An electrode tab length determination method for an electrode, a battery pack, and an electrode

Abstract

The application relates to an electric core, a battery pack and an electric core tab length determination method, and relates to the technical field of power batteries. The electric core comprises a shell, a bare electric core and a plurality of tabs. A battery cavity is formed in the shell. The bare electric core is arranged in the battery cavity, and the bare electric core comprises a multilayer tab structure. The plurality of tabs are connected with the multilayer tab structure respectively, the tab comprises a first end, a bending section and a second end, the bending section is connected between the first end and the second end, the first end is connected with the tab structure, and the second ends of the plurality of tabs are laminated and form a welding part. The length L of the bending section satisfies L=k*(d1+d2), wherein d1 is the distance from the welding part to the end face of the bare electric core along a first direction, d2 is the distance from the welding part to the side edge of the bare electric core along a second direction, the first direction is perpendicular to the second direction, and k is a process coefficient. Based on the above arrangement, the application can quickly and accurately calculate the appropriate length of the tab, and the production and processing efficiency and product yield of the power battery are improved.

Description

Technical Field

[0001] This application relates to the field of power battery technology, specifically to a method for determining the length of a battery cell, a battery pack, and a battery cell tab. Background Technology

[0002] With the continuous development of new energy-related technologies, the application of power batteries is becoming increasingly widespread. At the same time, different application environments are placing different performance requirements on power batteries, and high-energy-density power batteries are an important demand.

[0003] Specifically, existing technologies typically improve the energy density of power batteries by addressing both material properties and the utilization rate of internal cell space. Among these improvements, adjusting the space occupied by the tabs is one possible approach.

[0004] In the existing technology, when adjusting the space occupied by the tab, the length of the tab needs to be adjusted. By shortening the length of the tab, redundancy can be reduced. This not only reduces the space occupied by the tab and improves the space utilization of the power battery, but also avoids problems such as short circuits caused by the redundant tab overlapping with the power battery casing.

[0005] However, it is also important to avoid making the tabs too short. If the tabs are too short, they may break during welding or subsequent cell heating, which will affect the overcurrent capacity of the power battery and also pose a safety risk.

[0006] Therefore, there is an urgent need to provide a method for determining the length of the electrode tab, which can quickly and accurately calculate the appropriate length of the electrode tab, thereby improving the production efficiency and product yield of power batteries. Summary of the Invention

[0007] The purpose of this application is to provide a method for determining the length of battery cells, battery packs, and battery cell tabs, which can quickly and accurately calculate the appropriate length of the tabs, thereby improving the production and processing efficiency and product yield of power batteries.

[0008] To achieve the above objectives, in a first aspect, this application provides a battery cell, comprising a casing, a bare cell, and multiple tabs. A battery cavity is formed inside the casing. The bare cell is disposed within the battery cavity and includes a multi-layer electrode structure. The multiple tabs are respectively connected to the multi-layer electrode structure. Each tab includes a first end, a bent section, and a second end. The bent section connects the first and second ends. The first end is connected to the electrode structure, and the second ends of the multiple tabs are stacked to form a welded portion. The length L of the bent section satisfies… ,in, The distance from the welded portion to the bare cell end face along the first direction is denoted as . The distance from the welded part along the second direction to the side of the bare cell is denoted by k, where the first direction is perpendicular to the second direction, and k is the process coefficient.

[0009] Based on the above embodiments of this application, when the battery cell is assembled and used, if multiple tabs are provided, the multiple tabs are respectively connected to the multi-layer electrode sheets in the bare battery cell, thereby improving the current carrying capacity of the bare battery cell and enabling the battery cell to meet the requirements of fast charging or high power output. Specifically, in the connection, the first end of the multiple tabs is respectively connected to the multi-layer electrode sheet structure, the second end is stacked to form a welding part, and the bending section is bent and arranged according to the relative position of the first end and the welding part.

[0010] Specifically, in this application, by limiting the length of the bending section, it is kept within a suitable range. On the one hand, this avoids the bending section being too long, which would occupy too much space and thus affect the energy density of the cell; it also avoids the safety risks such as short circuits caused by overlapping between the bending section and the casing if the bending section is too long. On the other hand, it avoids the bending section being too short, which would cause the tabs to be too tight, leading to tension and breakage due to shaking during the welding process or cell expansion during subsequent use.

