Electrode sheet manufacturing apparatus, electrode sheet manufacturing method, and battery manufacturing method

Abstract

The invention provides an electrode sheet manufacturing device, an electrode sheet manufacturing method and a battery manufacturing method, wherein wrinkles generated on an electrode sheet are inhibited. This method for manufacturing an electrode sheet (10) comprises: a first pressing step in which an uncoated portion (12a) of the electrode sheet is rolled by a rubber roll while the electrode sheet is being conveyed along a predetermined conveyance path; a step roller pressing step (S6c) in which, after the first pressing step, the electrode sheet is conveyed while being pressed against a step roller (50) having a step (51a) in a region (51) that comes into contact with a boundary portion (12d) with the active material layer (14) in the uncoated portion (12a), the diameter of a portion (52) that comes into contact with the uncoated portion (12a) being larger than that of a portion (53) that comes into contact with the active material layer (14); and a second pressing step in which the active material layer (14) in the electrode sheet is rolled by a rolling method after the step roll pressing step (S6c).

Description

Technical Field

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

[0002] Japanese Patent Application Publication No. 2023-36089 discloses a method for manufacturing an electrode sheet. This electrode sheet has a coated portion on a metal foil, coated with an active material layer containing electrode material, and an uncoated portion is provided at the end of the coated portion. In the manufacturing method disclosed in the same publication, the uncoated portion is pressed using a pair of elastic rollers during the rolling of the electrode sheet. By using the pair of elastic rollers to press the uncoated portion, compressive and deformable forces are applied to the same area of ​​the uncoated portion. This allows the uncoated portion to extend while simultaneously preventing breakage.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-36089

[0004] Furthermore, the inventors discovered that even when the uncoated portion is pressed by a pair of elastic rollers during the rolling of the electrode sheet, wrinkles still occur on the electrode sheet. Summary of the Invention

[0005] The electrode sheet manufacturing apparatus disclosed herein is an apparatus for manufacturing electrode sheets, the electrode sheet comprising: a current collector, which is composed of a strip of metal foil; an unformed portion, which is set at a predetermined position in the width direction of the current collector along its length direction; and an active material layer, which is formed in the current collector in the portion other than the unformed portion. The electrode sheet manufacturing apparatus includes a rolling unit for rolling the electrode sheet. The rolling unit includes: a conveying device for conveying the electrode sheet along a predetermined conveying path; a first pressing device disposed in the conveying path and pressing the unformed portion of the electrode sheet with a rubber roller; a stepped roller pressing device disposed in the conveying path and pressing the stepped roller onto the electrode sheet; and a second pressing device disposed downstream of the stepped roller conveying section in the conveying path and pressing the active material layer of the electrode sheet by rolling. The stepped roller has a step at the portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer.

[0006] According to this electrode manufacturing apparatus, it is possible to suppress wrinkles in the electrode sheet caused by the difference in elongation of the current collector in the unformed portion and the boundary portion with the active material layer and other portions.

[0007] The electrode sheet manufacturing method disclosed herein includes: a first pressing step, in which the electrode sheet is transported along a predetermined transport path while the unformed portion of the electrode sheet is rolled with a rubber roller; a stepped roller pressing step, in which, after the first pressing step, the electrode sheet is pressed against a stepped roller while being transported, wherein the stepped roller has a step at the portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion that contacts the unformed portion is larger than the portion that contacts the active material layer; and a second pressing step, in which, after the stepped roller pressing step, the active material layer of the electrode sheet is rolled by roller pressing.

[0008] According to the method for manufacturing this electrode sheet, an electrode sheet that suppresses wrinkles caused by the difference in elongation between the current collector at the boundary with the active material layer in the unformed portion and other portions can be provided. Furthermore, the method for manufacturing this electrode sheet can be used in the manufacturing process of a battery. Attached Figure Description

[0009] Figure 1 This is a flowchart of the manufacturing process for the electrode sheet.

[0010] Figure 2 This is a schematic diagram of electrode 10.

[0011] Figure 3 This is a schematic diagram showing another way of representing electrode sheet 10.

[0012] Figure 4 This is a schematic diagram illustrating an example of the rolling process S6 presented here.

[0013] Figure 5 This is a schematic diagram of the first pressurization process S6a.

[0014] Figure 6 This is a schematic diagram of the stepped roller pressing process S6c.

