Method for manufacturing an electrode

Abstract

To provide a manufacturing method of an electrode, capable of suppressing deterioration in quality.SOLUTION: A manufacturing method of an electrode includes: a preparation step of preparing a precursor sheet having a coating part 2 and an uncoating part that are arranged on a metal foil 1; a coating part press step; and an uncoating part press step. In the uncoating part press step, a roll pressing is performed by using a pair of elastic rolls A, B, the elastic roll having an elastic body 22 covering a shaft body 21. When viewed in a cross section along an axis of rotation of the elastic roll A (20A), the elastic body of the elastic roll A has a first side S1, a second side S2 facing the first side, a third side S3 extending in a direction crossing the first side and the second side, a fourth side S4 facing the third side, a first connecting part SL1 connecting the first side and the third side, and a second connecting part SL2 connecting the second side and the third side. The elastic roll A is arranged such that the third side is located closer on a coating part side than the fourth side.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] As a method for manufacturing an electrode, a method of rolling a sheet obtained by applying an electrode composite material on a long metal foil is known.

[0003] For example, Patent Document 1 discloses a pressing method for an electrode for a battery having a coated portion coated with an electrode active material and an uncoated portion not coated with the electrode active material. Further, Patent Document 2 discloses a roll pressing method using a roll press machine provided with a wrinkle prevention device for suppressing the generation of wrinkles generated by a roll pressing operation between a coated portion and an uncoated portion of an electrode plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, when pressing a sheet having a coated portion and an uncoated portion, the coated portion and the uncoated portion may be pressed individually to adjust the elongation difference so that wrinkles do not occur. In addition, when pressing the uncoated portion, the uncoated portion may be roll-pressed using an elastic roll so that the uncoated portion does not break.

[0006] The inventors of the present invention have found that when pressing the uncoated portion using an elastic roll, if the elastic roll rides on the coated portion due to meandering or the like, streaks may occur in the coated portion or the coated portion may break, and the quality of the obtained electrode may deteriorate.

[0007] The present disclosure has been made in view of the above circumstances, and the main object thereof is to provide a method for manufacturing an electrode capable of suppressing deterioration of quality.

Means for Solving the Problems

[0008] [1] 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 disposed on the metal foil; while conveying the precursor sheet in the first direction, pressing the coated portion in a thickness direction, a coated portion pressing step; before or after the coated portion pressing step, while conveying the precursor sheet in the first direction, pressing the uncoated portion in the thickness direction, an uncoated portion pressing step, wherein the coated portion contains an electrode material containing 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 second direction orthogonal to the first direction, and in the uncoated portion pressing step, while applying a compressive force for pressing the uncoated portion in the thickness direction using a pair of elastic rolls having a shaft body and an elastic body covering the shaft body, performing roll pressing, using elastic roll A and elastic roll B as the pair of elastic rolls, when the elastic body of the elastic roll A is viewed in cross section along the rotation axis of the elastic roll A, it has a first side, a second side facing the first side, a third side extending in a direction intersecting the first side and the second side, a fourth side facing the third side, a first connecting portion connecting the first side and the third side, and a second connecting portion connecting the second side and the third side, when the boundary between the first side and the first connecting portion is P1 and the boundary between the third side and the first connecting portion is P2, the first connecting portion is a single straight line connecting P1 and P2, when the boundary between the second side and the second connecting portion is Q1 and the boundary between the third side and the second connecting portion is Q2, the second connecting portion is a single straight line connecting Q1 and Q2, and arranging the elastic roll A so that the third side is located closer to the coated portion side than the fourth side during the roll pressing, a method for manufacturing an electrode.

[0009] [2] The manufacturing method of the electrode according to [1], wherein in the axial direction of the rotation axis, 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.

[0010] [3] When observed from the thickness direction, the elastic body of the elastic roll A has a first end portion and a second end portion disposed outside the first end portion in the axial direction of the rotation axis. When observed from the thickness direction, the position of the first end portion overlaps with the position of the elastic body of the elastic roll B. The manufacturing method of the electrode according to [1] or [2].

