Preparation method of poly-3,4-ethylenedioxythiophene doped vanadium pentoxide electrochromic film

Abstract

The application belongs to the field of electrochromic materials, and relates to a preparation method of a 3,4-vinylenedioxythiophene doped vanadium pentoxide electrochromic film. 3,4-vinylenedioxythiophene is added to an aqueous dispersion of vanadium pentoxide, and a continuous stirring reaction is performed to make the 3,4-vinylenedioxythiophene perform a polymerization reaction and make poly-3,4-vinylenedioxythiophene intercalate V2O5; the material after the continuous stirring reaction is subjected to centrifugal washing, and then the precipitate after the centrifugal washing is added to water and ultrasonically treated to prepare a precursor solution; the precursor solution is sprayed on the surface of a conductive substrate, and then annealing is performed, and the film is obtained. The film provided by the application simultaneously improves electrochemical performance, optical performance and electrochromic performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochromic materials, and relates to a preparation method of a poly-3,4-ethylenedioxythiophene (PEDOT) doped vanadium pentoxide electrochromic film. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of generally presenting the context of the application. The information disclosed in this Background section is not to be necessarily taken as an acknowledgement or any form of suggestion that this information forms part of the prior art already known to a person skilled in the art.

[0003] Electrochromic (EC) materials are characterized by reversible and persistent stable changes in optical properties under the driving of external voltage, which is manifested as changes in color and transparency.

[0004] Electrochromic glass (smart window) is a new type of energy-saving building material, which is generally composed of glass, transparent conductive layer, electrochromic layer, electrolyte layer, ion storage layer, transparent conductive layer and glass. V2O5 material is the only oxide material with bipolar electrochromic properties that can serve as both a color-changing material and an ion storage material. Its typical layered structure is conducive to the insertion and extraction of metal ions during the redox process. V2O5 material is the most widely studied oxide among electrochromic materials. It can exhibit a variety of color changes from yellow, green, blue to intermediate states following voltage changes, thus having the characteristics of high color contrast and rich color transformation. However, as an electrode material, V2O5 also has many problems such as poor cycle performance, long response time, and low transmittance. In order to improve the electrochemical performance of electrode materials, there are four typical methods to improve the electrochemical performance of electrode materials; (1) preparing nanostructured vanadium pentoxide electrode material, which can significantly shorten the diffusion distance of lithium ions and increase the contact area between the electrode and the electrolyte; (2) improving the conductivity of vanadium pentoxide by adding carbon materials; (3) improving the electrochemical stability of vanadium pentoxide by surface coating; (4) doping metal cations. Studies have shown that doping metal cations is a very effective and promising method to improve the electrochemical performance of materials. However, doping metal cations only improves the electrochemical performance of V2O5 material, and rarely changes the electrochromic performance of V2O5. SUMMARY

[0005] In order to solve the problems of the prior art, the present application aims to provide a preparation method of poly-3,4-ethylenedioxythiophene doped vanadium pentoxide electrochromic film, which can improve the electrochemical, optical and electrochromic performance of the film to different degrees, such as electrochemical activity, light modulation range, response time or cycle stability, so as to obtain a zinc-type electrochromic device with more excellent performance.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] In a first aspect, the present application provides a preparation method of poly-3,4-ethylenedioxythiophene doped vanadium pentoxide electrochromic film, which comprises the following processes:

[0008] 3,4-ethylenedioxythiophene is added to the aqueous dispersion of vanadium pentoxide, and the reaction is continuously stirred to make 3,4-ethylenedioxythiophene perform in-situ polymerization and make poly-3,4-ethylenedioxythiophene intercalate V2O5;

[0009] The material after the continuous stirring reaction is centrifuged and washed, and then the precipitate after the centrifugal washing is added to water and ultrasonically treated to prepare a precursor solution;

[0010] The precursor solution is sprayed on the surface of the conductive substrate, and then annealing is performed.

[0011] The present application uses the oxidizing property of vanadium pentoxide to make 3,4-ethylenedioxythiophene perform in-situ polymerization and make poly-3,4-ethylenedioxythiophene intercalate V2O5 to obtain a poly-3,4-ethylenedioxythiophene doped vanadium pentoxide composite, after removing the unreacted V2O5 and EDOT, the composite is sprayed on the surface of the conductive substrate, and then annealing is performed, which not only makes the poly-3,4-ethylenedioxythiophene doped vanadium pentoxide composite form a film, but also makes the film adhere more firmly to the conductive substrate.

