Separator for electrochemical device and preparation method thereof

Abstract

The present invention relates to a separator prepared by a dry process and an electrochemical device comprising same. A separator according to an aspect of the present invention is prepared by a dry process, and a battery to which the separator is applied exhibits the advantage of implementing high-rate charging characteristics.

Description

Separator for electrochemical devices and method for manufacturing the same

[0001] The present invention relates to a separator, a method for manufacturing the same, and an electrochemical device including the same. Specifically, the present invention relates to a separator manufactured by a dry process.

[0002] This application claims priority based on Korean Patent Application No. 2024-0138710 filed with the Korean Intellectual Property Office on October 11, 2024, and all contents disclosed in the specification of said application are incorporated into this application.

[0003] Lithium-ion 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 recently being applied in various fields, including automobiles.

[0004] Lithium secondary batteries are manufactured through a process in which an electrode assembly, comprising a positive electrode, a separator, and a negative electrode as a single unit, is inserted into a battery case, and then an electrolyte is injected and sealed. Polyolefin-based porous substrates are typically used as separators for lithium secondary batteries.

[0005] Meanwhile, manufacturing methods for porous substrates are broadly classified into wet processes and dry processes. A wet process refers to a process in which a polymer material is mixed with a plasticizer, extruded to form a sheet, and then the plasticizer is removed from the sheet to form pores. In a wet process, the pore size is determined by the type of plasticizer and the compatibility between the plasticizer and the polymer material, so there is an advantage of uniform pore size; however, the process is not easy to operate depending on changes in the polymer material, and there is a problem that the solvent used to extract the plasticizer is harmful to the human body and the environment.

[0006] The dry process is a process in which a precursor polymer film is manufactured through extrusion, fiber orientation is controlled through heat treatment, and pores are formed by tearing the fibers of the polymer film through stretching. Unlike the wet process, the dry process does not use extraction solvents for plasticizer extraction, so it has the advantage of being more environmentally friendly compared to the wet process. Furthermore, due to the characteristics of the materials and the process, separators using porous substrates manufactured by the dry process have a more favorable effect on the discharge output performance of the battery compared to the wet process.

[0007] Meanwhile, to improve the rapid charging performance of electric vehicles, it is important to enhance not only the discharge output of lithium-ion batteries but also their rapid charging performance. Therefore, it is necessary to further improve the charging output of dry-process separators, which already possess excellent discharge output performance.

[0008] Accordingly, there is a need to develop dry separators suitable for use in high-output electrochemical devices.

[0009] Therefore, the problem that the present invention aims to solve is to provide a separator capable of realizing not only high discharge output but also high-rate charging when used in an electrochemical device, and a method for manufacturing the same.

[0010] Specifically, the present invention aims to provide a separator substrate for increasing the charge capacity of an electrochemical device, for example, a lithium secondary battery, a method for manufacturing the same, a separator using the same, and an electrochemical device including the same.

[0011] In order to solve the above problem,

[0012] According to one aspect of the present invention, a separation membrane of the following embodiments is provided.

[0013] The separator according to the first embodiment is,

[0014] It comprises a porous polymer matrix including a polyolefin resin, and

[0015] The above porous polymer matrix is,

[0016] The main chain of the above polyolefin resin and,

[0017] Micro fibrils extending in one direction not parallel to the direction in which the above-mentioned main chain extends, and

[0018] It includes pores formed between the above microfibrils,

[0019] The above pores include micropores having a diameter of 20 nm or more and less than 40 nm, and mesopores having a diameter of 40 nm or more and less than 60 nm, and

[0020] The total volume of the above small pores is made larger than the total volume of the above medium pores.

[0021] According to the second embodiment, in the first embodiment,

[0022] The above polyolefin-based resin includes polypropylene resin, and

[0023] The weight of the polypropylene resin may be 95% or more based on the total weight of the porous polymer matrix.

[0024] According to the third embodiment, in the first embodiment or the second embodiment,

[0025] The cross-section of the above pore may include an elliptical shape with an aspect ratio greater than 1 according to Formula 1 below.

[0026] [Equation 1]

[0027] Aspect ratio = [(Length in the direction of microfibril extension (a)) / (Length in the direction of main chain extension (b))]

[0028] According to the fourth embodiment, in any one of the first to third embodiments,

[0029] Based on the total volume of the above pores, the volume of the above small pores may be 50% or more.

[0030] According to the fifth embodiment, in any one of the first to fourth embodiments,

[0031] Based on the total volume of the above pores, the volume of the above intermediate pores may be less than 50%.

[0032] According to the 6th embodiment, in any one of the 1st to 5th embodiments,

[0033] Based on the total volume of the above pores,

[0034] The volume of the above small pores is 60% or more, and

[0035] The volume of the above medium-sized pore may be 30% or less.

[0036] According to the seventh embodiment, in any one of the first to sixth embodiments,

[0037] The porosity of the above porous polymer matrix may be 40 volume% to 70 volume%.

[0038] According to the eighth embodiment, in any one of the first to seventh embodiments,

[0039] The thickness of the porous polymer matrix may be 5 μm to 14 μm.

[0040] According to the ninth embodiment, in any one of the first to eighth embodiments,

[0041] It further comprises a porous coating layer formed on at least one surface of the porous polymer matrix, and

[0042] The porous coating layer may include inorganic particles and binder polymers.

[0043]

[0044] According to another aspect of the present invention, electrochemical elements of the following embodiments are provided.

[0045] The electrochemical device according to the 10th embodiment is,

[0046] A separator according to any one of the first to ninth embodiments,

[0047] A first electrode and a second electrode provided on each side of the above-mentioned separator,

[0048] Electrolytes, and

[0049] It may include cases that accommodate these.

[0050]

[0051] According to another aspect of the present invention, a method for manufacturing a separation membrane of the following embodiments is provided.

[0052] The method for manufacturing a separation membrane according to the 11th embodiment is,

[0053] The method includes a process for obtaining a porous polymer matrix, and

[0054] The process of obtaining the above porous polymer matrix may include the following steps.

[0055] (S1) A step of feeding a polyolefin resin into an extruder to obtain an extruded product,

[0056] (S2) A step of obtaining a polymer sheet by thermoforming the above extruded product,

[0057] (S3) A step of stretching the polymer sheet at a low temperature, followed by stretching at a high temperature, and

[0058] (S4) A step of heat-treating the stretched sheet.

