Electrode sheet manufacturing device and method for manufacturing the same

Abstract

To suppress wrinkles occurring in an electrode sheet.SOLUTION: A method for manufacturing an electrode sheet 10 includes the stepped roll pressing step of conveying an electrode sheet 10, while pressing the electrode sheet 10 against a stepped roll 50, the stepped roll 50 having a part 51 corresponding to a boundary part 12d between an uncoated part 12a and an active material layer 14, and the diameter being locally larger than the diameter of parts 52 and 53 corresponding to other parts 12a and 12b of the electrode sheet 10.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2023-36089 discloses a method for manufacturing an electrode sheet having a coated portion on a metal foil where an active material layer containing an electrode material is coated, and an uncoated portion is set at the end of the coated portion. The manufacturing method disclosed in this publication discloses that when the electrode sheet is roll-pressed, the uncoated portion is pressed with a pair of elastic rolls. By pressing the uncoated portion with a pair of elastic rolls, it is possible to apply a compressive force and a deforming force to the same location on the uncoated portion. This is said to enable the uncoated portion to be stretched while suppressing breakage of the uncoated portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-36089 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the present inventors have found that when an electrode sheet is roll-pressed, wrinkles may occur in the electrode sheet even when the uncoated portion is pressed with a pair of elastic rolls. [Means for solving the problem]

[0005] The electrode sheet manufacturing apparatus disclosed herein is an apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along the length of the current collector at a predetermined position in the width direction, and an active material layer formed on the current collector in a portion excluding the unformed portion. The electrode sheet manufacturing apparatus includes a roll press unit that roll-presses the electrode sheet. The roll press unit includes a conveying device that conveys the electrode sheet along a predetermined conveying path, and a stepped roll pressing device that is disposed on the conveying path and presses a stepped roll against the electrode sheet. The stepped roll has a diameter locally larger at a portion of the unformed portion that corresponds to the boundary with the active material layer than at a portion that corresponds to other portions of the electrode sheet.

[0006] This electrode sheet manufacturing apparatus can suppress wrinkles in the electrode sheet caused by the difference in elongation rate of the current collector between the boundary portion with the active material layer in the unformed portion and the other portions.

[0007] The method for manufacturing an electrode sheet disclosed herein relates to a method for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along the length of the current collector at a predetermined position in the width direction, and an active material layer formed on the current collector except for the unformed portion.The method includes a stepped roll pressing step in which the electrode sheet is conveyed while being pressed against a stepped roll in which the diameter of the unformed portion at the boundary with the active material layer is locally larger than the diameter of the other portions of the electrode sheet.

[0008] According to this method for manufacturing an electrode sheet, it is possible to provide an electrode sheet in which wrinkles caused by the difference in elongation rate of the current collector between the boundary part with the active material layer in the unformed part and the other part can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow diagram of the manufacturing method for an electrode sheet. [Figure 2] FIG. 2 is a schematic diagram of the electrode sheet 10. [Figure 3]FIG. 3 is a schematic diagram showing another embodiment of the electrode sheet 10. In FIG. [Figure 4] FIG. 4 is a schematic diagram showing an example of the roll press step S6 proposed here. [Figure 5] FIG. 5 is a schematic diagram of the first pressing step S6a. [Figure 6] FIG. 6 is a schematic diagram of the stepped roll pressing step S6c. [Figure 7] FIG. 7 is a schematic diagram showing another embodiment of the method for producing an electrode sheet. [Figure 8] FIG. 8 is a schematic diagram showing another embodiment of the method for producing the electrode sheet 10. In FIG. [Figure 9] FIG. 9 is a schematic diagram showing a stepped roll 50A. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiments described herein are, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations are appropriately omitted. In this specification, expressions such as "X to Y" that indicate a numerical range mean "X or more and Y or less," unless otherwise specified.

[0011] Fig. 1 is a flow diagram of the manufacturing method of an electrode sheet. As shown in Fig. 1, the manufacturing method of an electrode sheet includes a conveying step S1, a measuring step S2, a kneading step S3, a coating step S4, a drying step S5, and a roll pressing step S6. However, the manufacturing method of an electrode sheet may include other steps.

[0012] <Electrode sheet 10> 2 is a schematic diagram of an electrode sheet 10. The electrode sheet 10 constitutes the positive electrode sheet or negative electrode sheet of an electrode body housed inside an electricity storage device. An electricity storage device refers to a device that can be repeatedly charged and discharged, and is a concept that encompasses so-called storage batteries (i.e., chemical batteries) such as lithium ion secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and other such batteries, as well as capacitors (i.e., physical batteries) such as electric double layer capacitors.

