Positive collector plate and cylindrical lithium battery

Abstract

The positive collector plate comprises a plate body and a tail body which are connected with each other, the plate body is used for being connected with a roll core pole group, and the tail body is used for being connected with a battery cap, so that a passage is formed between the roll core pole group and the battery cap; a circular center hole is formed in the center of the disc body, and at least one peripheral hole is formed in the periphery of the center hole; the shape of the disc body is an axisymmetric figure formed by sequentially connecting a first edge, an arc and a second edge. The first edge and the second edge are connected with one end of the tail body; and the first edge and the second edge respectively form two connecting angles which are bilaterally symmetrical with the two vertical edges of the tail body, and the connecting angles are 45-90 degrees. The plate body of the positive collector plate is improved, so that a gap is reserved between the bent tail body and a battery steel shell, and short circuit is prevented; and the central hole and the peripheral holes are designed on the disc body, so that a relatively large weldable area on the disc body is reserved on the premise of ensuring the safety of the battery, and the connection with a roll core pole group is facilitated.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a positive electrode current collecting disc and a cylindrical lithium battery. Background Art

[0002] Lithium batteries can be categorized by packaging type into three types: prismatic, cylindrical, and pouch. Cylindrical lithium batteries have become a hot topic in lithium battery research due to their consistent performance, high production efficiency, and robust heat dissipation capabilities. Cylindrical batteries are typically encapsulated in a cylindrical steel casing. Bare cells are manufactured using a winding process to form a cylindrical coiled electrode assembly. The cap is located on top of the battery and connected to the positive electrode in the coiled electrode assembly via a positive current collector.

[0003] Existing positive electrode collector discs for cylindrical lithium batteries consist of a disc body and a tail body, with the disc body used to connect to the wound electrode assembly. The presence of the disc body hinders electrolyte penetration efficiency. Generally, holes can be opened around the disc body to improve electrolyte penetration, but these holes can be blocked by the rubber coating, resulting in limited improvement. Furthermore, the connection between the tail body and the circular disc body is poorly designed, resulting in insufficient weldable area, affecting welding performance. Furthermore, this poorly designed connection poses the risk of the tail body shorting to the steel shell after bending, resulting in poor battery safety. Utility Model Content

[0004] To address the aforementioned issues, improve battery safety, and achieve a balance between disc welding performance and liquid permeability, the first aspect of the present application provides a positive electrode current collector disc, comprising a disc body 1 and a tail body 2, interconnected. The disc body 1 is configured to connect to a wound electrode assembly 3, and the tail body 2 is configured to connect to a battery cap, thereby forming a passageway between the wound electrode assembly 3 and the battery cap. A circular central hole 14 is provided at the center of the disc body 1, and at least one peripheral hole 15 is provided around the periphery of the central hole 14. The disc body 1 is shaped as an axially symmetrical figure consisting of a first side 11, a circular arc 12, and a second side 13, connected in sequence. The first side 11 and the second side 13 are each connected to one end of the tail body 2. The first side 11 and the second side 13 form two symmetrical connecting angles 5 with the two vertical sides 21 of the tail body 2, respectively, with the connecting angles 5 ranging from 45° to 90°. The central hole 14 and the peripheral holes 15 provide a permeation channel for the electrolyte, thereby improving the electrolyte infiltration efficiency. The shape of the disc body 1 and the specific connection between the disc tail and the disc body ensure sufficient weldable area for the disc body 1 while also increasing the distance between the bent tail body 2 and the battery steel casing 4, thereby avoiding the risk of short-circuiting between the bent tail body and the steel casing and improving battery safety. Furthermore, the design of the connection angle 5 of the present invention further facilitates bending of the tail body, and the reasonable angle range helps balance the mechanical performance of the current collector disc with the size of the disc body's weldable area.

[0005] In some optional embodiments, the area of ​​a single peripheral hole 15 is 0.3-0.5 times the area of ​​the central hole 14; and the sum of the areas of all peripheral holes 15 is 0.9-1.5 times the area of ​​the central hole 14. By limiting the area relationship between the central hole 14 and the peripheral holes 15, it is ensured that both the central hole 14 and the peripheral holes 15 can achieve corresponding penetration improvement effects while retaining a larger weldable area.

