Polymer-coated halide solid-state electrolyte, method of making a solid-state battery

Abstract

This invention discloses a method for preparing a polymer-coated halide solid electrolyte and a solid-state battery. The method involves dissolving a polymer in an oily solvent to form a solution, then adding the halide solid electrolyte to the solution to form a solid electrolyte suspension. The solid electrolyte suspension is then dried to obtain the polymer-coated halide solid electrolyte. The solid-state battery uses the polymer-coated halide solid electrolyte to prepare the solid electrolyte separator layer. This invention not only effectively leverages the advantages of halide electrolytes but also avoids the problems of deliquescence and difficulty in dehydration during storage and use, effectively solving physical contact issues and improving ion conduction capability. This addresses the problems of poor electrolyte processability, numerous material interfaces, and high large-scale production costs in existing solid-state batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium batteries, and particularly relates to a polymer-coated halide solid electrolyte and a method for preparing solid batteries. Background Technology

[0002] Solid-state batteries are the most likely batteries to succeed lithium-ion batteries in recent years. By using solid electrolytes instead of the electrolytes in traditional lithium batteries as the conductive material, the energy density of the battery can be greatly improved. At the same time, it avoids the problems of dendrite formation causing short circuits and violent solvent side reactions that are flammable and explosive in traditional liquid batteries.

[0003] Solid-state electrolytes are crucial for the large-scale application of solid-state batteries. They must not only possess excellent electrochemical performance, but also chemical stability and machinability that are compatible with large-scale production processes. Currently, among the major solid-state electrolytes, sulfide electrolytes have high ionic conductivity but poor chemical stability; oxide and other ceramic solid-state electrolyte systems are complex and have poor machinability, making it difficult to solve physical contact problems; borohydride electrolytes lack thermodynamic stability, compatibility with positive and negative electrodes, and the ability to suppress dendrite growth; polymer solid-state electrolytes require high-temperature operation and have weak ion-conducting capabilities. Therefore, breakthroughs in the large-scale application, production cost, and overall performance of solid-state batteries have been slow to materialize.

[0004] Halogen solid electrolytes possess high ionic conductivity, stable chemical / electrochemical stability, and good ductility, with an ionic conductivity >10 at room temperature. -3 S·cm -1 Solid-state electrolytes exhibit good thermal and electrochemical stability and compatibility with various interfaces, making them highly malleable materials with significant potential in the lithium-ion battery field, particularly in solid-state batteries. Halide solid-state electrolytes, in particular, can be prepared through mechanical ball milling and calcination, exhibiting high ionic conductivity. Due to their high stability, halide solid-state electrolytes can serve as excellent buffer layers between high-voltage positive electrodes and other electrolyte materials; and for materials with weak ionic conductivity, such as graphite, they are excellent anode protective layer materials. However, halide electrolytes are hygroscopic, easily forming water of crystallization that drastically reduces ionic conductivity. Furthermore, their drying and dehydration temperatures exceed 200°C, conflicting with the temperature tolerance of binders in the electrode, thus limiting the large-scale engineering application of these materials.

[0005] In view of the above, the industry urgently needs to develop a new halide solid electrolyte that can not only effectively leverage the advantages of halide electrolytes, but also avoid the problems of deliquescence and difficulty in dehydration during storage and use, effectively solve the physical contact problem, improve ion conduction capability, and thus solve the series of engineering application problems of solid-state batteries mentioned above. Summary of the Invention

[0006] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a method for preparing a polymer-coated halide solid electrolyte and a solid-state battery. The polymer-coated halide solid electrolyte is prepared by polymer-coating a halide electrolyte material. This polymer-coated halide solid electrolyte, when used with water and an oil-based solvent, forms an easy-to-manufacture and high-performance solid-state battery. This method not only effectively leverages the advantages of halide electrolytes but also avoids the problems of deliquescence and difficulty in dehydration during storage and use. It effectively solves physical contact issues, improves ion conduction capability, and thus addresses the problems of poor electrolyte processability, numerous material interfaces, and high large-scale production costs in existing solid-state batteries.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a method for preparing a polymer-coated halide solid electrolyte, wherein a polymer is dissolved in an oily solvent to form a solution, a halide solid electrolyte is added to the solution to form a solid electrolyte suspension, and the solid electrolyte suspension is dried to obtain a polymer-coated halide solid electrolyte.

