Manufacturing method of electrode

Abstract

To reduce waviness after a press.SOLUTION: A manufacturing method of an electrode comprises the following steps of (a) to (c) in this order: the step (a) of forming an electrode including a coating part and an uncoating part by coating an electrode material to one part of a front surface of a base material, in which the uncoated part is formed to both ends of the electrode in a width direction, and the width direction is orthogonal to a conveyance direction; the step (b) of heating at least one part of the uncoated part to be 100°C or larger; and the step (c) of compressing the electrode by passing through the electrode to a roll press machine, in which the electrode passes the roll press machine along the conveyance direction.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Japanese Patent Application Laid-Open No. 2021-082504 discloses a step of pressing an active material layer.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An electrode is formed by forming a coated portion (active material layer) and an uncoated portion (blank) on the surface of a substrate. Usually, in order to increase the energy density, the electrode is compressed by a roll press.

[0005]

[0006] In a roll press, the coated portion is in direct contact with the roll. In the coated portion, elongation may occur in the substrate due to the compressive force being transmitted to the substrate. The uncoated portion is thinner than the coated portion. In the uncoated portion, it is considered that the compressive force is difficult to be transmitted to the substrate. Due to the tensile stress caused by the deformation (elongation) of the coated portion, there is a possibility that some elongation may also occur in the substrate of the uncoated portion. However, a difference in elongation remains between the coated portion and the uncoated portion. The difference in elongation may cause undulation in the coated portion. Undulation may make it difficult to handle the electrode. If the electrode has undulation, it may interfere with the assembly of the battery (for example, the lamination operation of the electrode, etc.).

Means for Solving the Problems

[0007] 1. One aspect of the present disclosure has the following configuration. The method for manufacturing an electrode includes the following steps (a) to (c) in this order. (a) By applying an electrode material to a part of the surface of a base material, an electrode including a coated portion and a non-coated portion is formed. (b) At least a part of the non-coated portion is heated to 100°C or higher. (c) The electrode is compressed by passing it through a roll press. The base material includes a metal foil. In plan view, the electrode has a transport direction and a width direction. The width direction is orthogonal to the transport direction. The electrode is passed through a roll press along the transport direction. Each of the coated portion and the non-coated portion extends in the transport direction. In the width direction, the non-coated portions are formed at both ends of the electrode. The coated portion is sandwiched between the non-coated portions.

[0008] Before pressing, by heating the non-coated portion, the strength of the base material can be locally reduced in the non-coated portion. Due to the lower strength of the non-coated portion compared to the coated portion, it is expected that the difference in elongation between the coated portion and the non-coated portion will be reduced. That is, reduction of waviness is expected.

[0009] 2. The method for manufacturing an electrode according to the above "1" may, for example, have the following configuration. The base material includes an aluminum foil and a copper foil. The aluminum foil and the copper foil are bonded to each other. The copper foil has a smaller thickness than the aluminum foil.

[0010] The metal foil may be, for example, a clad material. Aluminum (Al) tends to have a large decrease in strength with heating at 100°C or higher. By having a large proportion of Al foil in the clad material, reduction of waviness is expected.

[0011] 3. The method for manufacturing an electrode according to the above "2" may, for example, have the following configuration. The ratio of the thickness of the aluminum foil to the thickness of the copper foil is from 6 to 13.

[0012] The method for manufacturing an electrode according to any one of the above items "1" to "3" may have, for example, the following configuration. A groove is formed in the non-coated portion. The groove extends in the width direction.

[0013] By forming a groove in the non-coated portion, the strength of the non-coated portion can be reduced. Therefore, reduction of undulation is expected.