[0006] In some optional embodiments, the distance L between the center of the peripheral hole 15 and the center of the central hole 14 is 25%-35% of the diameter d of the central hole 14. By designing the spacing between the central hole 14 and the peripheral holes 15, the efficiency of electrolyte infiltration is improved, and the subsequent encapsulation process is avoided to block the peripheral holes 15.

[0007] In some optional embodiments, the peripheral holes 15 are circular holes, and the diameter dn of the circular holes is 50%-70% of the diameter d' of the central hole 14. By properly designing the area and diameter parameters of the peripheral holes 15, the weldable area is retained while improving the electrolyte infiltration effect.

[0008] In some optional embodiments, the diameter d′ of the central hole 14 is 1.4-1.8 times the diameter D′ of the winding hole 31 of the winding pole group 3 .

[0009] In some optional embodiments, the diameter d' of the center hole 14 is 25%-35% of the diameter d of the disc body 1. The center hole 14 is used to inject electrolyte. A reasonable diameter range first ensures a sufficient weldable area of ​​the disc body 1, while also improving injection efficiency and reducing potential risks during production.

[0010] In some optional embodiments, the disk body 1 has a central angle B, where 40° ≤ ∠B ≤ 60°. The central angle B has its vertex at the center of the arc 12, and its two edges pass through the endpoint of the first edge 11 away from the arc 12 and the endpoint of the second edge 13 away from the arc 12. The design of the central angle ensures that the disk body 1 still has a weldable area of ​​at least 75% after the hole is opened.

[0011] In some optional embodiments, the diameter d of the disk body 1 is 80%-95% of the diameter D of the core pole group 3 .

[0012] In some optional embodiments, at least one groove 22 is provided on the tail body 2 to provide safety protection for the positive electrode current collecting disk. When the battery thermally runs away, the groove melts, thereby cutting off the current.

[0013] A second aspect of the present application provides a cylindrical lithium battery, comprising a wound electrode assembly 3 and a battery cap. The positive electrode of the wound electrode assembly 3 forms a path between the positive electrode current collector disk and the battery cap. The disk body 1 is connected to the wound electrode assembly 3, and the tail body 2 is connected to the battery cap. Due to the aforementioned beneficial effects of the positive electrode current collector disk, the cylindrical lithium battery provided by the present application has higher production efficiency and yield, and is highly safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 This is a schematic structural diagram of a positive electrode current collecting disk according to an embodiment of the present application;

[0016] Figure 2 This is a schematic diagram of assembling a positive electrode current collecting disk in a cylindrical lithium battery according to an embodiment of the present application;

[0017] Figure 3 This is a front view of a positive electrode current collecting disk according to an embodiment of the present application;

[0018] Figure 4 This is a top view of the assembly of a positive electrode current collecting disk in a cylindrical lithium battery according to one embodiment of the present application;

[0019] Figure 5 This is a cross-sectional view of an assembly of a positive electrode current collecting disc in a cylindrical lithium battery according to an embodiment of the present application;

[0020] Figure 6 This is a schematic diagram of the structure of a positive electrode current collecting disk according to an embodiment of the present application;

[0021] Figure 7 This is a schematic diagram of the structure of a positive electrode current collecting disk according to an embodiment of the present application;

[0022] Figure 8 This is a schematic diagram of the structure of a positive electrode current collecting disk according to an embodiment of the present application;

[0023] Figure 9 This is a schematic diagram of the disk structure of the positive electrode current collecting disk of an embodiment of the present application.

[0024] Figure markings: 1-disk body, 11-first side, 12-arc, 13-second side, 14-center hole, 15-peripheral hole, 2-tail body, 21-vertical side, 22-groove, 3-core pole group, 31-core hole, 4-battery steel shell, 5-connection angle, ∠B-center angle, d-disk body diameter, D-core pole group diameter, d'-center hole diameter, D'-core hole diameter, L-distance between the center position of the peripheral hole and the center of the center hole, dn-diameter of the circular peripheral hole. DETAILED DESCRIPTION

[0025] Examples of the present embodiment are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment and are not to be construed as limiting the present embodiment.

[0026] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships 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, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this embodiment.

