Secondary battery and method for manufacturing thereof

Abstract

The present invention relates to a secondary battery and a method for manufacturing the same. A secondary battery according to an embodiment of the present invention comprises a case, an electrode assembly, a current collector, and a cap assembly. The electrode assembly is housed in the case and has an electrode portion, a plurality of first electrode tabs, and a plurality of second electrode tabs. The current collector has a first current collector, a second current collector, and a connecting portion. The cap assembly is coupled to one end of the case. The plurality of first and second electrode tabs can each be bent and welded onto the first current collector and the second current collector of the current collector.

Description

Technology Field

[0001] The present invention relates to a secondary battery and a method for manufacturing the same, and more specifically, to a secondary battery and a method for manufacturing the same in which a plurality of first electrode tabs and a plurality of second electrode tabs are respectively welded to a first current-collecting part and a second current-collecting part of a current collector. Background Technology

[0002] Recently, with the rapid increase in demand for portable electronic products and the full-scale development of electric vehicles, energy storage batteries, robots, and satellites, research on high-performance secondary batteries capable of repeated charging and discharging is actively underway.

[0003] Secondary batteries can be classified according to the shape of the battery case into can-type secondary batteries, in which the electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which the electrode assembly is embedded in a pouch of aluminum laminate sheets. Can-type secondary batteries can be classified into cylindrical secondary batteries and prismatic secondary batteries depending on the shape of the metal can.

[0004] In a secondary battery, the electrode tab of the electrode assembly is connected to the current collector by welding. When welding the electrode tab and the current collector, the electrode tab is bent in a bending direction to increase the contact area between them, the current collector is placed on the upper side of the electrode tab, and then welding is performed.

[0005] However, in this case, there is a risk that the separator may be damaged during the welding process of the current collector and the electrode tabs located below it. Additionally, as secondary batteries become larger in capacity, the number of electrode tabs that must be welded at once increases; consequently, there is a concern that tabs located far from the current collector may not be properly welded.

[0006] Therefore, there is a need to develop a secondary battery that eliminates concerns about separator damage and can stably weld a large number of electrode tabs to the current collector. The problem to be solved

[0007] The object of the present invention is to provide a secondary battery and a method for manufacturing the same that can prevent the electrode assembly from being affected when welding the electrode tab and the current collector.

[0008] The objective of the present invention is to provide a secondary battery capable of stably welding a large number of electrode tabs to a current collector when welding the electrode tabs and the current collector, and a method for manufacturing the same.

[0009] The objective of the present invention is to provide a secondary battery capable of welding electrode tabs and a current collector so that none of the plurality of electrode tabs are unwelded, and a method for manufacturing the same.

[0010] The object of the present invention is to provide a secondary battery capable of preventing interference between different electrode tab assemblies welded to a current collector at mutually spaced positions, and a method for manufacturing the same. means of solving the problem

[0011] A secondary battery according to one embodiment of the present invention comprises an electrode assembly and a current collector. The electrode assembly may have an electrode portion and a plurality of first electrode tabs and a plurality of second electrode tabs formed at one end of the electrode portion. The current collector may have a first current collector that is disposed on the upper part of the electrode portion and welded to a plurality of first electrode tabs, a second current collector that is welded to a plurality of second electrode tabs, and a connecting portion disposed between the first current collector and the second current collector and having a current collecting projection. A plurality of first electrode tabs may be bent in one direction toward a first current collector of the current collector, and a plurality of second electrode tabs may be bent in a direction opposite to that of the first electrode tabs toward a second current collector of the current collector.

[0012] In a secondary battery according to one embodiment of the present invention, a plurality of first electrode tabs are bent in one direction toward a first current collector of a current collector, and a plurality of second electrode tabs are bent in the opposite direction to the first electrode tabs toward a second current collector of a current collector and can be welded respectively.

[0013] A current collector according to one embodiment of the present invention includes a first surface facing the electrode portion and a second surface opposite to the first surface, and at least a portion may be located between the first electrode tab and the second electrode tab. The first electrode tab and the second electrode tab are positioned at offset positions with respect to each other with the current collector in between, and may be bent toward the second surface and welded to the second surface.

[0014] In a secondary battery according to one embodiment of the present invention, the electrode portion may comprise a plurality of first electrode members having a first electrode tab formed at a first position and a plurality of second electrode members having a second electrode tab formed at a second position. The first electrode members and the second electrode members may have the same polarity.

[0015] In a secondary battery according to one embodiment of the present invention, a plurality of first electrode tabs and a plurality of second electrode tabs may be spaced apart in the width direction (y direction) and length direction (x direction) of the electrode assembly.

[0016] In a secondary battery according to one embodiment of the present invention, a plurality of first electrode tabs can be pre-welded to each other, and a plurality of second electrode tabs can be pre-welded to each other.

[0017] In a secondary battery according to one embodiment of the present invention, a first current collector and a second current collector may be arranged in the longitudinal direction of the electrode assembly.

[0018] A current collector according to one embodiment of the present invention may further include a connecting portion disposed between the first current collector and the second current collector and having a current collecting projection.

[0019] A current collector according to one embodiment of the present invention may further include a current collecting edge disposed on one side of the first current collecting part and having a current collecting projection.

[0020] In a secondary battery according to one embodiment of the present invention, a current collector may be disposed between a plurality of first electrode tabs and a plurality of second electrode tabs.

[0021] In a secondary battery according to one embodiment of the present invention, a protective layer may be disposed on the lower part of the current collector.

[0022] In a secondary battery according to one embodiment of the present invention, the thickness of the current collector may be 0.5 to 3.0 mm.

[0023] A secondary battery according to one embodiment of the present invention may further include a cover member covering the first and second electrode tabs, each welded to a current collector.

[0024] In a secondary battery according to one embodiment of the present invention, the current collecting protrusion may be formed of the same material as the first and second current collecting parts.

[0025] In a secondary battery according to one embodiment of the present invention, the current collecting protrusion may be formed of a material different from the first and second current collecting parts.

[0026] In a secondary battery according to one embodiment of the present invention, the electrode portion may have a separator located between each of a plurality of first electrode members and a plurality of second electrode members. An electrode assembly may be formed by stacking or winding a plurality of first electrode members, a plurality of second electrode members, and a separator.

[0027] A secondary battery according to one embodiment of the present invention may further include a case and a cap assembly. One end of the case is open and may accommodate an electrode assembly. The cap assembly may be coupled to one end of the case and may have an electrode terminal electrically connected to a current collector.

[0028] In a secondary battery according to one embodiment of the present invention, a through hole may be provided in the electrode terminal. A current collecting projection may be inserted into the through hole of the electrode terminal.

[0029] A method for manufacturing a secondary battery according to one embodiment of the present invention comprises: a preparation step in which an electrode assembly is prepared having an electrode portion, a plurality of first electrode tabs and a plurality of second electrode tabs formed at one end of the electrode portion; a first welding step in which a plurality of first electrode tabs are welded to each other and a plurality of second electrode tabs are welded to each other; a current collector placement step in which a current collector is placed between a plurality of first electrode tabs and a plurality of second electrode tabs that have been welded in the first step; a bending step in which a plurality of first electrode tabs are bent toward the upper surface of a first current collector portion of a current collector and a plurality of second electrode tabs are bent toward the upper surface of a second current collector portion of a current collector; and a second welding step in which a plurality of first electrode tabs are welded to a first current collector portion and a plurality of second electrode tabs are welded to a second current collector portion, respectively.

[0030] In a method for manufacturing a secondary battery according to one embodiment of the present invention, a plurality of first electrode tabs and a plurality of second electrode tabs may have the same polarity.

[0031] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the current collector may have a first current collector and a second current collector arranged in the longitudinal direction of the electrode assembly.

[0032] In a method for manufacturing a secondary battery according to one embodiment of the present invention, a protective layer may be disposed on the lower part of the current collector.

[0033] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the current collector may have a current collecting projection formed of a material different from that of the first current collecting part and the second current collecting part between the first current collecting part and the second current collecting part.

[0034] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the current collector may have a current collecting projection formed of the same material as the first current collecting part and the second current collecting part between the first current collecting part and the second current collecting part.

[0035] A secondary battery according to an embodiment of the present invention comprises: a plurality of first electrode members, each comprising a first electrode tab; a plurality of second electrode members, each comprising a second electrode tab; a plurality of third electrode members, each comprising a third electrode tab; a plurality of fourth electrode members, each comprising a fourth electrode tab; a first stack portion formed by stacking the plurality of first electrode members and the plurality of second electrode members, having a length in a first direction and a width in a second direction perpendicular to the first direction; an electrode assembly formed by stacking the plurality of third electrode members and the plurality of fourth electrode members, and including the first stack portion and the second stack portion stacked in the second direction; a first electrode tab assembly formed by combining the first electrode tab of each of the plurality of first electrode members to form the first stack portion and located in a first region among a plurality of regions of the electrode assembly divided in the first direction; and a second electrode tab formed by combining the second electrode tab of each of the plurality of second electrode members to form the first stack portion and located in a second region different from the first region among a plurality of regions of the electrode assembly divided in the first direction. It may include a second electrode tab assembly.

[0036] A secondary battery according to one embodiment of the present invention may include a plurality of first electrode members, each comprising a first electrode tab.

[0037] A secondary battery according to one embodiment of the present invention may include a plurality of second electrode members, each having a second electrode tab and having the same polarity as the plurality of first electrode members.

[0038] A secondary battery according to one embodiment of the present invention may include an electrode assembly formed by stacking the plurality of first electrode members and the plurality of second electrode members, having a length in a first direction and a width in a second direction perpendicular to the first direction.

[0039] A secondary battery according to one embodiment of the present invention may include a terminal for connecting the electrode assembly to an external device.

[0040] A secondary battery according to one embodiment of the present invention may include a first current collector, a second current collector spaced apart from the first current collector in the first direction, and a current collector including a current collecting projection formed between the first current collector and the second current collector and connected to the terminal.

[0041] According to one embodiment of the present invention, the first electrode tab of each of the plurality of first electrode members is bent in the second direction and welded to the first current collector, and the second electrode tab of each of the plurality of second electrode members is bent in the second direction and welded to the second current collector, and the current collector projection may be located between the first electrode tab and the second electrode tab.

[0042] A secondary battery according to one embodiment of the present invention may include a first electrode tab assembly formed by joining the first electrode tabs of each of the plurality of first electrode members together and welded to the first current collector.

[0043] A secondary battery according to one embodiment of the present invention may include a second electrode tab assembly welded to a second current collector, wherein the second electrode tabs of each of the plurality of second electrode members are formed by being joined together.

