Method for manufacturing a power storage device and power storage device

Abstract

To provide a power storage device manufacturing method and a power storage device that have the reliability of dimensional accuracy.SOLUTION: A laser beam L that is used in a power storage device manufacturing method disclosed herein is a multi-point laser beam including a first laser beam L1 composed of at least one or more beams with which an aperture sealing plate long side and an aperture sealing plate short side 18a are irradiated, and a second laser beam L2 composed of at least one or more beams with which an opening long side and an opening short side 15a are irradiated. When a region composed of the opening long side and the aperture sealing plate long side is defined as a long side region and a region composed of the opening short side 15a and the aperture sealing plate short side 18a is defined as a short side region 11a, the energy of the laser beam L with which the short side region 11a is irradiated is smaller than the energy of the laser beam L with which the long side region is irradiated, and the energy of the second laser beam L2 with which the short side region 11a is irradiated is smaller than the energy of the first laser beam L1 with which the short side region 11a is irradiated.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a power storage device and a power storage device.

Background Art

[0002] In recent years, power storage devices such as lithium-ion secondary batteries have been suitably used for portable power sources such as personal computers and mobile terminals, and power sources for driving vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). Conventionally, a power storage device is known that includes an exterior body having a rectangular bottom, an opening facing the bottom, a pair of long side walls extending from the long side of the bottom and facing each other, and a pair of short side walls extending from the short side of the bottom and facing each other, and a sealing plate that seals the opening, and a molten solidified portion is provided at a fitting portion between the exterior body and the sealing plate. For example, in Patent Document 1, when laser-welding a battery case (exterior body) and a lid member (sealing plate), a first laser irradiation step of irradiating laser light to a boundary portion between the battery case and the lid member, and a second laser irradiation step of irradiating laser light to the battery case and the lid member on the front side in the progress direction of laser welding compared to the irradiation position of the laser light in the first laser irradiation step are disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a conventional power storage device, the dimensions of the power storage device become unstable due to the protrusion of the molten and solidified part outward from the short side wall. As the power storage device becomes more widespread, stability of dimensional accuracy is required, and high reliability including stability of welding quality and high energy is demanded. Therefore, the inventor considers it desirable to suppress the protrusion of the molten and solidified part of the power storage device outward from the short side wall.

[0005] The technology disclosed herein has been made in view of the above circumstances, and its object is to provide a method for manufacturing a power storage device and a power storage device having reliability of dimensional accuracy by suppressing the protrusion of the molten and solidified part outward from the short side wall.

Means for Solving the Problems

[0006] The technology disclosed herein includes an electrode body having electrodes, a rectangular bottom, a pair of short side walls extending from the short sides of the bottom and facing each other, a pair of long side walls extending from the long sides of the bottom and facing each other, an opening facing the bottom, a pair of opening long side portions corresponding to the ends of the long side walls among the peripheral edges of the opening, and a pair of opening short side portions corresponding to the ends of the short side walls. It also includes an exterior body for housing the electrode body, a substantially rectangular sealing plate having a pair of sealing plate long side portions and a pair of sealing plate short side portions for sealing the opening of the exterior body, and a terminal attached to the sealing plate and electrically connected to the electrode body. A method for manufacturing a power storage device includes a sealing plate fitting step of housing the electrode body in the exterior body and fitting the sealing plate into the opening of the exterior body, and a laser welding step of scanning the laser beam L over the entire circumference of the sealing plate and the opening to laser-weld the sealing plate and the exterior body. Here, in the laser welding step, the laser beam L is a multi-point laser beam including a first laser beam L1 composed of at least one or more beams irradiating the sealing plate long side portion and the sealing plate short side portion, and a second laser beam L2 composed of at least one or more beams irradiating the opening long side portion and the opening short side portion. When the region composed of the opening long side portion and the sealing plate long side portion is defined as the long side region and the region composed of the opening short side portion and the sealing plate short side portion is defined as the short side region, the energy of the laser beam L irradiating the short side region is smaller than the energy of the laser beam L irradiating the long side region, and the energy of the second laser beam L2 irradiating the short side region is smaller than the energy of the first laser beam L1 irradiating the short side region.

[0007] According to such a configuration, when forming a molten and solidified portion by the laser beam L, the molten portion in the short side region is smaller than the molten portion in the long side region. Also, for the short side region, the molten portion of the opening short side portion is smaller than the molten portion of the sealing plate short side portion. As a result, for the short side region, melting of the opening short side portion (short side wall) can be suppressed compared to the sealing plate short side portion, and formation of the molten and solidified portion outside the short side wall of the exterior body can be suppressed. Therefore, a power storage device with reliable dimensional accuracy can be manufactured.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

[0009] Hereinafter, embodiments according to the technology disclosed herein will be described with reference to the drawings. Matters not mentioned in this specification and necessary for the implementation of the technology disclosed herein can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common general knowledge in the relevant field. In the following drawings, members and parts having the same function are denoted by the same reference numerals and will be described. Also, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships. In this specification, a numerical range expressed as "A to B" includes A and B, and also includes the meaning of "preferably greater than A" and "preferably less than B".

[0010] As used herein, the "power storage device" refers to a device that can perform charging and discharging. Power storage devices generally include batteries such as lithium-ion batteries and lithium secondary batteries, as well as lithium polymer batteries, lithium-ion capacitors, and the like. A secondary battery generally refers to a battery that can be repeatedly charged and discharged as the charge carrier moves between the positive and negative electrodes. Here, as one form of the power storage device, a lithium-ion secondary battery is exemplified.

[0011] <Power Storage Device 100> FIG. 1 is a perspective view schematically showing the power storage device 100. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. FIG. 3 is a plan view schematically showing the exterior body 12 and the sealing plate 18. In FIGS. 2 and 3, the exterior body 12 and the sealing plate 18 are before being welded (before the fusion solidification part 50 is formed). In the following description, the reference signs L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, upper, and lower, respectively. Also, the reference sign X in the drawings indicates the short side direction of the power storage device 100, the reference sign Y indicates the long side direction of the power storage device 100, and the reference sign Z indicates the vertical direction. However, these are merely directions for convenience of explanation and do not limit the installation form of the power storage device 100 in any way.

