Modular coating bar for pattern coating and coating device comprising the same

Abstract

The coating bar according to this disclosure comprises an assembly of units, making it easy to extend or shorten the length of the coating bar. Therefore, it can be used to manufacture diaphragms of different sizes. Furthermore, the coating bar according to this disclosure includes a third portion having a cylindrical tube shape capable of changing position; thus, the coating pattern can be changed by adjusting the position of the third portion within the coating bar without replacing the coating bar in the coating apparatus, thereby improving process efficiency.

Description

Technical Field

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2024-0093836, filed in Korea on July 16, 2024, the disclosure of which is incorporated herein by reference in its entirety. This disclosure relates to a modular meller rod for pattern coating and a coating apparatus including the same. Furthermore, this disclosure relates to a method for manufacturing a diaphragm using the apparatus. Background Technology

[0002] Typically, a separator is inserted between the positive and negative electrodes of a lithium-ion secondary battery to prevent short circuits during repeated charging and discharging. The separator can be manufactured using a porous polymer substrate alone, or by applying a slurry-like coating containing inorganic particles and a binder polymer to at least one surface of the porous polymer substrate and drying the coating to form an inorganic coating.

[0003] Many different methods can be used to apply coating liquids to substrates, such as dip coating, gravure coating, or die coating. Depending on the intended use or battery specifications, inorganic coatings can be applied in a predetermined pattern. However, because the coating mayer bars of the coating machine have a fixed shape, changing the coating machine is unavoidable in order to change the shape or width of the pattern. Furthermore, when using a full-surface coating method with mayer bars of a constant diameter, losses occur during slitting (cutting) into final products of predetermined dimensions, resulting in lower manufacturing efficiency. Summary of the Invention

[0004] Technical issues

[0005] This disclosure is designed to address the aforementioned problems; therefore, it aims to provide a variable coating bar for adjusting the coating width and a coating apparatus including the coating bar. Furthermore, this disclosure aims to provide a coating method using this coating apparatus to coat porous coatings in various patterns without changing the coating bar.

[0006] Technical solution

[0007] This disclosure relates to a coating rod. In embodiments of this disclosure, the coating rod is a coating rod comprising one or more units, wherein each unit includes a first portion, a second portion, and a third portion. Each of the first portion, the second portion, and the third portion has a cylindrical shape. The first portion and the second portion have different diameters. The first portion and the second portion have ends that are rotatably connected to each other on an axial axis. The third portion has a hollow portion extending through the length direction. The third portion is configured to cover the outer side of the first portion or the second portion, or the outer side of both the first portion and the second portion, and the third portion is slidably mounted on the outer side of the first portion or the second portion, or the outer side of both the first portion and the second portion.

[0008] In the foregoing, the unit may include one or more first parts, one or more second parts, and one or more third parts.

[0009] In any of the above aspects, the first portion may have a larger diameter than the second portion.

[0010] In any of the above aspects, the diameter difference between the first part and the second part may be 10 mm or greater.

[0011] In any of the above aspects, the inner diameter of the third part may be equal to or greater than the outer diameter of the first part.

[0012] In any of the above aspects, in the unit, the total length of the third part may be equal to or greater than the total length of the second part.

[0013] In any of the foregoing aspects, the unit may include the first portion at each of its two ends, and one or more second portions may be rotatably connected coaxially between the two first portions.

[0014] In any of the above aspects, two second parts may be connected between the two first parts, and two third parts may respectively cover the two first parts, the length of each third part being equal to or greater than the length of each adjacent second part.

[0015] In any of the above aspects, at least one of the first part and the second part may include a fixing part to support the third part.

[0016] In any of the above aspects, the fixing part may be configured to retract into the body of each part to be flush with the surface of the body, and then extend outward to support the inner surface of the third part.

[0017] In addition, a coating apparatus is provided, comprising a coating rod according to any of the above aspects.

[0018] In any of the foregoing aspects, the coating apparatus may further include a coating head and a receiving chamber located inside the coating head, the receiving chamber containing a coating liquid, and the coating rod may be rotatably mounted.

[0019] In any of the foregoing aspects, the coating apparatus may further include an ultrasonic generator located inside the coating head and / or inside the receiving chamber, the ultrasonic generator being configured to apply ultrasonic waves to the coating liquid contained in the receiving chamber.

