Synthesis of nanostructured metal sulfides via a hydrothermal method and their use as an electrode material for supercapacitors

Metal sulfides have attracted considerable interest owing to their notable electrochemical properties and multiple application areas, such as solar cells and supercapacitors (SCs). This paper describes the design and synthesis of nickel foams decorated with different metal sulfides, such as CoS/NF, CuS/NF, FeS/NF, and NiS/NF electrodes for SCs. The FeS/NF coral reef-like nanostructure exhibited outstanding electrochemical performance in SCs with a high specific capacitance (2007.61 F g(-1) at 2 A g(-1)), good cycling stability (only 3% loss after 3000 cycles at 2 A g(-1)), excellent rate capability (52.27% capacity retention at 20 A g(-1)), and higher energy density (54.88 W h kg(-1) at a power density of 500 W kg(-1)) compared to other electrodes. The elevated performance of the FeS/NF was attributed mainly to the coral reef-like nanostructure with a relatively high specific surface area, which offers a large interfacial area between the electrode and electrolyte and sufficient physical cavities for rapid ionic diffusion. These results suggest that the coral reef nanostructure can be used not only in large energy density applications, but also in large power density fields, such as energy storage devices, flexible electronics, and electric vehicles.