Solid electrolyte membrane and preparation method thereof, all-solid-state battery and vehicle

Abstract

The invention relates to the technical field of all-solid-state batteries, and discloses a solid electrolyte membrane and a preparation method thereof, and a vehicle, the preparation method comprises the following steps: dispersing and mixing a binder, a cross-linking agent, a sulfide electrolyte, a photoinitiator and a solvent to obtain a preformed mixture, the binder comprising a protective group, the protective group comprising tert-butyl; at least one side of a base membrane is coated with the preformed mixture, the solid electrolyte membrane is obtained through in-situ curing treatment, and the in-situ curing treatment comprises first drying treatment, second drying treatment and ultraviolet irradiation treatment which are sequentially carried out. The solid electrolyte membrane which is uniform in texture, low in internal stress, few in membrane layer defect, high in conductivity and high in mechanical performance can be prepared.

Description

Technical Field

[0001] The present application relates to the technical field of all-solid-state batteries, and in particular, to a solid-state electrolyte membrane and a preparation method thereof, an all-solid-state battery, and a vehicle. Background Art

[0002] Solid electrolytes, as the main material of solid electrolyte membranes, are key structural materials that affect the performance of all-solid-state batteries. Among solid electrolytes, sulfide electrolytes have attracted much attention due to their high ionic conductivity. The conductivity of sulfide electrolytes can reach 10 -2 S / cm, which is close to the level of liquid electrolytes. However, the practical application of sulfide electrolytes in all-solid-state batteries still faces many challenges.

[0003] Although sulfide electrolytes have high ionic conductivity in their powdered form, their conductivity decreases significantly when fabricated into a solid electrolyte membrane compared to powdered sulfide electrolytes. Furthermore, solid electrolyte membranes made from sulfide electrolytes have low mechanical strength, making them susceptible to breakage during industrial production processes such as winding or isostatic pressing. Defective solid electrolyte membranes can lead to performance degradation or even failure of all-solid-state batteries. Therefore, the quality of solid electrolyte membranes has become a bottleneck hindering the large-scale industrialization of all-solid-state batteries.

[0004] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0005] In the first aspect of the present application, a method for preparing a solid electrolyte membrane is proposed, comprising: dispersing and mixing a binder, a cross-linking agent, a sulfide electrolyte, a photoinitiator, and a solvent to obtain a preformed mixture, wherein the binder includes a protective group, and the protective group includes a tert-butyl group; coating the preformed mixture on at least one side of a base film, and subjecting it to an in-situ curing treatment to obtain the solid electrolyte membrane, wherein the in-situ curing treatment includes a first drying treatment, a second drying treatment, and an ultraviolet light treatment performed in sequence.

[0006] The method for preparing a sulfide electrolyte membrane provided by the present application uses a pyrolyzable non-polar functional group on the binder as a protective group, reduces the polarity of the binder in the solvent during the dispersion and mixing treatment stage, and allows the binder to be evenly mixed with the sulfide electrolyte particles. In the subsequent curing process, the protective group is removed by in-situ curing treatment, so that the polar functional groups in the binder are fully exposed, thereby enhancing the bonding effect between the binder and the sulfide electrolyte particles. In addition, the present method utilizes a light-heat synergistic curing process to allow the cross-linking agent and the binder to undergo a cross-linking reaction, thereby establishing a network binder structure in the solid electrolyte membrane. This improves the mechanical strength of the prepared solid electrolyte membrane, reduces the solid electrolyte membrane's cracking and pulverization caused by stress shock due to volume changes during the charge and discharge cycle of the all-solid-state battery, and thereby improves the cycle durability of the solid electrolyte membrane in the all-solid-state battery, thereby contributing to improving the performance of the all-solid-state battery.

[0007] In some embodiments, the binder includes at least one of a tert-butyl polycarbonate, a tert-butyl acrylate, and a tert-butyl polyimide, wherein the tert-butyl polycarbonate includes at least one of a tert-butyl polycarbonate-polydimethylsiloxane block copolymer, a tert-butyl carbonate side chain grafted polycarbonate, and poly[2,2-bis(4-hydroxy-3-tert-butylphenyl)propane]; the tert-butyl acrylate includes at least one of polytert-butyl methacrylate, polytert-butyl acrylate, polytert-butyl methacrylate grafted polystyrene, and polytert-butyl acrylate grafted polystyrene; and the tert-butyl polyimide includes at least one of poly[2,2'-bis(trifluoromethyl)-4,4'-bis(4-tert-butylphenoxy)benzidine] and poly[tert-butyl 3,5-diaminobenzoate]. In this way, the bonding effect between the binder and the sulfide electrolyte can be improved, which is beneficial to improving the mechanical strength of the prepared solid electrolyte membrane and optimizing the structural changes that occur in the solid electrolyte membrane during the battery charge and discharge cycle.

