Electrode sheet manufacturing device

Abstract

To suppress variation in the amount of elongation of an unformed portion.SOLUTION: In an electrode sheet manufacturing device 100, a pressure roll is arranged so as to sandwich an unformed portion of an electrode sheet between the pressure roll and a support roll, excluding the region of the electrode sheet in which an active material layer is formed. The pressure roll is a rubber roll having at least the outer peripheral surface made of rubber, the rubber satisfying y1≥y2>0.8×y1, where y1 is a longitudinal elastic modulus at 25°C and y2 is a longitudinal elastic modulus at 60°C.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to 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 when the electrode sheet is roll-pressed, the uncoated portion is pressed with a pair of elastic rolls. By pressing the uncoated portion with a pair of elastic rolls, it is possible to apply a compressive force and a deforming force to the same location on the uncoated portion. This is said to enable the uncoated portion to be stretched while suppressing breakage of the uncoated portion. [Prior art documents] [Patent documents]

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

[0004] The present inventors have noticed that when the uncoated portion (unformed portion) is rolled during the roll-pressing of the electrode sheet in the above-described process, variations occur in the amount of elongation of the uncoated portion, and it is desirable to stabilize the amount of elongation of the uncoated portion. [Means for solving the problem]

[0005] The electrode sheet manufacturing apparatus disclosed herein is an apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along the length of the current collector at a predetermined position in the width direction, and an active material layer formed on the current collector in a portion excluding the unformed portion. The electrode sheet manufacturing equipment a conveying device that conveys the electrode sheet along a predetermined conveying path; a support roll that is disposed on the conveyance path and supports, along the width direction, a first surface of the electrode sheet that is conveyed along the conveyance path; a pressing roll disposed opposite the support roll and pressing the second surface of the electrode sheet; a pressing mechanism that presses the pressing roll against the support roll with the electrode sheet sandwiched therebetween; a drive device that drives the support roll to rotate; It is equipped with: The pressing roll is arranged to sandwich the unformed portion of the electrode sheet, excluding the portion on which the active material layer is formed, between the pressing roll and the support roll. The pressing roll is a rubber roll whose outer peripheral surface is made of rubber. When the Young's modulus of the rubber at 25°C is y1 and the Young's modulus of the rubber at 60°C is y2, the relationship y1 ≥ y2 > 0.8 × y1 is satisfied.

[0006] With this electrode sheet manufacturing device, deformation of the pressure roll is suppressed to a certain extent, and heat generation is suppressed, which makes it possible to stabilize the amount of elongation of the uncoated portion of the electrode sheet stretched by the EPS device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a flow diagram of the manufacturing method for an electrode sheet. [Figure 2] FIG. 2 is a schematic diagram of the electrode sheet 10. [Figure 3] FIG. 3 is a schematic diagram showing another embodiment of the electrode sheet 10. In FIG. [Figure 4] FIG. 4 is a schematic diagram of the electrode sheet manufacturing apparatus 100. [Figure 5] FIG. 5 is a front view of the EPS device 110 shown in FIG. 4 as seen from the conveyance direction of the electrode sheet 10. FIG. [Figure 6] FIG. 6 is a schematic side view showing the behavior of the pressure roll 112 when the uncoated portion 12a is rolled with EPS. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiments described herein are, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations are appropriately omitted. In this specification, expressions such as "X to Y" that indicate a numerical range mean "X or more and Y or less," unless otherwise specified.

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

[0010] <Electrode sheet 10> 2 is a schematic diagram of an electrode sheet 10. The electrode sheet 10 constitutes the positive electrode sheet or negative electrode sheet of an electrode body housed inside an electricity storage device. An electricity storage device refers to a device that can be repeatedly charged and discharged, and is a concept that encompasses so-called storage batteries (i.e., chemical batteries) such as lithium ion secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and other such batteries, as well as capacitors (i.e., physical batteries) such as electric double layer capacitors.

[0011] As shown in FIG. 2 , the electrode sheet 10 includes a current collector 12 and an active material layer 14. The current collector 12 is a member made of metal foil. The current collector 12 is a long, strip-shaped metal member. A metal material having a required conductivity can be used for the current collector 12. For example, aluminum or an aluminum alloy can be used for the positive electrode current collector foil. For example, copper or a copper alloy can be used for the negative electrode current collector foil. The active material layer 14 is coated at a predetermined position on the current collector 12. The active material layer 14 is formed on at least one surface of the strip-shaped current collector 12. In this embodiment, the active material layer 14 is formed on both surfaces of the current collector 12. The active material layer 14 is a layer containing an electrode active material. For example, a lithium transition metal composite oxide can be used for the positive electrode active material. For example, a carbon material, a silicon-based material, or a mixed oxide thereof can be used for the negative electrode active material. The active material layer may contain additives other than the electrode active material, such as a binder and a conductive material.

