A separator and an electrochemical device including the separator

Abstract

The present disclosure relates to a separator and an electrochemical device comprising said separator. The present embodiment provides a separator comprising: a porous substrate; an inorganic particle layer disposed on at least one surface of said porous substrate and comprising inorganic particles; and an adhesive layer disposed on said inorganic particle layer and comprising organic particles in the shape of secondary particles.

Description

Technology Field

[0001] The present disclosure relates to a separator and an electrochemical device comprising said separator. Specifically, it relates to a separator having excellent electrode adhesion, anti-blocking properties, and breathability, and an electrochemical device comprising said separator. Background Technology

[0002] To address the high-temperature stability issues of separators, ceramic-coated separators (CCS) in which a layer of porous inorganic particles is formed on one or both sides of a porous substrate have been conventionally used. These ceramic-coated separators have the advantage of excellent heat resistance due to their low high-temperature thermal shrinkage rate, and are therefore applied to large battery systems for EVs.

[0003] However, conventional ceramic-coated separators often lack sufficient adhesion to the electrodes, leading to separation between the separator and the electrode during the cell assembly process and resulting in warping or deformation of the electrode assembly. In other words, when the adhesion between the ceramic coating layer of the separator and the electrode is insufficient as described above, misalignment issues occur between the electrode and the separator within the jelly roll during cell stacking. When operating a stack cell with such misalignment, the occurrence of localized resistance due to the misalignment or physical damage from continuous use can lead to short circuits between the electrodes, posing safety risks such as fire.

[0004] Therefore, improving the adhesion between the ceramic-coated separator and the electrode is an issue that must be addressed for battery stability.

[0005] One method to improve the adhesion between the separator and the electrode is to form an adhesive organic layer on top of the inorganic particle layer of the ceramic-coated separator, but the organic layer causes poor air permeability, makes thin film formation difficult, results in poor electrode adhesion, and causes a blocking phenomenon in which the adhesive organic layer detaches during separator winding. Therefore, there are still problems to be solved, such as reduced ion conductivity of the separator or / and thickness variation occurring during alignment of the electrode assembly, which impairs the performance of the battery. Prior art literature

[0006] Japanese Registered Patent Publication No. 4414165 (Publication Date: March 3, 2005) The problem to be solved

[0007] To solve the aforementioned problems, one embodiment of the present disclosure aims to provide a separator having excellent electrode adhesion, anti-blocking properties, and breathability even at a thin thickness, and an electrochemical device including said separator.

[0008] In one embodiment, a separator can be provided in which the thickness of the adhesive layer is 2 μm or less and the total thickness of the separator is 20 μm or less and 15 μm or less, and the separator has excellent electrode adhesion, anti-blocking properties, and breathability even within the above range, and an electrochemical device including said separator can be provided. means of solving the problem

[0009] As a means for achieving the above-mentioned objective, the present disclosure provides a separation membrane comprising: a porous substrate; an inorganic particle layer disposed on at least one surface of the porous substrate, wherein inorganic particles are connected to each other to form pores between the inorganic particles; and an adhesive layer disposed on the inorganic particle layer, wherein organic particles having a plurality of protrusion parts and a plurality of valley parts are connected to each other to form pores.

[0010] In one embodiment, the ratio of the average particle size (D50) of the organic particle to the average particle size (D50) of the inorganic particle may be 0.5 to 1.5.

[0011] In one embodiment, the D50 of the organic particle may be 0.1 μm to 1.5 μm.

[0012] In one embodiment, regarding the particle size distribution of the organic particles, the D10 / D90 value may be 0.3 to 0.9.

[0013] In one embodiment, the glass transition temperature (Tg) of the organic particles may be 50 to 90°C.

[0014] In one embodiment, the thickness of the adhesive layer may be greater than 0㎛ and less than or equal to 2㎛.

[0015] In one embodiment, the organic particle may be a secondary particle in which a plurality of protrusion parts and a plurality of valley parts are formed by the aggregation of primary particles by surface melting, or a primary particle having a plurality of protrusion parts and a plurality of valley parts on its surface.

[0016] In one embodiment, the adhesive layer may contain at least 70% by weight of organic particles based on the total weight of the adhesive layer.

[0017] In one embodiment, the adhesive layer contains 0.2 to 2.0 g / m² of the organic particles 2 It can be included as.

[0018] In one embodiment, the separator may be laminated so that the adhesive layer of the separator faces a carbon sheet (TOYO Tanso Korea, PF-20HP) with a thickness of 200 μm, then bonded by pressing with a heat press at 80° and 20 MPa for 30 seconds, and then the electrode adhesion strength measured by peeling at 180° using an INSTRON UTM machine according to ASTM D 903 may be 1.5 gf / 15mm to 4.0 gf / 15mm.

[0019] In one embodiment, the separator may have a change in air permeability ΔG measured by the following formula of 50 sec / 100cc or less.

