Separator, method of manufacturing the same, and electrode assembly including the same

Abstract

This invention relates to a diaphragm, a method of manufacturing the diaphragm, and an electrode assembly including the diaphragm. According to one aspect, the diaphragm may include: a substrate; and a coating formed on at least one side of the substrate, wherein the coating may comprise an inorganic material and a first adhesive, the first adhesive having a glass transition temperature of 100°C or less, and the diaphragm may satisfy the following formula 1: [Formula 1] 1.2 ≤ D B1 / T C ≤2.0 in Equation 1, D B1 D50 is the particle diameter (D50) when the cumulative particle size distribution of the first adhesive reaches 50% by volume, and its unit is μm. C The thickness of the coating is expressed in μm.

Description

Technical Field

[0001] The present invention relates to a diaphragm, a method for manufacturing the diaphragm, and an electrode assembly including the diaphragm. Background Technology

[0002] As the application scope of secondary batteries continues to expand, the demand for larger area and higher capacity is increasing. In addition, secondary batteries are generally composed of a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. In order to impart functionality to the porous thin film separator (containing polymers or non-woven fabrics) that is usually used as the separator, various methods are being explored.

[0003] As an example of such an attempt, efforts to improve battery performance by forming a fusion layer on at least one side of the separator and fusing it with the electrodes can be cited. With the rapid increase in battery capacity, the area of ​​the electrodes used is also rapidly expanding. In the case of batteries as described above, as charge-discharge cycles proceed, gaps appear between the electrodes that are not adhered to each other, or the battery swells or deforms, resulting in a deterioration in lifespan characteristics. Therefore, by forming a fusion layer on at least one side of the separator, gaps, swelling, or deformation between the electrodes can be prevented, thereby improving lifespan characteristics. Furthermore, it can also improve electrode misalignment (i.e., poor electrode alignment) that occurs when stacking a large number of electrodes to assemble them into an electrode assembly.

[0004] As an example of other attempts, one can cite attempts to improve the structural stability of the substrate by forming a heat-resistant layer on at least one side of the diaphragm. Previously, materials used as diaphragm substrates were mainly produced by stretching. Due to residual shrinkage stress in the stretching direction, shrinkage occurs when the temperature rises. Therefore, by using materials with excellent mechanical rigidity and thermal stability, such as inorganic materials, to form a heat-resistant layer, the mechanical, structural, and thermal stability of the diaphragm can be improved.

[0005] As a fusion of the above-mentioned attempts, research is underway to simultaneously achieve a heat-resistant layer and a fusion layer. This research primarily attempts to introduce a fusion layer further onto the heat-resistant layer. However, when the fusion layer becomes too thick, the migration distance of ions increases, leading to an increase in internal resistance. Therefore, efforts are being made to set the thickness of the fusion layer to be as thin and uniform as possible. However, with the attempts described above, it is difficult to achieve the target level of fusion performance, and the binder contained in the fusion layer swells in the electrolyte, clogging the pores of the separator, thus causing problems such as increased battery resistance or decreased safety. Therefore, there is a current need for a separator that can achieve an excellent level of fusion performance while appropriately adjusting the amount of binder contained in the fusion layer. Summary of the Invention

[0006] (a) Technical problems to be solved According to one aspect of the invention, a diaphragm can be provided that achieves sufficient fusion force while minimizing the amount of adhesive used for fusion between the electrode and the diaphragm, and has excellent mechanical stability, structural stability and thermal stability.

[0007] According to another aspect of the present invention, a method for manufacturing a diaphragm can be provided, the method having excellent processability and manufacturing economy.

[0008] According to another aspect of the present invention, an electrode assembly can be provided, wherein the electrode and the diaphragm of the electrode assembly have excellent fusion force, and the electrode assembly has excellent resistance characteristics, life characteristics, safety, mechanical stability, structural stability and thermal stability.

[0009] According to another aspect of the present invention, a method for manufacturing an electrode assembly can be provided, the method having excellent processability and manufacturing economy.

[0010] Furthermore, this invention can be widely applied to green technologies such as electric vehicles, battery charging stations, energy storage systems (ESS), and other battery-based solar and wind power generation. In addition, this invention can be used for eco-friendly mobility, including electric vehicles and hybrid vehicles, to prevent climate change by suppressing air pollution and greenhouse gas emissions.

[0011] (II) Technical Solution The diaphragm according to the present invention may include: a substrate; and a coating formed on at least one side of the substrate, wherein the coating may contain an inorganic material and a first adhesive, the glass transition temperature of the first adhesive may be below 100°C, and the diaphragm may satisfy the following formula 1.

[0012] [Formula 1] 1.2≤D B1 / T C ≤2.0 In Equation 1, D B1 D50 is the particle diameter (D50) when the cumulative particle size distribution of the first adhesive reaches 50% by volume, and its unit is μm. CThe thickness of the coating is expressed in μm.

[0013] In a diaphragm according to one embodiment, the following equation 2 can also be satisfied.

[0014] [Equation 2] 1.4≤D B1 / T C ≤1.8 In Equation 2, D B1 and T C The definition is the same as the definition above.

[0015] In a diaphragm according to one embodiment, at least a portion of the first adhesive may be exposed to the outside while in contact with the substrate.

[0016] In a diaphragm according to one embodiment, the substrate may comprise at least one of a porous polymer and a porous nonwoven fabric.

[0017] In a diaphragm according to one embodiment, the glass transition temperature of the first adhesive can be from 40°C to 60°C.

[0018] In a diaphragm according to one embodiment, the D B1 It can be above 1.2μm.

[0019] In a diaphragm according to one embodiment, the first adhesive may comprise: at least one selected from polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), polybutyl acrylate (PBA), polyethylhexyl acrylate (PEHA), styrene-butadiene rubber (SBR), and polyethylene oxide (PEO); or copolymers of any two or more of them.

[0020] In a diaphragm according to one embodiment, the T C It can range from 1μm to 20μm.

[0021] In one embodiment of the diaphragm, the coating may further comprise a second adhesive.

[0022] In a diaphragm according to one embodiment, the coating may comprise the inorganic material and the second adhesive in a weight ratio of 60 to 99:40 to 1.

[0023] In a diaphragm according to one embodiment, the content of the first adhesive may be from 1% by weight to 30% by weight relative to the total weight of the inorganic material and the second adhesive.

[0024] The method for manufacturing a diaphragm according to the present invention is a method for manufacturing a diaphragm according to the present invention, the manufacturing method may include the following steps: preparing a substrate; applying a diaphragm coating slurry to at least one side of the substrate; and curing the applied diaphragm coating slurry to form a coating on at least one side of the substrate, wherein the diaphragm coating slurry may contain the inorganic material and the first adhesive.

