Method for manufacturing power storage device

Abstract

To provide a method of manufacturing a power storage device capable of suppressing generation of blowholes in a melt-solidified part when laser-welding an unwelded laminated current collecting part to an unwelded current collecting member.SOLUTION: The method includes a pressing step S2 and a laser-welding step S3. In the pressing step S2, the pressed part 31 of the unwelded laminated collector part 30Z is pressed by a projecting part PJt of a translucent pressing tool PJ, and the foil-collector part 21r of the pressed part 31 are adhered to each other, and the degree of adhesion of the foil-collector part 21r of the pressed peripheral part 32 is made lower than the pressed part 31. In the laser-welding step S3, the laser beam LB is transmitted through the protrusion PJt of the light-transmissive pressing jig PJ to irradiate the unwelded laminated collector portion 30Z, and the gas generated from the first portion 33 to be melted is released to the pressed surrounding portion 32 to form the melted and solidified portion 38.SELECTED DRAWING: Figure 6

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 a foil current collector with the exposed electrode foil of the positive electrode plate and a negative electrode laminated current collector formed by laminating a foil current collector with the exposed electrode foil of the negative electrode plate. 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 to the outside of the battery to serve as the positive electrode terminal, and the negative electrode current collector itself extends to the outside of 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 then the unwelded laminated current collector is pressed against the unwelded current collecting member using a light-transmitting pressing jig that transmits laser light. In this state, laser light is irradiated onto the unwelded laminated current collector through the light-transmitting pressing jig 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 of the electrode assembly is welded to the current collecting member. Related prior art documents include, for example, Patent Document 1 (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. 2023-103708 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 molten and solidified portion welded in this manner. Even when an unwelded laminated current collector is pressed against an unwelded current collecting member using a light-transmitting pressing jig with a flat pressing surface, gaps still exist between the multiple foil current collecting portions that form the first portion to be melted by the laser beam in the unwelded laminated current collecting portion, and gas such as air remains in these gaps. For this reason, the gas in the gaps has no place to escape during laser welding and is trapped in the molten and solidified portion, which is thought to result in 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 melted and solidified portion when the unwelded laminated current collecting portion of an electrode body is pressed against an unwelded current collecting member with a translucent pressing jig and the unwelded laminated current collecting portion is laser welded 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 manufacturing method of 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 manufacturing method including: a pressing step of stacking an unwelded current collecting member before welding, the unwelded laminated current collecting portion before welding, and a translucent pressing jig that transmits laser light in this order in the lamination direction, and pressing the unwelded laminated current collecting portion toward the unwelded current collecting member with the translucent pressing jig; and a laser beam passing through the translucent pressing jig and irradiating the unwelded laminated current collecting portion 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 solidifying the melted and solidified portion, thereby melting the laminated current collecting portion against the current collecting member. and a laser welding step of welding a laminated foil to a material, wherein the translucent pressing jig has a convex portion that protrudes toward the unwelded laminated current collecting part when the jig is placed on the unwelded laminated current collecting part, the pressing step pressing the pressed portion of the unwelded laminated current collecting part with the convex portion of the translucent pressing jig to tightly adhere the foil current collecting parts stacked at the pressed portion and to reduce the degree of adhesion between the foil current collecting parts stacked in a pressed peripheral portion of the unwelded laminated current collecting part around the pressed portion compared to the pressed portion, and the laser welding step irradiating the laser light through the convex portion of the translucent pressing jig to at least a part of the pressed portion of the unwelded laminated current collecting part to form the first portion, and melting the first portion and the second portion while allowing gas generated from the first portion to escape to the pressed peripheral portion, thereby forming the molten and solidified portion.

[0008] In the above-described method for manufacturing an electricity storage device, in the pressing step, the convex portion of the transparent pressing jig presses the pressed portion of the unwelded laminated current collecting portion to tightly contact the foil current collecting portions of the pressed portion, thereby reducing the amount of gas present in the pressed portion. Meanwhile, in the pressed peripheral portion around the pressed portion, the degree of contact between the foil current collecting portions is reduced, making it easier for gas in the pressed portion to escape to the pressed peripheral portion. Therefore, in the laser welding step, gas generated from the first portion of the unwelded laminated current collecting portion can escape to the pressed peripheral portion and even be discharged to the outside, thereby suppressing the occurrence of blowholes 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. Examples of materials for the "transparent pressing jig" include synthetic quartz glass, borosilicate glass, crystallized glass, barium fluoride, calcium fluoride, and sapphire. Examples of the "protrusion" of the light-transmitting pressing jig include a spherical protrusion such as a hemispherical protrusion having a hemispherical tip surface, and a semi-cylindrical protrusion having a semi-cylindrical tip surface. Further examples of the protrusion include a columnar protrusion having a cylindrical or polygonal prism shape having a flat tip surface, and a truncated cone or polygonal truncated pyramid shape having a flat tip surface.