[0059] In the above (S3) step, low-temperature stretching and high-temperature stretching are each performed in directions parallel to each other as uniaxial stretching processes, and

[0060] The above low-temperature stretching is performed at a stretching ratio of 50% or more compared to the high-temperature stretching ratio, and

[0061] The above stretching ratio is the ratio of the length of the polymer sheet after stretching to the length of the polymer sheet before stretching.

[0062] According to the 12th embodiment, in the 11th embodiment,

[0063] The above low-temperature elongation ratio may be 1.05 times or more.

[0064] According to the 13th embodiment, in the 11th embodiment or the 12th embodiment,

[0065] The above low-temperature elongation ratio may be 1.1 times or more.

[0066] According to the 14th embodiment, in any one of the 11th to 13th embodiments,

[0067] The above thermoforming and heat treatment can each be performed at different temperatures.

[0068] According to the 15th embodiment, in any one of the 11th to 14th embodiments,

[0069] The above low-temperature stretching is performed at a temperature lower than the above thermoforming temperature, and

[0070] The above high-temperature stretching is performed at a temperature equal to or higher than the above thermoforming temperature, and

[0071] The above heat treatment can be performed at a higher temperature than the above high-temperature stretching.

[0072] According to the 16th embodiment, in any one of the 11th to 15th embodiments,

[0073] The process for obtaining the above porous polymer matrix may be a process that does not use one or more of a diluent and a plasticizer.

[0074] According to the 17th embodiment, in any one of the 11th to 16th embodiments,

[0075] The method may further include the step of forming a porous coating layer comprising inorganic particles and a binder polymer on at least one surface of the porous polymer matrix.

[0076] A separator according to one embodiment of the present invention can have the effect of significantly improving high-rate charging capacity by suppressing the generation of overvoltage during high-rate charging of an electrochemical device to which it is applied through a change in the characteristics of pores formed on the surface of a porous polymer matrix.

[0077] Furthermore, when charging in a CC-CV manner to increase the charging capacity of an electrochemical device using a separator according to one embodiment of the present invention, the ion transfer rate is increased due to the high pore volume within the porous polymer matrix of the separator, and accordingly, the charging capacity of the electrochemical device can be significantly improved.

[0078] An electrochemical device having a separator according to one embodiment of the present invention may exhibit an effect of having a charge / discharge output of 10 seconds or more at room temperature (23℃-25℃) and a charge / discharge output of 3 seconds or more at low temperature (5℃-10℃), but the present invention is not limited thereto.

[0079] Accordingly, an electrochemical device having a separator according to one aspect of the present invention has the advantage of being applicable to electric vehicles, hybrid vehicles, etc., that require rapid charging, but the effects of the present invention are not limited thereto.

[0080] Figure 1 shows a schematic diagram of the structure of a porous polymer matrix according to one embodiment of the present invention.

[0081] FIG. 2 shows a schematic diagram of the shape of pores in a porous polymer matrix according to one embodiment of the present invention.

[0082] The present invention will be described in detail below.

[0083] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0084] In this specification, the description of the term "A and / or B" means "A or B, or both."

[0085] Specific terms used in the following detailed description of the invention are for convenience only and are not intended to limit the invention. Additionally, words indicating direction, such as up, down, left, right, front, back, inside, and outside, indicate directions in the referenced drawings or directions toward or away from the geometric center of the respective designated device, system, and its components.

[0086] The present invention relates to a separator for an electrochemical device, a method for manufacturing the same, and an electrochemical device including the same.

[0087] 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 capable of charging and discharging and is a concept that encompasses lithium-ion batteries, nickel-cadmium batteries, nickel-hydrogen batteries, etc.

[0088] First, a separator for an electrochemical device according to one aspect of the present invention will be described in detail.

[0089]

[0090] Separator

[0091] A separation membrane according to one aspect of the present invention comprises a porous polymer matrix comprising a polyolefin-based resin.

[0092] In one embodiment of the present invention, the polyolefin resin may be used without particular limitation as long as it is a polyolefin-based resin used as a raw material for a separator for an electrochemical device. For example, the polyolefin resin may be polyethylene resin, polypropylene resin, polyethylene-polypropylene copolymer resin, or a mixture thereof without limitation.

[0093] According to one embodiment of the present invention, the polyolefin-based resin may include polypropylene resin in terms of the mechanical strength of the porous polymer matrix.

[0094] In one embodiment of the present invention, when the porous polymer matrix comprises polypropylene resin as a polyolefin-based resin, the polypropylene resin may be included in an amount of 50 weight% or more based on the total weight of the porous polymer matrix. Specifically, based on the total weight of the porous polymer matrix, the weight of the polypropylene resin may be 70 weight% or more, 80 weight% or more, 90 weight% or more, or 95 weight% or more. For example, based on the total weight of the porous polymer matrix, the weight of the polypropylene resin may be 98 weight% or more, 99 weight% or more, 99.9 weight% or more, or 100 weight%.

[0095] In one embodiment of the present invention, the porous polymer matrix may comprise only polypropylene resin as the polyolefin-based resin, but the present invention is not limited thereto.

[0096] In this specification, the weight of the polypropylene resin in the porous polymer matrix can be measured according to known methods for measuring the weight of polymer materials, and is not particularly limited to such methods. For example, the weight percentage of the polypropylene resin contained in the porous polymer matrix can be measured by measuring the mass change occurring while heating the sample using a known thermogravimetric analysis (TGA), but the present invention is not limited thereto. As for the TGA analysis method, for example, it can be performed using a SINCO TGA N-1000 (SINCO) instrument while using nitrogen or air as a purge gas and increasing the temperature in the range of 20°C to 950°C at a rate of 0.01°C / min to 300°C / min, but the present invention is not limited thereto.

[0097] In one embodiment of the present invention, the porous polymer matrix may be manufactured through a dry process using the polyolefin-based resin.

[0098] Accordingly, the porous polymer matrix may have a structure comprising a main chain of the polyolefin resin, microfibrils extending in one direction not parallel to the direction in which the main chain extends, and pores formed between the microfibrils.

