Secondary battery and battery module having the same

Abstract

Provided are a secondary battery and a battery module having the same, the secondary battery including: a battery can having an opening for exposing an accommodation space, a can width in a first direction, and a can length in a second direction crossing the first direction; an electrode assembly in the accommodation space and including a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate; a cap assembly electrically connected to the positive electrode plate and the negative electrode plate and having a welding recess at an outer peripheral portion, the cap assembly being joined to a welding end of the battery can via the welding recess to seal the accommodation space; and a side welding portion joining a side portion of the welding end to a side portion of the cap assembly, a surface of the side welding portion being at the same level as or lower than a level of an outer peripheral surface of the battery can.

Description

Technical Field

[0001] Aspects of embodiments of the present disclosure relate to a secondary battery and a battery module including the secondary battery. Background Art

[0002] A secondary battery may have a structure in which a lid assembly is joined to an end of a battery can containing an electrode assembly to seal the interior of the battery can. An electrical connection between the electrode assembly and the external environment is established through electrode terminals provided in the lid assembly.

[0003] The lid assembly serves as a connection terminal for electrically connecting the external environment to the electrode assembly. Thus, surface non-uniformities of the lid assembly may result in non-uniform contact areas, which may cause connection failures in the battery module and connection failures in the packaging process of the battery.

[0004] The above information disclosed in this background art section is for enhancing understanding of the background art of the present disclosure, and thus, it may include information that does not constitute the prior art. Summary of the Invention

[0005] A lid assembly in which electrode terminals are provided may be coupled to a welding step provided on a battery can and may be coupled to the battery can by top surface welding. In this case, the weld bead may bulge upward, and the cross-section of the electrode may become non-uniform.

[0006] For example, in a secondary battery having a pair of side terminal structures in which lid assemblies are provided at each open end of a battery can to separately connect to a positive electrode and a negative electrode of an electrode assembly, surface non-uniformities caused by weld beads on the lid assemblies may cause connection failures at each of the positive electrode and the negative electrode.

[0007] Embodiments of the present disclosure may be directed to a secondary battery and / or a battery module including the secondary battery, the secondary battery including welding recesses at sides of the lid assembly and sides of the battery can.

[0008] Embodiments of the present disclosure may be directed to a secondary battery and / or a battery module including the secondary battery that has a uniform size after welding by including welding recesses between the battery can and the lid assembly.

[0009] The above and other aspects and features of the present disclosure will be described in the following description of some embodiments of the present disclosure, or will become more apparent through the following description of some embodiments of the present disclosure.

[0010] According to one or more embodiments of the present disclosure, a secondary battery includes: a battery can having an opening for exposing an accommodation space to the outside, a can width in a first direction, and a can length in a second direction intersecting the first direction; an electrode assembly disposed in the accommodation space and including a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate; a cover assembly electrically connected to the positive electrode plate and the negative electrode plate and having a welding recess at an outer peripheral portion thereof, the cover assembly being joined to a welding end of the battery can via the welding recess to seal the accommodation space; and a side welding portion joining a side portion of the welding end of the battery can to a side portion of the cover assembly, a surface of the side welding portion being at the same level as or lower than a level of an outer peripheral surface of the battery can.

[0011] In an embodiment, a width of the cover assembly in the first direction may be less than a width of the battery can in the first direction.

[0012] In an embodiment, the cover assembly may include: a body having a body front surface exposed to the outside, a body rear surface defining the accommodation space, and a first thickness in the second direction from the body front surface to the body rear surface; and a wing having a wing front surface flush with the body front surface, a wing rear surface defining the welding recess, and a second thickness in the second direction from the wing front surface to the wing rear surface, the second thickness being less than the first thickness.

[0013] In an embodiment, the welding recess may be defined by the wing rear surface and a body side surface connecting the wing rear surface and the body rear surface to each other, the welding recess may be configured to join the welding end to the wing rear surface and the body side surface, and a welding step may be located between a wing side surface of the wing and an outer peripheral surface of the welding end.

[0014] In an embodiment, the side welding portion may include: a welding portion joining the wing rear surface, the body side surface, and the welding end to each other; and a bead portion extending along the wing side surface from the welding portion and having a maximum thickness corresponding to a thickness of the welding step.

[0015] In an embodiment, a surface of the bead portion may be at the same level as or lower than a level of an outer peripheral surface of the welding end.

[0016] In an embodiment, the second thickness may be at least 50% and not greater than 80% of the first thickness.

[0017] In an embodiment, a width of the cover assembly in the first direction may be the same as a can width of the battery can in the first direction.

[0018] In an embodiment, the cover assembly may include: a main body having a front surface of the main body exposed to the outside, a rear surface of the main body defining an accommodation space, and a first thickness from the front surface of the main body to the rear surface of the main body in a second direction; and a wing having a front surface of the wing, a reduced rear surface of the wing, a bead rear surface of the wing, and a bead side surface of the wing. The front surface of the wing may be flush with the front surface of the main body. The reduced rear surface of the wing defines a welding recess. The bead side surface of the wing is connected to the bead rear surface of the wing and the reduced rear surface of the wing and has a stepped portion with respect to the side surface of the main body. The wing has a second thickness from the front surface of the wing to the reduced rear surface of the wing in the second direction and a third thickness from the front surface of the wing to the bead rear surface of the wing in the second direction. The second thickness is less than the first thickness, and the third thickness is less than the second thickness. The cover assembly may have a first side recess that is connected to communicate with the welding recess and is defined by the bead rear surface of the wing and the bead side surface of the wing.

[0019] In an embodiment, the welding end may include: a can bead side surface that may be stepped with respect to the outer peripheral surface and is located at the same level as the level of the bead side surface of the wing; and a can bead front surface that faces the bead rear surface of the wing in the second direction and is connected to the can bead side surface and the outer peripheral surface. The welding end may have a second side recess that is connected to communicate with the welding recess and the first side recess, and the second side recess is defined by the can bead side surface and the can bead front surface.

[0020] In an embodiment, the side welding portion may include: a welding portion that joins the reduced rear surface of the wing, the side surface of the main body, and the welding end to each other; and a bead portion that is connected to the welding portion and covers the bead side surface of the wing and the can bead side surface. The bead portion extends in a conical shape along the bead rear surface of the wing and the can bead front surface, and the tip of the bead portion may be located at a level lower than the levels of the wing side surface and the outer peripheral surface.

[0021] In an embodiment, the bead rear surface of the wing may have a first inclined surface extending from the edge of the wing side surface to the edge of the reduced rear surface of the wing, and the third thickness between the front surface of the wing and the bead rear surface of the wing may be variable along a first direction, and the can bead front surface may have a second inclined surface extending from the edge of the outer peripheral surface to the edge of the can bead side surface.

[0022] In an embodiment, the side welding portion may include: a welding portion that joins the reduced rear surface of the wing, the side surface of the main body, and the welding end to each other; and a bead portion including a base portion and a conical portion. The base portion has an increasing cross-sectional area along the first direction starting from the welding portion while contacting the first inclined surface and the second inclined surface, and the conical portion has a decreasing cross-sectional area along the first direction without contacting the first inclined surface and the second inclined surface. The top of the conical portion may be located at a level lower than the levels of the outer peripheral surface and the wing side surface.

[0023] In an embodiment, the openings may be located at each of the opposite ends of the battery can in the second direction, and the lid assembly may include a pair of side terminals at the opposite ends of the battery can to be electrically connected to the positive electrode plate and the negative electrode plate.

