Pole group, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, in particular to a pole group, a battery cell and a battery pack. The pole group comprises a first pole piece, a second pole piece and a separator; the first pole pieces and the second pole pieces are alternately stacked, the separators are clamped between the adjacent first pole pieces and second pole pieces, the separators protrude out of the edges of the first pole pieces in the first direction and are hot-pressed with the first pole pieces to form edge sealing parts, and the size A of the edge sealing parts in the first direction is larger than or equal to 1.5 mm and smaller than or equal to 3.5 mm. According to the invention, the contact area between the electrolyte and the separator is increased, and the electrolyte retention capacity and the infiltration efficiency of the first pole piece and the second pole piece in the cell preparation process are improved, so that more electrolyte can be retained in the cell, and the battery pack has relatively high cycle performance; meanwhile, the larger edge sealing distance enables the battery cells to play a certain buffering role in the vibration process, and the overall safety performance of the battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a pole group, a battery cell, and a battery pack. Background Art

[0002] Lithium-ion batteries have become the most widely used secondary batteries due to their advantages such as high energy density, good cycling performance, high working voltage, and no memory effect. As power batteries, they are widely used in electric vehicles and energy storage fields. The requirements for the performance and safety of lithium-ion batteries are increasing day by day.

[0003] The existing battery stacking processes mainly include winding and Z-stacking. As Figure 1 shown, Z-stacking has a higher space utilization rate and is formed by sequentially stacking the electrode sheets 2. This also makes the Z-stacking occupy less volume inside the housing under the same volume, so that more electrolyte can be injected. Since the separator 1 is compressible, the internal space of the battery cell can be measured only by determining the distance from the electrode sheet 2 to the inner wall of the housing in the conventional battery cell design. This also makes the edge sealing of the battery cell designed according to the smallest possible size. As Figure 2 shown, the whole separator 1 wraps the electrode sheet 2 through Z-shaped folding, so that there are U-shaped corners at the edge sealing positions of two adjacent separators 1 after folding. In the existing blade batteries, due to their long size, when injecting electrolyte into the housing from the injection port, the flow rate of the electrolyte inside the housing is slow, and there is a certain distance between the pole group and the inner wall of the housing, resulting in a long time for the electrolyte to flow into the electrode sheet. During the negative pressure cycle process, the electrolyte will be pumped out again, resulting in a small amount of electrolyte retained in the battery cell, thus affecting the wetting efficiency of the electrode sheet. The unstable SEI film (solid electrolyte interface film) will decompose and regenerate repeatedly during the cycle, consuming reversible lithium sources and electrolytes, resulting in cycle failure. Therefore, under the conditions of ensuring sufficient electrolyte injection and full wetting, increasing the retention amount of the electrolyte can improve the cycle performance. Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide a pole group, a battery cell, and a battery pack to solve the problems of low liquid retention amount of the existing pole group and low wetting efficiency of the electrode sheet.

[0005] The first aspect of the present invention provides a pole group, wherein the pole group includes a first electrode sheet, a second electrode sheet, and a separator; The first electrode tab and the second electrode tab are stacked alternately with each other, the separator is sandwiched between the adjacent first electrode tab and the second electrode tab, the separator protrudes from the edge of the first electrode tab in the first direction and is thermocompressed with the first electrode tab to form a sealing edge portion, the size of the sealing edge portion in the first direction is A, and 1.5 mm ≤ A ≤ 3.5 mm; the separator is a cut single-piece structure, and each separator is attached to the surface of the first electrode tab and / or the second electrode tab. In the above technical solution, further, the first electrode tab is a negative electrode tab. In any of the above technical solutions, further, the area of the first electrode tab is larger than the area of the second electrode tab.

[0006] In any of the above technical solutions, further, the first electrode tab has a protruding first pole ear, and the first pole ear and the sealing edge portion are arranged on different side walls of the electrode group; The second electrode tab has a protruding second pole ear, and the second pole ear and the sealing edge portion are arranged on different side walls of the electrode group. In any of the above technical solutions, further, the protruding direction of the first pole ear and / or the protruding direction of the second pole ear are perpendicular to the first direction. In any of the above technical solutions, further, the separators are arranged on both sides of the electrode group in its thickness direction.

