Electrode sheet manufacturing apparatus and electrode sheet manufacturing method

Abstract

The invention relates to an electrode sheet manufacturing apparatus and an electrode sheet manufacturing method. The electrode sheet manufacturing apparatus includes a conveying device, a first pressing device, a second pressing device, and a stepped roller pressing device. The first pressing device is a device for rolling an unformed portion of an electrode sheet by using a pair of rubber rollers. The second pressing device is a device for rolling the active material layer. The step roller pressing device is a device for applying tension by pressing a step roller on an unformed part of an electrode sheet. The upper roller includes a shaft and an elastic body. The diameter of the shaft at a position where the boundary portion between the unformed portion and the active material layer is pressed is larger than the diameter of the shaft at a position where the outside of the boundary portion is pressed. The thickness of the elastic body at a portion pressing the boundary portion is thinner than the thickness of the elastic body at a portion pressing the outside of the boundary portion.

Description

Technical Field

[0001] This invention relates to an electrode sheet manufacturing apparatus and a method for manufacturing electrode sheets. Background Technology

[0002] Japanese Patent Application Publication No. 2023-036089 discloses a method for manufacturing an electrode, which includes a coating pressing process for pressing a coating portion disposed on a metal foil in the thickness direction and an uncoated portion pressing process for pressing an uncoated portion in the thickness direction.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-036089 Summary of the Invention

[0006] However, the inventors have discovered that when the electrode sheet is rolled, even when a pair of elastic rollers are used to press the uncoated portion, wrinkles still occur on the electrode sheet.

[0007] The electrode sheet manufacturing apparatus disclosed herein is an apparatus for manufacturing an electrode sheet having a current collector, an unformed portion, and an active material layer. The current collector is composed of a strip of metal foil. The unformed portion is positioned along its length at a predetermined location in the width direction of the current collector. The active material layer is formed in the portion of the current collector excluding the unformed portion. The electrode sheet manufacturing apparatus includes a conveying device, a first pressing device, a second pressing device, and a roller pressing device. The conveying device conveys the electrode sheet along a predetermined conveying path. The first pressing device is disposed on the conveying path and uses a pair of rubber rollers to press the unformed portion of the electrode sheet. The second pressing device is disposed downstream of the first pressing device on the conveying path and presses the active material layer. The stepped roller pressing device is disposed downstream of the second pressing device on the conveying path and applies tension by pressing the stepped roller against the unformed portion of the electrode sheet. The stepped roller has a step at the portion that contacts the boundary portion of the unformed portion that contacts the active material layer. In the stepped roller, the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer. At least one of a pair of rubber rollers includes a shaft and an elastomer wound on the shaft. In the at least one rubber roller, the diameter of the shaft at the portion pressing the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft at the portion pressing the outer side of the boundary portion. In the at least one rubber roller, the thickness of the elastomer at the portion pressing the boundary portion is thinner than the thickness of the elastomer at the portion pressing the outer side of the boundary portion. According to this electrode sheet manufacturing apparatus, wrinkles in the electrode sheet are easily suppressed. Attached Figure Description

[0008] Figure 1 This is a flowchart of the manufacturing process for the electrode sheet.

[0009] Figure 2 This is a schematic diagram of electrode 10.

[0010] Figure 3 This is a schematic diagram showing another configuration of the electrode sheet 10.

[0011] Figure 4 This is a schematic diagram illustrating an example of the rolling process S6 presented herein.

[0012] Figure 5 This is a schematic diagram of the first pressing device 104.

[0013] Figure 6 This is a schematic diagram of the stepped roller pressing process S6c.

[0014] Figure 7 This is a schematic diagram showing the elongation of the electrode sheet 10 being rolled in the first pressing process S6a.

[0015] Figure 8 This is a schematic diagram showing the elongation of the current collector 12. Detailed Implementation

[0016] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the accompanying drawings. The embodiments described herein are not intended to specifically limit the invention. The drawings are schematic and do not necessarily reflect the actual object. Furthermore, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repeated descriptions are appropriately omitted. In this specification, expressions such as "X~Y" indicating numerical ranges, unless otherwise specified, refer to "X and above and Y and below".

[0017] Figure 1 This is a flowchart of the manufacturing process for the electrode sheet. For example... Figure 1 As shown, the method for manufacturing an electrode sheet includes a conveying process S1, a metering process S2, a mixing process S3, a coating process S4, a drying process S5, and a rolling process S6. However, the method for manufacturing an electrode sheet may also include other processes.

[0018] <Electrode Plate 10>

[0019] Figure 2 This is a schematic diagram of electrode plate 10. Electrode plate 10 constitutes the positive or negative electrode plate of the electrode body housed inside the energy storage device. Energy storage device refers to a device that can be repeatedly charged and discharged. In addition to so-called storage batteries (i.e., chemical batteries) such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, it also includes capacitors (i.e., physical batteries) such as electric double-layer capacitors.

[0020] like Figure 2 As shown, the electrode sheet 10 includes a current collector 12 and an active material layer 14. The current collector 12 is a component made of metal foil. The current collector 12 is a long strip-shaped metal component. As the current collector 12, a metal material with the desired conductivity can be used. As the positive electrode current collector foil, aluminum, aluminum alloy, etc., can be used, for example. As the negative electrode current collector foil, copper, copper alloy, etc., can be used, for example. The active material layer 14 is applied to a predetermined position in the current collector 12. The active material layer 14 is formed on at least one surface of the strip-shaped current collector 12. In this embodiment, the active material layer 14 is formed on both surfaces of the current collector 12. The active material layer 14 is a layer containing electrode active material. As the positive electrode active material, lithium transition metal composite oxide, for example, can be used. As the negative electrode active material, carbon materials, silicon-based materials, and their mixed oxides, for example, can be used. The active material layer may also contain additives other than the electrode active material, such as binders and conductive materials.

[0021] The electrode sheet 10 is formed by coating an electrode composite material slurry, which serves as an active material layer 14, onto a current collector 12 and then drying it. Uncoated portions 12a (unformed portions) and coated portions 12b are provided on the current collector 12. The uncoated portions 12a are the parts of the current collector 12 where the active material layer 14 is not coated. The uncoated portions 12a are located along the length direction at the ends of the electrode sheet 10 in the width direction. In this embodiment, the uncoated portions 12a are located at both ends of the electrode sheet 10 in the width direction. The coated portions 12b are disposed between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode composite material slurry is applied to the coated portions 12b. Thus, the active material layer 14 is formed in the coated portions 12b of the current collector 12. That is, the active material layer 14 is disposed between the uncoated portions 12a at both ends of the electrode sheet 10 in the width direction. Thus, the electrode sheet 10 may have: a current collector 12 made of a strip of metal foil, an unformed portion (here, an uncoated portion 12a) set at a predetermined position in the width direction along the length direction in the current collector 12, and an active material layer 14 formed in the current collector 12 in the portion other than the unformed portion.

[0022] Figure 3 This is a schematic diagram illustrating other configurations of the electrode sheet 10. For example... Figure 3As shown, an insulating protective layer 12c can be provided on the electrode sheet 10 at a position adjacent to the coated portion 12b in the uncoated portion 12a. This structure can be used, for example, in the electrode sheet 10 used for the positive electrode. By providing this protective layer 12c on the electrode sheet 10 used for the positive electrode, short circuits between the positive electrode current collector foil and the negative electrode active material layer can be prevented. The protective layer 12c contains an insulating inorganic filler. An example of an inorganic filler is insulating particles, such as ceramic particles like alumina. The protective layer 12c may also contain an adhesive, for example. The adhesive can be the same as that exemplified as an adhesive that can be included in the positive electrode active material layer. Hereinafter, the constituent elements of the electrode sheet 10 will be appropriately referred to, even if not specifically mentioned. Figure 2 as well as Figure 3 .