[0014] One aspect of the present disclosure may have, for example, the following configuration. The method for manufacturing an electrode includes the following (a) to (c) in this order. (a) By applying an electrode material to a part of the surface of a base material, an electrode including a coated portion and a non-coated portion is formed. (b) At least a part of the non-coated portion is heated to 100°C or higher. (c) The electrode is compressed by passing the electrode through a roll press machine. The base material includes an aluminum foil and a copper foil. The aluminum foil and the copper foil are bonded to each other. The ratio of the thickness of the aluminum foil to the thickness of the copper foil is 6 to 13. In a plan view, the electrode has a transport direction and a width direction. The width direction is orthogonal to the transport direction. The electrode is passed through a roll press machine along the transport direction. Each of the coated portion and the non-coated portion extends in the transport direction. In the width direction, the non-coated portions are formed at both ends of the electrode. The coated portion is sandwiched between the non-coated portions. A groove is formed in the non-coated portion. The groove extends in the width direction.

[0015] Hereinafter, embodiments of the present disclosure (hereinafter may be abbreviated as "the present embodiment") will be described. However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all respects. The present embodiment is non-limiting. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the description of the claims. For example, it is also initially planned that any configuration is extracted from the present embodiment and they are arbitrarily combined.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0017] <Main Terms> "Electrode" is a general term for a monopolar electrode and a bipolar electrode. A monopolar electrode is a positive electrode or a negative electrode. A monopolar electrode is used in a monopolar type battery. A bipolar electrode has a positive electrode active material layer on one surface of a base material and a negative electrode active material layer on the opposite surface of the base material. A bipolar electrode is used in a bipolar type battery. "Battery" may be, for example, a non-aqueous battery. The non-aqueous battery may be, for example, a lithium ion battery.

[0018] Geometric terms should not be construed in a strict sense. Examples of geometric terms include, for example, "parallel", "perpendicular", "orthogonal", etc. For example, "parallel" may deviate somewhat from "parallel" in a strict sense. Geometric terms may include, for example, tolerances, errors, etc. in design, work, manufacturing, etc. The dimensional relationships in each figure may not match the actual dimensional relationships. The dimensional relationships in each figure may be changed to assist the reader's understanding. For example, the length, width, thickness, etc. may be changed. Some configurations may be omitted.

[0019] Unless otherwise specified, the execution order of multiple steps, operations, and actions included in various methods is not limited to the order of description. For example, multiple steps may proceed simultaneously. For example, multiple steps may proceed in sequence.

[0020] The "conveying direction" indicates the direction in which the web (sheet-like workpiece) is conveyed in web handling (roll to roll). The conveying direction may also be referred to as "MD (machine direction)". The width direction may also be referred to as "TD (transverse direction)". In the drawings of the present disclosure, the conveying direction is displayed as the X direction, the width direction is the Y direction, and the thickness direction is the Z direction.

[0021] "Plan view" indicates viewing an object with a line of sight parallel to the thickness direction (Z direction) of the object. The plan view is shown in a plan view.

[0022] <Method for manufacturing an electrode> FIG. 1 is a schematic flowchart of the method for manufacturing an electrode according to the present embodiment. Hereinafter, the "method for manufacturing an electrode according to the present embodiment" may be abbreviated as the "present manufacturing method". The present manufacturing method includes "(a) coating", "(b) heating", and "(c) pressing" in this order.

[0023] <(a) Coating> FIG. 2 is a schematic plan view showing an example of an electrode according to the present embodiment. The present manufacturing method includes forming an electrode 10 including a coated portion 12 and an uncoated portion 13 by coating an electrode material on a part of the surface of a base material 11. The coated portion 12 may also be referred to as, for example, an "active material layer", a "coating film", or the like.

[0024] The base material 11 is in a sheet form. The thickness of the base material 11 may be, for example, either 5 to 100 μm or 10 to 50 μm. The base material 11 includes a metal foil. The base material 11 may be composed of, for example, a single metal foil. The base material 11 may include, for example, a plurality of metal foils (metal layers). The base material 11 may include at least one selected from the group consisting of, for example, Al foil, copper (Cu) foil, titanium (Ti) foil, nickel (Ni) foil, and stainless steel (SUS) foil. In the present embodiment, for example, the Al foil shall include Al alloy foil. The Al foil may include, for example, any Al alloy from the 1000 series to the 8000 series described in "JIS H 4000". The same applies to other metal foils (such as Cu foil).