[0012] As shown in FIGS. 1 and 2, the power storage device 100 includes a case 1, an electrode body 20, a positive electrode terminal 6, a negative electrode terminal 8, a positive electrode current collecting member 35, and a negative electrode current collecting member 45. Although not shown in the drawings, the power storage device 100 further includes an electrolytic solution here. The configuration of the power storage device 100 may be the same as that of the prior art. The power storage device 100 is preferably a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

[0013] The case 1 is a housing that houses the electrode body 20. As shown in FIGS. 1 and 2, the case 1 includes an exterior body 12 having an opening 15 and a sealing plate 18 that seals the opening 15. The exterior body 12 and the sealing plate 18 have sizes corresponding to the number of electrode bodies 20 to be accommodated (one or more), size, etc. The case 1 is preferably made of metal, and more preferably made of aluminum or an aluminum alloy mainly composed of aluminum. Here, the case 1 is made of aluminum. As shown in FIG. 1, the case 1 has a flat and bottomed substantially rectangular parallelepiped shape (square shape) here.

[0014] As shown in FIGS. 1 and 2, the outer package 12 is a bottomed and substantially rectangular parallelepiped container having an opening 15 on one side surface (here, the upper surface). As shown in FIG. 1, the outer package 12 includes a substantially rectangular bottom portion 12d having a pair of short sides and a pair of long sides, a pair of short side walls 12a and 12b extending upward from the short sides of the bottom portion 12d and facing each other, and a pair of long side walls 12e and 12f extending upward from the long sides of the bottom portion 12d and facing each other. In this specification, the term "substantially rectangular" includes, in addition to a perfect rectangular shape (rectangular shape), for example, a shape in which the corners connecting the long side and the short side of the rectangular shape are R-shaped, a shape having a notch at the corner, and the like.

[0015] An opening 15 surrounded by a pair of short side walls 12a and 12b and a pair of long side walls 12e and 12f is formed on one side surface of the outer package 12. As shown in FIG. 2, the bottom portion 12d faces the opening 15. The opening 15 includes a pair of opening long side portions 15e and 15f corresponding to the ends of the long side walls 12e and 12f among the peripheral edges of the opening 15, and a pair of opening short side portions 15a and 15b corresponding to the ends of the short side walls 12a and 12b (the upper side in FIG. 2).

[0016] As shown in FIGS. 1 and 2, the sealing plate 18 is a member for sealing the opening 15 of the outer package 12. Here, the sealing plate 18 is a plate-like member having a substantially rectangular plane. As shown in FIG. 3, the sealing plate 18 includes a pair of sealing plate short side portions 18a and 18b and a pair of sealing plate long side portions 18e and 18f. As shown in FIG. 2, a liquid injection hole 71, a gas discharge valve 73, and terminal lead-out holes 74 and 75 are provided in the sealing plate 18. The sealing plate 18 faces the bottom portion 12d of the outer package 12.

[0017] As shown in FIG. 3, the fitting portion 11 is formed by arranging (fitting) the outer peripheral surface of the sealing plate 18 and the inner surface (opening portion 15) of the exterior body 12 to face each other. Specifically, the short side portion 18a of the sealing plate faces the short side portion 15a of the opening, the short side portion 18b of the sealing plate faces the short side portion 15b of the opening, the long side portion 18e of the sealing plate faces the long side portion 15e of the opening, and the long side portion 18f of the sealing plate faces the long side portion 15f of the opening. Here, the upper ends (the upper end portions in FIG. 2) of the sealing plate 18 and the exterior body 12 are flush in a plan view. As shown in FIG. 3, the fitting portion 11 includes short side regions 11a, 11b and long side regions 11e, 11f. The short side region 11a is a region formed by the short side portion 15a of the opening and the short side portion 18a of the sealing plate, and the short side region 11b is a region formed by the short side portion 15b of the opening and the short side portion 18b of the sealing plate. The long side region 11e is a region formed by the long side portion 15e of the opening and the long side portion 18e of the sealing plate, and the long side region 11f is a region formed by the long side portion 15f of the opening and the long side portion 18f of the sealing plate. Also, as shown in FIG. 3, here the fitting portion 11 has R portions 11g, 11h, 11i, 11j provided between the short side regions 11a, 11b and the long side regions 11e, 11f. However, the R portions 11g, 11h, 11i, 11j are not essential.

[0018] The liquid injection hole 71 is a through hole for injecting the electrolytic solution into the case 1 after assembling the sealing plate 18 to the exterior body 12. Here, the liquid injection hole 71 is sealed by a sealing member 72 after injecting the electrolytic solution. The gas discharge valve 73 is a thin-walled portion configured to break when the pressure in the case 1 reaches a predetermined value or more and discharge the gas in the case 1 to the outside.

[0019] As the electrolytic solution, those conventionally known and used can be used without particular limitation. As an example, a non-aqueous electrolytic solution in which a supporting salt (electrolyte salt) is dissolved in a non-aqueous solvent (organic solvent) is preferably used. As an example of the non-aqueous solvent, carbonate solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate can be mentioned. As an example of the supporting salt, fluorine-containing lithium salts such as LiPF6 can be mentioned. The electrolytic solution may contain additives as necessary.

[0020] The positive electrode terminal 6 is attached to one end of the sealing plate 18 in the long side direction Y (the left end in FIG. 2). The negative electrode terminal 8 is attached to the other end of the sealing plate 18 in the long side direction Y (the right end in FIG. 2). As shown in FIG. 2, the positive electrode terminal 6 and the negative electrode terminal 8 are inserted through the terminal lead-out holes 74 and 75 and exposed on the outer surface of the sealing plate 18. As shown in FIG. 2, the positive electrode terminal 6 is electrically connected to the positive electrode 3 of the electrode body 20 through the positive electrode current collector member 35 inside the outer package 12. The negative electrode terminal 8 is electrically connected to the negative electrode 4 of the electrode body 20 through the negative electrode current collector member 45 inside the outer package 12. The positive electrode terminal 6 and the negative electrode terminal 8 are insulated from the sealing plate 18 by the gasket 76 and the insulator 78. Also, a current interruption mechanism (CID) may be installed between the positive electrode terminal 6 and the positive electrode current collector member 35 or between the negative electrode terminal 8 and the negative electrode current collector member 45.

