Secondary battery

Abstract

Disclosed herein is a secondary battery capable of stably connecting electrode tabs to a current collector as the number of electrode assemblies increases. The secondary battery includes a case, a plurality of electrode assemblies, a plurality of electrode tab bundles respectively formed on electrodes of the plurality of electrode assemblies, a current collector coupled with the plurality of electrode tab bundles, and a cap assembly. The current collector includes a main support plate on which a connection terminal connected to an external terminal is positioned, and a plurality of branches extending from a side surface of the main support plate in a width direction of the electrode assemblies, to which the electrode tab bundles are coupled.

Description

Cross-references to related applications

[0001] This application claims priority and benefit to Korean Patent Application Nos. 10-2025-0038280 and 10-2025-0099304, filed with the Korean Intellectual Property Office on March 25, 2025 and July 22, 2025, respectively, the entire disclosure of which is incorporated herein by reference. Background Technology 1. Technical Field

[0002] This disclosure relates to a rechargeable and dischargeable secondary battery. 2. Related Technologies

[0003] Recently, with the rapid increase in demand for portable electronic products such as laptops, cameras and mobile phones, and the formalization of the development of electric vehicles, energy storage batteries, robots, satellites, etc., a great deal of research has been conducted on high-performance rechargeable and rechargeable batteries.

[0004] Currently, commercially available rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium-ion batteries. Among them, lithium-ion batteries have attracted attention because, compared to nickel-based batteries, they have little or no memory effect, allow for free charging and discharging, have a very low self-discharge rate, and offer high energy density.

[0005] This type of lithium secondary battery primarily uses lithium-based oxide and carbon materials as the positive and negative electrode active materials, respectively. Additionally, the lithium secondary battery includes: a positive electrode plate and a negative electrode plate, each coated with a positive and negative electrode active material; an electrode assembly in which the positive and negative electrode plates are disposed between the positive and negative electrode plates by a separator; and a casing configured to hermetically house the electrode assembly and the electrolyte.

[0006] Based on the shape of the battery casing, lithium secondary batteries can be divided into can-type secondary batteries and pouch-type secondary batteries. In can-type secondary batteries, the electrode assembly is embedded in a metal can, while in pouch-type secondary batteries, the electrode assembly is embedded in a pouch formed of aluminum laminate. Based on the shape of the metal can, can-type secondary batteries can also be divided into cylindrical batteries and prismatic batteries.

[0007] In the case of a prismatic battery, multiple electrode tabs connected to the electrode plate are clustered together and pre-welded, and then welded again to the current collector. As the thickness of the electrode assembly increases, the length of the electrode tabs required for pre-welding increases, and it is necessary to stably connect these electrode tabs to the current collector. Summary of the Invention

[0008] Therefore, the purpose of this disclosure is to provide a secondary battery that can increase the energy density per unit volume by reducing the space occupied by electrode contacts and the like within the casing.

[0009] Another object of this disclosure is to provide a secondary battery that can reduce the current resistance caused by the increase in electrode tab length as current is delivered to the electrode assembly through external terminals.

[0010] Another object of this disclosure is to provide a secondary battery that can stably connect electrode tabs to a current collector as the number of electrode components increases.

[0011] A secondary battery according to an embodiment of the present disclosure may include: a housing; a plurality of electrode assemblies housed within the housing, each electrode assembly having an electrode tab bundle; a current collector connected to the electrode tab bundles of the plurality of electrode assemblies; and a cover assembly sealing an opening of the housing and having an external terminal connected to the current collector, wherein the current collector may include a main support plate and a plurality of branches, the main support plate having a connection terminal for connection to the external terminal positioned thereon, the plurality of branches extending from a side of the main support plate along the width direction of the electrode assembly and spaced apart from each other in the thickness direction of the electrode assembly, each of the plurality of branches being connected to one or both electrode tab bundles of the plurality of electrode assemblies.

[0012] Electrode tab bundles can be formed by stacking the protruding, uncoated portions of the electrodes of an electrode assembly in the thickness direction and performing a first weld.

[0013] The ends of the electrode tab bundle can be fixed to the corresponding branches of the multiple branches by a second welding.

[0014] The second welded area formed at the end by the second weld can at least partially overlap with the first welded area formed at the end by the first weld.

[0015] The second welding area can be located within the first welding area.

[0016] The area of ​​the first welded region formed at the end by the first weld can be 1.1 to 5 times the area of ​​the second welded region formed at the end by the second weld.

[0017] In the width direction, the length of the first welding area can be greater than the length of the second welding area.

[0018] Multiple branches may include a first branch and a second branch spaced apart from each other in the thickness direction of the electrode assembly.

[0019] The first branch and the second branch are respectively connected to different numbers of electrode tab bundles.

[0020] The first branch connects to two electrode tab bundles, and the second branch connects to one electrode tab bundle.

[0021] Two electrode patch bundles and one electrode patch bundle can be arranged in a row along the thickness direction.

[0022] Two electrode tab bundles can be bent toward each other along the thickness direction and connected to the first branch, and one electrode tab bundle can be bent in the same direction as the adjacent electrode tab bundle of the two electrode tab bundles and connected to the second branch.

[0023] Multiple electrode assemblies may include three electrode assemblies arranged in parallel along the thickness direction, and each of the three electrode assemblies may be provided with an electrode tab bundle.

[0024] In the thickness direction, the first width of the first branch can be greater than the second width of the second branch.

[0025] The first width of the first branch and the second width of the second branch can satisfy Equation 1 below.

[0026] [Formula 1]

[0027] 1 / 3*C1 ≤ C2 ≤ 1 / 1.5*C1

[0028] Where C1 represents the first width and C2 represents the second width.

[0029] The first area of ​​the first branch and the second area of ​​the second branch can satisfy the following equation 2.

[0030] [Equation 2]

[0031] 1 / 3*S1 ≤ S2 ≤ 1 / 1.5*S1

[0032] Where S1 represents the first area and S2 represents the second area.

[0033] The thickness-direction spacing between the first branch and the second branch can satisfy Equation 3 below.

[0034] [Formula 3]

[0035] 1 / 2*C2 ≤ CD ≤ C1

[0036] Where C1 represents the first width, C2 represents the second width, and CD represents the spacing between the first branch and the second branch.

[0037] The electrode tab bundles of multiple electrode assemblies can be respectively connected to the upper surface of the first branch and the upper surface of the second branch.

[0038] Multiple electrode assemblies with the same polarity can be arranged in a row along the thickness direction.

[0039] The first branch and the second branch are each connected to the same number of electrode tab bundles.

[0040] The connection terminal can be configured to be adjacent to the side end of the electrode assembly in the width direction.

[0041] The connecting terminals can have a cylindrical shape.

[0042] The main support plate and multiple branches can be located in the same plane.

[0043] The flatness of the main support plate and multiple branches can be from 0.05 to 2.

[0044] In the width direction, the total length of the current collector can be 0.5 to 0.75 times the length of the electrode assembly.

[0045] The secondary battery also includes an insulation retainer, which supports the current collector and can be connected to the current collector.

[0046] A portion of the electrode tab bundle can be held bent toward the upper surface of the electrode assembly by an insulating tape, and the insulating tape can be disposed between the current collector and this portion of the electrode tab bundle.

[0047] The secondary battery may also include an exhaust portion formed in the housing or cover assembly, and the longitudinal axis of the exhaust portion may be parallel to or intersect the width direction.

[0048] The side of the insulation retainer may be formed with a notch or groove, so that a portion of the side surface of the current collector supported in the insulation retainer is exposed through the notch or groove.

[0049] In the direction in which the electrode tab bundle protrudes from the electrode assembly, the edge of the first welding area formed at the end by the first welding can be flush with or spaced apart from the edge of the end.

[0050] Each of the first branch and the second branch is connected to only one electrode patch bundle, and the width of the current collector in the thickness direction can be less than half the sum of the thicknesses of the corresponding electrode assemblies of the electrode patch bundles connected to the first branch and the second branch respectively.

[0051] The first branch and the second branch are each connected to two electrode tab bundles, and the spacing between the first branch and the second branch in the thickness direction can be greater than half the sum of the thicknesses of the middle adjacent electrode assemblies in the corresponding electrode assemblies of the electrode tab bundles connected to the first branch and the second branch.

[0052] The multiple branches may also include a third branch, which is connected to one or two electrode tab bundles.

[0053] The current collector is connected on the plurality of electrode assemblies such that the edge of each of the plurality of branches extending parallel to the width direction of the plurality of electrode assemblies is close to the center portion of the corresponding electrode assembly in the thickness direction.

[0054] The width of the branch connecting the multiple branches with two electrode tab bundles is less than half the sum of the thicknesses of the two electrode assemblies corresponding to the two electrode tab bundles.

[0055] The thickness-direction spacing between adjacent branches of the plurality of branches, each connected to two electrode tab bundles, is greater than the thickness-direction spacing between adjacent branches of the plurality of branches, each connected to a different number of electrode tab bundles.

[0056] Each electrode bundle includes a positive electrode bundle and a negative electrode bundle spaced apart from each other in the width direction. The current collector includes a first current collector and a second current collector spaced apart from each other in the width direction. The external terminals include a first external terminal and a second external terminal. The positive electrode bundles of the plurality of electrode assemblies are connected to multiple branches of the first current collector to connect to the first external terminal, and the negative electrode bundles of the plurality of electrode assemblies are connected to multiple branches of the second current collector to connect to the second external terminal.

[0057] The first and second current collectors are symmetrically arranged with respect to a central axis parallel to the thickness direction of the plurality of electrode assemblies. Alternatively, the first and second current collectors are symmetrically arranged with respect to the virtual center point of the surface of the plurality of electrode assemblies on which the electrode patch bundle is disposed.

