CN118897426A - An electrochromic/capacitive dual-function thin film material and its preparation method and application - Google Patents

Abstract

The invention discloses an electrochromic/capacitive dual-function film material, a preparation method and application thereof, and belongs to the technical field of functional film materials. The film material comprises: a titanium dioxide surface layer with the thickness of 20-40 nm, a tungsten trioxide middle layer with the thickness of 150-210 nm and a metal tungsten bottom layer with the thickness of 20-40 nm. The capacity of the electrochromic/capacitive dual-function film material reaches 20.2-51.5 mF/cm ², and the capacitance multiplying power performance reaches 58.7-88.6%; and the process of coloring and fading of multiple colors can be reversibly generated, the complete coloring and fading time is short, the visible light modulation amplitude can reach 75% at most, the coloring efficiency is 42.3-74.2 cm ²/C, and the quantity of the electric quantity stored in the film can be intuitively and quantitatively judged through the color type change of the film in the process of charging and discharging.

Description

An electrochromic/capacitive dual-function thin film material and its preparation method and application

Technical Field

The invention belongs to the technical field of functional thin film materials, and in particular relates to an electrochromic/capacitive dual-functional thin film material and a preparation method and application thereof.

Background Art

The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not be necessarily regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

Electrochromic materials have attracted much attention due to their tunable and reversible optical properties (transmittance, absorbance or reflection) under low voltage drive, and are promising materials in many aspects. Pseudocapacitors can store energy by inserting/extracting charges through reversible redox reactions, and are considered to be another promising energy storage technology development direction besides batteries. When a reversible redox reaction with rapid charge transfer occurs in a pseudocapacitor, certain specific electrode materials will undergo an electrochromic process at the same time, including tungsten trioxide materials.

However, in the prior art, the solution of adding a titanium dioxide layer on the surface of the tungsten trioxide material can only achieve a change in the depth or transparency of a single color, and the distinction is not high.

Summary of the invention

In view of the shortcomings of the prior art, the purpose of the present invention is to provide an electrochromic/capacitive dual-function thin film material and its preparation method and application, which utilizes the inherent properties of inorganic materials tungsten trioxide and titanium dioxide, adds a reflective layer of tungsten material, and prepares a graded layered structure, which can effectively improve the electron transmission speed and ion diffusion rate, accelerate the reaction kinetics process, and not only achieve a rich change in color types and improve color differentiation, but also realize the energy storage function and greatly improve the reaction speed and cycle stability of the electrochromic capacitor dual-function material.

In order to achieve the above object, the technical solution of the present invention is:

In the first aspect, an electrochromic/capacitive dual-function thin film material includes: a titanium dioxide surface layer with a thickness of 5 to 40 nm, a tungsten trioxide middle layer with a thickness of 150 to 210 nm, and a metal tungsten bottom layer with a thickness of 20 to 40 nm; and the metal tungsten, tungsten trioxide and titanium dioxide are all amorphous.

Optionally, the metal tungsten bottom layer is located on a conductive substrate, and the conductive substrate is ITO conductive glass.

In a second aspect, the method for preparing the above-mentioned electrochromic/capacitive dual-function thin film material comprises the following steps:

S1. Using metal tungsten as a target, DC deposition sputtering is performed on the surface of a conductive substrate to obtain a metal tungsten bottom layer of a set thickness;

S2, using metal tungsten as a target, in an oxygen-containing atmosphere, performing DC reactive deposition sputtering on the surface of the metal tungsten bottom layer to obtain a tungsten trioxide intermediate layer of a set thickness;

S3. Using titanium dioxide as a target, radio frequency deposition sputtering is performed on the surface of the tungsten trioxide intermediate layer to obtain a titanium dioxide surface layer of a set thickness.

Optionally, in S1, W with a purity of 99.99% or more is used as the target material.

Optionally, in S1, direct current deposition sputtering is performed in an argon atmosphere in a chamber with a vacuum degree of less than 6×10 ^-4 Pa.

