Pole piece unit and cylindrical battery cell
By designing the tab part and the electrode part of the electrode unit to be integrated, and the height of the tab part varies along the length direction, the problem of the full tab electrode covering the center hole of the core after winding is solved, which improves the welding effect and reliability of the cell and avoids the risk of short circuit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BATTERO TECH CORP LTD
- Filing Date
- 2022-09-07
- Publication Date
- 2026-07-24
AI Technical Summary
After winding, the tabs can easily cover the center hole of the core, resulting in uneven stacking of the tabs after bending, which affects the welding effect of the current collector and poses a short circuit risk, reducing the reliability of the cell.
Design an electrode unit in which the tab and the electrode portion are integrally formed. The length of the tab is no greater than that of the electrode portion, and the height varies along the length direction, having a minimum and a maximum value. The height variation is located at both ends of the tab to prevent short circuits caused by inserting the tab into adjacent electrode units after it has been cut, and to ensure the flatness of the tab end face.
The design of the tabs avoids the tab end face being concave or convex, prevents the current collector from being poorly soldered, improves the reliability and welding effect of the battery cell, and ensures the safety and performance of the battery cell.
Smart Images
Figure CN122455871A_ABST
Abstract
Description
[0001] This is a divisional application. The parent application was filed on September 7, 2022, with application number 2022110911354 and titled "Electrode Unit and Cylindrical Cell". Technical Field
[0002] This invention relates to the field of secondary battery technology, and more particularly to an electrode unit and a cylindrical battery cell. Background Technology
[0003] With the growing popularity of large cylindrical battery cells, full-tab electrode sheets offer significant advantages over traditional welded electrode sheets. Full-tab electrode sheets result in lower internal resistance and more uniform heat generation and lower temperature rise during overcurrent. While full-tab electrode sheets offer numerous advantages, practical issues arise. After winding, the inner and outer rings of the core have different radii of curvature. This can cause the electrode tabs to bend and cover the center hole of the core, affecting electrode welding. Furthermore, the smaller radius of curvature at the inner ring leads to more stacked layers after tab bending, causing a bulge at the inner ring that is higher than the outer ring, impacting the current collector welding effect and reducing cell yield.
[0004] Currently, most designs employ a method of cutting off part of the tabs, resulting in a tabless design at the innermost ring of the core. While this design effectively prevents the tabs from blocking the central hole of the core after bending, it causes the tab end faces to be concave, making the current collector welding prone to incomplete soldering and affecting cell reliability. Furthermore, the bent tabs at the innermost ring of the core can easily insert backwards into the diaphragm layer at the tabless section of the inner ring, potentially causing a short circuit within the cell. Therefore, a new type of electrode unit and cylindrical cell is urgently needed to address these issues. Summary of the Invention
[0005] The purpose of this invention is to provide an electrode unit and a cylindrical battery cell, wherein the electrode unit is used to assemble a cylindrical battery cell.
[0006] To achieve the above objectives, the present invention provides an electrode unit comprising: an electrode portion and an electrode tab portion integrally disposed thereon; the length of the electrode tab portion is not greater than the length of the electrode portion; the height of the electrode tab portion varies along the length direction of the electrode tab portion; the height of the electrode tab portion has a minimum value H1 and a maximum value H2, wherein H1 is less than H2, H1 is 0 or any positive number, and H2 is any positive number; the maximum height of the electrode tab portion and the minimum height of the electrode tab portion are respectively located at both ends of the electrode tab portion.
[0007] The beneficial effects of the method of the present invention are as follows: It features an integrally formed electrode portion and a tab portion; the length of the tab portion is not greater than the length of the electrode portion; the height of the tab portion varies along its length; the height of the tab portion has a minimum value H1 and a maximum value H2, where H1 is less than H2, H1 is 0 or any positive number, and H2 is any positive number; the maximum height and minimum height of the tab portion are located at opposite ends of the tab portion. This avoids short circuits caused by inserting the tab portion into the electrode portion of an adjacent electrode unit after it has been cut. Because the height of the tab portion varies, the flatness of the tab end face is high, preventing concavity or convexity of the cylindrical battery end face, avoiding poor soldering of the current collector, and ensuring cell reliability.
