Roller and rolling device

Abstract

The utility model provides a roller and a rolling device, which are used for rolling a plurality of pole pieces, the roller comprises a first end, a second end and a middle part, and the first end and the second end are used for mounting the roller. And the middle part comprises a plurality of rolling sections with different diameters and is used for rolling each pole piece. According to the utility model, the roller is designed to comprise a plurality of rolling sections with different diameters, each rolling section can correspond to each pole piece, and proper pressure can be accurately applied to each pole piece, so that the influence of deflection deformation of a long cylindrical roller (with a large ratio of length to diameter) is avoided, and the thickness uniformity of each pole piece can be improved. And even if the pole piece is abnormal in the coating process, the thickness uniformity can be improved by independently controlling the diameter of the corresponding rolling section.

Description

Technical Field

[0001] The utility model relates to the technical field of battery preparation, and specifically provides a roller and a rolling device. Background Art

[0002] In electrical devices (such as electric vehicles), the battery system is one of the key systems, and the power battery pack (hereinafter referred to as the battery pack) is the core component of the battery system. The power battery pack includes a box body and battery cells in the box body, etc. The battery cells include positive and negative pole pieces, isolation membranes and electrolytes.

[0003] In the preparation process of the pole piece, the active material is usually coated on the current collector first, and then rolled to obtain a pole piece with corresponding thickness and compaction density. However, in the prior art, the thickness of the pole piece is uneven, and the stress distribution of the pole piece is uneven, resulting in the risk of lithium deposition in the battery cell. Utility Model Content

[0004] In order to solve the problem of uneven thickness of pole pieces, the utility model provides a rolling roller for rolling a plurality of pole pieces, the rolling roller comprising a first end, a second end and a middle portion, the first end and the second end being used for installation; the middle portion being located between the first end and the second end; the middle portion comprising a plurality of rolling sections with different diameters for rolling each pole piece.

[0005] If a long cylindrical roller (with a large length-to-diameter ratio) is used to roll multiple pole pieces, the pole pieces at both ends of the long cylindrical roller will be thin and the pole pieces in the middle of the long cylindrical roller will be thick after rolling due to the deflection deformation of the long cylindrical roller, resulting in uneven thickness of the pole pieces. The utility model adopts a roller design that includes multiple rolling sections with different diameters. Each rolling section can correspond to each pole piece, and can accurately apply appropriate pressure to each pole piece, avoiding the influence of the deflection deformation of the long cylindrical roller, and improving the uniformity of thickness between each pole piece. Even if there is an abnormality in the pole piece coating process, the diameter of the corresponding rolling section can be individually controlled to improve the thickness uniformity.

[0006] In an optional technical solution of the utility model, transition sections are provided at both ends of the rolling section, and the diameter of the transition sections is smaller than the diameter of the rolling sections. The transition sections are used to roll the edges of each pole piece, and the rolling sections are used to roll the middle of each pole piece. In the design of the battery cell of a battery cell, a thin end area is generally provided, that is, the thickness of the active coating near the pole ear is designed to be thinner, that is, the coating on both sides of the width direction of the rolled pole piece is thinner. This solution provides transition sections with small diameters at both ends of the rolling section, and the transition sections correspond to the thin end areas of the rolled pole piece, and the rolling sections correspond to the middle areas of the rolled pole piece. This can improve the thickness distribution of the pole piece end, thereby preventing the safety risk of lithium plating in the battery cell caused by overvoltage at the pole piece end, and can also improve stress concentration at the pole piece end.

[0007] In an alternative technical solution of the present utility model, the width L1 of the transition section satisfies: 3 mm ≤ L1 ≤ 60 mm. The difference P between the minimum diameter of the transition section and the minimum diameter of the above-mentioned rolling section satisfies: 3 μm ≤ P ≤ 200 μm.

[0008] In an alternative technical solution of the present utility model, the transition section is arc-shaped or wedge-shaped.

[0009] In an alternative technical solution of the present utility model, the above-mentioned rolling mill roll further includes a connecting section located between two adjacent rolling sections. The diameter of the connecting section is smaller than that of the rolling section, and the transition section connects the rolling section and the connecting section.

