A winding needle and winding device for lithium ion batteries

Abstract

This utility model relates to the field of battery manufacturing technology, and in particular to a winding needle and winding device for lithium-ion batteries. The device includes a fixed platform, a support shaft, and a needle body. The needle body comprises a first section and a second section. The first section is connected to the support shaft. A plurality of first protrusions are formed at equal intervals along the axial direction on the outer wall of the first section. A plurality of second protrusions are formed at equal intervals along the axial direction on the outer wall of the second section. The distance between two adjacent first protrusions is smaller than the distance between two adjacent second protrusions, and the major axis radius of the first protrusion is smaller than the major axis radius of the second protrusion. The winding needle of this utility model can reduce the spiral phenomenon during winding of cylindrical lithium-ion batteries, improve the consistency of positive and negative electrode coating, and improve the unevenness of the upper and lower end faces caused by spiraling during winding of cylindrical lithium-ion batteries, significantly improving the production yield and appearance of cylindrical lithium-ion batteries.

Description

Technical Field

[0001] This utility model relates to the field of battery manufacturing technology, and in particular to a winding needle and winding device for lithium-ion batteries. Background Technology

[0002] With the rapid development of lithium-ion battery technology, users have also placed higher demands on the fast charging capability and capacity of lithium-ion batteries. In existing technologies, separators and electrodes are stacked and wound on a winding needle to form a core, and then the winding needle is pulled out of the core and pressed into place.

[0003] When conventional needle winding is used to wind cylindrical lithium-ion batteries, the contact area between the needle winding and the separator and the electrode is relatively large. When winding cylindrical cells with a small winding height (especially for ultra-small lithium-ion batteries used in headphones), the large contact area between the needle winding and the separator results in a large stress distribution in the separator. When the needle winding is pulled out, it is easy for it to slip and move with the needle, which will further cause the electrode to slip and misalign. Utility Model Content

[0004] In view of this, the purpose of this utility model is to provide a winding needle and winding device for lithium-ion batteries, which can effectively reduce the contact area between the winding needle and the separator, thereby significantly improving the problem of winding core pulling defects and significantly improving the yield of the winding process.

[0005] This utility model solves the above-mentioned technical problems through the following technical means:

[0006] In a first aspect, this utility model provides a coiling needle for lithium-ion batteries, comprising a fixed platform, a support shaft, and a needle body connected in sequence. The needle body includes a first segment and a second segment connected together. The first segment is connected to the support shaft. A plurality of first protrusions are formed at equal intervals along the axial direction on the outer wall of the first segment. A plurality of second protrusions are formed at equal intervals along the axial direction on the outer wall of the second segment. The distance between two adjacent first protrusions is smaller than the distance between two adjacent second protrusions. The width dimension of each first protrusion in contact with the first segment is smaller than the width dimension of each second protrusion in contact with the second segment.

[0007] In conjunction with the first aspect, in some embodiments, the length of the first segment is S1, the length of the second segment is S2, and the height of the battery cell to be wound is denoted as h. It is necessary to satisfy S1 < S2 and S1 + S2 ≥ xh, where x is an integer and satisfies x ≥ 1.

[0008] In conjunction with the first aspect, in some implementations, when the battery cell to be wound is a tabless cylindrical battery cell, it is necessary to satisfy S1+S2=h.

[0009] In conjunction with the first aspect, in some implementations, when the battery cell to be wound is a cylindrical battery cell with tabs, it is necessary to satisfy S1+S2>xh, where x is an integer greater than 1.

[0010] In conjunction with the first aspect, in some implementations, the exposed height of the tabs of the cylindrical battery cell containing the tabs is denoted as L, which must satisfy: h+6L≧S1+S2≧h+2L.

[0011] In conjunction with the first aspect, in some embodiments, the length of the first segment S1 = 1 / 3h, and the length of the second segment S2 = 2 / 3h.

[0012] In conjunction with the first aspect, in some embodiments, the width dimension of each of the second protrusions in contact with the second segment is smaller than the maximum diameter dimension of the needle body.

[0013] In conjunction with the first aspect, in some embodiments, the mounting platform has a mounting slot.

[0014] In conjunction with the first aspect, in some embodiments, the first segment and the second segment are integrally formed, and both the first protrusion and the second protrusion are semi-elliptical protrusions.

[0015] Secondly, this utility model also provides a winding device, including a winding needle for lithium-ion batteries as described in the first aspect above.

