Electrode assembly, battery cell including same, and electrode lead welding method

Abstract

The present invention relates to an electrode assembly, a battery cell including same, and an electrode lead welding method. The electrode assembly according to an embodiment of the present invention includes: a plurality of electrodes; a plurality of electrode tabs which each include a pair of metal layers arranged on the outermost portions and a non-metal layer disposed between the pair of metal layers, and which are connected to the plurality of electrodes; a through portion formed through the plurality of electrode tabs; electrode leads coupled to the electrode tabs; and additional metal layers disposed on the outer surfaces of the outermost electrode tabs disposed at the outermost portions among the plurality of electrode tabs, so as to cover the through portion.

Description

Electrode assembly, battery cell including same, and electrode lead welding method

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0183650, filed December 15, 2023, and Korean Patent Application No. 10-2024-0080414, filed June 20, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to an electrode assembly, a battery cell including the same, and a method for welding electrode leads.

[0005] In recent years, rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution have made the demand for eco-friendly alternative energy sources essential for future living. Research is continuing into various power generation technologies, such as solar, wind, and tidal power. Furthermore, significant interest is being focused on power storage devices, such as batteries, to more efficiently utilize the generated electricity.

[0006] Moreover, with the development of technology and increasing demand for battery-powered electronic mobile devices and battery-powered automobiles, the demand for batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on batteries that can meet various needs.

[0007] Batteries are attracting significant attention as an energy source for a variety of products, including mobile devices and electric vehicles. Secondary batteries, in particular, are an excellent energy source that can replace the use of existing fossil fuel-powered products. They are also gaining recognition as an eco-friendly energy source, as they produce no byproducts from energy use.

[0008] Meanwhile, secondary batteries are also attracting attention as a power source for electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), which are being proposed as solutions to address air pollution issues caused by conventional gasoline and diesel vehicles that use fossil fuels. Specifically, these secondary batteries are utilized in battery packs containing multiple battery modules.

[0009] Secondary batteries include anodes and cathodes, which are laminated with a separator between them to form an electrode assembly. Each anode and cathode has an electrode tab, and since multiple anodes and multiple cathodes have electrode tabs, a plurality of electrode tabs are formed. These multiple electrode tabs are electrically connected to electrode leads. Conventionally, electrode tabs were made of metal. Recently, electrode tabs have begun to be manufactured from materials other than metal. A representative example is metallized films, which deposit metal on a non-metallic material, specifically a polymer layer.

[0010] In the case of metallized films, conventional welding methods between electrode tabs and electrode leads have been problematic, with insufficient fusion strength or partial detachment, leading to defects in the secondary battery assembly process. Furthermore, when physically perforating metallized films, the film's elastic nature creates residue.

[0011] The present invention has been devised to solve the above problems, and the object of the present invention is to provide an electrode assembly capable of forming a penetration portion in an electrode tab formed in a multilayer structure, including an additional metal layer capable of covering the penetration portion, thereby securing an electrical connection between the electrode tabs and improving the weldability of the electrode tab and the electrode lead, and a battery cell and an electrode lead welding method including the same.

[0012] An electrode assembly according to one embodiment of the present invention may include a plurality of electrodes; a pair of metal layers disposed at the outermost portions, and a non-metal layer disposed between the pair of metal layers, each of which includes a plurality of electrode tabs connected to the plurality of electrodes; a through-hole formed through the plurality of electrode tabs; an electrode lead coupled to the electrode tabs; and an additional metal layer disposed on an outer surface of an outermost electrode tab disposed at the outermost portion of the plurality of electrode tabs to cover the through-hole.

[0013] The above electrode lead may be bonded to the outer surface of one outermost electrode tab, and the additional metal layer may be bonded to the outer surface of the other outermost electrode tab.

[0014] The electrode lead may be coupled between the plurality of electrode tabs, and the additional metal layer may include a first additional metal layer coupled to an outer surface of one outermost electrode tab; and a second additional metal layer coupled to an outer surface of another outermost electrode tab.

[0015] The additional metal layer may include a metal having relatively weaker rigidity than the metal layer.

[0016] The above penetration portion may be formed in multiple pieces.

[0017] An electrode assembly according to another embodiment of the present invention may further include a metal member positioned within the penetration portion.

[0018] A portion of the above additional metal layer has the characteristic of flowing into the interior of the penetration portion.

[0019] The metal layer may include aluminum, and the non-metal layer may include a polymer.

