Separator for electrochemical device and electrochemical device including the same

Abstract

The present invention relates to a separator for an electrochemical device and an electrochemical device including the same, and more particularly, to a separator for an electrochemical device that can increase the capture effect of transition metal ions generated at a positive electrode and prevent by-products that accumulate on the interface of the positive electrode from clogging pores by varying the content of inorganic particles contained in a porous polymer substrate depending on the position, and an electrochemical device including the separator.

Description

[Technical Field]

[0001] The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2023-0052684, filed with the Korean Intellectual Property Office on April 21, 2023, the entire contents of which are incorporated herein by reference. The present invention relates to a separator for an electrochemical device and an electrochemical device including the same, and more particularly, to a separator for an electrochemical device that increases the capture effect of transition metal ions generated at a positive electrode by varying the content of inorganic particles contained in a porous polymer substrate depending on the position, and that can prevent by-products that accumulate on the interface of the positive electrode from clogging the pores, and an electrochemical device including the same. [Background technology]

[0002] Among the components of an electrochemical device, the separator is disposed between the positive and negative electrodes and contains a polymer matrix with a porous structure. It serves to separate the positive and negative electrodes, prevent electrical shorts between the two electrodes, and allow electrolytes and ions to pass through. Although the separator itself does not participate in the electrochemical reaction, its physical properties, such as wettability with the electrolyte, degree of porosity, and thermal shrinkage, affect the performance and safety of the electrochemical device.

[0003] Therefore, various methods have been attempted to add a coating layer to a porous polymer substrate to enhance the physical properties of the separator, and to modify the physical 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 improve the mechanical strength of the separator, or an inorganic substance or hydrate may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0004] The separator may be attached to the electrode through a lamination process, and a binder resin may be added to the coating layer composition of the separator to ensure adhesion between the electrode and the separator.

[0005] On the other hand, in lithium-ion secondary batteries, when transition metal ions in the positive electrode material are eluted, they pass through the separation membrane and accumulate in the negative electrode, causing the problem of battery degradation due to the accumulated transition metal ions.

[0006] Furthermore, if these transition metal ions and by-products accumulate in the pores of the porous polymer substrate contained in the separator, the pores of the coating layer, and the interface between the porous polymer substrate and the coating layer, the battery performance will rapidly deteriorate, resulting in battery degradation.

[0007] Therefore, there has been a demand for the development of a battery that can prevent transition metal ions generated in the positive electrode material from migrating to the negative electrode and prevent pores from being blocked by the transition metal ions. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a separator for an electrochemical device, which has different pore sizes, porosities, and inorganic particle contents depending on the position of a porous polymer substrate, and which allows the inorganic particles to absorb transition metal ions generated at a positive electrode, thereby preventing pore clogging by the transition metal ions and reducing by-products that may be generated during battery operation, and an electrochemical device including the separator.

[0009] 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 following description. [Means for solving the problem]

[0010] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate containing inorganic particles, a first portion adjacent to one side of the porous polymer substrate, and a second portion opposite the first portion, wherein the weight of the inorganic particles contained in the first portion is greater than the weight of the inorganic particles contained in the second portion, and the inorganic particles are capable of adsorbing transition metal ions.

[0011] According to one embodiment of the present invention, the inorganic particles may be one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic composite (MOF), and combinations thereof.

[0012] According to one embodiment of the present invention, the inorganic particles contained in the first portion and the inorganic particles contained in the second portion may be the same or different.

[0013] According to one embodiment of the present invention, the porous polymer substrate may be a polyolefin resin.

[0014] According to one embodiment of the present invention, the size of the pores contained in the first portion may be larger than the size of the pores contained in the second portion.

[0015] According to one embodiment of the present invention, the size of the pores contained in the first portion may be 20 μm or more and 100 μm or less, and the size of the pores contained in the second portion may be 20 μm or more and 100 μm or less.

[0016] According to one embodiment of the present invention, the porosity of the first portion may be greater than the porosity of the second portion.

[0017] According to one embodiment of the present invention, the porosity of the first portion may be 50% by volume or more and 70% by volume or less, and the porosity of the second portion may be 40% by volume or more and 50% by volume or less.

[0018] According to one embodiment of the present invention, the thickness of the first portion may be the same as or smaller than the thickness of the second portion.

[0019] According to one embodiment of the present invention, the first portion may be provided adjacent to the positive electrode.

[0020] According to one embodiment of the present invention, a portion of the surface of the inorganic particle may be provided to protrude outward from the porous polymer substrate.

[0021] According to one embodiment of the present invention, the separator for an electrochemical device may have a thickness of 9 μm or less.

[0022] One embodiment of the present invention provides an electrochemical device comprising: a positive electrode; a negative electrode; and a separator; wherein the separator is a separator for the electrochemical device interposed between the positive electrode and the negative electrode.

[0023] According to one embodiment of the present invention, a first portion of the separator may be disposed to face the positive electrode, and a second portion of the separator may be disposed to face the negative electrode. [Effects of the Invention]

[0024] A separator for an electrochemical device according to an embodiment of the present invention can capture transition metal ions generated at a positive electrode and prevent them from accumulating at a negative electrode.

[0025] A separator for an electrochemical device according to an embodiment of the present invention can prevent pores from being blocked by transition metal ions generated at a positive electrode, thereby preventing deterioration of the battery.

[0026] The separator for an electrochemical device according to one embodiment of the present invention has small pores and can ensure insulation.

[0027] An electrochemical device according to an embodiment of the present invention can improve the performance of a battery and extend the life of the battery. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram of a separator for an electrochemical element according to one embodiment of the present invention. [Figure 2] 1 is a schematic view of a separator for an electrochemical element according to one embodiment of the present invention. [Figure 3] 1 is a schematic diagram of an electrochemical device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] In this specification, when a part is said to "comprise" a certain component, this does not mean that it excludes other components, but that it may further include other components, unless specifically stated to the contrary.

[0030] In this specification, "A and / or B" means "A and B, or A or B."

[0031] In this specification, when something is said to be provided "on" a certain component, this does not exclude other components being disposed therebetween, but means that other components may be further disposed thereon, unless otherwise specified.

[0032] As used herein, the term "porosity" means that an object contains a plurality of pores, and the pores are interconnected to allow gas and / or liquid fluids to pass from one side of the object to the other side.

[0033] In this specification, the term "separator" refers to a porous membrane having a large number of pores, which acts as a porous ion-conducting barrier that allows ions to pass through while blocking electrical contact between the negative electrode and the positive electrode in an electrochemical device.

[0034] The present invention will be described in further detail below.

