Electrolyte membrane, wet preparation method thereof and application thereof

Abstract

The application provides an electrolyte membrane and a wet preparation method and application thereof, and comprises a first electrolyte layer, a second electrolyte layer and a third electrolyte layer which are sequentially stacked, each electrolyte layer comprising a solid electrolyte and a binder; in the second electrolyte layer, the uniformity of the binder is 20%-40%; the uniformity of the binder in the first electrolyte layer and the third electrolyte layer is greater than that in the second electrolyte layer, and the difference in uniformity is greater than 10%. The electrolyte membrane and the wet preparation method and application thereof can balance the ion transmission performance of the electrolyte membrane and the interface adhesion between the electrolyte membrane and the electrode, thereby improving the capacity and rate performance of the full solid-state battery.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to an electrolyte membrane and a wet preparation method and application thereof. Background Art

[0002] With the rapid development of new energy vehicles and 5G communication technology, higher requirements are being placed on the safety, energy density and cycle performance of lithium-ion batteries. However, the electrolytes currently used in commercial lithium-ion battery electrolytes have safety hazards such as leakage, swelling, corrosion and flammability. By replacing flammable liquid electrolytes with solid electrolyte membranes, users can be provided with safer next-generation power batteries with higher energy density and better long-term cycle performance. The solid electrolyte membrane is located between the positive and negative electrodes of the lithium-ion battery. It mainly isolates the positive and negative active materials, prevents short circuits, and provides a good ion transmission channel. The performance of the solid electrolyte membrane directly affects the battery's capacity, cycle life, safety performance and other characteristics. Therefore, improving the performance of the solid electrolyte membrane is very important for improving the overall performance of the battery.

[0003] Wet-process preparation can reduce the thickness of solid electrolyte membranes to as low as 10μm, which is beneficial for improving the energy density of all-solid-state batteries. However, problems such as binder agglomeration and side reactions between the solid electrolyte and the solvent are prone to occur during the preparation process, which limits the optimization of solid electrolyte membranes. Summary of the Invention

[0004] The present invention proposes an electrolyte membrane and its wet preparation method and application. Through the electrolyte membrane and its wet preparation method and application provided by the present invention, the ion transport performance of the electrolyte membrane and the interface adhesion between the electrolyte membrane and the positive electrode sheet or the negative electrode sheet can be taken into account. On the basis of improving the ionic conductivity, the peeling strength between the electrolyte membrane and the electrode is improved.

[0005] To solve the above technical problems, the present invention provides an electrolyte membrane comprising a first electrolyte layer, a second electrolyte layer and a third electrolyte layer stacked in sequence, wherein each electrolyte layer comprises a solid electrolyte and a binder;

[0006] In the second electrolyte layer, the uniformity of the binder is 20%-40%; the uniformity of the binder in the first electrolyte layer and the third electrolyte layer is greater than the uniformity of the binder in the second electrolyte layer, and the difference in uniformity is greater than 10%.

[0007] In one embodiment of the present invention, the first electrolyte layer includes a first binder, and the uniformity of the first binder in the first electrolyte layer is 50%-60%;

[0008] And / or, the third electrolyte layer includes a third binder, and the uniformity of the third binder in the third electrolyte layer is 50%-60%;

[0009] And / or, the peel strength between the electrolyte membrane and the positive electrode sheet or the negative electrode sheet is 20N / m-30N / m.

[0010] In one embodiment of the present invention, the binder is selected from one or more combinations of styrene-butadiene rubber, sodium alginate, polyacrylonitrile, polyurethane, polyacrylic acid, ethylene-propylene-diene monomer, styrene-butadiene rubber, polyvinylidene fluoride, fluororubber or nitrile rubber.

[0011] In one embodiment of the present invention, in each electrolyte layer, the content of the binder is 2wt%-4wt%, and the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte and a halide solid electrolyte.

[0012] In one embodiment of the present invention, the thickness of the electrolyte membrane is 10μm-20μm, the thickness of the first electrolyte layer is 10%-20% of the total thickness of the electrolyte membrane, the thickness of the second electrolyte layer is 60%-80% of the total thickness of the electrolyte membrane, and the thickness of the third electrolyte layer is 10%-20% of the total thickness of the electrolyte membrane.

[0013] The present invention also provides a wet process for preparing an electrolyte membrane, comprising at least the following steps:

[0014] Dissolving the first binder, the second binder and the third binder in the first solvent, the second solvent and the third solvent respectively to obtain a first glue solution, a second glue solution and a third glue solution;

[0015] adding a solid electrolyte to the first glue solution, the second glue solution, and the third glue solution, respectively, and adding a fourth solvent, a fifth solvent, and a sixth solvent to a target solid content, respectively, to obtain a first slurry, a second slurry, and a third slurry;

[0016] The third slurry, the second slurry and the first slurry are sequentially coated on the surface of the substrate and dried to obtain the electrolyte membrane in which the third electrolyte layer, the second electrolyte layer and the first electrolyte layer are sequentially stacked.

[0017] In one embodiment of the present invention, the polarity parameters of the first solvent, the second solvent, and the third solvent are 2.4-4, and the first solvent, the second solvent, and the third solvent are each selected from at least one of butyl butyrate, benzene, and ethylene dichloride;

[0018] The polar parameter of the fourth solvent, the fifth solvent and the sixth solvent is 0-0.2, and each of the fourth solvent, the fifth solvent and the sixth solvent is selected from at least one of trimethylpentane, dodecane, methylcyclohexane or decahydronaphthalene.

[0019] In an embodiment of the present application, the mass ratio of the solvent added before and after the solid-state electrolyte in the single slurry is 1:X2, and the uniformity of the binder in the obtained electrolyte layer is X1%, and the following relationship is satisfied: 6.5≤X2+0.1X1≤7.5.

[0020] In an embodiment of the present application, the mass ratio of the first solvent and the fourth solvent is 1:(1-2);

[0021] The mass ratio of the second solvent and the fifth solvent is 1:(3-5);

[0022] The mass ratio of the third solvent and the sixth solvent is 1:(1-2).

