Method for processing electrode sheet and electrode manufacturing system

Abstract

To make it possible to stabilize an elongation rate of a non-formed part of an electrode sheet.SOLUTION: A method for processing an electrode sheet 10 includes a preparation step S101 and an elongation step S104. In the preparation step S101, a belt-shaped electrode sheet 10 having an electrode active material layer 14 formed on a collector 12 made of metal foil, the collector 12 of the electrode sheet 10 having a non-formed part 12a on which no electrode active material layer 14 is formed is prepared. In the elongation step S104, the non-formed part 12a of the electrode sheet 10 is elongated by pressing a rubber roll 62 onto the non-formed part 12a while transferring the electrode sheet 10. In the elongation step S104, the rubber roll 62 is used such that a change amount of an elongation rate of the non-formed part 12a elongated by the rubber roll 62 becomes equal to or smaller than a predetermined normal change amount NC1 in a predetermined normal time NT1.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a method for processing an electrode sheet and an electrode manufacturing system. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open No. 2023-36089 discloses a method for manufacturing an electrode in a precursor sheet (in other words, an electrode sheet) having a metal foil, a coated portion on the metal foil where an electrode material is coated, and an uncoated portion on the metal foil where the electrode material is not coated, in which the uncoated portion is pressed with a pair of elastic rolls (in other words, rubber rolls).

[0003] For example, when an uncoated portion is pressed with a roll other than an elastic roll, tensile force or the like can cause voids to form inside the uncoated portion. These voids can cause the uncoated portion to break. 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 compressive force is a force that occurs when the pair of elastic rolls come into contact with each other and deform the elastic rolls. This allows the uncoated portion to be stretched while preventing breakage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-36089 Summary of the Invention [Problem to be solved by the invention]

[0005] In the electrode manufacturing method disclosed in JP 2023-36089 A, when the elastic roll is replaced with a new elastic roll and the uncoated portion of the precursor sheet is stretched using the new elastic roll, the stretch rate of the uncoated portion may vary. It is preferable that the stretch rate of the uncoated portion is stable around a predetermined value. [Means for solving the problem]

[0006] The electrode sheet processing method disclosed herein includes a preparation step of preparing a strip-shaped electrode sheet having an electrode active material layer formed on a current collector made of metal foil, the electrode sheet having an unformed portion on the current collector where the electrode active material layer is not formed, and 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 electrode sheet. In the stretching step, a rubber roll is used such that the amount of change in the stretch rate of the unformed portion stretched by the rubber roll within a predetermined reference time is equal to or less than a predetermined reference change amount.

[0007] According to the electrode sheet processing method disclosed herein, the unformed portion of the electrode sheet can be stretched using a rubber roll that has been treated so as to stabilize the stretch rate of the unformed portion, thereby suppressing variation in the degree of stretching of the unformed portion.

[0008] The electrode manufacturing system disclosed herein includes a rubber roll that presses against an unformed portion of an electrode sheet where a current collector made of metal foil is exposed, thereby stretching the unformed portion, and a pre-loading device that applies a load to the rubber roll until a change in the elongation rate of the unformed portion stretched by the rubber roll over a predetermined reference time period becomes equal to or less than a predetermined reference change, and a stretching device that presses the rubber roll against the unformed portion of the electrode sheet and transports the electrode sheet after the pre-loading device has applied a load to the rubber roll. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow diagram of manufacturing by the electrode manufacturing system. [Figure 2] FIG. 2 is a schematic diagram of an electrode sheet. [Figure 3] FIG. 3 is a schematic side view of an electrode manufacturing system. [Figure 4]FIG. 4 is a front view of the roll press machine. [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 an electrode manufacturing system. [Figure 7] FIG. 7 is a flowchart showing the steps of the electrode sheet processing method. [Figure 8] FIG. 8 is a graph showing the relationship between the time required to remove creep from the target pressure roll and the elongation rate of the uncoated portion of the electrode sheet. [Figure 9] FIG. 9 is a view equivalent to FIG. 5, showing a state in which a load is applied to the target pressing roll in the roll press machine. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of the technology disclosed herein will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Each drawing is a schematic diagram and does not necessarily faithfully reflect an 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.

[0011] Fig. 1 is a flow diagram of production by the electrode production system 1. As shown in Fig. 1, production by the electrode production system 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 by the electrode production system 1 may also include other steps.

[0012] In the electrode manufacturing system 1, an electrode sheet 10 (see FIG. 2) that constitutes an electricity storage device is manufactured. The electrode sheet 10 has a positive electrode sheet or a negative electrode sheet of an electrode body that is housed inside the electricity storage device. The 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. Below, as an example, the configuration of the electrode sheet 10 used in a lithium ion secondary battery will be described, along with the electrode manufacturing system 1 that manufactures the electrode sheet 10.