[0035] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate containing inorganic particles, a first portion adjacent to one side of the porous polymer substrate, and a second portion opposite the first portion, wherein the weight of the inorganic particles contained in the first portion is greater than the weight of the inorganic particles contained in the second portion, and the inorganic particles are capable of adsorbing transition metal ions.

[0036] The separator for an electrochemical device according to an embodiment of the present invention can capture transition metal ions generated at the positive electrode and prevent their accumulation at the negative electrode. Furthermore, the separator for an electrochemical device according to an embodiment of the present invention can prevent pores from being blocked by transition metal ions generated at the positive electrode, thereby preventing battery deterioration. Furthermore, the separator for an electrochemical device according to an embodiment of the present invention has small pores, ensuring insulation properties.

[0037] 1 is a schematic view of a separator for an electrochemical device according to one embodiment of the present invention, and the separator for an electrochemical device according to one embodiment of the present invention will be described in detail with reference to FIG.

[0038] According to one embodiment of the present invention, the separator 100 for an electrochemical device includes a porous polymer substrate 110. As described above, the separator 100 for an electrochemical device includes the porous polymer substrate 110, which allows lithium ions to pass through while blocking electrical contact, and can implement a shutdown function at an appropriate temperature.

[0039] According to one embodiment of the present invention, the porous polymer substrate may be a polyolefin-based resin. Specifically, the porous polymer substrate 110 may be manufactured using a polyolefin-based resin as a base resin. Examples of polyolefin-based resins include polyethylene, polypropylene, and polypentene, and the porous polymer substrate 110 may include one or more of these. A porous separator having a large number of pores manufactured using such a polyolefin-based resin as a base resin is advantageous in that it can provide a shutdown function at an appropriate temperature.

[0040] According to one embodiment of the present invention, the weight-average molecular weight of the polyolefin resin may be from 500,000 to 1,500,000. Adjusting the weight-average molecular weight of the polyolefin resin within the above range can improve the compression resistance of the separator. Furthermore, when a mixture of different polyolefin resins is used or a separator membrane is formed with a multi-layer structure made of different polyolefin resins, the weight-average molecular weight of the polyolefin resin can be calculated by adding the weight-average molecular weights of the respective polyolefin resins according to their content ratio.

[0041] In this specification, the "weight average molecular weight (Mw)" can be measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies), and the measurement conditions can be set as follows.

[0042] Column: PL Olexis (Polymer Laboratories) -Solvent: TCB (Trichlorobenzene) -Flow rate: 1.0ml / min -Sample concentration: 1.0mg / ml -Injection volume: 200μl -Column temperature: 160℃ -Detector: Agilent High Temperature RI detector -Standard: Polystyrene (corrected by a cubic function)

[0043] 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 kneaded with a plasticizer (diluents) and inorganic particles at a high temperature to form a single phase, and then the polyolefin resin and the plasticizer are phase-separated during a cooling process, and the plasticizer is extracted to form pores, followed by stretching and heat setting.

[0044] According to one embodiment of the present invention, the porous polymer substrate 110 may be manufactured by a method (wet method) in which a first portion of the porous polymer substrate is formed by kneading a polyolefin resin with a plasticizer (diluents) and inorganic particles at a high temperature to form a single phase, phase-separating the polyolefin resin and the plasticizer during a cooling process, extracting the plasticizer to form pores, and then stretching and heat-setting the resulting mixture; and a second portion of the porous polymer substrate is manufactured by a method (wet method) in which a polyolefin resin is kneaded with a plasticizer (diluents) and inorganic particles at a high temperature to form a single phase, phase-separating the polyolefin resin and the plasticizer during a cooling process, extracting the plasticizer to form pores, and then stretching and heat-setting the resulting mixture; and then thermally laminating the first portion and the second portion.

[0045] According to one embodiment of the present invention, the average pore size and maximum pore size of the separator 100 for an electrochemical device can be easily prepared by a person skilled in the art to meet the scope of the present invention by adjusting the mixing ratio of the plasticizer, the stretching ratio, the heat setting temperature, etc.

[0046] In this specification, "pore size" can be calculated from the pore size distribution measured using a capillary flow porometer. For example, a separation membrane to be measured is first wetted with a wetting agent such as Galwick solution, and then air pressure is gradually increased on one side of the substrate. When the applied air pressure exceeds the capillary attraction of the wetting agent present in the pores, the wetting agent blocking the pores is expelled. The pore size and distribution can be measured based on the pressure and flow rate at the moment of expulsion, and the average pore size and maximum size can be determined from this.

[0047] According to one embodiment of the present invention, the separator 100 for an electrochemical device includes a porous polymer substrate 110 containing inorganic particles. As described above, the separator for an electrochemical device includes a porous polymer substrate containing inorganic particles, which can improve the efficiency of capturing transition metal ions generated at the positive electrode and prevent the transition metal ions from passing through pores and accumulating in the negative electrode or at the interface between the separator and the positive electrode.

[0048] According to one embodiment of the present invention, the porous polymer substrate includes a first portion 111 adjacent to one side of the porous polymer substrate and a second portion 113 facing the first portion 111. Specifically, the porous polymer substrate may include a first portion including the one side and a second portion including the other side, respectively. That is, the porous polymer substrate may include a first portion including one side of the porous substrate and a second portion including the other side of the porous substrate, based on the center line of the porous polymer substrate. The first portion and the second portion may be in contact with each other, or another portion may be further included between the first portion and the second portion. As described above, by including the first portion adjacent to one side of the porous polymer substrate and the second portion facing the first portion, the physical or chemical properties of the electrodes adjacent to one side and the other side of the porous polymer substrate may be different, thereby improving battery performance.

[0049] According to one embodiment of the present invention, the weight of the inorganic particles contained in the first portion may be greater than the weight of the inorganic particles contained in the second portion. Specifically, the content of the inorganic particles in the first portion may be greater than the content of the inorganic particles in the second portion. As described above, by making the weight of the inorganic particles contained in the first portion greater than the weight of the inorganic particles contained in the second portion, transition metal ions generated at the positive electrode can be easily adsorbed, improving the capture efficiency.

[0050] According to one embodiment of the present invention, the particle size of the inorganic particles contained in the first portion may be larger than the particle size of the inorganic particles contained in the second portion. As described above, by making the particle size of the inorganic particles contained in the first portion larger than the particle size of the inorganic particles contained in the second portion, the size and / or porosity of the pores in the first portion can be made larger than the size and / or porosity of the pores in the second portion.

[0051] According to one embodiment of the present invention, the inorganic particles can adsorb transition metal ions. Specifically, the transition metal ions can be transition metal ions generated at the positive electrode. As described above, by selecting the inorganic particles from those capable of adsorbing transition metal ions, the transition metal ions generated at the positive electrode can be adsorbed and collected, thereby minimizing the accumulation of transition metal ions at the negative electrode.

