Double-layer solid electrolyte membrane and preparation method therefor

Abstract

Provided are a double-layer solid electrolyte membrane and a preparation method therefor. The double-layer solid electrolyte membrane comprises a positive-electrode-side solid electrolyte layer and a negative-electrode-side solid electrolyte layer, wherein the positive-electrode-side solid electrolyte layer comprises a positive-electrode-side polymer matrix, a lithium salt and a first conductive ceramic powder, the content of the first conductive ceramic powder being 5-20 mass% relative to the total mass of the positive-electrode-side solid electrolyte layer; and the negative-electrode-side solid electrolyte layer comprises a negative-electrode-side polymer matrix, optional butanedinitrile, an optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder being a lithium-lanthanum-zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder being 80-99 mass% relative to the total mass of the negative-electrode-side solid electrolyte layer. The double-layer solid electrolyte membrane has the same advantages of a high ionic conductivity and a high shear modulus as inorganic conductive ceramics, and the same advantage of good processability as an organic polymer.

Description

Double-layer solid electrolyte membrane and preparation method thereof Technical Field

[0001] The present invention relates to a double-layer solid electrolyte membrane and a preparation method thereof, as well as a solid-state lithium metal battery comprising the double-layer solid electrolyte membrane. Background Art

[0002] Lithium metal solid-state batteries are considered the most promising next-generation energy storage devices due to their high safety and high specific capacity. Traditional liquid electrolytes continuously react with lithium metal, resulting in the continuous consumption of lithium metal and the formation of inactive lithium, which leads to a continuous decline in battery life. Alternatively, uneven deposition of lithium dendrites can pierce the separator, causing the entire battery to fail and posing significant safety risks.

[0003] Solid electrolytes have high mechanical strength and are believed to be able to inhibit the growth of lithium dendrites. Among them, organic-inorganic composite solid electrolytes have good processing properties and are a hot topic of academic and industrial research. However, organic-inorganic composite electrolytes containing a low content of inorganic conductive ceramics (<70% by mass) do not have a high shear modulus and are not sufficient to effectively inhibit the growth of lithium dendrites. However, when the content of ceramic particles is further increased (for example, >80% by mass), due to the decrease in polymer content and limited bonding strength, the composite electrolyte membrane with a high ceramic particle content will become hard and brittle, and cannot be formed independently, which also limits its large-scale production.

[0004] In addition, the electrochemical window of the single polymer organic-inorganic composite electrolyte membrane is narrow, which cannot meet the requirements of simultaneous compatibility with lithium metal and high-voltage positive electrodes, limiting its ability to match higher voltage positive electrodes and affecting the realization of high-energy-density lithium metal all-solid-state batteries.

[0005] Summary of the Invention

[0006] The technical problem to be solved by the present invention is that in the current organic-inorganic composite solid electrolyte membrane, a high content of inorganic ceramics and polymers cannot be independently formed into a large-area membrane when composited.

[0007] To address the above technical issues, the present invention provides a novel solid electrolyte membrane employing a dual-layer solid electrolyte design, comprising a positive-side solid electrolyte layer with a high polymer content and a negative-side solid electrolyte layer with a high inorganic conductive ceramic content (80% by mass or greater, preferably >90% by mass). This membrane can be fabricated into a self-supporting organic-inorganic composite electrolyte membrane. The organic-inorganic composite electrolyte membrane of the present invention combines the advantages of high ionic conductivity and shear modulus of inorganic conductive ceramics with the excellent processing properties of organic polymers.

[0008] According to a first aspect of the present invention, a double-layer solid electrolyte membrane is provided, comprising a positive electrode side solid electrolyte layer and a negative electrode side solid electrolyte layer, wherein the positive electrode side solid electrolyte layer comprises a positive electrode side polymer matrix, a lithium salt and a first conductive ceramic powder, and the content of the first conductive ceramic powder is 5% to 20% by mass relative to the total mass of the positive electrode side solid electrolyte layer, and wherein the negative electrode side solid electrolyte layer comprises a negative electrode side polymer matrix, optional succinonitrile (SN), optional lithium salt and a second conductive ceramic powder, and the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80% to 99% by mass relative to the total mass of the negative electrode side solid electrolyte layer.

[0009] In some specific embodiments, the positive electrode side polymer matrix is ​​selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and polypropylene carbonate, preferably polyvinylidene fluoride-hexafluoropropylene copolymer.

[0010] In some specific embodiments, the negative electrode side polymer matrix is ​​one or more selected from polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide.

[0011] In some specific embodiments, the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6), preferably lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0012] In some specific embodiments, the first conductive ceramic powder is selected from one or more of lithium lanthanum titanium oxide (LLTO) powder, lithium lanthanum zirconium oxide (LLZO) powder, lithium lanthanum zirconium tantalum oxide (LLZTO) powder, and lithium aluminum titanium phosphate (LATP) powder LATP, preferably lithium lanthanum zirconium oxide (LLZO) powder.

[0013] In some specific embodiments, relative to the total mass of the positive electrode side solid electrolyte layer, the content of the positive electrode side polymer matrix is ​​60 mass% to 85 mass%, and / or the content of the lithium salt is 10 mass% to 35 mass%, and / or the content of the first conductive ceramic powder is 5 mass% to 20 mass%.

[0014] In some specific embodiments, relative to the total mass of the negative electrode side solid electrolyte layer, the content of the negative electrode side polymer matrix is ​​1 mass % to 20 mass %, and / or the content of succinonitrile is 0 mass % to 5 mass %, and / or the content of the lithium salt is 0 mass % to 10 mass %, and / or the content of the second conductive ceramic powder is 80 mass % to 99 mass %.

[0015] In some specific embodiments, the positive electrode side solid electrolyte layer and the negative electrode side solid electrolyte layer may each independently contain a plasticizer. The plasticizer is selected from one or more of polyethylene glycol, ethylene carbonate, butyl benzyl phthalate, and propylene carbonate.

