Morphological and electrochemical characterization of a poly(3-methylthiophene)/PVDF composite

Composite electrodes were prepared via electrochemical polymerization of 3-methylthiophene in porous PVDF membranes of various thicknesses. The electrochemical properties were determined by cyclic voltammetry and charge–discharge tests and the possible correlation of the results with the morphology of the host membranes was examined. The best definition of n- and p-doping/undoping processes and the biggest capacitance (82 F g−1) were obtained with a 27.5 μm-thick composite. Further characterization of this composite using electrochemical impedance spectroscopy revealed three behaviors associated with variation in the oxidation state of poly(3-methylthiophene) during transition from the n-undoping to p-doping states. The behavior of the charge transfer resistance and the double layer capacitance as a function of the applied potential were also determined.