Electrode sheet manufacturing apparatus and electrode sheet manufacturing method

Abstract

Suppression of wrinkles in electrode sheets. [Solution] The electrode sheet manufacturing apparatus 1 comprises a conveying device 102, a first pressing device 104, a second pressing device 106, and a stepped roll pressing device 108. The first pressing device 104 is a device that roll-presses the unformed portion of the electrode sheet 10 with a pair of rubber rolls 30, 35. The second pressing device 106 is a device that roll-presses the active material layer. The stepped roll pressing device 108 is a device that applies tension to the unformed portion of the electrode sheet 10 by pressing a stepped roll 50 against it. The upper roll 30 comprises a shaft 31 and an elastic body 32. The diameter of the shaft 31 in the part that presses the boundary between the unformed portion and the active material layer is larger than the diameter of the shaft 31 in the part that presses outside the boundary portion. The thickness of the elastic body 32 in the part that presses the boundary portion is thinner than the thickness of the elastic body 32 in the part that presses outside the boundary portion.

Description

Technical Field

[0001] The present invention relates to an electrode sheet manufacturing apparatus and a method for manufacturing an electrode sheet.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2023-036089 discloses a method for manufacturing an electrode having a coating portion pressing step of pressing a coating portion disposed on a metal foil in the thickness direction and an uncoated portion pressing step of pressing an uncoated portion in the thickness direction.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the present inventor has found that wrinkles occur in the electrode sheet even when the uncoated portion is pressed by a pair of elastic rolls when the electrode sheet is roll-pressed.

Means for Solving the Problems

[0005] The electrode sheet manufacturing apparatus disclosed herein is a manufacturing apparatus for manufacturing an electrode sheet having a current collector, an unformed portion, and an active material layer. The current collector is made of a long metal foil. The unformed portion is set along the length direction at a predetermined position in the width direction of the current collector. The active material layer is formed on the part of the current collector excluding the unformed portion. The electrode sheet manufacturing apparatus comprises a conveying device, a first press device, a second press device, and a roll pressing device. The conveying device conveys the electrode sheet along a predetermined conveying path. The first press device is located along the conveying path and roll-presses the unformed portion of the electrode sheet with a pair of rubber rolls. The second press device is located downstream of the first press device in the conveying path and roll-presses the active material layer. The stepped roll pressing device is located downstream of the second press device in the conveying path and applies tension to the unformed portion of the electrode sheet by pressing a stepped roll against it. The stepped roll has a step in the portion of the unformed portion that corresponds to the boundary with the active material layer. In a stepped roll, the diameter of the portion corresponding to the unformed area is larger than the diameter of the portion corresponding to the active material layer. At least one of the pair of rubber rolls comprises a shaft and an elastic body wound around the shaft. In at least one of the rubber rolls, the diameter of the shaft in the portion that presses the boundary between the unformed area and the active material layer is larger than the diameter of the shaft in the portion that presses the area outside the boundary. In at least one of the rubber rolls, the thickness of the elastic body in the portion that presses the boundary is thinner than the thickness of the elastic body in the portion that presses the area outside the boundary. With such an electrode sheet manufacturing apparatus, wrinkling of the electrode sheet is easily suppressed. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a manufacturing flow chart for the electrode sheet manufacturing method. [Figure 2] Figure 2 is a schematic diagram of the electrode sheet 10. [Figure 3] Figure 3 is a schematic diagram showing another form of the electrode sheet 10. [Figure 4] Figure 4 is a schematic diagram showing an example of the roll press process S6 proposed here. [Figure 5] Figure 5 is a schematic diagram of the first press device 104. [Figure 6] Figure 6 is a schematic diagram of the stepped roll pressing process S6c. [Figure 7] Figure 7 is a schematic diagram showing the elongation of the electrode sheet 10 that is roll-pressed in the first pressing process S6a. [Figure 8] Figure 8 is a schematic diagram showing the extension of the current collector 12. [Modes for carrying out the invention]

[0007] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiment described herein is, of course, not intended to particularly limit the present invention. Each drawing is schematic and does not necessarily reflect the actual object. Furthermore, components and parts that perform the same function are appropriately denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. In this specification, notations such as "X~Y" indicating a numerical range mean "X or greater and Y or less" unless otherwise specified.

[0008] Figure 1 is a flow chart of the manufacturing process for electrode sheets. As shown in Figure 1, the manufacturing process for electrode sheets includes a conveying process S1, a weighing process S2, a kneading process S3, a coating process S4, a drying process S5, and a roll pressing process S6. However, the manufacturing process for electrode sheets may include other processes.

[0009] <Electrode Sheet 10> Figure 2 is a schematic diagram of the electrode sheet 10. The electrode sheet 10 constitutes the positive or negative electrode sheet of the electrode body housed inside the energy storage device. An energy storage device is a device that can be repeatedly charged and discharged, and is a concept that includes not only so-called rechargeable batteries (i.e., chemical batteries) such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, but also capacitors (i.e., physical batteries) such as electric double-layer capacitors.

[0010] As shown in Figure 2, the electrode sheet 10 comprises 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 having the required conductivity can be used. For example, aluminum, aluminum alloy, etc. can be used as the positive electrode current collector foil. For example, copper, copper alloy, etc. can be used as the negative electrode current collector foil. The active material layer 14 is coated on the current collector 12 at predetermined positions. 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 sides of the current collector 12. The active material layer 14 is a layer containing electrode active material. For example, lithium transition metal composite oxide can be used as the positive electrode active material. For example, carbon material, silicon-based material, and mixed oxides thereof can be used as the negative electrode active material. The active material layer may contain additives other than electrode active materials, such as binders and conductive materials.

[0011] The electrode sheet 10 is formed by coating the current collector 12 with an electrode mixture slurry that will become the active material layer 14, and then drying it. The current collector 12 has an uncoated portion 12a (unformed portion) and a coated portion 12b. The uncoated portion 12a is the part of the current collector 12 to which the active material layer 14 has not been coated. The uncoated portion 12a is set along the length direction at the widthwise end of the electrode sheet 10. In this embodiment, the uncoated portion 12a is set at both ends of the electrode sheet 10 in the widthwise direction. The coated portion 12b is positioned between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode mixture slurry is coated onto the coated portion 12b. As a result, the active material layer 14 is formed on the coated portion 12b of the current collector 12. That is, the active material layer 14 is positioned between the uncoated portions 12a at both ends of the electrode sheet 10 in the widthwise direction. Thus, the electrode sheet 10 preferably has a current collector 12 made of a long metal foil, an unformed portion (here, an uncoated portion 12a) set along the length direction at a predetermined position in the width direction of the current collector 12, and an active material layer 14 formed on the part of the current collector 12 excluding the unformed portion.

[0012] Figure 3 is a schematic diagram showing another form of the electrode sheet 10. As shown in Figure 3, the electrode sheet 10 may have an insulating protective layer 12c in the uncoated portion 12a adjacent to the coated portion 12b. Such a structure may be used, for example, in an electrode sheet 10 used as a positive electrode. By providing the protective layer 12c on the electrode sheet 10 used as a positive electrode, a short circuit between the positive electrode current collector foil and the negative electrode active material layer can be prevented. Such a protective layer 12c contains an insulating inorganic filler. An example of an inorganic filler is insulating particles, such as ceramic particles such as alumina. The protective layer 12c may also contain, for example, a binder. The binder may be the same as the one exemplified as being included in the positive electrode active material layer. In the following, unless otherwise specified, Figures 2 and 3 will be referenced as appropriate for the components of the electrode sheet 10.