[0009] Preferably, the polymer is selected from one of PI, PPS, PVDF, PVDF-HFP, and PMMA; and / or

[0010] The oily solvent is selected from one of NMP, tetrahydrofuran, ethylene carbonate, and dimethyl carbonate; and / or

[0011] The halide solid electrolyte is Li a MX b Or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, 0≤c<1; and / or

[0012] In the solution, the concentration of the polymer is 1–15 wt%; and / or

[0013] In the solid electrolyte suspension, the solid content of the halide solid electrolyte is 10–65 wt%; and / or

[0014] The drying method is one of spray drying, vacuum drying, hot air drying, infrared drying, or microwave drying; and / or

[0015] The particle size D50 of the polymer-coated halide solid electrolyte is 0.1–10 μm.

[0016] Preferably, when the drying method is spray drying, the drying temperature is 80–140°C; and / or

[0017] The one with Li a MX b The halide solid electrolyte is selected from one of Li3InCl6, Li3YCl6, Li3ScCl6 or Li3InBr6.

[0018] A second aspect of the present invention provides a polymer-coated halide solid electrolyte material, wherein the polymer-coated halide solid electrolyte material is prepared by the preparation method of the polymer-coated halide solid electrolyte.

[0019] A third aspect of the present invention provides a method for preparing a solid-state battery, wherein the solid electrolyte separator layer of the solid-state battery is prepared using a polymer-coated halide solid electrolyte prepared by the method for preparing polymer-coated halide solid electrolyte as described in the first aspect of the present invention.

[0020] Preferably, the method for preparing the solid-state battery includes the following steps:

[0021] (1) Preparation of negative electrode sheet: The negative electrode material, conductive agent, binder, dispersant, halide solid electrolyte and non-halide solid electrolyte are mixed and slurried to obtain a negative electrode slurry, which is then coated, dried or calcined to obtain a negative electrode sheet;

[0022] (2) Preparation of solid electrolyte isolation layer: The polymer-coated halide solid electrolyte and non-halogen solid electrolyte are added to an oily solvent to obtain an electrolyte slurry, which is then coated onto the negative electrode sheet in step (1). After the electrolyte slurry penetrates into the interior of the negative electrode, it is dried and compacted to obtain a negative electrode sheet coated with a solid electrolyte isolation layer.

[0023] (3) Preparation of positive electrode sheet: The positive electrode material, conductive agent, polymer-coated halide solid electrolyte, non-halogen solid electrolyte, and dispersant are added to an oily solvent and mixed to form a slurry to obtain a positive electrode slurry. Then, the slurry is coated, dried, and compacted to obtain a positive electrode sheet.

[0024] (4) Assembly: The positive electrode sheet and the negative electrode sheet coated with a solid electrolyte isolation layer are assembled into a cell to obtain a solid-state battery.

[0025] Preferably, in step (1):

[0026] The negative electrode material is selected from one of graphite and silicon-carbon negative electrode materials; and / or

[0027] The conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene; and / or

[0028] The dispersant is selected from CMC, PVP, and / or

[0029] The halide solid electrolyte is Li a MX b Or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, 0≤c<1; and / or

[0030] The non-halogenated electrolyte is a ceramic solid electrolyte; and / or

[0031] The drying or calcination temperature is 50–650°C; and / or

[0032] In the negative electrode slurry, the concentration of the halide solid electrolyte is 1–30 wt%; and / or

[0033] The ceramic solid electrolyte is selected from one of LLZO, LLTO, LATP, and LAGP.

[0034] Preferably, in step (2):

[0035] The non-halogenated electrolyte is a polymer solid electrolyte and / or a ceramic solid electrolyte; and / or

[0036] The oily solvent is selected from NMP or tetrahydrofuran; and / or

[0037] The drying temperature is 90–110°C.

[0038] Preferably, in step (2) and / or step (3):

[0039] The polymer solid electrolyte is selected from one of PEO, PVDF-HFP, or PMMA; and / or

[0040] The ceramic solid electrolyte is selected from one of LLZO, LLTO, LATP, or LAGP.

[0041] Preferably, in step (3):

[0042] The cathode material is selected from one of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium manganese oxide; and / or

[0043] The conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene; and / or

[0044] The non-halide solid electrolyte is a polymer solid electrolyte and / or a ceramic solid electrolyte; and / or

[0045] The dispersant is selected from CMC, PVP, and / or

[0046] The oily solvent is selected from NMP or tetrahydrofuran.

[0047] A fourth aspect of the present invention provides a solid-state lithium-ion battery, wherein the solid-state lithium-ion battery is prepared by the method for preparing the solid-state battery.

