A high strength gel-based flexible electrochromic device

Abstract

The present application relates to a kind of high-strength gel-based flexible electrochromic device.The high-strength gel-based flexible electrochromic device includes the first flexible electrode, electrochromic layer, gel electrolyte layer and second flexible electrode arranged in sequence;The gel electrolyte layer includes host material and cationic salt distributed in host material, and the host material is amino-terminated polyimide resin;Preferably, the molar ratio of cationic salt and amino-terminated polyimide resin is (2%~5%):1.

Description

Technical Field

[0001] This invention relates to a high-strength gel-based flexible electrochromic device, belonging to the field of chemical material synthesis and functional material technology. Background Technology

[0002] Energy is a crucial foundation for maintaining a nation's sustained economic development and ensuring people's material well-being. Today, energy shortages and environmental pollution are increasingly severe, prompting scientists to develop new energy sources while simultaneously seeking methods to conserve energy and reduce consumption. Electrochromic devices and technologies are primarily applied in energy-efficient building glass, vehicle windows, anti-glare rearview mirrors, displays, electronic paper, and camouflage applications. Low-E glass is a type of low-emissivity glass that works by reflecting most infrared radiation, reducing heat entering the room. Insulating glass reduces heat exchange between the indoor and outdoor spaces. Both aim to reduce indoor cooling energy consumption. However, these two types of windows, and their combinations, only facilitate cooling, not temperature regulation. That is, in cold winters, heat still struggles to enter the room.

[0003] Traditional electrochromic devices mainly consist of five thin films: two transparent conductive layers, an ion storage layer, an electrochromic layer, and an ion conduction layer. The ion storage layer assists the electrochromic layer in achieving the electrochromic reaction by applying a low voltage to the first and second conductive layers. The ion conduction layer provides lithium ions and diffuses the thin film, ensuring ion conductivity under an electric field. Its structure and fabrication process are among the most important technologies for guaranteeing the electrochromic performance of the device.

[0004] Electrochromic devices can be classified into three types based on the state of the ion-conducting layer: liquid electrochromic devices, gel electrochromic devices, and all-solid-state electrochromic devices. Liquid electrochromic devices exhibit low resistance during ion migration, high ion conductivity, fast electrochromic speed, and high transparency, and are simple to prepare and easy to fill; however, they suffer from problems such as leakage, corrosion, and uneven distribution, requiring extremely high and precise filling and sealing techniques. With repeated cycles of the electrochromic reaction, the ion concentration of the electrolyte tends to become unstable, causing a significant deterioration in the performance of the electrochromic device; the H+ in acidic electrolytes... +Ions corrode electrochromic thin film materials, which is detrimental to long-term use. Furthermore, organic electrolytes have poor safety; for example, LiClO4 is prone to explosion and unsuitable for long-term storage and transportation. Organic solvents are also susceptible to high temperatures and have poor chemical stability, leading to uneven device coloring. Gel-based electrochromic devices utilize a gel-like ion-conducting layer formed by incorporating certain conductive polymers into a liquid ion-conducting layer. This gel-like (quasi-solid-state) ion-conducting layer lies between solid and liquid states, exhibiting higher ionic conductivity than liquid electrolytes. It possesses excellent flexibility and adhesion, reducing damage from splashes of hard materials like glass when the device is subjected to external force. However, its mechanical strength and uniformity are poor, failing to meet the requirements for large-scale industrial production. All-solid-state electrochromic devices offer structural stability and good resistance to water, oxygen, and ultraviolet radiation, avoiding the shortcomings of liquid and quasi-solid-state devices.

