Connecting structure of tab and battery cell cover plate and battery cell

Abstract

The invention relates to the technical field of batteries, and particularly discloses a connecting structure of a tab and a battery cell cover plate and a battery cell, and in the connecting structure of the tab and the battery cell cover plate, a pole of the battery cell cover plate is integrated on a cover plate body. The tab is led out from one end of the pole group along the first direction, the tab comprises a plurality of substrates which are stacked along the second direction, the plurality of substrates are welded to form a first welding mark, and the plurality of substrates are connected and conducted through the first welding mark. And at least two second welding marks which are arranged at intervals in the first direction are formed after the pole lugs and the pole columns are welded, the second welding marks are located in the areas where the first welding marks are located, the pole lugs and the pole columns are connected and conducted through the second welding marks, and then circuit connection between the pole group and the pole columns is achieved. According to the invention, the arrangement of a connecting sheet is omitted, the assembly process is reduced, the space is saved, the energy density can be improved, and the cost is low. The invention also provides a battery cell which comprises the connecting structure of the tab and the battery cell cover plate.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a connection structure between a tab and a cell cover, and a battery cell. Background Technology

[0002] Lithium-ion batteries have relatively mature technology and are currently a research hotspot in power batteries. The battery cell, as the core component of a lithium-ion battery, mainly consists of an aluminum casing, a cell cover, and electrode assemblies. The electrode assemblies are housed within the aluminum casing, and the cell cover connects to the aluminum casing to encapsulate the electrode assemblies. The electrode tabs of the electrode assemblies are typically connected to the terminals integrated on the cell cover via connecting tabs. The assembly process is relatively complex, involves many types of components, and results in high production costs. Summary of the Invention

[0003] The purpose of this invention is to provide a connection structure between the electrode tab and the cell cover plate, and a cell, which directly welds the electrode tab of the electrode group to the electrode post, eliminating the need for connecting pieces, reducing assembly processes, saving internal space of the cell, which is beneficial to improving energy density and reducing costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a connection structure between the electrode tab and the cell cover plate, comprising: A battery cell cover plate includes a cover plate body and a terminal post, wherein the terminal post is integrated on the cover plate body; The electrode tab extends from one end of the electrode group along a first direction. The electrode tab includes multiple substrates stacked along a second direction. Each substrate is connected to an electrode of the electrode group. The multiple substrates are welded together to form a first solder mark. The first solder mark is located at one end of the electrode tab away from the electrode group. The electrode tab is welded to the electrode post to form at least two second solder marks spaced apart along the first direction. The second solder marks are located in the area where the first solder mark is located. Wherein, the end of the electrode tab that is away from the electrode group is the top of the electrode tab; along the first direction, the distance between the top of the electrode tab and the second solder mark near the top of the electrode tab is C; The range of C is: 1mm≤C≤3mm.

[0005] Optionally, along a third direction, the distance between the side of the second solder mark opposite to the center of the tab and the side of the first solder mark opposite to the center of the tab is A; The range of values ​​for A is: 1mm ≤ A ≤ 3mm.

[0006] Optionally, in a plane perpendicular to the second direction, the cross-sectional area of ​​the first solder mark is S1, and the sum of the cross-sectional areas of all the second solder marks is S2. The relationship between S1 and S2 satisfies: 0.15≤S2 / S1≤0.3.

[0007] Optionally, the dimension of the first solder mark along the first direction is E, and the dimension of the first solder mark along the third direction is F; wherein, S1 = E × F; The value range of E is: 5mm≤E≤10mm; The value range of F is: 15mm≤F≤20mm.

[0008] Optionally, each of the tabs is provided with two second solder marks, the second solder marks having a dimension D along the first direction and a dimension B along the third direction; wherein, S2 = 2 × D × B; The value range of D is: 1.0mm≤D≤2.5mm; The value of B is in the range of 10mm≤B≤18mm.

[0009] Optionally, along the first direction, the distance between the sides of two adjacent second solder marks that are close to each other is d, and the value of d is in the range of 0.5mm≤d≤1.5mm.

[0010] Optionally, the first solder mark is centrally disposed on the electrode tab along a third direction; at the end of the electrode tab away from the electrode group, the distance between the side of the first solder mark disposed opposite to the electrode tab along a third direction and the adjacent side of the electrode tab disposed opposite to the electrode tab along a third direction is t1; The value range of t1 is: 1.0mm≤t1≤3.0mm.

