Secondary battery

Abstract

The present invention provides a secondary battery enabling a thin film tab and a current collecting member to be stably connected as the number of electrode assemblies increases. The secondary battery, according to one aspect of the present invention, comprises: a case; a plurality of electrode assemblies; electrode tab bundles provided to electrodes of the plurality of electrode assemblies; a current collecting member coupled to the electrode tab bundles of the plurality of electrode assemblies; and a cap assembly. The current collecting member may comprise: a main support plate on which a connection terminal connected to an external terminal is positioned; and a plurality of branches extendedly formed on the side surface of the main support plate along the width direction of the electrode assemblies, and to which the electrode tab bundles are coupled.

Description

secondary battery

[0001] The present application claims the benefit of priority based on Korean Patent Application No. 10-2025-0038280 dated March 25, 2025, Korean Patent Application No. 10-2025-0099304 dated July 22, 2025, Korean Patent Application No. 10-2026-0030799 dated February 19, 2026, and Korean Patent Application No. 10-2026-0052740 dated March 24, 2026, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of the specification.

[0002] The present invention relates to a secondary battery capable of charging and discharging.

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance secondary batteries capable of repeated charging and discharging is actively underway.

[0004] Currently commercialized rechargeable batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium-ion batteries. Among these, lithium-ion batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density.

[0005] These lithium secondary batteries primarily use lithium-based oxides and carbon materials as the positive and negative active materials, respectively. Additionally, the lithium secondary battery comprises a positive plate and a negative plate coated with these positive and negative active materials, respectively; an electrode assembly in which the positive and negative plates are arranged with a separator in between; and an outer casing that seals and encloses the electrode assembly together with an electrolyte.

[0006] Meanwhile, lithium 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. Furthermore, can-type secondary batteries can be further classified into cylindrical batteries and prismatic batteries depending on the shape of the metal can.

[0007] In the case of prismatic batteries, multiple thin-film tabs connected to the electrode plates are assembled into a single pre-welded unit and then welded to the current collector. As the thickness of the electrode assembly increases, the length of the thin-film tabs required for pre-welding becomes longer, and it is necessary to stably connect these thin-film tabs to the current collector.

[0008] The objective of the present invention is to provide a secondary battery capable of increasing energy density per unit volume by reducing the space occupied by thin film tabs, etc., inside the case.

[0009] Another objective of the present invention is to provide a secondary battery capable of reducing resistance to current as the length of the thin film tab increases during the process in which current reaches the electrode assembly through an external terminal.

[0010] Another objective of the present invention is to provide a secondary battery capable of stably connecting a thin film tab and a current collector as the number of electrode assemblies increases.

[0011] A secondary battery according to one aspect of the present invention comprises a case, a plurality of electrode assemblies each comprising an electrode and accommodated in the case, an electrode tab bundle formed on each electrode of the plurality of electrode assemblies, a current collector member coupled to the electrode tab bundle of the plurality of electrode assemblies, and a cap assembly that seals the case and has an external terminal connected to the current collector member located thereon, wherein the current collector member may include a main support plate having a connection terminal connected to the external terminal located thereon, and a plurality of branches extending along the width direction of the electrode assembly on the side of the main support plate and to which the electrode tab bundle is coupled.

[0012] According to one aspect of the present invention, the ends of the electrode tab bundles can be fixedly joined to each other by a first welding.

[0013] According to one aspect of the present invention, the end of the electrode tab bundle can be fixed on the plurality of branches by a second welding.

[0014] According to one aspect of the present invention, a second welded area formed at the end by the second weld may overlap at least partially with a first welded area formed at the end by the first weld.

[0015] According to one aspect of the present invention, the second welding area may be located within the first welding area.

[0016] According to one aspect of the present invention, the first welding area may be located in contact with the side end of the electrode tab bundle.

[0017] According to one aspect of the present invention, the first welding area may be positioned spaced apart from the side end of the electrode tab bundle.

[0018] According to one aspect of the present invention, the area of ​​the first weld region formed at the end by the first weld may be 1.1 to 5 times the area of ​​the second weld region formed at the end by the second weld.

[0019] According to one aspect of the present invention, the length of the first welded area in the width direction may be greater than the length of the second welded area.

[0020] According to one aspect of the present invention, the plurality of branches may include a first branch and a second branch spaced apart from each other in the thickness direction of the electrode assembly intersecting the width direction.

[0021] According to one aspect of the present invention, different numbers of electrode tab bundles may be coupled to the first branch and the second branch.

[0022] According to one aspect of the present invention, two electrode tab bundles may be coupled to the first branch, and one electrode tab bundle may be coupled to the second branch.

[0023] According to one aspect of the present invention, the two electrode tab bundles and the one electrode tab bundle may be arranged in a line along the thickness direction.

[0024] According to one aspect of the present invention, the two electrode tab bundles are bent to face each other along the thickness direction and coupled to the first branch, and the one electrode tab bundle can be bent in the same direction as the adjacent electrode tab bundle among the two electrode tab bundles and coupled to the second branch.

[0025] According to one aspect of the present invention, the plurality of electrode assemblies includes three electrode assemblies arranged parallel to each other along the thickness direction, and one electrode tab bundle may be located in each of the three electrode assemblies.

[0026] According to one aspect of the present invention, the first width of the first branch in the thickness direction may be greater than the second width of the second branch.

[0027] According to one aspect of the present invention, the first width of the first branch and the second width of the second branch may satisfy the following formula 1.

[0028] According to one aspect of the present invention, the first area of ​​the first branch and the second area of ​​the second branch may satisfy the following formula 2.

[0029] According to one aspect of the present invention, the separation distance between the first branch and the second branch can satisfy the following Equation 3.

[0030] According to one aspect of the present invention, the electrode tab bundle may be coupled to the upper surface of the first branch and the second branch.

[0031] According to one aspect of the present invention, the electrode tab bundles of the plurality of electrode assemblies may be arranged in a row along the thickness direction.

[0032] According to one aspect of the present invention, the same number of electrode tab bundles may be coupled to the first branch and the second branch.

[0033] According to one aspect of the present invention, the connecting terminal may be disposed adjacent to the side end of the electrode assembly in the width direction.

[0034] According to one aspect of the present invention, the connecting terminal may be cylindrical in shape.

[0035] According to one aspect of the present invention, the main support plate and the plurality of branches may form the same plane.

[0036] According to one aspect of the present invention, the flatness of the main support plate and the plurality of branches may be 0.05 mm to 2 mm.

[0037] According to one aspect of the present invention, the total length of the current collector in the width direction may be 0.5 to 0.75 times the length of the electrode assembly.

[0038] According to one aspect of the present invention, an insulating holder that supports the current collector may be coupled to the lower part of the current collector.

[0039] According to one aspect of the present invention, at least a portion of the electrode tab bundle is folded parallel to the upper surface of the electrode assembly by an insulating tape, and the insulating tape may be positioned between the current collector and the upper surface of the electrode assembly.

[0040] According to one aspect of the present invention, a first current collecting member and a second current collecting member, each connected to an electrode of different polarities, may be symmetrical with respect to an axis extending in the thickness direction of the electrode assembly that intersects the width direction.

[0041] According to one aspect of the present invention, a first current collecting member and a second current collecting member, each connected to electrodes of different polarities, may be point-symmetric with respect to the center point of the electrode assembly.

[0042] According to one aspect of the present invention, the case or the cap assembly further includes a vent portion formed therein, wherein the long axis direction of the vent portion may be parallel to or intersect with the width direction.

[0043] A secondary battery according to one embodiment of the present invention can increase energy density per unit volume by reducing the space occupied by thin film tabs, etc., inside the case.

[0044] In addition, a secondary battery according to one embodiment of the present invention can reduce resistance to current due to an increase in the length of the thin film tab during the process in which current reaches the electrode assembly through an external terminal.

[0045] In addition, a secondary battery according to one embodiment of the present invention can stably connect a thin film tab and a current collector as the number of electrode assemblies increases.

[0046] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention.

[0047] Figure 2 is a cross-sectional view taken along the line A1-A1 in Figure 1.

[0048] FIG. 3 is a perspective view illustrating a state in which a current collecting member is coupled to a plurality of electrode assemblies according to a first embodiment of the present invention.

[0049] FIG. 4 is a plan view illustrating a plurality of electrode assemblies of FIG. 3.

