Battery manufacturing method

Abstract

To provide a manufacturing method of a battery capable of securing sufficient welding in a short time.SOLUTION: A manufacturing method of a battery according to the present disclosure is a manufacturing method of a battery including plural electrode bodies 10 and a sealing part. The plural electrode bodies 10 are stacked, and the sealing part includes a welding part A2 that seals a space between end parts A1 of the plural electrode bodies 10. The manufacturing method of the battery includes a step of heat-welding plural sealing members disposed between the end parts A1 of the plural electrode bodies 10 by radiating CO2 laser to the plural sealing members and forming the welding part A2.SELECTED DRAWING: Figure 2D

Description

[[Technical Field]]

[0001] The present disclosure relates to a method for manufacturing a battery. [[Background Art]]

[0002] In the method for manufacturing a power storage device disclosed in Patent Document 1, a laminated body including a plurality of current collectors each provided with an active material layer and a plurality of frame-shaped sealing members is prepared. In the laminated body, a sealing member is disposed between each of the plurality of current collectors. Further, infrared radiation is irradiated to melt the plurality of sealing members, thereby forming a side surface that is constituted by the plurality of sealing members and includes a communication port. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2023-000059 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] The inventors of the present application have discovered the following problem. In such a method for manufacturing a power storage device, infrared radiation is irradiated to melt the sealing member. In order to shorten manufacturing time, the output of the infrared radiation is increased. As a result, the surface of the sealing member carbonizes. Therefore, it is difficult to ensure sufficient welding.

[0005] The present disclosure has been made in view of the above-described problem, and provides a method for manufacturing a battery that can ensure sufficient welding in a short time. [[Means for Solving the Problem]]

[0006] A method for manufacturing a battery according to the present disclosure includes: a plurality of electrode bodies and a sealing portion, the plurality of electrode bodies are stacked, The sealing portion is a welding portion that seals the ends of the plurality of electrode bodies, in a method for manufacturing a battery, The method includes a step of forming the welded portion by irradiating a CO2 laser onto a plurality of sealing members arranged between the ends of the plurality of electrode bodies, thereby heating and welding the plurality of sealing members.

[0007] Furthermore, in the battery manufacturing method described above, the CO2 laser may be irradiated using a galvanometer scanner during the above step.

[0008] Furthermore, in the battery manufacturing method described above, the output of the CO2 laser may be 100W or more and 300W or less, and the scanning speed of the CO2 laser may be 4000mm / sec or more and 6000mm / sec or less.

[0009] Furthermore, in the battery manufacturing method described above, the plurality of sealing members may contain polyolefin.

[0010] Furthermore, in the battery manufacturing method described above, the plurality of sealing members are films having a thickness of 120 μm, and when light having a wavelength of 9.4 μm is irradiated onto the film, and the optical axis of the light extends in the thickness direction of the film, the absorption rate of the film in which the light is absorbed is preferably 10% or more and 30% or less. [Effects of the Invention]

[0011] According to this disclosure, sufficient welding can be ensured in a short time. [Brief explanation of the drawing]

[0012] [Figure 1] This is a flowchart showing the method for manufacturing a battery according to Embodiment 1. [Figure 2A] This is a schematic diagram showing one step in the manufacturing method of a battery according to Embodiment 1. [Figure 2B] This is a schematic diagram showing one step in the manufacturing method of a battery according to Embodiment 1. [Figure 2C]It is a schematic diagram illustrating one step of the battery manufacturing method according to Embodiment 1. [Figure 2D] It is a view taken along line A-A of FIG. 2C. [Figure 2E] It is a schematic diagram illustrating one step of the battery manufacturing method according to Embodiment 1. [Figure 3A] It is a schematic diagram illustrating one step of Modification 1 of the battery manufacturing method according to Embodiment 1. [Figure 3B] It is a schematic diagram illustrating one step of Modification 1 of the battery manufacturing method according to Embodiment 1. [Figure 4A] It is a schematic diagram illustrating one step of an example in which the battery manufacturing method according to Embodiment 1 is applied. [Figure 4B] It is a schematic diagram illustrating the details of one step of an example in which the battery manufacturing method according to Embodiment 1 is applied. [Figure 5A] It is a graph showing the absorptance versus the wavelength of light. [Figure 5B] It is a schematic diagram illustrating a calculation method for calculating an integrated absorption amount versus the depth from an incident surface. [Figure 5C] It is a schematic diagram illustrating a calculation method for calculating an integrated absorption amount versus the depth from an incident surface. [Figure 5D] It is a graph showing the absorption amount and the integrated absorption amount versus the depth from an incident surface. [Figure 5E] It is a graph showing the absorption amount and the integrated absorption amount versus the depth from an incident surface. [Figure 5F] It is a graph showing the absorption amount and the integrated absorption amount versus the depth from an incident surface. [Figure 6] It is a schematic diagram illustrating one step of Modification 2 of the battery manufacturing method according to Embodiment 1. [Figure 7A] It is a schematic diagram illustrating one step of Modification 3 of the battery manufacturing method according to Embodiment 1. [Figure 7B] It is a schematic diagram showing a main part of the battery according to Embodiment 1. [Figure 8A] It is a schematic diagram illustrating one step of Example 2 in which the battery manufacturing method according to Embodiment 1 is carried out. [Figure 8B]This is a schematic diagram showing one step in Example 2, in which the battery manufacturing method according to Embodiment 1 is implemented. [Figure 9] This is a schematic diagram showing the main components of a battery related to the technology disclosed herein. [Modes for carrying out the invention]