[0011] Optionally, the end of the electrode tab connected to the electrode group is the root of the electrode tab; along the first direction, the distance between the side of the first solder mark near the electrode group and the root of the electrode tab is G1; The value range of G1 is: 6mm≤G1≤14mm.

[0012] On the other hand, the present invention provides a battery cell including the connection structure between the electrode tab and the battery cell cover plate in any of the above embodiments.

[0013] Optionally, the battery cell includes two electrode groups and a battery cell cover plate. The cover plate body of the battery cell cover plate integrates two terminals, one of which is a positive terminal and the other is a negative terminal. Each of the electrode groups has two tabs leading out from one end along the first direction. The two tabs are respectively connected to the positive terminal and the negative terminal using the above-described connection structure between the tabs and the cell cover plate.

[0014] The beneficial effects of this invention are as follows: This invention provides a connection structure between a tab and a cell cover, including a cell cover, a tab, and a electrode assembly. The cell cover includes a cover body and electrode posts, with the electrode posts integrated onto the cover body. A tab extends from one end of the electrode assembly along a first direction. The tab includes multiple substrates stacked along a second direction, each substrate connecting to an electrode of one electrode assembly. The multiple substrates are welded together to form a first solder mark located at the end of the tab opposite to the electrode assembly, connecting the multiple substrates electrically. After welding the tab to the electrode post, at least two second solder marks are formed at intervals along the first direction, located within the area of ​​the first solder marks, connecting the tab and the electrode post electrically. By directly welding the tab to the electrode post, a circuit connection between the electrode assembly and the electrode post is achieved, eliminating the need for connecting tabs, reducing assembly processes, saving internal space in the cell, improving energy density, and reducing costs.

[0015] This invention also provides a battery cell, including the connection structure between the aforementioned tab and the cell cover plate. By rationally optimizing the relevant process parameters during the welding of the tab and the terminal post, the welding yield during the assembly of the cell cover plate and the tab can be effectively improved, resulting in good safety performance and a high energy density for the battery cell. Attached Figure Description

[0016] Figure 1 This is a front view of the first insulating tape, electrode tabs, and electrode assembly provided in an embodiment of the present invention; Figure 2 This is a left view of the first insulating tape, electrode tabs, and electrode assembly provided in an embodiment of the present invention; Figure 3 This is a front view of the battery cell cover, the first insulating tape, the electrode tabs, and the electrode assembly provided in this embodiment of the invention. Figure 4 for Figure 3 A magnified view of a section at point I; Figure 5 This is a front view of the battery cell cover, first insulating tape, second insulating tape, electrode tabs, and electrode assembly provided in an embodiment of the present invention.

[0017] In the picture: 10. Cell cover plate; 11. Cover plate body; 12. Terminal post; 20. Terminal tab; 201. Top of terminal tab; 202. Root of terminal tab; 21. First solder mark; 22. Second solder mark; 30. Electrode group; 40. First insulating tape; 50. Second insulating tape. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly 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 of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] like Figures 1-4As shown, this embodiment provides a connection structure between a tab and a cell cover, including a cell cover 10, a tab 20, and a pole group 30. The cell cover 10 includes a cover body 11 and a pole post 12, with the pole post 12 integrated on the cover body 11. The tab 20 extends from one end of the pole group 30 along a first direction. The tab 20 includes multiple substrates stacked along a second direction, each substrate connecting to one pole post of the pole group 30. After welding the multiple substrates, a first solder mark 21 is formed. The first solder mark 21 is located at the end of the tab 20 opposite to the pole group 30, and the multiple substrates are connected and conductive through the first solder mark 21. After welding the tab 20 and the pole post 12, at least two second solder marks 22 are formed at intervals along the first direction. The second solder marks 22 are located within the area where the first solder mark 21 is located, and the tab 20 and the pole post 12 are connected and conductive through the second solder marks 22. The aforementioned first direction is... Figure 1 The X-axis direction shown is the second direction. Figure 2 The Y-axis direction is shown in the figure. In this embodiment, the circuit connection between the electrode group 30 and the electrode post 12 is achieved by directly welding the electrode tab 20 to the electrode post 12, which eliminates the need for connecting pieces, reduces the assembly process, saves internal space of the battery cell, helps to improve energy density, and reduces costs.

