Separator for electrochemical device and electrochemical device comprising same

Abstract

The present invention relates to a separator for an electrochemical device, in which an adhesive layer including a binder and a coagulant is formed on a coating layer. Due to the coagulant, the binder may be present in the adhesive layer in the form of secondary particles having a particle diameter of more than 1 μm but not more than 5 μm. As a result, the coverage of the adhesive layer with respect to the coating layer is low, and the separator of the present invention has low resistance and excellent electrolyte impregnation.

Description

Separator for electrochemical devices and electrochemical devices containing the same

[0001] This invention claims the benefit of Korean Patent Application No. 10-2024-0105160, filed with the Korean Intellectual Property Office on August 7, 2024, and Korean Patent Application No. 10-2025-0104415, filed with the Korean Intellectual Property Office on July 30, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same.

[0003] Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions. Recently, lithium secondary batteries have been widely used due to their high energy density and voltage, long cycle life, and wide range of applications.

[0004] Among the components of these electrochemical devices, the separator may include a polymer substrate having a porous structure located between the anode and cathode. The separator isolates the anode and cathode, preventing electrical short-circuiting between the two electrodes while simultaneously allowing electrolyte and ions to pass through. Although the separator itself does not participate in the electrochemical reaction, its physical properties, such as wettability with respect to the electrolyte, porosity, and thermal shrinkage, may affect the performance and safety of the electrochemical device.

[0005] Therefore, to enhance the physical properties of such membranes, various methods have been attempted, such as adding a coating layer to a porous polymer substrate and adding various substances to the coating layer to improve the properties of the coating layer. For example, inorganic substances may be added to the coating layer to enhance the mechanical strength of the membrane, or inorganic substances or hydrates may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate.

[0006] Within the above coating layer, inorganic particles can be linked to other inorganic particles by a polymer binder to form an interstitial volume, and lithium ions can move through the interstitial volume. That is, the coating layer including the polymer binder and inorganic particles serves to prevent thermal shrinkage of the separator while also assisting the movement of lithium ions through the separator.

[0007] Meanwhile, in order to secure adhesion between the electrode and the separator, an adhesive layer containing a binder may be additionally coated on the coating layer of the separator. In this case, when coating the adhesive layer by increasing the binder loading amount on the coating layer, the adhesion of the adhesive layer may be improved due to the high binder content, but the coverage of the adhesive layer on the coating layer may become excessively high, which may increase the resistance of the separator. In addition, in this case, the electrolyte impregnation property of the separator may also be reduced due to the binder having low electrolyte affinity compared to the inorganic particles, which may cause a problem of delay in the manufacturing process time of the separator and the electrochemical device.

[0008] Accordingly, there is a need to develop a novel separator for electrochemical devices that has excellent adhesion, low adhesive layer coverage on the surface of the coating layer, excellent electrolyte impregnation properties, and low resistance.

[0009] The present invention relates to a method for increasing the diameter (D) of binder secondary particles by a coagulant in an adhesive layer. 50 ) is more than 1 μm and less than 5 μm, the coverage of the adhesive layer on the coating layer is 5 to 80%, and accordingly, the resistance of the separator is low, and the purpose is to provide a separator for an electrochemical device.

[0010] In order to solve the above problem, the present invention comprises a porous polymer substrate, a coating layer disposed on at least one surface of the porous polymer substrate and including inorganic particles, and an adhesive layer disposed on the coating layer and including a binder and a coagulant, wherein the binder has an average diameter (D) of secondary particles. 50 ) is a particle-shaped binder having a particle size of more than 1 μm and less than or equal to 5 μm, the binder is a (co)polymer containing at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an amide group, and a carboxyl group, the coagulant is a (co)polymer containing at least one functional group selected from the group consisting of an amide group, an amino group, a hydroxyl group, and a carboxyl group, and the adhesive layer is distributed with a coverage corresponding to 5% or more and 80% or less of the surface area of ​​the coating layer.

[0011] The above binder has an average diameter of primary particles (D 50 ) may be a separator for electrochemical devices having a thickness of 1 μm or less.

[0012] The above coagulant may be a (co)polymer having a weight average molecular weight of 1,000 g / mol or more and 50,000 g / mol or less.

[0013] The weight ratio of the above binder and coagulant may be 1:0.1 or more and 1:1.5 or less.

[0014] The above adhesive layer may be distributed with a coverage corresponding to 40% or more and 70% or less of the surface area of ​​the above coating layer.

[0015] The above binder may be a (co)polymer comprising one or more monomers selected from the group consisting of vinyl alcohol, acrylic acid, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, dimethylaminoethyl methacrylate, acrylamide, glucose, and vinylamine.

[0016] The above coagulant may be a (co)polymer comprising one or more monomers selected from the group consisting of acrylamide, vinylamine, acrylic acid, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, dimethylaminoethyl methacrylate, glucose, and vinyl alcohol.

[0017] The thickness of the above adhesive layer may be 0.5 μm or more and 5 μm or less.

[0018] The thickness of the above coating layer may be 0.5 μm or more and 3 μm or less.

[0019] The present invention provides an electrochemical device comprising an anode, a cathode, and a separator for the electrochemical device, wherein the separator for the electrochemical device is interposed between the anode and the cathode.

[0020] In the separator for an electrochemical device according to the present invention, the binder in the adhesive layer exists in the form of secondary particles having a diameter of more than 1 μm and less than 5 μm, so that the adhesive layer coverage on the coating layer can be as low as 5 to 80%, and accordingly, the electrolyte impregnation property of the separator is excellent, and the movement of lithium ions through the separator is smooth, so that the resistance of the separator can also be low.

[0021] In addition, the method for manufacturing an electrochemical device according to the present invention has the advantage of being economical because it reduces the time required for the step of injecting and impregnating an electrolyte into an electrode assembly by using the separator having excellent impregnating properties.

[0022] Figure 1 (a) is a conceptual diagram of a separator for an electrochemical device of the present invention, and (b) is a conceptual diagram of a conventional separator for an electrochemical device in which an adhesive layer having only a binder without a coagulant is arranged.

[0023] Figure 2 is an image of the adhesive layer of the separator for the electrochemical device of Example 1, taken using the BSE (Backscattered Electron) mode of a scanning electron microscope. In the image, the gray area (A) represents the binder, the white area (B) represents the inorganic particles, and the black area (C) represents the pores.