[0099] FIG. 1 illustrates a schematic diagram of the structure of a porous polymer matrix according to one embodiment of the present invention. Referring to FIG. 1, the porous polymer matrix (200) has a structure comprising a main chain (201) of a polyolefin resin, microfibrils (202) extending in one direction not parallel to the direction (l) in which the main chain extends, and pores (203) formed between the microfibrils.

[0100] According to one embodiment of the present invention, when a polyolefin sheet is stretched during the preparation of the porous polymer matrix, microfibrils are extended and formed in the stretching direction from the polyolefin main chain, and a structure in which pores are formed between the microfibrils may appear, but the present invention is not limited thereto.

[0101] According to one embodiment of the present invention, a direction not parallel to the direction in which the main chain extends, i.e., the direction in which the microfibrils extend, may be a direction parallel to the stretching direction during the manufacture of the porous polymer matrix.

[0102] For example, when the polymer sheet is uniaxially stretched in the machine direction (MD) during the manufacture of the porous polymer matrix, it may be preferable for the direction in which the microfibrils extend to be formed in a direction parallel to the machine direction (MD).

[0103] In this specification, the term "machine direction" refers to a direction parallel to the driving direction of the manufacturing process of the porous polymer matrix. The machine direction can be identified through the fiber orientation direction of the polymer. For example, when the porous polymer matrix is ​​uniaxially stretched in the machine direction, the direction in which the microfibrils extend is parallel to the machine direction, and when the porous polymer matrix is ​​uniaxially stretched in the transverse direction (TD), the direction in which the microfibrils extend may be parallel to the transverse direction (TD) perpendicular to the machine direction. The fiber orientation direction of the polymer can be identified through optical microscope (e.g., SEM) observation of the surface of the porous polymer matrix, but the measurement method is not limited thereto.

[0104] According to one embodiment of the present invention, the porous polymer matrix is ​​preferably manufactured by uniaxial stretching in terms of mechanical strength, and accordingly, the pores formed between the microfibrils may include an elliptical shape having a cross-sectional shape that is long in the stretching direction.

[0105] For example, the cross-section of the pore formed between the microfibrils may include an elliptical shape with an aspect ratio greater than 1 according to Formula 1 below.

[0106] [Equation 1]

[0107] Aspect ratio = [(Length in the direction of microfibril extension (a)) / (Length in the direction of main chain extension (b))]

[0108] FIG. 2 illustrates a schematic diagram of the shape of a pore (203) according to one embodiment of the present invention. FIG. 2 indicates a direction (a) in which a microfibril extends and a direction (b) in which a main chain extends. The pore may include an elliptical shape with an aspect ratio greater than 1, for example, 3 to 100, 5 to 50, 5 to 30, or 10 to 20, but the present invention is not limited thereto.

[0109] In this specification, the aspect ratio of the pores between the microfibrils may be measured using an SEM image of the surface of the separation membrane or porous polymer matrix, but the measurement method is not limited thereto.

[0110] As described above, according to one embodiment of the present invention, the porous polymer matrix has a structure comprising a main chain of the polyolefin resin, microfibrils extending in one direction not parallel to the direction in which the main chain extends, and pores formed between the microfibrils, and the cross-section of the pores may comprise an elliptical shape having an aspect ratio greater than 1 according to Formula 1.

[0111] According to one embodiment of the present invention, the porous polymer matrix comprises pores having various sizes. In this specification, the pores within the porous polymer matrix may be broadly classified into ultra-micro pores, micro pores, meso pores, and macro pores according to their diameter.

[0112] Specifically, in this specification, pores with a diameter of less than 20 nm can be classified as micropores, pores with a diameter of 20 nm or more and less than 40 nm as micropores, pores with a diameter of 40 nm or more and less than 60 nm as mesopores, and pores with a diameter of 60 nm or more as large pores.

[0113] At this time, according to one aspect of the present invention, the porous polymer matrix is ​​characterized in that the total volume of the micropores is larger than the total volume of the mesopores.

[0114] According to one embodiment of the present invention, the porous polymer matrix comprises a plurality of pores. If the pore size is too small, the lithium ion and electron transportability is reduced, causing a problem of increasing the resistance value of the battery. Furthermore, the separator according to one embodiment of the present invention may have a porous coating layer comprising inorganic particles and a binder polymer on at least one surface of the porous polymer matrix. If the pore size of the porous polymer matrix is ​​too large, the inorganic particles and / or the binder polymer are impregnated in large quantities into the porous polymer matrix through the pores, thereby increasing the resistance of the separator and causing a problem of degrading the output performance of the battery.

[0115] Accordingly, according to one embodiment of the present invention, a porous polymer matrix having a specified total volume ratio of micropores and mesopores is used to solve the above-mentioned problem and to increase lithium ion and electron transportability while preventing an increase in the resistance of the separator.

[0116] In this specification, the diameters of each of the micropores, micropores, mesopores, and large pores within the porous polymer substrate can be measured, for example, using a water intrusion type Aqua pore instrument (Poretech Instrument, WMI-5K). Specifically, the diameter of the pores filled with water at a constant pressure can be measured according to ASTM D 4284-92 standards.

[0117] In addition, the volume ratio between each pore can also be measured using a water intrusion type Aqua pore device (Poretech Instrument, WMI-5K). Specifically, water is injected at a constant rate to achieve a water saturation of 100% in the porous polymer matrix to obtain a pore size-water saturation graph, and the volume of each pore can be calculated by summing the volume of water filled within each pore size range. Next, the volume ratio according to the pore diameter can be calculated by calculating the ratio between the calculated pore volumes.

[0118] According to one aspect of the present invention, the porous polymer matrix has pore characteristics in which the total volume of micropores having a diameter of 20 nm or more and less than 40 nm is larger than the total volume of mesopores having a diameter of 40 nm or more and less than 60 nm.

[0119] In one embodiment of the present invention, the pore structure of the porous polymer matrix within the separator can affect the charge capacity of the electrochemical device. When the total volume of micropores within the porous polymer matrix is ​​larger than the total volume of mesopores, more ions enter the active material lattice when the electrochemical device is charged, thereby exhibiting a more advantageous effect in terms of increasing the charge capacity of the electrochemical device when charged under the same conditions; however, the mechanism of the present invention is not limited thereto.