[0013] <Transportation process S1, measurement process S2, kneading process S3, coating process S4, drying process S5> In the transport process S1 shown in Figure 1, the electrode sheet 10 is transported. In the transport process S1, the electrode sheet 10 is transported along a predetermined transport path W1 (see Figure 4). In the weighing process S2, the raw materials for the active material layer 14 (see Figure 2) are weighed. This weighing can be achieved by a weighing device (not shown) having, for example, a balance or load cell. The weighed raw materials for the active material layer 14 are mixed in the kneading process S3. The kneading process S3 can be achieved by a kneading device (not shown). The raw materials for the active material layer 14, which have been turned into a slurry by the kneading device, are coated onto the current collector 12 (see Figure 2) in the coating process S4. The coating process S4 can be achieved by a coating device (not shown) such as a slit coater, gravure coater, die coater, or comma coater. In the drying process S5, the coated slurry-like raw materials for the active material layer 14 are dried. The drying process S5 can be implemented, for example, by a drying device (not shown) that emits hot air or infrared rays.

[0014] <Roll press process S6> The roll pressing process S6 is a process of roll pressing the electrode sheet 10. Here, the base material of the electrode sheet 10 is metal foil. The electrode sheet 10 has areas where the active material layer 14 is formed (coated area 12b) and areas where the active material layer 14 is not formed (uncoated area 12a). The roll pressing process S6 is mainly intended to adjust the density of the active material layer 14 formed by coating to an appropriate level.

[0015] In the roll pressing process S6, the coated portion 12b is roll-pressed to achieve the appropriate density of the active material layer 14. When the coated portion 12b is roll-pressed, the current collector 12 of the substrate stretches in the coated portion 12b, but in the uncoated portion 12a, the pressing pressure is not directly transmitted, and the current collector 12 of the substrate does not stretch easily. Therefore, if only the coated portion 12b is pressed, variations in the stretching of the current collector 12 may occur between the coated portion 12b and the uncoated portion 12a. If there is a large variation in the stretching of the current collector 12 between the coated portion 12b and the uncoated portion 12a, it may cause wrinkles to form in the electrode sheet 10. The uncoated portion 12a is cut into a predetermined shape in a later process to form tabs. At this time, if wrinkles occur in the boundary portion 12d between the uncoated portion 12a and the active material layer 14, the tabs may not be formed in the appropriate shape.

[0016] To prevent wrinkles from forming in the electrode sheet 10, it is preferable to stretch the current collector 12 in the uncoated portion 12a before or after roll-pressing the coated portion 12b. One technique for stretching the current collector 12 in the uncoated portion 12a is to press the uncoated portion 12a with a rubber roll. The technique of pressing the uncoated portion 12a with a rubber roll is appropriately referred to as EPS (Elasticity Powered Stretching). Furthermore, the device used to press the uncoated portion 12a with a rubber roll may appropriately be referred to as an EPS device.

[0017] Incidentally, the present inventors have found that wrinkles occur in the electrode sheet 10 even when the uncoated portion 12a is stretched by EPS before and after the roll press. The wrinkles particularly occur at the boundary portion 12d between the uncoated portion 12a and the active material layer 14. Regarding such an event, the present inventors have obtained the finding that when stretching the uncoated portion 12a with EPS, the boundary portion 12d between the uncoated portion 12a and the active material layer 14 cannot be properly stretched.

[0018] That is, in the coated portion 12b, an active material layer 14 is formed. The active material layer 14 is a layer coated with a metal oxide such as a lithium transition metal composite oxide. When the rubber roll of EPS is pressed against the active material layer 14, it causes the active material layer 14 to peel off. From such a viewpoint, in EPS, the position of the rubber roll is set so that the rubber roll does not hit the coated portion 12b. As a result, in EPS, it is difficult to stretch the boundary and its vicinity between the uncoated portion 12a and the coated portion 12b. In addition, a protective layer containing an inorganic filler may be formed at the boundary between the uncoated portion 12a and the coated portion 12b. When the protective layer is formed, when the rubber roll of EPS is pressed, the elongation rate may not match between the site where the protective layer is formed and the site where the protective layer is not formed.

[0019] Thus, when stretching the uncoated portion 12a with EPS, it is difficult to properly stretch the boundary portion 12d between the uncoated portion 12a and the active material layer 14. As a result, the present inventors believe that distortion remains in the boundary portion 12d and wrinkles occur in the electrode sheet.

[0020] FIG. 4 is a schematic diagram showing an example of the roll press process S6 proposed here. As shown in FIG. 4, the roll press process S6 includes a first press process S6a, a second press process S6b, and a stepped roll pressing process S6c.

[0021] The first pressing step S6a is the process of stretching the uncoated portion 12a of the electrode sheet 10, as described above. Figure 5 is a schematic diagram of the first pressing device 104. In Figure 5, the electrode sheet 10 and the pair of rubber rolls 30 and 35 are shown as being virtually separated. Figure 5 schematically shows the cross-sections of the electrode sheet 10 and the pair of rubber rolls 30 and 35. The first pressing step S6a is performed by the first pressing device 104. As shown in Figure 5, the first pressing step S6a is the process of roll pressing the uncoated portion 12a of the electrode sheet 10 with the pair of rubber rolls 30 and 35 while the electrode sheet 10 is transported along a predetermined transport path. Here, the pair of rubber rolls 30 and 35 are roll pressed under tension. Although not particularly limited, the tension applied to the electrode sheet 10 before and after the pair of rubber rolls 30, 35 is 150N to 250N, and for example, it may be about 170N to 230N (about 200N in this embodiment).

[0022] The rubber rolls 30 and 35 are preferably roll members in which elastic bodies 32 and 37 are arranged on shafts 31 and 36. The elastic bodies 32 and 37 used in the rubber rolls 30 and 35 are preferably elastic materials having the required Young's modulus. Examples of elastic bodies 32 and 37 include rubber and resins such as urethane. In the first pressing step S6a, the uncoated portion 12a is pressed by the rubber rolls 30 and 35, and the portion being pressed by the rolls is pressed and stretched by the reaction force of the elastic and compressive deformation of the rubber rolls.

[0023] The second pressing step S6b is a process in which the active material layer 14 (coated portion 12b) of the electrode sheet 10 is roll-pressed after the first pressing step S6a, as shown in Figure 4. This step adjusts the active material layer 14 (coated portion 12b) to the required density. In the second pressing step S6b, as shown in Figure 4, the electrode sheet 10 is sandwiched between a pair of rolls 41 and 42, and the active material layer 14 is compressed. At this time, the current collector 12, which is the base material, is stretched in the area where the active material layer 14 is formed (coated portion 12b).

[0024] The stepped roll pressing process S6c is a process in which the stepped roll 50 is pressed against the uncoated portion 12a of the electrode sheet 10 after the first pressing process S6a to apply tension. Figure 6 is a schematic diagram of the stepped roll pressing process S6c.