[0008] Optionally, the length relationship between the electrode portion and the tab portion satisfies: L = L1 + L2 + L3; 0 ≦ L1 / L ≦ 1 / 15; 0 ≦ L3 / L ≦ 1 / 15; the length of the electrode portion is L, where L is any positive number; the distance from the maximum height of the tab portion to the head end of the electrode portion is L1, where L1 is 0 or any positive number; the length of the tab portion is L2, where L2 is any positive number; and the distance from the maximum height of the tab portion to the tail end of the electrode portion is L3, where L3 is any positive number.
[0009] Optionally, the electrode tab is provided with a plurality of slits; the plurality of slits are distributed non-uniformly on the electrode tab.
[0010] Optionally, the spacing between adjacent slits is positively correlated with the height of the tab.
[0011] Optionally, the plurality of slits are parallel to each other; the acute angle formed by the slits and one side edge of the electrode portion is greater than 0 degrees and less than 90 degrees.
[0012] Optionally, at least one side of the tab is provided with an active coating.
[0013] Secondly, the present invention provides a cylindrical battery cell, comprising a wound core module, wherein the wound core module comprises a positive electrode unit and a negative electrode unit stacked together, wherein both the positive electrode unit and the negative electrode unit are configured as electrode units as described in any of the preceding claims, and the wound core module is spirally wound; the maximum height of the tab portion of the electrode unit is located at the edge of the cylindrical battery cell, and the minimum height of the tab portion is located on the axial side of the cylindrical battery cell.
[0014] Optionally, the core module forms a central hole; the two ends of the cylindrical cell are respectively provided with a positive current collector and a negative current collector; the positive electrode post is welded to the positive current collector.
[0015] Optionally, the tabs of both the positive electrode unit and the negative electrode unit are bent toward the axis of the cylindrical cell; the positive current collector is welded to the tab of the positive electrode unit; and the negative current collector is welded to the tab of the negative electrode unit.
[0016] Optionally, the cylindrical cell further includes a separator and a packaging shell; the separator is disposed between the positive electrode unit and the negative electrode unit; the packaging shell is located outside the positive current collector, the positive electrode unit and the negative electrode unit; and the packaging shell contains an electrolyte. Attached Figure Description
[0017] Figure 1 A schematic diagram of a electrode unit in which the length of the electrode portion is equal to the length of the electrode tab portion, provided by the present invention; Figure 2 A schematic diagram of the structure of an electrode unit in which the length of the electrode portion is greater than the length of the electrode tab portion, provided by the present invention; Figure 3 A schematic diagram of a electrode unit whose height variation curve of the electrode ear is arranged in the shape of a convex function, provided by the present invention; Figure 4 A schematic diagram of a electrode unit with a concave function-shaped height variation curve for the electrode tab provided by the present invention; Figure 5 A schematic diagram of a electrode unit with a stepped height variation curve for the electrode tab provided by the present invention; Figure 6 A schematic diagram of a electrode unit with a wavy height variation curve for the electrode tab provided by the present invention; Figure 7 This invention provides a schematic diagram of the structure of an electrode unit having a slit area and a reference area; Figure 8 A cross-sectional structural diagram of a wound cylindrical battery cell provided by the present invention; Figure 9 A schematic diagram of an unfolded cylindrical battery cell provided by the present invention; Figure 10 A schematic cross-sectional view of a cylindrical battery cell that is flattened after the tab is bent, as provided by the present invention. Figure 11 This is a schematic diagram of the electrode unit in Embodiment 1 of the present invention; Figure 12 This is a schematic diagram of the electrode unit in Embodiment 2 of the present invention; Figure 13 A schematic diagram of the electrode unit of Comparative Example 1 provided by the present invention; Figure 14This is a schematic diagram of the electrode unit of Comparative Example 2 provided by the present invention.
[0018] Numbering on the map: 100. Core module; 101. Electrode section; 102. Electrode lug section; 1021. Slit area; 1022. Reference area; 103. Slit; 110. Positive electrode unit; 111. Positive current collector; 112. Positive electrode post; 113. Insulating sheet; 120. Negative electrode unit; 121. Negative current collector; 130. Center hole; 140. Encapsulation shell. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.
