Secondary battery electrode assembly and battery cell including the same

Abstract

The present invention relates to an electrode assembly for a secondary battery and a battery cell comprising the same, and more particularly, to an electrode assembly for a secondary battery and a battery cell comprising the same, the electrode assembly comprising: at least one positive electrode; the positive pole comprises a positive pole current collector and a positive pole connecting piece extending along one side direction of the positive pole current collector; the negative electrode comprises a negative electrode current collector and a negative electrode connecting piece which extends along one side direction of the negative electrode current collector; a separator interposed between the positive electrode and the negative electrode; a positive lead electrically connected to the positive tab; and a negative electrode lead electrically connected to the negative electrode tab, in which the positive electrode current collector has a first resin layer interposed between the pair of aluminum layers, and a first metal foil is interposed between the positive electrode tabs and between the positive electrode tab located at the outermost portion and the positive electrode lead.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 2023-0149455, filed on November 1, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a secondary battery electrode assembly and a battery cell including the secondary battery electrode assembly, and more particularly, to a secondary battery electrode assembly having a structure in which electrode tabs can be firmly connected and fixed to electrode leads, and each of the electrode tabs has a structure in which a resin layer is interposed between a pair of metal layers, and a battery cell including the secondary battery electrode assembly. Background Art

[0003] With the technological development of mobile devices and the increasing demand for them, secondary batteries capable of charging and discharging have been used as an energy source for various mobile devices. Secondary batteries have also attracted attention as an energy source for electric vehicles and hybrid electric vehicles, which exist as alternatives to existing gasoline and diesel vehicles that use fossil fuels.

[0004] According to the shape of the battery case, secondary batteries are classified into: cylindrical batteries in which the electrode assembly is installed in a cylindrical metal can; prismatic batteries in which the electrode assembly is installed in a prismatic metal can; and pouch batteries in which the electrode assembly is installed in a pouch-shaped case made of an aluminum laminate.

[0005] In particular, in the case of pouch secondary batteries, a plurality of positive electrodes each having a predetermined size and a plurality of negative electrodes each having a predetermined size are sequentially stacked with a separator interposed therebetween, and electrode tabs or a pair of electrode leads connected to the electrode tabs protrude outward from one side or opposite sides of the case.

[0006] Meanwhile, an aluminum current collector is generally used as a positive current collector to which a positive electrode active material is applied. However, due to various reasons, the aluminum current collector has been pointed out as a major ignition source, and thus research is underway to replace the aluminum current collector with a multi-layer current collector, such as a current collector having a structure in which a resin layer is interposed between two metal layers.

[0007] When using such a three-layer current collector, it is envisioned that safety can be improved because the thin metal layer has a large resistance in the case of a short circuit and can quickly cut off the current.

[0008] Figure 1 is a partial schematic view of a conventional secondary battery. As Figure 1 shown therein, the electrode assembly 10 has a structure in which a plurality of tabs 20 extend outward, and electrode leads 30 are interposed between the tabs 20 and are fixed to the tabs 20 by welding.

[0009] However, in the case of a three-layer current collector, since a resin layer is provided in the middle, it is difficult to connect the electrode tab to the electrode lead by a conventional welding method.

[0010] (Prior art document)

[0011] (Patent document 1) Korean Patent Application Publication No. 2022-0124358

[0012] (Patent document 2) Korean Patent Application Publication No. 2023-0020177 Summary of the Invention

[0013] Technical Problem

[0014] The present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary battery electrode assembly having a structure in which electrode current collectors can be firmly connected to each other, and a battery cell including the secondary battery electrode assembly, wherein each electrode current collector has a resin layer interposed between metal layers.

[0015] Another object of the present invention is to provide a secondary battery electrode assembly having a structure in which an electrode current collector and an electrode lead can be firmly connected to each other, and a battery cell including the secondary battery electrode assembly, wherein the electrode current collector has a resin layer interposed between metal layers.

