JP7708050B2 - 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 onto a long metal foil.

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 discloses a roll pressing method using a roll press machine equipped with a wrinkle prevention device that suppresses the occurrence of wrinkles caused by the roll pressing operation in the coated and uncoated portions of the electrode plate.

Patent No. 5760366 JP 2019-102172 A

As described 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 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.

The inventors have found that when pressing an uncoated portion using an elastic roll, 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.

This disclosure was made in consideration of the above-mentioned circumstances, and its main objective is to provide a method for manufacturing electrodes that can suppress deterioration of quality.

[1]
the coated portion contains an electrode material including at least an active material, and 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; and in the uncoated portion pressing step, a shaft body and an uncoated portion are pressed against each other. a pair of elastic rolls having an elastic body covering the uncoated portion, and performing roll pressing while applying a compressive force that presses the uncoated portion in the thickness direction, using elastic roll A and elastic roll B as the pair of elastic rolls, and performing a process of applying a load to the elastic body of the elastic roll B using a support roll during the roll pressing so as to include an area where the elastic body of the elastic roll B contacts the precursor sheet, and performing the process such that the load applied from the elastic roll A to the elastic roll B is load X and the load applied from the support roll to the elastic roll B is load Y, and the process is performed such that the load Y is larger than the load X.

[2]
The method for producing an electrode according to [1], wherein the support roll is a metal roll or the elastic roll.

[3]
The elastic roll A has two elastic bodies arranged apart from each other as the elastic body, and when a length between outer end portions of the two elastic bodies in a rotation axis direction is _LX1 , a length of the elastic body of the elastic roll B is _LX2 , and a length of a roller portion of the support roll is _LX3 , the _LX2 and the _LX3 are longer than the _LX1 . The method for manufacturing an electrode according to [1] or [2].

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

The present disclosure has the effect of making it possible to manufacture electrodes that can suppress deterioration in quality.

FIG. 1 is a flow diagram illustrating a method for manufacturing an electrode in the present disclosure. FIG. 1 is a diagram for explaining a mechanism by which a problem occurs in the present disclosure. FIG. 11 is a diagram illustrating the effects of the present disclosure. FIG. 2 is a schematic plan view illustrating a precursor sheet in the present disclosure. FIG. 2 is a diagram illustrating an uncoated portion pressing step in the present disclosure. FIG. 13 is a diagram showing the results of an experimental example.

The manufacturing method of the electrode in this disclosure is described in detail below. Herein, when expressing an aspect in which another member is placed on a certain member, the term "above" is used, unless otherwise specified, to include both a case in which another member is placed directly above a certain member so as to be in contact with the certain member, and a case in which another member is placed above a certain member via another member.

1 is a flow diagram showing an example of a 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 portion and an uncoated portion arranged on the metal foil is prepared (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 arranged at an end of the coated portion in a direction perpendicular to the first direction. Next, while the precursor sheet is transported in the first direction, the coated portion is pressed in the thickness direction (coated portion pressing process). Then, while the precursor sheet is transported in the first direction, the uncoated portion is pressed in the thickness direction (uncoated portion pressing process). In FIG. 1, the uncoated portion pressing process is performed after the coated portion pressing process, but may be performed before the coated portion pressing process. In the uncoated portion pressing process, a pair of elastic rolls are used to apply a compressive force that presses the uncoated portion in the thickness direction while performing roll pressing. In the roll press, a predetermined load is applied to a predetermined area of the elastic roll B by the support roll. Here, in this disclosure, the "thickness direction" is synonymous with the lamination direction of the metal foil and the coating portion. Also, in this disclosure, the "axial direction of the rotating shaft" may be referred to as the "axial direction of the shaft body."

According to the present disclosure, during roll pressing, a process is performed in which the load Y applied from the support roll to the elastic roll B is greater than the load X applied from the elastic roll A to the elastic roll B. Therefore, even if the 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.

As a method for manufacturing an electrode, a method is known in which a precursor sheet in which an electrode mixture is applied onto a metal foil (collecting foil) is pressed. In addition, depending on the presence or absence of an electrode mixture, a difference in elongation rate occurs between the coated and uncoated parts of the metal foil after pressing, which may cause wrinkles in the electrode. In this regard, as in the above-mentioned Patent Document 1, the coated and uncoated parts are pressed separately to suppress the occurrence of wrinkles. In addition, when pressing the uncoated part (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 the above-mentioned compressive force to the uncoated part as well as a deformation force due to deformation of the elastic body. This makes it possible to effectively prevent, for example, breakage of the uncoated part.