[0016] In some specific embodiments, the particle size of the first conductive ceramic powder is 20 to 1000 nm, preferably 300 nm.

[0017] In some specific embodiments, the particle size of the second conductive ceramic powder is 20 to 1000 nm, preferably 300 nm.

[0018] In some specific embodiments, the thickness of the positive electrode side solid electrolyte layer is 5 μm-20 μm, and the thickness of the negative electrode side solid electrolyte layer is 5 μm-20 μm.

[0019] A second aspect of the present invention provides a method for preparing a double-layer solid electrolyte membrane, the method comprising the following steps:

[0020] (1) preparing a positive electrode side solid electrolyte slurry, applying the prepared positive electrode side solid electrolyte slurry on a release film and drying it to form a positive electrode side solid electrolyte layer;

[0021] (2) preparing a negative electrode side solid electrolyte slurry, applying the prepared negative electrode side solid electrolyte slurry on the positive electrode side solid electrolyte layer by scraping and drying to form a negative electrode side solid electrolyte layer and then forming a double-layer solid electrolyte membrane;

[0022] (3) peeling the double-layer solid electrolyte membrane from the release film and performing a pressure treatment,

[0023] The positive electrode side solid electrolyte slurry comprises a positive electrode side polymer matrix, a lithium salt and a first conductive ceramic powder, and the content of the first conductive ceramic powder is 5% to 20% by mass relative to the total dry basis mass of the positive electrode side solid electrolyte slurry, and

[0024] In which, the negative electrode side solid electrolyte slurry contains a negative electrode side polymer matrix, optional succinonitrile, optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80% to 99% by mass relative to the total dry basis mass of the negative electrode side solid electrolyte slurry.

[0025] In some specific embodiments, the positive electrode side polymer matrix is ​​one or more selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and polypropylene carbonate, preferably polyvinylidene fluoride-hexafluoropropylene copolymer.

[0026] In some specific embodiments, the negative electrode side polymer matrix is ​​one or more selected from polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide.

[0027] In some specific embodiments, the lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6), preferably lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0028] In some specific embodiments, the first conductive ceramic powder is selected from one or more of lithium lanthanum titanium oxide (LLTO) powder, lithium lanthanum zirconium oxide (LLZO) powder, lithium lanthanum zirconium tantalum oxide (LLZTO) powder, and lithium aluminum titanium phosphide (LATP) powder, preferably lithium lanthanum zirconium oxide (LLZO) powder.

[0029] In some specific embodiments, relative to the total dry mass of the positive electrode side solid electrolyte slurry, the content of the positive electrode side polymer matrix is ​​60 mass% to 85 mass%, and / or the content of the lithium salt is 10 mass% to 35 mass%, and / or the content of the first conductive ceramic powder is 5 mass% to 20 mass%.

[0030] In some specific embodiments, relative to the total dry mass of the negative electrode side solid electrolyte slurry, the content of the negative electrode side polymer matrix is ​​1 mass% to 20 mass%, and / or the content of the succinonitrile is 0 mass% to 5 mass%, and / or the content of the lithium salt is 0 mass% to 10 mass%, and / or the content of the second conductive ceramic powder is 80 mass% to 99 mass%.

[0031] In some specific embodiments, the viscosity of the positive electrode side solid electrolyte slurry and the negative electrode side solid electrolyte slurry is independently 180-250 mPa·s.

[0032] In some specific embodiments, the scraping thickness of the positive electrode side solid electrolyte slurry is 30-100 μm, and the thickness of the positive electrode side solid electrolyte layer after drying is 5 μm-20 μm, and the scraping thickness of the negative electrode side solid electrolyte slurry is 30-100 μm, and the thickness of the negative electrode side solid electrolyte layer after drying is 5 μm-20 μm.

[0033] The third aspect of the present invention provides the use of the double-layer solid electrolyte membrane of the first aspect of the present invention or the double-layer solid electrolyte membrane obtained by the preparation method of the second aspect of the present invention in a solid-state lithium metal battery.

[0034] A fourth aspect of the present invention provides a solid-state lithium metal battery, comprising the double-layer solid electrolyte membrane of the first aspect of the present invention or the double-layer solid electrolyte membrane prepared by the preparation method of the second aspect of the present invention. Preferably, the solid-state lithium metal battery is a semi-solid-state battery.

[0035] In summary, the present invention provides an organic-inorganic composite solid electrolyte membrane, which adopts a double-layer solid electrolyte design. In the polymer organic-inorganic composite electrolyte layer, the first layer is a high-pressure polymer organic-inorganic composite electrolyte layer with a low content of ceramic powder on the positive electrode side, and the second layer is a high-content ceramic powder on the negative electrode side (80% by mass or more, preferably >90% by mass). The first layer of high-voltage polymer can match the high-voltage positive electrode and has a very good film-forming effect. The second layer of electrolyte uses the first layer (positive electrode side) electrolyte membrane as a base, and is coated with an organic-inorganic composite electrolyte with a high content of conductive ceramic powder (solid electrolyte on the negative electrode side). The organic-inorganic composite electrolyte of the present invention has a relatively high shear modulus and can effectively inhibit the growth of lithium dendrites.