[0050] FIG. 5 is a plan view illustrating a state in which an electrode tab bundle is coupled to a current collector member according to the first embodiment of the present invention.

[0051] FIG. 6 is a perspective view illustrating a current collecting member according to a first embodiment of the present invention.

[0052] Figure 7 is a cross-sectional view taken along the line A2-A2 in Figure 3.

[0053] FIG. 8 is a side view of an electrode having an electrode tab bundle formed thereon according to the first embodiment of the present invention.

[0054] FIG. 9 is a drawing illustrating the state in which a bundle of electrode tabs of a plurality of electrode assemblies is first welded according to the first embodiment of the present invention.

[0055] FIG. 10 is a perspective view illustrating a current collecting member according to a second embodiment of the present invention.

[0056] FIG. 11 is a cross-sectional view illustrating the combined state of the current collector and the electrode assembly of FIG. 10.

[0057] FIG. 12 is a plan view illustrating a state in which an electrode tab bundle is coupled to a current collector member according to a third embodiment of the present invention.

[0058] FIG. 13 is a side view of an electrode having an electrode tab bundle formed thereon according to a third embodiment of the present invention.

[0059] FIG. 14 is a plan view illustrating a state in which a current collecting member is coupled to a plurality of electrode assemblies according to a fourth embodiment of the present invention.

[0060] FIG. 15 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the fifth embodiment of the present invention.

[0061] FIG. 16 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the 6th embodiment of the present invention.

[0062] FIG. 17 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the seventh embodiment of the present invention.

[0063] FIG. 18 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the eighth embodiment of the present invention.

[0064] FIG. 19 is a perspective view of a vent portion viewed from below according to the ninth embodiment of the present invention.

[0065] FIG. 20 is a perspective view illustrating a secondary battery according to the 10th embodiment of the present invention.

[0066] FIG. 21 is a top view of the secondary battery of FIG. 20.

[0067] FIG. 22 is a perspective view of a vent portion viewed from below according to the 11th embodiment of the present invention.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] A secondary battery according to the first embodiment of the present invention will be described below.

[0072] FIG. 1 is a perspective view illustrating a secondary battery according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line A1-A1 in FIG. 1, and FIG. 3 is a perspective view illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to a first embodiment of the present invention.

[0073] Referring to FIGS. 1 to 3, the secondary battery (10) according to the present embodiment may include a plurality of electrode assemblies (500) including a positive electrode (11) and a negative electrode (12), a case (100) that accommodates the electrode assemblies (500), a cap plate (21) coupled to the case (100), external terminals (23, 24) installed on the cap plate (21), an upper insulating member (29) disposed between the cap plate (21) and the electrode assembly (500), and a vent portion (50) disposed on the cap plate (21). Meanwhile, in the present embodiment, the cap assembly (20) may include a cap plate (21), external terminals (23, 24), an upper insulating member (29), a gasket (25, 26), etc.

[0074] Each electrode assembly (500) performs charging and discharging and can be formed in various forms such as an all-solid electrode assembly, a lithium-ion electrode assembly, a sodium-ion electrode assembly, etc.

[0075] The electrode assembly (500) includes an anode (11), a cathode (12), and a separator (13) interposed between the anode (11) and the cathode (12), and the anode (11), separator (13), and cathode (12) may be formed in a stacked structure or in a structure wound in the form of a jelly roll.

[0076] Additionally, the electrode assembly (500) may be structured such that an anode (11) and a cathode (12) are alternately inserted between separators (13) that are folded in a zigzag shape. Additionally, the electrode assembly (500) may be formed in various forms, such as an all-solid type that does not have a separator.

[0077] The positive electrode (11) and the negative electrode (12), which are electrodes, may include a coated portion, which is an area where an active material is applied to a metal foil, and a non-coated portion, where no active material is applied. The positive electrode non-coated portion (11a, 11b, 11c) may protrude from the side end of the positive electrode (11), and the negative electrode non-coated portion (12a, 12b, 12c) may protrude from the side end of the negative electrode (12). The positive electrode non-coated portion (11a, 11b, 11c) and the negative electrode non-coated portion (12a, 12b, 12c) may protrude in the same direction, but in the direction toward the cap plate (21), that is, in the longitudinal direction (z-axis direction) of the electrode assembly (500).

[0078] The positive electrode unpaired portions (11a, 11b, 11c) and the negative electrode unpaired portions (12a, 12b, 12c) are formed in the shape of tabs and can be spaced apart in the width direction (y-axis direction) of the electrode assembly (500). The positive electrode unpaired portions (11a, 11b, 11c) and the negative electrode unpaired portions (12a, 12b, 12c) can be stacked in the thickness direction (x-axis direction) of the electrode assembly (500). At this time, the stacked positive electrode unpaired portions (11a, 11b, 11c) can form a first electrode tab bundle (11a, 11b, 11c), and the stacked negative electrode unpaired portions (12a, 12b, 12c) can form a second electrode tab bundle (12a, 12b, 12c).

[0079] Additionally, the first electrode tab bundle (11a, 11b, 11c) may be electrically connected to the first external terminal (23) via the first current collector (310), and the second electrode tab bundle (12a, 12b, 12c) may be electrically connected to the second external terminal (24) via the current collector (42). A detailed description of the combined structure of the first electrode tab bundle (11a, 11b, 11c) and the first current collector (310) and the combined structure of the second electrode tab bundle (12a, 12b, 12c) and the second current collector (330) in this embodiment will be provided later.

[0080] A separator (13) is placed between the positive electrode (11) and the negative electrode (12), and the separator (13) prevents short circuits and enables the movement of ions. If the secondary battery (10) is made of an all-solid-state battery, a solid electrolyte may be placed between the positive electrode (11) and the negative electrode (12) instead of the separator (13).

[0081] The case (100) may be formed in the shape of a box having an internal space for accommodating an electrode assembly (500). The case (100) may be formed in various shapes, such as prismatic or cylindrical. A plurality of electrode assemblies (500) may be inserted into the case (100).

[0082] An electrolyte may be contained together with an electrode assembly (500) inside the case (100). The electrolyte may be in the form of a liquid, solid, or gel.

[0083] The cap plate (21) is made of a plate material that covers the opening of the case (100) and may have a shape corresponding to the shape of the opening of the case (100). The cap plate (21) may be fixed to the case (100) by welding.

[0084] In the cap plate (21), an electrolyte injection port (H1) for injecting the electrolyte and a vent hole (H2) in which a vent portion (50) is installed may be formed. A sealing plug (28) that blocks the electrolyte injection port (H1) is installed in the electrolyte injection port (H1), and a vent portion (50) that opens at a preset pressure may be formed in the vent hole (H2).

[0085] In this embodiment, the vent portion (50) may extend in the width direction (y-axis direction). The vent portion (50) is formed in a shape that extends in the width direction (y-axis direction) and may have a shape such as a rectangle, an oblong, or a rounded rectangle.

[0086] Additionally, the vent portion (50) can be fixed to the cap plate (21) by welding. The vent portion (50) can be fixed to the lower surface of the cap plate (21), but it can also be fixed to the upper surface of the cap plate (21).

[0087] The vent portion (50) may include two side notches (52, 53) and a connecting notch (51) connecting the side notches (52, 53). The connecting notch (51) and the side notches (52, 53) may be formed as long, continuous grooves and may be formed as grooves having a trapezoidal cross-section. However, the present invention is not limited thereto, and the connecting notch (51) and the side notches (52, 53) may have cross-sections of various shapes, such as triangles or arcs.

[0088] The connecting notch (51) is formed in a curved shape and can form a wave shape or an S shape. The two side notches (52, 53) are formed in an arc shape and are formed convexly in opposite directions, but can protrude convexly toward the outer side in the width direction (y-axis direction) of the vent portion (50). The first side notch (52) and the second side notch (53) are connected to the connecting notch (51), and the first side notch (52) and the second side notch (53) have the same structure and can be arranged symmetrically.

[0089] In this embodiment, the vent portion (50) is formed to extend along the width direction (y-axis direction), and the gap between the first current collector (310) and the second current collector (330) is formed large so that even if the vent portion (50) is arranged in the width direction (y-axis direction), gas can be discharged smoothly without interference from the first current collector (310) and the second current collector (330).

[0090] An upper insulating member (29) may be disposed on the lower part of the cap plate (21), and the upper insulating member (29) may be formed as a plate parallel to the cap plate (21) and may extend in the width direction (y-axis direction) of the electrode assembly (500).

