A polyether-based lithium electrolyte and its preparation method

Abstract

This invention relates to the field of polyether-based lithium-ion battery electrolytes; it provides a polyether-based lithium-ion battery electrolyte and its preparation method; the invention uses polyethylene oxide and lithium bis(fluorosulfonyl)imide as the main components, combined with dynamic polyether prepolymer and polyether-shelled alumina nanoparticles, controlling the imine bond conversion rate, median particle size D50, organic shell content, and the molar ratio of lithium salt to ethylene oxide units; through anhydrous acetonitrile system slurry preparation, casting, segmented drying, and post-curing, a film-like or coating-like electrolyte is obtained, with a water content not exceeding 500 mg / kg, a total residual organic solvent content not exceeding 1000 mg / kg, and controllable viscosity and thickness, while promoting a reduction in residual epoxy value; it solves the problem of difficulty in balancing viscosity and purity in casting film formation; and is suitable for the large-scale preparation of lithium-ion battery electrolyte membranes.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery electrolyte materials, specifically to a polyether-based lithium-ion battery electrolyte and its preparation method. Background Technology

[0002] Lithium-ion battery devices are evolving towards higher safety and higher energy density, requiring electrolytes to maintain stable ion transport channels during long-term operation while preserving film continuity and dimensional stability under charge-discharge induced volume changes and stress. Polyether systems possess potential advantages due to their segment polarity and flexibility. Polyethylene oxide, in particular, is easily processed into films, making it suitable for forming film-like or coating electrolytes. However, its microstructure is sensitive to salt complexation, segment movement, and phase distribution; fluctuations in formulation and process can lead to interfacial contact degradation or localized defects. Practical applications also require electrolytes with low water content and low residual organic solvents to reduce the risk of side reactions and interfacial instability. Furthermore, it is necessary to balance viscosity control during the slurry casting process with complete film formation during subsequent drying and curing. Therefore, it is crucial to simultaneously meet the comprehensive requirements of purity, processability, and structural stability in both component design and process pathways.

[0003] Existing polyether-based electrolyte solutions often improve overall performance by increasing the lithium salt ratio, introducing inorganic fillers, or employing cross-linked networks. However, structural contradictions between processability and final purity still easily arise. For example, Chinese patent CN114976231A discloses a method for improving the ionic conductivity of polymer solid electrolytes for lithium-ion batteries, as well as the prepared solid electrolyte and battery. However, high-salt systems may still present challenges in controlling phase distribution and film uniformity during solvent casting and drying. Similarly, Chinese patent CN113471522A discloses a composite solid electrolyte, its preparation method, and its applications. However, the interfacial interaction and dispersion stability between the inorganic phase and polyether segments are significantly affected by surface chemistry. Without targeted interfacial construction, problems such as agglomeration, interfacial voids, or difficulty in completely removing residual small molecules during post-processing can easily occur, thus limiting further improvements in process window and long-term stability of film-like or coated electrolytes. Summary of the Invention

[0004] The purpose of this invention is to provide a polyether-based lithium electrolyte and its preparation method, which solves the problems of existing polyether systems in that it is difficult to simultaneously control the viscosity requirements, final water content and total residual organic solvent content during the slurry casting process, as well as the insufficient interfacial crosslinking structure during the post-curing stage.

[0005] This invention combines the dynamic characteristics of imine bonds in dynamic polyether prepolymers with the polyether shell and residual epoxy groups of polyether-shelled alumina nanoparticles, enabling the system to maintain controllable viscosity and uniform dispersion during the slurry and casting stages. During the drying and post-curing stages, the residual primary amino end groups and residual epoxy groups are used to form covalent cross-linking points at the interface through ring-opening addition reactions. Combined with the control of water content and total residual organic solvent content, the structural integrity and purity of the film or coating electrolyte are synergistically improved.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A polyether-based lithium electrolyte comprises the following components: 40-75 parts by weight of polyethylene oxide; 16-28 parts by weight of lithium bis(fluorosulfonyl)imide; and 5-25 parts by weight of dynamic polyether prepolymer, wherein the dynamic polyether prepolymer is obtained by condensation of polyether amine and terephthalaldehyde, and the imine bond conversion rate is 65.0-95.0%, wherein the imine bond conversion rate is determined by ¹H NMR.

[0008] 1-15 parts by weight of polyether-shelled alumina nanoparticles, wherein the polyether-shelled alumina nanoparticles are obtained by sequentially reacting alumina nanoparticles, (3-aminopropyl)triethoxysilane, and polyethylene glycol diglycidyl ether, and the median particle size D50 is 20-120 nm, wherein the median particle size D50 is determined by wet laser diffraction, and the organic shell content is 3.0-20.0 wt%, wherein the organic shell content is determined by thermogravimetric analysis; wherein the molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide unit in polyethylene oxide is 1:6-1:20, and the water content of the polyether-based lithium electrolyte is not higher than 500 mg / kg, wherein the water content is determined by Karl Fischer titration.

[0009] Furthermore, the dynamic polyether prepolymer is prepared through the following steps:

[0010] A1. Add 100 parts by weight of polyetheramine and 18-42 parts by weight of terephthalaldehyde to 100-400 parts by weight of anhydrous ethanol, so that the molar ratio of amino to aldehyde groups is 1.0:1-1.10:1;

[0011] A2. React at 45-70℃ for 2-8 hours under a nitrogen atmosphere;

[0012] A3. Remove ethanol and by-product water at 40-60℃ and -0.03 to -0.09 MPa for 1-4 hours;

[0013] A4. When the imine bond conversion rate is 65.0-95.0% as determined by ¹H NMR, and the system is at 25℃ and a shear rate of 10 s, -1 The dynamic polyether prepolymer was obtained when the viscosity measured under the conditions was 500-10000 mPa·s.

[0014] Furthermore, before preparing the polyether-shelled alumina nanopowder, aminosilanized alumina nanopowder is first prepared, which is achieved through the following steps:

[0015] B1. Disperse 100 parts by weight of alumina nanopowder in a mixed system of 300-1200 parts by weight of anhydrous ethanol and 10-80 parts by weight of deionized water;

[0016] B2. Add 5-30 parts by weight of (3-aminopropyl)triethoxysilane and 0.5-5.0 parts by weight of acetic acid to adjust the pH of the system to 4.5-6.0, and disperse for 20-60 min;

[0017] B3. React at 50-75℃ for 2-6 hours;

[0018] B4. Wash 2-4 times with anhydrous ethanol, each time using 3-20 mL / g of the aminosilanized alumina nanoparticles, and dry to constant weight at 60-80℃ and -0.03 to -0.09 MPa. The difference between two consecutive weighings should not exceed 0.1 wt% of the total weight.

[0019] B5. When the amount of aminosilane grafting determined by thermogravimetric analysis is 1.0-8.0 wt%, the aminosilanized alumina nanopowder is obtained.

[0020] Furthermore, the polyether-shelled alumina nanoparticles are prepared through the following steps:

[0021] C1. Disperse 100 parts by weight of aminosilanized alumina nanoparticles with an aminosilane grafting amount of 1.0-8.0 wt% in 100-600 parts by weight of anhydrous acetonitrile;

[0022] C2. Add 10-80 parts by weight of polyethylene glycol diglycidyl ether and react at 50-70°C for 2-8 hours under a nitrogen atmosphere;

[0023] C3. Wash with anhydrous acetonitrile and anhydrous ethanol 1-3 times each, with each wash using 3-20 mL / g of anhydrous acetonitrile and anhydrous ethanol, respectively. Dry to constant weight at 50-70℃ and -0.03 to -0.09 MPa. The difference between two consecutive weighings should not exceed 0.1 wt% of the total weight.

[0024] C4. When the organic shell content is 3.0-20.0 wt% and the median particle size D50 is 20-120 nm, the polyether-shelled alumina nanopowder is obtained.

[0025] Furthermore, in preparing the polyether-based lithium electrolyte, a composite electrolyte precursor is first prepared, which is achieved through the following steps:

[0026] D1. Add 100 parts by weight of dynamic polyether prepolymer, 5-60 parts by weight of polyether shelled alumina nanoparticles and 20-80 parts by weight of lithium bis(fluorosulfonyl)imide to 100-500 parts by weight of anhydrous acetonitrile.

[0027] D2. Stir at 20-45℃ for 0.5-4h under a nitrogen atmosphere;

[0028] D3. Degas for 0.5-3 hours at 40-60℃ and -0.03 to -0.09 MPa.

[0029] D4. When the water content of the system is not higher than 500 mg / kg, the water content is determined by Karl Fischer titration at 25°C and a shear rate of 10 s. -1 The composite electrolyte precursor was obtained when the viscosity measured under the specified conditions was 100-5000 mPa·s.

[0030] Furthermore, the composition includes 50-65 parts by weight of polyethylene oxide, 16-25 parts by weight of lithium bis(fluorosulfonyl)imide, 8-18 parts by weight of dynamic polyether prepolymer, and 2-8 parts by weight of polyether-shelled alumina nanoparticles.

[0031] Furthermore, the average viscosity-average molecular weight of polyethylene oxide is 200,000-1,000,000, and the average number-average molecular weight of polyetheramine is 200-600.

[0032] Furthermore, the median particle size D50 of the polyether-shelled alumina nanopowder is 30-90 nm, the organic shell content is 5.0-15.0 wt%, and when preparing the polyether-shelled alumina nanopowder, the aminosilane grafting amount of the aminosilane-coated alumina nanopowder is 1.0-5.0 wt%, and the aminosilane grafting amount is determined by thermogravimetric analysis.

[0033] Furthermore, the polyether-based lithium electrolyte is in the form of a film or coating with a thickness of 15-80 μm, and the total residual organic solvent, including acetonitrile and ethanol, has a content not exceeding 1000 mg / kg. The total residual organic solvent content is determined by headspace gas chromatography.

