Battery cell pole group and battery cell
Patent Information
- Application Number
- CN202510310679.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-06-13
AI Technical Summary
The existing battery cell electrode sets are prone to problems with the electrode holder after the electrode height increases, which affects the safety of foil welding, and even has the risk of safety accidents caused by inserting the electrode set into the electrode set.
A battery cell pole set is designed, and the pole ear includes a plurality of welding areas and grooves, the grooves are located in the non-welded areas of the pole ear, and the pole ear has a weight reduction gap to reduce the weight of the pole ear and prevent bedding.
By opening grooves and weight reduction gaps in the non-welded area of the electrode, the weight of the electrode is reduced, preventing the electrode from staying, and improving the safety and quality of the battery cell.
Smart Images
Figure CN120149761A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of energy storage devices, and particularly to an electrode assembly for a battery cell and a battery cell. Background Art
[0002] The electrode assembly of a battery cell is a core component of the battery cell, and the quality of the electrode assembly directly affects the quality and performance of the battery cell. In the prior art, in order to improve the mass energy density and safety performance of the battery cell, some battery cells no longer provide connecting tabs for the positive and negative electrodes, but instead appropriately increase the height of the tabs and directly connect the tabs to the terminal posts, which requires an increase in the height of the tabs. After the electrode roll is cut by laser die-cutting to obtain the electrode foil, when transferring the electrode foil, a suction or support member is used to adsorb or support the area of the electrode body of the electrode foil, and the tab portion does not receive a support force. Once the tab height increases, the problem of tab collapse is likely to occur, which not only affects the welding of the foil, but also poses a risk of safety accidents due to the insertion of the tab into the electrode assembly. Summary of the Invention
[0003] An object of the present invention is to provide an electrode assembly for a battery cell, which helps to avoid the problem of tab collapse and ensure the safety of the battery cell.
[0004] To achieve this object, the present invention adopts the following technical solutions:
[0005] Provide an electrode assembly for a battery cell, including multiple layers of electrodes. The electrode includes an electrode body and a tab. The tab includes A welding areas, and the A welding areas are sequentially spaced along a first direction. A is a positive integer greater than 1. B grooves are provided between two adjacent welding areas. B is a positive integer. The tab has a first side and a second side that are oppositely arranged along a second direction. The grooves are located on the first side. The second side is connected to the electrode body. The second direction is perpendicular to the first direction. A first weight-reducing notch is provided at the position where the first side is not provided with the groove. The depth of the first weight-reducing notch is less than the depth of the groove.
[0006] Optionally, A is 2, B is 1. Along the second direction, the depth L1 of the groove and the height L2 of the tab satisfy 0.4 ≤ L1 / L2 ≤ 0.6;
[0007] And / or, A is 2, B is 1. Along the first direction, the width L3 of the groove and the width L4 of the tab satisfy 0.1 ≤ L3 / L4 ≤ 0.3;
[0008] And / or, the height L2 of the tab and the width L4 of the tab satisfy 2 ≤ L4 / L2 ≤ 3.
[0009] Optionally, the shortest distance L5 between the side wall of the groove and the welding area ranges from 2 mm to 5 mm;
[0010] And / or, the shortest distance L6 between the welding area and the edge of the first side ranges from 2 mm to 5 mm;
[0011] And / or, the shortest distance L7 between the welding area and one side of the tab along the first direction ranges from 2 mm to 5 mm.
[0012] Optionally, B is greater than 1, and a plurality of the grooves between two adjacent welding areas are evenly spaced.
[0013] Optionally, A is greater than 2, B is 1, the groove is provided between any two adjacent welding areas, and a plurality of the grooves are evenly spaced, and / or, the widths of a plurality of the grooves are the same, and / or, the depths of a plurality of the grooves are the same.
[0014] Optionally, the groove is a polygonal groove or a semi-circular groove.
[0015] Optionally, a second weight-reducing notch is provided on the side wall and / or the bottom of the groove, and the depth of the second weight-reducing notch is less than the depth of the groove;
[0016] And / or, the tab has a third side and a fourth side oppositely arranged along the first direction, and the third side has a third weight-reducing notch;
[0017] And / or, the fourth side has a fourth weight-reducing notch.
[0018] Optionally, a plurality of the first weight-reducing notches are provided;
[0019] And / or, a plurality of the second weight-reducing notches are provided;
[0020] And / or, a plurality of the third weight-reducing notches are provided;
[0021] And / or, a plurality of the fourth weight-reducing notches are provided.