[0021] The positive electrode terminal 6 is preferably made of metal, more preferably made of, for example, aluminum or an aluminum alloy. The negative electrode terminal 8 is preferably made of metal, more preferably made of, for example, copper or a copper alloy. The negative electrode terminal 8 may be configured by joining and integrating two conductive members. For example, the portion connected to the negative electrode current collector member 45 may be made of copper or a copper alloy, and the portion exposed on the outer surface of the sealing plate 18 may be made of aluminum or an aluminum alloy.

[0022] For the gasket 76 and the insulator 78, it is preferable to use a material having excellent chemical resistance and weather resistance. The gasket 76 and the insulator 78 may be made of a resin material having electrical insulation and capable of elastic deformation, for example, a fluorinated resin such as perfluoroalkoxy fluororesin (PFA), polyphenylene sulfide resin (PPS), aliphatic polyamide, or the like.

[0023] Here, the positive electrode terminal 6 is electrically connected to the plate-shaped positive electrode external conductive member 36 outside the case 1. Similarly, the negative electrode terminal 8 is electrically connected to the plate-shaped negative electrode external conductive member 46 outside the case 1. The positive electrode external conductive member 36 and the negative electrode external conductive member 46 are connected to other power storage devices or external devices via an external connection member such as a bus bar. The positive electrode external conductive member 36 and the negative electrode external conductive member 46 are preferably made of a metal excellent in conductivity such as aluminum, aluminum alloy, copper, copper alloy, etc. However, the positive electrode external conductive member 36 and the negative electrode external conductive member 46 are not essential and can be omitted in other embodiments.

[0024] The electrode body 20 may be the same as the conventional one and is not particularly limited. As shown in FIG. 2, the electrode body 20 has a positive electrode 3 and a negative electrode 4. Here, the electrode body 20 is a flat wound electrode body in which a strip-shaped positive electrode 3 and a strip-shaped negative electrode 4 are laminated in an insulated state via a strip-shaped separator 7 and wound around a winding axis. However, the electrode body 20 may be a laminated electrode body in which a rectangular (typically rectangular) positive electrode 3 and a rectangular (typically rectangular) negative electrode 4 are stacked in an insulated state. Also, the number of electrode bodies 20 disposed inside one exterior body 12 is not particularly limited and may be two or more (plural). Note that the positive electrode 3 and the negative electrode 4 are examples of the "electrode" in the technology disclosed herein.

[0025] As shown in FIG. 2, the positive electrode 3 has a positive electrode current collector 30 and a positive electrode active material layer 31 fixed on the positive electrode current collector 30. The positive electrode current collector 30 is made of a conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, etc. The positive electrode active material layer 31 is a layer containing a positive electrode active material (for example, a lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide) capable of reversibly occluding and releasing charge carriers.

[0026] The negative electrode 4 includes a negative electrode current collector 40 and a negative electrode active material layer 41 fixed on the negative electrode current collector 40. The negative electrode current collector 40 is made of a conductive metal such as copper, copper alloy, nickel, stainless steel, etc. The negative electrode active material layer 41 is a layer containing a negative electrode active material (such as a carbon material like graphite) that can reversibly occlude and release charge carriers.

[0027] The separator 7 is a member that insulates the positive electrode active material layer 31 of the positive electrode 3 and the negative electrode active material layer 41 of the negative electrode 4. As the separator 7, for example, a porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable. Note that a heat resistance layer (HRL) containing an inorganic filler may be provided on the surface of the separator 7.

[0028] As shown in FIG. 2, at the left end portion in the long side direction Y of the electrode body 20, a part of the positive electrode current collector 30 where the positive electrode active material layer 31 is not formed (positive electrode current collector exposed portion) protrudes from the laminated portion. A positive electrode current collecting member 35 is attached to the positive electrode current collector exposed portion. The positive electrode current collecting member 35 may be made of the same metal material as the positive electrode current collector 30, for example, a conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, etc. Also, at the right end portion in the long side direction Y of the electrode body 20, a part of the negative electrode current collector 40 where the negative electrode active material layer 41 is not formed (negative electrode current collector exposed portion) protrudes from the laminated portion. A negative electrode current collecting member 45 is attached to the negative electrode current collector exposed portion. The material (metal type) of the negative electrode current collecting member 45 may be different from that of the positive electrode current collecting member 35. The negative electrode current collecting member 45 may be made of the same metal type as the negative electrode current collector 40, for example, a conductive metal such as copper, copper alloy, nickel, stainless steel, etc.

[0029] <Manufacturing Method of the Power Storage Device 100> FIG. 4 is a flowchart showing a method for manufacturing the power storage device 100 according to an embodiment. The power storage device 100 disclosed herein can be manufactured by a manufacturing method including a sealing plate fitting step S10 and a laser welding step S20, and is characterized by performing the laser welding step S20. Further, in the manufacturing method of the power storage device 100 disclosed herein, in addition to the above steps, other steps may be further included at any stage, and the other manufacturing processes may be the same as those in the prior art.

[0030] (Sealing plate fitting step S10) In the sealing plate fitting step S10, the electrode body 20 is housed in the exterior body 12, and the sealing plate 18 is fitted into the opening 15 of the exterior body 12. First, as shown in FIG. 2, the positive electrode terminal 6 and the negative electrode terminal 8 are inserted through the terminal lead-out holes 74 and 75 via the gasket 76 and the insulator 78, and are attached so that one end is exposed on the outer surface of the sealing plate 18. The other end of the positive electrode terminal 6 is electrically connected to the positive electrode 3 of the electrode body 20 via the positive electrode current collecting member 35. On the other hand, the other end of the negative electrode terminal 8 is electrically connected to the negative electrode 4 of the electrode body 20 via the negative electrode current collecting member 45. Then, the electrode body 20 is housed in the exterior body 12, and the sealing plate 18 is fitted into the opening 15 of the exterior body 12. Thereby, the upper end portion of the exterior body 12 and the sealing plate 18 are flush. Further, the outer peripheral surface of the sealing plate 18 and the inner surface of the exterior body 12 (opening 15) face each other.

