Mandrel for electrode assembly, cylindrical battery cell manufactured using same, and battery pack and vehicle including same

Abstract

Disclosed are a mandrel for an electrode assembly, a cylindrical battery cell manufactured using the mandrel, and a battery pack and a vehicle including the cylindrical battery cell. A mandrel for an electrode assembly according to one embodiment of the present invention has a structure in which a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode are wound in one direction, and winds a core-wound electrode assembly having a center hole formed in the center thereof, the mandrel includes: a first winding member inserted into the center hole of the electrode assembly; and a second winding member inserted into the center hole of the electrode assembly such that the separator is interposed between the second winding member and the first winding member, and winding the electrode assembly together with the first winding member, wherein an asymmetry prevention portion may be formed on at least one of the first winding member and the second winding member to prevent asymmetry of the electrode assembly.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2022-0185086 filed on December 26, 2022, and Korean Patent Application No. 10-2023-0190498 filed on December 22, 2023 in Korea, the disclosures of which are incorporated herein by reference.

[0002] The present invention relates to a winding rod for an electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell. More specifically, the present invention relates to a winding rod for an electrode assembly capable of improving the shape asymmetry of the electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell. Background Art

[0003] Secondary batteries, which are easily applicable according to product groups and have electrical characteristics such as high energy density, are generally used in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source, and portable devices.

[0004] These secondary batteries have attracted attention as a new energy source for improving eco-friendliness and energy efficiency due to a major advantage of significantly reducing the use of fossil fuels and another advantage of not generating byproducts resulting from energy use.

[0005] Currently, widely used secondary batteries include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. The operating voltage of the unit secondary battery cell is about 2.5V to 4.5V.

[0006] Therefore, when an output voltage higher than this is required, a battery module or a battery pack is configured by connecting a plurality of battery cells in series. In addition, a battery module or a battery pack is also configured by connecting a plurality of battery cells in parallel according to a required charge / discharge capacity. Therefore, the number of battery cells included in a battery module or a battery pack and their electrical connection configurations can be set in various ways according to a required output voltage or charge / discharge capacity.

[0007] Cylindrical, prismatic and pouch-type battery cells are known as types of secondary battery cells. In the case of a cylindrical battery cell, an insulating separator is inserted between a positive electrode plate and a negative electrode plate, and is wound using a winding rod to form a jellyroll-type electrode assembly, which is inserted into a battery can together with an electrolyte to constitute a battery. In addition, a cylindrical battery cell may be provided with a current collector to electrically connect the positive electrode plate and the negative electrode plate, respectively.

[0008] Here, a winding rod for winding a jellyroll-type electrode assembly has a rod shape having a substantially circular cross section, is inserted into a central hole of the electrode assembly, and is rotated while sandwiching a separator to wind the electrode assembly.

[0009] However, when the electrode assembly is wound using a conventional winding rod, there is a problem of an increased asymmetric difference between the maximum outer diameter of the electrode assembly and the minimum outer diameter of the electrode assembly. A large asymmetric difference indicates that the electrode assembly has an asymmetric shape, and if the asymmetric difference increases, the outer diameter of the entire electrode assembly increases and the capacity decreases. In addition, the shrinkage and expansion of the electrode assembly having an asymmetric shape causes a problem of cracks in the electrode.

[0010] Furthermore, when the conventional winding rod contacts and clamps the separator, sliding occurs therebetween, causing defects in winding the electrode assembly and thereby worsening the asymmetry of the electrode assembly. Summary of the invention

[0011] Technical issues

[0012] The present invention aims to solve the problems of the prior art, and therefore the present invention aims to provide a winding rod for an electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell, wherein the winding rod is capable of improving the shape asymmetry of the electrode assembly by optimizing the asymmetric difference of the electrode assembly.

[0013] In addition, the present invention provides a winding rod for an electrode assembly capable of increasing capacity by improving shape asymmetry of an electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell.

[0014] Furthermore, the present invention provides a winding rod for an electrode assembly capable of preventing cracks in an electrode caused by an asymmetric shape of an electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell.

[0015] In addition, the present invention provides a winding rod for an electrode assembly, which can prevent a separator from sliding when clamping the separator, thereby preventing the asymmetry of the electrode assembly from deteriorating, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell.

[0016] However, the technical problems that the present disclosure seeks to solve are not limited to the above-mentioned problems, and other problems not mentioned above will be clearly understood by those skilled in the art from the description of the present invention described below.

[0017] Technical Solution

[0018] According to one aspect of the present disclosure, a winding rod for an electrode assembly is provided, the winding rod being wound around a core-type electrode assembly, the electrode assembly having a structure in which a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode are wound in one direction, and the electrode assembly has a central hole formed in the center, the winding rod comprising: a first winding member, the first winding member being inserted into the central hole of the electrode assembly; and a second winding member, the second winding member being inserted into the central hole of the electrode assembly so that the separator is interposed between the first winding member and the second winding member, and the second winding member being configured to wind the electrode assembly together with the first winding member, and an asymmetry preventing portion may be formed on at least one of the first winding member and the second winding member to prevent asymmetry of the electrode assembly.

[0019] In one embodiment, the area of ​​the first winding member may be different from the area of ​​the second winding member.

[0020] In one embodiment, a cross section of the first winding member may include: a first curved portion formed as a curve; and a first straight portion configured to connect both ends of the first curved portion.

[0021] In one embodiment, the asymmetric preventing portion may include a first rounded portion formed on both ends where the first curved portion and the first straight portion meet.

[0022] In one embodiment, the asymmetric preventing portion may include a first chamfered portion formed on both ends where the first curved portion and the first straight portion meet.

[0023] In one embodiment, the asymmetric preventing portion may include a first wavy pattern portion formed on both ends where the first curved portion and the first straight portion meet.

[0024] In one embodiment, a cross section of the second winding member may include: a second curved portion formed as a curve; and a second straight portion configured to connect both ends of the second curved portion.

[0025] In one embodiment, the asymmetric preventing portion may include a second rounded portion formed on both ends where the second curved portion and the second straight portion meet.

[0026] In one embodiment, the asymmetric preventing portion may include a second chamfered portion formed on both ends where the second curved portion and the second straight portion meet.

[0027] In one embodiment, the asymmetric preventing portion may include a second wavy pattern portion formed on both ends where the second curved portion and the second straight portion meet.

[0028] In one embodiment, the first rounded portion may have a curvature radius of 0.4 mm to 0.8 mm.

[0029] In one embodiment, the second rounded portion may have a curvature radius of 0.4 mm to 0.8 mm.

