A preparation method and application of an electrochromic device based on niobium-tungsten bimetal oxide material
FTO/niobium-tungsten bimetallic oxide thin films and counter electrode layers were prepared by magnetron sputtering and electrochemical deposition. Combined with an electrolyte solution of composite conductive material, the complexity and inhomogeneity of niobium-tungsten bimetallic oxide electrochromic thin films were solved, and efficient and uniform electrochromic effects were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGBEI UNIV
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-19
AI Technical Summary
The existing niobium-tungsten bimetallic oxide electrochromic thin film preparation process is complex, has poor repeatability, and the color change response is not fast enough or uniform enough.
FTO/niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering, and counter electrode thin film layers were prepared by magnetron sputtering or electrochemical deposition. An electrolyte solution containing composite conductive materials was prepared, and a sandwich structure was formed by using double-sided adhesive and then injected with the electrolyte solution. The preparation process is simple and easy to mass-produce.
The prepared electrochromic device film has a nanosheet or nanoflower structure on its surface, exhibiting good electrochromic effect, high cycle stability, fast response speed, uniform color change, low environmental pollution, and low cost.
Smart Images
Figure CN122239331A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochromic device fabrication technology, specifically a method for fabricating and applying an electrochromic device based on niobium-tungsten bimetallic oxide material. Background Technology
[0002] Electrochromism refers to the phenomenon where the optical properties of a material or device undergo stable and reversible color changes under the influence of an applied electric field, manifesting as reversible changes in color and transparency. A typical electrochromic device mainly consists of a multi-layer structure comprising a bottom conductive electrode / ion storage layer / ion electrolyte layer / electrochromic layer / top conductive electrode. When an external voltage is applied across the electrode terminals, ions and free electrons continuously move within and outside the device, causing changes in its color or spectral characteristics. The electrochromic material is the core of the electrochromic device; the co-implantation / extraction (redox reaction) process of ions and electrons in the color-changing layer directly determines the overall spectral modulation performance of the device. Simultaneously, with the continuous emergence of various non-lithium ion (such as ammonium ion, zinc ion, calcium ion, aluminum ion, etc.) based electrochromic devices, the development of electrochromic materials that meet the different ion insertion / extraction requirements is becoming increasingly urgent.
[0003] Currently, commonly used electrochromic materials can be divided into two main categories: inorganic and organic electrochromic materials. Among them, inorganic metal oxides (WO3) have been widely used in various types of electrochromic devices due to their advantages such as good cycle stability, wide optical modulation amplitude, strong adhesion, and good thermal stability. In recent years, niobium-tungsten bimetallic oxides have attracted widespread attention due to their good electronic conductivity and multiple channel structures that facilitate ion transport. For example, Cai et al. (Advanced Energy Materials, 2021, 12(5): 2103106) prepared niobium-tungsten bimetallic oxide electrochromic films using an electrospray aerosol deposition pyrolysis method and showed good spectral modulation performance in zinc ion-based electrolytes. Liu et al. (ACS Nano, 2022, 16(2): 2621-2628) prepared niobium-tungsten bimetallic oxide electrochromic films using a spin coating method and showed good electrochromic performance in lithium ion-based electrolytes. However, the above-mentioned methods for preparing niobium-tungsten bimetallic oxide electrochromic thin films are complex and have poor repeatability, which is not conducive to their widespread application. Furthermore, existing electrochromic devices suffer from insufficient color-changing response speed and uneven color change. Therefore, we propose a method for preparing and applying electrochromic devices based on niobium-tungsten bimetallic oxide materials. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing and applying an electrochromic device based on niobium-tungsten bimetallic oxide material, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material, characterized in that the fabrication method includes the following steps: S1. FTO / niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering. S2. Prepare a counter electrode thin film layer on FTO or ITO transparent conductive glass by magnetron sputtering or electrochemical deposition. S3. Prepare the electrolyte solution; S4. Apply double-sided tape around the upper surface of the FTO / niobium-tungsten bimetallic oxide film, and then attach the upper surface of the counter electrode film layer to the double-sided tape to obtain a sandwich structure. S5. Inject the electrolyte solution into the pores of the sandwich structure, and seal the edges with quick-drying adhesive to obtain the electrochromic device. The electrolyte solution in step S3 includes a composite conductive material, an electrolyte, and deionized water. The preparation method of the composite conductive material includes the following steps: S101. Grind carbon fiber together with sodium hydroxide. Then, heat the ground product at 500-600℃ for 20-40 minutes under a nitrogen atmosphere, and then raise the temperature to 700-800℃ and continue heating for 20-40 minutes. S102. Wash the carbon fiber treated in step S101 with water. After washing, add the carbon fiber to concentrated nitric acid and heat to 60-90℃ for 4-8 hours. Then filter. After further washing, dry the filtered product at 60-90℃ for 2-4 hours. S103. Disperse carbon nanotubes ultrasonically in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, heat to 60-90℃ for 1-2 hours, then filter, and wash the filtered product with water. S104. The carbon nanotubes treated in step S103 are ultrasonically dispersed in an ethanol solution of 3-aminopropyltriethoxysilane and heated to 50-80℃ for 2-4 hours. After that, the mixture is filtered, the filtered product is washed with water and then dried at 60-90℃ for 2-4 hours. S105. The carbon fibers treated in step S102 and the carbon nanotubes treated in step S104 are ultrasonically dispersed in acetone. Then, sodium hydroxide solution is added dropwise to adjust the pH to 8-9. The reaction is carried out for 1-3 hours. After filtration, the filtered product is washed with water and dried at 60-90℃ for 2-4 hours to obtain the composite conductive material. The electrolyte is one of the following: ammonium salt, zinc salt, calcium salt, and aluminum salt.
[0006] Furthermore, the preparation of FTO / niobium-tungsten bimetallic oxide thin films by magnetron sputtering in step S1 specifically includes the following steps: S201. Place the FTO glass in acetone, alcohol, and deionized water for ultrasonic cleaning for 10 minutes each, and then dry it with a hair dryer for later use. S202. After applying vacuum tape to one side of the cleaned FTO glass front, place it on the sample stage in the vacuum chamber of the magnetron sputtering system. S203. The sputtering target material is pure tungsten metal or tungsten oxide, niobium metal or niobium oxide. The FTO glass is rotated at a constant speed of 5-12º / s for sputtering. During the sputtering process, the FTO glass is heated to 400-500℃. Before the formal sputtering, a pre-sputtering is performed for 3-5 minutes to remove contamination from the target surface. S204. After sputtering is completed and the sample has cooled for 20 minutes, open the vacuum chamber and take out the sample. Remove the vacuum tape from the sample surface and place the sample in a vacuum tube furnace for heat treatment in an argon atmosphere. After heat treatment, take out the sample and place it in a drying oven for storage, thus obtaining an FTO / niobium-tungsten bimetallic oxide film.
[0007] Furthermore, in step S202, the vacuum level of the vacuum chamber is evacuated to 3 × 10⁻⁶. -3 Below Pa, the working gas is a mixture of argon and oxygen, with a flow ratio of argon to oxygen of 1:1 to 5:1, and the working pressure is set between 1.0 and 2.5 Pa; in step S203, the power of the sputtering power supply for the tungsten metal or tungsten oxide target is set between 100 and 200 W, the power of the sputtering power supply for the niobium metal or niobium oxide target is set between 150 and 300 W, and the sputtering time is set between 10 and 60 min.
[0008] Furthermore, in step S101, the mass ratio between carbon fiber and sodium hydroxide is 1:(4-6).
[0009] Furthermore, the concentration of concentrated nitric acid in step S102 and the concentration of concentrated nitric acid in step S103 are both 68 wt%, the concentration of concentrated sulfuric acid in step S103 is 98 wt%, and the volume ratio between concentrated nitric acid and concentrated sulfuric acid in step S103 is 1:2.
[0010] Furthermore, in step S104, the concentration of 3-aminopropyltriethoxysilane in the ethanol solution of 3-aminopropyltriethoxysilane is 3-6 wt%.
[0011] Furthermore, in step S105, the mass ratio between the carbon fiber treated in step S102, the carbon nanotubes treated in step S104, and acetone is 1:(5-10):(80-120).
[0012] Furthermore, the concentration of the electrolyte in the electrolyte solution is 5 mol / L, and the mass ratio between the composite conductive material and deionized water is 1:(10-15).
[0013] Furthermore, in step S2, nickel oxide and lithium manganese oxide films with a thickness of 300-800 nm are deposited on the transparent conductive glass using magnetron sputtering; and vanadium oxide, manganese oxide, polyaniline, or Prussian blue films with a thickness of 100-1000 nm are deposited on the transparent conductive glass using electrochemical deposition.