[0025] In a method of manufacturing a diaphragm according to one embodiment, the diaphragm coating slurry may further include a second adhesive.

[0026] In a method of manufacturing a diaphragm according to one embodiment, the content of the first adhesive in the diaphragm coating slurry can be from 1% by weight to 30% by weight relative to the total weight of the inorganic material and the second adhesive.

[0027] The electrode assembly according to the present invention may include: a positive electrode; a negative electrode; and a diaphragm according to the present invention, the diaphragm being disposed between the positive electrode and the negative electrode, wherein at least a portion of the first adhesive may simultaneously contact the substrate and the positive electrode, or simultaneously contact the substrate and the negative electrode.

[0028] (III) Beneficial Effects According to one aspect of the invention, a diaphragm can be provided that achieves sufficient fusion force while minimizing the amount of adhesive used for fusion between the electrode and the diaphragm, and has excellent mechanical stability, structural stability and thermal stability.

[0029] According to another aspect of the present invention, a method for manufacturing a diaphragm can be provided, the method having excellent processability and manufacturing economy.

[0030] According to another aspect of the present invention, an electrode assembly can be provided, wherein the electrode and the diaphragm of the electrode assembly have excellent fusion force, and the electrode assembly has excellent resistance characteristics, life characteristics, safety, mechanical stability, structural stability and thermal stability.

[0031] According to another aspect of the present invention, a method for manufacturing an electrode assembly can be provided, the method having excellent processability and manufacturing economy.

[0032] Furthermore, this invention can be widely applied to green technology fields such as electric vehicles, battery charging stations, energy storage devices (ESS systems), and other battery-powered solar and wind power generation. In addition, this invention can be used for environmentally friendly mobility, including electric and hybrid vehicles, to prevent climate change by suppressing air pollution and greenhouse gas emissions. Attached Figure Description

[0033] Figure 1 A diagram illustrating an example of a diaphragm according to one embodiment of the present invention.

[0034] Figure 2 A step diagram illustrating an example of a method for manufacturing a diaphragm according to an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures: 100: Diaphragm 110: Substrate 120: Coating 121: Inorganic substances 122: First Adhesive 123: Second adhesive Detailed Implementation

[0036] The embodiments described in this specification can be modified in various different forms, and therefore the technology according to a particular embodiment is not limited to the embodiment described below. Furthermore, throughout the specification, unless otherwise specifically stated to the contrary, "comprising," "including," "possessing," "containing," or "having" a constituent element means that other constituent elements may also be included, and does not exclude other constituent elements, nor does it exclude elements, materials, or processes not further listed.

[0037] In this specification, unless otherwise stated, "identical" or "uniform" can mean that they are identical or uniform to each other within an acceptable margin of error. As an example, "identical" in terms of a constituent or physical property measurement can mean not only that the two objects being compared are completely identical, but also that they are identical within a margin of error. Furthermore, "identical" in terms of a physical property measurement can mean that the difference between the measurements of the objects is approximately less than 5%, specifically less than 3%, and more specifically less than 1%.

[0038] In this specification, the angle between two objects being perpendicular, parallel to each other, or side by side can include not only geometrically perpendicular or parallel, but also cases within a small margin of error.

[0039] The numerical ranges used in this specification include lower and upper limits, as well as all values ​​within that range, increments logically derived from the form and width of the defined range, all values ​​defined therein, and all possible combinations of upper and lower limits of numerical ranges defined in different forms from each other.

[0040] In this specification, unless otherwise specifically defined, “about” can be considered as a value within 30%, 25%, 20%, 15%, 10%, or 5% of the explicitly stated value.

[0041] In this specification, the terms "first," "second," "third," etc., used before any constituent element are only for the purpose of avoiding confusion regarding the constituent element being represented, and are unrelated to the order, importance, or hierarchical relationship between the constituent elements. For example, an invention that includes only the second constituent element but not the first constituent element can also be realized.

[0042] The terms “D10”, “D50” or “D90” used in this specification can refer to the particle diameter at which the cumulative volume, starting from the smallest particle size, reaches 10%, 50%, and 90%, respectively, in particle size distribution measurements by laser scattering.

[0043] As used in this specification, the term "secondary battery" can refer to a battery that generates electrical energy through oxidation and reduction reactions during the insertion and extraction of metal ions (specifically, cations such as lithium ions) into and out of the positive and negative electrodes. Specifically, "secondary battery" can refer to any one of the following: lithium-cobalt battery, lithium-nickel battery, lithium iron phosphate battery, lithium-ion battery, lithium polymer battery, lithium-sulfur battery, nickel-metal hydride battery, nickel-cadmium battery, sodium battery, and all-solid-state battery. More specifically, the term "secondary battery" as used in this specification can refer to a lithium-ion secondary battery, but is not necessarily limited to this.

[0044] The present invention will now be described in detail. However, this is merely an exemplary description, and the present invention is not limited to the specific embodiments described herein.

[0045] diaphragm Figure 1 A diagram illustrating an example of a diaphragm according to one embodiment of the present invention.

[0046] Reference Figure 1 According to one aspect of the present invention, a diaphragm 100 may include: a substrate 110; and a coating 120 formed on at least one side of the substrate 110, wherein the coating 120 may include an inorganic material 121 and a first adhesive 122, the glass transition temperature of the first adhesive 122 may be below 100°C, and the diaphragm 100 may satisfy the following formula 1.

[0047] [Formula 1] 1.2≤D B1 / T C ≤2.0 In Equation 1, D B1 The particle diameter (D50) is the particle size distribution of the first adhesive 122 when its volume fraction is 50%, and its unit is μm. C The thickness of the coating 120 is expressed in μm.

[0048] In a specific implementation plan, the D B1 / T C Values ​​can be 1.21 or higher, 1.22 or higher, 1.23 or higher, 1.24 or higher, 1.25 or higher, 1.26 or higher, 1.27 or higher, 1.28 or higher, 1.29 or higher, 1.3 or higher, 1.31 or higher, 1.32 or higher, 1.33 or higher, 1.34 or higher, 1.35 or higher, 1.36 or higher, 1.37 or higher, 1.38 or higher, or 1.39 or higher, or values ​​below 1.99, 1.98, 1.97, 1.96, 1.95, 1.94, 1.93, 1.92, 1.91, 1.90, 1.89, 1.88, 1.87, 1.86, 1.85, 1.84, 1.83, 1.82 or lower.