[0011] [4] When observed from the thickness direction, the elastic roll A is arranged such that the elastic body contacts the precursor sheet at a position overlapping the uncoated portion, and the elastic roll A is arranged such that it does not contact the precursor sheet at a position overlapping the coating portion. The elastic roll B is arranged such that the elastic body contacts the precursor sheet at a position overlapping the uncoated portion when observed from the thickness direction, and the elastic body is arranged such that it contacts the precursor sheet at a position overlapping the coating portion. The manufacturing method of the electrode according to any one of [1] to [3]. [Advantages of the Invention]

[0012] In the present disclosure, there is an effect of providing a manufacturing method of an electrode capable of suppressing deterioration in quality. [Brief Description of the Drawings]

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the method for manufacturing an electrode in the present disclosure will be described in detail. Here, in this specification, when expressing the mode of arranging one member with respect to another member, when simply described as "above", unless otherwise specified, it includes both the case of arranging another member directly above so as to be in contact with one member and the case of arranging another member above one member via another member.

[0015] FIG. 1 is a flowchart showing an example of the method for manufacturing an electrode in the present disclosure. In FIG. 1, first, a precursor sheet having a metal foil having a longitudinal direction in a first direction and a coated part and an uncoated part disposed on the metal foil is prepared (preparation step). The coated part contains an electrode material containing at least an active material. Further, the uncoated part does not contain the electrode material and is disposed at an end of the coated part in a second direction orthogonal to the first direction. Next, while transporting the precursor sheet in the first direction, the coated part is pressed in the thickness direction (coated part press step). Then, while transporting the precursor sheet in the first direction, the uncoated part is pressed in the thickness direction (uncoated part press step). In FIG. 1, the uncoated part press step is performed after the coated part press step, but it may also be performed before the coated part press step. Also, in the uncoated part press step, roll pressing is performed using a predetermined pair of elastic rolls. Particularly in the present disclosure, when viewed in cross section along the axial direction of the rotation axis, the elastic roll A has a predetermined shape. Here, in the present disclosure, the "thickness direction" is synonymous with the lamination direction of the metal foil and the coated part. Also, in the present disclosure, the "axial direction of the rotation axis" may be referred to as the "axial direction" or the "axial direction of the shaft body".

[0016] According to the present disclosure, when viewed in cross-section along the rotation axis, since the elastic roll A has a predetermined first connecting portion and a second connecting portion, even when the elastic roll rides on the coating section due to meandering or the like, breakage or the like can be suppressed, and deterioration in the quality of the resulting electrode can be suppressed.

[0017] As a method for manufacturing an electrode, a method of pressing a precursor sheet in which an electrode composite material is coated on a metal foil (current collecting foil) is known. Further, due to the presence or absence of the electrode composite material, a difference in elongation rate occurs after pressing between the coated portion and the uncoated portion of the metal foil, and there is a risk of wrinkles occurring in the electrode. In this regard, as in Patent Document 1 described above, the coated portion and the uncoated portion are pressed individually to suppress the occurrence of wrinkles. Further, in the pressing of the uncoated portion (metal foil), a pair of elastic rolls may be used to perform roll pressing while applying a compressive force for pressing in the thickness direction. By performing such roll pressing, it is possible to apply, to the uncoated portion, a deformation force caused by the deformation of the elastic body together with the above-described compressive force. Thereby, for example, breakage of the uncoated portion can be effectively prevented.

[0018] Here, generally, a hard tissue harder than the material of the metal foil is included as an inclusion in the metal foil. By including the hard tissue, for example, the strength of the metal foil can be increased. When a tensile force (horizontal force) for stretching the metal foil is applied, although the hard tissue does not deform, the surrounding metal foil that is softer than the hard tissue deforms. As a result, voids are formed around the hard tissue. And when a plurality of voids are connected to each other, breakage is likely to occur. On the other hand, in the present disclosure, a pair of elastic rolls are used to perform roll pressing while applying a compressive force for pressing in the thickness direction. Thereby, it is considered that the generation of voids around the hard tissue can be suppressed. The above-described compressive force corresponds to a force in the thickness direction, and the above-described deformation force corresponds to a force in a direction orthogonal to the thickness direction. That is, the above-described deformation force acts in the same direction as the tensile force, and is a force that stretches the metal foil in the same manner as the tensile force.

