Composite solid electrolyte membrane and method for manufacturing the same

Abstract

The application belongs to the technical field of solid electrolyte preparation, and particularly relates to a composite solid electrolyte film and a preparation method thereof. The composite solid electrolyte film comprises the following raw materials in parts by weight: inorganic solid electrolyte 80-120 parts, organic electrolyte 2-10 parts, dispersing agent 0.1-0.3 parts and plasticizer 0.05-0.15 parts. The beneficial effects of the application include: the composite solid electrolyte film combines the high strength of the inorganic solid electrolyte and the high ion transmissivity of the organic electrolyte, and the synergistic effect of the plasticizer and the dispersing agent, so that the ion conductivity of the solid electrolyte film is improved, the mechanical performance is improved, and the interface compatibility is optimized, thereby enhancing the overall performance and safety of the battery.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte preparation technology, specifically relating to a composite solid electrolyte membrane and its preparation method. Background Technology

[0002] With the rapid development of portable electronic devices and electric vehicles, the demand for energy storage devices with high energy density and high safety is becoming increasingly urgent. Solid electrolytes, as a novel type of electrolyte material, have advantages such as high safety, high ionic conductivity, and a wide electrochemical window, making them a current research hotspot.

[0003] Currently, organic electrolytes suffer from low ionic conductivity, while inorganic electrolytes are brittle, have poor interfacial compatibility, and require complex preparation processes. Organic-inorganic composite solid electrolytes, however, combine the advantages of both organic and inorganic electrolytes and show promising development prospects. Nevertheless, effectively dispersing inorganic particles and improving the performance of the electrolyte membrane remain challenges during the preparation process. Summary of the Invention

[0004] This application provides a composite solid electrolyte membrane, its preparation method, and its application, aiming to solve the problems of existing solid electrolyte membranes, such as low ionic conductivity, poor solid-solid interface compatibility, lithium dendrite growth, insufficient chemical and thermal stability, high material cost and processing difficulty, difficulty in balancing overall battery performance, and safety issues.

[0005] The first aspect of this application provides a composite solid electrolyte membrane comprising the following raw materials in parts by weight: 80-120 parts of inorganic solid electrolyte, 2-10 parts of organic electrolyte, 0.1-0.3 parts of dispersant and 0.05-0.15 parts of plasticizer.

[0006] The composite solid electrolyte membrane described in this application combines the high strength of inorganic solid electrolytes with the high ion mobility of organic electrolytes, as well as the synergistic effect of plasticizers and dispersants, to achieve improved ionic conductivity, enhanced mechanical properties, and optimized interfacial compatibility of the solid electrolyte membrane, thereby enhancing the overall performance and safety of the battery.

[0007] According to some embodiments of the composite solid electrolyte membrane described in this application, the inorganic solid electrolyte includes one or more of lithium lanthanum zirconium titanium oxide, lithium lanthanum zirconium oxide, lithium phosphorus oxynitrogen, and lithium lutetium yttrium titanate.

[0008] According to some embodiments of the composite solid electrolyte membrane described in this application, the organic electrolyte includes one or more of polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylonitrile.

[0009] According to some embodiments of the composite solid electrolyte membrane described in this application, the dispersant includes one or more of surfactants, coupling agents, polyacrylonitrile, and polystyrene sulfonic acid.

[0010] According to some embodiments of the composite solid electrolyte membrane described in this application, the plasticizer includes one or more of ethyl cellulose, polyvinylidene fluoride, nanocellulose, and graphene.

[0011] According to some embodiments of the composite solid electrolyte membrane described in this application, the number-average molecular weight of the polyethylene oxide is 9 × 10⁻⁶. 4 -11×10 4 .

[0012] According to some embodiments of the composite solid electrolyte membrane described in this application, the surfactant includes polyvinylpyrrolidone.