Optionally, in S1, during the DC deposition sputtering process, the gas flow rate of argon is 15-25 sccm, the sputtering power is 80-120 W, the sputtering pressure is 0.2-0.25 Pa, the sputtering time is 3-5 min, and the working distance is 10-12 cm.

Optionally, in S2, W with a purity of 99.99% or more is used as the target material.

Optionally, in S2, direct current reactive deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa in a mixed atmosphere of oxygen and argon in a volume ratio of 1:(2.5-3).

Optionally, in S2, during the DC reactive deposition sputtering process, the gas flow rate of argon is 25-30 sccm, the gas flow rate of oxygen is 10-12 sccm, the sputtering power is 80-120 W, the sputtering gas pressure is 0.3-0.35 Pa, the sputtering time is 15-18 min, and the working distance is 10-12 cm.

Optionally, in S3, radio frequency deposition sputtering is performed in an argon atmosphere in a chamber with a vacuum degree of less than 6×10 ^-4 Pa.

Optionally, in S3, TiO2 with a purity of 99.99% or more is used as the target material.

Optionally, in S3, during the RF deposition sputtering process, the gas flow rate of argon is 15 to 25 sccm, the sputtering power is 80 to 120 W, the sputtering pressure is 0.2 to 0.25 Pa, the sputtering time is 8 to 10 min, and the working distance is 10 to 12 cm.

In a third aspect, the application of the above-mentioned electrochromic/capacitive dual-function thin film material includes: application in color-changing energy storage devices.

During the charging and discharging process, the amount of electricity stored in the film material can be intuitively and quantitatively judged by the change in the color type of the film. Compared with the change in color depth or transparency, the color distinction is significantly improved.

The beneficial effects of the present invention are:

1. The electrochromic/capacitive dual-function thin film material provided by the present invention has a layered structure. On a conductive substrate such as ITO conductive glass, three layers are deposited in sequence, with metal tungsten as a reflective layer, tungsten trioxide as an intermediate color-changing layer, and titanium dioxide as a surface layer. It can reversibly undergo a coloring and fading process from the initial purple to brown, dark brown, green, dark green and other colors during the reversible storage and release of electricity. It has excellent electrochromic performance, a short time for complete coloring and fading, a visible light modulation amplitude of up to 75%, and a coloring efficiency of 42.3 to 74.2 ^cm2 /C. During the charging and discharging process, the amount of electricity stored in the thin film material can be intuitively and quantitatively judged by the change in the color type of the film, which significantly improves the color distinction compared to the change in color depth or transparency.

2. In the preparation method of the electrochromic/capacitive dual-function thin film material provided by the present invention, each layer is prepared by magnetron sputtering. The method is simple, stable, and has controllable size and thickness. It is compatible with the existing commercial standard electrochromic process and is conducive to large-scale industrial production.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

FIG. 1 is a scanning electron microscope image in Example 1.

FIG. 2 is a diagram showing the XRD analysis results in Example 1.

FIG. 3 is a diagram showing the HRTEM analysis results in Example 1.

FIG. 4 is a reflection spectrum diagram of the thin film material in Example 1.

FIG5 is a reflection spectrum diagram of the thin film material under different voltages in Example 1.

Figure 6 is a color diagram of the thin film material under different voltages in Example 1; (a) is the color change diagram corresponding to 0.1V, (b) is the color change diagram corresponding to 0.0V, (c) is the color change diagram corresponding to -0.1V, (d) is the color change diagram corresponding to -0.2V, (e) is the color change diagram corresponding to -0.3V, (f) is the color change diagram corresponding to -0.4V, (g) is the color change diagram corresponding to -0.5V, and (h) is the CIE color coordinate diagram.

FIG. 7 is a graph showing the electrochromic coloring efficiency in Example 1.

FIG. 8 is a graph showing the timing current in Example 1.

FIG. 9 is a graph showing the surface capacitance corresponding to different current densities in Example 1.

