A room-temperature in-situ spontaneously polymerizable ionogel electrolyte composition, the electrolyte, and its applications.

Abstract

This invention belongs to the field of electrochromic devices, specifically relating to a room-temperature, in-situ spontaneously polymerizable ionic gel electrolyte composition, which can be used in devices such as smart windows and flexible displays, as well as the electrolyte and its applications. The composition includes a liquid precursor solution and an initiator; the liquid precursor solution is a liquid containing a polymer network framework material, an ionic liquid electrolyte, 1,3-dioxolane, an epoxy crosslinking agent, a viologen derivative electrochromic material, and a ferrocene derivative counter electrode material; the initiator is a combination of lithium bis(trifluoromethanesulfonyl)imide and the initiator trifluoroacetic acid; the cation of the ionic liquid electrolyte is selected from at least one of imidazolium cations, pyrrolidineonium cations, pyridinium cations, and / or quaternary ammonium cations. The composition of this invention can generate a gel electrolyte without external energy input, and the electrochromic device prepared therefrom possesses characteristics such as high ionic conductivity, excellent optical performance, good interfacial stability, and long cycle life.

Description

Technical Field

[0001] This invention belongs to the field of electrochromic devices, specifically relating to a room-temperature in-situ spontaneously polymerizable ion gel electrolyte composition that can be used in devices such as smart windows and flexible displays, as well as the electrolyte and its applications. Background Technology

[0002] Electrochromic devices are functional devices that can reversibly adjust their optical properties (such as transmittance and reflectance) under an applied voltage. They have broad application prospects in fields such as smart building windows, energy-saving displays, anti-glare rearview mirrors, flexible electronics, and military camouflage. Electrochromic devices typically employ a "sandwich" structure, consisting of a transparent electrode, an electrochromic layer, an electrolyte layer, and a counter electrode. The electrolyte layer not only plays a crucial role in transferring ions between the positive and negative electrodes and maintaining charge balance, but also directly affects the device's response speed, cycle life, safety, and fabrication process.

[0003] Currently, the electrolytes widely used in electrochromic devices mainly fall into three categories: liquid, solid, and gel (quasi-solid). However, each has significant drawbacks: liquid electrolytes, while possessing high ionic conductivity and good electrode wettability, pose safety hazards such as volatility, leakage, and flammability. They also have poor mechanical strength, making them unsuitable for flexible encapsulation, and may corrode electrode materials during long-term use. Solid electrolytes offer better mechanical strength and safety, but generally have low ionic conductivity, poor contact with the electrode interface, and high impedance, leading to increased device operating voltage and slow response. Gel electrolytes combine the advantages of both types of electrolytes to some extent, but current fabrication technologies still face two major bottlenecks: first, most employ a non-in-situ method of "gelling first, then assembling," resulting in poor contact between the gel and the electrode interface and high impedance; second, existing in-situ gelation technologies (such as photopolymerization or thermal polymerization) rely on external energy input, making the process complex and costly, thus limiting their large-scale application in large-area, flexible, and complex structure devices. In addition, traditional gel electrolytes often use volatile organic solvents, which have poor long-term stability. Some gels also suffer from reduced light transmittance due to crystallization or phase separation, which in turn has an adverse effect on the visual performance of the device. Summary of the Invention

[0004] (a) Technical problems to be solved To address key issues in the fabrication process of existing gel electrolytes for electrochromic devices, such as reliance on external energy (light or heat) for initiation, difficulty in achieving simple in-situ molding at room temperature, and compatibility issues between the electrolyte system and high-performance electrochromic materials, this invention provides a room-temperature in-situ spontaneously polymerizing ion-gel electrolyte composition and its preparation method. Utilizing the highly reactive cyclic monomer 1,3-dioxolane, ring-opening polymerization is achieved under the catalysis of a unique co-initiation system composed of lithium salt and protic acid. Simultaneously reacting with a multifunctional epoxy crosslinking agent, a gel electrolyte with a three-dimensional network structure is directly crosslinked within the device without any external energy input. The gel electrolyte of this invention features a simple and environmentally friendly preparation process and is perfectly compatible with specially designed electrochromic materials, thereby enabling the fabrication of integrated electrochromic devices with high ionic conductivity, excellent optical performance, good interfacial stability, and long cycle life.

[0005] (II) Technical Solution To achieve the above objectives, the main technical solutions adopted by the present invention include: In a first aspect, the present invention provides a room-temperature in-situ spontaneously polymerizable ion gel electrolyte composition, comprising: a liquid precursor solution and an initiator; The liquid precursor solution is a homogeneous liquid comprising a polymer network framework material, an ionic liquid electrolyte, 1,3-dioxolane, an epoxy crosslinking agent, a viologen derivative electrochromic material, and a ferrocene derivative counter electrode material. The initiator is a combination of lithium bis(trifluoromethanesulfonylimide) and trifluoroacetic acid initiator; The ionic liquid electrolyte comprises cations and anions, wherein the cations are selected from at least one of imidazolium cations, pyrrolidineium cations, pyridinium cations, and / or quaternary ammonium cations.

[0006] According to a preferred embodiment of the present invention, the polymer network framework material is selected from at least one of polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), polybutyl methacrylate (PBMA), polyurethane (PU), polyglycidyl methacrylate (PGMA), polyisooctyl acrylate (PEHA), polyethyl methacrylate (PEMA), polyacrylamide (PAM), polycaprolactone diol (PCL), polylauryl methacrylate (PLMA), poly(N-vinylpyrrolidone) (PVP), poly(N-isopropylacrylamide) (PNIPAN), poly(hydroxyethyl methacrylate) (PHEMA), and polypropylene glycol (PPG).

