Separators and cells

Abstract

This application provides a separator and a cell, and the separator is used, together with the electrode plates, to manufacture a cell by winding. The separator includes a first section, a second section, and a third section sequentially arranged along the length direction of the separator. The width of the first section is smaller than the width of the second section, and / or the width of the third section is smaller than the width of the second section. This application divides the separator into regions with different widths such that the width of the region located at the head portion and / or the tail portion of the separator is smaller than the width at the middle position of the separator. By narrowing the width at the head portion of the separator, the contact area between the separator and the winding core is reduced, the frictional force between the separator surface and the winding core is decreased, and the problem of the separator coming off the core is improved. By narrowing the width at the tail portion of the separator, the degree of the tail portion of the separator breaking off during the finishing of the separator winding can be reduced, and the problem of the separator curling during the finishing of the cell winding can be improved. By improving the problem of the separator coming off the core and / or the problem of the separator curling during the finishing of the cell winding, the quality of the battery can be improved.

Description

Technical Field

[0005] ,

[0001] This application belongs to the field of battery technology, and specifically relates to separators and cells.

Background Art

[0002] A secondary battery usually includes a cell and a case. Cells mainly include laminated cells and wound cells by different manufacturing processes. A wound cell is a flat cell manufactured by adopting a winding process and winding with a core sandwiched between electrode plates and a separator. The wound cell manufactured based on the conventional separator has the problem of poor cell quality.

Summary of the Invention

[0003] The object of this application is to provide a separator and a cell that can improve battery quality.

[0004] An embodiment of this application provides a separator, which includes a first section, a second section, and a third section sequentially arranged along the length direction of the separator. The width of the first section is smaller than the width of the second section, and / or the width of the third section is smaller than the width of the second section.

[0005] According to the technical solution described above, this application divides the separator into regions of different widths, such that the width of the regions located at the head and / or tail of the separator is smaller than the width of the intermediate position of the separator. When the width of the head portion of the separator is narrowed, the contact area between the separator and the winding core is reduced, thereby reducing the frictional force between the separator surface and the winding core. This prevents some of the separator from being pulled out of the cell when the winding core is removed, thus improving the problem of the separator coming off the core. When the width of the tail portion of the separator is narrowed, that is, when the width of the separator on the outer ring is narrowed, the degree to which the tail portion of the separator swings out during the finishing of the separator winding is reduced, improving the problem of the separator peeling during the finishing of the cell winding. By improving the problem of the core coming off and / or the problem of the separator peeling during the finishing of the cell winding, the quality of the battery can be improved.

[0006] In some embodiments, the width of the first section gradually increases in the direction of extension from one end of the first section away from the second section to the other end closer to the second section.

[0007] By gradually narrowing the width of the first section in the direction away from the second section, it is possible to ensure that the electrode plates are separated from each other, and by reducing the contact area between the separator and the winding core, the frictional force between the separator surface and the winding core can be reduced, thereby improving the problem of core derailment.

[0008] In some embodiments, the width of the third section gradually increases in the direction of extension from one end of the third section away from the second section to the other end closer to the second section.

[0009] By narrowing the width of the separator tail, that is, by reducing the width of the separator on the outer ring, the degree to which the separator tail is flipped over during the finishing of the separator winding can be reduced, thereby improving the problem of the separator curling up during the finishing of the cell winding.

[0010] Embodiments of the present application further provide a cell comprising two plates having opposite polarities and a separator located between the two plates, wherein the cell is formed by winding the separator and the two plates in overlapping manner, the separator being the separator described in any one embodiment above, and the first section of the separator being located at the winding start end of the cell.

[0011] In some embodiments, the length w1 of the first section satisfies 10% × W ≤ w1 ≤ 3 × W, where W is the width of the cell.

[0012] In some embodiments, the length w2 of the third section of the separator satisfies 10% × W ≤ w2 ≤ 3 × W.

[0013] In some embodiments, the length w2 of the third section of the separator satisfies 10% × W ≤ w2 ≤ 3 × W, where W is the width of the cell.