[0016] Technical Solution

[0017] A secondary battery electrode assembly according to the present invention for achieving the above object includes: at least one positive electrode 100 including a positive current collector 110 and a positive tab 120 extending from the positive current collector 110 in one direction; at least one negative electrode 200 including a negative current collector 210 and a negative tab 220 extending from the negative current collector 210 in one direction; a separator 300 interposed between the positive electrode 100 and the negative electrode 200; a positive lead 400 electrically connected to the positive tab 120; and a negative lead 500 electrically connected to the negative tab 220, wherein the positive current collector 110 has a first resin layer 112 interposed between a pair of aluminum layers 111, and a first metal foil 600 is interposed between the positive tabs 120 and between the outermost positive tab 120 and the positive lead 400.

[0018] In addition, in the secondary battery electrode assembly according to the present invention, the first metal foil 600 may be positioned along the longitudinal edge of each positive tab among the positive tabs 120.

[0019] In addition, in the secondary battery electrode assembly according to the present invention, the first metal foil 600 may include a 1a metal foil 610 and a 1b metal foil 620, and the 1a metal foil and the 1b metal foil are respectively positioned along opposite edges in the longitudinal direction of each positive tab 120 in the positive tabs.

[0020] In addition, in the secondary battery electrode assembly according to the present invention, the first metal foil 600 may have a corrugated shape formed by bending a strip having a certain width and length, and the corrugated shape has repeating ridges and valleys.

[0021] In addition, in the secondary battery electrode assembly according to the present invention, the first metal foil 600 may contain aluminum.

[0022] In addition, in the secondary battery electrode assembly according to the present invention, the positive lead 400 may be fixed to the first metal foil 600 and the aluminum layer 111 by ultrasonic welding.

[0023] In addition, in the secondary battery electrode assembly according to the present invention, the first resin layer 112 may be made of polyethylene terephthalate (PET).

[0024] In addition, in the secondary battery electrode assembly according to the present invention, the negative current collector 21 may have a second resin layer 212 interposed between a pair of copper layers 211, and a second metal foil 700 may be interposed between the negative tabs 220 and between the outermost negative tab 220 and the negative lead 500.

[0025] In addition, in the secondary battery electrode assembly according to the present invention, the second metal foil 700 may be positioned along the edges in the longitudinal direction of each negative tab 220 in the negative tabs.

[0026] In addition, in the secondary battery electrode assembly according to the present invention, the second metal foil 700 may include a 2a metal foil 710 and a 2b metal foil 720, and the 2a metal foil and the 2b metal foil are respectively positioned along opposite edges in the longitudinal direction of each negative tab 220 in the negative tabs.

[0027] In addition, in the secondary battery electrode assembly according to the present invention, the second metal foil 700 may have a corrugated shape formed by bending a strip having a certain width and length, and the corrugated shape has repeating ridges and valleys.

[0028] In addition, in the secondary battery electrode assembly according to the present invention, the second metal foil 700 may contain copper, nickel-plated copper, or a nickel-copper alloy.

[0029] In addition, in the secondary battery electrode assembly according to the present invention, the negative lead 500 may be fixed to the second metal foil 700 and the copper layer 211 by ultrasonic welding.

[0030] In addition, in the secondary battery electrode assembly according to the present invention, the second resin layer 212 may be made of polyethylene terephthalate (PET).

[0031] In addition, the present invention provides a battery cell including the secondary battery electrode assembly.

[0032] Advantageous Effects

[0033] The secondary battery electrode assembly according to the present invention and the battery cell including the secondary battery electrode assembly have the following advantages: while a metal foil having a corrugated shape with repeated ridges and valleys formed by bending a tape is disposed along an edge in the longitudinal direction of the electrode tab, ultrasonic welding is performed, whereby the electrode tabs can be firmly fixed to each other.

[0034] In addition, the secondary battery electrode assembly according to the present invention and the battery cell including the secondary battery electrode assembly are advantageous in that ultrasonic welding is performed while a portion of the metal foil interposed between the electrode tabs overlaps with the electrode tab and the electrode lead between the electrode tab and the electrode lead, whereby the electrode tab can be firmly fixed to the electrode lead. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a partial schematic view of a conventional secondary battery.