[0019] The mechanism in the present disclosure will be described with reference to FIG. 2. FIG. 2(a) is a schematic side view of the electrode sheet and a pair of elastic rolls as viewed from the second direction of the metal foil. FIG. 2(b) is a schematic front view of FIG. 2(a) as 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). Also, FIGS. 2(d) and (e) are schematic front views illustrating the case where the elastic roll rides on the coating section. In the present disclosure, as shown in FIGS. 2(a) and (b), a compressive force is applied in the thickness direction to the uncoated section 3 using a pair of elastic rolls 20A and 20B, and roll pressing is performed. At this time, as shown in FIG. 2(c), due to the compressive force, the shape of the elastic roll A may be transferred to the elastic roll B, and the elastic roll B may be deformed. Also, due to the nature of roll pressing, before the strain is completely eliminated, a compressive force is applied again to the strained portion, so the strain remains during roll pressing. In other words, permanent strain occurs in the elastic roll B. In particular, such strain becomes more prominent when the elastic roll A is a stepped roll and the elastic roll B is a cylindrical roll (non-stepped roll). If such a deformed elastic roll rides on the coating section due to meandering or the like in this deformed state, as shown in FIG. 2(d), a difference may occur in the distance (clearance) between the elastic roll A and the elastic roll B. In that case, shear stress may concentrate in the portion with a small clearance, and streaks may occur in the coating section or the coating section may break. As a result, the quality of the obtained electrode may deteriorate.

[0020] Regarding this point, the inventors of the present invention focused on the shape of the elastic roll, and as shown in Fig. 2(c), in the elastic body of the elastic roll A, when the connecting portion connecting side to side has a curved structure (so-called R chamfered structure), it was found that shear stress concentrates. And as will be described with reference to Fig. 4 below, if the connecting portion has a predetermined structure (so-called C chamfered structure), as shown in Fig. 2(e), even when the elastic roll rides onto the coating section in a state where permanent strain has occurred, it was found that the distance between the elastic roll A and the elastic roll B becomes uniform, and it was found that the concentration of shear stress is alleviated. This is because the shape of the permanent strain generated in the elastic roll B can be made the shape corresponding to the C chamfered structure of the elastic roll A.

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

[0022] Fig. 3 is a schematic plan view illustrating the precursor sheet prepared in the preparation process. As shown in Fig. 3, the precursor sheet 10 has a metal foil 1 having a longitudinal direction in a first direction D, a coating section 2, and an uncoated section 3.

[0023] Examples of the material of the metal foil include metals used as materials for current collectors of batteries. 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 coating section of the precursor sheet contains at least an electrode material containing an active material. Also, the coating section is disposed on the metal foil. The coating section becomes an electrode layer through a coating section pressing process described later.

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

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

[0027] The coating part is preferably arranged along the first direction of the metal foil. Also, as shown in FIG. 3, the coating part may be continuously arranged along the first direction D of the metal foil 1. On the other hand, the coating part 1 may be intermittently arranged along the first direction D of the metal foil 1.

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

[0029] The width of the coating part (the length in the second direction orthogonal to the first direction of the metal foil) is not particularly limited and can be appropriately adjusted according to the desired electrode size. The ratio of the width of the coating part to the width of the metal foil is, for example, 30% or more, may be 50% or more, and may be 70% or more. Also, the above ratio is, for example, 90% or less, and may be 80% or less.

[0030] The uncoated part is arranged on the metal foil. Also, the uncoated part is usually arranged on the same surface as the surface of the metal foil where the coating part is arranged. The uncoated part is, for example, a part where the metal foil is exposed. As shown in FIG. 3, the uncoated part 3 in the present disclosure is arranged at the end of the coating part 2 in the second direction orthogonal to the first direction D of the metal foil 1. Also, although not shown, a protective layer containing resin may be provided at the boundary part with the coating part in the uncoated part.

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

[0032] The precursor sheet can be prepared, for example, by coating an electrode material containing a dispersion medium on a metal foil and drying it. Examples of the dispersion medium include organic solvents such as butyl butyrate, dibutyl ether, and heptane. The coating method of the electrode material is not particularly limited, and common coating methods can be mentioned. Also, 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 process may be, for example, a precursor sheet 10 having, in plan view, a single row of coated parts 2 and two rows of uncoated parts 3 arranged at both ends of the coated parts 2 in a stripe shape as shown in FIG. 3. Also, although not shown, the precursor sheet may be a sheet having, in plan view, N rows (N is an integer of 2 or more) of coated parts and uncoated parts arranged at both ends of each of the N rows of coated parts. In this case, the number of rows of the uncoated parts is N + 1 rows.