[0023] <Conveying process S1, Metering process S2, Mixing process S3, Coating process S4, Drying process S5>

[0024] exist Figure 1 In the conveying process S1 shown, the electrode sheet 10 is conveyed. In the conveying process S1, the electrode sheet 10 is conveyed along a predetermined conveying path W1 (refer to...). Figure 4 The active material layer 14 (refer to step S2) is conveyed. Figure 2 The raw material for the active material layer 14 is measured. This measurement can be achieved, for example, by a measuring device (not shown) equipped with a balance, load sensor, etc. The measured raw material for the active material layer 14 is mixed in the mixing process S3. The mixing process S3 can be achieved by a mixing device (not shown). The raw material for the active material layer 14, which is made into a slurry by the mixing device, is coated onto the current collector 12 (see reference) in the coating process S4. Figure 2 The coating process S4 can be performed, for example, by a slit coater, gravure coater, die coater, commacoater, or other coating apparatus (not shown). In the drying process S5, the coated slurry-like active material layer 14 is dried. The drying process S5 can be performed, for example, by a drying apparatus that emits hot air or infrared radiation (not shown).

[0025] <Rolling process S6>

[0026] Rolling process S6 is a process of rolling the electrode sheet 10. Here, the substrate of the electrode sheet 10 is a metal foil. The electrode sheet 10 has a portion (coated portion 12b) where an active material layer 14 is formed and a portion (uncoated portion 12a) where no active material layer 14 is formed. The main purpose of rolling process S6 is to adjust the density of the active material layer 14 formed by coating to an appropriate level.

[0027] In the rolling process S6, the coating section 12b is rolled to achieve an appropriate density for the active material layer 14. If the coating section 12b is rolled, the current collector 12 of the substrate elongates in the coating section 12b, but in the uncoated section 12a, where the pressing pressure is not directly transmitted, the current collector 12 of the substrate is difficult to elongate. Therefore, if only the coating section 12b is pressed, the elongation of the current collector 12 may deviate between the coating section 12b and the uncoated section 12a. If the elongation deviation of the current collector 12 is large between the coating section 12b and the uncoated section 12a, it may cause wrinkles to form on the electrode sheet 10. The uncoated section 12a is cut into a predetermined shape in a subsequent process to form an electrode tab. At this time, if wrinkles form at the boundary portion 12d of the uncoated section 12a with the active material layer 14, the electrode tab may not be formed into an appropriate shape.

[0028] To prevent wrinkles from forming on the electrode sheet 10, the current collector 12 can be stretched on the uncoated portion 12a before or after rolling the coated portion 12b. One technique for stretching the current collector 12 on the uncoated portion 12a is to press the uncoated portion 12a with a rubber roller. This technique of pressing the uncoated portion 12a with a rubber roller is appropriately called EPS (Elasticity Powered Stretching). Furthermore, the device for pressing the uncoated portion 12a with a rubber roller can be appropriately called an EPS device.

[0029] However, the inventors discovered that even when the uncoated portion 12a is stretched by EPS before and after rolling, wrinkles still occur on the electrode sheet 10. These wrinkles are particularly noticeable at the boundary portion 12d of the uncoated portion 12a with the active material layer 14. Regarding this phenomenon, the inventors concluded that the reason for this is that the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is not properly stretched when the uncoated portion 12a is stretched by EPS.

[0030] That is, an active material layer 14 is formed in the coated portion 12b. The active material layer 14 is a layer coated with a metal oxide such as a lithium transition metal composite oxide. When the rubber roller of the EPS is pressed against the active material layer 14, it causes the active material layer 14 to peel off. From this point of view, in the EPS, the position of the rubber roller is set so that the rubber roller does not come into contact with the coated portion 12b. As a result, in the EPS, the boundary between the uncoated portion 12a and the coated portion 12b and its vicinity are difficult to stretch. In addition, there is a case where a protective layer containing inorganic fillers is formed at the boundary between the uncoated portion 12a and the coated portion 12b. When a protective layer is formed, when the rubber roller of the EPS is pressed, the elongation is sometimes inconsistent between the area where the protective layer is formed and the area where the protective layer is not formed.

[0031] Thus, when stretching the uncoated portion 12a by EPS, it is difficult to properly stretch the boundary portion 12d of the uncoated portion 12a with the active material layer 14. The inventors believe that as a result, residual deformation occurs in the boundary portion 12d, causing wrinkles on the electrode sheet.

[0032] Figure 4 This is a schematic diagram illustrating an example of the rolling process S6 presented herein. For example... Figure 4 As shown, the rolling process S6 includes a first pressing process S6a, a second pressing process S6b, and a stepped roller pressing process S6c.

[0033] The first pressing process S6a is the aforementioned EPS, which is the process of stretching the uncoated portion 12a of the electrode sheet 10. Figure 5 This is a schematic diagram of the first pressing device 104. Figure 5 In the diagram, the electrode sheet 10 and the pair of rubber rollers 30 and 35 are imaginarily separated. Figure 5 The cross-sections of the electrode sheet 10 and a pair of rubber rollers 30 and 35 are schematically shown in the diagram. The first pressing step S6a is performed by the first pressing device 104. Figure 5 As shown, the first pressing step S6a is a step in which the electrode sheet 10 is conveyed along a predetermined conveying path, and the uncoated portion 12a of the electrode sheet 10 is rolled using a pair of rubber rollers 30 and 35. Here, the pair of rubber rollers 30 and 35 roll the electrode sheet under tension. Although not particularly limited, the tension applied to the electrode sheet 10 before and after the pair of rubber rollers 30 and 35 is 150N to 250N, for example, it can be about 170N to 230N (about 200N in this embodiment).

[0034] Rubber rollers 30 and 35 can be roller components with elastomers 32 and 37 arranged on shafts 31 and 36. The elastomers 32 and 37 used in rubber rollers 30 and 35 can be elastic materials with the required Young's modulus. Examples of elastomers 32 and 37 include resins such as rubber or polyurethane. In the first pressing step S6a, the uncoated portion 12a is pressed by rubber rollers 30 and 35, and subjected to the reaction force of elastic deformation and compressive deformation of the rubber rollers. The pressed portion is pressed and stretched.

[0035] like Figure 4 As shown, the second pressing step S6b is a process of rolling the active material layer 14 (coating portion 12b) in the electrode sheet 10 after the first pressing step S6a. This process adjusts the active material layer 14 (coating portion 12b) to the required density. In the second pressing step S6b, as... Figure 4As shown, the electrode sheet 10 is held by a pair of rollers 41 and 42, and the active material layer 14 is compressed. At this time, at the part where the active material layer 14 is formed (coating part 12b), the current collector 12, which serves as the substrate, is pressed and stretched.

[0036] The stepped roller pressing process S6c is a process that applies tension by pressing the stepped roller 50 onto the uncoated portion 12a of the electrode sheet 10 after the first pressing process S6a. Figure 6 This is a schematic diagram of the stepped roller pressing process S6c.

[0037] <Stepped roller 50>

[0038] like Figure 6 As shown, the stepped roller 50 used in this process S6c has a step 51a at the portion 51 that contacts the boundary portion 12d of the active material layer 14 in the uncoated portion 12a. Furthermore, the diameter of the portion 52 in contact with the uncoated portion 12a is larger than the diameter of the portion 53 in contact with the active material layer 14. Figure 6 In the manner shown, the diameter of the portion 52 in contact with the uncoated portion 12a can be the same as the diameter of the portion 53 in contact with the active material layer 14.