[0020] △G = G1- G2

[0021] In the above formula, G1 is the Gulli permeability of a separator in which an inorganic particle layer and an adhesive layer are sequentially laminated on both sides of a porous substrate, and G2 is the Gulli permeability of the porous substrate itself. The Gulli permeability is measured according to ASTM D 726 standards using a Toyoseiki Densometer, and the unit is sec / 100cc.

[0022] In one embodiment, the separator may be such that when two separators are arranged so that the adhesive layers face each other, then compressed at a temperature of 60°C and a pressure of 7.5 MPa for 1 hour, and then peeled off at 180 degrees according to ASTM D903, the adhesive layers do not adhere to each other and the phenomenon of partial or complete peeling does not occur, and the adhesive layers remain separated without blocking.

[0023] In addition, as another means for achieving the above-described objective, according to one embodiment of the present disclosure, an electrochemical device comprising a separator of the above-described embodiment is provided. Effects of the invention

[0024] The separator of the present disclosure can have excellent electrode adhesion, anti-blocking properties, or breathability even at a thin thickness.

[0025] In one embodiment, the separator is laminated so that the adhesive layer of the separator faces the carbon sheet with a thickness of 200 μm, then bonded by pressing with a heat press at 80° and 20 MPa for 30 seconds, and then peeled at 180° using a UTM machine according to ASTM D 903. The electrode adhesion strength measured may be 1.5 gf / 15 mm or more, 2.0 gf / 15 mm or more, 2.3 gf / 15 mm or more, 2.5 gf / 15 mm or more, or 3.0 gf / 15 mm or more. For example, it may be 1.5 gf / 15 mm to 4.0 gf / 15 mm. According to the above embodiment, sufficient electrode adhesion can be secured even when containing a relatively small amount of organic particles in the form of secondary particles formed by the melting and aggregation of the surface of primary particles of a polymer having a high glass transition temperature.

[0026] A separator of one embodiment can secure excellent electrode adhesion even at a thin thickness, while simultaneously having excellent anti-blocking properties. For example, two separators, each having a porous substrate, an inorganic particle layer, and an adhesive layer laminated thereon, are laminated and arranged so that the adhesive layers face each other, and then compressed for one hour at a temperature of 60°C and a pressure of 7.5 MPa. Then, when the bonded portion is peeled off and SEM is used to check whether the adhesive layer has partially or completely peeled off and caused blocking between the separator surfaces, the separator can have excellent anti-blocking performance in which blocking, a phenomenon in which the adhesive layer partially detaches from each other's separators, does not occur.

[0027] In one embodiment, the separator may have excellent air permeability even if it has a multilayer structure such as placing an adhesive layer on an inorganic particle layer, and the change in air permeability (△G) expressed by the following formula may be 50 sec / 100cc or less, 40 sec / 100cc or less, 35 sec / 100cc or less, or 30 sec / 100cc or less.

[0028] △G = G1- G2

[0029] In the above formula, G1 is the Gulli permeability of a separator in which an inorganic particle layer and an adhesive layer are sequentially laminated on both sides of a porous substrate, and G2 is the Gulli permeability of the porous substrate itself. The Gulli permeability is measured according to ASTM D 726 standards using a Toyoseiki Densometer, and the unit is sec / 100cc. In addition, the above change in air permeability can also be satisfied in the case of a separator in which an inorganic particle layer and an adhesive layer are sequentially laminated on one side of the porous substrate.

[0030] The separator of the above embodiment may have excellent electrode adhesion, anti-blocking properties, and breathability, and more preferably, may have excellent electrode adhesion, anti-blocking properties, and breathability. Brief explanation of the drawing

[0031] Figure 1 is a photograph of the shape of an organic particle according to one embodiment of the present invention observed through SEM. Figure 2 illustrates the shape of an organic particle according to one embodiment of the present invention. Figure 3 is a photograph of the adhesive layer of the separator membrane of Example 1 observed through SEM. Figure 4 is a photograph of the adhesive layer of the separator membrane of Comparative Example 1 observed through SEM. Figure 5 is a photograph of the adhesive layer of the separator membrane of Comparative Example 2 observed through SEM. Figure 6 is a photograph of the adhesive layer of the separator membrane of Comparative Example 3 observed through SEM. Specific details for implementing the invention

[0032] The present disclosure is explained in more detail through the following embodiments or examples. However, the following embodiments of the present invention are merely references for explaining the present disclosure and are not limited thereto, and the present disclosure may be implemented in various forms.

[0033] Additionally, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context.

[0034] Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0035] In the present disclosure, the organic particle (100) may be a polymer particle and, as seen in FIGS. 1 and 2, may have a plurality of protrusion parts (10) and a plurality of valley parts (20) formed therein. For example, the organic particle may be an aggregate formed by the aggregation of a plurality of polymerized primary particles by surface melting, i.e., a secondary particle. The plurality of protrusion parts (10) and the plurality of valley parts (20) may be formed by the aggregation of the primary particles. The binder particle in the form of the secondary particle may refer to a particle shape having a plurality of protrusion parts corresponding to a part of the primary particles, and also having a valley or a shrinked cavity formed between the protrusion parts. For example, it refers to a shape including three or more, four or more, five or more, six or more, or eight or more convex bump parts in the form of primary particles on the surface of an organic particle, and a plurality of valley parts or depressions formed between the bump parts.

