CN116184733A - Potassium ion doped V 2 O 5 Electrochromic film and preparation method and application thereof - Google Patents

Abstract

The invention discloses a potassium ion doped V ₂ O ₅ An electrochromic film, a preparation method and application thereof, comprising the following steps: will V ₂ O ₅ Dissolving the powder in water, uniformly mixing, adding a potassium chloride solution into the mixture to obtain a mixed solution, wherein the concentration of the potassium chloride is 1-3mol/L, and stirring to obtain colloid; washing the colloid with water, centrifuging, and removing excessive potassium chloride; carrying out ultrasonic dilution on the washed colloid by adopting distilled water; adding cellulose into the diluted colloid; heating and stirring to obtain a KVO paste; the KVO paste is coated on a conductive substrate by a clean glass rod, and after the adhesive tape is torn off, cellulose is removed by heat curingObtaining the KVO electrochromic film. In V by simple solution method ₂ O ₅ The V is widened by doping potassium element ₂ O ₅ The color control range of the cathode is formed by a bar coating method in one step, and electrochromic V can be realized by taking metallic zinc as an anode ₂ O ₅ Self-coloring process of the film.

Description

Potassium ion doped V 2 O 5 Electrochromic film and preparation method and application thereof

Technical Field

The invention belongs to the technical field of electrochromic films, and particularly relates to a potassium ion doped V ₂ O ₅ Electrochromic film and preparation method and application thereof.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

The vanadium element has various oxidation states (V ²⁺ 、V ³⁺ 、V ⁴⁺ And V ⁵⁺ ) Can enable the presence of a plurality of vanadium oxides, wherein V ₂ O ₅ Is thermodynamically most stable and exhibits excellent optical and electrochemical properties. Under the action of an externally applied electric field, V ₂ O ₅ The transition of electrons and the change of valence state of vanadium element can be generated, and the change of color and transparency can be expressed in a reversible way in appearance. V (V) ₂ O ₅ The electrochromic phenomenon of the glass has good application prospect in a plurality of fields, and the main application directions at present are electrochromic intelligent windows, electrochromic supercapacitors, non-active luminous flat panel displays, intelligent anti-dazzle rearview mirrors and the like.

However, the original V ₂ O ₅ The problems are that the color change is single, the film forming method is complex and has high cost, and the structure is collapsed due to repeated deintercalation of ions in the electrochromic process, so that the service life of the device is shortened. Therefore, researches of researchers are focused on increasing the color control range and prolonging the service life by adjusting the synthetic environment, doping elements, composite materials and the like.

However, at present V ₂ O ₅ The film forming method such as a hydrothermal method, a magnetron sputtering method, a chemical vapor deposition method and the like often needs expensive equipment and has strict requirements on preparation conditions. It is particularly important that these methods are not suitable for large area low cost applications.

Disclosure of Invention

Against the prior art there isThe invention aims to provide a V doped with potassium ions ₂ O ₅ Electrochromic film and preparation method and application thereof. In V by simple solution method ₂ O ₅ The V is widened by doping potassium element ₂ O ₅ The color control range of the cathode is formed by a bar coating method in one step, and electrochromic V can be realized by taking metallic zinc as an anode ₂ O ₅ The self-coloring process of the film greatly reduces the energy consumption. The preparation method of the film is simple, low in cost and environment-friendly.

In order to achieve the above object, the present invention is realized by the following technical scheme:

in a first aspect, the present invention provides a potassium ion doped V ₂ O ₅ The preparation method of the electrochromic film comprises the following steps:

will V ₂ O ₅ Dissolving the powder in water, mixing, adding potassium chloride solution to obtain mixed solution, and adding V ₂ O ₅ The concentration of potassium chloride is 50-80g/L, the concentration of potassium chloride is 1-3mol/L, and the colloid is obtained by stirring;

washing the colloid with water, centrifuging, and removing excessive potassium chloride;

carrying out ultrasonic dilution on the washed colloid by adopting distilled water, wherein the concentration after dilution is 6-10mg/mL;

adding cellulose into the diluted colloid, wherein the concentration of the cellulose is 20-30mg/mL;

heating and stirring for 5-7h at 55-65deg.C to obtain KVO paste;

and (3) coating the KVO paste on the conductive substrate by using a clean glass rod, tearing off the adhesive tape, and removing cellulose by heat curing to obtain the KVO electrochromic film.

In a second aspect, the present invention provides a potassium ion doped V ₂ O ₅ Electrochromic films prepared by the preparation method.