[0036] Figure 2 is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention.

[0037] Figure 3 is a cross-sectional view of a positive electrode in the secondary battery electrode assembly according to the first embodiment of the present invention.

[0038] Figure 4 is a view of the secondary battery electrode assembly according to the first embodiment of the present invention when viewed in one direction.

[0039] Figure 5 is a view of the secondary battery electrode assembly according to the first embodiment of the present invention when viewed in another direction.

[0040] Figure 6 is a flowchart illustrating a method of connecting a positive electrode tab, a first metal member, and a positive electrode lead to each other in the secondary battery electrode assembly according to the first embodiment of the present invention.

[0041] Figure 7 is an exploded perspective view of a secondary battery electrode assembly according to a second embodiment of the present invention.

[0042] Figure 8It is a cross-sectional view of the negative electrode in a secondary battery electrode assembly according to a second embodiment of the present invention.

[0043] Figure 9 It is a view of a secondary battery electrode assembly according to a second embodiment of the present invention when viewed in one direction.

[0044] Figure 10 It is a view of a secondary battery electrode assembly according to a second embodiment of the present invention when viewed in another direction.

[0045] Figure 11 It is a flowchart illustrating a method of connecting a negative electrode tab, a second metal member, and a negative electrode lead to each other in a secondary battery electrode assembly according to a second embodiment of the present invention. Detailed Description

[0046] In this application, it should be understood that the terms "comprising", "having", "including", etc. specify the presence of the stated features, numbers, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0047] In addition, throughout the drawings, the same reference numerals will be used to refer to components that perform similar functions or operations. Throughout the specification, when a component is referred to as being connected to another component, the one component can not only be directly connected to the other component, but also the one component can be indirectly connected to the other component via another component. In addition, including a certain element does not mean excluding other elements, but means that such elements can also be included unless otherwise mentioned.

[0048] Hereinafter, a secondary battery electrode assembly according to the present invention and a battery cell including the secondary battery electrode assembly will be described with reference to the drawings.

[0049] Figure 2 It is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention, and Figure 3 It is a cross-sectional view of the positive electrode in a secondary battery electrode assembly according to a first embodiment of the present invention. As Figure 2 and Figure 3 shown, the secondary battery electrode assembly according to the present invention has a structure in which at least one positive electrode 100, at least one negative electrode 200, and at least one separator 300 are stacked.

[0050] Specifically, the separator 300 may be located between the positive electrode 100 and the negative electrode 300, on the upper surface of the uppermost negative electrode 300, or below the lowermost negative electrode 300; however, the present invention is not necessarily limited thereto.

[0051] In addition, the positive electrode lead 400 is electrically connected to the positive electrode 100, and the negative electrode lead 500 is electrically connected to the negative electrode 200. In particular, a first metal foil 600 is interposed between the positive electrodes 100 and between the positive electrode 100 and the positive electrode lead 400, which will be described in detail later.

[0052] First, the positive electrode 100 may include a positive electrode current collector 110 and a positive electrode tab 120. In a first preferred embodiment of the present invention, the positive electrode current collector 110 has a three-layer structure in which a first resin layer 112 is interposed between a pair of aluminum layers 111.

[0053] Here, each of the aluminum layers has a thickness of about 0.5 μm to 2 μm, and the first resin layer is made of polyethylene terephthalate (PET) and has a thickness of about 5 μm to 10 μm; however, the present invention is not necessarily limited thereto.

[0054] Stainless steel, nickel, titanium, sintered carbon, or aluminum or stainless steel treated with carbon, nickel, titanium, or silver on its surface may be used instead of aluminum as long as it can exhibit high conductivity without causing any chemical changes in the battery. In addition, a fine uneven pattern may be formed on its surface to increase the adhesion of the positive electrode active material, or various forms such as a film, sheet, foil, net, porous body, foam body, and non-woven fabric body may be used.

[0055] Each of the upper and lower surfaces of the pair of aluminum layers 111 exposed to the outside is provided with a positive electrode active material layer 113.

