Battery slurry coating device

Abstract

The utility model discloses a battery slurry coating device which comprises a coating head, a material supply pipe and a material storage tank, the coating head is provided with a material uniformizing cavity and a material uniformizing gap communicated with the material uniformizing cavity, and the material uniformizing cavity of the coating head is communicated with the material storage tank through the material supply pipe; a coating cavity communicated with the material uniformizing gap is formed in the front end of the coating head, the coating cavity is provided with a coating area enabling battery slurry to be in contact with the base material, and an adjusting plate is fixedly arranged at an outlet of the coating cavity; and the difference value of the vertical distance from each point in the wall surface, closest to the base material, of the adjusting plate to the base material is 0-3mm. According to the utility model, the coating mode is changed, the slurry is firstly contacted with the base material in the coating cavity and then passes through the gap between the adjusting plate and the base material, and the width of the gap in the movement direction of the base material is greater than 3mm, so that the uniform flowing of the slurry can be completed, and the slurry is coated to the target thickness. Therefore, the influence of non-uniform transverse flow at the slurry outlet on the uniformity of the slurry coating on the surface of the base material is weakened, and the coating quality can be effectively improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion battery production, and relates to the coating of battery pole pieces, in particular to a battery slurry coating device. Background Art

[0002] The coating process is an important step in the production of lithium-ion batteries. Its purpose is to make the positive and negative electrode materials of lithium-ion batteries into slurry and evenly coat them on the current collector, and then dry them to form battery pole pieces. The quality of coating directly affects the performance of the battery.

[0003] At present, the extrusion coating head is widely used in the coating process. Its structure mainly includes three parts: upper die, lower die and gasket. The lower die is provided with a material balancing cavity, the upper die is provided with a material balancing valve, and a material balancing gap is formed between the upper die and the lower die. During the coating operation, the slurry is spread horizontally in the material balancing cavity, and then flows to the coating port through the material balancing gap, and directly adheres to the current collector (hereinafter referred to as: substrate) at the coating port to form a flat and smooth surface. At the material balancing gap, the slurry flow rate can be adjusted by the material balancing valve to ensure uniform and stable coating.

[0004] With the development of lithium-ion batteries, the coating process has higher requirements for coating uniformity. Lithium-ion battery slurry is a non-Newtonian fluid with the characteristics of shear thinning and sedimentation when not sheared. When using the above-mentioned traditional extrusion coating head, due to its structural limitations, slurry accumulation will occur at the entrance of the equalizing chamber, and the entrance pressure will be greater than other lateral positions, which will make the lateral flow of the slurry at the coating port uneven, resulting in poor uniformity of the coating thickness on the substrate surface. Utility Model Content

[0005] In order to solve the above deficiencies in the prior art, the utility model aims to provide a battery slurry coating device to achieve the purpose of improving the uniformity of the slurry coating on the surface of the substrate.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the utility model is as follows: a coating device for battery slurry, comprising a coating head, a feeding pipe and a material storage tank, the coating head having a material-leveling cavity and a material-leveling gap connected to the material-leveling cavity, the feeding pipe connecting the material-leveling cavity of the coating head with the material storage tank; a coating cavity connected to the material-leveling gap is provided at the front end of the coating head, the coating cavity having a coating area for contacting the battery slurry with the substrate, the outlet of the coating cavity being arranged at the rear side of the coating area, and an adjusting plate being fixed at the outlet;

[0007] The difference in vertical distances between each point on the wall closest to the substrate and the adjusting plate is 0 to 3 mm; along the moving direction of the substrate, the width of the gap between the adjusting plate and the substrate is greater than 3 mm.

[0008] As a limitation of the present invention, both sides of the coating head are provided with a reflux pipe connected to the material equalization chamber, and the other end of the reflux pipe is connected to the material storage tank;

[0009] A circulation pump is provided on the reflux pipe or the feed pipe.

[0010] As a further limitation of the present invention, a pressure sensor is arranged in the coating chamber of the coating head.

[0011] As another limitation of the present invention, first coating plates are fixedly provided on both sides of the coating head, and a first sealing member is provided between the first coating plate and the substrate.

[0012] As a further limitation of the present invention, at least one second coating plate is mounted on the coating head, and a second sealing member is disposed between the second coating plate and the substrate.

[0013] As a further limitation of the present invention, at least one third coating plate is fixedly disposed in the coating chamber, and a third sealing member is disposed between the third coating plate and the substrate.

[0014] As another limitation of the present invention, the coating head comprises an upper die and a lower die that match each other; the upper die is provided with a material balancing valve, the lower die is provided with the material balancing cavity, and the material balancing gap is formed between the upper die and the lower die;

[0015] The working end of the material equalizing valve is located at the material equalizing gap.

[0016] Due to the adoption of the above technical solution, the utility model has the following beneficial effects compared with the prior art:

[0017] (1) The utility model changes the coating method. By setting a coating chamber and an adjustment plate at the front end of the coating head, the slurry first contacts the substrate, and then passes through the gap between the adjustment plate and the substrate. The width of the gap in the direction of substrate movement is greater than 3mm, which can complete the uniform flow of the slurry and coat it to the target thickness. It is equivalent to a secondary coating, which weakens the effect of uneven lateral flow at the slurry outlet on the uniformity of the slurry coating on the substrate surface, and can effectively improve the coating quality. The utility model can make the slurry coating smoother, more uniform, and free of bubbles.