[0052] According to one embodiment of the present invention, the inorganic particles may be one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic composite (MOF), and combinations thereof. By selecting the inorganic particles from the above, it is possible to adsorb and capture transition metal ions generated at the positive electrode and minimize the accumulation of transition metal ions at the negative electrode.

[0053] According to one embodiment of the present invention, the porous carbon may be one selected from the group consisting of activated carbon, activated carbon fiber, carbon nanotubes, and combinations thereof.

[0054] According to one embodiment of the present invention, the porous metal oxide may be one selected from the group consisting of porous SiO, porous AlO, porous AlOOH, porous Al(OH), and combinations thereof.

[0055] According to one embodiment of the present invention, the metal-organic complex (MOF) may be one selected from the group consisting of MOF-808, UiO-66-NH2, UiO-66, UiO-66-COOH, UiO-66-F4, UiO-67, MIL-101, MIL-125, MIL-53, MIL-100, MIL-53(Al)MOF, ZIF-8 MOF, HKUST-1 MOF, and combinations thereof.

[0056] According to one embodiment of the present invention, the inorganic particles contained in the first portion and the inorganic particles contained in the second portion may be the same or different. As described above, by making the inorganic particles contained in the first portion and the inorganic particles contained in the second portion the same or different, it is possible to realize different transition metal ion capture efficiencies depending on the position and adjust the porosity and pore size depending on the position.

[0057] According to one embodiment of the present invention, the size of the pores in the first portion may be larger than the size of the pores in the second portion. As described above, by adjusting the size of the pores in the first portion to be larger than the size of the pores in the second portion, it is possible to prevent the pores from being blocked by transition metal ions generated in the positive electrode, and to reduce the size of the pores in the portion where there is no risk of pore blocking, thereby ensuring insulation and reducing the thickness of the separator.

[0058] According to one embodiment of the present invention, the size of the pores contained in the first portion may be 20 μm or more and 100 μm or less. Specifically, the size of the pores contained in the first portion may be 25 μm or more and 95 μm or less, 30 μm or more and 90 μm or less, 35 μm or more and 85 μm or less, 40 μm or more and 80 μm or less, 45 μm or more and 75 μm or less, 50 μm or more and 70 μm or less, or 55 μm or more and 65 μm or less. By adjusting the size of the pores contained in the first portion within the above range, it is possible to prevent the pores from being blocked by transition metal ions generated in the positive electrode.

[0059] According to one embodiment of the present invention, the size of the pores in the second portion may be 20 μm to 100 μm. Specifically, the size of the pores in the second portion may be 25 μm to 95 μm, 30 μm to 90 μm, 35 μm to 85 μm, 40 μm to 80 μm, 45 μm to 75 μm, 50 μm to 70 μm, or 55 μm to 65 μm. By adjusting the size of the pores in the second portion within the above range, the size of the pores in the portion where there is no risk of pore clogging can be reduced, thereby ensuring insulation and thereby reducing the thickness of the separator.

[0060] According to one embodiment of the present invention, the porosity of the first portion may be greater than the porosity of the second portion. As described above, by making the porosity of the first portion greater than the porosity of the second portion, pore blockage due to transition metal ions generated in the positive electrode can be prevented, and the porosity of the portion where there is no risk of pore blockage can be reduced, thereby ensuring insulation and reducing the thickness of the separator.

[0061] According to one embodiment of the present invention, the porosity of the first portion may be 50 vol% to 70 vol%. Specifically, the porosity of the first portion may be 51 vol% to 69 vol%, 52 vol% to 68 vol%, 53 vol% to 67 vol%, 54 vol% to 66 vol%, 55 vol% to 65 vol%, 56 vol% to 64 vol%, 57 vol% to 63 vol%, 58 vol% to 62 vol%, or 59 vol% to 61 vol%. Adjusting the porosity of the first portion within the above range can prevent pore blockage by transition metal ions generated in the positive electrode.

[0062] According to one embodiment of the present invention, the porosity of the second portion may be 40 vol% to 50 vol%. Specifically, the porosity of the second portion may be 41 vol% to 49 vol%, 42 vol% to 48 vol%, 43 vol% to 47 vol%, or 44 vol% to 46 vol%. By adjusting the porosity of the second portion within the above range, the size of the pores in the portion where there is no risk of pore clogging can be reduced, thereby ensuring insulation and reducing the thickness of the separator.

[0063] As used herein, "porosity" refers to the ratio of the volume occupied by pores to the total volume, and is expressed in units of vol%. It can be used interchangeably with terms such as void ratio and porosity. In the present invention, the measurement of porosity is not particularly limited, and in one embodiment of the present invention, it can be measured, for example, by Brunauer-Emmett-Teller (BET) measurement using nitrogen gas or mercury penetration (Hg porosimeter). Alternatively, in one embodiment of the present invention, the true density of the electrode active material layer can be calculated from the density (apparent density) of the obtained electrode (electrode active material layer), the composition ratio of the materials contained in the electrode (electrode active material layer), and the density of each component, and the porosity of the electrode active material layer can be calculated from the difference between the apparent density and the true density (net density).

[0064] According to one embodiment of the present invention, the thickness of the first portion may be the same as or smaller than the thickness of the second portion. The thickness of each portion may refer to the length of a line perpendicular to one surface of the porous polymer substrate relative to the total length passing through the porous polymer substrate. Specifically, the thickness of the first portion may be greater than 0% and less than or equal to 50% of the total thickness of the porous polymer substrate. As described above, by making the thickness of the first portion the same as or smaller than the thickness of the second portion, it is possible to prevent pores from being blocked by transition metal ions generated in the positive electrode and ensure the insulation properties of the separator.

[0065] According to one embodiment of the present invention, the first portion may be provided adjacent to the positive electrode. As described above, providing the first portion adjacent to the positive electrode prevents transition metal ions and / or by-products generated at the positive electrode from accumulating in the porous polymer substrate, the coating layer (described below), and the interface between the coating layer and the porous polymer substrate, thereby improving the efficiency of capturing transition metal ions and preventing battery degradation. Furthermore, blocking of pores in the first portion by transition metal ions generated at the positive electrode can be prevented, thereby improving the battery life.

[0066] According to one embodiment of the present invention, a portion of the surface of the inorganic particle may be provided to protrude outward from the porous polymer substrate. Specifically, this may mean that the inorganic particle is not enclosed by the porous polymer substrate, and a portion of the inorganic particle is exposed to the pores of the porous polymer substrate or the surface of the porous polymer substrate. As described above, by providing a portion of the surface of the inorganic particle to protrude outward from the porous polymer substrate, the efficiency of the capture of transition metal ions by the inorganic particle can be improved.

