Solid electrolyte membrane, its manufacturing method and uses, and solid-state battery

Abstract

This application relates to the field of battery materials, specifically to a solid electrolyte membrane, its manufacturing method, applications, and solid-state batteries. The solid electrolyte membrane includes a lithium metal stabilizing layer, a lithium dendrite suppression layer, and a high-conductivity layer, which are sequentially stacked. The lithium metal stabilizing layer includes a first sulfide solid electrolyte, the surface of which is covered with a lithium sulfide protective layer. The lithium dendrite suppression layer includes a second sulfide solid electrolyte, the porosity of the lithium dendrite suppression layer is less than 8%, and the high-conductivity layer includes a third sulfide solid electrolyte, the third sulfide solid electrolyte having a Hinkley crystallinity index of greater than 1.1 and a particle size greater than 20 μm. This application uses a single-component sulfide electrolyte without adding a third component, significantly improving the stability of the sulfide solid electrolyte membrane with respect to a lithium metal anode, enhancing the electrolyte membrane's lithium dendrite suppression ability, and maintaining the high conductivity of the sulfide itself.

Description

[Technical Field]

[0001] The present application relates to the field of battery materials technology, specifically to a solid electrolyte membrane, its manufacturing method and applications, and a solid-state battery. [CROSS-REFERENCE TO RELATED APPLICATIONS] This application is a priority application for a Chinese patent filed with the China Patent Office on December 30, 2022, bearing application number 202211741996.2 and titled "Solid electrolyte membrane, its manufacturing method and use, and solid-state battery," the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Compared to liquid batteries, solid-state batteries use non-flammable solid electrolytes instead of flammable organic liquid electrolytes, which significantly improves safety. Solid-state batteries are also better suited to high-energy positive and negative electrodes, reducing the weight of the system and offering a relatively high energy density, which has attracted the attention of industry professionals.

[0003] Among various solid electrolyte systems, sulfide solid electrolytes have advantages such as high processability and high ionic conductivity, making them suitable for a wide range of applications. When lithium metal is used as the anode of a solid-state battery, it offers advantages such as high capacity, abundant resources, low density, and low cost. However, sulfide solid electrolytes are unstable with lithium metal. Furthermore, electrolyte membranes made from sulfide solid electrolyte particles have gaps between the particles, and lithium dendrites can penetrate these gaps and cause short circuits in the battery. This makes sulfide solid electrolytes highly incompatible with lithium metal anodes.

[0004] Currently, to improve the compatibility between sulfide solid electrolytes and lithium metal anodes, a third component is typically introduced between them. For example: [1] A polymer electrolyte is used to isolate the lithium metal anode from the sulfide solid electrolyte, preventing direct contact between them and suppressing their reaction. Furthermore, a relatively dense polymer electrolyte layer can inhibit the growth of lithium dendrites. [2] An inorganic material is used to modify the surface of the lithium metal anode.

[0005] However, there are some problems with improving the compatibility between the sulfide solid electrolyte and the lithium metal anode by introducing a third component: [1] The electrical conductivity of the third component is usually low, which may result in a decrease in the electrical conductivity of the entire system; [2] After the third component is introduced, the interfacial contact between the third component and the sulfide solid electrolyte film is poor due to differences in material strength and mechanical properties; [3] It is difficult to ensure the stability between the third component and the sulfide solid electrolyte. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the technical problem to be solved by the present application is to provide a solid electrolyte membrane, a manufacturing method and use thereof, and a solid-state battery, which overcome the drawbacks of the prior art, in which the compatibility between a sulfide solid electrolyte and a lithium metal negative electrode is improved by introducing a third component, such as low electrical conductivity of the third component and poor interfacial contact between the third component and the sulfide solid electrolyte membrane, making it difficult to ensure stability between the third component and the sulfide solid electrolyte.

[0007] When using sulfide solid electrolytes in lithium metal anode solid-state batteries, the potential at the interface between the sulfide solid electrolyte and lithium metal is 0 V. High-valent elements in the sulfide solid electrolyte are reduced at this potential, causing the electrolyte structure to collapse and forming a mixture with ionic and electronic conductivity. This significantly reduces the electrolyte's ionic conductivity, macroscopically increasing battery polarization and significantly reducing charge / discharge capacity. Furthermore, sulfide solid electrolyte membranes are composed of sulfide solid electrolyte particles, and there are gaps between the particles. Lithium dendrites tend to grow within these gaps. When lithium dendrites grow to penetrate the entire electrolyte membrane, they can cause a short circuit between the positive and negative electrodes, leading to internal short circuits, a sudden drop in battery voltage, and a loss of charge / discharge capacity. [Means for solving the problem]

[0008] In order to solve the above problems, the present application provides a solid electrolyte membrane, which includes a lithium metal stabilization layer, a lithium dendrite suppression layer, and a high conductivity layer, which are sequentially stacked, wherein: the lithium metal stable layer includes a first sulfide solid electrolyte, and a surface of the first sulfide solid electrolyte is covered with a lithium sulfide protective layer; the lithium dendrite-inhibiting layer includes a second sulfide solid electrolyte, and the porosity of the lithium dendrite-inhibiting layer is less than 8%; The high conductivity layer includes a third sulfide solid electrolyte, and the third sulfide solid electrolyte has a Hinkley crystallinity index of >1.1 and a grain size of greater than 20 μm.

[0009] Preferably, the molar ratio of the first sulfide solid electrolyte to lithium sulfide is 1:(0.01 to 0.05).

