Electrode coating apparatus and method

Abstract

The present application relates to an electrode coating apparatus and method that includes a turbulence generator to uniformize the velocity distribution of coating material transferred from a supply tank to an inlet of a slot die.

Description

[Technical field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0153050, filed with the Korean Intellectual Property Office on November 9, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to an electrode coating apparatus and an electrode coating method. [Background technology]

[0003] In recent years, the demand for environmentally friendly alternative energy sources has been increasing due to rising energy source prices caused by the depletion of fossil fuels and growing concern over environmental pollution. As a result, research into various power generation technologies such as atomic, solar, wind, and tidal power has been ongoing, and there is also a high interest in power storage devices to use the energy produced in this way more efficiently.

[0004] In particular, the demand for batteries as an energy source is increasing rapidly as technological development and demand for mobile devices increases, and much research is being conducted into batteries that can meet this demand.

[0005] Typically, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that are thin and can be applied to products such as mobile phones, etc. In terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0006] In general, a secondary battery includes an electrode assembly in which a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode are stacked. The positive electrode and the negative electrode are manufactured by coating an electrode slurry containing an active material on a current collector.

[0007] Among the methods for coating a current collector with a slurry containing an active material, a slot die has a high pressure at the center where the electrode slurry is injected, making it difficult to evenly apply the coating material.

[0008] Therefore, research is needed to uniformize the velocity distribution of the coating material being transferred from the supply tank to the inlet of the slot die. Summary of the Invention [Problem to be solved by the invention]

[0009] The present application provides an electrode coating apparatus and an electrode coating method. [Means for solving the problem]

[0010] One embodiment of the present application provides an electrode coating apparatus including a die coater that applies an electrode slurry onto a substrate, an injection port that supplies the electrode slurry to the die coater, a flow path having an end connected to the injection port so that the electrode slurry moves toward the die coater, and a turbulence generator that is provided within the flow path and generates turbulence in the electrode slurry moving along the flow path.

[0011] Yet another embodiment of the present application provides an electrode coating method using a die coater to apply an electrode slurry onto a substrate, the electrode coating method including the steps of: passing the electrode slurry through a turbulence generator before injecting the electrode slurry into the die coater to generate turbulence in the flow of the electrode slurry; injecting the electrode slurry that has passed through the turbulence generator into the die coater; and applying the electrode slurry onto a substrate with the die coater. Effect of the Invention

[0012] According to one embodiment of the electrode coating apparatus and method of the present application, the velocity distribution of the coating material transferred from the supply tank to the inlet of the slot die can be made uniform.

[0013] The electrode coating apparatus and method of one embodiment of the present disclosure reduces the width-wise variation of coating material transferred from a supply tank to the inlet of a slot die. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a schematic diagram showing an electrode coating apparatus. [Diagram 2] FIG. 2(a) is a perspective view and a vertical cross-sectional view of a turbulator having a mesh pattern according to one embodiment, and FIG. 2(b) is a perspective view and a vertical cross-sectional view of a turbulator having a honeycomb structure according to yet another embodiment. [Diagram 3] FIG. 2 is an exploded perspective view showing the electrode coating device. [Figure 4] FIG. 2 is a cross-sectional view of a conventional electrode coating apparatus showing the path of electrode slurry travel to the slot die tip and the flow velocity within the flow passage. [Diagram 5] FIG. 1 is a cross-sectional view of an electrode coating apparatus according to one embodiment, showing the path of electrode slurry travelling to the slot die tip and the change in flow velocity within the channel caused by turbulators. [Figure 6] FIG. 6(a) is a perspective view and a vertical cross-sectional view of a turbulator having a mesh pattern according to another embodiment, and FIG. 6(b) is a perspective view and a vertical cross-sectional view of a turbulator having a honeycomb structure according to yet another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the present invention will be described in detail with reference to the drawings. However, the drawings are for illustrating the present invention, and the scope of the present invention is not limited by the drawings.

[0016] 1 is a schematic diagram showing an electrode coating apparatus 100. The electrode coating apparatus 100 includes a supply tank 50, a die coater 10, an inlet 20, a flow path 30, and a turbulence generator 40. One end of the inlet 20 can be connected to a flow path 30 for the electrode slurry, through which the electrode slurry moves from the supply tank 50. By such connection, the flow path 30 through which the electrode slurry moves from the supply tank 50 to the die coater 10 is formed, and the turbulence generator 40 is provided within the flow path 30.

[0017] Fig. 3 is an exploded perspective view showing the electrode coating apparatus 100. As shown in Fig. 3, the injection port 20 is a pipe protruding from a side surface of the die coater, one end of the turbulence generator 40 is fastened to an end of the pipe, and the other end is fastened to an end of an electrode slurry supply pipe 60, and the flow path 30 may be a path through which the electrode slurry moving from the electrode slurry supply pipe passes through the turbulence generator and is injected into the pipe.

