CN117777992A - Preparation method of electrochromic material and electrochromic device - Google Patents

Abstract

The invention discloses a preparation method of electrochromic materials and electrochromic devices. The steps of the preparation method include: a) dropping a metal salt solution into a V ₂ O ₅ sol, and stirring to obtain a V ₂ O ₅ based mixed sol; The metal includes at least one of Zn, Al, Fe or Cr; b) Coating the V ₂ O ₅ -based mixed sol on the substrate to form a film to obtain an electrochromic layer material; the V ₂ obtained by the preparation method The O5 _- based electrochromic layer material has rich color change types, good stability, simple preparation process, low processing cost, and wide application fields.

Description

Preparation method of electrochromic material, electrochromic device

Technical field

The present invention relates to the technical field of electrochromic materials, specifically to a preparation method of electrochromic materials and electrochromic devices.

Background technique

Electrochromism is a phenomenon in which a material undergoes a stable and reversible color change (reflectivity, transmittance, absorptivity, etc.) under the action of an external electric field, which is manifested in a reversible change in color and transparency. Due to the advantages of low energy consumption, low driving voltage, the ability to maintain the display state when there is no voltage, and rich colors, electrochromic devices have very good application prospects in the fields of smart windows, car rearview mirrors, and displays. The light modulation of electrochromic devices plays a very important role in building energy conservation. For example, in summer, the absorption of infrared rays by smart windows can be changed to reduce the increase in indoor temperature. For example, the portholes of the Boeing 787 use an all-in-one electrochromic device structure. The electrochromic materials of the all-in-one electrochromic device are mainly compounds of the violaceous and tungsten oxide systems. The above applications are all transmissive electrochromic devices.

Vanadium oxide is widely used in electrochromic materials. In the past 10 to 20 years, the sol-gel method for synthesizing vanadium oxide materials has also been studied and developed. However, the layered structure of vanadium oxide itself is unstable, and it is very easy to cause the collapse of the ion diffusion channel structure during the ion insertion and extraction process. At the same time, the color change range _of a single _V2O5 dry gel under the action of an external electric field is relatively narrow.

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 regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

Summary of the invention

The present invention provides a preparation method of electrochromic materials and an electrochromic device, which are used to overcome the above technical problem of maintaining a narrow color range in the prior art.

The first object of the present invention is to provide a method for preparing electrochromic materials. The steps include:

a) Add the metal salt solution dropwise into the V ₂ O ₅ sol and stir to obtain a V ₂ O ₅ based mixed sol; the metal includes at least one of Zn, Al, Fe or Cr;

b) Coat the V ₂ O ₅ -based precursor on the substrate to obtain the electrochromic layer material after film formation.

Further, in the V ₂ O ₅ -based mixed sol, the molar ratio of vanadium element to metal element is (5-100):1.

Furthermore, the metal salt is a nitrate or a chloride.

Furthermore, the V ₂ O ₅ sol is prepared by dispersing V ₂ O ₅ powder in an aqueous solution containing hydrogen peroxide.

Preferably, the solid-liquid ratio of the V ₂ O ₅ powder and the hydrogen peroxide-containing aqueous solution is 0.1 to 100 g: 10 to 1000 mL; and/or the mass ratio of the water to hydrogen peroxide is (5 to 20): 1. The content of hydrogen peroxide is 8 to 30%.

Further, the coating refers to forming a thin film on the surface of the conductive substrate with a V ₂ O ₅ -based mixed sol, and the coating is selected from one of electrodeposition plating, spin coating, dip-drawing or spray coating.

Preferably, the coating adopts electrodeposition coating, and is annealed in an oxygen-rich atmosphere after coating; and/or the substrate is a conductive substrate, preferably ITO glass.

Preferably, the temperature of the annealing treatment is 100 to 290°C, and the holding time is 1 to 15 hours; and/or the temperature rise rate of the annealing treatment is 0.5 to 10°C/min. The annealing treatment is beneficial to the internal stress release of the polymer in the V ₂ O ₅ xerogel-based electrochromic material and the morphology is stretched.

