Method for manufacturing lithium ion battery electrode

Abstract

To suppress an occurrence of the poor appearance of a lithium ion battery electrode.SOLUTION: A method for manufacturing a lithium ion battery electrode includes: a preparation step of preparing at least one object to be packaged including a substrate and an electrode active material layer formed by disposing electrode active material particles on the substrate; a packaging step of packaging the at least one object to be packaged to form an electrode material; and a passing step of allowing the electrode material to pass between a pair of rollers. When V1 represents a peripheral speed of the pair of rollers and V2 represents a speed at which the electrode material passes between the pair of rollers, 0.995V2<V1<1.005V2 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for making electrodes for lithium ion batteries. [Background technology]

[0002] When manufacturing an electrode for a lithium ion battery, a roll press machine may be used to compress an electrode active material layer (electrode material) formed by electrode active material particles. Patent Document 1 discloses that an electrode active material layer is placed inside a frame-shaped member, and then vacuum-packaged, and the vacuum package obtained by this vacuum packaging is roll-pressed with a roll press machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-017924 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the vacuum package is roll-pressed, wrinkles may occur on the surface of the vacuum package, and the electrode active material particles may be ejected into the space formed by the wrinkles. If the vacuum package is compressed in a state in which the electrode active material particles are ejected, there is a risk of causing a defect in the appearance of the lithium-ion battery electrode, which is the product after compression.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a method for manufacturing an electrode for a lithium ion battery that can suppress the occurrence of defective appearance. [Means for solving the problem]

[0006] To achieve the above object, a method for manufacturing an electrode for a lithium-ion battery according to the present disclosure includes a preparation step of preparing at least one object to be packaged including a substrate and an electrode active material layer formed by disposing electrode active material particles on the substrate, a packaging step of packaging the at least one object to be packaged to form an electrode material, and a passing step of passing the electrode material between a pair of rollers. When the peripheral speed of the pair of rollers is V1 and the speed at which the electrode material passes between the pair of rollers is V2, 0.995V2 < V1 < 1.005V2 is satisfied.

Effect of the Invention

[0007] According to the method for manufacturing an electrode for a lithium-ion battery of the present disclosure, the occurrence of appearance defects in the electrode for a lithium-ion battery can be suppressed.

Brief Description of the Drawings

[0008] [Figure 1] It is a flowchart of a method for manufacturing an electrode for a lithium-ion battery according to an embodiment. [Diagram 2] It is a diagram for explaining an example of a preparation step according to an embodiment. [Diagram 3] It is a diagram for explaining an example of a packaging step according to an embodiment. [Figure 4] It is a diagram schematically showing the configuration of an electrode material according to an embodiment. [Diagram 5] It is a diagram for explaining an example of a packaging step according to some embodiments. [Figure 6] It is a diagram for explaining an example of a passing step according to an embodiment. [Figure 7] It is a table showing the determination results of the appearance of an electrode for a lithium-ion battery.

Modes for Carrying Out the Invention

[0009] Hereinafter, a method for manufacturing an electrode for a lithium ion battery according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, and does not limit the present disclosure. The embodiment can be arbitrarily modified within the scope of the technical idea of ​​the present disclosure.

[0010] (method) 1 is a flowchart of a method for manufacturing a lithium-ion battery electrode according to one embodiment. As illustrated in FIG. 1, the method for manufacturing a lithium-ion battery electrode includes a preparation step S1, a packaging step S2, and a passing step S3.

[0011] Fig. 2 is a diagram for explaining an example of a preparation step S1 according to one embodiment. In the preparation step S1, an object to be packaged 2 is prepared. The object to be packaged 2 includes a substrate 4 and an electrode active material layer 6 formed by arranging electrode active material particles A on the substrate 4. In one embodiment, as exemplified in Fig. 2, a frame member 8 is arranged on an upper surface 5 of the plate-shaped substrate 4, and electrode active material particles A are supplied into the space inside this frame member 8 to form the electrode active material layer 6.