[0008] In some embodiments, the mass ratio of the binder, the sulfide electrolyte, the crosslinker, and the photoinitiator in the preform mixture is (3-7):(91-95):(0.5-1.5):(0.5-1.5). This allows the preparation of a solid electrolyte membrane with excellent mechanical properties and resistance to attenuation changes caused by battery cycling.

[0009] In some embodiments, the mass ratio of the binder to the solvent is 1:(10-100). Thus, the prepared solid electrolyte membrane has fewer membrane structural deformation defects caused by stress, making the membrane structure of the solid electrolyte membrane more stable, thereby improving the mechanical stability of the prepared solid electrolyte membrane and reducing the performance degradation of the solid electrolyte membrane caused by membrane structural changes during service in the battery.

[0010] In some embodiments, the crosslinking agent includes at least one of diethylene glycol dimethyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 2-nitro-2-methylpropane. This facilitates the control of the crosslinking reaction during the preparation of the solid electrolyte membrane, thereby adjusting the mechanical strength and other properties of the prepared solid electrolyte membrane.

[0011] In some embodiments, the temperature of the first drying process is 80° C.-120° C., and the time of the first drying process is 5 hours-10 hours. This can remove the solvent in the preform mixture, facilitating the cross-linking reaction between the binder and the cross-linking agent to form a binder network structure.

[0012] In some embodiments, the second drying process is performed at a temperature of 140°C to 160°C for a time of 2 to 6 hours. This chemically changes the binder, removing the tert-butyl protecting group, fully exposing the polar groups in the binder, and maintaining the chemical stability of the sulfide electrolyte during the second drying process, thereby facilitating a full reaction with the cross-linking agent and forming a strong interaction with the sulfide electrolyte.

[0013] In some embodiments, the UV light treatment time is 30s-50s, and the UV light treatment intensity is 40mW / cm 2 -60mW / cm 2 As a result, a certain degree of cross-linking structure is formed in the prepared solid electrolyte membrane, which is beneficial to improving the mechanical properties of the solid electrolyte membrane and improving the efficiency of the production process.

[0014] In some embodiments, the sulfide electrolyte includes at least one of a ternary sulfide and a polysulfide, wherein the ternary sulfide includes Li3PS4, Li7P3S 11 At least one of the polysulfides includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 Thus, it is beneficial to prepare a solid electrolyte membrane with high conductivity and stability.

[0015] In some embodiments, the Dv50 particle size of the sulfide electrolyte is 100 nm to 20 μm, thereby improving the contact and ion transmission channels between the sulfide electrolytes during film formation, thereby improving the conductivity of the prepared solid electrolyte membrane.

[0016] In some embodiments, the solvent includes at least one of toluene, xylene, n-hexane, n-heptane, methylcyclohexane, n-octane, ether, and tetrahydrofuran, thereby allowing the binder, sulfide electrolyte, crosslinker, and photoinitiator to be fully dissolved to prepare the preform mixture.

[0017] In some embodiments, the speed of the dispersion mixing process is 100 rpm to 300 rpm, and the dispersion mixing process lasts for 1 hour to 24 hours. This allows for sufficient dispersion of the sulfide electrolyte, binder, photoinitiator, and crosslinker, facilitating the preparation of a solid electrolyte membrane with a uniform membrane structure.

[0018] In some embodiments, the dispersion and mixing process is performed in a protective atmosphere comprising at least one of an inert gas and nitrogen, thereby reducing the reaction of substances such as oxygen and water in the atmosphere with the sulfide electrolyte.

[0019] In some embodiments, the photoinitiator includes at least one of benzoin methyl ether, benzoin isopropyl ether, benzophenone, 4-methylbenzophenone, 1-hydroxycyclohexyl phenyl ketone, and 2,4-diethylthioxanthone. This can reduce the rapid accumulation of reaction heat released by the binder cross-linking reaction during the preparation process, which can lead to chemical decomposition or structural changes in the sulfide electrolyte caused by localized high temperatures. This can also reduce the impact of the film formation process on ion channels in the sulfide electrolyte and improve the conductivity of the prepared solid electrolyte membrane.

[0020] In some embodiments, the base film comprises at least one of glass, polytetrafluoroethylene, glass fiber, cellulose, polyimide, and epoxy resin, thereby facilitating the preparation of a solid electrolyte membrane with fewer defects and higher mechanical properties.

[0021] In a second aspect of the present application, the present application proposes a solid electrolyte membrane, which is prepared using the method proposed in the present application.

[0022] In a third aspect of the present application, the present application proposes an all-solid-state battery, comprising the solid electrolyte membrane proposed in the present application, or a solid electrolyte membrane prepared by the method proposed in the present application.

[0023] In a fourth aspect of the present application, the present application proposes a vehicle, which includes the all-solid-state battery proposed in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] Figure 1 These are the cycle test results of the all-solid-state battery made of the solid electrolyte membrane of Example 1 of the present application. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present application in detail. Examples of the embodiments are shown in the accompanying drawings, but unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid unnecessary lengthiness in the following description and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0027] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0028] The terms "include" and "have" in the description and claims of this application and any variations thereof are open expressions, that is, including the contents specified in this application but not excluding other contents.

