A positive current collector and cylindrical lithium battery

Abstract

The utility model provides a kind of positive electrode current collector disc and cylindrical lithium battery, it is related to battery field.The positive electrode current collector disc includes disc body and tail body, disc body is the disc with arc-shaped gap, tail body is strip structure;Disc body is connected with tail body through its arc-shaped gap position;Along symmetry axis direction, positive electrode current collector disc is equipped with first bending line and second bending line, first bending line is located in the arc-shaped gap position of disc body, the highest point of disc body to the part of first bending line is first section;Second bending line divides tail body into second section and third section;Second section and third section are transitioned by chamfer, and the width of third section is greater than the width of second section.The positive electrode current collector disc of the utility model overcomes the problem that original groove is easy to bend, and increases the area of tail body and cap welding end, reduces the risk of disc body and tail body tearing, with higher safety performance, production efficiency and yield.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and more specifically, to a positive electrode current collector and a cylindrical lithium battery. Background Technology

[0002] Lithium-ion batteries have stood out among chemical energy storage devices due to their advantages such as high energy density, no memory effect, long cycle life, and environmental friendliness, and have attracted widespread attention from industries such as electric vehicles and 3C products.

[0003] The current collector structure is an important component of a battery, used to connect with the terminals and the tabs of the cell to enable charging and discharging. To achieve high-rate charging and discharging of cylindrical lithium batteries, sodium batteries, or lithium manganese iron phosphate batteries, the wound cell is designed with a full tab structure. After the full tab structure cell is flattened, the positive and negative current collectors are welded to the end face of the flattened cell using laser welding. Before welding the positive current collector to the cap, the positive current collector needs to be bent at 90°. At the connection between the positive current collector and the cap, the current collector needs to be bent in a "Z" shape before the cap is fastened.

[0004] To promptly sever the connection between the disc and the cap in the event of an internal short circuit, a groove (narrowing area) is typically provided on the long side of the tail section. The width of the groove is smaller than other parts to increase the resistance at this point, allowing the tail section to melt quickly at the groove during a short circuit, thus providing a safety function. However, this structure is prone to bending at the groove during the first bend, and after a second reverse bend, the tail section may protrude from the disc, affecting the subsequent insertion of the disc into the casing.

[0005] In view of this, this utility model is proposed. Utility Model Content

[0006] The purpose of this invention is to provide a positive electrode current collector and a cylindrical lithium battery to solve the problems mentioned in the background art.

[0007] The embodiments of this utility model can be implemented as follows:

[0008] On the one hand, this utility model provides a positive electrode current collector for a cylindrical lithium battery, which includes a disk body and a tail body. The disk body is a disc shape with an arc-shaped notch, and the tail body is a strip-shaped structure. The disk body is connected to the tail body through the position of its arc-shaped notch.

[0009] Along the axis of symmetry, the positive electrode current collector has a first bend line and a second bend line. The first bend line is located at the arc-shaped notch of the plate body, and the part from the highest point of the plate body to the first bend line is the first segment. The second bend line divides the tail body into the second segment and the third segment. The second segment and the third segment are connected by a chamfer, and the width of the third segment is greater than the width of the second segment. The length ratio of the first segment, the second segment and the third segment is (1.5~1.7):(1.05~1.15):1.

[0010] In some implementations, the chamfer angle between the second and third segments is 30°-45°; and / or, the width ratio of the second and third segments is 1:(1.8~2.2).

[0011] In some embodiments, the two corners of the third segment away from the second segment are provided with rounded chamfers, the radius of which is 0.45~0.55 mm.

[0012] In some embodiments, a circular central hole is provided at the center of the disk body, and at least one circular peripheral hole is provided around the central hole;

[0013] The centers of the outer holes are all located on a ring concentric with the central hole. The ratio of the diameter of the outer hole to the diameter of the central hole is 0.5-0.7. The ratio of the diameter of the central hole to the diameter of the ring and the disc is 1:(2~2.1):(3.06~4.14).

[0014] In some implementations, the ratio of the width of the second segment to the diameter of the central hole is (1.15-1.25):1.