[0025] The base material 11 may include, for example, a clad material. For example, the base material 11 may be formed by laminating an Al foil and a Cu foil together. The clad material is, for example, suitable for a bipolar electrode. In the clad material, the Cu foil may have a smaller thickness than the Al foil. The thickness (T Cu ) of the Al foil to the thickness (T Al ) of the Cu foil, the ratio (T Al / T Cu ) may be, for example, 6 to 13. The ratio (T Al / T Cu ) may be, for example, either 8 or more, or 10 or more. The ratio (T Al / T Cu ) may be either 10 or less, or 8 or less.

[0026] The electrode material contains an active material. In addition to the active material, the electrode material may further contain, for example, a conductive material, a binder, and the like. The active material can cause an electrode reaction. The positive electrode active material may contain at least one selected from the group consisting of, for example, lithium nickel composite oxides and lithium iron phosphate. The negative electrode active material may contain at least one selected from the group consisting of, for example, graphite, silicon (Si), silicon oxide (SiO), and lithium titanate. The conductive material can form a conductive path within the active material layer. The conductive material may contain, for example, carbon black and the like. The binder can bond solids together. The binder may contain at least one selected from the group consisting of, for example, polyvinylidene fluoride (PVdF), carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR).

[0027] For example, a slurry may be prepared by mixing the electrode material and a dispersion medium. In the conveying direction (X direction), the coating portion 12 may be intermittently formed by intermittently coating the slurry. The coating method is arbitrary. For example, the slurry may be coated by a slot die method. The dispersion medium may contain, for example, N-methyl-2-pyrrolidone (NMP), water, and the like. The coating portion 12 may be formed only on one side of the substrate 11. The coating portion 12 may be formed on both sides of the substrate 11. The coating portion 12 can be dried by any method. For example, the coating portion 12 may be dried by hot air, infrared rays, and the like.

[0028] The coating portion 12 is formed to extend in the X direction. The length (dimension in the X direction) of the coating portion 12 may be, for example, any of 100 mm or more, 200 mm or more, 300 mm or more, 400 mm or more, 500 mm or more, or 600 mm or more. The length of the coating portion 12 may be, for example, any of 1000 mm or less, 900 mm or less, 800 mm or less, or 700 mm or less.

[0029] The coating section 12 may be formed, for example, in a stripe shape. That is, in the width direction (Y direction), the coating section 12 and the non - coating section 13 may be alternately formed. However, in the Y direction, non - coating sections 13 are arranged at both ends of the electrode 10. That is, in the Y direction, the coating section 12 is sandwiched between the non - coating sections 13. The non - coating section 13 is formed to continuously extend in the X direction. The width (dimension in the Y direction) of the non - coating sections 13 at both ends may be, for example, from 1 to 50 mm, or from 3 to 10 mm.

[0030] In the Y direction, the non - coating section 13 sandwiched between the coating sections 12 may have a smaller width compared to the non - coating sections 13 at both ends of the electrode 10. The width (dimension in the Y direction) of the non - coating section 13 sandwiched between the coating sections 12 may be, for example, any of from 0.1 to 10 mm, from 0.5 to 5 mm, or from 1 to 3 mm.

[0031] Grooves 14 may be formed in the non - coating sections 13 at both ends. The grooves 14 extend in the Y direction. By providing the grooves 14, it is expected that the strength of the non - coating section 13 is locally reduced. The width (dimension in the X direction) of the grooves 14 may be, for example, any of from 0.01 to 3 mm, or from 0.1 to 1 mm. The method of forming the grooves 14 is arbitrary. For example, the grooves 14 may be formed by laser processing or the like.