[0011] In summary, this application limits the length of the tab bending section based on the distance between the welding portion and the bare cell end face along a first direction, and the distance from the first end of the tab to the welding portion along a second direction. The first direction corresponds to the direction from the bare cell to the terminal post, and the second direction corresponds to the extension direction of the bare cell end face from the center to the edge. This limits the length of the tab bending section according to the different positions where the tab is assembled, thus keeping the bending section length within a suitable range. This avoids various problems caused by excessively long or short bending sections, quickly and accurately determining the appropriate tab length, and improving the cell manufacturing efficiency and product yield.

[0012] In some embodiments of this application, the process coefficient k ranges from 1.05 to k to 1.3.

[0013] Based on the embodiments described above, in specific calculations, when k = 1, the bending length L is equal to the straight-line distance from the connection point between the tab and the bare cell to the welded portion. This means the bending section of the tab is in a fully taut state. Therefore, by setting k > 1, a certain margin is allowed in the bending section to prevent the tab from breaking or tearing during welding or expansion within the cell. Furthermore, the process coefficient is limited to a range of 1.05 to 1.3 to avoid excessively long bending sections. Excessively long bending sections not only affect the energy density of the cell but also easily cause overlap between the bending section and the casing, leading to safety risks. Therefore, by limiting the process coefficient to a suitable range, the aforementioned problems are avoided.

[0014] In some embodiments of this application, the battery cell further includes a terminal post, and the welding portion is directly or indirectly electrically connected to the terminal post, with the first direction corresponding to the direction from the bare battery cell to the terminal post.

[0015] Based on the embodiments described above, multiple tabs are stacked at the welding point to converge current, and then connected together to the terminal of the battery cell, realizing the connection and conduction from the bare battery cell to the tabs and then to the terminal to achieve the input and output of the battery cell. Specifically, in actual welding, the welding point can be directly welded to the terminal, that is, the welding point is directly electrically connected to the terminal. Alternatively, a structure such as an adapter plate can be provided between the welding point and the terminal. In this case, the welding point is directly welded to the adapter plate, and then connected to the terminal through the adapter plate, that is, the welding point is indirectly electrically connected to the terminal.

[0016] In some embodiments of this application, the distance from the welded portion to the bare cell end face along the first direction is... The range is >0.

[0017] Based on the above embodiments of this application, by setting the distance from the welding part to the bare cell end face along the first direction to be greater than 0, that is, leaving a certain gap between the bare cell and the welding part, it is convenient for subsequent assembly.

[0018] In some embodiments of this application, the distance from the electrode tab to the bare cell connection point along the second direction to the welded portion is... The range is ≥0.

[0019] Based on the above embodiments of this application, the second direction is perpendicular to the first direction. In this case, the first direction corresponds to the direction from the bare cell to the electrode post, and the second direction corresponds to the extension direction of the bare cell end face. When the distance from the electrode tab to the welding part along the second direction is equal to 0, the first end of the electrode tab is positioned directly opposite the welding part along the first direction.

[0020] In some embodiments of this application, the bare battery cell is a stacked battery cell structure or a wound battery cell structure.

[0021] Based on the embodiments described above, the length limitation of the tab bending section described above can be applied to both laminated cell structures and wound cell structures. This limitation ensures that the length of the bending section is within a suitable range, avoiding both excessive redundancy and insufficient allowance that could lead to breakage.

[0022] In some embodiments of this application, the electrode tab is either a positive electrode tab or a negative electrode tab.

[0023] Based on the above embodiments of this application, the length limitation of the bent section of the electrode tab described above can be applied to both positive and negative electrode tabs, thereby making the application of the above technical solution more widespread.

[0024] According to a second aspect of this application, a battery pack is provided, the battery pack including the aforementioned battery cells.

[0025] Based on the above embodiments of this application, the length of the bent section of the electrode tab is limited according to the distance of the welding part relative to the end face of the bare cell along the first direction and the distance of the first end of the electrode tab to the welding part along the second direction. That is, the length of the bent section of the electrode tab is limited according to the different positions where the electrode tab is assembled, thereby limiting the length of the bent section to a suitable range, avoiding various problems caused by the length of the bent section being too long or too short, quickly and accurately determining the appropriate length of the electrode tab, and improving the production and processing efficiency and product yield of the cell.