[0015] In some embodiments, the ratio of the minimum distance from the center hole to any peripheral hole to the minimum distance from any peripheral hole to the edge of the disk body is 1:(0.9~1.1).

[0016] In some embodiments, the arc notch of the disc body is connected to the tail body by an arc segment with a central angle of 50°-75°.

[0017] In some embodiments, the ratio of the distance from the first bend line to the center of the disk to the radius of the disk is 1:(1.4~1.6).

[0018] In some implementations, the thickness of the positive current collector is 0.2 ± 0.03 mm.

[0019] On the other hand, this utility model provides a cylindrical lithium battery, which includes the above-mentioned positive electrode current collector.

[0020] The beneficial effects of the battery casing and battery provided in this embodiment of the utility model include:

[0021] This invention improves the groove structure of the tail section of the existing positive current collector and optimizes the structure of the connection between the plate and the tail, as well as the peripheral and central holes on the plate. This makes the obtained positive current collector overcome the problem of easy bending of the original groove, and increases the area of ​​the welding end between the tail and the cap, reducing the risk of tearing between the plate and the tail. It has higher safety performance, production efficiency and yield. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the positive electrode current collector provided in this embodiment;

[0024] Figure 2 This is another structural schematic diagram of the positive electrode current collector provided in this embodiment;

[0025] Figure 3 This is a side view of the positive current collector provided in this embodiment.

[0026] Icons: 1-Disc body; 2-Tail body; 3-Center hole; 4-Outer hole; H1-First segment; H2-Second segment; H3-Third segment; L1-Minimum distance from the center hole to any outer hole; L2-Minimum distance from the outer hole to the edge of the disc body; R1-Diameter of the outer hole; R2-Diameter of the center hole; R3-Diameter of the disc body; R4-Diameter of the ring. Detailed Implementation

[0027] During the assembly of cylindrical lithium batteries, before welding the positive current collector to the cap, the positive current collector needs to be bent at a 90-degree angle. At the connection between the positive current collector and the cap, the current collector needs to be bent in a "Z" shape before the cap is fastened. However, because the existing positive current collector has a groove on the long side of the tail body 2, this groove is prone to bending during the first bending of the positive current collector, and after the second reverse bending, the tail body 2 may protrude from the plate body 1, affecting the subsequent insertion of the plate body 1 into the casing.

[0028] To address the aforementioned issues, this utility model provides a positive current collector, which improves the groove structure of the tail body 2 and optimizes the structure of the connection between the plate body 1 and the tail body 2, thereby improving assembly quality and effectiveness.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] In the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed during use, they are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model.

[0033] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0034] It should be noted that, where there is no conflict, the features in the embodiments of this utility model can be combined with each other.

[0035] The following describes in detail the overall structure, working principle, and technical effects of the battery casing provided by this utility model through embodiments and in conjunction with the accompanying drawings.

[0036] Please refer to Figure 1 The positive electrode current collector provided by this utility model is applied in cylindrical lithium batteries.

[0037] The structure of the positive electrode of a cylindrical lithium battery is as follows: the positive electrode tab in the core is welded to one end of the Z-shaped positive electrode current collector, and the other end of the positive electrode current collector is welded or pressed to the inside of the battery cap, so that a passage is formed between the core and the cap through the positive electrode current collector.

[0038] The positive current collector of this utility model includes a disk body 1 and a tail body 2 connected to each other. The disk body 1 is used to connect with the core, and the tail body 2 is used to connect with the cap. Specifically, the disk body 1 is a disc shape with an arc-shaped notch, and the tail body 2 is a strip structure; the disk body 1 is connected to the tail body 2 through the arc-shaped notch.

[0039] like Figure 2 As shown, along the axis of symmetry, the positive electrode current collector has a first bend line and a second bend line. The first bend line is located at the arc-shaped notch of the disk body 1. The part from the highest point of the disk body 1 to the first bend line is the first segment H1. The second bend line divides the tail body 2 into the second segment H2 and the third segment H3. The second segment H2 and the third segment H3 are connected by a chamfer transition, and the width of the third segment H3 is greater than the width of the second segment H2.