[0020] The additional metal layer may include an inner cover portion covering the inner surface of the penetration portion; and an outer cover portion connected to the first cover portion and covering the outer surface of the outermost electrode tab.

[0021] The above inner cover portion can be sunken into the inside of the penetration portion.

[0022] The inner cover portion may include an electrode tab connection portion extending from the outer cover portion to the inside of the penetration portion and conducting current with at least some of the plurality of electrode tabs; and an electrode lead connection portion located on the bottom surface of the penetration portion and conducting current with the electrode tab connection portion and the electrode lead.

[0023] According to one embodiment of the present invention, a battery cell includes an electrode assembly; and a battery case in which the electrode assembly is accommodated, wherein the electrode assembly may include a plurality of electrodes; a pair of metal layers disposed at the outermost portions, and a non-metal layer disposed between the pair of metal layers, each of which includes a plurality of electrode tabs connected to the plurality of electrodes; a through-hole formed through the plurality of electrode tabs; an electrode lead coupled to the electrode tabs; and an additional metal layer disposed on an outer surface of an outermost electrode tab disposed at the outermost portion of the plurality of electrode tabs to cover the through-hole.

[0024] An electrode lead welding method according to one embodiment of the present invention can weld a plurality of electrode tabs and electrode leads.

[0025] The step of assembling the plurality of electrode tabs; the electrode lead welding method may include the step of forming a penetration in the plurality of electrode tabs in a direction in which the plurality of electrode tabs are stacked; the step of disposing an additional metal layer on an outer surface of one outermost electrode tab; the step of disposing the electrode lead on an outer surface of another outermost electrode tab; and the step of welding the electrode tab and the electrode lead.

[0026] In the step of welding the electrode lead, it may be characterized in that a portion of the additional metal layer melts and flows into the penetration portion.

[0027] In the step of placing the electrode lead, the electrode lead may be placed so that at least a portion thereof overlaps with the penetration portion in the stacking direction of the electrode tab.

[0028] In the step of forming a penetration portion in the above electrode tab, the penetration portion may be formed by perforation by a laser.

[0029] The electrode assembly, battery cell including the same, and electrode lead welding method according to the present invention form a penetration hole in an electrode tab formed in a multilayer structure, thereby enabling the electrical connection of multiple electrode tabs. By placing an additional metal layer over the penetration hole, problems that may arise due to the inflow of foreign substances into the penetration hole are prevented. Furthermore, by forming the penetration hole in the electrode tab using a laser, the formation of additional residue is prevented.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0031] Figure 1 is a perspective view of a battery cell according to the present invention.

[0032] FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1 of a battery cell according to one embodiment of the present invention.

[0033] Figure 3 is a cross-sectional view of the electrode tab illustrated in Figure 2.

[0034] Figure 4 is a schematic diagram showing that a through hole is formed in the electrode tab illustrated in Figure 2.

[0035] Figure 5 is an enlarged view of part A of Figure 2.

[0036] FIG. 6 is a cross-sectional view taken along line A-A' of FIG. 1 of a battery cell according to another embodiment of the present invention.

[0037] Figure 7 is an enlarged view of part B of Figure 6.

[0038] FIG. 8 is a schematic diagram illustrating a metal member positioned in a penetration portion of an electrode tab according to another embodiment of the present invention.

[0039] FIG. 9 is a cross-sectional view taken along line A-A' of FIG. 1 of a battery cell according to another embodiment of the present invention.

[0040] Figure 10 is a flowchart of an electrode lead welding method according to one embodiment of the present invention.

[0041] FIGS. 11 and 12 are schematic diagrams illustrating an electrode lead welding method according to one embodiment of the present invention in which an additional metal layer is disposed on the outer surface of the outermost electrode tab.

[0042] FIG. 13 is a schematic diagram illustrating an electrode tab and an electrode lead being welded by a welding device in an electrode lead welding method according to one embodiment of the present invention.

[0043] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0044] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0045] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0046]

[0047] Electrode assembly and battery cell including same

[0048] Hereinafter, the battery cell (1) and electrode lead (14) of the present invention will be described in detail with reference to FIGS. 1 to 9.

