Coating rod and method of manufacturing a separator using the same

Abstract

The present disclosure relates to a coating rod and a method for manufacturing a separator using the same. The coating rod according to the present disclosure can form a coating layer having regions of different thicknesses by one coating. In addition, the method for manufacturing a separator according to the present disclosure includes forming a porous coating layer using a predetermined coating rod to manufacture a separator including a porous coating layer having regions of different thicknesses. Specifically, the present disclosure manufactures a separator having a greater thickness at both ends than at the center, thereby avoiding insufficient adhesion strength at both ends in a lateral direction in adhesion between the separator and an electrode and exhibiting uniform adhesion strength across the entire interface between the separator and the electrode.

Description

Technical Field

[0001] This disclosure relates to a coating rod and a method for manufacturing a partition using the coating rod.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0133531, filed in Korea on October 7, 2021, the disclosure of which is incorporated herein by reference. Background Technology

[0003] Rechargeable secondary batteries are gaining attention as an alternative to fossil fuels. They are primarily used in traditional handheld devices such as mobile phones, cameras, and power tools. However, recently, their applications have expanded to electrically powered vehicles (EVs, HEVs, PHEVs), high-capacity energy storage systems (ESS), and uninterruptible power systems (UPS).

[0004] A secondary battery includes: an electrode assembly comprising a positive electrode, a negative electrode, and a separator between the positive and negative electrodes; and an electrolyte that undergoes electrochemical and chemical reactions with active materials coated on the positive and negative electrodes. A typical example is a lithium-ion secondary battery, in which an electrochemical reaction occurs at the positive and negative electrodes during charging / discharging due to lithium ions acting as working ions. In existing lithium-ion secondary batteries, lamination is applied during the assembly process to ensure the adhesion strength between the electrodes and the separator in the electrode assembly. Lamination is the process of combining the separator and the electrodes. The lamination involves applying pressure and heat to the separator and electrodes stacked on top of each other to adhere them, thereby increasing the adhesion strength between the separator and the electrodes.

[0005] Typically, positive or negative electrodes are manufactured by coating an active material slurry onto a current collector and then drying the slurry. However, when the active material slurry is coated onto the current collector, a slippage phenomenon occurs as the slurry reaches both ends in the transverse direction. Therefore, the resulting active material layer has a relatively small thickness as it reaches both ends in the transverse direction.

[0006] Regarding this point, Figure 1 This illustrates a common electrode-separator stack structure. From Figure 1As can be seen, the separator 1 includes a porous coating 12 of uniform thickness on at least one surface of the porous polymer substrate 11, and the electrode 2 includes an active material layer 22 on at least one surface of the current collector 21. The thickness of the active material layer 22 gradually decreases as it extends laterally to both ends. Therefore, due to the insufficient thickness of the electrode at both ends in the lateral direction, the adhesion strength is low, particularly at the two ends, despite the lamination of the separator and the electrode. In more severe cases, adhesion failure occurs between the separator and the electrode.

[0007] Meanwhile, known methods for forming coatings by applying different materials to a substrate include, for example, gravure coating, reverse roll coating, and wire rod coating. Among these methods, wire rod coating is easier to operate and manage than other coating methods, and it achieves thin and uniform coating over large areas, thus making it widely used. Specifically, a wire rod coating method may include supplying a coating solution to a coating rod on which wire is wound, bringing the substrate and the coating rod into contact with each other and transferring the coating solution onto the substrate while rotating the coating rod, or applying the coating solution to a surface of the substrate and rotating the coating rod on which wire is wound.

[0008] However, since the coating formed using a coating bar is of uniform thickness, the wire bar coating method cannot form coatings with different thicknesses in a single coating operation. Summary of the Invention

[0009] Technical issues

[0010] This disclosure is designed to address the aforementioned problems; therefore, it relates to providing a predetermined coating rod for forming regions of different thicknesses through a single coating process. Furthermore, this disclosure also relates to a method for manufacturing a separator using said predetermined coating rod.