[0034] 2. Coated Part Pressing Process The coated part pressing process is a process of pressing the coated part in the thickness direction while conveying the precursor sheet in the first direction. The coated part pressing process may be performed before or after the uncoated part pressing process described later.

[0035] The method and conditions of the coated part pressing process are not particularly limited as long as the coated part can be pressed and stretched. Examples of the pressing method include a roll pressing method of roll-pressing the coated part. For example, while passing the precursor sheet between a pair of pressing rolls, the coated part can be pressed by pressing the pressing rolls against both surfaces of the precursor sheet in the thickness direction.

[0036] The compression force in the coating part pressing process is not particularly limited, but it is preferably greater than the compression force in the uncoated part pressing process described later. In the coating part of the precursor sheet, wrinkles may occur due to wetting with the electrode material (slurry) containing the dispersion medium. This is because a large stretching force is required to stretch these wrinkles.

[0037] 3. Uncoated Part Pressing Process The uncoated part pressing process is a process of pressing the uncoated part in the thickness direction while transporting the precursor sheet in the first direction before or after the above coating part pressing process. In the uncoated part pressing process, a pair of elastic rolls having a shaft body and an elastic body covering the shaft body are used to perform roll pressing while pressing the uncoated part in the thickness direction. In the present disclosure, a predetermined elastic roll A and elastic roll B are used as the pair of elastic rolls.

[0038] By pressing the uncoated part, the uncoated part can be stretched to adjust the elongation difference from the coating part. The elongation amount of the uncoated part can be adjusted by changing the deformation force caused by the deformation of the elastic body.

[0039] First, the elastic roll A used in the uncoated part pressing process will be described with reference to FIG. 4. FIG. 4(a) is a schematic cross-sectional view of the elastic roll A viewed in cross-section along the rotation axis. FIG. 4(b) is an external perspective view of the elastic roll A shown in FIG. 4(a). FIG. 4(c) is a schematic cross-sectional view for explaining the arrangement of the elastic roll A in the uncoated part pressing process.

[0040] As shown in Fig. 4(a), the elastic roll A has a shaft body 21 and an elastic body 22. When the elastic roll A (20A) is viewed in cross-section along the rotation axis (X direction), the elastic body 22 of the elastic roll A (20A) has a first side S1, a second side S2 facing the first side S1, a third side S3 extending from the outer edge of the first side S1 toward the second side S2, and a fourth side S4 facing the third side S3. The elastic body 22 also has a first connecting portion SL1 connecting the first side S1 and the third side S3, and a second connecting portion SL2 connecting the second side S2 and the third side S3. When the boundary between the first side S1 and the first connecting portion SL1 is defined as P1 and the boundary between the third side S3 and the first connecting portion SL1 is defined as P2, the second connecting portion SL1 is a straight line connecting P1 and P2. When the boundary between the second side S2 and the second connecting portion SL2 is defined as Q1 and the boundary between the third side S3 and the second connecting portion SL2 is defined as Q2, the second connecting portion SL2 is a straight line connecting Q1 and Q2. As shown in Fig. 4(a) etc., in the above-mentioned cross-sectional view, the third side S3 and the fourth side S4 usually have a portion including the shaft body 21. On the other hand, in the present disclosure, it is possible not to consider the shaft body portion for the third side and the fourth side.

[0041] Here, P2 is located more inward than P1 in the radial direction (Z direction) of the elastic roll A. That is, in the radial direction (Z direction), P1 protrudes more than P2. In other words, a structure (C chamfer structure) is formed in which the corner portion formed by the extension line of the first side S1 and the extension line of the third surface S3 is cut by the first connecting portion SL1. Similarly, Q2 is located more inward than Q1 in the radial direction (Z direction) of the elastic roll A, and a structure (C chamfer structure) is formed in which the corner portion formed by the extension line of the second side S2 and the extension line of the third surface S3 is cut by the second connecting portion SL2. The elastic body 22 of the elastic roll A (20A) may have a third connecting portion connecting the first side and the fourth side, and a fourth connecting portion connecting the second side and the fourth side. The third connecting portion and the fourth connecting portion are the same as the above-mentioned first connecting portion and second connecting portion.