[0010] In an alternative technical solution of the present utility model, the middle part includes a first rolling section, a second rolling section, and a third rolling section. The third rolling section is located between the first rolling section and the second rolling section; the diameter of the first rolling section is R1, the diameter of the second rolling section is R2, and the diameter of the third rolling section is R3. R1, R2, and R3 satisfy: R1 < R3, R2 < R3. If a long cylindrical roll is used to roll multiple pole pieces, due to the deflection deformation of the long cylindrical roll along its length direction, the pole pieces at both ends of the long cylindrical roll after rolling are thin, and the pole pieces in the middle of the long cylindrical roll are thick. In this solution, the diameters of the rolling sections at both ends of the entire rolling mill roll are designed to be smaller than the diameter of the rolling section in the middle, which can improve the problem of thin pole pieces at both ends and thick pole pieces in the middle, and make the thickness of the pole pieces at the edge and in the middle closer.

[0011] In an alternative technical solution of the present utility model, the middle part includes multiple third rolling sections, and the diameters of the respective third rolling sections are the same or different. The number of the third rolling sections can be determined according to the number of pole pieces to be rolled, and the diameters of the respective third rolling sections can be designed more precisely according to the coating thickness of each pole piece, thereby improving the thickness uniformity of each pole piece.

[0012] In an alternative technical solution of the present utility model, along the length direction of the above-mentioned rolling mill roll, the diameters of all parts of the rolling section are the same, or the diameters of the two ends of the rolling section are smaller than the diameter of the middle part of the rolling section.

[0013] The present utility model also provides a rolling device, which includes the above-mentioned rolling mill roll, a first driving member, and a second driving member; the first driving member is connected to the two rolling mill rolls and drives the two rolling mill rolls to approach or separate; the second driving member is connected to the first end and the second end and drives the two rolling mill rolls to rotate around the axis. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of the rolling device rolling a pole piece;

[0015] Figure 2is a schematic diagram of a roller including a plurality of rolling sections and a plurality of pole pieces;

[0016] Figure 3 It is a cross-sectional view of multiple pole pieces;

[0017] Figure 4 yes Figure 2 A partial enlarged view of

[0018] Reference numerals

[0019] Roller 100;

[0020] A first end 110, a second end 120, and a middle portion 130;

[0021] A first rolling section 131, a second rolling section 132, a third rolling section 133, a transition section 1311, and a connecting section 134;

[0022] Pole piece 200;

[0023] Thinned area 210 and first pole piece 220 . DETAILED DESCRIPTION

[0024] The following describes the optional implementations of the present invention with reference to the accompanying drawings. It should be understood by those skilled in the art that these implementations are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0025] In the description of the present invention, it should be understood that the terms "distance", "width", "thickness", "up", "down", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0026] In the description of the present invention, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present application, the battery cell may include a lithium-ion secondary battery cell, a lithium-ion primary battery cell, a lithium-sulfur battery cell, a sodium-lithium-ion battery cell, a sodium-ion battery cell or a magnesium-ion battery cell, etc., and the embodiments of the present application do not limit this. The battery cell may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this.

[0029] A battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. A battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. Both the positive and negative electrode sheets include a current collector and an active material layer, and the active material layer is coated on the surface of the current collector. The preparation of the positive and negative electrode sheets is usually to first apply the mixed active material coating to a large current collector, and to apply multiple coatings on the current collector at the same time, and then to roll the active material coating and the current collector through a rolling device so that the active material coating and the current collector are more tightly combined and the thickness is uniform. However, there is always a problem of uneven coating thickness of the electrode sheet.

[0030] like Figure 1 As shown, in order to solve the problem of uneven thickness of the pole piece, the present application provides a roller and a rolling device. The rolling device includes two rollers 100 and a first driving member (not shown) and a second driving member (not shown). The first driving member is connected to the two rollers to drive the two rollers to move closer or farther away; the second driving member is connected to both ends of each roller to drive the two rollers to rotate around the axis to roll the pole piece 200.

