Battery cell assembly

Abstract

The utility model discloses a battery cell assembly. The battery cell assembly comprises a pole piece and a pole lug, the pole piece comprises a current collector and a first coating, the current collector is provided with a first surface and a second surface which are opposite to each other, and the first coating is connected to the first surface; the tab is arranged on one side where the second surface is located, the tab is provided with a connecting part, and the connecting part is connected with the second surface; wherein the first plating layer and the connecting part are correspondingly arranged along the thickness direction of the current collector. According to the battery core assembly disclosed by the utility model, the first plating layer corresponding to the connecting part is arranged in the thickness direction of the current collector, so that the structural thickness of the position, corresponding to the connecting part, of the pole piece is increased, and the tensile capacity of the tab on the pole piece can be improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field especially is related to a battery cell subassembly. BACKGROUND

[0002] Generally, the battery cell subassembly includes a pole piece and a tab, the pole piece includes a current collector and an active material layer arranged on the current collector, and the tab is arranged on the current collector.

[0003] With the increasing demand for energy density of lithium batteries, the structure design of the current collector is becoming thinner and thinner, the effective area of the active material layer coated on the current collector is becoming larger and larger, and the area reserved on the current collector for the tab welding is becoming smaller and smaller, which leads to poor tensile resistance of the tab on the pole piece after the tab is welded on the current collector. SUMMARY

[0004] The utility model aims at at least one of the technical problems existing in the prior art. To this end, the utility model provides a battery cell subassembly which can improve the tensile resistance of the tab on the pole piece.

[0005] The utility model embodiment provides a battery cell subassembly, which comprises:

[0006] The pole piece includes a current collector and a first plating layer, the current collector has a first surface and a second surface opposite to each other, and the first plating layer is connected to the first surface;

[0007] The tab is arranged on one side of the second surface, and the tab is provided with a connecting part connected to the second surface; wherein

[0008] The first plating layer and the connecting part are correspondingly arranged in the thickness direction of the current collector.

[0009] The heat dissipation structure according to the utility model embodiment has at least the following beneficial effects:

[0010] By arranging the first plating layer corresponding to the connecting part in the thickness direction of the current collector, the structural thickness of the position corresponding to the pole piece and the connecting part is increased, so that the position corresponding to the pole piece and the connecting part has sufficient structural thickness to connect and fix the tab. When the tab is subjected to external tensile force, the first plating layer and the current collector can jointly resist the external tensile force on the tab, and the first plating layer can support the current collector and the tab on the first surface. In this way, the structural strength and the connection strength of the position corresponding to the pole piece and the connecting part are improved, and the tensile resistance of the tab on the pole piece and the structural stability are improved. The polarization of the battery cell subassembly caused by the small area of the connecting part can be avoided, and the electrical performance consistency of the battery cell subassembly is good.

[0011] According to some embodiments of the present application, the projection of the connecting portion is located within the projection range of the first plating layer on a projection plane perpendicular to the thickness direction of the current collector.

[0012] According to some embodiments of the present application, the current collector comprises a copper foil, and the first plating layer comprises copper metal, nickel metal, silver metal, titanium metal or tin metal.

[0013] According to some embodiments of the present application, the current collector comprises an aluminum foil, and the first plating layer comprises aluminum metal, silver metal or nickel metal.

[0014] According to some embodiments of the present application, the pole piece further comprises a second plating layer, the second plating layer is connected to the second surface, and the connecting portion is connected to one side of the second plating layer away from the current collector.

[0015] According to some embodiments of the present application, the projection of the connecting portion is located within the projection range of the second plating layer on a projection plane perpendicular to the thickness direction of the current collector.

[0016] According to some embodiments of the present application, the current collector comprises a copper foil, the tab comprises nickel metal, and the second plating layer comprises copper metal, nickel metal, silver metal, titanium metal or tin metal.

[0017] According to some embodiments of the present application, the sum of the thicknesses of the first plating layer, the second plating layer and the current collector is greater than or equal to 6um.

[0018] According to some embodiments of the present application, the current collector comprises an aluminum foil, the tab comprises aluminum metal, and the second plating layer comprises aluminum metal, silver metal or nickel metal.

[0019] According to some embodiments of the present application, the sum of the thicknesses of the first plating layer, the second plating layer and the current collector is greater than or equal to 8um.

[0020] Additional aspects and advantages of the present application will be given in part in the following description, become apparent from the following description, or be understood by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0022] Figure 1 A top view of the battery cell assembly provided by one embodiment of the present application is shown;

[0023] Figure 2 A Figure 1 A sectional view of the battery cell assembly shown in the direction of A-A is shown.

