Preparation method and application of a temperature-sensitive hydrogel electrolyte

Abstract

The present application relates to the technical field of electrochromic materials, and particularly relates to a preparation method and application of a temperature-sensitive hydrogel electrolyte. The temperature-sensitive gel electrolyte of the present application controls the molecular weight of the temperature-sensitive segment by using the ATRP method, and introduces ionic monomers to form a double network structure. Different contents of the temperature-sensitive segment can cause the gel electrolyte to respond to different degrees, and the pseudo-double network structure composed of anion and cation monomers and the temperature-sensitive segment can provide stable mechanical properties of the electrolyte. In addition, the hydrogen bond, ionic bond and covalent bond contained in the gel electrolyte make the gel have self-healing properties and tensile properties. In addition, a small amount of different types of salt added to the gel can adjust the response temperature range and improve the ionic conductivity. Compared with the prior art, the hydrogel electrolyte has a wider electrochemical window, higher ionic conductivity and better stability. When applied to an electrochromic device, a higher contrast and a longer service life can be obtained.

Description

Preparation method and application of a thermosensitive hydrogel electrolyte Technical Field

[0001] This invention relates to the field of electrochromic materials technology, specifically to a method for preparing and applying a thermosensitive hydrogel electrolyte. Background Technology

[0002] Electrochromism refers to the phenomenon where electroactive materials undergo reversible redox reactions under the influence of an applied voltage, resulting in reversible color changes. Assembling electrochromic materials with ion-conducting layers, storage layers, and electrodes can create electrochromic devices with display functions. Broadly speaking, electrochromic materials can be divided into inorganic and organic types. Inorganic electrochromic materials, such as metal oxides like WO3, are widely used; organic materials include conductive polymers, viologen-based small molecules and their derivatives, and ester-based small molecules and their derivatives. Inorganic electrochromic materials have good stability but slow response speeds; among organic materials, viologen compounds have fast response speeds but poor stability and are difficult to fabricate into thin films, typically used in liquid-state devices, which have compromised safety.

[0003] The ion-conducting layer, also known as the electrolyte layer, can generally be classified into liquid electrolytes, solid electrolytes, and gel electrolytes. Compared to liquid electrolytes, gel electrolytes offer better safety and eliminate the risk of leakage; compared to pure solid electrolytes, gel electrolytes exhibit higher ion conductivity. Furthermore, the gel electrolyte layer can also function as an ion storage layer, simplifying device structure and reducing production costs and fabrication complexity. Currently, another significant factor hindering the large-scale application of electrochromic devices is the issue of flexibility, which is difficult to achieve with both liquid and solid electrolytes. In addition, the multifunctionality of devices is increasingly attracting attention. Therefore, the fabrication of a gel electrolyte with high conductivity, a wide voltage window, self-healing properties, and responsiveness to multiple stimuli is of great significance for the widespread application of electrochromic devices. Summary of the Invention

[0004] To address the problems of limited functionality and poor mechanical properties of existing hydrogel electrolytes, this invention provides a method for preparing a temperature-sensitive hydrogel electrolyte.

[0005] The technical solution of the present invention is achieved through the following method: providing a method for preparing a temperature-sensitive hydrogel electrolyte, comprising the following steps:

[0006] S1. Thermosensitive macromolecular initiators were synthesized using the ATRP method;

[0007] S2. The thermosensitive macromolecular initiator is added to the anionic and cationic mixed monomers, stirred evenly at a certain temperature, and then a catalyst, ligand and crosslinking agent are added. The polymerization is initiated by ATRP to form a gel polymer.

[0008] S3. Remove copper ions from the gel polymer, then freeze-dry the obtained polymer, and add an electrolyte salt solution dropwise to the freeze-dried polymer to obtain the temperature-sensitive hydrogel electrolyte.

[0009] Preferably, in one embodiment of the present invention, in step S1, the temperature-sensitive monomer used in synthesizing the temperature-sensitive macromolecular initiator is selected from at least one of the following: N-isopropylacrylamide (NIPAM), N-tert-butylacrylamide (DEAAM), N,N-diethylacrylamide, and 2-carboxy-N-isopropylacrylamide (CIPAAm).

[0010] Preferably, in one embodiment of the present invention, in step S2, the anionic monomer used is selected from at least one of the following: sodium 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonate (NaAMPS), sodium methpropylene sulfonate (SMAS), sodium styrene sulfonate (NaSS);

[0011] The cationic monomer used is selected from at least one of the following: N,N,N-trimethyl-3-(2-methylallylamino)-1-propanediamine chloride (MPTC), methacryloyloxyethyltrimethylammonium chloride (MTAC), and acryloyloxyethyltrimethylammonium chloride (DMAEA-Q).