[0023] In an embodiment of the present application, the solid content of each of the first slurry, the second slurry and the third slurry is 50wt%-80wt%;

[0024] And / or; the drying includes a first stage and a second stage, the drying temperature of the first stage is 60-80℃, and the drying time is 1-5min, the drying temperature of the second stage is 100-120℃, and the drying time is 1-2h;

[0025] And / or; the substrate is selected from at least one of a bright aluminum foil, a bright copper foil, a polyester substrate or a release paper.

[0026] The present application also provides a full solid-state battery, comprising:

[0027] A positive electrode sheet;

[0028] A negative electrode sheet; and

[0029] An electrolyte membrane arranged between the positive electrode sheet and the negative electrode sheet, selected from the electrolyte membrane described in the above item, or obtained according to the wet preparation method described in the above item, and the first electrolyte layer of the electrolyte membrane is close to the side of the positive electrode sheet.

[0030] In summary, the present invention proposes an electrolyte membrane and its wet preparation method and application. By setting three electrolyte layers and controlling the uniformity of the binder in the three layers, by reducing the uniformity of the binder in the middle second electrolyte layer and controlling the uniformity of the binder in the electrolyte layers on both sides, the porosity of the first electrolyte layer and the third electrolyte layer can be reduced. The low-porosity electrolyte layer can reduce interface voids, and the adhesion between the electrolyte layer and the positive electrode sheet or the negative electrode sheet can be improved through physical intercalation. By controlling the uniformity of the binder in the second electrolyte layer, the area of ​​the binder becomes smaller, thereby improving the transmission path of ions inside the electrolyte membrane, thereby taking into account the ion transmission performance of the electrolyte membrane and the interface adhesion between the electrolyte membrane and the positive electrode sheet or the negative electrode sheet. On the basis of improving the ionic conductivity, the peeling strength between the electrolyte membrane and the electrode is improved, thereby improving the capacity and rate performance of the all-solid-state battery. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0033] The technical solutions of the present invention are further described in detail below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The present invention proposes an electrolyte membrane, comprising a first electrolyte layer, a second electrolyte layer and a third electrolyte layer stacked in sequence, each electrolyte layer comprising a solid electrolyte and a binder. In the second electrolyte layer, the uniformity of the binder is 20%-40%, the uniformity of the binder in the first electrolyte layer and the third electrolyte layer is greater than the uniformity of the binder in the second electrolyte layer, and the difference in uniformity is more than 10%. Among them, the uniformity is defined as the volume coverage of the binder characteristic signal distributed in the detection area, that is, the proportion of the effective volume occupied by the binder phase to the total volume of the detection area. Through the three-layer structure design, the porosity can be reduced by controlling the uniformity of the binder in the first electrolyte layer and the third electrolyte layer. The low-porosity electrolyte layer can reduce the interface voids, and the adhesion between the electrolyte layer and the positive electrode sheet or the negative electrode sheet can be improved by physical interlocking. By controlling the uniformity of the binder in the second electrolyte layer, the area of ​​the binder becomes smaller, thereby improving the transmission path of ions inside the electrolyte membrane. This can take into account both the ion transport performance of the electrolyte membrane and the interfacial adhesion between the electrolyte membrane and the positive electrode or negative electrode, thereby improving the capacity and rate performance of the all-solid-state battery.

[0035] In one embodiment of the present invention, the first electrolyte layer includes a first binder and a solid electrolyte, and the uniformity of the first binder in the first electrolyte layer is 50%-60%. The second electrolyte layer includes a second binder and a solid electrolyte, and the uniformity of the second binder in the second electrolyte layer is 20%-40%. The third electrolyte layer includes a third binder and a solid electrolyte, and the uniformity of the third binder in the third electrolyte layer is 50%-60%. When the uniformity of the binder in the first and third electrolyte layers is 50%-60%, after assembling an all-solid-state battery using the electrolyte membrane, the peel strength between the electrolyte membrane and the positive electrode sheet or the negative electrode sheet is, for example, 20N / m-30N / m. Lower uniformity (in which case the binder is distributed in an island-like manner) can reduce the binder's blockage of ion pathways and improve ionic conductivity. Therefore, by reducing the uniformity of the binder in the middle second electrolyte layer and controlling the uniformity of the binder on both sides, while taking into account the ion transport performance of the electrolyte membrane and the interfacial adhesion between the electrolyte membrane and the electrode, the peel strength between the electrolyte membrane and the electrode can be improved while improving ionic conductivity.

[0036] In one embodiment of the present invention, the first, second, and third binders are each selected from at least one of styrene butadiene rubber (SBR), sodium alginate (Alg), polyacrylonitrile (PAN), polyurethane, polyacrylic acid (PAA), ethylene-propylene-diene monomer, styrene butadiene rubber, polyvinylidene fluoride (PVDF), fluororubber, and nitrile butadiene rubber (NBR). The binder content in each electrolyte layer is 2 wt% to 4 wt%. In other words, in this application, the type and content of the binder in the first, second, and third electrolyte layers can be the same or different. The binder content in each layer is individually adjusted to achieve balanced ion transport performance and adhesion in each layer while controlling the uniformity of the binder in each layer, thereby meeting the requirements of different electrolyte layers and improving the quality of the electrolyte membrane.

[0037] In one embodiment of the present invention, the thickness of the electrolyte membrane is, for example, 10 μm to 20 μm, and the thickness of the first electrolyte layer is, for example, 10% to 20% of the total thickness of the electrolyte membrane, the thickness of the second electrolyte layer is, for example, 60% to 80% of the total thickness of the electrolyte membrane, and the thickness of the third electrolyte layer is, for example, 10% to 20% of the total thickness of the electrolyte membrane. By increasing the thickness ratio of the second electrolyte layer while reducing the thickness ratios of the first and third electrolyte layers, the ion transport performance of the electrolyte membrane can be maximized and the interfacial adhesion with the electrode can be maintained.

[0038] In one embodiment of the present invention, the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and for example, is selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 , Li6PS5Cl, Li3InCl6 or Li3YCl6, etc. In different electrolyte layers, the solid electrolytes may be the same or different.

[0039] Based on the above-mentioned electrolyte membrane, the present invention also proposes a wet preparation method of the electrolyte membrane, which at least includes: dissolving the first binder, the second binder and the third binder in the first solvent, the second solvent and the third solvent respectively to obtain the first glue liquid, the second glue liquid and the third glue liquid; adding solid electrolyte to the first glue liquid, the second glue liquid and the third glue liquid respectively, and adding the fourth solvent, the fifth solvent and the sixth solvent to the target solid content respectively to obtain the first slurry, the second slurry and the third slurry; coating the third slurry, the second slurry and the first slurry on the surface of the substrate in sequence, and drying them to obtain an electrolyte membrane in which the third electrolyte layer, the second electrolyte layer and the first electrolyte layer are stacked in sequence.

