JP7735965B2 - Electrode manufacturing method - Google Patents

Description

This disclosure relates to a method for manufacturing an electrode.

One known method for manufacturing electrodes is to roll a sheet in which an electrode mixture is applied to a long metal foil.

For example, Patent Document 1 discloses a method for pressing battery electrodes having a coated portion coated with an electrode active material and an uncoated portion not coated with the electrode active material. Furthermore, Patent Document 2 discloses a roll pressing method using a roll press machine equipped with a wrinkle prevention device that prevents wrinkles from forming in the coated and uncoated portions of the electrode plate during the roll pressing process.

Patent No. 5760366 Japanese Patent Application Laid-Open No. 2019-102172

As mentioned above, when pressing a sheet having coated and uncoated areas, the coated and uncoated areas may be pressed separately to adjust the difference in elongation to prevent wrinkles from forming. Furthermore, the uncoated areas may be roll-pressed using an elastic roll to prevent them from breaking when pressed.

The inventors have discovered that when an elastic roll is used to press an uncoated area, if the elastic roll runs over the coated area due to meandering or other reasons, this can cause streaks or breakage in the coated area, potentially degrading the quality of the resulting electrode.

This disclosure was made in light of the above situation, and its main purpose is to provide a method for manufacturing electrodes that can suppress quality degradation.

[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, wherein 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, and in the uncoated portion pressing step, a pair of elastic rolls having a shaft and an 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, and elastic roll A and elastic roll B are used as the pair of elastic rolls, and Young's modulus X of the elastic body in elastic roll A is lower than Young's modulus Y of the elastic body in elastic roll B.

[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.

[3]
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. [1] or [2].

[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.

The present disclosure provides an electrode manufacturing method that can suppress quality degradation.

FIG. 1 is a flow diagram illustrating a method for manufacturing an electrode according to the present disclosure. FIG. 1 is a diagram illustrating the mechanism in the present disclosure. FIG. 2 is a schematic plan view illustrating a precursor sheet according to the present disclosure. FIG. 2 is a diagram illustrating an uncoated portion pressing step in the present disclosure. FIG. 1 is a diagram showing the results of Experimental Example 1. FIG. 10 is a diagram showing the results of Experimental Example 2.

The electrode manufacturing method according to the present disclosure is described in detail below. In this specification, when describing the arrangement of another member relative to a certain member, the term "above" refers to both the arrangement of another member directly above the member so as to be in contact with the member, and the arrangement of another member above the member via another member, unless otherwise specified.

Figure 1 is a flow diagram showing an example of a method for manufacturing an electrode according to the present disclosure. In Figure 1, first, a precursor sheet is prepared, which includes a metal foil having a longitudinal direction in a first direction and a coated portion and an uncoated portion disposed on the metal foil (preparation process). 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 process). Then, while the precursor sheet is conveyed in the first direction, the uncoated portion is pressed in the thickness direction (uncoated portion pressing process). Note that while Figure 1 shows the uncoated portion pressing process being performed after the coated portion pressing process, it may also be performed before the coated portion pressing process. Furthermore, in the uncoated portion pressing process, 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 this disclosure, the "thickness direction" is synonymous with the stacking direction of the metal foil and coated portion.

According to the present disclosure, 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. Therefore, 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 resulting electrode can be suppressed.

One 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. In response to this issue, as in Patent Document 1 mentioned above, the coated and uncoated portions are pressed separately to prevent wrinkles. Furthermore, when pressing the uncoated portion (metal foil), a pair of elastic rolls may be used to apply a compressive force in the thickness direction while performing roll pressing. By performing roll pressing in this manner, the uncoated portion can be subjected to a deformation force resulting from deformation of the elastic body in addition to the compressive force. This can effectively prevent, for example, breakage of the uncoated portion.

Here, metal foil generally contains inclusions of hard tissue that is harder than the material of the metal foil. The inclusion of hard tissue 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 tissue does not deform, but the surrounding metal foil, which is softer than the hard tissue, deforms. As a result, voids are formed around the hard tissue. 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 deformation of the elastic body in addition to the compressive force. As a result, it is believed that the formation of voids around the hard tissue 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, like the tensile force, stretches the metal foil.