FIG. 10 is a charge and discharge curve diagram of Example 1.

FIG. 11 is a graph showing the surface capacitance corresponding to different current densities in Example 2.

Figure 12 is a graph showing the electrochromic coloring efficiency in Comparative Example 1.

FIG13 is a graph showing the surface capacitance corresponding to different current densities in Comparative Example 1.

Figure 14 is a color change diagram of the thin film material under different voltages in Comparative Example 2; (a) is the color change diagram corresponding to 0.0V, (b) is the color change diagram corresponding to -0.1V, (c) is the color change diagram corresponding to -0.2V, (d) is the color change diagram corresponding to -0.3V, (e) is the color change diagram corresponding to -0.4V, and (f) is the color change diagram corresponding to -0.5V.

DETAILED DESCRIPTION

It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and/or combinations thereof.

Example 1

An electrochromic/capacitive dual-function thin film material, the preparation method of which comprises:

S1. Using W with a purity of more than 99.99% as the target material and ITO conductive glass as the conductive substrate, DC deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa. During the DC deposition sputtering process, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 5min, and the working distance is 10cm to obtain a metal tungsten bottom layer.

S2. Using W with a purity of more than 99.99% as the target material, DC reactive deposition sputtering is performed on the metal tungsten bottom layer. The DC reactive deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa, using an oxygen-argon mixed atmosphere, with an argon gas flow rate of 30 sccm, an oxygen gas flow rate of 10 sccm, a sputtering power of 100 W, a sputtering pressure of 0.3 Pa, a sputtering time of 18 min, and a working distance of 10 cm to obtain a tungsten trioxide intermediate layer.

S3. Using _TiO2 with a purity of more than 99.99% as the target material, radio frequency deposition sputtering is performed on the tungsten trioxide intermediate layer. The protective atmosphere of the radio frequency deposition sputtering is argon, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 10min, and the working distance is 10cm to obtain a titanium dioxide surface layer.

The ITO conductive glass was ultrasonically cleaned in acetone, ethanol and deionized water for 20 minutes in sequence before use, and then dried in a vacuum oven for later use.

Through the above steps S1 to S3, an electrochromic/capacitive dual-function thin film material is obtained. The surface of the obtained electrochromic/capacitive dual-function thin film material is scanned by electron microscope. The obtained image is shown in Figure 1. The surface is flat and dense without obvious defects such as cracks.

The cross section of the obtained electrochromic/capacitive dual-function thin film material was subjected to XRD analysis. The results are shown in FIG2 , indicating that W, WO ₃ and TiO ₂ were successfully deposited on the surface of the ITO glass, and that W, WO ₃ and TiO ₂ were all in an amorphous state.

The cross section of the obtained electrochromic/capacitive dual-function thin film material was subjected to high-resolution transmission electron microscopy (HRTEM) analysis. The obtained image is shown in Figure 3, which shows that the thin film material has layered characteristics, and the thickness of the metal tungsten bottom layer is 30nm, the thickness of the tungsten trioxide middle layer is 180nm, and the thickness of the titanium dioxide surface layer is 10nm.

The obtained electrochromic/capacitive dual-function film sample was analyzed for reflectance spectrum in the visible light band using an Avantis fiber optic spectrometer. The results are shown in Figure 4. The metal layer caused the film sample to produce obvious interference resonance in the wavelength range of 380-780 nm, with two interference peaks and one interference valley. Therefore, it is known that certain wavelengths of light are absorbed by the film material, while the rest of the light is selectively reflected to the surface of the film material.

The obtained electrochromic/capacitive dual-function thin film material was used as the working electrode, the silver/silver chloride electrode was used as the reference electrode, and the platinum sheet electrode was used as the counter electrode. The following detection was performed using an electrochemical workstation.

