Bottom-coated foil and preparation method, preparation equipment, positive electrode sheet, battery and vehicle

Abstract

This application discloses a base-coated foil, its preparation method, preparation equipment, positive electrode sheet, battery, and vehicle. The base-coated foil includes a conductive substrate and a coating. The coating is disposed on at least one surface of the conductive substrate in a discontinuous distribution. The coating material includes an oxide solid electrolyte, a conductive agent, and a binder. The base-coated foil of this application, by discontinuously distributing a coating containing an oxide solid electrolyte, a conductive agent, and a binder on at least one surface of the conductive substrate, allows it to possess excellent safety performance and conductivity when used as a positive electrode sheet, while also saving costs.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a base-coated foil and its preparation method, preparation equipment, positive electrode sheet, battery, and vehicle. Background Technology

[0002] Currently, the main materials for positive electrode safety undercoatings are lithium iron phosphate and solid electrolytes. Compared to lithium iron phosphate, solid electrolytes have greater potential in terms of safety performance. Solid electrolyte undercoatings help improve the safety performance of battery cells, mainly due to their solid, inorganic ceramic nature. However, although solid electrolytes are lithium-ion conductors, they do not possess electronic conductivity.

[0003] To address this, one related technology discloses a flexible solid electrolyte slurry, comprising a solid electrolyte, cellulose, graphene, and a binder. This slurry is coated onto a positive current collector, and then covered with a positive electrode layer to form a positive electrode sheet. This significantly improves the low-temperature discharge performance and cycle performance of the battery, while also maintaining good mechanical strength and bending flexibility, making it highly valuable for applications. Another related technology discloses a primer slurry and its preparation method. The primer slurry comprises a conductive agent, a binder, and a solid electrolyte. This primer design improves the adhesion between the positive electrode active material and the current collector, while simultaneously increasing the ionic and electronic conductivity of the positive electrode, thereby improving the battery's rate capability and cycle performance. The bottom coating design disclosed in the third related technology includes a second positive electrode layer comprising a positive electrode active material and a lithium-conducting polymer existing in a continuous phase; the positive electrode active material in the first positive electrode layer is selected from lithium iron phosphate; the positive electrode active material in the second positive electrode layer is selected from other active materials besides lithium iron phosphate; this design can effectively improve the transport efficiency of lithium ions and electrons, thereby significantly reducing the resistance of the interface between the positive electrode and the solid electrolyte, and thus improving the lithium conduction capability of the positive electrode. The LFP solid composite positive electrode bottom coating can further improve the safety performance of the battery, and will not cause fire or explosion even during deep charge and discharge.

[0004] The above-mentioned technology adds a lot of conductive agents to the formula during the application of the base coating. Although it improves the battery performance to a certain extent, it also completely covers the positive electrode current collector with materials containing conductive agents and solid electrolytes. On the one hand, it will sacrifice the conductivity of the positive electrode, causing the electrode resistance to increase and thus affecting the internal resistance of the cell. On the other hand, since the solid electrolyte uses more "precious metal ions", it will lead to a higher cost increase.

[0005] Therefore, how to improve the conductivity of the primer design and reduce costs while ensuring safety performance is an urgent technical problem to be solved. Summary of the Invention

[0006] In view of this, one object of this application is to provide a base coating foil with a design that does not fully cover the conductive substrate of the coating containing oxide solid electrolyte, conductive agent and binder, which can balance the effects of increased cost, increased internal resistance and improved safety brought about by the application of solid electrolyte.

[0007] Another objective of this application is to provide a method for preparing a base-coated foil.

[0008] Another object of this application is to provide an apparatus for preparing a base-coated foil.

[0009] Another objective of this application is to provide a positive electrode.

[0010] Another object of this application is to provide a battery.

[0011] Another object of this application is to provide a vehicle.

[0012] To achieve the above objectives, the first aspect of this application provides a base-coated foil material, comprising: Conductive substrate; A coating is provided on at least one surface of the conductive substrate in a discontinuously distributed manner, and the material of the coating includes an oxide solid electrolyte, a conductive agent, and a binder.

[0013] The primer-coated foil material described in this application can bring at least the following beneficial effects: By discontinuously distributing a coating containing an oxide solid electrolyte, a conductive agent, and a binder onto at least one surface of a conductive substrate, it can be used as a positive electrode to achieve both excellent safety performance and conductivity, while also saving costs.

[0014] In some embodiments, the conductive substrate has a surface on which the coating is applied, and the coating coverage is greater than 60% and less than 100%.

[0015] In some embodiments, the coating has a network structure.

[0016] In other embodiments, the coating comprises a plurality of sub-coatings, and the plurality of sub-coatings have at least one of the following characteristics: (1) All of the multiple sub-coatings are strip-shaped; (2) The multiple sub-coatings are arranged at equal intervals; (3) The multiple sub-coatings are arranged in parallel to each other. (4) The plurality of sub-coatings are spaced apart along the first direction of the conductive substrate, and the angle between the first direction and the MD direction is 0-180°.

[0017] In some embodiments, the oxide solid electrolyte includes (LLZO) (LATP) (LAGP) At least one of (LLTO).

[0018] In some embodiments, the mass ratio of the oxide solid electrolyte, the conductive agent, and the binder is (85-95):(0.5-3):(3-8).

[0019] In some embodiments, the material of the coating also includes a dispersant.

[0020] In some embodiments, the coating thickness on one side of the conductive substrate is less than 3 µm.

[0021] The second invention of this application proposes a method for preparing a base-coated foil, comprising: Prepare a target slurry, the target slurry containing the material of the coating; The target slurry is formed on at least one surface of the conductive substrate, and the coating is obtained after curing.

[0022] In some embodiments, forming the target slurry on at least one surface of the conductive substrate includes: forming the target slurry on at least one surface of the conductive substrate using a roller transfer coating method; wherein the roller surface of the transfer roller used in the roller transfer coating has the discontinuously distributed grooves for accommodating the target slurry.

[0023] In some embodiments, the area of ​​the roller surface where the groove is not provided is a smooth area.

[0024] In some embodiments, the total area of ​​the grooves accounts for more than 60% and less than 100% of the total area of ​​the roller surface; In some embodiments, the shape of the groove corresponds to the shape of the coating.

[0025] In some embodiments, the groove has one of the following structures: 1) It has a network structure; 2) Strip structures spaced circumferentially along the transfer roller, wherein the angle between the strip structures and the axis of the transfer roller is 0-180°.

[0026] In some embodiments, the preparation of the target slurry includes: The oxide solid electrolyte, the conductive agent, and the binder are dried to obtain dried oxide solid electrolyte, dried conductive agent, and dried binder; The dried adhesive is dissolved in a portion of a solvent to obtain a glue solution; The dried conductive agent and the dried oxide solid electrolyte are sequentially dispersed in the adhesive solution to obtain a slurry; The viscosity of the slurry is adjusted to the target viscosity using the remaining solvent to obtain the target slurry.

[0027] In some embodiments, the preparation of the target slurry further includes: Before the dried conductive agent and the dried oxide solid electrolyte are sequentially dispersed in the adhesive solution, the dispersant is dispersed in the adhesive solution.

[0028] A third aspect of this application discloses an apparatus for preparing a base-coated foil, comprising: A back roller is used to drive the conductive substrate to move. A transfer roller, disposed on one side of the back roller, is used to coat a target slurry onto at least one surface of the conductive substrate, the target slurry comprising the material of the coating; the roller surface of the transfer roller has the discontinuously distributed grooves for accommodating the target slurry.

[0029] In some embodiments, the area of ​​the roller surface where the groove is not provided is a smooth area.

[0030] In some embodiments, the total area of ​​the grooves accounts for more than 60% and less than 100% of the total area of ​​the roller surface.

[0031] In some embodiments, the shape of the groove corresponds to the shape of the coating.

[0032] In some embodiments, the groove has one of the following structures: 1) It has a network structure; 2) Strip structures spaced circumferentially along the transfer roller, wherein the angle between the strip structures and the axis of the transfer roller is 0-180°.

[0033] A fourth aspect of this application provides a positive electrode sheet, comprising a positive electrode material layer and a base coating foil as described in this application; the positive electrode material layer covers the surface of the base coating foil on which the coating is provided.

[0034] The fifth aspect of this application discloses a battery comprising a positive electrode, a separator, and a negative electrode, characterized in that the positive electrode is the positive electrode described in this application.

[0035] A sixth aspect of this application discloses a vehicle including the battery described in this application.

