Secondary battery high viscosity slurry coating method and apparatus

Abstract

The application discloses a secondary battery high-viscosity slurry coating method and device. The coating method is as follows: after the coating substrate sequentially passes through a slurry gap in a vacuum environment and a discharge gap for controlling the thickness of the coating slurry, the coating substrate is coated, and a uniform pole piece is obtained. The discharge gap is arranged on the basis of the slurry cavity. The coating device comprises a coating back roller, a coating member is arranged on the coating back roller, the coating member and the outer periphery of the coating back roller form a gap for coating the coating substrate, the coating member comprises a vacuum cavity and a slurry cavity which are communicated with the slurry gap for first coating the coating substrate, and a coating substrate leading-in mechanism is arranged at the end of the vacuum cavity away from the slurry cavity; a slurry inlet is arranged on the slurry cavity, and a casing at the end of the slurry cavity away from the vacuum cavity and the coating back roller form a discharge gap for re-coating. The device has the advantages of simple structure, convenient operation and the ability to effectively and uniformly coat high-viscosity slurry.

Description

Technical Field

[0001] This invention belongs to the technical field of secondary battery production, and relates to a slurry coating method in secondary battery production, specifically a method for coating high-viscosity slurry for secondary batteries. This invention also relates to a high-viscosity slurry coating apparatus for secondary batteries. Background Technology

[0002] In the production of rechargeable batteries, the coating process is a crucial step, and its quality directly affects the performance of the final lithium-ion battery electrode. Current coating technologies typically employ extrusion or transfer processes to uniformly coat a slurry (comprising the rechargeable battery's positive and negative electrode materials, conductive agents, binders, and solvents) onto a current collector, forming a smooth, evenly coated, well-adhered, and bubble-free electrode. These methods place high demands on the slurry's adhesion, kinematic viscosity, and flowability. This is because using high-viscosity slurries presents two problems: first, the strong adhesion between the slurry and the substrate prevents self-leveling (the slurry cannot form a smooth surface under gravity and surface tension); second, during high-speed coating, poor slurry flowability prevents the slurry from quickly displacing gases from the substrate surface, allowing the substrate to carry these adsorbed gases into the slurry, resulting in defects such as pinholes, foil leaks, and bubbles on the rechargeable battery electrode surface.

[0003] To avoid coating defects in high-viscosity slurries, existing technologies typically involve adding a large amount of diluent to the slurry during the mixing process to reduce its viscosity. While this method can reduce the viscosity, it can still cause negative effects during the later coating process, such as slurry stratification, agglomeration of active materials and conductive agents, and increased internal resistance of secondary batteries. Furthermore, low-viscosity slurries have a high diluent content, requiring all the diluent to be baked out after coating, which consumes a lot of energy during drying, affecting production efficiency and wasting resources. Summary of the Invention

[0004] The purpose of this invention is to provide a method for coating high-viscosity slurry for secondary batteries that is simple to operate, has high production efficiency, and produces high-quality products.

[0005] Another objective of this invention is to provide a coating apparatus that utilizes vacuum low pressure and multi-pass coating to solve problems such as uneven surface of secondary battery electrode sheets, foil leakage, and air bubbles that occur when using high-viscosity slurry coating in the prior art, resulting in a more uniform, smooth, and even coating of high-viscosity slurry.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0007] A method for coating a high-viscosity slurry for a secondary battery, comprising: coating a substrate sequentially through a slurry gap in a vacuum environment and an outlet gap for controlling the thickness of the coating slurry, thereby obtaining a uniformly coated electrode sheet, wherein the outlet gap is provided based on the slurry cavity.

[0008] As a limitation of this method, after the coating substrate is coated through the slurry gap and before it is coated through the outlet gap, a guide plate gap is also provided to coat the coating substrate.

[0009] As a further limitation of this method, the gaps in the guide plate and the outlet can be adjusted in size under the drive of an external driving mechanism.

