Electrode manufacturing method

Abstract

To provide a method for manufacturing an electrode capable of suppressing quality deterioration.SOLUTION: A method for manufacturing an electrode includes the steps of: preparing a precursor sheet including a metal foil having a longitudinal direction in a first direction and a coated part and an uncoated part arranged on the metal foil; pressing the coated part in a thickness direction while transporting the precursor sheet in the first direction; and pressing the uncoated part in the thickness direction while transporting the precursor sheet in the first direction before or after the coated part pressing step. The uncoated part is arranged in an end part of the coated part in a direction orthogonal to the first direction. In the uncoated part pressing step, the method performs roll-press while applying compressive force for pressing the uncoated part in the thickness direction using a pair of elastic rolls having a shaft body and an elastic body covering the shaft body. The method uses elastic rolls A and B as a pair of elastic rolls. A Young's modulus X of the elastic body in the elastic roll A is lower than a Young's modulus Y of the elastic body in the elastic body B.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode. [Background technology]

[0002] As a method for manufacturing an electrode, a method is known in which a sheet in which an electrode mixture is applied onto a long metal foil is rolled.

[0003] For example, Patent Document 1 discloses a method for pressing a battery electrode having a coated portion coated with an electrode active material and an uncoated portion not coated with the electrode active material. Patent Document 2 also discloses a roll pressing method using a roll press machine equipped with a wrinkle prevention device that suppresses the occurrence of wrinkles that occur in the coated and uncoated portions of the electrode plate during roll pressing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5760366 [Patent Document 2] Japanese Patent Application Publication No. 2019-102172 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when a sheet having coated and uncoated areas is pressed, the coated and uncoated areas may be pressed separately to adjust the difference in elongation so as to prevent wrinkles from occurring. Also, the uncoated areas may be roll-pressed using an elastic roll to prevent breakage of the uncoated areas when pressed.

[0006] The inventors have found that when an elastic roll is used to press an uncoated portion, if the elastic roll runs over the coated portion due to meandering or the like, there is a risk of streaks appearing in the coated portion or the coated portion breaking, which may result in a deterioration in the quality of the resulting electrode.

[0007] The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a method for manufacturing an electrode that can suppress deterioration in quality. [Means for solving the problem]

[0008] [1] The method includes a preparation step of preparing a precursor sheet having a metal foil having a longitudinal direction in a first direction and a coated portion and an uncoated portion arranged on the metal foil, a coated portion pressing step of pressing the coated portion in a thickness direction while conveying the precursor sheet in the first direction, and an uncoated portion pressing step of pressing the uncoated portion in the thickness direction while conveying the precursor sheet in the first direction before or after the coated portion pressing step, wherein the coated portion contains an electrode material including at least an active material, and the uncoated portion is a method for manufacturing an electrode, the method including: a step of pressing an uncoated portion of a sheet of paper, the uncoated portion not containing the electrode material and arranged at an end of the coated portion in a direction perpendicular to the first direction; a step of pressing the uncoated portion of the sheet of paper using a pair of elastic rolls each having a shaft and an elastic body covering the shaft, while applying a compressive force that presses the uncoated portion in the thickness direction; a step of pressing an uncoated portion of a sheet of paper using a pair of elastic rolls each having a shaft and an elastic body covering the shaft; a step of pressing an uncoated portion of the ...

[0009] [2] [1] A method for manufacturing an electrode, wherein the length of the elastic body of the elastic roll A is shorter than the length of the elastic body of the elastic roll B in the axial direction of the shaft body.

[0010] [3] The method for manufacturing an electrode described in [1] or [2], wherein, when observed from the thickness direction, the elastic body of the elastic roll A has a first end and a second end positioned outward from the first end in the axial direction of the shaft, and when observed from the thickness direction, the position of the first end overlaps with the position of the elastic body of the elastic roll B.

