Electrode plate, cell and battery module

Abstract

An electrode plate, a cell and a battery module. The electrode plate comprises an electrode plate body (1) and N tags (2), wherein the electrode plate body (1) has a length direction and a width direction, which are perpendicular to each other; and the N tabs (2) are arranged at intervals in the length direction of the electrode plate body (1), the widths of bottom edges of the N tabs (2) gradually decrease and then increase in the length direction of the electrode plate body (1), and the N tabs (2) are wound around the electrode plate body (1) and are then overlapped, N being a positive integer greater than or equal to 3.

Description

Electrodes, cells and battery modules

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on April 30, 2024, with application number 202420954961.5. The entire contents of the above application are incorporated by reference into this application.

[0002] Technical Field

[0003] The present application relates to the field of battery technology, for example, to a pole piece, a battery cell and a battery module.

[0004] Background Art

[0005] Battery manufacturing using wound pole sheets is beneficial for increasing production speed and reducing production costs. To improve battery energy density, multi-tab pole sheets are often used for winding. During the multi-tab winding process, errors in the winding needle's dimensional accuracy and the thickness of the incoming pole sheet material can lead to tab misalignment after winding. Severe misalignment can affect the subsequent ultrasonic welding of the tabs to the adapter and the assembly of the battery cell, increasing defects during the production process and affecting product performance.

[0006] In the multi-tab wound battery cell disclosed in the related art, the width of the multiple tabs gradually decreases from the starting end to the end of the winding. The tabs with reduced width layer by layer after winding can avoid the impact of tab misalignment and make the alignment of the multiple tabs higher.

[0007] Technical issues

[0008] However, the above solution has the following problem: due to the decreasing width of the tabs, when there are a large number of tabs, one or more of the tabs at the end may be narrower. After winding the pole sheet, the overlapping tabs need to be ultrasonically welded. The ultrasonic weld marks formed on the tabs must meet certain dimensional requirements to ensure weld security and current flow capacity at the tab location. In the above solution, the width of the tab at the end may be less than the designed weld mark length, resulting in poor welding and seriously affecting battery performance.

[0009] Therefore, there is an urgent need for a pole piece, a battery cell and a battery module to avoid the above situation.

[0010] Technical Solutions

[0011] In a first aspect, the present application provides a pole piece, comprising:

[0012] The pole piece body has a length direction and a width direction perpendicular to each other;

[0013] N tabs are spaced apart along the length direction of the pole piece body, the bottom widths of the N tabs decrease and then increase in the length direction of the pole piece body, and the N tabs overlap after the pole piece body is wound;

[0014] N is a positive integer greater than or equal to 3.

[0015] For example, the N tabs include a middle tab and two end tabs located at both ends;

[0016] In response to N being an odd number, the (N+1) / 2th tab is the middle tab;

[0017] In response to N being an even number, the N / 2th tab and the (N / 2)+1th tab are middle tabs;

[0018] Among the N tabs, the bottom width of the middle tab is the narrowest, and the bottom widths of the two end tabs are the same.

[0019] For example, the bottom width of the end tab is a, the bottom width of the middle tab is b, and b < a;

[0020] In response to N being an odd number, the difference in bottom width between two adjacent tabs is Δw=2(ab) / (N-1);

[0021] In response to N being an even number, the difference in bottom width between the two middle tabs Δw=0; the difference in bottom width between the non-middle tabs, and the difference in bottom width between the middle tabs and the non-middle tabs are both Δw=2(ab) / (N-2); the non-middle tabs are the tabs other than the middle tabs.

[0022] For example, the bottom width a of the end tab and the bottom width b of the middle tab satisfy: b≥a / 2.

[0023] For example, the difference Δw between the bottom widths of two adjacent tabs ranges from 0 to 4 mm.

[0024] For example, ultrasonic weld marks are respectively provided on N tabs, and the N tabs are fixedly connected at the ultrasonic weld marks. The size of the ultrasonic weld marks along the length direction of the pole body is L, and the bottom width of the tab with the narrowest bottom width is 0.8mm to 2mm larger than L.

[0025] For example, the heights of N tabs are consistent;

[0026] Alternatively, the heights of the N pole tabs gradually increase along the length direction of the pole piece body.

