An oxide solid electrolyte thin film and a preparation method, and a solid-state battery

Abstract

This invention relates to an oxide solid electrolyte film and its preparation method, as well as a solid-state battery. The film comprises multiple solid electrolyte units with rigid structures and at least one polymer with a flexible structure. The polymer has the same thickness as the solid electrolyte units and is disposed between the multiple independent solid electrolyte units, connecting them to form a large-area oxide solid electrolyte film. The oxide solid electrolyte film of this invention has advantages such as high solid electrolyte density, good bending characteristics, and high ionic conductivity, making it adaptable to various application environments.

Description

Technical Field

[0001] This invention relates to the field of lithium battery solid electrolyte preparation, and in particular to an oxide solid electrolyte thin film and its preparation method, and a solid battery. Background Technology

[0002] All-solid-state lithium batteries replace traditional liquid electrolytes with solid electrolytes. They achieve charging and discharging through the migration of lithium ions between the positive and negative electrodes, and have advantages such as high safety, long life and high energy density. They can still maintain good performance after multiple charge and discharge cycles.

[0003] In the fabrication process of all-solid-state lithium batteries, the current main method for preparing oxide solid electrolyte films is to mix oxide solid electrolyte particles with a binder similar to polyvinylidene fluoride, and then form a solid electrolyte film through casting or pressing processes.

[0004] When preparing oxide solid electrolyte films using the above methods, the oxide solid electrolyte particles are dispersed in the binder. The binder has a continuous structure, while the oxide solid electrolyte particles are essentially in a discrete state and do not form a continuous solid electrolyte structure. Therefore, the lithium-ion conductivity is low.

[0005] If oxide solid electrolyte particles are prepared as a continuous phase in order to improve lithium-ion conductivity, the solid electrolyte will become a brittle material similar to ceramic, resulting in poor bending characteristics of the solid electrolyte. Consequently, the prepared oxide solid electrolyte film cannot simultaneously meet the requirements of high lithium-ion conductivity and flexibility. Summary of the Invention

[0006] In order to optimize the density, bending characteristics and preparation process of oxide solid electrolyte films, the present invention aims to provide an oxide solid electrolyte film and its preparation method, as well as a solid battery.

[0007] The primary objective of this application is to provide an oxide solid electrolyte thin film, employing the following technical solution:

[0008] An oxide solid electrolyte film includes a plurality of solid electrolyte units with rigid structures and at least one polymer with a flexible structure. The polymer is disposed between the plurality of independent solid electrolyte units and connects the plurality of solid electrolyte units to form a large-area oxide solid electrolyte film.

[0009] By adopting the above technical solutions, oxide solid electrolyte films have good bending characteristics, supporting roll-to-roll battery assembly processes, reducing production costs and increasing energy density.

[0010] 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.

[0011] By adopting the above technical solution, the bending characteristics of the oxide solid electrolyte film can be easily controlled because the independent solid electrolyte unit with rigid structure has a small area and is easy to set.

[0012] The electrolyte material of the solid electrolyte unit includes one or more of the following types: garnet, perovskite, LISICON, NASICON, apatite, and spinel.

[0013] The polymer includes one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin, and rubber.

[0014] By adopting the above technical solutions, the selected electrolyte materials all have good structural stability, ionic conductivity and a wide electrochemical window, and the selected polymers all have good thermal stability, processing performance and electrochemical performance. The oxide solid electrolyte film prepared by combining one or more of the above materials has good high temperature resistance, lithium dendrite resistance and mechanical strength.

[0015] The second objective of this application is to provide a method for preparing an oxide solid electrolyte film, comprising the following steps:

[0016] S1. Rigid solid electrolyte sheets with a certain thickness and length and width dimensions are prepared by ceramic forming and sintering process;

[0017] S2. Stack multiple solid electrolyte sheets in the thickness direction with a certain gap, and place at least one polymer in the gap to prepare a composite solid electrolyte body.

