Positive electrode confluence plate and single battery

Abstract

The utility model relates to an anode confluence plate and a single battery, belongs to the technical field of cylindrical batteries, and solves the problems of poor stress release capability, poor exhaust capability, insufficient electrolyte channels and the like of the anode confluence plate in the prior art. The utility model provides a positive pole confluence plate which comprises a body part and a connecting part, the body part is provided with a first through hole and a second through hole which penetrate through the body part, the body part is in a superior arch shape, the first through hole is formed in the center of the body part, and the second through hole is formed around the first through hole; the connecting part is connected with one end of the body part; the total area of the positive collector plate is S, the area of the first through hole is S1, and the total area of the second through hole is S2; 1 / 12 < = (S1 + S2) / S < = 1 / 6. The positive electrode confluence plate can effectively release stress generated during laser welding, provides a channel for electrolyte discharging and gas discharging, and remarkably improves the service life and the safety performance of the battery.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical battery technology, and in particular to a positive electrode busbar and a single battery cell. Background Technology

[0002] Currently, cylindrical batteries are gradually becoming the mainstream product in the new energy industry due to their advantages such as high energy density, good capacity consistency, and ability to support high-rate charging and discharging. More and more manufacturers are continuously pursuing the optimization of cylindrical battery structure compactness to improve energy density.

[0003] As an important structural component of cylindrical batteries, the busbar serves to collect current and output it to the outside. One end of the positive busbar is connected to the battery's tab inside, and the other end is connected to the positive terminal outside, used to transmit the energy inside the battery.

[0004] Existing positive electrode busbars have drawbacks such as poor stress release capability, poor venting capability, and insufficient electrolyte channels, which can lead to a shortened lifespan of individual cells and a decline in safety performance. Utility Model Content

[0005] Based on the above analysis, the present invention aims to provide a positive electrode busbar for cylindrical batteries to solve at least one of the problems of poor stress release capability, poor venting capability, and insufficient electrolyte channels in existing positive electrode busbars.

[0006] The objective of this utility model is mainly achieved through the following technical solutions:

[0007] This utility model provides a positive electrode busbar, comprising:

[0008] The body portion 42 has a first through hole 43 and a second through hole 44 penetrating the body portion 42. The body portion 42 is arc-shaped. The first through hole 43 is located at the center of the body portion 42, and the second through hole 44 is arranged around the first through hole 43.

[0009] The connecting part 41 is connected to one end of the main body part 42;

[0010] Wherein, the total area of ​​the positive electrode busbar 4 is S, the area of ​​the first through hole 43 is S1, and the total area of ​​the second through hole 44 is S2; 1 / 12≤(S1+S2) / S≤1 / 6.

[0011] In the above technical solution, by setting a first through hole and a second through hole on the body of the positive electrode busbar, and limiting the ratio of the sum of the areas of the first through hole and the second through hole to the total area of ​​the positive electrode busbar to more than 1 / 12, the overall strength of the positive electrode busbar can be guaranteed. When welding with the electrode assembly, welding stress can be better released, and failure is less likely. Limiting the ratio to less than 1 / 6 can guarantee the through hole area, resulting in higher liquid injection efficiency and better wetting effect of the electrode assembly. During battery cycling, the through hole can discharge the gas generated by the internal reaction, avoiding expansion caused by gas inside the electrode assembly, making the battery safer.

[0012] Preferably, 1 / 10 ≤ (S1 + S2) / S ≤ 1 / 8. This setting can ensure the strength of the positive electrode busbar while improving the liquid injection efficiency and venting capacity.

[0013] Preferably, the connecting portion 41 is rectangular, and the connecting portion 41 is connected to the chord of the body portion 42 and extends radially outward.

[0014] Preferably, the first through hole 43 is circular with a diameter of 5-6 mm.

[0015] Preferably, the second through hole 44 can be one or more of the following: triangle, square, rectangle, trapezoid, sector, circle, ellipse or irregular polygon.

[0016] Preferably, when the second through hole 44 is circular, the diameter of the second through hole 44 is 1 to 4 mm.

[0017] Preferably, the number of the second through holes 44 is ≥2 and they are evenly distributed around the first through hole 43 in the circumferential direction. While ensuring the structural strength of the positive electrode busbar, appropriately increasing the number of the second through holes 44 and ensuring their even distribution helps to improve the electrolyte injection efficiency and venting efficiency of the battery.