[0010] As a further limitation of this method, the gap of the guide plate is 0.2 to 15 mm and the gap of the discharge port is 0.01 to 5 mm.

[0011] As a further limitation of this method, after the coating substrate is coated through the guide plate gap or the outlet gap, a transverse blanking treatment step is set; during the coating process of the coating substrate from the slurry gap to the outlet gap, a longitudinal blanking treatment step is set simultaneously.

[0012] The present invention also provides a coating apparatus for using the above-described coating method, comprising a coating back roller, a coating component disposed on the coating back roller, the coating component having a cavity structure, the coating component and the outer periphery of the coating back roller forming a slit for coating the substrate, wherein the coating component includes a vacuum chamber and a slurry chamber connected by a slurry slit for the first coating of the substrate, the vacuum chamber being provided with a vacuum port for extracting gas, and a substrate inlet mechanism being provided at the end of the vacuum chamber away from the slurry chamber; the slurry chamber being provided with a slurry inlet for injecting slurry, and an outlet for re-coating and discharging the substrate being coated being formed between the shell of the slurry chamber away from the vacuum chamber and the coating back roller.

[0013] As a limitation of the above coating device: the slurry chamber is also provided with a guide plate that moves along the direction of the coating substrate under the drive of an external drive mechanism, and the guide plate and the outer periphery of the coating back roller form a guide plate gap for secondary coating of the coating substrate.

[0014] As another limitation of the above coating device: the slurry chamber 1 is provided with a slurry baffle parallel to the direction of movement of the coating substrate, the length of the slurry baffle extends from the slurry gap to the discharge port, and the slurry baffle moves away from or close to the coating back roller under the drive of the external drive mechanism.

[0015] As a third limitation on the above-mentioned coating apparatus, it further includes a discharge port sealing plate disposed along the width direction of the coating substrate, the discharge port sealing plate being located between the discharge port and the guide plate or behind the discharge port, and being driven away from or close to the coating back roller by an external drive mechanism.

[0016] As a fourth limitation on the above-described coating apparatus, the coating substrate introduction mechanism has one of the following structures:

[0017] It includes a vacuum-sealed constant-speed roller and a vacuum-sealed roller tangentially disposed on the vacuum chamber housing, with the substrate in the coating area passing between the vacuum-sealed constant-speed roller and the vacuum-sealed roller;

[0018] The vacuum chamber includes a vacuum-sealed constant-speed roller mounted on the vacuum chamber housing. The vacuum-sealed constant-speed roller is tangent to the coating back roller. A pressure roller tangent to the coating back roller is mounted inside the vacuum chamber. The coating substrate passes sequentially between the vacuum-sealed constant-speed roller and the coating back roller, and between the pressure roller and the coating back roller.

[0019] The vacuum-sealed constant-speed roller is mounted on the vacuum chamber housing. The vacuum-sealed constant-speed roller is tangent to the coating back roller. A passing roller and a pressure roller tangent to the coating back roller are arranged inside the vacuum chamber. The coating substrate passes sequentially between the vacuum-sealed constant-speed roller and the coating back roller, between the passing roller and the pressure roller and the coating back roller.

[0020] It includes a sealing member disposed on the vacuum chamber housing and pressed against the outer periphery of the coating back roller, through which the coating substrate passes.

[0021] As a fifth limitation on the above-mentioned coating apparatus: the vacuum port includes at least two spaced apart on the vacuum chamber along the direction of movement of the coating substrate; the guide mechanism includes a guide member disposed between two adjacent vacuum ports, the guide member is disposed on the vacuum chamber housing and presses against the outer periphery of the coating back roller, and the coating substrate passes between the guide member and the coating back roller.

[0022] As a further limitation on the above-mentioned high-viscosity slurry coating device for secondary batteries, the gap between the guide plate and the coating back roller is 0.2-15 mm, the gap between the discharge port and the coating back roller is 0.01-5 mm, the distance between the discharge port sealing plate and the discharge port is 0.1 mm-15 mm, and the distance between the guide plate and the discharge port is 0.01-15 mm.