[0007] According to a preferred embodiment of the present invention, the imidazolium cation is a monosubstituted imidazolium cation, particularly an imidazolium having a C1-C12 alkyl substituent at the 1-position, preferably at least one selected from 1-methylimidazolium, 1-ethylimidazolium, 1-propylimidazolium, 1-butylimidazolium, 1-hexylimidazolium, 1-octylimidazolium, 1-decylimidazolium, and 1-dodecylimidazolium; or The imidazolium cation is a disubstituted imidazolium cation, particularly an imidazolium with C1-C10 alkyl substituents independently at the 1 and 3 positions, preferably at least one of 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1-butyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-propyl-3-ethylimidazolium, 1-pentyl-3-methylimidazolium, 1-butyl-3-ethylimidazolium, 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-butyl-3-propylimidazolium, 1-octyl-3-methylimidazolium, 1-octyl-3-ethylimidazolium, and 1,3-octylimidazolium; or The imidazolium cation is a polysubstituted imidazolium cation, especially an imidazolium with C1-C8 alkyl substituents independently at positions 1, 2, and 3, preferably at least one of 1,2,3-trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-pentyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl-2,3-dimethylimidazolium, and 1-nonyl-2,3-dimethylimidazolium; The pyrrolidineonium cation is a pyrrolidineonium with two C1-C6 alkyl substituents connected to N, preferably at least one selected from N-ethyl-N-methylpyrrolidineonium, N-propyl-N-methylpyrrolidineonium, N-butyl-N-methylpyrrolidineonium, N-pentyl-N-methylpyrrolidineonium, and N-hexyl-N-methylpyrrolidineonium; The pyridinium cation is an N-linked C2-C9 alkyl-substituted pyridinium, preferably at least one selected from N-ethylpyridinium, N-propylpyridinium, N-butylpyridinium, N-hexylpyridinium, N-octylpyridinium, N-butyl-3-methylpyridinium, and N-butyl-4-methylpyridinium.

[0008] According to a preferred embodiment of the present invention, the anion of the ionic liquid electrolyte is at least one selected from chloride ion, bromide ion, dicyandiamide ion, bis(fluorosulfonyl)imide ion, tetramethylborate ion, acetate ion, bis(trifluoromethanesulfonyl)imide ion, hydrogen sulfate ion, dihydrogen phosphate ion, and p-toluenesulfonate ion.

[0009] According to a preferred embodiment of the present invention, the epoxy crosslinking agent is at least one selected from polyethylene glycol diglycidyl ether (PEGDGE), trimethylolpropane triglycidyl ether (TMPTGE), glycidyl methacrylate (GMA), and glycidyl etheroxypropyl cage polysilsesquioxane (POSS).

[0010] According to a preferred embodiment of the present invention, the viologen derivative electrochromic material is at least one selected from DHV, MBV, MHV, DVB, FNV, V-CF, EV, MV, Bn-pCNVio, Et-pCNVio, CNPV, AQHV, Bn-NPV, BHV, BNPV, Bn-AcPV, DAcPV, V-SCF, APV, SV, AV, CPHEV, and HERFV.

[0011] According to a preferred embodiment of the present invention, the ferrocene derivative electrode material is selected from at least one of 2-hydroxyferrocene, 1,1'-dimethylferrocene, 1,1'-bis(1-hydroxyethyl)ferrocene, ferrocene (Fc), 1-(2-trimethylaminoethyl)ferrocene chloride, 1-(2-trimethylaminoethyl)ferrocene bromide, 1-(2-trimethylaminoethyl)ferrocene iodide, 1-(2-dodecylmethylaminoethyl)ferrocene bromide, ferrocene-onium hexafluorophosphate, and 1,1'-bis(3-trimethylaminopropyl)ferrocene dichloride.

[0012] Secondly, the present invention provides an ion gel electrolyte, which is prepared by polymerization of the electrolyte composition of any of the above embodiments.

[0013] Preferably, the gel electrolyte is prepared as follows: S1. Dissolve the polymer network framework material in an organic solvent co-solvent, stir until dissolved, add the ionic liquid electrolyte, and continue stirring until homogeneous; remove the solvent by vacuum drying, and add 1,3-dioxolane, epoxy crosslinking agent, viologen derivative electrochromic material and ferrocene derivative counter electrode material to the dried polymer ionic liquid solution, and stir until a homogeneous and transparent liquid precursor solution is formed. S2. Add lithium bis(trifluoromethanesulfonyl)imide and trifluoroacetic acid to the liquid precursor solution, stir and mix evenly, and then allow to stand for polymerization to obtain the gel electrolyte.

[0014] Preferably, in S1, the organic solvent co-solvent is one or a combination of two or more of acetonitrile, methanol, ethanol, tetrahydrofuran, chloroform, dichloromethane, N,N-dimethylacrylamide, dimethyl sulfoxide, and ethyl acetate.

[0015] Preferably, in S1, the mixing conditions of 1,3-dioxolane, epoxy crosslinking agent, polymer network framework material, ionic liquid electrolyte, viologen derivative electrochromic material, and ferrocene derivative counter electrode material are: operating at 0-100℃ for 0.5-72 h in an inert gas or air atmosphere; the conditions for drying the polymer network framework material after it has been dissolved in an organic solvent co-solvent are: evaporation at 0-100℃ for 0.5-72 h.

[0016] Preferably, the operating conditions for S2 are: in an inert gas or air atmosphere, at a temperature of 0-100℃ for 0.5-72h; after adding the initiator, the conditions for static polymerization are: at 0-100℃ for 0.5-72h.

[0017] Thirdly, the present invention also relates to the application of the above-mentioned room-temperature in-situ spontaneously polymerizable ion gel electrolyte composition or ion gel electrolyte in the preparation of electrochromic devices, wherein the gel electrolyte has high ionic conductivity and excellent optical properties.

