Battery cell, battery module and electric device
By setting a barrier film in the battery cell to prevent lithium ions from depositing on the negative electrode, the lithium deposition phenomenon is solved, and the reliability and performance of the battery are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2026-03-10
AI Technical Summary
Lithium plating is prone to occur on the inner side of the outermost negative electrode plate of a battery cell, corresponding to the area below the positive electrode tab, which leads to lithium waste and reduced battery reliability.
A barrier film is placed in the battery cell, located between the outermost positive and negative electrode plates. The barrier film is used to prevent lithium ions from passing through and to prevent lithium from being deposited on the negative electrode plate.
It effectively alleviates lithium plating, improves the reliability of individual battery cells, avoids the risk of lithium dendrites piercing the separator, and enhances battery performance.
Smart Images
Figure CN223986593U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power battery technology, and more specifically, to a battery cell, a battery module, and an electrical device. Background Technology
[0002] In related technologies, the electrodes in a single battery cell are wound together. Lithium plating is prone to occur on the inner surface of the outermost negative electrode, in the area below the positive electrode tab. This plating not only wastes lithium and reduces battery cycle performance, but the formation of lithium dendrites can also puncture the separator, leading to decreased battery reliability.
[0003] In view of the above, this application is hereby submitted. Utility Model Content
[0004] The purpose of this application is to provide a battery cell, a battery module, and an electrical device that can alleviate lithium plating on the outermost negative electrode and improve the reliability of the battery cell.
[0005] The embodiments of this application can be implemented as follows:
[0006] In a first aspect, this application provides a battery cell, the battery cell including an electrode assembly, the electrode assembly including a positive electrode sheet, a negative electrode sheet, a first separator and a second separator, the second separator, the positive electrode sheet, the first separator and the negative electrode sheet are sequentially stacked and wound to form the electrode assembly;
[0007] The electrode assembly has a flat region, and a barrier film is disposed in the flat region. The barrier film is located between the adjacent positive electrode and the first separator in the outermost ring, and / or the barrier film is located between the adjacent negative electrode and the first separator in the outermost ring. The barrier film is used to prevent lithium ions from passing through.
[0008] The battery cell has intersecting first and second directions. A positive electrode tab is provided at one end of the positive electrode sheet in the first direction. The projection of the barrier film on the outermost positive electrode sheet is connected to or spaced apart from the positive electrode tab on the outermost positive electrode sheet in the first direction.
[0009] In an optional embodiment, the barrier membrane is attached to at least one of the outermost negative electrode, the outermost positive electrode, and the first separator.
[0010] In an optional embodiment, the barrier film is attached to the outermost negative electrode plate, and the projection of the barrier film on the outermost positive electrode plate is connected to the positive electrode tab on the outermost positive electrode plate in a first direction.
[0011] In an optional embodiment, the projection of the barrier film on the outermost positive electrode plate is spaced apart from the positive electrode tab on the outermost positive electrode plate in a first direction, and the spacing is D mm, where D is not greater than 5.
[0012] In an optional embodiment, the barrier membrane has two first sides extending along a first direction and two second sides extending along a second direction. The second side of the barrier membrane near the positive electrode tab is flush with the edge of the outermost positive electrode sheet where the positive electrode tab is disposed. Furthermore, the two ends of the second side of the barrier membrane near the positive electrode tab extend beyond the connection end of the positive electrode tab in the second direction by a dimension W1 mm, where W1 ranges from 1 to 30 mm; and / or,
[0013] The first side of the barrier membrane has a dimension of W2 mm in the first direction, and W2 ranges from 1 to 10.
[0014] In an optional embodiment, the barrier membrane is semi-circular or semi-elliptical, with its straight edge extending along a second direction. The straight edge of the barrier membrane is flush with the edge of the outermost positive electrode plate where the positive electrode tab is located. The two ends of the straight edge of the barrier membrane extend beyond the connection end of the positive electrode tab in the second direction by a dimension W1 mm, where W1 ranges from 1 to 30 mm; and / or,
[0015] The size of the barrier membrane in the first direction is W2 mm, and W2 ranges from 1 to 10.
[0016] In an optional implementation, the thickness of the barrier film is no greater than 50 μm.