[0029] In the description of this application, regardless of whether the word "about" or "approximately" is used, all numbers disclosed herein are approximate values. The value of each number may vary by less than 10% or by a reasonable difference considered by a person skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

[0030] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0032] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0033] The production process for preparing solid electrolyte membranes using sulfide electrolytes as the main raw material mainly includes dry film formation and wet film formation. The dry film formation process combines the sulfide electrolyte with a binder, followed by mixing, shearing, and repeated rolling to produce a thin film solid electrolyte membrane. This method does not require the use of solvents during the preparation process and is relatively environmentally friendly. However, since there is no solvent involved in the solid-state battery film forming process, the membrane layer of the solid electrolyte membrane has a high porosity, and the membrane layer is prone to defects and rupture. As a result, the all-solid-state battery assembled with the solid electrolyte membrane prepared by the dry film formation process is prone to short circuit problems.

[0034] The wet film-forming process involves mixing sulfide electrolyte powder with a binder and solvent to create a suspension, which is then processed into a film. In the wet film-forming process, factors such as binder selection, mechanical property control, and process compatibility have a significant impact on the structure and properties of the resulting solid electrolyte membrane.

[0035] Binders include two major categories: polar binders and non-polar binders. Polar binders are bonded to sulfide electrolyte particles through strong interaction forces such as hydrogen bonds and ionic bonds, while non-polar binders are bonded to sulfide electrolyte particles through weaker interaction forces such as van der Waals forces.

[0036] Although the binder can provide interaction with the sulfide electrolyte to assist in forming an interconnected membrane structure, new problems may arise if only the polarity of the binder and the magnitude of the interaction force between the binder and the sulfide electrolyte are considered: polar binders are highly soluble in solvents, and separation of the binder and the electrolyte is likely to occur during wet film formation; although non-polar binders can better maintain contact between electrolyte particles during film formation (compensating for the dispersion defects of polar binders), their bonding strength is lower than that of polar binders, which may lead to insufficient mechanical strength and stability of the solid electrolyte membrane.

[0037] The method for preparing a solid electrolyte membrane proposed in this application uses a binder with a certain degree of thermal decomposability. During the process of mixing the binder with the sulfide electrolyte, the binder can be evenly dispersed and mixed with the sulfide electrolyte due to the effect of the non-polar protective group on the binder. During the film formation and curing process of preparing the solid electrolyte membrane, the temperature is controlled to make the protective group on the binder detach and the polar group fully exposed. The cross-linking agent and the binder are cross-linked to form a binder network structure, and a strong interaction is formed between the binder network and the sulfide electrolyte. As a result, the binder can better form a solid electrolyte membrane with uniform texture, low internal stress, few film defects, high conductivity, and high mechanical properties with the sulfide electrolyte.

[0038] In a first aspect of the present application, the present application proposes a method for preparing a solid electrolyte membrane, comprising:

[0039] S1: Dispersing and mixing a binder, a cross-linking agent, a sulfide electrolyte, a photoinitiator, and a solvent to obtain a preformed mixture, wherein the binder includes a protective group, and the protective group includes a tert-butyl

[0040] The binder includes a protecting group, such as a tert-butyl protecting group, which has a steric hindrance effect and can adjust the polarity and non-polarity of the binder in the solvent, thereby affecting the hydrophilicity and lipophilicity of the binder in the solvent. Through the protective effect of the protecting group in the binder, the binder can exhibit a weaker polarity during the dispersion and mixing process, reducing the agglomeration of the binder and the sulfide electrolyte during the dispersion and mixing process. As a result, the binder can be fully dispersed with the sulfide electrolyte in the solvent, which is conducive to the subsequent cross-linking reaction between the binder and the cross-linking agent to form a network of cross-linked binders, so that the sulfide electrolyte and the binder cross-linked network form a stronger force per unit volume. As a result, the binder and the sulfide electrolyte, which can play a connecting and fixing role, are more evenly dispersed in the suspension system formed by mixing to prepare a preformed mixture.

[0041] In some embodiments, the binder includes at least one of a tert-butyl polycarbonate, a tert-butyl acrylate, and a tert-butyl polyimide, wherein the tert-butyl polycarbonate includes at least one of a tert-butyl polycarbonate-polydimethylsiloxane block copolymer, a tert-butyl carbonate side chain grafted polycarbonate, and poly[2,2-bis(4-hydroxy-3-tert-butylphenyl)propane]; the tert-butyl acrylate includes at least one of polytert-butyl methacrylate, polytert-butyl acrylate, polytert-butyl methacrylate grafted polystyrene, and polytert-butyl acrylate grafted polystyrene; and the tert-butyl polyimide includes at least one of poly[2,2'-bis(trifluoromethyl)-4,4'-bis(4-tert-butylphenoxy)benzidine] and poly[tert-butyl 3,5-diaminobenzoate]. The aforementioned binder has an appropriate amount of tert-butyl groups on its molecular chain. The steric hindrance of the tert-butyl groups can affect the binder's hydrophilicity and lipophilicity in the solvent, allowing the binder to swell and disperse better in the solvent, forming a relatively uniform network of binder molecular chains. Furthermore, at a certain temperature, the aforementioned binder's molecular chain can decompose upon heating, and the protective groups can separate from the binder molecular chains, thereby changing the molecular chain structure and enhancing the strong interaction between the polar groups in the binder molecular chain and the sulfide electrolyte. This can improve the bonding effect between the binder and the sulfide electrolyte, thereby improving the mechanical strength of the prepared solid electrolyte membrane and optimizing the structural changes that occur during the charge and discharge cycles of the solid electrolyte membrane during service in the battery.