[0040] In some embodiments, the length ratio of the first segment H1, the second segment H2, and the third segment H3 is (1.5~1.7):(1.05~1.15):1. This arrangement ensures that within the limited space of the battery casing, the winding core is as large as possible along the height of the casing, while the positive electrode current collector is bent into a "Z" shape.

[0041] In some embodiments, the chamfer angle between the second segment H2 and the third segment H3 is 30°-45°; more preferably, the chamfer angle between the second segment H2 and the third segment H3 is 35°-40°; the width ratio of the second segment H2 to the third segment H3 is 1:(1.8~2.2). This invention improves the tail body 2 with the grooved structure to a tail body 2 composed of two strip-shaped structures with a chamfered transition. This not only solves the assembly problems caused by the groove but also increases the welding area between the tail body 2 and the cap.

[0042] In some embodiments, the two corners of the third segment H3 away from the second segment H2 (i.e., the bottom of the tail body 2) are provided with rounded chamfers, the radius of which is 0.45~0.55 mm. By designing the bottom of the tail body 2 with rounded chamfers, the problem of the tail body 2 possibly protruding from the disc body 1 after a second reverse bend can be avoided. At the same time, sharp right-angled edges may scratch other components, but rounded chamfers provide smooth guidance and can reduce the risk of damage during assembly.

[0043] In some embodiments, the arc-shaped notch of the disc body 1 is connected to the tail body 2 by several tangent arc segments. Specifically, the highest point of the arc-shaped notch is located outside the ring containing the center of the outer hole 4, and it is connected to the tail body 2 by arc segments. The radius of the rounded corner at the connection point is 50°-75°. This structure prevents the disc body 1 and the tail body 2 from tearing at that point when bent, and also makes the folding process of the tail body 2 controllable, preventing short circuits in the tail body 2, thereby improving the safety performance of the battery cell.

[0044] The production process of cylindrical lithium batteries includes the step of filling the battery with electrolyte, therefore, the disc 1 needs to have holes through which the electrolyte passes. In this invention, the disc 1 is provided with a central hole 3 and at least one peripheral hole 4. The central hole 3 is located at the center of a circle, and the centers of the peripheral holes 4 are all located on a ring concentric with the central hole 3.

[0045] The number of the aforementioned peripheral holes 4 can be 3, 2, 4, or other numbers, as long as the solid area of ​​the disc 1 does not affect the welding effect with the core.

[0046] The shape of the center hole 3 is designed according to the shape of the core hole and can be circular; while the shape of the outer hole 4 can be circular or other common shapes, such as fan-shaped, bow-shaped, arc-shaped, ring-shaped, V-shaped, etc. Those skilled in the art can adjust and design it according to the needs of production and application.

[0047] In some embodiments, the peripheral hole 4 is circular, and the ratio of its diameter R1 to the diameter R2 of the central hole 3 is 0.5 < R1 / R2 < 0.7. If the diameter is too large, the welding area on the plate will be insufficient; if it is too small, it will be unfavorable for electrolyte wetting. The peripheral hole and the central hole within this range can meet the welding area requirements and facilitate electrolyte wetting.

[0048] In some embodiments, the ratio of the diameter R4 of the annulus containing the center of the outer hole 4 to the diameter R3 of the disc body 1 and the diameter R2 of the central hole 3 is R2:R4:R3 = 1:(2~2.1):(3.06~4.14). This ratio is set because the electrolyte needs a larger diameter to penetrate from the central hole, and the outer hole increases the wetting effect; while the disc body diameter is close to the core diameter to increase the contact welding area.

[0049] In some embodiments, the ratio of the minimum distance L1 from the center hole 3 to any peripheral hole 4 to the minimum distance L2 from any peripheral hole 4 to the edge of the disk body 1 is: L1:L2=1:(0.9~1.1). The above ratio is set because if the distance is too close, stress concentration will cause deformation during processing.