[0027] For example, the center distance between two adjacent pole ears gradually increases along the length direction of the pole piece body.

[0028] For example, the tab is trapezoidal, and the lower base of the tab is connected to the pole piece body, and the bottom width is the lower base width of the tab.

[0029] In the second aspect, the present application provides a battery cell, including a shell and a core assembly arranged in the shell, the core assembly includes a first diaphragm, a positive electrode sheet, a second diaphragm and a negative electrode sheet stacked in sequence, and the positive electrode sheet and the negative electrode sheet respectively use the above-mentioned electrodes.

[0030] In a third aspect, the present application provides a battery module, including a CCS component and a plurality of battery cells as described above, wherein the CCS component is configured to collect voltage signals and temperature signals of the battery cells.

[0031] Beneficial effects

[0032] The present application provides a pole piece, a battery cell, and a battery module. The pole piece includes a pole piece body and N pole tabs disposed on the pole piece body. One end of the pole piece body is fixed, and the other end is wound to form a winding core. After winding, the N pole tabs overlap. The bottom widths of the N pole tabs decrease and then increase along the length direction of the pole piece body. Among the N overlapping pole tabs, adjacent pole tabs have different bottom widths. Therefore, the pole tab with the smaller bottom width will fall within the area of ​​the pole tab with the larger bottom width. Even if there is a slight deviation, the edges of the pole tab with the smaller bottom width generally do not exceed the edges of the pole tab with the larger bottom width. The design of the width difference between adjacent pole tabs can offset the pole tab misalignment caused by the winding needle size accuracy and the pole piece thickness accuracy. In addition, since the bottom widths of the N tabs decrease and then increase along the length direction of the pole piece body, rather than showing a decreasing trend, the bottom width of the tab with the narrowest bottom width will not be too narrow, so that the width of the tab meets the requirements of ultrasonic welding, ensuring the welding firmness and current capacity of the N tabs, and improving the yield rate of the battery.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic structural diagram of a first pole piece provided in a possible embodiment of the present application;

[0035] FIG2 is a schematic structural diagram of a second pole piece provided in a possible embodiment of the present application;

[0036] FIG3 is a schematic diagram of a pole piece wound into a core assembly according to a possible embodiment of the present application;

[0037] FIG4 is a schematic cross-sectional view in the height direction of a plurality of pole tabs after winding of a first pole piece provided by a possible embodiment of the present application;

[0038] FIG5 is a schematic cross-sectional view in the height direction of a plurality of pole tabs after winding of a second pole piece provided by a possible embodiment of the present application;

[0039] FIG6 is a schematic structural diagram of a battery module provided in a possible embodiment of the present application.

[0040] In the picture:

[0041] 1. Pole body; 2. Pole ear;

[0042] 100. core assembly;

[0043] 200, battery cell;

[0044] 300.CCS components.

[0045] Modes for Carrying Out the Invention

[0046] As shown in Figures 1 and 2, this embodiment provides a pole piece, which can be, for example, a multi-tab pole piece, comprising a pole piece body 1 and N pole tabs 2. This pole piece can not only improve the misalignment between the pole tabs 2 after the multi-tab pole piece is wound, but also ensure that the bottom width of the pole tab 2 meets the requirements of ultrasonic welding, thereby improving the yield rate of the battery.

[0047] The pole piece body 1 has a length direction and a width direction that are perpendicular to each other. Specifically, in FIG1 and FIG2 , the left-right direction is the length direction of the pole piece body 1 , and the up-down direction is the width direction of the pole piece body 1 .

[0048] N pole tabs 2 are arranged at intervals along the length direction of the pole piece body 1, and the bottom edge widths of the N pole tabs 2 decrease and then increase along the length direction of the pole piece body 1, and the N pole tabs 2 overlap after the pole piece body 1 is wound; N is a positive integer greater than or equal to 3, such as N is 5, 6, 7, 8, etc., which is selected according to the design requirements of the battery.

