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 that has: a placement step S20 of placing an unwelded laminated current collector 30Z of an electrode body 20 over a space between a pair of elongate protrusions 46 of an unwelded current collecting member 40Z; an adhesion step S21 of pressing a pair of outer regions 36 of the unwelded laminated current collector 30Z against the unwelded current collecting member 40Z to cause foil bridge portions 21ra of foil current collectors 21r to adhere to each other; and a melting and solidifying step S22 of melting a first region 33 of the unwelded laminated current collector 30Z and a second region 43 of the unwelded current collecting member 40Z while exhausting gas to the outside through a gas exhaust recessed groove 45, and forming a 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 problem 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 lamination 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 including: stacking the unwelded laminated current collecting portion before welding on the unwelded current collecting member before welding in the lamination direction, and irradiating a laser beam to a first portion of the unwelded laminated current collecting portion and a portion of the unwelded current collecting member overlapping with the first portion. and a laser welding step of welding the laminated current collecting part to the current collecting member by melting the second portion of the unwelded current collecting part and then solidifying it to form a melted and solidified part, and the unwelded current collecting member has an opposing surface facing the unwelded laminated current collecting part and a pair of protruding ridge portions protruding from the opposing surface, the pair of protruding ridge portions being a gas discharge groove between the pair of protruding ridge portions, the opposing surface including a pair of outer opposing surface portions located on both outsides in an arrangement direction of the pair of protruding ridge portions, and the laser welding step includes a step of bridging the unwelded laminated current collecting part between the pair of protruding ridge portions of the unwelded current collecting member. and a disposing step of providing a bridging portion that is bridged between the protruding portions and a pair of outer portions that are located on both sides of the bridging portion in the arrangement direction and overlap the pair of outer facing surface portions of the unwelded current collecting member; and a step of pressing the pair of outer portions of the unwelded laminated current collecting portion against the pair of outer facing surface portions of the unwelded current collecting member to press a pair of bridging end portions on one side and the other side in the arrangement direction of the bridging portion against the protruding portions, and and a melting and solidifying process in which at least a portion of the bridge portion of the unwelded stacked current collecting member is defined as the first portion, and at least a portion of each of the protruding strip portions of the unwelded current collecting member is defined as the second portion, and the first portion and the second portion are melted and gas generated from these portions is discharged to the outside through the gas discharge groove, and then the melted and solidified portion is formed.

[0008] In the manufacturing method of the above-described electricity storage device, a pair of ridges forming a gas discharge groove is pre-formed on the unwelded current collecting member before welding. Then, in the laser welding process, during the bonding process, a pair of outer portions of the unwelded laminated current collecting member are pressed against a pair of outer facing surfaces of the unwelded current collecting member, and a pair of bridge ends of the bridge portions are pressed against the ridges. Furthermore, tension is applied in the arrangement direction to the foil bridge portions included in the bridge portions of each foil current collecting member constituting the unwelded laminated current collecting member, thereby bonding the foil bridge portions together in the stacking direction. This reduces the amount of gas present in the bridge portions of the unwelded laminated current collecting member. Then, during the melting and solidifying process, at least a portion of the bridge portion of the unwelded laminated current collecting member is designated as the first portion, and at least a portion of each ridge portion of the unwelded current collecting member is designated as the second portion. These portions are melted, and gas generated from these portions is discharged to the outside through the gas discharge groove, forming a melted and solidified portion. These features make it possible to prevent blowholes from occurring in the melt-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. The "pair of ridges" may partially remain on the current collecting member after laser welding, or may not be present on the current collecting member after laser welding due to the formation of a melt-solidified portion by laser welding. Similarly, the "gas discharge groove" may partially remain on the current collecting member after laser welding, or may not be present on the current collecting member after laser welding due to the formation of a melt-solidified portion by laser welding.

[0010] (2) Furthermore, in the method for manufacturing an electric storage device described in (1), the pair of convex rib portions of the unwelded current collecting member each have a flat top surface, and the adhesion process may be a method for manufacturing an electric storage device in which a pair of the bridging ends of the bridging portion of the unwelded laminated current collecting member are pressed against the flat top surfaces of the pair of convex rib portions, respectively.

