Silicon dioxide gel integrated electrochromic device and preparation method thereof

Abstract

The invention belongs to the technical field of electrochromic devices, and particularly relates to a silicon dioxide gel integrated electrochromic device and a preparation method thereof. The integrated electrochromic device is of a three-layer structure which is a transparent conductive substrate, color-changing gel and a transparent conductive substrate. The color-changing gel is composite gel of silicon dioxide gel and a metal oxygen cluster material, proper redox equilibrium species and ionic liquid are added, and an integrated electrochromic device with high optical contrast and ultra-long cycle stability is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochromic devices, and in particular relates to an integrated electrochromic device of silica gel and a preparation method thereof. Background Art

[0002] Traditional electrochromic devices are mostly five-layer sandwich structures: a transparent conductive electrode (I), an electrochromic layer, an electrolyte layer, an ion storage layer, and a transparent conductive electrode (II). These structures are very complex and the preparation process is tedious. Existing integrated electrochromic devices are mostly organic color-changing materials, such as viologen and its derivatives, combined with organic gels. Prolonged exposure of organic materials to ultraviolet light can lead to a decrease in their stability. Metal oxide clusters, as inorganic color-changing materials, have attracted widespread attention in the electrochromic field due to their good solubility in water, excellent redox properties, and UV stability. Silica gel, with its high transparency, good dispersibility, and adsorption properties, can serve as an excellent carrier material. Combining metal oxide clusters with silica gel is expected to combine the advantages of both, creating an integrated electrochromic gel, improving the electrochromic performance of metal oxide clusters and enhancing their practical application value. Summary of the Invention

[0003] The purpose of the present invention is to provide an integrated electrochromic device of silica gel and a preparation method thereof, wherein the color-changing gel has good electrochromic performance and ultra-long cycle stability.

[0004] The technical solution adopted in the present invention is:

[0005] The structure of an integrated electrochromic device of silica gel is divided into three layers, namely: a transparent conductive substrate, a color-changing gel, and a transparent conductive substrate. The color-changing gel is sandwiched between two transparent conductive substrates; the color-changing gel is a mixture of silica gel, metal oxygen clusters, redox equilibrium species and ionic liquid solution; the metal oxygen clusters are PW 12 、P2W 18 or phosphomolybdic acid, and the redox equilibrium species are lithium iodide, ferrocene, or tetramethylthiourea.

[0006] Furthermore, in the above-mentioned integrated electrochromic device of silica gel, the transparent conductive substrate is FTO conductive glass or ITO conductive glass.

[0007] Furthermore, in the above-mentioned integrated electrochromic device of silica gel, the ionic liquid solution is a lithium bis(trifluoromethanesulfonyl)imide propylene carbonate solution or a tetramethylammonium hexafluorophosphate propylene carbonate solution.

[0008] The method for preparing the integrated electrochromic device of silica gel described in any one of the above comprises the following steps:

[0009] 1) Preparation of silica gel: Add 3.0 g of sodium silicate to deionized water and dissolve by stirring at room temperature at 500 r / min. Once completely dissolved, add 5 mL of concentrated hydrochloric acid while stirring to form a translucent silica gel. Allow to age at room temperature for 20-24 h to obtain the silica gel.

[0010] 2) Preparation of color-changing gel: Silica gel, metal oxygen cluster solution, ionic liquid solution, and redox equilibrium species solution are mixed uniformly to form a color-changing gel;

[0011] 3) The color-changing gel is sandwiched between two transparent conductive substrates to assemble an integrated electrochromic device.

[0012] Furthermore, the above-mentioned preparation method, step 2) specifically comprises the following steps: adding 1 mL of the metal oxide cluster solution to the silica gel, stirring at room temperature for 10-20 minutes at a speed of 500 r / min; then adding 1 mL of the ionic liquid solution to the mixed system, stirring at room temperature for 10-20 minutes at a speed of 500 r / min; then adding 1 mL of the redox equilibrium species solution to the mixed system, stirring at room temperature for 2-3 hours at a speed of 500 r / min to obtain a color-changing gel, and then ultrasonicating the color-changing gel for 30 minutes.

