Battery cell manufacturing method and laser welding apparatus

Abstract

To perform stable laser welding using laser light with a center and a ring.SOLUTION: A battery cell manufacturing method comprises the steps of: preparing a member on which a portion to be welded is formed; and a step of performing laser welding of the portion to be welded using a laser welding apparatus that irradiates the portion to be welded with first laser light and second laser light distributed from laser light on the basis of a corrected first intensity ratio. Correcting the first intensity ratio includes defining a first center of the laser light, defining a second center of the laser light on the basis of a profile of the laser light with the first center as a center of a center diameter, calculating a second intensity ratio between the first laser light and the second laser light on the basis of a profile of the laser light with the second center as a center of the center diameter, and correcting the first intensity ratio such that the second intensity ratio approaches the first intensity ratio.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present technology relates to a battery cell manufacturing method and a laser welding apparatus. [Background technology]

[0002] A prior art document disclosing the configuration of a hairpin welding method is JP 2022-524635 A (Patent Document 1). In the hairpin welding method described in Patent Document 1, a laser beam is generated whose cross section has a circular core area and a ring area surrounding the core area. Copper wires are welded using a predetermined ratio between the diameter of the core area and the outer diameter of the ring area, and a predetermined ratio between the laser output in the core area and the ring area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-524635 Summary of the Invention [Problem to be solved by the invention]

[0004] When laser welding is performed by splitting a laser beam emitted from a single oscillator into an inner center and an outer ring, the laser intensity ratio between the center and the ring in the actually emitted laser beam may differ from the set laser intensity ratio between the center and the ring. In this case, the required welding depth of the welded part may not be satisfied, resulting in unstable welding.

[0005] The present technology has been developed to solve the above-mentioned problems, and aims to provide a battery cell manufacturing method and laser welding device that can perform stable laser welding using a center and a ring with laser light. [Means for solving the problem]

[0006] A battery cell manufacturing method based on the present technology includes the steps of preparing members on which welded portions are to be formed, and laser welding the welded portions using a laser welding device that irradiates the welded portions with first and second laser beams divided from a laser beam based on a corrected first intensity ratio. The laser welding device includes an emitter, an input unit, a controller, a measurement unit, and a calculation unit. The emitter splits a laser beam emitted from a single oscillator into a first laser beam that forms a center and a second laser beam that forms a ring. The input unit inputs a first intensity ratio between the first and second laser beams. The controller adjusts the distribution of the first and second laser beams at the emitter based on the first intensity ratio. The measurement unit measures a profile of the laser beam emitted from the emitter. The calculation unit calculates a second intensity ratio between the first and second laser beams based on the profile measured by the measurement unit. The first intensity ratio is correctable based on the difference between the second intensity ratio and the first intensity ratio calculated by the calculation unit. Correcting the first intensity ratio includes defining an outer diameter of the laser beam formed when the intensity ratio of the first laser beam is input as 100% in the input unit as a center diameter, defining an outer diameter of the laser beam formed when the intensity ratio of the second laser beam is input as 100% in the input unit as a ring diameter, defining a position corresponding to the maximum peak intensity in the profile of the laser beam based on the input first intensity ratio as a first center of the laser beam, calculating a quadratic approximation curve based on the profile of the laser beam within the center diameter with the first center as the center of the center diameter, and calculating a peak of the quadratic approximation curve. defining a position corresponding to the maximum peak intensity in the center diameter as a second center of the laser beam; defining a region within a central diameter with the second center as the first region; defining a region within a ring diameter centered on the second center and outside the first region as the second region; calculating a second intensity ratio between the first laser beam and the second laser beam based on a ratio between a first value obtained by integrating the first region around the axis of the second center and a second value obtained by integrating the second region around the axis of the second center; and correcting the first intensity ratio so that the second intensity ratio approaches the first intensity ratio.

