Slot die with split manifold

Abstract

The disclosed slot die includes a first body having a plurality of manifolds divided to contain electrode slurry independently and in isolation from one another, a second body pressurized and fastened to the first body to maintain airtightness of the plurality of manifolds, and a coater shim tightly interposed between the first body and the second body to form a plurality of slits between the joining surfaces of the first body and the second body that communicate with the plurality of manifolds.

Description

[Technical Field]

[0001] The present invention relates to a slot die for applying an active material onto a current collector for a secondary battery.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0113882, filed on August 29, 2023, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0003] The demand for secondary batteries is also increasing rapidly due to technological developments and increased demand for mobile devices. Among them, lithium secondary batteries are widely used as an energy source for various electronic products as well as various mobile devices due to their high energy density, operating voltage, and excellent storage and life characteristics.

[0004] Lithium secondary batteries use electrodes in which an active material layer and an insulating layer are formed on the surface of a current collector. Such electrodes are produced by applying an electrode slurry containing the active material and an insulating coating liquid containing the insulating material to the surface of a current collector using a coating device such as a slot die, followed by drying.

[0005] Figure 1 shows a conventional slot die 1 for applying electrode slurry. The slot die 1 includes an upper block 2 and a lower block 3, with a coater shim 4 interposed between the upper block 2 and the lower block 3, and the upper block 2 and the lower block 3 fastened together by a plurality of bolt members. The lower block 3 is provided with a manifold 5, which is a recessed space that contains the electrode slurry, and the manifold 5 is connected to an external electrode slurry supply unit (not shown) by piping.

[0006] The slot die 1 shown in Figure 1 is a single-lane type in which electrode slurry is discharged in a single line. In contrast, Figure 2 shows a multi-lane type slot die 1' in which electrode slurry is discharged in multiple lines. The coater shim 4' provided in the slot die 1' in Figure 2 has multiple branches 6 extending across the manifold 5 as well as on both sides of the manifold 5. This forms multiple lanes between the branches 6 protruding from the tip of the manifold 5.

[0007] However, with multi-lane slot dies like the one shown in Figure 2, it is difficult to maintain uniformity in the amount of electrode slurry dispensed between each lane. This is due to factors such as the flow pressure of the electrode slurry acting on each lane, bending or twisting of the slot die due to its large size, and differences in the placement of the coater shim between operators. When differences in the amount of electrode slurry dispensed between lanes occur, the coating loading amount and coating width of the current collector become locally non-uniform, ultimately adversely affecting the quality of secondary batteries. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to make it possible to form a uniform local coating amount and coating width across all lanes of a slot die.

[0009] Another object of the present invention is to solve the problem of differences in the installation of coater shims between different workers.

[0010] However, the technical problems that the present invention aims to solve are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the description of the invention described below. [Means for solving the problem]

[0011] The present invention relates to a slot die, and in one example, includes a first body having a plurality of manifolds divided to contain electrode slurry independently and in isolation from one another, a second body pressurized and fastened to the first body to maintain airtightness of the plurality of manifolds, and a coater shim tightly interposed between the first body and the second body to form a plurality of slits communicating with the plurality of manifolds between the joining surfaces of the first body and the second body.

[0012] In the slot die of the present invention, the plurality of slits are assigned to each of the manifolds so as to communicate with any one of the plurality of manifolds.

[0013] In one embodiment of the present invention, the coater shim may include a base shim that seals the rear ends and both side surfaces of the plurality of manifolds, and a plurality of spacer shims that are spaced apart to form the plurality of slits at the front ends of the plurality of manifolds.

[0014] Here, some of the spacer shims may be disposed corresponding to at least one partition wall that separates the manifolds from one another.

[0015] The slot die of the present invention includes a slurry pipe that supplies slurry to the plurality of manifolds, and the slurry pipe includes a main pipe consisting of a single pipe, a buffer pipe that stores a certain volume of the electrode slurry supplied from the main pipe, a plurality of branch pipes that are branched and connected from the buffer pipe so as to correspond to the number of the plurality of manifolds, and a plurality of flow control valves provided for each of the branch pipes.

[0016] The plurality of flow control valves are independently controlled in terms of opening amount to the corresponding manifolds so as to reduce the difference in slurry loading in the width direction of the electrode where the plurality of slits are aligned.

[0017] In one embodiment of the present invention, the plurality of flow control valves may be independently controlled to have their openings controlled so that the slurry flow rate is symmetrical with respect to the plurality of manifolds, with respect to the center of the plurality of slits arranged in a row.

