Electrode assembly for secondary battery 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 first electrode comprises a first electrode current collector and a first electrode contact extending along one direction of the first electrode current collector; at least one second electrode including a second electrode current collector and a second electrode tab extending in one direction of the second electrode current collector; a separator interposed between the first electrode and the second electrode; a first electrode lead electrically connected to the first electrode tab; and a second electrode lead electrically connected to the second electrode tab, in which the first electrode current collector has a first resin layer interposed between the pair of aluminum layers, and the first metal foil is interposed in at least a partial region where the first electrode tab and the first electrode lead overlap each other.

Description

Technical Field

[0001] This application claims the priority of Korean Patent Application No. 2023-0124641 filed on September 19, 2023, and Korean Patent Application No. 2024-0016925 filed on February 2, 2024, the disclosures of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a secondary battery electrode assembly and a battery cell including the same, and more particularly, to a secondary battery electrode assembly having a structure in which electrode joints (each electrode joint having a resin layer interposed between a pair of metal layers) are firmly connected and fixed to electrode leads, and a battery cell including the same. Background Art

[0003] With the technological development of mobile devices and the increasing demand for them, secondary batteries that can be charged and discharged have been used as an energy source for various mobile devices. Secondary batteries, as an alternative to existing gasoline and diesel vehicles that use fossil fuels, have also attracted attention as an energy source for electric vehicles and hybrid vehicles.

[0004] According to the shape of the battery case, secondary batteries are classified into cylindrical batteries having an electrode assembly mounted in a cylindrical metal can, square batteries having an electrode assembly mounted in a square metal can, or pouch-shaped batteries having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate.

[0005] In particular, in the case of pouch-shaped 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 joints or a pair of electrode leads connected to the electrode joints protrude from one side or both sides of the battery case.

[0006] In addition, an aluminum current collector is generally used as a positive current collector on which a positive electrode active material is applied. However, since the aluminum current collector has been pointed out as a main cause of ignition for various reasons, research is being conducted to replace the aluminum current collector with a composite 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 expected that safety can be improved because the metal layer is thin and has a high resistance in the case of a short circuit, and the flow of current can be quickly cut off.

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

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

[0010] (Prior Art Documents)

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

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

[0016] Technical Solution

[0017] The secondary battery electrode assembly for achieving the above object according to the present invention includes: at least one first electrode including a first electrode current collector and a first electrode joint extending in one direction from the first electrode current collector; at least one second electrode including a second electrode current collector and a second electrode joint extending in one direction from the second electrode current collector; a separator interposed between the first electrode and the second electrode; a first electrode lead electrically connected to the first electrode joint; and a second electrode lead electrically connected to the second electrode joint, wherein the first electrode current collector has a first resin layer interposed between a pair of aluminum layers, and a first metal foil is interposed in at least a part of an area where the first electrode joint and the first electrode lead overlap each other.

[0018] In addition, in the secondary battery electrode assembly according to the present invention, the first electrode joint may be provided with at least two first cut lines formed in a longitudinal direction and spaced apart from each other by a predetermined distance, and the first metal foil may extend through the first cut lines, whereby both ends of the first metal foil may be exposed on one surface of the first electrode joint, and an intermediate portion of the first metal foil may be exposed on the other surface of the first electrode joint.

[0019] In addition, in the secondary battery electrode assembly according to the present invention, the first electrode may be provided in plurality, and one first metal foil may extend through the first cut line of the first electrode tab.

[0020] In addition, in the secondary battery electrode assembly according to the present invention, each of the first electrode and the first metal foil may be provided in plurality, and the number of the first electrodes and the number of the first metal foils are equal to each other, and one first metal foil may extend through the first cut line of one first electrode tab.

[0021] In addition, in the secondary battery electrode assembly according to the present invention, in the width direction, the width of the first metal foil may be greater than the width of the first electrode tab.

[0022] In addition, in the secondary battery electrode assembly according to the present invention, the first electrode lead may be positioned in close contact with one surface of the first electrode tab where both ends of the first metal foil are exposed.

[0023] In addition, in the secondary battery electrode assembly according to the present invention, the first metal foil may include aluminum.