[0012] The electrode sheet 10 is formed by applying an electrode mixture slurry that will become the active material layer 14 to a current collector 12 and drying the applied slurry. The current collector 12 has uncoated portions 12a (unformed portions) and coated portions 12b. The uncoated portions 12a are portions of the current collector 12 that are not coated with the active material layer 14. The uncoated portions 12a are set along the length of the ends in the width direction of the electrode sheet 10. In this embodiment, the uncoated portions 12a are set at both ends in the width direction of the electrode sheet 10. The coated portions 12b are arranged between the uncoated portions 12a at both ends of the electrode sheet 10. The electrode mixture slurry is applied to the coated portions 12b. As a result, the active material layer 14 is formed in the coated portions 12b of the current collector 12. That is, the active material layer 14 is arranged between the uncoated portions 12a at both ends in the width direction of the electrode sheet 10. In this way, the electrode sheet preferably has a current collector 12 made of a long metal foil, an unformed portion (here, an uncoated portion 12a) set along the length of the current collector 12 at a predetermined position in the width direction, and an active material layer 14 formed on the current collector 12 in a portion other than the unformed portion.

[0013] FIG. 3 is a schematic diagram illustrating another embodiment of the electrode sheet 10. As shown in FIG. 3, the electrode sheet 10 may have an insulating protective layer 12c in the uncoated portion 12a adjacent to the coated portion 12b. This structure may be employed, for example, in an electrode sheet 10 used for a positive electrode. The provision of this protective layer 12c on an electrode sheet 10 used for a positive electrode can prevent short circuits between the positive electrode current collector foil and the negative electrode active material layer. The protective layer 12c contains an insulating inorganic filler. An example of the inorganic filler is insulating particles, such as ceramic particles of alumina. The protective layer 12c may contain, for example, a binder. The binder may be the same as the binder exemplified as one that may be contained in the positive electrode active material layer. Hereinafter, unless otherwise specified, reference will be made to FIGS. 2 and 3 for the components of the electrode sheet 10, as appropriate.

[0014] <Transportation process S1, measurement process S2, kneading process S3, coating process S4, drying process S5> In a conveying step S1 shown in FIG. 1, the electrode sheet 10 is conveyed. In the conveying step S1, the electrode sheet 10 is conveyed along a predetermined conveying path W1. In a weighing step S2, raw materials for the active material layer 14 (see FIG. 2) are weighed. The weighing can be achieved, for example, by a weighing device (not shown) having a balance, a load cell, or the like. The weighed raw materials for the active material layer 14 are mixed in a kneading step S3. The kneading step S3 can be achieved by a kneading device (not shown). The raw materials for the active material layer 14, which have been made into a slurry by the kneading device, are applied to the current collector 12 (see FIG. 2) in a coating step S4. The coating step S4 can be achieved by a coating device (not shown), such as a slit coater, gravure coater, die coater, or comma coater. In a drying step S5, the applied raw materials for the active material layer 14 in a slurry state are dried. The drying step S5 can be achieved by, for example, a drying device (not shown) that emits hot air or infrared rays.

[0015] <Roll press process S6> The roll pressing step S6 is a step of roll pressing the electrode sheet 10. Here, the substrate of the electrode sheet 10 is a metal foil. The electrode sheet 10 has a portion where the active material layer 14 is formed (coated portion 12b) and a portion where the active material layer 14 is not formed (uncoated portion 12a). The main purpose of the roll pressing step S6 is to adjust the active material layer 14 formed by coating to an appropriate density.

[0016] In the roll pressing step S6, the coated portion 12b is roll pressed to achieve an appropriate density for the active material layer 14. When the coated portion 12b is roll pressed, the current collector 12 of the substrate stretches in the coated portion 12b, but the pressure of the press is not directly transmitted to the uncoated portion 12a, making it difficult for the current collector 12 of the substrate to stretch. Therefore, if only the coated portion 12b is pressed, the elongation of the current collector 12 may vary between the coated portion 12b and the uncoated portion 12a. Large variations in the elongation of the current collector 12 between the coated portion 12b and the uncoated portion 12a may cause wrinkles to form in the electrode sheet 10. The uncoated portion 12a is cut into a predetermined shape in a subsequent process to form a tab. If wrinkles occur in the uncoated portion 12a, the tab may not be formed into the appropriate shape.

[0017] To prevent wrinkles from forming in the electrode sheet 10, it is preferable to stretch the current collector 12 with the uncoated portion 12a before or after roll-pressing the coated portion 12b. One technique for stretching the current collector 12 with the uncoated portion 12a is to press the uncoated portion 12a with a rubber roll. The technique of pressing the uncoated portion 12a with a rubber roll is appropriately referred to as EPS (Elasticity Powered Stretching). Furthermore, an apparatus for pressing the uncoated portion 12a with a rubber roll may be appropriately referred to as an EPS apparatus.