Here, the metal foil generally contains a hard tissue harder than the material of the metal foil as an inclusion. By including the hard tissue, for example, the strength of the metal foil can be increased. 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. If multiple voids are connected to each other, they are likely to break. In contrast, in the present disclosure, a pair of elastic rolls are used to perform roll pressing while applying a compressive force in the thickness direction. This allows the uncoated portion to be applied with the compressive force and a deformation force due to the deformation of the elastic body. As a result, it is believed that the generation 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 in a direction perpendicular to the thickness direction. In other words, the deformation force acts in the same direction as the tensile force and is a force that stretches the metal foil in the same way as the tensile force.

The mechanism by which the problem occurs in this disclosure will be described with reference to FIG. 2. FIG. 2(a) is a schematic side view of the precursor sheet and a pair of elastic rolls viewed from the direction of the rotation axis of the elastic rolls. FIG. 2(b) is a schematic front view of FIG. 2(a) viewed from the first direction of the metal foil. Note that the precursor sheet is omitted in FIG. 2(b). Also, FIGS. 2(c) and (d) are schematic front views and partial front views illustrating a case where the elastic roll runs over the coating portion. As shown in FIGS. 2(a) and (b), when a pair of elastic rolls 20A and 20B are used for roll pressing on the uncoated portion 3, the shape of the elastic roll A may be transferred to the elastic roll B, causing distortion (unevenness) in the elastic roll B. In addition, due to the nature of roll pressing, a compressive force is applied to the distorted portion again before the distortion is completely eliminated, so the distortion remains during roll pressing. In other words, permanent distortion occurs in the elastic roll B. In particular, such distortion is more pronounced when the elastic roll A is a stepped roll and the elastic roll B is a cylindrical roll (unstepped roll). When such distortion occurs, the area where the elastic roll B contacts the precursor sheet becomes non-flat. Therefore, as shown in FIG. 2(c), when the elastic roll runs onto the coating section due to meandering or the like in a distorted state and a compressive force is applied to the precursor sheet, as shown in FIG. 2(d), a difference in the distance (clearance) between the elastic roll A and the elastic roll B may occur. In that case, shear stress may concentrate in the area with a small clearance, causing streaks in the coating section or causing the coating section to break. As a result, the quality of the resulting electrode may deteriorate.

In contrast, in the present disclosure, as shown in Figs. 3(a) and (b), a process is performed in which a predetermined load is applied to the elastic roll B (20B) by the support roll 30 during roll pressing. This allows the distortion caused by the pressing of the elastic roll A (20A) to be leveled. In addition, the amount of distortion (depth of the recess) can be reduced. This allows the area of the elastic roll B in contact with the precursor sheet to be flattened, as shown in Fig. 3(c). Therefore, even if the elastic roll A (20A) runs over the coating portion of the precursor sheet, there is no difference in the distance (clearance) between the elastic roll A and the elastic roll B, or the difference is small. As a result, the concentration of shear stress is alleviated, and the occurrence of streaks in the coating portion and the breakage of the coating portion can be suppressed.

Furthermore, in this disclosure, as shown in FIG. 3(b), the region R1 where the load is applied from the support roll 30 to the elastic roll B (20B) includes the region R2 where the elastic body 22 of the elastic roll B (20B) contacts the precursor sheet. Therefore, the width leveled by the support roll of the elastic roll B can be made wider than the width of the precursor sheet. And, even if the elastic roll A rides up on the coating section, the precursor sheet can be prevented from riding up on the shoulder part (the shoulder part of the recess shown in FIG. 3(c)) on the outside of the elastic roll B. As a result, the occurrence of streaks and breaks can be further suppressed. Note that the "region where the elastic body of the elastic roll B contacts the precursor sheet" can be regarded as the region where the elastic body of the elastic roll B contacts the precursor sheet, for example, at the start of roll pressing.

1. Preparation Step The preparation step in the present disclosure is a 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.

Figure 4 is a schematic plan view illustrating a precursor sheet prepared in the preparation process. As shown in Figure 4, the precursor sheet 10 has a metal foil 1 having a longitudinal direction in a 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 disposed on the metal foil. The coated portion becomes an electrode layer through the coated portion pressing process described below.

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 necessary. The active material, conductive material, and binder are described in "4. Electrodes."

The coating 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 the first surface.