[0018] In addition, the plurality of flow control valves may be controlled so that the opening amount of the manifold located at the center of the plurality of manifolds is the largest or smallest.

[0019] The first body may be provided with a plurality of fixing pins at mounting positions of the spacer shim, and the spacer shim may be provided with a plurality of holes into which the fixing pins are inserted.

[0020] The spacer shim may include an insulating liquid supply hole through which an insulating liquid is supplied, and a groove connected to the insulating liquid supply hole and extending to a tip of the spacer shim. [Effects of the Invention]

[0021] The slot die of the present invention having the above-described configuration includes a plurality of manifolds connected to a plurality of slits, thereby allowing for different flow rates of electrode slurry supplied to each manifold. Since the discharge rate of electrode slurry can be independently controlled for each group of slits assigned to each manifold, it is possible to adjust the difference in coating loading and coating width occurring along the width direction of the current collector, thereby improving the quality of secondary batteries.

[0022] The slot die of the present invention has a plurality of fixing pins on the first body corresponding to the mounting position of the spacer shim, and a plurality of holes in the spacer shim into which the fixing pins are inserted. This pin and hole configuration allows the spacer shim to be installed consistently without any operator intervention, thereby eliminating the problems of differences in coating loading and coating width due to inconsistent spacer shim installation.

[0023] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the invention described below.

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters depicted in such drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing an example of a slot die according to the prior art. [Figure 2] 1 is a diagram showing an example of a slot die according to the prior art. [Figure 3] 1 is an exploded view showing a first body and a second body of a slot die according to an embodiment of the present invention. [Figure 4] FIG. 10 is a plan view showing a structure in which a coater shim is attached to a first body. [Figure 5] 1 is a diagram illustrating an embodiment of a slot die including slurry piping. [Figure 6] 10 is a diagram showing an example of a slurry loading profile depending on the opening amount of each flow control valve for three manifolds. [Figure 7] 1 is a view showing an embodiment of a structure for mounting a spacer shim to a first body. DETAILED DESCRIPTION OF THE INVENTION

[0026] Because the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0027] However, this is not intended to limit the invention to any particular embodiment, but is to be understood as including all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0028] In the present invention, the terms "comprise" and "have" are understood to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, without precluding the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0029] Furthermore, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion between them. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion between them. Furthermore, in the present application, being disposed "on" can include not only the case where it is disposed at the top, but also the case where it is disposed at the bottom.

[0030] The present invention relates to a slot die, and in one example, includes a first body having a plurality of manifolds divided to contain electrode slurry independently and isolated from one another, a second body pressurized and fastened to the first body to maintain airtightness of the plurality of manifolds, and a coater shim tightly interposed between the first body and the second body to form a plurality of slits between the joining surfaces of the first body and the second body that communicate with the plurality of manifolds.

[0031] As described above, the slot die of the present invention includes a plurality of manifolds connected to a plurality of slits, thereby allowing for different flow rates of electrode slurry supplied to each manifold. Since the discharge rate of electrode slurry can be independently controlled for each group of slits assigned to each manifold, it is possible to adjust the difference in coating loading and coating width occurring along the width direction of the current collector, thereby improving the quality of secondary batteries.

[0032] Hereinafter, a specific embodiment of the slot die 10 according to the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front and back, up and down, left and right, and the like used in the following description to specify relative positions are intended to aid in understanding the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0033] (First embodiment) 3 is an exploded view showing the first body 100 and the second body 200 of the slot die 10 according to one embodiment of the present invention. Referring to FIG. 3, the slot die 10 of the present invention includes the first body 100 and the second body 200 that are fastened to each other, and a coater shim 300 that is interposed between the first body 100 and the second body 200.

[0034] The first body 100 is a lower block of the slot die 10 and includes a manifold 110 that receives electrode slurry supplied from the outside. In particular, in the slot die 10 of the present invention, the manifold 110 provided in the first body 100 is composed of a plurality of manifolds 110 separated by partition walls 112, and each manifold 110 receives electrode slurry independently and in isolation from the others. That is, the electrode slurry received in each manifold 110 cannot move to another adjacent manifold 110.

[0035] The second body 200 is an upper block of the slot die 10 and is pressurized and fastened to the first body 100 so as to maintain airtightness of the plurality of manifolds 110 provided in the first body 100. For example, the first body 100 and the second body 200 can be firmly coupled to each other by a plurality of bolts 210 that penetrate the second body 200 and are screwed into the first body 100.

