Facile controlled synthesis of a hierarchical porous nanocoral-like Co3S4 electrode for high-performance supercapacitors

A facile one-step hydrothermal process is developed to synthesize a porous nanocoral-like Co3S4, which directly grows on a three dimensional (3D) macroporous nickel (Ni) foam. The scanning electron microscopy (SEM) images reveal the uniform formation of a Co3S4 nanocoral cluster on Ni foam with a hierarchical porous structure. The crystal growth mechanism and factors that influence the formation of the coral-like Co3S4 directly on Ni foam have been further studied. The subsequent electrochemical measurements demonstrate that the nanocoral-like Co3S4 as a binder-free electrode for supercapacitors possesses a large specific capacitance as high as 1559 F g−1 at a current density of 0.5 A g−1 in 2.0 M KOH aqueous electrolyte. Moreover, to confirm its practical application, an asymmetric supercapacitor is assembled with the nanocoral-like Co3S4 electrode as the positive electrode and activated carbon (AC) as the negative electrode. Such a device achieves a high energy density of 60.1 W h kg−1 at a power density of 418.2 W kg−1 and maintains 38.5 W h kg−1 at a high power density of 3812.5 W kg−1, suggesting that the presented nanocoral-like Co3S4 electrode not only has potential for applying in high energy density fields, but also in high power density applications.