Method for processing electrode sheet and electrode sheet manufacturing apparatus

Abstract

To stabilize the elongation rate of an unformed part of an electrode sheet.SOLUTION: A method for processing an electrode sheet 10 according to the present embodiment includes a preparation step S101, a heat application step S102, and an elongation step S103. In the heat application step S102, the surface temperature of a pressing roll 62 is increased by a heat application control unit 101 until the surface temperature of the pressing roll 62 reaches or exceeds a reference temperature. The heat application step S102 is performed before execution of the elongation step S103. In the elongation step S103, an elongation control unit 104 elongates an uncoated part 12a (unformed part) by the pressing roll 62.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an electrode sheet processing method and an electrode sheet manufacturing apparatus. [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 the uncoated portion is pressed with a pair of elastic rolls (rubber rolls). By pressing the uncoated portion with the 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 inventors of the present application wish to suppress variations in the degree of stretching of uncoated portions (unformed portions). [Means for solving the problem]

[0005] The electrode sheet treatment method disclosed herein includes a preparation step of preparing a strip-shaped electrode sheet in which an electrode active material layer is applied to a current collector made of metal foil, the current collector having an unformed portion where the electrode active material layer is not formed; a stretching step of stretching the unformed portion of the electrode sheet by pressing a rubber roll against the unformed portion of the electrode sheet while transporting the strip-shaped electrode sheet; and a heat application step of applying heat to the rubber roll until the surface temperature of the rubber roll reaches or exceeds a predetermined reference temperature before the stretching step.

[0006] According to this electrode sheet processing method, a heat application step is performed before the stretching step, in which heat is applied to the rubber roll until the surface temperature of the rubber roll reaches or exceeds a predetermined reference temperature. Therefore, the unformed portion of the electrode sheet can be stretched using a rubber roll that has been treated so that the stretch rate of the unformed portion is stable. Therefore, variation in the degree of stretching of the unformed portion can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a flow diagram of manufacturing using an electrode sheet manufacturing apparatus 1. [Figure 2] FIG. 2 is a schematic diagram of the electrode sheet 10. [Figure 3] FIG. 3 is a schematic side view of the electrode sheet manufacturing apparatus 1. As shown in FIG. [Figure 4] FIG. 4 is a front view of the roll press machine 60. As shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along the line AA in FIG. [Figure 6] FIG. 6 is a block diagram of the electrode sheet manufacturing apparatus 1. [Figure 7] FIG. 7 is a flowchart showing the steps of the method for treating the electrode sheet 10. [Figure 8] FIG. 8 is a diagram showing a state in which the pressure roll 62 is pressed against the support roll 61. As shown in FIG. [Figure 9] FIG. 9 is a diagram showing the relationship between the surface temperature of the pressing roll 62 and the measurement time in the state shown in FIG. [Figure 10] FIG. 10 is a diagram showing a modified example of heat application to the pressure roll 62. In FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiment described here is, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, the same reference numerals are appropriately used for components and parts that perform the same function, and redundant explanations will be omitted where appropriate.

[0009] Fig. 1 is a flow diagram of production using an electrode sheet manufacturing apparatus 1. As shown in Fig. 1, production using the electrode sheet manufacturing apparatus 1 includes a conveying step S1, a measuring step S2, a kneading step S3, a coating step S4, a drying step S5, and a roll press step S6. However, production using the electrode sheet manufacturing apparatus 1 may also include other steps.

[0010] <Electrode sheet manufacturing equipment 1> An electrode sheet 10 (see FIG. 2) that constitutes an electricity storage device is manufactured in an electrode sheet manufacturing apparatus 1. The electrode sheet 10 constitutes the positive electrode sheet or negative electrode sheet of an electrode body housed inside the 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, and nickel-cadmium batteries, as well as capacitors (i.e., physical batteries) such as electric double layer capacitors. Below, as an example, the configuration of an electrode sheet 10 used in a lithium ion secondary battery will be described, along with the electrode sheet manufacturing apparatus 1 that manufactures the electrode sheet 10.

[0011] <Electrode sheet 10> FIG. 2 is a schematic diagram of an electrode sheet 10. As shown in FIG. 2, the electrode sheet 10 includes a current collector 12 and an electrode 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 electrode active material layer 14 is applied to a predetermined position on the current collector 12. The electrode active material layer 14 is formed on at least one surface of the strip-shaped current collector 12. In this embodiment, the electrode active material layer 14 is formed on both surfaces of the current collector 12. The electrode active material layer 14 is a layer containing an electrode active material. For example, a lithium transition metal composite oxide can be used as the positive electrode active material. Examples of the negative electrode active material that can be used include carbon materials, silicon-based materials, and mixed oxides thereof. The electrode active material layer may contain additives other than the electrode active material, such as a binder and a conductive material.

