Cylindrical lithium secondary battery

Abstract

A cylindrical lithium secondary battery of the present invention comprises: a battery can which accommodates an electrode assembly through an opening part formed on one side thereof; a cap plate for covering the opening part; and a current collecting plate disposed between the electrode assembly and the cap plate and electrically connecting the electrode assembly and the battery can, wherein the tensile strength of the current collecting plate has a value of 200 N / mm2 to 370 N / mm2.

Description

Cylindrical lithium secondary battery [Cross-reference with related applications] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0190267, filed December 22, 2023, and Korean Patent Application No. 10-2024-0096753, filed July 22, 2024, the entire contents of which are incorporated herein by reference. [Technical Field] The present invention relates to a cylindrical lithium secondary battery. Recently, with the development of electric vehicle technology, the demand for high-capacity batteries has increased, and thus the development of large-volume, large-sized cylindrical batteries is required. In the case of small-sized cylindrical batteries that were commonly used in the past, that is, cylindrical batteries with form factors of 1865 or 2170, resistance or heat generation did not have a serious effect on battery performance because the capacity was small. However, if the specifications of the conventional small-sized cylindrical batteries are directly applied to large-sized cylindrical batteries, serious problems may occur in battery safety. As the size of the battery increases, the amount of heat and gas generated inside the battery also increases. This heat and gas may cause the temperature and pressure inside the battery to rise, which may cause the battery to ignite or explode. To prevent this, the heat and gas inside the battery must be appropriately discharged to the outside. To this end, the cross-sectional area of ​​the battery, which acts as a passage for dissipating heat outside the battery, must increase in proportion to the increase in volume. However, since the increase in cross-sectional area is usually less than the increase in volume, as the battery becomes larger, the amount of heat generated inside the battery increases, which may increase the risk of explosion and cause problems such as reduced output. In addition, when rapid charging is performed at high voltage, the battery may ignite due to the generation of a large amount of heat around the electrode tabs in a short period of time. In order to prevent such risks of fire or explosion, safety devices are provided in the secondary battery according to the prior art. For example, a safety vent mainly installed in a cylindrical secondary battery can be mentioned. According to the prior art, when the internal pressure of the secondary battery increases, a path is formed through which gas is discharged when a part of the safety vent is ruptured, and the gas inside the secondary battery is discharged to the outside through this path, thereby preventing the risk of explosion. However, even when such a safety vent operates, if the flame continues without the electrode assembly being discharged outside the can, a problem occurs in which the flame is ejected to the side of the can. When a cylindrical lithium secondary battery is used in an automobile, it is applied in the form of a battery pack in which several cylindrical lithium secondary batteries are combined, and there is a problem in that such a rupture of the side of the battery can causes flames to continuously occur in other surrounding unit cells. The cylindrical lithium secondary battery of the present invention can provide a cylindrical battery having a large volume so as to realize high capacity, while also improving the problem of the side of the can being ruptured when a flame occurs, thereby providing a cylindrical battery having high safety. [1] The present invention comprises a battery can that accommodates the electrode assembly through an opening formed on one side; a cap plate that covers the opening; and a current collector plate that is disposed between the electrode assembly and the cap plate and electrically connects the electrode assembly and the battery can, wherein the tensile strength of the current collector plate is 200 N / mm. 2 Up to 370 N / mm 2 A cylindrical lithium secondary battery is provided. [2] The present invention can provide a cylindrical lithium secondary battery in which, in the above [1], the battery can includes a beading portion which is a support portion on which the cap plate is fixed, and the current collecting plate is connected to the beading portion. [3] The present invention is characterized in that the tensile strength of the current collector plate is 230 N / mm in the above [1] or [2]. 2 Up to 350 N / mm 2 A cylindrical lithium secondary battery can be provided. [4] The present invention can provide a cylindrical lithium secondary battery having a thickness of 150 ㎛ to 300 ㎛, wherein the current collector plate is in any one of the above [1] to [3]. [5] The present invention can provide a cylindrical lithium secondary battery having a thickness of the beading portion of 0.4 mm to 0.6 mm in any one of the above [1] to [4]. [6] The present invention is a cylindrical lithium secondary battery according to any one of the above [1] to [5], wherein the current collector plate is a negative current collector plate. [7] The present invention can provide a cylindrical lithium secondary battery in which the current collecting plate is a copper thin film according to the above [6]. [8] The present invention can provide a cylindrical lithium secondary battery having a tab-less structure in which the positive electrode and the negative electrode each include a non-conductive portion on which an active material layer is not formed, and at least a part of the non-conductive portion of the positive electrode or the non-conductive portion of the negative electrode defines an electrode tab, in any one of the above [1] to [7]. [9] The present invention can provide a cylindrical lithium secondary battery according to the above [8], wherein the positive electrode non-coated portion and the negative electrode non-coated portion are formed along the direction in which the electrode assembly is wound on one end of each of the positive and negative electrodes, and a current collector plate is coupled to each of the positive electrode non-coated portion and the negative electrode non-coated portion, and the current collector plate is connected to an electrode terminal.

[0010] The present invention can provide a cylindrical lithium secondary battery in which, in the above [8] or [9], the positive and negative electrode non-conductive parts are processed into a plurality of independently foldable segments, and at least some of the plurality of segments are folded toward the winding center of the electrode assembly.

