A novel 3D MnNi2O4@MnNi2S4 core-shell nano array for ultra-high capacity electrode material for supercapacitors

Abstract In this work, a novel 3D MnNi2O4@MnNi2S4 core-shell nano array was successfully grown on nickel foam (NF) via in-situ growth method, which omitted the addition of binder and conductive additive and the complicated electrode preparation process. The MnNi2O4@MnNi2S4 possesses a unique nanorod@nanosheet core-shell structure, which can provide abundant active sites near the electrode interface for rapid electrochemical reaction, so the MnNi2O4@MnNi2S4 electrode materials exhibit high specific capacitance and excellent electrochemical properties. It is worth noting that the specific capacitance of the MnNi2O4@MnNi2S4 reaches 3578.57 F g−1 at the current density of 1 A g−1, and 1009.52 F g−1 at the current density of 20 A g−1. When the current density is 15 A g−1, the specific capacitance retention rate reaches 93.1% after 5000 cycles, showing good cycling performance. Moreover, the MnNi2O4@MnNi2S4//AC asymmetric device also exihibits low leakage current and excellent self-discharge characteristics. So, the MnNi2O4@MnNi2S4 is an excellent electrode material for supercapacitors.