[0012] The electrode sheet 10 is formed by applying an electrode mixture slurry that will become the electrode active material layer 14 to a current collector 12 and drying the applied slurry. The current collector 12 has an uncoated portion 12a and a coated portion 12b. The uncoated portion 12a is a portion of the current collector 12 that is not coated with the electrode active material layer 14. The uncoated portion 12a is set along the length direction at the end portion in the width direction of the electrode sheet 10. In this embodiment, the uncoated portion 12a is set at both ends in the width direction of the electrode sheet 10. The uncoated portion 12a is an example of an unformed portion set as a portion where the electrode active material layer 14 is not formed. The coated portion 12b is located between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode mixture slurry is applied to the coated portion 12b. As a result, the electrode active material layer 14 is formed in the coated portion 12b of the current collector 12. That is, the electrode active material layer 14 is disposed between the uncoated portions 12a on both ends of the electrode sheet 10 in the width direction.

[0013] <Conveyor device 15> In the conveying step S1 shown in FIG. 1, the electrode sheet 10 is conveyed. FIG. 3 is a schematic side view of the electrode sheet manufacturing apparatus 1. The conveying step S1 can be achieved by a conveying device 15. The conveying device 15 conveys the electrode sheet 10. For example, a motor is used for the conveying device 15. The conveying device 15 includes an unwinding roll 15a and a take-up roll 15b so as to convey the electrode sheet 10 at a predetermined conveying speed. The unwinding roll 15a is disposed upstream of the roll press machine 60 in the conveying direction. The take-up roll 15b is disposed downstream of the roll press machine 60 in the conveying direction. However, the conveying device 15 is not limited to the unwinding roll 15a and the take-up roll 15b. For example, the conveying device 15 may include rolls in addition to the unwinding roll 15a and the take-up roll 15b. The electrode sheet 10 is conveyed by the conveying device 15 along a predetermined conveying path 18.

[0014] <Measuring process S2, kneading process S3, coating process S4, drying process S5> In the measuring step S2 shown in FIG. 1, raw materials for the electrode active material layer 14 (see FIG. 2) are measured. The measuring can be achieved, for example, by a measuring device (not shown) having a balance, a load cell, or the like. The measured raw materials for the electrode active material layer 14 are mixed in the kneading step S3. The kneading step S3 can be achieved by a kneading device (not shown). The raw materials for the electrode 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 the coating step S4. The coating step S4 can be achieved, for example, by a coating device (not shown) such as a slit coater, gravure coater, die coater, or comma coater. In the drying step S5, the applied raw materials for the electrode active material layer 14 in a slurry state are dried. The drying step S5 can be achieved, for example, by a drying device (not shown) that emits hot air or infrared rays.

[0015] <Roll press process S6> In the roll press step S6, the electrode sheet 10 is pressed. The roll press step S6 can be achieved by a roll press machine 60 shown in FIG. 3. As shown in FIG. 3, the electrode sheet 10 is pressed by the roll press machine 60 midway along the conveying path 18. The electrode sheet 10 is supplied by an unwinding roll 15a. The electrode sheet 10 pressed by the roll press machine 60 is taken up by a take-up roll 15b. The electrode sheet manufacturing apparatus 1 includes a control device 100 that controls the unwinding roll 15a, the take-up roll 15b, and the roll press machine 60.

[0016] FIG. 4 is a front view of a roll press machine 60. The roll press machine 60 according to this embodiment is a device that presses the uncoated portion 12a of the electrode sheet 10 with a rubber roll before or after pressing the coated portion 12b. When the uncoated portion 12a is pressed by the rubber roll, the uncoated portion 12a receives a reaction force due to elastic deformation and compressive deformation of the rubber roll, and the portion pressed by the roll is pressed and stretched. As a result, the uncoated portion 12a can be stretched while preventing breakage of the uncoated portion 12a. In view of this function, a device that presses the uncoated portion 12a of the electrode sheet 10 with a rubber roll may be appropriately referred to as an EPS (Elasticity Powered Stretching) device. The roll press machine 60 is an example of a stretching device, and is a device that conveys the electrode sheet 10 by pressing a pressure roll 62 (described below) against the uncoated portion 12a of the electrode sheet 10. In addition to the roll press machine 60, the electrode sheet manufacturing apparatus 1 may also include a device for pressing the coated portion 12b of the electrode sheet .

[0017] As shown in FIG. 4, the roll press machine 60 includes a support roll 61, a pressure roll 62, a temperature sensor 63, and a press pressure adjusting mechanism .

[0018] <Support Roll 61> The support roll 61 is disposed on the conveying path 18 (see FIG. 3). The support roll 61 supports the first surface 10D of the electrode sheet 10 conveyed along the conveying path 18 in the width direction of the electrode sheet 10. In this embodiment, the electrode sheet 10 has a first surface 10D and a second surface 10U. Here, the first surface 10D forms the lower surface of the electrode sheet 10. The second surface 10U is the surface of the electrode sheet 10 opposite to the first surface 10D. Here, the second surface 10U forms the upper surface of the electrode sheet 10. The support roll 61 is disposed below the pressing roll 62. The support roll 61 is a rubber roll that presses the uncoated portion 12a of the electrode sheet 10 together with the pressing roll 62. The support roll 61 is an example of another rubber roll defined in the present invention. In this embodiment, the support roll 61 has a main body portion 61a and two shaft portions 61b.