[0014] The electrochromic devices prepared by the above-mentioned method based on niobium-tungsten bimetallic oxide materials can be applied in the fields of smart building glass, smart display, automotive sunroof and smart thermal control.
[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention can obtain niobium-tungsten bimetallic oxide thin films on FTO conductive glass by adjusting parameters such as sputtering power, argon / oxygen flow ratio, in-situ heating temperature and time. The surface of the niobium-tungsten bimetallic oxide thin film has a nanosheet or nanoflower structure, and the film has a good electrochromic effect. 2. This invention prepares a niobium-tungsten bimetallic oxide thin film, wherein both Nb and W have variable valence states and contain a variety of nanoporous structures, which can overcome the defect of insufficient cycle stability; 3. The preparation process of this invention is simple, highly reproducible, has low environmental pollution, is easy to prepare on a large scale and in large batches, and has low cost; 4. In this invention, a composite conductive material is added to the electrolyte solution. The composite conductive material is composed of carbon fibers and carbon nanotubes. The carbon fibers are heated together with sodium hydroxide, which greatly increases their surface area. Carbon nanotubes are then composited on the surface of the carbon fibers. The introduction of carbon nanotubes allows the carbon fibers to overlap into a more three-dimensional conductive network. Furthermore, the introduced carbon nanotubes introduce a large number of functional groups, which can adsorb a large number of ions in the electrolyte solution and induce rapid ion transport in the electrolyte solution. This shortens the color change time at the edges and center, and improves uniformity. Attached Figure Description
[0016] Figure 1 This is a flowchart of the process flow of the present invention; Figure 2 This is a process flow diagram for preparing the composite conductive material according to the present invention; Figure 3 This is a process flow diagram for preparing FTO / niobium-tungsten bimetallic oxide thin films according to the present invention; Figure 4 The X-ray diffraction pattern of the niobium-tungsten bimetallic oxide thin film in Example 1 of this invention is shown below. Figure 5 This is a scanning electron microscope image of the niobium-tungsten bimetallic oxide thin film in Example 1 of the present invention; Figure 6 This is a flowchart illustrating the fabrication process of the electrochromic device according to the present invention; Figure 7 The visible light transmittance diagram of the electrochromic device prepared in Example 1 of the present invention at different wavelengths; Figure 8 The figure shows the cycle stability test results of the FTO / niobium-tungsten bimetallic oxide film prepared in Example 1 of this invention and WO3. Detailed Implementation
[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Please see Figures 1 to 8 The present invention provides: Example 1 A method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material, the method comprising the following steps: S1. FTO / niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering. The preparation of FTO / niobium-tungsten bimetallic oxide thin films by magnetron sputtering in step S1 specifically includes the following steps: S201. Place the FTO glass in acetone, alcohol, and deionized water for ultrasonic cleaning for 10 minutes each, and then dry it with a hair dryer for later use. S202. After applying vacuum tape to one side of the cleaned FTO glass front, place it on the sample stage in the vacuum chamber of the magnetron sputtering system. The vacuum level in the vacuum chamber was evacuated to 3 × 10⁻⁶. -3 Below Pa, the working gas is a mixture of argon and oxygen, with a flow ratio of argon to oxygen of 2:1, and the working pressure is set at 1.5 Pa. S203. The sputtering target material is pure tungsten metal or tungsten oxide, niobium metal or niobium oxide. The FTO glass is rotated at a constant speed of 8º / s for sputtering. During the sputtering process, the FTO glass is heated to a temperature of 450℃. A 5-minute pre-sputtering is performed before the formal sputtering to remove contaminants from the target surface. The power of the sputtering power