Manufacturing method of sealed battery

Abstract

To provide a method for manufacturing a sealed battery capable of firmly joining a battery case and a sealing plug.SOLUTION: A method for manufacturing a sealed battery includes an injection step S2 of injecting an electrolyte ES into a battery case 10 through an injection port 13h, and a welding step S3 of irradiating a welded portion WP between the battery case 10 and a sealing plug 15 with a laser beam LB while the sealing plug 15 closes the injection port 13h and welding the battery case 10 and the sealing plug 15 together after the injection step S2, and the laser beam LB includes a beam profile including a first beam LB1 capable of evaporating the electrolyte ES and oil present on the surface of the welded portion WP, and a second beam LB2 for keyhole welding a removed portion CP from which at least a part of the electrolyte ES and oil has been removed by irradiation with the first beam LB1 of the welded portion WP.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for producing a sealed battery. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a sealed battery including a battery case having a liquid inlet and a sealing plug that seals the liquid inlet. Specifically, in a liquid inlet step, an electrolyte is injected into the battery case through the liquid inlet. Then, in a welding step, with the liquid inlet closed by the sealing plug, a laser beam is linearly scanned and irradiated onto the annular welded portion of the battery case and the sealing plug to weld the battery case and the sealing plug together. In this welding step, first, a circumferential portion of the annular welded portion of the battery case and the sealing plug is welded by keyhole welding, and then the remaining circumferential portion of the welded portion is welded by heat conduction welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-143656 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the surfaces of the welded parts of the battery case and the sealing plug may be coated with oil (e.g., press oil) used in manufacturing the battery case and the sealing plug, or with the electrolyte injected into the battery case in the electrolyte injection process. In response to this, in the above-mentioned welding process, keyhole welding is first performed on the welded parts. Since keyhole welding is prone to cause voids (blowholes) due to the electrolyte or oil, there is a risk that a large number of voids will be generated in the welded parts where keyhole welding was performed in the above-mentioned welding process. In addition, since sufficient penetration depth cannot be obtained with heat conduction welding, there is a risk that the weld strength will be insufficient in the parts welded by heat conduction welding. For this reason, there is a risk that the above-mentioned manufacturing method will not be able to firmly join the battery case and the sealing plug.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a method for manufacturing a sealed battery that can firmly join a battery case and a sealing plug. [Means for solving the problem]

[0006] One aspect of the present invention relates to a method for manufacturing a sealed battery including a battery case having a liquid inlet and a sealing plug that seals the liquid inlet, the method comprising: a liquid injecting step of injecting an electrolyte into the battery case through the liquid inlet; and a welding step of, after the liquid injecting step, irradiating a welded portion between the battery case and the sealing plug with a laser beam while linearly scanning the welded portion with the sealing plug, thereby welding the battery case and the sealing plug together, the laser beam being a first beam capable of evaporating the electrolyte and oil present on a surface of the welded portion. in, a second beam for keyhole welding a portion of the welded portion from which at least a part of the electrolyte and the oil have been removed by irradiation of the first beam; Surrounding A method for manufacturing a sealed battery having a beam profile.

[0007] In the laser welding step of the above-mentioned manufacturing method, the laser beams are a first beam capable of evaporating the electrolyte and oil (oil content) present on the surface of the welded portion between the battery case and the sealing plug, and a second beam for keyhole welding a removed portion of the welded portion from which at least a part of the electrolyte and at least a part of the oil have been removed by irradiation with the first beam. Integral The battery case and the sealing plug are laser-welded together using a laser beam having a beam profile including:

[0008] Specifically, the first beam is linearly irradiated to the welded portion (portion to be irradiated with laser) between the battery case and the sealing plug, evaporating the electrolyte and oil present on the surface of the welded portion, and the second beam is linearly irradiated to the removed portion from which at least a part of the electrolyte and at least a part of the oil have been removed (disappeared by evaporation) by irradiation with the first beam, and the removed portion is keyhole welded. In this way, by irradiating the welded portion from which at least a part of the electrolyte and at least a part of the oil have been removed with the second beam and keyhole welding the battery case and the sealing plug, it is possible to reduce the occurrence of voids due to the electrolyte and oil, and to perform welding with a deep penetration depth. Therefore, the battery case and the sealing plug can be firmly joined.