[0034] As a concept of this invention, a system based on polyethylene oxide and lithium bis(fluorosulfonyl)imide is adopted, and dynamic polyether prepolymer and polyether-shelled alumina nanoparticles are introduced. This is mainly used to balance the controllable viscosity of the homogeneous slurry and the requirements of low water content and low total residual organic solvent content in the final electrolyte during the casting process. The dynamic polyether prepolymer is formed by the condensation of polyether amine and terephthalaldehyde to form imine bonds. By controlling the imine bond conversion rate at 65.0-95.0%, the prepolymer provides necessary structural support in the system while retaining reversible adjustment space, which helps reduce the risk of cracking and phase separation during drying. The median particle size D50 and organic shell content of the polyether-shelled alumina nanoparticles are controlled, which can improve the dispersion stability in anhydrous acetonitrile systems. During the post-curing stage, it undergoes a ring-opening addition reaction with the residual primary amino end groups of the prepolymer, forming covalent cross-linking points at the interface, thereby improving the structural integrity of the film or coating electrolyte. Furthermore, by limiting the molar ratio of lithium bis(fluorosulfonyl)imide to ethylene oxide units, and by constraining the water content and total residual organic solvent content using Karl Fischer titration and headspace gas chromatography, the formulation and process were synergistically optimized.

[0035] This invention also discloses a method for preparing a polyether-based lithium electrolyte, comprising the following steps:

[0036] S1. Before obtaining polyether-shelled alumina nanopowder and using it to prepare a composite electrolyte precursor, the alumina nanopowder is pre-dried at 80-120℃, -0.03 to -0.09MPa for 4-12h; the polyethylene oxide is pre-dried at 60-80℃, -0.03 to -0.09MPa for 8-24h; and the lithium bis(fluorosulfonyl)imide is pre-dried at 80-120℃, -0.03 to -0.09MPa for 8-24h.

[0037] S2. Provide a pre-prepared composite electrolyte precursor, wherein the composite electrolyte precursor is a system obtained by mixing and degassing a dynamic polyether prepolymer, polyether-shelled alumina nanoparticles, and lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile.

[0038] S3. Dissolve lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile to obtain a lithium salt solution, wherein the mass fraction of lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile is 5-30 wt%.

[0039] S4. Based on the final solid system, control the amount of lithium bis(fluorosulfonyl)imide added to the composite electrolyte precursor provided in step S2, the amount of lithium bis(fluorosulfonyl)imide added to the lithium salt solution obtained in step S3, and the amount of polyethylene oxide added, so that polyethylene oxide, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether-shelled alumina nanoparticles are 40-75, 16-28, 5-25, and 1-15 parts by mass, respectively, and the molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide units in polyethylene oxide is 1:6-1:20; then add the composite electrolyte precursor provided in step S2 and polyethylene oxide to the lithium salt solution obtained in step S3, and stir at 30-60℃ for 6-24h to obtain a homogeneous slurry, wherein the water content of the homogeneous slurry is not higher than 200mg / kg and the viscosity is 200-3000mPa·s.

[0040] S5. The uniform slurry obtained in step S4 is cast onto a release substrate in a controlled environment with a relative humidity not exceeding 20%RH, and the wet film thickness is 50-300μm.

[0041] S6. First, dry at 30-50℃ for 2-8 hours, then dry at 50-80℃ and -0.03 to -0.09MPa for 8-24 hours, and continue to cure under nitrogen atmosphere at 50-70℃ and -0.03 to -0.09MPa for 1-6 hours. In the prepared polyether-based lithium electrolyte, the mass ratio of dynamic polyether prepolymer to polyether shelled alumina nanoparticles is 1:0.1-1:0.6, the dry film thickness is 15-80μm, the total residual organic solvent content is not higher than 1000mg / kg, and the water content is not higher than 500mg / kg.

[0042] Furthermore, the polyetheramine used in step A1 is a diamine-type polyetheramine, with each molecule containing two primary amino end groups, and the molar ratio of its primary amino group to the aldehyde group in terephthalaldehyde is greater than 1.00:1 and not higher than 1.10:1, so that the obtained dynamic polyether prepolymer contains residual primary amino end groups; in the post-curing stage of step S6, the residual primary amino group undergoes a ring-opening addition reaction with the residual epoxy group in the polyether shell-shelled alumina nanoparticles, forming covalent cross-linking points at the interface.

[0043] Furthermore, after the post-curing process in step S6 is completed, the residual epoxy value of the electrolyte membrane measured using the same measurement method and based on the same total solid mass is lower than the residual epoxy value of the electrolyte membrane before post-curing.

[0044] Furthermore, in step C2, a reflux condenser is configured, the temperature of the condensing medium is not higher than 10℃, and the reaction temperature is 50-70℃.

[0045] Furthermore, in step S5, the film casting is carried out in a controlled environment with a relative humidity not exceeding 20%RH.

[0046] Furthermore, the post-curing stage of step S6 is carried out under a nitrogen atmosphere.

[0047] Furthermore, the imine bond conversion rate was determined by ¹H NMR using deuterated dimethyl sulfoxide (DMSO-d6) as the solvent, according to the formula X=I C=N / (I C=N +I CHO ) × 100% calculation, where I C=N The integral of the imine proton peak in the δ 8.2–8.5 ppm range, I CHO The integral of the aldehyde matrix sub-peak in the range of δ9.9-10.2ppm is given.

[0048] Furthermore, the organic shell content and aminosilane grafting amount were determined by thermogravimetric analysis (TGA) in a nitrogen atmosphere at a heating rate of 10℃ / min to 800℃. Unmodified alumina nanopowder was used as a blank control, and the percentage of additional mass loss in the 200-700℃ range relative to the blank control was taken as the organic shell content or aminosilane grafting amount.

[0049] Furthermore, the final viscosity parameters of each step were determined by a rotational rheometer at 25°C and a shear rate of 10 s⁻¹. -1 The measurement was performed using cone-plate geometry under the given conditions.

[0050] Furthermore, the median particle size D50 was determined by laser diffraction (wet method) with deionized water as the dispersion medium; the sample was tested immediately after ultrasonic dispersion, and the deviation of D50 between two consecutive measurements was taken as the criterion for complete dispersion.

[0051] Furthermore, the moisture content of the homogeneous slurry obtained in step S4 was determined by Karl Fischer titration.

[0052] As another aspect of this invention, a preparation method based on pre-drying, degassing, and segmented drying is employed. This method is primarily used to stably obtain a uniform slurry in an anhydrous acetonitrile system and achieve film casting. Simultaneously, water content and total residual organic solvent content are used as key endpoint constraints. By controlling relative humidity and limiting the viscosity and water content of the uniform slurry under controlled conditions, an operable window is established for both wet and dry film thicknesses. Furthermore, the post-curing stage, with its insulated conditions, induces a ring-opening addition reaction between residual primary amino terminal groups and residual epoxy groups, forming covalent crosslinking points at the interface. The decrease in residual epoxy value is used as a process outcome correlation, thereby improving the structural integrity and process reproducibility of the film-like or coating-like polyether-based lithium-ion electrolyte.

[0053] Dynamic polyether prepolymers focus on providing reversible adjustment space through imine bonds, making viscosity easier to control during slurry preparation and casting, and facilitating the formation of a homogeneous slurry. Polyether-shelled alumina nanoparticles focus on improving dispersion stability in anhydrous acetonitrile and polyethylene oxide systems through the polyether shell, while retaining residual epoxy groups as interfacial reaction sites. During the post-curing stage, the residual primary amino end groups in the dynamic polyether prepolymer undergo ring-opening addition reactions with the residual epoxy groups in the polyether-shelled alumina nanoparticles, forming covalent cross-linking points at the interface. This transforms the physical contact between the inorganic phase and the polyether phase into a chemical bond, thereby improving the integrity of the membrane structure without increasing the risk of runaway during slurry preparation. The defined molar ratio of lithium bis(fluorosulfonyl)imide to ethylene oxide units in polyethylene oxide provides a stable salt complexation environment for the aforementioned interface construction, synergistically supporting the control targets for water content and total residual organic solvent content.

[0054] Beneficial technical effects

[0055] 1. By combining pre-drying, degassing, controlled relative humidity casting, and segmented drying and post-curing, and using Karl Fischer titration and headspace gas chromatography as key criteria, the water content and total residual organic solvent content are controlled simultaneously, reducing the risk of interfacial instability caused by small molecule residues.

[0056] 2. The viscosity range of the composite electrolyte precursor and the viscosity range of the homogeneous slurry are clearly defined. Combined with the anhydrous acetonitrile system and the endpoint criterion of the rotational rheometer, the process window from mixing and degassing to casting is clearer, which is conducive to forming a uniform wet film thickness and improving the consistency of repeated preparation.

[0057] 3. The residual primary amino end groups brought by diamine-type polyetheramine undergo a ring-opening addition reaction with the residual epoxy groups of polyether-shelled alumina nanoparticles during the post-curing stage, forming covalent cross-linking points at the interface. This makes the interior of the film and the interface more stable, which helps to reduce the probability of cracking and coating delamination during the drying process.

[0058] 4. The median particle size D50 and organic shell content of polyether-shelled alumina nanopowder are controlled, and its preparation process achieves repeatable modification by constraining the amount of aminosilane grafting and the residual epoxy value, thereby improving its dispersion state in the polyethylene oxide system and supporting the uniformity of the film or coating electrolyte structure. Attached Figure Description

[0059] Figure 1 The images show wide-angle X-ray diffraction patterns of Example 1 and Comparative Example 1.

[0060] Figure 2 This is the deconvolution integral peak diagram of wide-angle X-ray diffraction in Example 1.

[0061] Figure 3This is the deconvolution integral peak diagram of wide-angle X-ray diffraction for Comparative Example 1.

[0062] Figure 4 The Fourier transform infrared full spectrum of Example 1 and Comparative Example 1 are shown.

