This work reports a flexible supercapacitor based on vanadium oxide–polyaniline composites (VP-1) with a large potential window and high energy density.
Electrochemical codeposition of vanadium oxide (V2O5) and polypyrrole (PPy) is conducted from vanadyl sulfate (VOSO4) and pyrrole in their aqueous solution to get V2O5-PPy composite, during which one-dimensional growth of polypyrrole (PPy) is directed. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the composite, while scanning electron microscopy (SEM) is used to investigate their morphologies. Cyclic voltammetry (CV), chronopotentiometry (CP) for galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) are used to study electrochemical activities and pseudocapacitive properties of the composite. The influences of VOSO4 to pyrrole ratio in the electro-codeposition solution on morphologies and pseudocapacitive properties of the composite are discussed. Due to the organic-inorganic synergistic effect, V2O5-PPy composite exhibits good charge-storage properties in a large potential window from -1.4 to 0.6 V vs SCE, with a specific capacitance of 412 F/g at 4.5 mA/cm(2). A model supercapacitor assembled by using the V2O5-PPy composite as the electrode materials displays a high operating voltage of 2 V and so a high energy density of 82 Wh/kg (at the power density of 800 W/kg).
In an aqueous mixture of manganese acetate, ammonium acetate and pyrrole, PPy and MnO2 composite materials (PPy‐MnO2) are synthesized by i‐t technology at 0.9 V vs. SCE. The influences of manganese acetate to pyrrole in the electro‐codeposition solution on morphologies and charge storage properties of the composite are discussed. PPy‐MnO2 composite materials as the electrode material exhibit a wide charge‐storage potential window of 1.2 V (between −0.3 and 0.9 V vs. SCE) and a high specific capacitance of 345.54 F g−1 at 2 mA cm−2. A symmetric flexible supercapacitor (PPy‐MnO2//PPy‐MnO2) is assembled by using PPy‐MnO2 composite electrodes. PPy‐MnO2//PPy‐MnO2 model supercapacitor displays almost 100% capacitance retention on the different bending angles. The energy density of 37.63 Wh kg−1 at the power density of 830 W kg−1 and an immense cyclic charge‐discharge stability, the specific capacitance is lost less than 3% after the 10,000 galvanostatic charge‐discharge cycles. The successful synthesis of high performance composite electrodes using electro‐codeposition method could open up new opportunities for high energy density supercapacitors.
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