Electrode manufacturing method

Abstract

This invention provides a method for manufacturing electrodes that improves processing accuracy when welding metal foil and resin material. [Solution] An electrode manufacturing method according to one aspect of the present disclosure is a method for manufacturing an electrode in which a metal foil is coated with a thermoplastic resin material, comprising: a lamination step of laminating the resin material on the peripheral edge of the metal foil; a first welding step of dividing a region on the resin material into a plurality of regions in a direction intersecting the circumferential direction of the resin material, irradiating a first region of the plurality of regions with a laser to melt the resin material and weld the metal foil and the resin material; and a second welding step of irradiating a second region of the plurality of regions that is different from the first region with a laser after the start of the first welding step, irradiating the resin material with a laser to melt the resin material and weld the metal foil and the resin material.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a method for manufacturing an electrode in which when heating a resin material disposed on a current collector foil and welding the current collector foil and the resin material, the heating device is relatively moved with respect to the resin material, and the current collector foil and the resin material are welded while moving the position where the resin material is heated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the method for manufacturing an electrode disclosed in Patent Document 1, the amount of thermal shrinkage of the current collector foil and the resin material is different. Therefore, the current collector foil may be deformed during welding, and the welding between the current collector foil and the resin material may be incomplete.

[0005] The present disclosure has been made in view of the above circumstances, and provides a method for manufacturing an electrode with improved processing accuracy when welding a metal foil and a resin material.

Means for Solving the Problems

[0006] A method for manufacturing an electrode according to one aspect of the present disclosure is a method for manufacturing an electrode that coats a metal foil with a thermoplastic resin material, a lamination step of laminating the resin material on a peripheral portion of the metal foil, When the region on the resin material is divided into a plurality of regions in a direction intersecting the circumferential direction of the resin material, a laser is irradiated onto the first region of the plurality of regions to melt the resin material and weld the metal foil and the resin material together in a first welding step, The method further includes a second welding step, in which, after the start of the first welding step, a laser is irradiated onto a second region from among the plurality of regions that is different from the first region, to melt the resin material and weld the metal foil and the resin material together. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a method for manufacturing electrodes that improves the processing accuracy when welding metal foil and resin material. [Brief explanation of the drawing]

[0008] [Figure 1] (a) A schematic perspective view of an electrode according to an embodiment of the present disclosure. (b) A top view of an electrode according to an embodiment of the present disclosure. (c) A cross-sectional view of an electrode according to an embodiment of the present disclosure. [Figure 2] This is a flowchart of the method for manufacturing an electrode according to the embodiment of this disclosure. [Figure 3] (a) A cross-sectional view of the fixing step in the electrode manufacturing method according to the embodiment of the present disclosure. (b) A cross-sectional view of the first welding step in the electrode manufacturing method according to the embodiment of the present disclosure. (c) A cross-sectional view after the first welding step in the electrode manufacturing method according to the embodiment of the present disclosure. [Figure 4] This is a top view showing divided regions on a resin material in a method for manufacturing an electrode according to an embodiment of the present disclosure. [Figure 5] (a) A cross-sectional view of the second welding step in the method for manufacturing an electrode according to the embodiment of the present disclosure. (b) A cross-sectional view after the second welding step in the method for manufacturing an electrode according to the embodiment of the present disclosure. [Figure 6] This is a cross-sectional view of the welding step in a conventional electrode manufacturing method. [Modes for carrying out the invention]

[0009] The following describes specific embodiments of this disclosure in detail with reference to the drawings. However, this disclosure is not limited to the following embodiments. Also, for clarity, the following descriptions and drawings have been simplified as appropriate.

[0010] <Electrode configuration> Figure 1(a) is a schematic perspective view of an electrode according to an embodiment of the present disclosure. Figure 1(b) is a top view of an electrode according to an embodiment of the present disclosure. Figure 1(c) is a cross-sectional view of an electrode according to an embodiment of the present disclosure. Note that the right-handed xyz Cartesian coordinate system shown in Figure 1(a) is for convenience only, to illustrate the positional relationships of the constituent elements. In Figure 1(a), the positive z-axis is vertically upward, and the xy-plane is the horizontal plane. This is common to Figures 1 and 3-6, including those described later in Figures 3-6.

