Separator for electrochemical device and method for manufacturing same

Abstract

A separator according to the present invention not only has excellent adhesion to an electrode, but also can ensure sufficient porosity, and thus has excellent resistance and ion conductivity characteristics. In addition, the lamination process time can be reduced during the manufacture of electrode assemblies, and thus high process efficiency can be achieved in manufacturing batteries.

Description

Separator for electrochemical devices and method for manufacturing the same

[0001] This application claims priority to Korean Patent Application No. 10-2023-0194080, filed December 28, 2023. The present invention relates to a separator for electrochemical devices such as lithium-ion secondary batteries.

[0002]

[0003] Non-aqueous secondary batteries, such as lithium-ion secondary batteries, are widely used as power sources for portable electronic devices such as laptops, mobile phones, digital cameras, and camcorders. Furthermore, due to their high energy density, these batteries are also being considered for use in automobiles.

[0004] Lithium secondary batteries currently in production use porous polymer substrates, such as polyolefin polymer resins, as separator substrates to prevent short circuits between the positive and negative electrodes. However, these polymer substrates have low heat resistance due to shrinkage or melting at high temperatures. Therefore, when the battery is exposed to internal or external stimuli, the separator shrinks or melts, increasing the likelihood of the positive and negative electrodes contacting each other and causing a short circuit. This can lead to a rapid release of electrical energy, potentially leading to battery explosion or fire.

[0005] Accordingly, in order to solve the above problems, a method of improving heat resistance by forming a porous filler layer in which inorganic particles and binder resin are mixed on at least one side of a polymer substrate is widely used. However, the heat-resistant layer must have sufficient porosity in terms of securing an ion transport path and electrolyte impregnation. The pores of the heat-resistant layer originate from the interstitial volume between the inorganic particles. However, if the content of the binder resin is high, the interstitial volume is blocked by the binder resin, making it difficult to secure sufficient porosity. On the other hand, if the content of the binder resin is insufficient, the electrode and the separator may not be closely adhered, and thus the electrode and the separator may become separated during the battery manufacturing process or battery operation.

[0006] Meanwhile, electrode assemblies are typically manufactured using a roll-to-roll continuous process, followed by a lamination process that pressurizes (and, if necessary, applies hot presses) the laminated electrodes and separator. To ensure the desired level of electrode-separator bonding, sufficient lamination time must be secured, but this can lead to reduced productivity, including reduced production speeds.

[0007] Accordingly, continuous research and development is required to secure sufficient porosity and adhesive strength (between electrodes and separators) and process efficiency in separators for electrochemical devices.

[0008]

[0009] The present invention aims to provide a separator that can ensure high adhesion to electrodes and improve battery production efficiency. Furthermore, the present invention aims to provide an electrochemical device comprising the separator. It will be readily apparent that other objectives and advantages of the present invention can be achieved by the means or methods described in the claims, and combinations thereof.

[0010]

[0011] The first aspect of the present invention relates to a separator for an electrochemical device, wherein the separator comprises a porous polymer substrate and an inorganic coating layer covering one surface or both surfaces of the porous polymer substrate.

[0012] The above-mentioned inorganic coating layer comprises a plurality of adhesive polymer columns of a predetermined volume, wherein the polymer columns are made of a polymer material and do not have pores,

[0013] At least a portion of the polymer column is exposed to the surface of the inorganic coating layer and another portion is in contact with the surface of the porous substrate,

[0014] At least one polymer column is spaced apart from the other polymer columns by a predetermined distance,

[0015] The space between the above polymer columns is filled with inorganic particles,

[0016] The above polymer column has a storage modulus (G') at room temperature of 100 Pa or more and 3,500 Pa or less, and a solubility in THF of 15% to 70%, and the solubility is according to the following [Formula 1].

[0017] [Formula 1]

[0018] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0019]

[0020] In the above-described aspect of the present invention, the separation membrane may have a first compression ratio of 20% to 25% by first compression under pressurized conditions of 2.0 MPa to 4.0 MPa and 55°C to 65°C.

[0021] The above first compression ratio is a value calculated by [Formula 2] below and refers to the compression ratio (dry compression ratio) before the separator comes into contact with the electrolyte.

[0022] Height of the inorganic coating layer after compression under the above conditions (T c ) is 1.1xT i < Tc < 1.5 x T i And, the protrusion height of the polymer column after compression can be 1㎛ or more.

[0023]

[0024] [Formula 2]

[0025] First compression ratio (%) = {(Initial thickness before first compression - Thickness after first compression) / (Thickness before first compression)} x 100.

[0026] In any one of the aforementioned aspects of the present invention, the separator may have a second compression ratio of 30% or more by a second compression under a pressurized condition of 0.5 MPa to 1.5 MPa and 35°C to 85°C, and the second compression ratio is calculated by the following [Formula 3], and the second compression ratio is a compression ratio (wet compression ratio) in a state where the separator is immersed in an electrolyte for 5 minutes or more after the first compression and the electrolyte on the surface is removed and the separator is pressurized under the above conditions.

[0027] The thickness (Tc) of the inorganic coating layer after the second compression is 1.0 x T i < T c ≤ 1.1 x T i and,

[0028] The protrusion thickness of the polymer column after the second compression may be 1 μm or less.

[0029]

[0030] [Formula 3]

[0031] Second compression ratio (%) = {(Initial thickness before second compression - Thickness after second compression) / (Thickness before second compression)} x 100.

[0032]

[0033] The present invention relates to any one of the aforementioned aspects, wherein D of the polymer column 50 D of silver inorganic particles 50 It can be more than twice as large.

[0034] In any one of the aforementioned aspects of the present invention, the inorganic coating layer may contain 10 to 50 volume% of the polymer column based on 100 volume% of the inorganic particles.

[0035] The present invention has a thickness (T) of the inorganic particle portion in any one of the aforementioned aspects. i ) is a polymer column D 50 It may be less than 85% of the total.

[0036] The present invention relates to any one of the aforementioned aspects, wherein D of the polymer column 10 Silver D 50 More than 30% of D90 is D 50 It is less than 200% of .

[0037] In any one of the aforementioned aspects of the present invention, the area occupied by the polymer column relative to 100% of the surface area of ​​the inorganic coating layer based on the top view of the separation membrane may be 10% to 50%.

[0038] In any one of the aforementioned aspects of the present invention, at least one polymer column included in the inorganic coating layer may have an area (a) of a cross-section of the polymer column confirmed in the lower 5% from the lowest portion of the inorganic coating layer toward the surface, and an area (b) of a cross-section of the column confirmed in the upper 5% from the top portion toward the bottom, wherein the area (a) is greater than the area (a).

[0039] In any one of the aforementioned aspects of the present invention, at least one polymer column included in the inorganic coating layer has a diameter (a) of a lower portion of the polymer column that is shorter than a diameter (b) of an upper portion of the column in a cross-section of the polymer column confirmed in a vertical cross-section of the inorganic coating layer, and the ratio of the diameter (b) to the diameter (a) may be 2 to 20.

[0040] In any one of the aforementioned aspects of the present invention, the inorganic coating layer may have a pore structure due to interstitial volume between inorganic particles.

[0041] The present invention relates to an electrochemical device comprising a separator for an electrochemical device according to any one of the aforementioned aspects.

[0042] The present invention relates to a method for manufacturing a separator for an electrochemical device according to any one of the aforementioned aspects, the method comprising the steps of: preparing a laminate comprising at least one anode, at least one separator, and at least one cathode, wherein the separator is interposed between the anode and the cathode and is laminated at least once;

[0043] A step of manufacturing a first electrode assembly by pressing the laminate at a strength of 3.0 MPa to 4.0 MPa under temperature conditions of 55°C to 65°C;

[0044] A step of impregnating the first electrode assembly with an electrolyte; and

[0045] A step of applying a pressure of 0.5 MPa to 1.5 MPa to the above-mentioned impregnated first electrode assembly is included.

[0046] The present invention relates to a manufacturing method according to any one of the aforementioned aspects, wherein pressure is applied to the impregnated first electrode assembly to bring the separator and the anode and / or the separator and the cathode into close contact, and the pressure application can be performed at a temperature of 35°C to 45°C.

[0047] The present invention relates to a manufacturing method according to any one of the aforementioned aspects, wherein the step of impregnating the first electrode assembly with an electrolyte comprises housing the first electrode assembly in a battery case, and an aging step may be further performed before applying pressure after the impregnation.

[0048] In the present invention, each of the above embodiments may be implemented independently. Alternatively, two or more of the above embodiments may be implemented in combination.