[0048] The present invention provides a method for preparing a polymer-coated halide solid electrolyte and a solid battery, which has the following advantages:

[0049] 1. The use of polymer-coated halide electrolytes avoids the problems of deliquescence and difficulty in dehydration of halide electrolytes during storage and use;

[0050] 2. The polymer-coated halide electrolyte forms a surface contact on the material by completely dissolving in the negative electrode sheet, while the voids formed after the negative electrode sheet is baked at high temperature are filled by the oil-based electrolyte slurry that is subsequently coated. Therefore, the physical contact problem is effectively solved and the ion conduction capability is improved.

[0051] 3. The solid electrolyte isolation layer formed by polymer-coated halide electrolytes and polymer solid electrolytes and ceramic solid electrolytes takes into account the characteristics of different electrolytes, and makes up for the physical contact problem of ceramic solid electrolytes and the poor room temperature ion conductivity problem when the amount of polymer electrolyte is large. Attached Figure Description

[0052] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0053] Figure 1 This is a schematic diagram of the structure of the polymer-coated halide solid electrolyte of the present invention;

[0054] Figure 2 This is a schematic diagram illustrating the structural principle of the solid-state battery of the present invention. Detailed Implementation

[0055] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0056] Combination Figure 1 As shown, the method for preparing the polymer-coated halide solid electrolyte provided by the present invention involves dissolving the polymer in an oily solvent to form a solution, then adding the halide solid electrolyte to the solution to form a solid electrolyte suspension, and finally drying the solid electrolyte suspension to obtain the polymer-coated halide solid electrolyte. The preparation method of the polymer-coated halide solid electrolyte is as follows:

[0057] (a) Dissolving the polymer in an oily solvent to form a solution: wherein the polymer includes common polymers and polymer electrolytes, such as PI (polyimide), PPS (polyphenylene sulfide), PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), and PMMA (polymethyl methacrylate); the oily solvent is NMP (N-methylpyrrolidone), tetrahydrofuran (THF), ethylene carbonate (EC), and dimethyl carbonate (DMC); the concentration of the polymer in the solution ranges from 1 to 15 wt%.

[0058] (b) A halide solid electrolyte is added to the solution in (a) to form a solid electrolyte suspension; wherein the halide solid electrolyte is mainly Li. a MX b Class or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, 0≤c<1. For example, Li. a MX b Halide solid electrolytes include Li3InCl6, Li3YCl6, Li3ScCl6 and Li3InBr6, etc.; in solid electrolyte suspensions, the solid content of halide solid electrolytes is 10-65 wt%.

[0059] (c) Remove the solvent from the solid electrolyte suspension in (b) and dry it into a polymer-coated halide electrolyte, wherein the drying method includes spray drying, vacuum drying, hot air drying, infrared drying or microwave drying, preferably spray drying, and the drying temperature is 80 to 140°C.

[0060] The structure of the polymer-coated halide electrolyte prepared in the above process is as follows: Figure 1 As shown, it includes a halide electrolyte 2 located in the core and a polymer coating layer 1 disposed on the outer layer. The particle size D50 of the polymer-coated halide electrolyte is 0.1 to 10 μm.

[0061] This invention also provides a method for preparing a solid-state battery, wherein the solid electrolyte separator layer of the solid-state battery is prepared using the polymer-coated halide solid electrolyte described above. The method for preparing the solid-state battery specifically includes the following steps:

[0062] (1) Preparation of negative electrode sheet: The negative electrode material, conductive agent, binder, dispersant and solid electrolyte are mixed and slurried to obtain a negative electrode slurry, which is then coated, dried or calcined to obtain a negative electrode sheet;

[0063] The specific process is as follows: A negative electrode slurry is prepared by mixing the negative electrode material, conductive agent, binder, dispersant, and solid electrolyte. The solid content in the negative electrode slurry is 30-55 wt%, and the concentration of the halide solid electrolyte is 1-30 wt%. The negative electrode slurry is then coated and dried (or calcined) to obtain the negative electrode sheet. The drying or calcination temperature is 50-650℃. The materials used in the preparation of the negative electrode sheet are as follows: the negative electrode material is selected from graphite or silicon-carbon negative electrode materials; the conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene; the binder can be PI, PPS, PADF, PAN, etc., with high-temperature resistant binders preferred; the dispersant is selected from CMC or PVP; the solid electrolyte is a halide solid electrolyte and a non-halide solid electrolyte, with the halide solid electrolyte being Li. a MX b Or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, 0≤c<1. The specific halide electrolyte is selected from Li3InCl6, Li3YCl6, Li3ScCl6, and Li3InBr6. The non-halogen electrolyte is preferably a ceramic solid electrolyte, such as one of LLZO, LLTO, LATP, and LAGP, or a composite electrolyte system of several ceramic solid electrolytes such as LLZO, LLTO, LATP, and LAGP.