[0014] In some embodiments, at least one of the two plates has a projection of itself in the plane on which the separator is located that is positioned within the separator.

[0015] In some embodiments, on one side in the width direction of the separator, the distance between the outer edge of the second section of the separator and the outer edge of at least one of the two electrode plates is H, where H ≥ 0.2 mm.

[0016] In some embodiments, on one side in the width direction of the separator, the distance h1 between the outer edge of the first section and the outer edge of the electrode plate satisfies 3% × H ≤ h1 ≤ 97% × H.

[0017] In some embodiments, the interval between the minimum width h2 of the first section and the width h3 of the electrode plate satisfies 50% × h3 ≤ h2 ≤ h3 + h1.

[0018] In some embodiments, on one side in the width direction of the separator, the distance h4 between the outer edge of the third section of the separator and the outer edge of the electrode plate satisfies 3% × H ≤ h4 ≤ 97% × H.

[0019] In some embodiments, the interval between the minimum width h5 of the third section and the width h3 of the electrode plate satisfies 50% × h3 ≤ h5 ≤ h3 + h4.

[0020] In some embodiments, at least one of the two electrode plates includes an empty foil region and a tab placed in the empty foil region, wherein the projection of the portion of the tab located on the electrode plate in the plane where the separator is located is located within the first section.

[0021] In some embodiments, the two electrode plates include a first electrode plate and a second electrode plate, the separator includes a first separator and a second separator located on two opposing sides of the first electrode plate, the first separator and the second separator cover the first electrode plate, and the first separator, the first electrode plate and the second separator are bonded together.

[0022] In some embodiments, the first separator and the second separator have the same length. [Brief explanation of the drawing]

[0023] To more clearly illustrate the embodiments of this application, the following drawings are briefly presented as they may be used in the description of the embodiments or the prior art. Needless to say, the drawings in the following description are only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these without any creative effort. [Figure 1] This is a schematic diagram of the structure of a wound cell according to one embodiment of the present application. [Figure 2] This is a schematic diagram illustrating a core delamination of a wound cell according to one embodiment of the present application. [Figure 3] This is a schematic diagram of the structure of a separator according to one embodiment of this application. [Figure 4] It is a laminated schematic diagram of a separator and an electrode plate according to one embodiment of the present application. [Figure 5] It is a laminated schematic diagram of an electrode plate and a separator according to another embodiment of the present application. Hereinafter, specific embodiments of the present application will be described in more detail while referring to the drawings.

Embodiments for Carrying out the Invention

[0024] Hereinafter, the present application will be described in detail while referring to the drawings. When describing the embodiments of the present application in detail, for ease of explanation, the drawings showing the component structures are not partially enlarged in normal proportion. Also, the above schematic diagrams are merely examples and do not limit the protection scope of the present application. Note that the drawings are shown in a simplified manner and all use non-precise proportions, and are merely for easily and clearly explaining the embodiments of the present application. In addition, in the description of the present application, terms such as "first", "second", etc. are merely for distinguishing explanations and should not be understood as indicating or implying relative importance or implicitly indicating the number of such components. The orientation or positional relationship indicated by terms such as "positive", "negative", "bottom", "top", "bottom", etc. is shown based on the drawings and is merely for easily and clearly explaining the present application, and does not indicate or imply that such devices or elements must have a specific orientation and be configured and operated in a specific orientation, so it should not be understood as a limitation to the present application.

[0025] Note that in the description of the present application, the terms "connected" and "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection. It may be a direct connection or an indirect connection via an intermediate medium, or a communication inside two elements. It may be a wireless connection or a wired connection. Those skilled in the art may understand the specific meanings of the above terms in the present application based on specific situations.

