Separator for electrochemical device, electrochemical device including same, and method for manufacturing same

Abstract

The present disclosure relates to a separator for an electrochemical device, an electrochemical device including the same, and a method of manufacturing the same. The present invention relates to a separator for an electrochemical device, and more particularly, to a separator for an electrochemical device, an electrochemical device including the same, and a method for manufacturing the same, which can improve electrical resistance and maintain porosity after lamination by comprising a polyvinylidene-based binder containing a low content of hexafluoropropylene and / or a polyolefin-based binder.

Description

Technical Field

[0001] The present disclosure claims the benefit of the filing date of Korean Patent Application No. 10-2023-0026494 filed with the Korean Intellectual Property Office on February 28, 2023 and the filing date of Korean Patent Application No. 10-2024-0007841 filed with the Korean Intellectual Property Office on January 18, 2024, all of which are included in the present disclosure. The present disclosure relates to a separator for an electrochemical device, an electrochemical device including the same, and a method for manufacturing the same, and in particular, to a separator for an electrochemical device that can improve (reduce) resistance and maintain porosity after lamination by including a polyvinylidene-based binder containing a low content of hexafluoropropylene and / or a polyolefin-based binder, an electrochemical device including the same, and a method for manufacturing the same. Background Art

[0002] The separator in the components of the electrochemical device includes a polymer substrate with a porous structure located between the positive electrode and the negative electrode, and is used to separate the positive electrode and the negative electrode, prevent electrical short circuits between the two electrodes, and allow electrolyte and ions to pass through. The separator itself does not participate in the electrochemical reaction, but physical properties such as wettability to the electrolyte, porosity, thermal shrinkage, etc. affect the performance and safety of the electrochemical device.

[0003] Therefore, in order to enhance the physical properties of the separator, various methods of changing the physical properties of the coating by adding a coating to a porous polymer substrate and adding various materials to the coating have been tried. For example, an inorganic material can be added to the coating to improve (improve) the mechanical strength of the separator, or an inorganic material or hydrate can be added to the coating to improve the flame retardancy and heat resistance of the polymer substrate.

[0004] The separator may be combined with the electrode through a lamination process, and a binder resin may be added to a slurry for coating of the separator to ensure adhesion between the electrode and the separator.

[0005] Meanwhile, when an acrylic binder is included in the coating or a binder based on poly(vinylidene fluoride) (PVdF) is used, there is a problem of increased resistance. In addition, there is a problem that, during the lamination process of combining the electrode and the separator, the resistance at the coating interface increases due to the phenomenon that the binder included in the coating is formed into a film.

[0006] Therefore, research on a technology in which the porosity of the coating layer is not reduced and the resistance of the separator itself is not increased even if the lamination process is performed is required. Summary of the invention

[0007] Technical issues

[0008] The technical problem to be solved by the present disclosure is to provide a separator for an electrochemical device that overcomes the disadvantages of the prior art, in particular, can prevent an increase in interface resistance due to film formation of a binder contained in a coating layer that occurs in the step of laminating electrodes and separators during the process of manufacturing a secondary battery, and can prevent an increase in separator resistance due to the use of an acrylic binder, an electrochemical device including the same, and a method for manufacturing the same.

[0009] However, problems to be solved by the present disclosure are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

[0010] Technical Solution

[0011] One embodiment of the present disclosure provides a separator for an electrochemical device, the separator for an electrochemical device comprising: a porous polymer substrate; and a coating disposed on at least one surface of the porous polymer substrate, wherein the coating comprises a first polymer binder in particle form, a second polymer binder in particle form and inorganic particles, and the second polymer binder is selected from: a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of less than 10 wt % relative to the total weight of the polyvinylidene-based binder; a polyolefin-based binder; and combinations thereof.

[0012] According to one embodiment of the present disclosure, the amount of inorganic particles in the region of the coating adjacent to the porous polymer substrate may be greater than the amount of inorganic particles in the region of the coating opposite to the porous polymer substrate; the amount of the first polymer binder and the second polymer binder in the region of the coating adjacent to the porous polymer substrate may be less than the amount of the first polymer binder and the second polymer binder in the region of the coating opposite to the porous polymer substrate, wherein if the coating is divided into two halves relative to the thickness of the coating, the region of the coating adjacent to the porous polymer substrate is the half of the coating adjacent to the porous polymer substrate, and the region of the coating opposite to the porous polymer substrate is the half of the coating farther away from the porous polymer substrate.

[0013] According to one embodiment of the present disclosure, the coating may further include a region including the first polymer binder in the form of a film.

[0014] According to one embodiment of the present disclosure, the polyvinylidene-based binder may be a polyvinylidene fluoride-based binder.

[0015] According to one embodiment of the present disclosure, the polyolefin-based binder may be polyethylene.

[0016] According to one embodiment of the present disclosure, the first polymer binder may be selected from: an acrylic binder; a polyvinylidene-based binder; a hybrid binder including an acrylic binder and a polyvinylidene-based binder; and combinations thereof.

[0017] According to one embodiment of the present disclosure, the polyvinylidene-based binder may be a polyvinylidene fluoride-based binder.

[0018] According to one embodiment of the present disclosure, the total content of the first polymer binder and the second polymer binder in the coating may be 30 parts by weight or less based on 100 parts by weight of the coating.

[0019] According to one embodiment of the present disclosure, the total content of the inorganic particles in the coating layer is 70 parts by weight or more based on 100 parts by weight of the coating layer.

[0020] According to one embodiment of the present disclosure, the porosity of the coating may be 33 volume % or greater, preferably greater than 33 volume %.

[0021] According to one embodiment of the present disclosure, the polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % may be an aqueous binder.

[0022] According to one embodiment of the present disclosure, the dry adhesion of the coating layer may be 30 gf / 25 mm or more.

[0023] One embodiment of the present disclosure provides an electrochemical device including: a positive electrode, a negative electrode, and a separator, wherein the separator is the above separator for an electrochemical device, and the separator is interposed between the positive electrode and the negative electrode.

[0024] One embodiment of the present disclosure provides a method for manufacturing a separator for an electrochemical device, the method comprising the following steps: mixing a slurry for preparing a coating, the slurry for preparing the coating comprising a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles; applying the slurry for preparing the coating to at least one surface of a porous polymer substrate; and drying the slurry for preparing the coating to form a coating, wherein the second polymer binder is selected from: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 weight percent; a polyolefin-based binder; and combinations thereof.

[0025] According to one embodiment of the present disclosure, the step of performing mixing may be performing mixing for 1 hour or more and 3 hours or less.

[0026] According to one embodiment of the present disclosure, the first polymer binder may be one selected from the following: an acrylic binder; a polyvinylidene-based binder; a hybrid binder comprising an acrylic binder and a polyvinylidene-based binder; and a combination thereof, and the drying is drying carried out at a temperature that differs from the glass transition temperature of the first polymer binder by no more than 20°C.

[0027] Beneficial Effects

[0028] In the separator for an electrochemical device according to one embodiment of the present disclosure, the porosity does not decrease even after lamination with an electrode, and an increase in the resistance of the separator can be prevented.

[0029] An electrochemical device according to one embodiment of the present disclosure may improve energy efficiency by reducing the resistance of a separator.

[0030] The method for manufacturing an electrochemical device according to one embodiment of the present disclosure may easily prevent an increase in resistance of a separator and may enable polymer binder particles to support pressure applied during lamination with an electrode, thereby preventing a decrease in porosity of the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram showing that the porosity of a separator for an electrochemical device according to one embodiment of the present disclosure is maintained after lamination.

[0032] Figure 2 is a flow chart of a method for manufacturing a separator for an electrochemical device according to one embodiment of the present disclosure.

[0033] Figure 3 is a schematic diagram of an electrochemical device according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] Hereinafter, multiple embodiments of the present disclosure will be described in detail so that those skilled in the art to which the present disclosure belongs can easily implement the present disclosure. However, these are merely examples given for illustrative purposes, and the scope of the present disclosure is not intended to be limited to the following.

[0035] Unless otherwise limited, the detailed description of the defined or specified elements can be applied to all inventions and is not limited to the description of a specific invention. That is, the present disclosure also relates to a combination of embodiments, even if they are disclosed separately. In addition, unless otherwise explicitly stated, throughout the detailed description and the appended claims, the singular includes the plural.

[0036] In this specification, when a part is said to "comprise" a certain component, unless otherwise clearly stated, this means that it may also include other components, without excluding other components. However, unless otherwise clearly stated, "comprising" or "including" etc. include "essentially comprising" and "consisting of...".

[0037] As used herein, the term "essentially comprising" has the meaning of "comprising at least 70%", preferably the meaning of "comprising at least 80%", most preferably the meaning of "comprising at least 90%. If referring to the amount of a component in a mixture of materials, the % is the % by weight relative to the total weight of the respective mixture. For example, a material essentially comprising polyethylene comprises polyethylene in an amount of at least 70 % by weight relative to the total weight of the material.

[0038] In the present specification, "A and / or B" means "A and B, or A or B".

