KR20190127146A - Secondary battery including porous substrate having coating layer - Google Patents

Abstract

According to an embodiment of the present invention, disclosed is a secondary battery which includes: an anode member; a cathode member; a porous substrate disposed between the anode member and the cathode member to physically separate the anode member and the cathode member; and a coating layer formed on at least one surface of the porous substrate in a state where at least one of a plurality of ceramic particles and a fixing member is included wherein the coating layer is formed as a designated area of an edge region of at least one surface of the porous substrate. Aside from this, various embodiments understood through the specification are possible.

Description

Secondary battery including a porous substrate having a coating layer formed {Secondary battery including porous substrate having coating layer}

Various embodiments disclosed herein relate to improving stability of a secondary battery separator.

Recently, as the spread of electronic devices equipped with proprietary operating systems is rapidly spreading, electronic devices provide various functions aimed at user convenience or interaction with users. Accordingly, the importance of a secondary battery, which is a pivotal basis for the function operation of the electronic device, has been highlighted.

Secondary batteries are a power source for supplying electrical energy by chemical reactions. In addition to the primary advantage of reducing the use of fossil fuels, there are no product by-products, including electronic devices. : It is applied to electric vehicles.

The separator (or separator) included in the secondary battery isolates the positive electrode and the negative electrode to block mutual contact, and also functions as a medium for ion conduction to support charging or discharging of the secondary battery. However, when the secondary battery is transitioned to a thermal runaway state (eg, a sudden rise in the internal temperature of the secondary battery) due to an external shock or the like, the separator not only loses the above-described function but also causes physical shrinkage to cause the positive electrode and It can cause internal short circuit between the cathodes.

Various embodiments disclosed in the present disclosure provide a secondary battery including a porous substrate on which a coating layer is formed, which may improve thermal or mechanical properties, based on an improvement in a composition of a coating layer included on at least one side of a separator. Can provide.

A secondary battery according to an embodiment may include a cathode substrate, a cathode member, a porous substrate disposed between the anode member and the cathode member to physically separate the anode member and the cathode member. , And a coating layer formed on at least one surface of the porous substrate in a state including at least one of a plurality of ceramic particles or a fixing member.

According to one embodiment, the coating layer may be formed of a designated region of the edge region of at least one surface of the porous substrate.

The porous substrate on which the coating layer is formed according to an embodiment may include a porous substrate and a coating layer formed on at least one surface of the porous substrate.

According to an embodiment, the coating layer may include 0 to 90 parts by weight of ceramic particles based on 100 parts by weight of the coating layer, and may include 0 to 10 parts by weight of a fixing member based on 100 parts by weight of the coating layer.

According to an embodiment, the fixing member may include 0 to 30 parts by weight of polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on 0 to 10 parts by weight, and 0 to 10 parts by weight. Meta-aramids may be included in an amount of 0 to 70 parts by weight based on parts.

According to various embodiments, by implementing a separator that is robust to the thermal runaway environment of the secondary battery to prevent internal short circuit between the positive electrode and the negative electrode, damage or degradation of the secondary battery may be suppressed, and operational stability may be improved.

In addition, various effects may be provided that are directly or indirectly identified through this document.

1 is a diagram illustrating at least a part of a secondary battery electrode assembly according to an exemplary embodiment.
2 is a view illustrating a shape of a secondary battery electrode assembly according to an exemplary embodiment.
3 is a view showing a coating layer arrangement on the porous substrate according to the first embodiment.
4 is a view showing a coating layer arrangement on the porous substrate according to the second embodiment.
5 is a view showing a coating layer arrangement on a porous substrate according to the third embodiment.
6 is a view showing a coating layer arrangement on a porous substrate according to a fourth embodiment.
In connection with the description of the drawings, the same reference numerals may be given to the same or corresponding components.

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. However, it is not intended to limit the present invention to specific embodiments, but it should be understood to include various modifications, equivalents, and / or alternatives of the embodiments of the present invention. In connection with the description of the drawings, similar reference numerals may be used for similar components.

In this document, expressions such as "have", "may have", "include", or "may contain" include the presence of a corresponding feature (e.g., numerical, functional, operational, or component such as a component). Does not exclude the presence of additional features.