[0067] According to one embodiment of the present invention, the separator for an electrochemical device may have a thickness of 9 μm or less. Specifically, the thickness of the separator for an electrochemical device may be greater than 0 μm and less than 9 μm, 1 μm to 8 μm, 2 μm to 7 μm, 3 μm to 6 μm, or 4 μm to 5 μm. By adjusting the thickness of the separator for an electrochemical device within the above range, the energy density of the electrochemical device can be improved.

[0068] In one embodiment of the present invention, the thickness of the porous polymer substrate, the coating layer, and / or the adhesive layer may be measured using a contact-type thickness gauge, such as Mitutoyo's VL-50S-B.

[0069] According to one embodiment of the present invention, the separator 100 for an electrochemical device may include a coating layer 130 provided on at least one surface of the porous polymer substrate 110. Specifically, the separator 100 for an electrochemical device may include a coating layer 130 provided on one surface of the porous polymer substrate 110, or may include a coating layer 130 provided on both surfaces of the porous polymer substrate 110. As described above, the separator 100 for an electrochemical device may include a coating layer 130 provided on at least one surface of the porous polymer substrate 110, thereby improving the heat resistance and mechanical properties of the separator and preventing electrical short circuits of electrodes due to separator shrinkage at high temperatures.

[0070] According to one embodiment of the present invention, the separator 100 for an electrochemical device may include a coating layer 130 including a first polymer binder 131 (not shown) and inorganic particles 133 (not shown). As described above, the coating layer 130 includes the first polymer binder 131 and the inorganic particles 133, which improves the heat resistance and mechanical properties of the separator, prevents electrical short circuits of electrodes due to separator shrinkage at high temperatures, and allows pores to be formed inside the coating layer.

[0071] According to one embodiment of the present invention, the coating layer 130 may be formed by binding inorganic particles 133 with a first polymer binder 131 and accumulating them on the coating layer 130 side. Pores within the coating layer 130 may be due to interstitial volumes, which are empty spaces between the inorganic particles 133.

[0072] According to one embodiment of the present invention, the coating layer includes a plurality of pores, i.e., the coating layer may be porous.

[0073] According to one embodiment of the present invention, the first polymer binder 131 may be an acrylic binder, a polyvinylidene binder, or a combination thereof. As described above, by selecting the first polymer binder 131 from the above, the heat resistance of the coating layer can be improved and the bonding strength of the inorganic particles in the coating layer can be improved.

[0074] According to one embodiment of the present invention, the first polymer binder 131 may be an acrylic binder, which can maintain the porosity of the separator, improve the adhesive strength between the electrode and the separator during the lamination process of the battery, improve the ease of battery fabrication, and enable a stable stacking process.

[0075] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and is preferably a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0076] According to one embodiment of the present invention, the (meth)acrylic acid ester is selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, and (meth)acrylic acid esters. Examples of suitable acrylates include decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the acrylate may be one or more selected from these. Among these, the acrylate may be one or more selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, with methyl (meth)acrylate being particularly preferred.

[0077] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be one or more selected from the group consisting of styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate-based polymers, and more particularly, may be an acrylate-containing copolymer.

[0078] According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder 131 may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting a polyvinylidene fluoride-based binder as the polyvinylidene-based binder, the resistance of the separator can be reduced.

[0079] According to one embodiment of the present invention, the polyvinylidene-based binder included in the first polymer binder 131 may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting a polyvinylidene fluoride-based binder as the polyvinylidene-based binder, the resistance of the separator can be reduced.

[0080] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder from the copolymer of polyvinylidene fluoride and hexafluoropropylene, dissolution of the polymer binder by the electrolyte can be minimized.

[0081] According to one embodiment of the present invention, the polyvinylidene-based binder contained in the first polymer binder 131 may have a hexafluoropropylene content of 10 wt% or more. Specifically, the polyvinylidene-based binder contained in the first polymer binder 131 may have a hexafluoropropylene content of 10 wt% to 80 wt%, 15 wt% to 75 wt%, 20 wt% to 70 wt%, 25 wt% to 65 wt%, 30 wt% to 60 wt%, 35 wt% to 55 wt%, or 40 wt% to 50 wt%. By adjusting the hexafluoropropylene content of the polyvinylidene-based binder in the first polymer binder 131 within the above range, the resistance of the separator can be reduced.

[0082] According to one embodiment of the present invention, the first polymer binder 131 may be a hybrid binder particle including an acrylic binder and a polyvinylidene binder. As described above, by selecting the first polymer binder 131 from the hybrid binder particles including an acrylic binder and a polyvinylidene binder, adhesive strength with the electrode can be improved.

[0083] According to one embodiment of the present invention, the first polymer binder 131 may be in a particulate or liquid form. By selecting the first polymer binder 131 from the above, it is possible to adjust the porosity and air permeability of the coating layer, adjust the pore size of the coating layer, and improve the mechanical properties of the coating layer.

[0084] According to one embodiment of the present invention, the content of the first polymer binder 131 may be 30 parts by weight or less, based on 100 parts by weight of the coating layer. Specifically, the content of the first polymer binder 131 may be greater than 0 parts by weight and less than 30 parts by weight, 5 parts by weight to 25 parts by weight, 10 parts by weight to 20 parts by weight, 12 parts by weight to 18 parts by weight, or 13 parts by weight to 16 parts by weight, based on 100 parts by weight of the coating layer 130. By adjusting the content of the first polymer binder 131 within the above range, the mechanical properties of the coating layer 130 can be improved, the porosity of the coating layer can be maintained, and the heat resistance can be improved.

[0085] According to one embodiment of the present invention, the content of the inorganic particles 133 may be 70 parts by weight or more relative to 100 parts by weight of the coating layer 130. Specifically, the content of the inorganic particles 133 may be more than 70 parts by weight but less than 100 parts by weight, 75 parts by weight to 95 parts by weight, 80 parts by weight to 90 parts by weight, 82 parts by weight to 88 parts by weight, or 84 parts by weight to 86 parts by weight relative to 100 parts by weight of the coating layer 130. By adjusting the content of the inorganic particles 133 within the above ranges, the heat resistance and mechanical properties of the separator can be improved.

[0086] According to one embodiment of the present invention, the inorganic particles 133 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 those that can be used within the operating voltage range (e.g., Li / Li) of the applied electrochemical device. + There are no particular limitations on the material, as long as it does not undergo oxidation and / or reduction reactions at a voltage (0 V to 5 V relative to the reference voltage).