[0023] As a further limitation on the above-mentioned high-viscosity slurry coating device for secondary batteries, the included angle between the discharge port and the coating back roller is 0° to 60°.

[0024] The present invention, by adopting the above-mentioned technical solution, achieves the following technical progress compared with the prior art: (1) When the method of the present invention applies slurry to the substrate, a vacuum environment slurry gap is first introduced so that the high-viscosity slurry can drive away the thin gas on the substrate surface when applying the slurry, effectively avoiding the problems of pinholes, foil leakage, and bubbles on the electrode surface caused by the substrate adsorbing a large amount of gas on its surface into the slurry during the coating process in the prior art. Furthermore, by sequentially setting slurry gaps and outlet gaps during the slurry coating process, the high-viscosity slurry can be coated smoothly and uniformly after multiple coating processes.

[0025] (2) The method of the present invention also sets a guide plate gap for two-pass coating during the coating process of the coating substrate, which, together with the slurry gap for one-pass coating and the discharge port gap for three-pass coating, makes the high viscosity slurry coated on the coating substrate smoother and more uniform.

[0026] (3) The coating device of the present invention adds a vacuum chamber structure to the slit coating of the prior art. The vacuum chamber structure is provided with a vacuum port for extracting gas. When in use, it is only necessary to continuously extract gas from the vacuum port to form a vacuum environment. The operation is simple and convenient.

[0027] (3) The device of the present invention has a driveable guide plate structure in the slurry chamber, and the lateral thickness of the slurry coating is adjusted by controlling the movement of the guide plate structure.

[0028] (4) The slurry chamber of the device of the present invention is provided with a slurry baffle parallel to the direction of movement of the coating substrate. The slurry baffle is controlled to approach the coating back roller by an external driving mechanism, and the slurry baffle is always pressed against the coating back roller during the coating process, thereby realizing the longitudinal blanking treatment of the coating substrate. The slurry chamber is also provided with an outlet sealing plate arranged along the width direction of the coating substrate between the outlet and the guide plate. The outlet sealing plate is controlled to move away from or close to the coating back roller by an external driving mechanism to realize the transverse blanking treatment of the substrate.

[0029] In summary, the high-viscosity slurry coating device for secondary batteries of the present invention has a simple structure and is easy to operate, which can improve production efficiency and reduce energy consumption. Furthermore, the method of the present invention can make the high-viscosity slurry coating smoother, more uniform, with better adhesion and no bubbles, thus improving the coating quality of secondary batteries in the coating process. When using the device of the present invention to coat high-viscosity slurries, it can effectively reduce the energy consumption of subsequent drying by 5%-20%. The method of the present invention is applicable to slurry coating on any coating substrate. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1This is a front view of Embodiment 1 of the present invention;

[0032] Figure 2 This is a top view of Embodiment 1 of the present invention;

[0033] Figure 3 This is a detailed view of each component in the slurry chamber 1 in Embodiment 1 of the present invention;

[0034] Figure 4 This is a schematic diagram of the second structure of the infeeding mechanism in Embodiment 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of the third structure of the infeeding mechanism in Embodiment 1 of the present invention;

[0036] Figure 6 This is a schematic diagram of the fourth structure of the infeeding mechanism in Embodiment 1 of the present invention;

[0037] Figure 7 This is a front view of Embodiment 2 of the present invention;

[0038] Figure 8 This is a detailed drawing of the components in the vacuum cavity 2 in Embodiment 2 of the present invention.