[0044] According to one embodiment of the present invention, at least a portion of the first electrode tab assembly and at least a portion of the second electrode tab assembly can be bent in opposite directions and welded to the current collector.

[0045] According to one embodiment of the present invention, the current collector may include a lower surface facing the electrode assembly.

[0046] According to one embodiment of the present invention, the current collector may include an upper surface facing the terminal.

[0047] According to one embodiment of the present invention, the first electrode tab assembly and the second electrode tab assembly can be welded to the upper surface of the current collector.

[0048] According to one embodiment of the present invention, the first electrode tab assembly may include a first assembly welded portion formed in which the first electrode tabs of each of the plurality of first electrode members are joined together, and a first-1 assembly portion welded to the first current collector.

[0049] According to one embodiment of the present invention, the second electrode tab assembly may include a second assembly welding portion formed in which the second electrode tabs of each of the plurality of second electrode members are joined together, and a second-1 assembly portion welded to the second current collector.

[0050] The first electrode tab assembly according to one embodiment of the present invention may include a first-2 assembly portion located between the first current collector and the electrode assembly.

[0051] The second electrode tab assembly according to one embodiment of the present invention may include a second-2 assembly portion located between the second current collector and the electrode assembly.

[0052] The first electrode tab assembly according to one embodiment of the present invention may include a first-third assembly portion extending in a direction away from the current collector.

[0053] The second electrode tab assembly according to one embodiment of the present invention may include a second-third assembly portion extending in a direction away from the current collector.

[0054] According to one embodiment of the present invention, the current collector may include a connecting portion having at least a portion located between the first electrode tab and the second electrode tab, and having a current collecting projection protruding therefrom.

[0055] According to one embodiment of the present invention, the first electrode tab and the second electrode tab may be spaced apart from each other along the first direction.

[0056] The electrode assembly according to one embodiment of the present invention may include a bridge portion formed between the first electrode tab and the second electrode tab.

[0057] According to one embodiment of the present invention, the current collection projection may protrude toward the terminal at a position corresponding to the bridge portion.

[0058] A secondary battery according to one embodiment of the present invention may include a plurality of second electrode members, each comprising a second electrode tab.

[0059] A secondary battery according to one embodiment of the present invention may include an electrode assembly having a length in a first direction and a width in a second direction perpendicular to the first direction, a first stack portion formed by stacking a plurality of first electrode members, and a second stack portion formed by stacking a plurality of second electrode members and stacked in the first stack portion and the second direction.

[0060] A secondary battery according to one embodiment of the present invention may include a first electrode tab assembly formed in a first stack portion by combining the first electrode tabs of each of the plurality of first electrode members, and located in a first region among a plurality of regions of the electrode assembly separated in the first direction.

[0061] A secondary battery according to one embodiment of the present invention may include a second electrode tab assembly formed in the second stack portion by combining the second electrode tabs of each of the plurality of second electrode members, and located in a second region different from the first region among the plurality of regions of the electrode assembly separated in the first direction.

[0062] According to one embodiment of the present invention, at least a portion of the first electrode tab assembly and at least a portion of the second electrode tab assembly may be non-overlapping in the first direction.

[0063] According to one embodiment of the present invention, the first electrode tab assembly and the second electrode tab assembly may be non-overlapping in the second direction.

[0064] A secondary battery according to one embodiment of the present invention may include a current collector welded to the first electrode tab assembly and the second electrode tab assembly.

[0065] The electrode assembly according to one embodiment of the present invention may include a bridge portion formed between the first electrode tab assembly and the second electrode tab assembly, which are spaced apart from each other, and facing at least a portion of the current collector.

[0066] The first electrode tab assembly according to one embodiment of the present invention may include a first-1 assembly portion bent toward the second stack portion.

[0067] The second electrode tab assembly according to one embodiment of the present invention may include a second-1 assembly portion bent toward the first stack portion.

[0068] A secondary battery according to one embodiment of the present invention may include a first electrode tab assembly formed by welding the first electrode tabs of each of the plurality of first electrode members together.

[0069] A secondary battery according to one embodiment of the present invention may include a second electrode tab assembly formed by welding together the second electrode tabs of each of the plurality of second electrode members.

[0070] A secondary battery according to one embodiment of the present invention may include a current collector to which the first electrode tab assembly and the second electrode tab assembly are welded.

[0071] The first electrode tab assembly according to one embodiment of the present invention may include a first assembly weld portion formed by welding the first electrode tabs of each of the plurality of first electrode members together.

[0072] The first electrode tab assembly according to one embodiment of the present invention may include a first current collector weld portion formed by welding to the current collector.

[0073] The second electrode tab assembly according to one embodiment of the present invention may include a second assembly weld portion formed by welding the second electrode tabs of each of the plurality of second electrode members together.

[0074] The second electrode tab assembly according to one embodiment of the present invention may include a second current collector weld portion formed by welding to the current collector.

[0075] The first electrode tab assembly according to one embodiment of the present invention may include a first-1 assembly portion in which the first assembly welding portion and the first current collector welding portion are formed.

[0076] The second electrode tab assembly according to one embodiment of the present invention may include a second-1 assembly portion in which the second assembly welding portion and the second current collector welding portion are formed.

[0077] A secondary battery according to one embodiment of the present invention may include an electrode assembly formed by stacking the plurality of first electrode members and the plurality of second electrode members.

[0078] The first electrode tab assembly according to one embodiment of the present invention may include a first-2 assembly portion located between the first current collector welding portion and the electrode assembly.

[0079] The second electrode tab assembly according to one embodiment of the present invention may include a second-2 assembly portion located between the second current collector welding portion and the electrode assembly.

[0080] According to one embodiment of the present invention, the current collector may include a first current collector located between the first current collector welding portion and the first-second assembly portion.

[0081] According to one embodiment of the present invention, the current collector may include a second current collector located between the second current collector welding portion and the second-2 assembly portion.

[0082] According to one embodiment of the present invention, the current collector may include a lower surface facing the electrode assembly.

[0083] According to one embodiment of the present invention, the current collector may include a first welded surface facing in a direction opposite to the lower surface and in which the first assembly welded portion and the first current collector welded portion are joined.

[0084] According to one embodiment of the present invention, the current collector may include a second welding surface facing in a direction opposite to the lower surface and in which the second assembly welding portion and the second current collector welding portion are joined.

[0085] A secondary battery according to one embodiment of the present invention may include an electrode assembly formed by stacking the plurality of first electrode members and the plurality of second electrode members.

[0086] A secondary battery according to one embodiment of the present invention may include a current collector having a first surface facing the electrode assembly and a second surface opposite to the first surface, at least a portion of which is located between the first electrode tab and the second electrode tab.

[0087] According to one embodiment of the present invention, the first electrode tab and the second electrode tab may be welded to the second surface at offset positions relative to the current collector.

[0088] According to one embodiment of the present invention, the first electrode tab assembly and the second electrode tab assembly may be welded to the second surface at positions that do not overlap each other in the width direction of the current collector.

[0089] The current collector according to one embodiment of the present invention may include a first welding surface forming at least a portion of the second surface.

[0090] According to one embodiment of the present invention, the current collector may include a second welding surface that forms at least a portion of the second surface and is spaced apart from the first welding surface.

[0091] According to one embodiment of the present invention, the first electrode tab assembly may be welded to the first welding surface, and the second electrode tab assembly may be welded to the second welding surface.

[0092] A secondary battery according to one embodiment of the present invention may include an insulating member that covers at least a portion of the first-1 assembly portion and at least a portion of the second-1 assembly portion, with at least a portion disposed between the current collector and the electrode assembly.

[0093] The current collector according to one embodiment of the present invention may include a current collecting projection formed between the first and second electrode tabs and the edge of the electrode assembly.

[0094] A secondary battery according to one embodiment of the present invention may include a cover member that covers the first and second electrode tabs welded to the current collector. Effects of the invention

[0095] The secondary battery and the method for manufacturing the same according to an embodiment of the present invention can prevent damage to the separator during welding of the electrode tab and the current collector.

[0096] The secondary battery and the method for manufacturing the same according to an embodiment of the present invention can prevent unwelded portions from occurring in some electrode tabs when welding a large number of electrode tabs and current collectors.

[0097] A secondary battery and a method for manufacturing the same according to an embodiment of the present invention can prevent unwelded portions from occurring by primarily welding a plurality of electrode tabs to each other and then secondarily welding them to a current collector.

[0098] A secondary battery and a method for manufacturing the same according to an embodiment of the present invention can prevent interference between a first electrode tab assembly and a second electrode tab assembly by welding the first electrode tab assembly and the second electrode tab assembly, which are welded to the first and second current collection parts of the current collector respectively, to the current collector at positions spaced apart from each other. Brief explanation of the drawing

[0099] FIG. 1 is a drawing showing a secondary battery according to one embodiment of the present invention. FIG. 2 is a drawing showing a secondary battery according to one embodiment of the present invention. FIG. 3 is a drawing showing an electrode assembly having a plurality of first and second electrode tabs formed on an electrode portion in a secondary battery according to one embodiment of the present invention. FIG. 4 is a drawing showing a first electrode member and a second electrode member in a secondary battery according to one embodiment of the present invention. FIG. 5 is a drawing showing a third electrode member and a fourth electrode member in a secondary battery according to one embodiment of the present invention. FIG. 6 is a drawing showing a current collector in a secondary battery according to one embodiment of the present invention. FIG. 7 is a drawing showing a current collector in a secondary battery according to one embodiment of the present invention. FIG. 8 is a flowchart illustrating a method for manufacturing a secondary battery according to one embodiment of the present invention. FIG. 9 is a diagram showing a state in which a plurality of first electrode tabs and a plurality of second electrode tabs are each grouped in a secondary battery according to one embodiment of the present invention. FIG. 10 is a drawing showing a state in which a plurality of first electrode tabs and a plurality of second electrode tabs are each welded in a secondary battery according to one embodiment of the present invention. FIG. 11 is a drawing showing a state in which a current collector is placed between a plurality of first electrode tabs and a plurality of second electrode tabs in a secondary battery according to one embodiment of the present invention. FIG. 12 is a drawing showing the state in which a current collector and first and second electrode tabs are welded in a secondary battery according to one embodiment of the present invention. FIG. 13 is a drawing showing the state in which a cap assembly is combined with an electrode assembly in a secondary battery according to one embodiment of the present invention. FIG. 14 is a flowchart illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. FIG. 15 is a diagram showing a state in which a plurality of first electrode tabs and a plurality of second electrode tabs are each grouped in a secondary battery according to another embodiment of the present invention. FIG. 16 is a cross-sectional view along the F-F' reference line shown in FIG. 15. FIG. 17 is a drawing showing a state in which a current collector is placed between a plurality of first electrode tabs and a plurality of second electrode tabs in a secondary battery according to another embodiment of the present invention. FIG. 18 is a drawing showing the state in which a current collector and first and second electrode tabs are welded in a secondary battery according to another embodiment of the present invention. FIG. 19 is a drawing showing the state in which a cover member is arranged in a secondary battery according to another embodiment of the present invention. FIG. 20 is a cross-sectional view along the G-G' reference line shown in FIG. 19. Specific details for implementing the invention

[0100] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0101] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this invention, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0102] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that in the accompanying drawings, identical components are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the present invention will be omitted. For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically depicted.