[0005] Furthermore, current all-solid-state electrochromic devices based on rigid substrates suffer from high cost, transportation difficulties, limited applications, and production capacity constraints. Flexible electrochromic devices, due to their unique characteristics, can effectively avoid these problems. However, flexible devices face the issue of interface delamination during flexible bending. Therefore, improving interfacial adhesion is a key issue in obtaining high-performance flexible devices. The flexible electrolyte layer in existing flexible electrochromic devices has poor bending resistance, is prone to interface separation during bending cycles, and the resin itself is susceptible to cracking, resulting in a significant reduction in the electrochromic performance of the device. Summary of the Invention

[0006] Existing flexible electrochromic devices suffer from poor performance, such as interface detachment during bending or cutting, or electrolyte leakage, which limits their application and promotion. This invention provides a high-strength gel-based flexible electrochromic device, comprising a first flexible electrode, an electrochromic layer, a gel electrolyte layer, and a second flexible electrode stacked sequentially. The gel electrolyte layer comprises a host material and a cationic salt distributed within the host material. The host material is an amino-terminated polyimide resin. Preferably, the molar ratio of the cationic salt to the amino-terminated polyimide resin is (2%-5%):1.

[0007] In this disclosure, by enhancing the intrinsic strength of the resin layer and the angle of its bonding force with the upper and lower film layers, the cycling stability of the device is significantly improved, resulting in a high-strength gel-based flexible electrochromic device.

[0008] Specifically, by selecting amino-terminated polyimide resins with extended polyimide chain lengths as the host material, not only is the resin strength increased, but the number of amide bonds and coordination sites is also increased, further enhancing its interfacial bonding with the electrode. Moreover, amino-terminated polyimide resins not only serve as the host material for the electrolyte layer, enabling efficient cation migration, but also, due to their excellent binding force, can tightly bind the upper and lower flexible electrodes.

[0009] Preferably, the cation salt is selected from at least one of sodium salt, lithium salt, magnesium salt and aluminum salt, and more preferably from at least one of lithium perchlorate, sodium perchlorate, magnesium perchlorate, magnesium chloride, sodium chloride and lithium chloride.

[0010] Preferably, the thickness of the gel electrolyte layer is 10–100 μm.

[0011] Preferably, the first flexible electrode comprises a flexible conductive substrate and a conductive material formed on the surface of the flexible conductive substrate; the flexible conductive substrate is at least one selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene, polyethylene, and polyvinyl chloride, and the conductive material is selected from at least one selected from transparent conductive oxides and metal nanowires; preferably, the surface sheet resistance of the first flexible electrode is 10–40 Ω / cm. 2 Transmittance ≥75%.

[0012] Preferably, the second flexible electrode comprises a flexible conductive substrate and a conductive material formed on the surface of the flexible conductive substrate; the flexible conductive substrate is at least one selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene, polyethylene, and polyvinyl chloride, and the conductive material is selected from at least one selected from transparent conductive oxides and metal nanowires; preferably, the surface sheet resistance of the second flexible electrode is 10–40 Ω / cm. 2 Transmittance ≥75%.

[0013] Preferably, the electrochromic layer is made of at least one of inorganic oxides, PEDOT, polyaniline, and viologen, wherein the inorganic oxide is selected from WO3. 3-x (0<x≤0.3, preferably 0.02≤x≤0.3), at least one of V2O5, MoO3, Bruce Blue and TiO2; the thickness of the electrochromic layer is 100~500nm.

[0014] Preferably, the method for preparing the gel electrolyte layer includes:

[0015] (1) Dissolve the cationic salt in an organic solvent to obtain a cationic salt solution;

[0016] (2) After adding the dianhydride monomer and the diamine monomer to the cationic salt solution and mixing them, an amino-terminated polyamic acid solution is obtained;

[0017] (3) Add crosslinking agent, dehydrating agent and catalyst to amino-terminated polyamic acid solution and mix to obtain mixed solution;

[0018] (4) The mixed solution is coated onto the substrate and left to stand at 30-80°C for 10 min-2 h to obtain the gel electrolyte layer.

[0019] Furthermore, preferably, the solvent is at least one selected from propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and dimethyl glycol ether (DME); and the concentration of the cation salt solution is 0.5–2 mol / L.

[0020] Furthermore, preferably, the total mass ratio of the dianhydride monomer and the diamine monomer to the cationic salt solution is 1:(5-20); the molar ratio between the dianhydride monomer and the diamine monomer is n:(n+1), where n≥500.