Using the constant potential polarization method, the prepared electrochromic/capacitive dual-function film samples were applied with voltages of 0.1 to -0.5 V, including 0.1, 0.0, -0.1, -0.2, -0.3, -0.4 and -0.5 V, and the color of the film material was observed to change. During the color change process, the reflectance spectrum of the material is shown in Figure 5. The reflectance spectrum shows an obvious red shift at the peak position, from 740 nm to 550 nm, thus achieving a very large modulation range (amplitude reaches 190 nm). The color photos of the corresponding objects are shown in (a) to (g) in Figure 6: the color of the sample changes from the initial purple to brown, dark brown, green, dark green and other colors, showing a rich change in color types. The corresponding color CIE coordinate diagram is shown in the scattered points of (h) in Figure 6. The arrow in (h) of Figure 6 indicates the color change trend during the application of a voltage of 0.1 to -0.5 V. As the arrow points, the scattered points correspond to the voltage values of 0.1, 0.0, -0.1, -0.2, -0.3, -0.4 and -0.5 V in Figure 5. It can be seen that the color of the sample switches from the initial lavender to pink, rose red, light yellow, light green and other colors, showing a rich change in color types.

(a) to (g) in Figure 6 are photos of real objects, which are the colors under diffuse reflection conditions. The colors are similar to those observed with the naked eye. (h) in Figure 6 is a CIE coordinate diagram. The reflected light during the test is stronger, so the test results are different from the colors observed with the naked eye, but both reflect the changes in multiple color types.

The electrochromic coloring efficiency of the prepared electrochromic/capacitive dual-function film sample was tested, and the electrochromic coloring efficiency (CE) was calculated as follows:

;

Where ΔQ is the amount of charge inserted or extracted per unit area of the electrochromic material, ΔOD is the change in optical density, _Rb is the reflectivity in the bleached state, and _Rc is the reflectivity in the colored state. CE can be evaluated by the slope of the ΔOD vs. ΔQ graph. The electrochromic coloring efficiency test results of the electrochromic/capacitive dual-function film sample are shown in Figure 7, and the coloring efficiency is as high as 74.2 ^cm2 /C.

The switching dynamics of the electrochromic/capacitive dual-function film sample were studied by chronoamperometry. The initial potential step was set to -0.5 V and the final potential step was set to 0.5 V. The results are shown in Figure 8. In the time range of 0 to 2 s, the current dropped from 54.5 mA/cm ² to 0 mA/cm ² , and in the time range of nearly 4 s, the current rose from -27 mA cm ⁻² to 0 mAcm ⁻² , indicating that the electrochromic/capacitive dual-function film sample has a higher H ⁺ insertion/deinsertion rate.

The prepared electrochromic/capacitive dual-function film samples were tested at different current densities by constant current polarization method to obtain the surface capacitance of the electrochromic/capacitive dual-function film samples at different current densities. The results are shown in Figure 9. The surface capacitance gradually decreases with the increase of discharge current density, and even at a current density of 1 mA/ ^cm2 , it still maintains 63.1% of the maximum capacitance, further confirming the excellent rate performance of the electrochromic/capacitive dual-function film samples.

The prepared electrochromic/capacitive dual-function film sample was subjected to a charge and discharge test at a current density of 0.1 mA/cm ² by a constant current charge and discharge method. The result is shown in FIG10 , and the obtained discharge surface capacitance reaches 51.5 mF/cm ² .

The electrochromic/capacitive dual-function thin film material obtained in Example 1 was charged using a constant voltage polarization method to obtain current-time data during the charging process. The charging state (surface charge capacity) of the thin film material was calculated based on the current-time data and the size of the electrochromic/capacitive dual-function thin film material, and the color change was observed with the naked eye: when the electrochromic/capacitive dual-function thin film sample was charged at a voltage of -0.1V, the surface charge capacity was 0.00117C/ ^cm2 , and the thin film sample was brown; when the electrochromic/capacitive dual-function thin film sample was charged at a voltage of -0.2V, the surface charge capacity was 0.00246C/ ^cm2 , and the thin film sample was dark brown; when the electrochromic/capacitive dual-function thin film sample was charged at a voltage of -0.3V, the surface charge capacity was 0.00337C/ ^cm2 , and the thin film sample was green; when the electrochromic/capacitive dual-function thin film sample was charged at a voltage of -0.4V, the surface charge capacity was 0.00537C/ ^cm2 , the film sample appears dark green. That is, as the energy storage increases, the color changes from purple to brown, dark brown, green, dark green, etc. When the CIE coordinates are used for analysis, the detection result corresponding to (g) in Figure 6 can be obtained.

