Method of manufacturing power storage device

Abstract

To provide a method of manufacturing a power storage device, capable of suppressing occurrence of blowholes in a melted and solidified portion when an unwelded laminated current collector of an electrode body is laser-welded to an unwelded current collecting member.SOLUTION: A method of manufacturing a power storage device 1 includes a laser welding step S2 of overlapping an unwelded laminated current collector 30Z of an electrode body 20 on an unwelded current collecting member 40Z, melting a first region 33 of the unwelded laminated current collector 30Z and a second region 43 of the unwelded current collecting member 40Z through irradiation with a laser beam LB, and forming a melted and solidified portion 38. The unwelded current collecting member 40Z has a gas exhaust channel 45, and the laser welding step S2 includes melting the first region 33 and the second region 43 while exhausting gas to the outside through the gas exhaust channel 45, and forming the melted and solidified portion 38.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electricity storage device including an electrode assembly having a laminated current collector and a current collecting member to which the laminated current collector of the electrode assembly is welded and which is electrically connected to the laminated current collector. [Background technology]

[0002] Known energy storage devices include batteries that include an electrode assembly having positive and negative electrode plates and positive and negative current collectors conductively connected to the electrode assembly. Specifically, the electrode assembly includes a positive electrode laminated current collector formed by laminating foil current collectors with exposed electrode foils among the positive electrode plates, and a negative electrode laminated current collector formed by laminating foil current collectors with exposed electrode foils among the negative electrode plates. The positive electrode laminated current collector of the electrode assembly is welded to the positive electrode current collector, and the negative electrode laminated current collector of the electrode assembly is welded to the negative electrode current collector. Furthermore, in such batteries, the positive electrode current collector is connected to the positive terminal of the battery, and the negative electrode current collector is connected to the negative electrode terminal of the battery. Alternatively, the positive electrode current collector itself extends outside the battery to serve as the positive electrode terminal, and the negative electrode current collector itself extends outside the battery to serve as the negative electrode terminal.

[0003] In manufacturing such batteries, laser welding has been considered for welding the laminated current collector of the electrode assembly to the current collecting member. Specifically, the unwelded laminated current collector is placed on top of the unwelded current collecting member, and a laser beam is irradiated onto the unwelded laminated current collector from above to melt the unwelded laminated current collector and the unwelded current collecting member, which are then solidified to form a molten and solidified portion. In this way, the laminated current collector is welded to the current collecting member. Patent Document 1, for example, is a related prior art document (see Claim 1, Figures 5 and 6, etc., of Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-067570 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it has been found that large or numerous blowholes occur in the melted and solidified portion welded in this manner. During laser welding, gases such as air remain between the multiple foil current collecting portions that form the first portion of the unwelded current collecting laminate to be melted by the laser light, and between this first portion and the second portion of the unwelded current collecting member that overlaps it. Therefore, it is thought that such gases become trapped in the melted and solidified portion during laser welding, causing blowholes.

[0006] The present invention has been made in consideration of the current situation, and provides a method for manufacturing an electricity storage device that can suppress the occurrence of blowholes in the molten and solidified portion when laser welding the unwelded laminated current collecting portion of the electrode body to the unwelded current collecting member. [Means for solving the problem]

[0007] (1) One aspect of the present invention for solving the above-described problems is a method for manufacturing an electricity storage device including: an electrode body having an electrode plate including an electrode foil, the electrode body having a laminated current collecting portion in which foil current collecting portions of the electrode plate, where the electrode foil is exposed, are laminated in a stacking direction; and a current collecting member to which the laminated current collecting portion of the electrode body is welded and electrically connected to the laminated current collecting portion, the method comprising: a laser welding step of overlapping the unwelded laminated current collecting portion before welding on an unwelded current collecting member before welding in the stacking direction, irradiating with laser light to melt a first portion of the unwelded laminated current collecting portion and a second portion of the unwelded current collecting member overlapping with the first portion, and then solidifying the first portion to form a molten and solidified portion, and welding the laminated current collecting portion to the current collecting member, wherein the unwelded current collecting member has a gas exhaust channel in at least the second portion, and the laser welding step melts the first portion and the second portion and discharges gas generated from these portions to the outside through the gas exhaust channel, and then forms the molten and solidified portion.

[0008] In the manufacturing method of the above-described electricity storage device, a gas exhaust path such as a recessed groove or a through-hole is provided in advance in at least the second portion of the unwelded current collecting member to be melted during welding. Then, in the laser welding process, the first portion of the unwelded laminated current collecting member and the second portion of the unwelded current collecting member are melted, and gas generated from these portions is discharged to the outside through the gas exhaust path, and then a melted and solidified portion is formed. This makes it possible to prevent blowholes from occurring in the melted and solidified portion.

[0009] Examples of the "electricity storage device" include secondary batteries such as lithium ion secondary batteries, sodium ion secondary batteries, and calcium ion secondary batteries, and capacitors such as lithium ion capacitors. As will be described later, examples of the "gas exhaust path" include a surface-side gas exhaust groove provided on the overlapping surface of the unwelded current collecting member where the laminated current collecting portion overlaps, a back-side gas exhaust groove provided on the back surface opposite the overlapping surface of the unwelded current collecting member, and a gas exhaust through-hole that penetrates between the overlapping surface and the back surface of the unwelded current collecting member. Note that the surface-side gas exhaust groove will be described in embodiment 1 (see FIGS. 7 and 8, etc.), embodiment 2 (see FIGS. 11 and 12), and embodiment 6 (see FIGS. 19 and 20), the back-side gas exhaust groove will be described in embodiment 3 (see FIGS. 13 and 14), and the gas exhaust through-hole will be described in embodiment 4 (see FIGS. 15 and 16) and embodiment 5 (see FIGS. 17 and 18). As described in embodiments 1 to 6, a portion of the gas exhaust path may remain in the current collecting member after laser welding, or as described in a modified form of embodiment 1 (see Figure 10), due to the formation of a molten and solidified portion by laser welding, the gas exhaust path may not exist in the current collecting member after laser welding.

[0010] The electricity storage device may not only be formed by laser-welding the laminated current collecting portion and the current collecting member, but may also further include another metal member welded to the laminated current collecting portion and the current collecting member, with the laminated current collecting portion of the electrode body sandwiched between the laminated current collecting portion and the current collecting member in the stacking direction, as described in, for example, embodiment 6 (see FIGS. 19 and 20). In this case, in the laser welding step, the unwelded metal member before welding is further stacked on the unwelded laminated current collecting portion stacked on the unwelded current collecting member (i.e., the unwelded laminated current collecting portion is sandwiched between the unwelded current collecting member and the other unwelded metal member), and the three members of the metal member, laminated current collecting portion, and current collecting member are laser-welded.