Furthermore, in step a), the temperature of the solution during dropwise addition is 15-40° C.; and/or the dropwise addition time is less than 10 s. Step a) also includes the steps of filtering and washing the V ₂ O ₅ -based mixed sol.

The second object of the present invention is to provide an electrochromic device, comprising the electrochromic material obtained by the preparation method described in the first object above.

Compared with the prior art, the present invention has the following beneficial effects:

1. The preparation method provided by the present invention modifies _V2O5 by metal salt to obtain a sol-gel type electrochromic material, which can change _the voltage to achieve reversible changes in multiple colors, and the color change types are rich. When used as a coating material with camouflage function, it has a wider range of active adaptability, which is more conducive to realizing the camouflage and stealth functions of combat equipment such as aircraft and armored vehicles in special _environments ; in addition, the _V2O5 dry gel-based electrochromic material prepared by this method is an inorganic reflective electrochromic material with good mobility, and can achieve functional upgrades of adaptive camouflage in different scenarios through spraying, printing, pasting and other methods, which greatly broadens the application scenarios of electrochromic materials and has broad application prospects.

2. The electrochromic material obtained by the preparation method of the present invention is used to prepare electrochromic devices. It not only has a simple preparation process and low processing cost, but also can realize more types of color changes at a smaller voltage. Application The field is wide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an X-ray diffraction (XRD) diagram of the electrochromic material powder obtained in Examples 1-5 of the present invention.

Figure 2 is a diagram showing the discoloration effects of the electrochromic film modified by a single metal under different voltages according to the embodiment of the present invention.

Figure 3 is a diagram showing the discoloration effect of the electrochromic film obtained by multi-metal modification under different voltages according to the embodiment of the present invention.

Figure 4 is a comparison result of the color reversal rate of electrochromic films modified with different metals according to the embodiment of the present invention.

Figure 5 is a CV curve of an electrochromic material modified with different metals in an embodiment of the present invention.

Figure 6 is a scanning electron microscope image of an electrochromic material modified by a single metal in an embodiment of the present invention.

Figure 7 is a scanning electron microscope image and an EDS scanning image of an electrochromic material modified with multiple metals in an embodiment of the present invention.

Detailed ways

The technical solution of the present invention will be clearly and completely described below in conjunction with the preferred embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In one embodiment, a method for preparing electrochromic materials is proposed, including the following steps:

a) Add the metal salt solution dropwise into the V ₂ O ₅ sol and stir to obtain a V ₂ O ₅ based mixed sol; the metal includes at least one of Zn, Al, Fe or Cr;

b) Electrodeposit the V ₂ O _5- based mixed sol onto the conductive substrate;

c) annealing the coated substrate in an oxygen-rich atmosphere to obtain an electrochromic layer material.

In the above embodiment, _metal ions can be inserted into the interlayer of the crystalline structure of _V2O5 during the process of vanadium pentoxide forming a sol-gel, replacing the H ions in _the structure to form _{H1- xMxV6O16.5} (M _is Zn, Al, Fe or Cr), thereby improving the electrochromic performance of the _{V2O5 -} based electrochromic material during the electrochromic process. Frequent diffusion can cause irreversible damage to the electrochromic film due to the instability of the interlayer structure during the insertion and extraction of ions and electrons. The addition of metals can enhance the electrochromic performance of the film.

In the above embodiments, the preparation method uses a metal salt to modify V ₂ O ₅ to obtain a sol-gel electrochromic material, which can achieve reversible changes in multiple colors by changing the voltage. The types of color changes are rich, and it has a camouflage function. When used as a coating material, it has wider active adaptability and is more conducive to realizing the camouflage and stealth function of aircraft, armored vehicles and other combat equipment in special environments; the electrochromic material obtained by the preparation method is an inorganic reflective electrochromic The material has good migration properties and can achieve adaptive camouflage function upgrades in different scenarios through spraying, printing, pasting and other methods, which greatly broadens the application scenarios of electrochromic materials.