[0049]

[0050] The separator according to the present invention not only exhibits excellent adhesion to electrodes but also secures sufficient porosity, resulting in superior resistance and ionic conductivity characteristics. Furthermore, it can shorten the lamination process time during electrode assembly manufacturing, thereby achieving high process efficiency in battery manufacturing.

[0051]

[0052] The drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further enhance the understanding of the technical spirit of the present invention. Therefore, the present invention is not limited to the matters described in these drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation.

[0053] Figure 1 is a schematic diagram showing one embodiment of the separation membrane of the present invention.

[0054] Figure 2 shows an SEM image of the surface of the inorganic coating layer of the separator manufactured in Example 1.

[0055] Figure 3 shows an SEM image of the surface of the inorganic coating layer of the separator manufactured in Example 1 after the first compression.

[0056] Figure 4 shows an SEM image of the surface of the inorganic coating layer of the separator manufactured in Comparative Example 2.

[0057] Figure 5 shows an SEM image of the surface of the inorganic coating layer of the separator manufactured in Comparative Example 2 after the first compression.

[0058]

[0059] Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings. Rather, they should be interpreted with meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to best explain his or her invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0060] Throughout this specification, when it is said that a part "includes" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0061] In addition, the terms "about", "substantially", etc. used throughout this specification are used in the sense of numerical values ​​or near numerical values ​​when manufacturing and material tolerances inherent to the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0062] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0063] Entry D in the original specification 50 D means the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. That is, D 50 refers to the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. In addition, D 10 D means the particle size at the 10% point of the cumulative distribution of particle numbers according to particle size.90 It means the particle size at the 90% point of the cumulative distribution of the number of particles according to the particle size. The particle size can be measured using the laser diffraction method. Specifically, after the powder to be measured is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) and the particle size distribution is calculated by measuring the difference in the diffraction pattern according to the particle size when the particles pass through the laser beam. By calculating the particle diameters at the points where the particle number is 10%, 50% and 90% of the cumulative distribution of the number of particles according to the particle size in the measuring device, respectively, D 10, D 50 and D 90 can be measured.

[0064] Certain terminology used in the following detailed description of the invention is for convenience only and is not limiting. The words "left," "right," "upper," and "lower" may indicate directions in the drawings to which reference is made and should not be limiting. The words "inwardly" and "outwardly" indicate directions toward or away from the geometric center of the designated device, system, and its components, respectively. The words "front," "rear," "upper," and "lower," and related words and phrases indicate positions and orientations in the drawings to which reference is made and should not be limiting. These terms include the words listed above, their derivatives, and words of similar import.

[0065] In the present invention, the glass transition temperature (Tg) can be measured through a DSC curve derived from a temperature increase analysis at 10°C / min using a differential scanning calorimeter (DSC).

[0066] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same. In the present invention, the electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept that includes a primary battery and a secondary battery. The secondary battery is a concept that encompasses lithium-ion batteries, nickel-cadmium batteries, nickel-hydrogen batteries, etc., and is capable of charging and discharging.

[0067]

[0068] membrane

[0069] In one embodiment of the present invention, the separator includes a porous substrate (10) and an inorganic coating layer (20) formed on at least one side or both sides of the porous substrate. Fig. 1 is a schematic diagram illustrating a cross-section of the separator of the present invention, in which inorganic particles (200) and polymer columns (100) are arranged. In particular, the diagram illustrates an aspect before compression (pressurization) during the manufacturing process of the separator, in which the polymer columns protrude beyond the inorganic particle filling portion. The compression may mean that an external force is artificially applied during the battery assembly process.

[0070]

[0071] The separator may have a total thickness of 5.0 μm to 30 μm and may be appropriately adjusted within the above range. For example, it may be 25.0 μm or less, 20.0 μm or less, 15.0 μm or less, 12.0 μm or less, or 10.0 μm or less. In one embodiment of the present invention, the separator may be introduced during the manufacture of an electrode assembly and, after being flattened by performing a pressurizing process such as lamination, may have a thickness of 15.0 μm or less, 14.0 μm or less, 13.0 μm or less, 12.0 μm or less, 11.0 μm or less, or 10.0 μm or less. In addition, the separator may have a porosity of about 25 vol% to 80 vol%. The porosity may be appropriately adjusted within the above-mentioned range. For example, the porosity may be 30 vol% or more, or 35 vol% or more, or 40 vol% or more, or 50 vol% or more, or 55 vol% or more. Alternatively, the porosity may be 70 vol% or less, or 65 vol% or less, or 60 vol% or less, or 55 vol% or less. Meanwhile, the separation membrane may exhibit a permeability in a range of about 50 sec / 100 cc or more and about 250 sec / 100 cc or less. The permeability may be appropriately controlled within the above-mentioned range. For example, the permeability may be 60 sec / 100 cc or more, or 70 sec / 100 cc or more, or 100 sec / 100 cc or more, or 120 sec / 100 cc or more, or 150 sec / 100 cc or more. Alternatively, the porosity may be 220 sec / 100cc or less, or 200 sec / 100cc or less, or 180 sec / 100cc or less.

[0072] In one embodiment of the present invention, the thickness of the separator can be determined by cutting a cross-section of a separator sample, observing it through an SEM, and then taking the thickness of the thickest point as the thickness of the separator. Alternatively, the thicknesses of two or more arbitrary points can be measured and the average value thereof can be taken as the thickness of the separator. If the thicknesses of four or more points are measured, the lowest and / or highest values ​​can be excluded and the average value of the remaining values ​​can be taken.

[0073]

[0074] In one embodiment of the present invention, the porosity can be calculated by calculating the true density of the measurement object from the density (apparent density) of the measurement object such as a membrane, the composition ratio of materials included in the measurement object, and the density of each component, and calculating the porosity from the difference between the apparent density and the true density (net density). For example, the porosity can be calculated by [Formula 4] below.

[0075]

[0076] [Formula 4]

[0077] Porosity (vol%) = {1-(apparent density / true density)} × 100

[0078]

[0079] Meanwhile, the apparent density in the above formula can be calculated from [Formula 5] below.

[0080]

[0081] [Formula 5]

[0082] Apparent density (g / cm) 3 ) = {Weight of the measurement object [g] / (Thickness of the measurement object [cm] × Area of ​​the measurement object [cm 2 ])}

[0083]

[0084] Alternatively, the porosity or pore size can be measured using an adsorbent gas such as nitrogen using BELSORP (BET equipment) from BEL JAPAN, or by a method such as mercury intrusion porosimetry or capillary flow porosimetry.

[0085] The term 'permeability' used in this specification means the time it takes for 100 cc of air to permeate a permeability measurement target such as a membrane or porous substrate, and the unit thereof can be second / 100 cc, can be used interchangeably with permeability, and is typically expressed as a Gurely value, etc. In a specific embodiment of the present invention, the permeability can be measured in accordance with JIS P8117. In addition, the air permeability P1 measured in an object having a thickness T1 can be converted into the permeability P2 when the thickness of the object is 20 µm by the formula: P2 = (P1 × 20) / T1.

[0086]

[0087] porous substrate

[0088] The above porous substrate refers to a substrate having multiple pores formed therein as an ion-conducting barrier that allows ions to pass through while blocking electrical contact between the cathode and anode. The pores are structured to be interconnected, allowing gas or liquid to pass from one side of the substrate to the other.

[0089] The material constituting the porous substrate can be any organic or inorganic material with electrical insulation properties. In particular, from the perspective of imparting a shutdown function to the substrate, it is preferable to use a thermoplastic resin as the constituent material of the substrate. Here, the shutdown function refers to a function in which, when the battery temperature rises, the thermoplastic resin melts and closes the pores of the porous substrate, thereby blocking the movement of ions and preventing thermal runaway of the battery. Suitable thermoplastic resins include those with a melting point below 200°C, and polyolefin is particularly preferred.

[0090] In addition, at least one of polymer resins such as polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalene may be further included. The porous substrate may be, but is not particularly limited to, a non-woven fabric, a porous polymer film, or a laminate of two or more thereof.

[0091]

[0092] Specifically, the porous polymer substrate is one of the following a) to e).

[0093]

[0094] a) A porous film formed by melting / extruding a polymer resin,

[0095] b) A multilayer film in which two or more layers of the porous film of a) above are laminated,

[0096] c) A nonwoven web manufactured by accumulating filaments obtained by melting / spinning a polymer resin.

[0097] d) A multilayer film in which two or more layers of the nonwoven web of the above b) are laminated,

[0098] e) A porous composite membrane having a multilayer structure comprising two or more of the above a) to d).

[0099]

[0100] In the present invention, the porous substrate may have a thickness ranging from 3 μm to 12 μm or from 5 μm to 12 μm. If the thickness falls short of the above values, the conductive barrier function is insufficient, whereas if the thickness exceeds the above range (i.e., is too thick), the resistance of the separator may excessively increase.