[0036] Or it may be a primary particle having a plurality of protrusions and a plurality of grooves on its surface.

[0037] The protrusions and valleys of the organic particles may be irregular in size and shape. The term "irregular" means not substantially linear, not substantially uniform, or not substantially symmetrical. The term "protrusion" refers to a part protruding from the surface of the particle and is indicated by 10 in FIGS. 1 and 2. The "valley or depression" refers to a concavity on the surface of the particle and is formed by a height difference between the plurality of protrusions formed radially from the center of the organic particles, or a concavity formed between the protrusions and is indicated by 20 in FIGS. 1 and 2.

[0038] In the present disclosure, "Dn" (where n is a real number) refers to the diameter of a particle corresponding to n% of the volume-based cumulative fraction. For example, "D50" refers to the diameter of a particle corresponding to 50% of the volume-based cumulative fraction. "D90" refers to the diameter of a particle corresponding to 90% of the volume-based cumulative fraction. "D10" refers to the diameter of a particle corresponding to 10% of the volume-based cumulative fraction. The above Dn can be derived from the particle size distribution results analyzed using a Microtrac S3500 particle size analyzer by collecting samples of the particles to be measured in accordance with ISO 13320-1 standards.

[0039] In one embodiment, the separator of the present disclosure may be a separator comprising: a porous substrate; an inorganic particle layer disposed on at least one surface of the porous substrate, wherein inorganic particles are connected to each other to form pores between the inorganic particles; and an adhesive layer disposed on the inorganic particle layer, wherein organic particles having a plurality of protrusion parts and a plurality of valley parts are connected to each other to form pores.

[0040] Below, each component of the separator is described in detail.

[0041] In one embodiment, the porous substrate may be a polyolefin-based porous substrate such as polyethylene or polypropylene, but is not particularly limited, and any porous substrate known as a porous substrate for a separator of an electrochemical device may be used. In one embodiment, the porous substrate may be manufactured as a film or a sheet, but is not particularly limited. As an example, the porous substrate may include a polyolefin such as polyethylene or polypropylene, and a multilayer film of two or more layers may be used.

[0042] In one embodiment, the thickness of the porous substrate may be, for example, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, or 6 μm or more. The upper limit is not limited, but may be, for example, 100 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, 15 μm or less, 12 μm or less, or a value between the above values, and may be 1 to 100 μm, 3 to 50 μm, 5 to 20 μm, or 5 to 15 μm for the implementation of a high-capacity battery.

[0043] In one embodiment, the inorganic particle layer may include inorganic particles and an organic binder connecting the inorganic particles to each other, and the inorganic particles may be connected and fixed by the organic binder to form pores between the inorganic particles, forming a porous inorganic particle layer. In one embodiment, the inorganic particle layer is disposed on one or both sides of a porous substrate and may be coated with an area fraction of 60% or more, 70% or more, 80% or more, or 90% or more based on the entire surface of the porous substrate, preferably 100% except for cases where there are some defects.

[0044] In one embodiment, the inorganic particle layer may be disposed on one or both sides of a porous substrate, and when the inorganic particle layer is disposed on both sides of the porous substrate, the thickness of the inorganic particle layer disposed on one side and the other side may be the same or different from each other.

[0045] In one embodiment, the thickness of the inorganic particle layer disposed on one surface of the porous substrate may be greater than 0 μm, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more, and may be 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or a value between the above values. Specifically, it may have a thickness greater than 0 μm and 5 μm, 0.1 to 5 μm, 0.2 to 3 μm, or 0.5 to 2 μm, but is not limited thereto.

[0046] In one embodiment, the inorganic particles are added to improve the heat resistance of the separator, and their types are not specifically limited. According to non-limiting examples, the inorganic particles may include one or more of metal hydroxides, metal oxides, metal nitrides, and metal carbides. Specific examples include one or more selected from the group consisting of SiO2, SiC, MgO, Y2O3, Al2O3, CeO2, CaO, ZnO, SrTiO3, ZrO2, TiO2, and AlO(OH), but are not limited thereto. To improve the stability of the battery, metal hydroxide particles such as bohemite, pseudo-bohemite, aluminum hydroxide, and magnesium hydroxide are preferred as the inorganic particles, but are not limited thereto.

[0047] In one embodiment, when boehmite is used as the inorganic particle, the specific surface area (BET) of boehmite is 10 m² 2 / g or more or 15 m 2 It may be greater than / g, but is not specifically limited to this.

[0048] In one embodiment, the D50 of the inorganic particle may be greater than 0 μm, greater than 0.05 μm, greater than 0.1 μm, less than 5 μm, less than 3 μm, less than 2 μm, less than 1 μm, less than 0.5 μm, or a value between the above values. For example, it may be greater than 0 μm and less than 5 μm, greater than 0 μm and less than 3 μm, greater than 0.05 μm and less than 2 μm, greater than 0.1 μm and less than 1 μm, or greater than 0.1 μm and less than 0.5 μm.