[0019] FIG. 5 is a cross-sectional view of the AA section in FIG. 4. FIG. 5 illustrates the state in which the uncoated portion 12a is pressed by the support roll 61 and the pressing roll 62. As shown in FIG. 5, the main body 61a includes a shaft portion 61aa and a rubber portion 61ab. The shaft portion 61aa is made of metal. The material for forming the shaft portion 61aa is not particularly limited, but is, for example, a material with relatively high hardness such as SUS304 (stainless steel). The rubber portion 61ab is arranged to cover at least the outer peripheral surface of the shaft portion 61aa. The material for forming the rubber portion 61ab is, for example, nitrile rubber (NBR). The support roll 61 presses the uncoated portion 12a of the electrode sheet 10 with the rubber portion 61ab.

[0020] The support roll 61 is rotated in a predetermined direction by a roll driving device 74 (see FIG. 4), which will be described later. In this embodiment, the support roll 61 rotates in the direction of arrow R1 shown in FIG. 5. At this time, the electrode sheet 10 is transported from left to right as viewed in the drawing. That is, the left side in FIG. 5 is the upstream side in the transport direction, and the right side in FIG. 5 is the downstream side in the transport direction.

[0021] As shown in Fig. 4, both shaft portions 61b are inserted into the main body portion 61a. Both shaft portions 61b are inserted into shaft portions 61aa (see Fig. 5) of the main body portion 61a. Both shaft portions 61b extend to the outside in the axial direction of the support roll 61. Although not shown, bearings, gap screws for adjusting the gap between the support roll 61 and the pressure roll 62, and the like are attached to both shaft portions 61b.

[0022] <Pressing Roll 62> As shown in FIG. 5, the pressing roll 62 is disposed opposite the support roll 61 on the second surface 10U (here, the upper surface) of the electrode sheet 10. The pressing roll 62 is disposed so as to sandwich the uncoated portion 12a of the electrode sheet 10 between itself and the support roll 61, excluding the coated portion 12b (see FIG. 2) of the electrode sheet 10. Here, the axial center of the pressing roll 62 and the axial center of the support roll 61 are aligned in the vertical direction. As shown in FIG. 4, the pressing roll 62, together with the support roll 61, presses the uncoated portion 12a of the electrode sheet 10. The pressing roll 62 is an example of a rubber roll. In this embodiment, a roll whose outer peripheral surface is at least made of rubber is referred to as a rubber roll. The pressing roll 62 is not disposed above the coated portion 12b (see FIG. 3) of the electrode sheet 10. In this embodiment, as described above, the uncoated portion 12a of the electrode sheet 10 is provided at both ends in the width direction of the electrode sheet 10. Therefore, as shown in FIG. 4, the pressing rolls 62 are respectively arranged above the uncoated portions 12a at both ends in the width direction of the electrode sheet 10. The number of pressing rolls 62 is two. However, the number of uncoated portions 12a may be one, and when there is one uncoated portion 12a, there may be one pressing roll 62. Of the two pressing rolls 62, the one arranged on the left will be referred to as pressing roll 62L, and the one arranged on the right will be referred to as pressing roll 62R. However, when describing either pressing roll 62L or 62R, the name pressing roll 62 will be used appropriately. The pressing rolls 62 (here, pressing rolls 62L and 62R) are replaceable and removable from the roll press machine 60. In this embodiment, the pressing roll 62 includes a main body portion 62a and two shaft portions 62b.

[0023] As shown in FIG. 5, the main body 62a includes a shaft portion 62aa and a rubber portion 62ab. The shaft portion 62aa is made of metal. The material for forming the shaft portion 62aa is not particularly limited, but is, for example, a material with relatively high hardness such as SUS304 (stainless steel). The rubber portion 62ab is arranged so as to cover at least the outer peripheral surface of the shaft portion 62aa. The material for forming the rubber portion 62ab is not particularly limited, but is, for example, nitrile rubber (NBR). The rubber portion 62ab is an example of rubber in the present invention. The pressing roll 62 presses the uncoated portion 12a of the electrode sheet 10 with the rubber portion 62ab.

[0024] As shown in Fig. 4, both shaft portions 62b are inserted into the main body portion 62a. Both shaft portions 62b are inserted into shaft portions 62aa (see Fig. 5) of the main body portion 62a. Both shaft portions 62b extend to the outside in the axial direction of the two pressing rolls 62. Although not shown, both shaft portions 62b may be fitted with bearings, gap screws for adjusting the gap between the support roll 61 and the pressing roll 62, or the like.

