Secondary battery

Abstract

A secondary battery includes: a case; an electrode assembly accommodated in the case; a first current collector plate and a second current collector plate electrically connected to the electrode assembly and accommodated in the case; a cap assembly coupled to one side of the case and having first and second terminal portions electrically connected to the first and second current collector plates, respectively; and first and second side retainers coupled to the first and second current collector plates, respectively, and having a protrusion facing an end portion of an inner wall of the case. The side holder is configured to eliminate a gap between the current collector plate and the case so that the electrode assembly can be stably supported. Accordingly, it is possible to prevent the electrode assembly from moving and effectively protect the electrode assembly from external impact or vibration.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0126147 filed in the Korean Intellectual Property Office on September 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure relate to a secondary battery capable of protecting an electrode assembly from external impact. Background Art

[0004] The secondary battery includes: an electrode assembly, which is stacked or wound with a separator between the positive electrode plate and the negative electrode plate; a case, which contains the electrode assembly and the electrolyte; and a cap assembly that seals the case. The electrode assembly has a substrate tab that protrudes laterally or upward, and the substrate tab is gathered to one side and welded to the collector plate. The collector plate is electrically connected to a terminal provided in the cap assembly.

[0005] The electrode assembly is configured to be connected to the current collector plate through the substrate tab, but it is not separately fixed inside the case. Therefore, since there is no part for fixing the electrode assembly except for the part connected to the current collector plate, there is a problem that the electrode assembly and the current collector plate may move inside the case and be damaged due to external impact or vibration.

[0006] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0007] Embodiments of the present disclosure provide a secondary battery capable of protecting an electrode assembly from damage due to an external impact.

[0008] A secondary battery according to aspects of the present disclosure may include: a shell; an electrode assembly accommodated in the shell; a first collector plate and a second collector plate electrically connected to the electrode assembly and accommodated in the shell; a cap assembly coupled to one side of the shell and having a first terminal portion and a second terminal portion electrically connected to the first collector plate and the second collector plate, respectively; and a first side retainer and a second side retainer respectively coupled to the first collector plate and the second collector plate and having protrusions of ends facing the inner wall of the shell.

[0009] The electrode assembly may include a long side portion and a short side portion, and the current collector plate and the first and second side retainers may be on the short side portion of the electrode assembly.

[0010] The first and second side retainers may have sizes substantially equal to sizes of the first and second current collector plates.

[0011] In a front view of the first side retainer and the second side retainer, the protrusion may be dot-shaped.

[0012] The protrusion may have a cylindrical shape, a bent cylindrical shape, a conical shape, or a bent conical shape.

[0013] When the protrusion is in a curved shape, an end portion of the protrusion may face the cap assembly.

[0014] The protrusions may be arranged in multiple rows and columns.

[0015] The protrusions in each of the rows and columns may be spaced substantially equidistant from one another.

[0016] The number of protrusions in each of the rows or columns may be equal.

[0017] The number of protrusions in each of the rows or columns may be different.

[0018] In a front view of the first side retainer and the second side retainer, the protrusion may be linear.

[0019] The protrusion may have a shape expanding left and right such as a cylindrical shape, a bent cylindrical shape, a conical shape, and a bent conical shape.

[0020] When the protrusion is in a curved shape, an end portion of the protrusion may face the cap assembly.

[0021] The protrusions may be arranged in a plurality of rows and in at least one column.

[0022] The protrusions in each of the rows or at least one column may be substantially equidistantly spaced from each other.

[0023] The protrusions may be arranged in a plurality of columns, and the number of protrusions in each column may be equal.

[0024] The protrusions in one column may be symmetrical to the protrusions in an adjacent column.

[0025] The first side retainer and the second side retainer may be bonded to the current collector plate using an adhesive.

[0026] The first side retainer and the second side retainer may be coupled to the current collector plate by an interference fit method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a perspective view of a secondary battery according to an embodiment of the present disclosure.

[0028] Figure 2 is based on Figure 1 A partially exploded perspective view of a secondary battery.

[0029] Figure 3 is exemplified in accordance with Figure 2 A schematic diagram of the configuration before inserting the electrode assembly during the manufacturing process of a secondary battery.

[0030] Figure 4 is exemplified in accordance with Figure 2 Schematic diagram of a configuration of inserting an electrode assembly during a manufacturing process of a secondary battery.