[0018] S3. Select a thickness stacking surface of the composite solid electrolyte body one, and perform a first multi-line cut in the direction perpendicular to the stacking of solid electrolyte sheets to form multiple solid electrolyte strips on the composite solid electrolyte body one.

[0019] S4. Clean the composite solid electrolyte body after S3 cutting to remove dirt and waste, and then dry it.

[0020] S5. Place at least one polymer into the slit formed by cutting in S3, and prepare a composite solid electrolyte body II.

[0021] S6. Perform a second multi-line cut on the composite solid electrolyte body II in a direction perpendicular to the first multi-line cut to obtain an oxide solid electrolyte film.

[0022] S7. Perform surface treatment on the oxide solid electrolyte film obtained in S6.

[0023] By adopting the above technical solution, a large-area oxide solid electrolyte film is formed by connecting multiple independent solid electrolyte units with polymer. The size and spacing of the solid electrolyte units in the oxide solid electrolyte film can be adjusted, which facilitates the control of the bending characteristics of the oxide solid electrolyte film.

[0024] In S2, the preparation process of the composite solid electrolyte is as follows:

[0025] A polymer solution is coated on the surface of the solid electrolyte sheet. After drying and removing the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. Multiple solid electrolyte sheets are stacked and hot-pressed under vacuum conditions to prepare a composite solid electrolyte body.

[0026] By adopting the above technical solution, under vacuum hot pressing conditions, the solid electrolyte sheet can be rapidly combined by a polymer disposed on the solid electrolyte sheet, thereby improving the preparation efficiency of the composite solid electrolyte body.

[0027] In S2, the preparation process of the composite solid electrolyte is as follows:

[0028] An isolation layer is locally formed on the solid electrolyte sheet. The multiple solid electrolyte sheets are stacked in the thickness direction to form gaps. A polymer is placed in the gaps by a vacuum potting process to prepare a composite solid electrolyte body.

[0029] By adopting the above technical solution, under the pressure of vacuum potting, the polymer can be completely filled in the gaps of the solid electrolyte sheet, thereby improving the bonding effect between the solid electrolyte sheet and the polymer and avoiding the delamination or pores in a local area of ​​the composite solid electrolyte.

[0030] In S2, the preparation process of the composite solid electrolyte is as follows:

[0031] An isolation layer is locally provided on the solid electrolyte sheet, the multiple solid electrolyte sheets are stacked in the thickness direction to form gaps, the stacked solid electrolyte sheets are immersed in a polymer solution, and after drying and removing the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. The polymer is placed in the gaps by a vacuum potting process, and a composite solid electrolyte body is prepared (2).

[0032] By adopting the above technical solution, the solid electrolyte sheet is first surface-treated with a highly viscous polymer solution to form a thin film structure, which can further improve the bonding effect between the solid electrolyte sheet and the polymer.

[0033] In S3, a thickness stacking surface of the composite solid electrolyte is selected and fixed on a disposable fixture. Then, the opposite surface of the disposable fixture is selected to perform the first multi-line cut in the direction perpendicular to the stacking of the solid electrolyte sheets.

[0034] By adopting the above technical solution, the disposable fixture can maintain the integrity of the composite solid electrolyte body after the first multi-wire cutting, and avoid the composite solid electrolyte body from becoming loose and affecting subsequent processing.

[0035] In S5, the preparation process of the second composite solid electrolyte is as follows:

[0036] A high-molecular polymer was placed into the gap formed by the first multi-wire cutting using a vacuum potting process, and a composite solid electrolyte body II was prepared.

[0037] By adopting the above technical solution, under the pressure of vacuum potting, the polymer can have a high potting efficiency and ensure that the 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 II.

[0038] In S5, the preparation process of the second composite solid electrolyte is as follows:

[0039] After cleaning with S4, the first composite solid electrolyte body was immersed in a polymer solution. After drying and removing the solvent, a polymer film was formed on the surface of the cut slit of the first composite solid electrolyte body. The polymer was then placed into the slit through a vacuum potting process to prepare the second composite solid electrolyte body.

[0040] By adopting the above technical solution, the polymer film can improve the bonding effect between the solid electrolyte and the polymer in the composite solid electrolyte body II.