[0011] It will be apparent that these and other objects and advantages of this disclosure can be achieved by the means or methods set forth in the appended claims, and combinations thereof.

[0012] Technical solution

[0013] The inventors have discovered that the above-mentioned problems can be solved by the coating rod described below and the method of manufacturing a partition using the coating rod.

[0014] The first embodiment relates to a coating rod for coating an organic / inorganic paste onto a surface of a substrate, wherein the coating rod comprises a cylindrical rod and wires wound around the surface of the cylindrical rod, the diameter of the cylindrical rod at both ends being smaller than the diameter at the center, and the wire diameter of the wires wound at both ends being larger than the wire diameter of the wires wound at the center.

[0015] The second embodiment relates to a coating rod according to the first embodiment, wherein the outer diameter of the coating rod is uniform.

[0016] The third embodiment relates to a coating rod according to the first or second embodiment, wherein the length of one of its ends is 0.1%-10% of the total length of the coating rod.

[0017] The fourth embodiment relates to a coating rod according to any one of the first to third embodiments, wherein the wire diameter of the wire wound at both ends is 10% to 100% larger than the wire diameter of the wire wound at the center.

[0018] The fifth embodiment relates to a method for manufacturing a separator, comprising: preparing a porous polymer substrate; and coating at least one surface of the porous polymer substrate with an organic / inorganic slurry comprising an adhesive polymer and inorganic particles using a coating rod according to any one of the first to fourth embodiments to form a porous coating.

[0019] The sixth embodiment relates to a method for manufacturing a partition according to the fifth embodiment, wherein the thickness of the porous coating at both ends in the transverse direction is greater than the thickness at the center in the transverse direction.

[0020] The seventh embodiment relates to a method for manufacturing a partition according to the fifth or sixth embodiment, wherein the thickness of the porous coating at both ends in the transverse direction is 10% to 150% greater than the thickness at the center in the transverse direction.

[0021] The eighth embodiment relates to a method for manufacturing a partition according to any one of the fifth to seventh embodiments, wherein the length of one of the two ends of the porous coating is 0.1% to 10% of the total length of the partition in the width direction.

[0022] Beneficial effects

[0023] The coating bar according to this disclosure can form a coating with different thicknesses in a single coating process.

[0024] Furthermore, the method for manufacturing a separator according to this disclosure includes forming a porous coating using the predetermined coating rod to manufacture a separator comprising regions with porous coatings of varying thicknesses. Specifically, this disclosure can manufacture a separator having a greater thickness at both ends than at the center, thereby avoiding insufficient adhesion strength at both ends in the lateral direction during adhesion between the separator and the electrode, and exhibiting uniform adhesion strength across the entire interface between the separator and the electrode. Attached Figure Description

[0025] The accompanying drawings illustrate exemplary embodiments of this disclosure and, together with the foregoing description of this disclosure, are intended to aid in a further understanding of the technical aspects of this disclosure; therefore, this disclosure should not be construed as limited to the drawings. Furthermore, the shape, size, scale, or proportion of elements in the accompanying drawings may be exaggerated to emphasize a clearer description.

[0026] Figure 1 This is a schematic cross-sectional view showing a separator-electrode stack structure according to the prior art.

[0027] Figure 2 This is a schematic cross-sectional view showing the structure of the coating rod according to the present disclosure.

[0028] Figure 3 This is a schematic cross-sectional view showing the structure of the cylindrical rod included in the coating rod according to the present disclosure.

[0029] Figure 4 This is a schematic cross-sectional view illustrating an example of a stacked structure of electrodes and separators manufactured according to this disclosure. Detailed Implementation

[0030] The present disclosure will be described in detail below. It should be understood that the terms or words used in the specification and the appended claims should not be construed as limited to their common or dictionary meanings, but rather interpreted based on their meaning and concepts in relation to the technical aspects of the present disclosure, on the basis of allowing the inventors to appropriately define the terms for the best interpretation.

