Battery cells and cylindrical batteries

Abstract

This utility model relates to a battery cell and a cylindrical battery. The tab area includes a flattened tab area and a rolled-up tab area, with the rolled-up tab area located on the inner ring of the battery cell compared to the flattened tab area. The rolled-up tab area has a larger stacked thickness after the entire tab is rolled up, while the stacked thickness of the multiple individual tabs in the flattened tab area after bending is smaller. Therefore, even if the height of the rolled-up tab area is less than that of the flattened tab area, its stacked thickness can still meet welding requirements and has a small difference from the stacked thickness of the flattened tab area. Thus, the weld mark formed by welding can extend from the inner ring to the outer ring of the battery cell, thereby increasing the area of ​​the weldable region and reducing the internal resistance of the battery cell. Moreover, the reduced overall thickness of the tab area also improves space utilization. It is evident that the above-mentioned battery cell and cylindrical battery can combine the advantages of both tab flattening and tab rolling processes, ensuring energy density while reducing internal resistance.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to a battery cell and a cylindrical battery. Background Technology

[0002] In the assembly of cylindrical batteries, two different process routes are generally selected: tab flattening and tab pressing. When using tab pressing, to prevent clogging the center hole, the height of the inner tabs is smaller than that of the outer tabs. Therefore, the height of the tabs after flattening varies along the radial direction of the cell, resulting in a smaller weldable area for welding to the current collector, thus increasing the cell's internal resistance. Conversely, when using tab flattening, the weldable area after flattening is larger than with the pressing method. However, to ensure the flatness of the tab end face and the welding effect, the height of the tabs increases significantly, leading to reduced space utilization and consequently a loss of energy density. Utility Model Content

[0003] Therefore, it is necessary to provide a cell and cylindrical battery that can reduce internal resistance while ensuring energy density, in order to address the above problems.

[0004] A battery cell includes an electrode sheet, the electrode sheet including a tab region and a coating region, the tab region including a flattened tab region and a smoothed tab region arranged side by side along the length direction of the electrode sheet, the flattened tab region forming a plurality of single tabs arranged along the length direction of the electrode sheet, the smoothed tab region forming a full tab, and the height of the smoothed tab region being less than the height of the flattened tab region;

[0005] The electrode sheet is wound into a column shape, the tab area is bent and stacked on the end face of the battery cell, and the flattened tab area is farther away from the center of the battery cell than the kneaded tab area.

[0006] In one embodiment, the flattened tab area extends from the winding end of the electrode sheet to the middle, and the kneaded tab area extends from the end of the flattened tab area away from the winding end to the winding start end of the electrode sheet.

[0007] In one embodiment, the length of the flattened tab area is L1, and the length of the kneaded tab area is L2, where L2 = (1 / 20 ~ 1 / 5)L1.

[0008] In one embodiment, the height of the flattened tab area is H1, and the height of the kneaded tab area is H2, wherein H2 = (0.2~0.5)H1.

[0009] In one embodiment, the stacking thickness of the flattened tab region is H3, and the stacking thickness of the kneaded tab region is H4, wherein H3-H4=△T2, and △T2=0.05mm to 0.7mm.

[0010] In one embodiment, the flattened tab area is formed with a groove extending along the length of the electrode sheet.

[0011] In one embodiment, a chamfer is formed at at least one apex corner of each of the monopole ears.

[0012] A cylindrical battery includes a casing, a current collector, and a cell as described in any of the preferred embodiments above, wherein the cell is housed within the casing, and the current collector is welded to the tab region.

[0013] In one embodiment, the radius of the busbar is R1, and the dimension of the solder mark between the busbar and the tab area in the radial direction of the cell is L3, where L3 = (0.8~0.95)R1.

[0014] In one embodiment, the current collector has a protrusion on the side facing the battery cell, and the protrusion abuts against the flattened tab area.