[0058] The sum of the lengths of the first current collector in the width direction and the second current collector in the width direction is 0.5 to 0.75 times the length of the electrode assembly. Attached Figure Description

[0059] The above and other objects, features and advantages of this disclosure will become more clearly understood from the following detailed description taken in conjunction with the accompanying drawings:

[0060] Figure 1 This is a perspective view of a secondary battery according to a first embodiment of the present disclosure;

[0061] Figure 2 It is along Figure 1 A cross-sectional view taken from line A1-A1;

[0062] Figure 3This is a perspective view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to a first embodiment of the present disclosure;

[0063] Figure 4 It's a diagram. Figure 3 A plan view of multiple electrode assemblies;

[0064] Figure 5 This is a plan view illustrating the state in which the electrode tab bundle is connected to the current collector according to the first embodiment of the present disclosure;

[0065] Figure 6 This is a perspective view of a current collector according to a first embodiment of the present disclosure;

[0066] Figure 7 It is along Figure 3 A cross-sectional view taken from line A2-A2;

[0067] Figure 8 This is a side view of an electrode in which an electrode tab bundle is formed, according to a first embodiment of the present disclosure;

[0068] Figure 9 This is a view illustrating the state in which the electrode tab bundles of one or more electrode assemblies according to a first embodiment of the present disclosure undergo a first welding process.

[0069] Figure 10 This is a perspective view of a current collector according to a second embodiment of the present disclosure;

[0070] Figure 11 It is illustrated in the diagram. Figure 10 A cross-sectional view of the current collector connected to the electrode assembly;

[0071] Figure 12 This is a plan view illustrating the state in which the electrode tab bundle is connected to the current collector according to the third embodiment of the present disclosure;

[0072] Figure 13 This is a side view of an electrode in which an electrode pad bundle is formed, according to a third embodiment of the present disclosure.

[0073] Figure 14 This is a plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the fourth embodiment of the present disclosure;

[0074] Figure 15 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the fifth embodiment of the present disclosure;

[0075] Figure 16This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to a sixth embodiment of the present disclosure.

[0076] Figure 17 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the seventh embodiment of the present disclosure;

[0077] Figure 18 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the eighth embodiment of the present disclosure.

[0078] Figure 19 This is a perspective view of the exhaust portion according to the ninth embodiment of the present disclosure, viewed from below.

[0079] Figure 20 This is a perspective view of a secondary battery according to the tenth embodiment of the present disclosure;

[0080] Figure 21 The illustration shows the view from above. Figure 20 A plan view of a secondary battery; and

[0081] Figure 22 This is a perspective view of the exhaust portion according to the eleventh embodiment of the present disclosure, viewed from below. Detailed Implementation

[0082] Because this disclosure can be modified in various forms and has various implementations, specific implementations will be illustrated in the accompanying drawings and described in detail with reference to the drawings. However, this is not intended to limit this disclosure to a particular mode of practice, and it should be understood that all variations, equivalents, and alternatives without departing from the spirit and scope of this disclosure are included in this disclosure.

[0083] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. In this disclosure, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It will also be understood that the terms “comprising,” “including,” “having,” etc., as used in this specification, are intended to specify the presence of the stated features, integers, steps, operations, elements, components, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0084] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that throughout the drawings, the same reference numerals refer to the same elements. To avoid unnecessarily obscuring the spirit of the present disclosure, details of well-known configurations and functions may be omitted. For the same reason, some elements in the drawings are enlarged, omitted, or depicted schematically.

[0085] The secondary battery according to the first embodiment of the present disclosure will be described below.

[0086] Figure 1 This is a perspective view of a secondary battery according to a first embodiment of the present disclosure. Figure 2 It is along Figure 1 The cross-sectional view taken by line A1-A1, and Figure 3 This is a perspective view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to a first embodiment of the present disclosure.

[0087] Reference Figures 1 to 3 The secondary battery 10 according to an embodiment of the present disclosure includes: a plurality of electrode assemblies 500, each electrode assembly including a positive electrode 11 and a negative electrode 12; a housing 100 that houses the electrode assemblies 500; a cover assembly that includes a cover plate 21 and external terminals, the cover plate 21 being connected to the housing 100 and the external terminals being mounted on the cover plate 21; an upper insulator 29 disposed between the cover plate 21 and the electrode assemblies 500; and an exhaust portion 50 disposed on the cover plate 21.

[0088] Each electrode assembly in the electrode assembly 500 can perform charging and discharging, and can be implemented in various forms such as all-solid-state electrode assembly, lithium-ion electrode assembly or sodium-ion electrode assembly.

[0089] Each electrode assembly in the electrode assembly 500 may include a positive electrode 11, a negative electrode 12, and a separator 13 disposed between the positive electrode 11 and the negative electrode 12, and the positive electrode 11, the separator 13 and the negative electrode 12 may be constructed in a stacked structure or in a wound structure.

[0090] Furthermore, the electrode assembly 500 may have a structure in which the positive electrode 11 and the negative electrode 12 are alternately inserted between portions of the spacer 13 folded in a serrated shape. Additionally, the electrode assembly 500 may be implemented in various forms, such as an all-solid-state type excluding the spacer.

[0091] The positive electrode 11 and negative electrode 12, serving as electrodes, may each include a coated portion and an uncoated portion. The coated portion is the area on which active material is applied to the metal foil, and the uncoated portion is the area on which no active material is applied. The uncoated portion of the positive electrode protrudes from the side end of the positive electrode 11, and the uncoated portion of the negative electrode protrudes from the side end of the negative electrode 12. Both the uncoated portions of the positive and negative electrodes may protrude in the same direction toward the cover plate 21, that is, in the longitudinal direction of the electrode assembly 500 corresponding to the z-axis direction.

[0092] The uncoated positive and negative electrode portions can be formed into tab shapes and can be spaced apart from each other in the width direction corresponding to the y-axis of the electrode assembly 500. The uncoated positive and negative electrode portions can be stacked in the thickness direction corresponding to the x-axis of the electrode assembly 500. In this case, the stacked uncoated positive electrode portions can form a first electrode tab bundle 11a, 11b, 11c (positive electrode tab bundle), and the stacked uncoated negative electrode portions can form a second electrode tab bundle 12a, 12b, 12c (negative electrode tab bundle).

[0093] Furthermore, the first electrode patch bundles 11a, 11b, and 11c can be electrically connected to the first external terminal 23 via the first current collector 310, and the second electrode patch bundles 12a, 12b, and 12c can be electrically connected to the second external terminal 24 via the second current collector 330. A detailed description of the connection structure between the first electrode patch bundles 11a, 11b, and 11c and the first current collector 310, and the connection structure between the second electrode patch bundles 12a, 12b, and 12c and the second current collector 330, according to this embodiment, will be provided later.

[0094] The separator 13 is disposed between the positive electrode 11 and the negative electrode 12, and the separator 13 prevents short circuits and allows ions to move. When the secondary battery 10 is implemented as an all-solid-state battery, instead of the separator 13, the solid electrolyte can be positioned between the positive electrode 11 and the negative electrode 12.

[0095] The housing 100 can be formed in the shape of a box having an internal space for accommodating the electrode assembly 500. The housing 100 can be made in various shapes, such as prism or cylinder. Multiple electrode assemblies 500 can be inserted into the housing 100.

[0096] The electrolyte can be housed together with the electrode assembly 500 inside the housing 100. The electrolyte can be in a liquid, solid, or gel state.

[0097] The cover plate 21 can be formed as a plate member that covers the opening of the housing 100, and can have a shape corresponding to the shape of the opening of the housing 100. The cover plate 21 can be fixed to the housing 100 by welding.

[0098] An electrolyte injection port H1 for injecting electrolytes and an exhaust port H2 in which an exhaust portion 50 is installed can be formed in the cover plate 21. A sealing plug 28 for closing the electrolyte injection port H1 can be installed in the electrolyte injection port H1, and an exhaust portion 50 that opens under a preset pressure can be formed in the exhaust port H2.

[0099] In this embodiment, the exhaust portion 50 may extend relatively long in the width direction corresponding to the y-axis direction. The exhaust portion 50 may have a shape that extends in the width direction (y-axis direction), such as a rectangular shape, an elliptical shape, or a rounded rectangular shape.

[0100] In addition, the exhaust portion 50 can be fixed to the cover plate 21 by welding. The exhaust portion 50 can be fixed to the lower surface of the cover plate 21, or it can be fixed to the upper surface of the cover plate 21.

[0101] The exhaust portion 50 may include two side recesses 52 and 53 and a connecting recess 51 connecting the side recesses 52 and 53. The connecting recess 51 and the side recesses 52 and 53 may be formed as elongated grooves and may be grooves with a trapezoidal cross-sectional shape. However, this disclosure is not limited thereto, and the connecting recess 51 and the side recesses 52 and 53 may have various cross-sectional shapes, such as triangular or arcuate shapes.

[0102] The connecting notch 51 can be formed as a curved line to create a wavy or S-shaped shape. The two side notches 52 and 53 can be formed as an arc shape and can convexly protrude outwards in the width direction (y-axis direction) towards the exhaust portion 50 while protruding in opposite directions. The side notches 52 and 53 can be connected to the connecting notch 51, and the side notches 52 and 53 can have the same structure and be arranged in a linearly symmetrical manner.

[0103] In this embodiment, the exhaust portion 50 is formed to extend relatively long along the width direction (y-axis direction). Since the distance between the first current collector 310 and the second current collector 330 is large enough, the gas can be discharged smoothly without being disturbed by the first current collector 310 and the second current collector 330, even when the exhaust portion 50 is arranged along the width direction (y-axis direction).

[0104] The upper insulator 29 can be disposed below the cover plate 21, and the upper insulator 29 can be formed as a plate parallel to the cover plate 21, and can extend in the width direction (y-axis direction) of the electrode assembly 500.

[0105] External terminals can be connected to cover plate 21, and one or two external terminals can be mounted on cover plate 21. When two external terminals are mounted on cover plate 21, the first external terminal 23 can be configured as the positive terminal, and the second external terminal 24 can be configured as the negative terminal. When a single external terminal is mounted on cover plate 21, housing 100 can be charged as the negative terminal.