[0040] In one embodiment of the present invention, in the first glue solution, the second glue solution and the third glue solution, the content of the binder is, for example, 1wt%-30wt% respectively, and the polarity parameters of the first solvent, the second solvent and the third solvent are, for example, 2.4-4 respectively. Further, in the present embodiment, the first solvent, the second solvent and the third solvent each include at least one of butyl butyrate, benzene or ethylene dichloride, etc., wherein the polarity parameter of butyl butyrate is, for example, 2.8, the polarity parameter of benzene is, for example, 3, and the polarity parameter of ethylene dichloride is, for example, 3.5. By controlling the polarity parameters of the first solvent, the second solvent and the third solvent, on the one hand, the first solvent, the second solvent and the third solvent can be made to have good dissolving and dispersing power to the binder, alleviate the agglomeration problem of the binder, on the other hand, the polarity of the first solvent is relatively low, can reduce the side reaction between the solvent and the solid electrolyte, thereby jointly improving the performance of the electrolyte membrane.

[0041] In an embodiment of the present application, after obtaining the first glue solution, the second glue solution and the third glue solution, solid electrolyte is added to the first glue solution, the second glue solution and the third glue solution respectively, and then the fourth solvent, the fifth solvent and the sixth solvent are added to the target solid content, and the first slurry, the second slurry and the third slurry are formed by high-speed mixing. The polarity parameters of the fourth solvent, the fifth solvent and the sixth solvent are 0-0.2, for example. Further, in this embodiment, the fourth solvent, the fifth solvent and the sixth solvent each include at least one of trimethylpentane, dodecane, methylcyclohexane or decahydronaphthalene, for example, wherein the polarity parameters of trimethylpentane, methylcyclohexane and decahydronaphthalene are all 0.1, and the polarity parameter of dodecane is 0.2, for example. During high-speed mixing, mixing is performed by a high-speed blender or the like, for example, at a mixing speed of 2000 rpm / min-3000 rpm / min, and the mixing time is 1 min-30 min, for example. The solid content in the first slurry, the second slurry and the third slurry is 50 wt%-80 wt%, for example. By adding a solution with a low polarity parameter to the glue solution, the state of the binder in the electrolyte membrane can be changed from complete disentanglement to partial disentanglement without affecting the adhesion of the binder, thereby improving the entanglement degree of the binder, and further reducing the contact area of the binder and the solid electrolyte, and reducing the influence of the intrinsic insulating binder on the ion and electron transmission in the solid electrolyte. By controlling the polarity parameters of the two added solvents, the influence of the solvent on the solid electrolyte can be reduced.

[0042] In an embodiment of the present application, in the single slurry, the mass ratio of the solvent added before and after the addition of the solid electrolyte is 1:X2, wherein X2 is 1-5, i.e. the mass ratio of the first solvent and the fourth solvent, the second solvent and the fifth solvent, and the third solvent and the sixth solvent is each 1:X2. When X2 is greater than 5, too much solvent with a low polarity parameter will cause the binder to precipitate, i.e. part of the binder cannot be dissolved, which will cause problems such as uneven slurry, powdering and cracking of the electrolyte layer. In this embodiment, the uniformity of the binder in the electrolyte layer obtained by the single slurry is X1%, and the following relationship is satisfied: 6.5≤X2+0.1X1≤7.5. X2+0.1X1 is used to quantify the relationship between the mass ratio of the solvent added before and after the addition of the solid electrolyte and the distribution state of the binder, i.e. the uniformity of the binder in the electrolyte layer and the content of the solvent with a low polarity parameter in the slurry are inversely proportional. By controlling the content of the solvent with a low polarity parameter in the slurry, the uniformity can be ensured within the set range, and the agglomeration of the binder can be avoided, and the increase of the insulating area caused by the excessive dispersion of the binder to reduce the ion transmission path can also be avoided.

[0043] In one embodiment of the present invention, the mass ratio of the first solvent to the fourth solvent is, for example, 1:(1-2), the mass ratio of the second solvent to the fifth solvent is, for example, 1:(3-5), and the mass ratio of the third solvent to the sixth solvent is, for example, 1:(1-2). By controlling the mass ratio of the solvent with a higher polarity parameter to the solvent with a lower polarity parameter in the first and second slurries to be 1:(1-2), that is, by controlling the mass ratio of the solvents added to the first and third slurries before and after the solid electrolyte is added, the uniformity of the binder in the first and third electrolyte layers can be improved. Higher uniformity can reduce porosity, and the low-porosity electrolyte layer can reduce interfacial voids, thereby improving the adhesion between the electrolyte layer and the electrode through physical intercalation. At the same time, controlling the content of the solvent with a lower polarity parameter to be greater than or equal to that of the solvent with a higher polarity parameter can avoid the problem of side reactions of the solvent with a higher polarity parameter on the solid electrolyte. By controlling the mass ratio of the solvent with a higher polarity parameter to the solvent with a lower polarity parameter in the second slurry to 1:(3-5), the uniformity of the binder in the second electrolyte layer can be reduced. This reduces the area of ​​binder, thereby improving the ion transport pathway within the electrolyte membrane, and thus enhancing the capacity and rate performance of the all-solid-state battery. To determine the maximum amount of solvent with a lower polarity parameter to add, the binder is first dissolved in the solvent with a higher polarity parameter, and then different amounts of solvent with a lower polarity parameter are added. The proportion of solvent with a lower polarity parameter at the time when the binder precipitates is the highest.

[0044] In one embodiment of the present invention, the substrate is selected from at least one of a smooth aluminum foil, a smooth copper foil, a polyester substrate, or a release paper, so that the substrate can be easily removed when assembling the battery. When forming the electrolyte membrane, the third slurry is first coated on the surface of the substrate, and then quickly transferred to a vacuum state for drying to obtain a third electrolyte layer. The second slurry is then coated on the surface of the first electrolyte layer, and then quickly transferred to a vacuum state for drying to obtain a second electrolyte layer. Finally, the first slurry is coated on the surface of the second electrolyte layer, and then quickly transferred to a vacuum state for drying to obtain a first electrolyte layer. The slurry is applied, for example, by blade coating or die extrusion coating, and the thickness of the formed electrolyte layer is controlled, for example, by controlling the solid content of the slurry or the coating thickness.

