Cathode collector plate and cylindrical lithium ion battery

Abstract

The utility model provides a cathode current collector plate and a cylindrical lithium ion battery, the cathode current collector plate comprises a plate body and a flange protruding along one side of the outer periphery of the plate body, the shape of the plate body is a closed pattern formed by alternately and sequentially connecting a plurality of arc edges and a plurality of concave edges end to end, the flange is arranged on the arc edges, and the concave edges are arranged on the flange. The inner concave edge is limited to form a notch in the outer periphery of the disc body, the disc body is provided with a center hole located in the center of the disc body and a plurality of auxiliary holes located in the periphery of the center hole, the perimeter of the disc body is H1, the total arc length of the turned-over edge is H2, and the range of H2 / H1 is 42%-58%. The flanging is only arranged at the edge of the arc edge, and the range of H2 / H1 is 42%-58%, so that the length of a welding wire can be effectively reduced when the cathode collector plate is welded with the shell, the risks of liquid leakage, pseudo soldering and solder skips at the welding position can be reduced, the internal resistance of the battery can be reduced, the weight of the cathode collector plate can be effectively reduced, and the service life of the battery is prolonged. And the energy density of the battery is improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a negative electrode current collector and a cylindrical lithium-ion battery. Background Technology

[0002] Currently, in 46-series cylindrical lithium-ion batteries, the negative electrode current collector typically includes a disc body and a flange around the perimeter of the disc body. During the assembly of the cylindrical lithium-ion battery, the disc body is welded to the negative terminal of the core, while the outer surface of the flange is bonded to the inner surface of the casing and connected by through-welding, thereby enabling the casing and the core to be electrically connected to the negative electrode. For example, in Chinese patent document CN221407360U, the disclosed cylindrical battery negative electrode current collector includes a welded perimeter 2 that substantially covers its outer circumference. This welded perimeter 2 is used to bond to the casing of the cylindrical battery and is connected by laser welding. However, the aforementioned flange increases the weight of the negative electrode current collector, thereby reducing the energy density of the battery. Furthermore, it leads to excessively long weld lines. Excessively long weld lines not only fail to reduce the battery resistance but also reduce the reliability of the weld, for example, increasing the risk of leakage, poor soldering, and incomplete soldering at the weld joint, which may increase the internal resistance of the battery.

[0003] Furthermore, during battery manufacturing, if a solution involving electrolyte injection on the negative electrode side is adopted, the aforementioned negative electrode current collector's flange is tightly fitted to the inner wall of the casing. The electrolyte can only enter the battery through the injection hole in the center of the negative electrode current collector, resulting in low injection efficiency and a high risk of overflow. Moreover, for cylindrical lithium-ion batteries using negative electrode-side pressure relief, if a short circuit or other thermal runaway occurs during use, a large amount of gas will be generated inside the casing. The current collector and flange will obstruct the gas from escaping from the negative electrode side, thereby increasing the battery's safety risks. Utility Model Content

[0004] This application provides a negative electrode current collector and a cylindrical lithium-ion battery to at least solve the technical problems of high internal resistance, poor welding reliability and low energy density of existing cylindrical lithium-ion batteries.

[0005] The first aspect of this application provides a negative electrode current collector, including a disk body and a flange protruding along one side of the outer periphery of the disk body. The disk body is a closed shape composed of multiple arc edges and multiple concave edges connected end to end in alternation. The flange is disposed on the arc edges, and the concave edges define a notch at the outer periphery of the disk body. The disk body has a central hole located at its center and multiple auxiliary holes located around the central hole. The perimeter of the disk body is H1, the total arc length of the flange is H2, and the range of H2 / H1 is 42% to 58%.

[0006] The negative current collector according to the embodiments of this application has at least the following beneficial effects:

[0007] First, by setting the flange only at the edge of the arc and setting the H2 / H1 range to 42% to 58%, the length of the weld line when welding it to the casing can be effectively reduced, thereby reducing the risk of leakage, poor welding, and missing welding at the welding point. This can reduce the internal resistance of the battery and also effectively reduce the weight of the negative electrode current collector, thereby improving the energy density of the battery.

[0008] Furthermore, by setting a notch at the break point of the flange, on the one hand, during the electrolyte injection process, the electrolyte will flow into the battery through the notch, improving the electrolyte injection efficiency, reducing the injection time, increasing production efficiency, and reducing the battery manufacturing cost. On the other hand, in the event of a short circuit or thermal runaway and a large amount of gas production inside the battery, some gas can be diverted through the notch, improving the venting efficiency and enhancing the battery safety.

[0009] In one possible implementation, the perimeter of the disc is H1, the total arc length of the notch is H3, and the ratio of H3 to H1 is in the range of 25% to 38%.

[0010] By setting the range of H3 / H1 appropriately, it is possible to ensure good welding effect between the disk body and the core while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0011] In one possible implementation, the concave edge is arc-shaped, and the maximum depth of the notch is H4, which ranges from 2 to 5 mm.

[0012] By reasonably setting the range of the maximum depth H4 of the notch, it is possible to ensure a good welding effect between the disk body and the core while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0013] In one possible implementation, the area of ​​the disc body is S1, the area of ​​the central hole is S3, and the range of S3 / S1 is 1% to 3%, wherein the area of ​​the disc body is the area of ​​the disc body when the central hole, the auxiliary hole, and the notch are not opened.

[0014] By setting the range of S3 / S1 appropriately, it is possible to ensure good welding effect between the disk body and the core while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0015] In one possible implementation, the total area of ​​the auxiliary holes is S4, and the ratio of S4 to S1 ranges from 9% to 21%.

[0016] By setting the S4 / S1 range appropriately, it is possible to ensure good welding between the disk body and the core while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0017] In one possible implementation, the total area of ​​the notch formed with reference to the outer periphery edge of the disc is S2, and the ratio of S2 / S1 ranges from 2% to 10%.

