Electrode assembly including electrode tabs of metallized film and metal connectors connecting the electrode tabs, and secondary battery including the same

Abstract

The present invention relates to an electrode assembly for a secondary battery including two or more electrodes and one or more separators, wherein the two or more electrodes each include an electrode tab, the electrode tab being made of a metallized film having a metal layer formed on an upper surface and a lower surface of a polymer-based material, the electrode tabs being arranged such that a portion or all of the electrode tabs do not overlap in the stacking direction, and the electrode tabs are electrically connected via a first metal connector on the upper surface on which the metal layer is formed and electrically connected via a second metal connector on the lower surface on which the metal layer is formed, and a secondary battery including the electrode assembly.

Description

[Technical field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0024689 filed on February 24, 2022 and Korean Patent Application No. 10-2023-0010153 filed on January 26, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly including electrode tabs of a metallized film and a metal connector connecting the electrode tabs and a secondary battery including the electrode assembly. [Background technology]

[0003] Along with technological development and increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which exhibit high energy density and working potential, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0004] In addition, in recent years, the design of electronic devices itself has become a very important factor in consumers' product selection, and electronic devices tend to become smaller and thinner according to consumer preferences. As a result, in order to minimize the waste of internal space in electronic devices, lithium secondary batteries are also required to be smaller and thinner, and the demand for them is increasing.

[0005] Among the components of such lithium secondary batteries, electrodes are generally made by forming a cathode active material and an anode active material on one or both sides of a cathode (Al) and an anode (Cu) thin film current collector, and then stacking them in the order of a cathode, a separator, an anode, and a separator to manufacture a battery.

[0006] In recent years, in order to obtain a high energy density, the number of layers is increased, the current collector is made thinner, the electrode active material layer is made thicker, and the rolling strength is increased.

[0007] As a result, as the thickness of the cells increases and the thickness of the current collectors becomes thinner and thinner, the occurrence of disconnection defects in which the current collectors or the tabs protruding therefrom break is increasing.

[0008] In particular, in the case of current collectors and tabs made of aluminum foil, the low elongation rate makes disconnection more critical. To solve this problem, metallized films are used in which metal is vapor-deposited or adhered to films such as polypropylene or polyethylene terephthalate, but in this case, it is difficult to electrically connect multiple layers of metallized films.

[0009] To illustrate this, FIG. 1 shows a conventional electrode assembly 10 and FIG. 2 shows how the metallized film positive electrode tabs 11 of the electrode assembly 10 can be electrically connected to each other.

[0010] 1, a conventional electrode assembly 10 includes a positive electrode, a negative electrode, and a separator, with a positive electrode tab 11 protruding from the positive electrode and a negative electrode tab 12 protruding from the negative electrode. In this case, the positive electrode tab 11 and the negative electrode tab 12 protrude from the same position.

[0011] At this time, the positive electrode tabs 11 are formed in a line when viewed from the front of the electrode assembly 10 as shown in FIG.

[0012] At this time, the positive electrode tab 11 has a structure in which the polymer substrate is located in the center and metal is evaporated or attached to the upper and lower surfaces of the polymer substrate. In order to electrically connect all of these, as shown in FIG. 2(a), a metal rod 13a is inserted through the positive electrode tab 11, or as shown in FIG. 2(b), a metal connector 13b is used to connect them in a zigzag pattern.

[0013] However, in this case, when a defect occurs when the metal rod 13a is penetrated, or when the metal connector 13b is formed in a zigzag pattern, the connection process becomes complicated at the mass production stage, which causes a problem of slowing down the production speed.

[0014] Therefore, there is a need for a technique for quickly and easily electrically connecting electrode tabs of a metallized film that can solve these problems and increase production speed during mass production. Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention aims to provide an electrode assembly having a structure capable of quickly electrically connecting the tabs in mass production while eliminating disconnection defects of the tabs, thereby improving production speed, and a secondary battery including the same. [Means for solving the problem]

[0016] The electrode assembly according to one embodiment of the present invention comprises: An electrode assembly for a secondary battery comprising two or more electrodes and one or more separators, each of the two or more electrodes includes an electrode tab; the electrode tab is made of a metallized film having a metal layer formed on the upper and lower surfaces of a polymer substrate; the electrode tabs are arranged such that a part or the whole of each of the electrode tabs does not overlap in a stacking direction; The electrode tabs are electrically connected via a first metal connector on the upper surface on which the metal layer is formed, and are electrically connected via a second metal connector on the lower surface on which the metal layer is formed.