[0049] When the electrode is wound, one end of the electrode body 1 is fixed and the other end is wound to form a winding core. After winding, N pole tabs 2 overlap, as shown in Figures 3, 4 and 5. The overlapping N pole tabs 2 are welded together using an ultrasonic welding process and then electrically connected to the pole posts on the battery cover through adapters. In this embodiment, the bottom widths of the N pole tabs 2 decrease and then increase along the length direction of the electrode body 1. Among the N overlapping pole tabs 2, the adjacent two pole tabs 2 have different bottom widths. Therefore, the pole tab 2 with a smaller bottom width will fall within the area of ​​the pole tab 2 with a larger bottom width. Even if there is a slight deviation, the edges of the pole tab 2 with a smaller bottom width generally do not exceed the edges of the pole tab 2 with a larger bottom width. The design of the width difference between adjacent pole tabs 2 can offset the misalignment of the pole tabs 2 caused by the winding needle size accuracy and the pole sheet thickness accuracy. In addition, since the bottom widths of the N tabs 2 decrease and then increase along the length direction of the pole body 1, rather than showing a decreasing trend, the bottom width of the tab 2 with the narrowest bottom width is not too narrow, so that the width of the tab 2 meets the ultrasonic welding requirements, ensuring the welding firmness and current capacity of the N tabs 2, and improving the yield rate of the battery.

[0050] As shown in Figures 1 and 2, a plurality of tabs 2 are formed from the original electrode sheet by cutting equipment. Furthermore, each side of the electrode sheet body 1 along the width direction has N tabs 2, and the N tabs 2 on both sides are arranged one by one opposite each other. Before winding, the electrode sheet shown in Figures 1 and 2 is cut along the center line in the longitudinal direction to form two upper and lower electrode sheets, both of which can be used for winding. For example, the bottom widths of the two tabs 2 facing each other along the width direction are completely consistent, thereby improving cutting efficiency.

[0051] The N pole tabs 2 include a middle pole tab and two end pole tabs located at both ends. After the pole piece body 1 is wound, the two end pole tabs are located at the outermost sides.

[0052] If N is an odd number, the (N+1) / 2th tab 2 is the middle tab, i.e., the middle tab 2 is the middle tab. For example, referring to Figure 1 , if N is 5, the third tab 2 is the middle tab, i.e., the tab 2 at position A3 is the middle tab, and the number of tabs 2 on either side of the middle tab is the same. If N is 7, the fourth tab 2 is the middle tab, and so on. These examples are not listed here one by one.

[0053] If N is an even number, the N / 2th and (N / 2)+1th tabs 2 are middle tabs, i.e., the two middle tabs 2 are middle tabs. For example, referring to Figure 2 , if N is 6, the third and fourth tabs 2 are middle tabs, i.e., the tabs 2 at positions B3 and B4 are middle tabs, and the number of tabs 2 on either side of these two middle tabs is the same. If N is 8, the fourth and fifth tabs 2 are middle tabs, and so on, and these examples are not listed here one by one.

[0054] Among the N tabs 2 in this embodiment, the bottom width of the middle tab is the narrowest. Specifically, in FIG1 , the bottom width of the middle tab at position A3 is the narrowest. Among the tabs 2 on both sides, the bottom width of the tab 2 at position A1 is greater than the bottom width of the tab 2 at position A2, and the bottom width of the tab 2 at position A5 is greater than the bottom width of the tab 2 at position A4. Specifically, in FIG2 , the bottom width of the middle tabs at positions B3 and B4 is the narrowest. Among the tabs 2 on both sides, the bottom width of the tab 2 at position B1 is greater than the bottom width of the tab 2 at position B2, and the bottom width of the tab 2 at position B6 is greater than the bottom width of the tab 2 at position B5. Because the bottom width of the middle tab is the narrowest, the bottom widths of the tabs 2 on both sides increase from the middle to the ends. This compensates for the misalignment of the tabs 2 while maximizing the bottom width of the narrowest tab 2, preventing it from being too narrow to affect subsequent ultrasonic welding.

[0055] The schematic diagram of the overlap of the five pole tabs 2 in Figure 1 after the pole piece body 1 is wound is shown in Figure 4, and the narrowest middle pole tab is located in the middle of the five pole tabs 2. The schematic diagram of the overlap of the six pole tabs 2 in Figure 2 after the pole piece body 1 is wound is shown in Figure 5, and the two narrowest middle pole tabs are located in the middle of the six pole tabs 2. Figures 4 and 5 show schematic cross-sectional views of the plurality of pole tabs in the height direction after the pole piece body 1 is wound, taking the left end of the pole piece body 1 as an example of being fixed. That is, after winding, pole tab A1 in Figure 4 is located at the innermost side, and pole tab A5 is located at the outermost side. In Figure 5, pole tab B1 is located at the innermost side, and pole tab B6 is located at the outermost side.

