Pole piece, battery cell and battery pack

Abstract

The application discloses a pole piece, a battery cell and a battery pack. The pole piece comprises a current collector, a pole lug, a first insulating layer and a second insulating layer. The current collector has a first direction and a second direction perpendicular to each other. The pole lug is protruded from the current collector along the first direction. The pole lug has a first surface and a second surface oppositely arranged along the second direction. The first insulating layer covers part of the first surface. The second insulating layer covers at least part of the second surface. An end of the second insulating layer away from the current collector exceeds an end of the first insulating layer away from the current collector. The part of the second insulating layer exceeding the first insulating layer can improve the insulation performance of the pole lug, and can reduce the possibility of short circuit caused by the pole lug being inserted into the battery cell when being bent. Compared with the case where the insulating layers on both sides of the pole lug have the same height, the mode that the insulating layer on one side of the pole lug exceeds the insulating layer on the other side can also reduce the bending difficulty of the pole lug, reduce the occupied top space of the battery cell, and improve the energy density of the battery cell.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to an electrode, a battery cell, and a battery pack. Background Technology

[0002] In related technologies, existing lithium-ion batteries are typically composed of a core, a casing, a top cover, and an electrolyte. Multiple tabs are led out from one or both ends of the core. After the core is rolled up, the multiple tabs form a multi-layer tab. The multi-layer tabs need to be bundled together and then placed parallel to the top cover, so that the tabs are directly or indirectly welded to the terminals so that the current can be led out of the cell.

[0003] During final assembly, the axis of the core is perpendicular to the surface of the top cover. This causes the multi-layer tabs to bend. The bending curvature and stress of the inner and outer layers of the multi-layer tabs are different, which may cause the tabs to be inserted into the core after manufacturing, causing an internal short circuit.

[0004] Therefore, to solve this problem, existing electrodes are generally coated with a ceramic coating of the same height on both sides. The ceramic coating can protect the electrode when it is inserted, thus reducing the likelihood of short circuits. However, the ceramic coating on both sides of the electrode increases the difficulty of bending the electrode, which may prevent the electrode from bending properly. In addition, the ceramic coating also occupies the top space of the cell, reducing the energy density of the cell. Utility Model Content

[0005] This application aims to provide an electrode, a battery cell, and a battery pack that can solve the problem that the ceramic coating on both sides of the electrode increases the difficulty of bending the electrode, which may cause the electrode to be unable to bend normally. Moreover, the ceramic coating also occupies the top space of the battery cell, reducing the energy density of the battery cell.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows:

[0007] In a first aspect, embodiments of this application propose an electrode sheet, including a current collector, a tab, a first insulating layer, and a second insulating layer. The current collector has a first direction and a second direction that are perpendicular to each other. The tab protrudes from the current collector along the first direction. The tab has a first surface and a second surface that are disposed opposite to each other along the second direction. The first insulating layer covers a portion of the first surface, and the second insulating layer covers at least a portion of the second surface. One end of the second insulating layer away from the current collector extends beyond the other end of the first insulating layer away from the current collector.

[0008] Optionally, the current collector has a first side and a second side opposite to each other along the second direction, the first side corresponding to the first surface;

[0009] The first insulating layer includes a first sub-insulating portion and a second sub-insulating portion that are interconnected. The first sub-insulating portion covers the edge portion of the first side near the electrode tab, and the second sub-insulating portion covers a portion of the first surface.

[0010] The second insulating layer includes a third sub-insulating portion and a fourth sub-insulating portion that are interconnected, the third sub-insulating portion covering the edge portion of the second side near the tab, and the fourth sub-insulating portion covering at least a portion of the second surface;

[0011] Along the first direction, the end of the fourth sub-insulator away from the current collector extends beyond the end of the second sub-insulator away from the current collector.

[0012] Optionally, the current collector further has a third direction, which is perpendicular to the first direction and the second direction, and the portion of the fourth sub-insulator extending beyond the second sub-insulator is provided as a protrusion, wherein the protrusion has a groove extending along the third direction.

[0013] Optionally, there may be a plurality of grooves, and the plurality of grooves are arranged at intervals along the first direction.

[0014] Optionally, the groove extends through the protrusion along the second direction.

[0015] Optionally, the groove extends through the protrusion along the third direction.

[0016] Optionally, along the first direction, the fourth sub-insulator portion is a continuously extending structure.