[0013] According to some embodiments of the composite solid electrolyte membrane described in this application, the coupling agent includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0014] A second aspect of this application provides a method for preparing the composite solid electrolyte membrane described in the first aspect of this application, comprising the following steps:

[0015] (1) Mix the inorganic solid electrolyte, dispersant and solvent to obtain a mixed solution, and then ball mill the mixed solution to obtain an inorganic solid electrolyte slurry;

[0016] (2) The organic electrolyte, plasticizer and the inorganic solid electrolyte slurry are mixed to obtain an organic-inorganic composite solid electrolyte slurry;

[0017] (3) The organic-inorganic composite solid electrolyte slurry is coated on a release film, dried, and peeled off to obtain a composite solid electrolyte membrane.

[0018] The preparation method described in this application improves the dispersibility of the inorganic solid electrolyte in the organic electrolyte by adding a dispersant during ball milling, effectively reducing agglomeration and thus enhancing the ionic conductivity and mechanical properties of the electrolyte membrane. Simultaneously, the addition of the dispersant also improves the interfacial characteristics of the inorganic solid electrolyte and optimizes interfacial compatibility. The introduction of plasticizers and organic electrolytes further enhances the flexibility and ionic conductivity of the electrolyte membrane. By combining the high strength of the inorganic solid electrolyte with the high ion mobility of the organic electrolyte, this composite solid electrolyte membrane achieves improved ionic conductivity, enhanced mechanical properties, and optimized interfacial compatibility, thereby improving the overall performance and safety of the battery.

[0019] According to some embodiments of the preparation method described in this application, in step (1), the solvent includes one or more of acetonitrile, acetone, N-methylpyrrolidone and N,N-dimethylformamide.

[0020] According to some embodiments of the preparation method described in this application, the solid content in the mixed solution is 60%-80%.

[0021] According to some embodiments of the preparation method described in this application, the particle size of the inorganic solid electrolyte is 0.8-3 μm.

[0022] According to some embodiments of the preparation method described in this application, the ball milling temperature is 20-40℃, the ball milling speed is 800-1200 rpm, and the ball milling time is 2-6 hours.

[0023] According to some embodiments of the preparation method described in this application, the particle size of the solid in the inorganic solid electrolyte slurry is 0.2-0.4 μm.

[0024] According to some embodiments of the preparation method described in this application, the ball milling media used in the ball milling includes one or more of zirconia grinding balls, alumina grinding balls, silicon carbide grinding balls, and silicon nitride grinding balls.

[0025] According to some embodiments of the preparation method described in this application, the amount of the ball milling media is 1 / 4 to 1 / 5 of the mass of the inorganic solid electrolyte.

[0026] According to some embodiments of the preparation method described in this application, in step (2), the mixing temperature is 20-40℃, the mixing speed is 300-600rpm, and the mixing time is 0.5-5h.

[0027] According to some embodiments of the preparation method described in this application, the viscosity of the organic-inorganic composite solid electrolyte slurry is 200-5000 mPas.

[0028] According to some embodiments of the preparation method described in this application, the solid content of the organic-inorganic composite solid electrolyte slurry is 55%-70%.

[0029] According to some embodiments of the preparation method described in this application, in step (3), the release film is a PET release film.

[0030] According to some embodiments of the preparation method described in this application, the drying temperature is 90-100℃ and the drying time is 6-8h.

[0031] According to some embodiments of the preparation method described in this application, the thickness of the composite solid electrolyte membrane is 30-150 μm.

[0032] A third aspect of this application provides a solid-state battery, including the composite solid-state electrolyte membrane described in the first aspect of this application or the composite solid-state electrolyte membrane obtained by the preparation method described in the second aspect of this application.

[0033] According to some embodiments of the solid-state battery described in this application, the solid-state battery includes a solid-state lithium-ion battery or a solid-state lithium-sulfur battery. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure used for testing the electrochemical performance of the composite solid electrolyte membrane described in this application. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0037] This application provides a composite solid electrolyte membrane comprising the following raw materials in parts by weight: 80-120 parts of inorganic solid electrolyte, 2-10 parts of organic electrolyte, 0.1-0.3 parts of dispersant and 0.05-0.15 parts of plasticizer.

[0038] The composite solid electrolyte membrane described in this application combines the high strength of inorganic solid electrolytes with the high ion mobility of organic electrolytes, as well as the synergistic effect of plasticizers and dispersants, to achieve improved ionic conductivity, enhanced mechanical properties, and optimized interfacial compatibility of the solid electrolyte membrane, thereby enhancing the overall performance and safety of the battery.

