Secondary battery electrode assembly and battery cell including the same

Abstract

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 and a battery cell including the same, comprising: one or more first electrodes including a first electrode collector and a first electrode tab extending in one direction from the first electrode collector; one or more second electrodes including a second electrode collector and a second electrode tab extending in one direction from the second electrode 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, wherein the first electrode collector has a first resin layer interposed between a pair of aluminum layers, and a first metal foil interposed in at least a region where the first electrode tab and the first electrode lead overlap.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0124641 filed on September 19, 2023, and Korean Patent Application No. 10-2024-0016925 filed on February 2, 2024, and all contents disclosed in the Korean patent applications are incorporated herein by reference.

[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 an electrode tab and an electrode lead are firmly connected and fixed, the electrode tab having a structure in which a resin layer is interposed between a pair of metal layers, and a battery cell including the same. [Background technology]

[0003] As technology development and demand for mobile devices increases, rechargeable secondary batteries are being used as energy sources for various mobile devices. Secondary batteries are also attracting attention as energy sources for electric vehicles and hybrid electric vehicles, which are being proposed as alternatives to existing gasoline-powered vehicles and diesel-powered vehicles that use fossil fuels.

[0004] Depending on the shape of the battery case, secondary batteries are classified into cylindrical batteries and prismatic batteries, in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch batteries, in which the electrode assembly is housed in a pouch-shaped case made of an aluminum laminate sheet.

[0005] In particular, in the case of a pouch-type secondary battery, a number of positive and negative electrodes having a predetermined size are stacked in sequence with a separator interposed between them, and an electrode tab or a pair of electrode leads connected to the electrode tabs protrudes from one or both sides of the case to the outside.

[0006] Meanwhile, aluminum current collectors are commonly used as positive electrode current collectors on which positive electrode active materials are applied. However, because aluminum current collectors have been identified as a major cause of fires due to various reasons, research is being conducted to replace them with composite current collectors, for example, current collectors with a structure in which a resin layer is sandwiched between two metal layers.

[0007] When using such a three-layered current collector, the metal layer is thin and has high resistance in the event of a short circuit, allowing the flow of current to be quickly cut off, which is expected to improve safety.

[0008] Figure 1 is a partial schematic diagram of a secondary battery according to the prior art. As shown in Figure 1, the electrode assembly 10 has a structure in which a number of tabs 20 extend outward, electrode leads 30 are interposed between these tabs 20, and the tabs 20 are then fixed together by welding.

[0009] However, in the case of a current collector with a three-layer structure, since it has a resin layer in the middle, it is difficult to join the electrode tab and the electrode lead by commonly used welding methods. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 10-2022-0124358 [Patent Document 2] Korean Patent Publication No. 10-2023-0020177 Summary of the Invention [Problem to be solved by the invention]

[0011] In order to solve the above problems, an object of the present invention is to provide a secondary battery electrode assembly having a structure in which electrode current collectors, each having a resin layer interposed between metal layers, can be firmly connected to each other, and a battery cell including the same.

[0012] Another object of the present invention is to provide a secondary battery electrode assembly having a structure capable of firmly connecting an electrode current collector and an electrode lead, in which a resin layer is interposed between metal layers, and a battery cell including the same. [Means for solving the problem]

[0013] To solve the above problems, a secondary battery electrode assembly according to the present invention includes one or more first electrodes including a first electrode collector and a first electrode tab extending in one direction from the first electrode collector, one or more second electrodes including a second electrode collector and a second electrode tab extending in one direction from the second electrode 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, wherein the first electrode collector has a first resin layer interposed between a pair of aluminum layers, and a first metal foil interposed in at least a region where the first electrode tab and the first electrode lead overlap.

[0014] In addition, in the secondary battery electrode assembly according to the present invention, two or more first incision lines are provided inside the first electrode tab at regular intervals in the longitudinal direction, and the first metal foil passes through the first incision lines, so that both ends of the first metal foil are exposed on one side of the first electrode tab, and a central portion of the first metal foil is exposed on the other side of the first electrode tab.