[0017] Optionally, the second insulating layer extends from the first insulating layer along the first direction by a length of 1 mm to 20 mm.

[0018] Secondly, embodiments of this application provide a battery cell including a housing and an electrode assembly. The housing has a receiving cavity, and the electrode assembly is disposed in the receiving cavity. The electrode assembly is formed by stacking or winding electrode sheets. At least a portion of the electrode sheets in the electrode assembly adopts the electrode sheets of any of the above embodiments.

[0019] Optionally, the battery cell includes at least two electrode assemblies arranged side by side. Along the side-by-side direction of the at least two electrode assemblies, the housing includes two opposing sidewalls. The electrode assembly closer to the sidewall is the first electrode assembly. The height direction of the battery cell is the first direction. The first electrode assembly has a central axis extending along the first direction. The electrode in the first electrode assembly located on the side of the central axis closer to the sidewall adopts the electrode of any of the above embodiments.

[0020] Optionally, the electrode located on the side of the central axis near the shell sidewall is designated as the target electrode, the electrode tab on the target electrode is designated as the target electrode tab, and the surface of the target electrode tab facing away from the shell sidewall is provided with the second insulating layer.

[0021] Optionally, the electrode assembly includes a cell body and the tab. The tab includes a first connecting segment, a second connecting segment, and a bending portion. The first connecting segment and the second connecting segment are bent together to form a bending portion between the first connecting segment and the second connecting segment. The first connecting segment is used to connect to the cell body, and the second connecting segment is used to connect to the electrode post. The portion of the second insulating layer that extends beyond the first insulating layer is located in the bending portion.

[0022] Thirdly, embodiments of this application propose a battery pack that includes the electrode sheets of any of the above embodiments, or the battery cells of any of the above embodiments.

[0023] In the embodiments of this application, a first insulating layer and a second insulating layer are respectively provided on the first and second surfaces opposite to the tab, and the end of the second insulating layer facing away from the current collector extends beyond the end of the first insulating layer facing away from the current collector. That is, the distance between the end of the second insulating layer facing away from the current collector and the current collector is greater than the distance between the end of the first insulating layer facing away from the current collector and the current collector. Insulating layers are provided on both sides of the tab, which can protect the tab. When the electrode is assembled into the cell, it needs to be bent to connect with the terminal. The portion of the second insulating layer that extends beyond the first insulating layer can improve the insulation performance of the tab, reduce the possibility of short circuit when the tab is inserted into the cell during bending. Compared with the case where the insulating layers on both sides of the tab are of the same height, the way the insulating layer on one side of the tab extends beyond the insulating layer on the other side in the embodiments of this application can also reduce the bending difficulty of the tab, reduce the space occupied on the top of the cell, and improve the energy density of the cell.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below, wherein:

[0026] Figure 1 This is a schematic diagram of the front view structure of the electrode sheet provided in the first embodiment of this application;

[0027] Figure 2This is a cross-sectional structural diagram of the electrode sheet provided in the first embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the front view structure of the electrode sheet provided in the second embodiment of this application;

[0029] Figure 4 A cross-sectional view of the electrode sheet provided in the second embodiment of this application;

[0030] Figure 5 This is a cross-sectional structural diagram of the battery cell provided in an embodiment of this application.

[0031] Figure label:

[0032] 100, Current collector; 110, First side; 120, Second side; 200, Tab; 210, First surface; 220, Second surface; 250, First connecting section; 260, Second connecting section; 270, Bending portion; 300, First insulating layer; 310, First sub-insulating portion; 320, Second sub-insulating portion; 400, Second insulating layer; 410, Third sub-insulating portion; 420, Fourth sub-insulating portion; 421, Protrusion; 440, Groove; 500, Active material layer; 601, Shell sidewall; 610, Receiving cavity; 700, Electrode assembly; X, First direction; Y, Second direction; Z, Third direction; A, First dashed line; B, Second dashed line; C, Central axis. Detailed Implementation

[0033] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated 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 application, and should not be construed as limiting this 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.