[0010] (2) In the method for producing an electricity storage device according to (1), the tip end surface of the convex portion of the light-transmitting pressing jig may have a rounded convex shape without corners.

[0011] In the manufacturing method of the above-mentioned energy storage device, the tip surface of the convex portion of the translucent pressing jig has a rounded convex shape with no corners, so that when the tip surface of the convex portion of the translucent pressing jig is used to press the pressed portion of the unwelded laminated current collecting part, damage such as cracks can be prevented from occurring in the part of the foil current collecting part that forms the pressed portion. In addition, examples of "the tip surface of the convex portion has a rounded convex shape without corners" include when the tip surface of the convex portion has a convex shape that forms part of a spherical surface, such as a hemispherical surface, when the tip surface of the convex portion has a convex shape that forms part of a cylindrical surface, such as a semi-cylindrical surface, and when the entire tip surface of the convex portion has no corners and is composed of a gently curved surface.

[0012] (3) In the method for manufacturing an electric storage device according to (2), the tip surface of the convex portion of the light-transmitting pressing jig may have a convex shape that forms a part of a spherical surface or a part of a cylindrical surface.

[0013] In the above-described method for manufacturing an electricity storage device, in the pressed portion of the unwelded laminated current collecting part, in the portion pressed near the center of the tip surface of the convex portion (when the tip surface is part of a spherical surface) or the center line (when the tip surface is part of a cylindrical surface), the foil current collecting part constituting this portion can be pressed strongly to increase the degree of adhesion. On the other hand, in the pressed portion of the unwelded laminated current collecting part that is pressed around the tip surface of the convex portion, i.e., in the portion of the pressed portion close to the pressed peripheral portion, the foil current collecting part constituting this portion can be pressed relatively weakly to gradually approach the degree of adhesion between the foil current collecting parts constituting the pressed peripheral portion. Therefore, in the pressing process and laser welding process, gas in the pressed portion of the unwelded laminated current collecting part can be easily released, particularly to the pressed peripheral portion of the unwelded laminated current collecting part, thereby more effectively suppressing the occurrence of blowholes in the melted and solidified portion. [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]1 is an explanatory diagram showing, viewed from above, the state in which an unwelded laminated current collecting portion of an electrode body is placed on an unwelded current collecting member, and then a translucent pressing jig is placed on top and pressed, in relation to a manufacturing method of a battery according to an embodiment. [Figure 6] FIG. 10 is an explanatory diagram showing a method for manufacturing a battery according to an embodiment, in which a convex portion of a translucent pressing jig is used to press an unwelded laminated current collecting portion against an unwelded current collecting member, while laser light is transmitted through the convex portion of the translucent pressing jig and irradiated onto the unwelded laminated current collecting portion. [Figure 7] 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 8] 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. [Figure 9] 7A to 7C are explanatory views corresponding to FIG. 6 and relating to a method for manufacturing a battery according to a modified embodiment of the present invention. [Figure 10] 8A to 8C are explanatory views corresponding to FIG. 7 and relating to a method for manufacturing a battery according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Embodiment) 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] Case 10 is made of metal (aluminum in this embodiment) and has a rectangular box shape. Case 10 is composed of case body member 11, which is a square cylindrical body with a bottom and has a rectangular opening 11c, and case lid member 12, which is a rectangular plate and closes opening 11c of case body member 11. Opening 11c of case body member 11 and peripheral edge 12f of case lid member 12 are hermetically welded along their entire periphery. Case lid member 12 is provided with safety valve 10w, which ruptures and opens when the internal pressure of case 10 exceeds a valve opening pressure. Case lid member 12 is also provided with 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 of the case lid member 12, 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, which will be 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] Each 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 to the upper side 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, 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 the positive electrode 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 8). 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, unwelded current collecting members 40Z before welding for positive and negative electrodes are prepared, and a pressing process S2 and a laser welding process S3 (see Figure 4) are performed to weld the unwelded laminated current collecting portion 30Z of the positive electrode of the electrode body 20 before welding to the unwelded current collecting member 40Z for positive electrodes, and weld the unwelded laminated current collecting portion 30Z of the negative electrode of the electrode body 20 before welding to the unwelded current collecting member 40Z for negative electrodes (see Figures 5 to 8). First, in the pressing process S2, the unwelded current collecting member 40Z, the unwelded laminated current collecting portion 30Z, and a translucent pressing jig PJ through which the laser light LB passes are stacked in this order in the stacking direction SH, and the translucent pressing jig PJ is used to press the unwelded laminated current collecting portion 30Z toward the unwelded current collecting member 40Z.