[0017] In an optional embodiment, the barrier membrane is bonded to at least one of the negative electrode, the positive electrode, and the first separator using PVDF adhesive.
[0018] In an optional embodiment, the barrier film is at least one of PP film, PE film, PET film, PVC film and nylon film.
[0019] In an optional embodiment, the battery cell further includes a housing and a cover plate. The housing forms a receiving cavity, and the positive electrode, negative electrode, first separator, and second separator are disposed in the receiving cavity. One end of the housing has an opening in a first direction, and the cover plate is used to close the opening.
[0020] Secondly, this application provides a battery module, including the battery cell provided in any of the embodiments of the first aspect above.
[0021] Thirdly, this application provides an electrical device including the battery module provided in the second aspect above.
[0022] The beneficial effects of the battery cell, battery module, and power device provided in this application embodiment include:
[0023] The battery cell provided in this application includes an electrode assembly, which comprises a positive electrode, a negative electrode, a first separator, and a second separator. The second separator, the positive electrode, the first separator, and the negative electrode are sequentially stacked and wound to form the electrode assembly. The electrode assembly also has a flat region, in which a barrier film is disposed. The barrier film is located between adjacent positive and negative electrodes on the outermost ring, and is used to prevent lithium ions from passing through. Positive electrode tabs are disposed at the edges of the outermost positive electrode. The projection of the barrier film on the outermost positive electrode is either connected to or spaced apart from the positive electrode tabs on the outermost positive electrode in the depth direction of the receiving cavity. Due to the compression of the positive electrode tabs, the outermost positive and negative electrodes are deformed, creating a larger gap between them. This lengthens the lithium ion movement path, resulting in insufficient embedding on the outermost negative electrode, and ultimately lithium is deposited on the surface of the negative electrode. In this application, a barrier film is added between the outermost positive and negative electrode plates. The barrier film corresponds to the positive electrode plate below the positive electrode tab. This area is the main area where a large gap is formed between the outermost positive and negative electrode plates due to electrode deformation. The barrier film prevents lithium ions desorbed from the positive electrode plate from moving to the negative electrode plate in this area. Therefore, they cannot reach the corresponding area on the negative electrode plate, and lithium will not be deposited in the corresponding area on the negative electrode plate. This improves the problem of lithium deposition in the area below the positive electrode tab connection terminal on the outermost negative electrode plate, and improves the reliability of the battery cell.
[0024] The battery module provided in this application includes the aforementioned battery cell; the electrical device provided in this application includes the aforementioned battery module, and therefore also has better reliability. Attached Figure Description
[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a schematic diagram of the electrode assembly disposed within the housing in one embodiment of this application;
[0027] Figure 2 This is a schematic diagram of the winding structure of a single battery cell in one embodiment of this application;
[0028] Figure 3 A schematic diagram showing the application of a barrier film attached to the area connected to the positive electrode tab on the outermost positive electrode in one embodiment of this application;
[0029] Figure 4A schematic diagram showing the application of a barrier film on the outermost negative electrode in one embodiment of this application, corresponding to the connection end of the positive electrode tab.
[0030] Figure 5 This is a schematic diagram showing the gap between the edge of the barrier membrane and the connection end of the positive electrode tab on the outermost positive electrode in one embodiment of this application;
[0031] Figure 6 A schematic diagram showing the application of a barrier film to be attached to the area on the outermost positive electrode connected to the connection end of the positive electrode tab in another embodiment of this application;
[0032] Figure 7 This is a schematic diagram showing the application of a barrier film attached to the area on the outermost positive electrode connected to the positive electrode tab in another embodiment of this application.
[0033] Icons: 10-Straight area; 100-Positive electrode sheet; 101-Outermost positive electrode; 110-Positive electrode tab; 20-Bending area; 200-Negative electrode sheet; 201-Outermost negative electrode; 210-Negative electrode tab; 310-First diaphragm; 320-Second diaphragm; 400-Blocking membrane; 410-First side; 420-Second side; 50-Shell; 510-Receiving cavity; 60-Cover plate. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0035] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0037] In the description of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use, they are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application.
[0038] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.
[0039] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.