[0024] According to one or more embodiments of the present disclosure, a battery module includes: a plurality of battery cells, each battery cell including: a corresponding battery can configured to accommodate an electrode assembly and having a can width in a first direction and a can length in a second direction intersecting the first direction; and a corresponding lid assembly including electrode terminals and welded to an end of the corresponding battery can, the plurality of battery cells being aligned in rows in a third direction such that the battery cans of the battery cells face each other; a plurality of connection terminals on top surfaces of the plurality of battery cells and connected to the electrode terminals of the plurality of battery cells by connection wires connecting the electrode terminals to each other; a plurality of connection tabs connecting a group of the connection terminals among the connection terminals to each other to transmit electric energy; and a protection circuit connected to the plurality of connection tabs to protect the plurality of battery cells from overcurrent. Each of the plurality of battery cells further includes a side welding portion, a welded end of the corresponding battery can being received in a welding recess at a side of the corresponding lid assembly and welded to the side welding portion, the side welding portion having a surface located at a level the same as or lower than a level of an outer peripheral surface of the corresponding battery can.

[0025] In an embodiment, the corresponding lid assembly may include: a main body having a main body front surface exposed to the outside, a main body rear surface defining an accommodation space as an inner space of the corresponding battery can, and a first thickness in the second direction from the main body front surface to the main body rear surface; and a wing having a wing front surface that may be flush with the main body front surface, a wing rear surface defining the welding recess, and a second thickness in the second direction from the wing front surface to the wing rear surface, the second thickness being less than the first thickness.

[0026] In an embodiment, a width of the corresponding lid assembly may be less than the can width of the corresponding battery can, and the side welding portion may include: a welding portion joining the wing rear surface, the main body side surface, and the welded end to each other; and a bead portion extending along a wing side surface from the welding portion and having a maximum thickness corresponding to a thickness of the welding step portion.

[0027] In an embodiment, the corresponding lid assembly may include: a main body having a front surface of the main body exposed to the outside, a rear surface of the main body defining an accommodation space, and a first thickness from the front surface of the main body to the rear surface of the main body in a second direction; and having a front wing surface, a reduced rear wing surface, a bead rear wing surface, and a bead side wing surface, the front wing surface may be flush with the front surface of the main body, the reduced rear wing surface defines a welding recess, the bead side wing surface is connected to the bead rear wing surface and the reduced rear wing surface and has a step portion with respect to the side surface of the main body, the wing has a second thickness from the front wing surface to the reduced rear wing surface in the second direction and a third thickness from the front wing surface to the bead rear wing surface in the second direction, the second thickness is less than the first thickness, and the third thickness is less than the second thickness. The corresponding lid assembly may have a first side recess that is communicatively connected to the welding recess and is defined by the bead rear wing surface and the bead side wing surface. The welding end may include: a can bead side surface that is stepped with respect to the outer peripheral surface and is located at the same level as the bead side wing surface; and a can bead front surface that faces the bead rear wing surface in the second direction and is connected to the can bead side surface and the outer peripheral surface. The welding end may have a second side recess that is communicatively connected to the welding recess and the first side recess and is defined by the can bead side surface and the can bead front surface.

[0028] In an embodiment, the side welding portion may include: a welding portion that joins the reduced rear wing surface, the side surface of the main body, and the welding end to each other; and a bead portion that is connected to the welding portion and covers the bead side wing surface and the can bead side surface, the bead portion extends in a conical shape along the bead rear wing surface and the can bead front surface, and the tip of the bead portion may be located at a level lower than the level of the wing side surface and the outer peripheral surface.

[0029] In an embodiment, the corresponding lid assembly may include a pair of side terminals at opposite ends of the corresponding battery can to be electrically connected to the positive electrode plate and the negative electrode plate.

[0030] According to some embodiments of the present disclosure, a mating recess (e.g., a welding recess) may be formed in an integrally formed lid assembly manufactured by molding, rather than in a battery can integrally formed by a forging process such as deep drawing. Therefore, the lid assembly and the battery can may be joined by side welding without additional processing for the battery can. Thus, the stability and yield of the secondary battery may be improved.

[0031] In some embodiments, during the welding of the lid assembly and the battery can, the bead generated on the side wall may be located below the outer peripheral surface of the battery can to prevent or substantially prevent the bead from protruding to the outside of the battery can. Therefore, a uniform or substantially uniform width of the lid assembly may be maintained.

[0032] In some embodiments, by preventing or substantially preventing the weld bead from protruding onto the surface of the secondary battery, it may be possible to minimize or reduce the alignment complexity of the face-to-face alignment of adjacent battery cells in a battery module having secondary batteries arranged in rows, thereby increasing the density of the battery cells accommodated in a single housing.

[0033] However, aspects and features of the present disclosure are not limited to the aspects and features described above, and the above and other aspects and features will be partly set forth in the detailed description with reference to the drawings, and partly will be obvious therefrom, or may be learned by practicing one or more of the presented embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following and other aspects and features of the present disclosure will be more clearly understood from the following detailed description of illustrative, non-limiting embodiments with reference to the drawings, in which: Figure 1 is a perspective view showing a secondary battery according to an embodiment of the present disclosure; Figure 2 is a cross-sectional view of the secondary battery taken along the line a-a' shown in Figure 1 ; Figure 3 is a cross-sectional view of the secondary battery taken along the line b-b' shown in Figure 1 ; Figure 4 is a perspective view showing an electrode structure included in the secondary battery shown in Figure 1 ; Figure 5 shows an embodiment of a side welding unit included in the secondary battery shown in Figure 2 ; Figure 6 shows an embodiment of a side welding unit included in the secondary battery shown in Figure 2 ; Figure 7 shows an embodiment of a side welding unit included in the secondary battery shown in Figure 2 ; Figure 8 shows an embodiment of a side welding unit included in the secondary battery shown in Figure 2 ; and Figure 9 is a perspective view showing a battery module according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] In the following, embodiments will be described in more detail with reference to the accompanying drawings, in which the same reference numerals always denote the same elements. However, the present disclosure may be implemented in various different forms and should not be construed as limited to the embodiments shown herein. Instead, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art. Accordingly, processes, elements, and techniques that are not necessary for a person of ordinary skill in the art to fully understand the aspects and features of the present disclosure may not be described. Unless otherwise noted, throughout the drawings and the written description, the same reference numerals denote the same elements, and thus, redundant descriptions thereof may not be repeated.

[0036] When a certain embodiment can be implemented differently, the specific process order may be different from the described order. For example, two consecutively described processes may be performed simultaneously or substantially simultaneously, or may be performed in an order opposite to the described order.

[0037] In the drawings, for clarity, the relative dimensions, thicknesses, and ratios of elements, layers, and regions may be exaggerated and / or simplified. For ease of explanation, spatial relative terms such as "under", "below", "lower", "beneath", "above", "upper", etc. may be used herein to describe the relationship of one element or feature shown in the figures to another (other) element or feature. It will be understood that, in addition to the orientation depicted in the figures, spatial relative terms are also intended to cover different orientations of the device during use or operation. For example, if the device in the figures is flipped, an element described as "under", "below", or "beneath" other elements or features will then be oriented "above" the said other elements or features. Thus, the example terms "under" and "beneath" can cover both the upper and lower orientations. The device may be otherwise oriented (e.g., rotated 90 degrees or in other orientations), and the spatial relative descriptive terms used herein should be interpreted accordingly.

[0038] In the figures, the x-axis, y-axis, and z-axis are not limited to the three axes of a rectangular coordinate system and may be interpreted in a broader sense. For example, the x-axis, y-axis, and z-axis may be perpendicular to each other or substantially perpendicular to each other, or may represent different directions that are not perpendicular to each other.