[0011] (2) Furthermore, in the method for manufacturing an electricity storage device described in (1), the unwelded current collecting member may have an overlapping surface on which the unwelded laminated current collecting portion is overlapped, and the gas discharge path may be provided on the overlapping surface of the unwelded current collecting member, and may be a gas discharge groove on the overlapping surface provided in at least the second portion.

[0012] In the manufacturing method of the electricity storage device described above, the unwelded current collecting member has a overlapping surface-side gas exhaust groove provided in at least the second portion as the gas exhaust path, and therefore, in the laser welding step, gas can be appropriately exhausted from the overlapping surface-side gas exhaust groove to form a melt-solidified portion with no or few blowholes.

[0013] (3) Furthermore, in the method for manufacturing an electric storage device described in (2), the overlapping surface side gas discharge groove has an inverted tapered groove shape that becomes wider from the overlapping surface of the unwelded current collecting member toward the bottom surface of the overlapping surface side gas discharge groove, and the second portion of the unwelded current collecting member preferably includes at least the overlapping surface side portion of the pair of side wall portions that form the overlapping surface side gas discharge groove.

[0014] In the manufacturing method of the above-described electricity storage device, the overlapping-surface-side gas discharge groove has an inverse tapered groove shape, and at least the overlapping-surface-side portion of the pair of sidewall portions of the unwelded current collecting member that form the overlapping-surface-side gas discharge groove is melted as the second portion. This increases the volume of the second portion, and therefore the volume of the molten and solidified portion, compared to when the groove has a tapered groove shape that tapers from the overlapping surface toward the bottom surface or when the groove width does not change in the depth direction, thereby ensuring reliable welding of the current collecting member and the laminated current collecting member. Meanwhile, because the overlapping-surface-side gas discharge groove has an inverse tapered groove shape with a wider bottom surface, generated gas can be easily discharged to the outside through the overlapping-surface-side gas discharge groove, effectively preventing blowholes from occurring in the molten and solidified portion.

[0015] (4) Furthermore, in the method for manufacturing an electricity storage device described in (1), the unwelded current collecting member may have an overlapping surface on which the unwelded laminated current collecting portion is overlapped and a back surface located opposite the overlapping surface, and the gas discharge path may be provided on the back surface of the unwelded current collecting member and may be a back-side gas discharge groove provided in at least the second portion.

[0016] In the manufacturing method of the electricity storage device described above, the unwelded current collecting member has a back-side gas discharge groove provided in a back side portion thereof and in at least the second portion thereof as the gas discharge path, and therefore, in the laser welding step, gas can be appropriately discharged from the back-side gas discharge groove to form a melt-solidified portion with no or few blowholes.

[0017] (5) Furthermore, in the method for manufacturing an electricity storage device described in (1), the unwelded current collecting member may have an overlapping surface on which the unwelded laminated current collecting portion is overlapped and a back surface located on the opposite side to the overlapping surface, and the gas discharge path may be a gas discharge through-hole that penetrates between the overlapping surface and the back surface of the unwelded current collecting member and is provided in at least the second portion.

[0018] In the manufacturing method of the electricity storage device described above, the gas discharge path includes a gas discharge through-hole that penetrates the unwelded current collecting member and is provided in at least the second portion. Therefore, in the laser welding step, gas can be appropriately discharged through the gas discharge through-hole to form a melted and solidified portion that has no or few blowholes. Examples of the "gas discharge through hole" include a through hole whose cross section perpendicular to the depth direction of the through hole has a shape such as a circle, an ellipse, an oval, a rectangle, a polygon, etc. The gas discharge through hole may be a through hole whose cross-sectional shape or size does not change in the depth direction (for example, a cylindrical through hole), or a through hole whose cross-sectional size or shape changes in the depth direction (for example, a tapered through hole that tapers toward the back surface side or a reverse tapered through hole that widens toward the back surface side).

[0019] (6) Furthermore, in the method for manufacturing an electric storage device described in (5), the gas discharge through-hole has an inverse tapered shape in which the diameter increases from the overlapping surface of the unwelded current collecting member toward the back surface, and the second portion of the unwelded current collecting member includes at least the overlapping surface side portion of the inner wall portion forming the gas discharge through-hole.

[0020] In the manufacturing method of the above-described electricity storage device, the gas discharge through hole has an inverse tapered shape that widens toward the back surface, and at least the overlapping surface side of the inner wall portion of the unwelded current collecting member that forms the gas discharge through hole is melted as the second portion. Therefore, compared to when the through hole has a tapered shape that narrows from the overlapping surface toward the back surface or when the through hole has a shape in which the dimensions do not change in the depth direction, the volume of the second portion and therefore the volume of the melted and solidified portion are increased, thereby ensuring reliable welding of the current collecting member and the laminated current collecting member. Meanwhile, because the gas discharge through hole has an inverse tapered shape that is wider toward the back surface, generated gas can be easily discharged to the outside through the gas discharge through hole, effectively suppressing the occurrence of blowholes in the melted and solidified portion. [Brief explanation of the drawings]

