Polymer / ionic liquid-based gel electrolyte material, and preparation method and application thereof

Abstract

The present application relates to the field of electrolyte materials, and particularly relates to a polymer / ionic liquid-based gel electrolyte material, a preparation method and application thereof.The polymer / ionic liquid-based gel electrolyte material comprises polymer / ionic liquid nanofibers and an alkali metal salt solution; wherein the polymer / ionic liquid nanofibers comprise a thermoplastic polymer with an imidazole type ionic liquid modified surface.The polymer / ionic liquid nanofibers prepared by the present application have a maximum all-trans polar conformation, and further interact with an alkali metal salt electrolyte, thereby improving the interface ion conductivity and imparting the electrolyte material with extremely high optical transparency.The polymer / ionic liquid-based gel electrolyte material prepared by the present application shows excellent color change when assembled into an electrochromic device with an electrochromic electrode material, and exhibits good performance at-20 DEG C to 60 DEG C.

Description

Technical Field

[0001] This invention relates to the field of electrolyte materials, and more particularly to a polymer / ionic liquid-based gel electrolyte material, its preparation method, and its application. Background Technology

[0002] Electrochromic technology is a phenomenon that regulates light and heat with low energy consumption and high efficiency under an applied voltage, and it has broad application prospects in energy conservation and smart technology. Typically, electrochromic devices consist of five parts: a transparent conductive layer, an electrochromic layer, an electrolyte layer, an ion storage layer, and a transparent conductive layer. Currently, to improve the overall performance of the device, most research focuses on the preparation and design of high-performance electrochromic layer materials, with less attention paid to exploring and designing the electrolyte layer as an essential channel for ion transport. However, the electrolyte layer is not only responsible for conducting ions between electrodes, but also affects the safety and overall performance of the device. Therefore, improving the material properties of the electrolyte layer is of great significance for optimizing electrochromic devices and promoting the development of electrochromic energy-saving technology.

[0003] Generally, an ideal electrolyte for electrochromic devices should possess excellent mechanical, chemical, and thermal stability, high optical transmittance, ease of fabrication, low cost, and high voltage resistance. However, traditional liquid electrolytes face limitations in device applications, such as easy leakage and difficulty in encapsulation. Meanwhile, solid electrolytes also face challenges such as unstable contact interfaces with electrodes, low ionic conductivity, and high fabrication costs. Therefore, developing quasi-solid polymer electrolytes that are environmentally friendly, easy to fabricate, and combine the advantages of both liquid and solid electrolytes is crucial for solving these problems.

[0004] Polymers are widely used as substrates for polymer electrolytes. The all-trans polar phase, which exhibits maximum self-polarization in its molecular chain, possesses excellent electrochemical performance and enhances charge transfer capabilities. However, in single polymers, the nonpolar phase is readily obtained through melt crystallization, while the polar phase is more difficult to form directly. Therefore, polymers still have limitations as electrolyte substrates. Current optimization methods include doping with inorganic or nanofillers, adding nucleating agents, using mechanical stretching to force molecular conformation, and electrospinning. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention provides a polymer / ionic liquid-based gel electrolyte material, its preparation method, and its applications. The method uses an imidazole-type ionic liquid to modify a thermoplastic polymer and forms a self-supporting, multi-level nanofiber membrane through electrostatic interaction. The polymer / ionic liquid nanofibers exhibit a maximally trans polar conformation and interact with an alkali metal salt electrolyte, thereby enhancing interfacial ionic conductivity and imparting extremely high optical transparency to the electrolyte material. The prepared polymer / ionic liquid-based gel electrolyte material, when assembled with an electrochromic electrode material, displays excellent color changes and exhibits good performance from -20℃ to 60℃.

[0006] Therefore, the first aspect of the present invention provides a polymer / ionic liquid-based gel electrolyte material, the polymer / ionic liquid-based gel electrolyte material comprising polymer / ionic liquid nanofibers and an alkali metal salt solution;

[0007] The polymer / ionic liquid nanofibers include thermoplastic polymers whose surfaces are modified with imidazole-type ionic liquids.

[0008] The polymer / ionic liquid-based gel electrolyte material provided by this invention uses imidazole-type ionic liquid to modify and regulate the polymer's microscopic molecular structure, which is beneficial to the ion transport and interfacial stability of the electrolyte material. The addition of alkali metal salt solution not only improves the interfacial ionic conductivity, but also endows the electrolyte material with extremely high optical transparency, significantly improving the electrochemical performance of the system.

