Multilayer electrolyte membrane for solid-state batteries and method for producing the same

Abstract

The application discloses a kind of multilayer electrolyte membrane for solid-state battery and preparation method thereof, comprising: first layer film, the first layer film has oxidation resistance, for being contacted with high nickel positive electrode material;Second layer film, the second layer film includes porous lining, the porous lining is stored with sacrificial additive, the sacrificial additive can be released during battery cycle;Third layer film, the third layer film has reduction resistance, for being contacted with lithium metal negative electrode material.The application constructs the electrolyte membrane of multilayer structure, uses oxidation-resistant polymer to positive electrode, reduction-resistant polymer to negative electrode.Wide electrochemical window polymer solid electrolyte is constructed, can simultaneously match high nickel positive electrode and lithium metal negative electrode.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a multilayer electrolyte membrane for solid-state batteries and its preparation method. Background Technology

[0002] One of the key challenges facing lithium-ion batteries today is improving battery safety. Solid-state electrolytes, with their non-flammable and leak-proof properties, are crucial materials for effectively addressing safety concerns. Solid-state electrolytes can be categorized into two systems based on their materials: inorganic solid-state electrolytes and polymer solid-state electrolytes. Among these, polymer solid-state electrolytes have become ideal electrolyte materials for solid-state batteries due to their excellent contact interface, superior processability, and combination of flexibility and mechanical strength.

[0003] With the rapid development of the low-altitude economy, higher demands are being placed on the energy density of lithium batteries, in addition to safety. High-energy-density nickel-containing ternary cathodes (NCM) and lithium metal anodes have become ideal materials. NCM / Li solid-state batteries, however, place even higher demands on polymer solid-state electrolytes, requiring both oxidation and reduction resistance. While commonly used polyethylene oxide (PEO) and polymethyl methacrylate (PMMA) exhibit good reduction resistance, they are easily oxidized and decomposed under high voltages. Conversely, PVDF and polyacrylonitrile (PAN), which also possess oxidation resistance, are easily reduced upon contact with lithium metal. Therefore, constructing polymer solid-state electrolytes with a wide electrochemical window has become a core issue.

[0004] Researchers have proposed several solutions to this problem, such as constructing composite films with gradient structures and forming a CEI layer on the surface of cathode particles.

[0005] The patent application with application number 201810589634.3 describes a composite solid electrolyte membrane with a gradient distribution of inorganic electrolyte. A higher content of inorganic solid electrolyte on the positive electrode side allows it to withstand higher voltages, while a higher content of polymer electrolyte on the negative electrode side better suppresses lithium dendrites and alleviates negative electrode volume expansion. This gradient design balances the requirements for high voltage resistance and suppression of lithium dendrites and negative electrode volume expansion. However, increasing the inorganic material content is only effective in improving the polymer's oxidation resistance, as polymers that are not oxidation-resistant will still be oxidized by the positive electrode.

[0006] Patent application number 202211029889.7 describes a composite solid electrolyte membrane containing boron-containing additives and boron-containing lithium salts. During battery cycling, the boron-containing additives oxidize and decompose earlier than the polymer electrolyte, forming lithium borate (Li3BO3) on the surface of the cathode particles. This prevents direct contact between the layered oxide cathode and the polymer electrolyte, thus avoiding catalytic oxidation and solving the oxidation resistance problem of the polymer solid electrolyte membrane. However, the rupture of the CEI layer leads to the continuous consumption of the additives, eventually causing the cathode to re-enter contact with the polymer. Summary of the Invention

[0007] The purpose of this invention is to provide a multilayer electrolyte membrane for solid-state batteries and its preparation method. The main objective is to invent a multilayer electrolyte membrane for solid-state batteries, characterized by its stability against both high-nickel cathodes and lithium metal anodes, while also exhibiting ultra-long cycle stability.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0009] A multilayer electrolyte membrane for solid-state batteries, comprising, in sequence:

[0010] The first film has oxidation resistance and is used to contact the high-nickel cathode material;

[0011] The second membrane includes a porous liner that stores a sacrificial additive that can be released during battery cycling.

[0012] The third layer film, which has reduction resistance, is used to contact the lithium metal anode material.

