Separator for electrochemical device, and method for manufacturing same

Abstract

The present invention provides a separator for an electrochemical device, comprising a porous polymer substrate and an inorganic coating layer that covers one or both surfaces of the porous polymer substrate, wherein the inorganic coating layer comprises a polymer column part including a predetermined volume of a plurality of adhesive polymer columns, and an inorganic particle part including inorganic particles filled between the polymer columns, the polymer columns are made of a polymer material and have no pores, at least some of the polymer columns are exposed on the surface of the inorganic coating layer and the others are in contact with the surface of the porous polymer substrate, each of the one or more polymer columns is spaced a predetermined interval apart from the other polymer columns, some of the polymer columns in the polymer column part protrude from the surface of the inorganic particle part, and the heights (Tp) of the protruding polymer columns are 1 μm or greater from the surface of the inorganic particle part.

Description

Separator for electrochemical devices and method for manufacturing the same

[0001] The present invention relates to a separator for electrochemical devices such as lithium ion secondary batteries.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0043445, filed March 29, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] 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.

[0005] 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.

[0006] 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 binder resin content is high, the interstitial volume is blocked by the binder resin, making it difficult to secure sufficient porosity. On the other hand, if the binder resin content is insufficient, the electrode and the separator may not be closely adhered, resulting in separation between the electrode and the separator during the battery manufacturing process or battery operation.

[0007] 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.

[0008] 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.

[0009]

[0010] 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.

[0011]

[0012] A 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, wherein the inorganic coating layer comprises a polymer column portion including a plurality of adhesive polymer columns of a predetermined volume and an inorganic particle portion including inorganic particles filled between the polymer columns, wherein the polymer columns are made of a polymer material and do not have pores, at least a portion of the polymer columns is exposed to the surface of the inorganic coating layer, and another portion is in contact with the surface of the porous polymer substrate, and at least one polymer column is spaced apart from another polymer column by a predetermined distance, and some of the polymer columns of the polymer column portion protrude from the surface of the inorganic particle portion, and the height (T) of the protruding polymer columns p ) is provided to be 1 ㎛ or more from the surface of the inorganic particle portion.

[0013] The present invention, in the aforementioned aspect, is a polymer column D 10 D of the above polymer column 50 30% or more of the D of the polymer column 90 D of the above polymer column 50 It may be less than 200% of .

[0014] The present invention, in the aforementioned aspect, is a polymer column D 50 D of silver inorganic particles 50 It may be more than twice the contrast.

[0015] In the above-described aspect, the present invention is characterized in that in any one of the first to third embodiments, the D of the inorganic particles 50 is 0.1 ㎛ to 1.5 ㎛, and D of the polymer column 50 may be 2.0 ㎛ to 7.0 ㎛.

[0016] The present invention, in the aforementioned aspect, has a thickness (T) of the inorganic particle portion i ) is the thickness of the polymer column (T c ) may be less than 85%.

[0017] The present invention, in the aforementioned aspect, has a thickness (T) of the inorganic particle portion i ) is 1.0 ㎛ to 5.0 ㎛, and the thickness of the polymer column (T c ) may be 2.0 ㎛ to 7.0 ㎛.

[0018] The present invention, in the aforementioned aspect, has a thickness (T) of the inorganic particle portion i ) and the thickness (Tc) of the polymer column portion may satisfy the following equation 1.

[0019] 0.2 < < 0.7 … Equation 1

[0020] In the aspect described above, in any one of the first to seventh embodiments of the present invention, the volume of the protruding polymer column may be 25 to 55 volume% with respect to 100 volume% of the inorganic coating layer.

[0021] In the aspect described above, the present invention may be such that when the separation membrane is pressurized under temperature conditions of 25°C to 90°C and pressure conditions of 0.5 MPa to 20 MPa, the inorganic particle portion and the polymer column may have a thickness difference of less than 1 μm.

[0022] In the above-described aspect, the present invention may be such that the surface area of ​​the polymer column exposed to the surface of the inorganic coating layer may be 5% to 80% of the surface area of ​​the inorganic coating layer based on a planar image (top view) of the separation membrane.

[0023] In the aspect described above, the present invention may have a pore structure due to interstitial volume between inorganic particles.

[0024] In the aforementioned aspect 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 a polymer column confirmed in a cross-section at the lower 5% from the lowest portion of the inorganic coating layer toward the surface, and an area (b) of a cross-section of a column confirmed in a cross-section at the upper 5% from the top portion toward the bottom, wherein the area (a) is greater than the area (a).

[0025] In the above-described aspect of the present invention, at least one polymer column included in the inorganic coating layer may have a diameter (a) of a lower portion of the polymer column 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) may be 2 to 20.

[0026] Meanwhile, the present invention relates to an electrochemical device, and includes a separator for an electrochemical device according to any one of the aforementioned aspects.

[0027] 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.

[0028]

[0029] 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.

[0030]

[0031] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the contents of the invention described above, and therefore the present invention should not be interpreted as being limited to matters described in such drawings.

[0032] Figure 1 is a SEM image showing the surface of the inorganic coating layer before flattening of the separator manufactured in Example 1 at a magnification of 500 times.

[0033] Figure 2 shows a SEM image at 2000 times magnification of the surface of the inorganic coating layer before flattening of the separator manufactured in Example 1.

[0034] Figure 3 shows a SEM image at 5000 times magnification of the surface of the inorganic coating layer before flattening of the separator manufactured in Example 1.

[0035] Figure 4 shows a SEM image at 500 times magnification of the surface of the inorganic coating layer after flattening of the separator manufactured in Example 1.

[0036] Figure 5 is a SEM image showing the surface of the inorganic coating layer after flattening of the separator manufactured in Example 1 at a magnification of 5500 times.

[0037] Figure 6 is a SEM image showing the cross-section of the membrane manufactured in Example 1 before flattening, enlarged 5500 times.

[0038] Figure 7 is a SEM image showing the cross-section of the membrane manufactured in Example 1 after flattening, enlarged 5500 times.

[0039] Figure 8 is a schematic diagram showing a cross-section of a separation membrane according to one embodiment of the present invention.

[0040]

[0041] 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.

[0042] 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.

[0043] The terms "about," "substantially," etc., used throughout this specification are used in the sense of, or close to, the numerical values ​​when manufacturing and material tolerances inherent to the meanings stated, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that state exact or absolute values ​​to aid understanding of this specification.