[0087] According to one embodiment of the present invention, non-limiting examples of the inorganic particles 133 include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg1 / 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), antimony pentoxide (Sb2O5), zeolite-based compounds, and the like can be included, and one or more of these can be included.

[0088] According to one embodiment of the present invention, the zeolite-based compound may be one selected from the group consisting of zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11, and combinations thereof. The zeolite-based compound may have a high specific surface area. By selecting a zeolite-based compound from the above, the ability to adsorb gases and transition metals can be improved.

[0089] According to one embodiment of the present invention, the average diameter (D 50 Although there are no particular limitations on the thickness of the coating layer, it is preferably in the range of 0.3 μm to 1 μm in order to form a coating layer of uniform thickness and to have an appropriate porosity. Specifically, if it is less than 0.3 μm, the dispersibility of inorganic particles in the slurry prepared for producing the coating layer may decrease, and if it exceeds 1 μm, the thickness of the coating layer formed may increase.

[0090] As used herein, the term "D50 particle size" refers to the particle size at 50% of the cumulative distribution of particle numbers according to particle size. The particle size can be measured using a 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 analyzer (e.g., Microtrac S3500). The particle size distribution is calculated by measuring the difference in the diffraction pattern according to particle size as the particles pass through a laser beam. The D50 particle size can be measured by calculating the particle diameter at 50% of the cumulative distribution of particle numbers according to particle size measured by the analyzer.

[0091] 2 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention, and the separator for an electrochemical device according to one embodiment of the present invention will be described in detail with reference to FIG.

[0092] According to one embodiment of the present invention, the separator 100 for an electrochemical device may include an adhesive layer 150 provided on the coating layer 130. Specifically, the separator 100 for an electrochemical device may include an adhesive layer 150 provided on the coating layer 130 and including a second polymer binder 151 (not shown). As described above, since the separator 100 for an electrochemical device includes the adhesive layer 150 provided on the coating layer 130, adhesive strength between the electrode and the separator can be ensured during lamination of the separator with the electrode.

[0093] According to one embodiment of the present invention, the thickness of the coating layer 130 on any one side of the porous polymer substrate 110 may be 2.0 μm or less. Specifically, the thickness of the coating layer 130 may be greater than 0 μm and less than 2.0 μm, 0.1 μm to 1.9 μm, 0.2 μm to 1.8 μm, 0.3 μm to 1.7 μm, 0.4 μm to 1.6 μm, 0.5 μm to 1.5 μm, 0.6 μm to 1.4 μm, 0.7 μm to 1.3 μm, 0.8 μm to 1.2 μm, or 0.9 μm to 1.1 μm. Adjusting the thickness of the coating layer 130 within the above ranges can improve the heat resistance of the separator and increase the energy density of the separator.

[0094] According to one embodiment of the present invention, the second polymer binder 151 may be an acrylic binder, a polyvinylidene binder, or a combination thereof. As described above, by selecting the second polymer binder 151 from the above, the adhesiveness of the adhesive layer can be improved.

[0095] According to one embodiment of the present invention, the second polymer binder 151 may be an acrylic binder, which can maintain the porosity of the separator, improve the adhesive strength between the electrodes and the separator during the lamination process of the battery, improve the ease of battery fabrication, and enable a stable stacking process.

[0096] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and is preferably a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0097] According to one embodiment of the present invention, the (meth)acrylic acid ester is selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, and (meth)acrylic acid esters. Examples of suitable acrylates include decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the acrylate may be one or more selected from these. Among these, the acrylate may be one or more selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, with methyl (meth)acrylate being particularly preferred.

[0098] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be one or more selected from the group consisting of styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate-based polymers, and more particularly, may be an acrylate-containing copolymer.

[0099] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder 151 may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting a polyvinylidene fluoride-based binder as the polyvinylidene-based binder, the resistance of the separator can be reduced.

[0100] According to one embodiment of the present invention, the polyvinylidene-based binder included in the second polymer binder 151 may be a polyvinylidene difluoride (PVdF)-based binder. As described above, by selecting a polyvinylidene fluoride-based binder as the polyvinylidene-based binder, the resistance of the separator can be reduced.

[0101] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder from the copolymer of polyvinylidene fluoride and hexafluoropropylene, dissolution of the polymer binder by the electrolyte can be minimized.

[0102] According to one embodiment of the present invention, the polyvinylidene-based binder contained in the second polymer binder 151 may have a hexafluoropropylene content of 10 wt% or more. Specifically, the polyvinylidene-based binder contained in the first polymer binder 131 may have a hexafluoropropylene content of 10 wt% to 80 wt%, 15 wt% to 75 wt%, 20 wt% to 70 wt%, 25 wt% to 65 wt%, 30 wt% to 60 wt%, 35 wt% to 55 wt%, or 40 wt% to 50 wt%. By adjusting the hexafluoropropylene content of the polyvinylidene-based binder in the first polymer binder 131 within the above range, the resistance of the separator can be reduced. The content of the hexafluoropropylene (HFP) monomer is 1 H-NMR and / or 19 It can be measured by F-NMR.

[0103] According to one embodiment of the present invention, the second polymer binder 151 may be a hybrid binder particle including an acrylic binder and a polyvinylidene binder. As described above, by selecting the second polymer binder 151 from the hybrid binder particles including an acrylic binder and a polyvinylidene binder, adhesive strength with the electrode can be improved.

[0104] According to one embodiment of the present invention, the second polymer binder 151 may be in a particulate or liquid form. By selecting the second polymer binder 151 from the above, it is possible to adjust the porosity and air permeability of the adhesive layer, adjust the size of the pores in the adhesive layer, and improve the adhesive strength of the adhesive layer.

[0105] According to one embodiment of the present invention, the particle size (D50) of the second polymer binder is preferably in the range of 0.3 μm to 1 μm. Specifically, if it is less than 0.3 μm, the dispersibility of the second polymer binder in the slurry prepared for manufacturing the adhesive layer may be reduced, and if it is more than 1 μm, the thickness of the formed adhesive layer may be increased.

[0106] According to one embodiment of the present invention, the thickness of the adhesive layer 150 may be 2.0 μm or less. Specifically, the thickness of the adhesive layer 150 may be greater than 0 μm and less than 2.0 μm, greater than 0.1 μm and less than 1.9 μm, greater than 0.2 μm and less than 1.8 μm, greater than 0.3 μm and less than 1.7 μm, greater than 0.4 μm and less than 1.6 μm, greater than 0.5 μm and less than 1.5 μm, greater than 0.6 μm and less than 1.4 μm, greater than 0.7 μm and less than 1.3 μm, greater than 0.8 μm and less than 1.2 μm, or greater than 0.9 μm and less than 1.1 μm. Adjusting the thickness of the adhesive layer 150 within the above ranges can improve the adhesion of the separator to the electrodes and increase the energy density of the separator.