[0042] In some embodiments, in the preform mixture, the mass ratio of the binder, the sulfide electrolyte, the crosslinker, and the photoinitiator is (3-7):(91-95):(0.5-1.5):(0.5-1.5). The binder, sulfide electrolyte, crosslinker, and photoinitiator are uniformly mixed and distributed in the preform mixture in the aforementioned ratios, allowing the molecular chains of the binder to fully contact the sulfide electrolyte, and the crosslinker to react with the binder to form a binder network, which can form a strong interaction with the sulfide. The photoinitiator can fully trigger the crosslinking reaction of the binder and the crosslinker throughout the preform mixture, allowing the sulfide electrolyte to combine with the binder to form a binder network structure connected by chemical bonds. In this way, a solid electrolyte membrane with good mechanical properties and resistance to attenuation changes caused by battery cycling can be prepared.

[0043] In some embodiments, the mass ratio of the binder to the solvent is 1:(10-100). When the mass ratio of the binder to the solvent is within the aforementioned range, the binder can be properly wetted in the solvent, and the binder molecular chain exhibits good flexibility in the solution, which is conducive to the binder and the sulfide electrolyte having a certain degree of ductility during the film formation process, and alleviates the internal stress accumulation of the solid electrolyte membrane caused by the preparation process. As a result, the prepared solid electrolyte membrane has fewer membrane structural deformation defects caused by stress, making the membrane structure of the solid electrolyte membrane more stable, thereby improving the mechanical stability of the prepared solid electrolyte membrane and reducing the performance degradation of the solid electrolyte membrane caused by membrane structural changes during service in the battery.

[0044] In some embodiments, the crosslinking agent includes at least one of diethylene glycol dimethyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 2-nitro-2-methylpropane. The crosslinking agent has an appropriate molecular weight, can be stably dispersed in the solvent, and undergoes a crosslinking reaction with the binder via the action of a photoinitiator to form a binder network in the solid electrolyte membrane. This facilitates the control of the crosslinking reaction during the preparation of the solid electrolyte membrane, thereby adjusting the mechanical strength and other properties of the resulting solid electrolyte membrane.

[0045] In some embodiments, the sulfide electrolyte includes at least one of a ternary sulfide and a polysulfide, wherein the ternary sulfide includes Li3PS4, Li7P3S 11 At least one of the polysulfides includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12The aforementioned sulfide electrolyte has high ionic conductivity and relatively good thermal stability, thereby reducing performance changes caused by chemical decomposition during the process. Furthermore, the aforementioned sulfide has high ionic conductivity and chemical stability, which facilitates the preparation of a solid electrolyte membrane with high conductivity and stability.

[0046] In some embodiments, the sulfide electrolyte has a Dv50 particle size of 100 nm to 20 μm. The sulfide electrolyte particle size within this range forms a certain contact surface with the binder, allowing for an appropriate contact area between the sulfide electrolytes, thereby reducing the risk of the binder completely encapsulating the sulfide electrolyte. This helps maintain contact and ion transport channels between the sulfide electrolytes during film formation, thereby improving the conductivity of the resulting solid electrolyte membrane.

[0047] In some embodiments, the solvent includes at least one of toluene, xylene, n-hexane, n-heptane, methylcyclohexane, n-octane, ether, and tetrahydrofuran. The aforementioned solvent is a non-polar solvent, so that the interaction between the binder molecular chains under the action of the protective group and the solvent molecules in the solvent is weak, thereby weakening the entanglement between the binder molecular chains and improving the dispersion effect of the binder in the solvent. In addition, the aforementioned solvent does not react with any substance in the preformed mixture, has a relatively low boiling point, and is conducive to drying and evaporation by heating. As a result, it is beneficial to reduce the adverse effects on the structure of the prepared solid electrolyte membrane caused by the subsequent removal of the solvent.

[0048] In some embodiments, the speed of the dispersion mixing process is 100 rpm to 300 rpm, and the dispersion mixing process lasts for 1 hour to 24 hours. Under the above-mentioned dispersion mixing conditions, the sulfide electrolyte, binder, photoinitiator, and cross-linking agent can be fully dispersed, which is conducive to the preparation of a solid electrolyte membrane with a uniform membrane structure.

