electrode

Abstract

The present application may provide an electrode, a manufacturing method for the electrode, and uses of the electrode. The present application may provide an electrode in which an insulating layer formed by overlapping an active material layer in a current collector layer of the electrode effectively ensures the insulation required of the electrode and does not form the fat edge portion. The present application may also provide a manufacturing method for manufacturing the above-mentioned electrode by flexibly dealing with changes in an electrode design model. The present application may also provide uses of the electrode.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2021-0092788 filed on 15 July 2021 and Korean Patent Application No. 10-2022-0087346 filed on 15 July 2022, and all content disclosed in the documents of the said patent applications is included herein as part of this specification.

[0002] This application relates to an electrode, a method for manufacturing the electrode, and an application for the electrode. [Background technology]

[0003] As technological development and demand for mobile devices and electric vehicles increase, the demand for secondary batteries as an energy source is also increasing.

[0004] Accordingly, much research is underway to meet the aforementioned demand.

[0005] A secondary battery generally includes an electrode assembly in which the positive and negative electrodes are stacked with a separator (separation membrane) in between, and an electrolyte, and the electrode assembly and electrolyte are housed in an outer casing.

[0006] Rechargeable batteries can be classified into can-type, rectangular-type, and pouch-type based on the shape of their outer casing.

[0007] One of the main research challenges in secondary batteries is improving safety. Accidents related to the safety of secondary batteries are caused by a variety of factors, but a typical factor is the short-circuit phenomenon that occurs between the positive and negative electrodes.

[0008] Under normal conditions, the separator provides electrical insulation between the positive and negative electrodes. However, in abnormal situations such as overcharging or over-discharging of the secondary battery, dendritic growth of the electrode material, internal short circuits due to foreign objects, or sharp objects such as nails penetrating the battery, the electrical insulation provided by the separator is damaged, leading to stability problems.

[0009] For example, if a secondary battery is exposed to high temperatures, a short circuit may occur due to the contraction of the separator, etc. Also, in general, multiple positive and negative electrodes are stacked together in the manufacture of a secondary battery, but during this stacking process, minute internal short circuits may occur due to the sharp edges of the positive and negative electrodes.

[0010] Considering these points, various attempts exist to ensure safety by preventing short circuits between the positive and negative electrodes due to internal or external problems in secondary batteries.

[0011] For example, Patent Document 1 discloses a method for ensuring insulation using an electrode in which an insulating layer is formed so as to partially overlap with the active material layer on the current collector layer.

[0012] However, as disclosed in Patent Document 1, when an active material layer and an insulating layer are superimposed in a certain area, the thickness of the superimposed area often becomes thicker than the thickness of the active material layer, and in such cases, the superimposed area is also called a so-called fat edge.

[0013] The presence of such fat edges can cause damage to the current collector layer during the rolling process in the electrode manufacturing process, potentially leading to safety issues. Furthermore, as mentioned above, the fat edge portion can damage other electrodes or separators during the process of stacking multiple positive and negative electrodes, or when stacking positive and negative electrodes with a separator in between.

[0014] To solve these problems, one can consider a method of forming the insulating layer as thin as possible. However, in such cases, the insulating effect of the insulating layer is greatly reduced. Also, when the insulating layer is formed thinly, the current collector layer may be exposed at the overlapping area between the insulating layer and the active material layer. Furthermore, if the difference in thickness between the insulating layer and the active material layer becomes excessively large, the efficiency of the rolling process may also decrease.

[0015] Therefore, the insulating layer of the electrode needs to be constructed to have an appropriate thickness to ensure insulation while avoiding the formation of the aforementioned fat edge portion.

[0016] The end of the active material layer formed on the current collector layer usually has an inclined surface called a sliding surface, and the insulating layer often overlaps with this inclined surface. Therefore, the required thickness of the insulating layer can be affected by the overlapping region of the active material layer and the insulating layer. The thickness of the active material layer also changes depending on the loading amount of the active material layer composition (slurry), and consequently, the required thickness of the insulating layer also changes.

[0017] Because electrode design models are often modified as needed due to diverse demands, the loading amount of the active material layer composition also changes depending on the process. Therefore, ensuring an appropriate insulating layer thickness for each process is not an easy challenge. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] International Publication No. 2014 / 142458 [Overview of the project] [Problems that the invention aims to solve]

[0019] This application can provide electrodes, methods for manufacturing electrodes, and applications for electrodes. This application can provide electrodes in which the insulating layer formed in the current collector layer overlapping the active material layer effectively ensures the required insulation properties of the electrode, while avoiding the formation of the aforementioned fat edge portion. Furthermore, this application can also provide a manufacturing method that can flexibly handle changes in the electrode design model and produce the aforementioned electrodes.

[0020] Furthermore, this application can provide applications for the aforementioned electrodes. [Means for solving the problem]

[0021] In this application, the term "room temperature" refers to the natural temperature of a material that is neither heated nor cooled, and may mean, for example, any temperature within the range of 10°C to 30°C, or a temperature that is approximately 15°C or higher, approximately 18°C ​​or higher, approximately 20°C or higher, or approximately 23°C or higher and approximately 27°C or lower, or approximately 25°C. In cases where the measurement temperature affects the physical properties referred to in this application, unless otherwise specified, the physical properties are those measured at room temperature, and unless otherwise specified, the unit of temperature in this application is Celsius (°C).

[0022] In this application, the term "atmospheric pressure" refers to the natural pressure that is not pressurized or depressurized, and typically means a pressure of approximately 1 atmosphere (atm). Furthermore, in cases where the measurement pressure affects the physical properties mentioned in this application, unless otherwise specified, the relevant physical properties are those measured at atmospheric pressure.

[0023] In this application, "multiple measurements" may mean that a certain physical property or relationship was measured at least three, four, five, six, seven, eight, nine, or ten times in order to derive statistically meaningful data. Furthermore, multiple measurements may mean that measurements were performed while changing the object being measured (e.g., layer thickness and overlapping region length) in order to derive statistically meaningful data.

[0024] In this application, "statistically meaningful" means that when a trend line (or trend curve) is drawn from the measurement results (data), R 2 This may mean that the value is 0.9 or greater, 0.91 or greater, 0.92 or greater, 0.93 or greater, 0.94 or greater, 0.95 or greater, 0.96 or greater, 0.97 or greater, or 0.98 or greater. 2 The value (R squared value) is the coefficient of determination used in statistical analysis.

[0025] This application relates to an electrode. In this application, the electrode may be a so-called anode or a cathode.

[0026] The electrode of this application may include a current collector layer, an electrode active material layer (which can simply be called an active material layer), and an insulating layer.

[0027] The active material layer and / or insulating layer may be formed on only one surface of the current collector layer, or on both surfaces of the current collector layer.

[0028] As mentioned above, the current collector layer can be any current collector layer that is normally used for the positive or negative electrode, without any particular restrictions.

[0029] The positive electrode current collector layer is not particularly limited in type, size, and shape, as long as it is conductive without inducing chemical changes in application devices such as secondary batteries. Examples of materials that can be used for the positive electrode current collector layer include stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc. The adhesion of the positive electrode active material can be enhanced by forming fine irregularities on the surface of the positive electrode current collector layer, and various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics are possible. Furthermore, the positive electrode current collector layer can typically have a thickness in the range of 3 μm to 500 μm.

[0030] The negative electrode current collector layer is not particularly limited in type, size, or shape, as long as it is conductive without inducing chemical changes in the application device such as a secondary battery. Examples of materials that can be used as the negative electrode current collector layer include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. Furthermore, similar to the positive electrode current collector layer, fine irregularities can be formed on the surface to strengthen the bonding force of the negative electrode active material, and it can be used in a variety of forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics.

[0031] The negative electrode current collector layer can typically have a thickness in the range of 3 μm to 500 μm.

[0032] The active material layer may be formed from an active material layer composition. Therefore, the active material layer may contain components included in the composition.

[0033] The active material layer composition or the active material layer may contain an electrode active material. There are no particular restrictions on the specific type of electrode active material, and materials that typically form a positive or negative electrode can be used.

[0034] For example, when the active material layer is the positive electrode active material layer, the active material is not particularly limited, but for example, layered compounds such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; lithium iron oxides such as LiFe3O4; chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0 ≤ c1 ≤ 0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented as O2 (where M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01 ≤ c2 ≤ 0.3); chemical formula LiMn 2-c3 M c3O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01 ≦ c3 ≦ 0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); lithium nickel cobalt manganese (NCM) composite oxide, lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and LiMn2O4 in which part of Li in the chemical formula is substituted with an alkaline earth metal ion can be exemplified, but are not limited thereto.