[0041] The polymer solution includes one or more of the following: polyimide solution, polyvinylidene fluoride solution, epoxy solution, acrylic solution, silane coupling agent, and modified solution thereof.

[0042] By adopting the above technical solutions, the above materials have good viscosity, film-forming properties and electrochemical properties. By surface-treating the solid electrolyte sheet with one or more of the solutions, the adhesion between the solid electrolyte sheet and the polymer can be strengthened, and defects in composite solid electrolyte body one or composite solid electrolyte body two can be avoided.

[0043] In S3, the first multi-wire cutting is performed with diamond wire, and the wire spacing is set to 0.1-3mm to control the aspect ratio of the solid electrolyte unit;

[0044] In S6, the second multi-wire cutting is performed using diamond wire, with the wire spacing set to 10-100μm to control the thickness of the oxide solid electrolyte film.

[0045] By adopting the above technical solution, the aspect ratio of the solid electrolyte unit can be adjusted by controlling the line spacing of the first multi-wire cutting, making the bending characteristics of the oxide solid electrolyte film adjustable. By controlling the line spacing of the second multi-wire cutting, it is convenient to mass-produce oxide solid electrolyte films of different thicknesses.

[0046] The third objective of this application is to provide a solid-state battery, including a positive electrode, a negative electrode, and an oxide solid electrolyte film prepared by the above method, wherein the oxide solid electrolyte film is disposed between the positive electrode and the negative electrode as a channel for lithium-ion transfer.

[0047] By adopting the above technical solution, the solid-state lithium battery using this 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.

[0048] In summary, the beneficial technical effects of the present invention are as follows:

[0049] 1. The oxide solid electrolyte film prepared in this application has good bending characteristics, supports the roll-up battery assembly process, reduces production costs, and has the advantages of high density and high ionic conductivity of solid electrolytes, and has good conductivity in a variety of usage environments.

[0050] 2. The first multi-wire cutting makes it easy to control the aspect ratio of the independent solid electrolyte unit. The second multi-wire cutting makes it easy to control the oxide solid electrolyte film. Therefore, the bending characteristics of the prepared oxide solid electrolyte film can be easily controlled, which makes it convenient to adjust the bending characteristics of the oxide solid electrolyte film in different directions according to the application requirements of the oxide solid electrolyte film.

[0051] 3. In the oxide solid electrolyte film prepared in this application, there is a good bonding effect between the solid electrolyte unit and the 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. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of the oxide solid electrolyte film in Example 1.

[0053] Figure 2 This is a schematic diagram of the first multi-line cutting in Example 1.

[0054] Figure 3 This is a schematic diagram of the second multi-wire cutting in Example 1.

[0055] Figure 4 This is a schematic diagram of the structure of the oxide solid electrolyte film in Example 2.

[0056] Figure 5 This is a schematic diagram of the structure of the oxide solid electrolyte film in Example 3.

[0057] In the figure, 1 is a solid electrolyte unit, 2 is a composite solid electrolyte body one, 3 is a composite solid electrolyte body two, and 4 is a disposable fixture. Detailed Implementation

[0058] The present invention will be further described in detail below with reference to the accompanying drawings.

[0059] This application discloses an oxide solid electrolyte thin film, its preparation method, and a solid battery.

[0060] Example 1: Refer to Figure 1-3 A method for preparing an oxide solid electrolyte thin film includes the following steps:

[0061] S1. Rigid solid electrolyte sheets with a certain thickness and length and width dimensions are prepared by ceramic forming and sintering process;

[0062] S2. Stack multiple solid electrolyte sheets in the thickness direction with a certain gap, that is, stack multiple solid electrolyte sheets along the X direction, and set at least one polymer in the gap to prepare composite solid electrolyte body 2.

[0063] S3. Select a thickness stacking surface of the composite solid electrolyte body 2, and perform the first multi-line cut in the direction perpendicular to the stacking of solid electrolyte sheets, that is, perform the first multi-line cut along the Y direction to form multiple solid electrolyte strips on the composite solid electrolyte body 2.

