Tab, battery cell and battery

Abstract

The utility model provides a tab, a battery cell and a battery, and relates to the technical field of batteries, the tab comprises an extension part and a connecting part, the extension part has preset length, width and thickness, the extension part is provided with an extension plane in the thickness direction, and the extension plane is used for connecting an external device; the connecting part has preset length, width and thickness, one end of the connecting part in the length direction is connected to one end of the extension part in the length direction, the connecting part is provided with a connecting plane in the thickness direction, and the connecting plane is used for connecting a pole piece; the width of the connecting part is smaller than that of the extending part, and the thickness of the connecting part is larger than that of the extending part. According to the tab, the battery cell and the battery disclosed by the embodiment of the utility model, the active substance content of the pole piece is increased while the connection strength of the tab and an external device is ensured, and the loss of the overcurrent capability of the tab is reduced.

Description

Technical Field

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

[0002] In related technologies, tabs are commonly used to transfer electrical energy from battery electrodes to external devices. To achieve the connection between the tab and the electrode, the electrode needs to be pre-cleaned using laser to remove active material from the current collector, allowing the tab to be directly welded to the current collector. However, laser cleaning of the active material leads to a decrease in the active material content of the electrode. Existing technologies reduce the area to be laser-cleaned by shrinking the tab size, thus increasing the active material content, but this results in insufficient current-carrying capacity of the tab and reduces the connection strength between the tab and external devices. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrode tab that, while ensuring the connection strength between the electrode tab and external devices, increases the active material content of the electrode plate and reduces the loss of the electrode tab's current carrying capacity.

[0004] This utility model also proposes a battery cell having the aforementioned tabs.

[0005] This utility model also proposes a battery having the above-mentioned battery cell.

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

[0007] The protrusion has a preset length, width, and thickness, and the protrusion has a protruding plane in the thickness direction, the protruding plane being used to connect to external devices;

[0008] The connecting part has a preset length, width and thickness. One end of the connecting part in the length direction is connected to one end of the protruding part in the length direction. The connecting part has a connecting plane in the thickness direction, and the connecting plane is used to connect the electrode. The width of the connecting part is smaller than the width of the protruding part, and the thickness of the connecting part is greater than the thickness of the protruding part.

[0009] The tab according to the embodiments of this utility model has at least the following beneficial effects: electrical energy on the electrode can enter the tab and flow to the outside along the length of the tab; when the protrusion with a preset length, width, and thickness is connected to an external device through the protruding plane, the connection strength between the tab and the external device and the current carrying capacity of the connection part itself can be guaranteed; since the connection part has a connecting plane in the thickness direction, and the connecting plane is used to connect the electrode, the size of the connection part in the width direction will affect the area of ​​the electrode that needs to be laser cleaned. Since the width of the connection part is smaller than the width of the protrusion, the area of ​​the laser cleaning area on the electrode that avoids the connection part is reduced, the active material of the electrode can be increased, and the decrease in current carrying capacity caused by the reduction in the width of the connection part can be compensated by the increase in thickness, thereby reducing the overall loss of current carrying capacity of the tab.

[0010] According to some embodiments of the present invention, the connecting portion further includes a first connecting segment and a second connecting segment arranged along its own length direction, the first connecting segment having the connecting plane; one end of the second connecting segment is connected to the first connecting segment, and the other end is connected to the protruding portion, the second connecting segment being disposed on the outside of the electrode sheet.

[0011] According to some embodiments of the present invention, the electrode tab further includes electrode tab adhesive, which is connected to the protruding portion.

[0012] According to some embodiments of this utility model, both the connecting part and the protruding part are cuboid structures.

[0013] According to some embodiments of the present invention, the thickness of the connecting portion is less than or equal to twice the thickness of the protruding portion.

[0014] According to some embodiments of the present invention, the width of the connecting portion is greater than or equal to half the width of the protruding portion.

[0015] The battery cell according to a second aspect embodiment of the present invention includes:

[0016] Electrodes, including current collectors;

[0017] As described in any of the above embodiments, the connecting portion is connected to the current collector on one side of the current collector in the thickness direction of the protruding portion.

[0018] The battery cell according to the embodiments of the present invention has at least the following beneficial effects: Since the width of the connecting part is smaller than the width of the protruding part, compared with the tabs whose widths are the same, the tabs of the present invention can reduce the area of ​​the laser cleaning region on the electrode sheet used to avoid the connecting part, increase the active material of the electrode sheet, and further increase the overall active material content of the battery cell. The decrease in current carrying capacity caused by the reduction in the width of the connecting part can be compensated by the increase in thickness, thereby reducing the loss of the overall current carrying capacity of the tab.

