Oxide solid electrolyte film, preparation method and solid-state battery

Abstract

The invention relates to an oxide solid electrolyte thin film, a preparation method and a solid-state battery, the oxide solid electrolyte thin film comprises a plurality of solid electrolyte units with rigid structures and at least one high-molecular polymer with a flexible structure, and the high-molecular polymer and the solid electrolyte units are the same in thickness. The high-molecular polymer is arranged among the plurality of mutually independent solid electrolyte units and is connected with the plurality of solid electrolyte units to form a large-area oxide solid electrolyte thin film. The oxide solid electrolyte film provided by the invention has the advantages of high solid electrolyte density, good bending characteristic, high ionic conductivity and the like, and can meet the requirements of various use environments.

Description

Technical Field

[0001] The present invention relates to the field of preparation of solid electrolytes for lithium batteries, and in particular to an oxide solid electrolyte film and a preparation method thereof, and a solid-state battery. Background Art

[0002] All-solid-state lithium batteries use solid electrolytes instead of traditional liquid electrolytes. They achieve charging and discharging through the migration of lithium ions between the positive and negative electrodes. They have the advantages of high safety, long life and high energy density, and can maintain good performance after multiple charges and discharges.

[0003] In the preparation process of all-solid-state lithium batteries, the current preparation method of oxide solid electrolyte film is mainly to mix oxide solid electrolyte particles with a binder such as polyvinylidene fluoride, and then form a solid electrolyte film through a casting or pressing process.

[0004] When the oxide solid electrolyte film is prepared by the above method, the oxide solid electrolyte particles are dispersed in the binder, which is a continuous structure, while the oxide solid electrolyte particles are essentially in a discrete state and do not form a continuous solid electrolyte structure, so the lithium ion conductivity is low.

[0005] If the oxide solid electrolyte particles are prepared into a continuous phase in order to improve the lithium ion conductivity, the solid electrolyte will become a brittle material similar to ceramics, resulting in poor bending properties of the solid electrolyte, and the prepared oxide solid electrolyte film will be unable to meet the requirements of high lithium ion conductivity and flexibility at the same time. Summary of the invention

[0006] In order to optimize the density, bending characteristics and preparation process of oxide solid electrolyte film, the purpose of the present invention is to provide an oxide solid electrolyte film and a preparation method, and a solid-state battery.

[0007] The first object of the present application is to provide an oxide solid electrolyte film, which adopts the following technical solution: An oxide solid electrolyte film comprises a plurality of solid electrolyte units with a rigid structure and at least one high molecular polymer with a flexible structure. The high molecular polymer is arranged between a plurality of mutually independent solid electrolyte units and connects the plurality of solid electrolyte units to form a large-area oxide solid electrolyte film.

[0008] By adopting the above technical solution, the oxide solid electrolyte film has good bending properties, supports the winding battery assembly process, reduces production costs and improves energy density.

[0009] The area of ​​a single solid electrolyte unit is between 0.01 and 100 square millimeters, and the thickness of the oxide solid electrolyte film is between 10 and 100 μm.

[0010] By adopting the above technical solution, the independent solid electrolyte unit with a rigid structure is small in area and easy to be arranged, so that the bending characteristics of the oxide solid electrolyte film can be easily controlled.

[0011] The electrolyte material of the solid electrolyte unit includes one or more of garnet type, perovskite type, LISICON type, NASICON type, apatite type and spinel type; The high molecular polymer includes one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin and rubber.

[0012] By adopting the above technical scheme, the selected electrolyte materials have good structural stability, ion conductivity efficiency and a wide electrochemical window, the selected high molecular polymers have good thermal stability, processing performance and electrochemical properties, and the oxide solid electrolyte film prepared by combining one or more of the above materials has good high temperature resistance, resistance to lithium dendrites and mechanical strength.

[0013] The second object of the present application is to provide a method for preparing an oxide solid electrolyte film, which is used to prepare the above-mentioned oxide solid electrolyte film, comprising the following steps: S1, preparing a rigid solid electrolyte sheet with a certain thickness and length and width through ceramic molding and sintering processes; S2, stacking a plurality of the solid electrolyte sheets in a thickness direction with a certain gap, placing at least one high molecular polymer in the gap, and preparing a composite solid electrolyte body; S3, selecting a thickness stacking surface of the composite solid electrolyte body 1, performing a first multi-wire cutting in a direction perpendicular to the stacking direction of the solid electrolyte sheets, and forming a plurality of solid electrolyte strips on the composite solid electrolyte body 1; S4, cleaning the composite solid electrolyte body cut in S3 to remove dirt and waste, and drying it; S5, placing at least one high molecular polymer in the gap formed by cutting in S3, and preparing a second composite solid electrolyte body; S6, performing a second multi-wire cutting on the composite solid electrolyte body 2 in a direction perpendicular to the first multi-wire cutting to obtain an oxide solid electrolyte film; S7. Surface treatment is performed on the oxide solid electrolyte film obtained in S6.