[0031] When used in this specification, the terms “comprising” or “including” specify 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.

[0032] The term “about” is used herein in the sense of being equal to or nearly equal to the manufacturing and material tolerances inherent in the given circumstances, and is used to prevent unethical infringers from improperly exploiting this disclosure, wherein precise or absolute figures are expressed in order to aid in the understanding of this disclosure.

[0033] Throughout this specification, A and / or B refers to A or B or both.

[0034] This disclosure relates to a coating rod and a method for manufacturing a partition using the coating rod. A detailed description will be provided below.

[0035] Coating rod

[0036] According to one aspect of this disclosure, the coating rod of this disclosure is a coating rod used for coating an organic / inorganic paste onto one surface of a substrate.

[0037] The coating rod comprises a cylindrical rod and wire wound around the surface of the cylindrical rod, wherein the diameter of the cylindrical rod at both ends is smaller than the diameter at the center, and

[0038] The wire diameter at both ends is greater than the wire diameter at the center.

[0039] The coating bar of this disclosure is used to coat an organic / inorganic slurry on one surface of a substrate, and the coating bar includes a cylindrical bar and wires wound around the surface of the cylindrical bar.

[0040] The substrate can include, but is not limited to, films, sheets, and nonwoven fabrics made of any material that can be used as a support. For example, the substrate can be a porous polymer substrate that can be used as a separator in a secondary battery. A porous polymer substrate is a substrate with multiple pores that act as an ion conduction barrier to block electrical contact between the negative and positive electrodes and allow ions to pass through. Porous polymer substrates can be made of polyolefin polymers such as polyethylene, polypropylene, and polybutene.

[0041] Organic / inorganic pastes are pastes that can be coated on at least one surface of a substrate and may include organic compounds and / or inorganic substances, and the components included in the paste are not limited to a particular type.

[0042] A typical coating rod is formed by winding wires of uniform diameter around a cylindrical rod of uniform diameter. During coating using this coating rod, a coating of uniform thickness can be formed on one surface of a substrate when the coating solution is contained in the space between adjacent wires.

[0043] However, while coating with a standard coating bar can create a uniform coating over a wide area, it can only create a coating with a uniform thickness, not a coating with areas of varying thickness.

[0044] Therefore, the inventors aim to provide a coating bar for forming regions of different thicknesses by a single coating process by modifying the design of the coating bar.

[0045] According to embodiments of the present disclosure, the diameter of the cylindrical rod of the coating rod of the present disclosure is smaller at both ends than at the center, and the wire diameter of the wire wound at both ends is larger than the wire diameter of the wire wound at the center.

[0046] When at least two types of wires with different diameters are wound onto a cylindrical rod with a uniform diameter, the region on which the wire with the larger diameter (i.e., the thicker wire) is wound has a larger outer diameter than the region on which the wire with the smaller diameter (i.e., the thinner wire) is wound. In this case, the wire in the region with the larger outer diameter exerts higher pressure on the substrate, causing the substrate to deform.

[0047] Therefore, this disclosure sets the diameter of the cylindrical bar on which the wire with a larger diameter is wound to be smaller than the diameter of the cylindrical bar on which the wire with a smaller diameter is wound, so that the pressure applied to the substrate by the coating bar is uniform.

[0048] Furthermore, the thickness of the organic / inorganic paste coated on the substrate can be adjusted by changing the diameter of the wires wound around the ends and center of the cylindrical rod. Specifically, according to the present disclosure, the amount of organic / inorganic paste contained in the space between adjacent wires wound around the ends of the cylindrical rod is greater than the amount of organic / inorganic paste contained in the space between adjacent wires wound around the center of the cylindrical rod. Therefore, a larger amount of organic / inorganic paste can be coated at the ends of the substrate than at the center, and a thicker coating can be formed at the ends of the substrate than at the center.

[0049] In particular, this disclosure modifies the design of the two ends of the coating rod. In this disclosure, the coating rod may include a center and ends, and the areas other than the center may be referred to as the two ends. Specifically, the length of one of the ends may be about 0.1% to 10% or about 0.2% to 5% of the total length of the coating rod.