[0036] According to the double-layer structure solid electrolyte membrane design of the present invention, the high-content LLZO solid electrolyte on the negative electrode side can be tightly attached to the positive electrode side solid electrolyte. This double-layer electrolyte design ensures that the high-LLZO ceramic content of the negative electrode side solid electrolyte can be attached to the positive electrode side solid electrolyte with a low content of LLZO ceramic to form an independent film. Therefore, this double-layer structure design can not only produce solid electrolyte membranes on a large scale through roll-to-roll, but also the electrolyte membrane has higher oxidation resistance, can match high-voltage positive electrode materials, and realize solid-state batteries with higher energy density. At the same time, the double-layer structure solid electrolyte membrane according to this embodiment can be bent and folded, and has excellent flexibility. In addition, the electrochemical window of the double-layer structure solid electrolyte membrane according to the present invention is wider than that of the single-layer solid electrolyte membrane. On the basis of the above, the present invention also provides a method for preparing an organic-inorganic composite solid electrolyte membrane, which uses a traditional scraping film forming process without adding additional equipment, has low cost, simple method, controllable thickness, is suitable for large-scale production, and can also achieve the above technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic structural diagram of an embodiment of a double-layer solid electrolyte membrane according to the present invention.

[0038] FIG. 2 shows an optical photograph of a double-layer solid electrolyte membrane according to an embodiment of the present invention.

[0039] FIG. 3 shows an optical photograph of a single-layer solid electrolyte membrane according to a comparative example of the present invention.

[0040] FIG4 shows the test results of the electrochemical windows of the double-layer solid electrolyte membrane according to the embodiment of the present invention and the single-layer solid electrolyte membrane according to the comparative example. DETAILED DESCRIPTION

[0041] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, the terms used herein have the same meanings as those generally understood by those of ordinary skill in the art. The numerical limits or ranges set forth herein include endpoints, specifically all values ​​and subranges within the numerical limits or ranges.

[0042] The first aspect of the present invention provides a composite solid electrolyte membrane, as shown in FIG1 , the double-layer solid electrolyte membrane comprises a positive electrode side solid electrolyte layer 1 and a negative electrode side solid electrolyte layer 2,

[0043] The positive electrode side solid electrolyte layer 1 comprises a positive electrode side polymer matrix, a lithium salt and a first conductive ceramic powder, wherein the content of the first conductive ceramic powder is 5% to 20% by mass relative to the total mass of the positive electrode side solid electrolyte layer 1, and

[0044] Among them, the negative electrode side solid electrolyte layer 2 contains a negative electrode side polymer matrix, optional succinonitrile, optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80% to 99% by mass relative to the total mass of the negative electrode side solid electrolyte layer 2.

[0045] In the present invention, the term "optionally" means that the component is selectively included or not included in the composition, that is, depending on the specific embodiment, the content of the component may be 0 or may not be 0. Specifically, in the negative electrode side solid electrolyte layer 2 of the present invention, the content of succinonitrile and / or lithium salt may be 0. When the content of succinonitrile and lithium salt is both 0, the negative electrode side solid electrolyte layer 2 of the present invention comprises a negative electrode side polymer matrix and a second conductive ceramic powder.

[0046] In the present invention, the positive electrode side polymer matrix includes but is not limited to one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and polypropylene carbonate, preferably polyvinylidene fluoride-hexafluoropropylene copolymer. Relative to the total mass of the positive electrode side solid electrolyte layer 1, the content of the positive electrode side polymer matrix is ​​60% to 85% by mass, preferably 60% to 80% by mass. The weight average molecular weight of the positive electrode side polymer matrix (for example, polyvinylidene fluoride-hexafluoropropylene copolymer) is 100K-500K, such as 100K, 200K, 300K, 400K, 500K, etc., preferably 400K.

[0047] In the present invention, the negative electrode side polymer matrix includes but is not limited to one or more of polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide. Relative to the total mass of the negative electrode side solid electrolyte layer 2, the content of the negative electrode side polymer matrix is ​​1% by mass to 20% by mass, preferably 1% by mass to 8% by mass. The viscosity-average molecular weight of the negative electrode side polymer matrix (e.g., polyethylene oxide PEO) can be 600K-10000K, such as 600K, 2000K, 4000K, 5000K, 7900K, 10000K, etc., preferably 7900K.

[0048] In the present invention, the lithium salt can be selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6), preferably bis(trifluoromethanesulfonyl)imide (LiTFSI). The content of the lithium salt is 10% to 40% by mass, preferably 15% to 25% by mass, relative to the total mass of the positive electrode side solid electrolyte layer 1. The content of the lithium salt is 0% to 10% by mass, preferably 0% to 8% by mass, and more preferably 2% to 8% by mass, relative to the total mass of the negative electrode side solid electrolyte layer 2.

[0049] In the present invention, the first conductive ceramic powder can be selected from one or more of lithium lanthanum titanate (LLTO) powder, lithium lanthanum zirconate (LLZO) powder, lithium lanthanum zirconate tantalum (LLZTO) powder, and lithium aluminum titanium phosphate (LATP) powder, preferably lithium lanthanum zirconate (LLZO) powder. The content of the first conductive ceramic powder relative to the total mass of the positive-electrode solid electrolyte layer 1 is 5% to 20% by mass, for example, 5%, 10%, 15%, or 20% by mass, and preferably 10% to 15% by mass.

[0050] In the present invention, the content of the second conductive ceramic powder relative to the total mass of the negative electrode side solid electrolyte layer 2 is 80 mass% to 99 mass%, for example, it can be 80 mass%, 81 mass%, 82 mass%, 83 mass%, 84 mass%, 85 mass%, 86 mass%, 87 mass%, 88 mass%, 89 mass%, 90 mass%, 91 mass%, 92 mass%, 93 mass%, 94 mass%, 95 mass%, 96 mass%, 97 mass%, 98 mass%, 99 mass%, etc., preferably 85 mass% to 99 mass%, more preferably 89 mass% to 99 mass%.

[0051] For organic-inorganic composite electrolyte membranes, when the mass ratio of organic ceramic powder reaches 80% by mass or more, it can be considered that a polymer-in-ceramic structure is formed, in which lithium ions will be conducted along the continuous ceramic powder, giving the electrolyte membrane higher ionic conductivity and shear modulus.