[0039] Any numerical range disclosed and / or recited herein is intended to include all sub-ranges having the same numerical precision as that recited within the range. For example, a range of "1.0 to 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including the recited minimum value of 1.0 and the recited maximum value of 10.0), i.e., having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, by way of example, 2.4 to 7.6. Any maximum numerical limit recited herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit recited in this specification is intended to include all higher numerical limits contained therein.

[0040] Referring to two compared elements, features, etc. as "the same" can mean that they are "substantially the same". Thus, the phrase "substantially the same" can include cases having a deviation considered low in the art, such as, by way of example, a deviation of 5% or less. Additionally, when a certain parameter is said to be uniform in a given region, this can mean that it is uniform in terms of the average value.

[0041] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, without departing from the spirit and scope of the present disclosure, the first element, first component, first region, first layer, or first part described below may be referred to as the second element, second component, second region, second layer, or second part.

[0042] It will be understood that when an element or layer is referred to as being "on", "connected to", or "bonded to" another element or layer, it can be directly on, directly connected to, or directly bonded to the other element or layer, or there may be one or more intervening elements or layers. Similarly, when a layer, region, or element is referred to as being "electrically connected" to another layer, region, or element, it can be directly electrically connected to the other layer, region, or element, and / or it can be indirectly electrically connected to the other layer, region, or element with one or more intervening layers, regions, or elements therebetween. Additionally, it will also be understood that when an element or layer is referred to as being "between" two elements or layers, it can be the only element or layer between the two elements or layers, or there may also be one or more intervening elements or layers.

[0043] The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are also intended to include the plural forms. It will also be understood that when the terms "comprises", "comprising", "includes" and "including" and their variants are used in this specification, they specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. For example, the expression "A and / or B" means A, B, or A and B. When an expression such as "at least one of" is placed after a list of elements, it modifies the entire list of elements and not individual elements in the list. For example, the expressions "at least one of a, b or c", "at least one of a, b and c" and "at least one of the group consisting of a, b and c" indicate only a, only b, only c, both a and b, both a and c, both b and c, all of a, b and c, or variants thereof.

[0044] As used herein, the terms "substantially", "about" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art. Further, when describing embodiments of the disclosure, the use of "may" means "one or more embodiments of the disclosure". As used herein, the term "use" and its variants may be considered to be synonymous with the term "utilize" and its variants, respectively.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will also be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0046] Figure 1 is a perspective view showing a secondary battery according to an embodiment of the present disclosure. Figure 2 is along Figure 1 a cross-sectional view of the secondary battery taken along line a-a' shown in Figure 3 is along Figure 1 a cross-sectional view of the secondary battery taken along line b-b' shown in Figure 4 is a perspective view showing an electrode structure included in the Figure 1 secondary battery shown inFigure 5 illustrates an embodiment of a side welding unit included in the secondary battery shown in Figure 2 . Figure 6 illustrates an embodiment of a side welding unit included in the secondary battery shown in Figure 2 .

[0047] Hereinafter, a prismatic secondary battery will be mainly described as a representative example of the secondary battery. However, the present disclosure is not limited thereto, and as will be understood by those of ordinary skill in the art, the embodiments of the present disclosure described herein can also be applied to cylindrical secondary batteries.

[0048] Referring to Figures 1 to 6 , a secondary battery 500 according to one or more embodiments of the present disclosure may include a battery can 100 having an accommodation space therein, an electrode assembly EA accommodated in the accommodation space, a cap assembly 200 covering an end of the battery can 100 to seal the accommodation space, and a side welding unit (e.g., a side welding portion or a side welding part) 300 that joins a side portion of the cap assembly 200 and the battery can 100 to each other.

[0049] In an embodiment, the battery can 100 may be provided as a rectangular prism having at least one opening O (e.g., having at least one open end) at one end or at both ends of the battery can 100. The battery can 100 may have a can width (D can ) along the width direction (e.g., the first direction I) of the secondary battery 500 and a can length along the length direction (e.g., the second direction II) of the secondary battery 500.

[0050] For example, the battery can 100 may be provided as a three-dimensional structure formed by a single forging process to have an accommodation space therein, and the electrode assembly EA and the electrolyte may be accommodated in the accommodation space.

[0051] The accommodation space may be sealed from the outside by the cap assembly 200 that can be welded to the end of the battery can 100. Accordingly, the base plate of the cap assembly 200 and the battery can 100 may be made of the same or substantially the same material such that the accommodation space can be sufficiently sealed to improve welding quality. For example, the battery can 100 may be composed of aluminum or an aluminum alloy that may be a material having excellent electrical conductivity and ductility.

[0052] In an embodiment, the electrode assembly EA may be set to a wound structure in which a positive electrode plate A and a negative electrode plate C are wound after a separator S serving as an insulator is interposed therebetween. Each of the positive electrode plate A and the negative electrode plate C may include a coated portion and an uncoated portion. The coated portion is an area where an active material is coated onto a current collector including a metal foil (e.g., formed of a metal foil), and the uncoated portion is an area where the active material is not coated. The positive electrode plate A of the electrode assembly EA may be connected to the positive electrode lead plate 110 through the positive electrode uncoated portion. The negative electrode plate C may be connected to the negative electrode lead plate 120 through the negative electrode uncoated portion.

[0053] The positive electrode lead plate 110 may include or may be provided with a positive electrode connection plate 111, and a positive electrode terminal T1, which will be described in more detail below, is connected to the positive electrode connection plate 111. Additionally, the negative electrode lead plate 120 may include or may be provided with a negative electrode connection plate 112, and a negative electrode terminal T2, which will be described in more detail below, is connected to the negative electrode connection plate 112. The positive electrode terminal T1 and the negative electrode terminal T2 may be connected to an external load or power source.

[0054] The electrode assembly EA may be inserted into the accommodation space of the battery can 100 to form a chemical battery with an electrolyte solution. After the lid assembly 200 and the battery can 100 are sealed to each other by welding, the electrolyte solution is injected into the accommodation space through an injection hole. The electrolyte solution may perform ion exchange between the positive electrode plate A and the negative electrode plate C constituting the electrode assembly EA to generate a continuous current through the positive electrode terminal T1 and the negative electrode terminal T2, which will be described in more detail below.

[0055] In an embodiment, the lid assembly 200 may be set to have a lid width D that is smaller than the can width D in a first direction I can of a flat or substantially flat plate structure. The lid assembly 200 may include a flat or substantially flat plate containing a conductive metal (e.g., made of a conductive metal), a conductive member for electrically connecting the electrode terminal T to the electrode assembly EA, and an insulating member. cap In the present embodiment, the lid assembly 200 may be set to be connected to (e.g., bonded to or attached to) the end of the battery can 100 by welding to seal the electrode terminal T of the accommodation space of the battery can 100.

[0056] More specifically, when the battery can 100 is an open-type prism with both ends (e.g., opposite ends) open, two lid assemblies 200 may be set to be respectively connected (e.g., bonded or attached) to a pair of side terminals at opposite ends of the battery can 100 by welding.

[0057]

[0058] ​In other words, the side terminals may respectively include a positive terminal T1 and a negative terminal T2. The positive terminal T1 is the electrode terminal T connected to the positive electrode plate A, and the negative terminal T2 is the electrode terminal T connected to the negative electrode plate C.

[0059] For example, the cover assembly 200 may include a main body 210 and wings 220. The main body 210 may be provided in a plate shape having a first thickness t1 along a second direction II which is the longitudinal direction of the secondary battery 500. In addition, the main body 210 may be a structure that electrically connects the electrode terminal T and the electrode assembly EA to each other.

