Coating gasket and coating device

Abstract

The utility model discloses a coating gasket and a coating device. The coating gasket comprises a gasket body, a first flow baffle and a second flow baffle, the first flow baffle and the second flow baffle are connected to the two opposite ends of the gasket body, and the ends, facing each other, of the first flow baffle and the second flow baffle are each provided with a chamfering area so as to form a flaring-type discharging opening; the point, closest to the gasket body, of the projection of the chamfering area in the thickness direction of the gasket body is A, the point farthest from the projection of the chamfering area in the thickness direction of the gasket body is B, the vertical distance from A to B in the length direction parallel to the gasket body is a, and the vertical distance from B to A in the width direction parallel to the gasket body is b, egt; b. According to the utility model, the problems that the slurry at the edge of the pole piece is bulged and the thinning depth of the formed thinning area exceeds a design value in the coating process can be at least solved.

Description

Technical Field

[0001] The utility model relates to the field of lithium-ion battery coating, in particular to a coating gasket and a coating device. Background Art

[0002] With the rapid development of social economy, lithium-ion batteries have the advantages of high voltage, long life, good safety, high specific energy, environmental protection, etc., making lithium-ion batteries widely used in various fields. At the same time, the demand for increasing the capacity of lithium-ion batteries is also increasing day by day. In this context, silicon-containing anodes gradually replace traditional pure graphite anodes. Extrusion coating is one of the main coating methods in the lithium battery industry. In the extrusion coating process, the slurry is transported to the slit of the coating die head and extruded, coated on the surface of the substrate, and then dried in an oven to obtain a coated product.

[0003] In the manufacturing process of lithium-ion batteries, the quality of the electrode coating process has a great impact on the difficulty and quality of the subsequent production process of lithium-ion batteries. Summary of the Utility Model

[0004] In view of the above problems, the utility model provides a coating gasket and a coating device, which at least solve the problems of slurry bulging at the edge of the electrode and the thinning depth of the formed thinning area exceeding the design value during the coating process.

[0005] The technical solution of the utility model is realized as follows:

[0006] According to one aspect of the utility model, a coating gasket is provided, which includes: a gasket body, a first baffle and a second baffle connected to opposite ends of the gasket body, and chamfered areas are respectively arranged at the ends of the first baffle and the second baffle facing each other to together form a flared discharge port; wherein, the point closest to the gasket body in the projection of the chamfered area in the thickness direction of the gasket body is A and the farthest point is B, the distance from A to B along the width direction of the gasket body is a, and the distance from B to A along the length direction of the gasket body is b, and a > b.

[0007] Preferably, the chamfered area is a round chamfer, and the radius of the round chamfer is R, R 2 -a 2 =(R - b)2.

[0008] Preferably, the chamfered area is an inclined chamfer, and the chamfered surface of the inclined chamfer is a flat inclined surface.

[0009] Preferably, a plurality of partition plates spaced apart from each other are further provided on the gasket body, and the plurality of partition plates are disposed between the first baffle plate and the second baffle plate; chamfered areas are provided at the ends of each partition plate to form a plurality of flared sub-outlet ports together with the chamfered areas of the first baffle plate and the chamfered areas of the second baffle plate.

[0010] Preferably, the first baffle plate and the second baffle plate are vertical plates.

[0011] Preferably, the first baffle plate includes a first vertical portion connected to one end of the gasket body and a first horizontal portion connected to the side of the first vertical portion away from the gasket body; the second baffle plate includes a second vertical portion connected to one end of the gasket body and a second horizontal portion connected to the side of the second vertical portion away from the gasket body, and the chamfered areas are respectively disposed at the ends of the first horizontal portion and the second horizontal portion.

[0012] Preferably, the gasket body, the first baffle plate and the second baffle plate are an integral plate member.

[0013] Preferably, the gasket body, the first baffle plate and the second baffle plate together form a C-shaped plate member.

[0014] According to another aspect of the present invention, a coating device is further provided, including the coating gasket described above.