[0030] In one embodiment, the first straight line portion may include a first fine protrusion formed throughout the first straight line portion to prevent the diaphragm from sliding.

[0031] In one embodiment, the second straight line portion may include a second fine protrusion formed throughout the second straight line portion to prevent the diaphragm from sliding.

[0032] Furthermore, according to another aspect of the present disclosure, a cylindrical battery cell manufactured using the above-mentioned winding rod for an electrode assembly may be provided, a battery pack including at least one above-mentioned cylindrical battery cell may be provided, and a vehicle including at least one above-mentioned cylindrical battery cell may be provided.

[0033] Beneficial Effects

[0034] The embodiments of the present disclosure have the effect of improving the shape asymmetry of the electrode assembly by optimizing the asymmetric difference of the electrode assembly.

[0035] Furthermore, the embodiments of the present disclosure have the effect of increasing capacity by improving the shape asymmetry of the electrode assembly.

[0036] Furthermore, the embodiments of the present disclosure have the effect of preventing cracks in the electrode that may be caused by the asymmetric shape of the electrode assembly.

[0037] Furthermore, the embodiments of the present disclosure have the effect of preventing the separator from sliding when the separator is clamped, thereby preventing the asymmetry of the electrode assembly from being deteriorated.

[0038] However, effects obtainable from the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned above will be clearly understood by those skilled in the art from the explanation of the present invention described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present invention, are used to provide further understanding of the technical idea of ​​the present disclosure; therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0040] Figure 1 is a schematic diagram illustrating a state in which a winding rod for an electrode assembly according to an embodiment of the present disclosure is coupled to an electrode assembly.

[0041] Figure 2 is a schematic cross-sectional view of a winding rod for an electrode assembly according to an embodiment of the present disclosure.

[0042] Figure 3 is a cross-sectional view of a winding rod for an electrode assembly according to a modified embodiment of the present disclosure.

[0043] Figure 4 is a cross-sectional view of a winding rod for an electrode assembly according to another modified embodiment of the present disclosure.

[0044] FIGS. 5 to 25 illustrate experimental data of asymmetric differences in rounded portions having different radii of curvature in a winding rod for an electrode assembly according to an embodiment of the present disclosure.

[0045] Fig.26 The average values ​​of the asymmetry differences according to the experimental data in FIGS. 5 to 25 are shown.

[0046] Fig. 27 Shown according to Fig.26 A graph of the mean values ​​of the asymmetry differences in the .

[0047] Fig.28 is a schematic cross-sectional view of a winding rod for an electrode assembly according to another embodiment of the present disclosure.

[0048] Fig.29 is a diagram schematically illustrating a configuration of a battery pack including a cylindrical battery cell manufactured using a winding rod for an electrode assembly according to various embodiments of the present disclosure.

[0049] Fig.30 It is shown that Fig.29 Diagram of a battery pack in a vehicle. DETAILED DESCRIPTION

[0050] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but are interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms for the best interpretation. Therefore, the configurations proposed in the embodiments and drawings of this specification only indicate the best embodiments of the present disclosure, and do not represent all the technical ideas of the present disclosure, so it should be understood that various equivalents and modifications may be made to them when submitting this application.

[0051] The sizes of the various elements or specific parts of each element shown in the drawings are exaggerated, omitted or simplified for the convenience of explanation and illustration. Therefore, the sizes of the various elements do not fully reflect their actual sizes. The description of the related known functions or configurations that may obscure the subject matter of the present disclosure will be omitted.

[0052] The term “coupled” or “connected” used in this specification refers to a case where one member is indirectly coupled or connected to another member through a connecting member, as well as a case where one member is directly coupled or connected to another member.

[0053] Figure 1 is a schematic diagram showing a state in which a winding rod for an electrode assembly according to an embodiment of the present disclosure is coupled to an electrode assembly, and Figure 2 is a schematic cross-sectional view of a winding rod for an electrode assembly according to an embodiment of the present disclosure.

[0054] Reference Figure 1 and Figure 2 The winding rod 10 for an electrode assembly according to an embodiment of the present disclosure is used to wind a core-wound electrode assembly 21 (see FIG. 2 ) during the manufacturing process of a cylindrical battery cell 20. Fig.29 ). The electrode assembly 21 may be a winding core type having a structure in which a positive electrode (or a positive electrode plate), a negative electrode (or a negative electrode plate), and a separator 23 interposed between the positive electrode and the negative electrode are wound in one direction, and a central hole 22 is formed at the center. Then, a winding rod 10 for an electrode assembly is inserted into the central hole 22 of the electrode assembly 21 to wind the electrode assembly 21. Figure 2 Only a portion of the diaphragm 23 is shown.

[0055] Here, the cylindrical battery cell 20 may include an electrode assembly 21 , a battery can, and a cap plate.

[0056] The electrode assembly 21 has a structure in which a positive plate, a negative plate, and a separator 23 interposed therebetween are wound in one direction. In addition, a center hole 22 may be formed at the center of the electrode assembly 21, and it may be formed in a core-wound type.

[0057] For example, the electrode assembly 21 may be manufactured by winding at least once a laminate formed by sequentially stacking a negative electrode plate, a separator 23, a positive electrode plate, and a separator 23. Here, the positive electrode plate and the negative electrode plate may be formed in a sheet shape.

[0058] That is, the electrode assembly 21 applied to the present embodiment may be a wound type electrode assembly 21. In this case, an additional separator 23 may be provided on the outer surface of the electrode assembly 21 for insulation from the battery can. That is, the electrode assembly 21 may have a winding structure known in the prior art without limitation.

[0059] The positive electrode active material may be applied to one or both sides of the positive electrode plate, and a first uncoated portion to which the positive electrode active material is not applied may be formed at the end of the positive electrode plate. The first uncoated portion may be formed around the center of the electrode assembly 21 to be exposed to the outside of the separator 23, and may serve as an electrode tab. However, the first uncoated region may not be formed on the positive electrode plate.

[0060] The negative electrode active material may be applied to one or both sides of the negative electrode plate, and a second uncoated region to which the negative electrode active material is not applied may be formed at the end of the negative electrode plate. The second uncoated portion may be formed around the center of the electrode assembly 21 to be exposed to the outside of the separator 23, and may be used as an electrode tab. However, the second uncoated region may not be formed on the negative electrode plate.

[0061] Here, when the first uncoated region and the second uncoated region are formed, the first uncoated region and the second uncoated region may be configured to face opposite directions to each other.

[0062] Furthermore, any active material known in the art may be used for the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode plate.

[0063] The separator 23 may be configured as a porous polymer film made of a polyolefin polymer (eg, ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer, etc.) alone or as a stack thereof.

