## Results
### Electrochromic Properties of the Grown WO\({}_{3}\) Film  
WO\({}_{3}\) electrochromism is explained by reversible reduction and oxidation reactions accompanied by the intercalation/deinterclation of lithium ions, which can be expressed by the following equation:  
\[\text{WO}_{3}(\text{colorless})+\text{x}\big{(}\text{Li}^{+}+\text{e}^{-}\big{)} =\text{Li}_{\text{x}}\text{W}_{(1-\text{x})}^{+\text{VI}}\text{W}_{\text{x}}^{+ \text{V}}\text{O}_{3}(\text{dark blue}) \tag{2}\]  
Accordingly, to study the electrochromic properties of WO\({}_{3}\), it is necessary to monitor both the changes in the optical parameters of the film and the electrochemical processes taking place. Therefore, first of all, to characterize the electrochromic properties of the WO\({}_{3}\) film grown on the glass/ITO substrate surface, cyclic voltammetry (CV) was recorded in parallel with monitoring changes in the sample transmittance at \(\lambda\) = 600 nm during this experiment (Figure 8a,b). During the first two cycles of recording, the film and its electrochemical behavior were stabilizing; Figure 8 shows CV and data on the change in transmission during its recording for the stabilized sample. Several effects can be distinguished. First, a broad and intense peak during oxidation of the material starting at about 0.2 V, peaking at 1.31 V (I = 1.24 mA), and ending at about 2 V. This effect clearly refers to the oxidation of the material with the deinterclation of lithium ions and bleaching of the cell--Figure 8b shows that at around 0.2 V, the bleaching begins, and the curve of change in transmittance begins to reach a plateau at around 1.6 V, when the intensity of the electrochemical process had already passed through the maximum and began to decrease noticeably. It is interesting that the coloration after the stabilization of the sample seems to possess a two-step character: at first, upon the decrease in potential from 2.2 V to \(\sim\)0.9 V, the film is still slightly bleached; upon reaching \(\sim\)0.9 V, it begins to color gradually, and then, upon reaching \(-\)2.5 V, the rate of the coloration process sharply increases. Indeed, some increase in the current started at around 0.9 V on the cathode branch, reached its maximum at 0.295 V (I\({}_{\text{max}}\) = \(-\)0.023 mA), and gradually subsided. We could not distinguish any separate peak at \(-\)2.5 V--the process is obviously low-intensive in terms of current. The presence of two stages can probably be explained by the formation of two phases after the stabilization of the material--one begins to oxidize earlier but makes a smaller contribution to coloration, and the second begins to oxidize later and makes a larger contribution to coloration. The second phase most likely intercalates fewer lithium ions than the first, which is why it has a lower current intensity on CV. It could then be assumed that the first phase is closer in its crystal structure to the intermediate phase between WO\({}_{3}\) and LiWO\({}_{3}\) formed during lithium intercalation upon reduction--the formed intermediate phase is apparently not completely oxidized back to WO\({}_{3}\), so the structure is preserved and ready for the intensive intercalation of lithium ions upon earlier reduction. During CV recording, the maximum optical contrast at 600 nm reaches 7.5%, but it can be seen from Figure 8c that when a constant potential is applied, a much greater effect is achieved--the contrast is approximately 17.5% and remains at this level (Figure 8c). From the transmittance spectra of the film in the different states (Figure 8d), it can be seen that the sample does not return to its original state as a result of cycling, darkening by an average of 5%, and the contrast between the colored and bleached states in the 550-1100 nm range varies between 11 and 18%, increasing with wavelength.