[0040] As described in the background section, the battery cells of this technology employ a wound electrode assembly. In this assembly, lithium plating is prone to occur on the inner side of the outermost negative electrode, corresponding to the area below the positive electrode tab. This is because the side of the positive electrode with the positive electrode tab aligns with the opening of the casing. When the cover closes the opening, it easily compresses the positive electrode tab, causing deformation on that side of the positive electrode. This deformation affects the negative electrode, causing deformation of the edges of adjacent negative electrode sheets. Since the outermost negative electrode lacks the support of the positive electrode, its edge (corresponding to the area below the positive electrode tab) bends outwards. This prevents the area below the positive electrode tab connection point from adhering tightly to the separator, resulting in separation from the separator. This results in a longer lithium-ion transport path between the region of the positive electrode connected to the positive electrode tab and the corresponding negative electrode. Lithium ions that have been extracted from the region below the positive electrode tab cannot fully embed themselves into the outermost negative electrode when transported to it, thus precipitating on the surface of the negative electrode and forming arc-shaped purple spots. This lithium deposition on the negative electrode not only wastes lithium but also poses a risk of lithium dendrites piercing the separator, leading to reduced reliability of the battery cell.
[0041] To address this issue, this application provides a battery cell that uses a barrier film between the outermost negative and positive electrodes. This barrier film prevents lithium ions released from the region below the positive electrode tab of the outermost positive electrode from being transported to the outermost negative electrode, thereby mitigating the problem of lithium deposition inside the outermost negative electrode and improving the reliability of the battery cell. The battery cell of this application will be described below with reference to embodiments.
[0042] Figure 1 This is a schematic diagram of the electrode assembly disposed within the housing in one embodiment of this application; Figure 2 This is a schematic diagram of the electrode assembly of a battery cell in one embodiment of this application. Figure 1 and Figure 2 As shown, the battery cell provided in this embodiment includes a housing 50, an electrode assembly, and a cover plate 60. The electrode assembly includes a positive electrode 100, a negative electrode 200, a first separator 310, and a second separator 320. The housing 50 forms a receiving cavity 510, and the electrode assembly is disposed within the receiving cavity 510. In this application, the electrode assembly has a wound structure, with the second separator 320, the positive electrode 100, the first separator 310, and the negative electrode 200 sequentially stacked and wound to form the electrode assembly. The electrode assembly has a straight region 10 and a bent region 20, with the positive electrode 100 and the negative electrode 200 stacked in the straight region 10. The flat region 10 is provided with a barrier membrane 400, which is located between the outermost adjacent positive electrode 100 and the first separator 310; and / or, the barrier membrane 400 is located between the outermost adjacent negative electrode 200 and the first separator 310, and the barrier membrane 400 is used to prevent lithium ions from passing through.
[0043] In this embodiment, the electrode assembly is a wound structure. Optionally, during the fabrication of the electrode assembly, the second separator 320, the positive electrode 100, the first separator 310, and the negative electrode 200 are first stacked sequentially, and then wound to obtain the electrode assembly, with the outermost negative electrode 200 located outside the outermost positive electrode 100. Therefore, the separator between the outermost positive electrode 100 and the outermost negative electrode 200 is the first separator 310. During the winding of the electrode, the second separator 320 is located inside the positive electrode 100. After winding, as shown... Figure 2 As shown, the separator adjacent to the inner side of the outermost positive electrode 100 is the second separator 320. Optionally, in the final stage of winding the electrode assembly, the positive electrode 100 and the negative electrode 200 are first cut and winding stops, while the first separator 310 and the second separator 320 can continue to be wound more than one turn, so that the separator is on the outermost side of the electrode assembly, wrapping the positive electrode 100 and the negative electrode 200. In other embodiments, one of the first separator 310 and the second separator 320 may be wound more than one turn than the electrode.