[0049] FIG. 1 is a perspective view of a battery cell according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A' of the battery cell illustrated in FIG. 1 according to an embodiment, FIG. 3 is a cross-sectional view of an electrode tab illustrated in FIG. 2, and FIG. 4 is a schematic diagram illustrating a through hole formed in the electrode tab illustrated in FIG. 2. FIG. 5 is an enlarged view of part A of FIG. 2, FIG. 6 is a cross-sectional view taken along line A-A' of the battery cell illustrated in FIG. 1 according to another embodiment, FIG. 7 is an enlarged view of part B of FIG. 6, and FIG. 8 is a schematic diagram illustrating a metal member positioned in a through hole in an electrode tab according to another embodiment of the present invention. FIG. 9 is a cross-sectional view taken along line A-A' of FIG. 1 of a battery cell according to another embodiment of the present invention.

[0050] Referring to FIG. 2, a battery cell (1) may include an electrode assembly (10) and a battery case (20).

[0051] The electrode assembly (10) may include a plurality of electrodes (11), electrode tabs (12), penetrations (13), electrode leads (14), and additional metal layers (15). The electrode assembly (10) may be formed by stacking a plurality of electrodes (11).

[0052] An electrode assembly (10) can be accommodated in a battery case (20). An electrolyte can be accommodated in the battery case (20). When the electrode assembly (10) is accommodated inside the battery case (20) of the battery cell (1), an electrolyte can be injected so that the electrolyte can permeate the electrode assembly (10). The battery case (20) can be formed from a pouch-shaped material. The battery case (20) can be formed to be sealed and blocked from the outside. The battery case (20) can be formed by a forming process of a pouch-shaped material.

[0053] The plurality of electrodes (11) may be positive or negative. The electrodes (11) may be alternately stacked with a separator in between. The separator may be formed longer than the electrodes (11). As described above, the electrodes (11) can be permeated with an electrolyte, and ions within the electrodes (11) can move through the electrolyte.

[0054] The electrode tab (12) can be connected to a plurality of electrodes (11). The electrode tab (12) can be electrically connected to the electrode (11). The electrode tab (12) can be a positive tab or a negative tab. The positive tab can be connected to the positive electrode, and the negative tab can be connected to the negative electrode. Since the electrode tabs (12) are each connected to a plurality of electrodes (11), a plurality of electrode tabs can be formed. A penetration portion (13) can be formed in the electrode tab (12). The electrode tabs (12) can be formed so that they are all electrically connected.

[0055] The electrode tab (12) may include a pair of metal layers (121) and a non-metal layer (122). The electrode tab (12) may be formed by depositing a metal layer (121) on both sides of the non-metal layer (122). The thickness of the metal layer (121) may be formed to be thinner than the thickness of the non-metal layer (122).

[0056] The electrode tab (12) may be composed of a metallized film. The metallized film forms a multilayer structure and is formed by depositing a metal layer (121) on a non-metal layer (122), and has the advantage of being lighter than a conventional film using only metal. The non-metal layer (122) may include a polymer. The metal layer (121) may include aluminum or copper. In the case of an anode electrode tab, the metal layer (121) may be aluminum. In the case of a cathode electrode tab, the metal layer (121) may be copper.

[0057] The penetration portion (13) may be formed to penetrate the electrode tab (12). The penetration portion (13) may be formed in multiple numbers. The penetration portion (13) may be formed to completely penetrate the electrode tab (12) in the stacking direction of the electrode tab (12). The penetration portions (13) may be formed to be spaced apart from the electrode tab (12) at a certain interval. A plurality of penetration portions (13) may be formed along the width direction of the electrode tab (12). The penetration portion (13) may be formed in a circular shape, but is not limited thereto.

[0058] In the present invention, when the electrode tab (12) includes a pair of metal layers (121) and non-metal layers (122), electrical connection between the metal layers (121) may not be smooth due to the non-metal layer (122), so that a penetration portion (13) is formed so that electrical connection between the electrode tabs (12) can be maintained.

[0059] Referring to Fig. 8, a metal member (16) may be positioned within the penetration portion (13). As described above, since the electrode tab (12) includes a non-metallic layer (122), a metal member (16) may be positioned within the penetration portion (13) to electrically connect a plurality of electrode tabs (12). The outer diameter of the metal member (16) may be less than or equal to the inner diameter of the penetration portion (13). The metal member (16) may not be a single member but may include metal powder.

[0060] The electrode lead (14) can be coupled to the electrode tab (12). The electrode lead (14) can be electrically connected to the electrode tab (12).

[0061] An additional metal layer (15) may be arranged to cover the penetration portion (13). The additional metal layer (15) may be arranged on the outer surface of the outermost electrode tab (12) arranged at the outermost end of the plurality of electrode tabs (12).