[0018] Fig. 4 is a schematic diagram of an electrode sheet manufacturing apparatus 100. The electrode sheet manufacturing apparatus 100 includes a conveying device 105 that conveys the electrode sheet 10 and a so-called EPS device 110. Fig. 4 shows a side view of the EPS device 110. Fig. 5 is a front view of the EPS device 110 shown in Fig. 4 as seen from the conveying direction of the electrode sheet 10.

[0019] As shown in Fig. 4, the conveying device 105 is a device that conveys the strip-shaped electrode sheet 10 along a predetermined conveying path W1. In the embodiment shown in Fig. 4, the electrode sheet 10 is supplied by an unwinding roll 105a, conveyed along the predetermined conveying path W1, and taken up by a take-up roll 105b. As shown in Fig. 4, the EPS device 110 is disposed midway along the conveying path W1 of the electrode sheet 10.

[0020] <EPS device 110> As shown in FIG. 4, the EPS device 110 is composed of a roll press machine that includes a support roll 111 and a pressure roll 112.

[0021] <Support Roll 111> As shown in FIG. 5, the support roll 111 is disposed on the transport path W1 and supports the first surface 10a (the lower surface in this embodiment) of the electrode sheet 10 transported along the transport path W1 in the width direction. In this embodiment, the support roll 111 is composed of a shaft 111a and a rubber 111b covering the outer circumferential surface of the shaft 111a. The shaft 111a may be made of a metal such as stainless steel. The rubber 111b may be made of a rubber material such as nitrile rubber (NBR). A drive unit 113 is attached to the rotation shaft 111a of the support roll 111. The shaft 111a of the support roll 111 is rotatably supported by a pair of support portions 111c. Although not shown, the pair of support portions 111c may include bearings that support the shaft 111a of the support roll 111. The drive unit 113 is a device that drives the support roll 111 to rotate. The driving device 113 is preferably a device that rotates the support roll 111 at a predetermined speed along the conveying direction of the conveying path W1. The driving device 113 is connected to the control device 120 and is configured to be able to appropriately change the rotation speed of the support roll 111. In the embodiment shown in FIG. 4, the support roll 111 is exemplified by a roll member composed of a shaft 111a and rubber 111b covering the outer circumferential surface of the shaft 111a, but is not limited to this. The support roll 111 may also be a rubber roll whose outer circumferential surface is made of rubber. Furthermore, in the embodiment shown in FIG. 4, the support roll 111 is a rubber roll whose surface is rubber, but the support roll 111 may also be a metal roll whose surface is metal.

[0022] <Pressing Roll 112> The pressing roll 112 is disposed opposite the support roll 111 and is a roll that presses the second surface 10b (the upper surface in this embodiment) of the electrode sheet 10. The pressing roll 112 is disposed so as to sandwich the uncoated portion 12a of the electrode sheet 10, excluding the coated portion 12b, between itself and the support roll 111. The pressing roll 112 is a rubber roll, at least the outer peripheral surface of which is made of rubber 112b.

[0023] In this embodiment, the pressing roll 112 is a roll in which rubber 112b is formed on the outer periphery of a shaft 112a made of metal such as stainless steel. As shown in FIGS. 4 and 5 , the rubber 112b is arranged on the shaft 112a at a predetermined interval along the axial direction so as to sandwich the uncoated portion 12a of the electrode sheet 10. The shaft 112a of the pressing roll 112 is supported by a roll chock 112c equipped with a bearing so that the pressing roll 112 rotates. The rotating shaft 112a of the pressing roll 112 is attached to a pressing mechanism 114 via the roll chock 112c, which presses the pressing roll 112 against the support roll 111. For example, a cylinder mechanism used in a press machine or the like can be used as the pressing mechanism 114. The pressing mechanism 114 is connected to a control device 120.

[0024] As shown in Figures 4 and 5, the uncoated portion 12a of the electrode sheet 10 is transported between a support roll 111 and a press roll 112. The support roll 111 rotates in the direction of arrow R1 shown in Figure 4. The press roll 112 is pressed against the support roll 111 with the uncoated portion 12a of the electrode sheet 10 sandwiched between them. The press roll 112 is driven to rotate in the direction of arrow R2 in accordance with the rotation of the support roll 111 and the running of the electrode sheet 10. The uncoated portion 12a of the electrode sheet 10 is transported while being sandwiched between the support roll 111 and the press roll 112. In such an EPS device, the surface of the press roll 112 is rubber. The press roll 112 is pressed against the support roll 111 while sandwiching the electrode sheet 10, and rotates while being partially deformed. The uncoated portions 12a of the electrode sheet 10 are conveyed while being sandwiched between the support roll 111 and the pressure roll 112, and are stretched in the conveyance direction during this process. In this way, in the EPS device 110, a tensile force is applied to the uncoated portions 12a of the electrode sheet 10 by the compressive force and elastic deformation of the rubber 112b of the pressure roll 112, and the uncoated portions 12a of the electrode sheet 10 can be stretched without applying a large tension to the electrode sheet 10.

