Electrode assembly, battery, battery pack and design method for electrode assembly

Abstract

Provided in the present application are an electrode assembly, a battery, a battery pack and a design method for an electrode assembly. The electrode assembly comprises an electrode sheet structure and at least one tab structure, wherein the tab structure comprises a plurality of tabs, which are all disposed on one side of the electrode sheet structure and are connected to the electrode sheet structure; and the dimensions of at least two adjacent tabs are different.

Description

Electrode assembly, battery, battery pack and electrode assembly design method

[0001] This application claims priority to Chinese patent applications filed on November 21, 2024, with application number 202411676417.X; filed on November 19, 2024, with application number 202422836055.8; and filed on July 31, 2024, with application number 202421847945.2, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to an electrode assembly, a battery, a battery pack, and a design method for the electrode assembly. Background Technology

[0003] Lithium-ion batteries are metastable systems and are highly sensitive to temperature; excessively high temperatures significantly accelerate battery degradation. In related technologies, to control the temperature of lithium-ion batteries, the internal resistance can be reduced by increasing the number of electrode layers, thereby increasing the uniformity of current density distribution, reducing polarization during charging and discharging, and lowering the overall battery temperature. Invention Overview

[0004] However, due to the increased number of tab layers, it is difficult to ensure that each tab layer is welded together during the battery assembly process, and it is also difficult to ensure that the welding range between multiple tabs is consistent, resulting in inconsistent internal resistance of the battery and thus poor battery consistency.

[0005] In a first aspect, this application proposes an electrode assembly, which includes:

[0006] Electrode structure; and

[0007] At least one electrode structure, including multiple electrodes, all of which are disposed on one side of the electrode structure and connected to the electrode structure;

[0008] Among them, at least two adjacent tabs have different dimensions.

[0009] Secondly, this application proposes a battery comprising:

[0010] At least one electrode assembly; and

[0011] The cover plate assembly is connected to the tab structure of the electrode assembly.

[0012] Thirdly, this application proposes a battery pack, which includes a battery.

[0013] Fourthly, this application proposes an electrode assembly design method for use in batteries, the method comprising:

[0014] Based on the battery design parameters, obtain the maximum and minimum height of the tabs;

[0015] Along the winding direction, the height of the tabs located at odd positions has a opposite gradient trend to the height of the tabs located at even positions, and the projections of all tabs welded to the tab connection portion of the same core in the first direction at least partially overlap. Beneficial effects

[0016] The electrode assembly provided in this application includes an electrode sheet structure and at least one tab structure. The tab structure includes multiple tabs, each of which is disposed on one side of the electrode sheet structure and connected to it. At least two adjacent tabs have different dimensions. The electrode assembly provided in this application, by providing tabs of different sizes in the tab structure, allows multiple tabs of different sizes to be stacked together. This facilitates the clamping of all tabs by the tooling fixtures used in related technologies, ensuring that after the tab structure is bent, multiple layers of tabs are welded together during ultrasonic welding. This results in the ends of the multiple tabs facing away from the tab structure being substantially aligned, and the welding range between the multiple tabs being consistent, thus avoiding the risk of incomplete welding. Attached Figure Description

[0017] Figure 1 is a perspective view of the battery internal electrode assembly provided in an embodiment of this application;

[0018] Figure 2 is an enlarged schematic diagram of part A in Figure 1;

[0019] Figure 3 is a schematic diagram of the internal electrode assembly of the battery provided in an embodiment of this application;

[0020] Figure 4 is a schematic diagram of the structure of the tab body provided in an embodiment of this application;

[0021] Figure 5 is a schematic diagram of the arrangement of some of the electrode bodies in the electrode structure provided in the embodiment of this application;

[0022] Figure 6 is a graph showing the temperature change of the terminals when the battery provided in the embodiment of this application and the battery in the related technology are charged at the nominal capacity current;

[0023] Figure 7 is a graph showing the temperature change of a large area of ​​the battery when it is charged at the nominal capacity current, as provided in the embodiments of this application and in related technologies.

[0024] Figure 8 is a graph showing the change of DC internal resistance during charging of the battery provided in the embodiments of this application and the battery in related technologies.

[0025] Figure 9 is a graph showing the change of DC internal resistance of the battery provided in the embodiments of this application and the battery in related technologies during discharge;

[0026] Figure 10 is a schematic diagram of the structure of the electrode assembly provided in an embodiment of this application;

[0027] Figure 11 is a schematic diagram of a tab structure provided in an embodiment of this application;

[0028] Figure 12 is a schematic diagram of a tab structure provided in an embodiment of this application;

[0029] Figure 13 is a schematic diagram of a tab structure provided in an embodiment of this application;

[0030] Figure 14 is a schematic diagram of the welding of the battery provided in an embodiment of this application;

[0031] Figure 15 is a bottom view of Figure 14;

[0032] Figure 16 is a schematic diagram of the structure of the electrode assembly provided in an embodiment of this application;

[0033] Figure 17 is a schematic diagram of the structure of the main body provided in the embodiment of this application when it is wound to form a core;

[0034] Figure 18 is a schematic diagram of the structure of the main body provided in the embodiment of this application when it is wound to form a core and the tabs are bent and welded to the connecting piece;

[0035] Figure 19 is a top view of the winding core provided in an embodiment of this application;

[0036] Figure 20 is a cross-sectional view of the battery provided in an embodiment of this application;

[0037] Figure 21 is a partial structural diagram of the core-wrapped core before core assembly provided in an embodiment of this application;

[0038] Figure 22 is a schematic diagram of the structure of the connecting piece provided in an embodiment of this application;

[0039] Figure 23 is a flowchart illustrating the electrode assembly design method according to an embodiment of this application;

[0040] Figure 24 is a flowchart illustrating the method for obtaining the maximum and minimum height of the tabs provided in an embodiment of this application;

[0041] Figure 25 is a flowchart illustrating the method for obtaining the spacing between two core packages before they are joined, as provided in an embodiment of this application.

[0042] Figure 26 is a flowchart illustrating the method for obtaining the maximum height of the tab provided in an embodiment of this application.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1. Electrode structure; 11. Electrode body; 10. Connecting end; 2. Tab structure; 21. Tab; 3. First side; 4. Second side; 5. Welding surface;

[0045] 10. Winding body; 11A. Positive electrode plate; 12. Separator; 13. Negative electrode plate; 2A. Positive electrode tab group; 3A. First electrode tab group; 4A. Second electrode tab group; 5A. Negative electrode tab group; 6. Arc shape; 7. Chamfer; 8. Connecting piece; 81. Positive electrode connecting piece; 82. Negative electrode connecting piece.

[0046] 1000 - Electrode assembly, 110 - Main body, 21 - Electrode tab, 130 - Winding start end, 140 - Winding end, 160 - Proximity end, 20 - Core, 210 - Winding center surface, 30 - Housing, 310 - Housing cover, 410 - Connecting ear, 50 - Core package. Embodiments of the present invention

[0047] This application proposes an electrode assembly 1000, which includes an electrode structure 1 and at least one tab structure 2. The tab structure 2 includes a plurality of tabs 21, which are all disposed on one side of the electrode structure 1 and connected to the electrode structure 1; wherein, at least two adjacent tabs 21 have different dimensions.

[0048] In the technical solution of this application, by providing electrodes 21 of different sizes in the electrode structure 2, multiple electrodes 21 of different sizes are stacked together, so that the tooling fixtures in related technologies can clamp them together, ensuring that after the electrode structure 2 is bent, multiple layers of electrodes 21 are welded together during ultrasonic welding, so that the ends of the multiple electrodes 21 away from the electrode structure 2 after bending are basically aligned with each other, and the welding range between the multiple electrodes 21 is consistent, so as to avoid the risk of missed welding.

[0049] Based on this, different embodiments of this application will be described below.

[0050] Please refer to Figures 1 to 9, which show some embodiments of the electrode assembly 1000 proposed in this application.

[0051] In Figures 1 to 9, the X direction is the third direction, the Y direction is the first direction, and the Z direction is the second direction. The first direction Y and the second direction Z intersect each other and are perpendicular to the third direction X. In one embodiment of this application, the first direction Y, the second direction Z, and the third direction X are mutually perpendicular to each other.

[0052] Please refer to Figures 1 to 3. In some embodiments of this application, the electrode assembly 1000 includes an electrode structure 1 and at least one tab structure 2, wherein the tab structure 2 is located at one end of the electrode structure 1 and is connected to the electrode structure 1.

[0053] The electrode structure 1 includes a plurality of electrode bodies 11 stacked along a first direction Y. In one embodiment, the plurality of electrode bodies 11 are integrally formed and wound together to form the electrode structure 1; in another embodiment, the plurality of electrode bodies 11 are stacked.

[0054] The multiple electrode bodies 11 are stacked together. This can be because each electrode body 11 exists independently and there is no connection between two adjacent electrode bodies 11; or the electrode bodies 11 can be bent back and forth in the first direction Y, such that at least a portion of the bent electrode bodies 11 can be opposite each other in the first direction Y. Based on the bending of the electrode bodies 11 back and forth in the first direction Y, the multiple electrode bodies 11 are stacked together.

[0055] In one embodiment of this application, multiple electrode bodies 11 are integrally formed and wound together to form an electrode structure 1. That is, in this embodiment, the electrode assembly 1000 is formed by winding a positive electrode, a negative electrode, and a separator. The electrode body 11 is part of the structure of the positive electrode and the negative electrode. The tab 21 connected to the positive electrode is the positive tab, and the tab 21 connected to the negative electrode is the negative tab.

[0056] Each electrode body 11 includes a connecting end 10 in the second direction Z. The electrode tab structure 2 includes multiple tabs 21, which correspond one-to-one with the multiple electrode bodies 11. When the electrode tab structure 2 is not bent, the tab 21 is connected to the connecting end 10 of the corresponding electrode body 11 and extends along the second direction Z. That is, in this embodiment, one tab 21 is provided on each electrode body 11. By increasing the number of tabs 21 in the electrode assembly 1000, the internal resistance of the battery is reduced, which balances the current density, reduces the temperature during battery operation, and improves battery performance. The multiple tabs 21 are naturally stacked during the winding process of the electrode assembly 1000, so as not to affect the production cycle of the production line.

[0057] Among them, at least two adjacent tabs 21 have different dimensions.

[0058] By providing electrodes 21 of different sizes in the electrode structure 2, multiple electrodes 21 of different sizes are stacked together to facilitate the clamping of all the tooling fixtures in the related technology. This ensures that after the electrode structure 2 is bent, the multiple layers of electrodes 21 are welded together during ultrasonic welding, so that the ends of the multiple electrodes 21 away from the electrode structure 2 after bending are basically aligned with each other, and the welding range between the multiple electrodes 21 is consistent, so as to avoid the risk of missed welding.

[0059] In some embodiments of this application, in two adjacent tabs 21, the orthogonal projection of one tab 21 in the first direction Y falls completely on the other tab 21. That is, this arrangement can increase the welding area between two adjacent tabs 21, thereby improving the consistency of the battery internal resistance.

[0060] In some embodiments of this application, the electrode structure includes a welding surface 5 located in the first direction Y. The welding surface 5 is configured to be welded to the output electrode, that is, the welding surface 5 is directly welded to the electrode post on the cover plate assembly or indirectly welded to the electrode post through a connecting piece.

[0061] In this embodiment, the size of the tab 21 closer to the welding surface 5 is larger than the size of the tab 21 farther from the welding surface 5. In the process of welding multiple tabs 21 to the cover plate assembly of the battery and then inserting the electrode assembly 1000 into the casing, it is necessary to adjust the positional relationship between the electrode assembly 1000 and the cover plate assembly. That is, multiple tabs 21 will be bent. Since the sizes of multiple tabs 21 are different, the size of one or more tabs 21 closer to the welding surface 5 is larger than the size of one or more tabs 21 farther from the welding surface 5. When multiple tabs 21 are bent, the risk of the tabs 21 tearing or being inserted upside down can be reduced.

[0062] In some embodiments of this application, the dimensions of a plurality of tabs 21 decrease sequentially in the first direction Y and in the second direction Z. Since the electrode structure 1 includes a welding surface 5 in the first direction Y, in this embodiment, the dimensions of the plurality of tabs 21 decrease sequentially in the direction away from the welding surface 5.