[0010] Preferably, the particle size of the first sulfide solid electrolyte is less than 5 μm.

[0011] Preferably, the lithium metal stable layer further contains a first binder, and the weight of the first binder is 1% to 5% of the weight of the first sulfide solid electrolyte.

[0012] Preferably, the first binder does not contain a fluoro group.

[0013] Preferably, the first binder includes at least one of styrene butadiene rubber, nitrile rubber, polyethylene, and polypropylene.

[0014] Preferably, the second sulfide solid electrolyte has a Hinkley crystallinity index of 0.8 to 1 and a particle size of less than 0.5 μm.

[0015] Preferably, the lithium dendrite-inhibiting layer further contains a second binder, and the weight of the second binder is 2% to 6% of the weight of the second sulfide solid electrolyte.

[0016] Preferably, the second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyisoprene, nitrile rubber, and styrene butadiene rubber.

[0017] Preferably, the conductivity of the third sulfide solid electrolyte is greater than 7 mS / cm.

[0018] Preferably, the high conductivity layer further contains a third binder, and the weight of the third binder is 0.5 to 1.5% of the weight of the third sulfide solid electrolyte.

[0019] Preferably, the third binder includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polybutene, and polyethylene oxide.

[0020] Preferably, the thicknesses of the lithium metal stable layer, the lithium dendrite suppression layer, and the high conductivity layer may vary within a certain range. For example, the thickness of the lithium metal stable layer may be 10 to 20 μm, the thickness of the lithium dendrite suppression layer may be 10 to 20 μm, and the thickness of the high conductivity layer may be 10 to 20 μm.

[0021] Preferably, the first sulfide solid electrolyte, the second sulfide solid electrolyte, and the third sulfide solid electrolyte may be selected within a certain range. For example, the chemical formulas of the first sulfide solid electrolyte, the second sulfide solid electrolyte, and the third sulfide solid electrolyte may be Li 3.15 P 0.5 S 2.5 Cl 0.65 may be.

[0022] The present application further provides a method for manufacturing the solid electrolyte membrane, which includes the following steps: The first sulfide solid electrolyte is brought into contact with lithium powder to react with it, and the resulting product is subjected to dry film formation to obtain a lithium metal stable layer; preparing the second sulfide solid electrolyte into an electrolyte slurry having a solid content of more than 70%, applying the slurry to a carrier, and drying the carrier to obtain a lithium dendrite-inhibiting layer attached to the carrier; A high conductivity layer is obtained by dry deposition of a third sulfide solid electrolyte, wherein the third sulfide solid electrolyte has a Hinkley crystallinity index of >1.1 and a grain size of >20 μm; The lithium metal stabilizing layer, the lithium dendrite suppressing layer and the high conductivity layer are pressure-bonded together to obtain the solid electrolyte membrane.

[0023] Preferably, the process for preparing the first sulfide solid electrolyte includes: The raw materials for forming the sulfide solid electrolyte are taken and sintered at 400 to 500°C for 10 to 15 hours, and the resulting sintered material is polished until the particle size becomes less than 5 µm, thereby obtaining the first sulfide solid electrolyte.

[0024] Preferably, contacting the first sulfide solid electrolyte with lithium powder to react with it, and then performing dry film formation on the resulting product to obtain a lithium metal stable layer includes: The first sulfide solid electrolyte and the lithium powder are mixed in a molar ratio of 1:(0.01 to 0.05), and the mixture is pulverized in a ball mill at a rotation speed of 150 to 200 rpm for 4 to 8 hours to obtain a first sulfide solid electrolyte having a surface covered with a lithium sulfide protective layer; The first sulfide solid electrolyte having the lithium sulfide protective layer on its surface is mixed with a first binder and subjected to a fiberization treatment, and the resulting powder is rolled to form a film, thereby obtaining the lithium metal stable layer.

[0025] In the process of preparing the lithium metal stable layer, after mixing the first sulfide solid electrolyte with lithium powder, the lithium powder is relatively soft and can uniformly cover the surface of the sulfide solid electrolyte, and the surface of the sulfide solid electrolyte in contact with the lithium powder undergoes a uniform reduction reaction to form a lithium sulfide protective layer. By using a ball mill to grind the first sulfide solid electrolyte and control the contact amount between the sulfide solid electrolyte and lithium metal, the lithium metal can be uniformly contacted with the sulfide solid electrolyte, and the surface of the sulfide solid electrolyte can be controlled and the lithium sulfide protective layer can be uniformly covered, preventing further deterioration of the interface between the sulfide solid electrolyte and lithium metal.

[0026] In addition, the dry film formation process prevents the electrolyte stability from decreasing due to contact between the protected sulfide solid electrolyte and organic solvents. The use of a first binder that does not contain fluoro groups prevents the binder from deteriorating or losing its effectiveness due to direct contact with lithium metal. The fiberization process effectively improves the binding properties of the first binder.

[0027] Preferably, the process for preparing the second sulfide solid electrolyte includes: The raw materials for forming the sulfide solid electrolyte are taken and sintered at 260 to 350°C for 5 to 8 hours, and the obtained sintered material is polished until the particle size becomes less than 5µm, thereby obtaining the second sulfide solid electrolyte.