[0052] In the present invention, the content of succinonitrile is 0% by mass to 5% by mass, preferably 2% by mass to 5% by mass, relative to the total mass of the negative electrode-side solid electrolyte layer.

[0053] In the present invention, the positive electrode side solid electrolyte layer and the negative electrode side solid electrolyte layer may each independently contain a plasticizer. The plasticizer may be selected from one or more of polyethylene glycol, ethylene carbonate, butyl benzyl phthalate, and propylene carbonate (PC). The content of the plasticizer relative to the total mass of the positive electrode side solid electrolyte layer or the negative electrode side solid electrolyte layer may be, for example, 1% to 20% by mass, preferably 5% to 10% by mass.

[0054] In the present invention, the particle size of the first conductive ceramic powder is 20 to 1000 nm, preferably 300 nm.

[0055] In the present invention, the particle size of the second conductive ceramic powder is 20 to 1000 nm, preferably 300 nm.

[0056] In the present invention, the thickness of the positive electrode side solid electrolyte layer is 5 to 20 μm, and the thickness of the negative electrode side solid electrolyte layer is 5 to 20 μm.

[0057] A second aspect of the present invention provides a method for preparing a double-layer solid electrolyte membrane, the method comprising the following steps:

[0058] (1) preparing a positive electrode side solid electrolyte slurry, applying the prepared positive electrode side solid electrolyte slurry on a release film and drying it to form a positive electrode side solid electrolyte layer;

[0059] (2) preparing a negative electrode side solid electrolyte slurry, applying the prepared negative electrode side solid electrolyte slurry on the positive electrode side solid electrolyte layer by scraping and drying to form a negative electrode side solid electrolyte layer and then forming a double-layer solid electrolyte membrane;

[0060] (3) The double-layer solid electrolyte membrane is peeled off from the release film and subjected to pressure treatment.

[0061] The positive electrode side solid electrolyte slurry may include a positive electrode side polymer matrix, a lithium salt and a first conductive ceramic powder, and the content of the first conductive ceramic powder is 5% to 20% by mass relative to the total dry mass of the positive electrode side solid electrolyte slurry (i.e., the mass of the slurry without solvent, the same below), and

[0062] Among them, the solid electrolyte slurry on the negative electrode side may include a negative electrode side polymer matrix, optional succinonitrile, optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80% to 99% by mass relative to the total dry basis mass of the solid electrolyte slurry on the negative electrode side.

[0063] In the present invention, relative to the total dry mass of the solid electrolyte slurry on the positive electrode side, the content of the polymer matrix on the positive electrode side can be 60 mass% to 85 mass%, and / or, the content of the lithium salt is 10 mass% to 35 mass%, and / or, the content of the first conductive ceramic powder is 5 mass% to 20 mass%.

[0064] In the present invention, relative to the total dry mass of the solid electrolyte slurry on the negative electrode side, the content of the negative electrode side polymer matrix can be 1 mass % to 20 mass %, and / or, the content of succinonitrile is 0 mass % to 5 mass %, and / or, the content of lithium salt is 0 mass % to 10 mass %, and / or, the content of the second conductive ceramic powder is 80 mass % to 99 mass %.

[0065] For example, in step (1), the first layer of the positive electrode side solid electrolyte is prepared by mixing the positive electrode side polymer matrix and lithium salt, adding a solvent to dissolve the polymer and lithium salt, and then adding the conductive ceramic powder. After stirring and dispersing the mixture evenly, a slurry of a certain viscosity is formed. The evenly stirred and dispersed slurry is applied to a release film using a scraper, dried naturally for 30 minutes, and then dried in a vacuum drying oven at 80°C for 8 hours.

[0066] In the present invention, the release film may be any of the release films commonly used for preparing solid electrolyte membranes, for example, a polyethylene terephthalate (PET) release film.

[0067] In some specific embodiments, the positive electrode side polymer matrix may include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyacrylonitrile (PAN), and polypropylene carbonate (PPC), preferably polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP). The weight average molecular weight of the positive electrode side polymer matrix (e.g., polyvinylidene fluoride-hexafluoropropylene copolymer) may be 100K-500K, such as 100K, 200K, 300K, 400K, 500K, etc., preferably 400K.

[0068] In some specific embodiments, the lithium salt may include one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalatoborate) (LiBOB), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6), preferably (LiTFSI).

[0069] In some specific embodiments, the first conductive ceramic powder can be one or more of lithium lanthanum titanate (LLTO) powder, lithium lanthanum zirconate (LLZO) powder, lithium lanthanum zirconate tantalum (LLZTO) powder, and lithium aluminum titanium phosphate (LATP) powder, preferably LLZO. The first conductive ceramic powder can have a particle size of 20-1000 nm, preferably 300 nm.

[0070] In some embodiments, the solvent can be one or more of N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetone, and dimethyl sulfoxide (DMSO), preferably DMF. The amount of the solvent used can be, for example, 2-15 times, preferably 3-10 times, the weight of the matrix polymer.

[0071] In some specific embodiments, the viscosity of the solid electrolyte slurry on the positive electrode side can be 180-250 mPa·s, for example, 185 mPa·s, 190 mPa·s, 195 mPa·s, 200 mPa·s, 205 mPa·s, 210 mPa·s, 215 mPa·s, 220 mPa·s, 225 mPa·s, 230 mPa·s, 235 mPa·s, 240 mPa·s or 245 mPa·s, etc.

[0072] In some specific embodiments, the coating thickness of the solid electrolyte slurry on the positive electrode side may be 30-100 μm, and the thickness of the solid electrolyte layer on the positive electrode side after drying may be 5 μm-20 μm.