[0106] The first external terminal 23 and the second external terminal 24 can be formed in a plate shape. An insulating washer 25 can be provided between the first external terminal 23 and the cover plate 21, and an insulating washer 26 can also be provided between the second external terminal 24 and the cover plate 21. Furthermore, the washers 25 and 26 can extend downwards and be positioned between the first current collector 310 and the second current collector 330 and the cover plate 21. Each of the washers 25 and 26 can be formed as a single component or can be divided into multiple parts.

[0107] The first external terminal 23 and the second external terminal 24 can be formed in the shape of a plate, and a hole for inserting the first connecting terminal 317 or the second connecting terminal 337 of the first current collector 310 or the second current collector 330 can be formed at the center portion of the first external terminal 23 or the second external terminal 24.

[0108] In this embodiment, electrode assembly 500 may include three electrode assemblies. Each of electrode assemblies 510, 530, and 550 may be an electrode assembly having the same internal structure.

[0109] Multiple electrode assemblies 510, 530, and 550 may be stacked along the thickness direction (x-axis direction) of electrode assembly 500. Each of the multiple electrode assemblies 510, 530, and 550 may include a first electrode tab bundle 11a, 11b, and 11c corresponding to a positive electrode and a second electrode tab bundle 12a, 12b, and 12c corresponding to a negative electrode. Each of the electrode assemblies 510, 530, and 550 may be provided with the same number of first electrode tab bundles 11a, 11b, and 11c and the same number of second electrode tab bundles 12a, 12b, and 12c. That is, in each of the first electrode assembly 510, the second electrode assembly 530, and the third electrode assembly 550, the first electrode tab bundles 11a, 11b, and 11c may include the same number of stacked tabs. Furthermore, in each of the first electrode assembly 510, the second electrode assembly 530, and the third electrode assembly 550, the second electrode patch bundles 12a, 12b, and 12c may include the same number of stacked patches.

[0110] At this time, multiple first electrode patch bundles 11a, 11b, and 11c can be arranged in a row along the thickness direction (x-axis direction), and multiple second electrode patch bundles 12a, 12b, and 12c can also be arranged in a row along the thickness direction (x-axis direction). The multiple first electrode patch bundles 11a, 11b, and 11c can be positioned at one end along the width direction (y-axis direction) of the electrode assembly 500, while the multiple second electrode patch bundles 12a, 12b, and 12c can be positioned at the other end along the width direction (y-axis direction) of the electrode assembly 500.

[0111] Figure 4 It's a diagram. Figure 3 A plan view of multiple electrode assemblies. Figure 5 This is a plan view illustrating the state in which the electrode patch bundle is connected to the current collector according to the first embodiment of the present disclosure. Figure 6 This is a perspective view of a current collector according to a first embodiment of the present disclosure. Figure 7 It is along Figure 3 A cross-sectional view taken from line A2-A2. Figure 8 The illustration shows a side view of an electrode in which an electrode patch bundle is formed, according to a first embodiment of the present disclosure. Figure 9 This is a view illustrating the state in which the electrode tab bundles of one or more electrode assemblies according to a first embodiment of the present disclosure undergo a first welding process.

[0112] Reference Figures 4 to 9 In this embodiment, the first electrode assembly 510, the second electrode assembly 530 and the third electrode assembly 550 are stacked along the thickness direction (x-axis direction). The first electrode tab bundles 11a, 11b and 11c of the positive electrode can be connected to the first current collector 310, and the second electrode tab bundles 12a, 12b and 12c of the negative electrode can be connected to the second current collector 330.

[0113] In this embodiment, the first current collector 310 may include a main support plate 311 and multiple branches 313 and 315. The main support plate 311 may be a flat plate-shaped member supporting the first connecting terminal 317. The first connecting terminal 317 may be positioned on the upper surface of the main support plate 311, and the first connecting terminal 317 may be electrically connected to a first external terminal 23 connected to the cover plate 21. In this case, the first connecting terminal 317 may have a cylindrical shape.

[0114] Multiple branches 313 and 315 may be formed on the side of the main support plate 311. Each of the multiple branches 313 and 315 may extend along the width direction (y-axis direction). The multiple branches 313 and 315 may also be flat plate-like members, similar to the main support plate 311. In this embodiment, the main support plate 311 and the multiple branches 313 and 315 of the first current collector 310 may be formed as a single flat plate-like member, i.e., they may be located in the same plane.

[0115] The first branch 313 and the second branch 315 can have a rectangular shape that extends in the width direction (y-axis direction). Therefore, the first current collector 310 according to this embodiment can have an approximately U-shaped configuration.

[0116] The multiple branches 313 and 315 may include a first branch 313 and a second branch 315 respectively formed extending from the side surface of the main support plate 311. The first branch 313 and the second branch 315 may be spaced apart from each other along the thickness direction (x-axis direction). In this case, the first branch 313 and the second branch 315 may be spaced apart by a spacing distance CD.

[0117] In this embodiment, the width of the first branch 313 and the width of the second branch 315 may be different from each other. The first branch 313 may have a first width C1, and the second branch 315 may have a second width C2. Here, the first width C1 and the second width C2 represent the widths of the first branch 313 and the second branch 315 in the thickness direction (x-axis direction), respectively.

[0118] Specifically, the first width C1 of the first branch 313 can be greater than the second width C2 of the second branch 315. Thus, two electrode tab bundles, namely the first electrode tab bundle 11a and the first electrode tab bundle 11b, can be connected to the upper surface of the first branch 313, and one electrode tab bundle, namely the first electrode tab bundle 11c, can be connected to the upper surface of the second branch 315. In other words, different numbers of electrode tab bundles can be connected to the first branch 313 and the second branch 315.

[0119] On the upper surface of the first branch 313, the first electrode tab bundle 11a and the first electrode tab bundle 11b can be bent along the thickness direction (x-axis direction) to face each other and be connected to the upper surface of the first branch 313. The first electrode tab bundle 11a and the first electrode tab bundle 11b can be bent in opposite directions along the thickness direction (x-axis direction) and welded to the upper surface of the first branch 313.

[0120] On the upper surface of the second branch 315, an electrode tab bundle, namely the first electrode tab bundle 11c, can be bent and connected to the upper surface of the second branch 315 in the same direction as the adjacent first electrode tab bundle 11b.

[0121] Therefore, the first electrode tab bundle 11b and the first electrode tab bundle 11c can be bent in the same direction, and the first electrode tab bundle 11a can be bent in a different direction from the first electrode tab bundle 11b and the first electrode tab bundle 11c and connected to the branch.

[0122] In this case, the first width C1 of the first branch 313 and the second width C2 of the second branch 315 can satisfy the following [Equation 1].

[0123] [Formula 1] 1 / 3*C1 ≤ C2 ≤ 1 / 1.5*C1

[0124] In other words, the first width C1 of the first branch 313 can be approximately 1.5 to 3 times the second width C2 of the second branch 315. When the first width C1 of the first branch 313 is less than 1.5 times the second width C2 of the second branch 315, portions of the first electrode tab bundles 11a and 11b connected to the upper surface of the first branch 313 may overlap. Therefore, the resistance caused by the first electrode tab bundles 11a and 11b connected to the upper surface of the first branch 313 may increase, and the connection strength with the first current collector 310 may weaken due to the overlap of the first electrode tab bundles 11a and 11b. On the other hand, when the first width C1 of the first branch 313 is more than 3 times the second width C2 of the second branch 315, the area of ​​the first current collector 310 may increase, which may increase the resistance to the current flowing through the first current collector 310.

[0125] Preferably, the first current collector 310 can be designed such that the first electrode tab bundles 11a, 11b, and 11c can all protrude from the center portion of the respective electrode assembly in the thickness direction and connect to the corresponding branch of the first current collector 310. Figure 3-9 In the example shown, the first electrode tab bundles 11a and 11b are connected to the first branch 313. The first width C1 of the first branch 313 is less than half the sum of the thicknesses of the first electrode assembly 510 and the second electrode assembly 530, such that the first electrode tab bundles 11a and 11b can both protrude upwards from the center portion of the first electrode assembly 510 and the second electrode assembly 530 in the thickness direction and connect to the first branch 313. When the first electrode assembly 510, the second electrode assembly 530, and the third electrode assembly 550 all have the same dimensions (thickness, width, height), the first width C1 of the first branch 313 is less than the thickness of one electrode assembly. In the example shown, only the first electrode tab bundle 11c is connected to the second branch 315. The second width C2 of the second branch 315 is less than half the sum of the thicknesses of the second electrode assembly 530 and the third electrode assembly 550, and can be designed to be as small as possible, as long as it ensures that the first electrode tab bundle 11c can be stably connected to the second branch 315.

[0126] Meanwhile, the first area S1 of the first branch 313 and the second area S2 of the second branch 315 can satisfy the following [Equation 2].

[0127] [Equation 2] 1 / 3*S1 ≤ S2 ≤ 1 / 1.5*S1

[0128] In other words, the first area S1 of the first branch 313 can be approximately 1.5 to 3 times the second area S2 of the second branch 315. When the first area S1 of the first branch 313 is less than 1.5 times the second area S2 of the second branch 315, portions of the first electrode tab bundle 11a and the first electrode tab bundle 11b connected to the upper surface of the first branch 313 may overlap each other. On the other hand, when the first area S1 of the first branch 313 is more than 3 times the second area S2 of the second branch 315, the total area of ​​the first current collector 310 may increase, thereby potentially increasing the resistance to the current flowing through the first current collector 310.

[0129] Meanwhile, the first width C1 of the first branch 313, the second width C2 of the second branch 315, and the interval distance CD can satisfy the following [Equation 3].