[0120] In one embodiment of the present invention, the volume of the micropores may be, for example, 50% or more based on the total volume of the pores. Specifically, it may be 50% to 80%, 50% to 75%, 55% to 75%, 60% to 75%, 60% to 70%, or 65% to 70%. For example, the volume of the micropores may be 68% to 70% or 68.7% to 70%, but the present invention is not limited thereto.

[0121] In one embodiment of the present invention, the volume of the micropores may be, for example, less than 50% or 48% or less based on the total volume of the pores. Specifically, it may be 10% to 45%, 15% to 40%, 20% to 35%, 20% to 30%, or 25% to 30%. For example, the volume of the medium pores may be 28% to 35% or 29.7% to 30%, but the present invention is not limited thereto.

[0122] In one embodiment of the present invention, based on the total volume of the pores, the volume of the small pores may be 60% or more, and the volume of the medium pores may be 30% or less. Specifically, the volume of the small pores may be 60% to 70%, and the volume of the medium pores may be 25% to 30%, but the present invention is not limited thereto.

[0123] In one embodiment of the present invention, it may be desirable for the porous polymer matrix having the pore characteristics described above to maintain appropriate mechanical strength in the membrane by maintaining the typical porosity of the porous polymer matrix within the membrane. For example, the porosity of the porous polymer matrix may be 40 volume% to 70 volume%, specifically 45 volume% to 60 volume% or 45 volume% to 50 volume%, but the present invention is not limited thereto.

[0124] The porosity of the above-mentioned porous polymer matrix may be measured by a conventional method for measuring the porosity of a separation membrane, for example, by measuring the total volume of pores filled with water at a constant pressure according to ASTM D 4284-92 standards. For example, the porosity may be measured by measuring the total volume of water filled in the porous polymer matrix while continuously applying pressure between 150 and 2,500 psi using a water intrusion type Aqua pore instrument (Poretech Instrument, WMI-5K), but the method of measuring the porosity is not limited to this.

[0125] In one embodiment of the present invention, the porous polymer matrix may have a thickness of, for example, 5 μm to 14 μm. Specifically, the thickness of the porous polymer matrix may be, for example, 8 μm to 14 μm, 8 μm to 12 μm, 10 μm to 12 μm, or 11 μm to 12 μm, but the thickness is not limited thereto.

[0126] According to one embodiment of the present invention, the separation membrane may not have a coating layer comprising inorganic particles and a binder polymer, and may use only the porous polymer matrix alone. That is, the separation membrane may be composed solely of the porous polymer matrix.

[0127] According to one embodiment of the present invention, the separation membrane may further comprise a porous coating layer comprising inorganic particles and / or a binder polymer on at least one surface of the porous polymer matrix.

[0128] According to another embodiment of the present invention, the separator may consist only of the porous polymer matrix and the binder adhesive layer.

[0129] According to another embodiment of the present invention, the separator may comprise the porous polymer matrix, a porous coating layer formed on at least one surface of the porous polymer matrix and comprising inorganic particles and / or a binder, and a binder adhesive layer formed on one surface of the coating layer and comprising only a binder. Here, the one surface of the porous coating layer refers to the surface that the separator and the electrode face when the separator is bonded to the electrode.

[0130] In one embodiment of the present invention, the separator may comprise the porous polymer matrix, a porous coating layer formed on at least one surface of the porous polymer matrix and comprising only inorganic particles, and a binder adhesive layer formed on one surface of the porous coating layer and comprising only a binder. Here, the one surface of the porous coating layer refers to the surface that the separator and the electrode face when the separator is bonded to the electrode.

[0131] In one embodiment of the present invention, the porous coating layer may include a large amount of inorganic particles and a binder polymer that binds them to improve the safety of the separation membrane. The inorganic particles may improve the heat resistance of the separation membrane, and the binder polymer may provide adhesion to the surface of the separation membrane.

[0132] At this time, if the pore characteristics of the porous polymer matrix in which the porous coating layer is formed consist only of polymer fibers without large pores having the size described above, or if the total volume of large pores is small and the polymer fibers are formed too densely, not only will the resistance of the separator increase, but the amount of slurry for forming the porous coating layer impregnated into the porous polymer matrix will decrease, and there may be a problem of inferior adhesion strength at the interface between the porous polymer matrix and the porous coating layer, but the present invention is not limited thereto.

[0133] The composition of the porous coating layer described above is explained exemplarily below. However, the composition of the porous coating layer is not limited thereto.

[0134] In one embodiment of the present invention, the porous coating layer may comprise inorganic particles and / or a binder polymer, wherein the inorganic particles have all or at least a portion of their surface coated by the binder polymer. In this case, the inorganic particles are surface-bonded and / or point-bonded via the binder polymer.

[0135] For example, the inorganic particles and binder resin in the porous coating layer may be included in a weight ratio of 95:5 to 70:30. The porous coating layer has a plurality of micropores inside, and these micropores are interconnected in a structure, and has the structural characteristics of a porous layer in which gas or liquid can pass from one side to the other.

[0136] In one embodiment of the present invention, the porous coating layer may be formed through a Safety Reinforced Separator (SRS) manufacturing method, a Ceramic Coated Separator (CCS) manufacturing method, or other known manufacturing methods, but the present invention is not limited thereto.

[0137] In one embodiment of the present invention, the porous coating layer may have a multilayer structure comprising a first layer adjacent to the porous polymer matrix containing inorganic particles, and a second layer located on the first layer containing a binder polymer, but the present invention is not limited thereto.

[0138] In one embodiment of the present invention, the inorganic particles may be used without particular limitation 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+). Non-limiting examples of such inorganic particles include BaTiO3, Pb(Zr,Ti)O3 (PZT), and 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 Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, and TiO2, and one or more of these may be included.

[0139] In one embodiment of the present invention, the average particle size (D) of the inorganic particles 50 ) may preferably be, for example, 100 nm or more. Specifically, the average particle size (D) of the inorganic particles. 50 The average particle size of the inorganic particles may be 100 nm to 1 μm, or 100 nm to 500 nm. When the average particle size of the inorganic particles is within the range described above, it may exhibit an advantageous effect in terms of suppressing the increase in resistance of the separation membrane, but the present invention is not limited thereto.