[0012] In another aspect, the present application provides a poly-3,4-ethylenedioxythiophene doped vanadium pentoxide film obtained by the above-mentioned preparation method.

[0013] In a third aspect, the present application provides an electrochromic cathode, which comprises a conductive substrate and the above-mentioned poly-3,4-ethylenedioxythiophene doped vanadium pentoxide film attached to the surface of the conductive substrate.

[0014] In a fourth aspect, the present application provides an electrochromic device, which comprises an anode, a cathode and an electrolyte, the anode and the cathode are placed in the electrolyte, the anode is a metal zinc, and the cathode is the above-mentioned electrochromic cathode or contains the above-mentioned poly-3,4-ethylenedioxythiophene doped vanadium pentoxide film.

[0015] The application researches and finds that the poly-3,4-ethylenedioxythiophene doped vanadium pentoxide thin film provided by the application can realize electrochromism when used as a zinc-type electrochromic cathode material, wherein a constant voltage of 0.1±0.02 V can realize a coloring process, and a constant voltage of 2.2±0.02 V can realize a bleaching process.

[0016] In a fifth aspect, the application provides application of the poly-3,4-ethylenedioxythiophene doped vanadium pentoxide thin film, the electrochromic cathode or the electrochromic device in an electrochromic window.

[0017] The application has the following beneficial effects:

[0018] 1. The poly-3,4-ethylenedioxythiophene doped vanadium pentoxide thin film material provided by the application has the advantages of high electrochemical activity, wide light modulation range, high color contrast, short response time, fast color change speed, good cycle stability, long service life and the like compared with a vanadium pentoxide thin film.

[0019] 2. The preparation method of the poly-3,4-ethylenedioxythiophene doped vanadium pentoxide thin film material provided by the application is simple and convenient for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings accompanying the specification of the application form a part of the application and serve to provide further understanding of the application, and the illustrative embodiments of the application and their descriptions serve to explain the application, and do not constitute an improper limitation on the application.

[0021] Figure 1 A photo of a PEDOT@V2O5 thin film attached to ITO glass when annealing is completed in Example 1 of the application.

[0022] Figure 2 Photos of the PEDOT@V2O5 thin film of Example 1 of the application showing different colors under different voltages, A is 0.1 V, B is 1.2 V, and C is 2.2 V.

[0023] Figure 3 Scanning electron microscope photos of the PEDOT@V2O5 and ITO / PEDOT@V2O5 of Example 1 of the application.

[0024] Figure 4 Transmission electron microscope photos and element distribution images of the PEDOT@V2O5 of Example 1 of the application, A is a bright-field transmission electron microscope photo, B is a dark-field transmission electron microscope photo, C is a sulfur element distribution image, D is an oxygen element distribution image, and E is a vanadium element distribution image.

[0025] Figure 5Cyclic voltammogram (CV) images of PEDOT@V2O5(A), V2O5(B) prepared for Example 1 and Comparative Example 1 in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively.

[0026] Figure 6 Visible light transmission spectrum images of PEDOT@V2O5(A), V2O5(B) prepared for Example 1 and Comparative Example 1 under different colors.

[0027] Figure 7 Response time images of PEDOT@V2O5(A), V2O5(B) prepared for Example 1 and Comparative Example 1 in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution (pH≈5), respectively.

[0028] Figure 8 Cyclic stability images of PEDOT@V2O5(A), V2O5(B) prepared for Example 1 and Comparative Example 1 in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0030] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0031] In view of the fact that the existing modification method of V2O5 material is difficult to simultaneously improve its electrochemical performance and electrochromic performance, the present application provides a preparation method of poly-3,4-ethylenedioxythiophene doped vanadium pentoxide electrochromic film.

[0032] In a typical embodiment of the present application, a preparation method of poly-3,4-ethylenedioxythiophene doped vanadium pentoxide electrochromic film is provided, which comprises the following processes:

[0033] adding 3,4-vinyl dioxythiophene to the water dispersion of vanadium pentoxide, continuously stirring the reaction, allowing 3,4-vinyl dioxythiophene to conduct in-situ polymerization, and allowing poly-3,4-vinyl dioxythiophene to intercalate V2O5;

[0034] centrifuging and washing the material after continuously stirring the reaction, and then adding the precipitate after centrifuging and washing to water and ultrasonically treating to prepare a precursor solution;

[0035] spraying the precursor solution on the surface of a conductive substrate, and then annealing to obtain the product.