[0063] Figure 5 The images show the C=N feature window diagrams in Fourier transform infrared for Example 1 and Comparative Example 1.

[0064] Figure 6 Fourier transform infrared values ​​from 1460 to 1480 cm⁻¹ for Example 1 and Comparative Example 1 -1 Crystallization environment window diagram.

[0065] Figure 7 Thermogravimetric analysis (TGA) diagrams are shown for the polyether-shelled alumina nanopowder prepared in Example 1 and the unmodified alumina nanopowder used in Comparative Example 3.

[0066] Figure 8 The differential thermogravimetric diagrams are those of Example 1 and Comparative Example 3.

[0067] Figure 9 The X-ray photoelectron spectroscopy (N1s) high-resolution images of the polyether-shelled alumina nanopowder prepared in Example 1 and the unmodified alumina nanopowder used in Comparative Example 3 are shown.

[0068] Figure 10 High-resolution X-ray photoelectron spectroscopy (Al2p) spectra of Example 1 and Comparative Example 3.

[0069] Figure 11 The Fourier transform infrared full spectrum of Example 1 and Comparative Example 7 are shown.

[0070] Figure 12 The images show the N-H scaling window plots in Fourier transform infrared for Example 1 and Comparative Example 7.

[0071] Figure 13 The images show the Fourier transform infrared window images of secondary amines in Example 1 and Comparative Example 7.

[0072] Figure 14 The images show the epoxy window in Fourier transform infrared (FTIR) images of Example 1 and Comparative Example 7.

[0073] Figure 15 This image illustrates the macroscopic surface morphology and self-supporting state of the flexible composite solid electrolyte membrane.

[0074] Figure 16 Enlarged bright-field transmission electron microscope image of a PEO / LiFSI / dynamic polyether prepolymer / polyether-shelled Al2O3 nanoparticle composite solid electrolyte membrane.

[0075] Figure 17The images show the microstructure of the PEO / LiFSI / dynamic polyether prepolymer / polyether-shelled Al2O3 nanopowder composite solid electrolyte membrane. Figure 17 a is a high-magnification scanning electron microscope image of the surface. Figure 17 b is a cross-sectional scanning electron microscope image. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0077] The alumina nanoparticles used in Examples 1 and Comparative Examples 1-7 were all γ-alumina nanoparticles with a purity of not less than 99.0%, an original median particle size (D50) of approximately 60 nm, and a BET specific surface area of ​​approximately 120-180 m² / g; the alumina nanoparticles used in Example 2 were γ-alumina nanoparticles with a purity of not less than 99.0%, an original median particle size (D50) of approximately 35 nm, and a BET specific surface area of ​​approximately 140-220 m² / g; the alumina nanoparticles used in Example 3 were γ-alumina nanoparticles with a purity of not less than 99.0%, an original median particle size (D50) of approximately 60 nm, and a BET specific surface area of ​​approximately 120-180 m² / g. The alumina nanoparticles used in Example 4 were γ-alumina nanoparticles with a purity of not less than 99.0%, an original median particle size (D50) of approximately 50 nm, and a BET specific surface area of ​​approximately 100-180 m² / g. The alumina nanoparticles used in Comparative Example 8 were also γ-alumina nanoparticles with a purity of not less than 99.0%, an original median particle size (D50) of approximately 180 nm, and a BET specific surface area of ​​approximately 30-80 m² / g. All the alumina nanoparticles mentioned above were provided by Huai'an Qiangguo Chemical Glass Instrument Co., Ltd. The polyethylene glycol diglycidyl ether used in Examples 1-4 and Comparative Examples 1-8 were all provided by Huai'an Qiangguo Chemical Glass Instrument Co., Ltd., with an average molecular weight of approximately 400-600, an epoxy equivalent of approximately 180-300 g / eq, and a corresponding epoxy value of approximately 0.33-0.56 mol / 100g.

[0078] Example 1

[0079] S1. First, pre-dry the alumina nanopowder at 100℃ and -0.06MPa for 6h, pre-dry the polyethylene oxide at 70℃ and -0.06MPa for 12h, and pre-dry the lithium bis(fluorosulfonyl)imide at 95℃ and -0.08MPa for 12h.

[0080] The dynamic polyether prepolymer in this embodiment is prepared through the following steps:

[0081] A1. The average viscosity-average molecular weight of the polyethylene oxide in this embodiment is 600,000, and the polyetheramine in this embodiment is a diamine-type polyetheramine with an average number-average molecular weight of 400. 100 parts by weight of polyetheramine and 32.0 parts by weight of terephthalaldehyde are added to 240 parts by weight of anhydrous ethanol to make the molar ratio of primary amino groups to aldehyde groups 1.05:1, so that residual primary amino end groups are retained in the dynamic polyether prepolymer.

[0082] A2. The reaction was carried out at 58°C for 4.5 h under a nitrogen atmosphere;

[0083] A3. Then remove ethanol and by-product water at 50℃ and -0.06MPa for 2 hours;

[0084] A4. A dynamic polyether prepolymer was obtained with an imine bond conversion rate of 78.0% and a viscosity of 3200 mPa·s.

[0085] In this embodiment, aminosilanized alumina nanopowder is prepared through the following steps:

[0086] B1. Disperse 100 parts by weight of alumina nanopowder in a mixed system of 700 parts by weight of anhydrous ethanol and 35 parts by weight of deionized water;

[0087] B2. Add 14 parts by mass of (3-aminopropyl)triethoxysilane and 1.8 parts by mass of acetic acid to adjust the pH of the system to 5.2 and disperse for 35 min;

[0088] B3. React at 62℃ for 4 hours;

[0089] B4. Wash three times with anhydrous ethanol, each time using 10 mL / g, and dry to constant weight at 70℃ and -0.06 MPa. The difference between two consecutive weighings is 0.06 wt% of the total mass.

[0090] B5. Aminosilanized alumina nanoparticles were obtained, with an aminosilane grafting amount of 3.2 wt%.

[0091] In this embodiment, the polyether-shelled alumina nanopowder is prepared through the following steps:

[0092] C1. Disperse 100 parts by weight of aminosilanized alumina nanoparticles in 320 parts by weight of anhydrous acetonitrile.

[0093] C2. Add 42 parts by weight of polyethylene glycol diglycidyl ether, and react at 60°C for 5 hours under nitrogen protection with a reflux condenser and a condensing medium temperature of 8°C.

[0094] C3. Wash twice each with anhydrous acetonitrile and anhydrous ethanol, each time using 10 mL / g, and dry to constant weight at 60℃ and -0.06 MPa. The difference between two consecutive weighings is 0.05 wt% of the total mass.

[0095] C4. Polyether-shelled alumina nanopowder was obtained, with an organic shell content of 9.8 wt%, a residual epoxy value of 0.12 mol / 100 g measured on a dry basis, and a median particle size D50 of 62 nm.

[0096] The composite electrolyte precursor in this embodiment is prepared through the following steps:

[0097] D1. Add 100 parts by weight of dynamic polyether prepolymer, 46.7 parts by weight of polyether shelled alumina nanoparticles and 40.0 parts by weight of lithium bis(fluorosulfonyl)imide to 260 parts by weight of anhydrous acetonitrile;

[0098] D2. Stir at 30°C for 2 hours under a nitrogen atmosphere;

[0099] D3. Degas again at 50℃ and -0.05MPa for 1.5h;

[0100] D4. A composite electrolyte precursor was obtained with a water content of 180 mg / kg and a viscosity of 1400 mPa·s.

[0101] S2. Use the above-mentioned composite electrolyte precursor as a subsequent ingredient.

[0102] S3. Separately, lithium bis(fluorosulfonyl)imide is dissolved in anhydrous acetonitrile to prepare a lithium salt solution with a mass fraction of 16 wt%.

[0103] S4. Based on the final solid system, 15 parts by mass of the composite electrolyte precursor, which is converted into dynamic polyether prepolymer, 7 parts by mass of polyether shelled alumina nanoparticles, and 6 parts by mass of lithium bis(fluorosulfonyl)imide, and 58 parts by mass of polyethylene oxide are added to the lithium salt solution, and 16 parts by mass of lithium bis(fluorosulfonyl)imide are added. The mixture is stirred at 45°C for 12 hours to obtain a homogeneous slurry with a water content of 126 mg / kg and a viscosity of 1250 mPa·s. The molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide units in the polyethylene oxide is 1:11.20.

[0104] S5. Subsequently, the homogeneous slurry was cast onto the release substrate in a controlled environment with a relative humidity of 15%RH, resulting in a wet film thickness of 160μm. It was first dried at 40°C for 4 hours, then dried at 65°C and -0.07MPa for 12 hours, and further cured under a nitrogen atmosphere at 60°C and -0.06MPa for 3 hours to obtain a film-like polyether-based lithium electrolyte. In this embodiment, polyoxyethylene, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether shell are used. The alumina nanoparticles were 58, 22, 15, and 7 parts by mass, respectively. The mass ratio of dynamic polyether prepolymer to polyether-shelled alumina nanoparticles was 1:0.467. The dry film thickness was 45 μm. The total residual organic solvent content was 420 mg / kg, and the water content was 162 mg / kg. Using the same determination method and based on the same total solid mass, the residual epoxy value of the electrolyte membrane before post-curing was 0.011 mol / 100g, which decreased to 0.004 mol / 100g after post-curing.

[0105] Features and applicable scenarios of this embodiment: This embodiment adopts a balanced component combination of 58 / 22 / 15 / 7, with an imine bond conversion rate of 78.0%, a median particle size of 62nm for shelled alumina nanoparticles, and an organic shell content of 9.8wt%. It takes into account film formation stability, interfacial adhesion ability, and ion migration continuity, and is suitable for lithium metal batteries, quasi-solid-state soft-pack batteries, and medium-rate energy storage cells with high requirements for room temperature cycling stability.