[0104] FIG. 1 is a drawing showing a secondary battery according to an embodiment of the present invention, FIG. 2 is a drawing showing a secondary battery according to an embodiment of the present invention, FIG. 3 is a drawing showing an electrode assembly having a plurality of first and second electrode tabs formed on an electrode portion in a secondary battery according to an embodiment of the present invention, FIG. 4 is a drawing showing a first electrode member and a second electrode member in a secondary battery according to an embodiment of the present invention, FIG. 5 is a drawing showing a third electrode member and a fourth electrode member in a secondary battery according to an embodiment of the present invention, FIG. 6 is a drawing showing a current collector in a secondary battery according to an embodiment of the present invention, and FIG. 7 is a drawing showing a current collector in a secondary battery according to an embodiment of the present invention.

[0105] Directions for describing a secondary battery (1000) are defined with reference to FIGS. 1 to 20. A first direction (+X or -X direction) may be defined. The first direction (+X or -X direction) may mean the 'length direction of the secondary battery (1000)'. The first direction (+X or -X direction) may be a direction in which the first electrode tab (1220) and the second electrode tab (1230) are spaced apart from each other. A second direction (+Y or -Y direction) may be defined. The second direction (+Y or -Y direction) may mean the 'width direction of the secondary battery (1000)'. The second direction (+Y or -Y direction) may be a direction in which a plurality of first electrode tabs (1220) are aligned with each other. A third direction (+Z or -Z direction) may be defined. The third direction (+Z or -Z direction) may mean the height direction of the secondary battery (1000). The third direction (+Z or -Z direction) may be the direction in which the current collector (1300) and the cap assembly (1400) are joined.

[0107] As illustrated in FIGS. 1 and 2, a secondary battery (1000) according to one embodiment of the present invention may include a case (1100), an electrode assembly (1200), a current collector (1300), and a cap assembly (1400).

[0108] The case (1100) can form the exterior of the secondary battery (100). The case (1100) may have a space formed inside to accommodate an electrode assembly (1200), and an opening may be formed on one side of the case (1100). In this embodiment, the shape of the case (1100) is a rectangular parallelepiped shape, but it is not limited thereto and can be modified in various ways. The material of the case (1100) may be made of a rigid material capable of protecting the electrode assembly (1200) accommodated inside. For example, the case (1100) may be made of a metal such as aluminum or stainless steel.

[0109] Referring to FIGS. 1 and 2, an electrolyte may be accommodated together with an electrode assembly (1200) inside a case (1100). The electrolyte may consist of a lithium salt such as LiPF6 or LiBF4 in an organic solvent such as EC, PC, DEC, EMC, or DMC. The electrolyte may be in a liquid, solid, or gel form.

[0110] Referring to FIGS. 1, 2, and 3, an electrode assembly (1200) can be accommodated inside a case (1100). As shown in FIG. 3, the electrode assembly (1200) may include an electrode portion (1210), a plurality of first electrode tabs (1220), and a plurality of second electrode tabs (1230). Each of the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) may be disposed at one end of the electrode portion (1210). The plurality of first electrode tabs (1220) are aligned with each other, and the plurality of second electrode tabs (1230) are aligned with each other. A plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230), each aligned, can be arranged so as not to overlap in the width direction (e.g., +Y direction) and length direction (e.g., +X direction) of the electrode assembly (1200). For example, a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) can be non-overlapping in the length direction (+X direction) of the electrode assembly (1200). For example, a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) can be non-overlapping in the width direction (+Y direction) of the electrode assembly (1200). For example, a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) can be dislocated from the length direction (+X direction) of the electrode assembly (1200). For example, a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) may be dislocated from the width direction (+Y direction) of the electrode assembly (1200). The first electrode tabs (1220) and the second electrode tabs (1230) may be placed at offset positions relative to each other.

[0111] Referring to FIGS. 1, 2 and 3, the electrode assembly (1200) may include a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250). Each of the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) may be disposed at one end of the electrode portion (1210). The plurality of third electrode tabs (1240) are aligned with each other, and the plurality of fourth electrode tabs (1250) are aligned with each other. The respective aligned plurality of third electrode tabs (1240) and plurality of fourth electrode tabs (1250) are disposed so as not to overlap in the width direction (e.g., +Y direction) and length direction (e.g., +X direction) of the electrode assembly (1200). For example, a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) may not overlap in the length direction (+X direction) of the electrode assembly (1200). For example, a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) may not overlap in the width direction (+Y direction) of the electrode assembly (1200). For example, a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) may be dislocated from the length direction (+X direction) of the electrode assembly (1200). For example, a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) may be dislocated from the width direction (+Y direction) of the electrode assembly (1200). The third electrode tab (1240) and the fourth electrode tab (1250) can be placed at an offset position from each other.

[0112] Referring to FIGS. 1, 2 and 3, specifically, the electrode portion (1210) may include a plurality of first electrode members (1211), a plurality of second electrode members (1212), a plurality of third electrode members (1213), a plurality of fourth electrode members (1214), and a separator.

[0113] Referring to FIGS. 1, 2, and 3, an active material may be applied to each of the plurality of first electrode members (1211), the plurality of second electrode members (1212), the plurality of third electrode members (1213), and the plurality of fourth electrode members (1214). An active material, such as a transition metal oxide, may be applied to a metal plate such as aluminum on the plurality of first electrode members (1211) and the plurality of second electrode members (1212). The plurality of first electrode members (1211) and the plurality of second electrode members (1212) may have the same polarity and may be positive electrode plates. An active material, such as graphite or carbon, may be applied to a metal plate such as copper or nickel on the plurality of third electrode members (1213) and the plurality of fourth electrode members (1214). The plurality of third electrode members (1213) and the plurality of fourth electrode members (1214) may have the same polarity and may be negative electrode plates.

[0114] Referring to FIGS. 1, 2, and 3, the separator is positioned between a plurality of first to fourth electrode members (1211, 1212, 1213, 1214) to prevent short circuits between the plurality of first to fourth electrode members (1211, 1212, 1213, 1214). The material of the separator may be polyethylene, polypropylene, or a composite thereof.

[0115] Referring to FIGS. 1, 2, and 3, a plurality of first electrode members (1211) and a plurality of third electrode members (1213) may be arranged alternately with respect to each other. For example, a plurality of third electrode members (1213) may be arranged between each of the plurality of first electrode members (1211), and a plurality of first electrode members (1211) may be arranged between each of the plurality of third electrode members (1213). A plurality of first electrode members (1211) and a plurality of third electrode members (1213) may be stacked alternately in the width direction (e.g., +Y direction). An electrode assembly (1200) may include a first stack portion (1205) in which a plurality of first electrode members (1211) and a plurality of third electrode members (1213) are arranged alternately with respect to each other. The first stack portion (1205) may be a part of the electrode assembly (1200). A plurality of first electrode members (1211) and a plurality of third electrode members (1213) may be located in the first stack portion (1205).

[0116] Referring to FIGS. 1, 2, and 3, a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) may be arranged alternately with respect to each other. For example, a plurality of fourth electrode members (1214) may be arranged between each of the plurality of second electrode members (1212), and a plurality of second electrode members (1212) may be arranged between each of the plurality of fourth electrode members (1214). A plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) may be stacked alternately in the width direction (e.g., +Y direction). An electrode assembly (1200) may include a second stack portion (1206) in which a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) are arranged alternately with respect to each other. The second stack portion (1206) may be a part of the electrode assembly (1200). A plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) may be located in the second stack portion (1206).

[0117] Referring to FIGS. 1, 2 and 3, the first stack portion (1205) and the second stack portion (1206) can be stacked together. The electrode assembly (1200) may be a structure formed by stacking the first stack portion (1205) and the second stack portion (1206).

[0118] Referring to FIGS. 1, 2 and 3, the first stack portion (1205) and the second stack portion (1206) may each form a part of the electrode assembly (1200). For example, the first stack portion (1205) may be a part of the electrode assembly (1200) located on one side (e.g., -Y direction) with respect to a virtual plane (P4) that crosses the electrode assembly (1200) perpendicular to the width direction (e.g., +Y direction) of the electrode assembly (1200), and the second stack portion (1206) may be the remaining part of the electrode assembly (1200) located on the other side (e.g., +Y direction) with respect to the plane (P4).

[0119] Referring to FIGS. 1, 2 and 3, the first stack portion (1205) may be formed by positioning a separator between a plurality of alternately arranged first electrode members (1211) and a plurality of alternately arranged third electrode members (1213). The second stack portion (1206) may be formed by positioning a separator between a plurality of alternately arranged second electrode members (1212) and a plurality of alternately arranged fourth electrode members (1214). In another embodiment of the present invention, the electrode portion may be formed by stacking the first electrode member (1211), the separator, the third electrode member (1213), the separator, the second electrode member (1212), the separator, the fourth electrode member (1214), and the separator in that order, and then winding. In another embodiment of the present invention, the electrode portion may be formed by stacking the first stack portion (1205) in the order of the first electrode member (1211), the separator, the third electrode member (1213), and the separator, and then winding it, and the second stack portion (1206) may be formed by stacking the second electrode member (1212), the separator, the fourth electrode member (1214), and the separator in the order of the second electrode member (1212), the separator, and then winding it.

[0120] In this embodiment, the electrode assembly (1200) has one electrode part (1210), but in other embodiments, the electrode assembly (1200) may have a plurality of electrode parts (1210). The plurality of electrode parts (1210) may be electrically connected to each other.

[0121] Referring to FIGS. 1, 2 and 3, each of the plurality of first to fourth electrode members (1211, 1212, 1213, 1214) may include an electrode tab (1220, 1230, 1240, 1250) on which no active material is applied. The electrode tab (1220, 1230, 1240, 1250) may be at least a part of the uncoated portion formed on each of the plurality of first to fourth electrode members (1211, 1212, 1213, 1214). In one embodiment, the electrode members (1211, 1212, 1213, 1214) and electrode tabs (1220, 1230, 1240, 1250) can be integrally formed by cutting a predetermined portion of a metal member using a laser or the like to leave the electrode members (1211, 1212, 1213, 1214) and electrode tabs (1220, 1230, 1240, 1250). A plurality of electrode tabs (1220, 1230, 1240, 1250) can be formed in a direction toward the cap assembly (1400).

