Coating device and battery production system

Abstract

The embodiment of the invention provides a coating device and a battery production system, and relates to the technical field of batteries. The coating device comprises a coating roller and a coating head, the coating roller is provided with a coating part, the edge of at least one side of the coating part in the axial direction is provided with a variable-diameter section, and the radial size of the variable-diameter section is larger than that of the other part of the coating part; the coating head is opposite to the coating roller in the radial direction of the coating roller, and an extrusion gap is formed between the coating head and the coating roller. According to the thinning principle, the characteristic that the larger the roller diameter of the edge of the coating roller is, the smaller the extrusion gap is, the thinning of the edge coating of the base material is achieved, the thickness and width of the coating of the edge of the base material can be more accurately controlled, and therefore the energy density of the base material after coating and the thickness process capacity of the edge thinning position are improved to a certain degree.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a coating device and a battery production system. Background Art

[0002] In the production process of battery devices, active materials need to be coated on the surface of the substrate by a coating device. Taking extrusion coating as an example, the coating edge needs to be thinned to solve the thick edge effect problem.

[0003] Related technologies use the flow resistance of the gasket in the coating head to reduce the edge flow and achieve the effect of edge thinning, but it still cannot meet the requirements of thinning width and thinning thickness. Therefore, how to effectively control the edge thinning width and thinning thickness is a research direction in battery technology. Summary of the invention

[0004] The present application provides a coating device and a battery production system, which can effectively control the edge thinning width and thinning thickness.

[0005] In the first aspect, an embodiment of the present application provides a coating device, comprising a coating roller and a coating head, wherein the coating roller is used to convey a substrate, the coating roller is provided with a coating portion, the coating portion is provided with a reducing section along at least one side edge of the axial direction of the coating roller, the radial minimum dimension of the reducing section is greater than the radial dimension of the rest of the coating portion; the coating head is used to coat slurry onto the substrate on the coating roller, the coating head is arranged opposite to the coating roller along the radial direction of the coating roller, and forms an extrusion gap with the coating roller.

[0006] By adopting the above technical scheme, the radial dimension of the edge of the coating part of the coating roller is enlarged to form a variable diameter section, so that the edge of the substrate of the coating roller can change the extrusion gap under the influence of the variable diameter section during extrusion coating, thereby realizing the coating thinning of the edge of the substrate. Compared with the related technology that uses the gasket blocking effect of the coating head to indirectly reduce the flow of the edge slurry, the thinning principle of the present application is to use the characteristic that the larger the roller diameter of the coating roller edge, the smaller the extrusion gap to achieve the thinning of the substrate edge coating, which can more accurately control the coating thickness and width of the substrate edge, thereby improving the energy density of the substrate after coating and the thickness process capability of the edge thinning to a certain extent.

[0007] In some embodiments of the present application, the diameter-changing section includes an annular protrusion surrounding an axial side edge of the coating portion along the circumference of the coating roller.

[0008] By adopting the above technical solution, the diameter-changing section is designed to include an annular protrusion, so that the diameter-changing section and the remaining area of ​​the coating portion form a stepped structure, thereby achieving a thinning process of the edge area of ​​the substrate after coating.

[0009] In some embodiments of the present application, there are multiple annular protrusions, and the multiple annular protrusions are arranged in sequence along the axial direction of the coating roller, and the radial dimensions of the multiple annular protrusions gradually increase in the direction away from the axial center of the coating portion.

[0010] By adopting the above technical solution, the variable diameter section is designed to include multiple annular protrusions, so that the variable diameter section forms a stepped structure. After thinning, the thinned area of ​​the substrate coating is closer to the edge coating thickness, which improves adhesion, reduces blistering and cracks, reduces overall weight, improves flexibility, optimizes material costs, enhances electrical performance, and better controls surface characteristics.

[0011] In some embodiments of the present application, the ratio of the protrusion height d of each annular protrusion relative to the coating portion to the coating thickness D formed by the substrate coating slurry is a preset value, and the preset value is greater than 0 and less than or equal to 1.

[0012] By adopting the above technical solution, the protruding height d of the annular protrusion on the coating portion is designed, and d / D is designed to a preset value, so that the thickness of the thinned edge of the substrate reaches a reasonable range, further improving the thickness process capability of the thinned edge of the substrate coating.

[0013] In some embodiments of the present application, along the radial direction of the coating roller, the difference in height between two adjacent annular protrusions protruding from the coating portion is 1-100 um.

[0014] By adopting the above technical solution, the height difference between two adjacent annular protrusions is set to 1-100um, so that the thickness of the edge thinning area after substrate coating is within a reasonable range, reducing the possibility that the thickness of the edge thinning area is too small and affects the energy density of subsequent battery cells.

[0015] In some embodiments of the present application, the difference in height between two adjacent annular protrusions protruding from the coating portion is 30-50 um.

[0016] By adopting the above technical solution, the height difference between two adjacent annular protrusions is set to 30-50um, which can make the thickness of the edge thinning area after substrate coating to be at a more reasonable size, further reducing the possibility that the thickness of the edge thinning area is too small and affects the energy density of subsequent battery cells.