[0031] Figure 5 It is an example based on Figure 3 and Figure 4 Schematic diagram of the combined structure of the electrode assembly and the side retainer.

[0032] Figure 6 2 is a diagram illustrating a protrusion of a side retainer according to an embodiment of the present disclosure.

[0033] Figure 7 It is an example based on Figure 6 FIG. 4 is a diagram of the arrangement of the protrusions of the side retainer of the embodiment illustrated in FIG.

[0034] Figure 8 is a diagram illustrating a protrusion of a side retainer according to another embodiment of the present disclosure.

[0035] Fig. 9 It is an example based on Figure 8 FIG. 4 is a diagram of the arrangement of the protrusions of the side retainer of the embodiment illustrated in FIG. DETAILED DESCRIPTION

[0036] The embodiments of the present disclosure are provided to more fully describe the present disclosure to those skilled in the art, and the following embodiments may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that the present disclosure will be thorough and complete, and will convey aspects and features of the present disclosure to those skilled in the art.

[0037] In addition, in the accompanying drawings, for simplicity and clarity, the size or thickness of various parts is magnified. The same number refers to the same element throughout the text. As used herein, the term "and / or" includes any and all combinations of one or more associated enumerated items. In addition, it will be understood that when element A is referred to as being "connected to" element B, element A can be directly connected to element B or there can be an intervening element C between element A and element B so that element A and element B are indirectly connected to each other.

[0038] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise / include" and / or "comprising / including", when used in this specification, indicate the presence of the described features, quantities, steps, operations, elements, parts and / or groups thereof, but do not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, parts and / or groups thereof.

[0039] It will be understood that although the terms "first", "second", etc. may be used herein to describe various components, elements, regions, layers and / or sections, these components, elements, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one component, element, region, layer and / or section from another. Thus, for example, the first component, first element, first region, first layer and / or first section discussed below may be referred to as a second component, second element, second region, second layer and / or second section without departing from the teachings of the present invention.

[0040] For ease of description, spatially relative terms, such as "below," "below," "below," "above," and "on," etc., may be used herein to describe the relationship of one element or feature, as illustrated in the figure, to other elements or features. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if an element or feature in a figure is flipped, an element described as "below" or "beneath" another element or feature may be oriented "above" or "above" the other element or feature. Thus, the exemplary term "below" may encompass both above and below orientations.

[0041] Hereinafter, a secondary battery according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0042] Figure 1 is a perspective view of a secondary battery according to an embodiment of the present disclosure. Figure 2 is based on Figure 1 A partially exploded perspective view of a secondary battery. Figure 3 is exemplified in accordance with Figure 2 A schematic diagram of a configuration before an electrode assembly is inserted into a case during a manufacturing process of a secondary battery. Figure 4 is exemplified in accordance with Figure 2 Schematic diagram of a configuration of inserting an electrode assembly into a case during a manufacturing process of a secondary battery. Figure 5 It is an example based on Figure 3 and Figure 4Schematic diagram of the combined structure of the electrode assembly and the side retainer.

[0043] See also Figure 1 and Figure 2 , a secondary battery 10 according to an embodiment of the present disclosure may include an electrode assembly 100, a shell 200 for accommodating the electrode assembly 100, and a cap assembly 300 coupled to the shell 200 (e.g., one side thereof). In addition, the secondary battery 10 may include a first collector plate 330 and a second collector plate 340 electrically connected to the electrode assembly 100 and accommodated in the shell 200. In addition, the secondary battery 10 may further include a pair of side retainers 400 respectively disposed between the first collector plate 330 and the second collector plate 340 and the shell 200. In one embodiment, the secondary battery 10 may be a prismatic battery in which the shell 200 has a rectangular parallelepiped shape. However, this is only one embodiment, and the present disclosure may be applied to various types of secondary batteries having different shapes.

