Polypyrrole–oxalate and polypyrrole–sulfate electrodes for supercapacitor applications

Polypyrrole–oxalate (PPy-O) electrodes were electropolymerized from the oxalate solutions containing oxalic acid and pyrrole (Py) monomer. The structural, electrochemical and capacitive behaviors were studied depending on the monomer concentration, the applied current density and the film thickness. PPy-O has very ordered structural and electronic properties. The specific capacitance value was found as 657.1 F/g, but the lifetime was very short. Polypyrrole–sulfate (PPy-S) electrodes were electropolymerized from the sulfate solutions containing sulfuric acid and Py monomer. They were investigated as a function of the monomer concentration and the applied current density. The PPy-S electrodes are in disordered structure. The highest specific capacitance value was found as 1066.7 F/g. A symmetric capacitor was fabricated from PPy-S electrodes. The energy density is 26.4 Wh/kg and power density is 155.4 W/kg. Those supercapacitors are convenient to use for devices working at a low-medium power density.