[0024] REFERENCE NUMERALS:

[0025] Battery cell assembly 100;

[0026] Pole piece 10; current collector 11; first surface 101; second surface 102; first plating layer 12; second plating layer 13; first active material layer 14; second active material layer 15; second groove 103;

[0027] Tab 20; connecting portion 21. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are merely intended to explain the present application, and cannot be understood as limiting the present application.

[0029] In the description of the present application, it should be understood that, in relation to the orientation description, for example, the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the present application, which indicates or implies that the device or element indicated must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0030] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0031] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0032] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0033] In the related art, the thickness of the current collector is thin, and the area reserved on the current collector for the tab welding is small, and accordingly, the structural strength of the connection part of the current collector and the tab is also weak, which leads to poor tensile resistance of the tab on the pole piece, and thus, the structural stability of the tab on the pole piece is also poor in the process, which further leads to increased polarization of the battery cell and poor electrical performance consistency.

[0034] Therefore, the utility model embodiment provides a battery cell assembly 100 which can improve the tensile resistance of the tab 20 on the pole piece 10.

[0035] It can be understood that the battery cell assembly 100 can be a winding type battery cell structure or a stacked type battery cell structure.

[0036] Please refer to Figure 1 and Figure 2 , the battery cell assembly 100 includes a pole piece 10 and a tab 20. The pole piece 10 includes a current collector 11 and a first plating layer 12, the current collector 11 has a first surface 101 and a second surface 102 opposite to each other, and the first plating layer 12 is connected to the first surface 101; the tab 20 is arranged on the side where the second surface 102 is located, and the tab 20 is provided with a connecting part 21 connected to the second surface 102; wherein the first plating layer 12 and the connecting part 21 are correspondingly arranged along the thickness direction Z of the current collector 11.

[0037] In the utility model embodiment, by arranging the first plating layer 12 corresponding to the connecting part 21 in the thickness direction Z of the current collector 11, the structural thickness of the position corresponding to the connecting part 21 of the pole piece 10 is increased, so that the position corresponding to the connecting part 21 of the pole piece 10 has sufficient structural thickness to connect and fix the tab 20, when the tab 20 is subjected to external tensile force, the first plating layer 12 and the current collector 11 can jointly resist the external tensile force on the tab 20, and the first plating layer 12 can support the current collector 11 and the tab 20 on the first surface 101, in this way, the structural strength and the connection strength of the position corresponding to the connecting part 21 of the pole piece 10 are improved, and thus the tensile resistance and the structural stability of the tab 20 on the pole piece 10 are improved, which can avoid the situation that the polarization of the battery cell assembly 100 is increased due to the small area of the connecting part 21, and ensure that the electrical performance consistency of the battery cell assembly 100 is good.

[0038] In addition, the first plating layer 12 is located on the first surface 101, and the connecting part 21 is located on the second surface 102, that is, the first plating layer 12 is located on the side of the current collector 11 opposite to the connecting part 21, and with the second surface 102 as the reference, the height of the tab 20 after being connected to the second surface 102 can be avoided from being raised due to the arrangement of the first plating layer 12, so that the connection between the current collector 11 and the tab 20 can be relatively flat, the connection and fixation of the tab 20 on the current collector 11 are facilitated, and the structural thickness on the side where the second surface 102 is located is avoided from being large.

[0039] In the implementation, the connecting portion 21 is located on the side of the tab 20 facing the current collector 11, and the connecting portion 21 is connected and fixed to the current collector 11 by welding to achieve the connection and fixation of the current collector 11 and the tab 20 to each other, wherein the welding range between the current collector 11 and the tab 20 is the range of the connecting portion 21.

[0040] In the implementation, the first plating layer 12 can be connected to the first surface 101 of the current collector 11 by chemical deposition, electroplating, evaporation, magnetron sputtering, or the like.

[0041] In some embodiments, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the connecting portion 21 is located within the projection of the first plating layer 12, that is, along the thickness direction Z of the current collector 11, the area formed by the first plating layer 12 covers the area formed by the connecting portion 21, and the position where the current collector 11 and the tab 20 are connected is located within the position where the first plating layer 12 and the current collector 11 are connected. In this way, the first plating layer 12 can better support the current collector 11 and the tab 20, and ensure the structural strength and connection strength of the corresponding position of the tab 10 and the connecting portion 21.

[0042] In some embodiments, the current collector 11 includes a copper foil, that is, the current collector 11 is a negative current collector; and the first plating layer 12 includes copper metal, nickel metal, silver metal, titanium metal, or tin metal.

