Electrochemical Performance of Co_1-xMn_xFe₂O₄ Decorated Nanofiber Polyaniline Composites

The current work is concerned with preparing cobalt manganese ferrite (Co_1-xMn_xFe₂O₄) with different concentrations of cobalt and manganese (x = 0.2, 0.4, and 0.6) and decorating it with polyaniline (PAni) for use in supercapacitive applications. The results of the X-ray diffraction (XRD) manifested a broad peak of PAni and a cubic structure of cobalt manganese ferrite having crystal size between 60 nm and 138 nm, which decreases with increasing concentration of Mn. The field emission scanning electron microscopy (FE-SEM) images evidenced that the PAni has nanofiber (NF) structures, according to the method of preparation, where the hydrothermal method was used. The magnetic properties of the prepared ferrite, as well as the prepared PAni/Co_1-xMn_xFe₂O₄ composites, were studied through the vibrating sample magnetometer (VSM) analysis, where the magnetic hysteresis loops of ferrite elucidated a significant influence on the manganese content and the decorated PAni, through the decrease of both saturation magnetism (M_s) and remnant magnetism (M_r) in addition to the corrosive field (H_c). Increasing the content of manganese in the composites led to an improvement in the energy storage performance of the capacitors, which were tested in 1 M of H₂SO₄ by using the cyclic voltammetry analysis, galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Increasing the manganese content caused an increase in the specific capacity and a significant increase in the charging and discharging time; the highest capacitance is 556 F/g.