[0056] The following may be used as the positive electrode active material: layered compounds such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; lithium manganese oxides represented by the chemical formula Li 1+x Mn 2-x O4 (where x = 0 to 0.33), or lithium manganese oxides such as LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; Ni-site lithium nickel oxides represented by the chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); lithium manganese represented by the chemical formula LiMn 2-x M xO2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or a lithium manganese composite oxide represented by the chemical formula Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4, where a part of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; Fe2(MoO4)3; or LiNi x Mn 2-x O4 (0.01 ≤ x ≤ 0.6).

[0057] Meanwhile, the positive electrode active material can be mixed with a conductive agent and a binder, and a filler can be further added as needed.

[0058] The conductive agent is usually added in an amount of 1 wt% to 50 wt% based on the total weight of the mixture including the positive electrode active material. The conductive agent is not particularly limited as long as it exhibits conductivity and does not cause any chemical changes in the battery. For example, the following can be used as the conductive agent: graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black; conductive fibers, such as carbon fibers or metal fibers; metal powders, such as carbon fluoride powder, aluminum powder or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; or conductive materials, such as polyphenylene derivatives.

[0059] The binder is a component that helps the adhesion between the positive electrode active material and the conductive agent and the adhesion to the current collector. The binder is usually added in an amount of 1 wt% to 50 wt% based on the total weight of the mixture including the positive electrode active material. As an example of the binder, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene - propylene - diene terpolymer (EPDM), sulfonated EPDM, styrene - butadiene rubber, fluororubber and various copolymers can be used.

[0060] Meanwhile, an uncoated portion (not shown) of the positive electrode current collector 110 where the positive electrode active material layer is not formed is stamped into a predetermined shape to form a positive electrode tab 120.

[0061] The negative electrode 200 can include a negative electrode current collector 210 and a negative electrode tab 220. The negative electrode current collector 210 is usually manufactured to have a thickness of 3 μm to 500 μm. The negative electrode current collector is not particularly limited as long as it exhibits conductivity and does not cause any chemical changes in the battery. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium or sintered carbon. Alternatively, the negative electrode current collector can be made of copper or stainless steel whose surface is treated with carbon, nickel, titanium or silver, or an aluminum cadmium alloy.

[0062] In addition, the negative electrode current collector may form a fine uneven pattern on its surface to increase the adhesion of the negative electrode active material, or may be configured in any of various forms, such as a film, sheet, foil, net, porous body, foam body, and non-woven fabric body.

[0063] Each of the upper and lower surfaces of the negative electrode current collector 210 is provided with a negative electrode active material layer. As the negative electrode active material, for example, the following can be used: carbon, such as non-graphitized carbon or graphite-based carbon; metal composite oxides, such as Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Group 1, Group 2, and Group 3 of the periodic table, halogens; 0<x≤1; 1≤y≤3; 1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, or Bi2O5; conductive polymers, such as polyacetylene; Li-Co-Ni-based materials; or Si-based materials, such as Si, SiO, SiO2, or a mixture thereof; however, the present invention is not limited thereto.

[0064] Of course, the negative electrode active material may be further mixed with a conductive agent and a binder to form the negative electrode active material layer.

[0065] The conductive agent is a component configured to further improve the conductivity of the negative electrode active material, and can be used in a certain proportion: carbon black, such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal cracking carbon black; conductive fibers, such as carbon fibers or metal fibers; metal powders, such as carbon fluoride powder, aluminum powder, or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; or conductive materials, such as polyphenylene derivatives.

[0066] The binder is a component that helps the adhesion between the negative electrode active material and the conductive agent and the adhesion to the current collector, and the binder may include at least one selected from the group consisting of: styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), and polyacrylamide (PAM).

[0067] Meanwhile, an uncoated portion (not shown) of the negative current collector 210 where the negative active material layer is not formed is stamped into a predetermined shape to form a negative tab 220.

