Novel winding needle

Abstract

The utility model belongs to the technical field of lithium ion batteries, and particularly relates to a novel winding needle, which is used for a lithium battery winding process and comprises a winding needle main body, a clamping part of the winding needle main body is arranged at one end of the winding needle in the width direction, and the distance between the clamping part and one end of the winding needle is less than 3mm; the thickness of the winding needle main body is less than 3mm; the surface of the clamping part is in a sawtooth shape; wherein the clamping part is close to one end of the winding needle through eccentric design, so that the length of the hollow diaphragm of the core part is less than or equal to 5mm. According to the utility model, the strict requirement of the novel thermal composite pole group on the length of the hollow diaphragm of the core part is accurately met, the problem of length overrun caused by the centering of the clamping part and the larger thickness of the winding needle in the prior art is solved, and a key tool support is provided for the structure compactness and the performance optimization of the pole group.

Description

New type of coil needle Technical Field

[0001] This utility model belongs to the field of lithium-ion battery technology, specifically relating to a novel coiling needle. Background Technology

[0002] With the development of lithium battery technology, novel thermal composite electrode structures are gradually being adopted. This structure involves first bonding the separator and negative electrode sheet to form a composite through heated rolling, and then winding this composite with the positive electrode sheet to form the electrode assembly. This electrode assembly structure places stringent requirements on the length of the empty separator in the core, needing to be controlled to approximately 5mm to meet the requirements of electrode assembly compactness and performance optimization.

[0003] As shown in Figure 4, the current method for calculating the core diaphragm length of a conventional coiled needle 1 is: the sum of the distance from the clamping part 11 of the coiled needle to one end of the coiled needle and the clamping length. The clamping length is related to the thickness of the coiled needle; the thickness of a conventional coiled needle is generally 7mm, corresponding to a clamping length of approximately 8mm. Since the clamping part of the conventional coiled needle is located at the center-symmetrical position in the width direction of the electrode assembly, the core diaphragm length can be further expressed as "coiled needle circumference ÷ 4 + 8mm". Taking a common coiled needle with a circumference of approximately 100mm as an example, its core diaphragm length reaches 33mm, far exceeding the design requirement of 5mm, and cannot meet the production needs of the new thermal composite electrode assembly. Summary of the Invention

[0004] The purpose of this invention is to provide a new type of coiling needle to solve the problems existing in the prior art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a novel winding needle for use in the lithium battery winding process, comprising:

[0006] The main body of the coiling needle has a clamping part located at one end in the width direction of the coiling needle, and the distance between the clamping part and one end of the coiling needle is less than 3mm;

[0007] The thickness of the main body of the coiling needle is less than 3mm;

[0008] The surface of the clamping part is set in a sawtooth shape;

[0009] The clamping part is designed to be close to one end of the winding needle to achieve a core diaphragm length of ≤5mm.

[0010] Preferably, the distance between the clamping part and one end of the coiling needle is 2mm.

[0011] Preferably, the thickness of the needle coil body is 2mm.

[0012] Preferably, the tooth height of the sawtooth shape is 0.5-1mm and the tooth pitch is 0.8-1.5mm.

[0013] Preferably, the circumference of the main body of the needle coil is 80-120mm.

[0014] Preferably, the clamping part is formed into a sawtooth shape by machining or laser cutting.

[0015] The beneficial effects of this utility model are as follows: By setting the clamping part of the coil needle off-center and close to one end (distance ≤3mm), and reducing the thickness of the coil needle to ≤3mm, the length of the core diaphragm is significantly shortened from more than 30mm in conventional coil needles to 5mm. This precisely meets the stringent requirements of the new thermal composite electrode assembly for the length of the core diaphragm, and solves the problem of excessive length caused by the centered clamping part and the large thickness of the coil needle in the prior art. It provides key tooling support for the compact structure and performance optimization of the electrode assembly.

[0016] By employing a serrated clamping part to increase the contact area and friction with the separator, the winding needle can continue to clamp the empty separator instead of the negative electrode and separator composite while maintaining clamping stability. This completely avoids the risk of damage to the negative electrode due to bending during the winding process, effectively improves the structural integrity of the battery electrode assembly, and thus significantly improves the cycle life and safety performance of the battery, overcoming the potential quality hazards caused by clamping the electrode composite in the existing technology. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the structure of this utility model;

[0018] Figure 2 is a schematic diagram of the needle clamping part of this utility model;

[0019] Figure 3 is an enlarged view of the needle clamping part of this utility model;

[0020] Figure 4 is a schematic diagram of the existing technology. Detailed Implementation

[0021] It should be noted that, without conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0022] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, 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 on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixed connection," and "fixed connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings and preferred embodiments.