[0035] When the active material layer is a negative electrode active material layer, for example, a compound capable of reversible intercalation and deintercalation of lithium can be used as the active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β (0 < β < 2), metal oxides such as SnO2, vanadium oxide, and lithium vanadium oxide that can be doped and undoped with lithium; or composites containing the metallic compound and the carbonaceous material such as Si-C composite or Sn-C composite, etc. can be mentioned, and one or a mixture of two or more of these can be used.

[0036] A metallic lithium thin film may be used as the negative electrode active material. As the carbon material, low-crystallinity carbon and high-crystallinity carbon can be used. Typical low-crystallinity carbons include soft carbon and hard carbon, while typical high-crystallinity carbons include amorphous, plate-like, flake-like, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0037] The active material may be included in the active material layer composition in an amount of approximately 80% to 99.5% by weight or 88% to 99% by weight relative to the total weight of the composition, but the content is not limited to the above.

[0038] The active material layer composition or the active material layer may further contain a binder. The binder plays a role in improving adhesion between the active materials and between the active material layer and the current collector layer. Examples of the active material binder are not particularly limited and include, for example, polyvinylidene fluoride (PVDF), polyvinyl alcohol, styrene butadiene rubber, polyethylene oxide, carboxyl methyl cellulose, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. One or more compounds may be selected and used from the group consisting of sucrose, pullulan, polymethyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyarylate, and low molecular weight compounds with a molecular weight of 10,000 g / mol or less.

[0039] Typically, materials such as polyvinylidene fluoride or styrene-butadiene rubber can be used.

[0040] If the binder for the active material contains polyvinylidene fluoride, the weight-average molecular weight of the polyvinylidene fluoride may be in the range of 400,000 g / mol to 1,500,000 g / mol or 600,000 g / mol to 1,200,000 g / mol, in terms of improving adhesion to the active material layer and ensuring the desired viscosity. Here, the weight-average molecular weight can be measured using gel permeation chromatography (GPC). Furthermore, the melting point of the polyvinylidene fluoride may be 150°C to 180°C or 165°C to 175°C in order to improve solubility. Here, the melting point can be measured using differential scanning calorimetry (DSC).

[0041] The binder for the active material may be included in an amount of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the active material, but is not limited thereto.

[0042] The active material layer composition or active material may further contain a conductive material. The conductive material is not particularly limited as long as it is conductive without inducing a chemical change in the battery, and examples of such materials include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Kechen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes (CNTs); metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0043] The conductive material may be included in amounts ranging from 0.1 to 20 parts by weight or 0.3 to 10 parts by weight relative to 100 parts by weight of the active material, but is not limited thereto.

[0044] The active material layer composition may additionally contain a dispersion solvent. Since the dispersion solvent is almost completely removed by drying during the electrode manufacturing process, it is either not present in the active material layer or present in small amounts. Conventional types of dispersion solvents can be used, such as isopropyl alcohol, N-methylpyrrolidone (NMP), and / or acetone.

[0045] In the electrode, the electrode active material layer and the insulating layer are formed side by side along a direction perpendicular to the normal direction of the surface of the current collector layer, and may form overlapping portions with each other.

[0046] In other words, the insulating layer may be formed overlapping with the active material layer in at least a portion of its area. By forming such an overlapping area, the exposure of the current collector layer can be minimized, preventing short-circuit phenomena that occur when the positive and negative electrodes come into contact, and improving the quality and stability of the electrodes and the battery containing them.

[0047] The insulating layer can be formed using an insulating layer composition.

[0048] Therefore, the insulating layer may contain components included in the composition.

[0049] For example, the insulating layer composition or insulating layer may contain a binder. The binder may be included in an amount of about 30% to 70% or about 40% to 60% by weight relative to the total weight of the insulating layer composition, but is not limited thereto.

[0050] The binder for the insulating layer may be, for example, a component that imparts adhesion between the insulating layer and the current collector layer and / or the active material layer. The binder for the insulating layer is not particularly limited, but examples include polyvinylidene fluoride, polyvinyl alcohol, styrene butadiene rubber, styrene butadiene latex, polyethylene oxide, carboxyl methyl cellulose, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. One or more compounds from the group consisting of sucrose, pullulan, polymethyl methacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyarylate, and low molecular weight compounds with a molecular weight of 10,000 g / mol or less may be used. For example, as a binder applied to the insulating layer, styrene-butadiene rubber and / or styrene-butadiene latex can be used in terms of adhesion, chemical resistance, electrochemical stability, and efficiency in forming an insulating layer with the thickness relationship described later.

[0051] If the binder for the insulating layer contains styrene butadiene rubber and / or styrene butadiene latex, the glass transition temperatures of these materials, as measured by differential scanning calorimetry, may be -40°C or higher, -37.5°C or higher, -35°C or higher, -32.5°C or higher, or -30°C or higher, in terms of improving adhesion to the active material layer and ensuring the desired viscosity. In other examples, the glass transition temperatures may be -5°C or lower, -7.5°C or lower, or -10°C or lower. The glass transition temperatures can be measured using a differential scanning calorimetry (DSC).

[0052] The same compound as the binder for the active material layer may be used as the binder for the insulating layer. In this case, the bonding strength in the superposition region of the active material layer and the insulating layer may be further improved, thereby improving the stability, adhesion, and processability of the product.

[0053] As an example, the insulating layer composition or insulating layer may additionally contain a coloring agent. The coloring agent contained in the insulating layer may be one or more selected from the group consisting of disperse dyes, pigments, and organic phosphors. The coloring agent may be included in the insulating layer to confirm the formation or alignment position of the insulating layer through a detection device.

[0054] The coloring agent may be included in an amount of 0.1 to 10 parts by weight or 0.5 to 5 parts by weight relative to 100 parts by weight of the binder for the insulating layer, but is not limited thereto.

[0055] The aforementioned disperse dyes are not particularly limited and known dyes can be used. Examples of disperse dyes include benzene azos (monoazo, disazo), heterocyclic azos (thiazole azo, benzothiazole azo, pyridone azo, pyrazolone azo, thiophene azo, etc.), anthraquinones, and condensation dyes (quinophthalone, styryl, coumarin, etc.).

[0056] As one example, the disperse dyes applicable to this application may be as follows:

[0057] CIDisperse Yellow 3,4,5,7,9,13,24,30,33,34,42,44,49,50,51,54,56,58,60,63,64,66,68, 71,74,76,79,82,83,85,86,88,90,91,93,98,99,100,104,114,116,118,119 Yellow dyes such as 122, 124, 126, 135, 140, 141, 149, 160, 162, 163, 164, 165, 179, 180, 182, 183, 186, 192, 198, 199, 202, 204, 210, 211, 215, 216, 218, 224; CIDisperse Orange dyes such as 1, 3, 5, 7, 11, 13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 47, 48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89, 90, 91, 93, 96, 97, 119, 127, 130, 139, 142, etc.; CIDisperse Red 1,4,5,7,11,12,13,15,17,27,43,44,50,52,53,54,55,56,58,59,60,65,72,73,74,75,76,78,81,82,86,88,90,91,92,93,96,103,105,106,107,108,110,111,113,117,118,121,122,126,127,128,131,132,134,135,137,143,145,146,151,152,153, Red dyes such as 154, 157, 159, 164, 167, 169, 177, 179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203, 205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277, 278, 279, 281, 288, 289, 298, 302, 303, 310, 311, 312, 320, 324, 328; CIDisperse Violet dyes such as 1, 4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52, 56, 57, 59, 61, 63, 69, 77; CIDisperse Green 6:1,9 etc. (green dyes); CIDisperse Brown 1,2,4,9,13,19 etc. (brown dyes); CIDisperse Blue 3,7,9,14,16,19,20,26,27,35,43,44,54,55,56,58,60,62,64,71,72,73,75,79,81,82,83,87,91,93,94,95,96,102,106,108,112,113,115,118,120,122,125,128,130,139,141,142,143,146,148,149,153,15 Blue dyes such as 4, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186, 187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259, 267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330, 333, etc.; black dyes such as CIDisperse Black 1, 3, 10, 24, etc. can be used.