[0012] In one embodiment, as illustrated in FIG. 2, the electrode active material layer 6 is formed so that the surface 7 is flush with the upper surface 9 of the frame member 8. In some embodiments, the electrode active material layer 6 is formed so that the surface 7 is located above the upper surface 9 of the frame member 8. In some embodiments, when the length from the upper surface 5 of the substrate 4 to the upper surface 9 of the frame member 8 (i.e., the height of the frame member 8) is h1 and the length from the upper surface 5 of the substrate 4 to the surface 7 of the electrode active material layer 6 (i.e., the thickness of the electrode active material layer 6) is h2, the relationship h1≦h2≦h1×1.3 is satisfied. With this configuration, during the passing step S3 described later, interference of the frame member 8 with the pair of rollers 16 can be suppressed, and the electrode active material layer 6 can be sufficiently compressed. The frame member 8 may be configured so that the space inside the frame member 8 is rectangular or circular in plan view.

[0013] The electrode active material particles A include either positive electrode active material particles or negative electrode active material particles. The positive electrode active material particles include, for example, composite oxides of lithium and transition metals (such as LiCoO2), lithium-containing transition metal phosphates (such as LiFePO4), transition metal oxides (such as MnO2), transition metal sulfides (such as MoS2), or conductive polymers (such as polyaniline). The negative electrode active material particles include, for example, particles of carbon-based materials (such as graphite), silicon-based materials (such as silicon), conductive polymers (such as polyacetylene), metals (such as tin), metal oxides (such as titanium oxide), or metal alloys (such as lithium-tin alloys). In addition, for the above-mentioned negative electrode active material particles that do not include lithium or lithium ions, a pre-doping process may be performed to include lithium or lithium ions in the electrode active material particles A.

[0014] In one embodiment, the average particle diameter of the electrode active material particles A is 5 μm or more and 200 μm or less. The average particle diameter of the electrode active material particles A means the particle diameter at 50% of the integrated value (Dv50) in the particle size distribution obtained by the Microtrack method (laser diffraction / scattering method). The Microtrack method is a method of determining the particle size distribution by utilizing scattered light obtained by irradiating particles with laser light.

[0015] In some embodiments, the electrode active material layer 6 is formed by disposing electrode active material particles A coated with a polymer compound on the substrate 4. According to such a method, it becomes easy to keep the volume of the electrode active material layer 6 within a predetermined range, and the amount of change in the volume of the lithium ion battery electrode can be suppressed.

[0016] Fig. 3 is a diagram for explaining an example of the packaging step S2 according to one embodiment. Fig. 4 is a diagram showing a schematic configuration of an electrode material 10 according to one embodiment. In the packaging step S2, the packaging object 2 prepared in the preparation step S1 is packaged to form the electrode material 10. In the embodiment shown in Fig. 3, the packaging object 2 is accommodated in a bag-shaped packaging material 14 having an opening 12 formed therein. Then, the opening 12 of the packaging material 14 is closed, and the packaging material 14 is heat-sealed while reducing the pressure inside the packaging material 14. As a result, an electrode material 10 is formed in which the packaging material 14 is in intimate contact with the packaging object 2, as shown in Fig. 4.

[0017] Fig. 5 is a diagram for explaining an example of the packaging step S2 according to some embodiments. In the embodiment illustrated in Fig. 5, two packaging objects 2A(2) and 2B(2) are prepared by carrying out the preparation step S1. Then, in the packaging step S2, the two packaging objects 2A and 2B are packaged in a common packaging material 14. Then, the opening 12 of the packaging material 14 is closed, and the packaging material 14 is heat-sealed while reducing the pressure inside the packaging material 14, thereby forming an electrode material 10 including the two packaging objects 2A and 2B.

