Rolling device and rolling method for electrode plate

Abstract

The invention relates to an electrode plate rolling device and a rolling method. The present invention suppresses a difference in elongation between a plurality of unformed portions in an electrode sheet. The rolling device is provided with: a conveying device for conveying an electrode sheet in the longitudinal direction along a preset conveying path; a pair of pressing rollers disposed in a conveyance path of the electrode sheet and pressing the active material layer with the electrode sheet therebetween; and a straightening roller which is arranged on the upstream side or the downstream side of the pair of pressing rollers in the conveying path and extends in the width direction of the electrode sheet. The straightening roller is provided with: at least one small-diameter section provided at a position corresponding to the active material layer in the width direction of the electrode sheet; and a plurality of large-diameter parts around which the at least two non-formed parts are wound and which have an outer diameter larger than that of the small-diameter part. The large-diameter portions include a first large-diameter portion and a second large-diameter portion having an outer diameter larger than that of the first large-diameter portion.

Description

Technical Field

[0001] The invention relates to a rolling device and a rolling method for an electrode sheet. Background Art

[0002] For example, Japanese Patent Application Publication No. 6021508 discloses a device for pressing a strip electrode (electrode sheet), which has an active material layer coated with an active material slurry on a strip-shaped collector and an exposed portion of the collector where the active material layer is not present. The device described in Japanese Patent Application Publication No. 6021508 has a pressing roller for pressing the active material layer and a guide roller that also serves as a bending correction device. According to Japanese Patent Application Publication No. 6021508, the pressing pressure of the pressing roller is mainly applied to the active material layer and is hardly applied to the exposed portion of the collector. Therefore, the elongation of the exposed portion of the collector is smaller than that of the underlying collector containing the active material layer. As a result, the strip electrode is deformed or warped.

[0003] The guide roller described in Japanese Patent Application Publication No. 6021508 has a step portion in contact with the exposed portion of the current collector and a recessed portion facing the active material containing layer. According to Japanese Patent Application Publication No. 6021508, the tension applied in the conveying direction of the strip electrode plate can be concentrated on the exposed portion of the current collector. As a result, the exposed portion of the current collector can be stretched, and deformation and warping of the strip electrode plate can be corrected.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 6021508 Summary of the invention

[0007] Problems to be solved by the invention

[0008] According to the knowledge of the inventors, in an electrode sheet having a plurality of unformed portions where an active material layer is not formed, even if the unformed portions are stretched by step rollers as described in Japanese Patent Application Publication No. 6021508, the electrode sheet may be deformed due to the difference in elongation between the plurality of unformed portions. Therefore, the subject of the present invention is to suppress the difference in elongation between the plurality of unformed portions in the electrode sheet.

[0009] Solutions to Solve Problems

[0010] The rolling device for an electrode sheet disclosed herein is a rolling device for rolling an electrode sheet in which at least one active material layer and at least two unformed parts are alternately arranged along the width direction of a strip-shaped current collector and the unformed parts are arranged at both ends in the width direction. The rolling device comprises: a conveying device that conveys the electrode sheet in the length direction along a predetermined conveying path; a pair of pressing rollers that are arranged in the conveying path where the electrode sheet is conveyed by the conveying device and clamp the electrode sheet to press the active material layer; and a correction roller that is arranged on the upstream side or downstream side of the pair of pressing rollers in the conveying path and extends in the width direction of the electrode sheet. The correction roller comprises: at least one small diameter part that is respectively arranged at a position corresponding to the active material layer in the width direction of the electrode sheet; and a plurality of large diameter parts that are respectively hung around the at least two unformed parts and have an outer diameter larger than that of the small diameter part. The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than that of the first large diameter part.

[0011] According to the electrode sheet rolling device, the plurality of large diameter portions provided by the correction roller include: a first large diameter portion around which one unformed portion is hung; and a second large diameter portion around which another unformed portion is hung and whose outer diameter is larger than that of the first large diameter portion. The unformed portion hung around the second large diameter portion having an outer diameter larger than that of the first large diameter portion is elongated more than the unformed portion hung around the first large diameter portion. By the difference in elongation of the unformed portion caused by the difference in the outer diameter of such large diameter portions, the difference in elongation between the plurality of unformed portions can be adjusted and suppressed.

[0012] In addition, the rolling method of the electrode sheet disclosed herein is the following method: while conveying an electrode sheet in which at least one active material layer and at least two unformed parts are alternately arranged along the width direction of a strip-shaped current collector and the unformed parts are arranged at both ends in the width direction, the active material layer is pressed and the unformed part is stretched by a correction roller. The correction roller comprises: at least one small diameter part, which is respectively arranged at a position corresponding to the active material layer in the width direction of the electrode sheet; and a plurality of large diameter parts, which are respectively arranged at a position corresponding to the at least two unformed parts in the width direction of the electrode sheet and have an outer diameter larger than the small diameter part. The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than the first large diameter part. The rolling method disclosed herein includes the process of hanging the at least two unformed parts around the plurality of large diameter parts and applying tension to the electrode sheet.

[0013] The above-mentioned electrode sheet rolling method can also produce the same effects as those of the above-mentioned electrode sheet rolling device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is a schematic side view of a rolling device for an electrode sheet.

[0015] Figure 2 It is a schematic front view of the guide roller.

[0016] Figure 3 It is a schematic front view of the correction roller.

[0017] Figure 4 It is a three-dimensional diagram of the left accessory.

