Vanadium pentoxide sol solution as well as preparation method and application thereof

Abstract

The invention provides a vanadium pentoxide sol solution as well as a preparation method and application thereof. The preparation method of the vanadium pentoxide sol solution comprises the following steps: adding vanadium pentoxide powder into deionized water for dispersion treatment to prepare the vanadium pentoxide sol solution; wherein the dispersion treatment adopts a treatment mode of alternately circulating heating stirring and ultrasonic dispersion. According to the method, the uniform and stable vanadium pentoxide sol solution can be obtained through the alternate circulation treatment mode, the preparation process is safer, and the preparation technology is easy and convenient to operate, short in consumed time and beneficial to application and popularization. The invention further provides a vanadium pentoxide flexible electrochromic device, the electrochromic device has a classic sandwich structure and good electrochromic performance, and under the action of external voltage, the vanadium pentoxide flexible electrochromic device can be cyclically converted in three states of yellow, green and orange for multiple times.

Description

Technical Field

[0001] The invention belongs to the field of electrochromic material preparation, and specifically comprises a vanadium pentoxide sol solution and a preparation method and application thereof. Background Art

[0002] With the development of emerging technologies such as flexible wearable devices and electronic skin, flexible electrochromic films have become a research hotspot in the field of electrochromic due to their foldability and wearability (Li, W.; Cui, Y., A self-healing polyacrylic acid-based hydrogel electrolyte for flexible quasi-solid-state electrochromic device. Solar Energy Mater. Solar Cells 2023, 250, 112071). Among the flexible substrates, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS) and cellulose paper are several common substrate materials. These flexible substrates have the advantages of small thickness, good flexibility and easy portability, providing a new type of substrate material for the preparation of flexible electrochromic devices.

[0003] Flexible electrochromic devices have the characteristics of light weight and not easy to break. The flexible substrate used is generally an organic material, which makes the weight of the flexible substrate of the same area much smaller than that of the traditional conductive glass substrate, and overcomes the shortcomings of glass fragility and low strength. It can be applied to objects with large curvature on the surface, which will broaden the application areas of electrochromic films. For example, on smart wearable devices, flexible films can better adapt to the curvature of the human body surface and can be mounted on complex curved surfaces, which can better meet actual needs.

[0004] Vanadium pentoxide (V2O5), also known as "vanadic anhydride", is an odorless, orange to dark red amphoteric oxide with a melting point of 680°C. It is insoluble in ethanol, slightly soluble in water, and soluble in strong acids and alkalis. V2O5 has a layered structure and electrochromic properties. When lithium ions are injected into the interlayer space or extracted from the interlayer space, V2O5 will achieve conversion between different valence states (+2, +3, +4, +5). According to the change of applied voltage, V2O5 material will undergo redox reaction, realize the mixing of vanadium ions with different valence states, and present reversible transformation between yellow, green, blue and intermediate colors (Hu, P.; Hu, P.; Vu, T.D.; Li, M.; Wang, S.; Ke, Y.; Zeng, X.; Mai, L.; Long, Y., Vanadium Oxide: Phase Diagrams, Structures, Synthesis, and Applications. Chem. Rev. 2023, 123 (8), 4353-4415). Since V2O5 material has excellent electrochromic properties, researchers have prepared vanadium pentoxide electrochromic thin films using a variety of methods such as spray pyrolysis, hydrothermal method, magnetron sputtering method, electrochemical deposition method, sol-gel method, etc. Among these preparation methods, some require expensive equipment as support, some require special chemical agents such as strong acids and bases or catalysts, and some can only be prepared on rigid substrates such as glass. The electrophoresis method has the advantages of controllable preparation process parameters (such as time and voltage) and simple preparation. It can deposit charged particles evenly on various substrates, especially on flexible substrates to obtain flexible films. However, the vanadium pentoxide sol required for the preparation of vanadium pentoxide films is relatively dangerous during preparation. The vanadium pentoxide needs to be heated to a molten state (about 800°C) and then directly added to deionized water. The thermal effect caused by the large temperature difference may cause harm to the technicians, and it takes a long time (one week). If the vanadium pentoxide sol is prepared by simply stirring at room temperature, it will take even longer, which seriously limits the promotion and application of vanadium pentoxide films.