[0044] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0045] D of the polymer column in the present specification 50 refers to the diameter at the 50% point of the cumulative distribution of the number of polymer columns according to their diameter. That is, D of the polymer column 50 refers to the diameter at the 50% point of the cumulative distribution of the number of polymer columns according to their diameter. In addition, D of the polymer column 10refers to the diameter at the 10% point of the cumulative distribution of the number of polymer columns according to the diameter of the polymer column, and D of the polymer column 90 It means the diameter at the 90% point of the cumulative distribution of the number of polymer columns according to the diameter of the polymer column. The diameter 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 diameter distribution is calculated by measuring the difference in the diffraction pattern according to the size of the polymer columns when the polymer columns pass through the laser beam. By calculating the diameter of the polymer column at the points where it becomes 10%, 50% and 90% of the cumulative distribution of the number of polymer columns according to the diameter of the polymer column in the measuring device, respectively, D 10 , D 50 and D 90 can be measured.

[0046] 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.

[0047] In the present invention, the glass transition temperature (Tg) can be measured through a DSC curve derived from a temperature increase analysis of 10 ℃ by differential scanning calorimetry (DSC).

[0048]

[0049] 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.

[0050] The separator for an electrochemical device of the present invention comprises a porous polymer substrate and an inorganic coating layer covering one surface or both surfaces of the porous polymer substrate.

[0051]

[0052] <Separator>

[0053] The present invention provides a separation membrane.

[0054] Fig. 8 is a schematic diagram illustrating a cross-section of a separator of the present invention, particularly showing the state of the separator before compression, in which the polymer columns protrude beyond the inorganic particle portion. The compression may refer to an artificial application of external force during the battery assembly process.

[0055] In one embodiment of the present invention, the separation membrane includes a porous polymer substrate (10) and an inorganic coating layer (20) formed on at least one side or both sides of the porous polymer substrate. The inorganic coating layer (20) includes a polymer column portion including a plurality of adhesive polymer columns (100) having a predetermined volume, and an inorganic particle portion including inorganic particles (200) filled between the polymer columns.

[0056] The thickness of the above membrane (T s) may be 5.0㎛ to 30㎛ and may be appropriately controlled within the above range. For example, it may be 25.0㎛ or less, 20.0㎛ or less, 12.0㎛ or less, or 10.0㎛ or less. In addition, the separation membrane may have a porosity of about 30 vol% to 80 vol%. The porosity may be appropriately controlled within the above 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 / 100cc or more and about 250 sec / 100cc or less. The above air permeability can be appropriately adjusted within the aforementioned range. For example, the air permeability can be 60 sec / 100cc or more, or 70 sec / 100cc or more, or 100 sec / 100cc or more, or 120 sec / 100cc or more, or 150 sec / 100cc or more. Alternatively, the porosity can be 220 sec / 100cc or less, or 200 sec / 100cc or less, or 180 sec / 100cc or less.

[0057] In one embodiment of the present invention, the thickness (T) of the separation membrane s ) can be obtained by cutting a cross-section of a membrane specimen, observing it through SEM, and then taking the thickness of the thickest point as the thickness of the membrane. Alternatively, the thickness of multiple points, two or more, can be measured and their average value can be taken as the thickness of the membrane. If the thickness of four or more points is measured, the lowest and / or highest values ​​can be excluded and the average of the remaining values ​​can be taken. When measuring the thickness of the membrane by the average, it is appropriate to measure it based on the polymer column in addition to the inorganic particle portion.

[0058]

[0059] 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 [Equation 2] below.

[0060] [Formula 2]

[0061] Porosity (vol%) = {1-(apparent density / true density)} Х100

[0062]

[0063] Meanwhile, the apparent density in the above equation can be calculated from [Equation 3] below.

[0064] [Formula 3]

[0065] Apparent density (g / cm) 3 ) = {Weight of the measurement object [g] / (Thickness of the measurement object [cm] Х Area of ​​the measurement object [cm 2 ])}

[0066]

[0067] 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.

[0068] 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 a porous polymer 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=(P1X20) / T1.

[0069]

[0070] In one embodiment of the present invention, the separation membrane may have a compressibility of the thickness of the separation membrane of 25% or more and 40% or less under a pressurized condition, a pressure condition of 0.5 MPa to 20 MPa, or a pressure condition of 2.0 MPa to 8.0 MPa, and a temperature condition of 25°C to 90°C or 55°C to 65°C. The compressibility can be calculated by the following equation 4).

[0071] [Formula 4]

[0072] Compression ratio (%) = {(Initial thickness of the membrane before compression - Thickness of the membrane after compression) / (Initial thickness of the membrane before compression)} x 100.

[0073]

[0074] In addition, in one embodiment of the present invention, the separator may be pressed and flattened under a pressurized condition, a pressure condition of 0.5 MPa to 20 MPa, a pressure condition of 2.0 MPa to 8.0 MPa, or a temperature condition of 25°C to 90°C or a temperature condition of 55°C to 65°C, so that the thickness of the inorganic coating layer may be uniform. Meanwhile, the pressurizing may be hot pressing. This property is advantageous in strengthening the adhesion between the electrode and the separator during the manufacture of the electrode assembly and preventing the occurrence of a gap between the electrode and the separator. That is, under the conditions for lamination of the electrode and the separator, that is, under hot press conditions, the polymer column may exhibit softening properties.

[0075] At this time, the difference in thickness of the separation membrane before and after compression may be 4 μm or more. Meanwhile, the thickness of the separation membrane after compression may be 15 μm or less, or 5 μm to 15 μm.

[0076]

[0077] <Porous polymer substrate>

[0078] The above porous polymer substrate refers to a substrate having multiple pores formed therein as a porous ion-conducting barrier that allows ions to pass through while blocking electrical contact between the cathode and the anode. The pores are structured to be interconnected, allowing gas or liquid to pass from one side of the substrate to the other.

[0079] The material constituting this porous polymer 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 substrate material. Here, the shutdown function refers to the function of preventing thermal runaway of the battery by blocking the movement of ions by melting the thermoplastic resin and closing the pores of the porous substrate when the battery temperature rises. Suitable thermoplastic resins include those with a melting point below 200°C, and polyolefins are particularly preferred.