[0021] [Figure 1]FIG. 1 is a perspective view of a battery according to a first embodiment. [Figure 2] 1 is a partial cross-sectional view of a battery according to a first embodiment taken along the battery height direction and battery width direction. [Figure 3] 3 is a cross-sectional view of the battery according to the first embodiment taken along the height and thickness directions of the battery, as viewed from the arrows in FIG. 2. FIG. [Figure 4] 2 is a flowchart of a method for manufacturing a battery according to the first embodiment. [Figure 5] 10 is an explanatory diagram seen from above showing the state in which an unwelded laminated current collecting portion of an electrode body is placed on an unwelded current collecting member, and a pressing jig is further placed on top of it, in connection with the manufacturing method of a battery according to Embodiment 1. FIG. [Figure 6] 6 is a cross-sectional view taken along the arrow in FIG. 5, illustrating the state in which an unwelded laminated current collecting part of an electrode body is placed on an unwelded current collecting member, and a pressing jig is further placed on top of it, in the method for manufacturing a battery according to the first embodiment. [Figure 7] 4 is an explanatory view showing how the unwelded laminated current collecting portion is irradiated with laser light while being pressed against an unwelded current collecting member, in connection with the manufacturing method of the battery according to the first embodiment. FIG. [Figure 8] 4 is an explanatory view showing a state in which a melt-solidified portion is formed by performing laser welding in the manufacturing method of the battery according to the first embodiment. FIG. [Figure 9] 4 is an explanatory diagram showing how positive and negative stacked current collecting parts of the electrode body are connected to positive and negative current collecting members in the method for manufacturing the battery according to the first embodiment. FIG. [Figure 10] 10 is an explanatory view showing a state in which a melt-solidified portion is formed by performing laser welding in a battery manufacturing method according to a modified example of the first embodiment. FIG. [Figure 11] 10 is an explanatory view showing a state in which the unwelded laminated current collecting portion is irradiated with laser light while being pressed against an unwelded current collecting member, in connection with the manufacturing method of the battery according to the second embodiment. FIG. [Figure 12] 10 is an explanatory view showing a state in which a melt-solidified portion is formed by laser welding in the battery manufacturing method according to the second embodiment. FIG. [Figure 13]10 is an explanatory view showing a state in which the unwelded laminated current collecting portion is irradiated with laser light while being pressed against an unwelded current collecting member, in connection with the manufacturing method of the battery according to the third embodiment. FIG. [Figure 14] 10 is an explanatory view showing a state in which a melt-solidified portion is formed by laser welding in the battery manufacturing method according to the third embodiment. FIG. [Figure 15] 10 is an explanatory view showing a state in which the unwelded laminated current collecting portion is irradiated with laser light while being pressed against an unwelded current collecting member, in connection with the manufacturing method of the battery according to the fourth embodiment. FIG. [Figure 16] 10 is an explanatory view showing a state in which a melt-solidified portion is formed by laser welding in the battery manufacturing method according to Embodiment 4. FIG. [Figure 17] 13 is an explanatory view showing a state in which the unwelded laminated current collecting portion is irradiated with laser light while being pressed against an unwelded current collecting member, in connection with the manufacturing method of the battery according to the fifth embodiment. FIG. [Figure 18] 13 is an explanatory view showing a state in which a melt-solidified portion is formed by laser welding in the battery manufacturing method according to the fifth embodiment. FIG. [Figure 19] 13 is an explanatory view showing a state in which the unwelded laminated current collecting portion is pressed against the unwelded current collecting member while the laser light is irradiated onto the unwelded metal member, in connection with the manufacturing method of the battery according to the sixth embodiment. FIG. [Figure 20] 13 is an explanatory view showing a state in which a melt-solidified portion is formed by laser welding in the battery manufacturing method according to Embodiment 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] (Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. In the following description, the battery height direction AH, battery width direction BH, and battery thickness direction CH of battery (power storage device) 1 are defined as the directions shown in FIGS. 1 to 3. The battery 1 is a sealed, rectangular (rectangular) lithium-ion secondary battery that is installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles. The battery 1 comprises a case 10, an electrode assembly 20 and an electrolyte 5 housed in the case 10, and positive and negative terminals 50 supported by the case 10 (see FIGS. 1 to 3). The positive electrode current collector 30 of the electrode assembly 20 is connected to the positive electrode terminal 50 via a positive electrode current collector 40, and the negative electrode current collector 30 of the electrode assembly 20 is connected to the negative electrode terminal 50 via a negative electrode current collector 40. The electrode assembly 20 is enclosed within the case 10 in a bag-shaped insulating holder 7 made of an insulating film.

[0023] The case 10 is a rectangular box made of metal (aluminum in the first embodiment). The case 10 is a bottomed, square cylinder having a rectangular annular opening 11c and accommodating the electrode assembly 20 therein. The case 10 is composed of a case body member 11 and a rectangular plate-shaped case lid member 12 that closes the opening 11c of the case body member 11. The opening 11c of the case body member 11 and a peripheral edge 12f of the case lid member 12 are hermetically welded along their entire periphery. The case lid member 12 is provided with a safety valve 10w that ruptures and opens when the internal pressure of the case 10 exceeds a valve opening pressure. The case lid member 12 is also provided with a liquid inlet 10k, which is hermetically sealed with a disk-shaped sealing member 15 made of aluminum.

[0024] Furthermore, insertion holes 10h are provided in the case lid member 12 near the ends of one side BH1 and the other side BH2 in the battery width direction BH. A positive electrode terminal 50 made of aluminum is inserted into the insertion hole 10h on one side BH1, and a negative electrode terminal 50 made of copper is inserted into the insertion hole 10h on the other side BH2. Because the positive and negative terminals 50 have similar shapes, they will be denoted by the same reference numerals and will be described together. The terminals 50 are fixed to the case lid member 12 via an internal insulating member 55 arranged inside the case 10 and an external insulating member 56 arranged mainly outside the case 10.

[0025] The terminal 50 is composed of an internal terminal member 51, an external terminal member 52, and a crimped terminal member 53. The internal terminal member 51 has a rectangular plate shape extending in the battery width direction BH and the battery thickness direction CH, and is disposed inside the case 10. The external terminal member 52 has a rectangular plate shape extending in the battery width direction BH and the battery thickness direction CH, and is disposed outside the case 10. The crimped terminal member 53 is inserted into the insertion hole 10h, and further passes through the internal terminal member 51 and the external terminal member 52, respectively, and is crimped and connected to the internal terminal member 51 and the external terminal member 52. A positive electrode current collecting member 40 (described later) is welded to the internal terminal member 51 of the positive terminal 50, and a negative electrode current collecting member 40 is welded to the internal terminal member 51 of the negative terminal 50.

[0026] Next, the electrode assembly 20 will be described. The electrode assembly 20 is a rectangular parallelepiped laminated type, in which a plurality of positive electrode plates 21 and a plurality of negative electrode plates 21 are alternately laminated with separators 24 made of porous resin films interposed therebetween. The positive and negative electrode plates 21 and separators 24 each have a rectangular shape extending in the battery height direction AH and the battery width direction BH. Because the positive and negative electrode plates 21 have similar shapes, they will be collectively described with the same reference numerals.

[0027] The electrode plate 21 comprises a rectangular electrode foil 22 (aluminum foil for the positive electrode and copper foil for the negative electrode) and an active material layer 23 containing active material particles formed on each of the two main surfaces of the electrode foil 22. A portion of the electrode foil 22 extends upward AH1 in the battery height direction AH. This extended portion of the electrode foil 22 is exposed on both main surfaces without the active material layer 23 present, forming a foil current collecting portion 21r of the electrode plate 21. Portions of each electrode plate 21 having the active material layer 23 on the electrode foil 22 are stacked with separators 24 interposed therebetween to form a main body portion 25 of the electrode assembly 20. Meanwhile, the foil current collecting portions 21r of each electrode plate 21 are stacked together in the stacking direction SH to form a stacked current collecting portion 30 connected to the main body portion 25 of the electrode assembly 20. The tip of the stacked current collecting portion 30 of the positive electrode is welded to a positive current collecting member 40, providing electrical continuity with the current collecting member 40. The negative electrode laminated current collecting portion 30 is welded at its tip to the negative electrode current collecting member 40 and is electrically connected to this current collecting member 40.