[0020] Figure 1 This is a schematic diagram of the structure of an electrode unit in which the length of the electrode portion is equal to the length of the electrode tab portion, as provided by the present invention.
[0021] To address the problems existing in the prior art, the present invention provides a method such as... Figure 1 The electrode unit shown includes an integrally formed electrode portion 101 and an electrode tab portion 102. The length of the electrode tab portion 102 is not greater than the length of the electrode portion 101. Figure 1 The height of the tab 102 decreases monotonically from horizontal to right. The maximum height of the tab 102 is located at the same end of the electrode unit as the edge of the electrode portion 101.
[0022] In other embodiments, the height of the tab 102 increases monotonically along a horizontal rightward direction.
[0023] In some specific embodiments, the length of the tab portion 102 is equal to the length of the electrode portion 101.
[0024] In other specific embodiments, the length of the tab portion 102 is less than the length of the electrode portion 101.
[0025] In some other embodiments, the height of the tab 102 increases monotonically along its length.
[0026] In some other embodiments, the height of the tab 102 decreases monotonically along its length.
[0027] It is worth noting that the electrode portion and the tab portion are integrally formed. The length of the tab portion is no greater than the length of the electrode portion. The height of the tab portion varies along its length. The height of the tab portion has a minimum value H1 and a maximum value H2, where H1 is less than H2, H1 is 0 or any positive number, and H2 is any positive number. The maximum height and the minimum height of the tab portion are located at opposite ends of the tab portion. This design prevents short circuits caused by inserting the tab portion into the electrode portion of an adjacent electrode unit after it has been cut. Because the height of the tab portion varies, the end face of the tab portion has high flatness, preventing the end face of the cylindrical battery from being concave or convex, avoiding poor soldering of the current collector, and ensuring the reliability of the cell.
[0028] In some specific embodiments, the electrode portion 101 is rectangular, and the electrode tab portion 102 is triangular.
[0029] In other embodiments, the electrode portion 101 is arranged in a parallelogram shape. One side of the electrode tab portion 102 is curved.
[0030] In some other embodiments, the electrode portion 101 and the electrode tab portion 102 are arranged in any geometric shape.
[0031] Figure 2 This is a schematic diagram of the structure of an electrode unit in which the length of the electrode portion is greater than the length of the electrode tab portion, as provided by the present invention.
[0032] In some embodiments, such as Figure 2 As shown, the minimum height of the tab portion 102 is H1. The maximum height of the tab portion 102 is H2. The length of the electrode portion 101 is L. The length of the tab portion 102 is L2.
[0033] In some embodiments, the tab portion 102 is provided with a plurality of slits 103. The spacing between each pair of adjacent slits 103 is set differently.
[0034] In some embodiments, the spacing between adjacent slits 103 is positively correlated with the height of the tab 102.
[0035] In some specific embodiments, the spacing between adjacent slits 103 is proportional to the height of the tab 102.
[0036] In other embodiments, the spacing between adjacent slits 103 is proportional to the square of the height of the tab 102.
[0037] In other embodiments, reference is made to Figure 2 Starting from the right end of the electrode portion 101, along Figure 2 In the horizontal direction to the left, the height of the tab 102 within length L1 remains 0. Within length L2, the height of the tab 102 changes from H1 to H2. Within length L3, the height of the tab 102 remains 0. The length relationship between the electrode plate and the tab satisfies: L = L1 + L2 + L3. 0 ≦ L1 / L ≦ 1 / 15. 0 ≦ L3 / L ≦ 1 / 15. The length of the electrode plate is L, where L is any positive number. The distance from the maximum height of the tab to the head end of the electrode plate is L1, where L1 is 0 or any positive number. The length of the tab is L2, where L2 is any positive number. The distance from the maximum height of the tab to the tail end of the electrode plate is L3, where L3 is any positive number. Along... Figure 2 In the horizontal direction to the left, the spacing between adjacent slits 103 on the tab 102 is set sequentially from D1 to D... n Let n be any positive integer. For any D n All have D n Greater than D n-1 .