[0023] The end of the tab 20 facing away from the electrode assembly 30 is the tab top 201. Along the first direction, the distance C between the tab top 201 and the second solder mark 22 near the tab top 201 is defined as 1mm ≤ C ≤ 3mm. For example, C can be 1.0mm, 1.5mm, 2.0mm, 2.5mm, or 3.0mm. By limiting the value of C within the above range, a certain space is maintained between the second solder mark 22 and the tab top 201, ensuring good welding quality between the tab 20 and the electrode post 12 and preventing welding defects such as pinholes.

[0024] Furthermore, along the third direction, the distance between the side of the second solder mark 22 away from the center of the tab 20 and the side of the first solder mark 21 away from the center of the tab 20 is A, and the value of A ranges from 1mm to A ≤ 3mm. The aforementioned third direction is... Figure 1 The Z-axis direction is shown in the figure. For example, the value of A can be 1.0mm, 1.5mm, 2.0mm, 2.5mm, or 3.0mm, etc. By limiting the value of A within the above range, a certain space is provided between the side of the second solder mark 22 along the third direction and the adjacent side of the first solder mark 21 along the third direction. This avoids the risk of poor welding when welding the tab 20 to the pole post 12, and avoids excessive pull-out force on the side of the tab 20 along the third direction, which could lead to tearing. At the same time, it ensures good current flow performance between the tab 20 and the pole post 12.

[0025] See also Figure 1 and Figure 4In a plane perpendicular to the second direction, the cross-sectional area of ​​the first solder mark 21 is S1, and the sum of the cross-sectional areas of all second solder marks 22 is S2. The relationship between S1 and S2 satisfies: 0.15 ≤ S2 / S1 ≤ 0.3. For example, the value of S2 / S1 can be 0.15, 0.20, 0.25, or 0.30, etc. By limiting the value of S2 / S1 within the above range, the welding quality of the second solder marks 22 is ensured to be good, and it is not easy to pull the substrate of the tab 20 along the third direction side, causing partial tearing of the substrate of the tab 20. The connection between the tab 20 and the pole post 12 is reliable, and the overcurrent meets the requirements. Otherwise, when the value of S2 / S1 is too small, the welding pull-out force between the tab 20 and the post 12 is too small, and the tab 20 is prone to separate from the post 12, resulting in low connection strength. When the value of S2 / S1 is too large, the positioning accuracy of the welding position between the tab 20 and the post 12 is required to be high. If the welding position is offset, some of the second weld marks 22 may exceed the range of the first weld mark 21, affecting the current flow effect of the tab 20. In addition, after the tab 20 and the post 12 are welded, abnormalities such as excessive welding pull-out force and tearing of the tab 20 may occur, reducing the reliability of the connection between the tab 20 and the post 12.

[0026] Wherein, the dimension of the first solder mark 21 along the first direction is E, and the dimension of the first solder mark 21 along the third direction is F, S1=E×F. Optionally, the value range of E is: 5mm≤E≤10mm, and the value range of F is: 15mm≤F≤20mm. For example, the value of E can be 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm, etc. The value of F can be 15mm, 16mm, 17mm, 18mm, 19mm, or 20mm, etc. By limiting the values ​​of E and F to the above ranges, the cross-sectional area of ​​the first solder mark 21 in the XZ plane is larger, and the connection between multiple substrates is stable and reliable. In addition, limiting the values ​​of E and F to the above ranges can ensure that the tab 20 can meet the overcurrent requirements.

[0027] Furthermore, in this embodiment, each tab 20 is provided with two second solder marks 22, which are spaced apart along the first direction. The dimension of each second solder mark 22 along the first direction is D, and the dimension of each second solder mark 22 along the third direction is B, S2 = 2 × D × B. Optionally, the value range of D is: 1.0mm ≤ D ≤ 2.5mm, and the value range of B is: 10mm ≤ B ≤ 18mm. For example, the value of D can be 1.0mm, 1.5mm, 2.0mm, or 2.5mm, etc. The value of B can be 10mm, 12mm, 14mm, 16mm, or 18mm, etc. By limiting the values ​​of D and B to the above ranges, it can be ensured that the sum of the cross-sectional areas of all the second solder marks 22 in the XZ plane is large, thereby making the connection between the tab 20 and the pole post 12 more reliable, and the tab 20 is not easy to separate from the pole post 12; at the same time, it can also meet the overcurrent requirements. In addition, it should be noted that a certain gap should be left between the side of the second weld mark 22 along the third direction and the adjacent side of the first weld mark 21 along the third direction, that is, 2×D<E, B<F, so as to facilitate the welding operation and ensure good welding quality of the second weld mark 22.