[0056] For example, the bottom widths of the two end tabs are consistent. That is, the bottom widths of the tabs 2 at positions A1 and A5 in Figure 1 are consistent, and the bottom widths of the tabs 2 at positions B1 and B6 in Figure 2 are consistent. As shown in Figures 4 and 5 , the two end tabs are located at the innermost and outermost sides, and the edges of the remaining tabs 2 do not extend beyond the edges of the two end tabs, ensuring uniformity after the multiple tabs 2 are overlapped.

[0057] For example, except for the two adjacent middle tabs, the difference in base width between the other two adjacent tabs 2 is the same. For example, the base width of the end tab is a, and the base width of the middle tab is b, where b < a. If N is an odd number, then the difference in base width between the two adjacent tabs 2 is Δw = 2(ab) / (N-1).

[0058] Referring to Figure 1, the bottom width of the tab 2 at position A3 is b, the bottom width of the tabs 2 at positions A1 and A5 is a, the bottom widths of the two tabs 2 at positions A2 and A4 are the same, N is 5, the bottom width difference between two adjacent tabs 2 is Δw = (ab) / 2, the bottom width difference between the two tabs 2 at positions A5 and A4 is equal to the bottom width difference between the two tabs 2 at positions A4 and A3, and the bottom width difference between the two tabs 2 at positions A1 and A2 is equal to the bottom width difference between the two tabs 2 at positions A2 and A3.

[0059] If N is an even number, for the two middle tabs in the middle, the difference in bottom width Δw=0; except for the two middle tabs, the remaining tabs are non-middle tabs, and the difference in bottom width between the non-middle tabs, and the difference in bottom width between the middle tabs and the non-middle tabs are both Δw=2(ab) / (N-2).

[0060] Referring to Figure 2 , the bottom width of the tabs 2 at positions B3 and B4 is b, the bottom width of the tabs 2 at positions B1 and B6 is a, and the bottom widths of the tabs 2 at positions B2 and B5 are the same. N is 6, and the bottom width difference between adjacent tabs 2 is Δw = 2(ab) / (N-2). The bottom width difference between the tabs 2 at positions B6 and B5 is equal to the bottom width difference between the tabs 2 at positions B5 and B4, and the bottom width difference between the tabs 2 at positions B1 and B2 is equal to the bottom width difference between the tabs 2 at positions B2 and B3. (ab) is the total width difference between the widest and narrowest tabs 2. In this embodiment, this total width difference is evenly distributed between adjacent tabs 2, ensuring that each adjacent tab 2 has an anti-misalignment effect.

[0061] For example, the bottom width a of the end tab and the bottom width b of the middle tab satisfy: b ≥ a / 2. This dimensional design minimizes the total difference in width between the widest tab 2 and the narrowest tab 2, ensuring that the width of the narrowest tab 2 is not too narrow and conserves material. For example, the bottom width b of the middle tab is b = a / 2; or the bottom width b of the middle tab is b = a / 3. For example, the bottom width a of the end tab is 6 mm, and the bottom width b of the middle tab is 3 mm.

[0062] For example, the value range of the difference Δw between the bottom widths of two adjacent tabs 2 is 0 to 4 mm. For example, when N is an even number, there is a case where Δw=0, and the bottom width difference Δw=0 specifically refers to the bottom width difference between the two middle tabs. For the bottom width difference of the tabs when N is an odd number, the bottom width difference between the non-middle tabs when N is an even number, and the bottom width difference Δw between the middle tab and the non-middle tab when N is an even number, the value range is 0.1mm to 4mm. For example, the bottom width difference Δw is 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, etc. In this embodiment, it can be 2mm, 3mm, or 4mm to ensure that there is sufficient misalignment tolerance between the two adjacent tabs 2 and that a large amount of tab 2 material is not wasted.