[0025] <Stepped Roll 50> As shown in Figure 6, the stepped roll 50 used in process S6c has a step 51a at the portion 51 corresponding to the boundary portion 12d between the uncoated portion 12a and the active material layer 14. The diameter of the portion 52 corresponding to the uncoated portion 12a is larger than the diameter of the portion 53 corresponding to the active material layer 14. In the configuration shown in Figure 6, the diameter of the portion 52 corresponding to the uncoated portion 12a is preferably uniform. The diameter of the portion 53 corresponding to the active material layer 14 is also uniform.

[0026] Here, the boundary portion 12d between the uncoated portion 12a and the active material layer 14 can be the boundary and vicinity of the boundary between the active material layer 14 and the uncoated portion 12a of the electrode sheet 10. 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, which is the base material, is less likely to stretch in the first pressing step S6a, which stretches the uncoated portion 12a, and the second pressing step S6b, which roll-presses 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 (for example, about 5 mm). A protective layer 12c may be formed at the boundary portion 12d between the active material layer 14 and the uncoated portion 12a, as shown in Figure 3.

[0027] As shown in Figure 6, the step 51a is provided at the portion 51 corresponding to the boundary portion 12d between the uncoated portion 12a and the active material layer 14. In the configuration shown in Figure 6, the height of the step 51a should be set such that when the electrode sheet 10 is wound around the stepped roll 50 and transported, the boundary portion 12d between the uncoated portion 12a and the active material layer 14 is struck and stretched. From this perspective, the height of the step 51a also depends on the specifications of the electrode sheet 10 (for example, the thickness of the current collector 12 and the thickness of the active material layer 14 of the coated portion 12b). When the electrode sheet 10 is wound around the stepped roll 50 and transported, tension is applied to the electrode sheet 10. The tension applied to the electrode sheet 10 is 80N to 200N, and can be, for example, about 100N to 160N (about 140N in this embodiment). In this embodiment, when the stepped roll 50 is pressed against the uncoated portion 12a, the tension applied to the uncoated portion 12a is set to be less than the tension applied to the uncoated portion 12a before and after the pair of rubber rolls 30, 35 (see Figure 4).

[0028] Here, the height h1 of the step 51a is defined as the radial distance of the stepped roll 50 from the portion corresponding to the coated portion 12b to the portion corresponding to the uncoated portion 12a. The height h1 of the step 51a is not particularly limited, but may be, for example, 0.25 mm or more and 1.50 mm or less. The height h1 of the step 51a may be 3.00 mm or less. The step 51a is composed of an inclined surface 51a1 that is uniformly inclined with respect to the axial direction of the stepped roll 50. The inclination angle of the inclined surface 51a1 may be, for example, 15 degrees or more and 45 degrees or less with respect to the axial direction of the stepped roll 50, preferably 30 degrees. In addition, the start and end points of the inclined surface 51a1 are preferably given an R chamfer, for example, R=2.5 is preferred.

[0029] <Method for manufacturing electrode sheets> The method for manufacturing the electrode sheet 10 proposed here is carried out in the following order, as shown in Figure 4: first pressing step S6a, second pressing step S6b, and stepped roll pressing step S6c.

[0030] In the first pressing step S6a, an EPS device is preferably used to press the uncoated portion 12a with rubber rolls 30 and 35. In this case, the position and pressing force of the rubber rolls 30 and 35 are preferably adjusted in the EPS device so that the uncoated portion 12a is pressed by the rubber rolls 30 and 35. In addition, the position of the electrode sheet 10 being transported toward the EPS device is preferably adjusted so that the position of the uncoated portion 12a aligns with the position of the rubber rolls 30 and 35 of the EPS device. In the stepped roll pressing step S6c, the position of the electrode sheet 10 is preferably adjusted relative to the stepped roll 50 so that the step 51a of the stepped roll 50 contacts the boundary portion 12d between the uncoated portion 12a and the active material layer 14. In this embodiment, the stepped roll 50 is thicker in the portion that contacts the uncoated portion 12a. Therefore, in the stepped roll pressing step S6c, the uncoated portion 12a that has already been stretched in the first pressing step S6a is supported by the stepped roll 50.

[0031] <Electrode Sheet Manufacturing Apparatus 1> The electrode sheet manufacturing apparatus 1, which embodies the method for manufacturing such an electrode sheet, includes a roll press unit 100 for roll pressing a strip-shaped electrode sheet 10, as shown in Figure 4. The roll press unit 100 includes a conveying device 102, a first press device 104, a second press device 106, and a stepped roll pressing device 108. The roll press unit 100 may also include guide rolls 54-59 and tension rolls 61, 62. The positions of the guide rolls 54-59 and tension rolls 61, 62 are not particularly limited. In the embodiment shown in Figure 4, the stepped roll pressing device 108 has one stepped roll 50, but is not limited to this configuration. The stepped roll pressing device 108 may be provided with a plurality of stepped rolls 50 (not particularly limited, but for example, three). When the stepped roll pressing device 108 is provided with a plurality of stepped rolls 50, guide rolls may be provided between adjacent stepped rolls 50 on the conveying path W1. The number of stepped rolls 50 can be set appropriately according to the desired elongation rate of the current collector 12, the quality of the completed electrode sheet 10, and so on.

[0032] <Conveying device 102> The transport device 102 is a device that transports the electrode sheet 10 along a predetermined transport path W1. Details of the transport device 102 are omitted, but it is a device that transports the electrode sheet 10 along the transport path W1. Although not shown in the diagram, the transport device 102 may include a mechanism for feeding the electrode sheet 10 along the transport path W1, a guide roll for moving the electrode sheet 10 along the transport path W1, a tension adjustment mechanism for applying the required tension to the electrode sheet 10, and a mechanism for winding up the electrode sheet 10 that has been transported along the transport path W1.

[0033] <First Pressing Device 104> The first press device 104 is positioned on the transport path W1 and is a device that roll-presses the uncoated portion 12a of the electrode sheet 10 with a pair of rubber rolls 30 and 35. The first press device 104 preferably uses an EPS device with rubber rolls 30 and 35 as described above. In the EPS device, the position and pressing force of the rubber rolls 30 and 35 should be adjusted so that the uncoated portion 12a is pressed by the rubber rolls 30 and 35. It is also preferable to have a position adjustment device (not shown) that adjusts the position of the electrode sheet 10 being transported toward the EPS device so that the position of the uncoated portion 12a aligns with the position of the rubber rolls 30 and 35 of the EPS device.

[0034] As shown in Figure 5, the pair of rubber rolls 30, 35 comprises an upper roll 30 and a lower roll 35. The axes of rotation of the upper roll 30 and the lower roll 35 are substantially parallel. It is preferable that one of the upper roll 30 and the lower roll 35 be configured to be drivable relative to the other. In this embodiment, the upper roll 30 is pressed against the lower roll 35. As a result, the pair of rubber rolls 30, 35 roll-press the electrode sheet 10.

[0035] <Lower Roll 35> The lower roll 35 is a cylindrical roll positioned below the electrode sheet 10. The lower roll 35 is longer in the axial direction than the width direction of the electrode sheet 10. The ends of the lower roll 35 protrude outward from the electrode sheet 10. The lower roll 35 is in contact with the uncoated portion 12a of the current collector 12 and the active material layer 14, and supports the entire surface of the electrode sheet 10 from below in the width direction of the electrode sheet 10. Note that the lower roll 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.