[0011] [4] The method for manufacturing an electrode according to any one of [1] to [3], wherein the elastic roll A is arranged so that the elastic body is in contact with the precursor sheet at a position overlapping with the uncoated portion when observed from the thickness direction, and is arranged so that the elastic roll A is not in contact with the precursor sheet at a position overlapping with the coated portion when observed from the thickness direction, and the elastic roll B is arranged so that the elastic body is in contact with the precursor sheet at a position overlapping with the uncoated portion when observed from the thickness direction, and is arranged so that the elastic body is in contact with the precursor sheet at a position overlapping with the coated portion when observed from the thickness direction. [Effects of the Invention]

[0012] The present disclosure provides an effect of providing a method for manufacturing an electrode that can suppress deterioration in quality. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a flow diagram illustrating a method for manufacturing an electrode according to the present disclosure. [Figure 2] FIG. 1 is a diagram illustrating the mechanism in the present disclosure. [Figure 3] FIG. 2 is a schematic plan view illustrating a precursor sheet according to the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating an uncoated portion pressing step in the present disclosure. [Figure 5] FIG. 1 is a diagram showing the results of Experimental Example 1. [Figure 6] FIG. 10 is a diagram showing the results of Experimental Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] The method for manufacturing an electrode according to the present disclosure will be described in detail below. In this specification, when expressing an aspect in which another member is disposed relative to a certain member, the term "above" includes both a case in which another member is disposed directly above the certain member so as to be in contact with the certain member, and a case in which another member is disposed above the certain member via another member, unless otherwise specified.

[0015] FIG. 1 is a flow diagram showing an example of a method for manufacturing an electrode according to the present disclosure. In FIG. 1, first, a precursor sheet is prepared (preparation step) having a metal foil having a longitudinal direction in a first direction and a coated portion and an uncoated portion disposed on the metal foil. The coated portion contains an electrode material including at least an active material. The uncoated portion does not contain the electrode material and is disposed at an end of the coated portion in a direction perpendicular to the first direction. Next, while the precursor sheet is conveyed in the first direction, the coated portion is pressed in the thickness direction (coated portion pressing step). Then, while the precursor sheet is conveyed in the first direction, the uncoated portion is pressed in the thickness direction (uncoated portion pressing step). Note that, although the uncoated portion pressing step is performed after the coated portion pressing step in FIG. 1, it may be performed before the coated portion pressing step. Furthermore, in the uncoated portion pressing step, roll pressing is performed using a predetermined pair of elastic rolls. Furthermore, elastic roll A and elastic roll B are used as the pair of elastic rolls, and the Young's modulus X of the elastic body in elastic roll A is lower than the Young's modulus Y of the elastic body in elastic roll B. Here, in the present disclosure, the "thickness direction" is synonymous with the lamination direction of the metal foil and the coated portion.

[0016] According to the present disclosure, since the Young's modulus X of the elastic body of elastic roll A is lower than the Young's modulus Y of the elastic body of elastic roll B, even if the elastic roll runs onto the coating section due to meandering or the like, breakage or the like can be suppressed, and deterioration in the quality of the obtained electrode can be suppressed.

[0017] A known method for manufacturing electrodes is to press a precursor sheet in which an electrode composite is applied onto a metal foil (current collector foil). Furthermore, the presence or absence of the electrode composite can result in a difference in elongation between the coated and uncoated portions of the metal foil after pressing, potentially resulting in wrinkles in the electrode. Regarding this issue, as in Patent Document 1 mentioned above, the coated and uncoated portions are pressed separately to prevent wrinkles from forming. Furthermore, when pressing the uncoated portion (metal foil), a pair of elastic rolls may be used to perform roll pressing while applying a compressive force in the thickness direction. By performing such roll pressing, it is possible to apply a deformation force resulting from deformation of the elastic body to the uncoated portion in addition to the compressive force. This can effectively prevent, for example, breakage of the uncoated portion.

[0018] Here, metal foils generally contain inclusions of hard tissues that are harder than the material of the metal foil. The inclusion of hard tissues can, for example, increase the strength of the metal foil. When a tensile force (horizontal force) is applied to stretch the metal foil, the hard tissues do not deform, but the surrounding metal foil, which is softer than the hard tissues, deforms. As a result, voids are formed around the hard tissues. When multiple voids connect with each other, breakage is likely to occur. In contrast, in the present disclosure, a pair of elastic rolls is used to perform roll pressing while applying a compressive force in the thickness direction. This allows the uncoated portion to be subjected to a deformation force resulting from the deformation of the elastic body, along with the compressive force. As a result, it is believed that the generation of voids around the hard tissues can be suppressed. The compressive force corresponds to a force in the thickness direction, and the deformation force corresponds to a force perpendicular to the thickness direction. In other words, the deformation force acts in the same direction as the tensile force and stretches the metal foil in the same way as the tensile force.