supply for the tungsten metal or tungsten oxide target is set to 150W (tungsten metal is selected), the power of the sputtering power supply for the niobium metal or niobium oxide target is set to 180W (niobium metal is selected), the sputtering time is set to 30 min, and the niobium-tungsten alloy target is (Nb:W=1:1, 99.99%). S204. After sputtering is completed and the sample has cooled for 20 minutes, open the vacuum chamber and take out the sample. Remove the vacuum tape from the sample surface and place the sample in a vacuum tube furnace for heat treatment in an argon atmosphere. After heat treatment, take out the sample and place it in a drying oven for storage and to obtain an FTO / niobium-tungsten bimetallic oxide film. S2. Prepare a counter electrode thin film layer on FTO or ITO transparent conductive glass by magnetron sputtering or electrochemical deposition. Nickel oxide (NiO) and lithium manganese oxide (LiMn2O4) films with a thickness of 300-800 nm were deposited on transparent conductive glass by magnetron sputtering; vanadium oxide, manganese oxide, polyaniline, or Prussian blue films with a thickness of 100-1000 nm were deposited on transparent conductive glass by electrochemical deposition. In this embodiment, a nickel oxide thin film with a thickness of 500 nm is deposited on FTO transparent conductive glass using magnetron sputtering. S3. Prepare the electrolyte solution; The electrolyte solution in step S3 includes a composite conductive material, an electrolyte, and deionized water; The preparation method of composite conductive materials includes the following steps: S101. Grind 15g of carbon fiber with 75g of sodium hydroxide together. Then, heat the ground product at 550°C for 30min under a nitrogen atmosphere, and then raise the temperature to 750°C and continue heating for 30min. S102. The carbon fiber treated in step S101 is washed with water. After washing, the carbon fiber is added to 100ml of concentrated nitric acid and heated to 80℃ for 5h. The concentration of concentrated nitric acid is 68wt%. After filtration, the filtered product is washed with water again and then dried at 75℃ for 3h. S103. 5g of carbon nanotubes were ultrasonically dispersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid and heated to 80℃ for 1.5h. The amount of concentrated nitric acid was 20ml and the amount of concentrated sulfuric acid was 40ml. The concentrations of concentrated nitric acid and concentrated sulfuric acid were 68wt% and 98wt%, respectively. After filtration, the filtered product was washed with water. S104. The carbon nanotubes treated in step S103 are ultrasonically dispersed in 40 ml of ethanol solution of 5 wt% 3-aminopropyltriethoxysilane and heated to 70 °C for 3 h. After filtration, the filtered product is washed with water and dried at 80 °C for 3 h. S105. 10g of carbon fiber treated in step S102 and 1.5g of carbon nanotubes treated in step S104 are ultrasonically dispersed in 150g of acetone. Then, sodium hydroxide solution is added dropwise to adjust the pH to 8.5. The reaction is carried out for 2 hours. After filtration, the filtered product is washed with water and dried at 80°C for 3 hours to obtain the composite conductive material. The electrolyte is one of the following: ammonium ion salt (which can be ammonium chloride, ammonium sulfate or ammonium acetate), zinc ion salt (which can be zinc perchlorate, zinc trifluoromethanesulfonate, zinc sulfate or zinc acetate), calcium ion salt (which can be calcium trifluoromethanesulfonate), and aluminum ion salt (which can be aluminum perchlorate or aluminum chloride). In this embodiment, zinc trifluoromethanesulfonate was specifically used. Subsequent embodiments and comparative examples all used the same electrolyte (zinc trifluoromethanesulfonate) as in Example 1. The concentration of the electrolyte in the electrolyte solution is 5 mol / L, and the mass ratio between the composite conductive material and deionized water is 1:12. S4. Apply double-sided tape around the upper surface of the FTO / niobium-tungsten bimetallic oxide film, and then attach the upper surface of the counter electrode film layer to the double-sided tape to obtain a sandwich structure. S5. Inject the electrolyte solution into the pores of the sandwich structure, and seal the edges with quick-drying adhesive to obtain the electrochromic device.