[0036] The lower roll 35 comprises a shaft 36 and an elastic body 37. In this embodiment, the shaft 36 is substantially cylindrical and has a substantially constant radius along its length. The elastic body 37 is wound around the shaft 36. The length of the elastic body 37 is substantially the same as the length of the shaft 36. Although not particularly limited, the thickness of the elastic body 37 can be set to approximately 5 mm to 20 mm (for example, approximately 8 mm to 16 mm). The elastic body 37 is substantially cylindrical and has a substantially constant thickness in the circumferential and longitudinal directions. Therefore, the radius of the lower roll 35 is substantially constant along its length. An upper roll 30 is provided above the lower roll 35.

[0037] <Upper Roll 30> The upper roll 30 is a disc-shaped roll positioned above the electrode sheet 10. The upper roll 30 is positioned to press the uncoated portion 12a of the electrode sheet 10. The inner end 30d of the upper roll 30 may be positioned near the boundary between the uncoated portion 12a and the coated portion 12b. In this embodiment, the inner end 30d of the upper roll 30 is positioned to correspond to the edge of the active material layer 14. The inner end 30d of the upper roll 30 is set to slightly overlap with the coated portion 12b. The upper roll 30 is set to dimensions that allow it to press the uncoated portion 12a of the electrode sheet 10. The width (axial dimension) of the upper roll 30 is greater than the width of the uncoated portion 12a of the electrode sheet 10. The outer end 30e of the upper roll 30 protrudes outward beyond the edge of the uncoated portion 12a. The width of the upper roll 30 is not particularly limited and may be set to dimensions that do not protrude outward beyond the lower roll 35.

[0038] The upper roll 30 comprises a shaft 31 and an elastic body 32. In this embodiment, the shaft 31 is substantially disc-shaped and has a substantially constant radius along its length. The elastic body 32 is wound around the shaft 31. The length of the elastic body 32 is substantially the same as the length of the shaft 31. The elastic body 32 is substantially cylindrical and has a substantially constant thickness in the circumferential and longitudinal directions, except for the end 33. The corners of both end 33 are chamfered. The corners of the end 33 are continuously inclined in the circumferential direction. The shape of the end 33 is not particularly limited and may be a shape in which a radius is formed continuously in the circumferential direction. The end 33 may not be chamfered and its corners may be substantially vertical. In this embodiment, both end 33 are chamfered with an axial dimension of C1 (see Figure 5). The angle of the chamfer can be 30 to 60 degrees. In this embodiment, the angle of the chamfer is approximately 45 degrees.

[0039] The upper roll 30 comprises a first portion 30a, a second portion 30b, and a third portion 30c, in order from the inner end 30d to the outer end 30e. The first portion 30a is the portion 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 portions that press the area outside the boundary portion 12d. For this reason, the first portion 30a is positioned to overlap with the boundary portion 12d of the electrode sheet 10. The second portion 30b and the third portion 30c are positioned outside 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 roll 30.

[0040] The shaft 31 comprises a first portion 31a, a second portion 31b, and a third portion 31c. The second portion 31b is continuous with the axial outer end of the first portion 31a. The third portion 31c is continuous with the axial outer end of the second portion 31b. The elastic body 32 comprises a first portion 32a, a second portion 32b, and a third portion 32c. The second portion 32b is continuous with the axial outer end of the first portion 32a. The third portion 32c is continuous with the axial outer end of the second portion 32b. The first portion 32a, the second portion 32b, and the third portion 32c of the elastic body 32 are wound around the first portion 31a, the second portion 31b, and the third portion 31c of the shaft 31, respectively. The first part 31a, second part 31b, and third part 31c of the shaft 31, and the first part 32a, second part 32b, and third part 32c of the elastic body 32, correspond to the first part 30a, second part 30b, and third part 30c of the upper roll 30, respectively.

[0041] The shaft 31 has different diameters along its length. In this embodiment, the diameter of the first portion 31a is substantially constant in the axial direction. The diameter of the second portion 31b gradually decreases toward the axial outward direction. In other words, the second portion 31b is inclined such that its diameter decreases toward the axial outward direction. The diameter of the third portion 31c is substantially constant in the axial direction. Therefore, the diameter of the first portion 31a is larger than the diameters of the second portion 31b and the third portion 31c.

[0042] The elastic body 32 has different thicknesses along its length. In this embodiment, the thickness of the first portion 32a is approximately constant in the axial direction. The thickness of the first portion 32a may be about the same as the thickness of the elastic body 37 of the lower roll 35. The thickness of the second portion 32b gradually increases toward the axially outward direction. In other words, the inner circumferential surface of the second portion 32b is inclined to become thicker toward the axially outward direction. In this embodiment, the inner circumferential surface of the second portion 32b is thicker toward the axially outward direction. The thickness of the third portion 32c is approximately constant 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. Because the thickness of the elastic body 32 in the second portion 32b gradually increases toward the axially outward direction, it is easy to adjust the elongation of the uncoated portion 12a in the width direction.

[0043] Although not particularly limited, the thickness of the elastic body 32 can be set to approximately 5 mm to 20 mm (for example, approximately 8 mm to 16 mm) in any of the first part 32a to the third part 32c.

[0044] In the second portion 32b, the elastic body 32 may be inclined at an angle of 10 to 25 degrees (for example, about 12 to 20 degrees) such that it becomes thicker axially outward from the end of the first portion 32a. Similarly, the second portion 31b of the shaft 31 is also inclined at an angle corresponding to the second portion 32b of the elastic body 32 such that it becomes thinner axially outward from the end of the first portion 31a. Note that the angle of inclination of the elastic body 32 in the second portion 32b is not particularly limited.

[0045] The thickness of the elastic body 32 in the third portion 32c may be set to be between 1.3 and 2.0 times the thickness of the elastic body 32 in the first portion 32a. The thickness of the third portion 32c of the elastic body 32 may also be set to be between 1.4 and 1.8 times the thickness of the first portion 32a, for example.

[0046] Here, the length Y1 of the first portion 30a is greater than the width C1 + X1 from the inner end 30d of the upper roll 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 inward beyond the inner end of the boundary portion 12d, and the outer end of the first portion 30a reaches outward beyond the outer end of the boundary portion 12d. In other words, the first portion 30a is positioned and sized to cover the boundary portion 12d. Therefore, the boundary portion 12d is pressurized by the first portion 30a.

[0047] The length Y2 of the second portion 30b is smaller than the width X2 of the uncoated portion 12a. Here, if 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 edge of the protective layer 12c to the outer edge of the electrode sheet 10. If a protective layer 12c is not formed on the electrode sheet 10, the width X2 of the uncoated portion 12a is the width from the outer edge of the active material layer 14 to the outer edge of the electrode sheet 10. The second portion 30b overlaps with a portion of the uncoated portion 12a. The position and dimensions of the second portion 30b are set to fit 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.

[0048] The combined length Y1+Y2 of the first part 30a and the second part 30b is 0.6 to 0.85 times (for example, 0.65 to 0.8 times) the width C1+X1+X2 where the electrode sheet 10 and the upper roll 30 overlap. In this embodiment, since the inner end 30d of the upper roll 30 is set to overlap with the coated portion 12b, the width where the electrode sheet 10 and the upper roll 30 overlap is wider than the width of the uncoated portion 12a including the boundary portion 12d.

