An interfacial chemically bonded enhanced intercalated skeleton sulfide solid electrolyte membrane and a method of preparing the same

Abstract

This invention discloses an interfacial chemically bonded reinforced embedded framework sulfide solid electrolyte membrane and its preparation method. A slurry is prepared by mixing sulfide electrolyte, binder, and organic solvent. After coating or rolling, the slurry is partially dried until the solvent residue is 5-30 wt%, resulting in a ductile wet electrolyte membrane. The framework is then surface-functionalized, and the porous framework is pressed into the wet electrolyte membrane, with the embedding depth controlled to be 20-90% of the membrane thickness. After complete drying, the membrane is hot-pressed for densification, yielding the embedded framework sulfide solid electrolyte membrane. The resulting membrane exhibits a tensile strength of 5-15 MPa, an ionic conductivity retention rate of 85-95%, and a critical current density >2.5 mA / cm². 2 This invention solves the technical problems of low mechanical strength and poor ultra-thin processability of sulfide electrolyte membranes. The process is compatible with existing wet coating production lines and is suitable for the field of high energy density all-solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state battery technology, specifically relating to an interfacial chemical bonding enhanced embedded framework sulfide solid electrolyte membrane and its preparation method. Background Technology

[0002] While there is an urgent need for improved energy density and safety in lithium-ion batteries (LIBs), a trade-off exists between these two aspects. All-solid-state batteries (ASSBs) have been extensively studied due to their potential to overcome the design limitations of traditional flammable liquid electrolyte batteries. However, several technical challenges remain to be overcome in ASSB battery design. The solid electrolyte (SE) layer, primarily in particulate form, is significantly thicker and heavier than traditional separators in lithium-ion batteries. Due to the high cost and low production efficiency of processes such as high-pressure pressing or sintering, particulate SE layers cannot be applied to current production processes. Therefore, recent research has focused on improving ASSB performance using sheet-like SE materials. Reducing the thickness of the independent SE film to the level of LIB separators is crucial for the commercialization of ASSBs. The development of independent SE films has moved beyond initial methods such as hot pressing and dry processing, leading to the development of more advanced polymer hybrid SE materials and scaffold-supported SE film structures. However, the introduction of polymer binders significantly reduces the ionic conductivity of the film. Using a mesh scaffold as the support material for the SE film offers advantages such as high efficiency and ease of thickness control. However, these scaffolds require specialized fabrication processes such as electrospinning, which limits large-scale film production. Furthermore, the poor mechanical strength of mesh scaffolds is another bottleneck in the traditional roll-to-roll continuous fabrication process of lithium-ion batteries. Therefore, thin, highly ionicly conductive, and mechanically strong SE films have become key components of advanced ASSBs.

[0003] Current research on fiber-reinforced membranes focuses on a process where the reinforcing fibers are fixed together with the substrate during wet coating, and a doctor blade is used to coat the membrane. This method faces challenges such as uneven electrolyte membrane surfaces and the fiber reinforcement being easily carried away or torn by the doctor blade. Another approach involves incorporating the fiber reinforcement into the initial electrolyte powder-binder slurry before wet coating, but this method suffers from uneven fiber reinforcement distribution and significant differences in membrane ionic conductivity. Furthermore, the compatibility between the electrolyte membrane and its reinforcement is low, leading to easy peeling and interfacial instability. Therefore, we designed an interfacial chemically bonded embedded sulfide solid electrolyte membrane and its preparation method. Summary of the Invention

[0004] This invention aims to solve the technical problems of low mechanical strength, poor ultrathin processability, and difficulty in achieving both ionic conductivity and mechanical strength in existing sulfide electrolyte membranes. It provides an embedded framework sulfide solid electrolyte membrane with enhanced interfacial chemical bonding. By introducing functional groups that can chemically react with sulfide electrolytes or binders on the surface of the framework to form covalent bonds, lithium bonds, or coordination bonds, the interfacial bonding strength and ion transport efficiency are significantly improved.

[0005] Specifically, the porous framework undergoes surface functionalization modification before embedding, for example, by introducing active sites through plasma treatment and then grafting amino or thiol groups with a silane coupling agent; or by introducing lithium-oxygen bonds (Li-O-) through lithium salt grafting. After embedding into a wet electrolyte membrane, the modified framework forms a chemically bonded interface with the binder or sulfide electrolyte, preventing interface delamination and simultaneously constructing continuous lithium-ion transport channels.