[0036] The coater shim 300 is closely interposed between the first body 100 and the second body 200, and forms a plurality of slits 350 at the tip of the slot die 10 (here, the tip refers to the end from which the electrode slurry is dispensed). The coater shim 300, which is closely interposed between the joining surfaces of the first body 100 and the second body 200 that are fastened together under pressure, has a predetermined thickness, and the coater shim 300, which is divided and disposed at the tip of the slot die 10, forms a plurality of slits 350. Each slit 350 forms a lane through which the electrode slurry is dispensed in a line onto the surface of the current collector.

[0037] In the illustrated embodiment, the first body 100 is provided with three manifolds 110, and the coater shim 300 is composed of one base shim 310 and a plurality of spacer shims 320. The base shim 310 seals the rear ends and both sides of the manifolds 110, and the spacer shims 320 are spaced apart at the front ends of the manifolds 110 to form a plurality of slits 350. In this embodiment, the base shim 310 only serves to seal the rear ends and both sides of the manifolds 110, and only the spacer shims 320 are involved in forming the slits 350. Therefore, in an embodiment in which the coater shim 300 is divided into the base shim 310 and a plurality of spacer shims 320, it is possible to replace or adjust only the spacer shim 320 that is causing problems in slurry loading control, thereby enabling localized loading control and advantageously saving costs and time associated with changing the coater shim 300.

[0038] 4 is a plan view showing a structure in which the coater shim 300 is attached to the first body 100. FIG. 4 shows in detail the relationship between the manifold 110 and the coater shim 300, particularly the positional relationship between the multiple manifolds 110 and the multiple spacer shims 320. As shown in the figure, multiple slits 350 are assigned to each manifold 110 so as to communicate with any one of the multiple manifolds 110. In other words, at least one slit 350 is connected to each manifold 110. One slit 350 is connected to only one manifold 110, and multiple slits 350 can be connected to one manifold 110 as shown in the figure.

[0039] If a plurality of slits 350 sharing one manifold 110 is considered to be one group of slits 350, then in the illustrated embodiment, three manifolds 110 are provided, and therefore the plurality of slits 350 are divided into three groups of slits 350. Because the plurality of manifolds 110 are completely separated from one another, it is possible to adjust the flow rate of electrode slurry supplied to each manifold 110 differently, and as a result, it is possible to independently control the discharge rate of electrode slurry for each group of slits 350 assigned to each manifold 110. By controlling the discharge rate of slurry for each group of slits 350, it is possible to adjust the difference in coating loading amount and coating width that occurs along the width direction of the current collector, thereby improving the quality of the secondary battery.

[0040] Here, in order for one slit 350 to be connected to only one manifold 110, it is necessary to take into consideration the partitions 112 that separate the multiple manifolds 110. That is, some of the multiple spacer shims 320 need to be disposed corresponding to at least one partition 112 that separates the multiple manifolds 110 from one another. The width of the spacer shim 320 is designed to be at least equal to the thickness of the partition 112. Thus, when one end of the spacer shim 320 is attached to face the partition 112, both sides of the spacer shim 320 contact different manifolds 110, and as a result, the two slits 350 located on both sides of the spacer shim 320 are connected to different manifolds 110.

[0041] 5 is a diagram showing one embodiment of the slot die 10 including a slurry pipe 400. The slurry pipe 400 is a pipe that supplies slurry to multiple manifolds 110, and in the illustrated embodiment, the slurry pipe 400 includes a main pipe 410, a buffer pipe 420, multiple branch pipes 430, and multiple flow control valves 440.

[0042] The main pipe 410 may be a single pipe through which electrode slurry is supplied from the outside. A buffer pipe 420 is connected to the outlet of the main pipe 410. The buffer pipe 420 serves to accommodate a certain volume of the electrode slurry supplied from the main pipe 410 and buffers the fluctuation and strength of the slurry flow generated in the slot die 10. A plurality of branch pipes 430, each assigned to each of the plurality of manifolds 110, are connected to the buffer pipe 420, and a flow control valve 440 is installed on each branch pipe 430. That is, each manifold 110 is provided with one branch pipe 430 and one flow control valve 440, and the opening of the flow control valve 440 is controlled to adjust the flow rate of the electrode slurry. For reference, the drawing does not show the control unit that controls the opening amount of the flow control valve 440, but since the configuration of the control unit that controls the opening amount of the valve falls within the category of well-known commonly used technology, the omission of illustrations and explanations thereof does not hinder understanding of the present invention.