[0026] According to a third aspect of this application, a method for determining the length of a battery cell tab is provided, applicable to the calculation of the aforementioned battery cell tab length. This method for determining the length of a battery cell tab includes the following steps: Determine the basic parameters, and based on the internal battery cavity dimensions and bare cell dimensions, determine the distance. Maximum allowable value and distance The maximum allowed value; Define the objective function and determine that the length L of the bend should satisfy the following formula (1): L≥ (1); Introducing the process coefficient k, the length L of the bent section is further calculated according to the following formula (2): L (2): Adjust the process, adjust the cell assembly structure, and determine the actual distance. and distance The specific value of the process coefficient k is 1.05≤k≤1.3. Substitute it into the above formula (2) to calculate the length range of the bending section.

[0027] Based on the embodiments described above, in practical use, the distance is first determined according to the dimensions of the bare battery cell and the casing, combined with the assembly process. and distance The numerical value was then introduced, and the length range of the bending section was calculated. For the tabs at different locations within the same cell structure, the distance... The sizes of the electrodes vary, so different length ranges can be calculated for electrodes at different positions, thus determining the appropriate length range for each electrode bending segment and avoiding various problems caused by electrodes that are too long or too short.

[0028] In some embodiments of this application, the method for determining the length of the battery cell tab includes, after the process adjustment steps, the following step: Verification and iteration were conducted by fabricating multiple battery cell samples with varying tab lengths. All tab lengths met the calculated bending segment length range from the adjustment process steps. Subsequently, the breakage of the tabs was tested. Among the tabs whose breakage met the usage requirements, the sample with the shortest tab length was selected as the preferred sample. The corresponding process coefficient k was determined based on the bending segment length L in the preferred sample, and this process coefficient k was solidified as the process standard.

[0029] Based on the above embodiments of this application, the length range of the tab bending section can be determined according to the above method for determining the length of the battery cell tab. Subsequently, multiple battery cell samples are manufactured, and the length of the tab bending section of each battery cell sample meets the calculated length range. Then, the actual application of tab bending sections of different lengths within this range is verified to select the preferred sample as the standard length of the bending section of the battery cell of this specification. The corresponding process coefficient is the standard process coefficient. In subsequent production, processing and assembly processes, production, processing and assembly can be carried out directly according to the standard process coefficient, thereby improving the production efficiency and product yield of the battery cell.

[0030] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the following detailed description to explain the present application, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the battery cell structure provided in the embodiments of this application.

[0032] Figure 2 This is a schematic diagram of the structure of the bare cell and the tab in the battery cell provided in the embodiments of this application.

[0033] Figure 3 This is a flowchart illustrating the method for determining the length of the battery cell tab provided in an embodiment of this application.

[0034] Explanation of reference numerals in the attached figures 1. Casing; 2. Bare cell; 3. Tab; 31. Bending section; 32. Welding section; 33. First tab; 34. Second tab; 4. Terminal post. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] In the description of this application, it should be noted that, unless otherwise stated, the terms "inner," "outer," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0040] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" 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 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 application according to the specific circumstances.

[0041] Existing technologies typically aim to improve the energy density of power batteries by addressing both the specific material properties and the utilization rate of the internal space within the cell. Among these approaches, adjusting the space occupied by the electrode tabs is one possible direction for improving the utilization rate of the internal space.

[0042] In the existing technology, when adjusting the space occupied by the tab, the length of the tab needs to be adjusted. By shortening the length of the tab, redundancy can be reduced. This not only reduces the space occupied by the tab and improves the space utilization of the power battery, but also avoids problems such as short circuits caused by the redundant tab overlapping with the power battery casing.

[0043] However, it is also important to avoid making the tabs too short. If the tabs are too short, they may break during welding or subsequent cell heating, which will affect the overcurrent capacity of the power battery and also pose a safety risk.

[0044] Therefore, there is an urgent need to provide a method for determining the length of the electrode tab, which can quickly and accurately calculate the appropriate length of the electrode tab, thereby improving the production efficiency and product yield of power batteries.

