Separator and cell

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

[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 are mainly 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 winding core sandwiching a polar plate and a separator. The wound cell manufactured based on the conventional separator has a 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 above-described technical solution, in the present application, the separator is divided into regions with different widths, such that the widths of the regions located in the head portion and / or the tail portion of the separator are smaller than the width at the middle position of the separator. When the width of the head portion of the separator becomes narrower, the area of contact between the separator and the winding core becomes smaller, so that the frictional force between the surface of the separator and the winding core is reduced, avoiding the situation where a part of the separator is pulled out from the cell when the winding core is removed, and thus the problem of the separator coming off the core can be improved. When the width of the tail portion of the separator becomes narrower, that is, the width of the separator at the outer ring becomes narrower, 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.

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

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

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

[0009] By narrowing the width of the separator at the tail portion, that is, reducing the width of the separator at the outer ring, 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.

[0010] Embodiments of the present application further provide a cell. The cell includes two electrode plates with opposite polarities and a separator located between the two electrode plates. The cell is formed by winding the separator and the two electrode plates together. The separator is the separator described in any one of the above embodiments, and the first section of the separator is located at the starting end of the winding 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, for at least one of the two electrode plates, the projection in the plane where the separator is located is located 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, and H≧0.2mm.

[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, between the minimum width h2 of the first section and the width h3 of the electrode plate, 50%×h3≦h2≦h3+h1 is satisfied.

[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, between the minimum width h5 of the third section and the width h3 of the electrode plate, 50%×h3≦h5≦h3+h4 is satisfied.

[0020] In some embodiments, at least one of the two electrode plates includes an empty foil region and a tab disposed in the empty foil region, and 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 opposite 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 adhered.

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

Brief Description of the Drawings

[0023] To more clearly illustrate the embodiments of the present application, the drawings that need to be used in the following description of the embodiments or the prior art will be briefly introduced. Needless to say, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings based on these drawings without creative efforts.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0024] Hereinafter, the present application will be described in detail with reference 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 the 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] In addition, in the description of the present application, the terms "connection" and "connection" 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 through 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 meaning of the above terms in the present application based on the specific situation.

[0026] FIG. 1 and FIG. 2 are schematic structural diagrams of cells manufactured by a winding process. As shown in FIGS. 1 and 2, the wound cell 100 is formed by winding a positive electrode plate 101, a negative electrode plate 102, and a separator 103. Here, the separator 103 is installed between the positive electrode plate 101 and the negative electrode plate 102 to separate the positive electrode plate 101 and the negative electrode plate 102. Positive electrode tabs (not labeled) and negative electrode tabs (not labeled) are respectively installed on the positive electrode plate 101 and the negative electrode plate 102. During winding, the head portion 103a of the separator 103 is bent 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 completed, the winding core is drawn out from the side where the head portion 100a of the cell 100 is located. In a wound cell, the separator 103 is located in the innermost layer of the cell, and during winding, the winding core sandwiches the separator and winds the electrode plates together through the separator. Since the separator 103 has a portion that directly contacts the winding core, friction occurs between the surface coating layer of the separator in this portion and the winding core. After winding is completed, in the process of removing the winding core, since the winding core is easily pulled out together with the inner layer separator, a part of the separator is pulled out of the cell, causing a core deviation phenomenon. For example, a part of the separator is pulled out outside the head portion of the cell (the portion within the dotted line frame in FIG. 2). When the separator is pulled out, the mutual separation between the positive electrode plate and the negative electrode plate is affected, and the positive electrode plate and the negative electrode plate come into contact with each other, resulting in a short circuit. In serious cases, the wound cell may become invalid and the product yield may decrease. Also, for some wound cells finished with a separator, since the width of the separator is wide and the substrate is soft, the tail portion 103b of the separator is easily turned up during finishing, causing an increase in the thickness of the wound cell, which affects the energy density of the battery.