[0013] The beneficial effects of the present invention are:

[0014] 1. This invention utilizes highly transparent silica gel as the gel backbone for the integrated electrochromic material and mixes metal oxide clusters with the gel, simplifying the structure of the electrochromic device. Selecting a suitable redox-balanced material enhances the device's coloring and fading capabilities, resulting in an integrated electrochromic device with exceptionally long cycling stability.

[0015] 2. The device of the present invention is simple to prepare, easy to operate and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the integrated electrochromic device of the present invention.

[0017] Figure 2 This is an optical contrast graph of the integrated electrochromic device in Example 1 after 5000 cycles at 660 nm.

[0018] Figure 3 The transmittance diagram and color change effect diagram of the integrated electrochromic device in Example 2 in the full band of 400~800nm.

[0019] Figure 4 This is a transmittance test chart of the integrated electrochromic device in Example 3 at different peak voltages.

[0020] Figure 5 These are the coloring and fading effect diagrams of the integrated electrochromic device in Comparative Example 1, wherein a is a schematic diagram of the initial electrochromic device, b is a schematic diagram of the electrochromic device being colored when a voltage of -3V is applied, c is a schematic diagram of the electrochromic device being faded when a voltage of 1V is applied, and d is a schematic diagram of the electrochromic device being colored when a voltage of -3V is applied again. DETAILED DESCRIPTION

[0021] Example 1 A kind of silicon dioxide and P2W 18 Integrated electrochromic device based on composite gel

[0022] (1) Preparation method

[0023] 1) Preparation of silica gel: Weigh 3.0 g of sodium silicate and dissolve it in 20 mL of deionized water. Stir at room temperature at 500 rpm to dissolve the mixture. Once completely dissolved, slowly add 5 mL of concentrated hydrochloric acid dropwise while stirring to obtain a translucent silica gel. Age the silica gel at room temperature for 20 h. Wash the aged silica gel 2–3 times with deionized water and filter it for later use.

[0024] 2) Preparation of color-changing gel: 1.5 g of P2W 18 Dissolve in 5 mL of deionized water. Once completely dissolved, add 1 mL to the silica gel prepared in step 1). Stir at room temperature for 10 minutes at 500 rpm until uniform. Dissolve 1.0 g of lithium bis(trifluoromethanesulfonyl)imide in 5 mL of propylene carbonate. Add 1 mL to the mixture. Stir at room temperature for 10 minutes at 500 rpm until uniform. Dissolve 0.24 g of lithium iodide in 1 mL of deionized water. Add 1 mL to the mixture. Stir at room temperature for 2 hours at 500 rpm to obtain a color-changing gel. Ultrasonicate for 30 minutes and set aside.

[0025] 3) Assembly of the integrated electrochromic device: Cut a 1.5*2 cm tape frame. Take two cleaned FTO glass sheets and attach the tape frame to the conductive surface of one of them. Pour the color-changing gel onto the tape frame. Take the other FTO glass sheet and cover it with the color-changing gel. Press firmly to remove any bubbles to complete the integrated electrochromic device.

[0026] (2) Performance testing

[0027] The prepared device was subjected to a long cycle test using an electrochemical workstation and a UV spectrophotometer. A voltage of -3 V was applied for 10 seconds to colorize and a voltage of 1 V was applied for 15 seconds to fade. The wavelength was 660 nm. The transmittance of the device changed as shown in the following figure. Figure 2As shown, the transmittance ΔT is 83%, and it hardly decreases after 5000 cycles.

[0028] Example 2 A kind of silicon dioxide and PW 12 Integrated electrochromic device based on composite gel

[0029] (1) Preparation method

[0030] 1) Preparation of silica gel: Weigh 3.0 g of sodium silicate and dissolve it in 20 mL of deionized water. Stir at room temperature at 500 rpm to dissolve the mixture. Once completely dissolved, slowly add 5 mL of concentrated hydrochloric acid dropwise while stirring to obtain a translucent silica gel. Age the silica gel at room temperature for 22 hours. Wash the aged silica gel 2–3 times with deionized water and filter it for later use.

