Pole piece assembly and battery cell

Abstract

The utility model discloses a pole piece assembly and a battery cell. The pole piece assembly comprises: a current collector having a welding region; the electrode lug is welded to the welding area; the first adhesive layer covers the tab and is electrically connected with the tab; and the second adhesive layer covers the first adhesive layer. According to the pole piece assembly disclosed by the utility model, the conductivity of the tabs can be improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to electrode assemblies and battery cells. Background Technology

[0002] With the increasing global demand for clean energy, high-performance power batteries are being used more and more widely in electric vehicles, energy storage systems, and other portable electronic devices. To meet the high demands of these applications for battery performance and range, cell energy density has become a key development indicator. In recent years, battery energy density has been significantly improved through optimized material selection, improved manufacturing processes, and design innovation. However, as cell energy density continues to increase, the thickness of the current collector foil is further reduced. This reduction in current collector foil thickness further weakens the connection strength and conductivity of the electrode tabs.

[0003] To overcome the problem of insufficient connection strength of the electrode tabs, the methods used in related technologies typically involve improving welding power, welding pressure, and welding time. However, improving the connection strength of the electrode tabs in these ways can lead to a decrease in the conductivity of the thinner foil. Therefore, a new electrode sheet with a novel connection structure between the electrode tab and the current collector is needed to improve the conductivity of the electrode tabs. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an electrode assembly that can improve the conductivity of the electrode tab.

[0005] This utility model also proposes a battery cell.

[0006] The electrode assembly according to an embodiment of the first aspect of the present invention includes:

[0007] A current collector having a welding zone;

[0008] A tab, wherein the tab is welded to the welding area;

[0009] A first adhesive layer covers the electrode tab and is electrically connected to the electrode tab;

[0010] A second adhesive layer covers the first adhesive layer.

[0011] The electrode assembly according to the first aspect of the present invention has at least the following beneficial effects: it can improve the conductivity of the electrode tab.

[0012] In this application, the tab is welded to the welding area of ​​the current collector. A first adhesive layer is provided on the side of the tab away from the welding area, covering the outer surface of the tab. Because the first adhesive layer is conductive, it can electrically connect with the tab and the welding area. A second adhesive layer covers the outer surface of the first adhesive layer to protect the tab. Compared with related technologies that use only one layer of non-conductive protective adhesive to cover the tab, this application uses two adhesive layers. The first adhesive layer is electrically connected to the tab, increasing the conductivity of the thinner tab and dispersing the current at the welding point between the tab and the current collector. The second adhesive layer covers the first adhesive layer, protecting both the first adhesive layer and the tab. Therefore, the structural arrangement of this application, which adds a conductive first adhesive layer at the welding point between the tab and the current collector, improves the conductivity of the tab.

[0013] According to some embodiments of the present invention, it also includes tab adhesive, wherein the tab includes a main body and an extension, the main body is welded to the welding area, the extension protrudes from the current collector, and the tab adhesive is disposed on the extension.

[0014] According to some embodiments of the present invention, an active material layer is also included, the current collector has a coating area outside the welding area, the active material layer is disposed in the coating area, and the second adhesive layer partially covers the welding area.

[0015] According to some embodiments of the present invention, an active material layer is also included, the current collector has a coating area outside the welding area, the active material layer is disposed in the coating area, and the second adhesive layer completely covers the welding area.

[0016] According to some embodiments of the present invention, along the thickness direction of the tab, the top surface of the second adhesive layer does not protrude beyond the top surface of the active material layer.

[0017] According to some embodiments of the present invention, the second adhesive layer covers the first adhesive layer and connects the tab adhesive.

[0018] According to some embodiments of the present invention, the first adhesive layer covers the entire welding area.

[0019] According to some embodiments of the present invention, the first adhesive layer is adhesive paper.

[0020] According to some embodiments of the present invention, along the thickness direction of the tab, the projection of the second adhesive layer completely covers the projection of the first adhesive layer.

[0021] The battery cell according to an embodiment of the second aspect of the present invention includes the electrode assembly described in any one of the above descriptions.

[0022] The battery cell according to the second aspect of the present invention has at least the following beneficial effects: it can improve the conductivity of the tabs.