[0025] Here, the thickness (radial height) of the rubber 112b of the pressing roll 112 may be, for example, 1 mm to 30 mm, and more preferably 5 mm to 20 mm. In this embodiment, the thickness (radial height) of the rubber 112b used in the pressing roll 112 is set to 10 mm. Unless otherwise specified, the thickness (radial height) of the rubber 112b of the pressing roll 112 is not particularly limited.

[0026] The present inventors have discovered that variations in elongation occur when the uncoated portion 12a is rolled using EPS. Investigation into the cause of this phenomenon revealed that the rubber 112b of the pressure roll 112 generates heat during EPS treatment. Figure 6 is a schematic side view showing the behavior of the pressure roll 112 when the uncoated portion 12a is rolled using EPS. When the rubber 112b generates heat, the elastic modulus of the rubber 112b of the pressure roll 112 decreases, resulting in increased deformation. When the elastic modulus of the rubber 112b decreases and deformation increases, a bulge 112b1 (a protrusion on the outer surface) may occur on the surface of the rubber 112b, as shown in Figure 6. In the embodiment shown in Figure 6, the outer surface of the support roll 111 is rubber 111b. When the outer surface of the support roll 111 is made of rubber 111b, a bulge 111b1 (a protrusion on the outer surface) may also occur in the rubber 111b on the outer surface of the support roll 111, as shown in FIG.

[0027] The bulges 111b1 and 112b1 tend to occur on the outer peripheral surfaces of the pressure roll 112 and the support roll 111, on the side where the uncoated portion 12a of the electrode sheet 10 is sandwiched (upstream of the pressure roll 112). The inventors believe that the bulges 111b1 and 112b1 occur as follows: Because the rubber 111b and 112b are viscoelastic, they attempt to return to their original shape when subjected to a certain amount of strain. In the Maxwell model of viscoelasticity, the spring corresponds to the elastic term and the dashpot corresponds to the viscous term. The elastic term returns quickly, but the viscous term takes time to return to its original shape. As a result, bulges (bulges 111b1 and 112b1) occur on the side where the uncoated portion 12a of the electrode sheet 10 is sandwiched. The ratio of elasticity to viscosity can be changed by changing the rubber compounding.

[0028] In EPS, the support roll 111 and pressure roll 112 rotate and continuously press the uncoated portion 12a of the electrode sheet 10. During this process, the elasticity and viscosity of dynamic viscoelasticity (when continuous strain is applied) are expressed as the storage tensile modulus (E1) and loss tensile modulus (E2). The ratio E2 / E1 is called the loss tangent (loss factor) and is expressed as tan δ. The loss tangent (tan δ) indicates how much energy a material absorbs (converts to heat) when it deforms. The complex modulus E* can be expressed as E1 + iE2. The loss tangent (tan δ) of the support roll 111 and pressure roll 112 is preferably 0.03 to 0.20, more preferably 0.03 to 0.10, in terms of tan δ at 30°C (i.e., tan δ(@30°C)).

[0029] According to the inventor's research, high viscosity generates a lot of heat. Furthermore, high viscosity generates a lot of strain. Creating rubber with low viscosity reduces heat generation in the rubber. This can suppress the increase in viscosity due to heat generation. From this perspective, the inventor considered optimizing the viscosity of the rubber 112b of the pressure roll 112 in the operating temperature range of the EPS device and reducing the temperature dependence of the Young's modulus. By reducing the temperature dependence of the Young's modulus of the rubber 112b of the pressure roll 112 in the operating temperature range of the EPS device, the temperature rise in the EPS device is suppressed, the viscosity increase is suppressed, and the elongation rate of the aluminum foil can be stabilized. While the pressure roll 112 is described here, the same applies to the support roll 111 if its outer surface is made of rubber.

[0030] The electrode sheet 10 used here is not particularly limited. The uncoated portion 12a of the electrode sheet 10 used for the positive electrode is made of, for example, aluminum foil with a thickness of approximately 10 to 15 μm. On the other hand, copper foil is used for the negative electrode. Due to this difference in the collector foil, the electrode sheet 10 used for the positive electrode is more prone to tearing than the electrode sheet for the negative electrode. Here, the process of stretching the uncoated portion 12a of the electrode sheet 10 used for the positive electrode using EPS was the main subject of evaluation. However, the rubber material used for the pressing roll 112 of the EPS device and the material of the collector foil (uncoated portion 12a) of the electrode sheet 10 are not particularly limited unless otherwise specified.

[0031] According to the findings of the present inventors, the rubber 112b generates heat during processing with EPS, which changes the size of the bulge 112b1 that appears on the surface of the rubber 112b. The larger the bulge 112b1, the greater the elongation of the uncoated portion 12a of the electrode sheet 10 tends to be.