[0043] The openings of the flow control valves 440 for the corresponding manifolds 110 are independently controlled to reduce differences in slurry loading across the width of the electrode where the slits 350 are aligned. That is, if there are differences in the amount of slurry loading across the group of slits 350 assigned to each manifold 110, the openings of the flow control valves 440 installed in each manifold 110 are controlled differently to take such differences into account, thereby enabling uniform slurry loading across the entire width of the electrode.

[0044] Generally, the design of the slot die 10, specifically, the arrangement of the slurry pipes 400 and the pressure fastening structure of the first body 100 and the second body 200, is symmetrical with respect to the center of the width of the slot die 10. As a result, in most cases, the slurry loading profile is generally symmetrical with respect to the center of the width of the slot die 10. In consideration of this phenomenon, the plurality of flow control valves 440 may be independently controlled to have their openings adjusted to the plurality of manifolds 110 such that the slurry flow rates are symmetrical with respect to the center of the plurality of slits 350 arranged in a row. For example, the plurality of flow control valves 440 may be controlled to have the largest or smallest opening with respect to the manifold 110 located in the center of the plurality of manifolds 110.

[0045] 6 is a diagram showing an example of a slurry loading profile according to the opening amount of each flow control valve 440 for three manifolds 110. As shown in the actual measurement data in FIG. 6, the opening amount of the flow control valve 440 for the central manifold 110 is set to the largest according to the optimal opening amount indicated in blue, and the opening amounts of the manifolds 110 on the left and right sides are set to be smaller and symmetrical, thereby achieving fairly uniform slurry loading across the entire width of the slot die 10.

[0046] In this specification, the multiple manifolds 110 are exemplified as an embodiment of a three-split manifold, but it should be noted that the slot die 10 of the present invention can be embodied in various embodiments including multiple manifolds 110 split into two, four or more, or even more.

[0047] (Second embodiment) In the first embodiment, a configuration was described in which the opening amounts of the multiple flow control valves 440 assigned to the multiple divided manifolds 110 are optimized to ensure uniform slurry loading along the width direction of the slot die 10.

[0048] In one embodiment of the present invention, the coater shim 300 may have a divided structure consisting of a base shim 310 and a plurality of spacer shims 320. This divided coater shim 300 structure allows only the problematic spacer shim 320 to be replaced or adjusted, thereby enabling localized control of slurry loading and reducing the cost and time required to change the coater shim 300.

[0049] However, because the coater shim 300 has a divided structure, the installation of the spacer shim 320, which is directly related to slurry loading, is important, and differences in the installation of the spacer shim 320 may occur depending on the operator. Since differences in the installation of the spacer shim 320 lead to differences in the slurry loading, it is necessary to optimize the opening amount of the flow control valve 440 and solve the problem of differences in the installation of the spacer shim 320. The second embodiment of the present invention relates to a structure that allows the spacer shim 320 to be installed consistently without being affected by the operator.

[0050] 7 is a view showing one embodiment of a structure for mounting spacer shims 320 to a first body 100. Referring to FIG. 7, the first body 100 is provided with a plurality of fixing pins 120 corresponding to the mounting positions of the spacer shims 320, and the spacer shims 320 are formed with a plurality of holes 322 into which the fixing pins 120 are inserted.

[0051] At least two fixing pins 120 are provided, and in the illustrated embodiment, three are provided. When arranging multiple fixing pins 120 in this manner, it is preferable that when the spacer shim 320 is attached, it can be maintained in its attached position without rotating, and that it can be attached in only one direction, either front-to-back, left-to-right, or up-to-down.

[0052] 7, the end of the fixing pin 120 protrudes slightly above the hole 322 of the spacer shim 320. If the height of the fixing pin 120 is made slightly greater than the thickness of the spacer shim 320, a shallow hole (not shown) into which the end of the fixing pin 120 fits must also be formed in the coupling surface of the second body 200. In this case, the fixing pin 120 serves to align the coupling position of the second body 200 relative to the first body 100.