[0140] The particle size of the above-mentioned inorganic particles can be measured by known particle size measurement methods, for example, using a Particle Size Analyzer (PSA) from Melbourne. In addition, the above-mentioned average particle size (D 50) refers to the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size, and may be measured through a known laser diffraction method. In this case, the laser diffraction particle size measuring device may use, for example, the Microtrac S3500 from Microtrac Corporation.

[0141] In one embodiment of the present invention, the binder polymer may comprise, for example, a polyvinylidene fluoride-based resin (PVdF-based resin). In one embodiment of the present invention, the PVdF-based resin may comprise one or more of a homopolymer of vinylidene fluoride (i.e., polyvinylidene fluoride), a copolymer of vinylidene fluoride with a monomer capable of copolymerizing with vinylidene fluoride, and a mixture thereof. In one embodiment of the present invention, the monomer may be, 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); and hexafluoropropylene (HFP). Perfluoro(alkylvinyl) ethers such as perfluoro(methylvinyl) ether (PMVE), perfluoro(ethylvinyl) ether (PEVE), and perfluoro(propylvinyl) ether (PPVE); perfluoro(1,3-dioxol); and perfluoro(2,2-dimethyl-1,3-dioxol) (PDD), etc., and one or more of these may be included.

[0142] In one embodiment of the present invention, the binder polymer may include, but is not limited to, an oil-based binder, a water-based binder, or a mixture thereof that can be used in a porous coating layer.

[0143] In one embodiment of the present invention, the total thickness of the porous coating layer formed in the separator may be, for example, 0.5 to 50 μm, specifically 0.5 to 10 μm, 0.5 to 5 μm, or 3 to 4.5 μm, but the present invention is not limited thereto.

[0144]

[0145] Method for manufacturing a separation membrane

[0146] According to another aspect of the present invention, an example of a method for manufacturing the above-described separation membrane is provided.

[0147] The above method for manufacturing the separation membrane is merely an example of the method for manufacturing the separation membrane described above, and the above method for manufacturing the separation membrane is not limited to the method described below.

[0148] A method for manufacturing a separation membrane according to one aspect of the present invention comprises obtaining a porous polymer matrix by a dry process.

[0149] Specifically, in this specification, the dry process describes a method of melting a polymer resin using an extruder, extruding the molten resin to form a film, and then forming pores through stretching.

[0150] More specifically, the above dry process may represent a process that does not use one or more of the diluent and plasticizer used to form pores on a polymer film in a conventional wet process, preferably the diluent and plasticizer. By doing so, the mixing and extraction processes of the diluent used in the conventional wet process are also excluded, thereby providing an environmentally friendly manufacturing method, but the present invention is not limited thereto.

[0151] According to one embodiment of the present invention, the process of obtaining the porous polymer matrix may include the following steps.

[0152] (S1) A step of feeding a polyolefin resin into an extruder to obtain an extruded product,

[0153] (S2) A step of obtaining a polymer sheet by thermoforming the above extruded product,

[0154] (S3) A step of stretching the polymer sheet at a low temperature, followed by stretching at a high temperature, and

[0155] (S4) A step of heat-treating the stretched sheet.

[0156] In one embodiment of the present invention, the porous polymer matrix may consist solely of polypropylene resin in terms of mechanical strength. To this end, the polyolefin-based resin may include polypropylene resin, and step (S1) may include the step of introducing polypropylene resin into an extruder and melt-kneading it.

[0157] According to one embodiment of the present invention, a polymer sheet can be obtained by extruding a melt-mixed polyolefin resin through step (S1) and molding the extruded product through step (S2). For the extrusion, a flat die such as a T die or a coat hanger die may be used, and a roll-to-roll molding machine may be used for the molding.

[0158] Next, the molded polymer sheet can be stretched at least twice under different temperature conditions.

[0159] Specifically, the above step (S3) includes the step of stretching the polymer sheet at a low temperature (low-temperature stretching) and then stretching it at a high temperature (high-temperature stretching). The above step (S2) can increase the amount of pores formed by rapidly cooling the polymer sheet by first stretching the obtained polymer sheet at a low temperature, and then increase the size of the pores formed during low-temperature stretching by performing secondary stretching at a higher temperature. At this time, the volume of micropores within the polymer sheet can be increased by performing the stretching ratio of the low-temperature stretching at 50% or more compared to the stretching ratio of the high-temperature stretching, but the mechanism of the present invention is not limited thereto.

[0160] In one embodiment of the present invention, the mechanical strength and puncture strength of the polymer sheet can be improved through the stretching process.

[0161] At this time, according to one embodiment of the present invention, the porous polymer matrix is ​​uniaxially stretched, and it is preferable that the low-temperature stretching and the high-temperature stretching be performed in directions parallel to each other. More specifically, the low-temperature stretching and the high-temperature stretching may each be performed in the machine direction (MD).

[0162] In one embodiment of the present invention, the stretching can be performed by a roll method or a tenter method, sequentially or simultaneously.

[0163] According to one aspect of the present invention, in order to increase the volume of micropores while maintaining mechanical strength without changing the porosity of the obtained porous polymer matrix, low-temperature stretching is performed at a stretching ratio of 50% or more compared to the high-temperature stretching ratio.

[0164] In the present specification, the 'stretch ratio' in step (S3) represents the ratio of the length of the polymer sheet after stretching to the length of the polymer sheet before stretching. That is, the stretch ratio can be calculated as the ratio of (length of the polymer sheet after stretching / length of the polymer sheet before stretching).

[0165] In one embodiment of the present invention, the low-temperature stretching may be a decisive step in determining the number of pores within the porous polymer matrix being formed. Specifically, after the polyolefin sheet is obtained, the initial stretching process is performed at a low temperature to tear the amorphous structure of the fibers and form micropores. At this time, if the low-temperature stretching ratio is too large, the polyolefin sheet may tear or damage may occur in terms of the porosity of the porous polymer matrix being formed; therefore, it may be desirable to perform the low-temperature stretching ratio in a range smaller than the high-temperature stretching ratio. However, if the low-temperature stretching ratio is too small, the number of pores formed decreases and the porosity of the porous polymer matrix is ​​reduced, or problems may arise where the porous polymer matrix is ​​fractured by increasing the high-temperature stretching ratio to achieve a porosity above a certain level. Accordingly, it may be desirable to perform the low-temperature stretching ratio in a range of 50% to 100% relative to the high-temperature stretching ratio.