[0028] Preferably, preparing the second sulfide solid electrolyte into an electrolyte slurry having a solid content of more than 70%, applying the slurry to a carrier, and drying the carrier to obtain a lithium dendrite-inhibiting layer includes the following steps: The second sulfide solid electrolyte is mixed with a solvent, and the second sulfide solid electrolyte is wet-polished until the particle size is less than 0.5 μm, thereby obtaining a second sulfide solid electrolyte dispersion; Dispersing a second binder in the second sulfide solid electrolyte dispersion to prepare an electrolyte slurry having a solid content of more than 70%; The electrolyte slurry is applied to the carrier and dried to obtain the lithium dendrite suppression layer attached to the carrier.

[0029] In the manufacturing process of the second sulfide solid electrolyte, a low-temperature, short-time sintering technique is adopted, which avoids the growth of crystal grains while reducing the crystallinity of the second sulfide solid electrolyte and making the second sulfide solid electrolyte particle powder softer, which is favorable for forming a densified lithium dendrite suppression layer and can improve the flatness of the lithium dendrite suppression layer.

[0030] During the manufacturing process of the lithium dendrite-inhibiting layer, wet polishing of the second sulfide solid electrolyte effectively reduces the particle size of the electrolyte powder, maintains the uniformity of the particle size, and significantly reduces the gaps between particles in the lithium dendrite-inhibiting layer. By controlling the solid content of the electrolyte slurry to greater than 70%, the density of the manufactured lithium dendrite-inhibiting layer can be significantly improved. Preferably, the carrier can be a release film, which can improve the flatness of the lithium dendrite-inhibiting layer.

[0031] Preferably, the process for preparing the third sulfide solid electrolyte includes: The raw materials for forming the sulfide solid electrolyte are taken and sintered at 550 to 630°C for 15 to 20 hours, and the resulting sintered material is polished so that the grain size is larger than 20 μm, thereby obtaining the third sulfide solid electrolyte.

[0032] Preferably, performing dry deposition on the third sulfide solid electrolyte to obtain a high conductivity layer includes: The third binder is subjected to a fiberization treatment to obtain a fiberized third binder; The fiberized third binder and the third sulfide solid electrolyte are uniformly mixed, and the resulting powder is rolled to form a film, thereby obtaining the high conductivity layer.

[0033] In the manufacturing process of the third sulfide solid electrolyte, high-temperature, long-term sintering technology is used to significantly improve the crystallinity and grain size of the electrolyte particles, further improving the electrolyte's electrical conductivity. By controlling the grain size during polishing to be larger than 20 μm, it is possible to avoid the destruction of the crystals during polishing, which would reduce the crystal size and further affect the electrolyte's conductivity.

[0034] The dry deposition technique used in the manufacturing process of the high-conductivity layer avoids the need for external machinery such as a ball mill to grind the electrolyte particles, while also avoiding the reduction in conductivity that would occur if the sulfide solid electrolyte were to come into contact with an organic solvent. In conventional dry deposition methods, the binder and electrolyte particles are mixed together before the fiberization process, thereby providing the binder with binding properties. In contrast, the above-described method fiberizes the third binder before mixing it with the third sulfide solid electrolyte, effectively preventing the particle size from becoming smaller when the third sulfide solid electrolyte particles are ground during the fiberization process. This allows the manufacturing of a high-conductivity layer containing electrolyte particles with larger particle sizes, ensuring the high conductivity of the high-conductivity layer.

[0035] Preferably, before producing the first sulfide solid electrolyte, the second sulfide solid electrolyte, and the third sulfide solid electrolyte, the method may further include a step of pulverizing raw materials for forming the sulfide solid electrolytes using a ball mill, where the ball mill may be a planetary ball mill, the rotation speed of the ball mill may be 500 to 700 rpm, and the grinding time may be 10 to 30 hours.

[0036] Preferably, the raw materials for forming the sulfide solid electrolyte may be selected within a certain range. For example, the raw materials for forming the sulfide solid electrolyte may include LiCl, LiS, and PS, and the molar ratio of LiCl, LiS, and PS may be 2.6:5:1.

[0037] Preferably, obtaining the solid electrolyte membrane by pressing the lithium metal stabilization layer, the lithium dendrite suppression layer, and the high conductivity layer includes: the high conductivity layer and the surface of the lithium dendrite suppression layer that is not in contact with the support are bonded together, and a pressure of 300 to 500 MPa is applied for 10 to 30 minutes to obtain an intermediate product that is attached to the support; The support is removed, and the surface of the intermediate product that contacts the support and the lithium metal stabilizing layer are attached together and rolled to obtain the solid electrolyte membrane.

[0038] In the manufacturing process of the solid electrolyte membrane, the high conductivity layer and the lithium dendrite suppression layer are pressed together at a pressure of 300 to 500 MPa for 10 to 30 minutes, thereby further densifying the lithium dendrite suppression layer and ensuring that the porosity of the lithium dendrite suppression layer is less than 8%.

[0039] The present application further provides a use of the above solid electrolyte membrane in the manufacture of a solid-state battery, the solid-state battery having a lithium metal anode.

[0040] The present invention further provides a solid-state battery, which includes the solid electrolyte membrane and a lithium metal negative electrode. [Effects of the Invention]

[0041] The technical solution of the present application has the following advantageous effects:

[0042] The solid electrolyte membrane provided by the present application includes a lithium metal stabilizing layer, a lithium dendrite suppression layer, and a high conductivity layer, which are sequentially stacked, and all three functional layers are manufactured using a single sulfide solid electrolyte component. This effectively overcomes the problems that arise when introducing a third component, such as the low conductivity of the third component present, poor interfacial contact between the third component and the sulfide solid electrolyte membrane, and the difficulty in ensuring stability between the third component and the sulfide solid electrolyte.