[0058] The aforementioned pigments are not particularly limited and known pigments can be used. Examples of organic pigments include azo pigments such as soluble azo pigments, insoluble azo pigments, and condensed azo pigments; quinacridone pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, polycyclic pigments such as diketopyrrolopyrrole pigments, and phthalocyanine pigments. Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides, and examples of carbon black include furnace black, lamp black, acetylene black, and channel black.

[0059] Examples of pigments that can be used in this application are as follows:

[0060] CIPigment Red: Red pigments such as 7, 9, 14, 41, 48:1, 48:2, 48:3, 48:4, 81:1, 81:2, 81:3, 122, 123, 146, 149, 168, 177, 178, 179, 187, 200, 202, 208, 210, 215, 224, 254, 255, 264; CIPigment Yellow Yellow pigments such as 1, 3, 5, 6, 14, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 93, 97, 98, 104, 108, 110, 128, 138, 139, 147, 150, 151, 154, 155, 166, 167, 168, 170, 180, 188, 193, 194, 213; Orange pigments such as CIPigment Orange 36, 38, 43; Blue pigments such as CIPigment Blue 15, 15:2, 15:3, 15:4, 15:6, 16, 22, 60; Green pigments such as CIPigment Green 7, 36, 58; Purple pigments such as CIPigment Violet 19, 23, 32, 50; CIPigment Black Black pigments of grade 7 can be used. Among these, CIPigment Red 122, CIPigment Yellow 74, 128, 155, CIPigment Blue 15:3, 15:4, 15:6, CIPigment Green 7, 36, CIPigment Violet 19, and CIPigment Black 7 can be used.

[0061] The aforementioned organic phosphor may, for example, be an organic phosphor having a carboxyl group and / or a phosphate group.

[0062] As the oil-soluble dyes, benzimidazolon compounds, azo compounds, quinophthalone compounds, quinacridone compounds, phthalocyanine compounds, DPP (Diketo-Pyrrolo-Pyrrole) compounds, and combinations of two or more of these can be used. Preferably, benzimidazolon compounds, azo compounds, and combinations of two or more of these can be used to improve recognition.

[0063] The colorant may further contain metal ions. Specifically, the colorant may include disperse dyes, pigments, and / or organic phosphors that form a complex salt structure with the metal ions. By having a complex salt structure with the metal ions, the disperse dyes, pigments, and / or organic phosphors can improve their solubility or dispersibility in solvents, and enhance their lightstability and heat resistance.

[0064] The aforementioned metal ions are not particularly limited as long as they can form a complex salt structure, and may include, for example, copper, cobalt, chromium, nickel and / or iron ions, preferably chromium ions.

[0065] The insulating layer composition or insulating layer may include a ceramic material (ceramic). For example, the ceramic may be included together with the binder. In such a case, the ceramic material may be included in an amount of 50 to 200 parts by weight, 75 to 150 parts by weight, 85 to 150 parts by weight, or 95 to 150 parts by weight relative to 100 parts by weight of the insulating layer binder.

[0066] By using the aforementioned ceramic material, the insulating layer can ensure excellent heat resistance. The aforementioned ceramic material may include, for example, one or more selected from the group consisting of metal oxides, metalloid oxides, metal fluorides, and metal hydroxides. Specifically, it may include one or more selected from the group consisting of AlO(OH), Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, and Mg(OH)2. The aforementioned ceramic material may be bohemite (AlO(OH)) as a suitable example.

[0067] The insulating layer composition or insulating layer may further contain a dispersant for ceramic materials to ensure the dispersibility of the ceramic material.

[0068] The ceramic material dispersant may be included in an amount of, for example, 0.01 to 5 parts by weight or 0.1 to 1 part by weight relative to 100 parts by weight of the ceramic material, but is not limited thereto.

[0069] For example, tannic acid can be used as the dispersant.

[0070] The insulating layer composition may additionally contain a dispersion solvent. Since this solvent can be removed during the electrode manufacturing process by drying or other means, it may not be present in the insulating layer of the final electrode, or may be present in small amounts.

[0071] The aforementioned dispersion solvent is not particularly limited as long as it is used in the industry, and for example, isopropyl alcohol, N-methylpyrrolidone (NMP), and / or acetone can be used.

[0072] The electrode of this application can be manufactured by the following method.

[0073] For example, the electrode can be manufactured by a method including the steps of applying the electrode active material layer composition onto the current collector and applying the insulating layer composition onto the current collector. In this case, there is no particular order in which the electrode active material layer composition and the insulating layer composition are applied, but typically the insulating layer composition is applied last.

[0074] The composition can be applied so as to form the electrode structure described above, and so the electrode active material layer and the insulating layer can be applied so as to form the electrode active material layer and the insulating layer side by side along a direction perpendicular to the normal direction of the surface of the current collector, and to form overlapping portions with each other.

[0075] Therefore, for example, in this application, the active material layer composition is first applied to the current collector layer 10, and the insulating layer composition can be applied so as to have an overlapping region with at least a portion of the active material layer composition.

[0076] When an active material layer composition is applied to a current collector layer, the end of the applied active material layer composition may be formed with an inclined surface known as a sliding portion. For example, an overlapping region may be created where the active material layer composition and the insulating layer composition come into contact, with the insulating layer composition applied to at least a portion of the inclined surface. The insulating layer 30 can then be formed by drying the applied composition so as to overlap at least a portion of the inclined surface of the active material layer (i.e., with the overlapping region still formed).

[0077] Figure 1 shows an example of an electrode including an electrode active material layer 20 and an insulating layer 30 formed on a current collector layer 10, wherein the electrode active material layer 20 and the insulating layer 30 overlap each other in region A. OL It forms this region A OL It can be confirmed that this is formed on the inclined surface of the electrode active material layer 20.

[0078] In such a structure, if the insulating layer 30 is thicker than the active material layer 20, damage may occur to the current collector layer 10 or separator during the rolling process or the manufacturing process of the electrode assembly. Furthermore, even if the insulating layer 30 is not thicker than the active material layer 20, the superimposed portion A OL If the surface of the insulating layer 30 is higher than the surface of the active material layer 20, the same problem as described above may occur.

[0079] Therefore, in the manufacturing method according to one example of this application, a process for determining the maximum average thickness of the insulating layer may be performed, and the coating thickness of the insulating layer composition may be controlled in the manufacturing process to be the same as or less than the maximum average thickness.

[0080] In this application, the maximum average thickness of the insulating layer means the maximum acceptable average thickness of the insulating layer in which no fat edge portion can be generated at the electrode.

[0081] Therefore, in the electrode manufacturing method described in this application, the coating thickness of the insulating layer composition can satisfy the following formula 4.

[0082] [Formula 4] T L ’ ≦T max

[0083] In equation 4, T max is the maximum average thickness of the insulating layer, T L ’ This is the coating thickness of the insulating layer composition.

[0084] By controlling the coating thickness of the insulating layer composition to satisfy this relationship, electrodes without the aforementioned fat edge portion can be effectively formed.

[0085] Due to diverse demands, the electrode design model is changed as needed, and the amount of active material composition loaded to form the active material layer 20 is not fixed. Consequently, it is necessary to predict the upper limit of the thickness of the insulating layer 30.

[0086] The electrode manufacturing method of this application, by considering the maximum average thickness of the insulating layer 30, can prevent short circuits, ensure stability, prevent damage to the battery, and flexibly accommodate changes in the electrode design model.

[0087] Accordingly, the electrode manufacturing method described in this application may include a step of determining the maximum average thickness of the insulating layer.

[0088] In this application, the term average thickness may mean the arithmetic mean of the thickness measured when any layer 100 is viewed from the side, at points that make up 20%, 30%, 40%, 50%, 60%, 70%, and 80% of the total transverse length, starting from one of the two ends of the layer. Referring to Figure 2, the layer 100 is shown as viewed from the side. Referring to Figure 2, if there is an arbitrary layer 100 with an overall horizontal length L of 500 mm, when the layer 100 is viewed from the side, one point P is selected from either end, and the thickness is measured at 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, and 400 mm from point P (D20%, D30%, D40%, D50%, D60%, D70%, and D80%), respectively, and the average value of these measurements can be called the average thickness. The thickness at each of these points can be measured using a thickness measuring instrument commonly used in this industry. Furthermore, unless otherwise specified, the term "thickness" in this application may mean the average thickness.

[0089] The meaning of the term "maximum average thickness" in this application is as described above.

[0090] In this application, the maximum average thickness of the insulating layer 30 can be determined by taking into consideration the average thickness of the electrode active material layer and / or the maximum overlapping area.

