Cylindrical battery cell, current collector applied to cylindrical battery cell, and battery pack and vehicle comprising cylindrical battery cell

Abstract

A cylindrical battery cell according to one embodiment of the present invention comprises: an electrode assembly in which a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode are wound around a winding axis to define a core part and an outer peripheral surface, the first electrode includes a first uncoated portion that is not coated with the active material layer on an end portion of a long side in the winding direction and is exposed to the outside of the separator, and at least a portion of the first uncoated portion itself serves as an electrode tab; a battery can including an opening on one side and configured to accommodate the electrode assembly through the opening; a cell terminal configured to pass through a surface of the battery can on an opposite side of the opening; an edge portion disposed on an upper portion of the electrode assembly; a first uncoated portion coupling portion that extends inward from the edge portion and is welded and coupled to the first uncoated portion; and a terminal coupling portion spaced apart from the first uncoated portion coupling portion and welded and coupled to the cell terminal, in which a plurality of welding portions are provided between the first uncoated portion and the current collector, and an angle between adjacent welding portions among the plurality of welding portions is configured to be an acute angle.

Description

Technical Field

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

[0002] This application is based on and claims the benefit of priority from Korean Patent Application No. 10-2023-0137148 filed on October 13, 2023, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Background Art

[0003] Secondary batteries are used in various fields. For example, battery packs used in devices such as electric vehicles require high capacity and high output. Such high-capacity and high-output battery packs may include cylindrical battery cells as unit cells.

[0004] Cylindrical battery cells with high capacity and output can be configured so that electrode tabs are located across the entire area of ​​both sides of the winding core to improve current collection efficiency, and current collectors are connected to both sides of the winding core. This structure maximizes the contact area between the electrode tabs and the current collectors, thereby minimizing the resistance generated at the connection between the components.

[0005] Furthermore, factors that increase circuit resistance in secondary batteries include welds connecting the current collector and electrode assembly. The increased number of welds leads to process issues such as separator melting and / or weld spatter. Therefore, minimizing welds and electrical resistance is an important issue. Summary of the Invention

[0006] Technical issues

[0007] The present disclosure is intended to solve the problems of the prior art, and thus the present disclosure is intended to minimize the internal resistance of a secondary battery.

[0008] On the other hand, the present disclosure aims to minimize a weld portion of a secondary battery.

[0009] More specifically, the present disclosure is also directed to minimizing process issues such as diaphragm melting and / or weld spatter.

[0010] However, the technical problems that the present disclosure seeks to solve are not limited to the above problems, and those skilled in the art will clearly understand other problems not mentioned above from the description of the present invention described below.

[0011] Technical Solution

[0012] In one aspect of the present disclosure, a cylindrical battery cell is provided, the cylindrical battery cell comprising: an electrode assembly comprising a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, the first electrode, the second electrode, and the separator being wound around a winding axis to define a core portion and an outer surface, wherein the first electrode comprises a first uncoated region on a longitudinal end portion along the winding direction that is not coated with an active material layer and is exposed to the outside of the separator, and wherein at least a portion of the first uncoated region serves as an electrode tab; a battery can comprising an opening on one side and being configured to accommodate the electrode assembly through the opening ; a battery cell terminal configured to pass through a surface of the battery can on the opposite side of the opening; and a current collector comprising: an edge portion disposed at a top of the electrode assembly; a first uncoated area connecting portion extending inwardly from the edge portion and welded to the first uncoated area; and a terminal connecting portion spaced apart from the first uncoated area connecting portion and welded to the battery cell terminal, wherein a plurality of welds are disposed between the first uncoated area and the current collector, and wherein angles between adjacent welds among the plurality of welds are configured to be acute angles.

[0013] In one aspect of the present disclosure, the first uncoated region coupling portion and the terminal coupling portion may be electrically connected through an edge portion.

[0014] Preferably, an angle between adjacent welding portions among the plurality of welding portions may be configured to be 45 degrees or less.

[0015] In another aspect of the present disclosure, one or more first welding parts may be provided between the first uncoated region and the first uncoated region coupling portion.

[0016] For example, the first welding portion may have a linear shape along an extending direction of the first uncoated region coupling portion.

[0017] In another aspect of the present disclosure, the current collector may further include a connection portion extending inwardly from the edge portion and connected to the terminal coupling portion.

[0018] Here, one or more second welding portions may be provided between the first uncoated region and the connecting portion.

[0019] For example, the second welding portion may have a linear shape along the extending direction of the connecting portion.

[0020] Preferably, an angle between adjacent welds among the first welds and the second welds may be configured to be 45 degrees or less.

[0021] In another aspect of the present disclosure, at least one of the first uncoated region coupling portion and the connecting portion may be provided in plural.

[0022] In another aspect of the present disclosure, the connection portion may be located between a pair of first uncoated region coupling portions adjacent to each other.

[0023] In another aspect of the present disclosure, at least one of the first welding portion and the second welding portion may be provided in plural.

[0024] Furthermore, a battery pack according to an embodiment of the present disclosure may include the cylindrical battery cell according to the present disclosure, and a battery pack case configured to accommodate the plurality of cylindrical battery cells.

[0025] A vehicle according to an embodiment of the present disclosure may include the above-described battery pack according to the present disclosure.