[0018] This utility model also discloses a single-cell battery, comprising:

[0019] Housing 7, the housing 7 including a cylindrical receiving cavity with an opening;

[0020] Cap assembly 2 is placed on the housing 7 to close the opening;

[0021] An electrode assembly, comprising a bare cell 5 formed by winding a positive electrode sheet, a separator, and a negative electrode sheet;

[0022] The positive electrode busbar 4 is also mentioned; the connecting part 41 is connected to the cap assembly 2; and the body part 42 is connected to the electrode assembly.

[0023] In the battery solution described above, the welding process for the busbar is simpler and the welding stability is better during battery assembly.

[0024] Preferably, the battery further includes a second insulating pad 3; the second insulating pad is provided with a third through hole, and the connecting part 41 passes through the third through hole to connect with the cap assembly 2. The second insulating pad can insulate the positive electrode busbar body 42 from the cap.

[0025] Preferably, the thickness of the positive electrode busbar 4 is h1, and the height of the electrode assembly is h2, with h2:h1 being (333~666):1. Limiting the height of the electrode assembly and the thickness of the positive electrode busbar to this ratio ensures the overall strength and current carrying capacity of the positive electrode busbar while reducing its footprint within the battery, thus minimizing its impact on battery energy density. It also improves welding pull-charge rate capability and cycle life.

[0026] Preferably, the main body 42 is connected to the positive electrode tab of the electrode assembly by laser welding, and the connecting part 41 is connected to the cap assembly 2 by laser welding.

[0027] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or be learned by practicing this invention. The objectives and other advantages of this invention can be realized and obtained from the details specifically pointed out in the text and accompanying drawings. Attached Figure Description

[0028] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0029] Figure 1 This is a schematic diagram of a possible positive electrode busbar structure;

[0030] Figure 2 This is a schematic diagram of the structure and assembly of a single cylindrical battery cell.

[0031] Figure 3 This is a partially enlarged view of the structural and assembly diagram of a single cylindrical battery cell;

[0032] Figure 4 This is a schematic diagram of a possible positive electrode busbar structure.

[0033] Figure label:

[0034] 1. First insulating pad; 2. Cap assembly; 3. Second insulating pad; 4. Positive busbar; 5. Bare battery cell; 6. Negative busbar; 7. Housing; 41. Connecting part; 42. Body part; 43. First through hole; 44. Second through hole. Detailed Implementation

[0035] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0036] like Figure 1 The diagram illustrates a positive electrode busbar according to one embodiment of this application, comprising: a body portion 42 and a connecting portion 41, the body portion being connected to the connecting portion; the body portion 42 is provided with a first through hole 43 penetrating the body portion and a plurality of second through holes 44, the body portion being bow-shaped, the first through hole being located at the center of the body portion, and the second through holes being arranged around the first through hole; the connecting portion is rectangular, the connecting portion being connected to the chord of the body portion and extending radially outward. The total area of ​​the positive electrode busbar, i.e., the total area of ​​the body portion 42 and the connecting portion 41, is S, the area of ​​the first through hole is S1, and the total area of ​​the plurality of second through holes is S2; satisfying 1 / 12≤(S1+S2) / S≤1 / 6, for example, a point value of any one of 1 / 12, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, or a range between any two. Limiting the ratio of the sum of the areas of the first and second through holes to the total area of ​​the positive electrode busbar to more than 1 / 12 ensures the overall strength of the positive electrode busbar and allows for better release of welding stress during welding with the electrode assembly, reducing the risk of failure. Limiting the ratio to less than 1 / 6 ensures the through hole area, resulting in higher liquid injection efficiency and better wetting of the electrode assembly. During battery cycling, the through holes can release gases generated by internal reactions, preventing expansion caused by gases inside the electrode assembly and enhancing battery safety.

[0037] In some embodiments, the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy 1 / 10 ≤ (S1 + S2) / S ≤ 1 / 8, for example, a point value of any one of 1 / 10, 1 / 9, or 1 / 8, or a range between any two. This configuration ensures the strength of the positive electrode busbar while improving liquid injection efficiency and venting capability.

[0038] In some embodiments, the central angle corresponding to the superior arc shape is in the range of 210 to 270°, for example, it is any one of 210°, 215°, 220°, 225°, 230°, 235°, 240°, 245°, 250°, 255°, 260°, 265°, 270° or any range between two of them. Because a central angle that is too small is not conducive to the stability of laser welding, and a central angle that is too large is not conducive to the stress release of the joint.