[0015] The aforementioned battery cells and cylindrical batteries include a flattened tab area and a rolled-up tab area, with the rolled-up tab area located on the inner ring of the cell. The rolled-up tab area has a larger stacked thickness after the entire tab is rolled up, while the stacked thickness of the multiple individual tabs in the flattened tab area is smaller after bending. Therefore, even if the height of the rolled-up tab area is less than that of the flattened tab area, its stacked thickness can still meet welding requirements and is only slightly different from the stacked thickness of the flattened tab area. Thus, the weld marks formed by welding can extend from the inner ring to the outer ring of the cell, thereby increasing the area of ​​the weldable region and reducing the internal resistance of the cell. Furthermore, the reduced overall thickness of the tab area also improves space utilization. It is evident that the aforementioned battery cells and cylindrical batteries can combine the advantages of both tab flattening and tab rolling processes, ensuring energy density while reducing internal resistance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the assembly of the cell and current collector of a cylindrical battery in one embodiment of the present invention.

[0018] Figure 2 This is a top view of the battery cell in one embodiment of the present invention;

[0019] Figure 3 for Figure 2 The cell shown is a cross-sectional view along AA.

[0020] Figure 4 for Figure 2 A schematic diagram of the unfolded electrode sheet in the battery cell shown.

[0021] Figure 5 for Figure 4 The diagram shows the electrode after winding.

[0022] Figure 6 This is a schematic diagram of the structure of the electrode sheet after unfolding in another embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the structure of the electrode sheet after unfolding in one embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of the assembly of the battery cell and the current collector in another embodiment of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0026] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0031] Please see Figure 1 This utility model provides a cylindrical battery and a battery cell 10. The cylindrical battery includes a battery cell 10, a current collector 20, and a casing (not shown).

[0032] The casing has a cylindrical structure, specifically a cylindrical shape, and can be made of aluminum or steel. The battery cell 10 and the current collector 20 are housed within the casing. The casing can be a hollow structure with one open end, through which the battery cell 10 and the current collector 20 can be installed, and the opening is sealed by a cover plate (not shown) after assembly. The battery cell 10 is generally cylindrical and has a positive tab and a negative tab; the current collector 20 includes a positive current collector and a negative current collector; the cover plate generally also has terminals. The positive tab of the battery cell 10 is welded to the terminal through the positive current collector, while the negative tab is welded to the casing through the negative current collector. Therefore, the terminals and the casing can serve as the positive and negative output terminals of the cylindrical battery, respectively.

[0033] Of course, the casing can also be open at both ends, so two cover plates are required, and the positive and negative terminals are respectively insulated on the two cover plates. The positive and negative tabs of the cell 10 are welded to the positive and negative terminals through the positive current collector and the negative current collector, respectively. Therefore, the positive and negative terminals will serve as the positive and negative output terminals of the cylindrical battery.

[0034] Please refer to the following: Figure 2 , Figure 3 and Figure 4 In one embodiment of this utility model, the battery cell 10 includes an electrode 100, which is wound into a cylindrical shape. The electrode 100 used to prepare the battery cell 10 includes both positive and negative electrode plates, and adjacent electrode plates 100 are separated by a separator (not shown). Each battery cell 10 includes at least one positive electrode plate and one negative electrode plate.

[0035] Each electrode 100 includes a tab region 110 and a coating region 120. The tab region 110 is generally located on one side of the coating region 120 in the width direction. The coating region 120 is coated with electrode material, while the tab region 110 is not coated to expose the foil. The tab region 110 of the positive electrode ultimately forms the positive tab of the battery cell 10, while the tab region 110 of the negative electrode ultimately forms the negative tab of the battery cell 10. The foil of the positive electrode is generally aluminum foil, and its coating region 120 is coated with a positive electrode material, such as lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide; while the foil of the negative electrode is generally copper foil, and its coating region 120 is coated with a negative electrode material, such as graphite.