[0049] In one embodiment, the diaphragm 100 may also satisfy the following formula 2.

[0050] [Equation 2] 1.4≤D B1 / T C ≤1.8 In Equation 2, D B1 and T C The definition is the same as the definition above.

[0051] Reference Figure 1 In one embodiment, at least a portion of the first adhesive 122 may be exposed to the outside while in contact with the substrate 110.

[0052] Additionally, in an exemplary embodiment, all of the first adhesive 122 may be in contact with the substrate 110 while at least a portion is exposed to the outside.

[0053] In the embodiments described above, the D50 value of the first adhesive 122 may be greater than the thickness of the coating 120. In the embodiments described above, at least a portion of the first adhesive 122 may contact the substrate 110 on one side, and at least a portion of the remaining portion other than said one side may be exposed to the outside. That is, in the embodiments described above, the portion exposed to the outside can be defined as the portion of the first adhesive 122 protruding from the surface of the coating 120. The definition described above can apply to all cases where at least a portion of the first adhesive 122 is disposed in the coating 120 in the manner described above, or where all of the first adhesive 122 is disposed in the coating 120 in the manner described above.

[0054] Additionally, when the DB1 / T C When the value is less than the above-mentioned range, the effect of the first adhesive 122, which has thermal fusion properties, on improving the fusion force between the diaphragm 100 and the electrode may not be significant during the manufacture of the electrode assembly. B1 / T C When the value exceeds the above range, the size of the first adhesive 122 may be too large, which may reduce the adhesion between the separator 100 and the electrode interface during the manufacturing of the electrode assembly, thereby potentially causing a decrease in battery performance and safety.

[0055] in addition, Figure 1 The shapes, sizes, colors, thicknesses, shadows, widths, etc. of the constituent elements shown are arbitrarily illustrated for ease of explanation and can be configured in various ways as needed without departing from the scope defined in this invention. It is only natural that the scope of the claims is not limited as a result.

[0056] Refer again Figure 1 In one embodiment, the diaphragm 100 may include a substrate 110.

[0057] In one embodiment, the substrate 110 may be configured to allow ion flow while preventing physical short circuits between electrodes. Additionally, the diaphragm 100 may be made of a material that is fusible when exposed to high temperatures.

[0058] In one embodiment, the substrate 110 may comprise at least one of a porous polymer and a porous nonwoven fabric.

[0059] In an exemplary embodiment, the porous polymer membrane may comprise polyolefin-based polymers such as ethylene polymers, propylene polymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers. The porous nonwoven fabric may comprise high-melting-point glass fibers, polyethylene terephthalate fibers, etc. Furthermore, the diaphragm may have a single-layer or multi-layer structure comprising the aforementioned polymer membrane and / or nonwoven fabric.

[0060] In one embodiment, the thickness of the substrate 110 can be from 1 μm to 100 μm. In a specific embodiment, the thickness of the substrate 110 can be 2 μm or more, 3 μm or more, or 4 μm or more, or it can be less than 90 μm, 80 μm or less, 70 μm or less, 60 μm or less, or 50 μm or less. In an exemplary embodiment, the thickness of the substrate 110 can be from 5 μm to 30 μm, but is not necessarily limited to this.

[0061] In one embodiment, the coating 120 may be formed on at least one side of the substrate 110. In an exemplary embodiment, the coating 120 may be formed on only one side of the substrate 110 or on both sides of the substrate 110.

[0062] In one embodiment, the coating 120 may comprise an inorganic material 121.

[0063] In one embodiment, the inorganic material 121 may be contained in the coating 120 in the form of particles. Furthermore, the inorganic material 121 is rigid and does not deform under external impact or force, or only a minute degree of deformation is observed. Additionally, the inorganic material 121 may exhibit high thermal stability and / or high chemical stability, thus no thermal deformation is observed at high temperatures, or only a minute degree of deformation is observed, and no side reactions with components within the secondary battery, such as the electrolyte, are observed, or only a minute degree of reaction is observed.

[0064] By including inorganic material 121 in the coating 120 as described above, the substrate 110 can be prevented from thermally shrinking in high-temperature environments, while the heat resistance and chemical stability of the separator 100 can be improved, thereby improving the stability and safety of the battery and improving the electrical characteristics of the battery.

[0065] In one embodiment, the particle size of the inorganic material 121 can be from 0.1 μm to 2.0 μm, but is not necessarily limited to this. Alternatively, the particle size can refer to the D50 value based on the cumulative particle size distribution as described above.

[0066] In the implementation described above, 0.1μm≤D can be satisfied. I The relationship is ≤2.0μm, where D I This can refer to the particle size of the inorganic material 121.

[0067] In one embodiment, the inorganic material 121 may comprise at least one selected from alumina, boehmite, aluminum hydroxide, titanium oxide, magnesium oxide, magnesium hydroxide, silicon oxide, clay, and glass powder.

[0068] In one embodiment, the coating 120 may include a first adhesive 122.

[0069] In one embodiment, when heat is applied within a predetermined temperature range, at least a portion of the first adhesive 122 may melt, undergo a phase change, or at least undergo a partial change in physical properties. When the temperature returns to normal or at least the application of heat within the aforementioned temperature range is stopped, the bonding or fusion force on the contacting components can be ensured.

[0070] That is, in the embodiments described above, the first adhesive 122 may have thermal fusion properties.

[0071] In another embodiment, the first adhesive 122 may be flexible.

[0072] By including a first adhesive 122 in the coating 120 as described above, a bonding or fusion force can be imparted between the diaphragm 100 and the electrodes in an electrode assembly according to one aspect, which includes electrodes (including positive and negative electrodes) and a diaphragm 100.

[0073] In one embodiment, the glass transition temperature (Tg) of the first adhesive 122 may be below 100°C.

[0074] In one embodiment, the glass transition temperature of the first adhesive 122 can be from 40°C to 60°C. When the glass transition temperature of the first adhesive 122 is below the above-mentioned range, it becomes too sticky and sticks together when wound into a roll, making it difficult to unroll and use. When the glass transition temperature of the first adhesive 122 exceeds the above-mentioned range, the following problem arises: when performing the following thermal fusion by applying heat within a temperature range (80°C to 100°C) that will not cause thermal deformation of the substrate 110 of the diaphragm, the bonding strength or fusion strength cannot be sufficiently ensured.

[0075] In a specific implementation, the glass transition temperature of the first adhesive 122 can be from 45°C to 55°C.

[0076] In one implementation, the D B1 It can be above 1.2μm.

[0077] In a specific implementation plan, the D B1 It can range from 1.2μm to 40μm.