[0020] The embodiments described above in this disclosure can be implemented independently of each other. Furthermore, the embodiments described above in this disclosure can be implemented in combination.

[0021] Beneficial effects

[0022] The coating rod according to this disclosure comprises an assembly of units that allow for easy extension or reduction of the coating rod's length. Therefore, it can be used to manufacture diaphragms of different sizes.

[0023] Furthermore, since the coating bar according to this disclosure includes a third part having the shape of a cylindrical tube capable of changing position, the coating pattern can be changed by adjusting the position of the third part in the coating bar without replacing the coating bar in the coating apparatus, thereby improving process efficiency. Attached Figure Description

[0024] The accompanying drawings illustrate exemplary embodiments of this disclosure and are used together with the above disclosure to provide a better understanding of the technical aspects of this disclosure. Therefore, this disclosure should not be construed as being limited to any of the drawings.

[0025] Figure 1 The structure of a coating apparatus according to an embodiment of the present disclosure is illustrated schematically.

[0026] Figures 2a to 4 The structure of a unit according to an embodiment of this disclosure is illustrated schematically.

[0027] Figure 5 This is a perspective view of a unit according to an embodiment of the present disclosure.

[0028] Figures 6 to 10 The diagram schematically illustrates a coating process using a coating apparatus that includes a coating bar according to an embodiment of the present disclosure.

[0029] Figure 11A portion of a coating rod 200 is schematically shown, the coating rod having a shape in which a line 31 is spirally wound around the surface of any portion 20. Figure 12 The application of the coating liquid using the coating stick is shown.

[0030] Figure 13 A portion of a coating rod 200 is shown, the coating rod having a plurality of annularly connected surfaces 41. Figure 14 The application of the coating liquid using the coating stick is shown. Detailed Implementation

[0031] It should be understood that the terms or words used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but should be interpreted in accordance with the meanings and concepts corresponding to the technical concept of this disclosure, based on the principle that inventors are allowed to appropriately define terms for the best interpretation.

[0032] The terminology used herein is for describing exemplary embodiments of the present disclosure and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms include the plural forms.

[0033] In this application, terms such as “up,” “down,” “left,” “right,” “inner,” and “outer” denote directions in the referenced figures and should not be limiting. The terms “inner” and “outer” respectively indicate directions toward or away from the geometric center of the device, system, or component thereof. These terms include the words listed above, their derivatives, and words with similar meanings.

[0034] In this application, when an element is said to be located on another element, the element is in contact with the other element, and an intermediate element may be present.

[0035] The terms “comprising,” “including,” or “having” as used in this application indicate the presence of the said element, but do not exclude the presence or addition of one or more other elements, unless the context clearly indicates otherwise.

[0036] Coating apparatus

[0037] This disclosure provides a coating apparatus.

[0038] Figure 1 The structure of a coating apparatus according to an embodiment of the present disclosure is illustrated schematically.

[0039] According to one aspect of this disclosure, the coating apparatus 10 includes: a coating head 100; a receiving chamber 110 located inside the coating head 100 and configured to receive a coating liquid; and a coating rod 200 configured to transfer the coating liquid from the receiving chamber 110 to at least one surface of a substrate S being conveyed in one direction. The coating rod 200 is rotatably mounted on the coating head 100.

[0040] In embodiments of this disclosure, an ultrasonic generator (not shown) may be further provided inside the coating head 100 to apply ultrasonic waves to the coating liquid contained in the receiving chamber 110.

[0041] In embodiments of this disclosure, the coating rod 200 transfers a coating liquid from a receiving chamber to at least one surface of a substrate S being conveyed in one direction. Figure 1 In this context, MD direction represents the machine direction.

[0042] although Figure 1 The substrate S is shown for reference, but should not be construed as limiting the coating apparatus 10 of this disclosure. The substrate S may be a porous polymer substrate used to manufacture separators for secondary batteries. The coating liquid may be a slurry containing a binder polymer, inorganic particles, and a solvent. A separator comprising an inorganic coating on a porous polymer substrate can be manufactured by coating the coating liquid onto at least one surface of the substrate S. The coating apparatus 10 of this disclosure is suitable for separator coating.