[0026] In addition, a current collector applied to a cylindrical battery cell, the cylindrical battery cell including: an electrode assembly having a first uncoated area and a second uncoated area; a battery can configured to accommodate the electrode assembly through an opening formed on one side and electrically connected to the second uncoated area; and a battery terminal electrically connected to the first uncoated area, the current collector may include: an edge portion, the edge portion being inserted between a closed portion of the battery can positioned opposite to the opening and the electrode assembly, and being connected to a surface of the electrode assembly so as to be set on the electrode assembly; a first uncoated area connecting portion, the first uncoated area connecting portion extending inwardly from the edge portion and welded to the first uncoated area; and a terminal connecting portion, the terminal connecting portion being spaced apart from the first uncoated area connecting portion and welded to the battery terminal, wherein a plurality of welds are provided between the first uncoated area and the current collector, and wherein the angle between adjacent welds among the plurality of welds is configured to be 45 degrees or less.

[0027] Beneficial effects

[0028] According to one aspect of the present disclosure, the internal resistance of a secondary battery can be effectively reduced.

[0029] According to another aspect of the present disclosure, a weld portion of a secondary battery may be minimized.

[0030] Therefore, process problems such as diaphragm melting and / or weld spatter can be minimized.

[0031] However, effects obtainable according to 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 description of the present invention described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0033] Figure 1 is a diagram illustrating the appearance of a cylindrical battery cell according to an embodiment of the present disclosure.

[0034] Figure 2 is a cross-sectional view illustrating the internal structure of a cylindrical battery cell according to an embodiment of the present disclosure.

[0035] Figure 3 It shows Figure 1 Figure 1 shows the electrode assembly, cell terminals, and current collector included in a cylindrical battery cell.

[0036] Figure 4 is a diagram showing a weld between an electrode assembly and a current collector.

[0037] Figure 5 It shows Figure 1 Figure 2 shows a diagram of the current collector included in a cylindrical battery cell.

[0038] Figure 6 is a diagram illustrating a conventional configuration in which a current collector is welded to an electrode assembly.

[0039] Figure 7 is a diagram illustrating a configuration of welding a current collector to an electrode assembly according to an embodiment of the present disclosure.

[0040] Figure 8 is a diagram illustrating a configuration of welding a current collector to an electrode assembly according to another embodiment of the present disclosure.

[0041] Figure 9 is a diagram illustrating a configuration of welding a current collector to an electrode assembly according to another embodiment of the present disclosure.

[0042] Figure 10 is a diagram illustrating a configuration of welding a current collector to an electrode assembly according to another embodiment of the present disclosure.

[0043] Figure 11 is a graph showing internal resistances of a cylindrical battery cell according to an embodiment of the present disclosure and a battery cell according to a comparative example.

[0044] Figure 12 is a graph showing internal resistances of a cylindrical battery cell according to an embodiment of the present disclosure and a battery cell according to a comparative example.

[0045] Figure 13 is a diagram illustrating a schematic configuration of a battery pack including cylindrical battery cells according to an embodiment of the present disclosure.

[0046] Figure 14 is a diagram showing a schematic configuration of a vehicle including a battery pack according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] Hereinafter, 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 and dictionary meanings, but are interpreted according to the meanings and concepts 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 descriptions provided herein are only preferred examples for illustrative purposes and are not intended to limit the scope of the present disclosure. Therefore, it should be understood that other equivalents and modifications may be made thereto without departing from the scope of the present disclosure.

[0048] For the purpose of explanation and clarification, the sizes of some elements shown in the drawings may be exaggerated rather than reflecting their actual sizes. In addition, the same reference numerals may designate the same elements among the embodiments.

[0049] The expression "two components are identical" indicates that they are "substantially identical." Thus, substantially identical components may include components that are identical with a deviation that is considered low in the art (e.g., less than 5%). Additionally, uniformity of a parameter in a given area may indicate uniformity from an average perspective.

[0050] Figure 1 is a diagram showing the appearance of a cylindrical battery cell according to an embodiment of the present disclosure, Figure 2 is a cross-sectional view illustrating the internal structure of a cylindrical battery cell according to an embodiment of the present disclosure.

[0051] Reference Figure 1 and Figure 2 , a cylindrical battery cell 1 according to an embodiment of the present disclosure includes an electrode assembly 10 , a battery can 20 , a cell terminal 30 , and a current collector 40 .

[0052] In addition to the above components, the cylindrical battery cell 1 may further include an insulating gasket G2 and a second current collector.

[0053] 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 a positive electrode or a negative electrode, and the second electrode corresponds to an electrode having a polarity opposite to that of the first electrode.

[0054] The electrode assembly 10 may have, for example, a jellyroll structure. That is, the electrode assembly 10 may be manufactured by winding a laminate in one direction with a winding center C as a reference, the laminate being formed by stacking a first electrode current collector 40 and a second electrode current collector 40 in sheet form into one or more layers with a separator interposed therebetween. 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 jellyroll structure known in the art may be applied to the present disclosure without limitation.

[0055] 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. A first uncoated area 11 not coated with the first electrode active material is formed at one end of the first electrode current collector 40 in the width direction (parallel to the Z axis). Hereinafter, the first uncoated area 11 used as the first electrode connector will be referred to as the first uncoated area 11. The first uncoated area 11 is arranged at the top of the electrode assembly 10 housed in the battery can 20 in the height direction (parallel to the Z axis). That is, the first electrode current collector 40 includes a first uncoated area 11 on which the active material layer is not coated on its longitudinal end portion and is exposed to the outside of the diaphragm, and a portion of the first uncoated area 11 itself is used as an electrode connector. The first uncoated area 11 can be, for example, a positive electrode connector.

[0056] In addition, at least a portion of the first uncoated region 11 may include a plurality of segments divided in the winding direction of the electrode assembly 10. In this case, the plurality of segments may be bent in the radial direction of the electrode assembly 10. The plurality of bent segments may overlap each other in multiple layers. In this case, the coupling portion 32 of the first uncoated region 11, described later, may be coupled to the region where the plurality of segments overlap in multiple layers.

