Transfer type coating mechanism and transfer type coating equipment

Abstract

The invention discloses a transfer type coating mechanism and transfer type coating equipment, the transfer type coating mechanism comprises a coating roller, one side of the coating roller is provided with a slurry tank, in the autorotation process of the coating roller, the surface of the coating roller is coated with slurry in the slurry tank, and a coating area is formed on the surface of the coating roller; the backing roller and the base material abut against each other, the backing roller can convey the base material in the autorotation process, in the conveying process of the base material, the coating in the coating area is transferred to the surface of the base material, and a slurry layer is formed on the surface of the base material; the comma knife is arranged on one side of the coating roller, a knife face is arranged on the side, close to the coating roller, of the comma knife, a gap is reserved between the knife face and the coating roller, and protruding parts protruding towards the direction of the coating roller are arranged at the two ends of the knife face. And through the arrangement of the convex parts, a series of technical problems caused by peak formation during coating are solved.

Description

Technical Field

[0001] The invention relates to the coating field, in particular to a transfer coating mechanism and a transfer coating device. Background Art

[0002] In the existing transfer coating, an interface is formed on the coating roller at the coating edge, and then after being transferred to the foil, the slurry forms another interface on the foil. Due to the surface tension of the foil, the slurry forms a peak on the paste surface, which cannot be as smooth as the paste surface at other locations (see attached Figure 4 ), the thickness at this position is higher than that at other positions. The main hidden dangers brought by this problem are: 1) Since there is a peak on both sides, the thickness at the peak is greater than the normal coating thickness. When rolling, the compaction density at this position is too high and the belt is easy to break; 2) In the lamination process, the cumulative effect of the thickness at this position will seriously affect the thickness and flatness of the battery.

[0003] At present, there is no good way to control the peaks caused by the edge effect of the slurry. The only way to alleviate this problem is to reduce the viscosity of the slurry and increase the leveling of the slurry. How to solve a series of technical problems caused by the peaks caused by the edge effect of the slurry is still a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to overcome the above disadvantages, the object of the present invention is to provide a transfer coating mechanism that can solve a series of technical problems caused by the peaks generated by the edge effect of the slurry.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: a transfer coating mechanism, comprising: A coating roller, wherein a slurry tank is provided on one side of the coating roller, and during the self-rotation of the coating roller, the slurry in the slurry tank is coated on the surface of the coating roller to form a coating area on the surface of the coating roller; A backing roller, the substrate abuts against the backing roller, the backing roller can convey the substrate during its rotation, and during the conveying of the substrate, the coating in the coating area is transferred to the surface of the substrate to form a slurry layer on the surface of the substrate; A comma knife is arranged on one side of a coating roller, a knife surface is arranged on the side close to the coating roller, a gap is left between the knife surface and the coating roller, and protrusions protruding toward the coating roller are arranged at both ends of the knife surface.

[0006] By setting the raised part, a slurry layer that is thick in the middle and thin at both ends is formed on the surface of the substrate. Since the thickness at both ends of the slurry layer is thinner than the normal coating thickness, even if peaks are formed at both ends due to the edge effect, the height of the peaks will be lower than the normal coating thickness in the middle of the slurry layer. Since the thickness of the peaks will not be greater than the normal coating thickness at this time, it will not cause the compaction density at this position to be too high during rolling, which will easily cause the belt to break; and in the lamination process, this position will not be too thick, which will not affect the thickness and flatness of the battery. Therefore, the present application solves a series of technical problems caused by the formation of peaks during coating by improving the structure of the comma knife.

[0007] Furthermore, the thickness of the protrusion at the end of the comma blade is greater than the thickness of the protrusion near the middle of the comma blade, so that the formed slurry layer is thick in the middle section and gradually becomes thinner towards the two ends, thereby effectively controlling the distribution of the slurry on the substrate and ensuring the uniformity and consistency of the coating.

[0008] Furthermore, the main projection of the raised portion is a triangle, and the raised portion includes an inclined surface, and the inclined surface and the blade surface form an angle, and the angle is greater than 0°.

[0009] Furthermore, the angle range is 0<a≤5°. By controlling the angle between 0 and 5°, the length of the protrusion is longer, which can cover the area where the edge effect is generated, and no peaks will be generated in the area between the two protrusions at both ends of the comma knife.