[0043] In embodiments of this disclosure, the coating apparatus 10 can be supplied with coating liquid from an external source and contain the coating liquid in a receiving chamber 110. The coating liquid contained in the receiving chamber 110 comes into contact with the coating rod 200, and the coating liquid on the coating rod 200 is transferred to at least one surface of the substrate S being conveyed in one direction.

[0044] The coating bar unit described in this disclosure can be individually formed as coating bar 200, or two or more coating bar units can be assembled into one unit to form coating bar 200. The coating bar is rotatably mounted on the coating head.

[0045] In embodiments of this disclosure, the front portion of the coating head 100 refers to the outer surface of the coating head 100 that is close to the substrate that is conveyed in one direction and before contacting the coating bar 200, and the rear portion of the coating head 100 refers to the outer surface of the coating head 100 that is close to the substrate that is conveyed in one direction and after contacting the coating bar 200.

[0046] <Coating stick>

[0047] In this disclosure, the coating rod 200 is a modular system comprising one or more units. The coating rod 200 includes one or more units 210, 220 described below, and the length of the coating rod 200 can be adjusted by combining these units. That is, the total length of the coating rod 200 can be extended when one unit of unit 210, 220, 230 is joined to another unit at its end. These units can be connected or joined to each other with substantially no gaps. In this application, substantially no gaps can mean a distance between units of 5 mm or less, 3 mm or less, 1 mm or less, 500 μm or less, 300 μm or less, or 100 μm or less. Furthermore, the coating width can be extended to the length of the extended coating rod 200. The units included in the coating rod 200 rotate synchronously and coaxially. In this disclosure, when the coating rod 200 includes multiple units, the units located at both ends of the coating rod 200 may have fasteners (not shown) designed to be rotatably mounted on a coating head at the outer ends of each unit.

[0048] In embodiments of this disclosure, the unit includes a first cylindrical portion having a larger diameter and a second cylindrical portion having a smaller diameter. The first and second portions are positioned such that their ends are in close contact with each other with substantially no gap, and the first and second portions are rotatably connected coaxially. The first and second portions are configured to rotate synchronously, and they have the same angular velocity of rotation. The first and second portions are connected in a stepped manner due to their different diameters.

[0049] In embodiments of this disclosure, a unit may include one or more first portions and one or more second portions. In this case, the first portions may be disposed at each of the two ends of the unit, and one or more second portions may be combined between the first portions.

[0050] Furthermore, the unit includes a third portion having a hollow cylindrical shape. The third portion may cover either the first portion or the second portion and is configured to move between the first portion and the second portion. The third portion rotates synchronously with the first portion and / or the second portion. The third portion has a tubular shape with an inner diameter at least equal to or greater than the diameter of the first portion and is configured to slide between the first portion and the second portion.

[0051] The third portion may have a length equal to or greater than that of the second portion to cover the entire second portion. In embodiments of this disclosure, the coating rod may include the same number of third portions as the number of first portions in at least one unit.

[0052] In embodiments of this disclosure, the first portion and the second portion may have the same or different lengths. When a unit includes two or more first portions, each first portion may have the same or different lengths. When a unit includes two or more second portions, each second portion may have the same or different lengths.

[0053] In embodiments of this disclosure, each of the first and second portions may include a fixing portion 300 to secure the third portion. For example, the fixing portion may be formed in a retractable manner within the body of the respective portion. That is, the fixing portion may be configured to retract into the body of each portion to be flush with the surface of the body, and then extend outward to support the inner surface of the third portion. The fixing portion has an end that contacts the inner surface of the third portion, and this end may be resilient. Each portion may include one or more fixing portions, and the fixing portions may be configured to retract and extend by mechanical operation and / or electrical signals. The fixing portions are not limited to a specific number or location and may be suitably arranged. Through the fixing portions, the third portion can rotate synchronously with the other portions as the coating rod rotates. When the fixing portions retract, preferably, the surface of the fixing portions is substantially flush with the surfaces of the respective portions to avoid creating steps on the coating surface due to the fixing portions.

[0054] Here, the first and third portions can form coated areas, and the second portion can form uncoated areas. That is, the slurry can be applied to the substrate while moving along the surface of the first and / or third portions in the chamber, and since the second portion does not contact the slurry, no slurry is applied to the substrate surface corresponding to the area where the second portion moves.