[0039] Furthermore, in some embodiments, the length l and width d of the connecting portion should satisfy the following conditions: 1 / d = 1:1 to 3:1 and the width d does not exceed the chord length of the superior bow shape.

[0040] Furthermore, in some embodiments, the first through hole is circular with a diameter of 5-6 mm.

[0041] Furthermore, in some embodiments, the second through hole is one or more of the following shapes: triangle, square, rectangle, trapezoid, sector, circle, ellipse, or irregular polygon; when the second through hole is circular, the diameter of the second through hole is 1 to 4 mm.

[0042] Furthermore, in some embodiments, the number of second through holes is ≥2 and they are evenly distributed around the first through hole in a circumferential direction, for example, 2, 3, 4, 5, 6, 7, 8. Figure 4 The number of second through holes shown is 4, as follows: Figure 1 The number of second through holes shown is three. This arrangement, while ensuring the structural strength of the positive electrode busbar, appropriately increases the number of second through holes and distributes them evenly, which helps to improve the electrolyte injection efficiency and venting efficiency of the battery.

[0043] like Figure 2 As shown, an embodiment of this utility model also discloses a single-cell battery, including: a housing 7, an electrode assembly, a cap assembly 2; and a positive electrode busbar 4; the housing includes a cylindrical receiving cavity with an opening; the cap assembly is placed on the housing to close the opening; the electrode assembly includes a bare cell 5 formed by winding a positive electrode sheet, a separator, and a negative electrode sheet; the connecting part 41 of the positive electrode busbar is connected to the cap assembly; and the body part 42 is connected to the electrode assembly. During battery assembly, the body part of the busbar is welded to the positive electrode tab of the electrode assembly. After bending the body part, the electrode assembly with the busbar welded on is inserted into the housing. After liquid injection, the connecting part is welded to the cap. This structure makes the battery welding process easier to operate. Compared with welding the positive electrode busbar body to the electrode assembly and the cap separately, its welding stability is better; and because the body part is provided with through holes, the liquid injection efficiency is higher, the electrode assembly is better wetted, and the battery performance is better.

[0044] In some embodiments, the single cell further includes a first insulating pad 1, which is an annular insulating sheet disposed on the cap to insulate the battery cap.

[0045] In some embodiments, the single battery cell also includes a negative electrode busbar 6, which is used for negative electrode busbars, with one side connected to the negative electrode of the battery assembly 5 and the other side connected to the bottom of the housing 7.

[0046] In some embodiments, the individual battery cell further includes a second insulating pad 3, such as Figure 3 As shown, the second insulating pad has a third through hole, through which the connecting part 41 passes and connects to the cap assembly. The second insulating pad insulates the positive electrode busbar body from the cap, improving battery safety.

[0047] In some embodiments, the thickness of the positive electrode busbar of a single cell is h1, and the height of the electrode assembly is h2, where h2:h1 is (333~666):1. For example, it can be a point value or a range between any one of 333, 350, 400, 450, 500, 550, 600, 650, and 666. By limiting the total area of ​​the through holes on the positive electrode busbar and the thickness of the positive electrode busbar, the current-carrying capacity of the busbar and the strength of the positive electrode busbar can be guaranteed while reducing the impact of the space occupied by the positive electrode busbar inside the battery on the battery's energy density. It can also improve the welding pull-charge rate capability and cycle life.

[0048] In some embodiments, the positive electrode busbar body is connected to the positive electrode tab of the electrode assembly of the single cell by laser welding, and the positive electrode busbar connection part is connected to the single cell cap assembly by laser welding.

[0049] Example 1

[0050] refer to Figure 4 A positive electrode busbar is prepared, which includes a body part 42 and a connecting part 41. The body part is provided with a first through hole 43 and a second through hole 44. The number of second through holes is 4. The total area of ​​the positive electrode busbar is marked as S, the area of ​​the first through hole is marked as S1, and the total area of ​​the second through hole is marked as S2. Wherein, (S1+S2) / S=1 / 4.

[0051] refer to Figure 3The single-cell battery structure is fabricated using a positive electrode busbar. The positive electrode busbar body is laser-welded to the positive electrode assembly, and the negative electrode tab of the electrode assembly is welded to the negative electrode busbar. The connecting part of the positive electrode return plate is bent, and then the electrode assembly with the welded positive and negative electrode busbars is inserted into the casing. The negative electrode return plate is then laser-welded to the bottom of the casing. The single-cell battery undergoes insulation testing, baking, electrolyte filling, and immersion. The cap is then welded to the connecting part of the positive electrode busbar, and the battery is sealed. Finally, the battery undergoes encapsulation, heat shrink molding, settling, formation, capacity testing, and sorting to obtain the single-cell battery.