[0024] Figure 3 is an image of the adhesive layer of the separator for an electrochemical device of Comparative Example 1, taken using the BSE (Backscattered Electron) mode of a scanning electron microscope. In the image, the gray area (A) represents the binder, the white area (B) represents the inorganic particles, and the black area (C) represents the pores.

[0025] Hereinafter, each component of the present invention will be described in more detail so that a person having ordinary skill in the art to which the present invention pertains can easily practice it; however, this is only an example, and the scope of the rights of the present invention is not limited by the following contents.

[0026] As used herein, the term "comprises" is used to list materials, compositions, devices, and methods useful in the present invention, but is not limited to the listed examples.

[0027] In this specification, the terms "about" and "substantially" are used to mean a range or approximation of a numerical value or degree, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting the disclosure, which mentions exact or absolute numerical values ​​provided to aid understanding of the present invention.

[0028] In this specification, when it is said that a component is “on”, this does not exclude other components being placed therebetween, unless otherwise specifically stated, but rather means that other components may be placed thereon.

[0029] In this specification, "electrochemical device" may refer to a primary battery, a secondary battery, a supercapacitor, or the like. More specifically, the electrochemical device may be a lithium ion secondary battery, and may be pouch-shaped, cylindrical, square, or coin-shaped, but the specific shape is not limited thereto.

[0030] In this specification, "electrode" refers to both "positive electrode" and "negative electrode," and may mean an electrode active material applied to at least one surface of a conductive material that does not cause a chemical change in an electrochemical device and dried. The types of the material and electrode active material are not limited as long as they can be used in an electrochemical device.

[0031] In this specification, the term "separator" may generally refer to a functional separator in which a porous coating layer containing an inorganic substance and a binder is formed on at least one surface of a porous polymer substrate such as a polyolefin substrate or a non-woven fabric, but in this specification, it may refer to a separator in which a coating layer containing an inorganic substance is formed on at least one surface of the porous polymer substrate, and an adhesive layer containing a binder is formed on the coating layer. In addition, the separator has a porous characteristic including a plurality of pores, and serves as a porous ion-conducting barrier that blocks electrical contact between a cathode and an anode in an electrochemical device while allowing ions to pass.

[0032] In this specification, the characteristic of having pores means that the object includes a plurality of pores and 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.

[0033] In this specification, "the average diameter of the particles (D 50 )" or “average particle size (D 50 )” means the diameter of the particle corresponding to the 50% point of the cumulative number of particles in the cumulative particle size distribution for the particles to be measured. The diameter can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to measure the difference in diffraction pattern according to particle size when the particles pass through the laser beam, thereby calculating the particle size distribution. By calculating the particle diameter at the point where the 50% of the cumulative number of particles according to the diameter in the measuring device is 50) can be measured. The diameters of the binder primary particles and secondary particles measured in this specification mean the average diameter measured in a slurry state in which each particle is mixed with a solvent.

[0034] In this specification, “coverage” means the ratio of a specific surface area covered by another material or layer. For example, the coverage of the adhesive layer with respect to the surface area of ​​the coating layer means the ratio of the area of ​​one side of the coating layer covered by the adhesive layer to the total area of ​​one side of the coating layer. The coverage can be measured by the following method. For each of five areas of one side of the separator coated with the adhesive layer, a scanning electron microscope image at a magnification of about 10 to 10,000 times is obtained, and the brightness of the binder included in the adhesive layer, the inorganic material included in the coating layer, the adhesive layer, or the pores present in the coating layer is distinguished using image analysis software. Then, the area occupied by each of the binder, the inorganic material, and the pores is calculated, and the coverage of the adhesive layer is measured by taking the average of the ratio (percentage) of the area where the binder is distributed compared to the total area.

[0035] In this specification, “particle-type binder” refers to a binder that maintains its particle-specific shape when dispersed in a solvent. In contrast, “solution-type binder” refers to a binder that loses its particle-specific shape and exists in a solution state when dispersed in a solvent.

[0036] As used herein, the term "primary particle" refers to an original particle from which another type of particle or a larger particle is formed. In relation to the binder of the present invention, the binder primary particle is a relatively small particle unit composed solely of a (co)polymer containing repeating units derived from monomers having hydroxyl groups, amino groups, amide groups, and carboxyl groups.

[0037] In this specification, “secondary particle” means a physically distinguishable particle separate from the primary particle, formed by combining, coagulating, or assembling a plurality of primary particles by a coagulant. In relation to the binder of the present invention, the binder secondary particle means a composite particle in which the coagulant and the binder primary particle are coagulated by intermolecular interactions such as hydrogen bonding, and the secondary particle is a particle having a volume approximately 5 times larger than the primary particle.

[0038] The "thickness" of the coating layer or adhesive layer in this specification can be measured using a known thickness measuring device. For example, the thickness of the coating layer or adhesive layer can be calculated by measuring the average value of the thickness using a commercially available thickness measuring device (Mitutoyo, VL-50S-B) with a 5 mm diameter tip.

[0039] Hereinafter, the present invention will be described in more detail.

[0040]

[0041] The present invention provides a separator for an electrochemical device.

[0042] According to one embodiment of the present invention, the separator for the electrochemical device comprises a porous polymer substrate, a coating layer disposed on at least one surface of the porous polymer substrate and including inorganic particles, and an adhesive layer disposed on the coating layer and including a binder and a coagulant, wherein the binder has an average diameter (D) of secondary particles. 50 ) is a particle-type binder having a particle size of more than 1 μm and less than or equal to 5 μm, wherein the binder is a (co)polymer containing at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an amide group, and a carboxyl group, and the coagulant is a (co)polymer containing at least one functional group selected from the group consisting of an amide group, an amino group, a hydroxyl group, and a carboxyl group, and the adhesive layer is characterized in that it is distributed with a coverage corresponding to 5% or more and 80% or less of the surface area of ​​the coating layer.

[0043]

[0044] The above electrochemical device separator may have a coating layer including the inorganic particles disposed on one or both surfaces of a porous polymer substrate, and an adhesive layer including the binder and a coagulant disposed on the other surface of the coating layer that is not in contact with the porous polymer substrate. In the case of the electrochemical device separator in which the coating layer is disposed on both surfaces of the porous polymer substrate, the adhesive layer may be disposed on the other surface of at least one coating layer. For example, in the case of the separator in which the coating layer is disposed on both surfaces of the porous polymer substrate, the adhesive layer may be disposed on the other surface of one of the coating layers, or the adhesive layers may be disposed on the other surfaces of each of the two coating layers. In addition, when the coating layer is disposed on one surface of the porous polymer substrate, the adhesive layer may be disposed on the other surface of the coating layer. The electrochemical device separator may have excellent heat resistance by minimizing the heat shrinkage problem of the porous polymer substrate by the coating layer, and at the same time, excellent adhesion between the separator and the electrode by the adhesive layer.