[0055] In this disclosure, the difference between the outer diameter of the third part and the diameter of the first part can be 20 μm or less. When the difference is greater than 20 μm, the coating thickness may be uneven due to the larger step between the third part and the first part. Additionally, the difference between the diameter of the first part and the diameter of the second part can be 10 mm or greater. When the difference is less than 10 mm, it is difficult to effectively achieve the desired level of pattern coating.

[0056] In embodiments of this disclosure, the unit may include one or more first portions at one end and one or more second portions at the other end. In this case, the unit may include one or more third portions configured to slide between the first and second portions. The total length of the third portions may be equal to or greater than the total length of the second portions.

[0057] When the total length of the third part is greater than the total length of the second part, as the third part slides to cover the second part, the end of the third part can overlap with the first part, and the third part can be supported by the first part. Alternatively, in one embodiment, the total length of the first part can be the same as or different from the total length of the third part.

[0058] Figure 2a , Figure 2b and Figure 2c Each of the examples shows a unit 210 comprising a first part 211, a second part 212, and a third part 213 (Example A). See also... Figure 2a , Figure 2b and Figure 2c The first part 211 and the second part 212 are rotatably connected on the same axis, and a third part 213 is slidably movable between the first part and the second part. Figure 2a The third part shows that it covers the second part. Figure 2b This shows the third part moving from the second part to the first part. Figure 2c The third part is shown to cover the first part.

[0059] In embodiments of this disclosure, the length of the third portion may be equal to or greater than the length of the second portion. The length of the second portion may be the same as or different from the length of the first portion. The length of the third portion may be the same as or different from the length of the first portion. From the perspective of coating surface uniformity, the length of the third portion is preferably the same as the length of the first portion. When the length of the third portion is less than the length of the first portion, steps may be formed at the ends of the third and first portions as the third portion slides toward the first portion, resulting in poor coating surface uniformity. However, this may depend on the viscosity and spreadability of the coating liquid. When the viscosity of the coating liquid is low or the coating liquid spreads well, the coating liquid can be applied uniformly even though there are large steps between the first and third portions.

[0060] In embodiments of this disclosure, the unit may include a first portion at each of its two ends, and one or more second portions may be synchronously and coaxially rotatably connected between the two first portions. In this case, the unit may include one or more third portions configured to slide between the first and second portions. Here, the total length of the third portions may be equal to or greater than the total length of the second portions. When the unit includes two third portions, the length of at least one third portion may be equal to or greater than the total length of the second portions.

[0061] Figure 3A unit 220 (Example B) is schematically shown, comprising two first portions 221a and 221b and a second portion 222 connecting the two first portions 221a and 221b. Here, the unit includes a third portion 223 covering either of the two first portions, and the length of the third portion is equal to or greater than the length of the second portion.

[0062] Figure 4 and Figure 5 Another implementation of this disclosure is shown (Example C). Figure 4 This is a side view. Figure 5 This is a perspective view. (Refer to...) Figure 4 and Figure 5 Unit 230 includes: two first portions 231a and 231b; two second portions 232a and 232b connected between the two first portions 231a and 231b; and two third portions 233a and 233b respectively covering the first portions 231a and 231b. Referring to this, the length of each third portion is equal to or greater than the length of each adjacent second portion. Each third portion can be configured to move from both ends to the central portion to cover the second portions. In embodiments of this disclosure, the third portions 233a and 233b can have different inner diameters, and when covering the second portions, they can overlap and support each other. Furthermore, in this case, the third portions 233a and 233b can overlap (not shown) with the ends of the first portions 231a and 231b, respectively. The lengths of the third portions 233a and 233b can be appropriately adjusted to form this structure.

[0063] In embodiments of this disclosure, the coating rod 200 may include one unit or a combination of two or more units. The coating rod 200 may include a plurality of units arranged and connected along the width direction of the diaphragm substrate to be coated, and has a width corresponding to or greater than the total width of the diaphragm substrate.