[0107] In this specification, the "air permeability of the separation membrane" is determined by the The measurement may be performed using a Seico EG01-55-1MR device.

[0108] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, the method including: kneading a mixture containing a polyolefin resin, inorganic particles, and a plasticizer at a high temperature; extruding the kneaded mixture; cooling the extruded mixture to phase-separate the plasticizer; extracting the plasticizer to form pores; and stretching and heat-setting the pore-formed mixture to manufacture a porous polymer substrate.

[0109] The method for manufacturing an electrochemical device according to an embodiment of the present invention can easily prevent an increase in the resistance of the separator and form a thin separator, thereby improving the energy density of the battery. In the method for manufacturing a separator for an electrochemical device according to an embodiment of the present invention, details that overlap with the description of the separator for an electrochemical device will be omitted.

[0110] According to one embodiment of the present invention, there is provided a method for manufacturing a separator for an electrochemical device, comprising: applying a slurry for a coating layer, which includes a first polymer binder 131 and inorganic particles 133, onto at least one surface of the porous polymer substrate 110; and applying a slurry for an adhesive layer, which includes a second polymer binder 151.

[0111] According to one embodiment of the present invention, the method for manufacturing an electrochemical device includes a step of applying a coating layer slurry, including a first polymer binder 131 and inorganic particles 133, onto at least one surface of a porous polymer substrate 110. As described above, by applying the coating layer slurry onto at least one surface of the porous polymer substrate, a coating layer can be formed in a single application, and the content of inorganic particles in the coating layer slurry is excessive, which improves the heat resistance of the separator and allows the solvent to evaporate easily.

[0112] According to one embodiment of the present invention, prior to applying the slurry for the coating layer, a polymer solution may be prepared by dissolving the first polymer binder in a suitable solvent. The solvent preferably has a solubility index similar to that of the binder polymer and a low boiling point. This facilitates uniform mixing and subsequent solvent removal. Non-limiting examples of solvents that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0113] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a first polymer binder may be dispersed in a suitable dispersing medium to prepare a polymer emulsion, thereby providing the slurry. The dispersing medium preferably has a low boiling point, which facilitates uniform mixing and subsequent removal of the dispersing medium. Non-limiting examples of dispersing mediums that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof.

[0114] According to one embodiment of the present invention, inorganic particles may be added and dispersed in the polymer emulsion or polymer solution. The content ratio of the inorganic particles to the polymer binder particles is as described above and may be appropriately adjusted in consideration of the thickness, pore size, and porosity of the final coating layer according to one embodiment of the present invention.

[0115] According to one embodiment of the present invention, the solid content of the coating layer slurry may be 10 wt% to 30 wt%. Specifically, the solid content of the coating layer slurry may be 11 wt% to 29 wt%, 12 wt% to 28 wt%, 13 wt% to 27 wt%, 14 wt% to 26 wt%, 15 wt% to 25 wt%, 16 wt% to 24 wt%, 17 wt% to 23 wt%, 18 wt% to 22 wt%, or 19 wt% to 21 wt%. By adjusting the solid content of the coating layer slurry within the above range, an increase in the resistance of the separator can be prevented, and the separator can be formed into a thin film, thereby improving the energy density of the battery.

[0116] According to one embodiment of the present invention, the method for applying the coating layer slurry to the surface of the porous polymer substrate 110 is not limited to any particular method, and any conventional method known in the art may be used, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0117] According to one embodiment of the present invention, the method for manufacturing an electrochemical device includes a step of applying a slurry for an adhesive layer including a second polymer binder 151. As described above, by including a step of applying a slurry for an adhesive layer including a second polymer binder 151, the adhesive layer can be easily formed.

[0118] According to one embodiment of the present invention, the method for applying the adhesive layer slurry to the surface of the porous polymer substrate 110 is not limited to any particular method, and any conventional method known in the art may be used, such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

[0119] According to one embodiment of the present invention, the adhesive layer slurry may further include a dispersion medium, which may be water. As described above, the adhesive layer slurry further includes a dispersion medium, which allows the second polymer binder to be uniformly dispersed.

[0120] According to one embodiment of the present invention, the method for manufacturing an electrochemical device may include the step of drying the slurry for the coating layer to form a coating layer. As described above, by including the step of drying the slurry for the coating layer to form a coating layer, damage to the coating layer can be minimized and the solvent or dispersion medium contained in the slurry can be easily removed.

[0121] According to one embodiment of the present invention, the method for manufacturing an electrochemical device may include the step of drying the slurry for the adhesive layer to provide an adhesive layer. As described above, by including the step of drying the slurry for the adhesive layer to provide an adhesive layer, damage to the adhesive layer can be minimized and the dispersion medium contained in the slurry can be easily removed.

[0122] According to one embodiment of the present invention, the method for manufacturing an electrochemical device may include the steps of applying and drying a slurry for a coating layer, and then drying the slurry for an adhesive layer to provide a coating layer and an adhesive layer, respectively. As described above, by including the steps of applying and drying a slurry for a coating layer, and then drying the slurry for an adhesive layer to provide a coating layer and an adhesive layer, respectively, the coating layer and the adhesive layer may be easily formed.

[0123] According to one embodiment of the present invention, the drying process is performed under appropriate time conditions to minimize the occurrence of surface defects in the coating layer. The drying process may be performed using auxiliary drying devices such as a drying oven or hot air within an appropriate range.

[0124] According to one embodiment of the present invention, the separator is interposed between the anode and cathode and fabricated into an electrode assembly by a lamination process in which the separator is bonded by applying heat and / or pressure. In one embodiment of the present invention, the lamination process can be performed using a roll press device including a pair of pressure rollers. That is, the anode, separator, and cathode can be sequentially stacked and then inserted between the pressure rollers to achieve interlayer bonding. In this case, the lamination process can be performed using a hot press method.

[0125] One embodiment of the present invention provides an electrochemical device comprising a positive electrode 300, a negative electrode 500, and a separator 100, wherein the separator 100 is a separator for the electrochemical device interposed between the positive electrode 300 and the negative electrode 500.

[0126] An electrochemical device according to an embodiment of the present invention can improve the performance of a battery and extend the life of the battery.

[0127] 3 is a schematic diagram of an electrochemical device according to one embodiment of the present invention, and the electrochemical device according to one embodiment of the present invention will be specifically described with reference to FIG.

