Electrode assembly with short circuit prevention structure

Abstract

The present invention provides an electrode assembly having a structure capable of preventing a phenomenon in which ends of a positive electrode plate and a negative electrode plate partitioned by a separator are short-circuited. The electrode assembly has a structure in which one or more first electrode plates, separators, and second electrode plates are stacked, and the first electrode plate has a first electrode tab portion on one widthwise side thereof on which a first active material is not applied, and the first electrode tab portion extends outward in the widthwise direction further than the separator at one widthwise side end of the electrode assembly, and an insulating coating is applied to a slit surface of the second electrode plate disposed adjacent to the first electrode tab portion through the separator at one side end of the electrode assembly. The insulating coating is applied after the second active material is applied to the second electrode plate and slit, and is applied before the first electrode plate, the second electrode plate, and the separator are stacked.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0007761 dated January 19, 2022, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly, and more particularly, to an electrode assembly having a structure capable of preventing a short circuit between ends of a positive electrode plate and a negative electrode plate separated by a separator. [Background technology]

[0003] As technology for mobile devices develops and demand increases, the demand for secondary batteries as an energy source is growing rapidly. In recent years, the use of secondary batteries as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs) is becoming a reality, and there is a high demand for lithium secondary batteries, which have high energy density, high discharge voltage, and stable output.

[0004] Secondary batteries are also classified according to the structure of the electrode assembly having a positive electrode / separator / negative electrode structure. Representative examples include a jelly roll (wound type) electrode assembly in which long sheet-like positive and negative electrodes are wound with a separator interposed therebetween, a stack type electrode assembly in which a number of positive and negative electrodes cut into units of a predetermined size are stacked in sequence with a separator interposed therebetween, and a stack folding type electrode assembly in which unit cells, e.g., bi-cells or full cells, in which positive and negative electrodes of a predetermined unit are stacked with a separator interposed therebetween, are wound up.

[0005] In the electrode assemblies having various structures, the positive plate includes a positive current collector region in which a positive active material is applied to both sides of a positive metal foil constituting the positive plate, and a positive tab portion provided on one widthwise side of the positive current collector and in which the positive metal foil is not coated with the positive active material, and the negative plate includes a negative current collector region in which a negative active material is applied to both sides of a negative metal foil constituting the negative plate, and a negative tab portion provided on one widthwise side of the negative current collector and in which the negative metal foil is not coated with the negative active material.

[0006] A separator is interposed between the positive and negative electrodes.

[0007] With the separator interposed, the positive electrode tab portion and the negative electrode tab portion may extend outward beyond the separator in a width direction, and the positive electrode tab portion may protrude to one side in the width direction and the negative electrode tab portion may protrude to the other side in the width direction.

[0008] With this structure, when the positive electrode tab portion or the negative electrode tab portion is bent in the process of connecting the electrode tabs, it may come into contact with the negative electrode current collector portion or the positive electrode current collector portion arranged via the separation membrane, causing a short circuit.

[0009] For this reason, a manufacturing method has been proposed in which the positive electrode tab portion and / or the negative electrode tab portion are insulatingly coated as disclosed in Patent Document 1 (KR2021-0011584A), or separation membranes existing on both sides of the other end of the positive electrode current collector and / or one end of the negative electrode current collector are joined so that the other end of the positive electrode current collector and / or one end of the negative electrode current collector are not exposed as disclosed in Patent Document 2 (KR2021-0027023A).

[0010] However, such short circuit prevention structures have problems in that they have little short circuit prevention effect, so there is still a risk of short circuit, or a cumbersome processing step must be added to fabricate the electrode assembly by stacking the positive electrode plate, the separator, and the negative electrode plate. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to provide an electrode assembly capable of preventing a short circuit between a positive electrode plate and a negative electrode plate, and a manufacturing method thereof.

[0012] An object of the present invention is to provide an electrode assembly and a manufacturing method thereof that realizes a structure for preventing a short circuit between a positive electrode plate and a negative electrode plate of the electrode assembly without adding a cumbersome additional process to the manufacturing method of the electrode assembly.

[0013] The present invention aims to provide an electrode assembly and a manufacturing method thereof, which can maintain the dimensions and shape of the electrode assembly structure before application of a short-circuit prevention structure between positive and negative electrode plates of the electrode assembly.

[0014] The technical object of the present invention is not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned above can be understood from the following description and can be more clearly understood from the embodiments of the present invention. In addition, it is easy to understand that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0015] The present invention provides a structure of an electrode assembly in which at least one each of a first electrode plate, a separator, and a second electrode plate are stacked, and a manufacturing method thereof.

[0016] In order to solve the above-mentioned problems, the present invention forms an insulating coating on the slit surface of the first electrode plate and / or the slit surface of the second electrode plate.

[0017] The electrode assembly may have a structure in which a first current collecting portion of a first electrode plate and a second electrode tab portion of a second electrode plate face each other across an edge of a separator.

[0018] The electrode assembly may have a structure in which the second current collecting portion of the second electrode plate and the first electrode tab portion of the first electrode plate face each other across an edge of a separator.

[0019] The first electrode plate may include a first current collecting portion (first coated portion) having a first active material applied to both sides of a first metal foil, and a first electrode tab portion (first uncoated portion) on one widthwise side thereof where the first active material is not applied.

[0020] The second electrode plate may include a second current collecting portion (second coated portion) having a second active material applied to both sides of a second metal foil, and a second electrode tab portion (second uncoated portion) on the other widthwise side thereof where the second active material is not applied.

[0021] The first electrode tab portion may extend outwardly further toward one widthwise side than the separator at one widthwise end of the electrode assembly.

[0022] An insulating coating is applied to a slit surface of the second electrode plate disposed adjacent to the first electrode tab portion with the separator interposed therebetween at one side end of the electrode assembly.

[0023] The slit surface can be formed by slitting the second current collecting portion of the second electrode plate.

[0024] The insulating coating may cover the entire slit surface of the second electrode plate in a stacking direction of the electrode assembly.