[0039] In this specification, when a component is referred to as being disposed "on" another component, unless otherwise explicitly stated, this does not exclude that another component is disposed therebetween, but means that another component may also be disposed therebetween. However, unless otherwise explicitly stated, "on..." encompasses the meaning of "directly on...", that is, the case where no other component may be further disposed therebetween.

[0040] In this specification, the property of "having pores" or "porous" means that the object contains a plurality of pores, and thus gas phase fluid and / or liquid phase fluid can pass from one side of the object to the other side thereof through a structure in which the pores are connected to each other.

[0041] In this specification, the separator has a porous property including a plurality of pores, and serves as a porous ion-conducting barrier to allow ions to pass therethrough while blocking electrical contact between a negative electrode and a positive electrode in an electrochemical device.

[0042] Hereinafter, the present disclosure will be described in more detail.

[0043] One embodiment of the present disclosure provides a separator 100 for an electrochemical device, comprising: a porous polymer substrate 110 and a coating 130. The coating 130 is disposed on at least one surface of the porous polymer substrate 110, that is, disposed on one surface or both surfaces of the porous polymer substrate 110. The coating 130 comprises a first polymer binder 131 in the form of particles, a second polymer binder 133 in the form of particles, and inorganic particles 135, wherein the second polymer binder 133 is selected from: a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of less than 10 wt% relative to the total weight of the polyvinylidene-based binder; a polyolefin-based binder; and combinations thereof.

[0044] In the separator 100 for an electrochemical device according to one embodiment of the present disclosure, the porosity does not decrease even after lamination with an electrode, and an increase in the resistance of the separator can be prevented.

[0045] Figure 1 FIG. 1 is a schematic diagram showing that the porosity of the separator 100 for an electrochemical device according to one embodiment of the present disclosure is maintained after lamination. Figure 1 , the separator 100 for an electrochemical device which is one embodiment of the present disclosure will be described in detail.

[0046] According to one embodiment of the present disclosure, the separator 100 for an electrochemical device includes a porous polymer substrate 110. As described above, since the separator 100 for an electrochemical device includes the porous polymer substrate 110, it allows lithium ions to pass while blocking electrical contact between the positive electrode and the negative electrode, and enables a shutdown function to be achieved at an appropriate temperature.

[0047] According to one embodiment of the present disclosure, the porous polymer substrate 110 can be manufactured by using a polyolefin-based resin as a base resin. The polyolefin-based resin can, for example, include polyethylene, polypropylene, polypentene, etc., and can include one or more thereof. Preferably, the porous polymer substrate is composed of polyethylene resin. A porous separator prepared using such a polyolefin-based resin as a base resin, i.e., a separator having a large number of pores, can impart a shutdown function at an appropriate temperature.

[0048] According to one embodiment of the present disclosure, the weight average molecular weight of the polyolefin-based resin may be 500,000 g / mol or more and 1,500,000 g / mol or less. Preferably, the weight average molecular weight of the polyolefin-based resin may be 900,000 g / mol. By adjusting the weight average molecular weight of the polyolefin-based resin within the above range, the compression resistance of the separator can be improved. In addition, when different types of polyolefin-based resins are mixed and used, or when a separator is formed with a multilayer structure made of different types of polyolefin-based resins, the weight average molecular weight of the polyolefin-based resin can be calculated by adding the weight average molecular weight according to the content ratio of the various polyolefin-based resins.

[0049] In the present specification, "weight average molecular weight (Mw)" can be measured by gel permeation chromatography (GPC, PLGPC220, Agilent Technologies), and the measurement conditions can be set as follows.

[0050] -Column: PLOlexis (Polymer Laboratories)

[0051] -Solvent: TCB (trichlorobenzene)

[0052] -Flow rate: 1.0ml / min

[0053] -Sample concentration: 1.0mg / ml

[0054] – Injection volume: 200μl

[0055] - Column temperature: 160℃

[0056] -Detector: Agilent high temperature RI detector

[0057] -Standard: Polystyrene (calibrated with cubic function)

[0058] According to one embodiment of the present disclosure, the porous polymer substrate 110 can be manufactured by the following method (wet method): after kneading a polyolefin-based resin and a plasticizer (diluent) at high temperature to make a single phase, the polymer material and the plasticizer are phase-separated during cooling, and then the plasticizer is extracted to form pores, and then the resulting material is stretched and heat-set. In addition, the porous polymer substrate using a polyolefin-based resin may include a core made of a mixture of polyethylene and polypropylene and a polyethylene surface layer laminated on both surfaces of the core.

[0059] According to one embodiment of the present disclosure, those skilled in the art can easily adjust the average size and maximum size of the pores of the separator 100 to meet the scope of the present disclosure by adjusting the mixing ratio of the plasticizer, the stretching ratio, the heat setting treatment temperature, etc.

[0060] According to one embodiment of the present disclosure, the thickness of the porous polymer substrate may be 1 μm or more and 50 μm or less. The thickness of the porous polymer substrate may be 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, or 8 μm or more. The thickness of the porous polymer substrate may be 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Specifically, the thickness of the porous polymer substrate may be 2 μm or more and 45 μm or less, 3 μm or more and 40 μm or less, 4 μm or more and 35 μm or less, 5 μm or more and 30 μm or less, 6 μm or more and 25 μm or less, 7 μm or more and 20 μm or less, or 8 μm or more and 15 μm or less. By adjusting the thickness of the porous polymer substrate within the above range, the energy density of the battery can be improved.

[0061] According to one embodiment of the present disclosure, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less. The porosity of the porous polymer substrate may be 10% by volume or more, 20% by volume or more, 30% by volume or more, or 40% by volume or more. The porosity of the porous polymer substrate may be 90% by volume or less, 80% by volume or less, 70% by volume or less, or 60% by volume or less. Specifically, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less, 20% by volume or more and 80% by volume or less, 30% by volume or more and 70% by volume or less, or 40% by volume or more and 60% by volume or less. By adjusting the porosity of the porous polymer substrate within the above range, the separator permeability of lithium ions can be controlled.

[0062] According to one embodiment of the present disclosure, the separator 100 for an electrochemical device includes a coating 130 disposed on at least one surface of a porous polymer substrate 110. Specifically, the separator 100 for an electrochemical device includes the coating 130 disposed on one or both surfaces of the porous polymer substrate 110. As described above, since the separator 100 for an electrochemical device includes the coating 130 disposed on at least one surface of the porous polymer substrate 110, the heat resistance of the separator can be improved, the mechanical properties thereof can be improved, and the occurrence of an electrical short circuit of the electrodes due to shrinkage of the separator at high temperatures can be prevented.

[0063] According to one embodiment of the present disclosure, the coating layer 130 includes a first polymer binder 131 in the form of particles, a second polymer binder 133 in the form of particles, and inorganic particles 135. As described above, since the coating layer 130 includes the first polymer binder 131 in the form of particles, the second polymer binder 133 in the form of particles, and the inorganic particles 135, the heat resistance of the separator can be improved, the mechanical properties thereof can be improved, the occurrence of an electrical short circuit of the electrode due to shrinkage of the separator at high temperature can be prevented, and pores can be formed in the coating layer.

[0064] According to one embodiment of the present disclosure, the coating 130 may include a plurality of pores. Specifically, the coating may be a porous coating. More specifically, the coating may be a porous coating including a plurality of pores therein. As described above, since the coating includes a plurality of pores, current can be allowed to flow by allowing lithium ions to pass therethrough while physically blocking the negative electrode and the positive electrode.

[0065] According to one embodiment of the present disclosure, the coating further comprises a region comprising a first polymer binder in the form of a film. Figure 1As schematically shown in FIG. 1 , in the process of preparing an electrochemical device, when pressure and / or heat are applied during lamination with an electrode, the first polymer binder particles used to prepare the coating layer may partially become a film form, that is, become a monolithic structure of a material containing particles changed in this manner. However, at least a portion of the first polymer binder remains in the form of particles.

[0066] According to one embodiment of the present disclosure, inorganic particles 135 may be combined and integrated into the coating by the first polymer binder (i.e., the first polymer binder 131 in particle form and / or the first polymer binder in film form) and the second polymer binder particles 133 to form the coating 130. The pores inside the coating 130 may be generated due to the interstitial volume that is the empty space between the inorganic particles.

[0067] In a method for manufacturing a separator for an electrochemical device by applying a slurry for a coating to at least one surface of a porous polymer substrate, the coating can be formed by a single application. Due to the separation between the inorganic particles on the one hand and the first polymer binder and the second polymer binder on the other hand, the slurry for the coating may have an excess of inorganic particles in the portion close to the porous polymer substrate, and may have an excess of the first polymer binder and the second polymer binder in the portion facing the porous polymer substrate away from the porous polymer substrate, so that the adhesion to the electrode can be improved (increased), and the porosity of the separator can be improved. In this specification, the presence of excess may mean a content of more than 50% by weight in the corresponding portion, and the portion close to the porous polymer substrate and the portion away from the porous polymer substrate may be divided based on an imaginary line accounting for 1 / 2 thickness of the coating.

