Coating apparatus for separator and method of manufacturing separator using same

Abstract

The present disclosure provides a coating apparatus for a diaphragm, the coating apparatus comprising: a storage unit containing a coating liquid; a coating roller configured to transfer the coating liquid from the storage unit to at least one surface of the substrate conveyed in one direction; and a modular blade unit configured to remove a portion of the coating liquid on a surface of the coating roller, in which the modular blade unit includes at least one blade, and the coating roller rotates in the same direction as a conveying direction of the substrate.

Description

Technical Field

[0001] This disclosure relates to a coating apparatus and a method for manufacturing a separator for a lithium secondary battery using the coating apparatus.

[0002] This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2024-0067355, filed on May 23, 2024, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] In recent years, interest in energy storage technologies has been increasing. With applications expanding to power mobile phones, portable cameras, laptops, and electric vehicles, much effort has been put into the research and development of electrochemical devices. Among these, electrochemical devices are the most closely watched area, with the development of rechargeable secondary batteries becoming a focal point.

[0004] Secondary batteries are chemical batteries that can be used semi-permanently by continuously charging and discharging through electrochemical reactions. They are classified into lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium secondary batteries. Among these batteries, lithium secondary batteries dominate the secondary battery market due to their higher voltage and energy density compared to other types of batteries.

[0005] A lithium-ion secondary battery has a structure in which an electrode assembly comprising a positive electrode, a negative electrode, and a porous membrane interposed between the positive and negative electrodes is impregnated with an electrolyte. Each of the positive and negative electrodes comprises an active material coated on a current collector. In this case, the separator of the lithium-ion secondary battery is manufactured by applying a coating solution for forming a porous coating to a porous polymer substrate and drying the solvent.

[0006] Furthermore, methods for applying the coating liquid to a substrate, particularly a porous polymer substrate, can include, for example, dip coating, die coating, roll coating, or comma coating. In this case, roll coating refers to a method of transferring the coating liquid stored in a storage device to the substrate. In this case, a doctor blade can be used to control the coating liquid present on the coating roller. The coating roller can include grooves on its surface to transfer a larger amount of coating liquid to the substrate, and the number and depth of the grooves can be adjusted to control the amount of coating liquid transferred. However, to control the coating thickness, shape, or pattern, new coating rollers need to be manufactured, which increases the cost and time required to manufacture the diaphragm.

[0007] Furthermore, in order to meet the demand for diaphragms with various types of coatings, such as coatings with different patterns formed on a substrate or coating thickness adjusted along the length of the substrate, it is necessary to develop coating equipment for manufacturing such diaphragms. Summary of the Invention

[0008] Technical issues

[0009] This disclosure is designed to solve the aforementioned technical problems. Specifically, this disclosure aims to provide a coating apparatus that can change the coating thickness on a substrate or form a coating with multiple patterns without changing the coating roller.

[0010] Furthermore, this disclosure aims to provide a method for manufacturing a separator for a lithium secondary battery, in which the coating thickness on a substrate is varied or a coating with multiple patterns is formed.

[0011] Technical solution

[0012] To achieve the above objectives, according to one aspect of this disclosure, a coating apparatus according to the following embodiments and a method for manufacturing a separator for a lithium secondary battery using the coating apparatus are provided.

[0013] According to a first embodiment, a coating apparatus for a diaphragm is provided, comprising: a storage unit for containing a coating liquid; a coating roller configured to transfer the coating liquid from the storage unit to at least one surface of a substrate being conveyed in one direction; and a modular scraper unit configured to remove a portion of the coating liquid from the surface of the coating roller, wherein the modular scraper unit includes at least one scraper, and the coating roller has a plurality of grooves with an engraved pattern on the surface, and the coating roller rotates in the same direction as the conveying direction of the substrate.

[0014] According to the second embodiment, in the first embodiment, the scraper may have a protruding portion with an embossed pattern.

[0015] According to the third embodiment, in either the first or second embodiment, the modular scraper unit may include at least two scrapers.

[0016] According to the fourth embodiment, in the third embodiment, the modular scraper unit may further include a scraper rotating part that rotates the plurality of scrapers.

[0017] According to the fifth embodiment, in any one of the first to fourth embodiments, the modular scraper unit may include at least two scrapers, and the at least two scrapers may have protrusions with different embossed patterns.