[0013] FIG. 2 is a schematic diagram of an electrode sheet 10. As shown in FIG. 2, the electrode sheet 10 is in the form of a long strip. 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. As an example of the current collector 12, a positive electrode current collector foil can be used, for example, aluminum or an aluminum alloy. As another example of the current collector 12, a negative electrode current collector foil can be used, for example, copper or a copper alloy. The electrode active material layer 14 is coated at 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. As an example of the electrode active material, a lithium transition metal composite oxide can be used as the positive electrode active material. As another example of the electrode active material, a negative electrode active material can be used as the negative electrode active material. For example, a carbon material, a silicon-based material, or a mixed oxide thereof can be used. The electrode active material layer may contain additives other than the electrode active material, such as a binder or a conductive material.

[0014] 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 an example of an unformed portion. The uncoated portion 12a is a portion of the current collector 12 where the electrode active material layer 14 is not formed. In other words, 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 of the current collector 12 at a predetermined position in the width direction. The uncoated portion 12a is set along the length of the electrode sheet 10 at an end in the width direction. In this embodiment, the uncoated portion 12a is set at both ends of the electrode sheet 10 in the width direction. The coated portion 12b is arranged between the uncoated portions 12a at both ends of the electrode sheet 10. The coated portion 12b is a portion of the current collector 12 on which the electrode active material layer 14 is formed (in other words, coated). The electrode composite slurry is applied to the coated portion 12b. As a result, the electrode active material layer 14 is formed on the coated portion 12b of the current collector 12. That is, the electrode active material layer 14 is disposed between the uncoated portions 12a at both ends of the electrode sheet 10 in the width direction. The electrode active material layer 14 is formed on the current collector 12 in a region other than the uncoated portion 12a. Although not shown, a protective layer containing an inorganic filler may be provided at the boundary between the uncoated portion 12a and the coated portion 12b. When a protective layer is formed, when an EPS rubber roll is pressed against the electrode sheet, the elongation percentage may not be the same between the region where the protective layer is formed and the region where the protective layer is not formed.

[0015] In the transport step S1 shown in FIG. 1, an electrode sheet 10 is transported. FIG. 3 is a schematic side view of an electrode manufacturing system 1. In this embodiment, the electrode manufacturing system 1 includes a transport device 15. The transport step S1 can be achieved by the transport device 15. The transport device 15 transports the electrode sheet 10. For example, a motor is used for the transport device 15. The transport device 15 includes an unwinding roll 15a and a take-up roll 15b so as to transport the electrode sheet 10 at a predetermined transport speed. The electrode sheet 10 is wound around the unwinding roll 15a and the take-up roll 15b. The unwinding roll 15a is arranged upstream of a roll press machine 60 (described later) in the transport direction. The take-up roll 15b is arranged downstream of the roll press machine 60 in the transport direction. However, the transport device 15 is not limited to a configuration including the unwinding roll 15a and the take-up roll 15b. For example, the transport device 15 may be provided with rolls in addition to the unwinding roll 15a and the winding roll 15b. The transport device 15 transports the electrode sheet 10 along a predetermined transport path 18.

[0016] 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 by a measuring device (not shown) having, for example, 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 electrode active material layer 14, which has been made into a slurry by the kneading device, is formed on the current collector 12 (see FIG. 2) in the coating step S4. Here, the electrode active material layer 14 is formed by coating the current collector 12. However, the electrode active material layer 14 may also be formed on the current collector 12 by a method other than coating. 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 the drying step S5 shown in FIG. 1, the coated raw materials for the electrode active material layer 14 in a slurry state are dried. The drying step S5 is realized by a drying device (not shown) that emits, for example, hot air or infrared rays.

[0017] In the roll press step S6 shown in FIG. 1, the electrode sheet 10 is pressed. The electrode sheet 10 is stretched by being pressed. The roll press step S6 can be achieved by a roll press machine 60 shown in FIG. 3. The electrode manufacturing system 1 is equipped with the roll press machine 60. 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 to the roll press machine 60 by an unwinding roll 15a. The electrode sheet 10 pressed by the roll press machine 60 is conveyed toward the take-up roll 15b and taken up by the take-up roll 15b. The electrode manufacturing system 1 is equipped with a control device 100 that controls the unwinding roll 15a, the take-up roll 15b, and the roll press machine 60.

[0018] 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 of the electrode sheet 10. When the uncoated portion 12a is pressed by the rubber roll, the portion pressed by the rubber roll is pressed and stretched due to the reaction force of the elastic deformation and compressive deformation of the rubber roll. As a result, the uncoated portion 12a can be stretched while preventing breakage of the uncoated portion 12a. Due to 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 manufacturing system 1 may also include a device for pressing the coated portion 12b of the electrode sheet .