[0068] In one embodiment, in the separator 100 for an electrochemical device, the amount of inorganic particles in the region of the coating adjacent to the porous polymer substrate is greater than the amount of inorganic particles in the region of the coating opposite to the porous polymer substrate; the amount of the first polymer binder particles and the second polymer binder particles in the region of the coating adjacent to the porous polymer substrate is less than the amount of the first polymer binder particles and the second polymer binder particles in the region of the coating opposite to the porous polymer substrate, wherein if the coating is divided into two halves relative to the thickness of the coating, the region of the coating adjacent to the porous polymer substrate is the half of the coating adjacent to the porous polymer substrate, and the region of the coating opposite to the porous polymer substrate is the half of the coating farther away from the porous polymer substrate.

[0069] According to one embodiment of the present disclosure, the coating layer 130 may be formed to a thickness of 1 μm to 20 μm, 1 μm to 10 μm, 1 μm to 5 μm, or 1.5 μm to 3 μm on either side of the porous polymer substrate 110, but is not particularly limited thereto. Those skilled in the art may adjust the thickness within an appropriate range in terms of heat resistance or electrical resistance.

[0070] In one embodiment of the present disclosure, the thickness of the polymer substrate 110 and / or the coating 130 may be measured by applying a contact type thickness gauge. As a contact type thickness gauge, for example, Mitutoyo's VL-50S-B may be used.

[0071] According to one embodiment of the present disclosure, the glass transition temperature (Tg) of the first polymer binder 131 may be 20°C or higher and 60°C or lower. The glass transition temperature as mentioned herein may be determined by using a differential scanning calorimeter (DSC) or the like. Specific examples of DSC instruments include DSC (DSC823, METTLER TOLEDO), DSC (TAInstrument), and the like. Specifically, the glass transition temperature (Tg) of the first polymer binder may be 22°C or higher and 58°C or lower, 24°C or higher and 56°C or lower, 26°C or higher and 54°C or lower, 28°C or higher and 52°C or lower, 30°C or higher and 50°C or lower, 32°C or higher and 48°C or lower, 34°C or higher and 46°C or lower, 36°C or higher and 44°C or lower, or 38°C or higher and 42°C or lower. Adjusting the glass transition temperature (Tg) of the first polymer binder within the above range makes it possible to adjust the viscosity of the slurry used to prepare the coating layer to improve the convenience of battery manufacturing.

[0072] According to one embodiment of the present disclosure, the average diameter (D 50 ) is not particularly limited, but is preferably in the range of 0.1 μm or more and 1 μm or less to form the coating layer 130 having a uniform thickness and appropriate porosity. Specifically, the average diameter (D 50 ) may be 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, 0.4 μm or more and 0.7 μm or less, or 0.5 μm or more and 0.6 μm or less. The average diameter (D 50 ) is adjusted within the above range, so that the dispersibility in the slurry prepared for coating preparation can be improved (increased) and the thickness of the formed coating can be reduced.

[0073] In this manual, "D 50 "Particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the particle size. The particle size can be measured using a 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 (such as Microtrac S3500) to measure the difference in diffraction patterns according to the particle size when the particles pass through the laser beam, thereby calculating the particle size distribution. 50 The particle size can be measured by calculating the particle size at the point where the particle size distribution in the measuring device becomes 50% of the cumulative distribution of the number of particles according to the particle size. According to one embodiment of the present disclosure, the first polymer binder 131 can be one selected from the following: an acrylic binder; a polyvinylidene-based binder; a hybrid binder comprising an acrylic binder and a polyvinylidene-based binder; and a combination thereof. As described above, the first polymer binder 131 that can be selected from an acrylic binder; a polyvinylidene-based binder; a hybrid binder comprising an acrylic binder and a polyvinylidene-based binder; and a combination thereof is selected, and thus the acrylic binder can be formed into a film during lamination with the electrode to improve (increase) the adhesion to the electrode.

[0074] According to one embodiment of the present disclosure, the hybrid binder is a mixture of an acrylic binder and a polyvinylidene-based binder uniformly mixed, or a hybrid binder including acrylic repeating units and polyvinylidene-based repeating units, and may mean that it is derived from an acrylic binder and a polyvinylidene-based binder.

[0075] According to one embodiment of the present disclosure, the acrylic binder contained in the first polymer binder 131 or forming the first polymer binder 131 may be a (meth) acrylate copolymer, such as a methacrylate copolymer, an acrylonitrile acrylate copolymer, or a styrene acrylate copolymer; a (meth) acrylic resin; or the like. Specifically, it may be one or more selected from the following: a copolymer of styrene and butyl acrylate, a polymer of ethylhexyl acrylate, polyacrylonitrile, acrylonitrile-styrene-butadiene copolymer, and polybutyl acrylate. The acrylic binder contained in the first polymer binder 131 or forming the first polymer binder 131 is selected from the above-mentioned acrylic binders, and thus in the process of lamination with the electrode, the acrylic binder may be formed into a film, thereby improving the adhesion to the electrode.

[0076] According to one embodiment of the present disclosure, the polyvinylidene-based binder contained in the first polymer binder 131 or forming the first polymer binder 131 may be a polyvinylidene fluoride-based binder. As described above, the polyvinylidene-based binder is selected as the polyvinylidene fluoride-based binder, and thus the resistance of the separator may be prevented from increasing or the resistance of the separator may be reduced.

[0077] According to one embodiment of the present disclosure, the hexafluoropropylene (HFP) content of the polyvinylidene-based binder contained in the first polymer binder 131 or forming the first polymer binder 131 may be 10 wt % or more. Specifically, the hexafluoropropylene content of the polyvinylidene-based binder contained in the first polymer binder particles may be 10 wt % or more and 80 wt % or less, 15 wt % or more and 75 wt % or less, 20 wt % or more and 70 wt % or less, 25 wt % or more and 65 wt % or less, 30 wt % or more and 60 wt % or less, 35 wt % or more and 55 wt % or less, or 40 wt % or more and 50 wt % or less. The content of hexafluoropropylene contained in the polyvinylidene-based binder in the first polymer binder particles is adjusted within the above range, and thus the resistance of the separator can be prevented from increasing or the resistance of the separator can be reduced. The content of the HFP monomer can be adjusted by 1 H-NMR and / or 19 Determined by F-NMR.

[0078] According to one embodiment of the present disclosure, the total content of the first polymer binder 131 and the second polymer binder 133 may be 30 parts by weight or less based on 100 parts by weight of the coating 130. The total content of the first polymer binder 131 and the second polymer binder 133 may be more than 0 parts by weight, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, or 11 parts by weight or more based on 100 parts by weight of the coating 130. Based on 100 parts by weight of coating 130, the total content of first polymer binder 131 and second polymer binder 133 can be 28 parts by weight or less, 27 parts by weight or less, 26 parts by weight or less, 25 parts by weight or less, 24 parts by weight or less, 23 parts by weight or less, 22 parts by weight or less, 21 parts by weight or less, 20 parts by weight or less, 19 parts by weight or less, 18 parts by weight or less, or 17 parts by weight or less. Specifically, the total content of the first polymer binder 131 and the second polymer binder 133 may be more than 0 parts by weight and 29 parts by weight or less, 1 part by weight or more and 27 parts by weight or less, 2 parts by weight or more and 25 parts by weight or less, 3 parts by weight or more and 22 parts by weight or less, 4 parts by weight or more and 21 parts by weight or less, 5 parts by weight or more and 20 parts by weight or less, 6 parts by weight or more and 19 parts by weight or less, 7 parts by weight or more and 18 parts by weight or less, 8 parts by weight or more and 17 parts by weight or less, 9 parts by weight or more and 16 parts by weight or less, 10 parts by weight or more and 15 parts by weight or less, 11 parts by weight or more and 14 parts by weight or less, or 12 parts by weight or more and 13 parts by weight or less, based on 100 parts by weight of the coating layer 130. The total content of the first polymer binder 131 and the second polymer binder 133 is adjusted within the above range, and thus the ease of assembly in the process of assembling the electrode can be improved.

[0079] According to one embodiment of the present disclosure, the average diameter (D 50 ) is not particularly limited, but is preferably in the range of 0.1 μm or more and 1 μm or less to form the coating layer 130 having a uniform thickness and appropriate porosity. Specifically, the average diameter (D 50 ) may be 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, 0.4 μm or more and 0.7 μm or less, or 0.5 μm or more and 0.6 μm or less. The average diameter (D 50) is adjusted within the above range, and thus the dispersibility in the slurry prepared for preparing the coating can be improved, and the thickness of the formed coating can be reduced. In this specification, “D 50 "Particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the particle size. The particle size can be measured using a 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 (such as Microtrac S3500) to measure the difference in diffraction patterns according to the particle size when the particles pass through the laser beam, thereby calculating the particle size distribution. 50 The particle diameter can be measured by calculating the particle diameter at a point where the particle diameter distribution in the measuring device becomes 50% of the cumulative distribution of the number of particles according to the particle diameter.