[0064] S4. Clean the composite solid electrolyte body 2 after S3 cutting to remove dirt and waste, and then dry it.

[0065] S5. Place at least one polymer into the slit formed by cutting into S3, and prepare composite solid electrolyte body 23;

[0066] S6. Perform a second multi-line cut on the composite solid electrolyte body 3 in a direction perpendicular to the first multi-line cut, that is, perform a second multi-line cut along the Z direction to obtain an oxide solid electrolyte film.

[0067] S7. Perform surface treatment on the oxide solid electrolyte film obtained in S6.

[0068] The oxide solid electrolyte film prepared by S1-S7 includes multiple solid electrolyte units 1 with rigid structures and at least one polymer with a flexible structure. The polymer has the same thickness as the solid electrolyte unit 1. The polymer is disposed between multiple independent solid electrolyte units 1 and connects multiple solid electrolyte units 1 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 between 0.01 and 100 square millimeters, and the thickness of the oxide solid electrolyte film is between 10 and 100 μm. This gives the oxide solid electrolyte film advantages such as high solid electrolyte density, good bending characteristics, and high ionic conductivity.

[0069] When this oxide solid electrolyte film is applied to a solid-state battery, it is placed between the positive and negative electrodes of the battery, and the two sides of the oxide solid electrolyte film are in surface contact with the positive and negative electrodes, respectively, to serve as a channel for lithium-ion transfer.

[0070] The electrolyte material of solid electrolyte unit 1 includes one or more of the following: garnet type, perovskite type, LISICON type (lithium superion conductor or lithium ion conductor framework structure), NASICON type (sodium superion conductor or sodium ion conductor framework structure), apatite type, spinel type, and amorphous oxide. In specific implementation, lithium zirconium silicon phosphate with LISICON type is selected as solid electrolyte, polyvinyl butyral is selected as binder, dibutyl phthalate is selected as plasticizer, modified fish oil is selected as dispersant, and a mixture of ethanol and butanone is selected as solvent to prepare electrolyte slurry. The preparation process has the advantages of low production cost and high environmental stability. It does not require strict inert atmosphere protection, which reduces the difficulty and cost of production process. Moreover, the prepared solid electrolyte sheet has the advantages of high ionic conductivity, excellent mechanical strength, and strong compatibility.

[0071] The polymers include one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin and rubber. In specific applications, modified polyimide is selected. By introducing ether bonds and sulfone groups into the molecular structure of modified polyimide, the flexibility and polarity of the polymer are enhanced, thereby enhancing the bending characteristics of the oxide solid electrolyte film.

[0072] In the specific implementation of S1, firstly, the electrolyte slurry is cast into a film with a thickness of 0.1-1.5 mm by casting process. Then, the cast film is punched to obtain square films of uniform size. After low temperature debinding and high temperature firing, the square films are used to obtain rigid solid electrolyte sheets with uniform thickness.

[0073] 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.

[0074] In another embodiment, during the preparation of rigid solid electrolyte sheets, a rolling process can be used to replace the casting process to prepare a green ceramic film with a thickness of 0.2-5 mm. Then, the rigid solid electrolyte sheet is obtained by punching, low-temperature debinding, and high-temperature firing of the green ceramic film. At the same time, the rolling process can be used in conjunction with the casting process, such as casting and coating the electrolyte slurry first, and then rolling and compacting to improve the strength of the square film during the punching process.

[0075] In the specific implementation of S2, a 20% concentration of modified polyimide solution is first applied to one surface of the solid electrolyte sheet. After drying and removing the solvent, a 2-5 μm thin film is formed on the surface of the solid electrolyte sheet. Then, the solid electrolyte sheet is flipped over and the same treatment is performed on the other surface.