[0031] like Figure 2 As shown, the roller 100 of the utility model is used to roll a plurality of pole pieces 200, which are also generally called zebra pole pieces, that is, a plurality of coatings are applied on a foil at intervals. The roller 100 includes a first end 110, a second end 120 and a middle portion 130, and the first end 110 and the second end 120 are used for installation. The middle portion 130 is located between the first end 110 and the second end 120; the middle portion 130 includes a plurality of rolling sections with different diameters, which are used to roll each pole piece. Compared with the thin pole pieces at the two outermost parts and the thick pole piece in the middle after the long cylindrical rolling, the thickness of each pole piece prepared by the utility model using a plurality of rolling sections with different diameters is more uniform.

[0032] like Figure 2As shown, in an alternative embodiment of the present utility model, the middle part 130 includes a first rolling section 131, a second rolling section 132, and a third rolling section 133. The third rolling section 133 is located between the first rolling section 131 and the second rolling section 132. The diameter of the first rolling section 131 is R1, the diameter of the second rolling section 132 is R2, and the diameter of the third rolling section 133 is R3. R1, R2, and R3 satisfy: R1 < R3 and R2 < R3. If a long cylindrical roller is used to roll multiple electrode foils 200, due to the deflection deformation of the long cylindrical roller along its length direction, the electrode foils at both ends of the long cylindrical roller after rolling are thin, and the electrode foils in the middle of the long cylindrical roller are thick. In this solution, the diameters of the rolling sections at the outermost edges of the entire rolling roller (i.e., the first rolling section and the second rolling section) are designed to be smaller than the diameter of the rolling section in the middle (i.e., the third rolling section), which can improve the problem of thin electrode foils at both ends and thick electrode foils in the middle, making the thicknesses of the electrode foils at the edges and in the middle closer.

[0033] In an alternative embodiment of the present utility model, the middle part 130 includes a plurality of third rolling sections 133, and the diameters of the respective third rolling sections 133 are the same or different. The number of the third rolling sections 133 can be determined according to the number of electrode foils to be rolled, and the diameters of the respective third rolling sections 133 can be designed more precisely according to the coating thickness of each electrode foil, thereby improving the thickness uniformity of each electrode foil. Specifically, as Figure 2 shown, the middle part 130 includes two third rolling sections 133. Of course, it can also be three, four, etc. For example, in the case of including three third rolling sections 133, the diameter of the third rolling section in the middle among these three third rolling sections 133 can be larger than the diameters of the two third rolling sections on its both sides, or it can be the same as the diameter of one of the third rolling sections, specifically determined according to the thickness of the electrode foil coating to be rolled by each third rolling section.

[0034] In an alternative embodiment of the present utility model, along the length direction of the rolling roller 100, the diameters at various positions of the rolling section are the same, or the diameters of both ends of the rolling section are smaller than the diameter of the middle of the rolling section. For example, the first rolling section 131 and the second rolling section 132 are cylindrical with the same diameter at various positions, and the third rolling section 133 has a structure with smaller diameters at both ends and a larger diameter in the middle. It is also possible that the first rolling section 131, the second rolling section 132, and the third rolling section 133 are all cylindrical with the same diameter at various positions or have a structure with smaller diameters at both ends and a larger diameter in the middle.

[0035] In an alternative embodiment of the present utility model, as Figure 2 shown, transition sections are provided at both ends of each rolling section, and the diameter of the transition section is smaller than the diameter of the rolling section connected thereto. The transition section is used to roll the edges of each electrode foil, and the rolling section is used to roll the middle of each electrode foil.

