Preparation And Capacitive Properties Of Tungsten Oxide And Its Composites

Energy has always been the key driving force supporting social evolution and scientific and technological progress,as well as the most basic condition for economic development.Therefore,it has received continuous attention in many research fields and become an ever-renewed hot topic.Among them,non-renewable fossil energy such as coal,oil and natural gas occupies the dominant position and plays an important role.However,due to its non-renewable,easy to cause environmental pollution and other shortcomings,the current energy crisis can not be ignored,but also limit the further development of economic life.Therefore,the development of clean and renewable new energy system becomes particularly important.Among them,energy storage equipment is one of the most promising and important environmental protection technologies,which has a significant impact on the improvement of human civilization and living standards.Specifically,supercapacitor is an efficient energy storage device,which can maintain high energy density and power density levels at the same time,and has a long working life,so it is considered as a promising and potential method for storing electricity.The most direct and critical factor affecting the electrochemical performance of supercapacitors is the performance of electrode materials,which makes electrode materials a hot issue that has been widely concerned and studied.In this paper,relevant electrode materials are prepared by hydrothermal method and electrodeposition,and their structural characterization and electrochemical performance test are carried out.The main research includes the following two parts:1.Tungsten oxide electrode with good electrochemical activity and charge storage ability was prepared by hydrothermal method.A series of WO₃electrodes were prepared by adjusting ammonium acetate concentration in precursor liquid,stirring time and hydrogen peroxide dosage to explore the best conditions for WO₃electrode preparation.The micromorphologies of the samples were characterized and analyzed by X-ray diffraction spectroscopy and scanning electron microscopy.In a three-electrode system,cyclic voltammetry and constant current charge-discharge test were used to study the capacitive properties of the samples.It is found that the structure of WO₃^aelectrode on the carbon fiber fabric substrate is columnar cuboid,and is regularly perpendicular to the substrate.Electrochemical test results show that it has high specific capacitance and cycle life.In the 0.5 mol/L sulfuric acid electrolyte,WO₃^aelectrode has the best capacitive properties,and the maximum area specific capacitance can reach 4.50 F/cm²at the current density of 10 m A/cm².2.A wide potential window polypyrrole and tungsten oxide composite electrode（PPy-WO₃）with the best capacitance performance was synthesized by electrodeposition.The effects of different scanning speeds on the morphology and charge storage performance of the composite materials were studied by changing the scanning speed.The composition and morphology of the samples were characterized by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy.In a three-electrode system,the electrochemical performance of the electrodes was studied by cyclic voltammetry,constant current charge-discharge test and electrochemical impedance spectroscopy.The PPy-WO₃^{20 m V/s}electrode has a three-dimensional wafer structure,showing high specific capacitance performance.At a current density of 1 m A/cm²,PPy-WO₃^{20m V/s}electrode exhibits a wide charge storage potential window of 1.4 V（between-0.9 and 0.5 V vs.SCE）and an excellent mass specific capacitance of 145.13 F/g.After 10000 times of charge and discharge,the composite electrode shows good cyclic stability.