[0011] The present invention can provide a cylindrical lithium secondary battery in which, in the above

[0010] , at least some of the plurality of folded segments overlap on the upper and lower sides of the electrode assembly, and the current collector is bonded on the plurality of overlapped segments.

[0012] The present invention can provide a cylindrical lithium secondary battery having a form factor ratio of 0.4 or more in any one of the above [1] to

[0011] .

[0013] The present invention can provide a cylindrical lithium secondary battery having any one of the above [1] to

[0012] , wherein the cylindrical lithium secondary battery is a 46110 cell, a 4875 cell, a 48110 cell, a 4880 cell, a 4680 cell, or a 4695 cell.

[0014] A battery pack including a cylindrical lithium secondary battery of any one of the above [1] to

[0013] can be provided. The cylindrical lithium secondary battery of the present invention has an effect in that even if it explodes and generates flames, no holes or tears are generated in the side of the cell, and the flames are guided in the direction of the vent, so that the flames are not directly transmitted to nearby unit cells. For this reason, a battery pack including the cylindrical lithium secondary battery of the present invention as a unit cell has high safety. The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention; therefore, the present invention should not be interpreted as being limited to matters described in such drawings. FIG. 1 is a perspective view of a cylindrical lithium secondary battery according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a cylindrical lithium secondary battery according to one embodiment of the present invention. Figure 3 is an enlarged cross-sectional view of the first collector plate and its surroundings shown in Figure 2. Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following embodiments. In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components in each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification. In addition, terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that an inventor can appropriately define the concept of a term in order to explain his or her own invention in the best way. Hereinafter, the present invention will be described in more detail. A cylindrical lithium secondary battery and / or battery pack according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination between technically possible configurations among the configurations below. FIG. 1 is a perspective view of a cylindrical lithium secondary battery according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of a cylindrical lithium secondary battery according to one embodiment of the present invention. A cylindrical lithium secondary battery (1) (hereinafter, “secondary battery”) according to one embodiment of the present invention may include an electrode assembly (10) and a battery can (20) that accommodates the electrode assembly (10). The electrode assembly (10) may include an anode, a cathode, and a separator interposed between the anode and the cathode. In addition, the electrode assembly (10) may be provided with a first electrode tab (11) connected to one of the anode and the cathode, and a second electrode tab (12) connected to the other of the anode and the cathode. In more detail, the electrode assembly (10) may be of a jelly-roll type. The electrode assembly (10) may be manufactured by winding a laminate in which a positive electrode, a separator, a negative electrode, and a separator are sequentially laminated. A hollow (C) formed long in the height direction may be formed in the center of the electrode assembly (10). In order to insulate the electrode assembly (10) from the inner circumference of the battery can (20), a separator may be positioned at the outermost surface of the electrode assembly (10). The first electrode tab (11) and the second electrode tab (12) may be provided at both ends of the electrode assembly (10) in the height direction. More specifically, the uncoated portion of one of the positive and negative electrodes may be located at one end of the electrode assembly (10) and may function as the first electrode tab (11). The uncoated portion of the other of the positive and negative electrodes may be located at the other end of the electrode assembly (10) and may function as the second electrode tab (12). Each electrode tab (11)(12) can extend along the winding direction of the electrode assembly (10). Alternatively, each electrode tab (11)(12) may include a plurality of foil flags arranged along the winding direction of the electrode assembly (10). A first collector plate (50), which will be described later, can be coupled to the first electrode tab (11), and a second collector plate (60), which will be described later, can be coupled to the second electrode tab (12). The electrode assembly (10) can be accommodated in the battery can (20) with each collector plate (50) (60) coupled to each electrode tab (11) (12). For example, the first electrode tab (11) may be the uncoated portion of the negative electrode, and the second electrode tab (12) may be the uncoated portion of the positive electrode. In this case, the first collector plate (50) may be referred to as the negative collector plate, and the second collector plate (60) may be referred to as the positive collector plate. This is an example of a tab-less structure, which will be described later. The battery can (20) may be approximately cylindrical. One side of the battery can (20) in the height direction may be provided with a surface (20a), and the other side may be provided with an opening. The electrode assembly (10) can be accommodated in the battery can (20) together with the electrolyte through the opening. The battery can (20) may have a conductive material such as metal. The battery can (20) may be electrically connected to the first electrode tab (11) through the first current collector plate (50) described later. The battery can (20) may have the same polarity as the first electrode tab (11). A beading portion (21) and a crimping portion (22) may be formed in the battery can (20). The beading portion (21) and the crimping portion (22) may be formed adjacent to the opening portion of the battery can (20). The beading portion (21) can be formed by pressing the perimeter of the battery can (20) inwardly at a radius. The inner diameter of the beading portion (21) can be smaller than the inner diameter of the battery can (20). The beading portion (21) can be formed in a state where the electrode assembly (10) is accommodated in the battery can (20). The electrode assembly (10) can be restrained between one side (20a) of the battery can (20) and the beading portion (21) with respect to the height direction of the battery can (20). The beading portion (21) can prevent the electrode assembly (10) from being separated from the opening of the battery can (20). In addition, the beading portion (21) can be combined with the first collector plate (50). For example, the first collector plate (50) can be welded to the beading portion (21). As a result, the first collector plate (50) can electrically connect the first electrode tab (11) and the battery can (20). The crimping portion (22) may be formed adjacent to the beading portion (21). The crimping portion (22) may be formed by bending an end of the circumferential surface of the battery can (20) inwardly along a radius. The crimping portion (22) may be formed after the first collector plate (50) is joined to the beading portion (21). The crimping portion (22) may restrain the cap plate (30) described later together with the beading portion (21). The secondary battery (1) may include a cap plate (30) that covers the opening of the battery can (20). The cap plate (30) may have a roughly circular plate shape. The cap plate (30) may form the appearance of the secondary battery (1) together with the battery can (20). The edge of the cap plate (30) may be restrained between the beading portion (21) and the crimping portion (22) of the battery can (20). The cap plate (30) may have a material having high rigidity, such as metal. The cap plate (30) may be insulated from the battery can (20) and may not have polarity. In more detail, a sealing portion (72) of a spacer (70) to be described later may be interposed between the cap plate (30) and the battery can (20). This will be described in detail later. The secondary battery (1) may include a terminal (40) fixed through one side (20a) of the battery can (20). The terminal (40) may penetrate one side (20a) of the battery can (20), more specifically, the center of the side (20a). A part of the terminal (40) may be exposed to the outside of the battery can (20), and another part may be located inside the battery can (20). For example, the terminal (40) may be fixed to the one side (20a) of the battery can (20) by riveting. The terminal (40) may have a conductive material such as metal. The terminal (40) can be combined with a second collector plate (60) to be described later. For example, the second collector plate (60) can be welded to the terminal (40). As a result, the second collector plate (60) can electrically connect the second electrode tab (12) and the terminal (40). The terminal (40) may be insulated from the battery can (20). More specifically, an insulating gasket (G) may be interposed between the terminal (40) and the battery can (20). However, this is not limited thereto, and an insulating coating layer may be formed on a portion of the terminal (40), or a method of structurally fixing the terminal (40) while separating the terminal (40) and the battery can (20) from each other may be applied. The insulating gasket (G) can be deformed during riveting of the terminal (40) and bent toward the inner surface of one side (20a) of the battery can (20). The insulating gasket (G) can seal the gap between the terminal (40) and the battery can (20). By means of the insulating gasket (G), that is, the battery can (20) and the terminal (40) can have opposite polarities. More specifically, the battery can (20) can have the same polarity as the first electrode tab (11), and the terminal (40) can have the same polarity as the second electrode tab (12). Accordingly, one side (2a) of the battery can (20) can function as a first terminal having the first polarity, and the terminal (40) can function as a second terminal having the second polarity. Since one side (2a) of the battery can (20) and the terminal (40) are positioned adjacent to each other, the internal space required for installing the bus bar in a battery module including a plurality of secondary batteries (1) can be reduced, and the energy density of the battery module can be increased. The secondary battery (1) may include a first collector plate (50) that electrically connects a first electrode tab (11) and a battery can (20). For example, the first electrode tab (11) may be connected to a negative electrode of the electrode assembly (10), and the first collector plate (50) may be referred to as a negative electrode collector plate. The secondary battery (1) may include a second collector plate (60) that electrically connects the second electrode tab (11) and the terminal (40). For example, the second electrode tab (12) may be connected to the positive electrode of the electrode assembly (10), and the second collector plate (60) may be referred to as a positive electrode collector plate. The first collector plate (50) and the second collector plate (60) can be positioned within the battery can (20). The first collector plate (50) can be positioned between the electrode assembly (10) and the cap plate (30) with respect to the height direction of the battery can (20). The first collector plate (50) can be coupled to the first electrode tab (11). In more detail, the first collector plate (50) can be welded to the first electrode tab (11). In addition, the first collector plate (50) can be welded to the battery can (20), more specifically, to the beading portion (21). The second collector plate (60) may be positioned between the electrode assembly (10) and one side (20a) of the battery can (20) with respect to the height direction of the battery can (20). The second collector plate (60) may be coupled to the second electrode tab (12). In more detail, the second collector plate (60) may be welded to the second electrode tab (12). In addition, the second collector plate (60) may be welded to the terminal (40). The secondary battery (1) may include a spacer (70) positioned between the cap plate (30) and the electrode assembly (10). More specifically, the spacer (70) may be positioned between the cap plate (30) and the first current collector plate (50). The height of the spacer (70) may correspond to the distance between the cap plate (30) and the electrode assembly (10). The spacer (70) may prevent the electrode assembly (10) from moving or shaking within the battery can (20). The secondary battery (1) may include an insulator (80) positioned between the electrode assembly (10) and the battery can (20). More specifically, the insulator (80) may be positioned between the second collector plate (60) and the battery can (20). The insulator (80) can insulate the second collector plate (60) and the electrode assembly (10) from the battery can (20). The insulator (80) can have a resin material having insulating properties. A hole through which a terminal (40) passes may be formed in the center of the insulator (80). Through the hole, the terminal (40) may be coupled to the second collector plate (60). The insulator (80) may have a roughly cap-shaped shape. In this case, a part of the insulator (80) may be positioned between one side (20a) of the battery can (20) and the second collector plate (60), and another part may be positioned between the outer perimeter of the second collector plate (60) and the inner perimeter of the battery can (20). However, it is not limited thereto, and it is also possible for the insulator (80) to have a plate shape positioned between one side (20a) of the battery can (20) and the second collector plate (60). In this case, an insulating tape separate from the insulator (80) may be interposed between the outer perimeter of the second collector plate (60) and the inner perimeter of the battery can (20). The height of the insulator (80) may correspond to the vertical distance between one side (20a) of the battery can (20) and the electrode assembly (10). The insulator (80) together with the spacer (70) may prevent the electrode assembly (10) from moving or shaking within the battery can (20). Figure 3 is an enlarged cross-sectional view of the first collector plate and its surroundings shown in Figure 2. As described above, the first collector plate (50) can be coupled to the first electrode tab (11). More specifically, at least a portion of the first electrode tab (11) can be bent toward the hollow portion (C) of the electrode assembly (10), and the first collector plate (50) can be coupled to the bent portion of the first electrode tab (11). Although not shown in FIG. 3, the bent portions of a plurality of adjacent first electrode tabs (11) can overlap each other. Accordingly, the height of the first electrode tab (11) is reduced, so that the energy density of the secondary battery (1) can be improved. In addition, since the bonding area between the first electrode tab (11) and the first current collector plate (50) increases, the bonding force between the first electrode tab (11) and the first current collector plate (50) can be improved and the resistance can be reduced. In more detail, the first collector plate (50) may include a center portion (51), a tab coupling portion (52) extending outwardly from the center portion (51) and coupled with the first electrode tab (11), a can coupling portion (53) coupled with the battery can (20) and spaced apart from the tab coupling portion (52), and a bridge (54) connecting the can coupling portion (53) and the center portion (51). The center portion (51) may be located at the center of one side (e.g., the lower side) of the electrode assembly (10). The center portion (51) may have an approximately circular shape. A center hole (51a) may be formed in the center portion (51). The center hole (51a) may face the hollow space (C) of the electrode assembly (10). The center hole (51a), together with the hollow space (C), may function as a passage for insertion of a welding rod for joining the terminal (40) and the second collector plate (60) or for laser irradiation. In addition, the center hole (51a) may function as a passage for allowing smooth electrolyte impregnation into the inside of the electrode assembly (10) when the electrolyte is poured. The tab coupling portion (52) can extend radially outward from the center portion (51). The tab coupling portion (52) can be coupled with the first electrode tab (11). A plurality of tab coupling portions (52) can be provided, and a plurality of tab coupling portions (52) can extend radially from the center portion (51). The width of the tab joint (52) can become wider as it gets farther away from the center portion (51). As a result, the tab joint (52) can widely cover the folded portion of the first electrode tab (11) and prevent the folded portion of the first electrode tab (11) from lifting. The tab joint (52) may be non-overlapping with the beading portion (21) in the height direction of the battery can (20). That is, the tab joint (52) may not be located between the electrode assembly (10) and the beading portion (21). Accordingly, the tab joint (52) may be prevented from being damaged by being caught between the electrode assembly (10) and the beading portion (21) due to the sizing process. Sizing may mean a compression process of reducing the height of the beading portion (21) to reduce the height of the secondary battery (1) after the beading portion (21) and the crimping portion (22) are formed in the battery can (20) containing the electrode assembly (10). The can coupling portion (53) can be coupled to the battery can (20), more specifically, to the beading portion (21). The can coupling portion (53) can be coupled to a surface of the beading portion (21) that is relatively far from the electrode assembly (10). The can coupling portion (53) may have a predetermined height difference with respect to the center portion (51) and the tab coupling portion (52). The height difference may mean a distance between the tab coupling portion (52) and the can coupling portion (53) with respect to the height direction of the battery can (20). The height difference may correspond to the height of the beading portion (21). That is, the distance between the tab coupling portion (52) and the can coupling portion (53) with respect to the height direction of the battery can (20) may be equal to or similar to the height of the beading portion (21). The can joint (53) can be pressed by the sealing portion (72) to be described later. In more detail, the can joint (53) can be interposed and fixed between the sealing portion (72) and the beading portion (21). The can coupling portion (53) may be spaced apart from the tab coupling portion (52). More specifically, the can coupling portion (53) and the tab coupling portion (52) may be connected to the center portion (51), respectively, and the can coupling portion (53) and the tab coupling portion (52) may not be directly connected to each other. Accordingly, when impact or vibration is applied to the secondary battery (1), the stress acting on the coupling portion between the tab coupling portion (52) and the first electrode tab (11) and the coupling portion between the can coupling portion (53) and the battery can (20) is dispersed, thereby minimizing the possibility of damage to the first collector plate (50). A plurality of can coupling parts (53) may be provided. With respect to the circumferential direction of the first collector plate (50), the can coupling parts (53) and the tab coupling parts (52) may be arranged alternately. The can coupling portion (53) can be extended along the inner circumference of the battery can (20). That is, the can coupling portion (53) can be extended in the circumferential direction of the beading portion (21). Accordingly, the contact area between the can coupling portion (53) and the beading portion (21) increases, so that the coupling between the can coupling portion (53) and the beading portion (21) is stably formed, and the resistance between the can coupling portion (53) and the beading portion (21) can be reduced. The edges on both sides of the can joint (53) can be formed along the radial direction of the first collector plate (50). An imaginary line extending along the edges on both sides can pass through the center of the first collector plate (50). The can coupling portion (53) and the tab coupling portion (52) can be non-overlapping with respect to the height direction of the battery can (20). Accordingly, when a plurality of first collector plates (50) are loaded before being coupled to the electrode assembly (10), the can coupling portion (53) of one first collector plate (50) and the tab coupling portion (52) of another first collector plate (50) can be prevented from interfering with each other. The bonding strength between the can joint (53) and the battery can (20), more specifically, the can joint (53) and the beading portion (21), may be greater than the bonding strength between the tab joint (52) and the first electrode tab (11). As a result, the can joint (53) can be stably bonded to the rigid battery can (20). The bridge (54) can connect the can coupling portion (53) and the center portion (51). The bridge (54) can extend radially outward from the center portion (51) and can be spaced apart from the tab coupling portion (52) with respect to the circumferential direction of the first collector plate (50). A plurality of bridges (54) may be provided, similar to the can coupling portion (53), and a plurality of bridges (54) may extend radially from the center portion (51). With respect to the circumferential direction of the first collector plate (50), the bridges (54) and the tab coupling portions (52) may be arranged alternately. Since there is a height difference between the center portion (51) and the can joint portion (53), the bridge (54) can be formed to be inclined. The bridge (54) can be extended to be inclined in a direction away from the electrode assembly (10) as it gets farther away from the center portion (51). The slope of the bridge (54) may become gentler as it gets farther from the center portion (51). More specifically, the bridge (54) may include a first slope portion (54a) extending from the center portion (51) and a second slope portion (54b) extending from the first slope portion (54a) and having a gentler slope than the first slope portion (54a). However, it is not limited to this, and the bridge (54) may be formed to be rounded in a direction that becomes gentler as it gets further away from the center portion (51). In this way, it is possible to prevent the bridge (54) from being excessively deformed due to the sizing process and the center portion (51) and the first electrode tab (11) coupled to the center portion (51) from being lifted. During the sizing process, the beading portion (21) is compressed toward the electrode assembly (10) and its height is reduced, so that the tab coupling portion (53) coupled to the beading portion (21) can also move toward the electrode assembly (10). As a result, a repulsive force in the direction away from the electrode assembly (10) is applied to the center portion (51) connected to the tab coupling portion (53) and the bridge (54). If the inclination of the bridge (54) is constant or becomes steeper as it gets farther from the center portion (51), the repulsive force is greatly applied to the center portion (51), and as a result, there is a concern that the center portion (51) and the first electrode tab (11) coupled thereto may be lifted. On the other hand, the bridge (54) according to the present embodiment can minimize the lifting phenomenon of the center portion (51) and the first electrode tab (11) caused by the sizing process. In addition, the process of pressing the outer circumference of the battery can (20) inwardly to form the beading portion (21) can be performed in a state where the electrode assembly (10) to which the first collector plate (50) is coupled is accommodated in the battery can (20). In this process, since the bridge (54) has a gentle slope as it gets farther from the center portion (51), the beading portion (21) can be easily formed without interference with the bridge (54). Meanwhile, the edge of the cap plate (30) may be positioned between the beading portion (21) and the crimping portion (22) of the battery can (20) and may be fixed by a sealing portion (72) to be described later. The cap plate (30) may not protrude relative to the battery can (20). For example, when the cap plate (30) is positioned at the lower end of the battery can (20), the bottom surface of the plate portion (31) of the cap plate (30) may be positioned on the same surface as the bottom surface of the battery can (20) or higher. Accordingly, the cap plate (30) may not be pressed upward by the bottom surface supporting the battery can (20), and the phenomenon in which the pressure required for the rupture of the venting portion (34) differs from the design value due to the weight of the secondary battery (1) may be prevented. A venting portion (34) may be formed in the cap plate (30). The venting portion (34) may be formed to have a thinner thickness than the surrounding area. Accordingly, the venting portion (34) may be structurally weaker than the surrounding area, and when the internal pressure of the battery can (20) increases beyond a preset value, the venting portion (34) may be preferentially broken. The venting portion (34) may be formed along the circumferential direction of the cap plate (30). For example, the venting portion (34) may form a closed loop shape, such as a ring. Accordingly, when the venting portion (34) is broken, an area of ​​the cap plate (30) located inside the venting portion (34) can be easily separated to form an opening, and gas inside the battery can (20) can be quickly discharged. The venting portion (34) can be formed by notching both sides of the cap plate (30) to a predetermined depth to partially reduce the thickness of the cap plate (30). However, this is not limited to this, and it may also be possible to form the venting portion (34) by notching only one side of the cap plate (30). Meanwhile, the spacer (70) may have an elastic material to effectively absorb shock or vibration applied to the secondary battery (1). The height of the spacer (70) may correspond to the distance between the first collector plate (50) and the cap plate (30). In this case, the main body (71) can effectively prevent the electrode assembly (10) from moving within the battery can (20) due to the clearance formed between the first collector plate (50) and the cap plate (30). Accordingly, the spacer (70) can prevent damage from occurring at the joining portion between the electrode assembly (10) and the first collector plate (50) and / or the joining portion between the first collector plate (50) and the battery can (20). In the spacer (70), an opening may be formed that faces the hollow space (C) of the electrode assembly (10) through the center hole (51a) of the first collector plate (50). The opening, together with the center hole (51a) and the hollow space (C), may function as a passage for inserting a welding rod or a passage for laser irradiation. In addition, the opening may function as a passage for allowing smooth electrolyte impregnation into the inside of the electrode assembly (10). The sealing portion (72) may be formed integrally with the spacer (70), but is not limited thereto. The sealing portion (72) may be a circular ring shape extending along the inner circumference of the battery can (20). The sealing portion (72) may be fixed between the beading portion (21) and the crimping portion (22) of the battery can (20). A part of the sealing portion (72) may be bent together with the crimping portion (22) to wrap around the edge of the cap plate (30). As a result, the sealing portion (72) may firmly seal between the cap plate (30) and the battery can (20). In this way, the sealing portion (72) may function as a gasket for improving the fixing force of the cap plate (30) and the sealing force of the battery can (20). The sealing portion (72) can press the can coupling portion (53) of the first collector plate (50) toward the beading portion (21) to further strengthen the coupling between the can coupling portion (53) and the beading portion (21). In addition, the sealing portion (72) can insulate the can coupling portion (53) and the cap plate (30). The tensile strength of the current collector plate included in the lithium secondary battery of the present invention is 200 N / mm 2 Up to 370 N / mm 2 , preferably 230 N / mm 2 Up to 350 N / mm 2 , most preferably 250 N / mm 2 Up to 330 N / mm 2 It can be. If the current collector plate included in the lithium