[0015] In the electrode assembly for a secondary battery according to the present invention, the first electrodes are plural, and one of the first metal foils passes through the first cut line of the first electrode tab.

[0016] In addition, in the secondary battery electrode assembly according to the present invention, the first electrodes and the first metal foils are plural and equal in number, and one first metal foil passes through the first incision line of one first electrode tab.

[0017] In the secondary battery electrode assembly according to the present invention, the width of the first metal foil is longer than the width of the first electrode tab in the width direction.

[0018] In the secondary battery electrode assembly according to the present invention, the first electrode lead is positioned to be in close contact with one surface of the first electrode tab where both ends of the first metal foil are exposed.

[0019] In the secondary battery electrode assembly according to the present invention, the first metal foil contains aluminum.

[0020] In the secondary battery electrode assembly according to the present invention, the first electrode tab, the first electrode lead, and the first metal foil are fixed to each other by ultrasonic welding.

[0021] In the secondary battery electrode assembly according to the present invention, the first resin layer is made of PET (polyethylene terephthalate).

[0022] In addition, in the secondary battery electrode assembly according to the present invention, the second electrode collector is characterized in that a second resin layer is interposed between a pair of copper layers, and a second metal foil is interposed in at least a portion of the area where the second electrode tab and the second electrode lead overlap.

[0023] In addition, in the secondary battery electrode assembly according to the present invention, two or more second incision lines are provided inside the second electrode tab at regular intervals in the longitudinal direction, and the second metal foil passes through the second incision lines, so that both ends of the second metal foil are exposed on one side of the second electrode tab, and a central portion of the second metal foil is exposed on the other side of the second electrode tab.

[0024] In the electrode assembly for a secondary battery according to the present invention, the second electrodes are plural, and one second metal foil passes through the second cut line of the second electrode tab.

[0025] In addition, in the secondary battery electrode assembly according to the present invention, the second electrodes and the second metal foils are of equal numbers and are plural, and one second metal foil passes through the second incision line of one second electrode tab.

[0026] In the secondary battery electrode assembly according to the present invention, the width of the second metal foil is longer than the width of the second electrode tab in the width direction.

[0027] In the secondary battery electrode assembly according to the present invention, the second electrode lead is positioned to be in close contact with one surface of the second electrode tab where both ends of the second metal foil are exposed.

[0028] In the secondary battery electrode assembly according to the present invention, the second metal foil may include copper, nickel-coated copper, or a nickel-copper alloy.

[0029] In the secondary battery electrode assembly according to the present invention, the second electrode tab, the second electrode lead, and the second metal foil are fixed to each other by ultrasonic welding.

[0030] In the secondary battery electrode assembly according to the present invention, the second resin layer is made of a PET (polyethylene terephthalate) material.

[0031] The present invention also provides a battery cell including the above-described secondary battery electrode assembly.

[0032] The present invention is also characterized by a battery module including the above-described battery cell. [Effects of the Invention]

[0033] According to the secondary battery electrode assembly and the battery cell including the same of the present invention, the metal foil passes through the cut lines of the electrode tabs in a zigzag pattern to form a ribbon shape, which has the advantage that the electrode tabs can be firmly fixed to each other.