[0021] Furthermore, preferably, the dianhydride monomer is selected from one of pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and diphenyl ether tetracarboxylic dianhydride, and the diamine monomer is selected from at least one of hexylene diamine, decylene diamine, diaminodiphenylmethane, diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, m-toluene diamine, and diaminodiphenyl sulfone.

[0022] Furthermore, preferably, the crosslinking agent is selected from at least one of triglycidyl-p-aminophenol, triglycidyl-triisocyanate, tetraglycidyl-diaminodiphenylmethane, tetraglycidyl-diphenyldiamine, and pyromellitic acid chloride, and the amount added is 1% to 5% of the total mass of the amino-terminated polyamic acid solution. In addition, using epoxy resin as a crosslinking agent improves the molecular cohesion of the film layer, further enhancing the strength of the resin.

[0023] Furthermore, preferably, the dehydrating agent is selected from at least one of acetic anhydride, propionic anhydride, valeric anhydride, and dimethyl ketone, and the amount added is 0.5% to 5% of the total mass of the amino-terminated polyamic acid solution.

[0024] Furthermore, preferably, the catalyst is selected from at least one of pyridine, 4-methylpyridine, 3,4-dimethylpyridine, isoquinoline and triethylamine, and is added in an amount of 0.1% to 1% of the total mass of the amino-terminated polyamic acid solution.

[0025] Preferably, the high-strength gel-based flexible electrochromic device exhibits less than 10% degradation in electrochromic performance after 1000 consecutive bending cycles.

[0026] The beneficial effects of this invention are:

[0027] 1. This invention designs a flexible electrochromic device with a sandwich structure, using high-strength polyimide as the main material for the interlayer electrolyte. Therefore, the prepared flexible electrochromic device exhibits good interfacial bonding. By optimizing the electrolyte material and composition, ion migration efficiency is improved, thereby enhancing the performance of the flexible electrochromic device.

[0028] 2. The preparation process of each film layer in this invention is simple and does not require the addition of complex equipment or harsh processing conditions;

[0029] 3. This invention increases the resin strength and the number of amide bonds by extending the chain length of the polyimide, thereby increasing the number of coordination sites and further enhancing its interfacial bonding with the electrode. Furthermore, the use of epoxy resin as a crosslinking agent improves the molecular cohesion of the film layer, further enhancing the resin strength. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the gel-based flexible electrochromic device of the present invention;

[0031] Figure 2 The cycling performance of the gel-based flexible electrochromic device in Example 1 after 1000 cycles is shown. Detailed Implementation

[0032] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0033] In this field, compared with all-solid-state electrochromic devices, flexible electrochromic devices have significant advantages such as light weight, customizability, and wide application range. However, flexible devices often face the risk of leakage or interface detachment during bending or cutting. To address this, the present invention provides a high-strength gel-based flexible electrochromic device, comprising a first flexible electrode, an electrochromic layer, a gel electrolyte layer, and a second flexible electrode stacked sequentially. The gel electrolyte layer is composed primarily of amino-terminated polyimide and a cationic salt as the solute. By controlling the degree of polymerization of the monomers in the amino-terminated polyimide, the intramolecular cohesion and coordination number are increased, synergistically enhancing the resin strength and ion migration ability. Preferably, the thickness of the gel electrolyte layer is 10-100 μm. Preferably, the gel electrolyte layer is a cationic conductive layer based on an organic resin, wherein the cationic cation is Mg. 2+ H + Al 3+ Li + and Na + At least one of them.

[0034] Specifically, this invention discloses a method for preparing high-strength amino-terminated polyimide resin at room temperature and using it as the main material for the electrolyte layer in flexible electrochromic devices. This amino-terminated polyimide resin not only serves as the main material for the electrolyte layer, enabling efficient cation migration, but also possesses excellent binding strength, allowing it to tightly bind the upper and lower flexible electrodes.

[0035] The electrochromic layer is made of at least one of inorganic oxides such as WO3, V2O5, MoO3, Bruce Blue, and TiO2, or organic compounds such as PEDOT, polyaniline, and viologen. The thickness of the electrochromic layer can be 100–500 nm.