[0025] As shown in Figures 2-4, a novel type of coiling needle includes a coiling needle body 2, with a clamping part 21 disposed at one end in the width direction of the coiling needle, and the distance between the clamping part and one end of the coiling needle is less than 3mm; the thickness of the coiling needle body is less than 3mm; and the surface of the clamping part is set in a serrated shape.

[0026] The clamping part is eccentrically designed to be close to one end of the winding needle, ensuring that the core separator length is ≤5mm. The winding needle body 2 is made of metal and is elongated in shape, used in the lithium battery winding process. The clamping part 21 of the winding needle body 2 is located on one side of the electrode width direction, rather than in a traditional centrally symmetrical position. Specifically, the end closer to the winding needle body 2 is defined as the front end, and the end further away from the other end is the rear end. The distance from the front edge of the clamping part 21 to the front end of the winding needle body 2 is 2mm. The thickness of the winding needle body 2 is designed to be 2mm. Based on the correlation between the thickness of the winding needle and the clamping length, the clamping length is approximately 3mm. The surface of the clamping part 21 is machined into a serrated shape with a tooth pitch of 0.5mm and a tooth depth of 0.3mm. This increases the contact area and friction with the separator, ensuring clamping stability.

[0027] The work process is as follows:

[0028] Clamping the diaphragm: In the winding process, the winding needle body 2 clamps the single-layer diaphragm through the serrated clamping part 21. Since the clamping part 21 is eccentrically close to the front end and the distance is only 2mm, combined with the 3mm clamping length corresponding to the 2mm thickness, the initial length of the core diaphragm 3 is 2mm + 3mm = 5mm.

[0029] Winding of the electrode assembly: The diaphragm and negative electrode composite, which are pre-bonded by heated rollers, and the positive electrode are sequentially introduced into the winding area of ​​the winding needle. Starting from the eccentrically clamped empty diaphragm, the electrode and diaphragm composite are wound around the winding needle body 2 by the rotation of the winding needle to form the electrode assembly.

[0030] Electrode assembly forming: After winding, the length of the empty separator 3 in the core of the electrode assembly is strictly controlled to 5mm to meet the structural requirements of the new thermal composite electrode assembly. Since only the empty separator is clamped throughout the process, the negative electrode sheet is not subjected to clamping force, thus avoiding the bending damage problem caused by traditional clamping composites.

[0031] In the above embodiments, by precisely controlling the eccentric distance of the clamping part 21, the thickness of the coil needle body 2, and the serrated structure, the precise control of the length of the core separator 3 is achieved, and the battery performance reliability is improved by the non-contact clamping electrode design. Those skilled in the art can adaptively adjust specific dimensional parameters such as the coil needle circumference and clamping distance according to different electrode group size requirements, while maintaining the eccentric setting of the clamping part 21, the thickness <3mm, and the serrated structure. All of these adjustments fall within the protection scope of this utility model.

[0032] For those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A novel winding needle for use in the lithium battery winding process, characterized in that, It includes: a coil needle body, the clamping part of which is located at one end in the width direction of the coil needle, and the distance between the clamping part and the end of the coil needle is less than 3mm; the thickness of the coil needle body is less than 3mm; the surface of the clamping part is set in a sawtooth shape; wherein, the clamping part is close to the end of the coil needle by an eccentric design to achieve a core diaphragm length ≤5mm.

2. The novel coiled needle according to claim 1, characterized in that, The distance between the clamping part and one end of the coiling needle is 2mm.

3. The novel coiled needle according to claim 1, characterized in that, The thickness of the main body of the needle coil is 2mm.

4. The novel coiled needle according to claim 1, characterized in that, The tooth height of the sawtooth shape is 0.5-1mm, and the tooth pitch is 0.8-1.5mm.

5. The novel coiled needle according to claim 1, characterized in that, The circumference of the main body of the needle coil is 80-120mm.

6. The novel coiling needle according to any one of claims 1 to 5, characterized in that, The clamping part is formed into a sawtooth shape by machining or laser cutting.

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