[0010] Furthermore, the main projection of the raised portion is a rectangle, and the height T of the raised portion protruding toward the coating roller is 0<T≤50μm. Through the setting of the rectangular raised portion, after transfer coating, the paste surface at the edge of the pole piece has a gradient thinning. Although the edge of the pole piece will also produce a peak due to the edge effect, the thickness of this peak is less than the thickness of the normal position of the pole piece, and the overall thickness of the edge becomes thinner, and the thickness is less than 5~20μm of the thickness of the normal paste surface position. Such a pole piece will not have the problem of pole piece overpressure in the subsequent rolling process, the pole piece extension is basically the same, and the winding is good; it effectively solves the problem of peak thickness at the edge of the pole piece and the problems of overpressure, pole piece deformation, wrinkling, and poor winding in the subsequent rolling process.

[0011] Furthermore, the height T of the protrusion toward the coating roller is 20<T≤50 μm, so as to ensure that even if a peak of 5-20 μm is formed at the edge of the substrate 5, the height of the peak is lower than the thickness of the slurry layer.

[0012] Furthermore, the front projection of the raised portion is a right-angled trapezoid, and the thickness of the raised portion at the end of the comma knife is greater than the thickness of the raised portion near the middle of the comma knife.

[0013] Furthermore, the main projection of the raised portion is stepped, the number of steps n≥2, and the thickness of the raised portion at the end of the comma knife is greater than the thickness of the raised portion near the middle of the comma knife.

[0014] Furthermore, the protrusion is integrally connected to the blade surface, which improves the firmness of the connection between the protrusion and the comma knife, avoids the need to provide a connecting component between the protrusion and the blade surface, and makes the structure of the comma knife simpler.

[0015] Furthermore, the comma knife is connected to a driving mechanism, and the driving mechanism can drive the comma knife to move closer to or away from the coating roller, thereby controlling the coating thickness.

[0016] A transfer coating device comprises the transfer coating mechanism as described above.

[0017] The beneficial effects of the present invention are: 1) By setting the raised part, a slurry layer that is thick in the middle and thin at both ends is formed on the surface of the substrate. Since the thickness at both ends of the slurry layer is thinner than the normal coating thickness, even if peaks are formed at both ends due to the edge effect, the height of the peaks will be lower than the normal coating thickness in the middle of the slurry layer. Since the thickness of the peaks will not be greater than the normal coating thickness at this time, it will not cause the compaction density at this position to be too high during rolling, which will easily cause the belt to break; and in the lamination process, this position will not be too thick, which will not affect the thickness and flatness of the battery. Therefore, this application solves a series of technical problems caused by the formation of peaks during coating by improving the structure of the comma knife.

[0018] 2) By controlling the angle between 0 and 5 degrees, the length of the protrusion is longer and can cover the area where the edge effect occurs, and no peaks will be generated in the area between the two protrusions at both ends of the comma knife.

[0019] 3) Through the setting of the rectangular raised part, after transfer coating, the paste surface at the edge of the electrode has a gradient thinning. Although the edge of the electrode will also produce a peak due to the edge effect, the thickness of this peak is less than the thickness of the normal position of the electrode. The overall thickness of the edge becomes thinner, and the thickness is 5~20μm less than the thickness of the normal paste surface position. Such a pole piece will not have the problem of pole piece overpressure in the subsequent rolling process, the pole piece extension is basically the same, and the winding is good; it effectively solves the problem of peak thickness at the edge of the pole piece and the problems of overpressure, pole piece deformation, wrinkling, and poor winding in the subsequent rolling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 is a schematic diagram of a transfer coating mechanism according to an embodiment of the present invention; Figure 2 A schematic diagram of a comma knife in the prior art according to an embodiment of the present invention; Figure 3 A schematic diagram of a slurry layer in an ideal state according to an embodiment of the present invention; Figure 4 A schematic diagram of a slurry layer in a real state according to an embodiment of the present invention; Figure 5 A schematic diagram of a triangular protrusion according to an embodiment of the present invention; Figure 6 for Figure 5 A partial enlarged view of Figure 7 A schematic diagram of a slurry layer prepared using a comma knife provided with triangular protrusions; Figure 8 A schematic diagram of a rectangular protrusion according to an embodiment of the present invention; Fig. 9 for Figure 8 A partial enlarged view of Fig.10 is a schematic diagram of a slurry layer prepared using a comma knife provided with rectangular protrusions; Fig.11 A schematic diagram of a stepped protrusion according to an embodiment of the present invention; Fig.12 FIG. 4 is a schematic diagram of a right-angled trapezoidal protrusion according to an embodiment of the present invention.