[0019] The mechanism of the present disclosure will be explained using FIG. 2. FIG. 2(a) is a schematic side view of an electrode sheet and a pair of elastic rolls viewed from the width direction of the metal foil. FIG. 2(b) is a schematic front view of FIG. 2(a) viewed from the first direction of the metal foil, and FIG. 2(c) is an enlarged view of the dotted line portion of FIG. 2(b). FIG. 2(d) is a schematic front view illustrating a case where the elastic roll runs onto the coated portion. In the present disclosure, as shown in FIGS. 2(a) and 2(b), a pair of elastic rolls 20A and 20B are used to perform roll pressing on the uncoated portion 3 while applying a compressive force in the thickness direction. During this process, as shown in FIG. 2(c), the shape of elastic roll A may be transferred to elastic roll B due to the compressive force, resulting in distortion of elastic roll B. Furthermore, due to the nature of roll pressing, a compressive force is applied to the distorted portion again before the distortion is completely resolved, so the distortion remains during roll pressing. In other words, permanent distortion occurs in elastic roll B. This type of distortion is particularly pronounced when elastic roll A is a stepped roll and elastic roll B is a cylindrical roll (non-stepped roll). If the elastic rolls run onto the coating area due to meandering or other reasons while this distortion is occurring, a difference in the distance (clearance) between elastic rolls A and B may occur, as shown in Figure 2(d). In this case, shear stress concentrates in the area with small clearance, which can cause streaks or breakage in the coating area. This can result in a deterioration in the quality of the resulting electrode. In particular, the greater the distortion (depression) in elastic roll B, the more pronounced the shear stress concentration becomes.

[0020] In contrast, in the present disclosure, the Young's modulus X of the elastic body in elastic roll A is lower than the Young's modulus Y of the elastic body in elastic roll B. Therefore, strain on elastic roll B due to compressive force is reduced or no strain occurs. As a result, even if the elastic roll runs over the coating section, the occurrence of streaks in the coating section and breakage of the electrode sheet can be suppressed, and deterioration in the quality of the obtained electrode can be suppressed. Furthermore, in the present disclosure, since strain occurring in elastic roll B can be suppressed, the durability of the elastic rolls, particularly elastic roll B, can be improved.

[0021] 1. Preparation process The preparation step in the present disclosure is a step of preparing a precursor sheet having a metal foil with a longitudinal direction in a first direction and a coated portion and an uncoated portion disposed on the metal foil.

[0022] 3 is a schematic plan view illustrating a precursor sheet prepared in the preparation step. As shown in FIG. 3, precursor sheet 10 has metal foil 1 having a longitudinal direction in first direction D, coated portion 2, and uncoated portion 3.

[0023] Examples of materials for the metal foil include metals used as materials for battery current collectors. Details are described in "4. Electrodes." The thickness of the metal foil is, for example, 1 μm or more, and may be 10 μm or more. On the other hand, the thickness of the metal foil is, for example, 100 μm or less.

[0024] The coated portion of the precursor sheet contains an electrode material including at least an active material. The coated portion is disposed on a metal foil. The coated portion becomes an electrode layer through a coated portion pressing process described below.

[0025] The electrode material contains at least an active material. The electrode material may also contain at least one of a solid electrolyte, a conductive material, and a binder, as needed. The active material, conductive material, and binder are described in "4. Electrodes."

[0026] The coated portion may be disposed only on the first surface of the metal foil in the thickness direction, or may be disposed on both the first surface and the second surface opposite to the first surface.

[0027] The coated portions are preferably arranged along the first direction of the metal foil. Alternatively, the coated portions may be arranged continuously along the first direction D of the metal foil 1, as shown in Figure 3. Alternatively, the coated portions 1 may be arranged intermittently along the first direction D of the metal foil 1.