[0042] Further, in the above cross-sectional view, the angles formed by the first side and the first connecting portion, and the angles formed by the second side and the second connecting portion are, for example, each 100 degrees or more and 170 degrees or less. Also, in the above cross-sectional view, the angles formed by the third side and the first connecting portion, and the angles formed by the third side and the second connecting portion are, for example, each 100 degrees or more and 170 degrees or less. Note that the above angles refer to the obtuse-side angles of the angles formed by the sides and the connecting portions in FIG. 4(a).

[0043] Also, as shown in FIG. 4(b), when observing the appearance of the elastic roll A, the elastic body 22 of the elastic roll A (20A) usually has the first tapered surface T1 composed of the above-described first connecting portion and second connecting portion. Further, as shown in FIG. 4(b), the elastic roll A is preferably a so-called stepped roll having the above-described elastic bodies at both ends of the shaft body in the axial direction X of the rotation axis. Although not shown, when the elastic body has the above-described third connecting portion and fourth connecting portion, it usually has a second tapered surface at a position facing the first tapered surface in the axial direction (X direction) of the rotation axis of the elastic roll A.

[0044] Also, as shown in FIG. 4(c), in the uncoated portion pressing process, the elastic roll A (20A) is arranged so that the third side S3 is located closer to the coating portion 2 side than the fourth side S4 during roll pressing. As shown in FIG. 4(c), the direction (X direction) of the rotation axis of the elastic roll A is parallel to the above-described first direction D, and the radial direction (Z direction) of the elastic roll A is parallel to the above-described thickness direction. Note that "parallel" includes not only strict parallelism but also cases where the angle formed by the two directions is 10° or less. The above angle may be 5° or less.

[0045] Next, the uncoated portion pressing process will be described with reference to FIG. 5. FIG. 5(a) is a schematic side view of the uncoated portion pressing process as viewed from the second direction and the axial direction of the metal foil. FIG. 5(b) is a schematic front view of FIG. 5(a) as viewed from the first direction D of the precursor sheet. FIGS. 5(c) and (d) are views of the precursor sheet and the elastic roll as observed from the thickness direction (a view of FIG. 5(b) as observed from the up-down direction of the paper surface).

[0046] As shown in FIGS. 5(a) and (b), in the uncoated part pressing process, while the precursor sheet 10 is being conveyed in the first direction D, the precursor sheet 10 is passed between a predetermined pair of elastic rolls 20A and 20B, and a compressive force for pressing the elastic rolls 20A and 20B against both surfaces in the thickness direction of the precursor sheet is applied, and the uncoated part 3 (metal foil 1) is roll-pressed. The elastic roll 20 usually has a roll shape in which an elastic body 22 is disposed around a shaft body 21.

[0047] The material of the shaft body is not particularly limited, but a material having a Young's modulus larger than that of the elastic body is preferable. Examples of the material of the shaft body include metals.

[0048] The elastic body preferably has a predetermined Young's modulus. The Young's modulus is 11.1 MPa or more and 86.1 MPa or less. If the Young's modulus is too low, the amount of deformation of the elastic body becomes too large, and there is a risk that an excessive deformation force is applied to the uncoated part. As a result, there is a risk that breakage cannot be sufficiently suppressed. On the other hand, if the Young's modulus is too high, the amount of deformation of the elastic body becomes too small, and there is a risk that a sufficient deformation force cannot be applied to the uncoated part.

[0049] The material of the elastic body is not particularly limited, and examples thereof include resins such as rubber and urethane.

[0050] In the present disclosure, as shown in FIG. 5(b), in the axial direction X of the shaft body 21, the length XL1 of the elastic body 22 of the elastic roll A (20A) is preferably shorter than the length XL2 of the elastic body 22 of the elastic roll B (20B). The ratio (XL1 / XL2) of XL1 to XL2 is, for example, 0.1 or more and 0.5 or less. Note that the elastic roll A in FIG. 5(b) has two elastic bodies 22 with respect to one shaft body 21. XL1 is the length per one elastic body 22. Also, in the present disclosure, the axial direction of the shaft body of the elastic roll A and the axial direction of the shaft body of the elastic roll B are parallel.

