LAUSR

Abstract 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 H 2 SO 4 /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 VO x . The capacitive properties were studied in aqueous solutions of H 2 SO 4 and Li 2 SO 4 , and in an acetonitrile solution of HBF 4 /TBABF 4 . 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 HBF 4 /TBABF 4 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 HBF 4 /TBABF 4 . The charge–discharge results for asymmetric supercapacitor reveal that the PPy-VO x -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.