Electrode assembly and secondary battery
Patent Information
- Application Number
- CN202522208762.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-17
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2035-10-17
AI Technical Summary
[0003]本实用新型提供一种电极组件及二次电池，以解决卷绕体平直区的上表面容易产生褶皱等技术问题
[0014]本实用新型的有益效果：本实用新型提供的一种电极组件及二次电池，其卷绕体在置于压制工装进行压制时，电极组件的厚度方向可以沿竖直方向放置，并使第一极片的尾端位于卷绕体的上方，也即第一极片的尾端在竖直方向上，更靠近压制工装的上压板。平直区沿卷绕体的宽度方向的尺寸为D，第一极片的尾端与所述第一弧形区之间沿卷绕体的宽度方向的距离为d，由于0.3≤d/D≤0.8，因此，第一极片的尾端所在层的重量小于完整的一层第一极片的重量，在层数保持一致的情况下，使得卷绕体平直区靠上的部分的整体重量得以降低。平直区靠上的部分重量降低，特别是D≥230mm的情况下，有利于避免平直区靠上的部分受自重的影响而下塌乃至产生冗余，因此有利于避免卷绕体在压制后在卷绕体的上表面产生如褶皱等缺陷，提高电极组件的良品率。
Smart Images
Figure CN224803932U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of secondary battery technology, and in particular to an electrode assembly and a secondary battery. Background Technology
[0002] The electrode assembly of a secondary battery typically includes a positive electrode, a negative electrode, and a separator. The positive electrode, negative electrode, and separator are formed into a flat wound body through processes such as winding and pressing. After pressing, wrinkles and other defects are easily generated on the upper surface of the flat area of the wound body, affecting the quality of the electrode assembly and the battery. Summary of the Invention
[0003] This invention provides an electrode assembly and a secondary battery to solve the technical problem of wrinkles easily forming on the upper surface of the straight area of the wound body.
[0004] The present invention provides an electrode assembly, including a first electrode and a second electrode, wherein the first electrode and the second electrode are wound to form a flat wound body, and along the thickness direction of the wound body, both surfaces of the second electrode are disposed opposite to the first electrode. The winding body includes a flat region and a first arc-shaped region and a second arc-shaped region respectively connected to the two ends of the flat region along the width direction of the winding body. The tail end of the first electrode is wound from the first arc-shaped region to the flat region, and the tail end of the first electrode is located in the flat region. The dimension of the straight area along the width direction of the winding body is D, and the distance between the tail end of the first electrode and the first arc-shaped area along the width direction of the winding body is d, where D≥230mm and 0.3≤d / D≤0.8.
[0005] In one embodiment of this application, the winding body has a winding center, and the straight region includes a first straight portion and a second straight portion located on both sides of the winding center, the first end of the first electrode is located in the second straight portion, and the tail end of the first electrode is located in the first straight portion.
[0006] In one embodiment of this application, the wound body has a plurality of tabs, each of which extends from the second straight portion.
[0007] In one embodiment of this application, the winding body has a plurality of tabs, some of which extend from the first straight portion and others extend from the second straight portion, wherein the number of tabs extending from the second straight portion is greater than the number of tabs extending from the first straight portion.
[0008] In one embodiment of this application, along the thickness direction of the wound body, the first straight portion includes an outer layer region and an inner layer region that is closer to the winding center of the wound body than the outer layer region, and the tabs of the first straight portion extend from the inner layer region.
[0009] In one embodiment of this application, the flat area is divided into a first half-region and a second half-region that are equal in width direction along the winding body. The first half-region is connected to the first arc-shaped region, and the second half-region is connected to the second arc-shaped region. The first end of the first electrode is located in the second half-region, and the tail end of the first electrode is located in the first half-region.
[0010] In one embodiment of this application, the first end of the first electrode sheet is closer to the second arc-shaped region along the width direction of the winding body, relative to the middle part of the straight region along the width direction of the winding body; the tail end of the first electrode sheet is closer to the first arc-shaped region along the width direction of the winding body, relative to the middle part of the straight region along the width direction of the winding body.
[0011] In one embodiment of this application, the distance between the first end of the first electrode and the second arc-shaped region along the width direction of the winding body is 20mm to 50mm, and the distance between the tail end of the first electrode and the first arc-shaped region along the width direction of the winding body is 20mm to 50mm.
[0012] In one embodiment of this application, an insulating protective layer is provided at the first end and the last end of the first electrode.
