Dual slit die for simultaneous electrode paste and insulating solution coating and coating method using the same

Abstract

The present invention relates to a double slit die and a coating method using the same, wherein the following advantages are provided: electrode slurry coating and insulating solution coating are simultaneously performed by the double slit die to prevent electrode slurry slip at the edges of the electrode slurry layer, and the electrode slurry layer and the insulating layer can be formed on a current collector sheet in a multi line manner by including a shim having a structure in which a plurality of discharge lines capable of discharging electrode slurry or insulating solution in a multi line manner are formed, thereby increasing process efficiency.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application No. 10-2021-0167169 dated November 29, 2021 and Korean Patent Application No. 10-2022-0090580 dated July 21, 2022, all of which are incorporated herein by reference.

[0002] This invention relates to a double-slit mold for simultaneously applying electrode slurry and insulating solution, and a coating method using the double-slit mold. Background Technology

[0003] With technological advancements and the growing demand for mobile devices, the demand for rechargeable batteries is also rapidly increasing. Among rechargeable batteries, lithium-ion batteries have been widely used as energy sources for various electronic products and mobile devices due to their high energy density, high operating voltage, and excellent storage and lifespan characteristics.

[0004] Typically, there is a high demand for prismatic and pouch batteries that are thinner in terms of battery shape and can be used in products such as mobile phones, as well as for lithium secondary batteries (such as lithium cobalt polymer batteries) with excellent energy density, discharge voltage and material-based safety.

[0005] One of the main research tasks for this type of secondary battery is to improve safety. A major cause of safety-related accidents in batteries is the abnormally high temperature caused by a short circuit between the positive and negative electrodes. That is, under normal circumstances, the separator is located between the positive and negative electrodes to maintain electrical insulation, but under abnormal operating conditions, such as overcharging or over-discharging of the battery, internal short circuits may occur due to dendritic growth of the electrode material or foreign objects, or the battery may deform due to external forces when sharp objects such as nails and screws penetrate the battery. The existing single separator shows its limitations.

[0006] Typically, microporous membranes made of polyolefin resin are used as separators, but their heat resistance is only about 120°C to 160°C, which is insufficient. Therefore, when an internal short circuit occurs, the following problem arises: the separator contracts due to the heat of the short circuit reaction, causing the positive and negative plates to come into contact with each other, which amplifies the short circuit portion inside the battery and generates a larger amount of heat of reaction, resulting in thermal runaway.

[0007] Typically, a prismatic secondary battery is manufactured by cutting the positive and negative electrodes to predetermined dimensions and overlapping several pieces of positive and negative electrodes. In this case, the edges of the positive or negative electrodes coated with polymer electrolyte have inconspicuous, very small, needle-like sharp portions. The stacking of electrodes can cause tiny internal short circuits in these portions, adversely affecting battery performance. In particular, even when the edges are coated with polymer electrolyte, the irregular surfaces at the edges prevent uniform coating, resulting in a higher probability of short circuits. Furthermore, even small deviations between the lower and upper electrodes during electrode stacking can cause short circuits between the positive and negative electrodes.

[0008] Therefore, various methods have been investigated to reduce the possibility of battery deformation, external impact, or physical short circuits between the positive and negative electrodes. For example, one method involves attaching an insulating tape of a predetermined size to the electrode contacts adjacent to the top of the current collector to prevent the electrode contacts from contacting the upper end of the electrode assembly and causing a short circuit when the electrode assembly is moved during battery assembly. However, the winding operation of this insulating tape is very complex, and when the insulating tape is wound to a length that extends slightly downward from the top of the current collector, this portion can cause an increase in the thickness of the electrode assembly. Typically, as described above, the method of attaching insulating tape to the electrode contacts employs a method in which an electrode paste is applied to the positive electrode and an insulating solution is applied to the area where no electrode paste is applied (i.e., the uncoated area).

[0009] On the other hand, as a method for uniformly coating an electrode active material slurry onto a current collector plate, a slot die coating process is typically performed. Furthermore, a slot die coating process is performed to coat the electrode active material slurry and an insulating solution onto the current collector plate. In this case, to coat the electrode active material slurry and the insulating solution onto the current collector plate, there exists a coating process that uses a slot die to coat the electrode active material slurry and a separate slot die to coat the insulating solution.

[0010] Figure 1 It is a schematic diagram illustrating the formation of electrode paste layer and insulating layer on current collector plate in a conventional manner using separate electrode paste coating slit molds and separate insulating solution coating slit molds.

[0011] See Figure 1 Electrode paste 30 can be applied to current collector sheet 16 moving along coating roller 15 by electrode paste coating slit mold 100 consisting of two blocks, and insulating solution 31 can be applied by a separate insulating solution coating slit mold 110 to have a constant width from the edge of electrode paste layer formed on current collector sheet 16.

[0012] However, the coating process using the conventional slit mold described above has the problem of reduced quality. During the movement of the current collector 16, coated with electrode paste 30, along the coating roller 15 via the electrode paste coating slit mold 100, undesirable electrode paste 30 slippage occurs at the edges of the electrode paste layer. Furthermore, when the distance between the electrode paste coating slit mold 100 and the insulating solution coating slit mold 110 increases, undesirable problems such as current collector 16 breakage or camber occur. Additionally, the separate operation of the electrode paste coating slit mold 100 and the insulating solution coating slit mold 110 reduces manufacturing efficiency and makes it difficult to precisely control the width and thickness of the electrode paste coating and the insulating solution coating.

[0013] Therefore, there is a need for effective methods to improve these problems. Summary of the Invention

[0014] Technical issues

[0015] The present invention was designed to solve the above-mentioned problems, and the object of the present invention is to provide a double-slit mold capable of simultaneously applying electrode paste and insulating solution to prevent electrode paste slippage at the edge of the electrode paste layer applied to the current collector sheet, and a coating method using the double-slit mold.

[0016] Technical solution

[0017] This invention provides a double-slit mold. In one example, the double-slit mold according to the invention is a double-slit mold comprising a lower block, a middle block, and an upper block, the double-slit mold comprising: a lower gasket located between the lower block and the middle block; an upper gasket located between the middle block and the upper block; a lower manifold formed in the lower block to store electrode paste; and an upper manifold formed in the upper block to store an insulating solution, the electrode paste stored in the lower manifold being branched and discharged into n rows by an electrode paste discharge line formed in the lower gasket, and the insulating solution stored in the upper manifold being branched and discharged into 2n rows by an insulating solution discharge line formed in the upper gasket, where n is an integer of 1 or greater. For example, n is an integer in the range of 1 to 10, or from 1 to 5.

[0018] In one specific example, in the double-slit mold according to the invention, the angle at which the first plane extending from the upper gasket intersects the second plane extending from the lower gasket forms an angle in the range of 20° to 60°.

[0019] In another specific example, the double-slit mold according to the invention may have a structure in which the width of the electrode slurry discharge portion and the width of the insulating solution discharge portion do not overlap with each other in the direction perpendicular to the cross section of the upper gasket, the electrode slurry discharge portion being the opening portion of the electrode slurry discharge line, and the insulating solution discharge portion being the opening portion of the insulating solution discharge line.

