Design and synthesis of 3D hierarchical NiCo sub(2)S sub(4)nO sub(2) core-shell nanosheet arrays for high-performance pseudocapacitors

We report on the development of 3D hierarchical NiCo sub(2)S sub(4)nO sub(2) core-shell nanosheet arrays on Ni foam for supercapacitors. In our design, the highly conductive NiCo sub(2)S sub(4) nanosheets can serve not only as a good pseudocapacitive material, which can be contributed to the capacitance of the whole electrode, but also as a 3D conductive scaffold for loading MnO sub(2) materials, which can overcome the limited conductivity of MnO sub(2) itself. Furthermore, the 3D NiCo sub(2)S sub(4)nO sub(2) hybrid electrode can provide efficient and rapid pathways for ion and electron transport. These merits together with the elegant synergy between NiCo sub(2)S sub(4) and MnO sub(2) lead to a high areal capacitance of 2.6 F cm super(-2) at 3 mA cm super(-2) and good cyclic stability.