[0012] Preferably, in one embodiment of the present invention, in step S1, the ATRP method requires cuprous bromide (CuBr), tris(2-dimethylaminoethyl)amine (Me6TREN), and ethyl 2-bromo-2-methylpropionate (EBiB) as the initiation system. Depending on the designed molecular weight, the molar ratio of the amount of the temperature-sensitive monomer to the initiator EBiB is 88:1 to 265:1.

[0013] Preferably, in one embodiment of the present invention, the molar ratio of cuprous bromide (CuBr), tris(2-dimethylaminoethyl)amine (Me6TREN), and ethyl 2-bromo-2-methylpropionate (EBiB) is 1:1.2:1.

[0014] Preferably, in one embodiment of the present invention, in step S2, the molar concentration ratio of the temperature-sensitive macromolecular initiator to the anionic monomer and the cationic monomer is 5.902 × 10⁻⁶. -4 :1:1~2.951×10 -3The molar ratio of the crosslinking agent N,N'-methylenebisacrylamide MBA to the anionic monomer is 0.02:1 to 0.06:1, the molar ratio of CuBr to Me6TREN and the thermosensitive macromolecular initiator is 10:6:1 to 9:9:1, the reaction temperature range is 15℃ to 28℃, and the reaction time is 3h to 48h.

[0015] Preferably, in one embodiment of the present invention, in step S3, the obtained gel needs to be soaked in water to remove copper ions, and the resulting colorless and transparent gel is freeze-dried; 0.125-0.5 mol of the electrolyte salt solution is added to the dried gel to obtain the temperature-sensitive hydrogel electrolyte.

[0016] On the other hand, the present invention also provides an electrochromic device, comprising a glass layer covered with conductive tape, a thermosensitive gel electrolyte, an electrochromic layer, and an FTO electrode; the thermosensitive gel electrolyte is prepared by the aforementioned method. The electrochromic device based on this gel electrolyte has a wide voltage window, high stability, is safe, environmentally friendly, and energy-saving, and has good application prospects.

[0017] Preferably, in one embodiment of the present invention, the electrochromic layer material used in the present invention is the inorganic electrochromic material tungsten trioxide (WO3).

[0018] Preferably, in one embodiment of the present invention, the method for preparing a WO3 electrochromic device containing a temperature-sensitive gel electrolyte includes the following steps:

[0019] (1) A gel electrolyte was prepared according to claim 3;

[0020] (2) WO3 electrochromic material was prepared on a cathode substrate;

[0021] (3) Apply sealant to the perimeter of the substrate covered by the electrochromic material in step (2);

[0022] (4) Place the gel electrolyte on the electrode obtained in step (3);

[0023] (5) Cover the electrode obtained in step (4) with an anode conductive substrate, which is glass with conductive tape on its surface.

[0024] In the above preparation method, the inorganic electrochromic material described in step (2) is uniformly covered on the surface of the cathode substrate by preparing a precursor and then spin-coating and firing it.

[0025] The beneficial effects are as follows:

[0026] The thermosensitive gel electrolyte of this invention controls the molecular weight of the thermosensitive segments using the ATRP method and introduces ionic monomers to form a double-network structure. Different contents of thermosensitive segments can induce different degrees of response in the gel electrolyte, and the pseudo-double-network structure composed of anionic and cationic monomers and thermosensitive segments provides stable mechanical properties of the electrolyte. Furthermore, the hydrogen bonds, ionic bonds, and covalent bonds contained in the gel electrolyte endow the gel with self-healing properties and stretchability. Adding small amounts of different types of salts to the gel can regulate the response temperature range and improve ionic conductivity. Compared with existing technologies, this hydrogel electrolyte has a wider electrochemical window, higher ionic conductivity, and better stability. When applied to electrochromic devices, it can achieve higher contrast and a longer lifespan. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the device structure according to an embodiment of the present invention.

[0028] Figure 2 shows the morphology and temperature sensitivity of the gel in the comparative embodiment of the present invention; Figure 2(a) shows the situation of the comparative embodiment, and Figure 2(b) shows the situation of the comparative embodiment.

[0029] Figure 3 is a record of the tensile properties of the gel in Example 5 of the present invention; Figure 2(a) shows the situation before stretching, and Figure 2(b) shows the situation after stretching.