[0028] The thickness of the coated portion is not particularly limited and can be adjusted appropriately depending on the desired electrode size. The thickness of the coated portion is, for example, 0.2 mm or more, or may be 0.3 mm or more, or 0.5 mm or more. On the other hand, the thickness of the coated portion is, for example, 1.5 mm or less, or may be 1.0 mm or less, or may be 0.6 mm or less.

[0029] The width of the coated portion (the length in the direction perpendicular to the first direction of the metal foil) is not particularly limited and can be adjusted appropriately depending on the desired electrode size. The ratio of the width of the coated portion to the width of the metal foil is, for example, 30% or more, or may be 50% or more, or may be 70% or more. Furthermore, this ratio may be, for example, 90% or less, or may be 80% or less.

[0030] The uncoated portion is disposed on the metal foil. The uncoated portion is typically disposed on the same surface of the metal foil as the coated portion. The uncoated portion is, for example, an exposed portion of the metal foil. As shown in FIG. 3, the uncoated portion 3 in the present disclosure is disposed at the end of the coated portion 2 in a direction perpendicular to the first direction D of the metal foil 1. Although not shown, the uncoated portion may have a protective layer containing a resin at the boundary with the coated portion.

[0031] The width of the uncoated portion (the length in the direction perpendicular to the first direction of the metal foil) is not particularly limited and can be adjusted appropriately depending on the desired electrode size. The ratio of the width of the uncoated portion to the width of the metal foil is, for example, 3% or more, and may be 5% or more. On the other hand, this ratio is, for example, 20% or less, and may be 10% or less.

[0032] The precursor sheet can be prepared, for example, by applying an electrode material containing a dispersion medium to a metal foil and drying the applied material. Examples of the dispersion medium include organic solvents such as butyl butyrate, dibutyl ether, and heptane. The method for applying the electrode material is not particularly limited, and a general application method can be used. The drying temperature is not particularly limited as long as it is a temperature at which the dispersion medium volatilizes.

[0033] The precursor sheet prepared in the preparation step may be, for example, a precursor sheet 10 having, in a plan view, one row of coated sections 2 and two rows of uncoated sections 3 arranged in a striped pattern, as shown in Fig. 3. Alternatively, although not shown, the precursor sheet may have, in a plan view, N rows (N is an integer of 2 or greater) of coated sections and uncoated sections arranged at both ends of each of the N rows of coated sections. In this case, the number of rows of uncoated sections is N+1.

[0034] 2. Coating press process The coated portion pressing step is a step of pressing the coated portion in the thickness direction while transporting the precursor sheet in the first direction. The coated portion pressing step may be performed before or after the uncoated portion pressing step described below.

[0035] The method and conditions for the coated portion pressing step are not particularly limited as long as the coated portion can be pressed and stretched. Examples of pressing methods include a roll pressing method in which the coated portion is roll-pressed. For example, the coated portion can be pressed by passing the precursor sheet between a pair of press rolls and pressing the press rolls against both sides of the precursor sheet in the thickness direction.

[0036] The compressive force in the coated portion pressing step is not particularly limited, but is preferably greater than the compressive force in the uncoated portion pressing step described below. This is because the coated portion of the precursor sheet may become wrinkled by wetting with the electrode material (slurry) containing a dispersion medium, and a large stretching force is required to smooth out these wrinkles.

[0037] 3. Pressing process for uncoated parts The uncoated portion pressing step is a step of pressing the uncoated portion in the thickness direction while conveying the precursor sheet in the first direction, before or after the coated portion pressing step. In the uncoated portion pressing step, a pair of elastic rolls, each having a shaft and an elastic body covering the shaft, is used to roll-press the uncoated portion in the thickness direction. In the present disclosure, a predetermined elastic roll A and a predetermined elastic roll B are used as the pair of elastic rolls.

[0038] By pressing the uncoated portion, the uncoated portion can be stretched, thereby adjusting the difference in elongation from the coated portion. The amount of elongation of the uncoated portion can be adjusted by changing the deformation force caused by the deformation of the elastic body. In this disclosure, a pair of elastic rolls with different deformation forces (elastic moduli) of the elastic body are used. Therefore, the amount of elongation of the uncoated portion depends on the elastic roll with the smaller deformation force of the elastic body, and the amount of elongation can be adjusted by changing the elastic body of elastic roll A with the smaller elastic modulus.