In this document, expressions such as "A or B", "at least one of A or / and B", or "one or more of A or / and B" may include all possible combinations of items listed together. . For example, "A or B", "at least one of A and B", or "at least one of A or B" includes (1) at least one A, (2) at least one B, Or (3) both of cases including at least one A and at least one B.

Expressions such as "first," "second," "first," or "second," as used herein, may modify various components, regardless of order and / or importance, and may modify one component to another. It is used to distinguish a component and does not limit the components. For example, without departing from the scope of rights described in this document, the first component may be called a second component, and similarly, the second component may be renamed to the first component.

The expression "configured to" used in this document is, for example, "suitable for", "having the capacity to" depending on the situation. It may be used interchangeably with "designed to", "adapted to", "made to", or "capable of".

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. The terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the art. Among the terms used in this document, terms defined in the general dictionary may be interpreted as having the same or similar meaning as the meaning in the context of the related art, and unless it is clearly defined in this document, in an ideal or excessively formal meaning. Not interpreted. In some cases, even if terms are defined in the specification, they may not be interpreted to exclude embodiments of the present disclosure. Hereinafter, a battery according to various embodiments of the present disclosure will be described with reference to the accompanying drawings.

1 is a diagram illustrating at least a part of an electrode assembly according to an exemplary embodiment.

Referring to FIG. 1, a secondary battery (eg, a lithium ion secondary battery or a lithium ion polymer secondary battery, etc.) according to an embodiment may include an anode member 110 and a cathode. ) An electrode assembly 100 formed of a member 130 and a separator 150 (or a separator) disposed between the negative electrode member 110 and the positive electrode member 130. According to an embodiment, the electrode assembly 100 may include a jelly roll type electrode assembly in which the stacked structure of the cathode member 110, the separator 150, and the anode member 130 is spirally wound. At least one metal laminate sheet may be accommodated in a pouch-shaped, angular, cylindrical, or coin-type sheath formed by lamination.

In one embodiment, the negative electrode member 110 or the positive electrode member 130 is a current collector (for example, the negative electrode current collector 115 included in the negative electrode member 110 or the positive electrode current collector included in the positive electrode member 130 ( 135) may be formed by applying a slurry containing an active material, a solvent, a binder, and / or a conductive material to be dried, followed by a roll pressing and cutting process.

The current collector 115 of the negative electrode member 110 may include, for example, copper (Cu), gold (Au), nickel (Ni), a copper alloy, or a combination of two or more thereof. The current collector 135 of the positive electrode member 130 may include, for example, any one of aluminum (Al) and nickel (Ni), or may include a combination of aluminum and nickel.

The active material of the negative electrode member 110 may be, for example, a lithium metal, a lithium alloy, or a carbon material (for example, natural graphite, Kish graphite, pyrolytic carbon, and liquid crystal pitch based carbon fiber). fiber), carbon microspheres (meso-carbon microbeads), liquid crystal pitches (Mesophase pitches), or petroleum or coal-based coke (petroleum or coal tar pitch derived cokes, etc.) and the like. The active material of the positive electrode member 130 may be, for example, a lithium metal oxide such as LiCoO 2, LiNiO 2 or LiMn 2 O 4, or LiNi 1-x CoxO 2 or LiNixCoyMnzO 2 to which cobalt (Co), nickel (Ni), or manganese (Mn) is added , LiNiMnO 2 or Li 2 MnO 3, and the like.

The solvent is, for example, N-methyl-2-pyrrolidone (N-methyl-2-pyrolydone), diacetone alcohol, dimethyl formaldehyde (dimethyl formaldehyde), propylene glycol monomethyl ether ), Methyl cellosolve, ethyl cellosolve, butyl cellosolve, isopropyl cellosolve, acetylacetone, methylisobutylketone, n It may include any one of -butyl acetate (n-butyl acetate), cellosolve acetate toluene or xylene, or may include a combination of two or more of the above-described materials.