[0122] The cap assembly (1400) can seal the opening of the case (1100) in which the electrode assembly (1200) is housed. The cap assembly (1400) may include a cap plate (1410) and terminals (1420, 1420a). The terminals (1420, 1420a) can connect the electrode assembly (1200) to an external device.

[0123] Referring to FIGS. 1 and 2, the cap plate (1410) may be in the shape of a plate covering the opening of the case (1100). The cap plate (1410) may have a shape corresponding to the shape of the opening of the case (1100). The cap plate (1410) may be formed from the same material as the case (1100), and the cap plate (1410) may be fixed to the case (1100) by a method such as laser welding.

[0124] Referring to FIGS. 1 and 2, a vent hole (1411) and an electrolyte injection port (1412) may be formed in the cap plate (1410). The vent hole (1411) may be opened when the internal pressure of the case (1100) exceeds a reference value. In this embodiment, the vent hole (1411) is formed in the cap plate (1410), but in other embodiments, the vent hole (1411) may be formed in the case (1100). Electrolyte can be injected into the interior of the case (1100) through the electrolyte injection port (1412).

[0125] Referring to FIGS. 1 and 2, the terminal (1420, 1420a) may be formed protruding from the cap plate (1410). The terminal (1420, 1420a) may be electrically connected to the electrode tab (1220, 1230, 1240, 1250) through the current collector (1300). The terminal (1420, 1420a) may be in the shape of a circular or square plate.

[0126] Referring to FIGS. 1 and 2, a through hole may be formed in the terminal (1420, 1420a). A current collecting projection (1331) may be inserted into the through hole. After the current collecting projection (1331) is inserted into the through hole, the outer surface of the end of the current collecting projection (1331) and the inner surface of the end of the through hole may be welded together.

[0127] An insulating member may be disposed between the terminal (1420, 1420a) and the cap plate (1410). The insulating member may insulate the terminal (1420, 1420a) and the cap plate (1410) from each other.

[0128] Referring to FIG. 3, the electrode assembly (1200) may include a plurality of regions (1201, 1202, 1203, 1204). The plurality of regions (1201, 1202, 1203, 1204) may be arranged in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). Each of the plurality of regions (1201, 1202, 1203, 1204) may be a part of the electrode assembly (1200). Each of the plurality of regions (1201, 1202, 1203, 1204) may be separated from one another by a plurality of planes (P1, P2, P3) perpendicular to the longitudinal direction (+X direction) of the electrode assembly (1200). A plurality of planes (P1, P2, P3) may be virtual planes spaced apart from each other in the longitudinal direction (+X direction) of the electrode assembly (1200) to divide the electrode assembly (1200) into a plurality of regions (1201, 1202, 1203, 1204). For example, the first plane (P1) may divide the electrode assembly (1200) into a first region (1201) and a second region (1202) as a boundary. For example, the second plane (P2) may divide the electrode assembly (1200) into a second region (1202) and a third region (1203) as a boundary. For example, the third plane (P3) may divide the electrode assembly (1200) into a third region (1203) and a fourth region (1204) as a boundary.

[0129] Referring to FIG. 3, each of the first, second, third, and fourth electrode tabs (1220, 1230, 1240, 1250) may be located in different regions of the electrode assembly (1200). The first electrode tab (1220) may be located in the first region (1201). The second electrode tab (1230) may be located in the second region (1202). The third electrode tab (1240) may be located in the third region (1203). The fourth electrode tab (1250) may be located in the fourth region (1204). That is, each of the first, second, third, and fourth electrode tabs (1220, 1230, 1240, 1250) may be located in each of the different regions (1201, 1202, 1203, 1204) separated along the longitudinal direction (e.g., +X direction) of the electrode assembly (1200).

[0130] Referring to FIGS. 3 and 4, the first electrode member (1211) may include a plurality of first electrode portions (12111, 12112, 12113, 12114). The plurality of first electrode portions (12111, 12112, 12113, 12114) may be separated from one another by a plurality of planes (P1, P2, P3) spaced apart from one another in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). The first electrode member (1211) may include a first-1 electrode portion (12111) located in a first region (1201). The first electrode member (1211) may include a first-2 electrode portion (12112) located in a second region (1202). The first electrode member (1211) may include a first-third electrode portion (12113) located in a third region (1203). The first electrode member (1211) may include a first-fourth electrode portion (12114) located in a fourth region (1204). A first electrode tab (1220) may be formed on the first-first electrode portion (12111) of the first electrode member (1211).

[0131] Referring to FIGS. 3 and 4, the second electrode member (1212) may include a plurality of second electrode portions (12121, 12122, 12123, 12124). The plurality of second electrode portions (12121, 12122, 12123, 12124) may be separated from one another by a plurality of planes (P1, P2, P3) spaced apart from one another in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). The second electrode member (1212) may include a second-1 electrode portion (12121) located in a first region (1201). The second electrode member (1212) may include a second-2 electrode portion (12122) located in a second region (1202). The second electrode member (1212) may include a second-third electrode portion (12123) located in the third region (1203). The second electrode member (1212) may include a second-fourth electrode portion (12124) located in the fourth region (1204). A second electrode tab (1230) may be formed on the second-second electrode portion (12122) of the second electrode member (1212).

[0132] Referring to FIGS. 3 and 5, the third electrode member (1213) may include a plurality of third electrode portions (12131, 12132, 12133, 12134). The plurality of third electrode portions (12131, 12132, 12133, 12134) may be separated from one another by a plurality of planes (P1, P2, P3) spaced apart from one another in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). The third electrode member (1213) may include a third-1 electrode portion (12131) located in a first region (1201). The third electrode member (1213) may include a third-2 electrode portion (12132) located in a second region (1202). The third electrode member (1213) may include a third-third electrode portion (12133) located in the third region (1203). The third electrode member (1213) may include a third-fourth electrode portion (12134) located in the fourth region (1204). A third electrode tab (1240) may be formed on the third-third electrode portion (12133) of the third electrode member (1213).

[0133] Referring to FIGS. 3 and 5, the fourth electrode member (1214) may include a plurality of fourth electrode portions (12141, 12142, 12143, 12144). The plurality of fourth electrode portions (12141, 12142, 12143, 12144) may be separated from one another by a plurality of planes (P1, P2, P3) spaced apart from one another in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). The fourth electrode member (1214) may include a fourth-1 electrode portion (12141) located in a first region (1201). The fourth electrode member (1214) may include a fourth-2 electrode portion (12142) located in a second region (1202). The fourth electrode member (1214) may include a fourth-third electrode portion (12143) located in the third region (1203). The fourth electrode member (1214) may include a fourth-fourth electrode portion (12144) located in the fourth region (1204). A fourth electrode tab (1250) may be formed on the fourth-fourth electrode portion (12144) of the fourth electrode member (1214).

[0134] Referring to FIGS. 3, 4, and 5, a plurality of first electrode members (1211) and a plurality of third electrode members (1213) may be alternately stacked with a separator in between. The stack of the plurality of first electrode members (1211) and the plurality of third electrode members (1213) may form half of the electrode portion (1210) (e.g., a first stack portion (1205)).

[0135] Referring to FIGS. 3, 4, and 5, a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) may be alternately stacked with a separator in between. The stack of the plurality of second electrode members (1212) and the plurality of fourth electrode members (1214) may form the remaining half of the electrode portion (1210) (e.g., the second stack portion (1206)).

[0136] Referring to FIG. 3, a first stack portion (1205) comprising a plurality of first electrode members (1211) and a plurality of third electrode members (1213) and a second stack portion (1206) comprising a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) are connected in the width direction (e.g., +Y direction) of the electrode portion (1210). When forming the electrode assembly (1200), after stacking the plurality of first electrode members (1211) and the plurality of third electrode members (1213), the plurality of second electrode members (1212) and the plurality of fourth electrode members (1214) may be stacked.

[0137] Referring to FIG. 3, a plurality of first electrode tabs (1220) may overlap each other in a first region (1201) of an electrode assembly (1200). A plurality of second electrode tabs (1230) may overlap each other in a second region (1202) of an electrode assembly (1200). That is, a plurality of first electrode tabs (1220) may be grouped in the first region (1201), and a plurality of second electrode tabs (1230) may be grouped in the second region (1202). The plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) grouped together may be positioned spaced apart from each other in different regions (1201, 1202) of the electrode assembly (1200). A plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230), each grouped together, may be spaced apart in the width direction (e.g., +Y direction) and length direction (e.g., +X direction) of the electrode assembly (1200).

[0138] Referring to FIG. 6, the current collector (1300) may include a first current collector (1310), a second current collector (1320), and a connecting part (1330).

[0139] Referring to FIG. 6, the current collector (1300) may have a rectangular shape extending in the longitudinal direction of the electrode assembly (1200) (e.g., the +X direction in FIG. 3). The current collector (1300) may include a first current collector (1310), a connecting part (1330), and a second current collector (1320) arranged sequentially in the longitudinal direction of the rectangle. The connecting part (1330) may be positioned between the first current collector (1310) and the second current collector (1320). The first current collector (1310), the second current collector (1320), and the connecting part (1330) may be formed as a single unit. The first collector (1310) may be a part of the collector (1300) located on one side of the connecting part (1330), and the second collector (1320) may be a part of the collector (1300) located on the other side of the connecting part (1330).

[0140] Referring to FIGS. 2 and FIGS. 6, a first current collector (1310) may be welded to a plurality of first electrode tabs (1220). A plurality of first electrode tabs (1220) may be bent and welded onto the first current collector (1310). A second current collector (1320) is welded to a plurality of second electrode tabs (1230). A plurality of second electrode tabs (1230) may be bent and welded onto the second current collector (1320). The current collector (1300) may include a lower surface (1300a) facing the electrode assembly (1200). The lower surface (1300a) may be named the "first surface." The current collector (1300) may include an upper surface (1310a, 1320a) to which a plurality of first and second electrode tabs (1220, 1230) are welded. The upper surface (1310a, 1320a) may be named "second surface". The upper surface (1310a, 1320a) may be a surface opposite to the lower surface (1300a) facing the electrode assembly (1200). The upper surface (1310a, 1320a) may face the terminal (1420, 1420a). The upper surface (1310a, 1320a) may include a first welding surface (1310a) where a plurality of first electrode tabs (1220) are welded. The first welding surface (1310a) may be the upper surface of the first current collector (1310). The upper surface (1310a, 1320a) may include a second welding surface (1320a) where a plurality of second electrode tabs (1230) are welded. The second welding surface (1320a) may be the upper surface of the second current collector (1320).

