Electrode assembly including adhesive insulating coating portion, and electrochemical element including the same

Abstract

The present invention relates to an electrode assembly in which adhesion is imparted to the insulating coating portion to improve the adhesion between the positive electrode and the separator membrane, and to an insulating coating composition for the same. An electrode assembly according to one aspect of the present invention has the advantage of excellent wet adhesion between the electrode and the separator membrane, which improves the phenomenon of the separator membrane bending, thereby improving the safety of the electrochemical element.

Description

[Technical Field]

[0001] The present invention relates to an electrode assembly including an insulating coating portion, and an electrochemical element including the same.

[0002] This application claims priority based on Korean Patent Application No. 2023-0068575, filed on 26 May 2023, and all contents disclosed in the specification and drawings of said application are incorporated into this application. [Background technology]

[0003] The increasing technological development and demand for mobile devices are leading to a rapid increase in the demand for rechargeable batteries as an energy source. Recently, rechargeable batteries have been used as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs). As a result, research into rechargeable batteries that can meet diverse needs is actively underway.

[0004] In particular, there is a high demand for lithium-ion secondary batteries with high energy density, high discharge voltage, and output stability. Among these, lithium-ion secondary batteries used as power sources for electric vehicles and hybrid electric vehicles require high-output characteristics that allow them to deliver large output in a short time. To accommodate such lithium-ion secondary batteries, there continues to be interest in improving battery safety.

[0005] On the other hand, secondary batteries are classified into jelly roll (winding type) electrode assemblies, stack type (layered type) electrode assemblies, and stack / folding type electrode assemblies, depending on the structure of the electrode assembly. Basically, the electrode assembly includes three basic components: a positive electrode, a separator membrane, and a negative electrode.

[0006] A conventional electrode assembly has a structure in which a separator is interposed between a positive electrode and a negative electrode with electrode tabs protruding on one side. However, in such a structure, when the separator shrinks due to being exposed to a heat source from the outside or an increase in temperature due to an internal short circuit, etc., there is a problem that a part of the positive electrode and the negative electrode comes into contact and a short circuit occurs.

[0007] Therefore, research is being conducted to solve the above problems using insulating materials, such as inserting an insulating layer into a part of the electrode assembly. As an example, research is being conducted to prevent the above short circuit problems, lithium precipitation, ignition, etc. by providing an insulating layer using a PVDF-based resin on the positive electrode.

[0008] However, problems have been reported for PVDF-based insulating materials under development, such as peeling due to insufficient adhesiveness or dissolution by the electrolyte when the electrolyte is injected into the electrode assembly. A short circuit phenomenon still reported is that the adhesive force between the components of the electrode assembly decreases, the separator bends without adhering to the electrode, and a part of the positive electrode and the negative electrode comes into contact. Summary of the Invention Problems to be Solved by the Invention

[0009] Therefore, the present invention aims to solve the above problems and provide an electrode assembly that effectively solves the short circuit problem between the positive electrode and the negative electrode, and an electrochemical element including the same.

[0010] In particular, the electrode assembly of the present invention includes an insulating coating portion and aims to provide an electrode assembly having excellent adhesion between the electrode and the separator.

[0011] As an example, the electrode assembly of the present invention includes an insulating coating portion and aims to provide an electrode assembly having excellent adhesion between the positive electrode and the separator. Means for Solving the Problems

[0012] To solve the above problems, According to one aspect of the present invention, an electrode assembly of the following embodiment is provided.

[0013] The electrode assembly according to the first embodiment is including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, at least one of the positive electrode and the negative electrode includes a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire outer peripheral portion of one surface of the active material layer. The wet adhesion between the positive electrode or the negative electrode provided with the insulating coating portion and the separator can be 1 gf / 20 mm to 20 gf / 20 mm.

[0014] According to the second embodiment, in the first embodiment, at least one of the positive electrode and the negative electrode can include an active material layer and an insulating coating portion formed around the entire outer peripheral portion of one surface of each of the active material layers on both surfaces of the current collector.

[0015] According to the third embodiment, in the first embodiment or the second embodiment, the insulating coating portion includes inorganic particles and a binder, the binder can include two kinds of adhesive binders with a difference in glass transition temperature (Tg) of 100°C or less.

[0016] According to the fourth embodiment, in any one of the first embodiment to the third embodiment, the insulating coating portion includes inorganic particles and a binder, the binder can include a first adhesive binder with a glass transition temperature (Tg) of 50°C or higher and a second adhesive binder with a glass transition temperature (Tg) of 20°C or lower.

[0017] According to another aspect of the present invention, an insulating coating composition of the following embodiment is provided.

[0018] The insulating coating composition according to the fifth embodiment is: It contains inorganic particles and a binder, The binder may include two adhesive binders having a difference in glass transition temperature (Tg) of 100°C or less.

[0019] The insulating coating composition according to the sixth embodiment is: It contains inorganic particles and a binder, The binder may include a first adhesive binder having a glass transition temperature (Tg) of 50°C or higher, and a second adhesive binder having a glass transition temperature (Tg) of 20°C or lower.

[0020] According to the seventh embodiment, in the sixth embodiment, The first adhesive binder may include an aqueous particulate binder.

[0021] According to the eighth embodiment, in the sixth or seventh embodiment, The first adhesive binder may include an aqueous particle-type binder with a particle size of 250 nm or more.

[0022] According to the ninth embodiment, in any one embodiment from the sixth to the eighth embodiment, The second adhesive binder may include an aqueous particulate binder, a solution-type binder, or a mixture thereof.

[0023] According to the tenth embodiment, in any one embodiment of the sixth to ninth embodiments, The second adhesive binder may include an aqueous particle-type binder with a particle size of 250 nm or less.

[0024] According to the 11th embodiment, in any one embodiment of the 6th to 10th embodiments, The weight ratio of the first adhesive binder and the second adhesive binder may be 1:9 to 9:1.

[0025] According to the 12th embodiment, in any one embodiment from the 5th to the 11th embodiment, The weight ratio of the inorganic particles to the binder may be 7:3 to 9:1.

[0026] According to another aspect of the present invention, an electrochemical element of the following embodiment is provided.

[0027] The electrochemical element according to the 13th embodiment is An electrode assembly according to any one embodiment of the first to fourth embodiments can be housed in a case.

[0028] According to another aspect of the present invention, a method for manufacturing an electrode assembly of the following embodiment is provided.