[0049] In one embodiment, the type of organic binder of the inorganic particle layer is not limited, provided that it is capable of connecting and fixing inorganic particles to form a porous inorganic particle layer in which the inorganic particles are connected to each other and spaces are formed between the inorganic particles. For example, the organic binder may be in a particulate form or a non-particulate form; in the case of a particulate form, it may be a particle of a shape distinct from the organic particle having a plurality of protrusion parts and a plurality of valley parts. Additionally, the organic binder may be a water-based latex.

[0050] Examples of the above organic binders include, as non-limiting examples, acrylic polymers such as polymethylmethacrylate, polybutylacrylate, and polyacrylonitrile; (3-aminopropyl)triethoxysilane, (3-aminopropyl)trimethoxysilane, (3-glycidyloxypropyl)trimethoxysilane and their oligomers or silane compounds prepared therefrom; styrene butadiene rubber; carboxylmethylcellulose (CMC); polyvinylidene fluoride (PVdF); and polyvinylpyrrolidone (PVP). It may include one or more selected from the group consisting of polyvinyl acetate (PVAc); etc., but is not limited thereto.

[0051] The content of the above organic binder may be 0.1 to 30 parts by weight, 0.2 to 10 parts by weight, or 0.2 to 5 parts by weight per 100 parts by weight of inorganic particles, but is not limited thereto.

[0052] The above-mentioned inorganic particle layer is sufficiently prepared by a conventional manufacturing method of placing an inorganic particle layer known in the art onto a porous substrate, and is not particularly limited. As a non-limiting example, a slurry of water or an organic solution containing the above-mentioned inorganic particles and an organic binder may be prepared, and then an inorganic particle layer may be formed on one or both sides of a porous substrate by applying it using one or a combination of slot die coating, roll coating, spin coating, dip coating, bar coating, die coating, slit coating, and inkjet printing.

[0053] Next, the adhesive layer of the present embodiment and the organic particles forming the adhesive layer will be described in detail.

[0054] In the present disclosure, the adhesive layer is a porous layer formed by applying a composition containing organic particles of the embodiments shown in FIGS. 1 and 2. By including the specific type of organic particles, the adhesive layer is a thin film, specifically having a thickness of 20 μm or less, yet exhibits excellent adhesion to the electrode. Furthermore, compared to the transmittance of the porous substrate itself, the increase in transmittance after the adhesive layer is formed is minimal, and no blocking occurs, thereby resolving problems that occur during battery assembly. Additionally, a separator with even better adhesion to the electrode can be provided compared to using general spherical organic particles.

[0055] The above organic particle may be a secondary particle formed by the aggregation of primary particles by the melting of the surface, or a single particle having a plurality of protrusions that are bulging out and a plurality of depressions or a plurality of valleys between the protrusions.

[0056] The above organic particles are not specifically limited, but may be "organic particles in the form of secondary particles" having a D50 particle size of, for example, 0.1 to 1.5 μm, 0.2 to 1.5 μm, or 0.3 to 1 μm. A typical form of the binder particles in the form of secondary particles may refer to a particle shape in which a plurality of polymerized primary particles melt together, for example, the surface, and aggregate, so that the surface of the aggregate protrudes due to the primary particles and valleys are formed between the primary particles, as shown in FIG. 1. As another example, it may refer to a particle in which, even without aggregation, three or more convex protrusions and a plurality of valleys or a plurality of shrinked cavity parts are formed between the protrusions in a single particle. For example, it may refer to a particle having three or more, four or more, five or more, or six or more convex protrusions on the surface of the organic particle, and a plurality of valleys or a plurality of shrinked cavity parts formed between the protrusions.

[0057] The organic particles of the present invention having the above size and shape can significantly improve adhesion to electrodes, breathability, and anti-blocking properties even when included in a relatively small amount compared to organic particles having a spherical shape as shown in FIG. 5.

[0058] In addition, the average particle size (D50) of the above organic particles is not specifically limited as long as it has the above shape, but for example, it may be 10㎛ or less, 5㎛ or less, 2㎛ or less, 1㎛ or less, 0.5㎛ or less, 0.1㎛ or more, 0.3㎛ or more, or 0.5㎛ or more, and preferably 0.1 to 10㎛, more preferably 0.1 to 1.5㎛, and very preferably 0.2 to 1.0㎛.

[0059] Within the above average particle size range, the binding effect with inorganic particles is achieved more effectively, while the adhesion to the electrode is significantly improved. In particular, when the size is 0.1 to 1.5 μm, blocking phenomena such as adhesive layers blocking each other during the transfer or stacking process, or adhesive adhering to other parts in contact with the adhesive layer causing the adhesive layer on top of the inorganic particle layer to detach, are significantly reduced, the adhesion to the electrode is dramatically increased, and thin film formation becomes possible, which is even better.