[0018] (III) Beneficial Effects This invention addresses the shortcomings of existing electrochromic gel electrolytes, such as insufficient performance, poor compatibility, and complex preparation, through innovative raw material formulation and preparation methods. It achieves significant improvements in preparation process, overall electrolyte performance, device application effects, and raw material design flexibility. Specific technical effects are as follows: 1. Improve the overall performance of the electrolyte, laying the foundation for excellent device performance. The ion gel electrolyte prepared by this invention exhibits excellent comprehensive performance: on the one hand, based on the polymer skeleton formed by in-situ ring-opening polymerization of 1,3-dioxane, an epoxy crosslinking agent is introduced to provide crosslinking points, and the polymer network framework material serves as the second network skeleton, effectively improving the mechanical strength of the electrolyte; on the other hand, an ionic liquid electrolyte is introduced, and lithium bis(trifluoromethanesulfonylimide) and trifluoroacetic acid are innovatively used for the first time as synergistic initiators, significantly improving the ionic conductivity of the electrolyte while ensuring the high optical transmittance of the electrolyte. This provides an efficient ion transport channel for the electrochromic process and ensures excellent visual clarity of the device.

[0019] 2. Optimize device application performance to meet the needs of high-end scenarios. The present invention integrates the ion gel electrolyte with viologen electrochromic material to construct an integrated electrochromic device, which effectively solves the problem of poor compatibility between gel systems and high-performance electrochromic materials in the prior art, enabling the device to achieve a breakthrough in core performance, specifically manifested in excellent cycle stability, extremely fast electrochromic response speed, high optical contrast and high coloring efficiency, and greatly improving the practical value of electrochromic devices.

[0020] 3. Flexible and customizable raw material selection allows for targeted performance control. This invention offers high flexibility and designability in raw material selection, allowing for flexible screening of components based on actual application requirements: various imidazole, pyrrolidine, or quaternary ammonium ionic liquids can be used as the ion-conducting medium; the polymer framework can be flexibly selected from materials such as polyacrylates, polyacrylamides, and polyurethanes; in particular, by precisely designing the molecular structure of the viologen electrochromic material, a high degree of matching between it and the gel electrolyte system can be achieved at the physical, chemical, and electrochemical levels, thereby enabling targeted control of key performance characteristics of the device, such as response time, optical contrast, and cycle life, to meet the specific needs of different application scenarios such as smart windows and flexible displays.

[0021] 4. Simplifies the manufacturing process and adapts to industrialization and the fabrication of complex devices. This invention overcomes the drawbacks of conventional electrochromic gel electrolytes, which rely on external energy triggers such as ultraviolet light and heating for polymerization. It provides a method for preparation that allows for spontaneous in-situ polymerization at room temperature, requiring no specialized external equipment. The polymerization and gelation process is completed simply by injecting the precursor into the device and allowing it to stand at room temperature. This process is simple to operate, environmentally friendly, and produces precursors with excellent stability. It not only reduces preparation costs but also enables uniform and reliable in-situ molding in flexible or complex structural devices, perfectly meeting the needs of industrial continuous production and large-area device manufacturing. Attached Figure Description

[0022] Figure 1 The molecular structure of the polymer network framework material that can be selected for the ionic liquid in the gel electrolyte of this invention is shown.

[0023] Figure 2 The present invention provides a single-substituted imidazolium cation structure as a selectable ionic liquid in the gel electrolyte of the present invention.

[0024] Figure 3 The present invention provides a disubstituted imidazolium cation structure as a selectable ionic liquid in the gel electrolyte of the present invention.

[0025] Figure 4 This invention provides a selectable multi-substituted imidazolium cation structure for the ionic liquid in the gel electrolyte.

[0026] Figure 5 The pyrrolidine-based cationic structure is a selectable ionic liquid in the gel electrolyte of this invention.

[0027] Figure 6 The pyridine-based cationic structure is a selectable ionic liquid in the gel electrolyte of this invention.

[0028] Figure 7 The anionic structure of the ionic liquid in the gel electrolyte of this invention is an option.

[0029] Figure 8 The molecular structure of the epoxy crosslinking agent that can be selected in the gel electrolyte of the present invention is shown.

[0030] Figure 9 The change in conductivity of the ion gel electrolyte prepared in Example 1 of this invention during spontaneous gelation at room temperature.

[0031] Figure 10 The current curve of the ion gel electrolysis prepared in Example 1 of the present invention under long-term pulse voltage.

[0032] Figure 11 The electrochemical impedance curves are those of the ion gel electrolytes prepared by in-situ polymerization and non-in-situ polymerization in Example 1 of the present invention.

[0033] Figure 12 The ultraviolet-visible transmittance spectra of the electrochromic ion gel device prepared in Example 1 of this invention under different voltages.

[0034] Figure 13 The coloring-fading kinetic curve is shown for the electrochromic ionogel device prepared in Example 1 of this invention.

[0035] Figure 14 The image shows the kinetic cycle stability curve of the electrochromic ion gel device prepared in Example 1 of this invention.

[0036] Figure 15 The image shows the kinetic cycle stability curve of the electrochromic ion gel device prepared in Example 2 of this invention.

[0037] Figure 16 The image shows the kinetic cycle stability curve of the electrochromic ion gel device prepared in Example 3 of this invention. Detailed Implementation

[0038] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] This invention provides a room-temperature in-situ spontaneously polymerizable ionogel electrolyte composition, comprising: a liquid precursor solution and an initiator; The liquid precursor solution is a homogeneous liquid comprising a polymer network framework material, an ionic liquid electrolyte, 1,3-dioxolane, an epoxy crosslinking agent, a viologen derivative electrochromic material, and a ferrocene derivative counter electrode material. The initiator is a combination of lithium bis(trifluoromethanesulfonylimide) and trifluoroacetic acid initiator; The ionic liquid electrolyte comprises cations and anions, wherein the cations are selected from at least one of monosubstituted imidazolium cations, disubstituted imidazolium cations, polysubstituted imidazolium cations, pyrrolidineium cations, pyridinium cations, and / or quaternary ammonium cations.