[0130] [Formula 3] 1 / 2*C2 ≤ CD ≤ C1

[0131] In other words, the spacing distance CD can be less than or equal to the first width C1 of the first branch 313, and greater than or equal to half of the second width C2 of the second branch 315. When the spacing distance CD deviates from the above range, the electrode tab bundle connected to the upper surface of the branch may not be connected to the upper surface of the branch and may not protrude upward from the center portion of the corresponding electrode assembly. Instead, the electrode tab bundle may protrude upward from a position adjacent to the side surface of the electrode assembly, thereby deviating from the center portion of the electrode assembly, in order to connect to the upper surface of the branch. In this case, compared to the case where the electrode tab bundle is located at the center portion, the length of the electrode tab bundle protruding from the corresponding electrode assembly increases, thereby increasing manufacturing costs.

[0132] Furthermore, the length CC of the first branch 313 and the second branch 315 in the width direction (y-axis direction) can be 0.6 to 0.9 times the total length CB of the first current collector 310. That is, the length CC of the first branch 313 and the second branch 315 can occupy approximately half or more of the total length CB of the first current collector 310. In this case, the length IT1 of the first electrode patch bundles 11a, 11b, and 11c connected to the upper surfaces of the first branch 313 and the second branch 315 can be 0.7 to 0.95 times the length CC of the first branch 313 and the second branch 315. Similarly, the length IT1 of the first electrode patch bundles 11a, 11b, and 11c can occupy approximately half or more of the length CC of the first branch 313 and the second branch 315.

[0133] Meanwhile, the total length of the current collector 300, i.e., the sum of the length CB of the first current collector 310 in the width direction (y-axis direction) and the length CB of the second current collector 330 in the width direction (y-axis direction), can be 0.5 to 0.75 times the length L1 of the electrode assembly 500. When the electrode assembly 500 is viewed from above, the above range can represent the proportion of the length of the electrode assembly 500 in the width direction (y-axis direction) occupied by the entire current collector 300. When the total length of the current collector 300 exceeds the above range, the space occupied by the current collector 300 in the width direction (y-axis direction) increases, thereby imposing greater restrictions on the arrangement of the exhaust section 50. The exhaust section 50 is arranged in an empty space in the vertical direction where no electrode contacts, current collectors, etc. are positioned, i.e., in a position where it does not overlap with electrode contacts, current collectors, etc. in the vertical direction. When the above range is exceeded, this empty space will decrease, and therefore may restrict the placement of the exhaust section 50.

[0134] Therefore, as in this embodiment, when the proportion of the entire current collector 300 meets the above range, the position of the exhaust portion 50 can be freely selected, and the direction of the exhaust portion 50 can be freely determined. Here, the direction of the exhaust portion 50 refers to the direction in which the longitudinal side of the exhaust portion 50 extends, and the exhaust portion 50 can be arranged along the width direction (y-axis direction), i.e., horizontally, or along the thickness direction (x-axis direction), i.e., vertically.

[0135] In this embodiment, the entire first current collector 310 can be formed as a single flat plate-like component, and the flatness of the first current collector 310 can be in the range of 0.05 to 2. Flatness indicates the degree to which the first current collector 310 is planar, and a smaller value indicates a flatter configuration. The flatness of the first current collector 310 refers to the flatness of the current collector surface of the main support plate 311 and the plurality of branches 313, 315 (e.g., at least including the current collector surface of the portion formed by the main support plate 311, branches 313, branches 315 (excluding the first connecting terminal 317) and optionally the opposite surface of that portion), which can be a geometric tolerance (e.g., a geometric tolerance based on geometric dimensions and tolerances (GD&T)) that indicates that all points on the surfaces of the main support plate 311 and branches 313, 315 are located between two parallel planes, the gap between which corresponds to a specific flatness in millimeters. For example, if the flatness of the first current collector 310 is 0.1, it means that all points on the surfaces of the main support plate 311 and the branches 313, 315 are located within the spaced area defined by two parallel planes with a gap of 0.1 mm; or in other words, the surface can be located within a narrow gap of 0.1 mm between two perfectly flat parallel plates, and no point on the surface will contact these parallel plates. For example, the specific flatness of the first current collector 310 can be measured by placing the first current collector 310 on a flat plate (e.g., a precision-machined plate) and measuring the flatness using a feeler gauge. Alternatively, one or more of the following methods can be used to measure the specific flatness of the first current collector 310: dial indicator method, coordinate measuring machine, optical interferometry, and / or laser scanning method. When the flatness of the first current collector 310 exceeds 2, a portion of the first current collector 310 may contact the upper surface of the electrode assembly 500 located below, potentially causing a short circuit, etc. Therefore, when the flatness of the first current collector 310 falls within the corresponding range, even if the first electrode tab bundles 11a, 11b and 11c are connected to the upper surface of the first current collector 310, a short circuit with the electrode assembly 500 can be prevented.

[0136] The first current collector 310 is connected to the electrode assembly 500 such that the edge of each of the plurality of branches of the first current collector 310, which extends parallel to the width direction (y-axis direction) of the electrode assembly 500, is close to the center portion of the corresponding electrode assembly in the thickness direction (x-axis direction). For example... Figure 4As shown, the upper edge of the first branch 313, extending parallel to the width direction, is close to the center portion of the first electrode assembly 510 in the thickness direction, and the lower edge of the first branch 313, extending parallel to the width direction, is close to the center portion of the second electrode assembly 530 in the thickness direction. Furthermore, the lower edge of the second branch 315, extending parallel to the width direction, is close to the center portion of the third electrode assembly 550 in the thickness direction. With this arrangement, the electrode tab bundles protruding upwards from the center portions of the thickness direction of each electrode assembly can be easily connected to the corresponding branches of the first current collector 310, thus shortening the length of the electrode tab bundles.

[0137] Meanwhile, the second current collector 330 may have the same shape as the first current collector 310. In this embodiment, the first current collector 310 and the second current collector 330 may be symmetrically arranged on the electrode assembly 500 with respect to a central axis parallel to the thickness direction (x-axis direction).

[0138] The second current collector 330 may include a main support plate 331 and multiple branches 333 and 335. The main support plate 331 may be a flat plate-like member that supports the second connecting terminal 337. The second connecting terminal 337 may be positioned on the upper surface of the main support plate 331 and may be electrically connected to a second external terminal 24 connected to the cover plate 21. In this case, the second connecting terminal 337 may have a cylindrical shape.

[0139] The first branch 333 and the second branch 335 can be formed to extend from the side of the flat main support plate 331 along the width direction (y-axis direction). The first branch 333 and the second branch 335 can be spaced apart from each other along the thickness direction (x-axis direction).

[0140] Similar to the first current collector 310, the widths of the first branch 333 and the second branch 335 of the second current collector 330 can be different from each other. Specifically, the width of the first branch 333 can be greater than the width of the second branch 335. Thus, two negative electrode contact bundles, namely the second negative electrode contact bundle 12a and the second negative electrode contact bundle 12b, can be connected to the upper surface of the first branch 333 of the second current collector 330. Additionally, one negative electrode contact bundle, namely the second negative electrode contact bundle 12c, can be connected to the upper surface of the second branch 335 of the second current collector 330.

[0141] In this embodiment, the width of the first branch 333, the width of the second branch 335, and the spacing between the first branch 333 and the second branch 355 of the second current collector 330 can be the same as those in the first current collector 310.

[0142] like Figure 4As shown, branches 313 and 315 of the first current collector 310 and branches 333 and 335 of the second current collector 330 can extend along the width direction (y-axis direction) toward the center of the electrode assembly 500. That is, the ends of branches 313 and 315 of the first current collector 310 and the ends of branches 333 and 335 of the second current collector 330 can be configured to face each other.

[0143] The first connection terminal 317 of the first current collector 310 and the second connection terminal 337 of the second current collector 330 can be arranged adjacent to the opposite end of the electrode assembly 500 in the width direction (y-axis direction). The first connection terminal 317 can be arranged adjacent to the left end of the electrode assembly 500, and the second connection terminal 337 can be arranged adjacent to the right end of the battery assembly 500.

[0144] Reference Figure 8 and Figure 9 The first electrode tab bundle 11a of the first electrode assembly 510 is formed by tightly fixing the ends of the uncoated portions of the positive electrode protruding upward from the first electrode assembly 510 to each other by means of a first weld. Before being attached to the upper surface of the first current collector 310, the uncoated portions of the positive electrode are gathered toward the center of the first electrode assembly 510 in the thickness direction (x-axis direction) using a tab guide (not shown), and the ends of the gathered uncoated portions of the positive electrode are fixed by the first weld. By means of the first weld, a first weld area PW1 can be formed at the end of the first electrode tab bundle 11a of the positive electrode. In the direction in which the first electrode tab bundle protrudes from the electrode assembly (positive z-axis direction), the edge of the first weld area PW1 is flush with the edge of the end of the first electrode tab bundle.

[0145] In this case, the first weld can be formed to extend relatively long along the width direction (y-axis direction). The first weld can have various shapes, such as linear, spiral, or dot shapes.

[0146] The first weld is performed to prevent the ends of the first electrode tab bundle 11a from separating from each other when the first electrode tab bundle 11a is bent and fixed to the first current collector 310. The first weld can correspond to a pre-weld in which only the ends of the first electrode tab bundle 11a are fixed to each other. In this case, ultrasonic welding, laser welding, etc., can be used as the first weld. Preferably, ultrasonic welding can be used as the first weld.

[0147] Similarly, the first electrode tab bundle 11b of the second electrode assembly 530 and the first electrode tab bundle 11c of the third electrode assembly 550 can also be formed by connecting the ends of the uncoated portions of the positive electrode in the same manner to form a bundle. Furthermore, the same first welding region PW1 can be formed at the ends of the first electrode tab bundles 11b and 11c of the positive electrode by a first weld.

[0148] Alternatively, the second electrode tab bundles 12a, 12b, and 12c of the electrode assembly 500 can also be formed by tightly fixing the ends of the uncoated portions of the negative electrode to each other using a first weld. The second electrode tab bundles 12a, 12b, and 12c can be formed in the same manner as the first electrode tab bundles 11a, 11b, and 11c. In this case, a first weld area PW2 can be formed at the ends of the second electrode tab bundles 12a, 12b, and 12c of the negative electrode by the first weld.