[0013] The above technical solution can effectively improve battery performance and provide dual protection against oxidation and reduction: the first and third film layers have oxidation resistance and reduction resistance, respectively, which can effectively cope with the oxidation and reduction reactions of high-nickel cathode and lithium metal anode materials in battery cycling, ensuring long-term stable operation of the battery and extending its service life.

[0014] Optimize battery safety: During battery cycling, sacrificial additives are gradually released while the battery is in operation, mitigating the side effects caused by battery reactions and enhancing battery safety and stability, especially under high temperature or high load conditions.

[0015] Preferably, the first layer of the membrane comprises an oxidation-resistant polymer, a lithium salt, a sacrificial additive, and a plasticizer, and the third layer of the membrane comprises a reduction-resistant polymer, a lithium salt, a sacrificial additive, and a plasticizer.

[0016] Preferably, the sacrificial additive is one of lithium tetrafluoroborate (LiBF4) and lithium nitrate (LiNO3).

[0017] By using sacrificial additives, such as LiBF4 and LiNO3, controlled ion release can be provided during the battery's charge and discharge processes. This characteristic helps to effectively avoid risks caused by lithium dendrite growth or high-temperature reactions, further improving battery safety and cycle stability.

[0018] The first and third membranes contain sacrificial additives lithium tetrafluoroborate (LiBF4) and lithium nitrate (LiNO3), respectively. LiBF4 can form an inorganic CEI layer containing boron and phosphorus (B) on the surface of the cathode particles, while LiNO3 can form an SEI layer containing nitrogen (N) on the lithium metal surface, thereby improving cycle performance. The sacrificial additives stored in the second membrane can be added to the first and third membranes, ultimately achieving an ultra-long cycle stability system.

[0019] Preferably, the oxidation-resistant polymer is at least one selected from polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyacrylonitrile (PAN), polypropylene carbonate (PPC), and polyvinyl chloride (PVC); PVDF and PAN are preferred. The reduction-resistant polymer is at least one selected from polyethylene oxide (PEO), polymethyl methacrylate (PMMA), and polydimethylsiloxane (PDMS); PMMA and PEO are preferred.

[0020] The lithium salt is one of lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium difluorooxalate borate (LiDFOB), lithium bis(difluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI); wherein LiPF6, LiClO4, and LiDFOB are preferred.

[0021] The plasticizers are classified into solid plasticizers and functional plasticizers. The solid plasticizers are characterized by being solid at room temperature and comprising at least one of ethylene carbonate (EC), sulfolane (TMS), and succinate (SN). The functional plasticizers are one of propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), 1,2-dimethoxypropane (DMP), dimethoxymethane (DMM), ethylene glycol dimethyl ether (DME), acetonitrile (ACN), trimethyl phosphate (TMP), triethyl phosphate (TEP), fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl sulfate (DTD), and 1,3-propenesulfonate lactone (PST). VC, FEC, PC, and TMP are preferred.

[0022] Preferably, the porous liner is one of PE membrane, PP membrane, non-woven fabric, glass fiber membrane, or electrospun membrane, wherein the electrospun membrane is PAN or PVDF, and the thickness of the porous liner is 3μm-30μm, with a porosity of not less than 20%. Preferably, it is a non-woven fabric with a thickness of 5-15μm and a porosity of not less than 30%.

[0023] Preferably, the mass percentages of each component in the first layer of the film are as follows: 8% to 22.5% of the antioxidant polymer, 7.5% to 12% of the lithium salt, 0.5% to 5% of the sacrificial additive, and 70% to 80% of the plasticizer.

[0024] The mass percentages of the components in the third layer membrane are as follows: 8%–22.5% of the reduction-resistant polymer, 7.5%–12% of the lithium salt, 0.5%–5% of the sacrificial additive, and 70%–80% of the plasticizer.

[0025] By adopting the above technical solution, the multilayer membrane structure of the present invention can effectively improve the ionic conductivity of the solid electrolyte membrane. The polymer of the first membrane has good oxidation resistance and is matched with the high-nickel cathode. The polymer of the third membrane has good reduction resistance and can be matched with the lithium metal anode. In the application of high-nickel cathode materials and lithium metal anodes, it has better ion conduction performance, thereby improving the charging and discharging efficiency and capacity retention of the battery.

