Research On Preparation And Electrochemical Performance Of Metal Compound Electrode Material With Array Structure

Supercapacitors are widely used in the driving systems of electronic circuits,national defense and new energy vehicles due to the high power density,good cycle stability and low cost.Besides the study on the energy storage characteristics of supercapacitors,the multifunction and intelligence of devices have gradually become the researcher focus.For example,electrochromic supercapacitors which integrate the electrochromic and supercapacitors,can produce color changes at different voltages to meet the needs of the environment and users.Whether for supercapacitors or electrochromic devices,electrode materials are the core of devices,and their microstructure influences the performance of devices.Transition metal compounds are often used as electrodes for electrochromic supercapacitors due to their high theoretical specific capacitance,abundant valence states,easily available and low cost.However,its low conductivity and easy agglomeration of transition metal compounds limit their electrochemical performance.Therefore,in this paper,we take the array structure with large specific surface area and good conductivity as the skeleton,and grow the transition metal compound materials on it,and prepare two kinds of composite electrodes,namely VOCNT@Co0.85Se/NF and TiO2@MnO2/FTO.the energy storage and electrochromic characteristics of the two kinds of composite electrodes are studied respectively,and two kinds of electrochromic supercapacitors are designed and assembled.The research work of this paper mainly includes:(1)preparation and electrochemical performance of vertical array carbon nanotubes/cobalt selenide(VOCNT@Co0.85Se/NF)composite electrode.The VOCNT was prepared by spray pyrolysis which does not need to deposit catalyst and oxide slow-release layer on the substrate in advance,which is simple in process and beneficial to large-scale preparation.The Co0.85Se nanoparticles are supported and dispersed by using VOCNT as a stable framework,which effectively prevents the collapse of the internal structure of the electrode.Compared with the single Co0.85Se/NF electrode material,the VOCNT@Co0.85Se/NF composite electrode shows excellent electrochemical performance.At the current density of lA/g,the specific capacitance of VOCNT@Co0.85Se/NF composite electrode reached 638 F/g.when the current density increased to 30 A/g,the specific capacitance remained at 87.8%of the initial capacitance.At the current density of 10 A/g,the capacitance of VOCNT@Co0.85Se/NF remains at 97%of the initial capacitance value after 5000 charge and discharge tests.(2)Preparation and electrochemical performance of TiO2@MnO2/FTO composite electrode.In this paper,TiO2 nanorod array skeleton and MnO2 nanosheets were grown on FTO by hydrothermal method to obtain TiO2@MnO2/FTO composite electrode.The electrochemical and electrochromic properties of single TiO2/FTO,MnO2/FTO and TiO2@MnO2/FTO matrix composite electrodes were studied by a three-electrode test system.The area specific capacitance of TiO2@MnO2/FTO is 14.5 mF/cm2 when the current density is 0.05 mV/s,which is higher than 5.9 mF/cm2 of MnO2/FTO.In the voltage range of 0-1 V,TiO2@MnO2/FTO composite electrode shows electrochromic characteristics at the same time,and its light modulation amplitude is 6.2%when the wavelength is 630 nm.The above results indicate that TiO2@MnO2/FTO composite electrode has both energy storage and color change functions.(3)Study on the assembly and performance of all-solid electrochromic supercapacitors.Two kinds of asymmetric electrochromic supercapacitors were assembled by hydrothermal preparation of MoO3 nanobelts and coating them on FTO as cathode,LiClO4-PEG as gel electrolyte,VOCNT@Co0.85Se/FTO electrode with energy storage characteristics and TiO2@MnO2/FTO composite electrode with energy storage and color change characteristics as anode.Test results show that the assembled VOCNT@Co0.85Se/FTO//MoO3/FTO and TiO2@MnO2/FTO//MoO3/FTO devices have the characteristics of energy storage.And under different voltages,the color of the device changes obviously,which shows that the assembled device has two functions of energy storage and color change.In addition,the light modulation amplitude of TiO2@MnO2/FTO//MoO3/FTO device reaches 21.2%at the wavelength of 700 nm.The results show that the light modulation amplitude of the dual-function device assembled by the principle of complementary color change is significantly higher than that of the single anode electrode TiO2@MnO2/FTO(6.2%).