[0040] Polymer network framework materials such as Figure 1As shown, it can be at least one selected from polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polybutyl acrylate (PBA), polybutyl methacrylate (PBMA), polyurethane (PU), polyglycidyl methacrylate (PGMA), polyisooctyl acrylate (PEHA), polyethyl methacrylate (PEMA), polyacrylamide (PAM), polycaprolactone diol (PCL), polylauryl methacrylate (PLMA), poly(N-vinylpyrrolidone) (PVP), poly(N-isopropylacrylamide) (PNIPAN), poly(hydroxyethyl methacrylate) (PHEMA), and polypropylene glycol (PPG). Among these, PMMA has a suitable degree of polymerization of 500-2000 (this range balances support and ion transport efficiency, meeting the optical transmittance requirements of electrochromic gel electrolytes), while PEA and PEMA have a suitable degree of polymerization of 400-1800 (this degree of polymerization forms a stable network, ensuring ionic conductivity). The suitable degree of polymerization for PBA and PBMA is 300-1500 (providing strong flexibility; this degree of polymerization avoids gel stickiness while maintaining mechanical strength). The suitable degree of polymerization for PGMA is 400-1600 (containing epoxy groups that synergistically work with crosslinking agents; excessive polymerization leads to over-crosslinking, dense networks, and hinders ion migration). The suitable degree of polymerization for PLMA is 200-1200 (this degree of polymerization is conducive to forming flexible networks). The suitable degree of polymerization for PEHA is 300-1400 (the side chain is isooctyl, exhibiting strong hydrophobicity, suitable for ionic liquid systems; excessive polymerization reduces compatibility with ionic liquids). The suitable degree of polymerization for PAM is 800-3000 (this degree of polymerization ensures both liquid retention and conductivity, suitable for dual-network gel structures). The suitable degree of polymerization for PCL is 200-1000 (this degree of polymerization maintains good electrolyte toughness and conductivity; excessive polymerization leads to increased crystallinity and reduced ionic conductivity). The suitable degree of polymerization for PPG is 100-800 (it has excellent compatibility with ionic liquids, which can improve ion transport efficiency; excessive polymerization can lead to chain entanglement and affect in-situ polymerization). The suitable degree of polymerization for PVP is 600-2500 (this range aligns with its free radical solution polymerization process characteristics, balancing compatibility and ion transport efficiency). The suitable degree of polymerization for PNIPAN is 500-2000 (this range balances temperature-sensitive response and network stability). The suitable degree of polymerization for PHEMA is 400-1800 (excessive polymerization can lead to hydroxyl aggregation, network inhomogeneity, and reduced conductivity). The suitable degree of polymerization for PU is 500-2200 (this range is suitable for gel electrolyte applications requiring high mechanical strength; too low a degree of polymerization results in insufficient mechanical strength, while too high a degree of polymerization increases chain rigidity and hinders ion migration). In room temperature in-situ polymerization systems, the degree of polymerization can be controlled in the low to medium range of the above range to avoid excessively high polymerization causing slow in-situ gelation. If it is necessary to improve the mechanical strength of the gel (such as flexible devices), the degree of polymerization can be increased to the medium to high range.If priority is given to ionic conductivity (e.g., improving electrochromic response speed), the degree of polymerization is taken at the lower limit of the range; if priority is given to cycle stability (e.g., extending device lifespan), the degree of polymerization is taken at the upper limit of the range.

[0041] The cation of the ionic liquid electrolyte can be selected as a monosubstituted imidazolium with a C1-C12 alkyl substituent at the 1-position, preferably as shown in the figure. Figure 2 At least one of the monosubstituted imidazolium cations shown: 1-methylimidazolium, 1-ethylimidazolium, 1-propylimidazolium, 1-butylimidazolium, 1-hexylimidazolium, 1-octylimidazolium, 1-decylimidazolium and 1-dodecylimidazolium.

[0042] The cation of the ionic liquid electrolyte can be selected from imidazolium, which has C1-C10 alkyl substituents independently at positions 1 and 3, respectively; preferably, it is... Figure 3 At least one of the disubstituted imidazolium ionic structures shown: 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1-propyl-3-methylimidazolium, 1-propyl-3-ethylimidazolium, 1-butyl-3-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-butyl-3-ethylimidazolium, 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-butyl-3-propylimidazolium, 1-octyl-3-methylimidazolium, 1-octyl-3-ethylimidazolium, and 1,3-octylimidazolium.

[0043] The cation of the ionic liquid electrolyte can be selected from imidazolium cations with C1-C8 alkyl substituents independently at positions 1, 2, and 3, preferably polysubstituted imidazolium cations. Figure 4 At least one of the polysubstituted imidazolium ion structures shown: 1,2,3-trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-pentyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl-2,3-dimethylimidazolium, and 1-nonyl-2,3-dimethylimidazolium.

[0044] The cation of the ionic liquid electrolyte can also be a pyrrolidineonium cation, such as a pyrrolidineonium with two C1-C6 alkyl substituents connected to N, preferably. Figure 5 At least one of the pyrrolidine-onium cations shown: N-ethyl-N-methylpyrrolidine-onium, N-propyl-N-methylpyrrolidine-onium, N-butyl-N-methylpyrrolidine-onium, N-pentyl-N-methylpyrrolidine-onium and N-hexyl-N-methylpyrrolidine-onium.