[0045] To address the aforementioned problems in the prior art, this application provides a battery cell, with reference to... Figure 1 and Figure 2 As shown, the battery cell includes a housing 1, a bare cell 2, and multiple tabs 3. A battery cavity is formed inside the housing 1. The bare cell 2 is disposed within the battery cavity and includes a multi-layer electrode structure. The multiple tabs 3 are respectively connected to the multi-layer electrode structure. Each tab 3 includes a first end, a bent section 31, and a second end. The bent section 31 connects the first end and the second end. The first end is connected to the electrode structure, and the second ends of the multiple tabs 3 are stacked to form a welded portion 32. The length L of the bent section 31 satisfies... ,in, The distance from the welded part 32 along the first direction to the end face of the bare cell 2. The distance from the welded part 32 along the second direction to the side of the bare cell 2 is denoted by k, where the first direction is perpendicular to the second direction, and k is a process coefficient.

[0046] Based on the above embodiments of this application, when the battery cell is assembled and used, with multiple tabs 3 provided, the multiple tabs 3 are respectively connected to the multi-layer electrode sheets in the bare battery cell 2, thereby improving the current carrying capacity of the bare battery cell 2, so that the battery cell can meet the requirements of fast charging or high power output. Specifically, in the connection, the first end of the multiple tabs 3 is respectively connected to the multi-layer electrode sheet structure, the second end is stacked to form a welding part 32, and the bending section 31 is bent and arranged according to the relative position of the first end and the welding part 32.

[0047] Specifically, in this application, by limiting the length of the bending segment 31, the length of the bending segment 31 is kept within a suitable range. On the one hand, this avoids the bending segment 31 being too long, which would occupy too much space and thus affect the energy density of the battery cell. It also avoids the safety risks such as short circuits caused by overlapping between the bending segment 31 and the casing 1 if the bending segment 31 is too long. On the other hand, it avoids the bending segment 31 being too short, which would cause the tab 3 to be too tight, leading to breakage due to shaking during welding or expansion of the battery cell during subsequent use.

[0048] In summary, this application limits the length of the bent section 31 of the tab 3 based on the distance between the welding portion 32 and the end face of the bare cell 2 along the first direction, and the distance from the first end of the tab 3 to the welding portion 32 along the second direction. The first direction corresponds to the direction from the bare cell 2 to the terminal post 4, and the second direction corresponds to the extension direction from the center to the edge of the end face of the bare cell 2. This limits the length of the bent section 31 of the tab 3 according to the different positions where the tab 3 is assembled, thus keeping the length of the bent section 31 within a suitable range. This avoids various problems caused by the bent section 31 being too long or too short, quickly and accurately determining the appropriate length of the tab 3, and improving the production efficiency and product yield of the battery cell.

[0049] It should be noted that the multiple tabs 3 mentioned above in this application include two, three, or more tabs 3. Furthermore, the specific number of layers in the electrode structure can be set according to factors such as the actual capacity requirements of the battery cell, and this application does not impose specific limitations on this.

[0050] Specifically, refer to Figure 1 and Figure 2 As shown, multiple tabs 3 are connected to the bare cell 2, and then the second ends are stacked to form a welded portion 32. The innermost tab 3 and the outermost tab 3 are named the first tab 33 and the second tab 34, respectively. Taking the second tab 34 as an example, the distance from the welded portion 32 to the end face of the bare cell 2 along the first direction is... The distance from the connection point of the electrode 3 and the bare cell 2 along the second direction to the welding part 32 That is, the distance from the perpendicular point of the welding part 32 on the end face of the bare cell 2 along the first direction to the connection position of the second tab 34 and the bare cell 2. Then, according to the Pythagorean theorem, the straight-line distance c from the connection position of the second tab 34 and the bare cell 2 to the welding part 32 can be calculated as c = However, if the length of the bent section 31 of the second tab 34 is set according to the straight distance c, the bent section 31 will be in a completely taut state. Therefore, a process coefficient k is introduced at this time to adjust the length margin when the bent section 31 is laid out.