[0060] In one embodiment, the particle size distribution of the organic particles may have a D10 / D90 value of 0.3 or higher, 0.4 or higher, 0.9 or lower, 0.8 or lower, or a value between the above values. Alternatively, it may be 0.3 to 0.9, or 0.4 to 0.8. When the particle size distribution range of the organic particles is satisfied, the content of the organic particles for securing electrode adhesion can be further reduced, which is preferred as it is more advantageous for securing air permeability and anti-blocking properties, but is not necessarily limited thereto.

[0061] In one embodiment, when the ratio of the average particle size of the organic particle to the average particle size (D50) of the inorganic particle is 0.5 or more, 0.6 or more, 0.7 or more, 1.5 or less, 1.3 or less, 1.0 or less, or a value between the above values, the content of organic particles entering into the surface irregularities or pores of the inorganic particle layer can be further reduced, thereby being more preferred for ensuring air permeability and anti-blocking properties, but is not limited thereto. Preferably, the ratio of the average diameter of the organic particle to the average diameter of the inorganic particle may be 0.5 to 1.5, 0.6 to 1.3, or 0.7 to 1.0.

[0062] In one embodiment, in order to provide a separator having excellent electrode adhesion, anti-blocking properties, and breathability even at a thin thickness, the organic particles may comprise 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 99% by weight or more, or 100% based on the total weight of the adhesive layer. Since it is advantageous to achieve the purpose of the present disclosure as the amount of the organic particles in the form of secondary particles increases, there is no particular limit on the upper limit of the content.

[0063] According to one embodiment, the separator membrane can have excellent physical properties such as electrode adhesion, breathability, and anti-blocking properties, which are relatively superior compared to a polymer identical to the organic particles but with a shape that is spherical or circular without grooves as shown in FIG. 5, because the organic particles constituting the adhesive layer formed on top of the inorganic particle layer have a specific shape defined above as shown in FIG. 1. Therefore, the composition of the organic particles of the present invention is not particularly limited, and any composition of organic particles conventionally used in the relevant technical field to improve electrode adhesion can be applied.

[0064] As a non-limiting example, the above organic particles may be manufactured from cross-linked or non-cross-linked particulate acrylic or fluorine polymers, or may have a core-shell structure. The above core-shell particulate acrylic polymer may be, for example, polymerized by including an acrylic monomer and, if necessary, other comonomers and a crosslinking agent on the surface of a rubber or crosslinking particle of the core, but is not particularly limited.

[0065] The organic particles of the specific form according to the above embodiment are preferred because, due to their structural characteristics, they can significantly improve electrode adhesion even in small amounts, and if they have a high glass transition temperature, they can further improve anti-blocking properties. In this case, the glass transition temperature (Tg) of the organic particles may be 50°C or higher, 60°C or higher, 90°C or lower, 80°C or lower, 70°C or lower, or a value between the above values, and may be, for example, 50 to 90°C, 55 to 75°C, or 60 to 70°C, but is not limited thereto.

[0066] In one embodiment, the adhesive layer may optionally include other components, such as lubricants and surfactants, in addition to the organic particles, which are known in the art to be added to the electrode adhesive organic layer of a separator, but are not particularly limited.

[0067] In one embodiment, the adhesive layer is a porous particle layer in which the organic particles are connected and fixed to each other, and may have an area fraction of 60% or more, 70% or more, 80% or more, or 100% based on the entire surface of the inorganic particle layer, and may be 100% laminated except for defects that occur specifically. In one embodiment, after forming a porous inorganic particle layer on a porous substrate, a porous adhesive layer of the shape and size above may be laminated on the porous inorganic particle layer to further improve the air permeability and ion conductivity of the separation membrane, but is not particularly limited.

[0068] In one embodiment, the thickness of the adhesive layer may be greater than 0 μm, greater than 0.1 μm, greater than 0.2 μm, greater than 0.3 μm, less than 2 μm, less than 1.5 μm, less than 1 μm, less than 0.9 μm, less than 0.7 μm, or a value between the above values, and the thickness of the adhesive layer may be greater than 0 μm and less than 2 μm, or 0.1 to 1 μm for the implementation of a high-capacity battery.

[0069] In one embodiment, the total thickness of the separator, in which an inorganic particle layer and an adhesive layer are respectively disposed on one or both sides of a porous substrate, may be 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 30 μm or more, 50 μm or less, 30 μm or less, 20 μm or less, 15 μm or less, or a value between the above values. The total thickness of the separator may be 5 to 50 μm, 5 to 25 μm for the implementation of a high-capacity battery, or 7 to 20 μm, but is not particularly limited.

[0070] In one embodiment, the content of organic particles in the adhesive layer is 0.2 g / m² 2 Above, 0.5g / m² 2 Above, 1g / m² 2 Above, 2.0g / m² 2 Below, 1g / m² 2 Below, 0.5g / m² 2 The value may be less than or between the above figures, preferably 0.2 to 1.0 g / m² 2 It could be.

[0071] The method for manufacturing the above-mentioned specific type of organic particle is not particularly limited, but in one embodiment, a polymerization solution of primary particles is prepared by polymerizing various radical polymerizable monomers such as acrylic or fluorine-based monomers by emulsion polymerization or suspension polymerization, and the solution is spray-dried for several seconds at a high temperature of 200°C to 300°C and classified by size to produce an aggregate in the form of a secondary particle, or protrusions and valleys can be formed by removing non-reactive monomers from the polymer particles by vacuum distillation after suspension polymerization, but is not limited thereto.