[0019] According to some embodiments of the present invention, the electrode further includes an active material coated on one side of the current collector in the thickness direction, wherein the minimum size of the active material in the thickness direction of the current collector is greater than the maximum size of the connecting portion.

[0020] According to some embodiments of the present invention, the connecting part is connected to the current collector by spot welding.

[0021] The battery according to a third aspect of the present invention includes a cell as described in any of the above embodiments.

[0022] The battery according to the embodiments of the present invention has at least the following beneficial effects: Since the width of the connecting part is smaller than the width of the protruding part, compared with the tabs whose widths are the same, the tabs of the present invention can reduce the area of ​​the laser cleaning region on the electrode sheet used to avoid the connecting part, increase the active material of the electrode sheet, and further increase the overall active material content of the battery. The decrease in current carrying capacity caused by the reduction in the width of the connecting part can be compensated by the increase in thickness, thereby reducing the loss of the overall current carrying capacity of the tab.

[0023] 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

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a front view schematic diagram of the electrode tabs according to some embodiments of the first aspect of this utility model;

[0026] Figure 2 for Figure 1 A side view of the middle pole ear;

[0027] Figure 3 for Figure 1 A schematic diagram showing the connection between the tabs and the electrode plates;

[0028] Figure 4 for Figure 3 Schematic diagram of the cross section at point AA;

[0029] Figure 5 This is a side view of the electrode tab of some embodiments of the second aspect of this utility model;

[0030] Figure 6 This is a front view schematic diagram of the electrode tabs according to some embodiments of the third aspect of this utility model;

[0031] Figure 7 This is a front view schematic diagram of the electrode tabs according to some embodiments of the fourth aspect of this utility model;

[0032] Figure 8 for Figure 7 A side view of the middle pole ear.

[0033] Figure label:

[0034] Electrode 10;

[0035] Extension 100, extension plane 110;

[0036] Connecting part 200, connecting plane 210, first connecting segment 220, second connecting segment 230;

[0037] Ear gel 300;

[0038] Transition section 400;

[0039] Electrode 20, current collector 21, active material 22, air gap 23. Detailed Implementation

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In existing technologies, to connect the tab to the electrode, laser cleaning is required to remove the active material adhering to the current collector of the electrode, exposing the current collector to the outside in the thickness direction, thus allowing the tab to connect to one side of the current collector in the thickness direction. It should be understood that removing the active material reduces the total amount of active material originally attached to the current collector, resulting in a decrease in the total electrical energy carried by the electrode. To avoid this, some existing solutions directly narrow the width or shorten the length of the tab, thereby reducing the total amount of active material that needs to be removed. However, these solutions significantly weaken the current-carrying capacity of the tab, making the battery more susceptible to damage and reducing its lifespan.

[0046] In view of this, please refer to Figure 1 , Figure 2 As shown, this utility model proposes a tab 10, which is used to draw out the electrical energy of the electrode 20 in the battery and to charge the external devices connected to the tab 10.

[0047] Please refer to Figure 1As shown, the tab 10 of this utility model includes a protruding part 100 and a connecting part 200 connected together. The protruding part 100 is used to connect to an external device, and the connecting part 200 is used to connect to the electrode 20. The electrical energy in the electrode 20 can flow to the external device through the connecting part 200 and the protruding part 100 in sequence, thereby charging the external device.

[0048] Both the protruding portion 100 and the connecting portion 200 of this invention have preset lengths, widths, and thicknesses. The protruding portion 100, with its preset length, width, and thickness, ensures the connection strength between the tab 10 and the external device, as well as the current-carrying capacity of the connecting portion 200 itself. Those skilled in the art can directly adjust the dimensions of the connecting portion 200 according to the connection requirements of the external device to ensure both the connection strength between the connecting portion 200 and the external device, and the current-carrying capacity of the connecting portion 200 itself.

[0049] It should be noted that the length, width and thickness of each structure mentioned in this utility model are only used as a directional reference and do not represent a specific size relationship between the length, width and thickness.

[0050] The protruding portion 100 of this invention has a protruding plane 110 for connecting external devices in its thickness direction, and the connecting portion 200 has a connecting plane 210 for connecting the electrode 20 in its thickness direction. One end of the connecting portion 200 in its length direction is connected to one end of the protruding portion 100 in its length direction. Through this design, the dimension of the connecting portion 200 in the width direction affects the area of ​​the electrode 20 that needs laser cleaning. When the width of the connecting portion 200 decreases, the area of ​​the electrode 20 that needs laser cleaning shrinks, the content of the active material 22 increases, and the current-carrying capacity of the connecting portion 200 decreases. When the width of the connecting portion 200 increases, the area of ​​the electrode 20 that needs laser cleaning increases, the content of the active material 22 decreases, and the current-carrying capacity of the connecting portion 200 increases.