In a third aspect, the present invention provides the potassium ion doped V ₂ O ₅ Use of electrochromic films for the preparation of non-active light emitting panels.

The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

1. the electrochromic KVO film prepared by the invention has simplified doping and film forming process, and is prepared by the method of the invention in the purchased commodity V ₂ O ₅ Adding K into the suspension ⁺ To dope metal ions into V ₂ O ₅ In the layered structure of (2), V is enlarged ₂ O ₅ Improves ion mobility kinetics upon electrochromic. And is expressed as V ₂ O ₅ The yellow suspension is changed into orange colloid. The invention uses the characteristics of thickening property of hydroxyethyl cellulose and easy removal at low temperature, and the prepared KVO cellulose paste can be formed into a film by one step by using a bar coating method. Therefore, the KVO film can realize large-scale production and meet the industrial requirement.

2. The electrochromic KVO film prepared by the invention has the characteristics of high color contrast and excellent color switching performance (or quick response speed). Meanwhile, under the condition of being connected with zinc without an external power supply, the orange color can be changed into green color only by 7.8 seconds, and under the condition of supplying power to a two-electrode system, the KVO response time is respectively the fading time t _b Time of coloration t =16.9 s _c =12.9s. Simple synthesis process, high reversible color changing efficiency, long cycle life and the like.

3. The electrochromic KVO film prepared by the invention has excellent cycle performance after the mixed solvent of deionized water and tetramethyl diethyl ether is used as electrolyte, and the cycle times can reach more than 1000 times.

4. The electrochromic KVO film has simple preparation process, low cost and easy obtaining of the used raw materials, and is nontoxic and harmless to the environment. In addition, in view of excellent performance in terms of reversibility to quick response, and simple manufacturing and operating processes, electrochromic KVO films have wide prospects in the aspects of non-active light-emitting flat panel display, complex information coding, electrochromic smart windows and the like.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.

FIG. 1 is a schematic illustration of the process of preparing electrochromic KVO films by the bar coating method of the present invention.

FIG. 2 is an XRD pattern (a) of the KVO electrochromic material prepared in example 1; morphology photograph of KVO electrochromic material (b).

FIG. 3 is a macroscopic photograph showing the reversible color-switching process of the KVO electrochromic film prepared in example 1.

FIG. 4 is a graph showing the transmittance of the KVO electrochromic film prepared in example 1 at various voltages.

FIG. 5 is a graph (a) showing the transmittance of KVO from the coloring process at 520nm and the transmittance of KVO film from the coloring/fading process at 520 nm.

FIG. 6 is a graph (a) showing the 1000 CV cycles of the KVO electrochromic film prepared in example 1, and a graph (b) showing the transmittance spectrum after 1000 cycles at the 520nm position.

FIG. 7 (a) is a graph showing the transmittance of the KVO electrochromic film prepared in example 2 at various voltages; (b) Transmittance curves for the KVO electrochromic films prepared in example 3 at different voltages

FIG. 8 is a graph (a) showing the transmittance of the KVO electrochromic film prepared in comparative example 2 after 1000 CV cycles in an aqueous electrolyte, and a graph (b) showing the transmittance after 1000 CV cycles in an aqueous electrolyte at a wavelength of 520 nm.

FIG. 9 is a photograph of the electrochromic process of a color display based on a KVO electrochromic film.

Detailed Description

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, 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 belongs.

In a first aspect, the present invention provides a potassium ion doped V ₂ O ₅ The preparation method of the electrochromic film comprises the following steps:

will V ₂ O ₅ Dissolving the powder in water, mixing, adding potassium chloride solution to obtain mixed solution, and adding V ₂ O ₅ The concentration of potassium chloride is 50-80g/L, the concentration of potassium chloride is 1-3mol/L, and the colloid is obtained by stirring;

washing the colloid with water, centrifuging, and removing excessive potassium chloride;

carrying out ultrasonic dilution on the washed colloid by adopting distilled water, wherein the concentration after dilution is 6-15mg/mL;

adding cellulose into the diluted colloid, wherein the concentration of the cellulose is 20-30mg/mL;

heating and stirring for 5-7h at 55-65deg.C to obtain KVO paste;

and (3) coating the KVO paste on a conductive substrate by using a clean glass rod, tearing off the adhesive tape, removing cellulose by heat curing, and obtaining the KVO electrochromic film after removing the cellulose.