[0026] Figures 1 and 2 are schematic diagrams of the structure of a cell manufactured by a winding process. As shown in Figures 1 and 2, the wound cell 100 consists of a positive electrode plate 101, a negative electrode plate 102, and a separator 103 wound together. The separator 103 is placed between the positive electrode plate 101 and the negative electrode plate 102, separating them. The positive electrode plate 101 and the negative electrode plate 102 are fitted with positive electrode tabs (unsigned) and negative electrode tabs (unsigned), respectively. During winding, the head portion 103a of the separator 103 is folded and overlapped, and is located in the innermost layer of the cell 100. The cell 100 has a head portion 100a and a tail portion 100b. After winding is complete, the core is pulled out from the side where the head portion 100a of the cell 100 is located. In a wound cell, the separator Ta The core is located in the innermost layer of the cell, and during winding, the core winds together with the electrode plates via the separator, with the separator in between. Ta Because the separator has a portion that is in direct contact with the core, friction occurs between the surface coating layer of the separator in this portion and the core. After winding is complete, during the process of removing the core, the core is easily pulled out together with the inner layer separator, causing some of the separator to be pulled out of the cell, resulting in a core derailment phenomenon. For example, part of the separator is pulled out of the head portion of the cell (the portion within the dotted line frame in Figure 2). When the separator is pulled out, the mutual separation between the positive and negative electrodes is affected, causing the positive and negative electrodes to come into contact with each other and a short circuit to occur. In serious cases, this can render the wound cell useless and reduce the product yield. Also, for some wound cells that are finished with a separator, the separator is wide and the base material is soft, so the tail of the separator during finishing... Department The material is prone to peeling, which increases the thickness of the wound cell and affects the battery's energy density.

[0027] A wound cell is a cell manufactured by a winding process, and it contains two plates with opposite polarities, with a separator located between the two plates. During winding, the core is wound together with the stacked separator and plates to form the cell. For ease of explanation, one end of the separator located in the innermost layer of the cell is defined as the head of the separator, and the other end opposite the head of the separator is defined as the tail of the separator. In some winding processes, the separator is used as a finish, meaning the tail of the separator covers the outermost layer of the cell. The innermost layer of the cell is also the starting point of the cell winding.

[0028] A separator typically has a rectangular structure, with the length of the rectangle defined as the length of the separator and the width of the rectangle defined as the width of the separator. As shown in Figures 3 and 4, embodiments of the present application provide a separator 1 which includes a first section 1-1, a second section 1-2, and a third section 1-3 that are sequentially connected along the length of the separator 1. The first section 1-1 is located on the head side of the separator, i.e., when wound, the first section 1-1 is located at the winding start end of the cell, i.e., in the inner layer of the cell. The third section 1-3 is located on the tail side of the separator, i.e., when wound, the third section 1-3 is located in the outer layer of the cell. The width of the first section 1-1 is smaller than the width of the second section 1-2, and / or the width of the third section 1-3 is smaller than the width of the second section 1-2, so that the separator has a shape where the ends are narrower than the middle.

[0029] In some embodiments, the widths of the first section 1-1 and the third section 1-3 are both smaller than the width of the second section 1-2. Furthermore, the width of the first section 1-1 gradually increases in the direction of extension from one end of the first section 1-1 away from the second section 1-2 to the one end closer to the second section 1-2, i.e., the first section 1-1 becomes increasingly narrower along the direction away from the second section 1-2, and / or, the width of the third section 1-3 gradually increases in the direction of extension from one end of the third section 1-3 away from the second section 1-2 to the one end closer to the second section 1-2, i.e., the third section 1-3 becomes increasingly narrower in the direction away from the second section 1-2. To ensure separation of the positive and negative plates, the width of the separator 1 at its narrowest point, i.e., the minimum width of the separator 1, is greater than the width of the plates (positive and / or negative plates). In other words, when the electrode plates and separators are stacked flat, the projection of the electrode plate onto the plane where the separator is located is situated within the separator (as shown in Figure 4). This ensures that when the separator and electrode plates are stacked or wound, the separator can always completely cover the electrode plate, preventing contact between electrode plates with opposite polarities that are separated by the separator.