[0101] In one embodiment of the present invention, the weight average molecular weight of the polyolefin may be from 100,000 to 5,000,000. For example, the molecular weight (Mw) may be 200,000 or more, or 500,000 or more, or 700,000 or more, or 1,000,000 or more. Alternatively, the molecular weight may be 4,000,000 or less, or 3,000,000 or less, or 2,500,000 or less, or 2,000,000 or less, or 1,500,000 or less. The unit of the molecular weight (Mw) may be g / mol. If the weight average molecular weight is less than 100,000, it may be difficult to secure sufficient mechanical properties. In addition, if it exceeds 5,000,000, the shutdown characteristics may deteriorate or molding may become difficult. In addition, the puncture strength of the porous substrate may be 300 gf or more from the viewpoint of improving the manufacturing yield. The puncture strength of a porous substrate refers to the maximum puncture load (gf) measured by performing a puncture test using a Kato tech KES-G5 handy compression tester under conditions of a needle tip curvature radius of 0.5 mm and a puncture speed of 2 mm / sec.

[0102] In a specific embodiment of the present invention, the porous polymer substrate may be any planar porous polymer substrate used in an electrochemical device, and for example, an insulating thin film having high ion permeability and mechanical strength, a pore diameter of generally 10 nm to 200 nm, and a thickness of generally 2 μm to 12 μm may be used. Meanwhile, the porous substrate may have a porosity of 20 vol% to 60 vol% or 30 vol% to 60 vol%, and a pore size of 10 nm to 200 nm, but is not particularly limited thereto.

[0103]

[0104] Inorganic coating layer

[0105] In the present invention, the separation membrane includes an inorganic coating layer formed on one surface of the porous substrate. The inorganic coating layer includes a plurality of polymer columns and a plurality of inorganic particles.

[0106] In a specific embodiment of the present invention, the inorganic particles in the inorganic coating layer may be included in a range of about 50 wt% to 95 wt%, or about 70 wt% to 90 wt%, relative to 100 wt% of the inorganic coating layer. In addition, the polymer column may be included in a range of 10 wt% to 40 wt%, or preferably 20 wt% to 35 wt%, relative to 100 wt% of the inorganic particles.

[0107] If the content of the polymer column in the inorganic coating layer is low, it is difficult to secure the desired level of adhesive strength. However, if the content exceeds the above range and is too large, the Gurley value and / or porosity of the separation membrane may decrease, which is not desirable.

[0108] Meanwhile, the total area of ​​the polymer columns in the planar image of the inorganic coating layer may be 10% to 80%, preferably 10% to 50%, of the total area of ​​the inorganic coating layer. The total area of ​​the polymer columns may be before compression, after compression, or both before and after compression.

[0109] In the above-described inorganic coating layer, the polymer columns may be clustered in groups of two or more polymer columns, or the individual polymer columns may be spaced apart from each other by a predetermined interval. In one embodiment of the present invention, the amount of the two or more polymer columns clustered is 30 vol% or less, preferably 20 vol% or less, and more preferably 10 vol% or less, based on 100 vol% of the total polymer columns. If the polymer columns are excessively clustered, it may cause non-uniformity of resistance in the separation membrane. Therefore, in terms of increasing the uniformity of resistance, it is preferable that the amount of the polymer columns forming the cluster is 10 vol% or less based on 100 vol% of the total polymer columns.

[0110]

[0111] In one embodiment of the present invention, preferably, the polymer columns are distributed in a sea-like manner in the inorganic coating layer at a predetermined interval without being in direct contact with other polymer columns.

[0112]

[0113] In one embodiment of the present invention, the separation membrane may have one or more polymer columns higher than the height of the inorganic particle filling portion when not artificially pressurized after manufacture. That is, they may protrude from the surface of the inorganic particle filling portion. In the inorganic coating layer, a plurality of polymer columns are embedded so as to be exposed or protrude outside the surface of the inorganic coating layer, and among these, the protrusion height (T) of some of the polymer columns p ) can exceed 1㎛. For example, T pThe polymer columns may be greater than 1 ㎛ and less than or equal to 10 ㎛, for example, less than or equal to 7 ㎛, less than or equal to 5 ㎛, or less than or equal to 3 ㎛. In addition, some of the polymer columns exposed to or protruding from the surface of the inorganic coating layer may be in contact with the porous substrate. Here, the protrusion of the polymer columns outside the surface of the inorganic coating layer means that the inorganic particle filling portion (T) of the inorganic coating layer i ) compared to the height of the polymer column (T c ) means that it has a higher height than the inorganic particle filling part.

[0114]

[0115] In one embodiment of the present invention, the average pore size of the inorganic coating layer may be 20 nm to 1,000 nm. In one embodiment of the present invention, the pore size may be measured for the inorganic particle filling portion. Within the above range, the average pore size of the inorganic coating layer may be 800 nm or less, or 500 nm or less, and independently or in combination may be 20 nm or more, 50 nm or more, or 100 nm or more. For example, the average pore size of the inorganic coating layer may be 20 nm to 800 nm. The pore size may be calculated from shape analysis using an SEM image. If the pore size is smaller than the above range, the pores are likely to be blocked due to expansion of the binder resin in the coating layer, and if the pore size is outside the above range, it is difficult to function as an insulating film, and there is a problem that the self-discharge characteristics deteriorate after manufacturing a secondary battery.

[0116]

[0117] In one embodiment of the present invention, the porosity of the inorganic coating layer (porosity in a state where the polymer column is included) is preferably 30 vol% to 80 vol%. The porosity can be appropriately controlled within the above range. For example, the porosity may be 35 vol% or more, or 40 vol% or more, or 45 vol or more. Alternatively, the porosity may be 75 vol% or less, or 70 vol% or less, or 65 vol% or less. If the porosity is 30% or more, it is advantageous in terms of lithium ion permeability, and if the porosity is 80% or less, the surface opening ratio is not too high, which is suitable for securing adhesion between the separator and the electrode.

[0118]

[0119] polymer column

[0120] The polymer column may comprise a polymer resin in an amount of 90 wt% or more, 95 wt% or more, or 99 wt% or more, based on 100 wt% of the polymer column. Preferably, the polymer column may be formed of a polymer resin. In addition, the polymer column has adhesive properties, and may adhere to a battery material adjacent to the polymer column, such as an inorganic particle or a porous substrate.

[0121] In the present invention, the polymer column may not have open cell-type pores in its body. It is preferable that the polymer column does not have open cell-type pores, so that a fluid such as a gas or liquid does not flow through the polymer column body.

[0122] As described above, at least a portion of the one or more polymer columns may be exposed or protruding from the surface of the inorganic coating layer and another portion may be in contact with the surface of the porous substrate.

[0123] In one embodiment of the present invention, D of the polymer column 10 Silver D 50 It can be more than 30% of D90 Silver D 50 may be less than 200% of the D of the polymer column, together with or independently of this. 50 Silver inorganic particles D 50 The contrast can be twice or more.

[0124] In one embodiment of the present invention, D of the polymer column 50 silver It may be about 2.5㎛ to 7.5㎛, or 3.0㎛ to 7.0㎛, preferably D 50 This may have a range of 3.5㎛ to 6.5㎛ or 4.0㎛ to 6.0㎛. D of the polymer column 50 It reflects the state before the membrane is pressurized, preferably before slurry preparation.

[0125]

[0126] Meanwhile, in the present invention, it is preferable that the polymer column has a storage modulus (G') at room temperature of 100 Pa or more and 3,500 Pa or less in order to prevent flattening due to pressure during the first compression. For example, the storage modulus may be 500 Pa or more, 700 Pa or more, 1,000 Pa or more, 1,200 Pa or more, 1,500 Pa or more, or 2,000 Pa or more within the above range. Preferably, the storage modulus may be for a material forming the polymer column. In one embodiment of the present invention, the room temperature may be in the range of 20°C to 25°C. In one embodiment of the present invention, the polymer column may have a storage modulus at a high temperature (50°C to 80°C or 60°C to 80°C) in the range of 0.1 Pa to 100 Pa. For example, within the above range, the high temperature storage modulus may be 0.5 Pa or more, 1.0 Pa or more, 2.0 Pa or more, 5.0 Pa or more, 10.0 Pa or more, or 50 Pa or more.

[0127]

[0128] Additionally, more preferably, the polymer column may have at least one tan δ peak in the range of 45°C to 80°C as measured by a Dynamic Mechanical Analyzer (ARES-G2, TA Instrument).