[0052] Example 2

[0053] Compared with Example 1, the difference is that the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy (S1+S2) / S=1 / 6.

[0054] Example 3

[0055] Compared with Example 1, the difference is that the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy (S1+S2) / S=1 / 8.

[0056] Example 4

[0057] Compared with Example 1, the difference is that the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy (S1+S2) / S=1 / 10.

[0058] Example 5

[0059] Compared with Example 1, the difference is that the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy (S1+S2) / S=1 / 12.

[0060] Example 6

[0061] Compared with Example 1, the difference is that the total area S of the positive electrode busbar, the area S1 of the first through hole, and the total area S2 of the second through hole satisfy (S1+S2) / S=1 / 14.

[0062] Hot box safety test, poor soldering rate test and liquid injection efficiency test were performed on Examples 1-6.

[0063] The cold solder joint test refers to a destructive test performed on the welded position after laser welding. The proportion of solder joint area <70%, preferably <0.5%, is considered better. The smaller the solder joint area, the better the welding effect and the better the stability of the single cell.

[0064] Liquid injection efficiency is statistically tested during the preparation of single cells. It refers to the number of cells that are injected with liquid per minute. There should be no defects such as floating liquid or leakage. The preferred efficiency is >10ppm.

[0065] The hot box safety test method refers to the national standard GB 38031 8.1.5. The preferred test result is that the single cell that passes the test is safer.

[0066] The test results of Examples 1-6 are shown in Table 1.

[0067] Table 1

[0068]

[0069] As shown in Table 1, when the ratio of the area of ​​the positive electrode busbar to the area of ​​the through hole, S / (S1+S2), satisfies S / (S1+S2) = 6 to 12:1, the test results are excellent. When the ratio of the area of ​​the positive electrode busbar to the area of ​​the through hole, S / (S1+S2), is too small or too large, the overall test results are poor.

[0070] Specifically, when the area of ​​S1+S2 is too large, it will affect the welding stress, which will increase the rate of poor soldering of the positive electrode busbar.

[0071] When the area of ​​S1+S2 is too small, it will affect the welding stress, liquid injection effect and venting effect, which will reduce the welding pull force and liquid injection efficiency of the positive electrode busbar, and at the same time, it will fail the hot box safety test (related to venting safety performance).

[0072] In summary, within the preferred area ratio S / (S1+S2) = 6 to 12:1, the overall strength of the positive electrode busbar can be guaranteed, while the liquid injection efficiency can be improved and the hot box safety test can be passed; the false soldering rate is ≤0.3% and the liquid injection efficiency is ≥12ppm.

[0073] Example 7

[0074] This embodiment further defines the structure of the positive electrode busbar based on embodiment 3. The thickness of the positive electrode busbar is marked as h1. In this embodiment, the thickness of the positive electrode busbar refers to the thickness of the body of the positive electrode busbar. The height of the electrode assembly is marked as h2, which satisfies h2:h1=267:1.

[0075] Example 8

[0076] Compared with Example 7, the difference is that the thickness of the positive electrode busbar h1 and the height of the electrode assembly h2 satisfy h2:h1=267:1.

[0077] Example 9

[0078] Compared with Example 7, the difference is that the thickness of the positive electrode busbar h1 and the height of the electrode assembly h2 satisfy h2:h1=267:1.

[0079] Example 10

[0080] Compared with Example 7, the difference is that the thickness of the positive electrode busbar h1 and the height of the electrode assembly h2 satisfy h2:h1=267:1.

[0081] Example 11

[0082] Compared with Example 7, the difference is that the thickness of the positive electrode busbar h1 and the height of the electrode assembly h2 satisfy h2:h1=267:1.

[0083] Examples 7-11 were subjected to positive electrode busbar welding tensile test, capacity retention test, and cycle life test.

[0084] The cold solder joint test refers to the destructive test performed on the welded position after the positive electrode tab of the electrode assembly is laser welded to the positive electrode busbar body. The weld pull force is collected, preferably >12N. The greater the weld pull force, the better the welding effect and the better the battery stability.