[0034] Furthermore, according to the secondary battery electrode assembly and the battery cell including the same of the present invention, ultrasonic welding is performed with the ribbon-shaped metal foil, electrode tab, and electrode lead in close contact with each other, which has the advantage of enabling the electrode tab, metal foil, and electrode lead to be securely fixed. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a partial schematic diagram of a secondary battery according to the prior art. [Figure 2] 1 is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention; [Figure 3] 3 is a perspective view illustrating a method of fastening a first electrode tab, a first metal foil, and a first electrode lead in the electrode assembly shown in FIG. 2. FIG. [Figure 4] 1 is a cross-sectional view of a first electrode of a secondary battery electrode assembly according to a first embodiment of the present invention. [Figure 5] 1 is a top view of a secondary battery electrode assembly according to a first embodiment of the present invention; [Figure 6] 1 is a bottom view of a secondary battery electrode assembly according to a first embodiment of the present invention; [Figure 7] FIG. 10 is an exploded perspective view of a secondary battery electrode assembly according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a front view of a secondary battery electrode assembly according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a front view of a secondary battery electrode assembly according to a third embodiment of the present invention. [Figure 10] FIG. 10 is an exploded perspective view of a secondary battery electrode assembly according to a fourth embodiment of the present invention. [Figure 11] 11 is a perspective view illustrating a method of fastening a second electrode tab, a second metal foil, and a second electrode lead in the electrode assembly shown in FIG. 10. FIG. [Figure 12] 10 is a cross-sectional view of a second electrode of a secondary battery electrode assembly according to a fourth embodiment of the present invention. [Figure 13]FIG. 10 is a top view of a secondary battery electrode assembly according to a fourth embodiment of the present invention. [Figure 14] FIG. 10 is a bottom view of a secondary battery electrode assembly according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] In this application, the use of words such as "comprises," "has," or "has" is intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but should be understood as not precluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0037] Furthermore, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only a direct connection but also an indirect connection via another element therebetween. Furthermore, unless otherwise specified, "including a certain element" does not mean that other elements are excluded, but that other elements may also be included.

[0038] Hereinafter, a secondary battery electrode assembly and a battery cell including the same according to the present invention will be described with reference to the accompanying drawings.

[0039] FIG. 2 is an exploded perspective view of a secondary battery electrode assembly according to a first embodiment of the present invention, FIG. 3 is a perspective view illustrating a method of fastening a first electrode tab, a first metal foil, and a first electrode lead in the electrode assembly shown in FIG. 2, and FIG. 4 is a cross-sectional view of a first electrode of the secondary battery electrode assembly according to the first embodiment of the present invention.

[0040] As shown in FIGS. 2 to 4, the secondary battery electrode assembly according to the present invention has a structure in which one or more first electrodes 100, one or more second electrodes 200, and one or more separators 300 are stacked.

[0041] 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, or below the lowermost second electrode 200, but is not limited thereto.

[0042] In addition, a first electrode lead 400 is electrically connected to the first electrode 100, and a second electrode lead 500 is electrically connected to the second electrode 200. In particular, a first metal foil 600 is interposed between the first electrode 100 and the first electrode lead 400, which will be described in detail later.

[0043] First, the first electrode 100 may include a first electrode collector 110 and a first electrode tab 120. The first electrode collector 110 according to the first preferred embodiment of the present invention may have a three-layer structure in which a first resin layer 112 is interposed between a pair of aluminum layers 111.

[0044] Here, the thickness of the aluminum layer is approximately 0.5 to 2 μm, and the first resin layer is made of polyethylene terephthalate (PET) material and has a thickness of approximately 5 to 10 μm, but is not necessarily limited to this.

[0045] In addition, instead of aluminum, stainless steel, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used as long as it does not cause chemical changes in the battery and has high conductivity. In addition, to increase the adhesive strength of the first electrode active material, the surface may be formed with fine irregularities, or various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric may be used.

[0046] The pair of aluminum layers 111 has a first electrode active material layer 113 on each of the upper and lower surfaces exposed to the outside.

[0047] The first electrode active material is a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x Lithium manganese oxides such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, and Cu2V2O7; and 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); 2-x M x Lithium manganese composite oxides expressed as Li2Mn3MO8 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1); LiMn2O4, in which part of the Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, LiNi x Mn 2-x O4 (0.01≦x≦0.6) can be used.

[0048] Meanwhile, the first electrode active material may be mixed with a conductive material and a binder, and a filler may also be added as needed.

[0049] The conductive material is typically added in an amount of 1 to 50 wt % based on the total weight of the mixture including the first electrode active material. The conductive material is not particularly limited as long as it is conductive without causing any chemical changes in the battery, and examples of such conductive materials include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0050] The binder is a component that helps bind the first electrode active material to the conductive material and to the current collector, and is typically added in an amount of 1 to 50 wt % based on the total weight of the mixture including the first electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butylene rubber, fluororubber, and various copolymers.

[0051] Meanwhile, a first electrode tab 120 is formed by punching out a non-coating portion (not shown) of the first electrode current collector 110 where the first electrode active material layer is not formed into a predetermined shape.