In some embodiments, the _{V2O5 -} based mixed sol can be prepared not only by electrochemical deposition to prepare a color-changing coating, but also by spin coating, dip-pull or spray coating to obtain a color-changing thin film material according to the viscosity of the sol, which greatly develops the application range of vanadium pentoxide-based electrochromic materials.

In a preferred embodiment, the added metal salt is suitable for modifying the vanadium pentoxide electrochromic material, thereby obtaining a V ₂ O ₅ -based electrochromic film with excellent performance. Because metal ions in the sol can improve the conductivity of V ₂ O ₅ -based electrochromic materials, this special structural state ensures a stable channel for ions. The metal ions inserted between the V ₂ O ₂ layers play the role of expanding the layer spacing and "supporting body" to reduce the electrochemical reaction energy barrier, which is beneficial to improving the material's cycle performance and reflection range. Further, according to some specific examples of the present invention, the molar ratio of vanadium element and metal element in the vanadium pentoxide sol can be (5-100):1, for example, it can be 5/1, 10/1, 20/1 , 50/1 or 100/1, etc., thus, it is more conducive to take into account the yellow-green color change range of V ₂ O ₅ -based electrochromic materials, the speed of color change under small voltage, cycle stability and reflectivity control ability . It should be noted that there is no particular restriction on the specific type of metal salt solution. Those skilled in the art can flexibly choose according to the actual situation, as long as the free movement of metal ions in the salt solution can be achieved. For example, the metal salt can be selected from nitrates. One or more of its hydrates, chlorides and their hydrates, such as at least one of zinc nitrate, aluminum nitrate, ferric nitrate and chromium nitrate, and/or, zinc chloride, aluminum chloride, At least one of ferric chloride and chromium chloride; or adding metal oxides to form metal ions through dissolution treatment may include at least one of Zn, Al, Fe and Cr.

In a preferred embodiment, the vanadium pentoxide powder is mixed with water and hydrogen peroxide solvent, so that the vanadium pentoxide is dispersed and dissolved in the solvent, so as to obtain a uniform and stable vanadium pentoxide sol for subsequent steps. Electrochemical deposition processes and annealing processes provide the basis. Wherein, the solid-liquid ratio of vanadium pentoxide powder and solvent can be (0.1~100)g/(10~1000)mL, for example, it can be 0.1g/1000mL, 0.5g/1000mL, 1g/1000mL, 2g/1000mL, 3g/100mL, 10g/100mL, 50g/1000mL, 100g/1000mL, 2g/10mL, 5g/10mL, 20g/1000mL, 40g/10mL, 60g/1000mL, 80g/1000mL, 10g/900mL, 10g/700mL, 10g/ 500mL or (0.5~90)g/(15~800)mL, etc., which is beneficial to control the reaction speed and sol concentration in the subsequent dissolution process, thereby enhancing the degree of modification of V ₂ O ₅ by metal ions in the sol. . In addition, this embodiment has no special restrictions on the purity of vanadium pentoxide. Those skilled in the art can flexibly select according to actual conditions. For example, at least one of 95.0%, 99.0%, 99.5%, 99.9% and 99.99% can be selected.

In a preferred embodiment, the temperature of the stirring and mixing treatment in step a) can be room temperature, slightly above or slightly below room temperature, for example, 40°C, 30°C, 25°C, 15°C or 20°C, and the mixing treatment time should be fast, which can be 0.1s to 10s, for example, 0.1s, 1s, 3s, 5s, 8s or 10s, etc., thereby not only avoiding the hydrolysis reaction of the metal salt solution in water, but also quickly modifying the _vanadium oxide, which is beneficial to the subsequent interlayer modification of the _V2O5 matrix in the electrochemical deposition process, thereby making the modified vanadium pentoxide-based electrochromic material have better color change performance and cycle stability.