[0030] This application divides the separator into regions of different widths, thereby making the width of the region located at the head of the separator (first section) and / or the region located at the tail of the separator (third region) smaller than the width of the intermediate position of the separator. By narrowing the width at the head of the separator, the contact area between the separator and the core is reduced, thereby reducing the frictional force between the separator surface and the core, preventing some of the separator from being pulled out of the cell when the core is removed, and improving the problem of the separator coming off the core. In some embodiments, the width of the tail region of the separator is also smaller than the width of other parts of the separator, thereby reducing the degree to which the tail of the separator swings out during the finishing of the separator winding, and improving the problem of the separator curling during the finishing of the cell winding.

[0031] Embodiments of this application further provide a cell comprising two plates with opposite polarities and a separator located between the two plates, wherein the separator and the two plates are wound together to form the cell. The separator may be any of the separators described in any one of the embodiments described above, the first section of the separator located at the starting end of the cell winding.

[0032] In some embodiments, the cell includes a first electrode plate and a second electrode plate with opposite polarity, and the separator includes a first separator and a second separator located on opposite sides of the first electrode plate, respectively, with the first and second separators covering the first electrode plate. As shown in Figure 5, in one embodiment of the present application, the first electrode plate and the first and second separators located on both sides of its surface may be bonded together before winding the first electrode plate, the second electrode plate and the first and second separators, and then the first electrode plate with the bonded separators may be stacked with the second electrode plate and wound. In some embodiments, the first and second separators located on opposite sides of the first electrode plate are of the same length, and by using two separators of the same length, misalignment during winding can be avoided.

[0033] As shown in Figure 4, the separator 1 is longer and wider than the electrode plate Q, and the separator 1 exceeds the electrode plate Q in both the length and width directions. In some embodiments, in the width direction of the separator, the distance between the outer edge of the second section 1-2 of the separator 1 and the outer edge of the electrode plate Q on the same side is H, where H ≥ 0.2 mm. That is, in the width direction, the dimension that both sides of the separator 1 in the second section 1-2 extend beyond the electrode plate Q is H, meaning that both sides of the separator 1 in the second section 1-2 extend 0.2 mm beyond the electrode plate.

[0034] The length w1 of the first section 1-1 of separator 1 satisfies 10% × W ≤ w1 ≤ 3 × W, where W is the width of the cell. In the width direction of the separator, the distance between the outer edge of the first section 1-1 and the outer edge of the electrode plate Q on the same side is h1, satisfying 3% × H ≤ h1 ≤ 97% × H, that is, on one side in the width direction, the first section 1-1 of separator 1 extends at least h1 beyond the electrode plate. If the width of the first section 1-1 gradually decreases along the direction away from the second section 1-2, h1 is a numerical range, not a constant value. If the first section 1-1 is a rectangular region with an invariant width, h1 is a constant value. Between the minimum width h2 of the first section 1-1 and the width h3 of the electrode plate Q, the distance further satisfies 50% × h3 ≤ h2 ≤ h3 + h1, where h3 is the width of the electrode plate.

[0035] The length w2 of the third section 1-3 of separator 1 satisfies 10% × W ≤ w2 ≤ 3 × W. In the width direction, the distance between the outer edge of the third section 1-3 and the outer edge of the electrode plate Q on the same side is h4, satisfying 3% × H ≤ h4 ≤ 97% × H. That is, in the width direction, both sides of separator 1 in the third section 1-3 each exceed the electrode plate Q by at least h4. Similarly, if the width of the third section 1-3 gradually decreases along the direction away from the second section 1-2, h4 is a numerical range, not a constant value. If the third section 1-3 is a rectangular region with no change in width, h4 is a constant value. Between the minimum width value h5 of the third section 1-3 and the width h3 of the electrode plate Q, the further value 50% × h3 ≤ h5 ≤ h3 + h4 is satisfied.