[0064] As another example, the separator 23 may be configured as a typical porous non-woven fabric, such as a non-woven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, or the like.

[0065] The separator 23 may include a coating of inorganic particles on at least one surface thereof. The separator 23 itself may also be made of a coating of inorganic particles. The particles constituting the coating may have a structure combined with a binder so that there is a gap volume between adjacent particles.

[0066] In addition, the central hole 22 of the electrode assembly 21 is also used to weld the cell terminal (positive terminal) and the positive current collector plate. That is, the cell terminal and the positive current collector plate can be welded by irradiating laser through the central hole 22 of the electrode assembly 21.

[0067] The electrode assembly 21 is stored in the battery can. In addition, the battery can may have a through hole formed thereon. Here, the battery can may be formed in a cylindrical shape so that the electrode assembly 21 is stored in the battery can and it may be electrically connected to the negative electrode plate of the electrode assembly 21. Therefore, the battery can may have the same polarity as the negative electrode plate (ie, negative electrode).

[0068] The diameter of the battery can is configured to be greater than the diameter of the electrode assembly 21. A gap of a predetermined size may be formed between the battery can and the positive electrode collector plate, and an insulator may be disposed in the gap.

[0069] If the size of the electrode assembly 21 is increased in a battery can having a certain size according to the standard, the total capacity of the battery cell 20 increases, but a gap between the battery can and the electrode assembly 21 decreases.

[0070] That is, if the size of the electrode assembly 21 is increased to increase the total capacity of the battery cell 20, the gap between the battery can and the electrode assembly 21 is reduced, and thus the increase in the capacity of the battery cell 20 requires an insulator to be provided in the reduced gap between the battery can and the electrode assembly 21, and to this end, it is desired that the insulator be as thin as possible.

[0071] In addition, if the shape asymmetry of the electrode assembly 21 is improved by optimizing the asymmetric difference of the electrode assembly 21 through the winding rod 10 for the electrode assembly according to an embodiment of the present disclosure, more positive and negative electrodes can be arranged in the same space (e.g., a battery can), thereby increasing the total capacity.

[0072] The battery can is a substantially cylindrical container and may be made of a conductive material such as metal. Although the battery can may be made of a conductive metal (eg, aluminum, steel, or stainless steel), it is not limited thereto.

[0073] The positive current collector plate is electrically connected to the positive electrode plate, for example, at the top of the electrode assembly 21. For example, the positive current collector plate may be made of a conductive metal material and electrically connected to the first uncoated portion of the positive electrode plate.

[0074] The cell terminal is made of a conductive metal material and is electrically connected to the positive electrode collector plate. In addition, the cell terminal is electrically connected to the positive electrode plate of the electrode assembly 21 through the positive electrode collector plate, thereby having a positive polarity.

[0075] That is, the cell terminal may be used as a positive terminal. In addition, as described above, the battery can may be electrically connected to the negative electrode plate of the electrode assembly 21 to have a negative polarity.

[0076] The negative current collector plate is electrically connected to the negative electrode plate, for example, at the bottom of the electrode assembly 21. For example, the negative current collector plate may be made of a conductive metal material such as aluminum, steel, copper or nickel, and is electrically connected to the second uncoated portion of the negative electrode plate.

[0077] The negative electrode collector plate may be electrically connected to the battery can. To this end, at least a portion of an edge of the negative electrode collector plate may be interposed between an inner surface of the battery can and a sealing gasket and fixed thereto.

[0078] As an example, at least a portion of the edge of the negative electrode current collector plate may be fixed to the beaded portion by welding while being supported on the bottom surface of the beaded portion formed at the bottom of the battery can.

[0079] In addition, at least a portion of the remaining portion excluding the connection portion of the edge pressing portion of the negative electrode collector plate may be connected to the curved surface of the second non-coating portion by welding (eg, laser welding).

[0080] In addition, at least a portion of an edge of the negative electrode collector plate may be electrically coupled to one of an upper surface and a lower surface of the crimping portion near the curling portion.

[0081] The cover plate is configured to seal an opening formed at the bottom of the battery can. The cover plate may be made of, for example, a metal material to ensure rigidity.

[0082] In addition, the cap plate may be separated from the electrode assembly 21 and may be provided without polarity. That is, even if the cap plate is made of a conductive metal material, the cap plate may not have polarity.

[0083] The fact that the cover plate has no polarity indicates that the cover plate is electrically insulated from the battery can and the cell terminals. As mentioned above, the cover plate does not need to have polarity, and its material does not necessarily have to be a conductive metal.

[0084] The cover plate may be located on and supported by a crimping portion formed on the battery can. In addition, the cover plate is fixed by a curling portion described later. A sealing gasket ring may be interposed between the cover plate and the curling portion of the battery can to ensure airtightness of the battery can. That is, the sealing gasket may be configured to be interposed between the edge of the cover plate and the opening of the battery can.

[0085] The winding rod 10 for an electrode assembly according to an embodiment of the present disclosure may be applied to various types of cylindrical battery cells 20. For example, the winding rod 10 may be applied to a jointless cylindrical battery cell 20 in which the first uncoated portion of the positive electrode plate or the second uncoated portion of the negative electrode plate is an electrode joint without a separate electrode joint, and to a battery cell 20 in which a separate electrode joint is coupled to the positive electrode plate or the negative electrode plate.

[0086] Reference Figure 1 and Figure 2 , a winding rod 10 for an electrode assembly according to an embodiment of the present disclosure includes a first winding member 100 and a second winding member 200 .

[0087] The first wound member 100 is inserted into the central hole 22 of the electrode assembly 21 .

[0088] The first winding member 100 may be formed in various shapes. Figure 2 , the first winding member 100 may have a cross section configured to include a first curved portion 110 and a first straight portion 120. The first curved portion 110 is formed as a curve. The first curved portion 110 may be changed, but may be formed in the shape of a part of a circle, that is, an arc. The first straight portion 120 may be configured to connect both ends of the first curved portion 110.

[0089] Therefore, the first winding member 100 may be configured similar to, for example Figure 2 The semicircular shape shown.

[0090] In addition, the second winding member 200 is inserted into the central hole 22 of the electrode assembly 21 so that the separator 23 is inserted between the first winding member 100 and the second winding member 200, and the electrode assembly 21 is wound together with the first winding member 100. That is, the first winding member 100 and the second winding member 200 rotate while sandwiching the separator 23 so that the first winding member 100 is in contact with one side of the separator 23 and the second winding member 200 is in contact with the other side of the separator 23, thereby winding the electrode assembly 21.