[0044] See also Figure 2 , the electrode assembly 100 can be provided by winding a unit stack including a first electrode plate, a second electrode plate, and a separator between the first electrode plate and the second electrode plate, or stacking a plurality of unit stacks. When the electrode assembly 100 is formed by winding, the winding axis may be arranged in a horizontal direction substantially parallel to the longitudinal direction of the cap assembly 300 or in a vertical direction substantially perpendicular to the longitudinal direction of the cap assembly 300. When the electrode assembly 100 is formed by stacking, the long side surfaces of the plurality of unit stacks may be arranged adjacent to each other. The sheet 140 made of an insulating material may be attached to the outside of the electrode assembly 100 by using an insulating tape 150 to insulate the electrode assembly 100 from the housing 200. In one embodiment, the first electrode plate may be a negative electrode plate, and the second electrode plate may be a positive electrode plate. In one or more embodiments, the first electrode plate may be a positive electrode plate, and the second electrode plate may be a negative electrode plate.

[0045] When the first electrode plate is a negative electrode plate, the first electrode plate may be formed by applying a first electrode active material (such as graphite or carbon) to a first electrode current collector provided with a metal foil (such as copper, copper alloy, nickel or nickel alloy). A first uncoated area, which is an area to which the first electrode active material is not applied, may be formed on the first electrode plate. The first uncoated area may be stamped into a certain shape to form a first substrate tab 110. A plurality of first substrate tabs 110 may be bent to one side and welded to the first current collector plate 330. The first current collector plate 330 may be electrically connected to the cap assembly 300.

[0046] When the second electrode plate is a positive electrode plate, the second electrode plate may be formed by applying a second electrode active material (such as a transition metal oxide) to a second electrode current collector provided with a metal foil (such as aluminum or an aluminum alloy). A second uncoated area (not shown) as an area to which the second electrode active material is not applied may be formed on the second electrode plate. The second uncoated area may be stamped into a certain shape to form a second substrate tab, for example, in one or more embodiments, the second substrate tab may have the same shape as the first substrate tab. A plurality of second substrate tabs may be bent to one side and welded to the second current collector plate 340. The second current collector plate 340 may be electrically connected to the cap assembly 300.

[0047] The separator is disposed between the first electrode plate and the second electrode plate to prevent a short circuit and enable lithium ions to move therebetween. In one embodiment, the separator may include polyethylene, polypropylene, or a composite film of polyethylene and polypropylene, but the present disclosure is not limited thereto.

[0048] The electrode assembly 100 having the above configuration may be housed in the housing 200 together with the electrolyte. In some embodiments, the electrolyte may contain a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). In addition, the electrolyte may be a liquid phase or a gel phase. In some embodiments, when an inorganic solid electrolyte is used, the electrolyte may be omitted.

[0049] The electrode assembly 100 is electrically connected to the terminal portions 350, 360 of the cap assembly 300 through the first collector plate 330 and the second collector plate 340, respectively. In one or more embodiments, the electrode assembly 100 may include a long side portion and a short side portion, and the first collector plate 330 and the second collector plate 340 and a pair of side retainers 400 may be on the short side portion of the electrode assembly 100.

[0050] See also Figure 2 , the first collector plate 330 may have a substantially rectangular plate shape (e.g., a substantially planar rectangular shape). The first collector plate 330 may be electrically connected to the first substrate tab 110 by welding. In one or more embodiments, the first collector plate 330 may be made of the same material as the first electrode plate. The first electrode plate as a negative electrode plate and the first terminal portion 350 to be described later are electrically connected through the first collector plate 330. The first collector plate 330 is welded to the first substrate tab 110, and the first collector plate 330 and the first substrate tab 110 face the short side portion 230 of the housing 200.

[0051] See also Figure 2In the embodiment shown in , the second collector plate 340 has the same shape (or substantially the same shape) as the first collector plate 330. Further, the second collector plate 340 is symmetrical with the first collector plate 330. The second collector plate 340 may be welded and electrically connected to the second substrate tab (not shown). In one or more embodiments, the second collector plate 340 may be made of the same material as the second substrate tab of the second electrode plate. The second collector plate 340 is electrically connected to the second electrode plate as a positive electrode plate and the second terminal portion 360 to be described later. The second collector plate 340 is welded to the second substrate tab, and the second collector plate 340 and the second substrate tab face the short side portion 230 of the housing 200.

[0052] In a state in which the first and second collector plates 330 and 340 are connected to the electrode assembly 100 , a side retainer 400 to be described later is inserted into and engaged with the case 200 .