[0023] In this application, the tab is welded to the welding area of ​​the current collector. A first adhesive layer is provided on the side of the tab away from the welding area, covering the outer surface of the tab. Because the first adhesive layer is conductive, it can electrically connect with the tab and the welding area. A second adhesive layer covers the outer surface of the first adhesive layer to protect the tab. Compared with related technologies that use only one layer of non-conductive protective adhesive to cover the tab, this application uses two adhesive layers. The first adhesive layer is electrically connected to the tab, increasing the conductivity of the thinner tab and dispersing the current at the welding point between the tab and the current collector. The second adhesive layer covers the first adhesive layer, protecting both the first adhesive layer and the tab. Therefore, the structural arrangement of this application, which adds a conductive first adhesive layer at the welding point between the tab and the current collector, improves the conductivity of the tab.

[0024] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0026] Figure 1 This is a schematic diagram of the first embodiment of the electrode assembly of this utility model;

[0027] Figure 2 This is a cross-sectional view of the first embodiment of the electrode assembly of this utility model;

[0028] Figure 3 This is a schematic diagram of a second embodiment of the electrode assembly of this utility model;

[0029] Figure 4 This is a cross-sectional view of a second embodiment of the electrode assembly of this utility model;

[0030] Figure 5 This is a schematic diagram of the third embodiment of the electrode assembly of this utility model;

[0031] Figure 6 This is a cross-sectional view of the third embodiment of the electrode assembly of this utility model.

[0032] Figure label:

[0033] Current collector 100; welding area 101; coating area 102; tab 200; main body 210; extension 220; first adhesive layer 300; second adhesive layer 400; tab adhesive 500; active material layer 600. Detailed Implementation

[0034] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0035] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0036] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0038] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] With the continued growth of global demand for clean energy, high-performance power batteries are being used more and more widely in electric vehicles, energy storage systems, and portable electronic devices. To meet the high demands of these fields for battery performance and range, improving the energy density of battery cells has become a key technical indicator. In recent years, significant progress has been made in battery energy density through optimized material selection, improved manufacturing processes, and design innovation. However, as cell energy density continues to increase, the thickness of the current collector foil is also decreasing, leading to a decline in the strength of the tab connection and conductivity.

[0040] Current collectors are a crucial component in batteries used to collect current, and are typically made of highly conductive metals such as aluminum or copper. To improve the energy density of battery cells, the industry commonly employs methods to thin the current collector foil, as thinner foils reduce the proportion of inactive materials, thus freeing up space for more active materials. However, with the continuous reduction in foil thickness, a series of new problems have arisen, the most prominent being insufficient tab connection strength.

[0041] As the current collector foil becomes thinner, the connection strength of the tabs becomes insufficient, and their conductivity is also affected. To address this insufficient connection strength, existing technologies typically employ methods such as adjusting welding parameters, including increasing welding power, welding pressure, or extending welding time. While these measures can enhance the connection strength of the tabs to some extent, they also impose additional thermal stress on the thinner foil, thereby weakening its conductivity and potentially damaging the foil itself. Although adjusting welding parameters (such as power, pressure, and time) can partially improve this situation in related technologies, this does not fundamentally solve the problem and instead increases the complexity and cost of the manufacturing process.

[0042] The tab is a crucial structure connecting the current collector to the external circuitry, used to conduct current from inside the battery cell to the external load. Traditionally, the tab is fixed to the current collector by welding or other physical connections. When the foil thickness is large, this connection method provides sufficient mechanical strength and electrical performance. However, as the foil thickness decreases, the contact area at the tab connection decreases accordingly, leading to a significant drop in connection strength. This not only affects the long-term stability and reliability of the battery but also poses safety risks in certain situations, such as increased resistance, overheating, or even short circuits caused by loose connections.

[0043] Therefore, there is an urgent need to develop an electrode assembly with a novel tab-current collector connection structure to improve the conductivity of the tabs. This requires not only ensuring sufficient mechanical strength even with very thin foil, but also guaranteeing good electrical contact to avoid heat generation and efficiency loss due to increased resistance. Simultaneously, it is necessary to simplify the manufacturing process to ensure feasibility and economic efficiency in large-scale production.

[0044] Reference Figures 1 to 6 According to an embodiment of the first aspect of the present invention, an electrode assembly includes a current collector 100, a tab 200, a first adhesive layer 300, and a second adhesive layer 400. The current collector 100 has a welding area 101, the tab 200 is welded to the welding area 101, the first adhesive layer 300 covers the tab 200 and is electrically connected to the tab 200, and the second adhesive layer 400 covers the first adhesive layer 300.