[0091] External terminals (23, 24) are coupled to the cap plate (21), and one or two external terminals (23, 24) may be installed on the cap plate (21). When two external terminals (23, 24) are installed on the cap plate (21), the first external terminal (23) may be a positive terminal and the second external terminal (24) may be a negative terminal. When one external terminal is installed on the cap plate (21), the case (100) may be charged as a negative terminal.

[0092] The first external terminal (23) and the second external terminal (24) may be formed in the shape of a plate. An insulating gasket (25) may be installed between the first external terminal (23) and the cap plate (21), and an insulating gasket (26) may also be installed between the second external terminal (24) and the cap plate (21). Additionally, the gaskets (25, 26) may extend downward and be located between the current collector (310, 330) and the cap plate (21). The gaskets (25, 26) may be formed as a single component or divided into multiple components.

[0093] The first external terminal (23) and the second external terminal (24) are formed in a plate shape, and a hole may be formed in the center of the first external terminal (23) and the second external terminal (24) into which a connecting terminal (317, 337) of the first current collecting member (310) or the second current collecting member (330) is inserted.

[0094] In this embodiment, the electrode assembly (500) may include three electrode assemblies. Each electrode assembly (510, 530, 550) may be an electrode assembly having the same internal structure.

[0095] A plurality of electrode assemblies (510, 530, 550) may be stacked along the thickness direction (x-axis direction) of the electrode assembly (500). Each of the plurality of electrode assemblies (510, 530, 550) may include a first electrode tab bundle (11a, 11b, 11c) which is one positive electrode and a second electrode tab bundle (12a, 12b, 12c) which is one negative electrode. In each electrode assembly (510, 530, 550), an equal number of first electrode tab bundles (11a, 11b, 11c) and an equal number of second electrode tab bundles (12a, 12b, 12c) may be formed. That is, the first electrode tab bundles (11a, 11b, 11c) of each of the first electrode assembly (510), the second electrode assembly (530), and the third electrode assembly (550) may have the same number of tabs stacked, and the second electrode tab bundles (12a, 12b, 12c) of each of the first electrode assembly (510), the second electrode assembly (530), and the third electrode assembly (550) may also have the same number of tabs stacked.

[0096] At this time, a plurality of first electrode tab bundles (11a, 11b, 11c) may be arranged in a line along the thickness direction (x-axis direction), and a plurality of second electrode tab bundles (12a, 12b, 12c) may also be arranged in a line along the thickness direction (x-axis direction). A plurality of first electrode tab bundles (11a, 11b, 11c) may be located at one end side along the width direction (y-axis direction) of the electrode assembly (500), and a plurality of second electrode tab bundles (12a, 12b, 12c) may be located at the other end side along the width direction (y-axis direction) of the electrode assembly (500).

[0097] FIG. 4 is a plan view illustrating a plurality of electrode assemblies of FIG. 3, FIG. 5 is a plan view illustrating a state in which an electrode tab bundle is coupled to a current collecting member according to the first embodiment of the present invention, FIG. 6 is a perspective view illustrating a current collecting member according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view taken along the line A2-A2 in FIG. 3, FIG. 8 is a side view of an electrode having an electrode tab bundle formed according to the first embodiment of the present invention, FIG. 9 is a view illustrating a state in which the electrode tab bundle of a plurality of electrode assemblies according to the first embodiment of the present invention is first welded.

[0098] Referring to FIGS. 4 to 9, in this embodiment, a first electrode assembly (510), a second electrode assembly (530), and a third electrode assembly (550) are stacked along the thickness direction (x-axis direction), and the first electrode tab bundles (11a, 11b, 11c) of the positive electrode are coupled with the first current collector (310), and the second electrode tab bundles (12a, 12b, 12c) of the negative electrode can be coupled with the second current collector (330).

[0099] In this embodiment, the first current collector (310) may include a main support plate (311) and a plurality of branches (313, 315). The main support plate (311) may support the first connection terminal (317) as a flat plate-shaped member. The first connection terminal (317) is located on the upper surface of the main support plate (311), and the first connection terminal (317) may be electrically connected to the first external terminal (23) coupled to the cap plate (21). At this time, the first connection terminal (317) may have a cylindrical shape.

[0100] A plurality of branches (313, 315) may be formed on the side of the main support plate (311). Each of the plurality of branches (313, 315) may be formed to extend along the width direction (y-axis direction). The plurality of branches (313, 315) may also be flat plate-shaped members, just like the main support plate (311). In this embodiment, the main support plate (311) of the first current collector (310) and the plurality of branches (313, 315) may form a single flat plate-shaped member, that is, the same plane.

[0101] The first branch (313) and the second branch (315) may have a rectangular shape formed long in the width direction (y-axis direction). Accordingly, the first current collector (310) according to the present embodiment may have a roughly U-shape.

[0102] A plurality of branches (313, 315) may include a first branch (313) and a second branch (315) each extended and formed on the side of the main support plate (311). The first branch (313) and the second branch (315) may be spaced apart from each other along the thickness direction (x-axis direction). At this time, the first branch (313) and the second branch (315) may be spaced apart by a spacing distance (CD).

[0103] In this embodiment, the width of the first branch (313) and the width of the second branch (315) may be different from each other. The first branch (313) may have a first width (C1), and the second branch (315) may have a second width (C2). Here, the first width (C1) and the second width (C2) represent the widths of the first branch (313) and the second branch (315) in the thickness direction (x-axis direction), respectively.

[0104] Specifically, the first width (C1) of the first branch (313) may be larger than the second width (C2) of the second branch (315). Accordingly, two electrode tab bundles, namely the first electrode tab bundle (11a) and the first electrode tab bundle (11b), may be combined on the upper surface of the first branch (313), and one electrode tab bundle, namely the first electrode tab bundle (11c), may be combined on the upper surface of the second branch (315). That is, different numbers of electrode tab bundles may be combined on the first branch (313) and the second branch (315).

[0105] On the upper surface of the first branch (313), the first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be bent and joined so as to face each other along the thickness direction (x-axis direction). The first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be bent in opposite directions along the thickness direction (x-axis direction) and welded to the upper surface of the first branch (313).

[0106] On the upper surface of the second branch (315), one electrode tab bundle, namely the first electrode tab bundle (11c), can be bent in the same direction as the adjacent first electrode tab bundle (11b) and joined.

[0107] Accordingly, the first electrode tab bundle (11b) and the first electrode tab bundle (11c) are bent in the same direction, and the first electrode tab bundle (11a) is bent in a different direction from the first electrode tab bundle (11b) and the first electrode tab bundle (11c) and can be joined on the branch.

[0108] At this time, the first width (C1) of the first branch (313) and the second width (C2) of the second branch (315) can satisfy the following [Equation 1.

[0109] [Formula 1] 1 / 3*C1 ≤ C2 ≤ 1 / 1.5*C1

[0110] This means that the first width (C1) of the first branch (313) may be approximately 1.5 to 3 times the second width (C2) of the second branch (315). If the first width (C1) of the first branch (313) is smaller than 1.5 times the second width (C2) of the second branch (315), a portion of the first electrode tab bundle (11a) and the first electrode tab bundle (11b) coupled to the upper surface of the first branch (313) may overlap each other. As a result, the electrical resistance of the first electrode tab bundle (11a) and the first electrode tab bundle (11b) coupled to the upper surface of the first branch (313) increases, and the coupling force with the first current collector (310) may be weakened as the first electrode tab bundle (11a) and the first electrode tab bundle (11b) overlap. Meanwhile, if the first width (C1) of the first branch (313) is greater than three times the second width (C2) of the second branch (315), the area of ​​the first current collector (310) increases, and the resistance to the current passing through the first current collector (310) may increase.

[0111] Meanwhile, the first area (S1) of the first branch (313) and the second area (S2) of the second branch (315) can satisfy the following [Equation 2].

[0112] [Equation 2] 1 / 3*S1 ≤ S2 ≤ 1 / 1.5*S1

[0113] This means that the first area (S1) of the first branch (313) may be approximately 1.5 to 3 times the second area (S2) of the second branch (315). If the first area (S1) of the first branch (313) is smaller than 1.5 times the second area (S2) of the second branch (315), a portion of the first electrode tab bundle (11a) and the first electrode tab bundle (11b) coupled to the upper surface of the first branch (313) may overlap each other. Meanwhile, if the first area (S1) of the first branch (313) is larger than 3 times the second area (S2) of the second branch (315), the total area of ​​the first current collector (310) increases, and the resistance to the current passing through the first current collector (310) may increase.