[0091] The average thickness of the electrode active material layer mentioned above may be either the actual thickness of the electrode active material layer in the electrode, or the thickness of the electrode active material layer intended by the electrode designer before manufacturing. In the latter case, the thickness of the electrode active material layer may be called the predetermined thickness of the electrode active material layer.

[0092] In this specification, the term "length of the superimposed region" refers to the total length of the superimposed region of the electrode active material layer and the insulating layer when viewed from the side. Figure 1 shows the superimposed region A of the electrode active material layer 20 and the insulating layer 30. OL The overall length when viewed from the side is denoted by L'.

[0093] Furthermore, the term "maximum length of the superimposed region" refers to the maximum acceptable length of the superimposed region where the fat edge portion cannot be generated at the electrode.

[0094] In this application, the average thickness of the electrode active material layer is not particularly limited, but it can typically be 50 μm or more, 52.5 μm or more, 55 μm or more, 57.5 μm or more, 60 μm or more, 62.5 μm or more, 65 μm or more, 67.5 μm or more, 70 μm or more, 72.5 μm or more, 75 μm or more, 77.5 μm or more, or 80 μm or more. Furthermore, there is no particular limit to the upper limit of the average thickness, but it can typically be 300 μm or less, 275 μm or less, 250 μm or less, 225 μm or less, or 200 μm or less. The average thickness of the electrode active material layer can be within the range formed by appropriately selecting the upper and lower limits mentioned above.

[0095] Furthermore, the length of the superimposed region or the maximum length of the superimposed region in the electrode of this application is not particularly limited, but is usually 0.001 mm or more, 0.005 mm or more, 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1 mm or more. The length of the superimposed region or the maximum length of the superimposed region may also be approximately 2 mm or less, 1.9 mm or less, 1.8 mm or less, 1.7 mm or less, 1.6 mm or less, 1.5 mm or less, 1.4 mm or less, 1.3 mm or less, or 1.2 mm or less, 1 mm or less, or 0.5 mm or less. The length of the superimposed region or the maximum length of the superimposed region may be within a range formed by appropriately selecting the upper and lower limits. Furthermore, if the length of the superimposed region or the maximum length of the superimposed region is within the range, it is possible to maximize the battery capacity while ensuring appropriate insulation and preventing short circuits between the positive and negative electrodes. The length of the superimposed region, i.e., the length of the superimposed region actually formed, may be the same as or smaller than the maximum length of the superimposed region.

[0096] Furthermore, the electrode manufacturing method according to one example of this application may be suitable when the average thickness of the predetermined active material layer and the maximum length of the predetermined superimposed region satisfy the above range.

[0097] In the electrode manufacturing method according to an example of this application, the step of determining the maximum average thickness of the insulating layer 30 is the average thickness T of the active material layer 20. a The thickness T of the active material layer 20 is determined by the distance from the insulating layer 30 to the active material layer 20 in the superimposed region. ax The ratio (T ax / T a The process may include a step of obtaining thickness profile data, which is data. The maximum average thickness of the insulating layer 30 is thickness profile data corresponding to the maximum length of the predetermined superimposed region, and the thickness T of the active material layer is determined by the distance from the insulating layer 30 to the electrode active material layer 20 in the superimposed region. ax This can be determined.

[0098] The thickness profile data has the horizontal axis as the distance from the insulating layer 30 to the active material layer 20, and the vertical axis as the ratio (T ax / T a When this is the case, it can be expressed in the form of an exponential function.

[0099] The aforementioned thickness profile data may be statistically meaningful data. Therefore, the R of the trend line (or trend curve) in the aforementioned function form in the aforementioned data 2 The values ​​are 0.9 or higher, 0.91 or higher, 0.92 or higher, 0.93 or higher, 0.94 or higher, 0.95 or higher, 0.96 or higher, 0.97 or higher, or 0.98 or higher.

[0100] Figure 6 is a diagram showing an enlarged view of the superposition region of the active material layer 20 and the insulating layer 30 in an example of an electrode manufactured by the electrode manufacturing method according to this application. In Figure 6, the direction from the insulating layer 30 to the active material layer 20 in the superposition region is indicated by X, and the point where the superposition region begins is X0 and the point where it ends is X n This is shown by X0 at X n The thickness of the active material layer 20 is the thickness corresponding to the aforementioned inclined surface, T ax As shown, the average thickness of the active material layer 20 is T a This is shown.

[0101] The average thickness T of the predetermined active material layer 20 a And in the superimposed region, the thickness T of the active material layer 20 is determined by the direction from the insulating layer 30 to the active material layer 20. ax The ratio (T ax / T a The step of obtaining the thickness profile data, which is the data, is as shown in Figure 6, with X0 at X n T by ax and T a The ratio (T ax / T a By measuring () and displaying the measurement results in a graph, the data can be obtained in functional form.

[0102] Referring to Figure 7, the direction from the insulating layer 30 to the active material layer 20 (i.e., from X0 to X in Figure 6)n (In the direction leading to) the aforementioned T ax and T a The ratio (T ax / T a You can measure ) and see an example graph showing the results.

[0103] In one example of this application, based on a graph like that shown in Figure 7, T ax / T a The value is derived, and the average thickness T of the predetermined active material layer is determined. a The derived T ax / T a T obtained by substituting the value ax The value is the maximum average thickness of the insulating layer 30 (T in Equation 4). max ) can be determined to be.

[0104] For example, referring to Figure 7, y is T ax / T a And x is X0 (=0mm) ~ X n When the distance is (=10mm), many data (X0~X n The point in between is the corresponding T ax / T a The trend curve formed through the data of values ​​is y = a₀ + a₁₀ × exp(a 7× A function of x)(a5, a6, and a7 are constants) can be obtained. To find the maximum average thickness, the equation (1-y), obtained by subtracting the result of the above equation from 1, can be used. For example, if the maximum length of the superimposed region is 1 mm, then the T in the above equation can be obtained. ax / T a The value is a5 + a6 × exp(a7 × 1 mm), but the result obtained by subtracting the above from 1 is (1 - a5 + a6 × exp(a7 × 1 mm)) and the average thickness T of the active material layer 20. a The value obtained by multiplying by the value obtained is the maximum average thickness of the insulating layer 30 (T in Equation 4). max ) can be determined to be.

[0105] Therefore, as an example, T in equation 4 above max This can be determined by the following equation 5.

[0106] [Formula 5] T max =T a ×{a×exp(b×L)-c}

[0107] In equation 5, T a L is the average thickness of the active material layer, and L is the maximum length of the superimposed region.

[0108] In equation 5, T a L is the average thickness of the active material layer, and L is the maximum length of the superimposed region.

[0109] In equation 5, T a The unit for is μm, and the unit for L is mm.

[0110] In Equation 5, a, b, and c are arbitrary constants. There are no particular restrictions on the ranges of a, b, and c.

[0111] As an example, a may be 0.55 or more, 0.6 or more, 0.7 or more, or 0.75 or more. Alternatively, a may be approximately 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, or 0.76 or less. The range of a may be a combination of one of the lower limits and one of the upper limits mentioned above.

[0112] As an example, b may be -0.8 or greater, -0.75 or greater, -0.7 or greater, -0.65 or greater, -0.6 or greater, -0.55 or greater, or -0.5 or greater. b may also be -0.2 or less, -0.25 or less, -0.3 or less, -0.35 or less, -0.4 or less, -0.45 or less, or -0.49 or less. The range of b may be a combination of any one of the lower limits and any one of the upper limits mentioned above.

[0113] As an example, c may be 0.001 or more, 0.0015 or more, or 0.002 or more. c may also be 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, or 0.0022 or less. The range of c may be a combination of any one of the lower limits and any one of the upper limits mentioned above.

[0114] Applying the ranges a, b, and c, the T of Equation 4 is obtained by Equation 5. max By determining this, electrodes that are suitable for the purpose of this application can be manufactured more efficiently.

[0115] In an example of the electrode manufacturing method according to this application, the step of determining the maximum average thickness of the insulating layer may include a step of obtaining loading data including thickness data of the active material layer based on the loading amount of the active material layer composition per unit area; and a step of obtaining maximum length data of the superimposed region based on the loading amount of the active material layer composition per unit area for specific thicknesses of the insulating layer.

[0116] The step of determining the maximum average thickness of the insulating layer may be performed by deriving a loading amount from the loading data such that the active material layer has a predetermined average thickness of the active material layer, and then applying the derived loading amount of the active material layer composition and the predetermined maximum length of the superimposed region to the data of the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area for a specific thickness of the insulating layer to derive the maximum average thickness of the insulating layer.