[0031] 2) Preparation of color-changing gel: 3.5 g of PW 12 Dissolve in 5 mL of deionized water. Once completely dissolved, add 1 mL to the silica gel prepared in step 1). Stir at room temperature for 15 minutes at 500 rpm until uniform. Dissolve 1.0 g of tetramethylammonium hexafluorophosphate in 5 mL of propylene carbonate. Add 1 mL to the mixture. Stir at room temperature for 15 minutes at 500 rpm until uniform. Dissolve 0.24 g of ferrocene in 1 mL of deionized water. Add 1 mL to the mixture. Stir at room temperature for 2.5 hours at 500 rpm to obtain a color-changing gel. Ultrasonicate for 30 minutes and set aside.

[0032] 3) Assembly of the integrated electrochromic device: Cut a 1.5*2 cm tape frame. Take two cleaned FTO glass sheets and attach the tape frame to the conductive surface of one of them. Pour the color-changing gel onto the tape frame. Take the other FTO glass sheet and cover it with the color-changing gel. Press firmly to remove any bubbles to complete the integrated electrochromic device.

[0033] (2) Performance testing

[0034] The prepared device was subjected to full spectrum testing using an electrochemical workstation coupled with an ultraviolet spectrophotometer with a scanning range of 400-800 nm. Figure 3 As shown, the maximum absorption wavelength (λ max ) is 660nm, at this time ΔT=95%.

[0035] Example 3 An integrated electrochromic device of silicon dioxide and phosphomolybdic acid composite gel

[0036] (1) Preparation method

[0037] 1) Preparation of silica gel: Weigh 3.0 g of sodium silicate and dissolve it in 20 mL of deionized water. Stir at room temperature at 500 rpm to dissolve the mixture. Once completely dissolved, slowly add 5 mL of concentrated hydrochloric acid dropwise while stirring to obtain a translucent silica gel. Age the silica gel at room temperature for 24 hours. Wash the aged silica gel 2–3 times with deionized water and filter it for later use.

[0038] 2) Preparation of color-changing gel: Dissolve 2.0g of phosphomolybdic acid in 5mL of deionized water. Once completely dissolved, add 1mL to the silica gel prepared in step 1). Stir at room temperature for 20 minutes at 500 rpm until uniform. Dissolve 1.0g of lithium bis(trifluoromethanesulfonyl)imide in 5mL of propylene carbonate. Add 1mL to the mixture. Stir at room temperature for 20 minutes at 500 rpm until uniform. Dissolve 0.20g of tetramethylthiourea in 1mL of deionized water. Add 1mL to the mixture. Stir at room temperature for 3 hours at 500 rpm. Ultrasonicate for 30 minutes to obtain the color-changing gel. Set aside.

[0039] 3) Assembly of the integrated electrochromic device: Cut a 1.5*2cm tape frame. Take two cleaned ITO glass sheets and attach the tape frame to the conductive surface of one of them. Pour the color-changing gel onto the tape frame. Take the other ITO glass sheet and cover it with the color-changing gel. Press firmly to remove any bubbles to complete the integrated electrochromic device.

[0040] (2) Performance testing

[0041] The transmittance of the prepared device was tested at different peak voltages using an electrochemical workstation and a UV spectrophotometer. Figure 4 At a wavelength of 660nm, the device was tested with tinting voltages of -1.9V, -2.2V, and -2.8V for 600s and fading voltages of 1V for 10s. The device maintained the same transmittance for a long time at the same tinting voltage, and faded normally when the fading voltage was applied.

[0042] Comparative Example 1

[0043] (1) Preparation method

[0044] The only difference from Example 1 is that silica gel is not added. Other aspects are the same as Example 1.

[0045] 1) Preparation of color-changing gel: 1.5 g of P2W 18 Dissolve in 5 mL of deionized water, and take 1 mL of P2W after complete dissolution 18 Then take 1.0g of tetramethylammonium hexafluorophosphate and dissolve it in 5mL of propylene carbonate. Take 1mL and add 1mL of P2W 18The solution was stirred at room temperature for 10 minutes at a speed of 500 r / min until uniform. 0.24 g of lithium iodide was dissolved in 1 mL of deionized water, and 1 mL was added to the above mixture. The mixture was stirred at room temperature for 2 hours at a speed of 500 r / min to obtain a color-changing gel, which was then ultrasonicated for 30 minutes for use.