[0043] Specifically, the lithium metal stable layer includes a first sulfide solid electrolyte, and the surface of the first sulfide solid electrolyte is covered with a lithium sulfide protective layer, so that the lithium sulfide protective layer can effectively prevent the reaction between the sulfide solid electrolyte and the lithium metal negative electrode from continuing, and further improve the stability of the sulfide solid electrolyte film with respect to the lithium metal negative electrode.

[0044] The lithium dendrite-inhibiting layer contains a second sulfide solid electrolyte, and the porosity of the lithium dendrite-inhibiting layer is less than 8%, which results in a high density of the lithium dendrite-inhibiting layer, effectively preventing the growth of lithium dendrites between electrolyte particles, and further enhancing the ability of the electrolyte membrane to inhibit lithium dendrites, thereby achieving the effect of effectively inhibiting the growth of lithium dendrites.

[0045] The high conductivity layer includes a third sulfide solid electrolyte, and the third sulfide solid electrolyte has a Hinkley crystallinity index of >1.1 and a particle size of >20 μm. By controlling the third sulfide solid electrolyte to have a high crystallinity and particle size, the conductivity of the high conductivity layer is further significantly improved, and the solid electrolyte membrane of the present application can maintain the high conductivity of the sulfide itself.

[0046] Therefore, the solid electrolyte membrane of the present application does not incorporate a third component and uses a single-component sulfide as the electrolyte, which significantly improves the stability of the sulfide solid electrolyte membrane with respect to the lithium metal anode, enhances the lithium dendrite suppression ability of the electrolyte membrane, and maintains the high conductivity of the sulfide itself, ultimately effectively improving the cycling performance and power supply performance of the sulfide solid electrolyte-lithium metal anode solid battery. [Brief explanation of the drawings]

[0047] In order to more clearly describe the specific embodiments of the present application or the technical solutions of the existing technology, the drawings used to describe the specific embodiments or the existing technology will be briefly introduced below. Obviously, the drawings used in the following description are part of the embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

[0048] [Figure 1] FIG. 1 is an electron microscope scan of the lithium metal stable layer obtained in step (1) of Example 1 of the present application. [Figure 2] FIG. 2 is an electron microscope scan of the intermediate product obtained in step (4) of Example 1 of the present application. [Figure 3] FIG. 3 is a schematic diagram of the structure of the solid electrolyte membrane obtained in Example 1 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0049] The following examples are provided for a better understanding of the present application, but are not intended to limit the present application to the above preferred embodiments, and do not limit the content and scope of protection of the present application. Any products similar or similar to the present application obtained by taking inspiration from the present application or by combining the present application with features of other prior art shall be protected by the present application.

[0050] Unless specific experimental procedures or conditions are specified in the examples, they can be carried out in accordance with the operations or conditions of conventional experimental procedures described in the literature of the art. Reagents and instruments used without specifying the manufacturer are conventional reagents and instruments available on the market. [Example]

[0051] Example 1 A solid electrolyte membrane is produced by the following method. (1) Manufacturing of lithium metal stabilization layer: [1] LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain the raw material for forming the sulfide solid electrolyte. [2] The raw materials for forming the sulfide solid electrolyte are taken and sintered at 460°C for 12 hours. The sintered material is then polished until the powder particle size is less than 5 μm, to obtain the first sulfide solid electrolyte. [3] The first sulfide solid electrolyte is mixed with lithium powder in a molar ratio of 1:0.02, and then pulverized and mixed using a planetary ball mill at 160 rpm for 6 hours to obtain a first sulfide solid electrolyte having a lithium sulfide protective layer on its surface. [4] 10 g of the first sulfide solid electrolyte having the lithium sulfide protective layer on its surface and 0.2 g of styrene butadiene rubber are mixed, and a grinding machine is used to apply external shear force to perform a fiberization process. Then, a rolling mill is used to roll the powder after the fiberization process, thereby forming an independently formed lithium metal stable layer.

[0052] The chemical formula of the lithium metal stabilization layer produced here is Li 3.15 P 0.5 S 2.5 Cl 0.65 The results of scanning using a scanning electron microscope are shown in FIG. 1. As can be seen from FIG. 1, the surfaces of the electrolyte particles in the lithium metal stable layer are uniformly covered with a lithium sulfide protective layer, and the molar ratio of the first sulfide solid electrolyte to lithium sulfide is calculated to be 1:0.02.

[0053] (2) Manufacturing of the lithium dendrite suppression layer: [1] LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain the raw material for forming the sulfide solid electrolyte. [2] The raw materials for forming the sulfide solid electrolyte are taken and sintered at 280°C for 6 hours. The sintered material is then polished until the powder particle size is less than 5 μm to obtain the second sulfide solid electrolyte. [3] The second sulfide solid electrolyte is mixed with a solvent, toluene, and wet-pulverized using a pot mill until the particle size of the second sulfide solid electrolyte is less than 0.5 μm, thereby obtaining a dispersion of the second sulfide solid electrolyte. [4] Polyvinylidene fluoride is dissolved in the dispersion of the second sulfide solid electrolyte obtained in step [3] so that the amount of polyvinylidene fluoride used is 2% of the amount of second sulfide solid electrolyte used, and the mixture is dispersed using a pot mill to prepare an electrolyte slurry with a solid content of 73%. [5] The electrolyte slurry is applied to a release film to a thickness of 15 μm, and after drying, a lithium dendrite suppression layer is obtained that adheres to the release film.