[0117] The step of obtaining loading data, which includes data on the thickness of the active material layer based on the loading amount of the active material layer composition per unit area, can be described by referring to the explanation of the step of applying the active material layer composition below. Based on the loading data, a loading amount can be derived that allows the active material layer to have a predetermined average thickness. For example, referring to Figure 3, the loading amount of the active material layer composition that matches the predetermined average thickness of the active material layer 20 can be calculated by working backward through the function described above.

[0118] The data represents the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area for each specific thickness of the insulating layer, where the specific thickness of the insulating layer refers to the desired thickness of the insulating layer formed after the insulating layer composition is applied.

[0119] Here, the data for the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area for specific thicknesses of the insulating layer may be statistically meaningful. Furthermore, the data for the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area for specific thicknesses of the insulating layer can be expressed in the form of a logarithmic function, with the horizontal axis representing the loading amount of the active material layer composition per unit area and the vertical axis representing the maximum length of the superimposed region.

[0120] In other words, the electrode manufacturing method according to one example of this application can determine the maximum average thickness of the insulating layer by considering an insulating layer having a specific thickness and a predetermined maximum length of the overlapping region, based on data of the maximum length of the overlapping region obtained by the loading amount of the active material layer composition per unit area for specific thicknesses of the insulating layer.

[0121] Here, the length of the superimposed region may refer to the lateral length of the region at the end of the active material layer 20 that overlaps with the insulating layer 30 at the inclined surface portion. Furthermore, the inclined surface portion refers to the end portion of the active material layer 20 that is smaller than the average thickness and is inclined. Referring to Figure 4, the average thickness T at the end portion of the active material layer 20. a Smaller and more inclined portion A SL It can be seen that there is a sloping surface portion A. SL The portion A that is inclined laterally includes the region that overlaps with the insulating layer 30. SL Ls, which is the length of the superimposed region, can be the maximum length of the superimposed region.

[0122] In other words, in this specification, the maximum length of the superimposed region is the average thickness T of the electrode active material layer at the end portion of the electrode active material layer 20. a Thinner part A SL It can mean length.

[0123] The insulating layer 30 is the inclined surface portion A of the active material layer 20. SL Although at least a portion of them overlap, the insulating layer 30 has an average thickness T of the active material layer 20. a Since it is the same size as or lower than the other area, the region where it can be most likely to overlap is ultimately the inclined surface portion A in Figure 4. SL And these are the horizontal lengths L S This could be the maximum length of the superimposed region.

[0124] Referring to Figure 5, an example of maximum length data of the superimposed region based on the loading amount of the active material layer composition per unit area for specific thicknesses of the insulating layer can be confirmed. The maximum length data of the superimposed region can be obtained as a function by measuring the length of the inclined surface portion at the end of the active material layer 20 based on the loading amount of the active material layer composition per unit area for each thickness of the insulating layer, and showing the measurement results in a graph.

[0125] Referring to Figure 5, y is the maximum length of the superimposed region, and x is the loading amount per unit area of ​​the active material layer composition (in this case, the unit area is 25 cm²). 2 When assuming that (i.e., if we want to obtain an insulating layer 30 having an average thickness of P1 μm, we can obtain a function y = a3 ln(x) + a4 (where a3 and a4 are constants) from a trend curve formed through a lot of data. Even when the average thickness of the insulating layer 30 is not P1 μm but P2 μm or P3 μm, etc. (and may be added further), (where P1, P2, and P3 are all different constants), we can obtain the same function as described above in the same manner.

[0126] From the numerous trend curves obtained from the aforementioned data, a trend curve is derived that passes through the point where a constant function corresponding to the loading amount of the active material layer composition derived from the data (i.e., x = function corresponding to the loading amount) and a constant function corresponding to the maximum length of the predetermined superimposed region (i.e., y = function corresponding to the maximum length of the predetermined superimposed region) touch each other. At this point, the average thickness of the insulating layer 30 in the trend curve can be determined to be the maximum average thickness of the insulating layer 30 according to an example of this application.

[0127] For example, referring to Figure 8, the resulting loading amount of the active material layer composition is approximately 200 mg / 25 cm 2 Therefore, if the maximum length of the predetermined superimposed region is approximately 0.5 mm, constant functions with x=200 and y=0.5 can be plotted in the data corresponding to Figure 5, and the point where these functions touch each other (see dotted circle) can be derived. Here, the trend curve passing through the point is for when the average thickness of the insulating layer is P3 μm, and P3 μm can be determined as the maximum average thickness of the insulating layer 30. Figure 8 shows an example of determining the maximum average thickness of the insulating layer, and the derived loading amount of the active material layer composition is approximately 200 mg / 25 cm 2 This example illustrates a case where the maximum length of the predetermined superimposed region is approximately 0.5 mm.

[0128] In an example of an electrode manufacturing method according to this application, the step of applying the active material layer composition may be carried out by additionally including a step of obtaining loading data including thickness data of the active material layer 20 based on the loading amount of the active material layer composition per unit area, and applying the active material layer composition in an amount that allows the active material layer 20 to have a predetermined average thickness of the active material layer 20 based on the loading data.

[0129] Here, the thickness data of the active material layer 20 based on the loading amount of the active material layer composition per unit area may be statistically meaningful. Furthermore, the thickness data of the active material layer 20 based on the loading amount of the active material layer composition per unit area can be expressed in the form of a linear function.

[0130] Referring to Figure 3, an example of the thickness data of the active material layer 20 based on the loading amount of the active material layer composition per unit area can be seen. The thickness data of the active material layer 20 can be obtained as a function by measuring the average thickness of the active material layer 20 formed by the loading amount of the active material layer composition per unit area and showing the measurement results in a graph. In Figure 3, y is the average thickness of the active material layer, and x is the loading amount of the active material layer composition per unit area (at this time, the unit area is 25 cm²). 2 Assuming that (this is the case), a function y = a1x + a2 (where a1 and a2 are constants) can be obtained from the trend line formed through a large amount of data, and the loading amount of the active material layer composition that matches the predetermined average thickness of the active material layer 20 can be calculated by inversely determining it through this function.

[0131] In other words, the electrode manufacturing method according to one example of this application allows for the determination of the loading amount of the active material layer composition in order to achieve a predetermined average thickness of the active material layer 20 based on the thickness data of the active material layer 20 determined by the loading amount of the active material layer composition per unit area.

[0132] The electrode manufacturing method described in this application, as an example, can easily accommodate changes in the electrode design model and / or the required thickness of the active material layer and / or the length of the superimposed region through the aforementioned method.

[0133] In the electrode manufacturing method described in this application, the method for applying the active material layer composition and the insulating layer composition onto the current collector layer 10 is not particularly limited as long as it is a method commonly used in the industry, and one of slot die coating, slide coating, and curtain coating can be used independently for each.

[0134] An example of an electrode manufacturing method according to this application may include the step of drying the active material layer composition and the insulating layer composition applied on the current collector layer 10 to form the active material layer 20 and the insulating layer 30. The drying method is not particularly limited as long as it is a commonly used method in the industry, and one of the following methods can be used: hot air method, infrared irradiation method, and induction heating method. The drying temperature is not particularly limited as long as the active material layer composition and the insulating layer composition can be sufficiently dried, but it may be between 50°C and 200°C, and the drying time may be between 1 and 10 minutes.

[0135] An example of an electrode manufacturing method according to this application allows for the manufacture of electrodes by performing a rolling process after drying. The rolling process increases the active material capacitance density, thereby increasing the adhesion between the current collector layer 10 and the active material layer 20, between the current collector layer 10 and the insulating layer 30, and between the active material layer 20 and the insulating layer 30. Furthermore, the rolling method used in the rolling process is not particularly limited as long as it is a commonly used method in the industry, and may be a process in which the entire current collector layer 10 on which the dried active material layer 20 and insulating layer 30 are formed is compressed with a rolling member, and the rolling member can be a rolling roller or a rolling jig.

[0136] This application also relates to electrodes.

[0137] The electrode of this application may be manufactured by the manufacturing method described above, as one example.

[0138] As an example, the electrode may include a current collector layer; an electrode active material layer formed on the current collector layer; and an insulating layer formed on the current collector layer.