[0057] The second electrode includes a second electrode current collector 40 and a second electrode active material coated on one or both surfaces of the second electrode current collector 40. A first uncoated region 11 not coated with the second electrode active material is provided at the other end of the second electrode current collector 40 in the width direction (parallel to the Z-axis). Hereinafter, the first uncoated region 11 serving as the second electrode tab will be referred to as the second uncoated region 12. The second uncoated region 11 is provided at the bottom of the electrode assembly 10 housed in the battery can 20 in the height direction (parallel to the Z-axis). That is, the second electrode current collector 40 includes a second uncoated region 12 at its longitudinal end that is not coated with the active material layer and is exposed to the outside of the separator, and a portion of the second uncoated region 12 itself serves as an electrode tab. The second uncoated region 12 may be, for example, a positive electrode tab. In addition, at least a portion of the second uncoated region 12 may include a plurality of segments divided in the winding direction of the electrode assembly 10. In this case, the plurality of segments may be bent in the radial direction of the electrode assembly 10. The plurality of bent segments may overlap each other in multiple layers. In this case, the second current collector may be coupled to the region where the plurality of segments overlap in multiple layers.

[0058] The first uncoated region 11 and the second uncoated region 11 extend in opposite directions along the height direction (parallel to the Z axis) of the cylindrical battery cell 1. The first uncoated region 11 extends toward the closed portion of the battery can 20, and the second uncoated region 11 extends toward the opening of the battery can 20.

[0059] In the present disclosure, in terms of the positive electrode active material coated on the positive electrode plate and the negative electrode active material coated on the negative electrode, any active material known in the art may be used without limitation.

[0060] Figure 3 It shows Figure 1 FIG. 1 is a diagram of an electrode assembly 10, a cell terminal 30, and a current collector 40 included in a cylindrical battery cell.

[0061] Will refer to Figure 3 The structure of the electrode assembly 10 will be described in more detail. Hereinafter, the first electrode among the first and second electrodes will be described as an example, but the structure of the first electrode can be similarly applied to the second electrode.

[0062] Preferably, the first uncoated region 11 may include a plurality of grooved segments 11a. The plurality of segments 11a may form a plurality of groups, and the segments 11a in each group may have substantially the same height (length in the Z-axis direction), width (length in the X-axis direction), and / or spacing. The number of segments 11a in each group may be increased or decreased from that shown in the figure.

[0063] Uncoated regions 11 and 12 may be bent in the radial direction of electrode assembly 10, for example, from the periphery toward the core. When uncoated regions 11 and 12 are bent, segments adjacent to each other in the radial direction overlap each other in multiple layers, thereby forming curved surfaces at the top and bottom of electrode assembly 10.

[0064] The battery can 20 may be configured to include an opening on one side and accommodate the electrode assembly 10 through the opening.

[0065] Specifically, the battery can 20 is a roughly cylindrical container with an opening formed at the bottom, made of a conductive material such as metal. The material of the battery can 20 may include, for example, steel, stainless steel or nickel-plated steel. The upper surface located on the opposite side of the opening will be referred to as the closed portion. The side wall and the closed portion of the battery can 20 may be formed integrally. Alternatively, the side wall and the closed portion of the battery can 20 may be provided separately and then connected to each other by welding or the like. The upper surface (parallel to the XY plane) of the battery can 20 (that is, the outer surface 20a of the closed portion) may have a generally flat shape. The battery can 20 accommodates the electrode assembly 10 and the electrolyte together through the opening formed at the bottom.

[0066] The battery can 20 is electrically connected to the electrode assembly 10. For example, the battery can 20 is electrically connected to the second uncoated region 12 of the electrode assembly 10. In this case, the battery can 20 has the same polarity as the second uncoated region 12.

[0067] Figure 4 1 is a diagram illustrating a weld W between the electrode assembly 10 and the current collector 40 .

[0068] Reference Figures 1 to 4, the cell terminal 30 is made of a conductive metal material. The material of the cell terminal 30 may include, for example, aluminum (Al). If the cell terminal 30 is made of aluminum, riveting processing can be easily performed on it. The cell terminal 30 can be made of 10 series aluminum with relatively low resistance. The cell terminal 30 passes through the upper surface of the battery can 20 (that is, the surface located on the opposite side of the opening of the battery can 20 (parallel to the XY plane)). The cell terminal 30 is electrically connected to the first uncoated area 11 of the electrode assembly 10, for example. In this case, the cell terminal 30 has a first polarity. Therefore, the cell terminal 30 can be used as the first electrode terminal in the cylindrical battery cell 1 of the present disclosure. When the cell terminal 30 has a first polarity, the cell terminal 30 is electrically insulated from the battery can 20 having a second polarity. Electrical insulation between the cell terminal 30 and the battery can 20 can be achieved in various ways. For example, insulation can be achieved by inserting 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 portion of the cell terminal 30. Alternatively, to prevent the cell terminal 30 from contacting the battery can 20, the cell terminal 30 can be securely fixed. Alternatively, two or more of the above methods can be applied together. The cell terminal 30 can be riveted to the closed portion of the battery can 20.

[0069] Reference Figure 2 and Figure 3 , the bottom surface of the central region of the cell terminal 30 and the current collector 40 may be coupled by, for example, laser welding, spot welding, or ultrasonic welding.

[0070] Welding can be performed by irradiating a laser beam 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, thereby forming a weld bead on one side of the current collector 40 (facing the hole formed in the winding center C of the electrode assembly 10).

[0071] According to this structure, the cylindrical battery cell 1 according to an embodiment of the present disclosure can ensure smooth current flow at the connection portion of the current collector 40 and the cell terminal 30 when a large amount of current flows due to rapid charging, thereby producing effects such as shortening the charging time and reducing heat generation.

