Roll Press Equipment

Abstract

To provide a technology that suppresses breakage of an uncoated portions of an electrode plate.SOLUTION: A roll press device that rolls an electrode plate in which a coated portion coated with an active material and an uncoated portion where the active material is not coated are lined up in the width direction includes a first rolling roll that rolls at least the coated portion of the electrode plate, and a second rolling roll that rolls only the uncoated portion of the electrode plate. The second rolling roll includes a roll body made of an elastic material, and a plurality of fibers contained in the roll body, and the plurality of fibers are oriented in the axial direction of the second rolling roll.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a roll press apparatus. [Background technology]

[0002] An electrode plate having an active material coated on the surface of a metal foil is used as an electrode plate for a secondary battery such as a lithium ion battery. Such an electrode plate is produced by applying an active material to the surface of a metal foil and then rolling the applied material using a roll press device.

[0003] In the electrode plate, the coated portion coated with the active material and the uncoated portion not coated with the active material are arranged side by side in the width direction. When such an electrode plate is rolled using a roll press device, the rolling roller comes into contact with only the active material, and only the coated portion of the electrode plate is rolled. This causes a difference in elongation between the coated portion and the uncoated portion of the electrode plate, and wrinkles are generated in the uncoated portion. Such wrinkles can cause damage to the electrode plate when the electrode plate is wound up.

[0004] Patent Document 1 discloses a technique for reducing the difference in elongation between the coated and uncoated parts of an electrode plate by rolling the uncoated parts of the electrode plate using a rolling roller that rolls only the uncoated parts of the electrode plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-102172 A Summary of the Invention [Problem to be solved by the invention]

[0006] When only the uncoated portion of an electrode plate is rolled using a rolling roller, if the uncoated portion elongates significantly in the width direction, there is a risk that the uncoated portion will break. This specification provides a technique for suppressing breakage of the uncoated portion of the electrode plate. [Means for solving the problem]

[0007] The technology disclosed in this specification is applied to a roll press device that rolls an electrode plate in which a coated portion coated with an active material and an uncoated portion not coated with the active material are arranged in the width direction. This roll press device may include a first rolling roll that rolls at least the coated portion of the electrode plate, and a second rolling roll that rolls only the uncoated portion of the electrode plate. The second rolling roll may include a roll body portion made of an elastic material and a plurality of fibers contained in the roll body portion. The plurality of fibers are oriented in the axial direction of the second rolling roll. Therefore, the roll body portion of the second rolling roll is prevented from elastically deforming in the axial direction during pressing. Since the elastic deformation of the roll body portion in the axial direction is prevented, when the uncoated portion of the electrode plate is rolled, the elongation in the width direction of the uncoated portion of the electrode plate is prevented. As a result, the breakage of the uncoated portion of the electrode plate is prevented.

[0008] In the above roll press device, the roll body of the second rolling roll may have a surface layer that contacts the uncoated portion of the electrode plate and an internal layer located below the surface layer. The plurality of fibers may be included in the internal layer and may not be included in the surface layer. Since the plurality of fibers are not included in the surface layer, the plurality of fibers are not exposed on the outermost surface of the roll body. Therefore, when the uncoated portion of the electrode plate is rolled using the second rolling roll, damage to the uncoated portion of the electrode plate is suppressed. The surface layer and the internal layer may be made of the same type of elastic material. The thickness of the surface layer may be smaller than the thickness of the internal layer. [Brief description of the drawings]

[0009] [Figure 1] 1 shows an outline of the configuration of a roll press device. [Diagram 2] 1 shows an outline of how the roll press device rolls the electrode plate. [Diagram 3] FIG. 2 is a front view of a second roll for rolling only the uncoated portion of the electrode plate. [Figure 4] 4 is a cross-sectional view of a second rolling roll that rolls only the uncoated portion of the electrode plate, the cross-sectional view corresponding to line IV-IV in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As shown in FIG. 1, an unwinder 2 on which an electrode plate 12 before pressing is wound into a coil shape is provided on the entrance side of the roll press device 1, and a winder 4 on which an electrode plate 12 after pressing is wound into a coil shape is provided on the exit side of the roll press device 1. The arrow in the figure indicates the transport direction of the electrode plate 12. The roll press device 1 is provided between the unwinder 2 and the winder 4, and includes a first rolling roll 22 and a plurality of second rolling rolls 24. In this example, the second rolling rolls 24 are provided at positions upstream and downstream of the position of the first rolling roll 22 in the transport direction of the electrode plate 12. Instead of this example, the second rolling roll 24 may be provided only at one of the positions upstream and downstream of the position of the first rolling roll 22 in the transport direction of the electrode plate 12.