[0018] According to the sixth embodiment, in any one of the first to fifth embodiments, the coating apparatus for the diaphragm may further include a position adjustment unit for adjusting the position of the modular scraper unit.

[0019] According to the seventh embodiment, in any one of the first to sixth embodiments, the modular scraper unit may be disposed between the conveying path of the substrate conveyed along the direction and the coating roller.

[0020] According to the eighth embodiment, in any of the first to seventh embodiments, the coating apparatus for the diaphragm may further include a slit mold for supplying a second coating liquid to the coating roller.

[0021] According to a ninth embodiment, a method for manufacturing a diaphragm is provided, the method comprising the step of applying a coating liquid to at least one surface of a substrate using a coating apparatus for a diaphragm according to any one of the first to eighth embodiments.

[0022] According to the tenth embodiment, in the ninth embodiment, the coating thickness, coating load, coating pattern, or two or more of these can be changed by adjusting the gap between the coating rollers and the doctor blades facing each other.

[0023] According to the eleventh embodiment, in any of the ninth or tenth embodiments, the step of applying the coating liquid may include changing the coating thickness, coating load, coating pattern, or two or more of these by replacing the blade of the modular blade unit.

[0024] According to the twelfth embodiment, in any of the ninth to eleventh embodiments, the step of applying the coating liquid may include varying the coating thickness, coating load, coating pattern, or two or more of these along the length direction of the substrate by adjusting the position of the modular scraper unit over time.

[0025] According to the thirteenth embodiment, in any of the ninth to twelfth embodiments, before the step of applying the coating liquid, the method may include measuring the properties of the coating liquid and adjusting the position of the modular scraper unit based on the measured properties of the coating liquid.

[0026] Beneficial effects

[0027] The coating apparatus for diaphragms according to embodiments of this disclosure can adjust the coating thickness, loading amount, or pattern of the coating on the substrate without changing the coating roller.

[0028] The coating apparatus for a diaphragm according to embodiments of this disclosure can adjust the coating thickness, loading amount, or pattern of the coating along the length of the substrate.

[0029] The coating apparatus for diaphragms according to embodiments of the present disclosure can form coatings with various patterns by using a coating roller having a plurality of grooves with an engraved pattern.

[0030] The coating apparatus for diaphragms according to embodiments of the present disclosure can form coatings of various shapes by applying different coating liquids to the grooved and non-grooved portions using a coating roller having a plurality of grooved portions with an engraved pattern.

[0031] The coating apparatus for diaphragms according to embodiments of the present disclosure makes it easy to quantitatively control the coating liquid and improves reproducibility and repeatability by using a coating roller with multiple grooves having an engraved pattern.

[0032] The method for manufacturing a diaphragm according to embodiments of this disclosure can adjust the coating thickness, loading amount, or pattern of the coating on the substrate without changing the coating roller.

[0033] The method for manufacturing a diaphragm according to embodiments of this disclosure allows for adjustment of the coating thickness, loading amount, or pattern along the length of the substrate. Attached Figure Description

[0034] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing description, are intended to provide a further understanding of the technical concept of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the matters described in the drawings.

[0035] Figure 1 This is a diagram schematically illustrating the structure of a coating apparatus for a diaphragm according to an embodiment of the present disclosure.

[0036] Figure 2 This is a schematic diagram illustrating the structure of a scraper according to an embodiment of the present disclosure.

[0037] Figure 3 This is a schematic diagram illustrating the structure of a scraper according to an embodiment of the present disclosure.

[0038] Figure 4 This is a diagram schematically illustrating the structure of a modular scraper unit according to an embodiment of the present disclosure.

[0039] Figure 5 This is a diagram schematically illustrating the structure of a scraper with different embossed patterns according to embodiments of the present disclosure.

[0040] Figure 6 This is a diagram schematically illustrating the structure of a coating apparatus for a diaphragm according to an embodiment of the present disclosure.

[0041] Figure 7This is a diagram schematically illustrating the structure of a coating apparatus for a diaphragm according to an embodiment of the present disclosure.

[0042] Figure 8 This is a diagram schematically illustrating the structure of a coating apparatus for a diaphragm according to an embodiment of the present disclosure.