[0106] Example 2

[0107] First, alumina nanopowder was pre-dried at 90℃ and -0.05MPa for 5 hours, polyethylene oxide was pre-dried at 65℃ and -0.05MPa for 10 hours, and lithium bis(fluorosulfonyl)imide was pre-dried at 90℃ and -0.07MPa for 10 hours. The polyethylene oxide in this embodiment has an average viscosity-average molecular weight of 350,000, and the polyetheramine in this embodiment is a diamine-type polyetheramine with an average number-average molecular weight of 360. 100 parts by weight of the polyetheramine and 36.0 parts by weight of terephthalaldehyde were added to 180 parts by weight of anhydrous ethanol, making the molar ratio of primary amino groups to aldehyde groups 1.04:1, thereby achieving dynamic polyether prepolymerization. The residual primary amino terminal groups were retained in the material. The mixture was reacted at 52℃ for 3 h under a nitrogen atmosphere, followed by removal of ethanol and byproduct water at 45℃ and -0.05 MPa for 1.5 h to obtain a dynamic polyether prepolymer with an imine bond conversion rate of 69.0% and a viscosity of 1500 mPa·s. 100 parts by weight of alumina nanoparticles were dispersed in a mixture of 550 parts by weight of anhydrous ethanol and 22 parts by weight of deionized water. 9 parts by weight of (3-aminopropyl)triethoxysilane and 1.0 part by weight of acetic acid were added to adjust the pH to 4.9, and the mixture was dispersed for 25 min. The mixture was then reacted at 56℃ for 3 h and washed twice with anhydrous ethanol. Each time, 6 mL / g of anhydrous ethanol was used, and the mixture was dried to constant weight at 65℃ and -0.05 MPa. The difference between two consecutive weighings was 0.07 wt% of the total mass, yielding aminosilanized alumina nanopowder with an aminosilane grafting amount of 2.1 wt%. 100 parts by weight of the aminosilanized alumina nanopowder were dispersed in 220 parts by weight of anhydrous acetonitrile, and 28 parts by weight of polyethylene glycol diglycidyl ether were added. The mixture was reacted at 55℃ for 3.5 h under nitrogen protection with a reflux condenser and a condensing medium temperature of 7℃. The mixture was washed once each with anhydrous acetonitrile and anhydrous ethanol, each time with a volume of 6 mL. / g, and dried to constant weight at 55℃ and -0.05MPa. The difference between two consecutive weighings was 0.07wt% of the total mass, yielding polyether-shelled alumina nanopowder with an organic shell content of 6.2wt%. The residual epoxy value measured on a dry basis was 0.08mol / 100g, and the median particle size D50 was 36nm. 100 parts by weight of dynamic polyether prepolymer, 44.4 parts by weight of polyether-shelled alumina nanopowder, and 44.4 parts by weight of lithium bis(fluorosulfonyl)imide were added to 180 parts by weight of anhydrous acetonitrile. The mixture was stirred at 25℃ for 1h under a nitrogen atmosphere, and then dried at 45℃ and -0.05MPa.Degassing at 0.4 MPa for 1 h yielded a composite electrolyte precursor with a water content of 220 mg / kg and a viscosity of 760 mPa·s. Separately, lithium bis(fluorosulfonyl)imide was dissolved in anhydrous acetonitrile to prepare a 24 wt% lithium salt solution. Based on the final solid system, the composite electrolyte was calculated as 9 parts by mass of dynamic polyether prepolymer, 4 parts by mass of polyether-shelled alumina nanoparticles, and 4 parts by mass of lithium bis(fluorosulfonyl)imide. The precursor and 53 parts by mass of polyethylene oxide were added to a lithium salt solution, and 22 parts by mass of lithium bis(fluorosulfonyl)imide were added. The mixture was stirred at 38°C for 10 h to obtain a homogeneous slurry with a water content of 148 mg / kg and a viscosity of 860 mPa·s. The molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide units in the polyethylene oxide was 1:8.66. Subsequently, the homogeneous slurry was cast in a controlled environment with a relative humidity of 10% RH. On a release substrate, the wet film thickness was 120 μm. It was first dried at 35°C for 3 h, then dried at 58°C and -0.05 MPa for 10 h, and then further cured at 55°C and -0.05 MPa for 2 h under nitrogen atmosphere protection to obtain a film-like polyether-based lithium electrolyte. In this embodiment, the mass parts of polyethylene oxide, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether-shelled alumina nanoparticles were 53, 26, 9, and 4, respectively. The mass ratio of dynamic polyether prepolymer to polyether-shelled alumina nanoparticles was 1:0.444. The dry film thickness was 30 μm, the total residual organic solvent content was 360 mg / kg, and the water content was 188 mg / kg. According to the same determination method and the same total solid mass as the benchmark, the residual epoxy value of the electrolyte film before curing was 0.008 mol / 100g, which decreased to 0.003 mol / 100g after curing. .

[0108] Features and applicable scenarios of this embodiment: This embodiment adopts a combination of high lithium salt content, low dynamic polyether prepolymer content and small particle size filler. The median particle size of the shelled alumina nanoparticles is 36nm and the organic shell content is 6.2wt%, which is beneficial to improving the mobility of polyether chain segments and the ion transport efficiency in the room temperature to low temperature range. It is suitable for lightweight batteries, portable power supplies, power tool batteries and small power batteries with high rate response requirements.

[0109] Example 3

[0110] First, alumina nanopowder was pre-dried at 115℃ and -0.08MPa for 10 hours. Then, polyethylene oxide was pre-dried at 78℃ and -0.08MPa for 20 hours. Finally, lithium bis(fluorosulfonyl)imide was pre-dried at 110℃ and -0.08MPa for 20 hours. In this embodiment, the average viscosity-average molecular weight of the polyethylene oxide was 900,000, and the polyetheramine was a diamine-type polyetheramine with an average number-average molecular weight of 580. 100 parts by weight of the polyetheramine and 22.0 parts by weight of terephthalaldehyde were added to 320 parts by weight of anhydrous ethanol, making the molar ratio of primary amino groups to aldehyde groups 1.05:1, thereby creating the dynamic polyether... The prepolymer retains residual primary amino end groups and reacts at 66℃ for 6.5 h under a nitrogen atmosphere. Ethanol and byproduct water are then removed at 58℃ and -0.08 MPa for 3 h to obtain a dynamic polyether prepolymer with an imine bond conversion rate of 90.0% and a viscosity of 6800 mPa·s. 100 parts by weight of alumina nanoparticles are dispersed in a mixture of 980 parts by weight of anhydrous ethanol and 60 parts by weight of deionized water. 24 parts by weight of (3-aminopropyl)triethoxysilane and 3.2 parts by weight of acetic acid are added to adjust the pH to 5.7, and the mixture is dispersed for 50 min. The reaction is then carried out at 70℃ for 5 h, followed by washing with anhydrous ethanol. Each time, 16 mL / g of anhydrous ethanol was used, and the mixture was dried to constant weight at 78℃ and -0.08 MPa. The difference between two consecutive weighings was 0.04 wt% of the total mass, yielding aminosilanized alumina nanopowder with an aminosilane grafting amount of 6.2 wt%. 100 parts by weight of the aminosilanized alumina nanopowder were dispersed in 480 parts by weight of anhydrous acetonitrile, and 66 parts by weight of polyethylene glycol diglycidyl ether were added. The mixture was reacted at 68℃ for 6.5 h under nitrogen protection with a reflux condenser and a condensing medium temperature of 5℃. The mixture was washed three times each with anhydrous acetonitrile and anhydrous ethanol, each time using 16 mL / g. L / g, and dried to constant weight at 68℃ and -0.08MPa, with the difference between two consecutive weighings being 0.04wt% of the total mass, yielded polyether-shelled alumina nanopowder with an organic shell content of 16.5wt%, a residual epoxy value of 0.22mol / 100g measured on a dry basis, and a median particle size D50 of 96nm; 100 parts by weight of dynamic polyether prepolymer, 52.4 parts by weight of polyether-shelled alumina nanopowder, and 33.3 parts by weight of lithium bis(fluorosulfonyl)imide were added to 380 parts by weight of anhydrous acetonitrile, stirred at 38℃ for 3h under a nitrogen atmosphere, and then dried at 55℃ and -0.08MPa.Degassing at 0.7 MPa for 2 h yielded a composite electrolyte precursor with a water content of 160 mg / kg and a viscosity of 2500 mPa·s. Separately, lithium bis(fluorosulfonyl)imide was dissolved in anhydrous acetonitrile to prepare a 12 wt% lithium salt solution. Based on the final solid system, the composite electrolyte was converted to 21 parts by mass of dynamic polyether prepolymer, 11 parts by mass of polyether-shelled alumina nanoparticles, and 7 parts by mass of lithium bis(fluorosulfonyl)imide. A precursor and 69 parts by mass of polyethylene oxide were added to a lithium salt solution, and 11 parts by mass of lithium bis(fluorosulfonyl)imide were added. The mixture was stirred at 52°C for 18 hours to obtain a homogeneous slurry with a water content of 102 mg / kg and a viscosity of 2350 mPa·s. The molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide units in the polyethylene oxide was 1:16.28. Subsequently, the homogeneous slurry was flowed in a controlled environment with a relative humidity of 18% RH. The film, with a wet film thickness of 240 μm, was first dried at 48 °C for 6 h, then dried at 75 °C and -0.08 MPa for 20 h, and subsequently cured at 68 °C and -0.07 MPa for 5 h under nitrogen atmosphere protection to obtain a film-like polyether-based lithium electrolyte. In this embodiment, the amounts of polyethylene oxide, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether-shelled alumina nanoparticles were 69, 18, and 18, respectively. In parts by weight of 21 and 11, the mass ratio of dynamic polyether prepolymer to polyether-shelled alumina nanoparticles was 1:0.524, the dry film thickness was 72 μm, the total residual organic solvent content was 580 mg / kg, and the water content was 140 mg / kg. Using the same determination method and based on the same total solid mass, the residual epoxy value of the electrolyte membrane before curing was 0.019 mol / 100g, which decreased to 0.006 mol / 100g after curing.