The cellulose is removed by heating because the cellulose itself is not conductive and the presence of cellulose reduces the electrochemical properties of the electrochromic film.

In some embodiments, the cellulose is cellulose nanocrystals or hydroxyethylcellulose. After the cellulose is added into the KVO colloid, the colloid viscosity can be increased so as to form a KVO paste, and a uniform film can be formed in the rod coating process. And the defect that the ITO conductive glass substrate is not high-temperature resistant can be overcome by utilizing the advantage of easiness in removing cellulose at low temperature, and meanwhile, the energy consumption in the film preparation process is reduced.

Preferably, the cellulose is hydroxyethyl cellulose.

In some embodiments, V in the mixed solution ₂ O ₅ The concentration of (C) is 60-70g/L.

Preferably, the mixing time is 80-100 hours, preferably 90-100 hours.

In some embodiments, the colloid is washed and centrifuged to remove potassium chloride from the colloid at a repetition rate of 4-8 times, preferably 6 times.

Preferably, the rotational speed of the centrifugation is 8000-12000r/min, and the time is 5-15min.

In some embodiments, the conductive substrate is ITO glass, the pre-washing step of which is: sequentially and respectively ultrasonically washing with deionized water, acetone, ethanol and deionized water for 10-20min, and drying with nitrogen.

Preferably, the two sides of the conductive substrate are adhered with adhesive tapes, and when the rod is coated, the two sides of the glass rod are arranged on the adhesive tapes on the two sides.

Further preferably, the adhesive tape is a 3M high tearable adhesive tape, and the number of layers is 1 layer or 2 layers.

The thickness of the coating film was adjusted by the thickness of the adhesive tape.

In some embodiments, the heat gradient for thermally curing the removed cellulose is: 80 ℃,10 min-120 ℃,1 h-160 ℃,1 h-180 ℃ and 12h.

In a second aspect, the present invention provides a potassium ion doped V ₂ O ₅ Electrochromic films prepared by the preparation method.

In a third aspect, the present invention provides the potassium ion doped V ₂ O ₅ The self-coloring method of the electrochromic film comprises the following steps: doping the potassium ion with V ₂ O ₅ Electrochromic film is used as working electrode, zinc foil is used as counter electrode, and Zn (OTf) is used ₂ (Zinc triflate) aqueous solution or Zn (OTf) ₂ And tetramethyl diethyl ether as electrolyte to realize self-coloring of the film;

or, doping the potassium ion with V ₂ O ₅ Electrochromic film is used as working electrode, zinc foil is used as counter electrode and reference electrode, and Zn (OTf) is used ₂ (Zinc triflate) aqueous solution or Zn (OTf) ₂ And tetramethyl diethyl ether as electrolyte to realize electrochromic switching of the film.

In some embodiments, zn (OTf) ₂ The concentration of (C) is 0.3-0.8mol/L.

In some embodiments, the solvent of the electrolyte is a mixed solvent of deionized water and tetramethyl diethyl ether, and the volume ratio of deionized water to tetramethyl diethyl ether is 3-5:1. The organic solvent in the mixed solvent can form on the surface of the film in the process of color changeThe electrolyte interface film is uniform and firm, thereby effectively inhibiting the dissolution of KVO, and the water solvent plays a role in lubrication and is helpful for Zn ²⁺ Is fast in diffusion.

In a third aspect, the present invention provides the potassium ion doped V ₂ O ₅ Use of electrochromic films for the preparation of non-active light emitting panels.

Meanwhile, the experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, are commercially available.

Example 1

A preparation method of an electrochromic KVO film comprises the following steps:

(1) Preparation of KVO Material

ITO glass (10X 40 mm) ² ) Sequentially ultrasonically washing with deionized water, acetone, ethanol and deionized water for 15 minutes, and drying with nitrogen for later use; take 100g V ₂ O ₅ The powder is dissolved in 1.5L of deionized water for magnetic stirring, and the prepared 2mol/L potassium chloride solution is added, and stirring is continued at normal temperature for 96 hours, so that the orange colloid is obtained.

Washing the stirred colloid by deionized water, centrifuging at 10000r/min for 10min, and removing redundant potassium chloride. This process is repeated six times. The washed colloid was diluted to 8mg/mL with distilled water to form a precursor solution. To the diluted colloid, hydroxyethylcellulose was added at a rate of 23mg/mL and magnetically stirred for 6h at 60℃under heating.