In a preferred embodiment, the voltage applied to the working electrode (conductive ITO glass) during the electrodeposition process can be -0.8V to -1.0V, for example, -0.8V, -0.85V, -0.9V or -1.0V, and the pressurization time is 10 to 15s. The electrochemical method not only ensures that the vanadium pentoxide sol is modified by metal ions during deposition, but also makes the deposited film more uniform, thereby ensuring the uniformity of the electrochromic properties of the film after annealing during the voltage application process.

In a preferred embodiment, the temperature rise rate during the annealing process can be 0.5°C/min to 10°C/min, for example, it can be 0.5°C/min, 1°C/min, 3°C/min, 5°C/min or 10°C /min, etc. This approach can not only ensure the loss of the tube furnace during the heating process, save time during the processing, but also avoid damage to the V ₂ O ₅ -based electrochromic film due to excessive temperature rise during the annealing process. of destruction. In addition, the annealing process needs to be carried out in an oxygen-rich atmosphere.

In a preferred embodiment, 0.1g to 100g of vanadium pentoxide powder can be mixed with a solvent of 10mL to 1000mL of water and hydrogen peroxide to obtain a uniform vanadium pentoxide sol; the obtained sol is mixed with a metal salt The solution reacts fully at room temperature, and then the reaction product is cleaned and separated by centrifugation, suction filtration, etc., to obtain a V ₂ O ₅ -based precursor mixed sol; then the precursor is electrochemically deposited to obtain an electrochromic material, 0.5°C/ Min～10℃/min heating rate, heat up to 100℃～290℃ and keep it for 1h～15h, to obtain a V ₂ O ₅ -based electrochromic film. The electrochromic film can be used at a smaller voltage (such as not more than 1.6V ), reversible changes in yellow, orange, blue, green and other colors can be achieved by changing the voltage value.

The following are examples of preferred implementation methods for the preparation method of reflective biomimetic electrochromic layer materials. Except for the methods specifically defined in the text, the methods involved in the process are those mastered by those in the field, and the reagents used are all commercially available standard products.

Materials: Hydrogen peroxide, content 30%; vanadium pentoxide, zinc nitrate, aluminum nitrate, iron nitrate, chromium nitrate, purity greater than 99%.

Example 1

(1) Add 1.5g V ₂ O ₅ powder to 100 mL of a mixed solution of water and hydrogen peroxide with a mass ratio of 10:1, stir for 10 hours at room temperature of 25°C, and fully dissolve to obtain V ₂ O ₅ sol. Rest for 5 days;

(2) Dissolve 0.5g of zinc nitrate (Zn(NO ₃ ) ₂ ) into 10 mL of water, then quickly drop the solution into the V ₂ O ₅ sol obtained in step (1), stir at room temperature for 5 hours, and stir thoroughly. The reaction yields a V ₂ O _5- based mixed sol;

(3) The ITO glass is placed in a beaker of an ultrasonic cleaner for cleaning. It is first cleaned with a saturated sodium hydroxide solution, and then the cleaning solution in the beaker is replaced with anhydrous ethanol. Finally, it is cleaned with deionized water. The cleaning time in each cleaning agent is 15 minutes. After cleaning, it is dried in an oven for later use.

(4) Use the V ₂ O ₅ mixed sol in step (2) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and -0.9V is applied to the working electrode. Apply voltage for 15 seconds and take out the electrodeposited ITO conductive glass;

(5) Place the ITO glass on which the mixed sol is deposited in step (4) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 150°C, the heating rate is 5°C/min, the annealing time is 7 hours, and the temperature is lowered. At a rate of 10°C/min, a reflective Zn/V ₂ O _5- based electrochromic thin film material was obtained.

