Enhanced capacitive performances and excellent stability of cadmium-sulfide-concealed nickel sulfide (Ni3S2/CdS) for electrochemical capacitors

Active materials with distinct structures significantly influence the electrochemical properties of supercapacitors. Herein, hierarchical cadmium-sulfide-concealed nickel sulfide (Ni3S2/CdS) nanostructures have been successfully grown on nickel foam using hydrothermal synthesis followed by successive ionic layer adsorption and reaction deposition. The resulting Ni3S2/CdS electrode exhibited a high specific capacity (545.6C g−1 at 1 A g−1) and outstanding cycling stability (capacity retention of 103% after 5000 charge-discharge cycles at a current density of 5 A g−1). This is because of the combined synergistic advantages of Ni3S2 (high specific capacity) and CdS (superior mechanical stability). Furthermore, a hybrid supercapacitor assembled using the Ni3S2/CdS cathode and an activated carbon anode showed a notable specific capacitance of 109 Fg-1 at 1 A g−1 and a capacitance retention of 110% after 5000 cycles, signifying excellent long-term cycling life. The hybrid supercapacitor exhibited a significantly high energy density of 34 Wh kg−1 with the power density of 748.8 W kg−1 at the current density of 1 A g−1. The above results suggest that the Ni3S2/CdS bilayer can be a prospective candidate for supercapacitors.