[0018] By setting the range of S2 / S1 appropriately, it is possible to ensure good welding effect between the disc and the core while taking into account the liquid injection efficiency and venting efficiency of the disc body. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0019] In one possible implementation, the radius of the disc is L1, the distance from the inner edge of the auxiliary hole to the center of the central hole is L2, and the ratio of L2 / L1 ranges from 18% to 36%.

[0020] By reasonably setting the range of L2 / L1, the structural strength of the connection between the central hole and the auxiliary hole can be taken into account, while ensuring the auxiliary injection effect of the auxiliary hole.

[0021] In one possible implementation, the auxiliary hole is an oblong hole, and the long axis of the auxiliary hole is aligned with the radial direction of the disk body.

[0022] By rationally designing the shape and arrangement of auxiliary holes, the opening area of ​​the auxiliary holes can be effectively increased without affecting the welding area, thereby improving the effect of auxiliary fluid injection.

[0023] In one possible implementation, the number of the arc edge, the concave edge, and the auxiliary hole are all four. The four arc edges and the four auxiliary holes are arranged in a one-to-one correspondence, and the midpoint of the arc edge, the center of the auxiliary hole, and the center of the central hole are collinear.

[0024] By rationally setting the number and arrangement of the arc edge, concave edge, and auxiliary holes, the structural strength of the disc can be effectively guaranteed while balancing and improving the venting efficiency and liquid injection efficiency, and the weldable area between the disc and the core can also be guaranteed.

[0025] A second aspect of this application provides a cylindrical lithium-ion battery, including a casing, a core, and a negative electrode current collector provided in the first aspect embodiment above. The disk body of the negative electrode current collector is connected to the negative end of the core, and the flange of the negative electrode current collector is connected to the shell wall of the casing by laser penetration welding.

[0026] The cylindrical lithium-ion battery according to the embodiments of this application has at least the following beneficial effects:

[0027] The cylindrical lithium-ion battery of this application embodiment has the characteristics of low internal resistance, high energy density and high welding reliability because it has the negative electrode current collector of the first aspect embodiment described above. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application 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.

[0029] Figure 1 This is a cross-sectional schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of this application;

[0030] Figure 2 This is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of this application;

[0031] Figure 3 yes Figure 2 A schematic diagram of the assembly of the negative current collector, the winding core, and the housing;

[0032] Figure 4 yes Figure 2 A front view of the negative current collector;

[0033] Figure 5 yes Figure 2 A schematic diagram of the area S1 of the negative current collector;

[0034] Figure 6 yes Figure 2 A schematic diagram of the area S2 of the negative current collector;

[0035] Figure 7 yes Figure 2 A schematic diagram of the area S3 of the negative current collector;

[0036] Figure 8 yes Figure 2 A schematic diagram of the area S4 of the negative current collector;

[0037] Figure 9 yes Figure 2 A front view of the negative current collector.

[0038] Figure label:

[0039] 100-Negative current collector, 110-Disc body, 111-Central hole, 112-Auxiliary hole, 113-Notch, 114-Circular edge, 115-Concave edge, 120-Flanged edge;

[0040] 200 - Core, 210 - Positive end, 220 - Negative end, 230 - Core hole;

[0041] 300 - Housing;

[0042] 400 - Positive electrode cover assembly; 410 - Terminal post;

[0043] 500 - Negative electrode cover plate, 510 - Sealing nail. Detailed Implementation

[0044] The embodiments of this implementation are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this implementation, and should not be construed as limiting this implementation.

[0045] In the description of this embodiment, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment.

[0046] In the description of this embodiment, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0047] In the description of this embodiment, unless otherwise explicitly limited, terms such as setting, installing, and connecting should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this embodiment in conjunction with the specific content of the technical solution.

[0048] Figure 1 This is a schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of this application. Figure 1 In a cylindrical lithium-ion battery, the negative electrode side is on top, and the positive electrode side is on the bottom. For example... Figure 1As shown, the cylindrical lithium-ion battery includes a negative electrode current collector 100, a core 200, a housing 300, a positive electrode cover assembly 400, and a negative electrode cover 500. The positive terminal 210 of the core 200 is connected to the positive electrode cover assembly 400, which has an external terminal post 410 serving as the positive electrode of the cylindrical lithium-ion battery. The negative terminal 220 of the core 200 is connected to the housing 300 via the negative electrode current collector 100. The housing 300 serves as the negative electrode of the cylindrical lithium-ion battery, used for electrical connection to external electrical equipment.

[0049] It is understood that the negative electrode cover 500 of the cylindrical lithium-ion battery is provided with an injection hole sealed by a sealing pin 510. Through this injection hole, electrolyte can be injected into the interior of the cylindrical lithium-ion battery from one side of the negative electrode cover. Simultaneously, structures such as explosion-proof grooves can be constructed on the negative electrode cover 500 to promptly open and release pressure in the event of an abnormal pressure increase inside the cylindrical lithium-ion battery. It is also understood that since the negative electrode current collector 100 is located inside the negative electrode cover 500, its construction significantly affects both electrolyte injection and pressure release on the negative electrode side. The negative electrode current collector 100 of this embodiment is described in detail below.

[0050] Figure 2 This is a schematic diagram of the structure of the negative electrode current collector 100 provided in the embodiments of this application. Figure 3 yes Figure 2 A schematic diagram of the combined structure of the intermediate negative electrode current collector 100, the winding core, and the housing, as shown below. Figure 2 Figure 3 As shown, the negative electrode current collector 100 includes a disk body 110 and a flange 120 protruding along one side of the outer periphery of the disk body 110. The disk body 110 is used to connect with the negative terminal 220 of the core 200, and the flange 120 is used to connect with the housing 300, so that a passage is formed between the core 200 and the housing 300, thereby the housing 100 itself serves as the negative electrode of the cylindrical lithium-ion battery.