[0064] (2) Preparation of solid electrolyte isolation layer: The polymer-coated halide solid electrolyte and non-halogen solid electrolyte are added to an oily solvent to obtain an electrolyte slurry, which is then coated onto the negative electrode sheet in step (1). After standing for a period of time until the electrolyte slurry penetrates into the interior of the negative electrode, the negative electrode sheet coated with a solid electrolyte isolation layer is obtained by drying and compaction.

[0065] The specific process is as follows: A polymer-coated halide solid electrolyte and a non-halide solid electrolyte are added to an oily solvent to obtain an electrolyte slurry. The polymer-coated halide solid electrolyte is prepared using a method for preparing polymer-coated halide solid electrolytes. The non-halide electrolyte is a polymer solid electrolyte and / or a ceramic solid electrolyte. The polymer solid electrolyte is selected from PEO, PVDF-HFP, or PMMA, and the ceramic solid electrolyte is selected from LLZO, LLTO, LATP, LAGP, or a mixed composite electrolyte system. The oily solvent is selected from NMP or tetrahydrofuran. The electrolyte slurry is then coated onto the negative electrode sheet prepared in step (1). After coating, the electrolyte slurry is allowed to penetrate deep into the negative electrode. It is then dried until the surface is no longer sticky (e.g., the drying temperature is controlled at 90–110°C), and then compacted to form a solid electrolyte isolation layer.

[0066] (3) Preparation of positive electrode sheet: The positive electrode material, conductive agent, polymer-coated halide solid electrolyte, non-halogen solid electrolyte, and dispersant are added to an oily solvent and mixed to form a slurry to obtain a positive electrode slurry. Then, the slurry is coated, dried, and compacted to obtain a positive electrode sheet.

[0067] The specific process is as follows: A positive electrode material, a conductive agent, a polymer-coated halide solid electrolyte, a non-halide solid electrolyte, and a dispersant are added to an oily solvent and mixed to form a slurry, thus obtaining a positive electrode slurry. The positive electrode material is selected from lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium manganese oxide. The conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene. The polymer-coated halide solid electrolyte is prepared using a method for preparing polymer-coated halide solid electrolytes. The non-halide solid electrolyte preferably uses a polymer solid electrolyte and / or a ceramic solid electrolyte. The polymer solid electrolyte is selected from PEO, PVDF-HFP, or PMMA. The ceramic solid electrolyte is selected from LLZO, LLTO, LATP, or LAGP, or a composite electrolyte system of several ceramic solid electrolytes such as LLZO, LLTO, LATP, and LAGP. The dispersant is selected from CMC or PVP. The oily solvent is selected from NMP or tetrahydrofuran. The above positive electrode slurry is coated, dried, and compacted to obtain the positive electrode sheet.

[0068] (4) Assembly: The positive electrode sheet and the negative electrode sheet coated with a solid electrolyte isolation layer are assembled into a cell to obtain a solid-state battery.

[0069] The specific process is as follows: Positive electrode sheets and negative electrode sheets coated with a solid electrolyte separator are placed face-to-face and assembled into a cell through stacking or winding; then, the cell is hot-pressed until the polymer in the positive electrode sheet softens, and then dried and packaged to obtain a solid-state battery; alternatively, for pouch-type solid-state batteries, the cells can be dried and packaged first, and then hot-pressed. During the hot-pressing process, the hot-pressing temperature is 35–70℃, and the pressure is 20–30 MPa.

[0070] See the schematic diagram of the solid-state battery obtained above. Figure 2As shown in the figure, in the upper positive electrode, 7 is aluminum foil, 8 is the positive electrode material, and 9 is a halide solid electrolyte; the middle part is the solid electrolyte separator layer 10; in the lower negative electrode, 3 is a polymer-coated halide solid electrolyte, 4 is a non-halide solid electrolyte (ceramic / polymer solid electrolyte), 5 is a binder, 6 is the negative electrode material, and 11 is copper foil. The polymer-coated halide electrolyte 3 in the solid electrolyte separator layer 10 enters the interior of the negative electrode and comes into contact with the negative electrode material 6, the non-halide solid electrolyte 4, and the binder 5, filling the voids formed after the high-temperature firing of the negative electrode. This compensates for the physical contact problem of the ceramic solid electrolyte and the poor room-temperature ion conductivity due to the large amount of polymer electrolyte, effectively solving the physical contact problem and improving the ion conductivity.

