Design and synthesis of 3D hierarchical NiMoS₄@CuCo₂S₄ array electrode with excellent electrochemical performance

Large capacitance energy storage materials have a great application prospect due to the development of portable devices. An electrochemical deposition method was used to combine amorphous CuCo₂S₄ with NiMoS₄, which was prepared by a two-step hydrothermal method. The resulting grass-like nanowire array structure greatly promotes the utilization rate of active materials. By the addition of two variable valence metal ions, there is an increase in electrolyte touchable active sites and a decrease in the impedance of the electrode materials. Compared with bare NiMoS₄, the binder-free composite electrode has a significantly better capacitance characteristic. In particular, the NiMoS₄@CuCo₂S₄-8 has excellent capacity performance with a specific capacitance of 13.14 F cm^-2 at the current density of 5 mA cm^-2. The electrode shows 73% capacitance retention after 2000 charge-discharge cycles. It is shown that the combined effect of the nanowires and the several variable valence metal ions is effective to increase the specific capacitance of bimetallic sulfides.