[0015] Explanation of reference numerals in the attached figures

[0016] 1…Electrode sheet manufacturing apparatus; 10…Electrode sheet; 12…Current collector; 12a…Uncoated portion (unformed portion); 12b…Coated portion; 12c…Protective layer; 12d…Boundary portion; 14…Active material layer; 30…Rubber roller; 31…Shaft; 32…Elastomer; 41, 42…Rollers; 50, 50A…Stepped rollers; 51…Part that contacts the boundary portion 12d of the uncoated portion 12a with the active material layer 14; 51a…Step; 51a1…Inclined surface; 52…Part that contacts the active material layer 14; 53…Part that contacts the uncoated portion 12a; 56, 57…Guide rollers; 10 0… Roller pressing unit; 102… Transport device; 104… First pressing device; 106… Second pressing device; 108… Stepped roller pressing device; S1… Transport process; S2… Metering process; S3… Mixing process; S4… Coating process; S5… Drying process; S6… Roller pressing process; S6a… First pressing process (process of elongating the uncoated portion 12a in the electrode sheet 10); S6b… Second pressing process (process of rolling the active material layer 14 in the electrode sheet 10); S6c… Stepped roller pressing process (process of elongating the current collector 12 in the boundary portion 12d); W1… Transport path. Detailed Implementation

[0017] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the accompanying drawings. The embodiments described herein are not intended to specifically limit the invention. The drawings are schematic depictions and do not necessarily reflect actual objects. Furthermore, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repeated descriptions are appropriately omitted. Unless otherwise specified, expressions such as "X to Y" indicating numerical ranges in this specification mean "X or more, Y or less".

[0018] Figure 1 This is a flowchart of the manufacturing process for the electrode sheet. For example... Figure 1 As shown, the method for manufacturing an electrode sheet includes a handling process S1, a metering process S2, a mixing process S3, a coating process S4, a drying process S5, and a rolling process S6. However, the method for manufacturing an electrode sheet may also include other processes.

[0019] <Electrode Plate 10>

[0020] Figure 2 This is a schematic diagram of electrode plate 10. Electrode plate 10 constitutes the positive or negative electrode plate of the electrode body housed inside the energy storage device. Energy storage device refers to a device that can be repeatedly charged and discharged. In addition to so-called storage batteries (i.e., chemical batteries) such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries, it also includes capacitors (i.e., physical batteries) such as electric double-layer capacitors.

[0021] like Figure 2As shown, the electrode sheet 10 includes a current collector 12 and an active material layer 14. The current collector 12 is a component made of metal foil. The current collector 12 is a long strip-shaped metal component. As the current collector 12, a metal material with the required conductivity can be used. As the positive electrode current collector foil, for example, aluminum, aluminum alloy, etc., can be used. As the negative electrode current collector foil, for example, copper, copper alloy, etc., can be used. The active material layer 14 is applied to a predetermined position in the current collector 12. The active material layer 14 is formed on at least one side 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. As the positive electrode active material, for example, a lithium transition metal composite oxide can be used. As the negative electrode active material, for example, carbon materials, silicon-based materials, and their mixed oxides can be used. The active material layer may also contain additives other than the electrode active material, such as binders and conductive materials.

[0022] An electrode composite material slurry, forming an active material layer 14, is applied to the current collector 12 and dried to form an electrode sheet 10. The current collector 12 has uncoated portions 12a (unformed portions) and coated portions 12b. The uncoated portions 12a are the parts of the current collector 12 where the active material layer 14 is not coated. The uncoated portions 12a are located at the ends of the electrode sheet 10 in the width direction and extend along the length direction. In this embodiment, the uncoated portions 12a are located at both ends of the electrode sheet 10 in the width direction. The coated portions 12b are disposed between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode composite material slurry is applied to the coated portions 12b. Thus, the active material layer 14 is formed in the coated portions 12b of the current collector 12. That is, the active material layer 14 is disposed between the uncoated portions 12a at both ends of the electrode sheet 10 in the width direction. Thus, the electrode sheet may have a current collector 12 made of a long strip of metal foil, an unformed portion (here, an uncoated portion 12a) set at a predetermined position in the width direction along the length direction in the current collector 12, and an active material layer 14 formed in the current collector 12 in the portion other than the unformed portion.

