Cylindrical battery cells and current collectors applied thereto, as well as battery packs and automobiles including the same.

Abstract

A cylindrical battery cell according to one embodiment of the present invention is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separator interposed between them around a winding axis, wherein the first electrode is not coated with an active material layer on its long side end along the winding direction and includes a first plain portion exposed to the outside of the separator, at least a portion of the first plain portion being used as an electrode tab by itself, and the electrode assembly having an opening on one side and accommodating the electrode assembly through the opening A current collector comprising: a configured battery can; cell terminals configured to penetrate the surface opposite to the opening of the battery can; a peripheral portion located on the upper part of the electrode assembly; a first plain portion connecting portion extending inward from the peripheral portion and welded to a first plain portion; and a terminal connecting portion located spaced apart from the first plain portion connecting portion and welded to a cell terminal, wherein a plurality of welds are provided between the first plain portion and the current collector, and the current collector is configured such that the angles between adjacent welds among the plurality of welds are acute angles.

Description

Technical Field

[0001] The present invention relates to a cylindrical battery cell, a current collector applied thereto, a battery pack including the same, and an automobile.

[0002] This application claims priority based on Korean Patent Application No. 10-2023-0137148 filed on October 13, 2023, and all the contents disclosed in the specification and drawings of the application are incorporated herein.

Background Art

[0003] The application fields of secondary batteries are extremely diverse. Among these, for example, battery packs applied to devices such as electric vehicles are required to have a large capacity and high output. Also, such battery packs with a large capacity and high output may include, for example, cylindrical battery cells as unit cells.

[0004] In a cylindrical battery cell having large capacity and high output characteristics, in order to improve the current collection efficiency, electrode tabs are provided over the entire both sides of a jelly roll, and current collectors can be respectively bonded onto both sides of the jelly roll. By applying such a structure, the contact area between the electrode tab and the current collector can be maximized, and thereby the resistance generated at the connection part between components can be minimized.

[0005] On the other hand, as a factor increasing the circuit resistance of a secondary battery, there is a welding part connecting the current collector and the electrode assembly. When the welding part increases, problems in the process such as melting of the separator and / or welding splatter may occur. Therefore, not only minimizing the resistance but also minimizing the welding part becomes an important issue.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in consideration of the above problems, and one of its purposes is to minimize the internal resistance of a secondary battery.

[0007] Another objective of the present invention is to minimize the welded portion of the secondary battery.

[0008] More specifically, the present invention also aims to minimize process problems such as separator melting and / or welding splatter.

[0009] Furthermore, the technical problems that this invention aims to solve are not limited to those described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention below. [Means for solving the problem]

[0010] A cylindrical battery cell according to one embodiment of the present invention for solving the above-mentioned problems is an electrode assembly in which a core and an outer surface are defined by winding a first electrode, a second electrode, and a separator interposed between them around a winding axis, wherein the first electrode is not coated with an active material layer on the long side end along the winding direction and includes a first plain portion exposed to the outside of the separator, at least a portion of the first plain portion being used as an electrode tab by itself, and the electrode assembly having an opening on one side, through which the electrode assembly is housed A current collector comprising: a battery can configured in such a way; a cell terminal configured to penetrate the surface of the battery can opposite to the opening; a peripheral portion located on the upper part of the electrode assembly; a first plain portion connecting portion extending inward from the peripheral portion and welded to the first plain portion; and a terminal connecting portion located spaced apart from the first plain portion connecting portion and welded to the cell terminal, wherein a plurality of welds are provided between the first plain portion and the current collector, and the current collector is configured such that the angles between adjacent welds among the plurality of welds are acute angles.

[0011] In one embodiment of the present invention, the first blank portion connecting portion and the terminal connecting portion can be electrically connected by the peripheral portion.

[0012] Preferably, the angles between adjacent welds among the plurality of welds can be configured to be 45 degrees or less.

[0013] In another embodiment of the present invention, at least one first weld may be provided between the first plain portion and the first plain portion joining portion.

[0014] For example, the first welded portion may be configured to exhibit a linear shape along the extending direction of the first plain portion joint.

[0015] In yet another embodiment of the present invention, the current collector may further include a connecting portion that extends inward from the peripheral portion and is connected to the terminal coupling portion.

[0016] Here, at least one second welded portion may be provided between the first plain portion and the connecting portion.

[0017] For example, the second weld may be configured to be linear in shape along the extending direction of the connection.

[0018] Preferably, the angle between adjacent welds among the first and second welds may be configured to be 45 degrees or less.

[0019] In one embodiment of the present invention, at least one of the first plain portion joining portion and the connecting portion may be provided in multiple quantities.

[0020] In another embodiment of the present invention, the connecting portion may be located between a pair of adjacent first plain portion connecting portions.

[0021] In yet another embodiment of the present invention, at least one of the first weld and the second weld may be provided in multiple locations.

[0022] On the other hand, a battery pack according to one embodiment of the present invention includes a cylindrical battery cell according to one embodiment of the present invention and a pack housing that accommodates a plurality of the cylindrical battery cells.

[0023] An automobile according to an embodiment of the present invention includes a battery pack according to an embodiment of the present invention as described above.