[0025] As shown in FIG. 5, when the support roll 61 and the pressing roll 62 sandwich the electrode sheet 10 and the support roll 61 rotates in the direction of arrow R1, the pressing roll 62 receives a force rotating in the direction of arrow R2 via the electrode sheet 10. Alternatively, when the electrode sheet 10 is not disposed and the support roll 61 and the pressing roll 62 are in contact, the pressing roll 62 receives a force rotating in the direction of arrow R2 due to the force of the rotation of the support roll 61 (see also FIG. 8). As a result, the pressing roll 62 rotates in the direction of arrow R2. In other words, the pressing roll 62 is a driven roll that rotates following the rotation of the support roll 61.

[0026] As shown in FIGS. 4 and 5, the temperature sensor 63 is arranged on the outer side in the circumferential direction of the pressing roll 62. In this embodiment, one temperature sensor 63 is arranged on the outer side in the circumferential direction of each of the pressing rolls 62L and 62R. The temperature sensor 63 is a sensor that measures the surface temperature of the rubber portion 62ab of the pressing roll 62 (hereinafter referred to as the "surface temperature of the pressing roll 62"). In this embodiment, the temperature sensor 63 is a sensor that measures the surface temperature of an object in a non-contact manner. The temperature sensor 63 measures the temperature of an object by detecting infrared rays emitted from the object. However, the type of the temperature sensor 63 is not limited to this. The temperature sensor 63 is connected to the control device 100 (see FIG. 3).

[0027] As shown in FIG. 4, the press pressure adjusting mechanism 70 includes a press cylinder 71, a roll chock 72, a cylinder driving device 73, a roll driving device 74, and a support portion 75.

[0028] The press cylinders 71 press the pressure roll 62 against the support roll 61. One press cylinder 71 is disposed on each end of the pressure roll 62, one on the outside. Here, in FIG. 4 , the press cylinder 71 disposed to the left of the electrode sheet 10 is referred to as press cylinder 71L, and the press cylinder 71 disposed to the right of the electrode sheet 10 is also referred to as press cylinder 71R. However, when describing matters common to the press cylinders 71L and 71R, they will also be referred to as press cylinder 71. In this embodiment, the press cylinder 71 is a pneumatic cylinder. The press cylinder 71 includes a rod 71a. The rod 71a is connected to a roll chock 72. The roll chock 72 is a member that rotatably supports both shaft portions 62b of the pressure roll 62. When the press cylinder 71 is driven and the rod 71a descends, the pressure roll 62 descends. When the press cylinder 71 is driven and the rod 71a rises, the pressure roll 62 rises.

[0029] The cylinder driving device 73 is a device that sandwiches the electrode sheet 10 and presses the pressing roll 62 against the support roll 61. The cylinder driving device 73 is connected to the press cylinder 71. The cylinder driving device 73 drives the press cylinder 71, thereby raising and lowering the rod 71a of the press cylinder 71. In this embodiment, the cylinder driving device 73 is configured to be able to independently drive the press cylinder 71L and the press cylinder 71R. In other words, the cylinder driving device 73 independently drives the pressing rolls 62 arranged above the uncoated portions 12a at both ends of the electrode sheet 10 in the width direction. The cylinder driving device 73 is connected to a control device 100 (see FIG. 3).

[0030] The roll driving device 74 is connected to the support roll 61. The roll driving device 74 is a device that rotates the support roll 61. In this embodiment, the roll driving device 74 rotates the support roll 61 in the direction of arrow R1 shown in FIG. 5. The configuration of the roll driving device 74 is not particularly limited, but may be configured by, for example, an electric motor, gears, etc. The roll driving device 74 is connected to a control device 100 (see FIG. 3). Note that the roll driving device 74 may also rotate the pressing roll 62.

[0031] The support portion 75 is a member that supports the support roll 61. The support portion 75 supports both shaft portions 61b of the support roll 61.

[0032] The control device 100 shown in FIG. 3 controls the roll press machine 60 as described above. The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but may include, for example, an I / F, a CPU, a ROM, a RAM, and a storage device. FIG. 6 is a block diagram of the electrode sheet manufacturing apparatus 1. As shown in FIG. 6, the control device 100 is communicatively connected to, for example, the conveying device 15, the temperature sensor 63, and the press pressure adjustment mechanism 70 (more specifically, the cylinder driving device 73 and the roll driving device 74). The control device 100 controls the conveying device 15 and the cylinder driving device 73 and the roll driving device 74 of the press pressure adjustment mechanism 70. In this embodiment, the control device 100 includes a heat application control unit 101, a receiving unit 102, a determination unit 103, and a stretching control unit 104. Each unit of the control device 100 may be realized by one or more processors or by a circuit.

[0033] The electrode sheet manufacturing apparatus 1 according to this embodiment has been described above. However, according to the knowledge of the present inventors, the elongation rate of the uncoated portion of the electrode sheet varies depending on the temperature of the pressure roll (rubber roll) that presses the current collector. That is, the higher the temperature of the pressure roll, the higher the elongation rate of the uncoated portion. Meanwhile, the pressure roll elastically deforms when stretching the uncoated portion. Therefore, when the pressure roll stretches the electrode sheet, the pressure roll generates heat, and the surface temperature of the pressure roll rises. When the uncoated portion is stretched, the surface temperature of the pressure roll rises, which tends to make the elongation rate of the current collector non-uniform.