It can be seen from the above test results that when the thin film material prepared in the embodiment is applied to energy storage devices (surface capacitance), a fast reaction process can be achieved and for larger ion capacity, the presence of the layered structure is beneficial to the reaction kinetics, and can well buffer the volume change of the electrode during the redox reaction, which is beneficial to the cyclic stability of the material; the thin film material has a wide range of modulation in the visible band, a short reaction time, and a high coloring efficiency; at the same time, it has the characteristics of large capacity and high rate in terms of capacitance; the excellent dual-functional performance is very beneficial to the preparation of energy-saving energy storage devices.

Example 2

An electrochromic/capacitive dual-function thin film material, the preparation method of which comprises:

S1. Using W with a purity of more than 99.99% as the target material and ITO conductive glass as the conductive substrate, DC deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa. During the DC deposition sputtering process, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 5min, and the working distance is 10cm to obtain a metal tungsten bottom layer.

S2. Using W with a purity of more than 99.99% as the target material, DC reactive deposition sputtering is performed on the metal tungsten bottom layer. The DC reactive deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa, using an oxygen-argon mixed atmosphere, with an argon gas flow rate of 30 sccm, an oxygen gas flow rate of 10 sccm, a sputtering power of 100 W, a sputtering pressure of 0.3 Pa, a sputtering time of 18 min, and a working distance of 10 cm to obtain a tungsten trioxide intermediate layer.

S3. Using _TiO2 with a purity of more than 99.99% as the target material, radio frequency deposition sputtering is performed on the tungsten trioxide intermediate layer. The protective atmosphere of the radio frequency deposition sputtering is argon, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 20min, and the working distance is 10cm to obtain a titanium dioxide surface layer.

The ITO conductive glass was ultrasonically cleaned in acetone, ethanol and deionized water for 10 min in sequence before use, and then dried in a vacuum oven for later use.

The difference between the preparation method of this embodiment and that of embodiment 1 is that in S3, the sputtering time is 20 minutes, which is twice as long as that of embodiment 1.

It was detected that the thin film material prepared in this embodiment has a layered characteristic, and the thickness of the metal tungsten bottom layer is 30nm, the thickness of the tungsten trioxide middle layer is 180nm, and the thickness of the titanium dioxide surface layer is 20nm.

The thin film material prepared in this embodiment was tested according to the method of embodiment 1. The results showed that the visible light modulation of the thin film material reached 87.5%, the reaction time was short, the coloring efficiency was high (42.3 cm ² /C), the capacity was large (20.2 mF/cm ² ), and the capacitance ratio was high (88.6%).

In particular, the surface capacitance diagram of the material under different current densities is shown in Figure 11. The surface capacitance gradually decreases with the increase of discharge current density, and even at a current density of 1 mA/ ^cm2 , it still maintains 88.6% of the maximum capacitance, further confirming the excellent rate performance of the electrochromic/capacitive dual-function film sample, which is very beneficial for the preparation of energy-saving energy storage devices.

Comparative Example 1:

A thin film material, the preparation method of which comprises:

S1. Using W with a purity of more than 99.99% as the target material and ITO conductive glass as the conductive substrate, DC deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa. During the DC deposition sputtering process, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 5min, and the working distance is 10cm to obtain a metal tungsten bottom layer.