[0031] (Laser welding step S20) In the laser welding step S20, after the sealing plate fitting step S10, the laser beam L is scanned over the entire circumference of the sealing plate 18 and the opening 15 of the case 1, thereby laser-welding the sealing plate 18 and the exterior body 12. In the present embodiment, as shown by the arrow in FIG. 3, starting from the starting point LS within the short side region 11a along the fitting portion 11, the laser beam L is scanned through the short side region 11a, the R portion 11g, the long side region 11e, the R portion 11h, the short side region 11b, the R portion 11i, the long side region 11f, and the R portion 11j in this order, passes through the starting point LS within the short side region 11a, and is scanned to the end point LE within the short side region 11a. As a result, the fusion-solidified portion 50 (see FIG. 13) is formed, and the sealing plate 18 and the exterior body 12 are joined. By the laser welding step S20, the case 1 is hermetically sealed.

[0032] FIG. 19 is a longitudinal sectional view showing the vicinity of the fusion-solidified portion 50 according to the conventional example. Incidentally, conventionally, in the laser welding as described above, a part of the sealing plate 18 and the exterior body 12 (shown by a virtual line) is melted by the irradiation of the laser beam, and the fusion-solidified portion 50 is formed by the solidification of such a melted portion. The shape of the fusion-solidified portion 50 is determined by, for example, the flow of the molten metal and the influence of the surface tension. More specifically, the fusion-solidified portion 50 is formed by solidifying in a shape swelled by the surface tension of the molten metal. Therefore, as shown in FIG. 19, there is a possibility that a part of the fusion-solidified portion 50 protrudes outward from the short side walls 12a and 12b of the exterior body 12. Due to such protrusion of the fusion-solidified portion 50, there is a variation in the size of the power storage device 100 (case 1) in the long side direction Y. Therefore, the inventor intends to suppress the protrusion of the fusion-solidified portion 50 outside the short side walls 12a and 12b of the exterior body 12. In addition, "formed (protruding) outside the exterior body" in this specification means that at least a part of the fusion-solidified portion 50 protrudes in the long side direction Y from the exterior body 12. The protrusion of at least a part of the fusion-solidified portion 50 in the short side direction X and the vertical direction Z is not included in "protruding outward".

[0033] The technology disclosed herein has been created in view of the above-described problems. The technology disclosed herein is characterized by the laser beam L used in the laser welding step S20. The laser beam L includes a long-side region irradiation laser beam La that irradiates the long-side regions 11e and 11f, and a short-side region irradiation laser beam Lb that irradiates the short-side regions 11a and 11b (see FIGS. 5 and 6). The laser beam L (the long-side region irradiation laser beam La and the short-side region irradiation laser beam Lb) includes a first laser beam L1 composed of at least one or more beams that irradiate the sealing plate 18 (the long-side portions 18e and 18f of the sealing plate and the short-side portions 18a and 18b of the sealing plate), and a second laser beam L2 composed of at least one or more beams that irradiate the opening 15 (the long-side portions 15e and 15f of the opening and the short-side portions 15a and 15b of the opening). And, the energy of the laser beam L (the short-side region irradiation laser beam Lb) that irradiates the short-side regions 11a and 11b is made smaller than the energy of the laser beam L (the long-side region irradiation laser beam La) that irradiates the long-side regions 11e and 11f, and the energy of the second laser beam L2 that irradiates the short-side regions 11a and 11b (the short-side portions 15a and 15b of the opening) is made smaller than the energy of the first laser beam L1 that irradiates the short-side regions 11a and 11b (the short-side portion 18b of the sealing plate). Note that the long-side region irradiation laser beam La is an example of the "laser beam L that irradiates the long-side region" in the technology disclosed herein, and the short-side region irradiation laser beam Lb is an example of the "laser beam L that irradiates the short-side region" in the technology disclosed herein.

[0034] Hereinafter, examples will be given to explain the technology disclosed herein, but the present invention is not limited to such examples. FIG. 5 is a plan view schematically showing the long-side region irradiation laser beam La according to one example. FIG. 6 is a plan view schematically showing the short-side region irradiation laser beam Lb according to one example. For FIGS. 5 and 6, the traveling directions of the long-side region irradiation laser beam La and the short-side region irradiation laser beam Lb are indicated by white arrows. As shown in FIGS. 5 and 6, here, the laser beam L (the long-side region irradiation laser beam La and the short-side region irradiation laser beam Lb) has a first laser beam L1, a second laser beam L2, and a center beam 90 that irradiates the boundary between the opening 15 and the sealing plate 18. Note that the center beam 90 may be a single-point beam or a multi-point beam composed of a plurality of points close to each other. Here, the center beam 90 is a single point. Here, the first laser beam L1 and the second laser beam L2 are arranged around the center beam 90. Here, the energy per point of the peripheral beams 91 to 98 is the same in the short-side region irradiation laser beam Lb and the long-side region irradiation laser beam La. Also, the energy per point of the center beam 90 is the same in the short-side region irradiation laser beam Lb and the long-side region irradiation laser beam La.

[0035] As shown in FIG. 5, here, the long-side region irradiation laser beam La includes a central beam 90, a first laser beam L1 composed of four peripheral beams 91 to 94, and a second laser beam L2 composed of four peripheral beams 95 to 98. As shown in FIG. 5, the long-side region irradiation laser beam La is arranged in a substantially X shape in plan view. On the other hand, as shown in FIG. 6, compared with the long-side region irradiation laser beam La, the short-side region irradiation laser beam Lb has the same arrangement pattern of the peripheral beams 91 to 94 of the first laser beam L1, but has a pattern in which the peripheral beams 95 and 98 of the second laser beam L2 are missing. That is, the energy of the short-side region irradiation laser beam Lb (here, the sum of the energies of the central beam 90 and the peripheral beams 91 to 94, 96, and 97) is smaller than the energy of the long-side region irradiation laser beam La (the sum of the energies of the central beam 90 and the peripheral beams 91 to 98). Also, as shown in FIG. 6, in the short-side region irradiation laser beam Lb, the number of beam points of the second laser beam L2 (two points) is smaller than the number of beam points of the first laser beam L1 (four points). That is, among the short-side region irradiation laser beam Lb, the energy of the second laser beam L2 that irradiates the short-side regions 11a and 11b (the open short-side portions 15a and 15b) is smaller than the energy of the first laser beam L1 that irradiates the short-side regions 11a and 11b (the sealing plate short-side portions 18a and 18b).