[0016] This utility model discloses a lithium-ion battery winding needle. On the one hand, it features two semi-ellipses of different sizes on the needle body. While ensuring the supporting function of the winding needle, the point-to-surface contact method effectively reduces the contact area between the winding needle and the separator, thereby significantly improving the problem of winding core pulling defects and significantly increasing the yield of the winding process. On the other hand, the distance between two adjacent first protrusions is smaller than the distance between two adjacent second protrusions, meaning that the first protrusions are more densely distributed than the second protrusions. The densely arranged first protrusions provide stable support for the core structure, preventing excessive stress concentration in the separator and electrode sheets during the initial winding state, which could lead to asymmetry in the core structure. The sparsely arranged second protrusions provide indirect stable support. At the same time, due to the smaller point-to-surface contact, it significantly improves the problem of slippage and misalignment of the separator and electrode sheets (spiral core pulling) caused by the winding needle being pulled out after winding.

[0017] This invention relates to a lithium-ion battery winding needle, which can reduce the spiral phenomenon during winding of cylindrical lithium-ion batteries, improve the uniformity of positive and negative electrode coating, and mitigate the unevenness of the upper and lower end faces caused by spiral winding of cylindrical lithium-ion batteries, significantly improving the production yield and appearance of cylindrical lithium-ion batteries. Using this invention's winding needle can also further improve the consistency of the electrochemical performance of lithium-ion batteries. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the structure of the winding needle for lithium-ion batteries according to this utility model. Figure 1 ;

[0019] Figure 2 This is a schematic diagram of the structure of the winding needle for lithium-ion batteries according to this utility model. Figure 2 ;

[0020] The components include a fixed platform 100, a mounting groove 110, a support shaft 200, a first section 310, a first protrusion 311, a second section 320, and a second protrusion 321. Detailed Implementation

[0021] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can understand the advantages and effects of this utility model from the content disclosed in this specification. It should be noted that the illustrations provided in the following embodiments are for illustrative purposes only and represent schematic diagrams, not actual pictures. They should not be construed as limiting the utility model. To better illustrate the embodiments of this utility model, some components in the figures may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable that some well-known structures and their descriptions may be omitted in the figures for those skilled in the art.

[0022] In the figures of this utility model embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figure, 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 component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe the positional relationship in the figure are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above-mentioned terms can be understood according to the specific circumstances.

[0023] like Figure 1 and Figure 2As shown, a lithium-ion battery coiling needle of this application includes a fixed platform 100, a support shaft 200, and a needle body connected in sequence. The needle body includes a first segment 310 and a second segment 320 connected together. The first segment 310 is connected to the support shaft 200. A plurality of first protrusions 311 are formed at equal intervals along the axial direction on the outer wall of the first segment 310. A plurality of second protrusions 321 are formed at equal intervals along the axial direction on the outer wall of the second segment 320. The distance between two adjacent first protrusions 311 is smaller than the distance between two adjacent second protrusions 321. Along the axial direction of the needle body, the width dimension of each first protrusion 311 in contact with the first segment 310 is smaller than the width dimension of each second protrusion 321 in contact with the second segment 320; that is, at the same horizontal position along the axial direction of the needle body, the width dimension of the first protrusion 311 is smaller than the width dimension of the second protrusion 321.

[0024] The fixed platform 100, support shaft 200, and needle body are sequentially fixedly connected. One side of the fixed platform 100 has a mounting groove 110 for fixing the needle of this application onto the winding device. The bottom of the mounting groove 110 is flush with one outer wall of the support shaft 200. The support shaft 200 stabilizes the entire needle body structure, reduces the core jump amplitude during winding, prevents the risk of needle breakage, and extends the needle's service life. The first section 310 and the second section 320 are integrally formed, and both the first protrusion 311 and the second protrusion 321 are semi-elliptical protrusions.

[0025] Let S1 denote the length of the first segment 310, S2 denote the length of the second segment 320, and h denote the height of the cell to be wound. The following conditions must be met: S1 < S2 and S1 + S2 ≥ xh, where x is an integer and x ≥ 1. When x is 1, i.e., S1 + S2 = h, this applies to tablessless cylindrical cells; when x is an integer greater than 1, it applies to cylindrical cells with tabs. The specific application can be determined based on the exposed tab height (L). Specifically, when winding cylindrical lithium-ion battery cells with tabs, to address the issue of excessive needle length causing excessive core bounce during winding, the relationship between needle length and core height is further defined as follows:

[0026] h+6L≧S1+S2≧h+2L.