[0017] Here, the first metal connector and the second metal connector may be additionally electrically connected to each other at a position that does not overlap with the electrode tab.

[0018] Specifically, the first metal connector and the second metal connector may be directly and electrically connected to each other at both ends in the width direction of the electrode assembly.

[0019] In this case, the area where the first metal connector and the second metal connector are connected to each other may be 10% to 50% of the width of the electrode tab.

[0020] The first metal connector and the second metal connector may each have a thickness of 10 μm to 1500 μm.

[0021] The electrical connection between the first metal connector and the second metal connector can be achieved by welding or adhesion.

[0022] Meanwhile, the electrode tabs may be arranged so as not to overlap with each other in the stacking direction.

[0023] Alternatively, each of the electrode tabs may be arranged to at least partially overlap with an adjacent electrode tab in the stacking direction.

[0024] Alternatively, some of the electrode tabs may be arranged so as to at least partially overlap with adjacent electrode tabs in the stacking direction, and the remainder may be arranged so as not to overlap with any electrode tabs in the stacking direction. That is, the electrode tabs may have exposed portions in a stepped shape.

[0025] However, in any case, it is preferable that the area of ​​one or more metal connectors selected from the first metal connector and the second metal connector that is electrically connected to each electrode tab is 50% or more of the total area of ​​each of the electrode tabs.

[0026] In addition, the electrode tabs may be entirely covered at the top and bottom by the first metal connector and the second metal connector.

[0027] The polymer-based material constituting such an electrode tab may have a thickness of 3 μm to 20 μm, and each of the metal layers may have a thickness of 0.2 μm to 3 μm.

[0028] Specifically, the polymer substrate may be made of one or more materials selected from polyolefin (PO), polyethylene terephthalate (PET), and cellulose.

[0029] The metal layer may also be made of one or more materials selected from Ni, Cu, Al, and stainless steel.

[0030] Meanwhile, the first metal connector and the second metal connector may each be made of one or more materials selected from Ni, Cu, Al, and stainless steel.

[0031] In particular, the first metal connector, the second metal connector, and the metal layer of the electrode tab may be made of the same material.

[0032] In the electrode assembly of the present invention, one or more selected from the first metal connector and the second metal connector may be connected to an electrode lead, instead of the electrode tab.

[0033] Meanwhile, according to yet another embodiment of the present invention, there is provided a secondary battery including the electrode assembly. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a perspective view showing a schematic diagram of a conventional electrode assembly. [Diagram 2] 1 is a schematic diagram showing a state in which an electrode tab of a conventional electrode assembly is connected to a metal connector; [Diagram 3] 1 is a perspective view illustrating an electrode assembly according to an embodiment of the present invention; [Figure 4] 4 is a schematic diagram showing a state in which an electrode tab of the electrode assembly of FIG. 3 is connected to a metal connector. FIG. [Diagram 5] 2A and 2B are schematic diagrams illustrating a configuration of an electrode tab according to an embodiment of the present invention. [Figure 6]13 is a schematic diagram showing a form in which an electrode tab is connected to a metal connector in still another embodiment of the present invention. FIG. [Figure 7] 13 is a schematic diagram showing a form in which an electrode tab is connected to a metal connector in still another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The terms and words used in the present specification and claims should not be interpreted in the usual dictionary sense, but should be interpreted in the sense and concept consistent with the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term in order to best describe his invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention and do not fully represent the technical idea of ​​the present invention, and therefore, at the time of filing this application, there may be various equivalents and modifications that can replace them, and the scope of the present invention is not limited to the embodiments described below.

[0036] The present invention will be described in detail below with reference to the drawings and examples. The terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his / her invention.

[0037] Furthermore, it should be understood that the embodiments described in the following specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore there are various equivalents and modifications that can replace them at the time of this application.