[0080] According to one embodiment of the present disclosure, the second polymer binder 133 is one selected from the following: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt %; a polyolefin-based binder; and a combination thereof. As described above, the second polymer binder 133 is selected to be one selected from the following: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt %; a polyolefin-based binder; and a combination thereof, and thus the porosity of the separator can be maintained. Specifically, referring to Figure 1 , the acrylic binder particles (= the first polymer binder in particle form) become film-formed due to the pressure applied during the lamination process with the electrode, thereby reducing the porosity of the coating layer 130 and interfering with the movement of ions through the pores, so that there is a problem of increasing resistance. However, for the second polymer binder 133 in particle form, a polyvinylidene-based binder or / and a polyolefin-based binder containing a low content of hexafluoropropylene is selected as described above, and thus the second polymer binder particles 133 can withstand the pressure applied during the lamination process during the lamination process with the electrode, thereby maintaining the porosity, and thereby enabling lithium ions to move through the separator, thereby preventing the resistance from increasing.

[0081] According to one embodiment of the present disclosure, the polyvinylidene-based binder in the second polymer binder 133 may include hexafluoropropylene (HFP) in an amount of less than 10 wt % based on the total weight of the polyvinylidene-based binder. The polyvinylidene-based binder in the second polymer binder 133 may include hexafluoropropylene in an amount of 9.9 wt % or less, 9.5 wt % or less, 9.0 wt % or less, 8.5 wt % or less, 8.0 wt % or less, 7.5 wt % or less, 7.0 wt % or less, 6.5 wt % or less, 6.0 wt % or less, or 5.5 wt % or less based on the total weight of the polyvinylidene-based binder. The polyvinylidene-based binder in the second polymer binder 133 may include hexafluoropropylene in an amount of more than 0 wt %, 0.1 wt % or more, 0.5 wt % or more, 1.0 wt % or more, 1.5 wt % or more, 2.0 wt % or more, 2.5 wt % or more, 3.0 wt % or more, 3.5 wt % or more, 4.0 wt % or more, or 4.5 wt % or more, based on the total weight of the polyvinylidene-based binder. Specifically, based on the total weight of the polyvinylidene-based binder, the polyvinylidene-based binder may include hexafluoropropylene in an amount of more than 0 wt % and less than 10 wt %, 0.1 wt % or more and 9.9 wt % or less, 0.5 wt % or more and 9.5 wt % or less, 1.0 wt % or more and 9.0 wt % or less, 1.5 wt % or more and 8.5 wt % or less, 2.0 wt % or more and 8.0 wt % or less, 2.5 wt % or more and 7.5 wt % or less, 3.0 wt % or more and 7.0 wt % or less, 3.5 wt % or more and 6.5 wt % or less, 4.0 wt % or more and 6.0 wt % or less, or 4.5 wt % or more and 5.5 wt % or less. Preferably, the content of hexafluoropropylene in the polyvinylidene-based binder may be 5.0 wt %. The content of hexafluoropropylene contained in the polyvinylidene-based binder is adjusted within the above range, and thus the porosity of the separator can be maintained to improve the resistance of the separator. In the present specification, the degree of substitution of the polyvinylidene-based binder may mean a weight ratio of hexafluoropropylene. The content of the HFP monomer in the polyvinylidene-based binder may be adjusted by 1 H-NMR and / or 19 Determined by F-NMR.

[0082] According to one embodiment of the present disclosure, the polyvinylidene-based binder in the second polymer binder 133 may be a polyvinylidene fluoride (PVdF)-based binder. As described above, the polyvinylidene-based binder is selected as a polyvinylidene fluoride-based binder, and thus the porosity of the separator can be maintained, thereby improving (reducing) the resistance of the separator. In addition, the polyvinylidene-based binder for the second polymer binder particles may be the same or different from the polyvinylidene-based binder contained in the first polymer binder.

[0083] According to an embodiment of the present disclosure, the polyolefin-based binder in the second polymer binder 133 may be polyethylene. As described above, the polyolefin-based binder in the second polymer binder particles 133 is selected as polyethylene, and thus the porosity of the separator can be maintained to improve the resistance of the separator.

[0084] According to one embodiment of the present disclosure, the weight ratio of the first polymer binder 131 and the second polymer binder 133 contained in the coating layer may be 1:9 to 9:1. Specifically, the weight ratio of the first polymer binder 131 and the second polymer binder 133 contained in the coating layer may be 2:8 to 8:2, 3:7 to 7:3, or 4:6 to 6:4. The weight ratio of the first polymer binder 131 and the second polymer binder 133 contained in the coating layer is adjusted within the above range, and thus the resistance of the separator can be prevented from increasing or the resistance of the separator can be reduced, and the ease of assembly in the process of assembling the electrode can be improved.

[0085] According to one embodiment of the present disclosure, when the second polymer binder 133 includes a combination of a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % and a polyolefin-based binder, the weight ratio of the polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % and the polyolefin-based binder may be 1:9 to 9:1. Specifically, when the second polymer binder 133 includes a combination of a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % and a polyolefin-based binder, the weight ratio of the polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % and the polyolefin-based binder may be 2:8 to 8:2, 3:7 to 7:3, or 4:6 to 6:4. The weight ratio of the polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % and the polyolefin-based binder of the second polymer binder 133 is adjusted within the above range, and thus the resistance of the separator can be prevented from increasing or the resistance of the separator can be reduced, and the ease of assembly during the process of assembling the electrode can be improved.

[0086] According to one embodiment of the present disclosure, the inorganic particles 135 that can be used in the coating layer 130 are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present disclosure are not particularly limited as long as they are within the operating voltage range of the applied electrochemical device (e.g., based on Li / Li + Those that do not undergo oxidation and / or reduction reactions within a range of 0 V to 5 V are sufficient.

[0087] According to one embodiment of the present disclosure, the inorganic particles 135 may be included in an amount of 70 parts by weight or more based on 100 parts by weight of the coating 130. Based on 100 parts by weight of the coating 130, the inorganic particles 135 may be included in an amount of 70 parts by weight or more, 71 parts by weight or more, 72 parts by weight or more, 73 parts by weight or more, 74 parts by weight or more, 75 parts by weight or more, 76 parts by weight or more, 77 parts by weight or more, 78 parts by weight or more, 79 parts by weight or more, 80 parts by weight or more, 81 parts by weight or more, 82 parts by weight or more, 83 parts by weight or more, 84 parts by weight or more, or 85 parts by weight or more. Based on 100 parts by weight of the coating layer 130, the inorganic particles 135 may be included in an amount of less than 100 parts by weight, 99 parts by weight or less, 98 parts by weight or less, 97 parts by weight or less, 96 parts by weight or less, 95 parts by weight or less, 94 parts by weight or less, 93 parts by weight or less, 92 parts by weight or less, 91 parts by weight or less, 90 parts by weight or less, 89 parts by weight or less, or 88 parts by weight or less. Specifically, the inorganic particles 135 may be contained in an amount of 72 parts by weight or more and less than 100 parts by weight, 74 parts by weight or more and 99 parts by weight or less, 76 parts by weight or more and 98 parts by weight or less, 78 parts by weight or more and 97 parts by weight or less, 79 parts by weight or more and 96 parts by weight or less, 80 parts by weight or more and 95 parts by weight or less, 81 parts by weight or more and 94 parts by weight or less, 82 parts by weight or more and 93 parts by weight or less, 83 parts by weight or more and 92 parts by weight or less, 84 parts by weight or more and 91 parts by weight or less, 85 parts by weight or more and 90 parts by weight or less, 86 parts by weight or more and 89 parts by weight or less, or 87 parts by weight or more and 88 parts by weight or less, based on 100 parts by weight of the coating layer 130. Adjusting the content of the inorganic particles 135 within the above range can improve the heat resistance of the separator.

[0088] According to one embodiment of the present disclosure, when inorganic particles with a high dielectric constant are used, the inorganic particles help to increase the dissociation of electrolyte salts (e.g., lithium salts) in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution. For the above reasons, the inorganic particles can be inorganic particles with a dielectric constant greater than or equal to 5, inorganic particles with lithium ion transport capability, or a mixture thereof.

[0089] According to one embodiment of the present disclosure, non-limiting examples of the inorganic particles 135 may 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), hafnium dioxide (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), etc., and may include one or two or more of them.