[0064] Figures 6 to 10 A coating rod 200a is schematically shown formed by connecting three units 230 according to Example C. To clearly illustrate the structure of the coating rod 200, other components of the coating apparatus 10 are indicated by dashed lines. For the purpose of describing this disclosure, the unit shown on the left side of the figure is referred to as unit a 230a, the unit shown on the right side is referred to as unit b 230c, and the unit located between unit a and unit c is referred to as unit b 230b. Here, the first module and the second module are shown as having the same length, but are not limited thereto; the lengths of the first module and the second module may be the same or different.

[0065] Figure 6The process (Example C-1) of applying a coating liquid to the surface of a substrate using a coating apparatus including a coating rod 200a (Example C), the coating rod having a structure in which each third portion of each unit 230a, 230b, 230c moves to its corresponding second portion to cover the second portion. Referring to this, the outer surface of the coating rod is formed by a combination of portions 1 and 3, and the coating formed on the surface of the substrate has a width corresponding to the total length of the coating rod, thereby forming a coating area C1 over the entire length of the coating rod. Because portions 1 and 3 have different diameters, the entire coating rod is not perfectly flat, and there may be steps between portions 1 and 3. However, the coating surface can be made flat and stepless by controlling the spreadability of the coating liquid.

[0066] Figure 7 The process of applying a coating liquid to the surface of a substrate using a coating apparatus including a coating rod 200a (Example C) is illustrated (Example C-2). This coating rod has a structure in which a third portion of unit b 230b covers a first portion, and the third portions of units a 230a and c 230c move to cover a second portion. Referring to this, in unit b, the second portion with a smaller diameter is exposed, so the corresponding area is not coated with the coating liquid and remains an uncoated area C2, while the coating liquid is applied to both sides of the uncoated area in the width direction by units a and c, thereby forming a coated area C1.

[0067] Figure 8 The process of applying a coating liquid to the surface of a substrate using a coating apparatus including a coating rod 200a (Example C) is illustrated (Example C-3). The coating rod has a structure in which the third portions of units a 230a and c 230b cover the first portion, and the third portion of unit b moves to cover the second portion. Referring to this, the second portion of unit b is covered by the third portion, thereby applying the coating liquid to the substrate. Additionally, the surfaces corresponding to the second portions of units a and c are not coated with the coating liquid and remain as uncoated areas C2. The coating liquid is applied to both sides of the uncoated area in the width direction by the third portions of units a and c, respectively, thereby forming coated areas C1.

[0068] Figure 9The process (Example C-4) of applying a coating liquid to the surface of a substrate using a coating apparatus including a coating rod 200a (Example C), the coating rod having a structure in which the third portions of unit a and unit b move to cover the second portions, is illustrated. Referring to this, the second portions of unit a and unit b are covered by the third portions, thereby applying the coating liquid to the substrate. Additionally, the surface corresponding to the second portion of unit c is not coated with the coating liquid and remains an uncoated area, and the coating liquid is applied to both sides of the uncoated area in the width direction by the third portions, thereby forming a coated surface.

[0069] Figure 10 The process (Example C-5) of applying a coating liquid to the surface of a substrate using a coating apparatus including a coating rod 200a (Example C), wherein the coating rod has a structure in which any one of the third portions of each unit moves to cover a first portion and another third portion moves to cover a second portion. Referring to this, the surface corresponding to the exposed portion of the second portion in each unit that is not covered by the third portion is not coated with the coating liquid and remains an uncoated area, and a coated surface is formed by applying the coating liquid to both sides of the uncoated area in the width direction by the first and third portions.

[0070] Additionally, in embodiments of this disclosure, the coating rod 200 may be a wire bar with wire wound around its surface, or it may have a specific pattern. For example, the coating rod 200 may be a mayer bar type. A surface pattern may be provided to uniformly apply the coating liquid. Alternatively, the coating rod 200 may not have a specific pattern on its surface. In this application, the surface shape of the coating rod may follow the surface shape of each portion as described below. For example, when each portion is prepared in the shape of a wire bar, the coating rod 200 formed by combining them may exhibit the shape of a wire bar.

[0071] Figure 11 A portion of a coating rod 200 is schematically shown, the coating rod having a shape in which a line 31 is spirally wound around the surface of any portion 20. Figure 12 The application of the coating liquid using the coating stick is shown. On the other hand, Figure 13 A portion of a coating rod 200 is shown, the coating rod having a plurality of annularly connected surfaces 41 on the surface of each portion 20. Figure 14 The application of the coating liquid using the coating stick is shown.