[0076] After surface treatment with a 20% concentration of modified polyimide solution, a 30% concentration of polyimide solution is first applied to one surface of the solid electrolyte sheet. After drying and solvent removal, a 25-30 μm thin film is formed on the surface. The same treatment is then performed on the other surface, so that polymer films are formed on both sides of the solid electrolyte sheet. This improves the high temperature resistance, lithium dendrite resistance, and mechanical strength of the oxide solid electrolyte film. Solid-state lithium batteries using this oxide solid electrolyte film solve core problems such as interface instability, thermal runaway, and lithium dendrite penetration, thereby improving the energy density, safety, and cycle life of solid-state lithium batteries.

[0077] Multiple solid electrolyte sheets are laid flat or stacked vertically, and then placed on a curing fixture. In this embodiment, multiple solid electrolyte sheets are stacked vertically along the X direction. To prevent the solid electrolyte sheets from loosening, a clamping force is provided on the curing fixture for fixation. Then, the stacked solid electrolyte sheets are placed in a vacuum device and heated to 250-400°C under vacuum conditions, and held at that temperature for 30 minutes. At this temperature, polyimide still has a high viscosity, which can enhance the bonding effect between the solid electrolyte sheets and polyimide. Then, gas is introduced and the gas pressure is increased to 0.1-2 MPa, and hot pressing is performed to prepare composite solid electrolyte body 2.

[0078] To improve the adhesion between the polymer and the solid electrolyte sheet, the surface of the solid electrolyte sheet can be treated before applying the modified polyimide solution.

[0079] In another embodiment, an inorganic slurry is first coated on the surface of the solid electrolyte sheet, dried, and then sintered to form a micro-nano-scale roughened structure on the surface of the solid electrolyte sheet, thereby enhancing the adhesion to the polymer.

[0080] In another embodiment, the solid electrolyte sheet is immersed in a silane coupling agent solution, and after drying and removing the solvent, active groups are formed on the surface of the solid electrolyte sheet to enhance the adhesion to the polymer.

[0081] When implementing S3, refer to Figure 2 A thickness stacking surface of the composite solid electrolyte body 2 is selected, and a first multi-wire cut is performed along the Y direction. In the specific implementation process, a diamond wire with a diameter of 0.12 mm is used for the first multi-wire cut, and the wire spacing is set to 1 mm. After the first multi-wire cut, multiple gaps with a width of about 0.15 mm will be formed on the composite solid electrolyte body 2. At the same time, the single solid electrolyte sheet is cut into multiple solid electrolyte strips with a cross-section of 0.5*1 mm, and the cross-sectional size is the size of a single solid electrolyte unit 1 in the oxide solid electrolyte film obtained in S6.

[0082] 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 to avoid the composite solid electrolyte body 2 becoming loose and affecting subsequent processing, the composite solid electrolyte body 2 is not completely cut through during the first multi-wire cutting.

[0083] To reduce the complexity of subsequent processes, before the first multi-wire cutting, a thick stacked surface of the composite solid electrolyte body 2 is first bonded and fixed to the disposable fixture 4. Then, the opposite surface of the disposable fixture 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.

[0084] In subsequent processes, the disposable fixture 4 can be removed before performing S6, or during the second multi-wire cutting, to facilitate the preparation of the oxide solid electrolyte film.

[0085] In the specific implementation of S4, ultrasonic cleaning equipment is used to clean the composite solid electrolyte body 2 to remove dirt and debris generated during the first multi-wire cutting process. After that, it is placed in a forced-air drying oven for drying treatment, so as to facilitate the treatment of the cut surface of the composite solid electrolyte body 2.

[0086] In the specific implementation of S5, the cut slit of the composite solid electrolyte body 12 is set upwards. Then, the composite solid electrolyte body 12 is placed in a vacuum filling machine. After evacuation, the solid electrolyte body 12 is heated to 250-380℃. Then, polyimide melt at 270-400℃ is poured onto the upper surface of the solid electrolyte body. Since the cut slit of the composite solid electrolyte body 12 is small, the molten polyimide melt cannot flow naturally into the cut slit. The polyimide melt will gradually accumulate on the upper surface of the solid electrolyte body 12. When the cut slit on the upper surface of the solid electrolyte body 12 is completely covered by the polyimide melt, pressurized gas is introduced into the vacuum filling machine. Under the action of gas pressure, the polyimide melt is gradually pressed into the cut slit of the composite solid electrolyte body 12. After continuing to keep it at a temperature for 0.5-1 hour, it is cooled to room temperature according to the set cooling regime. After the polyimide melt cools down, the composite solid electrolyte body 23 is obtained.