[0009] The first beam is a laser beam having a power density capable of evaporating the electrolyte and oil (oil content). The first beam also includes a laser beam having a power density that causes the welding form of the welded parts to be thermal conduction welding (lower than the power density that causes keyhole welding).

[0011] In the laser welding step of the above-mentioned manufacturing method, a laser beam having a beam profile in which the first beam surrounds the second beam is used to laser weld the battery case and the sealing plug. Specifically, for example, a laser beam having a beam profile composed of a central portion having a circular shape in plan view made of the second beam and a ring portion having an annular shape in plan view made of the first beam surrounding the central portion is used.

[0012] By irradiating such a laser beam while linearly scanning the welded portion between the battery case and the sealing plug, a part of the first beam (ring portion) can be irradiated to the welded portion prior to the second beam (center portion). This allows the first beam (ring portion) to be linearly irradiated to the welded portion to remove the electrolyte and oil from the surface of the welded portion, and the second beam (center portion) to be linearly irradiated to the removed portion of the welded portion from which at least a part of the electrolyte and at least a part of the oil have been removed by irradiation with the first beam (ring portion), thereby keyhole welding the battery case and the sealing plug. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view of a sealed battery according to an embodiment; [Diagram 2] FIG. 13 is a diagram illustrating a liquid injection step according to the embodiment. [Diagram 3] 2 is a flowchart showing the flow of a method for manufacturing a sealed battery according to the embodiment. [Figure 4] FIG. 4 is a diagram showing a laser beam profile according to the embodiment. [Diagram 5] FIG. 2 is a diagram illustrating a welding process according to the embodiment. [Figure 6] 6 is a cross-sectional view of FIG. 5 taken along line B-B. [Figure 7] FIG. 11 is another view illustrating the welding process according to the embodiment. [Figure 8] 1 is a schematic diagram of a laser welding device according to an embodiment. [Figure 9] FIG. 6 is an enlarged view of part C in FIG. 5. [Figure 10] FIG. 13 is a diagram showing the results of an electrolyte removal test using a laser beam. [Figure 11] FIG. 13 shows the results of an oil removal test using a laser beam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Embodiment> Next, a method for manufacturing a sealed battery according to an embodiment will be described. In this embodiment, an example of manufacturing a lithium ion secondary battery 1 as a sealed battery will be described. Fig. 1 is a perspective view of the lithium ion secondary battery 1 according to the embodiment. Fig. 2 is a diagram for explaining a liquid injection step, which is a manufacturing process of the lithium ion secondary battery 1, and shows a cross-sectional view of an assembly structure 1A after an assembly step, which is a manufacturing process of the lithium ion secondary battery 1, has been completed.

[0015] The lithium ion secondary battery 1 includes a battery case 10, an electrode assembly 20 housed inside the battery case 10, a positive electrode terminal 50, and a negative electrode terminal 60 (see FIG. 2). The battery case 10 includes a rectangular box-shaped case body 11 and a lid 13 that closes the opening of the case body 11. A liquid filling port 13h is formed in the lid 13 of the battery case 10. A sealing plug 15 that seals the liquid filling port 13h is welded to the lid 13. A connection portion 52 of a positive electrode terminal 50 is joined to a positive electrode plate 21 that constitutes the electrode assembly 20. A connection portion 62 of a negative electrode terminal 60 is joined to a negative electrode plate 31 that constitutes the electrode assembly 20.

[0016] A manufacturing method of the lithium ion secondary battery 1 will be described in detail below. Fig. 3 is a flowchart showing the flow of the manufacturing method of the lithium ion secondary battery 1. First, in step S1 (assembly step), components of the lithium ion secondary battery 1 are assembled to fabricate an assembled structure 1A. Specifically, a positive electrode plate 21, a negative electrode plate 31, and a separator (not shown) are wound together to fabricate an electrode body 20 (see Fig. 2). In addition, a positive electrode terminal 50 and a negative electrode terminal 60 are assembled to the lid portion 13.

[0017] Thereafter, the connection portion 52 of the positive terminal 50 is joined to the positive electrode plate 21 constituting the electrode body 20. Furthermore, the connection portion 62 of the negative electrode terminal 60 is joined to the negative electrode plate 31 constituting the electrode body 20. Thereafter, the electrode body 20 is housed inside the case body 11, and the opening of the case body 11 is closed by the lid portion 13. In this state, the lid portion 13 and the case body 11 are welded together. As a result, the case body 11 and the lid portion 13 are joined together to form the battery case 10, and an assembled structure 1A is produced (see FIG. 2).