[0027] In the description of this embodiment, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0028] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0029] Please refer to Figure 1 and Figure 2 , Figure 1 A schematic structural diagram of a positive electrode current collecting disk according to an embodiment of the present application is shown. Figure 2The figure shows a schematic diagram of the assembly of a positive electrode current collector disk in a cylindrical lithium battery according to an embodiment of the present application. The positive electrode current collector disk includes a disk body 1 and a tail body 2, which are interconnected. The disk body 1 is used to connect to the core electrode group 3, and the tail body 2 is used to connect to the battery cap (not shown) to form a path between the core electrode group 3 and the battery cap. In the present application, the connection between the disk body 1 and the core electrode group 3, and the connection between the tail body 2 and the battery cap can be achieved by any connection method familiar to those skilled in the art, such as welding. The connection between the tail body 2 and the disk body 1 can be any fixed connection method. To ensure a stable connection and the overall strength of the current collector disk, an integral connection is preferred.

[0030] Please refer to Figure 3 , Figure 3 The figure shows a front view of a positive electrode current collector disk according to one embodiment of the present application. To match the circular cross-section of the wound electrode assembly and facilitate welding between the disk body 1 and the wound electrode assembly 3, the disk body 1 preferably has an axially symmetrical shape consisting of a first side 11, an arc 12, and a second side 13, connected in sequence. This shape can also be considered the shape remaining after cutting off two symmetrical corners about a diameter from the full circle (shown as a dashed-dotted line) containing the arc 12. It can also be considered a bow-like shape. It should be noted that due to the connection between the disk body 1 and the tail body 2, there is no connection between the first side 11 and the second side 13.

[0031] The production process of cylindrical lithium batteries includes a production step of pouring electrolyte into the battery. Therefore, a hole for the electrolyte to pass through must be left on the disc body 1. To ensure that the physical area of ​​the disc body 1 after punching still accounts for more than 75% of the total area of ​​the disc body 1 to facilitate welding with the core electrode group 3, the disc body 1 preferably has a center angle B, and 40°≤∠B≤60°; further preferably, 45°≤∠B≤55°. Specifically, the total area of ​​the above-mentioned disc body 1 is the sum of the physical area of ​​the disc body 1 and the area of ​​the hole; the center angle B takes the center point corresponding to the arc 12 as the vertex, and the two sides pass through the end point of the first side 11 away from the arc 12 and the end point of the second side 13 away from the arc 12 respectively. It can be understood that the end point of the first side 11 away from the arc 12 and the end point of the second side 13 away from the arc 12 are also the connection points of the first side 11, the second side 13 and the tail body 2.

[0032] In some embodiments, the first side 11 and the second side 12 of the disc 1 are both connected to one end of the tail 2. In actual assembly, the tail 2 requires two bends: a primary bend away from the core electrode assembly 3 and a secondary bend away from the battery casing 4, before being connected to the battery cap. Compared to connecting the tail 2 to the arc 12, connecting the tail 2 to two edges allows the tail 2 to be closer to the center of the disc 1, thereby increasing the radial distance between the tail 2 and the battery casing 4 after bending, thereby reducing the risk of short circuits.

[0033] In some embodiments, at the junction between the tail body 2 and the disk body 1, the first side 11 and the second side 13 of the disk body 1 form two symmetrical connection angles 5 with the two vertical sides 21 of the tail body 2. Preferably, the connection angles 5 are between 45° and 90°, more preferably between 60° and 80°. If the connection angles 5 are too small, the bending of the tail body 2 may cause excessive stress concentration, causing deformation or even fracture of the disk body 1. If the connection angles 5 are too large, it is impossible to ensure that the disk body 1 has a weldable area of ​​at least 75%.

[0034] See also Figure 4-6 In some embodiments, the diameter d of the disk body 1 is 80%-95% of the diameter D of the core pole group 3. The diameter d of the disk body 1 refers to the longest line segment between two points on the arc 12, and the diameter D of the core pole group 3 refers to the diameter of the circular cross-section of the core pole group 3. Depending on actual needs, the diameter d of the disk body 1 can be, for example, 15-23 mm. Within this diameter range, the disk body 1 ensures a large contact area between the disk body 1 and the core pole group 3, increasing the weldable area and broadening the adaptability of weld wire lengths and shapes.