[0087] 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 into the vacuum filling 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, so as to improve the adhesion between the composite solid electrolyte body 2 and the polyimide and avoid the problem of individual solid electrolyte units 1 separating on the oxide solid electrolyte film after molding.

[0088] When implementing S6, refer to Figure 3The composite solid electrolyte body 3 is subjected to a second multi-wire cutting along the Z direction to obtain oxide solid electrolyte films with a thickness of 10-100μm. In the specific implementation process, tungsten diamond wire with a diameter of 28μm is selected for the second multi-wire cutting, and the wire spacing is set to 30μm. After cutting, multiple oxide solid electrolyte films with a thickness of 30μm are obtained.

[0089] In the specific implementation of S7, the cut oxide solid electrolyte film is cleaned and dried to obtain the finished oxide solid electrolyte film.

[0090] In the specific implementation process, grinding or polishing is used to further eliminate multi-line cutting marks and improve the surface roughness of oxide solid electrolyte films.

[0091] In one embodiment, the thickness of the oxide solid electrolyte film is further reduced by grinding or polishing.

[0092] Reference Figure 1 In this embodiment, multiple oxide solid electrolyte films with a thickness of 30 μm can be obtained. 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 characteristics, and high ionic conductivity.

[0093] Example 2: A method for preparing an oxide solid electrolyte thin film. The difference between this example and Example 1 is as follows:

[0094] In the specific implementation of S1, a solid electrolyte sheet with a thickness of 0.3 mm and a length and width of 120 mm is prepared by a casting process.

[0095] In the specific implementation of S2, an isolation layer is locally set on the solid electrolyte sheet. Multiple solid electrolyte sheets are stacked along the X direction to form gaps. A polymer is placed in the gaps using a vacuum encapsulation process to prepare the composite solid electrolyte body 2. 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 of the solid electrolyte unit 1 in the prepared oxide solid electrolyte film.

[0096] In the specific implementation process, on one side of the solid electrolyte sheet, two opposite edges are selected, and a 0.1mm thick separator film is locally pasted along the edge of the solid electrolyte sheet. Then, multiple solid electrolyte sheets are stacked to form a uniform gap.

[0097] In the further implementation process, multiple stacked solid electrolyte sheets are clamped and fixed using a fixture to form a solid electrolyte stack. The solid electrolyte stack is then placed into a potting fixture with the gaps between the solid electrolyte sheets facing upwards. After that, the solid electrolyte stack is placed into a vacuum potting machine through the potting fixture. After evacuation, the solid electrolyte stack is heated to 250-380℃. Then, polyimide melt at 270-400℃ is potted on the upper surface of the solid electrolyte stack. Next, pressurized gas is introduced, and under the action of gas pressure, the polyimide melt is pressed into the gaps between the solid electrolyte sheets. After that, the temperature is maintained between 250-380℃ for 0.5-1 hour. After cooling to room temperature according to the set cooling regime, composite solid electrolyte body 2 is formed.

[0098] In another embodiment, in order to improve the bonding effect between polyimide and solid electrolyte sheet, before the solid electrolyte stack is placed into 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, thereby strengthening the bonding force between the solid electrolyte sheet and polyimide.

[0099] In the specific implementation of S3, firstly, one thickness stacked surface of the composite solid electrolyte body 2 is bonded and fixed to the disposable fixture 4. Then, the opposite surface of the disposable fixture 4 is selected for the first multi-wire cutting along the Y direction. In the specific implementation process, the first multi-wire cutting uses diamond wire with a diameter of 0.12mm and the wire spacing is set to 2mm. 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, the single solid electrolyte sheet is cut into multiple solid electrolyte strips with a cross-section of 0.3*2mm and a length of 120mm.