[0036] Furthermore, the tab region 110 includes a flattened tab region 111 and a smoothed tab region 112, which are arranged side by side along the length of the electrode sheet 100. Moreover, the flattened tab region 111 forms multiple monopole tabs 111a arranged along the length of the electrode sheet 100, while the smoothed tab region 112 constitutes a full tab. Specifically, the flattened tab region 111 can be cut into multiple closely arranged monopole tabs 111a by slit cutting, or a portion of the material can be removed to cut the flattened tab region 111 into multiple more spaced monopole tabs 111a; the smoothed tab region 112 does not need to be cut, thus forming a single tab, i.e., a full tab.

[0037] Furthermore, the height of the flattened tab area 112 is less than the height of the flattened tab area 111. The height of the tab area 110 refers to the distance between the edge of the tab area 110 away from the coating area 120 and the coating area 120 when the electrode sheet 100 is in the unfolded state.

[0038] like Figure 5 As shown, after the electrode 100 is wound into a cylindrical shape, the flattened tab area 111 and the flattened tab area 112 are also wound into a ring. The flattened tab area 111 is located on the outer ring along the radial direction of the cell 10, while the flattened tab area 112 is located on the inner ring. After the tab area 110 is shaped, it is bent and stacked on the end face of the cell 10, and the flattened tab area 111 is farther from the center of the cell than the flattened tab area 112. That is, the flattened tab area 112 is distributed near the starting end of the winding of the electrode 100, while the flattened tab area 111 is distributed near the ending end of the winding of the electrode 100. The starting end of the winding of the electrode 100 refers to the end located inside the cell 10 after being wound into the cell 10, while the ending end refers to the end located outside the cell 10.

[0039] More specifically, a flattening process can be used to stack the flattened tab area 111 onto the end face of the cell 10, and a flattening and kneading process can be used to stack the flattened tab area 112 onto the end face of the cell 10. After flattening and kneading, the tab area 110 is stacked on the surface of the cell 10, and the current collector 20 is welded to the tab area 110 stacked on the end face of the cell 10 to form a solder mark 30.

[0040] The flattened tab region 112 has a larger stack thickness after flattening, while the multiple single tabs in the flattened tab region 111 have a smaller stack thickness after bending. Therefore, even though the height of the flattened tab region 112 is smaller, its stack thickness after flattening is sufficient for welding requirements. Moreover, since the height of the flattened tab region 112 is smaller than that of the flattened tab region 111, the difference in stack thickness between the flattened tab region 111 and the flattened tab region 112 is smaller, and the thickness distribution of the tab region 110 along the radial direction of the cell 10 is more uniform. Therefore, the solder mark 30 formed by welding the current collector 20 and the tab region 110 can extend from the inner ring to the outer ring of the cell 10, thereby increasing the area of ​​the solderable region to achieve the purposes of reducing the internal resistance of the cell 10, reducing polarization, and improving cycle performance.

[0041] Furthermore, since only a portion of the tab area 110 is flattened tab area 112, only partial flattening is required during the cell 10 forming process. This significantly reduces the overall thickness of the tab area 110 compared to overall flattening, thereby reducing the height of the cell 10 and improving space utilization. Moreover, the debris generated by partial flattening is correspondingly less and easier to manage, thus reducing the probability of debris entering the cell 10 and causing self-discharge problems. The larger gaps after flattening the tab area 111 also improve the wetting effect. Therefore, the aforementioned cell 10 combines the advantages of both tab flattening and tab rolling processes.

[0042] Specifically, in this embodiment, the flattened tab area 111 extends from the winding end of the electrode sheet 100 to the middle, and the flattened tab area 112 extends from the end of the flattened tab area 111 away from the winding end to the winding start end of the electrode sheet 100. It can be seen that the flattened tab area 111 and the flattened tab area 112 are closely arranged, with little or no gap between them, thereby enabling the tab areas 110 to be stacked more uniformly on the end face of the cell 10.

