Synthesis of the Urchin-Like NiS@NiCo2S4 Composites on Nickel Foam for High-Performance Supercapacitors

A simple hydrothermal treatment process was used to prepare urchin-like NiS@NiCo2S4 composites on Ni foam, which were then employed as binder-free and conductive-agent-free electrodes for pseudocapacitors. The as-synthesized composites have significant capacitive performance because of the novel porous structure. A specific capacitance up to 14.32 F cm(-2) was obtained at a current density of 5 mA cm(-2), which was far higher than that of pristine NiCo2S4 nanotube arrays (about 8.4 F cm(-2)). More importantly, Ni@NiS@NiCo2S4 and activated carbon (AC) were assembled as the positive and negative electrode, respectively, in an asymmetric supercapacitor, which possesses prominent performance. In addition to 78.7 % capacitance retention when cycling at 50 mA cm(-2) for 5000 cycles, the as-fabricated Ni@NiS@NiCo2S4//AC device exhibits a high energy density of 38.96 Wh kg(-1) and power density of 339.62 W kg(-1) at a current density of 10 mA cm(-2).