The mechanism of the present disclosure will be explained using Figure 2. Figure 2(a) is a schematic side view of the electrode sheet and a pair of elastic rolls viewed from the width direction of the metal foil. Figure 2(b) is a schematic front view of Figure 2(a) viewed from the first direction of the metal foil, and Figure 2(c) is an enlarged view of the dotted line portion of Figure 2(b). Figure 2(d) is a schematic front view illustrating a case where the elastic roll runs over the coated portion. In this disclosure, as shown in Figures 2(a) and 2(b), roll pressing is performed on the uncoated portion 3 using a pair of elastic rolls 20A and 20B while applying a compressive force in the thickness direction. As shown in Figure 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, compression 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 roll runs onto the coating area due to meandering or other reasons while this type of distortion is occurring, a difference in the distance (clearance) between elastic roll A and elastic roll B may occur, as shown in Figure 2(d). In this case, shear stress concentrates in areas 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.

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, the strain on elastic roll B due to compression force is reduced, or no strain occurs. As a result, even if the elastic roll rides up on 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 resulting electrode can be suppressed. Furthermore, in the present disclosure, because the strain occurring in elastic roll B can be suppressed, the durability of the elastic rolls, particularly elastic roll B, can be improved.

1. Preparation Step 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.

Figure 3 is a schematic plan view illustrating the precursor sheet prepared in the preparation process. As shown in Figure 3, the precursor sheet 10 has a metal foil 1 with its longitudinal direction aligned in the first direction D, a coated portion 2, and an uncoated portion 3.

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.

The coated portion of the precursor sheet contains an electrode material that includes at least an active material. The coated portion is placed on a metal foil. The coated portion becomes an electrode layer after passing through the coated portion pressing process described below.

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

The coated portion may be located only on the first surface of the metal foil in the thickness direction, or may be located on both the first surface and the second surface opposite the first surface.

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.

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.

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 70% or more. Furthermore, the ratio may be, for example, 90% or less, or 80% or less.

The uncoated portion is disposed on the metal foil. Furthermore, 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 Figure 3, the uncoated portion 3 in this 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. Furthermore, although not shown, a protective layer containing resin may be provided at the boundary between the uncoated portion and the coated portion.

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 may be, for example, 20% or less, and may be 10% or less.

The precursor sheet can be prepared, for example, by applying an electrode material containing a dispersion medium to a metal foil and then drying it. Examples of dispersion mediums include organic solvents such as butyl butyrate, dibutyl ether, and heptane. There are no particular restrictions on the method for applying the electrode material, and general coating methods can be used. There are also no particular restrictions on the drying temperature, as long as it is a temperature at which the dispersion medium volatilizes.

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.

2. Coated Section Pressing Step The coated section pressing step is a step of pressing the coated section in the thickness direction while transporting the precursor sheet in the first direction. The coated section pressing step may be performed before or after the uncoated section pressing step described below.

The method and conditions for the coated section pressing step are not particularly limited as long as the coated section can be pressed and stretched. One example of a pressing method is a roll press method, in which the coated section is roll-pressed. For example, the coated section 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.

The compression force used in the coated section pressing step is not particularly limited, but it is preferably greater than the compression force used in the uncoated section pressing step described below. This is because wrinkles can occur in the coated section of the precursor sheet when it becomes wet with the electrode material (slurry) containing the dispersion medium, and a large stretching force is required to smooth out these wrinkles.

3. Uncoated Section Pressing Step The uncoated section pressing step is a step of pressing the uncoated section in the thickness direction while conveying the precursor sheet in the first direction, before or after the coated section pressing step. In the uncoated section pressing step, a pair of elastic rolls having a shaft and an elastic body covering the shaft are used to roll-press the uncoated section 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.

By pressing the uncoated portion, the uncoated portion can be stretched, adjusting the difference in elongation between the uncoated portion and 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. Note that 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.

The uncoated portion pressing process will now be explained using the figures. Figure 4(a) is a schematic side view of the uncoated portion pressing process as seen from the width direction of the metal foil. Figure 4(b) is a schematic front view of Figure 4(a) as seen from the first direction D of the precursor sheet. Figures 4(c) and (d) are views of the precursor sheet and elastic roll as seen from the thickness direction (views of Figure 4(b) as seen from the top and bottom of the paper).

As shown in Figures 4(a) and (b), in the uncoated portion pressing process, the precursor sheet 10 is conveyed in a first direction D while passing between a predetermined pair of elastic rolls 20A and 20B. A compressive force is applied by pressing 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 with an elastic body 22 disposed around a shaft 21. Furthermore, as shown in Figure 4(b), the shaft typically protrudes from the elastic body toward the outside of the elastic roll in the axial direction of the shaft.