[0038] Furthermore, since the drawings are created without distinguishing between positive and negative electrodes, the same names may be used, and even if the names are the same, they are distinguished by reference symbols.

[0039] According to one embodiment, the present invention comprises: An electrode assembly for a secondary battery comprising two or more electrodes and one or more separators, each of the two or more electrodes includes an electrode tab; the electrode tab is made of a metallized film having a metal layer formed on the upper and lower surfaces of a polymer substrate; the electrode tabs are arranged such that a part or the whole of each of the electrode tabs does not overlap in a stacking direction; An electrode assembly is provided in which the electrode tabs are electrically connected via a first metal connector on the upper surface on which the metal layer is formed, and are electrically connected via a second metal connector on the lower surface on which the metal layer is formed.

[0040] In order to specifically explain the connection structure between the electrode tab and the metal connector in the present invention, reference will be made to Figs. 3 to 5. Figs.

[0041] Specifically, FIG. 3 is a schematic perspective view of an electrode assembly according to one embodiment of the present invention, FIG. 4 is a schematic view of, for example, a connection structure between an electrode tab and a metal connector, and FIG. 5 is a schematic view of the structure of an electrode tab.

[0042] Referring to FIG. 3, an electrode assembly 100 according to an embodiment of the present invention includes two or more electrodes and one or more separators, and the two or more electrodes have a structure including electrode tabs 101 and 102, respectively.

[0043] Electrode tab 101 is an electrode tab extending from a first electrode, and electrode tab 102 is an electrode tab extending from a second electrode.

[0044] At this time, the electrode tabs 101, 102 are arranged so that they are each exposed in the stacking direction, and the electrode tab 101 is electrically connected via a metal connector 110 composed of a first metal connector 111 and a second metal connector 112, and the electrode tab 102 is electrically connected via a metal connector 120 composed of a first metal connector 121 and a second metal connector 122.

[0045] Here, in order to consider the connection structure between the electrode tabs 101, 102 and the metal connectors 110, 120 in more detail, reference will be made to FIG. 4 as well as FIG. 5 which shows the structure of the electrode tab 101. FIG.

[0046] FIG. 4 shows a representative connection structure between an electrode tab 101 and a metal connector 110, and FIG.

[0047] 3 to 5, the electrode tab 101 of the present invention is composed of a metallized film having metal layers 101b, 101c formed on the upper and lower surfaces of a polymer base material 101a, and the electrode tab 101 is electrically connected via a first metal connector 111 on the upper surface where the metal layer 101b is formed, and is electrically connected via a second metal connector 112 on the lower surface where the metal layer 101c is formed.

[0048] In addition, the first metal connector 111 and the second metal connector 112 have a structure in which they are directly electrically connected to each other at positions that do not overlap with the electrode tabs 101, more specifically, at both ends in the width direction of the electrode assembly 100, i.e., in the direction in which the electrode tabs 101 are arranged.

[0049] In this case, the area where first metal connector 111 and second metal connector 112 are connected to each other may be 10% to 50% of the width of electrode tab 101.

[0050] As described above, the electrode tab 101 according to the present invention has a structure in which the metal layers 101b, 101c are formed on the upper and lower surfaces of the polymer-based material 101a. Therefore, the metal layer 101b on the upper surface and the metal layer 101c on the lower surface are not electrically connected to each other. Therefore, unless these are connected to each other, electrical connection of the electrodes cannot be achieved. Therefore, the first metal connector 111 requires not only the first metal connector 111 connected to the upper surface, but also the second metal connector 112 connected to the lower surface, and the first metal connector 111 and the second metal connector 112 must have a structure in which they are electrically connected to each other.

[0051] Therefore, the area where the first metal connector 111 and the second metal connector 112 are connected affects the amount and effect of current flow through the electrode tabs. Therefore, if these connections are made over too small an area beyond the above range, the conductivity decreases, and if the connections are made over too large an area, the volume increases more than necessary, which is not preferable.

[0052] On the other hand, the thickness of each of first metal connectors 111 and second metal connectors 112 may be 10 μm to 1500 μm, more specifically 50 μm to 800 μm, and even more specifically 80 μm to 700 μm.