[0018] Next, in step S2 (pouring step), as shown in FIG. 2, the electrolyte ES is poured into the battery case 10 through the filling port 13h of the lid 13 of the assembled structure 1A. The electrolyte ES in this embodiment is a non-aqueous electrolyte having an organic solvent (e.g., ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate) as a solvent and LiPF6 as a solute. Thereafter, in step S3 (welding step), the lid 13 of the battery case 10 and the sealing plug 15 are laser welded together with the filling port 13h closed by the sealing plug 15. The filling port 13h is a cylindrical hole, and the sealing plug 15 is a member having a circular shape in a plan view. In this embodiment, the lid 13 and the sealing plug 15 are made of aluminum.

[0019] Here, the welding process of this embodiment will be described in detail. FIG. 8 is a schematic diagram of a laser welding apparatus 100 used in this embodiment. The laser welding apparatus 100 includes a fiber laser oscillator 110 and a head unit 120. The fiber laser oscillator 110 and the head unit 120 are connected by a fiber cable 130. The fiber laser oscillator 110 includes a first laser module 113 that generates a first beam LB1, a first power source 111 that supplies power to the first laser module 113, a second laser module 114 that generates a second beam LB2, and a second power source 112 that supplies power to the second laser module 114. This fiber laser oscillator 110 emits a laser beam LB that is a combination of the first beam LB1 and the second beam LB2.

[0020] Specifically, as shown in Fig. 4, the fiber laser oscillator 110 generates a laser beam LB having a beam profile in which a first beam LB1 surrounds a second beam LB2, and emits this laser beam LB toward the head unit 120. More specifically, the laser beam LB has a beam profile composed of a central portion having a circular shape in a planar view made of the second beam LB2, and a ring portion having an annular shape in a planar view made of the first beam LB1 surrounding this central portion (see Fig. 4). In this embodiment, a HighLighit FL4000CSM-ARM manufactured by Coherent Corporation is used as the fiber laser oscillator 110.

[0021] The head unit 120 is a known head unit (optical head), and irradiates the laser beam LB emitted from the fiber laser oscillator 110 while linearly scanning the welded portion WP between the lid portion 13 and the sealing plug 15 of the battery case 10, thereby welding the lid portion 13 and the sealing plug 15 of the battery case 10. The welded portion WP has a circular ring shape in a plan view. Therefore, in this embodiment, the laser beam LB welds the lid portion 13 and the sealing plug 15 of the battery case 10 in a circular shape all around.

[0022] Incidentally, the surface of the welded portion WP between the lid portion 13 and the sealing plug 15 may be coated with oil (e.g., press oil) used during the manufacture of the lid portion 13 and the sealing plug 15, or with the electrolyte solution ES injected into the battery case 10 during the liquid injection process.

[0023] In contrast, the first beam LB1 of the laser beam LB in this embodiment has a power density (W / mm 2 The second beam LB2 has a power density (W / mm 2). In this embodiment, the power density of the first beam LB1 is set to a power density at which the welding form of the welded portion WP is heat conduction welding (lower than the power density at which keyhole welding is performed). In detail, the laser beam LB has a beam profile including the first beam LB1 capable of evaporating the electrolyte ES and oil present on the surface of the welded portion WP, and the second beam LB2 that keyhole welds the removed portion CP of the welded portion WP where at least a part of the electrolyte ES and oil has been removed by irradiation with the first beam LB1.

[0024] Therefore, in the welding process of this embodiment, the lid portion 13 and the sealing plug 15 of the battery case 10 are laser welded together using a laser beam LB having a beam profile including a first beam LB1 capable of evaporating the electrolyte ES and oil (oil content) present on the surface of the welded portion WP between the lid portion 13 and the sealing plug 15 of the battery case 10, and a second beam LB2 that keyhole welds a removed portion CP of the welded portion WP where at least a portion of the electrolyte ES and at least a portion of the oil have been removed by irradiation with the first beam LB1 (see Figures 5 to 9).