[0049] In some embodiments, the dispersion and mixing process is performed in a protective atmosphere comprising at least one of an inert gas and nitrogen, thereby reducing the reaction of substances such as oxygen and water in the atmosphere with the sulfide electrolyte.

[0050] In some embodiments, the dispersion mixing process needs to be performed under light-shielding conditions. Since the photoinitiator can trigger a cross-linking reaction of the residual double bonds in the adhesive under light, processing in a light-shielded environment helps reduce the cross-linking reaction caused by the photoinitiator during the mixing process.

[0051] S2: coating the preformed mixture on at least one side of the base film and subjecting it to in-situ curing treatment to obtain the solid electrolyte membrane, wherein the in-situ curing treatment includes a first drying treatment, a second drying treatment, and an ultraviolet light treatment in sequence.

[0052] The solvent contained in the preform mixture makes the preform mixture have strong fluidity, so that the preform mixture can be evenly covered on the base film to form a layered film structure. In the in-situ curing process, the solvent is first removed through the first drying process, and the mixed state of the binder and the sulfide electrolyte in the preform mixture is retained. Furthermore, the protective group in the binder is separated through the second drying process, and the CC bond energy of the protective group tert-butyl connected to the carbon is low because it decomposes before the main body of the binder molecular chain. After the protective group is separated from the binder molecular chain, the polar group in the binder can better form strong interactions such as ionic bonds with the sulfide electrolyte. In the ultraviolet light treatment of the in-situ curing process, the cross-linking reaction between the binder and the cross-linking agent is triggered by the combination of light conditions and photoinitiators, eliminating the unstable double bonds in the binder and forming a binder network through chemical bonding and reaction with the cross-linking agent. UV treatment increases the crosslinking degree of the binder distributed within the solid electrolyte membrane, improving the structural stability and aging resistance of the resulting solid electrolyte membrane. It also allows the sulfide electrolytes anchored by the binder network to contact each other, forming ion transfer pathways. Consequently, this in-situ curing process can produce a solid electrolyte membrane with superior mechanical properties and ionic conductivity.

[0053] In some embodiments, the temperature of the first drying process is 80° C.-120° C., and the time of the first drying process is 5 hours-10 hours. This can remove the solvent in the preform mixture, facilitating the cross-linking reaction between the binder and the cross-linking agent to form a binder network structure.

[0054] As an example, the temperature of the first drying process is 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C.

[0055] In some embodiments, the second drying process is performed at a temperature of 140°C to 160°C for a time of 2 hours to 6 hours. Under these reaction conditions, the binder undergoes a chemical change, removing the tert-butyl protecting group, fully exposing the polar groups in the binder, and maintaining the chemical stability of the sulfide electrolyte during the second drying process, thereby facilitating a full reaction with the cross-linking agent and forming a strong interaction with the sulfide electrolyte.

[0056] As an example, the temperature of the second drying process is 140°C, 145°C, 150°C, 155°C, or 160°C.

[0057] In some embodiments, the UV light treatment time is 30s-50s, and the UV light treatment intensity is 40mW / cm 2 -60mW / cm2 Under the aforementioned conditions, ultraviolet light can trigger the photoinitiator in a relatively short time to start the cross-linking reaction and complete the construction of a three-dimensional network of the binder and cross-linker in the solid electrolyte membrane. As a result, a certain degree of cross-linking structure is formed in the prepared solid electrolyte membrane, which is beneficial to improving the mechanical properties of the solid electrolyte membrane and at the same time has a high efficiency of the preparation process.

[0058] As an example, the duration of the UV light treatment is 30s, 35s, 40s, 45s, and 50s.

[0059] In some embodiments, the in-situ curing process is performed in a protective atmosphere comprising at least one of nitrogen and a rare gas, thereby reducing oxidative decomposition of the sulfide electrolyte.

[0060] In some embodiments, the photoinitiator includes at least one of benzoin methyl ether, benzoin isopropyl ether, benzophenone, 4-methylbenzophenone, 1-hydroxycyclohexyl phenyl ketone, and 2,4-diethylthioxanthone. The moderate initiation rate of the aforementioned photoinitiator helps reduce the rapid local temperature rise caused by the rapid accumulation of heat from the cross-linking reaction. This can reduce the chemical decomposition or structural changes of the sulfide electrolyte caused by the high temperature of the reaction during the preparation process, reduce the impact of the film formation process on the ion channels in the sulfide electrolyte, and improve the conductivity of the prepared solid electrolyte membrane.

[0061] In some embodiments, the base film comprises at least one of glass, polytetrafluoroethylene, glass fiber, cellulose, polyimide, and epoxy resin. The base film material has excellent insulation, mechanical strength, and chemical stability, which can reduce interference with the sulfide electrolyte during the solid electrolyte preparation process. It also provides support for the preformed mixture during the preparation process, reducing membrane defects caused by structural changes, thereby facilitating the preparation of a solid electrolyte membrane with fewer defects and higher mechanical properties.

