Solid electrolyte material for lithium battery and preparation method of solid electrolyte material

Abstract

The invention belongs to the technical field of new energy materials, and particularly relates to a solid electrolyte material for a lithium battery and a preparation method thereof. The solid electrolyte material for the lithium battery is a polyurethane elastomer and consists of a polyether ion conduction soft segment and an isocyanate crosslinking hard segment, the soft segment is selected from polyether polyol and accounts for 66-90% of the total mass of the polyurethane elastomer; the hard segment is formed by reacting diisocyanate with a chain extender, and accounts for 10-34% of the total mass of the polyurethane elastomer; and the ether solvent is sealed in the soft segment phase by the polymer network. The polyurethane elastomer disclosed by the invention has high ionic conductivity, excellent mechanical property and good interface compatibility, and can be suitable for different types of lithium batteries, such as lithium ion batteries, lithium metal batteries, high-voltage lithium ion batteries and the like; and the preparation process is simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to solid electrolyte materials for lithium batteries and their preparation methods. Background Technology

[0002] With the global energy structure shifting towards cleaner energy, the new energy industry has experienced explosive growth, and lithium batteries, as the most competitive energy storage device currently available, are seeing a continuous increase in market demand. However, traditional liquid electrolyte lithium batteries have many insurmountable drawbacks.

[0003] From a safety perspective, liquid electrolytes are mostly flammable organic liquids. When batteries are subjected to external stimuli such as impact, puncture, or high temperatures, they are highly susceptible to leaks, fires, and even explosions. According to relevant statistics, numerous accidents caused by liquid lithium battery safety issues occur every year, posing a serious threat to people's lives and property.

[0004] In terms of performance, traditional liquid electrolyte lithium batteries experience electrolyte decomposition at high temperatures, leading to rapid capacity decay and a sharp decline in cycle stability. For example, in environments above 60°C, the cycle life of some liquid lithium batteries can be reduced to less than 50% of that at room temperature, making it difficult to meet the needs of electric vehicles in high-temperature summers or tropical regions, and also unable to meet the long-term operating requirements of large-scale energy storage power stations.

[0005] The emergence of solid-state electrolytes has brought hope for solving these problems. They eliminate the risk of leakage, fundamentally removing safety hazards caused by leaks; simultaneously, they exhibit high thermal stability, maintaining stable performance over a wide temperature range, and good chemical stability with low reactivity with electrode materials.

[0006] Currently developed solid electrolytes can be mainly divided into three categories:

[0007] (1) Ceramic electrolytes: such as sulfides (e.g., Li2S-P2S5), oxides (e.g., Li7La3Zr2O) 12 Electrolytes such as these have high ionic conductivity; some sulfide electrolytes can achieve a room temperature ionic conductivity of 10⁻⁶. -3 The S / cm value is above 1. However, ceramic electrolytes are brittle and easily break during processing, making it difficult to prepare large-area, thin electrolyte membranes. Moreover, the interfacial contact resistance between the electrolyte and the electrode material is high, which is not conducive to ion conduction, making large-scale production extremely difficult.

[0008] (2) Polymer electrolytes: Represented by polyethylene oxide (PEO), it has good flexibility and processability, and can be prepared into films by methods such as solution casting and melt extrusion. However, PEO has high crystallinity and low ionic conductivity at room temperature, usually below 10. -4 The S / cm ratio is insufficient to meet the high-rate charge and discharge requirements of lithium batteries. Furthermore, its poor mechanical properties mean that during battery charging and discharging, changes in electrode volume can easily lead to electrolyte membrane rupture, affecting battery cycle performance and safety.

[0009] (3) Composite electrolyte: A composite system formed by dispersing ceramic particles in a polymer matrix, which aims to combine the advantages of high ionic conductivity of ceramic electrolyte and good processability of polymer electrolyte. However, during the composite process, ceramic particles are prone to agglomeration, which leads to a decrease in the uniformity of the electrolyte. This not only affects the improvement of ionic conductivity, but also increases the interfacial impedance of the electrolyte, resulting in poor cycle stability of the battery.

[0010] The cross-linked polyether polyurethane electrolyte disclosed in Patent Document 1 (CN115693248A) improves lithium-ion conductivity to some extent by introducing polyether segments, but the tensile strength of this material is only 2-3 MPa. During battery charging and discharging, it is difficult to withstand the volume expansion and contraction of the electrode material, and it is prone to cracking, leading to battery failure.