[0015] The beneficial effects of the above technical solutions include:

[0016] For the coating gasket and the coating device of the present invention, by designing the outlet of the coating gasket as a flare formed by a chamfered area, and setting the chamfered areas on the coating gasket to satisfy that the distance a determining the longitudinal distribution of the slurry > the distance b determining the transverse distribution of the slurry, the transverse distribution and transverse flow rate of the slurry at the chamfered area are reduced, at least in the process of coating the silicon-containing system negative electrode sheet, the slurry does not bulge at the edge of the negative electrode sheet during coating, and the thinning depth of the thinning area of the negative electrode sheet does not exceed the design value. Therefore, the capacity of the negative electrode thinning area is ensured, and the phenomenon of lithium precipitation during full charge of the battery is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 It is a top view of an embodiment of the coating gasket of the present invention.

[0019] Figure 2 is a top view according to another embodiment of the present utility model.

[0020] Figure 3 is a top view according to yet another embodiment of the present utility model. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0022] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements will be described below to simplify the present utility model. Of course, these are only examples and are not intended to limit the present utility model. Moreover, the present utility model may repeat reference numerals and / or letters in various examples. This repetition is only for the sake of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0023] In addition, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in conjunction with the embodiments. It should be understood that the specific structures shown in the drawings are only for illustrative purposes and are not intended to limit the present application. Expressions indicating directions such as the X direction and the Y direction for explaining the operations and structures of the components of the coating gasket and the coating device in the present embodiment are not absolute but relative. When describing a specific figure, other structures not shown in the figure may be provided according to actual needs and are not intended to limit the present application.

[0024] In the lithium battery manufacturing process, the quality of the electrode coating process directly determines the quality of the lithium battery. In the process of the silicon-containing system negative electrode coating process, the viscosity of the negative electrode slurry in the silicon-containing system is relatively high, and the solid content is relatively low. The demand for gaskets is different from that of the traditional pure silicon system. If the existing gaskets are continued to be used, the slurry at the edges of the silicon-containing system negative electrode is likely to bulge during coating, and the subsequent process production cannot be carried out smoothly. The thickness at both edges of the diaphragm not only affects the subsequent manufacturing process of the electrode, but also strengthening the thinning effect will cause the weight of the edge slurry to decrease beyond the design limit, resulting in lithium deposition during the full charge of the battery cell, serious capacity attenuation, and even causing the battery cell to smoke and catch fire, affecting the performance and safety of the battery.

[0025] Based on this, an embodiment of the present application provides a coating gasket. By designing the discharge port of the coating gasket as a flared opening, and the size satisfying that the chamfered area a of the coating gasket is greater than b, it can at least solve the problems that during the coating process of the silicon-containing system anode electrode sheet, slurry bulging occurs at the edge of the electrode sheet during coating, the thickness of the thinned area generated at the edge of the film sheet of the anode electrode sheet is too low, and the thinning of the thinned area of the anode electrode sheet exceeds the design value, resulting in lithium plating during full charge of the battery. The following will be elaborated with specific embodiments.

[0026] As Figures 1 to 3 shown, the coating gasket includes: a gasket body 1, a first baffle 2 and a second baffle 3, and a chamfered area 4 is provided on the first baffle 2 and the second baffle 3. Specifically, the first baffle 2 and the second baffle 3 are connected to opposite ends of the gasket body 1, and chamfered areas 4 are respectively provided at the ends of the first baffle 2 and the second baffle 3 facing each other to together form a discharge port 6 in a flared form. To further illustrate the chamfered area, for example, in Figure 1 it, the point closest to the gasket body 1 in the perpendicular distance of the projection of the chamfered area 4 in the thickness direction (perpendicular to the width direction Y and the length direction X) of the gasket body 1 is A, and the point farthest from the gasket body 1 in the perpendicular distance of the projection is B. The distance from A to B along the width direction Y parallel to the gasket body 1 is a, and the distance from B to A along the length direction X parallel to the gasket body 1 is b, and a > b.

[0027] The gasket body 1 can be a rectangular plate. At opposite ends in its length direction X, the first baffle 2, the second baffle 3 and the gasket body 1 enclose a region for the slurry flow of the silicon-containing system anode. And the first baffle 2, the second baffle 3 and the gasket body 1 are integral plate members, that is, they can be integrally formed without the need for assembly, and the structure is more stable. The slurry of the silicon-containing system anode flows away from the gasket body 1 and flows out from the discharge port 6 formed at the ends of the first baffle 2 and the second baffle 3.