[0100] In a further implementation process, the cut composite solid electrolyte body 2 is processed according to S4 of Example 1.

[0101] In the specific implementation of S5, before the composite solid electrolyte body 2 is placed into the vacuum potting machine, the solid electrolyte body 2 is first immersed in the modified PI solution. After drying and removing the solvent, a modified polyimide film of 2-5μm 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 characteristics of the oxide solid electrolyte film can be further improved.

[0102] In a further implementation, oxide solid electrolyte films were prepared by performing steps S6 and S7 according to Example 1.

[0103] Reference Figure 2In this embodiment, multiple oxide solid electrolyte films with a thickness of 30 μm can be obtained. The size of a single solid electrolyte unit 1 is 0.3*2 mm. The independent solid electrolyte unit 1 has high flexibility in the direction set with a width of 0.3 mm, and can be rolled into a column shape along the width direction of the solid electrolyte unit 1, which can be used for solid batteries with a roll-up design.

[0104] Example 3: A method for preparing an oxide solid electrolyte thin film. The difference between this example and Example 2 is as follows:

[0105] In the specific implementation of S1, a solid electrolyte sheet with a thickness of 1 mm and a length and width of 120 mm is prepared by a casting process.

[0106] In the specific implementation of S2, on one side of the solid electrolyte sheet, two opposite edges are selected, and a separator with a thickness of 0.15mm 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.

[0107] In this embodiment, a clamp is used to clamp and fix multiple stacked solid electrolyte sheets to form a solid electrolyte stack. 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 sheets to improve the bending characteristics of the oxide solid electrolyte film after molding, as well as the bonding effect between the solid electrolyte sheets and the polyimide melt.

[0108] In the further implementation process, the solid electrolyte stack is placed in a potting fixture with the gaps between the solid electrolyte stacks facing upwards. Then, the solid electrolyte stack is placed into a vacuum potting machine through the potting fixture. After evacuation, the solid electrolyte stack is heated to 250-380℃. Then, polyimide melt at 270-400℃ is potted on the upper surface of the solid electrolyte stack. Next, pressurized gas is introduced, and under the action of gas pressure, the polyimide melt is pressed into the gaps between the solid electrolyte sheets. Afterwards, it is kept at 250-380℃ for 0.5-1h. After cooling to room temperature according to the set cooling regime, composite solid electrolyte body 2 is formed.

[0109] In the specific implementation of S3, the first multi-wire cutting uses 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, the single solid electrolyte sheet is cut into multiple solid electrolyte strips with a cross section of 1*1mm and a length of 120mm.

[0110] In a further implementation process, oxide solid electrolyte films were prepared by performing steps S4-S7 according to Example 2.

[0111] Reference Figure 3 In this embodiment, multiple oxide solid electrolyte films with a thickness of 30 μm can be obtained. The size of a single solid electrolyte unit 1 is 1*1 mm. The independent solid electrolyte units 1 are uniformly 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. They exhibit the same bending characteristics in two mutually perpendicular directions. Compared with embodiment 2, this setting can further reduce the area ratio of polymer in the oxide solid electrolyte film and improve the ionic conductivity of the film.

[0112] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An oxide solid state electrolyte thin film, characterized by: It includes multiple solid electrolyte units (1) with rigid structures and at least one polymer with flexible structures. The polymer is disposed between multiple independent solid electrolyte units (1) and the multiple solid electrolyte units (1) are connected to form a large-area oxide solid electrolyte film. The oxide solid electrolyte film is prepared through steps S1-S7 to control the aspect ratio of the solid electrolyte unit (1) and / or the thickness of the oxide solid electrolyte film, specifically including the following steps: S1. Rigid solid electrolyte sheets with a certain thickness and length and width dimensions are prepared by ceramic forming and sintering process; S2. Stack multiple solid electrolyte sheets in the thickness direction with a certain gap, and set at least one polymer in the gap to prepare a composite solid electrolyte body (2). S3. Select a thickness stacking surface of the composite solid electrolyte body one (2), and perform a first multi-line cut in the direction perpendicular to the stacking of solid electrolyte sheets to form multiple solid electrolyte strips on the composite solid electrolyte body one (2). S4. Clean the composite solid electrolyte body (2) after S3 cutting to remove dirt and waste, and dry it. S5. Place at least one polymer into the gap formed by cutting into S3, and prepare composite solid electrolyte body II (3). S6. Perform a second multi-line cut on the composite solid electrolyte body (3) in a direction perpendicular to the first multi-line cut to obtain an oxide solid electrolyte film. S7. Perform surface treatment on the oxide solid electrolyte film obtained in S6.