[0007] A laser welding device based on the present technology includes an emission unit, an input unit, a control unit, a measurement unit, and a calculation unit. The emission unit branches a laser beam emitted from a single oscillator into a first laser beam constituting a center and a second laser beam constituting a ring. The input unit inputs a first intensity ratio between the first laser beam and the second laser beam. The control unit adjusts the distribution of the first laser beam and the second laser beam in the emission unit based on the first intensity ratio. The measurement unit measures a profile of the laser beam emitted from the emission unit. The calculation unit calculates a second intensity ratio between the first laser beam and the second laser beam based on the profile measured by the measurement unit. The laser welding device is configured to be able to correct the first intensity ratio based on the difference between the second intensity ratio calculated by the calculation unit and the first intensity ratio. The outer diameter of the laser beam formed when the intensity ratio of the first laser beam is input as 100% in the input unit can be defined as the center diameter, the outer diameter of the laser beam formed when the intensity ratio of the second laser beam is input as 100% in the input unit can be defined as the ring diameter, and a position corresponding to the maximum peak intensity in the profile of the laser beam based on the input first intensity ratio can be defined as the first center of the laser beam. With the first center as the center of the center diameter, a quadratic approximation curve is calculated based on the profile of the laser beam within the center diameter, and a position corresponding to the maximum peak intensity at the apex of the quadratic approximation curve can be defined as the second center of the laser beam. A region within a center diameter with the second center as the center of the center diameter is defined as a first region, a region within a ring diameter centered on the second center and outside the first region is defined as a second region, a second intensity ratio of the first laser beam to the second laser beam is calculated based on the ratio between a first value obtained by integrating the first region around the axis of the second center and a second value obtained by integrating the second region around the axis of the second center, and the first intensity ratio is corrected so that the second intensity ratio approaches the first intensity ratio. Laser welding can be performed by irradiating the welded portion with the first laser beam and the second laser beam distributed based on the corrected first intensity ratio. [Effects of the Invention]

[0008] According to the present technology, stable laser welding can be performed using a laser beam with a center and a ring. [Brief explanation of the drawings]

[0009] [Figure 1] 10A and 10B are schematic diagrams illustrating a state in which a case and a sealing plate of a battery cell are being laser-welded together according to an embodiment of the present technology; [Figure 2] 2 is a block diagram showing the electrical connection relationship between components in the laser welding device. FIG. [Figure 3] 2 is a schematic diagram showing the configuration of a laser beam emitted by a laser welding device. FIG. [Figure 4] 1 is a flowchart illustrating a method of manufacturing a battery cell according to an embodiment of the present technology. [Figure 5] 4 is a graph showing a profile of a laser beam emitted by a laser welding device. [Figure 6] 10 is a graph showing the range of the center diameter of the profile of laser light. [Figure 7] 10 is a graph showing a profile of a laser beam within a range of a center diameter. [Figure 8] 10 is a graph showing the positional relationship between a first center and a second center in a profile of a laser beam. [Figure 9] 10 is a graph showing a region where the laser intensity in the profile of the laser light is circularly integrated. [Figure 10] 10 is a graph showing an example of a relationship between the laser intensity of the first laser light at a first intensity ratio and the laser intensity of the first laser light at a second intensity ratio. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0011] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0012] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0013] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0014] In this specification, the term "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0015] Furthermore, the "battery cell" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), etc. However, the use of the "battery cell" is not limited to in-vehicle use.

[0016] In the drawings, the direction in which the positive and negative terminals of the battery cells are aligned is referred to as the X direction, the direction perpendicular to the direction in which the positive and negative terminals are aligned and the direction in which the case and sealing plate are aligned is referred to as the Y direction, and the direction in which the case and sealing plate are aligned is referred to as the Z direction.

[0017] First, we will explain the configuration of the battery cell 1. As shown in Figure 1, the battery cell 1 includes a case 10 and a sealing plate 11.