Example 2

(1) Add 1.5g of vanadium pentoxide powder to 100 mL of a mixed solution of water and hydrogen peroxide with a mass ratio of 10:1, stir for 10 hours at room temperature of 25°C, and fully dissolve to obtain a vanadium pentoxide sol. Rest for 5 days;

(2) Dissolve 0.3g aluminum nitrate (Al(NO ₃ ) ₃ ) into 10 mL of water, then quickly drop the solution into the V ₂ O ₅ sol obtained in step (1), and stir at room temperature for 5 hours. The reaction yields a V ₂ O _5- based mixed sol;

(3) Place the ITO glass in the beaker of the ultrasonic cleaner for cleaning, first clean it with saturated sodium hydroxide solution, then change the cleaning liquid in the beaker to absolute ethanol, and finally clean it with deionized water. The cleaning time in the first cleaning agent is 15 minutes. After the cleaning is completed, dry it in the oven for later use;

(4) using the V ₂ O ₅ mixed sol in step (2) to perform electrodeposition coating, using a three-electrode system, wherein the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, a voltage of -0.9 V is applied to the working electrode for 15 s, and the ITO conductive glass after electrodeposition is taken out;

(5) Place the ITO glass on which the mixed sol is deposited in step (4) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 180°C, the heating rate is 5°C/min, the annealing time is 9 hours, and the temperature is lowered. At a rate of 10°C/min, a reflective Al/V ₂ O _5- based electrochromic thin film material was obtained.

Example 3

(1) Add 1.5g V ₂ O ₅ powder to 100 mL of a mixed solution of water and hydrogen peroxide with a mass ratio of 10:1, stir for 10 hours at room temperature of 25°C, and fully dissolve to obtain V ₂ O ₅ sol. Rest for 5 days;

(2) Dissolve 0.1g iron nitrate (Fe(NO ₃ ) ₃ ) into 10 mL of water, then quickly drop the solution into the V ₂ O ₅ sol obtained in step (1), and stir at room temperature for 5 hours. The reaction yields a V ₂ O _5- based mixed sol;

(3) Place the ITO glass in the beaker of the ultrasonic cleaner for cleaning, first clean it with saturated sodium hydroxide solution, then change the cleaning liquid in the beaker to absolute ethanol, and finally clean it with deionized water. The cleaning time in the first cleaning agent is 15 minutes. After the cleaning is completed, dry it in the oven for later use;

(4) Use the V ₂ O ₅ mixed sol in step (2) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and -0.9V is applied to the working electrode. Apply voltage for 15 seconds and take out the electrodeposited ITO conductive glass;

(5) Place the ITO glass on which the mixed sol was deposited in step (4) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 220°C, the heating rate is 5°C/min, the annealing time is 12h, and the temperature is lowered. At a rate of 10°C/min, a reflective Fe/V ₂ O _5- based electrochromic thin film material was obtained.

Example 4

(1) 1.5 g of V ₂ O ₅ powder was added to 100 mL of a mixed solution of water and hydrogen peroxide in a mass ratio of 10:1, and stirred at room temperature of 25°C for 10 h to fully dissolve to obtain a V ₂ O ₅ sol, which was then left to stand for 5 days;

(2) Dissolve 0.5g chromium nitrate (Cr(NO ₃ ) ₃ ) into 10 mL of water, then quickly drop the solution into the V ₂ O ₅ sol obtained in step (1), and stir at room temperature for 5 hours. The reaction yields a V ₂ O _5- based mixed sol;

(3) Place the ITO glass in the beaker of the ultrasonic cleaner for cleaning, first clean it with saturated sodium hydroxide solution, then change the cleaning liquid in the beaker to absolute ethanol, and finally clean it with deionized water. The cleaning time in the first cleaning agent is 15 minutes. After the cleaning is completed, dry it in the oven for later use;

(4) Use the V ₂ O ₅ mixed sol in step (2) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and -0.9V is applied to the working electrode. Apply voltage for 15 seconds and take out the electrodeposited ITO conductive glass;

(5) placing the ITO glass on which the mixed sol is deposited in step (4) in a tube furnace and annealing the glass in an oxygen-rich atmosphere at a temperature of 290° C., a heating rate of 5° C./min, an annealing time of 14 h, and a cooling rate of 10° C./min to obtain a reflective Cr/V ₂ O ₅ -based electrochromic thin film material.