The binder may be, for example, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride trichloroethylene, polymethylmethacrylate, polybutyl acrylate (polybutylacrylate), polyarylate, ethylene vinyl co-vinyl acetate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate propionate, carboxyl methyl cellulose, pullulan, polyvinylacetate, cyanoethylpullulan, polyvinylpyrrolidone, polyethyleneoxide, Cyanoethylpolyvinylal It may include at least one of cyanoethylpolyvinylalcohol, cyanoethylcellulose, or cyanoethyl sucrose, and may promote binding between the active material, the solvent, and / or the conductive material.

The conductive material may be, for example, acetylene black, carbon black, denka black, carbon fiber, carbon nanotube, metal powder or conductive metal. It may include at least one of conductive metal oxides.

According to various embodiments of the present disclosure, materials for implementing the current collector 115 of the negative electrode member 110, the current collector 135 of the positive electrode member 130, an active material, a solvent, a binder, or a conductive material are limited as described above. It may not include a variety of materials used in conventional secondary battery manufacture.

In one embodiment, the separator 150 blocks physical contact between the positive electrode member 110 and the negative electrode member 130, and at the same time, ions between the positive electrode member 110 and the negative electrode member 130 when the secondary battery is charged or discharged. Can support evangelism. In this regard, the separator 150 is included in at least one surface of the porous substrate 151 and the porous substrate 151 for conducting the ions to improve the thermal or mechanical properties of the separator 150, 153 It may include. According to various embodiments, the coating layer 153 is formed of a separate layer (coating) on at least one side of the porous substrate 151, or the porous substrate as the same layer as the porous substrate 151 151 may be included as at least part of itself.

The porous substrate 151 may include, for example, a polyolefin based porous membrane (or porous film), and the porous membrane may be polymethyl pentene, polypentene, polyethylene (polyethylene), polybutylene (polybutylene), polypropylene (polypropylene) or a combination of two or more thereof may be singly or laminated. Alternatively, the porous substrate 151 may be polyolefin-based, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, or polycarbonate. , Polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfidro, polyethylenenaphthalene or two or more thereof Combinations of nonwovens.

In various embodiments, the porous substrate 151 may have a specific melting point (eg, about 110 ° C. to 160 ° C.) according to the characteristics of the material to be manufactured. In this regard, the porous substrate 151 may be melted when the internal temperature of the secondary battery rises to reach the specific melting point, thereby losing the porous structure, and may block ion conduction between the negative electrode member 110 and the positive electrode member 130. have.

The coating layer 153 may include at least one of a thermally or mechanically stable polymer 10 (hereinafter, abbreviated as a polymer) or inorganic particles 20 in a designated weight part. For example, the coating layer 153 may include ceramic particles as 0 to 90 parts by weight based on 100 parts by weight of the coating layer 153 as the inorganic particles 20, and the polymer 10 may include the coating layer 153. It may include 0 to 10 parts by weight based on parts by weight. In one embodiment, the polymer 10 includes 0 to 30 parts by weight of polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on 0 to 10 parts by weight, and meta-type aramid (meta -aramids) can be included from 0 to 70 parts by weight. According to one embodiment, the polymer 10 including a combination of the polyparaphenylene benzobisoxazole and meta-type aramid is supported by the adhesion of the inorganic particles 20 and the porous substrate 151 to prevent the detachment phenomenon can do. In addition, the thermal or mechanical strength of the coating layer 153 may be improved due to the excellent tensile strength and heat resistance of the polyparaphenylene benzobisoxazole and the excellent elongation and endothermic properties of the meta-aramid.

In various embodiments, the coating layer 153 may be a dip coating, a die coating, a roll coating, a gravure coating, a spray coating, a comma coating, or a combination thereof. It may be coated on the porous substrate 151 based on the coating method used.

In an embodiment, at least one of the above-described negative electrode member 110, separator 150, or positive electrode member 130 may be impregnated with an organic electrolyte. The organic electrolyte may include an organic solvent and a lithium salt. The organic solvent may be, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl propyl carbonate, or dipropyl carbonate. carbonate, vinylene carbonate, fluorinated ethylene carbonate, vinylethylene carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, die Diethoxyethane, sulfolane, gamma-butyrolactone, propylene sulfite, tetrahydrofuran, ethyl propionate, propyl propionate Propyl propionate, methyl acetate, ethyl acetate or phthalate Of peel acetate (propyl acetate) may include at least one. In addition, the lithium salt is, for example, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), bisodium bifluoride (LiAsF6), lithium trifluoromethane sulfonate (LiCF3SO3), lithium bistry At least one of fluormethanesulfonylamide (LiN (CF 3 SO 2) 2) or lithium bisoxate (LiBOB).

