Electrochromic thin film and preparation method and application thereof

Abstract

The application discloses an electrochromic film and a preparation method and application thereof, relates to the technical field of functional materials, and comprises the following steps: providing a V2O5 amorphous film; converting the V2O5 amorphous film into a lithium-containing V2O5 amorphous film by an electrochemical lithiation method with a lithium salt solution as a lithium source; and obtaining a lithium-doped z-V2O5 film by annealing the lithium-containing V2O5 amorphous film, namely the electrochromic film. The electrochromic film is prepared by the method of electrochemical lithiation combined with subsequent annealing. When a voltage load is applied to the electrochromic film prepared by the electrochemical lithiation method, there are infrared transmission or infrared blocking states, the electrochromic film reversibly changes while greatly changing the transmittance of the infrared waveband, the infrared modulation amplitude reaches 70%, and the problem that the infrared modulation amplitude of the layered V2O5 crystal film is small is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to an electrochromic thin film, its preparation method, and its application. Background Technology

[0002] Electrochromic technology provides an effective way to controllably adjust the optical properties of materials. Under the action of an electric field, the redox reactions inside electrochromic materials cause reversible changes in their valence state, composition, or phase structure, resulting in stable and reversible changes in the material's optical properties (absorption, transmittance, and reflectance, etc.) in the visible, near-infrared, and even microwave regions.

[0003] Currently, organic electrochromic materials based on organic molecules, polymers, and metal-organic frameworks offer fast response and a rich variety of colors. However, in practical applications, compared to inorganic electrochromic materials, organic electrochromic materials exhibit poorer thermal stability, light stability, chemical stability, and radiation resistance. Therefore, the high stability and durability of inorganic electrochromic materials give them a greater advantage over organic electrochromic materials in various application scenarios.

[0004] In inorganic electrochromic materials, the absorption edge of layered V₂O₅ crystalline thin films in the visible light band can shift reversibly. This shift in the optical absorption edge originates from the different band structures of the different phases resulting from a reversible phase transition. The phase transition can be controlled through stepwise ion intercalation, thereby controlling its optical properties and achieving dynamic and selective modulation of the visible and near-infrared spectra. Such optical characteristics are highly suitable for the needs of multi-mode smart windows. However, the infrared modulation amplitude of layered V₂O₅ crystalline thin films is relatively small, and achieving maximum infrared modulation would lead to an irreversible phase transition, resulting in a significant decrease in the reversibility and amplitude of the modulation, greatly limiting its applications.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electrochromic thin film, its preparation method and application, which aims to solve the problem of small infrared modulation amplitude of layered V2O5 crystal thin films.

[0007] The technical solution of the present invention is as follows:

[0008] A first aspect of the present invention provides a method for preparing an electrochromic thin film, comprising the following steps:

[0009] Provide V2O5 amorphous thin films;

[0010] Using a lithium salt solution as a lithium source, the V2O5 amorphous film is converted into a lithium-containing V2O5 amorphous film through an electrochemical lithiation method.

[0011] After annealing the lithium-containing V2O5 amorphous thin film, a lithium-doped ζ-V2O5 thin film is obtained, which is the electrochromic thin film.

[0012] Optionally, the electrochemical lithiation method is a constant current charging method.

[0013] Optionally, the process parameters used in the constant current charging method are as follows:

[0014] Current density is 10–30 μA / cm 2 The time is 200–600 s, and the lithium salt concentration is 0.5–2 mol / L.

[0015] Optionally, the lithium salt in the lithium salt solution includes at least one of lithium perchlorate, lithium hexafluorophosphate, lithium bis(oxaloyl)borate, lithium tetrafluoroborate, lithium difluorooxaloylborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, and lithium tetrafluorooxaloyl phosphate.

[0016] Optionally, the solvent in the lithium salt solution includes at least one of propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl carbonate, and diethyl carbonate.

[0017] Optionally, the annealing temperature is 250–450°C, and the annealing time is 1–5 hours.

[0018] Optionally, the method for preparing the V2O5 amorphous thin film includes the following steps:

[0019] Provide a base;

[0020] Amorphous V2O5 thin films were formed on the substrate by magnetron sputtering.

[0021] In a second aspect, the present invention provides an electrochromic thin film, wherein it is prepared by the preparation method described above.

