KR20240133930A - A sperator for an electrochemical device, an electrochemical device comprising the same and a manufacturing method thereof - Google Patents

Abstract

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

Description

{A SPERATOR FOR AN ELECTROCHEMICAL DEVICE, AN ELECTROCHEMICAL DEVICE COMPRISING THE SAME AND A MANUFACTURING METHOD THEREOF}

This invention claims the benefit of Korean Patent Application No. 10-2023-0026494 filed with the Korean Intellectual Property Office on February 28, 2023, the entire contents of which are incorporated herein by reference. The present invention relates to a separator for an electrochemical device, an electrochemical device comprising the same, and a method for manufacturing the same, and more particularly, to a separator for an electrochemical device capable of improving (reducing) resistance and maintaining porosity after lamination, wherein the separator comprises a polyvinylidene-based binder and/or a polyolefin-based binder containing a low content of hexafluoropropylene, an electrochemical device comprising the same, and a method for manufacturing the same.

Among the components of electrochemical devices, the separator is a polymer substrate with a porous structure located between the anode and cathode, which isolates the anode and cathode, prevents electrical short-circuiting between the two electrodes, and allows electrolytes and ions to pass. The separator itself does not participate in the electrochemical reaction, but its physical properties, such as wettability for the electrolyte, degree of porosity, and thermal shrinkage, affect the performance and safety of the electrochemical device.

Accordingly, various methods have been attempted to add a coating layer to a porous polymer substrate to enhance the physical properties of the membrane, and to change the properties of the coating layer by adding various substances to the coating layer. For example, an inorganic substance may be added to the coating layer to enhance (increase) the mechanical strength of the membrane, or an inorganic substance or hydrate may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate.

The separator can be bonded to the electrode through a lamination process, and a binder resin can be added to the slurry for the coating layer of the separator to secure adhesion between the electrode and the separator.

Meanwhile, there was a problem of increased resistance when including an acrylic binder in the coating layer or using a polyvinylidene fluoride (PVdF) binder. Furthermore, there was a problem of increased resistance at the coating layer interface due to the phenomenon of the binder included in the coating layer forming a film during the lamination process of joining the electrode and the separator.

Therefore, research was needed on a technology that does not reduce the porosity of the coating layer and does not increase the resistance of the separator itself even when the lamination process is performed.

The technical problem to be achieved by the present invention is to solve the problems of the prior art, and to prevent an increase in resistance at the interface due to film formation of a binder included in a coating layer that occurs in the step of laminating an electrode and a separator during the process of manufacturing a secondary battery, and to provide a separator for an electrochemical device capable of preventing an increase in resistance of the separator due to the use of an acrylic binder, an electrochemical device including the same, and a method for manufacturing the same.

However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer substrate and including a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles, wherein the second polymer binder is one selected from the group consisting of a polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% based on the total weight of the polyvinylidene-based binder, a polyolefin-based binder, and a combination thereof.

According to one embodiment of the present invention, the content of the inorganic particles in the region of the coating layer adjacent to the porous polymer substrate is greater than the content of the inorganic particles in the region of the coating layer facing the porous polymer substrate; the contents of the first polymer binder and the second polymer binder in the region of the coating layer adjacent to the porous polymer substrate are less than the contents of the first polymer binder and the second polymer binder in the region of the coating layer facing the porous polymer substrate; and when the thickness of the coating layer is divided in half, the region of the coating layer adjacent to the porous polymer substrate is half of the coating layer on the side adjacent to the porous polymer substrate; and the region of the coating layer opposing the porous polymer substrate may be half of the coating layer on the side spaced apart from the porous polymer substrate.

According to one embodiment of the present invention, the coating layer may further include a region including a first polymer binder in a film shape.

According to one embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene fluoride-based binder.

According to one embodiment of the present invention, the polyolefin-based binder may be polyethylene.

According to one embodiment of the present invention, the first polymer binder may be one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder including an acrylic binder and a polyvinylidene binder; and combinations thereof.

According to one embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene fluoride-based binder.

According to one embodiment of the present invention, the total content of the first polymer binder and the second polymer binder may be 30 parts by weight or less with respect to 100 parts by weight of the coating layer.

According to one embodiment of the present invention, the total content of the inorganic particles in the coating layer may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer.

According to one embodiment of the present invention, the porosity of the coating layer may be 33% by volume or more, and preferably may exceed 33% by volume.

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

According to one embodiment of the present invention, the dry adhesive strength of the coating layer may be 30 gf/25mm or more.

One embodiment of the present invention provides an electrochemical device including: an anode; a cathode; and a separator interposed between the anode and the cathode.

One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, the method comprising: a step of mixing a slurry for a coating layer including a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles; a step of applying the slurry for a coating layer on at least one surface of a porous polymer substrate; and a step of drying the slurry for a coating layer to form a coating layer; wherein the second polymer binder particles are one selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt%, a polyolefin-based binder, and a combination thereof.

According to one embodiment of the present invention, the mixing step may be mixing for 1 hour or more and 3 hours or less.

According to one embodiment of the present invention, the first polymer binder is one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder including an acrylic binder and a polyvinylidene binder; and combinations thereof, and a difference between the temperature of the drying step and the glass transition temperature of the first polymer binder particles may be 20° C. or less.

According to one embodiment of the present invention, a separator for an electrochemical device has a porosity that does not decrease even after lamination with an electrode, and can prevent an increase in resistance of the separator.

An electrochemical device according to one embodiment of the present invention can improve energy efficiency by reducing the resistance of a separator.

A method for manufacturing an electrochemical device according to one embodiment of the present invention can easily prevent an increase in the resistance of a separator, and prevent a decrease in the porosity of a separator by supporting the pressure applied in a lamination process with an electrode by polymer binder particles.

Figure 1 is a schematic diagram showing that the porosity of a separator for an electrochemical device according to one embodiment of the present invention is maintained after lamination.
Figure 2 is a flow chart of a method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention.
Figure 3 is a schematic diagram of an electrochemical device according to one embodiment of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, these are provided for illustrative purposes only, and the scope of the present invention is not limited by the following contents.

Unless otherwise specified, the detailed description defining or specifying embodiments is applicable to all inventions and is not limited to the description of specific inventions. That is, the present disclosure also refers to combinations of separately disclosed embodiments. Additionally, unless otherwise specified, the singular forms include plural forms throughout the detailed description and the appended claims.

In this specification, when a part is said to "comprise" a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated. However, unless explicitly stated otherwise, the terms "comprises" or "comprises" include "consists essentially of" and "comprises."

As used herein, the term "essentially comprising" means "comprising at least 70%", preferably "comprising at least 80%", most preferably "comprising at least 90%". When referring to amounts of components in a mixture of substances, the %'s are weight percent based on the total weight of each mixture. For example, a substance comprising essentially polyethylene comprises polyethylene in an amount of at least 70 weight percent based on the total weight of the substance.

In this specification, “A and/or B” means “A and B, or A or B.”

In this specification, when it is said that a component is "on", unless otherwise specifically stated, this does not exclude that other components are arranged in between, but rather that other components can be arranged. However, unless explicitly stated otherwise, "on" includes the meaning of "directly on", i.e., a situation in which no other components can be arranged in between.