[0022] Optionally, the depth a of the first weight-reducing notch ranges from 1 mm to 2 mm;
[0023] And / or, the depth b of the second weight-reducing notch ranges from 1 mm to 2 mm;
[0024] And / or, the depth c of the third weight-reducing notch ranges from 1 mm to 2 mm;
[0025] And / or, the depth d of the fourth weight reduction notch ranges from 1 mm ≤ d ≤ 2 mm.
[0026] Another object of the present invention is to provide an electric core, which helps to avoid the problem of tab sagging and ensure the safety of the electric core.
[0027] To achieve this object, the present invention adopts the following technical solutions:
[0028] Provide an electric core, including a housing and the above-mentioned electric core electrode group, and the electric core electrode group is located inside the housing.
[0029] The beneficial effects of the present invention:
[0030] The present invention provides an electric core electrode group, including multiple layers of electrode sheets. The electrode sheet includes an electrode sheet body and tabs. The tabs include A welding areas, and the A welding areas are sequentially arranged at intervals along the first direction. A is a positive integer greater than 1. B grooves are provided between two adjacent welding areas. B is a positive integer. The tabs have a first side and a second side arranged opposite to each other along the second direction. The grooves are located on the first side. The second side is connected to the electrode sheet body. The second direction is perpendicular to the first direction. A first weight reduction notch is provided at the non-grooved part of the first side. The depth of the first weight reduction notch is less than the depth of the groove. By providing grooves in the non-welding area of the tabs, the weight of the tabs can be reduced without affecting the welding of the tabs, thereby reducing the force on the tabs during the transfer of the electrode sheet foil, and preventing the tabs from sagging away from the electrode sheet. Moreover, the electric core electrode group further reduces the weight of the tabs by providing a first weight reduction notch on the first side, thereby reducing the force on the tabs away from the electrode sheet and further preventing the tab foil from sagging. Therefore, the electric core electrode group helps to improve the use safety of the electric core.
[0031] The present invention also provides an electric core, including a housing and the above-mentioned electric core electrode group, and the electric core electrode group is located inside the housing. This electric core helps to avoid the problem of tab sagging and ensure the safety of the electric core. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 is a schematic structural diagram of the electrode sheet provided by an embodiment of the present invention;
[0033] Figure 2 is Figure 1 the enlarged view of A in
[0034] Figure 3 is a schematic structural diagram of the electric core electrode group provided by an embodiment of the present invention.
[0035] In the figure:
[0036] 1. Electrode sheet body; 2. Tab; 21. Welding area; 22. Groove; 221. Second weight reduction notch; 23. First side; 231. First weight reduction notch; 24. Second side; 25. Third side; 251. Third weight reduction notch; 26. Fourth side; 261. Fourth weight reduction notch. Detailed implementation mode
[0037] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and implementation modes. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only parts related to the present invention are shown in the drawings, rather than all of them.
[0038] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.
[0039] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above", and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below", and "under" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the horizontal height of the first feature is lower than that of the second feature.
[0040] The electrode group of the battery cell is the core component of the battery cell, and the quality of the electrode group of the battery cell directly affects the quality and performance of the battery cell. In the prior art, in order to improve the mass energy density and safety performance of the battery cell, some battery cells no longer set the connection sheets for the positive and negative electrodes, but appropriately increase the height of the tabs and directly connect the tabs to the electrode posts, which requires increasing the height of the tabs. After the electrode roll is laser die-cut to obtain the electrode sheet foil, when transferring the electrode sheet foil, the adsorption or support of the area of the electrode sheet body of the electrode sheet foil will be carried out by using the adsorbent or support member, while the tab part cannot obtain the support force. Once the tab height increases, the problem of tab sagging is likely to occur, which not only affects the foil welding, but also there is a risk of the tab inserting into the electrode group and causing a safety accident.
[0041] To solve the above problems, this embodiment provides a battery cell electrode group, which can help avoid the problem of the tab 2 sagging and ensure the safety of the battery cell.