[0018] Figure 5 This is a flowchart of an operation for determining the outer diameter of the left large diameter portion and the outer diameter of the right large diameter portion. DETAILED DESCRIPTION

[0019] An embodiment of a rolling device for an electrode sheet of an electrical storage device is described below. The embodiment described here is not intended to limit the present invention. In addition, each figure is a schematic diagram and does not necessarily faithfully reflect an actual implementation product.

[0020] [Structure of rolling equipment]

[0021] Figure 1 It is a schematic side view of a rolling device 10 for an electrode sheet according to an embodiment. Here, the rolling device 10 is a device for rolling an electrode sheet 1 of a lithium-ion secondary battery. However, the electrode sheet 1 is not limited to an electrode sheet of a lithium-ion secondary battery, and may also be an electrode sheet of various known power storage devices. Power storage devices refer to all devices that can extract electric energy, including so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as double-layer capacitors.

[0022] The electrode sheet 1 includes a strip-shaped collector foil 2 and an active material layer 3 formed on the collector foil 2 (see Figure 2 ). The portion of the collector foil 2 where the active material layer 3 is not formed constitutes the unformed portion 4. The positive electrode sheet is a component in which a positive electrode active material layer 3 containing a positive electrode active material is formed on the surface of a strip-shaped collector foil 2 (such as an aluminum foil) of a predetermined width and thickness. The positive electrode active material is a material that can release lithium ions during charging and absorb lithium ions during discharge, such as a lithium transition metal composite material in a lithium ion secondary battery. In the positive electrode sheet, the active material layer 3 and the unformed portion 4 are protected by a protective layer. The negative electrode sheet is a component in which a negative electrode active material layer 3 containing a negative electrode active material is formed on the surface of a strip-shaped collector foil 2 (such as a copper foil) of a predetermined width and thickness. The negative electrode active material is a material that can absorb lithium ions during charging and release the lithium ions absorbed during discharge, such as natural graphite in a lithium ion secondary battery. For the positive electrode active material and the negative electrode active material, various materials other than the above-mentioned materials are proposed, and there is no particular limitation.

[0023] The raw material of the active material layer 3 is in the form of a slurry and is applied to the collector foil 2. The raw material of the active material layer 3 may be applied to one side or both sides of the collector foil 2. In the electrode sheet 1, at least one active material layer 3 and at least two unformed portions 4 are alternately arranged along the width direction of the strip-shaped collector foil 2. The unformed portions 4 are respectively arranged at both ends of the electrode sheet 1 in the width direction. Here, it is assumed that the electrode sheet 1 is an electrode sheet in which the active material layer 3 is formed in the central part in the width direction of the collector foil 2 and has unformed portions 4 at both ends (hereinafter, appropriately referred to as Figure 2 The unformed portion 4 on the left side is indicated by the reference numeral 4L, and the unformed portion 4 on the right side is indicated by the reference numeral 4R). However, the active material layer 3 may be formed in a plurality of strips in the width direction of the electrode sheet 1. In this case, a plurality of unformed portions 4 are formed at both ends of the electrode sheet 1 and between a plurality of active material layers 3. The rolling device 10 continuously presses the electrode sheet 1 while conveying it in the length direction, adjusts the thickness of the active material layer 3 to a thickness within a predetermined range, and densifies the active material in the active material layer 3.

[0024] like Figure 1 As shown, the rolling device 10 includes: a conveying device 20 for conveying the electrode sheet 1; a roller press 30 for pressing the electrode sheet 1; and a warping correction device 40 for suppressing warping or deformation of the electrode sheet 1 caused by pressing. The rolling device 10 may also include an inspection device, etc., but the description and illustration are omitted here.

[0025] The conveying device 20 conveys the electrode sheet 1 in the length direction along a preset conveying path. Here, the conveying device 20 includes a winding device 21, which is arranged at the most downstream of the rolling device 10 and winds up the rolled electrode sheet 1. The strip-shaped electrode sheet 1 is conveyed in the length direction by being wound by the winding device 21.

[0026] The roller press 30 includes a pair of rollers 31U and 31D for pressing the electrode sheet 1 between them, and a driving device 32 for driving the pair of rollers 31U and 31D. The pair of rollers 31U and 31D are arranged on a conveying path of the electrode sheet 1 conveyed by the conveying device 20, and press the active material layer 3 between them.

[0027] The warp correction device 40 is disposed at a position upstream of the roller press 30 on the conveying path of the electrode sheet 1. However, the warp correction device 40 may also be disposed at a position downstream of the roller press 30 on the conveying path of the electrode sheet 1. Figure 1As shown, the warp correction device 40 includes: clamping rollers 50U and 50D on the upstream and downstream sides; tension adjustment rollers 60U and 60D on the upstream and downstream sides; a plurality of guide rollers 70; a correction roller 80; and a wrap angle adjustment roller 90. When the active material layer 3 is pressed by the pressing rollers 31U and 31D, the collector foil 2 at the position where the active material layer 3 is formed is extended, and the unformed portion 4 is almost not extended. Therefore, a difference in elongation occurs between the position where the active material layer 3 is formed and the unformed portion 4, and deformation or warping occurs in the electrode sheet 1. The warp correction device 40 suppresses the warping or deformation of the electrode sheet 1 by pre-stretching the unformed portion 4 before pressing.

