Electrosynthesis of polypyrrole-vanadium oxide composites on graphite electrode in acetonitrile in the presence of carboxymethyl cellulose for electrochemical supercapacitors

One-step electrochemical synthesis of polypyrrole-vanadium oxide (PPy-VOx) composites was performed on the Vanadium-intercalated pencil graphite (PG) surface in an acetonitrile solution with the presence of carboxymethyl cellulose (CMC). Both intercalated surface and composite coating were characterized using SEM-EDX Spectroscopy and X-Ray Diffraction (XRD) techniques. The capacitive properties of the coating were elaborated in an H2SO4/water medium using galvanostatic charge-discharge, potential cycling, and electrochemical impedance spectroscopy methods in comparison with the coatings prepared without additives. While V-intercalation provides a significant increase in the specific capacitance, the carboxymethyl cellulose enhances the cyclic performance of the composite. The improvement at the capacitance of the composite may be due to the homogenous distribution as well as the synergetic effect between PPy and VOx. The capacitive properties were studied in aqueous solutions of H2SO4 and Li2SO4, and in an acetonitrile solution of HBF4/TBABF4. The specific capacitance value of the composite coating on the V-intercalated pencil graphite was determined as 204 F g−1 in an acetonitrile solution of HBF4/TBABF4 for a mass loading of 10.0 mg cm−2 at 2.0 A g−1, when the capacitance of bare graphite was subtracted. The two-electrode supercapacitors composed of both asymmetric and symmetric configurations were also prepared and examined in an acetonitrile/adiponitrile solution of HBF4/TBABF4. The charge-discharge results for asymmetric supercapacitor reveal that the PPy-VOx-CMC composite coating (20 mg cm−2) on V-intercalated graphite paper represents a high energy density of 18 Wh.kg−1 and a high power density of 0.43 kW kg-1 at 0.5 A g−1, as well as a stable cycle life at the potential range of 1.2 V.