[0005] Therefore, it is necessary to develop a safer, simpler and faster method to prepare vanadium pentoxide devices with electrochromic properties. Summary of the invention

[0006] In view of the above problems existing in the prior art, the first object of the present invention is to provide a method for preparing a vanadium pentoxide sol solution. The preparation method is completed at low temperature, which is safer than a high-temperature melting method, and the preparation process is simple to operate and takes a short time, which is conducive to the promotion and application of the preparation process.

[0007] The second object of the present invention is to provide a vanadium pentoxide sol solution prepared by the above-mentioned preparation method. The prepared vanadium pentoxide sol solution is uniform and stable, and the color of the sol solution is orange-red, indicating that a large number of vanadium pentoxide particles are dispersed in the sol solution.

[0008] The third object of the present invention is to provide a vanadium pentoxide film.

[0009] The fourth object of the present invention is to provide a method for preparing a vanadium pentoxide flexible electrochromic device.

[0010] The fifth object of the present invention is to provide a vanadium pentoxide flexible electrochromic device prepared by the preparation method as described above. The vanadium pentoxide flexible electrochromic device has a classic "sandwich" structure and good electrochromic performance, and can be repeatedly switched between yellow, green and orange states under the action of an applied voltage.

[0011] To achieve the above first object, the technical solution adopted by the present invention includes:

[0012] The invention discloses a method for preparing a vanadium pentoxide sol solution, comprising the following steps:

[0013] The vanadium pentoxide powder is added into deionized water for dispersion treatment to prepare a vanadium pentoxide sol solution;

[0014] The dispersion treatment adopts a treatment method of alternating cycles of heating and stirring and ultrasonic dispersion.

[0015] In order to solve the problem of high risk and long time consumption in the preparation of vanadium pentoxide sol in the prior art, based on conventional dispersion means, the inventor accidentally discovered that a uniform vanadium pentoxide sol can be obtained quickly by using a treatment method of alternating cycles of heating and stirring and ultrasonic dispersion, and the preparation process is relatively safe. Then, the vanadium pentoxide sol prepared by the present invention can be used to prepare a vanadium pentoxide film with color-changing properties and a vanadium pentoxide flexible electrochromic device, which can achieve multiple cyclic conversions in three states of yellow, green and orange, and is therefore expected to be widely used in emerging technologies such as flexible wearable devices and electronic skin.

[0016] Furthermore, the vanadium pentoxide powder used in the present invention is a commercially available high-purity vanadium pentoxide powder with a purity of 99.99%. The purpose of using the high-purity vanadium pentoxide powder as a raw material is to prepare a vanadium pentoxide film with good color change performance in the later stage and reduce the adverse applications caused by impurities. In the preparation method, the mass of the vanadium pentoxide powder is 2-3g.

[0017] Furthermore, the volume of the deionized water is 100-300 mL, and the resistivity of the deionized water is 18.2 MΩ·cm.

[0018] Furthermore, one heating and stirring and one ultrasonic dispersion are recorded as one cycle, and a total of 3-5 cycles are required for the dispersion treatment to obtain a qualified vanadium pentoxide sol solution.

[0019] Furthermore, the heating and stirring temperature is 50-60° C., and the stirring time is 0.5-1.5 h; the ultrasonic dispersion power is 100-200 W, and the ultrasonic dispersion time is 0.5-1.5 h.

[0020] Furthermore, the dispersion treatment further includes a step of standing at room temperature, which generally takes 2-3 days to ensure that all vanadium pentoxide powder that has not been dispersed into the sol solution is completely settled.

[0021] To achieve the above second purpose, the technical solution adopted by the present invention includes:

[0022] The invention discloses a vanadium pentoxide sol liquid, and the vanadium pentoxide sol liquid is prepared by adopting the preparation method as mentioned above.

[0023] To achieve the third objective, the technical solution adopted by the present invention includes:

[0024] The invention discloses a vanadium pentoxide film. The vanadium pentoxide film is obtained by using the above-mentioned vanadium pentoxide sol solution as a raw material and adopting an electrophoresis method.

[0025] Furthermore, the vanadium pentoxide film is assembled by interweaving nanowires, and the diameter of the nanowires is 10-30nm.