[0091] The second winding member 200 may be formed in various shapes. Figure 2 , the second winding member 200 may have a cross section configured to include a second curved portion 210 and a second straight portion 220. The second curved portion 210 is formed as a curve. The second curved portion 210 may be changed, but may be formed in the shape of a part of a circle, that is, an arc. The second straight portion 220 may be configured to connect both ends of the second curved portion 210.

[0092] Therefore, the second winding member 200 may be formed similar to, for example Figure 2 The semicircular shape shown.

[0093] Here, if Figure 2 As shown, the area of ​​the first winding member 100 and the area of ​​the second winding member 200 may be configured to be different from each other. The first winding member 100 and the second winding member 200 rotate in one direction of the clockwise direction or the counterclockwise direction, and in this case, one of the first winding member 100 and the second winding member 200 may apply a greater force.

[0094] Therefore, in addition to the asymmetry preventing portion 130 or 230 described below, one of the first winding member 100 and the second winding member 200 to which a greater force is applied when rotating may also have a larger area than the other to ensure balance when the electrode assembly 21 is wound by the winding members, thereby obtaining an effect of further improving the shape asymmetry of the electrode assembly 21 caused by the area difference between the first winding member 100 and the second winding member 200.

[0095] The asymmetry preventing portion 130 or 230 may be formed on at least one of the first wound member 100 and the second wound member 200 to prevent asymmetry of the electrode assembly 21. That is, the asymmetry preventing portion 130 or 230 may be formed only on the first wound member 100, may be formed only on the second wound member 200, or may be formed on both the first wound member 100 and the second wound member 200.

[0096] The asymmetric preventing portion 130 or 230 may vary and include, for example, a rounded portion 131 or 231 , a chamfered portion 132 or 232 , and a wave pattern portion 133 or 233 .

[0097] Reference Figure 2 The asymmetric preventing portion 130 or 230 may include a rounded portion 131 or 231 , for example, the first rounded portion 131 may be formed on the first winding member 100 , and the second rounded portion 231 may be formed on the second winding member 200 .

[0098] The first rounded portions 131 are formed at both ends where the first curved portion 110 and the first straight portion 120 intersect. In addition, the second rounded portions 231 are formed at both ends where the second curved portion 210 and the second straight portion 220 intersect.

[0099] Here, if the first rounded portion 131 is formed on the first winding member 100 and if the second rounded portion 231 is formed on the second winding member 200 , there is an effect of preventing the diaphragm 23 from being damaged when the diaphragm 23 is inserted between the first and second winding members 100 and 200 .

[0100] In addition, if the first rounded portion 131 is formed on the first winding member 100, and if the second rounded portion 231 is formed on the second winding member 200, when the electrode assembly 21 is wound by the rotation of the first winding member 100 and the winding member 200, the shape asymmetry of the electrode assembly 21 can be improved. A detailed description thereof will be provided later with reference to experimental data.

[0101] Figure 3is a cross-sectional view of a winding rod for an electrode assembly according to a modified embodiment of the present disclosure.

[0102] Reference Figure 3 , the asymmetric preventing portion 130 or 230 may include a chamfered portion 132 or 232. Here, the first chamfered portion 132 is formed at both ends where the first curved portion 110 and the first straight portion 120 intersect, and the second chamfered portion 232 is formed at both ends where the second curved portion 210 and the second straight portion 220 intersect.

[0103] As described above, if the chamfered portions 132 and 232 are formed on the first and second wound members 100 and 200 , like the rounded portions 131 and 231 formed thereon, there is an effect of improving the shape asymmetry of the electrode assembly 21 .

[0104] In addition, the description of the aforementioned embodiment related to the rounded portions 131 and 231 can also be applied to Figure 3 The configuration of the modified embodiment is Figure 3 The configuration of the modified embodiment is the same as in.

[0105] Figure 4 is a cross-sectional view of a winding rod for an electrode assembly according to another modified embodiment of the present disclosure.

[0106] Reference Figure 4 The asymmetric preventing portion 130 or 230 may include a wave pattern portion 133 or 233. Here, the first wave pattern portion 133 is formed at both ends where the first curved portion 110 and the first straight portion 120 intersect, and the second wave pattern portion 233 is formed at both ends where the second curved portion 210 and the second straight portion 220 intersect.

[0107] As described above, if the wave pattern portions 133 and 233 are formed on the first and second wound members 100 and 200 like the rounded portions 131 and 231 formed thereon, there is an effect of improving the shape asymmetry of the electrode assembly 21 .

[0108] In addition, the description of the aforementioned embodiment related to the rounded portions 131 and 231 can also be applied to Figure 3 The configuration of the modified embodiment is Figure 3 The configuration of the modified embodiment is the same as in.

[0109] FIGS. 5 to 25 show experimental data of asymmetric differences in rounded portions having different radii of curvature in a winding rod for an electrode assembly according to an embodiment of the present disclosure, Fig.26shows the average value of the asymmetry difference according to the experimental data in FIGS. 5 to 25 , and Fig. 27 Shown according to Fig.26 A graph of the mean values ​​of the asymmetry differences in . Fig.26 In the formula, R is the radius of curvature. For example, R0.2 indicates that the radius of curvature is 0.2 mm. Fig.26 In , the mean represents the average of the asymmetry differences.

[0110] The experiments in FIGS. 5 to 25 were conducted under the same conditions, wherein the thickness of the positive electrode was 162 μm, the thickness of the negative electrode was 195 μm, and the thickness of the separator 1 and the separator 2 were 13 μm, respectively. In addition, while changing the radius of curvature of the first rounded portion 131 of the first wound member 100 and the radius of curvature of the second rounded portion 231 of the second wound member, the outer diameter of the electrode assembly 21 was measured for each radius of curvature in multiple directions, thereby deriving the asymmetric difference. The units of the outer diameter and the asymmetric difference are mm.

[0111] Here, the asymmetric difference refers to the difference between the maximum outer diameter of the electrode assembly 21 and the minimum outer diameter of the electrode assembly 21, and as the difference between the maximum outer diameter of the electrode assembly 21 and the minimum outer diameter of the electrode assembly 21 (i.e., the asymmetric difference) decreases, its shape becomes closer to a circle, thereby increasing the symmetry.

[0112] In this experiment, the curvature radii were 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, and 0.8 mm, respectively, and the average value obtained from three experiments for each curvature radius was taken as the final value (see Fig.26 ). In addition, based on Fig.26 The results obtained in Fig. 27 The curve graph in .