[0009] According to an embodiment of the present invention, the alkali metal salt in the alkali metal salt solution includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium sulfate, sodium hexafluorophosphate, sodium bis(trifluoromethanesulfonyl)imide, potassium sulfate, and potassium hydroxide.

[0010] According to embodiments of the present invention, the alkali metal salt solution further includes an ester organic solvent.

[0011] According to embodiments of the present invention, the ester organic solvent includes at least one of ethyl acetate, methyl methacrylate, ethylene carbonate, propylene carbonate, diethyl carbonate, and triethyl phosphate.

[0012] According to an embodiment of the present invention, the content of the thermoplastic polymer in the polymer / ionic liquid nanofiber is 49.99 wt%-99.99 wt%, preferably 60 wt%-90 wt%.

[0013] According to an embodiment of the present invention, the content of the imidazole-type ionic liquid is 0.01wt%-50wt%, preferably 1wt%-20wt%.

[0014] According to embodiments of the present invention, the thermoplastic polymer includes at least one of polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, or polyvinylidene fluoride-hexafluoropropylene.

[0015] According to embodiments of the present invention, the imidazole-type ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0016] A second aspect of the present invention provides a method for preparing the polymer / ionic liquid-based gel electrolyte material described in the first aspect, comprising the following steps:

[0017] Preparation of polymer / ionic liquid nanofibers;

[0018] Preparation of alkali metal salt solutions;

[0019] The polymer / ionic liquid nanofibers were immersed in an alkali metal salt solution, removed, and allowed to stand to obtain the polymer / ionic liquid-based gel electrolyte material.

[0020] This invention provides a polymer / ionic liquid-based gel electrolyte material prepared by this method. The material exhibits good electrochemical performance and extremely high optical transparency.

[0021] According to an embodiment of the present invention, the immersion time is 1 min to 120 min.

[0022] According to an embodiment of the present invention, every 1cm 2 The polymer / ionic liquid nanofibers are coated with 0.01 mL to 1 mL of alkali metal salt solution.

[0023] According to an embodiment of the present invention, the concentration of the alkali metal salt solution is 0.01 mol / L to 50 mol / L.

[0024] According to an embodiment of the present invention, the preparation process of the polymer / ionic liquid nanofibers includes:

[0025] A mixed solution containing a thermoplastic polymer and an imidazole ionic liquid was prepared, and a polymer / ionic liquid nanofiber precursor was obtained by electrospinning.

[0026] The polymer / ionic liquid nanofiber precursor is annealed to obtain the polymer / ionic liquid nanofiber.

[0027] According to an embodiment of the present invention, the voltage of the electrospinning is 5kV-25kV, the flow rate is 0.01mL / h-20mL / h, and the collection distance is 10cm-30cm.

[0028] According to an embodiment of the present invention, the annealing temperature is 50℃-200℃ and the time is 6h-24h.

[0029] The third aspect of the present invention provides an application of the polymer / ionic liquid-based gel electrolyte material described in the first aspect or the polymer / ionic liquid-based gel electrolyte material obtained according to the preparation method described in the second aspect in electrochromic devices.

[0030] The polymer / ionic liquid-based gel electrolyte material proposed in this invention uses inexpensive raw materials, has a simple and easy-to-control preparation process, and offers high practicality and cost-effectiveness. When combined with an electrode material possessing electrochromic properties, this material forms a sandwich-structured electrochromic device, significantly improving the device's visible light modulation capability, accelerating the response speed, and extending its cycle life.

[0031] According to an embodiment of the present invention, the polymer / ionic liquid-based gel electrolyte material is used to combine with an electrochromic electrode material to assemble an electrochromic device.

[0032] According to an embodiment of the present invention, the electrochromic electrode material includes inorganic materials and / or organic materials.

[0033] According to an embodiment of the present invention, the inorganic material includes at least one of manganese dioxide, tungsten trioxide, or Prussian blue.

[0034] According to embodiments of the present invention, the organic material includes at least one of polypyrrole, polyaniline, or polythiophene.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 The X-ray diffraction pattern of the polymer / ionic liquid nanofibers prepared in Example 1 of the present invention is shown.

[0038] Figure 2 The image shows a scanning electron microscope image of the polymer / ionic liquid-based gel electrolyte material prepared in Example 1 of the present invention;

[0039] Figure 3The visible light transmission spectrum and optical photograph of the polymer / ionic liquid-based gel electrolyte material prepared in Example 1 of this invention are shown. Figure a is the visible light transmission spectrum; Figure b is the optical photograph.