[0044] In this application, the battery cell has intersecting first direction X and second direction Y. A positive electrode tab 110 is provided at one edge of the positive electrode sheet 100 in the flat region 10 in the first direction. The projection of the barrier film 400 onto the outermost positive electrode sheet 100 is either X-connected to or spaced apart from the positive electrode tab 110 on the outermost positive electrode sheet 100 in the first direction. In this embodiment, the housing 50 has an opening at one end in the first direction X, and a cover plate 60 is used to close the opening of the housing 50. The end of the positive electrode sheet 100 with the positive electrode tab 110 is opposite to the cover plate 60 in the depth direction of the receiving cavity 510. In other words, the depth direction of the housing 50 is parallel to the first direction.
[0045] Understandable. Figure 2 The electrode assembly shown is a wound structure, which is formed by winding a second separator 320, a positive electrode 100, a first separator 310, and a negative electrode 200 sequentially stacked together in one direction. Therefore, the number of positive electrode 100 and negative electrode 200 in the wound structure can both be one, and the number of first separator 310 and second separator 320 can also both be one. Along the winding direction, the negative electrode 200 is located on the outer side relative to the positive electrode 100. In the wound electrode assembly, both the positive electrode 100 and the negative electrode 200 have straight sections and bent sections. Multiple straight sections of the positive electrode 100 and multiple straight sections of the negative electrode 200 are stacked in the third direction Z, forming a straight region 10; the bent sections of the positive electrode 100 and the negative electrode 200 form two bent regions 20. Two bending regions 20 are located at opposite ends of the straight region 10 in the second direction Y. In this embodiment, the first direction X, the second direction Y, and the third direction Z are mutually perpendicular, and the first direction X is parallel to the winding axis of the electrode assembly; the winding axis of the electrode assembly is parallel to the depth direction of the receiving cavity 510 of the housing 50. A positive electrode tab 110 is disposed at the edge of one end of the positive electrode sheet 100 in the first direction X, and this edge is opposite to the cover plate 60 in the first direction X. In this embodiment, at least the outermost positive electrode sheet 100 has a positive electrode tab 110 at one end of its first direction X; optionally, each straight segment of the positive electrode sheet 100 has a positive electrode tab 110 at one end of its first direction X. A negative electrode tab 210 is disposed at one end of the negative electrode sheet 200; optionally, each straight segment of the negative electrode sheet 200 has a negative electrode tab 210 at one end of its first direction X. Optionally, the whole formed by the plurality of positive electrode tabs 110 and the whole formed by the plurality of negative electrode tabs 210 are spaced apart in the second direction Y.
[0046] In this embodiment, each straight segment of the positive electrode 100 is rectangular, and each straight segment of the negative electrode 200 is rectangular. The edge of the straight segment of the positive electrode 100 used to set the positive electrode tab 110 is a straight edge and extends along the second direction Y. The edge of the straight segment of the negative electrode 200 used to set the negative electrode tab 210 is also a straight edge and extends along the second direction Y.
[0047] In various embodiments of this application, the barrier membrane 400 is located between the outermost adjacent positive electrode 100 and the outermost negative electrode 200; for example, the barrier membrane 400 is located between the outermost adjacent positive electrode 100 and the first separator 310, or the barrier membrane 400 is located between the outermost adjacent negative electrode 200 and the first separator 310. For ease of description, in this application, the outermost positive electrode 100 in the flat region 10 is defined as the outermost positive electrode 101, and the outermost negative electrode 200 in the flat region 10 is defined as the outermost negative electrode 201; the outermost positive electrode 101 is two straight segments located at both ends in the third direction among the multiple straight segments of the positive electrode 100, and the outermost negative electrode 201 is two straight segments located at both ends in the third direction among the multiple straight segments of the negative electrode 200. Figure 1 , Figure 2 In this embodiment, the electrode assembly has two outermost negative electrodes 201 and two outermost positive electrodes 101, with each of the two outermost negative electrodes 201 corresponding to one outermost positive electrode 101. Optionally, a barrier film 400 may be provided between each of the two outermost negative electrodes 201 and its corresponding outermost positive electrode 101 (i.e., the electrode assembly includes two barrier films 400); or, a barrier film 400 may be provided between one of the outermost negative electrodes 201 and its corresponding outermost positive electrode 101.