[0019] Example 2 A method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material, the method comprising the following steps: S1. FTO / niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering. The preparation of FTO / niobium-tungsten bimetallic oxide thin films by magnetron sputtering in step S1 specifically includes the following steps: S201. Place the FTO glass in acetone, alcohol, and deionized water for ultrasonic cleaning for 10 minutes each, and then dry it with a hair dryer for later use. S202. After applying vacuum tape to one side of the cleaned FTO glass front, place it on the sample stage in the vacuum chamber of the magnetron sputtering system. In step S202, the vacuum level in the vacuum chamber is evacuated to 3 × 10⁻⁶. -3 Below Pa, the working gas is a mixture of argon and oxygen, with a flow ratio of argon to oxygen of 1:1, and the working pressure is set at 1.0 Pa. S203. The sputtering target material is pure tungsten metal or tungsten oxide, niobium metal or niobium oxide. The FTO glass is rotated at a constant speed of 5º / s for sputtering. During the sputtering process, the FTO glass is heated to 400℃. A 3-minute pre-sputtering is performed before the formal sputtering to remove contaminants from the target surface. In step S203, the power of the sputtering power supply for the tungsten metal or tungsten oxide target is set to 100 W (tungsten metal is selected), the power of the sputtering power supply for the niobium metal or niobium oxide target is set to 300 W (niobium metal is selected), the sputtering time is set to 10 min, and the niobium-tungsten alloy target is (Nb:W=1:1, 99.99%). S204. After sputtering is completed and the sample has cooled for 20 minutes, open the vacuum chamber and take out the sample. Remove the vacuum tape from the sample surface and place the sample in a vacuum tube furnace for heat treatment in an argon atmosphere. After heat treatment, take out the sample and place it in a drying oven for storage and to obtain an FTO / niobium-tungsten bimetallic oxide film. S2. Prepare a counter electrode thin film layer on FTO or ITO transparent conductive glass by magnetron sputtering or electrochemical deposition. Nickel oxide (NiO) and lithium manganese oxide (LiMn2O4) films with a thickness of 300-800 nm were deposited on transparent conductive glass by magnetron sputtering; vanadium oxide, manganese oxide, polyaniline, or Prussian blue films with a thickness of 100-1000 nm were deposited on transparent conductive glass by electrochemical deposition. In this embodiment, a nickel oxide thin film with a thickness of 500 nm is deposited on FTO transparent conductive glass using magnetron sputtering. S3. Prepare the electrolyte solution; The electrolyte solution in step S3 includes a composite conductive material, an electrolyte, and deionized water; The preparation method of composite conductive materials includes the following steps: S101. Grind 15g of carbon fiber with 60g of sodium hydroxide together. Then, heat the ground product at 500°C for 20 minutes under a nitrogen atmosphere, and then raise the temperature to 700°C and continue heating for 20 minutes. S102. The carbon fiber treated in step S101 is washed with water. After washing, the carbon fiber is added to 100ml of concentrated nitric acid and heated to 60℃ for 4h. The concentration of concentrated nitric acid is 68wt%. After filtration, the filtered product is washed with water again and then dried at 60℃ for 2h. S103. 5g of carbon nanotubes were ultrasonically dispersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid and heated to 60°C for 1 hour. The amount of concentrated nitric acid used was 20ml and the amount of concentrated sulfuric acid used was 40ml. The concentrations of concentrated nitric acid and concentrated sulfuric acid were 68wt% and 98wt%, respectively. After filtration, the filtered product was washed with water. S104. The carbon nanotubes treated in step S103 are ultrasonically dispersed in 40 ml of ethanol solution of 3-aminopropyltriethoxysilane with a concentration of 3wt%, heated to 50°C for 2 h, filtered, and the filtered product is washed with water and dried at 60°C for 2 h. S105. 10g of carbon fiber treated in step S102 and 2g of carbon nanotubes treated in step S104 are ultrasonically dispersed in 160g of acetone. Then, sodium hydroxide solution is added dropwise to adjust the pH to 8. The reaction is carried out for 1 hour. After filtration, the filtered product is washed with water and dried at 60°C for 2 hours to obtain the composite conductive material. The concentration of the electrolyte (zinc trifluoromethanesulfonate) in the electrolyte solution is 5 mol / L, and the mass ratio between the composite conductive material and deionized water is 1:10. S4. Apply double-sided tape around the upper surface of the FTO / niobium-tungsten bimetallic oxide film, and then attach the upper surface of the counter electrode film layer to the double-sided tape to obtain a sandwich structure. S5. Inject the electrolyte solution into the pores of the sandwich structure, and seal the edges with quick-drying adhesive to obtain the electrochromic device.
[0020] Example 3 A method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material, the method comprising the following steps: S1. FTO / niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering. The preparation of FTO / niobium-tungsten bimetallic oxide thin films by magnetron sputtering in step S1 specifically includes the following steps: S201. Place the FTO glass in acetone, alcohol, and deionized water for ultrasonic cleaning for 10 minutes each, and then dry it with a hair dryer for later use. S202. After applying vacuum tape to one side of the cleaned FTO glass front, place it on the sample stage in the vacuum chamber of the magnetron sputtering system. In step S202, the vacuum level in the vacuum chamber is evacuated to 3 × 10⁻⁶. -3 Below Pa, the working gas is a mixture of argon and oxygen, with a flow ratio of argon to oxygen of 5:1, and the working pressure is set at 2.5 Pa. S203. The sputtering target material is selected as pure tungsten metal or tungsten oxide (selected as tungsten metal), niobium metal or niobium oxide (selected as niobium metal). The FTO glass is rotated at a constant speed of 12º / s for sputtering. During the sputtering process, the FTO glass is heated to 500℃. A 3-minute pre-sputtering is performed before the formal sputtering to remove contaminants from the target surface. In step S203, the power of the sputtering power supply for the tungsten metal or tungsten oxide target is set to 200 W, the power of the sputtering power supply for the niobium metal or niobium oxide target is set to 300 W, the sputtering time is set to 60 min, and the niobium-tungsten alloy target is (Nb:W=1:1, 99.99%). S204. After sputtering is completed and the sample has cooled for 20 minutes, open the vacuum chamber and take out the sample. Remove the vacuum tape from the sample surface and place the sample in a vacuum tube furnace for heat treatment in an argon atmosphere. After heat treatment, take out the sample and place it in a drying oven for storage, thus obtaining an FTO / niobium-tungsten bimetallic oxide film.