[0026] Furthermore, by adjusting the applied voltage and the electrophoresis time, vanadium pentoxide films of different thicknesses can be obtained. In a specific embodiment, the applied voltage is 3-5V and the electrophoresis time is 0.5-7min.

[0027] To achieve the fourth objective, the technical solution adopted by the present invention includes:

[0028] The present invention discloses a method for preparing a vanadium pentoxide flexible electrochromic device, comprising the following steps:

[0029] The vanadium pentoxide sol solution as described above is used as the electrophoresis solution, a conductive anode and a flexible conductive film are added, and an external voltage is applied for electrophoresis to obtain a vanadium pentoxide-flexible conductive composite film; the vanadium pentoxide-flexible conductive composite film is assembled with another flexible conductive film to obtain a vanadium pentoxide flexible electrochromic device.

[0030] In the traditional process, when preparing vanadium pentoxide color-changing devices, a heat treatment process of 300-500°C is usually carried out. For rigid glass substrates, there is no problem, but since flexible substrates usually have poor heat resistance and cannot withstand high temperature heat treatment processes, based on this, the present invention has developed a preparation method for a vanadium pentoxide flexible electrochromic device. The preparation method has mild conditions and does not require a heat treatment process. It is suitable for preparing electrochromic devices on flexible substrates.

[0031] Furthermore, by adjusting the applied voltage and the electrophoresis time, vanadium pentoxide films of different thicknesses can be obtained. In a specific embodiment, the applied voltage is 3-5V and the electrophoresis time is 0.5-7min.

[0032] Furthermore, the vanadium pentoxide film is assembled by interweaving nanowires, and the diameter of the nanowires is 10-30nm.

[0033] Furthermore, the material of the conductive anode includes but is not limited to FTO conductive glass, ITO conductive glass or platinum sheet, etc.; the flexible conductive film serves as a cathode, and its material includes but is not limited to ITO-PET film, ITO-PEN film or ITO-PI film, etc.; the distance between the conductive anode and the flexible conductive film is 1.5-2cm.

[0034] Furthermore, the FTO conductive glass is fluorine-doped tin dioxide conductive glass, the ITO conductive glass is indium tin oxide conductive glass, the ITO-PET film is indium tin oxide polyethylene terephthalate conductive film, the ITO-PEN film is indium tin oxide polyethylene naphthalate conductive film, and the ITO-PI film is indium tin oxide polyimide conductive film.

[0035] To achieve the fifth objective, the technical solution adopted by the present invention includes:

[0036] The invention discloses a vanadium pentoxide flexible electrochromic device, and the vanadium pentoxide flexible electrochromic device is prepared by adopting the preparation method as described above.

[0037] Beneficial effects of the present invention:

[0038] In the present invention, a uniform and stable vanadium pentoxide sol solution can be obtained by using this alternating cycle treatment method, and the preparation process is safer, and the preparation process is simple to operate and takes a short time, which is conducive to the promotion and application of the preparation process. The present invention also provides a vanadium pentoxide flexible electrochromic device, which has a classic "sandwich" structure and good electrochromic performance. Under the action of an applied voltage, the color of the device can change from the initial yellow to green and orange. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0040] Figure 1 A digital photo of the vanadium pentoxide sol solution prepared in Example 1 is shown.

[0041] Figure 2 A digital photograph of the vanadium pentoxide dispersion prepared in Comparative Example 3 is shown;

[0042] Figure 3 Digital photos of vanadium pentoxide thin films prepared in Comparative Example 1, Comparative Example 2, Example 1, and Example 4 are shown; wherein a shows a digital photo of the thin film prepared in Comparative Example 1; b shows a digital photo of the thin film prepared in Comparative Example 2; c shows a digital photo of the vanadium pentoxide thin film prepared in Example 1; d shows a digital photo of the vanadium pentoxide thin film prepared in Example 4;

[0043] Figure 4 Digital photos of vanadium pentoxide films prepared in Example 2, Example 3, Example 5, and Example 8 are shown; wherein a shows a digital photo of the film prepared in Example 3; b shows a digital photo of the film prepared in Example 2; c shows a digital photo of the film prepared in Example 5; d shows a digital photo of the film prepared in Example 8;

[0044] Figure 5 Digital photos of vanadium pentoxide films prepared in Comparative Examples 3 and 4 are shown; wherein a shows a digital photo of the film prepared in Comparative Example 3; b shows a digital photo of the film prepared in Comparative Example 4;