[0014] By adopting the above technical solution, a large-area oxide solid electrolyte film is formed by connecting multiple independent solid electrolyte units by high molecular polymer. The size and spacing of the solid electrolyte units in the oxide solid electrolyte film can be adjusted, which facilitates the regulation of the bending characteristics of the oxide solid electrolyte film.

[0015] In S2, the preparation process of the composite solid electrolyte body 1 is: A high molecular polymer solution is coated on the surface of the solid electrolyte sheet, and after drying to remove the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. After stacking a plurality of the solid electrolyte sheets, hot pressing is performed under vacuum conditions to prepare a composite solid electrolyte body.

[0016] By adopting the above technical solution, under vacuum hot pressing conditions, the solid electrolyte sheets can be quickly combined through the high molecular polymer arranged on the solid electrolyte sheets, thereby improving the preparation efficiency of the composite solid electrolyte body.

[0017] In S2, the preparation process of the composite solid electrolyte body 1 is: An isolation layer is locally arranged on the solid electrolyte sheet, the plurality of solid electrolyte sheets are stacked in the thickness direction to form a gap, a high molecular polymer is arranged in the gap by a vacuum encapsulation process, and a composite solid electrolyte body is prepared.

[0018] By adopting the above technical solution, under the pressure of vacuum potting, the high molecular polymer can be completely filled in the gaps of the solid electrolyte sheet to improve the bonding effect between the solid electrolyte sheet and the high molecular polymer, avoiding the occurrence of stratification or pores in a part of the composite solid electrolyte body.

[0019] In S2, the preparation process of the composite solid electrolyte body 1 is: An isolation layer is locally arranged on the solid electrolyte sheet, the plurality of solid electrolyte sheets are stacked in the thickness direction to form a gap, the stacked solid electrolyte sheets are immersed in a polymer solution, a polymer film is formed on the surface of the solid electrolyte sheet after drying and removing the solvent, a polymer is arranged in the gap by a vacuum potting process, and a composite solid electrolyte body (2) is prepared.

[0020] By adopting the above technical solution, the solid electrolyte sheet is firstly surface treated with a high-viscosity polymer solution to form a thin film structure, which can further improve the bonding effect between the solid electrolyte sheet and the high-molecular polymer.

[0021] In S3, a thickness stacking surface of the composite solid electrolyte body is selected and fixed on a disposable jig, and then the opposite surface of the disposable jig is selected to perform the first multi-wire cutting in a direction perpendicular to the stacking direction of the solid electrolyte sheets.

[0022] By adopting the above technical solution, the disposable jig can maintain the integrity of the composite solid electrolyte body 1 after the first multi-wire cutting, and prevent the composite solid electrolyte body 1 from loosening and affecting subsequent processing.

[0023] In S5, the preparation process of the composite solid electrolyte body 2 is: A high molecular polymer is placed in the gap formed by the first multi-wire cutting through a vacuum potting process, and a composite solid electrolyte body 2 is prepared; By adopting the above technical solution, under the pressure of vacuum encapsulation, the high molecular polymer can have a higher encapsulation efficiency and ensure that the high molecular polymer is completely filled in the gap formed by the first multi-wire cutting, thereby improving the preparation efficiency of the composite solid electrolyte body 2.

[0024] In S5, the preparation process of the composite solid electrolyte body 2 is: The composite solid electrolyte body 1 cleaned with S4 is immersed in a polymer solution, and after drying to remove the solvent, a polymer film is formed on the surface of the cut gap of the composite solid electrolyte body 1, and the polymer is placed in the gap through a vacuum encapsulation process to prepare a composite solid electrolyte body 2.

[0025] By adopting the above technical solution, the setting of the polymer film can improve the bonding effect between the solid electrolyte and the high molecular polymer in the second composite solid electrolyte body.

[0026] The high molecular polymer solution includes one or more of polyimide solution, polyvinylidene fluoride solution, epoxy solution, acrylic solution, silane coupling agent and modified solutions thereof.

