The Preparation And Electrochemical Performance Of Ni（OH）₂-based Nanoarray Supercapacitor Electrode Materials

As an electrode material for supercapacitors,cheap nickel hydroxide(Ni(OH)2,NH)nano-sheet materials have attracted much attention due to their high theoretical specific capacity and other advantages.However,the poor conductivity of the material seriously restricts its practical application.In order to make up for the defects of Ni(OH)2 nano-sheet materials,this work developed a series of core-shell heterostructure nanoarray electrode materials by using Ni(OH)2 nanosheet as the shell and different metal oxide or metal sulfide nanowire as the core.Owing to the increased electrochemical active sites,the Ni(OH)2 nanosheet based core-shell heterostructure nanoarrays exhibited significantly enhanced electrochemical properties.The microstructure,phase properties and stability of the prepared electrode materials were analyzed by various characterization methods,and their electrochemical properties were further studied.The specific research contents are as follows:1.NiCo2O4@Ni(OH)2 nanostructured electrode materials grown directly on nickel foam were successfully prepared by hydrothermal,calcining and electrodeposition methods.The crystal phase and microstructure of the samples were tested and analyzed by a series of characterization methods including XRD,SEM.,TEM and BET.At the current density of 1 A/g,the capacity of NiCo2O4@Ni(OH)2 reached 2218.0 F/g,and the capacitance remained at 96.4%after 5000 cycles.In addition,NiCo2O4@Ni(OH)2 was used as the positive electrode and activated carbon as the negative electrode to assemble the asymmetric supercapacitor.The supercapacitor exhibits excellent electrochemical performance,with an energy density of 98.5wh/kg at a power density of 800 W/kg.At the same time,two supercapacitors can be connected in sernes to successfully light a white LED light.2.A new type of sea urchin Co9S8@Ni(OH)2 core-shell nanostructured array electrode material was successfully synthesized by hydrothermal method and electrodeposition method.The phase and structure of the prepared sample were tested and analyzed by XRD,BET,XPS and other characterization methods.The electrochemical properties of Co9S8@Ni(OH)2 electrode materials were tested and analyzed.When the current density were 1 A/g and 10 A/g,the specific capacitance were 2513.5 F/g and 1531.7 F/g,respectively.After 5000 cycles,the retention rate of initial specific capacitance was 98.6%(the current density was 10 A/g).In addition,the Co9S8＠Ni(OH)2 asymmetric supercapacitor was successfully assembled.When the power density was 800 W/kg,the energy density of the supercapacitor reached 48 W/kg.The capacitance retention rate reached 93.5%after 2000 cycles.By connecting the two supercapacitors in series,the LED white light can be successfully lit.3.Core-shell nanoarray Coo-Ni(OH)2 electrode materials were prepared by hydrothermal,calcining and electrodeposition methods.The phase,morphology and microstructure of the electrode materials were analyzed by XRD.,TEM and XPS.CoO-Ni(OH)2 has certain advantages in terms of components and structure.Electrochemical tests show that the material had high specific capacitance of 1395.82 F/g and 830.27 F/g when the current density is 1 A/g and 10A/g,the retention rate of the capacitance after 5000 cycles is 93.7%,indicating good cycling stability.The asymmetric supercapacitor was assembled with Coo-Ni(OH)2 as the positive pole and activated carbon as the negative pole.When the power density was 800 W/kg,the energy density of the supercapacitor was as high as 92.47 Wh/kg.After 2000 cycles,the capacitance retention rate reached 87.4%.