[0017] In some embodiments of the present application, along the axial direction of the coating roller, the width of the annular protrusion is 0.1 mm-10 mm.

[0018] By adopting the above technical solution, the width of the annular protrusion is designed to be 0.1 mm-10 mm, so that the width of the edge thinning area after the substrate is coated can be in a reasonable size.

[0019] In some embodiments of the present application, along the axial direction of the coating roller, the width of the annular protrusion is 2 mm-5 mm.

[0020] By adopting the above technical solution, the width of the annular protrusion is designed to be 2mm-5mm. After the substrate is coated and thinned, the thinned structure formed by multiple annular protrusions makes the width of the edge thinning area of ​​the substrate after coating to be in a more reasonable size.

[0021] In some embodiments of the present application, the number of the annular protrusions is 1-10.

[0022] By adopting the above technical solution, the number of the annular protrusions is designed to be 1-10, which is convenient for processing.

[0023] In some embodiments of the present application, the number of the annular protrusions is 2-5.

[0024] By adopting the above technical solution, the number of annular protrusions is designed to be 2-5, which is more convenient for processing and can make the width of the edge thinning area after the substrate is coated smaller, further improving the energy density of the electrode after the substrate is coated.

[0025] In some embodiments of the present application, the radial dimension of the diameter-changing section gradually increases along a direction away from the axial center of the coating portion.

[0026] By adopting the above technical solution, the reducing section is designed as a gradual structure, and the radial dimension of the reducing section gradually increases in the direction away from the axial center of the coating portion. After thinning, the thinned area of ​​the substrate coating is closer to the edge and the coating thickness is smaller, which has the advantages of improving adhesion, reducing blistering and cracking, reducing overall weight, improving flexibility, optimizing material costs, improving electrical performance and better controlling surface characteristics.

[0027] In some embodiments of the present application, on the axial cross section of the coating roller, the two opposite sides of the diameter-changing section along the radial direction are both in the shape of an oblique line or a curve.

[0028] By adopting the above technical solution, the two opposite sides of the diameter-changing section along the radial direction are designed to be in an oblique line or curved shape, which not only plays a thinning role but also facilitates processing.

[0029] In some embodiments of the present application, the coating roller includes a plurality of blank portions, the blank portions and the coating portions are alternately arranged along the axial direction of the coating roller, and any coating portion is located in the interval between two blank portions, the radial dimension of the blank portion is larger than the minimum radial dimension of the coating portion, and the variable diameter section is used to connect the coating portion and the blank portion.

[0030] By adopting the above technical solution, a plurality of blank portions are provided on the coating roller, and the coating portion is located between two blank portions. The blank portion can reduce the possibility of the slurry leaking to the area that does not need to be coated, and can assist in controlling the coating area and thickness. In addition, it can also help balance the pressure distribution on the roller, thereby improving the coating effect and coating uniformity.

[0031] In some embodiments of the present application, the coating roller includes a rotating portion and a sleeve portion sleeved on the rotating portion, and the sleeve portion is provided with the coating portion and the blank portion.

[0032] By adopting the above technical solution, the coating roller is designed to include a rotating part and a sleeve part sleeved on the rotating part. The sleeve part can be replaced to coat substrates that do not meet the specifications, thereby improving the versatility of the coating roller.

[0033] In some embodiments of the present application, the sleeve portion includes a first sleeve and a second sleeve that are separated, the first sleeve is provided with the coating portion, and the second sleeve is provided with the blank portion.

[0034] By adopting the above technical solution, the sleeve connection part is designed as a separate first sleeve and a second sleeve. The first sleeve and the second sleeve of the required specifications can be installed on the rotating part as required to form a coating roller that meets the requirements, thereby further improving the versatility.

[0035] In some embodiments of the present application, the coating head and the coating roller form an extrusion gap, and the extrusion gap is used to determine the coating thickness of the substrate.

[0036] By adopting the above technical scheme, an extrusion gap is formed by using the coating head and the coating roller. After the slurry is extruded from the coating head, it is directly extruded and coated with the coating roller to form a coating on the surface of the substrate. The slurry on the edge of the substrate can be directly thinned by the variable diameter section of the coating roller and the coating head, thereby reducing the slurry casting time and improving the thinning effect.

[0037] In a second aspect, an embodiment of the present application provides a battery production system, comprising a coating device as described in any of the above technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of a coating device provided in some embodiments of the present application;

[0040] Figure 2 A schematic diagram of the structure of a coating roller provided in some embodiments of the present application;

[0041] Figure 3 for Figure 2 A magnified view of part a;

[0042] Figure 4 A schematic structural diagram of another coating roller provided in some embodiments of the present application;

[0043] Figure 5 for Figure 4 A magnified view of part b;

[0044] Figure 6 A schematic structural diagram of another coating roller provided in some embodiments of the present application;

[0045] Figure 7 for Figure 6 Enlarged view of part c;

[0046] Figure 8 Some embodiments of the present application provide a side view of a coating roller.

