Designs,Synthesis Of Nickel-based Composites For The Application In Supercapacitors

With the rapid development of global economy and the aggravation of environmental pollution,energy depletion has become one of the major problems we are facing today.This situation has triggered the research on the development and utilization of new energy.As a new type of energy conversion storage device,supercapacitor has attracted wide attention because of its advantages such as high specific capacity,fast charging and discharging speed and high environmental protection.The development of supercapacitors is closely related to electrode materials,and the morphology and structure of electrode materials directly affect the performance of supercapacitors.Nickel-based material composites have become a promising electrode material due to their high specific capacity,multiple layered nanostructures,low cost and environmental friendliness.However,their high internal resistance limits their application value in the field of electrochemistry.In this paper,a variety of compounds based on nickel-based materials were studied.The internal resistance was effectively reduced by compounding or curing nickel-based materials,and the unique advantages of nickel-based materials were elaborated by exploring their phase structure,micro structure and electrochemical properties.The main research contents can be summarized as follows:The urchin-like NiS@NiCo2S4 composite material with porous structure was synthesized on foam nickel by hydrothermal method.The operation method is simple and efficient,and the composite material prepared has good electrochemical performance.Electrochemical tests show that the energy density and power density of the two-electrode system,which was composed of sea urchin-like Ni@NiS@NiCo2S4 composite and activated carbon as positive and negative electrode materials,reached 38.96 Wh·kg-1 and 339.62 W·kg-1 at a current density of 10 mA·cm-2,respectively.And after 5000 cycles of life test under current density of 50 mA·cm-2,the capacitance retention rate can still reach 78.7%.It has good electrochemical stability and can work for a long time.The NiMoO4@Ni3S2 composite material was synthesized by hydrothermal method,and the influence of adding different amounts of ethylene glycol in the precursor solution on the morphology and electrochemical performance was investigated.Finding the best morphological structure and best electrochemical performance from scanning electron microscope SEM,transmission electron microscope TEM,X-ray powder diffraction(XRD)and a series of electrochemical tests.The results show that when the amount of ethylene glycol is 10 mL,the synthesized NiMoO4@Ni3S2 composite has the best electrochemical performance.The specific capacity reaches 870 C g-1 at a current density of 0.6 A g-1.Ni3S2 nanosheets were synthesized on foam nickel by hydrothermal method,and NiCo2O4 nanosheets were loaded on the surface of Ni3S2 by electrochemical deposition to prepare a core-shell structure Ni@Ni3S2@NiCo2O4 nanosheet with abundant electrochemically active sites.The prepared Ni@Ni3S2@NiCo2O4 electrode has a specific capacitance as high as 13.4 F cm-2 at a current density of 1 mA cm-2,and the assembled Ni@Ni3S2@NiCo2O4//AC ASC hybrid supercapacitor device has a capacitance of 5.783 F cm-2 at a current density of 2 mA cm-2,and a power density of 57 Wh·kg-1 at an energy density of 3700 W kg-1.which indicates that the material has broad prospects as a high-performance supercapacitor electrode.