[0052] The second electrode 200 can be composed of a second electrode current collector 210 and a second electrode tab 220. The second electrode current collector 210 is generally manufactured to have a thickness of 3 to 500 μm, and is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, a surface of copper stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum cadmium alloy, etc. can be used.

[0053] Also, fine irregularities can be formed on the surface to strengthen the binding force of the second electrode active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven bodies, etc. can be used.

[0054] A second electrode active material layer is provided on the upper and lower surfaces of the second electrode current collector 210. As the second electrode active material, for example, carbon such as graphitized carbon and graphite-based carbon; 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, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0<x≦1; 1≦y≦3; 1≦z≦8) and other metal composite oxides; lithium metal; lithium alloys; silicon-based alloys; tin-based alloys; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Si-based materials that are Si, SiO, SiO2 alone or mixtures thereof, etc. can be used, but are not limited to only these.

[0055] Of course, a conductive material and a binder can be further mixed with the second electrode active material to form the second electrode active material layer.

[0056] The conductive material is a component for further improving the conductivity of the second electrode active material, and may be selected from carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives, all of which may be used in a certain ratio.

[0057] The binder is a component that helps bind the second electrode active material to the conductive material and 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, fluoro rubber, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), and polyacryl amide (PAM).

[0058] Meanwhile, a non-coating portion (not shown) of the second electrode current collector 210 where the second electrode active material layer is not formed is punched out into a predetermined shape to form a second electrode tab 220.

[0059] The separator 300 prevents a short circuit between the first electrode 100 and the second electrode 200 and allows only the movement of lithium ions. The material of the separator is preferably any one selected from the group consisting of polyethylene, polypropylene, a polyethylene / polypropylene double layer, a polyethylene / polypropylene / polyethylene triple layer, a polypropylene / polyethylene / polypropylene triple layer, and organic fiber filter paper, but is not limited thereto.

[0060] FIG. 5 is a top view of the secondary battery electrode assembly according to the first embodiment of the present invention, and FIG. 6 is a bottom view of the secondary battery electrode assembly according to the first embodiment of the present invention.

[0061] 2 to 6, the electrical connection structure of the first electrode tab 120, the first electrode lead 400, and the first metal foil 600 will be described.

[0062] Generally, the first electrode tabs are made of metal only and can be connected to the first electrode leads by ultrasonic welding, etc. However, as described above, the first electrode current collector and first electrode tab according to the first embodiment of the present invention have a structure in which a first resin layer is interposed between a pair of aluminum layers. That is, due to the first resin layer 112 located at the center of the first electrode tab 120 in the thickness direction (y-axis direction), it is difficult to firmly fix the multiple first electrode tabs 120 to the first electrode leads 400 using ultrasonic welding, and it is also difficult to electrically connect each first electrode tab 120 to the first electrode lead 400.

[0063] Therefore, in the first embodiment of the present invention, the first cutting line 121 is formed in the longitudinal direction (x-axis direction) of the first electrode tab 120, while the first metal foil 600 is disposed so as to penetrate the first cutting line 121.

[0064] More specifically, two first incision lines 121 are provided along the longitudinal direction (x-axis direction) of the first electrode tab 120, spaced apart at a regular interval and parallel to each other.

[0065] Here, both ends of the first cutting line 121 are preferably positioned inside the first electrode tab 120 so that the first metal foil 600 passing through the first cutting line 121 does not come off.

[0066] After the first metal foil 600 passes through one of the two first incision lines 121, when it passes through the other first incision line 121, the first metal foil 600 is exposed from both edges of the first electrode tab 120 in the width direction (z-axis direction) (see Figure 5).

[0067] Meanwhile, the first metal foil 600 is not exposed at both edges in the width direction (z-axis direction) of the rear surface of the first electrode tab 120, but the central portion is exposed (see FIG. 6).

[0068] As a result, the first metal foil 600 has a ribbon shape passing through the two first incision lines 121 in a zigzag pattern, and the first electrode tabs 120 form a single tab bundle by the first metal foil 600 .