[0080] 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 polymer substrate may be, but is not particularly limited to, a nonwoven fabric, a porous polymer film, or a laminate of two or more thereof.

[0081] Specifically, the porous polymer substrate is one of the following a) to e).

[0082] a) A porous film formed by melting / extruding a polymer resin,

[0083] b) A multilayer film in which two or more layers of the porous film of a) above are laminated,

[0084] c) A nonwoven web manufactured by accumulating filaments obtained by melting / spinning a polymer resin.

[0085] d) A multilayer film in which two or more layers of the nonwoven web of the above b) are laminated,

[0086] e) A porous composite membrane having a multilayer structure comprising two or more of the above a) to d).

[0087]

[0088] In the present invention, the porous polymer 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.

[0089] In one embodiment of the present invention, the weight average molecular weight (molecular weight (Mw)) of the polyolefin may be 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 the lower limit, it may be difficult to secure sufficient mechanical properties. In addition, if it is greater than the upper limit, the shutdown characteristics may deteriorate or molding may become difficult. In addition, the puncture strength of the porous polymer 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 radius of 0.5 mm and a puncture speed of 2 mm / sec. Meanwhile, the weight average molecular weight can be measured by gel chromatography, etc.

[0090] 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.

[0091] In addition, the porous polymer substrate may have a porosity of 20 vol% to 80 vol% or 30 vol% to 60 vol%, and the average pore size of the porous polymer substrate may be 10 nm to 200 nm, but is not particularly limited thereto.

[0092]

[0093] <Weapon coating layer>

[0094] In the present invention, the separation membrane includes an inorganic coating layer formed on one surface of the porous polymer substrate. The inorganic coating layer includes a polymer column portion including a plurality of adhesive polymer columns of a predetermined volume and an inorganic particle portion including inorganic particles filled between the polymer columns.

[0095] 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%, preferably 70 wt% to 90 wt%, relative to 100 wt% of the inorganic coating layer.

[0096] In addition, the polymer column may be included in an amount ranging from 5 to 30 parts by weight, preferably from 10 to 25 parts by weight, relative to 100 parts by weight of the inorganic particles. If the content of the polymer column is low, it is difficult to secure the adhesive strength at the desired level, but if it is included in an amount exceeding the above range and is too large, the Gurley value and / or porosity of the separation membrane may be lowered, which is not preferable.

[0097] Meanwhile, in the planar image of the inorganic coating layer, the total area of ​​the polymer columns before or after compression or both may be 5% to 80%, 5% to 60%, or 5% to 40% of the total area of ​​the inorganic coating layer. Preferably, it may be 10% to 35%.

[0098] 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 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 together 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.

[0099] 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. When the porosity satisfies the above-described range, it is advantageous in terms of lithium ion permeability, and the surface opening ratio is not too high, so it is suitable for securing adhesion between the separator and the electrode.

[0100]

[0101] Polymer column

[0102] The above-mentioned inorganic coating layer may include a polymer column portion including a plurality of adhesive polymer columns of a predetermined volume, and the polymer columns may include a polymer resin in an amount of 90 wt% or more, 95 wt% or more, or 99 wt% or more relative to 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 polymer substrate.

[0103] In the present invention, one or more of the polymer columns may not have open cell-type pores in their bodies. 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.

[0104] The polymer column may have at least a portion exposed to the surface of the inorganic coating layer and another portion in contact with the surface of the porous polymer substrate.

[0105] In the above-described inorganic coating layer, the polymer columns may be clustered by 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.

[0106] 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.

[0107]

[0108] In one embodiment of the present invention, D of the polymer column 10 Silver D 50 It can be more than 30% of D 90 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.

[0109] In one embodiment of the present invention, D of the polymer column 50 can be about 2.0 ㎛ to 7.0 ㎛ and can be appropriately controlled within the above range. For example, the above D 50 This may have a range of 3.0 μm to 6.0 μm. D of the polymer column 50 It reflects the state before the membrane is pressurized, preferably before slurry preparation.

[0110]

[0111] 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.

[0112] The above compression conditions typically assume the lamination process conditions for electrodes and separators used in electrode assembly manufacturing. These properties are advantageous in strengthening the adhesion between the electrodes and separators during battery manufacturing and ensuring close contact between the electrodes and separators, preventing gaps.

[0113] That is, when the separator according to the present invention is applied to battery manufacturing, the thickness of the inorganic coating layer (Tc) after lamination of the electrode and the separator is greater than that of the polymer column D after lamination. 50 Smaller is preferable.

[0114] 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.

[0115]

[0116] In the present invention, the polymer column preferably has an elastic modulus of 1,000 to 3,500 Pa at room temperature in terms of flattening by pressure. The elastic modulus may more preferably be 1,000 to 3,000 Pa. Preferably, the elastic modulus may be for the material forming the polymer column. In addition, the polymer column has a ratio of the modulus at 60°C to the modulus at room temperature (Modulus (60°C / Modulus (room temperature))) of 0.05 or less, taking into account the temperature application situation in the actual battery assembly process. More preferably, it is 0.01 or more and 0.05 or less. 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 an elastic modulus at a high temperature, such as 55°C to 65°C, for example, 60°C, of ​​0.05 Pa to 100 Pa.

[0117] In addition, more preferably, the polymer column may have at least one tan δ peak in the range of 45°C to 80°C when measured by a Dynamic Mechanical Analyzer (ARES-G2, TA Instrument). If the tan δ peak appears at a temperature lower than 45°C, the adhesive properties between the wound membranes are expressed, which is not preferable, and if the temperature exceeds 80°C, the elastic modulus does not drop sharply even when the temperature is applied, making it difficult to flatten the polymer column in high-temperature pressurization.

[0118] In one embodiment of the present invention, the elastic modulus can be measured using a rheological property measuring equipment (Dynamic Mechanical Analyzer (DMA), ARES-G2, TA Instrument). In a specific embodiment, the elastic modulus can be confirmed by performing a temperature sweep test under temperature conditions of -60°C to 80°C and a frequency of 1.0 rad / s. In addition, the storage stress (G', storage modulus) at 45°C and the storage stress (G', storage modulus) slope at 60°C to 70°C can be measured through the DMA.

[0119]

[0120] In one embodiment of the present invention, the polymer column is preferably a material that is non-reactive within a lithium secondary battery and can provide bonding strength between the separator and the electrode. Considering this aspect, in the present invention, the polymer column may comprise an acrylic polymer. For example, the acrylic material 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 replaced with another substituent.

