Imidazole polymer electrolyte membrane in energy storage lithium battery and its preparation method and application

Abstract

The present invention discloses an imidazole polymer electrolyte membrane for energy storage lithium batteries, a preparation method, and applications thereof, belonging to the field of polymer electrolytes. The method comprises reacting 1-ethylimidazole with n-butyl bromide to produce 1-ethyl-3-butylimidazole bromide; reacting 1-ethyl-3-butylimidazole bromide with lithium bis(trifluoromethanesulfonyl)imide to produce 1-ethyl-3-butylimidazole bis(fluoromethanesulfonyl)imide salt; and uniformly mixing 1-ethyl-3-butylimidazole bis(fluoromethanesulfonyl)imide salt, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene, and benzoin ethyl ether, coating the mixture, and curing the mixture to produce an imidazole ionic liquid polymer electrolyte membrane. The imidazole ionic liquid polymer electrolyte membrane achieves a triple functional integration of "rigid skeleton, flexible transmission, and interface stability," significantly improving its electrical and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer electrolytes, and in particular to an imidazole polymer electrolyte membrane in an energy storage lithium battery, a preparation method and an application thereof. Background Art

[0002] With the surge in demand for high-energy-density batteries in new energy vehicles, smart wearable devices, and energy storage grids, traditional liquid lithium-ion batteries have been unable to meet application requirements due to safety hazards such as flammable and leaky electrolytes. Solid polymer electrolytes (SPE) are considered an ideal alternative due to their non-flammability, high interface compatibility, and flexible processing properties. However, the mainstream SPE system still faces the following key challenges: SPE has become a research hotspot due to its intrinsic safety, but its industrialization still faces multiple bottlenecks. Although traditional SPE represented by polyacrylonitrile (PAN) has excellent film-forming properties, its high crystallinity hinders the migration of lithium ions (ionic conductivity <10 -5 S / cm), and the rigid interface easily leads to electrode contact failure. Existing technologies can improve segment mobility through copolymerization modification, such as the introduction of polyethylene glycol monomethyl ether acrylate (PEGMEMA) flexible segments, but pure polymer systems still have defects such as low lithium ion transference number (<0.5) and difficulty in synergistic optimization of mechanical and electrochemical properties. For example, the typical PEGMEMA-PAN cross-linking system improves the conductivity to 1.3×10 -4 S / cm, but the physical contact interface between its rigid skeleton and the electrode is prone to lithium dendrite penetration, which seriously restricts the application of high-rate batteries.

[0003] Ionic liquids (ILs) are widely used in the electrochemical field due to their wide electrochemical window (>5.0 V), high thermal stability (decomposition temperature>300 °C) and liquid-like ion transport properties (conductivity 10 -3 ~10 -2 S / cm), providing a new path to break through the above bottleneck. Studies have shown that fluorine-containing anion ILs can participate in the construction of a stable LiF-rich SEI (Solid Electrolyte Interface) layer, inhibiting dendrite growth, such as FSI - The plasticizing effect of ILs can also reduce the glass transition temperature of polymers and enhance the chain mobility. However, conventional ILs face severe challenges in direct compounding: pyrrolidine ILs have poor compatibility with polymer matrices and are prone to phase separation; imidazolium cations have poor compatibility with Li +The competitive transport leads to a sharp drop in the lithium ion transfer number (<0.4); excessive addition of ILs (>60wt%) will cause the electrolyte membrane to soften and lose mechanical integrity. Summary of the Invention

[0004] This invention addresses the low lithium-ion transference number and insufficient ionic conductivity of existing polymer-based semi-solid electrolyte membranes by introducing a specifically structured imidazole ionic liquid to modify them. However, direct introduction of such ionic liquids can lead to competitive migration of cations with lithium ions, and the risk of phase separation due to poor compatibility with the polymer matrix can hinder improvements in the lithium-ion transference number and system stability. To address this conflicting issue, the present invention provides an imidazole polymer electrolyte membrane for lithium energy storage batteries, as well as its preparation method and application.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery, comprising:

[0007] 1-ethyl imidazole and n-butyl bromide are placed in an inert gas for reaction to obtain 1-ethyl 3-butyl imidazole bromide ionic liquid;

[0008] adding 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide into a first organic solvent for reaction to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid;

[0009] The precursor solution is prepared by uniformly mixing 1-ethyl-3-butyl imidazole bis(fluoromethanesulfonyl)imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether;

[0010] The precursor solution is subjected to a coating treatment, and the precursor solution is subjected to an ultraviolet light curing treatment to obtain an imidazole ionic liquid polymer electrolyte membrane.

[0011] The molar ratio of 1-ethylimidazole to n-butyl bromide is 1:(1-3).

[0012] The step of placing 1-ethylimidazole and n-butane bromide in an inert gas for reaction to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid comprises the following steps: placing 1-ethylimidazole and n-butane bromide in an inert gas at a temperature of 24 to 26° C. and stirring for 6 to 8 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid; and washing the crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid with a second organic solvent to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid; the second organic solvent comprises one or both of ethyl acetate and anhydrous ether.

[0013] The molar ratio of the bromide 1-ethyl 3-butyl imidazolium ionic liquid to lithium bis(fluoromethanesulfonyl)imide is 1:(1-3).

[0014] The first organic solvent includes one or more of anhydrous methanol, anhydrous ethanol or isopropanol.

[0015] The method of adding 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide to a first organic solvent for reaction to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid comprises the following steps: adding 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide to a first organic solvent, stirring for 8 to 10 hours for reaction, separating after the reaction to obtain a crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, and washing the crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid with liquid ether to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid.

[0016] The mass ratio of the 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bistrifluoromethanesulfonyl imide, divinylbenzene and benzoin ethyl ether is (40-60): (40-60): (40-60): (25-50): (3-8): (1-2).

[0017] The conditions for the ultraviolet curing treatment are specifically as follows: the ultraviolet light wavelength is 200-260 μm, and the illumination time is 25-30 min.

[0018] The present invention also provides an imidazole polymer electrolyte membrane for an energy storage lithium battery, which is prepared according to the above-mentioned method for preparing an imidazole polymer electrolyte membrane for an energy storage lithium battery. The structural formula of the imidazole ionic liquid in the imidazole ionic liquid polymer electrolyte membrane is:

[0019]

[0020] Among them, FSI - It is a bis(fluoromethanesulfonyl)imide anion.

[0021] The present invention also provides an application of the above-mentioned imidazole polymer electrolyte membrane in an energy storage lithium battery, wherein the imidazole ionic liquid polymer electrolyte membrane is used to prepare a semi-solid lithium battery.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The imidazole polymer electrolyte membrane in the energy storage lithium battery provided by the present invention is an imidazole ionic liquid polymer electrolyte membrane in the energy storage lithium battery obtained by ultraviolet-induced synergistic crosslinking of acrylonitrile, polyethylene glycol methyl ether methacrylate and 1-ethyl-3-butyl imidazole bisfluorosulfonyl imide salt, which realizes the triple functional integration of "rigid skeleton-flexible transmission-interface stability". At the molecular level, the introduction of 1-ethyl-3-butyl imidazole bisfluorosulfonyl imide salt realizes triple structural regulation: its rigid imidazole ring and the cyano group (-CN) of polyacrylonitrile form a stable network structure through dipole-dipole interaction, effectively inhibiting the phase separation of the ionic liquid; the long alkyl side chain undergoes van der Waals interpenetration with the ethylene oxide (EO) segment of polyethylene glycol methyl ether methacrylate to construct a continuous ion transport network. At the same time, the FSI of 1-ethyl-3-butyl imidazole bisfluorosulfonyl imide salt - TFSI anion with lithium bis(trifluoromethanesulfonyl imide) - Through dynamic hydrogen bond bridging, the degree of lithium salt dissociation is increased, significantly reducing the activation energy of ion migration. At the process level, UV-initiated polymerization technology enables acrylonitrile, polyethylene glycol methyl ether methacrylate, and 1-ethyl-3-butylimidazole bis(fluorosulfonyl)imide salt to complete three-dimensional crosslinking in a short period of time, significantly improving efficiency compared to traditional thermal curing processes (>24 hours). The entire process requires no organic solvents, achieving green and efficient preparation.

