Fe3+/Fe2+ redox electrolyte for high-performance polyaniline/SnO2 supercapacitors

Abstract The Fe 3+ /Fe 2+ redox electrolyte for use in polyaniline/tin oxide (PANI/SnO 2 ) supercapacitors was reported. The influences of redox electrolyte based on different Fe 3+ /Fe 2+ ion pair concentrations in 1 mol/L H 2 SO 4 solution on the pseudocapacitive behaviors of PANI/SnO 2 supercapacitor were investigated. The electrochemical properties of the supercapacitor were studied by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. It is found that the performance of the supercapacitor is the best when the Fe 3+ /Fe 2+ concentration is 0.4 mol/L and its initial specific capacitance is 1172 F/g at an applied current density of 1 A/g. The long-term cycling experiment shows good stability with the retention of initial capacitance values of 88% after 2000 galvanostatic cycles. The experimental results testify that using Fe 3+ /Fe 2+ redox electrolyte has a good prospect for improving the performances of energy-storage devices.