[0013] This utility model also provides a secondary battery, including a housing, wherein the electrode assembly as described in any of the preceding claims is disposed within the housing.
[0014] The beneficial effects of this utility model are as follows: The electrode assembly and secondary battery provided by this utility model allow the electrode assembly to be placed vertically in the thickness direction when its wound body is pressed using a pressing fixture. The tail end of the first electrode sheet is positioned above the wound body, meaning it is closer to the upper pressure plate of the pressing fixture in the vertical direction. The dimension of the flat area along the width direction of the wound body is D, and the distance between the tail end of the first electrode sheet and the first arc-shaped area along the width direction of the wound body is d. Since 0.3 ≤ d / D ≤ 0.8, the weight of the layer containing the tail end of the first electrode sheet is less than the weight of a complete layer of the first electrode sheet. With the number of layers remaining the same, the overall weight of the upper part of the flat area of the wound body is reduced. This weight reduction, especially when D ≥ 230 mm, helps prevent the upper part of the flat area from collapsing or becoming redundant due to its own weight. Therefore, it helps avoid defects such as wrinkles on the upper surface of the wound body after pressing, improving the yield of the electrode assembly. Attached Figure Description
[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0016] In the attached diagram: Figure 1 This is a cross-sectional schematic diagram of the wound body in one embodiment of the present invention; Figure 2 This is a schematic diagram showing the dimensions of the wound body in one embodiment of the present invention; Figure 3 This is a schematic diagram of the first straight portion and the second straight portion in one embodiment of the present invention; Figure 4 This is one of the schematic diagrams showing the position of the electrode tab in one embodiment of this utility model; Figure 5 This is a second schematic diagram showing the position of the electrode tab in one embodiment of this utility model; Figure 6 This is a schematic diagram of the first half-region and the second half-region in one embodiment of the present invention.
[0017] The reference numerals in the attached figures are as follows: First electrode 1, Second electrode 2, First straight portion 3, Second straight portion 4, First arc-shaped region 5, Second arc-shaped region 6, First half region 7, Second half region 8, Straight region 9, Winding center 10, First end of the first electrode 11, Tail end of the first electrode 12, Outer layer region 13, Inner layer region 14, Negative electrode tab 15, Positive electrode tab 16, First end of the second electrode 21, Tail end of the second electrode 22, Winding direction R, Thickness direction T, Width direction W. Detailed Implementation
[0018] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0019] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0020] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.
[0021] Please see Figures 1-6 This embodiment provides an electrode assembly, including a first electrode 1 and a second electrode 2. The first electrode 1 and the second electrode 2 are wound along a winding direction R to form a flat wound body. The wound body has a thickness direction T and a width direction W. The wound body is a flattened shape formed by pressing. There is a large plane on each side of the wound body. The thickness direction T of the wound body is also the pressing direction of the wound body and is perpendicular to the large plane of the wound body. The wound body is wound around a winding axis. The width direction W of the wound body is perpendicular to the thickness direction T and the winding axis direction of the wound body.
[0022] Along the thickness direction T of the wound body, both surfaces of the second electrode 2 are positioned opposite to the first electrode 1. That is, after the first electrode 1 and the second electrode 2 are wound, the second electrode 2 is sandwiched between the first electrode 1, while the outermost electrode of the wound body is the first electrode 1.
[0023] In this embodiment, the first electrode 1 is a negative electrode and the second electrode 2 is a positive electrode. The first electrode 1 is the outermost electrode of the wound body and uses more material. Compared with the positive electrode, the material price of the negative electrode is relatively low. Therefore, the first electrode 1 is a negative electrode, which helps to reduce the cost of the electrode assembly.
[0024] In this embodiment, the first electrode 1 is the negative electrode, and the second electrode 2 is the positive electrode. Compared to the positive electrode, the negative electrode has a lower material cost. The tab electrode is sandwiched between the first electrode 1, meaning the second electrode 2 is shorter, which helps reduce the overall cost of the motor assembly. In this embodiment, the winding body is gradually wound in the direction R from the first end 11 of the first electrode and the first end 21 of the second electrode towards the tail end 12 of the first electrode and the tail end 22 of the second electrode. The first end 11 of the first electrode and the first end 21 of the second electrode are located in the inner circle of the winding body, and the tail end 12 of the first electrode and the tail end 22 of the second electrode are located in the outer circle of the winding body.
