A 3D petal-like Ni3S2/CoNi2S4 hybrid grown on Ni foam as a binder-free electrode for energy storage

In this study, a simple and one-pot synthesis method is developed to prepare a three-dimensional petal-like Ni3S2/CoNi2S4 hybrid material which can be used as a binder-free electrode in electrochemical energy storage. This material possesses a high areal capacity, such as 758 μA h cm−2 at a current density of 2 mA cm−2. With a 20-fold current density increase, the as-prepared material retains 70% of its original capacity. Furthermore, an asymmetric supercapacitor is assembled by using the Ni3S2/CoNi2S4 hybrid as the cathode and active carbon as the anode in a coin cell. This cell exhibits an outstanding areal power density of 31.212 mW cm−2 at an areal energy density of 0.288 mW h cm−2 and still retains a quite high areal power density of 3.876 mW cm−2 at an areal energy density of 0.364 mW h cm−2. These results show that the 3D petal-like Ni3S2/CoNi2S4 hybrid is a promising cathode material for practical application in energy storage.