[0013] (Related technologies) Prior to describing specific embodiments applying this disclosure, a battery relating to the technology related to this disclosure will be described with reference to Figure 9. Figure 9 is a schematic diagram showing the main components of a battery relating to the technology related to this disclosure.

[0014] As shown in Figure 9, the battery 900 comprises a plurality of electrode bodies 90. The plurality of electrode bodies 90 are stacked. Each electrode body 90 comprises a negative electrode 92, a foil 94, a positive electrode 91, a separator 93, and a resin film 95. The negative electrode 92, foil 94, positive electrode 91, and separator 93 are stacked in this order. The shapes of the negative electrode 92, foil 94, positive electrode 91, and separator 93 are, for example, film-like bodies or plate-like bodies extending in a roughly square or roughly rectangular shape. When the battery 900 is viewed from above (here, in the positive Z-axis direction), the foil 94 and separator 93 may enclose the negative electrode 92 and positive electrode 91. The resin film 95 may spread out in a frame shape and cover the ends of the foil 94 and separator 93. The resin film 95 may extend in a frame shape so as to enclose the ends of the negative electrode 92 and positive electrode 91. The welded portion A9 of the resin film 95 is formed on one side surface of the multiple laminated electrode bodies 90. The welded portion A9 is formed using infrared radiation. Specifically, infrared radiation is irradiated onto the entire side surface of the laminated resin film 95, heating the entire side surface of the laminated resin film 95. As a result, the resin films 95 fuse together, and the welded portion A9 is formed. The welded portion A9 extends across the entire side surface of the laminated resin film 95. Therefore, to form the welded portion A9, a certain amount of infrared energy and a sufficient irradiation time are required.

[0015] The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the following mode. Also, for clarity of explanation, the following description and drawings have been simplified as appropriate.

[0016] <Embodiment 1> A battery manufacturing method according to Embodiment 1 will be described with reference to Figures 1 and 2A to 2D.

[0017] It should be noted that the right-handed XYZ coordinate system shown in Figure 2A and other drawings is for convenience in explaining the positional relationships of the components. Typically, the positive Z-axis direction is vertically upward, the direction in which the electrode bodies 10 (described later) are stacked, and the XY plane is the horizontal plane; these are common to all drawings. Also, cross-sections are shown in Figures 2A, 2B, 7B, 8A, etc., but hatching has been omitted for clarity.

[0018] As shown in Figure 2A, the electrode bodies 10 are stacked to form a laminate 100 (step ST1).

[0019] The electrode body 10 comprises a negative electrode 2, a foil 4, a positive electrode 1, a separator 3, and a resin film 5. The foil 4 is, for example, a current collector. The negative electrode 2, foil 4, positive electrode 1, and separator 3 are stacked in this order. The negative electrode 2, foil 4, positive electrode 1, and separator 3 are, for example, film-like bodies or plate-like bodies extending in a roughly square or roughly rectangular shape.

[0020] As shown in Figure 2C, when the laminate 100 is viewed from above (in this case, in the positive Z-axis direction), the foil 4 and separator 3 should ideally encompass the negative electrode 2 and the positive electrode 1. The resin film 5 should spread out in a frame shape and cover the edges of the foil 4 and separator 3.

[0021] The resin film 5 may extend in a frame shape so as to encompass the ends of the negative electrode 2 and the positive electrode 1. The end face of end A1 of the resin film 5 is exposed on one side of the laminate 100. The resin film 5 may contain a material that can be welded by irradiation with a CO2 laser. Such a material is, for example, polyolefin. Specifically, the polyolefin is polyethylene or polypropylene. The polyethylene may be, for example, modified polyethylene. The parts where multiple resin films 5 are heat-welded to each other function as sealing parts in the battery. The resin film 5 functions as a sealing member.