[0113] 5 to 7 relate to a case where the curvature radius of the first rounded portion 131 of the first wound member 100 is 0.2 mm and the curvature radius of the second rounded portion 231 of the second wound member 200 is 0.2 mm, and the electrode assembly 21 is wound by the first and second wound members 100 and 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions, thereby obtaining an asymmetric difference.

[0114] The directions in which the outer diameter of the electrode assembly 21 is measured are the 0 degree direction, the 45 degree direction, the 90 degree direction, the 135 degree direction, the 180 degree direction, the 225 degree direction, the 270 degree direction, and the 315 degree direction, and the difference between the maximum and minimum values ​​in the above values ​​corresponds to the asymmetry difference. Figure 8 to Figure 2 The same applies to 5.

[0115] Reference Figure 5aIn the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.2 mm, an outer diameter in the 0 degree direction is 44.881, an outer diameter in the 45 degree direction is 44.634, an outer diameter in the 90 degree direction is 44.498, an outer diameter in the 135 degree direction is 44.374, an outer diameter in the 180 degree direction is 44.881, an outer diameter in the 225 degree direction is 44.634, an outer diameter in the 270 degree direction is 44.498, and an outer diameter in the 315 degree direction is 44.374. Among them, the difference between the maximum outer diameter 44.881 and the minimum outer diameter 44.374 is about 0.51. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.2 mm, the asymmetry difference is about 0.51.

[0116] In addition, refer to Figure 5b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 5b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0117] Reference Figure 6a In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.2 mm, an outer diameter in the 0 degree direction is 44.839, an outer diameter in the 45 degree direction is 44.607, an outer diameter in the 90 degree direction is 44.479, an outer diameter in the 135 degree direction is 44.359, an outer diameter in the 180 degree direction is 44.839, an outer diameter in the 225 degree direction is 44.607, an outer diameter in the 270 degree direction is 44.479, and an outer diameter in the 315 degree direction is 44.359. Among them, the difference between the maximum outer diameter 44.839 and the minimum outer diameter 44.359 is 0.48. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.2 mm, the asymmetry difference is 0.48.

[0118] In addition, refer to Figure 6b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 6b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0119] Reference Figure 7aIn the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.2 mm, an outer diameter in the 0 degree direction is 44.725, an outer diameter in the 45 degree direction is 44.591, an outer diameter in the 90 degree direction is 44.384, an outer diameter in the 135 degree direction is 44.404, an outer diameter in the 180 degree direction is 44.725, an outer diameter in the 225 degree direction is 44.591, an outer diameter in the 270 degree direction is 44.384, and an outer diameter in the 315 degree direction is 44.404. Among them, the difference between the maximum outer diameter 44.725 and the minimum outer diameter 44.384 is about 0.34. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.2 mm, the asymmetry difference is about 0.34.

[0120] In addition, refer to Figure 7b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 7b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0121] Figures 8 to 10 A case where the curvature radius of the first rounded portion 131 of the first wound member 100 is 0.3 mm and the curvature radius of the second rounded portion 231 of the second wound member 200 is 0.3 mm is involved, and the electrode assembly 21 is wound by the first wound member 100 and the second wound member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions, thereby obtaining an asymmetric difference.

[0122] Reference Figure 8 In the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.3 mm, an outer diameter in the 0 degree direction is 44.830, an outer diameter in the 45 degree direction is 44.420, an outer diameter in the 90 degree direction is 44.556, an outer diameter in the 135 degree direction is 44.469, an outer diameter in the 180 degree direction is 44.830, an outer diameter in the 225 degree direction is 44.420, an outer diameter in the 270 degree direction is 44.556, and an outer diameter in the 315 degree direction is 44.469. Among them, the difference between the maximum outer diameter 44.830 and the minimum outer diameter 44.420 is 0.41. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.3 mm, the asymmetry difference is 0.41.

[0123] Reference Fig. 9In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.3 mm, an outer diameter in the 0 degree direction is 44.873, an outer diameter in the 45 degree direction is 44.592, an outer diameter in the 90 degree direction is 44.499, an outer diameter in the 135 degree direction is 44.560, an outer diameter in the 180 degree direction is 44.873, an outer diameter in the 225 degree direction is 44.592, an outer diameter in the 270 degree direction is 44.499, and an outer diameter in the 315 degree direction is 44.560. Among them, the difference between the maximum outer diameter 44.873 and the minimum outer diameter 44.499 is about 0.37. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.3 mm, the asymmetry difference is 0.37.

[0124] Reference Fig.10 In the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.3 mm, an outer diameter in the 0 degree direction is 44.795, an outer diameter in the 45 degree direction is 44.610, an outer diameter in the 90 degree direction is 44.485, an outer diameter in the 135 degree direction is 44.345, an outer diameter in the 180 degree direction is 44.795, an outer diameter in the 225 degree direction is 44.610, an outer diameter in the 270 degree direction is 44.485, and an outer diameter in the 315 degree direction is 44.345. Among them, the difference between the maximum outer diameter 44.795 and the minimum outer diameter 44.345 is 0.45. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.3 mm, the asymmetry difference is 0.45.

[0125] Figures 11 to 13 A case where the curvature radius of the first rounded portion 131 of the first wound member 100 is 0.4 mm and the curvature radius of the second rounded portion 231 of the second wound member 200 is 0.4 mm is involved, and the electrode assembly 21 is wound by the first wound member 100 and the second wound member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions, thereby obtaining an asymmetric difference.

[0126] Reference Fig.11In the first experiment, the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.4 mm, the outer diameter in the 0 degree direction is 44.794, the outer diameter in the 45 degree direction is 44.556, the outer diameter in the 90 degree direction is 44.526, the outer diameter in the 135 degree direction is 44.497, the outer diameter in the 180 degree direction is 44.794, the outer diameter in the 225 degree direction is 44.556, the outer diameter in the 270 degree direction is 44.526, and the outer diameter in the 315 degree direction is 44.497. Among them, the difference between the maximum outer diameter 44.794 and the minimum outer diameter 44.497 is about 0.30. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.4 mm, the asymmetry difference is about 0.30.

[0127] Reference Fig.12 In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.4 mm, an outer diameter in the 0 degree direction is 44.795, an outer diameter in the 45 degree direction is 44.624, an outer diameter in the 90 degree direction is 44.485, an outer diameter in the 135 degree direction is 44.497, an outer diameter in the 180 degree direction is 44.795, an outer diameter in the 225 degree direction is 44.624, an outer diameter in the 270 degree direction is 44.485, and an outer diameter in the 315 degree direction is 44.497. Among them, the difference between the maximum outer diameter 44.795 and the minimum outer diameter 44.485 is 0.31. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.4 mm, the asymmetry difference is 0.31.