[0022] A third aspect of the present invention provides an application of the electrochromic thin film of the present invention as described above in the field of electrochromism.

[0023] Optionally, the electrochromic thin film is used as an electrochromic material to prepare electrochromic devices.

[0024] Beneficial effects: This invention prepares an electrochromic film by combining electrochemical lithiation with subsequent annealing. When a voltage load is applied to the electrochromic film prepared by electrochemical lithiation, it exhibits either infrared transmission or infrared blocking states. The electrochromic film undergoes a reversible change while significantly altering its infrared transmittance, with an infrared modulation amplitude reaching 70%. This effectively solves the problem of the small infrared modulation amplitude (less than 60%) of layered V2O5 crystal films. Attached Figure Description

[0025] Figure 1 The image shown is a SEM image of the electrochromic thin film prepared in Example 1 of this invention, with a magnification of 20kx.

[0026] Figure 2 The image shown is a SEM image of the electrochromic thin film prepared in Example 2 of this invention, magnified at 50k times.

[0027] Figure 3 The images are XRD patterns of the electrochromic films prepared in Examples 1 to 3 of this invention.

[0028] Figure 4 These are physical images of the electrochromic thin film prepared in Example 1 of the present invention under different voltages.

[0029] Figure 5 The image shows the XRD patterns of the electrochromic thin film prepared in Example 1 of this invention under different voltage states during cyclic voltammetry.

[0030] Figure 6 The image shows the in-situ spectral transmittance curves of the electrochromic thin film prepared in Example 1 of this invention in its colored and faded states.

[0031] Figure 7 The cyclic voltammetry curves are those of the electrochromic thin film prepared in Example 4 of this invention.

[0032] Figure 8 The curve shows the change in spectral transmittance at 1100 nm of the electrochromic thin film prepared in Example 4 of this invention during electrochemical cycling. Detailed Implementation

[0033] This invention provides an electrochromic thin film, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0035] In the relationship between phase transition and transmittance change of layered crystalline V₂O₅ thin films, the phase transition process of V₂O₅ thin films is represented by α, ε, δ, γ, ω, and ω'. The phase transition in the α–γ range is reversible, but the infrared modulation of the V₂O₅ thin film (thickness 320 nm) is less than 60%. If the phase transition reaches ω', although a 70% infrared modulation amplitude can be achieved, the reversibility is poor, and the modulation amplitude is basically only 40% in the second cycle. Therefore, the infrared modulation amplitude of layered crystalline V₂O₅ thin films is small, and the infrared modulation reversibility is poor. Irreversible phase transitions cause the modulation amplitude to decay significantly with cycling, greatly limiting its applications. Therefore, improving the modulation amplitude and reversibility of V₂O₅ thin films in the infrared band is of great significance for broadening the application of electrochromic materials in energy, construction, information, and defense fields. Based on this, this invention provides a method for preparing an electrochromic thin film, comprising the following steps:

[0036] S1. Provide V2O5 amorphous thin films;

[0037] S2. Using a lithium salt solution as a lithium source, the V2O5 amorphous film is converted into a lithium-containing V2O5 amorphous film through an electrochemical lithiation method.

[0038] S3. After annealing the lithium-containing V2O5 amorphous thin film, a lithium-doped ζ-V2O5 thin film is obtained, which is the electrochromic thin film.

[0039] This invention uses a lithium salt solution as the lithium source. First, a lithium-containing V₂O₅ amorphous thin film is obtained through electrochemical lithiation. Then, a stable lithium-doped ζ-V₂O₅ thin film is prepared by annealing. Specifically, this invention uses an electrochemical lithiation method to... + It enters the amorphous V2O5 film, forming lithium-containing V2O5 (which can also be represented as Li). x V₂O₅, where x represents the number of Li atoms (e.g., x:2 represents the ratio of Li atoms to V atoms or molar ratio). In amorphous thin films, further annealing... + On the one hand, it affects the crystallization behavior of V₂O₅, causing it to transform into ζ-V₂O₅; on the other hand, Li + By embedding lithium into the channel structure of ζ-V₂O₅, ζ-V₂O₅ (which can also be represented as ζ-Li) with lithium embedded in the channel is obtained. x The ζ-V2O5 thin film is a lithium-doped ζ-V2O5 thin film.

