Design of Co-Modified NiFe2O4 Spinel Ferrites for Supercapacitor Applications

Spinel ferrites have emerged as promising electrode materials for supercapacitors due to their high theoretical capacitance and fast redox kinetics. In this study, pristine NiFe2O4 and Co-modified NiFe2O4 were synthesized via a facile, cost-effective and scalable approach, followed by comprehensive structural and electrochemical characterization. Co-modification was associated with enhanced electrochemical performance, which may arise from changes in surface chemistry, redox-active species, morphology and electrode resistance. The NiFe2O4/200 mg Co electrode exhibited a specific capacitance of 236 F g–1 at 2 A g–1, compared with 148 F g–1 for pristine NiFe2O4 under the same measurement conditions. The Co-treated electrode retained approximately 92.1% of its initial capacitance after 5000 charge-discharge cycles in three electrode configuration and 89.3% retention in two-electrode system over the same cycle life. The device delivered a maximum energy density of 6.9 W kg–1 and a power density of 4999.2 W kg–1. These electrochemical results establish Co-modified NiFe2O4 as a promising electrode material for supercapacitor applications.