[0139] As described above, in the electrode, the electrode active material layer and the insulating layer are formed side by side along a direction perpendicular to the normal direction of the surface of the current collector layer, and may also form overlapping portions of each other.

[0140] The insulating layer can satisfy the relationship shown in Equation 1 below.

[0141] [Formula 1] T L ≤ T S × {a × exp(b × L) - c}

[0142] In Equation 1, T L is the thickness of the insulating layer, T S is the thickness of the active material layer, and L is the length of the overlapping part.

[0143] In Equation 1, T L and T S are in μm, and the unit of L is mm.

[0144] The thickness of the insulating layer can be the aforementioned average thickness, and the thickness of the active material layer can also be the average thickness of the active material layer.

[0145] Also, the L can be the actual length of the overlapping part (e.g., L' in FIG. 1), or the maximum length of the aforementioned overlapping region, that is, the maximum allowable length of the overlapping region where the fat edge part cannot occur at the electrode. As described above, the maximum length of the overlapping region is the length of the portion A a thinner than the average thickness T SL of the electrode active material layer at the end portion of the electrode active material layer 20 (Ls in FIG. 4).

[0146] The relationship of Equation 1 is the thickness relationship shown by the insulating layer formed by controlling the coating thickness of the insulating layer composition according to the content of Equation 5 described above, and this has been experimentally confirmed.

[0147] In Equation 1, a, b, and c are arbitrary constants. The respective ranges of a, b, and c are not particularly limited.

[0148] As an example, a can be 0.55 or more, 0.6 or more, 0.7 or more, or 0.75 or more. Also, a may be about 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, or 0.76 or less. The range of a can be within the range combined by any one of the aforementioned lower limits and any one of the aforementioned upper limits.

[0149] In one example, b can be -0.8 or more, -0.75 or more, -0.7 or more, -0.65 or more, -0.6 or more, -0.55 or more, or -0.5 or more. b may be -0.2 or less, -0.25 or less, -0.3 or less, -0.35 or less, -0.4 or less, -0.45 or less, or -0.49 or less. The range of b can be within the range combined by any one of the aforementioned lower limits and any one of the aforementioned upper limits.

[0150] In one example, c can be 0.001 or more, 0.0015 or more, or 0.002 or more. c may be 0.004 or less, 0.0035 or less, 0.003 or less, 0.0025 or less, or 0.0022 or less. The range of c can be within the range combined by any one of the aforementioned lower limits and any one of the aforementioned upper limits.

[0151] By satisfying the relationship of Formula 1, it is possible to form an insulating layer or an electrode in which the fat edge portion does not exist and excellent insulation is ensured.

[0152] The electrode can additionally satisfy the following Formula 2.

[0153] [Formula 2] 0.1×T S ≦T L

[0154] In Formula 2, T L and T S are respectively the same as T L and T S in Formula 1. L およびT S と同一である。

[0155] In Formula 2, T L は、他の例示で0.15×T S 以上または0.2×T S 以上であってもよい。

[0156] By satisfying the relationship in Equation 2, the insulating properties of the insulating layer are stably ensured, the phenomenon of excessively large deviations in the thickness of the insulating layer and the active material layer is prevented, and the phenomenon of the current collector layer being exposed at the boundary between the insulating layer and the active material layer can be effectively prevented.

[0157] On the other hand, the electrode can additionally satisfy the following equation 3.

[0158] [Formula 3] T S =d × L D +e

[0159] In equation 3, T S is T in Equation 1 S It is identical to L D This is the loading amount of the active material layer (unit: mg / 25cm³). 2 ) where d is a number in the range of 0.1 to 0.2, and e is a number in the range of 10 to 16.

[0160] Equation 3 is the relationship between the loading amount of the active material layer (or active material layer composition) and the thickness of the active material layer, which was experimentally derived from the relation shown in Figure 3.

[0161] In Equation 3, d may be 0.12 or greater, 0.14 or greater, or approximately 0.18 or less, or 0.16 or less, as in other examples.

[0162] In equation 3, e may be 11 or greater, 12 or greater, or approximately 15 or less, 14 or less, or 13 or less, as in other examples.

[0163] As mentioned above, the average thickness of the electrode active material layer is not particularly limited by formulas 1 to 3, but it can usually be 50 μm or more, 52.5 μm or more, 55 μm or more, 57.5 μm or more, 60 μm or more, 62.5 μm or more, 65 μm or more, 67.5 μm or more, 70 μm or more, 72.5 μm or more, 75 μm or more, 77.5 μm or more, or 80 μm or more. Furthermore, there is no particular limit to the upper limit of the average thickness, but the average thickness can usually be 300 μm or less, 275 μm or less, 250 μm or less, 225 μm or less, or 200 μm or less. The average thickness of the electrode active material layer can be within the range formed by appropriately selecting the upper and lower limits mentioned above.

[0164] The length L of the overlapping portion in formula 1 can be 0.001 mm or more, 0.005 mm or more, 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1 mm or more, and can be approximately 2 mm or less, 1.9 mm or less, 1.8 mm or less, 1.7 mm or less, 1.6 mm or less, 1.5 mm or less, 1.4 mm or less, 1.3 mm or less, or 1.2 mm or less, 1 mm or less, or 0.5 mm or less. The length range can be within the range formed by appropriately selecting the upper and lower limits.

[0165] The length L mentioned above may be the actual length of the superimposed region at the electrode, or it may be the maximum length of the superimposed region as described above.

[0166] By setting the length above the lower limit, it is possible to prevent the current collector layer from being exposed at the overlapping portion of the insulating layer and the active material layer, and to prevent the efficiency in the rolling process from decreasing due to an excessively large difference in the thickness of the insulating layer and the active material layer, thereby ensuring appropriate insulation. Furthermore, by setting the length below the upper limit, it is possible to maximize the battery capacity while effectively preventing the occurrence of fat edge portions.

[0167] The specific materials for the current collector layer, insulating layer, and active material layer are as described in the respective sections on manufacturing methods.

[0168] This application can also provide an electrode assembly or a secondary battery including the said electrode.

[0169] As is well known, an electrode assembly includes a negative electrode; a positive electrode; and a separator, and has a structure in which the negative electrode and the positive electrode are stacked with the separator in between, but the electrode of this application can be used as either the negative electrode or the positive electrode.

[0170] The secondary battery may be a lithium-ion battery. The secondary battery also includes a positive electrode, a negative electrode positioned opposite the positive electrode, a separator interposed between the positive and negative electrodes, and an electrolyte. In this case, the secondary battery may optionally further include a battery container housing the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0171] The separator separates the negative and positive electrodes and provides a passage for lithium ions to move. Any separator commonly used in this industry can be used without particular restrictions, and it is especially preferable that it has low resistance to the movement of electrolyte ions while having excellent electrolyte moisture retention capacity. Specifically, porous polymer films, such as porous polymer films made from polyolefin polymers such as ethylene polymer, propylene polymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof can be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, coated separators containing ceramic components or polymeric substances to ensure heat resistance or mechanical strength may be used, and they can be selectively used in single-layer or multi-layer structures.

[0172] The electrolyte can be, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, gel-type polymer electrolytes, or molten inorganic electrolytes commonly used in this industry. Specifically, the electrolyte may contain organic solvents and lithium salts.

[0173] The aforementioned organic solvent can be any solvent that can act as a medium through which ions involved in the electrochemical reaction of the battery can move, without any particular limitations. Specifically, the aforementioned organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group with 2 to 20 carbon atoms, and can include a double-bond oriented ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred. In this case, mixing the cyclic carbonate and the linear carbonate in a volume ratio of about 1:1 to about 1:9 can show excellent electrolyte performance.

[0174] The lithium salt can be any compound capable of providing lithium ions for use in lithium secondary batteries, without any particular limitations. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably within the range of 0.1 to 2.0 M. When the concentration of the lithium salt falls within this range, the electrolyte has appropriate conductivity and viscosity, exhibiting excellent electrolyte performance and allowing lithium ions to move effectively.

[0175] In addition to the electrolyte components, the electrolyte may further contain one or more additives for the purpose of improving battery life characteristics, suppressing the decrease in battery capacity, and improving battery discharge capacity, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphate, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidinone, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be present in an amount of 0.1 to 5% by weight relative to the total weight of the electrolyte.