[0028] Due to the existence of the chamfered area 4, the slurry of the silicon-containing negative electrode system not only flows longitudinally but also transversely after passing through the chamfered area 4. Therefore, the flow velocity decreases longitudinally, and as a result, the weight of the slurry coated on the edge of the electrode decreases, creating a thinning area at the edge of the negative electrode sheet. b determines the transverse distribution of the slurry at the chamfered area 4, and a determines the longitudinal distribution of the slurry at the chamfered area 4. Since b < a, the transverse distribution of the slurry is small, and the transverse flow velocity is also small. At least during the coating process of the silicon-containing negative electrode sheet, no transverse bulging of the slurry occurs at the edge of the electrode sheet, and it can solve the problems of the thickness of the thinning area generated at the edge of the membrane of the silicon-containing negative electrode sheet being too low and the thinning depth of the thinning area of the negative electrode sheet exceeding the design value, resulting in insufficient active material and lithium plating during full charge of the battery. The thickness of the thinning area of the negative electrode sheet formed by using the gasket of the embodiment of the present application will not be too low. Therefore, the negative electrode capacity of the negative electrode thinning area will not be too small, improving the volumetric energy density of the battery cell. Therefore, lithium plating can be prevented. The existence of the chamfered area 4 also makes the formed thinning area have a relatively high thickness consistency and a relatively smooth thinning transition, improving the quality of the produced battery.

[0029] In comparison, if b > a, when the slurry of the silicon-containing negative electrode system passes through the chamfered area 4, a small part of the slurry of the silicon-containing negative electrode system will show epitaxy, resulting in the thickness of the thinning area generated at the edge of the membrane of the negative electrode sheet being too low, the thinning depth of the thinning area of the negative electrode sheet exceeding the design value, and the negative electrode capacity of the negative electrode thinning area being small, leading to lithium plating during full charge of the battery.

[0030] As Figure 1 shown, in some embodiments, the chamfered area 4 can be a circular chamfer 14, and the radius of the circular chamfer 14 is R, where R 2 -a 2 = (R - b)2.

[0031] During coating, the slurry of the silicon-containing negative electrode system flows away from the gasket body 1 towards the discharge port 6. Due to the existence of the circular chamfer 14, after the slurry of the silicon-containing negative electrode system passes through the circular chamfer 14, a thinning area will be generated at the edge of the negative electrode sheet membrane. The circular chamfer 14 can be a part of an arc, and the radius R of the arc can be changed according to the parameters of the silicon-containing negative electrode system material, but it must satisfy R 2 -a 2 = (R - b)2, and a > b. For the circular chamfer 14 that satisfies the conditions of R, a, and b, to a certain extent, it can enhance the containment effect of the chamfered area 4 on the bulging of the slurry at the edge of the electrode and the excessive thinning of the thinning area of the electrode sheet. At least during the coating process of the silicon-containing negative electrode sheet, no bulging of the slurry occurs at the edge of the electrode sheet, and the thinning depth of the thinning area of the negative electrode sheet does not exceed the design value, avoiding the situation of lithium plating during full charge of the battery.

[0032] Although the chamfered region of the first baffle 2 in the above reference Figure 1 describes the shape of the chamfered region and the relationship between R, a, and b, the shape of the chamfered region of the second baffle 3 and the relationship between R, a, and b and their definitions are the same as those of the first baffle 2, so they will not be elaborated here. However, it can be understood that although it is preferably that the sizes of R, a, and b of the chamfered regions of the first baffle 2 and the second baffle 3 can be the same, they can also be different, as long as they are constrained by R 2 -a 2 =(R - b)2, and a > b, the above effects can be achieved.

[0033] As Figure 2 , Figure 3 shown, in some embodiments, the chamfered region 4 can be an inclined chamfer 16, and the chamfered surface of the inclined chamfer 16 can be a flat inclined surface. The inclined chamfer 16 needs to satisfy a > b, and the aforementioned definitions of a and b also apply. In addition, the chamfered region 4 can be a stepped shape, that is, the chamfered region 4 includes multiple steps from point A to point B, and a > b, which can prevent the slurry from bulging at the edge of the silicon-containing system negative electrode sheet during the coating process of the silicon-containing system negative electrode sheet, and make the thinning depth of the thinning area of the negative electrode sheet not exceed the design value, avoiding the situation of lithium precipitation when the battery is fully charged. When the chamfered region 4 is Figure 1 the circular arc shape shown, Figures 2 to 3 the inclined / sloped shape shown, and multiple embodiments of the stepped shape, the circular arc-shaped chamfered region 4 is more friendly to the flow of the slurry as a fluid, and the formed thinning area is also smoother and more uniform.