[0023] In the figure: 1, comma knife; 11, knife surface; 2, coating roller; 3, slurry groove; 4, coating area; 5, substrate; 6, slurry layer; 61, peak; 7, back roller; 8, raised part; 81, inclined surface; 82, angle; 9, gap. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0025] In addition, the term "and / or" in this article 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 article, unless otherwise specified, generally means that the associated objects before and after are in an "or" relationship.

[0026] See attached Figure 1 As shown, the transfer coating mechanism in this embodiment includes a back roller 7, a substrate 5 and the back roller 7 are in contact, the back roller 7 is connected to a driving mechanism, the driving mechanism can drive the back roller 7 to rotate, and the substrate 5 is transported during the rotation of the back roller 7. The coating device also includes a coating roller 2, which is arranged on the left side of the back roller 7, and a slurry tank 3 is arranged on the left side of the coating roller 2. The coating roller 2 is fixed in position, the coating roller 2 is connected to the driving mechanism, and the coating roller 2 can rotate under the drive of the driving mechanism. During the rotation of the coating roller 2, the slurry in the slurry tank 3 is coated on the surface of the coating roller 2, and a coating area 4 is formed on the surface of the coating roller 2. During the clockwise rotation of the coating roller 2, the slurry in the coating area 4 is transferred to the substrate 5, and a slurry layer 61 is formed on the surface of the substrate 5.

[0027] A comma knife 1 is arranged above the coating roller 2. The comma knife 1 is connected to a driving mechanism. The driving mechanism can drive the comma knife 1 to approach or move away from the coating roller 2. The comma knife 1 can evenly distribute the slurry in the coating area 4 and then transfer and coat it on the substrate 5. The comma knife 1 is arranged to ensure that the slurry in the coating area 4 is evenly distributed, thereby ensuring that the slurry layer 6 on the substrate 5 is evenly distributed.

[0028] In the prior art, see Attachment Figure 2 As shown, the blade surface 11 of the conventional comma blade 1 is a straight line and is kept parallel to the surface of the coating roller 2 to ensure that the slurry is evenly coated on the substrate 5. In an ideal state, see the attached Figure 3 As shown in FIG. 5 , the slurry is evenly coated on the substrate 5 to form a flat slurry layer 6. However, due to the edge effect of the coating, such as the attached Figure 4 As shown, peaks 61 are formed on both sides of the slurry layer 6 formed by the coating evenly coated on the substrate 5. Since the thickness of the peak 61 is greater than the normal coating thickness, the compaction density at this position is too high during rolling, which is easy to break the belt; and in the lamination process, since this position is thicker, the cumulative effect will seriously affect the thickness and flatness of the battery; and the uneven thickness at this position will cause lithium precipitation, which poses a safety risk. The present application solves a series of technical problems caused by the formation of the peak 61 during coating by improving the structure of the comma knife 1.

[0029] See attached Figure 5 and attached Figure 6As shown, the middle part of the blade surface 11 of the comma knife 1 of the present application is a straight line, and protrusions 8 are arranged at both ends of the blade surface 11 of the comma knife 1. The protrusions 8 are arranged to protrude in the direction close to the coating roller 2. Through the arrangement of the protrusions 8, a gap 9 with a wide middle and narrow ends is formed between the comma knife 1 and the coating roller 2. The width of the gap is the thickness of the slurry in the coating area 4. Therefore, a coating with a thick middle and thin ends is formed on the surface of the coating roller 2. When the coating is transferred to the substrate 5, see the attached Figure 7 As shown, a slurry layer 6 with a thick middle and thin ends is also formed on the surface of the substrate 5. The middle thickness here refers to the coating at both ends of the substrate 5. The thickness of the slurry layer 6 in the middle of the substrate 5 is the general thickness of the slurry layer 6 in the traditional coating process, and the thin ends only means that the thickness of the two ends of the slurry layer 6 is thinner than the thickness of the middle coating.

