Effect of Ni doping on the structural, magnetic, and electrochemical properties of BiMnFe2O6 for energy storage applications

In this work, novel BiMn_1-xNi_xFe₂O₆ electrode materials with x = 0, 0.05, 0.1, 0.2, and 0.3 were successfully prepared by the solid-state reaction method and characterized by XRD, SEM, BET, and VSM techniques. The influences of Ni doping on the structural, magnetic, and electrochemical properties of BiMnFe₂O₆ materials were studied for the first time, representing a new approach to develop multifunctional properties of this material. The evidence of Mn⁺³, Ni⁺² and Fe⁺³, and Bi³⁺ in the structure was confirmed by advanced synchrotron-based techniques, including X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS), respectively. Increasing Ni content resulted in improved paramagnetic behavior, with a maximum magnetization value of 6.77 emu/g at x = 0.3. The specific surface area of the prepared samples reached 1.89 m²/g at x = 0.3, resulting in a maximum specific capacitance of 209.3 F/g at a current density of 1 A/g. In addition, an asymmetric supercapacitor using AC//BiMn_0·7Ni_0·3Fe₂O₆ was developed, which achieved an energy density of 8.02 Wh/kg and a power density of 752.7 W/kg with a high charge–discharge stability of 88.7 % after 1000 cycles at 10 A/g. The results indicated that Ni-doped BiMnFe₂O₆ was a promising high-performance electrode material for practical application energy storage devices.