[0049] In this embodiment, the length Y3 over which the upper roll 30 is pressed against the lower roll 35 is 1.2 to 2.1 times (for example, 1.6 to 2.0 times) the width X1 + X2 over which the unformed portion 12a is pressed by the pair of rubber rolls 30 and 35 (the width over which the pair of rubber rolls 30 and 35 press against the unformed portion 12a). Therefore, the outer end of the unformed portion 12a is pressed by the outer part of the upper roll 30 from approximately the center.

[0050] Figure 7 is a schematic diagram showing the elongation of the electrode sheet 10 roll-pressed in the first pressing process S6a. Figure 7 schematically shows a plan view of the electrode sheet 10. The elongation of the electrode sheet 10 is indicated by arrows, with longer arrows indicating greater elongation. In the plan view of the electrode sheet 10, the position pressed by the upper roll 30 is indicated by a dashed line. Note that Figure 7 only virtually illustrates the elongation of the electrode sheet 10, and the relative magnitudes of elongation in each part of the electrode sheet 10 are not necessarily as shown in Figure 7.

[0051] In the inventor's trials, as shown in Figure 7, in portions of the upper roll 30 with similar thickness, the elongation of the uncoated portion 12a increased closer to the center of the portion (solid arrow). Furthermore, the elongation of the uncoated portion 12a increased in portions of the upper roll 30 that were roll-pressed in thinner portions of the elastic body 32 (for example, the first portion 30a) (dashed arrow). Note that the boundary portion 12d near the active material layer 14 (or the portion where the protective layer 12c is formed) is a portion where the current collector 12 does not stretch easily, as described above. Also, there are parts of the protective layer 12c that are not pressed by the upper roll 30. In addition, in this embodiment, since the end portion 33 is chamfered, only a portion of the boundary portion 12d is roll-pressed. For this reason, the elongation of the boundary portion 12d of the uncoated portion 12a is minute.

[0052] In the embodiment described above, the combined length Y1+Y2 of the first portion 30a and the second portion 30b is set to 0.6 times or more the width C1+X1+X2 where the electrode sheet 10 and the upper roll 30 overlap. This allows the outer end of the uncoated portion 12a to be pressed by the third portion 30c, which has a similar thickness to the elastic body 32. The central part of the uncoated portion 12a can be pressed by the second portion 30b, which has a thinner elastic body 32. The portion pressed by the third portion 30c is adjusted to an appropriate range, making it easy to adjust the elongation of the central part of the uncoated portion 12a to be similar to that of the outer end.

[0053] In the embodiment described above, the combined length Y1+Y2 of the first portion 30a and the second portion 30b is set to be 0.85 times or less the width C1+X1+X2 where the electrode sheet 10 and the upper roll 30 overlap. This prevents the thickness of the elastic body 32 of the third portion 30c, which presses the outer edge of the uncoated portion 12a, from becoming excessively thick. As a result, the elongation of the outer edge of the uncoated portion 12a, which is pressed by the third portion 30c, is easily maintained.

[0054] In the embodiment described above, the length Y3 over which the upper roll 30 is pressed against the lower roll 35 is 1.2 to 2.1 times the width X1 + X2 over which the unformed portion 12a is pressed by the pair of rubber rolls 30 and 35. This makes it easier for the outer end of the uncoated portion 12a to be pressed near the center of the third portion 30c of the upper roll 30. Because the outer end of the uncoated portion 12a is pressed near the center of the third portion 30c, where the elastic body 32 is thicker, the elongation is easily maintained. As a result, the elongation of the outer end and the center of the uncoated portion 12a tends to be about the same.

[0055] In the embodiment described above, in the second portion 32b, the elastic body 32 is inclined at an angle of 10 degrees or more so that it becomes thicker axially outward from the end of the first portion 32a. This can increase the thickness difference between the first portion 30a and the third portion 30c. As a result, in the first pressing step S6a, the elongation near the boundary portion 12d of the uncoated portion 12a pressed by the first portion 30a tends to be relatively large. Therefore, the area near the boundary portion 12d of the uncoated portion 12a may be stretched locally in the stepped roll pressing step S6c. Consequently, the uncoated portion 12a of the electrode sheet 10 tends to be stretched uniformly as a whole.

[0056] In the embodiment described above, in the second portion 32b, the elastic body 32 is inclined at an angle of 25 degrees or less so that it becomes thicker axially outward from the end of the first portion 32a. As a result, the difference in stress distribution in the electrode sheet 10 is less likely to become large in the vicinity of the portion pressed by the second portion 30b. Consequently, damage to the electrode sheet 10 is less likely to occur.

[0057] In the embodiment described above, the thickness of the elastic body 32 in the third portion 32c is set to 1.3 times or more the thickness of the elastic body 32 in the first portion 32a. This prevents the difference in elongation between the boundary portion 12d of the uncoated portion 12a and the outer end of the uncoated portion 12a from becoming excessively large. As a result, when stretching the boundary portion 12d of the uncoated portion 12a in the stepped roll pressing process S6c, the tension applied to the boundary portion 12d of the uncoated portion 12a can be small. Consequently, damage to the electrode sheet 10 in the stepped roll pressing process S6c is easily suppressed.

[0058] In the embodiment described above, the thickness of the elastic body 32 in the third portion 32c is set to 2.0 times or less the thickness of the elastic body 32 in the first portion 32a. This makes it easier to appropriately suppress the elongation of the boundary portion 12d of the uncoated portion 12a. For this reason, 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 sandwiched between the pair of rolls 41 and 42 in the second pressing step S6b, the boundary portion 12d is less likely to swing up and down. By suppressing the swinging of the boundary portion 12d, concerns such as damage to the rolls 41 and 42 and fracture of the boundary portion 12d due to the pair of rolls 41 and 42 biting into the boundary portion 12d can be reduced.

[0059] As shown in Figure 4, the electrode sheet 10, roll-pressed by the first press device 104, is placed on the tension roll 61 and guide rolls 54, 55 and transported to the second press device 106. The tension roll 61 is configured to adjust the tension applied to the electrode sheet 10 between the first press device 104 and the second press device 106. The tension applied to the electrode sheet 10 between the first press device 104 and the second press 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 transport path W1.

[0060] <Second Pressing Device 106> The second press device 106 is located downstream of the first press device 104 in the transport path W1. The second press device 106 is a device that roll-presses the active material layer 14. It is equipped with a pair of rolls (rolling rolls) 41 and 42. The pair of rolls 41 and 42 are each substantially cylindrical rolls and extend along the width direction of the active material layer 14 of the electrode sheet 10. In the second press device 106, the pair of rolls 41 and 42 are configured to be rotatable by a drive device (not shown) that rotates the rolls 41 and 42. The pair of rolls 41 and 42 are rotated in contact with each other, and the electrode sheet 10 is passed between them. At that time, the coated portion 12b of the electrode sheet 10 is stretched along the transport direction.

[0061] The electrode sheet 10, roll-pressed by the second press device 106, is transported to the stepped roll pressing device 108. The electrode sheet 10 may also be transported to the stepped roll pressing device 108 while being placed on guide rolls.