[0028] The positive electrode current collecting member 40 is made of aluminum, and the negative electrode current collecting member 40 is made of copper. Because the positive and negative current collecting members 40 have similar shapes, they will be collectively described using the same reference numerals. The current collecting members 40 are rectangular plates extending in the battery width direction BH and the battery thickness direction CH. The positive electrode current collecting member 40 is welded to an internal terminal member 51 of the positive electrode terminal 50 at its end on one side BH1 in the battery width direction BH, and is electrically connected to the positive electrode terminal 50. On the other hand, the negative electrode current collecting member 40 is welded to an internal terminal member 51 of the negative electrode terminal 50 at its end on the other side BH2 in the battery width direction BH, and is electrically connected to the negative electrode terminal 50.

[0029] Next, a method for manufacturing the battery 1 will be described (see FIGS. 4 to 9). First, in an electrode body formation step S1 (see FIG. 4), an electrode body 20 is formed. Specifically, a plurality of rectangular positive electrode plates 21, a plurality of rectangular negative electrode plates 21, and a plurality of rectangular separators 24 are prepared. Then, the positive electrode plates 21 and the negative electrode plates 21 are alternately stacked with the separators 24 sandwiched between them to form the electrode body 20 (see FIGS. 2 and 3).

[0030] Next, in the laser welding process S2 (see Figure 4), unwelded positive and negative current collecting members 40Z before welding are prepared, and the unwelded laminated positive current collecting portion 30Z of the electrode body 20 before welding is laser welded to the unwelded positive current collecting member 40Z, and the unwelded laminated negative current collecting portion 30Z of the electrode body 20 before welding is laser welded to the unwelded negative current collecting member 40Z (see Figures 5 to 9).

[0031] The unwelded laminated current collecting part 30Z of the electrode body 20 has a rectangular plate shape extending in the extension direction JH (left-right direction in FIGS. 5 to 9) from the main body 25 of the electrode body 20. In the first embodiment, the thickness of the unwelded laminated current collecting part 30Z is 1.0 mm when pressed in the stacking direction SH. In the first embodiment, the first region 33 of the unwelded laminated current collecting part 30Z to be melted by laser welding is a region at the tip of the unwelded laminated current collecting part 30Z that extends in the orthogonal direction IH (up-down direction in FIGS. 5 and 9, direction perpendicular to the paper surface in FIGS. 6 to 8) that is orthogonal to the extension direction JH, and that includes the entire stacking direction SH.

[0032] The unwelded current collecting member 40Z has a rectangular plate shape extending in a first direction DH (the up-down direction in FIGS. 5 and 9 ; the direction perpendicular to the paper in FIGS. 6 to 8 ) and a second direction EH (the left-right direction in FIGS. 5 to 9 ) perpendicular thereto. The unwelded current collecting member 40Z has a planar overlapping surface 41 on which the unwelded laminated current collecting part 30Z is overlapped during welding, and a planar back surface 42 located opposite the overlapping surface 41 and parallel to the overlapping surface 41. In the first embodiment, the thickness of the unwelded current collecting member 40Z is 1.0 mm. In the first embodiment, when the unwelded laminated current collecting part 30Z is overlapped on the unwelded current collecting member 40Z, the first direction DH of the unwelded current collecting member 40Z coincides with the orthogonal direction IH of the unwelded laminated current collecting part 30Z, and the second direction EH of the unwelded current collecting member 40Z coincides with the extending direction JH of the unwelded laminated current collecting part 30Z.

[0033] The unwelded current collecting member 40Z has a gas discharge channel 45 at least in the second region 43 melted by laser welding, and in the first embodiment, in an discharge channel forming region 44 including the second region 43. In the first embodiment, the second region 43 is a region of the unwelded current collecting member 40Z that overlaps with the first region 33 of the unwelded laminated current collecting part 30Z, a region on the overlapping surface 41 side, and a region extending in the first direction DH at the center in the second direction EH. The discharge channel forming region 44 includes the entire second region 43 and is a region that extends further on both sides of the second region 43 in the first direction DH.

[0034] The gas discharge path 45 is provided in this discharge path forming portion 44, and is a overlapping surface-side gas discharge groove provided on the overlapping surface 41 side of the unwelded current collecting member 40Z and extending in the first direction DH. Specifically, the longitudinal center portion of the overlapping surface-side gas discharge groove 45 is provided in a portion of the discharge path forming portion 44 that is located on the second portion 43 and its back surface 42 side, and both longitudinal end portions of the overlapping surface-side gas discharge groove 45 are provided beyond the second portion 43 on both sides in the first direction DH and in a portion of the discharge path forming portion 44 that is not the second portion 43. The overlapping surface-side gas discharge groove 45 has a bottom surface 45b parallel to the overlapping surface 41 and the back surface 42 of the unwelded current collecting member 40Z, and a pair of side surfaces 45a extending from the bottom surface 45b to the overlapping surface 41, and the groove width is constant from the bottom surface 45b to the overlapping surface 41 (the groove width does not change in the depth direction) (see FIG. 7). In this embodiment 1, the overlapping surface-side gas discharge groove 45 has a width (dimension in the second direction EH) of 0.6 mm, a depth of 0.4 mm, and a length (dimension in the first direction DH) of 5.0 mm.

[0035] In this embodiment 1, the overlapping surface side gas discharge groove 45 is provided in a portion of the first direction DH of the unwelded current collecting member 40Z, but as shown by the dotted line in Figure 5, the overlapping surface side gas discharge groove 45 may be provided over the entire first direction DH of the unwelded current collecting member 40Z, that is, extending from one end to the other end of the unwelded current collecting member 40Z in the first direction DH.

[0036] In the laser welding step S2, first, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 41 of the unwelded current collecting member 40Z in the stacking direction SH (see FIGS. 5 to 7). A pair of pressing jigs PJ is then placed on the unwelded laminated current collecting part 30Z, and the pair of pressing jigs PJ press the unwelded laminated current collecting part 30Z downward toward the unwelded current collecting member 40Z. Each of the pair of pressing jigs PJ has a rectangular parallelepiped shape, and presses both outer portions 35 of the unwelded laminated current collecting part 30Z in the extending direction JH of the first portion 33, avoiding the first portion 33 of the unwelded laminated current collecting part 30Z.