[0073] For example, in step (2), a solid electrolyte slurry on the negative electrode side is prepared, and the negative electrode side polymer matrix (for example, polyethylene oxide PEO), succinonitrile, lithium salt, and lithium lanthanum zirconium oxide LLZO conductive ceramic powder as the second conductive ceramic powder are uniformly mixed using acetonitrile as a solvent, for example, by ball milling in a ball mill to uniformly disperse the mixture.

[0074] In some specific embodiments, the negative electrode side polymer matrix may include one or more of polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide. The viscosity-average molecular weight of the negative electrode side polymer matrix (e.g., polyethylene oxide PEO) may be 600K-10000K, such as 600K, 2000K, 4000K, 5000K, 7900K, 10000K, etc., preferably 7900K.

[0075] In some specific embodiments, the lithium salt may include one or more of LiTFSI, LiFSI, LiDFOB, LiBOB, LiClO4, LiAsF6, and LiPF6, preferably LiTFSI.

[0076] In some specific embodiments, the particle size of the lithium lanthanum zirconium oxide (LLZO) conductive ceramic powder used as the second conductive ceramic powder may be 20-1000 nm, preferably 300 nm.

[0077] In some specific embodiments, the viscosity of the solid electrolyte slurry on the negative electrode side can be 180-250 mPa·s, for example, 185 mPa·s, 190 mPa·s, 195 mPa·s, 200 mPa·s, 205 mPa·s, 210 mPa·s, 215 mPa·s, 220 mPa·s, 225 mPa·s, 230 mPa·s, 235 mPa·s, 240 mPa·s or 245 mPa·s, etc.

[0078] Specifically, in step (3), the two electrolytes are composited into a film. The uniformly dispersed negative electrode side electrolyte slurry prepared in step (2) is scraped onto the positive electrode side solid electrolyte layer prepared in step (1). It is then placed in a fume hood and dried naturally for 10 minutes to 1 hour to volatilize the solvent on the surface, and then placed in a vacuum drying oven at 50-80°C for 5-20 hours. The dried organic-inorganic composite electrolyte membrane is torn off from the release film and rolled using a roller press. The thickness after rolling is, for example, 70-90% of the thickness before rolling, preferably 80%.

[0079] The coating thickness of the solid electrolyte slurry on the negative electrode side can be 30-100 μm, and the thickness of the solid electrolyte slurry on the negative electrode side after drying can be 5 μm-20 μm.

[0080] The third aspect of the present invention provides the use of the double-layer solid electrolyte membrane of the first aspect of the present invention or the double-layer solid electrolyte membrane obtained by the preparation method of the second aspect of the present invention in a solid-state lithium metal battery.

[0081] A fourth aspect of the present invention provides a solid-state lithium metal battery, comprising the double-layer solid electrolyte membrane of the first aspect of the present invention or the double-layer solid electrolyte membrane prepared by the preparation method of the second aspect of the present invention. Preferably, the solid-state lithium metal battery is a semi-solid-state battery. A semi-solid-state battery refers to a solid-state battery in which liquid accounts for 1-10% by mass of the battery.

[0082] Example

[0083] The present invention is described in detail below by way of examples, which are not intended to limit the present invention. The experimental methods in the following examples are conventional methods unless otherwise specified.

[0084] In the following examples, the weight average molecular weight of the PVDF-HFP used is 400K; the viscosity average molecular weight of PEO is 7900K; and the particle size of the LLZO ceramic powder is 300 nm.

[0085] Example 1

[0086] This embodiment provides a double-layer solid electrolyte membrane, as shown in FIG1 . The double-layer solid electrolyte membrane includes a positive electrode side solid electrolyte layer 1 and a negative electrode side solid electrolyte layer 2 .

[0087] The positive electrode side solid electrolyte layer 1 is composed of PVDF-HFP, LiTFSI and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the positive electrode side solid electrolyte layer 1 are: 60 parts of PVDF-HFP, 25 parts of LiTFSI and 15 parts of LLZO ceramic powder.

[0088] The negative electrode side solid electrolyte layer 2 is composed of PEO and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the negative electrode side solid electrolyte layer 2 are: 1 part of PEO and 99 parts of LLZO ceramic powder.

[0089] First, the positive electrode side solid electrolyte slurry was prepared according to the following preparation steps (1).

[0090] 60 parts by weight of PVDF-HFP as the matrix polymer was mixed with 25 parts by weight of the lithium salt LiTFSI and dissolved in DMF as the solvent, with the DMF used being four times the weight of the PVDF-HFP. Once completely dissolved, 15 parts by weight of LLZO ceramic powder was added. After stirring and dispersing evenly, a 30 μm thick film was applied using a scraper onto a PET release film. The film was then air-dried in a fume hood for 30 minutes to evaporate the surface solvent, and then dried in a vacuum drying oven at 80°C for 8 hours before use.

[0091] Next, the negative electrode side solid electrolyte slurry was prepared according to the following preparation step (2).

[0092] 1 part PEO as the second layer matrix polymer was mixed with 99 parts LLZO ceramic powder, and acetonitrile was used as the solvent, with the amount of acetonitrile being 40 times the mass of PEO. The mixed slurry was placed in a high-energy ball mill for ball milling and dispersion.

[0093] Then, a double-layer solid electrolyte membrane was prepared according to the following preparation step (3).

[0094] The uniformly dispersed negative electrode solid electrolyte slurry prepared in step (2) was scraped onto the positive electrode solid electrolyte layer prepared in step (1) to a thickness of 30 μm. The slurry was then placed in a fume hood and dried naturally for 30 minutes to evaporate the surface solvent. The membrane was then placed in a vacuum drying oven at 60°C and dried for 8 hours. The dried organic-inorganic composite electrolyte membrane was peeled off from the PET release film and rolled using a roller press.

[0095] In the double-layer solid electrolyte membrane finally obtained, the thickness of the solid electrolyte layer on the positive electrode side was 10 μm, and the thickness of the solid electrolyte layer on the negative electrode side was 15 μm.