[0121] However, there is a concern that the polymer column may dissolve and lose adhesiveness after liquid electrolyte injection, or that the viscosity of the liquid electrolyte may increase due to the dissolved components, thereby increasing the resistance of the lithium secondary battery. Therefore, it is desirable to have an appropriate solubility as described below. For example, the solubility in organic solvents or electrolytes can be reduced by cross-linking the surface of the material forming the polymer column.

[0122] In a specific embodiment, the polymer column is dissolved in THF (Tetrahydrofuran) for 1 to 48 hours, and the dissolved amount (weight) is 55% or less, preferably 35% or less, more preferably 25% or less, even more preferably 22% or less, and most preferably 20% or less.

[0123]

[0124] In one embodiment of the present invention, one or more polymer columns may have a cross-sectional area (a) of the polymer column ascertained in a cross-section at the lower 5% from the bottom of the inorganic coating layer toward the surface, and a cross-sectional area (b) of the polymer column ascertained 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 when 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 the shape of the polymer column after it is flattened after protrusion.

[0125]

[0126] Together with or independently of this, one or more polymer columns may have a diameter (a) at the bottom of the polymer column that is shorter than a diameter (b) at the top 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 is flattened by pressurization. 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 top 5% point from the top of the polymer column toward the bottom, and the lower diameter refers to the diameter at the bottom 5% point from the bottommost part of the polymer column toward the top.

[0127] In one embodiment of the present invention, the length of the diameter and / or the size of the cross-section of the polymer column can be measured for an area corresponding to a specific gray level corresponding to the polymer column by dividing the SEM image for the horizontal or vertical cross-section of the separation membrane into gray levels. 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 may be a value of 0 to 255. In a specific embodiment of the present invention, the polymer column may have a gray level of 10 to 50, and the inorganic particle may have a gray level of 160 to 220. Accordingly, the area of ​​the polymer column can be set and defined from pixels having gray levels of 10 to 50 in the SEM image of any cross-section of the separation 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) on a cross-section of an electrode obtained by argon ion milling, and then performing image processing.

[0128] 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.

[0129]

[0130] <Inorganic particles>

[0131] 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 those that can operate within the operating voltage range of the applied electrochemical device (e.g., Li / Li). + There is no particular limitation as long as no oxidation and / or reduction reaction occurs at a reference voltage of 0 to 5 V. In particular, when using inorganic particles with a high dielectric constant as inorganic particles, it 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.

[0132] 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), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC and TiO2 or mixtures thereof.

[0133] 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 glasses such as Li3PO4-Li2S-SiS2 (Li x Si y S z , 0 < x < 3, 0 <y < 2, 0 < z < 4), LiI-Li2S-P2S5등과 같은 P2S5계열 글래스(Li x P y S z , 0 < x < 3, 0< y < 3, 0 < z < 7) or mixtures thereof.

[0134] Also, D of inorganic particles 50 There is no special limitation, but in order to form a coating layer of uniform thickness and an appropriate porosity, it is preferably in the range of 0.1 ㎛ to 1.5 ㎛, or 0.4 ㎛ to 1.3 ㎛. If it is less than the lower limit of the above range, the dispersibility may be reduced, and if it exceeds the upper limit of the above range, the thickness of the inorganic coating layer formed may increase. D of the inorganic particles 50 D is described in the definition of this specification 50D of inorganic particles present in the inorganic particle compartment, measured according to the measurement method 50 It can also satisfy the above-described range.

[0135]

[0136] <Polymer column section and inorganic particle section>

[0137] In one embodiment of the present invention, the inorganic coating layer includes a polymer column portion including a plurality of adhesive polymer columns of a predetermined volume and an inorganic particle portion including inorganic particles filled between the polymer columns.

[0138] The inorganic particle portion may further include a binder resin to secure adhesion between the inorganic particles and between the inorganic particles and the porous polymer matrix. The inorganic particle 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 column may be bonded by the adhesive properties of the polymer column or may be bonded via a binder resin.

[0139]

[0140] The thickness of the above polymer column (T c) may be 2.0 ㎛ to 7.0 ㎛, 2.2 to 6.0, 2.5 ㎛ to 5.8 ㎛, or 3.2 ㎛ to 5.3 ㎛. The thickness (Tc) of the polymer column portion may be larger than the diameter of the polymer column itself due to the interaction, such as compression, between the polymer column and the inorganic particles arranged around the polymer column in the separation membrane. When the thickness of the polymer column portion is less than the lower limit, the difference with the thickness of the inorganic particle portion may be small, so that the content of the protruding polymer column may be small, and thus the adhesive strength of the separation membrane may be inferior. On the other hand, when the thickness of the polymer column portion is more than the upper limit, the difference with the thickness of the inorganic particle portion may be large, so that the polymer column may be detached from the inorganic coating layer.

[0141] 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 portion when not artificially pressurized after manufacture. That is, they may protrude from the surface of the inorganic particle portion. In one embodiment of the present invention, when the polymer columns protrude outside the inorganic particle portion, the thickness (T) of the inorganic particle portion i ) is the thickness of the polymer column (T c ) may be 85% or less. Meanwhile, in one embodiment of the present invention, the thickness of the inorganic particle portion may be D of the polymer column. 50 It may be 20% or more. Meanwhile, in one embodiment of the present invention, the height (Tc) of the polymer column may be obtained by cutting a cross-section of a membrane specimen and observing it through SEM, and then taking the value of the highest part of the polymer column.

[0142]

[0143] In a specific embodiment, the thickness (T) of the inorganic particle portion i ) may be 1.0 ㎛ to 5.0 ㎛, 1.5 ㎛ to 4.0 ㎛, preferably 2.0 ㎛ to 2.6 ㎛. The thickness (T) of the inorganic particle portion i) can preferably be 1.0㎛ or more, and within the above numerical range, the adhesion with 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㎛ or less, it is advantageous in terms of cycle characteristics and resistance characteristics of the battery. In addition, since the thickness of the separator is reduced, the energy density of the battery can be improved when applied to the battery. When the inorganic coating layer is disposed on both sides of the porous polymer substrate, the thickness of the inorganic particle portion refers to a value measured for the inorganic coating layer disposed on either side.

