Sulfide electrolyte membrane and method for producing the same, solid-state battery

Abstract

The application relates to a sulfide electrolyte film and a preparation method thereof and a solid-state battery, and belongs to the technical field of solid-state batteries.A sulfide electrolyte film comprises a first electrolyte layer, a second electrolyte layer and a first electrolyte layer arranged in sequence; the first electrolyte layer comprises a plurality of sulfide inorganic electrolyte nanosheets, the second electrolyte layer comprises a plurality of sulfide inorganic electrolyte microparticles, the sulfide inorganic electrolyte in the nanosheets and the sulfide inorganic electrolyte in the microparticles have the same chemical composition; the thickness of each nanosheet is less than 400 nm, and the thickness of the first electrolyte layer is greater than or equal to 1 mu m.The sulfide electrolyte film provided by the application can significantly improve the critical current density and the lithium dendrite resistance of a lithium ion battery.

Description

Technical Field

[0001] This application relates to the field of solid-state battery technology, and in particular to a sulfide electrolyte membrane and its preparation method, and a solid-state battery. Background Technology

[0002] Solid-state electrolyte membranes are a key component of solid-state batteries, and sulfide solid-state electrolytes have attracted much attention due to their excellent ion transport properties. Sulfide electrolytes can achieve close packing through simple cold pressing and exhibit ionic conductivity comparable to liquid electrolytes. This makes sulfide electrolytes an important material for improving battery performance, especially showing broad application prospects in high energy density and safety.

[0003] However, in practical applications, sulfide electrolytes are prone to lithium dendrite growth along grain boundaries during charge and discharge. This not only leads to rapid short circuits but also significantly reduces the cycle performance of all-solid-state batteries. To address this issue, researchers have proposed various modification schemes, including adding organic or oxide-inorganic layers to the surface of the sulfide electrolyte membrane to enhance its anti-dendrite ability. However, these methods introduce new materials and interface layers, resulting in poor compatibility between layers and poor stability of the two-phase interface. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the objectives of this application include providing a sulfide electrolyte membrane and its preparation method, as well as a solid-state battery, to improve the critical current density and anti-lithium dendrite ability of the sulfide electrolyte membrane, and to achieve better stability and compatibility between layers.

[0005] In a first aspect, embodiments of this application provide a sulfide electrolyte membrane, comprising a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer disposed sequentially; the first electrolyte layer comprises a plurality of sulfide inorganic electrolyte nanosheets, and the second electrolyte layer comprises a plurality of sulfide inorganic electrolyte micron particles, wherein the sulfide inorganic electrolyte in the nanosheets has the same chemical composition as the sulfide inorganic electrolyte in the micron particles; the thickness of each nanosheet is <400nm, and the thickness of the first electrolyte layer is ≥1μm.

[0006] On the one hand, this application utilizes nanosheets with a thickness of <400 nm. These ultrathin nanosheets possess a higher critical current density than traditional electrolyte particles, and their two-dimensional structure allows for more effective current dispersion during lithium ion migration, thereby reducing local current density and the likelihood of dendrite formation. Furthermore, the use of a multilayer structure combining nanosheet and particle layers effectively improves lithium-ion transport efficiency. Moreover, the two-dimensional characteristics of the nanosheets on both sides of the electrolyte membrane cause lithium dendrites to precipitate more readily on surfaces parallel to the electrodes, rather than perpendicular to them. This characteristic not only reduces the threat of dendrite growth to the battery but also enhances the overall membrane's resistance to dendrite formation, thereby improving battery safety and cycle performance. On the other hand, the nanosheets in this application are made of the same material as the sulfide inorganic electrolyte in micron-sized particles. The interface of identical materials reduces the space charge layer formed by the potential difference between different materials, thus reducing interfacial resistance and improving ion migration efficiency, enabling the battery to maintain good performance even at high currents.

[0007] In some embodiments of this application, the sulfide inorganic electrolyte includes Li7P3S. 11 Li3PS4, Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li6PS5Cl and Li 7-x PS 6-x Cl x Any one of them.