[0036] The preparation method of the base coating foil, the preparation setup of the base coating foil, the positive electrode sheet, the battery, and the vehicle described in this application all have at least the beneficial effects of the base coating foil described in this application.

[0037] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0038] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings. in: Figure 1 This is a top view of the structure of a base-coated foil, illustrating an exemplary embodiment of this application.

[0039] Figure 2 for Figure 1 Cross-sectional view of surface AA.

[0040] Figure 3 This is a top view of a base-coated foil structure, illustrating another exemplary embodiment of this application.

[0041] Figure 4 This is a top view of the structure of a base-coated foil, which is another exemplary embodiment of this application.

[0042] Figure 5 This is a schematic cross-sectional view of the positive electrode structure shown in an exemplary embodiment of this application.

[0043] Figure 6 This is a perspective view of a transfer roller in a bottom foil preparation apparatus, illustrating an exemplary embodiment of this application.

[0044] Figure 7 This is a schematic diagram of the transfer roller surface structure in a bottom foil preparation apparatus, as shown in an exemplary embodiment of this application.

[0045] Figure 8 A perspective view of a transfer roller in a bottom foil preparation apparatus, illustrating another exemplary embodiment of this application.

[0046] Figure 9 This is a schematic diagram of the transfer roller surface structure in a bottom foil preparation apparatus, as shown in another exemplary embodiment of this application.

[0047] Figure 10 This is a perspective view of a transfer roller in a bottom foil preparation apparatus, as shown in yet another exemplary embodiment of this application.

[0048] Figure 11 This is a schematic diagram of the transfer roller surface structure in a bottom foil preparation apparatus, which is another exemplary embodiment of this application.

[0049] Figure label: 1-Conductive substrate; 2-Coating; 201-Sub-coating; 3-Positive electrode material layer; 4-Smooth surface area; 5-Groove; 6-Target slurry. Detailed Implementation

[0050] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0051] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0052] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0053] When the term “and / or” is used in a list containing two or more items, it means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression “A and / or B” is intended to mean A or B or A and B, that is, A only, B only, or a combination of A and B.

[0054] The term "MD direction" refers to Machine Direction, which is the longitudinal or length direction (sometimes also called the machine conveyor direction).

[0055] The inventors discovered that although the solid electrolyte undercoating technology can improve the lithium-ion conduction capability at the bottom of the positive electrode while enhancing the safety performance of the battery cell, the solid electrolyte material itself does not have the ability to conduct electricity. Covering the bottom of the positive electrode with solid electrolyte will sacrifice the conductivity of the positive electrode and increase the cost.

[0056] Based on the above findings, the inventors accidentally discovered that the oxide solid electrolyte undercoat design with non-full foil coverage can balance the various impacts of increased cost, increased internal resistance, and improved safety brought about by the application of oxide solid electrolytes such as lithium aluminum titanium phosphate (LATP).

[0057] The following description, with reference to the accompanying drawings, describes an embodiment of this application including a base-coated foil, a method for preparing the base-coated foil, equipment for preparing the base-coated foil, and a positive electrode sheet.

[0058] <Base Coated Foil> Figure 1 This is a top view of the structure of a base-coated foil, illustrating an exemplary embodiment of this application. Figure 2This is a side view of the structure of a base-coated foil, illustrating an exemplary embodiment of this application.

[0059] like Figure 1 and Figure 2 As shown, the base coating foil of this application embodiment includes a conductive substrate 1 and a coating 2. The coating 2 is disposed on at least one surface of the conductive substrate 1 in a discontinuous distribution form. The material of the coating 2 includes an oxide solid electrolyte, a conductive agent, and a binder.

[0060] The base-coated foil described in this application has a coating containing an oxide solid electrolyte, a conductive agent, and a binder in a discontinuous distribution on at least one surface of a conductive substrate. This allows it to have excellent safety performance and conductivity when used as a positive electrode, while also saving costs.

[0061] In some embodiments, the conductive substrate 1 has the coating 2 on its surface, and the coating 2 has a coverage of 60% or more but less than 100%. Controlling the coating coverage within this range can balance the needs of safety, improved conductivity, and reduced costs. If the coating coverage is too low, for example, below 60%, the improvement in cell safety may not be significant. If the coating coverage is too high, for example, reaching 100%, the amount of oxide solid electrolyte is too large, resulting in poor conductivity and a significant increase in cost.

[0062] For example, on the surface of the conductive substrate 1 where the coating 2 is provided, the coverage of the coating 2 includes, but is not limited to, 60% or more and less than 100%, 65% or more and less than 100%, 70% or more and less than 100%, 75% or more and less than 100%, 80% or more and less than 100%, 85% or more and less than 100%, 90% or more and less than 100%, 60% or more and less than 90%, 65% or more and less than 90%, and 70% or more. The following are acceptable percentages: above and less than 90%, above 75% and less than 90%, above 80% and less than 90%, above 85% and less than 95%, above 60% and less than 85%, above 65% and less than 85%, above 70% and less than 85%, above 60% and less than 80%, above 65% and less than 80%, above 60% and less than 75%, above 60% and less than 70%, or above 60% and less than 65%, etc. The option "above 60% and below 80%" can also be selected.

[0063] It should be noted that, in the embodiments of this application, there is no limitation on the form in which the coating is discontinuously distributed on the surface of the conductive substrate; it can be any form in which the coating does not completely cover the surface of the conductive substrate.

[0064] As an optional example, such as Figure 1-3As shown, the coating 2 includes multiple sub-coatings 201, and the multiple sub-coatings 201 are spaced apart. There are no restrictions on the method of spacing, the spacing between the spacings, or the shape of the sub-coatings.

[0065] Optionally, the plurality of sub-coatings 201 are spaced apart along a first direction of the conductive substrate 1, wherein the first direction forms an angle of 0-180° with the MD direction.

[0066] Multiple sub-coatings are spaced apart along a first direction of the conductive substrate, which can ensure safety while improving conductivity and reducing costs. In particular, when the angle between the first direction and the MD direction is 0° or 180°, it is easier to process compared to other angles. For example, the angle between the first direction and the MD direction includes, but is not limited to, 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170° or 180°.

[0067] For example, the sub-coating 201 is strip-shaped. In the embodiments of this application, strip-shaped refers to a slender straight line or near-straight line shape with a length much greater than its width, such as a cuboid with a length much greater than its width and a length much greater than its height.

[0068] For example, the plurality of sub-coatings 201 are arranged at equal intervals.

[0069] For example, the plurality of sub-coatings 201 are arranged in parallel to each other.

[0070] In this embodiment, multiple sub-coatings are arranged at equal intervals or / and parallel to each other, which facilitates processing.

[0071] It should be noted that when the plurality of sub-coatings 201 are spaced apart along the first direction of the conductive substrate 1, and the angle between the first direction and the MD direction is 0° or 180°, the plurality of sub-coatings 201 are arranged parallel to the MD direction. In this case, the plurality of sub-coatings can be regarded as a plurality of horizontal sub-coatings disposed on the surface of the conductive substrate. When the plurality of sub-coatings 201 are spaced apart along the first direction of the conductive substrate 1, and the angle between the first direction and the MD direction is greater than 0° and less than 180°, the plurality of sub-coatings are arranged obliquely on the surface of the conductive substrate. If the plurality of sub-coatings 201 are arranged parallel to each other at the same time, the plurality of sub-coatings can be regarded as a plurality of oblique sub-coatings disposed on the surface of the conductive substrate.

[0072] As another alternative example, such as Figure 4As shown, the coating 2 has a mesh structure. The embodiments of this application do not limit the specific form of the mesh structure. Exemplarily, the mesh shape of the mesh structure includes, but is not limited to, at least one of polygons (e.g., rectangles, squares, or triangles), circles, and ellipses. The mesh structure of the coating is a derivative structure of the striped structure. Compared to the striped structure, the mesh structure provides a more uniform coating distribution and superior electrical properties, but it is more difficult to process.

[0073] It should be noted that when the coating 2 has a mesh structure, it can also be regarded as the following situation: multiple sub-coatings 201 are divided into two groups, and multiple sub-coatings 201 in each group are spaced apart and parallel to each other, and the two groups are arranged crosswise.

[0074] In some embodiments, the oxide solid electrolyte includes (LLZO) (LATP) (LAGP) At least one of (LLTO) and others.