[0039] In the diagram: 1. Slurry chamber; 2. Vacuum chamber; 3. Coating back roller; 4. Passing roller; 5. Coating substrate; 6. Electrode; 11. Discharge port; 12. Discharge port sealing plate; 13. Slurry chamber shell; 14. Guide plate; 15. Slurry inlet; 16. Guide plate driver; 17. Slurry baffle; 18. Coating plate; 21. Vacuum port; 22. Vacuum chamber shell; 23. Vacuum sealing constant speed roller; 24. Vacuum sealing roller; 25. Pressure roller; 27. Sealing component; 61. Longitudinal blank area; 62. Transverse blank area. Detailed Implementation

[0040] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example 1: High-viscosity slurry coating device for secondary batteries

[0042] This embodiment provides a high-viscosity slurry coating device for secondary batteries, such as... Figure 1 , Figure 2 As shown, it includes a coating back roller 3, on which a coating component is disposed. In this embodiment, the coating component has a cavity structure, and the coating component and the outer periphery of the coating back roller 3 form a slit for coating the substrate. The coating component includes a vacuum chamber 2 and a slurry chamber 1 connected by a slurry gap. In this embodiment, the slurry gap can perform the first coating on the substrate 5.

[0043] In this embodiment, to achieve the vacuum effect of the vacuum chamber 2, a vacuum port 21 for extracting gas is provided on the vacuum chamber 2. To allow the coating substrate to enter the vacuum chamber 2, a coating substrate introduction mechanism is provided at the end of the vacuum chamber 2 away from the slurry chamber 1, such as... Figure 1 As shown, in this embodiment, the substrate introduction mechanism consists of tangent vacuum-sealed constant-speed rollers 23 and 24, and the substrate 5 in the coating area passes between the vacuum-sealed constant-speed rollers 23 and 24; or as shown... Figure 4 As shown, the substrate introduction mechanism can also be a vacuum-sealed constant-speed roller 23 mounted on the housing of the vacuum chamber 2. The vacuum-sealed constant-speed roller 23 is tangent to the coating back roller 3. A pressure roller 25, tangent to the coating back roller 3, is disposed inside the vacuum chamber 2. The coating substrate 5 passes sequentially between the vacuum-sealed constant-speed roller 23 and the coating back roller 3, and between the pressure roller 25 and the coating back roller 3; or as shown... Figure 5 As shown, the coating substrate introduction mechanism can also be a vacuum-sealed constant-speed roller 23 mounted on the housing of the vacuum chamber 2. The vacuum-sealed constant-speed roller 23 is tangent to the coating back roller 3. A guide roller 4 and a pressure roller 25 tangent to the coating back roller 3 are disposed within the vacuum chamber 2. The coating substrate 5 passes sequentially between the vacuum-sealed constant-speed roller 23 and the coating back roller 3, between the guide roller 4, and between the pressure roller 25 and the coating back roller 3; or as shown... Figure 6 As shown, the coating substrate introduction mechanism can also be a sealing member 27 disposed on the housing of the vacuum chamber 2 and pressed against the outer periphery of the coating back roller 3. In this case, the sealing member 27 and the outer periphery of the coating back roller 3 form a slit for the coating substrate 5 to pass through. The sealing member is a flexible member such as a rubber strip, silicone strip, or fluororubber strip. The coating substrate 5 passes between the sealing member 27 and the coating back roller 3.

[0044] In this embodiment, in order to enable the coating substrate 5 to be transported from the vacuum chamber 2 into the slurry chamber 1, a coating plate 18 (the coating plate 18 is part of the outer shell of the slurry chamber 1) is located on the side of the shell of the slurry chamber 1 near the vacuum chamber 2. A slurry gap E is formed between the coating plate 18 and the outer periphery of the coating back roller 3. This slurry gap E not only allows the coating substrate 5 to enter the slurry chamber 1 from the vacuum chamber 2, but also enables the coating substrate 5 to be coated in one pass. This is because the slurry gap E formed between the coating plate 18 and the coating back roller 3 has a vacuum chamber 2 on one side and a slurry chamber 1 on the other. The vacuum chamber 2 is a low-pressure vacuum environment. There is a pressure difference between the slurry chamber 1 and the vacuum chamber 2. Under the action of the pressure difference, the slurry in the slurry chamber 1 will flow from the slurry chamber 1 to the vacuum chamber 2 and flow into the slurry gap E area. During the process of the coating substrate 5 moving from the vacuum chamber 2 to the slurry chamber 1, the coating substrate 5 comes into contact with the slurry gap E first. At this time, both the slurry and the coating substrate 5 are in a low-pressure vacuum environment. When the high-viscosity paste slurry is coated on the coating substrate 5, it can effectively drive away the thin gas on the surface of the substrate. This solves the problem of pinholes, foil leakage, bubbles and other defects on the coating surface caused by the high-viscosity paste slurry not being able to drive away the gas on the surface of the coating substrate 5 in time in the existing secondary battery coating device.