[0045]

[0046] In the separator for the electrochemical device, the binder is aggregated into a plurality of primary binder particles by the coagulant of the adhesive layer, and thus the binder has an average diameter (D 50) may exist in the form of secondary particles having a size of more than 1 μm and 5 μm. Therefore, the adhesive layer may have excellent adhesive strength but low coverage on the coating layer, and accordingly, within the adhesive layer having low coverage, lithium ions may move smoothly through the region where the binder does not exist, and thus the resistance of the separator may be low. Furthermore, unlike a conventional separator coated with an adhesive layer having high coverage, the electrolyte can easily penetrate into the coating layer and the porous polymer substrate through the region where the binder does not exist, and thus the electrolyte impregnation property of the separator may also be excellent. As can be seen in Fig. 1, in the separator for an electrochemical device according to an embodiment of the present invention, a plurality of binder primary particles in the adhesive layer may exist in the form of secondary particles aggregated by the coagulant, and as a result, the area of ​​the coating layer not covered by the adhesive layer may be large. Therefore, unlike the adhesive layer of a conventional electrochemical device separator having high adhesive layer coverage due to the absence of a coagulant in the adhesive layer, the electrochemical device separator of the present invention may have low adhesive layer coverage on the coating layer.

[0047]

[0048] Referring to FIG. 2, in the adhesive layer of Example 1, it can be seen that the binder is aggregated into the form of secondary particles by the coagulant, and thus the inorganic particles (white area, B) and pores (black area, C) of the coating layer are exposed in a portion corresponding to about 40% of the total area of ​​the coating layer that is not covered with the binder (gray area, A). On the other hand, referring to FIG. 3, in the adhesive layer of Comparative Example 1, since no coagulant is present, it can be seen that the binder primary particles evenly cover about 90% of the total area of ​​the coating layer. That is, it can be seen that the adhesive layer coverage is low in the separator for an electrochemical device of the present invention.

[0049]

[0050] The above binder has an average diameter of secondary particles (D50 ) is a particle-type binder having an average diameter of secondary particles of more than 1 μm and less than or equal to 5 μm. Specifically, the binder may have an average diameter of secondary particles of more than 1 μm, 1.5 μm or more, 2 μm or more, 2.5 μm or more, or 3 μm or more, and may also have an average diameter of 5 μm or less, 4.5 μm or less, 4 μm or less, 3.5 μm or less, or 3 μm or less. The average diameter of secondary particles of the binder (D 50 ) satisfies the above range, a relatively small number of secondary particles may exist within the adhesive layer of the same area. Accordingly, since the secondary particles of the binder are sparsely distributed on the coating layer, the coverage of the adhesive layer for the coating layer may be low, about 5 to 80%. The average diameter (D) of the binder secondary particles 50 ) is less than 1 μm outside the above range, the size of the secondary particles is small, so that a large number of secondary particles can be uniformly distributed within the same area of ​​the adhesive layer. Accordingly, the secondary particles of the binder can be densely packed on the coating layer, and as a result, the area where the binder does not exist on the coating layer is considerably small, so that the coverage of the adhesive layer can be high. Therefore, in this case, the resistance of the separator may be high, and the electrolyte impregnation property may also be poor. In addition, when the diameter of the binder secondary particles exceeds 5 μm outside the above range, the thickness of the separator may become excessively thick, and thus the electrode volume may be relatively reduced within the limited cell volume. Therefore, as a result, the energy density of the electrochemical device including the separator may be reduced.

[0051]

[0052] The binder may be a particle-shaped (co)polymer. Accordingly, when the primary particles of the binder aggregate to form secondary particles, the particle uniformity of the secondary particles may be improved, thereby enhancing the adhesion to the electrode of the separator. In addition, since the binder maintains a particle shape, sufficient space may exist between the binder particles, and lithium ions may effectively move through the space.

[0053]

[0054] The above coagulant may be a soluble (co)polymer. When the above coagulant is a soluble (co)polymer, the coagulant penetrates into the binder while dissolved in a solvent, so that hydrogen bonding between the functional group of the above-described coagulant and the functional group of the binder can be effectively formed, thereby obtaining binder secondary particles having a secondary particle diameter within the above range.

[0055]

[0056] The binder is a polymer or copolymer containing at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an amide group, and a carboxyl group, and the coagulant is a polymer or copolymer containing at least one functional group selected from the group consisting of an amide group, an amino group, a hydroxyl group, and a carboxyl group. Therefore, a functional group such as a hydroxyl group contained in the binder and a functional group such as an amide group contained in the coagulant may hydrogen bond to cause the binder to coagulate in the form of secondary particles having a particle diameter of the size described above. Furthermore, when the binder and the coagulant are used together, the degree of hydrogen bonding between the binder and the coagulant varies depending on the content of the coagulant, and thus, there is an advantage in that it is easy to finely control the coverage of the adhesive layer. Specifically, the binder may be a polymer or copolymer containing a hydroxyl group, and the coagulant may be a polymer or copolymer containing an amide group.

[0057]

[0058] The adhesive layer is distributed with a coverage corresponding to 5% or more and 80% or less of the surface area of ​​the coating layer. Specifically, the coverage of the adhesive layer may be 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more, and may also be 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less. More specifically, the adhesive layer may be distributed with a coverage corresponding to 40% or more and 70% or less of the surface area of ​​the coating layer. When the coverage of the adhesive layer satisfies the above range, the adhesive strength of the adhesive layer is excellent, and at the same time, there is a sufficient area on the surface of the coating layer that is not covered by the binder, through which lithium ions can move smoothly, and thus the resistance of the separator can be low. Furthermore, since the electrolyte can easily penetrate into the coating layer and the porous polymer substrate through the area where the binder does not exist, the electrolyte impregnation property of the separator can also be excellent. In contrast, if the coverage of the adhesive layer is high beyond the above range, the amount of lithium ions penetrating the coating layer and the adhesive layer can significantly decrease, and thus the resistance of the separator can be high. In addition, since the binder has low electrolyte affinity, if the adhesive layer coverage is excessively high, the electrolyte impregnation property of the separator can also be significantly reduced due to the binder. In addition, if the coverage of the adhesive layer is low below the above range, the binder content in the adhesive layer can be excessively low, and the adhesion between the separator and the electrode can be poor.

