Preparation Of Transition Metal Chalcogenides And Investigation Of Supercapacitor Performance

The super capacitor is a device that can convert chemical energy into electrical energy,and has the characteristics of long cycle life,high power density,low maintenance cost,and environmental protection.Transition metal compounds electrode materials have attracted attention due to their high specific capacity and stable cycle performance.This article mainly focuses on preparation nanostructured Cu,Ni,Cd chalcogenides and investigation of their supercapacitor performance:The Cu?OH?₂ nanowire structure was prepared by in-situ etching of copper substrate.The influence of etching time on the microstructure of the product was investigated.When the reaction time was 30 min,homogeneous and dense Cu?OH?2 nanowire structures with a length of about 4.6?m and a diameter of about 330 nm can be obtained on the copper surface.The results of electrochemical tests show that the specific capacitance of Cu?OH?2 nanowires is the highest.The specific capacitance could reach 750 F g^-1.In addition,a self-assembled Cu2O hollow sphere structure was prepared using a simple one-step hydrothermal templateless method.The diameter of the sphere was about 2.5?m,and it is consisted of nanosheets with a thickness of 50 nm.The structure of the hollow sphere makes the utilization of the active material improved,and display excellent supercapacitor performacne.Under the current density of 5 mA cm^-2,the electrode displays specific capacitance of 1075 F g^-1.The S and Se elements of the same family as the O are attracting more and more attention because their corresponding transition metal compounds exhibit excellent supercapacitor performance due to their good electrical conductivity.Still using the in-situ etching method,CuxS?1<x<1.92?was grown directly on the surface of the copper foam as a supercapacitor electrode without conductive agent and binder.The results of SEM and XRD indicate that the active material is composed of Cu_1.92S nanorods with a diameter of 280 nm and CuS nanobelts with a diameter of 80 nm.It is generally believed that the synergistic effect of the composite material will show better energy storage properties than that of a single-component electrode material,the hierarchical nanostructures also increase contact area of the material and the electrolyte.These features make the good electronic conductor CuxS electrode has excellent supercapacitor performance.When the current density is 5 mA cm^-2,the specific capacitance achieves 1122 F g^-1,and even after 10000 charge-discharge cycles,the specific capacitance could retain 85%of the initial value.Additionly,the supercapacitors performance of Cu2Se was studied.The?-Cu2Se was grown directly on a nickel foam substrate by one-step solvothermal method.By characterization of SEM,XRD,TEM,the nucleation and growth process of?-Cu₂Se was studied at different reaction time,and the supercapcitor performance is investigated systematically.Nickel-based supercapacitor electrode materials have been extensively studied and have an high specific capacitance.By rationally constructing nanostructures,it is an effective strategy to further improve its energy storage performance.For the first time,ZnO was used as a pore-forming agent to creat a pore structure with a diameter of approximately 6 nm on ultrathin Ni?OH?₂ nanosheets directly grown on nickel foam,a specific surface area is 68.4 m²g^-1.The interdigitated nanosheet provides rich channels for ion diffusion,and the porous structure increases the utilization of the active material,allowing the electrode to exhibit excellent charge storage ability even at a load of up to 10 mg.The specific capacitance is2258 F g^-1 under current density of 5 mA cm^-2,which could be still 900 F g^-1 even when the current density is increased to 100 mA cm^-2.The core-shell structure of NiOOH are also been constructed.The in-situ etched Cu?OH?2 nanowires on copper foil are used as core materials.Then,NiOOH with thickness of 80 nm is loaded on the surface of Cu?OH?₂ nanowires by chemical deposition.This three-dimensional Cu?OH?2@NiOOH shell-core structure can greatly increase the contact area between the electrode and the electrolyte.The core material provides rapid electron transfer and the shell material supplies large number of redox reactions.,which shows 2609 F g^-11 at current density of 10 mA cm^-2.Cadmium hydroxide has a wide range of applications in the battery field.Cd?OH?₂ has also been reported to have excellent supercapacitor performance,but there is not reports about application of CdS for supercapacitor.A simple hydrothermal method was used to grow CdS microspheres with a diameter of about 2?m directly on the nickel foam,and it was formed by stacking of 5 nm nanoparticles.The inherently good conductivity and porous structure ensure good electrochemical performance of the electrode:909 F g^-1 at current density of 2 mA cm^-2.