[0024] On the other hand, a current collector according to an embodiment of the present invention for solving the above problems includes an electrode assembly including a first non-textured portion and a second non-textured portion; a battery can that houses the electrode assembly through an opening formed on one side and is electrically connected to the second non-textured portion; and a cell terminal that is electrically connected to the first non-textured portion. The current collector is applied to a cylindrical battery cell and includes a peripheral portion that is interposed between a closing portion of the battery can located on the opposite side of the opening and the electrode assembly, is bonded to one surface of the electrode assembly, and is disposed on one surface of the electrode assembly; a first non-textured portion coupling portion that extends inward from the peripheral portion and is welded and coupled to the first non-textured portion; and a terminal coupling portion that is spaced apart from the first non-textured portion coupling portion and is welded and coupled to the cell terminal. A plurality of welding portions are provided between the first non-textured portion and the current collector, and the angle between adjacent welding portions among the plurality of welding portions can be configured to be 45 degrees or less.

Advantages of the Invention

[0025] According to one aspect of the present invention, the internal resistance of a secondary battery can be effectively reduced.

[0026] According to another aspect of the present invention, the welding portions of a secondary battery can be minimized.

[0027] Thereby, problems in the process such as melting of the separator and / or welding spatter can be minimized.

[0028] Note that the technical effects obtained by the present invention are not limited to the above effects, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0029] The drawings accompanying this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described later, serve to further illustrate the technical idea of ​​the present invention. Therefore, the present invention is not to be construed as being limited only to what is shown in the drawings. [Brief explanation of the drawing]

[0030] [Figure 1] This figure shows the external appearance of a cylindrical battery cell according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the internal structure of a cylindrical battery cell according to one embodiment of the present invention. [Figure 3] This diagram illustrates the electrode assembly, cell terminals, and current collector included in the cylindrical battery cell shown in Figure 1. [Figure 4] This is a diagram illustrating the welded joint between the electrode assembly and the current collector. [Figure 5] This diagram illustrates the current collector included in the cylindrical battery cell shown in Figure 1. [Figure 6] This diagram illustrates a conventional configuration in which a current collector is welded to an electrode assembly. [Figure 7] This diagram illustrates a configuration in which a current collector according to one embodiment of the present invention is welded to an electrode assembly. [Figure 8] This figure illustrates a configuration in which a current collector according to another embodiment of the present invention is welded to an electrode assembly. [Figure 9] This figure illustrates a configuration in which a current collector according to yet another embodiment of the present invention is welded to an electrode assembly. [Figure 10] This figure illustrates a configuration in which a current collector according to yet another embodiment of the present invention is welded to an electrode assembly. [Figure 11] This graph shows the internal resistance of a cylindrical battery cell according to one embodiment of the present invention and a battery cell according to a comparative example. [Figure 12] This graph shows the internal resistance of a cylindrical battery cell according to one embodiment of the present invention and a battery cell according to a comparative example. [Figure 13]This figure shows a schematic configuration of a battery pack including a cylindrical battery cell according to one embodiment of the present invention. [Figure 14] This figure shows a schematic configuration of a vehicle including a battery pack according to one embodiment of the present invention. [Modes for carrying out the invention]

[0031] Preferred embodiments of the present invention will now be described in detail based on the accompanying drawings. Prior to this, terms and words used in this specification and in the claims are not to be interpreted in their usual or dictionary sense, but rather in a sense and concept consistent with the technical idea of ​​the present invention, in accordance with the principle that the inventor may appropriately define the concept of a term in order to best describe the invention. Therefore, it should be understood that the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be a variety of equivalent and modified embodiments that can be substituted therein at the time of this application.

[0032] Furthermore, to aid in understanding the invention, the accompanying drawings are not shown to actual scale, and the dimensions of some components may be exaggerated. Also, the same components may be given the same reference numerals in different embodiments.

[0033] The statement that two comparison objects are identical means that they are "substantially identical." Therefore, "substantially identical" may include deviations that are considered low in the industry, for example, deviations of 5% or less. Furthermore, the statement that a parameter is uniform in a given domain may mean that it is uniform in that domain from an average perspective.

[0034] Figure 1 is a diagram showing the external appearance of a cylindrical battery cell according to one embodiment of the present invention, and Figure 2 is a cross-sectional view showing the internal structure of a cylindrical battery cell according to one embodiment of the present invention.

[0035] Referring to Figures 1 and 2, a cylindrical battery cell 1 according to one embodiment of the present invention includes an electrode assembly 10, a battery can 20, cell terminals 30, and a current collector 40.

[0036] In addition to the components described above, the cylindrical battery cell 1 may further include an insulating gasket G2 and / or a second current collector.

[0037] The electrode assembly 10 includes a first electrode having a first polarity, a second electrode having a second polarity, and a separator interposed between the first electrode and the second electrode. The first electrode is either a positive or negative electrode, and the second electrode corresponds to an electrode having the opposite polarity to the first electrode.

[0038] The electrode assembly 10 may have, for example, a jelly-roll structure. That is, the electrode assembly 10 can be manufactured by winding a laminate formed by stacking a sheet-like first electrode current collector 40, a second electrode current collector 40, and a separator interposed between them at least once, in one direction with respect to the winding center C. In this case, an additional separator may be provided on the outer surface of the electrode assembly 10 for insulation from the battery can 20. Any jelly-roll structure known in the industry can be applied to the present invention without limitation.

[0039] The first electrode includes a first electrode current collector 40 and a first electrode active material coated on one or both sides of the first electrode current collector 40. At one end of the first electrode current collector 40 in the width direction (along the Z-axis), there is a first blank portion 11 where the first electrode active material is not coated. The blank portion, which functions as a first electrode tab, will hereinafter be referred to as the first blank portion 11. The first blank portion 11 is provided at the top of the electrode assembly 10 housed in the battery can 20 in the height direction (along the Z-axis). That is, the first electrode current collector 40 includes a first blank portion 11 exposed to the outside of the separator, where the active material layer is not coated on the long side end, and at least a part of the first blank portion 11 is used as an electrode tab itself. The first blank portion 11 may be, for example, a positive electrode tab.