[0024] In addition, in the secondary battery electrode assembly according to the present invention, the first electrode tab, the first electrode lead, and the first metal foil may be fixed to each other by ultrasonic welding.

[0025] In addition, in the secondary battery electrode assembly according to the present invention, the first resin layer may be made of polyethylene terephthalate (PET).

[0026] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode current collector may have a second resin layer interposed between a pair of copper layers, and the second metal foil may be interposed in at least a part of the region where the second electrode tab and the second electrode lead overlap each other.

[0027] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode tab may be provided therein with at least two second cut lines formed in the longitudinal direction while being spaced apart from each other by a predetermined distance, and the second metal foil may extend through the second cut lines, whereby both ends of the second metal foil may be exposed on one surface of the second electrode tab, and an intermediate portion of the second metal foil may be exposed on the other surface of the second electrode tab.

[0028] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode may be provided in plurality, and one second metal foil may extend through the second cut line of the second electrode tab.

[0029] In addition, in the secondary battery electrode assembly according to the present invention, each of the second electrode and the second metal foil may be provided in plurality, and the number of the second electrodes and the number of the second metal foils may be equal to each other, and one second metal foil may extend through the second cut line of one second electrode joint.

[0030] In addition, in the secondary battery electrode assembly according to the present invention, in the width direction, the width of the second metal foil may be greater than the width of the second electrode joint.

[0031] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode lead may be positioned in close contact with one surface of the second electrode joint where both ends of the second metal foil are exposed.

[0032] In addition, in the secondary battery electrode assembly according to the present invention, the second metal foil may include copper, nickel-plated copper, or a nickel-copper alloy.

[0033] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode joint, the second electrode lead, and the second metal foil may be fixed to each other by ultrasonic welding.

[0034] In addition, in the secondary battery electrode assembly according to the present invention, the second resin layer may be made of polyethylene terephthalate (PET).

[0035] In addition, the present invention provides a battery cell including the secondary battery electrode assembly.

[0036] In addition, the present invention provides a battery module including the battery cell.

[0037] Advantageous Effects

[0038] The secondary battery electrode assembly according to the present invention and the battery cell including the same have the following advantages: the metal foil extends through the cut line of the electrode joint in a zigzag shape to form a strip, whereby the electrode joints can be firmly fixed to each other.

[0039] In addition, the secondary battery electrode assembly according to the present invention and the battery cell including the same have the following advantages: ultrasonic welding is performed in a state where the strip-shaped metal foil, the electrode joint, and the electrode lead are in close contact with each other, whereby the electrode joint, the metal foil, and the electrode lead can be firmly fixed to each other. Description of the Drawings

[0040] Figure 1 is a partial schematic view of a conventional secondary battery.

[0041] Figure 2 is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention.

[0042] Figure 3It is a perspective view illustrating a method of fastening a first electrode terminal, a first metal foil, and a first electrode lead in Figure 2 the electrode assembly shown.

[0043] Figure 4 It is a cross-sectional view of a first electrode in a secondary battery electrode assembly according to a first embodiment of the present invention.

[0044] Figure 5 It is a top view of a secondary battery electrode assembly according to a first embodiment of the present invention.

[0045] Figure 6 It is a bottom view of a secondary battery electrode assembly according to a first embodiment of the present invention.

[0046] Figure 7 It is an exploded perspective view of a secondary battery electrode assembly according to a second embodiment of the present invention.

[0047] Figure 8 It is a front view of a secondary battery electrode assembly according to a second embodiment of the present invention.

[0048] Figure 9 It is a front view of a secondary battery electrode assembly according to a third embodiment of the present invention.

[0049] Figure 10 It is an exploded perspective view of a secondary battery electrode assembly according to a fourth embodiment of the present invention.

[0050] Figure 11 It is a perspective view illustrating a method of fastening a second electrode terminal, a second metal foil, and a second electrode lead in Figure 10 the electrode assembly shown.

[0051] Figure 12 It is a cross-sectional view of a second electrode in a secondary battery electrode assembly according to a fourth embodiment of the present invention.

[0052] Figure 13 It is a top view of a secondary battery electrode assembly according to a fourth embodiment of the present invention.