[0024] The unwelded current collecting member 40Z has a rectangular plate shape extending in a first member direction DH (the up-down direction in FIGS. 5 and 8, the direction perpendicular to the paper surface in FIGS. 6 and 7) and a second member direction EH (the left-right direction in FIGS. 5 to 8) perpendicular thereto, and has a planar overlapping surface 41 that overlaps the unwelded laminated current collecting part 30Z, and a planar back surface 42 located opposite to the overlapping surface 41 and parallel to the overlapping surface 41. In this embodiment, the thickness of the unwelded current collecting member 40Z is 1.0 mm. The unwelded laminated current collecting portion 30Z of the electrode body 20 is a rectangular plate-like portion that extends in the extension direction JH (left-right direction in FIGS. 5 to 8) 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 lamination direction SH.

[0025] The light-transmitting pressing jig PJ is made of synthetic quartz glass. The light-transmitting pressing jig PJ consists of a base PJa and one protrusion PJt, and extends in a first jig direction FH (the up-and-down direction in FIGS. 5 and 8, and the direction perpendicular to the paper surface in FIGS. 6 and 7). Of these, the base PJa is a rectangular plate extending in the first jig direction FH and a second jig direction GH perpendicular thereto (the left-right direction in FIGS. 5 to 8). On the other hand, the protrusion PJt has a shape that protrudes from the base PJa toward the unwelded laminated current collecting part 30Z when the light-transmitting pressing jig PJ is placed on the unwelded laminated current collecting part 30Z. In this embodiment, the convex portion PJt is a convex rib portion that forms part of a cylinder, and the tip surface PJm of the convex portion PJt that contacts the unwelded laminated current collecting portion 30Z has a rounded convex shape without corners, and further has a convex shape that forms part of a cylindrical surface.

[0026] In this embodiment, when the unwelded current collecting member 40Z, the unwelded stacked current collecting portion 30Z, and the translucent pressing jig PJ are stacked, the first member direction DH of the unwelded current collecting member 40Z, the perpendicular direction IH perpendicular to the extension direction JH of the unwelded stacked current collecting portion 30Z, and the first jig direction FH of the translucent pressing jig PJ coincide, and the second member direction EH of the unwelded current collecting member 40Z, the extension direction JH of the unwelded stacked current collecting portion 30Z, and the second jig direction GH of the translucent pressing jig PJ coincide.

[0027] In the pressing step 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 a light-transmitting pressing jig PJ is then placed on top of the unwelded laminated current collecting part 30Z. One of the protrusions PJt of the light-transmitting pressing jig PJ presses the pressed portion 31 of the unwelded laminated current collecting part 30Z toward the unwelded current collecting member 40Z. In this embodiment, the pressed portion 31 is a rectangular parallelepiped portion that has a constant width (dimension in the extension direction JH) and extends in the orthogonal direction IH.

[0028] The laminated foil current collecting portions 21r in the pressed portion 31 of the unwelded laminated current collecting portion 30Z are brought into tight contact with each other, and the degree of contact between the laminated foil current collecting portions 21r in the pressed peripheral portion 32 of the unwelded laminated current collecting portion 30Z around the pressed portion 31 is made lower than the degree of contact between the foil current collecting portions 21r in the pressed portion 31. In this embodiment, the pressed peripheral portions 32 are portions of the unwelded laminated current collecting portion 30Z that are located on both outer sides of the extension direction JH of the pressed portion 31 and extend in the orthogonal direction IH. By performing the pressing step S2 in this manner, gas within the pressed portion 31 of the unwelded laminated current collecting portion 30Z can be released to the pressed peripheral portion 32 where the foil current collecting portions 21r are less tightly contacted with each other.