2 is a view illustrating a shape of a secondary battery electrode assembly according to an exemplary embodiment.

Referring to FIG. 2, the electrode assembly 100 includes a negative electrode member 110 including a negative electrode current collector (115 of FIG. 1), a positive electrode member 130 including a positive electrode current collector (135 of FIG. 1), and a porous substrate. The separator 150 including 151 of FIG. 1 may include a jelly roll type electrode assembly stacked and wound in a predetermined order. According to an embodiment, an electrode tab 30 may be connected to a current collector 115 of the negative electrode member 110 or a region of the current collector 135 of the positive electrode member 130. 3, 4, 5, and 6, which are referred to below, illustrate shapes before winding of some components of the electrode assembly 100, for example, a current collector to which the electrode tab 30 is connected. Relative overlap between the 115 or 135 and the porous substrate 151.

3 is a view showing a coating layer arrangement on the porous substrate according to the first embodiment, Figure 4 is a view showing a coating layer arrangement on the porous substrate according to the second embodiment.

2, 3, and 4, the coating layer 153 coated on at least one side of the porous substrate 151 may be coated to a designated area on at least one side of the porous substrate 151. In this regard, one of the negative electrode current collector 115 (or the positive electrode current collector (135 in FIG. 1)) included in the negative electrode member 110 (or the positive electrode member 130) stacked with the porous substrate 151. An electrode tab 30 (eg, a negative electrode tab or a positive electrode tab) may be connected to the region. At least one region of the electrode tab 30 may be connected to an electrode lead of a conductive material, and the secondary battery may be electrically connected to a secondary battery or an external device based on the electrode lead. Accordingly, heat generation due to conductive may occur in the peripheral region of the electrode tab 30. In one embodiment, the coating layer 153 and the negative electrode current collector 115, the electrode tab 30 is included in the negative electrode member 110 to prevent thermal or mechanical damage of the porous substrate 151 by the heat generation It may be coated to cover the area to which it is connected. In other words, the coating layer 153 is at least partially connected to the connection region of the electrode tab 30 and the negative electrode member 110 (or the negative electrode current collector 115 included in the negative electrode member 110) on the porous substrate 151. It can be coated with overlapping areas.

Referring to FIG. 3 as an example, the coating layer 153 is formed on the left side of the porous substrate 151 based on a first direction in which the porous substrate 151 is laminated with the cathode member 110 and the anode member 130. It may be coated on at least one of the termination (or left edge) region 1 or the right termination region 2. As another example, referring to FIG. 4, the coating layer 153 may be coated on a region 3 having a designated area from the left end to the right end of the porous substrate 151 based on the first direction.

5 is a view showing a coating layer arrangement on the porous substrate according to the third embodiment, Figure 6 is a view showing a coating layer arrangement on the porous substrate according to the fourth embodiment.

2, 5, and 6, the coating layer 153 coated with the designated area (1 in FIG. 3, 2 in FIG. 3 or 3 in FIG. 4) on the above-described porous substrate 151 may be formed in the designated area ( It may also be coated in areas other than 1, 2 or 3). For example, referring to FIG. 5, a coating layer 153 includes a plurality of designated regions 1 and 2 on the porous substrate 151, and a plurality of designated regions 1 and 2 in the region between the plurality of designated regions 1 and 2. It may be coated with a pattern 40 extending parallel to the designated areas 1 and 2. For another example, referring to FIG. 6, the coating layer 153 is a direction in which the porous substrate 151 is wound from the region 3 of the designated area, including the region 3 of the designated area on the porous substrate 151. It may be coated with a pattern 50 extending to. According to one embodiment, the coating layer 153 coated by including the pattern 40 or 50 may improve the thermal or mechanical strength of the porous substrate 151.