[0040] When a voltage load is applied to the electrochromic thin film prepared by the electrochemical lithiation method of this invention, it exhibits either infrared transmission or infrared blocking states. The electrochromic thin film undergoes a reversible change while significantly altering its infrared transmittance, achieving an infrared modulation amplitude of 70% (for a thickness of 320 nm). Furthermore, after 50 cycles, the modulation amplitude still reaches 63%, effectively solving the problems of low infrared modulation amplitude (less than 60% in the first cycle for a thickness of 320 nm) and poor phase transition reversibility (only 40% modulation amplitude in the second cycle for a thickness of 320 nm). The electrochromic thin film provided by this invention has broad application prospects in the field of electrochromism.

[0041] The electrochromic film described in this embodiment of the invention undergoes a phase transition when ions (including but not limited to lithium ions) are implanted or extracted. Different phases have different polaron transition modes, resulting in different optical absorption, thereby enabling light to pass through or be blocked.

[0042] In step S1, in some embodiments, the method for preparing the V2O5 amorphous thin film includes the following steps:

[0043] S11, Provide the substrate;

[0044] S12. An amorphous V2O5 thin film is formed on the substrate by magnetron sputtering.

[0045] In step S1, the substrate is a conductive substrate, specifically, it can be indium tin oxide conductive glass (ITO), fluorine-doped tin dioxide conductive glass (FTO), etc., but is not limited to these.

[0046] In step S2, in one embodiment, forming a V2O5 amorphous thin film on the substrate by magnetron sputtering specifically includes the following steps:

[0047] Using vanadium as the target material, a V2O5 amorphous thin film is formed on the substrate by magnetron sputtering in an oxygen and argon atmosphere.

[0048] Specifically, the sputtering power and sputtering pressure used in magnetron sputtering can be set according to actual needs.

[0049] This invention combines the magnetron sputtering method described in this embodiment with the electrochemical lithiation method described above to prepare a stable photochromic thin film.

[0050] In step S2, in some embodiments, the electrochemical lithiation method is a constant current charging method.

[0051] In some implementations, the process parameters used in the constant current charging method are as follows:

[0052] Current density is 10–30 μA / cm2 The time is 200–600 s, and the lithium salt concentration is 0.5–2 mol / L.

[0053] By controlling the current density, time, and lithium salt concentration, the transformation of V2O5 amorphous film into ζ-V2O5 is ensured, while the amount of lithium embedded in the ζ-V2O5 channel is controlled, ultimately forming a lithium-doped ζ-V2O5 film.

[0054] For example, the current density can be 10 μA / cm. 2 11μA / cm 2 12μA / cm 2 13μA / cm 2 14μA / cm 2 15μA / cm 2 16μA / cm 2 17μA / cm 2 18μA / cm 2 19μA / cm 2 20μA / cm 2 21μA / cm 2 22μA / cm 2 23μA / cm 2 24μA / cm 2 25μA / cm 2 26μA / cm 2 27μA / cm 2 28μA / cm 2 29μA / cm 2 or 30μA / cm 2 wait.

[0055] The time can be 200s, 210s, 220s, 230s, 240s, 250s, 260s, 270s, 280s, 290s, 300s, 310s, 320s, 330s, 340s, 350s, 360s, 370s, 380s, 390s, 400s, 410s, 420s, 430s, 440s, 450s, 460s, 470s, 480s, 490s, 500s, 510s, 520s, 530s, 540s, 550s, 560s, 570s, 580s, 590s, or 600s, etc.

[0056] The lithium salt concentration can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, or 2 mol / L, etc.

[0057] Specifically, a three-electrode system is adopted, using metallic lithium as the reference and counter electrode, a V₂O₅ amorphous thin film as the working electrode, and a lithium salt solution as the lithium source. A constant current charging method is used, with a current of 10–30 μA / cm. 2 The Li was prepared by constant current charging for 250–500 s at a current density of [specific value]. x V2O5 amorphous thin films. Using these process parameters, higher quality lithium-containing V2O5 amorphous thin films can be prepared.

[0058] In some embodiments, the current density is 20 μA / cm². 2 The annealing time is 400±30s (e.g., 370s, 380s, 390s, 400s, 410s, 420s, or 430s, etc.) to obtain a lithium-containing V₂O₅ amorphous thin film. After subsequent annealing, a lithium-doped ζ-V₂O₅ thin film, i.e., the electrochromic thin film, is obtained, wherein the molar number of Li accounts for 30% of the molar number of ζ-V₂O₅.

