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Porous NiCo₂S₄ networks have been successfully synthesized by a facile one-pot solvothermal method without the use of any surfactant or template. Crystal structure, morphology, composition and surface area of the as-synthesized samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy and Brunauer–Emmet–Teller techniques. Owing to their porous nature and small crystalline size, the as-prepared NiCo₂S₄ networks based supercapacitor electrodes showed a high specific capacitance of 1250F$\cdot$g${}^{-1}$ at 1A$\cdot$g${}^{-1}$, and excellent cycling stability with the retention capacity of 70.3% after 5000 cycles in the KOH aqueous solution electrolyte.

To improve the electrochemical performance of the supercapacitor, three electrode nanocomposites, NiO, NiS and NiCo₂S₄, have been obtained by simple hydrothermal process and high temperature pyrolysis, and further, the impact of electrolytes of different concentrations on electrochemical performance of supercapacitor has been researched. During the research processing, synergistic effect of Ni, Co and S is considered to enhance the electrical conductivity, and promote electron transfer, ion diffusion and structural stability. The experiment results show that bimetallic sulfides display high electrical conductivity, shorter ion diffusion channels, and faster electron and ion transport rate with the feature of topping electrochemical properties of specific capacity, excellent cycling stability and high rate capability, and besides show that it can improve the electrochemical performance of the material by increasing the concentration of electrolyte. The transition-metal sulfides provide a new promising pathway for the expansion of high-performance electrode materials for supercapacitors.

Supercapacitors require excellent cycling stability and rate capability for electrodes. The NiCo₂S₄ spinel structure has caught much attention for its high conductivity and high theoretical specific capacity. However, due to the lack of active sites, it has been restricted in supercapacitors. In this research, the NiCo₂S₄ nano-material with needle, sheet and porous network morphologies were prepared by the addition of different kinds of surfactants via a simple hydrothermal method. At 1mA/cm², capacitance of these NiCo₂S₄ nanomaterials is measured as 2.09F/cm², 3.22F/cm², and 4.42F/cm², respectively. It was found that the exposure ratio of (111) and (220) crystal facets also has an effect on electrochemical performance, and NiCo₂S₄ with I${}_{(111)}$/I${}_{(220)}$ of 3:1 showed better performance. Furthermore, NiCo₂S₄-PN//AC asymmetrical supercapacitor was assembled with NiCo₂S₄-PN serving as positive electrode and activated carbon (AC) as negative electrode. At a power density of 7.284mW/cm², energy density achieved was 0.625mWh/cm². Additionally, capacitance retention rate remained at 79.6% of initial capacitance after 1500 cycles. These outcomes are of great significance for developing more efficient, stable and reliable transition metal sulfide-based supercapacitors.