[0050] According to specific embodiments of this disclosure, the outer diameter of the coating rod can be substantially uniform.

[0051] The outer diameter of the coating rod refers to the outer diameter of the coating rod measured at the location where the wire is wound. That is, the outer diameter of the coating rod corresponds to twice the sum of the radius of the cylindrical rod and the wire diameter. Furthermore, "consistent outer diameter" means that the outer diameter of the coating rod is consistent at both ends and the center, or that the outer diameters of the coating rod at both ends and the center are substantially equal, or that the outer diameters of the coating rod at both ends and the center are substantially equal within the measurement error range. Specifically, the diameter of the cylindrical rod at both ends and the wire diameter of the coating rod in this disclosure may be different, but the outer diameter of the coating rod can be consistent. That is, the diameter of the cylindrical rod can be larger at the center and smaller at both ends, and correspondingly, the wire diameter wound at the two ends of the cylindrical rod can be larger than the wire diameter wound at the center of the cylindrical rod.

[0052] Figure 2 The structure of a coating rod according to an embodiment of this disclosure is schematically shown. Furthermore, Figure 3 A cylindrical rod of a coating bar according to an embodiment of the present disclosure is schematically shown. Figure 2 It shows including wrapping in according to Figure 3 The cylindrical rod 31 is coated with wire 32 and the rod 30 has a larger wire diameter wound at both ends B1 and B2, and a smaller wire diameter wound at the center A, so that the outer diameter is consistent.

[0053] Furthermore, according to a specific embodiment of this disclosure, the wire diameter of the wire wound at both ends can be approximately 10% to 100% or 20% to 80% larger than the wire diameter wound at the center. When the difference between the wire diameters of the wires wound at the center and ends of the cylindrical rod corresponds to the above range, the thickness of the organic / inorganic paste coated at both ends and the center of the substrate can be adjusted within an optimal range.

[0054] Furthermore, according to specific embodiments of this disclosure, in this disclosure, the diameter of the cylindrical rod at both ends is smaller than its diameter at the center, and the diameter of the cylindrical rod at both ends can be determined based on the thickness of the wire wound around the ends. Specifically, for a uniform outer diameter of the coating rod, the diameter of the cylindrical rod at both ends and the center can be determined based on the thickness of the wire. For example, the diameter at both ends of the cylindrical rod can be approximately 0.5% to 10%, or 1% to 5%, smaller than the diameter at the center. When the difference in diameter between the two ends and the center of the cylindrical rod corresponds to the above range, the pressure applied to the substrate by the coating rod can be minimized when coating an organic / inorganic paste on one surface of the substrate, thereby preventing substrate deformation.

[0055] Method for manufacturing partitions

[0056] According to one aspect of this disclosure, a method for manufacturing a partition includes:

[0057] Preparation of porous polymer substrates; and

[0058] Using the coating bar according to an embodiment of this disclosure, an organic / inorganic slurry comprising a binder polymer and inorganic particles is coated on at least one surface of the porous polymer substrate to form a porous coating.

[0059] Specifically, in this disclosure, when forming the porous coating, the thickness at both ends of the porous coating can be adjusted by applying an organic / inorganic slurry to at least one surface of the porous polymer substrate using a coating bar according to an embodiment of this disclosure as described above. Specifically, after supplying the organic / inorganic slurry to the coating bar according to an embodiment of this disclosure, the organic / inorganic slurry can be transferred onto the porous polymer substrate while rotating the coating bar in contact with one surface of the porous polymer substrate to form a porous coating on one surface of the porous polymer substrate. Alternatively, after applying the organic / inorganic slurry to at least one surface of the porous polymer substrate, the organic / inorganic slurry can be applied while the coating bar according to an embodiment of this disclosure rotates over the organic / inorganic slurry, and the polymer substrate moves along the coating direction to form a porous coating on one surface of the porous polymer substrate.