[0024] The imidazolium ionic liquid polymer electrolyte membrane of the present invention has achieved multi-dimensional performance breakthroughs: in terms of electrochemical performance, the room temperature ionic conductivity reaches 1.15×10 -4 S / cm, and through the regulation of molecular chain entanglement and cross-linking network, the tensile strength remains at 6.7MPa, and it has excellent thermal stability, decomposing only at around 450°C, avoiding the increase in impedance caused by interface debonding during high-temperature cycles; in terms of interface stability, the assembled lithium battery measured the first discharge capacity of the battery at a rate of 0.5C to be 153 mAh·g -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1This is the H NMR (Nuclear Magnetic Resonance Spectroscopy of Hydrogen) spectrum of the 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid prepared in Example 1;

[0027] Figure 2 This is a Fourier transform infrared spectrum of the imidazole polymer electrolyte membrane in the energy storage lithium battery prepared in Example 1;

[0028] Figure 3 This is a TG (thermogravimetric analysis) thermodynamic stability test chart of the imidazole polymer electrolyte membrane in the energy storage lithium battery prepared in Example 1. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In this disclosure, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0031] In the present invention, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural.

[0032] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0033] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0034] The weights of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally increased or decreased according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the mass described in the description of the embodiments of the present invention may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0035] The disclosed embodiment of the present invention provides a method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery, comprising the following steps: reacting 1-ethylimidazole and n-butyl bromide in an inert gas to obtain a 1-ethyl-3-butylimidazolium bromide ionic liquid; adding the 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bis(fluoromethanesulfonyl)imide into a first organic solvent for reaction to obtain a 1-ethyl-3-butylimidazolium bis(fluoromethanesulfonyl)imide salt ionic liquid; uniformly mixing the 1-ethyl-3-butylimidazolium bis(fluoromethanesulfonyl)imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile (AN), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), divinylbenzene (DVB), and benzoin ethyl ether to obtain a precursor solution; coating the precursor solution, and then ultraviolet curing the precursor solution to obtain an imidazole ionic liquid polymer electrolyte membrane.

[0036] In some embodiments, the molar ratio of 1-ethylimidazole to n-butyl bromide is 1:(1-3). By limiting the reaction molar ratio of 1-ethylimidazole to n-butyl bromide, a balance between the selectivity and reaction efficiency of the double-site alkylation is achieved, thereby promoting the formation of the target product and preventing the occurrence of side reactions.

[0037] In some embodiments, 1-ethylimidazole and n-butane bromide are placed in an inert gas at a temperature of 24-26 ° C and stirred for 6-8 hours to obtain a crude product, 1-ethyl 3-butyl imidazolium bromide ionic liquid, which is a viscous oily liquid. The crude product, 1-ethyl 3-butyl imidazolium bromide ionic liquid, is washed with a second organic solvent to obtain 1-ethyl 3-butyl imidazolium bromide ionic liquid. The second organic solvent includes one or both of ethyl acetate and anhydrous ether. The 1-ethyl 3-butyl imidazolium bromide ionic liquid is stored in a dynamic vacuum at room temperature for 24 hours before use.

[0038] In some embodiments, the molar ratio of 1-ethyl-3-butylimidazolium bromide ionic liquid to lithium bisfluoromethanesulfonyl imide is 1:(1-3), and the reaction conversion rate and product purity are improved by limiting the molar ratio of 1-ethyl-3-butylimidazolium bromide ionic liquid to lithium bisfluoromethanesulfonyl imide.