[0039] In some embodiments of this application, the raw materials include the following parts by weight: 90-110 parts of inorganic solid electrolyte, 4-5 parts of organic electrolyte, 0.15-0.25 parts of dispersant and 0.09-0.11 parts of plasticizer.

[0040] In some embodiments of this application, the raw materials include the following parts by weight: 95-105 parts of inorganic solid electrolyte, 4-5 parts of organic electrolyte, 0.18-0.23 parts of dispersant and 0.09-0.1 parts of plasticizer.

[0041] In some embodiments of this application, the raw materials include the following parts by weight: 100 parts of inorganic solid electrolyte, 5 parts of organic electrolyte, 0.2 parts of dispersant and 0.1 parts of plasticizer.

[0042] In some embodiments of this application, the inorganic solid electrolyte includes one or more of lithium lanthanum zirconium titanate, lithium lanthanum zirconium titanate, lithium phosphorus oxynitrogen, and lithium lutetium yttrium titanate.

[0043] In some embodiments of this application, the organic electrolyte includes one or more of polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, and polyacrylonitrile;

[0044] In some embodiments of this application, the dispersant includes one or more of surfactants, coupling agents, polyacrylonitrile, and polystyrene sulfonic acid.

[0045] In some embodiments of this application, the plasticizer includes one or more of ethyl cellulose, polyvinylidene fluoride, nanocellulose, and graphene.

[0046] In some embodiments of this application, the number-average molecular weight of the polyethylene oxide is 9 × 10⁻⁶. 4 -11×10 4 This can improve the ionic conductivity of the electrolyte membrane, optimize processing performance, and ensure the uniformity and density of the membrane. Polyethylene oxides within this number-average molecular weight range exhibit high ionic conductivity. Higher molecular weights contribute to the formation of a better polymer chain network structure, thereby increasing lithium-ion mobility and enhancing the overall ionic conductivity of the electrolyte membrane. This molecular weight range also ensures that the polyethylene oxide has a moderate viscosity in solution, facilitating processing and film formation while maintaining membrane uniformity and density, and reducing defect formation.

[0047] In some embodiments of this application, the surfactant includes polyvinylpyrrolidone.

[0048] In some embodiments of this application, the coupling agent includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0049] This application also provides a method for preparing the composite solid electrolyte membrane described in the first aspect of this application, comprising the following steps:

[0050] (1) Mix the inorganic solid electrolyte, dispersant and solvent to obtain a mixed solution, and then ball mill the mixed solution to obtain an inorganic solid electrolyte slurry;

[0051] (2) The organic electrolyte, plasticizer and the inorganic solid electrolyte slurry are mixed to obtain an organic-inorganic composite solid electrolyte slurry;

[0052] (3) The organic-inorganic composite solid electrolyte slurry is coated on a release film, dried, and peeled off to obtain a composite solid electrolyte membrane.

[0053] The preparation method described in this application improves the dispersibility of the inorganic solid electrolyte in the organic electrolyte by adding a dispersant during ball milling, effectively reducing agglomeration and thus enhancing the ionic conductivity and mechanical properties of the electrolyte membrane. Simultaneously, the addition of the dispersant also improves the interfacial characteristics of the inorganic solid electrolyte and optimizes interfacial compatibility. The introduction of plasticizers and organic electrolytes further enhances the flexibility and ionic conductivity of the electrolyte membrane. By combining the high strength of the inorganic solid electrolyte with the high ion mobility of the organic electrolyte, this composite solid electrolyte membrane achieves improved ionic conductivity, enhanced mechanical properties, and optimized interfacial compatibility, thereby improving the overall performance and safety of the battery.

[0054] In some embodiments of this application, in step (1), the solvent includes one or more of acetonitrile, acetone, N-methylpyrrolidone and N,N-dimethylformamide.

[0055] In some embodiments of this application, the solid content in the mixed solution is 60%-80%, such as 60%, 65%, 68%, 70%, 76%, 80%, etc. When the media filling rate is higher than 50%, the increase in media filling will promote the impact of the ball milling media on the ball milling material, effectively shortening the ball milling time.