[0078] When the D B1 When the value is less than the above-mentioned range, the effect of the first adhesive 122, which has thermal fusion properties, on improving the fusion force between the diaphragm 100 and the electrode may not be significant during the manufacture of the electrode assembly. B1 When the value exceeds the above range, the size of the first adhesive 122 may be too large, which may reduce the adhesion between the separator 100 and the electrode interface during the manufacturing of the electrode assembly, thereby potentially causing a decrease in battery performance and safety.

[0079] In one embodiment, the first adhesive 122 may comprise at least one selected from polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), polybutyl acrylate (PBA), polyethylhexyl acrylate (PEHA), styrene-butadiene rubber (SBR), and polyethylene oxide (PEO); or copolymers of any two or more of these.

[0080] Refer again Figure 1 In one implementation, the T C The thickness can be from 1 μm to 20 μm. That is, the thickness of the coating 120 can be from 1 μm to 20 μm. Furthermore, in a specific embodiment, the T... C It can range from 1μm to 10μm.

[0081] Additionally, refer to Figure 1 As shown, the thickness of the coating 120 (i.e., T) C The thickness of the coating 120 can refer to the average thickness of the coating 120 in the area excluding the region formed by the first adhesive 122. Specifically, the thickness of the coating 120 (i.e., T) C () can refer to the average thickness of the coating 120 in the area excluding the area where the first adhesive 122 protrudes.

[0082] In addition, when the thickness of the coating 120 is less than the above-mentioned numerical range, the improvement effect of the heat resistance or rigidity brought about by the formation of the coating 120 may not be obvious. When the thickness of the coating 120 exceeds the above-mentioned numerical range, problems such as deterioration of the battery's electrical characteristics or deterioration of its processability may occur.

[0083] Refer again Figure 1In one embodiment, the coating 120 may further include a second adhesive 123.

[0084] In one embodiment, the inclusion of the second adhesive 123 may be intended for bonding between the inorganic material 121 and the substrate 110 within the coating 120, or for bonding between the inorganic materials 121. That is, in the embodiment described above, the primary purpose of including the first adhesive 122 may be to ensure the bonding force between the diaphragm 100 and the electrode in the electrode assembly described above, and the primary purpose of including the second adhesive 123 may be to bond between the inorganic material 121 and the substrate 110 within the coating 120 and / or to the inorganic materials 121 bond with each other. However, this is not necessarily the case; the first adhesive 122 may also partially participate in the bonding between the inorganic material 121 and the substrate 110 or the bonding between the inorganic materials 121, and the second adhesive 123 may also partially participate in ensuring the bonding force between the diaphragm 100 and the electrode.

[0085] In one embodiment, more than 90% by weight of the second adhesive 123 contained in the coating 120 may not be exposed to the outside. In specific embodiments, more than 91% by weight, more than 92% by weight, more than 93% by weight, more than 94% by weight, more than 95% by weight, more than 96% by weight, more than 97% by weight, more than 98% by weight, more than 99% by weight, or more than 99.9% by weight of the second adhesive 123 may not be exposed to the outside.

[0086] In one embodiment, the second adhesive 123 may comprise at least one of an acrylic polymer, a cellulose polymer, and a butadiene polymer, but is not necessarily limited thereto. Any adhesive available in the art for interparticle bonding may be used without limitation, as needed.

[0087] In one embodiment, the weight ratio of the inorganic material 121 to the second adhesive 123 can be 60 to 99:40 to 1. That is, in the embodiment described above, the weight ratio of the inorganic material 121 to the second adhesive 123 contained in the coating 120 can be 60:40 to 99:1.

[0088] When the content of the inorganic material 121 is less than the above weight ratio, the content of the second binder 123 becomes too high, and the gaps formed between the inorganic material 121 particles are reduced. This leads to a decrease in porosity and pore size, which may result in a deterioration of battery characteristics. When the content of the inorganic material 121 exceeds the above weight ratio, the bonding force between the inorganic materials 121 or the bonding force between the inorganic materials 121 and the substrate 110 is reduced, which may result in a decrease in the structural stability of the separator 100.

[0089] In one embodiment, the content of the first adhesive 122 may be from 1% to 30% by weight relative to the total weight of the inorganic material 121 and the second adhesive 123. That is, in one embodiment, the content of the first adhesive 122 in the coating 120 may be from 1% to 30% by weight relative to the total weight of the solids of the inorganic material 121 and the second adhesive 123.

[0090] In a specific implementation, relative to the total weight mentioned above, the content of the first adhesive 122 can be 1.3% by weight or more, 1.5% by weight or more, 1.7% by weight or more, 2% by weight or more, 2.2% by weight or more, or 2.5% by weight or less, or less than 29% by weight, less than 28% by weight, less than 27% by weight, less than 26% by weight, or less than 25% by weight.

[0091] When the content of the first adhesive 122 is less than the above-mentioned numerical range, the effect of the first adhesive 122 in ensuring the bonding or fusion force between the separator 100 and the electrode may not be obvious. When the content of the first adhesive 122 exceeds the above-mentioned numerical range, although a high degree of bonding or fusion force can be ensured, the swelling of the first adhesive 122 in the electrolyte may lead to pore blockage, increased battery resistance and deterioration of safety, and may also lead to deterioration of processability and manufacturing economy.

[0092] In a specific implementation, the content of the first adhesive 122 may be from 5% to 20% by weight relative to the total weight of the inorganic material 121 and the second adhesive 123.

[0093] In the embodiments described above, the diaphragm 100 may include a substrate 110 and a coating 120 formed on at least one side of the substrate 110. Additionally, the coating 120 may include an inorganic material 121 and a first adhesive 122, and may further include a second adhesive 123.

[0094] In the embodiment described above, at least a portion of the first adhesive 122 may be exposed to the outside. That is, when the diaphragm 100 is viewed from the outside, at least a portion of the first adhesive 122 may be configured to protrude from the surface of the coating 120. Additionally, in the embodiment described above, at least a portion of the first adhesive 122 exposed to the outside may be in contact with the substrate 110 on the other side.

[0095] In the embodiments described above, the diaphragm 100 can have structural stability, mechanical stability, thermal stability and chemical stability, while exhibiting excellent electrical properties. When forming an electrode assembly, the electrode and the diaphragm 100 can have excellent fusion force or bonding force, and the electrode and the diaphragm 100 interface can have excellent adhesion.

[0096] Method for manufacturing diaphragms Figure 2 A step diagram illustrating an example of a method for manufacturing a diaphragm according to an embodiment of the present invention.