[0051] Furthermore, the specific range of the process coefficient can be selected according to the assembly requirements. In some embodiments of this application, the range of the process coefficient k can be set to 1.05 ≤ k ≤ 1.3. During the specific processing, the specific parameters can be selected within this range according to the different cell structures or different processing techniques. For example, when the cell is set as a laminated cell structure, the process coefficient k can be selected as 1.1, and when the cell is set as a wound core structure, the process coefficient k can be selected as 1.25.

[0052] Continuing with the example of the second tab 34, after introducing the process coefficient k, in the specific calculation, when k=1, the length L of the bent section 31 is equal to the straight-line distance c from the connection point of the second tab 34 and the bare cell 2 to the welding part 32. That is, the bent section 31 of the second tab 34 will be in a completely taut state. Therefore, by setting k>1, a certain margin is allowed in the bent section 31 to prevent the tab 3 from being pulled apart or torn during welding or expansion inside the cell. Furthermore, the process coefficient is limited to a range of 1.05 to 1.3 to avoid the bent section 31 from being too long. An excessively long bent section 31 not only affects the energy density of the cell but also easily causes the bent section 31 to overlap with the casing 1, leading to safety risks. Therefore, by limiting the range of the process coefficient to a suitable range, the above problems are avoided.

[0053] Similarly, the length range of the bent segment 31 in the first electrode 33 can also be determined in the same way as described above.

[0054] For the other tabs 3 between the first tab 33 and the second tab 34, the length range of the bending segment 31 in each tab 3 can be calculated either by the above method or by determining the length range of the bending segment 31 by decreasing the length. Specifically, since the connection position of each tab 3 to the bare cell 2 is located at the end face of the bare cell 2, the distance from the welding part 32 to the end face of the bare cell 2 along the first direction is calculated for each tab 3. All are the same, except that the distance from the connection point of the tab 3 and the bare cell 2 along the second direction to the welding part 32 is the same. There are differences; the closer the connection point between the tab 3 and the bare cell 2 is to the welding part 32, the further away the perpendicular point on the end face of the bare cell 2 along the first direction is from the welding part 32. The smaller the value, the smaller the calculated length L of the bent segment 31. Based on this, it can be directly set that starting from the first tab 33 and the second tab 34, the closer the connection position of the tab 3 to the bare cell 2 is to the perpendicular point along the first direction on the end face of the bare cell 2, the smaller the length L of the bent segment 31, thus eliminating the need for calculating the length of the bent segment 31 in each of the intermediate tabs 3. The specific decreasing length can be set according to the actual situation, and this application does not impose specific restrictions on it.

[0055] Furthermore, it should be noted that the bare cell 2 mentioned above in this application can be either a laminated cell structure or a wound cell structure.

[0056] Based on the embodiments described above, the length limitation of the bent section 31 of the tab 3 described above can be applied to both laminated cell structures and wound cell structures. This limitation ensures that the length of the bent section 31 is within a suitable range, avoiding both excessive redundancy and insufficient margin that could lead to breakage.

[0057] In the specific production and processing process, the housing 1 can be adapted to different structures of the bare cell 2. For example, when the bare cell 2 is set as a laminated cell structure, the housing 1 can be set as a rectangular cube structure. When the bare cell 2 is set as a wound core structure, the housing 1 can be set as a cylindrical or other structure. The specific configuration can be made according to the actual situation, and this application does not impose any specific restrictions on it.

[0058] Similarly, in some embodiments of this application, the tab 3 can be either a positive tab 3 or a negative tab 3.

[0059] Based on the above embodiments of this application, the length limitation of the bent section 31 of the tab 3 described above can be applied to both the positive tab 3 and the negative tab 3, thereby making the application of the above technical solution more extensive.

[0060] In specific configurations, the positive electrode tab 3 and the negative electrode tab 3 are usually made of different materials, for example, aluminum foil for the positive electrode tab 3 and copper foil for the negative electrode tab 3. Since the elastic modulus and other parameters of aluminum foil and copper foil differ, it may affect the tensile strength of the positive and negative electrode tabs 3. Therefore, the length allowance required for the bending section 31 of the positive and negative electrode tabs 3 will differ, necessitating fine-tuning of the process coefficient. When the tensile strength of the foil is higher, the length of the corresponding bending section 31 can be appropriately shortened, i.e., the process coefficient value can be reduced to decrease redundancy. Conversely, when the tensile strength of the foil is lower, the length of the corresponding bending section 31 can be appropriately extended, i.e., the process coefficient value can be increased to prevent tearing of the bending section 31. Specific adjustments can be made according to actual circumstances, and this application does not impose specific limitations in this regard.