[0063] Multiple tabs 21 decrease in size sequentially in the second direction Z, meaning that the dimensions of the multiple tabs 21 are different. By setting tabs 21 of different sizes in the tab structure 2, multiple tabs 21 of different sizes are stacked together, so that the tooling fixtures in related technologies can clamp the multiple tabs 21 together, ensuring that after the tab structure 2 is bent, multiple layers of tabs 21 are welded together during ultrasonic welding, so as to avoid the risk of incomplete welding. At the same time, it can also reduce the risk of the tabs 21 tearing or inverting when multiple tabs 21 are bent.

[0064] Furthermore, since the dimensions of the multiple tabs 21 decrease sequentially in the first direction Y, the safety risk of short circuits caused by the tabs 21 being inserted into the electrode structure 1 or overlapping with the cover plate assembly of the battery due to the excessive size of some tabs 21 can be reduced.

[0065] Please refer to Figure 4. In some embodiments of this application, the length of the tab 21 in the second direction Z is S1; wherein, S1 satisfies: 15mm≤S1≤23mm. That is, in this embodiment, S1 satisfies the range of 15mm≤S1≤23mm to ensure that multiple tabs 21 in the tab structure 2 can be welded together, and the welding range between multiple tabs 21 is complete and consistent. If S1 is less than 15mm, there may be a risk of incomplete welding between multiple tabs 21. If S1 is greater than 23mm, the tab 21 may be too long, causing the tab 21 to be inserted into the electrode structure 1 or overlap with the battery cover assembly, resulting in a short circuit safety risk.

[0066] The value of S1 can be 15mm, 15.2mm, 15.4mm, 15.6mm, 15.8mm, 16mm, 16.2mm, 16.4mm, 16.6mm, 16.8mm, 17mm, 17.2mm, 17.4mm, 17.6mm, 17.8mm, 18mm, 18.2mm, 18.4mm, 18.6mm, 18.8mm, 19mm, 19.2mm, 19.4mm, 19.6mm, 19.8mm, 20mm, 20.2mm, 20.4mm, 20.6mm, 20.8mm, 21mm, 21.2mm, 21.4mm, 21.6mm, 21.8mm, 22mm, 22.2mm, 22.4mm, 22.6mm, 22.8mm, or 23mm. The value of S1 is not limited to the listed values; other unlisted values ​​within this range also apply.

[0067] In some embodiments of this application, the tabs 21 are arranged in a trapezoidal shape. That is, the trapezoidal arrangement of the tabs 21 can reduce the weight and space occupied by the tab structure 2 without affecting the firm welding of multiple tabs 21 to each other, thereby improving the energy density of the electrode assembly 1000.

[0068] In some embodiments of this application, the tab 21 includes a first side 3 and a second side 4 disposed opposite to each other in the second direction Z. The first side 3 is located at the junction of the tab 21 and the electrode body 11. The length of the first side 3 in the third direction Y is defined as S2, and the length of the second side 4 in the third direction Y is defined as S3. Wherein, S2 and S3 satisfy: 41mm≤S2≤47mm, 34mm≤S3≤40mm. That is, in this embodiment, S2 and S3 satisfy the range of 41mm≤S2≤47mm, 34mm≤S3≤40mm, to ensure that the multiple tabs 21 in the tab structure 2 can be completely welded together, and the welding range between the multiple tabs 21 is complete and consistent. At the same time, it avoids the situation where the welding area between the multiple tabs 21 is too small, thereby increasing the internal resistance of the electrode assembly 1000. If S2 is less than 41mm or S3 is less than 34mm, there may be a risk that the welding area between multiple tabs 21 is too small, which may lead to an increase in the internal resistance of the electrode assembly 1000. If S2 is greater than 47mm or S3 is greater than 40mm, there may be a risk of short circuit caused by the overlap of the tabs 21 with the cover plate assembly of the battery.

[0069] The values ​​of S2 and S3 are matched to ensure that the tab 21 can be arranged in a trapezoidal shape.

[0070] The value of S2 can be 41mm, 41.2mm, 41.4mm, 41.6mm, 41.8mm, 42mm, 42.2mm, 42.4mm, 42.6mm, 42.8mm, 43mm, 43.2mm, 43.4mm, 43.6mm, 43.8mm, 44mm, 44.2mm, 44.4mm, 44.6mm, 44.8mm, 45mm, 45.2mm, 45.4mm, 45.6mm, 45.8mm, 46mm, 46.2mm, 46.4mm, 46.6mm, 46.8mm, or 47mm. The value of S2 is not limited to the listed values; other unlisted values ​​within this range also apply.

[0071] The value of S3 can be 34mm, 34.2mm, 34.4mm, 34.6mm, 34.8mm, 35mm, 35.2mm, 35.4mm, 35.6mm, 35.8mm, 36mm, 36.2mm, 36.4mm, 36.6mm, 36.8mm, 37mm, 37.2mm, 37.4mm, 37.6mm, 37.8mm, 38mm, 38.2mm, 38.4mm, 38.6mm, 38.8mm, 39mm, 39.2mm, 39.4mm, 39.6mm, 39.8mm, or 40mm. The value of S3 is not limited to the listed values; other unlisted values ​​within this range also apply.

[0072] Please refer to Figure 5. In some embodiments of this application, the shortest distance between the projection of the periphery of one electrode 21 onto the welding surface 5 and the projection of the periphery of the other electrode 21 onto the welding surface 5 is S4; wherein S4 satisfies: 0mm < S4 ≤ 2mm. The orthographic projection of the electrode structure 2 in the first direction Y is trapezoidal. In this embodiment, S4 is designed to satisfy the range of 0mm < S4 ≤ 2mm, so that the height of the trapezoidal orthographic projection of the electrode structure 2 in the first direction Y is maintained between 15mm and 23mm, the length of the upper base in the third direction Y is maintained between 34mm and 40mm, and the length of the lower base in the third direction Y is maintained between 41mm and 47mm. If S4 is greater than 2mm, the overall size of the electrode structure 2 will be too large, leading to a short circuit risk when the electrode 21 is inserted into the electrode structure 1 or when the electrode 21 overlaps with the battery cover assembly.

[0073] Furthermore, in one embodiment of this application, the S4 value can also be 0, that is, at least two tabs 21 have the same size. However, on this basis, it is necessary to ensure that the size of the tab 21 near the welding surface 5 is larger than the size of the tab 21 away from the welding surface 5, and the size of the tab structure 2 in the second direction Z is decreasing, so as to facilitate the tooling fixture in the related technology to clamp multiple tabs 21 together, and ensure that after the tab structure 2 is bent, multiple layers of tabs 21 are welded together during ultrasonic welding, so that the ends of multiple tabs 21 away from the tab structure 2 after bending are basically aligned with each other, and the welding range between multiple tabs 21 is consistent, so as to avoid the risk of missing welding.

[0074] Based on the electrode assembly 1000 in the above embodiments, this application also proposes a battery, which includes at least one electrode assembly 1000 and a cover plate assembly, wherein the cover plate assembly is connected to the tab structure 2 of the electrode assembly 1000. The electrode assembly 1000 is as described in the above embodiments. Since this battery adopts all the technical solutions of all the above embodiments, it at least has the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated further here.

[0075] In some embodiments of this application, the number of electrode assemblies 1000 is set to two, and the two electrode assemblies 1000 are arranged in the first direction Y; the welding surfaces 5 of the two tab structures 2 are respectively connected to the cover plate assembly to reduce the risk of the tabs 21 tearing when the tab structure 2 is bent and to avoid the risk of missing welding between multiple tabs 21.

[0076] It is understood that the size of the tab 21 closer to the welding surface 5 is larger than the size of the tab 21 farther away from the welding surface 5. In this embodiment, in the process of welding multiple tabs 21 to the cover plate assembly of the battery and then inserting the electrode assembly 1000 into the casing, it is necessary to adjust the positional relationship between the electrode assembly 1000 and the cover plate assembly. That is, multiple tabs 21 will be bent. Since the sizes of multiple tabs 21 are different, the size of one or more tabs 21 closer to the welding surface 5 is larger than the size of one or more tabs 21 farther away from the welding surface 5. When multiple tabs 21 are bent, the risk of tabs 21 tearing can be reduced.

[0077] In addition, multiple tabs 21 of different sizes are stacked together to facilitate the tooling fixtures in related technologies to clamp the multiple tabs 21 together, ensuring that after the tab structure 2 is bent, the multiple tabs 21 are welded together during ultrasonic welding, so that the ends of the multiple tabs 21 away from the tab structure 2 after bending are basically aligned with each other, and the welding range between the multiple tabs 21 is consistent, so as to avoid the risk of missing welding.

[0078] The battery in the related technology is a lithium iron phosphate battery and the electrode assembly 1000 is a wound core. The number of turns of the winding is 25 turns for the positive electrode and 26 turns for the negative electrode. The negative electrode has 26 layers and the positive electrode has 25 layers. Therefore, there are 25 positive electrode tabs and 26 negative electrode tabs in one wound core. Based on this, the battery is charged and discharged at the current of its nominal capacity. At this time, the highest temperature of the terminal is 39°C and the temperature of the battery surface is 42°C.

[0079] In one embodiment of this application, the battery is a lithium iron phosphate battery and the electrode assembly 1000 is a winding core. When the number of turns of the winding is 25 turns for the positive electrode and 26 turns for the negative electrode, there are 50 positive electrode tabs and 52 negative electrode tabs in one winding core. At this time, the highest temperature of the electrode post is 36°C and the temperature of the battery surface is 40°C.

[0080] In addition, if the number of positive electrode tabs is between 25 and 50, and the number of negative electrode tabs is between 26 and 52, such as 38 positive electrode tabs and 40 negative electrode tabs, then the highest temperature of the electrode post is between 36°C and 39°C, and the temperature of the battery surface is between 40°C and 42°C.

[0081] Please refer to Figures 6 to 9. Label B indicates a battery with 25 positive tabs and 26 negative tabs in electrode assembly 1000; label C indicates a battery with 50 positive tabs and 52 negative tabs in electrode assembly 1000; and label D indicates a battery with 38 positive tabs and 40 negative tabs in electrode assembly 1000.

[0082] Please refer to Figures 6 and 7. Figure 6 shows the temperature rise of the terminals of B, C, and D when charging at the nominal capacity current. Figure 7 shows the temperature rise of the battery surface when charging at the nominal capacity current.

[0083] Please refer to Figures 8 and 9, which show the relationship between the DC internal resistance (DCR) and the state of charge (SOC) during charging of batteries B, C, and D. Figure 8 shows the DC internal resistance variation curve during battery charging, and Figure 9 shows the DC internal resistance variation curve during battery discharging.

[0084] In summary, as shown in Figures 6 and 7, the more tabs a battery has, the lower its internal resistance. Lower internal resistance means lower voltage drop and lower losses, resulting in higher energy efficiency during charging and discharging. When the internal resistance is low, both the ohmic resistance and polarization resistance decrease, which reduces the heat generated during operation. In other words, the temperature rise of the battery proposed in this embodiment is lower than that of batteries in related technologies, thus effectively reducing the heat generated during operation.

[0085] As shown in Figures 8 and 9, during charging, the internal resistance of the battery increases with the increase of the state of charge; during discharging, the DC internal resistance of the lithium-ion battery increases with the decrease of the state of charge. However, during charging and discharging, the DC internal resistance of the battery proposed in this application is lower than that of batteries in related technologies. Therefore, the DC internal resistance of the battery proposed in this application is lower, thereby effectively reducing the heat generated by the battery during operation.

[0086] Please refer to Figures 10 to 15, which show some other embodiments of the electrode assembly 1000 proposed in this application.

[0087] Please refer to Figures 10 to 13. In some embodiments of this application, the electrode structure 1 includes a wound body 10, which includes a positive electrode 11A, a separator 12, and a negative electrode 13 that are stacked and wound in sequence.

[0088] Multiple tabs 21 are disposed at the axial end of the winding body 10. The multiple tabs 21 are respectively connected to different winding layers of the same electrode sheet and are aligned with each other in a direction parallel to the axial end. The axial direction of the winding body 10 is the height direction of the tabs 21. Along the alignment direction of the multiple tabs 21, the height of the multiple tabs 21 gradually decreases.

[0089] It is understandable that the cross-section of the coil 10 can be circular, elliptical, or a combination of straight lines and arcs.

[0090] Multiple tabs 21 can be combined to form a tab group, that is, the tab group is set at the axial end of the winding body 10.

[0091] The multiple tabs 21 of the tab group are respectively connected to different winding layers of the same electrode sheet, that is, the tabs 21 of the tab group are tabs 21 of the same polarity.

[0092] In this application, the electrode group can be either a positive electrode group 2A or a negative electrode group 5A.

[0093] Among them, the tab 21 in the positive tab group 2A is the positive tab, which is connected to the positive electrode plate 11A.

