One of the most promising bimetallic sulphides for use in energy-storage systems is NiCo 2 S 4 , but further research is required to give it a high reversibility and electrochemical reaction capacity. In this study, we show the rational materials design of an ideal NiCo 2 S 4 nanoparticle as a NiCo 2 S 4 /RGO nanocomposite, embedded in a reduced graphene oxide (RGO) matrix. NiCo 2 S 4 nanoparticles, which ranged in size from 20 to 25 nm and were firmly fixed on the surface of RGO sheets, made up the produced composite. As predicted, the produced nanocomposite displayed a high specific surface area, a mesoporous structure, and high conductivity, resulting in a large electroactive area and rapid electron and ion motion. Additionally, we present the advancements in material science, showcasing the NiCo 2 S 4 /RGO nanocomposite electrode, which has a long cycle life of 5000 cycles, a high capacitance retention of 85.6 %, and an exceptional specific capacitance of 1505 Fg-1 at 1 Ag-1 . A high active-material loading asymmetric supercapacitor serves as an example of the real-world use. The NiCo 2 S 4 /RGO nanocomposite exhibits an exceptional 48 Whkg-1 energy density at a power density of 985 Whkg-1 , while maintaining a high power density of 7227 Wkg-1 density of 25 Whkg-1 . The exceptional stability and electrochemical efficiency of the NiCo 2 S 4 /RGO nanocomposite validate that our methodical materials science and technology optimisation in the areas of active substance synthesis, electrode expansion, and device design/ fabrication will help advance the development of high-performance supercapacitors in future years.