Electrochemical characterization of poly(3,4-ethylene dioxythiophene) based conducting hydrogel networks

Poly(3,4-ethylene dioxythiophene), a conjugated polymer, doped with excess of polystyrenesulfonate (PSS), has been assembled into a mesoscopic conducting network in the form of a hydrogel. When used as an electrode, the material shows fast electrochemical kinetics as evident from cyclic voltammetry, chronopotentiometry, and impedance measurements. Due to high ionic mobility in the material, the electrochemical process is not limited by ion diffusion in the electrode, as normally is the case for conducting polymers, but by the resistance in the electronically conducting network. This resistance is decreased by growing another conducting polymer, polypyrrole (PPy), inside the hydrogel. Homogeneous deposition of PPy is confirmed by atomic force microscopy. The composite hydrogel also shows larger capacitance, only slightly affecting the kinetics of the electrode. Since the material can be charged and discharged in a very short time, application of such electrodes in high power density supercapacitors has been envisaged.