[0039] In some embodiments, the first organic solvent includes one or more of anhydrous methanol, anhydrous ethanol, and isopropanol; the 1-ethyl-3-butylimidazolium bromide ionic liquid reacts with lithium bis(fluoromethanesulfonyl)imide to produce lithium bromide, which has a low solubility in organic solvents and is conducive to obtaining more target products.

[0040] In some embodiments, 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide are added to a first organic solvent and stirred for 8 to 10 hours for reaction. After the reaction, separation is performed to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, and the crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid is washed with liquid ether to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid.

[0041] In some embodiments, the mass ratio of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bistrifluoromethanesulfonyl imide, divinylbenzene and benzoin ethyl ether is (40~60): (40~60): (40~60): (25~50): (3~8): (1~2).

[0042] In some embodiments, when UV curing, the UV wavelength is 200-260 μm and the exposure time is 30-40 minutes. By selecting the appropriate UV wavelength and reaction time, the reaction efficiency can be improved and the occurrence of side reactions can be reduced.

[0043] In some embodiments, a precursor solution is cast on the surface of a first film-forming mold, copper wires are placed at each corner of the first film-forming mold, and a second film-forming mold is placed on top of the copper wires to evenly spread the precursor solution. The copper wires are 2 cm long and 30 μm in diameter. The first and second film-forming molds are offset at an angle of 30°. The temperature during the coating process is 22-28°C. In this preparation method, a copper wire is placed in the middle of the film-forming mold to help maintain uniform film thickness. If a material with poor rigidity is used, the weight of the mold may affect the uniformity of the film thickness at different locations.

[0044] The imidazole ionic liquid polymer electrolyte membrane is stored in a glove box filled with argon, with water <0.1 ppm and oxygen <0.1 ppm in the glove box. The imidazole ionic liquid polymer electrolyte membrane is stored in an argon environment to avoid being affected by moisture, oxygen, etc., thereby stabilizing its performance and extending its service life.

[0045] The present invention prepares an imidazole ionic liquid polymer electrolyte membrane by the above-mentioned preparation method. The structural formula of the imidazole ionic liquid in the imidazole ionic liquid polymer electrolyte membrane is:

[0046]

[0047] Among them, FSI - It is a bis(fluoromethanesulfonyl)imide anion.

[0048] The present invention combines a rigid stabilizing imidazole ring with a flexible butyl side chain and introduces a bis(fluorosulfonyl)imide anion with strong dissociation characteristics. The constructed [EBIm][FSI] ionic liquid exerts multiple synergistic effects in the polymer matrix: its rigid imidazole ring forms a stable anchor with the cyano group (-CN) of PAN through dipole interaction, inhibiting the aggregation of the ionic liquid; the flexible alkyl chain entangles and interpenetrates with the ethylene oxide (EO) chain segment of PEGMEMA, constructing a continuous lithium ion transmission channel. At the same time, FSI - TFSI in anions and lithium salts - By forming a bridging network through dynamic hydrogen bonds, the efficiency of lithium salt dissociation is significantly improved, promoting lithium ion migration. This ionic liquid can also be preferentially reduced on the lithium metal surface, in situ forming a dense, LiF-rich interfacial protective layer that effectively inhibits lithium dendrite growth. Its thermal stability, in conjunction with the polymer cross-linking network, enables the electrolyte to maintain structural integrity over a wide temperature range. By regulating the ionic liquid content, an optimal balance of ionic conductivity, mechanical strength, and interfacial stability is achieved, providing core material support for high-safety semi-solid-state lithium batteries.

[0049] Applying the imidazole ionic liquid polymer electrolyte membrane provided by the present invention to a semi-solid lithium battery can significantly improve the discharge specific capacity of the semi-solid lithium battery.

[0050] In the following examples, unless otherwise specified, all materials used can be obtained through common channels; and the testing methods adopted are conventional methods in the art.