[0039] Here, the boundary portion 12d between the uncoated portion 12a and the active material layer 14 can be the boundary between the active material layer 14 and the uncoated portion 12a of the electrode sheet 10, as well as the area near the boundary. The boundary portion 12d between the active material layer 14 and the uncoated portion 12a is defined as the portion where the current collector 12, as a substrate, is difficult to elongate during the first pressing step S6a of pressing and stretching the uncoated portion 12a and the second pressing step S6b of rolling the active material layer 14. The boundary portion 12d between the active material layer 14 and the uncoated portion 12a can be determined according to the specifications of the electrode sheet 10 and its manufacturing process. The width of the boundary portion 12d between the active material layer 14 and the uncoated portion 12a can be, for example, about 3 to 7 mm (e.g., about 5 mm). Figure 3 As shown, a protective layer 12c may also be formed at the boundary 12d between the active material layer 14 and the uncoated portion 12a.

[0040] like Figure 6 As shown, step 51a is provided at the portion 51 that contacts the boundary portion 12d of the active material layer 14 in the uncoated portion 12a. Figure 6In the illustrated manner, the height of step 51a can be set such that, when the electrode sheet 10 is wound around the stepped roller 50 and conveyed, the boundary portion 12d of the uncoated portion 12a with the active material layer 14 contacts the step 51a and is stretched. From this viewpoint, the height of step 51a also depends on the specifications of the electrode sheet 10 (e.g., the thickness of the current collector 12, the thickness of the active material layer 14 in the coated portion 12b, etc.). When the electrode sheet 10 is wound around the stepped roller 50 and conveyed, tension is applied to the electrode sheet 10. The tension applied to the electrode sheet 10 is 80N to 200N, for example, it can be about 100N to 160N (about 140N in this embodiment). In this embodiment, the tension applied to the uncoated portion 12a when the stepped roller 50 is pressed against it is set to be higher than that applied to the pair of rubber rollers 30, 35 (see reference 140N). Figure 4 The tension applied to the uncoated portion 12a before and after is small.

[0041] Here, the height h1 of step 51a is defined as the radial distance of the stepped roller 50 from the portion in contact with the coated portion 12b to the portion in contact with the uncoated portion 12a. The height h1 of step 51a is not particularly limited, and can be, for example, 0.25 mm or more and 1.50 mm or less. The height h1 of step 51a can also be 3.00 mm or less. Step 51a is formed by an inclined surface 51a1 that is similarly inclined relative to the axial direction of the stepped roller 50. The inclination angle of the inclined surface 51a1 relative to the axial direction of the stepped roller 50 can be, for example, 15 degrees or more and 45 degrees or less, preferably 30 degrees. Furthermore, the starting and ending points of the inclined surface 51a1 can be rounded, for example, preferably with a radius (R) of R=2.5.

[0042] <Method for manufacturing electrode sheets>

[0043] The method for manufacturing the electrode sheet 10 presented herein is as follows: Figure 4 As shown, the process is carried out in the order of the first pressing step S6a, the second pressing step S6b, and the stepped roller pressing step S6c.

[0044] In the first pressing step S6a, an EPS device that uses rubber rollers 30 and 35 to press the uncoated portion 12a can be used. In this case, the position and pressing force of the rubber rollers 30 and 35 can be adjusted in the EPS device so that the uncoated portion 12a is pressed by the rubber rollers 30 and 35. In addition, the position of the electrode sheet 10 conveyed toward the EPS device can be adjusted so that the position of the uncoated portion 12a is aligned with the rubber rollers 30 and 35 of the EPS device. In the stepped roller pressing step S6c, the position of the electrode sheet 10 can be adjusted relative to the stepped roller 50 so that the step 51a of the stepped roller 50 contacts the boundary portion 12d of the uncoated portion 12a with the active material layer 14. In this embodiment, the portion of the stepped roller 50 that contacts the uncoated portion 12a is thickened. Therefore, in the stepped roller pressing step S6c, the uncoated portion 12a, which has been stretched in the first pressing step S6a, is supported by the stepped roller 50.

[0045] <Electrode manufacturing apparatus 1>

[0046] like Figure 4 As shown, the electrode sheet manufacturing apparatus 1, which implements the method for manufacturing this electrode sheet, includes a rolling unit 100 for rolling the strip-shaped electrode sheet 10. The rolling unit 100 includes a conveying device 102, a first pressing device 104, a second pressing device 106, and a stepped roller pressing device 108. The rolling unit 100 may also include guide rollers 54-59 and tension rollers 61, 62. It should be noted that the positions of the guide rollers 54-59 and the tension rollers 61, 62 are not particularly limited. Figure 4 In the illustrated embodiment, the stepped roller pressing device 108 has one stepped roller 50, but it is not limited to this arrangement. Multiple stepped rollers 50 (not particularly limited, for example, three) may also be provided in the stepped roller pressing device 108. When multiple stepped rollers 50 are provided in the stepped roller pressing device 108, guide rollers may be provided between adjacent stepped rollers 50 on the conveying path W1. The number of stepped rollers 50 can be appropriately set according to the target elongation of the current collector 12, the quality of the finished electrode sheet 10, etc.

[0047] <Conveying device 102>

[0048] The conveying device 102 is a device for conveying the electrode sheet 10 along a predetermined conveying path W1. Although details of the conveying device 102 are omitted, it can be a device for conveying the electrode sheet 10 along the conveying path W1. Although not shown in the figure, the conveying device 102 may include: a mechanism for feeding the electrode sheet 10 along the conveying path W1, a guide roller for conveying the electrode sheet 10 along the conveying path W1, a tension adjustment mechanism for applying the required tension to the electrode sheet 10, and a mechanism for winding the electrode sheet 10 conveyed along the conveying path W1, etc.

[0049] <First pressing device 104>

[0050] The first pressing device 104 is a device disposed in the conveying path W1 and uses a pair of rubber rollers 30, 35 to press the uncoated portion 12a of the electrode sheet 10. The first pressing device 104 can be an EPS device that uses rubber rollers 30, 35 to press the uncoated portion 12a as described above. In the EPS device, the position and pressing force of the rubber rollers 30, 35 can be adjusted so that the uncoated portion 12a is pressed by the rubber rollers 30, 35. In addition, the first pressing device 104 can be equipped with a position adjustment device (not shown) that adjusts the position of the electrode sheet 10 conveyed toward the EPS device so that the position of the uncoated portion 12a is aligned with the rubber rollers 30, 35 of the EPS device.

[0051] like Figure 5 As shown, a pair of rubber rollers 30 and 35 includes an upper roller 30 and a lower roller 35. The rotation axes of the upper roller 30 and the lower roller 35 are substantially parallel. One of the upper roller 30 and the lower roller 35 can be configured to be driven relative to the other. In this embodiment, the upper roller 30 is pressed against the lower roller 35. Thus, the pair of rubber rollers 30 and 35 roll the electrode sheet 10.

[0052] <Lower roller 35>

[0053] The lower roller 35 is a cylindrical roller disposed below the electrode sheet 10. The lower roller 35 is longer in the axial direction than the width of the electrode sheet 10. The end of the lower roller 35 protrudes outward relative to the electrode sheet 10. The lower roller 35 contacts the uncoated portion 12a of the current collector 12 and the active material layer 14, supporting the entire surface of the electrode sheet 10 from below in the width direction. It should be noted that the lower roller 35 does not necessarily need to support the entire electrode sheet 10; it may be configured to support only the uncoated portion 12a of the electrode sheet 10.

