Evaluation of ZnMnFe2O4 as supercapacitor

Supercapacitors as a storage electrical energy system due to their high power density andcharge/discharge cycle number and suitable specific energy, have very intention in new researchand industrial application. Ferrite compounds have good oxidation state and with nanoparticlesynthesis of that, have good active surface area, so could be a valuable choice for use aselectrodic active material in supercapacitor that have electrical double layer and pseudocapacitorproperty.In this work, firstly synthesize ZnMnFe2O4 by solution chemical codepositon method andproduced nanosize powder characterized by SEM, XRD, FTIR and VSM for demonstration ofmorphology, crystal lattice, structure and magnetic properties. SEM image reveals semisphericalparticle shape with size range less than 100 nm, and XRD analyze exhibits spinel lattice structurewith rearrangement of Zn and Mn cation in Octahedral and Tetrahedral site of Fe3O4 spinelstructure.Electrochemical evaluation of capacitive properties of ferrite compound is done by cyclicvoltammetry, chronopotentiometery and electrochemical impedance spectroscopy method. At thefirst, the ferrite powder mixed with 15 weight percent acetylene black as conductive agent and 5weight percent PVDF solute in NMP as binder and then a drop of composite coated on glassycarbon electrode that used as working electrode in three electrodic test. Primarily, best electrolytewas selected between a series of alkali and chloride salt solution and potassium hydroxide andchloride was boarder domain in CV diagrams. Suitable concentration of these solutions wasobtained too. Cyclic voltammograms appears EDLC and pseudocapacitance property forZnMnFe2O4 and by laviron equation of peak current versus scan rate, surface active area wascalculated. By three and two electrodic chronopotentiometery test, specific capacity and columbic efficiencyof ferrite compound was obtained. In two electrodic test, prepared composite was coated in twopieces 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 protonand appears pseudocapacutive as well as ELDC property of ZnMnFe2O4 compound.

کلیدواژه ها:

Electrochemical double layer capacitance (ELDC) ، Pseudocapacitance ، Ferritecompound ، ZnMnFe2O4