[0028] See also Figure 4 Along the first direction, the distance between the sides of two adjacent second weld marks 22 that are close to each other is d, and the value of d is in the range of 0.5mm ≤ d ≤ 1.5mm. For example, the value of d can be 0.5mm, 1.0mm, or 1.5mm, etc. By limiting the value of d to the above range, it can be ensured that two adjacent second weld marks 22 will not affect each other during welding, which facilitates the welding operation, and at the same time ensures that the welding quality of each second weld mark 22 is good and welding problems such as pores are not likely to occur.

[0029] Optionally, the first solder mark 21 is centrally located on the tab 20 along a third direction. At the end of the tab 20 opposite to the electrode assembly 30 (i.e., the top 201 of the tab), the distance between the side of the first solder mark 21 opposite to it along the third direction and the adjacent side of the tab 20 opposite to it along the third direction is t1. The value of t1 is in the range of 1.0mm ≤ t1 ≤ 3.0mm. For example, the value of t1 can be 1.0mm, 1.5mm, 2.0mm, 2.5mm, or 3.0mm, etc. By limiting the value of t1 to the above range, a certain space is provided between the first solder mark 21 and the side of the tab 20 along the third direction, avoiding the risk of tearing or other adverse effects during the welding of multiple substrates stacked along the first direction, while also ensuring good alignment of the top 201 of the tab.

[0030] Furthermore, the end of the tab 20 connected to the electrode assembly 30 is the tab root 202. Along the first direction, the distance between the side of the first solder mark 21 closest to the electrode assembly 30 and the tab root 202 is G1, and the value of G1 ranges from 6mm to 14mm. For example, the value of G1 can be 6mm, 8mm, 10mm, 12mm, or 14mm, etc. By limiting the value of G1 to the above range, the distance between the first solder mark 21 and the tab root 202 is relatively large, which can meet the connection requirements between the tab 20 and the electrode post 12, while also minimizing the adverse effects of heat generated during the welding of the tab 20 and the electrode post 12 on the performance of the electrode assembly 30.

[0031] Optionally, see Figures 1-5 The connection structure between the electrode tab and the cell cover plate also includes an insulation component, which includes a first insulating tape 40 and a second insulating tape 50. Each electrode tab 20 has two corresponding first insulating tapes 40, both rectangular in shape, positioned on opposite sides of the electrode tab 20 along the second direction. Each first insulating tape 40 covers one of the opposite end faces of the electrode tab root 202 along the second direction, insulating the electrode tab root 202 from the cover plate body 11 to ensure good cell safety performance. The top 201 of the electrode tab is exposed to facilitate subsequent welding of the electrode tab 20 to the electrode post 12. It should be noted that before welding the electrode post 12 to the electrode tab 20, the first insulating tape 40 is first attached to the electrode assembly 30 and both sides of the electrode tab 20 along the second direction.

[0032] Furthermore, after the electrode post 12 and the electrode tab 20 are welded, a second insulating tape 50 is provided at each electrode tab 20. The second insulating tape 50 is also rectangular, and its width along the third direction is greater than the width of the electrode tab 20 along the third direction. The second insulating tape 50 covers the end face of the electrode tab 20 near the top 201 of the electrode tab. The second insulating tape 50 is bonded to the cell cover plate 10 around its perimeter. The second insulating tape 50 completely covers the first solder mark 21 and the second solder mark 22, and also completely covers the side of the electrode tab 20 near the top 201 of the electrode tab. The side of the second insulating tape 50 near the electrode group 30 partially overlaps with the first insulating tape 40, thereby ensuring that after the electrode tab 20 and the electrode post 12 are assembled, the electrode tab 20 is completely covered by the first insulating tape 40 and the second insulating tape 50, and the electrode tab 20 is well insulated from other structural components, avoiding the risk of accidental short circuit.