secondary battery of the present invention has a tensile strength in this range, when a flame occurs in the lithium secondary battery, the flame will not be directed to the side but will be directed upwards of the battery, thereby preventing the flame from spreading to surrounding lithium secondary batteries. In addition, if the current collector plate included in the lithium secondary battery of the present invention has a tensile strength in this range, the current collector plate can be prevented from being excessively stretched or broken when the lithium secondary battery is actually operated. The above tensile strength was measured using an extensometer (Manufacturer: Nanotech, Product name: Universal Testing Machine UTM). The tensile strength of the above collector plate can be affected by various factors, such as the collector plate heat treatment method, processing method such as the rolling method, and whether or not it is plated. The above current collector plate may have a thickness of 50 ㎛ to 500 ㎛, preferably 100 ㎛ to 400 ㎛, and more preferably 150 ㎛ to 350 ㎛. When the thickness of the current collector plate satisfies the above range, when a flame occurs in the lithium secondary battery, the flame does not direct to the side but directs upwards of the battery, thereby preventing the flame from spreading to surrounding lithium secondary batteries. In addition, when the current collector plate included in the lithium secondary battery of the present invention has a thickness within the above range, it may have a level of resistance capable of providing appropriate cell performance and may have less physical deformation when the cell is operated. The above beading portion may have a thickness of 0.4 mm to 0.6 mm, preferably 0.4 mm to 0.5 mm. When the thickness of the above beading portion satisfies the above range, when a flame occurs in the lithium secondary battery, the flame does not go to the side but rather goes upwards of the battery, thereby preventing the flame from spreading to surrounding lithium secondary batteries. The above-mentioned current collector plate may be a copper film, a nickel-plated copper film, or the like, and may have an elongation at 25°C of 2% to 50%, preferably 5% to 30%, and more preferably 5% to 20%. The elongation can be measured using an extensometer (manufacturer: Nanotech, product name: universal material testing machine UTM). Specifically, the electrode assembly of the present invention has a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound in one direction, and may be, for example, a jelly-roll type electrode assembly. The electrode assembly of the present invention can be manufactured by winding in one direction a laminate formed by sequentially stacking a separator, a positive electrode, a separator, and a negative electrode at least once. At this time, the positive and negative electrodes have a structure in which an active material layer is formed on a sheet-shaped current collector, and may include a non-conductive portion in which an active material layer is not formed in some area of ​​the current collector. By using the positive and negative electrodes including the non-conductive portions as described above, it is possible to implement a battery having a tab-less structure in which at least a portion of the non-conductive portions of the positive and negative electrodes define electrode tabs without providing separate electrode tabs. Specifically, the non-coated portion can be formed long along the winding direction at one end of the current collector, and a collector plate is bonded to each of the positive non-coated portion and the negative non-coated portion, and the collector plate is connected to the electrode terminal, thereby implementing a battery with a tab-less structure. For example, a battery having a tab-less structure can be manufactured by the following method. First, a separator, a cathode, a separator, and an anode are sequentially laminated so that the non-coated parts of the cathode and the anode are positioned in opposite directions, and then wound in one direction to manufacture an electrode assembly. Then, the non-coated parts of the cathode and the anode are folded in the direction of the hollow (C) which is the center of the winding, and then a current collector is welded to the non-coated part of the cathode and the non-coated part of the anode to join them, and the current collector is connected to the electrode terminal, thereby manufacturing a battery having a tab-less structure. Meanwhile, the current collector has a larger cross-sectional area than the strip-type electrode tab, and since the resistance is inversely proportional to the cross-sectional area of ​​the path through which the current flows, if a secondary battery is formed with the above structure, the cell resistance can be significantly reduced. Meanwhile, the positive and negative electrode portions may be processed into a plurality of independently foldable segments, and at least some of the plurality of segments may be folded toward the hollow portion (C), which is the winding center of the electrode assembly. The above segments can be formed by processing the positive and negative current collectors through a metal foil cutting process such as laser notching, ultrasonic cutting, or punching. When the non-conductive portions of the positive and negative electrodes are processed in the form of multiple segments, the stress applied to the non-conductive portion during bending can be reduced, thereby preventing deformation or damage to the non-conductive portion, and improving the welding characteristics with the current collector plate. The collector plate and the plain portion are generally joined by welding. In order to improve the welding characteristics, strong pressure should be applied to the welding area of ​​the plain portion to fold the plain portion as flat as possible. However, during this bending process, the shape of the plain portion may be distorted and deformed irregularly, and the deformed portion may come into contact with an electrode of the opposite polarity, causing an internal short circuit or causing micro-cracks in the plain portion. However, if the plain portions of the positive and negative electrodes are processed into a plurality of independently bendable segments, the stress applied to the plain portion during bending can be relieved, thereby minimizing deformation and damage to the plain portion. In addition, when the non-conductive portion is processed in the form of segments as described above, overlap occurs between the plurality of segments during folding, which increases the welding strength with the current collector plate, and when using the latest technology such as laser welding, it is possible to prevent the problem of the laser penetrating into the electrode assembly and melting away the separator or active material. Preferably, at least some of the plurality of folded segments may overlap on the upper and lower sides of the electrode assembly, and the current collector plate may be bonded on the plurality of overlapped segments. Cylindrical lithium secondary battery Next, a cylindrical lithium secondary battery according to the present invention will be described. The cylindrical lithium secondary battery according to