[0051] The width of the connecting portion 200 of this invention is smaller than the width of the protruding portion 100, and the thickness of the connecting portion 200 is greater than the thickness of the protruding portion 100. Since the width of the connecting portion 200 is smaller than the width of the protruding portion 100, compared to the tab 10 with the same width as the protruding portion 100, the tab 10 of this invention allows for a reduction in the area of ​​the laser cleaning region on the electrode 20 used to avoid the connecting portion 200, increasing the amount of active material 22 on the electrode 20. Furthermore, the decrease in current-carrying capacity caused by the reduced width of the connecting portion 200 can be compensated for by the increased thickness, thereby reducing the overall loss of current-carrying capacity of the tab 10.

[0052] Without departing from the inventive concept of this utility model, those skilled in the art can make different adjustments to the orientation of the protrusion 100 and the connecting part 200 to adapt to different situations.

[0053] Please refer to Figures 1-4 As shown, where Figure 3 , Figure 4 right Figure 1 , Figure 2 The diagram illustrates the connection of the tab 10 to the electrode plate 20. In some embodiments, the length direction of the protrusion 100 is parallel to the length direction of the connecting portion 200 (i.e., Figures 1-4 (in the vertical direction), the width direction of the protruding part 100 is parallel to the width direction of the connecting part 200 (that is...) Figure 1 , Figure 3 (in the left-right direction), the thickness direction of the protruding part 100 is parallel to the thickness direction of the connecting part 200 (that is...) Figure 2 , Figure 4 (in the front-to-back direction); after the electrode 20 is connected to the connecting part 200, the protruding part 100 faces the width direction of the electrode 20 (that is, in the front-to-back direction); Figure 3 , Figure 4 It extends upwards (in the vertical direction).

[0054] In other embodiments, with Figure 1 , Figure 2 Taking the structure of the tab 10 shown as a reference, the protrusion 100 is bent at 90 degrees relative to the connecting portion 200 toward the connecting plane 210. The length direction of the protrusion 100 is parallel to the thickness direction of the connecting portion 200, the thickness direction of the protrusion 100 is parallel to the length direction of the connecting portion 200, and the width direction of the protrusion 100 is parallel to the width direction of the connecting portion 200. After the connecting portion 200 of the above embodiment is connected to the electrode 20, the protrusion 100 extends toward the thickness direction of the electrode 20 relative to the electrode 20.

[0055] Because the protruding plane 110 of the protruding part 100 has different orientations in the two embodiments described above, it can be used to connect external devices with different orientations. Those skilled in the art can make other adaptive adjustments to the orientation relationship between the protruding part 100 and the connecting part 200 without departing from the inventive concept of this utility model. All such adjustments are within the protection scope of this utility model.

[0056] Without departing from the inventive concept of this utility model, those skilled in the art can adjust the structure of the connecting part 200 and the protruding part 100. For example, please refer to... Figure 1As shown, in some embodiments, both the connecting portion 200 and the protruding portion 100 are semi-cylindrical structures. One end of the connecting portion 200 in the direction of its own axis extension is connected to one end of the protruding portion 100 in the direction of its own axis extension. The length direction of the connecting portion 200 is parallel to the direction of its own semi-cylindrical axis extension, and the plane of the semi-cylindrical body parallel to the axis is the connecting plane 210. The length direction of the protruding portion 100 is parallel to the direction of its own semi-cylindrical axis extension, and the plane of the semi-cylindrical body parallel to the axis is the protruding plane 110.

[0057] Please refer to Figure 1 , Figure 2 As shown, in some embodiments, both the connecting portion 200 and the protrusion 100 are cuboid structures, which is a preferred embodiment. The cuboid structure further simplifies the processing of the connecting portion 200 and the protrusion 100, thus reducing processing costs. Furthermore, since the connecting portion 200 is a cuboid structure, it also has a plane parallel to the connecting plane 210. This plane facilitates spot welding of the connecting portion 200 and the tab 10, further reducing the difficulty of spot welding and lowering production costs.

[0058] Please refer to Figure 5 As shown, in some embodiments, the protruding plane 110 is flush with the connecting plane 210. This design provides a unified reference for those skilled in the art when designing the thickness of the tab 10, simplifies the design of the tab 10, and reduces design and manufacturing costs.

[0059] Without departing from the inventive concept of this utility model, those skilled in the art can adjust the dimensions of the connecting part 200.