[0128] Reference Fig.13 In the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.4 mm, an outer diameter in the 0 degree direction is 44.847, an outer diameter in the 45 degree direction is 44.557, an outer diameter in the 90 degree direction is 44.465, an outer diameter in the 135 degree direction is 44.575, an outer diameter in the 180 degree direction is 44.847, an outer diameter in the 225 degree direction is 44.557, an outer diameter in the 270 degree direction is 44.465, and an outer diameter in the 315 degree direction is 44.575. Among them, the difference between the maximum outer diameter 44.847 and the minimum outer diameter 44.465 is about 0.38. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.4 mm, the asymmetry difference is about 0.38.

[0129] Figures 14 to 16A case where the curvature radius of the first rounded portion 131 of the first wound member 100 is 0.5 mm and the curvature radius of the second rounded portion 231 of the second wound member 200 is 0.5 mm is involved, and the electrode assembly 21 is wound by the first wound member 100 and the second wound member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions, thereby obtaining an asymmetric difference.

[0130] Reference Fig.14 In the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.5 mm, an outer diameter in the 0 degree direction is 44.780, an outer diameter in the 45 degree direction is 44.556, an outer diameter in the 90 degree direction is 44.422, an outer diameter in the 135 degree direction is 44.469, an outer diameter in the 180 degree direction is 44.780, an outer diameter in the 225 degree direction is 44.556, an outer diameter in the 270 degree direction is 44.422, and an outer diameter in the 315 degree direction is 44.469. Among them, the difference between the maximum outer diameter 44.780 and the minimum outer diameter 44.422 is about 0.36. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.5 mm, the asymmetry difference is about 0.36.

[0131] Reference Fig.15 In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.5 mm, an outer diameter in the 0 degree direction is 44.773, an outer diameter in the 45 degree direction is 44.573, an outer diameter in the 90 degree direction is 44.494, an outer diameter in the 135 degree direction is 44.552, an outer diameter in the 180 degree direction is 44.773, an outer diameter in the 225 degree direction is 44.573, an outer diameter in the 270 degree direction is 44.494, and an outer diameter in the 315 degree direction is 44.552. Among them, the difference between the maximum outer diameter 44.773 and the minimum outer diameter 44.494 is about 0.28. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.5 mm, the asymmetry difference is about 0.28.

[0132] Reference Fig.16In the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.5 mm, an outer diameter in the 0 degree direction is 44.755, an outer diameter in the 45 degree direction is 44.648, an outer diameter in the 90 degree direction is 44.486, an outer diameter in the 135 degree direction is 44.575, an outer diameter in the 180 degree direction is 44.755, an outer diameter in the 225 degree direction is 44.648, an outer diameter in the 270 degree direction is 44.486, and an outer diameter in the 315 degree direction is 44.575. Among them, the difference between the maximum outer diameter 44.755 and the minimum outer diameter 44.486 is about 0.27. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.5 mm, the asymmetry difference is about 0.27.

[0133] 17 to 19 relate to a case where the radius of curvature of the first rounded portion 131 of the first winding member 100 is 0.6 mm and the radius of curvature of the second rounded portion 231 of the second winding member 200 is 0.6 mm, and the electrode assembly 21 is wound by the first winding member 100 and the second winding member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions to obtain an asymmetric difference.

[0134] Reference Fig.17a In the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.6 mm, an outer diameter in the 0 degree direction is 44.484, an outer diameter in the 45 degree direction is 44.32, an outer diameter in the 90 degree direction is 44.287, an outer diameter in the 135 degree direction is 44.484, an outer diameter in the 180 degree direction is 44.484, an outer diameter in the 225 degree direction is 44.32, an outer diameter in the 270 degree direction is 44.287, and an outer diameter in the 315 degree direction is 44.484. Among them, the difference between the maximum outer diameter 44.484 and the minimum outer diameter 44.287 is about 0.2. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.6 mm, the asymmetry difference is about 0.2.

[0135] In addition, refer to Fig.17b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Fig.17b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0136] Reference Fig.18aIn the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.6 mm, an outer diameter in the 0 degree direction is 44.479, an outer diameter in the 45 degree direction is 44.339, an outer diameter in the 90 degree direction is 44.494, an outer diameter in the 135 degree direction is 44.439, an outer diameter in the 180 degree direction is 44.479, an outer diameter in the 225 degree direction is 44.339, an outer diameter in the 270 degree direction is 44.494, and an outer diameter in the 315 degree direction is 44.439. Among them, the difference between the maximum outer diameter 44.494 and the minimum outer diameter 44.339 is about 0.16. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.6 mm, the asymmetry difference is about 0.16.

[0137] In addition, refer to Fig.18b In the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200, the outer diameter of the electrode assembly 21 is not maximized. Fig.18b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0138] Reference Fig.19a In the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.6 mm, an outer diameter in the 0 degree direction is 44.524, an outer diameter in the 45 degree direction is 44.292, an outer diameter in the 90 degree direction is 44.546, an outer diameter in the 135 degree direction is 44.516, an outer diameter in the 180 degree direction is 44.524, an outer diameter in the 225 degree direction is 44.292, an outer diameter in the 270 degree direction is 44.546, and an outer diameter in the 315 degree direction is 44.516. Among them, the difference between the maximum outer diameter 44.546 and the minimum outer diameter 44.292 is about 0.25. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.6 mm, the asymmetry difference is about 0.25.

[0139] In addition, refer to Fig.19b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Fig.19b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0140] 20 to 22 relate to a case where the radius of curvature of the first rounded portion 131 of the first winding member 100 is 0.7 mm, and the radius of curvature of the second rounded portion 231 of the second winding member 200 is 0.7 mm, and the electrode assembly 21 is wound by the first winding member 100 and the second winding member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions to obtain an asymmetric difference.

[0141] Reference Fig.20a In the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.7 mm, an outer diameter in the 0 degree direction is 44.582, an outer diameter in the 45 degree direction is 44.779, an outer diameter in the 90 degree direction is 44.499, an outer diameter in the 135 degree direction is 44.542, an outer diameter in the 180 degree direction is 44.582, an outer diameter in the 225 degree direction is 44.779, an outer diameter in the 270 degree direction is 44.499, and an outer diameter in the 315 degree direction is 44.542. Among them, the difference between the maximum outer diameter 44.779 and the minimum outer diameter 44.499 is 0.28. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.7 mm, the asymmetry difference is 0.28.