[0111] Features and applicable scenarios of this embodiment: This embodiment adopts a combination of high viscosity-average molecular weight polyethylene oxide, high dynamic polyether prepolymer content and high inorganic phase content. The median particle size of the shelled alumina nanoparticles is 96nm and the organic shell content is 16.5wt%, which is beneficial to improve dimensional stability, heat resistance deformation suppression ability and long-term storage stability. It is suitable for large-capacity soft-pack batteries, energy storage cells and solid or quasi-solid-state lithium battery systems in high operating temperature environments.

[0112] Example 4

[0113] First, alumina nanoparticles were pre-dried at 118℃ and -0.085MPa for 11 hours, polyethylene oxide was pre-dried at 62℃ and -0.04MPa for 9 hours, and lithium bis(fluorosulfonyl)imide was pre-dried at 88℃ and -0.085MPa for 22 hours. The polyethylene oxide in this embodiment has an average viscosity-average molecular weight of 260,000, and the polyetheramine in this embodiment is a diamine-type polyetheramine with an average number-average molecular weight of 320. 100 parts by weight of the polyetheramine and 40.0 parts by weight of terephthalaldehyde were added to 120 parts by weight of anhydrous ethanol, making the molar ratio of primary amino groups to aldehyde groups 1.05:1, thereby maintaining the properties of the dynamic polyether prepolymer. Residual primary amino terminal groups were retained, and the mixture was reacted at 68℃ for 2.5 h under a nitrogen atmosphere. Ethanol and byproduct water were then removed at 42℃ and -0.085 MPa for 1 h to obtain a dynamic polyether prepolymer with an imine bond conversion rate of 74.0% and a viscosity of 900 mPa·s. 100 parts by weight of alumina nanoparticles were dispersed in a mixture of 360 parts by weight of anhydrous ethanol and 72 parts by weight of deionized water. 8 parts by weight of (3-aminopropyl)triethoxysilane and 4.4 parts by weight of acetic acid were added to adjust the pH to 5.8. The mixture was dispersed for 55 min and reacted at 73℃ for 5.5 h. The mixture was washed four times with anhydrous ethanol each time. The dosage was 18 mL / g, and the mixture was dried to constant weight at 79℃ and -0.085 MPa. The difference between two consecutive weighings was 0.05 wt% of the total mass, yielding aminosilanized alumina nanopowder with an aminosilane grafting amount of 1.6 wt%. 100 parts by weight of the aminosilanized alumina nanopowder were dispersed in 140 parts by weight of anhydrous acetonitrile, and 36 parts by weight of polyethylene glycol diglycidyl ether were added. The mixture was reacted at 69℃ for 7.2 h under nitrogen protection with a reflux condenser and a condensing medium temperature of 6℃. The mixture was washed twice each with anhydrous acetonitrile and anhydrous ethanol, each time at a dosage of 18 mL / g, and dried at 69℃ and -0.085 MPa. The mixture was dried to constant weight at 0.085 MPa, with the difference between two consecutive weighings being 0.05 wt% of the total mass, to obtain polyether-shelled alumina nanoparticles with an organic shell content of 10.0 wt%. The residual epoxy value measured on a dry basis was 0.14 mol / 100 g, and the median particle size D50 was 52 nm. 100 parts by weight of dynamic polyether prepolymer, 20.0 parts by weight of polyether-shelled alumina nanoparticles, and 30.0 parts by weight of lithium bis(fluorosulfonyl)imide were added to 120 parts by weight of anhydrous acetonitrile. The mixture was stirred at 44 °C for 3.5 h under a nitrogen atmosphere, and then degassed at 58 °C and -0.085 MPa for 2 hours.After 5 hours, a composite electrolyte precursor was obtained with a water content of 190 mg / kg and a viscosity of 1200 mPa·s. Separately, lithium bis(fluorosulfonyl)imide was dissolved in anhydrous acetonitrile to prepare a 28 wt% lithium salt solution. Based on the final solid system, the composite electrolyte precursor, which consisted of 10 parts by mass of dynamic polyether prepolymer, 2 parts by mass of polyether-shelled alumina nanoparticles, and 3 parts by mass of lithium bis(fluorosulfonyl)imide, was combined with polyepoxy... 45 parts by mass of ethane were added to a lithium salt solution, and 21 parts by mass of lithium bis(fluorosulfonyl)imide were added as a supplement. The mixture was stirred at 58°C for 20 hours to obtain a homogeneous slurry with a water content of 92 mg / kg and a viscosity of 2100 mPa·s. The molar ratio of lithium bis(fluorosulfonyl)imide to ethylene oxide units in the polyethylene oxide was 1:7.96. Subsequently, the homogeneous slurry was cast onto a release substrate in a controlled environment with a relative humidity of 8% RH. The wet film thickness was 70 μm. It was first dried at 48℃ for 7 h, then dried at 78℃ and -0.085 MPa for 22 h, and subsequently cured under a nitrogen atmosphere at 69℃ and -0.085 MPa for 5.5 h to obtain a film-like polyether-based lithium electrolyte. In this embodiment, the components of polyethylene oxide, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether-shelled alumina nanoparticles were 45, 24, 10, and 2 parts by mass, respectively. The mass ratio of dynamic polyether prepolymer to polyether-shelled alumina nanoparticles was 1:0.200. The dry film thickness was 18 μm, the total residual organic solvent content was 260 mg / kg, and the water content was 130 mg / kg. Using the same determination method and based on the same total solid mass, the residual epoxy value of the electrolyte film before curing was 0.010 mol / 100 g, which decreased to 0.004 mol / 100 g after curing.

[0114] Features and applicable scenarios of this embodiment: This embodiment adopts a lower amount of polyethylene oxide, a lower amount of nanopowder added and an 18μm thin film solution, combined with a 28wt% lithium salt solution and a relatively compact casting thickness, taking into account the requirements of thin-layer forming and ion transport under high salt concentration. It is suitable for thin-layer batteries, stacked cells, high specific power batteries and thin-layer composite applications on the surface of separators.

[0115] Comparative Example 1: Basically the same as Example 1, except that dynamic polyether prepolymer is not added, and an equal amount of polyethylene oxide (15 parts by mass) is used instead. The total amount of polyethylene oxide is adjusted to 73 parts by mass, while the amounts of other components and preparation conditions remain unchanged.

[0116] Comparative Example 2: It is basically the same as Example 1, except that polyether-shelled alumina nanoparticles are not added, while the amounts of other components and preparation conditions remain unchanged.

[0117] Comparative Example 3: It is basically the same as Example 1, except that alumina nanoparticles without any surface modification treatment (median particle size D50 is 60 nm, determined by wet laser diffraction) are used instead of polyether shelled alumina nanoparticles. The amount used is 7 parts by mass, and the amounts of other components and preparation conditions remain unchanged.

[0118] Comparative Example 4: Basically the same as Example 1, except that the imine bond conversion rate of the dynamic polyether prepolymer was adjusted to 52.0%. Specifically, the reaction temperature in step A2 was reduced from 58°C to 40°C and the reaction time was shortened from 4.5h to 1.0h. The solvent removal conditions in step A3 remained unchanged. When the imine bond conversion rate was measured to be 52.0% by ¹H NMR, step A4 was stopped and the material was collected. The amounts of other components and preparation conditions remained unchanged.

[0119] Comparative Example 5: It is basically the same as Example 1, except that the molar ratio of lithium bis(fluorosulfonyl)imide in the homogeneous slurry to the ethylene oxide unit in the polyethylene oxide is adjusted to 1:4.5 (achieved by increasing the total amount of lithium bis(fluorosulfonyl)imide to 55 parts by mass, while the amount of polyethylene oxide remains unchanged at 58 parts by mass), and other preparation conditions remain unchanged.

[0120] Comparative Example 6: Basically the same as Example 1, except that the molar ratio of lithium bis(fluorosulfonyl)imide in the homogeneous slurry to the ethylene oxide unit in the polyethylene oxide was adjusted to 1:24 (achieved by reducing the total amount of lithium bis(fluorosulfonyl)imide to 10 parts by mass, while the amount of polyethylene oxide remained unchanged at 58 parts by mass), and other preparation conditions remained unchanged.

[0121] Comparative Example 7: It is basically the same as Example 1, except that the post-curing stage in step S6 is omitted. That is, after drying at 65°C and -0.07MPa for 12 hours, the post-curing treatment of holding at 60°C and -0.06MPa for 3 hours under nitrogen atmosphere protection is no longer performed. The electrolyte membrane is directly peeled off from the release substrate, and other preparation conditions remain unchanged.

[0122] Comparative Example 8: Basically the same as Example 1, except that the starting material alumina nanoparticles for the polyether-shelled alumina nanoparticles were replaced with alumina nanoparticles with a median particle size D50 of 180 nm (determined by wet laser diffraction). Surface modification was carried out under the same conditions as steps B1–B5 and C1–C4 in Example 1. The resulting polyether-shelled alumina nanoparticles had an organic shell content of 9.8 wt% and a median particle size D50 of 180 nm. The amounts of other components and preparation conditions remained unchanged.