[0018] The case 10 is made of a cylindrical, preferably rectangular, member. This results in a rectangular battery cell 1. The case 10 is made of metal. Specifically, the case 10 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0019] An electrode body (not shown) is housed in the case 10. The case 10 has an opening 12. The electrode body is inserted into the case 10 through the opening 12.

[0020] Sealing plate 11 is a plate-like member that seals opening 12 of case 10. Sealing plate 11 is provided with electrode terminals 13. A positive electrode terminal 14 and a negative electrode terminal 15 are arranged side by side in the longitudinal direction (X direction) of sealing plate 11.

[0021] The sealing plate 11 is made of metal. Specifically, the sealing plate 11 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0022] The case 10 and the sealing plate 11 are welded together by a laser welding device 2. After the sealing plate 11 is brought into contact with the opening 12 of the case 10, a laser beam 3 is emitted from the laser welding device 2 to form a welded portion 16, thereby welding the case 10 and the sealing plate 11 together.

[0023] Next, we will explain the laser welding apparatus 2. As shown in Fig. 2, the laser welding apparatus 2 includes an emission unit 21, an input unit 22, a control unit 23, a measurement unit 24, and a calculation unit 25. The emission unit 21, the input unit 22, the control unit 23, the measurement unit 24, and the calculation unit 25 are electrically connected to each other.

[0024] The emission unit 21 branches the laser beam 3 emitted from a single oscillator. Specifically, as shown in FIGS. 2 and 3, the emission unit 21 branches the laser beam 3 into a first laser beam 31 and a second laser beam 32. The first laser beam 31 constitutes a center located on the inside of the laser beam 3. The second laser beam 32 constitutes a ring located on the outside of the laser beam 3. By branching the laser beam 3 into the center and the ring and emitting them, the welded portion 16 irradiated with the laser beam 3 has an appropriate welding range and is likely to ensure a sufficient welding depth.

[0025] The input unit 22 inputs a first intensity ratio between the first laser light 31 and the second laser light 32. The first intensity ratio is a ratio between the laser intensities of the first laser light 31 and the second laser light 32 that is set appropriately.

[0026] The control unit 23 adjusts the distribution of the first laser light 31 and the second laser light 32 in the emission unit 21 based on the first intensity ratio.

[0027] The measuring unit 24 measures the profile of the laser light 3 emitted from the emitting unit 21. The profile of the laser light 3 is obtained by measuring the laser intensity of the laser light 3. The measuring unit 24 is, for example, a general-purpose beam profiler.

[0028] The calculation unit 25 calculates a second intensity ratio between the first laser beam 31 and the second laser beam 32 based on the profile measured by the measurement unit 24. The second intensity ratio will be described in detail later.

[0029] The laser welding device 2 is configured to be able to correct the first intensity ratio based on the difference between the second intensity ratio calculated by the calculation unit 25 and the first intensity ratio after the second intensity ratio is calculated.

[0030] The laser welding device 2 may be configured so that the measuring unit 24 or the calculating unit 25 can be detached from the laser welding device 2 as needed.

[0031] Next, a method for manufacturing a battery cell will be described. In the following description, a method for welding a case and a sealing plate using laser light 3 according to the present technology will be excerpted from the battery cell manufacturing method.

[0032] In order to perform stable laser welding using a laser beam 3 emitted from a single oscillator and using a center and a ring, the laser beam 3 is emitted based on a first intensity ratio between the corrected first laser beam 31 and the second laser beam 32.

[0033] As shown in FIGS. 4 and 5, in order to correct the first intensity ratio, first, the profile 30 of the laser light 3 is measured by the measuring unit 24 from the emission of the laser light 3 at the first intensity ratio (S1).

[0034] 5, the horizontal axis represents the position of the laser beam 3 in a direction perpendicular to the optical axis direction of the laser beam 3. The vertical axis represents the peak intensity of the laser beam 3.