[0013] As shown in FIG. 2 , the electrode sheet 10 includes a current collector 12 and an active material layer 14. The current collector 12 is a member made of metal foil. The current collector 12 is a long, strip-shaped metal member. A metal material having a required conductivity can be used for the current collector 12. For example, aluminum or an aluminum alloy can be used for the positive electrode current collector foil. For example, copper or a copper alloy can be used for the negative electrode current collector foil. The active material layer 14 is coated at a predetermined position on 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 an electrode active material. For example, a lithium transition metal composite oxide can be used for the positive electrode active material. For example, a carbon material, a silicon-based material, or a mixed oxide thereof can be used for the negative electrode active material. The active material layer may contain additives other than the electrode active material, such as a binder and a conductive material.

[0014] The electrode sheet 10 is formed by applying an electrode mixture slurry that will become the active material layer 14 to a current collector 12 and drying the applied slurry. The current collector 12 has uncoated portions 12a (unformed portions) and coated portions 12b. The uncoated portions 12a are portions of the current collector 12 that are not coated with the active material layer 14. The uncoated portions 12a are set along the length of the ends in the width direction of the electrode sheet 10. In this embodiment, the uncoated portions 12a are set at both ends in the width direction of the electrode sheet 10. The coated portions 12b are arranged between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode mixture slurry is applied to the coated portions 12b. As a result, 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 arranged between the uncoated portions 12a at both ends in the width direction of the electrode sheet 10. In this way, the electrode sheet preferably has a current collector 12 made of a long metal foil, an unformed portion (here, an uncoated portion 12a) set along the length of the current collector 12 at a predetermined position in the width direction, and an active material layer 14 formed on the current collector 12 in a portion other than the unformed portion.

[0015] FIG. 3 is a schematic diagram illustrating another embodiment of the electrode sheet 10. As shown in FIG. 3, the electrode sheet 10 may have an insulating protective layer 12c in the uncoated portion 12a adjacent to the coated portion 12b. This structure may be employed, for example, in an electrode sheet 10 used for a positive electrode. The provision of this protective layer 12c on an electrode sheet 10 used for a positive electrode can prevent short circuits between the positive electrode current collector foil and the negative electrode active material layer. The protective layer 12c contains an insulating inorganic filler. An example of the inorganic filler is insulating particles, such as ceramic particles of alumina. The protective layer 12c may contain, for example, a binder. The binder may be the same as the binder exemplified as one that may be contained in the positive electrode active material layer. Hereinafter, unless otherwise specified, reference will be made to FIGS. 2 and 3 for the components of the electrode sheet 10, as appropriate.

[0016] <Transportation process S1, measurement process S2, kneading process S3, coating process S4, drying process S5> In a conveying step S1 shown in FIG. 1, the electrode sheet 10 is conveyed. In the conveying step S1, the electrode sheet 10 is conveyed along a predetermined conveying path W1. In a weighing step S2, raw materials for the active material layer 14 (see FIG. 2) are weighed. The weighing can be achieved, for example, by a weighing device (not shown) having a balance, a load cell, or the like. The weighed raw materials for the active material layer 14 are mixed in a kneading step S3. The kneading step S3 can be achieved by a kneading device (not shown). The raw materials for the active material layer 14, which have been made into a slurry by the kneading device, are applied to the current collector 12 (see FIG. 2) in a coating step S4. The coating step S4 can be achieved by a coating device (not shown), such as a slit coater, gravure coater, die coater, or comma coater. In a drying step S5, the applied raw materials for the active material layer 14 in a slurry state are dried. The drying step S5 can be achieved by, for example, a drying device (not shown) that emits hot air or infrared rays.

[0017] <Roll press process S6> The roll pressing step S6 is a step of roll pressing the electrode sheet 10. Here, the substrate of the electrode sheet 10 is a metal foil. The electrode sheet 10 has a portion where the active material layer 14 is formed (coated portion 12b) and a portion where the active material layer 14 is not formed (uncoated portion 12a). The main purpose of the roll pressing step S6 is to adjust the active material layer 14 formed by coating to an appropriate density.