[0032] The electrode sheet manufacturing apparatus 100 proposed here is configured so that the rubber 112b on the outer surface of the pressing roll 112 satisfies y1 ≧ y2 > 0.8 × y1, where y1 is the modulus of longitudinal elasticity at 25°C and y2 is the modulus of longitudinal elasticity at 60°C. In other words, by configuring the rubber 112b on the outer surface of the pressing roll 112 to satisfy y1 ≧ y2 > 0.8 × y1, the modulus of longitudinal elasticity of the pressing roll 112 is stabilized in the temperature range used in the EPS device (25 to 60°C), and it can be expected that the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device will be stabilized.

[0033] The electrode sheet manufacturing apparatus 100 generates heat during use, generally within the range of room temperature to 60°C. In the electrode sheet manufacturing apparatus 100 proposed here, the rubber 112b on the outer surface of the pressing roll 112 has a longitudinal elastic modulus y2 at 60°C that is equal to or less than the longitudinal elastic modulus y1 at 25°C and is greater than 0.8 × y1. In other words, the temperature dependence of the longitudinal elastic modulus of the rubber 112b on the outer surface of the pressing roll 112 should be small in the range of 25°C to 60°C. This stabilizes the size of the bulge in the EPS operating temperature range. This stabilizes the elongation of the uncoated portion 12a of the electrode sheet 10. From this perspective, the rubber 112b on the outer surface of the pressing roll 112 should preferably have a small temperature dependence of the longitudinal elastic modulus in the range of 25°C to 60°C. More preferably, y2 > 0.85 × y1, and even more preferably, y2 > 0.90 × y1.

[0034] Furthermore, the longitudinal elastic modulus y1 of the rubber 112b at 25° C. is preferably 20 MPa≦y1≦26 MPa, so that the rubber 112b can exert the elastic force required for the EPS treatment and appropriately stretch the uncoated portion 12a of the electrode sheet 10.

[0035] Furthermore, the hardness of the rubber 112b at 25° C. is preferably 92±3. This allows the rubber 112b to be kept small in deformation during EPS processing, to keep heat generation in the rubber 112b small, and to keep the bulge 112b1 small.

[0036] Here, suitable physical properties of the rubber 112b of the pressing roll 112 when processing the uncoated portion of the positive electrode are exemplified. A pressing roll equipped with rubber of similar physical properties can also be used when processing the uncoated portion (unformed portion) of the negative electrode. According to the inventor's knowledge, as described above, it is desirable to use rubber that is hard and less susceptible to the effects of viscosity for the pressing roll. When the uncoated portion of the negative electrode is copper foil, copper is more easily stretched than aluminum, so the inventor believes that it is desirable to use rubber that is equivalent to or less susceptible to the effects of viscosity than when processing aluminum (in other words, less susceptible to bulging).

[0037] The EPS device 110 is preferably configured so that the temperature of the rubber 112b is kept below a predetermined temperature of 60°C or less when the electrode sheet 10 is sandwiched between the pressure roll 112 and the support roll 111 to stretch the uncoated portion 12a. From this perspective, the EPS device 110 may employ a cooling mechanism, such as blowing cold air onto the pressure roll 112. The inventors have produced a prototype EPS device 110 for verification. Here, the uncoated portion 12a of the electrode sheet 10 was rolled while conveying 12,000 m of the electrode sheet 10 at 100 m / min. In the rolling of the uncoated portion 12a of the electrode sheet 10, the pressing force of the pressure roll 112 was appropriately adjusted.

[0038] Here, the uncoated portion 12a of the electrode sheet 10 is an aluminum foil having a thickness of 12 μm. The pressing force of the pressing roll 112 was determined by setting the output of the cylinder mechanism serving as the pressing mechanism 114 to 2900 N to 2600 N. The output of the cylinder mechanism serving as the pressing mechanism 114 was set to approximately 0.14 MPa to approximately 0.12 MPa in terms of the surface pressure of the pressing roll 112. Specifically, the pressing force of the pressing roll 112 was determined by setting the output of the cylinder mechanism to 2900 N in the early stages of processing, which was approximately 0.14 MPa in terms of the surface pressure of the pressing roll 112. Furthermore, as time passes during the EPS processing, the pressing roll 112 generates heat. In response to the heat generated by the pressing roll 112, the output of the cylinder mechanism was reduced to 2600 N, which was approximately 0.12 MPa in terms of the surface pressure of the pressing roll 112. In the test, when 6000 m of electrode sheet 10 was transported at 100 m / min, the temperature of the pressing roll 112 rose from 25°C to approximately 40°C, and then the temperature increase slowed down and rose to approximately 41°C. The process was then stopped, and the remaining 6000 m of electrode sheet 10 was transported at 100 m / min to perform EPS processing. Similarly, the temperature of the pressing roll 112 rose to approximately 40°C, and then the temperature increase slowed down and finally rose to approximately 43°C.