[0029] The method for manufacturing an electrode assembly according to the 14th embodiment is as follows: The steps include preparing a current collector and an electrode having an active material layer on at least one surface of the current collector, The steps include forming an insulating coating portion containing inorganic particles and a binder around the entire outer periphery of one surface of the active material layer, The step includes bringing a separation film into contact with the surface on which the insulating coating portion is formed, and then rolling it, The electrode is at least one of a positive electrode and a negative electrode. The wet adhesion between the electrode on which the insulating coating portion is formed and the separation film may be 1 gf / 20 mm to 20 gf / 20 mm. [Effects of the Invention]

[0030] An electrode assembly according to one embodiment of the present invention is provided with an adhesive insulating coating portion around the outer circumference of the electrode, thereby increasing the adhesive strength between the electrode and the separator film and suppressing the occurrence of short circuits between the electrodes.

[0031] This reduces the risk of explosion and fire caused by the short circuit, thereby contributing to improved safety. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows one embodiment in which an electrode active material layer 11 is formed on a current collector on which a tab portion 1 is formed, and an insulating coating portion 20 is formed around the entire outer circumference of one surface of the electrode active material layer 11, according to one embodiment of the present invention. [Figure 2] This figure shows a side view of one embodiment of an assembly in which an electrode active material layer 11, an insulating coating portion 20, and a separation film 30 are sequentially laminated on a current collector 10 on which a tab portion 1 is formed, according to one embodiment of the present invention. [Figure 3] This figure shows a vertical cross-sectional view of the central part of one embodiment of an assembly in which an electrode active material layer 11, an insulating coating portion 20, and a separation film 30 are sequentially laminated on a current collector 10 on which a tab portion 1 is formed, according to one embodiment of the present invention. [Modes for carrying out the invention]

[0033] The present invention will be described in detail below.

[0034] In this specification, when a part "includes" a component, this means, unless otherwise stated, that it may include other components rather than excluding them.

[0035] In this specification, the terms "A and / or B" mean "A or B, or both."

[0036] The present invention relates to an electrode assembly and an electrochemical element containing the same. Examples of the electrochemical element include primary batteries, secondary batteries, supercapacitors, and electric double-layer capacitors. More specifically, the secondary battery may be a lithium-ion secondary battery.

[0037] The electrode assembly and electrochemical element of the present invention will be described in more detail below with reference to the drawings.

[0038] An electrode assembly according to one aspect of the present invention has a structure comprising a positive electrode, a negative electrode, and a separation membrane interposed between the positive electrode and the negative electrode. In this case, at least one of the positive electrode and the negative electrode includes a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire outer circumference of one surface of the active material layer, wherein the wet adhesion between the positive electrode or negative electrode provided with the insulating coating portion and the separation membrane can be 1 gf / 20 mm to 20 gf / 20 mm.

[0039] In one embodiment of the present invention, the positive electrode includes an active material layer formed on at least one surface of the positive electrode and an insulating coating portion formed around the entire outer periphery of one surface of the active material layer, wherein the wet adhesion between the surface of the positive electrode on which the insulating coating portion is provided and the separation film can be 1 gf / 20 mm to 20 gf / 20 mm.

[0040] In another embodiment of the present invention, the present invention includes an active material layer formed on at least one surface of the negative electrode and an insulating coating portion formed around the entire outer periphery of one surface of the active material layer, wherein the wet adhesion between the surface of the negative electrode on which the insulating coating portion is provided and the separation film can be 1 gf / 20 mm to 20 gf / 20 mm.

[0041] In yet another embodiment of the present invention, the positive electrode and the negative electrode each include an active material layer formed on at least one surface and an insulating coating portion formed around the entire outer periphery of one surface of the active material layer, wherein the wet adhesion between the surface of the positive electrode on which the insulating coating portion is provided and the separation film, and / or the wet adhesion between the surface of the negative electrode on which the insulating coating portion is provided and the separation film, can be 1 gf / 20 mm to 20 gf / 20 mm.

[0042] Figure 1 shows a schematic diagram of an example of the electrode. Specifically, Figure 1 shows one embodiment in which an electrode active material layer 11 is formed on a current collector on which a tab portion 1 is formed, and an insulating coating portion 20 is formed around the entire outer circumference of one surface of the electrode active material layer.

[0043] Referring to Figure 1, in one embodiment of the present invention, the electrode may have a structure comprising a current collector, an electrode active material layer 11 formed on at least one surface of the current collector, and an electrode tab 1 extending from the current collector. In this case, the insulating coating portion 20 is formed to surround the entire outer periphery of one surface of the electrode active material layer 11.

[0044] Figure 2 shows a schematic diagram of one embodiment in which the electrode and the separation membrane are attached. Specifically, Figure 2 shows that, according to one embodiment of the present invention, the electrode active material layer 11 formed on the current collector 10 on which the tab portion 1 is formed includes an insulating coating portion 20 around its outer circumference, so that the insulating coating portion 20 can be positioned between the electrode active material layer 11 and the separation membrane 30. This improves the adhesion between the electrode active material layer and the separation membrane and has the effect of improving the bending phenomenon of the separation membrane during the manufacture of the electrode assembly.

[0045] In one embodiment of the present invention, the electrode may comprise electrode active material layers on both sides of the current collector, and may include an insulating coating portion formed around the entire outer circumference of one surface of each electrode active material layer. In this case, the electrode is a positive electrode and / or a negative electrode, but the present invention is not limited thereto.

[0046] Figure 3 shows a schematic diagram of one embodiment in which the electrode and separation membrane are attached. Specifically, Figure 3 shows a vertical cross-sectional view centered on the central part of the assembly to which the electrode and separation membrane are attached. Referring to Figure 3, since the insulating coating portion 20 is formed around the outer periphery of the electrode active material layer 11, the insulating coating portion is not included on the inner area of ​​the electrode active material layer 11. In this case, in order to prevent the electrode active material layer and the separation membrane from adhering due to the thickness of the insulating coating portion itself, it is desirable to form the insulating coating portion thinly during the manufacture of the electrode assembly so that when pressure is applied between the electrode and the separation membrane, one surface of the electrode active material layer can make sufficient contact with the separation membrane.

[0047] In one embodiment of the present invention, the insulating coating portion is formed to surround the entire outer periphery of one surface of the electrode active material layer, and can be formed to have a thickness of, for example, 0.5 μm to 1 μm. Conventionally, due to phenomena such as the sliding of the electrode slurry during the manufacture of the electrode assembly, a thickness deviation of, for example, about 3 μm or more may occur in the electrode active material layer. However, the present invention has the advantage that by forming a thin insulating coating portion around the outer periphery of the electrode active material layer as described above, it is possible to improve the overall thickness deviation of the electrode, improve the adhesion between the electrode and the separation membrane, and improve the bending phenomenon of the separation membrane, thereby improving the safety of the battery. However, the mechanism of the present invention is not limited to this.

[0048] In one embodiment of the present invention, the insulating coating portion formed around the entire outer periphery of one surface of the electrode active material layer may have an area of, for example, 5% to 50% of the total area of ​​one surface of the electrode active material layer, 10% to 30% of the total area of ​​the one surface of the electrode active material layer, or 15% to 20% of the total area of ​​the one surface of the electrode active material layer. When the insulating coating portion has an area within the above ranges based on the area of ​​one surface of the electrode active material layer, it is desirable to maintain the effect of the insulating coating portion and in terms of the energy density of the electrode, but the present invention is not limited thereto.