[0042] As Figures 1 - 3 shown, the battery cell electrode group of this embodiment includes multiple layers of electrode sheets, and the electrode sheet includes an electrode sheet body 1 and a tab 2. Figure 1 In Figure 1 , the ab direction is the first direction, and the cd direction is the second direction. The tab 2 includes A welding areas 21, and the A welding areas 21 are arranged at intervals in the first direction. A is a positive integer greater than 1. There are B grooves 22 opened between two adjacent welding areas 21. B is a positive integer. The tab 2 has a first side 23 and a second side 24 arranged oppositely in the second direction. The groove 22 is located on the first side 23. The second side 24 is connected to the electrode sheet body 1. The second direction is perpendicular to the first direction. A first weight reduction notch 231 is opened at the place where the first side 23 is not provided with a groove 22, and the depth of the first weight reduction notch 231 is less than the depth of the groove 22.
[0043] By opening the groove 22 in the non-welding area 21 of the tab 2, this battery cell electrode group can reduce the weight of the tab 2 without affecting the welding of the tab 2, thereby reducing the force on the tab 2 during the transfer of the electrode sheet foil and preventing the tab 2 from sagging away from the electrode sheet. Moreover, this battery cell electrode group further reduces the weight of the tab 2 by opening the first weight reduction notch 231 on the first side 23, thereby reducing the force on the tab 2 away from the electrode sheet and further preventing the tab 2 foil from sagging. Therefore, this battery cell electrode group helps to improve the use safety of the battery cell.
[0044] It should be noted that since there is a weight reduction notch on the edge of the tab 2, for the following mentioned dimensional data, if there is a weight reduction notch at the starting point or the ending point of the measurement, the midline of the weight reduction notch is used as the measurement reference, and the midline of the weight reduction notch is the midline between the deepest part and the highest part of the weight reduction notch.
[0045] Optionally, in this embodiment, the value of A is 2, and the value of B is 1, that is, as Figure 2As shown, when the tab 2 has two welding areas 21 and only one groove 22 is provided between the two welding areas 21, along the second direction, the depth L1 of the groove 22 and the height L2 of the tab 2 satisfy 0.4 ≤ L1 / L2 ≤ 0.6. When the ratio of the depth L1 of the groove 22 to the height L2 of the tab 2 is less than 0.4, that is, the groove 22 is too shallow, the weight of the tab 2 is still relatively large, and when the tab foil is transferred, the tab 2 will still sag as a whole at one place. When the ratio of the depth L1 of the groove 22 to the height L2 of the tab 2 is greater than 0.6, that is, the groove 22 is too deep, at this time, the material between the two welding areas 21 is very little, and this part of the material plays a role of connection and support between the tab and the first side 23 of the tab 2. When this part of the material is too little, when analyzing the force, it can be imagined that one tab 2 becomes two separate tabs 2, and each of these two separate tabs 2 will sag at one place, and the sag problem still cannot be completely solved.
[0046] Table 1
[0047]
[0048] As shown above, Table 1 provides the experimental data of five tabs, including the ratio of the depth L1 of the groove 22 of the tab 2 to the height L2 of the tab 2 of the five tabs and the angles at which the six tab foils sag during transportation. The larger the sag angle, the more serious the sag problem and the greater the impact on the quality of the cell stack.
[0049] In Example 1 and Example 2, the ratio of the depth L1 of the groove 22 of the tab 2 to the height L2 of the tab 2 meets the more optimal value range of 0.4 - 0.6, and the tab 2 no longer has the sag problem.
[0050] The tab of Comparative Example 1 is relatively special. The ratio of the depth L1 of the groove 22 at the tab 2 to the height L2 of the tab 2 is 0.05, which is equivalent to not providing the groove 22. The tab 2 sags during the transportation of the tab foil, and the sag angle is 35°, and the sag area of the tab 2 is severely deformed.
[0051] Grooves 22 are provided at the tabs 2 of the tabs of Comparative Example 2 and Comparative Example 3, but the ratios of the depth L1 of the grooves 22 to the height L2 of the tabs 2 are 0.2 and 0.8 respectively, that is, the groove 22 in Comparative Example 2 is too shallowly provided, and the groove 22 in Comparative Example 3 is too deeply provided. The tabs 2 of the tabs of Comparative Example 2 and Comparative Example 3 also sag during the transportation of the tab foil, but compared with the tab without the groove 22, the sag angles of the tabs 2 of Comparative Example 2 and Comparative Example 3 are smaller.