The coated portion is preferably arranged along the first direction of the metal foil. Also, the coated portion may be arranged continuously along the first direction D of the metal foil 1 as shown in FIG. 4. On the other hand, the coated portion 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 according to the desired electrode size. The thickness of the coated portion is, for example, 0.2 mm or more, may be 0.3 mm or more, or may be 0.5 mm or more. On the other hand, the thickness of the coated portion is, for example, 1.5 mm or less, 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 second direction perpendicular to the first direction of the metal foil) is not particularly limited and can be adjusted appropriately according to 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. The ratio may be, for example, 90% or less, or may be 80% or less.

The uncoated portion is disposed on the metal foil. The uncoated portion is usually disposed on the same surface of the metal foil as the coated portion. The uncoated portion is, for example, a portion where the metal foil is exposed. As shown in FIG. 4, the uncoated portion 3 in this disclosure is disposed at the end of the coated portion 2 in the direction perpendicular to the first direction D of the metal foil 1 (second direction). Although not shown, the uncoated portion may have a protective layer containing resin at the boundary with the coated portion.

The width of the uncoated portion (length in the second direction) is not particularly limited and can be adjusted appropriately according to 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, the ratio is, 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 drying it. Examples of the dispersion medium include organic solvents such as butyl butyrate, dibutyl ether, and heptane. There are no particular limitations on the method for applying the electrode material, and general application methods can be used. In addition, there are no particular limitations 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. 4. Although not shown, the precursor sheet may also be a sheet having, in a plan view, N rows (N is an integer of 2 or more) 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 portion pressing step The coated portion pressing step is a step of pressing the coated portion in a thickness direction while conveying the precursor sheet in the first direction. The coated portion pressing step may be performed before or after the uncoated portion pressing step described later.

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. An example of a pressing method is 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.

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

3. Uncoated Portion Pressing Step The uncoated portion pressing step in the present disclosure is a 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.

By pressing the uncoated portion, the uncoated portion can be stretched to adjust the difference in elongation with 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.

The details of the uncoated portion pressing process will now be described with reference to Figures 3 and 5. Figure 5(a) is a view of the precursor sheet and elastic roll A in the roll press, observed from the elastic roll A side in the thickness direction. Figure 5(b) is a view of the precursor sheet and elastic roll B in the roll press, observed from the elastic roll B side in the thickness direction. Note that the support roll is omitted in Figure 5(b).

In the uncoated portion pressing process of the present disclosure, as shown in FIG. 3(a), a pair of elastic rolls (20A, 20B) having a shaft body 21 and an elastic body 22 covering the shaft body 21 are used to apply a compressive force to the uncoated portion 3 in the thickness direction while performing roll pressing. In addition, in the roll pressing, a predetermined process is performed using a support roll. By using a pair of elastic rolls, both the compressive force caused by pressing the elastic roll against the precursor sheet and the deformation force of the elastic body caused by the compressive force can be applied to the uncoated portion, so that the breakage of the uncoated portion can be effectively prevented. The compressive force is not particularly limited, but is, for example, 10 kgf/cm or more and 200 kgf/cm or less. Note that, as shown in FIG. 3(b) and the like, in the axial direction of the rotating shaft, the shaft body usually protrudes from the elastic body toward the outside of the elastic roll.

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

The elastic body preferably has a predetermined Young's modulus. The Young's modulus is, for example, 11.1 MPa or more and 86.1 MPa or less. Examples of materials for the elastic body include rubber and resins such as urethane.

The support roll may be a metal roll or the elastic roll described above. As shown in FIG. 3(b) and the like, the metal roll usually has a roller portion 32 and a shaft portion 31 protruding from the roller portion. The roller portion and the shaft portion may be an integral member, or may be different members. The roller portion refers to the portion of the support roll that comes into contact with the elastic roll B. The materials of the metal portion and the shaft body may be the same as the material of the shaft body of the elastic roll described above. The elastic roll is as described above.

As shown in Figures 3(b) and (c), it is preferable that the elastic roll A is a so-called stepped roll in which two or more parts of the shaft body in the axial direction of the rotating shaft are covered with the above-mentioned elastic body. In particular, it is preferable that the elastic roll A is a so-called two-wheel stepped roll in which the above-mentioned elastic body is two elastic bodies arranged apart from each other. In addition, it is preferable that the elastic roll B and the support roll are so-called cylindrical rolls.

As shown in FIG. 3(b), in the rotation axis direction X, when the length between the outer ends of the two elastic bodies 22 of the elastic roll A (20A) is _LX1 , the length of the elastic body 22 of the elastic roll B (20B) is _LX2 , and the length of the roller portion 32 of the support roll 30 is _LX3 , it is preferable that _LX2 and _LX3 are longer than _LX1 .