[0045] Figure 6 The scanning electron microscope photograph of the vanadium pentoxide film prepared in Example 2 is shown;

[0046] Figure 7 The energy spectrum of the vanadium pentoxide film prepared in Example 2 is shown;

[0047] Figure 8 Digital photos of the vanadium pentoxide flexible electrochromic device prepared in Example 2 in different states are shown; a is a flat digital photo, and b is a digital photo in a bent state;

[0048] Fig. 9 A digital photo showing the electrochromic process of preparing a vanadium pentoxide flexible electrochromic device in Example 2;

[0049] Fig.10 The transmission spectra of the vanadium pentoxide flexible electrochromic device prepared in Example 2 in different coloring states are shown: a is the initial yellow state, b is the green coloring state, and c is the orange coloring state.

[0050] Fig.11The color gamut diagram of the vanadium pentoxide flexible electrochromic device prepared in Example 2 during the color change process is shown: a is the initial yellow state, b is the green colored state, and c is the orange colored state. DETAILED DESCRIPTION

[0051] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and drawings. It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] In addition, unless otherwise specified, the raw materials used in the present invention can be obtained commercially, and any range recorded in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0053] Example 1

[0054] Take 2g of vanadium pentoxide powder and disperse it in 200mL of deionized water at room temperature, and then perform the dispersion treatment according to the following cycle, and perform the cycle operation for a total of 5 times, wherein the dispersion liquid is stirred at 50℃ for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion liquid is allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution. Figure 1 As shown, the sol has an obvious "Tyndall effect".

[0055] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode and ITO-PET film as the cathode, and the distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 30s to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film ( Figure 3 As shown in Figure c). The vanadium pentoxide PET film is assembled with another ITO-PET film to prepare a classic "sandwich" structure, and a flexible vanadium pentoxide electrochromic device is obtained. Under the action of an applied voltage, the color of the device can change from the initial yellow to green and orange. When a negative voltage is applied, the color of the device can change from the initial yellow to green, and then a positive voltage is applied, the color of the device can be restored from green to yellow, and the positive voltage is continued to be applied, the color of the device can change to orange, and then a negative voltage is applied again, and the device can be restored from orange to the initial yellow. Therefore, the electrochromic process can be repeated.

[0056] Example 2

[0057] At room temperature, 2 g of vanadium pentoxide powder was dispersed in 100 mL of deionized water, and then the dispersion treatment was carried out according to the following cycle. A total of 5 cycles were performed, wherein the dispersion was stirred at 60°C for 1 h and ultrasonicated at 100 W for 1 h, which was recorded as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0058] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 3min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film.

[0059] Related tests:

[0060] The dried vanadium pentoxide film was subjected to scanning electron microscopy and energy spectrum testing. The scanning electron microscopy photos are shown in Figure 6 As shown in the figure, the surface of the film is mainly composed of interwoven nanowires and the arrangement is relatively regular and tight. The diameter of the nanowires is between 10-30nm. Figure 7 As shown, it can be seen that the film is mainly composed of V and O elements, among which the In element comes from the ITO-PET substrate, and the Au element is treated with gold spraying in order to increase the conductivity of the film during the SEM test.

[0061] Image of the vanadium pentoxide film prepared in this example ( Figure 4 b) shows that the vanadium pentoxide film is a uniform yellow film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure, such as Figure 8 As shown in a, the device is yellow and can be bent ( Figure 8 b), the Lab values ​​of the device were measured by 3nh spectrophotometer (model: YS3010) and were (65.8, -3.75, 41.37). Under the applied voltage, Fig. 9As shown, by applying a negative voltage, the color of the device can change from the initial yellow to green. At this time, the Lab values ​​of the device measured by the spectrophotometer are (54.99, -11.69, 17.1), and then applying a positive voltage, the color of the device can be restored from green to yellow. By continuing to apply a positive voltage, the color of the device can be changed to orange. At this time, the Lab values ​​of the device measured by the spectrophotometer are (59.96, 19.2, 40.46), and by applying a negative voltage again, the device can be restored from orange to the initial yellow. The electrochromic process can be repeated. At the same time, Fig.10 As shown in the figure, the transmission spectrum test shows that the transmittance of the device in different color states is quite different. In the green state, the overall transmittance of the device is low, while in the orange state, the overall transmittance is high. Fig.11 The color gamut diagram of the vanadium pentoxide flexible electrochromic device during the color changing process is shown. In the figure, process 1 shows that the device gradually changes from an initial yellow state to a green state, and process 2 shows that the device gradually recovers from green to yellow and then continues to change to orange.