[0053] If the thickness is too thin beyond the above range, disconnection may occur even in the metal connector, and if the thickness is too thick, the overall volume may increase, which is undesirable.

[0054] In addition, the metal connectors 110, 120 may each be made of one or more materials selected from Ni, Cu, Al, stainless steel, alloys thereof, and materials obtained by coating these metals with carbon or coating them with a dissimilar metal. More specifically, the metal connectors 110, 120 may each be made of one or more materials selected from Ni, Cu, Al, and stainless steel. Most specifically, the metal connectors 110, 120 may each be appropriately selected in consideration of the metal layers contained in the electrode tabs 101, 102 to which they are connected.

[0055] In the above, the electrical connections of the metal connectors 110, 120, the respective electrode tabs 101, 102, and the first metal connector 111 and the second metal connector 112, etc. are not limited to any particular method as long as only electrical connections are made, and may be made by, for example, welding or adhesion, and more specifically, may be made by ultrasonic welding or laser welding, etc.

[0056] On the other hand, the polymer-based material 101a constituting the electrode tab 101 may have a thickness of 3 μm to 20 μm, and more specifically, may have a thickness of 6 μm to 12 μm.

[0057] If the thickness exceeds the above range and is too thin, breakage or tearing may occur, whereas if the thickness is too thick, the electrical conductivity may decrease, which is undesirable.

[0058] Such a polymer substrate is not limited as long as it is chemically resistant to the electrolyte and does not cause chemical problems when used in a battery. For example, the polymer substrate may be made of one or more selected from polyolefin (PO), polyethylene terephthalate (PET), and cellulose, and more particularly, may be made of polypropylene (PP) or polyethylene terephthalate (PET).

[0059] Moreover, the metal layers 101b and 101c may each have a thickness of 0.2 μm to 3 μm, and more specifically, a thickness of 0.5 μm to 2 μm.

[0060] If the thickness exceeds the range, the conductivity may decrease if the thickness is too thin, whereas if the thickness is too thick, the volume of the electrode tab may decrease, which is undesirable.

[0061] The metal layers 101b and 101c may be made of one or more materials selected from Ni, Cu, Al, stainless steel, alloys thereof, and materials obtained by coating these metals with carbon or coating them with a dissimilar metal, more particularly, they may be made of one or more materials selected from Ni, Cu, Al, and stainless steel, and most particularly, they may be made of the same material as the metal connector 110 among the above metals.

[0062] In the above drawings, electrode tabs 101 and 102 are shown as being made of metallized films and electrically connected by metal connectors 110 and 120, but it is of course possible for only one of them to have the configuration of the present application.

[0063] On the other hand, such metallized films have an overwhelmingly higher elongation rate and bending rate than metal tabs, and are therefore free from the commonly occurring problems of disconnection.

[0064] However, due to the structure, a polymer base material is interposed between the tabs, and so there is a problem that electrical connection between the tabs cannot be achieved by welding or fusing the tabs to the leads all at once, as with conventional tabs.

[0065] As explained above, conventionally, electrical connections between the tabs are made as shown in FIG. 2, but this has the problem of slowing down the production speed during mass production.

[0066] Therefore, the inventors of the present application have studied a method for solving the above problems and for electrically connecting electrode tabs at once in a similar manner to the conventional method, and have completed the present invention.

[0067] For this purpose, the electrode tabs may be arranged so that they are all exposed in the stacking direction.

[0068] At this time, the electrode tabs may or may not overlap, and there is no limitation thereto.

[0069] In order to explain such an arrangement structure of the electrode tabs, reference will be made to FIGS.

[0070] FIG. 4 is as described above, and FIGS. 6 and 7 are schematic diagrams showing a state in which an electrode tab according to still another embodiment of the present invention is connected to a metal connector.

[0071] 4, for example, the electrode tabs 101 may be arranged so as not to overlap each other in the stacking direction, with the electrode tabs 101 being the same size. Therefore, when viewed from the front, the electrode tabs 101 are arranged in parallel in a line, and the metal connectors 110 may electrically connect them at the top and bottom.