[0061] refer to Figure 1 As shown in some embodiments of this application, the battery cell may further include a terminal post 4, and the welding part 32 is directly or indirectly electrically connected to the terminal post 4, with the first direction corresponding to the direction from the bare battery cell 2 to the terminal post 4.

[0062] Based on the embodiments described above, multiple tabs 3 are stacked at the welding portion 32 to converge current, and then connected together to the terminal post 4 of the battery cell, realizing the connection and conduction from the bare battery cell 2 to the tabs 3 and then to the terminal post 4, thereby realizing the input and output of the battery cell. Specifically, in actual welding, the welding portion 32 can be directly welded and fixed to the terminal post 4, that is, the welding portion 32 is directly electrically connected to the terminal post 4. Alternatively, a structure such as an adapter plate can be provided between the welding portion 32 and the terminal post 4. In this case, the welding portion 32 is directly welded to the adapter plate, and then connected to the terminal post 4 through the adapter plate, that is, the welding portion 32 is indirectly electrically connected to the terminal post 4.

[0063] refer to Figure 2 As shown in some embodiments of this application, the distance from the welded portion 32 to the end face of the bare cell 2 along the first direction is... The range can be >0.

[0064] Based on the above embodiments of this application, the first direction corresponds to the direction from the bare cell 2 to the electrode post 4. By setting the distance from the welding part 32 along the first direction to the end face of the bare cell 2 to be greater than 0, that is, a certain gap is left between the bare cell 2 and the welding part 32 to facilitate subsequent assembly.

[0065] In some embodiments of this application, the distance from the connection point of the tab 3 and the bare cell 2 along the second direction to the welding part 32 is... The range can be ≥0.

[0066] Based on the above embodiments of this application, the second direction is perpendicular to the first direction. In this case, the first direction corresponds to the direction from the bare cell 2 to the electrode post 4, and the second direction corresponds to the extension direction of the end face of the bare cell 2. When the distance from the connection position of the electrode tab 3 and the bare cell 2 along the second direction to the welding part 32 is equal to 0, the first end of the electrode tab 3 is positioned directly opposite the welding part 32 along the first direction.

[0067] Specifically, taking the second tab 34 as an example, the welding part 32 is configured as an L-shaped structure. One end of the L-shaped structure is welded and fixed to the electrode post 4 along the second direction, and the other end extends towards the bare cell 2 along the first direction. At this time, this end is directly opposite the connection position between the second tab 34 and the bare cell 2 along the first direction. The distance of the second tab 34 at this time is... It is 0.

[0068] Furthermore, it should be noted that the battery cell in this application is not limited to the above structure. In actual use, the battery cell may also include structures such as explosion-proof valves, and the specific configuration can be determined according to actual functional requirements. This application does not impose any specific limitations in this regard.

[0069] Based on the above technical solutions, this application embodiment also provides a battery pack, which includes the above-mentioned battery cells.

[0070] Based on the above embodiments of this application, the length of the bent section 31 of the tab 3 is limited according to the distance of the welding part 32 relative to the end face of the bare cell 2 along the first direction and the distance of the first end of the tab 3 to the welding part 32 along the second direction. That is, the length of the bent section 31 of the tab 3 is limited according to the different positions where the tab 3 is assembled, thereby limiting the length of the bent section 31 to a suitable range, avoiding various problems caused by the length of the bent section 31 being too long or too short, quickly and accurately determining the appropriate length of the tab 3, and improving the production and processing efficiency and product yield of the cell.

[0071] Furthermore, the battery pack of this application is not limited to the above structure. In actual use, the battery pack also includes a battery box and a liquid cooling plate, etc. Multiple cells are grouped together and encapsulated in the battery box, and the liquid cooling plate abuts against the ends of the cells for heat dissipation and cooling. The specific structure of the battery pack can be set with reference to the prior art, and this application does not impose specific limitations on it.