[0062] Example 3

[0063] At room temperature, 3 g of vanadium pentoxide powder was dispersed in 300 mL of deionized water, and then dispersed according to the following cycle for a total of 3 cycles, wherein the dispersion was stirred at 50°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0064] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 1min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24 hours to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film to prepare a classic "sandwich" structure to obtain a flexible vanadium pentoxide electrochromic device. Under the action of an applied voltage, the color of the device can be repeatedly switched between yellow, green and orange states.

[0065] Image of the vanadium pentoxide film prepared in this example ( Figure 4 As shown in a), the film is a uniform yellow film, and the relevant tests described in the above embodiment 2 are performed, and the test results are basically consistent with those of the above embodiment 2.

[0066] Example 4

[0067] At room temperature, 3 g of vanadium pentoxide powder was dispersed in 200 mL of deionized water, and then dispersed according to the following cycle for a total of 3 cycles, wherein the dispersion was stirred at 60°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0068] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 5V, and adjust the electrophoresis time to 30s to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24 hours to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly converted between three states: yellow, green and orange.

[0069] Image of the vanadium pentoxide film prepared in this example ( Figure 3 d) shows that the film is a uniform yellow film, and the relevant tests described in the above embodiment 2 are carried out, and the test results are basically consistent with those of the above embodiment 2.

[0070] Example 5

[0071] At room temperature, 2 g of vanadium pentoxide powder was dispersed in 100 mL of deionized water, and then the dispersion treatment was carried out according to the following cycle, for a total of 3 cycles, wherein the dispersion was stirred at 50°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0072] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 4 minutes to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24 hours to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film to prepare a classic "sandwich" structure to obtain a flexible vanadium pentoxide electrochromic device. Under the action of an applied voltage, the color of the device can be repeatedly switched between yellow, green and orange states.

[0073] Image of the vanadium pentoxide film prepared in this example ( Figure 4 In c), the film is a yellow film, and the relevant tests described in the above embodiment 2 are performed, and the test results are basically consistent with those of the above embodiment 2.

[0074] Example 6

[0075] Take 2g of vanadium pentoxide powder at room temperature and disperse it in 100mL of deionized water, and then perform dispersion treatment according to the following cycle, for a total of 3 cycles, wherein the dispersion is stirred at 60°C for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion is allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution, which has an obvious "Tyndall effect".

[0076] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 5min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film to prepare a classic "sandwich" structure to obtain a flexible vanadium pentoxide electrochromic device. Under the action of an applied voltage, the color of the device can be repeatedly converted between three states: yellow, green and orange.

[0077] The vanadium pentoxide film prepared in this example is a yellow film, and the relevant tests described in the above embodiment 2 are performed, and the test results are basically consistent with those in the above embodiment 2.

[0078] Example 7

[0079] At room temperature, 3 g of vanadium pentoxide powder was dispersed in 300 mL of deionized water, and then dispersed according to the following cycle for a total of 5 cycles, wherein the dispersion was stirred at 50°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0080] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 6 minutes to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24 hours to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is prepared using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly converted between three states: yellow, green and orange.

[0081] The vanadium pentoxide film prepared in this example is a yellow film, and the relevant tests described in the above embodiment 2 are performed, and the test results are basically consistent with those in the above embodiment 2.

[0082] Example 8

[0083] At room temperature, 2 g of vanadium pentoxide powder was dispersed in 100 mL of deionized water, and then the dispersion treatment was carried out according to the following cycle, for a total of 3 cycles, wherein the dispersion was stirred at 60°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0084] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 3V, and adjust the electrophoresis time to 7min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly switched between yellow, green and orange states.

[0085] Image of the vanadium pentoxide film prepared in this example ( Figure 4 d) shows that the film is a brown-yellow film, and the relevant tests described in the above embodiment 2 are performed, and the test results are basically consistent with the above embodiment 2.

