An all-in-one electrochromic device of silica gel and a preparation method thereof

Abstract

The application belongs to the technical field of electrochromic devices, and particularly relates to a one-piece electrochromic device of silica gel and a preparation method thereof. The one-piece electrochromic device has a three-layer structure, which is a transparent conductive substrate, a color-changing gel and a transparent conductive substrate. The color-changing gel is a composite gel of silica gel and a metal oxygen cluster material, and by adding a suitable redox balancing species and an ionic liquid, the one-piece electrochromic device with high optical contrast and super-long cycle stability is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochromic devices, and particularly relates to a silica gel integrated electrochromic device and a preparation method thereof. BACKGROUND

[0002] Traditional electrochromic devices are mostly five-layer sandwich structures, namely, transparent conductive electrode 1, electrochromic layer, electrolyte layer, ion storage layer, and transparent conductive electrode 2, which has a very complex structure and a tedious preparation process. Existing integrated electrochromic devices are mostly organic color-changing species, such as viologen and its derivatives combined with organic gel. Organic substances will cause a decrease in stability when exposed to ultraviolet light for a long time. Metal oxo clusters, as inorganic color-changing materials, have good solubility in water, excellent redox performance, and good ultraviolet stability, and have received extensive attention in the field of electrochromism. Silica gel has high transparency, good dispersibility, and adsorption, and can be used as an excellent carrier material. The combination of metal oxo clusters and silica gel is expected to integrate the advantages of both and prepare an integrated electrochromic gel to improve the electrochromic performance of metal oxo clusters and increase the practical application value. SUMMARY

[0003] The purpose of the present application is to provide a silica gel integrated electrochromic device and a preparation method thereof, which has good electrochromic performance and super-long cycle stability.

[0004] The technical solution adopted by the present application is as follows:

[0005] The structure of the silica gel integrated electrochromic device comprises three layers, namely, transparent conductive substrate, color-changing gel, and transparent conductive substrate, and the color-changing gel is sandwiched between the two transparent conductive substrates; the color-changing gel is a mixture of silica gel, metal oxo clusters, redox balancing species, and ionic liquid solution; the metal oxo clusters are PW 12 , P2W 18 , or phosphomolybdic acid, and the redox balancing species are lithium iodide, ferrocene, or tetramethyl thiourea.

[0006] Further, the silica gel integrated electrochromic device has the transparent conductive substrate being FTO conductive glass or ITO conductive glass.

[0007] Further, the silica gel integrated electrochromic device has the ionic liquid solution being a lithium bis-trifluoromethanesulfonimide propylene carbonate solution or a tetramethylammonium hexafluorophosphate propylene carbonate solution.

[0008] The preparation method of the silica gel integrated electrochromic device comprises the following steps:

[0009] 1) Preparation of silica gel: 3.0 g of sodium silicate is added to deionized water, dissolved at room temperature with stirring at a speed of 500 r / min, and after complete dissolution, 5 mL of concentrated hydrochloric acid is added to form a translucent silica gel, which is aged at room temperature for 20-24 h to obtain a silica gel;

[0010] 2) Preparation of color-changing gel: the silica gel, metal oxo-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] Further, the preparation method described above, the specific steps of step 2) are: 1 mL of metal oxo-cluster solution is added to the silica gel, stirred at room temperature for 10-20 min at a speed of 500 r / min; then 1 mL of ionic liquid solution is continuously added to the mixed system, stirred at room temperature for 10-20 min at a speed of 500 r / min; then 1 mL of redox equilibrium species solution is continuously added to the mixed system, stirred at room temperature for 2-3 h at a speed of 500 r / min, to obtain a color-changing gel, and the color-changing gel is ultrasonically treated for 30 min.

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

[0014] 1) The present application uses high-transparency silica gel as the gel skeleton of the integrated electrochromic material, mixes metal oxo-clusters with the gel, and simplifies the structure of the electrochromic device. By selecting a suitable redox balancing material, the coloring and bleaching capabilities of the device are enhanced. An integrated electrochromic device with ultra-long cycle stability is obtained.