[0045] The electrode assembly according to the first aspect of the present invention has at least the following beneficial effects: it can improve the conductivity of the tab 200.

[0046] In this application, the tab 200 is welded to the welding area 101 of the current collector 100. A first adhesive layer 300 is provided on the side of the tab 200 away from the welding area 101. This first adhesive layer 300 covers the outer surface of the tab 200. Because the first adhesive layer 300 is conductive, it can be electrically connected to the tab 200 and the welding area 101. A second adhesive layer 400 covers the outer surface of the first adhesive layer 300 to protect the tab 200. Compared with the related technology design that only uses a single layer of non-conductive protective adhesive to cover the tab 200, this application provides two adhesive layers. The first adhesive layer 300 is electrically connected to the tab 200, increasing the conductivity of the thinner tab 200 and dispersing the current at the welding point between the tab 200 and the current collector 100. The second adhesive layer 400 covers the first adhesive layer 300, protecting both the first adhesive layer 300 and the tab 200. Therefore, the structural arrangement of adding a conductive first adhesive layer 300 at the welding point between the tab 200 and the current collector 100 in this application can improve the conductivity of the tab 200.

[0047] By incorporating the first adhesive layer 300 of this application, which is conductive and adhered to the surface of the tab 200, the conductivity of the tab 200 is increased, and the connection strength of the tab 200 is further enhanced. This ensures that the connection between the tab 200 and the current collector 100 will not loosen or break under various operating conditions (such as vibration, impact, etc.). This further enhances the mechanical stability of the battery and reduces safety hazards caused by connection failures, such as the risk of internal short circuits, electrolyte leakage, or even explosion.

[0048] Specifically, the first adhesive layer 300 is a conductive adhesive layer, mainly composed of resin and conductive particles. It has a certain degree of adhesion and conductivity to the tab 200, allowing it to adhere to the tab 200 and maintain good electrical connection with it. Simultaneously, the first adhesive layer 300 is electrolyte resistant, remaining stable in the electrolyte without reacting. The second adhesive layer 400 is a tab protective layer, covering the outside of the first adhesive layer 300 to protect both the tab 200 and the first adhesive layer 300. It is primarily made of PVC (polyvinyl chloride), protecting the tab 200 from physical damage and environmental factors, enhancing the overall performance and safety of the battery. Furthermore, PVC itself has good electrical insulation properties, effectively isolating the positive and negative tabs 200 and preventing short circuits caused by poor contact or other reasons.

[0049] According to some embodiments of this utility model, it also includes tab adhesive 500. The tab 200 includes a main body 210 and an extension 220. The main body 210 is welded to the welding area 101, and the extension 220 protrudes from the current collector 100, with the tab adhesive 200 disposed on the extension 220. Generally, the tab adhesive 500 is adhered to the portion of the Cu / Al tab 200 bonded to the top sealing aluminum-plastic film PP layer at the top sealing edge, and the material is mainly PP (polypropylene). The tab adhesive 500 can provide additional mechanical support, ensuring a firm bond between the tab 200 and the top sealing aluminum-plastic film. This enhanced mechanical connection can effectively prevent the tab 200 from loosening or falling off due to external impact or vibration, improving the stability of the entire battery structure. By adhering the tab adhesive 500 between the tab 200 and the top sealing aluminum-plastic film PP layer, an effective sealing barrier can be formed, preventing moisture, air, and other external substances from entering the battery interior. Furthermore, while maintaining good electrical insulation, it ensures a firm fixation between the tab 200 and the top sealing aluminum-plastic film, and at the same time, the tab adhesive 500 and the PP layer of the aluminum-plastic film ensure good insulation between the tab 200 and the aluminum layer of the aluminum-plastic film.

[0050] After all the adhesive tapes, including the first adhesive layer 300, the second adhesive layer 400, and the tab adhesive 500, are applied to the tab 200, the connection strength between the tab 200 and the current collector 100 can be guaranteed. At the same time, due to the conductive first adhesive layer 300, the conductivity of the tab 200 can also be improved.

[0051] Specifically, the electrode 200 can be connected in three ways, which will be described in detail below.

[0052] According to some embodiments of this utility model, it further includes an active material layer 600, a coating area 102 is provided on the current collector 100 outside the welding area 101, the active material layer 600 is disposed in the coating area 102, and the second adhesive layer 400 partially covers the welding area 101. (See reference...) Figure 1 , Figure 2 The first method is the traditional tab 200 form, where the tab 200 is directly welded to the current collector 100, and the second adhesive layer 400 completely covers the first adhesive layer 300. That is, the tab protective adhesive completely covers the conductive adhesive and partially covers the welding area 101, thereby improving the conductivity of the tab 200 and the connection strength between it and the current collector 100.