[0028] The clamping rollers 50U and 50D on the upstream and downstream sides divide the interval where high tension is applied to the electrode sheet 1. High tension is applied to the electrode sheet 1 between the clamping roller 50U on the upstream side and the clamping roller 50D on the downstream side. At a position upstream of the clamping roller 50U on the upstream side and downstream of the clamping roller 50D on the downstream side, the tension of the electrode sheet 1 can be adjusted to be weaker than the above-mentioned interval. The tension in the interval between the clamping roller 50U on the upstream side and the clamping roller 50D on the downstream side is applied by the tension adjustment roller 60U on the upstream side arranged in the interval. The tension adjustment roller 60D on the downstream side adjusts the tension of the electrode sheet 1 at a position downstream of the above-mentioned interval. The unformed portion 4 of the electrode sheet 1 is stretched by the tension applied in the interval between the clamping roller 50U on the upstream side and the clamping roller 50D on the downstream side.

[0029] The plurality of guide rollers 70 are rollers for turning the conveying direction of the electrode sheet 1. The conveying path of the electrode sheet 1 is wound around the plurality of guide rollers 70 so as to bend several times. Figure 2 70 is a schematic front view of the guide roller 70. Figure 2 As shown, the guide roller 70 includes a roller body 71 , a roller support member 72 , and a support wall 73 .

[0030] The roller body 71 is formed in a cylindrical shape and extends in the width direction of the electrode sheet 1. The electrode sheet is hung around the outer peripheral surface of the roller body 71. The roller support member 72 supports the roller body 71 so that it can rotate. Here, the roller support member 72 includes a pair of bearing portions 72a that receive both ends of the roller body 71. However, the structure of the roller support member 72 is not limited to this. The roller support member 72 may also include a rotating shaft around which the roller body 71 rotates, for example. In the present embodiment, the roller support member 72 supports both ends of the roller body 71, but it may also support only one end.

[0031] The support wall 73 is arranged on one side (here, the side 100 of the roller body 71 and the roller support member 72) in the width direction of the electrode sheet 1. Figure 2The roller support member 72 is supported at a position (to the left of the electrode sheet 1). The roller support member 72 is supported only on one side by the support wall 73. The support wall 73 is, for example, a wall portion extending vertically. However, the shape of the member that supports the roller support member 72 on one side is not particularly limited. The structure of the one-side support is based on the requirements of reducing the cost of the rolling device 10 and facilitating the operation of the electrode sheet 1 passing through the conveying path. However, due to this structure, when high tension is applied to the electrode sheet 1, the roller support member 72 is easily bent. The influence on the bending of the roller support member 72 will be described later.

[0032] The correction roller 80 is a roller for adjusting the elongation of the unformed portion 4 of the electrode sheet 1. Here, the correction roller 80 is arranged on the upstream side of the pair of pressing rollers 31U and 31D. The rolling device 10 of the present embodiment is configured to stretch the unformed portion 4 by the correction roller 80 before pressing the active material layer 3. However, the correction roller 80 can also be arranged on the downstream side of the pair of pressing rollers 31U and 31D. In this case, the process of stretching the unformed portion 4 by the correction roller 80 is performed after the process of pressing the active material layer 3.

[0033] Figure 3 It is a schematic front view of the correction roller 80. Figure 3 The left and right sides of Figure 2 The left and right sides of are consistent. Figure 3 As shown, the correction roller 80 includes a correction roller body 81, a roller support member 82, and a support wall 83. The roller support member 82 rotatably supports the correction roller body 81. The axial direction of the correction roller body 81 coincides with the width direction of the electrode sheet 1.

[0034] The structure of the roller support member 82 may be the same as or different from that of the roller support member 72 of the guide roller 70. Here, the roller support member 82 supports both left and right ends of the correction roller body 81. The support wall 83 is arranged on one side (here, the side) of the correction roller body 81 and the roller support member 82 in the width direction of the electrode sheet 1. Figure 3 The roller supporting member 82 is supported at a position (left side) of the guide roller 70. The roller supporting member 82 is also supported by only one side of the supporting wall 83. The correction roller body 81 of the correction roller 80 is supported on the same side as the roller body 71 of the guide roller 70. Hereinafter, the side of the end where the correction roller 80 and the plurality of guide rollers 70 are supported (herein, the left side) is also referred to as the supporting end side, and the side of the end that is not supported (herein, the right side) is referred to as the free end side. The supporting wall 83 may be a wall portion common to the supporting wall 73 of the guide roller 70, or may be a different wall portion.

[0035] like Figure 3As shown, the correction roller body 81 includes: at least one small diameter portion 84 respectively arranged at a position corresponding to the active material layer 3 in the width direction of the electrode sheet 1; and a plurality of large diameter portions 85 respectively hanging at least two unformed portions 4. The outer diameters of the plurality of large diameter portions 85 are larger than the outer diameters of the small diameter portions 84. The plurality of large diameter portions 85 are respectively arranged at positions corresponding to the plurality of unformed portions 4 in the width direction of the electrode sheet 1. The plurality of large diameter portions 85 are portions of the plurality of unformed portions 4 that are stretched and hung. The small diameter portion 84 is a portion that is retreated radially inward of the correction roller body 81 to avoid the active material layer 3. Through the small diameter portion 84 and the large diameter portion 85, the unformed portion 4 can be stretched without stretching the portion of the collector foil 2 where the active material layer 3 is formed.

[0036] like Figure 3 As shown, in the present embodiment, the small diameter portion 84 is provided at a position corresponding to the active material layer 3 in the central portion in the axial direction (the width direction of the electrode sheet 1) of the correction roller body 81. Here, the number of the small diameter portion 84 is 1. A plurality of large diameter portions 85 are arranged on the left and right of the small diameter portion 84. In the present embodiment, the number of the large diameter portions 85 is 2. However, the number of the small diameter portions 84 and the large diameter portions 85 varies depending on the number of the active material layers 3 and the unformed portions 4 arranged in the width direction of the electrode sheet 1. Hereinafter, when distinguishing between the two large diameter portions 85, the large diameter portion 85 on the left side (support end side) is also referred to as the left large diameter portion 85L, and the large diameter portion 85 on the right side (free end side) is referred to as the right large diameter portion 85R. The left large diameter portion 85L is connected to the left end portion of the small diameter portion 84. The right large diameter portion 85R is connected to the right end portion of the small diameter portion 84.