[0054] The lower roller 35 includes a shaft 36 and an elastic body 37. In this embodiment, the shaft 36 is generally cylindrical and has a generally fixed radius along its length. The elastic body 37 is wound around the shaft 36. The length of the elastic body 37 is approximately the same as the length of the shaft 36. Although not particularly limited, the thickness of the elastic body 37 can be set to a range of 5 mm or more and 20 mm or less (for example, 8 mm or more and 16 mm or less). The elastic body 37 is generally cylindrical and has a generally fixed thickness in both the circumferential and length directions. Therefore, the radius of the lower roller 35 is generally fixed along its length. An upper roller 30 is provided above the lower roller 35.

[0055] <Upper Roller 30>

[0056] The upper roller 30 is a disc-shaped roller disposed above the electrode sheet 10. The upper roller 30 is positioned to press the uncoated portion 12a of the electrode sheet 10. The inner end portion 30d of the upper roller 30 can be disposed near the boundary between the uncoated portion 12a and the coated portion 12b. In this embodiment, the inner end portion 30d of the upper roller 30 is disposed at a position corresponding to the end of the active material layer 14. The inner end portion 30d of the upper roller 30 is set to slightly overlap with the coated portion 12b. The upper roller 30 is configured to press the uncoated portion 12a of the electrode sheet 10. The width (axial dimension) of the upper roller 30 is larger than the width of the uncoated portion 12a of the electrode sheet 10. The outer end portion 30e of the upper roller 30 protrudes outwards compared to the end of the uncoated portion 12a. The width of the upper roller 30 is not particularly limited and can be set to a size that does not protrude outwards compared to the lower roller 35.

[0057] The upper roller 30 includes a shaft 31 and an elastic body 32. In this embodiment, the shaft 31 is generally disk-shaped and has a generally fixed radius along its length. The elastic body 32 is wound around the shaft 31. The length of the elastic body 32 is approximately the same as the length of the shaft 31. The elastic body 32 is generally cylindrical and has a generally fixed thickness in both the circumferential and length directions, except for the ends 33. The corners of the two ends 33 are formed with a so-called right angle. The corners of the ends 33 are continuously inclined in the circumferential direction. It should be noted that the shape of the ends 33 is not particularly limited, and it can also be a shape with rounded corners continuously formed in the circumferential direction. The ends 33 may also not be chamfered, and the corners may be approximately right angles. In this embodiment, the two ends 33 are each provided with an axial dimension of C1 (refer to...). Figure 5 The right angle is a chamfer. The angle of the chamfer can be 30 degrees to 60 degrees. In this embodiment, the angle of the chamfer is approximately 45 degrees.

[0058] The upper roller 30 has a first portion 30a, a second portion 30b, and a third portion 30c sequentially from the inner end 30d to the outer end 30e. The first portion 30a is the part that presses the boundary portion 12d between the uncoated portion 12a and the active material layer 14. The second portion 30b and the third portion 30c are the parts that press the outer side of the boundary portion 12d. Therefore, the first portion 30a is positioned overlapping the boundary portion 12d of the electrode sheet 10. The second portion 30b and the third portion 30c are positioned further outward than the boundary portion 12d of the electrode sheet 10. The shaft 31 and the elastic body 32 each have portions corresponding to the first portion 30a, the second portion 30b, and the third portion 30c of the upper roller 30.

[0059] Shaft 31 includes a first portion 31a, a second portion 31b, and a third portion 31c. The second portion 31b is continuous with the outer end of the first portion 31a in the axial direction. The third portion 31c is continuous with the outer end of the second portion 31b in the axial direction. Elastic body 32 includes a first portion 32a, a second portion 32b, and a third portion 32c. The second portion 32b is continuous with the outer end of the first portion 32a in the axial direction. The third portion 32c is continuous with the outer end of the second portion 32b in the axial direction. The first portion 32a, the second portion 32b, and the third portion 32c of elastic body 32 are wound relative to the first portion 31a, the second portion 31b, and the third portion 31c of shaft 31, respectively. The first portion 31a, the second portion 31b, the third portion 31c of shaft 31 and the first portion 32a, the second portion 32b, and the third portion 32c of elastic body 32 correspond to the first portion 30a, the second portion 30b, and the third portion 30c of upper roller 30, respectively.

[0060] The shaft 31 has different diameters along its length. In this embodiment, the diameter of the first portion 31a is approximately fixed axially. The diameter of the second portion 31b gradually decreases outwards axially. In other words, the second portion 31b is inclined in such a way that its diameter decreases outwards axially. The diameter of the third portion 31c is approximately fixed axially. Therefore, the diameter of the first portion 31a is larger than the diameters of the second portion 31b and the third portion 31c.

[0061] The elastomer 32 has a different thickness along its length. In this embodiment, the thickness of the first portion 32a is approximately fixed in the axial direction. The thickness of the first portion 32a can be the same as the thickness of the elastomer 37 of the lower roller 35. The thickness of the second portion 32b gradually increases towards the axially outward side. In other words, the inner circumferential surface of the second portion 32b is inclined in a manner that increases towards the axially outward side. In this embodiment, the inner circumferential surface of the second portion 32b increases towards the axially outward side. The thickness of the third portion 32c is approximately fixed in the axial direction. Therefore, the thickness of the first portion 32a is thinner than the thicknesses of the second portion 32b and the third portion 32c. Since the thickness of the elastomer 32 in the second portion 32b gradually increases towards the axially outward side, it is easy to adjust the elongation of the uncoated portion 12a in the width direction.

[0062] Although not specifically limited, the thickness of the elastomer 32 can be set to a level of 5 mm or more and 20 mm or less at any part of the first part 32a to the third part 32c (for example, a level of 8 mm or more and 16 mm or less).

[0063] In the second part 32b, the elastomer 32 may also be inclined at an angle of 10 degrees or more and 25 degrees or less (e.g., 12 degrees or more and 20 degrees or less) such that it thickens from the end of the first part 32a toward the axially outward. Similarly, the second part 31b of the shaft 31 is also inclined at an angle corresponding to the second part 32b of the elastomer 32 such that it tapers from the end of the first part 31a toward the axially outward. It should be noted that the angle of inclination of the elastomer 32 in the second part 32b is not particularly limited.

[0064] The thickness of the elastomer 32 in the third part 32c can be set to be more than 1.3 times and less than 2.0 times the thickness of the elastomer 32 in the first part 32a. The thickness of the third part 32c of the elastomer 32 can also be set to be more than 1.4 times and less than 1.8 times the thickness of the first part 32a.

[0065] Here, the length Y1 of the first portion 30a is greater than the width C1+X1 from the inner end 30d of the upper roller 30 to the outer end of the boundary portion 12d (protective layer 12c). Therefore, the first portion 30a covers the boundary portion 12d. The inner end of the first portion 30a reaches a position closer to the inner end of the boundary portion 12d, and the outer end of the first portion 30a reaches a position further outward than the outer end of the boundary portion 12d. In other words, the first portion 30a is set to cover the boundary portion 12d in both position and size. Therefore, the boundary portion 12d is pressurized by the first portion 30a.

[0066] The length Y2 of the second portion 30b is smaller than the width X2 of the uncoated portion 12a. Here, when a protective layer 12c is formed on the electrode sheet 10, the width X2 of the uncoated portion 12a is the width from the outer end of the protective layer 12c to the outer end of the electrode sheet 10. When no protective layer 12c is formed on the electrode sheet 10, the width X2 of the uncoated portion 12a is the width from the outer end of the active material layer 14 to the outer end of the electrode sheet 10. The second portion 30b overlaps with a portion of the uncoated portion 12a. The position and size of the second portion 30b are set to be contained within the width X2 of the uncoated portion 12a. Therefore, the uncoated portion 12a is pressed by the first portion 30a, the second portion 30b, and the third portion 30c.

