Preparation And Properties Of Vanadium Pentoxide Based Electrochromic Ionic Storage Films

Electrochromic devices have been shown great prospect of application in "smart windows", anti-glare mirrors and information display devices, etc. Especially in recent years, with the development of low-carbon economies, the research and application of transmitting electrochromic devices have developed rapidly. With electrochromic "smart windows" as the research object, this paper has analyzed the structures and features of transmitting electrochromic devices in detail. We have proposed that V2O5 modified by compositing with transition metal oxides, and used as the ion storage layer of devices. Improving the ion storage capacity and optical modulation of V2O5, in order to provide a theoretical and expermental basis for the application of electrochromic "smart windows".In this paper, V2O5-TiO2 composite ionic storage electrode films were successfully prepared by the modified inorganic sol-gel route. The structure and properties of films were investigated using XRD, AFM, TG-DSC, FTIR, Raman, XPS, SEM and Hall effect measurement, cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry response, UV-vis transmission and absorption spectroscopy, respectively. Especially, we have main studied the effect of the TiO2 incorporation and heat treatment on the micro-structures, morphologies, stoichiometries, electrical properties, ionic intercalation and optical properties of the composite films.We have experimentally determined the optimum parameters of hydrothermal reactions, molar ratio and heat treatment conditions. And obtained high performance ion storage electrode films. The results showed that:V2O5-TiO2 composite thin films were amorphous and with a layered V2O5 matrix structure. TiO2 was dispersed in the host material in the form of amorpohous. TiO2 incorporation led to the reduced interlayer distance and the reduced structure orientation along the c-axis. The grain size and surface roughness of the composite films were remarkablely reduced. Meanwhile TiO2 incorporation also introduced some degree of non-stoichiometry in V2O5, increased the number of oxygen vacancies. Compared with the pure V2O5 gel film, V2O5-TiO2 composite films have a ralatively higher ionic storage capacity and stability, widening and improving the transmission range and intensity of visible light. The cathode coloring response of V2O5-TiO2 composite films was significantly reduced and the transmittance change decreased to 3%. Meanwhile, the V2O5-TiO2 composite films received considerablly high visible light permeability on both ion intercalation and deintercalation status. Through the control of parameters of post-heat treatment, the corresponding changes of crystal structures, surface morphologies and grain structures, oxygen vacancy defects and the energy band structures of the V2O5-TiO2 composite films were generated. On the other hand, Heat treatment optimized the electrical, electrochemical and optical properties of films. The as prepared V2O5-(TiO2)0.2 with the best performance, which can be used as the ion storage layer in electrochromic "smart windows".