[0094] The tab 21 in the negative tab group 5A is the negative tab, which is connected to the negative electrode plate 13.

[0095] The positive electrode group 2A and the negative electrode group 5A are two independent electrode groups with their own alignment direction and height.

[0096] The height of tab 21 refers to its dimension along the axial direction of the winding body 10. The width of tab 21 refers to its dimension along the winding direction of the winding body 10.

[0097] Multiple tabs 21 in the tab group are aligned with each other, meaning that the central axis of the multiple tabs 21 is coplanar along their height direction. For example, the height of the multiple tabs 21 gradually decreases, which can be a gradual decrease according to a fixed value or a gradual decrease according to a non-fixed value. It can be that two adjacent tabs gradually decrease, or that the height decreases gradually in groups. For example, along the direction of alignment of the multiple tabs 21, the first 10% of the tabs 21 extend outward from the axial end of the winding body 10 at the same height; the 10% to 30% of the tabs 21 extend outward from the axial end of the winding body 10 at the same height, and are higher than the first 10% of the tabs 21. 1. Smaller; the height of the tabs 21 in the 30% to 50% range extending outward from the axial end of the winding body 10 is consistent and smaller than that of the tabs 21 in the 10% to 30% range; the height of the tabs 21 in the 50% to 80% range extending outward from the axial end of the winding body 10 is consistent and smaller than that of the tabs 21 in the 30% to 50% range; the height of the tabs 21 in the 80% to 100% range extending outward from the axial end of the winding body 10 is consistent and smaller than that of the tabs 21 in the 50% to 80% range.

[0098] In some embodiments of this application, the electrode structure 2 includes an electrode group, which includes a plurality of electrodes 21. The electrode group includes a first electrode group 3A and a second electrode group 4A. The first electrode group 3A and the second electrode group 4A are located at the same axial end of the winding body 10. The first electrode group 3A and the second electrode group 4A are respectively disposed on both sides of the winding axis of the winding body 10 and are aligned with each other.

[0099] It can be understood that the first electrode group 3A and the second electrode group 4A are aligned with each other, meaning that the central axis of the electrode in the height direction of the first electrode group 3A and the central axis of the electrode in the height direction of the second electrode group 4A are coplanar.

[0100] In some embodiments of this application, the number of electrodes in the first electrode group 3A is the same as the number of winding layers of the electrode sheet, and the direction in which the multiple electrodes 21 are aligned is from the second electrode group 4A to the first electrode group 3A.

[0101] It is understandable that the number of tabs 21 in the second tab group 4A can be adjusted as needed, thereby adjusting the current-passing area of ​​the tabs 21 to adapt to the battery requirements of different rates.

[0102] In some embodiments of this application, the winding direction of the winding body 10 is the width direction of the tab 21, and the width of the multiple tabs 21 gradually decreases along the direction in which the multiple tabs 21 are aligned.

[0103] It is understandable that the width of the tabs 21 extending along the winding direction of the winding body 10 gradually decreases. This can be a gradual decrease by a fixed value or a gradual decrease by a non-fixed value. It can be a gradual decrease for two adjacent tabs or a gradual decrease for groups. For example, along the alignment direction of the tabs 21, the width of the first 10% of the tabs 21 extending along the winding direction of the winding body 10 is consistent; the width of the tabs 21 extending along the winding direction of the winding body 10 from the 10% to the 30% is consistent and greater than the previous width. The tabs 21 in the 10% range are smaller; the tabs 21 in the 30% to 50% range have a consistent width along the winding direction of the winding body 10 and are smaller than the tabs 21 in the 10% to 30% range; the tabs 21 in the 50% to 80% range have a consistent width along the winding direction of the winding body 10 and are smaller than the tabs 21 in the 30% to 50% range; the tabs 21 in the 80% to 100% range have a consistent width along the winding direction of the winding body 10 and are smaller than the tabs 21 in the 50% to 80% range.

[0104] In some embodiments of this application, the width of the plurality of tabs 21 gradually decreases along the direction away from the winding body 10.

[0105] It is understood that the shape of the electrode 21 can be trapezoidal, and the inclination of the two sides can be set as needed. In some embodiments of this application, the electrode is an isosceles trapezoid.

[0106] Please refer to Figure 11. In some embodiments of this application, the side of the tab 21 facing away from the electrode is arc-shaped 6. It can be understood that the curvature of the arc-shaped 6 can be set as needed.

[0107] Please refer to Figures 12 and 13. In some embodiments of this application, the two ends of the tab 21 on the side away from the electrode are provided with chamfers 7.

[0108] It is understandable that chamfer 7 can be a rounded corner or a triangular notch, and the size and shape of the triangular notch can be set as needed.

[0109] In one embodiment, the electrode group is a first polarity electrode group, and the electrode assembly 1000 also includes a second polarity electrode group. The second polarity electrode group and the first polarity electrode group are respectively disposed at both ends of the same axial end of the winding body 10. One of the first polarity electrode group and the second polarity electrode group is a positive electrode group 2A, and the other is a negative electrode group 5A.

[0110] In some embodiments of this application, the first polarity tab group is a positive tab group 2A, and the second polarity tab group is a negative tab group 5A. The negative tab group 5A includes multiple negative tabs, which are respectively connected to different winding layers of the negative electrode sheet and are aligned with each other. Along the alignment direction of the multiple negative tabs, the height of the multiple negative tabs gradually decreases.

[0111] It is understood that the tab group in this application is the positive tab group 2A, and the tabs within the positive tab group 2A are the positive tabs, connected to the positive electrode plate 11A. The tabs within the negative tab group 5A are the negative tabs, connected to the negative electrode plate 13. The negative tabs of the negative tab group 5A can also meet the height, width, structure, and other characteristics of the tabs 21 within the tab group (for details, please refer to the description of the tab group above). To keep the specification concise, further details are omitted here.

[0112] Based on the electrode assembly 1000 in the above embodiments, and referring to Figures 10 to 15, this application embodiment also provides a battery, including:

[0113] Connecting piece 8;

[0114] In the aforementioned electrode assembly, the tabs in the tab group are overlapped at the ends opposite to the electrode and welded to the same side of the connecting piece 8.

[0115] It is understood that the tab assembly can be either a positive tab assembly 2A or a negative tab assembly 5A. Correspondingly, the connecting piece 8 can be either a positive connecting piece 81 or a negative connecting piece 82. The positive tabs of the positive tab assembly 2A are welded to the positive connecting piece 81, and the negative tabs of the negative tab assembly 5A are welded to the negative connecting piece 82. The positive tab assembly 2A includes multiple positive tabs. During welding, the ends of the multiple positive tabs facing away from the positive electrode piece 11A are first overlapped together, and then welded to the same surface of the positive connecting piece 81 to avoid incomplete welding. The negative tab assembly 5A includes multiple negative tabs. During welding, the ends of the multiple negative tabs facing away from the negative electrode piece 13 are first overlapped together, and then welded to the same surface of the negative connecting piece 82 to avoid incomplete welding.

[0116] In some embodiments of this application, the battery includes at least two electrode assemblies 1000. In the at least two electrode assemblies 1000, the tabs of adjacent electrode assemblies 1000 are aligned with each other. A connecting piece 8 is welded to the tabs of adjacent electrode assemblies 1000.

[0117] In some embodiments of this application, the connecting piece 8 is a U-shaped connecting piece, including opposing first and second extensions. The first extension is welded to the tab assembly of one of two adjacent electrode assemblies 1000. The second extension is welded to the tab assembly of the other of the two adjacent electrode assemblies 1000.

[0118] In some embodiments of the application, the electrode assembly includes a first electrode assembly 3A and a second electrode assembly 4A. The first electrode assemblies 3A of two adjacent electrode assemblies 1000 are arranged adjacent to each other.

[0119] Please refer to Figures 16 to 25, which show some other embodiments of the electrode assembly 1000 proposed in this application.

[0120] As shown in Figures 16 to 19, this application embodiment provides an electrode assembly 1000, the electrode structure 1 including a main body 110 and electrode tabs 21. The main body 110 is configured to be wound to form a core 20. The main body 110 has a winding start end 130 and a winding end 140. The direction from the winding start end 130 to the winding end end 140 is the winding direction. At least two electrode tabs 21 are provided, and they are spaced apart on one side of the main body 110 along the winding direction. Along the winding direction, the height of the electrode tabs 21 located at odd-numbered positions has an opposite gradient trend to the height of the electrode tabs 21 located at even-numbered positions.

[0121] In this embodiment, the core 20 is formed by winding the main body 110, such that at least two tabs 21 have opposite gradients in height between the odd-numbered tabs and the even-numbered tabs along the winding direction, resulting in slightly different heights for each tab 21. When all tabs 21 are bent and welded to the connecting piece 8, the integrity of the solder joint is ensured, and interference that could cause the tabs 21 to tear is avoided.

[0122] Along the winding direction, the height of the tabs 21 located at odd-numbered positions has an opposite gradual change trend to that of the tabs 21 located at even-numbered positions, including: the height of the tabs 21 located at odd-numbered positions decreases, and the height of the tabs 21 located at even-numbered positions increases. Alternatively, the height of the tabs 21 located at odd-numbered positions increases, and the height of the tabs 21 located at even-numbered positions decreases.

[0123] The height of the tabs 21 located in odd-numbered positions decreases, while the height of the tabs 21 located in even-numbered positions increases. This means that for different odd-numbered tabs 21, the height of each tab 21 decreases; for different even-numbered tabs 21, the height of each tab 21 increases. Alternatively, the height of the tabs 21 located in odd-numbered positions increases, while the height of the tabs 21 located in even-numbered positions decreases. This ensures that all tabs 21 do not interfere after bending and ensures the integrity of the solder joint.

[0124] The height of the tab 21 refers to the distance between the end of the tab 21 furthest from the main body 110 and the end of the tab 21 closest to the main body 110.

[0125] In some embodiments of this application, the tabs 21 can be set to 2n, where n ≥ 1 and n is an integer. The 2n tabs 21 are defined as position tab 1, position tab 2, position tab 3, ..., position tab 2n. Position tab 1 is positioned near the winding start end 130, and position tab 2n is positioned near the winding end end 140. Based on the winding direction being from the winding start end 130 to the winding end end 140, position tab 1 is located in the central region of the core 20, and position tab 2n is located in the edge region of the core 20.

[0126] As shown in Figure 16, in some embodiments of this application, the height of the tabs 21 located at odd-numbered positions decreases, while the height of the tabs 21 located at even-numbered positions increases. Specifically, the height of the tab at position one is less than the height of the tab at position two.

[0127] Understandably, based on the aforementioned height variation pattern, as shown in Figure 17, after the electrode assembly 1000 is wound into the core 20, the height of the tabs 21 can be increased or decreased sequentially. When all the tabs 21 are bent and welded to the connecting piece 8, the integrity of the solder joint can be ensured, and interference that could cause the tabs 21 to tear can be avoided.

[0128] In some embodiments of this application, the electrode assembly 1000 has a wound state. The wound state corresponds to a wound center surface 210. In the wound state, odd-numbered tabs 21 and even-numbered tabs 21 are located on opposite sides of the wound center surface 210, and the projections of all tabs 21 in a first direction at least partially overlap. The first direction is angled to the wound center surface 210.

[0129] It is understood that the electrode assembly 1000 can form a core 20 in the winding state. The formed core 20 has an axisymmetric structure. The winding center plane 210 passes through the axis of symmetry of the core 20 and is the plane of symmetry of the core 20. As shown in Figure 19, when the core 20 is set as a racetrack-shaped core, the winding center plane 210 is parallel to the length direction of the core 20, and the winding center plane 210 is located at the middle position in the width direction of the core 20. Thus, the core 20 can be divided into an upper region and a lower region using the winding center plane 210. As shown in Figure 17, the odd-numbered tabs 21 can be located in the lower region, and the even-numbered tabs 21 can be located in the upper region. In this case, the height of the odd-numbered tabs 21 decreases, and the height of the even-numbered tabs 21 increases. Alternatively, the odd-numbered tabs 21 can also be located in the upper region, and the even-numbered tabs 21 can be located in the lower region. At this point, the height of the odd-numbered electrodes 21 increases, while the height of the even-numbered electrodes 21 decreases.

[0130] In this configuration, the projections of all tabs 21 in the first direction at least partially overlap, so that all tabs 21 can be welded to the same connecting piece 8 after being bent along the first direction. As the electrode assembly 1000 is gradually wound, the size of the resulting core 20 gradually increases. To ensure that the projections of all tabs 21 in the first direction at least partially overlap, the spacing between two adjacent tabs 21 can gradually increase.