[0053] Figure 14 It is a bottom view of a secondary battery electrode assembly according to a fourth embodiment of the present invention. Detailed Embodiments

[0054] In the present application, it should be understood that the terms "comprising", "having", "including", etc. specify the presence of the described features, quantities, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof.

[0055] In addition, throughout the accompanying drawings, the same reference numerals will be used to refer to parts performing similar functions or operations. Throughout the specification, when a part is referred to as being connected to another part, not only can one part be directly connected to another part, but also one part can be indirectly connected to another part via yet another part. In addition, unless otherwise specified, including a certain element does not mean excluding other elements, but means that such elements can be further included.

[0056] Hereinafter, a secondary battery electrode assembly according to the present invention and a battery cell including the same will be described with reference to the accompanying drawings.

[0057] Figure 2 is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention, Figure 3 illustrates fastening a first electrode tab, a first metal foil, and a first electrode lead in Figure 2 the electrode assembly shown, and Figure 4 is a cross-sectional view of a first electrode in a secondary battery electrode assembly according to a first embodiment of the present invention.

[0058] As Figures 2 to 4 shown, the secondary battery electrode assembly according to the present invention has a structure in which at least one first electrode 100, at least one second electrode 200, and at least one separator 300 are stacked.

[0059] Here, the first electrode 100 may be a positive electrode, and the second electrode 200 may be a negative electrode. The separator 300 may be located between the first electrode 100 and the second electrode 200, on the uppermost second electrode 200, and below the lowermost second electrode 200; however, the present invention is not necessarily limited thereto.

[0060] In addition, the first electrode lead 400 is electrically connected to the first electrode 100, and the second electrode lead 500 is electrically connected to the second electrode 200. In particular, the first metal foil 600 is interposed between the first electrode 100 and the first electrode lead 400, which will be described in detail later.

[0061] First, the first electrode 100 may include a first electrode current collector 110 and a first electrode tab 120. In a first preferred embodiment of the present invention, the first 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.

[0062] 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.

[0063] In addition, aluminum can be replaced with stainless steel, nickel, titanium, sintered carbon, or aluminum or stainless steel whose surface is treated with carbon, nickel, titanium, or silver, as long as the material exhibits high electrical conductivity and does not cause any chemical changes in the battery. In addition, in order to increase the adhesion of the first electrode active material, the aluminum layer can have a microscale uneven pattern formed on its surface, or can be configured in any one of various forms such as films, sheets, foils, meshes, porous bodies, foams, and non-woven fabric bodies.

[0064] The first electrode active material layer 113 is provided on each of the upper and lower surfaces of a pair of aluminum layers 111 exposed to the outside.

[0065] 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 composite oxides represented by the chemical formula LiMn 2-x M x O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or the chemical formula Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which a part of Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3; or LiNi x Mn 2-x O4 (0.01 ≤ x ≤ 0.6) can be used as the first electrode active material.

[0066] In addition, the first electrode active material can be mixed with a conductive agent and a binder, and fillers can be further added as needed.

[0067] Based on the total weight of the mixture including the first electrode active material, a conductive agent is generally added in an amount of 1 wt% to 50 wt%. The conductive agent is not particularly limited as long as it exhibits high conductivity and does not cause any chemical changes in the battery to which it is applied. For example, 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 can be used as the conductive agent.

[0068] The binder is a component that helps bond the first electrode active material and the conductive agent and bond to the current collector. Based on the total weight of the mixture including the first electrode active material, the binder is generally added in an amount of 1 wt% to 50 wt%. 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.

[0069] In addition, an uncoated portion (not shown) of the first electrode current collector 110 where the first electrode active material layer is not formed is stamped into a predetermined shape to form the first electrode joint 120.

[0070] The second electrode 200 may include a second electrode current collector 210 and a second electrode joint 220. The second electrode current collector 210 is generally manufactured to have a thickness of 3 μm to 500 μm. The second electrode current collector is not particularly limited as long as it exhibits high conductivity and does not cause any chemical changes in the battery. For example, the second electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium or sintered carbon. Alternatively, the second 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.