[0043] Figure 9 The figure illustrates the removal of a portion of the coating liquid transferred to the coating roller by using a coating roller without grooves on its surface and a scraper with protrusions without embossed patterns.

[0044] Figure 10 This diagram illustrates the removal of a portion of the coating liquid transferred to the coating roller using a coating roller without grooves on its surface and a scraper with raised protrusions featuring embossed patterns.

[0045] Figure 11 This diagram illustrates the removal of a portion of the coating liquid transferred to the coating roller using a coating roller with grooves on its surface and a scraper with protrusions that do not have embossed patterns.

[0046] Figure 12 This diagram illustrates the removal of a portion of the coating liquid transferred to the coating roller using a coating roller with grooves on its surface and a scraper with raised patterns. Detailed Implementation

[0047] The terms or words used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but should be interpreted on the basis of meaning and concept corresponding to the technical concept of this disclosure, based on the principle that the inventor is allowed to appropriately define the terms for the purpose of best interpretation.

[0048] The terminology used herein is for describing exemplary implementations of this disclosure and is not intended to limit the scope of this disclosure. Unless the context clearly indicates otherwise, the singular forms include the plural forms.

[0049] <Definition>

[0050] Throughout the application, when a part "includes" a component, it means that other components are not excluded, but may be further included, unless otherwise stated.

[0051] In this application, "A and / or B" means "A or B or both".

[0052] Hereinafter, embodiments of the present disclosure will be described in full detail with reference to the accompanying drawings to enable those skilled in the art to readily implement the disclosure. However, the present disclosure may be embodied in many different forms and is not limited to the disclosed embodiments. In the drawings, irrelevant descriptions have been omitted for clarity, and similar reference numerals are used throughout the application for similar elements.

[0053] Coating equipment for diaphragms

[0054] This disclosure provides a coating apparatus for diaphragms.

[0055] Figure 1 This is a schematic diagram illustrating the structure of a coating apparatus 1 for a diaphragm according to an embodiment of the present disclosure.

[0056] Reference Figure 1 The coating apparatus 1 for the diaphragm includes: a storage unit 100 for containing coating liquid 20; a coating roller 200 for transferring coating liquid 20 from the storage unit 100 to at least one surface of a substrate 10 being conveyed in one direction; and a modular doctor blade unit 300 for removing a portion of the coating liquid 20 on the surface of the coating roller 200, wherein the modular doctor blade unit 300 includes at least one doctor blade 310, and the coating roller 200 has a plurality of grooves 201 with an engraved pattern on its surface and is configured to rotate in the same direction as the conveying direction of the substrate 10.

[0057] The coating apparatus 1 for a diaphragm according to an embodiment of the present disclosure includes a replaceable modular scraper unit 300 and a coating roller 200 having a plurality of grooves 201 with an engraved pattern.

[0058] Compared to using a single doctor blade, the coating apparatus 1 of this disclosure can form coatings with various patterns without changing the coating roller. Furthermore, since various patterns can be formed, high-precision coating and improved coating uniformity can be achieved.

[0059] Furthermore, compared to using a flat coating roller, the coating roller 200 of this disclosure has a groove portion 201 clearly defined from the non-grooved portion, which allows it to accommodate different coating liquids, thereby forming coatings of various shapes that are difficult to achieve with a flat coating roller. In addition, due to the presence of the groove portion, a constant loading of coating liquid can be achieved.

[0060] In other words, because the coating apparatus 1 of this disclosure has a groove 201, it can hold a larger amount of coating liquid compared to the absence of a groove 201, thereby improving reproducibility. Furthermore, since the coating apparatus 1 of this disclosure also has a modular doctor blade unit 300, the characteristics of the produced diaphragm can be changed simply by replacing the doctor blade.

[0061] In embodiments of this disclosure, the modular scraper unit 300 may further include a scraper rotating portion 320 for rotating a plurality of scrapers 310. The modular scraper unit 300 can cause the plurality of scrapers 310 to rotate around the scraper rotating portion 320.

[0062] In embodiments of this disclosure, the modular doctor blade unit 300 is not limited to a specific location and connection, and can have any location and connection for removing a portion of the coating liquid on the coating roller 200. For example, the modular doctor blade unit 300 can be connected to the outside of the storage unit 100, or it can be configured not to be directly connected to the storage unit 100.