(2) Preparation of electrochromic KVO film

The KVO paste is coated on ITO with a layer of 3M high adhesive tape on two sides by a glass rod, the adhesive tape is torn off for heating and curing, and the heating gradient is set to 80 ℃,10 min-120 ℃,1 h-160 ℃,1 h-200 ℃ and 12h. Obtaining the KVO electrochromic film.

(3) Preparation of organic-water mixed electrolyte

Zn (OTf) of 0.5M ₂ (Zinc triflate) is dissolved in a mixed solvent of deionized water and tetramethyl diethyl ether, and the mixing volume ratio is 4:1, and the electrolyte is the electrolyte.

The electrochromic property of the electrochromic KVO film is characterized by using the obtained electrochromic KVO film:

(4) And (3) taking the film prepared in the step (2) as a working electrode, and taking zinc foil as a counter electrode and a reference electrode, and putting the zinc foil into the electrolyte prepared in the step (3). The electrochemical workstation is connected to perform electrochemical performance characterization under a two-electrode system. And simultaneously, an electrochemical workstation is used together with a UV-Vis spectrometer for electrochromic performance characterization.

V doped with K of the invention ₂ O ₅ The structure of the material was determined by X-ray diffractometer, as shown in FIG. 2a, and the composition of the obtained material was K as seen in XRD pattern _1.11 V ₃ O ₈ . The morphology of the material was observed by transmission electron microscopy, as shown in FIG. 2b, the KVO morphology was rod-like and initial sheet-like V ₂ O ₅ Differently, it is shown that the doping of K causes V ₂ O ₅ Resulting in a topographical change. The thin film exhibits different colors when different voltages between 0.2 and 2.0V are applied through the electrochemical workstation, and is green when the applied voltage is 0.2V as shown in fig. 3; when the applied voltage is 1.2V, the film is yellow; when a voltage of 2.0V was applied, the film was red.

When the color switching in-situ monitoring is performed by a UV-Vis spectrometer, the transmittance curves of different colors are shown in fig. 4, and the transmittance peak value can be blue shifted with the decrease of the applied voltage. Indicating Zn ²⁺ The process of inserting (coloring) and extracting (bleaching) realizes reversible color switching of the KVO film

). At 520nm wavelength, the transmittance modulation range of the KVO film prepared in the embodiment is 25.8%, and the maximum transmittance is 68%. The pattern under the film can be clearly distinguished. And zinc is adopted as an electrochromic anode, and spontaneous coloring process (figure 5 a) of the KVO film can be realized by utilizing oxidation-reduction potential between the zinc and the KVO, wherein the coloring time is 8.8s. Color switching time t during bleaching (orange) and coloring (green) _b And t _c Respectively defined as the time required to achieve 90% of the final modulation, respectively 16.9sAnd 12.9s (FIG. 5 b).

The cycle life of the film was measured by cyclic voltammetry, the KVO film retained 55% of its initial capacity (fig. 6 a), and had an optical contrast of 19% after 1000 CV cycles (fig. 6 b) showing excellent reversibility and repeatability.

Example 2

A preparation method of an electrochromic KVO film comprises the following steps:

(1) Preparation of KVO Material

ITO glass (10X 40 mm) ² ) Sequentially ultrasonically washing with deionized water, acetone, ethanol and deionized water for 15 minutes, and drying with nitrogen for later use; take 100g V ₂ O ₅ The powder is dissolved in 1.5L deionized water for magnetic stirring, and the prepared 1mol/L potassium chloride solution is added, and stirring is continued at normal temperature for 5 days, so as to obtain orange colloid.

Washing the stirred colloid by deionized water, centrifuging at 10000r/min for 10min, and removing redundant potassium chloride. This process was repeated eight times. The washed colloid was diluted to 15mg/mL with distilled water to form a precursor solution. To the diluted colloid, hydroxyethylcellulose was added at a rate of 23mg/mL and magnetically stirred for 6h at 60℃under heating.

(2) The electrochromic KVO film was prepared as in example 1;

(3) The organic-water mixed electrolyte was prepared as in example 1;

the electrochromic property of the electrochromic KVO film is characterized by using the obtained electrochromic KVO film: electrochromic characterization method As in example 1, the films still exhibited reversible color switching (orange) when different voltages between 0.2 and 2.0V were applied through the electrochemical workstation

Yellow->

Green). As the colloid concentration in the film was increased to 15mg/ml, the KVO film prepared in this example was transparent at a wavelength of 520nmThe overrate modulation range was 18.5% and the maximum transmission was 38% (fig. 7 a).