[0128] In this specification, the electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and includes primary and secondary batteries. In this specification, the secondary battery is a battery that can be charged and discharged, and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-metal hydride 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 containing a liquid electrolyte, an all-solid-state battery containing a solid electrolyte, a lithium polymer battery containing a gel polymer electrolyte, and a lithium metal battery using lithium metal as a negative electrode.

[0129] According to one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector, the positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin. The positive electrode active material may be a layered compound such as lithium manganese composite oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x Lithium manganese oxides such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by the chemical formula LiMnO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x=0.01 to 0.3) 1- xM xO2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1), or a lithium manganese composite oxide represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a part of Li in the chemical formula is substituted with an alkaline earth metal ion; a disulfide compound; and it can contain a mixture of one or more of Fe2(MoO4)3.

[0130] According to one embodiment of the present invention, the negative electrode includes a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. As the negative electrode active material, the negative electrode includes carbon such as lithium metal oxide, graphitizable carbon, and graphite-based carbon; LixFe2O3 (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, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8), etc.; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; and it can contain a mixture of one or more selected from titanium oxides.

[0131] According to one embodiment of the present invention, the conductive material may be, for example, any one selected from the group consisting of graphite, carbon black, carbon or metal fiber, metal powder, conductive whisker, conductive metal oxide, activated carbon, and polyphenylene derivatives, or a mixture of two or more of these conductive materials. More specifically, the conductive material may be any one selected from the group consisting of natural graphite, artificial graphite, Super-P, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more of these conductive materials.

[0132] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. For example, stainless steel, copper, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like can be used.

[0133] 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-co-trichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples of suitable cellulose acetate include, but are not limited to, cyanoethyl acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxyl methyl cellulose.

[0134] In the present invention, the positive electrode slurry for preparing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound, specifically, N-methylpyrrolidone (ADC-01, LG Chemicals).

[0135] According to one embodiment of the present invention, the content of the dispersant in the positive electrode slurry may be more than 0 parts by weight and not more than 0.5 parts by weight, relative to 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant in the positive electrode slurry may be more than 0.05 parts by weight and not more than 0.4 parts by weight, relative to 100 parts by weight of the positive electrode slurry.

[0136] According to one embodiment of the present invention, the negative electrode slurry for preparing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (manufactured by Junsei Corporation).

[0137] According to one embodiment of the present invention, the content of the dispersant in the negative electrode slurry may be more than 0 parts by weight and not more than 0.5 parts by weight per 100 parts by weight of the negative electrode slurry. Specifically, the content of the dispersant in the negative electrode slurry may be more than 0.05 parts by weight and not more than 0.4 parts by weight per 100 parts by weight of the negative electrode slurry.

[0138] According to one embodiment of the present invention, the electrochemical device prepared as described above can be placed in a suitable case and filled with an electrolyte to fabricate a battery.

[0139] According to one embodiment of the present invention, the electrolyte is + B - A salt having the structure: + Li + , Na + , K. + or a combination thereof, - is PF6 -, BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - or a salt containing an anion such as the above, or an ion consisting of a combination thereof, may be dissolved or dissociated in an organic solvent consisting of, but not limited to, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone (γ-butyrolactone), or a mixture thereof.

[0140] One embodiment of the present invention provides a battery module including a battery containing the electrochemical device 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, power tools powered by a battery motor; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0141] According to one embodiment of the present invention, the first portion of the separator may be disposed to face the positive electrode, and the second portion of the separator may be disposed to face the negative electrode. Specifically, the first portion of the separator may be formed to contact the positive electrode, and the second portion of the separator may be formed to contact the negative electrode. As described above, by disposing the first portion of the separator to face the positive electrode and the second portion of the separator to face the negative electrode, it is possible to improve the efficiency of capturing transition metal ions generated at the positive electrode and prevent pore clogging. [Example]

[0142] Hereinafter, the present invention will be described in detail with reference to examples. However, the examples of the present invention can be modified in various different forms, and the scope of the present invention should not be construed as being limited to the examples described below. The examples in this specification are provided to more completely explain the present invention to those skilled in the art.

[0143] Example 1 (1) Separation membrane manufacturing The first mixture was a mixture of polyethylene (weight average molecular weight 900,000) and inorganic Al2O3 powder with a D50 particle size of 600 nm in a weight ratio of 80:20, and the second mixture was a mixture of polyethylene (weight average molecular weight 900,000) and inorganic Al2O3 powder with a D50 particle size of 600 nm in a weight ratio of 95:5. The second mixture was co-extruded and the drawing temperature was adjusted to 105°C and the heat setting temperature to 130°C, respectively. A porous polymer substrate made of polyolefin resin (total thickness: 8 μm, thickness of first portion: 4 μm, thickness of second portion: 4 μm, porosity of first portion: 60 vol%, porosity of second portion: 45 vol%) was produced by a wet method.

[0144] (2) Manufacturing of the positive electrode Cathode active material (LiNi 0.8 Mn 0.1 Co 0.1O2), conductive material (carbon black), dispersant (N-methylpyrrolidone, ADC-01, LG Chemicals), and binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for the positive electrode active material layer, with the remaining components (excluding water) being 50 wt%. The slurry was then applied to the surface of an aluminum thin film (10 μm thick) and dried to prepare a positive electrode having a positive electrode active material layer (120 μm thick).

[0145] (3) Manufacturing of the negative electrode Graphite (a blend of natural and artificial graphite), conductive material (carbon black), dispersant (Polyvinylpyrrolidone, Junsei), and binder resin (a blend of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for the negative electrode active material layer, with the remaining components (excluding water) at a concentration of 50 wt%. The slurry was then applied to the surface of a copper thin film (10 μm thick) and dried to prepare a negative electrode having a negative electrode active material layer (120 μm thick).

[0146] (4) Lamination process The separator of the present invention was interposed between the negative electrode and the positive electrode, and the resulting stack was subjected to a lamination process to obtain an electrochemical device. The first portion of the separator was positioned so as to contact the positive electrode. The lamination process was performed using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0147] <Example 2> An electrochemical element was produced in the same manner as in Example 1, except that the porosity of the first portion was 45% by volume and the porosity of the second portion was 60% by volume.

[0148] Example 3 An electrochemical element was produced in the same manner as in Example 1, except that the porosity of the first portion was 50% by volume and the porosity of the second portion was 50% by volume.

[0149] <Comparative Example 1> A separator was prepared as follows, and an electrochemical device was prepared in the same manner as in Example 1, except that the separator of Comparative Example 1 was interposed between the prepared negative electrode and positive electrode.