[0027] In this application, the length S1 of the first segment 310 is 1 / 3h, the length S2 of the second segment 320 is 2 / 3h, one-third of the core height is on the first segment 310, and two-thirds of the core height is on the second segment 320. Along the axial direction of the needle body, on the horizontal plane where the second protrusion 321 contacts the second segment 320, the width of the contact area between the second protrusion 321 and the second segment 320 is smaller than the maximum diameter r of the needle body. The distribution density of the first protrusions 311 on the first segment 310 is relatively concentrated, and the distance between two adjacent first protrusions 311 is less than or equal to the width of the contact area between the first protrusion 311 and the first segment 310; the distribution density of the second protrusions 321 on the second segment 320 is relatively sparse, and the distance between two adjacent second protrusions 321 is less than or equal to the width of the contact area between the second protrusion 321 and the second segment 320.

[0028] When lithium-ion batteries are wound into cylindrical cell structures using the pin winding method of this application, the winding yield is as high as about 95%, while the yield of conventional pin winding is only about 83%.

[0029] The lithium-ion battery winding needle of this invention has two main features. First, it features two semi-elliptical protrusions with different major axis radii on the needle body. While ensuring the supporting function of the winding needle, the point-to-surface contact method effectively reduces the contact area between the winding needle and the separator, thereby significantly improving the problem of core pulling during winding and significantly increasing the yield of the winding process. Second, the distance between two adjacent first protrusions 311 is smaller than the distance between two adjacent second protrusions 321, meaning that the first protrusions 311 are more densely distributed than the second protrusions 321. The densely arranged first protrusions 311 provide stable support for the core structure, preventing excessive stress concentration in the separator and electrode sheets during the initial winding state, which could lead to asymmetry in the core structure. The sparsely arranged second protrusions 321 provide indirect stable support. At the same time, due to the smaller point-to-surface contact, it can significantly improve the problem of slippage and misalignment of the separator and electrode sheets (spiral core pulling) caused by the pulling out of the winding needle after winding.

[0030] An embodiment of this application also provides a winding device, which includes the above-mentioned lithium-ion battery winding needle, which is mounted on the winding device through a mounting groove.

[0031] The above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model. Technologies, shapes, and structural parts not described in detail in this utility model are all known technologies.

Claims

1. A winding needle for lithium-ion batteries, characterized in that, The device includes a fixed platform, a support shaft, and a needle body connected in sequence. The needle body includes a first segment and a second segment connected together. The first segment is connected to the support shaft. The outer wall of the first segment has a plurality of first protrusions formed at equal intervals along the axial direction. The outer wall of the second segment has a plurality of second protrusions formed at equal intervals along the axial direction. The distance between two adjacent first protrusions is smaller than the distance between two adjacent second protrusions. The width dimension of each first protrusion in contact with the first segment is smaller than the width dimension of each second protrusion in contact with the second segment.

2. The coiling needle for a lithium-ion battery according to claim 1, characterized in that, The length of the first segment is S1, the length of the second segment is S2, and the height of the battery cell to be wound is denoted as h. It is necessary to satisfy S1 < S2 and S1 + S2 ≥ xh, where x is an integer and satisfies x ≥ 1.

3. The coiling needle for a lithium-ion battery according to claim 2, characterized in that, When the battery cell to be wound is a tabless cylindrical battery cell, it is necessary to satisfy S1+S2=h.

4. A coiling needle for a lithium-ion battery according to claim 2, characterized in that, When the battery cell to be wound is a cylindrical battery cell with tabs, it must satisfy S1+S2>xh, where x is an integer greater than 1.

5. A coiling needle for a lithium-ion battery according to claim 4, characterized in that, Let L be the exposed height of the tabs of a cylindrical battery cell containing tabs. It must satisfy the following condition: h+6L≧S1+S2≧h+2L.

6. A coiling needle for a lithium-ion battery according to claim 2, characterized in that, The length of the first segment is S1 = 1 / 3h, and the length of the second segment is S2 = 2 / 3h.

7. A coiling needle for a lithium-ion battery according to claim 1, characterized in that, The width of each second protrusion in contact with the second segment is less than the maximum diameter of the needle body.

8. A coiling needle for a lithium-ion battery according to claim 1, characterized in that, The mounting platform has a mounting slot.

9. A winding needle for a lithium-ion battery according to claim 1, characterized in that, The first segment and the second segment are integrally formed, and both the first protrusion and the second protrusion are semi-elliptical protrusions.

10. A winding device, characterized in that, Including the lithium-ion battery coiling needle as described in any one of claims 1-9.

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