Fabrication of Amorphous Carbon-Coated Co₃O₄ (Co₃O₄@C) Composite and Its Enhanced Electrochemical Performance for Supercapacitor Electrodes

In this work, Co₃O₄@C composite electrode materials were successfully fabricated by coating amorphous carbon on Co₃O₄ nanorods. Electrochemical tests demonstrated that the Co₃O₄@C composite exhibited superior electrochemical performance compared with pure Co₃O₄, including larger capacitive response, higher specific capacitance, and more excellent rate capability and cycle stability. Specifically, the Co₃O₄@C composite delivered specific capacitances of 924, 830, 752, and 680 F g⁻¹ at current densities of 2, 5, 8, and 10 A g⁻¹, respectively, retaining 73.6% of its initial capacitance when the current density was increased from 2 to 10 A g⁻¹. After 2000 consecutive charge–discharge cycles, the capacitance retention of Co₃O₄@C reached 89.4%, which was higher than that of pure Co₃O₄ (85.3%). Moreover, the Co₃O₄@C composite possessed accelerated ion and electron transport kinetics compared with pure Co₃O₄. The enhanced electrochemical performance of Co₃O₄@C can be ascribed to the synergistic effect between Co₃O₄ and amorphous carbon, the improved electrical conductivity provided by the carbon component, and the protective role of the carbon layer in mitigating the agglomeration and structural degradation of Co₃O₄ during cycling. These findings suggest that the Co₃O₄@C composite is a promising electrode material for high-performance supercapacitors.