[0036] In addition to the flexible conductive substrate, the materials of the first flexible electrode and the second transparent flexible electrode are each independently selected from at least one of transparent conductive oxide and metal nanowires. The sheet resistance of the first flexible electrode and the second flexible electrode can be 10–40 Ω / cm. 2 Transmittance ≥75%.

[0037] In optional embodiments, the electrochromic layer can be prepared by methods such as magnetron sputtering, laser pulse deposition, molecular beam epitaxy, spin coating, spraying, or dip coating.

[0038] The DC magnetron sputtering system used in this invention for magnetron sputtering deposition may include a deposition chamber, a sample inlet chamber, several target heads, a substrate, a DC current source, and a series of mechanical pumps and vacuum pumps. The target heads are at a certain angle to the substrate and separated by a certain distance. The DC power supply is connected to the target heads. The substrate is ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 20 minutes each, and then dried with compressed air. A portion of the conductive substrate is covered with high-temperature tape as an electrode and fixed to the substrate tray. The substrate is placed in the sample inlet chamber, and the mechanical pump is turned on to evacuate to below 5 Pa. Then, the baffle valve is opened, and the vacuum level (baseline vacuum) reaches 10. -4 Splash chambers with Pa and below.

[0039] An inorganic electrochromic layer is continuously deposited on the surface of a first flexible electrode as a substrate. The target material is tungsten, molybdenum, vanadium, or titanium, and the sputtering gas is argon and oxygen. The total pressure is 0.5–2.0 Pa, the oxygen partial pressure is 0–50%, the distance between the target and the substrate is 10–20 cm, the initial substrate temperature is room temperature, and the DC power applied to the target is 30–150 W or the power density is 0.6–3.0 W / cm². 2 Finally, an electrochromic layer film with a thickness of 100 nm to 500 nm was deposited.

[0040] A cationic salt solution with a concentration of 0.5–2 mol / L (e.g., 1 mol / L) is prepared. The solvent is propylene carbonate. The solute is at least one of lithium perchlorate, sodium perchlorate, magnesium perchlorate, magnesium chloride, sodium chloride, and lithium chloride.

[0041] The dianhydride monomer and diamine monomer are dissolved in a cationic salt solution and mixed (e.g., stirred for 10–50 minutes) to obtain a viscous polyamic acid solution (or an amino-terminated polyamic acid solution). The mass ratio of the total added monomer to the cationic salt solution is 1:(5–20). Adding too much monomer results in a low cationic content in the final resin, affecting the electrochromic properties of the device. Adding too little monomer affects the strength of the cured resin and reduces interfacial bonding. The molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n≥500, and the cationic salt solution is used. The molar ratio of the dianhydride monomer to the diamine monomer affects the final degree of polymerization and the chain length of the resin. A higher degree of polymerization results in a longer resin chain, leading to better strength. In this patent, when the molar ratio of the monomers is below 500, the resin strength is too low to meet the requirements of the flexible device designed in this patent.

[0042] A crosslinking agent, a dehydrating agent, and a catalyst are added sequentially to an amino-terminated polyamic acid solution, with a mass ratio controlled at 1:(1%–5%):(0.5%–5%):(0.1%–1%), and then mixed to obtain a mixed solution. The mixing method can be stirring for 2–20 minutes.

[0043] The mixed solution is coated onto a flexible conductive substrate and allowed to stand. Polymerization is then carried out at room temperature, followed by slow drying to obtain a polyimide PC gel, which serves as the gel dielectric layer. The standing temperature can be 30–80°C, and the time can be 10 min–2 h.

[0044] After the device has cured, an organic solvent is used to remove excess organic matter from the device surface. This completes the fabrication process for a high-strength gel-based flexible electrochromic device.