[0011] Patent document 2 (US20230126789A1) reports a fluorinated polyurethane solid electrolyte with excellent solvent resistance, but its synthesis requires expensive fluorinated monomers, significantly increasing production costs and hindering large-scale commercial applications. Furthermore, its room-temperature ionic conductivity is only 5 × 10⁻⁶. -5 The S / cm ratio cannot meet the performance requirements for actual use of lithium batteries.

[0012] The polyurethane-ceramic composite system used in Patent Document 3 (WO2022154320A1) improves mechanical properties to some extent, but the problem of ceramic particle agglomeration is difficult to solve, which leads to a decrease in electrolyte uniformity and affects the cycle stability of the battery, resulting in a low cycle number.

[0013] Therefore, developing a solid electrolyte material for lithium batteries that combines high ionic conductivity, excellent mechanical properties, good interfacial compatibility, and controllable cost has become a key issue that urgently needs to be addressed in promoting the industrialization of solid-state lithium batteries. Summary of the Invention

[0014] The purpose of this invention is to provide a solid electrolyte material for lithium batteries with high ionic conductivity, excellent mechanical properties, good interface compatibility, and controllable cost, as well as its preparation method, thereby solving many defects of existing solid electrolyte materials.

[0015] The solid electrolyte material for lithium batteries provided by this invention is a polyurethane elastomer composed of polyether ion-conducting soft segments and isocyanate cross-linked hard segments in a solvent. Its chemical formula and structural formula are as follows:

[0016] ;

[0017] The selection and proportions of each component were optimized through extensive experimentation:

[0018] Soft segment: Selected from polyether polyols with a number average molecular weight of 2000 or higher.

[0019] The ether bonds in polyether polyols possess strong solvation capabilities, dissolving lithium salts and promoting lithium ion migration, thus providing conduction channels for lithium ions. Soft segments constitute 66-90% (preferably 80-90%) of the total mass in polyurethane elastomers, ensuring sufficient flexibility and lithium-ion conductivity. If the proportion of soft segments is too low, the material's flexibility will decrease, resulting in insufficient ion conduction channels; if the proportion is too high, it will affect the material's mechanical properties.

[0020] The polyether polyol can be polyethylene oxide. The number of repeating units in the polyethylene oxide is 20-100.

[0021] Hard segments: formed by the reaction of diisocyanate and chain extender; hard segments form physical cross-linking points in the material, giving the material certain mechanical strength and shape stability, and account for 10-34% (preferably 10-20%) of the total mass of polyurethane elastomer. By adjusting the proportion and type of hard segments, the mechanical properties of the material can be controlled to meet different application requirements.

[0022] The diisocyanate may be selected from 4,4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), etc., preferably with a purity higher than 99% and a moisture content lower than 0.03%.

[0023] Solvent: In order to encapsulate the solvent in the soft segment phase by the polymer network, ether solvents (DOL, DME, 1M LiTFSI) are used. Considering the ion conduction, electrolyte elasticity, strength and other properties, the ratio of solvent (volume) to monomer (mass) is selected to be 1-6 ml: 1 g.

[0024] This invention also provides a method for preparing the above-mentioned polyurethane elastomer, the synthesis route of which is as follows:

[0025] ;

[0026] The specific steps of the synthesis are as follows:

[0027] (1) Preparation of polymerization raw materials: The polyether polyol is vacuum dehydrated at 100-120℃ and vacuum degree of -0.095MPa to -0.099MPa for 2-4 hours. This process is used to remove water from the polyether polyol (the water content after dehydration is less than 0.05%) to avoid water reacting with diisocyanate to form urea bonds, which would affect the quality of the prepolymer; then it is cooled to 50-60℃; at the same time, diisocyanate with a purity of ≥99% and a water content of ≤0.03% is melted at 60-70℃;

[0028] (2) Copolymerization reaction: Dissolve polyether polyol in anhydrous ether electrolyte solution, stir and mix at 40-80℃ for 30-60 minutes until homogeneous, then add molten diisocyanate, and continue stirring for 15-30 minutes to mix evenly, wherein the ratio of hydroxyl groups of polyether polyol to isocyanate groups of diisocyanate is 1:1.5-4;

[0029] (3) Curing and molding: The mixed solution is used as the electrolyte to assemble the battery. 30-50 μL of the mixed solution is dropped onto the separator, and then the battery is sealed. The battery is placed in a 60°C forced-air oven to cure for 8-12 hours to obtain the in-situ polymerized polyurethane elastomer solid electrolyte.