[0051] It is understandable that the connection between the disc body 110 and the flange 120 can be any fixed connection method. To ensure the connection is stable, the structural strength is good, and the processing economy is good, the disc body 110 and the flange 120 can be connected as one piece, for example, by stamping.

[0052] like Figure 2 and Figure 3 As shown, the disk body 110 is the main structural part of the negative electrode current collector 100. It is generally a thin sheet, and has a through central hole 111 and multiple auxiliary holes 112. Furthermore, multiple notches 113 are formed at the outer periphery of the disk body 110. It can be understood that the disk body 110 has two opposing disk surfaces. Figure 2As shown, the flange 120 protrudes to one side from the edge of the disc body 110 at an angle approximately perpendicular to the disc surface, as... Figure 3 As shown, the disc surface on the side opposite to the protruding direction of the flange 120 can be used to weld to the negative terminal 220 of the core 200. In this case, the disc surface on the side where the flange 120 is located faces the opening direction of the housing 300. In the subsequent liquid injection process, the electrolyte will enter the battery through this side disc surface.

[0053] It is understandable that the cross-sectional shapes of the core 200 and the casing 300 of the cylindrical lithium-ion battery are both circular. Therefore, to facilitate welding between the disc 110 and the core 200, and to facilitate welding between the flange 120 and the casing 300, the outer contour shape of the negative electrode current collector 100 is generally circular. In this embodiment, due to the presence of the notch 113, the outer contour shape of the disc 110 is not a complete perfect circle. Figure 4 As can be seen, the shape of the disc body 110 is a closed shape composed of multiple alternating circular arc edges 114 and multiple concave edges 115 connected end to end.

[0054] As mentioned above, the disc 110 is not a complete circle, but the ends of each arc 114 that are arc-shaped can be extended to connect with each other to form a complete circle. Therefore, the disc 110 can be regarded as a circular component.

[0055] like Figure 2 and Figure 3 As shown, in this embodiment, the flange 120 is not a complete circular structure. Specifically, the flange 120 is only provided at the edge of the arc edge 114, that is, it appears that multiple notches 113 divide the flange 120 into multiple segments. In this way, each segment of the flange 120 fits well with the shell wall surface of the housing 300 and is connected by through welding. Meanwhile, at the break point of the flange 120, a notch 113 is provided. On the one hand, during the electrolyte injection process, when the electrolyte flows into the surface of the disc 110, some of the electrolyte will flow directly into the battery through the central hole 111 and the auxiliary hole 112, while some of the electrolyte will reach the outer periphery of the disc 110 along the surface of the disc 110. Due to the presence of the notch 113, this part of the electrolyte will flow into the battery through the notch 113, improving the electrolyte injection efficiency, reducing the injection time, increasing production efficiency, and reducing the battery manufacturing cost. On the other hand, in the event of a short circuit or thermal runaway and a large amount of gas production inside the battery, some of the gas can be diverted through the notch 113, improving the venting efficiency and enhancing the battery safety.

[0056] Understandably, by setting the flange 120 only at the edge 114 of the arc, the weight of the negative current collector 100 can be reduced to a certain extent, thereby increasing the energy density of the battery. In addition, since the flange 120 is not a complete circle, the length of the weld line when welding it to the casing 300 can be effectively reduced, thereby reducing the risk of leakage, poor welding, and incomplete welding at the welding point, and thus reducing the internal resistance of the battery.

[0057] It is also understandable that, for the negative electrode current collector 100, the art typically uses the method of opening pores inside the plate body 110 to improve the liquid injection efficiency. In the design process, it is also necessary to balance the weldable area of ​​the plate body 110 itself and construct a flange 120 on the edge of the plate body 110 to facilitate welding with the core 200 and the shell 300, and to design welding tooling fixtures. However, this application minimizes the adverse effects on the plate body 110 and the flange 120 by dividing the flange 120 into multiple segments and opening a notch 113 on the outer periphery of the plate body 110 for auxiliary liquid injection and venting. For example, by reasonably designing the size and shape of the notch 113, the influence on the welding of the plate body 110 can be effectively avoided.

[0058] Furthermore, from Figure 4 As can be seen, the notch 113 is a structure formed by indenting inward toward the center of the disc body 110 at the position where the flange 120 is not provided on the outer periphery. For example, the notch 113 can be formed at the outer periphery of the disc body 110 by removing material through various methods such as mechanical cutting and laser cutting.

[0059] Furthermore, it can be understood that notches 113 of various shapes can be formed on the outer periphery of the disc body 110, for example, Figure 4 The arc-shaped shape shown is such that, in this case, the notch 113 is defined by the concave edge 115 and the baseline of the outer periphery of the disk body 110. The baseline can be referenced... Figures 5 to 9 The dotted line at the notch 113 is for illustrative purposes. It represents the shape of the disk 110 before the notch 113 is cut out. The dotted line extends from the outer periphery of the disk 110 along the original direction of the outer periphery. Of course, it is not limited to this. For example, the notch 113 can be rectangular, fan-shaped, or waist-shaped.

[0060] It is understandable that at least one notch 113 needs to be provided to facilitate auxiliary venting and liquid injection at the outer periphery of the disc body 110. Of course, to further improve venting and liquid injection efficiency, multiple notches 113 can be provided. In this case, the arc edges 114 between multiple notches 113 will have multiple segments, and correspondingly, flanges 120 can be provided on these arc edges 114 respectively. However, this is not a limitation. Provided the requirements are met, the number of notches 113 and flanges 120 does not need to correspond one-to-one. For example, flanges 120 may not be provided on the arc edges 114 at certain locations.