[0025] Specifically, the first beam LB1 is linearly irradiated to the welded portion WP (a portion to be irradiated with laser) having a circular shape in a plan view, and the electrolyte ES and oil (oil content) present on the surface of the welded portion WP are evaporated, and the second beam LB2 is linearly irradiated to at least a part of the removed portion CP where at least a part of the electrolyte ES and at least a part of the oil have been removed (disappeared by evaporation) by the irradiation of the first beam LB1 in the welded portion WP, and at least a part of the removed portion CP is keyhole welded. Note that FIG. 9 shows a plan view of the beam profile of the laser beam LB irradiated to the welded portion WP, and the removed portion CP by the laser beam LB shown in FIG. 9 is indicated by dashed hatching. Also, in FIG. 9, the scanning direction of the laser beam LB (the first beam LB1 and the second beam LB2) is indicated as DS.

[0026] More specifically, as described above, the laser beam LB has a beam profile in which the first beam LB1 surrounds the second beam LB2. In detail, the laser beam LB has a beam profile that is configured with a central portion that is circular in plan view and is made up of the second beam LB2, and a ring portion that is annular in plan view and is made up of the first beam LB1 surrounding the central portion (see FIG. 4). By irradiating the welded portion WP with such a laser beam LB while linearly scanning the welded portion WP, it is possible to irradiate a part of the first beam LB1 (ring portion) to the welded portion WP prior to the second beam LB2 (central portion) (see FIGS. 5 and 9).

[0027] As a result, the first beam LB1 (ring portion) is irradiated linearly onto the welded portion WP to remove the electrolyte ES and oil from the surface of the welded portion WP, and the second beam LB2 (central portion) is irradiated linearly onto a portion of the removal portion CP (specifically, a portion located in the scanning direction DS relative to the portion irradiated by the second beam LB2; for example, the portion shown by cross-hatching in the removal portion CP by the laser beam LB shown in Figure 9) from which at least a portion of the electrolyte ES and at least a portion of the oil have been removed by irradiation with the first beam LB1 (ring portion), thereby keyhole welding the lid portion 13 and the sealing plug 15 of the battery case 10.

[0028] In this way, by irradiating the second beam LB2 to the welded part WP from which at least a part of the electrolyte ES and at least a part of the oil have been removed, and keyhole welding the lid part 13 of the battery case 10 and the sealing plug 15, it is possible to reduce the occurrence of voids caused by the electrolyte ES and oil (voids formed by gas generated from the electrolyte ES or oil by welding heat) and to perform welding with a deep penetration depth. Therefore, the lid part 13 of the battery case 10 and the sealing plug 15 can be firmly joined.

[0029] 7 is a diagram showing a scanning path of the laser beam LB in the welding process of this embodiment. In this embodiment, as shown by the solid line in FIG. 7, first, irradiation of the laser beam LB is started from a first position P1 located outside the welded part WP having a circular ring shape in a plan view, and the laser beam LB is scanned linearly until it reaches a second position P2 included in the welded part WP. Then, the laser beam LB is scanned in an arc shape over half the circumference of the welded part WP from the second position P2 to the third position P3 of the welded part WP, and then the irradiation of the laser beam LB is temporarily stopped.

[0030] Next, as shown by the dashed line in FIG. 7, the laser beam LB starts to be irradiated from the fourth position P4 located outside the welded portion WP, and the laser beam LB scans linearly until it reaches the third position P3 of the welded portion WP. The laser beam LB is then scanned in an arc shape over the remaining half circumference of the welded portion WP from the third position P3 to the second position P2 of the welded portion WP, completing the welding process. By irradiating the laser beam LB along such a scanning path, a part of the first beam LB1 (ring portion) can be irradiated over the entire circumference of the welded portion WP prior to the second beam LB2 (center portion) (see FIG. 5 and FIG. 9). As a result, the lid portion 13 and the sealing plug 15 of the battery case 10 are welded all around.