[0063] The substrate 10 and coating liquid 20 in each figure are shown for reference only and are not intended to limit the coating equipment for diaphragms described in this disclosure.

[0064] Figure 2 This is a diagram schematically illustrating the structure of the scraper 310 according to an embodiment of the present disclosure.

[0065] In embodiments of this disclosure, the doctor blade 310 may have protrusions 311 with an embossed pattern. Specifically, the doctor blade 310 may have protrusions 311 with an embossed pattern on its edge that contacts the coating roller 200. The doctor blade 310 may have at least one protrusion 311 or at least two protrusions 311, depending on the desired embossed pattern. In this case, the protrusions 311 may be closer to the surface of the coating roller 200 than the non-protrusions, and as the coating roller 200 rotates, a larger amount of coating liquid in contact with the protrusions 311 can be removed. Therefore, a predetermined pattern can be formed in the coating.

[0066] Figure 3 This is a diagram schematically illustrating the structure of the scraper 310 according to an embodiment of the present disclosure.

[0067] In embodiments of this disclosure, the doctor blade 310 may have a convex shape at the edge that contacts the coating roller 200, i.e., it protrudes upwards so that the central portion of the doctor blade 310 is positioned close to the coating roller 200. When the doctor blade 310 has the above-described shape, and the coating roller 200 has a smooth surface, the coating can be formed such that it is thicker at both edges in the width direction of the substrate 10. For example, due to slippage in the electrode active material, the electrode may have a smaller height at both ends than at the center. In this case, when the doctor blade 310 has such a shape... Figure 3 When the shape is shown, the height difference can be compensated by increasing the coating thickness at both ends in the width direction.

[0068] Figure 4 This is a diagram schematically illustrating the structure of a modular scraper unit 300 according to an embodiment of the present disclosure.

[0069] In embodiments of this disclosure, the modular scraper unit 300 may detachably include at least one scraper 310, 310a, 310b. The modular scraper unit 300 may detachably include scrapers 310, 310a, 310b having various shapes, depending on the desired purpose.

[0070] In embodiments of this disclosure, the modular scraper unit 300 may include at least two scrapers 310, 310a, 310b. With two or more scrapers 310, 310a, 310b having different shapes, coatings with different surface patterns can be formed on at least one surface of the substrate 10 to which the coating liquid is transferred.

[0071] In embodiments of this disclosure, the modular scraper unit 300 may further include a scraper rotating portion 320 for rotating a plurality of scrapers 310, 310a, 310b. The modular scraper unit 300 can cause the plurality of scrapers 310, 310a, 310b to rotate around the scraper rotating portion 320.

[0072] Figure 5 This is a schematic diagram illustrating the structure of a scraper 310 with different embossed patterns according to embodiments of the present disclosure.

[0073] In embodiments of this disclosure, the modular scraper unit 300 may include at least two scrapers 310a and 310b, and the at least two scrapers 310a and 310b may have protrusions with different embossed patterns. For example, as Figure 5As shown, a first scraper 310a and a second scraper 310b with protrusions having different embossed patterns can form coatings with different surface patterns on at least one surface of the substrate 10 to which the coating liquid is transferred. Specifically, by having the first scraper 310a and the second scraper 310b, coatings with various surface patterns can be formed without changing the coating roller.

[0074] Figure 6 This is a schematic diagram illustrating the structure of a coating apparatus 1 for a diaphragm according to an embodiment of the present disclosure.

[0075] In embodiments of this disclosure, the coating apparatus 1 for the diaphragm may further include a position adjustment unit 400 for adjusting the position of the modular scraper unit 300. For example, the position adjustment unit 400 may be connected to the periphery of the storage unit 100 and configured to adjust the position of the modular scraper unit 300. The position adjustment unit 400 may adjust the position of the modular scraper unit 300 up / down or left / right via a means such as a cylinder.

[0076] In embodiments of this disclosure, the position adjustment unit 400 can fix the position of the modular doctor blade unit 300 or move the position of the modular doctor blade unit 300 over time. For example, the position adjustment unit 400 can move the modular doctor blade unit 300 away from the surface of the coating roller 200 over time. Therefore, the coating thickness can be changed continuously or discontinuously according to the length of the diaphragm, thereby producing a diaphragm with higher quality.