[0061] like Figure 5 As shown, in some embodiments, there are four circular arc edges 114, four concave edges 115, and four auxiliary holes 112. The four circular arc edges 114 and the four auxiliary holes 112 are arranged in a one-to-one correspondence, and the midpoint of the corresponding circular arc edge 114, the center of the auxiliary hole 112, and the center of the central hole 111 are collinear. It can be understood that, in this way, the auxiliary holes 112 and the notch 113 are staggered along the radial direction of the disk body 110. By corresponding the number of the arc edge 114, the concave edge 115, and the auxiliary hole 112, and setting each to 4, it is beneficial to balance the liquid injection and venting effect of the disc body 110 and the welding effect between the flange 120 and the shell 300. At the same time, setting the central hole 111, the auxiliary hole 112, and the arc edge 114 to be collinear avoids the weakening of the structural strength of the disc body 110 caused by the collinearity of the auxiliary hole 112, the notch 113 and the central hole 111. This can effectively ensure the structural strength of the disc body 110, and at the same time ensure the weldable area between the disc body 110 and the core 200.

[0062] Furthermore, such as Figure 4 As shown, the auxiliary hole 112 is waist-shaped, meaning it is an oblong hole, and its major axis is aligned with the radial direction of the disk body 110. It is understandable that for large cylindrical batteries, the negative electrode current collector 100 also has a large surface area. By using an oblong shape for the auxiliary hole 112 and setting its major axis to extend along the radial direction of the disk body 110, the opening area of ​​the auxiliary hole 112 can be effectively increased without affecting the welding area, thereby improving the auxiliary liquid injection effect.

[0063] like Figure 5 and Figure 6 As shown, in some embodiments, the area of ​​the disc body 110 is S1, and the total area of ​​the notch 113 is S2. The ratio of S2 to S1 ranges from 2% to 10%, i.e., 2% ≤ S2 / S1 ≤ 10%. For example, S1 is 1604.6 mm. 2 S2 is 95.56mm. 2 The S2 / S1 ratio is 5.96%. Among them, such as... Figure 5As shown, the area S1 of the disk body 110 refers to the surface area of ​​the disk body 110, that is, the area of ​​the disk body 110 without the central hole 111, auxiliary hole 112, and notch 113, etc. Figure 6 As shown, the total area of ​​the notch 113, S2, is the sum of the areas of the closed shape defined by the concave edge 115 and the baseline (dashed line in the figure) of the outer periphery of the disk 110. Further, it can be understood that, for a single notch 113, its area refers to the area defined by the baseline of the outer periphery of the disk 110 and the boundary line of the notch 113 itself, i.e., the concave edge 115.

[0064] Understandably, if the total area S2 of the notch 113 is too small, on the one hand, the notch 113 will not significantly improve the electrolyte injection efficiency during the electrolyte injection process, and there will be a risk of electrolyte overflowing from the casing, causing problems such as electrolyte contamination, rusting, or even battery failure on the outer surface of the casing 300. Furthermore, additional manpower is needed to handle the overflow, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the notch 113, limiting its effectiveness in improving battery safety. Conversely, if the total area S2 of the notch 113 is too large, the notch 113 will occupy the welding area on the surface of the disk 110, reducing the actual effective welding area between the disk 110 and the negative terminal 220. The current-carrying capacity at the welding position will not meet the requirements, resulting in excessive overcurrent temperature rise and subsequent thermal control safety issues, thus reducing battery safety performance. Moreover, the reduced welding area will lead to an increase in the battery's internal resistance. By setting the range of S2 / S1 to 2% to 10%, it is possible to ensure good welding effect between the disc body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the disc body 110. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0065] As mentioned above, in this embodiment, a through central hole 111 is formed on the disk body 110. This central hole 111 is located at the center of the disk body 110 and is used to inject electrolyte into the battery. It should be noted that the center of the disk body 110 can be the center of a circle. (Combined with...) Figure 1 It is understandable that the core 200 is manufactured using a winding process, and after winding, a circular core hole 230 is formed at the center of the core 200. To match the shape of the core hole 230, the shape of the center hole 111 is preferably circular. In this case, the center hole 111 and the disc body 110 are concentric. It is also understandable that the diameter of the center hole 111 can be specifically selected based on the balance between achieving liquid injection efficiency and weldable area.

[0066] Furthermore, such as Figure 5 and Figure 7As shown, in some embodiments, the area of ​​the central hole 111 is S3, and the ratio of S3 to S1 ranges from 1% to 3%, i.e., 1% ≤ S3 / S1 ≤ 3%. For example, the area of ​​the central hole 111 is 28.27 mm². 2 S1 is 1604.6mm 2 S4 / S1 is 1.76%. Among them, the central hole 111 is located at the center of the disk body 110, and there is only one of them. Therefore, the area S3 of the central hole 111 here refers only to the area of ​​the central hole 111 itself.

[0067] Understandably, if the area S3 of the central hole 111 is too small, on the one hand, during the electrolyte injection process, the narrow injection channel makes it difficult for the electrolyte to be injected into the battery, increasing the injection time and reducing injection efficiency; on the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the central hole 111, reducing battery safety. Conversely, if the area S3 of the central hole 111 is too large, the central hole 111 will occupy the welding area on the disk surface of the disk 110, reducing the actual effective welding area between the disk 110 and the negative terminal 220. The current-carrying capacity at the welding position will not meet the requirements, resulting in excessive overcurrent temperature rise and subsequent thermal control and other safety issues, thus reducing battery safety performance. Furthermore, the reduced welding area will lead to an increase in the battery's internal resistance. By setting the range of S3 / S1 to 1% to 3%, it is possible to ensure good welding effect between the disk body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector 100. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0068] As mentioned above, in this embodiment, a through auxiliary hole 112 is provided on the disc body 110. The auxiliary hole 112 is located around the central hole 111 and is used to assist in electrolyte injection. It can be understood that the size of the auxiliary hole 112 can be specifically selected according to the balance between achieving electrolyte injection efficiency and weldable area.