[0056] In some embodiments of this application, the particle size of the inorganic solid electrolyte is 0.8-3 μm, such as 0.8 μm, 1.2 μm, 1.6 μm, 2.3 μm, 2.7 μm, 3 μm, etc.

[0057] In some embodiments of this application, the ball mill temperature is 20-40℃, such as 20℃, 25℃, 28℃, 30℃, 32℃, 36℃, 40℃, etc., and the ball mill rotation speed is 800-1200rpm, such as 800rpm, 900rpm, 920rpm, 960rpm, 1000rpm, 1050rpm, 1200rpm, etc., and the ball milling time is 2-6 hours. Ball milling within the temperature range of 20-40℃ can avoid thermal damage to the material or grain growth due to excessive temperature. The rotation speed range of 800-1200rpm can provide sufficient energy to achieve effective grinding, while avoiding excessive material crushing or equipment wear caused by excessive rotation speed. The reasonable ball milling time can ensure the uniformity and fineness of the material, while maintaining production efficiency.

[0058] In some embodiments of this application, the particle size of the solid in the inorganic solid electrolyte slurry is 0.2-0.4 μm, such as 0.2 μm, 0.3 μm, 0.35 μm, 0.4 μm, etc. Solid electrolytes prepared from small-particle-size solid electrolyte powders have high purity and good dispersibility, which can effectively improve conductivity.

[0059] In some embodiments of this application, the ball milling media used include one or more of zirconia grinding balls, alumina grinding balls, silicon carbide grinding balls, and silicon nitride grinding balls.

[0060] In some embodiments of this application, the amount of the ball milling media is 1 / 4 to 1 / 5 of the mass of the inorganic solid electrolyte.

[0061] In some embodiments of this application, in step (2), the mixing temperature is 20-40℃, such as 20℃, 25℃, 30℃, 32℃, 40℃, etc., the mixing speed is 300-600rpm, such as 300rpm, 350rpm, 400rpm, 450rpm, 520rpm, 560rpm, 600rpm, etc., and the mixing time is 0.5-5h.

[0062] In some embodiments of this application, the viscosity of the organic-inorganic composite solid electrolyte slurry is 200-5000 mPas, such as 200 mPas, 500 mPas, 1000 mPas, 1600 mPas, 2100 mPas, 2700 mPas, 3300 mPas, 3800 mPas, 4300 mPas, 4900 mPas, 5000 mPas, etc. Within this viscosity range, the electrolyte slurry has good fluidity and processability.

[0063] In some embodiments of this application, the solid content of the organic-inorganic composite solid electrolyte slurry is 55%-70%, such as 55%, 60%, 68%, 70%, etc.

[0064] In some embodiments of this application, in step (3), the release film is a PET release film.

[0065] In some embodiments of this application, the drying temperature is 90-100℃, such as 90℃, 95℃, 98℃, 100℃, etc., and the drying time is 6-8h.

[0066] In some embodiments of this application, the thickness of the composite solid electrolyte membrane is 30-150 μm, such as 30 μm, 50 μm, 80 μm, 120 μm, 136 μm, 150 μm, etc.

[0067] This application also provides a solid-state battery, including the composite solid-state electrolyte membrane described in the first aspect of this application or the composite solid-state electrolyte membrane obtained by the preparation method described in the second aspect of this application.

[0068] In some embodiments of this application, the solid-state battery includes a solid-state lithium-ion battery or a solid-state lithium-sulfur battery.

[0069] The technical solution of this application will be further described below with reference to specific embodiments and accompanying drawings.

[0070] Example 1

[0071] A method for preparing a composite solid electrolyte membrane includes the following steps:

[0072] Step 1: Preparation of inorganic solid electrolyte slurry

[0073] An inorganic solid electrolyte, lithium lanthanum zirconium titanium oxide (LLZTO), with a particle size of 0.8 μm, was added to an acetonitrile (ACN) solution containing polyacrylonitrile (PAN) as a dispersant, resulting in a solid content of 70% in the mixed solution. The amount of polyacrylonitrile (PAN) in the solution was 0.2% of the mass of the inorganic solid electrolyte. The LLZTO solid electrolyte was ball-milled using a high-speed dispersing ball mill with zirconium oxide grinding balls as the milling media. The amount of milling media was 1 / 4 of the mass of the inorganic solid electrolyte. The ball milling speed was controlled at 1000 rpm, the ball milling temperature was controlled at 35℃, and the ball milling dispersion time was 4 h, resulting in an inorganic solid electrolyte slurry with a particle size of 0.2-0.4 μm.