[0072] Based on the above technical solutions, this application also provides a method for determining the length of the battery cell tab 3, applicable to the calculation of the length of the battery cell tab 3 mentioned above, for reference. Figure 3 As shown, the method for determining the length of the battery cell tab includes the following steps: S0010 Determine the basic parameters, and determine the distance based on the internal battery cavity dimensions of casing 1 and the dimensions of bare battery cell 2. Maximum allowable value and distance The maximum allowed value; S0020 defines the objective function and determines that the length L of the bent segment 31 should satisfy the following formula (1): L≥ (1); S0030 introduces a process coefficient, k, and further calculates the length L of the bent section 31 according to the following formula (2): L (2): S0040 Adjust the process, adjust the cell assembly structure, and determine the actual distance. and distance The specific value of the process coefficient k is 1.05≤k≤1.3. Substitute it into the above formula (2) to calculate the length range of the bending section 31.

[0073] Based on the embodiments described above in this application, in actual use, the distance is first determined according to the dimensions of the bare battery cell 2 and the casing 1, combined with the assembly process. and distance The numerical value was then introduced. Subsequently, a process factor was introduced to calculate the length range of the bent section 31. For the tabs 3 at different locations within the same cell structure, the distance... The sizes of the electrodes vary, so different length ranges can be calculated for each electrode 3 at different positions, thus determining a suitable length range for each bent segment 31 of the electrode 3 and avoiding various problems caused by the electrode 3 being too long or too short.

[0074] Furthermore, it should be noted that the length of the tab 3 includes the sum of the length of the first end, the length of the second end, and the length of the bent section 31. The method for determining the length of the tab 3 described above in this application only includes determining the length of the bent section 31 in the tab 3, while the lengths of the first end and the second end can be determined according to the assembly process. Also, for the same battery cell, the lengths of the first end and the second end of different tabs 3 can usually remain consistent. Moreover, the lengths of the first end and the second end do not affect the length redundancy of the tab 3, nor do they affect the breakage of the tab 3; therefore, only the length of the bent section 31 needs to be determined.

[0075] In some embodiments of this application, the method for determining the length of the battery cell tab includes, after the process adjustment steps, the following step: S0050 Verification and Iteration: Multiple battery cell samples were fabricated, each with a different tab 3 length. The tab 3 lengths all met the length range of the bending segment 31 calculated in the adjustment process steps. Subsequently, the breakage of the tab 3 was tested. Among the tab 3 samples with breakage conditions that met the usage requirements, the sample with the shortest tab 3 length was selected as the preferred sample. The corresponding process coefficient k was determined based on the length L of the bending segment 31 in the preferred sample, and the process coefficient k was solidified as the process standard.

[0076] Based on the above embodiments of this application, the length range of the bent section 31 of the tab 3 can be determined according to the above method for determining the length of the battery cell tab. Subsequently, multiple battery cell samples are manufactured, and the length of the bent section 31 of the tab 3 of the battery cell samples all meet the calculated length range. Then, the actual application of the bent section 31 of the tab 3 of different lengths within this range is verified, so as to select the preferred sample as the standard length of the bent section 31 of the battery cell of this specification. The corresponding process coefficient is the standard process coefficient. In the subsequent production, processing and assembly process, production and processing can be directly carried out according to the standard process coefficient, thereby improving the production and processing efficiency and product yield of the battery cell.

[0077] Specifically, when selecting, first screen out the tabs 3 whose fracture conditions meet the usage requirements, and then select the shortest tab 3 in this part of the tabs 3. At this time, the selected tab 3 can reduce the possibility of fracture during welding and use, and also reduce the redundancy of the tab 3 length.

[0078] Specifically, in an exemplary embodiment provided in this application, the bare battery cell 2 is configured as a wound core structure, and the length of the bent section 31 of the second tab 34 is calculated as an example.

[0079] First, the maximum distance from the end of the core to the inner top surface of the housing 1 can be measured and determined to be 3.5mm, which is the distance... The maximum value is 3.5mm. The maximum distance from the second end of the tab 3 to the side wall of the housing 1 is 2.0mm, which is the distance... The maximum value is 2.0 mm.