_LX1 is usually equal to or greater than the length of the metal foil in the second direction. Also, _LX2 ( _LX2 / _LX1 ) relative to _LX1 and _LX3 ( _LX3 / _LX1 ) relative to _LX1 are each, for example, equal to or greater than 1.1, may be equal to or greater than 1.2, or may be equal to or greater than 1.3. On the other hand, _LX2 / _LX1 and _LX3 / _LX1 are each, for example, equal to or less than 2.0, may be equal to or less than 1.8, or may be equal to or less than 1.5.

Furthermore, _LX2 and _LX3 may be the same or different. _LX2 and LX3 are the same when, for example, _LX2 / _LX3 is 0.9 or more and _1.1 or less. When _LX2 and _LX3 are different, _LX2 may be longer or shorter than _LX3 . In this case, _LX2 / _LX3 is, for example, 0.7 or more and 1.3 or less.

In addition, in the roll press, a support roll is used to apply a load to the elastic body of elastic roll B so as to encompass the area where the elastic body of elastic roll B comes into contact with the precursor sheet. Furthermore, if the load applied from elastic roll A to elastic roll B is load X and the load applied from the support roll to elastic roll B is load Y, the above process is performed so that load Y is greater than load X. If load Y is the same as or smaller than load X, it becomes difficult to fully eliminate the distortion (dent) that has occurred in roll B.

The difference between the load X and the load Y is not particularly limited as long as X<Y is satisfied. For example, the load X relative to the load Y (Y/X) is, for example, 1.1 or more, may be 1.2 or more, or may be 1.3 or more. On the other hand, Y/X is, for example, 2.0 or less, may be 1.8 or less, or may be 1.5 or less.

The values of load X and load Y are not particularly limited, but are, for example, 10 kgf/cm or more and 200 kgf/cm or less, respectively.

The above process may be performed continuously during roll pressing. Alternatively, the above process may be performed intermittently at any timing during roll pressing. For example, the above process may be performed when it is detected that a strain amount equal to or greater than a threshold value has occurred in the elastic roll B during roll pressing.

In addition, it is preferable that the elastic roll A (20A) is arranged so that the elastic body 22 contacts the precursor sheet 10 at the position overlapping the uncoated portion 3 when observed from the thickness direction, and the elastic roll A (20A) does not contact the precursor sheet 10 at the position overlapping the coated portion 2. In this case, as shown in FIG. 5(a), the elastic roll A (20A) has a first contact portion C1 in which the elastic body 22 is arranged at the position overlapping the uncoated portion 3, and a non-contact portion N1 that does not contact the precursor sheet (coated portion 2 in FIG. 5(a)) at the position overlapping the coated portion 2. Note that when the coated 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. In addition, the non-contact portion N1 is typically a portion where no elastic body is arranged. The elastic body at 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 does not usually come into contact with the precursor sheet during the uncoated portion pressing process. Also, as shown in FIG. 5(a), roll A (20A) has a first contact portion C1 at each end of the non-contact portion N1.

In addition, it is preferable that the elastic roll B (20B) is arranged so that the elastic body 22 contacts the precursor sheet 10 at a position overlapping the uncoated portion 3 when observed from the thickness direction, and the elastic body 22 contacts the precursor sheet 10 at a position overlapping the coated portion 2 when observed from the thickness direction. In this case, as shown in FIG. 5(b), the elastic roll B (20B) has a second contact portion C2 in which the elastic body 22 is arranged at a position overlapping the uncoated portion 3 when observed from the thickness direction, and has a third contact portion C3 in which the elastic body 22 contacts the precursor sheet (coated portion 2 in FIG. 5(b)) at a position overlapping the coated portion 2 when observed from the thickness direction. In addition, the elastic body at 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 coated portion in the uncoated portion pressing process.

It is also preferable that the elastic roll A is disposed on the upper side of the precursor sheet, and the elastic roll B and the support roll are disposed on the lower side of the precursor sheet. It is also preferable that the elastic roll B and the support roll are disposed such that, when viewed from the side as shown in FIG. 3(a), a line connecting the center point of the elastic roll B and the center point of the support roll is parallel to the thickness direction.

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 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.

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. The positive electrode active material is typically an oxide active material. Examples of the oxide active material 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 carbon active material, oxide active material, and 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, if necessary.

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-based binders.