[0020] In another specific example, in the double-slit mold according to the invention, the width of the electrode slurry discharge portion and the width of the insulating solution discharge portion overlap each other in the vertical direction of the cross-section of the upper gasket, and the overlap range is from 5% to 30% of the width of the insulating solution discharge portion, wherein the electrode slurry discharge portion is the opening portion of the electrode slurry discharge line, and the insulating solution discharge portion is the opening portion of the insulating solution discharge line. The overlap range means that the area where the electrode slurry discharge portion and the insulating solution discharge portion overlap in the width direction is based on a ratio of 100% of the length of the insulating solution discharge portion in the width direction.

[0021] In another example, in the double-slit mold according to the invention, in the direction of applying electrode slurry and insulating solution to the current collector sheet, the electrode slurry discharge portion is located upstream, the electrode slurry discharge portion being the opening portion of the electrode slurry discharge line, the insulating solution discharge portion is located downstream, the insulating solution discharge portion being the opening portion of the insulating solution discharge line, and further includes a UV lamp located downstream of the insulating solution discharge portion.

[0022] Furthermore, the present invention provides a coating method using the double-slit mold described above. In one embodiment, the coating method according to the present invention is a coating method for applying electrode slurry and insulating solution to a current collector sheet using a double-slit mold, the double-slit mold comprising a lower block, a middle block, and an upper block, the method comprising: forming an electrode slurry layer on the current collector sheet by branching and discharging electrode slurry stored in a lower manifold located in the lower block into n rows by electrode slurry discharge lines formed in the lower pad; and forming an insulating layer on the current collector sheet by branching and discharging insulating solution stored in an upper manifold located in the upper block into 2n rows by insulating solution discharge lines formed in the upper pad, the upper pad being located between the upper block and the middle block, and n being an integer of 1 or greater. For example, n is an integer in the range of 1 to 10, or from 1 to 5.

[0023] In one specific embodiment, the coating method according to the invention includes applying an electrode paste layer and an insulating layer formed on a current collector sheet to overlap each other, and the overlap range can be performed within the range of 5% to 30% of the width of the insulating layer formed in the vertical direction of the current collector sheet. The overlap range means that the area where the electrode paste layer and the insulating solution layer overlap in the width direction is based on a ratio of 100% of the length of the insulating layer in the width direction.

[0024] In another specific example, in the coating method according to the invention, the temperature (T1) of the insulating solution discharged by the insulating solution discharge line can be in the range of 22°C to 27°C, and the temperature (T2) of the slurry discharged by the electrode slurry discharge line can be in the range of 20°C to 25°C. The temperature (T1) of the insulating solution can be higher than the temperature (T2) of the electrode slurry, and the difference (T1-T2) between the temperature (T1) of the insulating solution and the temperature (T2) of the electrode slurry can be in the range of 1°C to 4°C.

[0025] In another example, the coating method according to the invention may further include drying the electrode paste applied to the current collector sheet after forming the insulating layer.

[0026] In another example, the coating method according to the invention may further include a step of mixing a UV polymerization initiator with the insulating solution prior to the step of forming the insulating layer.

[0027] For example, the UV polymerization initiator is one or more of the following: 2-hydroxy-2-methylphenylacetone (HMPP), 1-hydroxy-cyclohexylphenyl-ketone, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl oxy-phenyl-acetic acid, 2-[2-hydroxyethoxy]-ethyl oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[ [4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl]titanium, 4-isobutylphenyl-4′-methylphenyliodonium, hexafluorophosphate, and methylbenzoylcarbamate.

[0028] In another example, the method further includes the step of curing the insulating solution containing the UV polymerization initiator by irradiating the insulating solution containing the UV polymerization initiator applied to the current collector sheet with UV light after the insulating layer is formed.

[0029] Beneficial effects

[0030] This invention relates to a double-slit mold and a coating method using the double-slit mold, which has the following advantages: by simultaneously applying electrode paste and insulating solution using the double-slit mold, electrode paste slippage at the edges of the electrode paste layer is prevented; and by including a shim having a structure that forms multiple discharge lines capable of discharging electrode paste or insulating solution in multiple lines, the electrode paste layer and the insulating layer can be formed on the current collector sheet in a multi-line manner, thereby improving process efficiency. Attached Figure Description

[0031] Figure 1 It is a schematic diagram illustrating the formation of electrode paste layer and insulating layer on current collector plate in a conventional manner using separate electrode paste coating slit molds and separate insulating solution coating slit molds.

[0032] Figure 2 This is a schematic diagram illustrating a double-slit mold according to an embodiment of the present invention.

[0033] Figure 3 It is a drawing through a double-slit mold (which is) Figure 2 (A magnified representation of region "A") is a schematic diagram showing the formation of an electrode paste layer and an insulating layer on the current collector sheet.

[0034] Figure 4 This is a schematic diagram illustrating the electrode slurry discharge section and the insulating solution discharge section located at the front end of the double-slit mold according to a specific embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram illustrating the electrode slurry discharge section and the insulating solution discharge section located at the front end of the double-slit mold according to another specific embodiment of the present invention.

[0036] Figure 6 This is an exploded perspective view of a double-slit mold according to another embodiment of the present invention.

[0037] Figure 7 It is used for drawing. Figure 6 A schematic diagram showing the formation of an electrode paste layer and an insulating layer on a current collector plate using a double-slit mold.

[0038] Figure 8 This is an exploded perspective view illustrating a double-slit mold according to another embodiment of the present invention.

[0039] Figure 9 It is used for drawing. Figure 8 A schematic diagram showing the formation of an electrode paste layer and an insulating layer on a current collector plate using a double-slit mold.

[0040] Figure 10 This is an exploded perspective view of a double-slit mold including a UV lamp according to another embodiment of the present invention.

[0041] Figure 11 It is used for drawing. Figure 10 A schematic diagram showing the formation of an electrode paste layer and an insulating layer on a current collector plate using a double-slit mold. Detailed Implementation

[0042] The present invention will now be described in detail. Prior to this, the terms or expressions used in the specification and claims should not be construed as limited to their conventional or dictionary meanings, but rather should be interpreted as having meanings and concepts consistent with the technical concept of the present invention, based on the principle that the inventor may appropriately define the concepts of the terms in order to best illustrate his / her own invention.

[0043] The present invention provides a double-slit mold. In one embodiment, the double-slit mold according to the present invention includes a gasket having multiple electrode slurry discharge lines and a gasket having multiple insulating solution discharge lines, the gaskets being capable of forming multiple rows of electrode slurry layers and insulating layers on a current collector sheet.

[0044] The present invention is characterized by simultaneously coating the current collector sheet with electrode paste and insulating solution by discharging electrode paste and insulating solution from one slit mold via a double-slit mold. By rapidly applying the insulating solution to the edge of the electrode paste layer via the double-slit mold, an insulating layer is formed before the electrode paste slippage occurs at the boundary of the electrode paste layer applied to the current collector sheet, preventing undesirable electrode paste slippage and improving quality. It also prevents breakage and camber of the current collector sheet caused by the separate positioning of the electrode paste coating slit mold and the insulating solution coating slit mold in the conventional method. Furthermore, in this invention, by including a shim with multiple electrode paste discharge lines and a shim with multiple insulating solution discharge lines in the double-slit mold, a multi-line coating of electrode paste and insulating solution is formed on a single current collector sheet, thereby improving production efficiency.