[0035] In some embodiments, a center hole 14 is provided at the center of the disk body 1 for injecting electrolyte into the battery. The center of the disk body 1 may be the center of the circle corresponding to the arc 12. The core electrode group 3 of the cylindrical lithium battery is made by a winding process. After winding, a circular core hole 31 is formed at the center of the core electrode group 3. In order to match the shape of the core hole 31, the center hole 14 is preferably a circular hole. Further preferably, the diameter d' of the center hole 14 is 1.4-1.8 times the diameter D' of the core hole of the core electrode group; further, the diameter d' of the center hole 14 is 25%-35% of the diameter d of the disk body 1. According to actual needs, the diameter d' of the center hole 14 is, for example, 4-8 mm. Within this diameter range, the center hole 14 can achieve a balance between injection efficiency and weldable area while ensuring welding safety. If the diameter d' of the center hole 14 is too small, it will be detrimental to the infiltration of the injection liquid. Moreover, when the resistance welding process is used at the bottom of the battery, the electrode head extending into the core hole 31 of the core electrode group 3 may produce unwanted contact with the collecting disk, posing an interference risk. If the diameter d' of the center hole 14 is too large, the weldable area will be correspondingly reduced, limiting the welding process between the disk body 1 and the core electrode group 3.

[0036] In some embodiments, at least one peripheral hole 15 is provided around the central hole 14 to assist in the infiltration of the electrolyte. Specifically, the shape of the peripheral hole 15 can be circular (see Figure 3 ), fan-shaped (seen in Figure 7 ), bow, arc, ring, V-shaped (seen in Figure 8), S-shaped, T-shaped, U-shaped, X-shaped, I-shaped, waist-shaped, oblong, etc.; it can also be a polygon, such as a triangle, quadrilateral, pentagon, hexagon (seen in Figure 9 The shape of the peripheral hole 15 can be designed to allow the electrolyte to pass through in principle.

[0037] In some embodiments, the distance L between the center of the peripheral hole 15 and the center of the central hole 14 is 25%-35% of the diameter d of the disk body 1. Depending on practical needs, the distance L between the center of the peripheral hole 15 and the center of the central hole 14 can be, for example, 4.5-7 mm. If the shape of the peripheral hole 15 is simple, the center of the peripheral hole 15 can be a position commonly recognized by those skilled in the art. For example, the center of a circular hole is the center of the circle, the center of a quadrilateral is the intersection of its two diagonals, and the center of a triangle is the intersection of its three midlines. If the shape of the peripheral hole 15 is more complex or irregular, the center is the geometric center of the shape, i.e., the average position of all points within the shape. This can be determined by any method known to those skilled in the art, such as integration, discrete point method, graph segmentation method, etc., or directly calculated using software tools. Properly designing the distance L between the peripheral hole 15 and the central hole 14 helps improve electrolyte wetting while ensuring the area of ​​the weldable area. If the distance between the peripheral hole 15 and the central hole 14 is too small, the electrolyte infiltration effect cannot be significantly improved; if the distance between the peripheral hole 15 and the central hole 14 is too large, the peripheral hole 15 is too close to the edge of the disk body 1, thereby limiting the battery pack. If the pack blocks the peripheral hole 15, the electrolyte cannot be injected through the peripheral hole 15.

[0038] In some embodiments, the area of ​​a single peripheral hole 15 is 0.3-0.5 times the area of ​​the central hole 14, and the sum of the areas of all peripheral holes 15 is 0.9-1.5 times the area of ​​the central hole 14. If the area of ​​the peripheral hole 15 is too small compared to the area of ​​the central hole 14, the auxiliary wetting effect will be insignificant; if the area of ​​the peripheral hole 15 is too large, the weldable area of ​​the disk 1 will be greatly reduced, affecting the connection between the disk 1 and the core pole group 3. It is understandable that the areas of the peripheral holes 15 and the central hole 14 can be calculated according to the corresponding area formulas, for example, the area of ​​the central hole 14 S = π(d' / 2)^2. If there is no corresponding area formula for the shape of the peripheral hole 15, it can also be directly calculated using software tools.

