NiCo2S4@graphene nanocomposites as high-performance cathode materials with enhanced rate capability for Lithium-ion batteries

In this study, we present the preparation and electrochemical performance (ECP) of NiCo₂S₄@graphene nanocomposites as high-performance cathode materials for lithium-ion batteries (LIBs). Hydrothermal synthesis in a single step was employed to fabricate the composite, enabling uniform anchoring of NiCo₂S₄ nanoparticles on the graphene matrix. Structural characterization using XRD, Raman spectroscopy, SEM, and BET investigation revealed the successful formation of the composite with a mesoporous architecture and improved surface area. Electrochemical testing revealed that the NiCo₂S₄@graphene electrode delivered a high initial discharge capacity (DC) of 113.4 mAh g⁻¹ at 0.1C, significantly surpassing 97.5 mAh g⁻¹ observed for pristine NiCo₂S₄. Under a high current rate (CR) of 5C the composite achieved 58.02 mAh g⁻¹, whereas the unmodified sample reached only 27.78 mAh g⁻¹, confirming its improved capability for fast charge and discharge. EIS showed a marked reduction in charge transfer resistance (R_CT) from 138 Ω (NiCo₂S₄) to 64 Ω (NiCo₂S₄@graphene), highlighting improved interfacial charge transport. Additionally, capacity retention after 30 cycles at various current rates was 95% for the composite, compared to 91% for pristine NiCo₂S₄. The enhanced electrochemical behavior stems from the integrated contribution of the interaction between the conductive graphene matrix and the redox-active NiCo₂S₄ nanoparticles, which together improve electron mobility, structural stability, and ion diffusion. This outcome underscores the suitability of NiCo₂S₄@graphene composites for high-performance LIB applications.