[0026] By precisely controlling the material and component ratios of each membrane layer, the electrolyte membrane possesses excellent mechanical strength and chemical stability, reducing membrane damage or performance degradation caused by stress changes or environmental factors during battery charging and discharging.

[0027] In this invention, the first membrane comprises an oxidation-resistant polymer, a lithium salt, a sacrificial additive (lithium tetrafluoroborate), and a plasticizer; the second membrane comprises a porous liner and a sacrificial additive; and the third membrane comprises a reduction-resistant polymer, a lithium salt, a sacrificial additive (lithium nitrate), and a plasticizer.

[0028] A method for preparing a multilayer electrolyte membrane for solid-state batteries, comprising the following steps:

[0029] S1. The first film is prepared by casting: the antioxidant polymer, lithium salt, sacrificial additive and plasticizer are added to the sealed mixing tank in the mass ratio, the temperature is controlled and the mixture is stirred evenly to obtain the first slurry. The first slurry is poured into the material box of the casting machine and cast into shape using the casting machine. After solidification, the first film is obtained.

[0030] In the first slurry, the polymer and lithium salt components account for 20%-30% of the total mass, preferably 24%-28%, and the polymer accounts for 40%-75% of the total mass of the polymer and lithium salt components, preferably 50%-60%. The plasticizer accounts for 70%-80% of the total mass, preferably 72%-76%, and the solid plasticizer accounts for 85%-100% of the total mass of the plasticizer, preferably 89%-94%.

[0031] S2. Preparation of the second film: Add the sacrificial additive and solvent to the mixing tank and stir evenly to obtain the second slurry. Use a casting machine to cast the second film on the porous liner.

[0032] The solvent is DME, ACN, acetone (AC), ethanol (ET), or N-methylpyrrolidone (NMP), with DME being preferred. The slurry is a white turbid liquid or a colorless transparent solution, with a solid content of 1%-30%, preferably 10%. The stirring speed is 100-2000 rpm, and the stirring time is 10-60 min. The stirring speed is preferably 100-300 rpm; the stirring time is preferably 30 min.

[0033] S3. Preparation of the third layer film by casting method: Add the reduction-resistant polymer, lithium salt, sacrificial additive and plasticizer into a sealed mixing tank according to the mass ratio, and stir evenly under controlled temperature to obtain the third slurry. Then use a casting machine to cast and form the third layer film.

[0034] S4. The first, second, and third membranes are stacked and then hot-rolled to obtain a multilayer electrolyte membrane.

[0035] The preparation method provided by this invention combines casting and hot rolling techniques, which not only simplifies the membrane preparation process and reduces production costs, but also ensures uniform thickness and excellent film quality for each layer, thereby improving the overall performance of the electrolyte membrane. This method has good operability and industrial feasibility, can adapt to production needs of different scales, and has broad commercial application prospects.

[0036] Preferably, the stirring temperature in steps S1 and S3 is controlled at 100℃-180℃.

[0037] The stirring tank is characterized by being sealable, heatable, and capable of stirring. The stirring speed is 100-2000 rpm, the stirring temperature is 100℃-180℃, and the stirring time is 30-180 min. The preferred stirring speed is 900-1000 rpm, the preferred stirring temperature is 110-140℃, and the preferred stirring time is 120 min.

[0038] Preferably, in steps S1 and S3, the temperature of the casting machine hopper needs to be consistent with the stirring temperature. The casting process controls the doctor blade gap to be between 3μm and 400μm, and the belt speed to be between 0.05m / min and 1m / min, preferably 0.5m / min. After casting, the slurry is cooled to solidify into a film. The cooling method can be natural cooling or semiconductor cooling. The semiconductor cooling setting temperature is -10℃ to 10℃. The cooling method and cooling temperature are matched with the belt speed to ensure that the slurry solidifies into a film before winding. In step S2, the casting process controls the doctor blade gap to be between 0 and 50μm, preferably 5μm, and the belt speed to be between 0.05m / min and 2m / min, preferably 1m / min. The drying temperature is 60-100℃, preferably 80℃. After drying, a second film is obtained.

