PSEUDOCAPACITIVE BEHAVIOR OF Mn-Fe MIXED OXIDE FILMS PREPARED BY SOL-GEL METHOD

Abstract

   In this study, Mn-Fe mixed oxides with promising pseudocapacitive behavior were synthesized by sol-gel method. The oxide films were deposited on nickel substrates by spin-coating technique and were annealed at different temperatures ranged from 200 to 500 oC. Pseudocapacitive characteristics and electrochemical properties of the oxide electrodes were investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) methods. The results showed that in 2M KCl solution, these oxide films exhibited pseudocapacitive behavior with typical isosceles triangle shape of galvanostatic charge/discharge curves. Among the heat treated oxide films, the film annealed at 300 oC performed the highest specific capacitance of 341 F/g. After 500 cycle test, at the charge/discharge current density of 0.5 mA/cm2 this material maintained 73% the first capacitance with 97.3% coulombic efficiency. Electrochemical impedance spectroscopy results also demonstrated that annealing at high temperature lead to increases of charge transfer resistance and also diffusion impedances of the binary oxide materials.Keywords: sol-gel, mixed oxides, pseudocapacitor, supercapacitor