[0040] Figure 4 The ionic conductivity-temperature curve of the polymer / ionic liquid-based gel electrolyte material prepared in Example 1 of the present invention is shown.

[0041] Figure 5 This image shows optical photographs of the color-changing effect of the polymer / ionic liquid-based gel electrolyte material prepared in Example 1 of this invention, assembled with Prussian blue and tungsten trioxide as positive and negative electrodes to form an electrochromic device. The image also includes the visible light transmission spectrum, transmittance versus time curves, and characterization of the device's cycling stability within a voltage range of -2V to 2V. Specifically, Figure a shows optical photographs of the color-changing effect of the electrochromic device at different voltages; Figure b shows the visible light transmission spectrum; Figure c shows the transmittance versus time curves; and Figure d shows the characterization of the electrochromic device's cycling stability within a voltage range of -2V to 2V. Detailed Implementation

[0042] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0043] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0045] To facilitate understanding of the invention, certain technical and scientific terms are specifically defined below. Unless otherwise expressly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0046] In this document, the terms “comprising” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0047] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0048] According to embodiments of the present invention, a first aspect of the present invention provides a polymer / ionic liquid-based gel electrolyte material, the polymer / ionic liquid-based gel electrolyte material comprising polymer / ionic liquid nanofibers and an alkali metal salt solution;

[0049] The polymer / ionic liquid nanofibers include thermoplastic polymers whose surfaces are modified with imidazole-type ionic liquids.

[0050] This invention uses imidazole-type ionic liquids to modify and regulate the microscopic molecular structure of thermoplastic polymers, which is beneficial to ion transport and interfacial stability of electrolyte materials. Through electrostatic interactions, a self-supporting multi-level nanofiber membrane is formed. The polymer / ionic liquid nanofibers exhibit a maximum all-trans polar conformation, which interacts with the alkali metal salt electrolyte. On the one hand, this improves polymer chain segment movement, accelerates the dissociation rate of alkali metal ions, and enhances interfacial ionic conductivity. On the other hand, the large specific surface area and three-dimensional network structure of the nanofibers increase the electrolyte filling volume and endow the electrolyte material with extremely high optical transparency. Therefore, the polymer / ionic liquid-based gel electrolyte material obtained by this invention possesses superior performance.

[0051] According to specific embodiments of the present invention, the type of alkali metal salt in the alkali metal salt solution is not particularly limited. As some specific examples, the alkali metal salt includes at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium sulfate, sodium hexafluorophosphate, sodium bis(trifluoromethanesulfonyl)imide, potassium sulfate, and potassium hydroxide.

[0052] According to specific embodiments of the present invention, the alkali metal salt solution further includes an ester-based organic solvent. The type of ester-based organic solvent is not particularly limited; as some specific examples, the ester-based organic solvent includes at least one selected from ethyl acetate, methyl methacrylate, ethylene carbonate, propylene carbonate, diethyl carbonate, and triethyl phosphate.

[0053] According to specific embodiments of the present invention, the content of the thermoplastic polymer in the polymer / ionic liquid nanofiber is 49.99wt%-99.99wt%, preferably 60wt%-90wt%. As some specific examples, the content of the thermoplastic polymer can be 49.99wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 99.99wt%, etc.

[0054] According to specific embodiments of the present invention, the content of the imidazole-type ionic liquid is 0.01wt%-50wt%, preferably 1wt%-20wt%. As some specific examples, the content of the imidazole-type ionic liquid can be 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, etc.

[0055] According to specific embodiments of the present invention, the type of thermoplastic polymer is not particularly limited. As some specific examples, the thermoplastic polymer includes at least one of polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, or polyvinylidene fluoride-hexafluoropropylene.

[0056] According to specific embodiments of the present invention, the type of imidazole-type ionic liquid is not particularly limited. As some specific examples, the imidazole-type ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt.

[0057] According to specific embodiments of the present invention, the diameter of the polymer / ionic liquid nanofibers is 10 nm-5000 nm. As some specific examples, the diameter of the polymer / ionic liquid nanofibers can be 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm, 5000 nm, etc. The polymer / ionic liquid nanofibers thus obtained have suitable porosity and can carry a certain mass of electrolyte to exert the excellent electrochemical performance of the quasi-solid-state electrolyte.