[0072] Alternatively, as another example, referring to Figures 6 and 7, each electrode tab 201, 301 can be arranged so as to at least partially overlap with an adjacent electrode tab in the stacking direction, and these can be electrically connected to the electrode tabs by metal connectors 210, 310, specifically, first metal connectors 211, 311 on the upper surface and second metal connectors 212, 312 on the lower surface, and the first metal connectors 211, 311 and second metal connectors 212, 312 can be welded or bonded to each other.

[0073] In this case, the overlapping shape may be such that the electrode tabs 201 and 301 have surfaces exposed in the stacking direction and are arranged to overlap at least partially, so that they have stepped exposed portions.

[0074] However, as long as adjacent electrode tabs partially overlap, the shape is not limited to that shown in FIGS. 6 and 7, and various modifications are possible.

[0075] Although not shown in the drawings, some of the electrode tabs may be arranged so as to at least partially overlap adjacent electrode tabs in the stacking direction, and the remainder may be arranged so as not to overlap any electrode tab in the stacking direction.

[0076] However, in any case, it is preferable that the area electrically connected to each electrode tab of one or more metal connectors selected from the first metal connector and the second metal connector 112 is 50% or more of the total area of ​​each electrode tab. That is, it is preferable that the area in direct contact between the electrode tab and one or more metal connectors selected from the first metal connector and the second metal connector 112 is 50% or more.

[0077] Specifically, referring to FIG. 4 again, all of the electrode tabs 101 are electrically connected to the first metal connector 111 and the second metal connector 112 over 100% of the area. Meanwhile, referring to FIG. 5, the electrode tab located at the top of the electrode tabs 201 is electrically connected to the first metal connector 211 over 100% of the area, and the electrode tabs located from the second to fourth positions are connected to the first metal connector 211 and the second metal connector 212 over 50% or more of the area. Also, referring to FIG. 6, the electrode tab located at the top of the electrode tabs 301 is electrically connected to the first metal connector 311 over 100% of the area, the electrode tabs located at the second and third positions are connected to the first metal connector 211 over 50% or more of the area, and the electrode tab located at the bottom is connected to the first metal connector 311 over 50% or less of the area, but is connected to the second metal connector 312 over 100% of the area.

[0078] Furthermore, in any case, as shown in Figs. 4 to 6, it is preferable that each of the electrode tabs is entirely covered at the top and bottom by the first metal connector and the second metal connector.

[0079] As a result, the electrode tabs are not exposed to the outside, but are entirely covered by the metal connector, thereby improving electrical conductivity.

[0080] In the above configuration, in consideration of the manufacturing process of the electrode tabs, economic efficiency, resistance during welding, and the like, it is most preferable to manufacture the electrode tabs in the form of FIG. 4 so that the electrode tabs are formed to the same size, the overall thickness is the same at any electrode tab formation position, and the intended effect of the present application can be achieved using the smallest amount.

[0081] Furthermore, according to the present invention, it is possible to realize electrical connection of the entire electrode to an external element simply by connecting an electrode lead to one or more selected from the first metal connector and the second metal connector.

[0082] Meanwhile, the present invention further provides a secondary battery including the electrode assembly according to one embodiment.

[0083] Specifically, the electrode assembly is housed in a secondary battery case together with an electrolyte.

[0084] Specifically, the secondary battery is a lithium secondary battery.

[0085] Other components of the lithium secondary battery are well known in the art, so a description of them will be omitted in this specification.

[0086] Those skilled in the art will appreciate that the present invention can be applied in various ways and modified within the scope of the present invention based on the above content. [Industrial Applicability]

[0087] The electrode assembly according to the present invention uses a metallized film having metal layers formed on the upper and lower surfaces of a polymer-based material as an electrode tab, thereby solving the problem of tab breakage, and by arranging the electrode tabs in parallel so that they are exposed in the stacking direction, the electrode tabs can be electrically connected in a simple manner using a metal connector, thereby significantly improving the production speed in mass production. [Explanation of symbols]