[0036] In some embodiments, the ratio of vanadium pentoxide to 3,4-vinyl dioxythiophene is 2.0-2.5 g: 1 mL.

[0037] In some embodiments, the time for continuously stirring the reaction is 115-125 h.

[0038] In some embodiments, ethanol and water are used for centrifuging and washing. Specifically, the centrifugation speed is 7000-9000 r / min, and the single centrifugation time is 2-4 min.

[0039] In some embodiments, the time for ultrasonic treatment is 0.5-1 h.

[0040] In some embodiments, the concentration of the precursor solution is 8-15 mg / mL.

[0041] In some embodiments, the conductive substrate is conductive glass. Specifically, the conductive substrate is ITO glass.

[0042] In some embodiments, the annealing temperature is 140-190 °C, and the annealing time is 15-25 h.

[0043] Another embodiment of the present application provides a poly-3,4-vinyl dioxythiophene doped vanadium pentoxide thin film obtained by the above preparation method.

[0044] A third embodiment of the present application provides an electrochromic cathode, which comprises a conductive substrate and the above poly-3,4-vinyl dioxythiophene doped vanadium pentoxide thin film attached to the surface of the conductive substrate.

[0045] A fourth embodiment of the present application provides an electrochromic device, which comprises an anode, a cathode, and an electrolyte, the anode and the cathode are placed in the electrolyte, the anode is metal zinc, and the cathode is the above electrochromic cathode or contains the above poly-3,4-vinyl dioxythiophene doped vanadium pentoxide thin film.

[0046] In some embodiments, the electrolyte in the electrolyte solution is Zn(ClO4)2and LiClO4, and the solvent is propylene carbonate (PC). Specifically, the concentration of Zn(ClO4)2in the electrolyte solution is 0.05-0.15 M, and the concentration of LiClO4is 0.75-0.85 M. The unit M refers to mol / L.

[0047] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples and comparative examples.

[0048] Example 1

[0049] A poly-3,4-ethylenedioxythiophene (PEDOT) doped vanadium pentoxide thin film, and a preparation method thereof, includes the following steps:

[0050] (1) 7 g of commercial vanadium pentoxide was added to 200 ml of a deionized water solution, stirred for 30 min, and then 3 ml of 3,4-ethylenedioxythiophene was added and stirred for 5 days to obtain a dark green solution.

[0051] (2) The dark green solution was washed with ethanol and deionized water by centrifugation twice in sequence, the centrifugation speed was 8000 r / min, and the single centrifugation time was 3 min; after centrifugation and washing, the precipitate was added with deionized water, and then ultrasonic treatment was performed for 1 h to prepare a precursor solution (concentration of 10 mg / mL).

[0052] (3) 40 mL of the precursor solution of step (2) was uniformly sprayed on ITO glass (5 cm x 5 cm) by using a spraying method, and then annealed at 180°C for 20 h to form a poly-3,4-ethylenedioxythiophene doped vanadium pentoxide (PEDOT@V2O5) thin film on the ITO glass.

[0053] The PEDOT@V2O5 thin film of Example 1 was characterized:

[0054] The PEDOT@V2O5 thin film attached to the ITO glass at the completion of annealing showed a dark green color, as shown in Figure 1 .

[0055] The power supply was connected to the cathode and the anode by wires, the thin film adhered to the ITO glass substrate served as the cathode, and metallic zinc served as the anode, and the detection was performed using an electrochemical workstation in a Zn(ClO4)2(0.1 M) and LiClO4(0.8 M) PC solution. The PEDOT@V2O5 thin film showed a gray color, an olive color, and a dark green color at voltages of 0.1 V, 1.2 V, and 2.2 V, respectively, as shown in Figure 2As shown, the PEDOT@V2O5 film is gray at 0.1 V, and starts to fade to olive color at 1.2 V, and completely fades to the original color, i.e., dark green, at 2.2 V.

[0056] The microstructure of the PEDOT@V2O5 film was analyzed by scanning electron microscopy (SEM), as shown in FIG. 2A. Figure 3 As shown, the PEDOT@V2O5 is a nanofiber (rod) structure.

[0057] Transmission electron microscopy (TEM) and elemental analysis images were used to analyze the microstructure and uniformity of doping, as shown in FIG. 3A. Figure 4 As shown in FIG. 3A, a single rod structure of PEDOT@V2O5 was captured, which is consistent with the result of scanning electron microscopy. Figure 4 As shown in FIG. 3C-E, the PEDOT@V2O5 nanorod contains S, O, and V elements, and they are uniformly distributed.