[0069] Furthermore, such as Figure 5 and Figure 8 As shown, in some embodiments, the total area of ​​the auxiliary hole 112 is S4, and the ratio of S4 to S1 ranges from 9% to 21%, i.e., 9% ≤ S4 / S1 ≤ 21%. For example, the total area of ​​the auxiliary hole 112 is 226.27 mm. 2 S1 is 1604.6mm 2 S4 / S1 is 14.1%. Among them, the total area S4 of the auxiliary holes 112 refers to the sum of the areas of all the auxiliary holes 112 on the disk body 110.

[0070] Understandably, if the total area S4 of the auxiliary hole 112 is too small, on the one hand, the increased injection time during the electrolyte injection process will lead to a decrease in injection efficiency and a risk of electrolyte overflow, resulting in problems such as electrolyte contamination, rusting, and even battery failure on the outer surface of the casing. Furthermore, additional manpower is required to handle the overflow, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the auxiliary hole 112, limiting its effectiveness in improving battery safety. Conversely, if the total area S4 of the auxiliary hole 112 is too large, the auxiliary hole 112 will occupy the welding area on the surface of the disk 110, reducing the welding area between the disk 110 and the negative terminal 220. The current-carrying capacity at the welding position will not meet the requirements, resulting in excessive overcurrent temperature rise and subsequent thermal control safety issues, thus reducing battery safety performance. Furthermore, the reduced welding area will increase the battery's internal resistance. By setting the range of S4 / S1 from 9% to 21%, it is possible to ensure good welding between the disc body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector 100. In addition, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0071] As mentioned earlier, the disc body 110 is a closed shape composed of multiple alternating arc edges 114 and multiple concave edges 115 connected end to end. Thus, the outer periphery of the disc body 110 includes multiple arc edges 114 that are disconnected from each other. As mentioned earlier, the two ends of each arc edge 114 can be extended to connect and form a complete circle. Therefore, the disc body 110 can be considered a circular component. It can be understood that these arc edges 114 themselves are partial arc segments of a complete circle, and multiple flanges 120 are correspondingly arranged on these arc edges 114, with each flange 120 extending along the edge of the arc edge 114, thus each flange 120 is also arc-shaped. It should be noted that the arc length of the flange 120 can be less than the arc length of the arc edge 114. In this case, the notch 113 and the flange 120 are not directly connected.

[0072] In some embodiments, such as Figure 9 As shown, let H1 be the perimeter of the disc body 110 and H2 be the total arc length of the flange 120. The ratio of H2 / H1 ranges from 42% to 58%, i.e., 42% ≤ H2 / H1 ≤ 58%. For example, if the perimeter H1 of the disc body 110 is 142 mm and the total arc length H2 of the flange 120 is 70.68 mm, then H2 / H1 is 49.77%. Here, the perimeter H1 of the disc body 110 refers to the perimeter of the complete circular shape along the edge 114, i.e. Figure 5 The perimeter of the outer contour of the shaded area, while the total arc length of flange 120, H2, refers to the sum of the arc lengths of multiple flange segments 120. Figure 9(Only the arc length of one flange 120 is marked in the text). For example, if the disc body 110 has a total of 4 flanges 120, and the arc length of each flange is 17.67mm, then the total arc length H2 of the flanges 120 is 70.68mm.

[0073] Understandably, when welding the flange 120 to the housing 300, the clamping fixture occupies part of the flange 120. If the total arc length H2 of the flange 120 is too small, it will be difficult to position it, and it will also affect the actual welding area, reducing the effective welding area. This will lead to a decrease in the current carrying capacity at the weld, resulting in excessive temperature rise during subsequent use, and will also increase internal resistance, thus affecting battery performance. Conversely, if the total arc length H2 of the flange 120 is too large, it will increase the weight of the negative electrode current collector 100, thereby reducing the energy density of the battery. It will also lead to excessively long welding wires. Excessively long welding wires will not only fail to reduce the battery resistance, but will also reduce the reliability of the welding. For example, it will increase the risk of leakage, poor welding, and incomplete welding at the weld, which may increase the internal resistance of the battery. By setting the H2 / H1 range to 42%–58%, it is possible to achieve a good welding effect between the flange 120 and the housing 300 while ensuring that the negative electrode current collector 100 is relatively light, thereby improving the energy density of the battery and effectively avoiding increasing the internal resistance of the battery.

[0074] In some embodiments, such as Figure 9 As shown, let H1 be the circumference of the disc 110 and H3 be the total arc length of the notch 113. The ratio of H3 / H1 is between 25% and 38%, i.e., 25% ≤ H3 / H1 ≤ 38%. For example, if the circumference of the disc 110 is H1 = 142 mm and the total arc length of the notch 113 is H3 = 45.32 mm, then H3 / H1 is 31.92%. Here, the circumference of the disc 110, H1, refers to the circumference of the complete circular shape along the edge 114 of the arc. Figure 5 The perimeter of the outer contour of the shaded area, while the total arc length H3 of the notch 113 refers to the arc length after deducting the total arc length along the edge 114 from the perimeter of the aforementioned disk body 110, that is... Figure 9 The sum of the arc lengths of the dashed sections in the middle ( Figure 9 (Only the arc length of a dashed line is marked in the text). For example, the disk body 110 has a total of 4 notches 113. The arc length of each individual notch 113 is 11.33mm, so the total arc length H3 of the notches 113 is 45.32mm.