[0036] FIG. 7 is a plan view schematically showing a state in which the long-side region irradiation laser beam La is irradiated onto the long-side region 11e according to an embodiment. FIG. 8 is a plan view schematically showing a state in which the long-side region irradiation laser beam La is irradiated onto the long-side region 11f according to an embodiment. FIG. 9 is a plan view schematically showing a state in which the short-side region irradiation laser beam Lb is irradiated onto the short-side region 11a according to an embodiment. FIG. 10 is a plan view schematically showing a state in which the short-side region irradiation laser beam Lb is irradiated onto the short-side region 11b according to an embodiment. For FIGS. 7 to 10, the traveling directions of the long-side region irradiation laser beam La and the short-side region irradiation laser beam Lb are indicated by white arrows. FIG. 11 is a longitudinal sectional view schematically showing a state in which the long-side region irradiation laser beam La is irradiated onto the long-side region 11e according to an embodiment. FIG. 12 is a longitudinal sectional view schematically showing a state in which the short-side region irradiation laser beam Lb is irradiated onto the short-side region 11a according to an embodiment. FIG. 13 is a longitudinal sectional view schematically showing the formation of the melting and solidifying portion 50 in the short-side region 11a according to an embodiment.

[0037] As shown in FIG. 7, among the long-side region irradiation laser beams La arranged in the long-side region 11e, the central beam 90 is irradiated onto the boundary portion between the opening long-side portion 15e and the sealing plate long-side portion 18e. The peripheral beams 91 to 94 arranged at one end in the short-side direction X (the front side in FIG. 7) are irradiated onto the sealing plate long-side portion 18e as the first laser beam L1. Then, the peripheral beams 95 to 98 arranged at the other end in the short-side direction X (the rear side in FIG. 7) are irradiated onto the opening long-side portion 15e as the second laser beam L2. Similarly, as shown in FIG. 8, among the long-side region irradiation laser beams La arranged in the long-side region 11f, the central beam 90 is irradiated onto the boundary portion between the opening long-side portion 15f and the sealing plate long-side portion 18f. The peripheral beams 91 to 94 arranged at one end in the short-side direction X (the rear side in FIG. 8) are irradiated onto the sealing plate long-side portion 18f as the first laser beam L1. Then, the peripheral beams 95 to 98 arranged at the other end in the short-side direction X (the front side in FIG. 8) are irradiated onto the opening long-side portion 15f as the second laser beam L2.

[0038] As shown in Fig. 9, among the short-side region irradiation laser beams Lb arranged in the short-side region 11a, the central beam 90 is irradiated onto the boundary between the open short-side portion 15a and the sealing plate short-side portion 18a. The peripheral beams 91 to 94 arranged at one end in the long-side direction Y (the right side in Fig. 9) are irradiated onto the sealing plate short-side portion 18a as the first laser beam L1. On the other hand, the peripheral beams 96, 97 arranged at the other end in the long-side direction Y (the left side in Fig. 9) are irradiated onto the open short-side portion 15a as the second laser beam L2. As shown in Fig. 10, among the short-side region irradiation laser beams Lb arranged in the short-side region 11b, the central beam 90 is irradiated onto the boundary between the open short-side portion 15b and the sealing plate short-side portion 18b. The peripheral beams 91 to 94 arranged at one end in the long-side direction Y (the left side in Fig. 10) are irradiated onto the sealing plate short-side portion 18b as the first laser beam L1. On the other hand, the peripheral beams 96, 97 arranged at the other end in the long-side direction Y (the right side in Fig. 10) are irradiated onto the open short-side portion 15b as the second laser beam L2.

[0039] At this time, as shown in FIGS. 11 and 12, the energy of the short-side region irradiation laser beam Lb that irradiates the short-side region 11a is smaller than that of the long-side region irradiation laser beam La that irradiates the long-side region 11e. Further, as shown in FIG. 12, among the short-side region irradiation laser beams Lb, the energy of the second laser beam L2 that irradiates the opening short-side portion 15a is smaller than the energy of the first laser beam L1 that irradiates the sealing plate short-side portion 18a. Therefore, the melted portion 51 of the short-side region 11a is smaller than the melted portion 51 of the long-side region 11e. Also, for the short-side region 11a, the melted portion 51 of the opening short-side portion 15a is smaller than the melted portion 51 of the sealing plate short-side portion 18a. As a result, as shown in FIG. 13, for the short-side region 11a, melting of the opening short-side portion 15a (short side wall 12a) is suppressed compared to the sealing plate short-side portion 18a, and it is possible to suppress the formation of the melt-solidified portion 50 outside the short side wall 12a of the exterior body 12. Here, the short-side region 11a and the long-side region 11e are described as examples, but for the short-side region 11b and the long-side region 11f as well, the same operations as those of the short-side region 11a and the long-side region 11e can be obtained. Therefore, similarly for the short-side region 11b, by irradiating the first laser beam L1 of the short-side region irradiation laser beam Lb to the sealing plate short-side portion 18b and the second laser beam L2 to the opening short-side portion 15b, melting of the opening short-side portion 15b (short side wall 12b) can be suppressed, and it is possible to suppress the formation of the melt-solidified portion 50 outside the short side wall 12b of the exterior body 12. As a result, it is possible to suppress the protrusion of the melt-solidified portion 50 outside the short side walls 12a and 12b of the exterior body 12. Therefore, in the long-side direction Y, it is possible to provide the power storage device 100 with improved dimensional accuracy of Case 1.

[0040] Also, in some preferred embodiments, as shown in FIGS. 5 and 6, the number of beam points (4 points) of the first laser beam L1 in the short-side region irradiation laser beam Lb is the same as the number of beam points (4 points) of the first laser beam L1 in the long-side region irradiation laser beam La, and the number of beam points (2 points) of the second laser beam L2 in the short-side region irradiation laser beam Lb is less than the number of beam points (4 points) of the second laser beam L2 in the long-side region irradiation laser beam La. As a result, it is possible to more preferably suppress the protrusion of the melt-solidified portion 50 outside the short side walls 12a and 12b of the exterior body 12.