[0075] It should be noted that, (LATP) is also known as lithium titanium aluminum phosphate. In the embodiments of this application, the order of preference for LLZO, LATP, LAGP, and LLTO differs depending on whether cost is considered. Specifically: When cost is not a concern, LAGP is the preferred choice, followed by LATP, then LLZO, and finally LLTO. LAGP is favorable for film formation and ion conduction with fewer concerns about Ti valence state; LLZO is chemically stable but has a more demanding process / co-firing window, and is prone to high impedance due to processing; LLTO has greater uncertainty at grain boundaries / interfaces, making it relatively difficult to engineer.

[0076] When considering cost and industrial scale, LATP is the preferred choice, followed by LLZO, then LAGP, and finally LLTO. The reasons are as follows: LATP is often the most practical; LLZO is common in certain pathways (such as the cathode interface layer matched with the LLZO main electrolyte); LAGP is costly; and LLTO has low feasibility.

[0077] As an optional example, the oxide solid electrolyte is lithium titanium aluminum phosphate (LiTiAPO4). The LATP base coating can be further selected as lithium titanium aluminum phosphate with a median particle size (D50) of 0.35-0.65 μm. The LATP base coating helps to improve the safety performance of the battery cell.

[0078] For example, the median particle size (D50) of lithium titanium aluminum phosphate includes, but is not limited to, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm or 0.65 μm, and may be 0.5 μm.

[0079] In some embodiments, the mass ratio of the oxide solid electrolyte, the conductive agent, and the binder is (85-95):(0.5-3):(3-8). It can be understood that the mass ratio of the oxide solid electrolyte, the conductive agent, and the binder can also be interpreted as the coating material containing 85-95 parts by mass of the oxide solid electrolyte, 0.5-3 parts by mass of the conductive agent, and 3-8 parts by mass of the binder. In this case, the mass parts of the oxide solid electrolyte include, but are not limited to, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95 parts, the mass parts of the conductive agent include, but are not limited to, 0.5, 1, 1.5, 2, 2.5, or 3 parts, and the mass parts of the binder include, but are not limited to, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, or 8 parts. The mass fractions of any oxide solid electrolyte, conductive agent, and binder can constitute the above-mentioned mass ratio of oxide solid electrolyte, conductive agent, and binder, and satisfy the mass ratio of oxide solid electrolyte, conductive agent, and binder as (85-95):(0.5-3):(3-8). For example, when the mass fraction of the oxide solid electrolyte is 85 parts, the mass fraction of the conductive agent is 3 parts, and the mass fraction of the binder is 3 parts, then the mass ratio of the oxide solid electrolyte, conductive agent, and binder is 85:3:3. Such mass ratios include, but are not limited to, 90:3:3, 90:0.5:5.5, 90:1.75:3, 90:3:4, 90:3:7, 90:2:5, 90:1:6, 87:3:5, 92:3:3, 92:1.5:4, 87:1:3, 88:1.5:5, 89:2.5:6, or 90:1.5:5, etc., and 92:1.5:4 can be selected.

[0080] In the embodiments of this application, the mass ratio of oxide solid electrolyte, conductive agent and binder is controlled to be (85-95):(0.5-3):(3-8), which can improve safety performance while ensuring conductivity and reducing cost. In addition, it can ensure that the coating and the conductive substrate have a high bonding force.

[0081] It should be noted that, in the embodiments of this application, there are no restrictions on the specific materials selected for the conductive agent and binder. They can be any conductive agent or binder known in the art for use in batteries, especially secondary batteries.

[0082] For example, the conductive agent includes, but is not limited to, at least one of conductive carbon black (e.g., Super P), graphene, carbon fiber, carbon nanotubes, graphite, hard carbon, soft carbon, etc., and may be selected as conductive carbon black.

[0083] For example, the adhesive includes, but is not limited to, polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), and styrene-butadiene rubber (SBR), and may be selected as polyvinylidene fluoride (PVDF).

[0084] In some embodiments, the coating 2 material also includes a dispersant. The dispersant helps improve the processing performance of the base coating foil preparation process, for example, by making the distribution of the raw materials more uniform.

[0085] In some embodiments, the dispersant has a mass content of 1.5-4% in the material of the coating 2, including but not limited to 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or 6.5%, and may be 2.5%.

[0086] As an optional example, when the coating material comprises the oxide solid electrolyte, the conductive agent, the binder, and the dispersant, the mass ratio of the oxide solid electrolyte, the conductive agent, the binder, and the dispersant is (85-95):(0.5-3):(3-8):(1.5-4). Further optionally, when the coating material is composed of the oxide solid electrolyte, the conductive agent, the binder, and the dispersant, the sum of each component is 100%. That is, the coating material consists of the following components in the following mass percentages: 85-95% oxide solid electrolyte, 0.5-3% conductive agent, 3-8% binder, and 1.5-4% dispersant.

[0087] In the embodiments of this application, there is no limitation on the specific substance of the dispersant, which can be any dispersant known in the art for use in batteries, especially secondary batteries.

[0088] For example, the dispersant includes, but is not limited to, at least one of polystyrene, polyanhydride dispersants, polyurethane dispersants, polyacrylic acid dispersants, polyimide dispersants, and inorganic oxide dispersants.

[0089] Among them, polyanhydride dispersants include, but are not limited to, at least one of poly(1,3-phthalic anhydride), poly(maleic anhydride-alt-1-octadecene) / poly(ethylene-alt-maleic anhydride) (PEMA), etc.; polyurethane dispersants include, but are not limited to, at least one of polyether-type aqueous polyurethane dispersions, polycarbonate-type aqueous polyurethane dispersions, BYK-2150 dispersant, etc.; polyacrylic acid dispersants include, but are not limited to, at least one of sodium polyacrylate (PAAS), ammonium polyacrylate (PAA-NH4), DISPERBYK-2010 (modified styrene-maleic anhydride copolymer solution), etc.; and polyimide dispersants include, but are not limited to, polyamide-imide (PAI) and polyetherimide (PEI). At least one of the following, inorganic oxide dispersants include, but are not limited to, at least one of alumina sol, silica sol, etc.

[0090] As an optional example, the dispersant includes at least one of DISPERBYK-2010 (modified styrene-maleic anhydride copolymer solution), BYK-2150 dispersant, etc., with BYK-2150 dispersant being the preferred option.

[0091] In some embodiments, the thickness of the coating 2 on one side of the conductive substrate 1 is less than 3µm, including but not limited to less than 2.8µm, less than 2.6µm, less than 2.4µm, less than 2.2µm, less than 2.0µm, less than 1.8µm, less than 1.6µm, less than 1.4µm, less than 1.2µm, less than 1.0µm, less than 0.8µm, less than 0.6µm, less than 0.4µm, or less than 0.2µm.

[0092] It should be noted that in the embodiments of this application, there is no limitation on the specific selection of the conductive substrate. It can be any positive current collector well known in the art for use in the positive electrode sheet of batteries, especially secondary batteries, such as aluminum foil, carbon-coated aluminum foil, etc.

[0093] <Preparation Method of Base Coated Foil> The method for preparing the base-coated foil in this embodiment can be used to prepare the base-coated foil of this application embodiment. The preparation method includes the following steps: S101. Prepare the target slurry, wherein the target slurry contains the material of the coating; S102. The target slurry is formed on at least one surface of the conductive substrate, and the coating is obtained after curing.

[0094] In some embodiments, step S101, the preparation of the target slurry, includes the following steps: (1) The oxide solid electrolyte, the conductive agent, and the binder are dried to obtain dried oxide solid electrolyte, dried conductive agent, and dried binder; (2) Dissolve the dried adhesive in a portion of the solvent to obtain an adhesive solution; (3) The dried conductive agent and the dried oxide solid electrolyte are sequentially dispersed in the adhesive solution to obtain a slurry; (4) Adjust the viscosity of the slurry to the target viscosity using the remaining solvent to obtain the target slurry.

[0095] In some embodiments, in step S101, at least a portion of the process of preparing the target slurry is carried out under stirring conditions. In the embodiments of this application, the stirring method is not limited and can be any stirring method well known in the art.

[0096] It should be noted that in step S101, the stirring speed during the preparation of the target slurry can remain constant or be adjusted as needed.