[0062] In a second aspect, this application proposes a solid electrolyte membrane prepared using the method proposed herein. As a result, this solid electrolyte membrane has higher conductivity and stability. When used in a battery structure, it helps improve the migration rate of conductive ions in the battery, maintains structural stability during charge and discharge cycles, and exhibits excellent cycling performance.

[0063] In a third aspect, this application proposes an all-solid-state battery, comprising the solid-state electrolyte membrane proposed in this application, or a solid-state electrolyte membrane prepared using the method proposed in this application. As a result, the interface stability between battery materials in this all-solid-state battery is good, and the aforementioned solid-state battery has better safety performance and longer cycle life.

[0064] In a fourth aspect of the present application, the present application proposes a vehicle, which includes the all-solid-state battery proposed in the present application.

[0065] The present invention will be described below by way of specific examples. It should be noted that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, they are determined according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments not specified by manufacturer are all commercially available conventional products.

[0066] Example 1

[0067] (1) In an inert atmosphere glove box (the glove box also contains H2O <0.1ppm, O2 <0.1ppm), 93.0g, 5.0g, 1.0g, and 1.0g of Li6PS5Cl sulfide electrolyte particles, poly[2,2-bis(trifluoromethyl)-4,4-bis(4-tert-butylphenoxy)benzidine], crosslinker diethylene glycol dimethyl ether, and photoinitiator benzophenone were weighed, added to 200.0g of xylene solvent, and stirred evenly under light-proof conditions to obtain a preformed mixture with a solid content of 50%;

[0068] (2) The preformed mixture was evenly coated on the polyimide insulating substrate using a doctor blade coater, with a wet film thickness of 200 μm and a coating speed of 10 mm / s; an in-situ curing treatment was performed, and the first drying treatment was performed in sequence: the sulfide electrolyte membrane was transferred to a vacuum oven and dried at 100 ° C for 8 h to remove the solvent; the second drying treatment was continued at 120 ° C for 4 h; and the ultraviolet light treatment was performed using a 365 nm UV-LED light source with a light intensity of 50 mW / cm 2 , irradiation time 40s, to prepare the solid electrolyte membrane.

[0069] Example 2

[0070] Example 2 is consistent with Example 1, except that the added amounts of sulfide electrolyte particles and poly[2,2'-bis(trifluoromethyl)-4,4'-bis(4-tert-butylphenoxy)benzidine] are 95.0 g and 3.0 g, respectively.

[0071] Example 3

[0072] Example 3 is consistent with Example 1, except that the added amounts of sulfide electrolyte particles and poly[2,2'-bis(trifluoromethyl)-4,4'-bis(4-tert-butylphenoxy)benzidine] are 91.0 g and 7.0 g, respectively.

[0073] Example 4

[0074] Example 4 is consistent with Example 1, except that the amount of photoinitiator added is 0.5 g.

[0075] Example 5

[0076] Example 5 is consistent with Example 1, except that the amount of photoinitiator added is 1.5 g.

[0077] Example 6

[0078] Example 6 is consistent with Example 1, except that the amount of cross-linking agent diethylene glycol dimethyl ether added is 0.5 g.

[0079] Example 7

[0080] Example 7 is consistent with Example 1, except that the amount of cross-linking agent diethylene glycol dimethyl ether added is 1.5 g.

[0081] Example 8

[0082] Example 8 is consistent with Example 1, except that the binder is poly(tert-butyl methacrylate).

[0083] Example 9

[0084] Example 9 is consistent with Example 1, except that the binder is polytert-butyl acrylate.

[0085] Example 10

[0086] Example 10 is consistent with Example 1, except that the binder is tert-butyl polycarbonate-polydimethylsiloxane block copolymer.

[0087] Comparative Example 1

[0088] Comparative Example 1 is consistent with Example 1, except that the binder is polyisobutylene.

[0089] Comparative Example 2

[0090] Comparative Example 2 is consistent with Example 1, except that no crosslinking agent and photoinitiator are added.

[0091] Comparative Example 3

[0092] Comparative Example 3 is consistent with Example 1, except that the second drying process is not performed.

[0093] Test method:

[0094] 1. Ionic conductivity test

[0095] First, scrape an appropriate amount of solid electrolyte membrane powder from the prepared solid electrolyte membrane and pour it into the solid-state battery mold, and apply a pressure of 200MPa-400MPa for tableting. Use a vernier caliper to measure the thickness of the solid electrolyte membrane and record the data. Then place aluminum foil, lithium sheet, and indium sheet as electrodes at both ends of the solid electrolyte membrane, and assemble a stainless steel kit to provide stable operating pressure. Then connect the mold battery to the electrochemical workstation, set the AC impedance test frequency range to 1Hz-1MHz, and the voltage amplitude to 10mV. Then calculate the ionic conductivity according to the formula δe=L / R·S (δe is the ionic conductivity, L is the thickness of the solid electrolyte membrane, R is the steady-state resistance, and S is the area of ​​the solid electrolyte membrane).