[0038] In some specific embodiments, L1=0, L3=0, and L=L2. In this case, the length L of the electrode portion is equal to the length L2 of the electrode tab portion.
[0039] In other specific embodiments, L1 / L = 1 / 15, L3 / L = 1 / 15, and L2 / L = 13 / 15. In this case, the length L2 of the electrode tab is taken as the minimum value, which is 13 / 15 of the length L of the electrode plate.
[0040] In some specific embodiments, L1=0, L3 / L=1 / 15, and L2 / L=14 / 15. In this case, the right end of the electrode portion and the right end of the electrode tab portion are on the same straight line.
[0041] In some specific embodiments, L1 / L=1 / 15, L3=0, and L2 / L=14 / 15. In this case, the left end of the electrode portion and the left end of the electrode tab portion are on the same straight line.
[0042] Figure 3 This is a schematic diagram of a electrode unit whose height variation curve of the electrode tab is arranged in the shape of a convex function, which is provided by the present invention.
[0043] like Figure 3As shown, in some embodiments, the height change curve of the electrode tab is set as a convex function. The rate at which the height of the electrode tab increases decreases from left to right.
[0044] Figure 4 This is a schematic diagram of a electrode unit whose height variation curve of the electrode tab is arranged in a concave function shape, as provided by the present invention.
[0045] like Figure 4 As shown, in other embodiments, the height change curve of the electrode tab is arranged in a concave function shape. The height of the electrode tab increases at an increasing rate from left to right.
[0046] Figure 5 This is a schematic diagram of the structure of an electrode unit with a stepped height variation curve for the electrode tab provided by the present invention.
[0047] like Figure 5 As shown, in some other embodiments, the height variation curve of the electrode portion is set in a stepped manner.
[0048] It is worth noting that the slit is located at the point where the height of the tab changes abruptly.
[0049] Figure 6 This is a schematic diagram of a electrode unit with a wavy height variation curve for the electrode tab provided by the present invention.
[0050] like Figure 6 As shown, in some embodiments, the height change curve of the electrode portion is set in a wavy shape.
[0051] It is worth noting that the slit is located at the trough of the height of the tab.
[0052] Figure 7 This invention provides a schematic diagram of the structure of an electrode unit having a slit area and a reference area; like Figure 7 As shown, in some embodiments, the tab portion includes a slit area 1021 and a reference area 1022; the reference area 1022 is disposed between the slit area 1021 and the electrode portion; the slit is only disposed in the slit area 1021; the height of the reference area 1022 at both ends of the tab portion is set to B1 and B2 respectively; 0≦B1≦H1; 0≦B2≦H2.
[0053] In some embodiments, B1=0, B2=0; the tab portion includes only the slit area 1021.
[0054] In other embodiments, B1=H1, B2=H2; the tab portion includes only the reference region 1022.
[0055] In some other embodiments, B1=0, B2=H2; the minimum height of the tab portion includes only the slit area 1021, and the maximum height of the tab portion includes only the reference area 1022.
[0056] In some embodiments, B1=H1, B2=0; the minimum height of the tab portion includes only the reference area 1022, and the maximum height of the tab portion includes only the slit area 1021.
[0057] In some embodiments, the plurality of slits 103 are parallel to each other. The acute angle formed by the slits 103 and one side edge of the electrode portion 101 is greater than 0 degrees and less than 90 degrees. This arrangement facilitates the orderly flattening of the tab portion 102, reduces uneven stacking of the flattened tab portion 102, and ensures that both ends of the cylindrical cell are flat.
[0058] In some specific embodiments, the acute angle formed by the slit 103 and one side edge of the electrode portion 101 is 30 degrees.
[0059] In other specific embodiments, the acute angle formed by the slit 103 and one side edge of the electrode portion 101 is 45 degrees.
[0060] In some other embodiments, the acute angle formed by the slit 103 and one side edge of the electrode portion 101 is 60 degrees.
[0061] In some embodiments, at least one side of the tab 102 is provided with an active coating.
[0062] In some specific embodiments, one side of the tab portion 102 is provided with an active coating.
[0063] In other specific embodiments, both sides of the tab portion 102 are provided with an active coating.