[0059]

[0060] According to one embodiment of the present invention, the binder has an average diameter (D) of the primary particles 50) may be 1 μm or less. Specifically, the primary particles of the binder may have an average diameter of 1 μm or less, 0.9 μm or less, 0.8 μm or less, 0.6 μm or less, 0.4 μm or less, or 0.2 μm or less, and may also have a diameter of 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, or 250 nm or more. When the primary particle diameter of the binder satisfies the above range, the size of the secondary particles of the binder aggregated by combining with the coagulant may satisfy the above-described range. Furthermore, the primary particles of the binder have excellent dispersibility, so that the movement of lithium ions through the adhesive layer can be smooth, and the thickness of the adhesive layer can also be maintained thin.

[0061]

[0062] According to one embodiment of the present invention, the coagulant may be a (co)polymer having a weight average molecular weight of 1,000 g / mol or more and 50,000 g / mol or less. Specifically, the weight average molecular weight of the coagulant (co)polymer may be 1,000 g / mol or more, 3,000 g / mol or more, 5,000 g / mol or more, or 10,000 g / mol or more, and may also be 50,000 g / mol or less, 30,000 g / mol or less, 10,000 g / mol or less, or 5,000 g / mol or less. When the weight average molecular weight of the coagulant (co)polymer satisfies the above range, the coagulant contains a sufficient number of amide groups, amino groups, hydroxyl groups, or carboxyl groups, so that hydrogen bonding with the binder can be effectively formed, and as a result, it is easy to obtain binder secondary particles having the above-described particle diameter. In addition, when the weight average molecular weight of the coagulant satisfies the above range, the viscosity of the adhesive layer slurry containing the coagulant is low, so that the adhesive layer can be easily coated on the coating layer, and thus, there is an advantage in that the formation of an adhesive layer with the target coverage is easy.

[0063]

[0064] According to one embodiment of the present invention, the weight ratio of the binder and the coagulant may be 1:0.1 or more and 1:1.5 or less. Specifically, the weight ratio of the binder and the coagulant may be 1:0.1 or more, 1:0.2 or more, 1:0.3 or more, 1:0.4 or more, 1:0.5 or more, 1:0.6 or more, 1:0.7 or more, 1:0.8 or more, 1:0.9 or more, or 1:1 or more, and further may be 1:1.5 or less, 1:1.3 or less, 1:1.1 or less, 1:0.9 or less, 1:0.7 or less, or 1:0.5 or less. When the weight ratio of the binder and the coagulant satisfies the above range, the binder can be coagulated in the form of secondary particles having a particle diameter in the above-described range, and thus, an adhesive layer having low coverage can be disposed on the coating layer. Furthermore, when the weight ratio of the binder and coagulant satisfies the above range, the peel strength of the adhesive layer can be improved, and the resistance of the separator can also be reduced.

[0065]

[0066] According to one embodiment of the present invention, the binder may be a (co)polymer comprising one or more monomers selected from the group consisting of vinyl alcohol, acrylic acid, 2-hydroxyethyl (meth)acrylate methacrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, dimethylaminoethyl methacrylate, acrylamide, glucose, and vinylamine. When the binder (co)polymer comprises the monomers listed above, functional groups such as a hydroxyl group, an amino group, an amide group, or a carboxyl group included in the binder easily form hydrogen bonds with functional groups of the above-described coagulant, so that the binder can easily coagulate into secondary particles having a particle diameter in the above-described range. For example, when the binder is polyacrylic acid (PAA) containing acrylic acid as a monomer, the hydroxyl group of the binder can hydrogen bond with the functional group of the coagulant, so that binder secondary particles having a particle diameter in the above-described range can be easily obtained.

[0067]

[0068] According to one embodiment of the present invention, the coagulant may be a (co)polymer comprising one or more monomers selected from the group consisting of acrylamide, vinylamine, dimethylaminoethyl methacrylate, acrylic acid, 2-hydroxyethyl (meth)acrylate methacrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, glucose, and vinyl alcohol. When the coagulant (co)polymer comprises the monomers listed above, functional groups such as an amide group, an amino group, a hydroxyl group, or a carboxyl group contained in the coagulant easily form hydrogen bonds with functional groups of the above-described binder, so that the binder can easily be coagulated into secondary particles having a particle diameter in the above-described range. For example, when the coagulant is polyacrylamide (PAM) containing acrylamide as a monomer, the amide group of the coagulant can easily form hydrogen bonds with the functional group of the binder to obtain binder secondary particles having a particle diameter in the above-described range.

[0069]

[0070] According to one embodiment of the present invention, the thickness of the adhesive layer may be 0.5 μm or more and 5 μm or less. Specifically, the thickness of the adhesive layer may be 0.5 μm or more, 1 μm or more, 1.5 μm or more, or 2 μm or more, and may also be 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. When the thickness of the adhesive layer satisfies the above range, the adhesion of the separator to the electrode is excellent, and the resistance of the separator can also be low because the overall thickness of the separator is not significantly increased. Furthermore, when the thickness of the adhesive layer satisfies the above range, the electrolyte impregnation property of the separator can also be excellent.

[0071]

[0072] According to one embodiment of the present invention, the thickness of the coating layer may be 0.5 μm or more and 3 μm or less. Specifically, the thickness of the coating layer may be 0.5 μm or more, 1 μm or more, 1.5 μm or more, or 2 μm or more, and further, 3 μm or less, 2.5 μm or less, or 2 μm or less. When the thickness of the coating layer satisfies the above range, the insulation and thermal stability of the separator can be increased, and at the same time, the overall thickness of the separator is also reduced, so that the volume of the electrochemical device can be minimized. As a result, the amount of active material included in the electrochemical device can be increased, and thus the energy density of the electrochemical device can be increased.

[0073]

[0074] According to one embodiment of the present invention, the thickness of the separator for an electrochemical device may be 10 μm or more and 30 μm or less. Specifically, the thickness of the separator for an electrochemical device may be 10 μm or more, 12 μm or more, 14 μm or more, 16 μm or more, 18 μm or more, or 20 μm or more, and further may be 30 μm or less, 27 μm or less, 25 μm or less, 23 μm or less, 21 μm or less, 20 μm or less, or 18 μm or less. When the thickness of the separator for an electrochemical device satisfies the above range, the separator can electrically insulate the positive and negative electrodes while minimizing the volume of the electrochemical device. As a result, the amount of active material included in the electrochemical device can be increased, and thus the energy density of the electrochemical device can be increased.