[0058] According to specific embodiments of the present invention, the length of the polymer / ionic liquid nanofibers is 1 μm-2000 μm. As some specific examples, the length of the polymer / ionic liquid nanofibers can be 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 500 μm, 1000 μm, 2000 μm, etc. This results in continuous nanofibers with strong mechanical robustness, capable of serving as a self-supporting electrolyte framework.

[0059] According to specific embodiments of the present invention, the material thickness of the polymer / ionic liquid nanofibers is 0.01 mm to 50 mm. The longer the electrospinning time, the thicker the accumulated fiber film. This thickness determines the overall thickness of the electrolyte and the distance between the two electrode materials in the electrochromic device. As some specific examples, the material thickness of the polymer / ionic liquid nanofibers can be 0.01 mm, 0.05 mm, 0.1 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, etc. The polymer / ionic liquid nanofibers obtained thus have suitable porosity and can carry a certain mass of electrolyte to exert the excellent electrochemical performance of the quasi-solid-state electrolyte.

[0060] According to embodiments of the present invention, a second aspect provides a method for preparing the polymer / ionic liquid-based gel electrolyte material described in the first aspect, comprising the following steps:

[0061] (1) Preparation of polymer / ionic liquid nanofibers.

[0062] According to specific embodiments of the present invention, the preparation method of the polymer / ionic liquid nanofibers is not particularly limited, but is preferably obtained by electrospinning, and the specific process includes:

[0063] A. Prepare a mixed solution containing a thermoplastic polymer and an imidazole ionic liquid, and obtain a polymer / ionic liquid nanofiber precursor by electrospinning;

[0064] According to specific embodiments of the present invention, the electrospinning voltage is 5kV-25kV, the flow rate is 0.01mL / h-20mL / h, and the collection distance is 10cm-30cm. As some specific examples, the electrospinning voltage can be 5kV, 10kV, 15kV, 20kV, 25kV, etc., the flow rate can be 0.01mL / h, 0.05mL / h, 0.1mL / h, 0.5mL / h, 1mL / h, 5mL / h, 10mL / h, 15mL / h, 20mL / h, etc., and the collection distance can be 10cm, 20cm, 30cm, etc.

[0065] According to specific embodiments of the present invention, the mixed solution further includes a solvent, the type of which is not particularly limited. As some specific examples, the solvent includes at least one of water, anhydrous ethanol, anhydrous methanol, acetone, ethylene glycol, and formamide.

[0066] B. Anneal the polymer / ionic liquid nanofiber precursor to obtain the polymer / ionic liquid nanofiber.

[0067] According to specific embodiments of the present invention, the annealing temperature is 50℃-200℃ and the time is 6h-24h. As some specific examples, the annealing temperature can be 50℃, 100℃, 150℃, 200℃, etc., and the time can be 6h, 12h, 18h, 24h, etc.

[0068] (2) Prepare alkali metal salt solutions.

[0069] According to specific embodiments of the present invention, the concentration of the alkali metal salt solution is not particularly limited. As some specific examples, the concentration of the alkali metal salt solution is 0.01 mol / L-50 mol / L, specifically 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 5 mol / L, 10 mol / L, 20 mol / L, 30 mol / L, 40 mol / L, 50 mol / L, etc.

[0070] (3) The polymer / ionic liquid nanofibers are immersed in an alkali metal salt solution, taken out and left to stand to obtain the polymer / ionic liquid-based gel electrolyte material.

[0071] The addition of alkali metal salt solution not only improves the interfacial ionic conductivity but also imparts extremely high optical transparency to the electrolyte material, significantly enhancing the electrochemical performance of the system.

[0072] According to specific embodiments of the present invention, the immersion time is 1 min to 120 min. As some specific examples, the immersion time can be 1 min, 5 min, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, etc.

[0073] According to a specific embodiment of the present invention, every 1cm 2 The polymer / ionic liquid nanofibers are coated with 0.01 mL to 1 mL of alkali metal salt solution. This coating amount is optimal for electrolyte preparation, preventing the solution from being squeezed out of the fiber framework and avoiding unevenness on the electrolyte surface. As specific examples, each 1 cm... 2 The polymer / ionic liquid nanofibers can be attached with 0.01 mL, 0.05 mL, 0.1 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, and 1 mL of alkali metal salt solution.

[0074] According to a specific embodiment of the present invention, this step can also be performed by contacting the alkali metal salt solution with the polymer / ionic liquid nanofibers via drop coating, without affecting the properties of the resulting material.