In this specification, the term "having pores" or "porous" means that the object includes a plurality of pores and that the pores are interconnected with each other, thereby allowing gaseous and/or liquid fluids to pass from one side of the object to the other side.

In this specification, the separator has a porous characteristic including a large number of pores and acts as a porous ion-conducting barrier that allows ions to pass while blocking electrical contact between the cathode and the anode in an electrochemical device.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention provides an electrochemical device separator (100) including a porous polymer substrate (110); and a coating layer (130) provided on at least one surface of the porous polymer substrate (110) and including a first polymer binder (131) in particle form, a second polymer binder (133) in particle form, and inorganic particles (135), wherein the second polymer binder (133) is one selected from a polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% based on the total weight of the polyvinylidene-based binder, a polyolefin-based binder, and a combination thereof. That is, the coating layer is provided on one or both surfaces of the porous polymer substrate.

The separator (100) for an electrochemical device according to one embodiment of the present invention has a porosity that does not decrease even after lamination with an electrode, and can prevent an increase in resistance of the separator.

FIG. 1 is a schematic diagram showing that the porosity of a separator (100) for an electrochemical device according to one embodiment of the present invention is maintained after lamination. Referring to FIG. 1, the separator (100) for an electrochemical device according to one embodiment of the present invention will be described in detail.

According to one embodiment of the present invention, the electrochemical device separator (100) includes a porous polymer substrate (110). As described above, the electrochemical device separator (100) includes the porous polymer substrate (110), thereby allowing lithium ions to pass while blocking electrical contact between the positive and negative electrodes, and implementing a shutdown function at an appropriate temperature.

According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured using a polyolefin-based resin as a base resin. Examples of the polyolefin-based resin include polyethylene, polypropylene, polypentene, etc., and may include at least one of these. Preferably, the porous polymer substrate is composed of a polyethylene resin. A porous membrane, i.e., a membrane having a large number of pores, manufactured using such a polyolefin-based resin as a base resin can provide a shutdown function at an appropriate temperature.

According to one embodiment of the present invention, the weight average molecular weight of the polyolefin resin may be 500,000 or more and 1.5 million or less. Preferably, the weight average molecular weight of the polyolefin resin may be 900,000. By controlling the weight average molecular weight of the polyolefin resin within the above-described range, the compression resistance of the separator can be improved. Furthermore, when different types of polyolefin resins are mixed and used or the separator is formed with a multilayer structure of different types of polyolefin resins, the weight average molecular weight of the polyolefin resin can be calculated by adding the weight average molecular weight according to the content ratio of each polyolefin resin.

In this specification, “weight average molecular weight (Mw)” can be measured by gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies), and the measurement conditions can be set as follows.

- Column: PL Olexis (Polymer Laboratories)

- Solvent: TCB (Trichlorobenzene)

- Flow rate: 1.0 ml/min

- Sample concentration: 1.0 mg/ml

- Injection volume: 200 ㎕

- Column temperature: 160 ℃

- Detector: Agilent High Temperature RI detector

- Standard: Polystyrene (corrected by 3rd order function)

According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) in which a polyolefin resin is mixed with a plasticizer at a high temperature to form a single phase, the polymer material and the plasticizer are phase-separated during a cooling process, the plasticizer is extracted to form pores, and then stretching and heat-setting are performed. In addition, the porous polymer substrate using the polyolefin resin may have a core portion made of a mixture of polyethylene and polypropylene and a polyethylene skin portion laminated on both sides of the core portion.

According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the separation membrane (100) can be easily manufactured by a person skilled in the art by controlling the mixing ratio of the plasticizer, the stretching ratio, the heat-setting treatment temperature, etc. to conform to the scope of the present invention.

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

According to one embodiment of the present invention, the porosity of the porous polymer substrate may be 10 vol% or more and 90 vol% or less. The porosity of the porous polymer substrate may be 10 vol% or more, 20 vol% or more, 30 vol% or more, or 40 vol% or more. The porosity of the porous polymer substrate may be 90 vol% or less, 80 vol% or less, 70 vol% or less, or 60 vol% or less. Specifically, the porosity of the porous polymer substrate may be 10 vol% or more and 90 vol% or less, 20 vol% or more and 80 vol% or less, 30 vol% or more and 70 vol% or less, or 40 vol% or more and 60 vol% or less. By controlling the porosity of the porous polymer substrate within the above-described range, the lithium ion permeability of the separator may be controlled.

According to one embodiment of the present invention, the electrochemical device separator (100) includes a coating layer (130) provided on at least one surface of the porous polymer substrate (110). Specifically, the electrochemical device separator (100) may include a coating layer (130) provided on one or both surfaces of the porous polymer substrate (110). As described above, since the electrochemical device separator (100) includes a coating layer (130) provided on at least one surface of the porous polymer substrate (110), the heat resistance of the separator can be improved, the mechanical properties can be improved, and the shrinkage of the separator at high temperatures can be prevented, resulting in an electrical short circuit of the electrode.

According to one embodiment of the present invention, the coating layer (130) includes a particle-type first polymer binder (131), a particle-type second polymer binder (133), and an inorganic particle (135). As described above, since the coating layer (130) includes the particle-type first polymer binder (131), the particle-type second polymer binder (133), and the inorganic particle (135), the heat resistance of the separator is improved, the mechanical properties are improved, and the shrinkage of the separator at high temperatures and the occurrence of an electrical short circuit of the electrode are prevented, and pores can be formed inside the coating layer.

According to one embodiment of the present invention, the coating layer (130) may include a plurality of pores. Specifically, the coating layer may be a porous coating layer. More specifically, the coating layer may be a porous coating layer including a plurality of pores inside. As described above, since the coating layer includes a plurality of pores, it is possible to physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

According to one embodiment of the present invention, the coating layer may further include a region including a first polymer binder in a film shape. Specifically, as schematically shown in FIG. 1, when pressure and/or heat are applied in the process of laminating the electrode in the process of manufacturing the electrochemical device, a part of the first polymer binder used for the purpose of providing the coating layer may change into a film shape, i.e., an agglomerated structure. However, at least a part of the first polymer binder remains in a particle form.

According to one embodiment of the present invention, the coating layer (130) may be formed by inorganic particles (135) being bound by a first polymer binder (131), that is, a first polymer binder and a second polymer binder (133) in particle form and/or film form, and integrated within the coating layer. The pores within the coating layer (130) may be caused by an interstitial volume, which is an empty space between the inorganic particles.

In a method for manufacturing a separator for an electrochemical device, wherein the slurry for a coating layer is applied to at least one surface of the porous polymer substrate, the coating layer may be formed by the application of a single layer. Due to the separation of the inorganic particles on one side and the first polymer binder and the second polymer binder on the other side, the slurry for a coating layer includes an excess of inorganic particles in a portion adjacent to the porous polymer substrate and an excess of the first polymer binder and the second polymer binder in a portion spaced apart from the porous polymer substrate facing the porous polymer substrate, thereby improving the adhesion to the electrode and improving the porosity of the separator. In the present specification, an excess may mean a content exceeding 50 wt% in a corresponding portion, and the portion adjacent to the porous polymer substrate and the portion spaced apart from it may be separated based on an imaginary line corresponding to 1/2 of the thickness of the coating layer.