[0041] In the short side regions 11a and 11b, the energy of the laser beam L (the short side region irradiation laser beam Lb) (the total energy of the first laser beam L1 and the second laser beam. Further, when the central beam 90 is included, the total energy of the first laser beam L1, the second laser beam, and the central beam 90.) is preferably 1000 W or more, and more preferably 1500 W or more. On the other hand, from the viewpoint of suppressing the protrusion of the short side walls 12a and 12b of the melting and solidifying portion 50 outward, it is preferably 4000 W or less, and more preferably 3000 W or less. Further, in the short side regions 11a and 11b, the ratio of the energy of the first laser beam L1 to the energy of the second laser beam L2 is preferably 5:1 to 1.25:1, and more preferably 5:1 to 2:1. When the energy ratio is smaller than the above range, it is not possible to suitably suppress the protrusion of the melting and solidifying portion. When the energy ratio is larger than the above range, welding defects may occur due to insufficient welding energy at the opening 15, which is not preferable.

[0042] As shown in FIG. 3, the scanning path of the laser beam L is counterclockwise from the start point LS to the end point LE here, but it is not limited thereto. As long as the annular melting and solidifying portion 50 is formed and the case 1 can be sealed, the start point LS and the end point LE of the scanning path of the laser beam L may be changed. Further, the scanning path of the laser beam L may be clockwise or counterclockwise.

[0043] The method for generating the laser beam L used in the laser welding step S20 may be a bundle composed of a plurality of laser sources irradiated from a plurality of laser devices, or may use pattern formation by a dynamic beam laser, or may branch one laser source using a diffractive optical element (DOE) or the like. Among them, according to the transmission diffraction using a diffractive optical element, the laser beam L according to the present embodiment can be easily generated. For this reason, the generation of the laser beam L by transmission diffraction using a diffractive optical element (DOE) can be more preferably adopted. Further, the angle formed by the laser irradiation direction, the exterior body 12, and the sealing plate 18 (horizontal plane) is typically about 90 ± 10°, for example, about 90 ± 5°.

[0044] Hereinafter, taking laser welding using an optical diffraction element as an example, an embodiment of the laser welding process S20 will be described. However, it is not limited thereto. FIG. 14 is a schematic diagram showing a laser welding apparatus 120 used in the laser welding process S20 according to an embodiment. As shown in FIG. 14, here, the laser welding apparatus 120 includes a control unit 122, a laser oscillator 124, a collimator (collimating lens) 130, a diffractive optical element 140, a Z lens 160, a galvanometer scanner 170, a condenser lens 180, and a protective glass 190.

[0045] The control unit 122 is a mechanism for controlling the operation of the laser welding apparatus 120. As shown in FIG. 14, here, the control unit 122 is connected to the laser oscillator 124, the diffractive optical element 140 (moving unit 146), and the galvanometer scanner 170 (first mirror 171, second mirror 172). Thereby, the control unit 122 controls the operations of the laser oscillator 124, the diffractive optical element 140, and the galvanometer scanner 170 (first mirror 171, second mirror 172).

[0046] The laser oscillator 124 is a laser light source that generates laser light under the control of the control unit 122. Here, a fiber laser is used as the laser oscillator 124. The laser oscillator 124 is connected here to an emission port 123 made of an optical fiber. The laser generated from the laser oscillator 124 is emitted as emitted laser light 197 from the emission port 123 and enters the collimator 130.

[0047] The collimator 130 is a lens that converts (adjusts) the emitted laser light 197 into parallel light. The collimator 130 is disposed on the downstream side (output side) of the emission port 123. As shown in FIG. 14, the collimator 130 converts the emitted laser light 197 incident from the emission port 123 into parallel laser light 198 and emits it.

[0048] The diffractive optical member 140 is a member that converts the parallel laser light 198 incident from the collimator 130 into diffractive multi-laser light 199 and emits it. The diffractive optical member 140 is disposed on the downstream side (output side) of the collimator 130. FIG. 15 is a schematic diagram showing the diffractive optical member 140 according to an embodiment. FIG. 16 is a schematic diagram showing the configuration of the diffractive optical element portion 142 and the movement of the diffraction region 143 according to an embodiment. In FIG. 15, for convenience of explanation, the movement of the diffractive optical member 140 by the moving unit 146 is indicated by a virtual line. As shown in FIG. 15, here, the diffractive optical member 140 includes a diffractive optical element portion 142, a holding portion 144 that holds the diffractive optical element portion 142, and a moving unit 146 that moves the diffractive optical element portion 142.

[0049] The diffractive optical element portion 142 is a member that defines the irradiation pattern PT of the diffractive multi-laser light 199. As shown in FIG. 15, the diffractive optical element portion 142 is circular and flat here. Here, as shown in FIGS. 15 and 16, the diffractive optical element portion 142 has four regions: a first pattern region 151, a second pattern region 152, a third pattern region 153, and a fourth pattern region 154. A diffractive optical pattern that generates the first irradiation pattern PT1 is formed in the first pattern region 151. A diffractive optical pattern that generates the second irradiation pattern PT2 is formed in the second pattern region 152. A diffractive optical pattern that generates the third irradiation pattern PT3 is formed in the third pattern region 153. A diffractive optical pattern that generates the fourth irradiation pattern PT4 is formed in the fourth pattern region 154. As shown in FIG. 9, the first irradiation pattern PT1 corresponds to the short-side region irradiation laser light Lb that irradiates the short-side region 11a. As shown in FIG. 7, the second irradiation pattern PT2 corresponds to the long-side region irradiation laser light La that irradiates the long-side region 11e. As shown in FIG. 10, the third irradiation pattern PT3 corresponds to the short-side region irradiation laser light Lb that irradiates the short-side region 11b. As shown in FIG. 8, the fourth irradiation pattern PT4 corresponds to the long-side region irradiation laser light La that irradiates the long-side region 11f.

[0050] The moving unit 146 is a mechanism for moving the diffractive optical element unit 142 in the X direction and the Y direction in FIG. 15. The moving unit 146 is connected to the control unit 122 and coupled to the holding unit 144. Under the control of the control unit 122, the diffractive optical member 140 (diffractive optical element unit 142) can be relatively moved (virtual line in FIG. 15) with respect to the parallel laser light 198 incident from the collimator 130. Although details will be described later, by using the moving unit 146 by the control unit 122 to move the diffraction region 143 (see FIG. 16), the diffraction region 143 where the parallel laser light 198 is incident and the diffractive multi-laser light 199 is emitted can be moved. Therefore, the irradiation pattern PT (first to fourth irradiation patterns PT1 to 4) of the diffractive multi-laser light 199 can be changed. Here, it is the movement of the diffraction region 143 due to the movement of the diffractive optical member 140, and the parallel laser light 198 itself does not move.

