Electrostatic spray deposition of graphene nanoplatelets for high-power thin-film supercapacitor electrodes

Thin-film electrodes of graphene nanoplatelets (GNPs) were fabricated through the electrostatic spray deposition (ESD) technique. The combination of a binder-free deposition technique and an open pore structure of graphene films results in an excellent power handling ability of the electrodes. Cyclic voltammetry measurements of 1-μm-thick electrodes yield near rectangular curves even at a very high scan rate of 20 V s−1. Thin-film electrodes (1 μm thickness) show specific power and energy of about 75.46 kW kg−1 and 2.93 W h kg−1, respectively, at a 5 V s−1 scan rate. For the thin-film electrode, about 53 % of the initial specific capacitance of electrodes at low scan rates was retained at a high scan rate of 20 V s−1. Although the thickness of the thin-film electrodes has influence on their rate capability, an electrode with an increased thickness of 6 μm retained about 30 % if its initial capacitance at a very high scan rate of 20 V s−1. The results show that the ESD-fabricated GNP electrodes are promising candidates for thin-film energy storage for applications that require moderate energy density and very high power and rate handling ability.