Example 5

(1) Add 1.0g V ₂ O ₅ powder to 100 mL of a mixed solution of water and hydrogen peroxide with a mass ratio of 5:1, stir for 10 hours at room temperature of 25°C, and fully dissolve to obtain V ₂ O ₅ sol. Rest for 5 days;

(2) dissolving 0.2 g of chromium nitrate (Cr(NO ₃ ) ₃ ) and 0.2 g of ferric nitrate (Fe(NO ₃ ) ₃ ) in 15 mL of water, and then rapidly dropping the solution into the V ₂ O ₅ sol obtained in step (1), stirring at room temperature for 5 h, and fully reacting to obtain a V ₂ O ₅ -based mixed sol;

(3) Place the ITO glass in the beaker of the ultrasonic cleaner for cleaning, first clean it with saturated sodium hydroxide solution, then change the cleaning liquid in the beaker to absolute ethanol, and finally clean it with deionized water. The cleaning time in the first cleaning agent is 15 minutes. After the cleaning is completed, dry it in the oven for later use;

(4) Use the V ₂ O ₅ mixed sol in step (2) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and -1.0V is applied to the working electrode. Apply voltage for 20 seconds and take out the electrodeposited ITO conductive glass;

(5) Place the ITO glass on which the mixed sol was deposited in step (4) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 260°C, the heating rate is 5°C/min, the annealing time is 14h, and the temperature is lowered. At a rate of 10°C/min, a composite V ₂ O _5- based electrochromic thin film material was obtained.

Example 6

(1) Add 1.0g of vanadium pentoxide powder to 100 mL of a mixed solution of water and hydrogen peroxide with a mass ratio of 10:1, stir for 10 hours at room temperature of 25°C, and fully dissolve to obtain a vanadium pentoxide sol. Rest for 5 days;

(2) Dissolve 0.2 g aluminum nitrate (Al(NO ₃ ) ₃ ) and 0.2 g zinc nitrate (Zn(NO ₃ ) ₂ ) in 10 mL of water, then quickly drop the solution into the V ₂ O ₅ sol obtained in step (1), stir at room temperature for 5 h, and react fully to obtain a V ₂ O ₅ -based mixed sol;

(3) The ITO glass is placed in a beaker of an ultrasonic cleaner for cleaning. It is first cleaned with a saturated sodium hydroxide solution, and then the cleaning solution in the beaker is replaced with anhydrous ethanol. Finally, it is cleaned with deionized water. The cleaning time in each cleaning agent is 15 minutes. After cleaning, it is dried in an oven for later use.

(4) Use the vanadium pentoxide mixed sol in step (2) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and -1.2V is applied to the working electrode. Apply voltage for 20 seconds and take out the electrodeposited ITO conductive glass;

(5) Place the ITO glass on which the mixed sol is deposited in step (4) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 290°C, the heating rate is 5°C/min, the annealing time is 14h, and the temperature is lowered. At a rate of 10°C/min, a composite V ₂ O _5- based electrochromic thin film material was obtained.

Comparative Example

(1) Add 2.0 g of V ₂ O ₅ powder to 100 mL of a mixed solution of water and hydrogen peroxide in a mass ratio of 5:1, stir for 10 h at room temperature (25 °C) to fully dissolve to obtain a V ₂ O ₅ sol, and let it stand for 5 days;

(2) Place the ITO glass in the beaker of the ultrasonic cleaner for cleaning, first clean it with saturated sodium hydroxide solution, then change the cleaning liquid in the beaker to absolute ethanol, and finally clean it with deionized water. The cleaning time in the first cleaning agent is 15 minutes. After the cleaning is completed, dry it in the oven for later use;