[0045] A guide plate 14 is provided in the slurry chamber 1. The guide plate 14 can move along the movement direction of the coating substrate 5 under the drive of the guide plate driver 16. The guide plate 14 and the outer periphery of the coating back roller 3 form a guide plate gap D. The coating substrate 5, which has been coated once through the slurry gap E, will pass through the guide plate gap D under the drive of the coating back roller 3, thereby realizing the second coating of the coating substrate 5.

[0046] In this embodiment, the size of the guide plate gap D is controlled by driving the guide plate 14 to move through the guide plate driver 16. The value of the guide plate gap D ranges from 0.2mm to 15mm. The substrate carrying the slurry moves along the substrate movement direction and passes through the guide plate gap D.

[0047] In this embodiment, the end of the slurry chamber 1 away from the vacuum chamber 2 is provided with a discharge port 11. The discharge port 11 and the outer periphery of the coating back roller 3 also form a slit. Thus, the discharge port 11 can not only allow the coating substrate to be discharged from the slurry chamber 1, but also allow the coating substrate 5 to be coated three times. Under pressure, the excess slurry is guided back to the slurry chamber 1 by the guide plate 14.

[0048] To improve this embodiment, a slurry baffle 17 parallel to the movement direction of the coating substrate 5 is provided in the slurry chamber 1. Driven by a slurry baffle driver, the slurry baffle 17 moves away from or closer to the coating back roller 3. In this embodiment, the baffle 17 is made of a soft material and can also be a side baffle of the slurry chamber 1. During the coating process of the coating substrate 5, the baffle 17 is always present in the longitudinal direction from the slurry gap E to the outlet 11. That is, when the slurry baffle 17 is driven to press against the outer periphery of the coating back roller 3, the baffle 17 blocks the slurry, thereby controlling the formation of the coating substrate 5 as shown in the figure. Figure 3 The vertical blank area 61 is shown.

[0049] In this embodiment, a discharge port sealing plate 12 is also provided in the slurry chamber 1, which is arranged along the width direction of the coating substrate 5. The discharge port sealing plate 12 is located between the discharge port 11 and the guide plate 14 (the discharge port sealing plate 12 can also be arranged behind the discharge port 11), and is driven away from or close to the coating back roller 3 by the discharge port sealing plate driver. When the discharge port sealing plate 12 is driven to press against the outer periphery of the coating back roller 3, the discharge port sealing plate 12 blocks the slurry, thereby controlling the coating substrate 5 to form as shown in the figure. Figure 3 The horizontal blank area shown is 62.