[0008] In some embodiments of this application, the D of micron-sized particles 50 The range is 1-30 μm.

[0009] D of sulfide inorganic electrolyte micron particles 50 Limiting the size to the 1-30μm range not only improves ionic conductivity and film structure stability, but also effectively reduces the risk of lithium dendrite growth, enhancing the material's adaptability and economy.

[0010] In some embodiments of this application, the thickness of the second electrolyte layer is 10-300 μm.

[0011] Limiting the thickness of the second electrolyte layer to the range of 10-300 μm helps improve the overall ionic conductivity of the battery and enhances charge and discharge efficiency. It also makes the electrolyte membrane less prone to cracking during charge and discharge, thus improving battery stability and lifespan. Furthermore, within this thickness range, the electrolyte layer provides sufficient space for lithium ion migration while reducing the concentration of localized current density; this effectively reduces the risk of lithium dendrite growth and improves battery safety.

[0012] In some embodiments of this application, the thickness of the first electrolyte layer is 1-5 μm.

[0013] Limiting the thickness of the first electrolyte layer to within the range of 1-5 μm reduces the diffusion path of lithium ions within the electrolyte, thereby improving ionic conductivity. This also helps improve battery efficiency, reduce energy loss, and enhance cycle performance. Within this 1-5 μm thickness range, the electrolyte layer can effectively control current density and reduce localized current concentration. This helps suppress lithium dendrite formation, reduces short-circuit risk, and enhances battery safety.

[0014] Secondly, embodiments of this application provide a method for preparing the above-mentioned sulfide electrolyte membrane, comprising: mixing and dissolving sulfide inorganic electrolyte nanosheets, a binder, and a solvent to obtain a first slurry; mixing and dissolving sulfide inorganic electrolyte micron particles, a binder, and a solvent to obtain a second slurry; coating the first slurry onto a carrier and drying it to obtain a first electrolyte layer; coating the second slurry onto the first electrolyte layer and drying it to obtain a second electrolyte layer formed on the surface of the first electrolyte layer; coating the first slurry onto the second electrolyte layer, drying it, and rolling it to obtain a sulfide electrolyte membrane; wherein the drying is performed under an inert protective atmosphere or at a dew point of -50°C.

[0015] This preparation method employs a multilayer coating technique to form a first electrolyte layer, a second electrolyte layer, and a second coated first electrolyte layer. Simultaneously, the combination of nanosheets and micron-sized particles effectively suppresses lithium dendrite growth while ensuring lithium-ion transport efficiency, thereby improving battery safety and cycle performance.

[0016] In some embodiments of this application, the adhesive includes any one of hydrogenated styrene-butadiene block copolymer, styrene-butadiene rubber, polyisobutylene, cis-butadiene rubber, and polytetrafluoroethylene.

[0017] Using binders such as hydrogenated styrene-butadiene block copolymer, styrene-butadiene rubber, polyisobutylene, cis-butadiene rubber, and polytetrafluoroethylene can not only improve the adhesion and mechanical strength of the electrolyte membrane, but also enhance its thermal stability and chemical resistance, providing good processability and adaptability.

[0018] In some embodiments of this application, the mass ratio of binder to sulfide inorganic electrolyte nanosheets in the first slurry is (1-15):(99-85).

[0019] Limiting the mass ratio of binder to sulfide inorganic electrolyte nanosheets to the range of (1-15):(99-85) not only enhances adhesion and the mechanical strength of the film, but also optimizes ionic conductivity, improves processability, promotes battery performance balance, reduces costs, and improves long-term stability.

[0020] In some embodiments of this application, the mass ratio of binder to sulfide inorganic electrolyte micron particles in the second slurry is (1-15):(99-85).

[0021] Limiting the mass ratio of binder to sulfide inorganic electrolyte micron particles to the range of (1-15):(99-85) not only improves the mechanical strength and ionic conductivity of the membrane, but also optimizes slurry flowability, improves membrane uniformity and moisture resistance, and reduces production costs.