[0114] Meanwhile, the first width (C1) of the first branch (313), the second width (C2) of the second branch (315), and the separation distance (CD) can satisfy the following [Equation 3].

[0115] [Equation 3] 1 / 2 * C2 ≤ CD ≤ C1

[0116] This means that the separation distance (CD) may be less than or equal to the first width (C1) of the first branch (313) and greater than or equal to half the second width (C2) of the second branch (315). If the separation distance (CD) falls outside the above range, the electrode tab bundle to be coupled to the upper surface of the branch cannot be coupled to the upper surface of the branch by protruding upward from the center of each electrode assembly, and the electrode tab bundle is coupled to the upper surface of the branch by protruding upward from a position adjacent to the side of the electrode assembly, away from the center of each electrode assembly. In this case, the length of the electrode tab bundle protruding from each electrode assembly increases compared to the case where it is placed in the center, which may increase the manufacturing cost.

[0117] Additionally, the length (CC) of the first branch (313) and the second branch (315) in the width direction (y-axis direction) may be 0.6 to 0.9 times the total length (CB) of the first current collector (310). That is, the length (CC) of the first branch (313) and the second branch (315) may occupy approximately half or more of the total length (CB) of the first current collector (310). At this time, the length (IT1) of the first electrode tab bundle (11a, 11b, 11c) coupled to the upper surface of the first branch (313) and the second branch (315) may be 0.7 to 0.95 times the length (CC) of the first branch (313) and the second branch (315). Likewise, the length (IT1) of the first electrode tab bundle (11a, 11b, 11c) may occupy more than half of the length (CC) of the first branch (313) and the second branch (315).

[0118] Meanwhile, the total length of the current collector (300), which is the sum of the length (CB) of the first current collector (310) and the length (CB) of the second current collector (330) in the width direction (y-axis direction), may be 0.5 to 0.75 times the length (L1) of the electrode assembly (500). The above range may represent the ratio of the total length of the electrode assembly (500) that the current collector (300) occupies in the width direction (y-axis direction) when the electrode assembly (500) is viewed from above. If the total current collector (300) exceeds the above range, the space occupied by the current collector (300) in the width direction (y-axis direction) may be large, which may impose many restrictions on the placement of the vent portion (50). The vent section (50) is placed in an empty space where electrode tabs, current collectors, etc. are not located in the vertical direction, that is, the vent section (50) is placed in a position where it does not overlap with electrode tabs, current collectors, etc. in the vertical direction. If the above range is exceeded, the empty space is reduced, and restrictions may arise on the placement of the vent section (50).

[0119] Accordingly, as in the present embodiment, when the ratio occupied by the entire current collection member (300) satisfies the above range, the position of the vent portion (50) can be freely selected and the direction of the vent portion (50) can be freely arranged. Here, the direction of the vent portion (50) refers to the direction in which the long side of the vent portion (50) faces, and the vent portion (50) may be arranged in the width direction (y-axis direction), i.e., horizontally, or in the thickness direction (x-axis direction), i.e., vertically.

[0120] In this embodiment, the entire first current collector (310) is a single flat plate-shaped member, and the flatness of the first current collector (310) may be 0.05 mm to 2 mm. Here, flatness may be the same term as flatness. Flatness indicates the degree of flatness of the first current collector (310), and the smaller the value, the flatter it is. If the flatness of the first current collector (310) exceeds 2, a part of the first current collector (310) may come into contact with the upper surface of the electrode assembly (500) located below, and a short circuit may occur. Therefore, if the flatness of the first current collector (310) is within the corresponding range, a short circuit with the electrode assembly (500) can be prevented even if the first electrode tab bundle (11a, 11b, 11c) is coupled to the upper surface of the first current collector (310).

[0121] The planar view of the first current collector (310) may be a geometric tolerance that specifies that all points of the main support plate (311) and the branches (313, 315) are located between two parallel planes separated by a distance corresponding to a specified flatness (in mm).

[0122] For example, if the flatness is 0.1, this may mean that every point is within a zone defined by two parallel planes with a gap of 0.1 mm. In other words, it may mean that any point on the surface must be able to pass through a narrow 0.1 mm gap between two perfectly flat parallel plates without touching the plates.

[0123] For example, flatness can be measured using a precision-machined surface plate on which a current collector is placed and a feeler gauge for measuring flatness. Additionally, one or more of a dial indicator method, a three-dimensional measuring machine (CMM), an optical interferometer, and / or laser scanning may be used for the specified flatness measurement.

[0124] Meanwhile, the second current collector (330) may have the same shape as the first current collector (310). In this embodiment, the first current collector (310) and the second current collector (330) may be arranged symmetrically on the electrode assembly (500) with respect to the thickness direction (x-axis direction).

[0125] The second current collector (330) may include a main support plate (331) and a plurality of branches (333, 335). The main support plate (331) may support the second connection terminal (337) as a flat plate-shaped member. The second connection terminal (337) is located on the upper surface of the main support plate (331), and the second connection terminal (337) may be electrically connected to the second external terminal (24) coupled to the cap plate (21). At this time, the second connection terminal (337) may have a cylindrical shape.

[0126] A first branch (331) and a second branch (335) may be formed extending along the width direction (y-axis direction) on the side of the flat main support plate (331). The first branch (331) and the second branch (335) may be spaced apart from each other along the thickness direction (x-axis direction).

[0127] Similar to the first current collector (310), the width of the first branch (333) and the width of the second branch (335) of the second current collector (330) may differ from each other. Specifically, the width of the first branch (333) may be greater than the width of the second branch (335). Accordingly, two negative electrode tab bundles, namely the first negative electrode tab bundle (12a) and the second negative electrode tab bundle (12b), may be combined on the upper surface of the first branch (331) of the second current collector (330). Additionally, one negative electrode tab bundle, the first negative electrode tab bundle (12c), may be combined on the upper surface of the second branch (335) of the second current collector (330).

[0128] In this embodiment, the width of the first branch (333) of the second current collector (330), the width of the second branch (335), and the distance between the first branch (333) and the second branch (335) may be the same as that of the first current collector.

[0129] As illustrated in FIG. 4, the branches (313, 315) of the first current collector (310) and the branches (333, 335) of the second current collector (330) can be extended toward the center of the electrode assembly (500) along the width direction (y-axis direction). That is, the ends of the branches (313, 315) of the first current collector (310) and the ends of the branches (333, 335) of the second current collector (330) can be arranged to face each other.

[0130] The first connection terminal (317) of the first current collector (310) and the second connection terminal (337) of the second current collector (330) may each be positioned adjacent to both ends in the width direction (y-axis direction) of the electrode assembly (500). The first connection terminal (317) may be positioned adjacent to the left end of the electrode assembly (500), and the second connection terminal (337) may be positioned adjacent to the right end of the electrode assembly (500).

[0131] Referring to FIGS. 8 and 9, the first electrode tab bundle (11a) of the first electrode assembly (510) is formed by fixing the ends of the anode's non-positive portions protruding from the upper part of the first electrode assembly (510) together by a first welding. Before being coupled to the upper surface of the first current collector (310), the anode's non-positive portions are gathered into the center of the first electrode assembly (510) using a tab guide (not shown), and the ends of the gathered anode's non-positive portions are fixed by a first welding. A first welding area (PW1) may be formed at the end of the first electrode tab bundle (11a) of the anode by the first welding.

[0132] At this time, the first weld can be formed long along the width direction (y-axis direction). At this time, the first weld can have various shapes, such as a straight shape, a spiral shape, or a dot shape.

[0133] The first welding is a welding method to prevent the ends of the first electrode tab bundle (11a) from separating from each other while the first electrode tab bundle (11a) is bent and fixed onto the first current collector (310). The first welding may correspond to a pre-welding method that fixes only the ends of the first electrode tab bundle (11a) to each other. At this time, the first welding may be performed using ultrasonic welding or laser welding. Preferably, the first welding may be performed using ultrasonic welding.

[0134] Likewise, the first electrode tab bundle (11b) of the first electrode assembly (530) and the first electrode tab bundle (11c) of the first electrode assembly (550) can also form bundles by joining the ends of the unpaired portions of the anode in the same way. Additionally, the same first welding area (PW1) can be formed at the ends of the first electrode tab bundles (11b, 11c) of the anode by the first welding.