[0023] Figure 3 This is a schematic diagram illustrating another embodiment of electrode 10. (For example...) Figure 3As shown, an insulating protective layer 12c can be provided in the electrode sheet 10 at a position adjacent to the coated portion 12b in the uncoated portion 12a. This structure can be used, for example, in the electrode sheet 10 used for the positive electrode. By providing this protective layer 12c in the electrode sheet 10 used for the positive electrode, short circuits between the positive electrode current collector foil and the negative electrode active material layer can be prevented. This protective layer 12c contains an insulating inorganic filler. Examples of inorganic fillers include insulating particles, such as ceramic particles like alumina. The protective layer 12c may also contain an adhesive, for example. The adhesive may also be included in the positive electrode active material layer and is the same as the illustrated adhesive. Hereinafter, unless otherwise specifically mentioned, reference will be made to the constituent elements of the electrode sheet 10. Figure 2 and Figure 3 .

[0024] <Transportation process S1, Metering process S2, Mixing process S3, Coating process S4, Drying process S5>

[0025] exist Figure 1 In the transport process S1 shown, electrode sheet 10 is transported. In transport process S1, electrode sheet 10 is transported along a predetermined transport path W1. In the metering process S2, the active material layer 14 (see reference) is metered. Figure 2 The raw material is used for the active material layer 14. This measurement can be achieved, for example, by a balance or a metering device (not shown) with a pressure measuring element. The measured raw material of the active material layer 14 is mixed in the mixing step S3. The mixing step S3 can be achieved by a mixing device (not shown). In the coating step S4, the raw material of the active material layer 14, which has become a slurry after being mixed by the mixing device, is coated onto the current collector 12 (see reference). Figure 2 The coating process S4 can be performed, for example, by a slit coater, gravure coater, die coater, comma coater, or other coating apparatus (not shown). In the drying process S5, the raw material of the coated slurry-like active substance layer 14 is dried. The drying process S5 can be performed, for example, by a drying apparatus (not shown) that emits hot air or infrared radiation.

[0026] <Rolling process S6>

[0027] Rolling process S6 is a process of rolling the electrode sheet 10. Here, the substrate of the electrode sheet 10 is a metal foil. In the electrode sheet 10, there are 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 main purpose of rolling process S6 is to adjust the density of the active material layer 14 formed by coating to an appropriate level.

[0028] In the rolling process S6, the coating section 12b is rolled to achieve an appropriate density for the active material layer 14. If the coating section 12b is rolled, the current collector 12 of the substrate elongates in the coating section 12b, but in the uncoated section 12a, where the pressure is not directly transmitted, the current collector 12 of the substrate does not easily elongate. Therefore, if only the coating section 12b is under pressure, the elongation of the current collector 12 may deviate between the coating section 12b and the uncoated section 12a. If the deviation in the elongation of the current collector 12 between the coating section 12b and the uncoated section 12a is large, it may cause wrinkles to form on the electrode sheet 10. In a subsequent process, the uncoated section 12a is cut into a specified shape to form an electrode tab. At this time, if wrinkles form at the boundary portion 12d of the uncoated section 12a with the active material layer 14, the electrode tab may not be formed into an appropriate shape.

[0029] To prevent wrinkles from forming on the electrode sheet 10, the current collector 12 can be elongated in the uncoated portion 12a before or after rolling the coated portion 12b. One technique for elongating the current collector 12 in the uncoated portion 12a is to press the uncoated portion 12a with a rubber roller. This technique is appropriately called EPS (Elasticity Powered Stretching). Furthermore, the device for pressing the uncoated portion 12a with a rubber roller can be appropriately called an EPS device.

[0030] Furthermore, the inventors have discovered that even when the uncoated portion 12a is stretched using EPS before and after rolling, wrinkles still occur on the electrode sheet 10. These wrinkles particularly occur at the boundary portion 12d of the uncoated portion 12a with the active material layer 14. The inventors have found that this phenomenon is caused by the boundary portion 12d of the uncoated portion 12a with the active material layer 14 not being stretched appropriately when the uncoated portion 12a is stretched using EPS.

[0031] 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. If the rubber roller of the EPS is pressed against the active material layer 14, the active material layer 14 will peel off. From this point of view, in the EPS, the position of the rubber roller is set so that the rubber roller does not contact the coated portion 12b. As a result, in the EPS, it is not easy for the boundary between the uncoated portion 12a and the coated portion 12b and its vicinity to elongate. In addition, sometimes a protective layer containing inorganic fillers is formed at the boundary between the uncoated portion 12a and the coated portion 12b. When a protective layer is formed, when the rubber roller of the EPS is pressed, the elongation rate is sometimes inconsistent between the area where the protective layer is formed and the area where the protective layer is not formed.