[0011] In the manufacturing method of the electricity storage device described above, the pair of ridges of the unwelded current collecting member have flat top surfaces, and in the adhesion step, the pair of bridging ends of the bridging portion of the unwelded laminated current collecting part are pressed against these flat top surfaces, thereby reliably preventing cracks or other damage to the parts of the foil current collecting part that form the bridging ends due to pressing against the ridges.

[0012] (3) Furthermore, in the method for manufacturing an electric storage device described in (1) or (2), the pair of outer facing surface portions of the unwelded current collecting member may each be a flat surface, and the adhesion process may be a method for manufacturing an electric storage device in which the pair of outer portions of the unwelded laminated current collecting member are pressed against the pair of flat outer facing surface portions of the unwelded current collecting member using a pair of flat pressing surfaces of a pressing jig.

[0013] In the manufacturing method of the electricity storage device described above, the pair of outer facing surfaces of the unwelded current collecting member are flat, and in the adhesion step, the pair of outer regions of the unwelded laminated current collecting member are pressed against the pair of flat outer facing surfaces of the unwelded current collecting member by the flat pressing surfaces of the pressing jig. This allows the outer regions to be appropriately pressed against the outer facing surfaces of the unwelded current collecting member without causing damage such as cracks in the portions of the foil current collecting member that form the outer regions. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a battery according to an embodiment. [Figure 2] 1 is a partial cross-sectional view of a battery according to an embodiment, taken along the battery height direction and the battery width direction. [Figure 3] 3 is a cross-sectional view of the battery according to the embodiment taken along the arrows in FIG. 2 along the battery height direction and the battery thickness direction. [Figure 4] 3 is a flowchart of a method for manufacturing a battery according to an embodiment. [Figure 5] 10 is an explanatory diagram showing, viewed from above, the state in which the unwelded laminated current collecting portion of the electrode body is placed on the unwelded current collecting member and then pressed with a pressing jig, in the manufacturing method of the battery according to the embodiment. FIG. [Figure 6] 6 is a cross-sectional view taken along the arrow in FIG. 5, showing how an unwelded laminated current collecting part of an electrode body is placed on an unwelded current collecting member and then pressed with a pressing jig. [Figure 7] 10 is an explanatory diagram showing a state in which the unwelded laminated current collecting portion is pressed against an unwelded current collecting member while being irradiated with laser light, in the method for manufacturing a battery according to the embodiment. FIG. [Figure 8] 10A and 10B are explanatory views showing a state in which a melt-solidified portion is formed by performing laser welding in the battery manufacturing method according to the embodiment. [Figure 9] 10A and 10B are explanatory views showing how positive and negative stacked current collecting parts of the electrode body are connected to positive and negative current collecting members in the manufacturing method of the battery according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to the drawings. A battery (power storage device) 1 of this embodiment is a rectangular (rectangular) sealed lithium ion secondary battery that is installed in vehicles such as hybrid cars, plug-in hybrid cars, and electric vehicles. The battery height direction AH, battery width direction BH, and battery thickness direction CH of the battery 1 are defined as directions shown in FIGS. 1 to 3. The battery 1 is composed of a case 10, an electrode assembly 20 and an electrolyte 5 housed in the case 10, and positive and negative terminals 50 each 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 covered within the case 10 by a bag-shaped insulating holder 7 made of an insulating film.

[0016] The case 10 is a rectangular box made of metal (aluminum in this embodiment). The case 10 is composed of a case body member 11, which is a bottomed, square cylinder with a rectangular annular opening 11c and houses the electrode assembly 20 therein, 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 the 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.

[0017] 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 described together. Each terminal 50 is 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 outside the case 10 and within the insertion hole 10h.

[0018] Each 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] 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). The unwelded laminated current collecting portion 30Z of the electrode body 20 has a rectangular plate shape and extends in the extension direction JH (left-right direction in FIGS. 5 to 9) from the main body 25 of the electrode body 20. In this embodiment, the thickness of the unwelded laminated current collecting portion 30Z is 1.0 mm when pressed in the stacking direction SH.

[0024] 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, and has a planar opposing surface 41 that faces the unwelded laminated current collecting part 30Z during welding, and a planar back surface 42 located on the opposite side of the opposing surface 41 and parallel to the opposing surface 41. In this embodiment, the thickness of the unwelded current collecting member 40Z from the opposing surface 41 to the back surface 42 is 1.0 mm. In this embodiment, when the unwelded laminated current collecting part 30Z is stacked on the unwelded current collecting member 40Z, the first direction DH of the unwelded current collecting member 40Z and the orthogonal direction IH (the up-down direction in Figures 5 and 9, the direction perpendicular to the paper surface in Figures 6 to 8) of the unwelded laminated current collecting part 30Z coincide, and the second direction EH of the unwelded current collecting member 40Z and the extension direction JH of the unwelded laminated current collecting part 30Z coincide.

