Electrochemical performances of poly(3,4-ethylenedioxythiophene)–NiFe 2O 4 nanocomposite as electrode for supercapacitor

Abstract

Poly 3,4-ethylenedioxythiophene (PEDOT)-based NiFe 2O 4 conducting nanocomposites were synthesized and their electrochemical properties were studied in order to find out their suitability as electrode materials for supercapacitor. Nanocrystalline nickel ferrites (5–20 nm) have been synthesized by sol–gel method. Reverse microemulsion polymerization in n-hexane medium for PEDOT nanotube and aqueous miceller dispersion polymerization for bulk PEDOT formation using different surfactants have been adopted. Structural morphology and characterization were studied using XRD, SEM, TEM and IR spectroscopy. Electrochemical performances of these electrode materials were carried out using cyclic voltammetry at different scan rates (2–20 mV/s) and galvanostatic charge–discharge at different constant current densities (0.5–10 mA/cm 2) in acetonitrile solvent containing 1 M LiClO 4 electrolyte. Nanocomposite electrode material shows high specific capacitance (251 F/g) in comparison to its constituents viz NiFe 2O 4 (127 F/g) and PEDOT (156 F/g) where morphology of the pore structure plays a significant role over the total surface area. Contribution of pseudocapacitance ( C FS) arising from the redox reactions over the electrical double layer capacitance ( C DL) in the composite materials have also been investigated through the measurement of AC impedance in the frequency range 10 kHz–10 mHz with a potential amplitude of 5 mV. The small attenuation (∼16%) in capacitance of PEDOT–NiFe 2O 4 composite over 500 continuous charging/discharging cycles suggests its excellent electrochemical stability.