[0027] By adopting the above technical scheme, the above material has good viscosity, film-forming properties and electrochemical properties. By surface treating the solid electrolyte sheet with one or more solutions, the bonding force between the solid electrolyte sheet and the polymer can be strengthened, thereby avoiding defects in the composite solid electrolyte body one or the composite solid electrolyte body two.

[0028] In S3, the first multi-wire cutting is performed by diamond wire, and the wire spacing is set to 0.1-3 mm to control the aspect ratio of the solid electrolyte unit; In S6, the second multi-wire cutting is performed by diamond wire cutting, and the wire spacing is set to 10-100 μm to control the thickness of the oxide solid electrolyte film.

[0029] By adopting the above technical scheme, the aspect ratio of the solid electrolyte unit can be regulated by controlling the line spacing of the first multi-wire cutting, so that the bending characteristics of the oxide solid electrolyte film are adjustable, and the oxide solid electrolyte films of different thicknesses can be conveniently processed in batches by controlling the line spacing of the second multi-wire cutting.

[0030] The third purpose of the present application is to provide a solid-state battery, comprising a positive electrode, a negative electrode and an oxide solid electrolyte film prepared by the above method, wherein the oxide solid electrolyte film is arranged between the positive electrode and the negative electrode as a channel for lithium ion transfer.

[0031] By adopting the above technical solution, the solid-state lithium battery using the oxide solid electrolyte film solves the core problems such as interface instability, thermal runaway, and lithium dendrite penetration, thereby improving the battery energy density, safety, and cycle life of the solid-state lithium battery.

[0032] In summary, the beneficial technical effects of the present invention are: 1. The oxide solid electrolyte film prepared in this application has good bending properties, supports the winding battery assembly process, reduces production costs, and has the advantages of high solid electrolyte density and high ion conductivity, and has good conductivity efficiency in a variety of use environments; 2. The first multi-wire cutting makes it easy to adjust the aspect ratio of the independent solid electrolyte unit, and the oxide solid electrolyte film is easy to adjust during the second multi-wire cutting, so the bending characteristics of the prepared oxide solid electrolyte film are easy to adjust, which is convenient for adjusting the bending characteristics of the oxide solid electrolyte film in different directions according to the application requirements of the oxide solid electrolyte film; 3. In the oxide solid electrolyte film prepared in the present application, there is a good bonding effect between the solid electrolyte unit and the high molecular polymer, which can effectively prevent the solid electrolyte unit from falling off and ensure that the oxide solid electrolyte film has good reliability at different thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the oxide solid electrolyte film in Example 1.

[0034] Figure 2 It is a schematic diagram of the first multi-wire cutting in Example 1.

[0035] Figure 3 Schematic diagram of the second multi-wire cutting in Example 1.

[0036] Figure 4 It is a schematic diagram of the structure of the oxide solid electrolyte film in Example 2.

[0037] Figure 5 It is a schematic diagram of the structure of the oxide solid electrolyte film in Example 3.

[0038] In the figure, 1. solid electrolyte unit, 2. composite solid electrolyte body 1, 3. composite solid electrolyte body 2, 4. disposable fixture. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0040] The embodiments of the present application disclose an oxide solid electrolyte film and a preparation method thereof, and a solid-state battery.

[0041] Example 1: Reference Figure 1-3 , a method for preparing an oxide solid electrolyte film, comprising the following steps: S1, preparing a rigid solid electrolyte sheet with a certain thickness and length and width through ceramic molding and sintering processes; S2, stacking a plurality of solid electrolyte sheets in a thickness direction according to a certain gap, that is, stacking a plurality of solid electrolyte sheets along the X direction, placing at least one high molecular polymer in the gap, and preparing a composite solid electrolyte body 2; S3, selecting a thickness stacking surface of the composite solid electrolyte body 2, performing the first multi-wire cutting in the direction perpendicular to the stacking direction of the solid electrolyte sheets, that is, performing the first multi-wire cutting along the Y direction, to form a plurality of solid electrolyte strips on the composite solid electrolyte body 2; S4, cleaning the composite solid electrolyte body 2 cut in S3 to remove dirt and waste, and drying it; S5, placing at least one high molecular polymer in the gap formed by cutting in S3, and preparing a composite solid electrolyte body 23; S6, performing a second multi-wire cutting on the composite solid electrolyte body 23 in a direction perpendicular to the first multi-wire cutting, that is, performing a second multi-wire cutting along the Z direction, to obtain an oxide solid electrolyte film; S7. Surface treatment is performed on the oxide solid electrolyte film obtained in S6.