[0097] Reference Figure 2 The method for manufacturing a diaphragm according to one aspect of the present invention is a method for manufacturing a diaphragm according to one aspect of the present invention, the manufacturing method may include the following steps: preparing a substrate (S100); applying a diaphragm coating slurry to at least one side of the substrate (S200); and curing the applied diaphragm coating slurry to form a coating on at least one side of the substrate (S300), wherein the diaphragm coating slurry may contain the inorganic material and the first adhesive.

[0098] In one embodiment, step S100 may refer to the step of preparing a substrate. Furthermore, for a detailed description of the substrate, please refer to... Figure 1 The above explanation also applies, so repeated explanations are omitted below.

[0099] In one embodiment, step S200 may refer to the step of coating at least one side of the substrate prepared in step S100 with a diaphragm coating slurry.

[0100] In one embodiment, the diaphragm coating slurry may comprise the inorganic material and the first adhesive. Further detailed description of the inorganic material and the first adhesive can be found in [reference needed]. Figure 1 The above explanation also applies, so repeated explanations are omitted below.

[0101] The inorganic material and the first binder can be dispersed and mixed in a suitable solvent to prepare the diaphragm coating slurry. In an exemplary embodiment, the solvent may be water, methanol, ethanol, propanol, acetone, tetrahydrofuran, methyl ethyl ketone, ethyl acetate, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, diethylformamide, etc., but is not necessarily limited to these. Any solvent known in the art may be used without restriction, as long as it is suitable for dispersing and dissolving the inorganic material and the first binder.

[0102] In one embodiment, the diaphragm coating slurry may further comprise a second adhesive. For a detailed description of the second adhesive, please refer to [link to relevant documentation]. Figure 1 The above explanation also applies, so repeated explanations are omitted below.

[0103] In one embodiment, the content of the first adhesive in the diaphragm coating slurry may be from 1% to 30% by weight relative to the total weight of the inorganic material and the second adhesive. That is, in one embodiment, the content of the first adhesive in the diaphragm coating slurry may be from 1% to 30% by weight relative to the total weight of the solids of the inorganic material and the second adhesive.

[0104] In a specific implementation, relative to the total weight mentioned above, the content of the first adhesive can be 1.3% by weight or more, 1.5% by weight or more, 1.7% by weight or more, 2% by weight or more, 2.2% by weight or more, or 2.5% by weight or less, or less than 29% by weight, less than 28% by weight, less than 27% by weight, less than 26% by weight, or less than 25% by weight.

[0105] When the content of the first adhesive is less than the above-mentioned numerical range, the effect of the first adhesive in ensuring the bonding or fusion force between the separator and the electrode during coating formation may not be obvious. When the content of the first adhesive exceeds the above-mentioned numerical range, although a high degree of bonding or fusion force can be ensured, the swelling of the first adhesive in the electrolyte may lead to pore blockage, increased battery resistance and deterioration of safety, and may also lead to deterioration of processability and manufacturing economy.

[0106] In a specific implementation, the content of the first adhesive can be from 5% to 20% by weight relative to the total weight of the inorganic material and the second adhesive.

[0107] In one embodiment, step S200 can be performed by methods such as bar coating, gravure coating, dip coating, slot extrusion coating, multi-layer simultaneous die coating, embossing, doctor blade coating, casting, etc., but is not limited to these methods. As needed, appropriate methods known in the art can be used.

[0108] In one embodiment, step S300 may refer to the step of curing the diaphragm coating slurry applied in step S200. Through step S300, the coating can be formed on at least one side of the substrate. Step S300 may include, for example, the step of drying the applied diaphragm coating slurry. The drying can be performed using known drying methods such as blow drying, hot air drying, laser drying, and heat drying, and the drying temperature and time can also be within an appropriate range.

[0109] The method for manufacturing a diaphragm according to one aspect of the present invention uses the manufacturing method described above, thereby simplifying the process and thus improving processability and manufacturing economy compared with the prior art of first coating a heat-resistant layer and drying it before separately coating a heat-fused layer.

[0110] Electrode assembly An electrode assembly according to one aspect of the invention may include: a positive electrode; a negative electrode; and a diaphragm according to one aspect of the invention, the diaphragm being disposed between the positive electrode and the negative electrode, wherein at least a portion of the first adhesive may simultaneously contact the substrate and the positive electrode, or simultaneously contact the substrate and the negative electrode.

[0111] In one embodiment, the positive electrode may include a positive electrode current collector and a layer of positive electrode active material formed on at least one side of the positive electrode current collector.

[0112] In one embodiment, the positive current collector may include a known conductive material within the range that does not cause a chemical reaction within the secondary battery.

[0113] In exemplary embodiments, non-limiting examples of the positive current collector may include stainless steel, nickel, aluminum, titanium, or alloys thereof. The positive current collector may also include aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver. The thickness of the positive current collector may be, for example, from 10 μm to 50 μm, but is not limited thereto.

[0114] In one embodiment, the positive electrode active material layer may comprise a positive electrode active material. The positive electrode active material may comprise a compound that allows for the reversible insertion and extraction of metal ions (specifically lithium ions).

[0115] The positive electrode active material may comprise a lithium-nickel metal oxide. The lithium-nickel metal oxide may further comprise at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0116] In some embodiments, the positive electrode active material or the lithium-nickel metal oxide may comprise a layered structure or a crystal structure represented by the following chemical formula 1.

[0117] [Chemical Formula 1] Li x Ni a M b O 2+z In chemical formula 1, the values ​​can be 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b≤0.4, and -0.5≤z≤0.1. As mentioned above, M can contain Co, Mn, and / or Al.

[0118] The chemical structure represented by Formula 1 indicates the bonding relationships contained in the layered or crystalline structure of the positive electrode active material, and does not exclude other additional elements. For example, M may contain Co and / or Mn, and Co and / or Mn may be provided together with Ni as the main active element of the positive electrode active material. Formula 1 is provided to represent the bonding relationships of the main active elements, and it should be understood that Formula 1 includes the introduction and substitution of additional elements.

[0119] In one embodiment, in addition to the primary active element, auxiliary elements may be further included to enhance the chemical stability of the positive electrode active material or the layered / crystal structure. These auxiliary elements may be incorporated into the layered / crystal structure and form bonds; this should be understood to also include the chemical structures represented by Formula 1.

[0120] The auxiliary element may include at least one of, for example, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr. The auxiliary element may function as an auxiliary active element, together with Co or Mn, to contribute to the capacity / power activity of the positive electrode active material; for example, Al.

[0121] For example, the positive electrode active material or the lithium-nickel metal oxide may contain a layered structure or a crystal structure represented by the following chemical formula 1-1.