[0018] FIG. 2(a) is a perspective view and a vertical cross-sectional view of a turbulator having a mesh pattern according to one embodiment, and FIG. 2(b) is a perspective view and a vertical cross-sectional view of a turbulator having a honeycomb structure according to yet another embodiment.

[0019] The turbulence generator 40 is provided in the flow path 30. The turbulence generator 40 can be attached to the flow path 30 as an integrated module, or can be attached as a replaceable module and then separated. In particular, when the turbulence generator 40 is attached as a replaceable module, installation is simple, replacement is easy, and maintenance is easy. On the other hand, when the turbulence generator 40 is located inside the die coater 10, replacing the turbulence generator 40 in the die coater 10 requires dismantling and separating the die coater 10 or replacing the die coater 10 itself, which is troublesome.

[0020] The turbulence generator 40 generates turbulence in the electrode slurry moving along the flow path 30. It is preferable to select a shape that minimizes the pressure drop due to the addition of a structure in the flow path 30, and it is not preferable to use a shape that blocks the fluidity in the flow path 30, i.e., a plate that is not parallel to the flow direction. Specifically, if the turbulence generator 40 can form turbulence to the extent that the flow is divided by the additional structure, it can uniformize the velocity distribution while minimizing the pressure drop. In order to uniformize the velocity distribution while minimizing the pressure drop, the structure constituting the turbulence generator 40 is a thin metal thread or a plate provided parallel to the flow direction, and the moving electrode slurry 2 is influenced by the corners of the plate, i.e., the thickness of the plate, and the flow is divided, reducing the velocity variation.

[0021] As shown in the cross-sectional view of the conventional electrode coating device in Fig. 4, it can be seen that the flow rate of the electrode slurry 2 on the wall side of the flow path and the flow rate of the center part vary greatly as the electrode slurry 2 moves to the slot die tip. When the flow rate varies greatly, the pressure in the center part increases, and the electrode slurry 2 is not evenly applied onto the substrate 1.

[0022] In contrast, the electrode coating apparatus 100 according to the present invention includes a turbulence generator 40 to uniformize the velocity distribution of the coating material transferred to the inlet 20 of the slot die. Specifically, as shown in Fig. 5, when the electrode slurry 2 passes through the turbulence generator while moving to the slot die tip, the turbulence reduces the variation in flow rate, and the electrode slurry 2 with a uniform velocity distribution is more evenly applied.

[0023] The cross section of the turbulence generator 40 perpendicular to the longitudinal direction of the flow channel may be a pattern in which a number of polygons are adjacent to each other. Among the patterns in which a number of polygons are adjacent to each other, the polygons are planar figures having three or more vertices, and may have 3 to 10 vertices in particular. For example, the polygons may be triangles, quadrilaterals, pentagons, hexagons, etc.

[0024] The turbulators 40 may comprise plates forming the polygon or may comprise metal threads forming the polygon.

[0025] The plate may be a metal plate, and the material of the plate is not particularly limited as long as it can maintain sufficient strength to maintain the shape without affecting or being affected by the electrode slurry, but the material of the plate may be stainless steel such as SUS304. The thickness of the plate is not particularly limited as long as it can maintain sufficient strength to maintain the shape. For example, the thickness of the plate may be 0.1 mm or more and 10 mm or less.

[0026] The material of the metal thread is not particularly limited as long as it can maintain sufficient strength to maintain the shape without affecting the electrode slurry, but the material of the metal thread may be stainless steel such as SUS304. The thickness of the metal thread, i.e., the diameter of the vertical cross section in the longitudinal direction, is not particularly limited as long as it can maintain sufficient strength to maintain the shape. For example, the thickness of the metal thread may be 0.1 mm or more and 10 mm or less.

[0027] The cross section of the turbulator 40 perpendicular to the length of the flow passage may be a mesh pattern or a honeycomb structure, as shown in FIG.

[0028] As shown in FIG. 2(a), the cross section of the turbulence generator 40 perpendicular to the longitudinal direction of the flow path 30 is a mesh pattern. At this time, if the density of the mesh pattern is too high, i.e., if the area of ​​the square of the minimum unit 41 is too narrow, the pressure drop increases, so the density of the mesh pattern is preferably low. The area of ​​the square of the minimum unit 41 of the mesh pattern is 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, or 10% or more, and may be 20% or less, specifically, 10% or more and 20% or less, of the total area of ​​the cross section of the flow path 30. When this is satisfied, the flow rate by the turbulence generator can be made uniform while minimizing the pressure drop. In the cross section of the longitudinal direction of the flow path 30, the number of the minimum units 41, i.e., the number of squares, is 10 or less. Here, the number of the minimum units is the number of closed figures that maintain the shape of a repeated square.

[0029] 6(a), the number of minimum units 41, i.e., the number of rectangles, in the longitudinal cross section of the flow channel 30 may be 10. Here, the number of minimum units is the number of closed figures that maintain the shape of a repeated rectangle.