[0051] Example 1

[0052] 2.0 g of 1-ethylimidazole and 4.38 g of n-butane bromide were added to a beaker and stirred at 25°C under nitrogen for 6 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0053] 4.85 g of [EBIm]Br and 3.89 g of LiFSI after standing were dissolved in anhydrous methanol and stirred for 8 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0054] Weigh 2.0 g [EBIm][FSI], 2.0 g PEGMEMA, 2.0 g AN, 1.6 g LiTFSI, 0.2 g DVB, and 0.04 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0055] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0056] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with ultraviolet light (UV) with a wavelength of 250 μm for 30 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 73 -[EBIm][FSI] 25 ; PPA 73 -[EBIm][FSI] 25Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0057] The PPA prepared in this example 73 -[EBIm][FSI] 25 The 2025 model button battery was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) and the performance test was carried out: the conductivity at room temperature was measured to be 1.25×10 -4 S / cm. To detect PPA 73 -[EBIm][FSI] 25 Application in semi-solid lithium batteries, assembled into LiFePO4 / PPA 73 -[EBIm][FSI] 25 The Li / Li battery was tested for charge and discharge cycles at 60°C. The first discharge capacity of the battery was 153 mAh·g at a rate of 0.5 C. -1 .

[0058] like Figure 1 As shown, the [EBIm][FSI] prepared in this embodiment 1 H NMR spectrum, 1 H NMR (500 MHz, D2O): 8.76 (1H, C=CH-N), 7.45 (2H, N-CH=C), 4.71 (D2O), 4.15-4.19 (4H, N-CH2), 1.76-1.81 (2H, C-CH2-C), 1.32-1.39 (3H, -CH3), 1.22-1.28 (2H, C-CH2-C), 0.77-0.8 (3H, -CH3). These characteristic peaks indicate the successful preparation of [EBIm][FSI]. The H residues at every position can be identified in the NMR spectrum, and no obvious impurity peaks appear in the NMR spectrum, indicating a high purity of the product.

[0059] like Figure 2 As shown, this is the PPA prepared in this example 73 -[EBIm][FSI] 25 Infrared spectrum, 2251 cm -1 The peaks around 1650 cm are due to the typical stretching vibrations of the nitrile group (-C≡N) in PAN. -1 There is a weak peak at 1340 cm -1 The absorption peak at 1093 cm is attributed to the asymmetric stretching vibration of S=O in the sulfonimide group (SO2-N-SO2). -1 The strong peak at is attributed to PPA 73-[EBIm][FSI] 25 of COC, which can be attributed to the ion-dipole interaction with the LiTFSI anion.

[0060] like Figure 3 As shown, this is the PPA prepared in this example 73 -[EBIm][FSI] 25 Thermal stability spectrum of PPA 73 -[EBIm][FSI] 25 It has good thermal stability, with a decomposition temperature (Td) above 450°C, and significant weight loss at around 450°C, which is due to the decomposition of the polymer main chain; the higher thermal decomposition temperature can meet the working requirements of lithium metal batteries.

[0061] Example 2

[0062] 2.0 g of 1-ethylimidazole and 4.38 g of n-butane bromide were added to a beaker and stirred at 25°C under nitrogen for 6 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0063] 4.85 g of [EBIm]Br and 3.89 g of LiFSI after standing were dissolved in anhydrous methanol and stirred for 8 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0064] Weigh 1.6 g [EBIm][FSI], 2.0 g PEGMEMA, 2.0 g AN, 1.6 g LiTFSI, 0.2 g DVB, and 0.04 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0065] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0066] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with UV light with a wavelength of 250 μm for 30 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 73 -[EBIm][FSI] 20 ; PPA 73 -[EBIm][FSI] 20 Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0067] The PPA prepared in this example 73 -[EBIm][FSI] 20 The 2025 model button battery was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) and the performance test was carried out: the conductivity at room temperature was measured to be 1.54×10 -4 S / cm. To detect PPA 73 -[EBIm][FSI] 20 Application in semi-solid lithium batteries, assembled into LiFePO4 / PPA 73 -[EBIm][FSI] 20 The Li / Li battery was tested for charge and discharge cycles at 60°C. The first discharge capacity of the battery was 142 mAh g at a rate of 0.5 C. -1 .