[0072] The adhesive layer may be placed on an inorganic particle layer using any method known in the art and is not particularly limited by such means. As a non-limiting example, water may be added to the organic particles and stirred to prepare a slurry for the adhesive layer, and then the prepared slurry may be applied to the inorganic particle layer by one or a combination of slot die coating, roll coating, spin coating, dip coating, bar coating, die coating, slit coating, and inkjet printing, and dried to place the adhesive layer on the inorganic particle layer.

[0073] In one embodiment, the separator may be laminated on a carbon sheet with a thickness of 200 μm so that the adhesive layer of the separator faces it, then bonded by pressing with a heat press at 80° and 20 MPa for 30 seconds, and then peeled 180° using a UTM machine according to ASTM D 903 and the electrode adhesion strength measured may be 1.5 gf / 15mm or more, 2.0 gf / 15mm or more, 2.5 gf / 15mm or more, or 3 gf / 15mm or more. Alternatively, it may be 1.5 gf / 15mm to 4.0 gf / 15mm, or 2.0 to 4.0 gf / 15mm.

[0074] According to the above embodiment, organic particles having the above shape and simultaneously having a high glass transition temperature are preferred because they can ensure sufficient electrode adhesion and improve anti-blocking properties even when applied to an inorganic particle layer by using a small amount for thin coating or by distributing well even when the coating area is insufficient.

[0075] For example, when two separation membranes, each having a porous substrate, an inorganic particle layer, and an adhesive layer sequentially laminated, are arranged so that the adhesive layers face each other, and then compressed at a temperature of 60°C and a pressure of 7.5 MPa for 1 hour, and then separated, if the adhesive layer is partially or completely peeled off and blocking between the membrane surfaces is checked using SEM, excellent anti-blocking properties can be secured in which no blocking is detected.

[0076] In one embodiment, the separator may have a change in air permeability (△G) expressed by the following formula of 50 sec / 100cc or less, 45 sec / 100cc or less, 40 sec / 100cc or less, or 35 sec / 100cc or less.

[0077] △G = G1- G2

[0078] In the above formula, G1 is the Gulli permeability of a separator in which an inorganic particle layer and an adhesive layer are sequentially laminated on both sides of a porous substrate, and G2 is the Gulli permeability of the porous substrate itself. The Gulli permeability is measured according to ASTM D 726 standards using a Toyoseiki Densometer, and the unit is sec / 100cc.

[0079] According to one embodiment, the separator may have excellent electrode adhesion, anti-blocking properties, and breathability, and more preferably, may have excellent electrode adhesion, anti-blocking properties, and breathability.

[0080] Another embodiment provides an electrochemical device comprising the above-described separator. The electrochemical device may be an energy storage device and is not particularly limited, but a non-limiting example may be a lithium secondary battery. Since the lithium secondary battery is publicly known and its configuration is also known, it is not described in detail in this disclosure.

[0081] A lithium secondary battery according to one embodiment may include the aforementioned separator between a positive electrode and a negative electrode. In this case, the positive electrode and the negative electrode may be any of the types typically used in lithium secondary batteries without limitation.

[0082] The present disclosure is explained in more detail below based on examples and comparative examples. However, the following examples and comparative examples are merely illustrative of the present disclosure and are not intended to limit the present disclosure.

[0083] The following is the method for measuring the physical properties of the membrane.

[0084] 1. Electrode adhesion

[0085] The adhesive layer of the separator is laminated onto a 200㎛ thick carbon sheet (TOYO Tanso Korea, PF-20HP) so that they face each other, and then bonded by pressing with a heat press at 80℃ and 20MPa for 30 seconds. Afterward, the electrode adhesion strength is measured by peeling at 180° using an INSTRON UTM machine according to ASTM D 903. If the adhesion strength of the separator's adhesive layer is too low to even peel using the UTM machine, it is evaluated as 'unmeasurable'.

[0086] 2. Change in air permeability

[0087] The change in air permeability △G is calculated as follows.

[0088] △G = G1- G2

[0089] In the above formula, G1 is the Gulli permeability of a separator in which an inorganic particle layer and an adhesive layer are sequentially laminated on both sides of a porous substrate, and G2 is the Gulli permeability of the porous substrate itself. Gulli permeability is measured according to ASTM D 726 standards using a Toyoseiki Densometer, and the time taken for 100 cc of air to pass through an area of ​​1 square inch of the separator is recorded in seconds. The unit is sec / 100cc.