[0043] In this embodiment, the length of the flattened tab area 111 is L1, and the length of the smoothed tab area 112 is L2, where L2 = (1 / 20 to 1 / 5)L1, for example, L2 = 1 / 20L1, L2 = 1 / 8L1, and L2 = 1 / 5L1. If L2 is less than 1 / 20 of L1, the smoothed tab area 112 is too short, which is equivalent to increasing the length of the flattened tab area 111, thus increasing the risk of the flattened tab area 111 blocking the center hole of the cell 10 after being flattened; if L2 is greater than 1 / 5 of L1, the smoothed tab area 112 is too long, and the area of ​​the locally smoothed area will increase, thereby increasing the height of the cell 10 and increasing the risk of debris entering the cell 10.

[0044] In this embodiment, the height of the flattened tab area 111 is H1, and the height of the kneaded tab area 112 is H2, where H2 = (0.2~0.5)H1, for example, H2 = 0.2H1, H2 = 0.35H1, H2 = 0.5H1. Specifically, H1 is generally set to 6mm to 15mm, and H2 is generally set to 3mm to 7mm. Setting H2 within the range of (0.2~0.5)H1 maximizes the advantages of both the kneading and flattening processes.

[0045] In this embodiment, the stacking thickness of the flattened tab area 111 is H3, and the stacking thickness of the flattened tab area 112 is H4, wherein H3-H4=△T2, and △T2=0.05mm to 0.7mm. Preferably, △T2=0.2mm to 0.5mm. If △T2 is too large, the flatness of the end face of the cell 10 will be poor, resulting in poor welding effect. Moreover, the flattened tab area 112 located in the inner ring cannot be effectively flattened.

[0046] In this embodiment, the radius of the current collector 20 is R1, and the radial dimension of the solder joint 30 between the current collector 20 and the tab area 110 is L3, where L3 = (0.8~0.95)R1, for example, L3 = 0.8R1, L3 = 0.87R1, L3 = 0.95R1. It can be seen that the solder joint 30 can almost cover the entire surface of the current collector 20, thereby generating solder joints with the tab area 110 from the inner ring to the outer ring on the end face of the cell 10.

[0047] In addition, please see Figure 7 In one embodiment, the flattened tab area 112 is formed with a groove 1121 extending along the length of the electrode sheet 100. Specifically, the groove 1121 can be formed in the flattened tab area 112 by operations such as rolling. Moreover, the groove 1121 can guide the flattened tab area 112 to bend during the subsequent flattening process, thereby improving the flattening effect and making the stacking thickness distribution of the flattened tab area 112 on the end face of the cell 10 more uniform. In addition, the groove 1121 can also cause the flattened tab area 112 to gather inward in advance, preventing it from deforming and squeezing outward and affecting the flattening operation of the flattened tab area 111.

[0048] Please see Figure 6 In one embodiment, a chamfer 111b is formed at at least one apex corner of each monopole 111a. After the monopole area 111 is flattened, each ring of monopole 111a can be approximately formed as a circle (e.g., Figure 2(As shown). In each ring of monopole 110a, adjacent monopole 110a overlaps, and the closer to the inner ring, the larger the overlapping area between adjacent monopole 110a, resulting in greater interference and a worse flattening effect. By forming a chamfer 111b at the apex of the monopole 111a, interference can be reduced, thereby improving the shaping effect on the flattening area 111.

[0049] In addition, please see Figure 8 In one embodiment, the current collector 20 has a protrusion 210 on the side facing the battery cell, and the protrusion 210 abuts against the flattened tab area 112.

[0050] After the flattening and smoothing operations, the tab area 110 may rebound, especially the flattened tab area 112, which has a higher rebound rate. By setting a protrusion 210 to abut against the flattened tab area 112, the rebound of the flattened tab area 112 can be effectively prevented, thereby ensuring that the tab areas 110 can be stacked in an orderly manner on the end face of the cell 10, ensuring the consistency of its welding with the current collector 20. Specifically, the protrusion 210 can be annular to match the shape of the wound flattened tab area 112. The protrusion 210 can be a continuous annular shape or a discontinuous annular shape with a gap in the middle.