[0053] According to some embodiments of this utility model, it further includes an active material layer 600, a coating area 102 is provided on the current collector 100 outside the welding area 101, the active material layer 600 is disposed in the coating area 102, and the second adhesive layer 400 completely covers the welding area 101. (See reference...) Figure 3 , Figure 4 The second method involves a centrally located tab 200. An active material layer 600 is coated on the current collector 100, and a groove (welding area 101) is formed within the active material layer 600. The tab 200 is welded to this area, and in the thickness direction of the electrode, the tab 200 is located within the groove of the active material layer 600. A first adhesive layer 300 is adhered to the outer surface of the tab 200, and a second adhesive layer 400 is disposed on the outer surface of the first adhesive layer 300. It should be noted that when the tab 200 is both a positive and negative tab, the second adhesive layer 400 needs to cover not only the first adhesive layer 300 and the welding area 101, but also partially cover the active material layer 600 surrounding the welding area 101. This ensures that the welding area 101 of the tab 200 and the surrounding tab cleaning groove are completely covered. This sealing effect improves the overall safety of the battery and reduces the risk of lithium plating. Furthermore, the tab 200 can be welded to the beginning, end, or middle of the electrode.

[0054] According to some embodiments of this utility model, along the thickness direction of the tab 200, the top surface of the second adhesive layer 400 does not protrude beyond the top surface of the active material layer 600. (Refer to...) Figure 5 , Figure 6 The third method is the form of a small anode groove (embedded in adhesive tape) in the centrally located tab 200. That is, an active material layer 600 is coated on the current collector 100, and a groove (welding area 101) is formed in the active material layer 600. The groove is small, and the tab 200 is welded in this area. Furthermore, in the thickness direction of the electrode sheet, the tab 200, the first adhesive layer 300, and the second adhesive layer 400 are completely contained in the groove. That is, the top surface of the second adhesive layer 400 does not protrude from the top surface of the active material layer 600, and the back of the alignment adhesive tape of the anode tab should completely cover the anode cleaning groove.

[0055] Therefore, the electrode sheet can have a flat surface, which is beneficial for subsequent encapsulation processes, such as heat sealing or welding of aluminum-plastic film. Furthermore, it reduces stress at the tab 200, preventing the protruding tab 200 structure from becoming a stress concentration point, which could lead to localized damage or failure under external impact or vibration. If the second adhesive layer 400 protrudes, it may cause poor contact between the encapsulation material and the cell surface, affecting the sealing effect. At the same time, this structural design maximizes the use of limited space, avoiding additional height occupation, and contributes to the miniaturization and weight reduction of the battery.

[0056] According to some embodiments of this utility model, the second adhesive layer 400 covers the first adhesive layer 300 and connects to the tab adhesive 500. The second adhesive layer 400 serves as a protective adhesive layer for the tab, covering the first adhesive layer 300. Simultaneously, to completely cover the tab 200, the second adhesive layer 400 also needs to extend to the tab adhesive 500 and overlap with it. This enhances the mechanical stability and sealing performance of the battery, improves the conductivity of the tab 200, simplifies the manufacturing process, enhances safety and reliability, and makes the tab 200 structure more compact, thereby improving the connection strength of the tab 200.

[0057] According to some embodiments of the present invention, the first adhesive layer 300 covers the entire welding area 101. In addition to completely covering the tab 200, the first adhesive layer 300 can also completely cover the tab 200 and the entire welding area 101, thereby further enhancing the conductivity of the tab 200 and further improving the connection strength between the tab 200 and the current collector 100.

[0058] According to some embodiments of this utility model, the first adhesive layer 300 is adhesive tape. Specifically, in this application, the first adhesive layer 300, as a conductive adhesive, is made into adhesive tape and pasted onto the current collector 100 for soldering the tab 200 to the soldering area 101, rather than being coated onto the soldering area 101. The size of the adhesive tape should cover the tab 200 and extend to the empty foil area of ​​the current collector 100 (i.e., the area not coated with the active material layer 600), but should not exceed the size of the second adhesive layer 400 (tab protective adhesive).