[0086] Example 9

[0087] At room temperature, 2 g of vanadium pentoxide powder was dispersed in 100 mL of deionized water, and then the dispersion treatment was carried out according to the following cycle. A total of 4 cycles were performed, wherein the dispersion was stirred at 50°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0088] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 4V, and adjust the electrophoresis time to 1min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24 hours to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly switched between three states: yellow, green and orange.

[0089] The vanadium pentoxide film prepared in this example is a uniform yellow film, and is subjected to relevant tests as described in the above embodiment 2. The test results are substantially consistent with those in the above embodiment 2.

[0090] Example 10

[0091] Take 2g of vanadium pentoxide powder at room temperature and disperse it in 100mL of deionized water, and then perform dispersion treatment according to the following cycle, and perform a total of 5 cycles, wherein the dispersion is stirred at 50°C for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion is allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which has an obvious "Tyndall effect".

[0092] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 4V, and adjust the electrophoresis time to 3min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly switched between three states: yellow, green and orange.

[0093] The vanadium pentoxide film prepared in this example is a uniform yellow film, and is subjected to relevant tests as described in the above embodiment 2. The test results are substantially consistent with those in the above embodiment 2.

[0094] Embodiment 11

[0095] At room temperature, 3 g of vanadium pentoxide powder was dispersed in 300 mL of deionized water, and then dispersed according to the following cycle for a total of 3 cycles, wherein the dispersion was stirred at 60°C for 1 h and ultrasonicated at 100 W for 1 h as one cycle. After the dispersion treatment, the dispersion was allowed to stand at room temperature for 2 days to obtain an orange-red vanadium pentoxide sol solution, which had an obvious "Tyndall effect".

[0096] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 4V, and adjust the electrophoresis time to 4min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly switched between yellow, green and orange states.

[0097] The vanadium pentoxide film prepared in this example is a yellow film, slightly uneven, and is subjected to relevant tests as described in the above embodiment 2. The test results are basically consistent with those in the above embodiment 2.

[0098] Example 12

[0099] Take 3g of vanadium pentoxide powder at room temperature and disperse it in 300mL of deionized water, and then perform dispersion treatment according to the following cycle, for a total of 3 cycles, wherein the dispersion is stirred at 60°C for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion is allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which has an obvious "Tyndall effect".

[0100] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode, ITO-PET film as the cathode, and the two electrodes are 1.5 cm apart. Use Keithley2400 digital source meter to provide an applied voltage of 5V, and adjust the electrophoresis time to 3min to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film and dry it at room temperature for 24h to prepare the vanadium pentoxide film. The vanadium pentoxide PET film is assembled with another ITO-PET film, and a flexible vanadium pentoxide electrochromic device is obtained using the classic "sandwich" structure. Under the action of an applied voltage, the color of the device can be repeatedly switched between three states: yellow, green and orange.

[0101] The vanadium pentoxide film prepared in this example is a uniform yellow film, and is subjected to relevant tests as described in the above embodiment 2. The test results are substantially consistent with those in the above embodiment 2.

[0102] Comparative Example 1

[0103] Take 2g of vanadium pentoxide powder at room temperature and disperse it in 100mL of deionized water, and then perform dispersion treatment according to the following cycle, for a total of 5 cycles, wherein the dispersion is stirred at 60°C for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion is allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which has an obvious "Tyndall effect".

[0104] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode and ITO-PET film as the cathode, and the distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 2V and adjust the electrophoresis time to 30s to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film, such as Figure 3 As shown in a, vanadium pentoxide cannot be plated on the ITO-PET film at this time, indicating that the external voltage during electrophoresis is an important factor, and if it is too small, the film cannot be successfully plated.

[0105] Comparative Example 2

[0106] Take 2g of vanadium pentoxide powder at room temperature and disperse it in 100mL of deionized water, and then perform dispersion treatment according to the following cycle, for a total of 5 cycles, wherein the dispersion is stirred at 60°C for 1h and ultrasonicated at 100W for 1h as one cycle. After the dispersion treatment, the dispersion is allowed to stand at room temperature for 3 days to obtain an orange-red vanadium pentoxide sol solution, which has an obvious "Tyndall effect".