[0131] In some embodiments of this application, the projections of all tabs 21 in the first direction completely overlap.

[0132] Based on the fact that tabs 21 are provided on both opposite sides of the winding center surface 210, the core 20 can form a "bi-tab" structure. In related technologies, the core 20 only leads out tabs 21 from one side of the winding center surface 210, forming a "single-tab" structure. In the embodiment of this application, the "bi-tab" structure is completely folded and welded to a connecting piece 8. Compared with the "single-tab" structure, the number of tabs 21 can be doubled, increasing the current-carrying area of ​​the tabs 21 and reducing the battery's internal resistance and temperature rise. At the same time, by combining the height variation pattern of the odd-numbered tabs 21 and the even-numbered tabs 21, the integrity of the battery soldering of the "bi-tab" structure can be ensured, and interference of the tabs 21 during ultrasonic welding can be avoided.

[0133] Taking an example where odd-numbered tabs 21 are located in the lower region and even-numbered tabs 21 are located in the upper region, with the height of odd-numbered tabs 21 decreasing and the height of even-numbered tabs 21 increasing, the uppermost tab 21 has the longest height, and the lowermost tab 21 has the shortest height. When all tabs 21 are bent, this ensures that the uppermost tab 21 has sufficient area for ultrasonic welding, guaranteeing a complete weld. It also prevents the lowermost tab 21 from becoming too long, which could cause bending and / or welding interference.

[0134] As shown in Figures 17 and 19, the first direction is perpendicular to the winding center plane 210. Alternatively, the first direction may be set at an acute or obtuse angle to the winding center plane 210. The first direction can be the thickness direction of the core 20.

[0135] Among them, the electrode assembly 1000 can be wound to form a cylindrical core, a square core, or a racetrack-shaped core.

[0136] In some embodiments of this application, the electrode assembly 1000 is wound into a racetrack-shaped core.

[0137] In some embodiments of this application, in the wound state, all tabs 21 are bent toward a connecting piece 8 and welded to the connecting piece 8. When the tabs 21 are in the bent state, the distance between the free end of the shortest tab 21 and the free end of the longest tab 21 is Y, which satisfies: 0 mm ≤ Y ≤ 1 mm.

[0138] It is understandable that when the tab 21 is in a bent state, ensuring that the free end of the shortest tab 21 and the free end of the longest tab 21 are within a range of less than or equal to 1 mm can guarantee the integrity of the solder mark and avoid interference that could cause the tab 21 to tear.

[0139] It should be noted that after all the tabs 21 are bent, the free end of the shortest tab 21 can extend beyond the free end of the longest tab 21. In this case, the free end of the shortest tab 21 is further away from the main body 110. Alternatively, the free end of the longest tab 21 can extend beyond the free end of the shortest tab 21. In this case, the free end of the longest tab 21 is further away from the main body 110.

[0140] For example, the distance Y between the free end of the shortest tab 21 and the free end of the longest tab 21 is set to 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, or any value between the two.

[0141] In some embodiments of this application, when the tab 21 is in a bent state, the free ends of all tabs 21 are flush.

[0142] Understandably, making the free ends of all tabs 21 flush when they are bent, so that all tabs 21 can be aligned with the connecting piece 8, can improve aesthetics and welding quality.

[0143] Among them, the connecting piece 8 is usually located near the side of the shorter tab 21.

[0144] As shown in Figure 18, in some embodiments of this application, the main body 110 has a proximal end 160 near the connecting piece 8 along the first direction. The distance between the proximal end 160 and the connecting piece 8 is X, satisfying: 1 mm ≤ X ≤ 3 mm.

[0145] Understandably, the selection of the connecting piece 8 position ensures that the free ends of all tabs 21 are flush after bending. If the distance X between the near end 160 and the connecting piece 8 is less than 1 mm, the solder joint may be incomplete due to insufficient length of the uppermost tab 21. If the distance X between the near end 160 and the connecting piece 8 is greater than 3 mm, the lowermost tab 21 may not be able to be soldered to the connecting piece 8.

[0146] For example, the distance X between the proximal end 160 and the connecting piece 8 can be set to 1 mm, 2 mm or 3 mm, or any value between the two.

[0147] Based on the electrode assembly 1000 in the above embodiments, as shown in Figures 20 to 22, an embodiment of this application provides a battery, which includes a housing 30 and a core pack 50. The cover assembly includes a connecting piece 8. The connecting piece 8 includes a positive electrode connecting piece and a negative electrode connecting piece. The positive electrode connecting piece has a positive electrode tab connection portion. The negative electrode connecting piece has a negative electrode tab connection portion. The core pack 50 is disposed within the housing 30. The core pack 50 includes a core 20. The core 20 includes a main body and a separator. The main body includes a positive electrode sheet and a negative electrode sheet, and the main body 110 is as described in the previous embodiments. The positive electrode tabs of the positive electrode sheets are all bent and welded to the positive electrode connecting piece. The negative electrode tabs of the negative electrode sheets are all bent and welded to the negative electrode tab connection portion.

[0148] In this embodiment, the core 20 is formed by winding the main body 110, such that at least two tabs 21 have opposite gradients in height between the odd-numbered tabs and the even-numbered tabs along the winding direction, resulting in slightly different heights for each tab 21. When all tabs 21 are bent and welded to the connecting piece 8, the integrity of the solder joint is ensured, and interference that could cause the tabs 21 to tear is avoided.

[0149] Each housing 30 may contain two core packages 50, which can form a core package pair. The two core packages 50 are then combined and directly placed inside the housing 30. Alternatively, each housing 30 may contain at least two core package pairs, in which case every two corresponding core packages 50 are combined to form a core package pair before being placed separately inside the housing 30.

[0150] In some embodiments of this application, a core pack pair is provided within the housing 30. For the same core pack pair, the two core packs 50 are folded towards each other to complete the core bonding. That is, the tabs 21 of the two cores 20 are bent towards each other.

[0151] The connecting piece 8, acting as a current collector, is welded to all corresponding tabs 21. Specifically, the connecting piece 8 includes a positive connecting piece and a negative connecting piece. The positive tab connection portion of the positive connecting piece is used to weld the positive tab, and the negative tab connection portion of the negative connecting piece is used to weld the negative tab. The positive and negative connecting pieces can be welded to the same housing cover 310 to achieve electrical connection between them. Typically, the tabs 21 are welded to the connecting piece 8 using ultrasonic welding.

[0152] In some embodiments of this application, the positive electrode tab of the positive electrode connector includes two spaced-apart tabs 410. The positive electrode tabs of the positive electrode are all bent and then welded to the tabs 410.

[0153] In some embodiments of this application, the positive electrode connecting piece and the negative electrode connecting piece have the same structure.

[0154] As shown in Figures 16 to 18, in some embodiments of this application, the number of positive electrode tabs is set to 2n. The height of the positive electrode tab at position (2n-1) is the smallest. The height of the positive electrode tab at position 2n is the largest. Furthermore, the height of the first positive electrode tab is less than the height of the second positive electrode tab. Wherein, n ≥ 1, and n is an integer.

[0155] Understandably, by setting the number of tabs 21 to an even number, and minimizing the height of the positive tab at position (2n-1), maximizing the height of the positive tab at position 2n, and ensuring that the height of the first positive tab is less than that of the second positive tab, the height of the positive tabs can sequentially increase or decrease after the positive electrode sheet is wound into the core 20. When all the positive tabs are bent and welded to the positive electrode connecting piece, the integrity of the solder joint can be guaranteed, and interference that could cause tearing of the positive tabs can be avoided.

[0156] The height of the positive electrode tab can vary in an equal gradient, meaning that the heights of all positive electrode tabs are distributed arithmetically. The height difference between the positive electrode tab at position (2n-1) and position 2n, combined with the total number of positive electrode tabs, can be used to calculate the tolerance of the positive electrode tab heights, thus determining the height of all positive electrode tabs.

[0157] In some embodiments of this application, the height of the positive electrode tab at position 2n is positively correlated with the length of the root of the negative electrode tab and the root of the positive electrode tab, the length of the welding area of ​​the positive electrode tab, and the length of the bending area of ​​the positive electrode tab.

[0158] It is understandable that the height of the positive electrode tab at position 2n increases with the sum of the lengths of the roots of the negative and positive electrode tabs, the length of the positive electrode tab welding area, and the length of the positive electrode tab bending area; conversely, it decreases with the decrease of the sum of the lengths of the roots of the negative and positive electrode tabs, the length of the positive electrode tab welding area, and the length of the positive electrode tab bending area. This positive correlation can be linear, exponential, or other similar relationships.

[0159] Based on the design of the above three parameters, the maximum height of the positive electrode tab can be directly calculated, which facilitates the processing and shaping of the positive electrode tab.

[0160] In some embodiments of this application, the height of the positive electrode tab at position 2n is a. The sum of the lengths of the root of the negative electrode tab and the root of the positive electrode tab is 0. The length of the welding area of ​​the positive electrode tab is L1. The length of the bending area of ​​the positive electrode tab is L2. This satisfies: a = L1 + L2 + 0.

[0161] It is understandable that the height of the positive electrode tab at position 2n is linearly related to the sum of the lengths of the root of the negative electrode tab and the root of the positive electrode tab, the length of the welding area of ​​the positive electrode tab, and the length of the bending area of ​​the positive electrode tab. Based on the above relationship, the height of the positive electrode tab at position 2n can be calculated quickly.

[0162] The length of the negative electrode lug root is O1, and the length of the positive electrode lug root is O2. This satisfies the condition: O = O1 + O2. The lengths of the negative and positive electrode lug roots are design parameters of the battery. Based on the battery model, the lengths of the negative and positive electrode lug roots can be directly obtained, thus yielding the sum of their lengths.

[0163] In some embodiments of this application, the length of the positive electrode tab welding area is positively correlated with the width of the solder mark and the width of the connecting lug 410.

[0164] It is understandable that the length of the positive electrode tab welding area increases with the increase of the width of the solder mark and the width of the connecting lug 410, and decreases with the decrease of the width of the solder mark and the width of the connecting lug 410. This positive correlation can be linear, exponential, or other similar relationships.

[0165] In some embodiments of this application, the positive electrode tab is configured to be welded to the connecting ear 410 by at least two rounds of welding processes. The width of the solder mark formed on the positive electrode tab in the last round of welding is W2. The width of the connecting ear 410 is W3. This satisfies: L1 = 0.5(W2 + W3) + k1, where k1 is a first preset allowance.

[0166] Understandably, if there are a large number of positive tabs, at least two rounds of welding processes are required to weld all the tabs 21 to the corresponding connecting lugs 410. The final welding process forms a solder mark with a width of W2 on the topmost positive tab. The length of the positive tab welding area is calculated by combining the width of this solder mark with the width of the connecting lug 410.

[0167] The width of the solder mark and the width of the connector 410 are design parameters of the battery. Based on the battery model, the width of the solder mark and the width of the connector 410 can be directly obtained, thus determining the length of the positive electrode tab welding area.

[0168] In some embodiments of this application, the following condition is satisfied: 1 ≤ k1 ≤ 2. For example, the first preset margin k1 is set to 1, 1.5, 2, or any value between the two.

[0169] In some embodiments of this application, the positive electrode tab is raised by a soldering socket and then welded to the corresponding connecting ear 410. The length of the bending area of ​​the positive electrode tab is positively correlated with the distance between the two core packages 50 before they are joined together and the thickness of a single core package 50, and negatively correlated with the width of the positive electrode connecting piece, the height of the soldering socket, and the total thickness of all positive electrode tabs welded to the same connecting ear 410.

[0170] Understandably, to facilitate the welding of the positive electrode tab, the height of the positive electrode tab is raised by the welding socket, and then the positive electrode tab is bent towards the connecting ear 410 and ultrasonically welded. Based on the above relationship, the length of the bending area of ​​the positive electrode tab increases with the increase of the distance between the two core packages 50 before they are joined together and the thickness of a single core package 50, and decreases with the decrease of the distance between the two core packages 50 before they are joined together and the thickness of a single core package 50. It also decreases with the increase of the width of the positive electrode connecting piece, the height of the welding socket, and the total thickness of all positive electrode tabs welded to the same connecting ear 410, and increases with the decrease of the width of the positive electrode connecting piece, the height of the welding socket, and the total thickness of all positive electrode tabs welded to the same connecting ear 410. This positive and negative correlation can be linear, exponential, etc.

