Secondary battery and method for manufacturing same

Abstract

The present disclosure relates to a current collector, a secondary battery including the same and a manufacturing method thereof. The current collector according to the present disclosure includes a first current collecting portion, a second current collecting portion, and a connection portion. The first current collecting portion may be welded to a plurality of first electrode tabs. The second current collecting portion may be electrically connected to the first current collecting portion, and may be welded to a plurality of second electrode tabs. The connection portion may have one end to which the first current collecting portion is connected and the other end to which the second current collecting portion is connected, and may include a current collecting protrusion. The current collecting protrusion may be made of a different material from the connection portion.

Description

Secondary battery and its manufacturing method

[0001] The present invention relates to a secondary battery and a method for manufacturing the same.

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

[0003] Secondary batteries can be manufactured in various forms depending on the shape of the battery case, and can be classified, for example, into can-type secondary batteries in which the electrode assembly is built into a metal can, and pouch-type secondary batteries in which the electrode assembly is built into a pouch made of an aluminum laminate sheet. Can-type secondary batteries can be classified into cylindrical secondary batteries and square secondary batteries depending on the shape of the metal can.

[0004] Secondary batteries are made by welding the electrode tabs of an electrode assembly to a current collector. The current collector is connected to the electrode terminal, and by connecting the current collector to the electrode terminal, the electrode assembly and the electrode terminal are electrically connected.

[0005] The present invention provides a current collector capable of securing sufficient welding strength between an electrode terminal and a current collector when connecting the electrode terminal and the current collector, a secondary battery including the same, and a method for manufacturing the same.

[0006] The present invention provides a current collector in which a current collector and an electrode terminal can be easily joined, a secondary battery including the same, and a method for manufacturing the same.

[0007] A secondary battery according to one embodiment of the present invention includes an electrode assembly and a current collector. The electrode assembly may include an electrode portion, a plurality of first electrode tabs formed at one end of the electrode portion, and a plurality of second electrode tabs. The current collector may be disposed on an upper portion of the electrode portion and may include a first current collector, a second current collector, and a connecting portion. The first current collector may be welded to the plurality of first electrode tabs. The second current collector may be welded to the plurality of second electrode tabs. The connecting portion may be disposed between the first current collector and the second current collector and may include a current collector protrusion. The plurality of first electrode tabs may be bent in one direction toward the first current collector, and the plurality of second electrode tabs may be bent in an opposite direction to the first electrode tab toward the second current collector and may be welded, respectively.

[0008] In a secondary battery according to one embodiment of the present invention, the current collector protrusion may be made of a different material from the connecting portion.

[0009] In a secondary battery according to one embodiment of the present invention, the current collector may further have a support means at the bottom of the current collector protrusion.

[0010] In a secondary battery according to one embodiment of the present invention, the first current collector may extend vertically from a lower side of one side of the connecting portion, and the second current collector may extend vertically from an upper side of the other side of the connecting portion.

[0011] In a secondary battery according to one embodiment of the present invention, the connecting portion of the current collector may be formed of Cu or Ni, and the current collector protrusion may be formed of Al. The connecting portion and the current collector protrusion may be joined by cold bonding.

[0012] In a secondary battery according to one embodiment of the present invention, the connecting portion of the current collector may be formed of Cu or Ni, and the supporting means may be formed of Al. The connecting portion and the supporting means may be joined by cold bonding.

[0013] In a secondary battery according to one embodiment of the present invention, the current collector may be placed at one end of the electrode portion, in a portion where a plurality of first electrode tabs and a plurality of second electrode tabs are not formed.

[0014] In a secondary battery according to one embodiment of the present invention, an insulating member may be placed on the lower surface of the current collector.

[0015] In a secondary battery according to one embodiment of the present invention, the thickness of the current collector may be about 0.5 mm to 3.0 mm.

[0016] In a secondary battery according to one embodiment of the present invention, a plurality of micro grooves or a plurality of micro unevennesses may be formed on the upper surface of the current collector.

[0017] In a secondary battery according to one embodiment of the present invention, the electrode portion may include a plurality of first electrode members having first electrode tabs formed at first positions, and a plurality of second electrode members having second electrode tabs formed at second positions. The first electrode members and the second electrode members may have the same polarity.

[0018] A method for manufacturing a secondary battery according to one embodiment of the present invention includes a preparation step, a current collector arrangement step, a bending step, and a welding step. In the preparation step, an electrode assembly including 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 may be prepared. In the current collector arrangement step, a current collector may be arranged at one end of the electrode portion, in a portion where the plurality of first electrode tabs and the plurality of second electrode tabs are not formed. In the bending step, the plurality of first electrode tabs may be bent in one direction toward an upper surface of the first current collector of the current collector, and the plurality of second electrode tabs may be bent in an opposite direction to the first electrode tabs toward an upper surface of the second current collector of the current collector. In the welding step, the bent plurality of first electrode tabs and the plurality of second electrode tabs may be welded to the current collector. The current collector may include a first current collector, a second current collector, and a connection portion. The first current collector may be welded to the plurality of first electrode tabs. The second current collector may be electrically connected to the first current collector and welded to the plurality of second electrode tabs. The connecting part may have a first collector connected to one end and a second collector connected to the other end, and may have a collector projection.

[0019] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the current collector protrusion may be made of a different material from the connecting portion.

[0020] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the current collector may further have a support means at the bottom of the current collector protrusion.

