Electrodeposited binder-free Cu-Mn-S nanosheets for high-performance asymmetric supercapacitor devices

In this study, three-dimensional interconnected nanosheet-like binder-free Cu-Mn-S@NF composites were efficiently fabricated on nickel foam by one-step electrochemical deposition and optimized for metal ion deposition concentration to improve the problem of electrochemical performance degradation due to volume expansion of supercapacitor electrode materials. Owing to the unique structure that provides many active sites and a stable skeleton structure that fully promotes the diffusion of ions from the electrolyte into the electrode material, the three-dimensional interconnected nanosheet Cu-Mn-S@NF electrode material exhibits excellent electrochemical properties, and the structure prevents agglomeration and volume expansion during charge/discharge cycles, alleviating active material shedding. Under the three-electrode system, Cu-Mn-S@NF exhibits excellent electrochemical performance with a high specific capacitance of 2468.8 F g⁻¹ at a current density of 2 A g⁻¹, and it still maintains a specific capacitance of 1940 F g⁻¹ at a high specific capacitance of 10 A g⁻¹, with a multiplier performance of 78.58%. The assembled Cu-Mn-S@NF//AC HSC can obtain a maximum specific capacitance of 153.1 F g⁻¹ (1 A g⁻¹), an energy density as high as 54.47 Wh kg⁻¹ at a power density of 800 W kg⁻¹, and 70.23% capacitance retention after 6000 cycles.