[0045] In one embodiment, the double-slit mold according to the present invention includes a lower block, a middle block, and an upper block. The double-slit mold includes a lower gasket located between the lower block and the middle block, an upper gasket located between the middle block and the upper block, a lower manifold formed in the lower block to store electrode paste, and an upper manifold formed in the upper block to store insulating solution.

[0046] Furthermore, the double-slit mold has the following structure: the electrode paste stored in the lower manifold is branched and discharged in n rows by the electrode paste discharge line formed in the lower gasket, and the insulating solution stored in the upper manifold is branched and discharged in 2n rows by the insulating solution discharge line formed in the upper gasket, where n is an integer of 1 or greater. For example, n is an integer ranging from 1 to 10 or from 1 to 5.

[0047] The lower block, middle block, and upper block can be one of the conventional forms. In addition, the upper manifold and lower manifold can also be one of the conventional forms.

[0048] The lower gasket located between the lower block and the middle block includes discharge lines for discharging electrode slurry stored in the lower manifold, and in this case, multiple discharge lines can be formed. Simultaneously, the upper gasket located between the middle block and the upper block includes discharge lines for discharging insulating solution stored in the upper manifold, and in this case, multiple discharge lines can also be formed. Since the insulating layer should be formed on the left and right edges of the electrode slurry layer formed on the current collector sheet, the number of discharge lines for discharging the insulating solution can be twice the number of discharge lines for discharging the electrode slurry. Accordingly, the double-slit mold has the following structure: the electrode slurry stored in the lower manifold is branched and discharged in n rows by the electrode slurry discharge lines formed in the lower gasket, and the insulating solution stored in the upper manifold is branched and discharged in 2n rows by the insulating solution discharge lines formed in the upper gasket, where n is an integer of 1 or greater.

[0049] Specifically, the lower gasket may have a structure having an electrode slurry discharge line for discharging electrode slurry stored in the lower manifold in a direction perpendicular to the cross-section of the lower gasket, and an electrode slurry discharge portion serving as an opening of the electrode slurry discharge line. Simultaneously, the upper gasket may have a structure having an insulating solution discharge line for discharging insulating solution stored in the upper manifold in a direction perpendicular to the cross-section of the upper gasket, and an insulating solution discharge portion serving as an opening of the insulating solution discharge line. Furthermore, the upper and lower gaskets may each have a structure in which all sides are closed except for the electrode slurry discharge portion and the insulating solution discharge portion. In this case, the electrode slurry discharge line may have a shape that narrows towards the electrode slurry discharge portion. This allows for receiving electrode slurry supplied from the lower manifold within a wider width, and for fine adjustment of the electrode slurry discharged through the electrode slurry discharge portion, the width of the electrode slurry discharge line may be formed narrower near the electrode slurry discharge portion. In this case, the width of the insulating solution discharge line can be narrower when the insulating solution discharge line is also close to the insulating solution discharge section.

[0050] In one embodiment, the angle at which the first plane extending from the upper gasket intersects the second plane extending from the lower gasket forms an angle ranging from 20° to 60°. Specifically, the angle at which the first plane extending from the upper gasket intersects the second plane extending from the lower gasket can be in the range of 20° to 45°, 20° to 35°, 25° to 50°, or 25° to 40°. This corresponds to the forming angle of the front end of the intermediate block in the vertical direction on the side of the double-slit mold. When the upper and lower gaskets extend based on this cross-section, they can intersect each other at one location, and the insulating solution discharge portion and the electrode slurry discharge portion can be adjacent to each other near the intersection point. Accordingly, the discharge points of the electrode slurry and the insulating solution can be concentrated at approximately one location. When the intersection angle between the extended planes of the upper and lower gaskets is less than 20°, the flow of the electrode slurry discharged through the electrode slurry discharge section of the lower gasket collides with the surface of the current collector, causing the flow of the electrode slurry to suddenly become stronger in the direction opposite to the rotation direction of the coating roller, which may cause leakage. On the other hand, when the intersection angle between the extended planes of the upper and lower gaskets exceeds 60°, the flow of the electrode slurry discharged through the electrode slurry discharge line becomes difficult, and higher pressure may be required to achieve smooth flow.

[0051] In this invention, the first plane extending from the upper gasket corresponds to the insulating solution discharge line through which the insulating solution is discharged. Furthermore, the second plane extending from the lower gasket corresponds to the electrode slurry discharge line through which the electrode slurry is discharged.

[0052] In this invention, the first plane extending from the upper gasket can form an angle approximately perpendicular to the current collector plate, through which the insulating solution is discharged. For example, the first plane extending from the upper gasket forms an angle with the current collector plate in the range of 75° to 115°, 80° to 100°, or 85° to 95°. Furthermore, the second plane extending from the lower gasket forms a constant tilt angle with the current collector plate, through which the electrode slurry is discharged. In this invention, the electrode slurry is discharged at an angle relative to the current collector plate, and the insulating solution is discharged perpendicular to the current collector plate. Therefore, this invention can improve the uniformity of the insulating solution coating while stably discharging the electrode slurry onto the current collector plate.

[0053] In another specific embodiment, the double slit mold according to the present invention may have the following structure: the width of the electrode slurry discharge portion (which is the opening portion of the electrode slurry discharge line) and the width of the insulating solution discharge portion (which is the opening portion of the insulating solution discharge line) do not overlap with each other in the vertical direction of the cross section of the upper gasket.

[0054] With this structure, the electrode paste layer can slide naturally due to gravity, allowing the gap between the electrode paste layer and the insulating layer formed on the current collector sheet immediately after the electrode paste and insulating solution coating process to be filled by the sliding electrode paste. Even if gaps still exist, the electrode paste layer and the insulating layer will be compressed by rolling during the rolling process after the coating process, allowing the electrode paste layer and the insulating layer to overlap to fill the gaps, thereby forming a uniform electrode paste layer and insulating layer. Simultaneously, considering both the sliding phenomenon of the electrode paste and the rolling process, it is preferable to set an appropriate distance so that the width of the electrode paste discharge portion and the width of the insulating solution discharge portion do not overlap.

[0055] In another specific embodiment, the double-slit mold according to the invention may have the following structure: the width of the electrode slurry discharge portion (which is the opening portion of the electrode slurry discharge line) and the width of the insulating solution discharge portion (which is the opening portion of the insulating solution discharge line) overlap each other in the vertical direction of the cross-section of the upper gasket, and the overlap range is 5% to 30% of the width of the insulating layer formed in the vertical direction on the current collector sheet. Specifically, the overlap range is in the range of 5% to 20%, 10% to 30%, or 5% to 10% of the width of the insulating solution discharge portion. In order to prevent the electrode slurry layer formed on the current collector sheet from contacting the insulating layer, this structure has a structure in which the width of the electrode slurry discharge portion and the width of the insulating solution discharge portion overlap at a certain interval, such that the electrode slurry layer and the insulating layer fully overlap, and thus prevents gaps from appearing between the insulating layer and the electrode slurry layer of the current collector sheet. At this point, if the overlap range is too small compared to the width of the insulating solution discharge section, the insulating layer may not overlap sufficiently with the electrode slurry layer. If it is too large, there may be a problem that the degree of overlap between the insulating layer and the electrode slurry layer is too wide, and the coating thickness in the overlapping area is too thick, and the overall thickness of the electrode slurry layer and the insulating layer becomes uneven.