[0060] The main body 210 is provided as a cover that covers the opening O of the battery can 100 at the central portion of the cover assembly 200 to seal the accommodation space which is the internal space of the battery can 100 from the outside. Accordingly, the front surface 211 of the main body (e.g., the front surface of the main body 210) is exposed to the outside, while the rear surface 212 of the main body (e.g., the rear surface of the main body 210) facing away from the front surface 211 of the main body faces the accommodation space. In other words, the main body 210 is inserted into the opening O of the battery can 100 to define the internal accommodation space, and extends from the front surface 211 of the main body to the rear surface 212 of the main body along the second direction II with the first thickness t1.

[0061] The wings 220 may be plate-like structures extending from the sides of the flat or substantially flat plate constituting the main body 210. The wings 220 may not be provided with a structure for electrically connecting the electrode terminal T and the electrode assembly EA to each other. For example, the wings 220 may include a front surface 221 of the wing (e.g., the front surface of the wing 220) flush with the front surface 211 of the main body and a rear surface 222 of the wing (e.g., the rear surface of the wing 220) defining a welding recess WR. The wings 220 may extend from the front surface 221 of the wing to the rear surface 222 of the wing along the second direction II with a second thickness t2 smaller than the first thickness t1.

[0062] Accordingly, the rear surface 222 of the wing may be stepped with respect to the rear surface 212 of the main body, such that the space provided below the rear surface 222 of the wing (e.g., at the rear side of the rear surface 222 of the wing) may be provided as the welding recess WR, and the cover assembly 200 and the battery can 100 are joined to each other by welding at the welding recess WR. The welding recess WR may be defined by a main body side surface 213 (e.g., the side surface of the main body 210) constituting the stepped portion between the rear surface 222 of the wing and the rear surface 212 of the main body and the rear surface 222 of the wing. A welding end WE of the battery can 100 connected to (e.g., joined to or attached to) the end of the welding recess WR contacts the rear surface 222 of the wing and the main body side surface 213 when the welding end WE is welded. The welding recess WR may be formed continuously or substantially continuously along the periphery of the cover assembly 200 to continuously or substantially continuously join the welding end WE of the battery can 100.

[0063] In the present embodiment, the second thickness t2 may be about 50% to about 80% of the first thickness t1. In the case where the second thickness t2 is less than 50% of the first thickness t1, it may be difficult to sufficiently support the battery can 100 accommodated in the welding recess WR, or damage to the wing 220 may occur during welding, which increases the welding difficulty. In the case where the second thickness t2 is greater than 80% of the first thickness t1, the size of the welding recess WR may be insufficient, which results in poor welding joint strength and poor support for the battery can 100. Therefore, the second thickness t2 may be about 50% to about 80% of the first thickness t1.

[0064] The wing 220 and the main body 210 may include one or more materials that minimize or reduce the formation of beads while considering welding parameters (e.g., may be made of one or more materials that minimize or reduce the formation of beads while considering welding parameters). In the present embodiment, the main body side surface 213 and the lower part (e.g., rear part) of the main body 210 adjacent to the main body side surface 213 may each include aluminum and / or an aluminum alloy (e.g., may equivalently be made of aluminum and / or an aluminum alloy). The cover assembly 200 and the battery can 100 may be joined to each other at the welding recess WR by the side welding unit 300 to provide a single secondary battery 500.

[0065] For example, the side welding unit 300 may join the wing 220 and the welding end WE together at the side of the secondary battery 500, and may be disposed at a level lower than the level of the outer circumferential surface 101 of the battery can 100 to prevent or substantially prevent an increase in the width of the secondary battery 500.

[0066] In the present embodiment, the side welding unit 300 may include a welding part 310 that joins the wing 220, the main body 210, and the welding end WE together by welding, and a weld bead part 320 that extends from the welding part 310 to the outside of the welding recess WR.

[0067] The welding part 310 may join the wing 220, the main body 210, and the welding end WE to each other by welding, melting, and cooling to integrally join the cover assembly 200 and the battery can 100 to each other. In the present embodiment, the wing 220, the main body 210, and the welding end WE may be joined to each other by laser welding. However, the present disclosure is not limited thereto, and various suitable types of welding processes may be utilized as long as the wing 220, the main body 210, and the welding end WE are welded to each other without damaging other components of the cover assembly 200.

[0068] Since the molten weld base metal of the wing 220, the main body 210, and the welding end WE flows and solidifies along a contour corresponding to a flow surface (e.g., the flow surface defined by the welding recess WR) during welding, the bead portion 320 forms the uppermost portion of the welded portion 310. In this case, the bead portion 320 may be formed in a boundary region that is a welding point between the wing side surface 223 and the outer peripheral surface 101 of the battery can 100, and the bead portion 320 may grow along the wing side surface 223 that is the side surface of the wing 220.

[0069] Cover width D cap Less than the can width D can , such that a welding step WS is formed at a boundary region between the battery can 100 and the cover assembly 200. In other words, the wing side surface 223 is positioned lower than the outer peripheral surface 101 of the battery can 100, such that the welding step WS is formed between the wing side surface 223 and the outer peripheral surface 101. Thus, by providing the welding step WS, the initial bead growth toward the battery can 100 (e.g., growth along the outer peripheral surface 101) can be suppressed.

[0070] Furthermore, the welding process can be controlled such that the bead portion 320 is formed to have a thickness less than or equal to the thickness of the welding step WS between the wing side surface 223 and the outer peripheral surface 101, thereby preventing or substantially preventing the bead portion 320 from growing beyond the welding step WS onto the battery can 100. For example, the thickness of the bead portion 320 can be determined by considering various factors such as the viscosity of the molten metal used during welding, the solidification time, the volume expansion rate, and / or the welding completion characteristics. By adjusting one or more of the welding parameters, the molten metal can flow sufficiently along the wing side surface 223 to form the welded portion 310 by solidification, while allowing the maximum thickness of the bead portion 320 in the first direction I to correspond to the thickness of the welding step WS. Thus, the surface of the bead portion 320 can be positioned Figure 5 at the same level or substantially the same level as the outer peripheral surface 101 of the battery can 100 as shown in Figure 6 or at a level lower than the level of the outer peripheral surface 101 of the battery can 100 as shown in

[0071] Therefore, by controlling the welding parameters to ensure that the surface of the bead portion 320 is not positioned higher than the outer peripheral surface 101, the bead portion 320 can be formed such that the side welding unit 300 is prevented or substantially prevented from protruding above the outer peripheral surface 101 of the battery can 100. Thus, the outer peripheral surface 101 of the secondary battery 500 can be prevented from becoming uneven during a side welding process (e.g., a transverse welding process) that joins the battery can 100 and the cover assembly 200 to each other.

[0072] Figure 7 Shows including inFigure 2 An embodiment of a side welding unit in a secondary battery as shown.

[0073] Referring to Figure 7 , the lid assembly 200 and the battery can 100 can have the same or substantially the same width as each other, such that the wing side surface 223 and the outer peripheral surface 101 can be positioned at the same or substantially the same level as each other. In other words, the lid width D cap and the can width D can (e.g., see Figure 2 ) can be the same or substantially the same as each other. In this case, the lid assembly 200 can include (e.g., can have) additional side recesses (e.g., lateral side recesses) SR to accommodate the first side welding unit (e.g., the first side weld or the first side weld portion) 301 while preventing or substantially preventing the first side welding unit 301 from protruding from the outer peripheral surface 101.