[0042] The oxide solid electrolyte film prepared by S1-S7 includes multiple solid electrolyte units 1 with a rigid structure and at least one polymer with a flexible structure. The polymer has the same thickness as the solid electrolyte unit 1. The polymer is arranged between multiple independent solid electrolyte units 1, and multiple solid electrolyte units 1 are connected to form a large-area oxide solid electrolyte film. The area of ​​a single solid electrolyte unit 1 in the oxide solid electrolyte film is 0.01-100 square millimeters, and the thickness of the oxide solid electrolyte film is between 10-100μm, so that the oxide solid electrolyte film has the advantages of high solid electrolyte density, good bending properties, high ionic conductivity, etc.

[0043] When the oxide solid electrolyte film is specifically applied to a solid-state battery, the oxide solid electrolyte film is arranged between the positive electrode and the negative electrode of the battery, and the two side surfaces of the oxide solid electrolyte film are in surface contact with the positive electrode and the negative electrode respectively to serve as a channel for lithium ion transfer.

[0044] The electrolyte material of the solid electrolyte unit 1 includes one or more of garnet type, perovskite type, LISICON type (lithium superion conductor or lithium ion conductor skeleton structure), NASICON type (sodium superion conductor or sodium ion conductor skeleton structure), apatite type, spinel type and amorphous oxide. In the specific implementation process, lithium silicon zirconium phosphate with LISICON type is selected as the solid electrolyte, polyvinyl butyral is selected as the binder, dibutyl phthalate is used as the plasticizer, modified fish oil is used as the dispersant, and a mixture of ethanol and butanone is used as the solvent to prepare the electrolyte slurry. In the preparation process, it has the advantages of low production cost and high environmental stability, does not require strict inert atmosphere protection, reduces the difficulty and cost of the production process, and the prepared solid electrolyte sheet has the advantages of high ionic conductivity, excellent mechanical strength, strong compatibility, etc.

[0045] The high molecular polymer includes one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin and rubber. In the specific use process, modified polyimide is selected to introduce ether bonds and sulfone groups into the molecular structure of the modified polyimide to enhance the flexibility and polarity of the high molecular polymer, thereby enhancing the bending properties of the oxide solid electrolyte film.

[0046] In the specific implementation of S1, first, the electrolyte slurry is cast into shape through a casting process to prepare a cast film with a thickness of 0.1-1.5 mm. Then, the cast film is punched out to obtain square diaphragms of uniform size. After low-temperature debinding and high-temperature firing, the square diaphragms are subjected to rigid solid electrolyte sheets of uniform thickness.

[0047] In this embodiment, the prepared solid electrolyte sheet is a square sheet with a thickness of 0.5 mm and a length and width of 120 mm, and the thickness of the solid electrolyte sheet is the width of a single solid electrolyte unit 1 in the oxide solid electrolyte film.

[0048] In another embodiment, in the process of preparing rigid solid electrolyte sheets, the film rolling process can be used to replace the casting process to prepare a raw porcelain film with a thickness of 0.2-5 mm. Afterwards, the rigid solid electrolyte sheet is obtained by punching the raw porcelain film, debinding at low temperature and firing at high temperature. At the same time, the film rolling process can be used in conjunction with the casting process, such as first casting and coating the electrolyte slurry, and then rolling and compacting, so as to improve the strength of the square membrane during the punching process.

[0049] In the specific implementation of S2, a 20% concentration of modified polyimide solution is first coated on one surface of the solid electrolyte sheet, and after drying and removing the solvent, a 2-5 μm thin film is formed on the surface of the solid electrolyte sheet. Thereafter, the solid electrolyte sheet is turned over and the other surface is subjected to the same treatment.

[0050] After surface treatment with a 20% modified polyimide solution, a 30% polyimide solution is first coated on one surface of the solid electrolyte sheet. After drying and removing the solvent, a 25-30μm film is formed on the surface. The other surface is flipped over and the same treatment is performed to form a polymer film on both sides of the solid electrolyte sheet, thereby improving the high temperature resistance, lithium dendrite resistance and mechanical strength of the oxide solid electrolyte film. The solid-state lithium battery using the oxide solid electrolyte film solves the core problems of interface instability, thermal runaway, lithium dendrite penetration, etc., thereby improving the battery energy density, safety and cycle life of the solid-state lithium battery.