[0176] Furthermore, the aforementioned secondary battery can be applied to portable devices such as mobile phones, laptop computers, and digital cameras, as well as to electric vehicles such as hybrid electric vehicles (HEVs). [Effects of the Invention]

[0177] This application can provide electrodes, methods for manufacturing electrodes, and applications for electrodes. This application can provide electrodes in which the insulating layer formed in the current collector layer overlapping the active material layer effectively ensures the required insulation properties of the electrode, while avoiding the formation of the aforementioned fat edge portion. Furthermore, this application can also provide a manufacturing method that can flexibly handle changes in the electrode design model and produce the aforementioned electrodes.

[0178] Furthermore, this application can provide applications for the aforementioned electrodes. [Brief explanation of the drawing]

[0179] [Figure 1] This is a side view of an electrode according to an example of this application. [Figure 2] This is a schematic diagram illustrating the average thickness used in this application. [Figure 3] This is an example of thickness data based on the loading amount of the active material layer composition. [Figure 4] This is a diagram illustrating the maximum length of the superimposed region. [Figure 5] This is an example of data showing the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area for different insulating layer thicknesses. [Figure 6] This is a side view of an electrode according to an example of this application. [Figure 7] This is an example of the results obtained by measuring the ratio of Tax to Ta (Tax / Ta) based on the distance from the insulating layer to the active material layer. [Figure 8] This graph shows an example of how to determine the maximum average thickness of the insulating layer. [Figure 9] This is a Scanning Electron Microscope (SEM) image of the electrode in Example 1. [Figure 10] This is a Scanning Electron Microscope (SEM) image of the electrode in Comparative Example 1. [Modes for carrying out the invention]

[0180] The contents of this application will be described in detail below through examples and comparative examples, but the scope of this application is not limited to what is presented below.

[0181] Production example 1. Composition for electrode active material layer Lithium nickel cobalt manganese aluminum (NCMA) composite oxide (NCMA), binder (PVDF, Poly(vinylidene fluoride)) (KF9700, Kureha Corporation, weight-average molecular weight (Mw): 8.8 × 10⁻⁶) 5 A composition (slurry) for the positive electrode active material layer was prepared by mixing (g / mol) and conductive material (carbon nanotubes, CNTs) in a weight ratio of 97:1.5:1.5 (NCMA:PVDF:CNT) and dispersing them in N-methylpyrrolidone (NMP) so that the solid content was approximately 70% by weight.

[0182] Manufacturing Example 2. Composition for Insulating Layer A composition for an insulating layer was prepared by mixing SBR (styrene butadiene rubber) (BM-L302, ZEON) as a binder (B1), bohemite (AlO(OH), product name: AOH60) as a ceramic material (B2), tannic acid as a dispersant (B3), and Yellow 081 (manufacturer: BASF) as an organic dye (B4) in a weight ratio of 50:49:0.1:0.9 (B1:B2:B3:B4), and adding it to N-methylpyrrolidone (NMP) to achieve a solid content of approximately 15% by weight.

[0183] Test Example 1. Active Material Layer Thickness Data Based on Loading Amount Area is 25cm 2 The positive electrode active material layer composition was applied to one surface of the aluminum current collector layer in a loading amount ranging from approximately 100 mg to 700 mg, and then dried with hot air at approximately 130°C for about 1 minute to form an active material layer. The average thickness of the active material layer (excluding the current collector layer thickness) was then measured.

[0184] The above procedure was repeated to create a graph showing the relationship between the loading amount of the positive electrode active material layer composition and the average thickness of the active material layer. This graph is shown in Figure 3. The relationship is illustrated by the linear function graph y = a1x + a2 in Figure 3 (a function represented by a trend line). 2 When the value was 0.98 or higher, a1 was approximately 0.1516 and a2 was approximately 12.62.

[0185] Test Example 2. Maximum Length Data of the Overlapping Region Area is 25cm 2 The positive electrode active material layer composition was applied to the aluminum current collector layer in a loading amount ranging from approximately 100 mg to 700 mg, and then the insulating layer composition was applied again so that the active material layer 20 and the insulating layer 30 were formed on the current collector layer 10 as shown in Figure 1. Subsequently, the active material layer and insulating layer (average thickness: P1 μm) were formed by drying with hot air at approximately 130°C for about 1 minute.

[0186] Under the aforementioned conditions, the length of the inclined surface portion formed at the end of the active material layer (Ls in Figure 4) (maximum length of the superimposed region) was measured. The above process was repeated while changing the loading amount of the positive electrode active material layer composition within the range of approximately 100 mg to 700 mg, and when the average thickness of the insulating layer was P1 μm, data for the maximum length of the superimposed region based on the loading amount of the active material layer composition per unit area was obtained. This result is shown in Figure 5. The results in Figure 5 are obtained using the same method, but with the average thickness of the insulating layer set to different values ​​of P1 μm, P2 μm, and P3 μm (P1, P2, and P3 are different constants). For each average thickness of the insulating layer, the data is shown in the form of a logarithmic function y = a3 ln(x) + a4 (a3 and a4 are constants) (a function based on a trend curve). Specifically, when the average thickness P1 of the insulating layer is 15, a3 is approximately +1.5686 and a4 is approximately -6.786; when P2 is 20, a3 is approximately +1.5725 and a4 is approximately -7.379; and when P3 is 25, a3 is approximately +1.5748 and a4 is approximately -7.836. R in all the above data 2The value is 0.98 or higher. The data in Figure 5 is representative of the cases where the thickness of the insulating layer is set to P1 μm, P2 μm, and P3 μm. The maximum length data of the superimposed region based on the loading amount of the active material layer composition per unit area for each specific thickness of the insulating layer can be obtained identically even when the thickness of the insulating layer is different from P1 μm, P2 μm, and P3 μm, in order to determine the maximum average thickness of the insulating layer.

[0187] Test Example 3. Average thickness T of the active material layer a The thickness T of the active material layer is determined by the distance along the direction from the insulating layer to the active material layer in the superimposed region. ax The ratio (T ax / T a )data Area is 25cm 2 The positive electrode active material layer composition was applied to the aluminum current collector layer and dried with hot air at approximately 130°C for 1 minute to form the active material layer.

[0188] At one of the two ends of the active material layer, the point where the height is 0 (the starting point of the active material layer) is designated as the origin (X0), and the thickness T of the active material layer is measured in the direction toward the center of the active material layer based on the distance from the origin. ax The average thickness T of the active material layer a Ratio to (T ax / T a ) was measured.

[0189] The above measurements were repeated while changing the loading amount of the composition for the positive electrode active material layer, and the results were plotted as a graph (a function based on a trend curve).

[0190] The relevant results are shown in Figure 7, and the graph is illustrated in the form of an exponential function y = a5 + a6 × exp(a7 × x) (where a5, a6, and a7 are constants). In the above, a5 is approximately +1.00219, a6 is approximately -0.7514, and a7 is approximately -0.49972, and R 2 The value was 0.98 or higher.

[0191] Taking these results into consideration, equation 5 can be derived as shown in equation A below.

[0192] [Formula A] T max =T a ×{a×exp(b×L)-c}

[0193] In equation A, T a is the average thickness of the active material layer, L is the maximum length of the superimposed region, a is approximately 0.7514, b is approximately -0.4992, and c is approximately 0.00219.

[0194] Example 1. Determination of the maximum average thickness of the insulating layer An electrode was designed with an average active material layer thickness of approximately 93 μm and a maximum superimposed region length of 0.5 mm. According to the results of Test Example 1, the unit area required to ensure the aforementioned average thickness of 93 μm is 25 cm². 2 The loading amount of the active material layer composition per unit is approximately 530 mg.

[0195] Substitute 0.5 mm for L into equation A, which is the result obtained in test example 3, and T a Substituting 93 μm into the calculation, the maximum average thickness of the insulating layer (T max The size of the spur is confirmed to be approximately 54.2 μm.

[0196] Electrode manufacturing The electrodes were manufactured according to the design described above. As previously stated, when considering the results of Test Example 1 and Figure 3, the loading amount of the active material layer composition to ensure a thickness of 93 μm was approximately 530 mg / 25 cm². 2 It is to that extent.

[0197] The active material layer composition was applied to an aluminum foil (foil) with a thickness of approximately 20 μm, which served as the current collector layer, using the aforementioned loading amount. Subsequently, the insulating layer composition was applied to the active material layer composition, with the length of the overlapping region being approximately 0.5 mm or less and the average thickness of the insulating layer being (T L The coating was applied so that the thickness was approximately 20 μm.