[0090] According to one embodiment of the present disclosure, the total content of the inorganic particles 135 in the coating 130 may be 70 parts by weight or more based on 100 parts by weight of the coating 130. The total content of the inorganic particles 135 in the coating 130 may be 70 parts by weight or more, 71 parts by weight or more, 72 parts by weight or more, 73 parts by weight or more, 74 parts by weight or more, 75 parts by weight or more, 76 parts by weight or more, 77 parts by weight or more, 78 parts by weight or more, 79 parts by weight or more, 80 parts by weight or more, 81 parts by weight or more, 82 parts by weight or more, 83 parts by weight or more, 84 parts by weight or more, or 85 parts by weight or more based on 100 parts by weight of the coating 130. Based on 100 parts by weight of the coating 130, the total content of the inorganic particles 135 in the coating 130 can be less than 100 parts by weight, 99 parts by weight or less, 98 parts by weight or less, 97 parts by weight or less, 96 parts by weight or less, 95 parts by weight or less, 94 parts by weight or less, 93 parts by weight or less, 92 parts by weight or less, 91 parts by weight or less, 90 parts by weight or less, 89 parts by weight or less, or 88 parts by weight or less. Specifically, based on 100 parts by weight of the coating layer 130, the total content of the inorganic particles 135 in the coating layer 130 may be 72 parts by weight or more and less than 100 parts by weight, 74 parts by weight or more and 99 parts by weight or less, 76 parts by weight or more and 98 parts by weight or less, 78 parts by weight or more and 97 parts by weight or less, 79 parts by weight or more and 96 parts by weight or less, 80 parts by weight or more and 95 parts by weight or less, 81 parts by weight or more and 94 parts by weight or less, 82 parts by weight or more and 93 parts by weight or less, 83 parts by weight or more and 92 parts by weight or less, 84 parts by weight or more and 91 parts by weight or less, 85 parts by weight or more and 90 parts by weight or less, 86 parts by weight or more and 89 parts by weight or less, or 87 parts by weight or more and 88 parts by weight or less. The total content of the inorganic particles 135 is adjusted within the above range, and thus the ease of assembly in the process of assembling the electrode can be improved.

[0091] According to one embodiment of the present disclosure, the average diameter (D 50 ) is not particularly limited, but is preferably in the range of 0.3 μm or more and 1 μm or less to form the coating layer 130 having a uniform thickness and appropriate porosity. The average diameter (D 50 ) may be 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more. The average diameter (D 50 ) may be 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, or 0.6 μm or less. Specifically, the average diameter (D 50) may be 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, 0.4 μm or more and 0.7 μm or less, or 0.5 μm or more and 0.6 μm or less. Preferably, the average diameter (D 50 Specifically, when the average diameter is less than 0.3 μm, the dispersibility of the inorganic particles in the slurry prepared for preparing the coating layer may be reduced, and when the average diameter exceeds 1 μm, the thickness of the coating layer to be formed may be increased.

[0092] In this manual, "D 50 "Particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the particle size. The particle size can be measured using a 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 (such as Microtrac S3500) to measure the difference in diffraction patterns according to the particle size when the particles pass through the laser beam, thereby calculating the particle size distribution. 50 The particle diameter can be measured by calculating the particle diameter at a point where the particle diameter distribution in the measuring device becomes 50% of the cumulative distribution of the number of particles according to the particle diameter.

[0093] According to one embodiment of the present disclosure, the porosity of the coating 130 may be 30% by volume or more. The porosity of the coating 130 may be 30% by volume or more, 32% by volume or more, 33% by volume or more, 34% by volume or more, 36% by volume or more, 38% by volume or more, 40% by volume or more, 42% by volume or more, 44% by volume or more, 46% by volume or more, or 48% by volume or more. The porosity of the coating 130 may be 70% by volume or less, 68% by volume or less, 66% by volume or less, 64% by volume or less, 62% by volume or less, 60% by volume or less, 58% by volume or less, 56% by volume or less, 54% by volume or less, or 52% by volume or less. Specifically, the porosity of the coating 130 may be 30% by volume or more and 70% by volume or less, 32% by volume or more and 68% by volume or less, 34% by volume or more and 66% by volume or less, 36% by volume or more and 64% by volume or less, 38% by volume or more and 62% by volume or less, 40% by volume or more and 60% by volume or less, 42% by volume or more and 58% by volume or less, 44% by volume or more and 56% by volume or less, 46% by volume or more and 54% by volume or less, or 48% by volume or more and 52% by volume or less. The porosity of the coating 130 is adjusted within the above range so that the movement of ions in the separator can be maintained and the increase in the resistance of the separator can be prevented. Specifically, if the porosity is 70% by volume or less, it is possible to ensure that the dynamic characteristics of the pressing process that can be combined with the electrode can be withstood, and since the surface opening rate does not become too high, it is also suitable for ensuring adhesion. Meanwhile, when the porosity is 30 volume % or more, it is advantageous in terms of ion permeability.

[0094] In the present specification, "porosity" means the ratio of the volume occupied by pores to the total volume, uses volume % as its unit, and can be used interchangeably with terms such as void ratio and porosity.

[0095] In the present specification, the porosity may correspond to a value obtained by subtracting a volume converted by the weight and density of each component of the porous polymer substrate 110 and / or the coating 130 from a volume calculated by the thickness, width, and length of the porous polymer substrate 110 and / or the coating 130 .

[0096] In the present specification, the porosity and pore size of the porous polymer substrate 110 and / or the coating layer 130 may be measured using a scanning electron microscope (SEM) image, a mercury porosimeter, or a capillary flow porosimeter, or using a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini) by a nitrogen adsorption flow method using a BET 6-point method. At this time, the use of a capillary flow porosimeter may be advantageous.

[0097] According to one embodiment of the present disclosure, the polyvinylidene-based binder having a hexafluoropropylene content of less than 10% by weight may be an aqueous binder. Specifically, the polyvinylidene-based binder having a hexafluoropropylene content of less than 10% by weight is selected as an aqueous binder, and thus the increase in the resistance of the separator can be prevented. In this specification, a "water-based binder" is a binder soluble in water, and may mean a binder having a solubility index similar to that of water.

[0098] According to one embodiment of the present disclosure, the dry adhesion of the coating can be 30gf / 25mm or larger. The dry adhesion of the coating can be 35gf / 25mm or larger, 40gf / 25mm or larger, 45gf / 25mm or larger, 50gf / 25mm or larger, 55gf / 25mm or larger, or 60gf / 25mm or larger. The dry adhesion of the coating can be 100gf / 25mm or smaller, 95gf / 25mm or smaller, 90gf / 25mm or smaller, 85gf / 25mm or smaller, 80gf / 25mm or smaller, 75gf / 25mm or smaller, or 70gf / 25mm or smaller. Specifically, the dry adhesive force of coating can be 30gf / 25mm or larger and 100gf / 25mm or smaller, 35gf / 25mm or larger and 95gf / 25mm or smaller, 40gf / 25mm or larger and 90gf / 25mm or smaller, 45gf / 25mm or larger and 85gf / 25mm or smaller, 50gf / 25mm or larger and 80gf / 25mm or smaller, 55gf / 25mm or larger and 75gf / 25mm or smaller, or 60gf / 25mm or larger and 70gf / 25mm or smaller. As mentioned above, the dry adhesive force of coating is adjusted, and therefore the ease of assembly in the process of assembling electrode can be improved.

[0099] In the present specification, the dry adhesion of the coating may refer to the adhesion obtained by measuring the strength obtained by cutting the separator into 70 mm (length) × 25 mm (width) and laminating the prepared electrode and separator using a press at 60°C, 6.5 MPa and 1 second to manufacture a sample, attaching and fixing the prepared sample to a glass plate using a double-sided tape, and setting the sample so that the electrode faces the glass plate, and then peeling off the separator part of the sample at an angle of 180° at a rate of 150 mm / min at 25°C.

[0100] According to an embodiment of the present disclosure, an adhesive polymer binder may be provided on the coating 130. Specifically, an adhesive polymer binder may be provided on the opposite surface of the coating opposite to the surface of the adjacent porous polymer substrate. More specifically, the opposite surface of the coating is covered with the adhesive polymer binder. As described above, by providing an adhesive polymer binder on the coating 130, the dry adhesion and wet adhesion of the electrode are improved, respectively.

[0101] According to an embodiment of the present disclosure, the adhesive polymer binder may be a particle type, a solution type, and a combination thereof. In the present specification, "particle type" may define an adhesive polymer binder that maintains a particle phase because it will not be dissolved by the electrolyte inserted in the battery cell. In the present specification, "solution type" may define an adhesive polymer binder that does not maintain a particle phase because it is dissolved by the electrolyte inserted in the battery cell. By selecting the type of adhesive polymer binder mentioned above, the dry adhesion and wet adhesion of the electrode are improved respectively.

[0102] According to an embodiment of the present disclosure, an adhesive polymer binder is provided on a portion of the coating layer 130. As described above, by providing the adhesive polymer binder on a portion of the coating layer 130, dry adhesion and wet adhesion to the electrode are improved, respectively.

[0103] According to an embodiment of the present disclosure, based on the total area of ​​the coating, the adhesive polymer binder is provided as an area greater than 0% and less than 100%. Specifically, based on the total area of ​​the coating, the adhesive polymer binder is provided as an area of ​​1% or more and 99% or less, 5% or more and 95% or less, 10% or more and 90% or less, 15% or more and 85% or less, 20% or more and 80% or less, 25% or more and 75% or less, 30% or more and 70% or less, 35% or more and 65% or less, 40% or more and 60% or less, or 45% or more and 55% or less. The area provided by the adhesive polymer binder on the coating is adjusted within the above range, and the dry adhesion and wet adhesion of the electrode are improved respectively.