[0047] The reference numerals of the specific embodiments are as follows:

[0048] 100. Coating device;

[0049] 10. coating roller; 11. coating part; 111. diameter reducing section; 1111. first annular protrusion; 1112. second annular protrusion; 12. blank part; 13. rotating part; 14. sleeve part; 141. first sleeve; 142. second sleeve;

[0050] 20. Coating head;

[0051] 200, substrate;

[0052] X, axial; Y, radial. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0055] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0056] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0057] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0058] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0059] The term "plurality" used in the present application refers to two or more (including two).

[0060] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a battery box for encapsulating one or more battery cells. The battery box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0061] The battery cells mentioned in the embodiments of the present application may be lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells or magnesium-ion battery cells, etc., which are not limited in the embodiments of the present application. The battery cells may be cylindrical, flat, cuboid or other shapes, which are not limited in the embodiments of the present application.

[0062] The battery cell mentioned in the embodiments of the present application may include an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector; the positive current collector includes a positive electrode coating area and a positive electrode ear connected to the positive electrode coating area, the positive electrode coating area is coated with a positive electrode active material layer, and the positive electrode ear is not coated with a positive electrode active material layer. Taking a lithium-ion battery cell as an example, the material of the positive current collector can be aluminum, and the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, and the negative electrode coating area is coated with a negative electrode active material layer, and the negative electrode tab is not coated with a negative electrode active material layer. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The material of the separator can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc.

[0063] The battery cells described in the embodiments of the present application are suitable for batteries and electrical devices using batteries. Electrical devices may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0064] Below, the embodiments of the present application are described in detail.

[0065] At present, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0066] In the preparation process of the electrode sheets of the battery device, the extrusion coating method is often used. The coating process needs to thin the coating on the edge of the base layer to solve the thick edge effect. However, excessive thinning will affect the energy density of the battery cell. Mismatched thinning of the positive and negative electrode sheets will lead to lithium deposition, affecting the life and safety of the battery cell. How to effectively control the consistency of the edge thinning width and thinning thickness has become a problem that needs to be solved.

[0067] The relevant technology usually relies on the flow-blocking effect of the gasket in the coating head to reduce the flow at the edge. There is a certain gap between the coating head and the coating roller. After the slurry is extruded, it can be transferred to the substrate surface of the back roller through casting. However, since the slurry is a non-Newtonian fluid, the flow properties change with the shear force, and the thinning consistency is poor with the fluctuation of the slurry viscosity. In addition, the casting stroke and time of the slurry after flowing out are long, resulting in thinning effect components, making the width of the thinning area larger, which affects the volume energy density of the electrode and the N / P value of the battery cell, and further affects the cycle life and safety of the battery cell.

[0068] Therefore, how to better control the width and thickness of the thinned edge is an important issue in the production and processing of battery devices.

[0069] In view of this, the present application provides a technical solution, which utilizes the characteristic that the coating thickness of extrusion coating is positively correlated with the gap between the coating head and the coating roller, and provides a reducing section with a radially enlarged dimension at the edge of the coating portion of the coating roller, so that the reducing section can directly act on the coating edge area of ​​the substrate during extrusion coating, thereby better controlling the width and thickness of the thinned edge.

[0070] The following is combined with Figure 1-8 The coating device provided in the embodiment of the present application is introduced.

[0071] Combined with Figure 1 and 2 As shown, an embodiment of the present application provides a coating device 100, including a coating roller 10 and a coating head 20, the coating roller 10 is used to convey a substrate 200, the coating roller 10 is provided with a coating portion 11, and the coating portion 11 is provided with a reducing section 111 on at least one side edge along the axial direction X of the coating roller 10, and the radial Y dimension of the reducing section 111 is greater than the radial Y dimension of the remaining portion of the coating portion 11; the coating head 20 is used to provide coating slurry to the substrate 200 on the coating roller 10, and the coating head 20 is arranged opposite to the coating roller 10 along the radial direction Y of the coating roller 10, and forms an extrusion gap with the coating roller 10.

[0072] The coating roller 10 is used to receive the substrate 200 delivered by the substrate 200 unwinding device (not shown in the figure), and ensure that the substrate 200 smoothly enters the coating part 11. The coating roller 10 can be driven by a driving member such as a motor (not shown in the figure) to realize rotation around its own axial direction X, thereby moving and conveying the coated substrate 200.

[0073] The coating head 20 is connected to a feeding device (not shown in the figure), which may include a feeding pump, which may be a screw pump. The screw pump provides slurry to the coating head 20 and controls the coating amount by its own rotation speed.

[0074] The coating head 20 is used to provide slurry to the substrate 200 on the coating roller 10. The coating head 20 can cooperate with the coating roller 10 to form an extrusion gap. The substrate 200 is located in the extrusion gap, and the coating thickness of the substrate 200 is determined by the extrusion gap.

[0075] The coating roller 10 and the coating head 20 are arranged opposite to each other, and the two form an extrusion gap for extrusion coating. The slurry flowing out of the coating head 20 is applied on the substrate 200 through the common limiting extrusion action of the coating head 20 and the coating roller 10. The coating thickness of the substrate 200 is positively correlated with the extrusion gap formed by the coating head 20 and the coating roller 10 and the thickness of the coating. The smaller the extrusion gap, the smaller the coating thickness, and the larger the radial Y dimension of the edge of the coating roller 10, the smaller the extrusion gap formed with the extrusion head at the edge.