[0039] The uncoated portion pressing step will now be described with reference to the drawings. Fig. 4(a) is a schematic side view of the uncoated portion pressing step as seen from the width direction of the metal foil. Fig. 4(b) is a schematic front view of Fig. 4(a) as seen from the first direction D of the precursor sheet. Figs. 4(c) and 4(d) are views of the precursor sheet and elastic roll as seen from the thickness direction (Fig. 4(b) as seen from the top and bottom of the paper).

[0040] As shown in Figures 4(a) and (b), in the uncoated portion pressing step, the precursor sheet 10 is conveyed in a first direction D while passing between a predetermined pair of elastic rolls 20A and 20B, and a compressive force is applied to press the elastic rolls 20A and 20B against both sides of the precursor sheet in the thickness direction, thereby roll-pressing the uncoated portion 3 (metal foil 1). The elastic roll 20 typically has a roll shape in which an elastic body 22 is disposed around a shaft 21. Furthermore, as shown in Figure 4(b) and other figures, the shaft typically protrudes from the elastic body toward the outside of the elastic roll in the axial direction of the shaft.

[0041] The material of the shaft is not particularly limited, but is preferably a material having a larger Young's modulus than the elastic body, and examples of the material of the shaft include metal.

[0042] In the present disclosure, the Young's modulus X of the elastic body of elastic roll A is smaller than the Young's modulus Y of the elastic body of elastic roll B. The ratio of Young's modulus X to Young's modulus Y (X / Y) is, for example, 0.1 or more, or may be 0.3 or more, or may be 0.5 or more. On the other hand, the ratio of Young's modulus X to Young's modulus Y (X / Y) is, for example, 0.9 or less, or may be 0.8 or less, or may be 0.7 or less, or may be 0.6 or less.

[0043] The Young's modulus X and the Young's modulus Y are, for example, 11.1 MPa or more and 86.1 MPa or less, respectively. If the Young's modulus is too low, the deformation amount of the elastic body may become too large, and excessive deformation force may be applied to the uncoated portion. As a result, breakage may not be sufficiently suppressed. On the other hand, if the Young's modulus is too high, the deformation amount of the elastic body may become too small, and sufficient deformation force may not be applied to the uncoated portion.

[0044] The material of the elastic body is not particularly limited as long as it satisfies the relationship between the Young's modulus X and the Young's modulus Y, and examples thereof include rubber and resins such as urethane.

[0045] In the present disclosure, as shown in FIG. 4(b), in the axial direction L of the shaft 21, the length L1 of the elastic body 22 of the elastic roll A (20A) is preferably shorter than the length L2 of the elastic body 22 of the elastic roll B (20B). The ratio of L1 to L2 (L1 / L2) is, for example, 0.1 or more and 0.5 or less. Note that the elastic roll A in FIG. 4(b) has two elastic bodies 22 per shaft 21. L1 is the length per elastic body 22. In the present disclosure, the axial direction of the shaft of the elastic roll A and the axial direction of the shaft of the elastic roll B are parallel to each other.

[0046] As shown in FIG. 4(b), the shape of the elastic rolls may be such that one of the pair of elastic rolls (elastic roll A) is a stepped roll, and the other elastic roll (elastic roll B) is a non-stepped roll (a roll in which the entire axial direction of the shaft is covered with an elastic body: a cylindrical roll). For example, when elastic roll B is a cylindrical roll, deflection of the precursor sheet can be suppressed, and the occurrence of wrinkles can be suppressed. On the other hand, both elastic roll A and elastic roll B may be stepped rolls. Even in this case, it is preferable that elastic rolls A and B satisfy the above-mentioned L1 / L2 relationship.

[0047] Furthermore, in the uncoated portion pressing process, when observed from the thickness direction, as shown in Figures 4(b) and (c), the elastic body 22 of the elastic roll A (20A) has a first end E1 and a second end E2 positioned outside the first end in the axial direction L of the shaft body 21, and when observed from the thickness direction, it is preferable that the position of the first end E1 overlaps with the position of the elastic body 22 of the elastic roll B (20B).