[0051] The Z lens 160 is a lens for adjusting the focal position SP of the diffractive multi-laser light 199. By moving the Z lens 160 in the optical axis direction (in FIG. 14, the up and down Z direction) under the control of the control unit 122, the focal position SP of the diffractive multi-laser light 199 can be moved (adjusted) in the optical axis direction.

[0052] The galvanometer scanner 170 is a device for controlling the irradiation position of the laser light L. As shown in FIG. 14, the galvanometer scanner 170 includes a first mirror 171 and a second mirror 172, and the first mirror 171 and the second mirror 172 are each controlled by the control unit 122. The first mirror 171 can deflect the diffractive multi-laser light 199 incident through the Z lens 160 in the Y direction by changing the deflection angle under the control of the control unit 122. The second mirror 172 can deflect the diffractive multi-laser light 199 deflected and reflected by the first mirror 171 in the X direction by changing the deflection angle under the control of the control unit 122.

[0053] The light collecting lens 180 and the protective glass 190 are arranged on the downstream side (output side) of the galvanometer scanner 170. By the second mirror 172, the diffracted multi-laser light 199 that has been reflected and deflected is focused at the focal position SP adjusted by the Z lens 160 through the light collecting lens 180 and the protective glass 190, and is scanned (irradiated) onto the case 1 as the laser beam L.

[0054] Here, under the control of the control unit 122, in conjunction with the deflection of the galvanometer scanner 170 (that is, in conjunction with the movement of the laser beam L), the moving unit 146 is driven to move the diffractive optical member 140 (diffractive optical element unit 142), so that the diffractive region 143 follows the movement path 148. As shown in FIG. 16, specifically, the diffractive region 143 passes through the start point 148S within the first pattern region 151 of the movement path 148, and then passes through the second pattern region 152, the third pattern region 153, and the fourth pattern region 154 in this order (illustrated by the white arrows), and after passing through the start point 148S within the first pattern region 151, it is moved to the end point 148E within the first pattern region 151. Thereby, a beam light L having an irradiation pattern PT (first to fourth irradiation patterns PT1 to 4) corresponding to the first to fourth pattern regions 151 to 154 is obtained.

[0055] As described above, the manufacturing method of the power storage device 100 according to the present embodiment has been explained. However, the manufacturing method of the power storage device 100 disclosed herein is not limited to the above-described embodiment. For example, in the above-described embodiment, the pattern (FIG. 6) of the laser light Lb irradiated on the short side region has a line-symmetric pattern in which the peripheral beams 95 and 98 of the second laser light L2 are missing as compared with the laser light La irradiated on the long side region. However, it is not limited to this. FIG. 17 is a plan view schematically showing the pattern of the laser light Lb irradiated on the short side region according to the modified example. FIG. 18 is a longitudinal sectional view schematically showing a state of irradiating the laser light Lb irradiated on the short side region according to the modified example. For example, as shown in FIG. 17, here, the laser light Lb irradiated on the short side region has a pattern in which the peripheral beams 95 and 96 of the second laser light L2 are missing although the pattern of the first laser light L1 is the same. Here, the laser light Lb irradiated on the short side region is asymmetric. As shown in FIG. 18, also in such a modified example, for the short side region 11a, by suppressing the melting of the open short side portion 15a (short side wall 12a) as compared with the sealing plate short side portion 18a, it is possible to suppress the formation of the melt-solidified portion 50 outside the short side wall 12a of the exterior body 12. Therefore, it is possible to suitably suppress the protrusion of the short side walls 12a and 12b of the melt-solidified portion 50. Further, not limited to the above-described pattern configuration, a laser light L having a different irradiation pattern may be generated, or the intensities of the peripheral beams 91 to 98 of the laser light L may be made different from each other. Note that the arrangement and presence or absence of the peripheral beams 91 to 98 of the laser light L, and the strength of each of the peripheral beams 91 to 98 can be adjusted, for example, by changing the configuration of the diffractive optical element portion 142. Further, the shape of the pattern of the laser light L is not limited to this, and for example, it may be a five-point beam (like the five of a die) or a ring beam.

[0056] As another aspect of the technology disclosed herein, a power storage device 100 is provided. The power storage device 100 disclosed herein includes an electrode body 20, an exterior body 12 (short side walls 12a, 12b and long side walls 12e, 12f), a sealing plate 18, a positive electrode terminal 6, a negative electrode terminal 8, and an annular molten and solidified portion 50. The power storage device 100 is characterized by the molten and solidified portion 50, and the other configurations may be the same as those of the prior art. The molten and solidified portion 50 does not protrude outward from the short side walls 12a and 12b, and at least a part of the molten and solidified portion 50 faces the positive electrode terminal 6 or the negative electrode terminal 8 and protrudes outward from the long side wall 12e or the long side wall 12f. Thereby, a power storage device 100 with improved reliability of dimensional accuracy in the long side direction Y is provided.

[0057] The power storage device 100 can be used for various applications, but typically, it can be preferably used as a power source (driving power source) for a motor mounted on various vehicles, such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, and examples include plug-in hybrid vehicles (PHEVs), hybrid vehicles (HEVs), battery electric vehicles (BEVs), etc.

[0058] Some embodiments of the technology disclosed herein have been described above, but the above embodiments are merely examples. The technology disclosed herein can be implemented in various other forms. The technology disclosed herein can be implemented based on the content disclosed in this specification and the common general knowledge in the art. The technology described in the claims includes various modifications and changes of the above-exemplified embodiments. For example, it is possible to replace a part of the above-described embodiments with other modified forms, and it is also possible to add other modified forms to the above-described embodiments. Also, if the technical features are not described as essential, they can be appropriately deleted.