[0045] In one embodiment of the present invention, the drying includes a first stage and a second stage. The drying temperature of the first stage is, for example, 60°C-80°C, and the drying time is, for example, 1 min-5 min, so as to quickly volatilize solvents with lower polarity parameters, such as the fourth solvent, the fifth solvent, and the sixth solvent. The drying temperature of the second stage is, for example, 100°C-120°C, and the drying time is, for example, 1 h-2 h, so as to slowly volatilize solvents with higher polarity parameters in the electrolyte layer, such as the first solvent, the second solvent, and the third solvent. By adopting a gradient volatilization strategy such as staged drying, the structure of the binder in the electrolyte layer can be quickly locked, avoiding binder redistribution.

[0046] The present invention also provides an all-solid-state lithium-ion battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte membrane. The electrolyte membrane is positioned between the positive and negative electrode sheets and is selected from the aforementioned electrolyte membranes. The first electrolyte layer of the electrolyte membrane is positioned adjacent to the positive electrode sheet. In the present invention, the all-solid-state battery is, for example, a primary battery or a secondary battery. The secondary battery is, for example, a pouch cell, a prismatic cell, or a cylindrical cell. The present invention does not impose any specific restrictions on the type of all-solid-state battery.

[0047] In one embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer coated on at least one surface of the positive electrode current collector. The positive electrode current collector is, for example, a surface-treated foil of nickel, titanium, aluminum, silver, stainless steel, or carbon. In addition to foil, the positive electrode current collector may also be in the form of a film, mesh, porous material, foam, or non-woven fabric, among other forms, or any combination thereof.

[0048] In one embodiment of the present invention, the positive electrode active layer includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder can be selected based on actual needs. In this embodiment, the positive electrode active material includes, for example, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a lithium-rich manganese-based oxide. The positive electrode conductive agent is, for example, selected from at least one of conductive carbon black, acetylene black, carbon nanofibers (VGCF), carbon nanotubes (CNTs), or graphene. The positive electrode binder is, for example, selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide (PEO), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), and polyhexafluoropropylene.

[0049] In one embodiment of the present invention, the positive electrode active layer further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is further selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 , Li6PS5Cl, Li3InCl6, or Li3YCl6. In a specific embodiment of the present invention, the mass ratio of the positive electrode active material, solid electrolyte, positive electrode conductive agent, and positive electrode binder is, for example, (60-94): (5-30): (0.9-5): (0.1-5). The positive electrode active layer can be prepared by a dry method or a wet method, and this application does not impose any specific restrictions.

[0050] In one embodiment of the present invention, the negative electrode plate is, for example, an indium plate, a lithium plate, an aluminum plate, or an alloy plate composed of at least two of the above metals. In other embodiments of the present invention, the negative electrode plate further comprises, for example, a negative electrode current collector and a negative electrode active layer coated on at least one surface of the negative electrode current collector. The negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, or a stainless steel current collector, and the negative electrode active layer comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The proportions of the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder can be selected according to actual needs. In this embodiment, the negative electrode active material is selected from a graphite material, a silicon material, or a composite material composed of the two. The graphite material includes at least one of natural graphite or artificial graphite, the natural graphite includes at least one of block graphite, flake graphite, or earthy graphite, the artificial graphite includes at least one of single crystal graphite, polycrystalline graphite, pyrolytic graphite, or graphite fiber, and the silicon material includes but is not limited to silicon, silicon-carbon material, and silicon-oxygen material (SiO x , 0 <x<2)。负极导电剂例如选自导电炭黑、乙炔黑、科琴黑、碳纳米管或石墨烯等中的至少一种,负极粘结剂例如选自聚丙烯、聚四氟乙烯、聚丙烯酸酯、聚乙烯醚、聚甲基丙烯酸甲酯、聚六氟丙烯或丁苯橡胶等中的至少一种。负极活性层可以通过干法或湿法进行制备,本申请不作具体限制。

[0051] In one embodiment of the present invention, the negative electrode active layer further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is further selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10GeP2S 12 , Li6PS5Cl, Li3InCl6 or Li3YCl6, etc. When the negative electrode active layer includes a solid electrolyte, the mass ratio of the negative electrode active material, the solid electrolyte, the negative electrode conductive agent and the negative electrode binder is, for example, (55-93): (5.5-30): (1-5): (0.5-10).

[0052] In one embodiment of the present invention, to obtain an all-solid-state lithium-ion battery, the positive electrode sheet, electrolyte membrane, and negative electrode sheet are placed in a mold for assembly. Specifically, under a pressure of 300 MPa, the first electrolyte layer of the electrolyte membrane is transferred from a substrate to the surface of the positive electrode sheet. The substrate is then removed, and the negative electrode sheet is placed on the side of the third electrolyte layer for assembly. After assembly, the pressure is increased to 100 MPa, and the nuts at the top of the columns are tightened to maintain a constant pressure, thereby obtaining the all-solid-state lithium-ion battery. The assembly process is completed under an argon atmosphere or vacuum.

[0053] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0054] Example 1

[0055] Preparation of the electrolyte membrane: 0.3 g of PVDF was dissolved in 3.3 g of butyl butyrate solvent to obtain a PVDF ion-conducting adhesive solution. 9.7 g of Li6PS5Cl and 3.3 g of dodecane were added to the conductive adhesive solution. The mixture was mixed in a glove box at 2000 rpm / min for 10 min using a high-speed stirrer, followed by degassing at 500 rpm / min for 5 min to form a first slurry with a solid content of 60 wt%;

[0056] 0.3 g of PVDF was dissolved in 1.3 g of butyl butyrate solvent to obtain a PVDF ion-conducting glue solution. 9.7 g of Li6PS5Cl and 5.2 g of dodecane were added to the ion-conducting glue solution. The mixture was mixed in a glove box at 2000 rpm / min for 10 min using a high-speed stirrer, followed by degassing at 500 rpm / min for 5 min to form a second slurry with a solid content of 60 wt%;