[0030] During the curing process, the hydrogen bonding reaction between excess isocyanate and the urethane groups formed by the hydroxyl and isocyanate groups can crosslink the molecular chains and form a stable three-dimensional network structure.

[0031] The solid electrolyte material for lithium batteries provided by this invention—polyurethane elastomer—is applicable to different types of lithium batteries, such as lithium-ion batteries, lithium metal batteries, and high-voltage lithium-ion batteries.

[0032] The solid electrolyte material for lithium batteries provided by this invention—polyurethane elastomer—is applicable to various positive and negative electrode systems in lithium batteries. The positive electrode can be selected from LiFePO4, NCM811, LiCoO2, and LiNi. 0.5 Mn 1.5 Commonly used positive electrode materials include O4, while negative electrodes can be made of metallic lithium, graphite, etc. The solid electrolyte layer thickness is only 20-50 μm, and can be adjusted depending on the different electrode materials. The interfacial impedance of this lithium battery is less than 50 Ω•cm².

[0033] This invention utilizes the mechanical properties, liquid retention characteristics, and interfacial compatibility advantages of polymers to improve the room temperature ionic conductivity of polymer-based solid electrolytes; it also enhances the mechanical properties of polymer-based solid electrolytes, enabling them to withstand the problems of electrode volume changes and lithium dendrite puncture during battery charging and discharging; this is due to the electrolyte contained within, which improves the interfacial compatibility between the electrode and the electrolyte; this invention uses readily available raw materials and simple processes, enabling low-cost mass production.

[0034] The polyurethane elastomer provided by this invention has good mechanical properties, chemical stability, and corrosion resistance, which can significantly improve the safety, energy density, and cycle stability of solid-state lithium batteries and meet the needs of different application scenarios.

[0035] The polyurethane elastomer of the present invention has the following significant advantages:

[0036] (1) High ionic conductivity: The polyether segments encapsulated in the soft segment provide a smooth conduction channel for lithium ions. The interaction between the ether bonds, the liquid electrolyte, and lithium ions promotes lithium ion migration, increases the carrier concentration, and enhances the lithium ion migration ability. The room temperature ionic conductivity can reach 2.8 × 10⁻⁶. -4 -5.8×10 -4 S / cm, meeting the high-rate charging and discharging requirements of lithium batteries.

[0037] (2) Excellent mechanical properties: The cyclic chemical cross-linking points formed by isocyanate monomers endow the material with high tensile strength (4-12MPa) and good elastic recovery rate (91%-95%). This structure can effectively buffer the volume change of the electrode during charging and discharging, and avoid the rupture of the electrolyte membrane. After multiple cycle tests, the electrolyte membrane can still maintain its intact structure, ensuring the long-term stable operation of the battery.

[0038] (3) Good interfacial compatibility: Polyurethane elastomers have a certain degree of flexibility, and their molecular chains can form good contact with the electrode material surface, fill the tiny gaps on the electrode surface, and reduce the interfacial impedance (below 50Ω•cm). 2 This helps reduce the transport resistance of lithium ions at the interface, improving the battery's charge / discharge performance and cycle stability.

[0039] (4) High safety: The material is an organic liquid electrolyte sealed inside a polymer network by a non-flammable polymer material, which greatly reduces the risk of leakage and fire. At the same time, it has excellent thermal stability, with a thermal weight loss rate of less than 5% at 150℃. It can maintain stable performance even in high-temperature environments, which greatly improves the safety and reliability of lithium batteries.

[0040] (5) Low cost and easy processing: The polyether polyols and diisocyanates used are common raw materials in the chemical industry, with wide availability and low price. The preparation process is simple, without the need for complex equipment and harsh reaction conditions, and without the need to add extra battery material processing equipment. It can be directly added to the battery for in-situ polymerization, which is suitable for large-scale industrial production. Detailed Implementation

[0041] The present invention will be further described below through examples.

[0042] In the embodiments, the room temperature ionic conductivity was tested using the AC impedance method (test frequency range of 1Hz-1MHz); the tensile strength was tested using a universal testing machine (tensile rate of 50mm / min); the elastic recovery rate was tested after 10 cycles of tensile testing at 50% strain; and the cyclic performance was tested at a 0.2C ratio.

[0043] Example 1. Solid electrolyte for lithium metal batteries

[0044] Raw material preparation: Select 80g of polyoxyethylene glycol (number average molecular weight 6000), 15g of 4,4'-diphenylmethane diisocyanate (MDI, purity 99.5%, moisture content 0.02%), 5g of 1,4-butanediol, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI (solvent volume to monomer mass ratio 4ml:1g).