[0129] In one embodiment of the present invention, the storage modulus and tan δ peak can be measured using a rheological property measuring equipment (Dynamic Mechanical Analyzer (DMA), ARES-G2, TA Instrument). In a specific embodiment, the storage modulus can be confirmed by performing a temperature sweep test at a temperature condition of -60°C to 80°C and a frequency of 1.0 rad / s. In addition, the tan δ peak can be calculated by calculating the ratio of the loss modulus to the storage modulus from the measured elastic moduli (storage modulus and loss modulus). In addition, the slope of the storage modulus (Storage modulus, G') at 45°C and the storage modulus (Storage modulus, G') at 70°C can be measured through the DMA.

[0130]

[0131] In this respect, the separator of the present invention may have a first compression ratio of 25% or less, 20% or less, 15% or less, or 10% or less by a first compression under a pressurized condition of 3.0 MPa to 4.0 MPa, and 55°C to 65°C. Meanwhile, the first compression ratio may be 5% or more, or 10% or more. For example, the first compression ratio may be 15% to 25% or 20% to 25%. The first compression ratio is a value calculated by [Formula 2] below, and refers to a compression ratio (dry compression ratio) when the separator is first compressed before coming into contact with the electrolyte after manufacturing.

[0132]

[0133] [Formula 2]

[0134] First compression ratio (%) = {(Initial thickness before first compression - Thickness after first compression) / (Thickness before first compression)} x 100.

[0135]

[0136] Height (T) of the inorganic coating layer after the first compression under the above conditions c ) is 1.1 x T i < T c < 1.5 x T i Specifically, the protrusion height of the polymer column after the first compression is greater than 1 μm, and the protrusion height is not flattened to 1 μm or less.

[0137] The above first compression condition is typically based on the lamination process conditions of the electrode and separator for manufacturing an electrode assembly. According to this compression ratio, the electrode and separator are not completely in close contact during the lamination process, but a gap occurs, and the gap can serve as an electrolyte impregnation path through which the electrolyte flows into the electrode assembly when the electrode assembly is impregnated with the electrolyte. Meanwhile, when the compression ratio is within the above range, the separator can implement the adhesive strength required for the manufacturing process, such as the electrode assembly manufacturing and storage before electrolyte impregnation. For example, when manufacturing an electrode assembly by a roll-to-roll continuous process, the adhesive strength can be secured at a level that prevents meandering of the electrode and separator.

[0138]

[0139] Meanwhile, in one embodiment of the present invention, the separator of the present invention has a second compression ratio of 30% or more by a second compression under a pressurizing condition of 0.5 MPa to 1.5 MPa and 35°C to 85°C. The pressurizing temperature can be appropriately adjusted within the above range depending on the pressure range applied. The pressurizing temperature can be, for example, 75°C or less, 65°C or less, 55°C or less, or 45°C or less. The second compression ratio can be calculated by [Formula 3] below. In one embodiment of the present invention, the second compression ratio can be a compression ratio (wet compression ratio) in a state where the separator is immersed in an electrolyte for 5 minutes or more after the first compression and the electrolyte on the surface is removed and pressurized under the above conditions. In one embodiment of the present invention, the electrolyte applicable when measuring the second compression ratio can all refer to the contents of the electrolyte described below.

[0140]

[0141] [Formula 3]

[0142] Second compression ratio (%) = {(Initial thickness before first compression - Thickness after second compression) / (Initial thickness before first compression)} x 100.

[0143]

[0144] After the second compression under the above conditions, the thickness of the inorganic coating layer (T c ) is 1.0 x T i < T ≤ 1.1 x T i, and after the second compression, the protruding thickness of the polymer column can be flattened to 1㎛ or less. This property is advantageous in strengthening the adhesion between the electrode and the separator during battery manufacturing and ensuring that the electrode and the separator are in close contact to prevent a gap from occurring. That is, the polymer column can exhibit more flexible (softening) properties after being impregnated with an electrolyte. In addition, deformation of the polymer column can be implemented under milder conditions than during dry compression. Meanwhile, the compression time during the first and second compressions can be controlled in the range of 1 second to 60 seconds.

[0145] In the present specification, the term "flattening" means that the deviation between the thickness (Ti) of the inorganic particle filling portion and the height (Tc) of the polymer column is 1 μm or less. In one embodiment of the present invention, the height of the polymer column may be based on the highest height among the polymer columns. Referring to FIG. 1, the T c refers to the total height of the inorganic coating layer (one side), and is based on the highest part of the inorganic coating layer from the surface of the porous substrate. In the present invention, the T c may be the height of the highest protruding polymer column. Meanwhile, in the present invention, the T p It is based on the highest part of the inorganic coating layer from the inorganic particle filling part.

[0146]

[0147] That is, when the separator according to the present invention is applied to battery manufacturing, the thickness of the inorganic particle filling part after lamination of the electrode and the separator is polymer column D 50 Smaller is preferable.

[0148]

[0149] Meanwhile, the flattened polymer column may have a larger planar surface area than before pressurization. In this case, the planar major axis length of the polymer column after flattening is D of the polymer column before flattening.50 It is desirable that it be less than 10 times.

[0150]

[0151] In one embodiment of the present invention, in terms of securing a predetermined second compression ratio, it is preferable that the material forming the polymer column has a solubility in an organic solvent or electrolyte of 15% to 70% and / or an uptake of an electrolyte of 30% or more.

[0152] In a specific embodiment, the polymer column may be dissolved in THF (Tetrahydrofuran) for 1 to 48 hours, and then the dissolved amount (weight) may be 15% to 70%, preferably 20% to 60%, and more preferably 25% or more and 50% or less. When the solubility exists in the above range, the increase in resistance due to binder dissolution within the battery can be prevented, while the electrolyte can be easily absorbed during secondary compression, thereby securing the compression ratio. In the present invention, the solubility can be calculated through the following [Formula 5].

[0153]

[0154] [Formula 5]

[0155] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / Weight measured before immersion} x 100

[0156]

[0157] Meanwhile, the electrolyte absorption rate can be calculated by [Formula 6] below.

[0158]

[0159] [Formula 6]

[0160] Electrolyte uptake (%) = {(Total weight of polymer column after electrolyte impregnation - Weight of polymer column before electrolyte impregnation) / (Weight of polymer column before electrolyte impregnation)} x 100.

[0161]

[0162] In addition, when the above properties are satisfied, it is possible to prevent the polymer column from dissolving and losing adhesiveness after liquid electrolyte injection, or the viscosity of the liquid electrolyte from increasing due to the dissolved component, thereby preventing the resistance of the lithium secondary battery from increasing.

[0163] The above electrolyte absorption rate is calculated by immersing a polymer column of a predetermined size in an electrolyte for several minutes to an hour, for example, 5 minutes, then taking it out, removing the electrolyte remaining on the surface, and measuring the weight. The electrolyte may be, for example, 1 MLiPF6 in an ethylene carbonate / ethyl methyl carbonate (EC / EMC, volume ratio 30:70) electrolyte, but is not limited thereto, and any electrolyte that can be applied as an electrolyte for a lithium-ion secondary battery may be used without limitation.

[0164] However, there is a concern that after the liquid electrolyte is injected, the polymer column may dissolve and lose its adhesiveness, or the dissolved components may increase the viscosity of the liquid electrolyte, thereby increasing the resistance of the lithium secondary battery. Therefore, the material forming the polymer column needs to have its solubility in the electrolyte appropriately adjusted through surface crosslinking as described above.

[0165]

[0166] Meanwhile, in the present invention, the pressurization may be performed for a period ranging from several seconds to several minutes. For example, it may be within 60 seconds or within 30 seconds. Since the separation membrane according to the present invention can be flattened in a short period of time, process efficiency can be improved.

[0167]

[0168] In one embodiment of the present invention, the polymer column preferably includes a material having the above-described characteristics, being non-reactive within a lithium secondary battery, and capable of imparting bonding strength between a separator and an electrode. Considering these aspects, the polymer column may include, for example, 10 wt% or more, 30 wt% or more, 50 wt% or more, 70 wt% or more, or 90 wt% or more of the acrylic polymer relative to 100 wt% of the polymer column. In the present invention, the polymer column may include an acrylic polymer. For example, the acrylic polymer is an acrylate series acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, pentyl acrylate, hexylacrylate, heptyl acrylate, octylacrylate, 2-ethylhexylacrylate, nonylacrylate, decylacrylate, lauryl acrylate, n-tetradecylacrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, It may include one or more repeating units of 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. However, it is not limited thereto. Meanwhile, in a specific embodiment, one or more hydrogens in the unit may be substituted with another substituent. In one embodiment of the present invention, the acrylic polymer may include the above-described repeating unit in an amount of 30 wt% or more, 50 wt% or more, 70 wt% or more, or 90 wt% or more, based on 100 wt% of the acrylic polymer.

