Design and synthesis of 3D hierarchical NiCo2S4@MnO2 core-shell nanosheet arrays for high-performance pseudocapacitors

We report on the development of 3D hierarchical NiCo2S4@MnO2 core-shell nanosheet arrays on Ni foam for supercapacitors. In our design, the highly conductive NiCo2S4 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 MnO2 materials, which can overcome the limited conductivity of MnO2 itself. Furthermore, the 3D NiCo2S4@MnO2 hybrid electrode can provide efficient and rapid pathways for ion and electron transport. These merits together with the elegant synergy between NiCo2S4 and MnO2 lead to a high areal capacitance of 2.6 F cm(-2) at 3 mA cm(-2) and good cyclic stability.