[0067] The combined length Y1+Y2 of the first portion 30a and the second portion 30b is at least 0.6 times and less than 0.85 times (for example, at least 0.65 times and less than 0.8 times) the width C1+X1+X2 of the overlap between the electrode sheet 10 and the upper roller 30. In this embodiment, the inner end portion 30d of the upper roller 30 is positioned to overlap with the coating portion 12b. Therefore, the width of the overlap between the electrode sheet 10 and the upper roller 30 is wider than the width of the uncoated portion 12a, including the boundary portion 12d.

[0068] In this embodiment, the length Y3 by which the upper roller 30 is pressed against the lower roller 35 is at least 1.2 times and less than 2.1 times (for example, at least 1.6 times and less than 2.0 times) the width of the unformed portion 12a pressed by the pair of rubber rollers 30, 35 (the width of the unformed portion 12a pressed by the pair of rubber rollers 30, 35) X1 + X2. Therefore, the outer end of the unformed portion 12a is pressed from approximately the center of the upper roller 30 by the outer portion.

[0069] Figure 7 This is a schematic diagram showing the elongation of the electrode sheet 10 being rolled during the first pressing process S6a. Figure 7 The diagram schematically shows a top view of the electrode sheet 10. The elongation of the electrode sheet 10 is indicated by arrows; the greater the elongation, the longer the arrow. In the top view of the electrode sheet 10, the position pressed by the upper roller 30 is indicated by a double-dotted line. It should be noted that... Figure 7 The diagram in the image is merely a hypothetical representation of the elongation of electrode 10; the actual relationship between the elongations of electrode 10 in different sections may not be as detailed. Figure 7 As shown.

[0070] In the inventor's experiments, such as Figure 7 As shown, in portions of the upper roller 30 with uniform thickness, the elongation of the uncoated portion 12a is greater closer to the center of that portion (solid arrow). Furthermore, the portion of the uncoated portion 12a that is rolled over where the elastomer 32 of the upper roller 30 is thinner (e.g., the first portion 30a) is greater (dashed arrow). It should be noted that, as described above, the current collector 12 is difficult to elongate near the boundary portion 12d of the active material layer 14 (or, the portion where the protective layer 12c is formed). Additionally, there are portions of the protective layer 12c that are not pressed by the upper roller 30. Furthermore, in this embodiment, since the end 33 is chamfered, only a portion of the boundary portion 12d is rolled over. Therefore, the elongation of the boundary portion 12d of the uncoated portion 12a is minimal.

[0071] In the above embodiment, the combined length Y1+Y2 of the first portion 30a and the second portion 30b is set to be at least 0.6 times the width C1+X1+X2 of the overlap between the electrode sheet 10 and the upper roller 30. Therefore, the outer end of the uncoated portion 12a can be pressed by the third portion 30c, which has the same thickness as the elastomer 32. Furthermore, the central portion of the uncoated portion 12a can be pressed by the second portion 30b, which has a thinner thickness than the elastomer 32. The portion pressed by the third portion 30c is adjusted to an appropriate range, and the elongation of the central portion of the uncoated portion 12a can be easily adjusted to the same degree as the outer end.

[0072] In the above embodiment, the combined length Y1+Y2 of the first portion 30a and the second portion 30b is set to be less than 0.85 times the width C1+X1+X2 of the overlap between the electrode sheet 10 and the upper roller 30. Therefore, the thickness of the elastomer 32 of the third portion 30c, which presses the outer end of the uncoated portion 12a, is less likely to become excessive. As a result, it is easier to maintain the elongation of the outer end of the uncoated portion 12a pressed by the third portion 30c.

[0073] In the above embodiment, the length Y3 by which the upper roller 30 is pressed against the lower roller 35 is more than 1.2 times and less than 2.1 times the width X1+X2 of the uncoated portion 12a pressed by the pair of rubber rollers 30, 35. Therefore, the outer end of the uncoated portion 12a is easily pressed near the center of the third portion 30c of the upper roller 30. Since the outer end of the uncoated portion 12a is pressed near the center of the third portion 30c where the elastomer 32 is thick, elongation is easily maintained. As a result, the elongation of the outer end and the center of the uncoated portion 12a tends to be the same.

[0074] In the above embodiment, in the second part 32b, the elastomer 32 is inclined at an angle of 10 degrees or more, thickening from the end of the first part 32a toward the axially outward direction. As a result, the thickness difference between the first part 30a and the third part 30c may increase. Consequently, in the first pressing step S6a, the elongation near the boundary portion 12d of the uncoated portion 12a pressed by the first part 30a is relatively easy to increase. Therefore, the area near the boundary portion 12d of the uncoated portion 12a can be locally stretched in the stepped roller pressing step S6c. As a result, the uncoated portion 12a of the electrode sheet 10 as a whole can be easily stretched uniformly.

[0075] In the above embodiment, in the second portion 32b, the elastomer 32 is inclined at an angle of less than 25 degrees, thickening from the end of the first portion 32a toward the axially outward direction. Therefore, in the electrode sheet 10, the difference in stress distribution near the portion pressed by the second portion 30b is less likely to increase. As a result, damage to the electrode sheet 10 is easily suppressed.

[0076] In the above embodiment, the thickness of the elastomer 32 in the third part 32c is set to be at least 1.3 times the thickness of the elastomer 32 in the first part 32a. Therefore, the elongation difference between the boundary portion 12d of the uncoated portion 12a and the outer end of the uncoated portion 12a is less likely to become excessive. Consequently, when stretching the boundary portion 12d of the uncoated portion 12a in the stepped roller pressing process S6c, the tension applied to the boundary portion 12d of the uncoated portion 12a can be relatively small. As a result, damage to the electrode sheet 10 in the stepped roller pressing process S6c is easily suppressed.

[0077] In the above embodiment, the thickness of the elastomer 32 in the third part 32c is set to be less than 2.0 times the thickness of the elastomer 32 in the first part 32a. This makes it easy to appropriately suppress the elongation of the boundary portion 12d of the uncoated portion 12a. Therefore, in the second pressing step S6b, the elongation of the boundary portion 12d near the active material layer 14 of the electrode sheet 10 can be appropriately suppressed. As a result, when the electrode sheet 10 is held by a pair of rollers 41, 42 in the second pressing step S6b, the boundary portion 12d is less likely to swing up and down. By suppressing the swing of the boundary portion 12d, concerns about damage to the rollers 41, 42 and breakage of the boundary portion 12d caused by the rollers 41, 42 biting into the boundary portion 12d can be reduced.

[0078] like Figure 4 As shown, the electrode sheet 10, after being rolled by the first pressing device 104, is hung on the tension roller 61 and guide rollers 54 and 55, and is conveyed to the second pressing device 106. The tension roller 61 is configured to adjust the tension applied to the electrode sheet 10 between the first pressing device 104 and the second pressing device 106. The tension applied to the electrode sheet 10 between the first pressing device 104 and the second pressing device 106 is controlled by the control device 110. The control device 110 is configured to control the tension applied to the electrode sheet 10 at each location along the conveying path W1.