[0051] A plurality of solid electrolyte sheets are laid flat or stacked vertically, and the stacked solid electrolyte sheets are placed on a curing tool. In this embodiment, a plurality of solid electrolyte sheets are stacked vertically along the X direction. In order to prevent the solid electrolyte sheets from being loose, a clamping force is provided on the curing tool for fixing. After that, the stacked solid electrolyte sheets are placed in a vacuum device, and the temperature is raised to 250-400°C under vacuum conditions and kept warm for 30 minutes. At this temperature, polyimide still has a high viscosity, which can enhance the bonding effect between the solid electrolyte sheet and the polyimide. Then, gas is introduced and the gas pressure is increased to 0.1-2MPa, and hot pressing is performed to prepare a composite solid electrolyte body 2.

[0052] In order to enhance the bonding effect between the high molecular polymer and the solid electrolyte sheet, the surface of the solid electrolyte sheet may be treated before applying the modified polyimide solution.

[0053] In another embodiment, a layer of inorganic slurry is first coated on the surface of the solid electrolyte sheet, dried and then sintered to form a micro-nano roughened structure on the surface of the solid electrolyte sheet to enhance the bonding force with the high molecular polymer.

[0054] In another embodiment, the solid electrolyte sheet is immersed in a silane coupling agent solution, and after drying to remove the solvent, active groups are formed on the surface of the solid electrolyte sheet to strengthen the bonding force with the high molecular polymer.

[0055] When implementing S3, refer to Figure 2 , select a thickness stacking surface of the composite solid electrolyte body 2, and perform the first multi-wire cutting along the Y direction. In the specific implementation process, the first multi-wire cutting uses a diamond wire with a diameter of 0.12mm, and the wire spacing is set to 1mm. After the first multi-wire cutting, multiple gaps with a width of about 0.15mm will be formed on the composite solid electrolyte body 2. At the same time, a single solid electrolyte sheet is cut into multiple solid electrolyte strips with a cross-section of 0.5*1mm, and the cross-sectional size is the size of a single solid electrolyte unit 1 in the oxide solid electrolyte film obtained by S6.

[0056] In the specific operation process, in order to maintain the integrity of the composite solid electrolyte body 2 after the first multi-wire cutting and prevent the composite solid electrolyte body 2 from loosening and affecting subsequent processing, the composite solid electrolyte body 2 is not completely cut through during the first multi-wire cutting.

[0057] In order to reduce the complexity of subsequent processes, before performing the first multi-wire cutting, a thickness stacking surface of the composite solid electrolyte body 2 is first bonded and fixed on the disposable jig 4, and then the opposite surface of the disposable jig 4 is selected to perform the first multi-wire cutting along the Y direction. During the first multi-wire cutting, the composite solid electrolyte body 2 can be completely cut through, thereby ensuring the integrity of the composite solid electrolyte body 2 while reducing material waste.

[0058] In the subsequent process, the disposable jig 4 can be cut off before executing S6 or when performing the second multi-wire cutting to facilitate the preparation of the oxide solid electrolyte film.

[0059] When S4 is specifically implemented, the composite solid electrolyte body 2 is cleaned with ultrasonic cleaning equipment to remove dirt and waste generated during the first multi-wire cutting process, and then placed in a blast drying oven for drying to facilitate processing of the cut surface of the composite solid electrolyte body 2.

[0060] When S5 is specifically implemented, the cutting slit of the composite solid electrolyte body 2 is set upward, and then the composite solid electrolyte body 2 is placed in a vacuum potting machine. After vacuuming, the solid electrolyte body 1 is heated to 250-380°C, and then a polyimide melt at 270-400°C is potted on the upper surface of the solid electrolyte body. Since the cutting slit of the composite solid electrolyte body 2 is tiny, the molten polyimide melt cannot flow naturally into the cutting slit, and the polyimide melt will gradually accumulate on the upper surface of the solid electrolyte body 1. When the cutting slit on the upper surface of the solid electrolyte body 1 is completely covered by the polyimide melt, pressurized gas is introduced into the vacuum potting machine. Under the action of gas pressure, the polyimide melt is gradually pressed into the cutting slit of the composite solid electrolyte body 2. After continuing to keep warm for 0.5-1h, it is cooled to room temperature according to the set cooling system. After the polyimide melt is cooled, the composite solid electrolyte body 2 3 is obtained.