[0030] Figure 4 is a schematic diagram of the temperature-sensitive cycling performance of the pure gel in Example 9 of the present invention.

[0031] Figure 5 is a comparison of the temperature-sensitive response of the pure gel in Example 9 of the present invention after adding different amounts of sodium sulfate. Samples one to four were respectively added with sodium sulfate at concentrations of 0.125 mol / L, 0.25 mol / L, 0.375 mol / L, and 0.5 mol / L.

[0032] Figure 6 shows the color change of the WO3 electrochromic device with PNIPAM (Mw = 10000)-PNaAMPS-PMPTC (PNIPAM mass fraction is 1.2%) gel electrolyte in Example 1 of the present invention at 0V and -1.5V.

[0033] Figure 7 shows the CV curve of the WO3 electrochromic device of PNIPAM (Mw = 10000)-PNaAMPS-PMPTC (PNIPAM mass fraction is 1.2%) gel electrolyte in Example 1 of the present invention.

[0034] Figure 8 shows the UV-Vis transmission spectra of the WO3 electrochromic device with PNIPAM (Mw = 10000)-PNaAMPS-PMPTC (PNIPAM mass fraction is 1.2%) gel electrolyte in Example 1 of the present invention at different ground potentials.

[0035] Figure 9 shows the optical contrast of the WO3 electrochromic device using PNIPAM (Mw = 10000)-PNaAMPS-PMPTC (PNIPAM mass fraction is 1.2%) gel electrolyte in Example 1 of this invention.

[0036] Figure 10 is a schematic diagram of the optical contrast and cycle stability of the thermosensitive gel electrolyte WO3 electrochromic device in Example 7 of the present invention.

[0037] Figure 11 is a schematic diagram of the optical contrast and cycle stability of the thermosensitive gel electrolyte WO3 electrochromic device in Example 9 of the present invention.

[0038] Figure 12 is a schematic diagram of the optical contrast and cycle stability of the thermosensitive gel electrolyte WO3 electrochromic device in Example 10 of the present invention.

[0039] Figure 13 is a schematic diagram of the optical contrast and cycle stability of Comparative Example 3 in this invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0042] Where specific experimental steps or conditions are not specified in the examples, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0043] Compounds for which no synthetic method was mentioned in the examples were all commercially available raw materials. Solvents and reagents used in the examples were all available from the domestic chemical market, for example, from Sinopharm Reagent Co., Ltd., Anengji Co., Ltd., Aladdin Co., Ltd., and Shanghai Bid Pharmaceutical Co., Ltd. Alternatively, those skilled in the art can synthesize them using well-known methods.

[0044] Example 1:

[0045] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0046] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0480 g, 0.311 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum-pump three times and place in a glove box. Take 0.8 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (9.00 μL, 0.0362 mmol) and CuBr (0.0040 g, 0.0280 mmol) and stir. Then pour the mixture into a mold and react at room temperature for 4 h before removing it.

[0047] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0048] Example 2:

[0049] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0050] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0160 g, 0.105 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum-pump three times and place in a glove box. Take 0.8 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (9.00 μL, 0.0362 mmol) and CuBr (0.0040 g, 0.0280 mmol) and stir. Then pour the mixture into a mold and react at room temperature for 4 h before removing it.

[0051] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0052] Example 3:

[0053] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0054] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0325 g, 0.211 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 0.8 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (9.00 μL, 0.0362 mmol) and CuBr (0.0040 g, 0.0280 mmol) and stir. Then pour the mixture into a mold and react at room temperature for 4 h before removing it.

[0055] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0056] Example 4:

[0057] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0058] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0325 g, 0.211 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 1.2 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (13.47 μL, 0.0504 mmol) and CuBr (0.0060 g, 0.0420 mmol) and stir. Then pour into a mold and react at room temperature for 10 h before removing.

[0059] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0060] Example 5:

[0061] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0062] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0160 g, 0.105 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 1.2 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (13.47 μL, 0.0504 mmol) and CuBr (0.0060 g, 0.0420 mmol) and stir. Then pour into a mold and react at room temperature for 10 h before removing.

[0063] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0064] Example 6:

[0065] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0066] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0244 g, 0.158 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 1.2 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (13.47 μL, 0.0504 mmol) and CuBr (0.0060 g, 0.0420 mmol) and stir. Then pour into a mold and react at room temperature for 10 h before removing.