[0043] In some embodiments, the first plating layer 12 includes copper metal, so that the good electrochemical compatibility between the current collector 11 made of copper foil and the first plating layer 12 made of copper metal can avoid unnecessary side reactions inside the battery, and copper has excellent electrical conductivity, which can improve the current-carrying capacity between the tab 10 and the tab 20, reduce the risk of mechanical damage caused by thermal stress, and be conducive to the stability and reliability of the connection between the current collector 11 and the first plating layer 12.

[0044] In some embodiments, the current collector 11 includes an aluminum foil, that is, the current collector 11 is a positive current collector; and the first plating layer 12 includes aluminum metal, silver metal, and nickel metal.

[0045] In some embodiments, the first plating layer 12 includes aluminum metal, so that the good electrochemical compatibility between the current collector 11 made of aluminum foil and the first plating layer 12 made of aluminum metal can avoid unnecessary side reactions inside the battery, and aluminum has relatively excellent electrical conductivity, which can improve the current-carrying capacity between the tab 10 and the tab 20, reduce the risk of mechanical damage caused by thermal stress, and be conducive to the stability and reliability of the connection between the current collector 11 and the first plating layer 12.

[0046] In some embodiments, the pole piece 10 further comprises a second plating layer 13 connected to the second surface 102, and the connecting portion 21 is located on a side of the second plating layer 13 away from the current collector 11, that is, the first plating layer 12, the second plating layer 13 and the connecting portion 21 are correspondingly arranged along the thickness direction Z of the current collector 11. By arranging the second plating layer 13 corresponding to the connecting portion 21 on the second surface 102, the second plating layer 13 is located between the current collector 11 and the tab 20, and the tab 20 is connected to the current collector 11 through the second plating layer 13, further increasing the structural thickness of the position of the pole piece 10 corresponding to the connecting portion 21. When the tab 20 is subjected to an external pulling force, the first plating layer 12 and the second plating layer 13 resist the external pulling force on the tab 20 together on the opposite surfaces of the current collector 11, and the second plating layer 13 can support the tab 20 on the second surface 102. In this way, the structural strength and the connection strength of the position of the pole piece 10 corresponding to the connecting portion 21 are further improved, and the tensile capacity and the structural stability of the tab 20 on the pole piece 10 are further improved.

[0047] It is worth noting that, with the second surface 102 as the reference, although arranging the second plating layer 13 on the second surface 102 increases the structural thickness on the side where the second surface 102 is located and raises the height of the tab 20 on the side where the second surface 102 is located, the second plating layer 13 can balance the structural thicknesses of the opposite sides of the current collector 11, avoiding the need to set the thickness of the first plating layer 12 on the side where the first surface 101 is located to be relatively large (to ensure the structural strength and the connection strength of the position of the pole piece 10 corresponding to the connecting portion 21). That is to say, when the second surface 102 is provided with the second plating layer 13, the thickness of the first plating layer 12 can be set to be relatively small, and at the same time, due to the presence of the first plating layer 12, the thickness of the second plating layer 13 can also be set to be relatively small. The structural thickness formed by the first plating layer 12, the second plating layer 13 and the current collector 11 can ensure the structural strength and the connection strength of the position of the pole piece 10 corresponding to the connecting portion 21.

[0048] In the specific implementation process, the second plating layer 13 can be connected to the second surface 102 of the current collector 11 by chemical deposition, electroplating, evaporation, magnetron sputtering and other process methods.

[0049] In some embodiments, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the connecting portion 21 is located within the projection of the second plating layer 13, that is, along the thickness direction Z of the current collector 11, the area formed by the second plating layer 13 covers the area formed by the connecting portion 21, and the position where the second plating layer 13 and the tab 20 are connected is within the position where the second plating layer 13 and the current collector 11 are connected. In this way, the second plating layer 13 can better support the tab 20 and ensure the structural strength and connection strength of the position corresponding to the tab 20 and the connecting portion 21.

[0050] In some embodiments, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the first plating layer 12 and the projection of the second plating layer 13 completely coincide, that is, along the thickness direction Z of the current collector 11, the area formed by the first plating layer 12 and the area formed by the second plating layer 13 are the same in size and coincide in position, and the position where the first plating layer 12 and the current collector 11 are connected coincides with the position where the second plating layer 13 and the current collector 11 are connected; or, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the second plating layer 13 is located within the projection of the second plating layer 13, that is, along the thickness direction Z of the current collector 11, the area formed by the first plating layer 12 covers the area formed by the second plating layer 13, and the position where the second plating layer 13 and the current collector 11 are connected is within the position where the first plating layer 12 and the current collector 11 are connected.