[0060] As a preferred option, please refer to Figure 1 , Figure 2 As shown, in some embodiments, the thickness of the connecting portion 200 is less than or equal to twice the thickness of the protruding portion 100. When the thickness of the connecting portion 200 is less than or equal to twice the thickness of the protruding portion 100, the weld point is more likely to penetrate the connecting portion 200 when the electrode 20 and the connecting portion 200 are connected by spot welding, thereby making the connecting portion 200 more firmly connected to the electrode 20, and thus ensuring the connection strength between the connecting portion 200 and the electrode 20.

[0061] As a preferred option, please refer to Figure 1 , Figure 2As shown, in some embodiments, the width of the connecting portion 200 is greater than or equal to half the width of the protrusion 100. When the width of the connecting portion 200 is greater than or equal to half the width of the protrusion 100, when the electrode 20 and the connecting portion 200 are connected by spot welding, the connecting portion 200 that meets the above requirements can provide more spot welding positions in the width direction, thereby making the connecting portion 200 more firmly connected to the electrode 20, and thus ensuring the connection strength between the connecting portion 200 and the electrode 20.

[0062] Please refer to Figure 3 , Figure 4 As shown, in some embodiments, the connecting portion 200 further includes a first connecting segment 220 and a second connecting segment 230 arranged along its own length direction. The first connecting segment 220 has a connecting plane 210; one end of the second connecting segment 230 is connected to the first connecting segment 220, and the other end is connected to the protrusion 100. The second connecting segment 230 is used to be disposed on the outside of the electrode 20. With the above solution, since the first connecting segment 220 and the second connecting segment 230 have the same shape, when the first connecting segment 220 is connected to the electrode 20 and an angular deviation occurs, when the protrusion 100 approaches the electrode 20, the portion of the protrusion 100 that protrudes relative to the first connecting segment 220 is less likely to contact the electrode 20, thereby reducing the possibility of the electrode 20 being punctured by the tab 10.

[0063] This utility model does not limit the connection form between the connecting part 200 and the protruding part 100. Please refer to... Figure 1 , Figure 2 As shown, in some embodiments, the connecting portion 200 is directly connected to the protruding portion 100.

[0064] Please refer to Figure 7 , Figure 8 As shown, in some embodiments, the tab 10 further includes a transition portion 400, through which the connecting portion 200 is indirectly connected to the protruding portion 100. One end of the transition portion 400 in its length direction (i.e., Figure 7 , Figure 8 The cross-sectional shape of the lower end shown is the same as the cross-sectional shape of the connecting part 200 perpendicular to the length direction of the connecting part 200. The other end of the transition part 400 in its own length direction (i.e. Figure 7 , Figure 8 The cross-sectional shape of the upper end (shown) is the same as the cross-sectional shape of the protrusion 100 perpendicular to its length direction, and the cross-sectional shape of the transition portion 400 gradually transitions from one end in the length direction to the shape of the other end in the length direction. Through this design, the transition portion 400 can reduce stress concentration caused by relative bending of the connecting portion 200 and the protrusion 100, thereby enhancing the connection strength between the connecting portion 200 and the protrusion 100 and improving the stability of the tab 10.

[0065] In the prior art, tab adhesive is commonly used to maintain insulation between the electrode sheet and the aluminum-plastic film. Without departing from the inventive concept of this utility model, those skilled in the art can adjust the position of the tab adhesive 300. As previously described, the connecting portion 200 includes embodiments with a first connecting segment 220 and a second connecting segment 230. In some embodiments, the tab adhesive 300 is connected to the second connecting segment 230.

[0066] As a preferred option, please refer to Figure 1 , Figure 2 , Figure 6 As shown, where Figure 6 In order to be in Figure 1 , Figure 2 A schematic diagram showing the tab adhesive 300 provided on the structure of the tab 10. In some embodiments, the tab 10 further includes the tab adhesive 300, which is connected to the protrusion 100. Providing the tab adhesive 300 to the protrusion 100 allows the tab 10 to be fixed to the aluminum-plastic film, thereby improving the strength of the connection portion 200. On the other hand, providing the tab adhesive 300 to the protrusion 100 prevents the portion of the protrusion 100 protruding relative to the connection portion 200 from being exposed to the outside of the battery after the tab adhesive 300 is connected to the aluminum-plastic film, thus reducing the risk of tearing of the protrusion 100 after being subjected to external impact.