[0169] Meanwhile, in one embodiment of the present invention, the acrylic polymer may have a weight average molecular weight of about 20,000 to 800,000. In one embodiment of the present invention, one or more polymer columns may have an area (a) of a cross-section of a polymer column confirmed in a cross-section at the lower 5% from the lowest part of the inorganic coating layer toward the surface, and an area (b) of a cross-section of a polymer column confirmed in a cross-section at the upper 5% from the top of the inorganic coating layer toward the bottom, wherein the area (a) is greater than the area (a). This characteristic of the polymer column may apply to a case where the polymer column protrudes from the surface of the inorganic coating layer and / or is flattened by pressurization. Preferably, the characteristic may be confirmed in a shape of the polymer column after it is flattened after protrusion.

[0170]

[0171] Together with or independently of this, one or more polymer columns may have a diameter (a) of the lower portion of the polymer column that is shorter than a diameter (b) of the upper portion of the column in a cross-section of the polymer column as seen in the vertical cross-section of the inorganic coating layer. In one embodiment, the ratio of the upper diameter (b) to the lower diameter (a) may be greater than 1 and less than or equal to 20, or from 1.2 to 20, or from 1.5 to 20, or from 2 to 20. This characteristic of the polymer column may apply when the polymer column protrudes from the surface of the inorganic coating layer and / or when it is flattened by pressing. Preferably, the characteristic may be found in the shape of the polymer column after being flattened. In one embodiment of the present invention, the upper diameter refers to the diameter at the upper 5% point from the top of the polymer column toward the bottom, and the lower diameter refers to the diameter at the lower 5% point from the bottommost portion of the polymer column toward the top.

[0172]

[0173] In one embodiment of the present invention, the height of the polymer column, the length of the diameter of the polymer column, and / or the size of the cross-section can be calculated from an SEM image of a horizontal or vertical cross-section of the membrane. FIG. 2 shows an SEM image of the surface of the membrane of Example 1 of the present invention, and the dimensions of each component can be confirmed. Another method of utilizing the SEM image is to divide the SEM image into gray levels and measure an area corresponding to a specific gray level corresponding to the polymer column. The gray level refers to a brightness value for a plurality of pixels included in the SEM image. For example, in an SEM image of 256 gray levels with steps of 0 to 255, the brightness value range can be a value of 0 to 255. In a specific embodiment of the present invention, the polymer column can have a gray level of 10 to 50, and the inorganic particles can have a gray level of 160 to 220. Accordingly, the region of the polymer column can be set and defined from pixels having 10 to 50 gray levels in the SEM image of an arbitrary cross-section of the membrane, and its length and area can be calculated. In the present invention, the electrode cross-section SEM image can be obtained by performing EDS mapping of the components using an energy dispersive X-ray spectroscopy (EDS) detector of a scanning electron microscope (SEM) equipment on a cross-section of an electrode obtained by argon ion milling, and then performing image processing.

[0174]

[0175] In another specific embodiment of the present invention, the diameter or area of ​​the polymer column can be calculated by three-dimensionally modeling the separation membrane and / or the inorganic coating layer and then obtaining an arbitrary cross-section therefrom.

[0176]

[0177] Inorganic particle filling section

[0178] The space between the polymer columns in the inorganic coating layer of the above-described separation membrane may be filled with inorganic particles. In the present specification, the portion filled with inorganic particles is referred to as an “inorganic particle filling portion.” The inorganic filling portion may further include a binder resin to secure adhesion between the inorganic particles and between the inorganic particles and the porous substrate. The inorganic particle filling portion has pores resulting from an interstitial volume formed between adjacent inorganic particles. Due to the pores, the inorganic coating layer may have a porous structure having a predetermined porosity, and gas or liquid may pass from one side to the other side. The inorganic particles and the polymer columns may be bonded by the adhesive properties of the polymer columns or may be bonded via a binder resin.

[0179]

[0180] In one embodiment of the present invention, before flattening the separation membrane, the thickness (T) of the inorganic particle filling portion i ) is the D of the polymer column 50 may be less than 85% of the total. For example, it may range from 5% to 40%. In a specific embodiment, T i The T may be 1.0 μm to 5.0 μm and may be appropriately adjusted within the above range. The T may be, for example, 4 μm or less, 3 μm or less, or 2 μm or less. The T iThe thickness is preferably 1.0 μm or more, and within the above numerical range, the adhesion to the electrode is excellent, and as a result, the cell strength of the battery is increased. On the other hand, if the thickness is 5.0 μm or less, it is advantageous in terms of cycle characteristics and resistance characteristics of the battery. When the inorganic coating layer is disposed on both sides of the porous substrate, the thickness of the inorganic particle filling portion refers to a value measured for the inorganic coating layer disposed on either side.

[0181]

[0182] In one embodiment of the present invention, the height (thickness, T) of the inorganic particle filling portion i ) can be obtained by cutting a cross-section of a membrane specimen, observing it through an SEM, and then measuring the thickness of two or more arbitrary points in an area where no polymer column is located, and taking the average value as the height. If the thickness of four or more points is measured, the lowest and / or highest values ​​can be excluded, and the average value of the remaining values ​​can be taken.

[0183] Meanwhile, in one embodiment of the present invention, the height of the inorganic particle-filled portion may tend to increase as it gets closer to the polymer column in the inorganic particle-filled portion. This tendency may be more noticeable with respect to the periphery of the polymer column. That is, the height of the outer portion of the periphery may gradually increase from any point of the inorganic particle-filled portion toward the polymer column, and may relatively rapidly increase as it goes from the boundary of the periphery toward the polymer column. In one embodiment of the present invention, the periphery may mean a portion having a width of about 2 μm from the boundary between the inorganic particle-filled portion and the polymer column toward the inorganic particle-filled portion.

[0184]

[0185] inorganic particles

[0186] In a specific embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as they do not undergo oxidation and / or reduction reactions within the operating voltage range of the applied electrochemical device (e.g., 0 to 5 V based on Li / Li+). In particular, when inorganic particles having a high dielectric constant are used as the inorganic particles, they can contribute to increasing the degree of dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte.

[0187] For the reasons mentioned above, it is preferable that the inorganic particles include high-k inorganic particles having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3(PZT), b 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC and TiO2 or mixtures thereof.

[0188] In addition, as the inorganic particles, inorganic particles having lithium ion transfer capability, i.e., inorganic particles containing lithium element but having the function of transferring lithium ions without storing lithium, can be used. Non-limiting examples of inorganic particles having lithium ion transfer capability include lithium phosphate (Li3PO4), lithium titanium phosphate (LixTiy(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), 14Li2O-9Al2O3-38TiO2-39P2O5, etc. (LiAlTiP) x O y Series glass (0 <x < 4, 0 < y < 13), 리튬란탄티타네이트(Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 Lithium germanium thiophosphate (Li) such as S4 x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li 3 N ), etc. x N y , 0 < x <4, 0 < y < 2), SiS2 series glass (Li) such as Li3PO4-Li2S-SiS2 x Si y S z , 0 < x < 3, 0 <y < 2, 0 < z < 4), LiI-Li2S-P2S5등과 같은 P2S5계열 glass(Li x P y S z , 0 < x < 3, 0< y < 3, 0 < z < 7) or mixtures thereof.

[0189]

[0190] In addition, the average particle diameter of the inorganic particles is not particularly limited, but is preferably in the range of 0.1 μm to 1.5 μm for forming a coating layer of uniform thickness and having an appropriate porosity. If it is less than 0.1 μm, dispersibility may be reduced, and if it exceeds 1.5 μm, the thickness of the formed coating layer may increase. According to a non-limiting embodiment of the present invention, the diameter (D50) of the inorganic particles may be appropriately adjusted in the range of 0.1 μm to 1.5 μm, and may have, for example, a range of 200 nm to 1 μm.

[0191]

[0192] binder resin

[0193] Additionally, as described above, the inorganic coating layer may further include a binder resin to supplement the bonding force. The binder resin may be included in an amount of about 10 wt% or less, or 5 wt% or 1 wt% or less, or 0.5 wt% or less, relative to 100 wt% of the inorganic coating layer.

[0194] In one embodiment of the present invention, the binder resin may include a PVdF-based polymer resin. The PVdF-based polymer resin may include at least one of a homopolymer of vinylidene fluoride (i.e., polyvinylidene fluoride), a copolymer of a monomer copolymerizable with vinylidene fluoride, and a mixture thereof. In one embodiment of the present invention, the monomer may include, for example, a fluorinated monomer and / or a chlorinated monomer. Non-limiting examples of the fluorinated monomer include vinyl fluoride; trifluoroethylene (TrFE); chlorofluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkylvinyl) ethers such as perfluoro(methylvinyl) ether (PMVE), perfluoro(ethylvinyl) ether (PEVE), and perfluoro(propylvinyl) ether (PPVE); perfluoro(1,3-dioxole); and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD), and more than one of these may be included.