[0171] In some embodiments of this application, the distance between the two core packages 50 before they are joined is H3. The thickness of a single core package 50 is T0. The width of the positive electrode connector is W1. The height of the raised solder pad is H0. The total thickness of all positive electrode tabs soldered to the same connector 410 is H4. The following conditions are met:

[0172] .

[0173] Understandably, after all the positive electrode tabs are bent to align their free ends and welded to the positive electrode connecting piece, the bent area of ​​the positive electrode tab is usually an inclined surface. As shown in Figure 20, before the core package 50 is assembled into the housing 30, one end of the bent area of ​​the positive electrode tab is connected to the core package 50, and the other end is connected to the positive electrode connecting piece, so that the inclined surface, the surface of the core package 50, and the line connecting the positive electrode connecting piece to the core package 50 form a right-angled triangle. The length of one right-angled side can be obtained by using the difference between the spacing of the core package 50 before core assembly and the width of the positive electrode connecting piece. The length of the other right-angled side can be obtained by using the difference between the thickness of a single core package 50, the height of the welding seat, and the total thickness of all positive electrode tabs welded to the same connecting piece 410. Thus, the length of the inclined surface is obtained, thereby reflecting the length of the bent area of ​​the positive electrode tab.

[0174] The thickness of a single core pack 50, the width of the positive electrode connector, and the height of the solder pad are all design parameters. Based on the battery model, the thickness of a single core pack 50, the width of the positive electrode connector, and the height of the solder pad can be directly obtained. Combined with the distance between the two core packs 50 before they are joined together, the length of the positive electrode tab bending area can be calculated.

[0175] In some embodiments of this application, the height of the positive electrode tab at position (2n-1) is positively correlated with the sum of the lengths of the root of the negative electrode tab and the root of the positive electrode tab, the distance between the two core packages 50 before they are joined, the width of the solder mark, and the width of the connecting tab 410, and negatively correlated with the width of the positive electrode connecting piece.

[0176] It is understandable that the height of the positive electrode tab at position (2n-1) increases with the sum of the lengths of the roots of the negative and positive electrode tabs of the diaphragm, the distance between the two core packages 50 before they are joined, the width of the solder mark, and the width of the connecting tab 410; it decreases with the sum of the lengths of the roots of the negative and positive electrode tabs of the diaphragm, the distance between the two core packages 50 before they are joined, the width of the solder mark, and the width of the connecting tab 410; it decreases with the increase of the width of the positive electrode connecting piece; and it increases with the decrease of the width of the positive electrode connecting piece. This positive and negative correlation can be linear, exponential, etc.

[0177] Based on the design of the above four parameters, the minimum height of the positive electrode tab can be directly calculated, which facilitates the processing and shaping of the positive electrode tab.

[0178] As shown in Figures 20 and 21, in some embodiments of this application, the height of the positive electrode tab at position (2n-1) is b. The distance between the two core packages 50 before they are joined is H3. The width of the positive electrode connecting piece is W1. The width of the solder mark is W2. The width of the connecting tab 410 is W3. The sum of the lengths of the roots of the negative electrode tab and the positive electrode tab of the diaphragm is 0. This satisfies: b = 0.5(H3-W1) + 0.5(W2+W3) + 0 + k2. Wherein, k2 is the second preset margin.

[0179] It is understandable that the height of the positive electrode tab at position (2n-1) is linearly related to the length of the root of the negative electrode tab and the root of the positive electrode tab, the distance between the two core packages 50 before they are joined, the width of the solder mark, the width of the connecting tab 410, and the width of the positive electrode connecting piece. Based on the above relationship, the height of the positive electrode tab at position (2n-1) can be quickly calculated.

[0180] The lengths of the negative and positive electrode roots of the separator, the width of the solder mark, the width of the connecting lug 410, and the width of the positive electrode connecting piece are all design parameters of the battery. Based on the battery model, the lengths of the negative and positive electrode roots of the separator, the width of the solder mark, the width of the connecting lug 410, and the width of the positive electrode connecting piece can be directly obtained, thus determining the height of the positive electrode lug at position (2n-1).

[0181] In some embodiments of this application, the following condition is satisfied: 1 ≤ k2 ≤ 2. For example, the second preset margin k2 is set to 1, 1.5, 2, or any value between the two.

[0182] In some embodiments of this application, the distance between the two core packages 50 before they are joined together is positively correlated with the distance between the positive electrode connecting piece and the main body 110 and the distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30.

[0183] It is understandable that the distance between the two core packages 50 before they are joined increases with the increase of the distance between the positive electrode connecting piece and the main body 110 and the distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30, and decreases with the decrease of the distance between the positive electrode connecting piece and the main body 110 and the distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30. This positive correlation can be a linear or exponential relationship.

[0184] In some embodiments of this application, the distance between the two core packages 50 before they are joined is H3. The distance between the positive electrode connecting piece and the main body 110 is D1. The distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30 is D2. This satisfies:

[0185] .

[0186] Understandably, based on the above formula, the distance between the two cell packs before they are joined together can be directly obtained from the battery's design parameters. After obtaining the distance between the two cell packs before they are joined together, the maximum and minimum heights of the positive electrode tab can be obtained based on the aforementioned formula.

[0187] The distance between the positive electrode connecting piece and the main body 110 refers to the distance between the positive electrode connecting piece and the main body 110 when the two core packages 50 are in the closed state. The distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30 refers to the distance between the end of the positive electrode connecting piece near the inner wall of the housing 30 and the inner wall of the housing 30 after the two core packages 50 are in the closed state and installed in the housing 30.

[0188] In some embodiments of this application, the housing 30 is connected to a cover 310. The distance between the positive electrode connecting piece and the main body 110 is positively correlated with the height of the housing 30 and the amount of diaphragm compression, and negatively correlated with the distance between the positive electrode connecting piece and the cover 310, the thickness of the positive electrode connecting piece, the total thickness of all positive electrode tabs welded to the same connecting lug 410, and the distance between the diaphragm and the lower surface of the housing 30.

[0189] It is understandable that the distance between the positive electrode connecting piece and the main body 110 increases with the increase of the height of the housing 30 and the amount of diaphragm compression, and decreases with the decrease of the height of the housing 30 and the amount of diaphragm compression. It decreases with the increase of the distance between the positive electrode connecting piece and the housing cover 310, the thickness of the positive electrode connecting piece, the total thickness of all positive electrode ears welded to the same connecting ear 410, and the distance between the diaphragm and the lower surface of the housing 30. It increases with the decrease of the distance between the positive electrode connecting piece and the housing cover 310, the thickness of the positive electrode connecting piece, the total thickness of all positive electrode ears welded to the same connecting ear 410, and the distance between the diaphragm and the lower surface of the housing 30.

[0190] In some embodiments of this application, the height of the housing 30 is H10. The diaphragm compression is k3. The distance from the positive electrode connecting piece to the housing cover 310 is H6. The thickness of the positive electrode connecting piece is H7. The total thickness of all positive electrode tabs welded to the same connecting lug 410 is H4. The distance between the diaphragm and the lower surface of the housing 30 is H9. This satisfies: D1 = H10 - H6 - H7 - H4 - (H9 - k3).

[0191] The height of the casing 30, the diaphragm compression, the distance between the positive electrode connecting piece and the casing cover 310, the thickness of the positive electrode connecting piece, the total thickness of all positive electrode tabs welded to the same connecting lug 410, and the distance between the diaphragm and the lower surface of the casing 30 are all design parameters. Based on the battery model, the height of the casing 30, the diaphragm compression, the distance between the positive electrode connecting piece and the casing cover 310, the thickness of the positive electrode connecting piece, the total thickness of all positive electrode tabs welded to the same connecting lug 410, and the distance between the diaphragm and the lower surface of the casing 30 can be directly obtained, and the distance between the positive electrode connecting piece and the main body 110 can be calculated based on the above formula.

[0192] In some embodiments of this application, the diaphragm compression satisfies the following range: 1.5≤k3≤2.5.

[0193] For example, the diaphragm compression amount k3 can be set to 1.5, 2, 2.5, or any value between the two. The value of the diaphragm compression amount k3 can be selected based on production experience and the battery model.

[0194] In some embodiments of this application, the total thickness of the two core packages 50 is W6. The width of the shell 30 is W5. This satisfies: 0.5(W6-W1)≤D2≤0.5(W5-W1).

[0195] It is understandable that when the two core packages 50 are joined and assembled into the housing 30, if the edge of the core package 50 is in contact with the inner surface of the housing 30, the distance between the edge of the positive electrode connector and the inner wall of the housing 30 is exactly equal to half the difference between the total thickness of the two core packages 50 and the width of the positive electrode connector. If the edge of the core package 50 is spaced apart from the inner surface of the housing 30, the distance between the edge of the positive electrode connector and the inner wall of the housing 30 can be equal to half the difference between the width of the housing 30 and the width of the positive electrode connector. Therefore, the range of the distance between the edge of the positive electrode connector and the inner wall of the housing 30 can be defined based on this relationship, and any value can be taken within this range.

[0196] In some embodiments of this application, the distance between the positive electrode connecting piece and the main body 110 has a maximum value and a minimum value, D1max and D1min, respectively. The distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30 has a maximum value and a minimum value, D2max and D2min, respectively. Wherein, D1max = H10 - H6 - H7 - H4 - (H9 - 2.5), D1min = H10 - H6 - H7 - H4 - (H9 - 1.5), D2max = 0.5(W5 - W1), D2min = 0.5(W6 - W1). This satisfies:

[0197] .

[0198] It is understandable that the value of the diaphragm compression k3 and the range of distance between the edge of the positive electrode connecting piece and the inner wall of the housing 30 will affect the distance between the two core packs 50 before they are joined together. Therefore, the distance range between the two core packs 50 before they are joined together can be calculated first, and a reasonable value can be selected within this range to ensure that the two core packs 50 meet the joining requirements and that the joined core packs 50 can be assembled into the housing 30 and removed from the housing 30.

[0199] H3 cannot be equal to the minimum value calculated using D1min and D2min, in order to prevent the core package 50 from being completely adhered to the inner surface of the housing 30, which would prevent the core package 50 from being removed.

[0200] In some embodiments of this application, the number of negative tabs is set to (2n+2). The negative tab at position (2n+1) has the smallest height. The negative tab at position (2n+2) has the largest height. The height of the first negative tab is less than the height of the second negative tab. The height of the negative tab at position (2n+2) is the same as the height of the positive tab at position 2n.

[0201] Understandably, by ensuring that each negative electrode tab satisfies the aforementioned relationship, the height of the negative electrode tabs can increase or decrease sequentially after the negative electrode sheet is wound into core 20. When all negative electrode tabs are bent and welded to the negative electrode connecting piece, the integrity of the solder joint can be guaranteed, and interference that could cause tearing of the negative electrode tabs can be avoided. Having two more negative electrode tabs than positive electrode tabs, making the height of the negative electrode tab at position (2n+2) the same as the height of the positive electrode tab at position 2n, eliminates the need to repeatedly calculate the maximum height of the negative electrode tabs, facilitating rapid manufacturing of the negative electrode tabs.

[0202] In some embodiments of this application, the height of the negative electrode tab at position (2n+1) can be equal to the height of the positive electrode tab at position (2n-1). In this case, the minimum height calculated for the positive electrode tab can be directly used as the minimum height of the negative electrode tab. Based on the minimum height, maximum height, and number of negative electrode tabs, the height tolerance can be calculated, and then the length of all negative electrode tabs can be calculated based on this tolerance.

[0203] In some embodiments of this application, the height of the negative electrode tab at position (2n-1) can be equal to the height of the positive electrode tab at position (2n-1). In this case, the minimum height calculated among the positive electrodes can be directly used as the height of the negative electrode tab at position (2n-1). Based on the negative electrode tab at position (2n-1), the maximum height of the negative electrodes, and the number of negative electrodes, the height tolerance can be calculated, and then the length of all negative electrodes can be calculated based on this tolerance.

[0204] Based on the batteries in the above embodiments, embodiments of this application provide a battery pack including the batteries as described above.

[0205] In this embodiment, the core 20 is formed by winding the main body 110, such that at least two tabs 21 have opposite gradients in height between the odd-numbered tabs and the even-numbered tabs along the winding direction, resulting in slightly different heights for each tab 21. When all tabs 21 are bent and welded to the connecting piece 8, the integrity of the solder joint is ensured, and interference that could cause the tabs 21 to tear is avoided.

[0206] As shown in Figure 23, an embodiment of this application provides a design method for an electrode assembly 1000, applied to a battery as described above. The method includes:

[0207] S810: Based on the battery design parameters, obtain the maximum height and minimum height of tab 21.