[0053] See again Figure 1 , the housing 200 may be in the form of a generally rectangular box with an open longitudinal top portion, and a receiving space is formed to accommodate the electrode assembly 100. Through the open top portion, the electrode assembly 100 and the electrolyte may be received inside the housing 200. Some components of the cap assembly 300 may be exposed to the outside of the housing 200, and some components may be received inside the housing 200. The housing 200 may include a rectangular bottom portion 210 and four side portions connected to the bottom portion 210. Among the side portions, a side portion having a relatively large area is defined as a long side portion 220, and a side portion having a relatively small area is defined as a short side portion 230. In one embodiment, the electrode assembly 100 may have a flat surface facing the long side portion 220. In a configuration in which the electrode assembly 100 is received in the housing 200, the cap assembly 300 is coupled to the housing 200 and is electrically connected to the electrode assembly 100.

[0054] See also Figure 1 and Figure 2 , the cap assembly 300 may include a cap plate 310 coupled to the case 200, a plurality of insulating members, a first terminal portion 350, and a second terminal portion 360. Only features associated with a welding structure according to one embodiment of the present disclosure will be described below.

[0055] In one or more embodiments, the cover plate 310 is in the form of a substantially rectangular plate, which may be made of the same material as the housing 200. Terminal holes for accommodating the first terminal portion 350 and the second terminal portion 360, respectively, a liquid injection hole 314, an exhaust hole for engaging with the exhaust member 316, etc. may be formed in the cover plate 310. A plurality of insulating members, such as an insulating plate 320 (see Figure 2), may be provided to insulate the cap plate 310 and the electrode assembly 100 from each other.

[0056] The first terminal portion 350 may include a first terminal column 352 and a first terminal plate 354. The first terminal plate 354 may be insulated from the cap plate 310 by an insulating member 328 below the first terminal plate 354. The first terminal column 352 is electrically connected to the first electrode plate by being electrically connected to the first collector plate 330.

[0057] The second terminal portion 360 may include a second terminal column 362, a second terminal plate 364, and a conductive plate 366 below the second terminal plate 364. In one or more embodiments, the second terminal portion 360 is symmetrical to the first terminal portion 350. The conductive plate 366 electrically connects the cap plate 310 to the second terminal plate 364, which is electrically connected to the first terminal column 362. Therefore, the cap plate 310 is connected to the second current collector plate 340 through the second terminal portion 360, and thus can be electrically connected to the second electrode plate. Therefore, the cap plate 310 has the same positive polarity as the second current collector plate 340, and the housing 200 welded to the cap plate 310 also has a positive polarity.

[0058] In the following, we will refer to Figure 2 to Figure 5 The above-mentioned side retainer is described in detail.

[0059] The side retainers 400 are provided in pairs. Each of the side retainers 400 is disposed between the first collector plate 330 and the housing 200, or between the second collector plate 340 and the housing 200. A pair of side retainers 400 have the same shape and are symmetrical with respect to each other. Each of the side retainers 400 may have a plurality of protrusions 410 integrally formed on a rectangular plate, and the plurality of protrusions 410 have ends facing the inner wall of the housing 200. The side retainer 400 may have a length and width corresponding to (e.g., equal to) the length and width of the first collector plate 330 and the second collector plate 340. The protrusion 410 extends outward in a direction facing the inner wall surface (e.g., the short side portion 230) of the housing 200. In one or more embodiments, the side retainer 400 may be made of an insulating material that is elastically deformable and does not react with the electrolyte in the housing 200.

[0060] In order to insert the first collector plate 330 and the second collector plate 340 into the housing 200 in a configuration in which the first collector plate 330 and the second collector plate 340 are coupled to the electrode assembly 100, there is an assembly tolerance between the housing 200 and each of the collector plates 330, 340. The assembly tolerance is a gap for inserting the electrode assembly 100 into the housing 200. However, when an external force is applied to the secondary battery 10 (for example, during handling or use), the electrode assembly 100 may collide with the housing 200 due to the assembly tolerance. Strong external shock or vibration may cause damage to the electrode assembly 100. The protrusion 410 formed on the plate-shaped side retainer 400 is configured to prevent the electrode assembly 100 from colliding with the housing 200. The external shock is absorbed by the protrusion 410 while eliminating the gap through which the electrode assembly 100 can move. In this way, the side retainer 400 is configured to prevent damage to the electrode assembly 100 and the collector plate.

