Fabrication of (Ag, Zn, Co) based spinel ferrites as electrode materials for high energy density hybrid supercapacitors

Three spinel ferrites, AgFe2O4, CoFe2O4, and ZnFe2O4, were successfully synthesized using the hydrothermal technique and were employed as electrode materials for supercapacitor applications. These spinel ferrites underwent a comprehensive assessment of their crystallinity, morphology, and electrochemical performance. The structural analysis using X-ray diffraction convincingly demonstrated the excellent crystallization of these compounds, indicating the development of single-phase spinel ferrites. A uniform cubic structure was successfully achieved. TEM analysis revealed that the as-synthesized nanomaterials exhibited a spherical shape with particle sizes ranging from 50 to 100 nm. In terms of electrochemical performance, utilizing a three-electrode configuration, the cubic spinel CoFe2O4 nanoparticles, synthesized at 200 °C, exhibited outstanding results, with a maximum specific capacitance of 2146.40 F/g at 3 mV/s, surpassing the performance of AgFe2O4 and ZnFe2O4. To create a hybrid asymmetric device utilizing all three spinel ferrites, activated carbon served as the negative electrode, while AgFe2O4, CoFe2O4, and ZnFe2O4 were employed as positive electrodes. Notably, the CoFe2O4 electrode outperformed the others, achieving a remarkable 94 % coulombic efficiency and demonstrating long-term cyclic stability with 87 % capacitance retention after 10,000 cycles. The findings of this study underscore the significant potential of the synthesized nanoparticles as promising candidates for hybrid supercapacitors and various other electrochemical applications.