[0072] An insulating gasket G2 may be interposed between the outer surface 20a of the sealed portion of the battery can 20 and the cell terminals 30. The insulating gasket G2 may be made of, for example, an insulating and elastic resin material. Thus, the insulating gasket G2 may electrically insulate the battery can 20 from the cell terminals 30.

[0073] Reference Figures 3 to 5, the current collector 40 is coupled to the top of the electrode assembly 10. The current collector 40 is made of a conductive metal material and is connected to the first uncoated region 11. More specifically, the current collector 40 may be welded to the top of the electrode assembly 10.

[0074] The current collector 40 can be welded to a coupling surface (curved surface) formed by bending the end of the first uncoated region 11 in a direction parallel to the current collector 40. The bending direction of the first uncoated region 11 can be the radial direction of the electrode assembly 10. The bending direction of the first uncoated region 11 can be, for example, a direction toward the winding center C of the electrode assembly 10. When the first uncoated region 11 is configured into the above-mentioned curved shape, the space occupied by the first uncoated region 11 can be reduced, thereby improving the energy density. In addition, the increase in the bonding area between the first uncoated region 11 and the current collector 40 can lead to an increase in bonding strength and a reduction in contact resistance.

[0075] Reference Figures 3 to 5 , at least a portion of the first uncoated region 11 and / or the second uncoated region 12 may include a plurality of segments 11a divided along the winding direction of the electrode assembly 10. In this case, the plurality of segments may be bent along the radial direction of the electrode assembly 10. The plurality of bent segments may overlap each other in multiple layers. In this case, the first uncoated region coupling portion 42 of the current collector 40 described later may be coupled to the region where the plurality of segments overlap each other in multiple layers.

[0076] The current collector 40 electrically connects the first uncoated region 11 of the electrode assembly 10 and the cell terminal 30. The first current collector 40 is made of a conductive metal material.

[0077] Reference Figure 5 The current collector 40 includes an edge portion 41, a first uncoated region coupling portion 42, and a terminal coupling portion 43. The edge portion 41 may be disposed on top of the electrode assembly 10 and may have a substantially edge shape with an empty space S formed therein. Although the edge portion 41 is illustrated as a substantially circular edge in the drawings of the present disclosure, the present disclosure is not limited thereto.

[0078] The first uncoated area coupling portion 42 extends inward from the edge portion 41 and is coupled to the first uncoated area 11. Preferably, the first uncoated area coupling portion 42 extends inward from the edge portion 41 and is welded to the first uncoated area 11. In this case, a weld W may be provided between the first uncoated area coupling portion 42 and the first uncoated area 11.

[0079] Preferably, the connection between the current collector 40 and the first uncoated region 11 is performed so as to overlap with the welding target region by at least about 50%, which is a section where the number of overlapping layers of the segment is substantially the largest and maintained at a constant level. That is, the first uncoated region connecting portion 42 of the current collector 40 can be connected to the first uncoated region 11 in a manner that overlaps with the welding target region by at least about 50%.

[0080] The terminal connection portion 43 is located inside the edge portion 41 and is separated from the first uncoated region connection portion 42. The terminal connection portion 43 can also be connected to the cell terminal 30 by welding. The diameter of the terminal connection portion 43 can be approximately the same as or larger than the diameter of the flat portion formed on the bottom surface of the cell terminal 30 to ensure a sufficient welding area for connection with the flat portion formed on the bottom surface of the cell terminal 30.

[0081] In one aspect of the present disclosure, a plurality of welds W may be provided between the first uncoated region 11 and the current collector 40, and adjacent welds W among the plurality of welds W may be configured to have an acute angle therebetween. The welds W may include at least one of a first weld W1 and a second weld W2, described later.

[0082] Figure 6 is a diagram showing a conventional configuration in which a current collector 40 is welded to an electrode assembly 10, Figure 7 is a diagram illustrating a configuration in which a current collector 40 is welded to an electrode assembly 10 according to an embodiment of the present disclosure.

[0083] For example, refer to Figure 6 In the conventional current collector 40, adjacent weld portions W are configured to have an angle of about 90 degrees. However, if the angle between adjacent weld portions W is about 90 degrees or more, the internal resistance of the battery increases.

[0084] In addition, referring to the embodiment according to the present disclosure Figure 7 , a plurality of welding portions W are provided between the current collector 40 and the electrode assembly 10, and the angles between adjacent welding portions W are configured to be acute angles. More specifically, Figure 2 In the embodiment, the angle between adjacent welds W is configured to be approximately 45 degrees. As described above, since the angles between adjacent welds W among the plurality of welds W provided between the first uncoated region 11 and the current collector 40 are configured to be acute, the internal resistance (ACIR) of the battery can be effectively reduced. In addition, this structure can minimize process issues such as separator melting and / or weld spatter.

[0085] The first uncoated region coupling portion 42 and the terminal coupling portion 43 may be spaced apart from each other instead of being directly connected. The first uncoated region coupling portion 42 and the terminal coupling portion 43 are electrically connected via the edge portion 41. As described above, the current collector 40 according to the embodiment of the present disclosure has a structure in which the first uncoated region coupling portion 42 and the terminal coupling portion 43 are not directly coupled to each other but are coupled via the edge portion 41, so that when an impact and / or vibration occurs in the cylindrical battery cell 1, the impact applied to the coupling portion between the first uncoated region coupling portion 42 and the first uncoated region 11 and the coupling portion between the terminal coupling portion 43 and the cell terminal 30 can be dispersed. Therefore, the current collector 40 of the present disclosure can minimize or prevent damage to the weld W due to external impact.