[0027] A wound cell is a cell manufactured by a winding process. The wound cell includes two current collectors with opposite polarities, and a separator is located between the two current collectors. During winding, the winding core is wound together with the stacked separator and current collectors to form a cell. For ease of explanation, one end of the separator located at the innermost layer of the cell is defined as the head portion of the separator, and the other end opposite to the head portion of the separator is defined as the tail portion of the separator. In some winding processes, the winding is finished with the separator, that is, the tail portion of the separator covers the outermost layer of the cell. The innermost layer of the cell is also the starting end of the cell winding.

[0028] The separator generally has a rectangular structure. The dimension of the long side of the rectangle is defined as the length of the separator, and the dimension of the short side of the rectangle is defined as the width of the separator. As shown in FIGS. 3 and 4, the embodiment of the present application provides a separator 1, and the separator 1 includes a first section 1-1, a second section 1-2, and a third section 1-3 that are sequentially connected along the length direction of the separator 1. The first section 1-1 is located on the head portion side of the separator, that is, during winding, the first section 1-1 is located at the starting end of the cell winding, that is, located in the inner layer of the cell. The third section 1-3 is located on the tail portion side of the separator, that is, during winding, 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, whereby the separator has a shape with narrower ends 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. Also, the width of the first section 1-1 gradually increases in the extending direction from one end far from the second section 1-2 of the first section 1-1 to one end close to the second section 1-2, that is, the first section 1-1 becomes narrower and 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 extending direction from one end far from the second section 1-2 of the third section 1-3 to one end close to the second section 1-2, that is, the third section 1-3 becomes narrower and narrower in the direction away from the second section 1-2. To ensure separating the positive electrode plate and the negative electrode plate, the width at the narrowest position of the separator 1, that is, the minimum width of the separator 1, is larger than the width of the electrode plate (positive electrode plate and / or negative electrode plate). That is, when the electrode plate and the separator are stacked flatly, the projection of the electrode plate on the plane where the separator is located is located within the separator (as shown in FIG. 4). Thereby, when the separator and the electrode plate are laminated or wound, the separator can always completely cover the electrode plate, and it is possible to avoid the electrode plates with opposite polarities separated by the separator from contacting each other.

[0030] In this application, by dividing the separator into regions with different widths, the widths of the regions located at the head part (the first section) and / or the regions located at the tail part (the third region) of the separator are made smaller than the width at the middle position of the separator. By narrowing the width at the head part 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 reduced, and when the winding core is removed, it is avoided that part of the separator is pulled out from the cell, thereby improving the problem of the separator coming off the core. In some embodiments, the width of the region of the tail part of the separator is also smaller than the widths at other positions of the separator, whereby the degree of the tail part 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.

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

[0032] In some embodiments, the cell includes a first electrode plate and a second electrode plate with opposite polarities, and the separator includes a first separator and a second separator respectively located on both sides of the first electrode plate facing each other. The first separator and the second separator cover the first electrode plate. As shown in FIG. 5, as one embodiment of the present application, before winding the first electrode plate, the second electrode plate, the first separator, and the second separator, the first electrode plate and the first separator and the second separator located on both side surfaces thereof are compounded and adhered, and then the first electrode plate with the separator compounded thereon is stacked and wound with the second electrode plate. In some embodiments, the first separator and the second separator respectively located on both sides of the first electrode plate facing each other have the same length, and by adopting two separators of the same length, the occurrence of displacement during winding can be avoided.

[0033] As shown in FIG. 4, the separator 1 is longer and wider than the electrode plate Q. The separator 1 exceeds the electrode plate Q in both the length direction and the width direction. 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 located on the same side is H, and H≥0.2 mm. That is, in the width direction, the dimensions by which both sides of the separator 1 in the second section 1-2 exceed the electrode plate Q respectively are H, that is, both sides of the separator 1 in the second section 1-2 exceed the electrode plate by more than 0.2 mm respectively.