[0208] S820, along the winding direction, the height of the tabs 21 located at odd positions has a opposite gradient trend to the height of the tabs 21 located at even positions, and the projections of all tabs 21 welded to the tab connection portion of the same connecting piece 8 in the same core 20 in the first direction at least partially overlap.

[0209] Based on the aforementioned height variation pattern, after the electrode assembly 1000 is wound into the core 20, the height of the tabs 21 can be increased or decreased sequentially. When all the tabs 21 are bent and welded to the connecting piece 8, the integrity of the solder joint can be guaranteed, and interference that could cause the tabs 21 to tear can be avoided.

[0210] The electrode assembly 1000 can form a core 20 in a wound state. The formed core 20 has an axisymmetric structure. The winding center plane 210 passes through the axis of symmetry of the core 20. Thus, the core 20 can be divided into an upper region and a lower region using the winding center plane 210. As shown in Figure 17, the odd-numbered tabs 21 can be located in the lower region, and the even-numbered tabs 21 can be located in the upper region. In this case, the height of the odd-numbered tabs 21 decreases, and the height of the even-numbered tabs 21 increases. Alternatively, the odd-numbered tabs 21 can be located in the upper region, and the even-numbered tabs 21 can be located in the lower region. In this case, the height of the odd-numbered tabs 21 increases, and the height of the even-numbered tabs 21 decreases.

[0211] In this process, the projections of all tabs 21 welded to the tab connection portion of the same core 20 in the first direction at least partially overlap, so that all tabs 21 can be welded to the same connection portion 8 after being bent along the first direction. As the electrode assembly 1000 is gradually wound, the size of the formed core 20 gradually increases. To ensure that the projections of all tabs 21 welded to the tab connection portion of the same connection portion 8 in the first direction at least partially overlap, the spacing between two adjacent tabs 21 can gradually increase.

[0212] In some embodiments of this application, the projections of all tabs 21 welded to the tab connection portion of the same connecting piece 8 in the first direction completely overlap.

[0213] Since tabs 21 are provided on both sides of the winding center surface 210, the winding core 20 can form a "bi-tab" structure. In related technologies, tabs 21 are only led out from one side of the winding center surface 210, which is a "single-tab" structure. In the embodiment of this application, the "bi-tab" structure is completely folded and welded to a connecting piece 8, which can double the number of tabs 21, increase the current-passing area of ​​the tabs 21, and reduce the internal resistance and temperature rise of the battery. Furthermore, by combining the height variation pattern of the odd-numbered tabs 21 and the even-numbered tabs 21, the integrity and newness of the "bi-tab" battery soldering can be ensured, and interference during the welding of the tabs 21 can be avoided.

[0214] Along the winding direction, the height of the tabs 21 located at odd-numbered positions has an opposite gradual change trend to that of the tabs 21 located at even-numbered positions, including: the height of the tabs 21 located at odd-numbered positions decreases, and the height of the tabs 21 located at even-numbered positions increases. Alternatively, the height of the tabs 21 located at odd-numbered positions increases, and the height of the tabs 21 located at even-numbered positions decreases.

[0215] The height of the tabs 21 located in odd-numbered positions decreases, while the height of the tabs 21 located in even-numbered positions increases. This means that for different odd-numbered tabs 21, the height of each tab 21 decreases; and for different even-numbered tabs 21, the height of each tab 21 increases. Alternatively, the height of the tabs 21 located in odd-numbered positions increases, while the height of the tabs 21 located in even-numbered positions decreases. This ensures that all tabs 21 welded to the tab connection portion of the same connecting piece 8 do not interfere after bending and ensures the integrity of the solder joint.

[0216] The height of the tab 21 refers to the distance from the end of the tab 21 away from the main body 110 to the main body 110.

[0217] Taking an example where odd-numbered tabs 21 are located in the lower region and even-numbered tabs 21 are located in the upper region, with the height of odd-numbered tabs 21 decreasing and the height of even-numbered tabs 21 increasing, the uppermost tab 21 has the longest height, and the lowermost tab 21 has the shortest height. When bending all the tabs 21 welded to the same connecting lug 410, it ensures that the uppermost tab 21 has sufficient area for ultrasonic welding, ensuring a complete weld. It also prevents the lowermost tab 21 from being too long, thus avoiding bending and / or welding interference.

[0218] As shown in Figure 24, in some embodiments of this application, the battery design parameters include a first design parameter and a second design parameter. At least two core packs 50 are configured, and two core packs 50 form a core pack pair. Based on the battery design parameters, the maximum height and minimum height of the tab 21 are obtained, including:

[0219] S910: Based on the first design parameters, obtain the distance between the two core packages before they are 50 units apart.

[0220] S920, based on the second design parameters and the spacing between the two core packages 50 before they are combined, obtains the maximum height and minimum height of the tab 21.

[0221] Understandably, the distance between the two cell packs 50 before they are joined is first calculated using the battery's first design parameters. Then, using the battery's second design parameters and the distance between the two cell packs 50 before they are joined, the maximum and minimum heights of the tab 21 are calculated. This determines the maximum and minimum heights of the tab 21 in the electrode assembly 1000.

[0222] In some embodiments of this application, the electrode connection portion includes two spaced-apart connecting ears 410, and the electrode 21 is bent and welded to the connecting ears 410. The first design parameters include: the height of the housing 30, the diaphragm compression amount, the distance between the connecting piece 8 and the housing cover 310, the thickness of the connecting piece 8, the total thickness of all electrode ears 21 welded to the same connecting ear 410, the distance between the diaphragm and the lower surface of the housing 30, the total thickness of the two core packages 50, and the width of the housing 30.

[0223] Understandably, based on the battery model, the above parameters are all known constants. Therefore, the distance between the two cell packs before they are joined together can be quickly calculated based on these parameters.

[0224] As shown in Figure 25, in some embodiments of this application, the distance between the two core packages 50 before core bonding is obtained based on the first design parameters, including:

[0225] Based on S1010, the height H10 of the housing 30, the diaphragm compression k3, the distance H6 between the connecting piece 8 and the cover 310, the thickness H7 of the connecting piece 8, the total thickness H4 of all the tabs 21 welded to the same connecting lug 410, and the distance H9 between the diaphragm and the lower surface of the housing 30, the distance D1 between the connecting piece 8 and the main body 110 is obtained, wherein the following relationship is satisfied:

[0226] D1 = H10 - H6 - H7 - H4 - (H9 - k3).

[0227] Based on the battery model, the height of the housing 30, the amount of diaphragm compression, the distance between the connecting piece 8 and the housing cover 310, the thickness of the connecting piece 8, the total thickness of all the tabs 21 welded to the same connecting lug 410, and the distance between the diaphragm and the lower surface of the housing 30 can be directly obtained, and the distance between the connecting piece 8 and the main body 110 can be calculated based on the above formula.

[0228] In some embodiments of this application, the diaphragm compression satisfies the following range: 1.5≤k3≤2.5.

[0229] For example, the diaphragm compression amount k3 can be set to 1.5, 2, 2.5, or any value between the two. The value of the diaphragm compression amount k3 can be selected based on production experience and the battery model.

[0230] S1020. Based on the total thickness W6 of the two core packages 50, the width W5 of the housing 30, and the width W1 of the connecting piece 8, obtain the distance D2 between the edge of the connecting piece 8 and the inner wall of the housing 30, wherein the following relationship is satisfied:

[0231] 0.5(W6-W1)≤D2≤0.5(W5-W1).

[0232] It is understandable that when the two core packages 50 are joined and assembled into the housing 30, if the edge of the core package 50 is in contact with the inner surface of the housing 30, the distance between the edge of the connecting piece 8 and the inner wall of the housing 30 is exactly equal to half the difference between the total thickness of the two core packages 50 and the width of the connecting piece 8; if the edge of the core package 50 is spaced apart from the inner surface of the housing 30, the distance between the edge of the connecting piece 8 and the inner wall of the housing 30 can be equal to half the difference between the width of the housing 30 and the width of the connecting piece 8. Therefore, the range of the distance between the edge of the connecting piece 8 and the inner wall of the housing 30 can be defined based on this relationship, and any value can be taken within this range.

[0233] S1030. Based on the distance D1 between the connecting piece 8 and the main body 110 and the distance D2 between the edge of the connecting piece 8 and the inner wall of the housing 30, the distance H3 before the two core packages 50 are joined together is obtained, wherein the following relationship is satisfied:

[0234] .

[0235] Understandably, based on the above formula, the distance between the two cell packs 50 before they are joined together can be directly obtained from the battery's design parameters. After obtaining the distance between the two cell packs 50 before they are joined together, the maximum and minimum heights of the tab 21 can be obtained based on the aforementioned formula.

[0236] The distance between the connecting piece 8 and the main body 110 refers to the distance between the connecting piece 8 and the main body 110 when the two core packages 50 are in the closed state. The distance between the edge of the connecting piece 8 and the inner wall of the housing 30 refers to the distance between the end of the connecting piece 8 closest to the inner wall of the housing 30 and the inner wall of the housing 30 after the two core packages 50 are in the closed state and installed on the housing 30.

[0237] In some embodiments of this application, the distance between the connecting piece 8 and the main body 110 has a maximum value and a minimum value, namely D1max and D1min. The distance between the edge of the connecting piece 8 and the inner wall of the housing 30 has a maximum value and a minimum value, namely D2max and D2min. Wherein, D1max = H10 - H6 - H7 - H4 - (H9 - 2.5), D1min = H10 - H6 - H7 - H4 - (H9 - 1.5), D2max = 0.5(W5 - W1), D2min = 0.5(W6 - W1), satisfying the following relationship:

[0238] .

[0239] It is understandable that the value of the diaphragm compression k3 and the range of distance between the edge of the connecting piece 8 and the inner wall of the housing 30 will affect the distance between the two core packages 50 before they are joined together. Therefore, the range of distance between the two core packages 50 before they are joined together can be calculated first, and a reasonable value can be selected within this range to ensure that the two core packages 50 meet the joining requirements and that the joined core packages 50 can be assembled into the housing 30 and removed from the housing 30.

[0240] H3 cannot be equal to the minimum value calculated using D1min and D2min, in order to prevent the core package 50 from being completely adhered to the inner surface of the housing 30, which would prevent the core package 50 from being removed.

[0241] In some embodiments of this application, the second design parameters include: the sum of the lengths of the negative electrode ear root and the positive electrode ear root of the diaphragm, the width of the solder mark, the width of the connecting ear 410, the first preset allowance, the second preset allowance, the width of the connecting piece 8, the thickness of the single core package 50, and the height of the solder pad.

[0242] It is understandable that, based on the battery model, the above parameters are all known constants. Therefore, the maximum height and minimum height of tab 21 can be quickly calculated based on these parameters.

[0243] As shown in Figure 26, in some embodiments of this application, based on the second design parameters and the spacing between the two core packages 50 before they are joined, the maximum height and minimum height of the tab 21 are obtained, including:

[0244] S1110, based on the width W2 of the solder mark, the width W3 of the connecting lug 410, and the first preset allowance k1, obtain the length L1 of the positive electrode lug welding area, wherein the following relationship is satisfied:

[0245] L1 = 0.5(W2 + W3) + k1.

[0246] The width W2 of the solder mark refers to the width of the solder mark formed on the tab 21 in the last round of welding. It is understandable that if there are many tabs 21, at least two rounds of welding are required to weld all the tabs 21 to their corresponding connecting ears 410. The last round of welding can form a solder mark with a width of W2 on the uppermost tab 21. The length of the positive tab welding area is calculated by combining the width of this solder mark with the width of the connecting ear 410.

[0247] In some embodiments of this application, the following condition is satisfied: 1 ≤ k1 ≤ 2. For example, the first preset margin k1 is set to 1, 1.5, 2, or any value between the two.

[0248] S1120. Based on the spacing H3 between the two core packages 50 before they are joined together, the width W1 of the connecting piece 8, the thickness T0 of a single core package 50, and the height H4 of the solder pad, the length L2 of the positive electrode tab bending area is obtained, where the following relationship is satisfied:

[0249] .

[0250] Understandably, after all the tabs 21 welded to the same connecting lug 410 are bent to align their free ends and welded to the connecting piece 8, the bent area of ​​the positive tab is typically an inclined surface. As shown in Figure 20, before the core package 50 is assembled into the housing 30, one end of the bent area of ​​the positive tab is connected to the core package 50, and the other end is connected to the connecting piece 8, so that the inclined surface, the surface of the core package 50, and the line connecting the connecting piece 8 to the core package 50 form a right-angled triangle. The length of one right-angled side can be obtained by using the difference between the spacing of the core package 50 before core assembly and the width of the connecting piece 8. The length of the other right-angled side can be obtained by using the difference between the thickness of a single core package 50, the height of the welding seat, and the total thickness of all the tabs 21 welded to the same connecting lug 410. Thus, the length of the inclined surface is obtained, thereby reflecting the length of the bent area of ​​the positive tab.