[0037] Next, laser light LB is irradiated from above toward the first portion 33 of the unwelded laminated current collecting part 30Z to melt the first portion 33 and the second portion 43 of the unwelded current collecting member 40Z that overlaps the first portion 33, and then solidifies them to form a melted and solidified portion 38, thereby welding the laminated current collecting part 30 to the current collecting member 40 (see FIGS. 8 and 9). In this first embodiment, a YAG laser was used. The melted and solidified portion 38 has a width (dimensions in the extension direction JH and second direction EH) of 2.0 mm and a length (dimensions in the orthogonal direction IH and first direction DH) of 4.0 mm.

[0038] During this laser welding, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 43 of the unwelded current collecting member 40Z are melted, and gas generated from these portions 33, 43 is discharged to the outside through the overlapping surface-side gas discharge groove 45, after which the melted and solidified portion 38 is formed. This makes it possible to prevent blowholes from occurring in the melted and solidified portion 38. Note that, because the overlapping surface-side gas discharge groove 45 extends in the first direction DH, gas is discharged to the outside from both sides of the overlapping surface-side gas discharge groove 45 in the first direction DH.

[0039] In the first embodiment, the second portions 43 of the unwelded current collecting member 40Z are overlapping surface side portions 46t on the overlapping surface 41 side of both side wall portions 46 of the unwelded current collecting member 40Z, which form both side surfaces 45a of the overlapping surface-side gas discharge groove 45. The portions of the both side wall portions 46 of the unwelded current collecting member 40Z on the back surface 42 side and the bottom portions 47 of the unwelded current collecting member 40Z, which form the bottom surfaces 45b of the overlapping surface-side gas discharge groove 45, remain unmelted even after welding, and a portion of the overlapping surface-side gas discharge groove 45 on the bottom surface 45b side remains even after welding (see FIG. 8).

[0040] 10 shows a modified embodiment of the first embodiment, the second portion 43 of the unwelded current collecting member 40Z may be the entirety of both side wall portions 46 and the entirety of the bottom portion 47 of the unwelded current collecting member 40Z. In this case, due to the formation of the molten and solidified portion 38 by laser welding, the gas discharge groove 45 is not present on the back surface 42 of the molten and solidified portion 38 in the current collecting member 40 after laser welding. However, as in the first embodiment described above, it is preferable to leave part of the gas discharge groove 45 on the back surface 42 of the molten and solidified portion 38, because this allows gas to be more appropriately discharged to the outside through the gas discharge groove 45 during welding.

[0041] Separately, in a terminal fixing step S3 (see FIG. 4), a case lid member 12 is prepared, and positive and negative terminals 50 are fixed to this case lid member 12 (see FIGS. 1 to 3). Specifically, a positive electrode internal terminal member 51, an external terminal member 52, a crimped terminal member 53, an internal insulating member 55, and an external insulating member 56 are prepared. Then, the internal insulating member 55 and the external insulating member 56 are arranged in predetermined positions in the case lid member 12, and the internal terminal member 51, the external terminal member 52, and the crimped terminal member 53 are arranged. By crimping the crimped terminal member 53, a positive electrode terminal 50 consisting of the internal terminal member 51, the external terminal member 52, and the crimped terminal member 53 is formed, and the terminal 50 is fixed to the case lid member 12 while being insulated. The negative electrode terminal 50 is also formed in the same manner as the positive electrode terminal 50.

[0042] Next, in a connecting step S4 (see FIG. 4 ), the positive and negative current collecting members 40 connected to the electrode body 20 in the laser welding step S2 are connected to the positive and negative terminals 50 supported by the case lid member 12. Specifically, a portion of the positive current collecting member 40 is overlapped with a portion of the internal terminal member 51 of the positive terminal 50, and laser light is irradiated onto the current collecting member 40 from above, thereby laser-welding the current collecting member 40 to the internal terminal member 51. As with the positive electrode, for the negative electrode, the negative current collecting member 40 is laser-welded to the negative internal terminal member 51. The electrode body 20 is then wrapped in a bag-shaped insulating holder 7.

[0043] Next, in the case formation process S5 (see FIG. 4), a case body member 11 is prepared, the electrode body 20 covered with the insulating holder 7 is inserted into the case body member 11, and the opening 11c of the case body member 11 is closed with the case lid member 12. Then, the opening 11c of the case body member 11 and the peripheral edge 12f of the case lid member 12 are laser-welded airtightly along their entire peripheries to form the case 10. Next, in a liquid injection and sealing step S6, the electrolyte 5 is injected into the case 10 through the liquid injection hole 10k, and the electrolyte 5 is impregnated into the electrode body 20. Thereafter, the liquid injection hole 10k is sealed with a sealing member 15 in an airtight manner. Next, in the initial charge / aging step S7, the battery 1 is initially charged. After that, the battery 1 is left standing for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

[0044] In the manufacturing method of the battery 1 of the first embodiment, a gas discharge channel 45 is provided in advance in at least the second portion 43 of the unwelded current collecting member 40Z. Then, in the laser welding step S2, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 43 of the unwelded current collecting member 40Z are melted, and gas generated from these portions 33, 43 is discharged to the outside through the gas discharge channel 45, and then the melted and solidified portion 38 is formed. This makes it possible to suppress the occurrence of blowholes in the melted and solidified portion 38. Furthermore, in the present embodiment 1, the gas discharge path 45 is provided in a portion of the unwelded current collecting member 40Z on the overlapping surface 41 side, and is a overlapping surface-side gas discharge groove provided in at least the second portion 43. Therefore, in the laser welding step S2, gas can be appropriately discharged from this overlapping surface-side gas discharge groove 45, and a melted and solidified portion 38 with no or few blowholes can be formed.

[0045] (Embodiment 2) Next, a second embodiment will be described (see FIGS. 11 and 12). Descriptions of parts similar to those of the first embodiment will be omitted or simplified. In the second embodiment, the shape of the overlapping surface-side gas discharge groove (gas discharge channel) 145 provided in advance in the unwelded current collecting member 140Z used in manufacturing the battery 100 differs from the shape of the overlapping surface-side gas discharge groove 45 provided in the unwelded current collecting member 40Z according to the first embodiment.