[0034] Therefore, in this embodiment, the uncoated portion 12a of the electrode sheet 10 is stretched while suppressing the degree of variation in the stretching of the uncoated portion 12a. The inventors of the present application discovered that when the support roll 61 is rotated with the pressure roll 62 pressed against the support roll 61 without sandwiching the electrode sheet 10 between the pressure roll 62 and the support roll 61, the surface temperature of the pressure roll 62 saturates at a substantially constant temperature. The temperature at which the surface temperature of the pressure roll 62 saturates is defined as the reference temperature. The reference temperature is a temperature higher than the room temperature (approximately 25°C) of the room in which the roll press machine 60 is installed. In this embodiment, the reference temperature is 45°C. However, the value of the reference temperature is not limited to this. For example, the reference temperature varies depending on the ambient temperature of the pressure roll 62, the size of the pressure roll 62, etc.

[0035] The temperature of the pressure roll 62, which is an example of a rubber roll, is increased by applying heat to the pressure roll 62 until the surface temperature of the pressure roll 62 reaches or exceeds a predetermined reference temperature. In this embodiment, heat is applied to the pressure roll 62 by a roll press 60. Here, the roll press 60 is an example of a stretching device, but it is also an example of a heat application device that applies heat to a rubber roll. That is, the roll press 60 is a device that applies heat to the pressure roll 62, which presses the pressure roll 62 against the uncoated portion 12a of the electrode sheet 10 where the current collector foil is exposed, to stretch the uncoated portion 12a, until the surface temperature of the pressure roll 62 reaches or exceeds a predetermined reference temperature. Furthermore, the roll press 60 is a device that applies heat to the pressure roll 62 after heat is applied to the pressure roll 62, by pressing the pressure roll 62 against the uncoated portion 12a of the electrode sheet 10 to stretch the uncoated portion 12a. The roll press machine 60 according to this embodiment realizes that the stretching device and the heat applying device are the same device.

[0036] Next, a method for treating the electrode sheet 10 according to this embodiment will be described with reference to the flowchart of Fig. 7. Fig. 7 is a flowchart showing the steps of the method for treating the electrode sheet 10. As shown in Fig. 7, the method for treating the electrode sheet 10 includes a preparation step S101, a heat application step S102, a stretching step S103, and a main pressing step S104.

[0037] First, in the preparation step S101, an electrode sheet 10 to be processed is prepared. As shown in FIG. 2, the electrode sheet 10 prepared here is a strip-shaped sheet in which an electrode active material layer 14 is coated on a current collector 12 made of metal foil, and the current collector 12 has an uncoated portion 12a where the electrode active material layer 14 is not coated. Here, the electrode sheet 10 prepared in the preparation step S101 is the electrode sheet 10 produced through the measuring step S2, kneading step S3, coating step S4, and drying step S5 shown in FIG. 1. In other words, the electrode sheet 10 prepared in the preparation step S101 is an unstretched sheet. Note that in the preparation step S101, the electrode sheet 10 is not yet disposed between the support roll 61 and the pressing roll 62.

[0038] In the heat application step S102 shown in FIG. 7, heat is applied to the press roll 62 (see FIG. 4) until the surface temperature of the press roll 62 (see FIG. 4) reaches or exceeds a predetermined reference temperature. In this embodiment, heat is applied to the press roll 62 by rotating the press roll 62 while it is pressed against the support roll 61 (see FIG. 4). In the heat application step S102, first, the heat application control unit 101 shown in FIG. 6 controls the cylinder drive device 73 and the roll drive device 74. The cylinder drive device 73 lowers the rod 71a (see FIG. 4) of the press cylinder 71. The cylinder drive device 73 lowers the rod 71a to a predetermined position. As a result, the press roll 62 (see FIG. 4) lowers and is pressed against the support roll 61 (see FIG. 4). FIG. 8 is a diagram showing a state in which the press roll 62 is pressed against the support roll 61. As shown in FIG. 8, the press roll 62 is pressed against the support roll 61. At this time, the roll driver 74 (see FIG. 6) rotates the support roll 61. In the heat application step S102, the pressing roll 62 is rotated at a first rotation speed. The heat application control unit 101 (see FIG. 7) causes the roll driver 74 to rotate the support roll 61 so that the rotation speed of the pressing roll 62 becomes the first rotation speed. The value of the first rotation speed is not particularly limited. In this embodiment, as shown in FIG. 8, the roll driver 74 rotates the support roll 61 in the direction of arrow R1. As a result, the pressing roll 62 is rotated while being pressed against the support roll 61.