[0031] In this embodiment, the output density (W / mm 2 ) is the power density at which the welding form of the welded part WP becomes heat conduction welding (for example, 3574 to 25015 W / mm 2 The power density of the second beam LB2 (W / mm 2 ) is the power density at which the welding form of the welded part WP becomes keyhole welding (for example, 26802 W / mm 2The fiber laser oscillator 110 of this embodiment can adjust (change) the power density value of the first beam LB1 and the power density value of the second beam LB2 independently within a predetermined range. Therefore, in the welding process of this embodiment, the second beam LB2 (having a power density that results in keyhole welding) is irradiated to the welded portion WP melted by the first beam LB1, and the welded portion WP is keyhole welded. In this way, welding with a deep penetration depth can be performed, and the lid portion 13 and the sealing plug 15 of the battery case 10 can be firmly joined.

[0032] <Electrolyte removal test using laser beam> Next, an electrolyte removal test by irradiation with a laser beam will be described. First, an aluminum plate is prepared, and the surface of the plate is coated with electrolyte ES. Then, before the laser beam is irradiated, a quantitative analysis is performed with an EDS (energy dispersive X-ray spectrometer) on the surface of the plate coated with electrolyte ES (hereinafter also referred to as electrolyte-coated surface) to measure the ratio (wt%) of P (phosphorus). P (phosphorus) is a component contained in the electrolyte ES. This measured value is shown as Ref in FIG. 10. Then, the first beam LB1 is irradiated while linearly scanning the electrolyte-coated surface using a laser welding device 100 in which the power density of the second beam LB2 (center portion) is set to 0 and the power density of the first beam LB1 (ring portion) is set to various values.

[0033] In this test, the power density of the first beam LB1 (W / mm 2 ) are set to eight values: 3574, 7147, 10721, 14294, 17868, 21442, 25015, and 26802. Of these, 26802 (W / mm 2) is the power density at which the welding form of the welded part WP is keyhole welding, and the other values ​​are the power densities at which the welding form of the welded part WP is heat conduction welding. Then, quantitative EDS analysis was performed on the surfaces irradiated with the first beam LB1 having different power densities as described above, and the proportion (wt%) of the P component was measured. The results are shown in Figure 10. Note that since the P component is an ingredient contained in the electrolyte ES, if the measured value (wt%) of the P component is smaller than Ref, it can be said that there is an effect of removing (evaporating) at least a part of the electrolyte ES.

[0034] As shown in FIG. 10, the power density of the first beam LB1 is set to 3574 to 25015 (W / mm 2 ), the measured value of the P component (wt%) was smaller than Ref. On the other hand, when the power density value of the first beam LB1 was set to a value within the range of 26802 (W / mm 2 ), the measured value of the P component (wt%) was larger than that of Ref. From this result, it was found that the power density was 3574 to 25015 (W / mm 2 ) can be said to be the first beam that can evaporate the electrolyte ES present on the surface of the welded part WP. Also, the first beam LB1 having a power density that causes the welding form of the welded part WP to be heat conduction welding can be said to be the first beam that can evaporate the electrolyte ES present on the surface of the welded part WP.

[0035] In addition, CT scans were taken of cross sections of the plate coated with electrolyte ES where the first beam LB1 with different power densities was irradiated to investigate the number of voids in the corresponding areas. In this test, cavities with a diameter of 0.05 mm or more were considered to be voids and their number was counted. The results are shown in Table 1 as "Number of voids in electrolyte coating."

[0036] [Table 1]

[0037] As shown in Table 1, no voids were generated in the area irradiated with the first beam LB1 having a power density such that the welding form of the welded part WP is heat conduction welding. On the other hand, many voids were generated in the area irradiated with the first beam LB1 having a power density such that the welding form of the welded part WP is keyhole welding. From this result, it can be said that there is a risk of many voids (blowholes) being generated in the welded part if the welded part WP, which has electrolyte ES on its surface, is irradiated with a laser beam (second beam LB2) having a power density such that the welding form is keyhole welding, without irradiating the welded part WP with a laser beam (first beam LB1) capable of evaporating the electrolyte ES present on the surface of the welded part WP.

[0038] <Oil removal test using laser beam> Next, an oil removal test by irradiating a laser beam will be described. As in the electrolyte removal test described above, an aluminum plate is prepared, and press oil is applied to the surface of the plate. Then, before irradiating the laser beam, a quantitative analysis of the surface of the plate to which the press oil was applied (hereinafter also referred to as the oil-applied surface) was performed using an EDS (energy dispersive X-ray spectrometer) to measure the proportion (wt%) of C (carbon). Note that C (carbon) is a component contained in the press oil. This measured value is shown as Ref in FIG. 11. Then, using a laser welding device 100 in which the power density of the second beam LB2 (center portion) was set to 0 and the power density of the first beam LB1 (ring portion) was set to various values, the first beam LB1 was irradiated while linearly scanning the oil-applied surface.