[0149] Refer again Figures 4 to 7 The first electrode tab bundles 11a, 11b, and 11c of the electrode assembly 500 can be arranged in a row along the thickness direction (x-axis direction). That is, when viewed along the thickness direction (x-axis direction), the first electrode tab bundles 11a, 11b, and 11c can be arranged to overlap each other. The first electrode tab bundles 11a, 11b, and 11c can all protrude from the side ends at the same location on the positive electrode 11. In this embodiment, since the second electrode tab bundles 12a, 12b, and 12c of the electrode assembly 500 have the same structure as the first electrode tab bundles 11a, 11b, and 11c, their detailed description will be omitted.

[0150] Thus, the ends of the first electrode tab bundles 11a, 11b, and 11c can be arranged in a row along the thickness direction (x-axis direction) and connected to the upper surface of the first current collector 310. The ends of the first electrode tab bundles 11a, 11b, and 11c can be bent and connected to the upper surface of the first current collector 310, and the first welding area PW1 formed at the ends of the first electrode tab bundles 11a, 11b, and 11c can be positioned on the upper surface of the first current collector 310.

[0151] The upper ends of the first electrode tab bundle 11a and the upper ends of the first electrode tab bundle 11b can face each other and be positioned on the upper surface of the first branch 313 of the first current collector 310. Simultaneously, the upper end of the first electrode tab bundle 11c can be positioned on the upper surface of the second branch 315 of the first current collector 310. Thus, the first welding areas PW1 of the first electrode tab bundles 11a, 11b, and 11c can be arranged in a row along the thickness direction (x-axis direction) and positioned on the first current collector 310.

[0152] exist Figure 5 In this configuration, the first electrode tab bundle 11a can be bent downwards from the top and connected to the upper surface of the first branch 313, while the first electrode tab bundle 11b can be bent upwards from the bottom and connected to the first branch 313. That is, the first electrode tab bundle 11a and the first electrode tab bundle 11b can be bent and connected to the upper surface of the first branch 313 in a direction facing each other.

[0153] Meanwhile, the first electrode tab bundle 11c can be bent upward from the lower side of the electrode assembly 500 and connected to the upper surface of the second branch 315. Alternatively, the first electrode tab bundle 11c can be bent downward from the upper side of the electrode assembly 500 and connected to the upper surface of the second branch 315.

[0154] Therefore, in this embodiment, the first electrode tab bundle 11b and the first electrode tab bundle 11c can be bent upward from the lower side of the electrode assembly 500, while the first electrode tab bundle 11a can be bent downward from the upper side of the electrode assembly 500 in a direction opposite to that of the first electrode tab bundle 11b and the first electrode tab bundle 11c.

[0155] In this embodiment, the end of the first electrode tab bundle 11a can be connected to the first branch 313 by a second welding. Specifically, after the end of the first electrode tab bundle 11a is bent and comes into close contact with the upper surface of the first branch 313, the end of the first electrode tab bundle 11a is second welded so that the end of the first electrode tab bundle 11a can be connected to the first branch 313.

[0156] The second weld can be performed on the upper portion of the first weld area PW1 of the first electrode tab bundle 11a, such that the end of the first electrode tab bundle 11a is connected to the upper surface of the first current collector 310. The second weld can be formed to extend a considerable distance along the extension direction of the first branch 313, i.e., along the width direction (y-axis direction). In this case, the second weld can have various shapes, such as linear, spiral, or dot shapes.

[0157] The second weld is used to fix the end of the first electrode tab bundle 11a to the upper surface of the first current collector 310. The second weld can correspond to the main weld that fixes the first electrode tab bundle 11a to the first current collector 310. In this case, laser welding, ultrasonic welding, etc., can be used as the second weld. Preferably, laser welding can be used as the second weld.

[0158] Specifically, in this embodiment, the second welding region MW1 formed at the end of the first electrode tab bundle 11a by the second welding can at least partially overlap with the first welding region PW1 formed at the end of the first electrode tab bundle 11a. Preferably, the entire second welding region MW1 can overlap with the first welding region PW1. That is, the entire second welding region MW1 can be located within the first welding region PW1.

[0159] like Figure 5 As shown, the area of ​​the first welding region PW1 can be larger than the area of ​​the second welding region MW1. In other words, the welding region formed by the first welding can have a larger area than the welding region formed by the second welding.

[0160] In this embodiment, the area of ​​the first welding region PW1 can be 1.1 to 5 times the area of ​​the second welding region MW1. Since the ends of the first electrode tab bundle 11a are connected to each other by the first welding before the second welding is performed, the ends of the first electrode tab bundle 11a can be firmly connected to the upper surface of the first current collector 310 even when the area of ​​the second welding region MW1 is smaller than the area of ​​the first welding region PW1. That is, since the ends of the first electrode tab bundle 11a are firmly fixed in advance by the first welding, even if only a portion of the ends of the first electrode tab bundle 11a are fixed to the first current collector 310 by the second welding, the ends of the first electrode tab bundle 11a can be firmly fixed to the upper surface of the first current collector 310.

[0161] Simultaneously, the length IT1 of the first welding region PW1 in the width direction (y-axis direction) can be greater than the length M1 of the second welding region MW1. Furthermore, the thickness W1 of the first welding region PW1 in the thickness direction (x-axis direction) can be greater than the thickness W2 of the second welding region MW1. Therefore, as described above, the area of ​​the first welding region PW1 can be formed to be larger than the area of ​​the second welding region MW1.

[0162] Reference Figure 7 The ends of the first electrode tab bundles 11a, 11b, and 11c are bent and fixed to the upper surface of the first current collector 310, and the portions of the first electrode tab bundles 11a, 11b, and 11c other than the ends can be held in a bent state toward the upper surface of the electrode assembly 500 by insulating tapes T1, T2, and T3. In this case, the insulating tapes T1, T2, and T3 can be positioned between the current collector 300 and the first electrode tab bundles 11a, 11b, and 11c of the electrode assembly 500.

[0163] The portion of the first electrode tab bundle 11a adjacent to the upper surface of the first electrode assembly 510 can be bent toward the upper surface of the first electrode assembly 510 and is fixed by insulating tape T1. The portion of the first electrode tab bundle 11b adjacent to the upper surface of the second electrode assembly 530 can be bent toward the upper surface of the second electrode assembly 530 and is fixed by insulating tape T2. The portion of the first electrode tab bundle 11c adjacent to the upper surface of the third electrode assembly 550 can be bent toward the upper surface of the third electrode assembly 550 and is fixed by insulating tape T3.

[0164] The secondary battery according to the second embodiment of the present disclosure will be described below.

[0165] Figure 10 This illustration shows a perspective view of a current collector according to a second embodiment of the present disclosure, and Figure 11 It is illustrated in the diagram. Figure 10 A cross-sectional view of the current collector connected to the electrode assembly.

[0166] Reference Figure 10 and Figure 11 Since the secondary battery according to the second embodiment has the same structure as the secondary battery according to the first embodiment, except for the insulation retainer CH, redundant descriptions of the same components will be omitted.

[0167] In this embodiment, the insulation retainer CH can be disposed on the lower surface of the first current collector 310. The insulation retainer CH can support the first current collector 310 and be fixed to the lower surface of the first current collector 310. In this embodiment, the insulation retainer CH connected to the lower surface of the second current collector 330 has the same structure as the insulation retainer CH of the first current collector 310, and therefore its detailed description will be omitted.

[0168] The insulation retainer CH can prevent the first current collector 310 from being deformed or damaged during the welding process between the first electrode tab bundles 11a, 11b and 11c and the first current collector 310 or when the first current collector 310 is positioned inside the housing 100.

[0169] When the first branch 313 and the second branch 315 of the first current collector 310 deform upwards or downwards, the first branch 313 and the second branch 315 may come into contact with the upper surface of the electrode assembly 500, thereby causing damage or short circuit to the electrode assembly 500. Additionally, when the first branch 313 and the second branch 315 deform laterally, the distance between the first branch 313 and the second branch 315 may change, causing damage or breakage to the side portions of the first electrode tab bundles 11a, 11b, and 11c connected to the upper surfaces of the first branch 313 and the second branch 315. Therefore, in this embodiment, the insulation retainer CH can support and fix the first current collector 310, thereby preventing damage or short circuit to the electrode assembly 500 or the first electrode tab bundles 11a, 11b, and 11c.

[0170] The insulating retainer CH can have a shape corresponding to the shape of the first current collector 310. In this case, the insulating retainer CH can accommodate the first current collector 310. The insulating retainer CH can support the first current collector 310 while surrounding the lower and side surfaces of the accommodated first current collector 310. To prevent the accommodated first current collector 310 from disengaging, a plurality of hook-shaped portions CH_H can be provided on the side surface of the insulating retainer CH. The first current collector 310 can be fixed in the insulating retainer CH by the plurality of hook-shaped portions CH-H.

[0171] To allow the first electrode tab bundles 11a, 11b, and 11c to bend and contact the upper surface of the first current collector 310, a notched groove CH_G can be formed on the side surface of the insulating retainer CH, in which a portion of the side surface is cut off. When the first electrode tab bundles 11a, 11b, and 11c protruding from the electrode assembly 500 bend and the bent first electrode tab bundles 11a, 11b, and 11c contact the upper surface of the first current collector 310, the notched groove CH_G can prevent the first electrode tab bundles 11a, 11b, and 11c from being interfered with by the side surface of the insulating retainer CH.

[0172] Due to the notch groove CH_G, a portion of the side surface of the first current collector 310 housed in the insulation retainer CH can be exposed. Additionally, due to the notch groove CH_G, the contact area between the first current collector 310 and the first electrode tab bundles 11a, 11b, and 11c may be increased.

[0173] The secondary battery according to the third embodiment of the present disclosure will be described below.

[0174] Figure 12 This is a plan view illustrating the state in which the electrode patch bundle is connected to the current collector according to the third embodiment of this disclosure, and Figure 13This is a side view of an electrode in which an electrode pad bundle is formed, according to a third embodiment of the present disclosure.