[0068] Example 3

[0069] 2.0 g of 1-ethylimidazole and 4.38 g of n-butane bromide were added to a beaker and stirred at 25°C under nitrogen for 6 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0070] 4.85 g of [EBIm]Br and 3.89 g of LiFSI after standing were dissolved in anhydrous methanol and stirred for 8 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0071] Weigh 2.4 g [EBIm][FSI], 2.0 g PEGMEMA, 2.0 g AN, 1.6 g LiTFSI, 0.2 g DVB, and 0.04 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0072] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0073] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with UV light with a wavelength of 250 μm for 30 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 73 -[EBIm][FSI] 30 ; PPA 73 -[EBIm][FSI] 30 Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0074] The PPA prepared in this example 73 -[EBIm][FSI] 30 The prepared polymer electrolyte membrane is extremely soft and its mechanical strength is insufficient to support its assembly into the 2025 model button battery, making its application in semi-solid-state batteries difficult.

[0075] Example 4

[0076] 4.0 g of 1-ethylimidazole and 5.7 g of n-butane bromide were added to a beaker and stirred at 24°C under nitrogen for 6 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0077] 4.85 g of [EBIm]Br and 5.85 g of LiFSI after standing were dissolved in anhydrous ethanol and stirred for 9 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0078] Weigh 1.6 g [EBIm][FSI], 1.6 g PEGMEMA, 1.6 g AN, 1.0 g LiTFSI, 0.12 g DVB, and 0.08 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0079] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0080] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with UV light with a wavelength of 220 μm for 30 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 55 -[EBIm][FSI] 20 ; PPA 55 -[EBIm][FSI] 20 Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0081] The PPA prepared in this example 55 -[EBIm][FSI] 20 The 2025 model button battery was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) and the performance test was carried out: the conductivity at room temperature was measured to be 1.17×10 -4 S / cm. To detect PPA 55 -[EBIm][FSI] 20 Application in semi-solid lithium batteries, assembled into LiFePO4 / PPA 55 -[EBIm][FSI] 20 The Li / Li battery was tested for charge and discharge cycles at 60°C. The first discharge capacity of the battery was 155 mAh·g at a rate of 0.5 C. -1 .

[0082] Example 5

[0083] 2.0 g of 1-ethylimidazole and 5.84 g of n-butane bromide were added to a beaker and stirred at 26°C under nitrogen for 8 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0084] 4.85 g of [EBIm]Br and 7.78 g of LiFSI after standing were dissolved in isopropanol and stirred for 9 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0085] Weigh 2.4 g [EBIm][FSI], 2.4 g PEGMEMA, 2.4 g AN, 2.0 g LiTFSI, 0.32 g DVB, and 0.08 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0086] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0087] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with UV light with a wavelength of 200 μm for 28 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 45 -[EBIm][FSI] 15 ; PPA 45 -[EBIm][FSI] 15 Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0088] The PPA prepared in this example 45 -[EBIm][FSI] 15The 2025 model button battery was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) and the performance test was carried out: the conductivity at room temperature was measured to be 1.15×10 -4 S / cm. To detect PPA 45 -[EBIm][FSI] 15 Application in semi-solid lithium batteries, assembled into LiFePO4 / PPA 45 -[EBIm][FSI] 15 The Li / Li battery was tested for charge and discharge cycles at 60°C. The initial discharge capacity of the battery was 156 mAh g at a rate of 0.5C. -1 .