[0007] In any of the above technical solutions, further, the first electrode tab, the second electrode tab and / or the separator are formed into a rectangular sheet structure. In any of the above technical solutions, further, the areas of the first electrode tab and the second electrode tab are both smaller than the area of the separator, and the first electrode tab and the second electrode tab are arranged at the middle positions of the separator.

[0008] A second aspect of the present invention provides an electric core, including the electrode group according to any of the above technical solutions.

[0009] A third aspect of the present invention provides a battery pack, including the electric core according to the above technical solution.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: The electrode assembly of the present invention includes a first electrode plate, a second electrode plate, and a separator; the first electrode plate and the second electrode plate are alternately stacked on top of each other, the separator is sandwiched between adjacent first and second electrode plates, the separator protrudes beyond the edge of the first electrode plate in the first direction and is thermocompressed with the first electrode plate to form a sealing edge portion, the size of the sealing edge portion in the first direction is A, 1.5 mm ≤ A ≤ 3.5 mm, which increases the size of the sealing edge compared to the conventional electrode assembly, the size of the separator is larger, doubling the proportion of the electrolyte directly immersed in the electrode plate and increasing the contact area between the electrolyte and the separator, and the separator is a cut single-piece structure, each separator is attached to the surface of the first electrode plate and / or the second electrode plate, so different from an electrode assembly formed by folding a whole diaphragm in a Z-shape and wrapping the positive and negative electrode plates, each separator in this application is independent, there is no U-shaped fold angle, the electrolyte can contact the separator earlier and more, and adhere to the surface of the separator, and flow along the separator into the first electrode plate and the second electrode plate, enabling the electrode plates between each layer of separators to directly contact the electrolyte, thus improving the liquid retention amount of the electrolyte and the infiltration efficiency of the first electrode plate and the second electrode plate during the preparation of the battery cell, so that more electrolyte can be retained inside the battery cell, improving the charge and discharge performance and capacity of the battery cell, and further enabling the battery pack to have higher cycle performance. At the same time, the larger sealing edge distance plays a certain buffering role during the vibration of the battery cell, improving the overall safety performance of the battery pack.

[0011] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0013] Figure 1 is a schematic diagram of the lamination process in the prior art; Figure 2 is a schematic diagram of the structure of the electrode assembly in the prior art; Figure 3 is a schematic diagram of the structure of the electrode assembly provided by the embodiment of the present invention; Figure 4 is a schematic diagram of the structure of the electrode assembly provided by the embodiment of the present invention from another perspective; Figure 5 is a comparison diagram of the liquid loss detection between the electrode assembly provided by the embodiment of the present invention and the electrode assembly in the prior art; Figure 6The figure shows a comparison of the cell stack provided by the embodiments of the present invention with that of the prior art under normal temperature cycling test. Figure 7 The figure shows a comparison of the interfaces of the negative electrode sheets after vibration disassembly of the edge-sealing parts of different sizes A in the cell stack of the embodiments of the present invention.

[0014] Icons: 10 - First electrode sheet; 11 - First tab; 20 - Second electrode sheet; 21 - Second tab; 30 - Separator; 31 - Edge-sealing part; D1 - First direction; 1 - Diaphragm; 2 - Electrode sheet; 3 - U-shaped fold angle. Detailed embodiments

[0015] The following detailed embodiments are provided to assist the reader in obtaining a comprehensive understanding of the methods, devices, and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein. Rather, changes that will be apparent after understanding the disclosure of the present application may be made, except for operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for the sake of clarity and conciseness.

[0016] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many possible ways of implementing the methods, devices, and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0017] Throughout the specification, when an element (such as a layer, region, or substrate) is described as "on" another element, "connected to" another element, "bonded to" another element, "above" another element, or "covering" another element, it may be directly "on", "connected to", "bonded to", "above", or "covering" another element, or there may be one or more other elements therebetween. In contrast, when an element is described as "directly on", "directly connected to", "directly bonded to", "directly above", or "directly covering" another element, there may be no other elements therebetween.