[0021] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the first current collector may extend vertically from a lower side of one side of the connecting portion, and the second current collector may extend vertically from an upper side of the other side of the connecting portion.

[0022] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the connecting portion may be formed of Cu or Ni, and the collecting protrusion may be formed of Al. The connecting portion and the collecting protrusion may be joined by cold bonding.

[0023] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the connecting portion may be formed of Cu or Ni, and the supporting means may be formed of Al. The connecting portion and the supporting means may be joined by cold bonding.

[0024] In a method for manufacturing a secondary battery according to one embodiment of the present invention, an insulating member may be placed on the lower surface of the current collector.

[0025] In a method for manufacturing a secondary battery according to one embodiment of the present invention, the thickness of the current collector may be about 0.5 mm to 3.0 mm.

[0026] In a method for manufacturing a secondary battery according to one embodiment of the present invention, a plurality of micro-grooves or a plurality of micro-roughnesses may be formed on the upper surface of the current collector.

[0027] A current collector according to an embodiment of the present invention, a secondary battery including the same, and a manufacturing method thereof can secure sufficient welding strength between the electrode terminal and the current collector when connecting the electrode terminal and the current collector.

[0028] A current collector according to an embodiment of the present invention, a secondary battery including the same, and a manufacturing method thereof can easily combine a current collector and an electrode terminal.

[0029] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0030] FIG. 1 is a drawing showing a secondary battery according to one embodiment of the present invention.

[0031] FIG. 2 is a drawing showing a secondary battery according to one embodiment of the present invention.

[0032] FIG. 3 is a drawing showing an electrode assembly in which a plurality of first and second electrode tabs are formed on an electrode portion in a secondary battery according to one embodiment of the present invention.

[0033] FIG. 4a and FIG. 4b are drawings showing a first electrode member and a second electrode member in a secondary battery according to one embodiment of the present invention.

[0034] FIG. 5a and FIG. 5b are drawings showing a third electrode member and a fourth electrode member in a secondary battery according to one embodiment of the present invention.

[0035] FIG. 6 is a drawing showing a current collector in a secondary battery according to one embodiment of the present invention.

[0036] FIG. 7a and FIG. 7b are drawings showing a current collector in a secondary battery according to one embodiment of the present invention.

[0037] FIG. 8a and FIG. 8b are drawings showing a current collector in a secondary battery according to another embodiment of the present invention.

[0038] FIG. 9a and FIG. 9b are drawings showing a current collector in a secondary battery according to another embodiment of the present invention.

[0039] FIG. 10a and FIG. 10b are drawings showing a current collector in a secondary battery according to another embodiment of the present invention.

[0040] FIG. 11a, FIG. 11b, and FIG. 11c are drawings showing an insulating member arranged under a current collector in a secondary battery according to one embodiment of the present invention.

[0041] Figure 12 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment of the present invention.

[0042] FIG. 13 is a drawing 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.

[0043] FIG. 14a and FIG. 14b are drawings showing a state in which a current collector is arranged on one end of an electrode portion and welded to 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.

[0044] FIG. 15 is a drawing showing the welding progress direction when welding a current collector and a first electrode tab in a secondary battery according to one embodiment of the present invention.

[0045] FIG. 16 is a drawing showing a 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.

[0046] FIG. 17 is a drawing showing a state in which a cover member is placed at a portion where a current collector and a first electrode tab are welded in a secondary battery according to one embodiment of the present invention.

[0047] FIG. 18 is a drawing showing a state in which a cover member is placed at a portion where a current collector and first and second electrode tabs are welded in a secondary battery according to another embodiment of the present invention.

[0048] FIG. 19 is a drawing showing a state in which a cap assembly is coupled to an electrode assembly in a secondary battery according to one embodiment of the present invention.

[0049] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0050] The present invention is susceptible to various modifications and embodiments. Some embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0051] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0052] Hereinafter, some embodiments of the present invention will be described in detail with reference to the attached drawings. Please note that, where possible, identical components are represented by identical reference numerals throughout the drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted.

[0053] In the case of the negative terminal of a secondary battery, the exposed portion of the terminal structure is formed of an Al series metal, and the current collector is formed of a copper or nickel metal, so there is a problem that the welding bonding strength is weakened during the welding process with dissimilar metals.

[0054] The present invention provides a secondary battery structure capable of securing sufficient welding strength between an electrode terminal and a current collector and resolving connection complexity with the electrode terminal.

[0055] FIG. 1 is a drawing showing a secondary battery according to an embodiment of the present invention, FIG. 2 is a drawing showing a partially disassembled state of 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, FIGS. 4a and 4b are drawings showing a first electrode member and a second electrode member in a secondary battery according to an embodiment of the present invention, FIGS. 5a and 5b are drawings showing a third electrode member and a fourth electrode member in a secondary battery according to an embodiment of the present invention, and FIG. 6 is a drawing showing a current collector in a secondary battery according to an embodiment of the present invention.

[0056] As illustrated in FIGS. 1 and 2, a secondary battery (1000) according to one embodiment of the present invention includes a case (1100), an electrode assembly (1200), a current collector (1300), and a cap assembly (1400).

[0057] The case (1100) forms the exterior of the secondary battery (1000). The case (1100) may have a space formed therein to accommodate an electrode assembly (1200), and an opening formed on one side. In the present embodiment, the case (1100) has a rectangular parallelepiped shape, but is not limited thereto and may be modified in various ways. The case (1100) may be made of a sturdy material capable of protecting the electrode assembly (1200) accommodated therein. For example, the case (1100) may be made of a metal such as aluminum or stainless steel.