[0011] The electrode 1 comprises an active material layer 11, a current collector foil 12, and a resin material 13. Here, the current collector foil 12 is a metal foil. Electrode 1 is an electrode that can be stacked in multiple layers to form an electrode stack used in secondary batteries such as lithium-ion secondary batteries or nickel-metal hydride batteries. The size of electrode 1 is appropriately determined according to the size of the target secondary battery.

[0012] The active material layer 11 is formed on the surface of the current collector foil 12. The active material layer 11 contains an active material; for example, when the active material layer 11 is the positive electrode, it contains a positive electrode active material such as lithium cobaltate, lithium nickelate, or lithium manganeseate. On the other hand, when the active material layer 11 is the negative electrode, it contains a negative electrode active material such as carbon, graphite, or lithium titanate. The active material layer 11 may also optionally contain an electrolyte, a conductive additive, or a binder.

[0013] The size of the active material layer 11 in the xy-plane direction is appropriately determined according to the size of the target electrode 1. Also, the thickness of the active material layer 11 in the z-axis direction is such that when a plurality of electrodes 1 are stacked to form an electrode stack, the resin material 13 can serve as a sealing material for the electrode stack. That is, when a plurality of electrodes 1 are stacked, it is preferable that the distance between the current collector foils 12 is equal to the thickness of the resin material 13 and the thickness of the active material layer 11 is not more than the interlayer distance.

[0014] In FIG. 1(c), the active material layer 11 is formed only on the surface of the current collector foil 12 on the positive z-axis side, but the active material layer 11 may also be formed on the surface of the current collector foil 12 on the negative z-axis side. Also, the active material layer 11 may be formed on both the surface of the current collector foil 12 on the positive z-axis side and the surface on the negative z-axis side. At this time, for example, an active material layer 11 containing a positive electrode active material is formed on the surface of the current collector foil 12 on the positive z-axis side, and an active material layer 11 containing a negative electrode active material is formed on the surface on the negative z-axis side, whereby the electrode 1 as a whole constitutes a bipolar electrode.

[0015] The current collector foil 12 has the active material layer 11 formed on its surface. Also, as shown in FIG. 1(c), the resin material 13 is welded to the peripheral portion of the current collector foil 12. The size of the current collector foil 12 is appropriately determined according to the size of the target electrode 1. The material of the current collector foil 12 is a metal such as aluminum or copper, for example.

[0016] The resin material 13 is welded to the peripheral portion of the current collector foil 12. The resin material 13 functions as a sealing material capable of preventing leakage of the electrolytic solution injected into the space around the active material layer 11 when a plurality of electrodes 1 are stacked to form an electrode stack. The resin material 13 contains a resin having thermoplasticity. Examples of the resin having thermoplasticity include olefin-based resins such as polyethylene and polypropylene, polyethylene terephthalate, acrylic resins, and the like.

[0017] Note that when a plurality of electrodes 1 are laminated to form an electrode laminate, the resin material 13 has a size and a thickness in the z-axis direction such that the resin material 13 can appropriately serve as a sealing material for the electrode laminate. Further, in FIGS. 1(a) and 1(c), the resin material 13 is welded to the positive z-axis side and the negative z-axis side of the peripheral portion of the current collector foil 12, but the resin material 13 may be welded to either the positive z-axis side or the negative z-axis side of the peripheral portion of the current collector foil 12. Further, in FIGS. 1(a) and 1(c), the end faces of the current collector foil 12 are exposed, but the end faces may be covered with the resin material 13.

[0018] <Method for manufacturing electrode> Next, referring to FIGS. 2 to 6, a method for manufacturing an electrode according to an embodiment of the present disclosure will be described. FIG. 2 is a flowchart of the method for manufacturing an electrode according to an embodiment of the present disclosure. FIGS. 3 to 6 show enlarged views of the end portion on the negative y-axis side of the electrode 1 shown in FIG. 1(c).

[0019] First, the resin material 13 is laminated on the peripheral portion of the current collector foil 12 (step S1). For example, when the resin material 13 is welded to the positive z-axis side and the negative z-axis side of the peripheral portion of the current collector foil 12 as shown in FIG. 1(c), the first resin material 13, the current collector foil 12, and the second resin material 13 are laminated in this order. Step S1 is executed by, for example, a manufacturing apparatus having a gripping portion capable of gripping the current collector foil 12 and the resin material 13.