[0074] For example, the lid assembly 200 can include a main body 210 and a wing 220. The main body 210 has a main body front surface 211 and a main body rear surface 212, and the main body 210 has a first thickness t1 between the main body front surface 211 and the main body rear surface 212. The wing 220 has two stepped portions to provide a first side recess SR1 communicating with the welding recess WR. For example, the wing 220 can include a wing front surface 221 flush with the main body front surface 211 and a wing reduced rear surface 222' (e.g., the reduced rear surface of the wing 220). The wing reduced rear surface 222' is positioned to define (e.g., delimit) the welding recess WR, and the wing 220 can have a second thickness t2 less than the first thickness t1 along a second direction II from the wing front surface 221 to the wing reduced rear surface 222'. The wing 220 can also include a wing weld bead rear surface 222a and a wing weld bead side surface 223a. The wing weld bead side surface 223a is connected to the wing weld bead rear surface 222a and the wing reduced rear surface 222' and has a stepped portion with respect to the main body side surface 213, and the wing 220 can have a third thickness t3 smaller than the second thickness t2 along the second direction II from the wing front surface 221 to the wing weld bead rear surface 222a.

[0075] In other words, by removing a portion of the wing 220 adjacent to the welding end WE, the lid assembly 200 can also provide a first side recess SR1 connected to the welding recess WR and defined by the wing weld bead rear surface 222a and the wing weld bead side surface 223a. In this case, the second thickness t2 can be at least 50% of the first thickness t1 and not greater than 80% of the first thickness t1, and the third thickness t3 can be at least 50% of the second thickness t2 and not greater than 80% of the second thickness t2. Therefore, the welding support of the wing 220 with two stepped portions can be sufficiently ensured.

[0076] Similarly, by removing the portion of the welding end WE adjacent to the wing 220, the battery can 100 can include (e.g., can be provided with) a can weld bead side surface 102 and a can weld bead front surface 103. The can weld bead side surface 102 is stepped with respect to the outer peripheral surface 101 and is positioned at the same or substantially the same level as the wing weld bead side surface 223a. The can weld bead front surface 103 is positioned to face (e.g., oppose) the wing weld bead rear surface 222a in the second direction II and is connected to the can weld bead side surface 102 and the outer peripheral surface 101, thereby forming a welding end (e.g., a stepped welding end) WE'. In other words, by removing the portion of the welding end WE adjacent to the wing 220, the battery can 100 can include a second side recess SR2 that is connected to the welding recess WR and is defined by the can weld bead side surface 102 and the can weld bead front surface 103 to form the welding end WE'.

[0077] Accordingly, a side recess SR that communicates with the welding recess WR and includes the first side recess SR1 and the second side recess SR2 can be provided in the boundary region between the lid assembly 200 and the battery can 100.

[0078] In this case, the first side welding unit 301 can be received in the side recess SR, thereby preventing the first side welding unit 301 from protruding higher than the wing side surface 223 or the outer peripheral surface 101 of the battery can 100. The lid assembly 200 and the battery can 100 can be integrally joined to each other by the first side welding unit 301 provided in the side recess SR.

[0079] The first side welding unit 301 can include a first welding portion 311 that joins the reduced wing rear surface 222', the main body side surface 213, and the welding end WE' to each other by welding and a conical first weld bead portion 321 that extends from the first welding portion 311.

[0080] In addition to having a reduced height, the first welding portion 311 has the same or substantially the same configuration as the welding portion 310 described above with reference to Figure 5 and Figure 6 Therefore, redundant description of the first welding portion 311 can be omitted.

[0081] The first weld bead portion 321 can be connected to the first welding portion 311, can cover the wing weld bead side surface 223a and the can weld bead side surface 102, and can extend in a conical shape along the wing weld bead rear surface 222a and the can weld bead front surface 103. The tip of the first weld bead portion 321 can be positioned at a level lower than the levels of the wing side surface 223 and the outer peripheral surface 101.

[0082] Compared with the length of the welding part 310 described above, the first welding part 311 may have a reduced length, which can achieve a reduced welding area. In addition, the first bead part 321 may grow upward from the first welding part 311 to have a smaller cross-sectional area, thereby forming a conical shape within the side recess SR.

[0083] Therefore, the first bead part 321 may grow in the first direction I along the wing bead rear surface 222a and the can bead front surface 103 while covering the bottom constituting the side recess SR and defining the wing bead side surface 223a and the can bead side surface 102 of the side recess SR.

[0084] The bead may grow most actively in the central part communicating with the welding recess WR and may grow relatively slowly toward the wing bead rear surface 222a and the can bead front surface 103 located at the periphery of the welding recess WR, such that the conical first bead part 321 may be formed.

[0085] In the present embodiment, the wing bead rear surface 222a and the can bead front surface 103 have the same or substantially the same recess depth from each other, while the wing bead side surface 223a and the can bead side surface 102 are provided at the same or substantially the same level from each other, such that the side recess SR may have a rectangular cross-sectional shape.

[0086] In the present embodiment, the welding area at the wing reduced rear surface 222' is reduced by the side recess SR, but this may be offset by the increased welding area at the wing bead side surface 223a and the can bead side surface 102. Therefore, the first bead part 321 may be accommodated in the side recess SR, but the bonding strength of the first welding part 311 may be maintained or substantially maintained intact. Accordingly, in the case where the lid assembly 200 and the battery can 100 are located at a single level without any stepped portions, the side recess SR may be formed to accommodate the first bead part 321 to prevent or substantially prevent the first side welding unit 301 from protruding from the surface of the secondary battery 500.

[0087] In the present embodiment, the side recess SR has a rectangular cross-sectional shape, but the present disclosure is not limited thereto, and the side recess SR may have various suitable shapes as long as it can accommodate the first side welding unit 301.

[0088] Figure 8 Illustrated is Figure 2 an embodiment of the side welding unit in the secondary battery shown in

[0089] Referring to Figure 8 , the lid assembly 200 may include a side recess SR', and the second side welding unit (e.g., the second side welding part or the second side welding portion) 302 may be formed along the shape of the side recess SR' and provided at the side recess SR'.

[0090] The adjacent portions of the fin 220 and the welding end WE' can be removed to be inclined away from each other symmetrically or substantially symmetrically, such that the fin weld bead rear surface 222a and the can weld bead front surface 103 described above with reference to Figure 7 can be respectively formed with a first inclined surface 224 and a second inclined surface 104. Accordingly, the side recess SR' can be provided on a side of the lid assembly 200 communicating with the welding recess WR, and can be defined by the first inclined surface 224 and the second inclined surface 104.

[0091] In this case, the first inclined surface 224 can extend from the edge of the fin side surface 223 to the edge of the fin-reduced rear surface 222', such that the third thickness t3 can be variable along the first direction I. In addition, the second inclined surface 104 can extend from the edge of the outer peripheral surface 101 to the edge of the surface of the welding end WE' facing the fin-reduced rear surface 222'. In some embodiments, the second inclined surface 104 can extend from the edge of the outer peripheral surface 101 to Figure 7 the edge of the can weld bead side surface 102 shown in. Accordingly, the side recess SR' can have a trapezoidal cross-sectional shape recessed inwardly from the outer peripheral surface 101 and the fin side surface 223. In this case, the second side welding unit 302 can include a second welding portion 312 and a second weld bead portion 322 extending from the second welding portion 312.

[0092] The second welding portion 312 joins the fin-reduced rear surface 222', the body side surface 213, and the reduced welding end WE' to each other by welding. The second welding portion 312 has the same or substantially the same configuration as the first welding portion 311 described above with reference to Figure 7 . Accordingly, redundant description of the second welding portion 312 will not be repeated.