[0058] An electrolyte may be accommodated together with the electrode assembly (1200) inside the case (1100). The electrolyte may be composed 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 liquid, solid, or gel-like.

[0059] An electrode assembly (1200) is accommodated inside a case (1100). As illustrated in FIG. 3, the electrode assembly (1200) includes an electrode portion (1210), a plurality of first electrode tabs (1220), a plurality of second electrode tabs (1230), a plurality of third electrode tabs (1240), and a plurality of fourth electrode tabs (1250). The plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) are arranged 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. The plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) are arranged so as not to overlap in the width direction (y direction) and the length direction (x direction) of the electrode assembly (1200). A plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) are arranged at the other 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 plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are arranged so as not to overlap in the width direction (y direction) and the length direction (x direction) of the electrode assembly (1200).

[0060] Regarding the electrode part (1210) of the electrode assembly (1200), the electrode part (1210) includes 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.

[0061] 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). The plurality of first electrode members (1211) and the plurality of second electrode members (1212) may be formed by applying a positive electrode active material such as a transition metal oxide to a metal plate such as aluminum. 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. The plurality of third electrode members (1213) and the plurality of fourth electrode members (1214) may be formed by applying a negative electrode active material such as graphite or carbon to a metal plate such as copper or nickel. 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.

[0062] The separator is positioned between the 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, for example, polyethylene, polypropylene, or a composite thereof.

[0063] The electrode portion (1210) of the electrode assembly (1200) can be formed by sequentially positioning a separator between the first electrode member (1211) and the third electrode member (1213), and the second electrode member (1212) and the fourth electrode member (1214). In one embodiment, the electrode portion (1210) is formed by sequentially stacking the first electrode member (1211), the separator, the third electrode member (1213), and the separator tens to hundreds of times on one side of the electrode portion (1210), and sequentially stacking the second electrode member (1212), the separator, the fourth electrode member (1214), and the separator tens to hundreds of times on the other side of the electrode portion (1210). In another embodiment, the electrode portion (1210) may be formed by sequentially stacking a first electrode member (1211), a separator, a third electrode member (1213), a separator, a second electrode member (1212), a separator, a fourth electrode member (1214), and a separator, and then winding the separator. In another embodiment of the present invention, some of the electrode portions may be formed by sequentially stacking a first electrode member (1211), a separator, a third electrode member (1213), and a separator, and then winding the separator, and other parts may be formed by sequentially stacking a second electrode member (1212), a separator, a fourth electrode member (1214), and a separator, and then winding the separator.

[0064] In this embodiment, the electrode assembly (1200) has one electrode portion (1210), but in other embodiments, the electrode assembly (1200) may have a plurality of electrode portions (1210). The plurality of electrode portions (1210) may be electrically connected to each other.

[0065] An electrode tab (electrode tab, 1220, 1230, 1240, 1250) on which an active material is not applied is formed at one end of a plurality of first to fourth electrode members (1211, 1212, 1213, 1214). In one embodiment, the electrode members (1211, 1212, 1213, 1214) and the electrode tabs (1220, 1230, 1240, 1250) may be formed integrally by cutting a predetermined portion from a single metal plate using a laser or the like to leave the electrode members (1211, 1212, 1213, 1214) and the 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).

[0066] A first electrode tab (1220) is formed at a first position of a first electrode member (1211). A second electrode tab (1230) is formed at a second position of a second electrode member (1212) (Fig. 4). Similarly, a third electrode tab (1240) may be formed at a third position of a third electrode member (1213), and a fourth electrode tab (1250) may be formed at a fourth position of a fourth electrode member (1214) (Fig. 5).

[0067] A plurality of first electrode members (1211) and a plurality of third electrode members (1213) can be alternately stacked with a separator between them. A stack of a plurality of first electrode members (1211) and a plurality of third electrode members (1213) forms half of an electrode portion (1210).

[0068] A plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) can be alternately stacked with a separator between them. The stack of the plurality of second electrode members (1212) and the plurality of fourth electrode members (1214) forms the remaining half of the electrode portion (1210).

[0069] A stack of a plurality of first electrode members (1211) and a plurality of third electrode members (1213) and a stack of a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) are connected in the width direction of the electrode portion (1210). When forming the electrode assembly (1200), according to one embodiment, after stacking a plurality of first electrode members (1211) and a plurality of third electrode members (1213), a plurality of second electrode members (1212) and a plurality of fourth electrode members (1214) may be stacked.

[0070] When the plurality of first to fourth electrode members (1211, 1212, 1213, 1214) formed as described above are laminated together with a separator, the plurality of first electrode tabs (1220) overlap each other at a first position. The plurality of second electrode tabs (1230) overlap each other at a second position. In addition, the plurality of third electrode tabs (1240) overlap each other at a third position, and the plurality of fourth electrode tabs (1250) overlap each other at a fourth position. For example, among the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) having the same polarity, the plurality of first electrode tabs (1220) are grouped at the first position, and the plurality of second electrode tabs (1230) are grouped at the second position. The first position and the second position are spaced apart from each other on the electrode member, and the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230), which are respectively grouped, can be spaced apart in the width direction (y direction) and the length direction (x direction) of the electrode assembly (1200). In addition, among the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) having the same polarity, the plurality of third electrode tabs (1240) are grouped at the third position, and the plurality of fourth electrode tabs (1250) are grouped at the fourth position. The third position and the fourth position are spaced apart from each other on the electrode member, and the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250), which are respectively grouped, can be spaced apart in the width direction (y direction) and the length direction (x direction) of the electrode assembly (1200).