[0019] As shown in FIG. 4, the roll press machine 60 includes a support roll 61, a pressing roll 62, and a pressing pressure adjusting mechanism .

[0020] 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 and an example of an object to be pressed. In this embodiment, the support roll 61 has a main body portion 61a and two shaft portions 61b.

[0021] FIG. 5 is a cross-sectional view of the AA section in FIG. 4. FIG. 5 shows a 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 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 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.

[0022] 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 FIG. 5. That is, in FIG. 5, the left side is the upstream side in the transport direction, and the right side is the downstream side in the transport direction.

[0023] 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, both shaft portions 61b may be fitted with bearings or gap screws for adjusting the gap between the support roll 61 and the pressure roll 62.

[0024] 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 of the electrode sheet 10. In this embodiment, as described above, the uncoated portions 12a of the electrode sheet 10 are two, that is, located 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.

[0025] As shown in FIG. 5, the main body 62a includes a shaft 62aa and a rubber portion 62ab. The shaft 62aa is made of metal. The material for the shaft 62aa is not particularly limited, but may be, for example, a material with a relatively high hardness such as SUS304 (stainless steel). The rubber portion 62ab is disposed so as to cover at least the outer peripheral surface of the shaft 62aa. The material for the rubber portion 62ab is not particularly limited, but may be, for example, nitrile rubber (NBR). The pressing roll 62 presses the uncoated portion 12a of the electrode sheet 10 with the rubber portion 62ab.

[0026] 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 or gap screws for adjusting the gap between the support roll 61 and the pressing roll 62.

[0027] As shown in Fig. 5, when the support roll 61 and the pressure roll 62 sandwich the electrode sheet 10 and the support roll 61 rotates in the direction of arrow R1, the pressure 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 pressure roll 62 are in contact, the pressure roll 62 receives a force rotating in the direction of arrow R2 due to the force of the rotation of the support roll 61. As a result, the pressure roll 62 rotates in the direction of arrow R2. In other words, the pressure roll 62 is a driven roll that rotates in conjunction with the rotation of the support roll 61.

[0028] 4, the press pressure adjustment mechanism 70 is a mechanism that adjusts the force (i.e., the press pressure) with which the press roll 62 presses the electrode sheet 10. The press pressure adjustment mechanism 70 includes a press cylinder 71, a roll chock 72, a cylinder drive device 73, a roll drive device 74, and a support part 75.

[0029] The press cylinders 71 press the pressure roll 62 against the support roll 61. One press cylinder 71 is arranged on each end of the pressure roll 62, one on the outside. Here, in FIG. 4, the press cylinder 71 arranged to the left of the electrode sheet 10 will be referred to as the press cylinder 71L, and the press cylinder 71 arranged to the right of the electrode sheet 10 will also be referred to as the press cylinder 71R. However, when describing matters common to the press cylinders 71L and 71R, they will also be referred to as the 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. As the pressing roll 62 descends, the pressing roll 62 is pressed against the support roll 61, increasing the pressing pressure. When the press cylinder 71 is driven and the rod 71a rises, the pressing roll 62 rises. As the pressing roll 62 rises, the pressing pressure decreases.

[0030] The cylinder driving device 73 is a device that 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).

[0031] 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.

[0032] 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.

[0033] 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 manufacturing system 1. As shown in FIG. 6, the control device 100 is communicatively connected to, for example, the conveying device 15 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 memory unit 101, a pre-load control unit 103, and a stretching control unit 105. The memory unit 101, the pre-load control unit 103, and the stretching control unit 105 may be realized by one or more processors or by circuits.

[0034] The electrode manufacturing system 1 according to the present embodiment has been described above. Incidentally, as shown in FIG. 4 , in the electrode manufacturing system 1, the press rolls 62 (here, press rolls 62L and 62R), which are an example of a rubber roll, are removable and replaceable. The press roll 62, particularly its rubber portion (here, rubber portion 62ab), is a consumable item, and is replaced with a new press roll 62 after being used for a predetermined time or number of times. In the following description, the new press roll 62 is also referred to as the target press roll 62T (see FIG. 5 ). As shown in FIG. 5 , when the target press roll 62T is pressed against the uncoated portion 12a of the electrode sheet 10 to stretch the uncoated portion 12a, the stretch rate of the uncoated portion 12a can vary. For example, when a new target press roll 62T is used to stretch the uncoated portion 12a, the stretch rate of the uncoated portion 12a is initially low and gradually increases over time. Then, after a predetermined time had elapsed using the target pressing roll 62T, the stretching rate of the uncoated portion 12a became stable.

