Battery cell, battery module and electric device
By setting a barrier film in the battery cell, lithium ions are prevented from depositing on the negative electrode, thus solving the lithium deposition problem and improving the reliability of the battery cell.
Patent Information
- Application Number
- CN202520351037.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-02-28
AI Technical Summary
In a single battery cell, the outermost negative electrode is prone to lithium plating in the area below the positive electrode tab, leading to lithium waste and reduced battery reliability.
A barrier film is placed between the outermost negative electrode and the positive electrode to prevent lithium ions from passing through and to prevent lithium from being deposited on the negative electrode.
By setting up a barrier film, lithium deposition on the negative electrode is prevented, thus improving the reliability of the battery cell.
Smart Images
Figure CN223898334U_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 stacked. 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 having intersecting first and third directions, the battery cell comprising:
[0007] An electrode assembly includes multiple positive electrode plates, multiple negative electrode plates, a separator, and a barrier film. The positive and negative electrode plates are alternately stacked along a third direction. The separator is disposed between adjacent positive and negative electrode plates. Along the third direction, the barrier film is disposed between the outermost adjacent positive and negative electrode plates. The barrier film is used to prevent lithium ions from passing through. Each positive electrode plate has a positive electrode tab at one end edge in a first direction. In the third direction, the projection of the barrier film on the outermost positive electrode plate is connected to or spaced apart from the positive electrode tab on the outermost positive electrode plate in the first direction.
[0008] In an optional embodiment, the barrier membrane is attached to at least one of the outermost negative electrode, the outermost positive electrode, and the separator between the outermost negative electrode and the outermost positive electrode.
[0009] 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.
[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 projection of the barrier film on 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 sheet is spaced apart from the positive electrode tab on the outermost positive electrode sheet in a first direction, and the spacing is D mm, where D is not greater than 5.
[0012] In an optional embodiment, the battery cell has a second direction intersecting the first direction, the barrier film has two first sides extending along the first direction and two second sides extending along the second direction, the second side of the barrier film near the positive electrode tab is flush with the edge of the outermost positive electrode sheet where the positive electrode tab is disposed, and the two ends of the second side of the barrier film near the positive electrode tab extend beyond the connection end of the positive electrode tab in the second direction by a dimension of 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 battery cell has a second direction intersecting the first direction; the barrier film is semi-circular or semi-elliptical; the straight edge of the barrier film extends along the second direction; the straight edge of the barrier film is flush with the edge of the outermost positive electrode sheet where the positive electrode tab is disposed; the two ends of the straight edge of the barrier film extend beyond the connection end of the positive electrode tab in the second direction by a dimension of 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 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 forming a receiving cavity, the electrode assembly being disposed within the receiving cavity, the housing having an opening at one end in a first direction, and the cover plate being used to close the opening.
[0020] Secondly, this application provides a battery module including any of the battery cells described in the foregoing embodiments.
[0021] Thirdly, this application provides an electrical device including the battery module of the aforementioned embodiments.
[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 has intersecting first and third directions. The battery cell includes an electrode assembly comprising multiple positive electrode plates, multiple negative electrode plates, a separator, and a barrier film. The positive and negative electrode plates are alternately stacked along the third direction. The separator is disposed between adjacent positive and negative electrode plates. Along the third direction, the barrier film is disposed between the outermost adjacent positive and negative electrode plates, and the barrier film is used to prevent lithium ions from passing through. Each positive electrode plate has a positive electrode tab at one end edge in the first direction. In the third direction, the projection of the barrier film onto the outermost positive electrode plate is either connected to or spaced apart from the positive electrode tab on the outermost positive electrode plate in the first direction. Due to the compression of the positive electrode tab, the outermost positive and negative electrode plates deform, creating a larger gap between them. This lengthens the lithium ion movement path, resulting in insufficient embedding on the outermost negative electrode plate. Ultimately, lithium is deposited on the surface of the negative electrode plate in the corresponding region below the positive electrode tab.
[0024] In this application, a barrier film is added between the outermost positive electrode and the negative electrode. The barrier film corresponds to the positive electrode below the positive electrode tab. This area is the main area where a large gap is formed between the outermost positive electrode and the negative electrode due to electrode deformation. The barrier film prevents lithium ions desorbed from the positive electrode in this area from moving to the negative electrode. Therefore, they cannot reach the corresponding area on the negative electrode, and lithium will not be deposited in the corresponding area on the negative electrode. This improves the problem of lithium deposition in the area below the positive electrode tab connection on the outermost negative electrode, and improves the reliability of the battery cell.
[0025] 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
[0026] 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.