(3) Use the V ₂ O ₅ sol in step (1) for electrodeposition coating, using a three-electrode system, in which the counter electrode is a platinum electrode, the reference electrode is a calomel electrode, and a voltage of -1V is applied to the working electrode for 15 seconds. , take out the ITO conductive glass after electrodeposition;

(4) Place the ITO glass on which V ₂ O ₅ was deposited in step (3) in a tube furnace and perform annealing treatment in an oxygen-rich atmosphere. The annealing temperature is 100°C, the heating rate is 5°C/min, and the annealing time is 5 hours. , with a cooling rate of 10°C/min, a reflective V ₂ O ₅ electrochromic thin film material was obtained.

Experiments and Analysis

1. X-ray diffraction (XRD) analysis

The annealed V ₂ O _5- based electrochromic film prepared in the above-mentioned embodiment and comparative example is peeled off the ITO conductive glass, and the powder obtained after drying is characterized by X-ray diffraction (XRD). As shown in Figure 1, it can be seen from the XRD spectrum that the formation of the new phase is positively correlated with the type of different types of metal elements. The comparative example is an unmodified vanadium pentoxide sol, and the formation of the new phase cannot be seen. With the modification of different metals, different types of modified substances are formed in the sol, and with the growth of the nucleus, the appearance of the (002) crystal plane belongs to the typical monoclinic phase H _1-x M _x V ₆ O _16.5 (M is Zn, Al, Fe and Cr) diffraction peak. The half-peak width in the XRD spectrum gradually decreases, the diffraction peak becomes more and more sharp, and the diffraction peak intensity increases, indicating that the crystallinity of the vanadium oxide material gradually increases, the grain growth becomes larger, and the H _1-x M _x V ₆ O _16.5 phase structure is gradually improved.

2. Color change test

1) Test the change in optical color of the V ₂ O _5- based electrochromic film modified by a single metal element from -1V to 1V and in the initial state. In Examples 1-4, the films were modified with Zn, Al, Fe, and Cr elements respectively. The color change of the V ₂ O _5- based electrochromic film is shown in Figure 2. When the voltage is changed from negative to positive, the V ₂ O _5- based electrochromic film can produce a color change between blue-green and orange-red. Taking Cr element modification as an example, the film appears blue-green at -1V, green at -0.4V, yellow at +0.6V, and orange-red at 1.0V. Effect.

2) Test the change in optical color of the V ₂ O _5- based electrochromic film modified with multi-metal elements from -1V to 1V and in the initial state. The color changes of the V ₂ O ₅ -based electrochromic films modified with Cr and Fe elements in Example 5, and Al and Zn elements modified in Example 6 are shown in Figure 3. Figure 3 shows the color change after modification of vanadium pentoxide by two different metal elements and provides a detailed color display at a voltage of ±1V. By modifying multivalent V ions, it is easy to superpose and synergize the valence changes in the electrochromic process, so that the V ₂ O ₅ xerogel-based electrochromic material can operate at a smaller voltage (such as no more than 1.6V). ), reversible changes in multiple colors can be achieved by changing the voltage, and the types of color changes are rich.

3. Reflectivity test

The modified _{V2O5 -} based electrochromic film obtained in the above embodiment was tested for reflectivity, and the test results are shown in Figure 4. When the modified metal element is Zn, the maximum optical anti-color rate value of the film in the range of ultraviolet-visible light is 29.4%, and when the modified metal element is Al, it is 31.3%; when Cr and Fe are modified together, the reflective modulation of the film is 42.4%. After the vanadium pentoxide-based electrochromic material is modified by Cr element, the reflective modulation rate is the largest, reaching 48.4%, indicating that there are differences in anti-color rates between electrochromic films modified by different metal elements.