[0096] Example 2

[0097] This embodiment provides a double-layer solid electrolyte membrane, as shown in FIG1 . The double-layer solid electrolyte membrane includes a positive electrode side solid electrolyte layer 1 and a negative electrode side solid electrolyte layer 2 .

[0098] The positive electrode side solid electrolyte layer 1 is composed of PVDF-HFP, LiTFSI and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the positive electrode side solid electrolyte layer 1 are: 60 parts of PVDF-HFP, 25 parts of LiTFSI and 15 parts of LLZO ceramic powder.

[0099] The negative electrode side solid electrolyte layer 2 is composed of PEO, LiTFSI, succinonitrile and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the negative electrode side solid electrolyte layer 2 are: 6 parts of PEO, 3 parts of LiTFSI, 2 parts of succinonitrile and 89 parts of LLZO ceramic powder.

[0100] First, the positive electrode side solid electrolyte slurry was prepared according to the following preparation steps (1).

[0101] 60 parts by weight of PVDF-HFP as the matrix polymer was mixed with 25 parts by weight of LiTFSI, and dissolved in DMF (4 times the weight of PVDF). Once completely dissolved, 15 parts by weight of LLZO ceramic powder was added. After stirring and dispersing evenly, a 30 μm-thick film was applied to a PET release film using a doctor blade. The film was then air-dried in a fume hood for 30 minutes to evaporate the surface solvent. The film was then dried in a vacuum drying oven at 80°C for 8 hours before use.

[0102] Next, the negative electrode side solid electrolyte slurry was prepared according to the following preparation step (2).

[0103] 6 parts of PEO (polyethylene glycol) as the second layer matrix polymer was mixed with 3 parts of lithium salt LiTFSI, 2 parts of succinonitrile, and 89 parts of LLZO ceramic powder. Acetonitrile was used as the solvent, with the amount of acetonitrile being 40 times the mass of the PEO. The mixed slurry was placed in a high-energy ball mill for ball milling and dispersion.

[0104] Then, a double-layer solid electrolyte membrane was prepared according to the following preparation step (3).

[0105] The uniformly dispersed negative electrode solid electrolyte slurry prepared in step (2) was scraped onto the positive electrode solid electrolyte layer prepared in step (1) to a thickness of 30 μm. The slurry was then placed in a fume hood and dried naturally for 30 minutes to evaporate the surface solvent. The membrane was then placed in a vacuum drying oven at 60°C and dried for 8 hours. The dried organic-inorganic composite electrolyte membrane was peeled off from the PET release film and rolled using a roller press.

[0106] In the double-layer solid electrolyte membrane finally obtained, the thickness of the solid electrolyte layer on the positive electrode side was 10 μm, and the thickness of the solid electrolyte layer on the negative electrode side was 15 μm.

[0107] Example 3

[0108] This embodiment provides a double-layer solid electrolyte membrane, as shown in FIG1 . The double-layer solid electrolyte membrane includes a positive electrode side solid electrolyte layer 1 and a negative electrode side solid electrolyte layer 2 .

[0109] The positive electrode side solid electrolyte layer 1 is composed of PVDF-HFP, LiTFSI and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the positive electrode side solid electrolyte layer 1 are: 60 parts of PVDF-HFP, 25 parts of LiTFSI and 15 parts of LLZO ceramic powder.

[0110] The negative electrode side solid electrolyte layer 2 is composed of PEO, LiTFSI, succinonitrile and LLZO ceramic powder, wherein the mass parts of the above components relative to the total mass of the negative electrode side solid electrolyte layer 2 are: 10 parts of PEO, 8 parts of LiTFSI, 2 parts of succinonitrile and 80 parts of LLZO ceramic powder.

[0111] First, the positive electrode side solid electrolyte slurry was prepared according to the following preparation steps (1).

[0112] 60 parts by weight of PVDF-HFP as the matrix polymer was mixed with 25 parts by weight of the lithium salt LiTFSI and dissolved in DMF as the solvent, with the DMF used being four times the weight of the PVDF-HFP. Once completely dissolved, 15 parts by weight of LLZO ceramic powder was added. After stirring and dispersing evenly, a 30 μm thick film was applied using a scraper onto a PET release film. The film was then air-dried in a fume hood for 30 minutes to evaporate the surface solvent, and then dried in a vacuum drying oven at 80°C for 8 hours before use.

[0113] Next, the negative electrode side solid electrolyte slurry was prepared according to the following preparation step (2).

[0114] 10 parts of PEO (polyethylene glycol) as the second layer matrix polymer was mixed with 8 parts of lithium salt LiTFSI, 2 parts of succinonitrile, and 80 parts of LLZO ceramic powder. Acetonitrile was used as the solvent, with the amount of acetonitrile being 40 times the mass of the PEO. The mixed slurry was placed in a high-energy ball mill for ball milling and dispersion.

[0115] Then, a double-layer solid electrolyte membrane was prepared according to the following preparation step (3).

[0116] The uniformly dispersed negative electrode solid electrolyte slurry prepared in step (2) was scraped onto the positive electrode solid electrolyte layer prepared in step (1) to a thickness of 30 μm. The slurry was then placed in a fume hood and dried naturally for 30 minutes to evaporate the surface solvent. The membrane was then placed in a vacuum drying oven at 60°C and dried for 8 hours. The dried organic-inorganic composite electrolyte membrane was peeled off from the PET release film using a roller press.

[0117] In the double-layer solid electrolyte membrane finally obtained, the thickness of the solid electrolyte layer on the positive electrode side was 10 μm, and the thickness of the solid electrolyte layer on the negative electrode side was 15 μm.

[0118] The following comparative examples prepared a single-layer solid electrolyte membrane, that is, it did not include the positive electrode side electrolyte layer shown in FIG1 , but only included the negative electrode side electrolyte layer.