[0027] Figure 1 This is a cross-sectional view of a battery cell in one embodiment of this application;
[0028] Figure 2 This is a schematic diagram of the electrode assembly of a battery cell in one embodiment of this application from a first-view perspective;
[0029] Figure 3This is a schematic diagram of the electrode assembly of a battery cell in one embodiment of this application from a second perspective;
[0030] Figure 4 A schematic diagram showing the application of a barrier film attached to the area on the outermost positive electrode connected to the connection end of the positive electrode tab in one embodiment of this application;
[0031] Figure 5 A 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.
[0032] Figure 6 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;
[0033] Figure 7 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;
[0034] Figure 8 This is a schematic diagram showing the application of a barrier film attached to the area on the outermost positive electrode that is connected to the connection end of the positive electrode tab in another embodiment of this application.
[0035] Icons: 100 - Positive electrode sheet; 101 - Outermost positive electrode; 110 - Positive electrode tab; 200 - Negative electrode sheet; 201 - Outermost negative electrode; 210 - Negative electrode tab; 300 - Separator; 400 - Barrier membrane; 410 - First side; 420 - Second side; 50 - Shell; 510 - Receiving cavity; 60 - Cover plate. Detailed Implementation
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.
[0041] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.
[0042] As described in the background section, the battery cells of this technology employ a stacked electrode 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 the edges of adjacent negative electrode sheets to deform as well. 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 it. 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.
[0043] To address this issue, this application provides a battery cell that uses a barrier film between the outermost negative electrode and the positive electrode. This barrier film prevents lithium ions released from the region below the positive electrode tab of the outermost positive electrode from transporting 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.
[0044] Figure 1 This is a cross-sectional view of a battery cell in one embodiment of this application; Figure 2This is a schematic diagram of the electrode assembly of a battery cell in one embodiment of this application from a first-view perspective; Figure 3 This is a schematic diagram of the electrode assembly of a battery cell in one embodiment of this application from a second perspective. The battery cell provided in this embodiment includes a housing 50, an electrode assembly, and a cover plate 60. The housing 50 forms a receiving cavity 510, and the electrode assembly is disposed within the receiving cavity 510. The electrode assembly includes a barrier film 400, alternatingly stacked positive electrode plates 100 and negative electrode plates 200, and a separator 300 disposed between adjacent positive electrode plates 100 and negative electrode plates 200. The barrier film 400 is located between the outermost adjacent positive electrode plates 100 and negative electrode plates 200, and the barrier film 400 is used to prevent lithium ions from passing through.
[0045] In this application, the battery cell has intersecting first direction X, second direction Y, and third direction Z; optionally, the first direction X, second direction Y, and third direction Z are mutually perpendicular. The electrode assembly includes multiple positive electrode plates 100 and multiple negative electrode plates 200, which are alternately stacked in the third direction Z. At least the outermost positive electrode plate 100 has a positive electrode tab 110 at one end edge in the first direction X; optionally, each positive electrode plate 100 has one positive electrode tab 110 at one end edge in the first direction X. Optionally, each negative electrode plate 200 has a negative electrode tab 210 at one end edge in the first direction. Optionally, the multiple positive electrode tabs 110 and the multiple negative electrode tabs 210 are spaced apart in the second direction. The projection of the barrier film 400 onto the outermost positive electrode 100 is either connected to or spaced apart from the positive electrode tab 110 on the outermost positive electrode 100 in the first direction X. In this embodiment, the housing 50 has an opening at one end in the first direction, and the cover plate 60 is used to close the opening of the housing 50. The end of the positive electrode 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 receiving cavity 510 of the housing 50 is parallel to the first direction X; the first direction X is the height direction of the electrode, the second direction Y is the width direction of the electrode, and the third direction Z is the thickness direction of the electrode.
[0046] It is understood that the electrode assembly provided in this application embodiment is a stacked structure, with a separator 300 disposed between each pair of adjacent electrodes. Multiple positive electrode plates 100 and multiple negative electrode plates 200 form an electrode array arranged in the third direction (Z). Optionally, the two electrodes at both ends of this electrode array in the third direction (Z) are both negative electrode plates 200. In other words, the number of negative electrode plates 200 is one more than the number of positive electrode plates 100. Optionally, the outermost two negative electrode plates 200 are also covered by a separator 300. In this application embodiment, each electrode plate is a flat sheet. Optionally, each pair of adjacent positive electrode plates 100 and negative electrode plates 200 is provided with an independent separator 300, and the electrode assembly is also provided with separators 300 at both ends in the third direction (Z), meaning the number of separators 300 is the number of electrodes plus one. In other alternative embodiments, the diaphragm 300 may also be folded in a Z-shape, with the diaphragm 300 having a bent section at the bend position and a straight section between other electrodes, with each positive electrode 100 and negative electrode 200 located between two straight sections of the diaphragm 300.