[0018] In the roll pressing step S6, the coated portion 12b is roll pressed to achieve an appropriate density for 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 the pressure of the press is not directly transmitted to the uncoated portion 12a, making it difficult for the current collector 12 of the substrate to stretch. Therefore, if only the coated portion 12b is pressed, the elongation of the current collector 12 may vary between the coated portion 12b and the uncoated portion 12a. Large variations in the elongation of the current collector 12 between the coated portion 12b and the uncoated portion 12a may cause wrinkles to form in the electrode sheet 10. The uncoated portion 12a is cut into a predetermined shape in a subsequent process to form a tab. At this time, if wrinkles occur at the boundary portion 12d of the uncoated portion 12a with the active material layer 14, the tab may not be formed in the appropriate shape.

[0019] To prevent wrinkles from forming in the electrode sheet 10, it is preferable to stretch the current collector 12 with the uncoated portion 12a before or after roll-pressing the coated portion 12b. One technique for stretching the current collector 12 with 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, an apparatus for pressing the uncoated portion 12a with a rubber roll may be appropriately referred to as an EPS apparatus.

[0020] The present inventors have discovered that wrinkles occur in the electrode sheet 10 even when the uncoated portions 12a are stretched by EPS before and after roll pressing. Wrinkles occur particularly at boundary portions 12d of the uncoated portions 12a where the uncoated portions 12a meet the active material layer 14. The present inventors have discovered that this phenomenon is caused by the fact that, when the uncoated portions 12a are stretched by EPS, boundary portions 12d of the uncoated portions 12a where the uncoated portions meet the active material layer 14 cannot be properly stretched.

[0021] That is, an active material layer 14 is formed on 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. Pressing the EPS rubber roll against the active material layer 14 can cause the active material layer 14 to peel off. From this perspective, the position of the rubber roll in the EPS is set so that it does not come into contact with the coated portion 12b. As a result, the boundary between the uncoated portion 12a and the coated portion 12b and the surrounding area are less likely to be stretched in the EPS. 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. If a protective layer is formed, when the EPS rubber roll is pressed against the active material layer, the elongation percentage may not be the same between the area where the protective layer is formed and the area where the protective layer is not formed.

[0022] Thus, when uncoated portion 12a is stretched with EPS, it is difficult to properly stretch boundary portion 12d of uncoated portion 12a with active material layer 14. As a result, the inventors believe that distortion remains in boundary portion 12d, causing wrinkles in the electrode sheet.

[0023] Fig. 4 is a schematic diagram showing an example of the roll pressing process S6 proposed herein. As shown in Fig. 4, the roll pressing process S6 includes a first pressing process S6a, a second pressing process S6b, and a stepped roll pressing process S6c.

[0024] The first pressing step S6a is the above-mentioned EPS, and is a step of stretching the uncoated portion 12a of the electrode sheet 10. Fig. 5 is a schematic diagram of the first pressing step S6a. As shown in Fig. 5, the first pressing step S6a is a step of pressing and stretching the uncoated portion 12a of the electrode sheet 10 with a pair of rubber rolls 30 while transporting the electrode sheet 10 along a predetermined transport path.

[0025] As shown in FIG. 5 , the rubber roll 30 is preferably a roll member in which an elastic body 32 is disposed on the outer peripheral surface of a shaft 31. The elastic body 32 used in the rubber roll 30 is preferably an elastic material having a required Young's modulus. Examples of the elastic body 32 include rubber and resins such as urethane. In the first pressing step S6a, the uncoated portion 12a is pressed by the rubber roll 30, and receives a reaction force from the elastic deformation and compressive deformation of the rubber roll, pressing and pulling the portion pressed by the roll. In the first pressing step S6a, the uncoated portion 12a can be stretched without applying a large tension to the electrode sheet 10.

[0026] As shown in FIG. 4, the second pressing step S6b is a step of roll-pressing the active material layer 14 (coated portion 12b) of the electrode sheet 10. This step adjusts the active material layer 14 (coated portion 12b) to a required density. In the second pressing step S6b, as shown in FIG. 4, the electrode sheet 10 is sandwiched between a pair of rolls 41, 42, and the active material layer 14 is compressed. During this process, the current collector 12, which is the substrate, is stretched in the area where the active material layer 14 is formed (coated portion 12b).

[0027] The stepped roll pressing step S6c is a step of locally stretching current collector 12, which is the substrate, at boundary portion 12d (see FIGS. 2 and 3) of uncoated portion 12a with active material layer 14. Fig. 6 is a schematic diagram of the stepped roll pressing step S6c.