[0030] As shown in FIG. 2(b), the cross section of the turbulence generator 40 perpendicular to the longitudinal direction of the flow channel has a honeycomb structure. If the density of the honeycomb structure is too high, that is, if the area of ​​the hexagon of the minimum unit 41 is too narrow, the pressure drop increases, so it is preferable that the density of the honeycomb structure is low. Specifically, the area of ​​the hexagon of the minimum unit 41 of the honeycomb structure is 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, or 10% or more, and may be 20% or less, specifically, 10% or more and 20% or less, of the total area of ​​the cross section of the flow channel 30. If this is satisfied, the flow rate through the turbulence generator 40 can be made uniform while minimizing the pressure drop. In the cross section of the longitudinal direction of the flow channel 30, the number of the minimum units 41, that is, the number of hexagons, is 10 or less. Here, the number of the minimum units is the number of closed figures that maintain the shape of a repeated hexagon.

[0031] 6(b), in the longitudinal cross section of the flow channel 30, the number of minimum units 41, i.e., the number of hexagons, may be 7. Here, the number of minimum units is the number of closed figures that maintain the shape of a repeated hexagon.

[0032] The die coater 10 applies the electrode slurry 2 onto the substrate 1. The die coater includes a first die, a second die, and a shim between the first die and the second die so that the electrode slurry is discharged, and is provided with an inlet 20 for the electrode slurry penetrating at least one side of the first die and the second die. The inlet 20 may be a simple hole, or may protrude from the side of the die coater. The inlet 20 may be a pipe penetrating at least one side of the first die and the second die and protruding from the side.

[0033] One end of the inlet 20 may be connected to a supply pipe 60 for electrode slurry, through which the electrode slurry moves from the supply tank 50. This connection forms a flow path 30 through which the electrode slurry moves from the supply tank 50 to the die coater 10. In this flow path, a turbulence generator 40 may be provided in a pipe protruding from a side surface of the die coater or in the supply pipe 60 for the electrode slurry.

[0034] Another embodiment of the present application provides an electrode coating method using a die coater 10 to apply an electrode slurry 2 onto a substrate 1, the method including the steps of: generating turbulence in the flow of the electrode slurry by passing the electrode slurry through a turbulence generator 40 before injecting the electrode slurry into the die coater 10; injecting the electrode slurry that has passed through the turbulence generator into the die coater 10; and applying the electrode slurry 2 onto the substrate 1 with the die coater 10.

[0035] For the description of the electrode coating method, the description of the electrode coating apparatus can be cited.

[0036] Those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features of the present invention. Therefore, the above-described embodiment is illustrative in all respects and is not limiting. The scope of the present invention is indicated by the claims rather than the above detailed description, and various embodiments derived from the gist and scope of the claims and their equivalent concepts are to be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0037] 1: Base material 2: Electrode slurry 10: Die coater 20: Inlet 30: Flow path 40: Turbulence generator 41: Smallest unit 50: Supply tank 60: Electrode slurry supply pipe 100: Electrode coating device

Claims

1. A die coater that applies electrode slurry onto the substrate; an inlet for supplying the electrode slurry to the die coater; A flow path having an end connected to the inlet so that the electrode slurry moves toward the die coater; and a turbulence generator provided within the flow path for generating turbulence in the electrode slurry moving along the flow path; a cross section of the turbulator perpendicular to the longitudinal direction of the flow passage has a pattern of adjacent polygons; The turbulence generator comprises plates defining the polygon and arranged parallel to the longitudinal direction of the flow passage.

2. 2. The electrode coating apparatus of claim 1, wherein a cross section of the turbulator perpendicular to the longitudinal direction of the flow passage has a mesh pattern or a honeycomb structure.

3. The injection port is a pipe protruding from a side surface of the die coater, One end of the turbulence generator is fastened to an end of the pipe, and the other end is fastened to an end of a supply pipe for electrode slurry, 2. The electrode coating apparatus according to claim 1, wherein the flow path is a path through which the electrode slurry moving from a supply pipe for the electrode slurry passes through the turbulence generator and is injected into the piping.

4. An electrode coating method using a die coater to apply an electrode slurry onto a substrate, comprising the steps of: generating turbulence in the flow of the electrode slurry by passing the electrode slurry through a turbulence generator before injecting the electrode slurry into the die coater; injecting the electrode slurry that has passed through the turbulence generator into the die coater; and applying the electrode slurry onto the substrate with the die coater; A cross section of the turbulence generator perpendicular to a longitudinal direction of a flow path has a pattern in which a number of polygons are adjacent to each other so that the electrode slurry moves to the die coater side, The turbulence generator comprises plates defining the polygon and arranged parallel to the longitudinal direction of the flow passage.

5. 5. The method of claim 4, wherein the cross section of the turbulator is a mesh pattern or a honeycomb structure.

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