[0079] <Second pressing device 106>

[0080] The second pressing device 106 is disposed downstream of the first pressing device 104 on the conveying path W1. The second pressing device 106 is a device for rolling the active material layer 14. It includes a pair of rollers (rolling rollers) 41 and 42. The pair of rollers 41 and 42 are generally cylindrical rollers that extend along the width direction of the active material layer 14 of the electrode sheet 10. In the second pressing device 106, the pair of rollers 41 and 42 are configured to be rotated by a drive device (not shown) that drives the rollers 41 and 42. The pair of rollers 41 and 42 are rotated while in contact with each other, and the electrode sheet 10 passes between them. At this time, the coating portion 12b of the electrode sheet 10 is stretched along the conveying direction.

[0081] The electrode sheet 10, after being pressed by the second pressing device 10, is conveyed to the stepped roller pressing device 108. The electrode sheet 10 can also be hung on the guide roller and conveyed to the stepped roller pressing device 108.

[0082] <Stepped roller pressing device 108>

[0083] The stepped roller pressing device 108 is a device disposed on the conveying path W1 and pressing the stepped roller 50 onto the electrode sheet 10. A specific example of the shape of the stepped roller 50 is described above. In the stepped roller pressing device 108, as... Figure 6 As shown, a step 51a is provided corresponding to the boundary portion 12d of the uncoated portion 12a of the electrode sheet 10 with the active material layer 14. Furthermore, the diameter of the portion 52 in contact with the uncoated portion 12a is larger than the diameter of the portion 53 in contact with the active material layer 14. In the stepped roller pressing device 108, the position of the electrode sheet 10 is adjusted and it is conveyed so that the position of the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is aligned with the step 51a of the stepped roller 50. Therefore, a position adjustment device (not shown) for adjusting the position of the electrode sheet 10 can be provided before the stepped roller 50.

[0084] Thus, in the stepped roller pressing device 108, the portion 51 of the stepped roller 50, where the step 51a is provided, is pressed against the boundary portion 12d of the uncoated portion 12a of the electrode sheet 10, which is adjacent to the active material layer 14, and is conveyed. Here, the stepped roller pressing device 108 is positioned downstream of the first pressing device 104 (first pressing process S6a) for stretching the uncoated portion 12a and the second pressing device 106 (second pressing process S6b) for stretching the coated portion 12b. After the electrode sheet 10 is stretched in the uncoated portion 12a and the coated portion 12b, the boundary portion 12d of the uncoated portion 12a, which is adjacent to the active material layer 14, is stretched by the step 51a of the stepped roller 50. Furthermore, in the stepped roller 50, the diameter of the portion 52 that contacts the uncoated portion 12a is larger than the diameter of the portion 53 that contacts the active material layer 14.

[0085] Therefore, the uncoated portion 12a and the active material layer 14, which have been stretched by the first pressing device 104, are properly supported on the stepped roller 50, and the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is pressed against the step 51a of the stepped roller 50 and corrected. Therefore, when the electrode sheet 10 is pressed against the stepped roller 50, the electrode sheet 10 is less likely to break.

[0086] A tension roller 62 and guide rollers 58 and 59 are provided on the downstream side of the stepped roller pressing device 108. The tension roller 62 is configured to adjust the tension applied to the electrode sheet 10 on the downstream side of the second pressing device 106. The tension applied to the electrode sheet 10 on the downstream side of the second pressing device 106 is controlled by the control device 110.

[0087] Figure 8 This is a schematic diagram showing the elongation of the current collector 12. Figure 8 In the diagram, solid arrows indicate the elongation of the electrode sheet 10 in each of the first pressing process S6a, the second pressing process S6b, and the stepped roller pressing process S6c. Figure 8 In the diagram, dashed arrows indicate the amount of stretching of electrode sheet 10 during previous processes. It should be noted that... Figure 8 The diagram in the image is merely a hypothetical representation of the elongation of electrode 10; the actual relationship between the elongations of electrode 10 in different sections may not be as detailed. Figure 8 As shown. Figure 8 As shown, the electrode sheet 10 first stretches the uncoated portion 12a through a first pressing process S6a. Then, through a second pressing process S6b, the coated portion 12b is further stretched. Next, through a stepped roller pressing process S6c, the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is stretched. In this case, the uncoated portion 12a is stretched through the first pressing process S6a, and the coated portion 12b is stretched through the second pressing process S6b. Then, the boundary portion 12d of the uncoated portion 12a is partially stretched through the stepped roller pressing process S6c. Therefore, wrinkles caused by the difference in elongation between the boundary portion 12d of the uncoated portion 12a with the active material layer 14 and the current collector 12 in other portions 12a, 12b can be suppressed, and wrinkles can be suppressed as a whole in the electrode sheet 10. It should be noted that, in the uncoated portion 12a, the portion near the protective layer 12c (boundary portion 12d) exhibits insufficient elongation during the first pressing step S6a compared to the portion extending from the center to the outside. In this embodiment, a portion of the thinner portion (first portion 30a) of the elastomer 32 in the rubber roller 30 is adjusted to overlap with the portion near the protective layer 12c (see reference). Figure 5Therefore, in the stepped roller pressing process S6c, the uncoated portion 12a near the aforementioned protective layer 12c is also auxiliaryly stretched. As a result, wrinkles are more easily suppressed as a whole as the electrode sheet 10.

[0088] Here, in the process of stretching the uncoated portion 12a (first pressing step S6a), as described above, it can be performed, for example, by EPS. As described above, in EPS, it is difficult to stretch the current collector 12 in the uncoated portion 12a at the boundary portion 12d with the active material layer 14. In the electrode sheet manufacturing method and electrode sheet manufacturing apparatus 1 presented here, the current collector 12 in the uncoated portion 12a at the boundary portion 12d with the active material layer 14 is stretched by a stepped roller 50.

[0089] Since the boundary portion 12d is stretched by being pressed against the step 51a of the stepped roller 50, the boundary portion 12d is appropriately stretched even when a protective layer 12c is present at the boundary portion 12d with the active material layer 14 in the uncoated portion 12a.

[0090] According to the inventors' experiments, when stretching the uncoated portion using an EPS device, the boundary portion (or the portion with the protective layer) is also difficult to elongate. Here, the electrode sheet manufacturing apparatus 1 includes a conveying device 102, a first pressing device 104, a second pressing device 106, and a stepped roller pressing device 108. The first pressing device 104 is disposed on the conveying path W1. The first pressing device 104 is a device that uses a pair of rubber rollers 30, 35 to roll the unformed portion 12a in the electrode sheet 10. The second pressing device 106 is disposed on the conveying path W1 downstream of the first pressing device 104 and rolls the active material layer 14. The stepped roller pressing device 108 is disposed on the conveying path W1 downstream of the second pressing device 106 and applies tension by pressing the stepped roller 50 against the unformed portion 12a of the electrode sheet 10. The upper roller 30 of the pair of rubber rollers 30, 35 includes a shaft 31 and an elastic body 32 wound on the shaft 31. In the upper roller 30, the diameter of the shaft 31 of the portion pressing the boundary portion 12d between the unformed portion 12a and the active material layer 14 (the first portion 30a in this embodiment) is larger than the diameter of the shaft 31 of the portions pressing the outer side of the boundary portion 12d (the second portion 30b and the third portion 30c in this embodiment). The thickness of the elastomer 32 in the portion pressing the boundary portion 12d is thinner than the thickness of the elastomer 32 in the portion pressing the outer side of the boundary portion 12d.

[0091] According to the electrode sheet manufacturing apparatus 1, at the location where the boundary portion 12d is pressed, the diameter of the shaft 31 increases and the thickness of the elastomer 32 decreases. Therefore, in the first pressing device 104, the boundary portion 12d, which is difficult to stretch in a conventional EPS device, can be easily stretched along the conveying direction. Furthermore, the active material layer 14 is pressed by the second pressing device 106, stretching the forming portion 12b. Then, the boundary portion 12d is further stretched by the stepped roller pressing device 108. As a result, the overall elongation of the current collector 12 easily becomes uniform. Consequently, the tabs can be properly processed in subsequent processes. Additionally, damage to the electrode sheet 10 that may occur due to uneven elongation of the current collector 12 in the width direction is easily prevented.