[0050] The specific working process of this embodiment is as follows: To ensure the coating effect, slurry is fed into the slurry chamber 1 through the slurry inlet 15, ensuring that the slurry chamber above the coating substrate 5, corresponding to the position from the slurry gap E to the outlet 11, is filled with slurry, and maintaining a constant pressure within the slurry chamber 1. Then, the gas in the vacuum chamber 2 is continuously evacuated through the vacuum port 21 to form a low-pressure vacuum space. After the coating substrate 5 passes over the roller 4, as... Figure 1 As shown, it passes between the vacuum sealing constant speed roller 23 and the vacuum sealing roller 24, which are tangentially disposed on the housing of the vacuum chamber 2, and enters the vacuum chamber 2 (or as shown). Figure 4 As shown, it passes sequentially between the vacuum-sealed constant-speed roller 23 and the coating back roller 3, and between the pressure roller 25 and the coating back roller 3; or as... Figure 5 As shown, it passes sequentially between the vacuum-sealed constant-speed roller 23 and the coating back roller 3, through the guide roller 4, and between the pressure roller 25 and the coating back roller 3; or as... Figure 6 As shown, it passes between the sealing member and the coating back roller); thereafter, the coating substrate 5 begins to enter a next coating process, such as... Figure 3 As shown, the coating substrate 5 undergoes a first coating pass through the slurry gap E, and then the coating substrate 5, carrying the slurry, continues to move forward under the drive of the coating back roller 3. Afterwards, the coating substrate 5 begins the second coating process, as... Figure 3 As shown, the guide plate gap D exerts a squeezing force on the slurry. Under the dual squeezing action of pressure and guide plate gap D, the slurry is further coated and adhered to the coating substrate 5, which can fully fill the foil leakage area that was not fully coated in the first coating.

[0051] The coating substrate 5, carrying the slurry, continues to move along the substrate's movement direction. Afterward, the coating substrate 5 begins the three-pass coating process, such as... Figure 3 As shown, region F is formed between the discharge port 11 and the coating back roller 3. The shape of the discharge port in region F can be any shape among planar, arc-shaped, curved, or irregular. The discharge port gap G between the discharge port 11 and the coating back roller 3 is adjustable under the drive of the discharge port driver, and the value of G ranges from 0.01mm to 5mm. The included angle A between the discharge port 11 and the coating back roller 3 is defined as follows: one side of angle A is the tangent to the point on the coating back roller 3 closest to the discharge port 11, and the other side is the line connecting the point on the discharge port 11 closest to the coating back roller 3 and the second closest point on the discharge port 11 to the coating back roller 3. In this embodiment, the discharge port 11 is the outer wall of the slurry chamber 1. The external driver can control the size of A by driving the movement of the baffle constituting the discharge port 11, where the value of A ranges from 0° to 60°.

[0052] In this embodiment, a discharge port sealing plate 12 is provided, and the distance between the discharge port sealing plate 12 and the discharge port 11 is B, with B ranging from 0.1mm to 15mm. When the discharge port sealing plate 12 is controlled to approach the back roller 3 and make close contact with it under the drive of the discharge port sealing plate driver, the slurry on the coating substrate 5 is blocked in the slurry cavity 1, and the slurry cannot pass through the discharge port gap G, thus realizing the lateral blank area 62 of the electrode sheet 6. When the discharge port sealing plate 12 is controlled to leave the F area (i.e., the discharge port sealing plate driver controls the discharge port sealing plate 12 to move away from the back roller 3 and retract to expose the discharge port gap G), the slurry can pass through the discharge port gap G again. At this time, the F area generates a squeezing force on the slurry, and the coating substrate 5 carries the slurry through the F area. Excess slurry will return to the slurry cavity 1 through the F area.

[0053] In addition, a gap C is formed between the guide plate 14 and the discharge port 11. The size of the gap C can be controlled by controlling the movement of the guide plate 14 by the guide plate driver 16, thereby adjusting the coating lateral thickness. The value of the gap C is in the range of 0.01 to 15 mm. When the gap C decreases, the resistance of the slurry returning from below the discharge port 11 to the slurry chamber 1 increases, and the pressure on the slurry at the discharge port 11 increases. At this time, the amount of slurry passing through the gap G increases, and the coating thickness will increase accordingly. Conversely, when the gap C increases, the coating thickness will decrease accordingly. Finally, the coating substrate 5 in region F carries the slurry of the predetermined thickness and comes out from the discharge port gap G between the discharge port 11 and the coating back roller to form an undried electrode sheet 6.