[0040] On the other hand, at least a portion of the first plain section 11 may include a plurality of segmented pieces divided along the winding direction of the electrode assembly 10. In this case, the plurality of segmented pieces may be bent along the radial direction of the electrode assembly 10. The bent plurality of segmented pieces may overlap in multiple layers. In this case, the first plain section joining section 42, which will be described later, may be joined to the region where the plurality of segmented pieces overlap in multiple layers.

[0041] The second electrode includes a second electrode current collector 40 and a second electrode active material coated on one or both sides of the second electrode current collector 40. At the other end of the second electrode current collector 40 in the width direction (along the Z-axis), there is a first blank portion 11 where the second electrode active material is not coated. The first blank portion 11, which functions as a second electrode tab, will hereinafter be referred to as the second blank portion 12. The second blank portion 12 is provided at the bottom of the electrode assembly 10 housed in the battery can 20 in the height direction (along the Z-axis). That is, the second electrode current collector 40 includes a second blank portion 12 exposed to the outside of the separator, where the active material layer is not coated on the long side end, and at least a part of the second blank portion 12 is used as an electrode tab itself. The second blank portion 12 may be, for example, a negative electrode tab. On the other hand, at least a portion of the second plain portion 12 may include a plurality of segmented pieces divided along the winding direction of the electrode assembly 10. In this case, the plurality of segmented pieces may be bent along the radial direction of the electrode assembly 10. The bent plurality of segmented pieces may overlap in multiple layers. In this case, the second current collector may be coupled to the region where the plurality of segmented pieces overlap in multiple layers.

[0042] The first blank portion 11 and the second blank portion 12 extend in opposite directions along the height direction (direction along the Z-axis) of the cylindrical battery cell 1. The first blank portion 11 extends toward the closing portion of the battery can 20, and the second blank portion 12 extends toward the opening of the battery can 20.

[0043] In the present invention, the positive electrode active material applied to the positive electrode plate and the negative electrode active material applied to the negative electrode plate can be any active material known in the industry without limitation.

[0044] Figure 3 is a diagram illustrating the electrode assembly 10, cell terminals 30, and current collector 40 included in the cylindrical battery cell shown in Figure 1.

[0045] Referring to Figure 3, the structure of the electrode assembly 10 will be described in more detail. In the following description, the first electrode will be used as an example, but the structure of this first electrode is similarly applicable to the second electrode.

[0046] Preferably, the first blank area 11 may include a plurality of notched segments 11a. The plurality of segments 11a constitute a plurality of groups, and the segments 11a belonging to each group may have substantially the same height (length in the Z direction) and / or width (length in the X direction) and / or spacing pitch. The number of segments 11a belonging to each group can be increased or decreased from those shown.

[0047] The plain sections 11 and 12 can be bent along the radial direction of the electrode assembly 10, for example, from the outer periphery to the core. When the plain sections 11 and 12 are bent, multiple layers of radially adjacent segments overlap, forming bent surfaces on the upper and lower parts of the electrode assembly 10.

[0048] The battery can 20 may be configured to include an opening on one side, through which the electrode assembly 10 is housed.

[0049] Specifically, the battery container 20 is a substantially cylindrical housing with an opening formed at the bottom, and is made of a conductive material such as metal. Examples of materials for the battery container 20 include steel, stainless steel, or nickel-plated iron. The upper surface located opposite the opening is referred to as the closing portion. The side wall and closing portion of the battery container 20 may be formed integrally. Alternatively, the side wall and closing portion of the battery container 20 may be provided separately and joined together by welding or other means. The upper surface of the battery container 20 (the surface parallel to the XY plane), i.e., the outer surface 20a of the closing portion, may have a substantially flat shape. The battery container 20 houses the electrode assembly 10 through the opening formed at the bottom, and also houses the electrolyte.

[0050] The battery can 20 is electrically connected to the electrode assembly 10. The battery can 20 is electrically connected, for example, to the second blank portion 12 of the electrode assembly 10. In this case, the battery can 20 has the same polarity as the second blank portion 12.

[0051] Figure 4 is a diagram illustrating the welded joint W between the electrode assembly 10 and the current collector 40.

[0052] Referring to Figures 1 to 4, the cell terminal 30 is made of a conductive metallic material. For example, aluminum (Al) may be used as the material for the cell terminal 30. When the material of the cell terminal 30 is aluminum, the processability during riveting may be improved. Aluminum of the 10 series, which has relatively low electrical resistance, may be used for the cell terminal 30. The cell terminal 30 penetrates the upper surface of the battery can 20, i.e., the surface located opposite the opening of the battery can 20 (a surface parallel to the XY plane). The cell terminal 30 is electrically connected, for example, to the first blank portion 11 of the electrode assembly 10. In this case, the cell terminal 30 has a first polarity. Therefore, the cell terminal 30 can function as a first electrode terminal in the cylindrical battery cell 1 of the present invention. When the cell terminal 30 has a first polarity in this way, the cell terminal 30 is electrically insulated from the battery can 20, which has a second polarity. Electrical insulation between the cell terminal 30 and the battery can 20 can be achieved by various methods. For example, insulation can be achieved by interposing an insulating gasket G2 between the cell terminal 30 and the battery can 20. Alternatively, insulation can be achieved by forming an insulating coating layer on a part of the cell terminal 30. Or, a method can be adopted to structurally fix the cell terminal 30 so that it cannot come into contact with the battery can 20. Furthermore, it is possible to combine and apply several of the above methods. The cell terminal 30 can be rivet-bonded to the closed portion of the battery can 20.