[0141] Referring to FIGS. 2 and FIGS. 6, the connecting portion (1330) may be positioned between the first current collector (1310) and the second current collector (1320). Each of the first current collector (1310) and the second current collector (1320) may be connected to both sides of the connecting portion (1330). By separating the first current collector (1310) and the second current collector (1320) by the connecting portion (1330), the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) may not interfere with each other when each is welded.

[0142] Referring to FIGS. 2 and FIGS. 6, two current collectors (1300) may be provided, and the material of each current collector (1300) may be the same as the material of at least one of the first to fourth electrode tabs (1220, 1230, 1240, 1250). That is, the current collector (1300) may be formed of aluminum, copper, or nickel. The above description of the welding of the first and second electrode tabs (1220, 1230) and the current collector (1300) may be applied in the same way to the description of the welding of the third and fourth electrode tabs (1240, 1250) and the current collector (1300). For example, the third electrode tab (1240) can be welded to the first welding surface (1310a) of the first current collector (1310), and the fourth electrode tab (1250) can be welded to the second welding surface (1320a) of the second current collector (1320).

[0143] Referring to FIGS. 2 and FIGS. 6, the current collector (1300) may include a current collecting projection (1331). The current collecting projection (1330) may be electrically connected to an electrode terminal. The current collecting projection (1331) may be formed protruding from the connecting portion (1330). The current collecting projection (1331) may be positioned between the first current collecting portion (1310) and the second current collecting portion (1320). The material of the current collecting projection (1331) may be the same as or different from the material of the connecting portion (1330). For example, both the connecting portion (1330) and the current collecting projection (1331) may be formed of aluminum. Alternatively, the connecting portion (1330) may be formed of copper and the current collecting projection (1331) may be formed of aluminum. If the material of the current collecting projection (1331) and the material of the connecting part (1330) are the same, the connecting part (1330) and the current collecting projection (1331) can be formed integrally.

[0144] Referring to FIGS. 2 and FIGS. 6, the current collector (1300) may have a thickness of 0.5 to 3.0 mm. The width of the current collector (1300) may be 0.5 to 0.8 times the width of the electrode assembly (1200). The current collector (1300) is positioned on the electrode assembly (1200), and electrode tabs (1220, 1230, 1240, 1250) may be positioned on the upper surface (1310a, 1320a) of the current collector (1300) so that the electrode tabs (1220, 1230, 1240, 1250) can be welded on the upper surface (1310a, 1320a) of the current collector (1300). Conventionally, welding is performed after placing a current collector on top of an electrode tab, so it is necessary to melt down to the lower part of the current collector that is in contact with the electrode tab, and thus the thickness of the current collector cannot be increased. In a secondary battery (1000) according to one embodiment of the present invention, since the electrode tabs (1220, 1230, 1240, 1250) are welded on the upper surface (1310a, 1320a) of the current collector (1300), there is no need to melt down to the lower part of the current collector (1300) during the welding process, so the thickness of the current collector (1300) can be increased, and accordingly, the durability of the secondary battery can be improved. In addition, conventionally, welding is performed after placing a current collector on top of an electrode tab, so a high output of the laser is required to reach the electrode tab at the bottom of the current collector. However, according to one embodiment of the present invention, the secondary battery (1000) can be welded with a small output by welding the electrode tabs (1220, 1230, 1240, 1250) on the upper surface (1310a, 1320a) of the current collector (1300).

[0145] Referring to FIG. 2 and FIG. 6, a secondary battery (1000) according to one embodiment of the present invention can reduce damage to the separator by welding electrode tabs (1220, 1230, 1240, 1250) on the upper surface (1310a, 1320a) of a current collector (1300) that does not face the electrode assembly (1200), thereby preventing sparks or foreign substances generated during the welding process from penetrating into the electrode assembly (1200).

[0146] Referring to FIGS. 2 and FIGS. 7, a protective layer (1340) may be disposed on the lower portion of the current collector (1300). The protective layer (1340) may be disposed on the lower portion (1300a) of the current collector (1300). The protective layer (1340) may be an insulating plate or an insulating film. The protective layer (1340) may protect the current collector (1300), electrode tabs (1220, 1230, 1240, 1250), and electrode assembly (1200). For example, an electrode tab (1220, 1230, 1240, 1250) and a current collector (1300) are provided on one side of the protective layer (1340), and an electrode part of an electrode assembly (1200) (e.g., the electrode part (1210) of FIG. 3) is provided on the other side of the protective layer (1340), thereby insulating the electrode part (1210) and the current collector (1300), so that electrical interference between the electrode tab (1220, 1230, 1240, 1250), the current collector (1300), and the electrode part (1210) can be prevented.

[0148] FIG. 8 is a flowchart showing a method for manufacturing a secondary battery according to an embodiment of the present invention, FIG. 9 is a diagram showing a state in which a plurality of first electrode tabs and a plurality of second electrode tabs are each grouped in a secondary battery according to an embodiment of the present invention, FIG. 10 is a diagram showing a state in which a plurality of first electrode tabs and a plurality of second electrode tabs are each welded in a secondary battery according to an embodiment of the present invention, FIG. 11 is a diagram showing a state in which a current collector is placed between a plurality of first electrode tabs and a plurality of second electrode tabs in a secondary battery according to an embodiment of the present invention, FIG. 12 is a diagram showing a state in which a current collector and the first and second electrode tabs are welded in a secondary battery according to an embodiment of the present invention, and FIG. 13 is a diagram showing a state in which a cap assembly is coupled with an electrode assembly in a secondary battery according to an embodiment of the present invention.

[0149] The assembly method of the first electrode tab (1220), second electrode tab (1230), current collector (1300), and terminal (1420) described with reference to FIG. 8 to 13 can be similarly applied to the assembly method of the third electrode tab (1240), fourth electrode tab (1250), current collector (1300), and terminal (1420a) as shown in FIG. 2.

[0150] Referring to FIGS. 8 and 9, a method for manufacturing a secondary battery according to one embodiment of the present invention may include the step (S1100) of preparing an electrode assembly. The electrode assembly (1200) may include an electrode portion (1210), a plurality of first electrode tabs (1220), and a plurality of second electrode tabs (1230).

[0151] Referring to FIG. 9, a plurality of first electrode tabs (1220) may be placed in one area of ​​the electrode assembly (1200) (e.g., a first area (1201)). When a plurality of electrode members (e.g., a plurality of first electrode members (1211) of FIG. 3) are stacked to form a first stack portion (1205), the plurality of first electrode tabs (1220) may be positioned so as to overlap each other in the first electrode tab area (1201). That is, the plurality of first electrode tabs (1220) may be grouped in the first area (1201).

[0152] Referring to FIG. 9, a plurality of second electrode tabs (1230) may be placed in one area (e.g., a second area (1202)) of the electrode assembly (1200). When a plurality of electrode members (e.g., a plurality of second electrode members (1212) of FIG. 3) are stacked to form a second stack portion (1206), the plurality of second electrode tabs (1230) may be positioned so as to overlap each other in the second electrode member area (1202). That is, the plurality of second electrode tabs (1230) may be grouped in the second area (1202).

[0153] Referring to FIGS. 4, 5, and 9, only one electrode tab (1220, 1230, 1240, 1250) is formed in one electrode member (1211, 1212, 1213, 1214), but in a secondary battery (1000) according to one embodiment of the present invention, by making the positions where the electrode tabs (1220, 1230, 1240, 1250) are formed in each electrode member (1211, 1212, 1213, 1214) different, two groups of electrode tabs with different positions may be formed in the positive and negative electrodes, respectively, after the electrode members (1211, 1212, 1213, 1214) are stacked. In another embodiment, two or more electrode tabs with different positions may be formed in the same electrode.

[0154] Referring to FIG. 9, a plurality of grouped first electrode tabs (1220) may be located in a first region (1201) of the first electrode tab stack portion (1205). A plurality of grouped second electrode tabs (1230) may be located in a second region (1202) of the second stack portion (1206). The plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) may be spaced apart from each other in the longitudinal direction (e.g., +X direction) of the electrode assembly (1200). A gap (G) may be formed between the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230). The electrode assembly (1200) may include a bridge portion (1207) formed between the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230). The bridge portion (1207) may be a part of an electrode assembly (1200) located between a first electrode tab (1220) and a second electrode tab (1230) spaced apart in the longitudinal direction (e.g., +X direction). The bridge portion (1207) may provide a location where a current collecting projection (e.g., current collecting projection (1331) of FIG. 6) of a current collector (e.g., current collecting collector (1300) of FIG. 6) protrudes. A connection portion (e.g., connection portion (1330) of FIG. 6) of a current collector (e.g., current collecting collector (1300) of FIG. 6) may be positioned to correspond to the bridge portion (1207). A current collecting projection (e.g., current collecting projection (1331) of FIG. 6) of the current collector (1300) may protrude toward a terminal (e.g., terminal (1420) of FIG. 2) at a location corresponding to the bridge portion (1207).

[0155] Referring to FIG. 8 and FIG. 10, a method for manufacturing a secondary battery according to one embodiment of the present invention may include a step of primary welding (S1200). A plurality of grouped first electrode tabs (1220) may be primary welded to each other, and a plurality of second electrode tabs (1230) may be primary welded to each other.

[0156] Referring to FIG. 10, a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) may be electrode tabs of the same polarity, and in order to stably weld a large number of first electrode tabs and second electrode tabs (1220, 1230), a plurality of first electrode tabs may be welded together and a plurality of second electrode tabs may be welded together, and then a second welding may be performed on a current collector (e.g., the current collector (1300) of FIG. 11). A plurality of third electrode tabs (e.g., the third electrode tab (1240) of FIG. 3) and a plurality of fourth electrode tabs (e.g., the fourth electrode tab (1250) of FIG. 3) may be electrode tabs of the same polarity, and, in the same case as the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230), after the plurality of third electrode tabs are welded together and the plurality of fourth electrode tabs are welded together, they may be welded secondarily on the current collector (1300). The plurality of electrode tabs (1220, 1230, 1240, 1250) that overlap at each position may each be welded first by ultrasonic welding, laser welding, etc., to facilitate the movement of current.

[0157] Referring to FIG. 10, the electrode assembly (1200) may include a first electrode tab assembly (1221). The first electrode tab assembly (1221) may be a structure in which a plurality of first electrode tabs (1220) are welded together. That is, the first electrode tab assembly (1221) may be an assembly in which a plurality of first electrode tabs (1220) that overlap each other are welded together.