According to one embodiment of the present invention, in the electrochemical device separator (100), the content of inorganic particles in the region of the coating layer adjacent to the porous polymer substrate is greater than the content of inorganic particles in the region of the coating layer facing the porous polymer substrate; the contents of the first polymer binder and the second polymer binder in the region of the coating layer adjacent to the porous polymer substrate are smaller than the contents of the first polymer binder and the second polymer binder in the region of the coating layer facing the porous polymer substrate; and when the thickness of the coating layer is divided in half, the region of the coating layer adjacent to the porous polymer substrate is half of the coating layer on the side adjacent to the porous polymer substrate; and the region of the coating layer opposing the porous polymer substrate is half of the coating layer on the side spaced apart from the porous polymer substrate.

According to one embodiment of the present invention, the thickness of 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 one side of the porous polymer substrate (110), but is not particularly limited thereto. The thickness may be adjusted to an appropriate range by a person skilled in the art in terms of heat resistance or electrical resistance.

In one embodiment of the present invention, the thickness of the polymer substrate (110) and/or the coating layer (130), etc., can be measured by applying a contact-type thickness measuring device. The contact-type thickness measuring device can be, for example, VL-50S-B from Mitutoyo.

According to one embodiment of the present invention, the glass transition temperature (Tg) of the first polymer binder particle (131) may be 20° C. or more and 60° C. or less. The glass transition temperature is determined using a differential scanning calorimeter (DSC), and specific examples of the (DSC) device may be DSC (DSC823, METTLER TOLEDO), DSC (TA Instrument), and the like. Specifically, the glass transition temperature (Tg) of the first polymer binder may be 22° C. or more and 58° C. or less, 24° C. or more and 56° C. or less, 26° C. or more and 54° C. or less, 28° C. or more and 52° C. or less, 30° C. or more and 50° C. or less, 32° C. or more and 48° C. or less, 34° C. or more and 46° C. or less, 36° C. or more and 44° C. or less, or 38° C. or more and 42° C. By controlling the glass transition temperature (Tg) of the first polymer binder particles within the above-described range, the viscosity of the slurry for producing the coating layer can be controlled, thereby improving the convenience of battery production.

According to one embodiment of the present invention, the average diameter ( _D50 ) of the first polymer binder (131) in the particle form is not particularly limited, but is preferably in the range of 0.1 ㎛ or more and 1 ㎛ or less for the formation of a coating layer (130) with a uniform thickness and an appropriate porosity. Specifically, the average diameter (D50) of the first polymer binder particles (131) may be 0.2 ㎛ or more and 0.9 ㎛ or less, 0.3 ㎛ or more and 0.8 ㎛ or less, 0.4 ㎛ or more and 0.7 ㎛ or less, or 0.5 ㎛ or more and 0.6 ㎛ or less. By controlling the average diameter (D50) of the first polymer binder particles (131) within the above-described range, the dispersibility in a slurry prepared for manufacturing a coating layer can be improved, and the thickness of the formed coating layer can be reduced.

In the present 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 (e.g., Microtrac S3500) and the difference in the diffraction pattern according to the particle size is measured when the particles pass through the laser beam, thereby calculating the particle size distribution. By calculating the particle diameter at the point where it becomes 50% of the cumulative distribution of the number of particles according to the particle size in the measuring device, the D ₅₀ particle size can be measured. According to one embodiment of the present invention, the first polymer binder (131) may be one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder including an acrylic binder and a polyvinylidene binder; and a combination thereof. As described above, by selecting the first polymer binder (131) as one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder including an acrylic binder and a polyvinylidene binder; and a combination thereof, the acrylic binder can be formed into a film during the lamination process with the electrode, thereby improving the adhesive strength with the electrode.

According to one embodiment of the present invention, the hybrid binder may be a mixture in which an acrylic binder and a polyvinylidene binder are uniformly mixed, or a hybrid binder including an acrylic repeating unit and a polyvinylidene repeating unit, and may mean derived from the acrylic binder and the polyvinylidene binder.

According to one embodiment of the present invention, the acrylic binder included in the first polymer binder (131) may be a (meth)acrylic acid ester copolymer such as a methacrylic acid ester copolymer, an acrylonitrile acrylic acid ester copolymer, and a styrene acrylic acid ester copolymer; a (meth)acrylic resin, etc. Specifically, it may be at least one selected from the group consisting of a copolymer of styrene and butylacrylate, a polymer of ethylhexylacrylate, polyacrylonitrile, an acrylonitrile-styrene-butadiene copolymer, and polybutylacrylate. By selecting the acrylic binder included in the first polymer binder (131) from the above-described ones, the acrylic binder can be formed into a film during the lamination process with the electrode, thereby improving the adhesive strength with the electrode.

According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder (131) may be a polyvinylidene fluoride-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, an increase in the resistance of the separator can be prevented or reduced.

According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder particle (131) may have a hexafluoropropylene (HFP) content of 10 wt% or more. Specifically, the polyvinylidene-based binder included in the first polymer binder particle may have a hexafluoropropylene content of 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. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder in the first polymer binder particle within the above-described range, an increase in the resistance of the separator can be prevented or reduced. The content of the above hexafluoropropylene (HFP) monomer can be measured by ¹ H-NMR and/or ¹⁹ F-NMR.

According to one embodiment of the present invention, the total content of the first polymer binder (131) and the second polymer binder (133) may be 30 parts by weight or less with respect to 100 parts by weight of the coating layer (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 parts 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 with respect to 100 parts by weight of the coating layer (130). The total content of the first polymer binder (131) and the second polymer binder (133) may 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, based on 100 parts by weight of the coating layer (130). Specifically, the total content of the first polymer binder particles (131) and the second polymer binder particles (133) may be from 0 weight part to 29 weight parts, from 1 weight part to 27 weight parts, from 2 weight parts to 25 weight parts, from 3 weight parts to 22 weight parts, from 4 weight parts to 21 weight parts, from 5 weight parts to 20 weight parts, from 6 weight parts to 19 weight parts, from 7 weight parts to 18 weight parts, from 8 weight parts to 17 weight parts, from 9 weight parts to 16 weight parts, from 10 weight parts to 15 weight parts, from 11 weight parts to 14 weight parts, or from 12 weight parts to 13 weight parts, based on 100 weight parts of the coating layer (130). By controlling the total content of the first polymer binder (131) and the second polymer binder (133) within the above-described range, the ease of assembly can be improved in the process of assembling the electrode.