[0029] Subsequently, in the laser welding step S3, a laser beam LB is irradiated onto the unwelded laminated current collecting part 30Z from above the light-transmitting pressing jig PJ, passing through the light-transmitting pressing jig PJ, to melt the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 43 of the unwelded current collecting member 40Z that overlaps the first portion 33, and then solidifies to form a melted and solidified portion 38, thereby welding the laminated current collecting part 30 to the current collecting member 40 (see FIGS. 7 and 8 ). More specifically, the laser beam LB is irradiated onto a part of the pressed portion 31 of the unwelded laminated current collecting part 30Z, passing through the protrusion PJt of the light-transmitting pressing jig PJ, to form the first portion 33. Then, the first portion 33 and the second portion 43 are melted while the gas generated from the first portion 33 is released to the pressed peripheral portion 32 where the foil current collecting portions 21r are less closely adhered to each other, and then the melt-solidified portion 38 is formed. In this embodiment, a YAG laser is used.

[0030] In this embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z to be melted by the laser beam LB is the center portion in the extending direction JH of the pressed portion 31 of the unwelded laminated current collecting part 30Z. This first portion 33 is a portion that extends in the orthogonal direction IH like the pressed portion 31, and is a portion that includes the entire stacking direction SH (the entire thickness). The second portion 43 of the unwelded current collecting member 40Z to be melted by the laser beam 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 member direction DH. By melting these first portion 33 and second portion 43 and then solidifying them, a molten and solidified portion 38 is formed having a width (dimension in the extension direction JH and second member direction EH) of 2.0 mm and a length (dimension in the perpendicular direction IH and first member direction DH) of 4.0 mm.

[0031] Separately, in a terminal fixing process S4 (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 on the case lid member 12, and the internal terminal member 51, the external terminal member 52, and the crimped terminal member 53 are arranged and crimped, thereby forming a positive electrode terminal 50 consisting of the internal terminal member 51, the external terminal member 52, and the crimped terminal member 53, and fixing this terminal 50 to the case lid member 12 while keeping it insulated. The negative electrode terminal 50 is also formed in the same manner as the positive electrode terminal 50.

[0032] Next, in a connecting step S5 (see FIG. 4 ), the positive and negative current collecting members 40 connected to the electrode body 20 in the laser welding step S3 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.

[0033] Next, in the case formation process S6 (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 S7, 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 S8, 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.

[0034] In the manufacturing method of the battery 1 of this embodiment, in the pressing step S2, the protrusions PJt of the transparent pressing jig PJ press the pressed portion 31 of the unwelded laminated current collecting part 30Z to tightly contact the foil current collecting portions 21r of the pressed portion 31, thereby reducing the amount of gas present in the pressed portion 31. On the other hand, in the pressed peripheral portion 32 surrounding the pressed portion 31, the degree of contact between the foil current collecting portions 21r is reduced, making it easier for gas in the pressed portion 31 to escape to the pressed peripheral portion 32. Therefore, in the laser welding step S3, gas generated from the first portion 33 of the pressed portion 31 of the unwelded laminated current collecting part 30Z can escape to the pressed peripheral portion 32 and further be discharged to the outside, thereby suppressing the occurrence of blowholes in the melted and solidified portion 38.

[0035] Furthermore, in this embodiment, the tip surface PJm of the convex portion PJt of the translucent pressing jig PJ has a rounded convex shape with no corners, so when the tip surface PJm of the convex portion PJt of the translucent pressing jig PJ presses the pressed portion 31 of the unwelded laminated current collecting portion 30Z, it is possible to prevent damage such as cracks from occurring in the portion of the foil current collecting portion 21r that forms the pressed portion 31. Furthermore, the tip surface PJm of the protrusion PJt has a convex shape that forms a part of a cylindrical surface. Therefore, in the pressed portion 31 of the unwelded laminated current collecting part 30Z, the foil current collecting part 21r constituting this portion is pressed strongly at a portion pressed near the center line of the tip surface PJm of the protrusion PJt, thereby increasing the degree of adhesion. On the other hand, in the pressed portion 31 of the unwelded laminated current collecting part 30Z, the foil current collecting part 21r constituting this portion is pressed around the tip surface PJm of the protrusion PJt, i.e., the portion of the pressed portion 31 close to the pressed peripheral portion 32, the foil current collecting part 21r constituting this portion is pressed relatively weakly, thereby gradually bringing the degree of adhesion closer to the degree of adhesion between the foil current collecting parts 21r constituting the pressed peripheral portion 32. Therefore, in each of the pressing process S2 and the laser welding process S3, the gas in the pressed portion 31 of the unwelded laminated current collecting portion 30Z can be particularly easily released to the pressed surrounding portion 32 of the unwelded laminated current collecting portion 30Z, and the occurrence of blowholes in the molten and solidified portion 38 can be more effectively suppressed.