[0057] 0.3 g of PVDF was dissolved in 3.3 g of butyl butyrate solvent to obtain a PVDF ion-conducting glue solution. 9.7 g of Li6PS5Cl and 3.3 g of dodecane were added to the conductive glue solution. The mixture was mixed in a glove box at 2000 rpm / min for 10 min using a high-speed stirrer, followed by degassing at 500 rpm / min for 5 min to form a third slurry with a solid content of 60 wt%;

[0058] Use a scraper to apply the third slurry on a smooth aluminum foil, quickly transfer it to a vacuum state, dry it at 70°C for 5 minutes, and then dry it at 110°C for 2 hours to form a third electrolyte layer. Apply the second slurry to the third electrolyte layer, repeat the drying operation to obtain the second electrolyte layer. Apply the first slurry to the second electrolyte layer, repeat the drying operation to obtain the first electrolyte layer. The thickness of the electrolyte membrane is 15μm, the thickness of the second electrolyte layer accounts for 70%, and the thickness of the first and third electrolyte layers each accounts for 15%. Among them, the polarity parameter of butyl butyrate is 2.8, and the polarity parameter of dodecane is 0.2.

[0059] Preparation of positive electrode: LiNi 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl, conductive carbon black, nanocarbon fiber (VGCF) and PVDF are mixed evenly in a mass ratio of 70:25:1.5:1.5:2, and then formed into a film by multi-roll continuous rolling. The film is then compounded with aluminum foil under pressure to obtain a positive electrode sheet with an areal capacity of 3mAh / cm 2 .

[0060] Negative electrode: Lithium-indium alloy sheet is selected as the negative electrode.

[0061] Li6PS5Cl was obtained from Shandong Xinjieneng Lithium Battery Co., Ltd., model number LPSCl. PVDF was obtained from Arkema, model number Film 302 PGM TR. All other reagents and raw materials not listed were commercially available.

[0062] Battery Preparation: Under a pressure of 300 MPa, the first electrolyte layer of the electrolyte membrane is transferred from the substrate to the surface of the positive electrode sheet. The substrate is then removed, and the negative electrode sheet is placed next to the third electrolyte layer and assembled in a mold. After assembly, the pressure is increased to 100 MPa and the nuts at the top of the columns are tightened to maintain constant pressure, resulting in an all-solid-state lithium-ion battery. The assembly process is completed under an argon atmosphere or vacuum. The diameter of the positive electrode sheet, electrolyte membrane, and negative electrode sheet is 10 mm.

[0063] Example 2

[0064] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:2, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:3, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:2. The preparation steps of other batteries are the same as those in Example 1.

[0065] Example 3

[0066] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:2, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:5, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:2. The preparation steps of other batteries are the same as those in Example 1.

[0067] Example 4

[0068] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:3, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:5, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:3. The preparation steps of other batteries are the same as those in Example 1.

[0069] Example 5

[0070] When preparing the positive electrode sheet, LNMO is used to replace LiNi 0.8 Co 0.1 Mn 0.1 O2, LNMO is specifically Li2ZrO3 coated single crystal LiNi 0.5 Mn 1.5 O4 was obtained from Xiamen Tungsten Co., Ltd., model number XW46. The other steps of preparing the battery were the same as those in Example 1.

[0071] Example 6

[0072] In the electrolyte membrane, the thickness of the second electrolyte layer accounts for 60%, and the thickness of the first electrolyte layer and the third electrolyte layer each accounts for 20%. The other steps of preparing the battery are the same as those in Example 1.

[0073] Example 7

[0074] In the electrolyte membrane, the thickness of the second electrolyte layer accounts for 80%, and the thickness of the first electrolyte layer and the third electrolyte layer each accounts for 10%. The other steps of preparing the battery are the same as those in Example 1.

[0075] Example 8

[0076] In the electrolyte membrane, the thickness of the second electrolyte layer accounts for 90%, and the thickness of the first electrolyte layer and the third electrolyte layer each accounts for 5%. The other steps of preparing the battery are the same as those in Example 1.

[0077] Example 9

[0078] In the electrolyte membrane, the thickness of the second electrolyte layer accounts for 50%, and the thickness of the first electrolyte layer and the third electrolyte layer each accounts for 25%. The other steps of preparing the battery are the same as those in Example 1.

[0079] Example 10

[0080] In the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer, the content of the binder was 4 wt % each. The other preparation steps of the battery were the same as those in Example 1.

[0081] Example 11

[0082] In the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer, the content of the binder was 4.5 wt % each. The other preparation steps of the battery were the same as those in Example 1.

[0083] Example 12

[0084] In the first electrolyte layer, the second electrolyte layer, and the third electrolyte layer, the binder is NBR. The other preparation steps of the battery are the same as those in Example 1.

[0085] Example 13

[0086] The first, second, and third solvents were each selected from ethylene dichloride, and the fourth, fifth, and sixth solvents were each selected from trimethylpentane, with the polarity parameter of ethylene dichloride being 3.5 and the polarity parameter of trimethylpentane being 0.1. The other steps for preparing the battery were the same as those in Example 1.

[0087] Example 14

[0088] The first solvent, the second solvent, and the third solvent were each selected from ethylene dichloride, and the fourth solvent, the fifth solvent, and the sixth solvent were each selected from decalin, the polarity parameter of ethylene dichloride being 3.5, and the polarity parameter of decalin being 0.1. The other steps for preparing the battery were the same as those in Example 1.

[0089] Comparative Example 1

[0090] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:1, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:1, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:1. The preparation steps of other batteries are the same as those in Example 1.

[0091] Comparative Example 2

[0092] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:4, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:4, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:4. The preparation steps of other batteries are the same as those in Example 1.

[0093] Comparative Example 3

[0094] In the first slurry, the mass ratio of the first solvent to the fourth solvent is 1:3, in the second slurry, the mass ratio of the second solvent to the fifth solvent is 1:4, and in the third slurry, the mass ratio of the third solvent to the sixth solvent is 1:3. The preparation steps of other batteries are the same as those in Example 1.

[0095] Comparative Example 4

[0096] The first solvent, the second solvent and the third solvent were each selected from N-methylpyrrolidone (NMP), and the polarity parameter of NMP was 6.7. The other steps of preparing the battery were the same as those in Example 1.