[0030] Since the thickness at both ends of the slurry layer 6 is thinner than the normal coating thickness, even if peaks 61 are formed at both ends due to the edge effect, the height of the peaks 61 will be lower than the normal coating thickness in the middle of the slurry layer 6. Since the thickness at the peaks 61 will not be greater than the normal coating thickness at this time, it will not cause the compaction density at this position to be too high during rolling, which will easily cause the tape to break; and in the lamination process, this position will not be too thick, which will not affect the thickness and flatness of the battery. Therefore, the present application solves a series of technical problems caused by the formation of peaks 61 during coating by improving the structure of the comma knife 1.

[0031] In some embodiments, the raised portion 8 and the blade surface 11 are integrally connected, which improves the firmness of the connection between the raised portion and the comma knife and avoids the need to set a connecting component between the raised portion 8 and the blade surface 11, making the structure of the comma knife 1 simpler.

[0032] In some embodiments, the raised portion 8 is formed by bending the blade surfaces 11 at both ends toward the coating roller 2. The main projection of the raised portion 8 is a triangle. The raised portion 8 includes an inclined surface 81. A gap 9 is left between the inclined surface 81 and the coating roller 2 to ensure that the slurry layer 6 can be formed on the substrate 5. The inclined surface 81 and the blade surface 11 of the comma knife 1 form an angle 82, and the range of the angle 82 is 0<a≤5°, that is, the two ends of the comma knife 1 are inclined toward the coating roller 2 by 0~5° respectively.

[0033] If the angle 82 is too large, in order to ensure that there is a gap between the protrusion 8 and the coating roller 2, the length of the protrusion must be short, and it cannot completely cover the area where the edge effect occurs. A peak may be generated again in the area between the two protrusions, and the problem of the peak 61 cannot be solved well. Through verification, when the angle is controlled between 0 and 5 degrees, the length of the protrusion 8 is longer, which can cover the area where the edge effect occurs, and the area between the two protrusions 8 at both ends of the comma knife 1 will not generate a peak 61. The length of the protrusion only refers to the length along the direction in which the blade surface 11 extends.

[0034] After the conventional comma knife 1 completes the transfer coating, due to the surface tension of the foil, the slurry will form an edge effect at the junction of the foil and the paste surface, resulting in a paste surface peak 61 in the slurry layer 6. The thickness of this position is generally about 5 to 20 microns (single side) higher than the thickness of the normal position. In the subsequent electrode rolling process, due to the thick thickness of this position, the electrode at this position will be over-pressed, and the extension of the foil will be greater than that of other positions, resulting in uneven extension of the entire electrode, causing the electrode to wrinkle, unable to be rolled normally, or even broken pieces and other serious defects; See attached Figure 7 As shown, due to the setting of the inclined surface 81 of the comma knife 1 of the present invention, after transfer coating, the paste surface at the edge of the electrode has a gradual thinning, so that there will be no peak 61 paste surface at the edge of the slurry layer 6. At the same time, the edge will be appropriately thinned, and the thickness is about 5~20μm less than the thickness of the normal paste surface position. Such a pole piece will not have the problem of pole piece overpressure in the subsequent rolling process, the pole piece extension is basically the same, and the winding is good; it effectively solves the problem of the thickness of the peak 61 at the edge of the pole piece and the problems of overpressure, pole piece deformation, wrinkling, and poor winding in the subsequent rolling process.

[0035] In some other embodiments, see the attached Figure 8-10 As shown, the main projection of the raised portion 8 is a rectangle, and the height T protruding toward the coating roller 2 is 0<T≤50μm. Through the setting of the rectangular raised portion 8, after transfer coating, the paste surface at the edge of the pole piece has a gradient thinning. Although the edge of the pole piece will also produce a spike 61 due to the edge effect, the thickness of this spike 61 is less than the thickness of the normal position of the pole piece, and the overall thickness of the edge becomes thinner, and the thickness is 5~20μm less than the thickness of the normal paste surface position. Such a pole piece will not have the problem of pole piece overpressure in the subsequent rolling process, the pole piece extension is basically the same, and the winding is good; it effectively solves the problem of the thickness of the spike 61 at the edge of the pole piece and the problems of overpressure, pole piece deformation, wrinkling, and poor winding in the subsequent rolling process.