[0052] The above measurement data prove that the groove 22 provided on the tab 2 does help to reduce the severity of the sagging, prevent the tab 2 from being inserted into the electrode group, and thus improve the safety of the battery cell. Moreover, when the ratio of the depth L1 of the groove 22 of the tab 2 to the height L2 of the tab 2 meets the more optimal range of 0.4 - 0.6, the tab 2 no longer sags, and the sagging problem is fundamentally solved.
[0053] Optionally, along the first direction, the width L3 of the groove 22 and the width L4 of the tab 2 satisfy 0.1 ≤ L3 / L4 ≤ 0.3. If the ratio of the width L3 of the groove 22 to the width L4 of the tab 2 is less than 0.1, the groove 22 is too narrow to reduce the weight of the tab 2 to completely eliminate the sagging phenomenon. When the ratio of the width L3 of the groove 22 to the width L4 of the tab 2 is greater than 0.3, the groove 22 is too wide. When the width of the tab 2 is fixed, an overly wide groove 22 will result in an insufficient width of the welding area 21, causing problems such as restricted current conduction and insufficient connection strength. When the width of the welding area 21 remains unchanged, an overly wide groove 22 will also lead to an insufficient width at the edge of the welding area 21, affecting the welding quality and even causing welding cracking and other problems.
[0054] Optionally, the height L2 of the tab 2 and the width L4 of the tab 2 satisfy 2 ≤ L4 / L2 ≤ 3. If the ratio of the height L2 of the tab 2 to the width L4 of the tab 2 is less than 2, that is, the tab 2 is too high, it will exacerbate the sagging problem of the tab 2. Once the ratio of the height L2 of the tab 2 to the width L4 of the tab 2 is greater than 3, that is, the tab 2 is too wide, it will increase the material cost. The specific value of the height L2 of the tab 2 is limited by the internal space of the battery cell and is not restricted here.
[0055] Optionally, the shortest distance L5 between the side wall of the groove 22 and the welding area 21 has a value range of 2 mm ≤ L5 ≤ 5 mm. That is, there is a more optimal value range of 2 mm - 5 mm for the width of the tab 2 material between the side wall of the groove 22 and the welding area 21. A width less than 2 mm will increase the welding difficulty and is prone to welding crack phenomenon. A width greater than 5 mm will cause a reduction in the width of the welding area 21 or the width of the groove 22. The former will cause problems such as restricted current conduction and insufficient connection strength between the tab 2 and the connector or the terminal post, and the latter will cause the sagging problem of the tab 2 not to be completely solved.
[0056] Optionally, the shortest distance L6 between the welding area 21 and the edge of the first side 23 ranges from 2 mm ≤ L6 ≤ 5 mm. That is, the width of the tab 2 material between the welding area 21 and the edge of the first side 23 has a better range of 2 mm - 5 mm. A width less than 2 mm will also increase the welding difficulty and is prone to welding cracks. A width greater than 5 mm will cause insufficient height of the welding area 21 or excessive overall height of the tab 2. The former will cause problems such as restricted current conduction and insufficient connection strength between the tab 2 and the connector or the terminal post. The latter will exacerbate the problem of the tab 2 sagging.
[0057] Optionally, the shortest distance L7 between the welding area 21 and one side of the tab 2 along the first direction ranges from 2 mm ≤ L7 ≤ 5 mm. That is, the width of the tab 2 material between the side of the welding area 21 far from another welding area 21 and the adjacent edge of the tab 2 has a better range of 2 mm - 5 mm. A width less than 2 mm will also increase the welding difficulty and is prone to welding cracks. A width greater than 5 mm will cause insufficient width of the welding area 21 or excessive overall width of the tab 2. The former will cause problems such as restricted current conduction and insufficient connection strength between the tab 2 and the connector or the terminal post. The latter will increase the weight of the tab 2 and is not conducive to solving the problem of the tab 2 sagging.
[0058] Optionally, in other embodiments, B can be greater than 1. Then, a plurality of grooves 22 are formed between two adjacent welding areas 21, and the plurality of grooves 22 located between two adjacent welding areas 21 are evenly spaced.
[0059] Optionally, in other embodiments, A can be greater than 2 and B is equal to 1. Then, there are more than two welding areas 21, and a groove 22 is formed between any two adjacent welding areas 21. The plurality of grooves 22 are evenly spaced to prevent the weight of the tab 2 from being asymmetric in the width direction and causing one side to sag due to excessive weight. Optionally, the widths of the plurality of grooves 22 are the same. Optionally, the depths of the plurality of grooves 22 are the same. That is, the sizes of the plurality of grooves 22 are the same, which can further ensure the symmetry of the weight of the tab 2 in the width direction.