[0032] A plurality of grooves 14 may be formed. The plurality of grooves 14 may be arranged at regular intervals in the X direction. The interval (pitch) of the grooves 14 in the X direction may be, for example, any of from 1 to 50 mm, or from 3 to 10 mm.

[0033] FIG. 3 is a schematic cross - sectional view showing an example of the grooves in the present embodiment. The grooves 14 extend in the Y direction. In the Y direction, the grooves 14 may extend from one end to the other end of the non - coating section 13. In the Y direction, the grooves 14 may have a smaller length compared to the non - coating section 13. In the Y direction, the ratio of the length (L 0 ) of the grooves 14 to the length (L 1 ) of the non - coating section 13 (L 1 / L0 ) may be any of, for example, 0.2 or more, 0.4 or more, 0.6 or more, or 0.8 or more. The ratio (L 1 / L 0 ) may be any of, for example, 0.8 or less, 0.6 or less, 0.4 or less, or 0.2 or less.

[0034] The groove 14 has a depth (dimension in the Z direction) that does not penetrate the base material 11. The ratio (d / t) of the depth (d) of the groove 14 to the thickness (t) of the base material 11 may be any of, for example, 0.2 or more, 0.4 or more, 0.6 or more, 0.8 or more. The ratio (d / t) may be any of, for example, 0.8 or less, 0.6 or less, 0.4 or less, or 0.2 or less.

[0035] For example, the dimensions of the coating part 12 (active material layer) may be different on the front and back of the base material 11. For example, the first active material layer 12a may have a larger area than the second active material layer 12b. For example, the polarities of the active material layers may be different on the front and back of the base material 11. For example, the first active material layer 12a may be a negative electrode active material layer. For example, the second active material layer 12b may be a positive electrode active material layer. In at least one of the X direction and the Y direction, the dimensional difference between the first active material layer 12a and the second active material layer 12b may be any of, for example, 0.5 to 5 mm, or 1 to 3 mm.

[0036] <(b) Heating> FIG. 4 is a schematic diagram showing an example of heating and pressing in the present embodiment. After the formation of the coating part 12, the electrode 10 is transported in the X direction. This manufacturing method includes heating at least a part of the non - coating parts 13 at both ends to 100°C or more. All of the non - coating parts 13 at both ends may be heated. A part of the non - coating parts 13 at both ends may be heated. The base material 11 includes a metal foil. It is expected that the strength of the non - coating part 13 (metal) will locally decrease due to heating. Furthermore, due to the formation of the grooves 14 (see FIG. 2) at both ends, the strength may further decrease. The reduction of the waviness is expected due to the decrease in the strength of the non - coating parts 13 at both ends.

[0037] FIG. 5 is a table showing the relationship between the heating temperature and strength of a metal material. In FIG. 5, as an example, the properties of an Al alloy (A6063) profile are shown. In Table 1, as the temperature rises, the strength tends to decrease. At temperatures of 100° C. or higher, the decrease in strength is significant. In Table 2, it is considered that the creep phenomenon occurs from around 100° C. Even with different metal types, it is considered that a decrease in strength can occur due to heating at 100° C. or higher.

[0038] The heating method is arbitrary. For example, the heat roll 21 may be pressed against the non-coated portion 13. The heat roll 21 may have a width corresponding to the non-coated portion 13. The heat roll 21 may have a width that does not contact the coating portion 12. The heating temperature (the surface temperature of the heat roll 21) may be adjusted so that the difference in elongation between the coating portion 12 and the non-coated portion 13 becomes smaller. The difference in elongation between the coating portion 12 and the non-coated portion 13 may be, for example, any of 0.1% or less, 0.05% or less, or 0.03% or less. The difference in elongation may be, for example, any of 0% or more, 0.01% or more, or 0.03% or more.