[0039] When the pressure roll 62 rotates while being pressed against the support roll 61, as shown in FIG. 8, the rubber portion 61ab of the support roll 61 and the rubber portion 62ab of the pressure roll 62 are compressed and deformed. The rubber portions 61ab and 62ab are subjected to a force in a direction compressing them at and near their contact points, causing them to compress and deform. When the support roll 61 and the pressure roll 62 continue to rotate from the state shown in FIG. 8, the compressed portions of the rubber portions 61ab and 62ab elastically return to their original shapes. Therefore, when the support roll 61 and the pressure roll 62 rotate, the rubber portions 61ab and 62ab elastically deform in the radial direction of the support roll 61 and the pressure roll 62 at and near their contact points. This elastic deformation is repeated along the circumferential direction of the support roll 61 and the pressure roll 62. As the rubber portions 61ab and 62ab repeatedly undergo elastic deformation, they generate heat. Therefore, the surface temperature of the pressing roll 62 gradually increases. In the heat application step S102, as shown in FIG. 8, the temperature sensor 63 measures the surface temperature of the rubber portion 62ab of the pressing roll 62. FIG. 9 is a diagram showing the relationship between the surface temperature of the pressing roll 62 and the measurement time in the state of FIG. 8. As shown in FIG. 9, in region A1, the change in surface temperature with respect to the change in measurement time is relatively large. Region A1 is the region of the graph when the surface temperature of the pressing roll 62 is lower than the reference temperature. On the other hand, in region A2, the change in surface temperature with respect to the change in measurement time is relatively small. Region A2 is the region of the graph when the surface temperature of the pressing roll 62 is equal to or higher than the reference temperature.

[0040] The receiving unit 102 shown in FIG. 6 receives the temperature measured by the temperature sensor 63. The receiving unit 102 may receive the temperature measured by the temperature sensor 63 continuously or at predetermined time intervals. The determining unit 103 determines whether the temperature value received by the receiving unit 102 is equal to or higher than a reference temperature. If the temperature value received by the receiving unit 102 is lower than the reference temperature, the application of heat to the pressing roll 62 continues. If the temperature received by the receiving unit 102 is equal to or higher than the reference temperature, the heat application control unit 101 stops the rotation of the pressing roll 62. That is, the roll driving device 74 stops the rotation of the support roll 61. Furthermore, the cylinder driving device 73 raises the rod 71a to separate the pressing roll 62 and the support roll 61.

[0041] Next, in a stretching step S103 shown in FIG. 7, the uncoated portion 12a of the electrode sheet 10 is stretched by the stretching control unit 104 (see FIG. 6). Here, while the electrode sheet 10 is being transported, a pressure roll 62 is pressed against the uncoated portion 12a of the electrode sheet 10, thereby stretching the uncoated portion 12a. In the stretching step S103, first, the stretching control unit 104 drives the transport device 15. As a result, the electrode sheet 10 is transported and positioned between the pressure roll 62 and the support roll 61. Next, the stretching control unit 104 controls the cylinder drive device 73 and the roll drive device 74. The cylinder drive device 73 lowers the rod 71a (see FIG. 4) of the press cylinder 71. The cylinder drive device 73 lowers the rod 71a to a predetermined position. As a result, as shown in FIG. 5, the uncoated portion 12a of the electrode sheet 10 is sandwiched between the pressure roll 62 and the support roll 61. At this time, the roll driver 74 rotates the support roll 61. In this embodiment, as shown in FIG. 5, the support roll 61 is rotated in the direction of arrow R1. At this time, the pressure roll 62 rotates in the direction of R2. In the stretching step S103, the pressure roll 62 is rotated at a second rotation speed that is faster than the first rotation speed to stretch the uncoated portion 12a of the electrode sheet 10. That is, under the control of the stretching control unit 104, the roll driver 74 rotates the support roll 61 so that the rotation speed of the pressure roll becomes the second rotation speed. The value of the second rotation speed is not particularly limited as long as it is faster than the first rotation speed.

[0042] As shown in FIG. 5, the rubber portion 61ab of the support roll 61 and the rubber portion 62ab of the pressure roll 62 are compressed and deformed near the uncoated portion 12a. When the support roll 61 and the pressure roll 62 continue to rotate from the state shown in FIG. 5, the compressed portion of the rubber portion 61ab returns to its original shape due to elasticity. At this time, the portions of the rubber portions 61ab and 62ab that have moved near the uncoated portion 12a are compressed. Therefore, when the support roll 61 and the pressure roll 62 rotate and the electrode sheet 10 is transported, the rubber portions 61ab and 62ab in the vicinity of the uncoated portion 12a repeatedly undergo elastic deformation along the circumferential direction of the support roll 61 and the pressure roll 62. In this manner, the uncoated portion 12a is compressed and stretched.

[0043] Next, in the main pressing step S104 shown in FIG. 7, after the stretching step S103, the electrode active material layer 14 (here, the coated portion 12b) of the electrode sheet 10 is pressed. In the main pressing step S104, as described above, the coated portion 12b is pressed using, for example, a dedicated device for pressing the coated portion 12b. This allows the coated portion 12b to be stretched. The electrode sheet 10 can be manufactured by the above procedure.