[0028] <Stepped Roll 50> As shown in FIG. 6, the diameter of the stepped roll 50 used in step S6c is locally larger at a portion 51 of the uncoated portion 12a corresponding to the boundary 12d with the active material layer 14 than at other portions (a portion 52 corresponding to the active material layer 14 and a portion 53 corresponding to the uncoated portion 12a). In the configuration shown in FIG. 6, the diameter of the portion 51 of the uncoated portion 12a corresponding to the boundary 12d with the active material layer 14 is continuously and uniformly increased in the circumferential direction. As shown in FIG. 4, the electrode sheet 10 is transported while being wound around the stepped roll 50 with a required tension. This causes the boundary 12d between the active material layer 14 and the uncoated portion 12a to be pressed against the larger-diameter portion 51 of the stepped roll 50. This locally stretches the current collector 12 at the boundary 12d with the active material layer 14 in the uncoated portion 12a. Here, the boundary portion 12d of the uncoated portion 12a with the active material layer 14 can be the boundary or a region near the boundary between the active material layer 14 and the uncoated portion 12a of the electrode sheet 10.

[0029] Here, the boundary portion 12d between the active material layer 14 and the uncoated portion 12a is defined as a portion where the current collector 12, which is the substrate, is less likely to stretch in the first press step S6a in which the uncoated portion 12a is pressed and stretched, and in the second press step S6b in which the active material layer 14 is roll-pressed. The boundary portion 12d between the active material layer 14 and the uncoated portion 12a can be defined in accordance with 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, approximately 0 to 3 mm (e.g., approximately 2 mm). As shown in FIG. 3, a protective layer 12c may be formed on the boundary portion 12d between the active material layer 14 and the uncoated portion 12a.

[0030] The roll pressing step S6 includes the stepped roll pressing step S6c as described above. In the stepped roll pressing step S6c, the electrode sheet 10 is conveyed while being pressed against a stepped roll 50 in which the diameter of a portion 51 of the uncoated portion 12a corresponding to the boundary 12d with the active material layer 14 is locally larger than the diameter of the portion of the electrode sheet 10 corresponding to the other portions. The stepped roll pressing step S6c stretches the current collector 12 at the boundary 12d of the uncoated portion 12a with the active material layer 14 in the electrode sheet 10. Then, in addition to the stepped roll pressing step S6c, a process of stretching the uncoated portion 12a (first pressing step S6a) and a process of roll pressing the coated portion 12b of the electrode sheet 10 (second pressing step S6b) are performed. This makes it possible to suppress the difference in elongation of the current collector 12 between the boundary portion 12d with the active material layer 14 in the uncoated portion 12a and the other portions. As a result, it is possible to suppress wrinkles in the electrode sheet 10 caused by the difference in elongation rate of the current collector 12 between the boundary portion 12d with the active material layer 14 in the uncoated portion 12a and the other portions. In particular, it is possible to suppress wrinkles that occur in the boundary portion 12d with the active material layer 14 in the uncoated portion 12a.

[0031] <Electrode sheet manufacturing equipment 1> 4, an electrode sheet manufacturing apparatus 1 that embodies such an electrode sheet manufacturing method includes a roll press unit 100 that roll-presses a strip-shaped electrode sheet 10. The roll press unit 100 includes a conveying device 102, a first press device 102, a second press device 104, and a stepped roll pressing device 108.

[0032] <Conveyance device 102> The conveying device 102 is a device that conveys the electrode sheet 10 along a predetermined conveying path W1. Details of the conveying device 102 will be omitted, but it is preferable that the conveying device 102 is a device that conveys the electrode sheet 10 along the conveying path W1. Although not shown in the figures, the conveying device 102 may include a mechanism that feeds the electrode sheet 10 along the conveying path W1, guide rolls that feed the electrode sheet 10 along the conveying path W1, a tension adjustment mechanism that applies a required tension to the electrode sheet 10, and a mechanism that winds up the electrode sheet 10 that has been conveyed along the conveying path W1.

[0033] <Stepped roll pressing device 108> The stepped roll pressing device 108 is disposed on the conveying path W1 and presses the stepped roll 50 against the electrode sheet 10. As shown in FIG. 6, the diameter of a portion 51 of the stepped roll 50 corresponding to the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is locally larger than the diameter of portions of the stepped roll 50 corresponding to other portions of the electrode sheet 10. As shown in FIG. 4, the roll press unit 100 includes a first press device 104 that presses and stretches the uncoated portion 12a of the electrode sheet 10 with a rubber roll 30. The roll press unit 100 further includes a second press device 106 that is disposed downstream of the first press device 104 on the conveying path W1 and presses and stretches the active material layer 14 of the electrode sheet 10 with a roll press. Here, the arrow labeled W1 in FIG. 4 indicates the conveying direction of the conveying path W1.

