Tuning the Electrochemical Performance of Cu₂S/Co₃S₄ via Optimized CNT Incorporation for High Energy and High Power Supercapacitor Application

Transition metal sulfides are emerging as promising materials for supercapacitor applications due to their excellent conductivity, high theoretical capacities, and stability. Exploring these materials, along with enhancements like doping of carbonaceous materials, could lead to high-performance solutions that address the growing need for renewable energy technologies and sustainable energy storage systems. Herein, mixed metal sulfide Cu2S/Co3S4 composites with varying percentages of multiwalled carbon nanotubes (MWCNTs) were synthesized through a facile one-step hydrothermal method. The resulting materials displayed outstanding electrochemical behavior. This performance was optimized by tuning the weight percentage of CNTs doped in the metal sulfide scaffold. Among the prepared nanocomposites, i.e., Cu2S/Co3S4@CNT-x, referred to as CCS@CNT-x (where x is the wt % of CNT), CCS@CNT-10 showed the maximum specific capacitance (Csp) of 960 F g–1 at 1 A g–1 (specific capacity, Cs of 638 C g–1), as revealed from electrochemical measurements. The as-fabricated device CCS@CNT-10//activated carbon sustained a broad potential window of 1.7 V, showing a high power density of 17000 W kg–1 along with a high energy density of 68 Wh kg–1 at 20 A g–1. The device was able to maintain its cyclic stability up to 95% even after 20,000 cycles. The exceptional electrochemical performance of the device can be attributed to the synergistic interactions between Cu2S and Co3S4, combined with the highly conductive interconnected network created by CNT incorporation. This combination facilitates efficient redox reactions at the electrode–electrolyte interface and accelerates electron transport throughout the material.