[0198] Subsequently, the applied active material layer composition and insulating layer composition were dried with hot air at approximately 130°C for 1 minute, and the positive electrode was manufactured through a rolling process. Figure 9 is an SEM image of the positive electrode formed in this way (scale bar size: 50 μm, acceleration voltage: 2.0 kV, working distance: 8.1 mm, and magnification: ×400), showing that the average thickness of the active material layer is approximately 93 μm. In addition, the actual length of the superimposed region on this electrode was approximately 0.2 mm to 0.3 mm.

[0199] Furthermore, inspection of the electrodes after the above process revealed that no damage occurred to the current collector layer even after rolling, and no exposed areas of the current collector layer were found, as it stably overlapped the boundary region between the insulating layer and the active material layer.

[0200] Example 2. Determination of the maximum average thickness of the insulating layer An electrode was designed with an average active material layer thickness of approximately 46 μm and a maximum superimposed region length of 0.5 mm. According to the results of Test Example 1, the unit area required to ensure the aforementioned average thickness of 46 μm is 25 cm². 2 The loading amount of the active material layer composition per unit is approximately 220 mg.

[0201] The maximum average thickness of the insulating layer was then determined according to the method of Test Example 2. Specifically, by substituting 220 as the x value and 0.5 as the y value in the result of Figure 5 obtained in Test Example 2, the maximum average thickness of the insulating layer 30 (T max These are found in the range of approximately 25 μm to less than 40 μm.

[0202] Electrode manufacturing The electrodes were manufactured according to the design described above. As previously stated, when considering the results of Test Example 1 and Figure 3, the loading amount of the active material layer composition to ensure a thickness of 46 μm was approximately 220 mg / 25 cm². 2 It is to that extent.

[0203] The active material layer composition was applied to an aluminum foil (foil) with a thickness of approximately 20 μm, which served as the current collector layer, using the aforementioned loading amount. Subsequently, the insulating layer composition was applied to the active material layer composition, with the length of the overlapping region being approximately 0.5 mm or less and the average thickness of the insulating layer being (T L The coating was applied so that the thickness was approximately 20 μm.

[0204] Subsequently, the applied active material layer composition and insulating layer composition were dried with hot air at approximately 130°C for 1 minute, and the positive electrode was manufactured through a rolling process.

[0205] Furthermore, inspection of the electrodes after the above process revealed that no damage occurred to the current collector layer even after rolling, and no exposed areas of the current collector layer were found, as it stably overlapped the boundary region between the insulating layer and the active material layer.

[0206] Comparative Example 1. The composition for the insulating layer is the average thickness of the insulating layer (T L The positive electrode was manufactured in the same manner as in Example 1, except that the coating was applied to a thickness of 60 μm. Figure 10 shows the portion of the positive electrode manufactured according to Comparative Example 1 that includes the superposition region (SEM image (scale bar size: 50 μm, acceleration voltage: 2.0 kV, working distance: 8.1 mm and magnification: ×400)). Referring to Figure 10, it can be seen that in the portion corresponding to the superposition region, a fat edge phenomenon occurred where the combined thickness of the overlapping active material layer and insulating layer (approximately 121 μm) was thicker than the active material layer (approximately 93 μm).

[0207] In the case of the electrode in Comparative Example 1, severe damage occurred to the current collector layer after the rolling process. As a result, Comparative Example 1 suffered from reduced battery performance and safety issues.

[0208] Comparative Example 2. The composition for the insulating layer is the average thickness of the insulating layer (T L The positive electrode was manufactured in the same manner as in Example 1, except that the coating was applied to a thickness of 9 μm. In this case, the superposition region of the insulating layer and the active material layer was not effectively formed, and the current collector layer was exposed at the boundary, which was a significant disadvantage in terms of stability. [Explanation of Symbols]

[0209] 10: Current collector layer 20: Electrode active material layer 30: Insulating layer

Claims

1. Current collector layer, An electrode active material layer formed on the current collector layer, and The current collector layer includes an insulating layer formed on the current collector layer, The electrode active material layer and the insulating layer are formed side by side along a direction perpendicular to the normal direction of the surface of the current collector layer, and form overlapping regions that overlap each other. The thickness of the insulating layer satisfies the relationship shown in Equation 1 below. [Formula 1] T Ｌ ≦T Ｓ ×{a×exp(b×L)-c} In equation 1, T Ｌ is the thickness of the insulating layer, T Ｓ is the thickness of the electrode active material layer, L is the maximum length of the superimposed region, a is a number in the range of 0.55 to 0.95, b is a number in the range of -0.8 to -0.2, c is a number in the range of 0.001 to 0.004, and T Ｌ and the T Ｓ The unit of is μm, the unit of L is mm, L is in the range of 0.3 mm to 0.5 mm, and T Ｓ It is in the range of 50 μm to 300 μm. The following equation 2 is also satisfied, [Formula 2] 0.1 × T S ≤ T L An electrode in which, in Equation 2, T L is the thickness of the insulating layer and T S is the thickness of the electrode active material layer.

2. The following equation 3 is also satisfied, [Formula 3] T Ｓ =d×L Ｄ +e In equation 3, L Ｄ The loading amount of the electrode active material layer (mg / 25cm) is the loading amount (mg / 25cm). ２ The electrode according to claim 1, wherein the unit is (, d is a number in the range of 0.1 to 0.2, and e is a number in the range of 10 to 16.

3. The electrode according to claim 1, wherein the electrode active material layer contains polyvinylidene fluoride as a binder, and the insulating layer contains styrene-butadiene rubber or styrene-butadiene latex as a binder.

4. The electrode according to claim 1, wherein the electrode active material layer contains polyvinylidene fluoride as a binder, and the insulating layer contains polyvinylidene fluoride as a binder.

5. The electrode according to claim 3 or 4, further comprising a ceramic in the insulating layer.

6. The aforementioned ceramic is AlO(OH), Al ２ O ３ SiO ２ , TiO ２ , SnO ２ , CEO ２ , MgO, NiO, CaO, ZnO, ZrO ２ , Y ２ O ３ SrTiO ３ , BaTiO ３ and Mg(OH) ２ The electrode according to claim 5, which is one or more selected from the group consisting of the following.

7. The steps include applying the electrode active material layer composition onto the current collector layer, and A method for manufacturing an electrode, comprising the step of applying an insulating layer composition onto a current collector layer, The electrode active material layer composition and the insulating layer composition are applied such that the electrode active material layer and the insulating layer are formed side by side along a direction perpendicular to the normal direction of the surface of the current collector layer, forming overlapping regions that overlap each other. The insulating layer composition is applied to a thickness satisfying the following formula 4, T in equation 4 below ｍａｘ This is determined by the following formula 5, [Formula 4] T Ｌ ’≦T ｍａｘ In equation 4, T ｍａｘ is the maximum average thickness of the insulating layer, T Ｌ ' is the coating thickness of the insulating layer composition, [Formula 5] T ｍａｘ =T ａ ×{a×exp(b×L)-c} In equation 5, T ａ is the average thickness of the electrode active material layer, L is the maximum length of the superimposed region, a is a number in the range of 0.55 to 0.95, b is a number in the range of -0.8 to -0.2, c is a number in the range of 0.001 to 0.004, and T Ｌ A method for manufacturing an electrode, wherein the unit of ' is μm, the unit of L is mm, and L is within the range of 0.3 mm to 0.5 mm.

8. The method for manufacturing an electrode according to claim 7, wherein the electrode active material layer composition comprises polyvinylidene fluoride as a binder, and the insulating layer composition comprises styrene-butadiene rubber or styrene-butadiene latex as a binder.

9. The method for manufacturing an electrode according to claim 7, wherein the electrode active material layer composition comprises polyvinylidene fluoride as a binder, and the insulating layer composition comprises polyvinylidene fluoride as a binder.

10. The method for manufacturing an electrode according to claim 8 or 9, wherein the insulating layer composition further comprises a ceramic.

11. The aforementioned ceramic is AlO(OH), Al ２ O ３ SiO ２ , TiO ２ , SnO ２ , CEO ２ , MgO, NiO, CaO, ZnO, ZrO ２ , Y ２ O ３ SrTiO ３ , BaTiO ３ and Mg(OH) ２ A method for manufacturing an electrode according to claim 10, wherein one or more of the following are selected from the group consisting of

12. Including a negative electrode, a positive electrode, and a separator, The negative electrode and the positive electrode are stacked with the separator in between. An electrode assembly wherein at least one of the negative electrode and the positive electrode is the electrode described in claim 1.

13. A secondary battery comprising the electrode described in claim 1.

Images