the present invention may be a large-capacity cylindrical secondary battery having a rated capacity of 25 Ah or more. The cylindrical lithium secondary battery according to the present invention may be a large cylindrical battery having a form factor ratio (defined as the ratio of the diameter (Ф) to the height (H) of the cylindrical battery, i.e., the value obtained by dividing the diameter by the height) of 0.4 or more. Here, the form factor means a value representing the diameter and height of the cylindrical battery. The cylindrical battery according to the present invention may be, for example, a 46110 cell (diameter 46 mm, height 110 mm, form factor ratio 0.418), a 4875 cell (diameter 48 mm, height 75 mm, form factor ratio 0.640), a 48110 cell (diameter 48 mm, height 110 mm, form factor ratio 0.436), a 4880 cell (diameter 48 mm, height 80 mm, form factor ratio 0.600), a 4680 cell (diameter 46 mm, height 80 mm, form factor ratio 0.575), a 4695 cell (diameter 46 mm, height 95 mm, form factor ratio 0.484). In the numerical value indicating the form factor, the first two numbers indicate the diameter of the cell, and the next two or three numbers indicate the height of the cell. The cylindrical lithium secondary battery according to the present invention significantly reduces the amount of gas generated compared to conventional batteries, and thus can realize excellent safety even in large cylindrical batteries having a form factor ratio of 0.4 or more. Meanwhile, the cylindrical battery according to the present invention is a battery with a tab-less structure that does not include electrode tabs. The battery of the above tab-less structure may have, for example, a structure in which the positive and negative electrodes each include a non-conductive portion on which an active material layer is not formed, the positive electrode non-conductive portion and the negative electrode non-conductive portion are respectively positioned at the top and bottom of the electrode assembly, a current collector plate is bonded to the positive electrode non-conductive portion and the negative electrode non-conductive portion, and the current collector plate is connected to the electrode terminal. The above cylindrical lithium secondary battery can be applied to various devices. For example, it can be applied to electric vehicles such as electric bicycles, electric cars, and hybrid electric vehicles (HEVs). Accordingly, according to another embodiment of the present invention, a battery module including the cylindrical lithium secondary battery as a unit cell and a battery pack including the same are provided. The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, including power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems. Hereinafter, the present invention will be described in more detail through specific examples. Example Example 1 A jelly-roll type electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, stacking them in the order of separator / positive electrode / separator / negative electrode, and then winding them. After inserting the electrode assembly into a cylindrical battery can, an electrolyte was injected, and the opening of the battery can was sealed with a cap plate. A 200 ㎛ thick copper plate was used as a cathode plate, and the cap plate and electrode assembly were electrically connected by welding the cap plate and the electrode assembly. The tensile strength of the cathode plate was 275 N / mm. 2 , and the elongation at 25℃ was 20.0%. Example 2 A jelly-roll type electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, stacking them in the order of separator / positive electrode / separator / negative electrode, and then winding them. After inserting the electrode assembly into a cylindrical battery can, an electrolyte was injected, and the opening of the battery can was sealed with a cap plate. A 200 ㎛ thick copper plate was used as a cathode plate, and the cap plate and electrode assembly were electrically connected by welding the cap plate and the electrode assembly. The tensile strength of the cathode plate was 325 N / mm. 2 , and the elongation at 25℃ was 6.5%. Example 3 A jelly-roll type electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, stacking them in the order of separator / positive electrode / separator / negative electrode, and then winding them. After inserting the electrode assembly into a cylindrical battery can, an electrolyte was injected, and the opening of the battery can was sealed with a cap plate. A 300 ㎛ thick copper plate was used as a cathode plate, and the cap plate and electrode assembly were electrically connected by welding the cap plate and the electrode assembly. The tensile strength of the cathode plate was 238 N / mm. 2 , and the elongation at 25℃ was 46.0%. Comparative Example 1 A jelly-roll type electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, stacking them in the order of separator / positive electrode / separator / negative electrode, and then winding them. After inserting the electrode assembly into a cylindrical battery can, an electrolyte was injected, and the opening of the battery can was sealed with a cap plate. A 200 ㎛ thick copper plate was used as a cathode plate, and the cap plate and electrode assembly were electrically connected by welding the cap plate and the electrode assembly. The tensile strength of the cathode plate was 175 N / mm. 2 , and the elongation at 25℃ was 42.5%. Comparative Example 2 A jelly-roll type electrode assembly was manufactured by interposing a separator between the positive and negative electrodes, stacking them in the order of separator / positive electrode / separator / negative electrode, and then winding them. After inserting the electrode assembly into a cylindrical battery can, an electrolyte was injected, and the opening of the battery can was sealed with a cap plate. A 300 ㎛ thick copper plate was used as a cathode plate, and the cap plate and electrode assembly were electrically connected by welding the cap plate and the electrode assembly. The tensile strength of the cathode plate was 380 N / mm. 2 , and the elongation at 25℃ was 3.5%. Experimental example An overcharge experiment was performed using the lithium secondary batteries of Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, the lithium secondary batteries were charged at 1 / 3C to a full charge voltage (4.2 V) with a 1 / 50 C cut off, and then rested for 2 hours to stabilize the voltage. Overcharge was performed on five identically manufactured lithium secondary batteries each with a current of 40 A, and the number of lithium secondary batteries in which the negative current collector plate was lost was counted, and the results are shown in Table 1 below. Number of lithium secondary batteries with a negative electrode collector lost Example 15 / 5ea Example 25 / 5ea Example 35 / 5ea Comparative Example 12 / 5ea Comparative Example 24 / 5ea [Explanation of symbols] 1: Cylindrical lithium secondary battery 10: Electrode assembly 11: 1st electrode tab 12: Second electrode tab 20: Battery can 21: Bidding Department 22: Crimping section 30: Cap plate 34: Benting Department 40: Terminal 50: First Edition 51: Center section 51a: Center Hall 52: Tab joint 53: Can joint 54: Bridge 60: Second Collection Edition 70: Spacer 72: Sealing part