S2. Using W with a purity of more than 99.99% as the target material, DC reactive deposition sputtering is performed on the metal tungsten bottom layer. The DC reactive deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa, using an oxygen-argon mixed atmosphere, with an argon gas flow rate of 30 sccm, an oxygen gas flow rate of 10 sccm, a sputtering power of 100 W, a sputtering pressure of 0.3 Pa, a sputtering time of 18 min, and a working distance of 10 cm to obtain a tungsten trioxide intermediate layer.

The ITO conductive glass was ultrasonically cleaned in acetone, ethanol and deionized water for 10 min in sequence before use, and then dried in a vacuum oven for later use.

The difference between the preparation method of this comparative example and that of Example 1 is that no titanium dioxide layer is prepared.

It was detected that the thin film material prepared in this comparative example had a layered characteristic, and the thickness of the metal tungsten bottom layer was 30 nm, and the thickness of the tungsten trioxide layer was 180 nm.

The thin film material prepared in this comparative example was tested according to the method of Example 1. The results showed that the thin film material had low coloring efficiency (40.0 cm ² /C) and large capacity (40.8 mF/cm ² ), but the capacitance ratio could only reach (58.7%).

The electrochromic coloring efficiency of the electrochromic/capacitive dual-function film sample prepared in this comparative example was tested. The test result of the electrochromic coloring efficiency of the electrochromic/capacitive dual-function film sample is shown in FIG12 . The coloring efficiency CE was 40.0 cm ² /C.

By means of constant current polarization method, the prepared electrochromic/capacitive dual-function film samples were tested at different current densities in this comparative example to obtain the surface capacitance of the electrochromic/capacitive dual-function film samples at different current densities. The results are shown in FIG13 . The surface capacitance gradually decreases with the increase of the discharge current density, and maintains 58.7% of the maximum capacitance at a current density of 1 mA/cm ² .

Comparative Example 2

A thin film material, the preparation method of which comprises:

S1. Using W with a purity of more than 99.99% as a target material and ITO conductive glass as a conductive substrate, direct current reactive deposition sputtering is performed on the ITO conductive glass. The direct current reactive deposition sputtering is performed in a chamber with a vacuum degree of less than 6×10 ^-4 Pa, using an oxygen-argon mixed atmosphere, with an argon gas flow rate of 30 sccm, an oxygen gas flow rate of 10 sccm, a sputtering power of 100 W, a sputtering pressure of 0.3 Pa, a sputtering time of 18 min, and a working distance of 10 cm to obtain a tungsten trioxide intermediate layer.

S2. Using _TiO2 with a purity of more than 99.99% as the target material, radio frequency deposition sputtering is performed on the tungsten trioxide intermediate layer. The protective atmosphere of the radio frequency deposition sputtering is argon, the gas flow rate of argon is 20sccm, the sputtering power is 100W, the sputtering pressure is 0.2Pa, the sputtering time is 10min, and the working distance is 10cm to obtain a titanium dioxide surface layer.

The ITO conductive glass was ultrasonically cleaned in acetone, ethanol and deionized water for 10 min in sequence before use, and then dried in a vacuum oven for later use.

The difference between the preparation method of this comparative example and that of Example 1 is that no metal tungsten bottom layer is prepared.

It was detected that the thin film material prepared in this comparative example had a layered characteristic, and the thickness of the tungsten trioxide middle layer was 180 nm, and the thickness of the titanium dioxide surface layer was 10 nm.

As shown in (a) to (f) in Figure 14, in the figure, the lower half of the transparent substrate is provided with the thin film material of this comparative example. The thin film material prepared in this comparative example appears to be transparent in appearance when there is no voltage, and has a high transmittance in the entire visible light spectrum range, and the thin film material has almost no perceptible structural color. Using the constant potential polarization method, a voltage of 0 to -0.5V is applied to the prepared thin film material samples, and the thin film material only changes from a colorless and transparent state to blue and the blue gradually deepens. That is: only the depth change of a single color can be achieved, and the change of multiple colors cannot be achieved, and the distinction is not high. When applied to energy storage devices, only changes in color depth and transparency can occur. The color richness and distinction are obviously not as good as the technical effects of Example 1.