[0075] According to embodiments of the present invention, a third aspect of the present invention provides the application of the polymer / ionic liquid-based gel electrolyte material described in the first aspect or the polymer / ionic liquid-based gel electrolyte material obtained according to the preparation method described in the second aspect in electrochromic devices.

[0076] The polymer / ionic liquid-based gel electrolyte material proposed in this invention uses inexpensive raw materials, has a simple and easy-to-control preparation process, and offers high practicality and cost-effectiveness. When combined with an electrode material possessing electrochromic properties, this material forms a sandwich-structured electrochromic device, significantly improving the device's visible light modulation capability, accelerating the response speed, and extending its cycle life.

[0077] According to a specific embodiment of the present invention, the polymer / ionic liquid-based gel electrolyte material is used to combine with an electrochromic electrode material to assemble an electrochromic device.

[0078] According to a specific embodiment of the present invention, the electrochromic electrode material includes inorganic materials and / or organic materials.

[0079] According to specific embodiments of the present invention, the type of inorganic material is not particularly limited. As some specific examples, the inorganic material includes at least one of manganese dioxide, tungsten trioxide, or Prussian blue.

[0080] According to specific embodiments of the present invention, the type of organic material is not particularly limited. As some specific examples, the organic material includes at least one of polypyrrole, polyaniline, or polythiophene.

[0081] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0082] Example 1

[0083] (1) Measure 2.0g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and dissolve it in 10mL of a mixed solvent of N,N-dimethylformamide and acetone (50:50, volume ratio), and stir at 50℃ for 6h to obtain a transparent polymer solution.

[0084] (2) 1 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid (BmImTFSI) was dispersed into the polymer solution and stirred at room temperature to obtain PVDF-HFP / BmImTFSI electrospinning precursor solution;

[0085] (3) The PVDF-HFP / BmImTFSI electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 15kV.

[0086] (4) The obtained PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 120℃ for 12h to obtain PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber.

[0087] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in propylene carbonate to make the total lithium salt concentration 1 M / L. After mixing evenly, immerse the PVDF-HFP / BmImTFSI polymer / ionic liquid nanofibers for 1 min, take them out and let them stand to obtain a uniform and transparent PVDF-HFP / BmImTFSI polymer / ionic liquid based gel electrolyte material.

[0088] Electrochromic devices are fabricated using conventional assembly methods in the field: PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material is bonded to ITO or FTO glass with Prussian blue and tungsten trioxide by an adhesive to form an electrochromic device with a sandwich structure.

[0089] The X-ray diffraction patterns of the polymer / ionic liquid nanofibers obtained according to the above preparation method are as follows: Figure 1 As shown, the scanning electron microscope image of the polymer / ionic liquid-based gel electrolyte material is as follows. Figure 2 As shown, the visible light transmission spectrum and optical photograph of the polymer / ionic liquid-based gel electrolyte material are as follows. Figure 3 As shown, the ionic conductivity-temperature curve of the polymer / ionic liquid-based gel electrolyte material is as follows: Figure 4 As shown, optical photographs of the color-changing effect of the electrochromic device at different voltages, transmission spectra in the visible light band, transmittance versus time curves, and characterization of the device's cycling stability within a voltage range of -2V to 2V are presented. Figure 5 As shown.

[0090] Example 2

[0091] (1) Take 5 mL of polymethyl methacrylate (PMMA) solution and dissolve it in 10 mL of a mixed solvent of N,N-dimethylformamide and acetone (50:50, volume ratio), and stir at room temperature for 2 h to obtain a transparent polymer solution.

[0092] (2) 1 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid (EmImTFSI) was dispersed into the polymer solution and stirred at room temperature to obtain PMMA / EmImTFSI electrospinning precursor solution;

[0093] (3) The PMMA / EmImTFSI electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 10kV.

[0094] (4) The obtained PMMA / EmImTFSI polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 120°C for 12 h to obtain PMMA / EmImTFSI polymer / ionic liquid nanofiber.

[0095] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in propylene carbonate to make the total lithium salt concentration 1 M / L. After mixing evenly, immerse the PMMA / EmImTFSI polymer / ionic liquid nanofibers for 1 min, take them out and let them stand to obtain a uniform and transparent PMMA / EmImTFSI polymer / ionic liquid based gel electrolyte material.

[0096] Example 3

[0097] (1) Measure 5g of polyacrylic acid (PAA) powder and dissolve it in 10mL of a mixed solvent of N,N-dimethylformamide and acetone (50:50, volume ratio), and stir at 100℃ for 6h to obtain a transparent polymer solution.