[0034] As shown in FIG. 6 , the stepped roll pressing device 108 includes a stepped roll 50 in which the diameter of a portion 51 of the uncoated portion 12a corresponding to the boundary portion 12d with the active material layer 14 is locally larger than the diameter of portions of the electrode sheet 10 corresponding to other portions. The boundary portion 12d of the uncoated portion 12a with the active material layer 14 of the electrode sheet 10 is pressed against the locally larger diameter portion 51 of the stepped roll 50. For example, in the embodiment shown in FIG. 4 , guide rolls 56 and 57 are disposed upstream and downstream of the stepped roll 50. The electrode sheet 10 is guided by the guide rolls 56 and 57 and transported while being wound around the stepped roll 50. At this time, it is preferable that tension be applied to the electrode sheet 10 by the guide rolls 56 and 57 so that the electrode sheet 10 is pressed against the stepped roll 50. At this time, as shown in FIG. 6, it is preferable that a locally raised portion 51 of the stepped roll 50 is pressed against a boundary portion 12d of the uncoated portion 12a of the electrode sheet 10 at the boundary with the active material layer 14.

[0035] In this way, in the stepped roll pressing device 108, the current collector 12 is conveyed while being pressed against the boundary 12d of the uncoated portion 12a of the electrode sheet 10 where the current collector 12 meets the active material layer 14. This causes the current collector 12 to be locally stretched at the boundary 12d of the uncoated portion 12a where the current collector 12 meets the active material layer 14. Then, in addition to the stepped roll pressing step S6c, a process of stretching the uncoated portion 12a (first pressing step S6a) and a process of roll-pressing the coated portion 12b of the electrode sheet 10 (second pressing step S6b) are performed. This makes it possible to reduce the difference in elongation of the current collector 12 between the boundary 12d of the uncoated portion 12a where the current collector 12 meets the active material layer 14 and other portions. As a result, it is possible to suppress wrinkles in the electrode sheet 10 caused by the difference in elongation rate between the boundary portion 12d of the uncoated portion 12a with the active material layer 14 and other portions of the current collector 12. In particular, it is possible to suppress wrinkles that occur in the boundary portion 12d of the uncoated portion 12a with the active material layer 14.

[0036] Here, as described above, the treatment for stretching the uncoated portion 12a may be treatment using, for example, EPS. As described above, it is difficult to stretch the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 using EPS. In the electrode sheet manufacturing method and electrode sheet manufacturing apparatus 1 proposed here, the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is stretched by the stepped roll 50. From this perspective, the treatment for locally stretching the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 using the stepped roll 50 as described above is particularly useful when EPS is used for the treatment for stretching the uncoated portion 12a. Note that the treatment for stretching the uncoated portion 12a is not limited to EPS unless otherwise specified.

[0037] In the electrode sheet manufacturing method proposed here, the current collector 12 is locally stretched by a stepped roll 50 at a boundary 12d of the uncoated portion 12a with the active material layer 14. The process of locally stretching the current collector 12 at the boundary 12d is preferably performed together with the process of stretching the uncoated portion 12a and the process of roll-pressing the coated portion 12b of the electrode sheet 10. This makes it possible to reduce the difference in elongation of the current collector 12 between the boundary 12d with the active material layer 14 and other portions of the uncoated portion 12a. The electrode sheet manufacturing method proposed here can be incorporated into a battery manufacturing method.

[0038] As shown in Figure 4, according to the inventors' findings, it is preferable to perform the process of stretching the uncoated portion 12a (first press step S6a) before the process of stretching the coated portion 12b (second press step S6b). If the uncoated portion 12a is stretched more than the process of stretching the coated portion 12b (second press step S6b), wrinkles are less likely to occur when the coated portion 12b is stretched. It is preferable to perform the process of stretching the uncoated portion 12a (first press step S6a) using EPS as described above.

[0039] In the embodiment shown in Fig. 4, the stepped roll pressing step S6c is performed after the process of stretching the coated portion 12b (second pressing step S6b). As shown in Fig. 4, the electrode sheet manufacturing apparatus 1 preferably includes a first pressing device 104, a second pressing device 106, and a stepped roll pressing device 108, which are arranged in this order along the conveying direction of the conveying path W1.