[0093] The second weld bead portion 322 can be received in the side recess SR', and can extend conically from the second welding portion 312 along the first inclined surface 224 and the second inclined surface 104. The top of the second weld bead portion 322 can be lower than the outer peripheral surface 101 and the fin side surface 223.

[0094] Except that the welding surface is inclined, the second bead portion 322 has the same or substantially the same configuration as the first bead portion 321. Accordingly, redundant description of the second bead portion 322 may not be repeated. The second bead portion 322 may grow in a manner that increases the cross-sectional area until an inflection point set by the welding process conditions, and then may grow upward in a manner that decreases the cross-sectional area after the inflection point. Accordingly, the second bead portion 322 may include a base portion 322b and a conical portion 322a. The base portion 322b increases the cross-sectional area (e.g., the cross-sectional area in the plane defined by the second direction II and the third direction III or the cross-sectional area in the plane perpendicular to the growth direction) along the first direction I while contacting the first inclined surface 224 and the second inclined surface 104 until reaching the inflection point, and the conical portion 322a decreases the cross-sectional area (e.g., the cross-sectional area in the plane defined by the second direction II and the third direction III or the cross-sectional area in the plane perpendicular to the growth direction) along the first direction I from the inflection point without contacting the first inclined surface 224 and the second inclined surface 104.

[0095] In this case, the top of the conical portion 322a may be received in the side recess SR' to be positioned at a level lower than the levels of the outer circumferential surface 101 and the wing side surface 223, thereby preventing or substantially preventing the second side welding unit 302 from protruding from the surface of the secondary battery 500.

[0096] Although the present embodiment shows the cover assembly 200 and the battery can 100 having a prismatic cross-section, the present disclosure is not limited thereto, and various suitable shapes (such as a cylindrical shape) may be adopted as long as a cover capable of hermetically sealing an opening communicating with the outside of an open cylindrical structure can be welded.

[0097] Accordingly, as described above, the cover assembly 200 and the battery can 100 according to various embodiments of the present disclosure may be joined to each other at the side surface of the secondary battery 500 by any one of the side welding unit 300, the first side welding unit 301, and the second side welding unit 302.

[0098] In addition, the electrode assembly EA accommodated in the battery can 100 and the separately provided positive electrode terminal P and negative electrode terminal N may be reliably positioned.

[0099] In some embodiments, the secondary battery 500 may include a lithium ion battery. However, the present disclosure is not limited thereto, and the secondary battery 500 may include various suitable types of secondary batteries as long as the cover assembly can be used as an electrode terminal.

[0100] According to some embodiments of the present disclosure, instead of forming a stepped portion at the end of the battery can 100, a stepped portion is formed at the outer peripheral portion of the lid assembly 200 to allow the battery can 100 to be inserted into the welding recess WR and joined to the welding recess WR. Therefore, there is no need to form joining stepped portions for both the end of the battery can 100 and the end of the lid assembly 200 to join the battery can 100 and the lid assembly 200.

[0101] Since the battery can 100 can be formed by a continuous single molding process, the step of forming the joining stepped portion at the welding end WE would use an additional process for the battery can 100, which may reduce the manufacturing process efficiency of the secondary battery 500.

[0102] On the other hand, the secondary battery 500 according to some embodiments of the present disclosure can simplify the manufacturing process of the secondary battery 500 and improve the manufacturing process efficiency by forming the joining stepped portion on the lid assembly 200 formed by a molding process rather than on the battery can 100.

[0103] According to some embodiments of the present disclosure as described above, by forming the welding end on the lid assembly 200 formed by a molding process, the additional process for forming the welding end on the battery can 100 can be omitted. Therefore, the manufacturing process of the secondary battery 500 can be simplified, and the yield rate can be improved, thereby improving the process efficiency.

[0104] According to some embodiments of the present disclosure as described above, the side welding unit 300, the first side welding unit 301, and the second side welding unit 302 can be configured not to protrude from the outer peripheral surface 101 of the battery can 100 to maintain the uniform width of the secondary battery 500. Therefore, it is possible to prevent the standardization of the size of the secondary battery 500 from being damaged by the side welding.

[0105] Figure 9 is a perspective view showing a battery module according to an embodiment of the present disclosure.

[0106] Figure 9 The battery module 2000 shown in may include a plurality of battery cells that are the same as or substantially the same as the secondary battery 500 described above with reference to Figures 1 to 8 Therefore, in the Figure 9 In the battery module 2000 shown in, the same or similar reference numerals denote the same or similar components as those described above with reference to Figures 1 to 8 Therefore, their redundant descriptions may not be repeated.

[0107] Refer to Figure 9, according to an embodiment of the present disclosure, the battery module 2000 may include a plurality of battery cells 1000, and each battery cell 1000 includes a first connection terminal 131 and a second connection terminal 132. The battery cells 1000 may be arranged along one direction. A plurality of connection tabs 1100 may connect adjacent battery cells 1001 and 1002 to each other, and a protection circuit unit (e.g., a protection circuit) 1200 may be connected to the plurality of connection tabs 1100 to protect the battery cells 1000 from overcurrent.

[0108] For example, each battery cell 1000 may include a secondary battery 500 having the configuration described above with reference to Figures 1 to 8 Therefore, the battery cell 1000 may generate current through the electrochemical reaction of the electrode assembly EA and the electrolyte solution accommodated in the battery can 100.

[0109] More specifically, the battery cell 1000 may have a side terminal structure in which the cover assembly 200 is provided at the opposite end of the battery can 100 in the second direction II. Accordingly, the positive terminal and the negative terminal may be provided at each corresponding end of the battery cell 1000.

[0110] The battery cells 1000 are arranged such that the wider outer surfaces of adjacent battery cans 100 are in contact with each other in the third direction III, a pair of cover assemblies 200 are provided at the opposite ends of each battery can 100 in the second direction II, and the cover assemblies 200 are aligned in the third direction III.

[0111] The positive terminal T1 is connected to the first connection terminal 131 through a first connection wire extending upward, and the negative terminal T2 is connected to the second connection terminal 132 through a second connection wire 133 extending upward. Accordingly, the positive terminal T1 and the negative terminal T2 located on the side surface of the battery cell 1000 are respectively connected to the first connection terminal 131 and the second connection terminal 132 located on the top of the battery cell 1000 through the first connection wire and the second connection wire 133.

[0112] In this case, the plurality of first connection terminals 131 and the plurality of second connection terminals 132 may be electrically connected to the connection tabs 1100. A plurality of battery cells 1000 connected to a single connection tab 1100 through the first connection terminal 131 or the second connection terminal 132 may be used as a group of cells connected in parallel with each other.

[0113] In other words, a plurality of battery cells 1000 connected to the connection tabs 1100 may be connected in parallel with each other, and the connection tabs 1100 may be connected in series with each other such that the unit groups connected by the connection tabs 1100 are connected in series with each other.

[0114] Therefore, by adjusting the number of unit groups connected to the connection tab 1100, multiple battery cells 1000 can be electrically connected in a desired combination of series connection and parallel connection to form a battery module 2000.

[0115] The gas generated during the operation of the multiple battery cells 1000 can be discharged to the outside via the exhaust port 134.

[0116] The number and arrangement of the battery cells 1000 forming the battery module 2000 are not limited to Figure 9 the number and arrangement shown in

[0117] The multiple battery cells 1000 can be arranged in one direction with their relatively wide outer peripheral surfaces 101 facing each other, and the arranged multiple battery cells 1000 can be fixed by the module housing 1300.