[0039] Thus, in the EPS device 110, when the electrode sheet 10 is sandwiched between the pressure roll 112 and the support roll 111 to stretch the uncoated portion 12a, it is preferable that the temperature of the rubber 112b be kept below a predetermined temperature of 60°C or less. In the EPS device 110, the rubber 112b on the outer surface of the pressure roll 112 is preferably configured to satisfy y1 ≥ y2 > 0.8 × y1, where y1 is the modulus of longitudinal elasticity at 25°C and y2 is the modulus of longitudinal elasticity at 60°C. This stabilizes the modulus of longitudinal elasticity of the pressure roll 112 during use in the EPS device 110. In other words, the pressure roll 112 during use in the EPS device 110 has a stable modulus of longitudinal elasticity despite temperature increases. Furthermore, deformation of the pressure roll 112 is suppressed to a certain extent, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized. Note that the description here is directed to the pressing roll 112. As shown in FIG. 6, when the outer surface of the support roll 111 is made of rubber 111b, it is preferable that the support roll 111 is also made of the same rubber material as the pressing roll 112. This is expected to minimize heat generation in the rubber 111b of the support roll 111 and minimize bulges 111b1. Through tests, the inventors of the present application changed the composition of the rubber used for the support roll 111 and the pressing roll 112, and used rubbers with different physical properties for the support roll 111 and the pressing roll 112. As a result, it was confirmed that by appropriately adjusting the physical properties of the rubber as described above, deformation of the pressing roll 112 is suppressed to a certain degree and heat generation is suppressed.

[0040] Example Table 1 lists specific physical property values ​​for one example of a rubber material used in the pressing roll 112 of the EPS device 110 proposed herein. According to the inventor's findings, by using rubber exhibiting the physical properties shown in Table 1 for the pressing roll 112, deformation of the pressing roll 112 is suppressed to a certain degree, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized. Here, the rubber used for the pressing roll 112 is a natural rubber (NBR)-based compound. However, the type of rubber used for the pressing roll 112 is not limited to this, and rubbers having similar physical properties can be used. From this perspective, the rubber used for the pressing roll 112 may be, for example, a urethane-based rubber, an ethylene propylene diene rubber (EPD)M-based rubber, or a fluorine-based compound rubber.

[0041] [Table 1]

[0042] <Hardness of rubber 112b> In the example shown in Table 1, the hardness of the rubber 112b used in the pressing roll 112 was 92 (Hs) in a durometer (type A) conforming to the JIS standard. According to the knowledge of the present inventors, the hardness of the rubber 112b used in the pressing roll 112 may be, for example, about 92±3 (Hs).

[0043] <Tensile strength of rubber 112b> In the example shown in Table 1, the tensile strength of the rubber 112b used in the pressing roll 112 was 27 (MPa). According to the knowledge of the present inventors, the hardness of the rubber 112b used in the pressing roll 112 may be, for example, about 92±3 (Hs). The tensile strength can be measured using an autograph (tension / compression tester). The measurement temperature is preferably, for example, room temperature (25°C). Any commercially available device can be used for the autograph.

[0044] <Elongation rate of rubber 112b> In the example shown in Table 1, the elongation percentage (%) of the rubber 112b used in the pressing roll 112 was 400(%). According to the knowledge of the present inventors, the elongation percentage (%) of the rubber 112b used in the pressing roll 112 may be, for example, about 370 to 450%. The elongation percentage can be measured using an autograph. Again, it is preferable that the measurement temperature be room temperature (25°C).

[0045] <Tear strength of rubber 112b> In the example shown in Table 1, the tear strength (kN / m) of the rubber 112b used in the pressing roll 112 was 50 kN / m. According to the inventor's findings, the tear strength (kN / m) of the rubber 112b used in the pressing roll 112 may be, for example, about 45 kN / m or more. If the tear strength of the rubber 112b is about 45 kN / m or more, the rubber 112b used in the pressing roll 112 is less likely to break during EPS processing. The tear strength (kN / m) can be measured using an autograph. Again, it is preferable to evaluate the measurement at room temperature (25°C).

[0046] <Modulus of longitudinal elasticity> In the example shown in Table 1, the Young's modulus (MPa) of the rubber 112b used in the pressing roll 112 was 23 MPa at 25°C, 17 MPa at 60°C, 14 MPa at 80°C, 12 MPa at 100°C, and 11 MPa at 120°C. The Young's modulus of the rubber 112b used in the pressing roll 112 can be measured using an autograph. Here, too, the measurement temperature is preferably room temperature (25°C). The Young's modulus of the rubber 112b used in the pressing roll 112 is temperature-dependent, as shown in Table 1. To achieve the effect of stabilizing the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110, it is preferable that the Young's modulus be stable in the operating temperature range of approximately 25°C to 60°C. From this perspective, according to the inventor's knowledge, the modulus of longitudinal elasticity (MPa) of the rubber 112b used in the pressure roll 112 should be, for example, about 23±3 MPa at 25°C, and at 60°C, it should be 80% or more, more preferably 90% or more, of the modulus of longitudinal elasticity at 25°C.