[0069] The first electrode lead 400 is then brought into close contact with a portion of the first electrode tab 120 and a portion of the first metal foil 600, and then fixed thereto by ultrasonic welding.

[0070] Here, it is preferable that the first electrode lead 400 faces the exposed surface of the first metal foil 600 at both edges in the width direction (z-axis direction) of the first electrode tab 120. This is because the bonding and fixing of the first electrode lead 400 to both edges in the width direction (z-axis direction) of the first electrode tab 120 is more effective in suppressing loose movement in the width direction (z-axis direction).

[0071] Of course, the first metal foil 600 penetrates the side of the first electrode tab 120, that is, the first incision line 121, so that the first electrode tab 120, the first metal foil 600, and the first electrode lead 400 are electrically connected to one another.

[0072] It is preferable that the width (z-axis direction) of the first metal foil 600 does not exceed the width of the first electrode tab 120, and it is more preferable that the length (x-axis direction) of the first metal foil 600 is slightly shorter than the length of the first incision line 121.

[0073] On the other hand, the first metal foil 600 is preferably made of the same aluminum material as the aluminum layer 111, but this can be changed as long as it can perform the same function, and the first electrode lead 400 is preferably made of an aluminum material, but is not necessarily limited to this.

[0074] FIG. 7 is an exploded perspective view of a secondary battery electrode assembly according to a second embodiment of the present invention, and FIG. 8 is a front view of the secondary battery electrode assembly according to the second embodiment of the present invention.

[0075] In the first embodiment described above, a large number of first electrode tabs are stacked, and then one first metal foil penetrates the first incision, whereas in the second embodiment, the number of first electrodes and first metal foils is equal and plural, and one first metal foil penetrates the first incision line of one first electrode tab.

[0076] In the second embodiment, certain portions of the first metal foils 600 are in close contact with each other, and the contact area between each first electrode tab 120 and the first metal foil 600 increases, so that the resistance can be maintained low.

[0077] 9 is a front view of a secondary battery electrode assembly according to a third embodiment of the present invention, which is the same as the second embodiment except that the width (z-axis direction) of the first metal foil 600 exceeds the width of the first electrode tab 120.

[0078] In the third embodiment, one or both edge portions of the first metal foil 600 protrude outward from the edge of the first electrode tab 120, which allows for more secure fixation of the first metal foil 600. In other words, the first resin layer 112 is not positioned between the first metal foil 600 in the portion extending outward from the edge of the first electrode tab 120, allowing for reliable bonding of the first metal foil 600 by ultrasonic welding.

[0079] FIG. 10 is an exploded perspective view of a secondary battery electrode assembly according to a fourth embodiment of the present invention, FIG. 11 is a perspective view for explaining a method of fastening a second electrode tab, a second metal foil, and a second electrode lead in the electrode assembly shown in FIG. 10, and FIG. 12 is a cross-sectional view of a second electrode of the secondary battery electrode assembly according to the fourth embodiment of the present invention.

[0080] The secondary battery electrode assembly according to the fourth embodiment of the present invention has a structure in which one or more first electrodes 100, one or more second electrodes 200, and one or more separators 300 are stacked, similar to the first embodiment.

[0081] However, unlike the first embodiment, in the fourth embodiment, the second electrode 200 has a three-layer structure, and a second metal foil 700 is interposed between the second electrode 200 and the second electrode lead 500, so duplicate explanations will be omitted and only the different configurations will be described.

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

[0083] Here, the copper layer has a thickness of approximately 0.5 to 2.0 μm, and the second resin layer is made of polyethylene terephthalate (PET) and has a thickness of approximately 3 to 10 μm, although the thickness is not necessarily limited to this.

[0084] Of course, any material that has high conductivity and does not cause chemical changes in the battery, such as stainless steel, can be used instead of copper.

[0085] The second electrode active material layer 213 is provided on each of the upper and lower surfaces of the pair of copper layers 211 that are exposed to the outside, and the description of these second electrode active materials will be omitted as they have been described above.

