199 Fg−1 at 0.1 Ag−1 for a positively activated and polarized electrode. Even at high specific currents of 10 Ag−1 this value didn't drop below 145 Fg−1. An even higher specific capacitance was determined from cyclic voltammetry where the positively activated electrode yielded up to 270 Fg−1 during the discharge sweep. It's flexible nature, the simple processability and the outstanding rate handling capability makes GOPpr an excellent candidate for a positive electrode in bendable supercapacitors and lithium capacitors.