[0034] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, 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.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] The electrode sheets, cells, and battery packs provided in this application will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0038] like Figure 1 and Figure 2 As shown, an electrode sheet according to some embodiments of this application includes a current collector 100, a tab 200, a first insulating layer 300, and a second insulating layer 400. The current collector 100 has a first direction X and a second direction Y that are perpendicular to each other. The tab 200 protrudes from the current collector 100 along the first direction X. The tab 200 has a first surface 210 and a second surface 220 that are disposed opposite to each other along the second direction Y. The first insulating layer 300 covers a portion of the first surface 210, and the second insulating layer 400 covers at least a portion of the second surface 220. One end of the second insulating layer 400 away from the current collector 100 extends beyond the end of the first insulating layer 300 away from the current collector 100.

[0039] In this embodiment, the first surface 210 and the second surface 220 of the electrode 200 are respectively provided with a first insulating layer 300 and a second insulating layer 400. The end of the second insulating layer 400 facing away from the current collector 100 extends beyond the end of the first insulating layer 300 facing away from the current collector 100. That is, the distance between the end of the second insulating layer 400 facing away from the current collector 100 and the current collector 100 is greater than the distance between the end of the first insulating layer 300 facing away from the current collector 100 and the current collector 100. When the electrode is assembled into the battery cell, it needs to be bent to connect with the terminal post. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 can improve the insulation performance of the tab 200, thereby reducing the possibility of a short circuit when the tab 200 is bent and inserted into the battery cell. Compared to the case where insulating layers of the same height are provided on both sides of the tab 200, the way in this embodiment of the application where the insulating layer on one side of the tab 200 extends beyond the insulating layer on the other side can also reduce the bending difficulty of the tab 200, reduce the space occupied on the top of the battery cell, and improve the energy density of the battery cell.

[0040] Specifically, the electrode provided in this application embodiment can be applied to a battery cell, which can be a wound battery cell or a stacked battery cell. The battery cell is applied to a battery, which can be a lithium-ion battery.

[0041] Among them, such as Figure 2 As shown, the current collector 100 is a component used to manufacture the core, and its material can be aluminum, copper, or composite materials. For example, the positive electrode current collector 100 of the battery can be aluminum foil, and the negative electrode current collector 100 of the battery can be copper foil. The current collector 100 has a first direction X and a second direction Y that are perpendicular to each other. The first direction X can be the height direction of the current collector 100, and the second direction Y can be the thickness direction of the current collector 100.

[0042] like Figure 1 and Figure 2 As shown, the tab 200 protrudes from the current collector 100 along the first direction X. The current collector 100 and the tab 200 are separated by the second dashed line B. The tab 200 has a first surface 210 and a second surface 220 arranged opposite to each other along the second direction Y. The first surface 210 and the second surface 220 are two surfaces in the thickness direction of the tab 200.

[0043] like Figure 1 and Figure 2 As shown, the first insulating layer 300 covers a portion of the first surface 210, such that a portion of the first surface 210 is covered. The second insulating layer 400 covers at least a portion of the second surface 220, such that a portion of the second surface 220 is covered or the entire second surface 220 is covered.

[0044] like Figure 1 and Figure 2As shown, the end of the second insulating layer 400 facing away from the current collector 100 extends beyond the end of the first insulating layer 300 facing away from the current collector 100. The first dashed line A is the boundary line in the second insulating layer 400 that is flush with the end of the first insulating layer 300 facing away from the current collector 100, so that along the first direction X, the second insulating layer 400 is higher than the first insulating layer 300. When the bending region of the tab 200 is located in the part where the second insulating layer 400 is higher than the first insulating layer 300, the bending region has only one insulating layer, reducing the difficulty of bending the tab 200.

[0045] In addition, compared with the case where the height of the insulating layers on both sides is the same in the related technology, the height of the first insulating layer 300 in this application embodiment is lower than that of the second insulating layer 400, which makes the first insulating layer 300 require less material and reduces the manufacturing cost.

[0046] For example, the material of the first insulating layer 300 can be a ceramic material, such as one or more of boehmite, alumina and its modified oxides, and titanium dioxide and its modified oxides; the material of the first insulating layer 300 can also be an organic insulating material, such as PE (polyethylene), PP (polypropylene), PI (polyimide), and PET (polyethylene terephthalate). Of course, the first insulating layer 300 can be flexibly set according to the actual situation, and this application embodiment does not limit it in this way. Similarly, the material of the second insulating layer 400 can also be a ceramic material or an organic insulating material, and the material of the second insulating layer 400 can be the same as or different from the material of the first insulating layer 300.