[0076] In addition, an extrusion gap is formed between the coating head 20 and the coating roller 10, and after the slurry is extruded from the coating head 20, it is directly extruded and coated with the coating roller 10 to form a coating on the surface of the substrate 200. The slurry on the edge of the substrate 200 can be directly thinned by the variable diameter section 111 of the coating roller 10 and the coating head 20, thereby reducing the slurry casting time and improving the thinning effect.

[0077] The coating portion 11 refers to the area of ​​the coating roller 10 facing the substrate 200 where the slurry needs to be coated. In some embodiments, the coating portion 11 can be understood as a section of the coating roller 10 along the axial direction X.

[0078] The variable diameter section 111 refers to a small section in which the radial Y dimension changes, and the radial Y dimension of the variable diameter section 111 is larger than the radial Y dimension of the rest of the coating portion 11, forming an annular flange structure, which means that the radial Y dimensions of all areas of the variable diameter section 111 along the axial direction X are larger than the radial Y dimensions of other parts of the coating portion 11 except the variable diameter section 111.

[0079] The radial Y dimension of the edge of the coating portion 11 of the coating roller 10 is enlarged to form a variable diameter section 111, so that the edge of the substrate 200 of the coating roller 10 can change the extrusion gap under the influence of the variable diameter section 111 during extrusion coating, thereby achieving coating thinning of the edge of the substrate 200.

[0080] Compared with the related art that uses the gasket blocking effect of the coating head 20 to indirectly reduce the flow of the edge slurry, the thinning principle of the present application is to use the characteristic that the larger the roller diameter at the edge of the coating roller 10, the smaller the extrusion gap to achieve thinning of the edge coating of the substrate 200. The coating thickness and width at the edge of the substrate 200 can be more accurately controlled, thereby improving the energy density of the substrate 200 after coating and the thickness process capability of the edge thinning to a certain extent.

[0081] After coating and thinning treatment using the coating device 100 of the present application, the width of the thinning area can be reduced from 15 mm to less than 5 mm, thereby improving the energy density of the electrode. In addition, the process capability (PPK) at the edge of the coating after coating is greater than 1.33, and the volume energy density of the electrode and the N / P value of the battery cell that affect the electrode can be reduced.

[0082] The above PPK is the process performance index, which is used to measure the ability of the process to meet the specification limits of the characteristic of interest. It compares the product characteristic fluctuation with the specification limit. The formula is:

[0083]

[0084] In the above formula, mu is the process mean, sigma is the process standard deviation, LSL is the lower specification limit, and USL is the upper specification limit.

[0085] In the N / P value of the battery cell, N stands for negative, representing the capacity of the negative electrode of the battery; P stands for positive, representing the capacity of the positive electrode of the battery. The N / P ratio of power lithium-ion batteries is generally about 1.06-1.10. A too high N / P ratio affects the energy density of the battery cell, but a too low N / P ratio can easily lead to lithium deposition in the negative electrode of the battery during the cycle. The deposition of lithium metal can easily form lithium dendrites, pierce the diaphragm, and ultimately affect the safety of the lithium battery.

[0086] Combined with Figure 2 and attached Figure 3 As shown, in some examples, optionally, the diameter-changing section 111 includes an annular protrusion surrounding an edge of one side of the coating portion 11 in the axial direction X along the circumference of the coating roller 10 .

[0087] The diameter-changing section 111 is designed to include an annular protrusion, so that the diameter-changing section 111 and the remaining area of ​​the coating portion 11 form a step-like structure, thereby achieving a thinning process of the edge area of ​​the substrate 200 after coating.

[0088] In some examples, optionally, there are multiple annular protrusions, and the multiple annular protrusions are arranged in sequence along the axial direction X of the coating roller 10, and the radial Y dimensions of the multiple annular protrusions gradually increase along the direction away from the axial direction X center of the coating portion 11.

[0089] The annular protrusion refers to a structure protruding along the circumference of the coating roller 10. The radial Y dimensions of the plurality of annular protrusions gradually increase, so that the variable diameter section 111 forms a stepped or approximately stepped structure on both sides of the axial X section.

[0090] The reducing section 111 is designed to include a plurality of annular protrusions, so that the reducing section 111 forms a stepped structure. The annular protrusions are larger in areas closer to the edge of the reducing section 111. After thinning, the coating thickness of the substrate 200 coating becomes smaller as the thinned area is closer to the edge. This has the advantages of improving adhesion, reducing blistering and cracking, reducing overall weight, increasing flexibility, optimizing material costs, improving electrical performance, and better controlling surface characteristics.

[0091] In addition, there is also a shorter casting time when the slurry is squeezed toward the edge by the extrusion gap. The above design can match the characteristics that the closer the slurry is to the edge, the longer the casting time and the worse the fluidity, which can improve the consistency of the edge thickness of the substrate 200 after coating to a certain extent.

[0092] In some examples, optionally, a ratio of a protruding height d of each annular protrusion relative to the coating portion to a coating thickness D formed by the substrate coating slurry is a preset value, and the preset value is greater than 0 and less than or equal to 1.