[0049] In one embodiment of the present invention, the area of ​​the insulating coating portion can be measured by obtaining an image of the top surface of the electrode on which the insulating coating portion is formed, and then measuring the area occupied by the insulating coating portion relative to the total area of ​​the active material layer, when the direction in which the current collector, electrode active material layer, and insulating coating portion are stacked is the vertical direction. In this case, the image of the top surface of the electrode is not particularly limited to a photographic image, a microscope image such as an SEM image, etc.

[0050] The electrode assembly improves upon the current situation where the separation film does not adhere to the electrode and bends within the electrode assembly, by having a wet adhesion force of 1 gf / 20 mm to 20 gf / 20 mm at the interface between the electrode and the separation film where the insulating coating portion is provided. This effectively prevents short circuits between electrodes.

[0051] In this specification, the wet adhesive strength refers to the adhesive strength measured in the presence of an electrolyte, similar to the environment in which the electrode assembly is driven as a battery. Even if the dry adhesive strength between the electrode, such as the positive or negative electrode, and the separation membrane is high, when the electrode assembly comes into contact with the electrolyte and each component of the electrode assembly is wet by the electrolyte, a problem may arise in which the wet adhesive strength is not sufficiently secured due to a decrease in frictional force between the components or dissolution of the adhesive components. To solve this problem, according to one aspect of the present invention, an electrode assembly is provided in which the wet adhesive strength between one surface of the electrode on which the insulating coating portion is provided and the separation membrane is secured in the range of 1 gf / 20 mm to 20 gf / 20 mm.

[0052] In one embodiment of the present invention, the wet adhesion between the electrode and the separation membrane is, for example, 5 gf / 20 mm to 15 gf / 20 mm, or 8 gf / 20 mm to 12 gf / 20 mm. For example, the wet adhesion between the electrode and the separation membrane is 10 gf / 20 mm, but the present invention is not limited thereto. When the wet adhesion between the electrode and the separation membrane is within the above range, it is advantageous in that the adhesion of the separation membrane can be maintained even after the electrolyte is injected into the electrode assembly.

[0053] In this specification, the wet adhesion strength can be measured by, for example, the following method, but is not limited thereto. First, samples of the electrode and separation membrane, each having the insulating coating formed around the entire outer circumference of one surface of the active material layer, are cut to a size of 25 mm × 60 mm. Then, an electrode-separation membrane sample is manufactured by applying pressure at 6.5 MPa for 1 second at 60°C using a heat press. After that, the electrode-separation membrane sample is placed in a pouch, 1 g of electrolyte is poured in and impregnated for 1 day, and then the electrode-separation membrane sample is removed from the pouch and attached to a UTM device (Universal Tester, LLOYD Instrument LF Plus), and the 90° peel strength is measured at a speed of 300 mm / min.

[0054] In one embodiment of the present invention, the electrode assembly exhibits excellent not only wet adhesion between the electrode and the separation membrane, but also dry adhesion.

[0055] In one embodiment of the present invention, the dry adhesive strength between the electrode and the separation membrane is, for example, 5gf / 25mm to 30gf / 25mm, 10gf / 25mm to 28gf / 25mm, 15gf / 25mm to 25gf / 25mm, or 18gf / 25mm to 23gf / 25mm. For example, the dry adhesive strength between the electrode and the separation membrane is 20gf / 25mm.

[0056] In this specification, the dry adhesive strength can be measured by, for example, the following method, but is not limited thereto. After obtaining samples of the electrode and separation membrane, each having the insulating coating portion formed around the entire outer circumference of the active material layer, cut to a size of 25 mm × 60 mm, an electrode-separation membrane sample is manufactured by applying pressure at 6.5 MPa for 1 second at 60°C using a heat press. Then, the electrode-separation membrane sample is mounted on a UTM device (LLOYD Instrument LF Plus), and the 180° peel strength is measured at a speed of 300 mm / min.

[0057] In one embodiment of the present invention, the electrode assembly also exhibits excellent peel strength between the active material layer and the insulating coating portion.

[0058] In this specification, the peel strength refers to the adhesive strength between the insulating coating portion formed around the entire outer periphery of the active material layer and the active material layer.

[0059] In one embodiment of the present invention, the peel strength between the active material layer and the insulating coating portion is, for example, 5gf / 15mm to 30gf / 15mm, 10gf / 15mm to 30gf / 15mm, 15gf / 15mm to 25gf / 15mm, or 20gf / 15mm to 25gf / 15mm. For example, the peel strength between the active material layer and the insulating coating portion is 20gf / 15mm.

[0060] In this specification, the peel strength can be measured by, for example, the following method, but is not limited thereto. The positive electrode to be measured is cut to a size of 15 mm x 100 mm. Double-sided adhesive tape is attached to a glass plate, and the prepared electrode is attached so that the insulating coating portion and the surface of the active material layer are adhered to the adhesive tape. Then, the end of the adhered insulating coating portion is attached to a UTM device (LLOYD Instrument LF Plus), and force is applied at a measurement speed of 300 mm / min at 180° to measure the force required to peel the insulating coating portion from the active material layer.

[0061] According to one embodiment of the present invention, the insulating coating portion includes inorganic particles and a binder. In this case, the binder includes an adhesive binder in order to exhibit the adhesive strength described above.

[0062] In one embodiment of the present invention, the binder included in the insulating coating portion is an adhesive binder and may include two types of binders having different glass transition temperatures (Tg).

[0063] The following describes in detail other embodiments of the present invention of insulating coating compositions.

[0064] According to another aspect of the present invention, a composition for insulating coatings is provided.

[0065] The insulating coating composition described above can be used to form an insulating coating portion on an electrode within the electrode assembly described above.

[0066] The insulating coating composition comprises inorganic particles and a binder, the binder comprising a first adhesive binder having a glass transition temperature (Tg) of 50°C or higher and a second adhesive binder having a glass transition temperature (Tg) of 20°C or lower.

[0067] According to one aspect of the present invention, the insulating coating composition, by including an adhesive binder, exhibits the effect of improving the adhesion between the positive electrode and the separation film. In this case, by including two types of adhesive binders with different glass transition temperature ranges, the binder can exhibit not only excellent wet and dry adhesion but also excellent adhesion (peel strength) between the active material layer and the insulating coating portion.

[0068] Specifically, the two adhesive binders contained in the insulating coating composition may be referred to as the first adhesive binder and the second adhesive binder, respectively. The first adhesive binder and the second adhesive binder can have the function of stably maintaining the insulating performance of the insulating coating portion by binding inorganic particles to each other within the insulating coating portion.