[0037] The small diameter portion 84 faces the active material layer 3 and is separated from the active material layer 3 in a state where the non-formed portion 4 of the electrode sheet 1 is hung around the large diameter portion 85 .

[0038] The left large diameter portion 85L and the right large diameter portion 85R are formed to have a diameter that is about 1 mm to 2 mm larger than the small diameter portion 84. The diameter DL of the left large diameter portion 85L is different from the diameter DR of the right large diameter portion 85R. In the present embodiment, the diameter DL of the left large diameter portion 85L on the support end side is larger than the diameter DR of the right large diameter portion 85R on the free end side. The difference between the diameter DL of the left large diameter portion 85L and the diameter DR of the right large diameter portion 85R is, for example, about 0.05 mm to 0.1 mm. However, the difference between the diameter DL of the left large diameter portion 85L and the diameter DR of the right large diameter portion 85R is set based on the measured value of the elongation of the left and right unformed portions 4L and 4R as described later, and is not particularly limited. In addition, based on the measured value of the elongation of the left and right unformed portions 4L and 4R, the diameter DR of the right large diameter portion 85R on the free end side may also be larger than the diameter DL of the left large diameter portion 85L on the support end side.

[0039] The left large diameter portion 85L and the right large diameter portion 85R are respectively in contact with the left and right unformed portions 4L and 4R at a position at a predetermined distance from the left and right ends of the active material layer 3 in the width direction. For example, the left large diameter portion 85L and the right large diameter portion 85R are respectively arranged so that the inner edges are in contact with the central portion in the left-right direction of the unformed portion 4L and 4R or a portion slightly inward of the central portion. Thus, while stretching the unformed portions 4L and 4R (and the protective layer in the case of the positive electrode sheet), the active material layer 3 is suppressed from extending together. However, the position of the unformed portion 4L and 4R that is in contact with the left large diameter portion 85L and the right large diameter portion 85R is not limited to the above-mentioned position.

[0040] The correction roller 80 of this embodiment includes a plurality of types of left attachments 86L constituting the outer peripheral portion of the left large diameter portion 85L and having different outer diameters. The correction roller 80 includes a left mounted portion 87L to which any of the plurality of types of left attachments 86L is mounted. Figure 4 is a three-dimensional diagram of the left accessory 86L. Figure 4 As shown, the left fitting 86L is configured in a cylindrical shape. The outer diameter DL1 of the left fitting 86L varies depending on the type of the left fitting 86L. The outer diameter DL1 of the selected left fitting 86L becomes the outer diameter DL of the left large diameter portion 85L. The inner diameter DL2 of the left fitting 86L is the same regardless of the type of the left fitting 86L, ​​and is equal to the outer diameter of the left mounted portion 87L.

[0041] Similar to the left large diameter portion 85L, the correction roller 80 includes a plurality of types of right fittings 86R that constitute the outer periphery of the right large diameter portion 85R and have different outer diameters. The correction roller 80 includes a right mounted portion 87R to which any one of the plurality of types of right fittings 86R is mounted. The right fitting 86R and the right mounted portion 87R are configured similarly to the left fitting 86L and the left mounted portion 87L, respectively.

[0042] In the present embodiment, the correction roller 80 includes a plurality of types of left accessories 86L and a plurality of types of right accessories 86R, which respectively constitute the outer peripheries of the left large diameter portion 85L and the right large diameter portion 85R and have different outer diameters. However, the correction roller 80 may include only a plurality of types of left accessories 86L or a plurality of types of right accessories 86R, which constitute the outer peripheries of the left large diameter portion 85L or the right large diameter portion 85R and have different outer diameters. In this case, the right large diameter portion 85R or the left large diameter portion 85L may be configured so that the outer diameter cannot be changed. By changing the outer diameter of only one of the large diameter portions 85, the difference between the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R can be adjusted.

[0043] The wrap angle adjustment roller 90 is a roller for adjusting the wrap angle of the electrode sheet 1 when it is wound around the correction roller 80. The wrap angle adjustment roller 90 is provided adjacent to the correction roller 80 and is configured to be movable in a direction perpendicular to the axis so as to adjust the wrap angle of the correction roller 80.

[0044] [Reason for making the diameters of the left and right large diameter parts different]

[0045] The following is an explanation of the reason for making the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R different. As described above, in the rolling device 10 of the present embodiment, the plurality of guide rollers 70 are supported on one side. Therefore, when high tension is applied to the electrode sheet 1, the free end side of the guide roller 70 is bent due to the tension, while on the other hand, the bending of the support end side of the guide roller 70 is small. As a result, the conveying path of the electrode sheet 1 becomes longer on the free end side, and the unformed portion 4R on the free end side is longer than the unformed portion 4L on the support end side. The correction roller 80 corrects the difference in elongation between the unformed portion 4 on the free end side and the support end side by making the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R different.

[0046] In the present embodiment, the diameter DL of the left large diameter portion 85L on the support end side is larger than the diameter DR of the right large diameter portion 85R on the free end side. Therefore, the unformed portion 4L on the support end side of the left large diameter portion 85L is stretched by the correction roller 80 to be longer than the unformed portion 4R on the free end side of the right large diameter portion 85R. As a result, the difference in the amount of elongation between the unformed portion 4R on the free end side and the unformed portion 4L on the support end side caused by the one-sided support of the guide roller 70 is reduced.