[0034] In some embodiments, the first baffle 2 and the second baffle 3 can be vertical plates as Figure 1 shown, that is, there is no first horizontal portion 9 and second horizontal portion 10 as Figure 2 and Figure 3 shown. The slurry is not blocked in the flow direction and flows more smoothly. In other embodiments, for example Figure 2 shown, the first baffle 2 includes a first vertical portion 7 connected to one end of the gasket body 1 and a first horizontal portion 9 connected to the side of the first vertical portion 7 away from the gasket body 1. Further, it can be seen that the second baffle 3 includes a second vertical portion 8 connected to one end of the gasket body 1 and a second horizontal portion 10 connected to the side of the second vertical portion 8 away from the gasket body 1, wherein the chamfered region 4 is respectively provided at the ends of the first horizontal portion 9 and the second horizontal portion 10. The first horizontal portion 9 and the second horizontal portion 10 form blocks when the slurry flows. When the slurry flows through the discharge port 6, under the blocking action of the first horizontal portion 9 and the second horizontal portion 10, the slurry flow rate at both sides of the discharge port 6 will decrease, which helps to form the thinning areas at both sides of the electrode sheet.

[0035] Continuing, the first vertical portion 7 and the second vertical portion 8 can be rectangular plates. A groove can be formed between the first vertical portion 7, the first horizontal portion 9 and the gasket body 1, and a groove can be formed between the second vertical portion 8, the second horizontal portion 10 and the gasket body 1. The slurry of the silicon-containing negative electrode system flows away from the gasket body 1 and flows out from the discharge port 6 formed at the ends of the first baffle 2 and the second baffle 3. During coating, the slurry of the silicon-containing negative electrode system flows in the direction away from the gasket body 1 towards the discharge port 6. Due to the existence of the chamfer 16, after the slurry of the silicon-containing negative electrode system passes through the chamfer 16, a thinning area will be generated at the edge of the negative electrode sheet film, at least ensuring that during the coating process of the silicon-containing negative electrode sheet, there is no bulging of the slurry at the edge of the sheet. Preferably, for example Figure 2 As shown, since the first baffle 2 and the second baffle 3 include the first horizontal portion 9 and the second horizontal portion 10 that serve as stoppers to help form the thinning area, the gasket body 1, the first baffle 2 and the second baffle 3 can together form a C-shaped plate member.

[0036] As Figure 3 shown, in some embodiments, a plurality of partition plates 11 spaced apart from each other are further provided on the gasket body 1, and the plurality of partition plates 11 are provided between the first baffle 2 and the second baffle 3. A chamfered area 4 is provided at the end of each partition plate 11 to together with the chamfered area 4 of the first baffle 2 and the chamfered area 4 of the second baffle 3 to form a plurality of flared sub-discharge ports 12. Obviously, it can be understood from the examples in the figure that the chamfered area 4 of the first baffle 2, the chamfered area 4 of the second baffle 3 and the plurality of partition plates 11 together form 4 sub-discharge ports 12, that is, it can be understood that one discharge port 6 is divided into 4 sub-discharge ports 12, and 4 negative electrode sheets can be coated simultaneously. It can be understood that the embodiments of the present application Figure 1 and Figure 2 coat a single negative electrode sheet, and the embodiments of the present application are not limited to the number of coated sheets, and the number of partition plates 11 and the chamfered area 4 thereon can be adjusted accordingly according to the required number of sheets.

[0037] The chamfered area 4 provided at the end of each partition plate 11 can be the chamfer 16 described above( Figure 3 (not shown in the figure), or can be the rounded chamfer 14 described above. The chamfered area 4 at the end of each partition plate 11 also needs to satisfy a>b, and the definitions of a and b are the same as those described above.