[0135] Additionally, the second electrode tab bundle (12a, 12b, 12c) of the first electrode assembly (510) is also formed by fixing the ends of the unpaired portions of the cathode to each other by the first welding. The second electrode tab bundle (12a, 12b, 12c) can be formed in the same way as the first electrode tab bundle (11a, 11b, 11c). At this time, a first welding area (PW2) can be formed at the end of the second electrode tab bundle (12a, 12b, 12c) of the cathode by the first welding.

[0136] Referring again to FIGS. 4 to 7, the first electrode tab bundles (11a, 11b, 11c) of the electrode assembly (500) can be arranged in a line along the thickness direction (x-axis direction). That is, the first electrode tab bundles (11a, 11b, 11c) can be arranged overlapping each other when viewed in the thickness direction (x-axis direction). All of the first electrode tab bundles (11a, 11b, 11c) can be formed protruding from the side end at the same position of the anode (11). In this embodiment, the second electrode tab bundles (12a, 12b, 12c) of the electrode assembly (500) have the same structure as the first electrode tab bundles (11a, 11b, 11c), so a detailed description thereof will be omitted.

[0137] Accordingly, the ends of the first electrode tab bundles (11a, 11b, 11c) can be arranged in a line along the thickness direction (x-axis direction) and coupled to the upper surface of the first current collector (310). The ends of the first electrode tab bundles (11a, 11b, 11c) are bent and coupled to the upper surface of the first current collector (310), and the first welding service (PW1) formed at the ends of the first electrode tab bundles (11a, 11b, 11c) can be located on the upper surface of the first current collector (310).

[0138] The upper end of the first electrode tab bundle (11a) and the upper end of the first electrode tab bundle (11b) may face each other and be located on the upper surface of the first branch (313) of the first current collector (310). Meanwhile, the upper end of the first electrode tab bundle (11c) may be located on the upper surface of the second branch (315) of the first current collector (310). By doing so, the first welding area (PW1) of the first electrode tab bundle (11a), the first welding area (PW1) of the first electrode tab bundle (11b), and the first welding area (PW1) of the first electrode tab bundle (11c) may be arranged in a line and located on the first current collector (310).

[0139] In FIG. 5, the first electrode tab bundle (11a) can be folded from top to bottom of the electrode assembly (500) and coupled to the upper surface of the first branch (313), and the first electrode tab bundle (11b) can be folded from bottom to top of the electrode assembly (500) and coupled to the upper surface of the first branch (313). That is, the first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be folded in directions facing each other and coupled to the upper surface of the first branch (313).

[0140] Meanwhile, the first electrode tab bundle (11c) may be folded from bottom to top of the electrode assembly (500) and coupled to the upper surface of the second branch (315). However, the first electrode tab bundle (11c) may also be folded from top to bottom of the electrode assembly (500) and coupled to the upper surface of the second branch (315).

[0141] Accordingly, in this embodiment, the first electrode tab bundle (11b) and the first electrode tab bundle (11c) are both bent from bottom to top of the electrode assembly (500), whereas the first electrode tab bundle (11a) can be bent from top to bottom of the electrode assembly (500) in the opposite way to the first electrode tab bundle (11b) and the first electrode tab bundle (11c).

[0142] In this embodiment, the end of the first electrode tab bundle (11a) can be joined to the first branch (313) by a second welding. Specifically, the end of the first electrode tab bundle (11a) can be bent and brought into close contact with the upper surface of the first branch (313), and then the second welding can be performed on the end of the first electrode tab bundle (11a) so that the end of the first electrode tab bundle (11a) can be joined to the first branch (313).

[0143] A second weld can be performed on the first welding area (PW1) of the first electrode tab bundle (11a) so that the end of the first electrode tab bundle (11a) can be joined to the upper surface of the first current collector (310). The second weld can be formed long along the extension direction of the first branch (313), that is, the width direction (y-axis direction). At this time, the second weld can have various shapes, such as a straight shape, a spiral shape, or a dot shape.

[0144] The second welding is a welding that fixes the end of the first electrode tab bundle (11a) to the upper surface of the first current collector (310), and the second welding may correspond to a main welding that fixes and joins the first electrode tab bundle (11a) onto the first current collector (310). At this time, laser welding or ultrasonic welding, etc., may be applied for the second welding. Preferably, laser welding may be applied for the second welding.

[0145] Specifically, in this embodiment, the second welding area (MW1) formed at the end of the first electrode tab bundle (11a) by the second welding may overlap at least partially with the first welding area (PW1) formed at the end of the first electrode tab bundle (11a). Preferably, the entire second welding area (MW1) may overlap with the first welding area (PW1). That is, the entire second welding area (MW1) may be located within the first welding area (PW1).

[0146] As shown in FIG. 5, the area of ​​the first welding area (PW1) can be formed larger than the area of ​​the second welding area (MW1). That is, the welding area formed by the first welding can be formed larger than the welding area formed by the second welding.

[0147] In this embodiment, the area of ​​the first welding area (PW1) may be 1.1 to 5 times the area of ​​the second welding area (MW1). Since the ends of the first electrode tab bundle (11a) are joined together by the first welding before the second welding is performed, even if the area of ​​the second welding area (MW1) is smaller than the area of ​​the first welding area (PW1), the ends of the first electrode tab bundle (11a) can be firmly joined to the upper surface of the first current collector (310). That is, since the ends of the first electrode tab bundle (11a) are firmly fixed in advance by the first welding, even if only a part of the ends of the first electrode tab bundle (11a) is fixed on the first current collector (310) by the second welding, the ends of the first electrode tab bundle (11a) can be firmly fixed to the upper surface of the first current collector (310).

[0148] Meanwhile, the length (IT1) of the first welding area (PW1) in the width direction (y-axis direction) may be greater than the length (M1) of the second welding area (MW1). Additionally, the thickness (W1) of the first welding area (PW1) in the thickness direction (x-axis direction) may be greater than the thickness (W2) of the second welding area (MW1). Accordingly, as described above, the area of ​​the first welding area (PW1) can be formed to be larger than the area of ​​the second welding area (MW1).

[0149] Referring to FIG. 7, the ends of the first electrode tab bundles (11a, 11b, 11c) are bent and fixed to the upper surface of the first current collector (310), and a portion of the remaining parts excluding the ends of the first electrode tab bundles (11a, 11b, 11c) can be maintained in a bent state toward the upper surface of the electrode assembly (500) by means of insulating tapes (T1, T2, T3). At this time, the insulating tapes (T1, T2, T3) can be positioned between the current collector (300) and the upper surface of the electrode assembly (500).

[0150] A portion of the first electrode tab bundle (11a) adjacent to the upper surface of the first electrode assembly (510) may be folded and fixed toward the upper surface of the first electrode assembly (510) by an insulating tape (T1). A portion of the first electrode tab bundle (11b) adjacent to the upper surface of the second electrode assembly (530) may be folded and fixed toward the upper surface of the second electrode assembly (530) by an insulating tape (T2). A portion of the first electrode tab bundle (11c) adjacent to the upper surface of the third electrode assembly (550) may be folded and fixed toward the upper surface of the third electrode assembly (550) by an insulating tape (T3).

[0151]

[0152] Hereinafter, a secondary battery according to the second embodiment of the present invention will be described.

[0153] FIG. 10 is a perspective view illustrating a current collector according to a second embodiment of the present invention, and FIG. 11 is a cross-sectional view illustrating the state in which the current collector of FIG. 10 and the electrode assembly are combined.

[0154] Referring to FIGS. 10 and 11, the secondary battery according to the second embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the insulating holder (CH), so a redundant description of the same configuration is omitted.

[0155] In this embodiment, an insulating holder (CH) may be disposed on the lower surface of the first current collector (310). The insulating holder (CH) can support and fix the first current collector (310) on the lower surface of the first current collector (310). In this embodiment, the insulating holder (CH) coupled to the lower surface of the second current collector (330) has the same structure as the insulating holder (CH) of the first current collector (310), so a detailed description thereof will be omitted.

[0156] The insulating holder (CH) can prevent the shape of the first current collector (310) from being deformed or damaged during the welding process of the first electrode tab bundle (11a, 11b, 11c) and the first current collector (310) or while the first current collector (310) is located inside the case (100).