[0069] In one embodiment of the present invention, the first adhesive binder may further have the function of improving the adhesion between the insulating coating portion and the separation film, specifically, the adhesion between the positive electrode and the separation film, although its function is not limited thereto. Furthermore, the second adhesive binder may further have the function of improving the adhesion between the insulating coating portion and the active material and / or current collector, although its function is not limited thereto. As described above, in order to improve the adhesion between the positive electrode and the separation film, and the adhesion between the active material layer and the insulating coating portion, the binder may include two types of binders having different glass transition temperatures, but the effects of the present invention are not limited thereto.

[0070] In this specification, the glass transition temperature (Tg) refers to the temperature range in which the glass transition of the binder occurs. The glass transition temperature can be measured by known methods for measuring glass transition temperature, such as differential scanning calorimeter (DSC), specific heat measurements, dilatometer, thermomechanical analysis (DMA), thermal expansion measurement (TAM), micro-heat-transfer measurement, isothermal compressibility, and heat capacity measurement.

[0071] In this specification, the glass transition temperature value refers to a value measured by a method that measures the heat flow in a binder sample during a linear temperature rise process, particularly using a differential scanning calorimeter (DSC), and it will be obvious to an ordinary person that the numerical value of the glass transition temperature includes a predetermined range of measurement error, for example, a range of -5% to +5%, based on the stated value.

[0072] In one embodiment of the present invention, the binder may include two adhesive binders having a difference in glass transition temperature (Tg) of 100°C or less. More specifically, the binder may include two adhesive binders having a difference in glass transition temperature of 90°C or less. More specifically, the binder may include two adhesive binders having a difference in glass transition temperature of, for example, 50°C to 90°C, 60°C to 80°C, 65°C to 75°C, or 65°C to 70°C.

[0073] In one embodiment of the present invention, the glass transition temperature of the first adhesive binder may be, for example, 50°C to 80°C, or 50°C to 70°C.

[0074] In one embodiment of the present invention, the glass transition temperature of the second adhesive binder may be, for example, -50°C to 20°C, -40°C to 0°C, or -30°C to -10°C.

[0075] In one embodiment of the present invention, the first adhesive binder has a glass transition temperature of 50°C or higher and may be an aqueous particulate binder.

[0076] In this specification, the term "aqueous particulate binder" refers collectively to a binder that exhibits a particulate shape when dispersed in an aqueous solvent such as water (H2O). The type of particulate binder is not particularly limited as long as it satisfies the above characteristics, and may be, for example, an acrylic polymer, a rubber polymer, a cellulosic polymer, or a mixture thereof. The acrylic polymer may include, for example, polyalkyl (meth)acrylate, and the "alkyl" may be a C1-C5 alkyl, but is not particularly limited thereto. The rubber polymer is a rubber polymer containing at least one butadiene unit, and may include, but is not limited to, polybutadiene rubber, styrene-butadiene rubber, nitrile butadiene rubber, etc. The cellulosic polymer refers collectively to cellulose and cellulose derivatives, and may include, but is not limited to, cellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose phthalate, etc.

[0077] In one embodiment of the present invention, the first adhesive binder includes an aqueous particle-type binder, and more specifically, may consist solely of an aqueous particle-type binder. In this case, the aqueous particle-type binder of the first adhesive binder may include particles with a larger particle size than the inorganic particles contained in the insulating coating composition, as will be described later.

[0078] Specifically, the first adhesive binder uses a water-based particle type binder, but it is desirable that it is larger than the inorganic particles of the insulating coating composition so that it does not soak between the inorganic particles within the insulating coating portion, but remains on the surface of the insulating coating portion and exhibits excellent adhesion to the separation film.

[0079] In one embodiment of the present invention, the first adhesive binder is an aqueous particle-type binder, which may include a particle size of 250 nm or more. The first adhesive binder is an aqueous particle-type binder, for example, with a particle size of 250 nm to 1 μm, or 250 nm to 500 nm, but is not limited thereto.

[0080] In this specification, the particle size of the particle binder may be a value measured using the PSD (particle size distribution) analysis method, for example, a value measured using Malvern's Mastersizer 2000.

[0081] In one embodiment of the present invention, the second adhesive binder can improve the bonding force between inorganic particles in the insulating coating portion and impregnate (soak) between the inorganic particles to improve the adhesion between the active material layer and / or the positive electrode current collector and the insulating coating portion.

[0082] For this purpose, in one embodiment of the present invention, the second adhesive binder may include an aqueous particulate binder, a solution binder, or a mixture thereof. Alternatively, the second adhesive binder may consist solely of the aqueous particulate binder or the solution binder.

[0083] In one embodiment of the present invention, if the second adhesive binder includes an aqueous particle-type binder, it is desirable that the aqueous particle-type binder is the same size as or smaller than the inorganic particles so that it can be impregnated between the inorganic particles in the insulating coating portion.

[0084] In one embodiment of the present invention, the second adhesive binder is an aqueous particle-type binder, which may include a particle size of 250 nm or less. The second adhesive binder is an aqueous particle-type binder, for example, with a particle size of 50 nm to 250 nm or 100 nm to 200 nm, but is not limited thereto.

[0085] In one embodiment of the present invention, the second adhesive binder may include a solution-type binder.

[0086] In this specification, the term "solution-type binder" refers collectively to binders that are soluble in a polar solvent containing water (H2O), and is also called a "dissolvable binder." The type of solution-type binder is not particularly limited as long as it satisfies the above characteristics, but may include, for example, a PVDF-based polymer, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyacrylamide (PAM), or a mixture of two or more of these. The PVDF-based polymer refers collectively to polymers that contain vinylidene fluoride as a monomer, such as polyvinylidene fluoride (PVDF) and polyvinylidene-co-hexafluoropropylene.

[0087] In one embodiment of the present invention, the present invention is not particularly limited as long as it can exhibit the adhesive strength described above. For example, the weight ratio of the first adhesive binder to the second adhesive binder may be 1:9 to 9:1. Specifically, the weight ratio of the first adhesive binder to the second adhesive binder may be 5:5 to 8:2.

[0088] In one embodiment of the present invention, the inorganic particles can be used without particular limitations as long as they are suitable for use in the insulating coating portion of the electrode. The inorganic particles are, for example, alumina (Al2O3), boehmite (AlOOH), silica (SiO2), titanium dioxide (TiO2), aluminum hydroxide (Al(OH)3), magnesium oxide (MgO), magnesium hydroxide (Mg(OH)2), zinc oxide (ZnO), barium titanate (BaTiO), aluminum nitride (AIN), boron nitride (BN), silicon carbide (SiC), beryllium oxide (BeO), potassium nitrate (KNO3), monoammonium phosphate (NH4H2PO4), or a mixture of two or more of these, but are not limited thereto. Specifically, the inorganic particles may include alumina (Al2O3), boehmite (AlOOH), silica (SiO2), or a mixture of two or more of these.