[0067] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0068] Example 7:

[0069] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0070] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0244 g, 0.158 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 1.5 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (16.85 μL, 0.0630 mmol) and CuBr (0.0075 g, 0.0525 mmol) and stir. Then pour into a mold and react at room temperature for 15 h before removing.

[0071] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Perform lyophilization on the resulting colorless, transparent gel. Add an appropriate amount of water to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0072] Example 8:

[0073] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0074] Step 2: Weigh the anionic monomer NaAMPS (2.422 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0244 g, 0.158 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum-pump three times and place in a glove box. Take 2.0 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (22.46 μL, 0.0841 mmol) and CuBr (0.0100 g, 0.0700 mmol) and stir. Then pour into a mold and react at room temperature for 20 h before removing.

[0075] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Freeze-dry the resulting colorless, transparent gel. Add 0.5 mol of sodium sulfate solution to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0076] Example 9:

[0077] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0078] Step 2: Weigh the anionic monomer NaAMPS (2.432 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0245 g, 0.159 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 4.0 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (44.93 μL, 0.1681 mmol) and CuBr (0.0200 g, 0.1400 mmol) and stir. Then pour into a mold and react at 15 °C for 15 h. Add EBiB (5 μL, 0.034 mmol) and react for another 9 h before removing.

[0079] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Freeze-dry the resulting colorless, transparent gel. Add 0.5 mol of sodium sulfate solution to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0080] Example 10:

[0081] Step 1: Take NIPAM (0.7019 g, 6.202 mmol) and add it to a single-necked round-bottom flask. Fill the flask with vacuum sealant three times and place it in a glove box. Add cuprous bromide (0.0101 g, 0.0704 mmol) to the flask, then add 20 ml of water, followed by tris(2-dimethylaminoethyl)amine (Me6TREN) (22.60 μL, 0.0846 mmol). Stir for 10 min, then add ethyl 2-bromo-2-methylpropionate (EBiB) (10.28 μL, 0.0700 mmol) dropwise. React at 30 °C for 4 h.

[0082] Step 2: Weigh the anionic monomer NaAMPS (2.432 g, 0.0053 mol), cationic monomer MPTC (2.338 g, 0.0053 mol), and MBA (0.0245 g, 0.159 mmol) into a 20 mL sample vial. Stir for 4 h, then vacuum three times and place in a glove box. Take 4.0 mL of the reaction solution from Step 1 and add it dropwise to the sample vial while stirring. After stirring for 4 h, add Me6TREN (44.93 μL, 0.1681 mmol) and CuBr (0.0200 g, 0.1400 mmol) and stir. Then pour into a mold and react at 15 °C for 15 h. Add EBiB (5 μL, 0.034 mmol) and react for another 9 h before removing.

[0083] Step 3: Soak the gel from Step 2 in 100 mL of deionized water for 48 hours, changing the water every 4 hours. Freeze-dry the resulting colorless, transparent gel. Add 0.125 mol of zinc chloride solution to the dried gel to obtain a temperature-sensitive gel electrolyte.

[0084] Comparative Example 1

[0085] Weigh out the following monomers: anionic monomer NaAMPS (2.416 g, 0.0053 mol), cationic monomer MPTC (2.334 g, 0.0053 mol), NIPAM (0.14 g, 0.0012 mol), MBA (0.0245 g, 0.159 mmol), and photoinitiator 2959 (0.0264 g, 0.118 mmol). Add these to a 20 mL sample vial and stir well. Pour the mixture into a mold. 505 mW / cm 2 After initiating for 10 minutes, a colorless and transparent gel was obtained.

[0086] Comparative Example 2

[0087] Weigh out the anionic monomer NaAMPS (2.416 g, 0.0053 mol), the cationic monomer MPTC (2.334 g, 0.0053 mol), and PNIPAM. 10000Add 0.14 g (0.0140 mmol), MBA (0.0245 g, 0.159 mmol), and photoinitiator 2959 (0.0237 g, 0.106 mmol) to a 20 mL sample vial and stir well. Pour into a mold and heat at 505 mW / cm². 2 After initiating for 10 minutes, a colorless and transparent gel was obtained.

[0088] Comparative Example 3

[0089] Sodium dodecyl sulfate (SDS) (0.02 g, 0.0693 mmol) was weighed and stirred in 40 mL of water for 30 min. Then, NIPAM (1 g, 0.0088 mol) and potassium persulfate (K₂S₂O₈) (0.01 g, 0.0370 mmol) were added to the solution, and the mixture was stirred for 30 min. The mixture was then heated at 80 °C for 5 h under a nitrogen atmosphere to obtain a sol. 0.5 mol LiClO₄ solution was added to the sol to obtain a thermosensitive sol electrolyte.