[0061] In another embodiment, in order to improve the bonding effect between the composite solid electrolyte body 2 and the polyimide melt, before the composite solid electrolyte body 2 is placed in the vacuum sealing machine, the composite solid electrolyte body 2 after the first multi-wire cutting is immersed in a silane coupling agent, and the silane coupling agent is used to treat the surface of the solid electrolyte produced by the first multi-wire cutting to improve the adhesion between the composite solid electrolyte body 2 and the polyimide, thereby avoiding the problem of separation of a single solid electrolyte unit 1 on the formed oxide solid electrolyte film.

[0062] When implementing S6, refer to Figure 3 , a second multi-wire cutting is performed on the composite solid electrolyte body 23 along the Z direction to obtain an oxide solid electrolyte film with a thickness of 10-100 μm. In the specific implementation process, a tungsten diamond wire with a diameter of 28 μm is selected for the second multi-wire cutting, and the wire spacing is set to 30 μm. After cutting, multiple oxide solid electrolyte films with a thickness of 30 μm are obtained.

[0063] When S7 is specifically implemented, the cut oxide solid electrolyte film is cleaned and dried to obtain a finished oxide solid electrolyte film.

[0064] In the specific implementation process, the multi-wire cutting marks are further eliminated by grinding or polishing to improve the surface roughness of the oxide solid electrolyte film.

[0065] In one embodiment, the thickness of the oxide solid electrolyte film is further reduced by grinding or polishing.

[0066] Reference Figure 1In this embodiment, a plurality of oxide solid electrolyte films with a thickness of 30 μm can be obtained, wherein the size of a single solid electrolyte unit 1 is 0.5*1 mm. The oxide solid electrolyte film has the advantages of high solid electrolyte density, good bending properties, and high ionic conductivity.

[0067] Embodiment 2: A method for preparing an oxide solid electrolyte film. The difference between this embodiment and embodiment 1 is that: In the specific implementation of S1, a solid electrolyte square sheet with a thickness of 0.3 mm and a length and width of 120 mm is prepared by a tape casting process.

[0068] In the specific implementation of S2, an isolation layer is locally provided on the solid electrolyte sheet, a plurality of solid electrolyte sheets are stacked along the X direction to form a gap, a high molecular polymer is provided in the gap by a vacuum potting process, and a composite solid electrolyte body 2 is prepared. In the specific implementation process, by controlling the thickness of the isolation layer, the stacking gap of the solid electrolyte sheets can be uniformly controlled, thereby improving the controllability of the spacing between the solid electrolyte units 1 in the prepared oxide solid electrolyte film.

[0069] In the specific implementation process, two opposite edges are selected on one side of the solid electrolyte sheet, and an isolation film with a thickness of 0.1 mm is locally pasted along the edge of the solid electrolyte sheet. Then, multiple solid electrolyte sheets are stacked to form a uniform gap.

[0070] In the further implementation process, a clamp is used to clamp and fix the stacked multiple solid electrolyte sheets to form a solid electrolyte stack, and the solid electrolyte stack is placed in a potting tool so that the gap of the solid electrolyte stack is set upward. After that, the solid electrolyte stack is placed in a vacuum potting machine through the potting tool. After vacuuming, the solid electrolyte stack is heated to 250-380°C, and then, a polyimide melt at 270-400°C is potted on the upper surface of the solid electrolyte stack. Then, pressurized gas is introduced, and under the action of gas pressure, the polyimide melt is pressed into the gap between the solid electrolyte sheets. After that, the temperature is kept between 250-380°C for 0.5-1h, and cooled to room temperature according to the set cooling system to form a composite solid electrolyte body-2.

[0071] In another embodiment, in order to improve the bonding effect between polyimide and solid electrolyte sheet, before the solid electrolyte stack is placed in the potting tool, the solid electrolyte stack is first immersed in a silane coupling agent solution. After drying and removing the solvent, active groups are formed on the surface of the solid electrolyte sheet to strengthen the bonding force between the solid electrolyte sheet and the polyimide.

[0072] When S3 is specifically implemented, a thickness stacking surface of the composite solid electrolyte body 2 is first bonded and fixed on the disposable fixture 4, and then the opposite surface of the disposable fixture 4 is selected to perform the first multi-wire cutting along the Y direction. In the specific implementation process, the first multi-wire cutting uses a diamond wire with a diameter of 0.12 mm, and the wire spacing is set to 2 mm. After the first multi-wire cutting, a plurality of gaps with a width of about 0.15 mm will be formed on the composite solid electrolyte body 2, and at the same time, a single solid electrolyte sheet is cut into a plurality of solid electrolyte strips with a cross section of 0.3*2 mm and a length of 120 mm.