[0059] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A method for manufacturing a power storage device, comprising: an electrode body having electrodes; a rectangular bottom; a pair of short side walls extending from the short sides of the bottom and facing each other; a pair of long side walls extending from the long sides of the bottom and facing each other; an opening facing the bottom; a pair of opening long side portions corresponding to the ends of the long side walls among the peripheral edges of the opening; and a pair of opening short side portions corresponding to the ends of the short side walls; an exterior body for housing the electrode body; a substantially rectangular sealing plate having a pair of sealing plate long side portions and a pair of sealing plate short side portions for sealing the opening of the exterior body; and terminals attached to the sealing plate and electrically connected to the electrode body. The method includes a sealing plate fitting step of housing the electrode body in the exterior body and fitting the sealing plate into the opening of the exterior body, and a laser welding step of scanning the laser beam L over the entire circumference of the sealing plate and the opening to laser-weld the sealing plate and the exterior body. In the laser welding step, the laser beam L is a multi-point laser beam including a first laser beam L1 composed of at least one or more beams irradiating the sealing plate long side portion and the sealing plate short side portion, and a second laser beam L2 composed of at least one or more beams irradiating the opening long side portion and the opening short side portion. When the region composed of the opening long side portion and the sealing plate long side portion is defined as the long side region and the region composed of the opening short side portion and the sealing plate short side portion is defined as the short side region, the energy of the laser beam L irradiating the short side region is smaller than the energy of the laser beam L irradiating the long side region, and the energy of the second laser beam L2 irradiating the short side region is smaller than the energy of the first laser beam L1 irradiating the short side region. Item 2: The method for manufacturing a power storage device according to Item 1, wherein the laser beam L is generated by transmitting and diffracting using a diffractive optical element. Item 3: The method for manufacturing a power storage device according to Item 1 or 2, wherein the number of beams of the first laser beam L1 irradiating the short side region is the same as the number of beams of the first laser beam L1 irradiating the long side region, and the number of beams of the second laser beam L2 irradiating the short side region is less than the number of beams of the second laser beam L2 irradiating the long side region. Item 4: A power storage device comprising an electrode body having electrodes, a rectangular bottom portion, a pair of short side walls extending from the short sides of the bottom portion and facing each other, a pair of long side walls extending from the long sides of the bottom portion and facing each other, an opening facing the bottom portion, an exterior body for housing the electrode body, a substantially rectangular sealing plate for sealing the opening of the exterior body, a terminal attached to the sealing plate and electrically connected to the electrode body, and an annular molten and solidified portion formed at a fitting portion between the opening of the exterior body and the sealing plate, wherein the molten and solidified portion does not protrude outward from the short side walls, and at least a part of the molten and solidified portion faces the terminal and protrudes outward from the long side walls.

Explanation of Signs

[0060] 1 Case 3 Positive electrode 4 Negative electrode 6 Positive electrode terminal 7 Separator 8 Negative electrode terminal 11 Fitting portion 11a, 11b Short side region 11e, 11f Long side region 11g, 11h, 11i, 11j R portion 12 Exterior body 12d Bottom portion 12a, 12b Short side walls 12e, 12f Long side walls 15 Opening 15a, 15b Opening short side portions 15e, 15f Opening long side portions 18 Sealing plate 18a, 18b Sealing plate short side portions 18e, 18f Sealing plate long side portions 20 Electrode body 30 Positive electrode current collector 31 Positive electrode active material layer 35 Positive electrode current collecting member 36 Positive electrode external conductive member 40 Negative electrode current collector 41 Negative electrode active material layer 45 Negative electrode current collecting member 46 Negative electrode external conductive member 50 Molten and solidified portion 71 Injection hole 74 and 75 Terminal lead-out holes 76 Gasket 78 Insulator 90 Central beam 91 - 98 Peripheral beams 100 Energy storage device 120 Laser welding device 122 Control unit 124 Laser oscillator 130 Comerimeter 140 Diffractive optical element 142 Diffractive optical element part 143 Diffraction region 144 Holding part 146 Moving unit 151 First pattern region 152 Second pattern region 153 Third pattern region 154 Fourth pattern region 160 Z - lens 170 Galvanometer scanner 180 Condensing lens 190 Protective glass 197 Emitted laser light 198 Parallel laser light 199 Diffractive multi - laser light L Laser light La Laser light for irradiating long - side region Lb Laser light for irradiating short - side region L1 First laser light L2 Second laser light S10 Sealing plate fitting process S20 Laser welding process

Claims

1. An electrode body having electrodes, A rectangular bottom portion, a pair of short side walls extending from the short sides of the bottom portion and facing each other, a pair of long side walls extending from the long sides of the bottom portion and facing each other, an opening facing the bottom portion, and among the peripheral edges of the opening, a pair of opening long side portions corresponding to the end portions of the long side walls, and a pair of opening short side portions corresponding to the end portions of the short side walls, and an exterior body for housing the electrode body, A substantially rectangular sealing plate having a pair of sealing plate long side portions and a pair of sealing plate short side portions for sealing the opening of the exterior body, A terminal attached to the sealing plate and electrically connected to the electrode body, A method for manufacturing a power storage device, comprising: A sealing plate fitting step of housing the electrode body in the exterior body and fitting the sealing plate into the opening of the exterior body, A laser welding step of scanning laser light L over the entire circumference of the sealing plate and the opening to laser-weld the sealing plate and the exterior body, Comprising: In the laser welding step, The laser light L is A first laser light L1 composed of at least one or more beams irradiating the sealing plate long side portion and the sealing plate short side portion, A multi-point laser light including a second laser light L2 composed of at least one or more beams irradiating the opening long side portion and the opening short side portion, When a region composed of the opening long side portion and the sealing plate long side portion is defined as a long side region and a region composed of the opening short side portion and the sealing plate short side portion is defined as a short side region, The energy of the laser light L irradiating the short side region is smaller than the energy of the laser light L irradiating the long side region, The energy of the second laser light L2 irradiating the short side region is smaller than the energy of the first laser light L1 irradiating the short side region, A method for manufacturing a power storage device.

2. Using a diffractive optical element, the laser light L is generated by transmission diffraction, The method for manufacturing a power storage device according to Claim 1.

3. The number of beam points of the first laser light L1 irradiating the short side region is the same as the number of beam points of the first laser light L1 irradiating the long side region, The number of beam points of the second laser light L2 irradiating the short side region is less than the number of beam points of the second laser light L2 irradiating the long side region, The method for manufacturing a power storage device according to Claim 1 or 2.

Images