[0097] As an optional example, in step S101, the process of preparing the target slurry is carried out in a double planetary tank (a double planetary tank typically refers to the core working vessel (i.e., the tank) used in a double planetary mixer or double planetary agitator; the preparation process may involve low-speed stirring, medium-speed stirring, and high-speed stirring, etc.). However, it should be noted that different specifications of double planetary tanks may have different speed limits for low-speed, medium-speed, and high-speed stirring, but overall, the low-speed stirring speed must be lower than the medium-speed stirring speed, and the medium-speed stirring speed must be lower than the high-speed stirring speed. For example, a 60L double planetary tank is used. The low-speed stirring setting is 12-18 rpm for revolution and 960-1440 rpm for rotation. For example, the revolution speed includes but is not limited to 13 rpm, 15 rpm or 17 rpm, and the rotation speed includes but is not limited to 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm or 1400 rpm. The selectable settings are 15 rpm for revolution and 1200 rpm for rotation.

[0098] The medium-speed mixing setting is a revolution speed of 20-30 rpm and a rotation speed of 1920-2880 rpm. For example, the revolution speed includes but is not limited to 22 rpm, 25 rpm or 27 rpm, and the rotation speed includes but is not limited to 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm or 2800 rpm. The selectable settings are a revolution speed of 25 rpm and a rotation speed of 2400 rpm.

[0099] The high-speed mixing setting is 25-35 rpm for revolution and 2560-3840 rpm for rotation. For example, the revolution speed includes but is not limited to 28 rpm, 30 rpm or 33 rpm, and the rotation speed includes but is not limited to 2600 rpm, 2800 rpm, 3000 rpm, 3200 rpm, 3400 rpm, 3600 rpm or 3800 rpm. The selectable settings are 30 rpm for revolution and 3200 rpm for rotation.

[0100] The aforementioned low-speed, medium-speed, and high-speed stirring, if measured solely by stirring speed, can also be referred to as low-speed stirring, medium-speed stirring, and high-speed stirring. The following discussion of low-speed, medium-speed, and high-speed stirring should at least be based on the speed limits of low-speed, medium-speed, and high-speed stirring in a 60L double planetary tank.

[0101] In the embodiments of this application, drying the oxide solid electrolyte, the conductive agent, and the binder is a pretreatment process to thoroughly remove moisture. The drying method is not limited and can include vacuum oven drying, spray drying, forced-air drying, etc., with vacuum oven drying being a preferred option.

[0102] In some embodiments, the temperature at which the oxide solid electrolyte and the conductive agent are dried in step (1) is 110-130°C, including but not limited to 115°C, 120°C or 125°C, and can be selected as 120°C; the drying time is more than 12 hours, including but not limited to 14 hours, 16 hours, 18 hours or 20 hours, and can be selected as 12-16 hours.

[0103] In some embodiments, the temperature at which the adhesive is dried in step (1) is 70-90°C, including but not limited to 75°C, 80°C or 85°C, and can be selected as 80°C; the drying time is more than 12 hours, including but not limited to 14 hours, 16 hours, 18 hours or 20 hours, and can be selected as 12-16 hours.

[0104] In some embodiments, the solvent in step (2) includes, but is not limited to, at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dichlorotoluene, etc., and may be N-methylpyrrolidone (NMP).

[0105] In some embodiments, step (2) involves dissolving the dried adhesive in a portion of a solvent, including: While stirring at low speed, slowly and in batches add the weighed and dried binder to the solvent; after the addition is complete, increase the stirring speed and continue stirring for 2-4 hours (e.g., 2.5 hours, 3 hours, or 3.5 hours) until the binder is completely dissolved and a homogeneous, transparent, and viscous solution is formed.

[0106] In some embodiments, step (3) involves sequentially dispersing the dried conductive agent and the dried oxide solid electrolyte in the adhesive solution, including: Adjust the stirring speed to a low speed (i.e., low-speed stirring) to prevent dust from flying. Slowly add the weighed, dried conductive agent. After adding all the agent, increase the speed to medium speed (i.e., medium-speed stirring) and continue stirring for 20-40 minutes (e.g., 30 minutes) to ensure the conductive agent is completely coated and dispersed in the liquid phase. Reduce the speed again (i.e., low-speed stirring) and slowly add the dried solid electrolyte in batches. After all the powder has been added, cover the container and gradually increase the speed (e.g., first medium-speed stirring, then high-speed stirring) for high-speed dispersion (i.e., high-speed stirring) for 60-90 minutes (e.g., 70 or 80 minutes). During this period, use a scraper to clean the slurry from the walls and bottom of the container three times to ensure uniform dispersion.

[0107] In some embodiments, the preparation of the target slurry further includes: Before the dried conductive agent and the dried oxide solid electrolyte are sequentially dispersed in the adhesive solution, the dispersant is dispersed in the adhesive solution.

[0108] For example, the dispersant is dispersed in the adhesive solution under stirring conditions, and the stirring speed is medium (i.e., medium-speed stirring).

[0109] In some embodiments, step (4), adjusting the viscosity of the slurry to the target viscosity using the remaining solvent, includes: Stop stirring and check the viscosity and flowability of the slurry. Adjust the slurry using the remaining solvent, adding it gradually and mixing thoroughly until the target viscosity (500-4000 mPas) is reached. After adjustment, switch to planetary mixer rotation. Rotation mode (also known as high-speed dispersion mode or high-speed stirring) for 20-40 minutes (e.g., 30 minutes, etc.) to perform high-shear dispersion, so that the slurry reaches a highly uniform state.

[0110] For example, the target viscosity is 500-4000 mPas, including but not limited to 600 mPas, 700 mPas, 800 mPas, 900 mPas, 1000 mPas, 1100 mPas, 1200 mPas, 1300 mPas, 1400 mPas, 1500 mPas, 1600 mPas, 1700 mPas, 1800 mPas, 1900 mPas, 2000 mPas, 2250 mPas, 2500 mPas, 2750 mPas, 3000 mPas, 3250 mPas, 3500 mPas, or 3750 mPas, etc., and can be selected as 500-2000 mPas.

[0111] It should be noted that in step S102, there is no limitation on the method of forming the target slurry on at least one surface of the conductive substrate. It can be any method known in the art, as long as it can achieve a discontinuous distribution of the coating on at least one surface of the conductive substrate. For example, in some embodiments, the method of forming the target slurry on at least one surface of the conductive substrate can be scraping, spraying, etc.

[0112] In other embodiments, the coverage and morphology of the primer coating are controlled by designing the transfer roller in the roller-type transfer coating process. In embodiments where the primer coating does not fully cover the substrate, a special transfer roller is used, characterized by a concave morphology on its surface. The engraved area of ​​this roller is not continuous but consists of a series of grooves (corresponding to the coating in the primer foil) and smooth areas (corresponding to the areas of the conductive substrate in the primer foil that are not covered by the coating). The coverage of the coating in the primer foil is achieved by designing different ratios between the size of the grooved areas and the smooth areas. Specifically: In step S102, forming the target slurry on at least one surface of the conductive substrate includes: forming the target slurry on at least one surface of the conductive substrate using a roller transfer coating method; the roller surface of the transfer roller used in the roller transfer coating has the discontinuously distributed grooves 5, the grooves 5 being used to accommodate the target slurry.

[0113] For ease of description, in the embodiments of this application, the target slurry is represented by reference numeral 6, such as... Figure 7 , Figure 9 and Figure 11 As shown.

[0114] In some embodiments, the area of ​​the roller surface where the groove 5 is not provided is a smooth area 4.

[0115] In some embodiments, the total area of ​​the grooves 5 accounts for more than 60% and less than 100% of the total area of ​​the roller surface, including but not limited to: more than 60% and less than 100%, more than 65% and less than 100%, more than 70% and less than 100%, more than 75% and less than 100%, more than 80% and less than 100%, more than 85% and less than 100%, more than 90% and less than 100%, more than 60% and less than 90%, more than 65% and less than 90%, and so on. The following percentages can be selected: 70% or more but less than 90%, 75% or more but less than 90%, 80% or more but less than 90%, 85% or more but less than 95%, 60% or more but less than 85%, 65% or more but less than 85%, 70% or more but less than 85%, 60% or more but less than 80%, 65% or more but less than 80%, 60% or more but less than 75%, 60% or more but less than 70%, or 60% or more but less than 65%, etc. The option "60% or more but less than 80%" can also be selected.

[0116] In some embodiments, the shape of the groove 5 is similar to the shape of the coating 2 to facilitate the formation of a coating in the undercoating foil on the conductive substrate.