[0022] Next, as shown in Figures 2B to 2D, a galvanometer scanner GS is used to irradiate the side surface of the laminate 100 with a CO2 laser (step ST2). The output power of the CO2 laser is preferably between 100W and 300W, and more specifically, 200W. The scanning speed of the CO2 laser is preferably between 4000mm / sec and 6000mm / sec, and more specifically, 5000mm / sec.

[0023] Specifically, the pressure restraint unit PRU is positioned above the end A1 of the resin film 5 of the laminate 100. The pressure restraint unit PRD is positioned below the end A1 of the resin film 5 of the laminate 100. The end A1 of the resin film 5 of the laminate 100 is sandwiched between the pressure restraint unit PRU and the pressure restraint unit PRD. The pressure restraint unit PRU and the pressure restraint unit PRD pressurize and restrain the end A1 of the resin film 5 of the laminate 100.

[0024] Furthermore, the CO2 laser is irradiated onto one side surface of the laminate 100. In other words, the end surface A1 of the resin film 5 exposed on one side surface of the laminate 100 is irradiated with the CO2 laser. Using a galvanometer scanner GS, the CO2 laser is irradiated while scanning one side surface of the laminate 100 with a laser light spot generated by the CO2 laser. In this scanning, the laser light spot moves back and forth at a predetermined pitch on one side surface of the laminate 100. This scanning may also irradiate the entire side surface of the laminate 100 with the CO2 laser.

[0025] Specifically, as shown in Figures 2C and 2D, the laser beam spot repeatedly reciprocates along a predetermined pitch on one side of the laminate 100 in a direction (in this case, the Y-axis direction) that is aligned with the interfaces between the multiple laminated resin films 5.

[0026] In the example shown in Figure 2D, a CO2 laser is irradiated so that the laser beam spot moves along paths P1 to P10. Paths P1 to P10 should ideally extend in the direction along the interface between the ends A1 of the multiple resin films 5 (in this case, the Y-axis direction).

[0027] In path P1, the laser beam spot from the CO2 laser moves from one end to the other of the uppermost layer of resin film 5 in the laminate 100. Note that path P1 extends in the negative Y-axis direction.

[0028] In pass P2, the laser beam spot from the CO2 laser moves in the opposite direction to pass P1 (in this case, the positive Y-axis direction) from a position predetermined to be below the endpoint of pass P1. This predetermined distance is the size of the pitch described above.

[0029] In passes P3 to P10, similar to pass P2, the laser beam spot from the CO2 laser moves in the opposite direction to the previous pass, starting from a position a predetermined distance below the endpoint of the previous pass. This predetermined distance is the size of the pitch described above. The end A1 of the resin film 5 is heated by irradiation with the CO2 laser. As a result, multiple resin films 5 are welded together at the end A1 of the resin film 5. This welding process may be repeated to form a welded portion across the entire side surface of the laminate 100.

[0030] Similarly, the CO2 laser is irradiated to other sides of the laminate 100. The edges A1 of the resin film 5 are welded together on all sides of the laminate 100, forming the welded portion A2 shown in Figure 2E. At the welded portion A2, the multiple resin films 5 are welded together, and the spaces between the multiple resin films 5 are sealed. Therefore, it is difficult for liquids or foreign matter to pass through the welded portion A2. In other words, the spaces between the multiple resin films 5 are blocked, ensuring the airtightness of the laminate 100.

[0031] From the above, a battery 200 can be manufactured. The battery 200 is, for example, a bipolar battery. According to the battery manufacturing method of this embodiment 1, a CO2 laser is irradiated onto the side surface of the laminate 100, and the end A1 of the resin film 5 is welded to the side surface of the laminate 100. As a result, a welded portion A2 is formed. Therefore, the energy is concentrated on the resin film 5, and the end A1 of the resin film 5 is sufficiently welded in a short time.

[0032] Furthermore, according to the battery manufacturing method of this embodiment 1, a galvanoscanner GS is used to irradiate with a CO2 laser. That is, the CO2 laser is irradiated while scanning the side surface of the laminate 100 with a laser light spot from the CO2 laser. This makes it possible to uniformly weld the edge A1 of the resin film 5 on the side surface of the laminate 100.

[0033] Furthermore, in the battery manufacturing method according to this embodiment 1, the resin film 5 contains polyolefin. Also, the output of the CO2 laser is 100W or more and 300W or less. Also, the scanning speed of the CO2 laser is 4000mm / sec or more and 6000mm / sec or less. These factors make it possible to suppress carbonization of the edge A1 of the resin film 5 while shortening the time required for welding the edge A1 of the resin film 5.

[0034] <Example 1> Next, with reference to Figures 3A and 3B, one step of Modification 1 of the battery manufacturing method according to Embodiment 1 will be described.