[0040] In this case, the uncoated portion 12a is stretched first. After the coated portion 12b is stretched further, the stepped roll pressing step S6c locally stretches the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14. In this case, after the uncoated portion 12a is stretched and the coated portion 12b is stretched further, the distortion remaining in the current collector 12 locally at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is corrected by the stepped roll pressing step S6c. As a result, wrinkles are suppressed throughout the electrode sheet 10.

[0041] Fig. 7 is a schematic diagram showing another embodiment of the electrode sheet manufacturing method. In the embodiment shown in Fig. 7, the stepped roll pressing step S6c is performed before the process of stretching the uncoated portion 12a (first pressing step S6a). As shown in Fig. 7, the electrode sheet manufacturing apparatus 1 preferably includes a stepped roll pressing device 108, a first pressing device 104, and a second pressing device 106, which are arranged in this order along the conveying direction of the conveying path W1.

[0042] In this case, the stepped roll pressing step S6c first locally stretches the current collector 12 at the boundary 12d of the uncoated portion 12a with the active material layer 14. Next, the uncoated portion 12a is stretched, and then the coated portion 12b is stretched. In this case, while the current collector 12 at the boundary 12d of the uncoated portion 12a with the active material layer 14 is locally stretched, the uncoated portion 12a is stretched, and then the coated portion 12b is stretched. In this way, before the process of stretching the uncoated portion 12a and the coated portion 12b, the current collector 12 at the boundary 12d of the uncoated portion 12a with the active material layer 14 is locally stretched. This prevents wrinkles from forming in the electrode sheet 10 as a whole when the uncoated portion 12a and the coated portion 12b are stretched.

[0043] Fig. 8 is a schematic diagram showing another embodiment of the method for manufacturing the electrode sheet 10. In the embodiment shown in Fig. 8, the stepped roll pressing step S6c is performed after the first pressing step S6a and before the second pressing step S6b. As shown in Fig. 8, the electrode sheet manufacturing apparatus 1 preferably includes a first pressing device 104, a stepped roll pressing device 108, and a second pressing device 106, which are arranged in this order along the conveying direction of the conveying path W1.

[0044] In this case, the uncoated portion 12a is stretched in the first pressing step S6a, and then the stepped roll pressing step S6c locally stretches the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14. Then, the coated portion 12b is further stretched in the second pressing step S6b. In this case, the process of stretching the uncoated portion 12a stretches the uncoated portion 12a, and then locally stretches the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14. Then, the coated portion 12b is stretched. In this case, the electrode sheet 10 is stretched in stages from the outside, and wrinkles in the electrode sheet 10 as a whole are suppressed.

[0045] As described above, in the roll pressing step S6 of the electrode sheet 10, the order of the process of locally stretching the current collector 12 at the boundary portion 12d, the roll pressing of the electrode sheet 10, and the process of stretching the uncoated portion 12a may be reversed as appropriate.

[0046] For example, in FIG. 4 and the like, the first pressing step S6a (a step of pressing the uncoated portion 12a) is performed before the second pressing step S6b (a step of roll-pressing the active material layer 14), but this order is not limited thereto. The first pressing step S6a may be performed (i) before the second pressing step S6b, or (ii) after the second pressing step S6b. Furthermore, the first pressing step S6a may be performed both before and after the second pressing step S6b (iii). The stepped roll pressing step S6c described above may be performed at any position among (i) to (iii), such as upstream or downstream of the first pressing step S6a, or upstream or downstream of the second pressing step S6b.

[0047] <Stepped roll 50A> FIG. 9 is a schematic diagram showing a stepped roll 50A. The stepped roll 50A is another form of the stepped roll 50 used in the stepped roll pressing step S6c. In the example shown in FIG. 9, the stepped roll 50A has a portion 51 of the uncoated portion 12a corresponding to the boundary portion 12d with the active material layer 14, which is raised toward the center 51a in the axial direction. More specifically, in the example shown in FIG. 9, the center is raised symmetrically, as in a normal distribution. In this way, the portion 51 of the uncoated portion 12a corresponding to the boundary portion 12d with the active material layer 14 may be shaped so that it is raised toward the center in the width direction. The raised shape at the center in the axial direction eliminates a portion where the height changes suddenly, such as a step. This makes it possible to suppress the occurrence of wrinkles in the electrode sheet 10 due to the portion 51 where the diameter of the stepped roll 50A is locally increased.