[0071] The preparation method of the polymer-coated halide solid electrolyte and solid battery of the present invention will be further described below with specific examples.

[0072] Example 1

[0073] This embodiment provides a method for preparing a polymer-coated halide solid electrolyte, comprising the following steps:

[0074] (a) The polymer PI is dissolved in the oily solvent NMP to form a solution, and the concentration of PI in the solution is 1 wt%.

[0075] (b) The halide solid electrolyte Li3InCl6 is added to the above solution to form a solid electrolyte suspension, wherein the solid content of the halide solid electrolyte Li3InCl6 in the solid electrolyte suspension is 65wt%.

[0076] (c) Spray drying was used, and the drying temperature was controlled at 140°C. After drying, a polymer-coated halide electrolyte with a particle size D50 of 300 nm was obtained.

[0077] Example 2

[0078] This embodiment provides a method for preparing a polymer-coated halide solid electrolyte, comprising the following steps:

[0079] (a) The polymer PVDF-HFP was dissolved in the oily solvent NMP to form a solution, and the concentration of PVDF-HFP in the solution was 5.5 wt%.

[0080] (b) The halide solid electrolyte Li3InCl6 is added to the above solution to form a solid electrolyte suspension, wherein the concentration of the halide solid electrolyte Li3InCl6 in the solid electrolyte suspension is 40 wt%.

[0081] (c) Spray drying was used, and the drying temperature was controlled at 140°C. After drying, a polymer-coated halide electrolyte with a particle size D50 of 10 μm was obtained.

[0082] Example 3

[0083] This embodiment provides a method for preparing a polymer-coated halide solid electrolyte, comprising the following steps:

[0084] (a) The polymer PMMA is dissolved in the oily solvent NMP to form a solution, wherein the concentration of PMMA in the solution is 15 wt%;

[0085] (b) The halide solid electrolyte Li3InCl6 is added to the above solution to form a solid electrolyte suspension, wherein the concentration of the halide solid electrolyte Li3InCl6 in the solid electrolyte suspension is 10 wt%.

[0086] (c) After stirring, the mixture is filtered and dried to obtain a polymer-coated halide electrolyte with a particle size D50 of 3 μm.

[0087] Example 4

[0088] This embodiment provides a method for preparing a solid-state battery, including the following steps:

[0089] (1) First, polymer-coated halide solid electrolyte is prepared: polymer PI is dissolved in oily solvent NMP to form a solution with a concentration of PI of 5.5 wt%; halide solid electrolyte Li3InCl6 is added to the above solution to form a solid electrolyte suspension with a concentration of 40 wt%; spray drying is used with a drying temperature of 140 ℃ to obtain PI-coated Li3InCl6 (polymer-coated halide solid electrolyte) with a particle size D50 of 300 nm.

[0090] (2) A negative electrode slurry was prepared by mixing silicon-carbon anode (anode material), SP (conductive agent), carbon nanotubes (conductive agent), PVP (dispersant), CMC (binder), LATP (ceramic solid electrolyte in solid electrolyte), Li3InCl6 (halide solid electrolyte in solid electrolyte) and pure water. In the negative electrode slurry, the concentration of Li3InCl6 was 20wt% and the solid content was 34wt%. Then, it was coated on a 6μm copper foil at a speed of 2m / min, with an areal density of 3.3mAh / cm². 2 Drying and roasting are carried out on a conveyor belt in a hot air oven at 70–550℃;

[0091] (3) A slurry was prepared by mixing PI-coated Li3InCl6, LLTO (ceramic solid electrolyte), PEO (polymer solid electrolyte), and NMP (oil solvent), with a solid content of 55 wt%. The electrolyte slurry was then coated onto the negative electrode sheet, and a 1.5-minute unheated section was set in the conveyor belt to allow NMP, PEO, and some Li3InCl6 and LLTO to penetrate into the lower layer. The sheet was dried at 90°C until the surface was no longer sticky and compacted to 1.6 g / cm³. 3 Forming a solid electrolyte isolation layer;