[0071] In addition, the second electrode current collector may have a microscale uneven pattern formed on its surface to increase the adhesion of the second 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.

[0072] A second electrode active material layer is provided on each of the upper surface and the lower surface of the second electrode current collector 210. As the second electrode active material, for example, carbon such as non-graphitized carbon or graphite-based carbon; such as Li xFe2O3 (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, Group 1, Group 2 and Group 3 elements of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) such as metal composite oxides; 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 mixtures thereof; however, the present invention is not limited thereto.

[0073] Of course, the second electrode active material can be further mixed with a conductive agent and a binder to form a second electrode active material layer.

[0074] The conductive agent is a component configured to further improve the conductivity of the second electrode active material, and carbon blacks such as 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 can be used in a certain proportion.

[0075] The binder is a component that helps the adhesion between the second electrode active material and the conductive agent and the adhesion to the current collector, and 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).

[0076] In addition, the uncoated portion (not shown) of the second electrode current collector 210 where the second electrode active material layer is not formed is stamped into a predetermined shape to form a second electrode joint 220.

[0077] The separator 300 prevents short circuits between the first electrode 100 and the second electrode 200 and allows only the migration of lithium ions. 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.

[0078] Figure 5 is a top view of a secondary battery electrode assembly according to a first embodiment of the present invention, and Figure 6 is a bottom view of a secondary battery electrode assembly according to a first embodiment of the present invention.

[0079] will be described with reference to Figures 2 to 6 the electrical connection structure between the first electrode terminal 120, the first electrode lead 400, and the first metal foil 600.

[0080] Generally, the first electrode terminal is made only of metal and can be connected to the first electrode lead by ultrasonic welding or the like. However, as described above, each of the first electrode current collector and the first electrode terminal 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, since the first resin layer 112 is located in the middle of the first electrode terminal 120 in the thickness direction (y-axis direction), it is difficult to firmly fix a plurality of first electrode terminals 120 to the first electrode lead 400 by ultrasonic welding, and it is also difficult to electrically connect each of the first electrode terminals 120 to the first electrode lead 400.

[0081] Therefore, in the first embodiment of the present invention, first cut lines 121 are formed in each of the first electrode terminals 120 in the longitudinal direction (x-axis direction), and the first metal foil 600 is provided to extend through the first cut lines 121.

[0082] More specifically, two first cut lines 121 are provided in each of the first electrode terminals 120 in the longitudinal direction (x-axis direction) so as to be parallel to each other in a state of being spaced apart from each other by a predetermined distance.

[0083] Preferably, both ends of the first cut line 121 are located in the first electrode terminal 120 to prevent the first metal foil 600 extending through the first cut line 121 from separating.

[0084] When the first metal foil 600 extends through any one of the two first cut lines 121 and then extends through the other first cut line 121, the first metal foil 600 is exposed on two edges of the first electrode terminal 120 in the width direction (z-axis direction) (see Figure 5 ).

[0085] In contrast, on the rear surface of the first electrode terminal 120, neither of the two edges of the first metal foil 600 in the width direction (z-axis direction) is exposed, but the middle portion of the first metal foil is exposed (see Figure 6 ).

[0086] As a result, the first metal foil 600 is shaped like a strip extending in a zigzag manner through the two first cut lines 121, whereby the first electrode terminal 120 forms a bundle of terminals through the first metal foil 600.

[0087] The first electrode lead 400 is in close contact with a part of the first electrode terminal 120 and a part of the first metal foil 600, and is fixed thereto by ultrasonic welding.

[0088] At this time, the first electrode lead 400 preferably faces the exposed surface of the first metal foil 600 above the two edges of the first electrode terminal 120 in the width direction (z-axis direction). The reason is that when the first electrode lead 400 is coupled and fixed to the two edges of the first electrode terminal 120 in the width direction (z-axis direction), the movement of the first electrode lead in the width direction (z-axis direction) can be more effectively suppressed.

[0089] Of course, since the first metal foil 600 extends through the side surface of the first electrode terminal 120 (i.e., the first cut line 121), the first electrode terminal 120, the first metal foil 600, and the first electrode lead 400 are electrically connected to each other.