[0056] In another specific embodiment, the thickness of the coated insulating layer can be 5% to 50% of the thickness of the electrode slurry layer, for example, 1 μm to 100 μm. Meanwhile, the thickness of the positive electrode slurry layer can be 30 μm to 400 μm, preferably 50 μm to 110 μm. Within this thickness range of the insulating layer, the thickness of the lithium secondary battery can be reduced by forming an insulating layer with appropriate strength. On the other hand, when the coating thickness of the insulating layer is too thin, it may be difficult to obtain the desired electrical insulation, while when the coating thickness of the insulating layer is too thick, there are problems with longer coating solidification time or increased thickness.

[0057] Meanwhile, the width and length of the insulation layer can be from 1mm to 10mm, but can be changed depending on the purpose, and therefore need not be limited to this.

[0058] Meanwhile, the insulating layer can be a porous polymer film comprising multiple pores. This prevents short circuits between the positive and negative electrodes while allowing the electrolyte to pass through, thus providing a pathway through which lithium ions included in the lithium secondary battery can actively move. Accordingly, the insulating layer can be used as a separator included in a typical lithium secondary battery.

[0059] In another embodiment, the electrode slurry discharge section (which is the opening portion of the electrode slurry discharge line) is located upstream in the direction in which the electrode slurry and insulating solution are applied to the current collector plate, while the insulating solution discharge section (which is the opening portion of the insulating solution discharge line) is located downstream, and may further include a UV lamp located downstream of the insulating solution discharge section. This means that the upstream electrode slurry discharge section is positioned closer to the ground than the insulating solution discharge section, and the insulating solution discharge section is positioned closer to the ground than the UV lamp.

[0060] A UV lamp is a device that emits a UV (extreme ultraviolet) light source, which induces photocuring through a UV photoinitiator. This is achieved by adding the aforementioned UV polymerization initiator to an insulating solution and then immediately irradiating the insulating solution containing the extreme ultraviolet polymerization initiator with UV light after the current collector sheet is applied, thus rapidly curing the insulating solution containing the UV polymerization initiator. The insulating solution containing the cured UV polymerization initiator acts as a wall or barricade on the exterior of the electrode paste layer, rapidly preventing slippage of the electrode paste layer and thereby improving the uniformity of the coating formed on the current collector sheet. Furthermore, the UV lamp can be any type of conventional UV lamp suitable for selection by those skilled in the art, and its form is not particularly limited.

[0061] In addition to UV lamps, lamps capable of radiating other light sources (such as X-rays and electron beams) or heating devices that radiate heat can be used. Lamps capable of radiating other light sources (such as X-rays and electron beams) can cure insulating solutions containing light-source polymerization initiators, and heating devices can cure insulating solutions containing thermal polymerization initiators by supplying heat to the insulating solution. Lamps capable of radiating other light sources (such as X-rays and electron beams) and heating devices can be any of the conventional devices and are not particularly limited thereto.

[0062] Furthermore, the present invention provides a coating method using the double-slit mold described above. It may include elements common to the double-slit mold described above, and some of these common elements may be omitted.

[0063] In one embodiment, the coating method according to the present invention using a double-slit mold is a coating method for applying electrode slurry and insulating solution to a current collector sheet by means of a double-slit mold comprising a lower block, a middle block, and an upper block. The method includes: forming an electrode slurry layer on the current collector sheet by branching and discharging electrode slurry stored in a lower manifold located in the lower block into n rows by electrode slurry discharge lines formed in the lower pad; and forming an insulating layer on the current collector sheet by branching and discharging insulating solution stored in an upper manifold located in the upper block into 2n rows by insulating solution discharge lines formed in the upper pad, the upper pad being located between the upper block and the middle block, and n being an integer of 1 or greater. Specifically, n is an integer ranging from 1 to 10, or an integer ranging from 1 to 5.

[0064] As described above, the present invention can form rows in which electrode paste stored in a lower manifold is discharged into n branched rows of electrode paste via n electrode paste discharge lines of the lower gasket, thereby forming n electrode paste layers on the current collector sheet. Similarly, insulating solution stored in an upper manifold can form rows to form 2n insulating layers on the current collector sheet by discharging 2n branched rows of insulating solution via 2n insulating solution discharge lines of the upper gasket. That is, the electrode paste stored in a lower manifold branches into several branches of the lower gasket, and the electrode paste layers can be formed into several rows of electrode paste on the current collector sheet via these discharge lines. At the same time, the insulating solution stored in an upper manifold can be formed into several rows of insulating solution insulating layers on the current collector sheet via the branched discharge lines of the upper gasket, thereby improving manufacturing efficiency.

[0065] Furthermore, as described above, the double-slit mold of the present invention has a structure including a lower pad located between the lower block and the middle block and an upper pad located between the middle block and the upper block, and this structure can prevent the electrode paste from sliding by simultaneously applying an insulating solution to the current collector sheet via an electrode paste discharge line formed in the lower pad and an insulating solution discharge line provided in the upper pad.

[0066] In one specific embodiment, the coating method using a double-slit mold according to the present invention includes applying an electrode paste layer and an insulating layer formed on a current collector sheet to overlap each other, and the overlap range can be coated within the range of 5% to 30% of the width of the insulating layer formed in the vertical direction of the current collector sheet. Specifically, the overlap range is within the range of 5% to 20%, 10% to 30%, or 5% to 10% of the width of the insulating solution discharge portion.

[0067] This allows for sufficient overlap of the insulating layer on the electrode paste layer, preventing gaps between the insulating layer and the electrode paste layer in the current collector plate. However, if the overlap is too small relative to the width of the insulating layer, the insulating layer may not overlap sufficiently with the electrode paste layer; conversely, if the overlap is too large, the overlap may be too wide, resulting in a thicker coating in the overlapping area and uneven overall thickness of the electrode paste layer and the insulating layer.

[0068] In another specific embodiment, in the coating method using the double-slit mold according to the invention, the temperature (T1) of the insulating solution discharged from the insulating solution discharge line can be in the range of 22°C to 27°C, and the temperature (T2) of the slurry discharged from the electrode slurry discharge line can be in the range of 20°C to 25°C. The temperature (T1) of the insulating solution can be higher than the temperature (T2) of the electrode slurry, and the difference (T1-T2) between the temperature (T1) of the insulating solution and the temperature (T2) of the electrode slurry can be in the range of 1°C to 4°C.