Through the above embodiments and comparative examples, it can be seen that: in the technical scheme of the present invention, the thickness of the tungsten bottom layer and the titanium dioxide surface layer can affect the performance of the electrochromic/capacitive dual-function thin film material: if there is no tungsten bottom layer, the electrochromic color can only achieve changes in color depth, and the color of the thin film material can only achieve a transition between colorless and blue; and if there is no titanium dioxide surface layer, the coloring efficiency of the thin film material is low and the capacitance rate performance is poor. The technical scheme of Example 1 can be used to obtain the best technical effect.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. An electrochromic/capacitive dual-function film material comprising: a titanium dioxide surface layer with the thickness of 5-40 nm, a tungsten trioxide middle layer with the thickness of 150-210 nm and a metal tungsten bottom layer with the thickness of 20-40 nm; and metallic tungsten, tungsten trioxide and titanium dioxide are all amorphous.

2. The electrochromic/capacitive dual function film material of claim 1, wherein the metallic tungsten underlayer is on a conductive substrate, the conductive substrate being ITO conductive glass.

3. A method for preparing an electrochromic/capacitive dual-function film material according to any one of claims 1-2, comprising the steps of:

S1, performing direct current deposition sputtering on the surface of a conductive substrate by taking metal tungsten as a target material to obtain a metal tungsten bottom layer with a set thickness;

S2, performing direct current reaction deposition sputtering on the surface of a metal tungsten bottom layer in an oxygen-containing atmosphere by taking the metal tungsten as a target material to obtain a tungsten trioxide middle layer with a set thickness;

S3, performing radio frequency deposition sputtering on the surface of the tungsten trioxide intermediate layer by taking titanium dioxide as a target material to obtain a titanium dioxide surface layer with a set thickness.

4. The method for preparing the electrochromic/capacitive dual-function film material according to claim 3, wherein in the step S1, W with the purity of more than 99.99% is used as a target; DC deposition sputtering was performed in an argon atmosphere in a chamber having a vacuum degree of 6X 10 ^-4 Pa or less.

5. The method of manufacturing an electrochromic/capacitive dual-function thin film material according to claim 4, wherein in S1, the flow rate of argon gas is 15-25 sccm, the sputtering power is 80-120W, the sputtering air pressure is 0.2-0.25 Pa, the sputtering time is 3-5 min, and the working distance is 10-12 cm during the direct current deposition sputtering process.

6. The method for preparing the electrochromic/capacitive dual-function film material according to claim 3, wherein in the step S2, W with the purity of more than 99.99% is used as a target; in a chamber having a vacuum degree of 6×10 ^-4 Pa or less, a volume ratio of oxygen to argon is 1: and (2.5-3) performing direct current reactive deposition sputtering in a mixed atmosphere.

7. The method of manufacturing an electrochromic/capacitive dual-function thin film material according to claim 6, wherein in S2, the flow rate of argon gas is 25-30 sccm, the flow rate of oxygen gas is 10-12 sccm, the sputtering power is 80-120W, the sputtering air pressure is 0.3-0.35 Pa, the sputtering time is 15-18 min, and the working distance is 10-12 cm during the direct-current reactive deposition sputtering.

8. The method for preparing an electrochromic/capacitive dual-function thin film material according to claim 3, wherein in S3, tiO2 with a purity of 99.99% or more is used as a target material, and radio-frequency deposition sputtering is performed in an argon atmosphere in a chamber with a vacuum degree of 6 x 10 ^-4 Pa or less.

9. The method for preparing an electrochromic/capacitive dual-function thin film material according to claim 8, wherein in the step S3, the gas flow of argon is 15-25 sccm, the sputtering power is 80-120W, the sputtering air pressure is 0.2-0.25 Pa, the sputtering time is 8-10 min, and the working distance is 10-12 cm.

10. Use of an electrochromic/capacitive difunctional film material according to any one of claims 1 to 2, characterized in that said use comprises: the application in the color-changing energy storage device.