[0072] In embodiments of this disclosure, a coating rod is mounted on a coating head 100 and configured to coat a slurry onto a conveyed diaphragm and adjust the coating pattern of the slurry coated on the diaphragm.

[0073] In addition, in order to allow the coating liquid to contact the coating rod 200 in the receiving chamber 110, the receiving chamber 110 may be additionally equipped with an auxiliary device (not shown) for pushing the coating liquid so that the coating liquid is positioned close to the coating rod 200.

[0074] In embodiments of this disclosure, the ultrasonic generator 120 is used to generate ultrasonic waves, and its type and shape are not limited to a particular one.

[0075] In embodiments of this disclosure, the ultrasonic generator 120 can generate ultrasonic waves to induce vibrations in the solvent of the coating liquid. These vibrations can generate and eliminate microbubbles to produce energy, which can then be used to break up agglomerations between inorganic particles and the binder polymer in the coating liquid. The ultrasonic generator 120 can help to uniformly disperse solids in the solvent within the coating liquid. In particular, the ultrasonic generator 120 can generate ultrasonic waves sufficient to separate and break up agglomerations of inorganic particles.

[0076] Additionally, in embodiments of this disclosure, the coating apparatus 10 may further include a coating liquid tank located outside the coating head 100 and configured to supply the coating liquid to the receiving chamber 110 via a delivery conduit.

[0077] In embodiments of this disclosure, the coating apparatus 10 may further include a collection unit (not shown) located on the outer surface of the coating head 100 and configured to coat a substrate (not shown, see [link]). Figure 1 After at least one surface of 2) is coated, the remaining coating liquid is conveyed along the outer surface of the coating head 100 and contained therein. The coating head 100 may have an incline on its outer surface. Through this incline, the remaining coating liquid may flow downward along the surface of the coating head 100 and collect in the collection unit 140.

[0078] <Methods for Manufacturing Diaphragms>

[0079] This disclosure allows the use of a coating rod according to this disclosure and a coating apparatus including the coating rod to manufacture a diaphragm.

[0080] The method for manufacturing the diaphragm disclosed herein involves supplying a coating liquid comprising an adhesive polymer, inorganic particles, and a solvent to a receiving chamber 110 of a coating apparatus 1 (step S10).

[0081] In embodiments of this disclosure, specifically, the adhesive polymer and inorganic particles can be added to a solvent and mixed together to prepare a coating solution. The solids content of the coating solution can be adjusted from 5 wt% to 70 wt% based on a 100 wt% coating solution, but is not particularly limited thereto. The viscosity of the coating solution can be in the range of 10 cps to 50 cps at 25°C, but is not particularly limited thereto. In this case, for example, the viscosity of the coating solution can be measured at 25°C using a Brookfield viscometer (DV2T viscometer, 1000 rpm, spindle 63). The surface of the coating rod according to this disclosure may have minute steps between sections. However, as the coating solution spreads uniformly through surface tension, the coating solution can fill the minute steps on the rod surface and distribute evenly. Therefore, the concentration and viscosity of the coating solution can be controlled to ensure proper spreadability, thereby maintaining a consistent thickness and uniform quality. Taking into account the spreadability of the coating solution, the solids content can be adjusted to an appropriate range.

[0082] In embodiments of this disclosure, the method of supplying the coating liquid to the receiving chamber 110 is not limited to a specific one. For example, the coating liquid may be supplied to the receiving chamber 110, or the prepared coating liquid may be supplied to the coating liquid tank 200 first, and then supplied to the receiving chamber 110 through the delivery pipe 210.

[0083] In embodiments of this disclosure, the binder polymer enhances the mechanical properties of the final formed membrane, such as flexibility and elasticity, and faithfully functions as a binder to connect and stably hold the inorganic particles together, thereby helping to prevent degradation of the mechanical properties in the membrane. The glass transition temperature (T) of the binder polymer is also mentioned. g It can operate within a temperature range of -200℃ to 200℃.