[0053] Referring to Figures 2 and 3, the connection between the bottom surface of the central region of the cell terminal 30 and the current collector 40 can be performed, for example, by laser welding, spot welding, or ultrasonic welding.

[0054] The welding can be performed by irradiating a laser through a hole formed in the winding center C of the electrode assembly 10, or by inserting a tool for ultrasonic welding or spot welding to form a weld bead on one surface of the current collector 40 (the surface facing the hole formed in the winding center C of the electrode assembly 10).

[0055] With this structure, the cylindrical battery cell 1 according to one embodiment of the present invention can ensure a smooth current flow at the connection between the current collector 40 and the cell terminal 30 when a large amount of current flows due to rapid charging, thereby achieving effects such as shortening the charging time and reducing the amount of heat generated.

[0056] The insulating gasket G2 may be interposed between the outer surface 20a of the closed portion of the battery can 20 and the cell terminals 30. The insulating gasket G2 may be made of, for example, a resin material having insulating and elastic properties. Therefore, the insulating gasket G2 can electrically insulate the battery can 20 and the cell terminals 30.

[0057] Referring to Figures 3 to 5, the current collector 40 is coupled to the upper part of the electrode assembly 10. The current collector 40 is made of a conductive metallic material and is connected to the first blank portion 11. More specifically, the current collector 40 can be welded to the upper part of the electrode assembly 10.

[0058] The current collector 40 can be welded onto a coupling surface (bent surface) formed by bending the end of the first blank portion 11 in a direction parallel to the current collector 40. The bending direction of the first blank portion 11 may be in the radial direction of the electrode assembly 10. For example, the bending direction of the first blank portion 11 may be toward the winding center C of the electrode assembly 10. When the first blank portion 11 has such a bent shape, the space occupied by the first blank portion 11 is reduced, which can lead to an improvement in energy density. In addition, by increasing the coupling area between the first blank portion 11 and the current collector 40, it is possible to obtain the effect of improving coupling force and reducing contact resistance.

[0059] Referring to Figures 3 to 5, at least a portion of the first blank section 11 and / or the second blank section 12 may include a plurality of segmented pieces 11a divided along the winding direction of the electrode assembly 10. In this case, the plurality of segmented pieces may be bent along the radial direction of the electrode assembly 10. The bent plurality of segmented pieces may overlap in multiple layers. In this case, the first blank section coupling portion 42 of the current collector 40, which will be described later, may be coupled to the region where the plurality of segmented pieces overlap in multiple layers.

[0060] The first current collector 40 electrically connects the first blank portion 11 of the electrode assembly 10 to the cell terminal 30. The first current collector 40 is made of a conductive metal material.

[0061] Referring to Figure 5, the current collector 40 includes a peripheral portion 41, a first plain portion connecting portion 42, and a terminal connecting portion 43. The peripheral portion 41 is positioned on the upper part of the electrode assembly 10 and may have a substantially rim shape with a space S formed inside. In the drawings of the present invention, only an example in which the peripheral portion 41 has a substantially circular rim shape is shown, but the present invention is not limited thereto.

[0062] The first plain portion joining portion 42 extends inward from the peripheral portion 41 and is joined to the first plain portion 11. Preferably, the first plain portion joining portion 42 extends inward from the peripheral portion 41 and is welded to the first plain portion 11. In this case, a welded portion W may be provided between the first plain portion joining portion 42 and the first plain portion 11.

[0063] It is desirable that the connection between the current collector 40 and the first blank portion 11 is formed to overlap by at least approximately 50% with the welding target region, which is a section where the number of overlapping layers of the divided pieces is approximately the maximum and is maintained approximately constant. That is, the first blank portion connection portion 42 of the current collector 40 can be connected to the first blank portion 11 such that it overlaps by at least approximately 50% with the welding target region.

[0064] The terminal coupling portion 43 is spaced apart from the first plain portion coupling portion 42 and is located inside the peripheral portion 41. The terminal coupling portion 43 can be joined to the cell terminal 30 by welding. The terminal coupling portion 43 may have a diameter substantially equal to or greater than the diameter of the flat portion formed on the bottom surface of the cell terminal 30 in order to secure a welding area for joining with the flat portion formed on the bottom surface of the cell terminal 30.

[0065] In one embodiment of the present invention, a plurality of welded joints W are provided between the first plain portion 11 and the current collector 40, and the angles between adjacent welded joints W may be acute. Here, the welded joints W may include at least one of the first welded joint W1 and the second welded joint W2, which will be described later.

[0066] Figure 6 is a diagram illustrating a conventional configuration in which a current collector 40 is welded to an electrode assembly 10, and Figure 7 is a diagram illustrating a configuration in which a current collector 40 according to one embodiment of the present invention is welded to an electrode assembly 10.

[0067] For example, referring to Figure 6, in the conventional current collector 40, the angle between adjacent welded parts W was approximately 90 degrees. However, when the angle between adjacent welded parts W is greater than approximately 90 degrees, a problem arises in that the internal resistance of the battery increases.

[0068] On the other hand, referring to Figure 7, which is one embodiment of the present invention, a plurality of welds W are provided between the current collector 40 and the electrode assembly 10, and the angles between adjacent welds W are configured to be acute. More specifically, in the embodiment of Figure 2, the angles between adjacent welds W are configured to be approximately 45 degrees. In this way, since the angles between adjacent welds W among the plurality of welds W provided between the first blank portion 11 and the current collector 40 are configured to be acute, the internal resistance of the battery (ACIR: Alternating Current Internal Resistance) can be effectively reduced. Furthermore, with such a structure, process problems such as melting of the separator and / or welding splatter can also be minimized.