[0142] In addition, refer to Fig.20b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Fig.20b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0143] Reference Fig.21a In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.7 mm, an outer diameter in the 0 degree direction is 44.740, an outer diameter in the 45 degree direction is 44.715, an outer diameter in the 90 degree direction is 44.791, an outer diameter in the 135 degree direction is 44.881, an outer diameter in the 180 degree direction is 44.740, an outer diameter in the 225 degree direction is 44.715, an outer diameter in the 270 degree direction is 44.791, and an outer diameter in the 315 degree direction is 44.881. Among them, the difference between the maximum outer diameter 44.881 and the minimum outer diameter 44.715 is about 0.17. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.7 mm, the asymmetry difference is about 0.17.

[0144] In addition, refer to Figure 21bIt can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 21b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0145] Reference Fig.22a In the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.7 mm, an outer diameter in the 0 degree direction is 44.562, an outer diameter in the 45 degree direction is 44.660, an outer diameter in the 90 degree direction is 44.666, an outer diameter in the 135 degree direction is 44.494, an outer diameter in the 180 degree direction is 44.562, an outer diameter in the 225 degree direction is 44.660, an outer diameter in the 270 degree direction is 44.666, and an outer diameter in the 315 degree direction is 44.494. Among them, the difference between the maximum outer diameter 44.666 and the minimum outer diameter 44.494 is about 0.17. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.7 mm, the asymmetry difference is about 0.17.

[0146] In addition, refer to Figure 22b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 22b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0147] 23 to 25 relate to a case where the radius of curvature of the first rounded portion 131 of the first winding member 100 is 0.8 mm, and the radius of curvature of the second rounded portion 231 of the second winding member 200 is 0.8 mm, and the electrode assembly 21 is wound by the first winding member 100 and the second winding member 200, and then the outer diameter of the electrode assembly 21 is measured in multiple directions to obtain an asymmetric difference.

[0148] Reference Fig.23aIn the first experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.8 mm, an outer diameter in the 0 degree direction is 44.435, an outer diameter in the 45 degree direction is 44.538, an outer diameter in the 90 degree direction is 44.656, an outer diameter in the 135 degree direction is 44.398, an outer diameter in the 180 degree direction is 44.435, an outer diameter in the 225 degree direction is 44.538, an outer diameter in the 270 degree direction is 44.656, and an outer diameter in the 315 degree direction is 44.398. Among them, the difference between the maximum outer diameter 44.656 and the minimum outer diameter 44.398 is about 0.26. That is, in the first experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.8 mm, the asymmetry difference is about 0.26.

[0149] In addition, refer to Figure 23b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 23b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0150] Reference Fig.24a In the second experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.8 mm, an outer diameter in the 0 degree direction is 44.601, an outer diameter in the 45 degree direction is 44.704, an outer diameter in the 90 degree direction is 44.642, an outer diameter in the 135 degree direction is 44.552, an outer diameter in the 180 degree direction is 44.601, an outer diameter in the 225 degree direction is 44.704, an outer diameter in the 270 degree direction is 44.642, and an outer diameter in the 315 degree direction is 44.552. Among them, the difference between the maximum outer diameter 44.704 and the minimum outer diameter 44.552 is about 0.15. That is, in the second experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.8 mm, the asymmetry difference is about 0.15.

[0151] In addition, refer to Figure 24b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Figure 24b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0152] Reference Fig.25aIn the third experiment, the first chamfered portion 131 and the second chamfered portion 231 have a curvature radius of 0.8 mm, an outer diameter in the 0 degree direction is 44.500, an outer diameter in the 45 degree direction is 44.540, an outer diameter in the 90 degree direction is 44.599, an outer diameter in the 135 degree direction is 44.482, an outer diameter in the 180 degree direction is 44.500, an outer diameter in the 225 degree direction is 44.540, an outer diameter in the 270 degree direction is 44.599, and an outer diameter in the 315 degree direction is 44.482. Among them, the difference between the maximum outer diameter 44.599 and the minimum outer diameter 44.482 is about 0.12. That is, in the third experiment in which the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.8 mm, the asymmetry difference is about 0.12.

[0153] In addition, refer to Fig.25b It can be seen that the outer diameter of the electrode assembly 21 is the largest in the first rounded portion 131 of the first wound member 100 and the second rounded portion 231 of the second wound member 200. Fig.25b In FIG. 1 , the alternating long and short dashed lines with two arrows indicate the portion of the electrode assembly 21 having the largest outer diameter.

[0154] Reference Fig.26 When the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.2 mm, the average value of the asymmetric difference obtained in three experiments is 0.44 mm. When the curvature radius of the first chamfered portion 131 and the second chamfered portion 231 is 0.3 mm, the average value of the asymmetric difference obtained in three experiments is 0.41 mm. When the radius of curvature of the first chamfered portion 131 and the second chamfered portion 231 is 0.4mm, the average value of the asymmetric difference obtained in three experiments is 0.33mm; when the radius of curvature of the first chamfered portion 131 and the second chamfered portion 231 is 0.5mm, the average value of the asymmetric difference obtained in three experiments is 0.30mm; when the radius of curvature of the first chamfered portion 131 and the second chamfered portion 231 is 0.6mm, the average value of the asymmetric difference obtained in three experiments is 0.20mm; when the radius of curvature of the first chamfered portion 131 and the second chamfered portion 231 is 0.7mm, the average value of the asymmetric difference obtained in three experiments is 0.20mm; when the radius of curvature of the first chamfered portion 131 and the second chamfered portion 231 is 0.8mm, the average value of the asymmetric difference obtained in three experiments is 0.18mm.

[0155] Reference Fig.26 and Fig. 27Through the above experiment, it can be seen that as the curvature radius of the first rounded portion 131 and the second rounded portion 231 increases (that is, the curvature decreases), the asymmetric difference of the electrode assembly 21 decreases, thereby improving the shape asymmetry of the electrode assembly 21. In addition, it also has the effect of preventing cracks from being generated in the electrode due to the shape asymmetry of the electrode assembly 21. Fig. 27 , the X-axis direction represents the curvature radii of the first rounded portion 131 and the second rounded portion 231 , and the Y-axis direction represents the average value of the asymmetry difference.

[0156] However, if the curvature radius of the first rounded portion 131 and the second rounded portion 231 exceeds 0.8 mm, the difference in improving the asymmetry of the electrode assembly 21 is small, but the portion with the largest outer diameter of the electrode assembly 21 is randomly measured, making it difficult to predict the value. Therefore, the first rounded portion 131 of the first wound member 100 may have a curvature radius of 0.4 mm to 0.8 mm, and the second rounded portion 231 of the second wound member 200 may have a curvature radius of 0.4 mm to 0.8 mm.

[0157] This brings about the effect of improving the shape asymmetry of the electrode assembly 21 by optimizing the asymmetric difference of the electrode assembly 21 .