[0089] Example 6

[0090] 2.0 g of 1-ethylimidazole and 8.55 g of n-butane bromide were added to a beaker and stirred at 24°C under nitrogen for 7 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid was washed three times with ethyl acetate and anhydrous ether to obtain 1-ethyl-3-butylimidazolium bromide ionic liquid, which was recorded as [EBIm]Br. [EBIm]Br was stored in dynamic vacuum at room temperature for 24 hours before use.

[0091] 4.85 g of [EBIm]Br and 11.67 g of LiFSI after standing were dissolved in anhydrous ethanol and stirred for 10 hours to react. The reaction solution was separated with a separatory funnel to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid was washed with liquid ether three times to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, which was recorded as [EBIm][FSI].

[0092] Weigh 2.0 g [EBIm][FSI], 2.2 g PEGMEMA, 2.2 g AN, 1.2 g LiTFSI, 0.32 g DVB, and 0.08 g benzoin ethyl ether into a beaker and stir to mix thoroughly to obtain a precursor solution;

[0093] The precursor solution was cast on the surface of the first glass mold. A copper wire of 2 cm in length and 30 μm in diameter was placed at each corner of the first glass mold. A second glass mold was then placed on top of the copper wire. The first and second glass molds were offset at an angle of 30° to ensure that the precursor solution was evenly spread between the glass molds to the desired thickness. The temperature of the entire coating process was 22-28°C.

[0094] The glass mold covered with the precursor solution in the previous step was placed horizontally on the test bench and irradiated with UV light with a wavelength of 260 μm for 25 min to initiate the polymerization reaction. After curing, an imidazole ionic liquid polymer electrolyte membrane was obtained, which was recorded as PPA. 60 -[EBIm][FSI] 20 ; PPA 60 -[EBIm][FSI] 20 Store in an argon-filled glove box (water <0.1 ppm, oxygen <0.1 ppm).

[0095] The PPA prepared in this example 60 -[EBIm][FSI] 20 The 2025 model button battery was assembled with the positive electrode (lithium iron phosphate) and the negative electrode (metal lithium sheet) and the performance test was carried out: the conductivity at room temperature was measured to be 2.75×10 -4 S / cm. To detect PPA 60 -[EBIm][FSI] 20 Application in semi-solid lithium batteries, assembled into LiFePO4 / PPA 60 -[EBIm][FSI] 20 The Li / Li battery was tested for charge and discharge cycles at 60°C. The first discharge capacity of the battery was 135 mAh g at a rate of 0.5 C. -1 .

[0096] Comparative Example 1

[0097] Comparative Example 1 The specific steps for preparing the polymer electrolyte membrane are as follows: 10.0 g of polyvinylidene fluoride-hexafluoropropylene copolymer (Poly (vinylidene fluoride-co-hexafluoropropylene, PVDF-HFP)) and 4.0 g of LiTFSI are dissolved in 50 ml of dimethylformamide (DMF) solution, the resulting solution is cast on the surface of a glass mold, and dried in a vacuum environment at a temperature of 60 ° C for 24 hours to obtain a polymer electrolyte membrane, which is recorded as PVDF-HFP. The PVDF-HFP prepared in Comparative Example 1 is assembled into a LiFePO4 / PVDF-HFP / Li battery and the charge and discharge cycle performance is tested at 60 ° C. The conductivity of the PVDF-HFP prepared in Comparative Example 1 is measured to be 3.57×10 -5 S / cm, and the first discharge capacity of the battery was measured at a rate of 0.5 C to be 89 mAh·g -1 .