[0046] Specifically, the unwelded current collecting member 140Z of the second embodiment also has a surface-side gas discharge groove 145 that is provided on the overlapping surface 141 of the unwelded current collecting member 140Z and extends in the first direction DH in a discharge path formation region 144 that includes a second region 143 that is melted by laser welding (see FIG. 11 ). The surface-side gas discharge groove 145 has a bottom surface 145b that is parallel to the overlapping surface 141 and the back surface 142 of the unwelded current collecting member 140Z, and a pair of side surfaces 145a that extend from the bottom surface 145b to the overlapping surface 141. However, unlike the surface-side gas discharge groove 45 of the first embodiment, the surface-side gas discharge groove 145 of the second embodiment has an inversely tapered groove shape that becomes wider from the overlapping surface 141 toward the bottom surface 145b.

[0047] In the laser welding step S2, similar to the first embodiment, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 141 of the unwelded current collecting member 140Z in the stacking direction SH, and a pair of pressing jigs PJ are placed on top of each other to press the unwelded laminated current collecting part 30Z against the unwelded current collecting member 140Z. Next, a laser beam LB is irradiated toward a first portion 33 of the unwelded laminated current collecting part 30Z to melt the first portion 33 and a second portion 143 of the unwelded current collecting member 140Z that overlaps with the first portion 33, and then solidifies the melted and solidified portion 138 to weld the laminated current collecting part 30 to the current collecting member 140 (see FIG. 12 ). In the second embodiment, the second portion 143 of the unwelded current collecting member 140Z is also the overlapping surface side portion 146t on the overlapping surface 141 side of both side wall portions 146 forming both side surfaces 145a of the overlapping surface side gas discharge groove 145.

[0048] In the second embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 143 of the unwelded current collecting member 140Z are melted, and gas generated from these portions 33, 143 is appropriately discharged to the outside through the overlapping surface-side gas discharge groove 145, and then solidified to form the melted and solidified portion 138. Therefore, the occurrence of blowholes in the melted and solidified portion 138 can be suppressed.

[0049] Furthermore, in the second embodiment, the overlapping surface-side gas discharge groove 145 has an inversely tapered groove shape, and the overlapping surface side portions 146t of the pair of side wall portions 146 that form the overlapping surface-side gas discharge groove 145 of the unwelded current collecting member 140Z are melted as the second portion 143. Therefore, compared to the gas discharge groove 45 of the first embodiment, in which the groove width does not change in the depth direction, the volume of the second portion 143 and therefore the volume of the molten and solidified portion 138 are increased, thereby ensuring reliable welding of the current collecting member 140 and the laminated current collecting unit 30. Meanwhile, because the overlapping surface-side gas discharge groove 145 has an inversely tapered groove shape that is wider on the bottom surface 145b side, generated gas can be easily discharged to the outside through the overlapping surface-side gas discharge groove 145, effectively preventing blowholes from occurring in the molten and solidified portion 138. Other features similar to those of the first embodiment also function and function in the second embodiment.

[0050] (Embodiment 3) Next, a third embodiment will be described (see FIGS. 13 and 14). Descriptions of parts similar to those of the first or second embodiment will be omitted or simplified. In this third embodiment, the shape of a gas discharge channel 245 provided in advance in an unwelded current collecting member 240Z used in manufacturing a battery 200 differs from the shapes of the gas discharge channels 45, 145 provided in the unwelded current collecting members 40Z, 140Z of the first and second embodiments.

[0051] Specifically, the unwelded current collecting member 240Z of the third embodiment has a back-side gas discharge groove provided on the back surface 242 of the unwelded current collecting member 240Z and extending in the first direction DH in a discharge path formation region 244 including a second region 243 melted by laser welding (see FIG. 13 ). The back-side gas discharge groove 245 has a bottom surface 245b parallel to the overlapping surface 241 and the back surface 242, and a pair of side surfaces 245a extending from the bottom surface 245b to the back surface 241. The groove width is constant from the bottom surface 245b to the back surface 241.

[0052] In the laser welding step S2, similar to the first embodiment, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 241 of the unwelded current collecting member 240Z in the stacking direction SH, and a pair of pressing jigs PJ are placed on top of each other to press the unwelded laminated current collecting part 30Z against the unwelded current collecting member 240Z. Laser light LB is then irradiated toward the first portion 33 of the unwelded laminated current collecting part 30Z to melt the first portion 33 and a second portion 243 of the unwelded current collecting member 240Z that overlaps the first portion 33. These portions are then solidified to form a molten and solidified portion 238, thereby welding the laminated current collecting part 30 to the current collecting member 240 (see FIG. 14 ). In the third embodiment, the second portion 243 of the unwelded current collecting member 240Z corresponds to the entire thickness direction of a central portion of a bottom portion 247 that forms the bottom surface 245b of the back-side gas discharge groove 245.

[0053] In the third embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 243 of the unwelded current collecting member 240Z are melted, and gas generated from these portions 33, 243 is discharged to the outside through the gas discharge path 245, and then solidified to form the melted and solidified portion 238. Therefore, the occurrence of blowholes in the melted and solidified portion 238 can be suppressed. Furthermore, in the third embodiment, the gas discharge path 245 is a back-side gas discharge groove 245 provided in a portion of the unwelded current collecting member 240Z on the back surface 242 side, and provided in at least the second portion 243. Therefore, in the laser welding step S2, gas can be appropriately discharged from this back-side gas discharge groove 245, and a melt-solidified portion 238 with no or few blowholes can be formed. Other portions similar to those in the first or second embodiment also have similar effects in the third embodiment.

[0054] (Embodiment 4) Next, a fourth embodiment will be described (see FIGS. 15 and 16). Descriptions of parts similar to those of any of the first to third embodiments will be omitted or simplified. In this fourth embodiment, the shape of a gas discharge channel 345 provided in advance in an unwelded current collecting member 340Z used in manufacturing a battery 300 differs from the shapes of the gas discharge channels 45, 145, and 245 provided in the unwelded current collecting members 40Z, 140Z, and 240Z of the first to third embodiments.

[0055] Specifically, the unwelded current collecting member 340Z of the fourth embodiment has, as a gas discharge path 345, a gas discharge through-hole that penetrates between the overlapping surface 341 and the back surface 342 of the unwelded current collecting member 340Z, extends in the first direction DH, and has an elongated rectangular cross section perpendicular to the depth direction of the through-hole (see FIG. 15 ), in a discharge path formation portion 344 including a second portion 343 to be melted by laser welding. The gas discharge through-hole 345 has a constant dimension in the second direction EH from the overlapping surface 341 to the back surface 342 (a shape that does not change in the depth direction), and has a shape in which the size of the cross section perpendicular to the depth direction (opening area) does not change in the depth direction.