[0175] Reference Figure 12 and Figure 13 Since the secondary battery according to the third embodiment has the same structure as the secondary battery according to the first embodiment except for the first electrode tab bundles 11a, 11b and 11c, redundant descriptions of the same components will be omitted.

[0176] In this embodiment, the first welding region PW1 may be formed at a position spaced apart from the upper end of each of the first electrode tab bundles 11a, 11b, and 11c. In the first embodiment described above, the first welding region PW1 is formed at the upper end of each of the first electrode tab bundles 11a, 11b, and 11c, such that only the first welding region PW1 is located at the side end of each of the first electrode tab bundles 11a, 11b, and 11c.

[0177] In this embodiment, the first welding region PW1 is positioned at a location spaced apart from the upper end of each first electrode tab bundle 11a, 11b, or 11c, and only the uncoated portions that are not welded are located at the side ends. That is, only the uncoated portions that are not welded are positioned between the upper end of each first electrode tab bundle 11a, 11b, or 11c and the first welding region PW1. In the direction in which the first electrode tab bundles protrude from the electrode assembly (the positive direction of the z-axis), the edge of the first welding region PW1 is spaced apart from the edge of the end of the first electrode tab bundle.

[0178] like Figure 12 As shown, not only the first welding area PW1, but also the uncoated portions of the first electrode tab bundle 11a and the first electrode tab bundle 11b can be positioned on the upper surface of the first branch 313 of the first current collector 310. Furthermore, on the upper surface of the first branch 313, the uncoated portions of the first electrode tab bundles 11a and 11b can be arranged side-by-side. The uncoated portions of the first electrode tab bundle 11c and the first welding area PW1 can be positioned on the upper surface of the second branch 315.

[0179] As the thickness of the electrode assembly 500 increases, the length of the uncoated portion increases to form the first electrode tab bundles 11a, 11b, and 11c. In order to maintain a constant distance between the upper surface of the electrode assembly 500 and the current collector 300, as the length of the uncoated portion increases, the first welding region PW1 may be spaced apart from the upper end of the first electrode tab bundles 11a, 11b, or 11c.

[0180] The secondary battery according to the fourth embodiment of the present disclosure will be described below.

[0181] Figure 14 This is a plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the fourth embodiment of the present disclosure.

[0182] Reference Figure 14 Since the secondary battery according to the fourth embodiment has the same structure as the secondary battery according to the first embodiment except for the current collector 300, redundant descriptions of the same components will be omitted.

[0183] In this embodiment, the first current collector 310 and the second current collector 330 can be arranged symmetrically with respect to the virtual center point of the upper surface of the electrode assembly 500.

[0184] In the first embodiment described above, the first current collector 310 and the second current collector 330 can be arranged symmetrically with respect to a central axis parallel to the thickness direction (x-axis direction). In this embodiment, unlike the above, the first current collector 310 and the second current collector 330 can be arranged symmetrically with respect to a virtual center point on the upper surface of the electrode assembly 500.

[0185] In other words, when the first current collector 310 rotates 180 degrees around the virtual center point of the upper surface of the electrode assembly 500, it can overlap with the second current collector 330. Alternatively, when the second current collector 330 rotates 180 degrees around the virtual center point of the upper surface of the electrode assembly 500, it can overlap with the first current collector 310.

[0186] The secondary battery according to the fifth embodiment of this disclosure will be described below.

[0187] Figure 15 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the fifth embodiment of the present disclosure.

[0188] Reference Figure 15 Apart from the current collector 300 and the electrode assembly 500, the secondary battery according to the fifth embodiment has the same structure as the secondary battery according to the first embodiment described above, and therefore redundant descriptions of the same components will be omitted. Furthermore, since the second current collector 330 has the same structure as the first current collector 310, its detailed description will also be omitted.

[0189] In this embodiment, the electrode assembly 500 may include two electrode assemblies, namely the first electrode assembly 510 and the second electrode assembly 520.

[0190] The first branch 313 and the second branch 315 of the first current collector 310 can be connected to the same number of first electrode tab bundles. That is, each of the first branch 313 and the second branch 315 can be connected to one first electrode tab bundle. The first electrode tab bundle 11a can be connected to the upper surface of the first branch 313, and the first electrode tab bundle 11b can be connected to the upper surface of the second branch 315.

[0191] In this configuration, the first branch 313 and the second branch 315 can have the same width. Therefore, the area of ​​the first electrode patch bundle 11a connected to the upper surface of the first branch 313 and the area of ​​the first electrode patch bundle 11b connected to the upper surface of the second branch 315 can be the same. Thus, the branches of the first current collector 310 can be configured to be symmetrical with respect to an axis parallel to the width direction (y-axis direction).

[0192] exist Figure 15 In this configuration, the first electrode tab bundle 11a can be bent downwards from the upper side of the electrode assembly 500 and connected to the upper surface of the first branch 313, and the first electrode tab bundle 11b can be bent upwards from the lower side of the electrode assembly 500 and connected to the upper surface of the second branch 315. That is, the first electrode tab bundles 11a and 11b can be bent in a direction facing each other and connected to the upper surfaces of the first branch 313 and the second branch 315. Preferably, the first current collector 310 is designed such that the first electrode tab bundles 11a and 11b can both protrude from the center portion of the respective electrode assembly in the thickness direction and connect to the respective branch. Figure 15 In the example shown, the width of the first current collector 310 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the first electrode assembly 510 and the second electrode assembly 520. The spacing between the first branch 313 and the second branch 315 in the thickness direction is set as large as possible, as long as it can ensure that the first electrode tab bundle 11a is connected to the first branch 313 and the first electrode tab bundle 11b is connected to the second branch 315.

[0193] The secondary battery according to the sixth embodiment of this disclosure will be described below.

[0194] Figure 16 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to a sixth embodiment of the present disclosure.

[0195] Reference Figure 16Except for the current collector 300 and the electrode assembly 500, the secondary battery according to the sixth embodiment has the same structure as the secondary battery according to the first embodiment described above, and therefore redundant descriptions of the same components will be omitted. Furthermore, since the second current collector 330 has the same structure as the first current collector 310, its detailed description will also be omitted.

[0196] In this embodiment, the electrode assembly 500 may include a first electrode assembly 510, a second electrode assembly 520, a third electrode assembly 530, and a fourth electrode assembly 540, i.e., four electrode assemblies 500. The four electrode assemblies may be stacked and arranged in parallel with each other.

[0197] The first branch 313 and the second branch 315 of the first current collector 310 can be connected to the same number of first electrode tab bundles. Two first electrode tab bundles 11a and 11b can be connected to the first branch 313, and two first electrode tab bundles 11c and 11d can be connected to the second branch 315.

[0198] On the upper surface of the first branch 313, the first electrode tab bundle 11a can be bent downwards from the top and connected to the upper surface of the first branch 313, and the first electrode tab bundle 11b can be bent upwards from the bottom and connected to the upper surface of the first branch 313. That is, the first electrode tab bundle 11a and the first electrode tab bundle 11b can be bent and connected to the upper surface of the first branch 313 in a direction facing each other.

[0199] On the upper surface of the second branch 315, the first electrode tab bundle 11c can be bent downwards from the top and connected to the upper surface of the second branch 315, and the first electrode tab bundle 11d can be bent upwards from the bottom and connected to the upper surface of the second branch 315. That is, the first electrode tab bundle 11c and the first electrode tab bundle 11d can be bent and connected to the upper surface of the second branch 315 in a direction facing each other.

[0200] In addition, the first electrode patch bundles 11a, 11b, 11c and 11d can be arranged in a row along the thickness direction (x-axis direction). That is, when viewed along the thickness direction (x-axis direction), the first electrode patch bundles 11a, 11b, 11c and 11d can be arranged to overlap each other.

[0201] In this configuration, the first branch 313 and the second branch 315 can have the same width. Therefore, the areas of the first electrode tab bundles 11a and 11b connected to the upper surface of the first branch 313 and the areas of the first electrode tab bundles 11c and 11d connected to the upper surface of the second branch 315 can be the same. Therefore, the first current collector 310 can be arranged symmetrically with respect to an axis parallel to the width direction (y-axis direction). Preferably, the first current collector 310 is designed such that the first electrode tab bundles 11a, 11b, 11c, and 11d can all protrude from the center portion of the respective electrode assembly in the thickness direction and connect to the corresponding branch of the first current collector 310. Figure 16 In the example shown, the first electrode tab bundles 11a and 11b are connected to the first branch 313. The width of the first branch 313 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the first electrode assembly 510 and the second electrode assembly 520, so that the first electrode tab bundles 11a and 11b protrude from the center portions of the first electrode assembly 510 and the second electrode assembly 520 in the thickness direction and are connected to the first branch 313, respectively. The first electrode tab bundles 11c and 11d are connected to the second branch 315. The width of the second branch 315 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the third electrode assembly 530 and the fourth electrode assembly 540, so that the first electrode tab bundles 11c and 11d protrude from the center portions of the third electrode assembly 530 and the fourth electrode assembly 540 in the thickness direction and are connected to the second branch 315, respectively. Furthermore, the distance between the first branch 313 and the second branch 315 is greater than or equal to half the sum of the thicknesses of the second electrode assembly 520 and the third electrode assembly 530.

[0202] The secondary battery according to the seventh embodiment of this disclosure will be described below.

[0203] Figure 17 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the seventh embodiment of the present disclosure.

[0204] Reference Figure 17 Except for the current collector 300 and the electrode assembly 500, the secondary battery according to the seventh embodiment has the same structure as the secondary battery according to the sixth embodiment described above, and therefore redundant descriptions of the same components will be omitted. Furthermore, since the second current collector 330 has the same structure as the first current collector 310, its detailed description will also be omitted.

[0205] In this embodiment, the electrode assembly 500 may include a first electrode assembly 510, a second electrode assembly 520, a third electrode assembly 530, a fourth electrode assembly 540, and a fifth electrode assembly 550, i.e., five electrode assemblies. The five electrode assemblies may be stacked and arranged in parallel with each other.