[0063] Referring to Figure 3 , for two adjacent tabs 2 with a non-zero difference in bottom width, the misalignment between the left and right sides of the narrower tab 2 is the misalignment margin Q, where Q = Δw / 2. This means that the allowable misalignment displacement between the left and right edges of the narrower tab 2 is Δw / 2. When the centerlines of the two adjacent tabs 2 coincide, the distance between the edge of the narrower tab 2 and the edge of the wider tab 2 is exactly Δw / 2. The misalignment margin Q ranges from 0.05mm to 2mm. For example, the misalignment margin Q ranges from 0.05mm to 2mm. Exemplary values ​​include 0.05mm, 0.5mm, 1mm, 1.5mm, and 2mm, ensuring sufficient misalignment tolerance between adjacent tabs 2 and effectively offsetting tab 2 misalignment caused by winding needle dimensional accuracy and pole piece thickness accuracy.

[0064] The N tabs 2 are subsequently connected together using an ultrasonic welding process. After the ultrasonic welding head is pressed, ultrasonic weld marks are formed on the N tabs 2, and the N tabs 2 are fixedly connected at the ultrasonic weld marks. For the ultrasonic weld marks of the battery cell tabs 2, it is necessary to specify their size range during design to ensure the stability after ultrasonic connection and the flow capacity of the tabs 2. In this embodiment, the size of the ultrasonic weld mark along the length direction of the pole piece body 1 is L, and the bottom width of the tab 2 with the narrowest bottom width is 0.8mm to 2mm larger than L. That is, the bottom width value b of the middle tab in Figures 1 and 2 is 0.8mm to 2mm larger than the designed length L of the ultrasonic weld mark, for example, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, etc., to ensure that each tab 2 has a complete ultrasonic weld mark, ensure the connection strength of the tabs 2 after ultrasonic welding and the flow capacity after assembly into the battery cell 200, thereby improving the performance of the battery product.

[0065] For example, the bottom width b of the middle tab is 1 mm larger than the designed length L of the ultrasonic weld mark, which can minimize the material usage while ensuring that each tab 2 has a complete ultrasonic weld mark.

[0066] In some embodiments, referring to FIG. 1 and FIG. 2 , the heights of the N tabs 2 are consistent, so that the top edges of the N tabs 2 after winding are as flat as possible.

[0067] In some embodiments, the heights of the N tabs 2 may gradually increase along the length of the pole piece body 1. After the pole piece body 1 is wound, the top portions of the N tabs 2 may be cut off to make the tops of the overlapping N tabs 2 more flush.

[0068] In this embodiment, the center-to-center distance between adjacent tabs 2 gradually increases along the length of the pole piece body 1, ensuring that N tabs 2 overlap during the winding process. One end of the pole piece body 1 serves as the winding insertion end (which is fixed), and the other end serves as the winding end. From the winding insertion end to the winding end, the center-to-center distance between adjacent tabs 2 gradually increases to ensure that N tabs 2 overlap after winding. That is, the end with the smaller center-to-center distance serves as the winding insertion end for winding.

[0069] Referring to Figures 1 and 2, the tab 2 is trapezoidal, with its lower base connected to the pole piece body 1, which can improve the strength of the base of the tab 2 and prevent the tab 2 from breaking due to pulling. For example, the tab 2 is an isosceles trapezoid, ensuring uniform strength at the base of both sides of the tab 2, and ensuring the quality of multiple tabs 2 after winding and overlapping, thereby improving the current flow capacity of the tab 2.

[0070] This embodiment also provides a battery cell 200, including a shell and a winding core assembly 100 arranged in the shell, the winding core assembly 100 includes a first diaphragm, a positive electrode sheet, a second diaphragm and a negative electrode sheet stacked in sequence, and both the positive electrode sheet and the negative electrode sheet use the above-mentioned electrode sheets. For example, a third diaphragm and a packaging film are stacked on the side of the negative electrode sheet facing away from the second diaphragm, and the winding core assembly 100 is formed after being wound together. As shown in Figure 3, it is a cross-sectional view of the winding core assembly 100. Among the multiple overlapping pole tabs 2 on the left side and the multiple overlapping pole tabs 2 on the right side, one is formed by winding the positive electrode sheet and the other is formed by winding the negative electrode sheet. The winding core assembly 100 can eliminate the misalignment of the pole tabs 2, ensure that the N pole tabs 2 of the positive electrode sheet and the N pole tabs 2 of the negative electrode sheet can meet the subsequent ultrasonic welding requirements, and improve the performance of the battery cell 200.