[0045] Preparation of liquid precursor: Polyoxyethylene glycol was vacuum dehydrated at 110°C and -0.097 MPa for 3 hours, cooled to 60°C, and then dissolved in the above electrolyte and stirred for 45 minutes until homogeneous; at the same time, MDI was melted at 60°C, 1,4-butanediol was added and stirred for 10 minutes, and then the mixture was added to the electrolyte and polyoxyethylene glycol mixture system, and stirred for another 20 minutes at 60°C. The whole process was carried out under a nitrogen atmosphere.

[0046] Battery Assembly: LiFePO4 / Li batteries were assembled in an argon-filled glove box (with water and oxygen content below 0.1 ppm). The positive electrode was prepared by coating an aluminum foil with a mixture of LiFePO4, acetylene black, and polyvinylidene fluoride in a mass ratio of 8:1:1; the negative electrode was a lithium metal sheet; during assembly, the separator was placed first, and 40 μl of precursor solution was dropped onto the separator before sealing the battery.

[0047] Curing and molding: The assembled battery is placed in a 60℃ oven for curing for 10 hours to obtain an in-situ polymerized polyurethane solid electrolyte battery.

[0048] Performance test results: Room temperature ionic conductivity is 4.1 × 10⁻⁶ -4S / cm; tensile strength 12MPa; elastic recovery rate 93%; first discharge capacity at 0.2C rate is 158mAh / g, and capacity retention rate is 92% after 800 cycles.

[0049] Example 2. Solid electrolyte for lithium metal batteries

[0050] Raw material preparation: Select 80g of polyoxyethylene glycol (number average molecular weight 6000), 15g of 4,4'-diphenylmethane diisocyanate (MDI, purity 99.5%, moisture content 0.02%), 5g of 1,4-butanediol, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI.

[0051] Preparation of liquid precursor: Same as in Example 1.

[0052] Battery Assembly: NCM811 / Li batteries were assembled in an argon-filled glove box. The positive electrode was prepared by coating aluminum foil with NCM811, acetylene black, and polyvinylidene fluoride in a mass ratio of 85:10:5; the negative electrode was a lithium metal sheet; the battery was sealed after adding 40 μl of precursor solution.

[0053] Curing and molding: Same as in Example 1.

[0054] Performance test results: Room temperature ionic conductivity is 2.8 × 10⁻⁶ -4 S / cm; tensile strength 10MPa; elastic recovery rate 91%; first-cycle discharge capacity at 0.2C rate is 201mAh / g, and capacity retention rate is 88% after 800 cycles.

[0055] Example 3. Solid electrolyte for lithium metal batteries

[0056] Raw material preparation: Select 80g of polyoxyethylene glycol (number average molecular weight 6000), 15g of hexamethylene diisocyanate (HDI, purity 99.2%, moisture content 0.03%), 5g of ethylenediamine, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI.

[0057] Preparation of liquid precursor: Polyoxyethylene glycol was vacuum dehydrated at 110℃ and -0.097MPa for 3 hours, cooled to 60℃ and then dissolved in electrolyte and stirred for 45 minutes; HDI was melted at 60℃, ethylenediamine was added and stirred for 10 minutes, and then added to the above mixture and stirred at 60℃ for 20 minutes, under nitrogen protection throughout the process.

[0058] Battery Assembly: The LiCoO2 / Li battery was assembled in an argon-filled glove box. The positive electrode was coated on aluminum foil with LiCoO2, acetylene black, and polyvinylidene fluoride in a mass ratio of 90:5:5; the negative electrode was a lithium metal sheet; after adding 40 μl of precursor solution, the battery was sealed.

[0059] Curing and molding: Same as in Example 1.

[0060] Performance test results: Room temperature ionic conductivity is 5.8 × 10⁻⁶ -4 S / cm; tensile strength 8MPa; elastic recovery rate 95%; first-cycle discharge capacity at 0.2C rate is 142mAh / g, and capacity retention rate is 90% after 800 cycles, effectively suppressing the growth of lithium dendrites.

[0061] Example 4. Solid electrolyte for lithium-ion batteries

[0062] Raw material preparation: Select 80g of polyoxypropylene-ethylene copolymer (number average molecular weight 6000, polyoxyethylene segment accounts for 80%), 15g of 4,4'-diphenylmethane diisocyanate (MDI), 5g of 1,4-butanediol, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI.