[0084] Furthermore, the binder polymer does not necessarily have to be ionicly conductive, but using a polymer with ionic conductivity can further improve the performance of the lithium-ion secondary battery. Therefore, the binder polymer can include polymers with the highest possible dielectric constant. In fact, the degree of dissociation of a salt in an electrolyte solution depends on the dielectric constant of the electrolyte solvent; therefore, a higher dielectric constant of the binder polymer allows for a greater degree of dissociation of the salt in the electrolyte solution. The dielectric constant of the binder polymer can range from 1.0 to 100 (measurement frequency = 1 kHz), specifically, it can be equal to or greater than 10.

[0085] In embodiments of this disclosure, the binder polymer can gel during liquid electrolyte filling and exhibits a high degree of electrolyte swelling. The solubility index of the binder polymer, i.e., the Hildebrand solubility parameter, can range from 15 to 45 MPa. 1 / 2 15 to 25 MPa 1 / 2 30 to 45 MPa 1 / 2 Within the range described above. In embodiments of this disclosure, when a hydrophilic polymer with a high concentration of polar groups is used instead of a hydrophobic polymer such as a polyolefin, the solubility index may fall within the aforementioned range. In this case, when the solubility index is below the lower limit of the aforementioned range or exceeds the upper limit, it may lead to undesirable swelling of the commonly used battery liquid electrolyte.

[0086] In embodiments of this disclosure, inorganic particles are stacked in contact with each other and held together by an adhesive polymer, thereby forming an interstitial volume between the inorganic particles, which becomes a void forming a pore. The adhesive polymer can bind the inorganic particles together to adhere them and connect and hold them together. Furthermore, the pores in the membrane can be formed by the voids created by the interstitial volume between the inorganic particles, which can be spaces defined by inorganic particles that are substantially in close contact with each other within a structure of close-packed or densely packed inorganic particles.

[0087] In embodiments of this disclosure, the adhesive polymer is not limited to a specific type and may include any type of adhesive polymer commonly used in the relevant technical field. The adhesive polymer may include, for example, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, amylopectin, carboxyl methyl cellulose, or two or more of these.

[0088] In this context, the adhesive polymer can comprise either a particulate adhesive or a soluble adhesive. When the adhesive polymer is a particulate adhesive, it is insoluble in the solvent. When the adhesive polymer is a soluble adhesive, it dissolves in the solvent. In this case, the solvent can comprise either an aqueous solvent or an organic solvent.

[0089] In embodiments of this disclosure, the inorganic particles are not limited to a specific type and may include any electrochemically stable inorganic particles. That is, the inorganic particles that can be used in this disclosure are not limited to a specific type and may 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., 0V to 5V based on Li / Li⁺). In particular, when inorganic particles with a high dielectric constant are used, it can help to increase the degree of dissociation of electrolyte salts, such as lithium salts, in liquid electrolytes, thereby improving the ionic conductivity of the electrolyte solution.

[0090] Due to the above reasons, the inorganic particles preferably include high dielectric constant inorganic particles having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include: BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x 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.

[0091] In addition, the inorganic particles may include inorganic particles having the ability to transport lithium ions, 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 the ability to transport lithium ions 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 , 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 , 0 < x < 4, 0 < y < 2), such as Li3N; SiS2 - based glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), such as Li3PO4 - Li2S - SiS2; P2S5 - based glass (Li x Py S z , where \(0 \lt x \lt 3\), \(0 \lt y \lt 3\), \(0 \lt z \lt 7\), such as LiI - Li₂S - P₂S₅; or a mixture thereof.

[0092] In addition, the average particle size D of the inorganic particles (single particles) 50 is not limited to a specific range, but preferably ranges from 0.1 μm to 1.5 μm to form a coating with a uniform thickness and optimal porosity. When the average particle size of the inorganic particles is below the lower limit, the dispersibility may decrease, and when the average particle size of the inorganic particles exceeds the upper limit, the thickness of the inorganic coating may increase.

[0093] In an embodiment of the present disclosure, based on the 100 wt% solid content of the coating liquid, inorganic particles may be included in an amount of 50 wt% or more.

[0094] In an embodiment of the present disclosure, the solvent may include an aqueous solvent or an organic solvent.

[0095] In an embodiment of the present disclosure, the aqueous solvent may include water, or an aqueous solvent containing water. In addition, when there are limitations on the drying speed and temperature, methanol, ethanol, or isopropanol with a boiling point lower than water may be used simultaneously.

