Designing a One-Pot Ternary Fe–Mn–Zn Oxide Positive Electrode with Enhanced Energy-Storage Properties for Hybrid Supercapacitors

In recent years, ternary metal-oxide nanocomposite-based active electrodes have been investigated more effectively for supercapacitor applications due to the existence of a greater number of electroactive sites and the synergistic effect of three different transition-metal ions. Herein, Fe–Mn–Zn oxide ternary nanocomposites are synthesized using a simple and cost-effective one-pot hydrothermal approach. The characterizations of XRD, FTIR, FESEM, EDX, HRTEM, and XPS are analyzed for the synthesized Fe–Mn–Zn oxide nanocomposites to study their phases, functional groups, morphologies, purity, and binding energies. The electrochemical characteristics for the developed electrodes are studied in a three-electrode technique using CV, GCD, EIS, and a cyclic stability test. As expected, the ternary nanocomposite electrode of Fe–Mn–Zn oxide reveals a maximum specific capacitance (C_spc1) of 1673.4 F/g in comparison to other developed electrodes of ZnFe₂O₄ (271.7 F/g) and ZnMn₂O₄ (412.7 F/g) at the appropriate scan rate of 10 mV/s. In addition, the Fe–Mn–Zn oxide ternary nanocomposite active electrode exhibits 2616.25 F/g of total capacitance (q_T^**), 686.94 F/g of outer capacitance (q_O^**), and 1929.30 F/g of inner capacitance (q_I^**) which are determined by Trasatti analysis. Moreover, the fabricated hybrid supercapacitor device provides a good specific capacitance of 320.8 F/g, a high energy density of 75.3 Wh/kg at the power density of 649.9 W/kg at 1 A/g of current density range, and 88.75% of superior capacitive retention over 10,000 cycles at 10 A/g. Therefore, a ternary metal-oxide nanocomposite electrode is proposed to be a promising material for energy-storage devices.