[0025] The insulating coating may be connected to a slit surface of the second electrode plate and may further cover a portion of a first surface of the second electrode plate facing the separator.

[0026] The insulating coating may be connected to a slit surface of the second electrode plate and may further cover a portion of a second surface of the second electrode plate facing the first surface.

[0027] A portion of the first electrode plate facing the portion on which the insulating coating is formed via a separator may be a first electrode tab portion, so that even if the thickness of the insulating coated portion of the second electrode plate is thicker than the thickness of the second current collecting portion of the second electrode plate, the stacked structure of the electrode assembly can be maintained parallel.

[0028] A corner portion of the second active material disposed on the slit surface of the second current collecting portion may have a processed surface whose thickness is gradually reduced.

[0029] The insulating coating may cover the slit surface and the processed surface, thereby minimizing the deviation between the thickness of the second current collecting portion of the second electrode plate and the thickness of the insulating coating portion, thereby maintaining the stacked structure of the electrode assembly parallel.

[0030] The processed surface can be formed by the slitting step. The slitting step may be a method in which the edge of the second current collecting part is supported by a lower blade and pressed by an upper blade to cut it out.

[0031] The processed surface can be formed by a further pressing step after the slitting step. The pressing step may be a pressing roll step.

[0032] The processed surface can be processed by a roller that transports the second electrode plate after the slitting step.

[0033] These rollers may be pinch rollers that support the slit surface of the second electrode plate.

[0034] The pinch rollers can stand the second electrode plate, which is transported in the longitudinal direction, in a horizontal position.

[0035] The pinch roller may include a central guide surface that supports the slit surface, and a central guide surface whose diameter gradually increases from both side ends of the central guide surface toward the outside.

[0036] The working surface may be defined by the central guide surface.

[0037] The insulating coating can be applied to the slit surface located at the lower end of the standing second electrode plate.

[0038] The insulating coating may be formed by spray coating.

[0039] The insulating coating can be formed by dipping the slit surface in an insulating liquid.

[0040] The insulating coating liquid for the insulating coating may be a colloidal solution in which ceramic particles are dispersed.

[0041] The insulating coating can be performed by applying an insulating coating liquid to the slit surface and then curing the liquid.

[0042] The second electrode plate, after being formed with the insulating coating, may be wound into a roll for storage. That is, the present invention illustrates a method in which, before laminating the first electrode plate, the separator, and the second electrode plate, a second active material is applied to a second metal foil, one end of the second electrode plate in the width direction is slit, and an insulating coating is applied to the slit surface.

[0043] The first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate.

[0044] Alternatively, the first electrode plate may be a negative electrode plate and the second electrode plate may be a positive electrode plate.

[0045] The second current collecting portion may have a width greater than a width of the first current collecting portion, such that a slit surface of the second current collecting portion faces the first electrode tab portion via a separator.

[0046] Alternatively, a width of the second current collecting portion may be smaller than a width of the first current collecting portion, and a slit surface of the first current collecting portion may face the second electrode tab portion via a separator.

[0047] The present invention further provides a method for manufacturing the electrode assembly.

[0048] This includes a second electrode plate preparation step of forming a second current collector by applying a second active material to both sides of a second metal foil, and slitting the other end of the second current collector to form a slit surface.

[0049] The method further includes forming an insulating coating on the slit surface.

[0050] The insulating coating can be applied by spray coating or dip coating.

[0051] Then, a first electrode plate, a separator, and the second electrode plate are stacked together.

[0052] The method for manufacturing the electrode assembly may further include winding the stacked first electrode plate, separator, and second electrode plate around a winding shaft to manufacture a jelly roll type electrode assembly.

[0053] The method may further include bending the first electrode tab portions exposed at widthwise ends of the electrode assembly wound in a jelly roll shape in a radial direction to form bent surfaces, thereby manufacturing a jelly roll type electrode assembly.

[0054] Even if the first electrode tab portion is bent, the adjacent end of the second electrode plate has an insulating coating, so that a short circuit between the first electrode tab portion and the slit surface of the second electrode plate can be prevented.

[0055] Alternatively, the method for manufacturing the electrode assembly may further include stacking a plurality of unit cells, each of which includes the first electrode plate, a separator, and a second electrode plate, to form a stack, thereby manufacturing a stack-type electrode assembly.

[0056] Alternatively, the method may further include manufacturing a unit cell by stacking the first electrode plate, the separator, and the second electrode plate, placing the unit cell on a plurality of folding separators to laminate them, and then folding the laminated folding separators into a stack-folded shape, thereby manufacturing a stack-folded type electrode assembly. Effect of the Invention

[0057] According to the electrode assembly structure and manufacturing method thereof according to the present invention, a structure capable of preventing a short circuit between the positive and negative electrode plates can be easily applied.

[0058] According to the present invention, a structure for preventing a short circuit between a positive electrode plate and a negative electrode plate of an electrode assembly is embodied, and a cumbersome additional process is not required in a manufacturing method of the electrode assembly.

[0059] According to the present invention, even if a short-circuit prevention structure for a positive electrode plate and a negative electrode plate of an electrode assembly is applied, the dimensions and shape of the electrode assembly structure before the application of the short-circuit prevention structure can be maintained as they are.