[0123] Performance testing:

[0124] Experiment 1: A circular sample of a polyether-based lithium-ion electrolyte film with a diameter of 14 mm and a thickness precisely measured using a micrometer was used. Its bulk ionic conductivity within the -10 to 80 °C range was characterized by wide-temperature-range electrochemical impedance spectroscopy (EIS) to directly verify the core effect of the dynamic polyether prepolymer and polyether-shelled alumina nanoparticles synergistically inhibiting PEO crystallization and broadening the effective ion transport temperature range. Measurements were conducted in a stainless steel ion-blocking symmetric cell (SS|SPE|SS). Conductivity was calculated from the high-frequency bulk impedance Rb using σ = t / (Rb × A). 2032 coin cells were assembled entirely in a glove box with O2 and H2O ≤ 0.1 ppm. The EIS frequency range was 10 Hz. -1 ~10 6 The frequency was Hz, the amplitude was 10mV, and a test point was taken every 10℃ from -10℃ to 80℃. After each point was kept at a constant temperature for 30 minutes, data was collected. The temperature control accuracy was ±0.5℃, the film thickness error was ≤2μm, and there were no fewer than 3 parallel samples. Rb was obtained from the intercept of the high-frequency semicircle and the real axis of the Nyquist plot. The final report is the mean ± standard deviation of the conductivity at each temperature point.

[0125] Experiment 2: A Li|SPE|SS asymmetric battery was assembled using a membrane-based polyether-based lithium electrolyte. The upper limit of its anodic oxidation stability potential was evaluated using a linear sweep voltammetry method to verify that the introduction of the dynamic cross-linked network and polyether-shelled nanoparticles did not degrade the oxidation window of the PEO matrix. The effects of residual organic solvents and moisture on electrochemical purity were also investigated. The upper limit of the stability window was defined as the potential corresponding to a current density exceeding 0.1 mA / cm², using stainless steel as the working electrode and a lithium sheet as both the counter and reference electrode. The battery was assembled in a glove box and scanned from the open-circuit potential to 6.0 V (vs. Li) at a scan rate of 5 mV / s in a 25°C oven. + (Li), and perform at least three parallel measurements. Take the onset potential corresponding to the first sudden increase in oxidation current on the LSV curve, and report the mean ± standard deviation.

[0126] Experiment 3: The film-form polyether-based lithium-ion electrolyte was cut into dumbbell-shaped strips (effective segment 25mm × 5mm, thickness taken as the average of three points). Its tensile strength and elongation at break were evaluated by uniaxial stretching to fracture to verify the effect of the dynamic polyether prepolymer reversible imine crosslinking network in effectively improving self-supporting mechanical strength without sacrificing flexibility. The experiment was conducted in an environment with relative humidity ≤20%RH and 25℃ using a universal testing machine with an accuracy of 0.01N. The sample was stretched to fracture at a tensile rate of 10mm / min, with an initial gauge length of 25mm. Samples with abnormal clamp slippage were discarded, and at least 5 valid parallel samples were retained. Tensile strength was calculated as F_max / (b×t), and elongation at break was calculated as (L-L0) / L0×100%. The final report is the mean ± standard deviation.

[0127] Experiment 4: A rectangular sample (20mm × 5mm, thickness averaged at three points) of a film-like polyether-based lithium-ion electrolyte was taken. Its storage modulus E' and loss tangent tanδ in the range of -40 to 80℃ were determined by dynamic thermomechanical analysis to evaluate the crosslinking density of the dynamic polyether prepolymer and the reinforcing effect of the polyether-shelled alumina nanoparticles, verifying the synergistic achievement of high storage modulus and reversible deformation capability. Viscoelastic behavior was measured in an alternating stress field using stress-strain phase difference analysis; the tanδ peak position corresponds to the glass transition temperature Tg. The sample was mounted under relative humidity ≤20%RH conditions and heated from -40℃ to 80℃ at a rate of 3℃ / min, a frequency of 1Hz, and a strain of 0.1% to ensure it was in the linear viscoelastic region. At least three parallel measurements were performed. The mean ± standard deviation of E' at 25℃ was used to simultaneously output the complete curves of E'(T) and tanδ(T).

[0128] Experiment 5: Using a Li|polyether-based lithium electrolyte|Li symmetric battery (electrode area 1.54 cm², lithium sheet thickness 100 μm) as the test system, the interfacial stability of the electrolyte membrane to the lithium metal anode and its resistance to lithium dendrite penetration were evaluated by constant current cycling overpotential evolution. This directly verified the effectiveness of the elastic modulus and self-healing properties imparted by the dynamic imine crosslinking network in suppressing dendrite growth and interfacial failure under actual lithium cycling conditions. A stable overpotential indicates no increase in interfacial impedance, while a sudden voltage drop or rapid fluctuation in overpotential indicates dendrite penetration failure. The battery was assembled in a glove box and subjected to constant current charge-discharge cycles at 0.1 mA / cm² current density and a single cycle capacity of 0.1 mAh / cm² in a 25℃ constant temperature chamber. A sudden voltage drop or overpotential exceeding 300% of the initial value was used as the failure criterion, and at least three parallel measurements were performed. The number of cycles until failure was recorded, and the mean ± standard deviation was reported.

[0129] Experiment 6: 0.1–0.5 g of film-form polyether-based lithium electrolyte sample was dissolved in anhydrous methanol. Residual moisture and acetonitrile / ethanol content were quantitatively characterized using Karl Fischer titration and headspace gas chromatography, respectively, to verify the effectiveness of the drying and degassing processes in ensuring electrochemical purity. This directly addresses the core indicator for resolving the contradiction in electrochemical purity during solvent-based casting processes. The Karl Fischer method, based on the quantitative reaction of iodine-sulfur dioxide with water, was pre-standardized with sodium benzoate hydrate, with an endpoint sensitivity ≤10 mg / kg. For headspace gas chromatography, the sample was equilibrated at 80℃ for 30 min in a sealed headspace vial, and then the gas was injected. Separation was performed using a DB-624 column (30 m × 0.32 mm × 1.8 μm) with an FID detector and external standard method for quantification of acetonitrile and ethanol, with a detection limit ≤50 mg / kg. Both determinations were performed in at least three parallel runs, and the mean ± standard deviation was reported in mg / kg.

[0130] Figure 1The wide-angle X-ray diffraction patterns of Example 1 and Comparative Example 1 are shown. The crystallization diffraction characteristics of the two samples were compared using the wide-angle X-ray diffraction method. The basic parameter was that the scanning range covered the main crystallization region of the polyether chain segment, and the variable parameter was whether a dynamic polyether prepolymer structure was introduced. The results showed that the characteristic diffraction peaks of Example 1 at approximately 19.1° and 23.3° were significantly weakened and broadened, indicating that the crystallization of the polyether chain segment in Example 1 was suppressed. This proves that the dynamic structure design is beneficial to reducing the degree of regular packing and improving the amorphous characteristics of the system.

[0131] Figure 2 The wide-angle X-ray diffraction deconvolution integral peak pattern of Example 1 is shown. The diffraction curve of Example 1 was quantitatively analyzed by peak separation fitting method. The basic parameters are the combination fitting of amorphous background peaks and 19.1° and 23.3° crystal peaks. The variable parameters are the peak area, peak width and the crystallization contribution ratio after fitting. The results show that the amorphous contribution ratio is relatively high, the crystal peak height is low and the half-peak width is large in Example 1, indicating that the ordered crystalline region inside the sample is reduced, which further supports its low crystallinity characteristics.

[0132] Figure 3 For the wide-angle X-ray diffraction deconvolution integral peak pattern of Comparative Example 1, the same deconvolution fitting method as in Example 1 was used to analyze Comparative Example 1. The basic parameters were the same crystal peak positions and background model, and the variable parameters were crystal peak area, peak height and half-maximum width. The results showed that Comparative Example 1 had stronger and narrower crystal peaks near 19.1° and 23.3°, indicating that its polyether segments retained a high degree of regular packing and crystallinity, which can be used as a control basis for the reduction of crystallization behavior in Example 1.

[0133] Figure 4 The Fourier transform infrared full spectrum of Example 1 and Comparative Example 1 is shown. The Fourier transform infrared spectroscopy method was used to compare the absorption of the main functional groups of the two samples. The basic parameter is the normalized absorption intensity change in the full spectrum range, and the variable parameters are whether an imine structure is formed and the changes in the chain segment environment. The results show that Example 1 has a different band response in the characteristic absorption region than Comparative Example 1, indicating that the molecular structure of the sample has changed, which provides an overall basis for subsequent local window analysis.

[0134] Figure 5 The C=N feature window images in Fourier transform infrared (FTIR) for Example 1 and Comparative Example 1 are shown below. The images were magnified using Fourier transform infrared local magnification from 1635 to 1660 cm⁻¹. -1 The absorption in the vicinity was compared, with the basic parameter being the local spectral intensity after normalization and the variable parameter being the presence or absence of imine bond formation. The results showed that Example 1 exhibited a more obvious characteristic absorption in this range, while Comparative Example 1 had a very weak response, indicating that a C=N linkage structure was formed in Example 1, proving that the expected condensation reaction occurred in the system.

[0135] Figure 6 Fourier transform infrared values ​​from 1460 to 1480 cm⁻¹ for Example 1 and Comparative Example 1 -1 Crystallization environment window diagram. Fourier transform infrared local window analysis was used to analyze the environmental differences of crystallization-related chain segments, with the basic parameters ranging from 1460 to 1480 cm⁻¹. -1 The normalized absorption peak shape within the range was determined by the variable parameters being the sample chain segment stacking state and the degree of local order. The results showed that the peak shape in this range of Example 1 was gentler and the area was lower, while the peak shape in Comparative Example 1 was more concentrated. This indicates that the order of the chain segment micro-regions in Example 1 decreased, further confirming the crystallization inhibition effect.

[0136] Figure 7 shows the thermogravimetric analysis (TGA) diagrams of the polyether-shelled alumina nanopowder prepared in Example 1 and the unmodified alumina nanopowder used in Comparative Example 3. The TGA method was used to examine the weight loss behavior of the polyether-shelled alumina nanopowder and the unmodified sample. The basic parameter was the change in sample mass retention rate during temperature increase, and the variable parameter was whether or not it had a surface organic shell. The results showed that Example 1 had more obvious additional weight loss in the medium and high temperature range, indicating that there were thermally decomposable organic components on the sample surface, proving that a stable polyether organic coating layer was formed on the surface of the inorganic particles.