[0022] In some embodiments of this application, the solvent in the first slurry and the solvent in the second slurry each independently include any one of toluene, xylene, heptane, octane and isobutyl ether.

[0023] These solvents have good solubility, enabling them to dissolve various types of polymers and binders without altering the sulfide electrolyte. For example, toluene and xylene are commonly used organic solvents that can effectively dissolve binders such as hydrogenated styrene-butadiene block copolymers, thereby forming a homogeneous slurry.

[0024] In some embodiments of this application, the mass fraction of sulfide inorganic electrolyte nanosheets in the solvent in the first slurry is 35-80%.

[0025] In some embodiments of this application, the mass fraction of sulfide inorganic electrolyte microparticles in the solvent in the second slurry is 35-80%.

[0026] Limiting the mass fraction of sulfide inorganic electrolyte nanosheets and micron particles in the solvent to the range of 35-80% can not only improve the fluidity of the slurry and the uniformity of the membrane, but also optimize ionic conductivity, enhance the mechanical strength of the membrane, improve drying efficiency, reduce costs and improve environmental friendliness.

[0027] In some embodiments of this application, the inert protective atmosphere includes nitrogen or argon.

[0028] In some embodiments of this application, the drying temperature is 90-150°C and the drying time is 2-10 hours.

[0029] Limiting the drying temperature to 90-150℃ and the drying time to 2-10 hours effectively evaporates the solvent and shortens the drying time. This also improves drying efficiency, membrane density and chemical stability, reduces residual solvent, optimizes battery performance, and lowers costs.

[0030] Thirdly, embodiments of this application provide a solid-state battery, including any of the sulfide electrolyte membranes described above. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of the sulfide electrolyte membrane provided in Embodiment 1 of this application.

[0033] Icons: 1-Second electrolyte layer; 2-First electrolyte layer; 3-Sulfide inorganic electrolyte nanosheets; 4-Sulfide inorganic electrolyte micron particles. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0035] This application provides a sulfide electrolyte membrane, comprising a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer disposed sequentially. The first electrolyte layer comprises a plurality of sulfide inorganic electrolyte nanosheets, and the second electrolyte layer comprises a plurality of sulfide inorganic electrolyte micron particles. The sulfide inorganic electrolyte in the nanosheets has the same chemical composition as the sulfide inorganic electrolyte in the micron particles. The thickness of each nanosheet is <400 nm, and the thickness of the first electrolyte layer is ≥1 μm.

[0036] The design of the sulfide electrolyte membrane in this application enables it to possess a higher critical current density, effectively suppressing lithium dendrite growth and thus reducing the risk of short circuits. Specifically, the ultrathin nanosheets (thickness < 400 nm) used in the sulfide electrolyte membrane provided in this application have a higher critical current density than traditional electrolyte particles. This is because the two-dimensional structure of the ultrathin nanosheets allows for more effective current dispersion when lithium ions migrate on their surface, thereby reducing local current density and decreasing the likelihood of dendrite formation. Furthermore, by using a multilayer structure combining nanosheet layers and particle layers, lithium ion transport efficiency can be effectively improved. Moreover, the two-dimensional characteristics of the nanosheets make lithium dendrites more likely to precipitate on the surface parallel to the electrode, rather than along the direction perpendicular to the electrode. This characteristic not only reduces the threat of dendrite growth to the battery but also improves the overall anti-dendrite capability of the membrane, enhancing battery safety and cycle performance. In addition, since the nanosheets are made of the same material as the sulfide inorganic electrolyte in the micron-sized particles, the interface bonding is tighter, reducing interfacial resistance and improving ion migration efficiency, allowing the battery to maintain good performance even at high currents.

[0037] As an example, the thickness of each nanosheet includes, but is not limited to, 50nm, 70nm, 90nm, 100nm, 120nm, 150nm, 200nm, 240nm, 300nm, 350nm, 380nm, and 400nm.