[0063] Preparation of liquid precursor: Polyoxypropylene-oxyethylene copolymer was dehydrated at 115℃ and vacuum degree -0.096MPa for 3.5 hours, cooled to 55℃ and dissolved in electrolyte and stirred for 60 minutes; after MDI was melted, 1,4-butanediol was added, and then the above system was added and stirred for 25 minutes under nitrogen protection.

[0064] Battery assembly: The LiFePO4 / graphite battery was assembled in an argon-filled glove box. The positive electrode was made of a mixture of LiFePO4, acetylene black, and polyvinylidene fluoride in an 8:1:1 ratio coated with aluminum foil; the negative electrode was a graphite electrode; after adding 35 μl of precursor solution, the box was sealed.

[0065] Curing and molding: Curing in a 60℃ oven for 12 hours.

[0066] Performance test results: Room temperature ionic conductivity is 3.5 × 10⁻⁶ -4 S / cm; tensile strength 9MPa; elastic recovery rate 94%; first-cycle discharge capacity at 0.2C rate is 152mAh / g, and capacity retention rate is 93% after 1000 cycles.

[0067] Example 5. Solid electrolyte for lithium-ion batteries

[0068] Raw material preparation: Select 80g of polyoxypropylene-ethylene copolymer (number average molecular weight 6000, polyoxyethylene segment accounts for 80%), 15g of hexamethylene diisocyanate (HDI), 5g of ethylenediamine, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI.

[0069] Preparation of liquid precursor: The copolymer was dehydrated at 115℃ and vacuum degree -0.096MPa for 3.5 hours, cooled to 55℃ and dissolved in electrolyte and stirred for 60 minutes; after HDI melted, ethylenediamine was added, and then the above system was added and stirred for 25 minutes under nitrogen protection.

[0070] Battery assembly: NCM811 / graphite batteries were assembled in an argon-filled glove box. The positive electrode was coated with aluminum foil by mixing NCM811, acetylene black, and polyvinylidene fluoride in a ratio of 85:10:5; the negative electrode was a graphite electrode; after adding 35 μl of precursor solution, the box was sealed.

[0071] Curing and molding: Curing in a 60℃ oven for 12 hours.

[0072] Performance test results: Room temperature ionic conductivity is 3.2 × 10⁻⁶ -4 S / cm; tensile strength 7MPa; elastic recovery rate 92%; first-cycle discharge capacity at 0.2C rate is 195mAh / g, and capacity retention rate is 89% after 1000 cycles.

[0073] Example 6. Solid electrolyte for lithium-ion batteries

[0074] Raw material preparation: Select 80g of polyoxyethylene glycol (number average molecular weight 6000), 15g of 4,4'-diphenylmethane diisocyanate (MDI), 5g of ethylenediamine, and 400ml of electrolyte composed of DOL / DME (volume ratio 5:5) and 1M LiTFSI.

[0075] Preparation of liquid precursor: Polyoxyethylene glycol was dehydrated at 120℃ and vacuum degree -0.098MPa for 2.5 hours, cooled to 60℃ and dissolved in electrolyte and stirred for 30 minutes; after MDI was melted, ethylenediamine was added, and then the above system was added and stirred for 15 minutes under nitrogen protection.

[0076] Battery assembly: NCM811 / silicon cells were assembled in an argon-filled glove box. The positive electrode was coated with aluminum foil by mixing NCM811, acetylene black, and polyvinylidene fluoride in a ratio of 85:10:5; the negative electrode was a silicon-based electrode; after adding 50 μl of precursor solution, the cells were sealed.

[0077] Curing and molding: Curing in a 60℃ oven for 8 hours.

[0078] Performance test results: Room temperature ionic conductivity is 4.8 × 10⁻⁶ -4S / cm; tensile strength 11MPa; elastic recovery rate 90%; first-cycle discharge capacity at 0.2C rate is 186mAh / g, and capacity retention rate is 85% after 500 cycles, effectively buffering the volume change of silicon anode.

[0079] Industrial Application Prospects

[0080] The polyurethane elastomer solid electrolyte of the present invention has broad industrial application prospects due to its excellent comprehensive performance.

[0081] In the field of power lithium batteries, it can be applied to electric vehicles, hybrid vehicles, etc. Electric vehicles have extremely high requirements for the safety, energy density, and cycle life of lithium batteries. This polyurethane elastomer solid electrolyte has no risk of leakage, good thermal stability, and can effectively avoid safety accidents caused by battery problems during electric vehicle operation. At the same time, its high ionic conductivity and good cycle stability can improve the driving range of electric vehicles and the lifespan of batteries, reducing user operating costs.