[0032] Thus, when the uncoated portion 12a is stretched in the EPS, it is difficult to stretch the boundary portion 12d of the uncoated portion 12a with the active material layer 14 properly. The inventors believe that this will lead to residual deformation in the boundary portion 12d, thereby causing wrinkles in the electrode sheet.

[0033] Figure 4 This is a schematic diagram illustrating an example of the rolling process S6 presented here. For example... Figure 4 As shown, the rolling process S6 includes a first pressing process S6a, a second pressing process S6b, and a stepped roller pressing process S6c.

[0034] The first pressurization step S6a is the aforementioned EPS, which is a step to elongate the uncoated portion 12a in the electrode sheet 10. Figure 5 This is a schematic diagram of the first pressurization step S6a. (See diagram below.) Figure 5 As shown, the first pressurization process S6a is a process in which the electrode sheet 10 is transported along a predetermined transport path while the uncoated portion 12a of the electrode sheet 10 is calendered with a pair of rubber rollers 30.

[0035] like Figure 5 As shown, the rubber roller 30 is simply a roller component with an elastomer 32 mounted on the shaft 31. The elastomer 32 used in the rubber roller 30 can be an elastic material having the required Young's modulus. Examples of elastomers 32 include rubber, polyurethane, and other resins. In the first pressing step S6a, the uncoated portion 12a is pressed by the rubber roller 30, and is subjected to the reaction forces of the elastic deformation and compressive deformation of the rubber roller, resulting in the pressed and stretched portion. In the first pressing step S6a, the uncoated portion 12a can be elongated without applying large tension to the electrode sheet 10.

[0036] like Figure 4 As shown, the second pressing step S6b is a process of rolling the active material layer 14 (coating portion 12b) in the electrode sheet 10. This process adjusts the active material layer 14 (coating portion 12b) to the required density. In the second pressing step S6b, as... Figure 4 As shown, the electrode sheet 10 is held by a pair of rollers 41 and 42, compressing the active material layer 14. At this time, the current collector 12, which serves as the substrate, is calendered at the location where the active material layer 14 is formed (coating portion 12b).

[0037] The stepped roller pressing process S6c is performed on the boundary portion 12d between the uncoated portion 12a and the active material layer 14 (see reference). Figure 2 , Figure 3 The process of locally elongating the current collector 12, which is a substrate. Figure 6 This is a schematic diagram of the stepped roller pressing process S6c.

[0038] <Stepped roller 50>

[0039] In the stepped roller 50 used in process S6c, such as Figure 6 As shown, the portion 51 that contacts the boundary portion 12d of the uncoated portion 12a and the active material layer 14 has a step 51a. Furthermore, the diameter of the portion 52 that contacts the uncoated portion 12a is larger than the diameter of the portion 53 that contacts the active material layer 14. Figure 6 In the manner shown, the diameter of the portion 52 that contacts the uncoated portion 12a should be the same. The diameter of the portion 53 that contacts the active material layer 14 should also be the same.

[0040] Here, the boundary portion 12d between the uncoated portion 12a and the active material layer 14 can be the boundary between the active material layer 14 and the uncoated portion 12a of the electrode sheet 10, and the area near the boundary. The boundary portion 12d between the active material layer 14 and the uncoated portion 12a is defined as the portion of the current collector 12, which serves as the substrate, that is not easily elongated during the first pressing step S6a of calendering the uncoated portion 12a and the second pressing step S6b of rolling the active material layer 14. The boundary portion 12d between the active material layer 14 and the uncoated portion 12a can be determined according to the specifications of the electrode sheet 10 and its manufacturing process. The width of the boundary portion 12d between the active material layer 14 and the uncoated portion 12a can be, for example, about 3 to 7 mm (e.g., about 5 mm). Figure 3 As shown, a protective layer 12c may also be formed at the boundary 12d between the active material layer 14 and the uncoated portion 12a.