[0025] Along the width direction W of the winding body, the winding body includes a first arc-shaped region 5, a straight region 9 and a second arc-shaped region 6. The first arc-shaped region 5 and the second arc-shaped region 6 are respectively connected to the two ends along the width direction W of the winding body. The tail end 11 of the first electrode is wound from the first arc-shaped region 5 to the straight region 9 along the winding direction R. The tail end 12 of the first electrode is located in the straight region 9.
[0026] The tail end 11 of the first electrode is the part of the first electrode 1 that is close to the tail end and located in the flat region 9. After the part of the first electrode 1 that is close to the tail end is wound through the first arc region 5, it enters the flat region 9 and extends in the width direction W of the wound body within the flat region 9.
[0027] like Figure 2 As shown, the dimension of the flat region 9 along the width direction W of the winding body is D, and the distance between the tail end 12 of the first electrode and the first arc-shaped region 5 along the width direction W of the winding body is d, where D ≥ 230 mm and 0.3 ≤ d / D ≤ 0.8. The distance d between the tail end 12 of the first electrode and the first arc-shaped region 5 along the width direction W of the winding body refers to the distance between the tail end 12 of the first electrode and the connection point between the first arc-shaped region 5 and the flat region 9, along the width direction W of the winding body; that is, the dimension of the tail end 11 of the first electrode along the width direction W of the winding body. The connection point between the first arc-shaped region 5 and the flat region 9 is also the tangent position between the outer arc surface of the first arc-shaped region 5 and the flat surface of the flat region 9.
[0028] For flat wound materials, after winding, they typically require pressing using processes such as hot pressing. A typical pressing fixture usually includes an upper and lower pressure plate positioned vertically. During pressing, the wound material is placed between the upper and lower pressure plates, with the thickness direction T of the wound material pointing in the pressing direction, meaning T is aligned with the vertical direction. After the wound material is in place, the upper and lower pressure plates close together to press it.
[0029] When the wound body is pressed by the pressing fixture, the tail end 12 of the first electrode sheet is positioned above the wound body, that is, the tail end 12 of the first electrode sheet is closer to the upper pressure plate of the pressing fixture in the vertical direction. The dimension of the flat area 9 along the width direction W of the wound body is D, and the distance between the tail end 12 of the first electrode sheet and the first arc-shaped area 5 along the width direction W of the wound body is d. When D≥230mm, during the pressing process of the wound body, the weight of the upper part of the flat area 9 in the vertical direction is relatively large. Since d / D≤0.8 in this embodiment, the weight of the layer where the tail end 12 of the first electrode sheet is located is less than the weight of a complete layer of the first electrode sheet 1. With the number of layers remaining the same, the overall weight of the upper part of the flat area 9 of the wound body is reduced. The reduction in weight of the upper part of the flat area 9 helps to prevent the upper part of the flat area 9 from collapsing or even becoming redundant due to its own weight. This, in turn, helps to prevent defects such as wrinkles from forming on the upper surface of the wound body after pressing, thereby improving the yield of the electrode assembly. Meanwhile, since d / D≥0.3, the upper pressure plate can effectively press down the tail end 12 of the first electrode sheet during the pressing process, which helps to maintain the tension of the winding body during the pressing process and prevent the winding body from becoming loose.
[0030] Specifically, in this embodiment, the first end 11 of the first electrode sheet is closer to the second arc-shaped region 6 along the width direction W of the winding body, relative to the middle of the flat region 9 along the width direction W of the winding body. The last end 12 of the first electrode sheet is closer to the first arc-shaped region 5 along the width direction W of the winding body, relative to the middle of the flat region 9 along the width direction W of the winding body. That is, the position of the last end 12 of the first electrode sheet is located on the side closer to the first arc-shaped region 5 in the middle of the first flat portion 3 along the width direction W. Since the portion of the first electrode sheet 1 near the last end is wound from the first arc-shaped region 5 to the second arc-shaped region 6, the dimension of the portion of the first electrode sheet 1 near the last end within the flat region 9 is relatively short, which is beneficial to further reduce the overall weight of the upper part of the flat region 9 of the winding body.
[0031] Specifically, in this embodiment, the distance between the first end 11 of the first electrode and the second arc-shaped region 6 along the width direction W of the winding body is 20mm to 50mm, and the distance between the tail end 12 of the first electrode and the first arc-shaped region 5 along the width direction W of the winding body is 20mm to 50mm.
[0032] The distance between the first end 11 of the first electrode and the second arc-shaped region 6 along the width direction W of the winding body refers to the distance between the first end 11 of the first electrode and the connection point between the second arc-shaped region 6 and the straight region 9, along the width direction W of the winding body. The connection point between the second arc-shaped region 6 and the straight region 9 is also the tangent point between the outer arc surface of the second arc-shaped region 6 and the straight surface of the straight region 9.