[0069] Electrode paste typically has lower viscosity than insulating solution, causing it to slide downwards at the edges of the electrode paste layer after being coated onto the current collector plate. Conversely, because the insulating solution has higher viscosity than the electrode paste, less sliding occurs at the edges of the insulating layer after being coated onto the current collector plate compared to the electrode paste layer. Simultaneously, the higher viscosity of the insulating solution reduces its fluidity through the insulating solution discharge line. Therefore, the temperature of the insulating solution (T1) is higher than the temperature of the electrode paste (T2), thereby increasing the fluidity of the insulating solution and preventing electrode paste layer sliding. At this point, the temperature (T1) of the insulating solution discharged from the insulating solution discharge line is in the range of 22°C to 27°C, and the temperature (T2) of the paste discharged from the electrode paste discharge line is in the range of 20°C to 25°C, and the temperature difference (T, -T2) between the insulating solution temperature (T1) and the electrode paste temperature (T2) can be controlled within the range of 1°C to 4°C. The temperatures (T1) of the insulating solution and (T2) of the electrode slurry are typically those used in the coating process, but can be appropriately varied according to the ambient temperature, and therefore need not be limited to these temperatures. However, as described above, it is desirable to control the temperature difference (T1-T2) between the insulating solution (T1) and the electrode slurry (T2) within the range of 1°C to 4°C to control the flowability of the insulating solution and the electrode slurry, thereby generating optimal coating conditions. Simultaneously, when the temperature difference (T1-T2) between the insulating solution (T1) and the electrode slurry (T2) is less than 1°C, the desired control of the flowability of the electrode slurry and the insulating solution may not be achieved. On the other hand, when the temperature exceeds 4°C, the flowability of the insulating solution increases excessively, which may cause slippage of the insulating layer, and the flowability of the electrode slurry may decrease, making it impossible to form a uniform electrode slurry layer.

[0070] In another example, the coating method using a double-slit mold according to the present invention may further include drying the electrode paste applied to the current collector sheet after forming the insulating layer. In this case, as a drying method, moisture can be removed by completely drying the electrode paste using drying methods known in the art. Drying can be carried out by changing the hot air method, direct heating method, conductive heating method, etc., at a temperature at which all moisture evaporates, but is not limited thereto.

[0071] In another example, the coating method using a double-slit mold according to the invention may further include a step of mixing a UV polymerization initiator with an insulating solution prior to the step of forming the insulating layer. This can be achieved by irradiating the insulating layer containing the UV polymerization initiator with UV light, as will be described later.

[0072] Specifically, the UV polymerization initiator may include one or more of the following: 2-hydroxy-2-methylphenylacetone (HMPP), 1-hydroxy-cyclohexylphenyl-one, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl oxy-phenyl-acetic acid, 2-[2-hydroxyethoxy]-ethyl oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl- 1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl]titanium, 4-isobutylphenyl-4′-methylphenyliodonium, hexafluorophosphate, and methylbenzoylcarbamate, and in addition to the UV polymerization initiators described above, may also include conventional UV polymerization initiators readily available to those skilled in the art.

[0073] In another example, the coating method using a double-slit mold according to the invention may further include curing the insulating solution containing a UV polymerization initiator by irradiating the insulating solution applied to the current collector sheet with UV light after forming the insulating layer.

[0074] In this case, the insulating solution containing a UV polymerization initiator can be a UV-curable material. Specifically, the UV-curable material can include an insulating polymer resin as a UV-curable polymer. In this invention, where curing of the insulating polymer resin to form an insulating layer is required, resins with shorter curing times and simpler curing methods are preferred. Therefore, one or more of UV-curable silicone resins, UV-curable acrylic resins, UV-curable epoxy resins, and UV-curable polyurethane resins can be used, which can be easily cured simply by irradiation with UV light. UV-curable polyurethane resins can include polyurethane acrylates, and UV-curable epoxy resins can include epoxy acrylates.

[0075] As described above, an insulating solution containing a UV polymerization initiator is applied to the current collector sheet, and the insulating layer containing the UV polymerization initiator is rapidly cured by irradiation with UV light. The insulating layer containing the cured UV polymerization initiator is stronger than the uncured insulating layer, and therefore can also serve as a guiding layer in the subsequent rolling process to prevent it from being pushed by the electrode paste layer. In addition, the slippage of the electrode paste layer can be minimized by rapidly curing the insulating layer containing the UV polymerization initiator.

[0076] In addition to UV polymerization initiators, light source polymerization initiators that initiate polymerization via other light sources besides UV light (such as X-rays and electron beams) can be included. Furthermore, thermal polymerization initiators can be used to initiate polymerization by supplying heat. Preferably, an insulating solution containing a curable resin that can be cured by heat or a light source (such as X-rays or electron beams) is used. In this case, the curable resin cured by a light source such as X-rays or electron beams is preferably one or more of silicone resins, acrylic resins, epoxy resins, and polyurethane resins that are cured by a light source such as X-rays or electron beams or by heat. Furthermore, as a heat-curable resin, one or more selected from modified polypropylene, polypropylene-butadiene-ethylene terpolymers, acrylic resins, and silicone resins can be used, and the modified polypropylene can be cast polypropylene (CPP).

[0077] In another example, the coating method using a double-slit mold according to the invention may further include the step of forming a stability-enhancing layer on the insulating layer after forming the insulating layer. This stability-enhancing layer is a mixture comprising inorganic oxides and is formed on the insulating layer to improve the mechanical strength of the insulating layer and also to enhance its resistance to thermal shrinkage.

[0078] The inorganic oxide may be one or more selected from the group consisting of: Al2O3, BaTiO3, CaO, CeO2, NiO, MgO, SiO2, SnO2, SrTiO3, TiO2, Y2O3, ZnO, ZrO2, Pb(Zr,Ti)O3(PZT), (Pb,La)(Zr,Ti)O3(PLZT), PB(Mg3Nb 2 / 3 The substances are O3-PbTiO3 (PMN-PT) and hafnium dioxide (HfO2), and specifically may be one or more selected from the group consisting of Al2O3, SiO2, Y2O3 and ZrO2.

[0079] In this case, the inorganic oxide can be particulate, and the average particle size can be from 1 nm to 10 μm, specifically from 0.01 μm to 7 μm, and more specifically from 0.1 μm to 5 μm. When the average particle size of the inorganic oxide is 1 nm or larger, it can exhibit suitable dispersibility to prevent the inorganic oxide from interfering with the movement of lithium ions, and when it is 10 μm or smaller, the thickness of the entire electrode can be kept within an appropriate range by preventing the stability enhancement layer from becoming too thick.

[0080] The mixture comprising inorganic oxides may further comprise an adhesive material, and the inorganic oxides and adhesive material may be mixed in a weight ratio of 99:1 to 80:20, specifically 95:5 to 90:10. By including the adhesive material in the mixture comprising inorganic oxides, the inorganic oxides can be firmly bonded to the insulating layer.

[0081] The adhesive material may be one or more selected from the group consisting of: polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polyvinylidene fluoride-trichlorofluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl amylopectin, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, amylopectin, carboxymethyl cellulose, acrylonitrile styrene-butadiene copolymer, polyimide, and styrene-butadiene rubber (SBR).

[0082] The stability enhancement layer can have a thickness of 0.1 μm to 30 μm, specifically, a thickness of 1 μm to 20 μm, and more specifically, a thickness of 2 μm to 10 μm. When the thickness of the stability enhancement layer is 0.1 μm or greater, the stability enhancement layer exhibits an appropriate level of strength while improving the mechanical strength of the insulation layer and enhancing its resistance to thermal shrinkage. When the thickness of the stability enhancement layer is 30 μm or less, the total thickness of the electrode can be reduced, thereby achieving a reduction in the thickness of the lithium secondary battery including the electrode.