[0041] Step 51a is provided at the portion 51 that contacts the boundary portion 12d of the uncoated portion 12a and the active material layer 14. Figure 6 In the illustrated method, the height of step 51a is set to such that when the electrode sheet 10 is wound around the stepped roller 50 and transported, it can contact the boundary portion 12d of the uncoated portion 12a with the active material layer 14 and elongate it. From this point of view, the height of step 51a also depends on the specifications of the electrode sheet 10 (e.g., the thickness of the current collector 12, the thickness of the active material layer 14 in the coated portion 12b, etc.). When the current collector 12, which serves as the substrate for the electrode sheet 10, is, for example, a 12 μm thick aluminum foil, the tension applied to the electrode sheet 10 when it is wound around the stepped roller 50 and transported is 80 N to 200 N, for example, about 100 N.

[0042] Here, the height h1 of step 51a is defined as the radial distance of the stepped roller 50 from the portion that contacts the coated portion 12b to the portion that contacts the uncoated portion 12a. The height h1 of step 51a can be, for example, 0.50 mm or more and 1.50 mm or less. Step 51a is composed of an inclined surface 51a1 that is inclined in the same direction as the axial direction of the stepped roller 50. The inclination angle of the inclined surface 51a1 is, for example, 15 degrees or more and 45 degrees or less relative to the axial direction of the stepped roller 50, and preferably 30 degrees. In addition, the starting point and ending point of the inclined surface 51a1 can be rounded and chamfered, for example, it is preferable to perform rounding with R=0.5.

[0043] <Method for manufacturing electrode sheets>

[0044] like Figure 4 As shown, the manufacturing method of the electrode sheet 10 proposed here is performed in the order of the first pressing step S6a, the stepped roller pressing step S6c, and the second pressing step S6b. According to the manufacturing method of the electrode sheet 10 proposed here, firstly, the uncoated portion 12a of the electrode sheet 10 is elongated by the first pressing step S6a. Then, the current collector 12 in the uncoated portion 12a at the boundary portion 12d with the active material layer 14 is elongated by the stepped roller pressing step S6c. Then, the coated portion 12b is further elongated by the second pressing step S6b. In this case, for the electrode sheet 10, the uncoated portion 12a, the boundary portion 12d in the uncoated portion 12a with the active material layer 14, and the coated portion 12b are elongated in stages from the outside. Therefore, wrinkles caused by the difference in elongation of the current collector 12 in the uncoated portion 12a at the boundary 12d with the active material layer 14 and in other portions 12a and 12b are suppressed, and wrinkles in the electrode sheet 10 as a whole are suppressed.

[0045] In the first pressing step S6a, an EPS device can be used to press the uncoated portion 12a using a rubber roller 30. In this case, the position and pressing force of the rubber roller 30 in the EPS device can be adjusted so that the uncoated portion 12a is pressed by the rubber roller 30. Furthermore, the position of the electrode sheet 10 being transported toward the EPS device can be adjusted so that the position of the uncoated portion 12a is aligned with the rubber roller 30 of the EPS device. In the stepped roller pressing step S6c, the position of the electrode sheet 10 can be adjusted relative to the stepped roller 50 so that the step 51a of the stepped roller 50 contacts the boundary portion 12d of the uncoated portion 12a with the active material layer 14. In this embodiment, the portion of the stepped roller 50 that contacts the uncoated portion 12a is relatively thick. Therefore, in the stepped roller pressing step S6c, the uncoated portion 12a, which has been elongated in the first pressing step S6a, is supported by the stepped roller 50.

[0046] <Electrode manufacturing apparatus 1>

[0047] like Figure 4 As shown, the electrode sheet manufacturing apparatus 1, which embodies the method for manufacturing the electrode sheet, includes a rolling unit 100 for rolling the strip-shaped electrode sheet 10. The rolling unit 100 includes a conveying device 102, a first pressing device 104, a stepped roller pressing device 108, and a second pressing device 106.

[0048] <Transportation Device 102>

[0049] 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 are omitted, but it is simply a device that conveys the electrode sheet 10 along the conveying path W1. Although not shown in the figure, the conveying device 102 includes a mechanism for feeding the electrode sheet 10 along the conveying path W1, a guide roller for conveying the electrode sheet 10 along the conveying path W1, a tension adjustment mechanism for applying the required tension to the electrode sheet 10, and a mechanism for winding the electrode sheet 10 conveyed along the conveying path W1.