[0068] The separator 300 prevents short circuits between the positive electrode 100 and the negative electrode 200 and allows only lithium ions to migrate. Preferably, the separator is made of any one selected from polyethylene, polypropylene, double-layer polyethylene / polypropylene, triple-layer polyethylene / polypropylene / polyethylene, triple-layer polypropylene / polyethylene / polypropylene, and organic fiber filter paper; however, the present invention is not limited thereto.

[0069] Figure 4 is a view of a secondary battery electrode assembly according to a first embodiment of the present invention when viewed in one direction, Figure 5 is a view of a secondary battery electrode assembly according to a first embodiment of the present invention when viewed in another direction, and Figure 6 is a flowchart illustrating a method of connecting the positive tab, the first metal member, and the positive lead to each other in the secondary battery electrode assembly according to the first embodiment of the present invention.

[0070] will be described with reference to Figures 2 to 6 the electrical connection structure between the positive tab 120 and the positive lead 400.

[0071] Generally, the positive tab is made only of metal and can be connected to the positive lead by ultrasonic welding or the like. However, as described above, each of the positive current collector and the positive tab according to the first embodiment of the present invention has a structure in which a first resin layer is interposed between a pair of aluminum layers. That is, due to the first resin layer constituting each positive tab, it is difficult to firmly fix a plurality of positive tabs to each other by ultrasonic welding, and it is difficult to firmly fix the positive tab and the positive lead to each other.

[0072] Therefore, in the first embodiment of the present invention, a first metal foil 600 is provided between the positive tabs 120 and between the outermost positive tab 120 and the positive lead 400.

[0073] More specifically, the first metal foil 600 has a corrugated shape formed by bending a strip having a certain width and length, the corrugated shape having repeating ridges and valleys, and the first metal foil 600 is positioned at the edge of each positive tab 120 in the longitudinal direction.

[0074] Although the first metal foil 600 can be formed as a single piece and disposed on one edge of each positive electrode tab 120 in the longitudinal direction, it is more preferable that the first metal foil 600 includes a 1a metal foil 610 and a 1b metal foil 620, and the 1a metal foil 610 and the 1b metal foil 620 are respectively disposed on opposite edges of each positive electrode tab 120 in the longitudinal direction, so that the positive electrode tab 120 can be more firmly fixed to the positive electrode lead 400.

[0075] Therefore, the 1a metal foil 610 and / or the 1b metal foil 620 are located between the uppermost positive electrode tab 120 and the positive electrode lead 400, including between all positive electrode tabs 120, and the above components are fixed to each other by ultrasonic welding, whereby the positive electrode tab 120 is electrically connected to the positive electrode lead 400 via the first metal foil 600.

[0076] Meanwhile, the first metal foil 600 preferably contains the same aluminum material as the aluminum layer 111, but the material can be changed as long as the same function can be performed.

[0077] The length of the first metal foil 600 is not particularly limited, but it is preferable that the first metal foil does not protrude beyond the positive electrode tab 120.

[0078] The positive electrode lead 400 is preferably made of aluminum; however, the present invention is not necessarily limited thereto.

[0079] Figure 7 is an exploded perspective view of a secondary battery electrode assembly according to a second embodiment of the present invention, and Figure 8 is a cross-sectional view of the negative electrode in a secondary battery electrode assembly according to a second embodiment of the present invention.

[0080] The secondary battery electrode assembly according to the second embodiment of the present invention has a structure in which at least one positive electrode 100, at least one negative electrode 200, and at least one separator 300 are stacked in the same manner as in the first embodiment.

[0081] However, different from the first embodiment, in the second embodiment, the negative electrode 200 has a three-layer structure, and a second metal foil 700 is interposed between the negative electrode 200 and the negative electrode lead 500; therefore, repeated descriptions will be omitted, and only different configurations will be described.

[0082] The negative electrode 200 may include a negative electrode current collector 210 and a negative electrode tab 220. In a second preferred embodiment of the present invention, the negative electrode current collector 210 has a three-layer structure in which a second resin layer 212 is interposed between a pair of copper layers 211.