[0086] FIG. 13 is a top view of a secondary battery electrode assembly according to a fourth embodiment of the present invention, and FIG. 14 is a bottom view of the secondary battery electrode assembly according to the fourth embodiment of the present invention.

[0087] 10 to 14, the electrical connection structure of the second electrode tab 220, the second electrode lead 500, and the second metal foil 700 will be described.

[0088] Generally, the second electrode tab is made of only metal and can be connected to the second electrode lead by ultrasonic welding, etc. However, as described above, the second electrode current collector and second electrode tab according to the fourth embodiment of the present invention have a structure in which a second resin layer is interposed between a pair of copper layers. That is, due to the second resin layer 212 located at the center of the second electrode tab 220 in the thickness direction (y-axis direction), it is difficult to firmly fix the multiple second electrode tabs 220 to the second electrode lead 500 using ultrasonic welding, and it is also difficult to electrically connect each second electrode tab 220 to the second electrode lead 500.

[0089] Therefore, in the fourth embodiment of the present invention, the second cutting lines 221 are formed in the longitudinal direction (x-axis direction) of the second electrode tab 220, while the second metal foil 700 is disposed so as to pass through the second cutting lines 221.

[0090] More specifically, two second incision lines 221 are provided along the longitudinal direction (x-axis direction) of the second electrode tab 220, spaced apart at a regular interval and parallel to each other.

[0091] Here, it is preferable that both ends of the second cutting line 221 are positioned inside the second electrode tab 220 so that the second metal foil 700 passing through the second cutting line 221 does not come off.

[0092] After the second metal foil 700 passes through one of the two second incision lines 221, it passes through the other second incision line 221, and the second metal foil 700 is exposed from both edges of the second electrode tab 220 in the width direction (z-axis direction) (see Figure 13).

[0093] Meanwhile, the second metal foil 700 is not exposed from both edges in the width direction (z-axis direction) of the rear surface of the second electrode tab 220, but the central portion is exposed (see FIG. 14).

[0094] As a result, the second metal foil 700 has a ribbon shape passing through the two second incision lines 221 in a zigzag pattern, and the second electrode tabs 220 form a single tab bundle by the second metal foil 700 .

[0095] The second electrode lead 500 is then brought into close contact with a portion of the second electrode tab 220 and a portion of the second metal foil 700, and then fixed thereto by ultrasonic welding.

[0096] Here, it is preferable that the second electrode lead 500 faces the surface of the second metal foil 700 exposed from both edges in the width direction (z-axis direction) of the second electrode tab 220. This is because joining and fixing both edges in the width direction (z-axis direction) of the second electrode tab 220 to the second electrode lead 500 is more effective in suppressing loose movement in the width direction (z-axis direction).

[0097] Of course, the second metal foil 700 penetrates the side of the second electrode tab 220, that is, the second incision line 221, so that the second electrode tab 220, the second metal foil 700, and the second electrode lead 500 are electrically connected to one another.

[0098] It is preferable that the width (z-axis direction) of the second metal foil 700 does not exceed the width of the second electrode tab 220, and the length (x-axis direction) of the second metal foil 700 is slightly shorter than the length of the second incision line 221.

[0099] On the other hand, the second metal foil 700 is preferably made of copper, nickel-coated copper, or a nickel-copper alloy that is the same as or similar to the copper layer 211, but can be modified as long as it can perform the same function, and the second electrode lead 500 is made of copper or nickel material, but is not necessarily limited to this.

[0100] For example, although not shown in the drawings, the structure for connecting the second electrode tab, the second electrode lead, and the second metal foil to one another may be the same as that of the second or third embodiment described above.

[0101] Furthermore, the secondary battery electrode assembly may be a combination of the first to fourth embodiments described above.

[0102] The present invention may also be a battery cell including the above-described secondary battery electrode assembly, a battery module or battery pack including the battery cell, or a battery pack including the battery module.