[0166] In one embodiment of the present invention, the high-temperature stretching may be a decisive step in determining the size of pores within a porous polymer matrix. Specifically, by additionally stretching a sheet in which micropores are formed during a low-temperature stretching process at a high temperature, the size of the already formed micropores is increased, and micropores, micropores, mesopores, and large pores can be formed depending on the stretching ratio.

[0167] In one embodiment of the present invention, the high-temperature stretching ratio may be performed at 2 times or more, for example, 2.0 times to 2.1 times, but the present invention is not limited thereto.

[0168] In one embodiment of the present invention, the low-temperature stretching ratio may be performed at a range of 1.05 times or more, for example 1.1 times or more, specifically 1.1 times to 1.5 times, but the present invention is not limited thereto.

[0169] In one embodiment of the present invention, the stretching temperature may vary depending on the melting point of the polymer used, for example, polypropylene resin, and the present invention is not limited thereto.

[0170] In one embodiment of the present invention, in order to increase the volume of micropores relative to the volume of mesopores of the porous polymer matrix being manufactured, the thermoforming and heat treatment as processes before and after the stretching step (S3) may each be performed at different temperatures.

[0171] In particular, in one embodiment of the present invention, the low-temperature stretching may be performed at a temperature lower than the thermoforming temperature of the preceding stage, and the high-temperature stretching may preferably be performed at a temperature higher than the low-temperature stretching of the preceding stage. Specifically, the high-temperature stretching may be performed at a temperature equal to or higher than the thermoforming temperature of the preceding stage, and more specifically, the high-temperature stretching may be performed at a temperature higher than the thermoforming temperature, but the present invention is not limited thereto.

[0172] Furthermore, in one embodiment of the present invention, the heat setting is a process for removing residual stress within the polymer sheet after stretching, and it may be preferable to perform it at a higher temperature than the preceding thermoforming, low-temperature stretching, and high-temperature stretching processes.

[0173] According to one embodiment of the present invention, the step (S1) may be performed at a temperature of 200°C or higher to melt the polyolefin resin.

[0174] According to one embodiment of the present invention, the subsequent step (S2) may be performed at a temperature of, for example, 200°C or lower, specifically 140°C to 200°C, 150°C to 195°C, 160°C to 200°C, 170°C to 190°C, or 180°C to 185°C, so that the extruded product obtained can be formed into a sheet shape.

[0175] According to one embodiment of the present invention, the low-temperature stretching of step (S3) may be performed at a temperature of, for example, 90°C to 140°C or 90°C to 135°C, for example, 90°C to 120°C, 95°C to 110°C, or 100°C to 110°C in order to increase the amount of pores formed while rapidly cooling the thermoformed polymer sheet.

[0176] According to one embodiment of the present invention, the high-temperature stretching of step (S3) may be performed at a temperature of, for example, 140°C to 160°C, for example, 140°C to 150°C, or 145°C to 150°C in order to increase the pore size by secondarily stretching the low-temperature stretched polymer sheet at a higher temperature.

[0177] According to one embodiment of the present invention, step (S4) may be heat-setting at a higher temperature than the temperatures of (S1) to (S3) to remove residual stress in the stretched polymer sheet and increase mechanical strength, and the heat-setting temperature may be performed, for example, at 150°C to 170°C, 150°C to 165°C, 150°C to 160°C, or 155°C to 160°C, but the present invention is not limited thereto.

[0178] According to one embodiment of the present invention, the method for manufacturing the separation membrane may further include the step of forming a porous coating layer, which includes the step of forming a porous coating layer on at least one surface of the porous polymer matrix after obtaining the porous polymer matrix (S5).

[0179] In one embodiment of the present invention, the step (S5) may include preparing a binder solution in which a binder polymer is dispersed in a solvent or dissolved, and then adding inorganic particles to the binder solution to prepare a slurry for forming a coating layer.

[0180] Non-limiting examples of solvents used in preparing the slurry for forming the coating layer include one or more mixtures selected from the group consisting of water, acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), and cyclohexane, but the present invention is not limited thereto.

[0181] In one embodiment of the present invention, the method of coating the slurry onto a porous polymer matrix may use conventional coating methods known in the art, such as dip coating, die coating, roll coating, comma coating, or a combination thereof. In addition, the drying may be performed using conventional drying methods, such as natural drying or air drying, without any particular limitations.

[0182]

[0183] Electrode assembly and electrochemical device

[0184] According to another aspect of the present invention, an electrode assembly is provided comprising the above-described separator, a first electrode and a second electrode formed on each side of the separator.

[0185] According to another aspect of the present invention, an electrochemical device is provided comprising the above-described separator, a first electrode and a second electrode provided on each of the two sides of the separator, an electrolyte, and a case for housing the same.

[0186] The first electrode and the second electrode may each be an anode or a cathode.

[0187] In one embodiment of the present invention, the positive and negative electrodes may each have an electrode active material coated on a current collector, or they may be in the form of a self-supporting metal plate or a film containing an active material without a current collector, and their size, shape, or type of active material is not particularly limited.

[0188] For example, an electrochemical device according to one embodiment of the present invention may include an NCM-based active material as a positive electrode and a graphite-based active material as a negative electrode, but the present invention is not limited thereto.

[0189] In one embodiment of the present invention, in terms of high-rate charging characteristics and output characteristics of the electrochemical device, the active material loading amount of the anode is, for example, 200 mg / 25 cm 2 Above, for example, 200 mg / 25 cm 2 Up to 280 mg / 25 cm 2 , 200 mg / 25 cm 2 Up to 220 mg / 25 cm 2, Specifically, 210 mg / 25 cm 2 to 215 mg / 25 cm 2 or 212 mg / 25 cm 2 It may be, but the present invention is not limited thereto.