[0090] Preferably, the width of the first metal foil 600 (in the z-axis direction) is not greater than the width of the first electrode terminal 120, and more preferably, the length of the first metal foil 600 (in the x-axis direction) is slightly less than the length of the first cut line 121.

[0091] In addition, the first metal foil 600 is preferably made of the same material as the aluminum layer 111 (i.e., aluminum), but the material can be changed if the first metal foil can perform the same function, and the first electrode lead 400 is preferably made of aluminum; however, the present invention is not necessarily limited thereto.

[0092] 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 front view of a secondary battery electrode assembly according to a second embodiment of the present invention.

[0093] In the first embodiment, a plurality of first electrode terminals are stacked, and a single first metal foil extends through the first cut lines of the first electrode terminals. In the second embodiment, a plurality of first electrodes and a plurality of first metal foils are provided, wherein the number of first electrodes is equal to the number of first metal foils, and one first metal foil extends through the first cut line of one first electrode terminal.

[0094] In the second embodiment, a predetermined portion of the first metal foil 600 is in close contact with each other, and the contact area between the first electrode tab 120 and the first metal foil 600 is increased, whereby a lower resistance can be maintained.

[0095] Figure 9 is a front view of a secondary battery electrode assembly according to a third embodiment of the present invention. The third embodiment is the same as the second embodiment except that the width of the first metal foil 600 (in the z-axis direction) is greater than the width of the first electrode tab 120.

[0096] In the third embodiment, at least one of the opposite edges of the first metal foil 600 protrudes outward from the edge of the first electrode tab 120, whereby the first metal foil 600 can be more firmly fixed. In other words, since no first resin layer 112 is located between the portions of the first metal foil 600 extending outward from the edge of the first electrode tab 120, the first metal foil 600 is firmly coupled by ultrasonic welding.

[0097] Figure 10 is an exploded perspective view of a secondary battery electrode assembly according to a fourth embodiment of the present invention, Figure 11 illustrates fastening a second electrode tab, a second metal foil, and a second electrode lead in the Figure 10 shown electrode assembly, and Figure 12 is a cross-sectional view of a second electrode in a secondary battery electrode assembly according to a fourth embodiment of the present invention.

[0098] In the same manner as in the first embodiment, the secondary battery electrode assembly according to the fourth embodiment of the present invention has a structure in which at least one first electrode 100, at least one second electrode 200, and at least one separator 300 are laminated.

[0099] However, different from the first embodiment, in the second embodiment, the second electrode 200 has a three-layer structure, and the second metal foil 700 is interposed between the second electrode 200 and the second electrode lead 500. Therefore, its repeated description will be omitted, and only different configurations will be described.

[0100] The second electrode 200 may include a second electrode current collector 210 and a second electrode tab 220. In a second preferred embodiment of the present invention, the second 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.

[0101] Here, 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.

[0102] Of course, stainless steel or the like can be used instead of copper, as long as it can exhibit high electrical conductivity without causing any chemical changes in the battery.

[0103] The second electrode active material layer 213 is disposed on each of the upper and lower surfaces of a pair of copper layers 211 exposed to the outside. The second electrode active material layer has been described previously, and thus its description will be omitted.

[0104] Figure 13 is a top view of a secondary battery electrode assembly according to a fourth embodiment of the present invention, and Figure 14 is a bottom view of a secondary battery electrode assembly according to a fourth embodiment of the present invention.

[0105] will be described with reference to Figures 10 to 14 the electrical connection structure between the second electrode joint 220, the second electrode lead 500, and the second metal foil 700.

[0106] Generally, the second electrode joint is made of only metal and can be coupled to the second electrode lead by ultrasonic welding or the like. However, as described above, each of the second electrode current collector and the second electrode joint according to the fourth embodiment of the present invention has a structure in which a second resin layer is interposed between a pair of copper layers. That is, since the second resin layer 212 is located in the middle of the second electrode joint 220 in the thickness direction (y-axis direction), it is difficult to firmly fix a plurality of second electrode joints 220 to the second electrode lead 500 by ultrasonic welding, and it is also difficult to electrically connect each of the second electrode joints 220 to the second electrode lead 500.