[0054] The chemical formula of the sulfide solid electrolyte in the lithium dendrite suppression layer manufactured here is Li 3.15 P 0.5 S 2.5 Cl 0.65 and the Hinkley crystallinity index of the sulfide solid electrolyte is measured to be 0.86.

[0055] (3) Manufacturing of high conductivity layers: [1] LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain the raw material for forming the sulfide solid electrolyte. [2] The raw materials for forming the sulfide solid electrolyte are sintered at 570°C for 18 hours, and the sintered material is polished to control the powder particle size after polishing to be greater than 20μm. A third sulfide solid electrolyte is obtained, whose Hinkley crystallinity index is 1.21 and conductivity is 7.6mS / cm. [3] Polytetrafluoroethylene is taken and subjected to a fiberization process using an air flow polisher to give it cohesive properties, thereby obtaining fiberized polytetrafluoroethylene. [4] 10 g of the above-mentioned tertiary sulfide solid electrolyte and 0.05 g of fiberized polytetrafluoroethylene are mechanically mixed using a mixer, and the mixed powder is rolled using a rolling mill to form an independently formed high conductivity layer.

[0056] The chemical formula of the sulfide solid electrolyte in the high conductivity layer produced here is Li 3.15 P 0.5 S 2.5 Cl 0.65 It is measured to be.

[0057] (4) Manufacturing of solid electrolyte membranes: [1] The high conductivity layer obtained in step (3) and the non-release film contact surface of the lithium dendrite suppression layer obtained in step (2) are bonded together, and a pressure of 420 MPa is applied for 20 minutes to obtain an intermediate product that adheres to the release film. The results of scanning electron microscopy of the intermediate product are shown in Figure 2. As can be seen from Figure 2, the electrolyte particles in the upper lithium dendrite-inhibiting layer are significantly smaller, with tighter particle-to-particle contact and a porosity of 6%, which can inhibit lithium dendrite growth. The electrolyte particles in the lower high conductivity layer have larger particle sizes, which are beneficial for lithium ion transmission and improved crystallinity, resulting in higher conductivity. [2] The release film attached to the intermediate product is peeled off, and the surface of the intermediate product that has been peeled off from the release film and is in contact with the release film is bonded to the lithium metal stabilization layer obtained in step (1), and rolled using a rolling mill to obtain a solid electrolyte membrane.

[0058] As shown in Figure 3, the solid electrolyte membrane produced in this example consists of a lithium metal stabilization layer, a lithium dendrite suppression layer, and a high conductivity layer, which are laminated in this order, with a total thickness of 50 μm, of which the high conductivity layer is 20 μm thick, the lithium dendrite suppression layer is 10 μm thick, and the lithium metal stabilization layer is 20 μm thick. [Example]

[0059] Example 2 A solid electrolyte membrane was prepared according to the method of Example 1, except that the steps of this example were When producing the lithium metal stable layer in (1), the sintering temperature in operation [2] is 400°C, the sintering time is 15 hours, the molar ratio of the first sulfide solid electrolyte to lithium powder in operation [3] is 1:0.01, and the amount of the first sulfide solid electrolyte used in operation [4] is 10 g, and the amount of styrene butadiene rubber used is 0.5 g.

[0060] In the solid electrolyte membrane produced in this example, the molar ratio of the first sulfide solid electrolyte to lithium sulfide in the lithium metal stable layer was 1:0.01. [Example]

[0061] Example 3 A solid electrolyte membrane was prepared according to the method of Example 1, except that in step (1) of this example, when preparing a lithium metal stable layer, the sintering temperature in operation [2] was 500°C and the sintering time was 10 hours, the molar ratio of the first sulfide solid electrolyte to lithium powder in operation [3] was 1:0.05, and the amount of the first sulfide solid electrolyte used in operation [4] was 10 g and the amount of styrene-butadiene rubber used was 0.1 g.

[0062] In the solid electrolyte membrane produced in this example, the molar ratio of the first sulfide solid electrolyte to lithium sulfide in the lithium metal stable layer was 1:0.05. [Example]

[0063] Example 4 A solid electrolyte membrane was prepared according to the method of Example 1, except that in step (2) of this example, when preparing the lithium dendrite suppression layer, the sintering temperature in operation [2] was 260°C and the sintering time was 8 hours, the amount of polyvinylidene fluoride used in operation [4] was 3% of the amount of second sulfide solid electrolyte used, and the solid content of the electrolyte slurry after dispersion was 71%.

[0064] In the solid electrolyte membrane produced in this example, the porosity of the lithium dendrite-inhibiting layer is 5%, and the crystallinity of the sulfide solid electrolyte is 0.81. [Example]

[0065] Example 5 A solid electrolyte membrane was prepared according to the method of Example 1, except that in step (2) of this example, when preparing the lithium dendrite suppression layer, the sintering temperature in operation [2] was 350°C and the sintering time was 5 hours, the amount of polyvinylidene fluoride used in operation [4] was 6% of the amount of second sulfide solid electrolyte used, and the solid content of the electrolyte slurry after dispersion was 70%.

[0066] In the solid electrolyte membrane produced in this example, the porosity of the lithium dendrite-suppressing layer is 6%, and the crystallinity of the sulfide solid electrolyte is 0.86. [Example]

[0067] Example 6 A solid electrolyte membrane was prepared according to the method of Example 1, except that in step (3) of this example, when the high conductivity layer was prepared, the sintering temperature in operation [2] was 550°C, the sintering time was 20 hours, and the amount of tertiary sulfide solid electrolyte used in operation [4] was 10 g, and the amount of fiberized polytetrafluoroethylene used was 0.1 g.