[0035] Profile 30 varies depending on the first intensity ratio. In this embodiment, profile 30 is obtained in which the peak intensity of first laser beam 31 constituting the center is higher than the peak intensity of second laser beam 32 constituting the ring.

[0036] Here, the outer diameter of laser beam 3 formed when the intensity ratio of first laser beam 31 is input as 100% in input unit 22 is defined as center diameter 31D (see FIG. 6 or FIG. 9). Also, the outer diameter of laser beam 3 formed when the intensity ratio of second laser beam 32 is input as 100% in input unit 22 is defined as ring diameter 32D (see FIG. 9).

[0037] Next, a first center C1 of the laser beam 3 is defined (S2). Specifically, a position corresponding to the maximum peak intensity in the profile 30 of the laser beam 3 based on the input first intensity ratio is defined as the first center C1 of the laser beam 3.

[0038] Next, a second center C2 of the laser beam 3 is defined (S3). Specifically, as shown in Fig. 6, the first center C1 is set to the center of the center diameter 31D. The profile 30 of the laser beam 3 in the region outside the center diameter 31D is deleted.

[0039] As shown in Fig. 7, a quadratic approximation curve CL is calculated based on the profile 30 of the laser beam 3 within the center diameter 31D. Next, a vertex P1 of the quadratic approximation curve CL is obtained. The first center C1 is set to x = 0, and the quadratic approximation curve CL is calculated by y = ax 2 Assuming +bx+c, the position of vertex P1 is b / (2a).

[0040] 7 and 8, the position of the laser beam 3 corresponding to the maximum peak intensity at the vertex P1 of the quadratic approximation curve CL is defined as the second center C2 of the laser beam 3. In this embodiment, the position of the laser beam 3 corresponding to the maximum peak intensity of the laser beam 3 within the center diameter 31D, which is the first center C1, differs from the position of the laser beam 3 corresponding to the maximum peak intensity at the vertex P1 of the quadratic approximation curve CL, which is the second center C2, by a dissociation value D1.

[0041] Next, a second intensity ratio is calculated to correct the first intensity ratio (S4). Specifically, as shown in Fig. 9, a first region R1 and a second region R2 are defined in the profile 30. The first region R1 is a region within a center diameter 31D with the second center C2 as the center of the center diameter 31D. The second region R2 is a region within a ring diameter 32D centered on the second center C2 and located outside the first region R1.

[0042] A first value is calculated from the first region R1. The first value is a value obtained by integrating the first region R1 around the axis of the second center C2.

[0043] A second value is calculated from the second region R2. The second value is a value obtained by integrating the second region R2 around the axis of the second center C2.

[0044] A second intensity ratio between the first laser beam and the second laser beam is calculated based on the ratio between the first value and the second value. The first intensity ratio is corrected so that the second intensity ratio approaches the first intensity ratio. The correction of the first intensity ratio is performed, for example, by adding a difference between the second intensity ratio and the first intensity ratio to the first intensity ratio.

[0045] 10 shows an example of correcting the first intensity ratio. A plurality of first intensity ratios set before correction are set in the input unit 22 to obtain a profile of the laser beam 3. In this example, the laser intensities of the first laser beam 31 are set as V1 to V6, respectively, and the laser beam 3 is emitted.

[0046] A second intensity ratio calculated from the obtained profile of the laser beam 3 is obtained corresponding to the first intensity ratio. In this example, when the laser intensity of the first laser beam 31 at the first intensity ratio is V3, the laser intensity of the first laser beam 31 at the second intensity ratio is V5. Furthermore, when the laser intensity of the first laser beam 31 at the first intensity ratio is V5, the laser intensity of the first laser beam 31 at the second intensity ratio is V7. In this case, when the laser intensity of the first laser beam 31 at the first intensity ratio is V5, the first intensity ratio is corrected based on the difference between V5 and V7 so that the laser intensity of the first laser beam 31 at the second intensity ratio also becomes V5.