[0018] As used herein, the term "and / or" includes any one of the listed related items and any combination of any two or more of them.

[0019] Although terms such as "first", "second", and "third" may be used herein to describe various components, elements, regions, layers, or sections, these components, elements, regions, layers, or sections are not limited by these terms. Rather, these terms are only used to distinguish one component, element, region, layer, or section from another. Thus, a first component, element, region, layer, or section referred to in the examples described herein may also be referred to as a second component, element, region, layer, or section without departing from the teachings of the examples.

[0020] For ease of description, spatial relationship terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another as shown in the figures. Such spatial relationship terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "above" or "upper" relative to another element will then be "below" or "lower" relative to the other element. Thus, the term "above" includes both the orientation of "above" and "below" depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or at other orientations), and the spatial relationship terms used herein will be interpreted accordingly.

[0021] The terms used herein are for the purpose of describing various examples only and are not intended to limit the disclosure. Unless the context clearly dictates otherwise, the singular forms are also intended to include the plural forms. The terms "comprises", "comprising", and "having" list the stated features, quantities, operations, components, elements, and / or combinations thereof that exist, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0022] Due to manufacturing techniques and / or tolerances, variations in the shapes shown in the figures may occur. Thus, the examples described herein are not limited to the specific shapes shown in the figures, but include changes in shape that occur during manufacturing.

[0023] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have a variety of configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0024] According to a first aspect of the present invention, a pole group is provided, which includes a first pole piece 10, a second pole piece 20, and a separator 30.

[0025] In the following, the specific structures of the above components of the electrode group according to this embodiment will be described.

[0026] In this embodiment, as Figure 3 shown, the first electrode tab 10 and the second electrode tab 20 are alternately stacked on top of each other. Both the first electrode tab 10 and the second electrode tab 20 are formed in a sheet-like structure. One of the first electrode tab 10 and the second electrode tab 20 is a positive electrode tab, and the other is a negative electrode tab; the separator 30 is sandwiched between the adjacent first electrode tab 10 and second electrode tab 20. The separator 30 can be a diaphragm, and the diaphragm is made of PE or PP material, which can isolate the positive electrode tab and the negative electrode tab and prevent electrons from directly passing through, while allowing ions in the electrolyte to freely pass between the positive and negative electrodes, ensuring the safety performance of the electrode group.

[0027] In the electrode group structure of this embodiment, the U-shaped fold on the diaphragm is cancelled compared with the traditional electrode group. Specifically, the separator 30 is a cut single-piece structure, and each piece of separator 30 adheres to the surface of the first electrode tab 10 and / or the second electrode tab 20. Each layer of separator 30 is independently and alternately inserted between the first electrode tab 10 and the second electrode tab in parallel, so that there is no Figure 1 and Figure 2 U-shaped fold 3 shown in. Thus, different from the electrode group formed by folding and wrapping the positive and negative electrode tabs in a Z-shape with a whole diaphragm, each separator 30 in this application is independent and there is no U-shaped fold. The electrolyte can contact the separator 30 earlier and more, and adhere to the surface of the separator 30, and flow into the first electrode tab 10 and the second electrode tab 20 along the separator 30, so that the electrode tabs between each layer of separator 30 can directly contact the electrolyte. In this way, the liquid retention amount of the electrolyte and the infiltration efficiency of the first electrode tab 10 and the second electrode tab 20 during the preparation of the battery cell are improved, so that more electrolyte can be retained inside the electrode group, and the electrode group has a better wetting effect.

[0028] In this embodiment, as Figure 3 and Figure 4 shown, the first electrode tab 10, the second electrode tab 20 and / or the separator 30 are formed in a rectangular sheet-like structure, so that at least one first electrode tab 10, at least one second electrode tab 20 and a plurality of separators 30 are stacked to form an electrode group with a rectangular body structure, thus meeting the assembly requirements of blade-type battery cells or square battery cells and ensuring the battery cell capacity.