According to various embodiments of the present disclosure, a secondary battery includes a negative electrode member, a positive electrode member, a porous substrate disposed between the negative electrode member and the positive electrode member to physically separate the negative electrode member and the positive electrode member, and a plurality of It may include a coating layer formed on at least one surface of the porous substrate in a state containing at least one of the ceramic particles or the fixing member.

According to various embodiments of the present disclosure, the coating layer may be formed as a designated region among edge regions of at least one surface of the porous substrate.

According to various embodiments of the present disclosure, the negative electrode member, the porous substrate, and the negative electrode member may be stacked and wound in a predetermined order.

According to various embodiments of the present disclosure, the coating layer may be formed on at least one region of the left edge region or the right edge region of the porous substrate based on the winding direction of the porous substrate. .

According to various embodiments of the present disclosure, the coating layer may be further formed in at least one pattern region parallel to the winding direction in a region between the left edge region and the right edge region of the porous substrate.

According to various embodiments of the present disclosure, the coating layer may be formed in a region having a designated area extending from a left edge region to a right edge region of the porous substrate.

According to various embodiments of the present disclosure, the coating layer may be further formed in at least one pattern region extending from the region of the designated area and parallel to the winding direction in an area other than the region of the designated area of the porous substrate. .

According to various embodiments of the present disclosure, the negative electrode member may include a first current collector, and the first current collector may include at least one of copper, gold, or nickel.

According to various embodiments of the present disclosure, the positive electrode member may include a second current collector, and the second current collector may include at least one of aluminum or nickel.

According to various embodiments of the present disclosure, an electrode tab may be connected to at least one region of the first current collector or the second current collector.

According to various embodiments of the present disclosure, the coating layer may be formed in a region overlapping at least a portion of the electrode tab among the edge regions.

According to various embodiments of the present disclosure, the porous substrate may include at least one of a polyolefin-based porous film or a polyolefin-based porous nonwoven fabric.

According to various embodiments of the present disclosure, the coating layer may include 0 to 90 parts by weight of the ceramic particles based on 100 parts by weight of the coating layer.

According to various embodiments of the present disclosure, the coating layer may include 0 to 10 parts by weight of the fixing member based on 100 parts by weight of the coating layer.

According to various embodiments of the present disclosure, the fixing member may include 0 to 30 parts by weight of polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on the amount of 0 to 10 parts by weight.

According to various embodiments of the present disclosure, the fixing member may include 0 to 70 parts by weight of meta-aramids based on the amount of 0 to 10 parts by weight.

The porous substrate on which the coating layer is formed according to various embodiments of the present disclosure may include a porous substrate and a coating layer formed on at least one surface of the porous substrate.

According to various embodiments of the present disclosure, the coating layer may include 0 to 90 parts by weight of ceramic particles based on 100 parts by weight of the coating layer, and may include 0 to 10 parts by weight of a fixing member based on 100 parts by weight of the coating layer.

According to various embodiments of the present disclosure, the fixing member may include 0 to 30 parts by weight of polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on 0 to 10 parts by weight, and 0 to 10 parts by weight. Meta-aramids may be included in an amount of 0 to 70 parts by weight based on parts.

According to various embodiments of the present disclosure, the coating layer may be formed on at least one region of the left edge region or the right edge region of the porous substrate based on the designated first direction.

According to various embodiments of the present disclosure, the coating layer may be further formed in at least one pattern region parallel to the designated first direction in a region between a left edge region and a right edge region of the porous substrate.

According to various embodiments of the present disclosure, the coating layer may be formed in a region having a designated area extending from a left edge region to a right edge region of the porous substrate.

According to various embodiments of the present disclosure, the coating layer may be further formed in at least one pattern region extending from the region of the designated area in a region other than the region of the designated area of the porous substrate and parallel to the designated first direction. have.

Various embodiments of the present document and terms used therein are not intended to limit the techniques described in this document to specific embodiments, but should be understood to include various modifications, equivalents, and / or substitutes of the embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar components. Singular expressions may include plural expressions unless the context clearly indicates otherwise. In this document, expressions such as "A or B", "at least one of A and / or B", "A, B or C" or "at least one of A, B and / or C", etc. Possible combinations may be included. Expressions such as "first," "second," "first," or "second," etc. may modify the components in any order or importance, and are only used to distinguish one component from another. It does not limit the components.

