Dual-material synergy in CuMn2O4@CuMn2S4 core-shell nanostructures: Towards high energy density supercapacitors

Transition metal oxides (TMOs) and sulfides (TMSs) have garnered significant attention as promising electrode materials for supercapacitors due to their complementary properties, including high conductivity, abundant active sites, and structural stability. The rational design and facile synthesis of TMO-TMS hybrid materials with unique architectures are critical to achieving high-performance energy storage devices. This study presents a novel CuMn2O4@CuMn2S4 core-shell nanostructure developed on a nickel foam substrate through hydrothermal and sulfurization processes. The CuMn2O4 core offers robust structural support and high conductivity, while the CuMn2S4 shell enhances electrochemical activity and ion diffusion. The synthesized material, CuMn2O4@C- uMn2S4 NF-2, achieved a specific capacitance of 760.5 F & sdot; g- 1 at 1.0 A & sdot;g-1, demonstrating superior electron transfer resistance (Rct=2.06 Omega ) and excellent cycling stability, retaining 85.2 % of capacitance after 5000 cycles. Furthermore, an asymmetric supercapacitor (ASC) with CuMn2O4@CuMn2S4 NF-2 as the positive electrode and activated carbon as the negative electrode delivered a maximum energy density of 35.31 Wh & sdot;kg- 1 at a power density of 750 W & sdot;kg-1 and retained 75.5 % capacitance after 5000 cycles. This study underscores the significant potential of integrating oxide and sulfide materials in a single architecture, offering a promising pathway for designing high-performance energy storage systems that capitalize on the synergistic properties of both material types.