[0137] Figure 8 The differential thermogravimetric plots for Example 1 and Comparative Example 3 are shown. The differential thermogravimetric method was used to analyze the characteristics of the weight loss rate of the samples as a function of temperature. The basic parameters were the peak position and peak intensity of the weight loss rate in different temperature ranges, and the variable parameters were the presence of the organic layer on the sample surface and the differences in the decomposition stages. The results showed that Example 1 showed a clearer staged decomposition peak, while the change in Comparative Example 3 was weaker. This indicates that the organic shell on the surface of Example 1 has clear thermal decomposition characteristics, further supporting the success of surface modification.

[0138] Figure 9 shows the high-resolution N1s X-ray photoelectron spectroscopy (XPS) images of the polyether-shelled alumina nanopowder prepared in Example 1 and the unmodified alumina nanopowder used in Comparative Example 3. The nitrogen-containing chemical environment on the sample surface was analyzed using XPS. The basic parameters were the N1s binding energy distribution and the composition of the fitted peaks, and the variable parameters were the relative intensities of the surface imine nitrogen and amine nitrogen signals. The results showed that the N1s signal on the surface of Example 1 was stronger and the corresponding nitrogen-containing components could be distinguished, while the response of Comparative Example 3 was weaker. This indicates that an organic nitrogen-containing layer was introduced on the surface of Example 1, proving that the particle surface coating and interfacial connection were more sufficient.

[0139] Figure 10The high-resolution X-ray photoelectron spectroscopy (XPS) images of Al2p from Example 1 and Comparative Example 3 are shown. The binding energy response of aluminum on the alumina surface was analyzed using XPS. The basic parameters were the position and peak area of ​​the main Al2p peak, and the variable parameter was whether the surface was covered by an organic layer. The results showed that the Al2p signal in Example 1 was relatively weakened and showed a certain peak shape change, indicating that the aluminum-based surface was partially shielded by the outer organic shell layer, proving that the surface coating layer has a good covering effect and interface stability.

[0140] Figure 11 The Fourier transform infrared full spectrum of Example 1 and Comparative Example 7 is shown. The Fourier transform infrared method was used to compare the changes in the overall functional groups of the relevant samples before and after post-curing. The basic parameter is the normalized absorption intensity distribution over a wide spectrum, and the variable parameter is whether post-curing reaction was performed. The results show that there are significant differences between Example 1 and Comparative Example 7 in the amino and epoxy related regions, indicating that the post-curing process caused further chemical structural evolution.

[0141] Figure 12 The Fourier transform infrared (FTIR) N–H scaling window plots of Example 1 and Comparative Example 7 are compared using the Fourier transform infrared local analysis method from 3250 to 3400 cm⁻¹. -1 The absorption changes within the range were analyzed, with the basic parameters being the intensity and area of ​​the N–H related absorption peaks and the variable parameter being the degree of post-ripening reaction. The results showed that the absorption of Example 1 was more obvious in this range, indicating that more chemical environments related to the amine structure were formed after post-ripening, proving that further interfacial reactions occurred in the system.

[0142] Figure 13 The Fourier transform infrared (FTIR) window images of secondary amines in Example 1 and Comparative Example 7 are shown. The 1550-1570 cm⁻¹ region was analyzed using the Fourier transform infrared local magnification method. -1 The characteristic absorption of secondary amines within the range was determined by the basic parameters being the changes in peak intensity and peak area within that range, and the variable parameter being whether post-maturation promoted the ring-opening addition to form new C–N linkages. The results showed that the characteristic response of secondary amines in Example 1 was enhanced, while that in Comparative Example 7 was weaker, indicating that post-maturation promoted the formation of amination structures and proving that the interfacial reaction was more complete.

[0143] Figure 14 The Fourier transform infrared (FTIR) images of epoxy resin in Example 1 and Comparative Example 7 are shown below. Fourier transform infrared local window analysis was performed from 900 to 920 cm⁻¹. -1 The absorption of epoxy characteristics within the range was determined by the basic parameters being the changes in epoxy peak intensity and relative area, and the variable parameter being the residual amount of epoxy groups before and after post-curing. The results showed that the absorption in this range was significantly reduced in Example 1, while Comparative Example 7 retained a stronger epoxy characteristic, indicating that post-curing consumed more epoxy groups, proving that the ring-opening reaction proceeded effectively and the system was more fully cured.

[0144] Figure 15 This image illustrates the macroscopic surface morphology and self-supporting state of the flexible composite solid electrolyte membrane, showing that the film exhibits good flexibility and macroscopic compactness, with no obvious bubbles or pinhole defects on the surface. This is attributed to the uniform solvent evaporation (volume shrinkage of approximately 3.5:1) of the wet film (160 μm) under gradient drying (40°C to 65°C vacuum) and effective degassing. The minute undulating texture on the film surface is a natural trace of solvent evaporation convection. The post-curing process significantly reduces the residual epoxy value within the film, ensuring a uniform cross-linked network and excellent mechanical toughness, demonstrating the feasibility of this casting and heat treatment process route for preparing high-quality large-area films.

[0145] Figure 16 This is a magnified bright-field transmission electron microscope (BTEM) image of a PEO / LiFSI / dynamic polyether prepolymer / polyether-shelled Al2O3 nanoparticle composite solid electrolyte membrane. Based on the mass-thickness contrast principle, the image clearly shows a high-contrast, near-spherical solid-core γ-Al2O3 particle core, uniformly coated with a low-contrast organic shell halo. A "chemically fused" soft interface transition without a distinct phase separation layer exists between the particles and the shallow-contrast polymer matrix. This microstructure strongly demonstrates that a two-step surface modification process involving silanization and PEGylation achieves complete encapsulation of the oxide nanoparticles by the organic shell, as well as good chemical compatibility and covalent bonding between the modified layer and the polymer matrix, validating the rationality of the scheme in optimizing the inorganic-organic interface design.

[0146] Figure 17 Image a is a high-magnification surface scanning electron microscope (SEM) image of a PEO / LiFSI / dynamic polyether prepolymer / polyether-shelled Al2O3 nanoparticle composite solid electrolyte membrane. It clearly shows the outline of individual near-spherical Al2O3 nanoparticles and the tightly packed polymer matrix around them. Due to the presence of the organic shell, the particle surface exhibits obvious soft interface features and there are no debonding cracks at the interface, which proves that the chemical anchoring provided by the polyether shell effectively enhances the interfacial bonding between the filler and the matrix. Figure 17 b is a cross-sectional scanning electron microscope image of the PEO / LiFSI / dynamic polyether prepolymer / polyether-shelled Al2O3 nanoparticle composite solid electrolyte membrane, showing a dense and uniform bulk phase structure. The Al2O3 nanoparticles are uniformly distributed along the thickness direction and have no obvious sedimentation gradient, proving that the slurry viscosity control and initial drying process have achieved stable three-dimensional dispersion of the filler in three-dimensional space.

[0147] Table 1 Summary of performance of polyether-based lithium electrolyte in various examples and comparative examples

[0148] Sample number Room temperature ionic conductivity σ@25℃ (mS / cm) Tensile strength (MPa) <![CDATA[Electrochemical stability window (V vs. Li + / Li)]]> Li-symmetric cell cycle life (cycles, @0.1mA / cm²) Storage modulus E' (MPa) at 25℃ Example 1 0.42±0.02 3.8±0.2 4.85 380±15 8.5±0.4 Example 2 0.56±0.03 2.9±0.2 4.82 335±18 6.2±0.3 Example 3 0.28±0.02 5.6±0.3 4.90 415±20 14.8±0.8 Example 4 0.48±0.03 2.6±0.2 4.80 305±18 5.8±0.4 Comparative Example 1 0.22±0.02 1.8±0.2 4.62 145±12 3.2±0.3 Comparative Example 2 0.34±0.02 2.4±0.2 4.72 168±14 4.5±0.4 Comparative Example 3 0.18±0.02 2.1±0.2 4.58 122±12 5.1±0.5 Comparative Example 4 0.30±0.02 1.5±0.2 4.62 92±10 2.4±0.3 Comparative Example 5 0.12±0.01 3.2±0.3 4.50 82±10 7.8±0.6 Comparative Example 6 0.08±0.01 3.6±0.3 4.92 158±14 8.2±0.5 Comparative Example 7 0.30±0.02 1.6±0.2 4.70 105±12 3.5±0.4 Comparative Example 8 0.24±0.02 2.8±0.3 4.68 142±12 5.6±0.5

[0149] As can be seen from the performance of the examples and comparative examples in Table 1, Comparative Example 1, lacking dynamic polyether prepolymer and the reversible imine crosslinking network to inhibit PEO crystallization, exhibits significantly lower ionic conductivity and storage modulus than the examples, resulting in a sharp drop in lithium cycle life to 145 cycles. This indicates that this component is key to resolving the contradictions between "crystallization and ionic conductivity" and "insufficient mechanical strength." Comparative Example 2, lacking polyether-shelled alumina nanoparticles, lacks interfacial reinforcement and Li... + The transport auxiliary channel showed significantly worse cycle life and modulus than the examples with the same formulation. Comparative Example 3 used unmodified alumina nanoparticles, which resulted in severe agglomeration, hindering the ion transport channel and reducing the ion conductivity to 0.18 mS / cm, one of the lowest among all samples. Furthermore, the interfacial cycle life was only 122 cycles, indicating that the polyether shell is crucial for the compatibility of the filler with the PEO matrix. Comparative Example 4 showed an imine bond conversion rate of only 52.0%, an incomplete cross-linking network, a storage modulus of only 2.4 MPa, and the weakest dendrite suppression ability (92 cycles), demonstrating that setting the lower limit of conversion rate has clear mechanical significance. Comparative Examples 5 and 6 represent two directions in which the LiFSI:EO molar ratio deviates from the optimal range. The former shows that Li... + Excessive coordination leading to ion pair formation results in transport obstruction (σ as low as 0.12 mS / cm), while insufficient carrier concentration (σ only 0.08 mS / cm) both significantly reduce lithium cycle life. Comparative Example 7, omitting the post-curing step, shows no interfacial covalent cross-linking between the residual primary amine and residual epoxy groups, resulting in a tensile strength of only 1.6 MPa, a modulus of 3.5 MPa, and a lithium cycle life of 105 cycles. This demonstrates that the interfacial covalent cross-linking points formed during post-curing are indispensable for improving the overall mechanical and electrochemical stability of the system. Comparative Example 8 uses large-particle-size nanoparticles with D50 = 180 nm, leading to decreased dispersion uniformity and localized obstruction of ion transport channels, resulting in performance inferior to the examples within the specified range. In summary, all examples significantly outperform all comparative examples in terms of overall ionic conductivity, mechanical strength, electrochemical stability, and lithium cycle life, fully validating the effectiveness of the multi-component synergistic design of this invention.