[0064] Figure 8 This is a cross-sectional structural diagram of a wound cylindrical battery cell provided by the present invention.
[0065] like Figure 8 As shown, the present invention also provides a cylindrical battery cell, including a core winding module 100. The core winding module 100 includes a positive electrode unit 110 and a negative electrode unit 120 stacked together. Both the positive electrode unit 110 and the negative electrode unit 120 are configured as electrode units as described in any of the above embodiments. The core winding module 100 is spirally wound. The maximum height of the tabs 102 of the electrode units is located at the edge of the cylindrical battery cell, and the minimum height of the tabs 102 is located on the axial side of the cylindrical battery cell.
[0066] It is worth noting that when the core module 100 is wound in a spiral shape, the stacked positive electrode unit 110 and negative electrode unit 120 are wound together in a spiral shape. For example... Figure 8 As shown, the tab 102 of the negative electrode unit 120 is located at the top of the core module 100, and the tab 102 of the positive electrode unit 110 is located at the bottom of the core module 100.
[0067] In some embodiments, in the axial cross-section of the wound positive electrode unit 110 and negative electrode unit 120, the positive electrode unit 110 and negative electrode unit 120 are alternately stacked. The height of the tab portion 102 increases monotonically from the inside to the outside.
[0068] In some specific embodiments, the length of the negative electrode unit 120 is greater than the length of the positive electrode unit 110.
[0069] In some embodiments, the core module 100 forms a central hole 130.
[0070] Figure 9 This is a schematic diagram of an unfolded cylindrical battery cell provided by the present invention.
[0071] like Figure 9 As shown, in some embodiments, the manufacturing method of the cylindrical battery cell is as follows: the positive electrode unit 110 and the negative electrode unit 120 are spirally wound. The tab of the positive electrode unit 110 is flattened and welded to the positive current collector 111. The welded positive current collector 111 and the positive and negative electrode units are placed together into the encapsulation shell 140. An insulating sheet 113 is provided on the inner side of the top of the encapsulation shell 140; a positive electrode post 112 is riveted to the inner side of the positive electrode post 112. The positive electrode post 112 is welded to the positive current collector 111. The tab of the negative electrode unit 120 is flattened and welded to the negative current collector 122. The edge of the negative current collector 122 is welded to the bottom end of the encapsulation shell 140. Electrolyte is injected into the encapsulation shell 140 to form a cylindrical battery cell.
[0072] In some specific embodiments, the positive current collector 111 is located at the top of the cylindrical cell, and the negative current collector 121 is located at the bottom of the cylindrical cell.
[0073] In other specific embodiments, the negative current collector 121 is located at the top of the cylindrical cell, and the positive current collector 111 is located at the bottom of the cylindrical cell.
[0074] Figure 10 This is a schematic cross-sectional view of a cylindrical battery cell that is flattened after the tab is bent, as provided by the present invention.
[0075] like Figure 10As shown, in some other specific embodiments, after the tab 102 is bent, the tabs 102 at both ends of the core module 100 are all set to a flat shape.
[0076] In some embodiments, the cylindrical battery cell further includes a separator and a casing. The separator is disposed between the positive electrode unit 110 and the negative electrode unit 120. The casing completely surrounds the positive electrode unit 110 and the negative electrode unit 120. An electrolyte is disposed inside the casing.
[0077] In some specific embodiments, both the positive electrode unit 110 and the negative electrode unit 120 are immersed in the electrolyte.
[0078] In some specific embodiments, the number of separators is at least one. When the number of separators is set to one, the length of the separator is set to twice the length of the positive electrode unit 110. Alternatively, the length of the separator is set to twice the length of the negative electrode unit 120.
[0079] Figure 11 This is a schematic diagram of the electrode unit in Embodiment 1 of the present invention.