[0089] In one embodiment of the present invention, the inorganic particles may, for example, have an average particle size of 250 nm or more. Specifically, the average particle size of the inorganic particles is 250 nm to 1,000 μm or 250 nm to 500 μm.

[0090] In this specification, the "average particle size" is defined as D 50 This may represent the average particle size. 50 "Average particle size" refers to the particle size at the 50% point of the cumulative particle volume distribution by particle size. 50 The average particle size can be measured using the laser diffraction method. Specifically, the particles to be measured are dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size analyzer. The particle size distribution is calculated by measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam. The commercially available laser diffraction particle size analyzer can be, for example, the Microtrac S3500, but is not limited to this.

[0091] In one embodiment of the present invention, the weight ratio of the inorganic particles and the binder is not particularly limited as long as it does not hinder the objective of the present invention, but for example, it is 9:1 to 1:9. Specifically, the weight ratio of the inorganic particles and the binder is 7:3 to 9:1, more specifically 8:2. When the weight ratio of the inorganic particles and the binder is within the above range, advantageous effects can be obtained in terms of the insulating properties of the insulating coating portion, the adhesive strength of the positive electrode, and the adhesive strength of the insulating coating portion, but the present invention is not limited thereto.

[0092] The following describes in detail other configurations of the electrode assembly according to one aspect of the present invention.

[0093] positive electrode The positive electrode, as described above, includes a current collector and an active material layer formed on at least one surface of the current collector.

[0094] In one embodiment of the present invention, the positive electrode may include a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire outer periphery of the active material layer.

[0095] The current collector is not particularly limited as long as it supports the active material layer and has high conductivity without causing chemical changes to the battery. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., and aluminum-cadmium alloys can be used.

[0096] The current collector can strengthen its bonding force with the positive electrode active material by forming fine irregularities on its surface, and can be used in various forms such as film, sheet, foil, mesh, net, porous material, foam, and nonwoven fabric.

[0097] The active material layer includes a positive electrode active material and may further include a conductive material, a binder, and additives.

[0098] In one embodiment of the present invention, the positive electrode active material can include, for example, a lithium transition metal oxide, a lithium metal iron phosphate, a lithium nickel-manganese-cobalt oxide, an oxide in which a part of the lithium nickel-manganese-cobalt oxide is substituted with another transition metal, or two or more of these, but is not limited thereto. Specifically, the positive electrode active material is, for example, a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), a compound substituted with one or more transition metals, and the chemical formula Li 1+x Mn 2-x O4 (where x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2, lithium copper oxide (Li2CuO2), vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, and the chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), Ni-site type lithium nickel oxide represented by this, and the chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxide represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn), lithium metal phosphate LiMPO4 (where M = Fe, CO, Ni, or Mn), lithium nickel-manganese-cobalt oxide Li 1+x (Ni a Co b Mn c ) 1-x O2 (x = 0 to 0.03, a = 0.3 to 0.95, b = 0.01 to 0.35, c = 0.01 to 0.5, a + b + c = 1), and an oxide in which a part of the lithium nickel-manganese-cobalt oxide is substituted with aluminum, Li a [Ni b Co c Mn d Al e [[ID=​​​O2 (M1 is one or more selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S, 0.8 ≦ a ≦ 1.2, 0.5 ≦ b ≦ 0.99, 0 < c < 0.5, 0 < d < 0.5, 0.01 ≦ e ≦ 0.1, 0 ≦ f ≦ 0.1), and an oxide in which part of lithium nickel-manganese-cobalt oxide is substituted with other transition metals Li 1+x (Ni a Co b Mn c M d ) 1-x O2 (x = 0 to 0.03, a = 0.3 to 0.95, b = 0.01 to 0.35, c = 0.01 to 0.5, d = 0.001 to 0.03, a + b + c + d = 1, M is any one selected from the group consisting of Fe, V, Cr, Ti, W, Ta, Mg, and Mo), a disulfide compound, and Fe2(MoO4)3, etc. can be mentioned, but it is not limited to only these.

[0099] In one embodiment of the present invention, the conductive material is a material that plays a role in the path for electrons to move from the current collector to the positive electrode active material by electrically connecting the electrolyte and the positive electrode active material, and can be used without limitation as long as it has conductivity as a component of the electrode physically distinguishable from the carbon contained in the sulfur-carbon composite.

[0100] In one embodiment of the present invention, the conductive material can be used alone or in combination, for example, carbon black such as Super-P, Denka black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, carbon black, carbon derivatives such as carbon nanotubes and fullerenes, conductive fibers such as carbon fibers and metal fibers, metal powders such as carbon fluoride, aluminum, and nickel powder, or conductive polymers such as polyaniline, polythiophene, polyacetylene, and polypyrrole.

[0101] In one embodiment of the present invention, the content of the conductive material is 0% to 10% by weight, for example, 1% to 10% by weight, relative to the total weight of the active material layer. If the content of the conductive material is less than the above range, electron transfer between the positive electrode active material and the current collector is not easy, which may reduce the voltage and capacity. Conversely, if it exceeds the above range, the proportion of the positive electrode active material decreases relatively, which may reduce the total energy (charge) of the battery. Therefore, it is desirable to determine an appropriate content within the above range.

[0102] In one embodiment of the present invention, the positive electrode active material layer may contain a positive electrode active material and a binder polymer, but may not contain a conductive material. The advantage of this is that the positive electrode can contain more positive electrode active material because it does not contain a conductive material.

[0103] In one embodiment of the present invention, the positive electrode binder holds the positive electrode active material on the positive electrode current collector and organically connects the positive electrode active material to further enhance the binding force between them, and all binder polymers known in the industry can be used.

[0104] In one embodiment of the present invention, the binder in the positive electrode active material layer is the same as or different from the binder in the insulating coating portion, i.e., the first adhesive binder and / or the second adhesive binder, and can be selected independently of these.

[0105] In one embodiment of the present invention, the binder in the positive electrode active material layer may include, for example, a fluororesin-based binder containing polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE), a rubber-based binder containing styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, styrene-isoprene rubber, etc., a cellulose-based binder containing carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, etc., a polyalcohol-based binder, a polyolefin-based binder containing polyethylene, polypropylene, etc., a polyimide-based binder, a polyester-based binder, a polyacrylic-based binder such as polyacrylic acid (PAA), a silane-based binder, a polyurethane-based binder, or a mixture of two or more of these. Furthermore, the binder polymer may include copolymers comprising repeating units derived from two or more of these binders.