[0083] Here, each copper layer in the copper layer has a thickness of about 0.5 μm to 2.0 μm, and the second resin layer is made of polyethylene terephthalate (PET) and has a thickness of about 3 μm to 10 μm; however, the present invention is not necessarily limited thereto.

[0084] Of course, stainless steel or the like can be used instead of copper as long as it can exhibit high conductivity and does not cause any chemical changes in the battery.

[0085] Each of the upper and lower surfaces of a pair of copper layers 211 exposed to the outside is provided with a negative electrode active material layer 213. The negative electrode active material has been described previously, so the description of the negative electrode active material will be omitted.

[0086] Figure 9 is a view of a secondary battery electrode assembly according to a second embodiment of the present invention when viewed in one direction, Figure 10 is a view of a secondary battery electrode assembly according to a second embodiment of the present invention when viewed in another direction, and Figure 11 is a flowchart illustrating a method of connecting a negative electrode tab, a second metal member, and a negative electrode lead to each other in a secondary battery electrode assembly according to a second embodiment of the present invention.

[0087] Reference will be made to Figures 7 to 11 describe the electrical connection structure between the negative electrode tab 220 and the negative electrode lead 500.

[0088] Generally, the negative electrode tab is made only of metal and can be connected to the negative electrode lead by ultrasonic welding or the like. However, as described above, each of the negative electrode current collector and the negative electrode tab according to the second embodiment of the present invention has a structure in which a second resin layer is interposed between a pair of copper layers. That is, due to the second resin layer constituting each negative electrode tab, it is difficult to firmly fix a plurality of negative electrode tabs to each other by ultrasonic welding, and it is difficult to firmly fix the negative electrode tab and the negative electrode lead to each other.

[0089] Therefore, in the second embodiment of the present invention, a second metal foil 700 is provided between the negative electrode tabs 220 and between the outermost negative electrode tab 220 and the negative electrode lead 500.

[0090] More specifically, the second metal foil 700 has a corrugated shape formed by bending a strip having a certain width and length. The corrugated shape has repeating ridges and valleys, and the second metal foil 700 is positioned at the edge of each negative electrode tab 220 in the longitudinal direction.

[0091] Although the second metal foil 700 can be formed as a single piece and disposed on one edge in the longitudinal direction of each negative tab 220, it is more preferable that the second metal foil 700 includes a 2a metal foil 710 and a 2b metal foil 720, and the 2a metal foil 710 and the 2b metal foil 720 are respectively disposed on opposite edges in the longitudinal direction of each negative tab 220, so that the negative tab 220 can be more firmly fixed to the negative lead 500.

[0092] Therefore, the 2a metal foil 710 and / or the 2b metal foil 720 are located between the uppermost negative tab 220 and the negative lead 500, including between all the negative tabs 220, and the above components are fixed to each other by ultrasonic welding, whereby the negative tab 220 is electrically connected to the negative lead 500 via the second metal foil 700.

[0093] Meanwhile, the second metal foil 700 preferably contains the same copper material as the copper layer 111, nickel-plated copper, or a nickel-copper alloy, but the material can be changed as long as the same function can be performed.

[0094] The length of the second metal foil 700 is not particularly limited, but preferably, the second metal foil does not protrude beyond the negative tab 120.

[0095] Although not shown in the figure, a secondary battery electrode assembly according to a combination of the first embodiment and the second embodiment can be provided. For example, the positive electrode has a three-layer structure in which a first resin layer is interposed between a pair of aluminum layers, the negative electrode has a three-layer structure in which a second resin layer is interposed between a pair of copper layers, and a first metal foil and a second metal foil are respectively interposed between the positive tab and the positive lead and between the negative tab and the negative lead.

[0096] The present invention can provide a battery cell including the above secondary battery electrode assembly, a battery module or a battery pack including the battery cell, or a battery pack including the battery module.

[0097] Although the specific details of the present invention have been described in detail, those skilled in the art will understand that the detailed description only discloses the preferred embodiments of the present invention and thus does not limit the scope of the present invention. Therefore, those skilled in the art will understand that various changes and modifications are possible without departing from the scope and technical concept of the present invention, and it will be apparent that such changes and modifications fall within the scope of the appended claims.