The material of the shaft is not particularly limited, but a material with a higher Young's modulus than the elastic body is preferable. Examples of shaft materials include metal.

Here, 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.

Furthermore, Young's modulus X and 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 portions. 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 portions.

The material of the elastic body is not particularly limited as long as it satisfies the relationship between the above Young's modulus X and Young's modulus Y, but examples include rubber, urethane, and other resins.

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.

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 cylindrical roll (a roll in which the entire axial direction of the shaft is covered with an elastic body). 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.

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 elastic roll A (20A) has a first end E1 and a second end E2 located outward from 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 the position of the elastic body 22 of elastic roll B (20B).

As shown in Figures 4(b) and (c), when viewed from the thickness direction, elastic roll A (20A) is preferably positioned so that the elastic body 22 contacts the precursor sheet 10 at the position overlapping the uncoated section 3, and so that elastic roll A (20A) does not contact the precursor sheet 10 at the position overlapping the coated section 2. In this case, as shown in Figures 4(b) and (c), elastic roll A (20A) has a first contact section C1 where the elastic body 22 is located at the position overlapping the uncoated section 3, and a non-contact section N1 that does not contact the precursor sheet (coated section 2 in Figure 4(b)) at the position overlapping the coated section 2. Note that if a coated section is located on only one side of the metal foil, non-contact section N1 may be a portion of the precursor sheet that does not contact the metal foil during roll pressing. Furthermore, non-contact section N1 is typically a portion where no elastic body is located. 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 normally come into contact with the precursor sheet during the uncoated portion pressing process. Furthermore, as shown in Figures 4(b) and (c), the elastic roll A (20A) has a first contact portion C1 at each end of the non-contact portion N1.

As shown in Figures 4(b) and (d), elastic roll B (20B) is preferably arranged so that, when observed from the thickness direction, the elastic body 22 contacts the precursor sheet 10 at a position overlapping the uncoated portion 3, and so that the elastic body 22 contacts the precursor sheet 10 at a position overlapping the coated portion 2. In this case, as shown in Figures 4(b) and (d), elastic roll B (20B) has, when observed from the thickness direction, a second contact portion C2 where the elastic body 22 is arranged at a position overlapping the uncoated portion 3, and a third contact portion C3 that contacts the precursor sheet (coated portion 2 in Figure 4(b)) at a position overlapping the coated portion 2. Furthermore, the elastic body at the second contact portion C2 contacts the uncoated portion 3 during the uncoated portion pressing process. On the other hand, the third contact portion C3 contacts the coated portion during the uncoated portion pressing process.

It is also preferable that 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.

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.

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

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 rock salt layer-type active materials such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , spinel-type active materials such as LiMn ₂ O ₄ and Li(Ni _0.5 Mn _1.5 )O ₄ , and olivine-type active materials such as LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , and LiCuPO ₄ .

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 a carbon active material, an oxide active material, and a metal active material. 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 Nb ₂ O ₅ , Li ₄ Ti ₅ O ₁₂ , and SiO. Examples of the metal active material include In, Al, Si, and Sn.

The electrode layer may also contain at least one of a conductive material and a binder, as needed.

Conductive materials include, for example, carbon materials, metal particles, and conductive polymers. Carbon materials include, for example, 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). Binders include, for example, fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic binders.

Examples of applications of the electrodes in this disclosure include Li-ion batteries. The batteries in this disclosure may also be liquid-based batteries in which the electrolyte layer contains a liquid electrolyte (electrolytic solution). Applications of the batteries in this disclosure are not particularly limited, but include, for example, 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. They are particularly preferably used as driving power sources for hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles. The batteries in this disclosure may also be used as power sources for mobile objects other than vehicles (e.g., trains, ships, and aircraft), and may also be used as power sources for electrical appliances such as information processing devices.

Note that this 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 concept described in the claims of this disclosure and that provides similar effects is within the technical scope of this disclosure.

[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.

As shown in Figure 5, it was confirmed that the first load applied 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.

[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.

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 electrode sheet surface (bottom). 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 electrode sheet surface (top), and the shear stress on the surface (bottom) also decreased to 3.43. In this way, it was confirmed that using elastic bodies with different Young's moduli reduces the shear stress applied to the coated area, preventing breakage and streaking when the material rides up on the coated area.

DESCRIPTION OF SYMBOLS 1 metal foil 2 coated portion 3 uncoated portion 10 precursor sheet 21 shaft 22 elastic body 20 elastic roll 20A elastic roll A
20B...Elastic roll B

Claims (4)

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