[0071] In order to stably weld a large number of electrode tabs (1220, 1230, 1240, 1250), electrode tabs of the same polarity are divided into two groups spaced apart from each other, aligned, and each group is welded on a current collector (1300). For example, one electrode tab is formed on one electrode member, but by making the positions where the electrode tabs are formed on each electrode member different, two groups of electrode tabs at different positions on the same polarity are formed after lamination of the electrode members. In another embodiment, two or more groups of electrode tabs at different positions on the same polarity may be formed.

[0072] A plurality of electrode tabs (1220, 1230, 1240, 1250) overlapping at each location can be connected to a current collector by ultrasonic welding, laser welding, etc. to facilitate the movement of current. The connection method is not limited to ultrasonic welding, laser welding, etc., and any connection method that facilitates the movement of current is possible.

[0073] As illustrated in FIG. 6, the current collector (1300) has a first current collector (1310), a second current collector (1320), a connecting portion (1330), and a current collector protrusion (1331).

[0074] According to one embodiment, a first electrode tab (1220) is welded to the first collector (1310), and a second electrode tab (1230) is welded to the second collector (1320).

[0075] The structure of the entire house (1300) will be described later.

[0076] The cap assembly (1400) seals the opening of the case (1100) in which the electrode assembly (1200) is accommodated. The cap assembly (1400) includes a cap plate (1410) and terminals (1420, 1420a).

[0077] The cap plate (1410) of the cap assembly (1400) may be a plate shape that covers 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 of 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.

[0078] A vent hole (1411) and an electrolyte injection port (1412) may be formed in the cap plate (1410). The vent hole (1411) is opened when the internal pressure of the case (1100) exceeds a reference value. In the present 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). Alternatively, the vent hole (1411) may be formed in both the case (1100) and the cap plate (1410), as needed. An electrolyte may be injected into the interior of the case (1100) through the electrolyte injection port (1412).

[0079] The terminals (1420, 1420a) may be formed to protrude from the cap plate (1410). The terminals (1420, 1420a) are electrically connected to the electrode tab (1220) through the current collector (1300). The terminals (1420, 1420a) may be in the shape of a plate having a circular or square shape.

[0080] A through hole (1422) may be formed in the terminal (1420, 1420a) of the cap assembly (1400). A collector projection (1331) is inserted into the through hole (1422). After the collector projection (1331) is inserted into the through hole (1422), the outer surface of the end of the collector projection (1331) and the inner surface of the end of the through hole (1422) may be joined by butt welding.

[0081] An insulating member (1430, 1430a) may be positioned between the terminal (1420, 1420a) of the cap assembly (1400) and the cap plate (1410). The insulating member (1430, 1430a) insulates the terminal (1420, 1420a) and the cap plate (1410) from each other.

[0082]

[0083] FIGS. 7A and 7B are drawings showing a current collector (1300) in a secondary battery according to one embodiment of the present invention, FIGS. 8A and 8B are drawings showing a current collector (1300) in a secondary battery according to another embodiment of the present invention, FIGS. 9A and 9B are drawings showing a current collector (1300) in a secondary battery according to another embodiment of the present invention, FIGS. 10A and 10B are drawings showing a current collector in a secondary battery according to another embodiment of the present invention, and FIGS. 11A, 11B, and 11C are drawings showing an insulating member disposed under a current collector (1300) in a secondary battery according to one embodiment of the present invention.

[0084] As illustrated in FIG. 7a, the current collector (1300) has a first current collector (1310), a second current collector (1320), and a connecting portion (1330).

[0085] According to one embodiment, the current collector (1300) has a 'Z' shape. The current collector (1300) extends with a first current collector (1310) and a second current collector (1320) connected to both sides of the connection portion (1330) centered on the connection portion (1330). The first current collector (1310) may be connected to a lower side of one side of the connection portion (1330), and the second current collector (1320) may be connected to an upper side of the other side of the connection portion (1330). For example, the first current collector (1310) and the second current collector (1320) are arranged to be misaligned in the length direction centered on the connection portion (1330). Due to the misalignment of the first collector (1310) and the second collector (1320), the shape in which the first collector (1310), the second collector (1320), and the connecting portion (1330) are connected may be in the shape of a staircase or a “Z.” The longitudinal center line (C1) of the first collector (1310) and the longitudinal center line (C2) of the second collector (1320) may be parallel to each other.

[0086] As the first collector (1310) and the second collector (1320) of the current collector (1300) are spaced apart from each other in the longitudinal direction (y direction) and the width direction (x direction) of the electrode assembly (1200), the first collector (1310) is disposed adjacent to one side of the electrode assembly (1200) in the width direction, and the second collector (1320) is disposed adjacent to the other side of the electrode assembly (1200) in the width direction. Accordingly, when a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) are welded to the first collector (1310) and the second collector (1320), respectively, they do not interfere with each other.