[0029] It should be noted that the more layers the first electrode tab 10 and the second electrode tab 20 are stacked, the thicker the thickness dimension of the electrode group. Therefore, the length direction and width direction of the electrode group are the length direction and width direction of the electrode tabs.

[0030] For the structure of the electrode group in the prior art, refer to Figure 2As shown, the separator 1 covers one end of the electrode plate 2, and the edge sealing distance is usually about 1 mm. In this embodiment, as Figure 3 and Figure 4 shown, the part of the separator 30 protruding from the edge of the first electrode plate 10 in the first direction D1 is hot-pressed with the first electrode plate 10 to form a sealing edge portion 31. The size of the sealing edge portion 31 in the first direction D1 is A, and 1.5 mm ≤ A ≤ 3.5 mm. In this way, the edge sealing distance is increased, and since there is no U-shaped fold angle between two adjacent separators 30, the contact area between the separator 30 and the electrolyte is increased, which can most effectively directly increase the ionic conductivity, enabling the electrolyte to contact and adhere to the surface of the separator 30 earlier and more, and flow into the first electrode plate 10 and the second electrode plate 20 along the separator 30. In this way, the liquid retention amount of the electrolyte during the preparation of the battery cell and the infiltration efficiency of the first electrode plate 10 and the second electrode plate 20 are improved, thereby improving the liquid retention amount of the electrode group, making the electrode group have a better wetting effect, and further enabling the battery cell to have a higher retention rate during long-term cycling. At the same time, the larger edge sealing distance plays a certain buffering role during the vibration of the battery cell, improving the overall safety performance of the battery pack.

[0031] Next, the liquid retention test and vibration test were carried out on the electrode groups with different sizes A to verify the reliability of the defined range of 1.5 mm ≤ A ≤ 3.5 mm. The test results are shown in Table 1, where the test conditions for the vibration test refer to the standard of GB 31467.3-7.1.2. To magnify the differences, the vibration was carried out twice, and after the vibration, the fully charged battery cell was disassembled to check the interface condition of the negative electrode plate.

[0032] Table 1

[0033] It should be noted that in Table 1, the result of OK indicates that the detection is qualified, and the result of NG indicates the existence of safety risks. Referring to Table 1, it can be seen that in Examples 1 to 8, the parameter of A is between 1.5 mm and 3.5 mm. The liquid retention amount of the electrode group is improved, making the electrode group have a better wetting effect, so as to achieve a higher retention rate of the battery cell during long-term cycling, and it can also prevent the separator 30 from pressing and damaging the positive and negative electrode plates during vibration due to the too long size of the sealing edge portion 31 and the internal electrode group from moving due to the too large internal space gap caused by the too short separator 30, resulting in a series of safety problems.

[0034] In addition, the vibration results of Example 3, Comparative Example 2, and Comparative Example 4 are as Figure 7As shown, there is slight material loss in the overhang area of the negative electrode sheet (i.e., the non-overlapping area between the first electrode sheet 10 and the second electrode sheet 20) after the electrode group with A = 1 mm is disassembled. The electrode group with A = 5 mm has a greater amount of separator 30 wrapped by mylar per unit volume, resulting in excessive extrusion of the separator 30. At the same time, after vibration testing, there is obvious material loss in the negative electrode sheet. There is no abnormality in the negative electrode sheet after the electrode group with A = 2 mm is disassembled.

[0035] When the sizes of the positive and negative electrode sheets are the same, in this application, the edge sealing distance is increased by two times or more on one side compared with the traditional edge sealing distance. Twenty traditional stacked cells are taken as the comparative example before improvement and the improved cells of this application with an increased edge sealing distance respectively. According to the same vacuum degree, pressure holding time, and number of positive and negative pressure circulation cycles, the same electrolyte is injected to conduct a comparison of the liquid loss amount detection. The test results are as Figure 5 shown. The liquid loss amount of the improved cells is lower, only 32% of that of the traditional cells. Therefore, it is proved that changing the Z-shaped diaphragm stacking method to the stacking method of the separator 30 arranged in parallel and independently and increasing the edge sealing distance to 1.5 mm - 3.5 mm in this embodiment can effectively increase the liquid retention amount of the electrode group, making the electrode group have a better wetting effect.

