Microflower-like nickel sulfide-lead sulfide hierarchical composites as binder-free electrodes for high-performance supercapacitors

Nickel sulfide (NiS), lead sulfide (PbS) and composite of NiS-PbS hybrid are deposited onto nickel (Ni) foam current collector via a simple and cost-effective chemical bath deposition route and utilized as a binder-free battery-type electrode materials for supercapacitor applications. High-performance NiS and highly-stable PbS electrodes are rationally designed to develop a new class NiS-PbS electroactive material. Surface morphological and structural studies indicate that the NiS-PbS composite exhibits a beautiful morphology of nanosheet based microflower structures. Such hierarchical microflower structures provide abundant Faradic active sites and enable the fast redox reactions. As result, the NiS-PbS composite exhibits a higher specific capacity of 125.89 mA h g(-1) at a current density of 2 A g(-1) in 3 M KOH electrolyte solution, and it is 1.62 and 2.67 times higher than the bare NiS and PbS electrodes. In addition, NiS-PbS composite delivers excellent cycling stability retaining 88.97% of initial capacitance after 3000 cycles, which is much larger than that of NiS (76.86%) and PbS (82.72%) electrodes. Our results demonstrate that the microflower structured NiS-PbS composites are promising for supercapacitor applications.