[0069] The first blank portion connecting portion 42 and the terminal connecting portion 43 are not directly connected and may be spaced apart from each other. The first blank portion connecting portion 42 and the terminal connecting portion 43 are electrically connected by the peripheral portion 41. Thus, in this embodiment of the present invention, the current collector 40 has a structure in which the first blank portion connecting portion 42 and the terminal connecting portion 43 are not directly connected but are connected by the peripheral portion 41. This allows the impact applied to the connection portion between the first blank portion connecting portion 42 and the first blank portion 11 and the connection portion between the terminal connecting portion 43 and the cell terminal 30 to be dispersed when the cylindrical battery cell 1 is subjected to impact and / or vibration. Therefore, the current collector 40 of the present invention can minimize or prevent damage to the welded portion W due to external impact.

[0070] Figure 7 is a diagram illustrating a configuration in which a current collector 40 according to one embodiment of the present invention is welded to an electrode assembly 10, and Figure 8 is a diagram illustrating a configuration in which a current collector 40 according to another embodiment of the present invention is welded to an electrode assembly 10.

[0071] Preferably, the angles between adjacent welds W can be configured to be approximately 45 degrees or less.

[0072] For example, referring to Figures 7 and 8, the angle between adjacent welds W is configured to be approximately 45 degrees. With such a structure, the internal resistance of the battery can be significantly reduced compared to conventional cylindrical battery cells where the angle between adjacent welds W is approximately 90 degrees. Furthermore, with such a structure, process problems such as separator melting and / or welding splatter can be minimized. However, if the angle between adjacent welds W is set to be excessively small, the time and cost required for the process may increase, potentially reducing process efficiency. Specific effects and numerical values ​​will be discussed in detail later, referring to the experimental graphs in Figures 11 and 12.

[0073] The current collector 40 may further include a connecting portion 44 that extends inward from the peripheral portion 41 and is connected to the terminal coupling portion 43.

[0074] The connecting portion 44 may have a tapered portion 44a that narrows in width along the direction from the inner surface of the peripheral portion 41 toward the terminal connecting portion 43. That is, the tapered portion 44a may have a shape in which its width widens along the direction from the connection point between the terminal connecting portion 43 and the peripheral portion 41 toward the peripheral portion 41. The change in width of the tapered portion 44a may be continuous or stepwise. When the tapered portion 44a is provided, the rigidity of the component may be improved at the connection point between the connecting portion 44 and the peripheral portion 41. Furthermore, when the tapered portion 44a is provided, in the manufacturing process of the cylindrical battery cell 1, for example, the current collector 40 and / or the assembly of the current collector 40 and the electrode assembly 10 can be easily and safely transported by a transport device and / or an operator gripping the tapered portion 44a. In other words, if the tapered portion 44a is provided, it is possible to prevent product defects that may occur due to gripping a part that is welded to another part, such as the first plain portion joint 42 or the terminal joint 43.

[0075] On the other hand, multiple first blank portion connecting portions 42 may be provided. When multiple first blank portion connecting portions 42 are provided, the multiple first blank portion connecting portions 42 may be arranged radially, for example, with respect to the center of the terminal connecting portion 43. The drawings of the present invention show only cases where the number of first blank portion connecting portions 42 is 3, 4, and 6, but the present invention is not limited thereto. The number of first blank portion connecting portions 42 can be determined in various ways, taking into consideration the resistance level required for the cylindrical battery cell 1, the aperture ratio of the first current collector 40, and so on. Multiple first blank portion connecting portions 42 may be arranged regularly along the extending direction of the peripheral portion 41. For example, multiple first blank portion connecting portions 42 may be arranged at substantially equal intervals along the extending direction of the peripheral portion 41. The extending lengths of each of the multiple first blank portion connecting portions 42 may be substantially the same as those of the others. The first plain portion joining portion 42 can be joined to the first plain portion 11 by welding.

[0076] The terminal coupling portion 43 may be arranged so as to be surrounded by a plurality of the first plain portion coupling portions 42. The terminal coupling portion 43 may be joined to the cell terminal 30 by welding. The connecting portion 44 may be located between a pair of adjacent first plain portion coupling portions 42. In this case, the distance from the connecting portion 44 to either of the pair of first plain portion coupling portions 42 along the extending direction of the peripheral portion 41 may be substantially the same as the distance from the connecting portion 44 to the other of the pair of first plain portion coupling portions 42 along the extending direction of the peripheral portion 41. The cross-sectional area of ​​each of the plurality of first plain portion coupling portions 42 may be formed to be substantially the same. The width and thickness of each of the plurality of first plain portion coupling portions 42 may also be formed to be substantially the same.

[0077] Multiple connection portions 44 may be provided. The number of connection portions 44 may be determined considering the required resistance level for the cylindrical battery cell 1, the aperture ratio of the first current collector 40, and so on. Each of the multiple connection portions 44 may be positioned between a pair of adjacent first plain portion connection portions 42. The multiple connection portions 44 may be arranged regularly with respect to each other along the extending direction of the peripheral portion 41. For example, the multiple connection portions 44 may be arranged at substantially equal intervals along the extending direction of the peripheral portion 41. On the other hand, the distance from each of the multiple connection portions 44 to either of a pair of adjacent first plain portion connection portions 42 along the extending direction of the peripheral portion 41 may be substantially the same as the distance to the other.

[0078] As described above, when multiple first blank section joining portions 42 and / or connecting portions 44 are provided, if the spacing between the first blank section joining portions 42 and / or the spacing between the connecting portions 44 and / or the distance between the first blank section joining portions 42 and the connecting portions 44 is formed to be substantially constant, then a current flow from the first blank section joining portion 42 to the connecting portion 44, or from the connecting portion 44 to the first blank section joining portion 42, can be formed smoothly.