[0144] In one embodiment of the present invention, the thickness (T) of the inorganic particle portion i ) and the thickness (Tc) of the polymer column portion may satisfy the following equation 1.

[0145] 0.2 < < 0.7 … Equation 1

[0146] The above equation 1 is, T c T for c and T i It may mean the ratio of the thickness difference of the inorganic particle portion. If the ratio is less than the lower limit, the difference in thickness of the inorganic particle portion may be small, so that the content of the protruding polymer column may be small, and thus the adhesive strength or heat resistance of the separator may be inferior. On the other hand, if the ratio is more than the upper limit, the difference in thickness of the inorganic particle portion may be large, so that the polymer column may be detached from the inorganic coating layer, or the uniformity of the polymer column may be poor, and the thickness uniformity of the manufactured electrode assembly may be inferior.

[0147]

[0148] In one embodiment of the present invention, the one or more polymer columns may protrude a predetermined height outside the surface of the inorganic coating layer. Here, the protrusion of the polymer columns outside the surface of the inorganic coating layer means the thickness (T) of the inorganic particle portion of the inorganic coating layer. i ) compared to the thickness of the polymer column (Tc ) is high, the thickness of the inorganic particle part (T i ) means having a higher height.

[0149]

[0150] In one embodiment of the present invention, the height (T) of the protruding polymer column p ) is 1 ㎛ or more from the surface of the inorganic particle portion. In the inorganic coating layer, a plurality of polymer columns are embedded so as to be exposed or protrude outside the inorganic particle portion, and the protruding height (T) of some of the polymer columns p ) is 1 ㎛ or more. For example, the height (T) of the protruding polymer column p ) may be greater than 1 ㎛ and less than 6 ㎛, for example, less than 5 ㎛, less than 4.9 ㎛, less than 4 ㎛, less than 3 ㎛, less than 2.6 ㎛, less than 2.5 ㎛, less than 2.2 ㎛, or less than 2.1 ㎛, and may be greater than 1 ㎛, more than 1.5 ㎛, or more than 2 ㎛. In addition, some of the polymer columns exposed to or protruding from the surface of the inorganic particle portion may be in contact with the porous substrate. Here, the fact that the polymer columns protrude outside the surface of the inorganic particle portion means that the height of the polymer columns is higher than the height of the inorganic particle portion.

[0151]

[0152] The height (T) of the above protruding polymer column p ) is less than the lower limit, the content of the protruding polymer columns may decrease, and thus the adhesive strength of the membrane may be inferior. On the other hand, if the height (Tp) of the protruding polymer columns exceeds the upper limit, the polymer columns may detach from the inorganic coating layer. In this case, the height of the protruding polymer columns may specifically mean the height before the membrane is pressurized.

[0153] In one embodiment of the present invention, the volume of the protruding polymer column may be 25 vol% to 55 vol% or 30 vol% to 50 vol% with respect to 100 vol% of the inorganic coating layer. If the volume of the protruding polymer column is less than the lower limit, the adhesion of the separator may be insufficient, and if it exceeds the upper limit, the difference in thickness between the inorganic particle portion and the polymer column may be large, so that the polymer column may be detached from the inorganic coating layer, or the uniformity of the polymer column may be reduced, and the thickness uniformity of the manufactured electrode assembly may be inferior. The volume of the protruding polymer column may be measured by an atomic force microscope (AFM), which will be described later. The volume of the protruding polymer column may be calculated by measuring the protrusion height, the radius and diameter of the protrusion, etc. with the AFM.

[0154]

[0155] In one embodiment of the present invention, the thickness (T) of the inorganic particle 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. For example, the average value of 2 to 10 points can be taken for an area of ​​50 ㎛ or less on each side. Alternatively, in the case of a cross-section, the average value of 2 to 10 points can be taken for a length of 50 ㎛ or less. If the thickness of four or more points is measured, the average value of the remaining values ​​can be taken, excluding the lowest and / or highest values.

[0156] In addition, in one embodiment of the present invention, the thickness (T) of the polymer column portion c ) can be obtained by cutting a cross-section of a membrane specimen and observing it through SEM, and then taking the value of the highest part of the polymer column.

[0157] In addition, in one embodiment of the present invention, the protrusion height (Tp) of the polymer column can be obtained by cutting a cross-section of a membrane specimen and observing it through SEM, and then taking the value of the part where the gap between the inorganic particle filling portion and the polymer column is the largest.

[0158] Alternatively, in one embodiment of the present invention, the height of the protruding polymer columns can be measured by atomic force microscopy (AFM). For example, the height of the protruding polymer columns can be obtained by scanning the cross-sectional sample surface using an AFM (Atomic Force Microscopy) device to obtain an image converted to a 2D scale. Through the measurement, a map in which the height and the depth of the electrical resistance value are expressed as color shades is obtained, and the distribution of the surface resistance can be visually confirmed by the difference in color shades. Specifically, using an AFM device, a height image of a predetermined size, for example, 40 μm x 40 μm, is obtained. Thereafter, the inorganic coating layer is masked using Gwyddion S / w, etc., and the average height value is confirmed. Thereafter, the protruding polymer columns are masked, and the maximum height of each polymer column is confirmed. Thereafter, the difference between the height of the protruding polymer columns and the average height of the inorganic coating layer is measured.

[0159] To this end, first, a sample to be measured in an AFM (Atomic Force Microscopy) device is prepared. The cross-sectional sample manufactured through the above process is attached to an AFM metal disk with the cross-section facing upward, and silver paste or the like is applied so that a conductive path can be formed between the portion other than the milled cross-section and the AFM metal disk. The prepared AFM measurement sample is loaded into the device, and after laser alignment, the cross-section is selected as the measurement portion using an optical microscope. Thereafter, the electrode cross-section is contacted with an AFM probe, and the current flowing through the sample between the AFM probe and the contact electrode is measured, and the diffusion resistance is obtained from the measured current.

[0160] According to one embodiment of the present invention, the operating conditions of the scanning diffusion resistance microscope for analyzing the electrode cross-section sample are, for example, as follows. The AFM equipment is not particularly limited as long as it can visually image the resistance distribution according to the scanning diffusion resistance microscope method. For example, the NX10 (Park Systems Co.) can be used.