[0059] In some embodiments, the lithium salt in the lithium salt solution includes at least one of lithium perchlorate, lithium hexafluorophosphate (LiPF6), lithium bis(oxaloyl)borate (LiBOB), lithium tetrafluoroborate (LiBF4), lithium difluorooxaloylborate (LiODFB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorophosphate (LiPO2F2), and lithium tetrafluorooxaloyl phosphate (LiFOP), but is not limited thereto.

[0060] In some embodiments, the solvent in the lithium salt solution includes at least one of propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl carbonate, and diethyl carbonate, but is not limited thereto.

[0061] In some embodiments, the annealing temperature is 250–450°C, and the annealing time is 1–5 hours. Specifically, the annealing temperature can be 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, or 450°C, etc. The annealing time can be 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours, etc. An annealing temperature of 250–450°C and an annealing time of 1–5 hours can ensure sufficient crystallization of the lithium-containing V₂O₅ amorphous thin film, thereby facilitating the preparation of high-quality lithium-doped ζ-V₂O₅ thin films.

[0062] The present invention does not limit the thickness of the electrochromic film prepared by the above preparation method, and can select it according to actual needs. For example, the thickness of the electrochromic film is 200-400 nm, specifically, it can be 200 nm, 250 nm, 300 nm, 350 nm or 400 nm, etc.

[0063] Because the modulation of transmittance of a thin film is positively correlated with its thickness, a thicker film will have a larger modulation amplitude. Simultaneously, a greater thickness results in lower initial transmittance (less transparency). Therefore, the embodiments of this invention employ the thickness described above, ensuring both sufficient transmittance and a large modulation amplitude. Furthermore, process stability must also be considered. If the film thickness is less than 200 nm, uniform lithiation cannot be guaranteed, and lithium-ion implantation may primarily occur on the surface. The process parameters used in this invention are suitable for films of this thickness.

[0064] This invention also provides an electrochromic thin film, which is prepared using the preparation method described above.

[0065] The electrochromic thin film provided in this embodiment can significantly adjust the transmittance of the near-infrared band of the thin film while regulating its reversible changes. Therefore, applying the electrochromic thin film to the field of electrochromism solves the problem of poor infrared modulation reversibility of layered crystal V2O5. Furthermore, the electrochromic thin film itself contains a certain amount of lithium, which allows it to provide a certain amount of lithium to the counter electrode material when used in the fabrication of electrochromic devices, further broadening the application range of the electrochromic thin film. Specifically, when selecting the counter electrode material for electrochromism, not only the matching of the electrochemical window but also the ion requirements of the counter electrode material must be considered. If the material requires a large amount of ion implantation to achieve color change, but the electrolyte contained in the device is limited, its performance will be affected. During ion implantation of the electrode material, the lithium ions contained in the electrochromic thin film provided by this invention can enter the electrolyte, supplementing the lithium content and resulting in better device performance.

[0066] This invention also provides an application of the electrochromic thin film described above in the field of electrochromism.

[0067] In some embodiments, the electrochromic thin film is used as an electrochromic material to prepare electrochromic devices.

[0068] The present invention will be further described below through specific embodiments.

[0069] This invention provides a method for preparing an electrochromic thin film, comprising the following steps:

[0070] (1) Provide commercial ITO, clean it, and use it as a substrate;

[0071] (2) Using magnetron sputtering, pure vanadium (99.99%) target material was sputtered on the substrate for 120 minutes under the conditions of oxygen-argon volume ratio of 1:9, sputtering pressure of 1 Pa and power of 150 W to obtain a V2O5 amorphous thin film with a thickness of 350 nm.

[0072] (3) The V2O5 amorphous thin film obtained in step (2) was placed in a glove box and subjected to electrochemical lithiation using an electrochemical workstation with a three-electrode system. The V2O5 amorphous thin film was used as the working electrode, and a lithium metal sheet was used as the reference and counter electrode. A 1 mol / L lithium perchlorate propylene carbonate solution was used as the lithium source. Lithiation was performed using a constant current charging method with a current density of 20 μA / cm². 2 The lithiation time was 400s to obtain a lithium-containing V2O5 amorphous transparent film (attached to ITO), which was then rinsed with dimethyl carbonate and dried with a nitrogen gun.