[0077] In embodiments of this disclosure, the coating apparatus 1 for the diaphragm may further include a measuring device (not shown) to measure the properties of the coating liquid, such as its viscosity, and the position adjustment unit 400 may further include a receiving device (not shown) to measure the properties of the coating liquid and adjust the position of the modular scraper unit 300 based on the measured data. Therefore, the amount of coating liquid applied to the substrate 10 can be adjusted according to the viscosity of the coating liquid.

[0078] In embodiments of this disclosure, a modular doctor blade unit 300 may be disposed between the conveying path of the substrate 10 conveyed in one direction and the coating roller 200. When the modular doctor blade unit 300 is disposed between the conveying path of the substrate 10 conveyed in one direction and the coating roller 200, specifically, when the modular doctor blade unit 300 is disposed on one side of the substrate 10 being conveyed to the coating roller 200, the modular doctor blade unit 300 may remove a portion of the coating liquid.

[0079] In embodiments of this disclosure, the coating apparatus 1 for the diaphragm may further include a slit mold 500 for supplying a second coating liquid 30 to the coating roller 200. For example... Figure 7As shown, the slit mold 500 can supply the second coating liquid 30 onto the coating liquid that has already had a portion of the coating liquid 20 removed by the modular scraper unit 300, or as... Figure 8 As shown, a second coating liquid 30 can be supplied to the coating liquid 20 before a portion of the coating liquid 20 is removed by the modular scraper unit 300.

[0080] In embodiments of this disclosure, the coating roller 200 may have a groove 201 to form an area for receiving the coating liquid 20. In this case, when a second coating liquid 30 with a different composition from the coating liquid 20 is supplied to the coating roller 200 through the slit mold 500, a coating with different compositions at various locations can be formed using only one coating device 1 for the diaphragm.

[0081] In addition, since the modular scraper unit 300 can have protrusions such as embossed patterns, the pattern of the coating can be controlled by adjusting the shape of the modular scraper unit 300 and the shape of the slit mold 500.

[0082] In embodiments of this disclosure, the coating apparatus 1 for the diaphragm may further include a back roller (not shown) opposite the coating roller 200, spaced apart from a substrate conveyed in one direction. In this case, it is easier to transfer the coating liquid to the substrate.

[0083] <Methods for Manufacturing a Diaphragm>

[0084] This disclosure provides a method for manufacturing a diaphragm.

[0085] The method for manufacturing a diaphragm according to this disclosure includes applying a coating liquid 20 to at least one surface of a substrate 20 using the coating equipment 1 described above for the diaphragm.

[0086] In embodiments of this disclosure, the method of manufacturing a diaphragm can vary the coating thickness, coating load, coating pattern, or two or more of these by adjusting the gap between the coating rollers 200 and the doctor blade 310 that are facing each other.

[0087] Figure 9 The figure shows the removal of a portion of the coating liquid 20 transferred to the coating roller 200 by using a coating roller 200 that does not have grooves 201 on its surface and a scraper 310 that does not have embossed patterns 311.

[0088] Specifically, the thickness of the coating liquid 20 transferred from the storage unit 100 to the surface of the coating roller 200 on the coating roller 200 can be a1, and as a portion of the coating liquid 20 is removed by the scraper 310, the thickness of the coating liquid 20 on the coating roller 200 can be a2 (where a1>a2).

[0089] Figure 10 The figure shows the removal of a portion of the coating liquid 20 transferred to the coating roller 200 by using a coating roller 200 without grooves on its surface and a scraper 310 with embossed protrusions 311.

[0090] Specifically, the coating liquid 20 transferred from the storage unit 100 to the surface of the coating roller 200 can have a thickness of b1 on the coating roller 200. As a portion of the coating liquid 20 is removed by the scraper 310, the coating liquid 20 can have an area with a thickness of b1 and an area with a thickness of b2 (where b1 > b2) on the coating roller 200. Specifically, the area where the coating liquid 20 is partially removed can have a thickness of b2 through the protrusions 311 of the embossed pattern, and the area where the coating liquid 20 is not removed can have the original thickness of b1.