[0086] Figure 7 is a diagram illustrating a configuration of welding a current collector 40 to an electrode assembly 10 according to an embodiment of the present disclosure, Figure 8 is a diagram illustrating a configuration of welding a current collector 40 to an electrode assembly 10 according to another embodiment of the present disclosure.

[0087] Preferably, an angle between adjacent weld portions W among the plurality of weld portions W may be configured to be about 45 degrees or less.

[0088] For example, refer to Figure 7 and Figure 8 , the angle between adjacent welds W is configured to be about 45 degrees. With this structure, the internal resistance of the battery can be significantly reduced compared to a conventional cylindrical battery cell in which the angle between adjacent welds W is about 90 degrees. In addition, according to this structure, process problems such as melting of the separator and / or weld spatter can be minimized. However, if the angle between adjacent welds W is set too small, the time or cost required for the process may increase, which may reduce productivity. This will be referred to later. Figure 11 and Figure 12 The experimental curve graph in the figure describes the specific effects and values ​​in detail.

[0089] The current collector 40 may further include a connection portion 44 extending inward from the edge portion 41 and connected to the terminal coupling portion 43 .

[0090] The connecting portion 44 may include a tapered portion 44a whose width decreases from the inner surface of the edge portion 41 toward the terminal connection portion 43. That is, the tapered portion 44a may be configured so that its width increases from the connection between the terminal connection portion 43 and the edge portion 41 toward the edge portion 41. The width of the tapered portion 44a may vary continuously or in steps. Providing the tapered portion 44a improves component rigidity at the connection between the connecting portion 44 and the edge portion 41. Providing the tapered portion 44a allows, for example, transport equipment and / or workers to maintain contact with the tapered portion 44a during the manufacturing process of the cylindrical battery cell 1, thereby easily and safely transporting the current collector 40 and / or the combination of the current collector 40 and the electrode assembly 10. In other words, providing the tapered portion 44a prevents product defects caused by maintaining welds to other parts, such as the first uncoated region connecting portion 42 or the terminal connection portion 43.

[0091] In addition, multiple first uncoated area connecting portions 42 may be provided. When multiple first uncoated area connecting portions 42 are provided, the multiple first uncoated area connecting portions 42 may, for example, be arranged radially around the center of the terminal connecting portion 43. Although the drawings of the present disclosure only illustrate cases where the number of first uncoated area connecting portions 42 is 3, 4, or 6, the present disclosure is not limited thereto. The number of first uncoated area connecting portions 42 may be determined in various ways, taking into account the resistance level required for the cylindrical battery cell 1, the aperture ratio of the first current collector 40, and the like. The multiple first uncoated area connecting portions 42 may also be regularly arranged along the extension direction of the edge portion 41. For example, the multiple first uncoated area connecting portions 42 may be arranged at substantially the same intervals along the extension direction of the edge portion 41. The multiple first uncoated area connecting portions 42 may have substantially the same extension length. The first uncoated area connecting portions 42 may be connected to the first uncoated region 11 by welding.

[0092] The terminal connection portion 43 may be provided to be surrounded by a plurality of first uncoated region connection portions 42. The terminal connection portion 43 may be connected to the cell terminal 30 by welding. The connection portion 44 may be located between a pair of first uncoated region connection portions 42 adjacent to each other. In this case, the distance from the connection portion 44 along the extension direction of the edge portion 41 to one of the pair of first uncoated region connection portions 42 may be approximately the same as the distance from the connection portion 44 along the extension direction of the edge portion 41 to the other of the pair of first uncoated region connection portions 42. The plurality of first uncoated region connection portions 42 may also be formed to have approximately the same cross-sectional area. The plurality of first uncoated region connection portions 42 may be formed to have substantially the same width and thickness.

[0093] A plurality of connection portions 44 may be provided. The number of connection portions 44 may be determined in consideration of the resistance level required for the cylindrical battery cell 1, the aperture ratio of the first current collector 40, and the like. Each of the plurality of connection portions 44 may be provided between a pair of first uncoated region coupling portions 42 adjacent to each other. The plurality of connection portions 44 may be regularly arranged in the extension direction of the edge portion 41. For example, the plurality of connection portions 44 may be arranged at substantially the same intervals along the extension direction of the edge portion 41. In addition, the distance from each of the plurality of connection portions 44 to one of the pair of first uncoated region coupling portions 42 adjacent to each other along the extension direction of the edge portion 41 may be substantially the same as the distance to the remaining first uncoated region coupling portions 42.

[0094] As described above, in the case where a plurality of first uncoated area connecting portions 42 and / or a plurality of connecting portions 44 are provided, if the distance between the first uncoated area connecting portions 42, the distance between the connecting portions 44 and / or the distance between the first uncoated area connecting portions 42 and the connecting portions 44 are formed to be approximately constant, a current can be smoothly formed from the first uncoated area connecting portions 42 to the connecting portions 44 or from the connecting portions 44 to the first uncoated area connecting portions 42.

[0095] The current collector 40 may be coupled to the first uncoated region 11 by welding. In this case, for example, laser welding, ultrasonic welding, or spot welding may be applied.

[0096] As one embodiment of the present disclosure, at least one first welding portion W1 may be provided between the first uncoated region 11 and the coupling portion of the first uncoated region 11. Preferably, the first welding portion W1 may be configured to have a linear shape along an extending direction of the coupling portion of the first uncoated region 11.