According to one embodiment of the present invention, the average diameter (D50) of the second polymer binder particles (133) is not particularly limited, but is preferably in the range of 0.1 ㎛ to 1 ㎛ for forming a coating layer (130) with a uniform thickness and an appropriate porosity. Specifically, the average diameter (D50) of the second polymer binder particles (133) may be 0.2 ㎛ to 0.9 ㎛, 0.3 ㎛ to 0.8 ㎛, 0.4 ㎛ to 0.7 ㎛, or 0.5 ㎛ to 0.6 ㎛. By controlling the average diameter (D50) of the second polymer binder particles (133) within the above-described range, the dispersibility in the slurry prepared for manufacturing the coating layer can be improved, and the thickness of the formed coating layer 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 particle size. The particle size can be measured using a laser diffraction method. Specifically, the target powder is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and the difference in the diffraction pattern according to the particle size is measured when the particles pass through the laser beam, thereby calculating the particle size distribution. By calculating the particle diameter at the point where 50% of the cumulative distribution of the number of particles according to particle size in the measuring device is reached, the D ₅₀ particle size can be measured.

According to one embodiment of the present invention, the second polymer binder (133) is one selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt%, a polyolefin-based binder, and a combination thereof. As described above, by selecting the second polymer binder (133) as one selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt%, a polyolefin-based binder, and a combination thereof, the porosity of the separation membrane can be maintained. Specifically, referring to the above Drawing 1, there is a problem that the acrylic binder particles (the first polymer binder in particle form) change into a film form due to the pressure applied during the lamination process with the electrode, thereby reducing the porosity of the coating layer (130) and hindering the movement of ions through the pores, thereby increasing the resistance. However, by selecting a polyvinylidene binder or/and a polyolefin binder containing a low content of hexafluoropropylene as described above as the second polymer binder in particle form (133), the second polymer binder in particle form (133) can support the pressure applied during the lamination process with the electrode to maintain the porosity, thereby allowing lithium ions to move through the separator, thereby preventing an increase in resistance.

According to one embodiment of the present invention, in the second polymer binder (133), the polyvinylidene-based binder may have a hexafluoropropylene content of less than 10 wt% with respect to the total weight of the polyvinylidene-based binder. In the second polymer binder (133), the polyvinylidene-based binder may have a hexafluoropropylene content 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 with respect to the total weight of the polyvinylidene-based binder. In the second polymer binder (133), the polyvinylidene-based binder may have a content of hexafluoropropylene 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, the polyvinylidene-based binder may have a hexafluoropropylene content of more than 0 wt% and less than 10 wt%, of more than 0.1 wt% and less than 9.9 wt%, of more than 0.5 wt% and less than 9.5 wt%, of more than 1.0 wt% and less than 9.0 wt%, of more than 1.5 wt% and less than 8.5 wt%, of more than 2.0 wt% and less than 8.0 wt%, of more than 2.5 wt% and less than 7.5 wt%, of more than 3.0 wt% and less than 7.0 wt%, of more than 3.5 wt% and less than 6.5 wt%, of more than 4.0 wt% and less than 6.0 wt%, or of more than 4.5 wt% and less than 5.5 wt%. Preferably, the polyvinylidene-based binder may have a hexafluoropropylene content of 5.0 wt%. By controlling the content of hexafluoropropylene included in the polyvinylidene-based binder within the above-described range, the porosity of the separator can be maintained, thereby improving the resistance of the separator. In the present specification, the degree of substitution of the polyvinylidene-based binder may mean the weight ratio of hexafluoropropylene included. The content of the hexafluoropropylene (HFP) monomer can be measured by ¹ H-NMR and/or ¹⁹ F-NMR.

According to one embodiment of the present invention, the polyvinylidene-based binder in the second polymer binder (133) may be a polyvinylidene fluoride (PVdF)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based binder, the porosity of the separator can be maintained, thereby improving the resistance of the separator. Furthermore, the polyvinylidene-based binder, which is the second polymer binder, may be the same as or different from the polyvinylidene-based binder included in the first polymer binder.

According to one embodiment of the present invention, the polyolefin-based binder in the second polymer binder (133) may be polyethylene. As described above, by selecting polyethylene as the polyolefin-based binder in the second polymer binder (133), the porosity of the separator can be maintained, thereby improving the resistance of the separator.

According to one embodiment of the present invention, the weight ratio of the first polymer binder (131) and the second polymer binder (133) included 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) included in the coating layer may be 2:8 to 8:2, 3:7 to 7:3, or 4:6 to 6:4. By controlling the weight ratio of the first polymer binder (131) and the second polymer binder (133) included in the coating layer within the above-described range, an increase in the resistance of the separator can be prevented or reduced, and the ease of assembly can be improved in the process of assembling the electrode.

According to one embodiment of the present invention, when a combination of a polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% and a polyolefin-based binder is used in the second polymer binder (133), the weight ratio of the polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% and the polyolefin-based binder may be 1:9 to 9:1. Specifically, when a combination of a polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% and a polyolefin-based binder is used in the second polymer binder (133), the weight ratio of the polyvinylidene-based binder having a content of hexafluoropropylene 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. By controlling the weight ratio of the polyvinylidene-based binder and the polyolefin-based binder in which the content of the hexafluoropropylene of the second polymer binder (133) is less than 10 wt% within the above-described range, an increase in the resistance of the separator can be prevented or reduced, and the ease of assembly can be improved in the process of assembling the electrode.

According to one embodiment of the present invention, 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 invention are not particularly limited as long as they do not undergo oxidation and/or reduction reactions within the operating voltage range of the applied electrochemical device (e.g., 0 V to 5 V based on Li/Li ⁺ ).

According to one embodiment of the present invention, the content of the inorganic particles (135) may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer (130). The content of the inorganic particles (135) 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, 85 parts by weight or more with respect to 100 parts by weight of the coating layer (130). The content of the above-mentioned inorganic particles (135) may 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, relative to 100 parts by weight of the above-mentioned coating layer (130). Specifically, the content of the inorganic particles (135) 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, based on 100 parts by weight of the coating layer (130). By controlling the content of the inorganic particles (135) within the above-described range, the heat resistance of the separator can be improved.

According to one embodiment of the present invention, when high-dielectric constant inorganic particles are used, the inorganic particles can contribute to increasing the dissociation of an electrolyte salt, for example, a lithium salt, in a liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution. For the above-mentioned reasons, the inorganic particles may be inorganic particles having a dielectric constant of 5 or higher, inorganic particles having a lithium ion transport capability, or a mixture thereof.

According to one embodiment of the present invention, non-limiting examples of the inorganic particles (135) include BaTiO ₃ , Pb(Zr,Ti)O ₃ (PZT), Pb _1-x La _x Zr _1-y Ti _y O ₃ (PLZT, 0<x<1, 0<y<1), Pb(Mg _1/3 Nb _2/3 )O ₃ -PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, Mg(OH) ₂ , NiO, CaO, ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC, Al(OH) ₃ , TiO ₂ , aluminum peroxide, zinc tin hydroxide (ZnSn(OH) ₆ ), Examples thereof include zinc oxide (Zn ₂ SnO ₄ , ZnSnO ₃ ), antimony trioxide (Sb ₂ O ₃ ), antimony tetroxide (Sb ₂ O ₄ ), and antimony pentoxide (Sb ₂ O ₅ ), and may include one or more of these.