[0117] In some embodiments, the groove 5 has one of the following structures: 1) It has a network structure (such as...) Figure 9 and Figure 10 (as shown) 2) Strip-shaped structures spaced circumferentially along the transfer roller, wherein the angle between the strip-shaped structures and the axis of the transfer roller is 0-180° (e.g., Figure 6 , Figure 7 , Figure 8 and Figure 9 (As shown), including but not limited to 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°, etc. Where the angle between the strip structure and the axis of the transfer roller is 0° or 180°, such as... Figure 6 and Figure 7 As shown, this can be used to prepare coatings where multiple sub-coatings 201 are arranged parallel to the MD direction (see...). Figure 1 and Figure 2 When the angle between the strip structure and the transfer roller shaft is greater than 0° and less than 180°, such as... Figure 8 and Figure 9 As shown, this can be used to prepare coatings where multiple sub-coatings are tilted on the surface of a conductive substrate (see above). Figure 3 ).

[0118] When the groove 5 has a mesh structure, the mesh structure is intended to form a mesh structure coating in the base coating foil. Therefore, the mesh structures of the two are consistent. The difference is that the mesh structure coating of the base coating foil is provided on at least one surface of the conductive substrate, while the mesh structure of the transfer roller surface refers to the groove having a mesh structure. The groove is opened on the roller surface of the transfer roller and forms a mesh structure on the roller surface.

[0119] When the groove 5 is a strip-shaped structure distributed circumferentially along the transfer roller, it is intended to form a coating with multiple sub-coatings in the base coating foil. Therefore, the structure of the groove is consistent with the structure of a coating with multiple sub-coatings. The difference is that the coating of the base coating foil containing multiple strip-shaped sub-coatings is provided on at least one surface of the conductive substrate, while the strip-shaped structure of the transfer roller surface refers to the groove having a strip-shaped structure, and the groove is opened on the roller surface of the transfer roller.

[0120] It should be noted that roller transfer coating also includes a back roller, which can carry the conductive substrate. In some embodiments, the method of forming the target slurry on at least one surface of the conductive substrate using roller transfer coating includes: The target slurry 6 from the feed trough enters the groove 5 through the feed channel of the transfer roller. When the transfer roller rotates and encounters the back roller carrying the conductive substrate 1, the target slurry 6 in the groove 5 will be coated on the surface of the conductive substrate 1. However, the smooth area without the groove 5 directly contacts the surface of the conductive substrate 1 and will not be coated with the target slurry.

[0121] It should be noted that, in the embodiments of this application, the method of forming the target slurry on at least one surface of the conductive substrate is not limited to the implementation method described in the embodiments of this application. As long as the base coating foil of the embodiments of this application can be prepared, it can be any method known in the art, such as scraping, spraying, etc. However, the working efficiency of scraping, spraying, etc. will be much lower than that of this application, which is not conducive to mass production and industrialization.

[0122] Furthermore, in the embodiments of this application, the curing method is not limited and can be any method well known in the art, such as drying curing, baking curing, etc., with drying curing being an option.

[0123] <Preparation equipment for base-coated foil> The equipment for preparing the base-coated foil in this application is essentially an improvement on existing roller-type transfer coating equipment. The main improvement lies in the discontinuously distributed groove design on the transfer roller surface. This equipment can be used to prepare the base-coated foil and the preparation method of the base-coated foil in this application.

[0124] The apparatus for preparing the base coating foil according to various embodiments of this application includes a back roller and a transfer roller. The back roller is used to move the conductive substrate 1. The transfer roller is disposed on one side of the back roller and is used to coat at least one surface of the conductive substrate 1 with a target slurry. The target slurry includes the material of the coating 2. The roller surface of the transfer roller has discontinuously distributed grooves 5, which are used to accommodate the target slurry 6.

[0125] In some embodiments, the area of ​​the roller surface where the groove 5 is not provided is a smooth area 4.

[0126] In some embodiments, the total area of ​​the grooves 5 accounts for more than 60% and less than 100% of the total area of ​​the roller surface, including but not limited to: more than 60% and less than 100%, more than 65% and less than 100%, more than 70% and less than 100%, more than 75% and less than 100%, more than 80% and less than 100%, more than 85% and less than 100%, more than 90% and less than 100%, more than 60% and less than 90%, and more than 65% and less than 90%. The percentages are: above 70% and below 90%, above 75% and below 90%, above 80% and below 90%, above 85% and below 95%, above 60% and below 85%, above 65% and below 85%, above 70% and below 85%, above 60% and below 80%, above 65% and below 80%, above 60% and below 75%, above 60% and below 70%, or above 60% and below 65%, etc., and can be selected as above 60% and below 80%.

[0127] In some embodiments, the shape of the groove 5 is similar to the shape of the coating 2 to facilitate the formation of a coating in the undercoating foil on the conductive substrate.

[0128] In some embodiments, the groove 5 has one of the following structures: 1) It has a network structure (such as...) Figure 9 and Figure 10 (as shown) 2) Strip-shaped structures spaced circumferentially along the transfer roller, wherein the angle between the strip-shaped structures and the axis of the transfer roller is 0-180° (e.g., Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown), including but not limited to 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, or 170°. Where the angle between the strip structure and the axis of the transfer roller is 0° or 180°, such as... Figure 6 and Figure 7As shown, this can be used to prepare coatings where multiple sub-coatings 201 are arranged parallel to the MD direction (see...). Figure 1 and Figure 2 When the angle between the strip structure and the transfer roller shaft is greater than 0° and less than 180°, such as... Figure 8 and Figure 9 As shown, this can be used to prepare coatings where multiple sub-coatings are tilted on the surface of a conductive substrate (see above). Figure 3 ).

[0129] When the groove 5 has a mesh structure, the mesh structure is intended to form a mesh structure coating in the base coating foil. Therefore, the mesh structures of the two are consistent. The difference is that the mesh structure coating of the base coating foil is provided on at least one surface of the conductive substrate, while the mesh structure of the transfer roller surface refers to the groove having a mesh structure. The groove is opened on the roller surface of the transfer roller and forms a mesh structure on the roller surface.

[0130] When the groove 5 is a strip-shaped structure distributed circumferentially along the transfer roller, it is intended to form a coating with multiple sub-coatings in the base coating foil. Therefore, the structure of the groove is consistent with the structure of a coating with multiple sub-coatings. The difference is that the coating of the base coating foil containing multiple strip-shaped sub-coatings is provided on at least one surface of the conductive substrate, while the strip-shaped structure of the transfer roller surface refers to the groove having a strip-shaped structure, and the groove is opened on the roller surface of the transfer roller.

[0131] The method for preparing the base-coated foil according to the embodiments of this application using the base-coated foil equipment includes: The target slurry 6 from the feed trough enters the groove 5 through the feed channel of the transfer roller. When the transfer roller rotates and encounters the back roller carrying the conductive substrate 1, the target slurry 6 in the groove 5 will be coated on the surface of the conductive substrate 1. However, the smooth area without the groove 5 directly contacts the surface of the conductive substrate 1 and will not be coated with the target slurry.

[0132] <Positive Electrode Tablets> Figure 5 This is a side view of the positive electrode structure shown in an exemplary embodiment of this application.

[0133] like Figure 5 As shown, the positive electrode sheet includes a positive electrode material layer 3 and a base coating foil according to the present application embodiment; the positive electrode material layer 3 covers the surface of the base coating foil on which the coating 2 is provided.

[0134] Understandably, the positive electrode material layer covers not only the surface of the coating layer but also the areas of the conductive substrate in the primer foil that are not covered by the coating layer. The surface of the positive electrode material layer away from the conductive substrate is parallel to the conductive substrate. Figure 5 As shown.

[0135] In some embodiments, the positive electrode material layer includes a positive electrode active material, a positive electrode conductive agent, a positive electrode binder, etc.

[0136] It should be noted that in the embodiments of this application, there are no restrictions on the selection and amount of positive electrode active material, positive electrode conductive agent, positive electrode binder, etc., which can be any battery well known in the art, especially secondary batteries (e.g., lithium-ion batteries).

[0137] <Battery> The battery in this application embodiment includes a positive electrode, a separator, and a negative electrode, wherein the positive electrode is the positive electrode of this application embodiment.

[0138] In some embodiments, the battery is a secondary battery, such as a lithium-ion battery or a sodium-ion battery, and lithium-ion batteries may be selected.

[0139] <Vehicles> The vehicle in this application embodiment includes the battery in this application embodiment.

[0140] In some embodiments, the vehicle includes electric vehicles, electric motorcycles, etc., and may be an electric vehicle.

[0141] The following non-limiting embodiments further illustrate certain features of the present technology.

[0142] I. Examples and Comparative Examples In the following embodiments and comparative examples, unless otherwise specified, equal spacing means that the spacing between two adjacent sub-coatings is equal.