[0073] (4) The lithium-containing V2O5 amorphous transparent film obtained in step (3) is annealed at 300°C for 2 hours to obtain a lithium-doped ζ- V2O5 film, i.e. an electrochromic film with a thickness of 320 nm.

[0074] The surface morphology (i.e., SEM image) of the electrochromic thin film in Example 1 is as follows: Figure 1 As shown.

[0075] Example 2

[0076] This embodiment provides a method for preparing an electrochromic thin film, including the following steps:

[0077] (1) Provide commercial ITO, clean it, and use it as a substrate;

[0078] (2) Using magnetron sputtering, pure vanadium (99.99%) target material was sputtered on the substrate for 120 minutes under the conditions of oxygen-argon volume ratio of 1:9, sputtering pressure of 1 Pa and power of 150 W to obtain a V2O5 amorphous thin film with a thickness of 350 nm.

[0079] (3) The V2O5 amorphous thin film obtained in step (2) was placed in a glove box and subjected to electrochemical lithiation using an electrochemical workstation with a three-electrode system. The V2O5 amorphous thin film was used as the working electrode, and a lithium metal sheet was used as the reference and counter electrode. A 1 mol / L lithium perchlorate propylene carbonate solution was used as the lithium source. Lithiation was performed using a constant current charging method with a current density of 20 μA / cm². 2 The lithiation time was 380s to obtain a lithium-containing V2O5 amorphous transparent film (attached to ITO), which was then rinsed with dimethyl carbonate and dried with a nitrogen gun.

[0080] (4) The lithium-containing V2O5 amorphous transparent film obtained in step (3) is annealed at 300°C for 2 hours to obtain a lithium-doped ζ-V2O5 film, i.e. an electrochromic film with a thickness of 320 nm.

[0081] The surface morphology (i.e., SEM image) of the electrochromic thin film in Example 2 is as follows: Figure 2 As shown.

[0082] Example 3

[0083] This embodiment provides a method for preparing an electrochromic thin film, including the following steps:

[0084] (1) Provide commercial ITO, clean it, and use it as a substrate;

[0085] (2) Using magnetron sputtering, pure vanadium (99.99%) target material was sputtered on the substrate for 120 minutes under the conditions of oxygen-argon volume ratio of 1:9, sputtering pressure of 1 Pa and power of 150 W to obtain a V2O5 amorphous thin film with a thickness of 350 nm.

[0086] (3) The V2O5 amorphous thin film obtained in step (2) was placed in a glove box and subjected to electrochemical lithiation using an electrochemical workstation with a three-electrode system. The V2O5 amorphous thin film was used as the working electrode, and a lithium metal sheet was used as the reference and counter electrode. A 1 mol / L lithium perchlorate propylene carbonate solution was used as the lithium source. Lithiation was performed using a constant current charging method with a current density of 20 μA / cm². 2 The lithiation time was 420s to obtain a lithium-containing V2O5 amorphous transparent film (attached to ITO), which was then rinsed with dimethyl carbonate and dried with a nitrogen gun.

[0087] (4) The lithium-containing V2O5 amorphous transparent film obtained in step (3) is annealed at 300°C for 2 hours to obtain a lithium-doped ζ-V2O5 film, i.e. an electrochromic film with a thickness of 320 nm.

[0088] test:

[0089] The XRD results of the electrochromic films in Examples 1-3 are as follows: Figure 3 As shown, Figure 3 The two diffraction peaks appearing at 9.2° and 12.4° correspond to Li, respectively. 0.3 The (001) and (200) crystal planes of V2O5 (Li 0.3 The standard PDF card number for V2O5 is 04-006-0889.

[0090] The electrochromic properties of the electrochromic thin film prepared in Example 1 were tested:

[0091] 1) Cyclic voltammetry was used to scan the electrochromic thin film, with a voltage range of 2.25-4.00V and a scan rate of 1mV / s. The color change of the film immersed in the solution under different voltages during the scanning process was observed as follows: Figure 4 As shown, the film exhibits different colors under different voltages.