[0060] The separator manufactured by conventional manufacturing methods has insufficient adhesion strength to the electrode due to insufficient adhesion strength at both ends. However, this disclosure provides a method for manufacturing the separator, which includes selectively increasing the thickness of the porous coating only at both ends, thereby solving the problem of insufficient adhesion strength at both ends and ensuring sufficient adhesion strength in the lamination of the separator and the electrode.

[0061] When the amount of adhesive polymer is increased or a separate adhesive layer is formed to ensure the adhesion strength between the separator and the electrode, the resistance of the battery cell increases or the thickness of the separator increases, resulting in capacity loss of the battery cell. However, the porous coating of the separator in this disclosure has a greater thickness at both ends in the lateral direction than at the center in the lateral direction, thereby avoiding capacity loss of the secondary battery.

[0062] According to specific implementations of this disclosure, such as Figure 4 As shown, the thickness of the porous coating at both ends in the transverse direction can be greater than the thickness at the center in the transverse direction.

[0063] For example, the thickness of the porous coating at both ends in the lateral direction can be approximately 10% to 150% or approximately 30% to 80% greater than the thickness at the center in the lateral direction. Alternatively, the ends of the porous coating in the lateral direction may include regions where its thickness gradually increases along a direction away from the center in the lateral direction. This disclosure sets the thickness of the porous coating at both ends in the lateral direction to be greater than the thickness at the center in the lateral direction, thereby solving the problem of insufficient adhesion strength at the ends in the lateral direction and ensuring sufficient adhesion strength in the lamination of the separator and electrode.

[0064] According to specific embodiments of this disclosure, the length of one of the ends of the porous coating can be about 0.1% to 10% or about 0.2% to 5% of the total length of the substrate in the width direction. When the end is set to a length within the above range, it can prevent a decrease in adhesion strength with the electrode and exhibit uniform adhesion strength across the entire interface between the electrode and the separator.

[0065] In this disclosure, a porous polymer substrate refers to a substrate having a plurality of pores as described above. The pores are interconnected to allow gas or liquid to pass through the substrate from one surface to another. From the perspective of a shutdown function, the porous polymer substrate may comprise a porous polymer film containing a thermoplastic resin. Here, the shutdown function refers to the function of preventing thermal runaway of the battery by closing the pores of the porous substrate to block ion movement when the thermoplastic resin melts as the battery temperature rises. For the shutdown function, the melting point of the thermoplastic resin is preferably less than about 200°C.

[0066] The porous polymer substrate is not limited to a specific thickness, but specifically, the thickness of the porous polymer substrate is about 1 μm to 100 μm, and more specifically, about 5 μm to 50 μm or about 5 μm to 30 μm, and the porous polymer substrate is not limited to a specific porosity, but the porosity of the porous polymer substrate is preferably about 10% to 95% or about 35% to 65%.

[0067] In this disclosure, inorganic particles are stacked in contact with each other and held together by a binder polymer within a porous coating to form interstitial volumes between the inorganic particles, thereby defining the void space for forming pores.

[0068] In addition, specifically in this disclosure, the weight ratio of inorganic particles to binder polymer in the porous coating can be from 99:1 to 50:50.

[0069] In this disclosure, the adhesive polymer is not limited to a specific type and may include any type of adhesive polymer capable of providing bonding strength between inorganic particles and bonding strength between the porous coating and the electrode. For example, the adhesive polymer may include at least one selected from the group consisting of: 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 n-propyl acrylate, poly(meth)acrylate isopropyl acrylate, poly(meth)acrylate n-butyl acrylate, poly(meth)acrylate tert-butyl acrylate, poly(meth)acrylate sec-butyl acrylate, poly(meth)acrylate pentyl acrylate, poly(meth)acrylate 2-ethylbutyl acrylate, poly(meth)acrylate 2-ethylhexyl acrylate, poly(meth)acrylate n-octyl acrylate, poly(meth)acrylate isooctyl acrylate, poly(meth)acrylate isononyl acrylate, poly(meth)acrylate dodecyl acrylate, poly(meth)acrylate tetradecyl acrylate, poly(N-vinylpyrrolidone), polyacrylonitrile, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate. Propionate, cyanoethyl pullullan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullullan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, and polyimide.