[0158] Referring to FIG. 10, the first electrode tab assembly (1221) may include a first-1 assembly portion (1221a). The first-1 assembly portion (1221a) may be a portion where a plurality of first electrode tabs (1220) are welded together in an overlapping state. The first electrode tab assembly (1221) may include a first assembly weld portion (1221d). The first assembly weld portion (1221d) may be formed on the first-1 assembly portion (1221a). The first electrode tab assembly (1221) may include a first-2 assembly portion (1221b) and a first-3 assembly portion (1221c). The first-2 assembly portion (1221b) may be a portion extending in one direction (e.g., +Y direction) from the first-1 assembly portion (1221a), and the first-3 assembly portion (1221c) may be a portion extending in the opposite direction (e.g., -Y direction) from the first-1 assembly portion (1221a) to the first-2 assembly (1221b). The first-3 assembly portion (1221c) may be extended in a direction facing the outside of the electrode assembly (1200), that is, in a direction opposite to the direction facing the second stack portion (1206) with respect to the width direction of the electrode assembly (1200).

[0159] Referring to FIG. 10, the electrode assembly (1200) may include a second electrode tab assembly (1231). The second electrode tab assembly (1231) may be a structure in which a plurality of second electrode tabs (1230) are welded together. That is, the second electrode tab assembly (1231) may be an assembly in which a plurality of second electrode tabs (1230) that overlap each other are welded together.

[0160] Referring to FIG. 10, the second electrode tab assembly (1231) may include a second-1 assembly portion (1231a). The second-1 assembly portion (1231a) may be a portion where a plurality of second electrode tabs (1230) are welded together in an overlapping state. The second electrode tab assembly (1231) may include a second assembly weld portion (1231d). The second assembly weld portion (1231d) may be formed on the second-1 assembly portion (1231a). The second electrode tab assembly (1231) may include a second-2 assembly portion (1231b) and a second-3 assembly portion (1231c). The second-2 assembly portion (1231b) may be a portion extending in one direction (e.g., -Y direction) from the second-1 assembly portion (1231a), and the second-3 assembly portion (1231c) may be a portion extending in the opposite direction (e.g., +Y direction) from the second-1 assembly portion (1231a) to the second-2 assembly (1231b). The second-3 assembly portion (1231c) may be extended in a direction facing the outside of the electrode assembly (1200), that is, in a direction opposite to the direction facing the first stack portion (1205) with respect to the width direction of the electrode assembly (1200).

[0161] Referring to FIG. 8 and FIG. 11, a method for manufacturing a secondary battery according to one embodiment of the present invention may include a step (S1300) of placing a current collector (1300). A current collector (1300) may be placed between a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) that have been welded in the first stage. In order to connect the plurality of electrode tabs (1220, 1230) to the current collector (1300), in this embodiment, electrode tabs (1220, 1230) of the same polarity are divided into two electrode tab assemblies (1221, 1231) and welded to the current collector (1300). For example, the first electrode tab assembly (1221) can be welded to the first current collector (e.g., the first current collector (1310) of FIG. 12) of the current collector (1300), and the second electrode tab assembly (1231) can be welded to the second current collector (e.g., the second current collector (1320) of FIG. 12) of the current collector (1300).

[0163] Referring to FIG. 11, the current collector (1300) may be positioned to cover at least a portion of the first electrode tab assembly (1221) and at least a portion of the second electrode tab assembly (1231). The current collector (1300) may overlap with each of at least a portion of the first electrode tab assembly (1221) and at least a portion of the second electrode tab assembly (1231) in a third direction (e.g., +Z direction). For example, the current collector (1300) may be positioned to cover the first-2 assembly portion (1221b) and the second-2 assembly portion (1231b). The first-2 assembly portion (1221b) may be located between the electrode portion (1210) of the electrode assembly (1200) and the current collector (1300). The second-2 assembly portion (1231b) may be located between the electrode portion (1210) of the electrode assembly (1200) and the current collector (1300). The current collector projection (1331) may protrude between the first-2 assembly portion (1221b) and the second-2 assembly portion (1231b). The current collector (1300) may be placed in the space formed between the first electrode tab assembly (1221) and the second electrode tab assembly (1231). To facilitate the placement of the current collector (1300), each of the first electrode tab assembly (1221) and the second electrode tab assembly (1231) may be temporarily bent toward the outer side of the electrode assembly (1200).

[0164] Referring to FIGS. 8, 11, and 12, a method for manufacturing a secondary battery according to one embodiment of the present invention may include a step (S1400) of bending a first electrode tab (1220) and a second electrode tab (1230) toward the upper surface (1310a, 1320a) of a current collector (1300), respectively. A plurality of first electrode tabs (1220) may be bent toward the upper surface (1310a) of the first current collector (1310) of the current collector (1300), and a plurality of second electrode tabs (1230) may be bent toward the upper surface (1320a) of the second current collector (1320) of the current collector (1300). A plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) may be bent in opposite directions.

[0165] Referring to FIGS. 8, 11, and 12, the first electrode tab assembly (1221) can be bent onto the first welding surface (1310a) of the first current collector (1310). The first-1 assembly part (1221a) can be bent onto the first welding surface (1310a). The first-1 assembly part (1221a) can be bent toward the second stack part (e.g., the second stack part (1206) of FIG. 3). At this time, the first-2 assembly part (1221b) is positioned between the lower surface (1300a) of the current collector (1300) and the electrode part (1210) of the electrode assembly (1200), so that the bending of the first-1 assembly part (1221a) can be supported by the first-2 assembly part (1221b) pressed by the current collector (1300). The first-3 assembly portion (1221c) can provide structural stability to the first electrode tab assembly (1221) by extending away from the first-1 assembly portion (1221a) in a direction away from the current collector (1300). For example, the first-3 assembly portion (1221c) can distribute the stress in the width direction applied to the first-1 assembly portion (1221a) by having a structure that spreads widely in the width direction (e.g., -Y direction) of the first-1 assembly portion (1221a) during the bending and welding process of the first-1 assembly portion (1221a).

[0166] Referring to FIGS. 8, 11, and 12, the second electrode tab assembly (1231) can be bent onto the second welding surface (1320a) of the second current collector (1320). The second-1 assembly part (1231a) can be bent onto the second welding surface (1320a). The second-1 assembly part (1231a) can be bent toward the first stack part (e.g., the first stack part (1205) of FIG. 3). At this time, the second-2 assembly part (1231b) is positioned between the lower surface (1300a) of the current collector (1300) and the electrode part (1210) of the electrode assembly (1200), so that the bending of the second-1 assembly part (1231a) can be supported by the second-2 assembly part (1231b) pressed by the current collector (1300). The second-third assembly portion (1231c) can provide structural stability to the second electrode tab assembly (1231) by extending away from the second-first assembly portion (1231a) and the current collector (1300). For example, the second-third assembly portion (1231c) can distribute the stress in the width direction applied to the second-first assembly portion (1231a) by having a structure that spreads widely in the width direction (e.g., +Y direction) of the second-first assembly portion (1231a) during the bending and welding process of the second-first assembly portion (1231a).

[0167] Meanwhile, the sum of the areas of the first-1 assembly part (1221a) and the second-1 assembly part (1231a) that are bent and placed on the current collector (1300) may have a predetermined ratio relative to the area of ​​the upper surface of the contact plate (1300). For example, the sum of the areas of the first-1 assembly part (1221a) and the second-1 assembly part (1231a) may be 1 / 4 to 1 / 6 of the area of ​​the upper surface of the contact plate (1300).

[0168] If the area of ​​the electrode tab placed on the current collector is small, it is difficult for the electrode tab to be sufficiently bonded to the current collector, and the current flow may not be smooth. Therefore, it is desirable that the area of ​​the electrode tab placed on the upper surface of the current collector be at least 1 / 6 of the area of ​​the current collector.

[0169] In addition, if many electrode tabs are placed on the current collector, the amount of melted electrode tabs increases during the secondary welding process, which can result in uneven weld bead height. This can cause problems when assembling the cap plate. Therefore, it is desirable that the area of ​​the electrode tabs be less than 1 / 4 of the area of ​​the current collector.

[0170] Referring to FIGS. 11 and 12, the first-2 assembly part (1221b) may be located between the first current collector weld part (1221e) and the electrode assembly (1200). The second-2 assembly part (1231b) may be located between the second current collector weld part (1231e) and the electrode assembly (1200). The first current collector part (1310) may be located between the first current collector weld part (1221e) and the first-2 assembly part (1221b). The second current collector part (1320) may be located between the second current collector weld part (1231e) and the second-2 assembly part (1231b). Due to the above-described structure, foreign substances generated when welding the first-1 and second-1 assembly parts (1221a, 1231a) to the current collector (1300) may be blocked by the first-2 and second-2 assembly parts (1221b, 1231b) and may not be directed toward the electrode assembly (1200).

[0171] Referring to FIGS. 8 and 12, a method for manufacturing a secondary battery according to one embodiment of the present invention may include a step (S1500) of welding a current collector (1300) and electrode tabs (1220, 1230). A plurality of first electrode tabs (1220) may be welded to a first current collector (1310), and a plurality of second electrode tabs (1230) may be welded to a second current collector (1320). Welding may be performed downward from an upper position of the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230). Welding may be performed using methods such as ultrasonic welding or laser welding.

[0172] When welding, welding can proceed from a plurality of first electrode tabs (1220) toward the first current collection part (1310) side at the first current collection part (1300) of the current collector (1300), and from a plurality of second electrode tabs (1230) toward the second current collection part (1320) side at the second current collection part (1320) of the current collector (1300).

[0173] Referring to FIG. 12, the first electrode tab assembly (1221) may be welded to the first current collector (1310), and the second electrode tab assembly (1231) may be welded to the second current collector (1320). The first electrode tab assembly (1221) may include a first current collector weld portion (1221e). The first current collector weld portion (1221e) may be formed in the first-1 assembly portion (1221a). The first current collector weld portion (1221e) may be formed by welding the first electrode tab assembly (1221) and the current collector (1300). The second electrode tab assembly (1231) may include a second current collector weld portion (1231e). The second current collector weld portion (1231e) may be formed in the second-1 assembly portion (1231a). The second current collector weld portion (1231e) can be formed by welding the second electrode tab assembly (1231) and the current collector (1300).