[0047] Table 1 shows the difference in elongation between the left and right unformed portions 4L and 4R when the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R are different (Example), and the difference in elongation between the left and right unformed portions 4L and 4R when the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R are the same (Comparative Example). As shown in Table 1, in the Example, the difference in elongation between the left and right unformed portions 4L and 4R is smaller than in the Comparative Example.

[0048]

Table 1

[0049] In addition, due to other factors such as the state of the electrode sheet 1, the elongation of the left and right unformed portions 4L and 4R may also differ. For example, even if the guide roller 70, the correction roller 80 and other rollers are all supported at both ends instead of one side, the elongation of the left and right unformed portions 4L and 4R may differ. For example, in the case where the collector foil 2 originally has a thickness difference on the left and right, even if tension is applied equally to the left and right unformed portions 4, there may be a difference in the elongation of the left and right unformed portions 4. Therefore, which of the two (or more than three) large diameter portions 85 of the correction roller 80 has a larger outer diameter and which has a smaller outer diameter can be changed without limitation.

[0050] [Stretching process of unformed portion]

[0051] In this embodiment, the elongation of the plurality of unformed portions 4 is measured in advance, and the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R are determined based on the measured elongation. Then, the unformed portion 4 of the electrode sheet 1 is actually stretched under the determined conditions. An example of the procedure is described below.

[0052] Figure 5 85L and the outer diameter DR of the right large diameter portion 85R and the process of stretching the unformed portion 4. Figure 5 As shown, the process of stretching the unformed portion 4 includes steps S01 to S05 of determining the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R. The process of stretching the unformed portion 4 also includes step S06 of hanging at least two unformed portions 4 around the plurality of large diameter portions 85 and applying tension to the electrode sheet 1.

[0053] like Figure 5 As shown, in step S01 of the process of determining the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R, the left and right unformed portions 4L and 4R are actually stretched using the end portions in the longitudinal direction of the electrode sheet 1. In step S01, the electrode sheet 1 is passed between a pair of rollers of the upstream and downstream clamping rollers 50U and 50D, and the electrode sheet 1 is hung around the rollers of the warpage correction device 40. Thereafter, the rollers of the warpage correction device 40 are driven, and tension is applied to the electrode sheet 1 by the tension adjustment roller 60U. As a result, the electrode sheet 1 is conveyed along the conveying path, and the left and right unformed portions 4L and 4R are stretched.

[0054] In the next step S02, the elongation of the unformed portion 4L stretched by the left large diameter portion 85L and the elongation of the unformed portion 4R stretched by the right large diameter portion 85R are measured. In step S03, the difference between the elongation of the unformed portion 4L and the elongation of the unformed portion 4R is obtained, and it is determined whether the obtained difference in elongation is less than a preset threshold value. If the difference in elongation is less than the threshold value (if the result of step S03 is yes), in step S05, it is determined that the left fitting 86L and the right fitting 86R are used as they are without changing. If the difference in elongation exceeds the threshold value (if the result of step S03 is no), in step S04, the outer diameter of at least one of the left large diameter portion 85L and the right large diameter portion 85R is adjusted based on the measured elongation of the unformed portions 4L, 4R. In step S04, at least one of the left fitting 86L and the right fitting 86R is replaced so as to eliminate the difference in elongation obtained in step S03. In step S04 , any one of the plurality of types of left accessories 86L and one or more types of right accessories 86R are selected and mounted on the correction roller 80 .

[0055] After step S04, steps S01 to S03 are performed again. When the result of step S03 becomes yes due to the repetition of steps S01 to S04, the left fitting 86L and the right fitting 86R to be used are determined in step S05. Step S06 of stretching the unformed portion 4 as a production process of the adjusted electrode sheet 1 is the same as step S01.

[0056] [Effects of implementation methods]

[0057] Hereinafter, the effects that can be achieved by the rolling device 10 for the electrode sheet 1 according to the present embodiment and the process using the rolling device 10 will be described.

[0058] The rolling device 10 of the electrode sheet 1 of the present embodiment is a rolling device for rolling the electrode sheet 1 in which at least one active material layer 3 and at least two unformed portions 4 are alternately arranged along the width direction of the strip-shaped collector foil 2. The unformed portions 4 are arranged at both ends in the width direction of the electrode sheet 1. The rolling device 10 includes: a conveying device 20 that conveys the electrode sheet 1 in the longitudinal direction along a predetermined conveying path; a pair of pressing rollers 31U and 31D that are arranged in the conveying path where the electrode sheet 1 is conveyed by the conveying device 20, and press the active material layer 3 by sandwiching the electrode sheet 1; and a correction roller 80 that is arranged on the upstream side of the pair of pressing rollers 31U and 31D in the conveying path of the electrode sheet 1 and extends in the width direction of the electrode sheet 1. The correction roller 80 includes: at least one small diameter portion 84 that is respectively arranged at a position corresponding to the active material layer 3 in the width direction of the electrode sheet 1; and a plurality of large diameter portions 85 that are respectively hung around at least two unformed portions 4 and have an outer diameter larger than that of the small diameter portion 84. The plurality of large diameter portions 85 include a first large diameter portion and a second large diameter portion whose outer diameter is larger than the first large diameter portion. In this embodiment, the first large diameter portion is the right large diameter portion 85R. The second large diameter portion is the left large diameter portion 85L.