Example 3

A preparation method of an electrochromic KVO film comprises the following steps:

(1) Preparation of KVO Material

ITO glass (10X 40 mm) ² ) Sequentially ultrasonically washing with deionized water, acetone, ethanol and deionized water for 15 minutes, and drying with nitrogen for later use; take 100g V ₂ O ₅ The powder is dissolved in 1.5L of deionized water for magnetic stirring, and the prepared 2.5mol/L potassium chloride solution is added, and stirring is continued at normal temperature for 5 days, so that the orange colloid is obtained.

Washing the stirred colloid by deionized water, centrifuging at 10000r/min for 10min, and removing redundant potassium chloride. This process was repeated eight times. The washed colloid was diluted to 5mg/mL with distilled water to form a precursor solution. To the diluted colloid, hydroxyethylcellulose was added at a rate of 23mg/mL and magnetically stirred for 6h at 60℃under heating.

(2) The electrochromic KVO film was prepared as in example 1.

(3) Preparation of organic-water mixed electrolyte

Zn (OTf) of 0.3M ₂ (Zinc triflate) is dissolved in a mixed solvent of deionized water and tetramethyl diethyl ether, and the mixing volume ratio is 4:1, and the electrolyte is the electrolyte. The organic-water mixed electrolyte was prepared in the same manner as in example 1.

The electrochromic property of the electrochromic KVO film is characterized by using the obtained electrochromic KVO film:

electrochromic characterization method As in example 1, the films still exhibited reversible color switching (orange) when different voltages between 0.2 and 2.0V were applied through the electrochemical workstation

Yellow->

Green). Because the colloid concentration in the film was reduced to 5mg/ml,therefore, the KVO film prepared in this example had a transmittance modulation range of 18.2% and a maximum transmittance of 75% at a wavelength of 520nm (FIG. 7 b). />

Comparative example 1

The differences from example 1 are: the cellulose type in the step (1) is replaced by cellulose nanofiber, other steps are unchanged, the corresponding KVO paste is carbonized during high-temperature treatment after being prepared on ITO glass by a bar coating method, and the film is blackened and cannot be completely decarbonized at 180 ℃, so that the electrochromic property of the film is damaged.

Comparative example 2

The difference from example 1 is that the electrolyte solvent in step (3) is replaced with water.

The thin film prepared in this comparative example has poor cycle stability in aqueous electrolyte; after 1000 CV cycles the KVO material was completely shed and dissolved into the water.

1000 CV cycles of KVO in aqueous electrolyte as shown in FIG. 8 (a), the CV curve tends to be a straight line after 1000 cycles, indicating that the charge capacity is almost zero at this time. And the optical contrast after 1000 CVs was also zero (fig. 8 b).

Application example 1

KVO electrochromic display based on color superposition effect

The preparation method comprises the following steps:

(1) Device assembly

Cleaning: two pieces of 5X 5cm were taken ² Sequentially ultrasonically washing ITO glass with deionized water, acetone, ethanol and deionized water for 15 minutes, and drying with nitrogen for later use;

film forming: as described in example 1, step (2), the two glass center bars were each coated with 2X 2cm ² A KVO electrochromic film of (c);

and (3) assembling: and respectively pasting conductive copper adhesive tapes with the width of 1cm on the periphery of the two pieces of prepared ITO glass, compacting, and pasting two layers of 3M transparent double-sided adhesive tapes on the conductive copper adhesive tapes, wherein the double-sided adhesive tapes are required to cover the copper adhesive tapes just completely in width, so that the adhesive tapes cannot be contacted with electrolyte. Then, a piece of zinc foil frame is cut out, so that the periphery of the zinc foil frame can be exposed inwards for a distance of 3-5mm when the zinc foil frame is stuck on the double-sided adhesive tape of glass, and the KVO film cannot be blocked. Finally, another piece of ITO glass which is not pasted with a zinc frame is covered on the glass, and the two pieces of glass are pressed to form an electrochromic device;

compacting: compacting the device under a weight for 4-6 days;

preparing a gel electrolyte: as described in step (3) of example 1, 9% by mass of polyvinyl alcohol (PVA Mw-195,000) was added thereto and stirred until clear and transparent;

injecting electrolyte: taking out the compacted electrochromic device, and injecting gel electrolyte into the cavity of the device by using a syringe;

(2) Electrodeposition for preparing flexible PB/ITO/PET film with patterns

A patterned flexible PB/ITO/PET film was obtained as described in example 1, step (1).