[0119] Comparative Example 1

[0120] This comparative example provides a single-layer solid electrolyte, that is, it does not include the positive electrode side electrolyte layer shown in FIG1 , but only includes the negative electrode side electrolyte layer.

[0121] 4 parts of PEO as the matrix polymer were mixed with 2 parts of lithium salt LiTFSI, 2 parts of succinonitrile, and 92 parts of LLZO ceramic powder. Acetonitrile was used as the solvent, with the amount of acetonitrile being 40 times the mass of the PEO. The mixed slurry was placed in a high-energy ball mill for ball milling and dispersion.

[0122] The evenly dispersed slurry was then cast onto a PTFE evaporating dish, allowed to air dry for 30 minutes in a fume hood to evaporate the solvent on the surface, and then dried in a vacuum drying oven at 80°C for 8 hours. This resulted in a single-layer solid electrolyte membrane with a thickness of 100 μm.

[0123] Comparative Example 2

[0124] This comparative example provides a single-layer solid electrolyte, that is, it does not include the positive electrode side electrolyte layer shown in FIG1 , but only includes the negative electrode side electrolyte layer.

[0125] 10 parts of PEO as the matrix polymer was mixed with 8 parts of lithium salt LiTFSI, 2 parts of succinonitrile, and 80 parts of LLZO ceramic powder. Acetonitrile was used as the solvent, with the amount of acetonitrile being 40 times the mass of PEO. The mixed slurry was placed in a high-energy ball mill for ball milling and dispersion.

[0126] The evenly dispersed slurry was then cast onto a PTFE evaporating dish, allowed to air dry for 30 minutes in a fume hood to evaporate the solvent on the surface, and then dried in a vacuum drying oven at 80°C for 8 hours. This resulted in a single-layer solid electrolyte membrane with a thickness of 100 μm.

[0127] evaluate

[0128] Optical images of the solid electrolyte membranes formed according to Examples 1 to 3 and Comparative Examples 1 to 2 were observed to evaluate the membrane formation. Furthermore, the electrochemical windows of the solid electrolyte membranes formed according to Examples 1 to 3 and Comparative Examples 1 to 2 were measured to evaluate the oxidation resistance of the electrolyte membranes.

[0129] 1, 2, and 3 in FIG2 correspond to the double-layer solid electrolyte membranes of Example 1, Example 2, and Example 3, respectively, while 1 and 2 in FIG3 correspond to the single-layer solid electrolyte membranes of Comparative Example 1 and Comparative Example 2, respectively.

[0130] Table 1

[0131] It can be seen from the results of Figures 2, 3 and Table 1 that, as shown in Figure 2, using the double-layer structure solid electrolyte membrane design according to Examples 1 to 3 of the present invention, the negative electrode side solid electrolyte with a high content of LLZO can be tightly attached to the positive electrode side solid electrolyte. This double-layer electrolyte design ensures that the negative electrode side solid electrolyte with a high LLZO ceramic content can be attached to the positive electrode side solid electrolyte with a low content of LLZO ceramic to form an independent film. Therefore, this double-layer structure design can not only produce solid electrolyte membranes on a large scale by roll-to-roll, but also the electrolyte membrane has higher oxidation resistance, can match high-voltage positive electrode materials, and achieve a higher energy density solid-state battery. Moreover, the double-layer structure solid electrolyte membrane according to this embodiment can be bent and folded, and has excellent flexibility. As can be seen from Figure 3, despite the increase in the polymer (PEO) content (Comparative Example 2), the LLZO solid electrolyte of this comparative example is too brittle and the electrolyte cannot form a film. And it can be seen from Figure 4 that the electrochemical window of the solid electrolyte membrane with a double-layer design is wider than that of the single-layer solid electrolyte membrane.

[0132] The above examples are used to describe exemplary embodiments of the present invention, but the present invention is not limited thereto. It should be understood by those skilled in the art that the above examples are for illustrative purposes only, and the specific embodiments and examples of the present invention should not be construed as limiting the scope of the present invention. The embodiments can be changed and modified within the scope of the present invention, and such changes and modifications should fall within the scope of protection of the present invention.

Claims

1. A double-layer solid electrolyte membrane, characterized in that: The double-layer solid electrolyte membrane comprises a positive electrode side solid electrolyte layer and a negative electrode side solid electrolyte layer. The positive electrode side solid electrolyte layer comprises a positive electrode side polymer matrix, a lithium salt and a first conductive ceramic powder, and the content of the first conductive ceramic powder is 5 mass % to 20 mass % relative to the total mass of the positive electrode side solid electrolyte layer, and Among them, the negative electrode side solid electrolyte layer comprises a negative electrode side polymer matrix, optional succinonitrile, optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80 mass % to 99 mass % relative to the total mass of the negative electrode side solid electrolyte layer.

2. The double-layer solid electrolyte membrane according to claim 1, wherein: The positive electrode side polymer matrix is ​​one or more selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polypropylene carbonate, preferably polyvinylidene fluoride-hexafluoropropylene copolymer, and / or, The lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium bis(oxalatoborate), lithium perchlorate, lithium hexafluoroarsenate, and lithium hexafluorophosphate, preferably lithium bis(trifluoromethanesulfonyl)imide, and / or The first conductive ceramic powder is selected from one or more of lithium lanthanum titanium oxide powder, lithium lanthanum zirconium oxide powder, lithium lanthanum zirconium tantalum oxide powder, and lithium aluminum titanium phosphorus powder, preferably lithium lanthanum zirconium oxide powder.

3. The double-layer solid electrolyte membrane according to claim 1 or 2, wherein: The negative electrode side polymer matrix is ​​one or more selected from polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide.