[0071] The shell of the battery cell 200 includes a containing shell and a cover plate. The positive electrode column and the negative electrode column are provided on the cover plate. N overlapping tabs 2 are welded to the corresponding electrode columns through adapters.

[0072] Figure 6 is a schematic diagram of the structure of a battery module provided in a possible embodiment of the present application. As shown in Figure 6, this embodiment also provides a battery module comprising a plurality of battery cells 200 as described above. The battery module also includes a CCS (Cells Contact System) assembly 300, configured to collect voltage and temperature signals from the battery cells 200. The battery module with the battery cells 200 described above was assembled smoothly and achieved excellent performance.

Claims

1. Pole piece, including: The pole piece body (1) has a length direction and a width direction that are perpendicular to each other; N pole ears (2) are arranged at intervals along the length direction of the pole piece body (1), the bottom widths of the N pole ears (2) decrease and then increase in sequence along the length direction of the pole piece body (1), and the N pole ears (2) overlap after the pole piece body (1) is wound; N is a positive integer greater than or equal to 3.

2. The pole piece according to claim 1, wherein: The N pole ears (2) include a middle pole ear and two end pole ears located at both ends; In response to N being an odd number, the (N+1) / 2th pole lug (2) is the middle pole lug; In response to N being an even number, the N / 2th pole lug (2) and the (N / 2)+1th pole lug (2) are the middle pole lugs; Among the N pole tabs (2), the width of the bottom edge of the middle pole tab is the narrowest, and the widths of the bottom edges of the two end pole tabs are consistent.

3. The pole piece according to claim 2, wherein: The bottom width of the end tab is a, the bottom width of the middle tab is b, and b<a; In response to N being an odd number, the difference in bottom width between two adjacent pole tabs (2) is Δw=2(ab) / (N-1); In response to N being an even number, the difference in bottom width between the two middle pole ears Δw=0; the difference in bottom width between the non-middle pole ears, and the difference in bottom width between the middle pole ears and the non-middle pole ears are Δw=2(ab) / (N-2) respectively; the non-middle pole ears are the pole ears other than the middle pole ears.

4. The pole piece according to claim 3, wherein: The bottom width a of the end tab and the bottom width b of the middle tab satisfy: b≥a / 2.

5. The pole piece according to claim 1, wherein: The value range of the difference Δw between the bottom widths of two adjacent tabs (2) is 0 to 4 mm.

6. The pole piece according to any one of claims 1 to 5, wherein: Ultrasonic weld marks are respectively provided on the N pole tabs (2), and the N pole tabs (2) are fixedly connected at the ultrasonic weld marks. The dimension of the ultrasonic weld marks along the length direction of the pole piece body (1) is L, and the bottom width of the pole tab (2) with the narrowest bottom width is 0.8 mm to 2 mm larger than L.

7. The pole piece according to any one of claims 1 to 5, wherein: The N tabs (2) have the same height; Alternatively, the heights of the N pole tabs (2) gradually increase along the length direction of the pole piece body (1).

8. The pole piece according to any one of claims 1 to 5, wherein: The center distance between two adjacent pole ears (2) gradually increases along the length direction of the pole piece body (1).

9. The pole piece according to any one of claims 1 to 5, wherein: The pole lug (2) is trapezoidal, and the lower base of the pole lug (2) is connected to the pole piece body (1), and the base width is the lower base width of the pole lug.

10. A battery cell, comprising a shell and a winding core assembly (100) arranged in the shell, the winding core assembly (100) comprising a first diaphragm, a positive electrode sheet, a second diaphragm and a negative electrode sheet stacked in sequence, the positive electrode sheet and the negative electrode sheet respectively using the electrode sheet according to any one of claims 1 to 9.

11. A battery module, comprising a CCS component and a plurality of battery cells as claimed in claim 10, wherein the CCS component is configured to collect voltage signals and temperature signals of the battery cells.

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