[0036] As shown in Figure 4, the electrode plate Q has an empty foil region N where no active material is coated, and this empty foil region N is used for welding the tab M. The tab M is placed in the empty foil region N of the electrode plate Q and extends along the width direction of the separator 1, extending beyond the electrode plate Q. After the tab M is placed in the electrode plate Q, the projection of the portion of the tab M located on the electrode plate Q (the portion of the tab that does not extend beyond the electrode plate) onto the plane where the separator 1 is located is located within the first section 1-1 of the separator 1. That is, the projection of the empty foil region N of the electrode plate Q onto the plane where the separator 1 is located is located within the first section 1-1 of the separator 1.

[0037] The above description of the disclosed embodiments will enable those skilled in the art to implement or use the present application. Various modifications of these embodiments will be obvious to those skilled in the art, and the general principles defined in this specification may be implemented in other embodiments without departing from the spirit or scope of this application. Thus, this application is not limited to the embodiments shown in this specification, but fits to the broadest extent that is consistent with the principles and novel features disclosed in this specification.

Claims

1. A separator used in a wound cell, The separator consists of a first section, a second section, and a third section that are sequentially installed along the length of the separator, wherein the width of the first section is smaller than the width of the second section, and / or the width of the third section is smaller than the width of the second section. In a wound cell formed by winding the separator and electrode plates together, the first section is located on the head side of the separator, the third section is located on the tail side of the separator, the first section is located at the winding start end of the wound cell, and the third section is located on the outer layer of the wound cell. A separator characterized by the following features.

2. The width of the first section gradually increases in the direction of extension from one end of the first section away from the second section to the one end closer to the second section. The separator according to feature 1.

3. The width of the third section gradually increases in the direction of extension from one end of the third section away from the second section to the one end closer to the second section. The separator according to feature 1.

4. A cell comprising two plates with opposite polarities and a separator located between the two plates, wherein the separator and the two plates are wound together in a stacked manner, The separator is the separator according to any one of claims 1 to 3, wherein the first section of the separator is located at the winding start end of the cell, and the third section of the separator is located in the outer layer of the wound cell. A cell characterized by the following features.

5. The length w1 of the first section satisfies 10% × W ≤ w1 ≤ 3 × W, where W is the width of the cell. The cell according to feature 4.

6. The length w2 of the third section of the separator satisfies 10% × W ≤ w2 ≤ 3 × W. The cell according to feature 5.

7. The length w2 of the third section of the separator is 10% × W ≤ w2 ≤ 3 × W, where W is the width of the cell. The cell according to feature 4.

8. At least one of the two plates has a projection of itself in the plane on which the separator is located that is positioned within the separator. The cell according to feature 4.

9. On one side of the separator in the width direction, the distance between the outer edge of the second section of the separator and the outer edge of at least one of the two electrode plates is H, and H ≥ 0.2 mm. The cell according to feature 4.

10. On one side in the width direction of the separator, the distance h1 between the outer edge of the first section and the outer edge of the electrode plate satisfies 3% × H ≤ h1 ≤ 97% × H. The cell according to feature 9.

11. The distance between the minimum width h2 of the first section and the width h3 of the electrode plate satisfies 50% × h3 ≤ h2 ≤ h3 + h1. The cell according to feature 10.

12. On one side in the width direction of the separator, the distance h4 between the outer edge of the third section of the separator and the outer edge of the electrode plate satisfies 3% × H ≤ h4 ≤ 97% × H. The cell according to feature 9.

13. The distance between the minimum width h5 of the third section and the width h3 of the electrode plate satisfies 50% × h3 ≤ h5 ≤ h3 + h4. The cell according to feature 12.

14. At least one of the two electrode plates includes an empty foil region and a tab installed in the empty foil region. The tab, the portion located on the electrode plate, has a projection on the plane where the separator is located that is located within the first section. The cell according to feature 4.

15. The two plates mentioned above include a first plate and a second plate. The separator includes a first separator and a second separator located on two opposing sides of the first electrode plate, wherein the first separator and the second separator have the same length. The first separator and the second separator cover the first electrode plate. The first separator, the first electrode plate, and the second separator are bonded together. The cell according to feature 4.

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