[0045] The cation of the ionic liquid electrolyte can also be a pyridinium cation, such as pyridinium with N-linked C2-C9 alkyl substituents, preferably. Figure 6 At least one of the pyridinium cations shown: N-ethylpyridinium, N-propylpyridinium, N-butylpyridinium, N-hexylpyridinium, N-octylpyridinium, N-butyl-3-methylpyridinium, and N-butyl-4-methylpyridinium.

[0046] The anion of the ionic liquid electrolyte can be selected as... Figure 7 At least one of the following: chloride ion, bromide ion, dicyandiamide ion, difluorosulfonylimide ion, tetramethylborate ion, acetate ion, bis(trifluoromethanesulfonylimide) ion, hydrogen sulfate ion, dihydrogen phosphate ion, and p-toluenesulfonate ion.

[0047] The epoxy crosslinking agent in the ion gel electrolyte composition of the present invention can be... Figure 8 At least one of the epoxy crosslinking agents shown: polyethylene glycol diglycidyl ether (PEGDGE), trimethylolpropane triglycidyl ether (TMPTGE), glycidyl methacrylate (GMA), and glycidyl etheroxypropyl cage polysilsesquioxane (POSS).

[0048] The viologen derivative electrochromic material in the ionogel electrolyte composition of the present invention is at least one selected from DHV, MBV, MHV, DVB, FNV, V-CF, EV, MV, Bn-pCNVio, Et-pCNVio, CNPV, AQHV, Bn-NPV, BHV, BNPV, Bn-AcPV, DAcPV, V-SCF, APV, SV, AV, CPHEV, and HERFV, and their structural formulas are as follows:

[0049]

[0050] The ferrocene derivative counter electrode material in the ion gel electrolyte composition of the present invention may be selected from at least one of 2-hydroxyferrocene, 1,1'-dimethylferrocene, 1,1'-bis(1-hydroxyethyl)ferrocene, ferrocene (Fc), 1-(2-trimethylaminoethyl)ferrocene chloride, 1-(2-trimethylaminoethyl)ferrocene bromide, 1-(2-trimethylaminoethyl)ferrocene iodide, 1-(2-dodecylmethylaminoethyl)ferrocene bromide, ferrocene-onium hexafluorophosphate, and 1,1'-bis(3-trimethylaminopropyl)ferrocene dichloride.

[0051] The following, in conjunction with the accompanying drawings and preferred embodiments, illustrates the room-temperature in-situ spontaneously polymerizable ionogel electrolyte for electrochromic devices proposed in this invention, its preparation method, and its applications.

[0052] Example 1 This embodiment demonstrates a typical formulation and preparation process of the ion gel electrolyte and electrochromic ion gel electrolyte described in this invention: (1) Dissolve 0.15g of polymethyl methacrylate in 5mL of tetrahydrofuran. After stirring and dissolving, add 1.0g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid. Dry under vacuum at 60°C for 8 hours to completely remove the tetrahydrofuran solvent and obtain a viscous and transparent polymer / ionic liquid composite.

[0053] (2) The polymer ionic liquid solution obtained in step (1) is mixed evenly with 0.53 g of 1,3-dioxolane, 0.20 g of glycidyl etheroxypropyl cage polysilsesquioxane, 0.05 mol / L of FNV-TFSI violite electrochromic material and 0.03 mol / L of ferrocene (Fc) counter electrode material.

[0054] (3) Add 0.215 g of lithium bis(trifluoromethanesulfonylimide) to the complex obtained in step (2) and stir at room temperature until a homogeneous, transparent liquid precursor solution is formed.

[0055] (4) Add 0.01 g of trifluoroacetic acid to the liquid precursor solution obtained in step (3), stir and mix rapidly, and degas by sonication for 2 minutes. Then inject the precursor into the test device and let it stand at room temperature of 25°C for 36 hours. The precursor spontaneously transforms into a transparent self-supporting ion gel electrolyte, named PDOL-G1.

[0056] Example 2 This embodiment demonstrates a typical formulation and preparation process of the ion gel electrolyte and electrochromic ion gel electrolyte described in this invention: (1) Dissolve 0.15g of polymethyl methacrylate in 5mL of tetrahydrofuran. After stirring and dissolving, add 1.0g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid. Dry under vacuum at 60°C for 8 hours to completely remove the tetrahydrofuran solvent and obtain a viscous and transparent polymer / ionic liquid composite.

[0057] (2) The polymer ionic liquid solution obtained in step (1) is mixed evenly with 0.53 g of 1,3-dioxolane, 0.20 g of glycidyl etheroxypropyl cage polysilsesquioxane, 0.05 mol / L of DHV-TFSI violite electrochromic material and 0.03 mol / L of ferrocene (Fc) counter electrode material.

[0058] (3) Add 0.215 g of lithium bis(trifluoromethanesulfonyl)imide salt to the complex obtained in step (2) and stir at room temperature until a homogeneous, transparent liquid precursor solution is formed.

[0059] (4) Add 0.01 g of trifluoroacetic acid to the liquid precursor solution obtained in step (3), stir and mix rapidly, and degas by sonication for 2 minutes. Then inject the precursor into the test device and let it stand at room temperature of 25°C for 36 hours. The precursor spontaneously transforms into a transparent self-supporting ion gel electrolyte, named PDOL-G2.

[0060] Example 3 This embodiment demonstrates a typical formulation and preparation process of the ion gel electrolyte and electrochromic ion gel electrolyte described in this invention: (1) Dissolve 0.15g of polyurethane in 5mL of tetrahydrofuran. After stirring and dissolving, add 1.0g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid. Dry under vacuum at 60°C for 8 hours to completely remove the tetrahydrofuran solvent and obtain a viscous and transparent polymer / ionic liquid composite.