[0074] Step 2: Preparation of organic-inorganic composite solid electrolyte slurry

[0075] The organic electrolyte polyethylene oxide (PEO) (number average molecular weight approximately 100,000) and the above-mentioned inorganic solid electrolyte slurry were stirred and mixed at 30°C and 450 rpm for 4 hours to fully dissolve the organic electrolyte. The amount of organic electrolyte polyethylene oxide added was 5% of the mass of the inorganic solid electrolyte. After the organic electrolyte was fully dissolved, the plasticizer ethyl cellulose was added and mixed evenly. The amount of plasticizer added was 0.1% of the mass of the inorganic solid electrolyte, resulting in an organic-inorganic composite solid electrolyte slurry. Acetonitrile solution was added to adjust the solid content of the composite solid electrolyte slurry to 65% and the viscosity to 500 mPas.

[0076] Step 3: Preparation of organic-inorganic composite solid electrolyte membrane

[0077] Using PET release film as foil, the organic-inorganic composite solid electrolyte slurry described in step 2 is coated onto the smooth surface of the PET release film using an extrusion coating machine. The film is then baked at 95°C for 6 hours to obtain a composite solid electrolyte electrode sheet. The composite solid electrolyte electrode sheet is then peeled off using a stacking and peeling device to obtain an organic-inorganic composite solid electrolyte membrane with a thickness of 80 μm.

[0078] Example 2

[0079] The only difference between the preparation method of the composite solid electrolyte membrane in Example 2 and that in Example 1 is the amount of organic electrolyte added. The amount of the organic electrolyte, polyethylene oxide, added is 2% of the mass of the inorganic solid electrolyte.

[0080] Example 3

[0081] The only difference between the preparation method of the composite solid electrolyte membrane in Example 3 and that in Example 1 is the amount of organic electrolyte added. The amount of the organic electrolyte, polyethylene oxide, added is 10% of the mass of the inorganic solid electrolyte.

[0082] Example 4

[0083] The only difference between the preparation method of the composite solid electrolyte membrane in Example 4 and that in Example 1 is the amount of plasticizer added. The amount of plasticizer added is 0.5% of the mass of the inorganic solid electrolyte.

[0084] Example 5

[0085] The only difference between the preparation method of the composite solid electrolyte membrane described in Example 5 and that in Example 1 is the amount of plasticizer added. The amount of plasticizer added is 1.5% of the mass of the inorganic solid electrolyte.

[0086] Example 6

[0087] The only difference between the preparation method of the composite solid electrolyte membrane in Example 6 and that in Example 1 is the ball milling time. The ball milling dispersion time is 2 hours, resulting in an inorganic solid electrolyte slurry.

[0088] Example 7

[0089] The only difference between the preparation method of the composite solid electrolyte membrane in Example 7 and that in Example 1 is the milling time. The ball milling dispersion time is 6 hours, resulting in an inorganic solid electrolyte slurry.

[0090] Comparative Example 1

[0091] The only difference between the preparation method of the composite solid electrolyte membrane in Comparative Example 1 and Example 1 is that the inorganic solid electrolyte and the organic electrolyte are mixed and ball-milled. Specifically, the composite solid electrolyte membrane in Comparative Example 1 is prepared by adding the inorganic solid electrolyte and the organic electrolyte together to an acetonitrile solution containing the dispersant polyacrylonitrile, and then ball-milling them.