[0036] Furthermore, under the condition that other conditions are the same, with the structure of the separator 30 and the edge sealing distance as variables, the traditional stacked cells are used as the comparative example before improvement and the improved cells of this application with an increased edge sealing distance are subjected to a normal temperature cycle test. The test temperature is 25°C. The test results are as Figure 6 shown. After 200 cycles, the normal temperature cycle capacity retention rate of the improved cells can be 1% higher than that of the traditional cells before improvement. This is mainly because the improved cells in this embodiment can retain more electrolyte inside, ensuring that the SEI film can be repeatedly decomposed and regenerated during the cycle process, thus maintaining a higher cycle performance.

[0037] In the preferred embodiment, as Figure 3 and Figure 4 shown, the edge sealing part 31 is arranged at both ends of the separator 30 in the first direction D1, so that the edge sealing distances on both sides of the electrode group are increased, thereby maximizing the liquid retention amount of the electrode group.

[0038] In this embodiment, as Figure 3 shown, the first electrode sheet 10 is a negative electrode sheet. Furthermore, in this embodiment, as Figure 3 and Figure 4 shown, the area of the first electrode sheet 10 is larger than that of the second electrode sheet 20.

[0039] In the preferred embodiment, as Figure 3 and Figure 4As shown, the area of the first electrode tab 10 and the area of the second electrode tab 20 are both smaller than the area of the separator 30. The first electrode tab 10 and the second electrode tab 20 are arranged at the middle position of the separator 30, so as to ensure that the separator 30 can effectively separate the first electrode tab 10 and the second electrode tab 20.

[0040] Further, in this embodiment, as Figure 4 shown, the first electrode tab 10 has a protruding first tab 11. The first tab 11 and the edge-sealing part 31 are arranged on different side walls of the electrode assembly. When the first electrode tab 10 is a negative electrode tab, the first tab 11 is the negative tab, and the negative tab is connected to the negative terminal of the battery cell; the second electrode tab 20 has a protruding second tab 21. The second tab 21 and the edge-sealing part 31 are arranged on different side walls of the electrode assembly. When the second electrode tab 20 is a positive electrode tab, the second tab 21 is the positive tab, and the positive tab is connected to the positive terminal of the battery cell. In this way, the edge-sealing part 31 is arranged on the side wall of the electrode assembly without tabs. It should be noted that a sealing structure may also be arranged on the side of the electrode assembly where the first tab 11 and / or the second tab 21 are arranged, but the size of this sealing structure is not clearly controlled.

[0041] Specifically, the positive tab and the negative tab can protrude along the length direction or the width direction of the electrode assembly. For example, when the positive tab and the negative tab protrude along the length direction of the electrode assembly, the edge-sealing part 31 is arranged on both sides in the width direction of the electrode assembly; for example, when the positive tab and the negative tab protrude along the width direction of the electrode assembly, the edge-sealing part 31 is arranged on both sides in the length direction of the electrode assembly. In this embodiment, the first direction D1 can be the length direction or the width direction of the electrode assembly.

[0042] In an alternative embodiment, when the battery cell is a blade battery cell, the first tab 11 and the second tab 21 protrude away from each other. In other alternative embodiments, the protruding directions of the first tab 11 and the second tab 21 are the same. Furthermore, as Figure 4 shown, the protruding direction of the first tab 11 and / or the protruding direction of the second tab 21 are perpendicular to the first direction D1.

[0043] In this embodiment, separators 30 are arranged on both sides of the electrode assembly in its thickness direction. The separators 30 have sufficient mechanical strength to resist external extrusion and tensile forces to a first degree, so as to ensure the integrity of the electrode assembly structure, ensure the safe and stable operation of the battery cell, and extend the service life of the battery pack.