[0056] In the laser welding step S2, similarly to the first embodiment, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 341 of the unwelded current collecting member 340Z in the stacking direction SH, and a pair of pressing jigs PJ are placed on top of each other to press the unwelded laminated current collecting part 30Z against the unwelded current collecting member 340Z. Next, laser light LB is irradiated toward the first portion 33 of the unwelded laminated current collecting part 30Z to melt the first portion 33 and a second portion 343 of the unwelded current collecting member 340Z that overlaps with the first portion 33, and then solidifies the melted and solidified portion 338 to weld the laminated current collecting part 30 to the current collecting member 340 (see FIG. 16 ). In the fourth embodiment, the second portion 343 of the unwelded current collecting member 340Z is an overlapping surface side portion 348t on the overlapping surface 341 side of the inner wall portion 348 that forms the inner circumferential surface 345c of the gas discharge through-hole 345.

[0057] In the fourth embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 343 of the unwelded current collecting member 340Z are melted, and gas generated from these portions 33, 343 is discharged to the outside through the gas discharge path 345, and then solidified to form the melted and solidified portion 338. Therefore, the occurrence of blowholes in the melted and solidified portion 338 can be suppressed. Furthermore, in the fourth embodiment, the gas discharge path 345 is a gas discharge through-hole 345 that penetrates the unwelded current collecting member 340Z and is provided in at least the second portion 343. Therefore, in the laser welding step S2, gas can be appropriately discharged from this gas discharge through-hole 345, and a melt-solidified portion 338 with no or few blowholes can be formed. Other parts similar to those in any of the first to third embodiments also have similar effects in the fourth embodiment.

[0058] (Embodiment 5) Next, a fifth embodiment will be described (see FIGS. 17 and 18). Descriptions of parts similar to those of any of the first to fourth embodiments will be omitted or simplified. In the fifth embodiment, the shape of the gas discharge through-hole (gas discharge path) 445 provided in advance in the unwelded current collecting member 440Z used in manufacturing the battery 400 differs from the shape of the gas discharge through-hole 345 provided in the unwelded current collecting member 340Z of the fourth embodiment.

[0059] Specifically, the unwelded current collecting member 440Z of the fifth embodiment also has a gas discharge through-hole 445 that penetrates between the overlapping surface 441 and the back surface 442 of the unwelded current collecting member 440Z and extends in the first direction DH in a discharge path forming portion 444 including a second portion 443 to be melted by laser welding (see FIG. 17). However, unlike the gas discharge through-hole 345 of the fourth embodiment, the gas discharge through-hole 445 of the fifth embodiment has a diameter that increases from the overlapping surface 441 toward the back surface 442 (the area of ​​the opening perpendicular to the depth direction increases toward the back surface 442), specifically, has a reverse tapered shape in which the dimension in the second direction EH increases toward the back surface 442.

[0060] In the laser welding step S2, similarly to the first embodiment, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 441 of the unwelded current collecting member 440Z in the stacking direction SH, and a pair of pressing jigs PJ are placed on top of each other to press the unwelded laminated current collecting part 30Z against the unwelded current collecting member 440Z. Next, laser light LB is irradiated toward the first portion 33 of the unwelded laminated current collecting part 30Z to melt the first portion 33 and a second portion 443 of the unwelded current collecting member 440Z that overlaps with the first portion 33, and then solidifies the melted and solidified portion 438 to weld the laminated current collecting part 30 to the current collecting member 440 (see FIG. 18 ). In the fifth embodiment, the second portion 443 of the unwelded current collecting member 440Z is an overlapping surface side portion 448t on the overlapping surface 441 side of an inner wall portion 448 forming the inner circumferential surface 445c of the gas discharge through-hole 445.

[0061] In the fifth embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 443 of the unwelded current collecting member 440Z are melted, and gas generated from these portions 33, 443 is discharged to the outside through the gas discharge through-holes 445, and then solidified to form the melted and solidified portion 438. Therefore, the occurrence of blowholes in the melted and solidified portion 438 can be suppressed.

[0062] Furthermore, in the fifth embodiment, the gas discharge through hole 445 has an inversely tapered shape that is wider on the back surface 442 side, and the overlapping surface side portion 448t of the inner wall portion 448 that forms the gas discharge through hole 445 of the unwelded current collecting member 440Z is melted as the second portion 443. Therefore, compared to the gas discharge through hole 345 of the fourth embodiment, whose dimensions do not change in the depth direction, the volume of the second portion 443 and therefore the volume of the molten and solidified portion 438 are increased, thereby ensuring reliable welding of the current collecting member 440 and the laminated current collecting unit 30. Meanwhile, because the gas discharge through hole 445 has an inversely tapered shape that is wider on the back surface 442 side, generated gas can be easily discharged to the outside through the gas discharge through hole 445, effectively preventing blowholes from occurring in the molten and solidified portion 438. Other features similar to those of any of the first to fourth embodiments also have similar effects in the fifth embodiment.

[0063] (Embodiment 6) Next, a sixth embodiment will be described (see Figs. 19 and 20). Descriptions of parts similar to those of any of the first to fifth embodiments will be omitted or simplified. A battery 500 of this sixth embodiment further comprises, in the battery 1 of the first embodiment, another metal member 560, which sandwiches the laminated current collecting section 30 of the electrode body 20 between itself and the current collecting member 40 in the stacking direction SH, and is welded to the laminated current collecting section 30 and the current collecting member 40 (see Fig. 20).

[0064] Specifically, the metal member 560 has a rectangular plate shape extending in the battery width direction BH and the battery thickness direction CH. The positive electrode metal member 560 is made of aluminum, and the negative electrode metal member 560 is made of copper. In the laser welding process S2, the unwelded laminated current collecting part 30Z is placed on the overlapping surface 41 of the unwelded current collecting member 40Z in the stacking direction SH, and an unwelded metal member 560Z is placed on top of that, and a pair of pressing jigs PJ is placed on top of that (see FIG. 19). The unwelded metal member 560Z is pressed with the pair of pressing jigs PJ to press the unwelded laminated current collecting part 30Z toward the unwelded current collecting member 40Z. Next, laser light LB is irradiated onto the unwelded metal member 560Z to melt the third portion 563 of the unwelded metal member 560Z, the first portion 33 of the unwelded laminated current collecting part 30Z, and the second portion 43 of the unwelded current collecting member 40Z, which are then solidified to form a melt-solidified portion 538 (see FIG. 20). This welds the metal member 560, the laminated current collecting part 30, and the current collecting member 40.