[0068] In the solid electrolyte membrane produced in this example, the Hinkley crystallinity index of the sulfide solid electrolyte in the high conductivity layer is 1.15, and the conductivity is 7.2 mS / cm. [Example]

[0069] Example 7 A solid electrolyte membrane was prepared according to the method of Example 1, except that in step (3) of this example, when the high conductivity layer was prepared, the sintering temperature in operation [2] was 630°C, the sintering time was 15 hours, and the amount of tertiary sulfide solid electrolyte used in operation [4] was 10 g, and the amount of fiberized polytetrafluoroethylene used was 0.06 g.

[0070] In the solid electrolyte membrane produced in this example, the degree of crystallinity of the sulfide solid electrolyte in the high conductivity layer is 1.32, and the conductivity is 7.9 mS / cm.

[0071] Comparative Example 1 A solid electrolyte membrane is prepared by the following method: (1) LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain raw materials for forming a sulfide solid electrolyte. (2) The raw materials for forming the sulfide solid electrolyte are taken and sintered at 460°C for 12 hours. The sintered material is then polished until the powder particle size is less than 5 μm, and the sulfide solid electrolyte is obtained. (3) The sulfide solid electrolyte is mixed with lithium powder in a molar ratio of 1:0.02, and then pulverized and mixed using a planetary ball mill at 160 rpm for 6 hours to obtain a sulfide solid electrolyte with a lithium sulfide protective layer on the surface. (4) 10 g of the sulfide solid electrolyte having the lithium sulfide protective layer on its surface and 0.2 g of styrene butadiene rubber are mixed, and a fiberization process is carried out by applying external shear force using a grinder. After that, the powder after the fiberization process is rolled using a rolling mill to form a solid electrolyte membrane with a thickness of 50 μm.

[0072] Comparative Example 2 A solid electrolyte membrane is prepared by the following method: (1) LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain raw materials for forming a sulfide solid electrolyte. (2) The raw materials for forming the sulfide solid electrolyte are taken and sintered at 280°C for 6 hours. The sintered material is then polished until the powder particle size is less than 5 μm, and the sulfide solid electrolyte is obtained. (3) The sulfide solid electrolyte is taken and mixed with a solvent, toluene, and wet-pulverized using a pot mill until the particle size of the sulfide solid electrolyte becomes less than 0.5 μm, thereby obtaining a dispersion of the sulfide solid electrolyte. (4) Polyvinylidene fluoride is dissolved in the sulfide solid electrolyte dispersion obtained in step [3] so that the amount of polyvinylidene fluoride used is 2% of the amount of second sulfide solid electrolyte used, and the solution is dispersed using a pot mill to prepare an electrolyte slurry with a solid content of 73%. (5) The electrolyte slurry is applied to a release film to a thickness of 90 μm, and a solid electrolyte membrane having a thickness of 50 μm after drying is obtained.

[0073] Comparative Example 3 A solid electrolyte membrane is prepared by the following method: (1) LiCl, Li2S, and P2S5 were mixed in a molar ratio of 2.6:5:1 and ground using a planetary ball mill at 550 rpm for 20 h to obtain raw materials for forming a sulfide solid electrolyte. (2) The raw materials for forming the sulfide solid electrolyte are taken and sintered at 570°C for 18 hours. The sintered material is then polished to a powder particle size of >20μm after polishing. The sulfide solid electrolyte is obtained, and its Hinkley crystallinity index is measured to be 1.21 and its electrical conductivity is measured to be 7.6mS / cm. (3) Polytetrafluoroethylene is taken and subjected to a fiberization treatment using an air flow polisher to give it cohesive strength, thereby obtaining fiberized polytetrafluoroethylene. (4) 10 g of the sulfide solid electrolyte and 0.05 g of fibrous polytetrafluoroethylene are mixed mechanically using a stirrer, and the mixed powder is rolled using a rolling mill to form a solid electrolyte membrane with a thickness of 50 μm.

[0074] Comparative Example 4 A solid electrolyte membrane is prepared by the following method: (1) A lithium metal stabilization layer having a thickness of 25 μm is produced by the method shown in step (1) of Example 1, and a lithium dendrite suppression layer having a thickness of 25 μm is produced by the method shown in step (2) of Example 1. (2) The release film attached to the lithium dendrite-suppressing layer is peeled off, and the surface of the lithium dendrite-suppressing layer that has been peeled off from the release film that comes into contact with the release film is bonded to the lithium metal stabilizing layer, and the resulting mixture is rolled using a rolling mill to obtain a solid electrolyte membrane having a thickness of 50 μm.

[0075] Comparative Example 5 A solid electrolyte membrane is prepared by the following method: (1) A lithium metal stable layer having a thickness of 25 μm is produced by the method shown in step (1) of Example 1, and a high conductivity layer having a thickness of 25 μm is produced by the method shown in step (3) of Example 1. (2) The lithium metal stable layer and the high conductivity layer are bonded together and rolled using a rolling mill to obtain a solid electrolyte membrane with a thickness of 50 μm.

[0076] Comparative Example 6 A solid electrolyte membrane is prepared by the following method: (1) A lithium dendrite suppression layer having a thickness of 25 μm is produced by the method shown in step (2) of Example 1, and a high conductivity layer having a thickness of 25 μm is produced by the method shown in step (3) of Example 1. (2) The high conductivity layer and the non-release film contact surface of the lithium dendrite suppression layer are bonded together, and a pressure of 420 MPa is applied for 20 minutes to obtain a solid electrolyte membrane having a thickness of 50 μm.