[0087] According to one embodiment, the first current collector (1310), the second current collector (1320), and the connection (1330) are formed integrally from the same material, and the first current collector (1310) and the second current collector (1320) are electrically connected. The width of the first current collector (1310) and the second current collector (1320) in the current collector (1300) may be about 0.3 to 0.5 times the width of the electrode assembly (1200). In addition, the current collector (1300) may have a thickness of about 0.5 mm to 3.0 mm. Since the present invention bends and welds the electrode tabs (1220, 1230, 1240, 1250) onto the current collector (1300), the current collector (1300) can be formed thick.

[0088] The connecting portion (1330) of the current collector (1300) has a current collector projection (1331). The current collector projection (1331) is connected to the through hole of the electrode terminal (1420, 1420a), thereby electrically connecting the current collector (1300) and the electrode terminal (1420, 1420a).

[0089] In another embodiment, the connecting portion (1330) may further include a supporting means (1333) at the bottom of the collecting protrusion (1331). The supporting means (1333) is positioned to contact the lower surface of the collecting protrusion (1331) and is formed of the same material as the collecting protrusion (1331). The supporting means (1333) serves to stably connect the collecting protrusion (1331) to the connecting portion (1330).

[0090] A plurality of micro-grooves or micro-roughnesses may be formed on the upper surface of the current collector (1300). The micro-grooves and micro-roughnesses are first melted during welding, and can allow the current collector (1300) to be better fused with the electrode tabs (1220, 1230, 1240, 1250).

[0091] According to one embodiment, two current collectors (1300) may be provided. In order to electrically connect the electrode terminals (1420, 1420a) of the electrode assembly (1200) and the cap assembly (1400), each current collector (1300) may be made of the same material as the plurality of first and second electrode tabs (1220, 1230), or may be made of the same material as the plurality of third and fourth electrode tabs (1240, 1250). For example, the current collector (1300) may be formed of aluminum, copper, or nickel.

[0092] Since the current collector (1300) connected to the positive electrode plate is formed of aluminum, when welding with the positive electrode terminal (1420) made of aluminum, sufficient welding strength can be secured as welding between similar materials. However, since the current collector (1300) connected to the negative electrode plate is made of copper or nickel, the bonding strength is weakened when welding with the negative electrode terminal (1420a) made of aluminum. Therefore, the present invention secures welding strength when connecting the current collector (1300) and the negative electrode terminal (1420a) by making the negative electrode terminal (1420a) of the cap assembly (1400) and the current collector protrusion (1331) of the current collector (1300) the same material.

[0093] Below, the third and fourth electrode members (1213, 1214), for example, the current collector (1300) connected to the negative plate, are described.

[0094] In order to electrically connect the electrode assembly (1200) and the negative terminal (1420a) of the cap assembly (1400), the first and second current collectors (1310, 1320) and the connection portion (1330) of the current collector (1300) may be formed of the same material as the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250), for example, a Cu or Ni series metal that is the same material as the negative electrode plate. The current collector protrusion (1331) of the current collector (1300) that is coupled to the negative terminal (1420a) of the cap assembly (1400) may be formed of an Al series metal that is the same material as the negative terminal (1420a). According to one embodiment, the current collector protrusion (1331) of the current collector (1300) may be formed of a different material from the connection portion (1330).

[0095] According to one embodiment, the connecting portion (1330) of the current collector (1300) is formed of a Cu or Ni series metal, and the current collector protrusion (1331) is formed of different types of metal, such as Al. The current collector protrusion (1331) is joined to the upper surface of the connecting portion (1330), for example, by cold bonding. Cold bonding refers to a method in which a high pressure applied to the metal expands the contact area by elongation between the joining materials, thereby expanding the actual contact area and joining them. An electrical connection with low contact resistance can be formed by cold bonding, which is a material bond within the actual contact area.

[0096] When the collector projection (1331) is positioned and pressed in the groove formed on the connecting portion (1330) of the current collector (1300), the contact surface between the inner surface of the groove and the end of the collector projection (1331) increases, thereby performing bonding. In the present embodiment, the collector projection (1331) is directly bonded to the connecting portion (1330), but in other embodiments, a support means (1333) positioned at the bottom of the collector projection (1331) may be coupled to the connecting portion (1330).

[0097] As illustrated in Fig. 8, the current collector protrusion (1331) may further be provided with a support means (1333) formed integrally with the current collector protrusion (1331) at the bottom. The current collector protrusion (1331) and the support means (1333) are formed integrally with a metal of the same material, and may be formed of Al. The support means (1333) is positioned in a groove formed on a connecting portion (1330) made of a Cu material, and the upper surface of the support means (1333) is pressed to perform bonding. As the contact area between the inner surface of the groove on the connecting portion (1330) and the lower surface of the support means (1333) increases, the support means (1333) is bonded to the connecting portion (1330). When the support means (1333) is joined to the connecting portion (1330), different types of metals can come into contact over a wider area compared to when the current collector protrusion (1331) is joined to the connecting portion (1330), enabling a more solid and stable joining.

[0098] In this embodiment, an example in which the current collector (1300) has a 'Z' shape has been described, but the present invention is not limited thereto, and a current collector protrusion (1331) can be coupled to the connecting portion (1330) in the same manner as a rectangular current collector (1300) as illustrated in FIG. 9. The connecting portion (1330) can be positioned between the first current collector (1310) and the second current collector (1320). The current collector protrusion (1331) is formed integrally with the current collector protrusion (1331) at the lower end thereof, and is positioned on the connecting portion (1330) of the current collector (1300) to be pressed. The lower surface of the supporting portion (1333) can be fitted into a groove formed on the connecting portion (1330), and the upper surface of the supporting portion (1333) is pressed to perform bonding. As the contact area between the inner surface of the groove on the connecting portion (1330) and the lower surface of the supporting means (1333) increases, the supporting means (1333) is joined to the connecting portion (1330). A case in which the current collector protrusion (1331) is directly connected to the connecting portion (1330) is not excluded.