[0047] Optionally, such as Figure 1 and Figure 2 As shown, the current collector 100 has a first side 110 and a second side 120 opposite to each other along the second direction Y. The first side 110 corresponds to the first surface 210. The first insulating layer 300 includes a first sub-insulating portion 310 and a second sub-insulating portion 320 connected to each other. The first sub-insulating portion 310 covers the edge portion of the first side 110 near the tab 200. The second sub-insulating portion 320 covers a portion of the first surface 210. The second insulating layer 400 includes a third sub-insulating portion 410 and a fourth sub-insulating portion 420 connected to each other. The third sub-insulating portion 410 covers the edge portion of the second side 120 near the tab 200. The fourth sub-insulating portion 420 covers at least a portion of the second surface 220. Along the first direction X, the end of the fourth sub-insulating portion 420 away from the current collector 100 extends beyond the end of the second sub-insulating portion 320 away from the current collector 100.

[0048] In this embodiment, both the first insulating layer 300 and the second insulating layer 400 simultaneously cover the current collector 100 and the tab 200, thus providing simultaneous protection for both. The area of ​​the second insulating layer 400 extending beyond the first insulating layer 300 is located on the tab 200. This extension improves the insulation performance of the tab 200, reducing the likelihood of a short circuit when the tab 200 is bent and inserted into the battery cell. Compared to cases where insulating layers of uniform height are provided on both sides of the tab 200, the extension of one side of the tab 200 beyond the other in this embodiment reduces the bending difficulty of the tab 200, minimizes the space occupied at the top of the battery cell, and increases the energy density of the battery cell.

[0049] Specifically, such as Figure 1 and Figure 2 As shown, the current collector 100 has a first side 110 and a second side 120 opposite to each other along its thickness direction. A first insulating layer 300 includes a first sub-insulating portion 310 and a second sub-insulating portion 320 interconnected. The first sub-insulating portion 310 covers the edge portion of the first side 110 near the tab 200, and the second sub-insulating portion 320 covers a portion of the first surface 210, thus simultaneously protecting both the first side 110 of the current collector 100 and the first surface 210 of the tab 200. A second insulating layer 400 includes a third sub-insulating portion 410 and a fourth sub-insulating portion 420 interconnected. The third sub-insulating portion 410 covers the edge portion of the second side 120 near the tab 200, and the fourth sub-insulating portion 420 covers a portion or all of the second surface 220, thus simultaneously protecting both the second side 120 of the current collector 100 and the second surface 220 of the tab 200. Along the first direction X, the end of the fourth sub-insulating portion 420 away from the current collector 100 extends beyond the end of the second sub-insulating portion 320 away from the current collector 100.

[0050] In addition, such as Figure 1 and Figure 2 As shown, the first side 110 and the second side 120 of the current collector 100 are also covered with an active material layer 500, which is the main body for storing and releasing lithium ions in the electrode, and will not be described in detail here.

[0051] Optionally, such as Figure 3 and Figure 4 As shown, the current collector 100 also has a third direction Z, which is perpendicular to the first direction X and the second direction Y. The portion of the fourth sub-insulating portion 420 that extends beyond the second sub-insulating portion 320 is provided as a protrusion 421, and the protrusion 421 is provided with a groove 440 extending along the third direction Z.

[0052] In this embodiment of the application, by providing a groove 440 extending in the third direction Z in the protrusion 421, bending deformation is facilitated from the groove 440 when the tab 200 is bent, thereby reducing the difficulty of bending the tab 200 and further improving the bendability of the tab 200.

[0053] Specifically, such as Figure 3 and Figure 4 As shown, the current collector 100 also has a third direction Z, which is perpendicular to the first direction X and the second direction Y. The third direction Z can be the length direction of the current collector 100. When the tab 200 is bent, it is bent around the axis extending along the third direction Z. The groove 440 extending along the third direction Z can reduce the difficulty of bending.

[0054] It should be noted that the first direction X, the second direction Y, and the third direction Z are mutually perpendicular. Specifically, this can be "perpendicular" in the strict sense, for example, the angle between the first direction X and the second direction Y is 90°; or it can be "approximately perpendicular," specifically meaning that the angle between any two of the first direction X, the second direction Y, and the third direction Z includes a certain error. Considering the measurement and the error associated with the measurement of a specific quantity (i.e., the limitations of the measurement system), this error is within the acceptable deviation range for a specific value as determined by a person skilled in the art. For example, the angle between the first direction X and the second direction Y is 90° ± 5°.