[0150] (1) Separation membrane manufacturing A mixture of polyethylene (weight average molecular weight 900,000) and Al2O3 powder with a D50 particle size of 600 nm as inorganic particles was mixed in a weight ratio of 80:20, and the mixture was extruded. The drawing temperature was adjusted to 105°C and the heat setting temperature to 130°C, and a porous polymer substrate (total thickness: 8 μm) made of polyolefin resin material was manufactured using a wet method.

[0151] <Comparative Example 2> A separator was prepared in the same manner as in Example 1, and an electrochemical device was prepared in the same manner as in Example 1, except that the positive electrode and the second portion of the separator were interposed so as to be in contact with the positive electrode.

[0152] <Experimental Example 1: Measurement of air permeability of separation membrane> The air permeability (air permeability time, Gurley) of the separation membranes manufactured in Example 1, Comparative Example 1, and Comparative Example 2 was measured according to the ASTM D-2873 method. The Gurley value was measured using a Gurley-type Densometer (No. 158) manufactured by Toyoseiki Co., Ltd., in accordance with the JIS Gurley measurement method. The air permeability value was measured by passing 100 ml of air through 1 in of the separation membrane under a pressure of 12.2 inH2O. 2 The time (seconds) required for the air to pass through the cross section of the sample was expressed as the aeration time.

[0153] <Experimental Example 2: Measurement of Breakdown Voltage> The breakdown voltage was measured using an AC / DC / IR Hi-Pot tester.

[0154] A 5x5cm cut separation membrane sample was placed between aluminum jigs (upper jig diameter 30mm, lower jig 50x100mm), and the voltage at which the fail condition (>0.5mA, 3 seconds) occurred was measured using a Hi-pot tester. The measurement conditions were DC, current 0.5mA, and voltage step-up 100V / s (up to 3kV). The measured value was expressed as the average of 30 samples.

[0155] <Experimental Example 3: Short circuit during assembly> When a voltage of 50 V was applied for 0.1 seconds to the electrochemical elements of Example 1, Comparative Example 1, and Comparative Example 2, if the flowing current was 0.5 mA or more, it was determined that a short circuit had occurred. Ten electrochemical elements of each of Example 1, Comparative Example 1, and Comparative Example 2 were manufactured, and it was determined whether or not a short circuit had occurred.

[0156] <Experimental Example 4: Measurement of cycle capacity retention rate> The electrochemical devices of Example 1, Comparative Example 1, and Comparative Example 2 were charged and discharged once at 0.1 C in a voltage range of 3.0 V to 4.4 V in a chamber at 25° C., and then charged and discharged at 1.0 C for 300 cycles to measure their life characteristics. The life characteristics were expressed as a capacity retention rate calculated by the ratio of the discharge capacity after 300 cycles to the discharge capacity after the first cycle. <Experimental Example 5: Resistance Increase Rate> The increase rate of DCIR resistance was measured before and after 300 cycles for the electrochemical devices of Example 1, Comparative Example 1, and Comparative Example 2. The DCIR resistance was measured at a SOC (State of Charge) of 50% and discharged at 2.5 C for 10 seconds.

[0157] [Table 1] Referring to Table 1, it was confirmed that Comparative Example 1 was not suitable for use as a separator due to poor insulation properties caused by excessively high porosity of the separator. Furthermore, it was confirmed that Comparative Example 2 deteriorated the performance of the electrochemical device due to metal ions generated on the surface opposite the positive electrode being accumulated in the porous polymer substrate with low porosity.

[0158] In contrast, in Examples 1 to 3, by using a separation membrane including a first portion and a second portion in which pores of appropriate sizes were formed, it was confirmed that appropriate ventilation was achieved and the performance of the electrochemical element was not reduced compared to the comparative example.

[0159] As described above, the separator for an electrochemical device according to one embodiment of the present invention can prevent pore clogging by adjusting the pore size, porosity, and inorganic particle content of the portion adjacent to and separated from the positive electrode, thereby improving the efficiency of capturing transition metal ions generated at the positive electrode, thereby preventing battery degradation and improving battery life. [Explanation of symbols]

[0160] 100: Separation membrane for electrochemical elements 110: Porous polymer base material 111: Part 1 113:Second part 130: Coating layer 131: First polymer binder 133: Inorganic particles 150: Adhesive layer 151: Second polymer binder 300: Positive electrode 500: Negative electrode

Claims

1. a porous polymer substrate containing inorganic particles; a first portion adjacent to one surface of the porous polymer substrate and a second portion opposite the first portion; the weight of the inorganic particles contained in the first portion is greater than the weight of the inorganic particles contained in the second portion; The separator for an electrochemical element, wherein the inorganic particles are capable of adsorbing transition metal ions.

2. 2. The separator for an electrochemical device according to claim 1, wherein the inorganic particles are one selected from the group consisting of zeolite, silica gel, carbon fiber, porous carbon, porous metal oxide, metal-organic composite (MOF), and combinations thereof.

3. The separator for an electrochemical device according to claim 1 , wherein the inorganic particles contained in the first portion and the inorganic particles contained in the second portion are the same or different.

4. The separator for an electrochemical device according to claim 1 , wherein the porous polymer substrate is a polyolefin resin.

5. The separator for an electrochemical device according to claim 1 , wherein the size of the pores in the first portion is larger than the size of the pores in the second portion.

6. the size of the pores included in the first portion is 20 μm or more and 100 μm or less; The separator for an electrochemical device according to claim 1 , wherein the size of the pores contained in the second portion is 20 μm or more and 100 μm or less.

7. The separator for an electrochemical device according to claim 1 , wherein the porosity of the first portion is greater than the porosity of the second portion.

8. the porosity of the first portion is 50% by volume or more and 70% by volume or less; 2. The separator for an electrochemical device according to claim 1, wherein the porosity of the second portion is 40% by volume or more and 50% by volume or less.

9. 2. The separator for an electrochemical device according to claim 1, wherein the thickness of the first portion is equal to or smaller than the thickness of the second portion.

10. The separator for an electrochemical device according to claim 1 , wherein the first portion is provided adjacent to the positive electrode.

11. The separator for an electrochemical device according to claim 1 , wherein a portion of the surface of the inorganic particle is provided to protrude outward from the porous polymer substrate.

12. 2. The separator for an electrochemical device according to claim 1, wherein the separator for an electrochemical device has a thickness of 9 [mu]m or less.

13. a positive electrode; a negative electrode; and a separator; An electrochemical element, wherein the separator is the separator for an electrochemical element according to any one of claims 1 to 12, interposed between the positive electrode and the negative electrode.

14. the first portion of the separation membrane is disposed to face the positive electrode, The electrochemical device according to claim 13 , wherein the second portion of the separator is disposed so as to face the negative electrode.

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