[0099] Meanwhile, in another embodiment, the current collector protrusion (1331) and the support means (1333) may be connected to one side of the current collector (1300) (Fig. 10). For example, the current collector (1300) may have a connection part (1330), a first current collector part (1310), and a second current collector part (1320) sequentially arranged. The current collector protrusion (1331) may be formed integrally with the support means (1333), so that the lower surface of the support means (1333) may be fitted into a groove formed on the connection part (1330) and pressed. As the contact area between the inner surface of the groove on the connection part (1330) and the lower surface of the support means (1333) increases, the support means (1333) may be joined to the connection part (1330).

[0100] When the current collector (1300) is rectangular, the width of the first current collector (1310) and the second current collector (1320) may be about 0.5 to 0.8 times the width of the electrode assembly (1200).

[0101] An insulating member (1340) may be placed under the current collector (1300) (Fig. 10). The insulating member (1340) may be an insulating plate or an insulating film. The electrode tabs (1220, 1230) and the electrode portion (1210) may be further protected by the insulating member (1340).

[0102] Referring back to FIG. 2, the current collector (1300) can be placed at one end of the electrode portion (1210) in a portion where the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) are not formed. Since the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) are spaced apart in the longitudinal direction of the electrode assembly (1200), an area where the electrode tabs are not formed is formed on one side of the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230). The current collector (1300) is placed in this portion.

[0103] After the current collector (1300) is arranged, the plurality of first electrode tabs (1220) are bent toward the first current collector (1310), and the plurality of second electrode tabs (1230) are bent toward the second current collector (1320). For example, the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230) are bent in opposite directions.

[0104] After bending a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230), welding is performed on the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230). According to one embodiment, welding may be performed using a method such as ultrasonic welding or laser welding.

[0105] During welding, on the first collector (1310) side of the current collector (1300), welding may be performed from a plurality of first electrode tabs (1220) toward the first collector (1310), and on the second collector (1320) side of the current collector (1300), welding may be performed from a plurality of second electrode tabs (1230) toward the second collector (1320). In the present invention, since the electrode tabs are positioned on the current collector (1300) and welding is performed on the upper portion of the electrode tabs, there is no concern about damaging the separator provided in the electrode portion.

[0106] In addition, the current collector (1300) may be placed on the other end of the electrode portion (1210) in a portion where the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are not formed. Since the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are spaced apart in the longitudinal direction of the electrode assembly (1200), an area where no electrode tabs are formed is formed on one side of the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250). The current collector (1300) is placed in this portion.

[0107] After the current collector (1300) is placed, the plurality of third electrode tabs (1240) are bent toward the first current collector (1310), and the plurality of fourth electrode tabs (1250) are bent toward the second current collector (1320). For example, the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are bent in opposite directions.

[0108] After bending a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250), welding is performed on the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250). According to one embodiment, welding may be performed using a method such as ultrasonic welding or laser welding.

[0109] During welding, on the first collector (1310) side of the current collector (1300), welding may be performed from a plurality of third electrode tabs (1240) toward the first collector (1310), and on the second collector (1320) side of the current collector (1300), welding may be performed from a plurality of fourth electrode tabs (1250) toward the second collector (1320). In the present invention, since the electrode tabs are positioned on the current collector (1300) and welding is performed on the upper portion of the electrode tabs, there is no concern about damaging the separator provided in the electrode portion.

[0110] According to one embodiment of the present invention, when a current collector is welded on top of an electrode tab, the current collector must be thin to transfer heat to the electrode tab located below, which has resulted in reduced durability. However, the present invention secures the thickness of the current collector by bending and welding multiple tabs onto the current collector, thereby enabling the tabs to be welded to the current collector more efficiently.

[0111]

[0112] FIG. 12 is a flowchart showing a method for manufacturing a secondary battery according to an embodiment of the present invention, FIG. 13 is a drawing showing a state in which a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) are each grouped in a secondary battery according to an embodiment of the present invention, FIGS. 14a and 14b are drawings showing a state in which a current collector (1300) is arranged at one end of an electrode portion and welded with a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) in a secondary battery according to an embodiment of the present invention, and FIG. 15 is a drawing showing a welding progress direction when welding a current collector (1300) and a third electrode tab (1240) in a secondary battery according to an embodiment of the present invention. FIG. 16 is a drawing showing a state in which a current collector (1300) and third and fourth electrode tabs (1240, 1250) are welded in a secondary battery according to one embodiment of the present invention, FIG. 17 is a drawing showing a state in which a cover member is arranged on a current collector in a secondary battery according to one embodiment of the present invention, FIG. 18 is a drawing showing a state in which a cover member is arranged on a current collector in a secondary battery according to one embodiment of the present invention, and FIG. 19 is a drawing showing a part of a state in which a cap assembly is coupled to an electrode assembly in a secondary battery according to one embodiment of the present invention.