[0018] (2) The utility model is provided with reflux pipes on both sides of the coating head, which are connected to the storage tank, and a circulation pump is provided to circulate the slurry in the material mixing chamber and the storage tank, so as to keep the slurry in a flowing state at all times and prevent sedimentation. This internal circulation method utilizes the shear-thinning fluid property of lithium-ion battery slurry, effectively reduces the viscosity of the slurry, makes it more fluid, and thus solves the problem of poor coating uniformity caused by high viscosity and the inability of the slurry to self-level in the material mixing chamber.

[0019] (3) A pressure sensor is provided in the coating chamber of the utility model, which can detect the slurry pressure in the coating chamber in real time; a material equalizing valve is provided at the material equalizing gap, and the amount of slurry entering the coating chamber in the horizontal direction can be adjusted by opening and closing the valve. Combined with the feedback of the pressure sensor, uniform material supply to the coating chamber in the horizontal direction is achieved.

[0020] (4) In the present invention, the first coating plate is provided on both sides of the coating head to limit the coating width; the second coating plate mounted on the coating head and the third coating plate fixed in the coating chamber can both achieve multiple coatings in the horizontal direction. In addition, the seal provided between the coating plate and the substrate can prevent the slurry from overflowing into the uncoated area. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Figure 1 A side view of the structure of an embodiment of the utility model;

[0023] Figure 2 A top view of the structural relationship of a single longitudinal coating in an embodiment of the utility model;

[0024] Figure 3 A top view of the structural relationship of the longitudinal double-strip coating of this practical embodiment;

[0025] In the figure: 1. substrate; 2. power roller; 3. upper mold; 4. lower mold; 5. material equalization chamber; 6. material equalization valve; 7. coating chamber; 8. adjustment plate; 9. pressure sensor; 10. feed pipe; 11. reflux pipe; 12. side hole; 13. slurry inlet; 14. circulation pump; 15. first coating plate; 16. third coating plate, 17. storage tank. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and understand the present invention, and are not used to limit the present invention.

[0027] like Figure 1 As shown, this embodiment includes a coating head, a feed pipe 10, a return pipe 11 and a storage tank 17. The feed pipe 10 and the return pipe 11 connect the coating head with the storage tank 17, and a circulation pump 14 is provided to circulate the slurry in the material mixing chamber 5 and the storage tank 17, thereby keeping the slurry in a flowing state at all times during the coating process to prevent sedimentation.

[0028] Specifically, the coating head includes an upper mold 3, a lower mold 4 and a gasket, wherein the upper mold 3 and the lower mold 4 are matched, and the gasket is located between the upper mold 3 and the lower mold 4. Depending on the actual situation, the gasket may not be provided. The upper mold 3 is provided with a material equalizing valve 6, and the lower mold 4 is provided with a material equalizing cavity 5 and a slurry inlet 13 connected to the material equalizing cavity 5. After the upper mold 3 and the lower mold 4 are matched, a material equalizing gap is formed between the two, and the material equalizing gap is connected to the material equalizing cavity 5 for the slurry to pass through.

[0029] Furthermore, a coating chamber 7 is provided at the front end of the coating head, the coating chamber 7 is connected to the material sizing chamber 5 through the material sizing gap, and the coating chamber 7 has a coating area for the slurry to contact the substrate 1, and a pressure sensor 9 is arranged in the coating chamber 7. Figure 1 As shown, one side of the coating chamber 7 is connected to the material-splitting gap, and the other side is an open side. The shape of the open side is adapted to the shape of the substrate 1 to be coated on the power roller 2. The substrate 1 to be coated can just close the open side of the coating chamber 7, so that only an outlet is reserved at the top. The outlet is located at the rear side of the coating area, and an adjustment plate 8 is fixed. It should be noted here that "the outlet is located at the rear side of the coating area" means that along the movement direction of the substrate 1, the substrate 1 first passes through the coating area and then passes through the adjustment plate 8. Figure 1 The direction of the middle arrow is the moving direction of the substrate 1 .

[0030] The adjustment plate 8 is an arc-shaped plate, the length of which is consistent with the length of the coating head, and the arc is the same or similar to the curvature of the substrate 1 on the power roller 2. It is fixed on the upper mold 3 of the coating head and is parallel to the surface of the substrate 1. In the wall surface of the adjustment plate 8 closest to the substrate 1, the vertical distances from each point to the substrate 1 are equal or similar (the difference in the vertical distances from each point to the substrate 1 is 0 to 3 mm). Adjusting this distance can adjust the coating thickness. In this embodiment, the arc length of the wall surface of the adjustment plate 8 closest to the substrate 1 is greater than 3 mm, so that in the direction of movement of the substrate 1, the gap width between the adjustment plate 8 and the substrate 1 is greater than 3 mm, which can better complete the uniform flow of the slurry.