[0118] In this case, the battery cells 1000 are arranged such that side welding units (e.g., side welding portions or side welding parts) 300 are provided on the sides of the battery cells 1000, while the surfaces of the side welding units 300 are positioned lower than the outer peripheral surfaces of the battery cells 1000. Therefore, the surfaces of the side welding units 300 are positioned at a level lower than the level of the outer peripheral surface 101 of the battery can 100 forming the battery cell 1000. Accordingly, it is possible to prevent or substantially prevent the side welding units 300 from protruding outward from the battery can 100.

[0119] As a result, the battery cells 1000 can be arranged to conform to the desired design dimensions such that their relatively wide surfaces can easily face each other.

[0120] The module housing 1300 can include a pair of end plates 1310 and 1320 provided at the front and rear of the aligned battery cells 1000 to face the relatively wide surfaces of the battery cells 1000, and side plates 1330 and a bottom plate 1340 connecting the pair of end plates 1310 and 1320 to each other.

[0121] The side plates 1330 can be provided in pairs to support both sides of the multiple battery cells 1000 concurrently or substantially simultaneously, and the bottom plate 1340 can be provided to support the bottom surfaces of the multiple battery cells 1000 concurrently or substantially simultaneously. The components of the module housing 1300 can be connected to each other by coupling members such as bolts B.

[0122] The protection circuit unit 1200 can include electronic devices, protection circuits, etc., and can be electrically connected to the connection tab 1100. The protection circuit unit 1200 includes a first circuit unit (e.g., first circuit) 1210 and a second circuit unit (e.g., second circuit) 1220 extending at different positions along the direction in which the multiple battery cells 1000 are arranged.

[0123] In this case, the first circuit unit 1210 and the second circuit unit 1220 may be spaced apart from each other and may be positioned parallel or substantially parallel to each other such that each of the first circuit unit 1210 and the second circuit unit 1220 is electrically connected to a corresponding adjacent connection tab 1100.

[0124] For example, the first circuit unit 1210 extends at an upper first side of the plurality of battery cells 1000 along a direction in which the plurality of battery cells 1000 are arranged, and the second circuit unit 1220 extends at an upper second side of the plurality of battery cells 1000 along a direction in which the plurality of battery cells 1000 are arranged. In this case, the second circuit unit 1220 may be spaced apart from the first circuit unit 1210 by a suitable distance (e.g., a certain or predetermined distance) and the exhaust port 134 is located therebetween, and may be arranged parallel or substantially parallel to the first circuit unit 1210.

[0125] A pair of circuit units 1210 and 1220 may be arranged side by side with each other, and may be spaced apart from each other and extend along a direction in which the plurality of battery cells are arranged, thereby minimizing or reducing an area of a printed circuit board (PCB) forming the protection circuit unit 1200.

[0126] Detection lines 1400 may be provided to detect a voltage, a temperature, and a current of each battery cell 1000, thereby verifying a normal operation of each battery cell 1000. In addition, if an abnormal operation occurs, the detection lines 1400 may send a stop signal that can stop the operation of a faulty unit.

[0127] First operation information including a voltage, a current, a temperature, etc., sent from the first circuit unit 1210 and the connection tab 1100 adjacent to the first circuit unit 1210 and second operation information including a voltage, a current, a temperature, etc., sent from the second circuit unit 1220 and the connection tab 1100 adjacent to the second circuit unit 1220 may be integrally managed through the detection lines 1400.

[0128] For example, the detection lines 1400 may include a flexible material (e.g., may be made of a flexible material), thus allowing the detection lines 1400 to flexibly adapt to the shape and structure of the surrounding environment.

[0129] More specifically, if swelling occurs in the battery cell 1000, the elasticity or flexibility of the detection lines 1400 may absorb shock and prevent or substantially prevent damage to the first circuit unit 1210 and the second circuit unit 1220.

[0130] In the present embodiment, the protection circuit unit 1200 may include a battery management system (BMS), and the connection tabs 1100 may include bus bars.

[0131] According to the battery module 2000 described above, the cover assembly 200 of the battery cell 1000 and the battery can 100 can be joined to each other by welding at the side of the battery cell 1000, and the side welding unit 300 can be positioned below the outer peripheral surface 101 of the battery can 100 so that the side welding unit 300 does not protrude to the outside of the battery can 100. Accordingly, adjacent battery cells 1000 can be reliably aligned face to face with each other.

[0132] According to some embodiments described above, the joining recess (e.g., welding recess) may not be formed in the battery can integrally formed by a forging process such as deep drawing, but may be formed in the cover assembly as a cover assembly structure manufactured by molding. Accordingly, the cover assembly and the battery can can be joined to each other by side welding without additional processing for the battery can. Accordingly, the stability and the yield of the secondary battery can be improved.

[0133] According to one or more embodiments of the present disclosure, during welding of the cover assembly and the battery can, the bead generated on the side wall may be located below the outer peripheral surface of the battery can to prevent or substantially prevent the bead from protruding to the outside of the battery can. Accordingly, the uniform width of the cover assembly can be maintained.

[0134] According to one or more embodiments of the present disclosure, by preventing the bead from protruding onto the surface of the secondary battery, it is possible to minimize or reduce the alignment complexity in the face-to-face alignment of adjacent battery cells in a battery module having secondary batteries arranged along a row, thereby increasing the density of the battery cells accommodated in a single case.

[0135] The foregoing is an illustration of some embodiments of the present disclosure and is not to be construed as a limitation thereof. Although some embodiments have been described, it will be readily understood by those skilled in the art that various modifications to the embodiments are possible without departing from the spirit and scope of the present disclosure. It will be understood that, unless otherwise described, the description of features or aspects within each embodiment is generally to be considered available for other similar features or aspects in other embodiments. Accordingly, it will be apparent to those of ordinary skill in the art that, unless otherwise expressly stated, the features, characteristics, and / or elements described in connection with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments. Accordingly, it will be understood that the foregoing is an illustration of various example embodiments and is not to be construed as limited to the specific embodiments disclosed herein, and that various modifications to the disclosed embodiments as well as other example embodiments are intended to be included within the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A secondary battery, comprising: a battery can having an opening for exposing the accommodation space to the outside, a can width in a first direction, and a can length in a second direction intersecting the first direction; an electrode assembly in the accommodation space and including a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate; a cap assembly electrically connected to the positive electrode plate and the negative electrode plate and having a welding recess at an outer peripheral portion of the cap assembly, the cap assembly being joined to a welding end of the battery can via the welding recess to seal the accommodation space; as well as A side welding portion joins the side of the welding end of the battery can to the side of the cap assembly, and the surface of the side welding portion is located at the same level as or lower than the level of the outer peripheral surface of the battery can.

2. The secondary battery according to claim 1, wherein A width of the cap assembly in the first direction is smaller than a width of the battery can in the first direction.

3. The secondary battery according to claim 2, wherein: The cover assembly comprises: a main body having a main body front surface exposed to the outside, a main body rear surface defining the accommodation space, and a first thickness from the main body front surface to the main body rear surface in the second direction; and A wing has a wing front surface flush with the main body front surface, a wing rear surface defining the welding recess, and a second thickness from the wing front surface to the wing rear surface in the second direction, the second thickness being less than the first thickness.

4. The secondary battery according to claim 3, wherein The welding recess is defined by the wing rear surface and a main body side surface connecting the wing rear surface and the main body rear surface to each other, wherein the welding recess is configured to join the welding end to the wing rear surface and the body side surface, and The welding step is located between the wing side surface of the wing and the outer peripheral surface of the welding end.