[0079] The connection between the current collector 40 and the first blank portion 11 can be achieved by welding. In this case, for example, laser welding, ultrasonic welding, spot welding, etc., may be applied.

[0080] In one embodiment of the present invention, at least one first weld W1 may be provided between the first plain portion 11 and the first plain portion joining portion 42. Preferably, the first weld W1 may be configured to be linear along the extending direction of the first plain portion joining portion 42.

[0081] For example, referring to Figure 7, a first welded portion W1 is provided linearly between the first plain portion 11 and the first plain portion joining portion 42. However, embodiments of the present invention are not limited to linear shapes. For example, elliptical and zigzag shapes may also be included in the scope of the present invention for the convenience of welding. Since the first welded portion W1 is formed on the first plain portion joining portion 42 which extends in the radial direction, the overall shape of the first welded portion W1 may be a shape that extends long in the radial direction. That is, if the first welded portion W1 is, for example, elliptical, the elliptical shape may be an elliptical shape that extends long along the radial direction. For example, if the first welded portion W1 is zigzag, it may be a zigzag shape that extends long along the radial direction.

[0082] In another embodiment of the present invention, at least one second weld W2 may be provided between the first plain portion 11 and the connecting portion 44. Preferably, the second weld W2 may be configured to be linear along the extending direction of the first plain portion connecting portion 42.

[0083] For example, referring to Figure 7, at least one second weld W2 is provided between the first plain portion 11 and the connecting portion 44. However, embodiments of the present invention are not limited to linear shapes. For example, elliptical and zigzag shapes may also be included in the scope of the present invention for the convenience of welding. Since the second weld W2 is formed on the connecting portion 44 which extends in the radial direction, the overall shape of the second weld W2 may be a shape that extends long in the radial direction. That is, if the second weld W2 is, for example, elliptical, the elliptical shape may be an elliptical shape that extends long along the radial direction. For example, if the second weld W2 is zigzag, it may be a zigzag shape that extends long along the radial direction.

[0084] In yet another embodiment of the present invention, at least one of the first weld W1 and the second weld W2 may be provided in multiple locations.

[0085] For example, referring to Figure 7, multiple first welds W1 and multiple second welds W2 may be provided. On the other hand, although not shown, multiple first welds W1 may be provided, or multiple second welds W2 may be provided.

[0086] Thus, with a structure in which at least one of the first weld W1 and the second weld W2 is provided in multiple locations, the welding area can be increased, thereby reducing the internal resistance of the battery. Furthermore, with such a structure, the angle between adjacent welds W can be reduced. This minimizes process problems such as melting of the separator and / or welding splatter. Specific effects and numerical values ​​will be described in detail later with reference to the experimental graphs in Figures 11 and 12.

[0087] In one embodiment of the present invention, referring to Figure 7, the angle between adjacent welds W of the first weld W1 and the second weld W2 may be configured to be acute. Preferably, the angle between adjacent welds W of the first weld W1 and the second weld W2 may be configured to be 45 degrees or less.

[0088] In another embodiment of the present invention, referring to Figure 8, the first plain section joint 42 may be configured to be directly connected to the terminal joint 43. That is, in this case, the first plain section joint 42 can itself become the connection 44. In the embodiment of Figure 8, the first plain section joint 42 can become the connection 44 as is, and welds W may be provided in all parts connecting the peripheral section 41 and the terminal joint 43. In this case, the angle between adjacent welds W may be, for example, about 45 degrees or less.

[0089] Figure 9 is a diagram illustrating a configuration in which the current collector 40 is welded to the electrode assembly 10 according to yet another embodiment of the present invention.

[0090] In yet another embodiment of the present invention, the angles between adjacent welds W among the plurality of welds W may be configured to be 60 degrees or less.

[0091] For example, referring to Figure 9, three first plain section joints 42 may be provided at intervals of approximately 120 degrees. At the same time, three connecting sections 44 may also be provided at intervals of approximately 120 degrees. Here, the first plain section joints 42 and the connecting sections 44 may be arranged alternately. In this case, the first welded section W1 provided on the first plain section joint 42 and the second welded section W2 provided on the adjacent connecting section 44 may be configured to be spaced at an angle of approximately 60 degrees from each other.

[0092] This structure can reduce the internal resistance of the battery. Furthermore, it can minimize process problems such as separator melting and / or welding splatter.

[0093] Figure 10 is a diagram illustrating a configuration in which the current collector 40 is welded to the electrode assembly 10 according to yet another embodiment of the present invention.

[0094] In yet another embodiment of the present invention, the angles between adjacent welds W among the plurality of welds W may be configured to be 30 degrees or less.

[0095] For example, referring to Figure 10, six first plain section joints 42 may be provided at intervals of approximately 60 degrees. At the same time, six connecting sections 44 may also be provided at intervals of approximately 60 degrees. Here, the first plain section joints 42 and the connecting sections 44 may be arranged alternately. In this case, the first welded section W1 provided on the first plain section joint 42 and the second welded section W2 provided on the adjacent connecting section 44 may be configured to be spaced approximately 30 degrees apart from each other.

[0096] This structure allows for further reduction of the battery's internal resistance. It also minimizes process issues such as separator melting and / or welding splatter.

[0097] The following discussion will examine the changes in battery internal resistance due to changes in welding area and changes in welding angle, referring to Figures 11 and 12.

[0098] <Experiment 1> Figure 11 is a graph showing the internal resistance of a cylindrical battery cell according to one embodiment of the present invention and a battery cell according to a comparative example.