[0038] As an example, the thickness of the first electrolyte layer includes, but is not limited to, 1.4 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.4 μm, 3.8 μm, 4 μm, 4.3 μm, 4.6 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 9 μm, and 10 μm.

[0039] In the embodiments of this application, the sulfide inorganic electrolyte includes Li7P3S. 11 Li3PS4, Li 10 GeP2S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li6PS5Cl and Li 7-x PS 6-x Cl x Any one of them.

[0040] In this embodiment of the application, the D of the micron-sized particles 50The thickness of the first electrolyte layer is 1-30 μm, and the thickness of the second electrolyte layer is 10-300 μm. As an example, the D of the micron-sized particles... 50 Including but not limited to 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, and 30μm. As an example, the thickness of the second electrolyte layer includes, but is not limited to, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, 250 μm, 260 μm, 270 μm, 280 μm, 290 μm, and 300 μm.

[0041] D of micron-sized particles 50 Within the 1-30 μm range, the specific surface area of ​​the particles can be increased, thereby improving the ion conduction pathway. This helps to improve the overall ionic conductivity of the electrolyte, promotes the rapid migration of lithium ions, and thus improves the charge and discharge efficiency of the battery. The D of micron-sized particles... 50 Particles smaller than 1 μm will result in lower ionic conductivity of the membrane, and may also lead to ineffective isolation between the positive and negative electrodes during battery assembly, causing a short circuit; the D of micron-sized particles 50 Particles larger than 30 μm cannot achieve a sufficiently small overall electrolyte membrane thickness and may lead to a decrease in battery energy density. Within this particle size range, particles can form a dense and uniform membrane structure. This structure helps reduce interface defects and porosity, improves the mechanical strength and stability of the membrane, and thus enhances the battery's cycle performance. Particles within this size range can also create a more uniform electric field distribution within the electrolyte membrane, reducing the concentration of localized current density. This helps suppress lithium dendrite growth, reduces the risk of short circuits, and improves battery safety.

[0042] The thickness of the second electrolyte layer is limited to the range of 10-300 μm, which allows the electrolyte layer to maintain sufficient ion conduction pathways while reducing ion diffusion barriers. This helps to improve the overall ionic conductivity of the battery and enhance charge-discharge efficiency. Electrolyte layers within this thickness range typically possess good mechanical strength and toughness. This makes the electrolyte membrane less prone to cracking during charge-discharge processes, enhancing battery stability and lifespan. It also allows for good contact between the electrolyte layer and the electrodes, reducing interfacial impedance and contributing to improved electrochemical performance and reduced energy loss. Furthermore, within this thickness range, the electrolyte layer provides sufficient space for lithium ion migration while reducing localized current density concentration; this effectively reduces the risk of lithium dendrite growth and improves battery safety.

[0043] The following describes a method for preparing a sulfide electrolyte membrane according to an embodiment of this application.

[0044] A method for preparing a sulfide electrolyte membrane, comprising:

[0045] Step S1: Add the sulfide inorganic electrolyte nanosheets and binder to the solvent in the corresponding mass ratio, stir to dissolve, and obtain the first slurry.

[0046] Step S2: Add the sulfide inorganic electrolyte particles and binder to the solvent in the corresponding mass ratio, stir to dissolve, and obtain the second slurry.

[0047] Step S3: The first slurry obtained in step S1 is coated onto the carrier and dried under an inert protective atmosphere (N2 or Ar) to obtain a first electrolyte layer; the second slurry is coated onto the first electrolyte layer and dried under an inert protective atmosphere (N2 or Ar) to obtain a second electrolyte layer formed on the surface of the first electrolyte layer.

[0048] In this application, the carrier is aluminum foil or an organic release film.

[0049] Step S4: The first slurry obtained in step S1 is coated onto the second electrolyte layer obtained in step S3, dried under an inert protective atmosphere (N2 or Ar), and the composite sheet is rolled into a dense film using a rolling press to obtain the sulfide electrolyte membrane.