[0113] As illustrated in FIG. 12, in order to manufacture a secondary battery according to one embodiment of the present invention, an electrode assembly is prepared (S1100). The electrode assembly (1200) includes an electrode portion (1210), a plurality of first electrode tabs (1220) and a plurality of second electrode tabs (1230) formed at one end of the electrode portion (1210), and a plurality of third electrode tabs (1240) and a plurality of fourth electrode tabs (1250) at the other end of the electrode portion. However, although the present embodiment is described based on the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250), it goes without saying that the process can be performed in the same manner for the plurality of first electrode tabs (1220) and the plurality of second electrode tabs (1230).

[0114] When a plurality of electrode members forming an electrode portion (1210) are stacked, a plurality of third electrode tabs (1240) overlap each other at a third position, and a plurality of fourth electrode tabs (1250) overlap each other at a fourth position. For example, a plurality of third electrode tabs (1240) are grouped at a third position, and a plurality of fourth electrode tabs (1250) are grouped at a fourth position. The third position and the fourth position are spaced apart from each other on the electrode member (1210), and the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) that are grouped respectively can be spaced apart in the width direction and the length direction of the electrode assembly (1200). As illustrated in FIG. 13, the plurality of third electrode tabs (1240) that are grouped respectively can be arranged at one end of the electrode assembly in the width direction, and the plurality of fourth electrode tabs (1250) can be arranged at the other end of the electrode assembly in the width direction.

[0115] Next, a current collector (1300) is placed on one end of the electrode portion (S1200). In order to connect a plurality of third and fourth electrode tabs (1240, 1250) to the current collector (1300), in the present embodiment, electrode tabs (1240, 1250) of the same polarity (negative electrode) are divided into two groups and welded to the current collector (1300). The plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are spaced apart from each other in the width direction and the length direction of the electrode assembly (1200), and no electrode tabs are formed on one side of the plurality of third and fourth electrode tabs (1240, 1250). The current collector (1300) is placed on a portion of the electrode portion (1210) where no electrode tabs are formed on one side of the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) (Fig. 14a).

[0116] Next, the third electrode tab (1240) and the fourth electrode tab (1250) are each bent toward the upper surface of the current collector (1300) (S1300). The plurality of third electrode tabs (1240) are bent toward the upper surface of the first current collector (1310) of the current collector (1300), and the plurality of fourth electrode tabs (1250) are bent toward the upper surface of the second current collector (1320) of the current collector (1300). The plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250) are bent in opposite directions (Fig. 14b).

[0117] Next, the current collector (1300) and the third and fourth electrode tabs (1240, 1250) placed on the current collector (1300) are welded (S1400). The plurality of third electrode tabs (1240) are welded to the first current collector (1310) of the current collector (1300), and the plurality of fourth electrode tabs (1250) are welded to the second current collector (1320) of the current collector (1300). The welding may be performed on the upper portions of the plurality of third electrode tabs (1240) and the plurality of fourth electrode tabs (1250). The welding may be performed using a method such as ultrasonic welding or laser welding.

[0118] As illustrated in FIG. 15, during welding, welding may be performed from a plurality of third electrode tabs (1240) toward the first collector (1310) of the current collector (1300), and welding may be performed from a plurality of fourth electrode tabs (1250) toward the second collector (1320) of the current collector (1300).

[0119] Once welding is complete, the third and fourth electrode tabs (1240, 1250) and the current collector (1300) are connected (Fig. 16). Since the plurality of electrode tabs (1240, 1250) are welded directly onto the current collector (1300), the length of the electrode tabs does not need to be long, thereby reducing the cost, and since the bending space of the plurality of electrode tabs (1240, 1250) is not required, the capacity of the secondary battery can be further increased.

[0120] In this embodiment, multiple electrode tabs (1240, 1250) are bent and welded directly onto the current collector (1300), but in another embodiment, multiple electrode tabs may be welded in advance, such as the third electrode tabs (1240) and the fourth electrode tabs (1250), and then welded to the current collector (1300).

[0121] Meanwhile, as illustrated in FIG. 17, in one embodiment, after welding of a plurality of electrode tabs (1240, 1250) is completed, a cover member (1360) may be placed on the welded portion, for example, the first current collector (1310) and the second current collector (1320). The cover member (1360) may cover at least a portion of the electrode assembly (1200) and the current collector (1300).

[0122] The cover member (1360) may include an insulating material. The cover member (1360) may be an insulating tape. The collector projection (1331) and the support means (1333) may be exposed without being covered by the cover member (1360). The terminal (1420, 1420a) may be coupled to the collector projection (1331). By covering the welding portion with the cover member (1360), the insulating structure of the cover plate can be further simplified.

[0123] In this embodiment, 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 area fixed by the cover member (1360) can be minimized while covering the entire welded portion.

[0124] When the collector projection (1331) and the support means (1333) are arranged on one side of the collector (1300), the cover member (1360) can be arranged on the first collector portion (1310) and the second collector portion (1320) excluding the collector projection (1331) and the support means (1333, drawing to be revised) (Fig. 18). The collector projection (1331) is exposed without being covered by the cover member (1360), and can be coupled with the terminal (1420, 1420a).

[0125] The electrode assembly (1200) to which the current collector (1300) is welded is accommodated in the case (1100), and the cap assembly (1400) seals the opening of the case (1100). At this time, as illustrated in FIG. 19, after the current collector protrusion (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 protrusion (1331) and the inner surface of the end of the through-hole can be welded.