[0020] Subsequently, as shown in FIG. 3(a), the laminated current collector foil 12 and resin material 13 are fixed using fixing members 21 and 22 (step S2). In step S2, for example, the fixing member 21 is pressed from the positive z-axis side, and the fixing member 22 is installed on a flat surface, whereby the current collector foil 12 and the resin material 13 are fixed. However, the pressure value applied when fixing the current collector foil 12 and the resin material 13 is appropriately determined. Further, the fixing members 21 and 22 are pressed by an air cylinder or the like.

[0021] Furthermore, it is preferable that the material of the fixing member 21 is a material that can transmit the laser irradiated from the positive z-axis side, i.e., the fixing member 21 side, in step S3 described later. By allowing the laser to pass through the fixing member 21, welding between the current collector foil 12 and the resin material 13 becomes easier. The material of the fixing member 21 is, for example, quartz glass or a transparent resin such as fluororesin or acrylic resin, which is a material that does not absorb the laser irradiated by the laser irradiation device 3 described later. However, when the laser is irradiated from the negative z-axis side, i.e., the fixing member 22 side, it is preferable that the material of the fixing member 22 is a material that can transmit the laser. That is, it is preferable that the materials of the fixing members 21 and 22 on the side to which the laser is irradiated are materials that can transmit the laser.

[0022] Next, as shown in Figure 3(b), the laser irradiation device 3 irradiates a first region on the resin material 13 with a laser, melting the resin material 13 and welding the current collector foil 12 and the resin material 13 together (step S3).

[0023] Here, the area on the resin material 13 is divided into four regions A, B, C, and D, starting from the inside in the direction intersecting the circumferential direction of the resin material 13, as shown in Figure 4, for example. However, the number of divisions may be 2-3 or 5 or more. Also, parts of one region may overlap with parts of other regions. Furthermore, the width of each region in the direction intersecting the circumferential direction of the resin material 13 does not have to be constant.

[0024] The laser irradiation device 3 irradiates each of these divided regions with a laser. For example, in Figure 3(b), the first region is region A, and the laser is irradiated onto region A. If necessary, multiple laser irradiation devices 3 may be used to irradiate multiple regions with a laser at the same time, or one laser irradiation device 3 may be used to irradiate multiple regions with a laser at the same time. The laser irradiation device 3 may also be located on the side of the fixed member 22.

[0025] As shown in Figure 3(b), the laser irradiation causes the current collector foil 12 in region A to heat up, and the resin material 13 in region A to melt as shown in Figure 3(c). After the resin material 13 melts, it cools and hardens again, causing the current collector foil 12 and the resin material 13 to fuse together.

[0026] The laser wavelength should be such that the metal constituting the current collector foil 12 can absorb the laser. The laser irradiation time and intensity are controlled so that the resin material 13 melts appropriately. The laser scanning method is determined according to the purpose of manufacturing the electrode 1, and for example, an XY plotter method, a galvanoscanning method, a processing stage drive method, a laser oscillator drive method, or a scanning method that combines these scanning methods may be used.

[0027] Next, as shown in Figure 5(a), the laser irradiation device 3 irradiates a region on the resin material 13 that is different from the first region with a laser, melting the resin material 13 and welding the current collector foil 12 and the resin material 13 together (step S4). For example, in Figure 5(a), regions B and C are the second region. When regions B and C are irradiated with a laser, the resin material 13 in regions B and C melts, as shown in Figure 5(b), and the current collector foil 12 and the resin material 13 are welded together.

[0028] Furthermore, step S4 may start before step S3 is completed. In other words, there may be a timing when step S3 and step S4 are executed simultaneously.

[0029] Next, in step S4, after irradiating a region different from the first region with a laser, it is determined whether there are other regions to irradiate with the laser (step S5). If there are other regions to irradiate with the laser (Yes in step S5), the process returns to step S4 and irradiates with the laser again. For example, in step S3, region A may be irradiated with the laser, in step S4, region B may be irradiated with the laser, and then step S4 may be executed again to irradiate region C. In this case, there may be regions that are not irradiated with the laser, such as region D. On the other hand, if there are no other regions to irradiate with the laser (No in step S5), the process ends.