[0106] In one embodiment of the present invention, the content of the binder polymer is 0.5 wt% to 30 wt% of the total 100 wt% of the positive electrode active material layer. When the content of the binder polymer is within this range, the physical properties of the positive electrode are improved, the phenomenon of the active material and conductive material falling off in the positive electrode can be prevented, the ratio of active material to conductive material in the positive electrode can be appropriately controlled, and battery capacity can be secured.

[0107] negative electrode The negative electrode may include a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector. Alternatively, the negative electrode may be a lithium metal plate.

[0108] In one embodiment of the present invention, the negative electrode may include a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire outer periphery of the active material layer.

[0109] The aforementioned negative electrode current collector is for holding the negative electrode active material layer, as explained in the description of the positive electrode current collector.

[0110] The negative electrode active material layer may include, in addition to the negative electrode active material, a conductive material, a binder, etc. In this case, the conductive material and binder are as described above.

[0111] The negative electrode active material is lithium (Li + This may include materials that can be reversibly intercalated or deintercalated, materials that can react with lithium ions to reversibly form lithium-containing compounds, lithium metals, or lithium alloys.

[0112] The aforementioned lithium ion (Li + Examples of materials that can reversibly insert or remove lithium ions (Li) include crystalline carbon, amorphous carbon, or mixtures thereof. + Examples of substances that can reversibly form lithium-containing compounds by reacting with ) include tin oxide, titanium nitride, or silicon. Examples of the lithium alloy include alloys of metals selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0113] separation membrane The separation membrane separates or insulates the positive and negative electrodes from each other, enables the transport of lithium ions between the positive and negative electrodes, and can be used without particular limitations as long as it is the type used in ordinary electrochemical elements. For example, the separation membrane may be provided in the form of a film.

[0114] According to one embodiment of the present invention, the separation membrane may comprise a porous substrate and a porous coating layer formed on at least one surface of the porous substrate.

[0115] The configurations of the porous substrate and the porous coating layer will be described below in an illustrative manner.

[0116] In one embodiment of the present invention, the porous substrate is an ion-conducting barrier that blocks electrical contact between the negative electrode and the positive electrode while allowing ions to pass through, and means a substrate in which a plurality of pores are formed inside. The pores have a structure in which they are interconnected, and gas or liquid can pass from one side of the substrate to the other side.

[0117] In one embodiment of the present invention, the porous substrate can be a porous polymer film containing a thermoplastic resin, from the viewpoint of providing a shutdown function. Here, the shutdown function refers to a function that, when the battery temperature rises, prevents thermal runaway of the battery by blocking ion movement through the melting of the thermoplastic resin and closing the pores of the porous substrate.

[0118] In one embodiment of the present invention, the thermoplastic resin used in the porous substrate is preferably a thermoplastic resin with a temperature of less than 200°C. Furthermore, the thermoplastic resin can be used without particular limitations as long as it is suitable for use as a substrate for a separation membrane, but is not limited to, examples of which include, but are not limited to, polyolefins, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, or mixtures of two or more of these.

[0119] In one embodiment of the present invention, the porous substrate may be a polyolefin substrate.

[0120] In one embodiment of the present invention, the porous coating layer may contain inorganic particles and further contain a binder resin, such that the inorganic particles are coated on all or at least part of their surface by the binder resin. In this case, the inorganic particles are surface-bonded and / or point-bonded via the binder resin. For example, the porous coating layer may contain inorganic particles and binder resin in a weight ratio of 95:5 to 50:50. The porous coating layer has a plurality of micropores inside, and these micropores are interconnected, giving it the structural characteristics of a porous layer that allows gas or liquid to pass from one surface to the other.

[0121] In one embodiment of the present invention, the porous coating layer may have a porous structure derived from pores created by interstitial volume between inorganic particles. The size and porosity (percentage of pore volume) of these pores can be adjusted according to the size and size distribution of the particles. Such a structure enhances the safety of the electrochemical element by increasing resistance to metallic foreign matter present on the electrodes and suppressing shrinkage of the porous polyolefin substrate.

[0122] In one embodiment of the present invention, the porous coating layer comprises a plurality of nodes, each containing inorganic particles and a binder polymer covering at least a portion of the surface of the inorganic particles, and one or more filaments formed in a thread-like manner from the binder polymer of the nodes, wherein each filament includes a node connecting portion extending from the node and connecting other nodes, and the node connecting portion may have a structure in which a plurality of filaments derived from the binder polymer intersect each other to form a three-dimensional network structure.

[0123] In one embodiment of the present invention, the porous coating layer is formed by an SRS (Safety Reinforced Separator) manufacturing method, a CCS (Ceramic Coated Separator) manufacturing method, or another known manufacturing method, but is not limited thereto.

[0124] In one embodiment of the present invention, the inorganic particles can be used without particular limitation as long as they are electrochemically stable. That is, the inorganic particles usable in the present invention are not particularly limited as long as they do not undergo oxidation and / or reduction reactions within the operating voltage range of the electrochemical element to which they are applied (e.g., 0 to 5V relative to Li / Li+). Non-limiting examples of such inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3 Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, and TiO2, and one or more of these may be included.

[0125] In one embodiment of the present invention, when the porous coating layer contains a binder resin, the binder resin may include, for example, a polyvinylidene fluoride-based resin (PVdF-based resin). In one embodiment of the present invention, the PVdF-based resin may include one or more of the following: a homopolymer of vinylidene fluoride (i.e., polyvinylidene fluoride), a copolymer of vinylidene fluoride and a monomer copolymerizable with vinylidene fluoride, and mixtures thereof. In one embodiment of the present invention, the monomer may be, for example, a fluorinated monomer and / or a chlorine-based monomer. Non-limiting examples of the fluorinated monomers include vinyl fluoride, trifluoroethylene (TrFE), chlorofluoroethylene (CTFE), 1,2-difluoroethylene, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), and perfluoro(propyl vinyl) ether (PPVE), perfluoro(1,3-dioxole), and perfluoro(2,2-dimethyl-1,3-dioxole) (PDD), and one or more of these may be included.

[0126] In one embodiment of the present invention, the first porous coating layer and the second porous coating layer may have the same composition, but may be formed with different compositions as needed, and the present invention is not limited thereto.

[0127] In one embodiment of the present invention, the binder in the porous coating layer is the same as or different from the binder in the insulating coating portion, i.e., the first adhesive binder and / or the second adhesive binder, and can be selected independently of these.

[0128] According to yet another aspect of the present invention, an electrochemical element can be provided in which the above-described electrode assembly is housed in a case.

[0129] In one embodiment of the present invention, the case can be one that is commonly used as a battery case and is not particularly limited to an external shape that is appropriate for the battery's application. For example, the case may be cylindrical, rectangular, pouch-type, or coin-type using a can.

[0130] Once the electrode assembly described above is completed, it can be stored in a case and sealed using conventional methods to manufacture an electrochemical element, which in this case may be, for example, a lithium secondary battery.

