Hierarchical binder-free NiCo2O4@CuS composite electrodes have been successfully fabricated on a nickel foam surface using a facile hydrothermal method and directly used as a battery-type electrode material for supercapacitor applications. The surface morphological studies reveal that the composite electrode exhibited porous NiCo2O4 nanograss-like structures with CuS nanostructures. The surface area of the composite is significantly enhanced (91.38 m2 g-1) compared to NiCo2O4 (52.16 m2 g-1), with a predominant pore size of 3-6 nm. This synergistic combination enhanced the electrode's electrochemical properties. The NiCo2O4@CuS electrode delivered an impressive specific capacitance of 141.13 mA h g-1 at 1 A g-1, surpassing the performance of the bare NiCo2O4 electrode. The composite electrode also exhibited excellent rate capability and cycling stability, retaining 87.49% of its initial capacity at high current densities and 88.62% after 3000 cycles. A hybrid supercapacitor (HSC) device assembled using NiCo2O4@CuS and G-ink electrodes attained a peak energy density of 28.85 W h kg-1 at a power density of 238.2 W kg-1, outperforming many reported HSCs. Additionally, the HSC device demonstrated exceptional cycling stability, retaining 87.59% of its initial capacitance after 4000 cycles. The superior performance of the NiCo2O4@CuS composite electrode is attributed to the synergistic combination of NiCo2O4 and CuS, which promotes interfacial electron separation and facilitates rapid electron transfer.
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