[0157] When the first branch (313) and the second branch (315) of the first current collector (310) are deformed vertically, the first branch (313) and the second branch (315) come into contact with the upper surface of the electrode assembly (500), and the electrode assembly (500) may be damaged or short-circuited. Additionally, when the first branch (313) and the second branch (315) are deformed horizontally, the gap between the first branch (313) and the second branch (315) changes, and the side of the first electrode tab bundle (11a, 11b, 11c) coupled to the upper surface of the first branch (313) and the second branch (315) may be damaged or cut. Accordingly, in this embodiment, the insulating holder (CH) supports and fixes the first current collector (310), thereby preventing the electrode assembly (500) or the first electrode tab bundle (11a, 11b, 11c) from being damaged or short-circuited.

[0158] The insulating holder (CH) may have a shape corresponding to the shape of the first current collector (310). At this time, the insulating holder (CH) may accommodate the first current collector (310) inside. The insulating holder (CH) may support the first current collector (310) by wrapping around the lower surface and side surface of the accommodated first current collector (310). To prevent the first current collector (310) accommodated inside from coming loose, a plurality of hooks (CH_H) may be arranged on the side surface of the insulating holder (CH). The first current collector (310) may be fixed inside the insulating holder (CH) by the plurality of hooks (CH_H).

[0159] A cut groove (CH_G) with a portion of the side cut may be formed on the side of the insulating holder (CH) so that the first electrode tab bundle (11a, 11b, 11c) protruding from the electrode assembly (500) is bent and contacts the upper surface of the first current collector (310). When the first electrode tab bundle (11a, 11b, 11c) protruding from the electrode assembly (500) is bent and the bent first electrode tab bundle (11a, 11b, 11c) contacts the upper surface of the first current collector (310), the first electrode tab bundle (11a, 11b, 11c) may not be interfered with by the side of the insulating holder (CH) by means of the cut groove (CH_G).

[0160] A portion of the side of the first current collector (310) housed within the insulating holder (CH) may be exposed by the cut groove (CH_G). The contact area between the first current collector (310) and the first electrode tab bundle (11a, 11b, 11c) may be increased by the cut groove (CH_G).

[0161]

[0162] A secondary battery according to the third embodiment of the present invention will be described below.

[0163] FIG. 12 is a plan view illustrating a state in which an electrode tab bundle is coupled to a current collector member according to a third embodiment of the present invention, and FIG. 13 is a side view of an electrode having an electrode tab bundle formed thereon according to a third embodiment of the present invention.

[0164] Referring to FIGS. 12 and 13, the secondary battery according to the third embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the first electrode tab bundle (11a, 11b, 11c), so a redundant description of the same configuration is omitted.

[0165] In this embodiment, the first welding area (PW1) may be formed at a position spaced apart from the upper side end of the first electrode tab bundle (11a, 11b, 11c). In the first embodiment described above, the first welding area (PW1) is formed at the upper side end of the first electrode tab bundle (11a, 11b, 11c), so that only the first welding area (PW1) is located at the side end of the first electrode tab bundle (11a, 11b, 11c).

[0166] A first welding area (PW1) is located at a position spaced apart from the upper side end of the first electrode tab bundle (11a, 11b, 11c), and only an unwelded, bare portion is located at the side end. That is, only an unwelded, bare portion is located between the upper side end of the first electrode tab bundle (11a, 11b, 11c) and the first welding area (PW1).

[0167] As illustrated in FIG. 12, on the upper surface of the first branch (313) of the first current collector (310), not only the first welding area (PW1) but also the unwelded portion of the first electrode tab bundle (11a) and the unwelded portion of the first electrode tab bundle (11b) may be located. Additionally, on the upper surface of the first branch (313), the unwelded portion of the first electrode tab bundle (11a) and the unwelded portion of the first electrode tab bundle (11b) are arranged side by side with each other. On the upper surface of the second branch (315), the unwelded portion of the first electrode tab bundle (11c) and the first welding area (PW1) may be located.

[0168] As the thickness of the electrode assembly (500) increases, the length of the unoccupied portion becomes longer to form the first electrode tab bundle (11a, 11b, 11c). In order to maintain a constant distance between the upper surface of the electrode assembly (500) and the current collector (300), as the length of the unoccupied portion increases, the first welding area (PW1) can be spaced apart from the upper side end of the first electrode tab bundle (11a, 11b, 11c).

[0169]

[0170] Hereinafter, a secondary battery according to the fourth embodiment of the present invention will be described.

[0171] FIG. 14 is a plan view illustrating a state in which a current collecting member is coupled to a plurality of electrode assemblies according to a fourth embodiment of the present invention.

[0172] Referring to FIG. 14, the secondary battery according to the fourth embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the current collector (300), so a redundant description of the same configuration is omitted.

[0173] In this embodiment, the first current collector (310) and the second current collector (330) may be arranged symmetrically around a virtual center point on the upper surface of the electrode assembly (500).

[0174] In the first embodiment described above, the first current collector (310) and the second current collector (330) may be arranged symmetrically with respect to each other around an axis parallel to the thickness direction (x-axis direction). In the present embodiment, however, the first current collector (310) and the second current collector (330) may be arranged point-symmetrically around a virtual center point on the upper surface of the electrode assembly (500).

[0175] That is, if the first current collector (310) is rotated 180 degrees, it may be in a form that overlaps with the second current collector (330). Or, if the second current collector (330) is rotated 180 degrees, it may be in a form that overlaps with the first current collector (310).

[0176]

[0177] Hereinafter, a secondary battery according to the fifth embodiment of the present invention will be described.

[0178] FIG. 15 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the fifth embodiment of the present invention.

[0179] Referring to FIG. 15, the secondary battery according to the fifth embodiment is formed with the same structure as the secondary battery according to the first embodiment described above, except for the current collector (300) and the electrode assembly (500), so a redundant description of the same configuration is omitted. In addition, since the second current collector (330) has the same structure as the first current collector (310), a detailed description is omitted.

[0180] In this embodiment, the electrode assembly (500) may include two electrode assemblies: a first electrode assembly (510) and a second electrode assembly (520).

[0181] An equal number of first electrode tab bundles (11a, 11b) can be connected to the first branch (313) and the second branch (315) of the first current collector (310). One first electrode tab bundle can be connected to each of the first branch (313) and the second branch (315). A first electrode tab bundle (11a) can be connected to the upper surface of the first branch (313), and a first electrode tab bundle (11b) can be connected to the upper surface of the second branch (315).

[0182] At this time, the first branch (313) and the second branch (315) may have the same width. Accordingly, the area of ​​the first electrode tab bundle (11a) coupled to the upper surface of the first branch (313) and the area of ​​the first electrode tab bundle (11b) coupled to the upper surface of the second branch (315) may be the same. Therefore, the first current collector (310) may be arranged symmetrically with respect to an axis parallel to the width direction (y-axis direction).

[0183] In FIG. 15, the first electrode tab bundle (11a) can be folded from top to bottom of the electrode assembly (500) and coupled to the upper surface of the first branch (313), and the first electrode tab bundle (11b) can be folded from bottom to top of the electrode assembly (500) and coupled to the upper surface of the second branch (315). That is, the first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be folded in a direction facing each other and coupled to the upper surfaces of the first branch (313) and the second branch (315).

[0184]

[0185] Hereinafter, a secondary battery according to the 6th embodiment of the present invention will be described.

[0186] FIG. 16 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the 6th embodiment of the present invention.

[0187] Referring to FIG. 16, the secondary battery according to the sixth embodiment is formed with the same structure as the secondary battery according to the first embodiment described above, except for the current collector (300) and the electrode assembly (500), so a redundant description of the same configuration is omitted. In addition, since the second current collector (330) has the same structure as the first current collector (310), a detailed description is omitted.

[0188] In this embodiment, the electrode assembly (500) may include a first electrode assembly (510), a second electrode assembly (520), a third electrode assembly (530), and a fourth electrode assembly (540), i.e., four electrode assemblies (500). The four electrode assemblies may be stacked on top of each other and arranged in a row.

[0189] An equal number of first electrode tab bundles (11a, 11b, 11c, 11d) can be connected to the first branch (313) and the second branch (315) of the first current collector (310). Two first electrode tab bundles (11a, 11b) can be connected to the first branch (313), and two first electrode tab bundles (11c, 11d) can be connected to the second branch (315).