[0035] The electrode bodies 10 are stacked to form a laminate 100A (step ST21). The laminate 100A shown in Figure 3A has the same configuration as the laminate 100 shown in Figure 2D, except that it includes an opening 5a and a component 6. The opening 5a is located on one side of the laminate 100A. The opening 5a is large enough for a liquid such as an electrolyte to pass through. The liquid is supplied to the inside of the laminate 100A by passing through the opening 5a. Component 6 protrudes from one side of the laminate 100A. Component 6 is, for example, a charging terminal.

[0036] Next, as shown in Figure 3B, a galvanoscanner GS (not shown) is used to irradiate the side surface of the laminate 100A with a CO2 laser (step ST22). Step ST22 is the same as step ST2, except that the laser beam spot from the CO2 laser reciprocates at a predetermined pitch on one side surface of the laminate 100A, avoiding the opening 5a and the component 6.

[0037] In one example shown in Figure 3B, the CO2 laser is irradiated so that the laser beam spot moves along paths P21 to P28.

[0038] In pass P21, the laser beam spot from the CO2 laser moves from one end to the other of the resin film 5, which is the uppermost layer in the laminate 100A.

[0039] In path P22, the laser beam spot from the CO2 laser moves in the opposite direction to path P1, starting from a position a predetermined distance below the endpoint of path P1.

[0040] In passes P23 to P28, similar to pass P22, the laser beam spot from the CO2 laser moves in the opposite direction to the previous pass, starting from a position a predetermined distance below the endpoint of the previous pass.

[0041] However, in passes P24 and P25, once the CO2 laser spot has started moving and reaches the vicinity of one or the other end of aperture 5a, the CO2 laser irradiation is stopped. Then, near the other or one end of aperture 5a, the CO2 laser irradiation is resumed. Furthermore, the CO2 laser spot then resumes moving from the vicinity of the other or one end of aperture 5a.

[0042] Similarly, in path P27, after the laser spot from the CO2 laser begins to move, the irradiation of the CO2 laser is stopped when it reaches the vicinity of the other end of component 6. Then, irradiation of the CO2 laser is resumed near one end of component 6. Furthermore, the laser spot from the CO2 laser resumes moving from the vicinity of one end of aperture 5a.

[0043] Next, the CO2 laser is irradiated to the other sides of the laminate 100A, welding the edges A1 of the resin film 5 to all sides of the laminate 100A. As a result, a welded portion (not shown) is formed. Thus, a battery can be manufactured. In this manufacturing method, energy is concentrated on the resin film 5, and the edges A1 of the resin film 5 are sufficiently welded in a short time. In addition, the opening 5a and the component 6 are not irradiated by the CO2 laser. That is, the CO2 laser is irradiated while scanning with a laser beam spot that follows the shape of the side of the laminate 100A. Furthermore, the depth of the welded portion near the opening 5a and near the component 6 is approximately the same as the depth of the welded portion in other parts of the side of the laminate 100A. Therefore, the degree of design freedom can be improved.

[0044] <Example 1> Next, with reference to Figures 4A and 4B, Example 1, which applies the battery manufacturing method according to Embodiment 1, will be described.

[0045] As shown in Figure 4A, in this embodiment, the thickness of the laminate 100 is 10 mm and the width of the laminate 100 is 200 mm. The processing conditions were a CO2 laser output of 200 W, a CO2 laser scanning speed of 5000 mm / sec, and an irradiation time of 4 sec. Specifically, the irradiation time per pass was 0.04 sec, the number of passes per scan was 10, and the number of scans was 10.

[0046] Steps ST1 and ST2 are carried out. Here, the heat conduction of the resin film 5 to unit location AU1 in step ST2 will be explained. As shown in Figure 4B, a CO2 laser L1 is irradiated onto unit location AU1 of the resin film 5 on the side surface of the laminate 100 using a galvanometer scanner GS (step ST2a). As a result, unit location AU1 of the resin film 5 is heated.

[0047] Next, the side surface of the laminate 100 is scanned with a laser beam spot from the CO2 laser L1 (step ST2b). For example, 0.1 seconds after step ST2a, the CO2 laser is irradiated to a part of the resin film 5 different from the unit location AU1 using a galvanometer scanner GS.

[0048] Next, the side surface of the laminate 100 is scanned with a laser beam spot from the CO2 laser L1 (step ST2c). For example, 0.3 seconds after step ST2a, the surface AU3 of unit location AU1 cools down due to heat dissipation. The deep AU2 of unit location AU1 heats up due to heat conduction from the surface AU3.

[0049] Next, the CO2 laser L1 is irradiated again onto the unit area AU1 of the resin film 5 on the side of the laminate 100 (step ST2d). For example, 0.4 seconds after step ST2a, the unit area AU1 of the resin film 5 is reheated. As a result, the surface AU3 of the unit area AU1, which was cooled in step ST2c, is heated up. In addition, the deep AU2, which was heated in step ST2c, has a higher temperature compared to the surrounding area of ​​the deep AU2.