[0047] In the corrected first intensity ratio, the intensity ratio between the first laser light 31 and the second laser light 32 is preferably in the range of 10:90 to 50:50.

[0048] Next, as shown in Fig. 4, a member on which the welded portion 16 is to be formed is prepared (S5). In this embodiment, the case 10 and the sealing plate 11 are prepared.

[0049] Using the first intensity ratio obtained by the above-described correction, first laser beam 31 and second laser beam 32 distributed based on the corrected first intensity ratio are irradiated onto portion to be welded 16 to perform laser welding (S6). As a result, portion to be welded 16 is formed, and case 10 and sealing plate 11 are welded together.

[0050] When laser welding is performed by splitting a laser beam emitted from a single oscillator into an inner center and an outer ring, it is difficult to measure the laser intensity ratio between the center and the ring. However, by calculating the laser intensity ratio between the center and the ring based on the first intensity ratio and the second intensity ratio described above, the laser intensity ratio between the center and the ring can be quantified.

[0051] When maintenance is performed on the emission unit 21 of the laser welding device 2, if laser welding is performed using the first intensity ratio that was set before the maintenance, the quality of the laser welding may not be equivalent to that before the maintenance. In this case, by calculating the laser intensity ratios of the center and the ring based on the above-mentioned first intensity ratio and second intensity ratio and correcting the first intensity ratio, it is possible to suppress changes in the quality of the laser welding before and after the maintenance.

[0052] In a manufacturing method of a battery cell 1 according to an embodiment of the present technology, the position of the maximum peak intensity of a profile 30 of laser light 3, in which a first laser beam 31 (center) and a second laser beam 32 (ring) are emitted at a first intensity ratio, is determined as a first center C1 of the laser beam 3. A quadratic approximation curve CL is obtained for the profile 30 within a center diameter 31D centered on the first center C1, and the position of a vertex P1 of the quadratic approximation curve CL is determined as a second center C2. A first region R1 and a second region R2 are then defined by the center diameter 31D and the ring diameter 32D centered on the second center C2. A second intensity ratio of the actually emitted laser beam 3 is calculated from the ratio of the values ​​of the circular integrals of the peak intensities in the first region R1 and the second region R2. The first intensity ratio is corrected so that the first intensity ratio approaches the second intensity ratio. The first laser beam 31 and the second laser beam 32, which are distributed based on the corrected first intensity ratio, are irradiated onto a welded portion 16, thereby performing laser welding. This allows the actual measured value of the laser intensity of the laser light 3 to be reflected in the set first intensity ratio, thereby enabling stable laser welding of the battery cells 1 using the laser light 3 with the first laser light 31 (center) and the second laser light 32 (ring).

[0053] In a manufacturing method of a battery cell 1 according to one embodiment of the present technology, by setting the intensity ratio of the first laser light 31 to the second laser light 32 at a ratio of 10:90 to 50:50 in the corrected first intensity ratio, it is possible to perform laser welding that ensures an appropriate welding range and welding depth for the welded portion 16.

[0054] In the laser welding device 2 according to one embodiment of the present technology, the first intensity ratio (set value) between the set first laser beam 31 (center) and the second laser beam 32 (ring) is corrected based on the calculated second intensity ratio (measured value), thereby enabling stable laser welding with minimal change in welding quality.

[0055] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0056] 1 battery cell, 2 laser welding device, 3 laser beam, 10 case, 11 sealing plate, 12 opening, 13 electrode terminal, 14 positive electrode terminal, 15 negative electrode terminal, 16 welded part, 21 emission part, 22 input part, 23 control part, 24 measurement part, 25 calculation part, 30 profile, 31 first laser beam, 31D center diameter, 32 second laser beam, 32D ring diameter, C1 first center, C2 second center, CL quadratic approximation curve, D1 dissociation value, P1 vertex, R1 first region, R2 second region.