[0190] On the upper surface of the first branch (313), the first electrode tab bundle (11a) can be folded from top to bottom and coupled to the upper surface of the first branch (313), and the first electrode tab bundle (11b) can be folded from bottom to top of the electrode assembly (500) and coupled to the upper surface of the first branch (313). That is, the first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be folded in directions facing each other and coupled to the upper surface of the first branch (313).

[0191] On the upper surface of the second branch (315), the first electrode tab bundle (11c) can be folded from top to bottom and coupled to the upper surface of the second branch (315), and the first electrode tab bundle (11d) can be folded from bottom to top and coupled to the upper surface of the second branch (315). That is, the first electrode tab bundle (11c) and the first electrode tab bundle (11d) can be folded in directions facing each other and coupled to the upper surface of the second branch (315).

[0192] Additionally, the first electrode tab bundles (11a, 11b, 11c, 11d) may be arranged in a line along the thickness direction (x-axis direction). That is, the first electrode tab bundles (11a, 11b, 11c, 11d) may be arranged overlapping each other when viewed in the thickness direction (x-axis direction).

[0193] At this time, the first branch (313) and the second branch (315) may have the same width. Accordingly, the area of ​​the first electrode tab bundle (11a, 11b) coupled to the upper surface of the first branch (313) and the area of ​​the first electrode tab bundle (11c, 11d) coupled to the upper surface of the second branch (315) may be the same. Therefore, the first current collector (310) may be arranged symmetrically with respect to an axis parallel to the width direction (y-axis direction).

[0194]

[0195] Hereinafter, a secondary battery according to the seventh embodiment of the present invention will be described.

[0196] FIG. 17 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the seventh embodiment of the present invention.

[0197] Referring to FIG. 17, the secondary battery according to the seventh embodiment is formed with the same structure as the secondary battery according to the sixth embodiment described above, except for the current collector (300) and the electrode assembly (500), so a redundant description of the same configuration is omitted. In addition, since the second current collector (330) has the same structure as the first current collector (310), a detailed description is omitted.

[0198] In this embodiment, the electrode assembly (500) may include a first electrode assembly (510), a second electrode assembly (520), a third electrode assembly (530), a fourth electrode assembly (540), and a fifth electrode assembly (550), i.e., five electrode assemblies (500). The five electrode assemblies may be stacked on top of each other and arranged in a straight line.

[0199] The first current collector (310) may include a first branch (313), a second branch (315), and a third branch (319). The widths of the first branch (313) and the second branch (315) are equal to each other, and the third branch (319) may be formed to be smaller than the widths of the first branch (313) and the second branch (315).

[0200] Two first electrode tab bundles may be connected to each of the first branch (313) and the second branch (315), and one first electrode tab bundle may be connected to the third branch (319). First electrode tab bundles (11a, 11b) may be connected to the upper surface of the first branch (313), and first electrode tab bundles (11c, 11d) may be connected to the upper surface of the second branch (315). First electrode tab bundle (11e) may be connected to the upper surface of the third branch (319).

[0201] On the upper surface of the first branch (313), the first electrode tab bundle (11a) can be folded from top to bottom and coupled to the upper surface of the first branch (313), and the first electrode tab bundle (11b) can be folded from bottom to top of the electrode assembly (500) and coupled to the upper surface of the first branch (313). That is, the first electrode tab bundle (11a) and the first electrode tab bundle (11b) can be folded in directions facing each other and coupled to the upper surface of the first branch (313).

[0202] On the upper surface of the second branch (315), the first electrode tab bundle (11c) can be folded from top to bottom and coupled to the upper surface of the second branch (315), and the first electrode tab bundle (11d) can be folded from bottom to top and coupled to the upper surface of the second branch (315). That is, the first electrode tab bundle (11c) and the first electrode tab bundle (11d) can be folded in directions facing each other and coupled to the upper surface of the second branch (315).

[0203] On the upper surface of the third branch (319), the first electrode tab bundle (11e) can be folded from bottom to top and coupled to the upper surface of the third branch (319). However, the first electrode tab bundle (11e) is not limited thereto and can be folded from top to bottom and coupled to the upper surface of the third branch (319).

[0204] Additionally, the first electrode tab bundles (11a, 11b, 11c, 11d, 11e) may be arranged in a line along the thickness direction (x-axis direction). That is, the first electrode tab bundles (11a, 11b, 11c, 11d, 11e) may be arranged overlapping each other when viewed in the thickness direction (x-axis direction).

[0205]

[0206] Hereinafter, a secondary battery according to the eighth embodiment of the present invention will be described.

[0207] FIG. 18 is a plan view partially illustrating a state in which a current collector is coupled to a plurality of electrode assemblies according to the eighth embodiment of the present invention.

[0208] Referring to FIG. 18, the secondary battery according to the eighth embodiment is formed with the same structure as the secondary battery according to the seventh embodiment described above, except for the current collector (300) and the electrode assembly (500), so a redundant description of the same configuration is omitted. In addition, since the second current collector (330) has the same structure as the first current collector (310), a detailed description is omitted.

[0209] In this embodiment, the electrode assembly (500) may include a first electrode assembly (510), a second electrode assembly (520), a third electrode assembly (530), a fourth electrode assembly (540), a fifth electrode assembly (550), and a sixth electrode assembly (560), i.e., six electrode assemblies (500). The six electrode assemblies may be stacked on top of each other and arranged in a straight line.

[0210] An equal number of first electrode tab bundles (11a, 11b, 11c, 11d, 11e, 11f) may be connected to the first branch (313), second branch (315), and third branch (319) of the first current collector (310). Two first electrode tab bundles may be connected to each of the first branch (313) to the third branch (319).

[0211] A first electrode tab bundle (11e, 11f) can be attached to the upper surface of the third branch (319). The first electrode tab bundle (11e) can be folded from top to bottom and attached to the upper surface of the third branch (319), and the first electrode tab bundle (11f) can be folded from bottom to top and attached to the upper surface of the third branch (319).

[0212] At this time, the first branch (313), the second branch (315), and the third branch (319) may have the same width. Accordingly, the area of ​​the first electrode tab bundle (11a, 11b) coupled to the upper surface of the first branch (313), the area of ​​the first electrode tab bundle (11c, 11d) coupled to the upper surface of the second branch (315), and the area of ​​the first electrode tab bundle (11e, 11f) coupled to the upper surface of the third branch (319) may be the same. Therefore, the first current collector (310) may be arranged symmetrically with respect to an axis parallel to the width direction (y-axis direction).

[0213]

[0214] Hereinafter, a secondary battery according to the ninth embodiment of the present invention will be described.

[0215] FIG. 19 is a perspective view of a vent portion viewed from below according to the ninth embodiment of the present invention.

[0216] Referring to FIG. 19, the secondary battery according to the ninth embodiment has the same structure as the secondary battery according to the first embodiment described above, except for the vent portion (50), so a redundant description of the same configuration is omitted.

[0217] In this embodiment, the secondary battery (10) may be a rectangular battery having a case (100) in the shape of a rectangular prism, and the vent portion (50) may be fixed to the bottom (100a) of the case (100). The bottom (100a) of the case (100) may be formed integrally with the case (100) or fixed to the case (100) by welding or the like.

[0218] An exhaust hole for discharging gas is formed in the bottom (100a) of the case (100), a vent portion (50) is inserted on the lower outer side of the exhaust hole, and a vent protection film (60) may be placed on the lower outer side of the vent portion (50).

[0219] The vent portion (50) is formed in the shape of a plate and can be fixed to the case (100) by welding. The vent portion (50) can extend long in the width direction (y-axis direction) of the bottom of the case.

[0220] The vent portion (50) may include two side notches (52, 53) and a connecting notch (51) connecting the side notches (52, 53). Since the connecting notch (51) and the side notches (52, 53) are formed with the same structure as the connecting notch and side notches according to the first embodiment described above, a redundant description thereof is omitted.

[0221] Meanwhile, a vent protection film (60) may be installed at the bottom of the vent portion (50). The vent protection film (60) may be made of a flexible film, and a connection hole for discharging pressure may be formed in the vent protection film (60).

[0222] As described above, according to the ninth embodiment, a vent portion (50) is formed on the bottom (100a) of the case (100), so that the electrolyte can also be discharged when the vent portion (50) is opened.

[0223]

[0224] Hereinafter, a secondary battery according to the 10th embodiment of the present invention will be described.

[0225] FIG. 20 is a perspective view illustrating a secondary battery according to the 10th embodiment of the present invention, and FIG. 21 is a top view of the secondary battery of FIG. 20.