[0131] On the other hand, an adhesive insulating coating portion may be provided on the separation membrane to improve the adhesion between the separation membrane and the electrode or to prevent short circuits between the electrodes. However, in this case, when providing the adhesive insulating coating portion on the separation membrane, the coating liquid may be impregnated into the pores of the separation membrane and block the pores, which may cause a problem in which the air permeability of the separation membrane is reduced. For this reason, according to one aspect of the present invention, it is desirable to provide the insulating coating portion on the active material layer of the electrode in contact with the separation membrane as described above, and then laminate the separation membrane.

[0132] According to one embodiment of the present invention, when the above-described coating liquid is applied to a separation membrane, the coating liquid may impregnate the pores on the surface of the separation membrane, reducing the permeability of the separation membrane. This may result in a permeability time exceeding 200 seconds / 100cc, potentially making it unsuitable for use as a separation membrane for electrochemical elements. Here, the permeability time may be a value measured using a Garre-Densometer in accordance with the ASTM D726-94 standard. Specifically, the permeability is measured by passing 100cc of air through 1 inch of the separation membrane under measurement at a pressure of 12.2 in H2O. 2 It can be measured as the time (in seconds) it takes for air to pass through the cross-section, i.e., the ventilation time.

[0133] In an electrode assembly manufactured according to one embodiment of the present invention, the separation membrane represents an air permeability time of 200 seconds / 100cc or less, specifically, an air permeability time of 150 seconds / 100cc or less, or 100 seconds / 100cc or less, but the present invention is not limited thereto.

[0134] Thus, according to another aspect of the present invention, a method for manufacturing the electrode assembly described above can be provided.

[0135] A method for manufacturing an electrode assembly according to another aspect of the present invention is: The steps include preparing a current collector and an electrode having an active material layer on at least one surface of the current collector, The steps include forming an insulating coating portion containing inorganic particles and a binder around the entire outer periphery of one surface of the active material layer, The process includes the step of bringing a separation film into contact with the surface on which the insulating coating portion is formed, and then rolling it.

[0136] As described above, the electrode on which the insulating coating portion is formed may be at least one of the positive electrode and the negative electrode.

[0137] Furthermore, the electrode assembly manufactured as described above may have a wet adhesion strength of 1 gf / 20 mm to 20 gf / 20 mm between the electrode on which the insulating coating is formed and the separation film.

[0138] The present invention will be further described below with reference to embodiments, but these embodiments are for illustrative purposes only and the scope of the present invention is not limited to them.

[0139] [Manufacturing of insulating coating compositions] Example 1 Al2O3(D) is added to water (H2O) as inorganic particles. 50 An insulating coating composition was prepared by adding 80 parts by weight of (500 nm) and 20 parts by weight of binder and stirring.

[0140] The aforementioned binder is a first adhesive binder (acrylic, D) with a Tg of 50°C. 50 (400nm) and a second adhesive binder (acrylic, D) with a Tg of -20℃. 50 A mixture of (200 nm) and (200 nm) in a weight ratio of 8:2 was used.

[0141] Example 2 An insulating coating composition was prepared in the same manner as in Example 1, except that the first adhesive binder was changed to an acrylic binder with a Tg of 70°C, and the second adhesive binder was changed to an acrylic binder with a Tg of -40°C.

[0142] Comparative Example 1 An insulating coating composition was prepared in the same manner as in Example 1, except that a first adhesive binder with a Tg of 50°C was used alone as the binder.

[0143] Comparative Example 2 An insulating coating composition was prepared in the same manner as in Example 1, except that a second adhesive binder with a Tg of -20°C was used alone as the binder.

[0144] Comparative Example 3 An insulating coating composition was prepared in the same manner as in Example 1, except that the first adhesive binder was changed to an acrylic binder with a Tg of 40°C, and the second adhesive binder was changed to an acrylic binder with a Tg of 30°C.

[0145] [Manufacturing Example 1: Manufacturing of Electrode Assemblies] An electrode assembly was manufactured using the insulating coating composition produced above, as follows.

[0146] First, the positive electrode active material (LiNi 0.8 Mn 0.1 Co 0.1A slurry for the positive electrode active material layer was prepared by mixing O2), a conductive material (carbon black), a dispersant, and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and removing the water to obtain a slurry with a concentration of 50 wt% of the remaining components. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to form a positive electrode active material layer (thickness 120 μm). By applying each of the insulating coating compositions prepared above around the outer periphery of one surface of the manufactured positive electrode active material layer and drying, a positive electrode was manufactured that had an insulating coating portion (thickness 1 μm) formed around the entire outer periphery of the active material layer (the total area of ​​the insulating coating portion was 17 area % based on the total area of ​​one surface of the positive electrode active material layer).

[0147] A slurry for the negative electrode active material layer was prepared by mixing graphite (a blend of natural and artificial graphite), a conductive material (carbon black), a dispersant, and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and then removing the water to obtain a slurry with a concentration of 50 wt% of the remaining components. Next, the slurry was applied to the surface of a copper thin film (10 μm thick) and dried to produce a negative electrode having a negative electrode active material layer (120 μm thick).

[0148] The positive electrode and negative electrode were placed facing each other, and a polyethylene separation membrane with a thickness of 16 μm and a porosity of 46 vol% was interposed between them to prepare the electrode assembly.

[0149] [Adhesion strength evaluation] For each of the electrode assemblies manufactured as described above, the wet adhesion strength, dry adhesion strength, and peel strength were evaluated using the following method, and the results are shown in Table 1 below. Table 1 below also summarizes the glass transition temperature characteristics of the binders used to form the insulating coating.

[0150] Wet adhesion The positive electrode and separation membrane manufactured as described above were cut to a size of 25 mm x 60 mm, and then pressurized with a heat press at 60°C and a pressure of 6.5 MPa for 1 second. The positive electrode and separation membrane assembly was then placed in a pouch-type case, and 1 g of electrolyte with a composition of 1,3-dioxolane:dimethoxymethane (DOL:DME 1:1 v / v) mixed solvent in which 1 M LiPF6 was dissolved was injected. An aging process and a degassing process were then performed for 1 day.

[0151] Subsequently, the positive electrode and separation membrane assembly were removed from the case and mounted on a UTM device (LLOYD Instrument LF Plus). A force was applied at a measurement speed of 300 mm / min and a 90° angle to measure the force required to separate the bonded surfaces.

[0152] Dry adhesive strength The positive electrode and separation membrane manufactured as described above were cut to a size of 25 mm x 60 mm, and then pressed with a heat press at 60°C and a pressure of 6.5 MPa for 1 second. After that, they were mounted on a UTM device (LLOYD Instrument LF Plus), and force was applied at a measurement speed of 300 mm / min and 180° to measure the force required to separate the bonded surfaces.