[0048] Figure 3 A schematic diagram showing that a barrier film 400 is attached to the area on the outermost positive electrode 101 connected to the connection end of the positive electrode tab 110 in one embodiment of this application; Figure 4 This is a schematic diagram showing the application of a barrier film 400 on the outermost negative electrode 201, corresponding to the connection end of the positive electrode tab 110, in one embodiment of this application. In this application, the barrier film 400 is applied to at least one of the outermost negative electrode 200, the outermost positive electrode 100, and the first separator 310. For example, the barrier film 400 can be applied to the side of the outermost negative electrode 201 facing the outermost positive electrode 101 (e.g.,...). Figure 4 Alternatively, it can be attached to the side of the outermost positive electrode 101 facing the outermost negative electrode 201 (e.g.) Figure 3 Alternatively, it can be attached to the first diaphragm 310 between the outermost negative electrode 201 and the outermost negative electrode 201; or, the barrier membrane 400 can be attached to both the outermost negative electrode 201 and the first diaphragm 310; or, the barrier membrane 400 can be attached to both the outermost positive electrode 101 and the first diaphragm 310.
[0049] In this application, the projection of the barrier film 400 onto the outermost positive electrode 100 is either connected to or spaced apart from the positive electrode tabs 110 on the outermost positive electrode 100 in the first direction X. That is, the projection of the barrier film 400 onto the outermost positive electrode 101 is either connected to or spaced apart from the positive electrode tabs 110 on the outermost positive electrode 101 in the depth direction of the receiving cavity 510 of the housing 50. Specifically, the projection of the barrier film 400 onto the outermost positive electrode 101 is a projection along a third direction. Since the lithium deposited on the outermost negative electrode 201 is usually adjacent to the positive electrode 100 in the depth direction of the receiving cavity 510 of the housing 50, the barrier film 400 can effectively prevent lithium ions from moving to the area on the outermost negative electrode 201 where lithium deposition is likely to occur, even if the edge of the outermost negative electrode 201 is deformed and a large gap is formed between it and the outermost positive electrode 101, thus avoiding lithium deposition on the outermost negative electrode 201.
[0050] Optionally, the projection of the barrier film 400 is connected to the connection end of the positive electrode tab 110 on the outermost positive electrode 101. For example, the barrier film 400 is attached to the outermost negative electrode 200 (i.e., the outermost negative electrode 201), and the projection of the barrier film 400 on the outermost positive electrode 100 (i.e., the outermost positive electrode 101) is connected to the positive electrode tab 110 on the outermost positive electrode 100 in the first direction X. Optionally, one side of the barrier film 400 is flush with the edge on the outermost positive electrode 100 (i.e., the outermost positive electrode 101) where the positive electrode tab 110 is located.
[0051] exist Figure 3 , Figure 4 In this embodiment, one side of the barrier film 400 in the first direction is flush with the edge of the tab provided on the outermost positive electrode 101 or the outermost negative electrode 201. Therefore, when the ends of the outermost positive electrode 101 and the outermost negative electrode 201 with tabs are flush, the projection of the barrier film 400 on the outermost positive electrode 101 can be connected to the connection end of the positive electrode tab 110.
[0052] Figure 5 This is a schematic diagram showing the spacing between the edge of the barrier membrane 400 and the connection end of the positive electrode tab 110 on the outermost positive electrode 101 in one embodiment of this application. Figure 5As shown, optionally, the projection of the barrier film 400 onto the outermost positive electrode 100 (i.e., the outermost positive electrode 101) and the connection end of the positive electrode tab 110 on the outermost positive electrode 100 can also be spaced apart in the first direction X. To ensure good lithium plating prevention, the distance between the projection of the barrier film 400 onto the outermost positive electrode 101 and the corresponding positive electrode tab 110 in the depth direction of the receiving cavity 510 should be controlled within a certain range. For example, the distance between the projection and the connection end of the positive electrode tab 110 in the first direction X is D mm, where D is not greater than 5; optionally, for example, D can be 1-3.