[0062] The additional metal layer (15) may include the same metal as the metal layer (121). The additional metal layer (15) may have the same chemical properties as the metal layer (121) but different physical properties. The additional metal layer (15) may include a metal having a relatively weaker physical property, i.e., rigidity, than the metal layer (121). Since the rigidity is relatively weak, a portion of the additional metal layer (15) may melt and flow into the inside of the penetration portion (13) when welding the electrode lead (14) and the electrode tab (12). Since a portion of the additional metal layer (15) flows into the inside of the penetration portion (13), the electrical connection between the metal layers (121) may be maintained. The additional metal layer (15) also has the effect of covering the penetration portion (13) to prevent problems caused by the introduction of other materials.

[0063] Referring to FIGS. 2, 5, and 10 to 12, in an electrode assembly (10) according to one embodiment of the present invention, an electrode lead (14) may be coupled to an outer surface of one outermost electrode tab (12). The electrode lead (14) may be coupled to an outer surface of one outermost electrode tab (12), and an additional metal layer (15) may be coupled to an outer surface of the other outermost electrode tab (12). Accordingly, the penetration portion (13) may be formed to communicate from one surface of the additional metal layer (15) to one surface of the electrode lead (14).

[0064] Referring to FIGS. 6 and 7, in an electrode assembly (10) according to another embodiment of the present invention, an electrode lead (14) may be coupled between a plurality of electrode tabs (12). The additional metal layer (15) may include a first additional metal layer and a second additional metal layer. In this case, since the first additional metal layer and the second additional metal layer have the same configuration with only the position in which they are arranged being different, the drawing reference numeral of the additional metal layer (15) will be cited.

[0065] The first additional metal layer (15) can be bonded to the outer surface of one outermost electrode tab (12). The second additional metal layer (15) can be bonded to the outer surface of the other outermost electrode tab (12). Accordingly, the electrode lead (14) can be placed between the first additional metal layer (15) and the second additional metal layer (15). Accordingly, the first additional metal layer (15) can be connected to the electrode lead (14) by the through-hole (13), and the electrode lead (14) can be connected to the second additional metal layer (15) by the through-hole (13).

[0066] Hereinafter, with reference to FIG. 9, an electrode tab (12), an electrode lead (14), and an additional metal layer (15) of an electrode assembly according to another embodiment of the present invention will be described. In this embodiment, the electrode tab (12) and the electrode lead (14) may be configured in the same manner as the electrode tab and electrode lead of the electrode assembly described above with reference to FIGS. 2 and 6.

[0067] Referring to Fig. 9, the penetration portion (13) according to the present embodiment may be provided in the form of a hole penetrating a plurality of electrode tabs (12). At this time, the hole may penetrate the plurality of electrode tabs (12) from the electrode tab (12) located at the outermost side to the innermost electrode tab (12) in contact with the electrode lead (14). The inner circumference of such penetration portion (13) may be formed as a cross-section of the plurality of electrode tabs (12).

[0068] In this embodiment, the additional metal layer (15) may include an outer surface cover portion (15a) and an inner surface cover portion (15b). The outer surface cover portion (15a) may cover the outer surface of the outermost electrode tab (12). Here, covering the outer surface of the outermost electrode tab (12) may mean covering an area of ​​the outer surface.

[0069] In this embodiment, the inner cover portion (15b) can extend from the outer cover portion (15a) to the inside of the penetration portion (13). The inner cover portion (15b) can cover the inner surface of the penetration portion (13). As a result, a plurality of electrode tabs (12) forming the inner periphery of the penetration portion (13) can be electrically connected to each other.

[0070] More specifically, the inner cover portion (15b) may include an electrode tab connection portion that covers the inner periphery of the penetration portion (13). The electrode tab connection portion may have a cylindrical shape similar to the inner periphery of the penetration portion. However, the shape of the electrode tab connection portion may be appropriately modified to fit the shape of the penetration portion. By means of such an electrode tab connection portion, a plurality of electrode tabs (12) may be electrically connected to each other.

[0071] In this embodiment, the inner cover portion (15b) may include an electrode lead connection portion positioned on the bottom surface of the penetration portion (13). The bottom surface of the penetration portion (13) may be formed by the outer surface of the electrode lead (14). The electrode lead connection portion may be in contact with the outer surface of the electrode lead (14). In addition, the electrode lead connection portion may be connected to the electrode tab connection portion.