[0075]

[0076] According to one embodiment of the present invention, the inorganic particles have an operating voltage range of the electrochemical device (e.g., Li / Li +It may be that no oxidation and / or reduction reaction occurs at 0 V to 5 V as a reference. Specifically, the inorganic particles are BaTiO3, Pb(Zr,Ti)O3(PZT), b 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, 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), and antimony pentoxide (Sb2O5).

[0077]

[0078] According to one embodiment of the present invention, the average diameter (D) of the inorganic particles 50 ) may be 0.3 μm or more and 1 μm or less. Specifically, the average diameter (D) of the inorganic particles 50 ) may be 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more, and may also be 1 μm or less, 0.8 μm or less, or 0.6 μm or less. When the average diameter of the inorganic particles satisfies the above range, the dispersibility of the inorganic particles in the coating layer slurry is excellent, so that a coating layer of uniform thickness can be formed.

[0079]

[0080] According to one embodiment of the present invention, the coating layer may further include, in addition to the inorganic particles, a second binder for stably fixing the inorganic particles by connecting them together. The second binder may be the same as or different from the binder included in the adhesive layer, and examples thereof include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, poly(ethylene-co-vinyl acetate), polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, It may be at least one selected from the group consisting of cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene butadiene copolymer, polyimide, and styrene-butadiene rubber.

[0081]

[0082] According to one embodiment of the present invention, the weight ratio of the inorganic particles and the second binder (inorganic particles: second binder) may be 50:50 to 99:1, specifically 70:30 to 95:5. When the content ratio of the inorganic particles to the second binder satisfies the above numerical range, the thermal safety improvement performance of the separator may be improved, and the pore size and porosity may be increased due to an increase in the empty space formed between the inorganic particles, thereby improving the performance of the final battery.

[0083]

[0084] According to one embodiment of the present invention, the porous polymer substrate may be a porous membrane having a plurality of pores formed therein, which electrically insulates the positive and negative electrodes to prevent short circuits. For example, when the electrochemical device is a lithium secondary battery, the porous polymer substrate may be an ion-conductive barrier that blocks electrical contact between the positive and negative electrodes while allowing lithium ions to pass through. At least a portion of the pores may form a three-dimensional network that connects the surface and the interior of the porous polymer substrate, and a fluid may pass through the porous polymer substrate through the pores.

[0085]

[0086] The porous polymer substrate may use a material that is physically and chemically stable with respect to the organic solvent electrolyte. For example, the porous polymer substrate may include, but is not limited to, a resin such as a polyolefin-based resin such as polyethylene, polypropylene, and polybutylene, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof. A polyolefin-based resin is preferably used. A polyolefin-based resin is suitable for manufacturing an electrochemical device with a higher energy density because it can be processed into a relatively thin thickness and the application of a coating slurry is easy.

[0087]

[0088] The porous polymer substrate may have a single-layer or multi-layer structure. The porous polymer substrate may include two or more polymer resin layers having different melting points (Tm), thereby providing a shutdown function in the event of a high-temperature runaway of the battery. For example, the porous polymer substrate may include a polypropylene layer having a relatively high melting point and a polyethylene layer having a relatively low melting point. Preferably, the porous polymer substrate may have a three-layer structure in which polypropylene, polyethylene, and polypropylene are laminated in that order. The polyethylene layer melts when the temperature of the battery rises above a predetermined temperature, thereby shutting down the pores, thereby preventing thermal runaway of the battery.

[0089]

[0090] According to one embodiment of the present invention, the thickness of the porous polymer substrate may be 4 μm or more and 15 μm or less. Specifically, the thickness of the porous polymer substrate may be 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, or 10 μm or more, and may also be 15 μm or less, 13 μm or less, 11 μm or less, 9 μm or less, or 7 μm or less. By controlling the thickness of the porous polymer substrate within the above-described range, the volume of the electrochemical device can be minimized while electrically insulating the positive and negative electrodes, thereby increasing the amount of active material included in the electrochemical device.

[0091]

[0092] According to one embodiment of the present invention, the porous polymer substrate may include pores having an average diameter of 0.01 μm or more and 1 μm or less. Specifically, the size of the pores included in the porous polymer substrate may be 0.01 μm or more, 0.02 μm or more, 0.03 μm or more, or 0.04 μm or more, and may also be 1 μm or less, 0.09 μm or less, 0.08 μm or less, 0.07 μm or less, or 0.06 μm or less. Preferably, the size of the pores may be 0.02 μm or more and 0.06 μm or less. By controlling the pore size of the porous polymer substrate within the above-described range, the air permeability and ionic conductivity of the entire manufactured membrane can be controlled.

[0093]

[0094] The porous polymer substrate may have a permeability of 10 s / 100cc or more and 100 s / 100cc or less. Specifically, the permeability of the porous polymer substrate may be 10 s / 100cc or more and 90 s / 100cc or less, 20 s / 100cc or more and 80 s / 100cc or less, 30 s / 100cc or more and 70 s / 100cc or less, or 40 s / 100cc or more and 60 s / 100cc or less. Preferably, the permeability of the porous polymer substrate may be 50 s / 100cc or more and 70 s / 100cc or less. When the permeability of the porous polymer substrate is within the above-described range, the permeability of the manufactured separator may be provided within a range suitable for securing the output and cycle characteristics of the electrochemical device. The above air permeability (s / 100cc) means the time (in seconds) it takes for 100cc of air to pass through a porous polymer substrate or membrane of a predetermined area under a constant pressure. The above air permeability can be measured using an air permeability tester (Gurley densometer) according to ASTM D 726-58, ASTM D726-94 or JIS-P8117. For example, using Gurley's 4110N equipment, air at a pressure of 0.304kPa or 1.215 kN / m 2 100 cc of air under the pressure of water occupies 1 square inch (or 6.54 cm 2 ) can be used to measure the time it takes for 100 cc of air to pass through a 1-square-inch sample under a constant pressure of 4.8 inches of water at room temperature. For example, using the Asahi Seiko EG01-55-1MR equipment, the time it takes for 100 cc of air to pass through a 1-square-inch sample can be measured.