[0093] In some embodiments, the ratio of the protruding height d of each annular protrusion compared to the coating portion to the coating thickness D formed by the substrate coating slurry is equal to (1+k)*X, or can be understood as d=(1+k)*D*X.

[0094] (1+k)*X is greater than 0 and less than 1. In some embodiments, (1+k)*X may be greater than 0.06 and less than 0.45.

[0095] Wherein, k is the slurry shrinkage coefficient of the coating formed by coating the substrate 200 with the slurry, D is the thickness of the coating formed by coating the substrate 200 with the slurry, and X is the thinning coefficient.

[0096] The protruding height d of the annular protrusion on the coating portion 11 can be understood as the difference between the radial Y dimension of the annular protrusion and the radial Y dimension of other positions of the coating portion 11 .

[0097] The slurry shrinkage coefficient of the coating formed by coating the substrate 200 with the slurry is: k=thickness before drying / thickness after drying, which can be determined according to the specific slurry type, coating thickness and drying conditions, and can be 20%-50%.

[0098] The thinning coefficient (also called shrinkage coefficient or drying shrinkage coefficient) is an indicator used to describe the thickness change of the coating during the drying process. It is an empirical value in the relevant technology, usually 5%-30%, and is determined according to the thickness after drying. The smaller the thickness, the greater the thinning coefficient. In some embodiments, X = (thickness before drying-thickness after drying) / thickness before drying.

[0099] The two step structures formed by the first annular protrusion 1111 and the second annular protrusion 1112 in the figure are taken as an example to illustrate the above formula in combination with experimental data for better understanding.

[0100] Implementation Case 1:

[0101] Experimental conditions: for the iron-lithium slurry with a shrinkage coefficient of k=30%, the coating thickness D=230um formed by coating the substrate 200 with the slurry, X1 is selected as 25%, X2 is selected as 5%, the width of the first annular protrusion 1111 is 3mm, and the width of the second annular protrusion 1112 is 2mm.

[0102] The height of the first annular protrusion 1111 is calculated as follows: d1 = (1 + 30%) * 230 um * 25% = 81.25 um.

[0103] The height of the second annular protrusion 1112 is calculated as follows: d2 = (1 + 30%) * 230 umm * 5% = 16.25 um.

[0104] After obtaining the protruding heights of the first annular protrusion 1111 and the second annular protrusion 1112, for the convenience of processing, the protruding height d1 of the first annular protrusion 1111 is selected as 80 um, and the protruding height d2 of the second annular protrusion 1112 is selected as 15 um.

[0105] By using the first annular protrusion 1111 and the second annular protrusion 1112 with the above-mentioned protruding height, it is finally concluded that the thickness of the substrate 200 after thinning at 2 mm on the coated edge is 78% of the thickness of the edge body, there is no thick edge after coating, and the width after thinning is 6 mm. It can be seen that the width and thickness after thinning are better controlled.

[0106] Implementation Case 2:

[0107] Experimental conditions: for anode slurry with a shrinkage coefficient of k=40%, the coating thickness D=200um formed by coating the substrate 200 with the slurry, X1 is selected as 30%, X2 is selected as 10%, the width of the first annular protrusion 1111 is 3mm, and the width of the second annular protrusion 1112 is 2mm.

[0108] The protruding height of the first annular protrusion 1111 is calculated as: d1 = (1 + 40%) * 200 um * 30% = 84 um.

[0109] The protruding height of the second annular protrusion 1112 is calculated as: d2 = (1 + 30%) * 230un * 5% = 28um.

[0110] After obtaining the protruding heights of the first annular protrusion 1111 and the second annular protrusion 1112, for the convenience of processing, the protruding height d1 of the first annular protrusion 1111 is selected as 80um, and the protruding height d2 of the second annular protrusion 1112 is selected as 30um by rounding.

[0111] By using the first annular protrusion 1111 and the second annular protrusion 1112 with the above-mentioned protruding height, it is finally obtained that the thickness of the substrate 200 after thinning at 2mm on the coated edge is 70% of the thickness of the edge body, there is no thick edge after coating, and the width after thinning is about 8mm. It can be seen that the width and thickness after thinning are better controlled.

[0112] The above experiments show that when the slurry shrinkage coefficient and thinning coefficient are used to determine the size of the protruding height d of the annular protrusion, the thickness of the thinned edge of the substrate 200 can reach a reasonable range, further improving the process capability of the thickness of the thinned edge of the substrate 200 during coating.

[0113] In some examples, optionally, a height difference L between two adjacent annular protrusions protruding from the coating portion 11 is 1-100 um.

[0114] After determining the protruding height d of the annular protrusion using the slurry shrinkage coefficient and the thinning coefficient, this embodiment designs the height difference L between two adjacent annular protrusions protruding from the coating portion 11. L can be understood as the height difference between two adjacent steps.

[0115] For example, the difference L between the protrusion height d of the first annular protrusion 1111 and the second annular protrusion 1112 in the figure is 1um, 10um, 20um, 30um, 50um and 100um, etc., which are not listed one by one in this embodiment.