[0091] Additionally, the area where the coating liquid 20 was partially removed is transferred to the substrate 10. In this case, although the flow time of the coating liquid may vary depending on the viscosity and physical properties of the coating liquid used, the thickness of the coating liquid 20 on the coating roller 200 can be substantially maintained on the substrate after a sufficient period of time.

[0092] Figure 11 The figure shows the removal of a portion of the coating liquid 20 transferred to the coating roller 200 by using a coating roller 200 having grooves 201 on its surface and a scraper 310 having protrusions without embossed patterns.

[0093] Specifically, the coating liquid 20 transferred from the storage unit 100 to the surface of the coating roller 200 can have a thickness of c1 on the coating roller 200. As a portion of the coating liquid 20 is removed by the doctor blade 310, the coating liquid 20 can have an area with a thickness of c1 and an area with a thickness of c2 (where c1 > c2) on the coating roller 200. Specifically, the area where the coating liquid 20 is partially removed by the doctor blade 310 can have a thickness of c2, and the area where the coating liquid 20 is not removed can have the original thickness of c1.

[0094] Additionally, the area where the coating liquid 20 on the coating roller 200 has been partially removed is transferred to the substrate 10. In this case, although the flow time of the coating liquid may vary depending on the viscosity and physical properties of the coating liquid used, the thickness of the coating liquid 20 on the coating roller 200 can be substantially maintained on the substrate after a sufficient period of time.

[0095] Figure 12 The figure shows the removal of a portion of the coating liquid 20 transferred to the coating roller 200 by using a coating roller 200 having grooves 201 on its surface and a scraper 310 having protrusions 311 with embossed patterns.

[0096] Specifically, the coating liquid 20 transferred from the storage unit 100 to the surface of the coating roller 200 can have a thickness of d1 on the coating roller 200. As a portion of the coating liquid 20 is removed by the scraper 310, the coating liquid 20 can have an area with a thickness of d1 and an area with a thickness of d2 (where d1 > d2) on the coating roller 200. Specifically, the area where the coating liquid 20 is partially removed by the scraper 310 can have a thickness of d2, and the area where the coating liquid 20 is not removed can have the original thickness of d1.

[0097] Additionally, the area where the coating liquid 20 on the coating roller 200 has been partially removed is transferred to the substrate 10. In this case, although the flow time of the coating liquid may vary depending on the viscosity and physical properties of the coating liquid used, the thickness of the coating liquid 20 on the coating roller 200 can be substantially maintained on the substrate after a sufficient period of time.

[0098] In embodiments of this disclosure, the step of applying the coating liquid may include changing the coating thickness, coating load, coating pattern, or two or more of these by replacing the squeegee 310 of the modular squeegee unit 300. Specifically, the coating thickness, coating load, and / or coating pattern on a substrate 10 may be changed by replacing the squeegee 310 of the modular squeegee unit 300.

[0099] In embodiments of this disclosure, the step of applying the coating liquid may include varying the coating thickness, coating load, coating pattern, or two or more of these along the length direction of the substrate 10 by adjusting the position of the modular squeegee unit 300 over time. Specifically, the amount of coating liquid 20 on the coating roller 200 can be adjusted by moving the modular squeegee unit 300 toward or away from the coating roller 200 over time, thereby forming a coating on the substrate 10 with varying thicknesses along the length direction of the substrate.

[0100] In embodiments of this disclosure, the properties of the coating liquid can be measured before the application of the coating liquid, and the position of the modular doctor blade unit can be adjusted based on the measured properties of the coating liquid. Specifically, the properties of the coating liquid can be measured, and the position of the modular doctor blade unit 300 can be adjusted based on the measured data to regulate the amount of coating liquid 20 on the coating roller 200, thereby adjusting the coating thickness and / or coating load on the substrate 10.

[0101] In embodiments of this disclosure, the method of manufacturing the diaphragm may include applying a second coating liquid to a coating roller using a second coating liquid supply device such as a slit mold, thereby forming a coating with different compositions at various locations.

[0102] In embodiments of this disclosure, prior to the step of applying the coating liquid to the substrate, the method of manufacturing the diaphragm may include preparing a coating liquid comprising an adhesive polymer and inorganic particles.

[0103] A coating liquid comprising an adhesive polymer and inorganic particles can be prepared by adding an adhesive polymer and inorganic particles to a solvent.