[0161]

[0162] In one embodiment of the present invention, the separator may be pressed and flattened under a pressurized condition, a pressure condition of 0.5 MPa to 20 MPa or a pressure condition of 2.0 MPa to 8.0 MPa and a temperature condition of 25°C to 90°C or a temperature condition of 55°C to 65°C, so that the thickness of the inorganic coating layer may be uniform. Meanwhile, the pressurization may be hot pressing. This property is advantageous in strengthening the adhesion between the electrode and the separator during the manufacture of the electrode assembly and in preventing the occurrence of a gap between the electrode and the separator. That is, under the conditions for lamination of the electrode and the separator, i.e., under hot press conditions, the polymer column may exhibit softening properties.

[0163]

[0164] In one embodiment of the present invention, the separation membrane has a thickness (T) of the polymer column portion after compression under pressurized conditions of 0.5 MPa to 20 MPa and 25°C to 90°C. c ) is the thickness of the inorganic particle part (T i ) or the thickness of the inorganic particle portion (T i ) is larger than the thickness of the inorganic particle part (T i ) may be 1.1 times or less, or less than 1.1 times. In addition, the height of the polymer column protruding from the inorganic coating layer after compression may be less than 1 ㎛, 0.8 ㎛ or less, 0.6 ㎛ or less, 0.5 ㎛ or less, 0.3 ㎛ or less, or 0.2 ㎛ or less. That is, the height difference between the inorganic particle portion and the polymer column portion is reduced, so that the separation membrane is flattened. Referring to FIG. 8, in the present invention, 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 polymer substrate. In the present invention, the T c may be equal to 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.

[0165] The above compressibility may be primarily due to deformation (compression) of the polymer column as described below.

[0166]

[0167] 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.

[0168]

[0169] The above compression conditions typically assume the lamination process conditions for electrodes and separators used in electrode assembly manufacturing. These properties are advantageous in strengthening the adhesion between the electrodes and separators during battery manufacturing and ensuring close contact between the electrodes and separators, preventing gaps.

[0170] Meanwhile, in the present specification, the flattening may be such that the thickness of the inorganic particle portion and the height of the polymer column portion are the same or the deviation between the inorganic particle portion and the polymer column portion is less than 1 ㎛, 0.8 ㎛ or less, 0.6 ㎛ or less, 0.5 ㎛ or less, 0.3 ㎛ or less, or 0.2 ㎛ or less under the above-mentioned pressing conditions. In one embodiment of the present invention, the height of the polymer column may be the highest height (T) among the polymer columns. c ) can be used as a standard.

[0171] That is, when the separator according to the present invention is applied to battery manufacturing, an inorganic coating layer (T) is formed after laminating the electrode and the separator. c ) thickness of polymer column D 50 Smaller is preferable.

[0172] 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.

[0173]

[0174] In one embodiment of the present invention, the surface of the separator is measured from a top view using SEM, and the surface area of ​​the polymer columns exposed to the surface of the inorganic coating layer may be 5% or more, 8% or more, or 10% or more, and 80% or less, 70% or less, 60% or less, or 50% or less, based on a planar image (top view) of the separator, of 100% of the surface area of ​​the inorganic coating layer. In this case, the separator may be measured after being pressurized under conditions of a pressure of 0.5 MPa to 20 MPa, 1 MPa to 10 MPa, or 2 MPa to 8 MPa and a temperature of 25°C to 90°C or 55°C to 65°C, or may be measured before being pressurized. When the surface area of ​​the polymer columns exposed to the surface of the inorganic coating layer satisfies the above-described range, the adhesion of the separator, the Gurley value, and / or the porosity of the separator may be excellent.

[0175]

[0176] Binder resin

[0177] Additionally, as described above, the inorganic coating layer may further include a binder resin to enhance the bonding strength. In the inorganic coating layer, the inorganic particles and the binder resin may be included in a weight ratio of 70:30 to 99.9:0.1 or 70:30 to 99:1.

[0178]

[0179] 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.

[0180] 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.

[0181]

[0182] 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.

[0183]

[0184] <Method for manufacturing a separation membrane>

[0185] 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.

[0186] 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 onto a porous polymer substrate and dried.

[0187] 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.

[0188] Thereafter, the obtained separator can be dried to form an inorganic coating layer integrally on the porous polymer substrate. At this time, the drying temperature of the separator is preferably set to a temperature of +20°C or lower than the temperature at which the tan δ peak of the polymer column material is observed, in order to prevent deformation of the polymer column.

[0189] 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.

[0190] The above slurry can be applied using conventional coating methods such as a Meyer bar, die coater, reverse roll coater, or gravure coater. When the above inorganic coating layer is to be formed on both sides of a porous substrate, the coating solution can be applied to each side and then dried, or the coating solution can be applied to both sides of the porous substrate simultaneously and then dried.

[0191] In addition, the separation membrane of the present invention can also be manufactured by a method in which the inorganic coating layer and the porous polymer substrate are manufactured separately, these sheets are overlapped and combined, and then composited by thermal compression or an adhesive. As a method for obtaining the inorganic coating layer as an independent sheet, a method in which the slurry is applied onto a peeling sheet, an inorganic coating layer is formed by the above-described method, and only the inorganic coating layer is peeled off, etc.

[0192] 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.

[0193]

[0194] Lithium secondary battery

[0195] Meanwhile, the present invention provides a secondary battery including the separator. The secondary 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 low-resistance separator having the characteristics described above.

[0196]

[0197] 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 xA 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.

[0198]

[0199] 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.

[0200]

[0201] 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.

[0202]

[0203] 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.

[0204]

[0205] 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.

[0206]

[0207] The electrode assembly prepared as above can be placed in an appropriate case and an electrolyte can be injected to manufacture a battery.

[0208]

[0209] In the present invention, the electrolyte is A + B - As a salt with the same structure, 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.

[0210]

[0211] 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.

[0212] In a specific embodiment of the present invention, the ester compound may include at least one selected from the group consisting of isobutylpropionate, isoamylpropionate, isobutylbutyrate, isopropylpropionate, methylpropionate, ethylpropionate, propylpropionate, butylpropionate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methylbutyrate, ethylbutyrate, propylbutyrate, and butylbutyrate.

[0213]

[0214] 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.

[0215]

[0216] 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.