[0018] The packaging material 14 is not particularly limited as long as it is configured to be able to package the object to be packaged 2 to form the electrode material 10. Although not shown, in some embodiments, the packaging step S2 involves heat sealing the object to be packaged 2 in a state where it is sandwiched between two film-like packaging materials 14 from both sides in the upper and lower directions. Then, the internal space of the packaging material 14 is depressurized to form the electrode material 10.

[0019] FIG. 6 is a diagram for explaining an example of the passing step S3 according to an embodiment. In the passing step S3, the electrode material 10 formed in the packaging step S2 is passed through a gap 20 formed between a pair of rollers 16 to compress the electrode material 10. In other words, the electrode material 10 is roll-pressed by a pair of rollers 16. The method of passing the electrode material 10 through the gap 20 is not particularly limited. For example, the electrode material 10 is placed on a belt moving toward the pair of rollers 16, and the electrode material 10 is conveyed toward the gap 20 and passed through the gap 20. Hereinafter, the direction in which the electrode material 10 is conveyed toward the gap 20 is defined as the conveyance direction D1.

[0020] In one embodiment, as illustrated in FIG. 6, a pair of rollers 16 includes an upper roller 16A(16) and a lower roller 16B(16) disposed below the upper roller 16A. In the vertical direction D2, the upper roller 16A is located on the opposite side of the lower roller 16B with the gap 20 therebetween. Each of the upper roller 16A and the lower roller 16B is rotationally driven at the same speed with respect to each other by, for example, an electric motor. Each of the upper roller 16A and the lower roller 16B rotates such that the rotation direction D3 of the upper roller 16A is opposite to the rotation direction D4 of the lower roller 16B. The upper roller 16A rotates such that the lower surface moves along the conveyance direction D1 (rotates counterclockwise in FIG. 6). The lower roller 16B rotates such that the upper surface moves along the conveyance direction D1 (rotates clockwise in FIG. 6).

[0021] In one embodiment, when the peripheral speed of each of the upper roller 16A and the lower roller 16B is V1 and the passing speed at which the electrode material 10 passes through the gap 20 is V2, 0.995V2 < V1 < 1.005V2 is satisfied.

[0022] In one embodiment, the peripheral speed V1 satisfies 3 mm / s < V1 < 350 mm / s. The peripheral speed V1 preferably satisfies 5 mm / s < V1 < 100 mm / s. When the electrode active material particles A are positive electrode active material particles, the peripheral speed V1 more preferably satisfies 5 mm / s < V1 < 30 mm / s. When the electrode active material particles A are positive electrode active material particles, the peripheral speed V1 even more preferably satisfies 5 mm / s < V1 < 15 mm / s. On the other hand, when the electrode active material particles A are negative electrode active material particles, the peripheral speed V1 more preferably satisfies 5 mm / s < V1 < 40 mm / s.

[0023] The peripheral speed V1 is such that the electrode active material particles A are positive electrode active material particles or negative electrode active material particles

[0024] (Function and effect) The function and effect of the method for manufacturing an electrode for a lithium-ion battery according to one embodiment will be described. When the electrode material 10 is roll-pressed by a pair of rollers 16, wrinkles may occur on the surface of the electrode material 10, and the electrode active material particles A may be ejected into the space formed by these wrinkles. If the electrode material 10 is compressed in a state where the electrode active material particles A are ejected, there is a risk of causing appearance defects in the electrode for a lithium-ion battery.

[0025] The inventors focused on the relationship between the peripheral speed V1 and the passing speed V2, and roll-pressed the electrode material 10 with a pair of rollers 16 while changing this relationship (performing the passing step S3), and determined the appearance of the electrode for a lithium-ion battery. The determination method is not particularly limited, but for example, a method of visually determining the presence, absence, and magnitude of warping and distortion of the electrode for a lithium-ion battery is applicable. FIG. 7 is a table showing the determination results of the appearance of the electrode for a lithium-ion battery.