[0039] Preferably, during the hot rolling process, the first and third film layers soften and, under pressure, penetrate into the gaps of the second film layer and bond tightly. The hot rolling speed is 0.05 m / min to 1 m / min, preferably 0.54 m / min. The softening of the polymer film is achieved by controlling the roller temperature, which is 60℃ to 140℃, preferably 100℃, and the reduction rate is 10% to 90%.

[0040] Compared with the prior art, the advantages of the present invention are as follows:

[0041] 1. This invention constructs a multilayer electrolyte membrane, using an oxidation-resistant polymer for the positive electrode and a reduction-resistant polymer for the negative electrode. A polymer solid electrolyte with a wide electrochemical window is constructed, capable of simultaneously matching a high-nickel positive electrode and a lithium metal negative electrode; the second layer is a porous liner with excellent mechanical strength, improving the mechanical strength of the composite membrane while storing sacrificial additives.

[0042] 2. This invention uses sacrificial additives to form CEI and SEI layers on the surface of positive electrode particles and lithium metal negative electrode to improve cycle stability. At the same time, additional sacrificial additives are stored in the second layer film and supplemented by diffusion to the first and third layers film to achieve ultra-long cycle life.

[0043] 3. In this invention, the combination of multi-layer structures is completed in one step by hot pressing. The process steps are simple and efficient. At the same time, heat treatment improves the interface between multi-layer structures and reduces internal resistance. Attached Figure Description

[0044] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a flowchart illustrating the preparation process of the multilayer electrolyte membrane for solid-state batteries in this invention.

[0046] Figure 2 This is a schematic diagram of the multilayer electrolyte membrane structure for solid-state batteries in this invention.

[0047] Figure 3 The cycling performance (0.2 / 0.5C) of the NCM811 / Li soft pack multilayer electrolyte membrane composition in this invention is shown. Detailed Implementation

[0048] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] Example 1

[0050] A method for preparing a multilayer electrolyte membrane for solid-state batteries includes the following steps:

[0051] The first film was prepared by casting: PVDF, LiPF6, LiBF4, TMS, and VC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 min at a speed of 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the first film.

[0052] Preparation of the second membrane: LiBF4, LiNO3, and DME were added to a mixing tank at a mass ratio of 5%:5%:90%, stirred at 250 rpm for 30 min at room temperature, and a 12 μm nonwoven fabric was used as a substrate. The slurry was cast into a film using a casting machine with a doctor blade gap of 5 μm and a belt speed of 1 m / min. The second membrane was obtained by hot air drying at 80℃.

[0053] The third layer of film was prepared by casting: PEO, LiPF6, LiNO3, TMS, and FEC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%, heated and stirred at 110℃ for 120 min at 900 rpm. The slurry was then poured into a material box at 110℃ and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the third layer of film.

[0054] The first layer membrane A, the second layer membrane B, and the third layer membrane C were stacked and then subjected to hot rolling at a rolling speed of 0.5 m / min, a rolling temperature of 100℃, and a reduction rate of 60%, to obtain a multilayer electrolyte membrane, which was designated as sample 1.

[0055] Comparative Example 1

[0056] The preparation of an electrolyte membrane includes the following steps:

[0057] A-film: PVDF, LiPF6, LiBF4, TMS, and VC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain A-film.

[0058] B membrane: 12μm nonwoven fabric is selected as the lining.

[0059] C-film: PEO, LiPF6, LiNO3, TMS, and FEC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the C-film.

[0060] After stacking membranes A, B, and C, they were subjected to hot rolling at a rolling speed of 0.5 m / min and a rolling temperature of 100℃, with a reduction rate of 60%, to obtain a multilayer electrolyte membrane, which was designated as sample 2.

[0061] Comparative Example 2

[0062] The preparation of an electrolyte membrane includes the following steps:

[0063] A-film: PVDF, LiPF6, LiBF4, TMS, and VC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain A-film.

[0064] B membrane: 12μm nonwoven fabric is selected as the lining.

[0065] C-film: PVDF, LiPF6, LiNO3, TMS, and FEC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the C-film.

[0066] After stacking membranes A, B, and C, they were subjected to hot rolling at a rolling speed of 0.5 m / min and a rolling temperature of 100℃, with a reduction rate of 60%, to obtain a multilayer electrolyte membrane, which was designated as sample 3.