[0174] Referring to FIGS. 11 and 12, after forming first and second electrode tab assemblies (1221, 1231) by first welding a plurality of electrode tabs (1220, 1230), the first and second electrode tab assemblies (1221, 1231) can be secondarily welded to a current collector (1300). Accordingly, the first and second electrode tab assemblies (1221, 1231) may include first and second assembly weld portions (1221d, 1231d) and first and second current collector weld portions (1221e, 1231e). By welding a plurality of electrode tabs (1220, 1230) in the manner described above, all of the plurality of electrode tabs (1220, 1230) can be stably welded to the current collector (1300) so that there are no unwelded electrode tabs among the plurality of electrode tabs (1220, 1230). The primary welding direction and the secondary welding direction of the first and second electrode tab assemblies (1221, 1231) may be different. For example, the welding portions of the first and second assemblies (1221d, 1231d) may be formed in a first direction (e.g., +X direction), and the welding portions of the first and second current collectors (1221e, 1231e) may be formed in a second direction (e.g., +Y direction). As described above, since the first welding direction and the second welding direction are different, damage to the first and second electrode tab assemblies (1221, 1231) that may occur due to welding being performed repeatedly at the same location can be prevented. The first and second assembly welding portions (1221d, 1231d) may extend across the first and second electrode tab assemblies (1221, 1231) in the longitudinal direction (e.g., +X direction). Multiple first and second current collector welding portions (1221e, 1231e) may be formed spaced apart from each other in the longitudinal direction (e.g., +X direction) of the first and second electrode tab assemblies (1221, 1231).In a secondary battery (1000) according to one embodiment of the present invention, the assembly weld portion (1221d, 1231d) formed by the first welding and the current collector weld portion (1221e, 1231e) formed by the second welding can be distinguished from each other. For example, the assembly weld portion (1221d, 1231d) formed by the first welding and the current collector weld portion (1221e, 1231e) formed by the second welding can be formed in directions that intersect each other. The assembly weld portion (1221d, 1231d) formed by the first welding and the current collector weld portion (1221e, 1231e) formed by the second welding may be formed without directionality in different regions of the electrode tab assembly (1221, 1231).

[0175] Meanwhile, the area of ​​the secondary welding region formed on the first and second electrode tabs may have a predetermined ratio to the area of ​​the first and second electrode tabs (1221a, 1231a) bent and placed on the current collector. For example, the area of ​​each secondary welding region formed on the first and second electrode tabs may be 1 / 5 to 1 / 7 of the area of ​​each of the first and second electrode tabs (1221a, 1231a) bent and placed on the current collector.

[0176] If the secondary welding area is narrow, the electrical resistance increases, which may increase the amount of heat generated in the first and second electrode tabs. In addition, the welding joint strength may weaken, causing the electrode tabs and the current collector to separate. Therefore, it is desirable that the area of ​​the secondary welding area be at least 1 / 7 of the area of ​​the current collector.

[0177] If the area of ​​the secondary welding region is large, electrical resistance may decrease and current flow between the electrode tab and the external circuit may be improved. However, if the secondary welding region is too large, the effect of improved current flow may be offset by the increased welding time, potentially leading to a decrease in manufacturing efficiency. Additionally, if the secondary welding region is large, heat may be transferred to the outside of the current collector during the welding process, potentially damaging the separator. Therefore, it is desirable that the area of ​​the secondary welding region be 1 / 5 or less of the current collector area.

[0178] In this embodiment, a plurality of electrode tabs are welded to a current collector (1300) after first welding the first electrode tabs (1220) to each other and the second electrode tabs (1230) to each other. However, in other embodiments, the plurality of electrode tabs (1220, 1230) may be welded directly onto the current collector (1300) by bending them without first welding. For example, a secondary battery according to another embodiment of the present invention may weld each of the plurality of electrode tabs (1220, 1230) to the current collector (1300). That is, a secondary battery according to another embodiment of the present invention may weld the plurality of electrode tabs (1220, 1230) to the current collector (1300) after each of the plurality of electrode tabs (1220, 1230) is bent toward the surface of the current collector (1300) and stacked on top of each other.

[0179] Referring to FIG. 12, a current collecting projection (1331) may be positioned between the first electrode tab assembly (1221) and the second electrode tab assembly (1231). The current collecting projection (1331) may be positioned between the first-1 assembly portion (1221a) and the second-1 assembly portion (1231a). The current collecting projection (1331) may be positioned between the first current collector welding portion (1221e) and the second current collector welding portion (1231e).

[0180] Meanwhile, after the completion of the second welding, a cover member (1360) may be placed on the welded portion of the current collector (1300). The cover member (1360) may cover at least a portion of the electrode assembly (1200). The cover member (1360) may include an insulating material. The connection portion (1330) and the current collection projection (1331) may be exposed on the outside of the cover member (1360). The terminal (1420, 1420a) may be coupled with the current collection projection (1331) exposed on the outside of the cover member (1360). The width (w1) of the cover member (1360) may be 1 to 1.2 times the width (w2) of the first and second electrode tabs. By forming the width (w1) of the cover member (1360) to be 1 to 1.2 times the width (w2) of the first and second electrode tabs, the entire welded portion can be covered while minimizing the area fixed by the cover member (1360).

[0181] Referring to FIGS. 2 and FIGS. 13, the electrode assembly (1200) with the current collector (1300) welded thereto can be accommodated in a case (1100), and the cap assembly (1400) can seal the opening of the case (1100). At this time, after the current collector projection (1331) is inserted into the through hole of the terminal (1420) of the cap assembly (1400), the outer surface of the end of the current collector projection (1331) and the inner surface of the end of the through hole can be welded together.

[0182] FIG. 14 is a block diagram illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. FIG. 15 to 20 are drawings illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. The description of a method for manufacturing a secondary battery according to one embodiment of the present invention described with reference to FIG. 1 to 13 can be equally applied to a method for manufacturing a secondary battery according to another embodiment of the present invention described with reference to FIG. 14 to 20.

[0183] Referring to FIGS. 14 to 20, a method for manufacturing a secondary battery may include a step (S2100) of preparing an electrode assembly (1200). A method for manufacturing a secondary battery may include a step (S2200) of welding a plurality of first electrode tabs (1220) together and welding a plurality of second electrode tabs (1230) together. A method for manufacturing a secondary battery may include a step (S2300) of placing an insulating member (1350). A method for manufacturing a secondary battery may include a step (S2400) of placing a current collector (2300) between a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230). A method for manufacturing a secondary battery may include a step (S2500) of bending a plurality of first electrode tabs (1220) toward a first current collector (2310) and bending a plurality of second electrode tabs (1230) toward a second current collector (2320). A method for manufacturing a secondary battery may include a step (S2600) of welding a plurality of first electrode tabs (1220) and a first current collector (2310) and welding a plurality of second electrode tabs (1230) and a second current collector (2320). A method for manufacturing a secondary battery may include a step (S2700) of placing a cover member (1360).

[0185] Referring to FIGS. 9, 10, and 14, a method for manufacturing a secondary battery may include the step of preparing an electrode assembly (1200) (S2100) and the step of welding a plurality of first electrode tabs (1220) together and welding a plurality of second electrode tabs (1230) together (S2200). The description for each step (S2100, S2200) may be applied in the same way as the description with reference to FIGS. 9 and 10. For example, a plurality of first electrode tabs (1220) may be welded together to form a first electrode tab assembly (1221) including a first assembly welded portion (1221d), and a plurality of second electrode tabs (1230) may be welded together to form a second electrode tab assembly (1231) including a second assembly welded portion (1231d).

[0186] Referring to FIGS. 15 and 16, an insulating member (1350) may be disposed. The insulating member (1350) may be disposed to cover at least a portion of the electrode assembly (1200). At least a portion of the insulating member (1350) may be bent. The electrode portion (1210) may include a first electrode surface (1210a) and a second electrode surface (1210b). First and second electrode tab assemblies (1221, 1231) may be disposed on the first electrode surface (1210a). The second electrode surface (1210b) may extend in a direction intersecting the first electrode surface (1210a). The insulating member (1350) may include a first insulating portion (1351) and a second insulating portion (1352). The first insulating portion (1351) may cover the first electrode surface (1210a). The second insulating portion (1352) may cover the second electrode surface (1210b). The insulating member (1350) may include a first insulating member (1350a) extending toward the first electrode tab assembly (1221) and a second insulating member (1350b) extending toward the second electrode tab assembly (1231). The insulating member (1350) may cover at least a portion of the first and second electrode tab assemblies (1221, 1231). For example, the first insulating member (1350a) may cover at least a portion of the first-2 assembly portion (1221b), and the second insulating member (1350b) may cover at least a portion of the second-2 assembly portion (1231b). The first electrode tab assembly (1221) may include a first assembly insulating portion (1221b1) covered by the insulating member (1350). The second electrode tab assembly (1231) may include a second assembly insulating portion (1231b1) covered by an insulating member (1350).

[0187] Referring to FIGS. 17 and 18, a current collector (2300) may be disposed on an electrode assembly (1200), and first and second electrode tab assemblies (1221, 1231) may be welded to the current collector (2300). The structure in which the first and second electrode tab assemblies (1221, 1231) are welded to the current collector (2300) may be described in the same way as the description of the weld structure described with reference to FIGS. 11 and 12.

[0188] Referring to FIGS. 17 and 18, a current collector (2300) may be disposed on an electrode assembly (1200). The current collector (2300) may extend across each of the first electrode tab assembly (1221) and the second electrode tab assembly (1231). The current collector (2300) may include a first current collector (2310) welded to the first electrode tab assembly (1221) and a second current collector (2320) welded to the second electrode tab assembly (1231). The current collector (2300) may include a connecting portion (2330) located between the first current collector (2310) and the second current collector (2320). The current collector (2300) may include a current collector edge (2311). The current collector edge (2311) may be disposed on one side of the first current collector (2310). A current collecting edge (2311) may be positioned between the edge (1200d) of the electrode assembly (1200) and the first and second electrode tab assemblies (1221, 1231). The current collector (2300) may include a current collecting projection (2331). The current collecting projection (2331) may protrude from the current collecting edge (2311). The current collecting projection (2331) may be positioned between the edge (1200d) of the electrode assembly (1200) and the first and second electrode tab assemblies (1221, 1231).

[0189] Referring to FIGS. 17 and 18, the first electrode tab assembly (1221) can be bent toward the first current collector (2310), and the first electrode tab assembly (1221) can be welded to the first welding surface (2310a) of the first current collector (2310). The second electrode tab assembly (1231) can be bent toward the second current collector (2320), and the second electrode tab assembly (1231) can be welded to the second welding surface (2320a) of the second current collector (2320). The current collector (2300) may include an upper surface (2300b) comprising the first welding surface (2310a) and the second welding surface (2320a). The first and second electrode tab assemblies (1221, 1231) can be welded to the upper surface (2300b) of the current collector (2300).