[0033] In practice, the wound body has a winding center 10, and the wound body is wound around the winding center 10. For example... Figure 1 and Figure 5 As shown, in this embodiment, the flat region 9 includes a first flat portion 3 and a second flat portion 4 located on both sides of the winding center 10, the first end 11 of the first electrode is located in the first flat portion 3, the tail end 12 of the first electrode is located in the second flat portion 4, and the first end 11 and the tail end 12 of the first electrode are located on both sides of the winding center 10.
[0034] Since the first end 11 of the first electrode is located in the second straight section 4, the lower pressure plate supports the second straight section 4 and the first end 11 of the first electrode in the second straight section 4. Compared to the first straight section 3, the first end 11 of the first electrode is located in the second straight section 4, which can prevent the first end 11 of the first electrode from falling off or shifting due to gravity during the pressing process. This makes the first electrode 1 in the inner circle of the winding body more neat and attached after pressing, reducing the risk of lithium plating and thus improving the reliability of the electrode assembly.
[0035] like Figure 1 , Figure 4 and Figure 5 As shown, the wound body has multiple tabs, including a negative tab 15 and a positive tab 16. The negative tab 15 extends from the negative electrode plate (first electrode plate 1), and the positive tab 16 extends from the positive electrode plate (second electrode plate 2).
[0036] like Figure 4 As shown, in some embodiments, each tab extends from the second straight portion 4. During the pressing of the winding body, the second straight portion 4 is placed on the lower pressure plate, and each tab extends from the second straight portion 4. That is, the weight of the tabs is borne by the second straight portion 4, which helps to reduce the weight of the first straight portion 3, thereby reducing the risk of the first straight portion 3 collapsing due to its own weight.
[0037] like Figure 5 As shown, in some embodiments, some tabs extend from the first straight portion 3. Another portion of the tabs extend from the second straight portion 4. The number of tabs extending from the first straight portion 3 is greater than the number extending from the second straight portion 4, resulting in a more uniform distribution of the tabs. This also increases the space and number of tabs available for installation, reduces the overall internal resistance of the electrode assembly tabs, and improves product performance. Furthermore, the greater number of tabs extending from the second straight portion 4 than from the first straight portion 3 means that during winding and pressing, the second straight portion 4 is placed on the lower pressure plate, with most of the weight of the tabs borne by the second straight portion 4 and a smaller portion borne by the first straight portion 3. This reduces the risk of the first straight portion 3 collapsing due to its own weight.
[0038] In this embodiment, along the thickness direction T of the wound body, the second straight portion 4 includes an outer layer region 13 and an inner layer region 14 that is closer to the winding center 10 of the wound body than the outer layer region 13. The electrode tab of the second straight portion 4 extends from the inner layer region 14. The electrode tab extending from the first straight portion 3 is located in the inner layer region 14, that is, the electrode tab extending from the first straight portion 3 is set closer to the second straight portion 4, which is beneficial to the connection between the electrode tab of the first straight portion 3 and the electrode tab of the second straight portion 4, and simplifies the electrode assembly structure.
[0039] like Figure 6 As shown, in this embodiment, the flat area 9 is divided into a first half-area 7 and a second half-area 8 that are equal in width direction W of the winding body. The first half-area 7 is connected to the first arc-shaped area 5, and the second half-area 8 is connected to the second arc-shaped area 6. The first end 11 of the first electrode is located in the second half-area 8, and the tail end 12 of the first electrode is located in the first half-area 7.
[0040] Since the tail end 12 of the first electrode is closer to the first arc-shaped region 5 along the width direction W of the winding body than the second arc-shaped region 6, and the head end 11 of the first electrode is located in the second half region 8, the head end 11 and the tail end 12 of the first electrode are located in the first half region 7 and the second half region 8 respectively, making the end distribution of the first electrode 1 more uniform. The head end 11 and the tail end 12 of the first electrode are both avoided at the midpoint of the winding body along the width direction W, making the surface of the electrode assembly flatter after pressing. This helps to reduce the internal stress of the winding body caused by the concentrated position of the head end 11 and the tail end 12 of the first electrode, thereby improving the reliability of the electrode assembly.