[0072] In this embodiment, the electrode lead connection portion can conduct current between the electrode lead (14) and the electrode tab connection portion. Through this, the electrode lead (14) and the electrode tab (12) can be electrically connected to each other via the inner cover portion (15b).

[0073] Meanwhile, in the present embodiment, the inner cover portion (15b) may be formed by a portion of the additional metal layer (15) covering the outermost electrode tab (12) being sunk into the inside of the penetration portion (13). As an example, the inner cover portion (15b) may be formed by a portion of the additional metal layer (15) being pressed into the inside of the penetration portion (13) by an external force. As another example, the inner cover portion (15b) may be formed by a portion of the additional metal layer (15) being melted and flowing into the penetration portion (13).

[0074] Due to this, a groove (h_15) that is concavely sunken from the additional metal layer (15) toward the electrode lead (14) may be formed in the center of the inner cover portion (15b). Of course, in some cases, since the inner cover portion (15b) entirely fills the penetration portion (13), a separate groove may not be formed in the inner cover portion (15b).

[0075] As described above, according to another embodiment of the present invention, since the inner cover portion (15b) of the additional metal layer (15) conducts current between the electrode lead (14) and the electrode tab (12), the electrical connectivity of the electrode assembly can be more stable and have higher reliability.

[0076]

[0077] Electrode lead welding method

[0078] Hereinafter, an electrode lead welding method according to one embodiment of the present invention will be described in detail with reference to FIGS. 10 to 13.

[0079] FIG. 10 is a flowchart of an electrode lead welding method according to one embodiment of the present invention, FIGS. 11 and 12 are schematic diagrams illustrating an additional metal layer being disposed on the outer surface of an outermost electrode tab in an electrode lead welding method according to one embodiment of the present invention, and FIG. 13 is a schematic diagram illustrating an electrode tab and an electrode lead being welded by a welding device in an electrode lead welding method according to one embodiment of the present invention.

[0080] Referring to FIGS. 10 to 13, an electrode lead welding method according to one embodiment of the present invention can weld a plurality of electrode tabs (12) and electrode leads (14). The electrode lead welding method can include a step (S1) of assembling a plurality of electrode tabs (12).

[0081] In the step (S1) of collecting a plurality of electrode tabs (12), the plurality of electrode tabs (12) can be collected at the center of the direction in which the electrode tabs (12) are stacked. In the step (S1) of collecting the electrode tabs (12), the positive tabs can be collected with the positive tabs and the negative tabs can be collected with the negative tabs.

[0082] The electrode lead welding method may include a step (S2) of forming a penetration portion (13) in a plurality of electrode tabs (12). In the step (S2) of forming a penetration portion in the electrode tab, the penetration portion (13) may be formed by perforation using a laser. When forming a penetration portion (13) in the electrode tab (12), the penetration portions (13) must all be formed so that they are aligned when viewed from the stacking direction of the plurality of electrode tabs (12).

[0083] When forming a penetration portion (13), a circular penetration portion (13) can be formed using a laser. If a physical force is used to perforate the penetration portion (13), residue may be generated due to the stretching properties of the electrode tab (12), and it may be difficult to form the penetration portion (13) in a consistent pattern. Therefore, a laser is used to perforate the penetration portion (13) in a consistent pattern and to remove the residue. In addition, as described above, the electrode tab (12) can be composed of a metallized film, and the metallized film has the characteristic of being easily pierced by a laser. By utilizing this property, the penetration portion (13) can be formed using a laser.

[0084] The electrode lead welding method may include a step (S3) of placing an additional metal layer (15) on the outer surface of an outermost electrode tab (12). The additional metal layer (15) may be placed so as to cover the entire penetration portion (13) of the electrode tab (12).

[0085] The electrode lead welding method may include a step (S4) of placing the electrode lead (14) on the outer surface of the outermost electrode tab (12). In the step (S4) of placing the electrode lead (14), the electrode lead (14) may be positioned so as to overlap at least a portion of the penetration portion (13) in the stacking direction of the electrode tab (12). The electrode lead (14) may be electrically connected to the electrode tab (12) by overlapping at least a portion of the penetration portion (13).

[0086] The electrode lead welding method may include a step (S5) of welding an electrode tab (12) and an electrode lead (14). The electrode tab (12) and the electrode lead (14) may be welded using a welding device (2) in a direction in which the electrode tab (12) and the electrode lead (14) are stacked. The electrode tab (12) and the electrode lead (14) may be welded using ultrasonic waves in the welding device (2).