[0067] Comparative Example 3

[0068] A film: PEO, LiPF6, LiBF4, TMS, and VC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the A film.

[0069] B membrane: 12μm nonwoven fabric is selected as the lining.

[0070] C-film: PEO, LiPF6, LiNO3, TMS, and FEC were added to a sealed mixing tank in a mass ratio of 14%:10%:4%:67%:5%. The mixture was heated and stirred at 110°C for 120 minutes at 900 rpm. The slurry was then poured into a material box at 110°C and cast into a film using a casting machine with a doctor blade gap of 120 μm, a belt speed of 0.5 m / min, and natural cooling to obtain the C-film.

[0071] After stacking membranes A, B, and C, they were subjected to hot rolling at a rolling speed of 0.5 m / min and a rolling temperature of 100℃, with a reduction rate of 60%, to obtain a multilayer electrolyte membrane, which was designated as sample 4.

[0072] Samples 1-4 were assembled into NCM811 / Li coin cells and their 0.33 / 0.33C cycle performance was tested, with the A film / first layer facing NCM811 and the C film / third layer facing Li.

[0073] Table 1 shows the number of coin cell cycles (0.33 / 0.33C) of NCM811 / Li for samples 1-4.

[0074] sample Cyc number of cycles Capacity retention rate % Sample 1 200 98.2 Sample 2 200 87.6 Sample 3 200 80.1 Sample 4 50 ＜80

[0075] As shown in the table above, this invention optimizes the functionality of each membrane layer, providing targeted protection for different battery materials (positive and negative electrodes). Specifically, when the first and third membrane layers come into contact with the positive and negative electrode materials respectively, their oxidation and reduction resistance effectively prevent membrane damage and performance degradation, thereby extending battery life. Furthermore, the second membrane layer (layer B) employs sacrificial additives (such as LiBF4 and LiNO3) and stores them through a porous liner. These additives are gradually released during battery charging and discharging, reducing unnecessary reactions within the battery, particularly effectively inhibiting the growth of lithium dendrites. The formation of these dendrites can lead to short circuits, failures, or overheating, causing safety issues. The controlled release of the sacrificial additives further enhances battery safety under extreme conditions such as high-rate charging and discharging, and overcharging / over-discharging.

[0076] In the comparative samples, whether it's sample 2, sample 3, or sample 4, the electrolyte membrane has a single structure. While membranes A, B, and C are present, they lack the sacrificial additive release mechanism found in Example 1. The lack of a second layer for storing the sacrificial additive prevents its active release during battery charging and discharging. This makes it difficult to effectively control lithium dendrite growth and side reactions during battery use, especially at high temperatures or high charge / discharge rates, leading to gradual performance degradation and significant safety hazards.

[0077] The NCM811 electrode was bonded to the first layer of the membrane in Sample 1, and then hot-rolled at a rolling speed of 0.5 m / min and a rolling temperature of 100℃, with a reduction rate of 60%, to obtain an integrated positive electrode-multilayer electrolyte membrane structure. The third layer of the membrane was then assembled with Li to form a 3 Ah NCM811 / Li pouch, and its 0.2 / 0.5C cycle performance was tested.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multilayer electrolyte film for solid-state batteries, characterized by, Comprise in sequence: The first layer film has oxidation resistance for contacting with high nickel positive electrode material; the first layer film comprises oxidation resistant polymer, lithium salt, sacrificial additive lithium tetrafluoroborate LiBF4 and plasticizer; The second layer film comprises porous lining body, which stores sacrificial additive lithium tetrafluoroborate LiBF4 and lithium nitrate LiNO3, which can be released during battery cycle; The third layer film has reduction resistance for contacting with lithium metal negative electrode material, and comprises reduction resistant polymer, lithium salt, sacrificial additive lithium nitrate LiNO3 and plasticizer.