[0041] In this embodiment, an insulating protective layer is provided at the first end 11 and the last end 12 of the first electrode. The insulating protective layer serves as insulation protection. During the cutting process of the first electrode 1, burrs are easily left at the first end 11 and the last end 12 of the first electrode. Covering the first end 11 and the last end 12 of the first electrode with the insulating protective layer helps to prevent burrs from piercing the diaphragm and improves the reliability of the product.
[0042] This embodiment also provides a secondary battery, including a housing, within which an electrode assembly as described in any of the preceding embodiments is disposed. The housing protects the electrode assembly, and the tabs of the electrode assembly are connected to a structure of the housing, such as a terminal post, to supply power to the outside.
[0043] In summary, the electrode assembly and secondary battery provided in this embodiment allow the electrode assembly to be placed vertically in the thickness direction T when its wound body is pressed by a pressing fixture, with the tail end 12 of the first electrode sheet positioned above the wound body. That is, the tail end 12 of the first electrode sheet is closer to the upper pressure plate of the pressing fixture in the vertical direction. The dimension of the flat region 9 along the width direction W of the wound body is D, and the distance between the tail end 12 of the first electrode sheet and the first arc-shaped region 5 along the width direction W of the wound body is d. Since 0.3 ≤ d / D ≤ 0.8, the weight of the layer containing the tail end 12 of the first electrode sheet is less than the weight of a complete layer of the first electrode sheet 1. With the number of layers remaining the same, the overall weight of the upper part of the flat region 9 of the wound body is reduced. The weight of the upper part of the flat zone 9 is reduced, especially when D≥230mm. This helps to prevent the upper part of the flat zone 9 from collapsing or becoming redundant due to its own weight. Therefore, it helps to avoid defects such as wrinkles on the upper surface of the winding body after pressing, and improves the yield of the electrode assembly.
[0044] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.
Claims
1. An electrode assembly, characterized in that, It includes a first electrode and a second electrode, the first electrode and the second electrode are wound to form a flat wound body, and along the thickness direction of the wound body, both surfaces of the second electrode are disposed opposite to the first electrode; The winding body includes a flat region and a first arc-shaped region and a second arc-shaped region respectively connected to the two ends of the flat region along the width direction of the winding body. The tail end of the first electrode is wound from the first arc-shaped region to the flat region, and the tail end of the first electrode is located in the flat region. The dimension of the straight area along the width direction of the winding body is D, and the distance between the tail end of the first electrode and the first arc-shaped area along the width direction of the winding body is d, where D≥230mm and 0.3≤d / D≤0.
8.
2. The electrode assembly according to claim 1, characterized in that, The winding body has a winding center, and the straight area includes a first straight portion and a second straight portion located on both sides of the winding center, the first end of the first electrode is located in the second straight portion, and the tail end of the first electrode is located in the first straight portion.
3. The electrode assembly according to claim 2, characterized in that, The wound body has multiple tabs, each of which extends from the second straight portion.
4. The electrode assembly according to claim 2, characterized in that, The winding body has multiple tabs, some of which extend from the first straight portion and others from the second straight portion. The number of tabs extending from the second straight portion is greater than the number of tabs extending from the first straight portion.
5. The electrode assembly according to claim 4, characterized in that, Along the thickness direction of the wound body, the first straight portion includes an outer layer region and an inner layer region that is closer to the winding center of the wound body than the outer layer region, and the tabs of the first straight portion extend from the inner layer region.
6. The electrode assembly according to claim 1, characterized in that, The straight section is divided into a first half-section and a second half-section that are equal in width along the winding body. The first half-section is connected to the first arc-shaped section, and the second half-section is connected to the second arc-shaped section. The first end of the first electrode is located in the second half-section, and the tail end of the first electrode is located in the first half-section.
7. The electrode assembly according to claim 6, characterized in that, The first end of the first electrode sheet is closer to the second arc-shaped region along the width direction of the winding body, relative to the middle of the straight region along the width direction of the winding body; the tail end of the first electrode sheet is closer to the first arc-shaped region along the width direction of the winding body, relative to the middle of the straight region along the width direction of the winding body.
8. The electrode assembly according to claim 7, characterized in that, The distance between the first end of the first electrode and the second arc-shaped area along the width direction of the winding body is 20mm~50mm, and the distance between the tail end of the first electrode and the first arc-shaped area along the width direction of the winding body is 20mm~50mm.
9. The electrode assembly according to claim 1, characterized in that, An insulating protective layer is provided at the first and last ends of the first electrode.
10. A secondary battery, characterized in that, It includes a housing, wherein the housing is provided with an electrode assembly as described in any one of claims 1 to 9.