[0006] In addition, the present invention can also add a small amount of lithium salt (such as LiTFSI, LiFSI) or crosslinking agent (such as isocyanate, epoxy resin) to the wet electrolyte membrane to initiate an interfacial crosslinking reaction during hot pressing, thereby further enhancing the interfacial stability.

[0007] To achieve the above objectives, this invention proposes a method for preparing an interfacial chemically bonded embedded framework sulfide solid electrolyte membrane, comprising the following steps: (1) Mix the sulfide electrolyte, binder and organic solvent to prepare a slurry, coat or roll it onto the substrate, and partially dry it until the solvent residue is 5-30 wt% to obtain a plastic wet electrolyte membrane; (2) The porous framework is surface functionalized and then pressed into the wet electrolyte membrane obtained in step (1), with the embedding depth controlled to be 20-90% of the thickness of the wet electrolyte membrane; (3) The electrolyte membrane with embedded skeleton obtained in step (2) is completely dried and then hot-pressed to densify it, so as to obtain an embedded skeleton sulfide solid electrolyte membrane.

[0008] All steps (1)-(3) are performed in a protective gas atmosphere.

[0009] Preferably, in step (1), the sulfide electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12The electrolyte contains at least one of Li3PS4, and the binder includes at least one of styrene-butadiene rubber (SBR), polyisobutylene (PIB), polyvinyl acetate (PVAC), hydrogenated nitrile butadiene rubber (HNBR), and polyvinylidene fluoride (PVDF). The binder accounts for 1-10 wt% of the total mass of the electrolyte, and the organic solvent includes at least one of xylene, toluene, cyclohexane, acetonitrile, tetrahydrofuran, butyl butyrate, n-hexane, and n-heptane.

[0010] Preferably, in step (1), the solid content of the slurry is 20-80 wt%, and the temperature of the partial drying is 20-60℃.

[0011] Preferably, in step (2), the porous skeleton includes at least one of polymer fiber mesh, metal mesh, nonwoven fabric, and porous ceramic membrane; the pore size of the porous skeleton is 1-100 μm, the porosity is 30-90%, and the thickness is 5-50 μm. The polymer fiber web is made of at least one of polyimide (PI), polyethylene terephthalate (PET), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyether ether ketone (PEEK), and polyphenylene sulfide (PPS). The metal mesh is made of at least one of stainless steel, nickel, copper, and aluminum, and has an insulating coating on its surface. The material of the nonwoven fabric is selected from at least one of cellulose, polypropylene (PP), and polyethylene (PE); The surface functionalization modification involves introducing functional groups that can form covalent, coordinate, or lithium bonds with sulfide electrolytes or binders. The functional groups include at least one of amino, mercapto, carboxyl, hydroxyl, sulfonic acid, silanol, lithium oxy group (Li-O-), and lithium sulfide group (Li-S-). The modification methods include one or more of plasma treatment, silane coupling agent grafting, or lithium salt grafting.

[0012] Preferably, in step (2), the pressing method is selected from at least one of roller pressing, flat plate pressing, and vacuum adsorption. The pressing pressure is 0.1-10 MPa, and the pressing temperature is 20-80℃. The pressing temperature is adjusted so that the electrolyte and the skeleton material form in-situ interface bonds and interactions.

[0013] Preferably, in step (2), the skeleton is pressed into the wet electrolyte membrane in stages by controlling the pressing pressure and time, so that the skeleton is distributed in a gradient in the direction of membrane thickness: the skeleton density is high on the surface of the membrane and the skeleton density is low inside the membrane.

[0014] Preferably, in step (3), the temperature for complete drying is 60-120℃ and the time is 2-12 hours; the temperature for hot pressing densification is 50-100℃, the pressure is 10-50 MPa, and the film thickness after hot pressing is 10-50 μm.

[0015] The present invention also proposes an interfacial chemical bonding enhanced embedded framework sulfide solid electrolyte membrane, prepared by any of the methods described above, comprising a sulfide electrolyte membrane and a porous framework embedded therein.

[0016] Preferably, the porous framework is gradient-distributed in the membrane thickness direction, with the surface framework density being higher than the internal framework density.

[0017] Preferably, the sulfide solid electrolyte membrane has a thickness of 10-50 μm, a tensile strength ≥5 MPa, and an ionic conductivity ≥2.0 mS / cm.

