Nickel Sulfide/Molybdenum Disulfide Nanocomposites Synthesized via a Sulfur Precursor-Free Hydrothermal Route for Supercapacitors and Sodium-ion Batteries

Supercapacitors and sodium-ion batteries (SIBs) are promising energy storage technologies because of their high power and energy densities, where electrode materials hold a pivotal role in determining the overall performance. In this work, NiSx/MoS2 nanocomposites are synthesized via a sulfur precursor-free hydrothermal method, utilizing 1T-MoS2 as both the template and sulfur source. The influence of nickel precursor concentrations on the morphology and electrochemical performance is systematically investigated for supercapacitor and SIB applications. The resulting NiSx/MoS2 nanocomposites exhibit uniform particle sizes and homogeneous morphology. Electrochemical characterization reveals that the NiSx/MoS2-0.25 nanocomposite unveils the maximum specific capacitance of 585.1 F/g at 1 A/g, outperforming both pristine 1T- and 2H-MoS2. The optimized composite is further utilized to construct an asymmetric supercapacitor, which displays admirable durability, holding 96% of its initial capacitance after 9000 cycles. Additionally, the NiSx/MoS2-0.25 nanocomposite is employed in SIBs as an anode material, demonstrating a reversible capacity of 560.3 mAh/g at 0.05 A/g. The charge storage mechanism and cycling stability are further evaluated by electrochemical analysis, confirming their excellent electrochemical performance and structural integrity over 100 cycles.