Direct Growth of NiCo2S4 Nanotube Arrays on Nickel Foam as High-Performance Binder-Free Electrodes for Supercapacitors

Arrays of NiCo2S4 nanotubes on nickel foam were prepared by means of a two-step method, and were directly applied as a binder-free supercapacitor electrode. Such a binder-free method enables intimate contact between the current collector and the active materials, and can effectively improve ion and charge transportation. As a result, the electrochemical performances of supercapacitors can be improved. The as-prepared NiCo2S4 nanotubes/Ni foam electrode shows a high specific capacitance (738Fg(-1) at 4Ag(-1)), excellent rate capability (78% capacitance retention at 32Ag(-1)), and good cycling stability (retention capacity of 93.4% after 4000cycles), which suggests its promising application for electrochemical capacitors.