[0122] [Chemical Formula 1-1] Li x Ni a M1 b1 M2 b2 O 2+z In chemical formula 1-1, M1 may contain Co, Mn, and / or Al. M2 may contain the aforementioned auxiliary elements. In chemical formula 1-1, the following conditions may be met: 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b1+b2≤0.4, -0.5≤z≤0.1.

[0123] The positive electrode active material may further include coating elements or doping elements. For example, elements that are substantially the same as or similar to the auxiliary elements described above can be used as coating elements or doping elements. For example, one or more combinations of the elements described above can be used as coating elements or doping elements.

[0124] The coating element or doping element may be present on the surface of the lithium-nickel metal oxide particles, or may penetrate through the surface of the lithium-nickel metal oxide particles and be contained in the bonding structure represented by chemical formula 1 or chemical formula 1-1.

[0125] The positive electrode active material may contain nickel-cobalt-manganese (NCM)-based lithium oxide. In this case, NCM-based lithium oxide with increased nickel content can be used.

[0126] Ni can be provided as a transition metal related to the power and capacity of lithium secondary batteries. Therefore, as described above, by using a high-content (High-Ni) composition for the positive electrode active material, a high-capacity positive electrode and a high-capacity secondary battery can be provided.

[0127] However, with increasing Ni content, the long-term storage stability and lifetime stability of the cathode or secondary battery may relatively decrease, and side reactions with the electrolyte may also increase. However, according to an exemplary embodiment, conductivity can be maintained by including Co, while lifetime stability and capacity retention characteristics can be improved by including Mn.

[0128] In the NCM-based lithium oxide, the Ni content (e.g., the mole fraction of nickel in the total moles of nickel, cobalt, and manganese) can be 0.6 or more, 0.7 or more, or 0.8 or more. In some embodiments, the Ni content can be 0.8 to 0.95, 0.82 to 0.95, 0.83 to 0.95, 0.84 to 0.95, 0.85 to 0.95, or 0.88 to 0.95.

[0129] In some embodiments, the positive electrode active material may also include lithium cobalt oxide-based active material, lithium manganese oxide-based active material, lithium nickel oxide-based active material, or lithium iron phosphate (LFP)-based active material (e.g., LiFePO4).

[0130] The positive electrode active material layer may further include an adhesive and a conductive material. Depending on the requirements, the positive electrode active material layer may further include a thickener. In some embodiments, the adhesive may be polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylonitrile, polymethyl methacrylate, butadiene rubber, etc. In one embodiment, the positive electrode adhesive may be a PVdF-based adhesive.

[0131] The conductive material can be added to enhance the conductivity of the positive electrode active material layer and / or the mobility of lithium ions or electrons. For example, the conductive material may include carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes (CNTs), vapor-grown carbon fiber (VGCF), and carbon fibers, and / or metal-based conductive materials including perovskite materials such as tin, tin oxide, titanium oxide, LaSrCoO3, and LaSrMnO3, but is not limited thereto.

[0132] As needed, the positive electrode active material layer may further contain known thickeners and / or dispersants, etc.

[0133] In one embodiment, the negative electrode may include a negative electrode current collector and a layer of negative electrode active material formed on at least one side of the negative electrode current collector.

[0134] In exemplary embodiments, non-limiting examples of the negative electrode current collector include copper foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper, and polymer substrates coated with conductive metals. The thickness of the negative electrode current collector can be, for example, from 10 μm to 50 μm, but is not necessarily limited to this.

[0135] In one embodiment, the negative electrode active material layer may contain a negative electrode active material.

[0136] In an exemplary embodiment, the negative electrode active material can be a substance capable of adsorbing and desorbing lithium ions. For example, the negative electrode active material can be carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers; lithium metal; lithium alloys; silicon (Si)-containing materials; or tin (Sn)-containing materials.

[0137] Examples of the amorphous carbon may include hard carbon, soft carbon, coke, mesocarbon microbead (MCMB), mesophase pitch-based carbon fiber (MPCF), etc.

[0138] Examples of the crystalline carbon may include graphite-based carbons such as natural graphite, artificial graphite, graphitized coke, graphitized MCMB, graphitized MPCF, etc.

[0139] The lithium metal may include pure lithium metal or a lithium metal formed with a protective layer for inhibiting dendrite growth and the like.

[0140] Examples of the elements included in the lithium alloy may include aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium, or indium, etc.

[0141] The silicon-containing substance may provide further enhanced capacity characteristics. The silicon-containing substance may include Si, SiO x (0 < x < 2), metal-doped SiO x (0 < x < 2), silicon-carbon composites, etc. The metal may include lithium and / or magnesium, and metal-doped SiO x (0 < x < 2) may include metal silicate.

[0142] Non-limiting examples of the solvent for the negative electrode active material may include water, pure water, deionized water, distilled water, ethanol, isopropanol, methanol, acetone, n-propanol, tert-butanol, etc.

[0143] In one embodiment, the negative electrode active material layer may further contain a binder, and may optionally further contain additives such as a conductive material, a thickener, a dispersant, etc.

[0144] In an exemplary embodiment, the binder may be an adhesive that can be used without limitation and has an excellent binding force with the positive electrode current collector and / or the negative electrode current collector.

[0145] In some embodiments, the binder may be a rubber-based binder, a cellulose-based binder, a polyacrylic acid-based binder, a poly(3,4-ethylenedioxythiophene) (PEDOT)-based binder, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polymethyl methacrylate, etc.

[0146] The conductive material can be added to enhance the conductivity of the negative electrode active material layer and / or the mobility of lithium ions or electrons. For example, the conductive material may include: graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes including single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs), vapor-grown carbon fibers (VGCF), carbon fibers, and other carbon-based conductive materials; and / or metal-based conductive materials including perovskite minerals such as tin, tin oxide, titanium oxide, LaSrCoO3, and LaSrMnO3, but are not limited thereto.

[0147] In an exemplary embodiment, the thickener may be carboxymethylcellulose (CMC), methyl cellulose (MC), hydroxypropylcellulose (HPC), methyl hydroxypropyl cellulose (MHPC), ethyl hydroxyethyl cellulose (EHEC), methyl ethyl hydroxyethyl cellulose (MEHEC), and cellulose gum, etc.

[0148] In one embodiment, at least a portion of the first adhesive included in the coating of the diaphragm can simultaneously contact the substrate and the positive electrode, or simultaneously contact the substrate and the negative electrode.

[0149] In one embodiment, at least a portion of the first adhesive included in the coating of the diaphragm can simultaneously contact the substrate and the positive electrode.