Claims

1. preparing a member on which a welded portion is to be formed; and laser welding the welded portion using a laser welding device that irradiates the welded portion with a first laser beam and a second laser beam that are divided from the laser beam based on the corrected first intensity ratio, The laser welding apparatus includes: an emission unit that splits the laser light emitted from a single oscillator into the first laser light constituting a center and the second laser light constituting a ring; an input unit for inputting the first intensity ratio between the first laser beam and the second laser beam; a control unit that adjusts distribution of the first laser light and the second laser light in the emission unit based on the first intensity ratio; a measurement unit that measures a profile of the laser light emitted from the emission unit; a calculation unit that calculates a second intensity ratio between the first laser beam and the second laser beam based on the profile measured by the measurement unit, the first intensity ratio is correctable based on a difference between the second intensity ratio and the first intensity ratio calculated by the calculation unit, Correcting the first intensity ratio includes: an outer diameter of the laser beam formed when the intensity ratio of the first laser beam is input as 100% in the input unit is defined as a center diameter; an outer diameter of the laser beam formed when the intensity ratio of the second laser beam is input as 100% in the input unit is defined as a ring diameter; defining a position corresponding to a maximum peak intensity in the profile of the laser beam based on the input first intensity ratio as a first center of the laser beam; The first center is set as the center of the center diameter, and a quadratic approximation curve is calculated based on the profile of the laser light within the center diameter; defining a position corresponding to a maximum peak intensity at an apex of the quadratic approximation curve as a second center of the laser light; A region within the center diameter with the second center as the center of the center diameter is defined as a first region, and a region within the ring diameter with the second center as the center and outside the first region is defined as a second region, calculating the second intensity ratio between the first laser light and the second laser light based on a ratio between a first value obtained by integrating the first region around the second center axis and a second value obtained by integrating the second region around the second center axis; correcting the first intensity ratio so that the second intensity ratio approaches the first intensity ratio.

2. 2. The method for manufacturing a battery cell according to claim 1, wherein the first intensity ratio is a ratio of the intensity of the first laser light to the intensity of the second laser light of 10:90 to 50:

50.

3. an emission unit that splits a laser beam emitted from a single oscillator into a first laser beam constituting a center and a second laser beam constituting a ring; an input unit for inputting a first intensity ratio between the first laser beam and the second laser beam; a control unit that adjusts distribution of the first laser light and the second laser light in the emission unit based on the first intensity ratio; a measurement unit that measures a profile of the laser light emitted from the emission unit; a calculation unit that calculates a second intensity ratio between the first laser beam and the second laser beam based on the profile measured by the measurement unit, the first intensity ratio is correctable based on a difference between the second intensity ratio and the first intensity ratio calculated by the calculation unit, an outer diameter of the laser beam formed when the intensity ratio of the first laser beam is input as 100% in the input unit is defined as a center diameter; an outer diameter of the laser beam formed when the intensity ratio of the second laser beam is input as 100% in the input unit is defined as a ring diameter; a position corresponding to a maximum peak intensity in the profile of the laser beam based on the input first intensity ratio can be defined as a first center of the laser beam; The first center is set as the center of the center diameter, and a quadratic approximation curve is calculated based on the profile of the laser light within the center diameter; a position corresponding to a maximum peak intensity at a vertex of the quadratic approximation curve can be defined as a second center of the laser light; A region within the center diameter with the second center as the center of the center diameter is defined as a first region, and a region within the ring diameter with the second center as the center and outside the first region is defined as a second region, calculating the second intensity ratio between the first laser light and the second laser light based on a ratio between a first value obtained by integrating the first region around the second center axis and a second value obtained by integrating the second region around the second center axis; The first intensity ratio can be corrected so that the second intensity ratio approaches the first intensity ratio; a laser welding device capable of performing laser welding by irradiating a portion to be welded with the first laser beam and the second laser beam distributed based on the corrected first intensity ratio;

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