[0062] <Stepped Roll Pressing Device 108> The stepped roll pressing device 108 is positioned on the transport path W1 and is a device that presses the stepped roll 50 against the electrode sheet 10. A specific example of the shape of the stepped roll 50 is as described above. In the stepped roll pressing device 108, as shown in Figure 6, a step 51a is provided to match the boundary portion 12d between the uncoated portion 12a of the electrode sheet 10 and the active material layer 14. Furthermore, the diameter of the portion 52 corresponding to the uncoated portion 12a is larger than the diameter of the portion 53 corresponding to the active material layer 14. In the stepped roll pressing device 108, the electrode sheet 10 is transported with its position adjusted so that the boundary portion 12d between the uncoated portion 12a and the active material layer 14 aligns with the step 51a of the stepped roll 50. For this reason, it is preferable to provide a position adjustment device (not shown) in front of the stepped roll 50 to adjust the position of the electrode sheet 10.

[0063] In this manner, the stepped roll pressing device 108 is used to transport the electrode sheet 10 while the stepped roll 50 is pressed against the boundary portion 12d of the uncoated portion 12a of the electrode sheet 10 with the active material layer 14. Here, the stepped roll pressing device 108 is located downstream of the first press device 104 (first press process S6a) which stretches the uncoated portion 12a and the second press device 106 (second press process S6b) which stretches the coated portion 12b. After the uncoated portion 12a and the coated portion 12b of the electrode sheet 10 are stretched, the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is stretched by the stepped roll 50. Furthermore, the diameter of the portion 52 of the stepped roll 50 that corresponds to the uncoated portion 12a is larger than the diameter of the portion 53 that corresponds to the active material layer 14.

[0064] Therefore, the uncoated portion 12a and the active material layer 14, which have already been stretched by the first press device 104, are appropriately supported by the stepped roll 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 roll 50 and straightened. As a result, the electrode sheet 10 is less likely to break when it is pressed against the stepped roll 50.

[0065] Downstream of the stepped roll pressing device 108, a tension roll 62 and guide rolls 58 and 59 are provided. The tension roll 62 is configured to adjust the tension applied to the electrode sheet 10 downstream of the second press device 106. The tension applied to the electrode sheet 10 downstream of the second press device 106 is controlled by the control device 110.

[0066] Figure 8 is a schematic diagram showing the elongation of the current collector 12. In Figure 8, the elongation of the electrode sheet 10 in each of the first pressing process S6a, the second pressing process S6b, and the stepped roll pressing process S6c is shown by solid arrows. In Figure 8, the portion of the electrode sheet 10 that was stretched in the previous process is shown by a dashed arrow. Note that Figure 8 only shows the elongation of the electrode sheet 10 virtually, and the relative magnitudes of the elongation of the electrode sheet 10 in each part are not necessarily as shown in Figure 8. As shown in Figure 8, the electrode sheet 10 is first stretched in the uncoated portion 12a by the first pressing process S6a. Then, the coated portion 12b is further stretched by the second pressing process S6b. After that, the current collector 12 at the boundary portion 12d between the uncoated portion 12a and the active material layer 14 is stretched by the stepped roll pressing process S6c. In this case, the uncoated portion 12a is stretched by the first pressing step S6a, and the coated portion 12b is stretched by the second pressing step S6b. Subsequently, the boundary portion 12d of the uncoated portion 12a is locally stretched by the stepped roll pressing step S6c. As a result, wrinkles caused by the difference in elongation rate of the current collector 12 between the boundary portion 12d with the active material layer 14 and the other portions 12a and 12b are suppressed, and wrinkles are suppressed for the electrode sheet 10 as a whole. Note that the portion of the uncoated portion 12a near the protective layer 12c (boundary portion 12d) may have insufficient elongation in the first pressing step S6a compared to the portion from the center outwards. In this embodiment, a portion of the rubber roll 30 where the elastic body 32 is thin (first portion 30a) is adjusted to overlap with the portion near the protective layer 12c (see Figure 5). Therefore, in the stepped roll pressing process S6c, the uncoated portion 12a near the protective layer 12c is also stretched to some extent. As a result, wrinkles are more easily suppressed throughout the electrode sheet 10.

[0067] Here, the process of stretching the uncoated portion 12a (first pressing step S6a) is preferably performed by EPS, as described above. As described above, with EPS, it is difficult to stretch the current collector 12 at the boundary portion 12d between the uncoated portion 12a and the active material layer 14. In the electrode sheet manufacturing method and electrode sheet manufacturing apparatus 1 proposed here, the current collector 12 at the boundary portion 12d between the uncoated portion 12a and the active material layer 14 is stretched by the stepped roll 50.

[0068] Since the boundary portion 12d is pressed against the step 51a of the stepped roll 50 and stretched, even if there is a protective layer 12c at the boundary portion 12d between the uncoated portion 12a and the active material layer 14, it is stretched appropriately.

[0069] According to the inventor's trials, even when the uncoated portion is stretched using an EPS device, the boundary portion (or the portion where the protective layer is formed) is difficult to stretch. Here, the electrode sheet manufacturing apparatus 1 comprises a conveying device 102, a first press device 104, a second press device 106, and a stepped roll pressing device 108. The first press device 104 is located in the conveying path W1. The first press device 104 is a device that roll-presses the unformed portion 12a of the electrode sheet 10 with a pair of rubber rolls 30, 35. The second press device 106 is located downstream of the first press device 104 in the conveying path W1 and is a device that roll-presses the active material layer 14. The stepped roll pressing device 108 is located downstream of the second press device 106 in the conveying path W1 and is a device that applies tension to the unformed portion 12a of the electrode sheet 10 by pressing a stepped roll 50 against it. Of the pair of rubber rolls 30, 35, the upper roll 30 comprises a shaft 31 and an elastic body 32 wound around the shaft 31. In the upper roll 30, the diameter of the shaft 31 in the portion that presses the boundary portion 12d between the unformed portion 12a and the active material layer 14 (in this embodiment, the first portion 30a) is larger than the diameter of the shaft 31 in the portions that press outside the boundary portion 12d (in this embodiment, the second portion 30b and the third portion 30c). The thickness of the elastic body 32 in the portion that presses the boundary portion 12d is thinner than the thickness of the elastic body 32 in the portion that presses outside the boundary portion 12d.

[0070] In this electrode sheet manufacturing apparatus 1, the diameter of the shaft 31 is increased and the thickness of the elastic body 32 is reduced in the area where the boundary portion 12d is pressed. As a result, in the first press device 104, the boundary portion 12d, which is difficult to stretch in a normal EPS device, is easily stretched along the conveying direction. Furthermore, the active material layer 14 is pressed in the second press device 106, and the formed portion 12b is stretched. After that, the boundary portion 12d is further stretched by the stepped roll pressing device 108. As a result, the overall stretching of the current collector 12 is more uniform. Consequently, the tabs are more easily processed in subsequent processes. In addition, damage to the electrode sheet 10 that may occur due to uneven stretching of the current collector 12 in the width direction is more easily prevented.

[0071] Although the upper roll 30 has the configuration described above, it is not limited to this configuration. The configuration of the upper roll 30 described above may also be provided on the lower roll 35. Furthermore, the configuration of the upper roll 30 described above may be provided on both the upper roll 30 and the lower roll 35. Furthermore, the configuration of the upper roll 30 described above may be provided on the lower roll 35, and the configuration of the lower roll 35 described above may be provided on the upper roll. In other words, the upper roll 30 and the lower roll 35 described above may be provided in an inverted position.