2. The oxide solid state electrolyte film of claim 1, wherein: 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 state electrolyte thin film of claim 1, wherein: The electrolyte material of the solid electrolyte unit (1) includes one or more of the following: garnet type, perovskite type, LISICON type, NASICON type, apatite type and spinel type. The polymer includes one or more of polyethylene oxide, polyacrylonitrile, polyimide, polyvinylidene fluoride, epoxy resin, and rubber.

4. The oxide solid electrolyte thin film according to claim 1, characterized in that: In S2, the preparation process of the composite solid electrolyte body one (2) is as follows: a polymer solution is coated on the surface of the solid electrolyte sheet, and after drying and removing the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. After stacking multiple solid electrolyte sheets, the composite solid electrolyte body one (2) is prepared by hot pressing under vacuum conditions.

5. The oxide solid electrolyte thin film according to claim 1, characterized in that: In S2, the preparation process of the composite solid electrolyte body one (2) is as follows: a separation layer is locally set on the solid electrolyte sheet, the multiple solid electrolyte sheets are stacked in the thickness direction to form a gap, a polymer is set in the gap by vacuum potting process, and the composite solid electrolyte body one (2) is prepared.

6. The oxide solid electrolyte thin film according to claim 1, characterized in that: In S2, the preparation process of the composite solid electrolyte body one (2) is as follows: a local isolation layer is set on the solid electrolyte sheet, the multiple solid electrolyte sheets are stacked in the thickness direction to form gaps, the stacked solid electrolyte sheets are immersed in a polymer solution, and after drying and removing the solvent, a polymer film is formed on the surface of the solid electrolyte sheet. The polymer is set in the gaps by a vacuum potting process, and the composite solid electrolyte body one (2) is prepared.

7. The oxide solid electrolyte thin film according to claim 1, characterized in that: In S3, a thickness stacking surface of the composite solid electrolyte body (2) is selected and fixed on a disposable fixture (4). Then, the opposite surface of the disposable fixture (4) is selected to perform the first multi-line cutting in the direction perpendicular to the stacking of the solid electrolyte sheets.

8. The oxide solid state electrolyte thin film of claim 1, wherein: In S5, the preparation process of the composite solid electrolyte body II (3) includes: placing a polymer into the gap formed by the first multi-line cutting through a vacuum potting process, and preparing the composite solid electrolyte body II (3).

9. The oxide solid state electrolyte thin film of claim 1, wherein: In S5, the preparation process of the composite solid electrolyte body II (3) is as follows: the composite solid electrolyte body I (2) after cleaning in S4 is immersed in a polymer solution, and after drying and removing the solvent, a polymer film is formed on the surface of the cut gap of the composite solid electrolyte body I (2). The polymer is then placed into the gap through a vacuum potting process, and the composite solid electrolyte body II (3) is prepared.

10. The oxide solid state electrolyte thin film according to claim 4 or 6 or 9, characterized in that: The polymer solution includes one or more of the following: polyimide solution, polyvinylidene fluoride solution, epoxy solution, acrylic solution, silane coupling agent, and modified solution thereof.

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

12. A solid state battery, characterized by: It includes a positive electrode, a negative electrode, and an oxide solid electrolyte film as described in any one of claims 1 to 11, wherein the oxide solid electrolyte film is disposed between the positive electrode and the negative electrode as a channel for lithium-ion transfer.

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