[0067] Please refer to Figure 3 , Figure 4 As shown, this utility model also proposes a battery cell. The battery cell includes an electrode 20 and a tab 10 as in any of the above embodiments. The connecting portion 200 of the tab 10 is connected to one side of the current collector 21 in the thickness direction of the protrusion 100 on one side of the current collector 21 on the other side of the current collector 21 in the thickness direction of the protrusion 10. With the above solution, since the width of the connecting portion 200 is smaller than the width of the protrusion 100, compared with the tab 10 whose width is the same as the width of the connecting portion 200 and the protrusion 100, the tab 10 of this utility model can reduce the area of ​​the laser cleaning region on the electrode 20 used to avoid the connecting portion 200, increase the active material 22 of the electrode 20, and further increase the overall active material 22 content of the battery cell. The decrease in current carrying capacity caused by the reduction in the width of the connecting portion 200 can be compensated by the increase in thickness, thereby reducing the overall loss of current carrying capacity of the tab 10.

[0068] Please refer to Figure 3 , Figure 4 As shown, in some embodiments, the surface of the current collector 21 used to connect the connector 200 is further provided with a clearance zone 23, on which the active material 22 is removed. This solution further prevents the connector 200 from accidentally coming into direct contact with the active material 22 during production, thereby improving the safety performance of the battery cell.

[0069] Please refer to Figure 3 , Figure 4 As shown, in some embodiments, the electrode 20 further includes an active material 22 coated on one side of the current collector 21 in the thickness direction. In the thickness direction of the current collector 21, the minimum size of the active material 22 is larger than the maximum size of the connection portion 200. Through the above solution, when increasing the thickness of the connection portion 200 to enhance its current-carrying capacity, those skilled in the art can utilize the space occupied by the active material 22 in the thickness direction to increase the content of the active material 22 on the electrode 20 without increasing the overall thickness of the battery cell, thereby improving the energy density of the battery cell.

[0070] Furthermore, in some embodiments, the connecting portion 200 is connected to the current collector 21 by spot welding. Compared to other connection methods, spot welding has higher processing efficiency, which helps to reduce the production cost of the battery cell.

[0071] This invention also proposes a battery comprising the cell as described in any of the above embodiments. Since the width of the connecting portion 200 is smaller than the width of the protruding portion 100, compared to the tab 10, whose width is the same as the width of the connecting portion 200 and the protruding portion 100, the tab 10 of this invention allows for a reduction in the area of ​​the laser cleaning region on the electrode 20 used to avoid the connecting portion 200. This increases the amount of active material 22 on the electrode 20, further increasing the overall active material 22 content of the battery. Furthermore, the decrease in current-carrying capacity caused by the reduced width of the connecting portion 200 can be compensated for by increasing its thickness, thereby reducing the overall loss of current-carrying capacity of the tab 10.

[0072] 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. A tab, characterized in that, include: The protrusion has a preset length, width, and thickness, and the protrusion has a protruding plane in the thickness direction, the protruding plane being used to connect to external devices; The connecting part has a preset length, width and thickness. One end of the connecting part in the length direction is connected to one end of the protruding part in the length direction. The connecting part has a connecting plane in the thickness direction, and the connecting plane is used to connect the electrode. The width of the connecting part is smaller than the width of the protruding part, and the thickness of the connecting part is greater than the thickness of the protruding part.

2. The electrode tab according to claim 1, characterized in that, The connecting portion further includes a first connecting segment and a second connecting segment arranged along its own length direction. The first connecting segment has the connecting plane. One end of the second connecting segment is connected to the first connecting segment, and the other end is connected to the protrusion. The second connecting segment is used to be disposed on the outside of the electrode.

3. The electrode tab according to claim 1, characterized in that, The electrode tab also includes electrode tab adhesive, which is attached to the protrusion.

4. The electrode tab according to claim 1, characterized in that, Both the connecting part and the protruding part are rectangular parallelepiped structures.

5. The electrode tab according to claim 4, characterized in that, The thickness of the connecting portion is less than or equal to twice the thickness of the protruding portion.

6. The electrode tab according to claim 4, characterized in that, The width of the connecting part is greater than or equal to half the width of the protruding part.

7. A battery cell, characterized in that, include: Electrodes, including current collectors; According to any one of claims 1 to 6, the connecting portion is connected to the current collector on one side of the current collector in the thickness direction of the protrusion.

8. The battery cell according to claim 7, characterized in that, The electrode also includes an active material coated on one side of the current collector in the thickness direction. In the thickness direction of the current collector, the minimum size of the active material is greater than the maximum size of the connecting portion.

9. The battery cell according to claim 7, characterized in that, The connecting part is connected to the current collector by spot welding.

10. A battery, characterized in that, Includes the battery cell as described in any one of claims 7 to 9.

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