[0126] When the current collector (1300) is welded on the upper side of the electrode tabs (1220, 1230, 1240, 1250), the thickness of the current collector must be thin in order to transfer heat to the electrode tabs (1220, 1230, 1240, 1250) located on the lower side, which leads to weakened durability. However, the present invention can secure the thickness of the current collector (1300) by bending and welding a plurality of electrode tabs (1220, 1230, 1240, 1250) on the current collector (1300), and can weld the electrode tabs (1220, 1230, 1240, 1250) to the current collector (1300) more efficiently.

[0127] In addition, the present invention divides a plurality of electrode tabs having the same polarity into two groups (1220 / 1230 group and 1240 / 1250 group) and welds them, thereby stably welding the electrode tabs (1220, 1230, 1240, 1250) without any unwelded portions.

[0128] In one embodiment, the output of the welding device may be adjusted depending on the position of each electrode tab (1220, 1230, 1240, 1250) during the welding step.

[0129]

[0130] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. An electrode assembly having an electrode part, a plurality of first electrode tabs and a plurality of second electrode tabs formed at one end of the electrode part; and A current collector is provided, which is disposed on the upper portion of the electrode portion and has a first current collector welded to the plurality of first electrode tabs, a second current collector welded to the plurality of second electrode tabs, and a connecting portion disposed between the first current collector and the second current collector and having a current collector protrusion; A secondary battery in which the plurality of first electrode tabs are bent in one direction toward the first 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 and are welded respectively.

2. In paragraph 1, In the above whole house, A secondary battery in which the above-mentioned current collector protrusion is formed of a different material from the above-mentioned connecting portion.

3. In paragraph 1, The above-mentioned entire house, A secondary battery further comprising a supporting means at the bottom of the above-mentioned current collector.

4. In paragraph 1, A secondary battery in which the first collector extends vertically from the lower side of one side of the connecting portion, and the second collector extends vertically from the upper side of the other side of the connecting portion.

5. In paragraph 2, A secondary battery in which the connecting portion is formed of Cu or Ni and the collecting protrusion is formed of Al, wherein the connecting portion and the collecting protrusion are joined by cold bonding.

6. In paragraph 3, A secondary battery in which the connecting portion is formed of Cu or Ni and the supporting means is formed of Al, wherein the connecting portion and the supporting means are joined by cold bonding.

7. In paragraph 1, A secondary battery in which the above-mentioned collector is disposed at one end of the electrode portion, in a portion where the plurality of first electrode tabs and the plurality of second electrode tabs are not formed.

8. In paragraph 1, A secondary battery in which an insulating member is placed on the lower surface of the above-mentioned collector.

9. In paragraph 1, A secondary battery having a thickness of the entire body of the battery of 0.5 mm to 3.0 mm.

10. In paragraph 1, A secondary battery having a plurality of micro-grooves or micro-roughnesses formed on the upper surface of the above-mentioned collector.

11. In paragraph 1, The above electrode part It comprises a plurality of first electrode members having first electrode tabs formed at first positions and a plurality of second electrode members having second electrode tabs formed at second positions. A secondary battery wherein the first electrode member and the second electrode member have the same polarity.

12. A preparatory step in which an electrode assembly having an electrode part and a plurality of first electrode tabs and a plurality of second electrode tabs formed at one end of the electrode part is prepared; A current collector arrangement step in which a current collector is arranged on one end of the electrode portion, in a portion where the plurality of first electrode tabs and the plurality of second electrode tabs are not formed; A bending step in which the plurality of first electrode tabs are bent in one direction toward the upper surface of 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 upper surface of the second current collector of the current collector; and A welding step in which the plurality of bent first electrode tabs and the plurality of second electrode tabs and the current collector are welded; The above entire house A first collector portion welded to a plurality of first electrode tabs, A second collector electrically connected to the first collector and welded to a plurality of second electrode tabs, and A method for manufacturing a secondary battery, comprising: a first current collector connected to one end; a second current collector connected to the other end; and a connecting portion having a current collector projection.

13. In paragraph 12, A method for manufacturing a secondary battery in which the above-mentioned current collector protrusion is made of a different material from the above-mentioned connecting portion.

14. In paragraph 12, The above-mentioned entire house, A method for manufacturing a secondary battery further comprising providing a support means at the bottom of the above-mentioned current collector.

15. In paragraph 12, In the above whole house, A method for manufacturing a secondary battery, wherein the first collector extends vertically from a lower side of one side of the connecting portion, and the second collector extends vertically from an upper side of the other side of the connecting portion.

16. In paragraph 13, A method for manufacturing a secondary battery, wherein the connecting portion is formed of Cu or Ni and the collecting protrusion is formed of Al, wherein the connecting portion and the collecting protrusion are joined by cold bonding.

17. In paragraph 14, A method for manufacturing a secondary battery, wherein the connecting portion is formed of Cu or Ni and the supporting means is formed of Al, wherein the connecting portion and the supporting means are joined by cold bonding.

18. In paragraph 12, A method for manufacturing a secondary battery, characterized in that an insulating member is placed on the lower surface of the above-mentioned collector.

19. In paragraph 12, A method for manufacturing a secondary battery wherein the thickness of the above-mentioned collector is 0.5 mm to 3.0 mm.

20. In paragraph 12, A method for manufacturing a secondary battery, wherein a plurality of micro-grooves or a plurality of micro-roughnesses are formed on the upper surface of the above-mentioned collector.