[0036] (Variations) Next, a modified embodiment of the above embodiment will be described (see FIGS. 9 and 10). Descriptions of parts similar to those of the embodiment will be omitted or simplified. In the battery 100 of this modified embodiment, the current collecting member 140 and the unwelded current collecting member 140Z have different shapes from those of the current collecting member 40 and the unwelded current collecting member 40Z of the first embodiment. Specifically, the unwelded current collecting member 140Z of this modified embodiment is a rectangular plate having a superposed surface 141 and a back surface 142. However, this unwelded current collecting member 140Z has a groove 145 formed on the back surface 142 of the unwelded current collecting member 140Z and extending in the first member direction DH in a second portion 143 to be melted by laser welding. In this modified embodiment, the second portion 143 of the unwelded current collecting member 140Z to be melted by laser light LB is the entire thickness direction of a central portion of a bottom portion 147 forming the bottom surface of the above-mentioned groove 145.

[0037] In the laser welding step S3 of this modified embodiment, when 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, gas generated from these portions 33, 143 is also discharged to the outside from the above-mentioned recessed groove 145. Therefore, it is possible to particularly effectively prevent blowholes from occurring in the melt-solidified portion 138 that is formed by subsequent solidification. Other parts that are the same as those in the embodiment provide the same functions and effects as those in the embodiment.

[0038] Although the present invention has been described above in accordance with embodiments and modified forms, it goes without saying that the present invention is not limited to the embodiments and modified forms, and can be appropriately modified and applied within the scope that does not deviate from the gist of the present invention. For example, in the embodiments and the like, the battery 1 is illustrated as having a single electrode body 20, but the present invention is not limited to this. The battery may also have multiple electrode bodies. In this case, multiple positive and negative current collecting members may be prepared, and the positive and negative laminated 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 positive electrode laminated current collecting parts may be welded to one positive electrode current collecting member, and multiple negative electrode laminated current collecting parts may be welded to one negative electrode current collecting member. In addition, in the embodiments, a laminated electrode body has been 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.

[0039] In the embodiment, the laser welding step S3 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 embodiments and the like, the battery 1 and the like have been 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]

[0040] 1,100 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 31 (Unwelded laminated current collector) pressed part 32 (Unwelded laminated current collector) pressed peripheral part 33 Part 1 38,138 Melting and solidification section 40,140 Current collecting member 40Z, 140Z Unwelded current collecting member 43,143 2nd part 50 terminals SH (Laminated current collector) stacking direction LB laser light PJ Translucent Pressing Jig PJt (Translucent pressing member) convex part PJm (protruding part) tip surface S2 Pressing process S3 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: a pressing step of stacking an unwelded current collecting member before welding, an unwelded laminated current collecting portion before welding, and a light-transmitting pressing jig that transmits laser light in this order in the stacking direction, and pressing the unwelded laminated current collecting portion toward the unwelded current collecting member with the light-transmitting pressing jig; a laser welding process in which laser light is transmitted through the translucent pressing jig and irradiated onto the unwelded laminated current collecting portion 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 solidifies the melted and solidified portion to form a molten and solidified portion, thereby welding the laminated current collecting portion to the current collecting member, the translucent pressing jig has a convex portion that protrudes toward the unwelded laminated current collecting portion when the translucent pressing jig is placed on the unwelded laminated current collecting portion, The pressing step includes: the convex portion of the transparent pressing jig presses the pressed portion of the unwelded stacked current collecting part, so that the foil current collecting parts stacked in the pressed portion are tightly adhered to each other, and the degree of adhesion between the foil current collecting parts stacked in the pressed peripheral portion around the pressed portion of the unwelded stacked current collecting part is made lower than that of the pressed portion, The laser welding process includes: The laser light is transmitted through the convex portion of the light-transmitting pressing jig and irradiated onto at least a part of the pressed portion of the unwelded laminated current collector to form the first portion, and the first portion and the second portion are melted while gas generated from the first portion is released to the pressed surrounding portion, thereby 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 tip surface of the convex portion of the transparent pressing jig has a rounded convex shape without corners. Energy storage device.

3. A method for manufacturing the electricity storage device according to claim 2, The tip surface of the convex portion of the light-transmitting pressing jig has a convex shape that forms a part of a spherical surface or a part of a cylindrical surface. Energy storage device.

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