[0092] 2) Cyclic voltammetry was used to capture the in-situ spectral transmittance changes in the colored and faded states. The XRD patterns at different voltages during the cyclic voltammetry test are shown below. Figure 5 As shown, during ion implantation and extraction, the electrochromic thin film only undergoes ion intercalation (without phase transition) at voltages greater than 2.6 eV, while a phase transition process occurs between 2.3 and 2.6 eV.

[0093] 3) The in-situ spectral transmittance change curves of its colored and faded states are as follows: Figure 6 As shown, when a voltage load is applied to the electrochromic film, there are states of infrared transmission or infrared blocking.

[0094] 4) Cyclic voltammetry was used, with a cycle range of 2.2–3.2 V and a scan rate of 1 mV / s, for 50 cycles. The changes in the electrochemical cyclic voltammetry curves were recorded, and the results are as follows: Figure 7 As shown, the variation of spectral transmittance at 1100 nm during its electrochemical cycling process was recorded in situ, and the results are as follows. Figure 8 As shown, the electrochromic film switches between different infrared transmittances and has good stability. After one cycle, the infrared modulation amplitude is 70%, and after 50 cycles, the modulation amplitude is 63%.

[0095] Comparative Example 1

[0096] This comparative example provides a method for preparing a thin film, which differs from Example 1 only in that the current density is 35 μA / cm². 2 The lithiation time is 650s.

[0097] The film prepared in this comparative example does not have the infrared modulation amplitude of the film described in Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a method for preparing a thin film, which differs from Example 1 only in that the current density is 8 μA / cm. 2 The lithiation time is 150s.

[0100] The film prepared in this comparative example does not have the infrared modulation amplitude of the film described in Example 1.

[0101] In summary, this invention provides an electrochromic thin film, its preparation method, and its applications. The electrochromic thin film is prepared by electrochemical lithiation combined with subsequent annealing. When a voltage load is applied to the electrochromic thin film prepared by electrochemical lithiation, it exhibits either infrared transmission or infrared blocking states. The electrochromic thin film undergoes a reversible change while significantly altering its infrared transmittance, achieving an infrared modulation amplitude of 70%, effectively solving the problem of the relatively small infrared modulation amplitude (less than 60%) of layered V₂O₅ crystal thin films. Furthermore, the electrochromic thin film itself contains a certain amount of lithium, enabling it to provide a certain amount of lithium for the counter electrode material when used in the fabrication of electrochromic devices, further broadening the application range of the electrochromic thin film. The electrochromic thin film provided by this invention has broad application prospects.

[0102] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a lithium-doped ζ-V₂O₅ thin film, characterized in that, Includes the following steps: Provide V2O5 amorphous thin films; Using a lithium salt solution as a lithium source, the V2O5 amorphous film is converted into a lithium-containing V2O5 amorphous film through an electrochemical lithiation method. After annealing the lithium-containing V₂O₅ amorphous thin film, Li + Amorphous V₂O₅ is converted into ζ-V₂O₅, while Li + The lithium-doped ζ-V2O5 film was obtained by embedding it into the channel of ζ-V2O5. The electrochemical lithiation method is a constant current charging method; The process parameters used in the constant current charging method are as follows: Current density is 10~30 μA / cm 2 The time was 200~600 s, and the lithium salt concentration was 0.5~2 mol / L; The annealing temperature is 250~450℃, and the annealing time is 1~5 h; The solvent in the lithium salt solution includes at least one of propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl carbonate, and diethyl carbonate.

2. The preparation method according to claim 1, characterized in that, The lithium salt in the lithium salt solution includes at least one of lithium perchlorate, lithium hexafluorophosphate, lithium bis(oxaloyl)borate, lithium tetrafluoroborate, lithium difluorooxaloylborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, and lithium tetrafluorooxaloyl phosphate.

3. The preparation method according to claim 1, characterized in that, The method for preparing the V2O5 amorphous thin film includes the following steps: Provide a base; Amorphous V2O5 thin films were formed on the substrate by magnetron sputtering.

4. A lithium-doped ζ-V₂O₅ thin film, characterized in that, It is prepared by the preparation method described in any one of claims 1-3.

5. The application of the lithium-doped ζ-V₂O₅ thin film of claim 4 in the field of electrochromism.

6. The application according to claim 5, characterized in that, The lithium-doped ζ-V2O5 thin film is used as an electrochromic material to prepare electrochromic devices.

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