[0092] The specific steps are as follows:

[0093] Step 1: Preparation of inorganic solid electrolyte slurry

[0094] An inorganic solid electrolyte, lithium lanthanum zirconium titanium oxide (LLZTO), with a particle size of 0.3 μm, and an organic electrolyte, polyethylene oxide (PEO) (number-average molecular weight approximately 100,000), were added to an acetonitrile (ACN) solution containing polyacrylonitrile (PAN) as a dispersant, resulting in a solid content of 70% in the mixed solution. The amount of PAN in the solution was 0.2% of the inorganic solid electrolyte mass, and the amount of PEO was 5% of the inorganic solid electrolyte mass. The LLZTO solid electrolyte was ball-milled using a high-speed dispersing ball mill with zirconium oxide grinding balls as the milling media. The amount of milling media was 1 / 4 of the inorganic solid electrolyte mass. The ball milling speed was controlled at 1000 rpm, the ball milling temperature at 35℃, and the ball milling dispersion time at 4 h, resulting in an organic-inorganic solid electrolyte slurry with a particle size of 0.2-0.4 μm.

[0095] The plasticizer ethyl cellulose was added to the above organic-inorganic solid electrolyte slurry and mixed evenly. The amount of plasticizer added was 0.1% of the mass of the inorganic solid electrolyte, resulting in a composite solid electrolyte slurry. Acetonitrile solution was added to adjust the solid content of the composite solid electrolyte slurry to 65% and the viscosity to 500 mPas.

[0096] Step 2: Preparation of organic-inorganic composite solid electrolyte membrane

[0097] Using PET release film as foil, the organic-inorganic composite solid electrolyte slurry described in step 2 is coated onto the smooth surface of the PET release film using an extrusion coating machine. The film is then baked at 95°C for 6 hours to obtain a composite solid electrolyte electrode sheet. The composite solid electrolyte electrode sheet is then peeled off using a stacking and peeling device to obtain an organic-inorganic composite solid electrolyte membrane with a thickness of 80 μm.

[0098] Comparative Example 2

[0099] The only difference between the preparation method of the composite solid electrolyte membrane described in Comparative Example 2 and Example 1 is that the inorganic solid electrolyte is not subjected to ball milling, but rather the inorganic solid electrolyte, organic electrolyte, dispersant and plasticizer are mixed evenly to obtain an organic-inorganic composite solid electrolyte slurry.

[0100] The specific steps are as follows:

[0101] Step 1: Preparation of inorganic solid electrolyte slurry

[0102] An inorganic solid electrolyte, lithium lanthanum zirconium titanium oxide (LLZTO), with a particle size of 0.3 μm, and an organic electrolyte, polyethylene oxide (PEO) (number average molecular weight approximately 100,000), were added to an acetonitrile (ACN) solution containing polyacrylonitrile (PAN) as a dispersant, so that the solid content in the mixed solution was 70%. The amount of polyacrylonitrile (PAN) in the solution was 0.2% of the mass of the inorganic solid electrolyte, and the amount of polyethylene oxide added was 5% of the mass of the inorganic solid electrolyte, resulting in an organic-inorganic solid electrolyte slurry with a particle size of 0.2-0.4 μm.

[0103] The plasticizer ethyl cellulose was added to the above organic-inorganic solid electrolyte slurry and mixed evenly. The amount of plasticizer added was 0.1% of the mass of the inorganic solid electrolyte, resulting in an organic-inorganic composite solid electrolyte slurry. Acetonitrile solution was added to adjust the solid content of the composite solid electrolyte slurry to 65% and the viscosity to 500 mPas.

[0104] Step 2: Preparation of organic-inorganic composite solid electrolyte membrane

[0105] Using PET release film as foil, the organic-inorganic composite solid electrolyte slurry described in step 2 is coated onto the smooth surface of the PET release film using an extrusion coating machine. The film is then baked at 95°C for 6 hours to obtain a composite solid electrolyte electrode sheet. The composite solid electrolyte electrode sheet is then peeled off using a stacking and peeling device to obtain an organic-inorganic composite solid electrolyte membrane with a thickness of 80 μm.

[0106] The physical properties of the composite solid electrolyte membranes described in Examples 1-7 and Comparative Examples 1-2 of this application were studied, and the results are shown in Table 1:

[0107] Table 1

[0108]

[0109]

[0110] Note: 72h viscosity (mPas) refers to the viscosity change of a material over 72 hours, and is usually used to measure the stability and flow properties of a material.