[0048] 4(b) and 4(c), when observed from the thickness direction, the elastic roll A (20A) is preferably arranged so that the elastic body 22 contacts the precursor sheet 10 at a position overlapping the uncoated section 3, and so that the elastic roll A (20A) does not contact the precursor sheet 10 at a position overlapping the coated section 2. In this case, as shown in FIGS. 4(b) and 4(c), the elastic roll A (20A) has a first contact section C1 where the elastic body 22 is arranged at a position overlapping the uncoated section 3, and a non-contact section N1 that does not contact the precursor sheet (coated section 2 in FIG. 4(b)) at a position overlapping the coated section 2. Note that when a coated section is arranged on only one side of the metal foil, the non-contact section N1 may be a portion of the precursor sheet that does not contact the metal foil during roll pressing. The non-contact section N1 is typically a portion where no elastic body is arranged. The elastic body in the first contact portion C1 comes into contact with the uncoated portion 3 during the uncoated portion pressing process. On the other hand, the non-contact portion N1 does not usually come into contact with the precursor sheet during the uncoated portion pressing process. Also, as shown in Figures 4(b) and (c), the elastic roll A (20A) has first contact portions C1 at both ends of the non-contact portion N1.

[0049] 4(b) and 4(d), elastic roll B (20B) is preferably arranged so that, when observed from the thickness direction, the elastic body 22 is in contact with the precursor sheet 10 at a position overlapping the uncoated section 3, and so that the elastic body 22 is in contact with the precursor sheet 10 at a position overlapping the coated section 2. In this case, as shown in FIGS. 4(b) and 4(d), elastic roll B (20B) has, when observed from the thickness direction, a second contact section C2 in which the elastic body 22 is arranged at a position overlapping the uncoated section 3, and a third contact section C3 that is in contact with the precursor sheet (coated section 2 in FIG. 4(b)) at a position overlapping the coated section 2. The elastic body at the second contact section C2 comes into contact with the uncoated section 3 during the uncoated section pressing process. Meanwhile, the third contact section C3 comes into contact with the coated section during the uncoated section pressing process.

[0050] Preferably, elastic roll A is an elastic roll that applies a compressive force from above the precursor sheet, and elastic roll B is an elastic roll that applies a compressive force from below the precursor sheet.

[0051] 4. Electrode In the electrode manufactured by the method of the present disclosure, an electrode layer is formed on at least one surface of the metal foil. The electrode layer is a layer obtained by pressing the coated portion. The electrode manufactured by the method of the present disclosure may be a positive electrode or a negative electrode. In other words, the electrode layer may be a positive electrode layer or a negative electrode layer.

[0052] The metal foil typically functions as a current collector (current collector). That is, the metal foil may be a positive electrode current collector or a negative electrode current collector. When the metal foil is a positive electrode current collector, examples of the material for the metal foil include Al, SUS, and Ni. When the metal foil is a negative electrode current collector, examples of the material for the metal foil include Cu, SUS, and Ni.

[0053] The electrode layer contains at least an active material. When the electrode layer is a positive electrode layer, the active material is a positive electrode active material. Typical examples of the positive electrode active material include oxide active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., rock salt layered active materials, LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4, and olivine type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4.

[0054] When the electrode layer is a negative electrode layer, the active material is a negative electrode active material. Examples of the negative electrode active material include carbon active materials, oxide active materials, and metal active materials. Examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Examples of the oxide active material include Nb2O5, Li4Ti5O 12 and SiO. Examples of metal active materials include In, Al, Si, and Sn.

[0055] Furthermore, the electrode layer may contain at least one of a conductive material and a binder, if necessary.

[0056] Examples of conductive materials include carbon materials, metal particles, and conductive polymers. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB); and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF). Examples of binders include fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic binders.