[0098] (2) 1 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid (EmImTFSI) was dispersed into the polymer solution and stirred at room temperature to obtain PAA / EmImTFSI electrospinning precursor solution;

[0099] (3) The PAA / EmImTFSI electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 10kV.

[0100] (4) The obtained PAA / EmImTFSI polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 120°C for 12 h to obtain PAA / EmImTFSI polymer / ionic liquid nanofiber.

[0101] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in propylene carbonate to make the total lithium salt concentration 1 M / L. After mixing evenly, immerse the PAA / EmImTFSI polymer / ionic liquid nanofibers for 1 min, take them out and let them stand to obtain a uniform and transparent PAA / EmImTFSI polymer / ionic liquid based gel electrolyte material.

[0102] Example 4

[0103] (1) Measure 2.0g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and dissolve it in 10mL of a mixed solvent of N,N-dimethylformamide and acetone (5:5, volume ratio), and stir at 50℃ for 6h to obtain a transparent polymer solution.

[0104] (2) 1 g of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid (BmImBF4) was dispersed in the polymer solution and stirred at room temperature to obtain PVDF-HFP / BmImBF4 electrospinning precursor solution;

[0105] (3) The PVDF-HFP / BmImBF4 electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 20kV.

[0106] (4) The obtained PVDF-HFP / BmImBF4 polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 120°C for 12 h to obtain PVDF-HFP / BmImBF4 polymer / ionic liquid nanofiber.

[0107] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in propylene carbonate to make the total lithium salt concentration 1 M / L. After mixing evenly, immerse the PVDF-HFP / BmImBF4 polymer / ionic liquid nanofibers for 1 min, take them out and let them stand to obtain a uniform and transparent PVDF-HFP / BmImBF4 polymer / ionic liquid based gel electrolyte material.

[0108] Example 5

[0109] (1) Measure 2.0g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and dissolve it in 10mL of a mixed solvent of N,N-dimethylformamide and acetone (5:5, volume ratio), and stir at 50℃ for 6h to obtain a transparent polymer solution.

[0110] (2) 0.5 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid (BmImTFSI) was dispersed into the polymer solution and stirred at room temperature to obtain PVDF-HFP / BmImTFSI electrospinning precursor solution;

[0111] (3) The PVDF-HFP / BmImTFSI electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 15kV.

[0112] (4) The obtained PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 150°C for 12h to obtain PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber.

[0113] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in propylene carbonate to make the total lithium salt concentration 1 M / L. After mixing evenly, immerse the PVDF-HFP / BmImTFSI polymer / ionic liquid nanofibers for 1 min, take them out and let them stand to obtain a uniform and transparent PVDF-HFP / BmImTFSI polymer / ionic liquid based gel electrolyte material.

[0114] Example 6

[0115] (1) Measure 2.0g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and dissolve it in 10mL of a mixed solvent of N,N-dimethylformamide and acetone (5:5, volume ratio), and stir at 50℃ for 6h to obtain a transparent polymer solution.

[0116] (2) 0.5 g of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid (BmImTFSI) was dispersed into the polymer solution and stirred at room temperature to obtain PVDF-HFP / BmImTFSI electrospinning precursor solution;

[0117] (3) The PVDF-HFP / BmImTFSI electrospinning precursor solution was drawn into a plastic syringe equipped with a 20G stainless steel needle and electrospinning was carried out under the conditions of a syringe injection rate of 1mL / h, a collection distance of 25cm, and an applied DC voltage of 15kV.

[0118] (4) The obtained PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber precursor was annealed in a vacuum drying oven at 120℃ for 12h to obtain PVDF-HFP / BmImTFSI polymer / ionic liquid nanofiber.

[0119] (5) Weigh a certain amount of lithium bis(trifluoromethanesulfonyl)imide and dissolve it in triethyl phosphate to make the total sodium salt concentration 2M / L. After mixing evenly, slowly drop it onto PVDF-HFP / BmImTFSI polymer / ionic liquid nanofibers to obtain a uniform and transparent PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material.

[0120] Comparative Example 1

[0121] The only difference between this comparative example and Example 1 is that the polymer selected in step (1) is polyurethane (PU), the content of which in the polymer / ionic liquid nanofiber is 80 wt%, and the mixed ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid (EmImTFSI).