[0039] In this test, the power density of the first beam LB1 (W / mm 2) were set to eight values: 3574, 7147, 10721, 14294, 17868, 21442, 25015, and 26802. Then, quantitative EDS analysis was performed on the surfaces irradiated with the first beam LB1 with different power densities as described above, and the proportion (wt%) of the C component was measured. The results are shown in Figure 11. Note that since the C component is a component contained in the press oil, when the measured value (wt%) of the C component is smaller than Ref, it can be said that there is an effect of removing (evaporating) at least a part of the press oil.

[0040] As shown in FIG. 11, in this test, the power density of the first beam LB1 was set to 3574 to 26802 (W / mm 2 ), the measured value of the C component (wt%) was smaller than Ref, and it was confirmed that at least a part of the press oil could be removed. Therefore, based on the results of this test and the above-mentioned electrolyte removal test, it was found that the power density was 3574 to 25015 (W / mm 2 ) can be said to be a first beam that can evaporate the electrolyte ES and oil present on the surface of the welded part WP. Also, the first beam LB1 having a power density that causes the welding form of the welded part WP to be heat conduction welding can be said to be a first beam that can evaporate the electrolyte ES and oil present on the surface of the welded part WP.

[0041] In addition, CT scans were taken of cross sections of the plate coated with press oil, where the first beam LB1 with different power densities was irradiated, to investigate the number of voids contained in the corresponding areas. In this test, cavities with a diameter of 0.05 mm or more were considered to be voids, and their number was counted. The results are shown in Table 1 as "Number of voids coated with oil."

[0042] As shown in Table 1, no voids were generated in the area where the first beam LB1 having a power density that results in heat conduction welding of the welded part WP was irradiated. On the other hand, many voids were generated in the area where the first beam LB1 having a power density that results in keyhole welding of the welded part WP was irradiated. Therefore, based on the results of this test and the above-mentioned electrolyte removal test, it can be said that there is a risk of many voids (blowholes) being generated in the welded part if the welded part WP, on whose surface there is electrolyte ES or oil, is irradiated with a laser beam (second beam LB2) having a power density that results in keyhole welding without irradiating the welded part WP with a laser beam (first beam LB1) that can evaporate the electrolyte ES and oil present on the surface of the welded part WP.

[0043] Although the present invention has been described above based on the embodiment, the present invention is not limited to the embodiment, and can be appropriately modified and applied without departing from the gist of the present invention. For example, in the embodiment, the laser beam LB has a beam profile in which the first beam LB1 surrounds the second beam LB2, but the beam profile may be any beam profile as long as it includes the first beam LB1 that can evaporate the electrolyte ES and oil present on the surface of the welded part WP, and the second beam LB2 that keyhole welds the removed part CP where at least a part of the electrolyte ES and oil has been removed by irradiation of the first beam LB1 in the welded part WP. [Explanation of symbols]

[0044] 1. Lithium-ion secondary battery (sealed battery) 10 Battery case 13 Lid 13h Filling port 15 Sealing plug 100 Laser welding equipment 110 Fiber laser oscillator 120 Head Unit CP removal section DS Scanning Direction ES electrolyte LB Laser Beam LB1 First Beam LB2 Second Beam WP Welded part

Claims

[Claim 1] The battery case has a liquid inlet and a sealing plug that seals the liquid inlet. In a method for producing a sealed battery, a liquid injection step of injecting an electrolyte into the battery case through the liquid injection port; a welding step of, after the liquid injection step, irradiating a welded portion between the battery case and the sealing plug with a laser beam while linearly scanning the laser beam in a state in which the liquid injection port is closed with the sealing plug, to weld the battery case and the sealing plug, The laser beam is The first beam is capable of evaporating the electrolytic solution and the oil present on the surface of the welded part, and has a beam profile surrounding a second beam that keyhole welds a removed portion of the welded part from which at least a part of the electrolytic solution and the oil has been removed by irradiation of the first beam. A method for manufacturing a sealed battery.

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