[0096] In an embodiment of the present disclosure, the organic solvent may include: cycloaliphatic hydrocarbons including cyclopentane or cyclohexane; aromatic hydrocarbons including toluene, xylene, or ethylbenzene; ketones including acetone, ethyl methyl ketone, diisopropyl ketone, cyclohexanone, methyl cyclohexanone, or ethyl cyclohexanone; 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 in the drying process, the organic solvent may include acetone.

[0097] In an embodiment of the present disclosure, the above - listed organic solvents may be used alone or in combination. Among them, solvents with a relatively low boiling point and high volatility are particularly desirable because they are removed at low temperature in a short time. Specifically, such solvents may preferably include acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene, N - methylpyrrolidone, or a mixture thereof.

[0098] Subsequently, the coating liquid is transferred onto at least one surface of a substrate conveyed in one direction (step S20).

[0099] The substrate can be a porous polymer substrate used to manufacture separators for secondary batteries. The porous substrate can electrically insulate the positive and negative electrodes, preventing short circuits caused by contact between the electrodes, and providing a path for lithium ion movement. For example, the porous substrate can include a polymer membrane or nonwoven fabric, comprising, but not limited to, one or more polymer resins selected from the group consisting of polyolefins such as polyethylene or polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene ether, polyphenylene sulfide, and polyvinylnaphthalene. The porous substrate can include, but is not limited to, a single-layer polymer membrane or nonwoven fabric, and can include multilayer polymer membranes or nonwoven fabrics.

[0100] Furthermore, in embodiments of this disclosure, the step of applying ultrasound to the coating liquid can be performed before applying the coating liquid. The method of applying ultrasound to the coating liquid is not limited to a specific one, but for example, ultrasound can be applied to the coating liquid using the ultrasound generator (not shown) described above.

[0101] The embodiments described above in this disclosure can be implemented independently of each other. Furthermore, the embodiments described above in this disclosure can be implemented in combination.

[0102] [List of Reference Markers]

[0103] 10: Coating device; 2: Substrate; 100: Coating head; 110: Receiving chamber;

[0104] 200, 200a: Coating rods.

Claims

1. A coating rod, comprising: One or more units, The unit comprises a first part, a second part, and a third part, each of which has a cylindrical shape. The first part and the second part have different diameters. The first part and the second part have ends that are rotatably connected to each other on the same axis, and The third portion has a hollow portion extending through the length direction, the third portion is configured to cover the outer side of the first portion or the second portion, or the outer side of both the first portion and the second portion, and the third portion is slidably mounted on the outer side of the first portion or the second portion, or the outer side of both the first portion and the second portion.

2. The coating rod according to claim 1, The unit includes one or more first parts, one or more second parts, and one or more third parts.

3. The coating rod according to claim 1, The first part has a larger diameter than the second part.

4. The coating rod according to claim 1, The diameter difference between the first part and the second part is 10 mm or greater.

5. The coating rod according to claim 1, The inner diameter of the third part is equal to or greater than the outer diameter of the first part.

6. The coating rod according to claim 1, In the unit, the total length of the third part is equal to or greater than the total length of the second part.

7. The coating rod according to claim 1, The unit includes the first portion at each of its two ends, and one or more second portions are rotatably connected coaxially between the two first portions.

8. The coating rod according to claim 7, Two second parts are connected between the two first parts, and two third parts respectively cover the two first parts, with the length of each third part being equal to or greater than the length of each adjacent second part.

9. The coating rod according to claim 1, At least one of the first and second parts includes a fixing part to support the third part.

10. The coating rod according to claim 9, The fixing part is configured to retract into the body of each part to be flush with the surface of the body, and then extend outward to support the inner surface of the third part.

11. A coating apparatus comprising a coating rod according to any one of claims 1 to 10.

12. The coating apparatus according to claim 11, The coating apparatus further includes: The coating head and a receiving chamber located inside the coating head, the receiving chamber containing the coating liquid. The coating rod is rotatably mounted.

13. The coating apparatus according to claim 12, further comprising: An ultrasonic generator located inside the coating head and / or inside the receiving chamber, the ultrasonic generator being configured to apply ultrasonic waves to the coating liquid contained in the receiving chamber.

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