According to one embodiment of the present invention, the content of the inorganic particles (135) may be 70 parts by weight or more with respect to 100 parts by weight of the coating layer (130). The content of the inorganic particles (135) 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, 85 parts by weight or more with respect to 100 parts by weight of the coating layer (130). The content of the above-mentioned inorganic particles (135) may 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, relative to 100 parts by weight of the above-mentioned coating layer (130). Specifically, the content of the inorganic particles (135) 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, based on 100 parts by weight of the coating layer (130). By controlling the content of the inorganic particles (135) within the above-described range, assembly of the electrode can be facilitated.

According to one embodiment of the present invention, the average diameter ( _D50 ) of the inorganic particles (135) is not particularly limited, but is preferably in the range of 0.3 ㎛ or more and 1 ㎛ or less for the formation of a coating layer (130) with a uniform thickness and an appropriate porosity. Specifically, the average diameter (D50) of the inorganic particles (135) may be 0.2 ㎛ or more, 0.3 ㎛ or more, 0.4 ㎛ or more, or 0.5 ㎛ or more. The average diameter (D50) of the inorganic particles (135) may be 0.9 ㎛ or less, 0.8 ㎛ or less, 0.7 ㎛ or less, or 0.6 ㎛ or less. Specifically, the average diameter (D50) of the inorganic particles (135) may be 0.2 ㎛ or more and 0.9 ㎛ or less, 0.3 ㎛ or more and 0.8 ㎛ or less, 0.4 ㎛ or more and 0.7 ㎛ or less, or 0.5 ㎛ or more and 0.6 ㎛ or less. The average diameter (D50) of the inorganic particles (135) is preferably 0.5 ㎛. Specifically, when it is less than 0.3 ㎛, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer may be reduced, and when it exceeds 1 ㎛, the thickness of the formed coating layer may be increased.

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 particle size. The particle size can be measured using a laser diffraction method. Specifically, the target powder is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and the difference in the diffraction pattern according to the particle size is measured when the particles pass through the laser beam, thereby calculating the particle size distribution. By calculating the particle diameter at the point where 50% of the cumulative distribution of the number of particles according to particle size in the measuring device is reached, the D ₅₀ particle size can be measured.

According to one embodiment of the present invention, the porosity of the coating layer (130) may be 30 vol% or more. The porosity of the coating layer (130) may be 30 vol% or more, 32 vol% or more, 33 vol% or more, 34 vol% or more, 36 vol% or more, 38 vol% or more, 40 vol% or more, 42 vol% or more, 44 vol% or more, 46 vol% or more, 48 vol% or more. The porosity of the coating layer (130) may be 70 vol% or less, 68 vol% or less, 66 vol% or less, 64 vol% or less, 62 vol% or less, 60 vol% or less, 58 vol% or less, 56 vol% or less, 54 vol% or less, 52 vol% or less. Specifically, the porosity of the coating layer (130) may be 30 vol% or more and 70 vol% or less, 32 vol% or more and 68 vol% or less, 34 vol% or more and 66 vol% or less, 36 vol% or more and 64 vol% or less, 38 vol% or more and 62 vol% or less, 40 vol% or more and 60 vol% or less, 42 vol% or more and 58 vol% or less, 44 vol% or more and 56 vol% or less, 46 vol% or more and 54 vol% or less, or 48 vol% or more and 52 vol% or less. By controlling the porosity of the coating layer (130) within the above-described range, the movement of ions in the separator can be maintained and an increase in the resistance of the separator can be prevented. Specifically, when the porosity is 70 vol% or less, mechanical properties capable of withstanding the pressing process for bonding with the electrode can be secured, and also, the surface opening ratio does not become too high, making it suitable for securing adhesive strength. Meanwhile, if the porosity is 30 volume% or more, it is advantageous from the perspective of ion permeability.

In this specification, “porosity” means the ratio of the volume occupied by pores to the total volume, and uses volume% as its unit, and can be used interchangeably with terms such as void ratio and porosity.

In this specification, the porosity may correspond to a value obtained by subtracting a volume converted into the weight and density of each component of the porous polymer substrate (110) and/or the coating layer (130) from the volume calculated in the thickness, width, and length of the porous polymer substrate (110) and/or the coating layer (130).

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

According to one embodiment of the present invention, the polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% may be an aqueous binder. Specifically, by selecting the polyvinylidene-based binder having a content of hexafluoropropylene of less than 10 wt% as an aqueous binder, the resistance of the separator can be prevented from increasing. In the present specification, “aqueous binder” may mean a binder that is soluble in water and has a solubility index similar to that of water.

According to one embodiment of the present invention, the dry adhesion of the coating layer may be 30 gf/25mm or more. The dry adhesion of the coating layer may be 35 gf/25mm or more, 40 gf/25mm or more, 45 gf/25mm or more, 50 gf/25mm or more, 55 gf/25mm or more, 60 gf/25mm or more. The dry adhesion of the coating layer may be 100 gf/25mm or less, 95 gf/25mm or less, 90 gf/25mm or less, 85 gf/25mm or less, 80 gf/25mm or less, 75 gf/25mm or less, 70 gf/25mm or less. Specifically, the dry adhesion of the coating layer may be 30 gf/25mm or more and 100 gf/25mm or less, 35 gf/25mm or more and 95 gf/25mm or less, 40 gf/25mm or more and 90 gf/25mm or less, 45 gf/25mm or more and 85 gf/25mm or less, 50 gf/25mm or more and 80 gf/25mm or less, 55 gf/25mm or more and 75 gf/25mm or less, or 60 gf/25mm or more and 70 gf/25mm or less. By controlling the dry adhesion of the coating layer as described above, the ease of assembly can be improved in the process of assembling the electrode.

In this specification, the dry adhesive strength of the coating layer may mean the strength measured by cutting the separator into 70 mm (length) x 25 mm (width), laminating the prepared electrode and separator using a press under the conditions of 60°C, 6.5 MPa, and 1 sec to produce a specimen, fixing the prepared specimen to a glass plate using double-sided tape, and then placing it so that the electrode faces the glass plate, and then peeling the separator portion of the specimen at an angle of 180° at a speed of 150 mm/min at 25°C.

According to one embodiment of the present invention, an adhesive polymer binder may be provided on the coating layer (130). Specifically, the adhesive polymer binder may be located on the opposite side of the coating layer adjacent to the porous polymer substrate. More specifically, the opposite side of the coating layer may be covered by the adhesive polymer binder. As described above, by providing the adhesive polymer binder on the coating layer (130), dry adhesion and wet adhesion with the electrode can be improved.

According to one embodiment of the present invention, the adhesive polymer binder may be in particle form, dissolved form, or a combination thereof. As used herein, “particle form” may mean that the adhesive polymer binder maintains the shape of a particle by not being dissolved by the electrolyte injected into the battery. As used herein, “dissolved type” may mean that the adhesive polymer binder does not maintain the shape of a particle by being dissolved by the electrolyte injected into the battery. By selecting the adhesive polymer binder from the above, the dry adhesion and wet adhesion with respect to the electrode can be improved.

According to one embodiment of the present invention, an adhesive polymer binder may be provided on a portion of the coating layer (130). As described above, by providing an adhesive polymer binder on a portion of the coating layer (130), dry adhesion and wet adhesion with the electrode can be improved.