[0050] As described above, repeated scanning with the CO2 laser L1 laser spot causes the surface AU3 and deep AU2 of unit location AU1 to heat up. This causes the resin films 5 to weld together at the surface AU3 and deep AU2. Furthermore, the surface AU3 of unit location AU1 undergoes repeated heating and cooling cycles, making it less susceptible to carbonization. In addition, the deep AU2 of unit location AU1 gradually heats up due to heat conduction from the surface AU3. Therefore, it is possible to further form the welded area while suppressing carbonization of the surface AU3.

[0051] <Electromagnetic wave absorption characteristics of resin films> Next, with reference to Figure 5A, the electromagnetic wave absorption characteristics of the resin film will be explained.

[0052] First, electromagnetic waves were irradiated onto a resin film, and the absorption rate for each wavelength of the electromagnetic waves was measured. In this measurement, the irradiation axis of the electromagnetic waves extends in the thickness direction of the resin film. The resin film in question is an example of the composition of resin film 5, and is made of modified polyethylene. The absorption rate curve C1 representing the measured absorption rate is shown in Figure 5A. The thickness of the resin film is 120 μm. The wavelength range of the electromagnetic waves is between 0.5 μm and 10.7 μm. The wavelength range of the electromagnetic waves also includes wavelength λ1, which is the fundamental wavelength of an infrared laser (IR (Infrared) laser), wavelength λ2, which is the same wavelength as the energy rays that can be irradiated by an infrared carbon heater, and wavelengths λ3 and λ4, which are the same wavelengths as a CO2 laser. Wavelength λ1 is 1.06 μm, wavelength λ2 is 2.00 μm, wavelength λ3 is 9.4 μm, and wavelength λ4 is 1.06 μm.

[0053] As shown in Figure 5A, the absorption rate of electromagnetic waves with wavelength λ1, which is the fundamental wavelength of an infrared laser, is approximately 4.7%. The absorption rate of electromagnetic waves with wavelength λ2 from an infrared carbon heater is approximately 8.0%. On the other hand, the absorption rate of electromagnetic waves with wavelength λ3 is approximately 23.1%. The absorption rate of electromagnetic waves with wavelength λ4 is approximately 15.7%. The absorption rates of electromagnetic waves with wavelengths λ3 and λ4 from a CO2 laser are both higher than those of electromagnetic waves with wavelengths λ1 and λ2.

[0054] <Integrated absorption amount with respect to depth from the incident surface of the resin film> Next, referring to Figures 5B to 5F, we will explain the results of calculating the integrated absorption amount with respect to the depth from the incident surface of the resin film by irradiating the resin film made of the modified polyethylene described above with each laser. Each laser is a CO2 laser having a wavelength λ3 or wavelength λ4 and an infrared laser having a wavelength λ1. Here, as shown in Figure 5B, the resin film 5 made of the modified polyethylene described above is replaced with a group of resin films 50 arranged in close contact with each other in the direction of laser irradiation, and the above calculation is performed. In other words, the laser L1 is irradiated onto the group of resin films 50, and the integrated absorption amount by the group of resin films 50 is calculated to determine the integrated absorption amount by the resin film 5.

[0055] The resin film group 50 includes resin films 51, 52, ..., 51+N, in other words, N resin films, where N is a natural number. The resin films 51, 52, ..., 51+N all have the same configuration, are made of the same material as resin film 5, and have the same thickness. The thickness direction of resin films 51, 52, ..., 51+N and the main surface direction of resin film 5 are the same as the irradiation direction of laser L1 (in this case, the X-axis direction).

[0056] The resin films 51, 52, ..., 51+N are in close contact with each other and are aligned in the thickness direction (in this case, the X-axis direction). Resin film 51 has a main surface 51a and a main surface 51b. The main surface 51a faces outward from the resin film group 50, and the main surface 51b faces the opposite side of the main surface 51a and is in close contact with the main surface 52a of resin film 52. Since the resin films 52, ..., 51+N are located inside the resin film group 50, the main surfaces 51b, ..., 51+Nb of resin films 51, ..., 51+N are in close contact with the main surfaces 52a, ..., 51+N+1a of the adjacent resin films 52, ..., 51+N+1. Therefore, no reflected light is generated on the main surfaces 52a, ..., 51+Na of resin films 52, ..., 51+N.