[0050] This preparation method employs a multilayer coating technique to form a first electrolyte layer, a second electrolyte layer, and a second coated first electrolyte layer. The multilayer structure optimizes ion conduction pathways, improves interfacial contact, and reduces impedance. The varying thickness and material properties of each layer effectively modulate the overall membrane performance, providing better ionic conductivity and mechanical strength. Using the same sulfide electrolyte material (nanosheets and micron-sized particles) helps improve the bonding between layers. Material consistency reduces interfacial potential differences and defects caused by different materials, thereby lowering interfacial impedance and improving ion migration efficiency. Simultaneously, the combination of nanosheets and micron-sized particles enhances the membrane's mechanical stability while maintaining good conductivity. The high specific surface area of ​​the sulfide nanosheets helps provide more reaction interfaces, enhancing ion conduction, while the sulfide particles provide the necessary structural strength.

[0051] The drying process described above can also be carried out at a dew point of -50°C. Drying under an inert protective atmosphere or at a dew point of -50°C effectively prevents the effects of moisture and oxygen. The protective atmosphere prevents moisture adsorption and oxidation reactions, thereby maintaining the chemical stability of the electrolyte, improving the overall performance of the membrane, and reducing the risk of lithium dendrite formation.

[0052] In the embodiments of this application, the adhesives include, but are not limited to, hydrogenated styrene-butadiene block copolymer (SEBS), styrene-butadiene rubber (SBR), polyisobutylene (PIB), cis-butadiene rubber (BR), and polytetrafluoroethylene (PTFE).

[0053] In the first slurry, the mass ratio of sulfide inorganic electrolyte nanosheets to binder is (99-85):(1-15). For example, the mass ratio of sulfide inorganic electrolyte nanosheets to binder includes, but is not limited to, 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 9:1, 89:11, 88:12, 87:13, 86:14, and 85:15. Limiting the mass ratio of sulfide inorganic electrolyte nanosheets to binder to the range of (99-85):(1-15) can fill the tiny gaps in the electrolyte membrane, provide stronger interfacial bonding, reduce interfacial impedance, and thus improve battery performance. The binder can enhance the toughness of the membrane, preventing it from cracking or peeling due to stress concentration during charging and discharging, thereby improving the integrity and long-term stability of the membrane.

[0054] In the second slurry, the mass ratio of sulfide inorganic electrolyte microparticles to binder is (99-85):(1-15). For example, the mass ratio of sulfide inorganic electrolyte microparticles to binder includes, but is not limited to, 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 9:1, 89:11, 88:12, 87:13, 86:14, and 85:15. Limiting the mass ratio of sulfide inorganic electrolyte microparticles to binder within the range of (99-85):(1-15) helps improve the uniformity and consistency of the membrane, effectively prevents moisture penetration, enhances membrane stability, and avoids performance degradation in humid environments.

[0055] In the embodiments of this application, the solvents in the first slurry and the solvents in the second slurry are each independently including, but not limited to, toluene, xylene, heptane, octane and isobutyl ether. The mass fraction of sulfide inorganic electrolyte nanosheets in the solvent is 35-80%. For example, in the first slurry, the mass fraction of sulfide inorganic electrolyte nanosheets in the solvent includes, but is not limited to, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, and 80%. In the second slurry, the mass fraction of sulfide inorganic electrolyte microparticles in the solvent is 35-80%. For example, the mass fraction of sulfide inorganic electrolyte microparticles in the solvent includes, but is not limited to, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, and 80%.

[0056] In this embodiment, the drying temperature is 90-150℃, and the drying time is 2-10 hours. For example, the drying temperature includes, but is not limited to, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, and 150℃. The drying time includes, but is not limited to, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, and 10 hours.