[0055] Optionally, such as Figure 3 and Figure 4 As shown, there are multiple grooves 440, and the multiple grooves 440 are arranged at intervals along the first direction X.

[0056] In this embodiment of the application, by providing multiple grooves 440, the thickness of the protrusion 421 can be reduced from multiple positions, further reducing the difficulty of bending the tab 200 and further improving the bendability of the tab 200.

[0057] Optionally, such as Figure 3 and Figure 4 As shown, the groove 440 penetrates the protrusion 421 along the second direction Y.

[0058] In this embodiment, the groove 440 extends through the protrusion 421 along the second direction Y. The groove 440 is not covered with an insulating layer, which better reduces the difficulty of bending the tab 200.

[0059] Optionally, such as Figure 3 and Figure 4 As shown, the groove 440 penetrates the protrusion 421 along the third direction Z.

[0060] In this embodiment, the groove 440 penetrates the protrusion 421 along the third direction Z, thereby reducing the thickness of the insulating layer of the protrusion 421 from one end to the other along the third direction Z at the groove 440, which better reduces the difficulty of bending the tab 200.

[0061] Specifically, in the first embodiment, there are multiple grooves 440, which are spaced apart along the first direction X. In the second embodiment, the grooves 440 penetrate the protrusion 421 along the second direction Y. In the third embodiment, the grooves 440 penetrate the protrusion 421 along the third direction Z.

[0062] It should be noted that the specific form of the groove 440 can be any one of these three embodiments or at least two of them.

[0063] Optionally, such as Figure 1 and Figure 2 As shown, the fourth sub-insulating part 420 has a continuous extending structure along the first direction X.

[0064] In this embodiment, the fourth sub-insulating portion 420 extends continuously along the first direction X, and there are no gaps in the area covered by the fourth sub-insulating portion 420 corresponding to the second surface 220 of the tab 200, which provides better protection for the tab 200.

[0065] Specifically, such as Figure 1 and Figure 2 As shown, the fourth sub-insulating portion 420 is formed into a continuously extending structure along the first direction X, such as a continuous coating structure, a continuous spraying structure, or a continuous pasting structure. Of course, the specific structure of the fourth sub-insulating portion 420 can be flexibly configured according to actual conditions, and this embodiment does not limit this. Similarly, the fabrication of the first sub-insulating portion 310, the second sub-insulating portion 320, and the third sub-insulating portion 410 can also be flexibly configured according to actual conditions, and this embodiment does not limit this.

[0066] Optionally, the second insulating layer 400 extends from the first insulating layer 300 along the first direction X by a length of 1 mm to 20 mm.

[0067] In this embodiment, compared to the case where the excess length (i.e., the height of the protrusion 421) is less than 1 mm, the excess length in this range is larger, providing a greater operating length and making it easier to bend the tab 200. The end of the tab 200 away from the current collector 100 is used to connect with adjacent tabs 200 to form a tab bundle, and to connect with the terminal of the battery cell. Compared to the case where the excess length is greater than 20 mm, the excess length in this range is smaller, allowing more length to be reserved for connecting adjacent tabs 200 and connecting with the terminal, avoiding affecting the connection performance of the tab bundle and the connection performance between the tab bundle and the terminal. At the same time, the material of the second insulating layer 400 in the excess area is less, resulting in lower manufacturing costs.

[0068] Specifically, the minimum excess length should be sufficient to ensure adequate operating length for bending the tab 200, while the maximum excess length can be 20mm.

[0069] In some embodiments, by using electrode sheets of different specifications to manufacture the battery cell, Hi-pot defects due to insertion of the tab 200 can be detected through Hi-pot testing. The electrode sheets of different specifications are identical in structure except for the height of the protrusion 421. Specific test results are as follows:

[0070] Table 1

[0071]

[0072]

[0073] Hi-pot defect rate is obtained from Hi-pot testing. Hi-pot testing is a key quality inspection process after the bare cell completes subsequent assembly. Its main purpose is to detect whether there are foreign particles inside the cell, whether the separator is damaged, or whether there are serious burrs on the edge of the electrode, which may cause internal short circuits in the lithium battery, thus ensuring the safety of the lithium battery in use.