[0061] In addition, the side retainer 400 may be coupled to the first collector plate 330 and the second collector plate 340 using an adhesive. In one or more embodiments, an adhesive layer 420 is provided on the outside of the first collector plate 330 and the second collector plate 340, an insulating film 430 is attached to the adhesive layer 420, and then another adhesive layer 420 is provided on the insulating film 430, so that the side retainer 400 may be attached. The adhesive layer 420 may be formed by applying an adhesive, or may be formed using an adhesive film or a double-sided tape. The adhesive layer 420 and the insulating film 430 may be provided and attached separately. The insulating film 430 is used for insulation between the first collector plate 330 and the housing 200 or between the second collector plate 340 and the housing 200, and an insulating film 430 provided with an adhesive layer 420 on both sides of the insulating film 430 may be used. Through the insulating film 430, the side retainer 400 may be coupled to the first collector plate 330 and the second collector plate 340, respectively. In one or more embodiments, a protrusion or a groove is formed on the outside of the first collector plate 330 and the second collector plate 340, and a groove or a protrusion corresponding thereto is formed on the side retainer 400 to be coupled to each other. In one or more embodiments, a hook may be provided on one of the first collector plate 330, the second collector plate 340, and the side retainer 400, and a hook groove may be provided on the other, so that the side retainer 400 can be coupled to the first collector plate 330 and the second collector plate 340. The mechanical method for coupling the groove and the protrusion or the hook and the hook groove, etc., may be referred to as an interference fit method. The coupling of the side retainer 400 and the collector plates 330, 340 is not limited to the above-described embodiments.

[0062] Hereinafter, various types of the side retainers 400 will be described.

[0063] Figure 62 is a diagram illustrating a protrusion of a side retainer according to an embodiment of the present disclosure. Figure 7 It is an example based on Figure 6 FIG. 4 is a diagram of the arrangement of the protrusions of the side retainer of the embodiment illustrated in FIG. Figure 8 is a diagram illustrating a protrusion of a side retainer according to another embodiment of the present disclosure. Fig. 9 It is an example based on Figure 8 FIG. 4 is a diagram of the arrangement of the protrusions of the side retainer of the embodiment illustrated in FIG.

[0064] See also Figure 6 , the side retainer 400 may have various types of protrusions 410. The protrusion 410 may be various shapes, such as a cylindrical shape as in Example 1, a curved cylindrical shape as in Example 2, a conical shape as in Example 3, or a curved conical shape as in Example 4. When the protrusion 410 is a curved shape, the end of the protrusion 410 may be disposed toward the cover plate 310, that is, the end of the protrusion 410 may face the cover assembly 300. In addition, when the protrusion 410 is a curved shape, the protrusion 410 may be oriented obliquely when the side retainer 400 is viewed from the side. The protrusion 410 may be located on one side of the side retainer 400. Figure 7 As shown in , when the side retainer 400 is observed from the front, the protrusion 410 can appear to be a single point. For convenience, these shapes of protrusions are referred to as linear protrusions. The protrusions 410 can be arranged in multiple rows and columns and spaced equidistantly (or substantially equidistantly) from each other. The number of protrusions 410 in each row or column can be equal. In one or more embodiments, the protrusions 410 can be spaced equidistantly (or substantially equidistantly) from each other, but different numbers of protrusions 410 can be arranged in two rows or two columns or more rows or more columns (e.g., in each row or column).

[0065] See also Figure 8 , the side retainer 400 may have a protrusion 410, wherein Figure 6 The protrusions in the matrix expand in a certain direction. Figure 8 The embodiment shown in FIG. Figure 6 The protrusions shown in the figure are protrusions 410 extending or expanding left and right. For convenience, these protrusions are referred to as planar protrusions. When the protrusions 410 are in a curved form, the ends of the protrusions 410 may be positioned toward the cover plate 310, that is, the ends of the protrusions 410 may face the cover assembly 300. When the side retainer 400 is viewed from the front, as shown in FIG. Fig. 9 As shown in FIG. 4 , the protrusions 410 may appear to be a line. In one or more embodiments, the protrusions 410 may be spaced equidistant (or substantially equidistant) from each other. Fig. 9In the front example 1 in FIG. 1 , an embodiment in which the protrusions 410 are arranged in a straight line and have equal spacing (or substantially equal spacing) with each other is shown. In one or more embodiments, the protrusions 410 may be arranged in multiple columns and the protrusions 410 in each column may be arranged to be symmetrical (or substantially symmetrical) with each other, and the number of protrusions 410 in each column may be equal. Fig. 9 In the front example 2 in FIG. 1 , a plurality of protrusions 410 are arranged diagonally in two columns and the protrusions 410 in the first column and the second column are symmetrical (or substantially symmetrical) to each other. However, the shape and arrangement of the protrusions are not limited to the above-described embodiment.