[0092] (4) NCM811 (cathode material), SP (conductive agent), carbon nanotubes (conductive agent), PI-coated Li3InCl6, LLTO (ceramic solid electrolyte), PEO (polymer solid electrolyte), and PVP (dispersant) were mixed in NMP (oil-based solvent) to prepare a positive electrode slurry, wherein the solid content of the positive electrode slurry was 62wt%; the slurry was coated on a 12µm aluminum foil with an areal density of 3mAh / cm². 2 Then it is dried and compacted to 3.6 g / cm³. 3 Forming a positive electrode sheet;

[0093] (5) Cut the positive electrode sheet and the negative electrode sheet with solid electrolyte isolation layer, stack them to 4Ah, dry them and put them into an aluminum-plastic film shell for pre-sealing, leaving an exhaust port; perform hot pressing, control the hot pressing temperature at 70℃ and the pressure at 20MPa, exhaust and seal, and complete the solid-state battery preparation.

[0094] Testing revealed that the solid-state battery of this embodiment has a DC internal resistance of 35.2 Ω at room temperature, while the solid-state battery prepared by conventional methods has a DC internal resistance greater than 700 Ω at room temperature. Therefore, it is evident that the ion conduction performance of the solid-state battery of this embodiment is far superior to that of the solid-state battery prepared by conventional methods.

[0095] Example 5

[0096] This embodiment provides a method for preparing a solid-state battery, including the following steps:

[0097] (1) First, polymer-coated halide solid electrolyte is prepared: polymer PVDF-HFP is dissolved in oily solvent NMP to form a solution with a concentration of 3wt%; halide solid electrolyte Li3InCl6 is added to the above solution to form a solid electrolyte suspension, wherein the solid content of halide solid electrolyte Li3InCl6 in the solid electrolyte suspension is 10wt%; spray drying is used, and the drying temperature is controlled at 140℃. After drying, PVDF-HFP-coated Li3InCl6 (polymer-coated halide solid electrolyte) is obtained with a particle size D50 of 100nm.

[0098] (2) A negative electrode slurry was prepared by mixing silicon-carbon anode (anode material), SP (conductive agent), carbon nanotubes (conductive agent), PVP (dispersant), CMC (binder), LATP (ceramic solid electrolyte in solid electrolyte), Li3InCl6 (halide solid electrolyte in solid electrolyte) and pure water. In the negative electrode slurry, the concentration of Li3InCl6 was 20wt% and the solid content was 40wt%. Then, it was coated on a 6μm copper foil at a speed of 2m / min, with an areal density of 3.3mAh / cm². 2 Drying and roasting are carried out on a conveyor belt in a hot air oven at 70-95℃;

[0099] (3) A slurry was prepared by mixing PVDF-HFP-coated Li3InCl6, LLTO (ceramic solid electrolyte), and NMP (oil-based solvent), with a solid content of 55 wt%. The electrolyte slurry was then coated onto the negative electrode sheet, and a 1.5-minute unheated section was set in the conveyor belt to allow NMP, PEO, and some Li3InCl6 and LLTO to penetrate into the lower layer. The sheet was dried at 90°C until the surface was no longer sticky and compacted to 1.6 g / cm³. 3 Forming a solid electrolyte isolation layer;

[0100] (4) NCM811 (cathode material), SP (conductive agent), carbon nanotubes (conductive agent), PI-coated Li3InCl6, LLTO (ceramic solid electrolyte), PEO (polymer solid electrolyte), and PVP (dispersant) were mixed in NMP (oil-based solvent) to prepare a positive electrode slurry, wherein the solid content of the positive electrode slurry was 62 wt%; the slurry was coated on a 12 μm aluminum foil with an areal density of 3 mAh / cm². 2 Then it is dried and compacted to 3.6 g / cm³. 3 Forming a positive electrode sheet;

[0101] (5) The positive electrode sheet and the negative electrode sheet with solid electrolyte isolation layer are cut and stacked to 4Ah. After drying, they are placed in an aluminum-plastic film shell for pre-sealing, and 0.6g of EC solvent and 0.2g of LiTFSI ion electrolyte are injected, leaving an exhaust port. After standing for 12h, hot pressing is performed, and the hot pressing temperature is controlled at 60℃ and the pressure is 20MPa. After exhausting and sealing, the solid-state battery is completed.

[0102] Testing revealed that the solid-state battery of this embodiment has a DC internal resistance of 110Ω at room temperature, while the solid-state battery prepared by conventional methods has a DC internal resistance greater than 700Ω at room temperature. This demonstrates that the ion-conducting performance of the solid-state battery of this embodiment is far superior to that of the solid-state battery prepared by conventional methods.