[0226] Referring to FIGS. 20 and 21, the secondary battery according to the 10th embodiment has the same structure as the secondary battery according to the 1st embodiment described above, except for the vent portion (50), so a redundant description of the same configuration is omitted.

[0227] In this embodiment, the vent portion (50) may extend in the thickness direction (x-axis direction). The vent portion (50) is formed in a shape that extends in the thickness direction (x-axis direction) and may have a shape such as a rectangle, an oblong, or a rounded rectangle. In the first embodiment described above, the vent portion (50) is formed extending in the width direction (y-axis direction), but in this embodiment, it is formed extending in the thickness direction (x-axis direction) that intersects the direction of the vent portion (50) of the first embodiment.

[0228] The vent portion (50) can be fixed to the cap plate (21) by welding. The vent portion (50) can be fixed to the lower surface of the cap plate (21), but can also be fixed to the upper surface of the cap plate (21).

[0229] In this embodiment, as a plurality of electrode assemblies (500) are stacked and the thickness of the cap plate (21) increases (parallel to the direction in the thickness direction (x-axis direction)), the vent portion (50) can be positioned in the thickness direction (x-axis direction). Accordingly, when gas is discharged, the vent portion (50) is not interfered with by the first current collector (310) and the second current collector (330) located at the bottom, so the vent portion (50) can smoothly discharge gas.

[0230]

[0231] Hereinafter, a secondary battery according to the 11th embodiment of the present invention will be described.

[0232] FIG. 22 is a perspective view of a vent portion viewed from below according to the 11th embodiment of the present invention.

[0233] Referring to FIG. 22, the secondary battery according to the 11th embodiment has the same structure as the secondary battery according to the 10th embodiment described above, except for the vent portion (50), so a redundant description of the same configuration is omitted.

[0234] In this embodiment, the secondary battery (10) may be a rectangular battery having a case (100) in the shape of a rectangular prism, and the vent portion (50) may be fixed to the bottom (100a) of the case (100). The bottom (100a) of the case (100) may be formed integrally with the case (100) or fixed to the case (100) by welding or the like.

[0235] An exhaust hole for discharging gas is formed in the bottom (100a) of the case (100), a vent portion (50) is inserted on the lower outer side of the exhaust hole, and a vent protection film (60) may be placed on the lower outer side of the vent portion (50).

[0236] The vent portion (50) is formed in the shape of a plate and can be fixed to the case (100) by welding.

[0237] The vent portion (50) can be extended in the thickness direction (x-axis direction). The vent portion (50) is formed in a shape that is extended in the thickness direction (x-axis direction) and can have a shape such as a rectangle, an oblong, or a rounded rectangle.

[0238] Meanwhile, a vent protection film (60) may be installed at the bottom of the vent portion (50). The vent protection film (60) may be made of a flexible film, and a connection hole for discharging pressure may be formed in the vent protection film (60).

[0239] As described above, according to the 11th embodiment, a vent portion (50) is formed on the bottom (100a) of the case (100), so that the electrolyte can also be discharged when the vent portion (50) is opened.

[0240]

[0241] 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.

Claims

1. Case; A plurality of electrode assemblies, each comprising an electrode and housed in the above case; Electrode tab bundles formed on each electrode of the plurality of electrode assemblies; A current collecting member coupled to the electrode tab bundle of the plurality of electrode assemblies; A cap assembly that seals the above case and has an external terminal connected to the above current collector located thereon; comprising The above current collecting member is, A main support plate on which a connection terminal connected to the above external terminal is located, and A secondary battery comprising a plurality of branches formed extending along the width direction of the electrode assembly on the side of the main support plate and to which the electrode tab bundle is connected.

2. In Paragraph 1, A secondary battery in which the ends of the electrode tab bundle are fixedly joined to each other by a first welding.

3. In Paragraph 2, A secondary battery in which the end of the electrode tab bundle is fixed over the plurality of branches by a second welding.

4. In Paragraph 3, A secondary battery in which the second weld area formed at the end by the second weld overlaps at least partially with the first weld area formed at the end by the first weld.

5. In Paragraph 4, The second welding area is a secondary battery located within the first welding area.

6. In Paragraph 4, The above first welding area is a secondary battery located in contact with the side end of the electrode tab bundle.

7. In Paragraph 4, A secondary battery in which the first welding area is located spaced apart from the side end of the electrode tab bundle.

8. In Paragraph 3, A secondary battery, wherein the area of ​​the first weld region formed at the end by the first weld is 1.1 to 5 times the area of ​​the second weld region formed at the end by the second weld.

9. In Paragraph 8, A secondary battery in which the length of the first welded area in the width direction is greater than the length of the second welded area.

10. In Paragraph 1, The above plurality of branches are, A secondary battery comprising a first branch and a second branch spaced apart from each other in the thickness direction of the electrode assembly intersecting the width direction.

11. In Paragraph 10, A secondary battery in which a different number of electrode tab bundles are coupled to the first branch and the second branch.

12. In Paragraph 11, A secondary battery in which two electrode tab bundles are connected to the first branch and one electrode tab bundle is connected to the second branch.

13. In Paragraph 12, A secondary battery in which the two electrode tab bundles and the one electrode tab bundle are arranged in a line along the thickness direction.

14. In Paragraph 13, The two electrode tab bundles are bent to face each other along the thickness direction and joined to the first branch, and A secondary battery in which one of the electrode tab bundles is bent in the same direction as the adjacent electrode tab bundle among the two electrode tab bundles and coupled to the second branch.

15. In Paragraph 14, The plurality of electrode assemblies includes three electrode assemblies arranged parallel to each other along the thickness direction, A secondary battery having one electrode tab bundle located in each of the three electrode assemblies above.

16. In Paragraph 12, A secondary battery in which the first width of the first branch in the thickness direction is greater than the second width of the second branch.

17. In Paragraph 16, A secondary battery in which the first width of the first branch and the second width of the second branch satisfy the following formula 1. [Formula 1] 1 / 3 * C1 ≤ C2 ≤ 1 / 1.5 * C1 Here, C1 is the first width and C2 is the second width.

18. In Paragraph 17, A secondary battery in which the first area of ​​the first branch and the second area of ​​the second branch satisfy the following Equation 2. [Equation 2] 1 / 3 * S1 ≤ S2 ≤ 1 / 1.5 * S1 Here, S1 is the first area and S2 is the second area.

19. In Paragraph 16, A secondary battery in which the separation distance between the first branch and the second branch satisfies the following Equation 3. [Equation 3] 1 / 2 * C2 ≤ CD ≤ C1 Here, C1 is the first width, C2 is the second width, and CD is the separation distance between the first branch and the second branch.

20. In Paragraph 10, The above electrode tab bundle is coupled to the upper surface of the first branch and the second branch, a secondary battery.

21. In Paragraph 10, A secondary battery in which the same number of electrode tab bundles are coupled to the first branch and the second branch.

22. In Paragraph 1, The above connection terminal is a secondary battery positioned adjacent to the side end of the electrode assembly in the width direction.

23. In Paragraph 1, The above connection terminal is a cylindrical secondary battery.

24. In Paragraph 1, A secondary battery in which the main support plate and the plurality of branches form the same plane.

25. In Paragraph 24, A secondary battery in which the flatness of the main support plate and the plurality of branches is 0.05 mm to 2 mm.

26. In Paragraph 1, A secondary battery in which the total length of the current collector in the width direction is 0.5 to 0.75 times the length of the electrode assembly.

27. In Paragraph 1, A secondary battery in which an insulating holder supporting the current collector is coupled to the lower part of the current collector.

28. In Paragraph 1, At least a portion of the above electrode tab bundle is folded parallel to the upper surface of the electrode assembly by means of an insulating tape, and The above insulating tape is located between the above current collector and the above upper surface of the above electrode assembly, in a secondary battery.

29. In Paragraph 1, A secondary battery in which a first current collector and a second current collector, each connected to electrodes of different polarities, are symmetrical to each other with respect to an axis extending in the thickness direction of the electrode assembly that intersects the width direction.

30. In Paragraph 1, A secondary battery in which a first current collector and a second current collector, each connected to electrodes of different polarities, are point-symmetric with respect to the center point of the electrode assembly.

31. In Paragraph 1, It further includes a vent portion formed in the above case or the above cap assembly, and A secondary battery in which the long axis direction of the above-mentioned vent portion is parallel to or intersects the above-mentioned width direction.

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