[0104] In embodiments of this disclosure, the solvent may include an aqueous solvent or an organic solvent.

[0105] In embodiments of this disclosure, the aqueous solvent may include water or an aqueous solvent containing water. Furthermore, when there are limitations on drying rate and temperature, methanol, ethanol, or isopropanol, which have boiling points lower than water, may be used as a co-solvent.

[0106] In embodiments of this disclosure, the organic solvent may include: cyclic aliphatic hydrocarbons including cyclopentane or cyclohexane; aromatic hydrocarbons including toluene, xylene, or ethylbenzene; ketones including acetone, ethyl methyl ketone, diisopropyl ketone, cyclohexanone, methylcyclohexane, or ethylcyclohexane; chlorinated aliphatic hydrocarbons including dichloromethane, chloroform, or carbon tetrachloride; esters including ethyl acetate, butyl acetate, γ-butyrolactone, or ε-caprolactone; acyl nitriles including acetonitrile or propionitrile; ethers including tetrahydrofuran or ethylene glycol diethyl ether; alcohols including methanol, ethanol, isopropanol, ethylene glycol, or ethylene glycol monomethyl ether; or amides including N-methylpyrrolidone or N,N-dimethylformamide. When considering the advantages of the drying process, the organic solvent may include acetone.

[0107] In embodiments of this disclosure, these organic solvents may be used alone or in combination. Among them, solvents with low boiling points and high volatility are particularly desirable because they are removed at low temperatures for a short time. Specifically, such solvents may preferably include acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene, N-methylpyrrolidone, or mixtures thereof.

[0108] In embodiments of this disclosure, the adhesive polymer is not limited to a specific type and may include any material that provides bonding strength between inorganic particles and between the porous coating and the porous polymer substrate. The adhesive polymer may include, for example, polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride-co-trichloroethylene, and polyvinylidene fluoride-co-chlorotrifluoroethylene. ethylene), poly(meth)acrylate, poly(meth)acrylate, poly(meth)acrylate, poly(n-propyl)acrylate, poly(meth)acrylate, poly(isopropyl)acrylate, poly(n-butyl)acrylate, poly(tert-butyl)acrylate, poly(sec-butyl)acrylate, poly(pentyl)acrylate, poly(2-ethylbutyl)acrylate, poly(2-ethylhexyl)acrylate, poly(n-octyl)acrylate, poly(isooctyl)acrylate, poly(isononyl)acrylate, poly(lauryl)acrylate, poly(tetradecyl)acrylate, poly(N-vinylpyrrolidone), polyacrylonitrile, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetatebutyrate, cellulose acetate propionate. Propionate, cyanoethyl pullullan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullullan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, or two or more thereof.

[0109] In embodiments of the present disclosure, the inorganic particles are not limited to specific particles and can include any electrochemically stable particles. That is, the inorganic particles that can be used in the present disclosure are not limited to specific types and can include any type of inorganic particles that do not undergo oxidation and / or reduction reactions within the operating voltage range of the applied electrochemical device (e.g., 0 to 5 V based on Li / Li+). In particular, when inorganic particles with a high dielectric constant are used as the inorganic particles, they can help increase the dissociation degree of electrolyte salts, such as lithium salts in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution.

[0110] For the above reasons, the inorganic particles preferably include high dielectric constant inorganic particles with a dielectric constant of 5 or higher, preferably 10 or higher. Non-limiting examples of inorganic particles with a dielectric constant of 5 or higher include: BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb z , w , x , y , x , y , x , y La x Zr 1-y Ti y O3 (PLZT, 0 < x < 1, 0 < y < 1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnium dioxide (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, TiO2, or a mixture thereof.

[0111] In addition, the inorganic particles can include inorganic particles having lithium ion transport ability, that is, inorganic particles containing lithium but not storing lithium and having the function of moving lithium ions. Non-limiting examples of inorganic particles having lithium ion transport ability include: lithium phosphate (Li3PO4); lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3); lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3); (LiAlTiP) x O y -based glass (0 < x < 4, 0 < y < 13), such as 14Li2O-9Al2O3-38TiO2-39P2O5; lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3); lithium germanium thiophosphate (Li x Ge y P z S w, where 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), such as Li 3.25 Ge 0.25 P 0.75 S4; lithium nitride (Li x N y , where 0 < x < 4, 0 < y < 2), such as Li3N; SiS2-based glass (Li x Si y S z , where 0 < x < 3, 0 < y < 2, 0 < z < 4), such as Li3PO4-Li2S-SiS2; P2S5-based glass (Li x P y S z , where 0 < x < 3, 0 < y < 3, 0 < z < 7), such as LiI-Li2S-P2S5; or mixtures thereof.