[0217]

[0218] <Example 1>

[0219] Inorganic particles (Al2O3, D 50 Polyvinyl alcohol (Apac, SBC-1810) as a binder resin and carboxyl methyl cellulose (Daicel, Daicel1220) as a dispersant resin were added to water as a solvent in a ratio of 96:2:2 and a dispersion process using a bead mill was performed to obtain a mixture. Polymer particles for a polymer column (D) were added to the mixture. 50 4.1 ㎛) 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 11 parts by weight based on 100 parts by weight of inorganic particles. The dispersion slurry was applied to a porous polymer substrate (Toray B09PJ1, thickness 9 ㎛) by a microgravure coating method and dried to obtain a separator. In addition, the opposite side was coated and dried in the same manner to obtain a double-coated separator. The loading amount (one side) of the inorganic coating layer in the separator was 5.2 g / m 2 It was.

[0220] Figures 1 to 3 show SEM images (5.0 kV) of the surface of the inorganic coating layer of the manufactured separator at magnifications of 500, 2000, and 5000 times. In addition, Figure 6 shows an SEM image of the cross-section of the inorganic coating layer of the manufactured separator at magnifications of 5500 times. Referring to these, it was confirmed that the polymer columns were exposed to the surface of the inorganic particle portion, and that the lower ends thereof were in contact with the porous polymer substrate. In addition, it was confirmed that each polymer column was spaced apart from each other by a predetermined interval and distributed in an island-like manner.

[0221] Meanwhile, the obtained separator was pressed with a hot press at 2.5 MPa and 65°C for 20 seconds to flatten the surface. Figures 4 and 5 show SEM images of the surface of the inorganic coating layer after flattening, magnified 500x and 5500x, respectively. Figure 7 shows an SEM image of the cross-section of the separator manufactured in Example 1 after flattening, magnified 5500x. Referring to this, it was confirmed that the protruding portion of the polymer column was pressed and flattened.

[0222]

[0223] <Examples 2 to 5>

[0224] Examples 2 to 5 were manufactured in the same manner as in Example 1, except that the content of polymer particles for the polymer column or the amount of the inorganic coating layer applied was changed as shown in Table 2.

[0225]

[0226] <Comparative Example 1>

[0227] Comparative Example 1 was manufactured in the same manner as Example 1, except that polymer particles for the polymer column were not used.

[0228]

[0229] Comparative Example 2

[0230] Comparative Example 2 was manufactured in the same manner as Example 1, except that the thickness of the inorganic particle portion was adjusted to have the height of the protruding polymer column as shown in Table 2.

[0231]

[0232] [Experimental Example]

[0233] <Experimental Example 1: Measurement of solubility, elastic modulus, D50, and Tg of polymer particles for polymer columns>

[0234] Solubility

[0235] In the comparative examples and examples, polymer materials used as polymer columns were dried at 60°C to produce 0.3 g samples. The samples were placed in an 80-mesh mesh sieve and dissolved in THF (Tetrahydrofuran) for 24 hours. The residual weight was compared to the initial weight. The solubility was calculated based on [Equation 5] below. This is summarized and presented in [Table 1] below.

[0236] [Formula 5]

[0237] Solubility (%) = {(Weight measured before immersion - Weight measured after immersion) / (Weight measured before immersion)} x 100

[0238] Elasticity modulus

[0239] A 40 cm x 60 cm 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 of the sample was measured. The elastic modulus was measured using a rheological property measuring equipment (Dynamic Mechanical Analyzer (DMA), ARES-G2, TA Instrument). The elastic modulus was confirmed by conducting a temperature sweep test under temperature conditions of -60°C to 80°C and a frequency of 1.0 rad / s.

[0240] Tg measurement

[0241] 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. The samples were then cooled to -30°C and reheated at 10°C / min, and then measured.

[0242] Solubility (%) Elasticity (25℃, Pa) D 50(㎛)Tg(℃)Polymer column 19.01,3814.159.4

[0243] <Experimental Example 2: Membrane Thickness Measurement>

[0244] In the examples and comparative examples, the thickness of the membrane was determined by cutting a cross-section of the membrane specimen and observing it through SEM, and the thickness of the thickest point was taken as the thickness of the membrane. Meanwhile, the thickness of the inorganic particle part (T i ) was the average of the values ​​measured at three random points. This was summarized and presented in [Table 1].

[0245]

[0246] <Experimental Example 3: Measurement of the height and volume ratio of protruding polymer columns>

[0247] The surface of the membranes manufactured in each Example and Comparative Example was measured using an atomic force microscope (NX10, Park systems Co., Ltd.). Specifically, the membranes manufactured in each Example and Comparative Example were attached to a metal disk for AFM using carbon tape, and the experiment was conducted according to the standard operating method (smartscan, SOP-0590-0k) to obtain height image data of 40 ㎛ x 40 ㎛ in size, and image processing and analysis were performed in XEI SW. The height of the protruding polymer columns compared to the inorganic coating layer was analyzed using Gwyddion S / W. The experiment was performed at three points on the membranes of the Example and Comparative Examples, and then the average was taken. Meanwhile, the volume ratio of the protruding polymer columns was derived using the Gwyddion S / W.

[0248]

[0249] <Experimental Example 4: Evaluation of Dry Adhesion of Electrode-Separator>

[0250] Manufacturing of anodes and cathodes

[0251] LiNi as a cathode active material 0.8 Co 0.1 Mn 0.1O2, 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 85:5:10 to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated on a sheet-shaped aluminum current collector and dried to obtain a final positive electrode loading of 3.3 mAh / cm. 2 The polarity was prepared to make this happen.

[0252] Artificial graphite and natural graphite as negative active materials, carbon black as conductive material, and polyvinylidene fluoride (PVdF) as binder were mixed in a weight ratio of 75:5:20, and N-methylpyrrolidone (NMP) as a solvent was added to prepare a negative electrode slurry. The negative electrode slurry had a capacity of 3.8 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.

[0253] The above-mentioned manufactured cathode was laminated between separators, a separator was laminated on the cathode, and an anode was further laminated on the separator.

[0254]

[0255] Evaluation method and results

[0256] The membrane samples obtained in each example and 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 laminate was obtained by heating and pressing at 70°C for 20 seconds. 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.