[0050] In some implementations, the ratio of the width of the second segment H2 to the diameter of the central hole 3 is (1.15-1.25):1; the ratio of the width of the second segment H2 to the width of the third segment H3 is 1:(1.8~2.2). The reason for this design is that the reduced width in the middle can act as a fuse when the current is abnormally high, cutting off the current and increasing battery safety.

[0051] In some embodiments, the ratio of the distance from the first bend line to the center of the disk 1 to the radius of the disk 1 is 1:(1.4~1.6). This is set in order to ensure that the whole structure is Z-shaped after installation.

[0052] like Figure 3 As shown, the thickness of the positive current collector in this invention is 0.2±0.03mm. This thickness range is designed to reduce internal resistance, improve conductivity, and increase welding reliability; if it is too thin, it is easy to burn through, and if it is too thick, it is not conducive to welding and occupies internal battery space.

[0053] The positive current collector material in this invention can be any conventional positive current collector material in the art, and this invention does not limit it.

[0054] Based on the above design of the positive current collector, this utility model can achieve a design that ensures the positive current collector is bent into a "Z" shape so that the core is as large as possible along the height direction of the shell, while the tail body 2 does not protrude from the plate body 1, thereby avoiding adverse effects on the assembly quality.

[0055] A second aspect of this invention provides a cylindrical lithium battery comprising the aforementioned positive electrode current collector, a winding core, and a cap. The positive electrode of the winding core forms a passage with the battery cap via the aforementioned positive electrode current collector. The disk body 1 is welded to the winding core, and the tail body 2 is welded to the battery cap. Because it includes the aforementioned positive electrode current collector, the cylindrical lithium battery provided by this invention also has the aforementioned beneficial effects.

[0056] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes 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 protection scope of this utility model.

Claims

1. A positive electrode current collector for a cylindrical lithium battery, characterized in that, It includes a disc body and a tail body. The disc body is a disc shape with an arc-shaped notch, and the tail body is a strip-shaped structure. The disc body is connected to the tail body through the arc-shaped notch. Along the axis of symmetry, the positive electrode current collector has a first bend line and a second bend line. The first bend line is located at the arc-shaped notch of the plate body, and the part from the highest point of the plate body to the first bend line is the first segment. The second bend line divides the tail body into a second segment and a third segment. The second segment and the third segment are connected by a chamfer, and the width of the third segment is greater than the width of the second segment. The length ratio of the first, second, and third segments is (1.5~1.7):(1.05~1.15):

1.

2. The positive current collector according to claim 1, characterized in that, The chamfer angle between the second and third segments is 30°-45°; and / or the width ratio between the second and third segments is 1:(1.8~2.2).

3. The positive current collector according to claim 2, characterized in that, The third segment has rounded chamfers at its two corners at the end furthest from the second segment, and the radius of the rounded chamfers is 0.45~0.55 mm.

4. The positive current collector according to claim 3, characterized in that, The center of the disk body is provided with a circular central hole, and at least one circular peripheral hole is provided around the central hole; The centers of the outer holes are all located on a ring concentric with the central hole, and the ratio of the diameter of the outer hole to the diameter of the central hole is 0.5-0.

7. The ratio of the diameter of the central hole to the diameter of the ring and the disk is 1:(2~2.1):(3.06~4.14).

5. The positive current collector according to claim 4, characterized in that, The ratio of the width of the second segment to the diameter of the central hole is (1.15-1.25):

1.

6. The positive current collector according to claim 5, characterized in that, The ratio of the minimum distance from the central hole to any peripheral hole to the minimum distance from any peripheral hole to the edge of the disk body is 1:(0.9~1.1).

7. The positive current collector according to claim 1, characterized in that, The circular notch of the disc is connected to the tail body by a circular arc segment, the central angle of which is 50°-75°.

8. The positive current collector according to claim 1, characterized in that, The ratio of the distance from the first bend line to the center of the disk to the radius of the disk is 1:(1.4~1.6).

9. The positive current collector according to claim 1, characterized in that, The thickness of the positive current collector is 0.2±0.03mm.

10. A cylindrical lithium battery, characterized in that, Includes the positive current collector as described in any one of claims 1-9.

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