[0087] It may be characterized in that in the step (S5) of welding the electrode lead, a portion of the additional metal layer (15) is melted and flows into the penetration portion (13). Since the additional metal layer (15) is melted and flows into the penetration portion (13), an electrical connection can be made between a plurality of electrode tabs (12).

[0088] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0089] [Explanation of symbols]

[0090] 1: Battery cell

[0091] 10: Electrode assembly

[0092] 11: Electrode

[0093] 12: Electrode tab

[0094] 121: Metal layer

[0095] 122: Non-metallic layer

[0096] 13: Penetration

[0097] 14: Electrode leads

[0098] 15: Additional metal layer

[0099] 20: Battery case

Claims

1. Multiple electrodes; A plurality of electrode tabs, each comprising a pair of metal layers arranged at the outermost portion and a non-metal layer arranged between the pair of metal layers, and connected to the plurality of electrodes; A penetration formed through the plurality of electrode tabs; an electrode lead coupled with the above electrode tab; and An electrode assembly comprising an additional metal layer arranged on an outer surface of an outermost electrode tab among the plurality of electrode tabs so as to cover the penetration portion.

2. In paragraph 1, The above electrode lead is coupled to the outer surface of one outermost electrode tab, An electrode assembly wherein the above additional metal layer is bonded to the outer surface of the outermost electrode tab.

3. In paragraph 1, The above electrode lead is coupled between the plurality of electrode tabs, The above additional metal layer is, A first additional metal layer bonded to the outer surface of the outermost electrode tab; and An electrode assembly comprising a second additional metal layer bonded to the outer surface of the outermost electrode tab.

4. In paragraph 1, An electrode assembly wherein the additional metal layer comprises a metal having relatively weaker rigidity than the metal layer.

5. In paragraph 1, An electrode assembly further comprising a metal member positioned within the penetration portion.

6. In paragraph 1, An electrode assembly in which the above penetration portions are formed in multiple pieces.

7. In paragraph 1, An electrode assembly characterized in that a portion of the additional metal layer flows into the interior of the penetration portion.

8. In paragraph 1, The above metal layer comprises aluminum, The above non-metallic layer is an electrode assembly comprising a polymer.

9. In paragraph 1, The above additional metal layer is, An inner cover portion covering the inner surface of the above-mentioned penetration portion; and An electrode assembly comprising an outer cover portion connected to the first cover portion and covering an outer surface of the outermost electrode tab.

10. In paragraph 9, The above inner cover portion is an electrode assembly sunk into the inside of the penetration portion.

11. In paragraph 9, The inner cover part above is, An electrode tab connection portion extending from the outer cover portion to the inside of the penetration portion and electrically conducting with at least some of the plurality of electrode tabs; and An electrode assembly, comprising an electrode lead connection portion positioned on the bottom surface of the above penetration portion and conducting current between the electrode tab connection portion and the electrode lead.

12. Electrode assembly; and A battery case is included in which the electrode assembly is accommodated, The above electrode assembly is, multiple electrodes; A plurality of electrode tabs, each comprising a pair of metal layers arranged at the outermost portion and a non-metal layer arranged between the pair of metal layers, and connected to the plurality of electrodes; A penetration formed through the plurality of electrode tabs; an electrode lead coupled with the above electrode tab; and A battery cell comprising an additional metal layer arranged to cover the penetration portion on an outer surface of an outermost electrode tab arranged at the outermost end of the plurality of electrode tabs.

13. In an electrode lead welding method for welding multiple electrode tabs and electrode leads, A step of collecting the plurality of electrode tabs; A step of forming a penetration portion in the plurality of electrode tabs in the direction in which the plurality of electrode tabs are stacked; A step of placing an additional metal layer on the outer surface of an outermost electrode tab; A step of placing the above electrode lead on the outer surface of the outermost electrode tab; and An electrode lead welding method comprising the step of welding the electrode tab and the electrode lead.

14. In paragraph 13, In the step of welding the above electrode leads, An electrode lead welding method characterized in that a portion of the additional metal layer melts and flows into the penetration portion.

15. In paragraph 13, In the step of placing the above electrode leads, An electrode lead welding method, characterized in that the electrode lead is arranged so as to overlap at least a portion of the penetration portion with the stacking direction of the electrode tab.

16. In paragraph 13, In the step of forming a penetration portion in the above electrode tab, An electrode lead welding method in which the above penetration portion is formed by perforation by a laser.

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