[0061] (2) The polymer ionic liquid solution obtained in step (1) is mixed evenly with 0.53 g of 1,3-dioxolane, 0.20 g of glycidyl etheroxypropyl cage polysilsesquioxane, 0.05 mol / L of FNV-TFSI violite electrochromic material and 0.03 mol / L of ferrocene (Fc) counter electrode material.

[0062] (3) Add 0.215 g of lithium bis(trifluoromethanesulfonylimide) to the complex obtained in step (2) and stir at room temperature until a homogeneous, transparent liquid precursor solution is formed.

[0063] (4) Add 0.01 g of trifluoroacetic acid to the liquid precursor solution obtained in step (3), stir and mix rapidly, and degas by sonication for 2 minutes. Then inject the precursor into the test device and let it stand in a ring at room temperature of 25°C for 36 hours. The precursor spontaneously transforms into a transparent self-supporting ion gel electrolyte, named PDOL-G3.

[0064] The gel electrolytes obtained in Example 1 or Example 2 were systematically characterized: the ionic conductivity changes of the ion gel precursor during the spontaneous gelation process at room temperature were monitored; the electrochemical stability of the cured ion gel electrolyte PDOL-G1 under long-term pulse voltage was tested; the interfacial impedance between the in-situ polymerized and ex-situ prepared ion gel electrolytes and the electrode was compared by electrochemical impedance spectroscopy; and the spectral characteristics, response speed, coloring efficiency, and cycle stability of the integrated electrochromic device incorporating viologen material were tested.

[0065] like Figure 9The figure shows the change curve of conductivity of PDOL-G1 during spontaneous gelation at room temperature. The results show that the conductivity first decreases and then tends to stabilize over time, with the stable point corresponding to the completion of gelation. This indicates that the gel composition of the present invention can achieve controllable and stable in-situ curing at room temperature without external energy input. In addition, the experiment also proved that the gel composition can still undergo in-situ curing even when the temperature is adjusted to 10°C.

[0066] like Figure 10 The figure shows the current curve of PDOL-G1 under long-term pulsed voltage. As can be seen from the figure, after 10,000 cycles under a continuous 1.5V pulsed voltage, the current peak value and waveform remain highly consistent, with no significant attenuation. This directly demonstrates the excellent structural and interfacial stability of the electrolyte during long-term electrochemical cycling.

[0067] like Figure 11 The figure shows the electrochemical impedance spectroscopy curves of PDOL-G1 prepared by in-situ polymerization and by non-in-situ assembly. As can be seen from the figure, the electrolyte / electrode interface impedance of the in-situ polymerized product is significantly lower than that of the non-in-situ assembled product. This is the most direct evidence of the improved interfacial contact and reduced interfacial resistance of this invention, explaining the fundamental reason for the improved device performance. The non-in-situ prepared PDOL-G1 referred to here is the product formed by a static gelation reaction after the electrolyte composition of Example 1 is mixed, followed by the transfer of the formed gel electrolyte to the test device to create an electrochromic ion gel device before this test.

[0068] like Figure 12 The figure shows the UV-Vis transmittance spectra of the electrochromic ionogel device based on PDOL-G1 electrolyte at different voltages. As can be seen from the figure, the transmittance at 390 nm (close to 0%) is lowest at 1.5V (red), and the valley value is deeper than at other voltages. The optimal operating wavelength of this electrochromic ionogel device is 390 nm, and the optimal operating voltage is 1.5V, followed by 1.3V and 1.6V. The visible light transmittance spectral lines at these two voltages basically overlap.

[0069] like Figure 13 As shown, the coloring-fading kinetics curve of the electrochromic ion gel device is presented. The data results show the coloring response time (tc=8.6s) and fading response time (tb=11s), as well as the maximum optical contrast (ΔT=83%). These experimental results quantitatively demonstrate that the device prepared in Example 1 has a fast switching speed and a high optical modulation amplitude.

[0070] like Figure 14The figure shows the kinetic cycling stability curve of the electrochromic ionogel device based on PDOL-G1 electrolyte. The results show that the electrochromic optical modulation retention rate only drops below 80% of the initial value after 6000 cycles, directly demonstrating that the device constructed based on this invention has excellent long-term operating life and reliability.

[0071] like Figure 15 The figure shows the kinetic cycling stability curves of the electrochromic ionogel device based on the PDOL-G2 electrolyte of Example 2. The results show that the electrochromic optical modulation retention rate only drops below 70% of the initial value after 2000 cycles, demonstrating that FNV-TFSI has better compatibility with this system compared to DHV-TFSI in Example 2.

[0072] like Figure 16 The figure shows the kinetic cycling stability curves of the electrochromic ionogel device based on the PDOL-G3 electrolyte of Example 3. The results show that the electrochromic optical modulation retention rate only drops below 85% of the initial value after 2000 cycles, demonstrating that FNV-TFSI has better compatibility with most systems compared to DHV-TFSI in Example 2.