[0018] The present invention also proposes an all-solid-state battery comprising an interfacial chemically bonded embedded framework sulfide solid electrolyte membrane as described in any of the preceding claims.

[0019] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: (1) Significantly improved mechanical strength: The embedded skeleton forms a continuous reinforcing network inside the membrane, and the tensile strength of the membrane can reach 5-15 MPa, which is 10-30 times higher than that of pure sulfide membrane (<0.5 MPa); the puncture resistance is >200 N / mm, which effectively inhibits lithium dendrite penetration.

[0020] (2) Strong interface bonding: When the skeleton is embedded in the wet electrolyte membrane, the binder and solvent have not been fully cured. During the embedding process, the electrolyte slurry can penetrate into the skeleton pores, and the skeleton forms a chemical bond interface with the binder or sulfide electrolyte. After curing, it forms an "anchored" structure with strong interface bonding and no risk of peeling.

[0021] (3) Strong structural designability: By adjusting the embedding depth, skeleton material and number of skeleton layers, a variety of reinforcement structures (surface reinforcement, through reinforcement, multi-layer composite) can be realized to meet the different requirements of mechanical strength and ionic conductivity of different battery systems.

[0022] (4) Good process compatibility: It is compatible with existing wet coating processes. Only the "skeleton embedding" step needs to be added during the coating drying process. No additional complex equipment is required, making it easy to industrialize. Attached Figure Description

[0023] Figure 1 A cross-sectional SEM image of the electrolyte membrane prepared in Example 1; Figure 2The impedance diagram of the electrolyte membrane prepared in Example 1 shows that its ionic conductivity is calculated to be 2.4 mS / cm. Figure 3 This is a schematic diagram of a method for preparing an interfacial chemically bonded embedded framework sulfide solid electrolyte membrane according to the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.

[0025] Example 1 (1) Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g) and xylene solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 40°C for 5 minutes, controlling the residual solvent content to be about 15 wt%, to obtain a plastic wet electrolyte membrane.

[0026] (2) A polyimide (PI) electrospun fiber web (15 μm thick, 20 μm pore size, 70% porosity) was placed in an oxygen plasma treatment device at 100 W for 3 minutes to introduce hydroxyl functional groups onto the surface. It was then immersed in a 0.1 mol / L lithium ethanol solution and reacted at 60 °C for 4 hours to form a lithium-oxygen bond (Li-O-) graft layer. The PI fiber web was placed on the surface of a wet electrolyte membrane and rolled and embedded at 50 °C and 1 MPa pressure, controlling the embedding depth to be 50% of the wet membrane thickness (approximately 40 μm), thus embedding the fiber web into the surface region of the membrane.

[0027] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0028] Example 2: (1) Li6PS5Cl (LPSC) powder (10 g), PIB binder (0.3 g) and cyclohexane solvent were mixed to form a uniform slurry with a solid content of 35 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 70 μm and partially dried at 40°C for 7 minutes, controlling the residual solvent content to be about 12 wt%, to obtain a plastic wet electrolyte membrane.

[0029] (2) After plasma treatment, PET electrospun fiber web (thickness 10 μm, pore size 15 μm, porosity 65%) was grafted with KH550 silane coupling agent to introduce amino functional groups. The modified PET fiber web was placed on the surface of the wet electrolyte membrane and rolled and embedded at 60℃ and 0.8 MPa pressure, controlling the embedding depth to 90% of the wet membrane thickness (about 63 μm), so that the fiber web penetrates the membrane thickness direction to form a double-sided reinforced structure.

[0030] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 20 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0031] Example 3: (1) Li6PS5Cl (LPSC) powder (10 g), HNBR binder (0.5 g) and butyl butyrate solvent were mixed to form a uniform slurry with a solid content of 45 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 100 μm and partially dried at 50°C for 5 minutes, controlling the residual solvent content to be about 12 wt%, to obtain a plastic wet electrolyte membrane.

[0032] (2) After coating the surface of the stainless steel mesh (thickness 20 μm, pore size 50 μm, porosity 60%) with a PIB insulating layer, it is subjected to plasma treatment and grafted with thiol functional groups to enhance its chemical affinity with the electrolyte. The modified stainless steel mesh is then embedded into the wet electrolyte membrane in sequence: it is rolled and embedded at 50°C and 1 MPa pressure, and the embedding depth is controlled to be 50% of the thickness of the wet membrane (about 40 μm), so that the fiber mesh is embedded in the surface area of ​​the membrane.