[0097] Comparative Example 5

[0098] The fourth solvent, the fifth solvent, and the sixth solvent are each acetonitrile, and the polarity parameter of acetonitrile is 6.2. The other steps of preparing the battery are the same as those in Example 1.

[0099] In the present invention, performance tests were performed on the electrolyte membranes and all-solid-state lithium-ion batteries in Examples 1-14 and Comparative Examples 1-5, and the test results were recorded.

[0100] In one embodiment of the present invention, in order to obtain the uniformity of the binder in the electrolyte membrane, the specific type of the binder in the electrolyte membrane can be confirmed by Fourier transform infrared spectroscopy (FTIR). In this application, for example, the electrolyte membrane is polished and thinned by focused ion beam (FIB) polishing technology to achieve stratification. After stratification, each electrolyte layer is used as a sample, and the binder type is determined by the peak position of the characteristic functional group. For example, when 1400 cm -1 -1000cm -1 When there is a peak at 2240cm, it indicates that the binder contains CF bond and the binder is PVDF; -1The presence of a peak near [N=C] indicates that the binder contains C≡N bonds and is therefore NBR. After determining the specific binder type, characteristic chemical bonds within the binder are selected as signature signals. For example, for NBR, the characteristic chemical bond might be a C-N bond; for PVDF, the characteristic chemical bond might be a C-F bond. The uniformity is then characterized using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Specifically, TOF-SIMS is used to observe the cross-section of the electrolyte layer. Through continuous ion beam sputtering, TOF-SIMS can peel off the electrolyte layer layer by layer to obtain cross-sections of different depths. The effective area sputtered and detected is 100μm×100μm, the total stripping depth is 80% of the total thickness of the electrolyte layer, and the single stripping step is 2% of the total thickness. From the TOF-SIMS 3D image, the volume coverage of the binder characteristic signal distributed in the detection area can be observed, that is, the proportion of the effective volume occupied by the binder phase to the total volume of the detection area, and the volume coverage is defined as the uniformity of the binder distribution in the electrolyte layer. Five areas on the same horizontal line of the same electrolyte layer are taken, with a spacing of 1mm between areas, and the average value of the binder uniformity in the five areas is taken as the final uniformity of the binder in the electrolyte layer.

[0101] In one embodiment of the present invention, the binder content is obtained by testing the characteristic element absorption peak of the binder by Fourier transform infrared spectroscopy. For example, PTFE has a unique infrared absorption peak (such as 1200 cm -1 -1300cm -1 FTIR can be used to quantitatively analyze the PTFE content, specifically the C-F bond vibration peak at the center of the membrane. Procedure: Separate the electrolyte membrane into layers, grind each layer into powder, mix the powder with KBr, and press the pellets. Alternatively, directly use ATR (attenuated total reflectance) mode to collect the sample's infrared spectrum and quantitatively analyze the PTFE content in each layer using a calibration curve or peak area integration.

[0102] In one embodiment of the present invention, peel strength has a meaning well known in the art and can be tested using instruments and methods known in the art, such as a universal material testing machine. An exemplary testing method is as follows: A composite sample of the electrolyte membrane and the positive or negative electrode sheet is cut into standard dimensions (25 mm in width and 150 mm in length). Using a universal material testing machine equipped with a 180° peeling fixture, one end of the composite sample is secured to the fixed fixture of the testing machine and the other end to the movable fixture. The testing machine parameters are set to a peel speed of 50 mm / min. The testing machine is started, and the movable fixture peels the electrolyte membrane and electrode at a constant speed. The force changes during the peeling process are recorded. The peel force is measured and converted to N / m (i.e., the ratio of the peel force to the sample width). Five parallel samples are tested, and the average peel force is calculated; the average peel force is the sum of the peel forces of the five test samples / 5.

[0103] In one embodiment of the present invention, an AC impedance spectroscopy test was performed on the electrolyte membranes prepared in the embodiment and the comparative example at 25°C and normal pressure. Specifically, an electrolyte membrane with a diameter of 1.6 cm was placed in a stainless steel fixture to construct a blocking cell with a stainless steel / electrolyte membrane / stainless steel structure. The impedance of the blocking cell was measured using an electrochemical workstation at 100 MPa using the formula: σ = L / SR b The ionic conductivity of the electrolyte membrane is calculated, where σ is the ionic conductivity of the electrolyte membrane, L is the thickness of the electrolyte membrane, S is the area of ​​the electrolyte membrane, and R b is the impedance of the electrolyte membrane at room temperature. Simultaneously, the solid electrolyte powder was pressed into a powder cake, and the ionic conductivity of the solid electrolyte powder was tested using the above method. The decrease in ionic conductivity of the electrolyte membrane relative to the solid electrolyte powder was calculated, denoted as z, in %.

[0104] In one embodiment of the present invention, in order to obtain normal temperature cycle performance, the all-solid-state lithium-ion batteries obtained in Examples 1-14 and Comparative Examples 1-5 are subjected to long-cycle charge and discharge after constant capacity at 25°C and normal pressure environment, and the number of normal temperature cycle laps is measured. The test conditions are to perform a long-cycle charge and discharge test on the battery after constant capacity, and record the first-cycle discharge specific capacity during the process. When the battery capacity reaches 80% (80% State of Health, 80% SOH) of the first-cycle capacity, the test is terminated to obtain the normal temperature cycle laps. The test voltage range is -0.615V-1.4V, the constant capacity current is 0.6mA, and the normal temperature cycle test ratio is 0.3C. For Example 5, its test method is the same as that of other embodiments and comparative examples, except that the test voltage range is 2V-4.85V.

[0105] In an embodiment of the present application, the full solid-state lithium ion battery after the normal temperature cycle test in examples 1-14 and comparative examples 1-5 was subjected to rate test at 25℃ environment, and the discharge specific capacity was measured as the rate performance under the condition of working voltage range of-0.615~1.4 V and rate of 2C. For example 5, the test method was the same as that of other examples and comparative examples, except that the test voltage range was 2V-4.85V.