[0059] Using pre-formed conductive adhesive tape ensures a uniform thickness of conductive adhesive within the welding area 101, preventing uneven welding caused by localized areas being too thick or too thin. This helps improve the mechanical strength of the weld joint and reduces the risk of loosening or breakage. Simultaneously, the tape form facilitates precise alignment, ensuring accurate coverage of the target area with each weld, improving production consistency and efficiency. Furthermore, the conductive tape provides a stable conductive path during welding, ensuring efficient and reliable current transmission. Compared to coating methods, the tape form allows for better control over the amount and distribution of conductive adhesive, reducing resistance loss and heat generation.

[0060] According to some embodiments of this utility model, along the thickness direction of the tab 200, the projection of the second adhesive layer 400 completely covers the projection of the first adhesive layer 300. Setting the projection of the second adhesive layer 400 to completely cover the projection of the first adhesive layer 300 ensures complete protection of both the first adhesive layer 300 and the tab 200 by the second adhesive layer 400, preventing the first adhesive layer 300 from being exposed to the second adhesive layer 400, thus avoiding risks such as short circuits caused by the first adhesive layer 300 losing its protection. (Refer to...) Figure 1 The first adhesive layer 300 is completely covered by the second adhesive layer 400. That is, when viewed along the thickness direction of the tab 200, each side of the first adhesive layer 300 is included in the internal region of each side of the second adhesive layer 400.

[0061] The battery cell according to an embodiment of the second aspect of the present invention includes the electrode assembly of any one of the above.

[0062] The battery cell according to the second aspect of the present invention has at least the following beneficial effects: it can improve the conductivity of the tab 200.

[0063] In this application, the tab 200 is welded to the welding area 101 of the current collector 100. A first adhesive layer 300 is provided on the side of the tab 200 away from the welding area 101. This first adhesive layer 300 covers the outer surface of the tab 200. Because the first adhesive layer 300 is conductive, it can be electrically connected to the tab 200 and the welding area 101. A second adhesive layer 400 covers the outer surface of the first adhesive layer 300 to protect the tab 200. Compared with the related technology design that only uses a single layer of non-conductive protective adhesive to cover the tab 200, this application provides two adhesive layers. The first adhesive layer 300 is electrically connected to the tab 200, increasing the conductivity of the thinner tab 200 and dispersing the current at the welding point between the tab 200 and the current collector 100. The second adhesive layer 400 covers the first adhesive layer 300 to protect both the first adhesive layer 300 and the tab 200. Therefore, the structural arrangement of adding a conductive first adhesive layer 300 at the welding point between the tab 200 and the current collector 100 in this application can improve the conductivity of the tab 200. Thus, a battery cell having the electrode assembly of this application can improve the conductivity of the tab 200.

[0064] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrode assembly, characterized in that, include: A current collector having a welding zone; A tab, wherein the tab is welded to the welding area; A first adhesive layer covers the electrode tab and the welding area, and the first adhesive layer is electrically connected to the welding area and the electrode tab; A second adhesive layer covers the first adhesive layer.

2. The electrode assembly according to claim 1, characterized in that, It also includes tab adhesive, wherein the tab includes a main body and an extension, the main body is welded to the welding area, the extension protrudes from the current collector, and the tab adhesive is disposed on the extension.

3. The electrode assembly according to claim 2, characterized in that, It also includes an active material layer, the current collector has a coating area outside the welding area, the active material layer is disposed in the coating area, and the second adhesive layer partially covers the welding area.

4. The electrode assembly according to claim 2, characterized in that, It also includes an active material layer, the current collector has a coating area outside the welding area, the active material layer is disposed in the coating area, and the second adhesive layer completely covers the welding area.

5. The electrode assembly according to claim 3 or 4, characterized in that, Along the thickness direction of the tab, the top surface of the second adhesive layer does not protrude beyond the top surface of the active material layer.

6. The electrode assembly according to claim 2, characterized in that, The second adhesive layer covers the first adhesive layer and connects the tab adhesive.

7. The electrode assembly according to claim 1, characterized in that, The first adhesive layer covers the entire welding area.

8. The electrode assembly according to claim 1, characterized in that, The first adhesive layer is adhesive paper.

9. The electrode assembly according to claim 1, characterized in that, Along the thickness direction of the tab, the projection of the second adhesive layer completely covers the projection of the first adhesive layer.

10. A battery cell, characterized in that, The electrode assembly includes any one of claims 1 to 9.

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