[0033] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 30 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0034] Example 4 (1) PAN nonwoven fabric (thickness 20 μm, pore size 30 μm, porosity 80%) was placed in a plasma treatment device under an oxygen atmosphere and a power of 150 W for 5 minutes to introduce hydroxyl and carboxyl functional groups onto the surface. Then it was immersed in an ethanol solution containing 3-aminopropyltriethoxysilane (KH550) and reacted at 60°C for 4 hours to graft amino functional groups.

[0035] (2) Li6PS5Cl (LPSC) powder (10 g), PVAC binder (0.5 g) and acetonitrile solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 30°C for 10 minutes, controlling the residual solvent content to be about 20 wt%, to obtain a plastic wet electrolyte membrane.

[0036] (3) The modified PAN nonwoven fabric was embedded into the wet electrolyte membrane at a depth of 56 μm (70% of the membrane thickness) under the following conditions: 40℃ and 0.5 MPa.

[0037] (4) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0038] Example 5 (1) Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g) and xylene solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 40°C for 5 minutes, controlling the residual solvent content to be about 15 wt%, to obtain a plastic wet electrolyte membrane.

[0039] (2) Polyimide (PI) electrospun fiber web (15 μm thickness, 20 μm pore size, 70% porosity) was placed in an oxygen plasma treatment device at 100 W for 3 minutes to introduce hydroxyl functional groups onto the surface. It was then immersed in a 0.1 mol / L lithium ethanol solution and reacted at 60 °C for 4 hours to form a lithium-oxygen bond (Li-O-) graft layer. The two modified PI fiber webs were sequentially embedded into a wet electrolyte membrane. The first modified PI fiber web was embedded into the wet electrolyte membrane at a depth controlled to 20% of the wet membrane thickness (approximately 16 μm). The second modified PI fiber web was then embedded into the wet electrolyte membrane at a depth controlled to 80% of the wet membrane thickness (64 μm), forming a multilayer composite reinforced structure. Embedding conditions: temperature 50 °C, pressure 1 MPa.

[0040] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0041] Example 6 (1) Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g) and xylene solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 40°C for 5 minutes, controlling the residual solvent content to be about 15 wt%, to obtain a plastic wet electrolyte membrane.

[0042] (2) A polyimide (PI) electrospun fiber web (15 μm thick, 20 μm pore size, 70% porosity) was placed in an oxygen plasma treatment device at 100 W for 3 minutes to introduce hydroxyl functional groups onto the surface. It was then immersed in a 0.1 mol / L lithium ethanol solution and reacted at 60 °C for 4 hours to form a lithium-oxygen bond (Li-O-) graft layer. The modified PI fiber web was then embedded into a wet electrolyte membrane, with the embedding depth controlled to be 20% of the wet membrane thickness (approximately 16 μm). Embedding conditions: temperature 50 °C, pressure 1 MPa.

[0043] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0044] Example 7 (1) Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g) and xylene solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 40°C for 5 minutes, controlling the residual solvent content to be about 15 wt%, to obtain a plastic wet electrolyte membrane.

[0045] (2) A polyimide (PI) electrospun fiber web (15 μm thick, 20 μm pore size, 70% porosity) was placed in an oxygen plasma treatment device at 100 W for 3 minutes to introduce hydroxyl functional groups onto the surface. It was then immersed in a 0.1 mol / L lithium ethanol solution and reacted at 60 °C for 4 hours to form a lithium-oxygen bond (Li-O-) graft layer. The modified PI fiber web was then embedded into a wet electrolyte membrane, with the embedding depth controlled to be 80% of the wet membrane thickness (64 μm). Embedding conditions: temperature 50 °C, pressure 1 MPa.

[0046] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0047] Example 8 Using the formulation and process of Example 1 (LPSC+SBR+PI fiber web), five groups of samples with embedding depths of 20%, 40%, 60%, 80%, and 100% (film thickness percentage) were prepared by adjusting the roller pressure (0.3-2.0MPa) and the pressing temperature (40-80℃), with three parallel samples in each group.