According to one embodiment of the present invention, the adhesive polymer binder may be provided in an area of more than 0% and less than 100% of the total area of the coating layer. Specifically, the area in which the adhesive polymer binder is provided on the coating layer may be 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 of the total area of the coating layer. By controlling the area in which the adhesive polymer binder is provided on the coating layer within the above-described range, dry adhesion and wet adhesion with respect to the electrode can be improved.

According to one embodiment of the present invention, the adhesive polymer binder may be the same as or different from the first polymer binder and the second polymer binder. By selecting the type of the adhesive polymer binder as described above, the adhesive strength between the coating layer and the adhesive polymer binder can be controlled, the adhesive polymer binder can be prevented from being dissolved by the electrolyte, and the resistance of the battery can be minimized.

According to one embodiment of the present invention, the adhesive polymer binder can be provided on a part of the coating layer by a spray method, bar coating, spin coating, or dip coating method. By selecting a method for providing the adhesive polymer binder from those described above, the adhesive polymer binder can be easily positioned on the coating layer.

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

A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can easily prevent an increase in the resistance of the separator, and prevent a decrease in the porosity of the separator by supporting the pressure applied in the lamination process with the electrode by the polymer binder particles.

FIG. 2 is a flow chart of a method for manufacturing a separator (100) for an electrochemical device according to one embodiment of the present invention. Referring to FIG. 2, a method for manufacturing a separator (100) for an electrochemical device according to one embodiment of the present invention will be specifically described. In the description of the method for manufacturing a separator (100) for an electrochemical device according to one embodiment of the present invention, any content that overlaps with the description of the separator for an electrochemical device will be omitted.

According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S10) of mixing a slurry for a coating layer including first polymer binder particles (131, i.e., first polymer binder in particle form), second polymer binder particles (133, i.e., second polymer binder in particle form), and inorganic particles (135). By including the step (S10) of mixing a slurry for a coating layer including first polymer binder particles (131), second polymer binder particles (133), and inorganic particles (135) as described above, a coating layer can be easily formed on the separator.

According to one embodiment of the present invention, a polymer binder resin, that is, a first polymer binder particle (131) and a second polymer binder particle (133), may be dispersed in an appropriate dispersion medium to prepare a polymer emulsion, thereby providing a slurry for a coating layer. It is preferable that the dispersion medium have a solubility index similar to that of the binder polymer to be used and a low boiling point. This is to facilitate uniform mixing and subsequent removal of the dispersion medium. Non-limiting examples of usable dispersion medium include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof. Preferably, the solvent may be water. In this specification, the dispersion medium may mean a solvent used in the process of preparing a slurry.

According to one embodiment of the present invention, inorganic particles (135) can be added and dispersed in the polymer emulsion. The content ratio of the inorganic particles and 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 finally manufactured according to one embodiment of the present invention.

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

The slurry for the above coating layer may include the first polymer binder particles (131), the second polymer binder particles (133), inorganic particles (135), and a dispersion medium.

The mixing of the slurry for the above coating layer may be performed for 1 hour or more and 3 hours or less.

According to one embodiment of the present invention, the content of the solids of the slurry for the coating layer may be 10 wt% or more and 50 wt% or less with respect to 100 wt% of the slurry for the coating layer. Specifically, the content of the solids of the slurry for the coating layer may 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. By controlling the content of the solids of the slurry for the coating layer within the above-described range, the workability of the coating layer manufacturing process can be improved.

According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S30) of applying the slurry for the coating layer on at least one surface of the porous polymer substrate (100). By including the step of applying the slurry for the coating layer on at least one surface of the porous polymer substrate (110) as described above, the coating layer (130) can be formed with a single application, and due to the separation between the inorganic particles and the polymer binder particles of the slurry for the coating layer, a portion close to the porous polymer substrate (110) contains an excess of inorganic particles (135), and a portion far from the porous polymer substrate (110) contains an excess of polymer binder particles (131, 133), thereby improving adhesive strength with the electrode and improving the porosity of the separator. In the present specification, the excessive presence may mean a content exceeding 50 wt% in the relevant portion, and the portion close to and far from the porous polymer substrate (110) may be distinguished based on an imaginary line that accounts for 1/2 of the thickness of the coating layer.

According to one embodiment of the present invention, the method of applying the slurry for the coating layer to the surface of the porous polymer substrate (110) is not particularly limited to any one method, and a conventional method known in the art can be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, or a mixed method thereof can be used.

According to one embodiment of the present invention, the method for manufacturing the electrochemical device separator (100) includes a step (S50) of drying the slurry for the coating layer to provide a coating layer (130). As described above, by including the step (S50) of drying the slurry for the coating layer to provide a coating layer (130), damage to the coating layer can be minimized, and the solvent included in the slurry can be easily removed.

According to one embodiment of the present invention, the drying process appropriately sets time conditions so as to minimize occurrence of surface defects in the coating layer (130). The drying may be performed using a drying auxiliary device such as a drying oven or hot air within an appropriate range.

According to one embodiment of the present invention, the temperature of the drying step may be 25° C. or higher and 75° C. or lower. The temperature of the drying step may be 30° C. or higher, 35° C. or higher, 40° C. or higher, or 45° C. or higher. The temperature of the drying step may be 70° C. or lower, 65° C. or lower, 60° C. or lower, or 55° C. or lower. Specifically, the temperature of the drying step 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. By controlling the temperature of the drying step within the above-described range, it is possible to prevent denaturation of the porous polymer substrate and effectively remove the dispersion medium.

According to one embodiment of the present invention, the second polymer binder particle (133) is one selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt%, a polyolefin-based binder, and a combination thereof. As described above, by selecting the second polymer binder particle (133) as one selected from a polyvinylidene-based binder having a hexafluoropropylene content of less than 10 wt%, a polyolefin-based binder, and a combination thereof, the porosity of the separation membrane can be maintained. Specifically, referring to the above Drawing 1, there is a problem that, during the process of laminating with the electrode, the acrylic binder particles change into a film shape, which reduces the porosity of the coating layer and hinders the movement through the pores, thereby increasing the resistance. However, as described above, by selecting a polyvinylidene binder or/and a polyolefin binder containing a low content of hexafluoropropylene as the second polymer binder particle (133), the second polymer binder particle (133) can support the pressure applied during the lamination process with the electrode, thereby maintaining the porosity, and thereby allowing ions to move through the membrane, thereby preventing an increase in resistance.

According to one embodiment of the present invention, the mixing step may be mixing for 1 hour or more and 3 hours or less. The mixing step may be mixing for 1.5 hours or more. The mixing step may be mixing for 2.5 hours or less. Preferably, the mixing step may be mixing for 1.5 hours or more and 2.5 hours or less or about 2 hours. By controlling the mixing time of the slurry as described above, the dispersibility of the inorganic particles (135) included in the slurry for the coating layer 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 the coating layer can be improved.

According to one embodiment of the present invention, the first polymer binder particle (131) used in the method may be one selected from the group consisting of acrylic binder particles; polyvinylidene binder particles; hybrid binder particles including an acrylic binder and a polyvinylidene binder; and combinations thereof. As described above, by selecting the first polymer binder particle (131) as one selected from the group consisting of acrylic binder particles; polyvinylidene binder particles; hybrid binder particles including an acrylic binder and a polyvinylidene binder; and combinations thereof, the acrylic binder may be formed into a film during the lamination process with the electrode, thereby improving adhesion to the electrode.