[0047] Optionally, both the positive electrode 100 and the negative electrode 200 are rectangular. The edge of the positive electrode 100 is parallel to the corresponding edge of the negative electrode 200. Two adjacent straight edges on the positive electrode 100 (or the negative electrode 200) are parallel to the first direction X and the second direction Y, respectively. Optionally, the edge on the positive electrode 100 used to set the positive electrode tab 110 extends along the second direction Y, and the edge on the negative electrode 200 used to set the negative electrode tab 210 is also a straight edge extending along the second direction Y. Optionally, the positive electrode 100 and the negative electrode 200 have the same size and their edges are flush. The second direction is perpendicular to the first direction and perpendicular to the depth direction of the receiving cavity 510 of the housing 50.
[0048] 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 separator 300 (specifically, the separator 300 between the outermost positive electrode 100 and the outermost negative electrode 200), or the barrier membrane 400 is located between the outermost adjacent negative electrode 200 and the separator 300 (specifically, the separator 300 between the outermost positive electrode 100 and the outermost negative electrode 200). For ease of description, in this application, the outermost positive electrode 100 of the electrode assembly is defined as the outermost positive electrode 101, and the outermost negative electrode 200 of the electrode assembly is defined as the outermost negative electrode 201; the outermost positive electrode 101 consists of two positive electrode 100s located at opposite ends in the third direction Z among the plurality of positive electrode 100s, and the outermost negative electrode 201 consists of two negative electrode 200s located at opposite ends in the third direction Z among the plurality of negative electrode 200s. Figure 2 , Figure 3 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.
[0049] Figure 4 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 5 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 separator 300. 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 5 Alternatively, it can be attached to the side of the outermost positive electrode 101 facing the outermost negative electrode 201 (e.g., Figure 4 Alternatively, the separator 300, which is attached between the outermost negative electrode 201 and the outermost negative electrode 201, can be attached to the side of the separator 300 facing the outermost positive electrode 101, or it can be attached to the side of the separator 300 facing the outermost negative electrode 201; or, the barrier membrane 400 is attached to both the outermost negative electrode 201 and the separator 300; or, the barrier membrane 400 is attached to both the outermost positive electrode 101 and the separator 300.
[0050] 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 tab 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 tab 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 the third direction Z. 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.
[0051] 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.
[0052] exist Figure 4 , Figure 5 In this embodiment, one side of the barrier film 400 in the first direction X is flush with the edge of the tab 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. Optionally, the projection of the barrier film 400 on the outermost positive electrode 101 is connected to the projection of the barrier film 400 on 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 projection of the barrier film 400 on the positive electrode tab 110 on the outermost positive electrode 100 in the first direction X. Optionally, in the first direction X, one side of the barrier membrane 400 extends beyond the outermost positive electrode 100 (i.e., the outermost positive electrode 101) and is provided with an edge connection end of the positive electrode tab 110.
[0053] Figure 6 This is a schematic diagram showing the gap between the edge of the barrier film 400 and the connection end of the positive electrode tab 110 on the outermost positive electrode 101 in one embodiment of this application. Figure 6 As 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.
[0054] like Figures 4 to 6As 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 prone to lithium plating 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 prone to lithium plating. 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.
[0055] 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.
[0056] In addition to using quadrilateral and rectangular barrier films 400, other shapes of barrier films 400 can also be used. Figure 7 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 8 This is a schematic diagram showing the application of a barrier film 400 attached to the area of the outermost positive electrode 101 connected to the connection end of the positive electrode tab 110 in another embodiment of this application. Figure 7 and Figure 8As 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.
[0057] 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 7 As 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.
[0058] 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.
[0059] 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.
[0060] Optionally, the barrier membrane 400 is bonded to at least one of the negative electrode 200, the positive electrode 100, and the separator 300 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 separator 300, and then the barrier membrane 400 is placed in the corresponding areas. The PVDF particles are 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 separator 300. 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 affects the hot-pressing interface of the electrode assembly.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] In summary, embodiments of this application provide a battery cell, a battery module, and a power-consuming device. The battery cell provided in this application includes an electrode assembly, which includes a barrier film 400, alternatingly stacked positive electrode plates 100 and negative electrode plates 200, and a separator 300 disposed between adjacent positive electrode plates 100 and negative electrode plates 200. The barrier film 400 is located between the outermost adjacent positive electrode plates 100 and negative electrode plates 200 and is used to prevent lithium ions from passing through. The battery cell has intersecting first and second directions. A positive electrode tab 110 is disposed at one edge of the positive electrode plate 100 in the first direction. The projection of the barrier film 400 onto the outermost positive electrode plate 100 is either connected to or spaced apart from the positive electrode tab 110 on the outermost positive electrode plate 100 in the first direction. The positive electrode tab 110 is squeezed, causing the outermost positive electrode 100 and the outermost negative electrode 200 to deform, creating a large gap between them. This makes the lithium ion movement path longer, resulting in insufficient embedding on the outermost negative electrode 200, and ultimately lithium is 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 area where a large gap is generated between the outermost positive electrode 100 and the negative electrode 200 due to electrode deformation. The barrier film 400 prevents lithium ions desorbed from the positive electrode 100 from moving to the negative electrode 200 in this area, thus preventing them from reaching the corresponding area on the negative electrode 200. As a result, lithium will not be 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.