[0150] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A polyether-based lithium electrolyte, characterized in that, It comprises the following components: 40-75 parts by weight of polyethylene oxide; 16-28 parts by weight of lithium bis(fluorosulfonyl)imide; and 5-25 parts by weight of dynamic polyether prepolymer, wherein the dynamic polyether prepolymer is obtained by condensation of polyether amine and terephthalaldehyde, and the imine bond conversion rate is 65.0-95.0%, wherein the imine bond conversion rate is determined by ¹H NMR. 1-15 parts by weight of polyether-shelled alumina nanoparticles, wherein the polyether-shelled alumina nanoparticles are obtained by sequentially reacting alumina nanoparticles, (3-aminopropyl)triethoxysilane, and polyethylene glycol diglycidyl ether, and the median particle size D50 is 20-120 nm, wherein the median particle size D50 is determined by wet laser diffraction, and the organic shell content is 3.0-20.0 wt%, wherein the organic shell content is determined by thermogravimetric analysis; wherein the molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide unit in polyethylene oxide is 1:6-1:20, and the water content of the polyether-based lithium electrolyte is not higher than 500 mg / kg, wherein the water content is determined by Karl Fischer titration.

2. The polyether-based lithium electrolyte according to claim 1, characterized in that, Dynamic polyether prepolymers are prepared through the following steps: A1. Add 100 parts by weight of polyetheramine and 18-42 parts by weight of terephthalaldehyde to 100-400 parts by weight of anhydrous ethanol, so that the molar ratio of amino to aldehyde groups is 1.0:1-1.10:1; A2. React at 45-70℃ for 2-8 hours under a nitrogen atmosphere; A3. Remove ethanol and by-product water at 40-60℃ and -0.03 to -0.09 MPa for 1-4 hours; A4. When the imine bond conversion rate is 65.0-95.0% as determined by ¹H NMR, and the system is at 25℃ and a shear rate of 10 s, -1 The dynamic polyether prepolymer was obtained when the viscosity measured under the conditions was 500-10000 mPa·s.

3. The polyether-based lithium electrolyte according to claim 1, characterized in that, Before preparing polyether-shelled alumina nanopowder, aminosilanized alumina nanopowder is first prepared, which is achieved through the following steps: B1. Disperse 100 parts by weight of alumina nanopowder in a mixed system of 300-1200 parts by weight of anhydrous ethanol and 10-80 parts by weight of deionized water; B2. Add 5-30 parts by weight of (3-aminopropyl)triethoxysilane and 0.5-5.0 parts by weight of acetic acid to adjust the pH of the system to 4.5-6.0, and disperse for 20-60 min; B3. React at 50-75℃ for 2-6 hours; B4. Wash 2-4 times with anhydrous ethanol, each time using 3-20 mL / g of the aminosilanized alumina nanoparticles, and dry to constant weight at 60-80℃ and -0.03 to -0.09 MPa. The difference between two consecutive weighings should not exceed 0.1 wt% of the total weight. B5. When the amount of aminosilane grafting determined by thermogravimetric analysis is 1.0-8.0 wt%, the aminosilanized alumina nanopowder is obtained.

4. The polyether-based lithium electrolyte according to claim 3, characterized in that, Polyether-shelled alumina nanoparticles are prepared through the following steps: C1. Disperse 100 parts by weight of aminosilanized alumina nanoparticles with an aminosilane grafting amount of 1.0-8.0 wt% in 100-600 parts by weight of anhydrous acetonitrile; C2. Add 10-80 parts by weight of polyethylene glycol diglycidyl ether and react at 50-70°C for 2-8 hours under a nitrogen atmosphere; C3. Wash with anhydrous acetonitrile and anhydrous ethanol 1-3 times each, with each wash using 3-20 mL / g of anhydrous acetonitrile and anhydrous ethanol, respectively. Dry to constant weight at 50-70℃ and -0.03 to -0.09 MPa. The difference between two consecutive weighings should not exceed 0.1 wt% of the total weight. C4. When the organic shell content is 3.0-20.0 wt% and the median particle size D50 is 20-120 nm, the polyether-shelled alumina nanopowder is obtained.

5. The polyether-based lithium electrolyte according to claim 1, characterized in that, In preparing polyether-based lithium-ion electrolytes, a composite electrolyte precursor is first prepared through the following steps: D1. Add 100 parts by weight of dynamic polyether prepolymer, 5-60 parts by weight of polyether shelled alumina nanoparticles and 20-80 parts by weight of lithium bis(fluorosulfonyl)imide to 100-500 parts by weight of anhydrous acetonitrile. D2. Stir at 20-45℃ for 0.5-4h under a nitrogen atmosphere; D3. Degas for 0.5-3 hours at 40-60℃ and -0.03 to -0.09 MPa. D4. When the water content of the system is not higher than 500 mg / kg, the water content is determined by Karl Fischer titration at 25°C and a shear rate of 10 s. -1 The composite electrolyte precursor was obtained when the viscosity measured under the specified conditions was 100-5000 mPa·s.

6. The polyether-based lithium electrolyte according to claim 1, characterized in that, The components are: 50-65 parts by weight of polyethylene oxide, 16-25 parts by weight of lithium bis(fluorosulfonyl)imide, 8-18 parts by weight of dynamic polyether prepolymer, and 2-8 parts by weight of polyether-shelled alumina nanoparticles.

7. The polyether-based lithium electrolyte according to claim 1, characterized in that, The average viscosity-average molecular weight of polyethylene oxide is 200,000-1,000,000, while the average number-average molecular weight of polyetheramine is 200-600.

8. The polyether-based lithium electrolyte according to claim 1, characterized in that, The median particle size D50 of the polyether-shelled alumina nanopowder is 30-90 nm, the organic shell content is 5.0-15.0 wt%, and the aminosilane grafting amount of the aminosilane-coated alumina nanopowder is 1.0-5.0 wt% during the preparation of the polyether-shelled alumina nanopowder. The aminosilane grafting amount is determined by thermogravimetric analysis.

9. The polyether-based lithium electrolyte according to claim 1, characterized in that, The polyether-based lithium electrolyte is in the form of a film or coating with a thickness of 15-80 μm. The total residual organic solvent content, including acetonitrile and ethanol, is not higher than 1000 mg / kg. The total residual organic solvent content is determined by headspace gas chromatography.

10. A method for preparing a polyether-based lithium electrolyte as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Before preparing polyether-shelled alumina nanopowder and using it to prepare a composite electrolyte precursor, the alumina nanopowder is pre-dried at 80-120℃, -0.03 to -0.09MPa for 4-12h; the polyethylene oxide is pre-dried at 60-80℃, -0.03 to -0.09MPa for 8-24h; and the lithium bis(fluorosulfonyl)imide is pre-dried at 80-120℃, -0.03 to -0.09MPa for 8-24h. S2. Provide a composite electrolyte precursor that has been prepared, wherein the composite electrolyte precursor is a system obtained by mixing and degassing a dynamic polyether prepolymer, polyether-shelled alumina nanoparticles and lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile; S3. Dissolve lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile to obtain a lithium salt solution, wherein the mass fraction of lithium bis(fluorosulfonyl)imide in anhydrous acetonitrile is 5-30 wt%. S4. Based on the final solid system, control the amount of lithium bis(fluorosulfonyl)imide added to the composite electrolyte precursor provided in step S2, the amount of lithium bis(fluorosulfonyl)imide added to the lithium salt solution obtained in step S3, and the amount of polyethylene oxide added, so that polyethylene oxide, lithium bis(fluorosulfonyl)imide, dynamic polyether prepolymer, and polyether-shelled alumina nanoparticles are 40-75, 16-28, 5-25, and 1-15 parts by mass, respectively, and the molar ratio of lithium bis(fluorosulfonyl)imide to the ethylene oxide units in polyethylene oxide is 1:6-1:20; then add the composite electrolyte precursor provided in step S2 and polyethylene oxide to the lithium salt solution obtained in step S3, and stir at 30-60℃ for 6-24h to obtain a homogeneous slurry, wherein the water content of the homogeneous slurry is not higher than 200mg / kg and the viscosity is 200-3000mPa·s; S5. The homogeneous slurry obtained in step S4 is cast onto a release substrate in a controlled environment with a relative humidity not exceeding 20%RH, and the wet film thickness is 50-300μm; S6. First, dry at 30-50℃ for 2-8 hours, then dry at 50-80℃ and -0.03 to -0.09MPa for 8-24 hours, and continue to cure under nitrogen atmosphere at 50-70℃ and -0.03 to -0.09MPa for 1-6 hours to obtain polyether-based lithium electrolyte. In the prepared polyether-based lithium electrolyte, the mass ratio of dynamic polyether prepolymer to polyether shelled alumina nanoparticles is 1:0.1-1:0.6, the dry film thickness is 15-80μm, the total residual organic solvent content is not higher than 1000mg / kg, and the water content is not higher than 500mg / kg.

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