[0060] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief description of the drawings]

[0061] [Figure 1] 1 is a cross-sectional view showing a portion of an electrode assembly according to a first embodiment of the present invention. [Diagram 2] 2 is an enlarged view of one widthwise end portion of the electrode assembly of FIG. 1. [Diagram 3]2 is a view showing a state in which a first electrode tab portion of the electrode assembly of FIG. 1 is bent; [Figure 4] 2 is a diagram showing a manufacturing process of the electrode assembly of FIG. 1; [Diagram 5] 2 is a diagram showing a manufacturing process of the electrode assembly of FIG. 1; [Figure 6] 11 is an enlarged view of one widthwise end portion of an electrode assembly according to a second embodiment of the present invention. FIG. [Figure 7] 13 is an enlarged view of one widthwise end portion of an electrode assembly according to a third embodiment of the present invention. FIG. [Figure 8] 13 is an enlarged view of one widthwise end portion of an electrode assembly according to a fourth embodiment of the present invention. FIG. [Figure 9] FIG. 13 is a cross-sectional view of a jelly-roll type electrode assembly according to a fifth embodiment of the present invention. [Figure 10] FIG. 13 is a cross-sectional view of a stacked electrode assembly according to a sixth embodiment of the present invention. [Figure 11] FIG. 13 is an exploded view of a stack-folding type electrode assembly according to a seventh embodiment of the present invention. [Figure 12] 4 is a simplified diagram of a second electrode plate manufacturing apparatus according to the present invention. [Figure 13] This is a cross section taken along line XIII-XIII in FIG. [Figure 14] This is a cross section taken along line XIV-XIV in FIG. [Figure 15] This is a cross section taken along line XV-XV in FIG. [Figure 16] This is a cross section taken along line XVI-XVI in Figure 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] The above-mentioned objects, features and advantages will be described in detail below with reference to the accompanying drawings, so that a person having ordinary skill in the art to which the present invention pertains can easily implement the technical idea of ​​the present invention. In describing the present invention, if a detailed description of a known technology according to the present invention is deemed to make the gist of the present invention unclear, the detailed description will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0063] Although the terms "first", "second", etc. are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it is understood that a first component may also be a second component unless otherwise specified.

[0064] Unless otherwise specified to the contrary in the entire specification, each element may be singular or plural.

[0065] Hereinafter, when an arbitrary structure is arranged on the "top (or bottom)" of a component or "above (or below)" a component, it means that the arbitrary structure is not only arranged in contact with the upper surface (or lower surface) of the component, but also that other structures may be interposed between the component and the arbitrary structure arranged on (or below) the component.

[0066] In addition, when a component is described as being "coupled," "coupled," or "connected" to another component, it should be understood that the components may be directly coupled or connected to each other, but that other components may be "intervening" between each component, or each component may be "coupled," "coupled," or "connected" via other components.

[0067] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "include" should not be interpreted as including all of the multiple components or multiple steps described in the specification, and should be interpreted as including some of the components or steps that may not be included or may include additional components or steps.

[0068] Throughout the specification, "A and / or B" means A, B, or A and B, unless otherwise specified, and "C to D" means C or more and D or less, unless otherwise specified.

[0069] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0070] [First Example] 1 to 5, the electrode assembly of the first embodiment includes at least one first electrode plate 10, one separator 30, and one second electrode plate 20 stacked together. For ease of explanation, FIGS. 1 to 5 show a structure in which one each of the first electrode plate 10, the separator 30, and the second electrode plate 20 are stacked together. The electrode assembly described in the first embodiment can be finally manufactured into an electrode assembly by being processed into a jelly roll shape of the fifth embodiment described later with reference to FIG. 9, a stack shape of the sixth embodiment described later with reference to FIG. 10, or a stack folding shape of the seventh embodiment described later with reference to FIG. 11.

[0071] The first electrode plate 10 may include a first current collecting portion 13 having a first active material 12 applied to both sides of a first metal foil 11, and a first electrode tab portion 14 on one widthwise side of the first current collecting portion 13 where the first active material 12 is not applied.

[0072] The second electrode plate 20 may include a second current collecting portion 23 having a second active material 22 applied to both sides of a second metal foil, and a second electrode tab portion 24 on the other widthwise side of the second current collecting portion 23 where the second active material is not applied.

[0073] The first electrode plate 10 may be a positive electrode plate and the second electrode plate 20 may be a negative electrode plate, but the reverse is of course also possible.

[0074] In the present invention, the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate may be any active material known in the art without any limitations.

[0075] The positive electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2x Lithium manganese oxides (LiMnO2), such as LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides, such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x O2 (where M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x=0.01-0.3); 2-x M x Lithium intercalation materials include, but are not limited to, lithium manganese composite oxides represented as LiMnO2 (wherein M is Co, Ni, Fe, Cr, Zn, or Ta, and x is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the lithium in the chemical formula is replaced with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, or composite oxides formed by a combination of these.

[0076] The positive electrode current collector has a thickness of, for example, 3 to 500 μm. The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and for example, stainless steel, aluminum, nickel, titanium, plastic carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. The electrode current collector can be formed with fine irregularities on its surface to increase the adhesive strength of the positive electrode active material, and can be in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0077] The positive electrode active material particles may further contain a conductive material. The conductive material is added, for example, in an amount of 1 to 50% by weight based on the total weight of the mixture containing the positive electrode active material. The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity, and examples of the conductive material that can be used include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0078] The negative electrode is fabricated by coating and drying negative active material particles on a negative current collector, and may further include components such as the conductive material, binder, and solvent described above, as necessary.

[0079] The negative electrode current collector has a thickness of, for example, 3 to 500 μm. These negative electrode current collectors are not particularly limited as long as they do not cause a chemical change in the battery and have conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, plastic carbon, those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the binding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabric bodies, etc.

[0080] The negative electrode active material is, for example, carbon such as graphitizable carbon and graphite-based carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’yO z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials, etc. can be used.

[0081] The binder polymer usable in the electrode is a component that aids in binding between the electrode active material particles and the conductive material and between the electrode current collector, and is added in an amount of, for example, 1 to 50 wt % based on the total weight of the mixture including the electrode active material. Examples of these binder polymers include polyvinylidene fluoride-co-hexafluoropropylene (PVdF), polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. The binder polymer may be any one selected from the group consisting of cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxyl methyl cellulose, or a mixture of two or more of these, but is not limited thereto.

[0082] Non-limiting examples of the solvent used in the preparation of the electrode include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof, etc. These solvents provide an appropriate level of viscosity so that a slurry coating layer can be formed at a desired level on the surface of the electrode current collector.