(3) Color expression for KVO electrochromic displays

The advantage of independently adjusting the color of the upper and lower KVO electrochromic films in the device is utilized, namely, each electrode can realize three-color expression (orange

Yellow->

Green) so that six color expression of the device (e.g., orange, amber, yellow, brown, yellow-green, and green) can be achieved by the color accumulation effect when the two colors are superimposed. The photograph of the electrochromic process is shown in fig. 9, in which the display appears dark green when both layers of electrochromic film are green (fig. 9 a), yellow-green when one of the layers is green and the other is yellow (fig. 9 b), brown when one of the layers is green and the other is orange (fig. 9 c), dark yellow when both layers are yellow (fig. 9 d), amber when one of the layers is orange and yellow (fig. 9 e), and orange when both layers are orange. />

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. Potassium ion doped V ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: the method comprises the following steps:

will V ₂ O ₅ Dissolving the powder in water, mixing, adding potassium chloride solution to obtain mixed solution, and adding V ₂ O ₅ The concentration of potassium chloride is 50-80g/L, the concentration of potassium chloride is 1-3mol/L, and the colloid is obtained by stirring;

washing the colloid with water, centrifuging, and removing excessive potassium chloride;

carrying out ultrasonic dilution on the washed colloid by adopting distilled water, wherein the concentration after dilution is 6-10mg/mL;

adding cellulose into the diluted colloid, wherein the concentration of the cellulose is 20-30mg/mL;

heating and stirring for 5-7h at 55-65deg.C to obtain KVO paste;

and (3) coating the KVO paste on the conductive substrate by using a clean glass rod, tearing off the adhesive tape, and removing cellulose by heat curing to obtain the KVO electrochromic film.

2. The potassium ion doped V of claim 1 ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: the cellulose is cellulose nanocrystalline or hydroxyethyl cellulose.

3. The potassium ion doped V of claim 1 ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: v in the mixed solution ₂ O ₅ The concentration of (2) is 60-70g/L;

preferably, the mixing time is 80-100 hours, preferably 90-100 hours.

4. The potassium ion doped V of claim 1 ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: washing the colloid, and centrifuging to remove potassium chloride for 4-8 times;

preferably, the rotational speed of the centrifugation is 8000-12000r/min, and the time is 5-15min.

5. The potassium ion doped V of claim 1 ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: the conductive substrate is ITO glass, and the pre-washing steps are as follows: sequentially respectively ultrasonically washing with deionized water, acetone, ethanol and deionized water for 10-20min, and drying with nitrogen;

preferably, the two sides of the conductive substrate are adhered with adhesive tapes, and when the rod is coated, the two sides of the glass rod are arranged on the adhesive tapes on the two sides.

6. The potassium ion doped V of claim 1 ₂ O ₅ The preparation method of the electrochromic film is characterized by comprising the following steps: the heating gradient for thermally curing and removing cellulose is as follows: 80 ℃,10 min-120 ℃,1 h-160 ℃,1 h-180 ℃ and 12h.

7. Potassium ion doped V ₂ O ₅ An electrochromic film characterized by: prepared by the preparation method of any one of claims 1 to 6.

8. The potassium ion doped V of claim 7 ₂ O ₅ A method for self-coloring an electrochromic film, characterized by: the method comprises the following steps: doping the potassium ion with V ₂ O ₅ Electrochromic film is used as working electrode, zinc foil is used as counter electrode, and Zn (OTf) is used ₂ Aqueous solutions or Zn (OTf) ₂ And tetramethyl diethyl ether as electrolyte to realize self-coloring of the film;

or, doping the potassium ion with V ₂ O ₅ Electrochromic film as working electrode, zinc foil as counter electrode andreference electrode using Zn (OTf) ₂ Aqueous solutions or Zn (OTf) ₂ And tetramethyl diethyl ether as electrolyte to realize electrochromic switching of the film.

9. The potassium ion doped V of claim 8 ₂ O ₅ A method for self-coloring an electrochromic film, characterized by: zn (OTf) ₂ The concentration of (2) is 0.3-0.8mol/L;

preferably, the solvent of the electrolyte is a mixed solvent of deionized water and tetramethyl diethyl ether, and the volume ratio of the deionized water to the tetramethyl diethyl ether is 3-5:1.

10. The potassium ion doped V of claim 7 ₂ O ₅ Use of electrochromic films for the preparation of non-active light emitting panels.

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