[0048] Table 1. Preparation parameter design table for five groups of samples in Example 8 Table 2 Performance test results of five groups of samples in Example 8 Comparative Example 1 Pure LPSC electrolyte membrane: Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g), and xylene solvent were mixed to form a homogeneous slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film to a thickness of 80 μm and partially dried at 80°C for 8 hours. After demolding, the film was cold-pressed (25°C, 300 MPa) to prepare a membrane with a thickness of 25 μm.

[0049] Comparative Example 2 PI fiber web (5 wt%) was dry-mixed with LPSC powder. 10 g of this mixture, along with 0.3 g of SBR binder and xylene solvent, was mixed to a solid content of 40 wt% and stirred for 12 hours to form a homogeneous slurry. The slurry was coated onto a PET release film to a thickness of 80 μm and partially dried at 80°C for 8 hours. After demolding, the film was cold-pressed (25°C, 300 MPa) to prepare a 25 μm thick film with the fiber web randomly distributed within it.

[0050] Comparative Example 3 A mixture of 10 g LPSC, 0.3 g SBR binder, and xylene solvent was mixed to a solid content of 40 wt% and stirred for 12 hours to form a homogeneous slurry. The slurry was then coated onto the surface of a PI fiber mesh to a thickness of 80 μm and partially dried at 80°C for 8 hours. After drying, the slurry was hot-pressed into a film, with the skeleton located in the central layer of the film.

[0051] Comparative Example 4 (1) Li6PS5Cl (LPSC) powder (10 g), SBR binder (0.3 g) and xylene solvent were mixed to form a uniform slurry with a solid content of 40 wt% and stirred for 12 hours. The slurry was coated onto a PET release film with a coating thickness of 80 μm and partially dried at 40°C for 5 minutes, controlling the residual solvent content to be about 15 wt%, to obtain a plastic wet electrolyte membrane.

[0052] (2) Place the PI fiber mesh on the surface of the wet electrolyte membrane and roll it into the membrane at 50°C and 1 MPa pressure. Control the embedding depth to be 50% of the thickness of the wet membrane (about 40 μm) so that the fiber mesh is embedded in the surface area of ​​the membrane.

[0053] (3) The electrolyte membrane after embedding the skeleton was vacuum dried at 80°C for 6 hours to remove the remaining solvent; then it was hot-pressed at 80°C and 30 MPa for 5 minutes to reduce the membrane thickness to 25 μm, thus obtaining the sulfide solid electrolyte membrane with embedded skeleton reinforcement.

[0054] Table 3 Performance of Examples 1-7 and Comparative Examples 1-4 In summary, as shown in Table 2, when the embedding depth increases from 20% to 100%, the tensile strength increases from 4.2 MPa to 11.5 MPa (an increase of 174%), while the ionic conductivity decreases from 2.65 mS / cm to 1.95 mS / cm (a decrease of 26%). A 60% embedding depth represents the optimal balance point: referring to the data for Comparative Example 1 in Table 3, compared to the electrolyte membrane without a framework embedding (around 0.4 MPa), the tensile strength is 8.5 MPa (a 20-fold increase), the ionic conductivity is 2.40 mS / cm (86% retention), and the CCD is 2.5 mA / cm. 2 The invention demonstrates that by precisely controlling the embedding depth, the synergistic optimization of mechanical strength and ionic conductivity can be achieved, which is one of the core technical features of the invention.

[0055] Comparing Examples 1-4 of this application, it can be seen that various binder systems can successfully prepare embedded skeleton reinforced films, with tensile strength increased by 15-20 times; this proves that the present invention has excellent universality and can be adapted to various binder systems.

[0056] Comparing Examples 1-4 of this application with Comparative Example 4, it can be seen that the mechanical strength, ionic conductivity and interface stability of the electrolyte membrane are significantly improved by designing chemical bonding modification of the skeleton surface (such as lithium oxygen bond, amino group, mercapto group, etc.).

[0057] Comparing Examples 5 and 6 and 7 of this application, it can be seen that the electrolyte membrane with a double-layer skeleton embedded (with embedding depths of 20% and 80%) has a significantly improved tensile strength of 12.8 MPa compared to the electrolyte membrane with a single skeleton embedded (with embedding depths of 20% and 80% in Examples 6 and 7, respectively). This allows it to better adapt to changes in the volume of the positive and negative electrodes and meet the application requirements of solid-state batteries. This demonstrates that multi-layer skeleton embedding can achieve "strength superposition" and is suitable for scenarios with extremely high mechanical strength requirements (such as high-pressure operation and large-size batteries).