[0099] The experiment shown in Figure 11 was carried out in 4695 cells by welding the current collector 40 shown in Figure 5 onto the electrode assembly 10. In Experiment Example 1, the current collector 40 shown in Figure 5 was placed on the electrode assembly 10 and welded to the first blank joint 42 to form four linear first welds W1. That is, the current collector 40 shown in Figure 5 has four first blank joints 42 spaced approximately 90 degrees apart, and one first weld W1 was formed on each of the four first blank joints 42.

[0100] In Experimental Example 2, the current collector 40 shown in Figure 5 was placed on the electrode assembly 10 and welded to the first blank section joint 42 to form eight linear first welds W1. Specifically, the current collector 40 in Figure 5 has four first blank section joints 42 spaced approximately 90 degrees apart, and two first welds W1 were formed on each of the four first blank section joints 42. As a result, the positions of the first welds W1 in Experimental Example 2 were the same as those in Experimental Example 1, and the area of ​​the first welds W1 in Experimental Example 2 was twice the area of ​​the first welds W1 in Experimental Example 1.

[0101] In other words, Experiment 1 measured the changes in resistance and standard deviation when only the welding area was changed while keeping the welding angle the same. The results of measuring the internal resistance (ACIR) of the batteries in Experiment 1 and Experiment 2 are shown in Table 1 and the graph in Figure 11 below. For reference, the resistance values ​​shown in Table 1 and Figure 11 represent the resistance values ​​before activation.

[0102] [Table 1]

[0103] As can be seen from Table 1 and Figure 11 above, when the welding area increased by approximately twofold in Experiment 2 compared to Experiment 1, the standard deviation decreased significantly from 0.0768 to 0.0193. On the other hand, it can be confirmed that there was no significant change in the resistance value itself despite the welding area increasing by approximately twofold in Experiment 2 compared to Experiment 1. Specifically, although the resistance was slightly higher in Experiment 2 compared to Experiment 1, it is estimated that this is within the range of measurement error rather than being due to the effect of the area. In other words, from the results of Experiment 1, it was confirmed that, in the shape of the current collector 40 in Figure 5, if a certain level of welding area is secured with 4 lines, further increases in welding area do not have a significant effect on the resistance value. In addition, it was confirmed from Experiment 1 that an increase in welding area significantly reduces the standard deviation of resistance.

[0104] <Experiment 2> Figure 12 is a graph showing the internal resistance of a cylindrical battery cell according to one embodiment of the present invention and a battery cell according to a comparative example.

[0105] The experiment in Figure 12 was carried out by welding the current collector 40 shown in Figure 5 onto the electrode assembly 10 in a 4680 cell. In Comparative Example 1, the current collector 40 shown in Figure 5 was placed on the electrode assembly 10 and welded to the first blank joint 42 to form one linear first weld W1 line. That is, the current collector 40 in Figure 5 has four first blank joints 42 provided at intervals of approximately 90 degrees, and one first weld W1 was formed on one of the four first blank joints 42.

[0106] In Comparative Example 2, the current collector 40 shown in Figure 5 was placed on the electrode assembly 10 and welded to the first blank joint 42 to form four linear first welds W1. That is, the current collector 40 in Figure 5 has four first blank joints 42 spaced approximately 90 degrees apart, and one first weld W1 was formed on each of the four first blank joints 42.

[0107] In Example 1, the current collector 40 shown in Figure 5 was placed on the electrode assembly 10 and welded to the first blank joint 42 to form four linear first welds W1 and four second welds W2. Specifically, the current collector 40 in Figure 5 has four first blank joints 42 spaced approximately 90 degrees apart, and four connection parts 44 spaced approximately 90 degrees apart. Here, one first weld W1 was formed on each of the four first blank joints 42, and one second weld W2 was formed on each of the four connection parts 44.

[0108] In other words, Experiment 2 was conducted to confirm the changes in resistance and standard deviation when the welding angle was changed. On the other hand, although the welding area was not set to be the same in Comparative Example 1, Comparative Example 2, and Example 1, as confirmed in Experiment 1, if a certain level of welding area is secured, the effect of increasing the welding area is minor, so it was judged that the effect of changing the welding area on the results in Experiment 2 would also be minor. The results of measuring the internal resistance (ACIR) of the batteries in Comparative Example 1, Comparative Example 2, and Example 1 are shown in Table 2 and the graph in Figure 12 below. For reference, the resistance values ​​shown in Table 2 and Figure 12 represent the resistance values ​​before activation.

[0109] [Table 2]

[0110] As is clear from Table 2 and Figure 12 above, in Example 1, the resistance value and standard deviation value decreased significantly due to the reduction of the welding angle to 45 degrees compared to Comparative Examples 1 and 2. Considering that the welding area affects the standard deviation but does not have a significant effect on the resistance value itself, Experiment 2 confirmed that the welding angle has a significant effect on the reduction of the resistance value. In particular, it was confirmed that when the angle of the weld (W) was 45 degrees or less, the internal resistance value of the battery decreased significantly to approximately 1.11 mΩ.

[0111] Referring again to Figure 7, the current collector 40 according to one embodiment of the present invention may be a current collector 40 applied to a cylindrical battery cell 1 which includes an electrode assembly 10 having a first blank portion 11 and a second blank portion 12, a battery can 20 that houses the electrode assembly 10 through an opening formed on one side and is electrically connected to the second blank portion 12, and a cell terminal 30 that is electrically connected to the first blank portion 11.