[0206] The first current collector 310 may include a first branch 313, a second branch 315, and a third branch 319. The widths of the first branch 313 and the second branch 315 may be the same, and the third branch 319 may be formed to have a width smaller than that of the first branch 313 and the second branch 315.

[0207] Each of the first branch 313 and the second branch 315 can be connected to two first electrode tab bundles, and the third branch 319 can be connected to one first electrode tab bundle. First electrode tab bundles 11a and 11b can be connected to the upper surface of the first branch 313, and first electrode tab bundles 11c and 11d can be connected to the upper surface of the second branch 315. First electrode tab bundle 11e can be connected to the upper surface of the third branch 319.

[0208] On the upper surface of the first branch 313, the first electrode tab bundle 11a can be bent downwards from the top and connected to the upper surface of the first branch 313, and the first electrode tab bundle 11b can be bent upwards from the bottom and connected to the upper surface of the first branch 313. That is, the first electrode tab bundle 11a and the first electrode tab bundle 11b can be bent and connected to the upper surface of the first branch 313 in a direction facing each other.

[0209] On the upper surface of the second branch 315, the first electrode tab bundle 11c can be bent downwards from the top and connected to the upper surface of the second branch 315, and the first electrode tab bundle 11d can be bent upwards from the bottom and connected to the upper surface of the second branch 315. That is, the first electrode tab bundle 11c and the first electrode tab bundle 11d can be bent and connected to the upper surface of the second branch 315 in a direction facing each other.

[0210] On the upper surface of the third branch 319, the first electrode tab bundle 11e can be bent upward from the lower side and connected to the upper surface of the third branch 319. However, the first electrode tab bundle 11e can be bent downward from the upper side and connected to the upper surface of the third branch 319, but is not limited to this.

[0211] Furthermore, the first electrode tab bundles 11a, 11b, 11c, 11d, and 11e can be arranged in a row along the thickness direction (x-axis direction). That is, when viewed along the thickness direction (x-axis direction), the first electrode tab bundles 11a, 11b, 11c, 11d, and 11e can be arranged to overlap each other. Preferably, the first current collector 310 can be designed such that the first electrode tab bundles 11a, 11b, 11c, 11d, and 11e can all protrude from the center portion of the corresponding electrode assembly in the thickness direction and connect to the corresponding branch of the first current collector 310. The width of the first branch 313 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the first electrode assembly 510 and the second electrode assembly 520, so that the first electrode tab bundles 11a and 11b protrude from the center portion of the first electrode assembly 510 and the second electrode assembly 520 in the thickness direction and connect to the first branch 313, respectively. The width of the second branch 315 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the third electrode assembly 530 and the fourth electrode assembly 540, so that the first electrode tab bundles 11c and 11d protrude from the center portions of the third electrode assembly 530 and the fourth electrode assembly 540 in the thickness direction and connect to the second branch 315, respectively. The spacing between the first branch 313 and the second branch 315 in the thickness direction (x-axis direction) is greater than or equal to half the sum of the thicknesses of the second electrode assembly 520 and the third electrode assembly 530. While ensuring reliable connection between the first electrode tab bundle 11e and the third branch 319, the width of the third branch 319 in the thickness direction (x-axis direction) can be as small as possible, and the spacing between the second branch 315 and the third branch 319 in the thickness direction (x-axis direction) can be greater than half the thickness of the fourth electrode assembly 540 and less than half the sum of the thicknesses of the fourth electrode assembly 540 and the fifth electrode assembly 550. The distance between the first branch 313 and the second branch 315 in the thickness direction (x-axis direction) is greater than the distance between the second branch 315 and the third branch 319 in the thickness direction (x-axis direction).

[0212] The eighth embodiment of the secondary battery according to this disclosure will be described below.

[0213] Figure 18 This is a partial plan view illustrating the state in which the current collector is connected to a plurality of electrode assemblies according to the eighth embodiment of the present disclosure.

[0214] Reference Figure 18Except for the current collector 300 and the electrode assembly 500, the secondary battery according to the eighth embodiment has the same structure as the secondary battery according to the seventh embodiment described above, therefore redundant descriptions of the same components will be omitted. Furthermore, since the second current collector 330 has the same structure as the first current collector 310, its detailed description will also be omitted.

[0215] In this embodiment, the electrode assembly 500 may include a first electrode assembly 510, a second electrode assembly 520, a third electrode assembly 530, a fourth electrode assembly 540, a fifth electrode assembly 550, and a sixth electrode assembly 560, i.e., six electrode assemblies. The six electrode assemblies may be stacked and arranged in parallel with each other.

[0216] The first branch 313, the second branch 315, and the third branch 319 of the first current collector 310 can be connected to the same number of first electrode tab bundles. Each of the first branch 313 to the third branch 319 can be connected to two first electrode tab bundles.

[0217] The first electrode tab bundles 11e and 11f can be connected to the upper surface of the third branch 319. The first electrode tab bundle 11e can be bent downward from the top and connected to the upper surface of the third branch 319, and the first electrode tab bundle 11f can be bent upward from the bottom and connected to the upper surface of the third branch 319.

[0218] In this configuration, the first branch 313, the second branch 315, and the third branch 319 can have the same width. Consequently, the areas of the first electrode tab bundles 11a and 11b connected to the upper surface of the first branch 313, the areas of the first electrode tab bundles 11c and 11d connected to the upper surface of the second branch 315, and the areas of the first electrode tab bundles 11e and 11f connected to the upper surface of the third branch 319 can all be the same. Therefore, the branches of the first current collector 310 can be arranged symmetrically with respect to an axis parallel to the width direction (y-axis direction). Preferably, the first current collector 310 can be designed such that the first electrode tab bundles 11a, 11b, 11c, 11d, 11e, and 11f can all protrude from the center portion of the respective electrode assembly in the thickness direction and connect to the corresponding branch of the first current collector 310. The width of the first branch 313 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the first electrode assembly 510 and the second electrode assembly 520; the width of the second branch 315 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the third electrode assembly 530 and the fourth electrode assembly 540; and the width of the third branch 319 in the thickness direction (x-axis direction) is less than half the sum of the thicknesses of the fifth electrode assembly 550 and the sixth electrode assembly 560. The spacing between the first branch 313 and the second branch 315 is greater than or equal to half the sum of the thicknesses of the second electrode assembly 520 and the third electrode assembly 530, and the spacing between the second branch 315 and the third branch 319 is greater than or equal to half the sum of the thicknesses of the fourth electrode assembly 540 and the fifth electrode assembly 550.

[0219] The secondary battery according to the ninth embodiment of this disclosure will be described below.

[0220] Figure 19 This is a perspective view of the exhaust portion according to the ninth embodiment of this disclosure, viewed from below.

[0221] Reference Figure 19 Except for the exhaust section 50, the secondary battery according to the ninth embodiment has the same structure as the secondary battery according to the first embodiment described above, so redundant descriptions of the same components will be omitted.

[0222] In this embodiment, the secondary battery 10 may be a prismatic battery having a generally cuboid-shaped casing 100, and the venting portion 50 may be fixed to the bottom 100a of the casing 100. The bottom 100a of the casing 100 may be integrally formed with the casing 100, or may be fixed to the casing 100 by welding or the like.

[0223] An exhaust port for discharging gas can be formed in the bottom 100a of the housing 100, the exhaust portion 50 can be inserted into the lower outer side of the exhaust port, and an exhaust protection film 60 can be provided on the lower outer side of the exhaust portion 50.

[0224] The exhaust portion 50 can be formed in the shape of a plate and can be fixed to the housing 100 by welding. The exhaust portion 50 can extend relatively long in the width direction (y-axis direction) of the bottom of the housing.

[0225] The exhaust portion 50 may include two side recesses 52 and 53 and a connecting recess 51 connecting the side recesses 52 and 53. Since the connecting recess 51 and the side recesses 52 and 53 have the same structure as the connecting recess and side recesses according to the first embodiment described above, their redundant description will be omitted.

[0226] Meanwhile, the exhaust protection membrane 60 can be installed at the lower part of the exhaust section 50. The exhaust protection membrane 60 can be formed of a flexible membrane, and connection holes for releasing pressure can be formed in the exhaust protection membrane 60.

[0227] As described above, according to the ninth embodiment, since the exhaust portion 50 is formed at the bottom 100a of the housing 100, the electrolyte can also be discharged together when the exhaust portion 50 is opened.

[0228] The secondary battery according to the tenth embodiment of this disclosure will be described below.

[0229] Figure 20 This illustration shows a perspective view of a secondary battery according to the tenth embodiment of this disclosure, and Figure 21 The illustration shows the view from above. Figure 20 A plan view of a secondary battery.

[0230] Reference Figure 20 and Figure 21 Except for the exhaust section 50, the secondary battery according to the tenth embodiment has the same structure as the secondary battery according to the first embodiment described above, so redundant descriptions of the same components will be omitted.

[0231] In this embodiment, the exhaust portion 50 may extend relatively long in the thickness direction (x-axis direction). The exhaust portion 50 may have a shape that extends in the thickness direction (x-axis direction), such as a rectangular shape, a square shape, or a rounded rectangle shape. In the first embodiment described above, the exhaust portion 50 is formed to extend relatively long in the width direction (y-axis direction), while in this embodiment, the exhaust portion 50 is formed to extend relatively long in the thickness direction (x-axis direction), which intersects the direction of the exhaust portion 50 in the first embodiment. The exhaust portion 50 may be configured such that the longitudinal axis of the exhaust portion 50 intersects the width direction (y-axis direction) (it may be perpendicular to the width direction or not perpendicular to the width direction).

[0232] The exhaust portion 50 can be fixed to the cover plate 21 by welding. The exhaust portion 50 can be fixed to the lower surface of the cover plate 21, or alternatively fixed to the upper surface of the cover plate 20.