[0083] The negative electrode comprises a current collector; and a negative electrode active material layer located on at least one surface of the current collector and including a negative electrode active material, a binder polymer, and a conductive material, the negative electrode active material layer including a lower layer region in contact with the current collector and an upper layer region in contact with the lower layer region and extending to a surface of the negative electrode active material layer, the lower layer region and the upper layer region each independently including at least one of graphite and a silicon-based compound as the negative electrode active material.

[0084] The lower layer region may include natural graphite as a negative electrode active material, and the upper layer region may include artificial graphite as a negative electrode active material.

[0085] The lower layer region and the upper layer region may each independently further include a silicon-based compound as a negative electrode active material.

[0086] The silicon-based compound is SiO x (0≦x≦2) and SiC.

[0087] According to an embodiment of the present invention, the negative electrode may be manufactured by coating and drying a lower layer slurry containing a lower layer negative electrode active material on a current collector to form a lower layer region, and then coating and drying an upper layer slurry containing an upper layer negative electrode active material on the lower layer region to form an upper layer region.

[0088] According to an embodiment of the present invention, the negative electrode may be manufactured by a method including the steps of: preparing a lower layer slurry including a lower layer negative electrode active material; and an upper layer slurry including an upper layer negative electrode active material; coating one surface of a negative electrode current collector with the lower layer slurry, and simultaneously or after a predetermined time, coating the upper layer slurry on the lower layer slurry; and simultaneously drying the coated lower layer slurry and upper layer slurry to form an active material layer.

[0089] In the latter case, a mixed region (intermixing) in which different types of active materials are mixed with each other may be present at the contact portion between the lower layer region and the upper layer region in the negative electrode. This is because, when an active material layer is formed by simultaneously or successively coating a lower layer slurry containing a lower layer negative electrode active material and an upper layer slurry containing an upper layer negative electrode active material on a current collector and then drying them simultaneously, a predetermined mixed region is generated at the interface where the lower layer slurry and the upper layer slurry contact each other before drying, and then the mixed region is formed into a layer shape as the mixed region while drying.

[0090] In the negative electrode active material layer according to an embodiment of the present invention, the weight ratio (or the ratio of loading amount per unit area) of the upper layer region to the lower layer region may be 20:80 to 50:50, specifically, 25:75 to 50:50.

[0091] The thicknesses of the lower and upper regions of the negative electrode active material layer of the present invention may not be completely equal to the thicknesses of the coated lower layer slurry and the coated upper layer slurry, but the thickness ratio of the lower and upper regions of the negative electrode active material layer of the present invention finally obtained as a result of the drying or selective rolling process may be equal to the thickness ratio of the coated lower layer slurry and the coated upper layer slurry.

[0092] The first slurry is coated, and the second slurry is coated on the first slurry at the same time or after a predetermined time interval, and according to an embodiment of the present invention, the predetermined time difference may be 0.6 seconds or less, or 0.02 seconds to 0.6 seconds, or 0.02 seconds to 0.06 seconds, or 0.02 seconds to 0.03 seconds. Since the time difference occurring when coating the first slurry and the second slurry is caused by the coating equipment, it is more preferable to coat the first slurry and the second slurry at the same time. The method of coating the second slurry on the first slurry can use an apparatus such as a double slot die.

[0093] The step of forming the active material layer may further include a step of rolling the active material layer after the drying step, wherein the rolling may be performed by a method commonly used in the art, such as roll pressing, at a pressure of 1 to 20 MPa and a temperature of 15 to 30°C.

[0094] The step of simultaneously drying the coated lower layer slurry and upper layer slurry to form an active material layer may be carried out by a method commonly used in the art using a combination of a hot air dryer and an infrared dryer.

[0095] The weight % of the first binder polymer in the solid content of the lower layer slurry may be equal to or greater than the weight % of the second binder polymer in the solid content of the upper layer slurry. According to an embodiment of the present invention, the weight % of the first binder polymer in the solid content of the lower layer slurry may be 1.0 to 4.2 times, 1.5 to 3.6 times, or 1.5 to 3 times greater than the weight % of the second binder polymer in the solid content of the upper layer slurry.

[0096] In this case, when the weight percentage of the first binder in the coated lower layer slurry and the weight percentage of the second binder in the coated upper layer slurry satisfy these ranges, the amount of binder in the lower layer region is not too small to cause detachment of the electrode layer, and the amount of binder in the upper layer region is not too large to reduce the resistance of the upper layer of the electrode, which is advantageous for fast charging performance.

[0097] The weight percentage of the first binder polymer in the solid content of the lower layer slurry may be 2 to 30 weight%, or 5 to 20 weight%, or 5 to 20 weight%, and the weight percentage of the second binder polymer in the solid content of the upper layer slurry may be 0.5 to 20 weight%, or 1 to 15 weight%, or 1 to 10 weight%, or 2 to 5 weight%.

[0098] The total ratio (wt %) of the first binder polymer and the second binder polymer to the total solid content of the lower layer slurry and the upper layer slurry may be 2 to 20 wt % or 5 to 15 wt %.

[0099] The electrode assembly is manufactured by alternately stacking the first electrode plates 10 and the second electrode plates 20 with the separator 30 interposed therebetween. Then, the first electrode tab portions 14 of the stacked first electrode plates 10 protrude further toward one widthwise side than the separator 30, and the second electrode tab portions 24 of the stacked second electrode plates 20 protrude further toward the other widthwise side than the separator 30.

[0100] In the embodiment, the first electrode plate 10 and the second electrode plate 20 are illustrated as having an electrode tab portion to which no active material is applied. However, the present invention is not limited to such a structure. For example, the first electrode plate 10 may have a first electrode tab portion 14, but the second electrode plate 20 may not have a second electrode tab portion, and the second electrode plate 20 may have a second electrode tab portion 24, but the first electrode plate 10 may not have a first electrode tab portion.

[0101] The electrode assembly of the embodiment has a structure in which the second current collecting portion 23 of the second electrode plate 20 and the first electrode tab portion 14 of the first electrode plate 10 face each other across one widthwise edge of the separator 30 .