[0096] 2. Tensile strength test method

[0097] Cut the solid electrolyte membrane into a rectangular shape (10 mm wide and 50 mm long). Place the rectangular sample in the fixture of a universal testing machine, ensuring that the centerline of the sample aligns with the fixture to avoid stress concentration or slippage. Start the testing machine until the sample breaks, and the tensile strength is obtained.

[0098] 3. Cycle performance test

[0099] LiNi 0.8 Co 0.1 Mn 0.1 A cathode composite material is prepared by mixing O2 powder with a sulfide electrolyte and a conductive agent (e.g., conductive carbon black Super P) in a mass ratio of 70:28:2. Graphite powder, Super P, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio (e.g., 80:10:10), and an appropriate amount of N-methyl-2-pyrrolidone (NMP) is added in a high-speed blender and stirred to form a uniform slurry. The negative electrode slurry is evenly coated onto cleaned copper foil to a uniform thickness. The coated copper foil is placed in an oven and dried at 80°C-120°C for 2-4 hours. A solid-state mold battery is assembled in the following order: aluminum foil / composite positive electrode / solid-state electrolyte membrane / graphite electrode. The solid-state mold battery is cycled at a rate of 0.1C using a charge-discharge constant current cycler over a voltage range of 2.5V-4.25V (1C = 180mAh / g).

[0100] Test results: See Table 1.

[0101] Table 1

[0102] Conductivity (S / cm) Tensile strength (Mpa) Capacity retention rate after 100 cycles Example 1 <![CDATA[3.7×10 -3 ]]> 18.4 89.59％ Example 2 <![CDATA[3.2×10 -3 ]]> 16.4 87.64％ Example 3 <![CDATA[3.1×10 -3 ]]> 15.6 86.89％ Example 4 <![CDATA[2.8×10 -3 ]]> 15.4 85.12％ Example 5 <![CDATA[2.9×10 -3 ]]> 15.8 86.34％ Example 6 <![CDATA[3.0×10 -3 ]]> 15.6 85.36％ Example 7 <![CDATA[2.9×10 -3 ]]> 15.4 84.96％ Example 8 <![CDATA[3.4×10 -3 ]]> 17.3 87.87％ Example 9 <![CDATA[3.3×10 -3 ]]> 17.1 87.14％ Example 10 <![CDATA[3.1×10 -3 ]]> 17.2 87.58％ Comparative Example 1 <![CDATA[2.5×10 -3 ]]> 13.7 78.67％ Comparative Example 2 <![CDATA[2.7×10 -3 ]]> 14.9 82.64％ Comparative Example 3 <![CDATA[2.4×10 -3 ]]> 14.5 81.71％

[0103] The ionic conductivity of the prepared solid electrolyte membrane was measured by electrochemical impedance spectroscopy (EIS), as shown in Table 1. Referring to Examples 1-3, after the binder undergoes the second drying treatment, the tert-butyl functional groups in the binder are thermally decomposed, thereby exposing the bonding effect provided by the polar functional groups, and under the action of the photoinitiator, the small molecule compound and the binder are cross-linked to form a network bonding structure, which ensures the ion transmission path of the sulfide electrolyte membrane and improves its tensile strength. The amount of binder added varies within the scope of protection of this application. The prepared solid electrolyte membrane has excellent comprehensive performance, the membrane body is dense and smooth, there are fewer visible defects, the ion channels in the membrane layer are connected, the ion conductivity is high, and the tensile strength is also high.

[0104] With reference to Examples 1, 4, and 5, variations in the photoinitiator content can affect the degree of crosslinking of the binder in the solid electrolyte membrane. Within the scope of this application, a relatively uniform binder network can be formed within the prepared solid electrolyte membrane, supporting the sulfide electrolyte, which is strongly connected to it, forming ion transport channels and providing mechanical strength to the solid electrolyte membrane.

[0105] With reference to Examples 1, 6, and 7, the content of the crosslinking agent affects the crosslinking effect of the binder. Within the scope of protection of this application, the crosslinking agent reacts with the binder in the prepared solid electrolyte membrane to form a relatively uniform binder network structure, resulting in the solid electrolyte membrane having high electrical conductivity and tensile strength.

[0106] With reference to Example 1, Example 8, Example 9, and Example 10, solid electrolyte membranes with excellent ionic conductivity and mechanical properties can be prepared by using different types of binders in the method proposed in this application.

[0107] Combining the data results of Example 1 and Comparative Example 1, it can be seen that, relative to the binder having a tert-butyl protecting group, the non-polar polymer as a binder generates adhesion only by van der Waals force, and the bonding effect is poor, which is not conducive to the ion transport and mechanical properties between the sulfide electrolyte particles. Combining the data results of Example 1 and Comparative Example 2, it can be seen that when there is no photoinitiator and cross-linking agent to promote the binder to form a network bonding structure, the ionic conductivity and mechanical properties of the sulfide electrolyte membrane are poor. Combining the data results of Example 1 and Comparative Example 3, it can be seen that when the protecting group tert-butyl group is not removed by the second drying treatment, the binder cannot provide more polar sites to improve adhesion, so the ionic conductivity and mechanical properties of the sulfide electrolyte membrane are poor.