[0046] 2) Assembly of the integrated electrochromic device: Cut a 1.5*2 cm tape frame. Take two cleaned FTO glass sheets and attach the tape frame to the conductive surface of one of them. Pour the color-changing gel onto the tape frame. Take the other FTO glass sheet and cover it with the color-changing gel. Press firmly to remove any bubbles to complete the integrated electrochromic device.

[0047] (2) Performance testing

[0048] The prepared device was colored by applying -3V voltage for 10s and faded by applying 1V voltage for 15s using an electrochemical workstation. The transmittance color change effect of the device is shown in Figure 2. Figure 5 As shown, the device colored and faded normally. When it was colored again, a large number of small bubbles were found inside the device, and the device was damaged after 10 cycles.

[0049] PW used in the examples 12 The analytically pure reagent phosphotungstic acid hydrate (CAS No.: 12501-23-4) was purchased directly and used directly without further purification. The phosphomolybdic acid used was the analytically pure reagent phosphomolybdic acid hydrate (CAS No.: 51429-74-4) purchased directly and used directly without further purification.

[0050] P2W used in the examples and comparative examples 18 The synthesis method is as follows:

[0051] At room temperature, a sample of Na2WO4·2H2O (analytical grade, 260g; 0.79mol) was dissolved in 300mL of deionized water. 200mL of 4mol / L HCl was slowly added to the Na2WO4 solution and stirred until the mixture became clear from turbidity. Then, 200mL of 4M H3PO4 was added. The resulting pale yellow solution was refluxed at 150°C for 24 hours. After reflux, the solution was cooled to room temperature and 150g of KCl was added. The resulting precipitate was the target product, which was filtered and dried to obtain P2W. 18 Crude product. 18 The crude product was dissolved in 500 mL of boiling deionized water and filtered to remove insoluble impurities while hot. The filtrate was placed in a 500 mL beaker and cooled to room temperature and then placed in a refrigerator at 4 ° C. After 24 hours, pure P2W was obtained at the bottom of the beaker. 18 Yellow crystals, filtered to obtain crystals P2W18 After drying at room temperature, the P2W used in the present invention is obtained. 18 (Yield 147g).

Claims

1. An integrated electrochromic device of silica gel, characterized in that: The structure of the integrated electrochromic device is divided into three layers: a transparent conductive substrate, a color-changing gel, and a transparent conductive substrate. The color-changing gel is sandwiched between two transparent conductive substrates. The color-changing gel is a mixture of silica gel, metal oxygen clusters, redox equilibrium species and ionic liquid solution. The metal oxygen clusters are PW 12 、P2W 18 or phosphomolybdic acid, and the redox equilibrium species are lithium iodide, ferrocene, or tetramethylthiourea.

2. The integrated electrochromic device of silica gel according to claim 1, characterized in that: The transparent conductive substrate is FTO conductive glass or ITO conductive glass.

3. The integrated electrochromic device of silica gel according to claim 1, characterized in that: The ionic liquid solution is a lithium bis(trifluoromethanesulfonyl)imide propylene carbonate solution or a tetramethylammonium hexafluorophosphate propylene carbonate solution.

4. The method for preparing a silica gel integrated electrochromic device according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1) Preparation of silica gel: Add 3.0 g of sodium silicate to deionized water and dissolve by stirring at room temperature at 500 r / min. Once completely dissolved, add 5 mL of concentrated hydrochloric acid while stirring to form a translucent silica gel. Allow to age at room temperature for 20-24 h to obtain the silica gel. 2) Preparation of color-changing gel: Silica gel, metal oxygen cluster solution, ionic liquid solution, and redox equilibrium species solution are mixed uniformly to form a color-changing gel; 3) The color-changing gel is sandwiched between two transparent conductive substrates to assemble an integrated electrochromic device.

5. The preparation method according to claim 4, characterized in that Step 2) The specific steps are as follows: add 1 mL of metal oxide cluster solution to silica gel, stir at room temperature for 10-20 minutes at a speed of 500 r / min; then add 1 mL of ionic liquid solution to the mixed system, stir at room temperature for 10-20 minutes at a speed of 500 r / min; then add 1 mL of redox balance species solution to the mixed system, stir at room temperature for 2-3 hours at a speed of 500 r / min to obtain a color-changing gel, and then ultrasonicate the color-changing gel for 30 minutes.

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