[0053] like Figures 3 to 5 As shown, optionally, the barrier membrane 400 has two first sides 410 extending along a first direction X and two second sides 420 extending along a second direction Y. One second side 420 of the barrier membrane 400 is flush with the edge of the positive electrode tab 110 disposed on the outermost positive electrode sheet 100 (i.e., the outermost positive electrode 101). Specifically, one second side 420 of the barrier membrane 400 is the side of the barrier membrane 400 in the first direction X that is close to the positive electrode tab 110. The two ends of the barrier membrane 400 in the second direction Y respectively extend beyond the connection ends of the positive electrode tab 110 in the second direction Y. Figure 3 In this embodiment, the two ends of the second side 420 of the barrier film 400 near the positive electrode tab 110 in the first direction X extend beyond the connection end of the positive electrode tab 110 by a distance of W1 mm, where W1 ranges from 1 to 30 mm. It can be understood that the area on the outermost negative electrode 201 where lithium plating is likely to occur is related to the width of the positive electrode tab 110 (i.e., the width in the second direction Y). The wider the positive electrode tab 110, the wider the area on the outermost negative electrode 201 where lithium plating is likely to occur. Therefore, the two ends of the second side 420 of the barrier film 400 near the positive electrode tab 110 in the first direction X extend beyond the positive electrode tab 110 to ensure coverage of the area prone to lithium plating, thereby achieving a better anti-lithium plating effect. In this embodiment, the barrier film 400 is quadrilateral.
[0054] Optionally, in one embodiment of this application, the barrier film 400 can be rectangular, with two second sidewalls 420 spaced apart in the first direction X as long sides, extending along the second direction Y; and two first sidewalls 410 spaced apart in the second direction Y as short sides, extending along the first direction X. Optionally, the dimension of the first sidewall 410 of the barrier film 400 in the first direction X is W2 mm; optionally, W2 ranges from 1 to 10. It is understood that if the dimension of the barrier film 400 in the first direction X is too short, the lithium plating prevention effect will be poor, but if it is too long, the total area of the barrier film 400 will be too large, blocking the transport of lithium ions too much, which will have a negative impact on the battery capacity.
[0055] Cyclic performance tests were conducted on battery cells using rectangular barrier films 400 of different sizes (Test Examples 1-6) and battery cells without barrier films 400 (Comparative Example 1), and the results are shown in Table 1.
[0056] Table 1:
[0057]
[0058] As shown in Table 1, compared to Comparative Example 1 which did not use the barrier film 400, the lithium plating phenomenon on the inner side of the outermost negative electrode 200 was suppressed in Test Examples 1-6, which used the barrier film 400. When the distance W1 from the end of the barrier film 400 in the second direction Y to the connection end of the positive electrode tab 110 is small (e.g., W1 is less than 0.5 in Test Example 1), the barrier film 400 can suppress lithium plating. However, due to the small size of the barrier film 400 in the second direction Y, a small amount of lithium plating still occurs. Similarly, when the size W2 of the first side 410 of the barrier film 400 in the first direction X is small (e.g., W2 is less than 0.5 in Test Example 1), the barrier film 400 can suppress lithium plating. However, due to the small size of the barrier film 400 in the first direction X, a small amount of lithium plating still occurs. In Test Example 6, parameters W1, W2, and D were chosen with relatively large values. Although this resulted in better suppression of lithium plating, the excessively large area of the barrier film 400 significantly impacted the capacity of the individual battery cells, making it difficult to achieve the designed energy density. Therefore, in this embodiment, the values of W1 are selected from 1 to 30, W2 from 1 to 10, and D from 5 or less, which balances good suppression of lithium plating with minimal impact on battery capacity.
[0059] In addition to using quadrilateral and rectangular barrier films 400, other shapes of barrier films 400 can also be used. Figure 6 A schematic diagram showing the application of a barrier film 400 to be attached to the area on the outermost positive electrode 101 connected to the connection end of the positive electrode tab 110 in another embodiment of this application. Figure 7 This is a schematic diagram showing the application of a barrier film 400 attached to the area on the outermost positive electrode 101 connected to the positive electrode tab 110 in another embodiment of this application. (See diagram below.) Figure 6 and Figure 7 As shown, optionally, the barrier membrane 400 is semi-elliptical or semi-circular, and the straight edge of the barrier membrane 400 extends along the second direction Y. The straight edge of the barrier membrane 400 is flush with the edge of the positive electrode tab 110 disposed on the outermost positive electrode 101.