[0058] Example 2

[0059] A poly(3,4-ethylenedioxythiophene) (PEDOT) doped vanadium pentoxide film, and a preparation method thereof, includes the following steps:

[0060] (1) 7 g of commercial vanadium pentoxide was added to 200 ml of a deionized water solution, stirred for 30 min, and then 3 ml of 3,4-ethylenedioxythiophene was added and mixed for 5 days to obtain a dark green solution.

[0061] (2) The dark green solution was sequentially washed with ethanol and deionized water for 2 times each by centrifugation at a speed of 8000 r / min for 3 min each time. The precipitate after centrifugal washing was added to deionized water and then ultrasonically treated for 0.5 h to prepare a precursor solution (concentration of 8 mg / mL).

[0062] (3) 40 ml of the precursor solution of step (2) was uniformly sprayed on an ITO glass (5 cm x 5 cm) by a spraying method, and then annealed at 150°C for 20 h to form a poly(3,4-ethylenedioxythiophene) doped vanadium pentoxide (PEDOT@V2O5) film on the ITO glass.

[0063] Example 3

[0064] A poly(3,4-ethylenedioxythiophene) (PEDOT) doped vanadium pentoxide film, and a preparation method thereof, includes the following steps:

[0065] (1) 7 g of commercial vanadium pentoxide was added to 200 ml of a deionized water solution, stirred for 30 min, and then 3 ml of 3,4-ethylenedioxythiophene was added and mixed for 5 days to obtain a dark green solution.

[0066] (2) The dark green solution was washed twice by centrifugation with ethanol and deionized water, respectively. The centrifugation speed was 8000 r / min and the centrifugation time was 3 min. The precipitate after centrifugation and washing was added to deionized water and then sonicated for 1 h to prepare a precursor solution (concentration of 15 mg / mL).

[0067] (3) 40 mL of the precursor solution from step (2) was uniformly sprayed onto ITO glass (5 cm × 5 cm) by spraying, and then annealed at 160 °C for 20 h to form a poly(3,4-ethylenedioxythiophene) doped vanadium pentoxide (PEDOT@V2O5) film on the ITO glass.

[0068] Comparative Example 1

[0069] The method for preparing vanadium pentoxide thin films includes the following steps:

[0070] (1) Add 7g of commercial vanadium pentoxide to 200ml of deionized water solution, stir for 30min, and continue mixing and stirring for 5 days;

[0071] (2) The dispersion obtained in step (1) was centrifuged twice with ethanol and twice with deionized water, respectively, at a speed of 8000 r / min. The centrifugation time was 3 min each time. After ultrasonic treatment for 1 h, deionized water was added to prepare a precursor solution (concentration of 10 mg / mL).

[0072] (3) A precursor solution was uniformly sprayed onto ITO glass, and then annealed at 180°C for 20 hours to form a vanadium pentoxide thin film on the ITO glass.

[0073] Electrochemical and optical tests (Example 1 and Comparative Example 1)

[0074] (1) The power supply was connected to the cathode and anode by wires. The thin film adhered to the ITO glass substrate was used as the cathode and the zinc metal was used as the anode. PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) were measured by cyclic voltammetry in Zn(ClO4)2 (0.1M) and LiClO4 (0.8M)-PC solutions, respectively, with a scan rate of 50mV / s.

[0075] like Figure 5 As shown, compared with V2O5 (Comparative Example 1), the current density in the CV curve of the PEDOT-doped film is higher, indicating that PEDOT@V2O5 (Example 1) has higher electrochemical activity.

[0076] (2) The visible light transmittance spectra of PEDOT@V2O5 films at 0.2V, 1.2V, 2.2V constant voltage (different colors) were measured using a visible light spectrophotometer;

[0077] As shown in FIG. 1, the color of PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) at 0.2V, 1.2V, 2.2V constant voltage is the same, which is gray olive color. The results show that the lower the PEDOT element doping content, the lower the light modulation range of the film. Figure 6 As shown in FIG. 2, the light modulation range of PEDOT@V2O5 (Example 1) at 400nm is the largest, which is about 27.1%; the light modulation range of V2O5 (Comparative Example 1) at 400nm is about 13.3%. The above measurement results show that the maximum light modulation range of the film doped with PEDOT is significantly increased compared with the film doped with PEDOT.

