Exploring advanced CoFe2O4/NiO nanocomposites with tunable structural, electrical, and magnetic properties for electrochemical energy storage

This study investigates the properties of (1-x) CoFe₂O₄/(x)NiO $[0\le x\le 1;$ where x  = 0.00 (CFO), 0.25 (C7N2), 0.50 (C5N5), 0.75 (C2N7), and 1.00 (NiO)] nanocomposite, synthesized using facile sol–gel auto combustion method and optimizing their concentration for energy storage applications. High- resolution X-ray diffraction (HR-XRD) confirms the formation of crystalline phases with crystallite sizes ranging from 20-30 nm. The FT-IR and Raman analysis further verify the structural formation of the prepared nanocomposites. The porous nature has been observed via FESEM micrographs and the EDX confirms the presence of elements such as Fe, Ni, Co, and O in the prepared nanocomposite. BET analysis showed that the prepared nanocomposite (C5N5) exhibited the highest specific surface area, thus improving overall electrochemical performance. The dielectric permittivity enhanced with the corresponding rise in the NiO content in the CFO, indicating an improved charge storage capacity upon the addition of nickel oxide content. In addition, the conductivity values have also improved with the addition of nickel oxide. The nanocomposite (C5N5) exhibits minimum loss which ensures its usage in high frequency applications. Moreover, the magnetic saturation decreased with the addition of NiO in CFO nanoparticles and showed a transition from ferrimagnetic behaviour to antiferromagnetic behaviour. The Galvanic charge–discharge studies demonstrated that the composition, 50 %CFO-50 %NiO (C5N5) delivered a maximum specific capacitance of 202.84F/g at 1 A/g with excellent capacitance retention of 78.21 % over 5000 continuous charging/discharging cycles due to excellent conductivity and high surface area. The synergistic integration induced enhanced conductivity and magnetic responsiveness, enabling the prepared ferrites/oxides-based nanocomposites promising for the next-generation electrochemical energy storage devices. These findings indicate that a sample, synthesized nanocomposite (C5N5) keeps the potential to be used as electrode material in energy storage as well as in high-frequency applications.