[0077] Test Example The solid electrolyte membranes produced in Examples 1 to 7 and Comparative Examples 1 to 6 were used to produce all-solid-state batteries, respectively, and the production method was as follows.

[0078] The cathode active material NCM811, solid electrolyte Li6PS5Cl, binder polyvinylidene fluoride, and conductive carbon SP were mixed in a weight ratio of 60:30:5:5 to obtain cathode slurry, which was then coated onto the surface of aluminum foil to obtain the cathode. A piece of lithium metal was used as the anode, and the cathode, solid electrolyte membrane, and anode were assembled in the usual way to form an all-solid-state battery.

[0079] Using a charge / discharge test system, each solid-state battery was subjected to a multiplication performance test at multiplication rates of 0.33C, 1C, and 4C. The test method was as follows: (1) 0.33C discharge specific capacity: Using LAND test equipment, charge at 0.33C constant current, charge cut-off voltage is 4.2V, and discharge at the same current constant current, discharge cut-off voltage is 3V. (2) 1C discharge specific capacity: Using LAND test equipment, charging at 1C constant current, the charge cut-off voltage is 4.2V, and discharging at the same current constant current, the discharge cut-off voltage is 3V. (3) 4C discharge specific capacity: Using LAND test equipment, charge at 4C constant current, the charge cut-off voltage is 4.2V, and discharge at the same constant current, the discharge cut-off voltage is 3V. (4)4C / 0.33C retention rate: 4C discharge specific capacity / 0.33 discharge specific capacity. (5) 50-week cycling retention rate: Using LAND test equipment, charge at 1C constant current, charge cut-off voltage is 4.2V, and discharge at the same current, discharge cut-off voltage is 3V, cycling for 50 weeks.

[0080] The test results are shown in Table 1. [Table 1]

[0081] An all-solid-state battery was fabricated using the solid electrolyte membrane of Comparative Example 1. After cycling for 23 weeks, the solid electrolyte membrane was pierced by lithium dendrites inside the battery, causing a short circuit. This was because the solid electrolyte membrane only had a lithium metal stabilizing layer and did not contain a lithium dendrite suppressing layer.

[0082] An all-solid-state battery was fabricated using the solid electrolyte membrane of Comparative Example 2, and the retention rate after 50 weeks of cycling was 62.3%, much lower than the 93.5% of Example 1. This is because the sulfide solid electrolyte in the solid electrolyte layer of Comparative Example 2 reacted with the lithium metal anode, causing the structure of the electrolyte to collapse and forming a mixed product of ionic and electronic conductivity, resulting in a significant decrease in the ionic conductivity of the electrolyte, ultimately resulting in increased battery polarization, a significant decrease in charge / discharge capacity, and a rapid decline in battery capacity.

[0083] An all-solid-state battery was manufactured using the solid electrolyte membrane of Comparative Example 3, and during the first week of cycling, the solid electrolyte membrane was pierced by lithium dendrites, causing a short circuit in the battery. This was because the solid electrolyte layer only had a high conductivity layer, and the electrolyte particle size in the high conductivity layer was large, resulting in large gaps between the particles, allowing lithium dendrites to grow in the gaps and cause a short circuit in the battery.

[0084] An all-solid-state battery was manufactured using the solid electrolyte membrane of Comparative Example 4, and the 4C / 0.33C capacity retention was 73.6%, significantly lower than the 84.5% of Example 1. This is because the solid electrolyte membrane obtained in Comparative Example 4 did not have a high conductivity layer, and its conductivity was lower than that of the solid electrolyte membrane obtained in Example 1, resulting in poor power-saving performance.

[0085] An all-solid-state battery was manufactured using the solid electrolyte membrane of Comparative Example 5. After cycling for up to 11 weeks, the solid electrolyte membrane was pierced by lithium dendrites inside the battery, causing a short circuit. This was because the solid electrolyte membrane did not have a lithium dendrite-suppressing layer.

[0086] An all-solid-state battery was fabricated using the solid electrolyte membrane of Comparative Example 6, and the retention rate after 50 weeks of cycling was 42.6%, much lower than the 93.5% of Example 1. This is because the solid electrolyte layer of Comparative Example 6 did not have a lithium metal stabilizing layer, and the sulfide solid electrolyte reacted with the lithium metal anode, causing the structure of the electrolyte itself to collapse and forming a mixture of ionic and electronic conductive products, which significantly reduced the ionic conductivity of the electrolyte, ultimately resulting in increased battery polarization, a significant decrease in charge / discharge capacity, and a rapid decline in battery capacity.

[0087] Obviously, the above examples are for the purpose of clearly illustrating the examples, and are not intended to limit the embodiments. Those skilled in the art can make other different types of changes and variations based on the above description. It is not necessary to list all the embodiments here. Any obvious changes or variations made based thereon are still within the scope of the present invention.

Claims

1. A solid electrolyte membrane including a lithium metal stabilizing layer, a lithium dendrite suppressing layer, and a high conductivity layer, which are sequentially stacked, the lithium metal stable layer includes a first sulfide solid electrolyte, and a lithium sulfide protective layer is coated on a surface of the first sulfide solid electrolyte; the lithium dendrite-inhibiting layer includes a second sulfide solid electrolyte, and the porosity of the lithium dendrite-inhibiting layer is less than 8%; The solid electrolyte membrane, wherein the high conductivity layer includes a third sulfide solid electrolyte, and the third sulfide solid electrolyte has a Hinkley crystallinity index of >1.1 and a grain size of greater than 20 μm.