[0111] The viscosity test method described in this application is performed using a rotational viscometer. According to GB / T 2793.1-1995 "Determination of viscosity of adhesives – Part 1: Rotational viscometer method", the sample is placed in the measuring container of the viscometer, and the viscosity value of the sample is calculated by measuring the rotational speed of the container and the resulting torque.

[0112] 72h particle size (µm) refers to the change in particle size of a material over 72 hours, and is commonly used to assess the particle size stability of a material. Particle size refers to the size of a particle, measured in micrometers (µm).

[0113] The particle size test in this application adopts laser diffraction measurement technology, according to GB / T 19077-2003 "Laser diffraction method for particle size analysis". During the test, the sample is introduced into the laser beam. After the laser is scattered by the particles, the scattered light signal is received by the detector, and then the particle size distribution is calculated.

[0114] Tensile strength (MPa) refers to the stress at which a material undergoes maximum uniform plastic deformation. In a tensile test, the maximum tensile stress that the specimen experiences until it breaks is the tensile strength, and the result is expressed in MPa.

[0115] The tensile strength test of this application was conducted in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Films and sheets". During the test, the specimen was made into a standard shape and stretched to break using a universal testing machine. The maximum tensile force and gauge length change were recorded, and the tensile strength and elongation at break were calculated.

[0116] As shown in Table 1, Examples 1-7 exhibit smaller viscosity and particle size variations compared to Comparative Examples 1-2, which is beneficial for improving battery charge / discharge efficiency, conductivity, cycle stability, and safety, thus contributing to enhanced battery performance. Furthermore, the higher tensile strength of Examples 1-7 indicates that the composite electrolyte membrane is less prone to breakage under tensile forces. For electrolyte membranes, higher tensile strength contributes to improved battery safety and stability.

[0117] Electrochemical performance study of the composite solid electrolyte membranes described in Examples 1-7 and Comparative Examples 1-2 of this application

[0118] Test method: Assemble a symmetrical cell with a stainless steel (SS) / solid film / stainless steel (SS) sandwich structure. Use an electrochemical workstation to test the AC impedance of the solid film within a certain temperature range. The test frequency is 10 Hz. 5 -0.1Hz, amplitude 10mV. The material resistance R is obtained by AC impedance spectroscopy (EIS) analysis, and then the ionic conductivity σ is calculated by the formula: σ=L / RS, where L is the thickness of the electrolyte membrane and S is the area of ​​the electrolyte membrane;

[0119] A solid-state half-cell was assembled with a composite solid-state electrolyte membrane, a LiFePO4 positive electrode, and a metallic Li negative electrode. The battery assembly was performed in an inert atmosphere glove box, including the assembly of a metallic lithium sheet, a negative electrode shell, an electrolyte membrane, a positive electrode sheet, and a positive electrode shell. The negative electrode shell was placed flat on an insulating platform, and the metallic lithium sheet was placed in the center of the negative electrode shell and flattened using a pressing mold. The electrolyte membrane, cut into circular pieces... Figure 1 The positive electrode and gasket are then assembled onto the lithium sheet, and the assembled button cell is placed with the negative electrode facing upwards onto the button cell sealing mold for sealing. The assembled button cell is then subjected to 0.1C constant current cycling at room temperature (25°C) to measure the initial discharge specific capacity. After a certain number of cycles, the discharge capacity retention rate is tested to evaluate the cycle stability of the battery.

[0120] The test results are shown in Table 2:

[0121] Table 2

[0122] Conductivity S / cm Capacity retention after 200 cycles Example 1 <![CDATA[9.42×10 -4 ]]> 98.59％ Example 2 <![CDATA[9.05×10 -4 ]]> 98.18％ Example 3 <![CDATA[8.90×10 -4 ]]> 98.05％ Example 4 <![CDATA[9.27×10 -4 ]]> 98.35％ Example 5 <![CDATA[9.30×10 -4 ]]> 98.27％ Example 6 <![CDATA[8.45×10 -4 ]]> 98.02％ Example 7 <![CDATA[9.36×10 -4 ]]> 98.42％ Comparative Example 1 <![CDATA[6.27×10 -4 ]]> 93.45％ Comparative Example 2 <![CDATA[3.55×10 -4 ]]> 91.67％

[0123] As can be seen from Table 2, the composite electrolyte membranes of Examples 1-7 of this invention exhibit high ionic conductivity, indicating that ions and electrons can move rapidly within the battery, achieving faster charging and discharging rates. Regarding electrochemical stability, after 200 charge-discharge cycles, the capacity retention rate of the composite electrolyte membrane used in Example 1 remained at a high level of 98.59%, demonstrating excellent electrochemical stability.