[0033] This embodiment also provides a battery cell, including the connection structure between the aforementioned tab and the battery cell cover plate. By reasonably optimizing the relevant process parameters when welding the tab 20 and the terminal post 12, the welding yield during the assembly of the battery cell cover plate 10 and the tab 20 can be effectively improved, resulting in good safety performance and a high energy density for the battery cell.

[0034] Specifically, the battery cell includes two electrode groups 30 and a cell cover plate 10. The cell cover plate 10 includes a cover plate body 11 and two terminals 12. The two terminals 12 are spaced apart along a third direction. One terminal 12 is a positive terminal, and the other terminal 12 is a negative terminal. Each electrode group 30 has two tabs 20 led out from one end along a first direction. The two tabs 20 are a positive tab and a negative tab, respectively. The positive tab and the negative tab are connected to the positive terminal and the negative terminal, respectively, using the aforementioned connection structure between the tabs and the cell cover plate.

[0035] In this embodiment, the battery cell eliminates the need for connecting tabs found in traditional battery cells. The positive tabs of the two electrode groups 30 are directly welded to the positive terminals, and the negative tabs of the two electrode groups 30 are directly welded to the negative terminals. After the battery cell cover plate 10 and the tabs 20 are assembled, the four tabs 20 of the two electrode groups 30 are bent towards each other, and the two electrode groups 30 are joined together and arranged side-by-side. Then, the two electrode groups 30 are installed into the battery cell housing, and the cover plate body 11 is welded to the opening of the housing. The two electrode groups 30 are encapsulated by the battery cell cover plate 10 and the housing. This reduces the battery cell assembly process, saves internal space, significantly reduces the cost of the battery cell, and achieves a higher energy density. Moreover, by adopting the above-mentioned connection structure between the tabs and the battery cell cover plate, the first insulating tape 40 and the second insulating tape 50 can effectively insulate and isolate the tabs 20 from the cover plate body 11, the housing, the electrode groups 30, and other structural components, providing excellent insulation protection and high safety.

[0036] The following uses samples from specific implementation cases to verify the relevant dimensional design of the first solder mark 21 and the second solder mark 22 of the tab 20 in the above-mentioned battery cell. See Table 1 for details.

[0037] Table 1

[0038] As can be seen from the above results, the value ranges of parameters B, D, E, F, and S2 / S1 in Examples 1 to 7 meet their corresponding size limitations. The connection strength at the first solder mark 21 and the second solder mark 22 of the tab 20 is high, the connection between the multilayer substrates of the tab 20 is reliable, and the connection between the tab 20 and the terminal post 12 is reliable. Furthermore, no tearing occurred on the side of the tab 20 along the third direction. After the cell assembly is completed, the current carrying capacity of the tab 20 meets the requirements of high current carrying capacity, and the product is of good quality.

[0039] In Comparative Example 1, the values ​​of parameters B, D, E, F, and S2 / S1 are all less than the minimum value of their respective ranges. At this time, the cross-sectional area of ​​the first solder mark 21 in the XZ plane is small, resulting in insufficient pull-out force between the multilayer substrates and inadequate connection strength between multiple substrates in the tab 20. The sum of the cross-sectional areas of the second solder mark 22 in the XZ plane is also small, leading to insufficient connection strength between the tab 20 and the post 12. The tab 20 is prone to detaching from the post 12, resulting in unstable and unreliable connections. Furthermore, the current carrying capacity of the tab 20 is insufficient to meet the requirements of high current carrying capacity, resulting in defective products.

[0040] In Comparative Examples 2 and 3, the values ​​of parameters B, D, E, F, and S2 / S1 are all greater than the maximum value of their respective ranges. At this time, the cross-sectional area of ​​the first weld mark 21 in the XZ plane is too large, and the distance between the side of the first weld mark 21 along the third direction and the adjacent side of the tab 20 along the third direction is small. If the welding position is offset, part of the first weld mark 21 may easily exceed the edge of the tab 20, resulting in poor welding. At the same time, the sum of the cross-sectional areas of the second weld mark 22 in the XZ plane is also too large. After the tab 20 is welded to the pole post 12, the welding pull-out force is prone to be too large. During the process of closing the two pole groups 30, it is easy to cause abnormal tearing of part of the substrate of the tab 20, resulting in product defects.