[0057] As shown in Figure 5C, the resin film group 50 is irradiated with laser L1. The laser L1 then splits into transmitted light L1a that passes through the resin film 51, absorbed light L1b that is absorbed by the resin film 51, and reflected light L1c that is reflected by the resin film 51. Next, the transmitted light L1a is incident on the resin film 52. The transmitted light L1a splits into transmitted light L2a that passes through the resin film 52, and absorbed light L1b that is absorbed by the resin film 52. Similarly, the transmitted light LNa splits into transmitted light L1+Na that passes through the resin film 51+N, and absorbed light L1+Nb that is absorbed by the resin film 51+N. In the resin films 53, ..., 51+N, the splitting of transmitted light and absorbed light is repeated, similar to the resin film 52. Multiple sheets of the resin film are stacked in close contact with each other. The laser L1 is irradiated in the thickness direction of the resin film and enters the main surface of the resin film.

[0058] This section describes a calculation method for determining the absorption and integrated absorption of a laser with wavelength λ3 as a function of depth from the incident surface of a resin film group 50. First, a laser with wavelength λ3 was irradiated onto resin film 51, and its reflectance, absorptance, and transmittance were measured. When the laser input was 100%, the reflectance was 8%, the absorptance was 23.1%, and the transmittance was 68.9%. Next, the absorptance and transmittance were calculated when the laser with wavelength λ3 was incident on resin film 52. When the laser input was 100%, the absorptance was 25.1% and the transmittance was 74.9%. From this, it can be calculated that when light that has passed through resin film 51 is incident on resin film 52, the absorptance is 17.3% and the transmittance is 51.6%. Using a similar calculation method, the absorptance and transmittance are calculated when the laser input is 100, and the light that has passed through resin film 51+k is incident on resin film 51+k+1. k is a natural number. The integrated absorption amount of a laser with wavelength λ3 was calculated with respect to the depth from the incident surface of the resin film group 50, and the calculation results are shown in Figure 5D.

[0059] Similarly, the integrated absorption of the resin film group 50 with respect to depth from the incident surface for a laser with wavelength λ4 was calculated, and the calculation results are shown in Figure 5E. The integrated absorption of the resin film group 50 with respect to depth from the incident surface for a laser with wavelength λ1 was calculated, and the calculation results are shown in Figure 5F. The resin film 51 was irradiated with a laser with wavelength λ4, and its reflectance, absorptance, and transmittance were measured. When the amount of incoming laser light was 100%, the reflectance was 8.6%, the absorptance was 15.7%, and the transmittance was 75.7%. The resin film 51 was also irradiated with a laser with wavelength λ1, and its reflectance, absorptance, and transmittance were measured. When the amount of incoming laser light was 100%, the reflectance was 7.9%, the absorptance was 4.7%, and the transmittance was 87.4%.

[0060] As shown in Figures 5D and 5E, when a laser with wavelength λ3 or λ4 is irradiated, the amount of absorption decreases as the depth from the incident surface increases, approaching 0 (zero), while the integrated amount of absorption increases, approaching 100.

[0061] As shown in Figure 5D, the cumulative absorption exceeds 90 at depths from 1.00 mm to 2.00 mm from the incident surface. In other words, the resin film 5 can absorb almost all of the laser light at depths from 1.00 mm to 2.00 mm from the incident surface. Therefore, when a laser with wavelength λ3 is irradiated, the welded portion A2 can be sufficiently formed at depths from 1.00 mm to 2.00 mm from the incident surface. As a result, the welded portion A2 is formed to a depth of 1.00 mm or more from the side surface of the laminate 100 and functions as a sealing portion.

[0062] As shown in Figure 5E, the cumulative absorption exceeds 80 at depths from 1.00 mm to 2.00 mm from the incident surface. In other words, the resin film 5 can absorb almost all of the laser light at depths from 1.00 mm to 2.00 mm from the incident surface. Therefore, when irradiated with a laser having a wavelength λ4, the welded portion A2 can be formed at depths from 1.00 mm to 2.00 mm from the incident surface.

[0063] As shown in Figure 5F, the integrated absorption is 70 or less at depths from 1.00 mm to 2.00 mm from the incident surface. The integrated absorption of laser light at depths from 1.00 mm to 2.00 mm from the incident surface when irradiated with a laser having wavelength λ1 is smaller than that when irradiated with a laser having wavelength λ3 or λ4. Therefore, when irradiated with a laser having wavelength λ1, the welded portion A2 is formed gradually at depths from 1.00 mm to 2.00 mm from the incident surface.

[0064] From the above, among the lasers having wavelengths λ3, λ4, and λ1, the laser with wavelength λ3 has the highest integrated absorption amount with respect to the depth from the main surface of the resin film group 50, thus enabling the stable formation of the welded portion A2. As described above, when a resin film 5 having a thickness of 120 μm is irradiated with light having a wavelength of λ3 (9.4 μm), the absorption rate of the resin film 5 is 23.1%. When a resin film 5 having a thickness of 120 μm is irradiated with light having a wavelength of λ3 (9.4 μm), and the optical axis of the light extends in the thickness direction of the resin film 5, the absorption rate of the resin film 5 is 10% or more and 30% or less, which allows for the stable formation of the welded portion A2.