[0106] Table 1, electrolyte film part parameters and battery performance in examples 1-5 and comparative examples 1-3

[0107]

[0108] As shown in Table 1, comparative examples 1-4 and comparative examples 1-2, by setting the electrolyte film with three-layer structure, and controlling the uniformity of the binder in the three-layer electrolyte layer, the adhesion of the electrolyte layer to the positive electrode sheet or the negative electrode sheet can be improved, and the ion transmission path in the electrolyte film is improved, the ion transmission performance of the electrolyte film and the adhesion of the electrolyte film to the electrode interface are considered, the peeling strength of the electrolyte film to the positive electrode sheet and the negative electrode sheet is improved, and the first circle discharge specific capacity and the cycle performance of the battery are improved.

[0109] As shown in Table 1, comparative examples 2-3, as the uniformity of the binder in the second electrolyte layer increases, and the difference between the uniformity of the binder in the first electrolyte layer and the third electrolyte layer and the uniformity of the binder in the second electrolyte layer is more than 10%, the ion transmission performance of the electrolyte film decreases, the ion conductivity of the electrolyte film relative to the solid-state electrolyte powder decreases, and the first circle discharge specific capacity and the cycle performance of the battery decrease. As shown in Table 1, comparative examples 3-4, as the uniformity of the binder in the first electrolyte layer and the third electrolyte layer increases, and the difference between the uniformity of the binder in the first electrolyte layer and the third electrolyte layer and the uniformity of the binder in the second electrolyte layer is more than 10%, the ion conductivity of the electrolyte film relative to the solid-state electrolyte powder increases, the peeling strength of the electrolyte film to the positive electrode sheet and the negative electrode sheet increases, the first circle discharge specific capacity of the battery decreases slightly, and the cycle performance of the battery increases.

[0110] As shown in Table 1, comparative example 1 and example 5, when the positive active material is different and the same electrolyte layer is used, the first circle discharge specific capacity is slightly different due to the difference of the positive active material, but the cycle performance is good. Therefore, the electrolyte film of the present application can be applied to different systems of solid-state batteries to improve the performance of the battery.

[0111] As shown in Table 1, by comparing Example 4 and Comparative Example 3, it can be seen that when the uniformity of the binder in the second electrolyte layer meets, but does not satisfy, the difference between the uniformity of the binder in the first electrolyte layer and the third electrolyte layer and the uniformity of the binder in the second electrolyte layer is greater than 10%, the ion transport performance of the electrolyte membrane and the adhesion between the electrolyte membrane and the electrode interface cannot be taken into account, resulting in deterioration of the cycle performance of the battery.

[0112] Table 2. Some parameters of electrolyte membranes and battery performance in Examples 1, 6-9

[0113]

[0114] As shown in Table 2, a comparison of Examples 1, 6, and 9 shows that as the thickness of the second electrolyte layer increases, the thickness of the first and third electrolyte layers decreases. This is because the binder in the second electrolyte layer has a low uniformity, which improves ion transport within the membrane. This reduces the decrease in ionic conductivity of the electrolyte membrane relative to the solid electrolyte powder, resulting in a decrease in first-cycle discharge capacity and rate capability, while improving cycling performance. Therefore, the thickness of the second electrolyte layer is controlled to 60%-80% of the total membrane thickness to achieve a balanced balance between first-cycle discharge capacity, rate capability, and cycling performance.

[0115] Table 3. Some parameters of electrolyte membranes and battery performance in Examples 1, 10-12

[0116]

[0117] Please refer to Table 3. By comparing Examples 1 and 10-11, it can be seen that when the type of binder is consistent and the preparation method is consistent, as the binder content increases, the transmission path of ions inside the electrolyte membrane is reduced, the ionic conductivity of the electrolyte membrane relative to the solid electrolyte powder decreases more, and the peel strength between the electrolyte membrane and the electrode increases, but the first-cycle discharge capacity and rate performance of the battery decrease. Therefore, the content of the binder in the electrolyte layer is controlled to ensure the peel strength between the electrolyte membrane and the electrode while controlling the decrease in ionic conductivity. By comparing Example 1 and Example 12, it can be seen that when the content of the binder is consistent and the preparation method is consistent, when the type of binder is changed, the ionic conductivity of the electrolyte membrane relative to the solid electrolyte powder decreases at the same rate, and the first-cycle discharge capacity, rate performance and cycle performance of the battery are close. Different binders can be selected in this application to improve the performance of the electrolyte membrane.

[0118] Table 4. Some parameters of electrolyte membranes and battery performance in Examples 1, 13-14 and Comparative Examples 4-5

[0119]

[0120] As shown in Table 4, it can be seen from Examples 1, 13-14 that when the mass ratio of the first solvent and the fourth solvent, the second solvent and the fifth solvent, and the third solvent and the sixth solvent is consistent, and the preparation method is consistent, the uniformity of the binder in the electrolyte layer is close, the ion conductivity of the electrolyte membrane relative to the solid-state electrolyte powder decreases uniformly, the peeling strength of the electrolyte membrane and the electrode is close, the first circle specific capacity and the cycle performance of the battery are close, and the different first solvents, second solvents and third solvents or the different fourth solvents, fifth solvents and sixth solvents can be selected to meet the polarity requirements to improve the performance of the electrolyte membrane.

[0121] As shown in Table 4, it can be seen from Comparative Examples 1 and 4 that when the polarity of the first solvent, the second solvent and the third solvent is too large, the solvent will react with the solid-state electrolyte, resulting in a serious decrease in the first circle specific capacity and the cycle performance of the battery. As shown in Table 4, it can be seen from Comparative Examples 1 and 5 that when the polarity of the fourth solvent, the fifth solvent and the sixth solvent is too large, the solubility of the solvent to the binder is high, the uniformity of the obtained binder is high, the number of regions of the binder is increased to reduce the ion transport path of the electrolyte membrane, the ion conductivity of the electrolyte membrane relative to the solid-state electrolyte powder decreases greatly, the first circle specific capacity of the battery is greatly reduced, and at the same time, the cycle performance of the battery is seriously decreased, and the battery quickly dives.

[0122] The application further provides an electronic device comprising at least one all-solid-state lithium ion battery. The all-solid-state lithium ion battery is used to provide electric energy. The electronic device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, etc. In an embodiment of the application, the vehicle is a new energy vehicle, which can be a pure electric vehicle, a hybrid vehicle or a range extended vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy and an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The electronic device comprises the all-solid-state lithium ion battery, and thus has the advantages of the all-solid-state lithium ion battery, which will not be described herein.