[0085] Capacity retention was tested using a 5C charging rate. Specifically, at 25±3℃, a single cell was charged at a constant current of 0.5C to the highest cutoff voltage, rested for 30 minutes, and then discharged at a constant current of 0.5C to the lowest cutoff voltage; the discharged capacity was recorded as A1. Similarly, a single cell was charged at a constant current of 5C to the highest cutoff voltage, rested for 30 minutes, and then discharged at a constant current of 0.5C to the lowest cutoff voltage; the discharged capacity was recorded as A2. The 5C charging capacity retention rate was defined as A2 / A1. Ideally, it should be >90%, as a higher capacity retention rate indicates better battery performance.

[0086] The specific method for cycle life testing is to place a single cell at 25±3℃ for 30 minutes, then charge it to the highest cutoff voltage in 1C constant current charging mode, place it for 30 minutes, and then discharge it to the lowest cutoff voltage at 1C. Repeat the above steps to cycle until the number of cycles corresponding to a capacity retention rate of <80% is reached. The higher the number of cycles, the better the battery performance (the conventional simulated cycle life test method used in this application).

[0087] Table 2

[0088]

[0089] As shown in Table 2, the test results are better when the ratio of electrode assembly height to positive busbar thickness (h2:h1) is between 333 and 666:1. When the ratio of bare cell height to positive busbar thickness (h2:h1) is in other ranges, the overall test performance is poor.

[0090] Analysis revealed that excessive thickness of the positive busbar makes it difficult to weld through, affecting the welding performance and consequently reducing rate capability and cycle life. Conversely, insufficient thickness of the positive busbar affects its overall strength and overcurrent capability, leading to reduced welding tensile strength, charging rate capability, and cycle life.

[0091] In summary, by controlling the ratio of electrode assembly height to positive busbar thickness within h2:h1 = 333 to 666:1, the overall strength and current carrying capacity of the positive busbar can be guaranteed, while improving the welding pull-charge rate capability and cycle life.

[0092] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the scope of protection of this utility model.

Claims

1. A positive electrode busbar, characterized in that, include: The body part (42) has a first through hole (43) and a second through hole (44) penetrating the body part (42). The body part (42) is arc-shaped. The first through hole (43) is located at the center of the body part (42), and the second through hole (44) is arranged around the first through hole (43). The connecting part (41) is connected to one end of the main body part (42); Wherein, the total area of ​​the positive electrode busbar is S, the area of ​​the first through hole (43) is S1, and the total area of ​​the second through hole (44) is S2; 1 / 12≤(S1+S2) / S≤1 / 6.

2. The positive electrode busbar according to claim 1, characterized in that, 1 / 10≤(S1+S2) / S≤1 / 8.

3. The positive electrode busbar according to claim 1, characterized in that, The connecting part (41) is rectangular, and the connecting part (41) is connected to the chord of the body part (42) and extends outward in a radial direction.

4. The positive electrode busbar according to claim 1, characterized in that, The first through hole (43) is circular with a diameter of 5-6 mm.

5. The positive electrode busbar according to claim 1, characterized in that, The second through hole (44) is one or more of the following: triangle, square, rectangle, trapezoid, sector, circle, ellipse or irregular polygon; when the second through hole (44) is circular, the diameter of the second through hole (44) is 1 to 4 mm.

6. The positive electrode busbar according to claim 1, characterized in that, The number of the second through holes (44) is ≥2 and they are evenly distributed around the first through hole (43) in the circumferential direction.

7. A single-cell battery, characterized in that, include: The housing (7) includes a cylindrical receiving cavity with an opening; A cap assembly (2) is placed over the housing (7) to close the opening; Electrode assembly, the electrode assembly including bare cell (5) formed by winding a positive electrode, a separator and a negative electrode; And the positive electrode busbar (4) as described in any one of claims 1 to 6; the connecting part (41) is connected to the cap assembly (2); the body part (42) is connected to the electrode assembly.

8. The single-cell battery according to claim 7, characterized in that, The battery also includes a second insulating pad (3); the second insulating pad is provided with a third through hole, and the connecting part (41) passes through the third through hole and is connected to the cap assembly (2).

9. The single-cell battery according to claim 7, characterized in that, The thickness of the positive electrode busbar (4) is h1, and the height of the electrode assembly is h2, with h2:h1 being (333~666):

1.

10. The single-cell battery according to claim 7, characterized in that, The main body (42) is connected to the positive electrode tab of the electrode assembly by laser welding, and the connecting part (41) is connected to the cap assembly (2) by laser welding.

Images