[0150] In one embodiment, at least a portion of the first adhesive included in the coating of the diaphragm can simultaneously contact the substrate and the negative electrode.

[0151] In one embodiment, the entire first adhesive contained in the coating of the diaphragm can simultaneously contact the substrate and the positive electrode, or simultaneously contact the substrate and the negative electrode.

[0152] As described above, in an exemplary embodiment, when the diaphragm is viewed from the outside, at least a portion of the first adhesive may be configured to protrude from the surface of the coating, and in an embodiment described above, at least a portion of the first adhesive exposed to the outside may be in contact with the substrate on the other side.

[0153] Additionally, the diaphragm can be disposed between the positive and negative electrodes. Therefore, the exposed portion of the first adhesive (i.e., the portion protruding outwards from the coating) can contact either the positive or negative electrode.

[0154] With the embodiments described above, the first adhesive can simultaneously contact the positive electrode and the substrate, or simultaneously contact the negative electrode and the substrate, within the electrode assembly.

[0155] Furthermore, as described above, the first adhesive can be thermally bondable. Therefore, in one embodiment, the first adhesive can simultaneously bond to the positive electrode and the substrate, or simultaneously bond to the negative electrode and the substrate within the electrode assembly. That is, in the embodiment described above, each of the first adhesives can serve to bond the positive electrode and the substrate, or can serve to bond the negative electrode and the substrate.

[0156] By implementing the above-described embodiments, the adhesion or bonding force between the positive or negative electrode and the separator in the electrode assembly can be significantly improved. At the same time, effective adhesion or bonding force can be achieved even with a low content of the first adhesive. Therefore, problems that may occur when using the first adhesive can be effectively prevented, such as pore blockage caused by electrolyte swelling, increased battery resistance and deterioration of safety, or reduced processability and manufacturing economy.

[0157] In one embodiment, the electrode assembly can be manufactured by a method comprising the following steps: disposing a diaphragm according to one aspect of the invention between a positive electrode and a negative electrode; and applying heat and pressure to the unit body with the diaphragm disposed between the positive and negative electrodes to perform fusion.

[0158] The fusion step can be achieved by applying 10 kgf / cm along the lamination direction at a temperature of 80°C to 120°C. 2 Up to 30 kgf / cm 2 The pressure should be applied for 60 to 180 seconds, but it does not have to be limited to that.

[0159] In some implementations, the electrode assembly can be of the winding type, stacking type, z-folding type, or stack-folding type.

[0160] In an exemplary embodiment, when the electrode assembly is configured as a stack, it may include 2 to 60 positive electrodes and 2 to 60 negative electrodes along the stacking direction, and may be configured to provide the diaphragm between the positive electrodes and the negative electrodes along the stacking direction, but is not necessarily limited thereto.

[0161] According to one aspect of the invention, the electrode assembly can be included as a component of the secondary battery.

[0162] In one embodiment, the secondary battery may include: an electrode assembly according to one aspect of the invention; an outer casing material that houses the electrode assembly; and an electrolyte that is housed together with the electrode assembly within the outer casing material.

[0163] In one embodiment, the outer casing material may contain a receiving space and may be configured to isolate the object contained within the receiving space from the outside. The electrode assembly may be housed within and sealed in the receiving space of the outer casing material.

[0164] The outer packaging material can be appropriately selected as needed, such as pouch-type outer packaging material, can-type outer packaging material, coin-type outer packaging material, etc.

[0165] In one embodiment, the electrolyte may be housed together with the electrode assembly within the outer casing material. Specifically, the electrolyte may be housed together with the electrode assembly within a containment space of the outer casing material, and may be in contact with at least a portion of the electrode assembly within the containment space.

[0166] In one embodiment, the electrolyte can provide a pathway for ion migration.

[0167] According to an exemplary implementation, the electrolyte can be a non-aqueous electrolyte.

[0168] The non-aqueous electrolyte may contain lithium salt and an organic solvent, the lithium salt being, for example, derived from Li. + X - This indicates that the anion (X) of the lithium salt is... - ), can be exemplified by F - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 -(CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - (CF3SO2)2N - (FSO2)2N - CF3C(CF3)2COO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - wait.

[0169] The organic solvent may include an organic compound that has sufficient solubility for the lithium salt and additives and is non-reactive in the battery. The organic solvent may include at least one of, for example, carbonate-based solvents, ester-based solvents, ether-based solvents, ketone-based solvents, alcohol-based solvents, and aprotic solvents.

[0170] The non-aqueous electrolyte may further contain additives. These additives may include, for example, cyclic carbonate compounds, fluorinated carbonate compounds, sulcolone compounds, cyclic sulfate compounds, cyclic sulfite compounds, phosphate compounds, and borate compounds.

[0171] The secondary battery according to one aspect of the present invention can be preferably used not only as a battery cell for powering small devices, but also as a unit battery for battery modules and / or battery packs comprising multiple battery cells in medium and large-sized devices. Examples of such small devices include mobile phones, laptops, and cameras; examples of such medium and large-sized devices include electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and energy storage systems, but are not limited thereto.

[0172] The embodiments of the present invention will be further described below with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are only for illustrating the present invention and are not intended to limit the scope of the claims. Various changes and modifications can be made to the embodiments within the scope of the present invention and its technical concept, which is obvious to those skilled in the art, and such variations and modifications naturally fall within the scope of the claims.

[0173] Example 1. Example 1 (1) Manufacturing of the diaphragm Alumina particles (D50, 0.5 μm), acrylic latex (A-Latex), and polybutyl acrylate (PBA) (D50, 1.5 μm) with a glass transition temperature (Tg) of 50 °C were added to pure water and stirred to prepare a slurry. At this point, based on the total weight of the alumina particles and acrylic latex, the addition amount of acrylic latex was 5% by weight and the addition amount of PBA was 10% by weight.

[0174] Using a bar coater, the prepared slurry was coated onto both sides of a 7 μm thick polyolefin microporous membrane, and then dried to create a diaphragm with a coating on both sides of the microporous membrane. The coating thickness on each side was 1.0 μm.

[0175] (2) Manufacturing of the positive electrode Li[Ni] will be used as the positive electrode active material 0.88 Co 0.1 Mn 0.02 O2, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder are mixed and dispersed in N-methylpyrrolidone (NMP) solvent at a weight ratio of 96.5:2:1.5 to prepare a positive electrode slurry. The positive electrode slurry is then uniformly coated on an aluminum foil with a thickness of 12 μm and vacuum dried to form a positive electrode active material layer on the aluminum foil, thereby manufacturing a positive electrode.