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

[0016] Figure 1 It is a structural schematic diagram of the integrated electrochromic device of the present application.

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

[0018] Figure 3 It is a transmittance graph and a color-changing effect graph of the integrated electrochromic device in Example 2 in the full wave band of 400-800 nm.

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

[0020] Figure 5 Coloring and bleaching effect diagram of the one-piece electrochromic device in Comparative Example 1, wherein a is a schematic diagram of an initial electrochromic device, b is a schematic diagram of the electrochromic device coloring under the application of a voltage of -3V, c is an effect diagram of the electrochromic device bleaching under the application of a voltage of 1V, and d is a schematic diagram of the electrochromic device coloring again under the application of a voltage of -3V. DETAILED DESCRIPTION

[0021] Example 1 A silicon dioxide and P2W 18 One-piece electrochromic device of composite gel

[0022] (I) Preparation method

[0023] 1) Preparation of a silicon dioxide gel: 3.0 g of sodium silicate was dissolved in 20 mL of deionized water, and stirred at room temperature at a speed of 500 r / min. After complete dissolution, 5 mL of concentrated hydrochloric acid was slowly added dropwise while stirring, to obtain a translucent silicon dioxide gel. The silicon dioxide gel was placed at room temperature for 20 h of aging. The aged silicon dioxide gel was washed with deionized water for 2-3 times, and was ready for use after filtration.

[0024] 2) Preparation of a color-changing gel: 1.5 g of P2W 18 was dissolved in 5 mL of deionized water, and 1 mL of the solution was added to the silicon dioxide gel prepared in step 1) after complete dissolution. The mixture was stirred at room temperature at a speed of 500 r / min for 10 min. Then, 1.0 g of lithium bis-trifluoromethanesulfonimide was dissolved in 5 mL of propylene carbonate, and 1 mL of the solution was added to the above mixture. The mixture was stirred at room temperature at a speed of 500 r / min for 10 min. Then, 0.24 g of lithium iodide was dissolved in 1 mL of deionized water, and 1 mL of the solution was added to the above mixture. The mixture was stirred at room temperature at a speed of 500 r / min for 2 h, and was ready for use after ultrasonic treatment for 30 min.

[0025] 3) Assembly of a one-piece electrochromic device: a 1.5*2 cm adhesive tape frame was cut, two cleaned FTO glasses were taken, and the adhesive tape frame was attached to the conductive surface of one of the FTO glasses. The color-changing gel was poured into the adhesive tape frame, and the other FTO glass was placed on the color-changing gel and pressed to remove air bubbles, to obtain a one-piece electrochromic device.

[0026] (II) Performance test

[0027] The prepared device was subjected to long cycle test, and was tested by using an electrochemical workstation and a UV spectrophotometer in combination. A voltage of -3V was applied for 10 s for coloring, and a voltage of 1V was applied for 15 s for bleaching. The wavelength was 660 nm, and the transmittance change of the device was as shown in 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: 3.0 g of sodium silicate was dissolved in 20 mL of deionized water, stirred at room temperature, the stirring speed was 500 r / min, after complete dissolution, 5 mL of concentrated hydrochloric acid was slowly added dropwise while stirring, a translucent silica gel was obtained, the silica gel was placed at room temperature for 24 h aging. The aged silica gel was washed with deionized water for 2-3 times, and was ready for use after filtration.

[0038] 2) Preparation of color-changing gel: 2.0 g of phosphomolybdic acid was dissolved in 5 mL of deionized water, 1 mL of the solution was added to the silica gel prepared in step 1), and stirred at room temperature for 20 min, the stirring speed was 500 r / min. Then 1.0 g of lithium bistrifluoromethanesulfonimide was dissolved in 5 mL of propylene carbonate, 1 mL of the solution was added to the above mixture, and stirred at room temperature for 20 min, the stirring speed was 500 r / min. Then 0.20 g of tetramethylthiourea was dissolved in 1 mL of deionized water, 1 mL of the solution was added to the above mixture, and stirred at room temperature for 3 h, the stirring speed was 500 r / min. The color-changing gel was obtained after ultrasonic treatment for 30 min and was ready for use.