[0054] Example 2: High-viscosity slurry coating device for secondary batteries

[0055] like Figure 7 , Figure 8As shown, the structure of this embodiment is basically the same as that of Embodiment 1. The difference is that, in order to achieve the vacuum effect of the vacuum chamber 2, four vacuum ports 21 for extracting gas are provided on the vacuum chamber 2 before the coating substrate 5 comes into contact with the slurry. During use, the gas in the vacuum chamber 2 is gradually extracted from each vacuum port 21 along the movement direction of the coating substrate 5, thereby forming a gradient vacuum region. The closer to the slurry, the higher the vacuum degree, and finally a vacuum environment is achieved in the contact area between the slurry and the substrate. Figure 7 , Figure 8 As shown, the infeeding mechanism includes an infeeding member disposed between two adjacent vacuum ports 21. The infeeding member is located on the housing of the vacuum chamber 2 and presses against the outer periphery of the coating back roller 3. The coating substrate 5 passes between the infeeding member and the coating back roller 3. The coating substrate infeeding member is a pressure roller 25 (or a sealing member 27 or a filler block can be selected; specifically, the sealing member 27 is a flexible member such as a rubber strip, silicone strip, or fluororubber strip, and the filler block is a rigid member made of stainless steel or aluminum alloy). Other structures in this embodiment are the same as in Embodiment 1 and will not be described again here.

[0056] Example 3: Method for Coating High-Viscosity Slurry for Secondary Batteries

[0057] This embodiment provides a method for coating high-viscosity slurry for secondary batteries, which is based on the high-viscosity slurry coating apparatus for secondary batteries provided in Embodiment 1.

[0058] In the coating method of this embodiment, the coating substrate 5 first undergoes a first coating pass through the slurry gap in a vacuum environment. At this time, the high-viscosity slurry can drive away the thin gas on the surface of the substrate 5 during the initial coating, which can effectively avoid problems such as pinholes, foil leakage, and bubbles caused by a large amount of gas on the surface of the coating substrate 5 during the coating process. Then, the coating substrate 5 undergoes a second coating pass through the gap of the adjustable guide plate, which can make the slurry coating of the coating substrate 5 more solid and effectively supplement the foil leakage areas that were not fully coated in the first pass. Finally, the coating substrate 5 undergoes a third coating pass through the outlet gap used to control the thickness of the coating slurry.

[0059] After the above three coating processes, the coating substrate 5 can be coated with a high-viscosity slurry to produce a smoother and more uniform electrode sheet.

[0060] In this embodiment, the gaps in the guide plate and the outlet can be adjusted by an external drive mechanism. The adjustment range of the guide plate gap is 0.2 to 15 mm, and the adjustment range of the outlet gap is 0.01 to 5 mm.

[0061] To improve this embodiment, after the coating substrate is coated through the guide plate gap or the outlet gap, a transverse blanking treatment step is set. During the coating process of the coating substrate from the slurry gap to the outlet gap, a longitudinal blanking treatment step is also set. The transverse blanking area 62 and the longitudinal blanking area 61 of the coating can be controlled according to the specific coating requirements.

[0062] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-viscosity slurry coating device for secondary batteries, characterized in that: It includes a coating back roller (3), on which a coating component is provided. The coating component has a cavity structure. The coating component and the outer periphery of the coating back roller (3) form a slit for coating the substrate. The coating component includes a vacuum chamber (2) and a slurry chamber (1). On the side of the shell of the slurry chamber (1) near the vacuum chamber (2) is a coating plate (18). A slurry gap is formed between the coating plate (18) and the outer periphery of the coating back roller (3). The slurry gap can realize one-pass coating of the substrate (5). The vacuum chamber (2) is provided with a vacuum port (21) for extracting gas. The end of the vacuum chamber (2) away from the slurry chamber (1) is provided with a coating substrate introduction mechanism. The slurry chamber (1) is provided with a slurry inlet (15) for injecting slurry. The shell of the end of the slurry chamber (1) away from the vacuum chamber (2) and the coating back roller (3) form an outlet (11) for recoating the coating substrate and exporting the coating substrate. The outlet (11) and the outer periphery of the coating back roller (3) form an outlet gap. The slurry chamber (1) is also provided with a guide plate (14) that moves along the direction of the coating substrate (5) under the drive of an external drive mechanism. The guide plate (14) and the outer periphery of the coating back roller (3) form a guide plate gap for secondary coating of the coating substrate. The coating substrate (5) is coated sequentially through a slurry gap in a vacuum environment and a discharge port gap used to control the thickness of the coating slurry, resulting in a uniformly coated electrode sheet. The discharge port gap is set based on the slurry chamber (1).