[0050] <First pressurization device 104>

[0051] The first pressurizing device 104 can be an EPS device composed of a rubber roller 30 as described above. In the EPS device, the position and pressure of the rubber roller 30 can be adjusted by pressing the uncoated portion 12a with the rubber roller 30. In addition, the electrode sheet manufacturing apparatus 1 can be equipped with a position adjustment device (not shown) to adjust the position of the electrode sheet 10 being transported toward the EPS device in a way that precisely aligns the uncoated portion 12a with the rubber roller 30 of the EPS device.

[0052] <Stepped roller pressing device 108>

[0053] The stepped roller pressing device 108 is a device disposed on the transport path W1 and presses the stepped roller 50 onto the electrode sheet 10. The shape of the stepped roller 50 is as described above. In the stepped roller pressing device 108, as... Figure 6 As shown, a step 51a is provided corresponding to the boundary portion 12d of the uncoated portion 12a of the electrode sheet 10 with the active material layer 14. Furthermore, the diameter of the portion 52 that contacts the uncoated portion 12a is larger than the diameter of the portion 53 that contacts the active material layer 14. In the stepped roller pressing device 108, the electrode sheet 10 is transported by adjusting its position so that the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is precisely aligned with the step 51a of the stepped roller 50. Therefore, a position adjustment device (not shown) for adjusting the position of the electrode sheet 10 can be provided in front of the stepped roller 50.

[0054] Thus, in the stepped roller pressing device 108, the portion 51 of the stepped roller 50 with the step 51a is pressed against the boundary portion 12d of the uncoated portion 12a of the electrode sheet 10, which is adjacent to the active material layer 14, while the electrode sheet is being transported. Here, the stepped roller pressing device 108 is positioned downstream of the first pressing device 104 (first pressing step S6a) that elongates the uncoated portion 12a. For the electrode sheet 10, after the uncoated portion 12a is elongated, the boundary portion 12d of the uncoated portion 12a, which is adjacent to the active material layer 14, is elongated by the step 51a of the stepped roller 50. Furthermore, for the stepped roller 50, the diameter of the portion 52 that contacts the uncoated portion 12a is larger than the diameter of the portion 53 that contacts the active material layer 14.

[0055] Therefore, with the uncoated portion 12a and the active material layer 14, which have been stretched by the first pressing device 104, properly supported on the stepped roller 50, the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is pressed against the step 51a of the stepped roller 50 for correction. Therefore, when the electrode sheet 10 is pressed against the stepped roller 50, the electrode sheet 10 is prone to breakage. Furthermore, after the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is stretched by the stepped roller pressing device 108, the coated portion 12b of the electrode sheet 10 is then subjected to a rolling process by the second pressing device 106 (second pressing step S6b). Thus, for the electrode sheet 10, the current collector 12 is elongated sequentially from the outside in the width direction, following the order of the uncoated portion 12a, the boundary portion 12d of the uncoated portion 12a with the active material layer 14, and the coated portion 12b. Therefore, the electrode sheet 10 as a whole is less prone to breakage and wrinkling.

[0056] Here, in the process of elongating the uncoated portion 12a (first pressing step S6a), as described above, for example, an EPS-based process can be used. As mentioned above, it is difficult to elongate 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 presented here, the current collector 12 at the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is elongated using a stepped roller 50. Therefore, in the second pressing step S6b, the coated portion 12b is rolled while the boundary portion 12d of the uncoated portion 12a with the active material layer 14 is elongated. In this case, when the coated portion 12b is rolled, wrinkles are less likely to occur at the boundary portion 12d of the uncoated portion 12a with the active material layer 14, and as a result, wrinkles are suppressed as a whole in the electrode sheet 10.

[0057] In addition, such as Figure 3 and Figure 6As shown, the boundary portion 12d is pressed against the step 51a of the stepped roller 50 to elongate it, so that even when a protective layer 12c is present in the boundary portion 12d with the active material layer 14 in the uncoated portion 12a, it will be properly elongated.

[0058] The electrode sheet 10 manufactured by this method generally suppresses wrinkles. This electrode sheet manufacturing method can be used for battery manufacturing.

[0059] The invention disclosed herein has been described in various ways above. Unless otherwise specified, the embodiments described herein are not intended to limit the invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and the constituent elements and processes mentioned herein can be appropriately omitted or combined as long as no particular problems arise.

[0060] As stated above, this specification includes the disclosures described below.