[0039] To facilitate processing and improve yield, in a preferred embodiment, the peripheral holes 15 are circular. Furthermore, the diameter dn of the peripheral holes 15 is 50%-70% of the diameter d' of the central hole 14. For example, the diameter dn of the peripheral holes 15 is 2-4.8 mm. If the diameter dn of the peripheral holes 15 is too small, the wetting aid function will be difficult to achieve. If the diameter dn of the peripheral holes 15 is too large, the weldable area of ​​the disk body 1 will be reduced. It is understood that the number of peripheral holes 15 can be determined based on the actual welding process. The number of welding areas is n, and the number of peripheral holes 15 is n-1, where n ≥ 2.

[0040] In some embodiments, at least one groove 22 is formed on the tail body 2 to provide safety protection for the positive electrode current collecting disk. When the battery thermally runs away, the groove melts, thereby cutting off the current.

[0041] The first aspect of the present application provides a positive electrode current collector disk suitable for cylindrical lithium batteries. It has a simple design. While ensuring battery safety, the welding area between the disk body 1 and the core electrode group 3 is large, which greatly facilitates the welding process. The open hole design helps liquid penetration without affecting the welding performance of the disk body 1.

[0042] A second aspect of the present application provides a cylindrical lithium battery comprising a wound electrode assembly 3 and a battery cap. The positive electrode of the wound electrode assembly 3 forms a path between the battery cap and the positive electrode current collector disk as described above. The disk body 1 is welded to the wound electrode assembly 3, and the tail body 2 is welded to the battery cap. Due to the aforementioned beneficial effects of the positive electrode current collector disk, the cylindrical lithium battery provided by the present application has higher production efficiency and yield, and is highly safe.

[0043] Throughout this specification, references to "some embodiments," "one example," or similar descriptions indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment or example. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0044] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and intent of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A positive electrode current collector disk, comprising a disk body (1) and a tail body (2) connected to each other, wherein the disk body (1) is used to connect to a core electrode group (3), and the tail body (2) is used to connect to a battery cap, so that a passage is formed between the core electrode group (3) and the battery cap, characterized in that: A circular central hole (14) is arranged at the center of the disk body (1), and at least one peripheral hole (15) is arranged around the central hole (14); The disc body (1) is in the shape of an axially symmetrical figure consisting of a first side (11), a circular arc (12) and a second side (13) connected in sequence; the first side (11) and the second side (13) are both connected to one end of the tail body (2); the first side (11) and the second side (13) respectively form two left-right symmetrical connection angles (5) with two vertical sides (21) of the tail body (2), and the size of the connection angle (5) is 45°-90°.

2. The positive electrode current collecting disk according to claim 1, characterized in that: The area of ​​a single peripheral hole (15) is 0.3-0.5 times the area of ​​the central hole (14); the sum of the areas of all the peripheral holes (15) is 0.9-1.5 times the area of ​​the central hole (14).

3. The positive electrode current collecting disk according to claim 2, characterized in that: The distance L between the center position of the peripheral hole (15) and the center of the central hole (14) is 25%-35% of the diameter d of the disk body (1).

4. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The peripheral hole (15) is a circular hole, and the diameter dn of the circular hole is 50%-70% of the diameter d' of the central hole (14).

5. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The diameter d' of the central hole (14) is 1.4-1.8 times the diameter D' of the winding hole (31) of the winding pole group (3).

6. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The diameter d' of the central hole (14) is 25%-35% of the diameter d of the disk body (1).

7. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The disk body (1) has a center angle B, and 40°≤∠B≤60°; wherein the center angle B has the center of the circle corresponding to the arc (12) as a vertex, and two sides pass through the end point of the first side (11) away from the arc (12) and the end point of the second side (13) away from the arc (12).

8. The positive electrode current collector according to any one of claims 1 to 3, characterized in that: The diameter d of the disk body (1) is 80%-95% of the diameter D of the winding core pole group (3).

9. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: At least one groove (22) is provided on the tail body (2).

10. A cylindrical lithium battery, characterized in that: The invention comprises the wound electrode group (3) and a battery cap, wherein the positive electrode of the wound electrode group (3) forms a passage with the battery cap through the positive electrode current collecting disk as described in any one of claims 1 to 9; wherein the disk body (1) is connected to the wound electrode group (3), and the tail body (2) is connected to the battery cap.

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