[0025] The unwelded current collecting member 40Z also has a pair of ridges 46 protruding from the opposing surface 41. These ridges 46 extend in the first direction DH from one end to the other end of the unwelded current collecting member 40Z in the first direction DH at a predetermined distance from each other at the center of the unwelded current collecting member 40Z in the second direction EH. Each ridge 46 has a flat top surface 46m. In this embodiment, the dimensions of each ridge 46 at the opposing surface 41 are 1.3 mm in width (dimension in the second direction EH), 0.5 mm in height, and 5.0 mm in length (dimension in the first direction DH).

[0026] A gas discharge groove 45 is defined between these ridge portions 46. This gas discharge groove 45 extends in the first direction DH from one end of the unwelded current collecting member 40Z in the first direction DH to the other end in the first direction DH at the center of the second direction EH along the ridge portions 46. In this embodiment, the dimensions of the gas discharge groove 45 are: width at the opposing surface 41, i.e., bottom width (dimension in the second direction EH) 0.4 mm, depth 0.5 mm, and length (dimension in the first direction DH) 5.0 mm.

[0027] The facing surface 41 of the unwelded current collecting member 40Z also includes a pair of outer facing surface portions 41d located on both outer sides in the arrangement direction FH (which coincides with the second direction EH in the first embodiment) of the pair of ridge portions 46. Each outer facing surface portion 41d is a flat surface and extends in the first direction DH along the ridge portion 46 from one end of the unwelded current collecting member 40Z in the first direction DH to the other end.

[0028] The laser welding step S2 includes a placement step S20, a bonding step S21, and a melting and solidifying step S22, which are carried out in this order (see FIG. 4). In the arrangement step S20, the unwelded laminated current collecting part 30Z is stacked in the stacking direction SH on the opposing surface 41 of the unwelded current collecting member 40Z, and the unwelded laminated current collecting part 30Z is bridged between a pair of protruding portions 46 of the unwelded current collecting member 40Z. Then, the unwelded laminated current collecting part 30Z is provided with a bridge portion 35 that bridges between the protruding portions 46, and a pair of outer portions 36 that are located on both outer sides of the bridge portion 35 in the arrangement direction FH and overlap a pair of outer opposing surface portions 41d of the opposing surface 41 of the unwelded current collecting member 40Z (see FIGS. 5 to 7).

[0029] Then, in the adhesion process S21, a pair of pressing jigs PJ are placed on top of a pair of outer regions 36 of the unwelded laminated current collecting part 30Z. Each pressing jig PJ is rectangular and has a flat pressing surface PJm. Next, the pair of pressing jigs PJ press the pair of outer regions 36 of the unwelded laminated current collecting part 30Z against a pair of outer opposing surface portions 41d of the opposing surface 41 of the unwelded current collecting member 40Z. Then, a pair of bridging ends 35t on one side FH1 and the other side FH2 in the arrangement direction FH of the bridging region 35 of the unwelded laminated current collecting part 30Z are pressed against the protruding strip portions 46, respectively. At the same time, tension Ta in the arrangement direction FH is applied to the foil bridge portions 21ra included in the bridge portion 35 of each foil collecting portion 21r constituting the unwelded stacked current collecting portion 30Z, so that these foil bridge portions 21ra are tightly attached to each other in the stacking direction SH.

[0030] This reduces the amount of gas present in the bridging region 35 of the unwelded laminated current collecting part 30Z. Because the pressing jig PJ has a flat pressing surface PJm, in the adhesion step S21, this flat pressing surface PJm presses the outer region 36 of the unwelded laminated current collecting part 30Z against the flat outer opposing surface 41d of the unwelded current collecting member 40Z. In addition, because the protruding strip portion 46 has a flat top surface 46m, in the adhesion step S21, the bridging end 35t of the bridging region 35 is pressed against this flat top surface 46m.

[0031] Subsequently, in the melting and solidifying step S22, laser light LB is irradiated from above the unwelded laminated current collecting part 30Z 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 with the first portion 33, and then solidified 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 embodiment, a YAG laser is used.