[0057] Examples of applications of the electrodes in the present disclosure include Li-ion batteries. The battery in the present disclosure may also be a liquid-based battery in which the electrolyte layer contains a liquid electrolyte (electrolytic solution). Applications of the battery in the present disclosure are not particularly limited, and examples include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. It is particularly preferred that the battery be used as a driving power source for hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles. The battery in the present disclosure may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0058] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0059] [Experimental Example 1] Rubber (elastic body) with a specified Young's modulus was prepared. Using an autograph device, a jig was repeatedly pressed against the rubber and returned to its original position, and the stress generated during this process was measured. The results are shown in Figure 5.

[0060] As shown in Figure 5, it was confirmed that the first load caused permanent strain in the rubber, and that from the second load onwards, due to the influence of the strain that had occurred, no stress was generated until the jig moved by the magnitude (depth) of the strain. In this way, it was confirmed that when an elastic body is used in roll pressing, permanent strain is generated in the elastic body.

[0061] [Experimental Example 2] Using CAE analysis, we simulated the shear stress applied to the electrode sheet when there was no difference in Young's modulus between the elastic rolls and when there was a difference in Young's modulus. Figure 6(a) shows the results when there was no difference in Young's modulus, and Figure 6(b) shows the results when there was a difference in Young's modulus.

[0062] As shown in Figure 6(a), when the Young's moduli were equal, the maximum shear stress applied to the coated area was 4.13 on the bottom surface of the electrode sheet. On the other hand, as shown in Figure 6(b), when the Young's modulus on the upper side was lowered, the maximum shear stress applied to the coated area decreased to 3.65 on the top surface of the electrode sheet, and the shear stress on the bottom surface also decreased to 3.43. Thus, it was confirmed that using elastic bodies with different Young's moduli reduces the shear stress applied to the coated area, thereby suppressing breakage and streaking when the material rides up on the coated area. [Explanation of symbols]

[0063] 1...metal foil 2... Coating department 3...Uncoated area 10...precursor sheet 21... Shaft 22...Elastic body 20...Elastic roll 20A...Elastic Roll A 20B...Elastic roll B

Claims

1. a preparation step of preparing a precursor sheet having a metal foil with a longitudinal direction in a first direction and a coated portion and an uncoated portion disposed on the metal foil; a coated portion pressing step of pressing the coated portion in a thickness direction while conveying the precursor sheet in the first direction; an uncoated portion pressing step of pressing the uncoated portion in the thickness direction while conveying the precursor sheet in the first direction, before or after the coated portion pressing step; and the coated portion contains an electrode material including at least an active material, the uncoated portion does not contain the electrode material and is arranged at an end of the coated portion in a direction perpendicular to the first direction, In the uncoated portion pressing step, a pair of elastic rolls having a shaft and a resin elastic body covering the shaft are used to perform roll pressing while applying a compressive force that presses the uncoated portion in the thickness direction, The pair of elastic rolls is made of elastic roll A and elastic roll B, the Young's modulus X of the elastic body in the elastic roll A is lower than the Young's modulus Y of the elastic body in the elastic roll B, a ratio (X / Y) of the Young's modulus X to the Young's modulus Y is 0.1 or more and 0.9 or less; The method for manufacturing an electrode, wherein Young's modulus X and Young's modulus Y are 11.1 MPa or more and 86.1 MPa or less, respectively.

2. The method for manufacturing an electrode according to claim 1 , wherein the length of the elastic body of the elastic roll A is shorter than the length of the elastic body of the elastic roll B in the axial direction of the shaft body.

3. When observed from the thickness direction, the elastic body of the elastic roll A has, in the axial direction of the shaft, a first end and a second end disposed outward from the first end, The method for manufacturing an electrode according to claim 1 or 2, wherein the position of the first end overlaps the position of the elastic body of the elastic roll B when observed from the thickness direction.

4. the elastic roll A is disposed such that, when observed from the thickness direction, the elastic body is in contact with the precursor sheet at a position overlapping the uncoated portion, and the elastic roll A is disposed such that it does not come into contact with the precursor sheet at a position overlapping the coated portion, 3. The method for manufacturing an electrode according to claim 1, wherein, when observed from the thickness direction, the elastic roll B is arranged so that the elastic body is in contact with the precursor sheet at a position overlapping the uncoated portion, and is also arranged so that the elastic body is in contact with the precursor sheet at a position overlapping the coated portion.

Images