High-performance and flexible electrochemical capacitors based on graphene/polymer composite films

We report the fabrication of electrochemical capacitors (ECs) with high energy and power densities based on the compact reduced graphene oxide (rGO)/poly (vinyl pyrrolidone) (PVP) composite films. In these ECs, rGO/PVP composite films were directly used as the electrode material without blending any binders or conductive additives because of their high mechanical strength (121.5 +/- 10.8 MPa) and electrical conductivity (247.9 S m(-1)). The solid-state ECs based on the rGO/PVP composite containing 55% rGO (by weight) showed high gravimetric and volumetric specific capacitances, good rate-capability, excellent flexibility and satisfactory electrochemical stability. Furthermore, the EC based on the composite film containing 71% (by weight) of rGO with an organic electrolyte exhibited a high power density (40 W cm(-3)) and a high energy density (2.5 mW h cm(-3)) at a current density of 1 A g(-1) by taking account of the volumes of its electrodes and separator.