5. The secondary battery according to claim 4, wherein The side welding portion comprises: a welding portion that joins the wing rear surface, the main body side surface, and the welding end to each other; and A weld bead portion extends from the weld portion along the wing side surface and has a maximum thickness corresponding to a thickness of the weld step.

6. The secondary battery according to claim 5, wherein The surface of the weld bead portion is located at the same level as or at a level lower than that of the outer peripheral surface of the weld end.

7. The secondary battery according to claim 3, wherein: The second thickness is at least 50% and no more than 80% of the first thickness.

8. The secondary battery according to claim 1, wherein A width of the cap assembly in the first direction is the same as a can width of the battery can in the first direction.

9. The secondary battery according to claim 8, wherein The cover assembly comprises: a main body having a main body front surface exposed to the outside, a main body rear surface defining the accommodation space, and a first thickness from the main body front surface to the main body rear surface in the second direction; and A wing having a wing front surface, a wing reduced rear surface, a wing weld bead rear surface and a wing weld bead side surface, wherein the wing front surface is flush with the main body front surface, the wing reduced rear surface defines the welding recess, the wing weld bead side surface is connected to the wing weld bead rear surface and the wing reduced rear surface and has a step portion relative to the main body side surface, the wing having a second thickness from the wing front surface to the wing reduced rear surface in the second direction and a third thickness from the wing front surface to the wing weld bead rear surface in the second direction, the second thickness is less than the first thickness, the third thickness is less than the second thickness, and The cover assembly has a first side recessed portion which is communicatively connected to the welding recessed portion and is defined by the rear surface of the wing weld bead and the side surface of the wing weld bead.

10. The secondary battery according to claim 9, wherein The welding end comprises: a tank bead side surface that is stepped relative to the outer peripheral surface and is located at the same level as that of the wing bead side surface; and a tank bead front surface facing the wing bead rear surface in the second direction and connected to the tank bead side surface and the outer peripheral surface, and The welding end has a second side recessed portion communicatively connected to the welding recessed portion and the first side recessed portion, and the second side recessed portion is defined by the tank weld bead side surface and the tank weld bead front surface.

11. The secondary battery according to claim 10, wherein The side welding portion comprises: a welding portion that joins the wing reduced rear surface, the main body side surface, and the welding end to each other; and A weld bead portion is connected to the welding portion and covers the wing bead side surface and the tank bead side surface, the weld bead portion extends in a conical shape along the wing bead rear surface and the tank bead front surface, and the tip of the weld bead portion is located at a level lower than that of the wing side surface and the outer peripheral surface.

12. The secondary battery according to claim 10, wherein The wing bead rear surface has a first inclined surface extending from an edge of the wing side surface to an edge of the wing reduction rear surface, and the third thickness between the wing front surface and the wing bead rear surface is variable along the first direction, and The tank bead front surface has a second inclined surface extending from an edge of the outer peripheral surface to an edge of the tank bead side surface.

13. The secondary battery according to claim 12, wherein: The side welding portion comprises: a welding portion that joins the wing reduced rear surface, the main body side surface, and the welding end to each other; and a weld bead portion including a base portion and a conical portion, the base portion having an increased cross-sectional area along the first direction from the weld portion while in contact with the first inclined surface and the second inclined surface, the conical portion having a reduced cross-sectional area along the first direction while not in contact with the first inclined surface and the second inclined surface, and The top of the conical portion is located at a level lower than the levels of the outer peripheral surface and the wing side surfaces.

14. The secondary battery according to claim 1, wherein The opening is located at each of opposite ends of the battery can in the second direction, and Wherein, the cap assembly includes a pair of side terminals at the opposite ends of the battery can to be electrically connected to the positive electrode plate and the negative electrode plate.

15. A battery module, comprising: A plurality of battery cells, each battery cell comprising: a corresponding battery can configured to accommodate the electrode assembly and having a can width in a first direction and a can length in a second direction intersecting the first direction; and a corresponding cap assembly including an electrode terminal and welded to an end of the corresponding battery can, the plurality of battery cells being aligned along a row in a third direction so that the battery cans of the plurality of battery cells face each other; a plurality of connection terminals on top surfaces of the plurality of battery cells and connected to the electrode terminals of the plurality of battery cells through connection wires connecting the electrode terminals to each other; a plurality of connecting tabs for connecting a group of the connecting terminals to each other to transmit electric energy; and a protection circuit connected to the plurality of connection tabs to protect the plurality of battery cells from overcurrent, Wherein, each of the multiple battery cells also includes a side welding portion, the welding end of the corresponding battery can is accommodated in a welding recess at the side of the corresponding cover assembly and welded to the side welding portion, and the side welding portion has a surface located at the same level as or at a level lower than the level of the outer peripheral surface of the corresponding battery can.

16. The battery module according to claim 15, wherein: The corresponding cover assembly comprises: a body having a body front surface exposed to the outside, a body rear surface defining a receiving space as an inner space of the corresponding battery can, and a first thickness from the body front surface to the body rear surface in the second direction; and A wing has a wing front surface flush with the main body front surface, a wing rear surface defining the welding recess, and a second thickness from the wing front surface to the wing rear surface in the second direction, the second thickness being less than the first thickness.

17. The battery module according to claim 16, wherein: The width of the corresponding cap assembly is smaller than the can width of the corresponding battery can, and Wherein, the side welding portion comprises: a welding portion that joins the wing rear surface, the main body side surface, and the welding end to each other; and The weld bead portion extends from the weld portion along the wing side surface and has a maximum thickness corresponding to the thickness of the weld step portion.

18. The battery module according to claim 16, wherein: The corresponding cover assembly comprises: a main body having a main body front surface exposed to the outside, a main body rear surface defining the accommodation space, and a first thickness from the main body front surface to the main body rear surface in the second direction; and A wing having a wing front surface, a wing reduced rear surface, a wing weld bead rear surface and a wing weld bead side surface, wherein the wing front surface is flush with the main body front surface, the wing reduced rear surface defines the welding recess, the wing weld bead side surface is connected to the wing weld bead rear surface and the wing reduced rear surface and has a step portion relative to the main body side surface, the wing having a second thickness from the wing front surface to the wing reduced rear surface in the second direction and a third thickness from the wing front surface to the wing weld bead rear surface in the second direction, the second thickness is less than the first thickness, and the third thickness is less than the second thickness, wherein the corresponding cover assembly has a first side recessed portion which is communicatively connected to the welding recessed portion and is defined by the wing weld bead rear surface and the wing weld bead side surface, wherein the welding end comprises: a tank bead side surface stepped relative to the peripheral surface and located at the same level as that of the wing bead side surface; and a tank bead front surface facing the wing bead rear surface in the second direction and connected to the tank bead side surface and the peripheral surface, and The welding end has a second side recessed portion which is communicatively connected to the welding recessed portion and the first side recessed portion and is defined by the tank weld bead side surface and the tank weld bead front surface.

19. The battery module according to claim 18, wherein: The side welding portion comprises: a welding portion that joins the wing reduced rear surface, the main body side surface, and the welding end to each other; and A weld bead portion is connected to the welding portion and covers the wing bead side surface and the tank bead side surface, the weld bead portion extends in a conical shape along the wing bead rear surface and the tank bead front surface, and the tip of the weld bead portion is located at a level lower than that of the wing side surface and the outer peripheral surface.

20. The battery module according to claim 15, wherein: The respective cap assemblies include a pair of side terminals at opposite ends of the respective battery cans to be electrically connected to the positive electrode plates and the negative electrode plates.

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