[0143] Example 1 (Base coating foil) like Figure 1 and Figure 2 As shown, the base coating foil of this embodiment includes a conductive substrate 1 and a coating 2 disposed on the upper and lower surfaces of the conductive substrate 1. The conductive substrate 1 is a cuboid aluminum foil with a thickness of 12 μm, and the coating 2 has a coverage of 85% on its surface.

[0144] The material of coating 2 consists of the following components by mass percentage: 92% oxide solid electrolyte, 1.5% conductive agent, 4% binder, and 2.5% dispersant. The oxide solid electrolyte is lithium aluminum titanium phosphate (LATP), the conductive agent is conductive carbon black (Super P), the binder is PVDF, and the dispersant is BYK-2150.

[0145] The coating 2 includes multiple sub-coatings 201, which are parallel to each other and equally spaced (the distance between two adjacent sub-coatings 201 is 1 mm) and distributed along a first direction on the surface of the conductive substrate 1. The first direction makes an angle of 0° with the MD direction. The sub-coatings 201 are strip-shaped (that is, the multiple sub-coatings are equally spaced stripes), specifically, they are cuboids with the same length as the conductive substrate, a width of 6 mm, and a thickness of 2 μm (that is, the thickness of the coating 2 on its surface is 2 μm).

[0146] (Equipment for preparing base-coated foil) like Figure 6 and Figure 7 As shown, the equipment for preparing the base coating foil in this embodiment includes a back roller and a transfer roller. The back roller is used to move the conductive substrate 1. The transfer roller is disposed on one side of the back roller and is used to coat the surface of the conductive substrate 1 with the coating material 2. The roller surface of the transfer roller is provided with a plurality of grooves 5 at equal intervals along the circumference of the transfer roller. The plurality of grooves 5 are all at an angle of 0° with the axis of the transfer roller. The distance between two adjacent grooves 5 is 1 mm. The grooves 5 can be used to accommodate the target slurry 6 of the coating material 2. The grooves 5 are cuboids with a width of 6 mm and a depth of 3 mm. The total area of ​​the plurality of grooves 5 accounts for 85% of the total area of ​​the roller surface of the transfer roller. The area of ​​the roller surface of the transfer roller without grooves 5 is the smooth area 4.

[0147] (Preparation method of base-coated foil) The method for preparing the base-coated foil in this embodiment includes the following steps: (1) Pretreatment Drying raw materials: The oxide solid electrolyte and conductive agent were dried in a vacuum oven at 120°C for 13 hours to obtain the dried oxide solid electrolyte and the dried conductive agent. The binder was dried at 80°C for 3 hours to obtain the dried binder.

[0148] Prepare the solvent: Weigh most of the required N-methylpyrrolidone (NMP) solvent into a slurry tank, which is a 60L double planetary tank.

[0149] (2) Preparation of adhesive solution While stirring at low speed (15 rpm revolution, 1200 rpm rotation), the dry binder is slowly and in batches added to the NMP solvent. After the addition is complete, the stirring speed is increased to medium speed (25 rpm revolution, 2400 rpm rotation) and stirring is continued for 3 hours until completely dissolved, forming a homogeneous, transparent, and viscous solution, which is the adhesive.

[0150] (3) Adding additives Under medium stirring conditions (25 rpm revolution and 2400 rpm rotation), a dispersant was added to the adhesive solution, and stirring was continued for 30 minutes to fully disperse and activate the additives, thus obtaining a mixture.

[0151] (4) Mixing solid powders Adjust the stirring speed to a low setting (15 rpm revolution, 1200 rpm rotation) and slowly add the dried conductive agent to the mixture. After adding the agent, increase the stirring speed to a high setting (30 rpm revolution, 3200 rpm rotation) and continue stirring for 30 minutes to ensure the conductive agent is completely coated and dispersed in the liquid phase. Reduce the stirring speed back to a low setting (15 rpm revolution, 1200 rpm rotation) and slowly add the dried oxide solid electrolyte in batches. After all materials have been added, cover the container and gradually increase the stirring speed (first medium speed stirring (25 rpm revolution, 2400 rpm rotation), then high speed stirring (30 rpm revolution, 3200 rpm rotation)) for high-speed dispersion for 75 minutes. During this period, use a scraper to clean the slurry from the walls and bottom of the container three times to ensure uniform dispersion.

[0152] (5) Adjustment and final dispersion Stop stirring and check the viscosity and flowability of the slurry. Adjust the slurry using the remaining NMP solvent, adding it gradually and mixing thoroughly until the target viscosity of 2000 mPas is reached. After adjustment, switch to planetary mixer rotation. Rotation mode for 30 minutes, high shear dispersion (i.e., high-speed stirring (revolution 30 rpm, rotation 3200 rpm)) is performed to make the slurry reach a highly uniform state, and the target slurry 6 is obtained.

[0153] (6) Coating The coating is performed using the equipment for preparing the base-coated foil according to this embodiment. Specifically, the target slurry 6 from the feed tank enters the groove 5 through the feed channel of the transfer roller. When the transfer roller rotates and encounters the back roller carrying the conductive substrate 1, the target slurry 6 in the groove 5 will be coated onto the surface of the conductive substrate 1. The smooth area without the groove 5 directly contacts the surface of the conductive substrate 1 and will not be coated with the target slurry. Subsequently, it is dried and cured to obtain the base-coated foil of this embodiment.

[0154] Example 2 This embodiment is basically the same as embodiment 1, except that: In the base coating foil, the coverage of coating 2 on its surface is 75%, and the sub-coating 201 is strip-shaped (that is, multiple sub-coatings are equally spaced stripes), specifically a cuboid with the same length as the conductive substrate, a width of 3 mm, and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm); the spacing between two adjacent sub-coatings 201 is 1 mm.

[0155] In the equipment for preparing the base coating foil, the total area of ​​multiple grooves 5 accounts for 75% of the total area of ​​the transfer roller surface, and the width of the grooves 5 is 3mm.

[0156] Example 3 This embodiment is basically the same as embodiment 1, except that: In base-coated foil materials: Coating 2 has a coverage of 75% on the surface it is applied to; such as Figure 3 As shown, multiple sub-coatings 201 are parallel to each other and equally spaced along the first direction on the surface of the conductive substrate 1. The angle between the first direction and the MD direction is 45°. The sub-coatings 201 are strip-shaped (i.e., multiple sub-coatings are equally spaced stripes), with a width of 3 mm and a thickness of 2 μm (i.e., the thickness of coating 2 on its surface is 2 μm). The spacing between two adjacent sub-coatings 201 is 1 mm.

[0157] In the equipment for preparing base-coated foil: The groove 5 is elongated and similar in shape to the sub-coating; the total area of ​​the multiple grooves 5 accounts for 75% of the total area of ​​the transfer roller surface; the width of the groove 5 is 3mm.

[0158] Example 4 This embodiment is basically the same as embodiment 1, except that: In base-coated foil materials: like Figure 4 As shown, the coverage of coating 2 on its surface is 75%; coating 2 has a mesh structure with rectangular mesh openings. The mesh structure is formed by the intersection of multiple rectangular strip-shaped sub-coatings (i.e., stripes) with a width of 2 mm and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm). In two sets of rectangular strip-shaped sub-coatings with different directions of intersection, one set has an angle of 0° with the MD direction and the other set has an angle of 90° with the MD direction. The spacing between two adjacent rectangular strip-shaped sub-coatings in each set of rectangular strip-shaped sub-coatings with the same direction is 2 mm (that is, a mesh stripe is formed).

[0159] In the equipment for preparing base-coated foil: The following is a change from "The transfer roller has multiple grooves 5 evenly spaced along its circumference, each groove 5 has an angle of 0° with the axis of the transfer roller, the distance between two adjacent grooves 5 is 1mm, the grooves 5 can be used to hold the target slurry 6 of the coating material 2; the grooves 5 are cuboids with a width of 6mm and a depth of 3mm; the total area of ​​the multiple grooves 5 accounts for 85% of the total area of ​​the transfer roller surface" to: The transfer roller has grooves 5 on its surface. The grooves 5 have a mesh structure and their shape is similar to that of the coating 2 in this embodiment. The depth of the grooves is 3 mm, and the total area of ​​the grooves 5 accounts for 75% of the total area of ​​the transfer roller surface.

[0160] Example 5 This embodiment is basically the same as embodiment 1, except that: In the base coating foil, the coverage of coating 2 on its surface is 60%, and the sub-coating 201 is strip-shaped (that is, multiple sub-coatings are equally spaced stripes). Specifically, it is a cuboid with the same length as the conductive substrate, a width of 3 mm, and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm). The spacing between two adjacent sub-coatings 201 is 2 mm.