[0072] Furthermore, the inventors have found that in order to stretch the boundary portion, it was necessary to increase the press pressure of the EPS device or increase the tension applied to the electrode sheet before and after the EPS device. However, when the press pressure of the EPS device is increased, the frictional force of the pair of rubber rolls constituting the EPS device increases, and the amount of deformation also increases. As a result, heat is easily applied to the pair of rubber rolls, and the rubber rolls deteriorate easily. In addition, the inventors have found that when a stepped roll is pressed against an uncoated area in order to stretch the boundary portion locally, the electrode sheet is prone to breaking.

[0073] Here, the tension applied to the uncoated portion 12a when the stepped roll 50 is pressed against it is set to be less than the tension applied to the uncoated portion 12a before and after the pair of rubber rolls 30 and 35. The electrode sheet 10 is set to a relatively high value before and after the pair of rubber rolls 30 and 35 that constitute the first press device 104 (EPS device). As a result, the boundary portion 12d of the uncoated portion 12a is stretched. Because the boundary portion 12d of the uncoated portion 12a is stretched, even if the tension applied to the uncoated portion 12a is reduced when the stepped roll 50 is pressed against it, the elongation of the boundary portion 12d can be easily adjusted appropriately. Furthermore, by reducing the tension applied to the uncoated portion 12a when the stepped roll 50 is pressed against it, the uncoated portion 12a becomes less susceptible to damage, and the risk of the electrode sheet 10 breaking can be reduced.

[0074] The technologies disclosed herein have been described in detail above. Unless otherwise specified, the embodiments and other details mentioned herein do not limit the present invention. Furthermore, the technologies disclosed herein can be modified in various ways, and each component and each process mentioned herein may be omitted or combined as appropriate, unless no particular problems arise. This specification also includes the disclosures described in the following sections.

[0075] Section 1: A manufacturing apparatus for producing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along the length direction at a predetermined position in the width direction of the current collector, and an active material layer formed on the part of the current collector excluding the unformed portion, A conveying device that conveys the electrode sheet along a predetermined conveying path, A first press device is arranged in the transport path and roll-presses the unformed portion of the electrode sheet with a pair of rubber rolls, In the aforementioned transport path, a second press device is positioned downstream of the first press device and roll-presses the active material layer, A stepped roll pressing device is positioned downstream of the second press device in the transport path and applies tension to the unformed portion of the electrode sheet by pressing a stepped roll against it. Equipped with, The stepped roll has a step in the portion of the unformed area that is at the boundary with the active material layer, and the diameter of the portion corresponding to the unformed area is larger than the diameter of the portion corresponding to the active material layer. At least one of the pair of rubber rolls comprises a shaft and an elastic body wound around the shaft. In at least one of the rubber rolls, The diameter of the shaft of the part that presses the boundary between the unformed portion and the active material layer is greater than the diameter of the shaft of the part that presses the area outside the boundary portion. The thickness of the elastic body in the part that presses the boundary portion is thinner than the thickness of the elastic body in the part that presses the area outside the boundary portion. Electrode sheet manufacturing equipment.

[0076] Section 2: The electrode sheet manufacturing apparatus according to item 1, wherein the tension applied to the unformed portion when the stepped roll is pressed against the unformed portion is less than the tension applied to the unformed portion before and after the pair of rubber rolls.

[0077] Section 3: The at least one of the rubber rolls is A first part that presses the boundary portion, The second and third parts press the area outside the aforementioned boundary portion. Equipped with, In the first part described above, the thickness of the elastic body is constant, In the second part, the elastic body gradually thickens outward from the end of the first part in the axial direction. The electrode sheet manufacturing apparatus according to item 1 or 2, wherein the third part has a constant thickness of elastic material extending axially outward from the end of the second part.

[0078] Section 4: The at least one of the rubber rolls is positioned such that its inner end corresponds to the end of the active material layer. The first portion covers the boundary portion, The length of the second portion is less than the width of the unformed portion. The electrode sheet manufacturing apparatus according to item 3, wherein the combined length of the first and second portions is 0.6 times or more and 0.85 times or less the overlapping width of the electrode sheet and at least one of the rubber rolls.

[0079] Section 5: The length over which at least one of the rubber rolls is pressed against at least one of the electrode sheet and the other rubber roll is: An electrode sheet manufacturing apparatus according to item 3 or 4, wherein the width of the unformed portion is 1.2 times or more and 2.1 times or less of the width pressed by the pair of rubber rolls.

[0080] Item 6: The electrode sheet manufacturing apparatus according to item 5, wherein in the second portion, the elastic body is inclined at an angle of 10 degrees or more and 25 degrees or less such that it becomes thicker axially outward from the end of the first portion.

[0081] Section 7: An electrode sheet manufacturing apparatus according to item 5 or 6, wherein the thickness of the elastic body in the third portion is 1.3 times or more and 2.0 times or less the thickness of the elastic body in the first portion.

[0082] Section 8: A method for manufacturing an electrode sheet comprising a current collector made of a long metal foil, an unformed portion set along the length direction at a predetermined position in the width direction of the current collector, and an active material layer formed on the part of the current collector excluding the unformed portion, While transporting the electrode sheet along a predetermined transport route, A first pressing step involves roll-pressing the unformed portion of the electrode sheet with a pair of rubber rolls, A second pressing step is performed after the first pressing step, in which the active material layer is roll-pressed, A stepped roll pressing step is performed after the second pressing step by pressing a stepped roll against the unformed portion of the electrode sheet to apply tension. Includes, The stepped roll has a step in the portion of the unformed area that is at the boundary with the active material layer, and the diameter of the portion corresponding to the unformed area is larger than the diameter of the portion corresponding to the active material layer. At least one of the pair of rubber rolls comprises a shaft and an elastic body wound around the shaft. In at least one of the rubber rolls, The diameter of the shaft of the part that presses the boundary between the unformed portion and the active material layer is greater than the diameter of the shaft of the part that presses the area outside the boundary portion. The thickness of the elastic body in the part that presses the boundary portion is thinner than the thickness of the elastic body in the part that presses the area outside the boundary portion. A method for manufacturing electrode sheets.

[0083] Section 9: The method for manufacturing an electrode sheet according to item 8, wherein in the step of pressing the stepped roll against the unformed portion, the tension applied to the unformed portion when the stepped roll is pressed against the unformed portion is made smaller than the tension applied to the unformed portion before and after the pair of rubber rolls.

[0084] Section 10: The at least one of the rubber rolls is A first part that presses the boundary portion, The second and third parts press the area outside the aforementioned boundary portion. Equipped with, In the first part described above, the thickness of the elastic body is constant, In the second part, the elastic body gradually thickens outward from the end of the first part in the axial direction. The method for manufacturing an electrode sheet according to item 8 or 9, wherein the third part has a constant thickness of elastic material extending axially outward from the end of the second part.

[0085] Section 11: The at least one of the rubber rolls is positioned such that its inner end corresponds to the end of the active material layer. The first portion covers the boundary portion, The length of the second portion is less than the width of the unformed portion. The method for manufacturing an electrode sheet according to item 10, wherein the combined length of the first and second portions is 0.6 times or more and 0.85 times or less the overlapping width of the electrode sheet and at least one of the rubber rolls.

[0086] Section 12: The length over which at least one of the rubber rolls is pressed against at least one of the electrode sheet and the other rubber roll is: A method for manufacturing an electrode sheet according to item 10 or 11, wherein the width of the unformed portion is 1.2 times or more and 2.1 times or less the width pressed by the pair of rubber rolls.

