A carbon electrode fabricated using a poly(vinylidene fluoride) binder controlled the Faradaic reaction of carbon powder

A carbon electrode for capacitive deionization (CDI) was fabricated by casting a slurry that was a mixture of activated carbon powder (ACP) and poly(vinylidene fluoride) (PVdF) dissolved in di-methylacetamide (DMAc) on the current collector. Electrochemical properties and adsorption/desorption behaviors of the carbon electrodes prepared with different PVdF contents (9–18 wt%) were characterized using cyclic voltammetry, chronoamperometry, and impedance spectroscopy methods. From the SEM images, carbon powders were coated with the PVdF binder and bound together. Capacitances of carbon electrodes were estimated in the range of 75.3–69.6 F/g, decreasing in tandem with PVdF contents, but the decrease was not significant. From cyclic voltammetric and chronoamperometric measurements, the electrochemical behaviors of the carbon electrodes were dependent not only on the electric double layer capacitance, but also on Faradaic reactions. However, Faradaic currents resulted from an electrochemical redox reaction of carbon surface controlled by the polymer binder. These results indicate that the electrochemical reaction on the carbon surface was suppressed due to the PVdF binder.