[0190] In one embodiment of the present invention, in terms of high-rate charging characteristics and output characteristics of the electrochemical device, the active material loading amount of the negative electrode is, for example, 200 mg / 25 cm 2 Below, e.g., 100 mg / 25 cm 2 Up to 200 mg / 25 cm 2 , 100 mg / 25 cm 2 Up to 150 mg / 25 cm 2 , Specifically, 110 mg / 25 cm 2 to 130 mg / 25 cm2 , 120 mg / 25 cm 2 to 150 mg / 25 cm 2 or 121 mg / 25 cm 2 It may be, but the present invention is not limited thereto.

[0191] In addition, in one embodiment of the present invention, the electrochemical element may be an example of a primary battery, a secondary battery, a supercapacitor, an electric double layer capacitor, etc. More specifically, the secondary battery may be a lithium-ion secondary battery.

[0192] In one embodiment of the present invention, the case may be one that is conventionally used as a battery case, and is not particularly limited in its external shape according to the use of the battery. For example, the case may be a cylindrical, prismatic, pouch, or coin type using a can.

[0193] When the electrode assembly described above is completed, it can be housed in a case and sealed in a conventional manner to manufacture an electrochemical device, and the electrochemical device may be, for example, a lithium secondary battery.

[0194] As described above, a separator according to one aspect of the present invention is characterized by improving the ion transfer rate, thereby improving the charging capacity of an electrochemical device using the same. In addition, an electrode assembly and an electrochemical device using the separator may be characterized by suppressing the generation of overvoltage even during high-rate charging, so that they have a high capacity even during high-rate charging.

[0195]

[0196] The present invention will be described in more detail below through examples, but the following examples are intended to illustrate the invention and the scope of the invention is not limited thereto.

[0197] [Preparation of porous polymer matrix]

[0198] Comparative Example 1

[0199] Polypropylene (Daehan Petrochemical Co., S800M, MI 1.5) was fed and melted as a raw material into an extruder (Korea EM, φ32 uniaxial extruder L / D=40) and an extruded product was obtained at 230°C.

[0200] A porous polymer matrix with a thickness of 12 μm (porosity 50 vol%) was prepared by thermoforming a polypropylene extruder into a sheet shape at a temperature range of 185°C using a roll-to-roll uniaxial stretcher, then performing a first stretching at a stretching ratio of 1.04 times in a low-temperature stretching range of 100°C, then performing a second stretching at a stretching ratio of 2.1 times in a high-temperature stretching range of 145°C, and finally heat-setting at a temperature of 155°C (stretch ratio = 0.95). That is, the stretching process was performed such that the stretching ratio calculated according to the formula [(low-temperature stretching ratio) / (high-temperature stretching ratio)] was 49.52%.

[0201]

[0202] Example 1

[0203] In the process of manufacturing the above porous polymer matrix, a porous polymer matrix with a thickness of 12 μm (porosity 50 vol%) was prepared in the same manner as Comparative Example 1, except that a first stretching was performed at a stretching ratio of 1.1 times in the low-temperature stretching section. That is, the stretching process was performed so that the stretching ratio calculated according to the formula [(low-temperature stretching ratio) / (high-temperature stretching ratio)] was 52.40%.

[0204]

[0205] [Evaluation of Physical Properties of Porous Polymer Matrix]

[0206] The properties of the porous polymer matrix obtained above were evaluated by the following method.

[0207] Measurement of the thickness (L) of the porous polymer matrix

[0208] The thickness of the separator substrate was measured using a thickness gauge from Mitutoyo.

[0209]

[0210] Measurement of porosity of a porous polymer matrix

[0211] The diameter of the pores filled with water at a constant pressure was measured according to ASTM D 4284-92. The porosity was determined by continuously applying pressure in the range of 150 to 2,500 psi, measuring the pore size at each constant pressure, and measuring the volume of water filled in the porous polymer matrix.

[0212] The measurement is performed automatically, and the calculated value is output. The equipment used was a water intrusion type Aqua pore instrument (Poretech Instrument, WMI-5K), and the measurable pore size range was from 10 nm to 130 nm.

[0213]

[0214] Measurement of the ratio of micropores and mesopores in a porous polymer matrix

[0215] The ratios of micropores and mesopores within a porous polymer matrix were measured using a water intrusion type Aqua pore instrument (Poretech Instrument, WMI-5K) under conditions of 150–2,500 psi, surface tension of 72 N / m (20℃), and contact angle of 120°. The ratio of micropores represents the ratio of the total volume of micropores with a diameter of 20 nm or more and less than 40 nm to the total volume of pores within the porous polymer matrix, and the ratio of mesopores represents the ratio of the total volume of mesopores with a diameter of 40 nm or more and less than 60 nm to the total volume of pores within the porous polymer matrix.

[0216]

[0217] The results of the physical property evaluation measured above are shown in Table 1 below.

[0218] Thickness (㎛) Porosity (vol%) Micropores (%) Mediumpores (%) Comparative Example 1 125029.753.7 Example 1 125068.723.4

[0219] As confirmed by the above results, it was confirmed that the membrane substrate according to Example 1 is implemented with a much higher ratio of micropores and a much smaller ratio of medium pores while maintaining thickness and porosity compared to Comparative Example 1.

[0220]

[0221] [Evaluation of Battery Physical Properties]

[0222] A lithium secondary battery was manufactured using the porous polymer matrix prepared above by the following method, and the physical properties of the manufactured battery were evaluated as follows.

[0223]

[0224] Preparation of coating separator

[0225] A porous coating layer was formed on both sides of the porous polymer matrix prepared above, in which an inorganic layer and a binder layer were sequentially formed by the following method.

[0226] First, an alumina dispersion (solid content 95 wt%) in which alumina is dispersed in water was applied to both sides of the porous polymer matrix and dried to form an inorganic layer with a thickness of 1.5 μm on each side. Subsequently, a PVDF binder solution (solid content 80 wt%) dissolved in acetone was applied onto the inorganic layer and dried to form a binder layer with a thickness of 0.75 μm on each side. The total thickness of the porous coating layer formed on both sides was 4.5 μm.

[0227]

[0228] Preparation of the anode

[0229] Cathode active material (LiNi 0.8 Mn 0.1 Co 0.1O2), a conductive material (carbon black), and a binder resin (PVDF) were mixed with water in a weight ratio of 97.5:0.7:1.8 to prepare a slurry for an anode active material layer with a concentration of 50 wt% of the components excluding water. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to produce an anode having an anode active material layer (thickness 60 μm).