[0107] Therefore, in the fourth embodiment of the present invention, second cut lines 221 are formed in each of the second electrode joints 220 in the longitudinal direction (x-axis direction), and the second metal foil 700 is disposed to extend through the second cut lines 221.

[0108] More specifically, two second cut lines 221 are provided in each of the second electrode joints 220 in the longitudinal direction (x-axis direction) so as to be parallel to each other in a state of being spaced apart from each other by a predetermined distance.

[0109] Preferably, both ends of the second cut line 221 are located in the second electrode joint 220 to prevent the second metal foil 700 extending through the second cut line 221 from separating.

[0110] When the second metal foil 700 extends through any one of the two second cut lines 221 and then extends through the other second cut line 221, the second metal foil 700 is exposed on two edges of the second electrode joint 220 in the width direction (z-axis direction) (see Figure 13 ).

[0111] In contrast, on the rear surface of the second electrode joint 220, neither edge of the second metal foil 700 in the width direction (z-axis direction) is exposed, but the middle portion of the second metal foil is exposed (see Figure 14 ).

[0112] As a result, the second metal foil 700 is shaped like a strip extending in a zigzag manner through the two second cut lines 221, whereby the second electrode joint 220 forms a joint bundle through the second metal foil 700.

[0113] The second electrode lead 500 is in close contact with a part of the second electrode joint 220 and a part of the second metal foil 700, and is fixed thereto by ultrasonic welding.

[0114] At this time, the second electrode lead 500 preferably faces the exposed surface of the second metal foil 700 above the two edges of the second electrode joint 220 in the width direction (z-axis direction). The reason is that when the second electrode lead 500 is coupled and fixed to the two edges of the second electrode joint 220 in the width direction (z-axis direction), the movement of the second electrode lead in the width direction (z-axis direction) can be more effectively suppressed.

[0115] Of course, since the second metal foil 700 extends through the side surface of the second electrode joint 220 (i.e., the second cut line 221), the second electrode joint 220, the second metal foil 700, and the second electrode lead 500 are electrically connected to each other.

[0116] Preferably, the width (in the z-axis direction) of the second metal foil 700 is not greater than the width of the second electrode joint 220, and more preferably, the length (in the x-axis direction) of the second metal foil 700 is slightly less than the length of the second cut line 221.

[0117] In addition, the second metal foil 700 is preferably made of a material the same as or similar to that of the copper layer 211 (e.g., copper, nickel-plated copper, or nickel-copper alloy), but the material can be changed if the second metal foil can perform the same function, and the second electrode lead 500 is preferably made of copper or nickel; however, the present invention is not necessarily limited thereto.

[0118] Although not shown in the figure, the second electrode joint, the second electrode lead, and the second metal foil can be connected to each other in the same manner as in the second embodiment or the third embodiment.

[0119] In addition, the present invention provides a secondary battery electrode assembly having a combination of the first embodiment to the fourth embodiment.

[0120] In addition, the present invention provides a battery cell, a battery module including the secondary battery electrode assembly, a battery pack including the battery cell, or a battery pack including the battery module.

[0121] Although the specific details of the present invention have been described in detail, those skilled in the art will understand that its 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 can be made without departing from the category and technical concept of the present invention, and it is obvious that such changes and modifications fall within the scope of the appended claims.

[0122] (Description of reference numerals)

[0123] 100: First electrode

[0124] 110: First current collector

[0125] 111: Aluminum layer 112: First resin layer

[0126] 113: First electrode active material layer

[0127] 120: First electrode terminal

[0128] 121: First cut line

[0129] 200: Second electrode

[0130] 210: Second current collector

[0131] 211: Copper layer 212: Second resin layer

[0132] 213: Second electrode active material layer

[0133] 220: Second electrode terminal

[0134] 221: Second cut line

[0135] 300: Separator

[0136] 400: First electrode lead

[0137] 500: Second electrode lead

[0138] 600: First metal foil

[0139] 700: Second metal foil

Claims

1. A secondary battery electrode assembly, characterized in that: The secondary battery electrode assembly comprises: At least one first electrode, the at least one first electrode comprising a first electrode current collector and a first electrode connector extending along a side direction of the first electrode current collector; at least one second electrode, the at least one second electrode comprising a second electrode current collector and a second electrode connector extending along a side direction of the second electrode current collector; a diaphragm interposed between the first electrode and the second electrode; a first electrode lead electrically connected to the first electrode tab; and a second electrode lead, the second electrode lead being electrically connected to the second electrode contact, wherein The first electrode current collector has a first resin layer interposed between a pair of aluminum layers, and A first metal foil is interposed in at least a portion of a region where the first electrode tab and the first electrode lead overlap each other.