[0090] 3. Anti-blocking properties

[0091] Two separator membranes, each having a porous substrate, an inorganic particle layer, and an adhesive layer laminated thereon, were placed so that the adhesive layers faced each other, and then compressed at a temperature of 60°C and a pressure of 7.5 MPa for 1 hour. Next, when peeled at 180° according to ASTM D903, it was evaluated whether the adhesive layers adhered to each other and delaminated partially or completely. If even partial delamination occurred, it was considered that blocking had occurred; if the adhesive layers separated intact without delamination, it was considered that no blocking had occurred. The occurrence of blocking is confirmed via SEM. If blocking is confirmed via SEM, it is evaluated as 'NG', and if blocking is not confirmed, it is evaluated as 'OK'.

[0092] 4. Method for measuring average particle size

[0093] According to ISO 13320-1 standards, the average particle size (D50), D10, and D90 were measured using the Microtrac S3500 particle size analyzer.

[0095] [Example 1]

[0096] 1) Preparation of slurry for adhesive layer

[0097] An acrylic latex (an acrylic latex polymerized from methyl methacrylate and butyl methacrylate) having an average particle size (D50) of 550 nm and a glass transition temperature (Tg) of 65°C, formed from organic particles of the form shown in Fig. 1, was added to water to a solid content of 5% by weight and stirred to prepare a uniformly mixed adhesive layer slurry. At this time, the D10 / D90 of the organic particles was 0.57.

[0098] 2) Preparation of slurry for inorganic particle layer

[0099] A slurry containing 40% by weight of inorganic particles was prepared by mixing 3 parts by weight of a water-soluble acrylic binder (Ashland, PVP K120) and water with 100 parts by weight of boehmite particles (Nabaltec, Apyral AOH60) having a D50 of 600 nm as inorganic particles.

[0100] 3) Separator manufacturing

[0101] An inorganic particle layer was formed by applying the slurry for the inorganic particle layer to both sides of a polyolefin-based porous substrate (SK Innovation, ENPASS) having a Gulli permeability of 125 sec / 100cc and a thickness of 8.5 μm using two slot coating dies and drying sufficiently at 40°C. Subsequently, an adhesive layer was formed by applying the slurry for the adhesive layer to the upper surface of the inorganic particle layer and drying sufficiently at 40°C. The thickness of the inorganic particle layer of the separator was 1.5 μm, the thickness of the adhesive layer was 0.5 μm, and the total thickness of the separator was 12.5 μm. The content of organic particles in the coated adhesive layer was 0.4 g / m². 2 Figure 3 includes a photograph of the surface of the adhesive layer, and its physical properties are listed in Table 1.

[0103] [Example 2]

[0104] A separator was prepared in the same manner as in Example 1, except that the D50 was 400 nm when preparing the slurry for the adhesive layer. The results are listed in Table 1.

[0106] [Example 3]

[0107] A separation membrane was prepared under the same conditions as in Example 1, except that an acrylic latex with a D50 of 1.8 μm and a glass transition temperature (Tg) of 65°C was coated in the amounts listed in Table 1 as the composition of the organic particles of Example 1. The results are listed in Table 1.

[0109] [Example 4]

[0110] A separator was prepared under the same conditions as in Example 1, except that when preparing the slurry for the adhesive layer, an acrylic latex with a D50 of 1.0 μm and a glass transition temperature (Tg) of 62°C, having the same composition as the organic particles in Example 1, was coated in the amount listed in Table 1. The results are recorded in Table 1.

[0112] [Comparative Example 1]

[0113] The procedure was carried out in the same manner, except that the acrylic latex of Example 1 was dissolved in an organic solution and applied to an inorganic particle layer. The results are shown in Figure 4 and Table 1.

[0115] [Comparative Example 2]

[0116] A separation membrane was prepared under the same conditions as in Example 1, except that acrylic latex, prepared by suspension polymerization using the same monomer as in Example 1 as perfectly spherical organic particles as in Example 1, was coated in the amount listed in Table 1 with the spherical D50 of Fig. 5, which has a glass transition temperature (Tg) of 65°C, instead of the organic particles of Example 1. The results are shown in Fig. 5 and Table 1.

[0118] [Comparative Example 3]

[0119] A separation membrane was prepared under the same conditions as in Example 1, except that instead of the organic particles of Example 1, acrylic latex with a D50 of 200 nm and a glass transition temperature (Tg) of 65°C was coated as perfectly spherical organic particles in the amount listed in Table 1. The results are shown in Figure 6 and Table 1.

[0121] The results of the physical property evaluation of the separation membranes prepared in the above examples and comparative examples of the present invention are summarized in Table 1 below.

[0123] organic particles Average diameter of organic particles / Average diameter of inorganic particles Electrode adhesion (gf / 15mm) Change in air permeability △G (sec / 100cc) Anti-blocking properties (OK / NG) D50(nm) Tg(℃) Content (g / m²) 2 ) Example 1 550 65 0.4 0.92 2.7 27 OK Example 2 400 65 0.8 0.67 2.5 33 OK Example 3 1800 65 0.2 3.0 2.5 19 NG Example 4 1000 62 0.3 1.67 2.8 22 OK Comparative Example 1 550 65 0.4 - Unmeasurable 86 OK Comparative Example 2 540 65 0.4 0.9 Unmeasurable 27 OK Comparative Example 3 200 65 0.8 0.33 Unmeasurable 38 OK

[0124] Referring to the results and drawings in Table 1 above, as shown in Fig. 3, the adhesive layer is formed with organic particles having a secondary particle shape including convex protrusions on the surface and valley parts interposed between the protrusions, and in the case of Examples 1 and 2, where the ratio of the average particle size of organic particles to inorganic particles is between 0.5 and 1.5 and the average particle size of the organic particles is 1.5 μm or less, it was confirmed that the adhesive layer containing the best electrode adhesion and anti-blocking properties was well formed on the inorganic particle layer.