[0036] As Figure 2 and Figure 3As shown, in the design of the battery cell of the battery cell, an end thinning area is generally provided, and a thinning area 210 is provided at both ends of the corresponding pole piece, that is, near the pole ear ( Figure 2 and Figure 3 The thickness of the active coating at the position of the blank space of the pole piece) is designed to be thinner, that is, the coating on both sides of the width direction of the rolled pole piece is thinner. In this scheme, a transition section with a small diameter is set at both ends of the rolling section. The transition section corresponds to the thin area at the end of the rolled pole piece, and the rolling section corresponds to the middle area of ​​the rolled pole piece. In this way, the thickness distribution of the pole piece end can be improved, thereby preventing the safety risk of lithium deposition in the battery cell caused by overvoltage at the end of the pole piece, and can also improve the stress concentration at the end of the pole piece (i.e., the thinning area 210). For example, transition sections 1311 are set at both ends of the first rolling section 131. The first rolling section 131 is used to roll the middle of the first pole piece 220, and the transition section 1311 is used to roll the edge of the first pole piece 220 (thinning area 210). A first pole piece 220 that is thick in the middle and thin on both sides can be obtained. After that, multiple pole pieces 200 are cut to obtain a single first pole piece 220. The first pole piece 220 can be rolled in or stacked to obtain a battery cell that is thick in the middle and thin at both ends, which can prevent the problem of lithium deposition.

[0037] In an optional embodiment of the present utility model, as Figure 2 and Figure 4 As shown, the width L1 of the transition section satisfies: 3mm≤L1≤60mm. The difference P between the minimum diameter of the transition section and the minimum diameter of the above-mentioned rolling section (ie P2-P1) satisfies: 3um≤P≤200um. The transition section can be arc-shaped or wedge-shaped.

[0038] In an optional embodiment of the present utility model, as Figure 2 As shown, the roller also includes a connecting section 134 located between two adjacent rolling sections, the diameter of the connecting section 134 is smaller than the rolling section, and the transition section connects the rolling section and the connecting section. By using a long roller with multiple rolling sections connected by the connecting section 134, multiple pole pieces 200 can be rolled at one time, and the thickness of each pole piece can be accurately controlled, which greatly improves the rolling efficiency and thickness uniformity of the pole pieces.

[0039] So far, the technical solution of the utility model has been described in conjunction with the optional implementation modes shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the utility model is obviously not limited to these specific implementation modes. Without departing from the principle of the utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the utility model.

Claims

1. A roller for rolling a plurality of pole pieces, characterized in that: include a first end and a second end, wherein the first end and the second end are used for mounting; a middle portion located between the first end and the second end; The middle portion includes a plurality of rolling sections with different diameters for rolling the pole pieces.

2. The roller according to claim 1, characterized in that Transition sections are provided at both ends of the rolling section, the diameter of the transition section is smaller than the diameter of the rolling section, the transition section is used to roll the edge of the pole piece, and the rolling section is used to roll the middle of the pole piece.

3. The roller according to claim 2, characterized in that The width L1 of the transition section satisfies: 3mm≤L1≤60mm.

4. The roller according to claim 2, characterized in that The difference P between the minimum diameter of the transition section and the minimum diameter of the rolling section satisfies: 3um≤P≤200um.

5. The roller according to claim 2, characterized in that The transition section is arc-shaped or wedge-shaped.

6. The roller according to claim 2, characterized in that The roller further comprises a connecting section between two adjacent rolling sections, the diameter of the connecting section is smaller than the rolling section, and the transition section connects the rolling section and the connecting section.

7. The roller according to claim 1, characterized in that The middle portion includes a first rolling section, a second rolling section and a third rolling section, wherein the third rolling section is located between the first rolling section and the second rolling section; The diameter of the first rolling section is R1, the diameter of the second rolling section is R2, and the diameter of the third rolling section is R3. R1, R2 and R3 satisfy: R1 <R3,R2<R3。 8. The roller according to claim 7, characterized in that The middle portion includes a plurality of third rolled segments, and the diameters of the plurality of third rolled segments are the same or different.

9. The roller according to claim 1, characterized in that Along the length direction of the rolling roller, the diameters of the rolling section are the same at all locations, or the diameters of the two ends of the rolling section are smaller than the diameter of the middle portion of the rolling section.

10. A rolling device, characterized in that: The rolling device comprises two rollers as claimed in any one of claims 1 to 9, and the rolling device further comprises a first driving member and a second driving member; The first driving member is connected to the two rollers and is used to drive the two rollers to move closer or farther away; the second driving member is connected to the first end and the second end and is used to drive the two rollers to rotate around an axis.

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