Evaluation of ZnMnFe2O4 as supercapacitor

Supercapacitors as a storage electrical energy system due to their high power density and charge/discharge cycle number and suitable specific energy, have very intention in new research and industrial application. Ferrite compounds have good oxidation state and with nanoparticle synthesis of that, have good active surface area, so could be a valuable choice for use as electrodic active material in supercapacitor that have electrical double layer and pseudocapacitor property. In this work, firstly synthesize ZnMnFe2O4 by solution chemical codepositon method and produced nanosize powder characterized by SEM, XRD, FTIR and VSM for demonstration of morphology, crystal lattice, structure and magnetic properties. SEM image reveals semispherical particle shape with size range less than 100 nm, and XRD analyze exhibits spinel lattice structure with rearrangement of Zn and Mn cation in Octahedral and Tetrahedral site of Fe3O4 spinel structure. Electrochemical evaluation of capacitive properties of ferrite compound is done by cyclic voltammetry, chronopotentiometery and electrochemical impedance spectroscopy method. At the first, the ferrite powder mixed with 15 weight percent acetylene black as conductive agent and 5 weight percent PVDF solute in NMP as binder and then a drop of composite coated on glassy carbon electrode that used as working electrode in three electrodic test. Primarily, best electrolyte was selected between a series of alkali and chloride salt solution and potassium hydroxide and chloride was boarder domain in CV diagrams. Suitable concentration of these solutions was obtained too. Cyclic voltammograms appears EDLC and pseudocapacitance property for ZnMnFe2O4 and by laviron equation of peak current versus scan rate, surface active area was calculated. 283 By three and two electrodic chronopotentiometery test, specific capacity and columbic efficiency of ferrite compound was obtained. In two electrodic test, prepared composite was coated in two pieces of graphite with 1*1 cm dimension that separated with a cotton paper as insulator. EIS test reveals specific capacity and electrochemical charge transfer between ferrite and proton and appears pseudocapacutive as well as ELDC property of ZnMnFe2O4 compound.