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Nano-sized PPy/CrOx composite was deposited on a graphite foil (GF) surface using multi-cyclic voltammetry via simultaneous synthesis of PPy and CrOx from an acetonitrile/HBF4/LiBF4/solution containing pyrrole and Cr(BF4)3. The electrochemical properties of the composite were examined using CV and EIS techniques in a Li2SO4 solution, and it was characterized by FESEM, EDX, TEM, and XPS methods. This study revealed that oxygen-deficient CrOx containing Cr(II), Cr(III), and Cr(VI) oxidation states could be synthesized in acetonitrile, unlike in aqueous medium. CrOx with a 6% ratio was encapsulated within the partially oxidized PPy clusters thanks to the simultaneous synthesis of components. The specific capacitance of the PPy/CrOx composite-coated electrode with a mass loading of 4 mg cm-2 was 150 F g-1 at 50 mV s-1, which was higher than that of PPy. Thus, it could be revealed that a small amount of nano CrOx provided a considerable pseudocapacitive contribution to the composite. An asymmetric supercapacitor cell was constructed with PPy/CrOx composite- and PVC/carbon-coated GF electrodes in a polyvinyl alcohol (PVA)/Li2SO4 gel electrolyte. The cell exhibited an energy density of 20.1 Wh kg-1 and a power density of 3.50 kW kg-1 at 5 A g-1. [ABSTRACT FROM AUTHOR]

Summary: Polypyrrole (PPy)‐based composites containing nanostructured VOx, PbOx, and MnOx are galvanostatically synthesized on exfoliated graphite papers (1.0 and 6.25 cm2) formed as a result of the intercalation with their metals. Both intercalation and synthesis are performed in the synthesis solution containing metal(II)tetrafluoroborate salts, pyrrole monomer, HBF4, H2O, Triton‐X 100 (TX100), and carboxymethyl cellulose (CMC). The mass loading of the composite at the electrode is maintained at 10 mg cm−2. Symmetric and asymmetric unit cells are prepared in polyvinyl alcohol (PVA)/H2SO4 (1:1) gel electrolyte using composites synthesized on the treated graphite paper electrode. The electrical properties of these cells are examined by electrochemical impedance spectroscopy and their capacitive properties by cyclic voltammetry and galvanostatic‐charge discharge test. The asymmetrical cell, prepared with PPy/PbOx/CMC composite having energy density and cycle life better than others, exhibits 7.77 Wh kg−1 and 0.51 kW kg−1 at a working voltage of 1.4 V, considering the total mass of all sub‐components. The three‐cell asymmetric stack design, which is prepared using these composite‐coated electrodes, achieves a coulombic efficiency of 76% at 4.2 V. Finally, an electronic control system (DC/DC buck‐boost converter) is designed and implemented to manage the charge and discharge cycles of single‐cell and bipolarly connected stack to operate the asymmetric supercapacitor arrays with high performance. [ABSTRACT FROM AUTHOR]

Summary: Polypyrrole (PPy) and nanostructured Ag‐Ag2O were co‐deposited galvanostatically on the Ag‐intercalated graphite electrode in acetonitrile/TBABF4 solution with AgBF4, Py, HBF4, H2O, and sodium carboxymethyl cellulose (CMC). The effects of additives and intercalation on the capacitive behaviors of PPy‐Ag‐Ag2O‐CMC composite (4.0 mg/cm2) were studied in H2SO4 (0.1 M) solution by using cyclic voltammetry and electrochemical impedance spectroscopy methods. The composite coating was characterized using X‐ray photoelectron spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD), Brunauer, Emmett, and Teller, and scanning electron microscopy (SEM) energy dispersive X‐ray spectroscopy. The incorporation of nano‐sized Ag‐Ag2O particles and CMC into the composite has significant impacts on the morphology, which also greatly influences the capacitive performance. XRD and SEM studies showed that the electrochemical intercalation of silver in acetonitrile medium provided partially exfoliated surface of graphite, thus the capacitive properties further enhanced. The capacitive properties of the composite coating were also tested using the galvanostatic charge–discharge method. The specific capacitance of the composite coated electrode was calculated as 500 F/g at 2.0 A/g in H2SO4 solution by subtracting the capacitance of bare graphite electrode. Asymmetric and symmetric supercapacitor configurations were utilized to examine the capacitive performance of PPy‐Ag‐Ag2O‐CMC composite (10 mg/cm2) on Ag‐intercalated graphite paper. The asymmetric supercapacitor providing a power density of 0.51 kW/kg at 2.0 A/g and an energy density of 23.6 Wh/kg maintains 62% of its capacitance after 5000 cycles. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The study depicts a one-step electrochemical synthesis of composite based on polypyrrole (PPy) and SbO x (Sb 2 O 3 , Sb 2 O 5) on the graphite surface for the supercapacitor electrode in an acetonitrile solution including pyrrole monomer and Sb(BF 4) 3. PPy/SbO x composite on graphite plate is characterized using XPS, XRD, TEM, BET, and FESEM by comparing it with PPy homopolymer prepared in the same way. SbO x forms in nano-size and homogeneously encapsulates in PPy due to their simultaneous synthesis. The average pore size of the composite coating is 23.9 nm. The coated PG electrodes are tested in an H 2 SO 4 electrolyte using CV, EIS, and GCD methods. SbO x nanoparticles enhance the capacitive performance of PPy due to the contribution of its catalytic and pseudocapacitive properties. The specific capacitance of the PPy/SbO x -coated PG electrode is 389.5 F g−1 at 5 A g−1 for 1.0 mg cm−2 loading. PPy/SbO x is synthesized in the presence of carboxymethyl cellulose (CMC) to provide stability to the coating. An asymmetric supercapacitor cell is fabricated by assembling the PPy/SbO x /CMC-coated and activated carbon-based graphite paper electrodes (10 mg cm−2 loading). While the potential window expands to 1.4 V, it delivers an energy density of 8.3 Wh kg−1, a power density of 3.5 kW kg−1, and a coulombic efficiency of 90% at 5 A g−1. Post-mortem analysis reveals that structural degradation of PPy in the composite limits long-term stability. • PPy and SbO x are cosynthesized at one step on graphite from Py and Sb(BF 4) 3 in acetonitrile. • TEM results show the encapsulation of SbO x (Sb(III) and Sb(V)) into the growing PPy. • 1.3% nano-sized SbO x dispersed uniformly in composite enhances specific capacitance. • Fabricated asymmetric supercapacitor cell delivers 3.5 kW kg− 1 and 8.3 Wh kg− 1 at 5 A g-1. • Cell displays a nearly rectangular shape at a 1.4 V potential window with 90% efficiency. [ABSTRACT FROM AUTHOR]