Rational Design of Hierarchically Core-Shell Structured Ni₃ S₂ @NiMoO₄ Nanowires for Electrochemical Energy Storage

Rational design and controllable synthesis of nanostructured materials with unique microstructure and excellent electrochemical performance for energy storage are crucially desired. In this paper, a facile method is reported for general synthesis of hierarchically core-shell structured Ni₃ S₂ @NiMoO₄ nanowires (NWs) as a binder-free electrode for asymmetric supercapacitors. Due to the intimate contact between Ni₃ S₂ and NiMoO₄ , the hierarchical structured electrodes provide a promising unique structure for asymmetric supercapacitors. The as-prepared binder-free Ni₃ S₂ @NiMoO₄ electrode can significantly improve the electrical conductivity between Ni₃ S₂ and NiMoO₄ , and effectively avoid the aggregation of NiMoO₄ nanosheets, which provide more active space for storing charge. The Ni₃ S₂ @NiMoO₄ electrode presents a high areal capacity of 1327.3 µAh cm^-2 and 67.8% retention of its initial capacity when current density increases from 2 to 40 mA cm^-2 . In a two-electrode Ni₃ S₂ @NiMoO₄ //active carbon cell, the active materials deliver a high energy density of 121.5 Wh kg^-1 at a power density of 2.285 kW kg^-1 with excellent cycling stability.