[0090] Results Experiment

[0091] The properties of the gels synthesized in Examples 1-10 and Comparative Examples 1-3 were compared (Table 1).

[0092] Table 1

[0093]

[0094]

[0095] Comparative Example 1 showed no temperature-sensitive effect, while Comparative Example 2 exhibited uneven temperature sensitivity, as shown in Figure 2. Comparative Example 3 had a mass fraction of 2.5% in water.

[0096] As shown in Table 1, the content of the temperature-sensitive segment affects the contrast of the temperature-sensitive response; the higher the content, the greater the contrast. The content of MBA affects the physical properties of the gel; only when the content is moderate will the gel achieve optimal hardness and softness, exhibiting good tensile properties, as in Example 5. Due to the presence of chemical bonds, the gel prepared by this method has higher cycling stability than the physically mixed gel of Comparative Example 2, maintaining its stability after 1000 cycles. The temperature-sensitive cycling stability is shown in Figure 4. Furthermore, the response temperature of the gel in the above examples can be adjusted by adding different amounts of salt, as shown in Figure 5.

[0097] Examples 1-10 and Comparative Example 3 were applied to an electrochromic device. The device was assembled according to steps 4-7, and a WO3 electrochromic material was prepared on a cathode substrate. Then, a sealant was applied to the perimeter of the substrate covered by the electrochromic material. A gel electrolyte was then placed on the resulting electrode; subsequently, an anode conductive substrate was covered, which was glass with conductive tape adhered to its surface.

[0098] After the devices were assembled, we conducted a series of studies on the electrochromic devices based on the above embodiments, testing the transmittance at the characteristic peaks over time, thereby obtaining the coloring time (t) of 11 devices. coloring ) and fading time (t) bleaching The results are shown in Table 2.

[0099] Table 2

[0100]

[0101]

[0102] Table 2 shows that even without the addition of additional salt solution, the resulting gel electrolyte still achieved high contrast and fast response speed when used in electrochromic devices. This indicates that the introduction of the ionic segment can improve the ionic conductivity of the thermosensitive gel. Furthermore, the gel with only a small amount of salt added showed even greater improvements in switching speed and stability.

[0103] The above examples demonstrate that this temperature-sensitive gel electrolyte is suitable for electrochromic devices, and the assembled devices exhibit high stability, high contrast, and fast switching speed. Figure 6 shows a photograph of the color change of the WO3 electrochromic device with gel electrolyte in Example 1. The device is colorless at 0V, and turns deep blue when a negative voltage of -1.5V is applied. When the temperature is raised to 39℃, the device changes from colorless and transparent to light white. Figure 7 shows the CV curve of the WO3 electrochromic device with gel electrolyte in Example 1. Figure 8 shows the UV-Vis transmission spectrum of the device at different potentials in Example 1. The figure shows that the maximum transmittance at 700nm is 88%, and the maximum transmittance at 1000nm is 96%. Figure 9 shows the optical contrast of the electrochromic device in Example 1. The figure shows that the optical contrast at 700nm is 57.5%. Figure 10 is a schematic diagram of the optical contrast and cycling stability of Example 7. It shows that the contrast is 53.2%, and the device remains stable after 7500s of cycling. Figure 11 shows the optical contrast and cycle stability of Example 9. It can be seen that the response speed of the device is significantly improved after adding a small amount of sodium sulfate, with a contrast of 59.5%, and only slight decay after 100 cycles. It is worth noting that the addition of a small amount of zinc chloride gel (Example 10) resulted in a device switching speed of 5.3s, and it can still maintain a high contrast of 50% after 1500 cycles, as shown in Figure 12.

[0104] To demonstrate the characteristics of this embodiment, comparative examples were designed and synthesized. Comparative Example 1 involved the physical mixing of three monomers followed by free radical polymerization. Test results showed that no temperature-sensitive segment was formed, the molecular weight was uncontrollable, and multifunctionality could not be achieved. Comparative Example 2 involved the physical mixing of temperature-sensitive molecules and ionic monomers followed by free radical polymerization. Test results showed that no strong chemical bonds were formed, and uneven agglomeration occurred during heating, resulting in poor stability. Comparative Example 3 was a PNIPAM sol containing lithium perchlorate. Due to the lack of ionic segments, its ionic conductivity was low, leading to a slow device switching speed, even slower than the pure hydrogel of this invention, as shown in Figure 13. Furthermore, due to the absence of ionic bonds and other interactions, this sol had no mechanical properties and was unsuitable for fabricating flexible devices.