[0021] S2. Prepare a counter electrode thin film layer on FTO or ITO transparent conductive glass by magnetron sputtering or electrochemical deposition. Nickel oxide (NiO) and lithium manganese oxide (LiMn2O4) films with a thickness of 300-800 nm were deposited on transparent conductive glass by magnetron sputtering; vanadium oxide, manganese oxide, polyaniline, or Prussian blue films with a thickness of 100-1000 nm were deposited on transparent conductive glass by electrochemical deposition. In this embodiment, a nickel oxide thin film with a thickness of 500 nm is deposited on FTO transparent conductive glass using magnetron sputtering. S3. Prepare the electrolyte solution; The electrolyte solution in step S3 includes a composite conductive material, an electrolyte, and deionized water; The preparation method of composite conductive materials includes the following steps: S101. Grind 15g of carbon fiber with 75g of sodium hydroxide together. Then, heat the ground product at 600°C for 40min under a nitrogen atmosphere, and then raise the temperature to 800°C and continue heating for 40min. S102. The carbon fiber treated in step S101 is washed with water. After washing, the carbon fiber is added to 100ml of concentrated nitric acid and heated to 90℃ for 8h. The concentration of concentrated nitric acid is 68wt%. After filtration, the filtered product is washed with water again and then dried at 90℃ for 4h. S103. 5g of carbon nanotubes were ultrasonically dispersed in a mixed solution of concentrated nitric acid and concentrated sulfuric acid and heated to 90℃ for 2h. The amount of concentrated nitric acid was 20ml and the amount of concentrated sulfuric acid was 40ml. The concentrations of concentrated nitric acid and concentrated sulfuric acid were 68wt% and 98wt%, respectively. After filtration, the filtered product was washed with water. S104. The carbon nanotubes treated in step S103 are ultrasonically dispersed in 40 ml of ethanol solution of 6 wt% 3-aminopropyltriethoxysilane and heated to 80 °C for 4 h. After filtration, the filtered product is washed with water and dried at 90 °C for 4 h. S105. 10g of carbon fiber treated in step S102 and 1g of carbon nanotubes treated in step S104 are ultrasonically dispersed in 120g of acetone. Then, sodium hydroxide solution is added dropwise to adjust the pH to 9. The reaction is carried out for 3 hours. After filtration, the filtered product is washed with water and dried at 90°C for 4 hours to obtain the composite conductive material. The concentration of the electrolyte (zinc trifluoromethanesulfonate) in the electrolyte solution is 5 mol / L, and the mass ratio between the composite conductive material and deionized water is 1:15. S4. Apply double-sided tape around the upper surface of the FTO / niobium-tungsten bimetallic oxide film, and then attach the upper surface of the counter electrode film layer to the double-sided tape to obtain a sandwich structure. S5. Inject the electrolyte solution into the pores of the sandwich structure, and seal the edges with quick-drying adhesive to obtain the electrochromic device.
[0022] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step S101 is omitted, while the remaining steps are exactly the same as in Example 1.
[0023] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that steps S103-S105 are omitted, while the remaining steps are exactly the same as in Example 1.
[0024] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the addition of the composite conductive material was completely eliminated, while the remaining steps were exactly the same as in Example 1.