[0251] S1130. Based on the lengths O of the negative electrode root and the positive electrode root of the diaphragm, the length L1 of the positive electrode welding area, and the length L2 of the positive electrode bending area, the maximum height a of the electrode 21 is obtained, where the following relationship is satisfied:

[0252] a = L1 + L2 + O.

[0253] The length of the negative electrode lug root is O1, and the length of the positive electrode lug root is O2. This satisfies the condition: O = O1 + O2. The lengths of the negative and positive electrode lug roots are design parameters of the battery. Based on the battery model, the lengths of the negative and positive electrode lug roots can be directly obtained, thus yielding the sum of their lengths.

[0254] In some embodiments of this application, based on the second design parameters and the spacing between the two core packages 50 before they are joined, the maximum height and minimum height of the tab 21 are obtained, further including:

[0255] Based on the lengths O of the negative and positive electrode roots of the diaphragm, the distance H3 between the two core packages 50 before they are joined, the width W1 of the connecting piece 8, the width W2 of the solder mark, the width W3 of the connecting ear 410, and the second preset allowance k2, the minimum height b of the electrode ear 21 is obtained, where the following relationship is satisfied:

[0256] b=0.5(H3-W1)+0.5(W2+W3)+O+k2.

[0257] It is understandable that the height of the positive electrode tab at position (2n-1) is linearly related to the length of the root of the negative electrode tab and the root of the positive electrode tab, the distance between the two core packages 50 before they are joined, the width of the solder mark, the width of the connecting ear 410, and the width of the connecting piece 8. Based on the above relationship, the height of the positive electrode tab at position (2n-1) can be quickly calculated.

[0258] The lengths of the base of the negative and positive electrode tabs of the separator, the width of the solder mark, the width of the connecting tab 410, and the width of the connecting piece 8 are all design parameters of the battery. Based on the battery model, the lengths of the base of the negative and positive electrode tabs of the separator, the width of the solder mark, the width of the connecting tab 410, and the width of the connecting piece 8 can be directly obtained, thus determining the height of the positive electrode tab at position (2n-1).

[0259] In some embodiments of this application, the following condition is satisfied: 1 ≤ k2 ≤ 2. For example, the second preset margin k2 is set to 1, 1.5, 2, or any value between the two.

[0260] In some embodiments of this application, along the winding direction, the height of the tabs 21 located at odd-numbered positions has a opposite gradient trend to the height of the tabs 21 located at even-numbered positions, and the projections of all tabs 21 welded to the tab connection portion of the same core 20 in the first direction at least partially overlap, including:

[0261] Along the winding direction, the height of the tabs 21 located at odd positions is set to decrease and the height of the tabs 21 located at even positions is set to increase, and the projections of all tabs 21 welded to the same connecting ear 410 in the same core 20 in the first direction at least partially overlap.

[0262] Understandably, based on the aforementioned height variation pattern, when the electrode assembly 1000 is wound into the core 20, the height of the tabs 21 can be increased or decreased sequentially. When all the tabs 21 welded to the same connecting lug 410 are bent and welded to the connecting piece 8, the integrity of the solder joint can be guaranteed, and interference that could cause the tabs 21 to tear can be avoided.

[0263] In some embodiments of this application, along the winding direction, the height of the odd-numbered tabs 21 decreases and the height of the even-numbered tabs 21 increases, and the projections of all tabs 21 welded to the same connecting piece on the same core 20 in the first direction at least partially overlap, including:

[0264] Based on the number of tabs 21, the maximum height of tabs 21, and the minimum height of tabs 21, the tolerance for the height variation of tabs 21 is obtained.

[0265] Along the winding direction, the height of the tabs 21 located at odd-numbered positions is set to decrease by a tolerance value, and the height of the tabs 21 located at even-numbered positions is set to increase by a tolerance value, so that the height of the first tab is less than the height of the second tab, and the projections of all tabs 21 welded to the same connecting ear 410 in the same core 20 in the first direction at least partially overlap.

[0266] Understandably, based on the maximum and minimum heights of the tab 21, and considering the number of tabs 21, the tolerance for the height variation of the tab 21 is calculated. Based on this tolerance, the height of all tabs 21 can be calculated to facilitate the processing of the tabs 21.

Claims

1. An electrode assembly (1000), comprising: an electrode tab structure (1); and at least one electrode lug structure (2) comprising a plurality of electrode lugs (21), each of the plurality of electrode lugs (21) being arranged on one side of the electrode tab structure (1) and connected to the electrode tab structure (1); wherein a size of at least two adjacent electrode lugs (21) is different. The electrode tab structure (1) comprises a plurality of electrode tab bodies (11) stacked along a first direction, each of the electrode tab bodies (11) comprising a connection end (10) in a second direction intersecting the first direction; 2. The electrode assembly (1000) of claim 1, wherein, each of the electrode lugs (21) is connected to the connection end (10) of a corresponding electrode tab body (11) and extends along the second direction; wherein a size of at least two adjacent electrode lugs (21) is different. In two adjacent electrode lugs (21), a projection of one of the electrode lugs (21) in the first direction completely falls on the other electrode lug (21).

3. The electrode assembly (1000) of claim 2, wherein, The electrode lug structure (2) comprises a welding surface (5) in the first direction, the welding surface (5) being configured to be welded to an output electrode; 4. The electrode assembly (1000) of claim 3, wherein, wherein a size of the electrode lug (21) close to the welding surface (5) is greater than a size of the electrode lug (21) away from the welding surface (5). In the first direction, sizes of the plurality of electrode lugs (21) in the second direction decrease successively.

5. The electrode assembly (1000) of claim 4, wherein, In two adjacent electrode lugs (21), a projection of a periphery of one of the electrode lugs (21) on the welding surface (5) to a projection of a periphery of the other electrode lug (21) on the welding surface (5) has a shortest distance S4; wherein the S4 satisfies: 0mm≤S4≤2mm.

6. The electrode assembly (1000) of claim 4, wherein, A length of the electrode lug (21) in the second direction is defined as S1; wherein the S1 satisfies: 15mm≤S1≤23mm.

7. The electrode assembly (1000) according to any one of claims 1 to 5, wherein, The electrode lug (21) is arranged in a trapezoidal shape.

8. The electrode assembly (1000) according to any one of claims 1 to 5, wherein, The electrode lug (21) comprises a first edge (3) and a second edge (4) oppositely arranged in the second direction, the first edge (3) being located at an interface between the electrode lug (21) and the electrode tab body (11); 9. The electrode assembly (1000) of claim 8, wherein, a length of the first edge (3) in a third direction is defined as S2, a length of the second edge (4) in the third direction is defined as S3, the first direction and the second direction are perpendicular to the third direction; wherein the S2 and the S3 satisfy: 41mm≤S2≤47mm, 34mm≤S3≤40mm. comprising:

10. The electrode assembly (1000) of claim 1, wherein, The electrode tab structure (1) comprises a winding body (10) comprising a positive electrode tab (11A), a separator (12) and a negative electrode tab (13) successively stacked and wound; a plurality of the electrode lugs (21) are arranged at an axial end of the winding body (10), a plurality of the plurality of electrode lugs (21) are respectively connected to different winding layers of the same electrode tab and are arranged in alignment with each other, an axial direction of the winding body (10) is a height direction of the electrode lugs (21), in a direction in which the plurality of electrode lugs (21) are aligned, heights of the plurality of electrode lugs (21) gradually decrease. ​ 11. The electrode assembly (1000) of claim 10, wherein, The tab structure (2) further comprises a tab group comprising a plurality of the tabs (21), the tab group comprising a first tab group (3A) and a second tab group (4A), the first tab group (3A) and the second tab group (4A) being located at the same axial end of the winding body (10); The first tab group (3A) and the second tab group (4A) are respectively arranged on both sides of the winding axis of the winding body (10) and are arranged in alignment with each other.

12. The electrode assembly (1000) of claim 11, wherein, The number of tabs (21) in the first tab group (3A) is the same as the number of winding layers of the pole piece, and the alignment direction of the plurality of tabs (21) is from the second tab group (4A) to the first tab group (3A).

13. The electrode assembly (1000) of claim 10, wherein, The winding direction of the winding body (10) is the width direction of the tab (21), and along the alignment direction of the plurality of tabs (21), the width of the plurality of tabs (21) gradually decreases.

14. The electrode assembly (1000) of claim 10, wherein, The width of the plurality of tabs (21) gradually decreases in the direction away from the winding body (10).

15. The electrode assembly (1000) of claim 10, wherein, The side of the tab (21) away from the pole piece is arc-shaped (6); or, The two ends of the side of the tab (21) away from the pole piece are provided with chamfers (7).

16. The electrode assembly (1000) of claim 10, wherein, The tab group is a first polarity tab group, and the electrode assembly (1000) further comprises a second polarity tab group, the second polarity tab group and the first polarity tab group are respectively arranged at both ends of the same axial end of the winding body (10), one of the first polarity tab group and the second polarity tab group is a positive tab group (2A), and the other is a negative tab group (5A).

17. The electrode assembly (1000) of claim 16, wherein, The first polarity tab group is a positive tab group (2A); The second polarity tab group is a negative tab group (5A) and comprises a plurality of negative tabs, the plurality of negative tabs are respectively connected to different winding layers of the negative pole piece (13) and are arranged in alignment with each other, and along the alignment direction of the plurality of negative tabs, the height of the plurality of negative tabs gradually decreases.

18. The electrode assembly (1000) of claim 1, wherein, The pole piece structure (1) comprises a main body (110) configured to be wound to form a winding core (20), the main body (110) has a winding starting end (130) and a winding ending end (140), and the direction from the winding starting end (130) to the winding ending end (140) is a winding direction; A plurality of the tabs (21) are arranged on one side of the main body (110) in the winding direction, and along the winding direction, the height of the tabs (21) at odd positions and the height of the tabs (21) at even positions have opposite gradient trends.

19. The electrode assembly (1000) of claim 18, wherein, The height of the tabs (21) at odd positions decreases, and the height of the tabs (21) at even positions increases, wherein the height of a first tab is less than the height of a second tab.

20. The electrode assembly (1000) according to claim 18 or 19, wherein The electrode assembly (1000) has a winding state corresponding to a winding center plane (210), wherein in the winding state, the odd-numbered tabs (21) and the even-numbered tabs (21) are located on opposite sides of the winding center plane (210), respectively, and the projections of all tabs (21) in a first direction at least partially overlap, wherein the first direction is arranged at an angle to the winding center plane (210).

21. The electrode assembly (1000) of claim 20, wherein, In the winding state, all tabs (21) are bent towards the direction of the connecting piece and are welded to the connecting piece (8), wherein when the tabs (21) are in the bent state, the distance between the free end of the shortest tab (21) and the free end of the longest tab (21) is Y, satisfying: 0 mm≤Y≤1 mm.

22. The electrode assembly (1000) of claim 21, wherein, When the tabs (21) are in the bent state, the free ends of all tabs (21) are flush.

23. The electrode assembly (1000) of claim 21, wherein, Along the first direction, the main body portion (110) has a proximal end (160) close to the connecting piece (8), and the distance between the proximal end (160) and the connecting piece (8) is X, satisfying: 1 mm≤X≤3 mm.

24. A battery, comprising: at least one electrode assembly (1000) according to any one of claims 1 to 23; and a cover plate assembly connected to the tab structure (2) of the electrode assembly (1000).

25. The battery of claim 24, wherein, The cover plate assembly includes a connecting piece (8); a plurality of tabs (21) are arranged overlappingly away from one end of the tab and are welded to the same side of the connecting piece (8).

26. The battery of claim 25, wherein, The battery includes at least two electrode assemblies (1000), the tab structures (2) of the at least two electrode assemblies are arranged in alignment, and the connecting pieces (8) are welded to the tab structures (2) of the adjacent two electrode assemblies (1000).

27. The battery of claim 24, wherein, The cover plate assembly includes a connecting piece (8), the connecting piece (8) includes a positive connecting piece (81) and a negative connecting piece (82), the positive connecting piece (81) has a positive tab connecting portion, and the negative connecting piece (82) has a negative tab connecting portion; The battery further comprises: a shell (30); and a core package (50) arranged in the shell (30), the core package (50) includes a core (20), and the core (20) includes a main body portion (110) and a separator (12), the main body portion (110) includes a positive tab and a negative tab, wherein the positive tabs are all bent and welded to the positive tab connecting portion, and the negative tabs are all bent and welded to the negative tab connecting portion.