[0073] In the further implementation process, S4 is performed according to Example 1 to process the cut composite solid electrolyte body 2.

[0074] In the specific implementation of S5, before the composite solid electrolyte body 2 is placed in a vacuum sealing machine, the solid electrolyte body 1 is first immersed in a modified PI solution. After drying and removing the solvent, a 2-5 μm modified polyimide film is formed on the surface of the solid electrolyte produced by the first multi-wire cutting. While improving the bonding effect between the composite solid electrolyte body 2 and the polyimide sol, the bending properties of the oxide solid electrolyte film can be further improved.

[0075] In the further implementation process, S6 and S7 are performed according to Example 1 to prepare an oxide solid electrolyte film.

[0076] Reference Figure 2 In this embodiment, a plurality of oxide solid electrolyte films with a thickness of 30 μm can be obtained, wherein the size of a single solid electrolyte unit 1 is 0.3*2 mm, and the independent solid electrolyte unit 1 has high flexibility in the direction in which the width of 0.3 mm is set, and can be curled into a columnar shape along the width direction of the solid electrolyte unit 1, and can be used for solid-state batteries with a curling design.

[0077] Embodiment 3: A method for preparing an oxide solid electrolyte film. The difference between this embodiment and embodiment 2 is that: In the specific implementation of S1, a solid electrolyte square sheet with a thickness of 1 mm and a length and width of 120 mm is prepared by a tape casting process.

[0078] When S2 is specifically implemented, two opposite edges are selected on one side of the solid electrolyte sheet, and an isolation film with a thickness of 0.15 mm is locally pasted along the edge of the solid electrolyte sheet. Then, multiple solid electrolyte sheets are stacked along the X direction to form a uniform gap.

[0079] In this embodiment, a plurality of stacked solid electrolyte sheets are clamped and fixed by a clamp to form a solid electrolyte stack, and the solid electrolyte stack is immersed in a modified polyimide solution. After drying and removing the solvent, a 2-5 μm modified polyimide film is formed on the surface of the solid electrolyte sheet to improve the bending properties of the oxide solid electrolyte film after forming, as well as the bonding effect between the solid electrolyte sheet and the polyimide melt.

[0080] In the further implementation process, the solid electrolyte stack is placed in a potting tool so that the gap of the solid electrolyte stack is set upward. After that, the solid electrolyte stack is placed in a vacuum potting machine through the potting tool. After vacuuming, the solid electrolyte stack is heated to 250-380°C. Then, a polyimide melt at 270-400°C is potted on the upper surface of the solid electrolyte stack. Then, pressurized gas is introduced. Under the action of gas pressure, the polyimide melt is pressed into the gap between the solid electrolyte sheets. After that, the temperature is kept between 250-380°C for 0.5-1h. After cooling to room temperature according to the set cooling system, a composite solid electrolyte body 2 is formed.

[0081] When S3 is implemented specifically, the first multi-wire cutting uses a diamond wire with a diameter of 0.12 mm, and the wire spacing is set to 1 mm. After the first multi-wire cutting, a plurality of gaps with a width of about 0.15 mm will be formed on the composite solid electrolyte body 2. At the same time, a single solid electrolyte sheet is cut into a plurality of solid electrolyte strips with a cross-section of 1*1 mm and a length of 120 mm.

[0082] In the further implementation process, S4-S7 are performed according to Example 2 to prepare an oxide solid electrolyte film.

[0083] Reference Figure 3 In this embodiment, a plurality of oxide solid electrolyte films with a thickness of 30 μm can be obtained, wherein the size of a single solid electrolyte unit 1 is 1*1 mm, and independent solid electrolyte units 1 are evenly distributed with a uniform size of 1*1 mm, and there is a fixed gap of 0.15 mm between adjacent solid electrolyte units 1, and the same bending characteristics are exhibited in two directions perpendicular to each other. Compared with Example 2, this arrangement can further reduce the area proportion of the polymer in the oxide solid electrolyte film and improve the ionic conductivity of the film.

[0084] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An oxide solid electrolyte film, characterized in that: The invention comprises a plurality of solid electrolyte units (1) having a rigid structure and at least one high molecular polymer having a flexible structure, wherein the high molecular polymer is arranged between the plurality of mutually independent solid electrolyte units (1) and connects the plurality of solid electrolyte units (1) to form a large-area oxide solid electrolyte film.

2. The oxide solid electrolyte film according to claim 1, characterized in that: The surface area of ​​a single solid electrolyte unit (1) is between 0.01 and 100 square millimeters, and the thickness of the oxide solid electrolyte film is between 10 and 100 μm.

