Synthesis of Ferrites as an Electrode Material for Super capacitor Application

Abstract

Ferrites have been widely investigated for supercapacitor application. The doping of ferrites with various metal enhances the electrochemical performance. In this study ferritebased electrodes were synthesized using coprecipitation method. The synthesized materials are ZnFe2O4, Zn0.5Mg0.5Fe2O4, Zn0.5Co0.5Fe2O4, and Zn0.5Mg0.25Co0.25Fe2O4. X-ray Diffraction confirmed FCC cubic structure of ferrites with the crystallite size of 15,17,10 and 18 nm for ZnFe2O4, Zn0.5Mg0.5Fe2O4, Zn0.5Co0.5Fe2O4, and Zn0.5Mg0.25Co0.25Fe2O4 respectively. Scanning electron microscopy revealed that the particles are spherical, and the average size is 55 nm, 68.1 nm, 33.1 nm and 143 nm respectively. Elemental composition was determined by Energy Dispersive X-Ray Spectroscopy. Functional group analysis was done using Fourier Transform Infrared. spectroscopy. Synthesized electrode material was then deposited on Ni foam using Nafion as a binder to study their electrochemical properties. The substrates were dried overnight at 60℃ in vacuum oven; and the loaded mass on Ni foam was around 0.006-0.008 mg. Electrochemical properties such as specific capacitance, resistance, current density, and discharge time were studied via Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Galvanostatic Charge discharge (GCD). At various scan rates (5 mV/s, 10 mV/s, 20 mV/s, 50 mV/s, 100 mV/s and 200 mV/s), cyclic voltammetry was investigated. Comparative analysis of CV at 5 mVs-1 shows the specific capacitance for Zn0.5Co0.5Fe2O4 as 325.67 F/g. The specific capacitance shown by ZnFe2O4 is 306.58 F/g, Zn0.5Mg0.5Fe2O4 is 201.05 F/g and Zn0.5Mg0.25Co0.25Fe2O4 is 94.527F/g. The Redox peak current increases with increasing scan rates. The shape of the CV represents pseudocapacitive behavior of synthesized electrode. The lowest resistance of 1.15 ohm was exhibited by Zn0.5Co0.5Fe2O4 followed by ZnFe2O4(1.6 ohm), Zn0.5Mg0.5Fe2O4(1.15 ohm) and Zn0.5Mg0.25Co0.25Fe2O4(1.59 ohm). GCD was done at the current density of 0.5A/g. The capacitance shown by GCD for ZnFe2O4 is 380.13 F/g, Zn0.5Mg0.5Fe2O4 is 309.57 F/g, Zn0.5Co0.5Fe2O4 is 530 F/g and Zn0.5Mg0.25Co0.25Fe2O4 is 260.96 F/g. Putting together this study lays the foundation for more investigation using Zn0.5Co0.5Fe2O4 ferrite for supercapacitor application.