[0075] Understandably, if the total arc length H3 of the notch 113 is too short, on the one hand, the increased injection time during the electrolyte injection process will lead to a decrease in injection efficiency and a risk of electrolyte overflow, causing problems such as electrolyte contamination of the casing, rusting, and even battery failure. Furthermore, increased manpower is required to handle the overflow, increasing manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the notch 113, limiting its effectiveness in improving battery safety. Conversely, if the total arc length H3 of the notch 113 is too long, the notch 113 will occupy the welding area on the surface of the disk 110, reducing the actual effective welding area between the disk 110 and the negative terminal 220. The current-carrying capacity at the welding position will not meet the requirements, resulting in excessive overcurrent temperature rise and subsequent thermal control safety issues, thus reducing battery safety performance. Furthermore, the reduced welding area will increase the battery's internal resistance. By setting the H3 / H1 range to 25%–38%, it is possible to ensure good welding between the disc body 110 and the core 200 while taking into account the liquid injection efficiency and venting efficiency of the negative electrode current collector 100. Furthermore, it is also possible to effectively avoid increasing the internal resistance of the battery.

[0076] In some embodiments, such as Figure 9 As shown, the maximum depth H4 of the notch 113 ranges from 2 to 5 mm, i.e., 2 mm ≤ H4 ≤ 5 mm. It should be noted that the maximum depth H4 of the notch 113 refers to the distance from the highest point of the baseline at the outer perimeter of the disc 110 to the deepest point of the notch 113. For example, Figure 9 The concave edge 115 shown is arc-shaped, and its deepest point is located at the midpoint of the arc-shaped concave edge 115. The highest point of the baseline of the outer periphery of the disc 110 is located at the midpoint of the dashed line. Therefore, in this case, the maximum depth H4 is the distance between the midpoint of the concave edge 115 and the midpoint of the dashed line.

[0077] Understandably, if the maximum depth H4 of the notch 113 is too small, meaning the notch 113 is too shallow, the area of ​​the notch 113 will be smaller, and the channel formed between the notch 113 and the casing 300 will be narrow. On the one hand, during the electrolyte injection process, the notch 113 will not significantly improve the electrolyte injection efficiency, and there will be a risk of electrolyte overflow, which could cause problems such as electrolyte contamination, rusting, or even battery failure on the outer surface of the casing. In addition, more manpower is needed to handle the overflow problem, which would increase manufacturing costs. On the other hand, if a short circuit or other thermal runaway occurs during battery use, the gas generated inside the battery cannot be discharged in time through the notch 113, thus having a limited effect on improving battery safety. Conversely, if the maximum depth H4 of the notch 113 is too large, i.e., the notch 113 is too deep, the notch 113 will occupy the welding area on the surface of the disc 110, resulting in a reduction in the actual effective welding area between the disc 110 and the negative terminal 220. The current-carrying capacity at the welding position will not meet the requirements, leading to excessive overcurrent temperature rise and subsequent safety issues such as thermal control, thus reducing the battery's safety performance. Furthermore, the reduced welding area will increase the battery's internal resistance. By setting the maximum depth H4 of the notch 113 within the range of 2–5 mm, it is possible to ensure a good welding effect between the disc 110 and the core 200 while balancing the liquid injection efficiency and venting efficiency of the disc 110, and also effectively avoid increasing the battery's internal resistance.

[0078] like Figure 9 As shown, in some embodiments, the central hole 111 and the arc edge 114 are co-centered. With the radius of the disk body 110 as L1, the distance from the inner edge of the auxiliary hole 112 to the center of the central hole 111 is L2. The ratio of L2 / L1 ranges from 18% to 36%, i.e., 18% ≤ L2 / L1 ≤ 36%. For example, L1 is 22.6 mm, L2 is 6 mm, and L2 / L1 is 26.55%.

[0079] It is understandable that the dimensions of a cylindrical lithium-ion battery are basically fixed, that is, the diameter of the cylindrical lithium-ion battery casing is determined. Therefore, the diameter of the disk 110 of the negative electrode current collector 100 assembled into the casing is basically determined. Since the central hole 111 is located at the center of the disk 110, if L2 / L1 is too small, the auxiliary hole 112 will be too close to the central hole 111. In this case, the structural strength of the connection between the auxiliary hole 112 and the central hole 111 may be insufficient, and there is a risk of breakage. Moreover, once this part breaks, metal shavings will be generated, and the burrs generated at the fracture point can easily deform inward and puncture the separator. Both metal shavings and burrs may cause short circuit failure of the battery, which poses a safety risk. Conversely, if L2 / L1 is too large, the auxiliary hole 112 will be too far from the central hole 111. During the electrolyte injection process through the central hole 111, if the central hole 111 cannot meet the injection speed requirements, the time it takes for the electrolyte to spread from the surface of the disk 110 to the auxiliary hole 112 will increase. Furthermore, during this spread, the electrolyte will continuously inject into the battery, easily causing overflow. This can lead to problems such as electrolyte contamination of the outer surface of the casing, rusting, and even battery failure. Additionally, it requires additional manpower to handle the overflow, increasing manufacturing costs. By setting L2 / L1 within the range of 18% to 36%, the structural strength of the connection between the central hole 111 and the auxiliary hole 112 can be ensured while maintaining the effective auxiliary injection of the auxiliary hole 112.

[0080] The effects of this application will be further described below with specific embodiments and comparative examples.