[0083] Meanwhile, the insulating material, as the main component of the insulating solution, may include any one or a mixture of two or more of the group consisting of butyl acrylate, styrene, acrylic acid, ethyl hydrogen acrylate, and styrene-butadiene rubber (SBR). The insulating material may be an aqueous solution dispersed in water in an amount of 10% to 90% by weight.

[0084] Furthermore, the polymeric material contained in the insulating solution may be one or more selected from the group consisting of: polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as aromatic polyamides, polyaldehyde resins, polycarbonates, polyimides, polyetheretherketones, polyethersulfones, polyphenylene ethers, polyphenylene sulfides, polyvinyl naphthalene, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyacrylonitrile, cellulose, nylon, poly(p-phenylenebenzobisoxazole), and polyarylates. Specifically, it may be a polyolefin, and more specifically, it may be one or more selected from the group consisting of polyethylene, polypropylene, polybutene, and polystyrene.

[0085] The polymer mixture may further include an adhesive material, and the polymer and adhesive material may be mixed in a weight ratio of 99:1 to 80:20, specifically 95:5 to 90:10. By including the adhesive material in the polymer mixture, the polymer can be more firmly bonded to the active material layer.

[0086] The adhesive material may be one or more selected from the group consisting of: polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polyvinylidene fluoride-trichlorofluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl amylopectin, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, amylopectin, carboxymethyl cellulose, acrylonitrile styrene-butadiene copolymer, polyimide, and styrene-butadiene rubber (SBR).

[0087] Meanwhile, electrode slurry refers to a composition including electrode active materials in a slurry state. Current collector sheet refers to positive electrode current collector sheet, where positive electrode refers to the positive electrode used in secondary batteries, and specifically to the positive electrode used in lithium secondary batteries.

[0088] The positive electrode has a structure in which a two-layer positive electrode active material layer is stacked on a positive electrode current collector. In one example, the positive electrode active material layer includes a positive electrode active material, a conductive material, a binder polymer, and the like, and may further include, when necessary, positive electrode additives commonly used in the art.

[0089] The positive electrode active material can be a lithium-containing oxide, and can be the same or different. Lithium-containing transition metal oxides can be used as lithium-containing oxides.

[0090] For example, lithium-containing transition metal oxides can be any one of the following groups of materials, or a mixture of two or more of them: Li x CoO2 (0.5 < x < 1.3), Li x NiO2 (0.5 < x < 1.3), Li x MnO2 (0.5 < x < 1.3), Li x Mn₂O₄ (0.5 < x < 1.3), Li x (Ni a Co b Mnc)O2 (0.5<x<1.3, 0<a<1, 0<b<1, 0<c<1, a+b+c=1), Li x Ni 1-y Co y O2(0.5<x<1.3, 0<y<1), Lix Co 1-y MnyO2(0.5<x<1.3, 0<y<1), LixNi 1-y Mn y O2(0.5<x<1.3, 0<y<1), Li x (Ni a Co b Mn c )O4(0.5<x<1.3, 0<a<2, 0<b<2, 0<c<2, a+b+c=2), Li x Mn 2-z Ni z O4(0.5<x<1.3, 0<z<2), Li x Mn 2-z Co z O4(0.5<x<1.3, 0<z<2), Li x CoPO4 (0.5 < x < 1.3) and Li x FePO4 (0.5 < x < 1.3). In addition, lithium-containing transition metal oxides can be coated with metals or metal oxides such as aluminum (Al). Furthermore, besides lithium-containing transition metal oxides, one or more of sulfides, selenides, and halides can be used.

[0091] The positive electrode active material layer may include 94.0 to 98.5% by weight of positive electrode active material. When the content of the positive electrode active material meets the above range, it is advantageous for manufacturing high-capacity batteries and for providing sufficient positive electrode conductivity or adhesion between electrode materials.

[0092] The current collector for the positive electrode is a metal with high conductivity, and any metal that can easily adhere to the positive electrode active material slurry can be used, as long as it is not reactive within the voltage range of the electrochemical device. Specifically, non-limiting examples of the current collector for the positive electrode include foils made of aluminum, nickel, or combinations thereof. The positive electrode active material layer further includes a conductive material.

[0093] Carbon-based conductive materials are commonly used as conductive materials, and include sphere-type or needle-type carbon-based conductive materials. Spherical carbon-based conductive materials, when mixed with a binder, fill pores (the gaps between particles of the active material) to improve the physical contact between the active materials, thereby reducing interfacial resistance and increasing the adhesion between the lower positive electrode active material and the current collector.

[0094] Examples of spherical carbon-based conductive materials include carbon black, including Denka Black, and examples include FX35 (Denka Corporation), SB50L (Denka Corporation), and Super-P, but are not limited to these. Here, 'sphere type' means having a spherical particle shape and an average diameter (D50) of 10 to 500 nm, specifically 15 to 100 nm or 15 to 40 nm.

[0095] In contrast to spherical carbon-based conductive materials, there are needle-type carbon-based conductive materials. Spherical carbon-based conductive materials can be carbon nanotubes (CNTs), vapor-grown carbon fibers (VGCF), carbon nanofibers (CNFs), or mixtures of two or more of these. Here, 'needle-type' refers to the shape of the needle-like particles, such as an aspect ratio (length / diameter value) in the range of 50 to 650, specifically 60 to 300 or 100 to 300.

[0096] Spherical carbon-based conductive materials have the advantage of better dispersibility compared to needle-shaped conductive materials, and due to their lower conductivity compared to needle-shaped carbon-based conductive materials, they have the effect of improving the insulation properties of the corresponding layer.

[0097] The electrode typically contains 0.5 to 5% conductive material relative to the total weight of the positive electrode active material layer. When the content of conductive material meets the above range, it provides sufficient positive electrode conductivity and reduces the interfacial resistance between the current collector and the active material.

[0098] Adhesives commonly used in the art can be used as adhesive polymers without restriction. For example, when the adhesive is soluble in organic solvents but insoluble in water, water-insoluble polymers or water-soluble polymers that are insoluble in organic solvents but soluble in water can be used. Examples of water-insoluble polymers may be one or more selected from the group consisting of: polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), polypropylene oxide (PPO), ethylene oxide-propylene oxide copolymer (PEO-PPO), polytetrafluoroethylene (PTFE), polyimide (PI), polyetherimide (PEI), styrene-butadiene rubber (SBR), polyacrylates, and derivatives thereof.

[0099] The water-soluble polymer can be one or more selected from various cellulose derivatives, such as carboxymethyl cellulose (CMC), methyl cellulose (MC), cellulose acetate phthalate (CAP), hydroxypropyl methyl cellulose (HPMC), and hydroxypropyl methyl cellulose phthalate (HPMCP).

[0100] The content of the binder polymer is proportional to the content of conductive material included in the upper and lower positive electrode active material layers. This is because, in order to provide adhesion to the conductive material, which has a relatively small particle size compared to the active material, more binder polymer is required when the conductive material content increases, while less binder polymer can be used when the conductive material content decreases.