[0095]

[0096] The porous polymer substrate may have a porosity of 10 vol% or more and 60 vol% or less. Specifically, the porosity of the porous polymer substrate may be 10 vol% or more, 20 vol% or more, 30 vol% or more, 40 vol% or more, or 50 vol% or more, and may also be 60 vol% or less, 50 vol% or less, or 40 vol% or less. Preferably, the porosity of the porous polymer substrate may be 30 vol% or more and 50 vol% or less. When the porosity of the porous polymer substrate is in the above-described range, the ionic conductivity of the manufactured separator can be provided in a range suitable for securing the output and cycle characteristics of the electrochemical device. The porosity refers to the volume ratio of pores to the total volume of the porous polymer substrate. The porosity can be measured by a method known in the art. For example, it can be measured by the BET (Brunauer Emmett Teller) measurement method using the adsorption of nitrogen gas, the capillary flow porometer, and the water or mercury intrusion method.

[0097]

[0098] The present invention provides a method for manufacturing an electrochemical device.

[0099] The method for manufacturing the electrochemical device may include a method for manufacturing the separator for the electrochemical device. In the separator for the electrochemical device and the method for manufacturing the electrochemical device according to one embodiment of the present invention, any description overlapping with the description of the separator for the electrochemical device will be omitted.

[0100] According to one embodiment of the present invention, the method for manufacturing the electrochemical device includes a step (S10) of forming a coating layer by applying a coating layer slurry containing inorganic particles to at least one surface of a porous polymer substrate, a step (S20) of forming an adhesive layer by applying an adhesive layer slurry containing a binder and a coagulant on the coating layer, a step (S30) of manufacturing an electrode assembly by interposing a separator for an electrochemical device manufactured through the step S20 between a positive electrode and a negative electrode, and a step (S40) of housing the electrode assembly in a battery case and then injecting and impregnating a liquid electrolyte into the battery case, wherein the binder has a diameter (D) of a secondary particle. 50 ) is a particle-shaped binder having a particle size of more than 1 μm and less than or equal to 5 μm, and is a (co)polymer containing at least one functional group selected from the group consisting of a hydroxyl group, an amino group, an amide group, and a carboxyl group, and the coagulant may be a (co)polymer containing at least one functional group selected from the group consisting of an amide group, an amino group, a hydroxyl group, and a carboxyl group.

[0101]

[0102] Specifically, the steps (S10) and (S20) may be steps for manufacturing the separator for the electrochemical device, and the step (S10) may be a step for forming a coating layer on at least one surface of a porous polymer substrate in the step for manufacturing the separator for the electrochemical device. The step (S20) may be a step for forming an adhesive layer on the coating layer. The separator for the electrochemical device of the present invention described above may be manufactured through the steps (S10) and (S20).

[0103]

[0104] Specifically, the method for forming a coating layer or an adhesive layer in the steps (S10) and (S20) 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, bar coating, or a mixture thereof can be used. For example, the method for forming a coating layer in the step (S10) may be to apply the coating layer slurry on a porous polymer substrate using gravure coating or slot die coating and then dry it, and the method for forming an adhesive layer in the step (S20) may be to apply the adhesive layer slurry on a coating layer using gravure coating or slot die coating and then dry it.

[0105]

[0106] The above step (S30) may be a step of manufacturing an electrode assembly by interposing the separator for the electrochemical device of the present invention manufactured through the above steps (S10) and (S20) between the cathode and the anode. The cathode and the anode may be as follows.

[0107]

[0108] According to one embodiment of the present invention, the positive electrode may have 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 may be a layered compound such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-xLithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn1-xM x A lithium manganese composite oxide represented by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0109]

[0110] According to one embodiment of the present invention, the negative electrode may have 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 may include carbon such as lithium metal oxide, non-graphitizable carbon, and graphite carbon as the negative electrode active material; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함하는 것일 수 있다.

[0111]

[0112] 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 powders, conductive whiskers, conductive metal oxides, activated carbon, and polyphenylene derivatives, or a mixture of two or more conductive materials thereof. More specifically, the conductive material may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more conductive materials thereof.

[0113] 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.

[0114]

[0115] 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, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples thereof include, but are not limited to, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0116]

[0117] According to one embodiment of the present invention, the positive electrode slurry for manufacturing 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).

[0118]

[0119] 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.

[0120]

[0121] According to one embodiment of the present invention, the negative electrode slurry for manufacturing 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 Corporation).

[0122]

[0123] 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.

[0124]

[0125] The above step (S40) may be a step of housing the electrode assembly in a battery case, and then injecting a liquid electrolyte into the battery case to impregnate the electrode and separator with the electrolyte. The above step (S40) has the advantage of requiring less time for impregnation compared to impregnating an electrode assembly including a separator with a high coverage of a conventional adhesive layer by using the separator for an electrochemical device of the present invention described above. Therefore, the method for manufacturing an electrochemical device of the present invention has the advantage of being economical because it requires less time for the entire manufacturing process of a conventional manufacturing method.

[0126]

[0127] According to one embodiment of the present invention, the electrolyte is A + B - As a salt with the same structure as A + is Li + , Na + , K + B containing an ion composed of an alkali metal cation or a combination thereof; - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as or combinations thereof are dissolved or dissociated in organic solvents such as 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 or mixtures thereof, but are not limited thereto.

[0128]

[0129] The present invention provides an electrochemical device.

[0130] The electrochemical device may include the electrochemical device separator of the present invention described above, and may be manufactured using the electrochemical device manufacturing method described above. In the electrochemical device according to one embodiment of the present invention, any descriptions that overlap with the descriptions of the electrochemical device separator and the electrochemical device manufacturing method will be omitted.

[0131]

[0132] According to one embodiment of the present invention, the electrochemical device includes a positive electrode, a negative electrode, and a separator for an electrochemical device of the present invention, and the separator for an electrochemical device may be interposed between the positive electrode and the negative electrode. Since the electrochemical device of the present invention includes the separator for an electrochemical device of the present invention described above, the electrolyte impregnation property of the separator is improved, and the resistance of the separator is also lowered, so that the battery performance of the electrochemical device can be excellent.

[0133]

[0134] The above electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept encompassing primary batteries and secondary batteries. The secondary battery can be charged and discharged, 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.

[0135]

[0136] One embodiment of the present invention may provide 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; 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.

[0137]

[0138] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0139]

[0140] Examples and comparative examples.

[0141] Manufacturing of separators for electrochemical devices

[0142] <Example 1>

[0143] Polyethylene resin (weight average molecular weight 900,000 g / mol) was extruded and a porous polymer substrate (total thickness of approximately 9 μm, porosity of 40 vol%) was manufactured using a wet method.