[0102] The electrode assembly may have a structure in which the first current collecting portion 13 of the first electrode plate 10 and the second electrode tab portion of the second electrode plate 20 face each other across the other widthwise edge of the separator 30.

[0103] In the present invention, an insulating coating 26 is formed on the slit surface of the first electrode plate 10 and / or the slit surface 237 of the second electrode plate 20. In the embodiment, a structure in which the insulating coating 26 is formed only on the slit surface 237 of the second electrode plate 20, and the slit surface 237 of the first electrode plate 10 is not coated with an insulating coating is exemplified.

[0104] The insulating coating 26 is provided on a slit surface 237 of the second electrode plate 20 disposed adjacent to the first electrode tab portion 14 with the separator 30 interposed therebetween at one side end of the electrode assembly.

[0105] According to an embodiment, the second electrode plate 20 may be larger in the width direction than the first electrode plate 10. According to an embodiment, the second current collecting portion 23 may be larger in the width direction than the first current collecting portion 13. As a result, the possibility of a short circuit between the first electrode tab portion 14 and the second current collecting portion 23 when the first electrode tab portion 14 is bent or folded may be greater than the possibility of a short circuit between the second electrode tab portion 24 and the first current collecting portion 13 when the second electrode tab portion 24 is bent or folded.

[0106] The other end of the width direction of the first electrode plate 10 may be formed by applying a first active material 12 to both sides of a first metal foil 11 and then slitting the first metal foil 11 to form a slit surface.

[0107] At one end of the width direction of the second electrode plate 20, a second active material 22 may be applied to both sides of a second metal foil 21, and then the second metal foil 21 may be slit to form a slit surface 237.

[0108] The insulating coating 26 may be applied to the slit surface 237 of the second electrode plate 20 after the second electrode plate 20 is slit as shown in FIG.

[0109] The insulating coating material for the insulating coating 26 may be a colloidal solution in which ceramic insulating particles are dispersed. The insulating coating material is applied to the slit surface 237 and cured by a method such as heating and drying, to complete the insulating coating 26.

[0110] As shown in FIG. 5, the first electrode plate 10, the separator 30, and the second electrode plate 20 having the insulating coating 26 thereon are stacked to fabricate an electrode assembly.

[0111] The insulating coating 26 may be in a state where it has already been coated before the second electrode plate 20 is laminated on the separator 30. The separator 30 may be provided in a sheet form.

[0112] According to the first embodiment, the insulating coating 26 may cover the entire slit surface 237 of the second electrode plate 20 in the stacking direction of the electrode assembly. Then, both sides of the second electrode plate 20 may be covered by the separator 30 stacked thereon, and one end of the width direction of the second electrode plate 20 may be covered by the insulating coating 26.

[0113] As a result, even if the first electrode tab portion 14 is bent as shown in FIG. 3, the phenomenon in which the first electrode tab portion 14 comes into contact with the slit surface 237 of the second electrode plate 20 and a short circuit occurs can be fundamentally prevented.

[0114] [Second Example] Hereinafter, a second embodiment of an electrode assembly according to the present invention will be described with reference to Fig. 6. In describing the second embodiment, differences from the first embodiment will be mainly described. Therefore, matters that are not specifically described for the second embodiment can be understood from the first embodiment and other embodiments.

[0115] The insulating coating 26 applied to the electrode assembly according to the second embodiment covers the entire slit surface 237 of the second electrode plate 20 in the stacking direction of the electrode assembly, and further covers a portion of the first surface of the second electrode plate 20 facing the separator 30 in a form connected thereto.

[0116] A portion of the first electrode plate facing the portion where the insulating coating 26 is formed through the separator 30 may be the first electrode tab portion 14. That is, the first active material 12 is not applied to the portion of the first electrode plate 10 that faces the insulating coating 26 and the separator 30, so that a small amount of space can be provided between the first electrode tab portion 14 and the separator 30.

[0117] As a result, even if the thickness of the portion of the second electrode plate 20 covered with the insulating coating 26 is thicker than the thickness of the second current collecting portion 23 of the second electrode plate 20, there is a possibility that the separator 30 may be offset and deformed toward the first electrode tab portion 14. As a result, even if the portion of the insulating coating 26 of the second electrode plate 20 is thicker than other portions of the second electrode plate 20, the stacked structure of the electrode assembly can be maintained generally parallel.

[0118] In addition, if the insulating coating 26 further covers a portion of the first surface of the second electrode plate 20 facing the separator 30, the covering portion can more reliably prevent a short circuit between the first electrode tab portion 14 and the second electrode plate 20 even if the first electrode tab portion 14 is caught between the second electrode plate 20 and the separator 30 during the process of winding the electrode assembly into a jelly roll and bending the first electrode tab portion 14 as in the fifth embodiment described below. This is the same in the third and fourth embodiments described below.

[0119] [Third Example] Hereinafter, a third embodiment of an electrode assembly according to the present invention will be described with reference to Fig. 7. In describing the third embodiment, differences from the second embodiment will be mainly described.

[0120] The insulating coating 26 applied to the electrode assembly according to the third embodiment covers the entire slit surface 237 of the second electrode plate 20 in the stacking direction of the electrode assembly, and in a connected form, covers a portion of the first surface of the second electrode plate 20 and further covers a portion of the second surface, which is the opposite surface to the first surface.

[0121] For ease of explanation, FIG. 7 does not show a configuration in which another separator and a first electrode plate are stacked on the upper part of the second electrode plate 20. However, an actual electrode assembly may have a configuration in which a plurality of first electrode plates 10 and second electrode plates 20 are alternately arranged with separators 30 interposed therebetween, as shown in FIG. 10.

[0122] As described in the second embodiment, the insulating coating 26 covering the end of the first surface makes the second electrode plate 20 thicker at that portion than the other portions, but still allows the layered structure of the electrode assembly to be maintained generally parallel. Similarly, the insulating coating 26 covering the end of the second surface makes the second electrode plate 20 thicker at that portion than the other portions, but still allows the layered structure of the electrode assembly to be maintained generally parallel.