[0230]

[0231] Preparation of the cathode

[0232] A graphite-based active material, carbon black, carboxymethylcellulose (CMC), and binder resin (SBR) were mixed with water in a weight ratio of 97.5:0.7:1.1:0.7 to prepare a slurry for a negative electrode active material layer with a concentration of 50 wt% of the components excluding water. At this time, a 9:1 mixture of artificial graphite and natural graphite was used as the graphite-based active material. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to produce a negative electrode having a negative electrode active material layer (thickness 60 μm).

[0233]

[0234] Assembly of electrode assemblies

[0235] An electrode assembly was prepared by interposing the coating separator prepared above between the anode and cathode prepared above, and then laminating under conditions of 75°C, 9 MPa, and 1s.

[0236]

[0237] Manufacturing of lithium secondary batteries

[0238] The anode prepared above is 50 x 33 mm (width) x (height) 2 Die to the size of 51 x 34 mm (width) x (height). 2 Die-cut to the size of 56 x 39 mm (width) x (height). 2 After cutting to size, lamination was performed using the same method.

[0239] A monocell was prepared by placing a laminated electrode assembly into a pouch, injecting an electrolyte composed of 1M LiPF6, ethyl carbonate (EC) and ethylmethyl carbonate (EMC) (3 / 7 v / v), and 2 wt% vinylene carbonate (VC), and sealing it.

[0240]

[0241] Charging capacity evaluation

[0242] For the monocell prepared above, the CC capacity and CCCV capacity were each calculated by charging at a 3C-rate in CCCV mode (current 0.05C cut condition) and calculating the ratio of (CC charging capacity / CCCV charging capacity) x 100 (%).

[0243] 3C CC / CCCV Charging Capacity (%) Comparison Example 126 Example 133

[0244] As shown in the results above, it was confirmed that the CC capacity relative to the CCCV capacity of the battery of Example 1 increased by approximately 25% compared to the battery of Comparative Example 1. Through this, it was confirmed that according to one embodiment of the present invention, the overvoltage within the battery is reduced, which has an effect favorable to high-rate charging output characteristics.

[0245] [Explanation of the symbol]

[0246] 200: Porous polymer matrix

[0247] 201: Polyolefin main chain

[0248] 202: Microfibrils

[0249] 203: Qi Gong

[0250] a: Extension direction of microfibrils

[0251] b: Extension direction of the polyolefin main chain

[0252] MD: Machine direction

Claims

1. A porous polymer matrix comprising a polyolefin-based resin, and The above porous polymer matrix is, The main chain of the above polyolefin resin and, Micro fibrils extending in one direction not parallel to the direction in which the above-mentioned main chain extends, and It includes pores formed between the above microfibrils, The above pores include micropores having a diameter of 20 nm or more and less than 40 nm, and mesopores having a diameter of 40 nm or more and less than 60 nm, and A separator in which the total volume of the above small pores is larger than the total volume of the above medium pores.

2. In Claim 1, The above polyolefin-based resin includes polypropylene resin, and A separator having a polypropylene resin weight of 95% or more based on the total weight of the porous polymer matrix.

3. In Claim 1, A separation membrane in which the cross-section of the above pore comprises an elliptical shape having an aspect ratio greater than 1 according to Formula 1 below. [Equation 1] Aspect ratio = [(Length in the direction of microfibril extension (a)) / (Length in the direction of main chain extension (b))] 4. In Claim 1, A separation membrane in which the volume of the micropores is 50% or more based on the total volume of the pores.

5. In Claim 1, A separation membrane in which the volume of the intermediate pore is less than 50% based on the total volume of the above pores.

6. In Claim 1, Based on the total volume of the above pores, The volume of the above small pores is 60% or more, and A separator having a volume of 30% or less of the above intermediate pores.

7. In Claim 1, A separation membrane having a porosity of 40 volume% to 70 volume% of the porous polymer matrix.

8. In Claim 1, A separation membrane having a thickness of 5 μm to 14 μm of the porous polymer matrix.

9. In Claim 1, It further comprises a porous coating layer formed on at least one surface of the porous polymer matrix, and The above porous coating layer is a separation membrane comprising inorganic particles and a binder polymer.

10. A separator according to any one of claims 1 to 9, A first electrode and a second electrode provided on each side of the above-mentioned separator, Electrolytes, and Electrochemical device including a case that accommodates these.

11. A process for obtaining a porous polymer matrix, comprising, A method for manufacturing a separation membrane according to claim 1, wherein the process of obtaining the above porous polymer matrix comprises the following steps: (S1) A step of feeding a polyolefin resin into an extruder to obtain an extruded product, (S2) A step of obtaining a polymer sheet by thermoforming the above extruded product, (S3) A step of stretching the polymer sheet at a low temperature, followed by stretching at a high temperature, and (S4) A step of heat-treating the stretched sheet, In the above (S3) step, low-temperature stretching and high-temperature stretching are each performed in directions parallel to each other as uniaxial stretching processes, and The above low-temperature stretching is performed at a stretching ratio of 50% or more compared to the high-temperature stretching ratio, and The above stretching ratio is the ratio of the length of the polymer sheet after stretching to the length of the polymer sheet before stretching.

12. In Claim 11, A method for manufacturing a separator having a low-temperature stretching ratio of 1.05 times or more.

13. In Claim 11, A method for manufacturing a separator having a low-temperature stretching ratio of 1.1 times or more.

14. In Claim 11, A method for manufacturing a separator, wherein the thermoforming and heat treatment are each performed at different temperatures.

15. In Claim 11, The above low-temperature stretching is performed at a temperature lower than the above thermoforming temperature, and The above high-temperature stretching is performed at a temperature equal to or higher than the above thermoforming temperature, and A method for manufacturing a separator membrane, wherein the above heat treatment is performed at a higher temperature than the above high-temperature stretching.

16. In Claim 11, A method for manufacturing a separation membrane, wherein the process of obtaining the above porous polymer matrix is ​​a process that does not use one or more of a diluent and a plasticizer.

17. In Claim 11, A method for manufacturing a separation membrane, further comprising the step of forming a porous coating layer comprising inorganic particles and a binder polymer on at least one surface of the porous polymer matrix.

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