[0060] Furthermore, the two ends of the straight edge of the barrier membrane 400 extend beyond the connection end of the positive electrode tab 110 in the second direction Y by a dimension of W1 mm; optionally, W1 ranges from 1 to 30 mm. Figure 6As shown, optionally, the blocking membrane 400 is semi-elliptical, the major axis of the blocking membrane 400 coincides with the straight edge, and the dimension W2 mm of the blocking membrane 400 in its minor axis direction (i.e., the first direction X); optionally, W2 ranges from 1 to 10.
[0061] It should be understood that in alternative embodiments, the shape of the barrier membrane 400 can also be selected as needed, such as trapezoidal, triangular, pentagonal, hexagonal, or even other irregular shapes.
[0062] In various embodiments of this application, optionally, the thickness of the barrier film 400 is no greater than 50 μm. It is understood that excessive thickness can easily affect the thermo-pressing interface of other areas where the barrier film 400 is not attached, thereby affecting the performance of the battery cell. Therefore, the thickness of the barrier film 400 can be controlled within 50 μm.
[0063] Optionally, the barrier membrane 400 is bonded to at least one of the negative electrode 200, the positive electrode 100, and the first separator 310 using PVDF (polyvinylidene difluoride) adhesive. During the fabrication of the battery cell, PVDF particles can be coated onto the barrier membrane 400, or PVDF particles can be coated onto corresponding areas of the negative electrode 200, the positive electrode 100, or the first separator 310, and then the barrier membrane 400 is placed in the corresponding areas. The PVDF particles will be heated and melted during the hot-pressing process, thereby bonding the barrier membrane 400 to the negative electrode 200, the positive electrode 100, or the first separator 310. PVDF adhesive provides excellent bonding, and the barrier membrane 400 is not easily detached even when immersed in electrolyte. Optionally, the thickness of the PVDF adhesive is 3–5 μm; if the PVDF adhesive is too thin, the bonding effect is poor; if the PVDF adhesive is too thick, it will affect the hot-pressing interface of the electrode assembly.
[0064] Optionally, the barrier film 400 is at least one of PP film, PE film, PET film, PVC film and nylon film. The choice of material for the barrier film 400 is not limited to the listed materials. Any material that can completely block or at least partially block lithium ions is acceptable.
[0065] This application also provides a battery module (not shown in the figure), which includes the battery cell provided in the above embodiments of this application. The battery module can be a power battery.
[0066] This application also provides an electrical device, including the battery module provided in this application embodiment. The electrical device can be a new energy vehicle, with the battery module serving as the vehicle's power battery. In other embodiments, the electrical device can also be an aircraft, household appliance, or other electrical equipment.
[0067] In summary, this application provides a battery cell, a battery module, and an electrical device. The battery cell of this application includes an electrode assembly, which comprises a positive electrode 100, a negative electrode 200, a first separator 310, and a second separator 320. The second separator 320, the positive electrode 100, the first separator 310, and the negative electrode 200 are sequentially stacked and wound to form the electrode assembly. The electrode assembly has a flat region 10, on which a barrier film 400 is disposed. The barrier film 400 is located between adjacent positive electrode 100 and negative electrode 200 on the outermost ring, and is used to prevent lithium ions from passing through. Positive electrode tabs 110 are disposed at the edges of the outermost positive electrode 100. The projection of the barrier film 400 onto the outermost positive electrode 100 is either connected to or spaced apart from the positive electrode tabs 110 on the outermost positive electrode 100 in a first direction X. Because the positive electrode tab is easily deformed due to compression, the outermost positive electrode 100 and the outermost negative electrode 200 will have a large gap between them, which will make the lithium ion movement path longer and the lithium ions will not be fully embedded in the outermost negative electrode 200, and lithium will eventually be deposited on the surface of the negative electrode 200. In this application, a barrier film 400 is added between the outermost positive electrode 100 and the negative electrode 200. The barrier film 400 corresponds to the positive electrode 100 below the positive electrode tab 110. This area is the main region where large gaps are formed due to deformation. The barrier film 400 prevents lithium ions desorbed from the positive electrode 100 from moving towards the negative electrode 200, thus preventing them from reaching the corresponding area on the negative electrode 200. Consequently, lithium is not deposited in the corresponding area on the negative electrode 200, thereby improving the problem of lithium deposition in the area below the positive electrode tab 110 connection terminal on the outermost negative electrode 200 and improving the reliability of the battery cell. The battery module provided in this application includes the aforementioned battery cell; the electrical device provided in this application includes the aforementioned battery module, and therefore also has better reliability.