[0112] In addition, when inorganic particles are added, the inorganic particles can have a particle size in the range of 3 μm to 200 μm, and when applied to a porous polymer substrate, the D of the inorganic particles 50 is not limited to a specific range, but is preferably in the range of 0.1 μm to 1.5 μm to form a coating with a uniform thickness and optimal porosity. When the D of the inorganic particles 50 is less than 0.1 μm, the dispersibility may be reduced, and when the D of the inorganic particles 50 is greater than 1.5 μm, the inorganic coating may form a greater thickness.

[0113] The weight ratio of the binder polymer to the inorganic particles can be, for example, 50:50 to 99:1 or 70:30 to 95:5. When the weight ratio of the binder polymer to the inorganic particles falls within the above range, a porous coating with optimal pore size and porosity can be formed, and the heat resistance of the separator can be improved.

[0114] In an embodiment of the present disclosure, at 23 °C, the viscosity of the coating solution can be 5 cps to 30 cps, or 10 cps to 20 cps. When the viscosity of the coating solution falls within the above range, the coating can have a clearer pattern shape. In this case, the viscosity can be measured, for example, at 23 °C using a Brookfield viscometer (DV2T viscometer, 12 rpm, spindle 24).

[0115] In an embodiment of the present disclosure, the substrate can include, for example, polyethylene, polypropylene, polyimide, polyethylene terephthalate, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, or two or more of them.

Claims

1. A coating apparatus for a diaphragm, comprising: A storage unit for containing the coating liquid; A coating roller configured to transfer the coating liquid from the storage unit to at least one surface of a substrate being conveyed in one direction; as well as A modular doctor blade unit configured to remove a portion of the coating liquid from the surface of the coating roller. The modular scraper unit includes at least one scraper. The coating roller has multiple grooves with an engraved pattern on the surface, and The coating roller rotates in the same direction as the conveying direction of the substrate.

2. The coating apparatus for a diaphragm according to claim 1, The scraper has raised sections with embossed patterns.

3. The coating apparatus for a diaphragm according to claim 1, The modular scraper unit includes at least two scrapers.

4. The coating apparatus for a diaphragm according to claim 3, The modular scraper unit further includes a scraper rotating part that rotates the plurality of scrapers.

5. The coating apparatus for a diaphragm according to claim 1, The modular scraper unit includes at least two scrapers, and The at least two scrapers have protrusions with different embossed patterns.

6. The coating apparatus for a diaphragm according to claim 1, further comprising: A position adjustment unit for adjusting the position of the modular scraper unit.

7. The coating apparatus for a diaphragm according to claim 1, The modular scraper unit is disposed between the conveying path of the substrate being conveyed along the direction and the coating roller.

8. The coating apparatus for a diaphragm according to claim 1, further comprising: A slit mold for supplying a second coating liquid to the coating roller.

9. A method for manufacturing a diaphragm, the method comprising: The step of applying a coating liquid to at least one surface of a substrate using the coating apparatus for a diaphragm as defined in claim 1.

10. The method for manufacturing a diaphragm according to claim 9, The coating thickness, coating load, coating pattern, or two or more of these can be changed by adjusting the gap between the coating rollers and the doctor blade that are facing each other.

11. The method for manufacturing a diaphragm according to claim 9, The step of applying the coating liquid includes changing the coating thickness, coating load, coating pattern, or two or more of them by replacing the blade of the modular blade unit.

12. The method for manufacturing a diaphragm according to claim 9, The step of applying the coating liquid includes varying the coating thickness, coating load, coating pattern, or two or more of these along the length of the substrate by adjusting the position of the modular scraper unit over time.

13. The method for manufacturing a diaphragm according to claim 9, Prior to the step of applying the coating liquid, the method includes measuring the properties of the coating liquid and adjusting the position of the modular scraper unit based on the measured properties of the coating liquid.

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