[0097] For example, refer to Figure 7 , a first welding portion W1 is provided in a linear shape between the first uncoated area 11 and the connecting portion of the first uncoated area 11. However, the embodiments of the present disclosure are not limited to linear shapes. For example, for the convenience of welding, an elliptical shape or a zigzag shape may be included within the scope of the present disclosure. Since the first welding portion W1 is formed on the connecting portion of the first uncoated area 11 extending in the radial direction, the first welding portion W1 may also be a shape extending in the radial direction. That is, if the first welding portion W1 has, for example, an elliptical shape, the elliptical shape may extend in the radial direction. For example, if the first welding portion W1 has a zigzag shape, it may have a zigzag shape extending in the radial direction.

[0098] As another embodiment of the present disclosure, at least one second weld portion W2 may be provided between the first uncoated region 11 and the connecting portion 44. Preferably, the second weld portion W2 may be configured to have a linear shape along the extending direction of the coupling portion of the first uncoated region 11.

[0099] For example, refer to Figure 7 , at least one second welding portion W2 is provided between the first uncoated area 11 and the connecting portion 44. However, the embodiments of the present disclosure are not limited to linear forms. For example, for the convenience of welding, an elliptical shape or a zigzag shape may be included in the scope of the present disclosure. Since the second welding portion W2 is formed on the connecting portion 44 extending in the radial direction, the second welding portion W2 may also be a shape extending in the radial direction. That is, if the second welding portion W2 has, for example, an elliptical shape, the elliptical shape may extend in the radial direction. For example, if the second welding portion W2 has a zigzag shape, it may have a zigzag shape extending in the radial direction.

[0100] In another embodiment of the present disclosure, at least one of the first welding portion W1 and the second welding portion W2 may be provided in plural.

[0101] For example, refer to Figure 7 , a plurality of first welding portions W1 and a plurality of second welding portions W2 may be provided. In addition, although not shown, only the first welding portion W1 may be provided in plurality, or only the second welding portion W2 may be provided in plurality.

[0102] According to the structure in which at least one of the first welding portion W1 and the second welding portion W2 is provided in a plurality, the welding area is increased, thereby reducing the internal resistance of the battery. In addition, according to this structure, the angle between adjacent welding portions W can also be reduced. Therefore, process problems such as melting of the separator and / or welding spatter can be minimized. Figure 11 and Figure 12 The experimental curve graph in the figure describes the specific effects and values ​​in detail.

[0103] As one embodiment of the present disclosure, refer to Figure 7 , adjacent welds W among the first welds W1 and the second welds W2 may be configured to have an acute angle therebetween. Preferably, the angle between adjacent welds W among the first welds W1 and the second welds W2 may be configured to be 45 degrees or less.

[0104] As another embodiment of the present disclosure, refer to Figure 8 , the first uncoated region 11 coupling portion may be configured to be directly connected to the terminal coupling portion 43. That is, in this case, the first uncoated region 11 coupling portion itself may become the connecting portion 44. Figure 8 In the illustrated embodiment, the first uncoated region 11 coupling portion may become the connection portion 44, and a weld W may be provided in all the connection portions between the edge portion 41 and the terminal coupling portion 43. In this case, the angle between adjacent welds W may be, for example, about 45 degrees or less.

[0105] Figure 9 is a diagram illustrating a configuration of welding a current collector 40 to an electrode assembly 10 according to another embodiment of the present disclosure.

[0106] As another embodiment of the present disclosure, an angle between adjacent weld portions W among the plurality of weld portions W may be configured to be 60 degrees or less.

[0107] For example, refer to Figure 9 , three first uncoated region 11 coupling portions may be arranged at intervals of approximately 120 degrees. Additionally, three connecting portions 44 may be arranged at intervals of approximately 120 degrees. Here, the first uncoated region 11 coupling portions and the connecting portions 44 may be alternately arranged. In this case, the first weld W1 provided in the first uncoated region 11 coupling portion and the second weld W2 provided in the adjacent connecting portion 44 may be configured to be arranged at intervals of approximately 60 degrees therebetween.

[0108] This structure can reduce the internal resistance of the battery and minimize process problems such as separator melting and / or weld spatter.

[0109] Figure 10 is a diagram illustrating a configuration of welding a current collector 40 to an electrode assembly 10 according to another embodiment of the present disclosure.

[0110] As another embodiment of the present disclosure, an angle between adjacent weld portions W among the plurality of weld portions W may be configured to be 30 degrees or less.

[0111] For example, refer to Figure 10 , six first uncoated region 11 coupling portions may be arranged at intervals of approximately 60 degrees. Additionally, six connection portions 44 may be arranged at intervals of approximately 60 degrees. Here, the first uncoated region 11 coupling portions and the connection portions 44 may be alternately arranged. In this case, the first weld W1 provided in the first uncoated region 11 coupling portion and the second weld W2 provided in the adjacent connection portion 44 may be arranged at intervals of approximately 30 degrees.

[0112] This structure can further reduce the internal resistance of the battery and further minimize process problems such as separator melting and / or weld spatter.

[0113] Below, we will refer to Figure 11 and Figure 12 Changes in the internal resistance of the battery according to changes in the welding area and changes in the internal resistance of the battery according to changes in the welding angle are described.

[0114] <Experiment 1>

[0115] Figure 11 is a graph showing internal resistances of a cylindrical battery cell according to an embodiment of the present disclosure and a battery cell according to a comparative example.

[0116] Figure 11 The experiment in Figure 5 The current collector 40 shown in FIG is welded to the electrode assembly 10 in the 4695 battery cell. Figure 5 The current collector 40 is placed on the electrode assembly 10 and then welded at the connection portion of the first uncoated region 11, thereby forming four linear first welding portions W1. That is, Figure 5 The current collector 40 has four first uncoated region 11 coupling portions spaced about 90 degrees apart, and one first welding portion W1 is formed on each of the four first uncoated region 11 coupling portions.