[0068] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.
Claims
1. A battery cell, characterized by, The application relates to a battery cell and a manufacturing method thereof. The electrode assembly comprises a positive electrode tab (100), a negative electrode tab (200), a first separator (310) and a second separator (320), the second separator (320), the positive electrode tab (100), the first separator (310) and the negative electrode tab (200) are sequentially stacked and wound to form the electrode assembly. The battery cell has a first direction (X) and a second direction (Y) intersecting each other, an edge of one end of the positive electrode tab (100) in the first direction (X) of the flat area (10) is provided with a positive electrode lug (110), and a projection of the barrier film (400) on the outermost positive electrode tab (100) is connected or spaced apart from the positive electrode lug (110) on the outermost positive electrode tab (100) in the first direction (X). The barrier film (400) is attached to at least one of the outermost negative electrode tab (200), the outermost positive electrode tab (100) and the first separator (310).
2. The battery cell of claim 1, wherein, The barrier film (400) is attached to the outermost negative electrode tab (200), and a projection of the barrier film (400) on the outermost positive electrode tab (100) is connected to the positive electrode lug (110) on the outermost positive electrode tab (100) in the first direction (X).
3. The battery cell of claim 1, wherein, The projection of the barrier film (400) on the outermost positive electrode tab (100) is spaced apart from the positive electrode lug (110) on the outermost positive electrode tab (100) in the first direction (X) by a distance D mm, and D is not greater than 5.
4. The battery cell of claim 1, wherein, The barrier film (400) has two first side edges (410) extending in the first direction (X) and two second side edges (420) extending in the second direction (Y), the second side edge (420) of the barrier film (400) close to the positive electrode lug (110) is flush with the edge of the outermost positive electrode tab (100) provided with the positive electrode lug (110), and the two ends of the second side edge (420) of the barrier film (400) close to the positive electrode lug (110) respectively extend beyond the connecting end of the positive electrode lug (110) in the second direction (Y) by a distance W1 mm, and W1 ranges from 1 to 30; and / or 5. The battery cell of claim 1, wherein, The first side edge (410) of the barrier film (400) in the first direction (X) has a size of W2 mm, and W2 ranges from 1 to 10. 6. The battery cell of claim 1, wherein, The blocking film (400) is semicircular or semi-elliptical, a straight edge of the blocking film (400) extends along the second direction (Y), the straight edge of the blocking film (400) is flush with an edge of the outermost positive pole piece (100) on which the positive pole lug (110) is arranged, and two ends of the straight edge of the blocking film (400) respectively extend beyond the connecting end of the positive pole lug (110) by W1 mm in the second direction (Y), wherein W1 is in a range of 1-30; and / or, A size of the blocking film (400) in the first direction (X) is W2 mm, and W2 is in a range of 1-10.
7. The battery cell of any one of claims 1-6, wherein, A thickness of the blocking film (400) is not greater than 50 μm.
8. The battery cell of any one of claims 1-6, wherein, The blocking film (400) is adhered to at least one of the negative pole piece (200), the positive pole piece (100) and the first diaphragm (310) by PVDF glue.
9. The battery cell of any one of claims 1-6, wherein, The blocking film (400) is at least one of a PP film, a PE film, a PET film, a PVC film and a nylon film.
10. The battery cell of any one of claims 1-6, wherein, The battery monomer further comprises a shell (50) and a cover plate (60), the shell (50) forms an accommodation cavity (510), the positive pole piece (100), the negative pole piece (200), the first diaphragm (310) and the second diaphragm (320) are arranged in the accommodation cavity (510), one end of the shell (50) in the first direction (X) has an opening, and the cover plate (60) is used for closing the opening.
11. A battery module, characterized by The battery monomer comprises any one of claims 1-10.
12. An electrical device, comprising: The battery module comprises claim 11.