[0051] In some embodiments, the current collector 11 comprises a copper foil, that is, the current collector 11 is a negative current collector; the tab 20 comprises nickel metal; and the second plating layer 13 comprises copper metal, nickel metal, silver metal, titanium metal or tin metal.

[0052] In some embodiments, the second plating layer 13 comprises nickel metal. On the one hand, the good electrochemical compatibility between the tab 20 made of nickel metal and the second plating layer 13 made of nickel metal can avoid unnecessary side reactions inside the battery, and nickel has good electrical conductivity, which can improve the current-carrying capacity between the current collector 10 and the tab 20 and reduce the risk of mechanical damage caused by thermal stress. On the other hand, the nickel metal in the second plating layer 13 can fill the fine pores and protrusions on the surface of the copper foil of the current collector 11, and the nickel metal of the second plating layer 13 also enhances the wear resistance and scratch resistance of the copper foil, making the copper foil more stable and reliable when subjected to external forces and less likely to be welded. After the tab 20 is welded to the current collector 11 through the second plating layer 13, the bonding force between the metal molecules of the current collector 11 and the tab 20 can be improved, thereby improving the tensile strength of the tab 20 on the tab 10 after welding. Of course, the second plating layer 13 can also comprise other metals, such as copper metal, silver metal, titanium metal and / or tin metal.

[0053] The tab 20 can be a copper-nickel-plated tab 20 or a nickel tab 20.

[0054] In some embodiments, the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is greater than or equal to 6 um. Through the above parameter design, the tensile strength of the tab 20 on the tab sheet 10 can be significantly improved to meet the tensile strength requirement of the tab 20 on the tab sheet 10. The thickness H2 of the current collector 11 is less than or equal to 5 um, and the thicknesses of the first plating layer 12 and the second plating layer 13 can be equal. For example, when the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is equal to 6 um, and the thickness H2 of the current collector 11 is equal to 5 um, the thickness of the first plating layer 12 can be equal to 0.5 um.

[0055] In some embodiments, the current collector 11 comprises an aluminum foil, i.e., the current collector 11 is a positive electrode current collector; the tab 20 comprises aluminum metal; and the second plating layer 13 comprises aluminum metal, silver metal or nickel metal.

[0056] In some embodiments, the second plating layer 13 comprises silver metal. In this way, the second plating layer 13 made of silver metal can improve the bonding force between the current collector 11 made of aluminum foil and the tab 20 made of aluminum metal, thereby improving the tensile strength of the tab 20 on the tab sheet 10 after welding. In addition, silver has good electrical conductivity, which can improve the current carrying capacity between the tab sheet 10 and the tab 20. Of course, the second plating layer 13 can also comprise other metals, such as aluminum metal and / or nickel metal.

[0057] The tab 20 can be an aluminum tab 20.

[0058] In some embodiments, the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is greater than or equal to 8 um. Through the above parameter design, the tensile strength of the tab 20 on the tab sheet 10 can be significantly improved to meet the tensile strength requirement of the tab 20 on the tab sheet 10. The thickness H2 of the current collector 11 is less than or equal to 5 um, and the thicknesses of the first plating layer 12 and the second plating layer 13 can be equal. For example, when the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is equal to 8 um, and the thickness H2 of the current collector 11 is equal to 5 um, the thickness of the first plating layer 12 can be equal to 1.5 um.

[0059] In some embodiments, the pole piece 10 further comprises a first active material layer 14 and a second active material layer 15. The first active material layer 14 is arranged on the first surface 101, and the second active material layer 15 is arranged on the second surface 102. The first active material layer 14 defines a first groove on the first surface 101, and the second active material layer 15 defines a second groove 103 on the second surface 102. The first groove and the second groove 103 are arranged correspondingly along the thickness direction Z of the current collector 11. The first plating layer 12 is located in the first groove, and the second plating layer 13 is located in the second groove 103. That is, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the first plating layer 12 is located within the projection of the first groove, and the projection of the second plating layer 13 is located within the projection of the second groove 103.

[0060] In some embodiments, in the projection plane perpendicular to the thickness direction Z of the current collector 11, the projection of the first groove and the projection of the second groove 103 completely coincide. That is, along the thickness direction Z of the current collector 11, the area formed by the first groove and the area formed by the second groove 103 are the same in size and coincide in position.

[0061] In the specific implementation process, the tab 20 can be welded on the second plating layer 13 by using a three-point welding process or a row welding process. The welding method can use ultrasonic welding. Ultrasonic welding is to use high-frequency vibration waves to transmit energy to the surfaces of two objects to be welded. Under pressure, the two metal objects are heated by friction, so that the molecules penetrate and fuse with each other. After ultrasonic welding, the foil can be divided into three states: first, the metal in the welding point part is heated, and the double metal molecules penetrate and fuse with each other; second, the annealed metal in the welding point edge is heated but not fused; and third, the normal metal is not heated. The result obtained in the tensile test is the tensile force represented by the metal in the state with the lowest strength among the three states, so as to represent the tensile strength between the pole piece 10 and the tab 20.