[0039] 3) Assembly of integrated electrochromic device: a 1.5*2 cm adhesive tape frame was cut, two cleaned ITO glasses were taken, the adhesive tape frame was attached to the conductive surface of one of the ITO glasses, the color-changing gel was poured into the adhesive tape frame, the other ITO glass was taken and covered on the color-changing gel, and was pressed to remove air bubbles to obtain an integrated electrochromic device.

[0040] (B) Performance test

[0041] The prepared device was tested for transmittance at different peak voltages, and an electrochemical workstation and an ultraviolet spectrophotometer were used. For example Figure 4 , the coloring was carried out at a wavelength of 660 nm and a coloring voltage of -1.9 v, -2.2 v, -2.8 v / 600 s, and the bleaching was carried out at 1 v / 10 s. The device could maintain the same transmittance for a long time at the same coloring voltage, and the device could normally bleach at the given bleaching voltage.

[0042] Comparative Example 1

[0043] (A) Preparation method

[0044] The difference from Example 1 is only that no silica gel is added. The others are the same as Example 1.

[0045] 1) Preparation of color-changing gel: 1.5 g of P2W 18 was dissolved in 5 mL of deionized water, 1 mL of the P2W 18 solution was taken. Then 1.0 g of tetramethylammonium hexafluorophosphate was dissolved in 5 mL of propylene carbonate, 1 mL of the solution was added to 1 mL of the P2W 18In the solution, stirring at room temperature for 10 min, 500 r / min, stirring evenly. Take 0.24 g of lithium iodide dissolved in 1 mL of deionized water, take 1 mL into the above mixed system, stirring at room temperature for 2 h, 500 r / min, get color change gel ultrasonic 30 min after standby.

[0046] 2) Assembly of integrated electrochromic device: cut 1.5*2 cm of adhesive tape frame, take two pieces of clean FTO glass, paste the adhesive tape frame on the conductive surface of one of them, pour the color-changing gel into the adhesive tape frame, take another piece of FTO glass, cover it on the color-changing gel, press hard to remove bubbles to get an integrated electrochromic device.

[0047] (II) Performance test

[0048] The prepared device was applied with-3V voltage for 10s for coloring, and 1V voltage for 15s for decoloring. The transmittance color change effect of the device is shown in Figure 5 The device coloring is normal, and the decoloring is normal. When coloring again, a large number of small bubbles are found in the device, and the device is damaged after 10 cycles.

[0049] PW used in the examples 12 It is an analytical reagent purchased directly, and no further purification treatment is made. The phosphomolybdic acid used is an analytical reagent purchased directly (CAS number: 51429-74-4), and no further purification treatment is made.

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

[0051] At room temperature, Na2WO4·2H2O (analytical pure, 260 g; 0.79 mol) sample was dissolved in 300 mL of deionized water, and 200 mL of 4 mol / L HCl aqueous solution was slowly added to the Na2WO4 aqueous solution and stirred evenly. After the mixture changed from turbidity to clarity, 200 mL of 4M H3PO4 aqueous solution was added. The light yellow solution obtained was refluxed at 150℃ for 24 hours. After the reflux was completed, the solution was cooled to room temperature, and then 150 g of KCl was added. The obtained precipitate was the target product, which was filtered and dried to obtain P2W 18 crude product. P2W 18 crude product was dissolved in 500 mL of boiling deionized water, and the insoluble impurities were removed by hot filtration. The filtrate was placed in a 500 mL beaker and cooled to room temperature, and then placed in a refrigerator at 4℃. After 24 hours, pure P2W 18 yellow crystals, the crystal P2W was obtained by filtration18 P2W used in the present application was obtained after drying at room temperature 18 (yield 147 g).

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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