[0026] In Example 1, the electrode material 10 is roll-pressed by a pair of rollers 16 while satisfying V1 = 0.999V2. In Example 2, the electrode material 10 is roll-pressed by a pair of rollers 16 while satisfying V1 = 1.000V2. In Example 3, the electrode material 10 is roll-pressed by a pair of rollers 16 while satisfying V1 = 1.001V2. In Example 4, the electrode material 10 is roll-pressed by a pair of rollers 16 while satisfying V1 = 1.002V2. In Comparative Example 1, the electrode material 10 is roll-pressed by a pair of rollers 16 while satisfying V1 = 1.005V2.

[0027] As shown in FIG. 7, according to the findings of the present inventors, by satisfying 0.995V2 < V1 < 1.005V2, when the electrode material 10 is roll-pressed by a pair of rollers 16, the electrode material 10 is compressed while stretching the wrinkles generated on the surface of the electrode material 10. Thus, it has been found that the occurrence of appearance defects in the electrode for a lithium-ion battery is suppressed. According to the method described in one embodiment, since the electrode material 10 of the electrode for a lithium-ion battery is roll-pressed by a pair of rollers 16 while satisfying 0.995V2 < V1 < 1.005V2, the occurrence of appearance defects in the electrode for a lithium-ion battery can be suppressed.

[0028] By increasing the peripheral speed V1, the amount of production of the electrode for a lithium-ion battery can be increased. However, when the peripheral speed V1 becomes 350 mm / s or more, for example, the wrinkles are rapidly stretched and cracks are generated on the surface of the electrode material 10, and there is a risk of deterioration in yield. Also, as the peripheral speed V1 is increased, the load applied to the pair of rollers 16 increases. For example, the main shaft of the pair of rollers 16 is worn down. For this reason, there is a risk that maintenance time such as replacement of the main shaft increases and productivity decreases. According to the method described in one embodiment, by satisfying 3 mm / s < V1 < 350 mm / s, the productivity of the electrode for a lithium-ion battery can be improved.

[0029] As illustrated and described with reference to FIG. 5, in the packaging step S2 according to some embodiments, two objects to be packaged 2A and 2B are packaged with a common packaging material 14. Therefore, the time required to perform the packaging step S2 can be shortened as compared with the case where the two objects to be packaged 2A and 2B are packaged with different packaging materials 14. Further, in the passing step S3, since the two electrode active material layers 6 can be roll-pressed by loading the electrode material 10 once, the time required to perform the passing step S3 can be shortened. In another embodiment, three or more objects to be packaged 2 are prepared by performing the preparation step S1, and in the packaging step S2, the three or more objects to be packaged 2 are packaged with a common packaging material 14.

[0030] As described above, the method for manufacturing an electrode for a lithium-ion battery according to an embodiment of the present disclosure has been described. However, the present disclosure is not limited to the above-described form, and various modifications can be made without departing from the object of the present disclosure. For example, in some embodiments, the peripheral speed V1 satisfies V2 < V1 < 1.005V2. As shown in FIG. 7, according to the findings of the present inventors, it has been found that by satisfying V2 < V1 < 1.005V2, when the electrode material 10 is roll-pressed by a pair of rollers 16, wrinkles generated on the surface of the electrode material 10 are more preferably stretched. According to such a method, the occurrence of appearance defects in the electrode for a lithium-ion battery can be further suppressed.

[0031] The content described in each of the above embodiments is understood as follows, for example.

[0032] [1] The method for manufacturing an electrode for a lithium-ion battery according to the present disclosure includes a preparation step of preparing at least one object to be packaged including a substrate and an electrode active material layer formed by disposing electrode active material particles on the substrate, a packaging step of packaging the at least one object to be packaged to form an electrode material, and a passing step of passing the electrode material between a pair of rollers. When the peripheral speed of the pair of rollers is V1 and the speed at which the electrode material passes between the pair of rollers is V2, 0.995V2 < V1 < 1.005V2 is satisfied.