[0122] The results showed that the obtained electrospun material had poor mechanical properties, and the microstructure contained beaded nanofibers, making it impossible to achieve the desired structure. Furthermore, it failed to support the same mass of electrolyte as in Example 1, resulting in poor electrochemical performance. Therefore, Comparative Example 1 did not achieve the performance of this invention.

[0123] Comparative Example 2

[0124] The only difference between this comparative example and Example 1 is that the polymer selected in step (1) is polyethylene oxide (PEO), the content of which in the polymer / ionic liquid nanofiber is 80 wt%, and the mixed ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ionic liquid (EmImTFSI).

[0125] The results showed that the obtained polymer / ionic liquid-based gel electrolyte material had low optical transmittance and high haze. Therefore, the visible light modulation capability of the assembled electrochromic device was reduced, and the desired effect of the invention was not achieved.

[0126] Comparative Example 3

[0127] The only difference between this comparative example and Example 1 is that the ionic liquid selected in step (2) is replaced with butylpyridinium tetrafluoride boron, and the content of this ionic liquid in the polymer / ionic liquid nanofiber is 10 wt%.

[0128] The results showed that the electrospinning needles were prone to clogging, making it difficult to form nanofibers. The formed fibers were short, rod-shaped clusters with a length of less than 1 μm. Furthermore, the nanofibers were easily broken after annealing and were difficult to separate from the aluminum foil. Therefore, the electrochemical performance achieved by this invention could not be realized.

[0129] Comparative Example 4

[0130] The only difference between this comparative example and Example 1 is that step (5) is omitted.

[0131] The results showed that the obtained polymer / ionic liquid-based gel electrolyte material had low optical transmittance, slow ion transport rate, and high internal impedance. Therefore, the assembled electrochromic device exhibited a slow fading response time and low visible light modulation capability, failing to achieve the desired effects of the present invention.

[0132] Comparative Example 5

[0133] The only difference between this comparative example and Example 1 is that the metal salt solution in step (5) is replaced with zinc sulfate / triethyl phosphate, and the concentration is 2M / L.

[0134] The results showed that the obtained polymer / ionic liquid-based gel electrolyte material precipitated white crystals upon prolonged exposure to air at room temperature. Therefore, its stability could not be guaranteed, and the desired effect of the invention was not achieved.

[0135] Depend on Figure 1 It can be seen that in Example 1 of this invention, the PVDF-HFP nanofibers modified with BmImTFSI have a much higher content of the all-trans polar β phase in the crystalline region than the pure polymer nanofibers without BmImTFSI, proving the induced polarization effect of BmImTFSI on the polymer; Figure 2 It can be seen that a PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material was successfully prepared, showing the hierarchical structure of PVDF-HFP / BmImTFSI polymer / ionic liquid nanofibers after being immersed in lithium salt solution. The nanofibers after electrolyte wetting have a diameter of approximately 150 nm and a length of approximately 100 μm. Figure 3 It is known that the PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material in this application has extremely high optical transmittance. Figure 3 a) and higher than that of pure PVDF-HFP nanofiber electrolyte material, indicating that the electrolyte sample does not interfere with the fading effect of the electrochromic electrode in the device. Figure 3 b) Applicable to the field of electrochromic energy-saving windows; by Figure 4 It is evident that the PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material in this application exhibits excellent ion migration rates, demonstrating good ionic conductivity at low, room, and high temperatures, with even better electrochemical performance at high temperatures; Figure 5 It is understood that the PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material in this application is combined with electrochromic material layers of tungsten trioxide and Prussian blue as anode and cathode, and assembled into a Prussian blue||PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material||tungsten trioxide electrochromic device; as Figure 5 a. When a -2.5V voltage is applied, the device exhibits a bluish-black coloration; when a 0V voltage is applied, the device exhibits a pale blue coloration; and when a 2.5V voltage is applied, the device exhibits an almost transparent faded coloration. Figure 5 b and 5c, when switching between -2.5V and 2.5V, devices using PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material exhibit superior modulation capability in color-changing performance; and, as Figure 5 d. Devices using the PVDF-HFP / BmImTFSI polymer / ionic liquid-based gel electrolyte material also exhibited superior cycling stability when switching voltages of -2V and 2V were applied.