3. The oxide solid electrolyte film according to claim 1, characterized in that: The electrolyte material of the solid electrolyte unit (1) includes one or more of garnet type, perovskite type, LISICON type, NASICON type, apatite type and spinel type; The high molecular polymer includes one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin and rubber.

4. A method for preparing an oxide solid electrolyte film, for preparing the oxide solid electrolyte film according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, preparing a rigid solid electrolyte sheet with a certain thickness and length and width through ceramic molding and sintering processes; S2, stacking a plurality of the solid electrolyte sheets in a thickness direction with a certain gap, placing at least one high molecular polymer in the gap, and preparing a composite solid electrolyte body (2); S3, selecting a thickness stacking surface of the composite solid electrolyte body (2), performing a first multi-wire cutting in a direction perpendicular to the stacking direction of the solid electrolyte sheets, and forming a plurality of solid electrolyte strips on the composite solid electrolyte body (2); S4, cleaning the composite solid electrolyte body 1 (2) cut in S3 to remove dirt and waste, and drying it; S5, placing at least one high molecular polymer in the gap formed by cutting in S3, and preparing a composite solid electrolyte body 2 (3); S6, performing a second multi-wire cutting on the composite solid electrolyte body 2 (3) in a direction perpendicular to the first multi-wire cutting to obtain an oxide solid electrolyte film; S7. Surface treatment is performed on the oxide solid electrolyte film obtained in S6.

5. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S2, the preparation process of the composite solid electrolyte body 1 (2) is: A high molecular polymer solution is coated on the surface of the solid electrolyte sheet, and after drying to remove the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. After stacking a plurality of the solid electrolyte sheets, hot pressing is performed under vacuum conditions to prepare a composite solid electrolyte body (2).

6. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S2, the preparation process of the composite solid electrolyte body 1 (2) is: An isolation layer is locally arranged on the solid electrolyte sheet, the plurality of solid electrolyte sheets are stacked in the thickness direction to form a gap, a high molecular polymer is arranged in the gap by a vacuum encapsulation process, and a composite solid electrolyte body (2) is prepared.

7. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S2, the preparation process of the composite solid electrolyte body 1 (2) is: An isolation layer is locally arranged on the solid electrolyte sheet, the plurality of solid electrolyte sheets are stacked in the thickness direction to form a gap, the stacked solid electrolyte sheets are immersed in a polymer solution, a polymer film is formed on the surface of the solid electrolyte sheet after drying and removing the solvent, a polymer is arranged in the gap by a vacuum potting process, and a composite solid electrolyte body (2) is prepared.

8. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S3, a thickness stacking surface of the composite solid electrolyte body (2) is selected and fixed on a disposable jig (4), and then the opposite surface of the disposable jig (4) is selected to perform a first multi-wire cutting in a direction perpendicular to the stacking direction of the solid electrolyte sheets.

9. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S5, the preparation process of the composite solid electrolyte body 2 (3) includes: A high molecular polymer is placed in the gap formed by the first multi-wire cutting through a vacuum encapsulation process, and a composite solid electrolyte body 2 (3) is prepared.

10. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S5, the preparation process of the composite solid electrolyte body 2 (3) is: The composite solid electrolyte body (2) cleaned with S4 is immersed in a polymer solution, and after drying to remove the solvent, a polymer film is formed on the surface of the cut slit of the composite solid electrolyte body (2), and the polymer is placed in the slit by a vacuum encapsulation process to prepare a composite solid electrolyte body (3).

11. The method for preparing an oxide solid electrolyte film according to claim 5, 7 or 10, characterized in that: The high molecular polymer solution includes one or more of polyimide solution, polyvinylidene fluoride solution, epoxy solution, acrylic solution, silane coupling agent and modified solutions thereof.

12. The method for preparing an oxide solid electrolyte film according to claim 4, characterized in that: In S3, the first multi-wire cutting is performed by diamond wire cutting, and the wire spacing is set to 0.1-3 mm to control the aspect ratio of the solid electrolyte unit (1); In S6, the second multi-wire cutting is performed by diamond wire cutting, and the wire spacing is set to 10-100 μm to control the thickness of the oxide solid electrolyte film.

13. A solid-state battery, characterized in that: It comprises a positive electrode, a negative electrode and the oxide solid electrolyte film according to any one of claims 1 to 3, wherein the oxide solid electrolyte film is arranged between the positive electrode and the negative electrode as a channel for lithium ion transfer.

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