[0057] Limiting the drying temperature to 90-150℃ and the drying time to 2-10 hours effectively evaporates the solvent and shortens the drying time. Within this temperature range, it promotes the interaction and bonding between materials, resulting in a denser membrane after drying, reduced porosity, and improved mechanical strength; it also helps to minimize the residual solvent content inside the membrane.

[0058] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0059] Example 1

[0060] Figure 1 This is a schematic diagram of the structure of the sulfide electrolyte membrane provided in Embodiment 1 of this application. Please refer to... Figure 1 .

[0061] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0062] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0063] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0064] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0065] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0066] Example 2

[0067] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0068] (1) Li6PS5Cl nanosheets with a thickness of 300nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0069] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0070] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0071] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0072] Example 3

[0073] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0074] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0075] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0076] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 2 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0077] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 2 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0078] Example 4

[0079] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0080] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0081] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0082] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 7 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0083] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 7 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0084] Example 5

[0085] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0086] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0087] (2) D 50 10μm Li6PS5Cl particles and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 hours to dissolve, thus obtaining the second slurry.

[0088] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0089] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0090] Example 6

[0091] This embodiment provides a sulfide electrolyte membrane, the preparation method of which is as follows:

[0092] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0093] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0094] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 60 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0095] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0096] Example 7

[0097] This embodiment is basically the same as Embodiment 1, except that the thickness of the second electrolyte layer is 5 μm.

[0098] Its preparation method is as follows:

[0099] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0100] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0101] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 5 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0102] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0103] Example 8

[0104] This embodiment is basically the same as Embodiment 1, except that the thickness of the second electrolyte layer is 350 μm.

[0105] Its preparation method is as follows:

[0106] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0107] (2) D 50Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0108] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 350 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0109] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0110] Comparative Example 1

[0111] This comparative example is basically the same as Example 1, except that only the second slurry is used to coat the aluminum foil, and the coating thickness is the total coating thickness of Example 1.

[0112] Its preparation method is as follows:

[0113] (1) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining a slurry.

[0114] (2) The slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 28 μm, and dried under N2 (100℃, 4h) to obtain a sulfide electrolyte membrane.

[0115] Comparative Example 2

[0116] This comparative example is basically the same as Example 1, except that the thickness of the first electrolyte layer is 0.5 μm.

[0117] Its preparation method is as follows:

[0118] (1) Li6PS5Cl nanosheets with a thickness of 100nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0119] (2) D 50Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0120] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 0.5 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0121] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 0.5 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0122] Comparative Example 3

[0123] This comparative example is basically the same as Example 1, except that Li6PS5Cl is replaced with the halide electrolyte LiInCl3.

[0124] Its preparation method is as follows:

[0125] (1) LiInCl3 nanosheets with a thickness of 100 nm and SEBS were added to xylene in a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the first slurry.

[0126] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0127] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0128] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0129] Comparative Example 4

[0130] This comparative example is basically the same as Example 1, except that the thickness of each Li6PS5Cl nanosheet is 500nm.

[0131] Its preparation method is as follows:

[0132] (1) Li6PS5Cl nanosheets with a thickness of 500nm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10h to dissolve, thus obtaining the first slurry.

[0133] (2) D 50 Li6PS5Cl particles with a diameter of 3 μm and SEBS were added to xylene at a mass ratio of 98:2 and stirred for 10 h to dissolve, thus obtaining the second slurry.

[0134] (3) The first slurry obtained in step (1) is coated onto aluminum foil, the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h) to obtain the first electrolyte layer (sulfide inorganic electrolyte nanosheet layer); the second slurry obtained in step (2) is coated onto the first electrolyte layer, the coating thickness is controlled to be 20 μm, and dried under N2 (100℃, 4h) to obtain the second electrolyte layer (sulfide inorganic electrolyte nanosheet layer + sulfide inorganic electrolyte particle layer) formed on the surface of the first electrolyte layer.

[0135] (4) The first slurry obtained in step (1) is coated onto the second electrolyte layer obtained in step (3), the coating thickness is controlled to be 4 μm, and dried under N2 (100℃, 4h). The composite sheet is then rolled into a dense film using a rolling press to obtain the sulfide electrolyte film.

