Facile Growth of Caterpillar-like NiCo2S4 Nanocrystal Arrays on Nickle Foam for High-Performance Supercapacitors

Ternary cobalt nickel sulfide as a novel and efficient electrode material in supercapacitors has recently gained extensive interests. Herein, we first report a highly conductive caterpillar-like NiCo2S4, compbsed of NiCo2S4 nanosheet core and nanowire shell grown on Ni foam via a facile and cost-effective chemical liquid process. Growth mechanism of the NiCo2S4 nanosheets@nanowires (NSNWs) structure was also investigated in detail by analyzing time-dependent experimental as well as the amount of additive ammonium fluoride in solution. Furthermore, the electrochemical measurements were performed among three different morphologies of NiCo2S4 including nanosheets, nanosheets@nanoparticles, and NSNWs structure, which were obtained from different reaction stages. Because the NSNWs structure has relatively high electroactive surface area, conductivity, and effective electron transport pathways, the asprepared NiCo2S4 NSNWs structure comparing with two other morphologies exhibits the maximum specific capacity of 1777 F/g at I A/g and the highest capacitance retention (83% after 3000 cycles) at a high scan rate of 10 A/g with a Mass loading density of 4.0 mg/cm(2). These results indicate that the NiCo2S4 NSNWs structure has great potential in supercapacitors.