[0107] Take an appropriate amount of the vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode and ITO-PET film as the cathode, and the distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 2.5V and adjust the electrophoresis time to 30s to prepare the vanadium pentoxide film. After the electrophoresis is completed, take out the film, such as Figure 3 As shown in b, at this time there is only a part of vanadium pentoxide film at the bottom of the ITO-PET film, and the coating cannot be successfully performed even if the voltage is increased to 2.5V.

[0108] Comparative Example 3

[0109] Take 2 g of vanadium pentoxide powder at room temperature and disperse it in 100 mL of deionized water. Treat it in the following way: first, stir the dispersion at 60°C for 5 h, then ultrasonicate it at 100 W for 5 h. After the dispersion treatment, let the dispersion stand at room temperature for 3 days to obtain only a light yellow clear liquid.

[0110] Take an appropriate amount of the light yellow vanadium pentoxide sol solution and transfer it to a beaker. Put FTO conductive glass as the anode and ITO-PET film as the cathode. The distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 3V and adjust the electrophoresis time to 3min to prepare vanadium pentoxide film. After the electrophoresis is completed, take out the film. Figure 5 As shown in a, vanadium pentoxide cannot be plated on the ITO-PET film at this time, indicating that the light yellow vanadium pentoxide sol solution cannot be used to prepare a vanadium pentoxide film.

[0111] Comparative Example 4

[0112] Take 2 g of vanadium pentoxide powder at room temperature and disperse it in 100 mL of deionized water. Treat it in the following way: first, stir the dispersion at 60°C for 5 h, then ultrasonicate it at 100 W for 5 h. After the dispersion treatment, let the dispersion stand at room temperature for 3 days to obtain only a light yellow clear liquid.

[0113] Take an appropriate amount of the light yellow vanadium pentoxide sol solution and transfer it to a beaker, put FTO conductive glass as the anode and ITO-PET film as the cathode, and the distance between the two electrodes is 1.5 cm. Use Keithley2400 digital source meter to provide an applied voltage of 3V and adjust the electrophoresis time to 7min to prepare vanadium pentoxide film. After the electrophoresis is completed, take out the film. Figure 5 As shown in b, even if the electrophoresis time is prolonged, vanadium pentoxide cannot be plated on the ITO-PET film, indicating that the light yellow vanadium pentoxide sol solution cannot be used to prepare a vanadium pentoxide film.

[0114] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a vanadium pentoxide sol solution, characterized in that: The steps include: The vanadium pentoxide powder is added into deionized water for dispersion treatment to prepare a vanadium pentoxide sol solution; The dispersion treatment adopts a treatment method of alternating cycles of heating and stirring and ultrasonic dispersion.

2. The preparation method according to claim 1, characterized in that: The mass of the vanadium pentoxide powder is 2-3 g, and the purity is 99.99%.

3. The preparation method according to claim 1, characterized in that: The volume of the deionized water is 100-300 mL.

4. The preparation method according to claim 1, characterized in that: The heating, stirring and ultrasonic dispersion alternating cycle treatment is carried out for 3-5 cycles in total.

5. The preparation method according to claim 1, characterized in that: The heating and stirring temperature is 50-60°C, and the stirring time is 0.5-1.5h; The power of the ultrasonic dispersion is 100-200W, and the ultrasonic dispersion time is 0.5-1.5h.

6. A vanadium pentoxide sol solution, characterized in that: The preparation method is described in any one of claims 1 to 5.

7. A vanadium pentoxide film, characterized in that: The vanadium pentoxide sol solution according to claim 6 is used as a raw material, and a vanadium pentoxide film is obtained by electrophoresis.

8. A method for preparing a vanadium pentoxide flexible electrochromic device, characterized in that: The steps include: The vanadium pentoxide sol solution described in claim 6 is used as an electrophoresis liquid, a conductive anode and a flexible conductive film are added, and an external voltage is applied for electrophoresis to obtain a vanadium pentoxide-flexible conductive composite film; the vanadium pentoxide-flexible conductive composite film is assembled with another flexible conductive film to obtain a vanadium pentoxide flexible electrochromic device.

9. The preparation method according to claim 8, characterized in that: The applied voltage is 3-5V, and the electrophoresis time is 0.5-7min.

10. A vanadium pentoxide flexible electrochromic device, characterized in that: The preparation is obtained by the preparation method as claimed in claim 8 or 9.

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