[0092] It should be noted that while the upper roller 30 has the aforementioned structure, it is not limited to this configuration. The structure of the upper roller 30 described above can also be provided on the lower roller 35. Furthermore, the structure of the upper roller 30 described above can be provided on both the upper roller 30 and the lower roller 35. Alternatively, the structure of the upper roller 30 described above can be provided on the lower roller 35, and the structure of the lower roller 35 can be provided on the upper roller. In other words, the upper roller 30 and the lower roller 35 can also be configured to rotate vertically.

[0093] Furthermore, in the inventors' view, to stretch the boundary portion, it is necessary to increase the pressing pressure of the EPS device or increase the tension applied to the electrode sheets before and after the EPS device. However, when the pressing pressure of the EPS device is increased, the friction of the pair of rubber rollers constituting the EPS device increases, and the deformation becomes larger. As a result, it is easy to apply heat to the pair of rubber rollers, and the rubber rollers are prone to deterioration. In addition, in the inventors' view, in order to locally stretch the boundary portion, when the stepped roller is pressed against the uncoated portion, electrode sheet breakage is likely to occur.

[0094] Here, the tension applied to the uncoated portion 12a when the stepped roller 50 is pressed against it is set to a lower tension than the tension applied to the uncoated portion 12a before and after the pair of rubber rollers 30, 35. The tension applied to the electrode sheet 10 before and after the pair of rubber rollers 30, 35 constituting the first pressing device 104 (EPS device) is set to a relatively high value. As a result, the boundary portion 12d of the uncoated portion 12a is stretched. Since the boundary portion 12d of the uncoated portion 12a is stretched, even if the tension applied to the uncoated portion 12a when the stepped roller 50 is pressed against it is reduced, the elongation of the boundary portion 12d can be easily and appropriately adjusted. In addition, by reducing the tension applied to the uncoated portion 12a when the stepped roller 50 is pressed against it, the uncoated portion 12a is less likely to be damaged, and the possibility of the electrode sheet 10 breaking can be reduced.

[0095] The technology disclosed herein has been described above in various ways. Unless otherwise specified, the embodiments listed herein are not intended to limit the invention. Furthermore, the technology disclosed herein is capable of various modifications; various components and processes mentioned herein can be appropriately omitted or combined without causing particular problems. This specification also includes the disclosures described below.

[0096] Item 1:

[0097] An electrode sheet manufacturing apparatus manufactures an electrode sheet having a current collector, an unformed portion, and an active material layer. The current collector is composed of a strip of metal foil. The unformed portion is positioned along its length at a predetermined position in the width direction of the current collector. The active material layer is formed in the current collector in the portion excluding the unformed portion. The electrode sheet manufacturing apparatus comprises:

[0098] A conveying device that conveys the electrode sheet along a predetermined conveying path;

[0099] A first pressing device is disposed in the conveying path and uses a pair of rubber rollers to press the unformed portion in the electrode sheet.

[0100] A second pressing device, disposed downstream of the first pressing device on the conveying path, rolls the active material layer; and

[0101] A stepped roller pressing device, disposed downstream of the second pressing device on the conveying path, applies tension by pressing the stepped roller against the unformed portion of the electrode sheet.

[0102] The stepped roller has a step at the portion that contacts the boundary of the active material layer in the unformed portion, wherein the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer.

[0103] At least one of the pair of rubber rollers has a shaft and an elastic body wound around the shaft.

[0104] In the at least one rubber roller,

[0105] The diameter of the shaft of the portion pressing the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft of the portion pressing the outer side of the boundary portion.

[0106] The thickness of the elastomer at the portion where the boundary portion is pressed is thinner than the thickness of the elastomer at the portion where the outer side of the boundary portion is pressed.

[0107] Item 2:

[0108] In the electrode sheet manufacturing apparatus described in item 1, the tension applied to the unformed portion when the stepped roller is pressed against the unformed portion is smaller than the tension applied to the unformed portion before and after the pair of rubber rollers.

[0109] Item 3:

[0110] In the electrode sheet manufacturing apparatus described in item 1 or 2

[0111] The at least one rubber roller comprises:

[0112] The first part, the first part presses on the boundary portion; and

[0113] The second and third parts press on the outer side of the boundary portion.

[0114] In the first part, the thickness of the elastomer is fixed.

[0115] In the second part, the elastomer gradually thickens from the end of the first part toward the axially outward side.

[0116] In the third part, the thickness of the elastomer is fixed from the end of the second part toward the axially outward side.

[0117] Item 4:

[0118] In the electrode sheet manufacturing apparatus described in item 3

[0119] The at least one rubber roller is positioned at the inner end corresponding to the end of the active material layer.

[0120] The first part covers the boundary portion.

[0121] The length of the second part is smaller than the width of the unformed part.

[0122] The combined length of the first portion and the second portion is more than 0.6 times and less than 0.85 times the width of the overlap between the electrode sheet and the at least one rubber roller.

[0123] Item 5:

[0124] In the electrode sheet manufacturing apparatus described in item 3 or 4, the length by which the at least one rubber roller is pressed against at least one of the electrode sheet and another rubber roller is more than 1.2 times and less than 2.1 times the width by which the unformed portion is pressed by the pair of rubber rollers.

[0125] Item 6:

[0126] In the electrode sheet manufacturing apparatus described in item 5, in the second part, the elastomer is inclined at an angle of 10 degrees or more and 25 degrees or less, such that it thickens from the end of the first part toward the axially outward direction.

[0127] Item 7:

[0128] In the electrode sheet manufacturing apparatus described in item 5 or 6, the thickness of the elastomer in the third part is more than 1.3 times and less than 2.0 times the thickness of the elastomer in the first part.

[0129] Item 8:

[0130] A method for manufacturing an electrode sheet, the electrode sheet having a current collector, an unformed portion, and an active material layer, the current collector being composed of a strip of metal foil, the unformed portion being positioned along its length at a predetermined position in the width direction of the current collector, and the active material layer being formed in the current collector in areas other than the unformed portion, wherein the method for manufacturing the electrode sheet includes:

[0131] In the first pressing step, the electrode sheet is conveyed along a predetermined conveying path, and the unformed portion of the electrode sheet is rolled using a pair of rubber rollers.

[0132] The second pressing step, following the first pressing step, involves rolling the active material layer; and

[0133] In the stepped roller pressing process, following the second pressing process, tension is applied by pressing the stepped roller against the unformed portion of the electrode sheet.

[0134] The stepped roller has a step at the portion that contacts the boundary of the active material layer in the unformed portion, wherein the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer.

[0135] At least one of the pair of rubber rollers has a shaft and an elastic body wound around the shaft.

[0136] In the at least one rubber roller,

[0137] The diameter of the shaft of the portion pressing the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft of the portion pressing the outer side of the boundary portion.

[0138] The thickness of the elastomer at the portion where the boundary portion is pressed is thinner than the thickness of the elastomer at the portion where the outer side of the boundary portion is pressed.

[0139] Item 9:

[0140] In the method for manufacturing the electrode sheet described in item 8, during the stepped roller pressing process, the tension applied to the unformed portion when the stepped roller is pressed onto the unformed portion is smaller than the tension applied to the unformed portion before and after the pair of rubber rollers.