[0176] (3) Manufacturing of the negative electrode Artificial graphite, single-walled carbon nanotubes (SWCNTs), styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC), which serve as negative electrode active materials, are mixed in a weight ratio of 98:0.5:0.3:1.2 and dispersed in distilled water to prepare a negative electrode slurry. The negative electrode slurry is then uniformly coated onto a copper foil with a thickness of 10 μm and vacuum dried to form a negative electrode active material layer on the copper foil, thereby manufacturing the negative electrode.

[0177] (4) Manufacturing of electrode components Prepare 45 positive electrodes and 46 negative electrodes manufactured as described above, and then stack them with the aforementioned separator placed between the positive and negative electrodes to assemble the core. Use a hot press to heat the assembled core at 100°C and 20.0 kgf / cm². 2 Electrode components are manufactured by thermal fusion under pressure for 120 seconds.

[0178] 2. Examples 2, 3, and Comparative Examples 1 to 4 The electrode assemblies of Examples 2, 3, and Comparative Examples 1 to 4 were manufactured using the same method as in Example 1, except that the coating thickness, type of inorganic material, particle size (D50) of the inorganic material, size (D50) of the first binder, content of the first binder, Tg of the first binder, type of the first binder, and content of the second binder were set as shown in Table 1 below. For comparison, the conditions of Example 1 are also shown in Table 1 below.

[0179] [Table 1] In Table 1, PBA stands for polybutyl acrylate, PEHA stands for ethylhexyl acrylate, and PAN stands for polyacrylonitrile.

[0180] Evaluation example The electrode assemblies of Examples 1 to 3 and Comparative Examples 1 to 4 were cooled to room temperature and then disassembled to evaluate the thermal fusion properties of the diaphragm and the electrode (positive or negative electrode).

[0181] The evaluation results confirm that in the electrode assemblies of Examples 1 to 3, proper thermal fusion was achieved between the diaphragm and the electrode, and the thickness after thermal fusion was also uniform.

[0182] On the other hand, in the electrode assemblies of Comparative Examples 1, 2 and 4, sufficient thermal fusion was not achieved between the diaphragm and the electrode, making it easy for the diaphragm and the electrode to separate. In the case of Comparative Example 3, although thermal fusion was achieved, the thickness was too large and the overall thickness was uneven, resulting in an overall uneven interface.

[0183] Based on the judgment, this is because, in the case of Comparative Example 1, the fusion between the diaphragm and the electrode was poor because the size of the first adhesive was too small relative to the coating thickness; in the case of Comparative Example 2, the fusion between the diaphragm and the electrode was poor because the content of the first adhesive was too small; and in the case of Comparative Example 4, even if thermal fusion was performed within the range where the electrode plate or diaphragm would not undergo thermal deformation, the fusion between the diaphragm and the electrode was poor because the glass transition temperature of the first adhesive was too high and thermal fusion could not be ensured.

[0184] On the other hand, in the case of Comparative Example 3, it can be confirmed that because the size of the first adhesive is too large relative to the coating thickness, although the fusion between the diaphragm and the electrode is ensured, the diaphragm and the electrode cannot adhere to each other to the level of contact, resulting in reduced adhesion, which in turn leads to poor structural stability.

[0185] In the case of Examples 1 to 3, which include a coating containing a first adhesive according to one aspect of the invention, it can be confirmed that the fusion between the diaphragm and the electrode is excellent, and at the same time, the interface is uniform, thus the adhesion is also excellent.

[0186] The above description is merely an example of applying the principles of the present invention, and may further include other configurations without departing from the scope of the present invention.

Claims

1. A diaphragm comprising: Substrate; as well as A coating, said coating being formed on at least one side of the substrate, The coating comprises an inorganic substance and a first binder. The glass transition temperature of the first adhesive is below 100°C. The diaphragm satisfies the following formula 1. [Formula 1] 1.2≤D B1 / T C ≤2.0 In Equation 1, D B1 D50 is the particle diameter when the cumulative particle size distribution of the first adhesive contains 50% by volume, and its unit is μm. C The thickness of the coating is expressed in μm.

2. The diaphragm according to claim 1, wherein, The diaphragm also satisfies the following formula 2. [Equation 2] 1.4≤D B1 / T C ≤1.8 In Equation 2, D B1 and T C The definition is the same as that in claim 1.

3. The diaphragm according to claim 1, wherein, At least a portion of the first adhesive is exposed to the outside while in contact with the substrate.

4. The diaphragm according to claim 1, wherein, The substrate comprises at least one of porous polymer and porous nonwoven fabric.

5. The diaphragm according to claim 1, wherein, The glass transition temperature of the first adhesive is 40°C to 60°C.

6. The diaphragm according to claim 1, wherein, The D B1 It is above 1.2μm.

7. The diaphragm according to claim 1, wherein, The first adhesive comprises: at least one selected from polyvinylidene fluoride (PVdF), polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), polybutyl acrylate (PBA), polyethylhexyl acrylate (PEHA), styrene-butadiene rubber (SBR), and polyethylene oxide (PEO); or copolymers of any two or more thereof.

8. The diaphragm according to claim 1, wherein, The T C The range is from 1 μm to 20 μm.

9. The diaphragm according to claim 1, wherein, The coating further comprises a second adhesive.

10. The diaphragm according to claim 9, wherein, The coating comprises the inorganic material and the second adhesive in a weight ratio of 60 to 99:40 to 1.

11. The diaphragm according to claim 9, wherein, The content of the first adhesive is from 1% to 30% by weight relative to the total weight of the inorganic material and the second adhesive.

12. A method for manufacturing a diaphragm according to any one of claims 1 to 11, comprising the following steps: Prepare the substrate; A diaphragm coating slurry is applied to at least one side of the substrate; as well as The coated diaphragm slurry is cured to form a coating on at least one side of the substrate. The diaphragm coating slurry comprises the inorganic material and the first adhesive.

13. The method for manufacturing a diaphragm according to claim 12, wherein, The diaphragm coating slurry further comprises a second adhesive.

14. The method for manufacturing a diaphragm according to claim 13, wherein, In the diaphragm coating slurry, the content of the first adhesive is from 1% to 30% by weight relative to the total weight of the inorganic material and the second adhesive.

15. An electrode assembly comprising: positive electrode; negative electrode; as well as The diaphragm according to any one of claims 1 to 11, wherein the diaphragm is disposed between the positive electrode and the negative electrode. In this process, at least a portion of the first adhesive is in contact with both the substrate and the positive electrode, or simultaneously with both the substrate and the negative electrode.

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