[0051] The protrusion 210 can be integrally formed with the busbar 20. Specifically, the protrusion 210 protruding towards the battery cell 10 can be formed by locally thickening the inner surface of the busbar 20 facing the battery cell 10; alternatively, the outer surface of the busbar 20 facing away from the battery cell 10 can be stamped to form a recess on the outer surface while simultaneously forming the protrusion 210 protruding towards the battery cell on the inner surface. The protrusion 210 is typically positioned to avoid the solder mark 30 to ensure that the solder interface remains flat in the radial direction of the battery cell 10.

[0052] The aforementioned battery cell 10 and cylindrical battery have a tab region 110 comprising a flattened tab region 111 and a rolled-up tab region 112. The rolled-up tab region 112 is located within the inner ring of the battery cell, compared to the flattened tab region 111. The rolled-up tab region 112 has a larger stack thickness after the tabs are rolled up, while the multiple single tabs 111a of the flattened tab region 111 have a smaller stack thickness after bending. Therefore, even if the height of the rolled-up tab region 112 is less than the height of the flattened tab region 111, its stack thickness can still meet the welding requirements and has a small difference from the stack thickness of the flattened tab region 111. Thus, the weld mark 30 formed by welding can extend from the inner ring to the outer ring of the battery cell 10, thereby increasing the area of ​​the weldable region and reducing the internal resistance of the battery cell 10. Furthermore, the reduced overall thickness of the tab region 110 also improves space utilization. It is evident that the aforementioned cell 10 and cylindrical battery can combine the advantages of both tab flattening and tab rolling processes, reducing internal resistance while ensuring energy density.

[0053] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A battery cell, comprising an electrode sheet, said electrode sheet including a tab region and a coating region, characterized in that, The tab area includes a flattened tab area and a kneaded tab area arranged side by side along the length direction of the electrode sheet. The flattened tab area forms multiple single tabs arranged along the length direction of the electrode sheet. The kneaded tab area constitutes a full tab, and the height of the kneaded tab area is less than the height of the flattened tab area. The electrode sheet is wound into a column shape, the tab area is bent and stacked on the end face of the battery cell, and the flattened tab area is farther away from the center of the battery cell than the kneaded tab area.

2. The battery cell according to claim 1, characterized in that, The flattened tab area extends from the winding end of the electrode sheet to the middle, and the kneaded tab area extends from the end of the flattened tab area away from the winding end to the winding start end of the electrode sheet.

3. The battery cell according to claim 1, characterized in that, The length of the flattened tab area is L1, and the length of the kneaded tab area is L2, where L2 = (1 / 20 ~ 1 / 5)L1.

4. The battery cell according to claim 1, characterized in that, The height of the flattened tab area is H1, and the height of the kneaded tab area is H2, where H2 = (0.2~0.5)H1.

5. The battery cell according to claim 1, characterized in that, The stacking thickness of the flattened tab area is H3, and the stacking thickness of the kneaded tab area is H4, wherein H3-H4=△T2, and △T2=0.05mm to 0.7mm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The flattened tab area has a groove extending along the length of the electrode sheet.

7. The battery cell according to any one of claims 1 to 5, characterized in that, Each of the monopole ears has a chamfer at at least one apex corner.

8. A cylindrical battery, characterized in that, It includes a housing, a current collector, and a battery cell as described in any one of claims 1 to 7, wherein the battery cell is housed within the housing, and the current collector is welded to the tab region.

9. The cylindrical battery according to claim 8, characterized in that, The radius of the busbar is R1, and the dimension of the solder mark between the busbar and the tab area in the radial direction of the cell is L3, where L3 = (0.8~0.95)R1.

10. The cylindrical battery according to claim 8, characterized in that, The current collector has a protrusion on the side of its surface facing the battery cell, and the protrusion abuts against the flattened tab area.

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