[0011] As shown in FIG. 2, the electrode plate 12 has a long metal foil 14 and an active material 16 coated on the surface of the metal foil 14. The active material 16 is coated on both the upper and lower surfaces of the metal foil 14. The active material 16 is continuously coated along the longitudinal direction of the metal foil 14, and is not coated on both ends of the metal foil 14 in the width direction. In the electrode plate 12, the area coated with the active material 16 is called the coated portion 12A, and the area not coated with the active material 16 is called the uncoated portion 12B. Thus, in the electrode plate 12, the coated portion 12A and the uncoated portion 12B are arranged side by side in the width direction. The uncoated portion 12B of the electrode plate 12 is used as a portion to which a terminal is connected. The electrode plate 12 in this example is formed by coating the surface of the metal foil 14 with a strip of the active material 16. Alternatively, the electrode plate 12 may have a plurality of stripes of active material 16 applied to the surface of the metal foil 14 .

[0012] As shown in FIG. 1 and FIG. 2, the first rolling roll 22 has a pair of press rolls 22U, 22L, and is configured to roll the electrode plate 12 passing between the upper press roll 22U and the lower press roll 22L. The first rolling roll 22 is disposed so that its axial length is greater than the widthwise length of the electrode plate 12 and faces the entire width of the electrode plate 12. The first rolling roll 22 is configured to roll the electrode plate 12 so that the total thickness of the metal foil 14 and the active material 16, i.e., the thickness of the electrode plate 12, becomes a predetermined thickness. When the first rolling roll 22 rolls the electrode plate 12, the first rolling roll 22 comes into contact with only the active material 16. Therefore, the first rolling roll 22 rolls only the coated portion 12A of the electrode plate 12.

[0013] 1 and 2, the second rolling rolls 24 are disposed corresponding to the uncoated portions 12B at both ends in the width direction of the electrode plate 12, and have a pair of press rolls 24U, 24L. The axial length of the second rolling rolls 24 is equal to or smaller than the width direction length of the corresponding uncoated portions 12B. The second rolling rolls 24 are configured to roll only the uncoated portions 12B of the electrode plate 12 that pass between the upper press roll 24U and the lower press roll 24L.

[0014] As explained in the background art, when electrode plate 12 is rolled only with first reduction roll 22, wrinkles occur in uncoated portion 12B of electrode plate 12 due to the difference in elongation between coated portion 12A and uncoated portion 12B of electrode plate 12. In roll press device 1, second reduction roll 24 rolls only uncoated portion 12B of electrode plate 12, thereby reducing the difference in elongation between coated portion 12A and uncoated portion 12B of electrode plate 12, and thus wrinkles in uncoated portion 12B of electrode plate 12 are suppressed.

[0015] As shown in Figures 3 and 4, the second rolling roll 24 has a roll body 32, a roll shaft 34, and a rotating shaft rod 36. The roll body 32 is formed of an elastic material and has a cylindrical shape. The roll body 32 is fixed to the roll shaft 34 so as to cover the periphery of the roll shaft 34. The roll shaft 34 is formed of a metal material and has a cylindrical shape. The rotating shaft rod 36 is inserted into the roll shaft 34.

[0016] A plurality of fibers 38 are embedded in the roll body 32. The plurality of fibers 38 may be, but are not limited to, inorganic fibers such as glass fibers or metal fibers, or organic fibers such as polyester. The plurality of fibers 38 are oriented in the axial direction of the second rolling roll 24. Here, the longitudinal direction of each of the plurality of fibers 38 is not necessarily parallel to the axial direction of the second rolling roll 24. A set of the longitudinal directions of each of the plurality of fibers 38 is normally distributed with the axial direction of the second rolling roll 24 as the approximate center. Therefore, "the plurality of fibers 38 are oriented in the axial direction of the second rolling roll 24" means that the average value of the direction of each line segment of the plurality of fibers 38 projected onto an arbitrary plane parallel to the axial direction of the second rolling roll 24 is within ±10° of the axial direction of the second rolling roll 24.