2. The secondary battery electrode assembly according to claim 1, characterized in that: At least two first cut lines are provided in the first electrode tab and are spaced apart from each other by a predetermined distance in a longitudinal direction, and The first metal foil extends through the first cut line, whereby both ends of the first metal foil are exposed on one surface of the first electrode tab and a middle portion of the first metal foil is exposed on the other surface of the first electrode tab.

3. The secondary battery electrode assembly according to claim 2, characterized in that: The first electrode is provided in plurality, and A first metal foil extends across the first kerf line of the first electrode tab.

4. The secondary battery electrode assembly according to claim 2, characterized in that: Each of the first electrode and the first metal foil is provided in plural numbers, and the number of the first electrodes and the number of the first metal foils are equal to each other, and A first metal foil extends through the first cut line of a first electrode contact.

5. The secondary battery electrode assembly according to claim 4, characterized in that: In a width direction, the width of the first metal foil is greater than the width of the first electrode tab.

6. The secondary battery electrode assembly according to claim 2, characterized in that: The first electrode lead is positioned to be in close contact with one surface of the first electrode tab, and both ends of the first metal foil are exposed on the one surface of the first electrode tab.

7. The secondary battery electrode assembly according to claim 2, characterized in that: The first metal foil includes aluminum.

8. The secondary battery electrode assembly according to claim 2, characterized in that: The first electrode tab, the first electrode lead, and the first metal foil are fixed to each other by ultrasonic welding.

9. The secondary battery electrode assembly according to claim 2, characterized in that: The first resin layer is made of polyethylene terephthalate (PET).

10. The secondary battery electrode assembly according to claim 1, characterized in that: The second electrode current collector has a second resin layer interposed between a pair of copper layers, and A second metal foil is interposed in at least a portion of a region where the second electrode tab and the second electrode lead overlap each other.

11. The secondary battery electrode assembly according to claim 10, characterized in that: At least two second cut lines are provided in the second electrode tab and are spaced apart from each other by a predetermined distance in the longitudinal direction, and The second metal foil extends across the second cut line, whereby both ends of the second metal foil are exposed on one surface of the second electrode tab and a middle portion of the second metal foil is exposed on the other surface of the second electrode tab.

12. The secondary battery electrode assembly according to claim 11, characterized in that: The second electrode is provided in plurality, and A second metal foil extends across the second kerf line of the second electrode tab.

13. The secondary battery electrode assembly according to claim 11, characterized in that: Each of the second electrode and the second metal foil is provided in plural, and the number of the second electrodes and the number of the second metal foil are equal to each other, and A second metal foil extends across the second cut line of a second electrode contact.

14. The secondary battery electrode assembly according to claim 13, characterized in that: In a width direction, the width of the second metal foil is greater than the width of the second electrode tab.

15. The secondary battery electrode assembly according to claim 11, characterized in that: The second electrode lead is positioned to be in close contact with one surface of the second electrode tab, and both ends of the second metal foil are exposed on the one surface of the second electrode tab.

16. The secondary battery electrode assembly according to claim 11, characterized in that: The second metal foil includes copper, nickel-plated copper or a nickel-copper alloy.

17. The secondary battery electrode assembly according to claim 11, characterized in that: The second electrode tab, the second electrode lead, and the second metal foil are fixed to each other by ultrasonic welding.

18. The secondary battery electrode assembly according to claim 11, characterized in that: The second resin layer is made of polyethylene terephthalate (PET). 19 . A battery cell comprising the secondary battery electrode assembly according to claim 1 .

20. A battery module comprising the battery cell according to claim 19.

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