[0104] According to an embodiment of the present disclosure, the adhesive polymer binder may be the same as the first polymer binder and the second polymer binder, or may be different from the first polymer binder and the second polymer binder. Selecting the type of the adhesive polymer binder as described above can adjust the adhesion between the coating and the adhesive polymer binder, can prevent the adhesive polymer binder from being dissolved by the electrolyte, and can minimize the resistance of the battery cell.

[0105] According to an embodiment of the present disclosure, the adhesive polymer binder can be provided on a portion of the coating layer by spraying, rod coating, spin coating, or dip coating. By selecting the method of providing the adhesive polymer binder as described above, the adhesive polymer binder is easily provided on the coating layer.

[0106] One embodiment of the present disclosure provides a method for manufacturing a separator for an electrochemical device, the method comprising the following steps: mixing a slurry for a coating 130, i.e., a slurry for preparing the coating 130 (S10), the slurry comprising a first polymer binder 131 in particle form, a second polymer binder 133 in particle form, and inorganic particles 135; applying the slurry for the coating to at least one surface of a porous polymer substrate 110 (S30); and drying the slurry for the coating to form the coating 110 (S50), wherein the second polymer binder 133 is selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt %; a polyolefin-based binder; and combinations thereof.

[0107] The method for manufacturing a separator for an electrochemical device according to one embodiment of the present disclosure can easily prevent an increase in the resistance of the separator and can enable polymer binder particles to support pressure applied during lamination with an electrode, thereby preventing a decrease in the porosity of the separator.

[0108] Figure 2 FIG. 1 is a flow chart of a method for manufacturing a separator 100 for an electrochemical device according to an embodiment of the present disclosure. Figure 2 , a method for manufacturing a separator 100 for an electrochemical device according to one embodiment of the present disclosure will be described in detail. In the description of the method for manufacturing a separator 100 for an electrochemical device according to one embodiment of the present disclosure, contents overlapping with the description of the separator for an electrochemical device will be omitted.

[0109] According to one embodiment of the present disclosure, the method for manufacturing a separator 100 for an electrochemical device includes a step (S10) of mixing a slurry for coating, the slurry for coating including first polymer binder particles 131 (i.e., a first polymer binder in the form of particles), second polymer binder particles 133 (i.e., a second polymer binder in the form of particles), and inorganic particles 135. As described above, the method includes a step (S10) of mixing a slurry for coating including first polymer binder particles 131, second polymer binder particles 133, and inorganic particles 135, and thus a coating can be easily formed on the separator.

[0110] According to an embodiment of the present disclosure, the polymer binder resin, i.e., the first polymer binder particles 131 and the second polymer binder particles 133, can be dispersed in a suitable dispersion medium to prepare a polymer emulsion, thereby forming a slurry for coating. As a dispersion medium, preferably a dispersion medium having a solubility index similar to the solubility index of the binder polymer to be used and having a low boiling point. This is to promote uniform mixing and subsequent removal of the dispersion medium. The non-limiting examples of available dispersion medium include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof. Preferably, the solvent can be water. In this specification, the dispersion medium is the dispersion medium used in the process of preparing the slurry, and can mean a solvent.

[0111] According to one embodiment of the present disclosure, the inorganic particles 135 may be added to the polymer emulsion and dispersed in the polymer emulsion. The content ratio of the inorganic particles to the polymer binder particles is as described above, and is appropriately adjusted in consideration of the thickness, pore size, and porosity of the coating layer according to one embodiment of the present disclosure that is finally manufactured.

[0112] According to one embodiment of the present disclosure, the slurry for coating may be prepared by dispersing the first polymer binder particles 131 , the second polymer binder particles 133 , and the inorganic particles 135 in water as a dispersion medium (solvent).

[0113] The slurry for coating may include first polymer binder particles 131 , second polymer binder particles 133 , inorganic particles 135 , and a dispersion medium.

[0114] The mixing of the slurry for coating may be performed for 1 hour or more and 3 hours or less.

[0115] According to one embodiment of the present disclosure, the solid content of the slurry for coating can be 10 wt % or more and 50 wt % or less based on 100 wt % of the slurry. Specifically, the solid content of the slurry for coating can be 15 wt % or more and 40 wt % or less, 20 wt % or more and 35 wt % or less, or 25 wt % or more and 30 wt % or less. The solid content of the slurry for coating is adjusted within the above range, and thus the processability of the coating manufacturing process can be improved.

[0116] According to one embodiment of the present disclosure, the method for manufacturing a separator 100 for an electrochemical device includes a step (S30) of applying a slurry for coating to at least one surface of a porous polymer substrate 100. As described above, the step of applying the slurry for coating to at least one surface of a porous polymer substrate 110 is included, and thus the coating 130 can be formed with one application. Due to the separation between the inorganic particles and the polymer binder particles, the slurry for coating has an excess of inorganic particles 135 in a portion close to the porous polymer substrate 110, and has an excess of polymer binder particles 131 and 133 in a portion opposite to the porous polymer substrate 110 away from the porous polymer substrate 110, so that the adhesion to the electrode can be improved, and the porosity of the separator can be improved. In this specification, the presence of excess may mean that the content in the corresponding portion exceeds 50% by weight, and the portion close to the porous polymer substrate 110 and the portion away from the porous polymer substrate 110 can be divided based on an imaginary line occupying 1 / 2 thickness of the coating.

[0117] According to one embodiment of the present disclosure, the method of applying the slurry for coating to the surface of the porous polymer substrate 110 is not particularly limited to any one method, and conventional methods known in the art can be used. For example, various methods such as dip coating, die coating, roller coating, comma coating, or a combination thereof can be used.

[0118] According to one embodiment of the present disclosure, the method for manufacturing the separator 100 for an electrochemical device includes a step (S50) of forming the coating layer 130 by drying the slurry for coating. As described above, the step (S50) of forming the coating layer 130 by drying the slurry for coating is included, and thus damage to the coating layer can be minimized, and the solvent contained in the slurry can be easily removed.

[0119] According to one embodiment of the present disclosure, during the drying process, time conditions are appropriately set to minimize the occurrence of surface defects of the coating 130. For drying, a drying auxiliary device such as a drying oven or hot air may be used within an appropriate range.

[0120] According to one embodiment of the present disclosure, the temperature of the step of drying may be 25°C or higher and 75°C or lower. The temperature of the step of drying may be 30°C or higher, 35°C or higher, 40°C or higher, or 45°C or higher. The temperature of the step of drying may be 70°C or lower, 65°C or lower, 60°C or lower, or 55°C or lower. Specifically, the temperature of the step of drying may be 30°C or higher and 70°C or lower, 35°C or higher and 65°C or lower, 40°C or higher and 60°C or lower, or 45°C or higher and 55°C or lower. The temperature of the step of drying may be adjusted within the above range, and thus the denaturation of the porous polymer substrate may be prevented, and the dispersion medium may be effectively removed.

[0121] According to one embodiment of the present disclosure, the second polymer binder particles 133 are selected from one of the following: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt %; a polyolefin-based binder; and a combination thereof. As described above, the second polymer binder particles 133 are selected from one of the following: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt %; a polyolefin-based binder; and a combination thereof, and thus the porosity of the separator can be maintained. Specifically, referring to Figure 1 , during the lamination process with the electrode, the acrylic binder particles become a film form, thereby reducing the porosity of the coating and interfering with the movement of ions through the pores, so that there is a problem of increasing resistance. However, for the second polymer binder particles 133, a polyvinylidene-based binder or / and a polyolefin-based binder containing a low content of hexafluoropropylene is selected as described above, and thus the second polymer binder particles 133 can support the pressure applied during the lamination process during the lamination process with the electrode, thereby maintaining the porosity, and thereby enabling ions to move through the separator, thereby preventing the resistance from increasing.

[0122] According to one embodiment of the present disclosure, the step of mixing can be for mixing for 1 hour or longer and 3 hours or shorter. The step of mixing can be for mixing for 1.5 hours or longer. The step of mixing can be for mixing for 2.5 hours or shorter. Preferably, the step of mixing can be for mixing for 1.5 hours or longer and 2.5 hours or shorter or about 2 hours. As described above, the time of adjusting the mixing slurry, and therefore the dispersibility of the inorganic particles 135 contained in the slurry for coating can be improved, and the uniformity of the first polymer binder particles 131, the second polymer binder particles 133 and the inorganic particles 135 in the slurry for coating can be improved.

[0123] According to one embodiment of the present disclosure, the first polymer binder particles 131 used in the method can be one selected from the following: acrylic binder particles; polyvinylidene-based binder particles; hybrid binder particles containing acrylic binder and polyvinylidene-based binder; and combinations thereof. As described above, the first polymer binder particles 131 are selected from the following: acrylic binder particles; polyvinylidene-based binder particles; hybrid binder particles containing acrylic binder and polyvinylidene-based binder; and combinations thereof, and thus the acrylic binder can be formed into a film during lamination with the electrode, thereby improving adhesion to the electrode.