[0032] In this embodiment, the first portion 33 of the unwelded laminated current collecting portion 30Z to be melted by the laser beam LB is a central portion 35e of the bridging portion 35, excluding portions of both ends in the arrangement direction FH. This first portion 33 (central portion 35e) is a portion that extends in the orthogonal direction IH and includes the entire stacking direction SH. In addition, the second portion 43 of the unwelded current collecting member 40Z to be melted by the laser light LB is a portion of the unwelded current collecting member 40Z that overlaps with the first portion 33 of the unwelded laminated current collecting part 30Z and extends in the first direction DH, and is a portion consisting of the inner portion 46c of each convex strip portion 46 in the arrangement direction FH and the bottom portion 47 that forms the bottom surface of the gas discharge groove 45.

[0033] The first portion 33 and the second portion 43 are melted and then solidified to form a melted and solidified portion 38 having a width (dimensions in the extension direction JH and the second direction EH) of 2.0 mm and a length (dimensions in the orthogonal direction IH and the first direction DH) of 4.0 mm. In this embodiment, in the current collecting member 40 after laser welding, portions of the pair of protruding strips 46 remain. Meanwhile, the gas discharge groove 45 has disappeared due to the formation of the melted and solidified portion 38 by laser welding, except for both end portions in the first direction DH.

[0034] 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 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, since the gas discharge groove 45 extends in the first direction DH, gas is discharged to the outside from both sides of the gas discharge groove 45 in the first direction DH.

[0035] 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 the 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. The internal insulating member 55 and the external insulating member 56 are then 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 then arranged. The crimped terminal member 53 is then crimped to form a positive electrode terminal 50 consisting of the internal terminal member 51, the external terminal member 52, and the crimped terminal member 53, and the terminal 50 is fixed to the case lid member 12 while being insulated from the case lid member 12. The negative electrode terminal 50 is also formed in the same manner as the positive electrode terminal 50.

[0036] Next, in a connection 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. Thereafter, the electrode body 20 is wrapped in a bag-shaped insulating holder 7.

[0037] 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.

[0038] In the manufacturing method of the battery 1 according to this embodiment, a pair of ridges 46 that form the gas discharge grooves 45 are pre-formed on the unwelded current collecting member 40Z before welding. Then, in the bonding step S21 of the laser welding step S2, the pair of outer regions 36 of the unwelded laminated current collecting part 30Z are pressed against a pair of outer facing surface portions 41d of the facing surface 41 of the unwelded current collecting member 40Z, and the pair of bridging ends 35t of the bridging portion 35 are pressed against the ridges 46. At the same time, tension Ta in the arrangement direction FH is applied to the foil bridging portions 21ra included in the bridging portion 35 of each foil current collecting portion 21r that constitutes the unwelded laminated current collecting part 30Z, thereby closely bonding the foil bridging portions 21ra to each other in the stacking direction SH. This reduces the amount of gas present in the bridging portion 35 of the unwelded laminated current collecting part 30Z. Thereafter, in the melt-solidification step S22, at least a part of the bridge portion 35 of the unwelded laminated current collecting part 30Z is made into the first portion 33, and at least a part of each of the protruding strip portions 46 of the unwelded current collecting member 40Z is made into the second portion 43, and these portions 33, 43 are melted while gas generated from these portions 33, 43 is discharged to the outside through the gas discharge groove 45, thereby forming the melt-solidified portion 38. As a result, the occurrence of blowholes in the melt-solidified portion 38 can be suppressed.

[0039] Furthermore, in this embodiment, the pair of protruding portions 46 of the unwelded current collecting member 40Z have flat top surfaces 46m, and in the adhesion step S21, the pair of bridging ends 35t of the bridging region 35 of the unwelded laminated current collecting part 30Z are pressed against these flat top surfaces 46m. Therefore, it is possible to reliably prevent damage such as cracks from occurring in the portions of the foil current collecting part 21r that form the bridging ends 35t due to pressing against the protruding portions 46. In this embodiment, the pair of outer facing surfaces 41d of unwelded current collecting member 40Z are flat, and in the adhesion step S21, the pair of outer regions 36 of unwelded laminated current collecting part 30Z are pressed against the pair of flat outer facing surfaces 41d of unwelded current collecting member 40Z by the flat pressing surfaces PJm of pressing jig PJ. Therefore, the outer regions 36 can be appropriately pressed against the outer facing surfaces 41d of unwelded current collecting member 40Z without causing damage such as cracks in the portions of foil current collecting part 21r that form the outer regions 36.