[0048] In this case, the region 51 is not limited to a shape with a symmetrical central rise like a normal distribution, but may be raised in an arc shape. The center of the region 51 where the diameter is locally increased on the stepped roll 50A should be aligned with the widthwise center of the region where the current collector 12 is expected to be insufficiently elongated in the first press step S6a and the second press step S6b. From this perspective, the axial spacing of the region 51 where the diameter is locally increased on the stepped roll 50A should be set according to the width of the coated portion 12b of the electrode sheet 10 to be processed. Furthermore, the electrode sheet 10 should be transported relative to the stepped roll 50A so that the region where the elongation of the current collector 12 is expected to be insufficient is aligned with the widthwise center of the region 51 where the diameter is locally increased on the stepped roll 50A. From this perspective, the transport device 102 may incorporate a position adjustment mechanism for adjusting the position of the electrode sheet 10 relative to the stepped roll 50.

[0049] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0050] As described above, this specification includes the disclosures set forth in the following sections.

[0051] Section 1: 1. A manufacturing apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along a length direction of the current collector at a predetermined position in a width direction thereof, and an active material layer formed on a portion of the current collector excluding the unformed portion, a roll press unit that roll-presses the electrode sheet, The roll press unit is a conveying device that conveys the electrode sheet along a predetermined conveying path; a stepped roll pressing device that is disposed on the transport path and presses a stepped roll against the electrode sheet; Equipped with the stepped roll has a diameter of a portion of the unformed portion that corresponds to a boundary with the active material layer that is locally larger than a diameter of a portion of the unformed portion that corresponds to another portion of the electrode sheet; Electrode sheet manufacturing equipment.

[0052] Section 2: The roll press unit is a first press device that is disposed on the conveyance path and that presses and stretches an uncoated portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet with a roll press; Furthermore, The stepped roll pressing device is arranged in front of the upstream side of the first press device in the conveying path. Item 1. An electrode sheet manufacturing apparatus according to item 1.

[0053] Section 3: The roll press unit is a first press device that is disposed on the conveyance path and that presses and stretches an uncoated portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet with a roll press; Furthermore, The stepped roll pressing device is disposed on the conveying path downstream of the first press device and upstream of the second press device. Item 1. An electrode sheet manufacturing apparatus according to item 1.

[0054] Section 4: The roll press unit is a first press device that is disposed on the conveyance path and that presses and stretches an uncoated portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet with a roll press; Furthermore, The stepped roll pressing device is arranged on the downstream side of the second press device in the conveying path. Item 1. An electrode sheet manufacturing apparatus according to item 1.

[0055] Section 5: Item 2. The electrode sheet manufacturing apparatus according to item 1, wherein the unformed portion of the stepped roll is elevated in the axial direction toward the center thereof at a boundary with the active material layer.

[0056] Item 6: a current collector made of a long metal foil; an unformed portion set along a length direction at a predetermined position in a width direction of the current collector; an active material layer formed on a portion of the current collector excluding the unformed portion; A method for manufacturing an electrode sheet, comprising: a stepped roll pressing step of conveying the electrode sheet while pressing it against a stepped roll in which the diameter of a portion of the unformed portion that corresponds to a boundary with the active material layer is locally larger than the diameter of a portion of the unformed portion that corresponds to another portion of the electrode sheet, Manufacturing method of electrode sheet.

[0057] Section 7: a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step in the conveying path after the first pressing step, in which the active material layer of the electrode sheet is roll-pressed; Including, Item 7. The method for producing an electrode sheet according to Item 6, wherein the stepped roll pressing step is carried out before the first pressing step.

[0058] Section 8: a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step in which the active material layer of the electrode sheet is pressed and stretched by a roll press after the first pressing step in the conveying path; Including, Item 7. The method for producing an electrode sheet according to Item 6, wherein the stepped roll pressing step is performed after the first pressing step and before the second pressing step.

[0059] Section 9: a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step in the conveying path after the first pressing step, in which the active material layer of the electrode sheet is roll-pressed; Including, Item 7. The method for producing an electrode sheet according to Item 6, wherein the stepped roll pressing step is carried out after the second pressing step.

[0060] Section 10: Item 7. The method for producing an electrode sheet according to Item 6, wherein the stepped roll has a portion of the unformed portion that corresponds to the boundary with the active material layer that is raised toward the center in the axial direction.