[0065] In the laser welding step S2, the third portion 563 of the unwelded metal member 560Z, the first portion 33 of the unwelded laminated current collecting portion 30Z, and the second portion 43 of the unwelded current collecting member 40Z are melted, and gas generated from these portions 563, 33, and 43 is appropriately discharged to the outside through the overlapping surface-side gas discharge groove 45, and then solidified to form the melted and solidified portion 538. This makes it possible to prevent blowholes from occurring in the melted and solidified portion 538. In addition, the same parts as those in any of the first to fifth embodiments also have the same functions and effects in the sixth embodiment.

[0066] The present invention has been described above in accordance with embodiments 1 to 6, but it goes without saying that the present invention is not limited to embodiments 1 to 6 and can be modified and applied as appropriate within the scope of the gist of the present invention. For example, in the first to sixth embodiments, the battery 1 and the like are illustrated as including a single electrode body 20, but the battery may include multiple electrode bodies. In this case, multiple positive and negative current collecting members may be prepared, and the positive and negative stacked current collecting parts may be welded to the positive and negative current collecting members for each electrode body, or one positive and one negative current collecting member may be prepared, and the stacked current collecting parts for multiple positive electrodes may be welded to one positive current collecting member, and the stacked current collecting parts for multiple negative electrodes may be welded to one negative current collecting member. In addition, in embodiments 1 to 6, a laminated electrode body is exemplified as the electrode body, but this is not limited thereto, and the electrode body may also be a flat wound type in which positive and negative strip-shaped electrode plates are wound flatly with a pair of strip-shaped separators interposed therebetween.

[0067] Furthermore, in the first to sixth embodiments, the laser welding step S2 is performed using a YAG laser, but the laser is not limited to this, and for example, a fiber laser, a disk laser, a blue laser, a green laser, or the like can be used as appropriate. Furthermore, in the first to sixth embodiments, the battery 1 etc. has been exemplified in which the positive electrode current collecting member 40 etc. is connected to the positive electrode terminal 50 of the battery 1 etc., and the negative electrode current collecting member 40 etc. is connected to the negative electrode terminal 50 of the battery 1 etc., but this is not limiting. A battery may also be one in which the positive electrode current collecting member itself extends to the outside of the battery to serve as the positive electrode terminal of the battery, and the negative electrode current collecting member itself extends to the outside of the battery to serve as the negative electrode terminal of the battery. [Explanation of symbols]

[0068] 1,100,200,300,400,500 Batteries (energy storage devices) 10 cases 20 Electrode body 21 Electrode plate 21r Foil current collector 22 Electrode foil 30 Laminated current collector 30Z Unwelded laminated current collector 33 Part 1 38,138,238,338,438,538 Melting and solidification part 40,140,240,340,440 Current collecting member 40Z, 140Z, 240Z, 340Z, 440Z Unwelded current collecting members 41,141,241,341,441 overlapping surfaces 42,142,242,342,442 Back side 43,143,243,343,443 2nd part 45,145 Gas exhaust groove on overlapping surface (gas exhaust path) 245 Backside gas exhaust groove (gas exhaust path) 345,445 Gas exhaust through hole (gas exhaust path) 45b, 145b, 245b bottom 46,146 Side wall 46t, 146t (side wall) overlapping surface side 348,448 Inner wall 348t, 448t (inner wall) overlapping surface side 50 terminals SH (Laminated current collector) stacking direction PJ pressing jig S2 laser welding process

Claims

1. an electrode body having electrode plates including electrode foil, the electrode body having a laminated current collecting portion in which foil current collecting portions of the electrode plates where the electrode foil is exposed are laminated in a lamination direction; a current collecting member to which the laminated current collecting portion of the electrode body is welded and which is electrically connected to the laminated current collecting portion. A method for manufacturing an electricity storage device, comprising: The unwelded laminated current collecting portion before welding is stacked on the unwelded current collecting member before welding in the stacking direction; A laser beam is applied to melt a first portion of the unwelded laminated current collecting portion and a second portion of the unwelded current collecting member that overlaps with the first portion, and then the melted and solidified portion is formed by solidifying the melted and solidified portion, thereby welding the laminated current collecting portion to the current collecting member. Equipped with a laser welding process, the unwelded current collecting member has a gas exhaust passage at least in the second portion, The laser welding process includes: The first portion and the second portion are melted, and gas generated from these portions is discharged to the outside through the gas discharge path, and then the melt-solidified portion is formed. A method for manufacturing an electricity storage device.

2. A method for manufacturing the electricity storage device according to claim 1, the unwelded current collecting member has an overlapping surface on which the unwelded laminated current collecting portion overlaps, The gas discharge path is provided on the overlapping surface of the unwelded current collecting member, and is a overlapping surface-side gas discharge groove provided in at least the second portion. A method for manufacturing an electricity storage device.

3. A method for manufacturing the electricity storage device according to claim 2, the overlapping surface-side gas discharge groove has an inversely tapered groove shape that widens from the overlapping surface of the unwelded current collecting member toward a bottom surface of the overlapping surface-side gas discharge groove, The second portion of the unwelded current collecting member includes at least the overlapping surface side portion of the pair of side wall portions that form the overlapping surface-side gas discharge groove. A method for manufacturing an electricity storage device.

4. A method for manufacturing the electricity storage device according to claim 1, the unwelded current collecting member has an overlapping surface on which the unwelded laminated current collecting portion overlaps, and a back surface located on the opposite side to the overlapping surface, The gas discharge path is provided on the back surface of the unwelded current collecting member, and is a back surface side gas discharge groove provided in at least the second portion. A method for manufacturing an electricity storage device.

5. A method for manufacturing the electricity storage device according to claim 1, the unwelded current collecting member has an overlapping surface on which the unwelded laminated current collecting portion overlaps, and a back surface located on the opposite side to the overlapping surface, The gas exhaust path is a gas exhaust through-hole that penetrates between the overlapping surface and the back surface of the unwelded current collecting member and is provided in at least the second portion. A method for manufacturing an electricity storage device.

6. A method for manufacturing the electricity storage device according to claim 5, the gas discharge through-hole has an inverse tapered shape whose diameter increases from the overlapping surface toward the back surface of the unwelded current collecting member, The second portion of the unwelded current collecting member includes at least a side portion of the inner wall portion of the gas discharge through hole that is on the overlapping surface side. A method for manufacturing an electricity storage device.

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