[0195] Together with or independently of this, a (meth)acrylic polymer resin may further be included as a binder resin. The above (meth)acrylic polymer contains a (meth)acrylic acid ester as a monomer, and non-limiting examples thereof include a (meth)acrylic polymer containing butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, n-oxyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, and tetradecyl (meth)acrylate as monomers.

[0196]

[0197] In addition, in one embodiment of the present invention, the inorganic coating layer may further include an additive such as a dispersant and / or a thickener in a range of 1 to 3 wt% based on 100 wt% of the inorganic coating layer. In one embodiment of the present invention, the additive may be selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), hydroxy ethyl cellulose (HEC), hydroxy propyl cellulose (HPC), ethylhydroxy ethyl cellulose (EHEC), methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxy alkyl methyl cellulose, and cyanoethylene polyvinyl alcohol.

[0198]

[0199] Membrane manufacturing method

[0200] Next, a method for manufacturing the membrane of the present invention will be described. However, the following description is for one embodiment of manufacturing the present invention and is not particularly limited thereto.

[0201] Specifically, a mixture is first prepared by adding inorganic particles to an appropriate solvent. Next, polymer particles for polymer columns are added to the mixture to prepare a slurry for an inorganic coating layer. Next, the slurry is applied to a porous substrate and dried.

[0202] In one embodiment of the present invention, when the inorganic coating layer further comprises a binder resin, the binder resin may be dissolved in a solvent to prepare a polymer solution, and then inorganic particles and polymer particles for polymer columns may be sequentially or simultaneously added to the polymer solution to prepare a slurry for the inorganic coating layer. The binder resin is preferably a water-soluble binder resin.

[0203] Thereafter, the obtained separator can be dried to form an inorganic coating layer integrally on the porous substrate. At this time, the drying temperature of the separator is preferably set to a temperature of +20°C or lower than the glass transition temperature of the polymer column material to prevent deformation of the polymer column.

[0204]

[0205] In the production of the above slurry, water or an aqueous solvent containing water may be used as the solvent. In addition, when there are limitations on drying speed and temperature, methanol, ethanol, isopropyl alcohol, etc., which have a lower boiling point than water, may be used as a co-solvent.

[0206]

[0207] The above slurry can be applied using conventional coating methods such as a Meyer bar, die coater, reverse roll coater, or gravure coater. Meanwhile, the drying can be performed using a conventional method for removing the solvent. Examples of the drying method include, but are not limited to, natural drying, air drying, warm air or hot air drying, high-temperature drying, and convection drying.

[0208]

[0209] Meanwhile, in addition to the above-described manufacturing method, any manufacturing method that can achieve the above-described membrane structure can be applied without limitation.

[0210]

[0211] Meanwhile, the present invention provides a secondary battery including the separator. The battery includes a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode, wherein the separator is a separator having the characteristics described above.

[0212]

[0213] In the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn 2-x M x A lithium manganese composite oxide represented by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0214]

[0215] In the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes carbon such as lithium metal oxide, non-graphitizable carbon, and graphite carbon as the negative electrode active material; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0216]

[0217] In a specific embodiment of the present invention, the conductive material may be, for example, one selected from the group consisting of graphite, carbon black, carbon fibers or metal fibers, metal powders, conductive whiskers, conductive metal oxides, activated carbon, and polyphenylene derivatives, or a mixture of two or more conductive materials thereof. More specifically, the conductive material may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more conductive materials thereof.

[0218]

[0219] The above-mentioned current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0220]

[0221] As the above binder resin, a polymer commonly used in electrodes in the art can be used. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples thereof include, but are not limited to, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0222]

[0223] Battery manufacturing

[0224] The battery manufacturing method of the present invention is characterized in that a first compression is performed during the manufacturing of the electrode assembly or before impregnation with an electrolyte (dry compression), and then a second compression is performed after the electrode assembly is impregnated with an electrolyte and the polymer column is softened by the electrolyte.

[0225] First, a laminate including at least one anode, at least one separator, and at least one cathode is prepared. The laminate is laminated at least once with a separator interposed between the anode and the cathode. The electrodes and separators, etc., constituting the laminate are not in close contact with each other but are simply stacked. Thereafter, the laminate is pressed at a strength of 3.0 MPa to 4.0 MPa under temperature conditions of 55°C to 65°C to manufacture a first electrode assembly. Here, the polymer columns in the separator are not completely flattened. In this way, since the polymer columns are not completely flattened before electrolyte impregnation and a certain distance is maintained between the separator and the electrode, the electrolyte can easily flow into the first electrode assembly. That is, there is an advantage of securing a movement path of the electrolyte.

[0226] Thereafter, the first electrode assembly is impregnated with an electrolyte, and a second compression is performed thereafter. The second compression includes a step of applying a pressure of 0.5 MPa to 1.5 MPa to the impregnated first electrode assembly. Pressure is applied to the impregnated first electrode assembly so that the separator and the positive electrode and / or the separator and the negative electrode are in close contact with each other, and it is preferable that the pressure application is performed under a temperature condition of 35°C to 85°C. After the electrode assembly is sufficiently impregnated with the electrolyte in this way, the second compression is performed so that the electrode and the separator are in close contact with each other. Therefore, there is an advantage in that the wettability of the electrode assembly is improved. Meanwhile, the step of impregnating the first electrode assembly with the electrolyte includes housing the first electrode assembly in a battery case, and an aging step may be further performed after the impregnation and before the pressure application. The aging may preferably be performed within a range of 20°C to 75°C.

[0227]

[0228] In the present invention, the electrolyte is A + B - As a salt with the same structure as A + is Li + ,Na + ,K + B containing an ion composed of an alkali metal cation or a combination thereof; - is PF6 - ,BF4 - ,Cl - ,Br - ,I - ,ClO4 - ,AsF6 - ,CH3CO2 - ,CF3SO3 - ,N(CF3SO2)2 - ,C(CF2SO2)3 -Salts containing anions such as or combinations thereof are dissolved or dissociated in organic solvents including propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone (g-butyrolactone), ester compounds, and mixtures of one or more selected from these, but are not limited thereto.

[0229]

[0230] Meanwhile, in a specific embodiment of the present invention, the organic solvent may include an ester compound. Preferably, the ester compound may be at least 30 wt%, at least 50 wt%, at least 60 wt%, or at least 65 wt% relative to 100 wt% of the organic solvent.

[0231] In a specific embodiment of the present invention, the ester compound may include at least one selected from the group consisting of isobutyl propionate, isoamyl propionate, isobutyl butyrate, isopropyl propionate, methylpropionate, ethylpropionate, propylpropionate, butylpropionate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, and butyl butyrate.

[0232]

[0233] In addition, the present invention provides a battery module including a battery including the electrode assembly as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0234] Hereinafter, the present invention will be described in detail with examples to specifically illustrate it. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention should not be construed as being limited to the examples described below. These examples are provided to more fully explain the present invention to those of average skill in the art.

[0235]

[0236] Example

[0237] Membrane thickness measurement

[0238] In the examples and comparative examples, the thickness of the separator was determined by cutting a cross-section of the separator sample and observing it through an SEM. The thickness of the thickest point was determined as the thickness of the separator. The thickness of the separator was measured after the first and second compressions, and the compression ratio was calculated, which is summarized and shown in Table 2. Meanwhile, the thickness of the inorganic particle filling part was determined as the average value of the values ​​measured at three random points.

[0239]

[0240] Measurement of storage modulus of polymer columns

[0241] A 40 mm x 60 mm sample was fabricated using a polymer material to be used as a polymer column in comparative examples and examples. The thickness of the sample was 1 mm. The elastic modulus was measured for the sample. The storage modulus was measured using a rheological property measuring equipment (Dynamic Mechanical Analyzer (DMA), ARES-G2, TA Instrument). The storage modulus was confirmed by conducting a temperature sweep test at a temperature condition of -60°C to 80°C and a frequency of 1.0 rad / s. This is summarized and shown in Table 1 below. In addition, the storage modulus and loss modulus were confirmed in the measurement, and through this, the tan δ peak was confirmed.

[0242]

[0243] Solubility measurement of polymer columns

[0244] A 0.3-g sample was prepared using the polymer material to be used as the polymer column in the comparative examples and examples. The sample was placed in an 80-mesh mesh bag and dissolved in THF (Tetrahydrofuran) for 24 hours. The residual weight was compared to the initial weight. The solubility was calculated based on [Equation 1] below. This is summarized and presented in Table 1 below.