[0082] In the field of energy storage batteries, this technology is suitable for large-scale energy storage power stations. Energy storage power stations require batteries that can operate stably for a long time and withstand different ambient temperatures. This electrolyte exhibits stable performance over a wide temperature range and has a long cycle life, meeting the long-term usage requirements of energy storage power stations and providing strong support for the storage and utilization of renewable energy.

[0083] In the field of lithium-ion batteries for consumer electronics, these batteries can be used in portable electronic devices such as smartphones, laptops, and tablets. Consumer electronic devices have strict limitations on the size and weight of batteries. This thin electrolyte film (20-50μm) and lightweight design helps reduce the size and weight of the battery. At the same time, its high safety can prevent safety issues such as explosions caused by battery overheating in consumer electronic devices.

[0084] Furthermore, the preparation process of this invention is simple, the raw material cost is low, and it is easy to achieve large-scale industrial production. Currently, the relevant pilot production line has been initially built, and the performance indicators of the produced polyurethane elastomer solid electrolyte products have all met the design requirements. It is expected to achieve commercial application within the next 3-5 years, providing key material support for the development of the solid-state lithium battery industry and promoting the further upgrading of the new energy industry.

Claims

1. A solid electrolyte material for a lithium battery, characterized by being A polyurethane elastomer is composed of a polyether ion-conducting soft segment and an isocyanate cross-linking hard segment in a solvent, and has a chemical structural formula as follows: ； wherein: the soft segment is a polyether polyol with a number average molecular weight of 2000 or more, and accounts for 66-90% of the total mass of the polyurethane elastomer; the hard segment is formed by the reaction of a diisocyanate and a chain extender, and accounts for 10-34% of the total mass of the polyurethane elastomer; the solvent is an ether solvent, and the ratio of the solvent (volume) to the monomer (mass) is (1-6 ml):1 g.

2. The solid-state electrolyte material of claim 1, wherein, The polyether polyol in the soft segment is polyoxyethylene, and the number of repeating units of the polyoxyethylene is 20-100.

3. The solid-state electrolyte material of claim 1, wherein, The diisocyanate in the hard segment is selected from 4,4'-diphenylmethane diisocyanate (MDI) and hexamethylene diisocyanate (HDI).

4. The solid-state electrolyte material of claim 1, wherein, The ether solvent is selected from DOL, DME and 1MLiTFSI.

5. The method of producing a solid-state electrolyte material according to any one of claims 1 to 4, wherein The synthesis route is as follows: ； The specific steps of synthesis are as follows: (1) Preparation of polymerization raw materials: the polyether polyol is dehydrated at 100-120°C and a vacuum degree of-0.095 MPa to-0.099 MPa for 2-4 hours to remove the water in the polyether polyol, so that the water content after dehydration is less than 0.05%, thereby avoiding the reaction of water and diisocyanate to form urea bonds and affecting the quality of the prepolymer; then the temperature is cooled to 50-60°C; at the same time, diisocyanate with a purity of ≥99% and a water content of ≤0.03% is melted at 60-70°C; (2) Copolymerization reaction: the polyether polyol is dissolved in anhydrous ether electrolyte solvent, stirred and mixed at 40-80°C for 30-60 minutes until uniform, then the melted diisocyanate is added, and stirring is continued for 15-30 minutes until uniform, wherein the ratio of the hydroxyl group of the polyether polyol to the isocyanate group of the diisocyanate is 1:(1.5-4); (3) Curing and forming: the mixed solution is used as an electrolyte to assemble a battery, 30-50 microliters of the mixed solution is added dropwise on a separator, and then the battery is sealed and placed in a 60°C air oven for curing for 8-12 hours to obtain a polyurethane elastomer solid-state electrolyte polymerized in situ; during the curing process, the hydrogen bond reaction between the excess isocyanate and the hydroxyl group and the isocyanate group on the urethane group can cross-link the molecular chains to form a stable three-dimensional network structure.

6. A solid-state lithium battery, characterized by, The solid-state electrolyte material as claimed in any one of claims 1-4 is used as a lithium battery electrolyte material, and the thickness of the solid-state electrolyte layer is 20-50 μm.

7. The solid-state lithium battery of claim 6, wherein the solid-state lithium battery is a lithium metal battery. The lithium battery positive electrode is selected from LiFeP04, NCM811, LiCo02, LiNi 0.5 Mn 1.5 O4, and the negative electrode is selected from metal lithium and graphite.

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