[0051] Further, as shown in Fig. 5(b), the shape of the elastic roll 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) may be a non-stepped roll (a roll in which the entire axial direction of the shaft body is covered with an elastic body: a cylindrical roll). In particular, as shown in Figs. 4(b) and 5(b) described above, it is preferable that the elastic roll A is a stepped roll. For example, when the elastic roll B is a cylindrical roll, the deflection generated in the precursor sheet can be suppressed, and the generation of wrinkles can be suppressed. On the other hand, both the elastic roll A and the elastic roll B may be stepped rolls. Even in this case, it is preferable that the elastic rolls A and B satisfy the above XL1 / XL2 relationship.

[0052] Also, in the uncoated part pressing process, when observed from the thickness direction, as shown in Figs. 5(b) and (c), the elastic body 22 of the elastic roll A (20A) has a first end E1 and a second end E2 arranged outside the first end E1 in the axial direction X of the rotation axis. 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). The first end is the part including the third side described above, and the second end is the part including the fourth side described above.

[0053] Further, as shown in FIGS. 5(b) and 5(c), the elastic roll A (20A) is arranged such that the elastic body 22 contacts the precursor sheet 10 at a position overlapping with the uncoated portion 3 when observed from the thickness direction, and the elastic roll A (20A) is arranged such that it does not contact the precursor sheet 10 at a position overlapping with the coating portion 2. In this case, as shown in FIGS. 5(b) and 5(c), the elastic roll A (20A) includes a first contact portion C1 where the elastic body 22 is arranged at a position overlapping with the uncoated portion 3, and a non-contact portion N1 that does not contact the precursor sheet (the coating portion 2 in FIG. 5(b)) at a position overlapping with the coating portion 2. When the coating portion is arranged only on one side of the metal foil, the non-contact portion N1 may be a portion of the precursor sheet that does not contact the metal foil during roll pressing. Also, the non-contact portion N1 is typically a portion where no elastic body is arranged. The elastic body in the first contact portion C1 contacts the uncoated portion 3 in the uncoated portion pressing process. On the other hand, the non-contact portion N1 usually does not contact the precursor sheet in the uncoated portion pressing process. Further, as shown in FIGS. 5(b) and 5(c), the elastic roll A (20A) includes first contact portions C1 at both ends of the non-contact portion N1 in the conveyance direction of the precursor sheet (the front-rear direction of the paper surface in FIG. 4(b)).

[0054] Further, as shown in FIGS. 5(b) and 5(d), the elastic roll B (20B) is arranged such that the elastic body 22 contacts the precursor sheet 10 at a position overlapping with the uncoated portion 3 when observed from the thickness direction, and the elastic body 22 is arranged such that it contacts the precursor sheet 10 at a position overlapping with the coating portion 2. In this case, as shown in FIGS. 5(b) and 5(d), the elastic roll B (20B) includes a second contact portion C2 where the elastic body 22 is arranged at a position overlapping with the uncoated portion 3 when observed from the thickness direction, and a third contact portion C3 that contacts the precursor sheet (the coating portion 2 in FIG. 5(b)) at a position overlapping with the coating portion 2. Also, the elastic body in the second contact portion C2 contacts the uncoated portion 3 in the uncoated portion pressing process. On the other hand, the third contact portion C3 contacts the coating portion in the uncoated portion pressing process.

[0055] Further, it is preferable that the elastic roll A is an elastic roll that applies a compressive force from above the precursor sheet, and the elastic roll B is an elastic roll that applies a compressive force from below the precursor sheet.

[0056] 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 coating portion described above. The electrode manufactured by the method of the present disclosure may be a positive electrode or a negative electrode. That is, the electrode layer may be a positive electrode layer or a negative electrode layer.

[0057] The metal foil typically functions as a current collector foil (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 of the metal foil include Al, SUS, and Ni. When the metal foil is a negative electrode current collector, examples of the material of the metal foil include Cu, SUS, and Ni.

[0058] 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 the oxide active material include rock salt layer type active materials such as LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and the like, spinel type active materials such as LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4 and the like, and olivine type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4.

[0059] 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 pyrolytic graphite (HOPG), hard carbon, and soft carbon. Examples of the oxide active material include Nb2O5, Li4Ti5O 12 and SiO. Examples of the metal active material include In, Al, Si, and Sn.

[0060] In addition, the electrode layer may contain at least one of a conductive material and a binder, if necessary.

[0061] Examples of the conductive material include carbon materials, metal particles, and conductive polymers. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB); fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF). Examples of the binder include fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic binders.

