Optimization of the redox-active copper zinc sulfides with the integration of SWCNTs nanocomposites for the asymmetric supercapacitor

The supercapattery device, a renowned electrochemical energy storage system, combines a supercapacitor and a battery electrode, resulting in the device's impressive energy and power capabilities. These hybrid supercapacitors can meet the increasing energy demand by offering high energy density (E_d) and power density (P_d). Here, we synthesized mono and binary transition metal sulfides using hydrothermal techniques, including CuS, ZnS, and Cu_xZn_(1-x)S (with metals varying ratios 1:3, 1:1, and 3:1) nanoparticles, as well as nanocomposites of single-walled carbon nanotubes (SWCNTs) with Cu_xZn_(1-x)S (1:3, 1:1, and 3:1). The effective synthesis was validated through different structural and morphological advanced characterizations and confirmed the successful synthesis of the materials. The sample SWCNTs/C₃Z₁S, tested in a three-electrode configuration, showed better results, with a specific capacitance of 2280 F g−1 at a current density of 0.5 A g−1 across all six electrode configurations. Additionally, an asymmetric supercapacitor (ASC) device (SWCNTs/C₃Z₁S || AC) was fabricated, achieving an E_d of 66 Wh kg−1 and a P_d of 425 W kg−1 at a current density of 0.5 A g−1, tested in a two-electrode setup. The ASC also demonstrated a Coulombic efficiency of 99.5% and a capacity retention of 93.7% over 4000 cycles at the current density of 5 A g−1. Furthermore, the electrode material comprising (SWCNTs/C₃Z₁S) shows significant potential for advanced supercapacitor technology.