[0088] 100 Electrode Assembly 101 Electrode tab 101a Polymer base material 101b Metal layer 101c metal layer 102 Electrode tab 110 Metal connector 111 First metal connector 112 Second metal connector 120 Metal connector 121 First metal connector 122 Second metal connector 201 Electrode tab 210 Metal connector 211 First metal connector 212 Second metal connector 301 Electrode tab 310 Metal connectors 311 First metal connector 312 Second metal connector

Claims

1. An electrode assembly for a secondary battery comprising two or more electrodes and one or more separators, each of the two or more electrodes includes an electrode tab; Each of the electrode tabs is made of a metallized film having a metal layer formed on the upper and lower surfaces of a polymer substrate, the electrode tabs of the same polarity are arranged such that a part or the whole of each of the electrode tabs does not overlap in a stacking direction of the electrodes; The electrode assembly includes a first metal connector disposed on an upper surface side of the electrode tab and a second metal connector disposed on a lower surface side of the electrode tab, the electrode tabs of the same polarity are electrically connected to each other via the first metal connector on the upper surface on which the metal layer is formed, and are electrically connected to each other via the second metal connector on the lower surface on which the metal layer is formed; the electrode tab and the first metal connector are connected to each other at a portion of an upper surface of the electrode tab that is exposed when viewed from the upper surface side in the stacking direction, an electrode assembly, wherein the electrode tab and the second metal connector are connected at a portion of a lower surface of the electrode tab that is exposed when viewed from the lower surface side in the stacking direction;

2. The electrode assembly of claim 1 , wherein the first metal connection body and the second metal connection body are additionally electrically connected to each other at a position that does not overlap the electrode tab.

3. The electrode assembly according to claim 2 , wherein the first metal connector and the second metal connector are directly electrically connected to each other at both ends in a width direction of the electrode assembly.

4. 3. The electrode assembly according to claim 2, wherein an area where the first metal connector and the second metal connector are connected to each other is 10% to 50% of a width of the electrode tab.

5. The electrode assembly according to claim 1 , wherein the first metal connector and the second metal connector each have a thickness of 10 μm to 1500 μm.

6. The electrode assembly according to any one of claims 1 to 4, wherein the electrical connection between the first metal connector and the second metal connector is performed by welding or bonding.

7. The electrode assembly according to claim 1 , wherein the electrode tabs are arranged so as not to overlap each other in the stacking direction.

8. The electrode assembly according to claim 1 , wherein each of the electrode tabs is arranged to at least partially overlap an adjacent electrode tab in the stacking direction.

9. 2. The electrode assembly of claim 1, wherein some of the electrode tabs at least partially overlap adjacent electrode tabs in the stacking direction, and the remainder of the electrode tabs are arranged so as not to overlap any electrode tabs in the stacking direction.

10. The electrode assembly according to any one of claims 7 to 9, wherein an area of ​​one or more metal connectors selected from the first metal connector and the second metal connector that is electrically connected to each of the electrode tabs is 50% or more of the total area of ​​each of the electrode tabs.

11. An electrode assembly as described in claim 1, wherein multiple electrode tabs of the same polarity are all completely covered at the top and bottom by the first metal connector and the second metal connector.

12. The electrode assembly of claim 1 , wherein the polymer substrate has a thickness of 3 μm to 20 μm, and the metal layers each have a thickness of 0.2 μm to 3 μm.

13. 2. The electrode assembly according to claim 1, wherein the polymer substrate constituting the electrode tab is made of at least one material selected from the group consisting of polyolefin (PO), polyethylene terephthalate (PET), and cellulose.

14. The electrode assembly according to claim 1 , wherein the metal layer constituting the electrode tab is made of one or more materials selected from the group consisting of Ni, Cu, Al, and stainless steel.

15. 2. The electrode assembly of claim 1, wherein the first metal connector and the second metal connector are each made of one or more materials selected from Ni, Cu, Al, and stainless steel.

16. The electrode assembly of claim 1 , wherein the first metal connector, the second metal connector, and the metal layer of the electrode tab are made of the same material.

17. The electrode assembly of claim 1 , wherein at least one selected from the first metal connector and the second metal connector is connected to an electrode lead.

18. A secondary battery comprising the electrode assembly according to claim 1.

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