[0074] Hi-pot testing involves applying a DC voltage higher than the normal operating voltage (e.g., 500V) between the positive and negative terminals of a bare battery cell using an insulation resistance tester. This voltage is maintained for a period of time, and the leakage current is detected by a detector to confirm whether there is a short circuit inside the cell (internal insertion of tab 200 is one of the causes of internal short circuits). When the leakage current exceeds a set threshold, the cell is identified as defective. The defective cell is then disassembled to analyze the cause of the defect, and the number of cells with Hi-pot defects due to tab 200 insertion is counted. Dividing this number by the total number of cells tested yields the Hi-pot defect rate due to tab insertion.

[0075] Based on the experimental data in Table 1, comparing the data of experimental groups 1 to 12 with the data of control group 1, it can be seen that as the height of the protrusion 421 increases, the defect rate of the Hi-pot inserted into the tab 200 gradually decreases, and the greater the increase in the height of the protrusion 421, the greater the decrease in the defect rate of the Hi-pot inserted into the tab 200. However, the greater the length of the second insulating layer 400 beyond the first insulating layer 300 (i.e., the height of the protrusion 421), the more the second insulating layer 400 covers the tab 200, which may affect the connection performance of adjacent tabs 200. Therefore, in the embodiments of this application, 20mm is taken as the maximum value. In addition, comparing the data of experimental group 10 with the data of control group 5, it can be seen that when the height of the second insulating layer 400 is 20mm, the defect rate of the Hi-pot inserted into the tab 200 is basically the same. The height of the first insulating layer 300 in experimental group 10 is 3mm, and the height of the first insulating layer in control group 5 is 20mm. Experimental group 10 has only one insulating layer in the area of ​​the protrusion 421, which can reduce the bending difficulty.

[0076] In summary, this embodiment of the application, which features an inconsistent height of the insulating layers on both sides, can reduce the failure rate of Hi-pot due to the insertion of the tab 200, and also reduce the difficulty of bending the tab 200.

[0077] like Figure 5 As shown, this application also proposes a battery cell, including a housing and an electrode assembly 700. The housing has a receiving cavity 610, and the electrode assembly 700 is disposed in the receiving cavity 610. The electrode assembly 700 is formed by stacking or winding electrode sheets. At least some of the electrode sheets in the electrode assembly 700 adopt the electrode sheets of any of the above embodiments.

[0078] In this embodiment, since at least some of the electrodes in the electrode assembly 700 are electrodes from any of the above embodiments, they need to be bent when assembled into the battery cell to connect with the terminal post. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 can improve the insulation performance of the tab 200, thereby reducing the possibility of a short circuit when the tab 200 is bent and inserted into the battery cell. Compared to the case where insulating layers of the same height are provided on both sides of the tab 200, the way the insulating layer on one side of the tab 200 extends beyond the insulating layer on the other side in this embodiment can also reduce the bending difficulty of the tab 200, reduce the space occupied on the top of the battery cell, and improve the energy density of the battery cell.

[0079] Specifically, such as Figure 5 As shown, the housing is a component that protects the battery cell. The electrode assembly 700 can be made by stacking or winding positive electrode plates, negative electrode plates and a separator. At least some of the electrode plates (here, it can be at least one of the positive electrode plate and the negative electrode plate) adopt the electrode plates of any of the above embodiments.

[0080] Optionally, such as Figure 5 As shown, the battery cell includes at least two electrode assemblies 700 arranged side by side. Along the side-by-side direction of the at least two electrode assemblies 700, the housing includes two opposing housing sidewalls 601. The electrode assembly closer to the housing sidewall 601 is the first electrode assembly. The height direction of the battery cell is a first direction X. The first electrode assembly has a central axis C extending along the first direction X. The central axis C can be a centerline passing through the center of the first electrode assembly along the first direction X. The electrode in the first electrode assembly located on the side of the central axis C closer to the housing sidewall 601 adopts the electrode of any of the above embodiments.

[0081] In this embodiment, since the electrode located on the side of the central axis C near the shell sidewall 601 has a greater degree of bending than the electrode located on the side of the central axis C away from the shell sidewall 601, the electrode located on the side of the central axis C near the shell can reduce the bending difficulty of the electrode by adopting the electrode of any of the above embodiments, and reduce the possibility of short circuit when inserting the battery cell into the electrode.