[0245]

[0246] [Formula 1]

[0247] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0248]

[0249] Solubility (%)D 50(㎛) Storage modulus (G') (Pa, 25℃) Storage modulus (G') (Pa, 60℃) G' (60℃) / G' (room temperature, ℃) tan δ peak (℃, 45 to 80℃) Tg (℃) Acrylic polymer A100 25% 3.84 1245.42 46.17 0.03 966 9.19 56.1 Acrylic polymer A24 (comparative example) 19% 4.2 22,623 3.3 0.00 159.647.2 Acrylic polymer A25 (comparative example) 82% 3.9 2 25.2 1.8 0.07 262.84 1.1

[0250]

[0251] Example 1

[0252] Inorganic particles (Al2O3, D 50 (About 0.6㎛), acrylic emulsion (Toyo, CSB-130) as binder resin, carboxyl methyl cellulose (Daicel, Daicel1220) were added to a water:ethanol 95:5 solution at a ratio of 96:2:2 and dispersed using a bead mill to obtain a mixture. Acrylic polymer A100 was added to the mixture and stirred to obtain a dispersion slurry. The solubility of the mixed polymer column was 25% and the storage modulus at room temperature was 1,245 Pa. The concentration of solids in the dispersion slurry was 30 wt%. The content of polymer particles for the polymer column in the mixture was about 20 parts by weight relative to 100 parts by weight of inorganic particles. The dispersion slurry was applied to a porous substrate (Senior SW807I, thickness 7㎛) by a microgravure coating method and dried at a temperature of 80℃ to obtain a separation membrane. In addition, the opposite side was coated and dried in the same manner to obtain a double-coated separator. In the separator, the loading amount (one side) of the inorganic coating layer based on one side of the porous substrate was 6.2 g / m 2 It was.

[0253] The obtained membrane was then subjected to a first compression using a hot press at 2.5 MPa and 60°C for 20 seconds, and the compressibility of the membrane was confirmed. Figure 3 shows an SEM image of the surface of the obtained membrane after the first compression. Referring to this, it was confirmed that the polymer columns were exposed on the surface of the inorganic coating layer, and that a number of polymer columns were distributed in an island-like shape at a predetermined interval. In addition, it was confirmed that the protruding portions of the polymer columns were not flattened.

[0254] Next, a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 7:3 was prepared, and 1 M LiPF6 was added thereto to prepare an electrolyte. After the first compression, the separator was immersed in the electrolyte and left for about 5 minutes. Thereafter, the immersed separator was taken out, and the remaining electrolyte was dried. A second compression was performed by applying pressure at 1.0 MPa and 60°C for 20 seconds using a hot press, and the compression ratio of the separator was confirmed. Referring to Table 2 below, the thickness of the separator after the second compression was 10.1 μm, which was confirmed to be reduced by more than 30% compared to the initial thickness of the separator before compression.

[0255]

[0256] Comparative Example 1

[0257] Inorganic particles (Al2O3, D 50 About 0.6㎛), acrylic emulsion (Toyo, CSB-130) and carboxyl methyl cellulose (Daicel, Daicel1220) as binder resin were added in a 96:2:2 ratio to a 95:5 water:ethanol solution and a dispersion process using a bead mill was performed to obtain a mixture. An acrylic polymer (A24, D) was added to the mixture. 504.22㎛) was added and stirred to obtain a dispersion slurry. The concentration of solids in the dispersion slurry was 30 wt%. The content of polymer particles for polymer columns in the mixture was about 20 parts by weight based on 100 parts by weight of inorganic particles. The dispersion slurry was applied to a porous substrate (Senior SW807I, thickness 7㎛) by a microgravure coating method and dried at a temperature of 80℃ to obtain a separator. In addition, the opposite side was coated and dried in the same manner to obtain a double-coated separator. In the separator, the loading amount (one side) of the inorganic coating layer based on one side of the porous substrate was 6.1 g / m. 2 It was.

[0258] The obtained membrane was then subjected to a first compression using a hot press at 2.5 MPa and 60°C for 20 seconds, and the compressibility of the membrane was confirmed. Figure 5 shows an SEM image of the surface of the obtained membrane after the first compression. Referring to this, it was confirmed that the polymer columns were exposed on the surface of the inorganic coating layer, and that a number of polymer columns were distributed in an island-like shape at a predetermined interval. In addition, it was confirmed that all protruding portions of the polymer columns were flattened.

[0259] Next, the second compression ratio was confirmed using the same method as Example 1. The second compression ratio was 30% or more, but the thickness was already significantly reduced during the first compression, and the amount of reduction due to the second compression after the first compression was confirmed to be minimal.

[0260]

[0261] Comparative Example 2

[0262] Inorganic particles (Al2O3, D 50About 0.6㎛), acrylic emulsion (Toyo, CSB-130) and carboxyl methyl cellulose (Daicel, Daicel1220) as binder resin were added in a 96:2:2 ratio to a 95:5 water:ethanol solution and a dispersion process using a bead mill was performed to obtain a mixture. An acrylic polymer (A25, D) was added to the mixture. 50 3.92㎛) was added and stirred to obtain a dispersion slurry. The concentration of solids in the dispersion slurry was 30 wt%. The content of polymer particles for polymer columns in the mixture was about 20 parts by weight based on 100 parts by weight of inorganic particles. The dispersion slurry was applied to a porous substrate (Senior SW807I, thickness 7㎛) by a microgravure coating method and dried at a temperature of 80℃ to obtain a separator. In addition, the opposite side was coated and dried in the same manner to obtain a double-coated separator. In the separator, the loading amount (one side) of the inorganic coating layer based on one side of the porous substrate was 6.4 g / m. 2 It was.

[0263] The obtained membrane was then subjected to a first compression test using a hot press at 2.5 MPa and 60°C for 20 seconds, and the compressibility of the membrane was confirmed. Furthermore, surface observation revealed that polymer columns were exposed on the surface of the inorganic coating layer, and that a number of polymer columns were distributed in a sea-island configuration at predetermined intervals. Furthermore, it was confirmed that all protruding portions of the polymer columns were flattened.

[0264] Next, the second compression ratio was confirmed using the same method as Example 1. The second compression ratio was 30% or more, but as in Comparative Example 1, the thickness was already significantly reduced during the first compression, and the amount of reduction due to the second compression after the first compression was confirmed to be minimal.

[0265]

[0266] Comparative Example 3

[0267] Inorganic particles (Al2O3, D50 approximately 0.6㎛), acrylic emulsion as binder resin (Toyo, CSB-130), and carboxyl methyl cellulose (Daicel, Daicel1220) were added to a water:ethanol 95:5 solution at a ratio of 96:2:2 and stirred to obtain a mixture. The mixture was applied to a porous substrate (Senior SW807I, thickness 7㎛) by a microgravure coating method and dried at a temperature of 80℃. Meanwhile, the obtained separator was compressed for the first time at 2.5 MPa and 60℃ for 20 seconds using a hot press to flatten the surface. Next, the second compression ratio was confirmed in the same manner as in Example 1. It was confirmed that the compression ratio by the first and second compressions in Comparative Example 3 was significantly lower than that of Example 1.

[0268]

[0269] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Membrane thickness (㎛) (first measurement) 15.5 15.2 15.6 12.8 Amount of inorganic coating layer applied (g / m 2 )(Loading amount, based on one side)6.26.16.46.0Organic particle coverage (%)21.522.120.6n / aCathode / Separator Dry adhesion (gf / 25mm)131516n / aSeparator thickness after first compression (㎛)12.210.510.812.5First compression ratio (Dry compression ratio) (%)21.330.930.73.3Separator thickness after second compression (㎛)10.110.310.7n / aSecond compression ratio (Wet compression ratio) (%)34.832.231.4n / aWhether Li plating occurs after battery assembly OKNGNGn / a

[0270]

[0271] Manufacturing of anodes

[0272] LiCoO as a cathode active material 　2, carbon black as a conductive agent and polyvinylidene fluoride (PVdF) as a binder were added to N-methylpyrrolidone (NMP) as a solvent at a weight ratio of 96:2:2 to prepare a cathode active material slurry. The cathode active material slurry was coated on a sheet-shaped aluminum current collector and dried to obtain a final cathode loading of 3.8 mAh / cm. 2 To achieve this, a positive electrode active material layer was formed.

[0273]

[0274] Manufacturing of cathode

[0275] Artificial graphite as a negative active material, carbon black as a conductive agent, carboxymethyl cellulose as a dispersant, and styrene butadiene emulsion as a binder were mixed in a weight ratio of 96:0.5:1.5:2.0, respectively, and added to water as a solvent to prepare a negative electrode slurry. The negative electrode slurry was prepared at a capacity of 4.0 mAh / cm 2 A negative electrode having a negative active material layer formed by coating and drying a copper current collector with a loading amount of was prepared.