[0040] Although the present invention has been described above in accordance with the embodiments, it goes without saying that the present invention is not limited to the embodiments and can be modified and applied as appropriate within the scope of the invention. For example, while the embodiment illustrates the battery 1 including a single electrode body 20, 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. Alternatively, one positive and one negative current collecting member may be prepared, and multiple stacked current collecting parts for positive electrodes may be welded to one current collecting member for the positive electrode, and multiple stacked current collecting parts for negative electrodes may be welded to one current collecting member for the negative electrode. In addition, in the embodiment, a laminated electrode body is exemplified as the electrode body, but this is not limited to this, and the electrode body may also be a flat wound type in which positive and negative strip-shaped electrode plates are wound in a flat shape with a pair of strip-shaped separators interposed therebetween.

[0041] In the embodiment, 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 may be used as appropriate. In the embodiment, the battery 1 is exemplified as having the positive electrode current collecting member 40 connected to the positive electrode terminal 50 of the battery 1 and the negative electrode current collecting member 40 connected to the negative electrode terminal 50 of the battery 1, 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]

[0042] 1. Battery (energy storage device) 10 cases 20 Electrode body 21 Electrode plate 21r Foil current collector 21ra Foil Transfer Section 22 Electrode foil 30 Laminated current collector 30Z Unwelded laminated current collector 33 Part 1 35 Bridge section 35t bridge end 36 External part 38 Melting and solidification section 40 Current collecting member 40Z Unwelded current collecting member 41 Opposite surface 41d Outside facing surface part 43 Part 2 45 Gas exhaust groove 46 Convex portion 46m flat top surface 50 terminals FH (ridge) arrangement direction FH1 (column direction) one side FH2 (other side in row direction) SH (Laminated current collector) stacking direction PJ pressing jig PJm Pressing surface Ta tension S2 laser welding process S20 placement process S21 Adhesion process S22 Melting and solidification 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 is an opposing surface facing the unwelded laminated current collecting portion; a pair of ridges protruding from the opposing surfaces, the space between which forms a gas discharge groove; the opposing surfaces include a pair of outer opposing surface portions located on both outer sides of the pair of protruding portions in an arrangement direction, The laser welding process includes: an arrangement process in which the unwelded laminated current collecting portion is bridged between the pair of convex rib portions of the unwelded current collecting member to provide a bridge portion that bridges between the convex rib portions and a pair of outer portions that are located on both outer sides of the bridge portion in the arrangement direction and overlap the pair of outer opposing surface portions of the unwelded current collecting member; a contacting process in which a pair of outer portions of the unwelded laminated current collecting portion are pressed against a pair of outer opposing surface portions of the unwelded current collecting member, a pair of bridging end portions on one side and the other side in the arrangement direction of the bridging portion are pressed against the protruding rib portions, and tension is applied in the arrangement direction to foil bridging portions included in the bridging portions of each of the foil current collecting portions constituting the unwelded laminated current collecting portion, thereby bringing the foil bridging portions into close contact with each other in the stacking direction; a melting and solidifying step of: defining at least a part of the bridge portion of the unwelded laminated current collecting member as the first portion; defining at least a part of each of the protruding strip portions of the unwelded current collecting member as the second portion; melting the first portion and the second portion; and discharging gas generated from these portions to the outside through the gas discharge groove; and then forming the melted and solidified portion. A method for manufacturing an electricity storage device.

2. A method for manufacturing the electricity storage device according to claim 1, The pair of protruding portions of the unwelded current collecting member each have a flat top surface, The contacting step includes pressing a pair of the bridging end portions of the bridging portion of the unwelded laminated current collector against the flat top surfaces of the pair of the protruding portions, respectively. A method for manufacturing an electricity storage device.

3. A method for manufacturing the electricity storage device according to claim 1 or 2, comprising: The pair of outer facing surfaces of the unwelded current collecting member are each flat, The contact step includes pressing the pair of outer portions of the unwelded laminated current collecting part against the pair of flat outer facing surfaces of the unwelded current collecting member using a pair of flat pressing surfaces of a pressing jig. A method for manufacturing an electricity storage device.

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