[0136] Please refer to Table 1 for the key parameters in Examples 1-8 and Comparative Examples 1-4 above.

[0137] Table 1

[0138]

[0139] Test case

[0140] This test example performs performance tests on the sulfide electrolyte membranes prepared in Examples 1-7 and Comparative Examples 1-4, including critical current density, interfacial impedance, ionic conductivity, and the number of cycles (0.1C / 0.1C) with a capacity retention of 80%.

[0141] 1. The critical current density of a battery can be used to evaluate the ability of a solid electrolyte to suppress lithium dendrites. It is defined as the current density at which lithium dendrites can grow through SEI and SSE and short-circuit the battery. The test method is as follows: A 10mm diameter electrolyte membrane is punched out using a punching machine, lithium metal sheets are placed on both sides of the membrane, and then it is installed into a mold battery to create a symmetrical lithium battery. The critical current density of the battery is tested using a Blue Battery Testing System. The current is set from 0.2mA to 20mA and continuously increased until the battery fails. The test results are shown in Table 2.

[0142] 2. The sulfide electrolyte membranes prepared in Examples 1-7 and Comparative Examples 1-4 were assembled into all-solid-state batteries. Interfacial impedance was tested using an impedance meter, and charge-discharge tests at 0.1C / 0.1C were performed using a Blue Battery testing system. The number of cycles required for capacity decay to 80% of the initial capacity was recorded. The positive electrode formulation of the all-solid-state battery was: NCM622 positive electrode material: Li6PS5Cl: nitrile rubber: acetylene black = 70:26:2:2. The negative electrode was a lithium metal negative electrode, and the operating pressure of the mold battery was 20 MPa.

[0143] 3. Ionic Conductivity Test Method: Take a 10mm diameter electrolyte membrane disc and measure its thickness h and area S. Use two clean, flat 12mm diameter stainless steel discs as current collectors, clamp the electrolyte membrane disc, and then install it into a mold battery. Using a LAND battery testing system, set the mold battery pressure to 30MPa, the test bias voltage to 10mV, and the scanning frequency range to 100kHz~7MHz. Measure its AC impedance spectrum at 25℃ and read the AC impedance R. Calculate the ionic conductivity of the electrolyte membrane using the formula ionic conductivity σ=h / (S*R).

[0144] The results of the above experiments are shown in Table 2:

[0145] Table 2

[0146]

[0147]

[0148] As shown in Table 2, the sulfide electrolyte membrane provided in this application can significantly improve the critical current density of lithium batteries. From Examples 1, 2, and Comparative Example 4, it can be seen that the critical current density of the electrolyte membrane decreases as the thickness of the nanosheets increases. This suggests that due to the two-dimensional characteristics of the ultrathin nanosheets, the exposed crystal surface area in the direction parallel to the electrode is larger, and lithium dendrites precipitated at the interface tend to precipitate on the surface parallel to the electrode rather than along the direction perpendicular to the electrode. Simultaneously, thanks to the short path of the ultrathin nanosheets in the thickness direction, the number of nanosheets required to precipitate dendrites for a short circuit increases as the thickness decreases, thereby improving the overall membrane's resistance to dendrites and short circuits. Furthermore, it can be seen from all examples and Comparative Example 1 that the interfacial impedance of Comparative Example 1 is significantly increased. Therefore, the all-solid-state battery prepared using the sulfide electrolyte membrane provided in this application has lower impedance. This is because the sulfide nanosheets and sulfide particles are the same material, and there is no space charge layer at their interface due to a potential difference.

[0149] By comparing Comparative Example 2 and Example 4, it can be seen that a thickness of 1-5 μm for the first electrolyte layer is more conducive to improving the critical current density of the lithium battery. When the thickness of the first electrolyte layer is less than 1 μm, it will result in weak anti-dendrying ability and limited improvement in critical current density. When the thickness is greater than 5 μm, it will cause higher manufacturing costs and a decrease in battery energy density.