[0123] [Fourth Example] Hereinafter, a fourth embodiment of the electrode assembly according to the present invention will be described with reference to Fig. 8. In describing the fourth embodiment, differences from the third embodiment will be mainly described.

[0124] When one side end of the second electrode plate 20 is slit to machine the slit surface 237, the corner portion of the slit surface 237 may form a machined surface 225 as shown in FIG.

[0125] The slitting is performed by supporting the lower part of the cut part with the lower blade and applying pressure to the upper part of the cut part with the upper blade, and at this time, the second active material 22 applied to the second electrode plate 20 is pushed or rolled up by the upper and lower blades to form a processed surface 225. These processed surfaces 225 may be in a chamber (chamfered) shape as shown, or in a pellet (round) shape.

[0126] As the slit processing method, various methods can be applied, such as not only a mechanical processing method using a sharp blade but also an optical processing method using a laser.

[0127] The processing surface 225 may be performed during the process of transferring the second electrode plate 20 after the slit processing.

[0128] After one side end of the second electrode plate 20 is slit, in order to apply an insulating coating to that portion, the posture of the second electrode plate 20, which was transferred in a lying position, is changed to an upright position for transfer, and an insulating coating can be applied to the slit surface 237 located at the lower end of the upright second electrode plate 20.

[0129] When the second electrode plate 20 is erected, for example, a pinch roller can be used to support the end of the second electrode plate 20. Then, the second electrode plate 20 is transferred from a horizontal transfer roller that is in rolling contact with the surface of the second electrode plate 20 to the pinch roller, and the posture of the second electrode plate 20 is gradually erected.

[0130] The pinch roller supporting the lower end of the second electrode plate 20 may form the processed surface 225 by pressing the corner portions of the active material layer of the second electrode plate 20 when transporting the second electrode plate 20.

[0131] Then, when insulating coating the slit surface 237 and the adjacent first and second surfaces, the insulating coating 26 is applied to the area where the thickness is thinned by the processed surface 225, and the phenomenon in which the thickness of the second electrode plate 20 becomes further thick due to the insulating coating 26 can be minimized.

[0132] In addition, after the slit processing, a pressure roll can be used to further intentionally form a processed surface 225 at the corner portion of the slit surface 237, so that the processed surface 225 can be further formed at the corner portion of the slit surface 237.

[0133] As a result, the thickness uniformity of the second electrode plate 20 can be ensured despite the insulating coating 26, and the laminated structure of the electrode assembly can be maintained generally parallel.

[0134] [Fifth Example] Hereinafter, a fifth embodiment of an electrode assembly according to the present invention will be described with reference to FIG.

[0135] The electrode assembly 1 may be manufactured in the form of a jelly roll by stacking the first electrode plate 10, the separator 30, the second electrode plate 20, and the separator 30 in a form having a predetermined width and extending long in the winding direction, and winding the stack around a winding shaft. In this case, the first electrode tab portion 14 and the second electrode tab portion 24 may be exposed at one end (upper part of the drawing) and the other end (lower part of the drawing) of the cylindrical electrode assembly.

[0136] These electrode tabs may be bent radially inward as shown in the drawings, or may be bent in the opposite direction, i.e., radially outward, to the flat bent surfaces formed by bending the electrode tabs in this manner, to which a current collecting plate (not shown) may be attached by welding or other methods.

[0137] In the embodiment, a structure in which the first electrode tab portion 14 is bent radially inward is illustrated. Even if the first electrode tab portion 14 is bent in this manner, the adjacent end portion of the second electrode plate 20 has the insulating coating 26, so that a short circuit between the first electrode tab portion 14 and the slit surface of the second electrode plate 20 can be prevented.

[0138] Of course, the second electrode tab portion 24 shown in Fig. 9 may also be bent radially inward or outward, or the electrode tab portion may be connected to the current collecting plate without being bent.

[0139] These jelly roll type electrode assemblies 1 can be used in the manufacture of secondary batteries in a form housed in a cylindrical battery can (not shown).

[0140] Preferably, these cylindrical secondary batteries may be, for example, cylindrical secondary batteries having a form factor ratio (defined as the diameter of a cylindrical battery secondary cell divided by its height, i.e., the ratio of the diameter (Φ) to the height (H)) greater than approximately 0.4.

[0141] Here, the form factor refers to values ​​indicating the diameter and height of a cylindrical secondary battery. The cylindrical secondary battery according to an embodiment of the present invention may be, for example, a 46110 cell, a 48750 cell, a 48110 cell, a 48800 cell, or a 46800 cell. In the numerical value indicating the form factor, the first two digits indicate the diameter of the cell, the next two digits indicate the height of the cell, and the final digit 0 indicates that the cross section of the cell is circular.

[0142] When an electrode assembly having a tabless structure is applied to a cylindrical secondary battery having a form factor ratio exceeding 0.4, the electrode tab portion is easily broken due to a large radial stress when the electrode tab portion is bent. Also, when a current collecting plate is welded to the bent surface of the electrode tab portion, the number of overlapping layers of the electrode tab portion must be increased sufficiently to ensure sufficient welding strength and reduce resistance. These requirements can be met by the electrode plate and electrode assembly according to the above-described embodiment of the present invention.

[0143] The secondary battery according to one embodiment of the present invention may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of approximately 46 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0144] A secondary battery according to another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of approximately 48 mm, a height of approximately 75 mm, and a form factor ratio of 0.640.

[0145] A secondary battery according to yet another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of approximately 48 mm, a height of approximately 110 mm, and a form factor ratio of 0.418.

[0146] A secondary battery according to yet another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of approximately 48 mm, a height of approximately 80 mm, and a form factor ratio of 0.600.

[0147] A secondary battery according to yet another embodiment may be a cylindrical secondary battery having a substantially cylindrical cell with a diameter of approximately 46 mm, a height of approximately 80 mm, and a form factor ratio of 0.575.