[0035] Therefore, in this embodiment, even when a new target pressing roll 62T is used, the stretching rate of the uncoated portion 12a of the electrode sheet 10 is stabilized and the uncoated portion 12a is stretched. The present inventors investigated the reason why the stretching rate of the uncoated portion 12a is initially low when a new target pressing roll 62T is used. As a result of various investigations, they found that when the target pressing roll 62T, which is a rubber roll, is new, so-called creep occurs in the target pressing roll 62T, causing the stretching rate of the uncoated portion 12a to become low and unstable. In other words, they found that eliminating creep in the target pressing roll 62T makes it easier to stabilize the stretching rate of the uncoated portion 12a.

[0036] For example, when a load is applied to rubber, a certain amount of elastic deformation occurs in the rubber. If a certain amount of load is continued to be applied to the rubber while a certain amount of elastic deformation has occurred, the deformation of the rubber gradually increases over time. This phenomenon is called creep. In this embodiment, the target pressure roll 62T is in a state where a certain amount of load is applied when pressed against the electrode sheet 10. Therefore, when a new target pressure roll 62T continues to be pressed against the electrode sheet 10, a certain amount of load is continuously applied, and the deformation of the rubber increases over time, resulting in creep. Note that rubber creep is likely to occur in new rubber. Furthermore, rubber creep is eliminated when the load state continues, for example, until a predetermined elapsed time has elapsed, and the elastic deformation of the rubber stabilizes. In this embodiment, the process of continuing to apply a load to a new target pressure roll 62T and stabilizing the elastic deformation of the rubber of the pressure roll 62 is called "creep removal."

[0037] In this embodiment, when the pressing roll 62 attached to the roll press machine 60 is replaced with a new target pressing roll 62T, a load is applied to the new target pressing roll 62T to remove creep. Then, the target pressing roll 62T for which creep removal has been performed is used to press the uncoated portion 12a of the electrode sheet 10, thereby stabilizing the elongation rate of the uncoated portion 12a and achieving the elongation of the uncoated portion 12a.

[0038] Creep removal of the target pressing roll 62T, which is an example of a rubber roll, is performed by applying a load to the target pressing roll 62T for a predetermined load time T1 (see FIG. 8). In this embodiment, the load on the target pressing roll 62T is performed by a roll press machine 60. Here, the roll press machine 60 is an example of a stretching device as described above, but is also an example of a pre-loading device that applies a load to the rubber roll. The roll press machine 60 according to this embodiment realizes that the stretching device and the pre-loading device are the same device.

[0039] Next, a method for treating an electrode sheet 10 according to this embodiment will be described with reference to the flowchart of Fig. 7. Here, in the method for treating an electrode sheet 10, creep removal is performed on a new target pressing roll 62T, and the uncoated portion 12a of the electrode sheet 10 is stretched using the creep-removed target pressing roll 62T to process the electrode sheet 10. As shown in Fig. 7, the method for treating an electrode sheet 10 includes a preparation step S101, a replacement step S102, a pre-loading step S103, a stretching step S104, and a main pressing step S105.

[0040] 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 weighing step S2, kneading step S3, coating step S4, and drying step S5 shown in FIG. 1. That is, the electrode sheet 10 prepared in the preparation step S101 is an unstretched sheet. In this embodiment, a new target pressing roll 62T (see FIG. 5) to be replaced is also prepared in the preparation step S101. The new target pressing roll 62T here refers to the pressing roll 62 that has not yet been pressed against the uncoated portion 12a of the electrode sheet 10 to stretch the uncoated portion 12a. The new target pressing roll 62T prepared here is an example of a replacement rubber roll.

[0041] Next, in a replacement step S102 in Fig. 7, the pressing roll 62 already attached to the roll press machine 60 is replaced with a new target pressing roll 62T. The new target pressing roll 62T at this time is the target pressing roll 62T prepared in the preparation step S101. Here, an operator removes the already attached pressing roll 62 from the roll press machine 60, and then attaches the new target pressing roll 62T to the roll press machine 60. In this embodiment, the target pressing roll 62T replaced in the replacement step S102 is in a state where creep has not yet been removed.

[0042] Next, in the pre-loading step S103 of FIG. 7 , a load is applied to a new target pressing roll 62T to remove creep. Here, creep removal is performed by a roll press machine 60, which is an example of a pre-loading device. FIG. 8 is a graph showing the relationship between the time required for creep removal of the target pressing roll 62T and the elongation rate of the uncoated portion 12a of the electrode sheet 10. As shown in FIG. 8 , creep removal here refers to applying a load to the new target pressing roll 62T so that the amount of change in the elongation rate of the uncoated portion 12a stretched by the new target pressing roll 62T during a predetermined reference time NT1 is equal to or less than a predetermined reference change amount NC1. That is, when the amount of change in the elongation rate of the uncoated portion 12a stretched by the new target pressing roll 62T during the reference time NT1 is equal to or less than the reference change amount NC1, the elongation rate is stable, and it is determined that creep removal has been performed.