[0124] According to one embodiment of the present disclosure, the difference between the temperature in the step (S50) of drying and the glass transition temperature of the first polymer binder particles may be 20°C or less. The difference between the temperature in the step (S50) of drying and the glass transition temperature of the first polymer binder particles may be greater than 0°C, 1°C or more, 2°C or more, 3°C or more, 4°C or more, 5°C or more, 6°C or more, 7°C or more, 8°C or more, or 9°C or more. The difference between the temperature in the step (S50) of drying and the glass transition temperature of the first polymer binder particles may be 20°C or less, 19°C or less, 18°C ​​or less, 17°C or less, 16°C or less, 15°C or less, 14°C or less, 13°C or less, 12°C or less, or 11°C or less. Specifically, the difference between the temperature in the step of performing drying and the glass transition temperature of the first polymer binder particles may be greater than 0° C. and 20° C. or less, 1° C. or more and 19° C. or less, 2° C. or more and 18° C. or less, 3° C. or more and 17° C. or less, 4° C. or more and 16° C. or less, 5° C. or more and 15° C. or less, 6° C. or more and 14° C. or less, 7° C. or more and 13° C. or less, 8° C. or more and 12° C. or less, or 9° C. or more and 11° C. or less. The difference between the temperature in the step of performing drying and the glass transition temperature of the first polymer binder particles is adjusted within the above range, and thus the first polymer binder particles can be prevented from being melted and disposed on a portion adjacent to the porous polymer substrate.

[0125] According to one embodiment of the present disclosure, the separator 100 is manufactured into an electrochemical device by a lamination process, in which the separator 100 is interposed between the negative electrode and the positive electrode and combined by applying heat and / or pressure. In one embodiment of the present disclosure, the lamination process can be performed by a rolling device including a pair of pressure rollers. That is, interlayer bonding can be achieved by sequentially stacking the negative electrode, the separator, and the positive electrode and placing them between the pressure rollers. At this time, the lamination process can be performed by a hot pressing method.

[0126] One embodiment of the present disclosure provides an electrochemical device 1000 including: a positive electrode 300 ; a negative electrode 500 ; and a separator 100 interposed between the positive electrode 300 and the negative electrode 500 .

[0127] The electrochemical device 1000 according to one embodiment of the present disclosure may improve energy efficiency by reducing the resistance of the separator.

[0128] Figure 3 FIG. 1 is a schematic diagram of an electrochemical device 1000 according to one embodiment of the present disclosure. Figure 3 , an electrochemical device 1000 according to one embodiment of the present disclosure will be described in detail.

[0129] In one embodiment of the present disclosure, an electrochemical device is a device that converts chemical energy into electrical energy by an electrochemical reaction, and is a concept covering primary batteries and secondary batteries. In this specification, a secondary battery can be charged and discharged, and means a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. A lithium secondary battery is a battery using lithium ions as an ion conductor, and examples thereof may include a non-aqueous electrolyte secondary battery containing a liquid electrolyte, an all-solid-state battery containing a solid electrolyte, a lithium polymer battery containing a gel polymer electrolyte, a lithium metal battery in which lithium metal is used as a negative electrode, etc., but are not limited thereto.

[0130] According to one embodiment of the present disclosure, the positive electrode includes a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector containing a positive electrode active material, a conductive material and a binder resin. The positive electrode active material may include: a layered compound, such as a lithium manganese oxide composite (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium manganese oxide, such as a compound of formula Li 1+x Mn 2-x O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3 and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5 and Cu2V2O7; 1-x M x Ni-site lithium nickel oxide represented by O2, wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3; 1-x M xA lithium manganese oxide composite represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4, in which a part of Li in the formula is replaced by an alkaline earth metal ion; a disulfide compound; Fe2(MoO4)3; or a mixture of two or more of them.

[0131] According to an embodiment of the present disclosure, the negative electrode includes a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode may include, as the negative electrode active material, one selected from the following: a lithium metal oxide; carbon, such as non-graphitizable carbon and graphite-based carbon; a metal oxide composite, such as Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1) and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2 and Group 3 of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; a lithium alloy; a silicon-based alloy; a tin-based alloy; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5; a conductive polymer, such as polyacetylene; a Li-Co-Ni-based material; and titanium oxide; or a mixture of two or more of them.

[0132] According to an embodiment of the present disclosure, the conductive material may be, for example, any one selected from the following: graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whisker, conductive metal oxide, activated carbon and polyphenylene derivative, or a mixture of two or more of such conductive materials. More specifically, it may be one selected from the following: natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate and titanium oxide, or a mixture of two or more of such conductive materials.

[0133] According to an embodiment of the present disclosure, the current collector is not particularly limited as long as it does not cause a chemical change in the relevant battery and has high conductivity. For example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. on its surface may be used.

[0134] According to an embodiment of the present disclosure, a polymer commonly used in electrodes in the art can be used as a binder resin. Non-limiting examples of such binder resins can include poly (vinylidene fluoride-co-hexafluoropropylene), polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, etc., but are not limited thereto.

[0135] According to one embodiment of the present disclosure, the positive electrode slurry for preparing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound, specifically, N-methylpyrrolidone (ADC-01, LG Chem).

[0136] According to one embodiment of the present disclosure, based on 100 parts by weight of the positive electrode slurry, the dispersant may be included in the positive electrode slurry in an amount of more than 0 parts by weight and 0.5 parts by weight or less. Specifically, based on 100 parts by weight of the positive electrode slurry, the dispersant may be included in the positive electrode slurry in an amount of more than 0.05 parts by weight and 0.4 parts by weight or less.

[0137] According to one embodiment of the present disclosure, the negative electrode slurry for preparing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinyl pyrrolidone (Junsei, Japan).

[0138] According to one embodiment of the present disclosure, the dispersant may be included in the negative electrode slurry in an amount of more than 0 parts by weight and 0.5 parts by weight or less based on 100 parts by weight of the negative electrode slurry. Specifically, the dispersant may be included in the negative electrode slurry in an amount of more than 0.05 parts by weight and 0.4 parts by weight or less based on 100 parts by weight of the negative electrode slurry.

[0139] According to one embodiment of the present disclosure, a battery may be manufactured by loading the electrochemical device prepared as described above into an appropriate housing and injecting an electrolyte.

[0140] According to one embodiment of the present disclosure, the electrolyte is + B - A salt of the structure + Including alkali metal cations such as Li + 、Na + and K +or a combination thereof, and B - Including anions such as PF6 - 、BF4 - , Cl - Br - ,I - 、ClO4 - 、AsF6 - 、CH3CO2 - CF3SO3 - 、N(CF3SO2)2 - and C(CF2SO2)3 - Salts of ions consisting of or combinations thereof may include those that dissolve or dissociate in an organic solvent consisting of 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 (γ-butyrolactone), or a mixture thereof, but are not limited thereto.

[0141] One embodiment of the present disclosure provides a battery module including a battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source, wherein the battery includes an electrochemical device. Specific examples of the device may include: an electric tool driven by an electric motor by receiving electric power; 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; a power storage system; etc., but are not limited thereto.

[0142] Embodiments of the invention

[0143] Hereinafter, embodiments will be described in detail to explain the present disclosure in detail. However, embodiments according to the present disclosure may be modified in various forms, and the scope of the present disclosure should not be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more fully explain the present disclosure to those skilled in the art.

[0144] <Example 1>

[0145] A polyethylene resin (weight average molecular weight of 900,000) was extruded, and a porous polymer substrate (total thickness of about 9 μm and porosity of 40% by volume) was manufactured by a wet process.

[0146] A mixture of a copolymer of styrene and butyl acrylate (styrene-butyl acrylate, glass transition temperature of 40°C) as the first polymer binder particles and a second polymer binder particles, the copolymer of styrene and butyl acrylate being an acrylic binder having a particle size of 500nm, the mixture being obtained by mixing polyethylene having a particle size of 500nm with a copolymer of PVdF and HFP having a substitution degree (weight ratio of HFP contained in a polymer based on PVdF) of 5% by weight (which is a binder based on polyvinylidene having a particle size of 500nm) in a weight ratio of 1:1, and the first polymer binder particles, the second polymer binder particles and inorganic particles (Al2O3, particle size of 500nm) were put into water, and mixed and dispersed for 2 hours to prepare a slurry for coating (solid content of 30%). The weight ratio of the first polymer binder particles to the second polymer binder particles was 1:1, and the weight ratio of the polymer binder particles to the inorganic particles was 25:75.

[0147] The dispersion was applied to both surfaces of the porous polymer substrate by a bar coating method using a doctor blade, and dried with wind at 50° C. using a heat gun.

[0148] <Example 2>

[0149] A separator was manufactured in the same manner as in Example 1 above, except that only a PVDF-based binder including 9 wt % of HFP was used as the second polymer binder particles in Example 1 above.