[0117] In Experimental Example 2, Figure 5 The current collector 40 is placed on the electrode assembly 10, and then welded at the connection portion of the first uncoated region 11, thereby forming 8 linear first welds W1. That is, Figure 5 The current collector 40 has four first uncoated region 11 connecting portions spaced approximately 90 degrees apart, with two first welds W1 formed in each of the four first uncoated region 11 connecting portions. Thus, the positions of the first welds W1 in Experimental Example 2 are the same as those in Experimental Example 1, and the area of ​​the first welds W1 in Experimental Example 2 is twice that of the first welds W1 in Experimental Example 1.

[0118] That is, in Experiment 1, the changes in resistance value and standard deviation value were measured when only the welding area was changed under the same welding angle condition. Figure 11 The graph in FIG shows the measurement results of the internal resistance ACIR of the batteries in Experimental Example 1 and Experimental Example 2. For reference, Tables 1 and Figure 11 The resistance values ​​shown indicate the resistance values ​​before activation.

[0119] [Table 1]

[0120]

[0121] From the above table 1 and Figure 11It can be seen that when the welding area doubles from Experimental Example 1 to Experimental Example 2, the standard deviation decreases significantly from 0.0768 to 0.0193. On the other hand, it can be seen that even when the welding area doubles from Experimental Example 1 to Experimental Example 2, the resistance value does not change significantly. Specifically, compared with Experimental Example 1, the welding area in Experimental Example 2 increases to about 2 times, but the resistance becomes slightly higher. This is estimated to be a value that falls within the range of measurement error and is not due to the influence of the area. That is, based on the results of Experiment 1, it is confirmed that Figure 5 In the case of the current collector 40, if the welding area is maintained at a certain level of 4 lines, further increasing the welding area will not significantly affect the resistance value. In addition, Experiment 1 confirmed that increasing the welding area significantly reduces the standard deviation of the resistance.

[0122] Experiment 2

[0123] Figure 12 is a graph showing internal resistances of a cylindrical battery cell according to an embodiment of the present disclosure and a battery cell according to a comparative example.

[0124] Figure 12 The experiment was conducted by Figure 5 The current collector 40 shown in FIG is welded to the electrode assembly 10 in the 4680 battery cell. Figure 5 The current collector 40 is placed on the electrode assembly 10 and then welded at the connection portion of the first uncoated region 11, thereby forming a linear first weld portion W1. That is, Figure 5 The current collector 40 has four first uncoated region 11 coupling portions spaced about 90 degrees apart, and a first welding portion W1 is formed on one of the four first uncoated region 11 coupling portions.

[0125] In Comparative Example 2, Figure 5 The current collector 40 is placed on the electrode assembly 10 and then welded at the connection portion of the first uncoated region 11, thereby forming four linear first welding portions W1. That is, Figure 5 The current collector 40 has four first uncoated region 11 coupling portions spaced about 90 degrees apart, and one first welding portion W1 is formed in each of the four first uncoated region 11 coupling portions.

[0126] In implementation mode 1, Figure 5 The current collector 40 is placed on the electrode assembly 10 and then welded at the connection portion of the first uncoated region 11, thereby forming four linear first welds W1 and four linear second welds W2. That is, Figure 5The current collector 40 has four first uncoated region 11 coupling portions arranged at intervals of approximately 90 degrees and four connecting portions 44 arranged at intervals of approximately 90 degrees. Here, a first welding portion W1 is formed in each of the four first uncoated region 11 coupling portions, and a second welding portion W2 is formed in each of the four connecting portions 44.

[0127] That is, Experiment 2 aimed to determine the changes in resistance and standard deviation when the welding angle was changed. In addition, although the welding area was not set the same in Comparative Examples 1 and 2 and Embodiment 1, as confirmed in Experiment 1, if the welding area is ensured to a certain extent, the effect of increasing the welding area is extremely small. Therefore, in Experiment 2, it was confirmed that the change in welding area has little effect on the results. Figure 12 The graph of FIG1 shows the measurement results of the internal resistance ACIR of the batteries of Comparative Example 1, Comparative Example 2 and Embodiment 1. For reference, Table 2 and Figure 12 The resistance values ​​shown indicate the resistance values ​​before activation.

[0128] [Table 2]

[0129]

[0130] From Table 2 and Figure 12 It can be seen that, compared to Comparative Examples 1 and 2, when the weld angle was reduced to 45 degrees in Embodiment 1, the resistance value and standard deviation value were significantly reduced. Considering that the weld area affects the standard deviation but has no significant effect on the resistance value, Experiment 2 confirmed that the weld angle has a significant effect on reducing 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 was significantly reduced to approximately 1.11 mohm.

[0131] Return to reference Figure 7 , a current collector 40 according to an embodiment of the present disclosure can be applied to a cylindrical battery cell 1, which includes: an electrode assembly 10, the electrode assembly 10 having a first uncoated area 11 and a second uncoated area 12; a battery can 20, the battery can 20 accommodating the electrode assembly 10 through an opening formed on one side and electrically connected to the second uncoated area 12; and a battery terminal 30, the battery terminal 30 being electrically connected to the first uncoated area 11.

[0132] The current collector 40 may include: an edge portion 41 interposed between the closed portion of the battery can 20, located opposite the opening, and the electrode assembly 10 so as to be coupled to one surface of the electrode assembly 10 and disposed on one surface of the electrode assembly 10; a first uncoated region coupling portion 42 extending inwardly from the edge portion 41 and welded to the first uncoated region 11; and a terminal coupling portion 43 spaced apart from the first uncoated region 11 coupling portion and welded to the cell terminal 30. A plurality of welds W may be provided between the first uncoated region 11 and the current collector 40, and an angle between adjacent welds W among the plurality of welds W may be configured to be 45 degrees or less. Here, the welds W may include at least one of a first weld W1 and a second weld W2.