[0112] The current collector 40 is interposed between the closing portion of the battery can 20 located on the opposite side of the opening and the electrode assembly 10, and is bonded to one surface of the electrode assembly 10. It includes a peripheral portion 41 positioned on one surface of the electrode assembly 10, a first plain portion connecting portion 42 extending inward from the peripheral portion 41 and welded to the first plain portion 11, and a terminal connecting portion 43 positioned spaced apart from the first plain portion connecting portion 42 and welded to the cell terminal 30. A plurality of welds W are provided between the first plain portion 11 and the current collector 40, and the angle between adjacent welds W may be 45 degrees or less. Here, the welds W may include at least one of a first weld W1 and a second weld W2.

[0113] This structure significantly reduces the internal resistance of the battery. Furthermore, it minimizes process problems such as separator melting and / or welding splatter.

[0114] Figure 13 is a diagram showing a schematic configuration of a battery pack including a cylindrical battery cell according to an embodiment of the present invention.

[0115] Referring to Figure 13, a battery pack 3 according to one embodiment of the present invention includes a secondary battery assembly in which a plurality of cylindrical battery cells 1 according to one embodiment of the present invention described above are electrically connected, and a pack housing 2 that houses this assembly. In the drawings of the present invention, for illustrative purposes, components such as busbars for electrical connection, cooling units, and power terminals are omitted.

[0116] Figure 14 is a diagram showing a schematic configuration of an automobile including a battery pack according to an embodiment of the present invention.

[0117] Referring to Figure 14, the automobile 5 according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack 3 according to one embodiment of the present invention. The automobile 5 may include four-wheeled vehicles and two-wheeled vehicles. The automobile 5 operates by receiving power from the battery pack 3 according to one embodiment of the present invention.

[0118] Although the present invention has been described above based on limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and that various modifications and variations are possible within the equivalent scope of the technical idea of ​​the present invention and the appended claims by persons with ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0119] 5. Automobile 3 Battery Packs 2-pack housing 1. Cylindrical battery cell 10 Electrode assembly 11. First blank section 11a Split piece 12. Second blank section C Center of winding 20 Battery Cans 20a External surface (2nd electrode terminal) 30 Cell terminals (first electrode terminals) G2 Insulating Gasket 40 Current collector 41 Peripheral area 42. First plain section joining part 43 Terminal connection part 44 Connection part W Weld W1 First Weld W2 Second Weld

Claims

1. An electrode assembly comprising a first electrode, a second electrode, and a separator interposed between them, wound around a winding axis to define a core and an outer surface, wherein the first electrode has no active material layer coated on its long side end along the winding direction and includes a first blank portion exposed to the outside of the separator, and at least a portion of the first blank portion is used as an electrode tab, the electrode assembly, A battery can having an opening on one side and configured to house the electrode assembly through the opening, A cell terminal configured to penetrate the surface of the battery can located opposite to the opening, A current collector comprising a peripheral portion positioned on the upper part of the electrode assembly, a first plain portion connecting portion extending inward from the peripheral portion and welded to the first plain portion, and a terminal connecting portion positioned spaced apart from the first plain portion connecting portion and welded to the cell terminal, wherein a plurality of welds are provided between the first plain portion and the current collector, and the current collector is configured such that the angles between adjacent welds among the plurality of welds are acute angles, A cylindrical battery cell, including one.

2. The first blank portion connecting part and the terminal connecting part are, A cylindrical battery cell according to claim 1, electrically connected by the aforementioned peripheral portion.

3. The cylindrical battery cell according to claim 1 or 2, wherein the angles between adjacent welds among the plurality of welds are configured to be 45 degrees or less.

4. The cylindrical battery cell according to claim 1 or 2, wherein at least one first welded portion is provided between the first plain portion and the first plain portion joining portion.

5. The cylindrical battery cell according to claim 4, wherein the first welded portion is linear in shape along the extending direction of the first plain portion joint.

6. The aforementioned current collector is The cylindrical battery cell according to claim 4, further comprising a connecting portion extending inward from the peripheral portion and connected to the terminal connecting portion.

7. The cylindrical battery cell according to claim 6, wherein at least one second welded portion is provided between the first plain portion and the connecting portion.

8. The cylindrical battery cell according to claim 7, wherein the second welded portion is linear in shape along the extending direction of the connection portion.

9. The cylindrical battery cell according to claim 7, wherein the angle between adjacent welds among the first weld and the second weld is configured to be 45 degrees or less.

10. At least one of the first plain section joining portion and the connecting portion is A cylindrical battery cell according to claim 6, wherein multiple cells are provided.

11. The aforementioned connection part is A cylindrical battery cell according to claim 6, located between a pair of adjacent first plain portion connecting portions.

12. At least one of the first weld and the second weld is A cylindrical battery cell according to claim 7, wherein multiple cells are provided.

13. A cylindrical battery cell according to claim 1 or 2, A pack housing that accommodates a plurality of the cylindrical battery cells, Includes a battery pack.

14. An automobile comprising the battery pack described in claim 13.

15. A current collector applicable to a cylindrical battery cell, comprising an electrode assembly having a first blank portion and a second blank portion, a battery can housing the electrode assembly through an opening formed on one side and electrically connected to the second blank portion, and a cell terminal electrically connected to the first blank portion, Interposed between the closing portion of the battery can located on the opposite side of the opening and the electrode assembly, and coupled to one surface of the electrode assembly, A peripheral portion arranged on one surface of the electrode assembly, A first plain portion joining portion extends inward from the peripheral portion and is welded to the first plain portion, A terminal coupling portion is located spaced apart from the first plain portion coupling portion and is welded to the cell terminal, Includes, A current collector wherein a plurality of welded joints are provided between the first plain portion and the current collector, and the angle between adjacent welded joints is 45 degrees or less.

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