4.CV curve test

The CV curve test was performed on the V ₂ O _5- based electrochromic material modified in the above examples. The working environment of the test was a three-electrode system. The reference electrode and counter electrode were exactly the same as during electrodeposition. The electrolyte was LiClO ₄ /PC. solution. The test results of Al/V ₂ O ₅ , Cr/V ₂ O ₅ , Al and Zn composite modified V ₂ O ₅ based electrochromic materials are shown in Figures 5a, 5b and 5c.

When H _{1 - x M} V ⁵⁺ ) and the tetravalent state (V ⁴⁺ ). It shows that the modified V ₂ O ₅ -based film provides excellent cycle stability and charge capacitance, which is related to the ability of metal elements to directly increase the interlayer spacing. Under the same electrochemical deposition preparation process, the higher the annealing temperature, the higher the physical phase. The more stable the structure, the more lithium ions it can hold. The addition of metal elements changes the original lattice structure, provides a transmission channel for lithium ions, and has a greater impact on conductivity.

5. Microstructural characterization

1) The microstructure of the modified film of Example 1-4 was obtained by scanning electron microscopy as shown in Figure 6. The image accurately and clearly proves the granular morphology of the _{V2O5 -} based electrochromic material after metal element modification. This cross-linked network is conducive to the firm attachment of the film to the ITO conductive glass, improving the durability of the film. At the same time, this special structural state ensures the stable passage of ions and improves the electrochromic performance.

2) The distribution of V, O, Cr and Fe elements in the composite film obtained in Example 5 was analyzed by scanning electron microscopy. As shown in Figure 7, it was found that the elements were evenly distributed. EDS scanning was performed on the scanning electron microscope to obtain the element distribution image. The mass percentages of V, O, Cr and Fe elements were 35.5%, 45.6%, 9.4% and 9.5%, respectively. This shows that the metal ions were successfully embedded in _{the V2O5} interlayer, playing the role of expanding the interlayer spacing and "support".

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. The preparation method of electrochromic material, characterized in that the steps include: a) Add the metal salt solution dropwise into the V ₂ O ₅ sol and stir to obtain a V ₂ O ₅ based mixed sol; the metal includes at least one of Zn, Al, Fe or Cr; b) coating the V ₂ O ₅ -based mixed sol on a substrate to obtain an electrochromic material after film formation. 2. The preparation method according to claim 1, characterized in that when the dropwise addition is completed, the molar ratio of vanadium element to metal element in the V ₂ O ₅ sol is (5-100):1. 3. The preparation method according to claim 1, characterized in that the metal salt is nitrate or chloride salt. 4. The preparation method according to claim 1, characterized in that the V ₂ O ₅ sol is prepared by dispersing V ₂ O ₅ powder in an aqueous solution containing hydrogen peroxide. 5. The preparation method according to claim 4, characterized in that the solid-liquid ratio of the V ₂ O ₅ powder and the hydrogen peroxide-containing aqueous solution is 0.1 to 100 g: 10 to 1000 mL; and/or, the water and The mass ratio of hydrogen peroxide is (5-20):1, and the content of hydrogen peroxide is 8-30%. 6. The preparation method according to claim 1, characterized in that the coating is selected from one of electrodeposition plating, spin coating, dip coating or spray coating. 7. The preparation method according to claim 6, wherein the coating adopts electrodeposition coating, and is annealed in an oxygen-rich atmosphere after coating; and/or the base material is a conductive base material. 8. The preparation method according to claim 7, characterized in that the temperature of the annealing treatment is 100-290°C, and the holding time is 1-15h; And/or, the temperature rise rate of the annealing treatment is 0.5-10°C/min. 9. The preparation method according to claim 1, characterized in that in step a), the temperature when the solution is added dropwise is 15-40°C; And/or, the solution is added dropwise for less than 10 seconds; And/or, step a) also includes the steps of suction filtration and cleaning of the V ₂ O ₅ -based mixed sol. 10. Electrochromic device, characterized by comprising the electrochromic material obtained by the preparation method according to any one of claims 1-9.