[0103] Example 6

[0104] This embodiment provides a method for preparing a solid-state battery, including the following steps:

[0105] (1) First, a polymer-coated halide solid electrolyte was prepared: the polymer PVDF-HFP was dissolved in the oily solvent NMP to form a solution with a concentration of 5.5 wt%; the halide solid electrolyte Li3InCl6 was added to the above solution to form a solid electrolyte suspension, wherein the solid content of the halide solid electrolyte Li3InCl6 in the solid electrolyte suspension was 65 wt%; spray drying was carried out and the drying temperature was controlled at 80℃. After drying, PVDF-HFP-coated Li3InCl6 (polymer-coated halide solid electrolyte) was obtained with a particle size D50 of 2.3 μm.

[0106] (2) A negative electrode slurry was prepared by mixing silicon-carbon anode (anode material), SP (conductive agent), carbon nanotubes (conductive agent), PVP (dispersant), CMC (binder), LATP (ceramic solid electrolyte in solid electrolyte), Li3InCl6 (halide solid electrolyte in solid electrolyte) and pure water. In the negative electrode slurry, the concentration of Li3InCl6 was 15wt% and the solid content was 40wt%. Then, it was coated on a 6μm copper foil at a speed of 2m / min, with an areal density of 4.4mAh / cm². 2 Drying and roasting are carried out on a conveyor belt in a hot air oven at 50-85℃.

[0107] (3) A slurry was prepared by mixing PVDF-HFP-coated Li3InCl6, LLTO (ceramic solid electrolyte), and NMP (oil solvent), with a solid content of 55 wt%. The electrolyte slurry was then coated onto the negative electrode sheet, and a 3.0-minute unheated section was set in the conveyor belt to allow NMP, PEO, and some Li3InCl6 and LATP to penetrate into the lower layer. The sheet was then dried at 110°C until the surface was no longer sticky and compacted to 1.6 g / cm³. 3 Forming a solid electrolyte isolation layer;

[0108] (4) NCM811 (cathode material), SP (conductive agent), carbon nanotubes (conductive agent), PI-coated Li3InCl6, LLTO (ceramic solid electrolyte), PEO (polymer solid electrolyte), and PVP (dispersant) were mixed in NMP (oil-based solvent) to prepare a positive electrode slurry, wherein the solid content of the positive electrode slurry was 62 wt%; the slurry was coated on a 12 μm aluminum foil with an areal density of 3 mAh / cm². 2 Then it is dried and compacted to 4.2 g / cm³. 3 Forming a positive electrode sheet;

[0109] (5) The positive electrode sheet and the negative electrode sheet with solid electrolyte isolation layer are cut and stacked to 4Ah. After drying, they are placed in an aluminum-plastic film shell for pre-sealing. 0.6g of EC solvent and 0.2g of LiTFSI ion electrolyte are injected, and an exhaust port is left. After standing for 12h, hot pressing is performed. The hot pressing temperature is controlled at 50℃ and the pressure is 30MPa. After exhausting and sealing, the solid-state battery is completed.

[0110] Testing revealed that the solid-state battery of this embodiment has a DC internal resistance of 241Ω at room temperature, while the solid-state battery prepared by conventional methods has a DC internal resistance greater than 700Ω at room temperature. This demonstrates that the ion-conducting performance of the solid-state battery of this embodiment is far superior to that of the solid-state battery prepared by conventional methods.

[0111] In summary, using polymer-coated halide electrolytes avoids the problems of deliquescence and difficulty in dehydration during storage and use. The solid electrolyte isolation layer formed by the polymer-coated halide electrolyte forms a surface contact on the material by complete dissolution in the negative electrode, while the voids formed after the high-temperature calcination of the negative electrode are filled by the subsequently coated oil-based electrolyte slurry. Therefore, the physical contact problem is effectively solved and the ion conduction capability is improved. The solid electrolyte isolation layer formed by the polymer-coated halide electrolyte, polymer solid electrolyte, and ceramic solid electrolyte takes into account the characteristics of different electrolytes, making up for the physical contact problem of ceramic solid electrolyte and the poor room temperature ion conduction problem when the amount of polymer electrolyte is large.

[0112] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing a polymer-coated halide solid electrolyte, characterized in that, The polymer is dissolved in an oily solvent to form a solution, and then a halide solid electrolyte is added to the solution to form a solid electrolyte suspension. The solid electrolyte suspension is then dried to obtain the polymer-coated halide solid electrolyte. The polymer is selected from one of PI, PPS, PVDF, PVDF-HFP and PMMA; The oily solvent is selected from one of NMP, tetrahydrofuran, ethylene carbonate, and dimethyl carbonate; The halide solid electrolyte is Li a MX b Or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, and 0≤c<1; In the solution, the concentration of the polymer is 1–15 wt%; In the solid electrolyte suspension, the solid content of the halide solid electrolyte is 10-65 wt%. The particle size D50 of the polymer-coated halide solid electrolyte is 0.1–10 μm.