[0105] The thermosensitive gel electrolyte prepared in this invention utilizes the ATRP method to control the molecular weight of the thermosensitive segments and introduces ionic monomers to form a dual-network structure. Different amounts of thermosensitive segments elicit varying degrees of response in the gel electrolyte. The pseudo-dual-network structure composed of anionic and cationic monomers and thermosensitive segments provides stable mechanical properties for the electrolyte. Furthermore, the hydrogen bonds, ionic bonds, and covalent bonds contained in the gel electrolyte endow the gel with self-healing properties and stretchability. Adding small amounts of different types of salts to the gel can regulate the response temperature range and improve ionic conductivity. Compared with existing technologies, this hydrogel electrolyte exhibits a wider electrochemical window, higher ionic conductivity, and better stability. When applied to electrochromic devices, it can achieve higher contrast and a longer lifespan.

[0106] The thermosensitive monomers and ionic monomers listed above are only a partial representative. Other thermosensitive ionic gel electrolytes with the same concept are all within the scope of protection of this patent.

[0107] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a temperature-sensitive hydrogel electrolyte, characterized in that, Includes the following steps: S1. A temperature-sensitive macromolecular initiator is synthesized using the ATRP method; S2. The temperature-sensitive macromolecular initiator is added to a mixture of anionic and cationic monomers, stirred evenly at a certain temperature, and a catalyst, ligand, and crosslinking agent are added. The polymerization is initiated using the ATRP method to form a gel polymer; S3. Copper ions are removed from the gel polymer, and the resulting polymer is lyophilized. An electrolyte salt solution is added dropwise to the lyophilized polymer to obtain the temperature-sensitive hydrogel electrolyte; wherein, in step S1, the temperature-sensitive monomer used in synthesizing the temperature-sensitive macromolecular initiator is selected from at least one of the following: N-isopropylacrylamide, N-tert-butylacrylamide, N,N... -Diethylacrylamide, 2-carboxy-N-isopropylacrylamide; In step S2, the anionic monomer used is selected from at least one of the following: sodium 2-methyl-2-[(1-oxo-2-propenyl)amino]-1-propanesulfonate, sodium methpropylenesulfonate, sodium styrenesulfonate; The cationic monomer used is selected from at least one of the following: N,N,N-trimethyl-3-(2-methylallylamino)-1-propanediamine chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium chloride; The molar ratio of the thermosensitive macromolecular initiator to the anionic monomer and the cationic monomer is 5.902 × 10⁻⁶. -4 :1:1~2.951×10 -3 The molar ratio of crosslinking agent to anionic monomer is 0.02:1 to 0.06:

1.

2. The preparation method according to claim 1, characterized in that, In step S1, the ATRP method uses cuprous bromide, tris(2-dimethylaminoethyl)amine, and ethyl 2-bromo-2-methylpropionate as the initiation system. Depending on the designed molecular weight, the molar ratio of the thermosensitive monomer to the initiator EBiB is 88:1 to 265:

1.

3. The preparation method according to claim 2, characterized in that, The molar ratio of cuprous bromide, tris(2-dimethylaminoethyl)amine, and ethyl 2-bromo-2-methylpropionate is 1:1.2:

1.

4. The preparation method according to claim 2, characterized in that, In step S2, the molar ratio of cuprous bromide, tris(2-dimethylaminoethyl)amine, and thermosensitive macromolecular initiator is 10:6:1 to 9:9:1, the reaction temperature range is 15℃ to 28℃, and the reaction time is 3h to 48h.

5. The preparation method according to claim 1, characterized in that, In step S3, the obtained gel is soaked in water to remove copper ions, and the resulting colorless and transparent gel is freeze-dried; 0.125-0.5 mol of the electrolyte salt solution is added to the dried gel to obtain the thermosensitive hydrogel electrolyte.

6. An electrochromic device, characterized in that, It comprises a glass layer covered with conductive tape, a thermosensitive hydrogel electrolyte layer, an electrochromic layer, and an FTO electrode layer; the thermosensitive hydrogel electrolyte is prepared by the method described in any one of claims 1-5.

7. The electrochromic device according to claim 6, characterized in that, The electrochromic layer is made of tungsten trioxide, an inorganic electrochromic material.

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