[0153] Peel strength The positive electrode manufactured as described above was cut to a size of 15 mm x 100 mm. Double-sided adhesive tape was attached to a glass plate, and the prepared positive electrode was attached so that the insulating coating portion and the surface of the active material layer were adhered to the adhesive tape. Then, the end of the adhered insulating coating portion was attached to a UTM device (LLOYD Instrument LF Plus), and force was applied at a measurement speed of 300 mm / min at a 180° angle to measure the force required to peel the insulating coating portion from the active material layer.

[0154] [Table 1]

[0155] As shown in the results in Table 1 above, when the insulating coating is formed around the entire outer periphery of the positive electrode active material layer, it was confirmed that when two types of adhesive binders are used—a first adhesive binder with a Tg of 50°C or higher and a second adhesive binder with a Tg of 20°C or lower—a wet adhesive strength in the range of 1gf / 20mm to 20gf / 20mm can be achieved. In particular, in Example 1, which used binders with a glass transition temperature difference of 100°C or less, it was confirmed that not only the wet adhesive strength but also the dry adhesive strength and peel strength were superior to those of Comparative Examples 1 to 3.

[0156] On the other hand, in Comparative Example 3, which used two binders with different glass transition temperatures as binders for the insulating coating (using binders with glass transition temperatures of 40°C and 30°C, respectively), it was confirmed that the adhesion strength (peel strength) of the insulating coating was inferior, and both the wet adhesion strength and dry adhesion strength were also inferior. Furthermore, in Comparative Example 1, which used only one type of binder with a Tg of 50°C, the peel strength, wet adhesion strength, and dry adhesion strength of the insulating coating were all inferior. In Comparative Example 2, which used only one type of binder with a Tg of -20°C, it was confirmed that while the adhesion strength of the insulating coating was strong, the wet adhesion strength and dry adhesion strength were not ensured. From this, it was inferred that in Comparative Example 2, the binder was impregnated between the inorganic particles, increasing the adhesion strength of the insulating coating, but the surface adhesion strength of the insulating coating was not ensured.

[0157] [Comparative Manufacturing Example 1: Manufacturing of Electrode Assemblies] Using the insulating coating composition of Example 1 produced above, the positive electrode, negative electrode, and separator film produced in Production Example 1 were prepared in the same manner.

[0158] However, instead of forming an insulating coating portion on the positive electrode, a separation membrane with an insulating coating portion on one surface was prepared by applying the insulating coating composition of Example 1 to one surface of a separation membrane (thickness 16 μm, porosity 46 vol%) that comes into contact with the positive electrode and drying it.

[0159] An electrode assembly was manufactured by stacking the positive electrode, separation membrane, and negative electrode so that the insulating coating portion of the prepared separation membrane faced the positive electrode.

[0160] The electrode assembly prepared according to Comparative Manufacturing Example 1 was found to have a dramatically reduced pore size in the separation membrane and was deemed unsuitable for use as an electrochemical element. Specifically, when the air permeability of the separation membrane with an insulating coating was evaluated as follows, it was confirmed that the air permeability time of the separation membrane exceeded 200 s / 100 cc.

[0161] Measurement of air permeability (air permeability time) Air permeability was measured using a Garre-Densometer in accordance with the ASTM D726-94 standard. Specifically, the air permeability was measured by passing 100 cc of air through 1 inch of the separation membrane under measurement at a pressure of 12.2 in H2O. 2 The time (in seconds) it takes for air to pass through the cross-section was measured as the airflow time.

[0162] As described above with reference to embodiments and drawings of the present invention, any person with ordinary skill in the art to which the present invention belongs should be able to make various applications and modifications within the scope of the present invention based on the above description. [Explanation of Symbols]

[0163] 1: Electrode tab section 10: Current collector 11: Electrode active material layer 20: Insulating coating section 30: Separation membrane

Claims

1. An electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane interposed between the positive electrode and the negative electrode, At least one of the positive electrode and the negative electrode includes a current collector, an active material layer formed on at least one surface of the current collector, and an insulating coating portion formed around the entire outer periphery of one surface of the active material layer. An electrode assembly in which the wet adhesion force between the positive or negative electrode provided with the insulating coating portion and the separation film is 1 gf / 20 mm to 20 gf / 20 mm.

2. The electrode assembly according to claim 1, wherein at least one of the positive electrode and the negative electrode includes an active material layer and an insulating coating portion formed around the entire outer circumference of one surface of the current collector, respectively, on both surfaces of the current collector.

3. The insulating coating portion comprises inorganic particles and a binder. The electrode assembly according to claim 1, wherein the binder comprises two adhesive binders having a difference in glass transition temperature (Tg) of 100°C or less.

4. The insulating coating portion comprises inorganic particles and a binder. The aforementioned binder is, A first adhesive binder having a glass transition temperature (Tg) of 50°C or higher, The electrode assembly according to claim 1, comprising a second adhesive binder having a glass transition temperature (Tg) of 20°C or less.

5. It contains inorganic particles and a binder. The aforementioned binder is an insulating coating composition comprising two adhesive binders having a difference in glass transition temperature (Tg) of 100°C or less.

6. It contains inorganic particles and a binder. The aforementioned binder is, A first adhesive binder having a glass transition temperature (Tg) of 50°C or higher, An insulating coating composition comprising a second adhesive binder having a glass transition temperature (Tg) of 20°C or less.

7. The insulating coating composition according to claim 6, wherein the first adhesive binder comprises an aqueous particulate binder.

8. The insulating coating composition according to claim 7, wherein the first adhesive binder comprises an aqueous particle-type binder with a particle size of 250 nm or more.

9. The insulating coating composition according to claim 6, wherein the second adhesive binder comprises an aqueous particulate binder, a solution binder, or a mixture thereof.

10. The insulating coating composition according to claim 9, wherein the second adhesive binder comprises an aqueous particle-type binder with a particle size of 250 nm or less.

11. The insulating coating composition according to claim 6, wherein the weight ratio of the first adhesive binder and the second adhesive binder is 1:9 to 9:

1.

12. The insulating coating composition according to claim 5 or 6, wherein the weight ratio of the inorganic particles to the binder is 7:3 to 9:

1.

13. An electrochemical element in which the electrode assembly according to any one of claims 1 to 4 is housed in a case.

14. The steps include preparing a current collector and an electrode having an active material layer on at least one surface of the current collector, The steps include forming an insulating coating portion containing inorganic particles and a binder around the entire outer periphery of one surface of the active material layer, The step includes bringing a separation film into contact with the surface on which the insulating coating portion is formed, and then rolling it, The electrode is at least one of a positive electrode and a negative electrode. A method for manufacturing an electrode assembly, wherein the wet adhesion between the electrode on which the insulating coating portion is formed and the separation film is 1 gf / 20 mm to 20 gf / 20 mm.

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