[0073] It should be noted that the polymer network framework material, ionic liquid electrolyte, epoxy crosslinking agent, viologen derivative electrochromic material, and ferrocene derivative counter electrode material defined in the claims of this invention are all material categories with clear common structures, core physicochemical properties, and functional positioning. Different specific substances within the same category play the same role and have the same synergistic mechanism with other components in the room temperature in-situ spontaneous polymerization ionic gel electrolyte system of this invention. Moreover, after multiple experiments, the test results of the core technical indicators such as mechanical strength, ionic conductivity, optical transmittance, electrochromic response performance, and cycle stability of the ionic gel electrolyte obtained when different specific substances are applied to this system are generally consistent with the improvement effects of existing technologies, and all can achieve the technical effects of this invention. Specifically, regardless of the specific type of polymer network framework material, such as PMMA, PEA, PBA, PBMA, PU, ​​or PGMA, it possesses excellent film-forming properties, compatibility with ionic liquids, and system dispersibility. As a second network backbone, it can synergize with the polymer backbone formed by in-situ ring-opening polymerization of 1,3-dioxolane, and with the crosslinking points provided by epoxy crosslinking agents, effectively improve the mechanical strength of ion gel electrolytes and avoid problems such as brittleness and swelling of the electrolyte. In the embodiments of this invention, PMMA and PU are selected as typical representatives, and the improvement in mechanical properties of the resulting electrolytes can be extrapolated to other materials of the same category. Regardless of the type of cation (imidazolium, pyrrolidineium, pyridinium, or quaternary ammonium cation) or anion (chloride, bis(trifluoromethanesulfonyl)imide, dicyandiamide, etc.), the ionic liquid electrolytes all share the common characteristics of low vapor pressure, high ionic conductivity, and wide electrochemical window, and can all serve as ion transport media in this system, providing an efficient ion transport channel for the electrochromic process. Adjusting the length and substitution mode of the alkyl substituent in the cation and the type of anion will only adjust the ionic conductivity within a certain range, which can meet the ion transport efficiency requirements of this invention and does not affect the synergistic effect with the initiator and electrochromic material. Epoxy crosslinking agents include polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, glycidyl methacrylate, glycidyl etheroxypropyl cage polysilsesquioxane (POSS), etc., all of which contain active epoxy groups. They can form stable crosslinking points with other components in the polymerization system of this invention, effectively improving the density and stability of the polymer network, thereby optimizing the mechanical strength and dimensional stability of the electrolyte. In the embodiments of this invention, POSS is uniformly selected as a typical representative. Its crosslinking synergistic effect can be extrapolated to other epoxy crosslinking agents, all of which can achieve synergistic reinforcement with the dual network skeleton.Viologen derivative electrochromic materials, whether FNV-TFSI, DHV-TFSI, or other specific derivatives such as MBV, MHV, DVB, EV, and MV, all possess typical viologen molecular structures, reversible redox properties, and excellent electrochromic response performance. In this ion gel electrolyte system, they can all form good compatibility with ion liquid electrolytes, achieving rapid color change and recovery through the system's efficient ion transport, while maintaining high optical transmittance to ensure the visual clarity of the electrochromic device. In this embodiment of the invention, FNV-TFSI and DHV-TFSI are selected as representatives, and their electrochromic response speed, coloring efficiency, cycle life, and other properties can be extrapolated to other viologen derivatives of the same category. Ferrocene derivatives, whether ferrocene (Fc) or other derivatives such as 2-hydroxyferrocene, 1,1'-dimethylferrocene, and 1-(2-trimethylaminoethyl)ferrocene chloride, all possess good redox reversibility, electrochemical stability, and compatibility with this system. They can all serve as active materials for the counter electrode, forming redox pairings with viologen derivative electrochromic materials to ensure the reversible cycling performance of electrochromic devices. In the embodiments of this invention, ferrocene (Fc) is selected as a typical representative, and its pairing synergistic effect can be extrapolated to other ferrocene derivatives of the same category, all of which can achieve stable electrochromic cycling of the device.

[0074] The ion gel electrolyte prepared by this invention exhibits excellent comprehensive performance: on the one hand, based on the polymer skeleton formed by in-situ ring-opening polymerization of 1,3-dioxane, an epoxy crosslinking agent is introduced to provide crosslinking points, and the polymer network framework material serves as the second network skeleton, effectively improving the mechanical strength of the electrolyte; on the other hand, an ionic liquid electrolyte is introduced, and lithium bis(trifluoromethanesulfonylimide) and trifluoroacetic acid are innovatively used for the first time as synergistic initiators, significantly improving the ionic conductivity of the electrolyte while ensuring the high optical transmittance of the electrolyte. This provides an efficient ion transport channel for the electrochromic process and ensures excellent visual clarity of the device. Based on the common characteristics and consistent technical effects of the aforementioned substances of the same category, this invention provides detailed descriptions of 1-2 typical representatives for each category of substances. The preparation methods, process parameters, and test results described are directly applicable to other specific substances of the same category as defined in the claims, which is sufficient to support the feasibility and reproducibility of all technical solutions protected by the claims of this invention. It also fully reflects the core technical concept and protection scope of this invention. Based on the description of this invention, those skilled in the art can replace the typical substances in the embodiments with other substances of the same category as defined in the claims without creative effort, and prepare high-performance room temperature in-situ spontaneously polymerizing ionogel electrolytes.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions, or combinations of technical features in the above embodiments that do not conflict with each other, can be made in accordance with the manner described in the embodiments. These modifications, substitutions or combinations do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A room temperature in situ self-polymerizing ionic gel electrolyte composition, characterized in that, Comprising: a liquid precursor solution and an initiator; the liquid precursor solution is a homogeneous liquid comprising a polymer network framework material, an ionic liquid electrolyte, 1,3-dioxolane, an epoxy-based crosslinker, a viologen derivative electrochromic material, and a ferrocene derivative counter electrode material; the initiator is a combination of lithium bis-trifluoromethanesulfonimide and an initiator trifluoroacetic acid; the ionic liquid electrolyte comprises a cation and an anion, the cation is selected from at least one of imidazolium cation, pyrrolidinium cation, pyridinium cation, and or quaternary ammonium cation.

2. The room temperature in-situ self-polymerizable ionic gel electrolyte composition of claim 1, wherein, the polymer network framework material is at least one selected from PMMA, PEA, PBA, PBMA, PU, PGMA, PEHA, PEMA, PAM, PCL, PLMA, PVP, PNIPAN, PHEMA, PPG.