[0081] It should be noted that the following embodiments and comparative examples of this application are all based on the design and fabrication of the 4680 cylindrical lithium-ion battery commonly used in the art. Therefore, except for fabricating the negative electrode current collector 100 according to the aforementioned structure, other components and materials can be obtained with reference to the 4680 cylindrical lithium-ion battery. For example, the positive electrode sheet, negative electrode sheet, and electrolyte can be obtained by referring to the following preparation method:

[0082] To prepare the positive electrode sheet: take lithium nickel cobalt manganese oxide, carbon nanotube conductive agent, conductive carbon black, and polyvinylidene fluoride (PVDF) binder as the solid materials of the positive electrode slurry, disperse the solid materials in N-methyl-2-pyrrolidone, mix them evenly in a homogenizer, coat the slurry on both sides of aluminum foil, and dry it to obtain the positive electrode sheet.

[0083] To prepare the negative electrode sheet: Take the negative electrode active material, acetylene black conductive agent, thickener (hydroxymethyl cellulose), and polyacrylate binder as the solid substances of the negative electrode slurry. Disperse the solid substances in deionized water, mix them evenly in a homogenizer, coat the slurry on both sides of the copper foil, and dry it to obtain the negative electrode sheet.

[0084] Preparation of electrolyte: Ethylene carbonate, methyl ethyl carbonate and diethyl carbonate are mixed to obtain an organic solvent. Then, the thoroughly dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare the electrolyte.

[0085] The components and materials obtained in the aforementioned manner can be assembled according to known techniques in the art to obtain an experimental cylindrical lithium-ion battery. For example, after the positive electrode sheet and negative electrode sheet are rolled, slit, and die-cut, they are wound together with the separator. The positive electrode sheet, negative electrode sheet, and separator are wound together by a winding machine to form a core 200. The two ends of the core 200 are cut and stacked to form positive electrode tabs and negative electrode tabs. Then, the negative electrode current collector 100 and the positive electrode current collector are welded to the core 200, respectively. The negative electrode current collector 100 is then welded to the casing 300. The negative electrode cover plate 500 is then welded to the casing 300. After liquid injection, sealing, and formation processes are completed, an experimental cylindrical lithium-ion battery is obtained.

[0086] Example 1:

[0087] Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100. The negative electrode current collector 100 includes a disk body 110 and four flanges 120 protruding from the outer periphery of the disk body 110. One side of the disk body 110 of the negative electrode current collector 100 is laser-welded to a core 200, and the flanges 120 are attached to the shell wall of the housing 300 in a direction away from the core 200, and the two are connected by laser through welding. The disk body 110 has a central hole 111 located at its center and four auxiliary holes 112 located around the central hole 111. Four arc-shaped notches 113 are also provided on the outer periphery of the disk body 110. The midpoint of each arc edge 114, the center of the auxiliary holes 112, and the center of the central hole 111 are collinear. Furthermore, the negative electrode current collector 100 also satisfies the following parameters:

[0088] The perimeter of the disk 110 is H1, which is 142 mm; the total arc length of the flange 120 is H2, which is 70.68 mm; the total arc length of the notch 113 is H3, which is 45.32 mm; and the depth of the notch 113 is H4, which is 3 mm. From the above, it can be seen that in the negative electrode current collector 100, H2 / H1 = 50% and H3 / H1 = 32%.

[0089] Comparative Example 1:

[0090] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that: H2 / H1 = 35%.

[0091] Comparative Example 2:

[0092] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that: H2 / H1 = 68%.

[0093] Comparative Example 3:

[0094] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that H3 / H1 = 20%.

[0095] Comparative Example 4:

[0096] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that H3 / H1 = 45%.

[0097] Comparative Example 5:

[0098] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that H4 = 1.25 mm.

[0099] Comparative Example 6:

[0100] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector 100, and differs from Example 1 in that H4 = 6.5 mm.

[0101] Table 1 below evaluates the electrolyte injection time (t), the maximum temperature of the negative electrode current collector and the core solder joint (Tmax), and the battery internal resistance (R) of the negative electrode current collector 100 fabricated in the above embodiments and comparative examples. Wherein:

[0102] The specific test method for electrolyte injection time (t) is as follows: The negative electrode current collector 100 prepared in the above embodiment and comparative example is installed inside the battery. Following the normal cell manufacturing process, after the grooving process, the electrolyte injection stage is reached. 75g of electrolyte is injected into the holding cup, and the holding cup is pressed into the groove opening of the grooving. The sealing ring below the holding cup is completely attached to the groove depth end face. Then, the electrolyte is injected. First, a negative pressure is drawn to -90KPa in the holding cup. The decrease in electrolyte height can be observed from the holding cup. Electrolyte flows into the battery and is maintained for 40 seconds before switching to positive pressure injection. Nitrogen gas is then introduced into the battery to gradually increase the internal pressure to 0.8 MPa. Electrolyte continues to flow into the battery from the holding cup, and the electrolyte level in the holding cup gradually decreases. Then, the pressure is adjusted to negative pressure injection, and this cycle of positive and negative pressure injection is repeated until all the electrolyte in the holding cup has flowed into the battery. The time taken for the electrolyte level in the holding cup to drop to 0 is recorded (in seconds).

[0103] The specific test method for the maximum temperature (Tmax) of the negative electrode current collector and the core solder joint is as follows: The negative electrode current collector 100 prepared in the above embodiment and comparative example is assembled into an experimental cylindrical lithium-ion battery. A through hole with a diameter of 3mm is drilled on the negative electrode cover plate 500 of the experimental cylindrical lithium-ion battery. The temperature control wire is passed through the through hole and attached to the solder joint of the negative electrode current collector 100 and the core 200. After liquid injection according to the normal sample preparation process, the negative electrode cover plate 500 is sealed and subjected to capacity testing to produce a qualified cylindrical lithium-ion battery. It is charged and discharged for 10 cycles at a 3C high rate. After 10 cycles of charge and discharge, the temperature data of the welding area collected by the temperature control wire is obtained. The maximum value Tmax (unit: degrees Celsius) within the temperature fluctuation range within 10 cycles is taken and recorded.