[0101] Detailed description of preferred embodiments

[0102] The invention will now be described in more detail with reference to the accompanying drawings. While the invention allows for various modifications and forms, specific embodiments are illustrated and described in detail herein. However, this is not intended to limit the invention to the specific embodiments, but should be understood to include all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0103] (First Implementation)

[0104] Figure 2 This is a schematic diagram illustrating a double-slit mold 200 according to an embodiment of the present invention; see also Figure 2 The double-slit mold 200 according to the present invention includes: a lower block 12, an intermediate block 11, and an upper block 10; a lower gasket 21 and a lower spacer 23 located between the lower block 12 and the intermediate block 11; and an upper gasket 20 and an upper spacer 22 located between the intermediate block 11 and the upper block 10. Furthermore, the double-slit mold 200 may have a structure including a lower manifold 14 and an upper manifold 13, wherein the lower manifold 14 is formed in the lower block 12 and stores electrode paste 30, and the upper manifold 13 is formed in the upper block 10 and stores insulating solution 31, wherein the electrode paste 30 stored in the lower manifold 14 is branched and discharged through an electrode paste discharge line 25 formed in the lower gasket 21, and the insulating solution 31 stored in the upper manifold 13 is branched and discharged through an insulating solution discharge line 27 formed in the upper gasket 20.

[0105] Figure 3 It is illustrated by a double-slit mold 200 (which is Figure 2 (A magnified representation of region "A") is a schematic diagram showing the formation of an electrode paste layer 32 and an insulating layer 33 on the current collector sheet 16.

[0106] See Figure 3Electrode paste 30, discharged through electrode paste discharge portion 26 formed in the lower pad 21, can be coated onto current collector plate 16, which moves along the rotation direction of coating roller 15. Immediately afterwards, insulating solution 31, discharged through insulating solution discharge portion 28 formed in the upper pad 20, can be applied onto current collector plate 16. As a result, electrode paste 30 and insulating solution 31 are coated simultaneously to prevent electrode paste 30 from slipping at the edge of electrode paste layer 32.

[0107] Furthermore, the angle θ formed by the upper pad 20 and the lower pad, that is, the angle at which the first plane extending from the upper pad 20 and the second plane extending from the lower pad 21 intersect, is approximately 25°. Here, the upper pad 20 forms an angle perpendicular to the current collector 16 moving on the coating roller 15, and the lower pad 21 forms a 65° angle with the current collector 16. By forming such an discharge angle, the present invention can uniformly coat the insulating solution 31 while stably forming the electrode slurry layer 32.

[0108] (Second Implementation)

[0109] Figure 4 This is a schematic diagram illustrating the electrode slurry discharge section 26 and the insulating solution discharge section 28 located at the front end of the double-slit mold 200 according to another specific embodiment of the present invention. See also Figure 4 The electrode slurry discharge portion 26 of the lower pad 21 located between the lower block 12 and the middle block 11 and the insulating solution discharge portion 28 of the upper pad 20 located between the middle block 11 and the upper block 10 do not overlap with each other.

[0110] In this configuration, when the electrode paste 30 and the insulating solution 31 are coated on the current collector sheet...

[0111] When the electrode paste layer 32 and the insulating layer 33 are applied, a gap may appear. However, since the electrode paste layer 32 can slide naturally due to gravity, the gap between the electrode paste layer 32 and the insulating layer 33 formed immediately after the electrode paste 30 and insulating solution 31 coating process naturally causes the edge of the electrode paste layer 32 to slide over time due to gravity, and this gap can be filled by the sliding electrode paste 30. Even when a gap still exists, the electrode paste layer 32 and the insulating layer 33 are compressed by rolling during the rolling process after the coating process so that the electrode paste layer 32 and the insulating layer 33 can overlap, so that the gap can be filled, thereby forming a uniform electrode paste layer 32 and insulating layer 33. Taking this into consideration, the width of the electrode paste discharge portion 26 and the width of the insulating solution discharge portion 28 can be set to not overlap each other and to a suitable distance (a).

[0112] (Third Implementation)

[0113] Figure 5 This is a schematic diagram illustrating the electrode slurry discharge section 26 and the insulating solution discharge section 28 located at the front end of the double-slit mold 200 according to another specific embodiment of the present invention. See also Figure 5 The electrode slurry discharge portion 26 of the lower pad 21 located between the lower block 12 and the middle block 11 and the insulating solution discharge portion 28 of the upper pad 20 located between the middle block 11 and the upper block 10 overlap each other, and the structure shows an overlap within a range of about 10% (b) of the width of the discharge portion.

[0114] With this structure, the electrode paste layer 32 and the insulating layer 33 formed on the current collector sheet 16 can be fully overlapped to prevent gaps from appearing between the insulating layer 33 and the electrode paste layer 32 of the current collector sheet 16.

[0115] (Fourth Implementation)

[0116] Figure 6 This is an exploded perspective view of a double-slit mold 200 according to another embodiment of the present invention. Figure 7 It is used for drawing. Figure 6 A schematic diagram showing the state in which the double-slit mold 200 forms the electrode paste layer 32 and the insulating layer 33 on the current collector plate 16.

[0117] See Figure 6 The double slit mold 200 includes a lower block 12, a middle block 11 and an upper block 10; and a lower pad 21 located between the lower block 12 and the middle block 11 and an upper pad 20 located between the middle block 11 and the upper block 10.

[0118] The lower gasket 21 has a structure including two electrode slurry discharge lines 25 and two electrode slurry discharge sections 26, and the upper gasket 20 has a structure including four insulating solution discharge lines 27 and four insulating solution discharge sections 28. Simultaneously, the electrode slurry discharge lines 25 and the insulating solution discharge lines 27 may have a shape in which the width and length of each discharge line decrease, respectively, in the direction toward the electrode slurry discharge section 26 and in the direction toward the insulating solution discharge section 28. This maximizes the receiving area of ​​the electrode slurry 30 flowing in from the lower manifold 14, and the electrode slurry 30 contained and flowing through the electrode slurry discharge lines 25 is discharged through the narrowed electrode slurry discharge sections 26, thereby forming an electrode slurry layer 32 with a fine width on the current collector sheet 16. The same applies to the insulating solution discharge lines 27.

[0119] See Figure 7Two rows of electrode paste 30 can be applied to the current collector sheet 16 by means of a lower pad 21 in which two electrode paste discharge lines 25 and two electrode paste discharge portions 26 are formed therein and an upper pad 20 in which four insulating solution discharge lines 27 and four insulating solution discharge portions 28 are formed therein. Insulating solution 31 is applied to the left and right edges of each electrode paste layer 32 to form a total of four rows of insulating layers 33.

[0120] In this structure, the electrode paste 30 stored in a lower manifold 14 and the insulating solution 31 stored in an upper manifold 13 are respectively branched into several branches and discharged through a lower gasket 21 and an upper gasket 20, each having multiple discharge lines, and then coated on the current collector sheet 16 in a multiline manner, thereby improving manufacturing efficiency.

[0121] (Fifth Implementation)

[0122] Figure 8 This is an exploded perspective view of a double-slit mold 200 according to another embodiment of the present invention. Figure 9 It is used for drawing. Figure 8 A schematic diagram showing the state in which the double-slit mold 200 forms the electrode paste layer 32 and the insulating layer 33 on the current collector plate 16.

[0123] See Figure 8 The lower gasket 21 has a structure including four electrode slurry discharge lines 25 and four electrode slurry discharge sections 26, and the upper gasket 20 has a structure including eight insulating solution discharge lines 27 and eight insulating solution discharge sections 28.