2. the molar ratio of the first sulfide solid electrolyte to lithium sulfide is 1:(0.01 to 0.05); Preferably, the particle size of the first sulfide solid electrolyte is less than 5 μm, Preferably, the lithium metal stability layer includes a first binder, and the weight of the first binder is 1% to 5% of the weight of the first sulfide solid electrolyte; Preferably, the first binder does not contain a fluoro group; 2. The solid electrolyte membrane according to claim 1, wherein the first binder preferably contains at least one of styrene butadiene rubber, nitrile rubber, polyethylene, and polypropylene.

3. The second sulfide solid electrolyte has a Hinkley crystallinity index of 0.8 to 1 and a particle size of less than 0.5 μm; Preferably, the lithium dendrite suppression layer further includes a second binder, and the weight of the second binder is 2% to 6% of the weight of the second sulfide solid electrolyte; 2. The solid electrolyte membrane according to claim 1, wherein the second binder preferably contains at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyisoprene, nitrile rubber, and styrene-butadiene rubber.

4. The conductivity of the third sulfide solid electrolyte is greater than 7 mS / cm; Preferably, the high conductivity layer further includes a third binder, and the weight of the third binder is 0.5 to 1.5% of the weight of the third sulfide solid electrolyte; 2. The solid electrolyte membrane according to claim 1, wherein the third binder preferably contains at least one of polytetrafluoroethylene, polyvinylidene fluoride, polybutene, and polyethylene oxide.

5. The following steps, contacting the first sulfide solid electrolyte with lithium powder to react with it, and then dry-forming the resulting product to obtain a lithium metal stable layer; preparing the second sulfide solid electrolyte into an electrolyte slurry having a solid content of more than 70%, applying the slurry to a carrier, and drying the slurry to obtain a lithium dendrite suppression layer attached to the carrier; dry-coating a third sulfide solid electrolyte to obtain a high conductivity layer, wherein the third sulfide solid electrolyte has a Hinkley crystallinity index of >1.1 and a grain size of >20 μm; a step of compressing the lithium metal stabilization layer, the lithium dendrite suppression layer, and the high conductivity layer to obtain the solid electrolyte membrane; The method for producing a solid electrolyte membrane according to any one of claims 1 to 4, comprising:

6. The preparation process of the first sulfide solid electrolyte includes: A raw material for forming a sulfide solid electrolyte is taken and sintered at 400 to 500 ° C for 10 to 15 hours, and the obtained sintered material is polished until the particle size is less than 5 μm, thereby obtaining the first sulfide solid electrolyte; Preferably, contacting the first sulfide solid electrolyte with lithium powder to react with it, and then dry-forming the resulting product to obtain a lithium metal stable layer includes: The first sulfide solid electrolyte and the lithium powder are mixed in a molar ratio of 1:(0.01 to 0.05) and pulverized using a ball mill at a rotation speed of 150 to 200 rpm for 4 to 8 hours to obtain a first sulfide solid electrolyte having a surface covered with a lithium sulfide protective layer; 6. The manufacturing method according to claim 5, wherein the first sulfide solid electrolyte having the lithium sulfide protective layer on its surface is mixed with a first binder and subjected to a fiberization treatment, and the obtained powder is rolled to form a film, thereby obtaining the lithium metal stable layer.

7. The preparation process of the second sulfide solid electrolyte includes: The raw material for forming the sulfide solid electrolyte is taken and sintered at 260 to 350 ° C for 5 to 8 hours, and the obtained sintered material is polished until the particle size is less than 5 μm, thereby obtaining the second sulfide solid electrolyte; Preferably, preparing the second sulfide solid electrolyte into an electrolyte slurry having a solid content of more than 70%, applying the slurry to a carrier, and drying the slurry to obtain a lithium dendrite suppression layer includes the following steps: The second sulfide solid electrolyte is mixed with a solvent and wet-polished until the particle size of the second sulfide solid electrolyte is less than 0.5 μm, thereby obtaining a second sulfide solid electrolyte dispersion; Dispersing a second binder in the second sulfide solid electrolyte dispersion to prepare an electrolyte slurry having a solid content of more than 70%; 6. The manufacturing method according to claim 5, wherein the electrolyte slurry is applied to the support and dried to obtain the lithium dendrite suppression layer attached to the support.

8. The preparation process of the third sulfide solid electrolyte includes: A raw material for forming a sulfide solid electrolyte is taken and sintered at 550 to 630°C for 15 to 20 hours, and the obtained sintered material is polished until the particle size is larger than 20 μm, thereby obtaining the third sulfide solid electrolyte; Preferably, performing dry film formation on the third sulfide solid electrolyte to obtain a high conductivity layer includes: subjecting the third binder to a fiberization treatment to obtain a fiberized third binder; 6. The manufacturing method according to claim 5, wherein the fiberized third binder and the third sulfide solid electrolyte are uniformly mixed, and the obtained powder is rolled to form a film, thereby obtaining the high conductivity layer.

9. The use of the solid electrolyte membrane in the manufacture of a solid battery according to any one of claims 1 to 4, characterized in that the solid battery uses lithium metal as the negative electrode.

10. A solid-state battery comprising the solid electrolyte membrane according to any one of claims 1 to 4 and a lithium metal negative electrode.

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