[0053] In some embodiments, the slot die 10 may be configured to dispense an insulating liquid along with the electrode slurry. To this end, as shown in FIG. 7 , a spacer shim 320 includes an insulating liquid supply hole 324 through which the insulating liquid is supplied, and a groove 326 connected to the insulating liquid supply hole 324 and extending to the tip of the spacer shim 320. The end of the groove 326 extending from the insulating liquid supply hole 324 is open. Therefore, the electrode slurry is dispensed through a slit 350 formed between the spacer shims 320, while the insulating liquid is dispensed adjacent to the edge of the electrode slurry. By applying the insulating liquid to both sides of the electrode slurry, sliding at the edge of the electrode slurry is controlled, improving insulation performance.

[0054] The grooves 326 provided in the spacer shims 320 may be straight or U-shaped. A straight groove 326-1 may be provided on each outermost spacer shim 320 in the width direction of the slot coater, and U-shaped grooves 326-2 may be provided on the other spacer shims 320. This depends on whether the slits 350 are arranged on one or both sides of the spacer shims 320 in the width direction.

[0055] The insulating liquid is supplied to the insulating liquid supply holes 324 of the spacer shim 320 through an insulating liquid flow path (not shown) formed inside the first body 100 or the second body 200. The spacer shim 320 may also have bolt holes 328 through which the bolts 210 pass. A plurality of bolts 210 passing through the first body 100 are fastened to the second body 200 to pressurize the first body 100 and the second body 200 together, and some of the bolts 210 may pass through the spacer shim 320. By positioning the spacer shim 320 at the point where the fastened bolts 210 apply pressure, the strength with which the upper and lower surfaces of the spacer shim 320 adhere to the second body 200 and the first body 100 is improved, thereby effectively preventing the electrode slurry and the insulating liquid from leaking or mixing from the joining surfaces of the first body 100 and the second body 200.

[0056] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations shown in the drawings or embodiments in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore, at the time of filing this application, there may be various equivalents and modifications that can replace them. [Explanation of symbols]

[0057] 10: Slot die 100: First body 110: Manifold 112: Bulkhead 120: Fixing pin 200: Second body 210: Bolt 300: Coater shim 310: Base shim 320: Spacer shim 322: Hole 324: Insulating liquid supply hole 326: Groove 326-1: Single-shaped groove 326-2: U-shaped groove 328: Bolthole 350:Slit 400: Slurry piping 410: Main piping 420: Buffer piping 430: Branch piping 440: Flow control valve

Claims

1. a first body provided with a plurality of manifolds divided to contain electrode slurries independently and in isolation from one another; a second body that is pressure-fastened to the first body so as to maintain airtightness of the plurality of manifolds; a coater shim tightly interposed between the first body and the second body to form a plurality of slits communicating with the plurality of manifolds between the joining surfaces of the first body and the second body.

2. The slot die according to claim 1 , wherein the plurality of slits are assigned to communicate with any one of the plurality of manifolds.

3. The coater shim is a base shim sealing the rear ends and both side surfaces of the plurality of manifolds; 3. The slot die of claim 2, further comprising: a plurality of spacer shims spaced apart to form the plurality of slits at the tips of the plurality of manifolds.

4. The slot die of claim 3 , wherein some of the spacer shims are positioned corresponding to at least one partition wall separating the manifolds from one another.

5. further comprising a slurry pipe for supplying slurry to the plurality of manifolds; The slurry piping is a main pipe consisting of a single pipe; a buffer pipe for accommodating a certain volume of the electrode slurry supplied from the main pipe; a plurality of branch pipes branched and connected from the buffer pipe so as to correspond to the number of the plurality of manifolds; The slot die according to claim 1 , further comprising: a plurality of flow control valves provided for each of the plurality of branch pipes.

6. The slot die according to claim 5, wherein the plurality of flow control valves independently control the opening amounts for the corresponding manifolds so as to reduce differences in slurry loading in the width direction of the electrode in which the plurality of slits are aligned.

7. The slot die according to claim 6, wherein the plurality of flow control valves independently control the opening amounts of the plurality of manifolds so that the slurry flow rates are symmetrical with respect to the center of the plurality of slits arranged in a row.

8. The slot die according to claim 7 , wherein the plurality of flow control valves control the opening amount of a manifold located at the center of the plurality of manifolds to the largest or smallest.

9. The first body is provided with a plurality of fixing pins at mounting positions of the spacer shims, The slot die of claim 3 , wherein the spacer shim has a plurality of holes through which the fixing pins are inserted.

10. The spacer shim includes: an insulating liquid supply hole through which insulating liquid is supplied; 4. The slot die according to claim 3, further comprising a groove connected to the insulating liquid supply hole and extending to a tip of the spacer shim.

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