[0276]

[0277] Evaluation of negative electrode-separator adhesion (dry adhesion)

[0278] The membrane samples obtained in each example or comparative example were cut into a size of 100 mm (length) x 25 mm (width) to prepare each test piece. After each test piece was laminated with the negative electrode, a first electrode assembly was obtained by heating and pressing at 60°C for 20 seconds (dry adhesion measurement). The laminate was fixed to an adhesive strength measuring device (LLOYD Instrument, LF plus), and the membrane portion was peeled at an angle of 180° at a speed of 25 mm / min at 25°C, and the strength at this time was measured.

[0279] Referring to Table 2 above, the separator of Comparative Example 3 did not form an adhesive bond between the separator and the electrode. On the other hand, Example 1 secured an adhesive strength equivalent to that of the separator of Comparative Example while having a lower compression ratio for the same pressurization time. Accordingly, it was confirmed that the separator according to the present invention has excellent adhesive strength and secures a passage through which the electrolyte can be impregnated, which is advantageous in terms of processability.

[0280]

[0281] Check for Li plating after battery assembly

[0282] First, the positive and negative electrodes were manufactured as described above, and the separators of each example and comparative example were interposed between them to prepare a laminate. Thereafter, the laminate was pressed at a strength of 2.5 MPa under a temperature condition of 60°C to manufacture a first electrode assembly. Thereafter, the first electrode assembly was placed in a battery case, and an electrolyte was injected and sealed. This was left for about 5 minutes. Thereafter, this was activated at a charge rate of 0.5C under a condition of about 40°C and a pressure of 1.0 MPa until an SOC of 65 was reached. The electrolyte was a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 7:3, to which 1 M LiPF6 was added. After completing the activation, the battery was continuously charged and discharged 10 times at a charge rate of 1.0C and a discharge rate of 1.0C, and then the battery was disassembled at an SOC of 80 to check the level of precipitation on the surface of the negative electrode.

[0283]

[0284] Measurement of molecular weight

[0285] Molecular weight (weight-average molecular weight / number-average molecular weight) was measured using gel permeation chromatography (GPC). Agilent Technologies PL GPC220 was used, and the measurement conditions were as follows.

[0286] - Column (maker, model no.): 2 x TSKgel SupermultiporeHZ-M + TSKgel SuperHZ-2500

[0287] - Eleunt: THF

[0288] - Temperature: 40℃

[0289] - Flow rate: 1.0 mL / min

[0290] - Injection volume, sample concentration: 30 ㎕, 1~10 mg / mL

[0291] - Standard: Polystyrene

[0292] - Detector: RI

[0293]

[0294] Measurement of glass transition temperature

[0295] The glass transition temperature (Tg) was measured using a DSC (Differential Scanning Calorimetry, TA Instrument). Samples weighing 10 to 15 mg each were obtained, cooled from ambient temperature to -30°C, and then heated to 200°C at 10°C / min. Measurements were then taken after cooling to -30°C and reheating at 10°C / min.

[0296]

[0297] [Explanation of symbols]

[0298] 10 Porous substrates

[0299] 20 layers of weapon coating

[0300] 100 polymer columns

[0301] 200 inorganic particles

[0302] T s Thickness of the membrane

[0303] T p Protrusion height of polymer column

[0304] T i Height of the inorganic particle filling, T c Height of the inorganic coating layer

Claims

1. Includes a porous polymer substrate and an inorganic coating layer covering one surface or both surfaces of the porous polymer substrate. The above-mentioned inorganic coating layer comprises a plurality of adhesive polymer columns of a predetermined volume, wherein the polymer columns are made of a polymer material and do not have pores, At least a portion of the polymer column is exposed to the surface of the inorganic coating layer and another portion is in contact with the surface of the porous substrate, At least one polymer column is spaced apart from the other polymer columns by a predetermined distance, The space between the above polymer columns is filled with inorganic particles, The above polymer column has a storage modulus (G') at room temperature of 100 Pa or more and 3,500 Pa or less, The above polymer column has a solubility in THF of 15% to 70%, The above solubility is according to the following [Formula 1]: A separator for an electrochemical device; [Formula 1] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100.

2. In paragraph 1, The above membrane has a first compression ratio of 20 to 25% by first compression under pressurized conditions of 2.0 MPa to 4.0 MPa and 55°C to 65°C. The above first compression ratio is a value calculated by [Formula 2] below and refers to the compression ratio (dry compression ratio) before the separator comes into contact with the electrolyte. The height of the inorganic coating layer after compression under the above conditions (T c ) is 1.1 x T i < T < 1.5 x T i And, a separator for an electrochemical device, wherein the protrusion height of the polymer column after compression is 1㎛ or more: [Formula 2] 1st Compression Ratio (%) = {(Initial thickness before 1st compression - Thickness after 1st compression) / (Initial thickness before 1st compression)} x 100.

3. In paragraph 2, The above membrane has a second compression ratio of 30% or more by second compression under pressurized conditions of 0.5 MPa to 1.5 MPa and 35°C to 85°C. The above second compression ratio is calculated by [Formula 3] below, and the above second compression ratio is the compression ratio (wet compression ratio) when the separator is immersed in the electrolyte for more than 5 minutes after the first compression and the electrolyte on the surface is removed and pressurized under the above conditions. The thickness (T) of the weapon coating layer after the second compression is 1.0 x T i < T c ≤ 1.1 x T i And, A separation membrane in which the protrusion thickness of the polymer column after the second compression is 1㎛ or less: [Formula 3] Second compression ratio (%) = {(initial thickness before first compression - thickness after second compression) / (initial thickness before first compression)} x 100.

4. In paragraph 1, D of the above polymer column 50 D of silver inorganic particles 50 A separator for electrochemical devices that is more than twice as large.

5. In paragraph 1, A separator for an electrochemical device, wherein the inorganic coating layer contains 10 to 50 volume% of polymer columns based on 100 volume% of inorganic particles.

6. In paragraph 1, The thickness of the above inorganic particle portion (T) i ) is a polymer column D 50 A separator for electrochemical devices having a particulate matter content of 85% or less.

7. In paragraph 1, D of the above polymer column 10 Silver D 50 More than 30% of D90 is D 50 A separator for electrochemical devices having a p-value of 200% or less.

8. In paragraph 1, A separator for an electrochemical device, wherein the area occupied by the polymer column is 10% to 50% of the surface area of ​​the inorganic coating layer based on the surface view of the separator (top view).

9. In paragraph 1, An electrochemical device separator, wherein at least one polymer column included in the inorganic coating layer has a cross-sectional area (a) of the polymer column confirmed in a cross-section at the lower 5% from the lowest portion of the inorganic coating layer toward the surface, and a cross-sectional area of ​​the column confirmed in a cross-section at the upper 5% from the highest portion toward the bottom, wherein the area (b) is larger than the area (a).

10. In paragraph 1, A separator for an electrochemical device, wherein at least one polymer column included in the inorganic coating layer has a diameter (a) of a lower portion of the polymer column that is shorter than a diameter (b) of an upper portion of the column in a cross-section of the polymer column confirmed in a vertical cross-section of the inorganic coating layer, and a ratio of the diameter (b) to the diameter (a) is 2 to 20.

11. In paragraph 1, A separator for an electrochemical device, wherein the above-mentioned inorganic coating layer has a pore structure due to the interstitial volume between inorganic particles.

12. An electrochemical device comprising a separator for an electrochemical device according to paragraph 1.

13. A step of preparing a laminate comprising at least one anode, at least one separator, and at least one cathode, wherein the separator is interposed between the anode and the cathode and is laminated at least once; A step of manufacturing a first electrode assembly by pressing the above laminate at a strength of 3.0 MPa to 4.0 MPa under temperature conditions of 55°C to 65°C; A step of impregnating the first electrode assembly with an electrolyte; and A method for manufacturing a battery, comprising: a step of applying a pressure of 0.5 MPa to 1.5 MPa to the impregnated first electrode assembly; wherein the separator is according to claim 1.

14. In paragraph 13, A battery manufacturing method wherein pressure is applied to the impregnated first electrode assembly so that the separator and the positive electrode and / or the separator and the negative electrode are in close contact, and the pressure is applied at a temperature of 35°C to 45°C.

15. In paragraph 13, A method for manufacturing a battery, wherein the step of impregnating the first electrode assembly with an electrolyte comprises housing the first electrode assembly in a battery case, and further comprising an aging step before applying pressure after the impregnation.

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