[0124] See Figure 9 By using a double-slit mold comprising a lower pad 21 in which four electrode slurry discharge lines 25 and four electrode slurry discharge portions 26 are formed, and an upper pad 20 in which eight insulating solution discharge lines 27 and eight insulating solution discharge portions 28 are formed, four rows of electrode slurry 30 can be applied to the current collector sheet 16, and insulating solution 31 can be applied to the left and right edges of each electrode slurry layer 32 to form a total of eight rows of insulating layers 33.

[0125] In this structure, the electrode paste 30 stored in a lower manifold 14 and the insulating solution 31 stored in an upper manifold 13 are respectively branched into several branches and discharged through lower gaskets 21 and upper gaskets 20, each having multiple discharge lines, and then coated on the current collector sheet 16 in a multi-line manner, thereby improving manufacturing efficiency.

[0126] (Sixth Implementation Method)

[0127] Figure 10This is an exploded perspective view of a double-slit mold 200 including a UV lamp 40 according to another embodiment of the present invention. Figure 11 It is used for drawing. Figure 10 A schematic diagram showing the state in which the double-slit mold 200 forms an electrode paste layer and an insulating layer on the current collector plate 16.

[0128] See Figure 10 The structure includes Figure 6 The double-slit mold 200 includes all its components, and further includes a UV lamp 40 on the upper block 10. At this time, when the UV polymerization initiator is added to the insulating solution 31 and introduced into the upper manifold 13, after the insulating solution containing the UV polymerization initiator is applied to the current collector plate 16 through the insulating solution discharge line 27 of the upper gasket 20, UV light emitted from the UV lamp 40 is irradiated onto the insulating layer 34 containing the UV polymerization initiator, so that the insulating layer 34 containing the UV polymerization initiator can be cured to form an insulating layer 35 containing the finally cured UV polymerization initiator.

[0129] An insulating solution containing a UV polymerization initiator reacts with UV light to solidify the insulating solution. The solidified insulating solution hardens firmly within seconds to minutes, enabling rapid and effective prevention of slippage of the electrode paste 30 at the edges of the electrode paste layer. This results in the formation of an electrode paste layer with a uniform thickness.

[0130] [Explanation of reference numerals in the attached figures]

[0131] 10: Upper Block

[0132] 11: Intermediate Block

[0133] 12: Next Block

[0134] 13: Upper manifold

[0135] 14: Lower manifold

[0136] 15: Coating roller

[0137] 16: Current collector plate

[0138] 20: Upper gasket

[0139] 21: Lower gasket

[0140] 22: Upper spacer

[0141] 23: Lower spacer

[0142] 25: Electrode slurry discharge line

[0143] 26: Electrode slurry discharge section

[0144] 27: Insulating solution discharge line

[0145] 28: Insulation solution discharge section

[0146] 30: Electrode paste

[0147] 31: Insulating solution

[0148] 32: Electrode paste layer

[0149] 33: Insulation layer

[0150] 34: Insulating layer including UV polymerization initiator

[0151] 35: Insulating layer including cured UV polymerization initiator

[0152] 40: UV lamp

[0153] 100: Conventional electrode paste coating slot mold

[0154] 110: Conventional insulating solution coating slit mold

[0155] 200: Double Slit Mold

[0156] θ: Angle between the upper and lower shims

Claims

1. A double-slit mold, comprising a lower block, a middle block, and an upper block, wherein the double-slit mold includes: A lower pad located between the lower block and the middle block; An upper pad located between the middle block and the upper block; A lower manifold is formed in the lower block to store electrode paste; and An upper manifold is formed in the upper block to store an insulating solution. The double-slit mold has a structure in which the electrode paste stored in the lower manifold is branched and discharged into n rows by an electrode paste discharge line formed in the lower gasket, and the insulating solution stored in the upper manifold is branched and discharged into 2n rows by an insulating solution discharge line formed in the upper gasket. n is an integer of 1 or greater. The width of the electrode slurry discharge section and the width of the insulating solution discharge section overlap each other in the vertical direction of the cross-section of the upper gasket. The electrode slurry discharge section is the opening of the electrode slurry discharge line, and the insulating solution discharge section is the opening of the insulating solution discharge line. The overlap ranges from 5% to 30% of the width of the insulating solution discharge portion.

2. The double-slit mold as claimed in claim 1, wherein the angle between the first plane extending from the upper pad and the second plane extending from the lower pad is within the range of 20° to 60°.

3. The double-slit mold as claimed in claim 1, wherein in the direction in which the electrode slurry and the insulating solution are applied to the current collector plate, The electrode slurry discharge section is located upstream, and this section is the opening of the electrode slurry discharge line. The insulating solution discharge section is located downstream, and the insulating solution discharge section is the opening portion of the insulating solution discharge line. It further includes a UV lamp located downstream of the insulating solution discharge section.

4. A coating method for applying electrode paste and insulating solution to a current collector sheet using a double-slit mold, the double-slit mold comprising a lower block, a middle block, and an upper block, the method comprising: An electrode paste layer is formed on the current collector plate by branching and discharging the electrode paste stored in the lower manifold formed in the lower block into n rows through an electrode paste discharge line formed in the lower pad located between the lower block and the intermediate block; and An insulating layer is formed on the current collector sheet by branching and discharging the insulating solution stored in the upper manifold formed in the upper block into 2n rows through an insulating solution discharge line formed in the upper gasket located between the intermediate block and the upper block; n is an integer of 1 or greater. in The electrode paste layer and the insulating layer formed on the current collector sheet are applied to overlap each other, and The overlap range is 5% to 30% of the width of the insulating layer formed in the vertical direction of the current collector sheet.

5. The method of claim 4, wherein The temperature (T1) of the insulating solution discharged from the insulating solution discharge line is in the range of 22°C to 27°C, and The temperature (T2) of the electrode slurry discharged from the electrode slurry discharge line is in the range of 20°C to 25°C. in, The temperature (T1) of the insulating solution is higher than the temperature (T2) of the electrode slurry, and the difference (T1 - T2) between the temperature (T1) of the insulating solution and the temperature (T2) of the electrode slurry is in the range of 1°C to 4°C.

6. The method of claim 4, further comprising drying the electrode paste applied to the current collector sheet after forming the insulating layer.

7. The method of claim 4, further comprising mixing the UV polymerization initiator with the insulating solution prior to forming the insulating layer.

8. The method of claim 7, wherein the UV polymerization initiator is one or more of the following: 2-hydroxy-2-methylphenylacetone (HMPP), 1-hydroxy-cyclohexylphenyl-one, benzophenone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl oxy-phenyl-acetic acid, 2-[2-hydroxyethoxy]-ethyl oxy-phenyl-acetic acid, α-dimethoxy-α-phenylacetophenone, 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(η) 5-2,4-cyclopentadien-1-yl), bis[2,6-difluoro-3-(1H-pyrrolo-1-yl)phenyl]titanium, 4-isobutylphenyl-4'-methylphenyliodonium, hexafluorophosphate, and methylbenzoyl carboxylate.

9. The method of claim 7, further comprising, after forming the insulating layer, curing the insulating solution containing the UV polymerization initiator by irradiating the insulating solution containing the UV polymerization initiator applied to the current collector sheet with UV light.

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