[0043] FIG. 9 is a view equivalent to FIG. 5 showing a state in which a load is being applied to the target pressing roll 62T in the roll press machine 60. In this embodiment, as shown in FIG. 9, creep removal is performed on the target pressing roll 62T in a state in which the electrode sheet 10 is not supported on the support roll 61 in the roll press machine 60, i.e., in a state in which the electrode sheet 10 is not disposed between the support roll 61 and a new target pressing roll 62T. In this state, the preload control unit 103 (see FIG. 6) of the control device 100 controls the driving of the cylinder drive device 73 (see FIG. 4) of the press pressure adjustment mechanism 70 to lower the target pressing roll 62T as shown in FIG. 9. As a result, the target pressing roll 62T comes into contact with the support roll 61. At this time, the pressing pressure of the target pressing roll 62T on the support roll 61 is, for example, 0.10 MPa to 0.80 MPa, preferably 0.15 MPa to 0.60 MPa, and particularly preferably 0.20 MPa to 0.40 MPa.

[0044] With the target pressing roll 62T in contact with the support roll 61, the preload control unit 103 controls the roll driver 74 to rotate the support roll 61. For example, the support roll 61 rotates in the direction of arrow R1. At this time, the target pressing roll 62T rotates in accordance with the rotation of the support roll 61. The target pressing roll 62T rotates in the direction of arrow R2. Because the target pressing roll 62T rotates while pressed against the support roll 61, a load is applied from the support roll 61 to the target pressing roll 62T. The preload control unit 103 rotates the support roll 61 for a load time T1 (see FIG. 8). As a result, as shown in FIG. 8, during the reference time NT1, the change in the elongation rate of the uncoated portion 12a stretched by the new target pressing roll 62T becomes equal to or less than the reference change amount NC1, and the elongation rate stabilizes. This allows creep removal of the new target pressing roll 62T. In this embodiment, the reference time NT1 and the reference change amount NC1 are stored in advance in the storage unit 101 of FIG.

[0045] The inventors of the present application conducted a test to determine the load time T1 required for applying a load to a new target pressing roll 62T until the elongation rate of the uncoated portion 12a stabilized. Here, a roll press machine 60 such as that shown in FIG. 4 was used to apply a load to the target pressing roll 62T by pressing the new target pressing roll 62T against a support roll 61 and rotating the support roll 61. The support roll 61 was rotated at a speed of 100 m / min, and the pressing pressure when the target pressing roll 62T pressed against the support roll 61 was 0.22 MPa. The load was applied eight times for five minutes. The results are shown in FIG. 8. In the graph of FIG. 8, the horizontal axis represents the number of times the target pressing roll 62T was loaded during the five-minute period (i.e., the total load time T1), and the vertical axis represents the elongation rate of the uncoated portion 12a of the electrode sheet 10 when the uncoated portion 12a was stretched using the target pressing roll 62T after each load application. This stretching ratio is calculated by the formula (B / A)×100, where A is the length of the unstretched coated portion 12b and B is the length of the stretched uncoated portion 12a.

[0046] As shown in Figure 8, when a new target pressing roll 62T was not previously loaded, i.e., the number of loads was zero, the elongation rate of the uncoated portion 12a was approximately 0.8%. When the target pressing roll 62T was loaded one to three times, the amount of change in the elongation rate of the uncoated portion 12a was large. Therefore, when the load was applied three times, i.e., the total load time T1 was 5 minutes x 3 times = 15 minutes, it is thought that the elongation rate of the uncoated portion 12a was unstable and the creep of the target pressing roll 62T was not eliminated.

[0047] On the other hand, after the fourth load application to the target pressing roll 62T, the elongation rate of the uncoated portion 12a was approximately 1.6%, and the change in the elongation rate of the uncoated portion 12a over a predetermined reference time NT1 was less than the reference change NC1. Therefore, by applying the load four or more times, i.e., by setting the total load time T1 to 5 minutes x 4 times = 20 minutes or more, the elongation rate of the uncoated portion 12a can be stabilized and the creep of the target pressing roll 62T can be eliminated. From the above, it can be seen that by setting the load time T1 for applying a load to a new target pressing roll 62T to 20 minutes or more, the creep of the target pressing roll 62T can be eliminated and the elongation rate of the uncoated portion 12a can be stabilized.