[0059] According to the rolling device 10, the unformed portion 4L hung on the second large diameter portion (here, the left large diameter portion 85L) having an outer diameter larger than the first large diameter portion (here, the right large diameter portion 85R) is elongated compared to the unformed portion 4R hung on the first large diameter portion. As described above, the elongation of the plurality of unformed portions 4 may differ depending on the structure of the rolling device 10, the state of the electrode sheet 1, etc. According to the rolling device 10 of the present embodiment, the difference in elongation between the plurality of unformed portions 4 as described above can be adjusted by the difference in elongation of the unformed portion 4 caused by the difference in the outer diameter of the large diameter portion 85. As a result, the difference in elongation between the plurality of unformed portions 4 can be suppressed.

[0060] In the present embodiment, the correction roller 80 is arranged on the upstream side of a pair of pressing rollers 31U and 31D. According to this structure, the possibility of the electrode sheet 1 breaking during the pressing process of the active material layer 3 can be reduced. The correction roller 80 can also be arranged on the downstream side of the pair of pressing rollers 31U and 31D. However, in the case where the unformed portion 4 is stretched before the pressing process of the active material layer 3, the possibility of the electrode sheet 1 breaking due to the inability of the unformed portion 4 to follow the elongation of the active material layer 3 during the pressing process can be further reduced. In addition, the rolling device 10 may also have other correction rollers on the downstream side of the pair of pressing rollers 31U and 31D arranged in the conveying path, and may also be configured to correct the warping of the electrode sheet 1 before and after pressing.

[0061] The rolling device 10 of the present embodiment further includes a guide roller 70, which is arranged at a position on the upstream side or downstream side of the conveying path relative to the correction roller 80, and around which the electrode sheet 1 is hung. The guide roller 70 includes: a roller body 71 extending in the width direction of the electrode sheet 1; a roller support member 72 that supports the roller body 71 so as to be rotatable; and a support wall 83, which is arranged at a position closer to one side (here, the left side) in the width direction of the electrode sheet 1 than the roller body 71 and the roller support member 72, and supports the roller support member 72. The roller support member 82 is supported by only one side of the support wall 83. The second large diameter portion having a larger outer diameter, here, the left large diameter portion 85L, is arranged at a position closer to the above-mentioned one side (i.e., the left side and the support end side) in the width direction of the electrode sheet 1 than the first large diameter portion having a smaller outer diameter, here, the right large diameter portion 85R.

[0062] As described above, since the guide roller 70 is supported on one side of the support end side, the unformed portion 4R on the free end side is stretched by the guide roller 70 to be longer than the unformed portion 4L on the support end side. On the other hand, according to the structure of the correction roller 80 as described above, the unformed portion 4L on the support end side hung around the left large diameter portion 85L having a larger outer diameter is stretched by the correction roller 80 to be longer than the unformed portion 4R on the free end side hung around the right large diameter portion 85R. Therefore, by being hung around the correction roller 80, the difference in the amount of elongation of the unformed portion 4 on the free end side and the support end side caused by the one-sided support of the guide roller 70 is reduced.

[0063] In the present embodiment, the left large diameter portion 85L and the right large diameter portion 85R are respectively configured to be able to adjust the outer diameter. According to this structure, the difference between the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R can be adjusted according to which one of the unformed portion 4L on the left and the unformed portion 4R on the right is stretched longer than the other. Thus, the difference in elongation between the unformed portion 4L on the left and the unformed portion 4R on the right can be further suppressed. In addition, as long as at least one of the left large diameter portion 85L and the right large diameter portion 85R is configured to be able to adjust the outer diameter, the same effect can be exerted.

[0064] In the present embodiment, the correction roller 80 includes a plurality of types of left fittings 86L constituting the outer periphery of the left large diameter portion 85L and having different outer diameters, and a plurality of types of right fittings 86R constituting the outer periphery of the right large diameter portion 85R and having different outer diameters. The correction roller 80 includes a left mounted portion 87L to which any one of the plurality of types of left fittings 86L is mounted, and a right mounted portion 87R to which any one of the plurality of types of right fittings 86R is mounted. According to this structure, the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R can be easily adjusted by replacing the fittings 86L and 86R.

[0065] The rolling method of the electrode sheet 1 of the present embodiment includes: step S02 of measuring the elongation of the unformed portion 4L stretched by the left large diameter portion 85L and the elongation of the unformed portion 4R stretched by the right large diameter portion 85R; and step S04 of adjusting the outer diameter of at least one of the left large diameter portion 85L and the right large diameter portion 85R based on the measured elongation of the unformed portions 4L and 4R. According to this method, it can be known in step S02 which of the unformed portion 4L on the left and the unformed portion 4R on the right is stretched longer than the other. In addition, in step S04, the difference between the outer diameter DL of the left large diameter portion 85L and the outer diameter DR of the right large diameter portion 85R can be adjusted according to the result of step S02. Thus, the difference in elongation between the unformed portion 4L on the left and the unformed portion 4R on the right can be suppressed.