[0047] <Compression set, linear expansion coefficient (10 -4 ℃)〉 In the example shown in Table 1, the compression set of the rubber 112b used in the pressing roll 112 was 24 at 30°C for 72 hours and 43 at 60°C for 72 hours. Here, the compression set is defined by the permanent compression set (JIS K6262). In addition, the linear expansion coefficient (10 -4 The linear expansion coefficient (10 -4 °C) is determined by a thermal expansion coefficient measuring device. Here, the compression set and linear expansion coefficient (10 -4 ° C.) is given as an example. Any commercially available device can be used as the thermal expansion coefficient measuring device.

[0048] According to the knowledge of the inventors, the compression set and linear expansion coefficient (10 -4 °C) is considered to be less important than hardness, tensile strength, elongation, tear strength, and other physical properties in terms of achieving the effect of stabilizing the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110. It is sufficient if the temperature is within the range of general physical properties of the rubber 112b used in the pressing roll 112.

[0049] Here, the physical properties of the rubber 112b used in the pressing roll 112 can vary depending on the manufacturing conditions, the amount of additives added, the vulcanization conditions, and the like. The target value column in Table 1 lists the range of physical properties that the inventors consider to be preferable for the rubber 112b used in the pressing roll 112. According to the inventors' findings, by using rubber exhibiting the physical properties shown in Table 1 for the pressing roll 112, deformation of the pressing roll 112 is suppressed to a certain degree, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized.

[0050] As described above, according to the inventor's findings, by using rubber exhibiting the physical properties shown in Table 1 for the pressing roll 112 of the EPS device 110, deformation of the pressing roll 112 is suppressed to a certain degree, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized. Rubber exhibiting the above physical properties is special, but can be obtained by specifying the physical properties and ordering from a rubber manufacturer. An example of a rubber manufacturer that can produce rubber exhibiting the above physical properties is Chugoku Rubber Industry Co., Ltd.

[0051] As described above, the pressing roll 112 of the EPS device 110 is a rubber roll having at least an outer peripheral surface made of rubber 112b, and it is preferable that the rubber 112b has a Young's modulus at 25°C of y1 and a Young's modulus at 60°C of y2 such that y1 ≥ y2 > 0.8 × y1. By using such a pressing roll 112 in the EPS device 110, deformation of the pressing roll 112 is suppressed to a certain extent, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized.

[0052] From this perspective, the longitudinal elastic modulus y1 at 25°C of the rubber 112b used in the pressing roll 112 is preferably 20 MPa≦y1≦26 MPa. Furthermore, the hardness (JIS-A) of the rubber at 25°C is preferably 92±3 (Hs). In this case, too, deformation of the pressing roll 112 is suppressed to a certain extent, and heat generation is suppressed. As a result, the amount of elongation of the uncoated portion 12a of the electrode sheet 10 stretched by the EPS device 110 can be stabilized.

[0053] Furthermore, the EPS device 110 is preferably configured so that when the uncoated portion 12a of the electrode sheet 10 is sandwiched between the pressure roll 112 and the support roll 111 and the uncoated portion 12a is stretched, the temperature rise of the rubber is suppressed to a predetermined temperature of 60° C. or less. From this perspective, methods include blowing a cooling gas (for example, air) onto the pressure roll 112, or attaching heat dissipation means such as cooling fins or heat sinks to the side of the pressure roll 112.

[0054] Here, reference is made to the rubber material used for the pressing roll 112 of the EPS device 110. As shown in FIG. 5 , like the pressing roll 112, rubber 111b may also be formed on the surface of the support roll 111 of the EPS device. When rubber 111b is formed on the surface of the support roll 111 of the EPS device, it is preferable that the rubber 111b used for the support roll 111 and the rubber 112b used for the pressing roll 112 have the same physical properties. For example, it is preferable that the rubber 111b used for the support roll 111 and the rubber 112b used for the pressing roll 112 are made of the same material. In other words, it is preferable that the rubber 111b used for the support roll 111 and the rubber 112b of the pressing roll 112 have the same physical properties and composition. This allows the pressing roll 112 and the support roll 111 to sandwich the uncoated portion 12a of the electrode sheet 10 and stretch the uncoated portion 12a, so that a tensile force can be applied equally to both sides of the electrode sheet 10. This allows the uncoated portion 12a to be stretched appropriately.

[0055] 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.

[0056] As described above, this specification includes the disclosures set forth in the following sections.