[0060] Optionally, the groove 22 is a polygonal groove or a semi-circular groove. Optionally, the groove 22 can be a rectangular groove, a trapezoidal groove or a triangular groove. Of course, when it is a trapezoidal groove, the long side of the trapezoidal groove is at the opening. When it is a triangular groove, the long side of the triangular groove is also at the opening.
[0061] Optionally, a second weight reduction notch 221 is formed on the side wall and / or the bottom of the groove 22, and the depth of the second weight reduction notch 221 is less than the depth of the groove 22. Providing the second weight reduction notch 221 can also reduce the weight of the tab 2 and is beneficial to eliminating the sagging phenomenon.
[0062] Optionally, the tab 2 has a third side 25 and a fourth side 26 that are oppositely arranged in the first direction. The third side 25 has a third weight reduction notch 251. Optionally, the fourth side 26 has a fourth weight reduction notch 261. Providing the third weight reduction notch 251 and the fourth weight reduction notch 261 can also reduce the weight of the tab 2, which is beneficial to eliminating the sagging phenomenon.
[0063] Optionally, a plurality of first weight reduction notches 231 are provided. Optionally, in this embodiment, the plurality of first weight reduction notches 231 are continuously arranged to form a serrated notch. Optionally, the serrated notch covers the entire length area of the first side 23.
[0064] Optionally, a plurality of second weight reduction notches 221 are provided. Optionally, in this embodiment, the plurality of second weight reduction notches 221 are continuously arranged to form a serrated notch. Optionally, the serrated notch covers the entire area of the side wall and the bottom of the groove 22.
[0065] Optionally, a plurality of third weight reduction notches 251 are provided. Optionally, in this embodiment, the plurality of third weight reduction notches 251 are continuously arranged to form a serrated notch. Optionally, the serrated notch covers the entire length area of the third side 25 of the tab 2.
[0066] Optionally, a plurality of fourth weight reduction notches 261 are provided. Optionally, in this embodiment, the plurality of fourth weight reduction notches 261 are continuously arranged to form a serrated notch. Optionally, the serrated notch covers the entire length area of the fourth side 26 of the tab 2.
[0067] Optionally, the depth a of the first weight reduction notch 231 ranges from 1 mm ≤ a ≤ 2 mm. Optionally, the depth b of the second weight reduction notch 221 ranges from 1 mm ≤ b ≤ 2 mm. Optionally, the depth c of the third weight reduction notch 251 ranges from 1 mm ≤ c ≤ 2 mm. Optionally, the depth d of the fourth weight reduction notch 261 ranges from 1 mm ≤ d ≤ 2 mm. It should be noted that the depth of the above-mentioned notches refers to the vertical distance between the highest point and the lowest point of the serrations. When the depth of the notch is less than 1 mm, the effect of the notch on reducing the weight of the tab 2 is not obvious and it is not easy to process. When the depth of the notch is greater than 2 mm, it is not conducive to the structural strength at the notch. I'm afraid that when subjected to tensile force, the lowest point of the notch will crack under stress.
[0068] Optionally, in this embodiment, the material of the tab 2 is copper, and the foil material is relatively thin, about 6 μm. Therefore, the tab 2 is very soft and prone to sagging.
[0069] Optionally, positive and negative electrode tabs are respectively provided at both ends of the electrode sheet. The material of the negative electrode tab is copper, and grooves 22 and notches need to be opened according to the above design to prevent the problem of sagging. The material of the positive electrode tab is aluminum, and the thickness of the foil is about 13 μm. No grooves 22 or notches need to be opened, and the problem of sagging will not occur either.
[0070] As Figure 3 shown, the electrode assembly of this battery cell is formed by stacking multiple electrode sheets. When the electrode sheet foil of the electrode assembly of this battery cell is laser die-cut, special-shaped processing is performed on the negative electrode tab. That is, by opening grooves 22 and other methods, the weight of the electrode tab 2 can be reduced, the structural strength of the electrode tab 2 can be improved, and the sagging of the electrode tab 2 during the subsequent transfer of the electrode sheet foil can be prevented. Moreover, reducing the weight of the electrode tab 2 is also beneficial to improving the mass energy density of the battery cell, reducing the usage amount of the foil, and reducing the cost.