[0144] As inorganic particles, the average particle diameter (D) is 600 nm. 50) was prepared. As a second binder used in the coating layer, a particle-type polyacrylic acid binder was prepared, and as a dispersant, sodium carboxymethyl cellulose (CMC-Na) was prepared. The prepared inorganic particles, the second binder, and the dispersant were added to water in a weight ratio of 92:5:3, and then the inorganic particles were crushed and dispersed to prepare a coating layer slurry. The coating layer slurry was applied to both surfaces of the porous polymer substrate by bar coating using a doctor blade, and dried with air at 50°C using a heat gun to form a coating layer on both surfaces of the porous polymer substrate.

[0145] To form an adhesive layer, a particle-shaped polyacrylic acid (average diameter of primary particles (D)) is used as a binder. 50 ) 250 nm) 4g was prepared, and 1g of soluble polyacrylamide (weight average molecular weight 5,000 g / mol) was prepared as a coagulant. The binder and coagulant were added and dispersed in 95g of water as a solvent at a weight ratio of 1:0.25 to prepare an adhesive layer slurry. At this time, the diameter (D of the coagulated binder secondary particles) 50 ) was 2 μm.

[0146] The above adhesive layer slurry was applied to the surface of one of the two coating layers by bar coating using a coating layer doctor blade, and dried with air at 50°C using a heat gun to form an adhesive layer on the coating layer. The above process was performed in the same manner on the other coating layer so that an adhesive layer was formed on both sides of the porous polymer substrate, thereby manufacturing a separator for an electrochemical device.

[0147] <Example 2>

[0148] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as Example 1, except that 4 g of binder and 2 g of coagulant were used when manufacturing the adhesive layer slurry.

[0149] <Example 3>

[0150] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as Example 1, except that 4 g of binder and 4 g of coagulant were used when manufacturing the adhesive layer slurry.

[0151] <Example 4>

[0152] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as in Example 1, except that particulate polyvinyl alcohol was used as a binder when manufacturing the adhesive layer slurry.

[0153] <Example 5>

[0154] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as in Example 1, except that soluble polyvinylamine (weight average molecular weight: 5,000 g / mol) was used as a coagulant when manufacturing the adhesive layer slurry.

[0155] <Comparative Example 1>

[0156] In the above Example 1, a separator for an electrochemical device was manufactured in the same manner as Example 1, except that the adhesive layer slurry was manufactured without using a coagulant.

[0157] <Comparative Example 2>

[0158] In the above Example 1, polyvinylidene fluoride (diameter of primary particles (D)) was used as a binder when preparing the adhesive layer slurry. 50 ) 250 nm) and polyacrylamide (weight average molecular weight 5,000 g / mol) as a coagulant was added and dispersed in water as a solvent at a weight ratio of 1:0.25 to prepare an adhesive layer slurry, and a separator for an electrochemical device was manufactured in the same manner as in Example 1, except that the adhesive layer slurry was manufactured.

[0159]

[0160]

[0161] <Measurement of resistance of the separator>

[0162] Coin cells were manufactured by sandwiching the electrochemical device separators of the above examples and comparative examples between SUS. An electrolyte containing 1 M LiPF6 and a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 1:2 was injected into the coin cells. In order to measure the resistance of the coin cells, the resistance was measured through electrochemical impedance spectroscopy using VMP3 from BioLogic Science Instrument at 25°C under the conditions of an amplitude of 10 mV and a scan range of 0.1 Hz to 1 MHz, and the results are shown in Tables 1 and 2 below.

[0163]

[0164] <Measuring the coverage of the adhesive layer>

[0165] A scanning electron microscope (SEM, BSE mode) image at 1,000x magnification was obtained for each of five different areas on one side of the adhesive layer-coated separator. From these, the binder included in the adhesive layer, the inorganic material included in the coating layer, and the brightness of the pores existing in the adhesive layer and the coating layer were distinguished using image analysis software, and then the binder, inorganic material, and pores were distinguished. Then, the area occupied by each of the binder, inorganic material, and pores was calculated, and the coverage of the adhesive layer was measured by averaging the ratio (percentage) of the area where the binder was distributed to the total area. Figures 2 and 3 below are images of the adhesive layers of Example 1 and Comparative Example 1, respectively, taken with a scanning electron microscope (SEM, BSE mode). The gray area (A) is the binder included in the adhesive layer, and the white area (B) and black area (C) are the inorganic particles and pores included in the coating layer, respectively. Therefore, the ratio of the gray area to the total area was measured using image analysis software to calculate the coverage of the adhesive layer for the coating layer. In the case of Example 1, the adhesive layer coverage according to the calculation method was 61%, and in the case of Comparative Example 1, the adhesive layer coverage was 90%.

[0166]

[0167] ClassificationExample 1Example 2Example 3Example 4Example 5Coating layer thickness (μm)2 / 22 / 22 / 22 / 22 / 2Adhesive layerBinder / coagulantPAA / PAMPAA / PAMPAA / PAMPVA / PAMPAA / PVAmBinder primary particle diameter (nm)250250250300250Binder secondary particle diameter (μm)23545Weight ratio of binder and coagulant1:0.251:0.51:11:0.251:0.25Thickness (μm)2 / 23 / 35 / 54 / 45 / 5Coverage (%)6152234628Separator thickness (μm)1719232123Electrical resistance (Ω)0.80.70.40.60.5

[0168]

[0169] Classification Comparison Example 1 Comparison Example 2 Coating layer thickness (μm) 2 / 2 2 / 2 Adhesive layer Binder / coagulant PAA / -PVDF / PAMBinder primary particle diameter (nm) 250 250 Binder secondary particle diameter (μm) 0.51 Weight ratio of binder and coagulant - 1:0.25 Thickness (μm) 0.5 / 0.5 1 / 1 Coverage (%) 90 85 Membrane thickness (μm) 14 15 Electrical resistance (Ω) 1.2 1.0

[0170]

[0171] Manufacturing of electrode assemblies

[0172] Using the separator for the electrochemical device of the above examples and comparative examples, a cathode assembly and an electrode assembly were manufactured, respectively.

[0173] 1) Manufacturing of the anode

[0174] Cathode active material (LiNi) 0.8 Mn 0.1 Co 0.1O2), conductive agent (carbon black), dispersant (N-methylpyrrolidone, ADC-01, LG Chemical), and binder resin (PVDF-HFP and PVDF mixture) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a cathode active material layer with a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied to 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).