[0116] When the height difference L between two adjacent annular protrusions protruding from the coating portion 11 is 1-100um, the thickness of the edge thinning area of ​​the substrate 200 after coating can be within a reasonable range, reducing the possibility that the thickness of the edge thinning area is too small and affects the energy density of subsequent battery cells.

[0117] In addition, 1-100 um prevents the height difference between two adjacent steps from being too large, so that the thinned area can achieve a slow thinning transition along the width direction of the substrate 200 .

[0118] In some examples, optionally, a height difference L between two adjacent annular protrusions protruding from the coating portion 11 is 30-50 um.

[0119] In some embodiments, L can be 30um, 33um, 38um, 40um, 50um, etc., which are not listed one by one in this embodiment. For example, the radial Y dimension difference L between the first annular protrusion 1111 and the second annular protrusion 1112 in the figure can be any value mentioned above.

[0120] Compared with the wider 1-100um mentioned above, the radial Y dimension difference between two adjacent annular protrusions is 30-50um, which can make the thickness of the edge thinning area of ​​the substrate 200 after coating to be at a more reasonable size, further reducing the possibility that the thickness of the edge thinning area of ​​the substrate 200 is too small and affects the energy density of subsequent battery cells.

[0121] In some examples, optionally, along the axial direction X of the coating roller 10 , a width dimension H of the annular protrusion is 0.1 mm-10 mm.

[0122] The width and number of the annular protrusions determine the overall width of the subsequent thinning area of ​​the substrate 200. In some embodiments, the width H of the annular protrusions may be 0.1 mm, 1 mm, 3 mm, 5 mm, 10 mm, etc. For example, the width of the first annular protrusion 1111 may be 2 mm, and the width of the second annular protrusion 1112 may be 3 mm.

[0123] The width dimension H of the annular protrusion is designed to be 0.1 mm-10 mm, so that the width of the edge thinning area of ​​the substrate 200 after coating can be in a reasonable dimension.

[0124] In some examples, optionally, along the axial direction X of the coating roller 10 , a width dimension H of the annular protrusion is 2 mm-5 mm.

[0125] Compared with the above, H is designed to be 0.1mm-10mm, and the width dimension H of the annular protrusion is further designed to be 2mm-5mm. After the substrate 200 is coated and thinned, the thinning structure formed by multiple annular protrusions makes the width of the edge thinning area of ​​the substrate 200 after coating to be in a more reasonable size.

[0126] In some embodiments, the width dimension H of the annular protrusion is 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, etc. Correspondingly, the number of the annular protrusions can be 2-5.

[0127] In this way, the minimum width of the edge thinning area of ​​the substrate 200 after coating can be controlled within 5 mm, which can further improve the uniformity and consistency of the overall coating and help improve product quality.

[0128] In some examples, optionally, the number of the annular protrusions is 1-10.

[0129] The number of the annular protrusions can be 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, such as the two step structures formed by the first annular protrusion 1111 and the second annular protrusion 1112. In this embodiment, the number of the annular protrusions is designed to be 1-10, which is not only convenient for processing, but also can control the width of the thinning area.

[0130] In some examples, optionally, the number of the annular protrusions is 2-5.

[0131] Based on the above-mentioned number of annular protrusions of 1-10, the number of annular protrusions can further be 2, 3, 4 and five, which is more convenient for processing and can make the width of the edge thinning area of ​​the substrate 200 smaller after coating, further improving the energy density of the electrode after the substrate 200 is coated.

[0132] Combined with Figure 4-7 As shown, in some examples, optionally, along the direction away from the axial X center of the coating portion 11 , the radial Y dimension of the diameter-changing section 111 gradually increases.

[0133] Taking the example of each coating portion 11 in the figure having a reducing section 111 at both ends along the axial direction X, the radial Y dimension of each reducing section 111 gradually increases in the direction away from the axial center X of the coating portion 11, so that the reducing section 111 forms a gradual structure different from the above-mentioned step device.

[0134] The radial Y dimension of the end of the diameter-changing section 111 away from the axial X center of the coating portion 11 is the largest, and can be connected with other areas of the coating roller 10 (such as the blank portion 12 described below), so that the diameter-changing section 111 and other areas of the coating roller 10 have a smooth transition.

[0135] The variable diameter section 111 is designed to be a gradual structure, and the radial Y dimension of the variable diameter section 111 gradually increases in the direction away from the axial X center of the coating portion 11. The thinning of the edge coating of the substrate 200 is achieved by utilizing the characteristic that the larger the roller diameter at the edge of the coating roller 10, the smaller the extrusion gap. The coating thickness and width at the edge of the substrate 200 can be more accurately controlled, thereby improving the energy density of the substrate 200 after coating and the thickness process capability of the edge thinning to a certain extent.

[0136] In addition, the characteristic of the variable diameter section 111 gradually increasing in radial dimension toward the edge can to a certain extent match the characteristic that the closer to the edge the slurry is, the longer the casting time is and the worse the fluidity is, and can to a certain extent improve the consistency of the edge thickness of the substrate 200 after coating.

[0137] In some examples, optionally, in the axial X section of the coating roller 10 , opposite sides of the diameter-changing section 111 along the radial direction Y are both in an oblique line shape or a curved line shape.