[0071] This embodiment also provides a battery cell, including a housing and the above-mentioned electrode assembly of the battery cell, and the electrode assembly of the battery cell is located inside the housing. This battery cell helps to avoid the problem of sagging of the electrode tab 2 and ensure the safety of the battery cell.
[0072] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.
Claims
1. A battery cell group, characterized in that: The invention comprises a multilayer pole piece, wherein the pole piece comprises a pole piece body (1) and a pole ear (2), wherein the pole ear (2) comprises A welding areas (21), wherein the A welding areas (21) are arranged in sequence at intervals along a first direction, A is a positive integer greater than 1, and B grooves (22) are provided between two adjacent welding areas (21), wherein B is a positive integer, and the pole ear (2) has a first side (23) and a second side (24) which are arranged opposite to each other along a second direction, wherein the groove (22) is located on the first side (23), and the second side (24) is connected to the pole piece body (1), and the second direction is perpendicular to the first direction, and a first weight-reducing notch (231) is provided at a position of the first side (23) where the groove (22) is not provided, and the depth of the first weight-reducing notch (231) is less than the depth of the groove (22).
2. The battery cell electrode group according to claim 1, characterized in that: The value of A is 2, the value of B is 1, and along the second direction, the depth L1 of the groove (22) and the height L2 of the tab (2) satisfy 0.4≤L1 / L2≤0.6; and / or, the value of A is 2, the value of B is 1, and along the first direction, the width L3 of the groove (22) and the width L4 of the tab (2) satisfy 0.1≤L3 / L4≤0.3; And / or, the height L2 of the pole lug (2) and the width L4 of the pole lug (2) satisfy 2≤L4 / L2≤3.
3. The battery cell electrode group according to claim 1, characterized in that: The shortest distance L5 between the side wall of the groove (22) and the welding area (21) is in the range of 2 mm ≤ L5 ≤ 5 mm; and / or, the shortest distance L6 between the welding area (21) and the edge of the first side (23) is in the range of 2 mm ≤ L6 ≤ 5 mm; And / or, the shortest distance L7 between the welding area (21) and one side of the electrode tab (2) along the first direction is in the range of 2 mm ≤ L7 ≤ 5 mm.
4. The battery cell electrode group according to claim 1, characterized in that: B is greater than 1, and the plurality of grooves (22) located between two adjacent welding areas (21) are evenly spaced.
5. The battery cell electrode group according to claim 1, characterized in that: A is greater than 2, B is 1, a groove (22) is provided between any two adjacent welding areas (21), a plurality of grooves (22) are evenly spaced, and / or a plurality of grooves (22) have the same width, and / or a plurality of grooves (22) have the same depth.
6. The battery cell electrode group according to any one of claims 1 to 5, characterized in that: The groove (22) is a polygonal groove or a semicircular groove.
7. The battery cell electrode group according to any one of claims 1 to 5, characterized in that: A second weight-reducing notch (221) is provided on the side wall of the groove (22) and / or the bottom of the groove (22), and the depth of the second weight-reducing notch (221) is smaller than the depth of the groove (22); And / or, the pole lug (2) has a third side (25) and a fourth side (26) arranged opposite to each other along the first direction, and the third side (25) has a third weight-reducing notch (251); And / or, the fourth side (26) has a fourth weight-reducing notch (261).
8. The battery cell electrode group according to claim 7, characterized in that: A plurality of the first weight-reducing notches (231) are provided; And / or, the second weight-reducing notch (221) is provided in plurality; And / or, the third weight-reducing notch (251) is provided in plurality; And / or, the fourth weight-reducing gap (261) is provided in plurality.
9. The battery cell electrode group according to claim 7, characterized in that: The depth a of the first weight-reducing notch (231) is in the range of 1 mm ≤ a ≤ 2 mm; And / or, the depth b of the second weight-reducing notch (221) is in the range of 1 mm ≤ b ≤ 2 mm; And / or, the depth c of the third weight-reducing notch (251) is in the range of 1 mm ≤ c ≤ 2 mm; And / or, the depth d of the fourth weight-reducing notch (261) is in the range of 1 mm ≤ d ≤ 2 mm.
10. A battery cell, characterized in that: It comprises a shell and a battery cell pole group as claimed in any one of claims 1 to 9, wherein the battery cell pole group is located in the shell.