[0033] When passing the electrode material between a pair of rollers for compression of the electrode material, wrinkles may occur on the surface of the electrode material, and electrode active material particles may be ejected into the space formed by these wrinkles. If the electrode material is compressed in a state where the electrode active material particles are ejected, there is a risk of causing appearance defects in the resulting product (electrode for lithium-ion battery). According to the findings of the present inventors, by satisfying 0.995V2 < V1 < 1.005V2, when passing the electrode material between a pair of rollers, the wrinkles generated on the surface of the electrode material are stretched while the electrode material is compressed, so it has been found that the occurrence of appearance defects in the electrode for lithium-ion battery is suppressed. According to the method described in [1] above, since the electrode material of the electrode for lithium-ion battery is compressed by a pair of rollers in a state where 0.995V2 < V1 < 1.005V2 is satisfied, the occurrence of appearance defects in the electrode for lithium-ion battery can be suppressed.

[0034] [2] In some embodiments, in the method described in [1] above, V2 < V1 < 1.005V2 is satisfied.

[0035] According to the findings of the present inventors, it has been found that by satisfying V2 < V1 < 1.005V2, when passing the electrode material between a pair of rollers, the wrinkles generated on the surface of the electrode material are more preferably stretched. According to the method described in [2] above, the occurrence of appearance defects in the electrode for lithium-ion battery can be further suppressed.

[0036] [3] In some embodiments, in the method described in [1] or [2] above, 3 mm / s < V1 < 350 mm / s is satisfied.

[0037] By increasing the peripheral speed V1, the amount of manufacturing electrodes for lithium-ion batteries can be increased. However, when the peripheral speed V1 becomes 350 mm / s or more, for example, wrinkles are rapidly stretched and cracks occur on the surface of the electrode material, which may deteriorate the yield. Also, as the peripheral speed V1 is increased, the load on the pair of rollers increases, and the maintenance time for the pair of rollers increases, which may reduce productivity. According to the method described in one embodiment, by satisfying 3 mm / s < V1 < 350 mm / s, the productivity of the electrodes for lithium-ion batteries can be improved.

[0038] [4] In some embodiments, in the method described in any one of [1] to [3] above, the at least one object to be packaged includes a plurality of objects to be packaged, in the packaging step, the plurality of objects to be packaged are packaged with a common packaging material.

[0039] According to the method described in [4] above, compared with the case where a plurality of objects to be packaged are packaged with different packaging materials, the time required to perform each of the packaging step and the passing step can be shortened.

Explanation of Reference Numerals

[0040] 2 Object to be packaged 4 Substrate 6 Electrode active material layer 10 Electrode material 14 Packaging material 16 Roller 16A Upper roller 16B Lower roller 20 Gap A Electrode active material particles S1 Preparation step S2 Packaging step S3 Passing step V1 Peripheral speed V2 Passing speed

Claims

1. A preparation step of preparing at least one packaging object including a substrate and an electrode active material layer formed by disposing electrode active material particles on the substrate; a packaging step of packaging the at least one packaging object to form an electrode material; A passing step of passing the electrode material between a pair of rollers, If the peripheral speed of the pair of rollers is V1 and the speed at which the electrode material passes between the pair of rollers is V2, then 0.995V2<V1<1.005V2 is satisfied. A method for manufacturing electrodes for lithium-ion batteries.

2. V2<V1<1.005V2 is satisfied. The method for producing the electrode for a lithium ion battery according to claim 1 .

3. Satisfying 3mm / s<V1<350mm / s; The method for producing the electrode for a lithium ion battery according to claim 1 or 2.

4. The at least one packaged object includes a plurality of packaged objects; In the packaging step, the plurality of packaging objects are packaged in a common packaging material. The method for producing the electrode for a lithium ion battery according to claim 1 or 2.

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