[0161] In the equipment for preparing the base coating foil, the total area of ​​multiple grooves 5 accounts for 60% of the total area of ​​the transfer roller surface, the width of the groove 5 is 3mm, and the distance between two adjacent grooves 5 is 2mm.

[0162] Example 6 This embodiment is basically the same as embodiment 1, except that: In base-coated foil materials: like Figure 4 As shown, the coverage of coating 2 on its surface is 98%; coating 2 has a mesh structure with rectangular mesh openings. The mesh structure is formed by multiple rectangular strip-shaped sub-coatings (i.e., stripes) with a width of 6 mm and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm). In two sets of rectangular strip-shaped sub-coatings with different directions of intersection, one set has an angle of 0° with the MD direction and the other set has an angle of 90° with the MD direction. The spacing between two adjacent rectangular strip-shaped sub-coatings in each set of rectangular strip-shaped sub-coatings with the same direction is 1 mm (that is, a mesh stripe is formed).

[0163] In the equipment for preparing base-coated foil: The following is a change from "The transfer roller has multiple grooves 5 evenly spaced along its circumference, each groove 5 has an angle of 0° with the axis of the transfer roller, the distance between two adjacent grooves 5 is 1mm, the grooves 5 can be used to hold the target slurry 6 of the coating material 2; the grooves 5 are cuboids with a width of 6mm and a depth of 3mm; the total area of ​​the multiple grooves 5 accounts for 85% of the total area of ​​the transfer roller surface" to: The transfer roller has grooves 5 on its surface. The grooves 5 have a mesh structure and their shape is similar to that of the coating 2 in this embodiment. The depth of the grooves is 3 mm, and the total area of ​​the grooves 5 accounts for 98% of the total area of ​​the transfer roller surface.

[0164] Example 7 This embodiment is basically the same as embodiment 2, except that: The material of coating 2 is composed of the following components by mass percentage: 95% oxide solid electrolyte, 0.5% conductive agent, 3% binder, and 1.5% dispersant.

[0165] Example 8 This embodiment is basically the same as embodiment 2, except that: The material of coating 2 is composed of the following components by mass percentage: 85% oxide solid electrolyte, 3% conductive agent, 8% binder, and 4% dispersant.

[0166] Example 9 This embodiment is basically the same as embodiment 2, except that: oxide solid electrolyte is (LLZO).

[0167] Comparative Example 1 This comparative example is the case where the conductive substrate surface in Example 1 is not coated with coating 2, that is, the conductive substrate itself in Example 1.

[0168] Comparative Example 2 This comparative example is basically the same as Example 1, except that: In the base-coated foil, coating 2 is a single unit with a thickness of 2 micrometers and a coverage of 100% on its surface.

[0169] In the base coating foil equipment, the roller surface of the transfer roller is entirely smooth and does not contain grooves.

[0170] In the preparation method of the base-coated foil: In step (5), continue until the target viscosity of 3500 mPas is reached.

[0171] In step (6), the preparation equipment for the base-coated foil of this comparative example is used for coating. Specifically, the target slurry 6 from the trough is transferred to the surface of the conductive substrate by a roller, and then dried and cured to obtain the base-coated foil of this comparative example.

[0172] Comparative Example 3 This comparative example is basically the same as Example 1, except that: In the base coating foil, the coverage of coating 2 on its surface is 45%, and the sub-coating 201 is strip-shaped (that is, multiple sub-coatings are equally spaced stripes). Specifically, it is a cuboid with the same length as the conductive substrate, a width of 3 mm, and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm). The spacing between two adjacent sub-coatings 201 is 3.5 mm.

[0173] In the equipment for preparing the base coating foil, the total area of ​​multiple grooves 5 accounts for 45% of the total area of ​​the transfer roller surface. The width of the groove 5 is 3mm, and the distance between two adjacent grooves 5 is 3.5mm.

[0174] Comparative Example 4 This comparative example is basically the same as Example 1, except that: In the base coating foil, the coverage of coating 2 on its surface is 33%, and the sub-coating 201 is strip-shaped (that is, multiple sub-coatings are equally spaced stripes). Specifically, it is a cuboid with the same length as the conductive substrate, a width of 3 mm, and a thickness of 2 μm (that is, the thickness of coating 2 on its surface is 2 μm). The spacing between two adjacent sub-coatings 201 is 4 mm.

[0175] In the equipment for preparing the base coating foil, the total area of ​​multiple grooves 5 accounts for 33% of the total area of ​​the transfer roller surface, the width of the groove 5 is 3mm, and the distance between two adjacent grooves 5 is 4mm.

[0176] II. Performance Testing The base-coated foils from each embodiment and comparative example were used to prepare positive electrode sheets, which were then used to fabricate lithium-ion batteries. The resistivity of each positive electrode sheet and the safety performance of each lithium-ion battery were tested. Wherein: The preparation method of the positive electrode sheet includes: mixing the positive electrode active material 4.48V lithium cobalt oxide, the positive electrode conductive agent multi-walled carbon nanotubes, the positive electrode conductive agent conductive carbon black (Super P), and the positive electrode binder polyvinylidene fluoride (PVDF) in a mass ratio of 98.2wt%:0.8wt%:0.4wt%:0.6wt%, and then uniformly dispersing them in the solvent N-methylpyrrolidone (NMP) to obtain a positive electrode slurry with a solid content of 76%. The positive electrode slurry is then coated onto the opposite two surfaces of the base coating foil in each embodiment or comparative example (Comparative Example 1 uses the conductive substrate itself). (For the embodiments, the coating is applied to the opposite two surfaces of the base foil where a coating is provided, such as in Example 1, etc.). Figure 5 As shown in the figure, the material was then dried, rolled, and cut to obtain a positive electrode with a positive active material content of 98.2% and an areal density of 15.3 mg / cm³. 2 The positive electrode compaction density is 4.05 g / cm³. 3 The positive electrode plate.

[0177] The lithium-ion battery has a full-cell design capacity of 5200mAh, and its preparation method includes: (1) Preparation of negative electrode sheet: The negative electrode active material Shanshan 5C fast-charging graphite, the negative electrode conductive agent conductive carbon black (SuperP), the negative electrode binder SBR, and the negative electrode thickener CMC were mixed at a mass ratio of 96.8:0.5:1.5:1.2 and uniformly dispersed in deionized water to obtain a negative electrode slurry with a solid content of 50%. The negative electrode slurry was coated on the opposite surfaces of a copper foil with a thickness of 8 μm, and then dried, rolled, and cut to obtain a negative electrode with an active material content of 96.8% and an areal density of 6.2 mg / cm³. 2 The negative electrode compaction density is 1.60 g / cm³. 3 The negative electrode.

[0178] (2) Electrolyte: A standard 5C fast-charging electrolyte is used. Specifically: 1M The solvent is a mixed solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), propyl propionate (PP), and methyl propionate (EP) in a volume percentage of EC:EMC:PP:EP = 20%:40%:15%:25%. The additives consist of vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium difluorophosphate (LiPOF2), adiponitrile (AND), and hexanetrionitrile (HTCN). The mass content of vinylene carbonate (VC) in the electrolyte is 0.5%, the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 1%, the mass content of lithium difluorophosphate (LiPOF2) in the electrolyte is 1%, the mass content of adiponitrile (AND) in the electrolyte is 0.5%, and the mass content of hexanetrionitrile (HTCN) in the electrolyte is 1.5%.

[0179] (3) Separator selection: The diaphragm is a composite diaphragm of base membrane and ceramic coating. The base membrane is a polyethylene base membrane with a thickness of 5μm. The two opposite surfaces of the base membrane are respectively provided with a ceramic coating with a thickness of 1μm. The ceramic coating is made of boehmite.

[0180] (4) Assembly: The positive electrode, separator and negative electrode are stacked and hot-pressed together and injected with electrolyte to form a lithium-ion safe battery.

[0181] The method for testing the resistivity of the positive electrode includes the following steps: Step 1: Preparation of Standard Samples Using a cutting die, cut multiple (e.g., four) identical pieces from the double-sided coated electrode sheet to be tested (along the MD and CD directions). A square sample.

[0182] Recording the original position of each sample on the electrode (e.g., head, middle, tail, left, right) is crucial for analyzing coating uniformity.

[0183] Weigh each sample using an electronic balance (m) and measure the thickness (d, averaged from multiple points) using a micrometer.