[0070] In addition, the binder polymer can be a particulate binder polymer resin, such as at least one of an acrylic copolymer or a styrene-butadiene rubber. The acrylic copolymer can include at least one of ethylhexyl acrylate-co-methyl methacrylate, polymethyl methacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, or butyl acrylate-co-methyl methacrylate.

[0071] In the present disclosure, the inorganic particles are not limited to a specific type and can include electrochemically stable inorganic particles. For example, the inorganic particles are not limited to a specific type and can include any type of inorganic particles that do not cause oxidation and / or reduction reactions within the operating voltage range of the electrochemical device being used (e.g., relative to Li / Li + from 0 to 5 V), and non-limiting examples of the inorganic particles can include at least one of ZrO2, BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT), PB(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnium oxide (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, AlOOH, Al(OH)3, or SiC. In addition to the above, the inorganic particles can also 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 (glass) (0 < x < 4, 0 < y < 13), 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), lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), SiS2-based glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), or P2S5-based glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7) or at least one of them.

[0072] Hereinafter, the present disclosure will be described in detail by way of examples. However, the embodiments of the present disclosure can be modified in many other forms, and the scope of the present disclosure should not be construed as being limited to the following examples. The embodiments of the present disclosure are provided to fully explain the present disclosure to those skilled in the art with ordinary knowledge in the technical field to which the present disclosure pertains.

[0073] Examples

[0074] The following methods are used to prepare each example and comparative example.

[0075] Hereinafter, reference will be made to Figure 2 as well as Tables 1 and 2 to describe the examples and comparative examples.

[0076] Example 1

[0077] Prepare a polyethylene porous substrate (thickness: 9 μm, porosity: 45%). Add polyvinylidene fluoride as an adhesive polymer and alumina (Al2O3) (particle size: 500 nm) as inorganic particles to acetone as a solvent to prepare a slurry.

[0078] Use a coating rod to coat the slurry on one surface of the porous substrate and dry it to manufacture a separator.

[0079] In this case, the coating rod used has the structure as <m Figure 2 shown. The total length of the coating rod is 250 mm, the center (A) is 200 mm, and each of the two ends (B1 and B2) is 25 mm. The outer diameter of the coating rod used is consistent. The diameter of the cylindrical rod at the center (A) is 12.7 mm, the wire diameter of the wire wound around the cylindrical rod at the center (A) is 0.4 mm, the diameter of the cylindrical rod at the two ends (B1 and B2) is 12.5 mm, and the wire diameter of the wire wound around the cylindrical rod at the two ends (B1 and B2) is 0.5 mm.

[0080] Example 2 and Comparative Examples 1 and 2

[0081] The partition was manufactured using the same method as in Example 1, and the slurry was coated by varying the diameter of the cylindrical rod at the center (A) and both ends (B1 and B2) of the coating rod, as shown in Table 1 below.

[0082] Table 1

[0083]

[0084] Table 2

[0085] Electrode adhesion strength (location A) Electrode adhesion strength (positions B1 and B2) Example 1 62gf / 25mm 59gf / 25mm Example 2 59gf / 25mm 67gf / 25mm Comparative Example 1 65gf / 25mm 11gf / 25mm Comparative Example 2 78gf / 25mm 17gf / 25mm

[0086] Specifically, the electrode adhesion strength (Lami strength, gf / 25mm) was evaluated using the following method. The active material [natural graphite and artificial graphite (weight ratio 5:5)], the conductive material [super P], and the binder [polyvinylidene fluoride (PVdF)] were mixed in a weight ratio of 92:2:6, dispersed in water, and coated onto a copper foil with a width of 250mm to create the negative electrode.