[0148] Conventionally, secondary batteries with a form factor ratio of approximately 0.4 or less have been used. That is, conventionally, for example, 18650 cells, 21700 cells, etc. have been used. In the case of an 18650 cell, its diameter is approximately 18 mm, its height is approximately 65 mm, and its form factor ratio is 0.277. In the case of a 21700 cell, its diameter is approximately 21 mm, its height is approximately 70 mm, and its form factor ratio is 0.300.

[0149] [Sixth Example] Hereinafter, a sixth embodiment of the electrode assembly according to the present invention will be described with reference to FIG.

[0150] The electrode assembly may be formed by stacking unit cells as shown in Fig. 10. In this way, a stack-type electrode assembly may be manufactured.

[0151] Here, the unit cell may be a unit cell manufactured by stacking a first electrode plate 10, a separator 30, a second electrode plate 20, and a separator 30.

[0152] These stack type electrode assemblies 1 can be used in the manufacture of secondary batteries in a form housed in a pouch (not shown).

[0153] [Seventh Example] Hereinafter, with reference to FIG. 11, a seventh embodiment of the electrode assembly according to the present invention will be described.

[0154] The electrode assembly may be fabricated by stacking a unit cell, in which a first electrode plate 10, a separator 30, and a second electrode plate 20 are sequentially stacked as shown in FIG. 1, on a folding separator 40 extending long along a folding direction as shown in FIG. 11, and folding the stacked unit cell.

[0155] The unit cells may be laminated in a manner that the first electrode plate 10 and the second electrode plate 20 are alternately placed at predetermined intervals along the longitudinal direction of the folding separator 40 .

[0156] The innermost unit cell where folding begins has an electrode plate of the same polarity as the unit cell located closest to it placed on top. A space is placed between the two adjacent unit cells. Then, by folding them one by one, a stack folding type electrode assembly 1 can be manufactured with a stacked structure as shown in Figure 10.

[0157] These stack folding type electrode assemblies 1 can be used in the manufacture of secondary batteries in a form housed in a pouch (not shown).

[0158] The above-mentioned electrode assembly structure can prevent the occurrence of a short circuit between the two electrode plates even when manufactured in various ways, as described in the embodiments, by applying an insulating coating 26 to the slit surface 237 of the current collecting part that extends wider in the width direction, among the first current collecting part 13 and the second current collecting part 23.

[0159] In addition, since the insulating coating 26 is applied before laminating the electrode plates and the separator, the manufacturing process of the electrode assembly remains almost the same.

[0160] Furthermore, these insulating coatings 26 have almost no effect on the thickness of the electrode plates, and even when the electrodes are laminated, the thickness of the portions thickened by the insulating coating does not affect the thickness of the laminated layers. Therefore, as described in the embodiments, the laminated structure of the electrode assembly can be maintained generally parallel even when manufactured using various methods.

[0161] [Manufacturing method of the second electrode plate] Hereinafter, a manufacturing process of the second electrode plate, including an insulating coating process, will be described with reference to FIGS.

[0162] The second electrode plate 20 can be prepared by coating a second active material 22 on both surfaces of a second metal foil 21, flattening the coated second active material 22 with a rolling roll or the like, and hardening the flattened second active material 22 by a method such as heating and drying, and then transferring the resultant to a slitting and insulating coating processing facility shown in FIG. 12.

[0163] Referring to FIG. 13, the second active material 22 of the second electrode plate 20 is coated on the other portions except for the second electrode tab portion 24 where the metal foil is exposed at one end, and then slit and insulating coating processes are performed.

[0164] The slitting is performed by cutting the thickness-reduced section of the coating edge of the second active material 22 at the other end of the second electrode plate 20 together with the second metal foil 21 using a slitting device 51 .

[0165] After the slitting process is performed, the other end of the second electrode plate 20 has a smooth slit surface 237 as shown in Fig. 14. Both side edges of the slit surface 237 may have a processed surface 225. The processed surface 225 may be formed during the slitting process, but may also be intentionally formed by a separate process.

[0166] These separate processes can be performed by a pinch roller 53 while the second electrode plate 20 is being transported in an upright state in order to apply an insulating coating liquid 541 to the slit surface 237 by a dipping method.

[0167] The second electrode plate 20, which has been transported by the horizontal transport rollers 52 for slitting by the slitting device 51, can be transported in an upright position so that the slit surface 237 is located at the bottom after the slitting process.

[0168] These transfers can be performed by pinch rollers 53 which support and transfer both side ends of the second electrode plate 20. Of course, although not shown in Fig. 12, in order to support the thin second electrode plate 20, transfer rollers which support both surfaces of the second electrode plate 20 can be further disposed between the pinch rollers 53 in the transfer direction.

[0169] Referring to FIG. 15, the pinch roller 53 may include a receiving surface 532 that supports the end surface of the second electrode plate 20, and an inclined central guide surface 531 that guides the end of the second electrode plate 20 to move to the center.

[0170] In the process of guiding the slit surface 237 of the second electrode plate 20 to the receiving surface 532, the corner portions of the slit surface 237 on both sides are pressed against the central guide surface 531 to form the processing surface 225.

[0171] That is, according to the present invention, since the processing surface 225 is processed by the insulating coating process performed by the dipping method, the processing surface 225 can be processed together with the second electrode plate 20 during the process of changing its posture and transferring it.

[0172] The upright second electrode plate 20 passes through the insulating coating device 54, and an insulating coating liquid 541 can be applied to the slit surface 237 at the lower part thereof.

[0173] The insulating coating device 54 is a type in which a roller brush 543 contained in an insulating coating liquid 541 viscously transports the colloidal solution-like insulating coating liquid 541, and the lower end of the second electrode plate 20 is dipped while passing through the part, and the insulating coating liquid 541 can be coated on the slit surface 237 of the second electrode plate 20.