[0045] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0046] Example 1

[0047] (1) Using an ITO / PET flexible electrode as a substrate, the substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 20 min, respectively. It was then fixed to a substrate tray with high-temperature tape, placed in the sample injection chamber, and the mechanical pump was turned on to pump the sample to below 5 Pa. The baffle valve was then opened to introduce a vacuum (baseline vacuum) to reach 10. -4 Electrochromic layers were continuously deposited on the surface of a sputtering chamber with a pressure below Pa using magnetron sputtering. Tungsten was used as the target material, and the sputtering gases were argon and oxygen. The total pressure was 2.0 Pa, the oxygen partial pressure was 6%, the target-substrate distance was 15 cm, the initial substrate temperature was room temperature, and the applied DC power to the target was 70 W or the power density was 1.54 W / cm². 2 The deposition time was 30 min, and an inorganic electrochromic layer film with a thickness of about 350 nm was obtained.

[0048] (2) Prepare a 1 mol / L cationic salt solution, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Dissolve phenyltetracarboxylic dianhydride and hexanediamine in the cationic salt solution and stir for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of added monomer to cationic salt solution is 1:10, and the molar ratio of dianhydride monomer to diamine monomer is n:(n+1), n=500. Add triglycidyl-p-aminophenol, acetic anhydride and isoquinoline in the above amino-terminated polyamic acid solution in a ratio of 1:2%:1%:0.5% in sequence and stir for 10 minutes to obtain a mixed solution;

[0049] (3) The mixed solution was coated onto a flexible conductive substrate using a 20 μm wire rod and allowed to stand (50 °C for 1 h) to obtain a polyimide PC gel. After the device cured, ethyl acetate was used to remove excess organic matter from the device surface. This completes the fabrication process for a high-strength gel-based flexible electrochromic device. The basic structure of the device is as follows: Figure 1 As shown.

[0050] Example 2

[0051] The preparation process of the gel-based flexible electrochromic device in Example 2 is the same as in Example 1, except that in step (1), an ITO / PET flexible electrode is used as the substrate. The substrate is ultrasonically cleaned with acetone, ethanol and deionized water for 20 min respectively, then fixed on the substrate tray with high-temperature tape, placed in the sample injection chamber, and the mechanical pump is turned on to pump to below 5 Pa. The baffle valve is opened to introduce a vacuum degree (baseline vacuum degree) to reach 10. -4Electrochromic layers were continuously deposited on the surface of a sputtering chamber with a pressure below Pa using magnetron sputtering. Tungsten was used as the target material, and the sputtering gases were argon and oxygen. The total pressure was 2.0 Pa, the oxygen partial pressure was 6%, the target-substrate distance was 15 cm, the initial substrate temperature was room temperature, and the applied DC power to the target was 70 W or the power density was 1.54 W / cm². 2 The deposition time was 450 min, resulting in an inorganic electrochromic layer film with a thickness of about 500 nm.

[0052] Example 3

[0053] The preparation process of the gel-based flexible electrochromic device in Example 3 is the same as that in Example 1, except that in step (1), an ITO / PET flexible electrode is used as the substrate. The substrate is ultrasonically cleaned with acetone, ethanol and deionized water for 20 min respectively. Then, it is fixed on the substrate tray with high-temperature tape, placed in the sample injection chamber, and the mechanical pump is turned on to pump to below 5 Pa. The baffle valve is opened to introduce a vacuum degree (base vacuum degree) to reach 10. -4 Electrochromic layers were continuously deposited on the surface of a sputtering chamber with a pressure below Pa using magnetron sputtering. Tungsten was used as the target material, and the sputtering gases were argon and oxygen. The total pressure was 2.0 Pa, the oxygen partial pressure was 6%, the target-substrate distance was 15 cm, the initial substrate temperature was room temperature, and the applied DC power to the target was 70 W or the power density was 1.54 W / cm². 2 The deposition time was 10 min, and an inorganic electrochromic layer film with a thickness of about 100 nm was obtained.

[0054] Example 4

[0055] The preparation process of the gel-based flexible electrochromic device in Example 4 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 1000. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain the solution.

[0056] Example 5

[0057] The preparation process of the gel-based flexible electrochromic device in Example 5 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 10000. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0058] Example 6

[0059] The preparation process of the gel-based flexible electrochromic device in Example 6 is the same as in Example 1, except that in step (3), the mixed solution is coated onto a flexible conductive substrate using a 10 μm wire rod and left to stand (50°C and 1 h) to obtain a polyimide PC gel. After the device has cured, ethyl acetate is used to remove excess organic matter from the device surface.