[0065] <Modification 2> Next, with reference to Figure 6, a modified example 2 of the battery manufacturing method according to Embodiment 1 will be described. Modified example 2 of the battery manufacturing method according to Embodiment 1 has the same configuration as the battery manufacturing method according to Embodiment 1, except that step ST2 is different.

[0066] As shown in Figure 6, a galvanoscanner GS is used to irradiate the side surface of the laminate 100 with a CO2 laser (step ST32). In this step, similar to step ST2 shown in Figure 1, the CO2 laser is irradiated so that the laser spot moves along paths P1a, P2-P9, and P10a. The trajectories of the laser spot in paths P1a and P10a are the same as the trajectories of the laser spot in paths P1 and P10, respectively.

[0067] In process ST32, it is preferable to irradiate the laminate 100 with a CO2 laser in such a way that the amount of heat supplied to the laminate 100 in passes P1a and P10a is higher than the amount of heat supplied to the laminate 100 in the other passes P2 to P9.

[0068] Specifically, in process ST32, the CO2 laser should be irradiated such that the output of the CO2 laser in passes P1a and P10a is higher than the output of the CO2 laser in the other passes P2 to P9. More specifically, the output of the CO2 laser in passes P1a and P10a should be, for example, 140% to 160%, specifically 150%, of the output of the CO2 laser in the other passes P2 to P9.

[0069] Furthermore, in step ST32, it is preferable to irradiate the CO2 laser such that the scanning speed in passes P1a and P10a is smaller than the scanning speed in the other passes P2 to P9.

[0070] Furthermore, in step ST32, it is preferable to irradiate the CO2 laser so that the number of scans in passes P1a and P10a is greater than the number of scans in the other passes P2 to P9. Also, in step ST32, it is preferable to irradiate the CO2 laser so that the pitch in passes P1a and P10a is narrower than the pitch in the other passes P2 to P9.

[0071] Path P1a is closer to the pressure-restraining section PRU compared to the other paths P2 to P9. Similarly, path P10a is closer to the pressure-restraining section PRD compared to the other paths P2 to P9. The resin film 5 in paths P1a and P10a dissipates heat by passing through the pressure-restraining sections PRU and PRD, respectively. Also, the resin film 5 in paths P1a and P10a is located on the outside of the laminate 100 compared to the resin film 5 in the other paths P2 to P9. Therefore, the resin film 5 in paths P1a and P10a dissipates heat more easily and is less likely to be welded compared to the resin film 5 in the other paths P2 to P9. Accordingly, according to the modified version 2 of the battery manufacturing method of Embodiment 1 described above, the amount of heat supplied by CO2 laser irradiation in paths P1a and P10a can be increased to facilitate the welding of the resin film 5 in paths P1 and P10.

[0072] <Variation 3> Next, with reference to Figures 7A and 7B, a third modification of the battery manufacturing method according to Embodiment 1 will be described. The third modification of the battery manufacturing method according to Embodiment 1 has the same configuration as the battery manufacturing method according to Embodiment 1, except that step ST2 is different.

[0073] Using the galvanometer scanner GS shown in Figure 2D, a CO2 laser is irradiated onto the side surface of the laminate 100 as shown in Figure 7A (step ST42). Specifically, the CO2 laser is irradiated so that the laser light spot moves along paths P31 to P34. Paths P31 to P34 each extend along the interfaces between multiple resin films 5. By selectively irradiating the interfaces between multiple resin films 5 with the CO2 laser, the interfaces between the multiple resin films 5 are preferentially welded. As shown in Figure 7B, multiple welded portions A21 are formed at the interfaces between the multiple resin films 5. After step ST42 is performed, the battery 200 is formed. In the battery 200, the multiple welded portions A21 can suppress the passage of liquids and foreign matter between the multiple resin films 5. Since the volume of the multiple welded portions A21 is small compared to the volume of welded portion A2 shown in Figure 2E, the amount of CO2 laser irradiation required to form the multiple welded portions A21 is small. In other words, it is possible to improve energy efficiency.

[0074] <Example 2> Next, with reference to Figures 8A and 8B, Example 2, which implements the battery manufacturing method according to Embodiment 1, will be described.

[0075] A negative electrode active material layer is formed on one main surface of the current collector, and a positive electrode active material layer is formed on the other main surface of the current collector (step ST51). The current collector is a foil. The current collector functions as an electrode in a bipolar battery manufactured by this manufacturing method.

[0076] Next, multiple resin films are arranged to sandwich the outer circumference of the current collector obtained in step ST51, and the current collector and the resin films are welded together (step ST52).

