Design and Fabrication of Highly Porous 2D Bimetallic Sulfide ZnS/FeS Composite Nanosheets as an Advanced Negative Electrode Material for Supercapacitors

Metal sulfides delivered much better electrochemical performance over metal oxides due to the extended potential window with high conductivity and therefore are much investigated in the field of energy storage applications. Herein, binder-free two-dimensional bimetallic (ZnS/FeS) interconnected composite nanosheet arrays are synthesized on carbon cloth (2D-ZFS@CC) as an innovative negative electrode material for supercapacitors. The 2D-ZFS@CC exhibits improved capacitance (1367.5 F g–1/1641 C g–1 at 3 A g–1), rate-capability (58.5% at 10-fold high current density), and capacitance retention (87%) over bimetallic oxide (ZnFe2O4). This is accomplished by intelligently regulating the morphology to generate numerous pores with a wide accessible surface area and high porosity, which favors high capacitance, whereas the binder-free nature of the active material promotes fast charge transfer characteristics. Moreover, the kinetic analysis suggested that the 2D-ZFS@CC electrode stored charge based on the hybrid charge storage mechanism with b values of 0.70 and 0.72 for anodic and cathodic peaks, respectively. These results demonstrate the significant potential application of 2D-ZFS@CC as a negative electrode material for next-generation supercapacitor electrodes.