[0080] The distance was then selected based on factors such as installation requirements. The specific value is 3.0mm, distance. The specific value is 1.5mm. Then, the straight-line distance c from the connection point of the second electrode 34 and the bare cell 2 to the welding part 32 is calculated. The calculated result is approximately 3.35 mm. Therefore, the length L of the bent section 31 should be greater than 3.35 mm.

[0081] Then, the process coefficient k is introduced, with a value range of 1.05-1.3. The calculated length L of the bending section 31 should be 3.52mm-4.36mm.

[0082] Finally, a sample model was produced. During assembly, the assembly distance between the bare cell 2 and the casing 1 was adjusted according to the above parameters, and the length of the bent section 31 of the second tab 34 was set according to the above length. It was ultimately determined that when the process coefficient was approximately 1.2 and the length of the bent section 31 was approximately 4.02 mm, the possibility of the second tab 34 developing microcracks or breaking was minimized. Therefore, the distance... It is 3mm, the distance The standard production process parameters for this type of battery cell are determined to be 1.5mm and k=1.2.

[0083] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0084] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0085] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.

Claims

1. A battery cell, characterized in that, The battery cell includes: The casing has a battery cavity formed inside; A bare cell is disposed inside the battery cavity, and the bare cell includes a multi-layer electrode structure; Multiple tabs are provided, and the multiple tabs are respectively connected to the multilayer electrode structure. Each tab includes a first end, a bent section, and a second end. The bent section is connected between the first end and the second end. The first end is connected to the electrode structure. The second ends of the multiple tabs are stacked and form a welded part. The length L of the bent segment satisfies , wherein The distance from the welded portion along the first direction to the end face of the bare cell, the The distance from the welded portion to the side of the bare cell along the second direction is given by k, where the first direction is perpendicular to the second direction, and k is a process coefficient.

2. The battery cell according to claim 1, characterized in that, The range of the process coefficient k is 1.05≤k≤1.

3.

3. The battery cell according to claim 1, characterized in that, The battery cell also includes a terminal post, and the welding part is directly or indirectly electrically connected to the terminal post. The first direction corresponds to the direction from the bare battery cell to the terminal post.

4. The battery cell according to claim 3, characterized in that, The distance from the welded portion to the bare cell end face along the first direction The range is >

0.

5. The battery cell according to claim 3, characterized in that, The distance from the connection point between the electrode tab and the bare battery cell along the second direction to the welding part The range is ≥0.

6. The battery cell according to any one of claims 1-5, characterized in that, The bare battery cell is a stacked cell structure or a wound cell structure.

7. The battery cell according to claim 6, characterized in that, The electrode tab can be either a positive electrode tab or a negative electrode tab.

8. A battery pack, characterized in that, The battery pack includes cells as described in any one of claims 1-7.

9. A method for determining the length of a battery cell tab, applicable to the calculation of the length of a battery cell tab as described in any one of claims 1-7, characterized in that, The method for determining the length of the battery cell tab includes the following steps: Determine the basic parameters, and based on the internal battery cavity dimensions and bare cell dimensions, determine the distance. Maximum allowable value and distance The maximum allowed value; Define the objective function and determine that the length L of the bend should satisfy the following formula (1): L≥ （1）； Introducing the process coefficient k, the length L of the bent section is further calculated according to the following formula (2): L （2）： Adjust the process, adjust the cell assembly structure, and determine the actual distance. and distance The specific value of the process coefficient k is 1.05≤k≤1.

3. Substitute it into the above formula (2) to calculate the length range of the bending section.

10. The method for determining the length of the battery cell tab according to claim 9, characterized in that, The method for determining the length of the battery cell tab includes, after the adjustment process step, the following step: Verification and iteration were conducted, and multiple battery cell samples were fabricated. Each battery cell sample had a different tab length, and the tab length of each sample met the length range of the bending section calculated in the adjustment process steps. Subsequently, the breakage of the tabs was tested. Among the tabs whose breakage met the usage requirements, the sample with the shortest tab length was selected as the preferred sample. The corresponding process coefficient k was determined based on the length L of the bending section in the preferred sample, and the process coefficient k was solidified as the process standard.

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