[0034] The length w1 of the first section 1-1 of the 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 current collector plate Q located on the same side is h1, which satisfies 3%×H≦h1≦97%×H. That is, on one side in the width direction, the first section 1-1 of the separator 1 extends at least beyond the current collector plate by h1. When the width of the first section 1-1 gradually decreases along the direction away from the second section 1-2, h1 is not a fixed value but a numerical range. When the first section 1-1 is a rectangular area with a constant width, h1 is a fixed value. The minimum width h2 of the first section 1-1 and the width h3 of the current collector plate Q further satisfy 50%×h3≦h2≦h3+h1, where h3 is the width of the current collector plate.

[0035] The length w2 of the third section 1-3 of the 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 current collector plate Q located on the same side is h4, which satisfies 3%×H≦h4≦97%×H. That is, on both sides of the separator 1 in the third section 1-3 in the width direction, the dimensions exceeding the current collector plate Q are at least h4 respectively. Similarly, when the width of the third section 1-3 gradually decreases along the direction away from the second section 1-2, h4 is not a fixed value but a numerical range. When the third section 1-3 is a rectangular area with an unchanged width, h4 is a fixed value. The minimum width value h5 of the third section 1-3 and the width h3 of the current collector plate Q further satisfy 50%×h3≦h5≦h3+h4.

[0036] As shown in FIG. 4, there is an empty foil area N on the current collector plate Q where no active material is coated, and the empty foil area N is used for welding the tab M. The tab M is installed in the empty foil area N of the current collector plate Q and extends along the width direction of the separator 1 beyond the current collector plate Q. After the tab M is installed on the current collector plate Q, the projection of the portion of the tab M located on the current collector plate Q (the portion of the tab that does not exceed the current collector plate) on 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 area N of the current collector plate Q on the plane where the separator 1 is located is located within the first section 1-1 of the separator 1.

[0037] Based on the above description of the disclosed embodiments, those skilled in the art can implement or use this application. Various modifications to these embodiments will be apparent 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. Therefore, this application is not limited to the embodiments shown in this specification, but conforms to the broadest scope consistent with the principles and novel features disclosed in this specification.

Claims

1. A separator, wherein 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, characterized in that it is a separator.

2. The width of the first section gradually increases in the extending direction from one end of the first section away from the second section to one end of the first section close to the second section, characterized in that it is the separator according to Claim 1.

3. The width of the third section gradually increases in the extending direction from one end of the third section away from the second section to one end of the third section close to the second section, characterized in that it is the separator according to Claim 1 or 2.

4. A cell including two electrode plates with opposite polarities and a separator located between the two electrode plates, wherein the separator and the two electrode plates are wound together, wherein the separator is the separator according to any one of Claims 1 to 3, and the first section of the separator is located at the winding start end of the cell, characterized in that it is a cell.

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

6. The length w2 of the third section of the separator satisfies 10%×W≤w2≤3×W, characterized in that it is the cell according to Claim 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, characterized in that it is the cell according to Claim 4.

8. At least one of the two electrode plates has a projection in the plane where the separator is located and is located within the separator, characterized in that it is the cell according to any one of Claims 4 to 7.

9. 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, and H≥0.2 mm, characterized in that it is the cell according to any one of Claims 4 to 8.

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, characterized in that it is the cell according to Claim 9.

11. Between the minimum width h2 of the first section and the width h3 of the electrode plate, 50%×h3 ≤ h2 ≤ h3 + h1 is satisfied. The cell according to claim 10, characterized in that.

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 any one of claims 9 to 11, characterized in that.

13. Between the minimum width h5 of the third section and the width h3 of the electrode plate, 50%×h3 ≤ h5 ≤ h3 + h4 is satisfied. The cell according to claim 12, characterized in that.

14. At least one of the two electrode plates includes an empty foil region and a tab installed in the empty foil region. 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. The cell according to any one of claims 4 to 13, characterized in that.

15. 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 opposite sides of the first electrode plate. The first separator and the second separator cover the first electrode plate. The first separator, the first electrode plate, and the second separator are adhered. The cell according to any one of claims 4 to 14, characterized in that.

16. The first separator and the second separator have the same length. The cell according to claim 15, characterized in that.

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