[0048] Next, in the stretching step S104 of FIG. 7, the uncoated portion 12a of the electrode sheet 10 is stretched. Here, the stretching control unit 105 of the control device 100 (see FIG. 6) stretches the uncoated portion 12a of the electrode sheet 10 by pressing a target pressing roll 62T against the uncoated portion 12a of the electrode sheet 10 while transporting the electrode sheet 10. The target pressing roll 62T used here is a roll that has been subjected to creep removal, and is a rubber roll to which a load has been applied so that the amount of change in the stretch rate of the uncoated portion 12a stretched by the target pressing roll 62T at a reference time NT1 is equal to or less than a reference change amount NC1. Here, after creep removal, the target pressing roll 62T is used in the stretching step S104 without being removed from the roll press machine 60.

[0049] In the stretching step S104, the stretching control unit 105 in FIG. 6 controls the cylinder driving device 73 and the roll driving device 74 as shown in FIG. 4. The cylinder driving device 73 lowers the rod 71a of the press cylinder 71. The cylinder driving device 73 lowers the rod 71a to a predetermined position. This causes the target pressing roll 62T to lower. At this time, the roll driving device 74 rotates the support roll 61. In this embodiment, as shown in FIG. 5, the roll driving device 74 rotates the support roll 61 in the direction of arrow R1. When the target pressing roll 62T lowers, the portion of the uncoated portion 12a sandwiched between the support roll 61 and the target pressing roll 62T is compressed.

[0050] As shown in FIG. 5, the rubber portion 61ab of the support roll 61 and the rubber portion 62ab of the target pressing roll 62T are compressed and deformed near the uncoated portion 12a. When the support roll 61 and the target pressing roll 62T rotate, the compressed portion of the rubber portion 61ab returns to its original shape due to elasticity. At this time, the portion of the rubber portions 61ab, 62ab that has moved near the uncoated portion 12a is compressed. Therefore, when the support roll 61 and the target pressing roll 62T rotate and the electrode sheet 10 is transported, the rubber portions 61ab, 62ab in the vicinity of the uncoated portion 12a repeatedly undergo elastic deformation along the circumferential direction of the support roll 61 and the target pressing roll 62T. In this way, the uncoated portion 12a is compressed and stretched.

[0051] Next, in the main pressing step S105 of Figure 7, after the stretching step S104, the electrode active material layer 14 (here, the coated portion 12b) of the electrode sheet 10 is pressed. In the main pressing step S105, 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.

[0052] As described above, in this embodiment, the method for treating an electrode sheet 10 includes a preparation step S101 and a stretching step S104, as shown in Fig. 7. In the preparation step S101, as shown in Fig. 2, a strip-shaped electrode sheet 10 is prepared, in which an electrode active material layer 14 is coated on a current collector 12 made of metal foil, the electrode sheet 10 having an uncoated portion 12a where the electrode active material layer 14 is not coated on the current collector 12. In the stretching step S104, as shown in Fig. 5, a pressing roll 62 (e.g., a target pressing roll 62T) is pressed against the uncoated portion 12a of the electrode sheet 10 while the electrode sheet 10 is being transported, thereby stretching the uncoated portion 12a. In the stretching step S104, a target pressing roll 62T is used such that the change in the stretch rate of the uncoated portion 12a stretched by the new target pressing roll 62T (see FIG. 8) is equal to or less than a predetermined reference change NC1 (see FIG. 8) during a predetermined reference time NT1 (see FIG. 8). In this way, the uncoated portion 12a can be stretched using the target pressing roll 62T that has been treated so as to stabilize the stretch rate of the uncoated portion 12a. This makes it possible to reduce variation in the degree of stretching of the uncoated portion 12a.

[0053] In this embodiment, when the pressing roll 62 used in the stretching step S104 is replaced with a new target pressing roll 62T in the replacement step S102 of Fig. 7, the target pressing roll 62T is replaced with a target pressing roll 62T that has been processed so that the amount of change in the stretch rate of the uncoated portion 12a stretched by the new pressing roll 62 at a reference time NT1 is equal to or less than a reference change amount NC1. Here, in the pre-load step S103 of Fig. 7, a load is applied to the pressing roll 62, thereby replacing it with the target pressing roll 62T. By performing such a replacement step S102, it is possible to replace the target pressing roll 62T with one that can stabilize the stretch rate of the uncoated portion 12a.

[0054] In this embodiment, in the pre-loading step S103 of Fig. 7, a load is applied to the target pressing roll 62T until the amount of change in the stretch rate of the uncoated portion 12a stretched by the target pressing roll 62T at a reference time NT1 becomes equal to or less than a reference change amount NC1, as shown in Fig. 8. The stretching step S104 of Fig. 7 uses the target pressing roll 62T to which a load is applied in the pre-loading step S103. By applying a load to the target pressing roll 62T in this way, creep can be eliminated, and as a result, the stretch rate of the uncoated portion 12a can be stabilized.

[0055] In the present embodiment, in the pre-loading step S103, a load is applied to the target pressing roll 62T by rotating the new target pressing roll 62T while pressing it against the support roll 61, which is an example of a pressed object prepared in advance, as shown in Fig. 9. In this way, by rotating the new target pressing roll 62T while pressing it against the support roll 61, a load can be applied to the target pressing roll 62T.