[0077] Next, in step ST52, the current collector welded to the resin film and the separator are laminated together to obtain a laminate (step ST53).

[0078] Finally, the resin film region of the laminate 100B shown in Figure 8A is pressurized and restrained, and a CO2 laser is irradiated onto the surface of the resin film using the following workpiece conditions, laser oscillation conditions, and laser trajectory conditions to weld the resin film (step ST54).

[0079] The workpiece conditions were as follows: the resin film material was modified polyethylene, the resin film thickness was 19.2 mm, and the number of layers of resin film was 91. The main surface of the resin film was a square with a side length of 140 mm. The laser oscillation conditions were: laser type was CO2 pulsed laser, wavelength 9400 μm, output 215 W, frequency 50 kHz, duty cycle 45%, spot size 0.8 mm. The laser trajectory conditions were as shown in Figure 8B: scanning distance 140 mm, pitch 0.8 mm, number of passes 20. The laser trajectory conditions were: number of repetitions 50, scanning speed 6000 mm / sec. The processing time was 30.753 seconds.

[0080] In process ST54, the pressure-restraining parts PRU2 and PRD2 shown in Figure 8A were used. The pressure-restraining parts PRU2 and PRD2 are a pair of plate-like bodies made of bakelite. The four corners of the pressure-restraining parts PRU2 and PRD2 are fastened with bolts (not shown). The main surface of the pressure-restraining parts PRU2 and PRD2 is a roughly rectangular shape measuring 130 mm × 195 mm. The thickness of the pressure-restraining parts PRU2 and PRD2 is 20 mm. The ends of the pressure-restraining parts PRU2 and PRD2 are covered with aluminum tape 71. Each glass cloth 72 covers the boundary between the pressure-restraining part PRU2 and the aluminum tape 71, and the boundary between the pressure-restraining part PRD2 and the aluminum tape 71. The end of the laminate 100B is located at the boundary between the glass cloth 72 and the aluminum tape 71. The pressure-restraining parts PRU2 and PRD2 were used to pressurize and restrain the laminate 100B and the dummy 800. Since the dummy 800 has almost the same shape and rigidity as the laminate 100B, it ensures that the pressure restraint sections PRU2 and PRD2 are approximately parallel to each other.

[0081] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. Furthermore, the present invention may be implemented by combining the above embodiments or examples thereof as appropriate. [Explanation of symbols]

[0082] 1 Positive electrode, 2 Negative electrode, 3 Separator, 4 Foil, 5 Resin film, 5a Aperture, 6 Components, 10 Electrode body, 50 Resin film group, 51-54, 51+N Resin film, 51a-54a, 54b-54b, 51+Na, 51+Nb Main surface, 71 Aluminum tape, 72 Glass cloth, 100, 100A, 100B Laminate, 200 Battery, A1 Edge, A2, A21 Welded part, AU1 Unit location, AU2 Depth, AU3 Surface, GS Galvanometer scanner, L1 Laser, L1a, L2a, LNa, L1+Na Transmitted light, L1b, L2b, L1+Nb Absorbed light, L1c Reflected light, P1-P10, P1a, P10a, P21-P28, P31-P34 Path, PRD, PRD2, PRU, PRU2 Pressurized restraint section

Claims

1. It comprises multiple electrode bodies and a sealing portion, The plurality of electrode bodies are stacked, The sealing portion is a welding portion that seals the gaps between the ends of the plurality of electrode bodies, in a method for manufacturing a battery. CO2 is supplied to a plurality of sealing members arranged between the ends of the plurality of electrode bodies. ２ The process includes a step of heating and welding the plurality of sealing members by irradiating them with a laser to form the welded portion, In the process of forming the welded portion, the CO ２ Using a galvanometer scanner, the laser beam spot from the laser moves back and forth at a predetermined pitch on one side of the stacked plurality of electrode bodies in a direction along the interface between the stacked plurality of sealing members, and the laser beam spot with a wavelength that the plurality of sealing members can absorb is directed to the plurality of sealing members positioned between the ends of the plurality of electrode bodies. ２ A method of manufacturing batteries that involves irradiating them with a laser.

2. The aforementioned CO ２ The laser output is between 100W and 300W. The aforementioned CO ２ The laser scanning speed is between 4000 mm / sec and 6000 mm / sec. A method for manufacturing a battery according to claim 1.

3. The plurality of sealing members include polyolefin, A method for manufacturing a battery according to claim 1 or 2.

4. The plurality of sealing members are films having a thickness of 120 μm, and when light having a wavelength of 9.4 μm is irradiated onto the film, and the optical axis of the light extends in the thickness direction of the film, the absorption rate of the film in which the light is absorbed is 10% or more and 30% or less. A method for manufacturing a battery according to claim 1 or 2.

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