[0123] In summary, the present invention proposes an electrolyte membrane and its wet preparation method and application. By setting three electrolyte layers and controlling the uniformity of the binder in the three layers, the porosity of the first and third electrolyte layers can be reduced by reducing the uniformity of the binder in the middle second electrolyte layer and controlling the uniformity of the binder in the electrolyte layers on both sides. The low-porosity electrolyte layer can reduce interfacial voids and improve the adhesion between the electrolyte layer and the positive or negative electrode sheet through physical intercalation. By controlling the uniformity of the binder in the second electrolyte layer, the area of ​​the binder is reduced, thereby improving the ion transmission path within the electrolyte membrane, thereby taking into account both the ion transmission performance of the electrolyte membrane and the interfacial adhesion between the electrolyte membrane and the positive or negative electrode sheet. On the basis of improving ionic conductivity, the peel strength between the electrolyte membrane and the electrode is improved, thereby improving the capacity and rate performance of the all-solid-state battery. By increasing the thickness ratio of the middle second electrolyte layer while reducing the thickness ratio of the first and third electrolyte layers, the ion transmission performance of the electrolyte membrane can be maximized and the interfacial adhesion with the electrode can be maintained. During the preparation process, by using two solvents with different polarities and controlling the order of solvent addition, the solubility and dispersion of the binder are improved, the binder agglomeration problem is alleviated, and the side reactions between the solvent and the solid electrolyte are reduced, thereby jointly improving the performance of the electrolyte membrane. By controlling the content of the solvent with lower polarity parameters in the slurry, the uniformity can be ensured within the set range, which can prevent binder agglomeration and avoid the increase of insulating areas caused by excessive binder dispersion, which can lead to the loss of ion transmission paths.

[0124] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as the technical solutions formed by the mutual replacement of the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0125] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. An electrolyte membrane, characterized in that The invention comprises a first electrolyte layer, a second electrolyte layer and a third electrolyte layer stacked in sequence, wherein each electrolyte layer comprises a solid electrolyte and a binder; In the second electrolyte layer, the uniformity of the binder is 20%-40%; the uniformity of the binder in the first electrolyte layer and the third electrolyte layer is greater than the uniformity of the binder in the second electrolyte layer, and the difference in uniformity is greater than 10%, wherein the uniformity is the volume coverage of the characteristic signal of the binder distributed in the detection area, and is obtained by peeling off the electrolyte layer layer by layer using a time-of-flight secondary ion mass spectrometer; The electrolyte membrane is obtained by the following method: Dissolving the first binder, the second binder and the third binder in the first solvent, the second solvent and the third solvent respectively to obtain a first glue solution, a second glue solution and a third glue solution; adding a solid electrolyte to the first glue solution, the second glue solution, and the third glue solution, respectively, and adding a fourth solvent, a fifth solvent, and a sixth solvent to a target solid content, respectively, to obtain a first slurry, a second slurry, and a third slurry; applying the third slurry, the second slurry and the first slurry on the surface of the substrate in sequence and drying them to obtain the electrolyte membrane in which the third electrolyte layer, the second electrolyte layer and the first electrolyte layer are stacked in sequence; The polarity parameters of the first solvent, the second solvent and the third solvent are 2.4-4, The polarity parameters of the fourth solvent, the fifth solvent, and the sixth solvent are 0-0.2; In a single slurry, the mass ratio of the solvent added before and after the addition of the solid electrolyte is 1:X2, and the uniformity of the binder in the obtained electrolyte layer is X1%, then the following relationship is satisfied: 6.5≤X2+0.1X1≤7.

5.

2. The electrolyte membrane according to claim 1, wherein The first electrolyte layer includes a first binder, and a uniformity of the first binder in the first electrolyte layer is 50%-60%; And / or, the third electrolyte layer includes a third binder, and the uniformity of the third binder in the third electrolyte layer is 50%-60%; And / or, the peel strength between the electrolyte membrane and the positive electrode sheet or the negative electrode sheet is 20N / m-30N / m.

3. The electrolyte membrane according to claim 1, wherein The binder is selected from one or more combinations of styrene-butadiene rubber, sodium alginate, polyacrylonitrile, polyurethane, polyacrylic acid, ethylene-propylene-diene monomer, styrene-butadiene rubber, polyvinylidene fluoride, fluororubber or nitrile rubber.

4. The electrolyte membrane according to claim 1, wherein In each electrolyte layer, the content of the binder is 2 wt % to 4 wt %, and the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

5. The electrolyte membrane according to claim 1, wherein The thickness of the electrolyte membrane is 10μm-20μm, the thickness of the first electrolyte layer is 10%-20% of the total thickness of the electrolyte membrane, the thickness of the second electrolyte layer is 60%-80% of the total thickness of the electrolyte membrane, and the thickness of the third electrolyte layer is 10%-20% of the total thickness of the electrolyte membrane.

6. The electrolyte membrane according to claim 1, wherein The first solvent, the second solvent and the third solvent are each selected from at least one of butyl butyrate, benzene or ethylene dichloride; The fourth solvent, the fifth solvent, and the sixth solvent are each selected from at least one of trimethylpentane, dodecane, methylcyclohexane, and decalin.

7. The electrolyte membrane according to claim 1, wherein The mass ratio of the first solvent to the fourth solvent is 1:(1-2); The mass ratio of the second solvent to the fifth solvent is 1:(3-5); The mass ratio of the third solvent to the sixth solvent is 1:(1-2).

8. The electrolyte membrane according to claim 1, wherein The solid content of the first slurry, the second slurry and the third slurry is 50 wt% to 80 wt% respectively; And / or; the drying includes a first stage and a second stage, the drying temperature of the first stage is 60 ℃ -80 ℃, the drying time is 1min-5min, the drying temperature of the second stage is 100 ℃ -120 ℃, and the drying time is 1h-2h; And / or; the substrate is selected from at least one of smooth aluminum foil, smooth copper foil, polyester substrate or release paper.

9. An all-solid-state battery, characterized in that: include: Positive electrode; negative electrode; as well as An electrolyte membrane is provided between the positive electrode sheet and the negative electrode sheet, and is selected from the electrolyte membrane according to any one of claims 1 to 8, wherein the first electrolyte layer of the electrolyte membrane is close to one side of the positive electrode sheet.

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