[0082] Specifically, such as Figure 5 As shown, the battery cell includes at least two electrode assemblies 700, with tabs of the two electrode assemblies 700 connected to the same terminal post. Each electrode assembly 700 has a side closer to the terminal post and a side farther from the terminal post. The side of the electrode assembly 700 farther from the terminal post can be understood as the side closer to the housing sidewall 601. The electrode sheet located on the side of the central axis C closer to the housing sidewall 601 can partially or entirely use the electrode sheets from any of the above embodiments. The electrode sheets located on the side of the central axis C closer to the housing sidewall 601 are farther from the center of the housing, and have a greater degree of bending. Using the electrode sheets from any of the above embodiments can reduce the possibility of a short circuit when the battery cell is inserted into the electrode sheet.

[0083] Optionally, the electrode located on the side of the central axis C near the shell sidewall 601 is designated as the target electrode, the tab 200 provided on the target electrode is designated as the target tab 200, and the surface of the target tab 200 facing away from the shell sidewall 601 is provided with a second insulating layer 400.

[0084] In this embodiment, the tab 200 on the target electrode is bent towards the sidewall 601 of the housing. The concave area of ​​the bend is located on the surface away from the sidewall 601. By providing a second insulating layer 400 in the concave area, the electrode needs to be bent when assembled into the cell to connect with the terminal post. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 can improve the insulation performance of the tab 200, thereby reducing the possibility of a short circuit when the tab 200 is inserted into the cell during bending. Compared to the case where insulating layers of the same height are provided on both sides of the tab 200, the way the insulating layer on one side of the tab 200 extends beyond the insulating layer on the other side in this embodiment can also reduce the bending difficulty of the tab 200, reduce the space occupied on the top of the cell, and improve the energy density of the cell.

[0085] Specifically, the electrode plate located on the side of the central axis C near the shell sidewall 601 is bent toward the sidewall 601, and the concave area of ​​the bend is on the surface away from the sidewall 601. A second insulating layer 400 is provided in the concave area.

[0086] Optionally, such as Figure 5 As shown, the electrode assembly 700 includes a cell body and a tab 200. The tab 200 includes a first connecting section 250, a second connecting section 260, and a bending portion 270. The first connecting section 250 and the second connecting section 260 are bent together to form the bending portion 270 between the first connecting section 250 and the second connecting section 260. The first connecting section 250 is used to connect with the cell body, and the second connecting section 260 is used to connect with the electrode post. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 is located in the bending portion 270.

[0087] In this embodiment, the bending portion 270 is bent, and it is close to the battery cell body. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 is located in the bending portion 270, which can protect the bending portion 270 and reduce the possibility of short circuit caused by the core being inserted into the bending portion 270 during bending. Compared with the case where the electrode tab 200 has insulating layers of the same height on both sides, the way the insulating layer on one side of the electrode tab 200 extends beyond the insulating layer on the other side in this embodiment can also reduce the bending difficulty of the bending portion 270.

[0088] Specifically, such as Figure 5 As shown, the electrode assembly 700 includes a battery cell body and a tab 200. The tab 200 includes a first connecting section 250 and a second connecting section 260. The first connecting section 250 is connected to the battery cell body, and the second connecting section 260 is electrically connected to the electrode post. A bending portion 270 is connected between the first connecting section 250 and the second connecting section 260, thereby enabling the first connecting section 250 and the second connecting section 260 to be bent and connected. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 is located in the bending portion 270.

[0089] This application also proposes a battery pack, including the electrode sheets of any of the above embodiments, or the battery cells of any of the above embodiments.

[0090] In the embodiments of this application, since the battery pack includes either the electrode sheets of any of the above embodiments or the battery cells of any of the above embodiments, the electrode sheets need to be bent when assembled into the battery cells to connect with the terminals. The portion of the second insulating layer 400 that extends beyond the first insulating layer 300 can improve the insulation performance of the tab 200, thereby reducing the possibility of a short circuit when the tab 200 is bent and inserted into the battery cell. Compared to the case where the insulating layers on both sides of the tab 200 are of the same height, the way in the embodiments of this application where the insulating layer on one side of the tab 200 extends beyond the insulating layer on the other side can also reduce the bending difficulty of the tab 200, reduce the space occupied on the top of the battery cell, and improve the energy density of the battery cell.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. 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.

