MoS2 mediated tuning of CuCo2S4–MoS2 nanocomposites for high-performance symmetric hybrid supercapacitors

Abstract

In this investigation, molybdenum disulfide (MoS₂) nanosheets, copper cobalt sulfide (CuCo₂S₄) nanomaterials, and MoS₂ incorporated CuCo₂S₄–MoS₂ nanocomposites were synthesized as electrode materials for hybrid supercapacitors. The concentrations of MoS₂ were varied and optimized for the synthesis of CuCo₂S₄–MoS₂ nanocomposites to improve their electrochemical properties for use in high-performance energy storage devices. The successful formation of CuCo₂S₄–MoS₂ nanocomposites was confirmed by powder XRD analysis, TEM imaging and X-ray photoelectron spectroscopy analyses. In a three-electrode system, compared to other synthesized electrode materials, the CuCo₂S₄–MoS₂ (80 : 20) nanocomposite with a 20 wt% concentration of MoS₂ demonstrated the highest specific capacitance of 1333 F g⁻¹ at 1 A g⁻¹ current density and 94% capacitance retention after 5000 charge–discharge cycles. Notably, in a symmetric two-electrode configuration, the optimized CuCo₂S₄–MoS₂ (80 : 20) nanocomposite also exhibited the highest specific capacitance of 670 F g⁻¹ at 1 A g⁻¹ current density and achieved an energy density of 33.5 W h kg⁻¹ at 600 W kg⁻¹ power density compared to that of other synthesized electrode materials. Finally, a prototype supercapacitor was assembled by utilizing the optimized CuCo₂S₄–MoS₂ (80 : 20) nanocomposite as an electrode material via a coin cell to light up an LED. Our findings demonstrate that incorporation of MoS₂ improves electrochemical performance and 20 wt% MoS₂ is the optimum concentration to significantly enhance the charge storage capacity, conductivity, and stability of CuCo₂S₄. The charge storage mechanism of the optimized nanocomposite in a symmetric two-electrode system was comprehensively discussed. The outcome of this investigation demonstrated that the optimized CuCo₂S₄–MoS₂ (80 : 20) nanocomposite with its high charge storage capacity, energy density, and excellent long-term stability can be used as an efficient electrode material for high-performance symmetric hybrid supercapacitors.