[0060] Example 7

[0061] The preparation process of the gel-based flexible electrochromic device in Example 7 is the same as in Example 1, except that in step (3), the mixed solution is coated onto a flexible conductive substrate using a 100 μm wire rod and left to stand (50°C and 1 h) to obtain a polyimide PC gel. After the device has cured, ethyl acetate is used to remove excess organic matter from the device surface.

[0062] Example 8

[0063] The preparation process of the gel-based flexible electrochromic device in Example 8 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:5, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0064] Example 9

[0065] The preparation process of the gel-based flexible electrochromic device in Example 9 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:20, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0066] Example 10

[0067] The preparation process of the gel-based flexible electrochromic device in Example 10 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:1%:0.5%:0.1% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0068] Example 11

[0069] The preparation process of the gel-based flexible electrochromic device in Example 11 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:5%:5%:1% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0070] Example 12

[0071] The preparation process of the gel-based flexible electrochromic device in Example 12 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is sodium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0072] Example 13

[0073] The preparation process of the gel-based flexible electrochromic device in Example 13 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is aluminum perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 500. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a mixed solution.

[0074] Example 14

[0075] The preparation process of the gel-based flexible electrochromic device in Example 14 is the same as in Example 1, except that in step (3), the mixed solution is coated onto a flexible conductive substrate using a 20 μm wire rod and left to stand (80°C and 10 min) to obtain a polyimide PC gel. After the device has cured, ethyl acetate is used to remove excess organic matter from the device surface.

[0076] Example 15

[0077] The preparation process of the gel-based flexible electrochromic device in Example 15 is the same as in Example 1, except that in step (3), the solution is coated onto a flexible conductive substrate using a 20 μm wire and left to stand (30°C and 2 h) to obtain a polyimide PC gel. After the device has cured, ethyl acetate is used to remove excess organic matter from the device surface.

[0078] Example 16

[0079] The preparation process of the gel-based flexible electrochromic device in Example 16 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 2000. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain the solution.

[0080] Example 17

[0081] The preparation process of the gel-based flexible electrochromic device in Example 17 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 5000. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a solution.

[0082] Example 18

[0083] The preparation process of the gel-based flexible electrochromic device in Example 18 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 8000. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain the solution.

[0084] Comparative Example 1

[0085] The preparation process of the gel-based flexible electrochromic device in Comparative Example 1 is the same as in Example 1, except that in step (2), a 1 mol / L cationic salt solution is prepared, wherein the solvent is propylene carbonate and the solute is lithium perchlorate. Benzenetetracarboxylic dianhydride and hexanediamine are dissolved in the cationic salt solution and stirred for 30 minutes to obtain a viscous polyamic acid solution, wherein the mass ratio of the added monomer to the cationic salt solution is 1:10, and the molar ratio of the dianhydride monomer to the diamine monomer is n:(n+1), where n = 400. Triglycidyl-p-aminophenol, acetic anhydride, and isoquinoline are added sequentially in a ratio of 1:2%:1%:0.5% to the above amino-terminated polyamic acid solution and stirred for 10 minutes to obtain a solution.

[0086] In this invention, the bending test method for flexible electrochromic devices is as follows: A 5×3cm... 2 The two short sides of the flexible device are clamped simultaneously, and then both ends are moved towards the middle at the same time, with each movement distance being 2cm. Each bending and flattening constitutes one cycle. Bending performance refers to the ratio of the adjustment range after 1000 bending cycles to the initial value.

[0087] Table 1 shows the fabrication parameters of the gel-based flexible electrochromic device:

[0088]

[0089]

[0090] Table 1 shows the performance parameters of the gel-based flexible electrochromic device:

[0091]

[0092]

[0093] Electrochromic performance retention after bending cycles: response speed, adjustment range, and cycle stability.

Claims

1. A high-strength gel-based flexible electrochromic device, characterized in that, The device includes a first flexible electrode, an electrochromic layer, a gel electrolyte layer, and a second flexible electrode, which are stacked sequentially. The gel electrolyte layer contains a host material and a cationic salt distributed in the host material. The host material is an amino-terminated polyimide resin. The molar ratio of the cationic salt to the amino-terminated polyimide resin is (2% to 5%):

1.

2. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The cationic salt is selected from at least one of sodium salt, lithium salt, magnesium salt and aluminum salt.

3. The high-strength gel-based flexible electrochromic device according to claim 2, characterized in that, The cation salt is selected from at least one of lithium perchlorate, sodium perchlorate, magnesium perchlorate, magnesium chloride, sodium chloride, and lithium chloride.

4. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The thickness of the gel electrolyte layer is 10–100 μm.

5. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The first flexible electrode comprises a flexible conductive substrate and a conductive material formed on the surface of the flexible conductive substrate; the flexible conductive substrate is at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene, polyethylene, and polyvinyl chloride; and the conductive material is selected from at least one of transparent conductive oxide and metal nanowires. The surface sheet resistance of the first flexible electrode is 10–40 Ω / cm 2 Transmittance ≥75%.

6. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The second flexible electrode comprises a flexible conductive substrate and a conductive material formed on the surface of the flexible conductive substrate; the flexible conductive substrate is at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene, polyethylene, and polyvinyl chloride, and the conductive material is selected from at least one of transparent conductive oxide and metal nanowires; The surface sheet resistance of the second flexible electrode is 10–40 Ω / cm 2 Transmittance ≥75%.

7. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The electrochromic layer is made of at least one of inorganic oxides, PEDOT, polyaniline, and viologen, wherein the inorganic oxide is selected from WO3. 3-x The electrochromic layer contains at least one of V2O5, MoO3, Bruce Blue, and TiO2; the thickness of the electrochromic layer is 100–500 nm.

8. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The method for preparing the gel electrolyte layer includes: (1) Dissolve the cationic salt in an organic solvent to obtain a cationic salt solution; (2) Add the dianhydride monomer and the diamine monomer to the cationic salt solution and mix to obtain an amino-terminated polyamic acid solution; (3) Add crosslinking agent, dehydrating agent and catalyst to amino-terminated polyamic acid solution and mix to obtain mixed solution; (4) The mixed solution is coated onto the substrate and left to stand at 30-80°C for 10 min to 2 h to obtain the gel electrolyte layer.

9. The high-strength gel-based flexible electrochromic device according to claim 8, characterized in that, The organic solvent is at least one of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and dimethyl glycol ether (DME). The concentration of the cation salt solution is 0.5–2 mol / L; The total mass ratio of the dianhydride monomer and the diamine monomer to the cationic salt solution is 1:(5-20). The molar ratio between the dianhydride monomer and the diamine monomer is n:(n+1), where n≥500; The dianhydride monomer is selected from one of pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and diphenyl ether tetracarboxylic dianhydride, and the diamine monomer is selected from at least one of hexylene diamine, decylene diamine, diaminodiphenylmethane, diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, m-toluene diamine, and diaminodiphenyl sulfone.

10. The high-strength gel-based flexible electrochromic device according to claim 8, characterized in that, The crosslinking agent is selected from at least one of triglycidyl-p-aminophenol, triglycidyl-triisocyanate, tetraglycidyl-diaminodiphenylmethane, tetraglycidyl-diphenyldiamine, and pyromellitic acid chloride, and the amount added is 1% to 5% of the total mass of the amino-terminated polyamic acid solution; The dehydrating agent is selected from at least one of acetic anhydride, propionic anhydride, valeric anhydride, and dimethyl ketone, and the amount added is 0.5% to 5% of the total mass of the amino-terminated polyamic acid solution; The catalyst is selected from at least one of pyridine, 4-methylpyridine, 3,4-dimethylpyridine, isoquinoline and triethylamine, and is added in an amount of 0.1% to 1% of the total mass of the amino-terminated polyamic acid solution.

11. The high-strength gel-based flexible electrochromic device according to claim 1, characterized in that, The high-strength gel-based flexible electrochromic device exhibits an electrochromic performance degradation of less than 10% after 1000 consecutive bending cycles.

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