2. The multilayer electrolyte membrane for a solid-state battery according to claim 1, characterized by The oxidation resistant polymer is at least one of polyvinylidene fluoride PVDF, polyvinylidene fluoride-hexafluoropropylene PVDF-HFP, polyacrylonitrile PAN, polypropylene carbonate PPC and polyvinyl chloride PVC; the reduction resistant polymer is at least one of polyethylene oxide PEO, polymethyl methacrylate PMMA and polydimethylsiloxane PDMS; The lithium salt is one of lithium perchlorate LiClO4, lithium hexafluoroarsenate LiAsF6, lithium hexafluorophosphate LiPF6, lithium difluoro oxalate borate LiDFOB, lithium bisdifluorosulfonimide LiFSI and lithium bis-trifluoromethylsulfonylimide LiTFSI; The plasticizer is divided into solid plasticizer and functional plasticizer, the solid plasticizer is at least one of ethylene carbonate EC, tetramethylene sulfone TMS and succinonitrile SN; the functional plasticizer is one of propylene carbonate PC, dimethyl carbonate DMC, diethyl carbonate DEC, ethyl methyl carbonate EMC, 1,2-dimethoxypropane DMP, dimethoxymethane DMM, ethylene glycol dimethyl ether DME, acetonitrile ACN, trimethyl phosphate TMP, triethyl phosphate TEP, fluoroethylene carbonate FEC, vinylene carbonate VC and vinyl sulfate DTD, 1,3-propylene sulfone acid lactone PST.

3. The multilayer electrolyte membrane for a solid-state battery according to claim 1, characterized by The porous lining body is one of PE separator, PP separator, non-woven fabric, glass fiber membrane and electrospun membrane, wherein the electrospun membrane is PAN or PVDF, the thickness of the porous lining body is 3-30 μm, and the porosity is not less than 20%.

4. The multilayer electrolyte membrane for a solid-state battery according to claim 1, characterized by The mass ratio of each component in the first layer film is that the mass ratio of oxidation resistant polymer is 8%-22.5%, the mass ratio of lithium salt is 7.5%-12%, the mass ratio of sacrificial additive is 0.5%-5%, and the mass ratio of plasticizer is 70%-80%; The mass ratio of each component in the third layer film is that the mass ratio of reduction resistant polymer is 8%-22.5%, the mass ratio of lithium salt is 7.5%-12%, the mass ratio of sacrificial additive is 0.5%-5%, and the mass ratio of plasticizer is 70%-80%.

5. A method for producing a multilayer electrolyte film for a solid-state battery, characterized by The method for preparing the multilayer electrolyte film of any one of claims 1-4 comprises the following steps: S1, preparing the first layer film: adding oxidation resistant polymer, lithium salt, sacrificial additive and plasticizer into a sealed stirring tank according to the mass ratio, uniformly stirring under temperature control to obtain a first slurry, and then using a casting machine to form the first layer film; S2, preparing the second layer film: adding the sacrificial additive and the solvent into the stirring tank to stir uniformly to obtain a second slurry, and using a casting machine to cast and form the second layer film on a porous liner; S3, preparing the third layer film: adding the reduction-resistant polymer, the lithium salt, the sacrificial additive and the plasticizer into a sealed stirring tank according to the mass ratio, stirring uniformly under temperature control to obtain a third slurry, and then using a casting machine to cast and form the third layer film; S4, stacking the first layer film, the second layer film and the third layer film and then performing hot rolling to obtain a multilayer electrolyte film.

6. The method of claim 5, wherein the method is characterized by: The stirring temperature in steps S1 and S3 is controlled at 100-180°C.

7. The method of claim 5, wherein the method is characterized by: The temperature of the casting machine hopper in steps S1 and S3 needs to be consistent with the stirring temperature, the casting forming is controlled at a doctor blade gap of 3-400μm, the belt speed is 0.05-1m / min, and after casting, cooling is performed to solidify the slurry into a film, and the cooling method is natural cooling or semiconductor cooling, the semiconductor cooling is set at a temperature of-10-10°C to ensure that the slurry is solidified into a film before winding; the casting forming in step S2 is controlled at a doctor blade gap of 0-50μm, and the belt speed is 0.05-2m / min.

8. The method of claim 5, wherein the method is characterized by: During the hot rolling process, the first layer film and the third layer film soften, penetrate into the gap of the second layer film under the action of pressure and are tightly combined, the hot rolling speed is 0.05-1m / min, the polymer film softening is achieved by controlling the roller temperature, the roller temperature is 60-140°C, and the reduction rate is 10-90%.

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