[0108] The results of the cycle test of the all-solid-state battery assembled with the solid electrolyte membrane prepared in Example 1 are shown in Figure 1It can be seen that the first-cycle capacity of the all-solid-state battery is 185.45 mAh / g. After 100 cycles at a rate of 0.1C, its capacity decays to 166.15 mAh / g, and the capacity retention rate is 89.59%, showing excellent cycle performance.

[0109] In the description of this application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for example, and may be any technical feature connected by "and / or" in this application.

[0110] In this application, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), indicating that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0111] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a solid electrolyte membrane, characterized in that: include: Dispersing and mixing a binder, a cross-linking agent, a sulfide electrolyte, a photoinitiator, and a solvent to obtain a preformed mixture, wherein the binder includes a protective group, and the protective group includes a tert-butyl group; The preformed mixture is coated on at least one side of a base film and subjected to an in-situ curing treatment to obtain the solid electrolyte membrane, wherein the in-situ curing treatment includes a first drying treatment, a second drying treatment, and an ultraviolet light treatment performed in sequence.

2. The method according to claim 1, characterized in that The binder includes at least one of a tert-butyl polycarbonate, a tert-butyl acrylate, and a tert-butyl polyimide, wherein the tert-butyl polycarbonate includes at least one of a tert-butyl polycarbonate-polydimethylsiloxane block copolymer, a tert-butyl carbonate side chain grafted polycarbonate, and poly[2,2-bis(4-hydroxy-3-tert-butylphenyl)propane]; the tert-butyl acrylate includes at least one of polytert-butyl methacrylate, polytert-butyl acrylate, polytert-butyl methacrylate grafted polystyrene, and polytert-butyl acrylate grafted polystyrene; and the tert-butyl polyimide includes at least one of poly[2,2'-bis(trifluoromethyl)-4,4'-bis(4-tert-butylphenoxy)benzidine] and poly[tert-butyl 3,5-diaminobenzoate].

3. The method according to claim 1, characterized in that In the preform mixture, the mass ratio of the binder, the sulfide electrolyte, the crosslinking agent, and the photoinitiator is (3-7): (91-95): (0.5-1.5): (0.5-1.5); and / or, The mass ratio of the binder to the solvent is 1:(10-100).

4. The method according to claim 1, wherein The cross-linking agent includes at least one of diethylene glycol dimethyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 2-nitro-2-methylpropane.

5. The method according to claim 1, wherein The temperature of the first drying treatment is 80° C.-120° C., and the time of the first drying treatment is 5 h-10 h; and / or, The temperature of the second drying process is 140° C.-160° C., and the time of the second drying process is 2 hours-6 hours; and / or, The duration of the ultraviolet light treatment is 30s-50s, and the light intensity of the ultraviolet light treatment is 40mW / cm 2 -60mW / cm 2 .

6. The method according to claim 1, characterized in that The sulfide electrolyte includes at least one of ternary sulfide and polysulfide, wherein the ternary sulfide includes Li3PS4, Li7P3S 11 At least one of the polysulfides includes Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 At least one of; and / or, The Dv50 particle size of the sulfide electrolyte is 100 nm-20 μm.

7. The method according to any one of claims 1 to 6, characterized in that The solvent includes at least one of toluene, xylene, n-hexane, n-heptane, methylcyclohexane, n-octane, ether, and tetrahydrofuran.

8. The method according to any one of claims 1 to 6, characterized in that The speed of the dispersion and mixing process is 100 rpm to 300 rpm, and the time of the dispersion and mixing process is 1 hour to 24 hours; and / or, The dispersion and mixing process is carried out in a protective atmosphere, and the protective atmosphere includes at least one of an inert gas and nitrogen.

9. The method according to any one of claims 1 to 6, characterized in that The photoinitiator includes at least one of benzoin methyl ether, benzoin isopropyl ether, benzophenone, 4-methylbenzophenone, 1-hydroxycyclohexyl phenyl ketone, and 2,4-diethylthioxanthone.

10. The method according to any one of claims 1 to 6, characterized in that The base film includes at least one of glass, polytetrafluoroethylene, glass fiber, cellulose, polyimide, and epoxy resin.

11. A solid electrolyte membrane, characterized in that: The method according to any one of claims 1 to 10 is used for preparation.

12. An all-solid-state battery, characterized in that: The invention comprises the solid electrolyte membrane according to claim 11, or a solid electrolyte membrane prepared by the method according to any one of claims 1 to 10.

13. A vehicle, characterized in that: The vehicle includes the all-solid-state battery according to claim 12.

Images