[0061] Item 1:

[0062] An electrode sheet manufacturing apparatus is provided for manufacturing electrode sheets. The electrode sheet includes: a current collector made of a strip of metal foil; an unformed portion set at a predetermined position in the width direction of the current collector along its length; and an active material layer formed in the current collector in the portion other than the unformed portion. The electrode sheet manufacturing apparatus includes a rolling unit for rolling the electrode sheet. The rolling unit includes: a transport device for transporting the electrode sheet along a predetermined transport path; a first pressing device disposed in the transport path and pressing the unformed portion of the electrode sheet with a rubber roller; a stepped roller pressing device disposed in the transport path and pressing the stepped roller onto the electrode sheet; and a second pressing device disposed downstream of the stepped roller transport portion in the transport path and pressing the active material layer of the electrode sheet by rolling. The stepped roller has a step at the portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion that contacts the unformed portion is larger than the diameter of the portion that contacts the active material layer.

[0063] Item 2:

[0064] According to the electrode sheet manufacturing apparatus described in item 1, the electrode sheet has a protective layer along the boundary between the active material layer and the unformed portion.

[0065] Item 3:

[0066] A method for manufacturing an electrode sheet, the electrode sheet comprising: a current collector composed of a strip of metal foil; an unformed portion set at a predetermined position in the width direction of the current collector along its length direction; and an active material layer formed in the current collector at a portion other than the unformed portion, wherein the method for manufacturing the electrode sheet includes: a first pressing step in which the electrode sheet is transported along a predetermined transport path while the unformed portion of the electrode sheet is rolled with a rubber roller; a stepped roller pressing step in which, after the first pressing step, the electrode sheet is pressed against a stepped roller while being transported, wherein the stepped roller has a step at a portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion that contacts the unformed portion is larger than the diameter of the portion that contacts the active material layer; and a second pressing step in which, after the stepped roller pressing step, the active material layer of the electrode sheet is rolled by a roller pressing method.

[0067] Item 4:

[0068] According to the method for manufacturing an electrode sheet as described in item 3, a protective layer is formed on the electrode sheet along the boundary between the active material layer and the unformed portion.

[0069] Item 5:

[0070] A method for manufacturing a battery, wherein the method comprises manufacturing an electrode sheet as described in item 3 or 4.

Claims

1. An electrode sheet manufacturing apparatus, comprising: a current collector composed of a strip of metal foil; an unformed portion disposed along the length direction at a predetermined position in the width direction of the current collector; and an active material layer formed in the current collector excluding the unformed portion, wherein... The electrode sheet manufacturing apparatus includes a rolling unit for rolling the electrode sheet. The roller pressing unit includes: A transport device transports the electrode sheet along a pre-determined transport path; A first pressurizing device is disposed in the transport path and uses a rubber roller to roll the unformed portion in the electrode sheet; A stepped roller pressing device is disposed in the conveying path and presses the stepped roller onto the electrode sheet; as well as The second pressurizing device is located downstream of the stepped roller conveying section in the conveying path, and rolls the active material layer in the electrode sheet by roller pressing. The stepped roller has a step at the portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion that contacts the unformed portion is larger than the diameter of the portion that contacts the active material layer.

2. The electrode sheet manufacturing apparatus according to claim 1, wherein, The electrode sheet has a protective layer along the boundary between the active material layer and the unformed portion.

3. A method for manufacturing an electrode sheet, wherein the electrode sheet comprises: The current collector is made of long strips of metal foil; The unformed portion is positioned along the length direction at a predetermined position in the width direction of the current collector; and An active material layer is formed in the current collector in the portion other than the unformed portion. in, The method for manufacturing the electrode sheet includes: In the first pressurization process, the electrode sheet is transported along a predetermined transport path while the unformed portion of the electrode sheet is rolled with a rubber roller. In the stepped roller pressing process, after the first pressing process, the electrode sheet is pressed onto a stepped roller while being transported. The stepped roller has a step at the portion that contacts the boundary between the unformed portion and the active material layer, and the diameter of the portion contacting the unformed portion is larger than the diameter of the portion contacting the active material layer. The second pressing process involves rolling the active material layer in the electrode sheet after the stepped roller pressing process.

4. The method for manufacturing the electrode sheet according to claim 3, wherein, The electrode sheet has a protective layer formed along the boundary between the active material layer and the unformed portion.

5. A method for manufacturing a battery, wherein, A method for manufacturing an electrode sheet as described in claim 3 or 4.

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