[0036] Preferably, the height T of the protrusion 8 protruding toward the coating roller 2 is 20<T≤50 μm, so as to ensure that even if a peak 61 of 5-20 μm is formed at the edge of the substrate 5 , the height of the peak 61 is lower than the thickness of the slurry layer 6 .

[0037] In some embodiments, see Appendix Fig.11 As shown, the front projection of the protrusion 8 is a right-angled trapezoid, and the hypotenuse of the trapezoid makes the slurry layer 61 gradually thinner. Fig.12 As shown, the main projection of the raised portion 8 may also be stepped, and the number of steps n≥2. The specific number of steps depends on actual needs and is not limited in this application.

[0038] By setting the raised portion 8, during the coating process on the substrate 5, the thickness of the film layer at the edge of the slurry layer 6 is reduced, and the problem of the peak 61 due to the edge effect is solved. The specific shape of the raised portion 8 can achieve the technical effect, such as a triangle, a rectangle, a right-angled trapezoid, or a step shape in the main view projection, which will not be listed one by one in this application.

[0039] By providing raised portions 8 on the blade surface 11 at both ends of the comma knife 1, after the transfer coating is completed, the edge of the electrode sheet will become gradually or gradient thinner, which is very beneficial to the subsequent turnover and processing of the electrode sheet after the transfer coating. Compared with conventional processes, this patent is particularly important for controlling the edge thickness of the transfer coating of lithium-ion batteries.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A transfer coating mechanism, characterized in that: include: A coating roller (2), wherein a slurry tank (3) is provided on one side of the coating roller (2), and when the coating roller (2) rotates, the slurry in the slurry tank (3) is coated on the surface of the coating roller (2), forming a coating area (4) on the surface of the coating roller (2); A back roller (7), which can transport the substrate (5) during its rotation, wherein the coating in the coating area (4) is transferred to the surface of the substrate (5) during the transport of the substrate (5), forming a slurry layer (6) on the surface of the substrate (5); A comma knife (1), the comma knife (1) being arranged on one side of a coating roller (2), the comma knife (1) being provided with a knife surface (11) on the side close to the coating roller (2), a gap being left between the knife surface (11) and the coating roller (2), and protrusions (8) protruding towards the coating roller (2) being provided at both ends of the knife surface (11).

2. The transfer coating mechanism according to claim 1, characterized in that: The thickness of the raised portion (8) at the end of the comma knife (1) is greater than the thickness of the raised portion (8) near the middle of the comma knife (1).

3. The transfer coating mechanism according to claim 2, characterized in that: The main projection of the raised portion (8) is a triangle, the raised portion (8) comprises an inclined surface (81), the inclined surface (81) and the blade surface (11) form an angle (82), and the angle (82) is greater than 0°.

4. The transfer coating mechanism according to claim 3, characterized in that: The range of the included angle (82) is 0<a≤5°.

5. The transfer coating mechanism according to claim 1, characterized in that: The front projection of the protrusion (8) is a rectangle, and the height T of the protrusion (8) protruding in the direction of the coating roller (2) is 0<T≤50μm.

6. The transfer coating mechanism according to claim 1, characterized in that: The height T of the protruding portion (8) protruding in the direction of the coating roller (2) is 20<T≤50μm.

7. The transfer coating mechanism according to claim 2, characterized in that: The front projection of the protrusion (8) is in the shape of a right-angled trapezoid or a step, and the number of steps n is ≥2.

8. The transfer coating mechanism according to claim 1, characterized in that: The raised portion (8) and the blade surface (11) are integrally connected.

9. The transfer coating mechanism according to claim 1, characterized in that: The comma knife (1) is connected to a driving mechanism, and the driving mechanism can drive the comma knife (1) to move toward or away from the coating roller (2).

10. A transfer coating device, comprising the transfer coating mechanism according to any one of claims 1 to 9.

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