[0039] The heating temperature may be, for example, any of 100° C. or higher, or 150° C. or higher. The heating temperature may be, for example, any of 200° C. or lower, or 150° C. or lower. For example, ridges or the like for forming the groove 14 (see FIG. 2) may be provided on the surface of the heat roll 21.

[0040] <(c) Press> This manufacturing method includes compressing the electrode 10 by passing it through a roll press 22. The electrode 10 is passed through the roll press 22 along the X direction. After heating the non-coated portion 13, passing the electrode 10 through the roll press 22 is expected to reduce undulations. The density of the coating portion 12 (active material layer) can be adjusted, for example, by the line pressure of the roll press 22, the roll gap, etc. The line pressure can be, for example, any of 1 to 20 kN / cm, 3 to 15 kN / cm, or 5 to 10 kN / cm. After pressing, the density of the positive electrode active material layer can be, for example, any of 2 to 4 g / cm 3 , or any of 2.5 to 3.5 g / cm 3 . After pressing, the density of the negative electrode active material layer can be, for example, any of 0.5 to 2 g / cm 3 , or any of 1 to 1.5 g / cm 3 .

[0041] As shown in FIG. 4, immediately after heating, the electrode 10 may be passed through the roll press 22. The time from heating to pressing can be, for example, any of within 60 seconds, within 30 seconds, within 10 seconds, within 5 seconds, or within 1 second.

[0042] After pressing, the electrode 10 (raw sheet) may be cut to fragment the electrode 10. For example, at the cutting line 15 in FIG. 2, cutting the electrode 10 may form a rectangular electrode 10.

Description of Reference Numerals

[0043] 10 Electrode, 11 Substrate, 12 Coating Portion, 12a First Active Material Layer, 12b Second Active Material Layer, 13 Non-Coated Portion, 14 Groove, 15 Cutting Line, 21 Heat Roll, 22 Roll Press.

Claims

1. (a) forming an electrode including a coated portion and an uncoated portion by coating a portion of a surface of a substrate with an electrode material; (b) heating at least a portion of the non-coated portion to 100° C. or higher; and (c) compressing the electrode by passing the electrode through a roll press; in that order, The substrate includes a metal foil, In a plan view, the electrode has a transport direction and a width direction, The width direction is perpendicular to the conveying direction, The electrode is passed through the roll press machine along the transport direction, Each of the coated portion and the non-coated portion extends in the conveying direction, In the width direction, the non-coated portions are formed on both ends of the electrode, and The coated portion is sandwiched between the non-coated portions. A method for manufacturing an electrode.

2. The substrate includes an aluminum foil and a copper foil, The aluminum foil and the copper foil are bonded to each other, and The copper foil has a smaller thickness than the aluminum foil. A method for producing the electrode according to claim 1 .

3. The ratio of the thickness of the aluminum foil to the thickness of the copper foil is 6 to 13; A method for producing the electrode according to claim 2.

4. A groove is formed in the non-coated portion, and The groove extends in the width direction. A method for producing the electrode according to any one of claims 1 to 3.

5. (a) forming an electrode including a coated portion and an uncoated portion by coating a portion of a surface of a substrate with an electrode material; (b) heating at least a portion of the non-coated portion to 100° C. or higher; and (c) compressing the electrode by passing the electrode through a roll press; in that order, The substrate includes an aluminum foil and a copper foil, The aluminum foil and the copper foil are bonded to each other, The ratio of the thickness of the aluminum foil to the thickness of the copper foil is 6 to 13; In a plan view, the electrode has a transport direction and a width direction, The width direction is perpendicular to the conveying direction, The electrode is passed through the roll press machine along the transport direction, Each of the coated portion and the non-coated portion extends in the conveying direction, In the width direction, the non-coated portions are formed on both ends of the electrode, The coated portion is sandwiched between the non-coated portions, A groove is formed in the non-coated portion, and The groove extends in the width direction. A method for manufacturing an electrode.

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