[0061] Section 11 A method for manufacturing a battery, comprising the method according to any one of items 6 to 10. [Explanation of symbols]

[0062] 1. Electrode sheet manufacturing equipment 10 Electrode sheet 12 Current collector 12a Uncoated area (unformed area) 12b Coating Department 12c protective layer 12d Boundary part 14 Active material layer 30 rubber roll 31 axes 32 Elastic Body 41,42 Rolls 50,50A stepped roll 51: a portion of the uncoated portion 12a that corresponds to the boundary portion 12d with the active material layer 14 51a: Axial center of part 51 52: Part corresponding to the active material layer 14 53 Uncoated part 12a 56,57 Guide roll 100 Roll Press Unit 102 Transport device 104 First Press Device 106 Second press device 108 Stepped roll pressing device S1 Transport process S2 Weighing process S3 kneading process S4 Coating process S5 Drying process S6 Roll press process S6a: First pressing step (step of stretching the uncoated portion 12a of the electrode sheet 10) S6b Second pressing step (step of roll-pressing the active material layer 14 of the electrode sheet 10) S6c: Stepped roll pressing step (step of stretching the current collector 12 at the boundary portion 12d) W1 transport route

Claims

1. 1. A manufacturing apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along a length direction of the current collector at a predetermined position in a width direction thereof, and an active material layer formed on a portion of the current collector excluding the unformed portion, a roll press unit that roll-presses the electrode sheet, The roll press unit is a conveying device that conveys the electrode sheet along a predetermined conveying path; a stepped roll pressing device that is disposed on the transport path and presses a stepped roll against the electrode sheet; Equipped with the stepped roll has a diameter of a portion of the unformed portion that corresponds to a boundary with the active material layer that is locally larger than a diameter of a portion of the unformed portion that corresponds to another portion of the electrode sheet; Electrode sheet manufacturing equipment.

2. The roll press unit is a first press device disposed on the transport path and configured to press and stretch an unformed portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet by a roll press; Furthermore, The stepped roll pressing device is arranged in front of the upstream side of the first press device in the conveying path. The electrode sheet manufacturing device according to claim 1 .

3. The roll press unit is a first press device disposed on the transport path and configured to press and stretch an unformed portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet by a roll press; Furthermore, The stepped roll pressing device is disposed on the conveying path downstream of the first press device and upstream of the second press device. The electrode sheet manufacturing device according to claim 1 .

4. The roll press unit is a first press device disposed on the transport path and configured to press and stretch an unformed portion of the electrode sheet with a rubber roll; a second press device that is disposed on the transport path downstream of the first press device and that presses and stretches the active material layer of the electrode sheet by a roll press; Furthermore, The stepped roll pressing device is disposed on the downstream side of the second press device in the conveying path. The electrode sheet manufacturing device according to claim 1 .

5. The electrode sheet manufacturing apparatus according to claim 1 , wherein a portion of the unformed portion of the stepped roll that corresponds to a boundary with the active material layer is raised toward a center in the axial direction.

6. a current collector made of a long metal foil; an unformed portion set along a length direction at a predetermined position in a width direction of the current collector; an active material layer formed on a portion of the current collector excluding the unformed portion; A method for manufacturing an electrode sheet, comprising: a stepped roll pressing step of conveying the electrode sheet while pressing it against a stepped roll in which the diameter of a portion of the unformed portion that corresponds to a boundary with the active material layer is locally larger than the diameter of a portion of the unformed portion that corresponds to another portion of the electrode sheet, Manufacturing method of electrode sheet.

7. a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step of roll-pressing the active material layer of the electrode sheet after the first pressing step in the transport path; Including, The method for manufacturing an electrode sheet according to claim 6 , wherein the stepped roll pressing step is performed before the first pressing step.

8. a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step in which the active material layer of the electrode sheet is pressed and stretched by a roll press after the first pressing step in the conveying path; Including, The method for manufacturing an electrode sheet according to claim 6 , wherein the stepped roll pressing step is performed after the first pressing step and before the second pressing step.

9. a first pressing step of pressing and stretching an unformed portion of the electrode sheet with a rubber roll while transporting the electrode sheet along a predetermined transport path; a second pressing step of roll-pressing the active material layer of the electrode sheet after the first pressing step in the transport path; Including, The method for manufacturing an electrode sheet according to claim 6 , wherein the stepped roll pressing step is carried out after the second pressing step.

10. The method for producing an electrode sheet according to claim 6 , wherein the unformed portion of the stepped roll is raised toward the center in the axial direction at a boundary portion with the active material layer.

11. A method for manufacturing a battery, comprising the method according to any one of claims 6 to 10.

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