[0104] The specific test method for the battery internal resistance (R) is as follows: The negative electrode current collector 100 and the core 200 prepared in the above embodiment and comparative example are welded together and placed in the shell 300. Welding is carried out according to the normal process. All batteries adopt a ternary high-nickel system, and the ratio, electrolyte, positive and negative electrode formula and material selection are kept consistent. The flange 120 of the negative electrode current collector 100 is welded to the shell wall of the shell 300 through the welding. The welding parameters are: welding focal length is 0, welding speed is 160mm / s, welding power is 330W. After welding a weld mark with a width of 0.6mm along the arc length of the flange 120, it is transferred to the subsequent liquid injection and sealing, and then subjected to formation and capacity testing. After being made into a qualified cylindrical lithium-ion battery, its internal resistance (unit: mΩ) is tested.

[0105] Table 1

[0106]

[0107]

[0108] Table 1 shows that when the H2 / H1 ratio is set to 42%–58%, the H3 / H1 ratio to 25%–38%, and the H4 ratio to 2–5 mm, the electrolyte injection time (t) is 705 seconds, and the battery internal resistance (R) is 2.7 mΩ, it can be seen that within the above numerical ranges, the electrolyte injection rate and welding internal resistance of the negative electrode current collector can be well balanced, thereby effectively improving the battery's safety and charge / discharge performance, as well as reducing the battery's production cost.

[0109] As shown in Table 1, both excessively large and small H2 / H1 ratios will increase the battery's internal resistance and the maximum temperature at the welding point between the negative current collector 100 and the winding core 200 to some extent. Therefore, setting H2 / H1 within a reasonable range can balance the welding temperature rise of the negative current collector 100 and the battery's internal resistance.

[0110] As shown in Table 1, if the maximum depth H4 of the notch 113 remains unchanged, and H3 / H1 is too large, the opening area of ​​the notch 113 will increase. This will increase the liquid injection rate, but the temperature rise at the welding point between the disc 110 and the core 200 will increase to some extent, and the internal resistance of the battery will also increase. Conversely, if H3 / H1 is too small, the opening area of ​​the notch 113 will decrease. This will ensure that the temperature rise at the welding point between the disc 110 and the core 200 and the internal resistance of the battery are within a reasonable range, but it will reduce the liquid injection rate to some extent.

[0111] As shown in Table 1, if H4 is too large when the arc length of notch 113 remains constant, the opening area of ​​notch 113 will increase. This will increase the liquid injection rate, but the temperature rise at the welding point between the disc 110 and the core 200 will increase to some extent, and the internal resistance of the battery will also increase. Conversely, if H4 is too small, the opening area of ​​notch 113 will decrease. This will ensure that the temperature rise at the welding point between the disc 110 and the core 200 and the internal resistance of the battery are within a reasonable range, but the liquid injection rate will decrease to some extent.

[0112] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this implementation. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0113] Although embodiments of this implementation have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this implementation, the scope of which is defined by the claims and their equivalents.

Claims

1. A negative current collector plate characterized by, The disc body (110) is shaped as a closed figure composed of a plurality of circular arc edges (114) and a plurality of concave edges (115) connected in sequence, the flange (120) is arranged on the circular arc edge (114), the concave edge (115) defines a notch (113) at the outer periphery of the disc body (110), the disc body (110) is provided with a central hole (111) at the center and a plurality of auxiliary holes (112) at the outer periphery of the central hole (111), the circumference of the disc body (110) is H1, the total arc length of the flange (120) is H2, and the range of H2 / H1 is 42%-58%.

2. The negative current collector plate of claim 1, wherein The circumference of the disc body (110) is H1, the total arc length of the notch (113) is H3, and the range of H3 / H1 is 25%-38%.

3. The negative current collector plate of claim 1, wherein The concave edge (115) is arc-shaped, the maximum depth of the notch (113) is H4, and the range of H4 is 2-5mm.

4. The negative current collector plate according to any one of claims 1 to 3, characterized in that, The area of the disc body (110) is S1, the area of the central hole (111) is S3, and the range of S3 / S1 is 1%-3%, wherein the area of the disc body (110) is the area of the disc body (110) without the central hole (111), the auxiliary hole (112) and the notch (113).

5. The negative current collector plate of claim 4, wherein The total area of the auxiliary hole (112) is S4, and the range of S4 / S1 is 9%-21%.

6. The negative current collector plate of claim 5, wherein The total area of the notch (113) formed with the outer periphery edge of the disc body (110) as a reference is S2, and the range of S2 / S1 is 2%-10%.

7. The negative current collector plate according to any one of claims 1 to 3, characterized in that, The radius of the disc body (110) is L1, the distance from the inner side edge of the auxiliary hole (112) to the center of the central hole (111) is L2, and the range of L2 / L1 is 18%-36%.

8. The negative current collector plate of claim 7, wherein, The auxiliary hole (112) is a waist-shaped hole, and the long axis direction of the auxiliary hole (112) is consistent with the radial direction of the disc body (110).

9. The negative current collector plate of any one of claims 1 to 3, wherein, The number of the circular arc edge (114), the concave edge (115) and the auxiliary hole (112) is 4, the four circular arc edges (114) and the four auxiliary holes (112) are arranged one by one, and the midpoint of the corresponding circular arc edge (114), the center of the auxiliary hole (112) and the center of the central hole (111) are collinear.

10. A cylindrical lithium-ion battery, characterized by, The negative electrode current collecting disc (100) of any one of claims 1-9, the roll core (200) and the shell (300) are provided, the roll core (200) is arranged in the shell (300), the disc body (110) of the negative electrode current collecting disc (100) is connected with the negative electrode end (220) of the roll core (200), and the flange (120) of the negative electrode current collecting disc (100) is connected with the shell wall of the shell (300) through laser penetration welding.

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