[0031] During coating, the slurry enters the coating chamber 7 from the material-distributing chamber 5 through the material-distributing gap, adheres to the surface of the substrate 1 in the coating chamber 7, and moves toward the outlet of the coating chamber 7 along with the substrate 1. The slurry is intercepted by the regulating plate 8 at the outlet to form a coating of a specified thickness.

[0032] More specifically, the slurry inlet 13 on the coating head is opened at the middle position of the side of the lower mold 4. In this embodiment, side holes 12 are opened at the middle positions of both end surfaces of the coating lower mold 4. The slurry inlet 13 and the side holes 12 are both connected to the material equalization cavity 5 of the coating head.

[0033] The storage tank 17, the feed pipe 10 and the return pipe 11 are all existing structures. Among them, one end of the feed pipe 10 is connected to the outlet of the storage tank 17, and the other end is connected to the slurry inlet 13 of the coating head; the return pipe 11 includes two return branch pipes and a return main pipe, the return branch pipes are connected to the side holes 12 of the coating head, and are connected to the return main pipe, and the return main pipe is connected to the inlet of the storage tank 17.

[0034] In this embodiment, the circulation pump 14 is arranged on the feed pipe 10. Of course, the circulation pump 14 can also be arranged on the reflux main pipe according to the actual situation.

[0035] The equalizing valve 6 is arranged on the upper die 3 of the coating head, and its working end is located at the equalizing gap, and the slurry flow rate passing through the equalizing gap is adjusted by intercepting the flow. In this embodiment, the equalizing valve 6 is an existing micrometer equalizing adjustment mechanism, and the specific structure is not repeated.

[0036] like Figure 2 As shown, in this embodiment, a first coating plate 15 is fixedly provided on both sides of the coating head for setting the coating width, and a first seal is provided between the coating plate and the substrate 1. According to actual needs, a coating plate can also be installed on the coating head to achieve multiple coatings. For example: a second coating plate is sleeved on the coating head, and at least one second coating plate needs to be provided, the coating head as a whole is segmented, and a second seal is provided at the contact position between the second coating plate and the substrate 1. For another example: a third coating plate 16 is fixedly provided in the coating cavity 7 of the coating head, and at least one third coating plate 16 needs to be provided, such as Figure 3 As shown, only the coating chamber 7 is segmented, and a third sealing member is provided at the contact position between the third coating plate 16 and the substrate 1 .

[0037] The working process of this embodiment is as follows:

[0038] Fill the coating chamber 7 with the slurry, so that the slurry is in full contact with the coating area of ​​the substrate 1 on the power roller 2 in the coating chamber 7, so that the slurry adheres to the surface of the substrate 1, and the adhesion thickness of the slurry is greater than the target thickness to be coated;

[0039] The power roller 2 drives the substrate 1 to move forward, so that the substrate 1 and the slurry adhered to the surface pass through the adjustment plate 8, and the excess slurry is blocked and remains in the coating cavity 7. The slurry passing through the adjustment plate 8 forms a uniform slurry coating on the surface of the substrate 1.

[0040] It should be noted that the above is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A coating device for battery slurry, comprising a coating head, a feeding pipe and a storage tank, wherein the coating head has a material-leveling cavity and a material-leveling gap connected to the material-leveling cavity, and the feeding pipe connects the material-leveling cavity of the coating head with the storage tank; characterized in that: The front end of the coating head is provided with a coating chamber connected with the material-splitting gap, the coating chamber has a coating area for contacting the battery slurry with the substrate, the outlet of the coating chamber is arranged at the rear side of the coating area, and an adjusting plate is fixed at the outlet; The difference in vertical distances between each point on the wall closest to the substrate and the adjusting plate is 0 to 3 mm; along the moving direction of the substrate, the width of the gap between the adjusting plate and the substrate is greater than 3 mm.

2. A battery slurry coating device according to claim 1, characterized in that: Both sides of the coating head are provided with a reflux pipe connected to the material distribution chamber, and the other end of the reflux pipe is connected to the material storage tank; A circulation pump is provided on the reflux pipe or the feed pipe.

3. A battery slurry coating device according to claim 2, characterized in that: A pressure sensor is arranged in the coating chamber of the coating head.

4. A battery slurry coating device according to any one of claims 1 to 3, characterized in that: A first coating plate is fixedly arranged on both sides of the coating head, and a first sealing member is arranged between the first coating plate and the substrate.

5. A battery slurry coating device according to claim 4, characterized in that: At least one second coating plate is mounted on the coating head, and a second sealing member is disposed between the second coating plate and the substrate.

6. A battery slurry coating device according to claim 4, characterized in that: At least one third coating plate is fixedly arranged in the coating chamber, and a third sealing member is arranged between the third coating plate and the substrate.

7. A battery slurry coating device according to any one of claims 1-3, 5-6, characterized in that: The coating head comprises an upper die and a lower die that match each other; the upper die is provided with a material balancing valve, the lower die is provided with the material balancing cavity, and the material balancing gap is formed between the upper die and the lower die; The working end of the material equalizing valve is located at the material equalizing gap.

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