[0124] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A composite solid electrolyte membrane, characterized in that, The raw materials include the following parts by weight: 80-120 parts of inorganic solid electrolyte, 2-10 parts of organic electrolyte, 0.1-0.3 parts of dispersant and 0.05-0.15 parts of plasticizer; The inorganic solid electrolyte is lithium lanthanum zirconium titanium oxide; The organic electrolyte is polyethylene oxide; The amount of organic electrolyte added is 2% or 5% of the mass of the inorganic solid electrolyte.

2. The composite solid electrolyte membrane according to claim 1, characterized in that, The dispersant includes one or more of surfactants, coupling agents, polyacrylonitrile, and polystyrene sulfonic acid; And / or, the plasticizer includes one or more of ethyl cellulose, polyvinylidene fluoride, nanocellulose, and graphene.

3. The composite solid electrolyte membrane according to claim 2, characterized in that, The number-average molecular weight of the polyethylene oxide is 9 × 10⁻⁶. 4 -11×10 4 ; And / or, the surfactant includes polyvinylpyrrolidone; And / or, the coupling agent comprises γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

4. The method for preparing the composite solid electrolyte membrane according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Mix the inorganic solid electrolyte, dispersant and solvent to obtain a mixed solution, and ball mill the mixed solution to obtain an inorganic solid electrolyte slurry; (2) The organic electrolyte, plasticizer and the inorganic solid electrolyte slurry are mixed to obtain an organic-inorganic composite solid electrolyte slurry; (3) The organic-inorganic composite solid electrolyte slurry is coated on a release film, dried, and peeled off to obtain a composite solid electrolyte membrane.

5. The method for preparing the composite solid electrolyte membrane according to claim 4, characterized in that, In step (1), the solvent includes one or more of acetonitrile, acetone, N-methylpyrrolidone, and N,N-dimethylformamide; And / or, the solid content in the mixed solution is 60%-80%; And / or, the particle size of the inorganic solid electrolyte is 0.8-3 μm; And / or, the ball mill temperature is 20-40℃, the ball mill rotation speed is 800-1200rpm, and the ball milling time is 2-6h; And / or, the particle size of the solids in the inorganic solid electrolyte slurry is 0.2-0.4 μm.

6. The method for preparing the composite solid electrolyte membrane according to claim 5, characterized in that, The ball milling media used include one or more of the following: zirconium oxide grinding balls, alumina grinding balls, silicon carbide grinding balls, and silicon nitride grinding balls. And / or, the amount of the ball milling media is 1 / 4 to 1 / 5 of the mass of the inorganic solid electrolyte.

7. The method for preparing the composite solid electrolyte membrane according to claim 4, characterized in that, In step (2), the mixing temperature is 20-40℃, the mixing speed is 300-600rpm, and the mixing time is 0.5-5h; And / or, the viscosity of the organic-inorganic composite solid electrolyte slurry is 200-5000 mPas; And / or, the solid content of the organic-inorganic composite solid electrolyte slurry is 55%-70%.

8. The method for preparing the composite solid electrolyte membrane according to claim 4, characterized in that, In step (3), the release film is a PET release film; And / or, the drying temperature is 90-100℃, and the drying time is 6-8h.

9. The method for preparing the composite solid electrolyte membrane according to claim 4, characterized in that, The thickness of the composite solid electrolyte membrane is 30-150 μm.

10. A solid-state battery, characterized in that, This includes the composite solid electrolyte membrane according to any one of claims 1-3 or the composite solid electrolyte membrane obtained by the preparation method according to any one of claims 4-9.

11. The solid-state battery according to claim 10, characterized in that, The solid-state battery includes a solid-state lithium-ion battery or a solid-state lithium-sulfur battery.

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