[0190] Referring to FIGS. 17 and 18, the ends of the first and second electrode tab assemblies (1221, 1231) may be spaced apart from one side (2300c) of the adjacent current collector (2300). For example, after the first and second electrode tab assemblies (1221, 1231) are welded to the current collector (2300), the ends of the first-1 and second-1 assembly parts (1221a, 1231a) may be spaced apart from one side (2300c) of the adjacent current collector (2300). The end of the first-1 assembly part (1221a) may be spaced apart by a first gap (d5) from one side (2300c) of the adjacent current collector (2300). The end of the second-1 assembly part (1231a) may be spaced apart by a second gap (d6) from one side (2300c) of the adjacent current collector (2300).

[0191] Referring to FIGS. 17 and 18, insulating members (1350a, 1350b) may be placed between the electrode portion (1210) and the current collector (2300). For example, at least a portion of the first insulating member (1350a) may be placed between the electrode portion (1210) and the first current collector (2310). For example, at least a portion of the second insulating member (1350b) may be placed between the electrode portion (1200) and the second current collector (2320). Because the insulating members (1350a, 1350b) are placed between the electrode portion (1210) and the current collector (2300), the flow of foreign matter into the electrode portion (1210) that occurs when the first and second electrode tab assemblies (1221, 1231) are welded to the current collector (2300) may be blocked. In addition, due to the arrangement of the insulating members (1350a, 1350b), electrical insulation can be achieved between the electrode tab assembly (1221, 1231) and the current collector (2300) welded to the assembly and the electrode part (1210).

[0192] Referring to FIGS. 19 and 20, a cover member (1360) may be disposed. The cover member (1360) may cover an electrode tab assembly (e.g., electrode tab assembly (1221, 1231) of FIG. 18) and a current collector (e.g., current collector (2300) of FIG. 18). The cover member (1360) may cover at least a portion of the electrode assembly (1200). The cover member (1360) may include an insulating material. A current collecting edge (2311) and a current collecting projection (2331) may be exposed on the outside of the cover member (1360). A terminal (e.g., terminal (1420, 1420a) of FIG. 1) may be coupled with a current collecting projection (2331) exposed on the outside of the cover member (1360).

[0193] Referring to FIGS. 19 and 20, a cover member (1360) can cover an electrode portion (1210), an insulating member (1350), a current collector (2300), and an electrode tab assembly (1221). The cover member (1360) can be stacked with each of the electrode portion (1210), the insulating member (1350), the current collector (2300), and the electrode tab assembly (1221). For example, the electrode portion (1210), the insulating member (1350), the current collector (2300), the electrode tab assembly (1221), and the cover member (1360) can be stacked in order along one direction (e.g., the +Z direction). At least a portion of the electrode tab assembly (1221) (e.g., a first-second assembly portion (1221b)) can be placed between the electrode portion (1210) and the insulating member (1350). On a virtual line (L1) extended in one direction (e.g., +Z direction), an electrode portion (1210), a first-second assembly portion (1221b), an insulating member (1350), a current collector (2300), a first-first assembly portion (1221a), and a cover member (1360) can be stacked in order. Due to the structure described above, the first-first assembly portion (1221a) is bent while the first-second assembly portion (1221b) is pressed toward the electrode portion (1210) by the insulating member (1350) and the current collector (2300), so the bending of the first-first assembly portion (1221a) can be made easier. Due to the above-described structure, when welding the first-1 assembly part (1221a) to the current collector (2300), the insulating member (1350) and the first-2 assembly part (1221b) are positioned between the current collector (2300) and the electrode part (1210), so that foreign substances generated by welding can be prevented from flowing toward the electrode part (1210).

[0195] In a secondary battery according to a comparative example, the current collector must be thin to transfer heat to the electrode tab located below because the current collector is welded at the top of the electrode tab, which leads to reduced durability. However, in a secondary battery according to one embodiment of the present invention, the thickness of the current collector can be secured by bending and welding a plurality of electrode tabs on the current collector, and the electrode tabs can be welded to the current collector more efficiently.

[0196] In addition, the present invention allows for stable welding of electrode tabs without any unwelded parts by dividing a plurality of electrode tabs with the same polarity into two groups and welding them.

[0198] Although an embodiment of the present invention has been described above, those skilled in the art may modify and change the present invention in various ways by adding, changing, deleting, or adding components, etc., without departing from the spirit of the present invention as described in the claims, and such modifications and changes are also to be included within the scope of the rights of the present invention. Explanation of the symbols

[0199] 1000 : Secondary battery 1100 : Case 1200 : Electrode assembly 1220, 1230, 1240, 1250 : Electrode tabs 1300 : Current collector 1310: 1st Censorate 1320: 2nd Censorate 1330 : Connecting part 1331 : Current collector projection 1400: Cap Assembly 1410: Cap Plate 1420, 1420a: Terminal 1411: Vent hole 1412: Electrolyte inlet

Claims

Claim 1 A secondary battery comprising: an electrode assembly having a plurality of first electrode members having a plurality of first electrode members having a plurality of first electrode tabs formed at a first position and a plurality of second electrode members having a plurality of second electrode tabs formed at a second position; a plurality of first electrode tabs formed at a first position at one end of the electrode assembly and a plurality of second electrode tabs formed at a second position at one end of the electrode assembly; and a current collector having a first current collector welded to the plurality of first electrode tabs and a second current collector welded to the plurality of second electrode tabs, wherein the first electrode members and the second electrode members have the same polarity, the plurality of first electrode tabs and the plurality of second electrode tabs are spaced apart in the width direction (y direction) and length direction (x direction) of the electrode assembly, the plurality of first electrode tabs are bent in one direction toward the first current collector of the current collector, and the plurality of second electrode tabs are bent in the opposite direction to the first electrode tabs toward the second current collector of the current collector. Claim 2 A secondary battery according to claim 1, wherein the current collector comprises a first surface facing the electrode portion and a second surface opposite to the first surface, at least a portion of which is located between the first electrode tab and the second electrode tab, and the first electrode tab and the second electrode tab are positioned at offset positions with respect to each other with the current collector in between, and are each bent toward the second surface and welded to the second surface. Claim 3 delete Claim 4 delete Claim 5 A secondary battery according to claim 1, wherein the plurality of first electrode tabs are pre-welded to each other and the plurality of second electrode tabs are pre-welded to each other. Claim 6 A secondary battery according to claim 1, wherein the first current collector and the second current collector in the above current collector are arranged in the longitudinal direction of the electrode assembly. Claim 7 A secondary battery according to claim 1, wherein the current collector further comprises a connecting portion disposed between the first current collector and the second current collector and having a current collecting projection. Claim 8 A secondary battery according to claim 1, wherein the current collector further comprises a current collecting edge having a current collecting projection disposed on one side of the first current collecting part. Claim 9 A secondary battery according to claim 1, wherein a protective layer is disposed on the lower part of the current collector. Claim 10 A secondary battery according to claim 1, wherein the thickness of the current collector is 0.5 to 3.0 mm. Claim 11 A secondary battery according to claim 2, further comprising a cover member covering the first and second electrode tabs each welded to the current collector. Claim 12 In claim 7, the current collecting protrusion is formed of the same material as the first current collecting part and the second current collecting part, in a secondary battery. Claim 13 In claim 7, the current collecting protrusion is formed of a material different from the first current collecting part and the second current collecting part, in a secondary battery. Claim 14 A plurality of first electrode members, each comprising a first electrode tab; a plurality of second electrode members, each comprising a second electrode tab; a plurality of third electrode members, each comprising a third electrode tab; a plurality of fourth electrode members, each comprising a fourth electrode tab; an electrode assembly having a length in a first direction and a width in a second direction perpendicular to the first direction, comprising a first stack portion formed by stacking the plurality of first electrode members and the plurality of third electrode members, and a second stack portion formed by stacking the plurality of second electrode members and the plurality of fourth electrode members, and stacked in the first stack portion and the second direction; a first electrode tab assembly formed by combining the first electrode tab of each of the plurality of first electrode members to the first stack portion, and located in a first region among a plurality of regions of the electrode assembly separated in the first direction. A secondary battery comprising a second electrode tab assembly formed by combining the second electrode tabs of each of the plurality of second electrode members and a second electrode tab assembly located in a second region different from the first region among the plurality of regions of the electrode assembly separated in the first direction, wherein the first electrode member and the second electrode member have the same polarity, and the first electrode tab assembly and the second electrode tab assembly are spaced apart in the width direction (y direction) and length direction (x direction) of the electrode assembly. Claim 15 A secondary battery according to claim 7, further comprising: a case having one end open and accommodating the electrode assembly; and a cap assembly coupled to one end of the case and having an electrode terminal electrically connected to the current collector. Claim 16 A secondary battery according to claim 15, wherein the electrode terminal is provided with a through hole, and the current collecting projection is inserted into the through hole of the electrode terminal. Claim 17 A preparation step in which an electrode assembly is prepared, comprising a plurality of first electrode members having a plurality of first electrode members having a plurality of first electrode tabs formed at a first position and a plurality of second electrode members having a plurality of second electrode tabs formed at a second position, and a plurality of first electrode tabs formed at a first position at one end of the electrode member and a plurality of second electrode tabs formed at a second position at one end of the electrode member; a first welding step in which the plurality of first electrode tabs and the plurality of second electrode tabs are spaced apart in the width direction (y direction) and the length direction (x direction) of the electrode assembly, and the plurality of first electrode tabs are welded to each other and the plurality of second electrode tabs are welded to each other; a current collector placement step in which a current collector is placed between the plurality of first electrode tabs and the plurality of second electrode tabs that have been welded in the first welding step; and a bending step in which the plurality of first electrode tabs are bent toward the upper surface of the first current collector portion of the current collector and the plurality of second electrode tabs are bent toward the upper surface of the second current collector portion of the current collector. A method for manufacturing a secondary battery, comprising: a secondary welding step in which a plurality of first electrode tabs are each welded to a first current collector and a plurality of second electrode tabs are each welded to a second current collector; wherein the plurality of first electrode tabs and the plurality of second electrode tabs have the same polarity. Claim 18 delete Claim 19 A method for manufacturing a secondary battery according to claim 17, wherein the first current collector and the second current collector in the above current collector are arranged in the longitudinal direction of the electrode assembly. Claim 20 A method for manufacturing a secondary battery according to claim 17, wherein a protective layer is disposed on the lower part of the above-mentioned current collector. Claim 21 A method for manufacturing a secondary battery according to claim 17, wherein the current collector comprises a current collecting projection formed of a material different from the first current collecting portion and the second current collecting portion between the first current collecting portion and the second current collecting portion. Claim 22 A method for manufacturing a secondary battery according to claim 17, wherein the current collector has a current collecting projection formed of the same material as the first current collecting portion and the second current collecting portion between the first current collecting portion and the second current collecting portion.

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