[0038] To Figure 3For example, when multiple silicon-containing system anode sheets need to be coated, the slurry of the silicon-containing system anode is extruded from the coating device. The side edges of two adjacent plates within a single sub-outlet 12 and the side edge of the gasket body 1 close to the outlet 6 form a flow space for the slurry. When the slurry of the silicon-containing system anode flows through the outwardly expanding chamfered area 4, multiple thinning areas will be generated in the coated film sheet (which can also be called the active material layer); and because each chamfered area 4 satisfies a > b, when the slurry of the silicon-containing system anode passes through the chamfered area 4, there will be no epitaxial phenomenon of the slurry of the silicon-containing system anode. At least during the coating process of the silicon-containing system anode sheet, there will be no phenomena such as slurry bulging at the edge of the anode sheet and too low thickness of the thinning area during the coating of the silicon-containing system anode sheet. The thinning depth of the thinning area of the anode sheet will not exceed the design value, thus avoiding the phenomenon of lithium deposition during full charge of the battery. At the end of the coating process of the silicon-containing system anode sheet, by cutting the anode sheet with multiple thinning areas, multiple silicon-containing system anode sheets with thinning areas where the thinning depth does not exceed the design value can be obtained at the end of one process.

[0039] According to some embodiments of the present application, the embodiments of the present application further provide a coating device, including a coating die head and the coating gasket in the previous embodiments. The coating gasket is assembled in the coating die head, which will not be elaborated here.

[0040] The so-called thinning area is the part where the thickness of the film edge of the anode sheet (the film edge in the width direction of the anode sheet) is thinned. Take the average value of the thickness of the active material layer of the anode sheet along the length direction of the anode sheet from the edge of the thinning area for 20 mm to 50 mm. The difference between the lowest point of the thickness of the thinning area and the average value is used as the thinning depth. By designing the outlet of the coating gasket to be flared and satisfying a > b at the chamfered area 4 of the coating gasket in the embodiments of the present application, at least for a slurry of a silicon-containing system anode with a viscosity of 5000 - 10000 m·Pas, the thinning depth of the anode sheet after coating and drying can be improved from 10 μm to within 5 μm at a coating speed of 30 - 60 m / min. The range of the thinning area is improved from 12 μm to 3.73 μm, and the standard deviation of the thinning area is improved from 2.23 to 1.24, and there is no edge bulging phenomenon. At the same time, since the thinning depth of the thinning area is controlled not to exceed the design value, it is possible to prevent lithium deposition and serious capacity attenuation during full charge of the battery.

[0041] The above are only the preferred embodiments of the present utility model and are not used to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A coated gasket, characterized in that: include: A gasket body, and a first baffle plate and a second baffle plate connected to opposite ends of the gasket body, wherein the first baffle plate and the second baffle plate are respectively provided with chamfered areas at one end facing each other to form a flared discharge port together; Among them, the projection of the chamfered area in the thickness direction of the gasket body is perpendicular to the point A that is closest to the gasket body and the point B that is farthest from the gasket body, the distance from A to B along the width direction parallel to the gasket body is a, and the distance from B to A along the length direction parallel to the gasket body is b, and a>b.

2. The coated gasket according to claim 1, characterized in that: The chamfered area is a round chamfer, and the radius of the round chamfer is R, R 2 -a 2 =(Rb)2.

3. The coated gasket according to claim 1, characterized in that: The chamfered area is an oblique chamfer, and the chamfered surface of the oblique chamfer is a flat inclined surface.

4. The coated gasket according to claim 3, characterized in that: The gasket body is also provided with a plurality of partition plates spaced apart from each other, and the plurality of partition plates are arranged between the first baffle plate and the second baffle plate. The chamfered area is provided at the end of each partition plate to form a plurality of flared sub-discharging ports together with the chamfered area of ​​the first baffle plate and the chamfered area of ​​the second baffle plate.

5. The coated gasket according to claim 2, characterized in that: The first baffle plate and the second baffle plate are vertical plates.

6. The coated gasket according to claim 2 or 3, characterized in that: The first baffle includes a first vertical portion connected to one end of the gasket body, and a first horizontal portion connected to a side of the first vertical portion away from the gasket body; The second baffle includes a second vertical portion connected to one end of the gasket body and a second transverse portion connected to a side of the second vertical portion away from the gasket body, wherein the chamfered areas are respectively arranged at ends of the first transverse portion and the second transverse portion.

7. The coated gasket according to claim 1, characterized in that: The gasket body, the first baffle plate and the second baffle plate are an integrated plate.

8. The coated gasket according to claim 1, characterized in that: The gasket body, the first baffle plate and the second baffle plate together form a C-shaped plate.

9. A coating device, characterized in that: include: A coated gasket as claimed in any one of claims 1 to 8.

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