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an interfacial chemically bonded embedded framework sulfide solid electrolyte membrane, characterized in that, The method includes the following steps: (1) Mix the sulfide electrolyte, binder and organic solvent to prepare a slurry, coat or roll it onto the substrate, and partially dry it until the solvent residue is 5-30 wt% to obtain a plastic wet electrolyte membrane; (2) The porous framework is surface functionalized and then pressed into the wet electrolyte membrane obtained in step (1), with the embedding depth controlled to be 20-90% of the thickness of the wet electrolyte membrane; (3) The electrolyte membrane with embedded skeleton obtained in step (2) is completely dried and then hot-pressed to densify it to obtain an embedded skeleton sulfide solid electrolyte membrane. All steps (1)-(3) are performed in a protective gas atmosphere.

2. The method according to claim 1, characterized in that, In step (1), the sulfide electrolyte includes Li6PS5Cl, Li6PS5Br, Li6PS5I, and Li 10 GeP2S 12 The electrolyte contains at least one of Li3PS4, and the binder includes at least one of styrene-butadiene rubber, polyisobutylene, polyvinyl acetate, hydrogenated nitrile rubber, and polyvinylidene fluoride. The binder accounts for 1-10 wt% of the total mass of the electrolyte, and the organic solvent includes at least one of xylene, toluene, cyclohexane, acetonitrile, tetrahydrofuran, butyl butyrate, n-hexane, and n-heptane.

3. The method according to claim 1, characterized in that, In step (1), the solid content of the slurry is 20-80 wt%, and the temperature of the partial drying is 20-60℃.

4. The method according to claim 1, characterized in that, In step (2), the porous skeleton includes at least one of polymer fiber mesh, metal mesh, nonwoven fabric, and porous ceramic membrane; the pore size of the porous skeleton is 1-100 μm, the porosity is 30-90%, and the thickness is 5-50 μm. The polymer fiber web is made of at least one of polyimide, polyethylene terephthalate, polyacrylonitrile, polyvinylidene fluoride, polyetheretherketone, and polyphenylene sulfide. The metal mesh is made of at least one of stainless steel, nickel, copper, and aluminum, and has an insulating coating on its surface. The material of the nonwoven fabric is selected from at least one of cellulose, polypropylene, and polyethylene; The surface functionalization modification involves introducing functional groups that can form covalent, coordinate, or lithium bonds with sulfide electrolytes or binders. The functional groups include at least one of amino, mercapto, carboxyl, hydroxyl, sulfonic acid, silanol, lithium oxy group, and lithium sulfide group. The modification methods include one or more of plasma treatment, silane coupling agent grafting, or lithium salt grafting.

5. The method according to claim 1, characterized in that, In step (2), the pressing method is selected from at least one of roller pressing, flat plate pressing, and vacuum adsorption. The pressing pressure is 0.1-10 MPa and the pressing temperature is 20-80℃. The pressing temperature is adjusted so that the electrolyte and the skeleton material form in-situ interface bonds and interactions.

6. The method according to claim 1, characterized in that, In step (2), the skeleton is pressed into the wet electrolyte membrane in stages by controlling the pressing pressure and time, so that the skeleton is distributed in a gradient in the direction of membrane thickness: the skeleton density is high on the surface of the membrane and the skeleton density is low inside the membrane.

7. The method according to claim 1, characterized in that, In step (3), the temperature for complete drying is 60-120℃ and the time is 2-12 hours; the temperature for hot pressing densification is 50-100℃, the pressure is 10-50 MPa, and the film thickness after hot pressing is 10-50 μm.

8. A solid electrolyte membrane with an embedded framework of sulfides and enhanced interfacial chemical bonding, characterized in that, Prepared by the method of any one of claims 1-7, comprising a sulfide electrolyte membrane and a porous framework embedded therein.

9. The sulfide solid electrolyte membrane according to claim 8, characterized in that, The porous framework is distributed in a gradient along the thickness direction of the membrane, with the surface framework density being higher than the internal framework density.

10. The sulfide solid electrolyte membrane according to claim 9, characterized in that, The sulfide solid electrolyte membrane has a thickness of 10-50 μm, a tensile strength ≥5 MPa, and an ionic conductivity ≥2.0 mS / cm.

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