[0041] Taking all factors into consideration, when the dimensions of the first solder mark 21 and the second solder mark 22 of the tab 20 in the battery cell meet the above-mentioned dimensional requirements, it can be guaranteed that the tab 20 will not have any tearing problems, the connection strength between the tab 20 and the terminal post 12 will be high, and the current carrying capacity of the tab 20 will be good, meeting the current carrying requirements of large currents, and the battery cell product will be of good quality.

[0042] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A connection structure between a tab and a cell cover plate, characterized in that, include: A battery cell cover plate includes a cover plate body and a terminal post, wherein the terminal post is integrated on the cover plate body; The electrode tab extends from one end of the electrode group along a first direction. The electrode tab includes multiple substrates stacked along a second direction. Each substrate is connected to an electrode of the electrode group. The multiple substrates are welded together to form a first solder mark. The first solder mark is located at one end of the electrode tab away from the electrode group. The electrode tab is welded to the electrode post to form at least two second solder marks spaced apart along the first direction. The second solder marks are located in the area where the first solder mark is located. Wherein, the end of the electrode tab that is away from the electrode group is the top of the electrode tab; along the first direction, the distance between the top of the electrode tab and the second solder mark near the top of the electrode tab is C; The range of C is: 1mm≤C≤3mm.

2. The connection structure between the electrode tab and the cell cover plate according to claim 1, characterized in that, Along a third direction, the distance between the side of the second solder mark away from the center of the electrode tab and the side of the first solder mark away from the center of the electrode tab is A; The range of values ​​for A is: 1mm ≤ A ≤ 3mm.

3. The connection structure between the electrode tab and the cell cover plate according to claim 1, characterized in that, In a plane perpendicular to the second direction, the cross-sectional area of ​​the first solder mark is S1, and the sum of the cross-sectional areas of all the second solder marks is S2. The relationship between S1 and S2 satisfies: 0.15≤S2 / S1≤0.

3.

4. The connection structure between the electrode tab and the cell cover plate according to claim 3, characterized in that, The dimension of the first solder mark along the first direction is E, and the dimension of the first solder mark along the third direction is F; Where S1 = E × F; The value range of E is: 5mm≤E≤10mm; The value range of F is: 15mm≤F≤20mm.

5. The connection structure between the electrode tab and the cell cover plate according to claim 3, characterized in that, Each of the electrode tabs is provided with two second solder marks, the second solder marks having a dimension of D along the first direction and a dimension of B along the third direction; Where S2 = 2 × D × B; The value range of D is: 1.0mm≤D≤2.5mm; The value of B is in the range of 10mm≤B≤18mm.

6. The connection structure between the electrode tab and the cell cover plate according to claim 5, characterized in that, Along the first direction, the distance between the sides of two adjacent second solder marks that are close to each other is d; The value range of d is: 0.5mm≤d≤1.5mm.

7. The connection structure between the electrode tab and the cell cover plate according to claim 1, characterized in that, The first solder mark is centrally located on the electrode tab along a third direction; at the end of the electrode tab away from the electrode group, the distance between the side of the first solder mark located opposite to it along a third direction and the adjacent side of the electrode tab located opposite to it along a third direction is t1; The value range of t1 is: 1.0mm≤t1≤3.0mm.

8. The connection structure between the electrode tab and the cell cover plate according to claim 1, characterized in that, The end of the electrode tab connected to the electrode group is the root of the electrode tab; along the first direction, the distance between the side of the first solder mark near the electrode group and the root of the electrode tab is G1; The value range of G1 is: 6mm≤G1≤14mm.

9. A battery cell, characterized in that, The connection structure between the electrode tab and the cell cover plate as described in any one of claims 1-8.

10. The battery cell according to claim 9, characterized in that, The battery cell includes two electrode groups and a battery cell cover plate. The cover plate body of the battery cell cover plate integrates two terminals, one of which is a positive terminal and the other is a negative terminal. Each of the electrode groups has two tabs leading out from one end along the first direction. The two tabs are respectively connected to the positive terminal and the negative terminal using the connection structure between the tabs and the cell cover plate.

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