[0138] The two modes of oblique line type or curved line type are convenient for processing while playing a thinning effect. Of course, the curved line structure is not limited to that shown in the figure, for example, the curved line can also be a curved line structure such as an arc or a wave, which is not listed one by one in this embodiment.

[0139] See attached Figure 4 and attached Figure 5 As shown, in the axial X section of the coating roller 10 , the two opposite sides of the diameter-changing section 111 along the radial direction Y are both oblique lines, so that the diameter-changing section 111 forms a truncated cone structure.

[0140] Combined with Figure 6 and attached Figure 7 As shown, in the axial X section of the coating roller 10 , the two opposite sides of the diameter-changing section 111 along the radial direction Y are both curved, so that the diameter-changing section 111 forms a structure approximately in the shape of a truncated cone.

[0141] Combined with Figure 2 , 4 As shown in Figure 6, in some examples, optionally, the coating roller 10 includes a plurality of blank portions 12, the blank portions 12 and the coating portions 11 are alternately arranged along the axial direction X of the coating roller 10, and any coating portion 11 is located in the interval between two blank portions 12, the radial Y dimension of the blank portion 12 is greater than the radial Y dimension of the coating portion 11, and the variable diameter section 111 is used to connect the coating portion 11 and the blank portion 12.

[0142] The radial Y dimension of the blank portion 12 is greater than the radial Y dimension of the coating portion 11 . It can be understood that a groove is machined on the coating roller 10 , the groove is the coating portion 11 , and the area adjacent to the groove along the axial direction X is the blank portion 12 .

[0143] The diameter-reducing section 111 is used to connect the blank portion 12 and the coating portion 11. Figure 4-7 When the blank portion 12 and the coating portion 11 are in an oblique line or curved shape, a smooth transition structure can be formed between the blank portion 12 and the coating portion 11.

[0144] The blank portion 12 limits the range of slurry coating. Specifically, by adjusting the length of the blank portion 12, the coating area and thickness can be controlled to meet the needs. In addition, the blank portion 12 can reduce the possibility of slurry leaking to areas that do not need to be coated, and maintain the precise positioning of the coating. Furthermore, the blank portion 12 also helps to balance the pressure distribution on the coating roller 10, improving the coating effect and coating uniformity.

[0145] Combined with Figure 2 and attached Figure 8 As shown, in some examples, optionally, the coating roller 10 includes a rotating portion 13 and a sleeve portion 14 sleeved on the rotating portion 13 , and the sleeve portion 14 is provided with a coating portion 11 and a blank portion 12 .

[0146] The rotating part 13 can be a cylindrical structure, and the sleeve part 14 as a whole can be a tubular structure with openings at both ends in the axial direction X. When the sleeve part 14 and the rotating part 13 are assembled, the sleeve part 14 can be directly sleeved on the rotating part 13, or assisted by other mechanical connection methods (adhesion, clamping, threaded connection, etc.).

[0147] The coating roller 10 is designed to include a rotating portion 13 and a sleeve portion 14 sleeved on the rotating portion 13 . The sleeve portion 14 can be replaced to coat substrates 200 that do not meet the specifications, thereby improving the versatility of the coating roller 10 .

[0148] In some examples, optionally, the sleeve portion 14 includes a first sleeve 141 and a second sleeve 142 that are separated, the first sleeve 141 is provided with a coating portion 11 , and the second sleeve 142 is provided with a blank portion 12 .

[0149] The first sleeve 141 and the second sleeve 142 can both be cylindrical structures with openings at both ends in the axial direction X, and can be mounted on the rotating part 13 by sleeve connection or the like.

[0150] When it is necessary to coat substrates 200 of different specifications, the first sleeves 141 and the second sleeves 142 of corresponding numbers and specifications can be selected according to the requirements to form a coating roller 10 that meets the requirements, thereby further improving the versatility of the coating roller 10.