According to one embodiment of the present invention, the difference between the temperature of the drying step (S50) and the glass transition temperature of the first polymer binder particles may be 20°C or less. The difference between the temperature of the drying step (S50) and the glass transition temperature of the first polymer binder particles may be more 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 of the drying step (S50) 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 of the drying step and the glass transition temperature of the first polymer binder particles may be 0°C to 20°C, 1°C to 19°C, 2°C to 18°C, 3°C to 17°C, 4°C to 16°C, 5°C to 15°C, 6°C to 14°C, 7°C to 13°C, 8°C to 12°C, or 9°C to 11°C. By controlling the difference between the temperature of the drying step and the glass transition temperature of the first polymer binder particles within the above-described range, the first polymer binder particles can be prevented from melting and being arranged adjacent to the porous polymer substrate.

According to one embodiment of the present invention, the separator (100) is interposed between the cathode and the anode and is manufactured into an electrochemical device by a lamination process that applies heat and/or pressure to bind them. In one embodiment of the present invention, the lamination process can be performed by a roll press device including a pair of pressure rollers. That is, the cathode, the separator, and the anode can be sequentially laminated and inserted between the pressure rollers to achieve interlayer bonding. At this time, the lamination process can be performed by a hot pressurizing method.

One embodiment of the present invention provides an electrochemical device (1000) including: an anode (300); a cathode (500); and a separator (100) interposed between the anode (300) and the cathode (500).

An electrochemical device (1000) according to one embodiment of the present invention can improve energy efficiency by reducing the resistance of a separator.

FIG. 3 is a schematic diagram of an electrochemical device (1000) according to one embodiment of the present invention. Referring to FIG. 3, an electrochemical device (1000) according to one embodiment of the present invention will be described in detail.

According to one embodiment of the present invention, the electrochemical device is a device that converts chemical energy into electrical energy by an electrochemical reaction, and is a concept that encompasses primary batteries and secondary batteries. In the present specification, the secondary battery is capable of charging and discharging, and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples thereof include, but are not limited to, a non-aqueous electrolyte secondary battery including a liquid electrolyte, an all-solid-state battery including a solid electrolyte, a lithium polymer battery including a gel polymer electrolyte, and a lithium metal battery using lithium metal as an anode.

According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as a lithium manganese composite oxide (LiMn ₂ O ₄ , LiMnO ₂ , etc.), lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; lithium manganese oxide having the chemical formula Li _1+x Mn _2-x O ₄ (wherein, x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , etc.; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxide such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ ; Ni-site type lithium nickel oxide represented by the chemical formula LiNi _1-x M _x O ₂ (wherein, M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3); lithium manganese composite oxide represented by the chemical formula LiMn ₁ -x _{M x} O ₂ (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn ₂ O ₄ in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ may include one or a mixture of two or more thereof.

According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes _, as the negative _electrode active material, carbon such as lithium metal oxide, non-graphitizable carbon, and graphite _carbon ; metal composite oxides such as _LixFe2O3 (0≤x≤1), LixWO2 ₍ 0≤x≤1), SnxMe1 _{- xMe'yOz} (Me: Mn, Fe, Pb, Ge; _Me ': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogen; 0<x≤1;1≤y≤3;1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; It may include one or a mixture of two or more selected from metal _{oxides such as} SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O 4 , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi 2 O ₄ , and Bi ₂ O ₅ ; conductive polymers such as polyacetylene ; Li-Co-Ni based materials ; and titanium oxides.

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

According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

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

According to one embodiment of the present invention, the positive electrode slurry for producing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (ADC-01, LG Chemical).

According to one embodiment of the present invention, the content of the dispersant included in the positive electrode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant included in the positive electrode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the positive electrode slurry.

According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei, Japan).

According to one embodiment of the present invention, the content of the dispersant included in the cathode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the cathode slurry. Specifically, the content of the dispersant included in the cathode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the cathode slurry.

According to one embodiment of the present invention, an electrochemical device prepared as described above can be placed in an appropriate case and an electrolyte solution is injected to manufacture a battery.

According to one embodiment of the present invention, the electrolyte is a salt having a structure such as A ⁺ B ^- , wherein A ⁺ contains an ion formed by an alkali metal cation such as Li ⁺ , Na ⁺ , K ⁺ or a combination thereof, and B ^- contains an ion formed by an anion such as PF ₆ ^- , BF ₄ ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , AsF ₆ ^- , CH ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N(CF ₃ SO ₂ ) ₂ ^- , C(CF ₂ SO ₂ ) ₃ ^- or a combination thereof, and the salt is selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, Dissolved or dissociated in an organic solvent consisting of, but not limited to, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone (γ butyrolactone), or a mixture thereof.

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

Hereinafter, the present invention will be described in detail by way of examples in order to specifically explain the present invention. However, the examples according to the present invention may be modified in various different forms, and the scope of the present invention is not construed as being limited to the examples described below. The examples in this specification are provided to more completely explain the present invention to a person having average knowledge in the art.

<Example 1>

Polyethylene resin (weight average molecular weight 900,000) was extruded and a porous polymer substrate (total thickness of approximately 9 ㎛, porosity of 40 volume%) was manufactured using a wet method.

A copolymer of styrene and butyl acrylate (glass transition temperature: 40°C), which is an acrylic binder with a particle size of 500 nm, was used as the first polymer binder particle, a polyvinylidene binder with a particle size of 500 nm, a copolymer of PVdF and HFP with a degree of substitution (weight ratio of HFP in the PVdF polymer) of 5 wt%, and polyethylene with a particle size of 500 nm were mixed and used in a weight ratio of 1:1. The first polymer binder particles, the second polymer binder particles, and inorganic particles ( _{Al2O3 ,} particle size of 500 nm) were put into water and mixed and dispersed for 2 hours to prepare a slurry for a coating layer (solid content concentration of 30%). The weight ratio of the first polymer binder particles and the second polymer binder particles was 1:1, and the weight ratio of the polymer binder particles and the inorganic particles was 25:75.

The dispersion was applied to both sides of the surface of the porous polymer substrate using a doctor blade by bar coating, and dried with air at 50°C using a heat gun.

<Example 2>

A separation membrane was manufactured in the same manner as in Example 1, except that only a PVDF-based binder containing 9 wt% of HFP was used as the second polymer binder particle.

<Example 3>

A separation membrane was manufactured in the same manner as in Example 1, except that only polyethylene was used as the second polymer binder particle.

<Example 4>

In the coating layer of the membrane manufactured in Example 1, styrene-butyl acrylate (glass transition temperature 40° C., particle size 500 nm), which is an acrylic binder and an adhesive polymer binder, was spray-coated so that the adhesive polymer binder was provided on 50% of the area of the coating layer.

<Comparative Example 1>

A membrane was manufactured in the same manner as in Example 1, except that the second polymer binder particles were not included.