[0184] Step 2: Thoroughly dry the sample Place all samples in a constant temperature oven and bake under vacuum at 85°C for 6 hours (ensuring complete removal of moisture). After baking, allow the vacuum conditions to cool naturally to 25°C.

[0185] Note: During cooling and testing, it is essential to prevent the sample from coming into contact with air again, otherwise all previous efforts will be wasted.

[0186] Step 3: Set up and calibrate the four-probe tester Power on the four-probe tester and allow it to warm up. Calibrate according to the instrument's instruction manual (usually using a standard resistor). Set the appropriate test range (usually in the μΩ or mΩ range) and test current (either automatically selected by the instrument or set manually to avoid excessive current).

[0187] Step 4: Measurement and Recording Place the cooled sample on a flat test stage. Gently and vertically press the probes of the four-probe tester onto the surface of the positive electrode material coating on the sample. Record the measurements for each sample and correlate them with its original location, areal density / loading (g / m²), thickness, and other information.

[0188] The safety performance testing method for lithium-ion batteries includes the following steps: Phase 1: Preparation Place the heating chamber in a well-ventilated, explosion-proof area away from flammable materials. Operators must wear all necessary safety protective equipment. Cell pretreatment: At room temperature (25°C), charge the cells to 100% SOC using a standard charging regime (0.33C constant current charging to 4.45V, then constant voltage charging to a cutoff current of 0.05C). After charging, allow the cells to stand for 30 minutes to stabilize the voltage.

[0189] Equipment layout: Securely attach the thermocouples to the center of the battery surface using high-temperature Teflon tape. Place the battery with the positive and negative terminals facing upwards, suspended on a rack inside the thermal chamber, ensuring airflow around the battery and maintaining sufficient distance (typically >15cm) from the chamber walls and other battery cells. Connect all thermocouples to the data acquisition unit. Set up the camera, ensuring a clear view covering the battery cells.

[0190] Phase Two: Test Execution Setting parameters: Set the hot box temperature to... Start the heating chamber at a rate of 10°C / min and begin recording temperature and video. During the heat preservation phase: once the chamber temperature reaches 132°C, begin timing and maintain the temperature for 60 minutes (or the time specified in the standard). Closely monitor the battery surface temperature change curve on the data acquisition system.

[0191] Observation and monitoring: Continuously observe the battery through the observation window or camera for signs such as bulging, smoke, fire, explosion, or leakage. If there are no signs such as bulging, smoke, fire, explosion, or leakage, the battery is considered to have good safety performance and should be marked as Pass. If there are signs such as bulging, smoke, fire, explosion, or leakage, the battery is considered to have poor safety performance and should be marked as Fail.

[0192] Phase 3: Test Termination and Post-Processing Termination condition (test terminates if any one condition is met): Successful completion of 60 minutes of heat preservation.

[0193] The battery caught fire or exploded. A sharp rise in battery surface temperature was detected (characteristics of thermal runaway).

[0194] Cooling and cleaning: After the heat preservation is completed, turn off the heating and allow the hot box to cool naturally to room temperature (25°C) (usually takes several hours).

[0195] Only after confirming that the temperature inside the enclosure is below 50°C and there are no abnormalities (such as smoke) can you put on protective equipment and open the enclosure door. Carefully remove the failed battery cells and place them in an explosion-proof container or a designated disposal area.

[0196] The test results of positive electrode resistivity and lithium-ion battery safety performance are shown in Table 1.

[0197] Table 1

[0198] As can be seen from Table 1, compared with the case of full coating of oxide solid electrolyte in Comparative Example 2, the resistivity of the positive electrode sheet after the bottom-coated foil of each embodiment of this application is prepared is significantly reduced; while compared with Comparative Example 1 and Comparative Examples 3-4, although the resistivity of the positive electrode sheet prepared by the bottom-coated foil of each embodiment of this application and used in lithium-ion batteries is slightly reduced, the safety performance is improved. That is, the bottom-coated foil of the embodiments of this application prepared into positive electrode sheets and used in lithium-ion batteries has both excellent safety performance and conductivity.

[0199] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0200] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0201] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0202] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0203] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0204] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A base-coated foil material, characterized in that, include: Conductive substrate; A coating is provided on at least one surface of the conductive substrate in a discontinuously distributed manner, and the material of the coating includes an oxide solid electrolyte, a conductive agent, and a binder.

2. The base-coated foil according to claim 1, characterized in that, The conductive substrate has a coating on its surface, and the coating coverage is greater than 60% and less than 100%.

3. The base-coated foil material according to claim 1 or 2, characterized in that, The coating has a mesh structure; or... The coating comprises multiple sub-coatings, and the multiple sub-coatings have at least one of the following characteristics: (1) All of the multiple sub-coatings are strip-shaped; (2) The multiple sub-coatings are arranged at equal intervals; (3) The multiple sub-coatings are arranged in parallel to each other. (4) The plurality of sub-coatings are spaced apart along the first direction of the conductive substrate, and the angle between the first direction and the MD direction is 0-180°.

4. The base-coated foil according to any one of claims 1 to 3, characterized in that, The oxide solid electrolyte includes At least one of them; And / or, the mass ratio of the oxide solid electrolyte, the conductive agent, and the binder is (85-95):(0.5-3):(3-8).

5. The base-coated foil according to any one of claims 1 to 4, characterized in that, The coating material also includes a dispersant; And / or, the thickness of the coating on one side of the conductive substrate is less than 3µm.

6. A method for preparing a base-coated foil as described in any one of claims 1 to 5, characterized in that, include: Prepare a target slurry, the target slurry containing the material of the coating; The target slurry is formed on at least one surface of the conductive substrate, and the coating is obtained after curing.

7. The preparation method according to claim 6, characterized in that, Forming the target slurry on at least one surface of the conductive substrate includes: forming the target slurry on at least one surface of the conductive substrate using a roller transfer coating method; wherein the roller surface of the transfer roller used in the roller transfer coating has the discontinuously distributed grooves, the grooves being used to accommodate the target slurry.

8. The preparation method according to claim 7, characterized in that, The area of ​​the roller surface without the groove is a smooth area; And / or, the total area of ​​the grooves accounts for more than 60% and less than 100% of the total area of ​​the roller surface; And / or, the shape of the groove is comparable to the shape of the coating; And / or, the groove has one of the following structures: 1) It has a network structure; 2) Strip structures spaced circumferentially along the transfer roller, wherein the angle between the strip structures and the axis of the transfer roller is 0-180°.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The preparation of the target slurry includes: The oxide solid electrolyte, the conductive agent, and the binder are dried to obtain dried oxide solid electrolyte, dried conductive agent, and dried binder; The dried adhesive is dissolved in a portion of a solvent to obtain a glue solution; The dried conductive agent and the dried oxide solid electrolyte are sequentially dispersed in the adhesive solution to obtain a slurry; The viscosity of the slurry is adjusted to the target viscosity using the remaining solvent to obtain the target slurry.

10. The preparation method according to claim 9, characterized in that, The preparation of the target slurry also includes: Before dispersing the dried conductive agent and the dried oxide solid electrolyte in the adhesive solution in sequence, a dispersant is dispersed in the adhesive solution.

11. An apparatus for preparing a base-coated foil as described in any one of claims 1 to 5, characterized in that, include: A back roller is used to drive the conductive substrate to move. A transfer roller, disposed on one side of the back roller, is used to coat a target slurry onto at least one surface of the conductive substrate, the target slurry comprising the material of the coating; the roller surface of the transfer roller has the discontinuously distributed grooves for accommodating the target slurry.

12. The apparatus for preparing a base-coated foil according to claim 11, characterized in that, The area of ​​the roller surface without the groove is a smooth area; And / or, the total area of ​​the grooves accounts for more than 60% and less than 100% of the total area of ​​the roller surface; And / or, the shape of the groove is comparable to the shape of the coating; And / or, the groove has one of the following structures: 1) It has a network structure; 2) Strip structures spaced circumferentially along the transfer roller, wherein the angle between the strip structures and the axis of the transfer roller is 0-180°.

13. A positive electrode plate, characterized in that, It includes a positive electrode material layer and a base coating foil as described in any one of claims 1 to 5; the positive electrode material layer covers the surface of the base coating foil on which the coating is provided.

14. A battery comprising a positive electrode, a separator, and a negative electrode, characterized in that, The positive electrode is the positive electrode as described in claim 13.

15. A vehicle, characterized in that, Includes the battery as described in claim 14.

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