[0136] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] 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 polymer / ionic liquid-based gel electrolyte material, characterized in that, The polymer / ionic liquid-based gel electrolyte material comprises polymer / ionic liquid nanofibers and alkali metal salt solutions; The polymer / ionic liquid nanofibers include thermoplastic polymers whose surfaces are modified with imidazole-type ionic liquids. The preparation process of the polymer / ionic liquid nanofibers includes: A mixed solution containing a thermoplastic polymer and an imidazole ionic liquid was prepared, and a polymer / ionic liquid nanofiber precursor was obtained by electrospinning. The polymer / ionic liquid nanofiber precursor was annealed to obtain the polymer / ionic liquid nanofiber. The annealing temperature is 120℃-200℃, and the time is 12h-24h.

2. The polymer / ionic liquid-based gel electrolyte material according to claim 1, characterized in that, The alkali metal salt in the alkali metal salt solution is selected from lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium sulfate, sodium hexafluorophosphate, sodium bis(trifluoromethanesulfonyl)imide, potassium sulfate, or potassium hydroxide.

3. The polymer / ionic liquid-based gel electrolyte material according to claim 2, characterized in that, The alkali metal salt solution also includes ester organic solvents.

4. The polymer / ionic liquid-based gel electrolyte material according to claim 3, characterized in that, The ester organic solvent is selected from ethyl acetate, methyl methacrylate, ethylene carbonate, propylene carbonate, diethyl carbonate, or triethyl phosphate.

5. The polymer / ionic liquid-based gel electrolyte material according to claim 1, characterized in that, The content of the thermoplastic polymer in the polymer / ionic liquid nanofiber is 49.99wt%-99.99wt%.

6. The polymer / ionic liquid-based gel electrolyte material according to claim 5, characterized in that, The content of the thermoplastic polymer in the polymer / ionic liquid nanofiber is 60wt%-90wt%.

7. The polymer / ionic liquid-based gel electrolyte material according to claim 1, characterized in that, The content of the imidazole-type ionic liquid is 0.01wt%-50wt%.

8. The polymer / ionic liquid-based gel electrolyte material according to claim 7, characterized in that, The content of the imidazole-type ionic liquid is 1wt%-20wt%.

9. The polymer / ionic liquid-based gel electrolyte material according to claim 1, characterized in that, The thermoplastic polymer is selected from polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, or polyvinylidene fluoride-hexafluoropropylene.

10. The polymer / ionic liquid-based gel electrolyte material according to claim 1, characterized in that, The imidazole-type ionic liquid is selected from 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt or 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt.

11. A method for preparing a polymer / ionic liquid-based gel electrolyte material according to any one of claims 1-10, characterized in that, Includes the following steps: Preparation of polymer / ionic liquid nanofibers; Preparation of alkali metal salt solutions; The polymer / ionic liquid nanofibers were immersed in an alkali metal salt solution, removed and allowed to stand to obtain the polymer / ionic liquid-based gel electrolyte material. The preparation process of the polymer / ionic liquid nanofibers includes: A mixed solution containing a thermoplastic polymer and an imidazole ionic liquid was prepared, and a polymer / ionic liquid nanofiber precursor was obtained by electrospinning. The polymer / ionic liquid nanofiber precursor was annealed to obtain the polymer / ionic liquid nanofiber. The annealing temperature is 120℃-200℃, and the time is 12h-24h.

12. The preparation method according to claim 11, characterized in that, The immersion time is 1 min to 120 min.

13. The preparation method according to claim 11, characterized in that, per 1cm 2 The polymer / ionic liquid nanofibers are coated with 0.01 mL to 1 mL of alkali metal salt solution.

14. The preparation method according to claim 11, characterized in that, The concentration of the alkali metal salt solution is 0.01 mol / L to 50 mol / L.

15. The preparation method according to claim 11, characterized in that, The electrospinning voltage is 5kV-25kV, the flow rate is 0.01mL / h-20mL / h, and the collection distance is 10cm-30cm.

16. The application of a polymer / ionic liquid-based gel electrolyte material according to any one of claims 1-10 or a polymer / ionic liquid-based gel electrolyte material obtained by the preparation method according to any one of claims 11-15 in an electrochromic device.

17. The application according to claim 16, characterized in that, The polymer / ionic liquid-based gel electrolyte material is used to combine with electrochromic electrode materials to assemble an electrochromic device.

18. The application according to claim 17, characterized in that, The electrochromic electrode material includes inorganic and / or organic materials.

19. The application according to claim 18, characterized in that, The inorganic material includes at least one of manganese dioxide, tungsten trioxide, or Prussian blue.

20. The application according to claim 18, characterized in that, The organic material includes at least one of polypyrrole, polyaniline, or polythiophene.

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