[0103] Although specific parts of the present invention have been described in detail above, it will be apparent to those skilled in the art that such specific techniques are merely preferred embodiments and do not limit the scope of the present invention. It is clear to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it goes without saying that such changes and modifications also fall within the scope of the appended claims. [Explanation of symbols]

[0104] 100 1st electrode 110 First electrode current collector 111 Aluminum layer 112 1st resin layer 113 First electrode active material layer 120 First electrode tab 121 First incision line 200 2nd electrode 210 Second electrode current collector 211 Copper layer 212 2nd resin layer 213 Second electrode active material layer 220 Second electrode tab 221 Second incision line 300 Separation membrane 400 First electrode lead 500 Second electrode lead 600 First Metal Foil 700 Second metal foil

Claims

1. one or more first electrodes including a first electrode current collector and a first electrode tab extending in one direction from the first electrode current collector; one or more second electrodes including a second electrode current collector and a second electrode tab 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 tab; a second electrode lead electrically connected to the second electrode tab; the first electrode current collector has a first resin layer interposed between a pair of aluminum layers, a first metal foil is interposed in at least a portion of an overlapping area between the first electrode tab and the first electrode lead;

2. Two or more first incision lines are provided inside the first electrode tab, the first incision lines being spaced apart at regular intervals in a longitudinal direction, 2. The secondary battery electrode assembly of claim 1, wherein the first metal foil passes through the first incision line, and both ends of the first metal foil are exposed on one side of the first electrode tab, while a central portion of the first metal foil is exposed on the other side of the first electrode tab.

3. 3. The electrode assembly of claim 2, wherein the first electrodes are plural, and one of the first metal foils passes through the first cut line of the first electrode tab.

4. 3. The secondary battery electrode assembly of claim 2, wherein the first electrodes and the first metal foils are plural and equal in number, and one first metal foil passes through the first cut line of one first electrode tab.

5. The electrode assembly of claim 4 , wherein the width of the first metal foil is greater than the width of the first electrode tab in the width direction.

6. The secondary battery electrode assembly of claim 2 , wherein the first electrode lead is positioned to be in close contact with one surface of the first electrode tab where both ends of the first metal foil are exposed.

7. The secondary battery electrode assembly according to claim 2 , wherein the first metal foil comprises aluminum.

8. 3. The secondary battery electrode assembly according to claim 2, wherein the first electrode tab, the first electrode lead, and the first metal foil are fixed to one another by ultrasonic welding.

9. The secondary battery electrode assembly of claim 2 , wherein the first resin layer is polyethylene terephthalate (PET).

10. the second electrode current collector has a second resin layer interposed between a pair of copper layers, The secondary battery electrode assembly according to claim 1 , wherein a second metal foil is interposed in at least a portion of an overlapping area between the second electrode tab and the second electrode lead.

11. Two or more second incision lines are provided inside the second electrode tab at regular intervals in a longitudinal direction, 11. The secondary battery electrode assembly of claim 10, wherein the second metal foil passes through the second incision line, and both ends of the second metal foil are exposed on one side of the second electrode tab, while a central portion of the second metal foil is exposed on the other side of the second electrode tab.

12. 12. The electrode assembly of claim 11, wherein the second electrode is a plurality of second electrodes, and one of the second metal foils passes through the second cut line of the second electrode tab.

13. 12. The secondary battery electrode assembly of claim 11, wherein the second electrodes and the second metal foils are plural and equal in number, and one second metal foil passes through the second incision line of one second electrode tab.

14. The electrode assembly of claim 13 , wherein the width of the second metal foil is greater than the width of the second electrode tab in the width direction.

15. The secondary battery electrode assembly of claim 11 , wherein the second electrode lead is positioned to be in close contact with one surface of the second electrode tab from which both ends of the second metal foil are exposed.

16. The secondary battery electrode assembly of claim 11 , wherein the second metal foil comprises copper, nickel-coated copper, or a nickel-copper alloy.

17. The secondary battery electrode assembly according to claim 11 , wherein the second electrode tab, the second electrode lead, and the second metal foil are fixed to one another by ultrasonic welding.

18. The secondary battery electrode assembly of claim 11, wherein the second resin layer is made of polyethylene terephthalate (PET).

19. A battery cell comprising the secondary battery electrode assembly according to any one of claims 1 to 18.

20. A battery module comprising the battery cell of claim 19.

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