[0066] The rolling device 10 of the present embodiment is particularly effective when rolling a positive electrode sheet in which the collector foil 2 is composed of aluminum foil and the active material layer 3 is a positive electrode active material layer. For the positive electrode sheet, it is desired to strongly press the active material layer 3 to increase the density of the positive electrode active material, but the warping or deformation of the positive electrode sheet is likely to increase. In addition, the positive electrode active material is usually harder than the negative electrode active material, so high pressure is required to obtain the desired compression rate, and the elongation of the active material layer 3 increases accordingly. Therefore, the target value of the elongation of the unformed portion 4 also increases, and the difference in elongation between the unformed portion 4L on the left and the unformed portion 4R on the right tends to increase. Therefore, the rolling device 10 of the present embodiment is particularly effective when rolling a positive electrode sheet in which the collector foil 2 is composed of aluminum foil and the active material layer 3 is a positive electrode active material layer. [Other embodiments]

[0067] An embodiment of the rolling device for the electrode sheet proposed herein has been described above. However, the above embodiment is only an example and can also be implemented in other ways. For example, in the above embodiment, the large diameter portion is provided at both ends of the correction roller body, and the outer diameter of the large diameter portion of one side is larger than the outer diameter of the large diameter portion of the other side. However, the correction roller corresponding to the electrode sheet having more than three unformed portions may also have more than three large diameter portions, and the large diameter portion having an outer diameter larger or smaller than that of other large diameter portions may also be the large diameter portion other than the two ends. In addition, in the correction roller having more than three large diameter portions, the outer diameters of the plurality of large diameter portions may also be three or more.

[0068] In the above-mentioned embodiment, the outer diameter of the large diameter portion is changed by selecting the accessories. However, the method of adjusting the outer diameter of the large diameter portion is not limited to this. The outer diameter of the large diameter portion can also be adjusted by, for example, winding a member such as a strip around the outer periphery of the large diameter portion. As long as the rolling conditions are stable, the outer diameters of the plurality of large diameter portions can also be fixed so as not to be adjustable.

[0069] In addition, the above-mentioned embodiments do not limit the present invention unless otherwise specified. In addition, the technology disclosed herein can be modified in various ways, and each component and each process mentioned herein can be appropriately omitted or appropriately combined as long as no particular problem occurs.

[0070] This specification includes the disclosure described in the following items.

[0071] Item 1:

[0072] A rolling device for an electrode sheet, the rolling device rolling an electrode sheet in which at least one active material layer and at least two unformed portions are alternately arranged along the width direction of a strip-shaped current collector and the unformed portions are arranged at both ends in the width direction, wherein the rolling device comprises:

[0073] A conveying device, which conveys the electrode sheet in a length direction along a preset conveying path;

[0074] a pair of pressing rollers disposed on a conveying path of the electrode sheet conveyed by the conveying device, and sandwiching the electrode sheet to press the active material layer; and

[0075] a correction roller, which is arranged on the upstream side or downstream side of the pair of pressing rollers in the conveying path and extends in the width direction of the electrode sheet,

[0076] The correction roller comprises:

[0077] at least one small-diameter portion, which is provided at a position corresponding to the active material layer in the width direction of the electrode sheet; and

[0078] A plurality of large diameter portions, which are respectively hung around the at least two unformed portions and have an outer diameter larger than that of the small diameter portion,

[0079] The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than the first large diameter part.

[0080] Item 2:

[0081] In the rolling device described in Item 1, the correction roll is arranged on the upstream side of the pair of press rolls.

[0082] Item 3:

[0083] The rolling device described in item 1 or 2 further includes a guide roller, which is arranged at an upstream side or a downstream side of the conveying path relative to the correction roller and around which the electrode sheet is hung.

[0084] The guide roller has:

[0085] a roller body extending in the width direction of the electrode sheet;

[0086] a first supporting member that rotatably supports the roller body; and

[0087] a second supporting member disposed on one side in the width direction relative to the roller body and the first supporting member, and supporting the first supporting member;

[0088] The first supporting member is supported by only one side of the second supporting member,

[0089] The second large diameter portion is arranged on the one side in the width direction relative to the first large diameter portion.

[0090] Item 4:

[0091] In the rolling device according to any one of items 1 to 3, at least one of the first large diameter portion and the second large diameter portion is configured to be able to adjust the outer diameter.

[0092] Item 5:

[0093] In the rolling device described in item 4, the correction roll includes:

[0094] a plurality of types of accessories constituting the outer periphery of at least one of the first large-diameter portion and the second large-diameter portion and having different outer diameters; and

[0095] A mounted portion to which any one of the plurality of types of accessories is mounted.

[0096] Item 6:

[0097] In the rolling device described in any one of items 1 to 5, the electrode sheet is a positive electrode sheet in which the current collector is composed of an aluminum foil and the active material layer is a positive electrode active material layer.

[0098] Item 7:

[0099] A method for rolling an electrode sheet, in which an electrode sheet having at least one active material layer and at least two unformed portions alternately arranged along the width direction of a strip-shaped current collector and having the unformed portions arranged at both ends in the width direction is conveyed, the active material layer is pressed, and the unformed portion is stretched by a correction roller, wherein:

[0100] The correction roller comprises:

[0101] at least one small-diameter portion, which is provided at a position corresponding to the active material layer in the width direction of the electrode sheet; and

[0102] a plurality of large diameter portions, which are respectively arranged at positions corresponding to the at least two unformed portions in the width direction of the electrode sheet and have an outer diameter larger than that of the small diameter portion,

[0103] The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than the first large diameter part,

[0104] The rolling method includes the step of hanging the at least two unformed portions around the plurality of large-diameter portions, respectively, and applying tension to the electrode sheet.

[0105] Item 8:

[0106] In the rolling method described in Item 7, before the active material layer is pressed, the unformed portion is stretched by the correction roll.

[0107] Item 9:

[0108] In the rolling method described in item 7 or 8, it includes:

[0109] a step of measuring the elongation of the unformed portion stretched by the first large diameter portion and the elongation of the unformed portion stretched by the second large diameter portion; and

[0110] A step of adjusting an outer diameter of at least one of the first large-diameter portion and the second large-diameter portion based on the measured elongation of the unformed portion.