[0078] (3) The response time and cycle stability of PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) were measured using an electrochemical workstation combined with a visible light spectrophotometer in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively.

[0079] As shown in FIG. 3, the response time of PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) was measured for multiple cycles in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively, each cycle being 120 seconds, i.e. 60 seconds of 0.1V constant voltage and 60 seconds of 2.2V constant voltage being applied, respectively. The response time is defined as the time required to reach 90% of the final transmittance. Among them, the coloring time of PEDOT@V2O5 film (Example 1) at 400nm is 9.2s, and the bleaching time is 9.6s, which is the fastest among the two; the coloring time of V2O5 film (Comparative Example 1) at 524nm is 16.2s, and the bleaching time is 31.7s.

[0080] Figure 7 As shown in FIG. 4, 1000 CV cycles of PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) were carried out in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively, with a scan rate of 50mV / s. The ratio of the area enclosed by the CV curve is the ratio of the capacity of the electrode. The measurement results show that the attenuation of PEDOT@V2O5 (Example 1) after 1000 CV cycles is the smallest, and the capacity retention rate is the highest; while the attenuation of V2O5 (Comparative Example 1) is obviously larger, and the capacity retention rate is lower.

[0081] As shown in FIG. 4, 1000 CV cycles of PEDOT@V2O5 (Example 1) and V2O5 (Comparative Example 1) were carried out in Zn(ClO4)2(0.1M) and LiClO4(0.8M)-PC solution, respectively, with a scan rate of 50mV / s. The ratio of the area enclosed by the CV curve is the ratio of the capacity of the electrode. The measurement results show that the attenuation of PEDOT@V2O5 (Example 1) after 1000 CV cycles is the smallest, and the capacity retention rate is the highest; while the attenuation of V2O5 (Comparative Example 1) is obviously larger, and the capacity retention rate is lower. Figure 8 ​​

[0082] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a poly(3,4-ethylenedioxythiophene) doped vanadium pentoxide electrochromic thin film, characterized in that, The process comprises the following steps: adding 3, 4-ethylenedioxythiophene to a water dispersion of vanadium pentoxide, continuously stirring the reaction, allowing the 3, 4-ethylenedioxythiophene to undergo in-situ polymerization, and allowing poly-3, 4-ethylenedioxythiophene to intercalate V2O5; centrifuging and washing the continuously stirred reaction mixture, then adding the centrifuged and washed precipitate to water and ultrasonically treating to prepare a precursor solution; spraying the precursor solution onto the surface of a conductive substrate, then annealing to obtain the product; the vanadium pentoxide and 3, 4-ethylenedioxythiophene are added in a ratio of 2.0-2.5 g:1 mL, the continuously stirred reaction is carried out for 115-125 h; the ultrasonic treatment is carried out for 0.5-1 h; the concentration of the precursor solution is 8-15 mg / mL, the conductive substrate is conductive glass; or, the conductive substrate is ITO glass; the annealing temperature is 150-190 ℃, and the annealing time is 15-25 h.

2. The method for preparing the poly(3,4-ethylenedioxythiophene)-doped vanadium pentoxide electrochromic thin film as described in claim 1, characterized in that, ethanol and water are used for centrifuging and washing.

3. A thin film of poly-3, 4-ethylenedioxythiophene doped with vanadium pentoxide, characterized by, obtained by the preparation method of any one of claims 1-2.

4. An electrochromic cathode characterized by, a conductive substrate and a poly-3, 4-ethylenedioxythiophene doped vanadium pentoxide thin film attached to the surface of the conductive substrate, as claimed in claim 3.

5. An electrochromic device, characterized in that, an anode, a cathode, and an electrolyte, the anode and the cathode being placed in the electrolyte, the anode being metal zinc, and the cathode containing a poly-3, 4-ethylenedioxythiophene doped vanadium pentoxide thin film, as claimed in claim 3.

6. The electrochromic device of claim 5, wherein the electrolyte is Zn(ClO4)2 and LiClO4, and the solvent is propylene carbonate; or, in the electrolyte, the concentration of Zn(ClO4)2 is 0.05-0.15 M, and the concentration of LiClO4 is 0.75-0.85 M.

7. Use of the poly-3, 4-ethylenedioxythiophene doped vanadium pentoxide thin film of any one of claims 1-3, the electrochromic cathode of claim 4, or the electrochromic device of claim 5 in electrochromic glass.

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