Fabrication NiCo₂S₄/Co₉S₈ composites as a promising electrode material for supercapacitors

The series of the nonstoichiometry transition metal sulfides (TMSs) composites were fabricated by hydrothermal route. NiCo2S4/CogSg-3h shows a superior specific capacity (2532.5 Fg(-1) at 1 Ag-1) and 81.9% capacitance retention at 10 A g(-1). Moreover, the assembled NiCo2S4/CogSg-3h//active carbon (AC) device exhibits a high energy densit of 32.9 Wh kg(-1) at 750.6 W kg(-1) and outstanding capacitance retention of 94.7 % after 10000 cycles.