2. The preparation method according to claim 1, characterized in that, The drying method is one of spray drying, vacuum drying, hot air drying, infrared drying, or microwave drying.

3. The preparation method according to claim 2, characterized in that, When the drying method is spray drying, the drying temperature is 80–140°C; and / or The Li a MX b The halide solid electrolyte is selected from one of Li3InCl6, Li3YCl6, Li3ScCl6 or Li3InBr6.

4. A polymer-coated halide solid electrolyte material, characterized in that, The polymer-coated halide solid electrolyte material is prepared by the method for preparing polymer-coated halide solid electrolyte according to any one of claims 1 to 3.

5. A method for preparing a solid-state battery, characterized in that, The solid electrolyte separator of the solid-state battery is prepared using a polymer-coated halide solid electrolyte prepared by the method described in any one of claims 1 to 3.

6. The method for preparing a solid-state battery according to claim 5, characterized in that, The method for preparing the solid-state battery includes the following steps: (1) Preparation of negative electrode sheet: The negative electrode material, conductive agent, binder, dispersant, halide solid electrolyte and non-halide solid electrolyte are mixed and slurried to obtain negative electrode slurry, and then coated, dried or calcined to obtain negative electrode sheet; (2) Preparation of solid electrolyte isolation layer: The polymer-coated halide solid electrolyte and non-halide solid electrolyte are added to an oily solvent to obtain an electrolyte slurry, which is then coated onto the negative electrode sheet in step (1). After the electrolyte slurry penetrates into the interior of the negative electrode, it is dried and compacted to obtain a negative electrode sheet coated with a solid electrolyte isolation layer. (3) Preparation of positive electrode sheet: The positive electrode material, conductive agent, polymer-coated halide solid electrolyte, non-halide solid electrolyte, and dispersant are added to an oily solvent and mixed to form a slurry to obtain a positive electrode slurry. Then, the slurry is coated, dried, and compacted to obtain a positive electrode sheet. (4) Assembly: The positive electrode and the negative electrode coated with a solid electrolyte isolation layer are assembled into a cell to obtain a solid battery.

7. The method for preparing a solid-state battery according to claim 6, characterized in that, In step (1): The negative electrode material is selected from one of graphite and silicon-carbon negative electrode materials; and / or The conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene; and / or The dispersant is selected from CMC, PVP, and / or The halide solid electrolyte is Li a MX b Or Li3Y 1-c In c X6, where M is a metallic element selected from In, Sc, Y, and La, and X is a halogen element, 0≤a≤10, 1≤b≤13, 0≤c<1; and / or The non-halogenated electrolyte is a ceramic solid electrolyte; and / or The drying or calcination temperature is 50–650°C; and / or In the negative electrode slurry, the concentration of the halide solid electrolyte is 1–30 wt%; and / or The ceramic solid electrolyte is selected from one of LLZO, LLTO, LATP, and LAGP.

8. The method for preparing a solid-state battery according to claim 6, characterized in that, In step (2): The non-halogenated electrolyte is a polymer solid electrolyte and / or a ceramic solid electrolyte; and / or The oily solvent is selected from NMP or tetrahydrofuran; and / or The drying temperature is 90–110°C.

9. The method for preparing a solid-state battery according to claim 8, characterized in that, In step (2) and / or step (3): The polymer solid electrolyte is selected from one of PEO, PVDF-HFP, or PMMA; and / or The ceramic solid electrolyte is selected from one of LLZO, LLTO, LATP, or LAGP.

10. The method for preparing a solid-state battery according to claim 6, characterized in that, In step (3): The cathode material is selected from one of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium manganese oxide; and / or The conductive agent is selected from one or more of carbon black, carbon nanotubes, and graphene; and / or The non-halide solid electrolyte is a polymer solid electrolyte and / or a ceramic solid electrolyte; and / or The dispersant is selected from CMC, PVP, and / or The oily solvent is selected from NMP or tetrahydrofuran.

11. A solid-state lithium-ion battery, characterized in that, The solid-state lithium-ion battery is prepared by the method for preparing a solid-state battery according to any one of claims 5 to 10.

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