Lithium dopant assisted surface modification Zn ferrites for high-performance supercapacitor applications

Ferrite materials, such as Zn ferrites, show novel electrochemical properties. However, their low internal conductivity limits their usage in supercapacitor applications. Hence, developing an efficient strategy to improve the electrochemical properties of Zn ferrites has become a critical demand. Therefore, we introduce alkali metals, namely lithium, to induce the surface modification of Zn ferrites using the sol-gel-assisted combustion method. The X-ray diffraction (XRD) study has verified that the formation of cubic Li-doped Zn ferrites with hematite as a minor phase. The X-ray Photoelectron Spectroscopy (XPS) analysis establish that the LixZn1-xFe2O4 with x = 0.10 nanoparticles has a high hydroxyl group content with an inverse spinel structure. Li-doped Zn ferrites samples exhibit specific capacitance in decreasing order of x = 0.10 (898 F/g) > x = 0.05 (527 F/g) > x = 0.00 (42 F/g) at current density 2 A/g s in 6 M KOH. Furthermore, LixZn1-xFe2O4 with x = 0.10 displays good cycle life where it maintains around 80 % of its capacitance after 1000 charge-discharge cycles while retaining up to 66 % of its specific capacitance after 5000 cycles. It is worth noting that this electrochemical performance is among the highest values recorded for Zn ferrite-based materials for supercapacitor applications.