[0098] (Description of reference numerals)

[0099] 100: Positive electrode

[0100] 110: Positive current collector

[0101] 111: Aluminum layer 112: First resin layer

[0102] 113: Positive electrode active material layer

[0103] 120: Positive electrode tab

[0104] 200: Negative electrode

[0105] 210: Negative electrode current collector

[0106] 211: Copper layer 212: Second resin layer

[0107] 213: Negative electrode active material layer

[0108] 220: Negative electrode tab

[0109] 300: Separator

[0110] 400: Positive electrode lead

[0111] 500: Negative electrode lead

[0112] 600: First metal foil

[0113] 610: 1a metal foil 620: 1b metal foil

[0114] 700: Second metal foil

[0115] 710: 2a metal foil 720: 2b metal

Claims

1. A secondary battery electrode assembly, comprising: at least one positive electrode, the positive electrode comprising a positive current collector and a positive electrode tab extending from the positive current collector in one direction; at least one negative electrode, the negative electrode comprising a negative electrode current collector and a negative electrode tab extending from the negative electrode current collector in one direction; a separator, the separator being interposed between the positive electrode and the negative electrode; a positive electrode lead electrically connected to the positive electrode tab; and A negative electrode lead, the negative electrode lead is electrically connected to the negative electrode tab, wherein: The positive electrode current collector has a first resin layer interposed between a pair of aluminum layers, and A first metal foil is interposed between the positive electrode tabs and between the outermost positive electrode tab and the positive electrode lead.

2. The secondary battery electrode assembly according to claim 1, wherein: The first metal foil is positioned along an edge of each of the positive electrode tabs in a longitudinal direction.

3. The secondary battery electrode assembly according to claim 2, wherein: The first metal foil includes a 1a metal foil and a 1b metal foil, and the 1a metal foil and the 1b metal foil are respectively positioned along opposite edges of each of the positive electrode tabs in the longitudinal direction.

4. The secondary battery electrode assembly according to claim 3, wherein: The first metal foil has a corrugated shape formed by bending a strip having a certain width and length, the corrugated shape having repeated ridges and valleys.

5. The secondary battery electrode assembly according to claim 3, wherein: The first metal foil includes aluminum.

6. The secondary battery electrode assembly according to claim 5, wherein: The positive electrode lead is fixed to the first metal foil and the aluminum layer by ultrasonic welding.

7. The secondary battery electrode assembly according to claim 1, wherein: The first resin layer is made of polyethylene terephthalate (PET).

8. The secondary battery electrode assembly according to claim 1, wherein: The negative electrode current collector has a second resin layer interposed between a pair of copper layers, and A second metal foil is interposed between the negative electrode tabs and between the outermost negative electrode tab and the negative electrode lead.

9. The secondary battery electrode assembly according to claim 8, wherein: The second metal foil is positioned along an edge of each of the negative electrode tabs in a longitudinal direction.

10. The secondary battery electrode assembly according to claim 9, wherein: The second metal foil includes a 2a metal foil and a 2b metal foil, and the 2a metal foil and the 2b metal foil are respectively positioned along opposite edges of each of the negative electrode tabs in the longitudinal direction.

11. The secondary battery electrode assembly according to claim 9, wherein: The second metal foil has a corrugated shape formed by bending a strip having a certain width and length, the corrugated shape of the second metal foil having repeated ridges and valleys.

12. The secondary battery electrode assembly according to claim 11, wherein: The second metal foil includes copper, nickel-plated copper, or a nickel-copper alloy.

13. The secondary battery electrode assembly according to claim 12, wherein: The negative electrode lead is fixed to the second metal foil and the copper layer by ultrasonic welding.

14. The secondary battery electrode assembly according to claim 9, wherein: The second resin layer is made of polyethylene terephthalate (PET). 15 . A battery cell comprising the secondary battery electrode assembly according to claim 1 .

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