Study On The Preparation Of Ni-Co Bimetallic Sulfide And Their Properties Of Supercapacitors

In recent years,supercapacitors have attracted much attention from many researchers due to their excellent characteristics such as high power density,long working life,fast charge and discharge speed and low maintenance cost.Compared with traditional batteries,the low energy density is a disadvantage that supercapacitors can not be ignored,and electrode materials are one of the key factors that affect their electrochemical performance.Therefore,research and preparation of excellent electrode materials have become the key to enhance the electrochemical performance of supercapacitors.Compared with many electrical materials,bimetallic sulfides are considered as electrode materials with great potential because of their high electrical conductivity and abundant chemical reaction.In this paper,nickel-cobalt sulfide is mainly used as the research object.Co Ni₂S₄powder,Co Ni₂S₄/carbon fiber cloth（CC）and Co Ni₂S₄@Ni S with different morphologies were successfully prepared and used as electrode materials to test and explore the improvement of electrochemical performance.The main research contents are as follows:（1）Preparation of Co Ni₂S₄materials with different morphologies:Co Ni₂S₄with different morphologies can be synthesized by changing the concentration of sulfur source.The crystal form,morphology and element distribution of the resulting products were characterized by XRD,EDS,XPS,SEM,TEM and other characterization methods Characterization.The influence of the amount of sulfur added on the morphology and electrochemical performance of the material was investigated.The Co Ni₂S₄electrode material with the best performance has a specific capacitance of 944 F g^-1at 1 A g^-1and a retention rate of 75.64%at 10 A g^-1.After5000 cycles,the specific capacitance retention rate was 91.1%.（2）Using carbon fiber cloth as the base material,Co Ni₂S₄nanoparticles were directly grown on the carbon fiber cloth by hydrothermal method and solvothermal method,and Co Ni₂S₄/CC electrode material was successfully prepared.The nanoparticles are finely and uniformly distributed on the carbon cloth,and the finely and uniformly distributed particles can provide more reactive sites.Under the same conditions,Co Ni₂S₄nanoparticles grown directly on carbon cloth have an outstanding specific capacitance of 1165 F g^-1at 1 A g^-1,which is 27.2%higher than the pure powder Co Ni₂S₄electrode material.The specific capacitance after charging and discharging 10000 cycles is 87.1%.It also has excellent rate performance(retains75.3%at 10 A g^-1).After the material is assembled into a flexible asymmetric supercapacitor Co Ni₂S₄/CC//r-GO,when the power density reaches 800W kg^-1,the energy density is 33.2 Wh kg^-1.（3）Ni S nanoparticles were directly grown on the Co Ni₂S₄/CC by electrodeposition method,and Co Ni₂S₄@Ni S electrode material was successfully prepared.The Co Ni₂S₄@Ni S composite material has an excellent specific capacitance of 1433 F g^-1at 1 A g^-1.At a current density of 10 A g^-1,its specific capacitance remains 69.6%.After assembling Co Ni₂S₄@Ni S//r-GO asymmetric supercapacitor,the specific capacitance of the device can reach 103.43 F g^-1when the current density is 1 A g^-1.The assembled device showed a maximum energy density of 36.6 Wh kg^-1at 800 W kg^-1.After 10000 charge-discharge cycles at a current density of 10 A g^-1,the device maintained an initial capacitance of approximately 78.7%.After assembling it into a solid electrode device,the small light bulb can be lit.