[0158] Fig.28 is a schematic cross-sectional view of a winding rod for an electrode assembly according to another embodiment of the present disclosure.

[0159] Reference Fig.28 , the first straight portion 120 of the first winding member 100 may have first fine protrusions 121 formed throughout the first straight portion 120 to prevent the diaphragm 23 from sliding. The plurality of first fine protrusions 121 may be provided in, for example, an embossing form.

[0160] In addition, second fine protrusions 221 may be formed on the second straight portion 220 of the second winding member 200 throughout the second straight portion 220 to prevent the diaphragm 23 from sliding. The plurality of second fine protrusions 221 may be provided in, for example, an embossing form.

[0161] In this embodiment, the first fine protrusions 121 may be formed only on the first winding member 100, the second fine protrusions 221 may be formed only on the second winding member 200, or the first fine protrusions 121 and the second fine protrusions 221 may be formed on the first winding member 100 and the second winding member 200, respectively.

[0162] As described above, since fine protrusions are formed on the winding members, when the separator 23 is sandwiched by the first and second winding members 100 and 200 , the separator 23 may be prevented from sliding, thereby preventing the asymmetry of the electrode assembly from being deteriorated.

[0163] Fig.29 is a diagram schematically illustrating a configuration of a battery pack including a cylindrical battery cell manufactured using a winding rod for an electrode assembly according to various embodiments of the present disclosure.

[0164] Reference Fig.29 , the battery pack 30 according to an embodiment of the present disclosure may include one or more cylindrical battery cells 20. Here, the cylindrical battery cell 20 is produced using the winding rod 10 for an electrode assembly according to the corresponding embodiment of the present disclosure described above.

[0165] In addition, the battery pack 30 may further include a battery pack case 31 for storing the cylindrical battery cells 20 , and various devices for controlling the charge and discharge of the cylindrical battery cells 20 , such as a BMS, a current sensor, a fuse, and the like.

[0166] Fig.30 It is shown that Fig.29 Diagram of a battery pack in a vehicle.

[0167] See also Fig.30 The vehicle 40 according to the embodiment of the present disclosure may include one or more cylindrical battery cells 20 or a battery pack 30. The cylindrical battery cell 20 is manufactured using the winding rod 10 for an electrode assembly according to the various embodiments of the present disclosure described above. In addition, the battery pack 30 may include one or more of the above-described cylindrical battery cells 20.

[0168] Here, the vehicle 40 may include various vehicles designed to use electric power, such as an electric vehicle or a hybrid vehicle.

[0169] Although terms indicating directions such as upward, downward, leftward, and rightward are used in the present specification, it is obvious to those skilled in the art that these terms are only for convenience of description and may vary depending on the position of a target object or the position of an observer.

[0170] As described above, although the present disclosure has been described with reference to limited embodiments and drawings, the present disclosure is not limited thereto, and within the scope of the technical ideas of the present disclosure and the equivalents of the claims to be described below, the technical personnel in the field to which the present disclosure belongs can make various modifications and changes. Therefore, the embodiments disclosed above should be considered to be intended to describe the embodiments of the present disclosure, rather than to limit the embodiments of the present disclosure. In other words, the true scope of the technical ideas of the present disclosure is shown in the claims, and all differences within the scope equivalent thereto should be interpreted as being included in the present disclosure.

[0171] Industrial Applicability

[0172] The present disclosure relates to a winding rod for an electrode assembly, a cylindrical battery cell manufactured using the winding rod, and a battery pack and a vehicle including the cylindrical battery cell, and is particularly applicable to industries related to secondary batteries.

Claims

1. A winding rod for an electrode assembly, the winding rod winding a jellyroll-type electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound in one direction, and the electrode assembly has a central hole formed at the center, the winding rod comprising: a first winding member inserted into the central hole of the electrode assembly; as well as a second winding member, the second winding member being inserted into the central hole of the electrode assembly so that the separator is interposed between the first winding member and the second winding member, and the second winding member being configured to wind the electrode assembly together with the first winding member, An asymmetry preventing portion is formed on at least one of the first winding member and the second winding member to prevent asymmetry of the electrode assembly.

2. The winding rod for an electrode assembly according to claim 1, in, An area of ​​the first winding member is different from an area of ​​the second winding member.

3. The winding rod for an electrode assembly according to claim 1, in, The cross-section of the first winding member comprises: a first curved portion formed into a curve; and A first straight line portion is configured to connect both ends of the first curved portion.

4. The winding rod for an electrode assembly according to claim 3, in, The asymmetry preventing portion includes a first rounded portion formed on both ends where the first curved portion and the first straight portion meet.

5. The winding rod for an electrode assembly according to claim 3, in, The asymmetry preventing portion includes a first chamfered portion formed on both ends where the first curved portion and the first straight portion meet.

6. The winding rod of the electrode assembly according to claim 3, in, The asymmetry preventing portion includes a first wavy pattern portion formed on both ends where the first curved portion and the first straight portion meet.

7. The winding rod for an electrode assembly according to claim 1, in, The cross-section of the second winding member includes: a second curved portion, the second curved portion being formed into a curve; and A second straight line portion is configured to connect both ends of the second curved portion.

8. The winding rod for an electrode assembly according to claim 7, in, The asymmetry preventing portion includes a second rounded portion formed on both ends where the second curved portion and the second straight portion meet.

9. The winding rod of the electrode assembly according to claim 7, in, The asymmetry preventing portion includes a second chamfered portion formed on both ends where the second curved portion and the second straight portion meet.

10. The winding rod for an electrode assembly according to claim 7, in, The asymmetry preventing portion includes a second wavy pattern portion formed on both ends where the second curved portion and the second straight line portion meet.

11. The winding rod for an electrode assembly according to claim 4, in, The first rounded portion has a curvature radius of 0.4 mm to 0.8 mm.

12. The winding rod of the electrode assembly according to claim 8, in, The second rounded portion has a curvature radius of 0.4 mm to 0.8 mm.

13. The winding rod of the electrode assembly according to claim 3, in, The first straight line portion includes a first fine protrusion formed throughout the first straight line portion to prevent the diaphragm from sliding.

14. The winding rod for an electrode assembly according to claim 7, in, The second straight line portion includes a second fine protrusion formed throughout the second straight line portion to prevent the diaphragm from sliding.

15. A cylindrical battery cell produced using the winding rod for an electrode assembly according to any one of claims 1 to 14.

16. A battery pack comprising at least one cylindrical battery cell according to claim 15.

17. A vehicle comprising at least one cylindrical battery cell according to claim 15.

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