<Comparative Example 2>

A membrane was manufactured in the same manner as in Example 1, except that a polymer of 2-ethylhexyl acrylate (2-EHA), an acrylic binder, was used as the second polymer binder particle.

<Manufacturing of electrochemical devices>

1) Manufacturing of the anode

A slurry for a cathode active material layer was prepared by mixing a cathode active material (LiNi _0.8 Mn _0.1 Co _0.1 O ₂ ), a conductive agent (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66 and having a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied onto the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture a cathode having a cathode active material layer (thickness 120 μm).

2) Manufacturing of cathode

Graphite (natural graphite and artificial graphite blend), conductive agent (carbon black), dispersant (polyvinylpyrrolidone, Junsei, Japan), and binder resin (PVDF-HFP and PVDF blend) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for an anode active material layer having a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied onto the surface of a copper film (thickness 10 ㎛) and dried to manufacture an anode having an anode active material layer (thickness 120 ㎛).

3) Lamination process

The separators of the examples and comparative examples were interposed between the manufactured cathodes and anodes, and a lamination process was performed to obtain an electrode assembly. The lamination process was performed using a hot press at 70°C and 5.2 MPa for 10 seconds.

<Experimental Example 1: Measurement of porosity of coating layer>

The porosity was calculated using [Mathematical Formula 1] and [Mathematical Formula 2] below.

[Mathematical Formula 1]

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

[Mathematical formula 2]

Apparent density (g/cm ³ ) = {Weight of coating layer [g] / Thickness of coating layer [cm] × Area of coating layer [cm ² ])}

For each example and comparative example, three samples measuring 5 cm in the MD/TD direction were obtained from the coating layer. The thickness of the coating layer was measured at five points for each sample, and the average value was used, and the weight of each sample was measured using a balance. The average value of the three samples was calculated and applied to the mathematical equations 1 and 2 to calculate the porosity. Meanwhile, the true density of each sample was applied based on theoretically confirmed values, such as molecular weight for each applied component. In this case, the true density is a value calculated from the volume and mass, and the volume is measured so as not to include closed pores in the coating layer.

<Experimental Example 2: Membrane resistance measurement>

Resistance was measured by sandwiching each membrane substrate between SUS and injecting electrolyte to manufacture coin cells and measuring resistance (ER) by EIS method. At this time, the frequency was in the range of 100000 to 10000 Hz. The electrolyte is a non-aqueous solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a ratio of 3:7 and LiPF ₆ mixed at a concentration of 1 M.

Porosity of coating layer (vol%) Resistance of the membrane (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

Referring to Table 1 above, it was confirmed that Examples 1 to 3 including a polyvinylidene binder or a polyolefin binder containing a low content of hexafluoropropylene all implemented a resistance of the separator of 0.73 Ω or less and a porosity of the coating layer of 35 volume% or more.

In this regard, it was confirmed that Comparative Example 1, which did not include the second polymer binder particles, had a reduced porosity and an increased resistance of the membrane. Furthermore, it was confirmed that Comparative Example 2, which used only an acrylic binder as the second polymer binder particles, also had a reduced porosity and an increased resistance of the membrane.

Finally, according to one embodiment of the present invention, by including a polyvinylidene binder or a polyolefin binder containing a low content of hexafluoropropylene in the coating layer, an increase in the resistance of the separator can be prevented or reduced, and the porosity of the coating layer can be improved.

100: Separator for electrochemical devices
110: Porous polymer substrate
130: Coating layer
131: First polymer binder particle
133: Second polymer binder particle
135: Inorganic particles
300: Bipolar
500: Negative
1000: Electrochemical Devices

Claims (16)

Porous polymer substrate; and
It is provided on at least one surface of the porous polymer substrate, and includes a coating layer including a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles.
A separator for an electrochemical device, wherein the second polymer binder is selected from the group consisting of a polyvinylidene-based binder, a polyolefin-based binder, and a combination thereof, wherein the content of hexafluoropropylene (HFP) is less than 10 wt% based on the total weight of the polyvinylidene-based binder. In claim 1,
The content of inorganic particles in the region of the coating layer adjacent to the porous polymer substrate is greater than the content of inorganic particles in the region of the coating layer facing the porous polymer substrate;
The content of the first polymer binder and the second polymer binder in the region of the coating layer adjacent to the porous polymer substrate is smaller than the content of the first polymer binder and the second polymer binder in the region of the coating layer facing the porous polymer substrate;
An electrochemical device separator, wherein when the thickness of the coating layer is divided in half, an area of the coating layer adjacent to the porous polymer substrate is half of the coating layer on the side adjacent to the porous polymer substrate, and an area of the coating layer opposing the porous polymer substrate is half of the coating layer spaced apart from the porous polymer substrate. In claim 1,
A separator for an electrochemical device, wherein the coating layer further includes a region comprising a first polymer binder in a film shape. A separator for an electrochemical device according to claim 1, wherein the polyvinylidene-based binder is a polyvinylidene fluoride-based binder. In claim 1,
A separator for an electrochemical device, wherein the polyolefin binder is polyethylene. In claim 1,
A separator for an electrochemical device, wherein the first polymer binder is one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder including an acrylic binder and a polyvinylidene binder; and combinations thereof. In claim 6,
A separator for an electrochemical device, wherein the polyvinylidene-based binder is a polyvinylidene fluoride-based binder. In claim 1,
A separator for an electrochemical device, wherein the total content of the first polymer binder and the second polymer binder in the coating layer is 30 parts by weight or less with respect to 100 parts by weight of the coating layer. In claim 1,
A separator for an electrochemical device, wherein the total content of the inorganic particles in the coating layer is 70 parts by weight or more with respect to 100 parts by weight of the coating layer. In claim 1,
A separator for an electrochemical device, wherein the porosity of the coating layer is 33% by volume or more. In claim 1,
A separator for an electrochemical device, wherein the polyvinylidene binder having a content of less than 10 wt% of the above hexafluoropropylene (HFP) is an aqueous binder. In claim 1,
A separator for an electrochemical device, wherein the dry adhesion of the coating layer is 30 gf/25 mm or more. An electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode, the separator being any one of claims 1 to 12. A step of mixing a slurry for a coating layer comprising a first polymer binder in particle form, a second polymer binder in particle form, and inorganic particles;
A step of applying the slurry for the coating layer on at least one surface of a porous polymer substrate; and
A step of drying the slurry for the coating layer to provide a coating layer;
A method for manufacturing a separator for an electrochemical device, wherein the second polymer binder particle is one selected from a polyvinylidene-based binder, a polyolefin-based binder, and a combination thereof, wherein the content of hexafluoropropylene is less than 10 wt% based on the total weight of the polyvinylidene-based binder. In claim 14,
A method for manufacturing a separator for an electrochemical device, wherein the mixing step is performed for 1 hour or more and 3 hours or less. In claim 14,
The above first polymer binder is one selected from the group consisting of an acrylic binder; a polyvinylidene binder; a hybrid binder comprising an acrylic binder and a polyvinylidene binder; and a combination thereof.
A method for manufacturing a separator for an electrochemical device, wherein the difference between the temperature of the drying step and the glass transition temperature of the first polymer binder particles is 20°C or less.