[0087] Section 13: The method for manufacturing an electrode sheet according to item 12, wherein in the second portion, the elastic body is inclined at an angle of 10 degrees or more and 25 degrees or less such that it becomes thicker axially outward from the end of the first portion.

[0088] Section 14: A method for manufacturing an electrode sheet according to item 12 or 13, wherein the thickness of the elastic body in the third portion is 1.3 times or more and 2.0 times or less the thickness of the elastic body in the first portion. [Explanation of symbols]

[0089] 1. Electrode sheet manufacturing apparatus 10 electrode sheets 12 Current collector 12a Uncoated area (unformed area) 12b Coating section (forming section) 12c protective layer 12d Boundary part 14 Active material layer 30 Top Roll 30a Part 1 30b 2nd part 30c 3rd part 30d Inner edge 30e outer edge 31, 36 axes 31a Part 1 31b Part 2 31c Part 3 32,37 Elastic body 32 Elastic body 32a Part 1 32b Part 2 32c 3rd part 33 End 33a Slope 35 Lower Roll 41, 42 Rolls (rolling rolls) 50-section roll 51 parts 51a Step 51a1 Slope 52,53 parts 54-59 Guide Roll 61, 62 Tension Roll 100 Roll Press Unit 102 Conveying device 104 First Pressing Machine 106 Second Pressing Machine 108-stage roll pressing device 110 Control device

Claims

1. A manufacturing apparatus for producing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along the length direction at a predetermined position in the width direction of the current collector, and an active material layer formed on the part of the current collector excluding the unformed portion, A conveying device that conveys the electrode sheet along a predetermined conveying path, A first press device is arranged in the transport path and roll-presses the unformed portion of the electrode sheet with a pair of rubber rolls, In the aforementioned transport path, a second press device is positioned downstream of the first press device and roll-presses the active material layer, In the aforementioned transport path, a stepped roll pressing device is positioned downstream of the second press device and applies tension by pressing a stepped roll against the unformed portion of the electrode sheet, and Equipped with, The stepped roll has a step in the portion of the unformed area that is at the boundary with the active material layer, and the diameter of the portion corresponding to the unformed area is larger than the diameter of the portion corresponding to the active material layer. At least one of the pair of rubber rolls comprises a shaft and an elastic body wound around the shaft. In at least one of the rubber rolls, The diameter of the shaft of the part that presses the boundary between the unformed portion and the active material layer is greater than the diameter of the shaft of the part that presses the area outside the boundary portion. The thickness of the elastic body in the part that presses the boundary portion is thinner than the thickness of the elastic body in the part that presses the area outside the boundary portion. Electrode sheet manufacturing equipment.

2. The electrode sheet manufacturing apparatus according to claim 1, wherein the tension applied to the unformed portion when the stepped roll is pressed against the unformed portion is less than the tension applied to the unformed portion before and after the pair of rubber rolls.

3. The at least one of the rubber rolls is A first part that presses the boundary portion, The second and third parts press the area outside the aforementioned boundary portion. Equipped with, In the first part described above, the thickness of the elastic body is constant, In the second portion, the elastic body gradually thickens outward from the end of the first portion, The electrode sheet manufacturing apparatus according to claim 1 or 2, wherein the third portion has a constant thickness of elastic material extending axially outward from the end of the second portion.

4. The at least one of the rubber rolls is positioned such that its inner end corresponds to the end of the active material layer. The first portion covers the boundary portion, The length of the second portion is smaller than the width of the unformed portion. The electrode sheet manufacturing apparatus according to claim 3, wherein the combined length of the first portion and the second portion is 0.6 times or more and 0.85 times or less the width over which the electrode sheet and at least one of the rubber rolls overlap.

5. The length over which at least one of the rubber rolls is pressed against at least one of the electrode sheet and the other rubber roll is: The electrode sheet manufacturing apparatus according to claim 3, wherein the width of the unformed portion is 1.2 times or more and 2.1 times or less of the width pressed by the pair of rubber rolls.

6. The electrode sheet manufacturing apparatus according to claim 5, wherein in the second portion, the elastic body is inclined at an angle of 10 degrees or more and 25 degrees or less such that it becomes thicker axially outward from the end of the first portion.

7. The electrode sheet manufacturing apparatus according to claim 5, wherein the thickness of the elastic body in the third portion is 1.3 times or more and 2.0 times or less the thickness of the elastic body in the first portion.

8. A method for manufacturing an electrode sheet comprising a current collector made of a long metal foil, an unformed portion set along the length direction at a predetermined position in the width direction of the current collector, and an active material layer formed on the part of the current collector excluding the unformed portion, While transporting the electrode sheet along a predetermined transport route, A first pressing step involves roll-pressing the unformed portion of the electrode sheet with a pair of rubber rolls, A second pressing step is performed after the first pressing step, in which the active material layer is roll-pressed, A stepped roll pressing step is performed after the second pressing step by pressing a stepped roll against the unformed portion of the electrode sheet to apply tension. Includes, The stepped roll has a step in the portion of the unformed area that is at the boundary with the active material layer, and the diameter of the portion corresponding to the unformed area is larger than the diameter of the portion corresponding to the active material layer. At least one of the pair of rubber rolls comprises a shaft and an elastic body wound around the shaft. In at least one of the rubber rolls, The diameter of the shaft of the part that presses the boundary between the unformed portion and the active material layer is greater than the diameter of the shaft of the part that presses the area outside the boundary portion. The thickness of the elastic body in the part that presses the boundary portion is thinner than the thickness of the elastic body in the part that presses the area outside the boundary portion. A method for manufacturing electrode sheets.

9. The method for manufacturing an electrode sheet according to claim 8, wherein in the step of pressing the stepped roll against the unformed portion, the tension applied to the unformed portion when the stepped roll is pressed against the unformed portion is made smaller than the tension applied to the unformed portion before and after the pair of rubber rolls.

10. The at least one of the rubber rolls is A first part that presses the boundary portion, The second and third parts press the area outside the aforementioned boundary portion. Equipped with, In the first part described above, the thickness of the elastic body is constant, In the second portion, the elastic body gradually thickens outward from the end of the first portion, The method for manufacturing an electrode sheet according to claim 8 or 9, wherein the third portion has a constant thickness of elastic material extending axially outward from the end of the second portion.

11. The at least one of the rubber rolls is positioned such that its inner end corresponds to the end of the active material layer. The first portion covers the boundary portion, The length of the second portion is smaller than the width of the unformed portion. The method for manufacturing an electrode sheet according to claim 10, wherein the combined length of the first portion and the second portion is 0.6 times or more and 0.85 times or less the width of the overlap between the electrode sheet and at least one of the rubber rolls.

12. The length over which at least one of the rubber rolls is pressed against at least one of the electrode sheet and the other rubber roll is: A method for manufacturing an electrode sheet according to claim 10, wherein the width of the unformed portion is 1.2 times or more and 2.1 times or less the width pressed by the pair of rubber rolls.

13. The method for manufacturing an electrode sheet according to claim 12, wherein in the second portion, the elastic body is inclined at an angle of 10 degrees or more and 25 degrees or less such that it becomes thicker axially outward from the end of the first portion.

14. The method for manufacturing an electrode sheet according to claim 12, wherein the thickness of the elastic body in the third portion is 1.3 times or more and 2.0 times or less the thickness of the elastic body in the first portion.

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