[0087] The partition with a width of 250 mm was prepared as in Examples 1 to 2 and Comparative Examples 1 to 2.

[0088] The prepared separator and negative electrode were stacked and inserted between 100 μm thick PET films and adhered using a roller laminator. In this case, the roller laminator conditions included adhesion at 60°C, a pressure of 2.4 kgf / mm, and a rate of 5 m / min.

[0089] The separator and negative electrode, which are attached to each other, are cut to a width of 25 mm at the center (A) and at both ends (B1 and B2) and a length of 70 mm. The ends of the separator and negative electrode are mounted on a UTM device (Instron), and a force of 180° is applied at a measurement rate of 300 mm / min to measure the force required to separate the negative electrode from the separator attached to it.

[0090] [Explanation of reference numerals in the attached figures]

[0091] 1: Partition

[0092] 11: Porous polymer substrate

[0093] 12: Porous coating

[0094] 2: Electrode

[0095] 21: Current collector

[0096] 22: Active material layer

[0097] 30: Coating rod

[0098] 31: Cylindrical rod

[0099] 32: Wire

[0100] A: Center

[0101] B1, B2: Ends

Claims

1. A coating rod for coating an organic / inorganic paste onto one surface of a substrate, wherein the coating rod comprises a cylindrical rod and wires wound around the surface of the cylindrical rod. The diameter of the cylindrical rod at both ends is smaller than its diameter at the center, and The diameter of the wire wound at both ends is greater than the diameter of the wire wound at the center.

2. The coating rod according to claim 1, wherein the outer diameter of the coating rod is uniform.

3. The coating rod according to claim 1, wherein the length of one of the two ends is 0.1%-10% of the total length of the coating rod.

4. The coating rod according to claim 1, wherein the diameter of the wire wound at both ends is 10% to 100% larger than the diameter of the wire wound at the center.

5. The coating rod according to claim 1, wherein the substrate is a porous polymer substrate, the porous polymer substrate being used as a substrate for a separator in a secondary battery.

6. The coating rod of claim 1, wherein the amount of the organic / inorganic slurry contained in the space between adjacent wires wound at the two ends of the cylindrical rod is greater than the amount of the organic / inorganic slurry contained in the space between adjacent wires wound at the center of the cylindrical rod.

7. The coating rod according to claim 2, wherein the outer diameter of the coating rod corresponds to twice the sum of the radius of the cylindrical rod and the diameter of the wire.

8. The coating rod according to claim 4, wherein the diameter of the wire wound at the two ends is 20% to 80% larger than the diameter of the wire wound at the center.

9. The coating rod according to claim 1, wherein the diameter of the cylindrical rod at both ends is 0.5% to 10% smaller than the diameter at the center.

10. The coating rod of claim 9, wherein the diameter of the cylindrical rod at both ends is 1% to 5% smaller than the diameter at the center.

11. A method for manufacturing a partition, comprising: Preparation of porous polymer substrates; and An organic / inorganic slurry comprising a binder polymer and inorganic particles is applied to at least one surface of the porous polymer substrate using a coating rod according to any one of claims 1 to 10 to form a porous coating.

12. The method for manufacturing a partition according to claim 11, wherein the thickness of the porous coating at both ends in the transverse direction is greater than the thickness at the center in the transverse direction.

13. The method for manufacturing a partition according to claim 11, wherein the thickness of the porous coating at both ends in the transverse direction is 10% to 150% greater than the thickness at the center in the transverse direction.

14. The method for manufacturing a partition according to claim 11, wherein the length of one of the two ends of the porous coating is 0.1%-10% of the total length of the partition in the width direction.

15. The method for manufacturing a partition according to claim 13, wherein the thickness of the porous coating at both ends in the transverse direction is 30% to 80% greater than the thickness at the center in the transverse direction.

16. The method for manufacturing a separator according to claim 11, wherein the weight ratio of the inorganic particles and the binder polymer in the porous coating is from 99:1 to 50:50.

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