[0092] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. An electrode sheet, characterized in that, include: A current collector (100) having a first direction (X) and a second direction (Y) that are perpendicular to each other; A tab (200) protrudes from the current collector (100) along the first direction (X), and the tab (200) has a first surface (210) and a second surface (220) disposed opposite to each other along the second direction (Y); A first insulating layer (300) covers a portion of the first surface (210); A second insulating layer (400) covers at least a portion of the second surface (220), and one end of the second insulating layer (400) opposite to the current collector (100) extends beyond one end of the first insulating layer (300) opposite to the current collector (100).

2. The electrode sheet according to claim 1, characterized in that, The current collector (100) has a first side (110) and a second side (120) opposite each other along the second direction (Y), the first side (110) corresponding to the first surface (210); The first insulating layer (300) includes a first sub-insulating portion (310) and a second sub-insulating portion (320) connected to each other. The first sub-insulating portion (310) covers the edge portion of the first side (110) near the tab (200), and the second sub-insulating portion (320) covers a portion of the first surface (210). The second insulating layer (400) includes a third sub-insulating portion (410) and a fourth sub-insulating portion (420) connected to each other, the third sub-insulating portion (410) covering the edge portion of the second side (120) near the tab (200), and the fourth sub-insulating portion (420) covering at least a portion of the second surface (220); Along the first direction (X), the end of the fourth sub-insulator (420) away from the current collector (100) extends beyond the end of the second sub-insulator (320) away from the current collector (100).

3. The electrode sheet according to claim 2, characterized in that, The current collector (100) also has a third direction (Z) perpendicular to the first direction (X) and the second direction (Y). The portion of the fourth sub-insulating portion (420) that extends beyond the second sub-insulating portion (320) is provided as a protrusion (421), and the protrusion (421) is provided with a groove (440) extending along the third direction (Z).

4. The electrode sheet according to claim 3, characterized in that, At least one of the following conditions must be met: A. The number of the grooves (440) is multiple, and the multiple grooves (440) are arranged at intervals along the first direction (X); B. The groove (440) extends through the protrusion (421) along the second direction (Y); C. The groove (440) penetrates the protrusion (421) along the third direction (Z).

5. The electrode sheet according to claim 2, characterized in that, Along the first direction (X), the fourth sub-insulating portion (420) has a continuously extending structure.

6. The electrode sheet according to any one of claims 1 to 5, characterized in that, The second insulating layer (400) extends 1 mm to 20 mm beyond the first insulating layer (300) along the first direction (X).

7. A battery cell, characterized in that, The device includes a housing and an electrode assembly (700), the housing having a receiving cavity (610), the electrode assembly (700) being disposed in the receiving cavity (610), the electrode assembly (700) being formed by stacking or winding electrode sheets; at least a portion of the electrode sheets in the electrode assembly (700) are electrode sheets as described in any one of claims 1 to 6.

8. The battery cell according to claim 7, characterized in that, The battery cell includes at least two electrode assemblies (700) arranged side by side. Along the side-by-side direction of the at least two electrode assemblies (700), the housing includes two opposing housing sidewalls (601). The electrode assembly closer to the housing sidewall (601) is the first electrode assembly. The height direction of the battery cell is the first direction (X). The first electrode assembly has a central axis (C) extending along the first direction (X). The electrode in the first electrode assembly located on the side of the central axis (C) closer to the housing sidewall (601) adopts the electrode as described in any one of claims 1 to 6.

9. The battery cell according to claim 8, characterized in that, The electrode located on the side of the central axis (C) near the shell sidewall (601) is designated as the target electrode, the electrode tab provided on the target electrode is designated as the target electrode tab, and the surface of the target electrode tab opposite to the shell sidewall (601) is provided with the second insulating layer (400).

10. The battery cell according to any one of claims 7 to 9, characterized in that, The electrode assembly (700) includes a cell body and a tab (200). The tab (200) includes a first connecting segment (250), a second connecting segment (260), and a bending portion (270). The first connecting segment (250) and the second connecting segment (260) are bent together to form a bending portion (270) between the first connecting segment (250) and the second connecting segment (260). The first connecting segment (250) is used to connect to the cell body, and the second connecting segment (260) is used to connect to the terminal post. The portion of the second insulating layer (400) that extends beyond the first insulating layer (300) is located in the bending portion (270).

11. A battery pack, characterized in that, It includes the electrode sheet as described in any one of claims 1 to 6, or the cell as described in any one of claims 7 to 10.

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