Tailoring Zinc Ferrite With Mg and Mn: Dual Dopant Synergy for Hybrid Energy Storage Supercapacitor Devices

ABSTRACT Doping ZnFe 2 O 4 with Magnesium (Mg) and Manganese (Mn) promotes beneficial defects by tuning the bandgap and enhances the electronic conductivity, along with improvement in the electrochemical performance. Incorporating these dopants optimizes the crystal structure and provides additional active sites, leading to a superior rate capability and improved charge storage capacity compared to pristine ZnFe 2 O 4 for the supercapacitors (SCs). Zn (1− x ) Mg x Fe (2− x ) Mn x O 4 (ZMFMO), with x = 0.00, 0.05, and 0.10, was synthesized using the sol–gel autocombustion technique and confirmed with the physical characterizations, including the detailed X‐ray diffraction (XRD), Raman and UV–visible spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X‐ray spectroscopy (EDX) analysis. Brunauer–Emmett–Teller (BET) isotherms were analyzed, which show the impact of doping on the surface area. The electrochemical performance of the prepared symmetric coin cell and three‐electrode system was explored using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charging and discharging (GCD) studies. The three‐electrode characterization suggests high specific capacitance ( C sp ) of 121.5, 130.2, and 162.5 F g −1 for ZMFMO_00, ZMFMO_05, and ZMFMO_10, respectively, while the C sp was found to be 34.8, 36.4, and 47.3 F g −1 at 1 mV s −1 for ZMFMO_00, ZMFMO_05, and ZMFMO_10 in symmetric coin cells, respectively. It also shows excellent charge–discharge characteristics with a 23.9, 28.6, and 43.6 s discharging time for ZMFMO_00, ZMFMO_05, and ZMFMO_10, respectively, at 392 mA g −1 . It illustrates the energy and power density 5.01, 5.08, 8.19 Wh kg −1 and 29.52, 28.09, 28.11 W kg −1 at 39 mA g −1 for ZMFMO_00, ZMFMO_05, and ZMFMO_10 symmetric coin cell devices, respectively. Ex situ XRD analysis was performed to check the electrode stability after long‐term cycling. The results indicated that the developed doped nanomaterial exhibits excellent charge storage characteristics, followed by an LED light demonstration.