[0111] Item 10:

[0112] In the rolling method described in item 9, in the step of adjusting the outer diameter, any one of a plurality of types of attachments constituting the outer periphery of at least one of the first large diameter portion and the second large diameter portion and having different outer diameters is attached to the correction roll.

[0113] Item 11:

[0114] In the rolling method described in any one of items 7 to 10, the electrode sheet is a positive electrode sheet in which the current collector is composed of an aluminum foil and the active material layer is a positive electrode active material layer. Description of Reference Numerals

[0115] 1 electrode sheet

[0116] 2. Collector foil (collector)

[0117] 3 Active material layer

[0118] 4 Unformed part

[0119] 10Rolling device

[0120] 20Conveying device

[0121] 21. Coiler

[0122] 30 Roller Press

[0123] 31U, 31D pressure roller

[0124] 32 drive device

[0125] 40Warp correction device

[0126] 50U, 50D clamping roller

[0127] 60U, 60D tension adjustment roller

[0128] 70 guide roller

[0129] 71 Roller body

[0130] 72 roller supporting member (first supporting member)

[0131] 72a Bearing

[0132] 73 Support wall (second support member)

[0133] 80 correction roller

[0134] 81 Correction roller body

[0135] 82 Roller support member

[0136] 83 Support wall

[0137] 84 Trail Section

[0138] 85 large diameter part

[0139] 85L left large diameter part (second largest diameter part)

[0140] 85R right large diameter part (first large diameter part)

[0141] 86L left accessories

[0142] 86R right accessories

[0143] 87L left mounted part

[0144] 87R right mounted part

[0145] 90° wrap angle adjustment roller.

Claims

1. A rolling device for an electrode sheet, wherein the rolling device rolls an electrode sheet in which at least one active material layer and at least two unformed portions are alternately arranged along the width direction of a strip-shaped current collector and the unformed portions are arranged at both ends in the width direction, wherein: The rolling device comprises: A conveying device, which conveys the electrode sheet in a length direction along a preset conveying path; a pair of pressing rollers, arranged on a conveying path of the electrode sheet conveyed by the conveying device, and sandwiching the electrode sheet to press the active material layer; as well as a correction roller, which is arranged on the upstream side or downstream side of the pair of pressing rollers in the conveying path and extends in the width direction of the electrode sheet, The correction roller has: at least one small-diameter portion, which is provided at a position corresponding to the active material layer in the width direction of the electrode sheet; and A plurality of large diameter portions, which are respectively hung around the at least two unformed portions and have an outer diameter larger than that of the small diameter portion, The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than the first large diameter part.

2. The rolling device according to claim 1, wherein: The correction roller is arranged on the upstream side of the pair of press rollers.

3. The rolling device according to claim 1, wherein: A guide roller is further provided, the guide roller being arranged at an upstream side or a downstream side of the conveying path relative to the correction roller, and around which the electrode sheet is hung. The guide roller comprises: a roller body extending in the width direction of the electrode sheet; a first supporting member that rotatably supports the roller body; and a second supporting member disposed on one side in the width direction relative to the roller body and the first supporting member, and supporting the first supporting member; The first supporting member is supported by only one side of the second supporting member, The second large diameter portion is arranged on the one side in the width direction relative to the first large diameter portion.

4. The rolling device according to claim 1, wherein: At least one of the first large diameter portion and the second large diameter portion is configured to be able to adjust an outer diameter.

5. The rolling device according to claim 4, wherein: The correction roller has: a plurality of types of accessories constituting the outer periphery of at least one of the first large-diameter portion and the second large-diameter portion and having different outer diameters; and A mounted portion to which any one of the plurality of types of accessories is mounted.

6. The rolling device according to claim 1, wherein: The electrode sheet is a positive electrode sheet in which the current collector is composed of aluminum foil and the active material layer is a positive electrode active material layer.

7. A method for rolling an electrode sheet, in which an electrode sheet having at least one active material layer and at least two unformed portions alternately arranged along the width direction of a strip-shaped current collector and having the unformed portions arranged at both ends in the width direction is conveyed, the active material layer is pressed, and the unformed portion is stretched by a correction roller, wherein: The correction roller has: at least one small-diameter portion, which is provided at a position corresponding to the active material layer in the width direction of the electrode sheet; and a plurality of large diameter portions, which are respectively arranged at positions corresponding to the at least two unformed portions in the width direction of the electrode sheet and have an outer diameter larger than that of the small diameter portion, The plurality of large diameter parts include a first large diameter part and a second large diameter part having an outer diameter larger than the first large diameter part, The rolling method includes the step of hanging the at least two unformed portions around the plurality of large-diameter portions, respectively, and applying tension to the electrode sheet.

8. The rolling method according to claim 7, wherein: Before the active material layer is pressed, the unformed portion is stretched by the correction roll.

9. The rolling method according to claim 7, wherein: The rolling method comprises: a step of measuring the elongation of the unformed portion stretched by the first large diameter portion and the elongation of the unformed portion stretched by the second large diameter portion; and A step of adjusting an outer diameter of at least one of the first large-diameter portion and the second large-diameter portion based on the measured elongation of the unformed portion.

10. The rolling method according to claim 9, wherein: In the step of adjusting the outer diameter, any one of a plurality of types of attachments constituting the outer peripheral portion of at least one of the first large diameter portion and the second large diameter portion and having different outer diameters is attached to the correction roller.

11. The rolling method according to claim 7, wherein: The electrode sheet is a positive electrode sheet in which the current collector is composed of aluminum foil and the active material layer is a positive electrode active material layer.

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