[0065] 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.
[0066] 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 in that, Having intersecting first direction (X) and third direction (Z), the battery cell comprises: An electrode assembly includes multiple positive electrode plates (100), multiple negative electrode plates (200), a separator (300), and a barrier film (400). The positive electrode plates (100) and the negative electrode plates (200) are alternately stacked along a third direction (Z). The separator (300) is disposed between adjacent positive electrode plates (100) and negative electrode plates (200) along the third direction (Z). The barrier film (400) is disposed on the outermost adjacent positive electrode plate. Between the positive electrode (100) and the negative electrode (200), the barrier film (400) is used to prevent lithium ions from passing through; each positive electrode (100) has a positive electrode tab (110) at one end edge in the first direction (X), and in the third direction (Z), the projection of the barrier film (400) on the outermost positive electrode (100) is connected to or spaced apart from the positive electrode tab (110) on the outermost positive electrode (100) in the first direction (X).
2. The battery cell according to claim 1, characterized in that, The barrier membrane (400) is attached to at least one of the outermost negative electrode (200), the outermost positive electrode (100), and the separator (300) between the outermost negative electrode (200) and the outermost positive electrode (100).
3. The battery cell according to claim 1, characterized in that, The barrier film (400) is attached to the outermost negative electrode (200), and the projection of the barrier film (400) on the outermost positive electrode (100) is connected to the positive electrode tab (110) on the outermost positive electrode (100) in the first direction (X).
4. The battery cell according to claim 1, characterized in that, The barrier film (400) is attached to the outermost negative electrode (200), and the projection of the barrier film (400) on the outermost positive electrode (100) and the projection of the barrier film (400) on the positive electrode tab (110) on the outermost positive electrode (100) are connected in the first direction (X).
5. The battery cell according to claim 1, characterized in that, The projection of the barrier film (400) onto the outermost positive electrode plate (100) is spaced apart from the positive electrode tab (110) on the outermost positive electrode plate (100) in the first direction (X), with a spacing dimension of D mm, where D is not greater than 5.
6. The battery cell according to claim 1, characterized in that, Having a second direction (Y) intersecting the first direction (X), the barrier film (400) has two first sides (410) extending along the first direction (X) and two second sides (420) extending along the second direction (Y). The second side (420) of the barrier film (400) near the positive electrode tab (110) is flush with the edge of the outermost positive electrode sheet (100) where the positive electrode tab (110) is disposed. The two ends of the second side (420) of the barrier film (400) near the positive electrode tab (110) extend beyond the connection end of the positive electrode tab (110) in the second direction (Y) by a dimension of W1 mm, where W1 ranges from 1 to 30 mm; and / or, The first side (410) of the barrier membrane (400) has a dimension of W2 mm in the first direction (X), where W2 ranges from 1 to 10.
7. The battery cell according to claim 1, characterized in that, Having a second direction (Y) intersecting the first direction (X), the barrier film (400) is semi-circular or semi-elliptical, with its straight edge extending along the second direction (Y). The straight edge of the barrier film (400) is flush with the edge of the positive electrode tab (110) on the outermost positive electrode plate (100). The two ends of the straight edge of the barrier film (400) extend beyond the connection end of the positive electrode tab (110) in the second direction (Y) by a dimension of W1 mm, where W1 ranges from 1 to 30 mm; and / or, The size of the barrier membrane (400) in the first direction (X) is W2 mm, and W2 ranges from 1 to 10.
8. The battery cell according to any one of claims 1-7, characterized in that, The thickness of the barrier film (400) is no greater than 50 μm.
9. The battery cell according to any one of claims 1-7, characterized in that, The barrier membrane (400) is bonded to at least one of the negative electrode (200), the positive electrode (100), and the separator (300) by PVDF adhesive.
10. The battery cell according to any one of claims 1-7, characterized in that, The barrier film (400) is at least one of PP film, PE film, PET film, PVC film and nylon film.
11. The battery cell according to any one of claims 1-7, characterized in that, The battery cell also includes a housing (50) and a cover plate (60). The housing (50) forms a receiving cavity (510), and the electrode assembly is disposed in the receiving cavity (510). The housing (50) has an opening at one end in the first direction (X), and the cover plate (60) is used to close the opening.
12. A battery module, characterized in that, Includes the battery cell according to any one of claims 1-11.
13. An electrical appliance, characterized in that, Includes the battery module as described in claim 12.