The Preparation And Electrochemical Performance Research Of Ni-based Compound

Supercapacitors are currently attracting intensive attention because they can provide high power density,fast charge-discharge,long service life and non-polluting.Meanwhile,due to remarkable theoretical special capacity,good cycling performance and low cost,Ni-based nanostructure materials have been the subject of considerable research interests.Herein,we prepare Ni?OH?₂,NiO and NiS₂/NiO as supercapacitor electrode materials and investigate their electrochemical properties.At first,nanostructured?-Ni?OH?₂ with different morphologies are successfully grown on nickel foam using a template-free method by adjusting the anions of nickel salt precursors?NiSO₄·6H₂O,NiCl₂·6H₂O,Ni?NO₃?₂·6H₂O?.The morphology is examined by scanning electron microscopy and the phase structure is analyzed by X-ray diffraction?XRD?.The surface area is calculated with the Brunauer-Emmet-Teller?BET?model and the pore size distribution is determined with the Barett-Joyner-Halenda?BJH?method.The microstructure of?-Ni?OH?₂ remarkably depends on the nickel salt precursors including Ni?NO₃?₂,NiCl₂ and NiSO₄.The electrochemical behaviours of?-Ni?OH?₂ electrodes are investigated by cyclic voltammetry,galvanostatic charge/discharge test and electrochemical impedance spectroscopy in 6 mol dm^-3 KOH solution.Results show that the?-Ni?OH?₂/Ni-foam electrode prepared with NiSO₄ exhibits the largest specific capacitance(1025.3 F g^-1 at a current density of 1.0 A g^-1),best reversibility and lowest charge transfer resistance due to its largest porosity and surface area.Nanostructured NiO are prepared by calcining?-Ni?OH?₂/Ni-foam electrode and nanostructured NiS₂/NiO are successfully grown on nickel foam using a hydrothermal process.Nanostructured NiO electrode obtains the specific capacitance of 443 F g^-1 at 1 A g^-1.Meanwhile,the nanostructured NiS₂/NiO electrode exhibits exceptional capacitance performance with a high specific capacitance of 2251 F g^-1 delivered at current density of 1 A g^-1,while 1192 F g^-1 retained at 20 A g^-1.What's more,after 2000 cycles,the specific capacitance remains 1275 F g^-1(at 5 A g^-1)with a capacitance retention of 78%.Therefore,the NiS₂/NiO electrode shows exceptional electrochemical performance and has a promising future as high-performance supercapacitors.