2. The coating apparatus according to claim 1, characterized in that: The slurry chamber (1) is provided with a slurry baffle (17) parallel to the direction of movement of the coating substrate (5). The length of the slurry baffle (17) extends from the slurry gap to the outlet (11). The slurry baffle (17) moves away from or close to the coating back roller (3) under the drive of the external drive mechanism, thereby controlling the coating substrate (5) to form a longitudinal blank area (61).

3. The coating apparatus according to claim 1, characterized in that: It also includes a discharge port sealing plate (12) arranged along the width direction of the coating substrate (5), the discharge port sealing plate (12) being located between the discharge port (11) and the guide plate (14) or behind the discharge port (11), and being driven away from or close to the coating back roller (3) by an external driving mechanism, thereby controlling the coating substrate (5) to form a transverse blank area (62).

4. The coating apparatus according to claim 1, characterized in that: The coating substrate introduction mechanism has one of the following structures: a. Includes a vacuum-sealed constant-speed roller (23) and a vacuum-sealed roller (24) tangentially disposed on the housing of the vacuum chamber (2), wherein the substrate (5) in the coating area passes between the vacuum-sealed constant-speed roller (23) and the vacuum-sealed roller (24); b. Includes a vacuum-sealed constant-speed roller (23) disposed on the housing of the vacuum chamber (2), wherein the vacuum-sealed constant-speed roller (23) is tangent to the coating back roller (3), and a pressure roller (25) tangent to the coating back roller (3) is disposed inside the vacuum chamber (2), and the coating substrate (5) passes sequentially between the vacuum-sealed constant-speed roller (23) and the coating back roller (3), and between the pressure roller (25) and the coating back roller (3); c. Includes a vacuum-sealed constant-speed roller (23) disposed on the housing of the vacuum chamber (2), wherein the vacuum-sealed constant-speed roller (23) is tangent to the coating back roller (3), and a passing roller (4) and a pressure roller (25) tangent to the coating back roller (3) are disposed in the vacuum chamber (2), and the coating substrate (5) passes sequentially between the vacuum-sealed constant-speed roller (23) and the coating back roller (3), between the passing roller (4), and between the pressure roller (25) and the coating back roller (3); d. Includes a sealing member (27) disposed on the housing of the vacuum chamber (2) and pressed against the outer periphery of the coating back roller (3), wherein the coating substrate (5) passes between the sealing member (27) and the coating back roller (3).

5. The coating apparatus according to claim 1, characterized in that: The vacuum port (21) includes at least two spaced apart on the vacuum chamber (2) along the direction of movement of the coating substrate (5); the inlet mechanism includes an inlet member disposed between two adjacent vacuum ports (21), the inlet member is disposed on the housing of the vacuum chamber (2) and presses against the outer periphery of the coating back roller (3), and the coating substrate (5) passes between the inlet member and the coating back roller (3).

6. The high-viscosity slurry coating device for secondary batteries according to claim 1, characterized in that: The gap between the guide plate (14) and the coating back roller (3) is 0.2-15mm, the gap between the discharge port (11) and the coating back roller (3) is 0.01-5mm, the distance between the discharge port sealing plate (12) and the discharge port (11) is 0.1mm-15mm, and the distance between the guide plate (14) and the discharge port (11) is 0.01-15mm.

7. The high-viscosity slurry coating apparatus for secondary batteries according to claim 1 or 6, characterized in that: The angle between the discharge port (11) and the coating back roller (3) is 0° to 60°.

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