[0133] This structure significantly reduces the internal resistance of the battery and minimizes process problems such as separator melting and / or weld spatter.

[0134] Figure 13 is a diagram illustrating a schematic configuration of a battery pack including cylindrical battery cells according to an embodiment of the present disclosure.

[0135] Reference Figure 13 A battery pack 3 according to an embodiment of the present disclosure includes a secondary battery assembly in which a plurality of cylindrical battery cells 1 according to an embodiment of the present disclosure are electrically connected, and a battery pack case 2 that accommodates the secondary battery assembly. In the drawings of the present disclosure, components such as bus bars, cooling units, and power terminals for electrical connection are omitted for ease of drawing.

[0136] Figure 14 is a diagram showing a schematic configuration of a vehicle including a battery pack according to an embodiment of the present disclosure.

[0137] Reference Figure 14 The vehicle 5 according to the embodiment of the present disclosure may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes the battery pack 3 according to the embodiment of the present disclosure. The vehicle 5 includes a four-wheeled vehicle and a two-wheeled vehicle. The vehicle 5 is operated by the power supplied from the battery pack 3 according to the embodiment of the present disclosure.

[0138] 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 various modifications and variations can be made by those skilled in the art within the technical concept of the present disclosure and the equivalent scope of the claims described below.

[0139] [Explanation of Reference Numerals]

[0140] 5: Vehicle

[0141] 3: Battery pack

[0142] 2: Battery pack housing

[0143] 1: Cylindrical battery cell

[0144] 10: Electrode assembly

[0145] 11: First uncoated area

[0146] 11a: Segmentation

[0147] 12: Second uncoated area

[0148] C: Winding center

[0149] 20: Battery Can

[0150] 20a: Outer surface (second electrode terminal)

[0151] 30: Cell terminal (first electrode terminal)

[0152] G2: Insulation washer

[0153] 40: Current collector

[0154] 41: Edge

[0155] 42: First uncoated area connecting portion

[0156] 43: Terminal connection part

[0157] 44: Connection part

[0158] W: welding part

[0159] W1: First welding section

[0160] W2: Second welding part

Claims

1. A cylindrical battery cell, comprising: an electrode assembly comprising a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode, the first electrode, the second electrode, and the separator being wound around a winding axis to define a core and an outer surface, wherein the first electrode includes a first uncoated region on a longitudinal end portion along the winding direction that is not coated with an active material layer and is exposed to the outside of the separator, and wherein at least a portion of the first uncoated region serves as an electrode tab; a battery can including an opening on one side and configured to accommodate the electrode assembly through the opening; a cell terminal configured to pass through a surface of the battery can on an opposite side of the opening; and A current collector, the current collector comprising: an edge portion, the edge portion being arranged at the top of the electrode assembly; a first uncoated area connecting portion, the first uncoated area connecting portion extending inwardly from the edge portion and welded to the first uncoated area; and a terminal connecting portion, the terminal connecting portion being spaced apart from the first uncoated area connecting portion and welded to the battery cell terminal, wherein a plurality of welding portions are provided between the first uncoated area and the current collector, and wherein angles between adjacent welding portions among the plurality of welding portions are configured to be acute angles.

2. The cylindrical battery cell according to claim 1, in, The first uncoated region coupling portion and the terminal coupling portion are electrically connected through the edge portion.

3. The cylindrical battery cell according to claim 1, in, The angle between adjacent weld portions among the plurality of weld portions is configured to be 45 degrees or less.

4. The cylindrical battery cell according to claim 1, in, One or more first welding portions are provided between the first uncoated region and the first uncoated region coupling portion.

5. The cylindrical battery cell according to claim 4, in, The first welding portion has a linear shape along an extending direction of the first uncoated region coupling portion.

6. The cylindrical battery cell according to claim 4, in, The current collector further includes a connection portion extending inwardly from the edge portion and connected to the terminal coupling portion.

7. The cylindrical battery cell according to claim 6, in, One or more second welding portions are provided between the first uncoated area and the connecting portion.

8. The cylindrical battery cell according to claim 7, in, The second welding portion has a linear shape along an extending direction of the connecting portion.

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

10. The cylindrical battery cell according to claim 1, in, At least one of the first uncoated region coupling portion and the connecting portion is provided in plural.

11. The cylindrical battery cell according to claim 6, in, The connecting portion is located between a pair of first uncoated region coupling portions adjacent to each other.

12. The cylindrical battery cell according to claim 7, in, At least one of the first welding portion and the second welding portion is provided in plural.

13. A battery pack, comprising: The cylindrical battery cell according to any one of claims 1 to 12; as well as A battery pack housing is configured to accommodate a plurality of the cylindrical battery cells.

14. A vehicle comprising the battery pack according to claim 13.

15. A current collector for a cylindrical battery cell, the cylindrical battery cell comprising: an electrode assembly having a first uncoated region and a second uncoated region; a battery can configured to accommodate the electrode assembly through an opening formed on one side and electrically connected to the second uncoated region; and a cell terminal electrically connected to the first uncoated area, the current collector comprising: an edge portion interposed between a closing portion of the battery can located opposite to the opening and the electrode assembly and coupled to one surface of the electrode assembly so as to be disposed on the electrode assembly; a first uncoated area coupling portion extending inwardly from the edge portion and welded to the first uncoated area; and a terminal coupling portion spaced apart from the first uncoated region coupling portion and welded to the cell terminal, A plurality of welding portions are provided between the first uncoated region and the current collector, and an angle between adjacent welding portions among the plurality of welding portions is configured to be 45 degrees or less.

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