[0257]

[0258] <Experimental Example 5: Electrode-Separator Wet Adhesion Evaluation Method>

[0259] 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. Each test piece was laminated with the positive electrode manufactured according to the above experimental example, and then heated and pressed at 50°C for 20 seconds to obtain a laminate. This was immersed in an electrolyte and maintained for 24 hours. Afterwards, each laminate was taken out of the electrolyte and 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. The electrolyte was a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 7:3 and contained LiPF6 in a concentration of 1 M.

[0260]

[0261] <Experimental Example 6: Resistance Measurement>

[0262] The resistance of the separators of each example and comparative example was measured by impedance measurement. Coin cells were fabricated by sandwiching each separator between stainless steel plates, and 1 M LiPF6 was injected into an ethylene carbonate / ethyl methyl carbonate (EC / EMC, volume ratio 30:70) electrolyte. The resistance was measured through electrochemical impedance spectroscopy analysis using Solaton's 1470E cell test system and frequency response analyzer 1255B at 25°C with a scan range of 100,000 Hz to 10,000 Hz.

[0263]

[0264] <Experimental Example 7: Measurement of thermal shrinkage>

[0265] The membranes manufactured in each example and comparative example were cut to a size of 50 mm x 50 mm, placed between A4 papers, and placed in a convection oven at 120°C for 1 hour, and then the thermal shrinkage rates in the machine direction (MD) and transverse direction (TD) were measured.

[0266] Example 1 Comparative Example 1 Comparative Example 2 Example 2 Example 3 Example 4 Example 5 Thickness of the separation membrane (T s ) (㎛)7.17.07.17.16.97.07.0Height of the extruded polymer column (T p ) (㎛): AFM1.80.00.91.821.14.9Volume % for 100 vol % of inorganic coating layer of protruding polymer column: AFM300.0456719--Thickness of polymer column part (T c ) (㎛):4.12.24.14.04.25.87.0 Thickness of inorganic particles (T i )(㎛) :2.32.23.22.22.24.72.1 Application amount of inorganic coating layer (g / m) 2 )5.23.36.94.85.03.17.6 Height ratio of protruding polymer columns to inorganic particle portion ((T c - T i ) / T c )0.43-0.220.450.470.190.7Heat shrinkage (good)(bad)(good)(good)(good)(bad)(good)Cathode / Separator Dry Adhesion (gf / 25mm)17.14.66.724.210.48.725.5Separator thickness after pressing (T s ) (㎛)6.86.76.96.86.86.86.8Polymer column protrusion thickness after press (㎛)0.20.00.10.30.50.12.4Anode / Separator Wet adhesion (gf / 15mm)11.83.13.519.64.74.518.5Resistance (ohm)0.790.830.810.800.820.800.83

[0267] Examples 1 to 5 satisfied a height of the protruding polymer column before pressurization of 1 ㎛ or more, and thus, compared to Comparative Examples 1 and 2, not only did they have excellent adhesion to the electrode, but they also secured sufficient porosity, confirming excellent resistance and ionic conductivity characteristics. On the other hand, Comparative Example 1 did not use polymer particles for the polymer column, so the thermal shrinkage rate was poor, and the dry adhesion of the negative electrode-separator and the wet adhesion of the positive electrode-separator were reduced.

[0268] Meanwhile, Comparative Example 2 used polymer particles for a polymer column, but the height of the protruding polymer column (T p ) was less than 1 ㎛, which resulted in poor adhesive strength.

Claims

1. It comprises 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 includes a polymer column portion including a plurality of adhesive polymer columns of a predetermined volume and an inorganic particle portion including inorganic particles filled between the polymer columns, The above polymer column is made of a polymer material and does 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 polymer substrate, At least one polymer column is spaced apart from the other polymer columns by a predetermined distance, Some of the polymer columns of the above polymer column portion protrude from the surface of the inorganic particle portion, The height (T) of the above protruding polymer column p ) is a separator for an electrochemical device characterized in that the surface of the inorganic particle portion is 1 ㎛ or more.

2. In claim 1, D of the above polymer column 10 D of the above polymer column 50 30% or more of the D of the polymer column 90 D of the above polymer column 50 A separator for an electrochemical device characterized by having a purity of 200% or less.

3. In claim 1, D of the above polymer column 50 D of silver inorganic particles 50 A separator for electrochemical devices with a contrast ratio of more than twice that of a conventional membrane.

4. In claim 1, D of the above inorganic particles 50 is 0.1 ㎛ to 1.5 ㎛, and D of the polymer column 50 A separator for an electrochemical device, characterized in that the thickness is 2.0 ㎛ to 7.0 ㎛.

5. In claim 1, The thickness of the above inorganic particle portion (T i ) is the thickness of the polymer column (T c ) is 85% or less of the separator for an electrochemical device.

6. In claim 1, The thickness of the above inorganic particle portion (T i ) is 1.0 ㎛ to 5.0 ㎛, and the thickness of the polymer column (T c ) is a separator for an electrochemical device, characterized in that it has a thickness of 2.0 ㎛ to 7.0 ㎛.

7. In claim 1, The thickness of the above inorganic particle portion (T i ) and the thickness (T) of the polymer column portion c ) is a separator for an electrochemical device, characterized in that it satisfies the following equation 1: 0.2 < < 0.7 … Equation 1 8. In claim 1, A separator for an electrochemical device, characterized in that the volume of the protruding polymer column is 25% to 55% by volume with respect to 100% by volume of the inorganic coating layer.

9. In claim 1, A separator for an electrochemical device, characterized in that when the separator is pressurized under temperature conditions of 25°C to 90°C and pressure conditions of 0.5 MPa to 20 MPa, the inorganic particle portion and the polymer column have a thickness difference of less than 1 μm.

10. In claim 1, A separator for an electrochemical device, characterized in that the surface area of ​​the polymer column exposed to the surface of the inorganic coating layer is 5% to 80% of the surface area of ​​the inorganic coating layer based on a planar image (top view) of the separator.

11. In claim 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. In claim 1, A separator for an electrochemical device, wherein at least one polymer column included in the inorganic coating layer has an area (a) of a cross-section of a polymer column confirmed in a cross-section at the lower 5% from the lowest portion of the inorganic coating layer toward the surface, and an area (b) of a cross-section of a column confirmed in a cross-section at the upper 5% from the top toward the bottom, wherein the area (a) is greater than the area (a).

13. In claim 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 the ratio of the diameter (b) to the diameter (a) is 2 to 20.

14. An electrochemical device comprising a separator for an electrochemical device according to claim 1.

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