[0174] In this manner, since the insulating coating liquid 541 applied to the slit surface 237 is subjected to gravity downward, it is possible to prevent the insulating coating liquid 541 from flowing onto both surfaces of the second electrode plate 20 and covering the surface of the second active material 22. This ensures that the insulating coating 26 is applied only to the slit surface 237 or only to a portion of the corner portion of the second active material 22 adjacent to the slit surface 237.

[0175] The insulating coating liquid 541 can be cured by a method such as heating and drying to form the insulating coating 26 layer.

[0176] The second electrode plate 20 can be supplied to a lamination process of the first electrode plate 10 and the separator 30 in a state in which the second electrode plate 20 is coated with the insulating coating 26 .

[0177] It should be understood that the above-described embodiments are illustrative in all respects and are not limiting, and the scope of the present invention is defined by the following claims rather than the above detailed description. Any modifications and variations that can be achieved within the meaning and scope of the following claims, as well as equivalent concepts, should be interpreted as being included in the scope of the present invention.

[0178] Although the present invention has been described above with reference to the illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while describing the embodiments of the present invention, it is natural that the effects that can be predicted by the configuration should also be recognized. [Explanation of symbols]

[0179] 1 Electrode assembly 10 First electrode plate (positive electrode plate) 11 First metal foil 12 First active material 13 First current collector 14 First electrode tab portion 20 Second electrode plate (negative electrode plate) 21 Second metal foil 22 Second active material 225 Machining surface 23 Second current collector 237 Slit Surface 24 Second electrode tab portion 26 Insulation Coating 30 Separation membrane 40 Folding membrane 5 Second electrode plate processing device 51 Slitting device 52 Transfer roller 53 Pinch Roller 531 Center guide surface 532 Receiving surface 54 Insulation coating equipment 541 Insulating coating liquid 542 Dipping Device 543 Roller Brush

Claims

1. The electrode assembly (1) is formed by stacking one or more first electrode plates (10), one or more separation membranes (30), and one or more second electrode plates (20). The first electrode plate (10) has a first electrode tab portion (14) on one side in the width direction of the first electrode plate (10) where the first active material (12) is not applied, The first electrode tab portion (14) extends outward in the width direction further than the separator (30) at one end of the width direction of the electrode assembly (1), At one end of the electrode assembly (1), a slit surface (237) of the second electrode plate, which is disposed adjacent to the first electrode tab portion (14) through the separation film (30), is provided with an insulating coating (26) formed separately from the separation film (30). Electrode assembly.

2. The separation membrane (30) is laminated between the first electrode plate (10) and the second electrode plate (20) with the sheet-like separation membrane (30) interposed therebetween, The insulating coating (26) is in the form of an insulating liquid that is coated and cured. The electrode assembly of claim 1 .

3. The insulating coating (26) covers the entire slit surface (237) of the second electrode plate (20) in the stacking direction of the electrode assembly (1). The electrode assembly of claim 1 .

4. The insulating coating (26) is connected to the slit surface (237) of the second electrode plate (20) and further covers a portion of the first surface of the second electrode plate (20) facing the separator (30). The electrode assembly according to claim 3 .

5. The insulating coating (26) is connected to the slit surface (237) of the second electrode plate (20) and further covers a portion of a second surface of the second electrode plate (20) facing the first surface. The electrode assembly according to claim 4 .

6. The second electrode plate (20) includes a second current collector (23) to which a second active material (22) is applied, The slit surface (237) is formed by slitting the second current collecting portion (23). The electrode assembly of claim 1 .

7. A corner portion of the second active material (22) arranged on the slit surface (237) of the second current collecting portion (23) has a processed surface (225) whose thickness is gradually reduced. The electrode assembly according to claim 6.

8. The processed surface (225) is formed by a slitting process. The electrode assembly of claim 7.

9. The processed surface (225) is formed by a pressing process after a slitting process. The electrode assembly of claim 8.

10. The insulating coating (26) is formed by spray coating. The electrode assembly of claim 1 .

11. The insulating coating (26) is formed by dipping the slit surface (237) into an insulating liquid. The electrode assembly of claim 1 .

12. The second electrode plate (20) has a second electrode tab portion (24) to which a second active material (22) is not applied, The second electrode tab portion (24) is disposed at the other end of the electrode assembly (1). The electrode assembly of claim 1 .

13. The first electrode plate (10) includes a first current collector (13) having a first active material (12) applied to both sides thereof, The second electrode plate (20) includes a second current collector (23) having a second active material (22) applied to both sides thereof, The width of the second current collecting portion (23) is greater than the width of the first current collecting portion (13). The electrode assembly of claim 1 .

14. A method for manufacturing the electrode assembly of any one of claims 1 to 13, comprising the steps of: applying a second active material (22) to both sides of a second metal foil (21) to form a second current collector (23), and slitting the other end of the second current collector (23) to form a slit surface (237); forming an insulating coating (26) on said slit surface (237); and laminating a first electrode plate (10), a separator (30), and a second electrode plate (20) having the insulating coating (26) formed thereon; A method for manufacturing an electrode assembly, comprising:

15. a step of winding up the first electrode plate (10), the separation membrane (30), and the second electrode plate (20) in a stacked state, around a winding shaft, to form a jelly roll. Further comprising: The method for manufacturing the electrode assembly according to claim 14.

16. bending the first electrode tab portion (14) exposed at the widthwise end of the electrode assembly wound in the jelly roll shape in a radial direction to form a bent surface. Further comprising: The method for manufacturing the electrode assembly according to claim 15 .

17. stacking a plurality of unit cells each including the first electrode plate (10), the separator (30), the second electrode plate (20), and the separator (30) in a stack shape; Further comprising: The method for manufacturing the electrode assembly according to claim 14.

18. placing a unit cell, in which the first electrode plate (10), the separator (30) and the second electrode plate (20) are stacked, on a plurality of folding separators to laminate them; and folding the laminated folding separator membrane into a stack folding shape; Further comprising: The method for manufacturing the electrode assembly according to claim 14.

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