3. The room temperature in situ self-polymerizing ionic gel electrolyte composition of claim 1, wherein, the imidazolium cation is at least one of mono-substituted imidazolium cation selected from 1-methylimidazolium, 1-ethylimidazolium, 1-propylimidazolium, 1-butylimidazolium, 1-hexylimidazolium, 1-octylimidazolium, 1-decylimidazolium, and 1-dodecylimidazolium; or the imidazolium cation is at least one of di-substituted imidazolium cation selected from 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1-butyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-propyl-3-ethylimidazolium, 1-pentyl-3-methylimidazolium, 1-butyl-3-ethylimidazolium, 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-butyl-3-propylimidazolium, 1-octyl-3-methylimidazolium, 1-octyl-3-ethylimidazolium, and 1,3-octylimidazolium; or the imidazolium cation is at least one of multi-substituted imidazolium cation selected from 1,2,3-trimethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-pentyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl-2,3-dimethylimidazolium, and 1-nonyl-2,3-dimethylimidazolium; the pyrrolidinium cation is at least one of N-ethyl-N-methylpyrrolidinium, N-propyl-N-methylpyrrolidinium, N-butyl-N-methylpyrrolidinium, N-pentyl-N-methylpyrrolidinium, and N-hexyl-N-methylpyrrolidinium; the pyridinium cation is at least one of N-ethylpyridinium, N-propylpyridinium, N-butylpyridinium, N-hexylpyridinium, N-octylpyridinium, N-butyl-3-methylpyridinium, and N-butyl-4-methylpyridinium.

4. The room temperature in-situ self-polymerizable ionic gel electrolyte composition according to claim 1 or 3, characterized in that, the anion of the ionic liquid electrolyte is at least one of chloride, bromide, dicyanamide, bisfluorosulfonylimide, tetramethylborate, acetate, bis-trifluoromethanesulfonylimide, hydrogen sulfate, dihydrogen phosphate, and p-toluenesulfonate.

5. The room temperature in situ self-polymerizing ionogel electrolyte composition of claim 1, wherein, The epoxy crosslinking agent is at least one of polyethylene glycol diglycidyl ether (PEGDGE), trimethylolpropane triglycidyl ether (TMPTGE), glycidyl methacrylate (GMA), and glycidyl ether oxypropyl cage polyhedral oligomeric silsesquioxane (POSS); The viologen derivative electrochromic material is at least one of DHV, MBV, MHV, DVB, FNV, V-CF, EV, MV, Bn-pCNVio, Et-pCNVio, CNPV, AQHV, Bn-NPV, BHV, BNPV, Bn-AcPV, DAcPV, V-SCF, APV, SV, AV, CPHEV, and HERFV; and the ferrocene derivative counter electrode material is at least one of 2-hydroxyferrocene, 1,1'-dimethylferrocene, 1,1'-bis(1-hydroxyethyl)ferrocene, ferrocene (Fc), 1-(2-trimethylaminoethyl)ferrocenium chloride, 1-(2-trimethylaminoethyl)ferrocenium bromide, 1-(2-trimethylaminoethyl)ferrocenium iodide, 1-(2-dodecylmethylaminoethyl)ferrocenium bromide, ferrocenium hexafluorophosphate, and 1,1'-bis(3-trimethylaminopropyl)ferrocene dichloride.

6. An ionic gel electrolyte characterized by comprising: The gel electrolyte is prepared by using the room-temperature in-situ self-polymerization ionic gel electrolyte composition according to any one of claims 1-5.

7. The ionic gel electrolyte of claim 6, wherein The gel electrolyte is prepared by using the room-temperature in-situ self-polymerization ionic gel electrolyte composition according to any one of claims 1-5. S1, dissolving the polymer network framework material in an organic solvent cosolvent, stirring to dissolve, then adding an ionic liquid electrolyte, continuing to stir to mix uniformly; vacuum drying to remove the solvent, and adding 1,3-dioxolane, an epoxy crosslinking agent, a viologen derivative electrochromic material, and a ferrocene derivative counter electrode material to the dried polymer ionic liquid solution, stirring to form a uniform, transparent liquid precursor solution; S2, adding initiator lithium bistrifluoromethylsulfonylimide and initiator trifluoroacetic acid to the liquid precursor solution, stirring to mix uniformly, and then standing to polymerize, thereby obtaining the gel electrolyte.

8. The preparation method according to claim 7, characterized in that, In S1, the organic solvent cosolvent is one or a combination of two or more of acetonitrile, methanol, ethanol, tetrahydrofuran, chloroform, dichloromethane, N,N-dimethylacrylamide, dimethyl sulfoxide, and ethyl acetate.

9. The preparation method according to claim 7, characterized in that, In S1, the mixing conditions of 1,3-dioxolane, the epoxy crosslinking agent, the polymer network framework material, the ionic liquid electrolyte, the viologen derivative electrochromic material, and the ferrocene derivative counter electrode material are as follows: under an inert gas or air atmosphere, the operating temperature is 0-100°C, and the time is 0.5-72 h; after the polymer network framework material is dissolved in the organic solvent cosolvent, the drying conditions for removing the solvent are as follows: evaporation at 0-100°C for 0.5-72 h. The operating conditions of S2 are as follows: under an inert gas or air atmosphere, the temperature is 0-100°C, and the time is 0.5-72 h. After adding the initiator, the standing conditions for polymerization are as follows: 0-100°C for 0.5-72 h.

10. The use of the room-temperature in-situ spontaneously polymerizable ion gel electrolyte composition according to any one of claims 1-5 or the ion gel electrolyte prepared by the preparation method according to any one of claims 6-9 in the preparation of electrochromic devices.

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