Claims

1. An electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, each of which is wound in one direction; A battery can accommodating the electrode assembly through an opening formed on one side; a cap plate covering the above opening; and A current collector plate is disposed between the electrode assembly and the cap plate and electrically connects the electrode assembly and the battery can. The tensile strength of the above collector plate is 200 N / mm 2 Up to 370 N / mm 2 Cylindrical lithium secondary battery.

2. In claim 1, The above battery can includes a beading portion which is a support portion on which the cap plate is fixed, A cylindrical lithium secondary battery in which the collector plate is connected to the beading portion.

3. In claim 1, The tensile strength of the above collector plate is 230 N / mm 2 Up to 350 N / mm 2 Cylindrical lithium secondary battery.

4. In claim 1, The above current collector plate is a cylindrical lithium secondary battery having a thickness of 50 μm to 500 μm.

5. In claim 2, A cylindrical lithium secondary battery having a thickness of the beading portion of 0.4 mm to 0.6 mm.

6. In claim 1, A cylindrical lithium secondary battery wherein the above current collector plate is a negative current collector plate.

7. In claim 6, The above current collector plate is a cylindrical lithium secondary battery made of a copper film.

8. In claim 1, The above positive and negative electrodes each include a non-conductive portion on which an active material layer is not formed, A cylindrical lithium secondary battery having a tab-less structure in which at least a portion of the positive electrode non-conductive portion or the negative electrode non-conductive portion defines an electrode tab.

9. In claim 8, The positive electrode uncoated portion and the negative electrode uncoated portion are formed along the direction in which the electrode assembly is wound on one end of the positive and negative electrodes, respectively. A current collector is connected to each of the positive electrode uncharged portion and the negative electrode uncharged portion, A cylindrical lithium secondary battery in which the above current collector plate is connected to an electrode terminal.

10. In claim 8, The above positive and negative electrode parts are processed into a plurality of independently foldable segments, A cylindrical lithium secondary battery, wherein at least some of the plurality of segments are bent toward the winding center of the electrode assembly.

11. In claim 10, At least some of the above folded plurality of segments overlap on the upper and lower portions of the electrode assembly, A cylindrical lithium secondary battery in which the current collector plate is bonded to the plurality of overlapping segments.

12. In claim 1, The above cylindrical lithium secondary battery is a cylindrical lithium secondary battery having a form factor ratio of 0.4 or more.

13. In claim 1, The above cylindrical lithium secondary battery is a cylindrical lithium secondary battery having 46110 cells, 4875 cells, 48110 cells, 4880 cells, 4680 cells, or 4695 cells.

14. A battery pack comprising a cylindrical lithium secondary battery according to any one of claims 1 to 13.

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