[0150] As can be seen from Examples 1, 7, and 8, a smaller thickness of the second electrolyte layer leads to a decrease in the film's conductivity and critical current density, while a larger thickness of the second electrolyte layer has little impact on the overall conductivity, but the critical current density is somewhat reduced. This is because particulate electrolytes have higher ionic conductivity and lower critical current density than ultrathin nanosheet electrolytes. Particulate electrolytes need to pass through fewer interfaces during transport, hence their higher ionic conductivity. However, because they cannot induce directional lithium deposition like ultrathin nanosheets, their critical current density is lower and their resistance to dendrite formation is weaker.

[0151] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A sulfide electrolyte membrane, characterized by, The sulfide electrolyte film comprises a first electrolyte layer, a second electrolyte layer and a first electrolyte layer arranged in sequence; the first electrolyte layer comprises a plurality of sulfide inorganic electrolyte nanosheets, the second electrolyte layer comprises a plurality of sulfide inorganic electrolyte microparticles, and the sulfide inorganic electrolyte in the nanosheets and the sulfide inorganic electrolyte in the microparticles have the same chemical composition; the thickness of each nanosheet is less than 400 nm, and the thickness of the first electrolyte layer is greater than or equal to 1 μm; and the D50 of the microparticles is 1-30 μm.

2. The sulfide electrolyte film according to claim 1, characterized by The sulfide inorganic electrolyte includes any one of Li7P3S 11 , Li3PS4, Li 10 GeP2S 12 , Li 3.25 Ge 0.25 P 0.75 S4, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , and Li 7-x PS 6-x Cl x (1≤x≤1.7).

3. The sulfide electrolyte film according to claim 2, characterized by The thickness of the second electrolyte layer is 10-300 μm.

4. The sulfide electrolyte membrane according to any one of claims 1 to 3, characterized by The thickness of the first electrolyte layer is 1-5 μm.

5. A method for producing the sulfide electrolyte film according to any one of claims 1 to 4, characterized by, The method comprises: The sulfide inorganic electrolyte nanosheets, a binder and a solvent are mixed and dissolved to obtain a first slurry; The sulfide inorganic electrolyte microparticles, a binder and a solvent are mixed and dissolved to obtain a second slurry; The first slurry is coated on a carrier and dried to obtain the first electrolyte layer; the second slurry is coated on the first electrolyte layer and dried to obtain the second electrolyte layer formed on the surface of the first electrolyte layer; and the first slurry is coated on the second electrolyte layer, dried and rolled to obtain the sulfide electrolyte film. The drying is performed in an inert protective atmosphere or at a dew point of -50 ℃.

6. The production method according to claim 5, wherein The binder in the first slurry and the binder in the second slurry each independently comprises any one of hydrogenated styrene-butadiene block copolymer, styrene-butadiene rubber, polyisobutylene, cis-butadiene rubber and polytetrafluoroethylene; In the first slurry, the mass ratio of the binder to the sulfide inorganic electrolyte nanosheets is (1-15):(99-85); In the second slurry, the mass ratio of the binder to the sulfide inorganic electrolyte microparticles is (1-15):(99-85).

7. The production method according to claim 5, characterized by, The solvent in the first slurry and the solvent in the second slurry each independently comprises any one of toluene, xylene, heptane, octane and isobutyl ether; In the first slurry, the mass fraction of the sulfide inorganic electrolyte nanosheets in the solvent is 35-80%; In the second slurry, the mass fraction of the sulfide inorganic electrolyte microparticles in the solvent is 35-80%.

8. The preparation method according to claim 5, characterized in that, The inert protective atmosphere comprises nitrogen or argon; The temperature of the drying is 90-150 ℃, and the time of the drying is 2-10 h.

9. A solid-state battery, characterized by, The sulfide electrolyte film comprises the sulfide electrolyte film according to any one of claims 1-4.

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