28. The battery of claim 27, wherein, The number of positive tabs is 2n, the height of the (2n-1)th positive tab is the smallest, the height of the 2nth positive tab is the largest, and the height of the first positive tab is smaller than the height of the second positive tab, wherein n≥1 and n is an integer.

29. The battery of claim 28, wherein, The height of the 2nth positive tab is positively correlated with the sum of the length of the negative tab root portion and the length of the positive tab root portion, the length of the positive tab welding area, and the length of the positive tab bending area.

30. The battery of claim 29, wherein, The height of the 2n positive electrode tab is a, the length sum of the diaphragm negative electrode tab root and the diaphragm positive electrode tab root is O, the length of the positive electrode tab welding area is L1, and the length of the positive electrode tab bending area is L2, and a=L1+L2+O is satisfied.

31. The battery of claim 30, wherein, The positive electrode tab connecting part includes two spaced apart connecting tabs (410), and the positive electrode tabs of the positive electrode tab are all welded to the connecting tabs (410) after being bent, wherein the length of the positive electrode tab welding area is positively correlated with the width of the welding mark and the width of the connecting tab (410).

32. The battery of claim 31, wherein, The positive electrode tab is configured to be welded to the connecting tab (410) through at least two rounds of welding process, and the width of the welding mark formed on the positive electrode tab (21) in the last round of welding process is W2, and the width of the connecting tab (410) is W3, and L1=0.5(W2+W3)+k1 is satisfied, wherein k1 is a first preset allowance.

33. The battery of claim 31, wherein, The core package (50) is provided as at least two, and the two core packages (50) form a core package pair, and the positive electrode tab is welded to the corresponding connecting tab (410) after being raised by a welding seat, wherein the length of the positive electrode tab bending area is positively correlated with the distance between the two core packages (50) before being combined and the thickness of a single core package (50), and is negatively correlated with the width of the positive electrode connecting piece, the height of the welding seat lifting, and the total thickness of all positive electrode tabs welded on the same connecting tab (410).

34. The battery of claim 33, wherein, The distance between the two core packages (50) before being combined is H3, the thickness of a single core package (50) is T0, the width of the positive electrode connecting piece is W1, the height of the welding seat lifting is H0, and the total thickness of all positive electrode tabs welded on the same connecting tab (410) is H4, and the following is satisfied: 。 35. The battery of claim 28, wherein, The positive electrode tab connecting part includes two spaced apart connecting tabs (410), and the positive electrode tabs of the positive electrode tab are all welded to the connecting tabs (410) after being bent, and the core package (50) is provided as at least two, and the two core packages (50) form a core package pair, wherein the height of the (2n-1) positive electrode tab is positively correlated with the length sum of the diaphragm negative electrode tab root and the diaphragm positive electrode tab root, the distance between the two core packages (50) in the core package pair before being combined, the width of the welding mark, and the width of the connecting tab (410), and is negatively correlated with the width of the positive electrode connecting piece.

36. The battery of claim 35, wherein, The height of the (2n-1) positive electrode tab is b, the distance between the two core packages (50) before being combined is H3, the width of the positive electrode connecting piece (8) is W1, the width of the welding mark is W2, the width of the connecting tab (410) is W3, and the length sum of the diaphragm negative electrode tab root and the diaphragm positive electrode tab root is O, and b=0.5(H3-W1)+0.5(W2+W3)+O+k2 is satisfied, wherein k2 is a second preset allowance.

37. The battery of claim 34 or 36, wherein, The distance between the two core packages (50) before being combined is positively correlated with the distance between the positive electrode connecting piece and the main body part (110) and the distance between the edge of the positive electrode connecting piece and the inner side wall of the shell (30).

38. The battery of claim 37, wherein, The distance between the two core packs (50) before they are combined is H3, the distance between the positive electrode connecting tab and the main body (110) is D1, and the distance between the edge of the positive electrode connecting tab and the inner side wall of the shell (30) is D2, satisfying: 。 39. The battery of claim 38, wherein, The shell (30) is connected with a shell cover (310), wherein the distance between the positive electrode connecting tab and the main body (110) is positively correlated with the height of the shell (30) and the diaphragm compression amount, and is negatively correlated with the distance between the positive electrode connecting tab and the shell cover (310), the thickness of the positive electrode connecting tab, the total thickness of all positive electrode tabs welded on the same connecting lug (410), and the distance between the diaphragm and the lower surface of the shell (30).

40. The battery of claim 39, wherein, The height of the shell (30) is H10, the diaphragm compression amount is k3, the distance between the positive electrode connecting tab and the shell cover (310) is H6, the thickness of the positive electrode connecting tab is H7, the total thickness of all positive electrode tabs welded on the same connecting lug (410) is H4, and the distance between the diaphragm and the lower surface of the shell (30) is H9, satisfying: D1= H10-H6-H7-H4-(H9-k3).

41. The battery of claim 40, wherein, The diaphragm compression amount satisfies the range: 1.5≤k3≤2.

5.

42. The battery of claim 41, wherein, The total thickness of the two core packs (50) is W6, and the width of the shell (30) is W5, satisfying: 0.5(W6-W1)≤D2≤0.5(W5-W1).

43. The battery of claim 42, wherein, The distance between the positive electrode connecting tab and the main body (110) has a maximum value and a minimum value, which are D1max and D1min respectively, and the distance between the edge of the positive electrode connecting tab and the inner side wall of the shell (30) has a maximum value and a minimum value, which are D2max and D2min respectively, wherein D1max=H10-H6-H7-H4-(H9-2.5), D1min=H10-H6-H7-H4-(H9-1.5), D2max=0.5(W5-W1), and D2min=0.5(W6-W1), satisfying: 。 44. The battery of any one of claims 28-43, wherein, The number of negative electrode tabs is set to (2n+2), the height of the (2n+1)th negative electrode tab is the smallest, the height of the (2n+2)th negative electrode tab is the largest, and the height of the first negative electrode tab is less than the height of the second negative electrode tab, wherein the height of the (2n+2)th negative electrode tab is the same as the height of the 2nth positive electrode tab.

45. A battery pack comprising the battery of any one of claims 24 to 44.

46. A method for designing an electrode assembly (1000) applied to the battery of any one of claims 27-44, the method comprising: obtaining a maximum height of the tabs (21) and a minimum height of the tabs (21) based on design parameters of the battery; in the winding direction, making the height of the tabs (21) at odd positions and the height of the tabs (21) at even positions have opposite gradient trends, and making all tabs (21) welded on the same tab (8) connection in the same core (20) at least partially coincide in the projection in the first direction.

47. The method of claim 46, wherein, The design parameters of the battery include a first design parameter and a second design parameter, the core packs (50) are provided as at least two, the two core packs (50) form a core pack pair, the maximum height of the tab (21) and the minimum height of the tab (21) are obtained based on the design parameters of the battery, including: Based on the first design parameter, the distance between the two core packs (50) before being combined is obtained; Based on the second design parameter and the distance between the two core packs (50) before being combined, the maximum height of the tab (21) and the minimum height of the tab (21) are obtained.

48. The method of claim 47, wherein, The tab connecting part includes two spaced connecting ears (410), the tab (21) is welded to the connecting ear (410) after being bent, the first design parameter includes: the height of the shell (30), the compression amount of the diaphragm, the distance between the connecting piece (8) and the shell cover (310), the thickness of the connecting piece (8), the total thickness of all tabs (21) welded on the same connecting ear (410), the distance between the diaphragm and the lower surface of the shell (30), the total thickness of the two core packs (50), and the width of the shell (30).

49. The method of claim 48, wherein, The distance between the two core packs (50) before being combined is obtained based on the first design parameter, including: Based on the height H10 of the shell (30), the compression amount k3 of the diaphragm, the distance H6 between the connecting piece (8) and the shell cover (310), the thickness H7 of the connecting piece (8), the total thickness H4 of all tabs (21) welded on the same connecting ear (410), and the distance H9 between the diaphragm and the lower surface of the shell (30), the distance D1 between the connecting piece (8) and the main body part (110) is obtained, wherein the following relationship is satisfied: D1= H10-H6-H7-H4-(H9-k3); Based on the total thickness W6 of the two core packs (50), the width W5 of the shell (30), and the width W1 of the connecting piece (8), the distance D2 between the edge of the connecting piece (8) and the inner side wall of the shell (30) is obtained, wherein the following relationship is satisfied: 0.5(W6-W1)≤D2≤0.5(W5-W1); Based on the distance D1 between the connecting piece (8) and the main body part (110) and the distance D2 between the edge of the connecting piece (8) and the inner side wall of the shell (30), the distance H3 between the two core packs (50) before being combined is obtained, wherein the following relationship is satisfied: 。 50. The method of claim 49, wherein, The distance between the connecting piece (8) and the main body (110) has a maximum value and a minimum value, respectively D1max and D1min, and the distance between the edge of the connecting piece (8) and the inner side wall of the shell (30) has a maximum value and a minimum value, respectively D2max and D2min, wherein D1max=H10-H6-H7-H4-(H9-2.5), D1min=H10-H6-H7-H4-(H9-1.5), D2max=0.5(W5-W1), D2min=0.5(W6-W1), and the following relationships are satisfied: 。 51. The method of claim 47, wherein, The tab connecting portion includes two spaced apart connecting ears (410), and the tab (21) is welded to the connecting ear (410) after being bent. The second design parameter includes the length of the diaphragm negative tab root and the diaphragm positive tab root, the width of the welding mark, the width of the connecting ear (410), the first preset allowance, the second preset allowance, the width of the connecting piece (8), the thickness of a single core package (50), and the height of the welding seat lifting.

52. The method of claim 51, wherein, Based on the second design parameter and the distance between the two core packages (50) before coalescence, the maximum height of the tab (21) and the minimum height of the tab (21) are obtained, including: Based on the width W2 of the welding mark, the width W3 of the connecting ear (410), and the first preset allowance k1, the length L1 of the welding area is obtained, wherein the following relationship is satisfied: L1=0.5(W2+W3)+k1; Based on the distance H3 between the two core packages (50) before coalescence, the width W1 of the connecting piece (8), the thickness T0 of a single core package (50), and the height H4 of the welding seat lifting, the length L2 of the tab bending area is obtained, wherein the following relationship is satisfied: ； Based on the length sum O of the diaphragm negative tab root and the diaphragm positive tab root, the length L1 of the welding area, and the length L2 of the tab bending area, the maximum height a of the tab (21) is obtained, wherein the following relationship is satisfied: a=L1+L2+O.

53. The method of claim 51, wherein, Based on the second design parameter and the distance between the two core packages (50) before coalescence, the maximum height of the tab (21) and the minimum height of the tab (21) are obtained, further including: Based on the length sum O of the diaphragm negative tab root and the diaphragm positive tab root, the distance H3 between the two core packages (50) before coalescence, the width W1 of the connecting piece (8), the width W2 of the welding mark, the width W3 of the connecting ear (410), and the second preset allowance k2, the minimum height b of the tab (21) is obtained, wherein the following relationship is satisfied: b=0.5(H3-W1)+0.5(W2+W3)+O+k2.

54. The method of any one of claims 46 to 53, wherein, In the winding direction, the height of the tab (21) located in the odd position and the height of the tab (21) located in the even position have opposite gradient trends, and the projections of all tabs (21) connected to the same connecting piece (8) in the same core (20) at least partially coincide in the first direction, including: The height of the tab (21) in odd-numbered positions is arranged to decrease in the winding direction, the height of the tab (21) in even-numbered positions is arranged to increase, and the projections of all the tabs (21) welded to the same connecting lug (410) in the same core (20) at least partially coincide in the first direction.

55. The method of claim 54, wherein, The height of the tab (21) in odd-numbered positions is arranged to decrease in the winding direction, the height of the tab (21) in even-numbered positions is arranged to increase, and the projections of all the tabs (21) welded to the same connecting lug (410) in the same core (20) at least partially coincide in the first direction. Based on the number of the tabs (21), the maximum height of the tabs (21), and the minimum height of the tabs (21), a tolerance of the height variation of the tabs (21) is obtained; The height of the tab (21) in odd-numbered positions is arranged to decrease in the winding direction, the height of the tab (21) in even-numbered positions is arranged to increase, and the projections of all the tabs (21) welded to the same connecting lug (410) in the same core (20) at least partially coincide in the first direction.

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