[0080] like Figure 11 and Figure 9 As shown, the present invention provides Embodiment 1: Both the positive electrode unit 110 and the negative electrode unit 120 are configured such that the height of the tab 102 monotonically decreases to 0 from the outside to the inside. The length of the tab 102 is equal to the length of the electrode portion 101. The positive electrode unit 110 and the negative electrode unit 120 are spirally wound. The tab of the positive electrode unit 110 is flattened and then welded to the positive current collector. The welded positive current collector 111 and the positive and negative electrode units are placed together into the encapsulation shell 140. An insulating sheet 113 is provided on the inner side of the top of the encapsulation shell 140; a positive electrode post 112 is riveted to the inner side of the positive electrode post 112. The positive electrode post 112 is welded to the positive current collector 111. The tab of the negative electrode unit 120 is flattened and then welded to the negative current collector 122. The edge of the negative current collector 122 is welded to the bottom of the package 140. Electrolyte is injected into the package to form a cylindrical battery cell.
[0081] Figure 12 This is a schematic diagram of the electrode unit in Embodiment 2 of the present invention.
[0082] like Figure 12 and Figure 9As shown, the present invention provides Embodiment 2: Both the positive electrode unit 110 and the negative electrode unit 120 are configured such that the height of the tab portion 102 decreases monotonically from the outside to the inside to 0. The length of the tab portion 102 is equal to the length of the electrode portion 101. The tab portion 102 is provided with slits 103 whose spacing decreases sequentially from the outside to the inside. The positive electrode unit 110 and the negative electrode unit 120 are spirally wound. The tab portion of the positive electrode unit 110 is flattened and then welded to the positive current collector. The welded positive current collector 111 and the positive and negative electrode units are placed together into the encapsulation shell 140. An insulating sheet 113 is provided on the inner side of the top of the encapsulation shell 140; a positive electrode post 112 is riveted to the inner side of the positive electrode post 112. The positive electrode post 112 is welded to the positive current collector 111. The tab of the negative electrode unit 120 is flattened and then welded to the negative current collector 122. The edge of the negative current collector 122 is welded to the bottom of the package shell 140. Electrolyte is injected into the package shell to form a cylindrical battery cell.
[0083] Figure 13 This is a schematic diagram of the electrode unit of Comparative Example 1 provided by the present invention.
[0084] like Figure 13 and Figure 9 As shown, the present invention provides Comparative Example 1: Both the positive electrode unit 110 and the negative electrode unit 120 are configured such that the height of the tab 102 remains constant from the outside to the inside. The length of the tab 102 is equal to the length of the electrode portion 101. The positive electrode unit 110 and the negative electrode unit 120 are spirally wound. The tab of the positive electrode unit 110 is flattened and then welded to the positive current collector. The welded positive current collector 111 and the positive and negative electrode units are placed together into the encapsulation shell 140. An insulating sheet 113 is provided on the inner side of the top of the encapsulation shell 140; a positive electrode post 112 is riveted to the inner side of the positive electrode post 112. The positive electrode post 112 is welded to the positive current collector 111. The tab of the negative electrode unit 120 is flattened and then welded to the negative current collector 122. The edge of the negative current collector 122 is welded to the bottom end of the encapsulation shell 140. Electrolyte is injected into the packaging shell to form a cylindrical battery cell.
[0085] Figure 14 This is a schematic diagram of the electrode unit of Comparative Example 2 provided by the present invention.
[0086] like Figure 14 and Figure 9As shown, the present invention provides Comparative Example 2: Both the positive electrode unit 110 and the negative electrode unit 120 are configured such that the height of the tab 102 remains constant from the outside to the inside. The length of the tab 102 is less than the length of the electrode portion 101. The tab 102 is provided with slits 103 with a constant spacing from the outside to the inside. The positive electrode unit 110 and the negative electrode unit 120 are spirally wound. The tab of the positive electrode unit 110 is flattened and then welded to the positive current collector. The welded positive current collector 111 and the positive and negative electrode units are placed together into the encapsulation shell 140. An insulating sheet 113 is provided on the inner side of the top of the encapsulation shell 140; a positive electrode post 112 is riveted to the inner side of the positive electrode post 112. The positive electrode post 112 is welded to the positive current collector 111. The tab of the negative electrode unit 120 is flattened and then welded to the negative current collector 122. The edge of the negative current collector 122 is welded to the bottom of the package 140. Electrolyte is injected into the package to form a cylindrical battery cell.