[0098] The performance improvement of the present invention is mainly attributed to the synergistic effect of the ionic liquid and the polymer matrix: compared with the high crystalline structure of traditional PVDF-HFP-based electrolytes that inhibit ion migration, the composite system of the present invention constructs a three-dimensional cross-linked network through photopolymerization, effectively reducing the regular arrangement of polymer chains. At the same time, the functional groups in the ionic liquid form dynamic interactions with the lithium salt, significantly improving the dissociation ability of the lithium salt. The rigid structural units of the ionic liquid and the polar groups of the polymer are tightly bound through intermolecular forces, which inhibits the phase separation tendency of the ionic liquid, while the interpenetration of the long-chain alkyl and flexible polymer segments forms a continuous ion transmission channel. In addition, specific anions in the ionic liquid react preferentially at the electrode interface to form a stable interfacial protective layer, which effectively inhibits the growth of lithium dendrites; the flexible segments in the polymer work synergistically with the polar groups to make the electrolyte membrane both flexible and mechanically strong. By adjusting the content of the ionic liquid, an optimal balance can be achieved between high ionic conductivity and mechanical properties, breaking through the bottleneck of the imbalance in performance of traditional electrolytes.

[0099] The endpoints and any values ​​of the ranges disclosed in the present invention 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 each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery, characterized in that: include: 1-ethyl imidazole and n-butyl bromide are placed in an inert gas for reaction to obtain 1-ethyl 3-butyl imidazole bromide ionic liquid; adding 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide into a first organic solvent for reaction to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid; The precursor solution is prepared by uniformly mixing 1-ethyl-3-butyl imidazole bis(fluoromethanesulfonyl)imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bis(trifluoromethanesulfonyl)imide, divinylbenzene and benzoin ethyl ether; The precursor solution is subjected to a coating treatment, and the precursor solution is subjected to an ultraviolet light curing treatment to obtain an imidazole ionic liquid polymer electrolyte membrane.

2. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The molar ratio of 1-ethylimidazole to n-butyl bromide is 1:(1-3).

3. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The step of placing 1-ethylimidazole and n-butyl bromide in an inert gas to react to obtain 1-ethyl 3-butyl imidazolium bromide ionic liquid is specifically as follows: placing 1-ethylimidazole and n-butane bromide in an inert gas atmosphere at a temperature of 24-26° C. and stirring for 6-8 hours to obtain a crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid; washing the crude product of 1-ethyl-3-butylimidazolium bromide ionic liquid with a second organic solvent to obtain a 1-ethyl-3-butylimidazolium bromide ionic liquid; The second organic solvent includes one or both of ethyl acetate and anhydrous ether.

4. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The molar ratio of the bromide 1-ethyl 3-butyl imidazolium ionic liquid to lithium bis(fluoromethanesulfonyl)imide is 1:(1-3).

5. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The first organic solvent includes one or more of anhydrous methanol, anhydrous ethanol or isopropanol.

6. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The 1-ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide are added to the first organic solvent for reaction to obtain the 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, specifically: 1-Ethyl-3-butylimidazolium bromide ionic liquid and lithium bisfluoromethanesulfonyl imide are added to a first organic solvent and stirred for 8 to 10 hours for reaction. After the reaction, separation is performed to obtain a crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid. The crude product of 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid is washed with liquid ether to obtain 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid.

7. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The mass ratio of the 1-ethyl-3-butylimidazolium bisfluoromethanesulfonyl imide salt ionic liquid, polyethylene glycol methyl ether methacrylate, acrylonitrile, lithium bistrifluoromethanesulfonyl imide, divinylbenzene and benzoin ethyl ether is (40-60): (40-60): (40-60): (25-50): (3-8): (1-2).

8. The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 1, wherein: The conditions of the ultraviolet curing treatment are specifically: The wavelength of ultraviolet light is 200~260 μm, and the illumination time is 25~30 min.

9. An imidazole polymer electrolyte membrane for energy storage lithium battery, characterized in that The method for preparing an imidazole polymer electrolyte membrane in an energy storage lithium battery according to any one of claims 1 to 8, wherein the structural formula of the imidazole ionic liquid in the imidazole ionic liquid polymer electrolyte membrane is: Among them, FSI - It is a bis(fluoromethanesulfonyl)imide anion.

10. Use of the imidazole polymer electrolyte membrane in an energy storage lithium battery according to claim 9, characterized in that: The imidazole-based ionic liquid polymer electrolyte membrane is used for preparing a semi-solid lithium battery.

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