[0044] As described above, the method for treating the electrode sheet 10 in this embodiment includes a preparation step S101, a heat application step S102, and a stretching step S103. In the preparation step S101, a strip-shaped electrode sheet 10 having an uncoated portion 12a is prepared. In the heat application step S102, the heat application control unit 101 applies heat to the pressing roll 62 until the surface temperature of the pressing roll 62 reaches or exceeds a reference temperature. When the surface temperature of the pressing roll 62 is equal to or higher than the reference temperature, the change in surface temperature is relatively small even when the rubber portion 62ab of the pressing roll 62 elastically deforms. The heat application step S102 is performed before the stretching step S103 is performed. In the stretching step S103, the stretching control unit 104 stretches the uncoated portion 12a using the pressing roll 62. When the uncoated portion 12a is stretched, the rubber portion 62ab of the pressing roll 62 elastically deforms. However, the surface temperature of the pressing roll 62 has already reached the reference temperature or higher in the heat application step S102. Therefore, even if the rubber portion 62ab is elastically deformed in the stretching step S103, the surface temperature of the pressing roll 62 is relatively unlikely to change. Therefore, it is possible to suppress variations in the stretching of the uncoated portion 12a.

[0045] According to the method for treating the electrode sheet 10 in this embodiment, in the heat application step S102, the pressure roll 62 is rotated while being pressed against the support roll 61, thereby applying heat to the pressure roll 62. When the pressure roll 62 is rotated while being pressed against the support roll 61, the rubber portion 62ab of the pressure roll 62 repeatedly elastically deforms in the circumferential direction. Therefore, the surface temperature of the entire pressure roll 62 can be increased relatively uniformly.

[0046] According to the method for treating the electrode sheet 10 in this embodiment, in the heat application step S102, the pressing roll 62 is rotated at a first rotation speed. In the stretching step S103, the pressing roll 62 is rotated at a second rotation speed. The second rotation speed is faster than the first rotation speed. In the heat application step S102, the pressing roll 62 is rotated slower than during stretching, which makes it easier for heat to be applied to the pressing roll 62. Therefore, the time required for the surface temperature of the pressing roll 62 to reach a temperature equal to or higher than the reference temperature can be made relatively short.

[0047] According to the electrode sheet manufacturing apparatus 1 of this embodiment, the roll press machine 60 is an example of a stretching device, but is also an example of a heat applying device that applies heat to a rubber roll. Therefore, the roll press machine 60 realizes both a stretching device and a heat applying device. This makes it possible to use a single roll press machine 60 to apply heat to the pressure roll 62 and to stretch the uncoated portion 12a of the electrode sheet 10.

[0048] According to the electrode sheet manufacturing apparatus 1 of this embodiment, the reference temperature is higher than the room temperature of the room in which the roll press machine 60 (stretching device) is installed. If the reference temperature is lower than room temperature, even if the surface temperature of the pressing roll 62 is raised to the reference temperature, the surface temperature of the pressing roll 62 will then further rise due to room temperature. This may result in variations in the stretch rate of the electrode sheet 10. Therefore, by setting the reference temperature higher than room temperature as in this embodiment, changes in the surface temperature of the pressing roll 62 due to the air in the room in which the roll press machine 60 is installed are suppressed.

[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] In the above-described embodiment, the surface temperature of the pressure roll 62 is increased by rotating the pressure roll 62 while it is pressed against the support roll 61. However, the method of applying heat to the pressure roll 62 is not limited to this. FIG. 10 is a diagram showing a modified example of applying heat to the pressure roll 62. Like FIG. 5, FIG. 10 illustrates cross sections of the pressure roll 62 and the support roll 61. The roll press 60A shown in FIG. 10 is equipped with a high-heat roll 64. The roll press 60A is equipped with two high-heat rolls 64. One of the two high-heat rolls 64 is disposed above the pressure roll 62, and the other of the two high-heat rolls 64 is disposed below the support roll 61. The high-heat roll 64 is connected to a drive device (not shown). The drive device allows the high-heat roll 64 to move up and down. The drive device also allows the high-heat roll 64 to rotate.

[0051] The high-heat roll 64 is, for example, a metal roll. The surface of the high-heat roll 64 has a temperature equal to or higher than a reference temperature. The method for raising the surface temperature of the high-heat roll 64 is not particularly limited. For example, the high-heat roll 64 has an internal heater that heats its surface. The high-heat roll 64 is moved by driving a driving device. As shown in FIG. 10 , the high-heat roll 64 is moved so that the pressure roll 62 and the support roll 61 are pressed against the high-heat roll 64. When the high-heat roll 64 is rotated by the driving device in this state, the surface temperatures of the pressure roll 62 and the support roll 61 rise due to heat generated by elastic deformation of the rubber portions 61ab and 62ab and heat transfer from the high-heat roll 64. Therefore, heat can be applied to the pressure roll 62 until the surface temperature reaches or exceeds the reference temperature. The high-heat roll 64 may be one that applies heat only to the pressure roll 62 , that is, the number of high-heat rolls 64 may be one that is pressed against the pressure roll 62 only.