[0062] Examples of the use of the electrode in the present disclosure include Li-ion batteries. Further, the battery in the present disclosure may be a liquid-based battery in which the electrolyte layer contains a liquid-based electrolyte (electrolyte solution). The use of the battery in the present disclosure is not particularly limited, and examples include power sources for vehicles such as hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV), gasoline vehicles, and diesel vehicles. In particular, it is preferably used as a driving power source for a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a battery electric vehicle. Further, the battery in the present disclosure may be used as a power source for a moving body other than a vehicle (for example, a railway, a ship, an aircraft), or may be used as a power source for an electric product such as an information processing device.

[0063] Note that the present disclosure is not limited to the above embodiments. The above embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits the same operational effects is included in the technical scope of the present disclosure.

Example

[0064] [Experimental Example 1] Rubber (elastomer) having a predetermined Young's modulus was prepared. Using an autograph device, the jig was repeatedly pressed against the rubber and returned to its original position, and the stress generated at that time was measured. The results are shown in Fig. 6(a).

[0065] As shown in Fig. 6(a), it was confirmed that permanent strain occurred in the rubber with the first load, and due to the influence of the strain generated with subsequent loads, no stress occurred until the jig moved by the amount of the strain (depth). Thus, it was confirmed that permanent strain occurs in the elastomer when roll pressing is performed using the elastomer.

[0066] [Experimental Example 2] By CAE analysis, the shear stress applied to the electrode sheet was simulated when the first connecting portion and the second connecting portion were not provided in the elastic roll A and when the first connecting portion and the second connecting portion were provided in the elastic roll A. The results when the first connecting portion and the second connecting portion were not provided are shown in Fig. 6(b), and the results when they were provided are shown in Fig. 6(c).

[0067] As shown in Figs. 6(b) and (c), when the predetermined first connecting portion and second connecting portion were provided, the maximum value of the shear stress applied to the coating portion decreased on both the upper and lower surfaces of the electrode sheet. Thus, it was confirmed that by using the elastic roll A having the predetermined first connecting portion and second connecting portion, the shear stress applied to the coating portion can be reduced, and breakage and streak generation when riding on the coating portion can be suppressed.

Explanation of Reference Numerals

[0068] 1 … Metal foil 2 … Coating section 3 … Uncoated section 10 … Precursor sheet 21 … Shaft body 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 transporting the precursor sheet in the first direction; An uncoated portion pressing step of pressing the uncoated portion in the thickness direction while transporting the precursor sheet in the first direction before or after the coated portion pressing step; comprising: 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 second direction orthogonal to the first direction; In the uncoated portion pressing step, while applying a compressive force to press the uncoated portion in the thickness direction using a pair of elastic rolls having a shaft body and an elastic body covering the shaft body, roll pressing is performed; As the pair of elastic rolls, elastic roll A and elastic roll B are used; The elastic roll A has an elastic body A as the elastic body; The elastic roll B has an elastic body B as the elastic body; The elastic body A of the elastic roll A: When viewed in cross-section along the rotation axis of the elastic roll A, it has a first side, a second side facing the first side, a third side extending in a direction intersecting the first side and the second side, a fourth side facing the third side, a first connecting portion connecting the first side and the third side, and a second connecting portion connecting the second side and the third side; Let the boundary between the first side and the first connecting part be P １ and let the boundary between the third side and the first connecting part be P ２ In this case, the first connecting part is a single straight line connecting １ and ２ ​ Let the boundary between the second side and the second connecting part be Q １ and let the boundary between the third side and the second connecting part be Q ２ In this case, the second connecting part is １ a single straight line connecting ２ the Q and the Q During the roll pressing: The elastic roll A is arranged such that the third side is located closer to the coated portion side than the fourth side; The elastic roll A is arranged such that, when viewed from the thickness direction, at a position overlapping the uncoated portion, the elastic body A contacts the precursor sheet, and at a position overlapping the coated portion, the elastic roll A has a portion that does not contact the precursor sheet; The elastic roll B is arranged such that, when viewed from the thickness direction, at a position overlapping the uncoated portion, the elastic body B contacts the precursor sheet, and at a position overlapping the coated portion, the elastic body B contacts the precursor sheet. A method for manufacturing an electrode.

2. The method for manufacturing an electrode according to claim 1, wherein the elastic roll B is a stepped roll including the elastic body B having no chamfered C surface, or a roll without steps.

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

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

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