[0017] As shown in FIG. 4, the roll body 32 has a surface layer 32A and an internal layer 32B. The surface layer 32A defines a layer including the outermost surface of the roll body 32, and is a portion that contacts the uncoated portion 12B of the electrode plate 12. The internal layer 32B is a layer located below the surface layer 32A. In this example, the surface layer 32A and the internal layer 32B are made of the same type of elastic material and are an integrated single layer. Alternatively, the surface layer 32A and the internal layer 32B may be made of two layers made of the same type of elastic material laminated together, or may be made of different types of elastic materials laminated together.

[0018] The fibers 38 are included in the inner layer 32B, but not included in the surface layer 32A. In other words, the part of the roll body 32 that does not include the fibers 38 is referred to as the surface layer 32A, and the part of the roll body 32 that includes the fibers 38 is referred to as the inner layer 32B. The thickness of the surface layer 32A is sufficient to remain over the service life of the roll body 32, and is thinner than the inner layer 32B. This prevents the fibers 38 from being exposed to the outermost surface of the roll body 32 even if the roll body 32 is worn. Therefore, the roll body 32 is prevented from damaging the uncoated part 12B of the electrode plate 12 during pressing.

[0019] In order to reduce the difference in elongation between the coated portion 12A and the uncoated portion 12B of the electrode plate 12, it is necessary to increase the load when rolling only the uncoated portion 12B of the electrode plate 12 using the second rolling roll 24. However, since the uncoated portions 12B of the electrode plate 12 are located at both ends in the width direction of the electrode plate 12, if the load during rolling is increased, the elongation in the width direction of the uncoated portions 12B increases, and there is a risk of them breaking.

[0020] As described above, the roll barrel 32 of the second rolling roll 24 has a plurality of fibers 38 oriented in the axial direction of the second rolling roll 24. Therefore, the roll barrel 32 of the second rolling roll 24 is prevented from undergoing elastic deformation in the axial direction rather than in the circumferential direction during pressing. Since the elastic deformation in the axial direction of the roll barrel 32 is prevented, when the uncoated portion 12B of the electrode plate 12 is rolled, the elongation in the width direction of the uncoated portion 12B of the electrode plate 12 is prevented. Therefore, the load when rolling the uncoated portion 12B of the electrode plate 12 can be increased, so that the difference in elongation between the coated portion 12A and the uncoated portion 12B of the electrode plate 12 can be reduced. The roll press device 1 of this embodiment can reduce the difference in elongation between the coated portion 12A and the uncoated portion 12B of the electrode plate 12 while preventing the uncoated portion 12B of the electrode plate 12 from breaking.

[0021] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical usefulness alone or in combination. [Explanation of symbols]

[0022] 1: Roll press device 12: Electrode plate 12A: Coating section 12B: Uncoated area 14: Metal foil 16:Active material 22: First rolling roll 24: No. 2 rolling roll 32: Roll body 38: Fiber

Claims

1. A roll press device that rolls an electrode plate having a coated portion coated with an active material and an uncoated portion not coated with the active material arranged in a width direction, a first rolling roll that rolls only the coated portion of the electrode plate; and a second rolling roll that rolls only the uncoated portion of the electrode plate, The second roll includes a roll body portion made of an elastic material and a plurality of fibers contained in the roll body portion, The plurality of fibers are oriented in the axial direction of the second roll, A roll press device, wherein elastic deformation of the roll barrel of the second rolling roll is suppressed more in an axial direction than in a circumferential direction during rolling of the uncoated portion.

2. The roll barrel of the second rolling roll has a surface layer that contacts the uncoated portion of the electrode plate and an inner layer located below the surface layer, The roll press apparatus of claim 1 , wherein the plurality of fibers are included in the inner layer and are not included in the surface layer.

3. The roll press device according to claim 2 , wherein the surface layer and the inner layer are made of the same type of elastic material.

4. The roll press apparatus according to claim 2 or 3, wherein a thickness of the surface layer is smaller than a thickness of the inner layer.

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