[0052] As described above, this specification includes the disclosures set forth in the following sections.

[0053] Section 1: a preparation step of preparing a strip-shaped electrode sheet in which an electrode active material layer is coated on a current collector made of a metal foil, the current collector having an unformed portion where the electrode active material layer is not formed; a stretching step of stretching the unformed portion of the electrode sheet by pressing a rubber roll against the unformed portion of the electrode sheet while transporting the strip-shaped electrode sheet; a heat application step of applying heat to the rubber roll until a surface temperature of the rubber roll reaches or exceeds a predetermined reference temperature before the stretching step; A method for treating an electrode sheet, comprising:

[0054] Section 2: Item 2. The electrode sheet treating method according to item 1, wherein in the heat application step, heat is applied to the rubber roll by rotating the rubber roll while being pressed against another rubber roll.

[0055] Section 3: In the heat application step, the rubber roll is rotated at a first rotation speed, Item 3. The electrode sheet treating method according to Item 2, wherein in the stretching step, the rubber roll is rotated at a second rotation speed that is faster than the first rotation speed to stretch the unformed portion of the electrode sheet.

[0056] Section 4: a heat applying device that applies heat to a rubber roll that is pressed against an unformed portion of the electrode sheet where the current collecting foil is exposed, thereby stretching the unformed portion, until a surface temperature of the rubber roll reaches a predetermined reference temperature or higher; a stretching device that presses the rubber roll against the unformed portion of the electrode sheet after heat is applied to the rubber roll by the heat application device, and stretches the unformed portion; An electrode sheet manufacturing device comprising:

[0057] Section 5: Item 5. The electrode sheet manufacturing apparatus according to item 4, wherein the heat applying device and the stretching device are the same device.

[0058] Item 6: Item 6. The electrode sheet manufacturing apparatus according to item 4 or 5, wherein the reference temperature is higher than the room temperature of a room in which the stretching device is installed. [Explanation of symbols]

[0059] 1. Electrode sheet manufacturing equipment 10 Electrode sheet 12 Current collector 12a Uncoated area (unformed area) 12b Coating Department 14 Electrode active material layer 15. Conveying equipment 15a Unwinding roll 15b Winding roll 18 Transport Route 60 Roll press machine (stretching device, heat applying device) 60A Roll Press Machine 61 Support Roll 61a Main body 61aa Shaft 61ab,62ab rubber part 61b, 62b Both shafts 62, 62L, 62R pressure roll 62a Main body 62aa shaft 62ab rubber part 62b Both shafts 63 Temperature Sensor 64 High Heat Roll 70 Press pressure adjustment mechanism 71 Press Cylinder 71, 71L, 71R Press Cylinder 71a Rod 72 Roll Chock 73 Cylinder drive unit 74 Roll drive unit 75 Support part 100 control device 101 Heat application control section 102 Receiving unit 103 Judgment section 104 Extension control section A1 area A2 Field R1 Yayin R2 Yayin S101 Intentional Engineering S102 Heat Transfer and Engineering S103 Extension Project S104 This project S105 This project S1 moving project S2 Measurement Engineering S3 Mixed Processing Project S4 Coating Project S5 Drying Process S6 ロールプレス Engineering

Claims

1. a preparation step of preparing a strip-shaped electrode sheet in which an electrode active material layer is coated on a current collector made of a metal foil, the current collector having an unformed portion where the electrode active material layer is not formed; a stretching step of stretching the unformed portion of the electrode sheet by pressing a rubber roll against the unformed portion of the electrode sheet while transporting the strip-shaped electrode sheet; a heat application step of applying heat to the rubber roll until a surface temperature of the rubber roll reaches or exceeds a predetermined reference temperature before the stretching step; A method for treating an electrode sheet, comprising:

2. 2. The electrode sheet treating method according to claim 1, wherein in the heat applying step, heat is applied to the rubber roll by rotating the rubber roll while being pressed against another rubber roll.

3. In the heat application step, the rubber roll is rotated at a first rotation speed, The electrode sheet treating method according to claim 2 , wherein in the stretching step, the rubber roll is rotated at a second rotation speed that is faster than the first rotation speed to stretch the unformed portion of the electrode sheet.

4. a heat applying device that applies heat to a rubber roll that is pressed against an unformed portion of the electrode sheet where the current collecting foil is exposed, thereby stretching the unformed portion, until a surface temperature of the rubber roll reaches a predetermined reference temperature or higher; a stretching device that presses the rubber roll against the unformed portion of the electrode sheet after heat is applied to the rubber roll by the heat application device, and stretches the unformed portion; An electrode sheet manufacturing device comprising:

5. 5. The electrode sheet manufacturing apparatus according to claim 4, wherein the heat applying device and the stretching device are the same device.

6. The electrode sheet manufacturing apparatus according to claim 4 , wherein the reference temperature is higher than a room temperature in a room where the stretching device is installed.

Images