[0175] 2) Manufacturing of cathode

[0176] 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 with a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to manufacture an anode having an anode active material layer (thickness 120 μm).

[0177] 3) Lamination process

[0178] The above-mentioned cathode and anode were each cut into a size of 5 cm × 5 cm and prepared, and the separator and PET film of the examples and comparative examples were cut into a size of 10 cm × 10 cm and prepared. Then, the cathode / separator / PET film were laminated and then hot pressed for 1 second under the conditions of 60°C and 6.5 MPa to manufacture the cathode assembly, and the cathode / separator / PET film were laminated and then laminated in the same manner to obtain the cathode assembly. In the cathode assembly and the anode assembly, the ends of the PET film and the separator in each assembly were sealed with imide tape so that the electrolyte did not penetrate between the PET film and the separator, but only between the electrode and the separator interface.

[0179]

[0180] <Measuring the time required for electrolyte impregnation>

[0181] The positive electrode assembly that underwent the above lamination process was immersed in a bath containing 10 mL of an electrolyte containing 1 M LiPF6 and a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 1:2 to conduct an impregnation evaluation. The negative electrode assembly was also subjected to an impregnation evaluation in the same manner. Since the separator becomes transparent when impregnated with the electrolyte, the time required for the entire separator to be impregnated is indicated as the electrolyte impregnation time in Table 3 below.

[0182]

[0183] Classification Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Anode assembly electrolyte impregnation time (min) 311542067142 Cathode assembly electrolyte impregnation time (min) 1461934023

[0184]

[0185] As shown in Tables 1 and 2 above, it can be confirmed that the binder and coagulant in the adhesive layer of the separator of the embodiment are hydrogen-bonded, so that the diameter of the binder secondary particles is more than 1 μm and less than or equal to 5 μm, and thus the adhesive layer coverage on the coating layer satisfies 5 to 80%. On the other hand, it can be confirmed that the separator of Comparative Example 1, which does not include a coagulant in the adhesive layer, and the separator of Comparative Example 2, in which the binder does not include a functional group such as a hydroxyl group, a carboxyl group, an amide group, or an amino group even when the adhesive layer includes a coagulant, and thus no hydrogen bonding occurs, both have binder secondary particles in the adhesive layer of less than or equal to 1 μm, and thus the adhesive layer coverage on the coating layer exceeds 80%.

[0186]

[0187] As a result, it can be confirmed that the separators of Examples 1 to 5 have low adhesive layer coverage, so that lithium ions can move smoothly through the adhesive layer, and thus the electrical resistance of the separators is low, less than 1 Ω, while the separators of Comparative Examples 1 and 2 have high adhesive layer coverage, so that the electrical resistance of the separators is high, more than 1 Ω.

[0188]

[0189] In addition, as shown in Table 3 above, in the positive electrode assembly and negative electrode assembly including the separator of the example, the adhesive layer coverage of the separator was low, so that the electrolyte could flow smoothly through the pores of the adhesive layer, and as a result, the time for the separator to be impregnated with the electrolyte was short. On the other hand, in the separator of the comparative example, the adhesive layer coverage was high, so that the electrolyte could not flow smoothly through the pores of the adhesive layer, and as a result, the time for the separator to be impregnated with the electrolyte was long. That is, through this, it can be confirmed that the electrolyte impregnation property of the separator is excellent in the electrode assembly including the separator of the example.

[0190]

[0191] In summary, compared to conventional separators, the separator of the present invention has the advantage of low adhesive layer coverage, low electrical resistance due to the separator, and excellent electrolyte impregnation properties.

[0192]

[0193] [Explanation of symbols]

[0194] 1: Binder 2: Inorganic particles

[0195] 10: Porous polymer substrate 20: Coating layer

[0196] 30: Adhesive layer A: Binder

[0197] B: Inorganic particles C: Pores

Claims

1. Porous polymer substrate; A coating layer disposed on at least one surface of the porous polymer substrate and including inorganic particles; and An adhesive layer disposed on the coating layer and including a binder and a coagulant, The above binder has an average diameter of secondary particles (D 50 ) is a particle-shaped binder having a size of 1 μm or more and 5 μm or less, The above binder is a (co)polymer containing one or more functional groups selected from the group consisting of a hydroxyl group, an amino group, an amide group, and a carboxyl group, The above coagulant is a (co)polymer containing at least one functional group selected from the group consisting of an amide group, an amino group, a hydroxyl group, and a carboxyl group, A separator for an electrochemical device, wherein the adhesive layer is distributed with a coverage corresponding to 5% to 80% of the surface area of ​​the coating layer.

2. In paragraph 1, The above binder has an average diameter of primary particles (D 50 ) A separator for an electrochemical device having a thickness of 1 μm or less.

3. In paragraph 1, A separator for an electrochemical device, wherein the above coagulant is a (co)polymer having a weight average molecular weight of 1,000 g / mol or more and 50,000 g / mol or less.

4. In paragraph 1, A separator for an electrochemical device, wherein the weight ratio of the binder and the coagulant is 1:0.1 or more and 1:1.5 or less.

5. In paragraph 1, A separator for an electrochemical device, wherein the adhesive layer is distributed with a coverage corresponding to 40% or more and 70% or less of the surface area of ​​the coating layer.

6. In paragraph 1, A separator for an electrochemical device, wherein the binder is a (co)polymer comprising at least one monomer selected from the group consisting of vinyl alcohol, acrylic acid, 2-hydroxyethyl (meth)acrylate methacrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, dimethylaminoethyl methacrylate, acrylamide, glucose, and vinylamine.

7. In paragraph 1, A separator for an electrochemical device, wherein the coagulant is a (co)polymer containing one or more monomers selected from the group consisting of acrylamide, vinylamine, acrylic acid, 2-hydroxyethyl (meth)acrylate methacrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, dimethylaminoethyl methacrylate, glucose, and vinyl alcohol.

8. In paragraph 1, A separator for an electrochemical device, wherein the thickness of the adhesive layer is 0.5 μm or more and 5 μm or less.

9. In paragraph 1, A separator for an electrochemical device, wherein the thickness of the coating layer is 0.5 μm or more and 3 μm or less.

10. A positive electrode; a negative electrode; and a separator for an electrochemical device according to any one of claims 1 to 9, An electrochemical device wherein the separator for the electrochemical device is interposed between the anode and the cathode.

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