[0233] In this embodiment, as multiple electrode assemblies 500 are stacked and the thickness of the cover plate 21 increases in a direction parallel to the thickness direction (x-axis direction), the exhaust portion 50 can be arranged along the thickness direction (x-axis direction). Thus, during gas emission, the exhaust portion 50 is not disturbed by the first current collector 310 and the second current collector 330 positioned below, and therefore the exhaust portion 50 can smoothly emit gas.

[0234] The secondary battery according to the eleventh embodiment of this disclosure will be described below.

[0235] Figure 22 This is a perspective view of the exhaust portion according to the eleventh embodiment of the present disclosure, viewed from below.

[0236] Reference Figure 22 Except for the exhaust section 50, the secondary battery according to the eleventh embodiment has the same structure as the secondary battery according to the tenth embodiment described above, so redundant descriptions of the same components will be omitted.

[0237] In this embodiment, the secondary battery 10 may be a prismatic battery having a generally cuboid-shaped casing 100, and the venting portion 50 may be fixed to the bottom 100a of the casing 100. The bottom 100a of the casing 100 may be integrally formed with the casing 100, or may be fixed to the casing 100 by welding or the like.

[0238] An exhaust port for discharging gas can be formed in the bottom 100a of the housing 100, the exhaust portion 50 can be inserted into the lower outer side of the exhaust port, and the exhaust protective film 60 can be disposed on the lower outer side of the exhaust portion 50.

[0239] The exhaust section 50 can be formed in the shape of a plate and can be fixed to the housing 100 by welding.

[0240] The exhaust portion 50 may extend relatively long in the thickness direction (x-axis direction). The exhaust portion 50 may have a shape that extends in the thickness direction (x-axis direction), such as a rectangular shape, a square shape, or a rounded rectangular shape.

[0241] Meanwhile, the exhaust protection membrane 60 can be installed below the exhaust section 50. The exhaust protection membrane 60 can be formed of a flexible membrane, and connection holes for releasing pressure can be formed in the exhaust protection membrane 60.

[0242] According to one embodiment of this disclosure, a secondary battery can increase its energy density per unit volume by reducing the space occupied by electrode contacts and the like within the casing.

[0243] Furthermore, according to one embodiment of this disclosure, during the process of delivering current to the electrode assembly through external terminals, the secondary battery can reduce the current resistance caused by the increase in the length of the electrode contacts.

[0244] Furthermore, according to one embodiment of this disclosure, as the number of electrode assemblies increases, the secondary battery can stably connect the electrode contacts to the current collector.

[0245] Although this disclosure has been described with respect to specific embodiments, it will be apparent to those skilled in the art that various changes or modifications may be made to this disclosure by adding, altering or deleting components without departing from the spirit of this disclosure as defined in the appended claims.

Claims

1. A secondary battery, comprising: shell; Multiple electrode assemblies are housed within the housing, each electrode assembly having a bundle of electrode tabs; Current collector, the current collector being connected to the electrode tab bundle of the plurality of electrode assemblies; as well as A cover assembly that seals the opening of the housing and has an external terminal for connection with the current collector. The current collector includes: Main support plate, wherein a connecting terminal for connection to the external terminal is positioned on the main support plate; and Multiple branches extend from the side of the main support plate along the width direction of the electrode assembly and are spaced apart from each other in the thickness direction of the electrode assembly. Each of the multiple branches is respectively connected to one or two electrode tab bundles of the electrode tab bundles of the multiple electrode assemblies.

2. The secondary battery according to claim 1, wherein, The electrode patch bundle is formed by stacking the protruding, uncoated portions of the electrodes of the electrode assembly in the thickness direction and performing a first weld.

3. The secondary battery according to claim 2, wherein, The ends of the electrode tab bundle are fixed to the corresponding branches of the plurality of branches by a second welding.

4. The secondary battery according to claim 3, wherein, The second welded area formed at the end by the second weld overlaps at least partially with the first welded area formed at the end by the first weld.

5. The secondary battery according to claim 4, wherein, The second welding area is located within the first welding area.

6. The secondary battery according to claim 3, wherein, The area of ​​the first welded region formed at the end by the first weld is 1.1 to 5 times the area of ​​the second welded region formed at the end by the second weld.

7. The secondary battery according to claim 6, wherein, In the width direction, the length of the first welding area is greater than the length of the second welding area.

8. The secondary battery according to claim 1, wherein, The plurality of branches include a first branch and a second branch that are spaced apart from each other in the thickness direction of the electrode assembly.

9. The secondary battery according to claim 8, wherein, The first branch and the second branch are respectively connected to different numbers of the electrode tab bundles.

10. The secondary battery according to claim 9, wherein, The first branch is connected to two electrode tab bundles, and the second branch is connected to one electrode tab bundle.

11. The secondary battery according to claim 10, wherein, The two electrode patch bundles and the one electrode patch bundle are arranged in a row along the thickness direction.

12. The secondary battery according to claim 11, wherein: The two electrode tab bundles bend toward each other along the thickness direction and are connected to the first branch, and The electrode patch bundle is bent in the same direction as the adjacent electrode patch bundle of the two electrode patch bundles and connected to the second branch.

13. The secondary battery according to claim 12, wherein: The plurality of electrode assemblies includes three electrode assemblies arranged in parallel along the thickness direction, and Each of the three electrode assemblies is provided with one of the electrode tab bundles.

14. The secondary battery according to claim 10, wherein, In the thickness direction, the first width of the first branch is greater than the second width of the second branch.

15. The secondary battery according to claim 14, wherein, The first width of the first branch and the second width of the second branch satisfy the following equation 1: [Formula 1] 1 / 3*C1 ≤ C2 ≤ 1 / 1.5*C1 Wherein, C1 represents the first width, and C2 represents the second width.

16. The secondary battery according to claim 15, wherein, The first area of ​​the first branch and the second area of ​​the second branch satisfy the following equation 2: [Equation 2] 1 / 3*S1 ≤ S2 ≤ 1 / 1.5*S1 Wherein, S1 represents the first area, and S2 represents the second area.

17. The secondary battery according to claim 14, wherein, The spacing between the first branch and the second branch in the thickness direction satisfies the following equation 3: [Formula 3] 1 / 2*C2 ≤ CD ≤ C1 Wherein, C1 represents the first width, C2 represents the second width, and CD represents the interval distance between the first branch and the second branch.

18. The secondary battery according to claim 8, wherein, The electrode tab bundles of the plurality of electrode assemblies are respectively connected to the upper surface of the first branch and the upper surface of the second branch.

19. The secondary battery according to claim 8, wherein, The first branch and the second branch are each connected to the same number of electrode tab bundles.

20. The secondary battery according to claim 1, wherein, The connection terminal is configured to be adjacent to the side end of the electrode assembly in the width direction.

21. The secondary battery according to claim 1, wherein, The connecting terminal has a cylindrical shape.

22. The secondary battery according to claim 1, wherein, The main support plate and the plurality of branches are located in the same plane.

23. The secondary battery according to claim 22, wherein, The flatness of the main support plate and the plurality of branches is 0.05 to 2.

24. The secondary battery according to claim 1, wherein, In the width direction, the total length of the current collector is 0.5 to 0.75 times the length of the electrode assembly.

25. The secondary battery according to claim 1, wherein, The secondary battery also includes an insulation retainer that supports the current collector and is connected to the current collector.

26. The secondary battery according to claim 1, wherein: A portion of the electrode patch bundle is held by an insulating tape and bent toward the upper surface of the electrode assembly, and The insulating tape is disposed between the current collector and a portion of the electrode tab bundle.

27. The secondary battery according to claim 1, It also includes an exhaust portion formed in the housing or the cover assembly. in, The longitudinal axis of the exhaust section is parallel to or intersects the width direction.

28. The secondary battery according to claim 25, wherein, The side of the insulation retainer is formed with a notch, such that a portion of the side surface of the current collector supported in the insulation retainer is exposed through the notch.

29. The secondary battery according to claim 3, wherein, In the direction in which the electrode tab bundle protrudes from the electrode assembly, the edge of the first welding area formed at the end by the first welding is flush with or spaced apart from the edge of the end.

30. The secondary battery according to claim 8, wherein, The plurality of branches also includes a third branch, which is connected to one or two electrode tab bundles.

31. The secondary battery according to any one of claims 1-30, wherein, The current collector is connected on the plurality of electrode assemblies such that the edge of each of the plurality of branches extending parallel to the width direction of the plurality of electrode assemblies is close to the center portion of the corresponding electrode assembly in the thickness direction.

32. The secondary battery according to any one of claims 1-30, wherein, The width of the branch connecting the two electrode tab bundles is less than half the sum of the thicknesses of the two electrode assemblies corresponding to the two electrode tab bundles.

33. The secondary battery according to any one of claims 1-30, wherein, The spacing in the thickness direction between adjacent branches of the plurality of branches that are each connected to two electrode tab bundles is greater than the spacing in the thickness direction between adjacent branches of the plurality of branches that are each connected to a different number of electrode tab bundles.

34. The secondary battery according to any one of claims 1-30, wherein, Each of the electrode tab bundles includes a positive electrode tab bundle and a negative electrode tab bundle spaced apart from each other in the width direction, the current collector includes a first current collector and a second current collector spaced apart from each other in the width direction, and the external terminal includes a first external terminal and a second external terminal; The positive electrode tabs of the plurality of electrode assemblies are connected to a plurality of branches of the first current collector to connect to the first external terminal, and the negative electrode tabs of the plurality of electrode assemblies are connected to a plurality of branches of the second current collector to connect to the second external terminal.

35. The secondary battery according to claim 34, wherein, The first current collector and the second current collector are symmetrically arranged with respect to the central axis of the plurality of electrode assemblies, which is parallel to the thickness direction; or The first current collector and the second current collector are symmetrically arranged with respect to the virtual center point of the surface of the plurality of electrode assemblies on which the electrode tab bundle is disposed.

36. The secondary battery according to claim 34, wherein, The sum of the length of the first current collector in the width direction and the length of the second current collector in the width direction is 0.5 to 0.75 times the length of the electrode assembly.

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