4. The double-layer solid electrolyte membrane according to any one of claims 1 to 3, wherein Relative to the total mass of the positive electrode side solid electrolyte layer, the content of the positive electrode side polymer matrix is ​​60 mass % to 85 mass %, and / or the content of the lithium salt is 10 mass % to 35 mass %, and / or the content of the first conductive ceramic powder is 5 mass % to 20 mass %.

5. The double-layer solid electrolyte membrane according to any one of claims 1 to 4, wherein Relative to the total mass of the solid electrolyte layer on the negative electrode side, the content of the negative electrode side polymer matrix is ​​1 mass % to 20 mass %, and / or the content of succinonitrile is 0 mass % to 5 mass %, and / or the content of the lithium salt is 0 mass % to 10 mass %, and / or the content of the second conductive ceramic powder is 80 mass % to 99 mass %.

6. The double-layer solid electrolyte membrane according to any one of claims 1 to 5, wherein The positive electrode side solid electrolyte layer and the negative electrode side solid electrolyte layer each independently contain a plasticizer, Wherein, the plasticizer is selected from one or more of polyethylene glycol, ethylene carbonate, butyl benzyl phthalate, and propylene carbonate.

7. The double-layer solid electrolyte membrane according to any one of claims 1 to 6, wherein The particle size of the first conductive ceramic powder is 20 to 1000 nm, preferably 300 nm; and / or the particle size of the second conductive ceramic powder is 20 to 1000 nm, preferably 300 nm; Preferably, the thickness of the positive electrode side solid electrolyte layer is 5 to 20 μm, and the thickness of the negative electrode side solid electrolyte layer is 5 to 20 μm.

8. A method for preparing a double-layer solid electrolyte membrane, characterized in that: The preparation method comprises the following steps: (1) preparing a positive electrode side solid electrolyte slurry, coating the prepared positive electrode side solid electrolyte slurry on a release film by scraping and drying to form a positive electrode side solid electrolyte layer; (2) preparing a negative electrode side solid electrolyte slurry, applying the prepared negative electrode side solid electrolyte slurry on the positive electrode side solid electrolyte layer by scraping and drying to form a negative electrode side solid electrolyte layer and then forming a double-layer solid electrolyte membrane; (3) peeling the double-layer solid electrolyte membrane from the release film and subjecting it to a pressure treatment, The positive electrode side solid electrolyte slurry comprises a positive electrode side polymer matrix, a lithium salt and a first conductive The content of the first conductive ceramic powder is 5 mass % to 20 mass % relative to the total dry weight of the positive electrode side solid electrolyte slurry, and Among them, the solid electrolyte slurry on the negative electrode side comprises a negative electrode side polymer matrix, optional succinonitrile, optional lithium salt and a second conductive ceramic powder, the second conductive ceramic powder is lithium lanthanum zirconium oxide conductive ceramic powder, and the content of the second conductive ceramic powder is 80 mass% to 99 mass% relative to the total dry basis mass of the solid electrolyte slurry on the negative electrode side.

9. The preparation method according to claim 8, wherein: The positive electrode side polymer matrix is ​​one or more selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polypropylene carbonate, preferably polyvinylidene fluoride-hexafluoropropylene copolymer, and / or, The lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate, lithium bis(oxalatoborate), lithium perchlorate, lithium hexafluoroarsenate, and lithium hexafluorophosphate, preferably lithium bis(trifluoromethanesulfonyl)imide, and / or The first conductive ceramic powder is selected from one or more of lithium lanthanum titanium oxide powder, lithium lanthanum zirconium oxide powder, lithium lanthanum zirconium tantalum oxide powder, and lithium aluminum titanium phosphorus powder, preferably lithium lanthanum zirconium oxide powder.

10. The preparation method according to claim 8 or 9, wherein: The negative electrode side polymer matrix is ​​one or more selected from polyethylene oxide, polyethylene glycol, polypropylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polypropylene carbonate, preferably polyethylene oxide.

11. The preparation method according to any one of claims 8 to 10, wherein Relative to the total dry mass of the positive electrode side solid electrolyte slurry, the content of the positive electrode side polymer matrix is ​​60 mass % to 85 mass %, and / or the content of the lithium salt is 10 mass % to 35 mass %, and / or the content of the first conductive ceramic powder is 5 mass % to 20 mass %.

12. The preparation method according to any one of claims 8 to 11, wherein Relative to the total dry mass of the solid electrolyte slurry on the negative electrode side, the content of the negative electrode side polymer matrix is ​​1 mass % to 20 mass %, and / or the content of the succinonitrile is 0 mass % to 5 mass %, and / or the content of the lithium salt is 0 mass % to 10 mass %, and / or the content of the second conductive ceramic powder is 80 mass % to 99 mass %.

13. The preparation method according to any one of claims 8 to 12, wherein The viscosity of the positive electrode side solid electrolyte slurry and the negative electrode side solid electrolyte slurry is independently 180-250 mPa·s.

14. The preparation method according to any one of claims 8 to 13, wherein The coating thickness of the positive electrode side solid electrolyte slurry is 30-100 μm, and the thickness of the positive electrode side solid electrolyte layer after drying is 5-20 μm, and The coating thickness of the solid electrolyte slurry on the negative electrode side is 30-100 μm, and the thickness of the solid electrolyte layer on the negative electrode side after drying is 5-20 μm.

15. Use of the double-layer solid electrolyte membrane according to any one of claims 1 to 7 or the double-layer solid electrolyte membrane obtained by the preparation method according to any one of claims 8 to 14 in a solid-state lithium metal battery.

16. A solid-state lithium metal battery, characterized in that: The solid-state lithium metal battery comprises a double-layer solid electrolyte membrane according to any one of claims 1 to 7 or a double-layer solid electrolyte membrane obtained by the preparation method according to any one of claims 8 to 14; Preferably, the solid-state lithium metal battery is a semi-solid-state battery.

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