Synergistic Effect of Electrolytes on the Electrochemical Performance of CoFe₂O₄ Nanoparticles as Anode Materials for Supercapacitor Applications

This article describes the synthesis of CoFe₂O₄ nanoparticles, which can be used to form an anode for supercapacitor applications. The CoFe₂O₄ nanoparticles were synthesized via a hydrothermal route. The structural parameters of the prepared samples were characterized by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), and the supercapacitive behavior was evaluated by cyclic voltammetry plots, galvanostatic charge–discharge plots, and electrochemical impedance spectroscopy (EIS). Rietveld refinement confirmed the spinel structure of the CoFe₂O₄ nanoparticles with space group Fd3m. The FE-SEM micrographs confirmed the spherical shape of the CoFe₂O₄ nanoparticles, with a mean particle size of 58 nm. The electrochemical performance of the samples was checked in different aqueous electrolytes: Na₂SO₄ and KOH. The nanoparticles exhibited differences in capacitive behavior in different aqueous electrolytes, with higher specific capacitance (362 F/g) in the KOH electrolyte due to its greater molar ionic conductivity in comparison to the Na₂SO₄, and a low resistance value obtained from impedance measurements was observed for CoFe₂O₄ nanoparticles. The cyclic stability of CoFe₂O₄ in KOH electrolyte, with 82.16% retention after 2000 cycles at current density of 1 A/g, evidenced its outstanding performance, with exceptionally high specific capacitance of 314 F/g.