[0025] To clearly elucidate the crystallinity, crystal structure, and symmetry of the niobium-tungsten bimetallic oxide thin film, the film was characterized by XRD, Raman, and XPS. Figure 4 XRD characterization results showed sharp diffraction peaks, consistent with orthorhombic FTO / niobium-tungsten bimetallic oxide films (Nb). 18 W 16 O 93 (JCPDS 75-0561) matches well, and no other impurity phases were found. The orthorhombic Nb 18 W 16 O 93 With pentagonal, quadrilateral, and triangular tunnel cavity structures, it can well support the rapid diffusion behavior of cations such as zinc ions, thereby realizing rapid electrochromic response and high-rate energy storage. Figure 5 (ab) is Nb 18 W 16 O 93 The surface morphology image of the electrochromic thin film reveals nanoparticles of different sizes, their clusters, and the nanoscale porous structure, indicating that the Nb2O3 film prepared by spin coating... 18 W 16 O 93The electrochromic film is uniformly adhered to a glass substrate coated with FTO. Furthermore, the porous three-dimensional nanostructure formed by stacked nanoparticles provides abundant active sites for electrolyte ions and a larger effective contact area at the electrolyte-electrode interface, thereby shortening the ion diffusion distance, achieving a higher diffusion coefficient and faster response time, and ultimately promising excellent electrochemical electrochromic performance.
[0026] Figure 7 The visible light transmittance of the electrochromic device prepared in Example 1 is demonstrated under various operating conditions within a wide wavelength range of 300 to 800 nm. The electrochromic device achieves significant optical modulation of 58.9% at 630 nm. Furthermore, through… Figure 6 As can be seen, the device is in a colored state when the applied voltage is -0.1 V, and the color is darker when the voltage is -0.3 V. This indicates that the device has already started to color when the voltage is 0 V or no voltage is applied, which confirms that the electrochromic device prepared by this invention can achieve the effect of energy saving and emission reduction.
[0027] Figure 8 The results present WO3 and Nb content measured in zinc trifluoromethanesulfonate electrolyte by linear cyclic voltammetry at a scan rate of 50 mV / s within a voltage window from -0.8 V to 0.5 V. 18 W 16 O 93 Electrode cycling stability. It can be seen that the optical contrast of the WO3 electrode tested in zinc trifluoromethanesulfonate electrolyte only retains 4.6% of its initial value after 1500 s cycling. Conversely, the Nb electrode immersed in zinc trifluoromethanesulfonate electrolyte... 18 W 16 O 93 The optical modulation range of the thin film remained almost unchanged even after 30,000 cycles, retaining more than 98% of its initial value, indicating that Nb 18 W 16 O 93 The thin film exhibits excellent cycling stability. In addition, the response time distribution of the electrochromic devices prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 18915.2 standard, and the test results are shown in Table 1: Table 1: Test results of electrochromic devices prepared in Examples 1-3 and Comparative Examples 1-4 As can be seen from the data in Table 1 above, Example 1 has a faster color-changing response than Comparative Example 1. This shows that heating carbon fibers together with sodium hydroxide increases their surface area, which helps the composite conductive material to perform better. In Comparative Example 2, the composite of functionalized carbon nanotubes and carbon fibers was omitted, resulting in a shorter response time compared to Example 1. In Comparative Example 3, the addition of the composite conductive material was completely omitted, resulting in the slowest response time. Through the comparison of the above examples and comparative examples, it can be seen that the electrochromic device in this invention has a faster response speed, and the response time difference between the edge and the middle part is smaller, resulting in a more uniform color change.
[0028] The electrochromic device prepared in this invention can be applied to fields such as smart building glass, smart displays, automotive sunroofs, and smart thermal control.