The use of the electrodes in this disclosure includes, for example, Li-ion batteries. The battery in this disclosure may also be a liquid-based battery in which the electrolyte layer contains a liquid electrolyte (electrolytic solution). The use of the batteries in this disclosure is not particularly limited, but may 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. In particular, it is preferable to use the batteries 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 moving objects other than vehicles (for example, railways, ships, and aircraft), and may also be used as power sources for electrical appliances such as information processing devices.

This disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical ideas described in the claims of this disclosure and has similar effects is included within the technical scope of this disclosure.

[Experimental Example 1]
A rubber (elastic body) having a predetermined 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 6(a).

As shown in Figure 6 (a), it was confirmed that the first load creates permanent strain in the rubber, and that the second and subsequent loads do not create stress until the jig moves by the magnitude (depth) of the strain due to the effect of the strain. In this way, it was confirmed that permanent strain occurs in the elastic body when roll pressing is performed using an elastic body.

[Experimental Example 2]
The shear stress applied to the electrode sheet was simulated by CAE analysis under three conditions of permanent deformation (depth of the recess) of 0 μm, 300 μm, and 600 μm. The results are shown in Figure 6 (b). Figure 6 (c) shows an image of the CAE analysis under the condition of permanent deformation of 600 μm.

As shown in Figure 6 (b), it was confirmed that the smaller the amount of permanent strain, the smaller the maximum shear stress applied to the electrode sheet.

[Experimental Example 3-1]
An elastic roll having a diameter of 150 mm and an elastic body thickness of 10 mm was prepared. A load of 131 kgf/cm was applied to this elastic roll to form a permanent set (dent) in the elastic roll, and the amount of permanent set (dent depth) was measured. The results are shown in FIG. 6(d).

[Experimental Example 3-2]
As shown in Fig. 3(b), a roll (support roll) was pressed against the elastic roll on which permanent deformation was formed in Experimental Example 2-1 with a load of more than 131 kgf/cm. The amount of permanent deformation (depth of the depression) after pressing was measured. The results are shown in Fig. 6(d).

As shown in Figure 6 (d), it was confirmed that the amount of permanent deformation can be reduced by pressing a support roll against an elastic roll in which permanent deformation has occurred.

The above experimental results confirmed that by performing a process in which the load Y applied from the support roll to the elastic roll B during roll pressing is greater than the load X applied from the elastic roll A to the elastic roll B, the amount of permanent strain can be reduced and the maximum shear stress applied to the precursor sheet can be reduced. This shows that the electrode manufacturing method disclosed herein can suppress breakage and other problems even if the elastic roll runs onto the coating section due to meandering or the like, and suppress deterioration in the quality of the resulting electrode.

Reference Signs List 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
30...Support roll

Claims (3)

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;
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 transporting the precursor sheet in the first direction, before or after the coated portion pressing step;
having
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,
In the uncoated portion pressing step, a pair of elastic rolls having a shaft body and an elastic body covering the shaft body are used to perform roll pressing while applying a compressive force that presses the uncoated portion in the thickness direction,
As the pair of elastic rolls, an elastic roll A and an 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,
During the roll press, a load is applied to the elastic body B of the elastic roll B using a support roll so as to include an area where the elastic body B of the elastic roll B contacts the precursor sheet;
When a load applied from the elastic roll A to the elastic roll B is a load X and a load applied from the support roll to the elastic roll B is a load Y, the processing is performed so that the load Y is larger than the load X,
the support roll is a metal roll or an elastic roll (excluding an elastic roll having an elastic body softer than the elastic body B),
The elastic roll A has two elastic bodies a arranged apart from each other as the elastic body A,
a length between outer end portions of the two elastic bodies a in a rotation axis direction is _LX1 , a length of the elastic body B of the elastic roll B is _LX2 , and a length of a roller portion of the support roll is _LX3 , wherein the _LX2 and the LX3 _are longer than the LX1 _. The method for manufacturing an electrode according to claim 1 , wherein the support roll is the metal roll or the elastic roll having the same elastic body as the elastic body B. the elastic roll A is disposed such that, when observed from the thickness direction, the elastic body A comes into contact with the precursor sheet at a position overlapping the uncoated portion , and the elastic roll A has a portion that does not come into contact with the precursor sheet at a position overlapping the coated portion ,
2. The method for manufacturing an electrode according to claim 1, wherein the elastic roll B is arranged such that, when observed from the thickness direction, the elastic body B contacts the precursor sheet at a position overlapping the uncoated portion, and the elastic body B contacts the precursor sheet at a position overlapping the coated portion .