[0056] In this embodiment, the electrode manufacturing system 1 includes a preloading device and a stretching device. The preloading device and the stretching device are the same device, realized by a roll press machine 60. The roll press machine 60 applies a load to the target pressing roll 62T until the amount of change in the stretch rate of the uncoated portion 12a stretched by the target pressing roll 62T over a reference time NT1 becomes equal to or less than a reference change NC1. After the load is applied to the target pressing roll 62T, the roll press machine 60 presses the target pressing roll 62T against the uncoated portion 12a of the electrode sheet 10 to transport the electrode sheet 10. In the stretching step S104 in FIG. 7, the electrode sheet 10 is transported with the uncoated portion 12a of the electrode sheet 10 sandwiched between the target pressing roll 62T and a support roll 61, as shown in FIG. 5. In this way, using one roll press machine 60, a load can be applied to the target pressing roll 62T to remove creep, and the uncoated portion 12a of the electrode sheet 10 can be transported and stretched using the target pressing roll 62T that has been subjected to creep removal.

[0057] In the above embodiment, the preloading device and the stretching device are the same device, realized by the roll press machine 60. However, the preloading device and the stretching device may be separate devices. In this case, creep removal is performed by applying a load to a new target pressing roll 62T by the preloading device. After removing the target pressing roll 62T from the preloading device, the target pressing roll 62T from which creep has been removed may be attached to a stretching device (e.g., the roll press machine 60) and pressed against the uncoated portion 12a of the electrode sheet 10, thereby stretching the uncoated portion 12a.

[0058] In the above embodiment, when a load is applied to the new target pressing roll 62T, the object to be pressed against by the target pressing roll 62T is the support roll 61. However, the object to be pressed is not limited to a so-called roll, and may be, for example, a plate-like object as long as it can apply a load to the target pressing roll 62T.

[0059] In the above embodiment, creep removal is performed by applying a load to the new target pressing roll 62T by rotating the new target pressing roll 62T while pressing it against the support roll 61. However, the method of applying a load to the new target pressing roll 62T is not particularly limited. For example, a load may be applied to the new target pressing roll 62T by applying a physical impact to the new target pressing roll 62T. Examples of methods of applying a physical impact include hitting the target pressing roll 62T with a tool such as a hammer, or vibrating the target pressing roll 62T with a vibration device. Alternatively, a load may be applied to the new target pressing roll 62T by heating the new target pressing roll 62T with a heating device such as a heater. Creep removal of the target pressing roll 62T can also be performed using these methods of applying a load to the target pressing roll 62T.

[0060] 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.

[0061] As described above, this specification includes the disclosures set forth in the following sections. Section 1: a preparation step of preparing a strip-shaped electrode sheet in which an electrode active material layer is formed on a current collector made of a metal foil, the electrode sheet having an unformed portion on the current collector 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 electrode sheet; It encompasses In the stretching step, a rubber roll is used such that the change in the stretching rate of the unformed portion stretched by the rubber roll within a predetermined reference time is equal to or less than a predetermined reference change.

[0062] Section 2: Item 2. The electrode sheet processing method according to Item 1, further comprising a replacement step of replacing the rubber roll used in the stretching step with a replacement rubber roll that has been treated so that a change in the elongation rate of the unformed portion stretched by the replacement rubber roll at the reference time is equal to or less than the reference change.

[0063] Section 3: a pre-loading step of applying a load to the rubber roll until a change in the elongation rate of the unformed portion stretched by the rubber roll during the reference time period becomes equal to or less than the reference change, Item 3. The electrode sheet treatment method according to item 1 or 2, wherein the stretching step uses the rubber roll to which the load is applied in the pre-loading step.

[0064] Section 4: Item 4. The electrode sheet processing method according to Item 3, wherein in the pre-loading step, a load is applied to the rubber roll by rotating the rubber roll while the rubber roll is pressed against a previously prepared object to be pressed.

[0065] Section 5: Item 4. The electrode sheet treating method according to Item 3, wherein in the pre-loading step, a load is applied to the rubber roll by rotating the rubber roll while being pressed against another rubber roll.

[0066] Item 6: Item 6. The electrode sheet treating method according to Item 5, wherein in the stretching step, the electrode sheet is transported in a state in which the unformed portion of the electrode sheet is sandwiched between the rubber roll and the other rubber roll.

[0067] Section 7: Item 7. The method for treating an electrode sheet according to any one of Items 1 to 6, further comprising a main pressing step of pressing the electrode active material layer of the electrode sheet after the stretching step.