[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material, characterized in that, The preparation method includes the following steps: S1. FTO / niobium-tungsten bimetallic oxide thin films were prepared by magnetron sputtering. S2. Prepare a counter electrode thin film layer on FTO or ITO transparent conductive glass by magnetron sputtering or electrochemical deposition. S3. Prepare the electrolyte solution; S4. Apply double-sided tape around the upper surface of the FTO / niobium-tungsten bimetallic oxide film, and then attach the upper surface of the counter electrode film layer to the double-sided tape to obtain a sandwich structure. S5. Inject the electrolyte solution into the pores of the sandwich structure, and seal the edges with quick-drying adhesive to obtain the electrochromic device. The electrolyte solution in step S3 includes a composite conductive material, an electrolyte, and deionized water. The preparation method of the composite conductive material includes the following steps: S101. Grind carbon fiber together with sodium hydroxide. Then, heat the ground product at 500-600℃ for 20-40 minutes under a nitrogen atmosphere, and then raise the temperature to 700-800℃ and continue heating for 20-40 minutes. S102. Wash the carbon fiber treated in step S101 with water. After washing, add the carbon fiber to concentrated nitric acid and heat to 60-90℃ for 4-8 hours. Then filter. After further washing, dry the filtered product at 60-90℃ for 2-4 hours. S103. Disperse carbon nanotubes ultrasonically in a mixed solution of concentrated nitric acid and concentrated sulfuric acid, heat to 60-90℃ for 1-2 hours, then filter, and wash the filtered product with water. S104. The carbon nanotubes treated in step S103 are ultrasonically dispersed in an ethanol solution of 3-aminopropyltriethoxysilane and heated to 50-80℃ for 2-4 hours. After that, the mixture is filtered, the filtered product is washed with water and then dried at 60-90℃ for 2-4 hours. S105. The carbon fibers treated in step S102 and the carbon nanotubes treated in step S104 are ultrasonically dispersed in acetone. Then, sodium hydroxide solution is added dropwise to adjust the pH to 8-9. The reaction is carried out for 1-3 hours. After filtration, the filtered product is washed with water and dried at 60-90℃ for 2-4 hours to obtain the composite conductive material. The electrolyte is one of the following: ammonium salt, zinc salt, calcium salt, and aluminum salt.
2. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, The preparation of FTO / niobium-tungsten bimetallic oxide thin films by magnetron sputtering in step S1 specifically includes the following steps: S201. Place the FTO glass in acetone, alcohol, and deionized water for ultrasonic cleaning for 10 minutes each, and then dry it with a hair dryer for later use. S202. After applying vacuum tape to one side of the cleaned FTO glass front, place it on the sample stage in the vacuum chamber of the magnetron sputtering system. S203. The sputtering target material is pure tungsten metal or tungsten oxide, niobium metal or niobium oxide. The FTO glass is rotated at a constant speed of 5-12º / s for sputtering. During the sputtering process, the FTO glass is heated to 400-500℃. Before the formal sputtering, a pre-sputtering is performed for 3-5 minutes to remove contamination from the target surface. S204. After sputtering is completed and the sample has cooled for 20 minutes, open the vacuum chamber and take out the sample. Remove the vacuum tape from the sample surface and place the sample in a vacuum tube furnace for heat treatment in an argon atmosphere. After heat treatment, take out the sample and place it in a drying oven for storage, thus obtaining an FTO / niobium-tungsten bimetallic oxide film.
3. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 2, characterized in that, In step S202, the vacuum level of the vacuum chamber is evacuated to 3×10⁻⁶. -3 Below Pa, the working gas is a mixture of argon and oxygen, with a flow ratio of argon to oxygen of 1:1 to 5:1, and the working pressure is set between 1.0 and 2.5 Pa; in step S203, the power of the sputtering power supply for the tungsten metal or tungsten oxide target is set between 100 and 200 W, the power of the sputtering power supply for the niobium metal or niobium oxide target is set between 150 and 300 W, and the sputtering time is set between 10 and 60 min.
4. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, In step S101, the mass ratio between carbon fiber and sodium hydroxide is 1:(4-6).
5. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, The concentrations of concentrated nitric acid in step S102 and in step S103 are both 68 wt%, the concentration of concentrated sulfuric acid in step S103 is 98 wt%, and the volume ratio between concentrated nitric acid and concentrated sulfuric acid in step S103 is 1:
2.
6. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, In step S104, the concentration of 3-aminopropyltriethoxysilane in the ethanol solution of 3-aminopropyltriethoxysilane is 3-6 wt%.
7. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, In step S105, the mass ratio of the carbon fiber treated in step S102, the carbon nanotubes treated in step S104, and the acetone is 1:(5-10):(80-120).
8. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, The electrolyte concentration in the electrolyte solution is 5 mol / L, and the mass ratio between the composite conductive material and deionized water is 1:(10-15).
9. The method for fabricating an electrochromic device based on niobium-tungsten bimetallic oxide material according to claim 1, characterized in that, In step S2, nickel oxide and lithium manganese oxide films with a thickness of 300-800 nm are deposited on transparent conductive glass using magnetron sputtering; vanadium oxide films, manganese oxide films, polyaniline films, or Prussian blue films with a thickness of 100-1000 nm are deposited on transparent conductive glass using electrochemical deposition.
10. The electrochromic device prepared by the method of any one of claims 1-9 based on niobium-tungsten bimetallic oxide material is applied in the fields of smart building glass, smart display, automotive sunroof and smart thermal control.