[0057] Section 1: 1. An electrode sheet manufacturing apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along a length direction of the current collector at a predetermined position in a width direction thereof, and an active material layer formed on a portion of the current collector excluding the unformed portion, a conveying device that conveys the electrode sheet along a predetermined conveying path; a support roll that is disposed on the transport path and supports, along a width direction, a first surface of the electrode sheet that is transported along the transport path; a pressing roll disposed opposite the support roll and pressing a second surface of the electrode sheet; a pressing mechanism that presses the pressing roll against a support roll with the electrode sheet sandwiched therebetween; a drive device that drives the support roll to rotate; Equipped with The electrode sheet is a current collector made of metal foil; an active material layer coated on a predetermined position of the current collector; an uncoated portion of the current collector that is not coated with the active material layer; and the pressing roll is disposed so as to sandwich the unformed portion of the electrode sheet, excluding a portion on which the active material layer is formed, between the pressing roll and the support roll; the pressure roll is a rubber roll having at least an outer peripheral surface made of rubber, The rubber has a longitudinal elastic modulus of y1 at 25°C and a longitudinal elastic modulus of y2 at 60°C, and the relationship y1 ≧ y2 > 0.8 × y1 is satisfied. Electrode sheet manufacturing equipment.

[0058] Section 2: Item 2. The electrode sheet manufacturing apparatus according to Item 1, wherein the rubber has a longitudinal elastic modulus y1 at 25°C of 20 MPa ≦ y1 ≦ 26 MPa.

[0059] Section 3: Item 3. The electrode sheet manufacturing apparatus according to Item 1 or 2, wherein the rubber has a hardness (JIS-A) of 92±3 (Hs) at 25°C.

[0060] Section 4: 4. The electrode sheet manufacturing apparatus according to claim 1, wherein the apparatus is configured such that when the unformed portion of the electrode sheet is sandwiched between the pressure roll and the support roll to stretch the unformed portion, a temperature rise of the rubber is suppressed to a predetermined temperature of 60°C or less.

[0061] Section 5: 5. The electrode sheet manufacturing apparatus according to any one of items 1 to 4, wherein the support roll is a rubber roll having at least an outer peripheral surface made of rubber.

[0062] Item 6: Item 6. The electrode sheet manufacturing apparatus according to Item 5, wherein the rubber used for the support roll and the rubber used for the pressure roll have the same physical properties. [Explanation of symbols]

[0063] 10 Electrode sheet 12 Current collector 12a Uncoated area (unformed area) 12b Coating Department 12c protective layer 14 Active material layer 100 Electrode sheet manufacturing equipment 105 Transport equipment 105a Unwinding roll 105b Winding roll 110 EPS equipment 111 Support Roll 111a Axis (rotation axis) of support roll 111 111b Rubber of support roll 111 111b1 Bulge 111c Support part 112 Pressing roll 112a: Shaft (rotation shaft) of the pressure roll 112 112b Rubber of the pressure roll 112 112b1 Bulge 112c Roll Chock 113 Drive unit 114 Pressing mechanism 120 Control device W1 transport route

Claims

1. 1. An electrode sheet manufacturing apparatus for manufacturing an electrode sheet having a current collector made of a long metal foil, an unformed portion set along a length direction of the current collector at a predetermined position in a width direction thereof, and an active material layer formed on a portion of the current collector excluding the unformed portion, a conveying device that conveys the electrode sheet along a predetermined conveying path; a support roll disposed on the transport path and configured to support, along a width direction, a first surface of the electrode sheet transported along the transport path; a pressing roll disposed opposite the support roll and pressing a second surface of the electrode sheet; a pressing mechanism that presses the pressing roll against a support roll with the electrode sheet sandwiched therebetween; a drive device that drives the support roll to rotate; Equipped with the pressing roll is disposed so as to sandwich the unformed portion of the electrode sheet, excluding a portion on which the active material layer is formed, between the pressing roll and the support roll; the pressure roll is a rubber roll having at least an outer peripheral surface made of rubber, The rubber has a longitudinal elastic modulus at 25°C of y1 and a longitudinal elastic modulus at 60°C of y2, and the relationship y1 ≥ y2 > 0.8 × y1 is satisfied. Electrode sheet manufacturing equipment.

2. 2. The electrode sheet manufacturing apparatus according to claim 1, wherein the longitudinal elastic modulus y1 of the rubber at 25° C. satisfies 20 MPa≦y1≦26 MPa.

3. 2. The electrode sheet manufacturing apparatus according to claim 1, wherein the rubber has a hardness (JIS-A) of 92±3 (Hs) at 25°C.

4. 2. The electrode sheet manufacturing apparatus according to claim 1, wherein the pressure roll and the support roll are configured to suppress a temperature rise of the rubber to a predetermined temperature of 60°C or less when the unformed portion of the electrode sheet is sandwiched between the pressure roll and the support roll to stretch the unformed portion.

5. 2. The electrode sheet manufacturing apparatus according to claim 1, wherein the support roll is a rubber roll having at least an outer peripheral surface made of rubber.

6. The electrode sheet manufacturing apparatus according to claim 5 , wherein the rubber used for the support roll and the rubber used for the pressure roll have the same physical properties.

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