[0068] Section 8: a rubber roll that presses against an unformed portion of the electrode sheet where a current collector made of a metal foil is exposed, thereby stretching the unformed portion; and a pre-loading device that applies a load to the rubber roll until a change in an elongation rate of the unformed portion stretched by the rubber roll over a predetermined reference time period becomes equal to or less than a predetermined reference change amount. a stretching device that conveys the electrode sheet by pressing the rubber roll against the unformed portion of the electrode sheet after the pre-loading device has applied a load to the rubber roll; and An electrode manufacturing system comprising:

[0069] Section 9: Item 9. The electrode manufacturing system according to item 8, wherein the preloading device and the stretching device are the same device.

[0070] Section 10: Item 10. The electrode manufacturing system according to item 8 or 9, wherein the preloading device is provided with a pressed object that rotates while being pressed against the rubber roll.

[0071] Section 11: Item 10. An electrode manufacturing system according to item 8 or 9, wherein the preloading device includes another rubber roll that rotates while being pressed against the rubber roll.

[0072] Section 12: The conveying device is a support roll that supports the electrode sheet and sandwiches the electrode sheet together with the rubber roll; a conveying device that conveys the electrode sheet in a state in which the electrode sheet is sandwiched between the rubber roll and the support roll; Item 12. An electrode manufacturing system according to any one of items 8 to 11, comprising: [Explanation of symbols]

[0073] 1. Electrode manufacturing system 10 Electrode sheet 12 Current collector 12a Uncoated area (unformed area) 14 Electrode active material layer 15. Conveying equipment 60 Roll press machine (preloading device, stretching device) 61 Support roll (object to be pressed, other rubber roll) 62 Pressure roll (rubber roll) 62T Target pressure roll (rubber roll, replacement rubber roll) C1 change amount NC1 Reference Variation NT1 Reference Time S101 Preparation process S102 Replacement process S103 Preload process S104 Stretching process S105 Main press process

Claims

1. a preparation step of preparing a strip-shaped electrode sheet in which an electrode active material layer is formed on a current collector made of a metal foil, the electrode sheet having an unformed portion on the current collector 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 electrode sheet; It encompasses In the stretching step, a rubber roll is used such that the change in the stretching rate of the unformed portion stretched by the rubber roll within a predetermined reference time is equal to or less than a predetermined reference change.

2. 2. The electrode sheet processing method according to claim 1, further comprising a replacement step of replacing the rubber roll used in the stretching step with a replacement rubber roll that has been treated so that a change in the elongation rate of the unformed portion stretched by the replacement rubber roll at the reference time is equal to or less than the reference change.

3. a pre-loading step of applying a load to the rubber roll until a change in the elongation rate of the unformed portion stretched by the rubber roll during the reference time period becomes equal to or less than the reference change, The electrode sheet treating method according to claim 1 , wherein the stretching step uses the rubber roll to which the load has been applied in the pre-loading step.

4. 4. The electrode sheet processing method according to claim 3, wherein in the pre-loading step, a load is applied to the rubber roll by rotating the rubber roll while the rubber roll is pressed against a previously prepared object to be pressed.

5. 4. The electrode sheet treating method according to claim 3, wherein in the pre-loading step, the rubber roll is rotated while being pressed against another rubber roll, thereby applying a load to the rubber roll.

6. The electrode sheet treating method according to claim 5 , wherein in the stretching step, the electrode sheet is transported in a state in which the unformed portion of the electrode sheet is sandwiched between the rubber roll and the other rubber roll.

7. The electrode sheet treating method according to claim 1 , further comprising a pressing step of pressing the electrode active material layer of the electrode sheet after the stretching step.

8. a rubber roll that presses against an unformed portion of the electrode sheet where a current collector made of a metal foil is exposed, thereby stretching the unformed portion; and a pre-loading device that applies a load to the rubber roll until a change in an elongation rate of the unformed portion stretched by the rubber roll over a predetermined reference time period becomes equal to or less than a predetermined reference change amount. a stretching device that conveys the electrode sheet by pressing the rubber roll against the unformed portion of the electrode sheet after the pre-loading device has applied a load to the rubber roll; and An electrode manufacturing system comprising:

9. 9. The electrode manufacturing system of claim 8, wherein the preloading device and the stretching device are the same device.

10. 9. The electrode manufacturing system according to claim 8, wherein the preloading device includes a pressed object that rotates while being pressed against the rubber roll.

11. The electrode manufacturing system according to claim 8 , wherein the preloading device includes another rubber roll that rotates while being pressed against the rubber roll.

12. The stretching device a support roll that supports the electrode sheet and sandwiches the electrode sheet together with the rubber roll; a conveying device that conveys the electrode sheet in a state in which the electrode sheet is sandwiched between the rubber roll and the support roll; 9. The electrode manufacturing system of claim 8, comprising:

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