[0125] In addition, in the case of Example 4, where the average size of the organic particles is 1 μm and the ratio of organic particles to inorganic particles is 1.67, it can be seen that it has significantly superior electrode adhesion and anti-blocking characteristics compared to the comparative examples, although it is inferior to Examples 1 and 2. In the case of Example 3, where the average size is 1.8 μm and the ratio of organic particles to inorganic particles is 3, it can be seen that it exhibits superior adhesion compared to the comparative examples, although it is inferior in anti-blocking properties compared to Examples 1, 2, and 4.

[0126] On the other hand, Comparative Example 1 used a soluble acrylic polymer, and as shown in Fig. 4, the surface pores were blocked, resulting in poor air permeability and very low electrode adhesion. In addition, Comparative Examples 2 and 3, which had spherical adhesive layers, had spherical adhesive layers as shown in Figs. 5 and 6, and in this case, the electrode adhesion was poor and the anti-blocking properties were very poor.

[0127] As described above, the present disclosure has been explained by specific details and limited embodiments, but this is provided only to aid in a more comprehensive understanding of the present disclosure. The present disclosure is not limited to the above embodiments, and various modifications and variations are possible from this description by those skilled in the art to which the present disclosure pertains.

[0128] Accordingly, the present disclosure is not limited to the embodiments described above, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to be within the scope of the present disclosure. Explanation of the symbols

[0129] 100: Organic particles 10: Protrusion 20: Golbu

Claims

Claim 1 A separator comprising: a porous substrate; an inorganic particle layer disposed on at least one surface of the porous substrate, wherein inorganic particles are connected to each other to form pores between the inorganic particles; and an adhesive layer disposed on the inorganic particle layer, wherein organic particles having a plurality of protrusion parts and a plurality of valley parts are connected to each other to form pores; wherein the organic particles are cross-linked or non-cross-linked acrylic organic particles, and the organic particles are secondary particles formed by primary particles aggregating together by surface melting to form a plurality of protrusion parts and a plurality of valley parts, or primary particles having a plurality of protrusion parts and a plurality of valley parts on their surface. Claim 2 A separation membrane according to claim 1, wherein the ratio of the average particle size (D50) of the organic particles to the average particle size (D50) of the inorganic particles is 0.5 to 1.

5. Claim 3 A separation membrane according to claim 1, wherein the D50 of the organic particles is 0.1 to 1.5 μm. Claim 4 A separation membrane according to claim 1, wherein the particle size distribution D10 / D90 of the organic particles is 0.3 to 0.

9. Claim 5 A separation membrane according to claim 1, wherein the glass transition temperature (Tg) of the organic particles is 50 to 90°C. Claim 6 A separator according to claim 1, wherein the thickness of the adhesive layer is greater than 0㎛ and less than or equal to 2㎛. Claim 7 delete Claim 8 A separation membrane according to claim 1, wherein the adhesive layer comprises 70% by weight or more of the organic particles based on the total weight of the adhesive layer. Claim 9 In claim 1, the adhesive layer contains 0.2 to 2.0 g / m² of the organic particles 2 A separator containing Claim 10 The separator according to claim 1, wherein the separator is laminated so that the adhesive layer of the separator faces a carbon sheet (TOYO Tanso Korea, PF-20HP) with a thickness of 200 μm, then bonded by pressing with a heat press at 80° and 20 MPa for 30 seconds, and then the electrode adhesion strength measured by peeling at 180° using an INSTRON UTM machine according to ASTM D 903 is 1.5 gf / 15mm to 4.0 gf / 15mm. Claim 11 In claim 10, the above-mentioned membrane is a membrane in which the change in air permeability ΔG measured by the following formula is 50 sec / 100cc or less. ΔG = G1 - G2. In the above formula, G1 is the Gulli permeability of a membrane in which an inorganic particle layer and an adhesive layer are sequentially laminated on both sides of a porous substrate, and G2 is the Gulli permeability of the porous substrate itself. The Gulli permeability is measured according to ASTM D 726 standards using a Toyoseiki Densometer, and the unit is sec / 100cc. Claim 12 In claim 11, the separator is a separator in which, when two separators are arranged so that the adhesive layers face each other, then compressed at a temperature of 60°C and a pressure of 7.5 MPa for 1 hour, and then peeled at 180° according to ASTM D903, the adhesive layers do not adhere to each other and the phenomenon of partial or complete peeling does not occur, and the adhesive layers remain separated without blocking. Claim 13 An electrochemical device comprising a separator according to any one of claims 1 to 6 and 8 to 12.

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