[0030] By dividing the timing and irradiation area of ​​the laser irradiation on the resin material 13, the welding step can be performed such that there are always unmelted areas at the contact points between the current collector foil 12 and the resin material 13 (for example, areas B and C in Figure 4(c), and area A in Figure 5(b)). Since these unmelted areas restrain the current collector foil 12, the effect of suppressing deformation of the current collector foil 12 is obtained. On the other hand, as shown in Figure 6, if the entire contact area between the current collector foil 12 and the resin material 13 is melted simultaneously, the current collector foil 12 is not restrained, causing deformation of the current collector foil 12.

[0031] The order in which the laser is irradiated over multiple regions on the resin material 13 is appropriately determined so that the current collector foil 12 and the resin material 13 can be welded with high precision. However, it is preferable that the region irradiated with the laser in step S3 is located inward in a direction intersecting the circumferential direction of the resin material 13 compared to the region irradiated with the laser in step S4. That is, compared to the order in which the laser is irradiated over regions B and C in step S3 and then over region A in step S4, the order in which the laser is irradiated over region A in step S3 and then over regions B and C in step S4 is more preferable.

[0032] By irradiating with the laser in this order, it becomes possible to weld the current collector foil 12 and the resin material 13 from the inside in a direction intersecting the circumferential direction of the resin material 13. As a result, region A is welded first in step S3, and the current collector foil 12 in the portion of region A is restrained, so deformation of the current collector foil 12 in the direction intersecting the circumferential direction of the resin material 13 is suppressed from region A. Subsequently, when regions B and C are melted in step S4, the current collector foil 12 in the portion of region A is restrained, so deformation of the current collector foil 12 in the direction intersecting the circumferential direction of the resin material 13 is suppressed from region A. As a result, deformation of the entire peripheral edge of the current collector foil 12 is suppressed.

[0033] Furthermore, it is preferable that the width of the region irradiated with the laser in step S3, in the direction intersecting the circumferential direction of the resin material 13, is narrower than the width of the region irradiated with the laser in step S4. In other words, compared to the order in which regions A and B are irradiated with the laser in step S3 and region C is irradiated with the laser in step S4, the order in which region A is irradiated with the laser in step S3 and regions B and C are irradiated with the laser in step S4 is more preferable.

[0034] By narrowing the width of the laser irradiation in step S3, the melting area in step S3 is reduced. This further enhances the effect of suppressing the deformation of the current collector foil 12 on the inner side in the direction intersecting the circumferential direction of the resin material 13.

[0035] As described above, the electrode manufacturing method according to the embodiment of this disclosure divides the laser-irradiated area into multiple regions, melts the resin material in each region, and welds it to the metal foil. As a result, the unmelted areas always restrain the metal foil during the welding step, reducing deformation of the metal foil. This makes it possible to provide an electrode manufacturing method with improved processing accuracy when welding the metal foil and the resin material. [Explanation of Symbols]

[0036] 1 electrode 11 Active material layer 12 Current collector foil 13 Resin materials 21, 22 Fixing members 3. Laser irradiation device A, B, C, D area

Claims

1. A method for manufacturing an electrode, which involves coating a metal foil with a thermoplastic resin material, A lamination step of laminating the resin material onto the peripheral edge of the metal foil, When the region on the resin material is divided into a plurality of regions in a direction intersecting the circumferential direction of the resin material, a first welding step is performed in which a laser is irradiated onto a first region among the plurality of regions to melt the resin material and weld the metal foil and the resin material together, The invention comprises a second welding step, in which, after the commencement of the first welding step, a laser is irradiated onto a second region of the plurality of regions that is different from the first region, thereby melting the resin material and welding the metal foil and the resin material together. A method for manufacturing electrodes.

2. The first region is provided inward in a direction intersecting the circumferential direction compared to the second region. A method for manufacturing an electrode according to claim 1.

3. The width in the first region in the direction intersecting the circumferential direction is shorter than the width in the second region in the direction intersecting the circumferential direction. The method for manufacturing an electrode according to claim 2.

4. The device further includes a fixing step of fixing the laminated metal foil and the resin material using a fixing member made of a material that can transmit the laser, In the first welding step and the second welding step, the laser penetrates the fixing member and irradiates the area on the resin material. A method for manufacturing an electrode according to any one of claims 1 to 3.

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