[0066] As described above, according to an embodiment of the present disclosure, by including the side retainer 400, the gap between the current collector plate and the case 200 can be eliminated, and the electrode assembly 100 can be stably supported. Therefore, the electrode assembly can be prevented from moving and the electrode assembly 100 can be effectively protected from external shock or vibration.

[0067] Although the above-mentioned embodiments have been described to practice the present disclosure, it should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation, and that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the claims.

Claims

1. A secondary battery comprising: case; an electrode assembly housed in the housing; a first current collector plate and a second current collector plate electrically connected to the electrode assembly and housed in the case; a cap assembly coupled to one side of the case and including a first terminal portion electrically connected to the first current collector plate and a second terminal portion electrically connected to the second current collector plate; as well as A first side retainer coupled to the first current collector plate and a second side retainer coupled to the second current collector plate, wherein each of the first side retainer and the second side retainer includes a plurality of protrusions having ends facing an inner wall of the case.

2. The secondary battery according to claim 1, wherein the electrode assembly includes a long side portion and a short side portion, and wherein the first and second current collector plates and the first and second side retainers are on the short side portions of the electrode assembly. 3 . The secondary battery according to claim 1 , wherein the first and second side retainers have sizes equal to sizes of the first and second current collector plates. 4 . The secondary battery according to claim 1 , wherein the plurality of protrusions are dot-shaped in a front view of the first side retainer and the second side retainer. 5 . The secondary battery according to claim 4 , wherein the plurality of protrusions have a shape selected from the group consisting of a cylindrical shape, a bent cylindrical shape, a conical shape, and a bent conical shape. 6 . The secondary battery according to claim 5 , wherein when the plurality of protrusions are in a curved shape, the ends of the plurality of protrusions face the cap assembly. 7 . The secondary battery according to claim 4 , wherein the plurality of protrusions are arranged in a plurality of rows and columns. 8 . The secondary battery according to claim 7 , wherein the plurality of protrusions in each of the plurality of rows and the plurality of columns are equally spaced apart from each other. 9 . The secondary battery according to claim 7 , wherein the number of the plurality of protrusions in each of the plurality of rows or the plurality of columns is equal. 10 . The secondary battery according to claim 7 , wherein the number of the plurality of protrusions in each of the plurality of rows or the plurality of columns is different. 11 . The secondary battery according to claim 1 , wherein the plurality of protrusions are linear in a front view of the first side retainer and the second side retainer. 12 . The secondary battery according to claim 11 , wherein the plurality of protrusions have a shape expanding left and right selected from the group consisting of a cylindrical shape, a bent cylindrical shape, a conical shape, and a bent conical shape. 13 . The secondary battery according to claim 12 , wherein when the plurality of protrusions are in a curved shape, the ends of the plurality of protrusions face the cap assembly. 14 . The secondary battery according to claim 11 , wherein the plurality of protrusions are arranged in a plurality of rows and in at least one column. 15 . The secondary battery according to claim 14 , wherein the plurality of protrusions in each of the plurality of rows or the at least one column are equally spaced apart from each other. 16 . The secondary battery according to claim 14 , wherein the plurality of protrusions are arranged in a plurality of columns, and wherein the number of the plurality of protrusions in each of the plurality of columns is equal. 17 . The secondary battery according to claim 16 , wherein the plurality of protrusions in each of the plurality of columns are symmetrical with the plurality of protrusions in an adjacent column of the plurality of columns. 18 . The secondary battery according to claim 1 , wherein the first and second side retainers are coupled to the first and second current collector plates, respectively, using an adhesive. 19 . The secondary battery according to claim 1 , wherein the first and second side retainers are coupled to the first and second current collector plates, respectively, by an interference fitting method.

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