[0150] <Example 3>

[0151] A separator was manufactured in the same manner as in Example 1 above, except that only polyethylene was used as the second polymer binder particles in Example 1 above.

[0152] <Example 4>

[0153] In order to manufacture a separator, styrene-butyl acrylate (glass transition temperature of 40°C and particle size of 500nm) (which is an acrylic binder) is applied as an adhesive polymer binder on the coating of the separator manufactured in Example 1 by a spraying method to provide 50% of the area of ​​the adhesive polymer binder based on the total area of ​​the coating, and the separator is manufactured.

[0154] <Comparative Example 1>

[0155] A separator was manufactured in the same manner as in Example 1 above, except that the second polymer binder particles were not included in Example 1 above.

[0156] <Comparative Example 2>

[0157] A separator was manufactured in the same manner as in Example 1 above, except that a polymer of 2-ethylhexyl acrylate (2-EHA), which is an acrylic binder, was used as the second polymer binder particles in Example 1 above.

[0158] <Manufacturing of Electrochemical Device>

[0159] 1) Manufacturing of positive electrode

[0160] The positive electrode active material (LiNi 0.8 Mn 0.1 Co 0.1 O2), a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chem) and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a positive electrode active material layer having a concentration of 50 wt % of the remaining components except water. Next, the slurry was applied to the surface of an aluminum film (thickness of 10 μm) and dried to prepare a positive electrode with a positive electrode active material layer (thickness of 120 μm).

[0161] 2) Manufacturing of negative electrode

[0162] Graphite (a blend of natural graphite and artificial graphite), a conductive material (carbon black), a dispersant (polyvinyl pyrrolidone, Junsei, Japan) and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water at a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a negative electrode active material layer having a concentration of 50 wt % of the remaining components except water. Next, the slurry was applied to the surface of a copper thin film (thickness of 10 μm) and dried to prepare a negative electrode having a negative electrode active material layer (thickness of 120 μm).

[0163] 3) Lamination process

[0164] The electrode assembly was obtained by interposing the separators of the examples and comparative examples between the prepared negative electrode and positive electrode, stacking them, and performing a lamination process The lamination process was performed by using a hot press under the conditions of 70° C. and 5.2 MPa for 10 seconds.

[0165] <Experimental Example 1: Measurement of Porosity of Coating>

[0166] The porosity is calculated by the following [Equation 1] and [Equation 2].

[0167] [Equation 1]

[0168] Porosity (volume %) = {1-(apparent density / true density)} × 100

[0169] [Equation 2]

[0170] Apparent density (g / cm 3 ) = {weight of coating [g] / (thickness of coating [cm]×area of ​​coating [cm 2 ])}

[0171] Three samples with a size of 5 cm in the MD / TD direction were obtained from the coating of each embodiment and comparative example. For the thickness of the coating, an average value was used after measuring 5 points for each sample, and the weight of each sample was measured using a balance. The average value of the three samples was calculated and introduced into the above equations 1 and 2 to calculate the porosity. At the same time, the true density of each sample was applied based on theoretically determined values ​​such as the molecular weight of various applied components. In this regard, the true density defines that the value is calculated by volume and mass. The volume is measured under the condition that the coating does not include closed pores.

[0172] <Experimental Example 2: Measurement of Separator Resistance>

[0173] Each separator substrate is interposed between stainless steels, an electrolyte is injected to make a coin cell, and the electrical resistance (ER) is measured by electrochemical impedance spectroscopy (EIS). At this time, the frequency is in the range of 10,000 Hz to 100,000 Hz. The electrolyte is obtained by mixing LiPF6 at a concentration of 1 M in a non-aqueous solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a ratio of 3:7.

[0174] [Table 1]

[0175] Porosity of coating (volume %) Resistance of separator (Ω) Example 1 38％ 0.65 Example 2 35％ 0.73 Example 3 36％ 0.71 Example 4 38％ 0.67 Comparative Example 1 33％ 0.79 Comparative Example 2 30％ 0.85

[0176] Referring to Table 1, it was determined that in all of Examples 1 to 3 including a polyvinylidene-based binder containing a low content of hexafluoropropylene or a polyolefin-based binder, the resistance of the separator was achieved to be 0.73Ω or less, and the porosity of the coating was achieved to be 35 volume % or more.

[0177] In contrast, it was determined that in Comparative Example 1 not containing the second polymer binder particles, the porosity decreased and the resistance of the separator increased. In addition, it was determined that in Comparative Example 2 using only an acrylic binder as the second polymer binder particles, the porosity also decreased and the resistance of the separator increased.

[0178] Finally, according to one embodiment of the present disclosure, by including a polyvinylidene-based binder or a polyolefin-based binder containing a low content of hexafluoropropylene in the coating layer, the resistance of the separator can be prevented from increasing or can be reduced, and the porosity of the coating layer can be improved.

[0179] [Explanation of Reference Numerals]

[0180] 100: Separators for electrochemical devices

[0181] 110: Porous polymer substrate

[0182] 130: Coating

[0183] 131: First polymer binder particles

[0184] 133: Second polymer binder particles

[0185] 135: Inorganic particles

[0186] 300: Positive

[0187] 500: Negative

[0188] 1000: Electrochemical Devices

Claims

1. A separator for an electrochemical device, comprising: a porous polymer substrate; and a coating disposed on at least one surface of the porous polymer substrate, wherein the coating comprises a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles, and The second polymer binder is selected from: a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of less than 10 wt % relative to the total weight of the polyvinylidene-based binder; a polyolefin-based binder; and combinations thereof.

2. The separator for an electrochemical device according to claim 1, wherein - the amount of the inorganic particles in the region of the coating adjacent to the porous polymer substrate is greater than the amount of the inorganic particles in the region of the coating opposite to the porous polymer substrate; - the amount of the first polymer binder and the second polymer binder in the area of ​​the coating adjacent to the porous polymer substrate is less than the amount of the first polymer binder and the second polymer binder in the area of ​​the coating opposite to the porous polymer substrate; Wherein if the coating is divided into two halves relative to the thickness of the coating, the area of ​​the coating adjacent to the porous polymer substrate is the half of the coating adjacent to the porous polymer substrate, and the area of ​​the coating opposite to the porous polymer substrate is the half of the coating farther away from the porous polymer substrate. 3 . The separator for an electrochemical device according to claim 1 , wherein the coating layer further includes a region including the first polymer binder in the form of a film. 4 . The separator for an electrochemical device according to claim 1 , wherein the polyvinylidene-based binder is a polyvinylidene fluoride-based binder. 5 . The separator for an electrochemical device according to claim 1 , wherein the polyolefin-based binder is polyethylene. 6 . The separator for an electrochemical device according to claim 1 , wherein the first polymer binder is selected from the group consisting of: an acrylic binder; a polyvinylidene-based binder; a hybrid binder comprising an acrylic binder and a polyvinylidene-based binder; and combinations thereof. 7 . The separator for an electrochemical device according to claim 6 , wherein the polyvinylidene-based binder is a polyvinylidene fluoride-based binder. 8 . The separator for an electrochemical device according to claim 1 , wherein a total content of the first polymer binder and the second polymer binder in the coating layer is 30 parts by weight or less based on 100 parts by weight of the coating layer. 9 . The separator for an electrochemical device according to claim 1 , wherein a total content of the inorganic particles in the coating layer is 70 parts by weight or more based on 100 parts by weight of the coating layer. 10 . The separator for an electrochemical device according to claim 1 , wherein the coating layer has a porosity of 33% by volume or more. 11 . The separator for an electrochemical device according to claim 1 , wherein the polyvinylidene-based binder having a hexafluoropropylene (HFP) content of less than 10 wt % is an aqueous binder. 12 . The separator for an electrochemical device according to claim 1 , wherein the dry adhesive force of the coating layer is 30 gf / 25 mm or more.

13. An electrochemical device comprising: A positive electrode, a negative electrode and a separator, wherein - the separator is a separator for an electrochemical device according to any one of claims 1 to 12; as well as - The separator is interposed between the positive electrode and the negative electrode.

14. A method for manufacturing a separator for an electrochemical device, the method comprising the following steps: mixing a slurry for preparing a coating, the slurry for preparing a coating comprising a first polymer binder in the form of particles, a second polymer binder in the form of particles, and inorganic particles; applying the slurry for preparing a coating layer to at least one surface of a porous polymer substrate; and drying the slurry for preparing the coating to form the coating, The second polymer binder is selected from: a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt % relative to the total weight of the polyvinylidene-based binder; a polyolefin-based binder; and combinations thereof. 15 . The method for producing a separator for an electrochemical device according to claim 14 , wherein the mixing step is performed for 1 hour or more and 3 hours or less.

16. The method for manufacturing a separator for an electrochemical device according to claim 14, wherein the first polymer binder is selected from: an acrylic binder; a polyvinylidene-based binder; a hybrid binder comprising an acrylic binder and a polyvinylidene-based binder; and combinations thereof, and The drying is performed at a temperature that differs from the glass transition temperature of the first polymer binder by no more than 20° C.

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