Designing\na One-Pot Ternary Fe–Mn–Zn\nOxide Positive Electrode with Enhanced Energy-Storage Properties for\nHybrid Supercapacitors

In\nrecent years, ternary metal-oxide nanocomposite-based active\nelectrodes have been investigated more effectively for supercapacitor\napplications due to the existence of a greater number of electroactive\nsites and the synergistic effect of three different transition-metal\nions. Herein, Fe–Mn–Zn oxide ternary nanocomposites\nare synthesized using a simple and cost-effective one-pot hydrothermal\napproach. The characterizations of XRD, FTIR, FESEM, EDX, HRTEM, and\nXPS are analyzed for the synthesized Fe–Mn–Zn oxide\nnanocomposites to study their phases, functional groups, morphologies,\npurity, and binding energies. The electrochemical characteristics\nfor the developed electrodes are studied in a three-electrode technique\nusing CV, GCD, EIS, and a cyclic stability test. As expected, the\nternary nanocomposite electrode of Fe–Mn–Zn oxide reveals\na maximum specific capacitance (<i>C</i><sub>spc1</sub>)\nof 1673.4 F/g in comparison to other developed electrodes of ZnFe<sub>2</sub>O<sub>4</sub> (271.7 F/g) and ZnMn<sub>2</sub>O<sub>4</sub> (412.7 F/g) at the appropriate scan rate of 10 mV/s. In addition,\nthe Fe–Mn–Zn oxide ternary nanocomposite active electrode\nexhibits 2616.25 F/g of total capacitance (<i>q</i><sub>T</sub><sup>**</sup>), 686.94 F/g\nof outer capacitance (<i>q</i><sub>O</sub><sup>**</sup>), and 1929.30 F/g of inner capacitance\n(<i>q</i><sub>I</sub><sup>**</sup>) which are determined by Trasatti analysis. Moreover, the\nfabricated hybrid supercapacitor device provides a good specific capacitance\nof 320.8 F/g, a high energy density of 75.3 Wh/kg at the power density\nof 649.9 W/kg at 1 A/g of current density range, and 88.75% of superior\ncapacitive retention over 10,000 cycles at 10 A/g. Therefore, a ternary\nmetal-oxide nanocomposite electrode is proposed to be a promising\nmaterial for energy-storage devices.