[0062] The tab 20 of the above-mentioned battery cell assembly 100 is subjected to a tensile test, and the test results in Table 1 below are obtained.

[0063] Table 1 Embodiments 1-12

[0064]

[0065]

[0066] In the above embodiments, the groove is the first groove and the second groove 103, and the length L2 and the width W1 of the first groove and the second groove 103 are equal.

[0067] As can be seen from Table 1, with the increase of the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11, the average tensile force of the tab 20 of the three-point welding and the row welding is increased accordingly. In order to ensure the process efficiency, when the current collector 11 is a copper foil, the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is greater than or equal to 6um, then the welding tensile force of the tab 20 using the three-point welding process can reach 15.47N, and the welding tensile force of the negative tab 20 using the row welding process can reach 12.67N, so that the tensile capacity requirement of the negative tab 20 on the negative electrode plate 10 can be met; when the current collector 11 is an aluminum foil, the sum H1 of the thicknesses of the first plating layer 12, the second plating layer 13 and the current collector 11 is greater than or equal to 8um, then the welding tensile force of the positive tab 20 using the three-point welding process can reach 15.05N, and the welding tensile force of the positive tab 20 using the row welding process can reach 13.89N, so that the tensile capacity requirement of the positive tab 20 on the positive electrode plate 10 can be met.

[0068] In some embodiments, the number of the electrode plates 10 is at least two, wherein at least one is the negative electrode plate 10, and at least one is the positive electrode plate 10. The current collector 11 of the positive electrode plate 10 comprises a copper foil, the first plating layer 12 of the positive electrode plate 10 comprises copper metal, the second plating layer 13 of the positive electrode plate 10 comprises nickel metal, and the positive tab 20 connected to the positive electrode plate 10 comprises nickel metal; the current collector 11 of the negative electrode plate 10 comprises an aluminum foil, the first plating layer 12 of the negative electrode plate 10 comprises aluminum metal, the second plating layer 13 of the negative electrode plate 10 comprises silver metal, and the negative tab 20 connected to the negative electrode plate 10 comprises aluminum metal.

[0069] The embodiments of the utility model are described in detail above in combination with the drawings, but the utility model is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge range possessed by ordinary skilled in the art without departing from the purpose of the utility model. In addition, the embodiments of the utility model and the features in the embodiments can be combined with each other without conflict.

Claims

1. An electrochemical cell assembly, comprising: The application relates to a polar piece, comprising: a polar piece comprising a current collector and a first plating layer, the current collector having a first surface and a second surface opposite to each other, and the first plating layer being connected to the first surface; a tab provided on a side where the second surface is located, the tab being provided with a connecting part connected to the second surface; wherein the first plating layer and the connecting part are correspondingly arranged along the thickness direction of the current collector.

2. The cell assembly of claim 1, wherein, In a projection plane perpendicular to the thickness direction of the current collector, the projection of the connecting part is located within the projection range of the first plating layer.

3. The cell assembly of claim 1, wherein, The current collector comprises a copper foil, and the first plating layer comprises copper metal, nickel metal, silver metal, titanium metal or tin metal.

4. The cell assembly of claim 1, wherein, The current collector comprises an aluminum foil, and the first plating layer comprises aluminum metal, silver metal or nickel metal.

5. The cell assembly of claim 1, wherein, The polar piece further comprises a second plating layer connected to the second surface, and the connecting part is connected to a side of the second plating layer away from the current collector.

6. The cell assembly of claim 5, wherein, In a projection plane perpendicular to the thickness direction of the current collector, the projection of the connecting part is located within the projection range of the second plating layer.

7. The cell assembly of claim 5, wherein, The current collector comprises a copper foil, the tab comprises nickel metal, and the second plating layer comprises copper metal, nickel metal, silver metal, titanium metal or tin metal.

8. The cell assembly of claim 7, wherein, The sum of the thicknesses of the first plating layer, the second plating layer and the current collector is greater than or equal to 6 um.

9. The cell assembly of claim 5, wherein, The current collector comprises an aluminum foil, the tab comprises aluminum metal, and the second plating layer comprises aluminum metal, silver metal or nickel metal.

10. The cell assembly of claim 9, wherein, The sum of the thicknesses of the first plating layer, the second plating layer and the current collector is greater than or equal to 8 um.

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