[0087] Based on the cylindrical battery cells prepared in Examples 1 and 2 and Comparative Examples 1 and 2 above, the maximum height of the edge of the core module, the minimum height of the inner side of the core module, the welding pull of the current collector, and the 7-day voltage drop were measured respectively.
[0088] It is worth noting that the maximum height of the edge of the core module and the minimum height of the inner side of the core module are both the cylindrical height of the tab 102 after bending.
[0089]
[0090] Observing Table 1, it can be seen that the maximum edge height of the core module in Examples 1 and 2 is lower than that of the core module in Comparative Examples 1 and 2. The minimum inner height of the core module in Examples 1 and 2 is lower than that of the core module in Comparative Examples 1 and 2. The welding pull force of the manifold in Examples 1 and 2 is greater than that in Comparative Examples 1 and 2. The 7-day voltage drop of Examples 1 and 2 is less than that in Comparative Examples 1 and 2. Furthermore, the welding pull force of the manifold in Example 2 is greater than that in Example 1.
[0091] It is readily apparent that in Examples 1 and 2, the height of the tab 102 decreases monotonically from the outside to the inside to 0, which helps to reduce the cylindrical height of the core, i.e., to reduce the required height of the cylindrical cell, and thus helps to increase the energy density of the cylindrical cell. By setting the length of the tab 102 to be equal to the length of the electrode portion 101, it helps to reduce the 7-day voltage drop of the cylindrical cell. By providing slits 103 with decreasing spacing from the outside to the inside in the tab 102, it helps to improve the welding pull of the current collector of the cylindrical cell, ensuring the impact resistance of the cylindrical cell.
[0092] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.
Claims
1. A cylindrical battery cell, characterized in that, The module includes a core module comprising stacked positive electrode units and negative electrode units, both of which are electrode units, and the core module is spirally wound; the electrode unit includes: The electrode portion and electrode tab portion are integrally set; The length of the electrode ear portion is not greater than the length of the electrode plate portion; Along the length direction of the electrode portion, the height of the electrode portion varies. The height of the electrode ear has a minimum value H1 and a maximum value H2, where H1 is less than H2, H1 is 0 or any positive number, and H2 is any positive number; The maximum height of the tab and the minimum height of the tab are located at opposite ends of the tab. The maximum height of the tab is located at the edge of the cylindrical cell, and the minimum height of the tab is located at the axial side of the cylindrical cell. The length relationship between the electrode portion and the electrode tab portion satisfies: L = L1 + L2 + L3; 0≦L1 / L≦1 / 15; 0 <L3 / L≦1 / 15; The length of the electrode portion is L, where L is any positive number. The distance from the maximum height of the electrode tab to the head end of the electrode portion is L1, where L1 is 0 or any positive number. The length of the electrode tab is L2, where L2 is any positive number. The distance from the maximum height of the electrode tab to the tail end of the electrode portion is L3, where L3 is any positive number. The electrode tab has several slits, which are distributed non-uniformly. The height variation curve of the electrode tab is wavy. The slits are located at the troughs of the height of the electrode tab, and the spacing between adjacent slits is proportional to the square of the height of the electrode tab.
2. The cylindrical battery cell according to claim 1, characterized in that, The plurality of slits are parallel to each other, and the acute angle formed by the slits and one side edge of the electrode portion is greater than 0 degrees and less than 90 degrees.
3. The cylindrical battery cell according to claim 1, characterized in that, The core module forms a central hole; the two ends of the cylindrical cell are respectively provided with a positive current collector and a negative current collector; The positive electrode post is welded to the positive current collector.
4. The cylindrical battery cell according to claim 3, characterized in that, The tabs of both the positive electrode unit and the negative electrode unit are bent toward the axis of the cylindrical cell. The positive current collector and the tab of the positive electrode unit are welded together; The negative electrode current collector and the tab of the negative electrode unit are welded together.
5. The cylindrical battery cell according to claim 3, characterized in that, The cylindrical battery cell also includes a separator and a packaging shell; The diaphragm is disposed between the positive electrode unit and the negative electrode unit; The encapsulation shell is located outside the positive current collector, the positive electrode unit, and the negative electrode unit; The encapsulation shell contains an electrolyte.