[0044] A pole group provided according to the present invention includes a first pole piece, a second pole piece, and a separator; the first pole piece and the second pole piece are stacked alternately with each other, the separator is clamped between adjacent first and second pole pieces, the separator protrudes beyond the edge of the first pole piece in the first direction and is thermocompressed with the first pole piece to form a sealing edge portion, the size of the sealing edge portion in the first direction is A, 1.5 mm ≤ A ≤ 3.5 mm, which increases the size of the sealing edge compared to the conventional pole group, the size of the separator is larger, doubling the proportion of the electrolyte directly immersed in the pole piece and increasing the contact area between the electrolyte and the separator at the same time, and the separator is a cut single-piece structure, each piece of the separator fits on the surface of the first pole piece and / or the second pole piece. Thus, different from a pole group formed by folding and wrapping the positive and negative pole pieces with a whole diaphragm in a Z-shape, each separator in this application is independent and there is no U-shaped fold angle. The electrolyte can contact the separator earlier and more, and adhere to the surface of the separator, and flow along the separator into the first pole piece and the second pole piece, so that the pole pieces between each layer of separators can directly contact the electrolyte. In this way, the liquid retention amount of the electrolyte and the infiltration efficiency of the first pole piece and the second pole piece are improved during the preparation process of the battery cell, so that more electrolyte can be retained inside the pole group, and the pole group has a better wetting effect.

[0045] A battery cell provided according to the present invention has the above-described pole group disposed inside. The infiltration efficiency of the first pole piece and the second pole piece in the pole group is improved, so that more electrolyte can be retained inside the battery cell, ensuring that the battery cell can maintain a high cycle performance, improving the charge and discharge performance and capacity of the battery cell, and having higher safety performance at the same time.

[0046] A battery pack provided according to the present invention includes the battery cell provided in the above embodiment. A plurality of battery cells are connected in series and / or in parallel to form a battery module, and the battery module is assembled in the housing of the battery pack, improving the cycle ability of the battery pack, extending the service life of the battery pack, meeting the user's usage requirements for the battery pack. At the same time, the larger sealing edge distance enables the battery cell to play a certain buffering role during vibration, improving the overall safety performance of the battery pack.

[0047] Finally, it should be noted that the above-described embodiments are only specific implementation manners of the present application, used to illustrate the technical solutions of the present application, rather than limiting it. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present application can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A plate group, characterized in that, The electrode group includes a first electrode tab, a second electrode tab and a separator; The first electrode tab and the second electrode tab are alternately stacked with each other. The separator is clamped between the adjacent first electrode tab and the second electrode tab. The separator protrudes from the edge of the first electrode tab in the first direction and is thermocompressed with the first electrode tab to form a sealing edge portion. The size of the sealing edge portion in the first direction is A, and 1.5 mm ≤ A ≤ 3.5 mm. The separator is a cut single-piece structure, and each separator is attached to the surface of the first electrode tab and / or the second electrode tab.

2. The electrode group according to claim 1, wherein The first electrode tab is a negative electrode tab.

3. The electrode group according to claim 1, characterized in that, The area of the first electrode tab is larger than the area of the second electrode tab.

4. The electrode group according to claim 1, wherein The first electrode tab has a protruding first tab, and the first tab and the sealing edge portion are arranged on different side walls of the electrode group; The second electrode tab has a protruding second tab, and the second tab and the sealing edge portion are arranged on different side walls of the electrode group.

5. The electrode group according to claim 4, characterized in that, The protruding direction of the first tab and / or the protruding direction of the second tab is perpendicular to the first direction.

6. The electrode group according to claim 1, wherein The separators are arranged on both sides of the electrode group in its thickness direction.

7. The electrode group according to claim 1, wherein The first electrode tab, the second electrode tab and / or the separator form a rectangular sheet structure.

8. The electrode group according to claim 1, characterized in that, The areas of the first electrode tab and the second electrode tab are both smaller than the area of the separator, and the first electrode tab and the second electrode tab are arranged at the middle position of the separator.

9. A battery cell, characterized in that, An electrode group according to any one of claims 1 to 8.

10. A battery pack, characterized in that, A battery cell including the electrode group according to claim 9.

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