The embodiments disclosed in this document are presented for the purpose of explanation and understanding of the technical content, and do not limit the scope of the present invention. Accordingly, the scope of the present disclosure should be construed as including all changes or various other embodiments based on the technical spirit of the present disclosure.

Claims (20)

In a secondary battery,
An anode member;
A cathode member;
A porous substrate disposed between the negative electrode member and the positive electrode member to physically separate the negative electrode member and the positive electrode member; And
And a coating layer formed on at least one surface of the porous substrate in a state including at least one of a plurality of ceramic particles or a fixing member.
The coating layer,
The secondary battery is formed of a designated region of the edge region of at least one surface of the porous substrate. The method of claim 1,
The negative electrode member, the porous substrate and the negative electrode member,
A secondary battery that is stacked and wound in a designated sequence. The method of claim 2,
The coating layer,
The secondary battery of the edge region, the porous substrate is formed in at least one of the left edge region or the right edge region of the porous substrate with respect to the winding direction. The method of claim 3,
The coating layer,
In the region between the left edge region and the right edge region of the porous substrate, the secondary battery further formed in at least one pattern region parallel to the wound direction. The method of claim 3,
The coating layer,
And a secondary battery formed in a region of a designated area extending from a left edge region to a right edge region of the porous substrate. The method of claim 5,
The coating layer,
In a region other than the region of the designated area of the porous substrate, further formed in at least one pattern region extending from the region of the designated area and parallel to the wound direction. The method of claim 1,
The negative electrode member,
Including a first current collector,
The first current collector,
A secondary battery comprising at least one of copper, gold or nickel. The method of claim 7, wherein
The anode member,
Including a second current collector,
The second current collector,
A secondary battery comprising at least one of aluminum or nickel. The method of claim 8,
An electrode tab is connected to at least one region of the first current collector or the second current collector. The method of claim 5,
The coating layer,
A secondary battery, formed in a region overlapping at least a portion of the electrode tab among the edge regions. The method of claim 1,
The porous substrate,
A secondary battery comprising at least one of a polyolefin-based porous film or a polyolefin-based porous nonwoven fabric. The method of claim 1,
The coating layer,
A secondary battery comprising 0 to 90 parts by weight of the ceramic particles based on 100 parts by weight of the coating layer. The method of claim 1,
The coating layer,
A secondary battery comprising 0 to 10 parts by weight of the fixing member based on 100 parts by weight of the coating layer. The method of claim 13,
The fixing member,
A secondary battery comprising 0 to 30 parts by weight of polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on 0 to 10 parts by weight. The method of claim 13,
The fixing member,
A secondary battery comprising 0 to 70 parts by weight of meta-aramids based on 0 to 10 parts by weight. Porous substrates; And
And a coating layer formed on at least one surface of the porous substrate.
The coating layer,
On the basis of 100 parts by weight of the coating layer comprises 0 to 90 parts by weight of ceramic particles, based on 100 parts by weight of the coating layer comprises 0 to 10 parts by weight of the fixing member,
The fixing member,
Polyparaphenylene benzobisoxazole (poly (p-phenylene benzobisoxazole)) based on 0 to 10 parts by weight of 0 to 30 parts by weight, meta-aramids based on 0 to 10 parts by weight Containing 0 to 70 parts by weight, a porous substrate with a coating layer formed. The method of claim 16,
The coating layer,
A porous substrate having a coating layer formed on at least one of a left edge region or a right edge region of the porous substrate with respect to the designated first direction. The method of claim 17,
The coating layer,
And a coating layer further formed in at least one pattern region parallel to the designated first direction in a region between the left edge region and the right edge region of the porous substrate. The method of claim 17,
The coating layer,
A porous substrate having a coating layer formed on a region of a designated area extending from a left edge region to a right edge region of the porous substrate. The method of claim 19,
The coating layer,
And a coating layer further formed in at least one pattern region extending from the region of the designated area and parallel to the designated first direction in a region other than the region of the designated area of the porous substrate.

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