[0151] Finally, please see the attached Figure 1-8As shown, the embodiment of the present application provides a coating device 100, including a coating roller 10 and a coating head 20. The coating roller 10 is used to convey a substrate 200. The coating roller 10 is provided with a coating portion 11. The coating portion 11 is provided with a diameter reducing section 111 on at least one side edge along the axial direction X of the coating roller 10. The radial Y dimension of the diameter reducing section 111 is greater than the radial Y dimension of the rest of the coating portion 11. The coating head 20 is used to provide coating slurry to the substrate 200 on the coating roller 10. The coating head 20 is arranged opposite to the coating roller 10 along the radial direction Y of the coating roller 10, and forms an extrusion gap with the coating roller 10. The extrusion gap is used to determine the coating thickness of the substrate 200. The diameter reducing section 111 includes an annular protrusion surrounding the edge of one side of the axial direction X of the coating portion 11 along the circumference of the coating roller 10. There are multiple annular protrusions, and the multiple annular protrusions are arranged in sequence along the axial direction X of the coating roller 10. In the direction away from the axial direction X center of the coating part 11, the radial Y dimensions of the multiple annular protrusions gradually increase. The ratio of the protruding height d of each annular protrusion compared to the coating part to the coating thickness D formed by the substrate coating slurry is a preset value, and the preset value is greater than 0 and less than or equal to 1. The radial Y dimension difference between two adjacent annular protrusions is 1-100um. The radial Y dimension difference between two adjacent annular protrusions is 30-50um. Along the axial direction X of the coating roller 10, the width dimension of the annular protrusion is 0.1mm-10mm. Along the axial direction X of the coating roller 10, the width dimension of the annular protrusion is 2mm-5mm. The number of annular protrusions is 1-10. The number of annular protrusions is 2-5. In the direction away from the axial direction X center of the coating part 11, the radial Y dimension of the variable diameter section 111 gradually increases. On the axial X section of the coating roller 10, the two opposite sides of the diameter-changing section 111 along the radial direction Y are both oblique or curved. The coating roller 10 includes a plurality of blank portions 12, the blank portions 12 and the coating portion 11 are alternately arranged along the axial direction X of the coating roller 10, and any coating portion 11 is located in the interval between two blank portions 12, the radial Y dimension of the blank portion 12 is larger than the radial Y dimension of the coating portion 11, and the diameter-changing section 111 is used to connect the coating portion 11 and the blank portion 12. The coating roller 10 includes a rotating portion 13 and a sleeve portion 14 sleeved on the rotating portion 13, the sleeve portion 14 is provided with the coating portion 11 and the blank portion 12. The sleeve portion 14 includes a first sleeve 141 and a second sleeve 142 which are separated, the first sleeve 141 is provided with the coating portion 11, and the second sleeve 142 is provided with the blank portion 12. The coating head 20 and the coating roller 10 form an extrusion gap, and the extrusion gap is used to determine the coating thickness of the substrate 200 .

[0152] In a second aspect, an embodiment of the present application provides a battery production system, including a coating device 100 of the above technical solution.

[0153] In addition to the coating device 100 , the battery production system may also include a slurry production device and a drying device (not shown in the figure), wherein the slurry production device is used to produce slurry and provide slurry to the feeding device, and the drying device is used to dry the substrate 200 after being coated by the coating device 100 .

[0154] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, but these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A coating device, characterized in that: include: A coating roller, used for conveying a substrate, the coating roller is provided with a coating portion, the coating portion is provided with a diameter-reducing section along at least one side edge of the axial direction of the coating roller, and the minimum radial dimension of the diameter-reducing section is greater than the radial dimension of the remaining portion of the coating portion; as well as The coating head is used for coating the slurry onto the substrate on the coating roller. The coating head is arranged opposite to the coating roller along the radial direction of the coating roller and forms an extrusion gap with the coating roller.

2. The coating device according to claim 1, characterized in that: The diameter-changing section comprises an annular protrusion surrounding an axial side edge of the coating portion along the circumference of the coating roller.

3. The coating device according to claim 2, characterized in that: There are multiple annular protrusions, which are arranged in sequence along the axial direction of the coating roller, and the radial dimensions of the multiple annular protrusions gradually increase in a direction away from the axial center of the coating portion.

4. The coating device according to claim 3, characterized in that: The ratio of the protruding height d of each annular protrusion relative to the coating portion to the coating thickness D formed by the substrate coating slurry is a preset value, and the preset value is greater than 0 and less than or equal to 1.

5. The coating device according to claim 4, characterized in that: Along the radial direction of the coating roller, the difference in height between two adjacent annular protrusions protruding from the coating portion is 1-100 um.

6. The coating device according to claim 5, characterized in that: The difference in height between two adjacent annular protrusions protruding from the coating portion is 30-50 um.

7. The coating device according to claim 3, characterized in that: Along the axial direction of the coating roller, the width of the annular protrusion is 0.1 mm-10 mm.

8. The coating device according to claim 7, characterized in that: Along the axial direction of the coating roller, the width of the annular protrusion is 2mm-5mm.

9. The coating device according to claim 2, characterized in that: The number of the annular protrusions is 1-10.

10. The coating device according to claim 9, characterized in that: The number of the annular protrusions is 2-5.

11. The coating device according to claim 1, characterized in that: Along the direction away from the axial center of the coating portion, the radial dimension of the diameter-changing section gradually increases.

12. The coating device according to claim 11, characterized in that: On the axial cross section of the coating roller, opposite sides of the diameter-changing section along the radial direction are both in an oblique line shape or a curved line shape.

13. The coating device according to any one of claims 1 to 12, characterized in that: The coating roller includes a plurality of blank portions, wherein the blank portions and the coating portions are alternately arranged along the axial direction of the coating roller, and any coating portion is located in the interval between two blank portions, the radial dimension of the blank portion is larger than the minimum radial dimension of the coating portion, and the variable diameter section is used to connect the coating portion and the blank portion.

14. The coating device according to claim 13, characterized in that: The coating roller comprises a rotating part and a sleeve part sleeved on the rotating part, and the sleeve part is provided with the coating part and the blank part.

15. The coating device according to claim 14, characterized in that: The sleeve connection portion includes a first sleeve and a second sleeve that are separated. The first sleeve is provided with the coating portion, and the second sleeve is provided with the blank portion.

16. A battery production system, characterized in that: Comprising a coating device as described in any one of claims 1-15.

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