[0141] Item 10:

[0142] In the method for manufacturing the electrode sheet described in item 8 or 9,

[0143] The at least one rubber roller comprises:

[0144] The first part, the first part presses on the boundary portion; and

[0145] The second and third parts press on the outer side of the boundary portion.

[0146] In the first part, the thickness of the elastomer is fixed.

[0147] In the second part, the elastomer gradually thickens from the end of the first part toward the axially outward side.

[0148] In the third part, the thickness of the elastomer is fixed from the end of the second part toward the axially outward side.

[0149] Item 11:

[0150] In the method for manufacturing the electrode sheet described in item 10,

[0151] The at least one rubber roller is positioned at the inner end corresponding to the end of the active material layer.

[0152] The first part covers the boundary portion.

[0153] The length of the second part is smaller than the width of the unformed part.

[0154] The combined length of the first portion and the second portion is more than 0.6 times and less than 0.85 times the width of the overlap between the electrode sheet and the at least one rubber roller.

[0155] Item 12:

[0156] In the method of manufacturing the electrode sheet according to item 10 or 11, the length by which the at least one rubber roller is pressed against at least one of the electrode sheet and another rubber roller is more than 1.2 times and less than 2.1 times the width of the unformed portion pressed by the pair of rubber rollers.

[0157] Item 13:

[0158] In the method of manufacturing the electrode sheet described in item 12, in the second part, the elastomer is inclined at an angle of 10 degrees or more and 25 degrees or less, such that it thickens from the end of the first part toward the axially outward direction.

[0159] Item 14:

[0160] In the method of manufacturing the electrode sheet according to item 12 or 13, the thickness of the elastomer in the third part is more than 1.3 times and less than 2.0 times the thickness of the elastomer in the first part.

Claims

1. An electrode sheet manufacturing apparatus for manufacturing an electrode sheet having a current collector, an unformed portion, and an active material layer, wherein the current collector is composed of a strip of metal foil, the unformed portion is disposed at a predetermined position in the width direction of the current collector along its length direction, and the active material layer is formed in the current collector in the portion excluding the unformed portion, wherein... The electrode sheet manufacturing apparatus includes: A conveying device that conveys the electrode sheet along a predetermined conveying path; A first pressing device is disposed in the conveying path and uses a pair of rubber rollers to press the unformed portion in the electrode sheet. A second pressing device, disposed downstream of the first pressing device on the conveying path, rolls the active material layer; and A stepped roller pressing device, disposed downstream of the second pressing device on the conveying path, applies tension by pressing the stepped roller against the unformed portion of the electrode sheet. The stepped roller has a step at the portion that contacts the boundary of the active material layer in the unformed portion, wherein the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer. At least one of the pair of rubber rollers has a shaft and an elastic body wound around the shaft. In the at least one rubber roller, The diameter of the shaft of the portion pressing the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft of the portion pressing the outer side of the boundary portion. The thickness of the elastomer at the portion where the boundary portion is pressed is thinner than the thickness of the elastomer at the portion where the outer side of the boundary portion is pressed.

2. The electrode sheet manufacturing apparatus as described in claim 1, wherein, The tension applied to the unformed portion when the stepped roller is pressed against it is less than the tension applied to the unformed portion before and after the pair of rubber rollers.

3. The electrode sheet manufacturing apparatus as described in claim 1 or 2, wherein, The at least one rubber roller comprises: The first part, the first part presses on the boundary portion; and The second and third parts press on the outer side of the boundary portion. In the first part, the thickness of the elastomer is fixed. In the second part, the elastomer gradually thickens from the end of the first part toward the axially outward side. In the third part, the thickness of the elastomer is fixed from the end of the second part toward the axially outward side.

4. The electrode sheet manufacturing apparatus as described in claim 3, wherein, The at least one rubber roller is positioned at the inner end corresponding to the end of the active material layer. The first part covers the boundary portion. The length of the second part is smaller than the width of the unformed part. The combined length of the first portion and the second portion is more than 0.6 times and less than 0.85 times the width of the overlap between the electrode sheet and the at least one rubber roller.

5. The electrode sheet manufacturing apparatus as described in claim 3, wherein, The length by which at least one rubber roller is pressed against at least one of the electrode sheet and the other rubber roller is more than 1.2 times and less than 2.1 times the width of the unformed portion pressed by the pair of rubber rollers.

6. The electrode sheet manufacturing apparatus as described in claim 5, wherein, In the second part, the elastomer is inclined at an angle of more than 10 degrees and less than 25 degrees, such that it thickens from the end of the first part toward the axially outward.

7. The electrode sheet manufacturing apparatus as described in claim 5, wherein, The thickness of the elastomer in the third part is more than 1.3 times and less than 2.0 times the thickness of the elastomer in the first part.

8. A method for manufacturing an electrode sheet, the electrode sheet having a current collector, an unformed portion, and an active material layer, the current collector being composed of a strip of metal foil, the unformed portion being disposed at a predetermined position in the width direction of the current collector along its length direction, and the active material layer being formed in the current collector in portions other than the unformed portion, wherein... The method for manufacturing the electrode sheet includes: In the first pressing step, the electrode sheet is conveyed along a predetermined conveying path, and the unformed portion of the electrode sheet is rolled using a pair of rubber rollers. The second pressing step, following the first pressing step, involves rolling the active material layer; and In the stepped roller pressing process, following the second pressing process, tension is applied by pressing the stepped roller against the unformed portion of the electrode sheet. The stepped roller has a step at the portion that contacts the boundary of the active material layer in the unformed portion, wherein the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer. At least one of the pair of rubber rollers has a shaft and an elastic body wound around the shaft. In the at least one rubber roller, The diameter of the shaft of the portion pressing the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft of the portion pressing the outer side of the boundary portion. The thickness of the elastomer at the portion where the boundary portion is pressed is thinner than the thickness of the elastomer at the portion where the outer side of the boundary portion is pressed.

9. The method for manufacturing the electrode sheet as described in claim 8, wherein, In the stepped roller pressing process, the tension applied to the unformed portion when the stepped roller is pressed onto the unformed portion is smaller than the tension applied to the unformed portion before and after the pair of rubber rollers.

10. The method for manufacturing the electrode sheet as described in claim 8 or 9, wherein, The at least one rubber roller comprises: The first part, the first part presses on the boundary portion; and The second and third parts press on the outer side of the boundary portion. In the first part, the thickness of the elastomer is fixed. In the second part, the elastomer gradually thickens from the end of the first part toward the axially outward side. In the third part, the thickness of the elastomer is fixed from the end of the second part toward the axially outward side.

11. The method for manufacturing the electrode sheet as described in claim 10, wherein, The at least one rubber roller is positioned at the inner end corresponding to the end of the active material layer. The first part covers the boundary portion. The length of the second part is smaller than the width of the unformed part. The combined length of the first portion and the second portion is more than 0.6 times and less than 0.85 times the width of the overlap between the electrode sheet and the at least one rubber roller.

12. The method for manufacturing the electrode sheet as described in claim 10, wherein, The length by which at least one rubber roller is pressed against at least one of the electrode sheet and the other rubber roller is more than 1.2 times and less than 2.1 times the width of the unformed portion pressed by the pair of rubber rollers.

13. The method for manufacturing the electrode sheet as described in claim 12, wherein, In the second part, the elastomer is inclined at an angle of more than 10 degrees and less than 25 degrees, such that it thickens from the end of the first part toward the axially outward.

14. The method for manufacturing the electrode sheet as described in claim 12, wherein, The thickness of the elastomer in the third part is more than 1.3 times and less than 2.0 times the thickness of the elastomer in the first part.

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