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 30Z of the collector part is pressed by each projecting part PJt of a translucent pressing jig PJ, and the 30Z of the collector part is brought into close contact with each other at the pressed part 31 and the pressed part 32 of the 21r of the collector part. In the laser-welding step S3, the unwelded laminated collector portion 30Z is irradiated with the laser beam LB through the light-transmitting pressing jig PJ to melt the first portion 33 and the second portion 43, and the gas generated therefrom is discharged to the outside through the gas-discharging recessed groove PJv of the light-transmitting pressing jig PJ 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 flat, 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 member, and gases such as air remain 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 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 an unwelded current collecting member before welding, an unwelded laminated current collecting portion before welding, and a translucent pressing jig that transmits laser light in this order. and a laser welding process in which a laser beam is transmitted through the light-transmitting 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 first portion to form a molten and solidified portion, thereby welding the laminated current collecting portion to the current collecting member. the pressing step presses a plurality of pressed portions of the unwelded laminated current collecting portion with each of the pressed portions of the unwelded laminated current collecting portion, and at pressed portions of the unwelded laminated current collecting portion that are located between the pressed portions and overlap with the gas discharge grooves in the stacking direction, and the laser welding step irradiates the laser light that passes through the translucent pressing jig and at at least a portion of the pressed portions of the unwelded laminated current collecting portion to melt the first portion and the second portion including at least a portion of the pressed portions, and to discharge gas generated from these portions to the outside through the gas discharge grooves, and thereafter the melt-solidified portion is formed.

[0008] The manufacturing method for the above-described electricity storage device uses a translucent pressing jig having multiple ridges that define one or more gas discharge grooves. In the pressing step, each ridge of the translucent pressing jig presses the pressed portion of each unwelded laminated current collector, thereby closely adhering the foil current collector portions of the pressed portion and the pressed portion between the pressed portions of the unwelded laminated current collector. This reduces the amount of gas present in these portions. Furthermore, in the laser welding step, a laser beam is transmitted through the translucent pressing jig and irradiated onto at least a portion of the pressed portion between the pressed portions of the unwelded laminated current collector, melting the first portion of the unwelded laminated current collector and the second portion of the unwelded current collector member. Gas generated from these portions is then discharged to the outside through the gas discharge groove, forming a melted and solidified portion. This prevents 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. Examples of materials for the "transparent pressing jig" include synthetic quartz glass, borosilicate glass, crystallized glass, barium fluoride, calcium fluoride, and sapphire.

[0010] (2) The method for manufacturing an electric storage device according to (1), further comprising the step of: in the laser welding step, melting the first portion of the unwelded laminated current collecting portion by the laser beam, in addition to the pressed portion, also includes a part of the pressed portion. The method may be used as a method for manufacturing an electricity storage device.

[0011] In the manufacturing method of the electricity storage device described above, the unwelded laminated current collecting part is melted not only in the pressed portion but also in part of the pressed portion, i.e., the portion pressed by the ridge portion where the foil current collecting parts are particularly closely adhered to each other, as the first portion to form the melted and solidified portion. Therefore, compared to when only the pressed portion of the unwelded laminated current collecting part is melted as the first portion to form the melted and solidified portion, the occurrence of blowholes can be suppressed.

[0012] (3) In the method for manufacturing an electricity storage device according to (1) or (2), the bottom of the gas discharge groove of the light-transmitting pressing jig may be flat.

[0013] In the above-described method for manufacturing an electricity storage device, the groove bottom of the transparent pressing jig is flat, so that the laser light passing through this groove bottom can reach the unwelded laminated current collecting portion without distortion. Therefore, compared to when the groove bottom is not flat, the unwelded laminated current collecting portion can be melted appropriately to form a melt-solidified portion.

[0014] (4) Further, in the method for manufacturing an electric storage device according to any one of (1) to (3), the unwelded current collecting member may have a component gas exhaust channel at least in the second portion melted by the laser light, and the laser welding process may be a method for manufacturing an electric storage device in which gas generated from the first portion and the second portion is exhausted to the outside through the component gas exhaust channel in addition to the gas exhaust groove.

[0015] In the manufacturing method of the above-described electricity storage device, a component gas exhaust path such as a groove or a through-hole is provided in advance in at least the second portion of the unwelded current collecting member that is to be melted during welding. Then, in the laser welding step, 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 exhausted to the outside not only through the gas exhaust groove of the translucent pressing jig but also through the component gas exhaust path of the unwelded current collecting member, thereby forming a melted and solidified portion. This further effectively prevents blowholes from occurring in the melted and solidified portion.

[0016] Examples of the "component gas exhaust channel" include a surface-side gas exhaust groove provided on the overlapping surface of the unwelded current collecting member where the laminated current collecting portion of the electrode body 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 2 (see FIGS. 9 and 10, etc.), and the gas exhaust through-hole will be described in embodiment 3 (see FIGS. 11 and 12, etc.). A portion of the component gas exhaust channel may remain in the current collecting member after laser welding, or the component gas exhaust channel may not exist in the current collecting member after laser welding due to the formation of a molten and solidified portion by laser welding.

[0017] (5) Further, in the method for manufacturing an electricity storage device described in (4), it is preferable that the unwelded current collecting member has an overlapping surface on which the unwelded laminated current collecting portion is overlapped, and the member gas exhaust path is provided on the overlapping surface of the unwelded current collecting member and is an overlapping surface side gas exhaust groove provided in at least the second portion.

[0018] In the method for manufacturing the electricity storage device described above, the member gas discharge path includes a overlapping surface-side gas discharge groove provided in at least the second portion of the unwelded current collecting member, whereby gas can be appropriately discharged from both the gas discharge groove of the light-transmitting pressing jig and the overlapping surface-side gas discharge groove of the unwelded current collecting member in the laser welding step, thereby forming a melted and solidified portion with no or few blowholes.

[0019] In the method for manufacturing an electricity storage device described in (6) or (4), the unwelded current collecting member preferably has 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 member 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.

[0020] In the method for manufacturing an electricity storage device described above, the member 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, whereby gas can be appropriately discharged from both the gas discharge groove of the transparent pressing jig and the gas discharge through-hole of the unwelded current collecting member in the laser welding step, thereby forming a melted and solidified portion with no or few blowholes. [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] 1 is an explanatory diagram showing, viewed from above, how the unwelded laminated current collecting portion of the electrode body is placed on top of the unwelded current collecting member, and then a translucent pressing jig is placed on top of it to press, in relation to the manufacturing method of the battery according to embodiment 1. [Figure 6] FIG. 10 is an explanatory diagram showing a method for manufacturing a battery according to the first embodiment, in which an unwelded laminated current collecting part is pressed against an unwelded current collecting member by a convex portion of a translucent pressing jig, while laser light is transmitted through the translucent pressing jig and irradiated onto the unwelded laminated current collecting part. [Figure 7] 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 8] 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 9] 7 is an explanatory view corresponding to FIG. 6, relating to a method for manufacturing a battery according to a second embodiment. [Figure 10] 8 is an explanatory view corresponding to FIG. 7, relating to a method for manufacturing a battery according to a second embodiment. [Figure 11]10 is an explanatory diagram corresponding to FIG. 6, relating to a method for manufacturing a battery according to a third embodiment. [Figure 12] 8 is an explanatory diagram corresponding to FIG. 7, relating to a method for manufacturing a battery according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] (Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. A battery (power storage device) 1 of this first 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 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.

[0023] 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 case 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.

[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 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.

[0025] 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, to be 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.

[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] 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.

[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 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).

[0030] 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.

[0031] The unwelded current collecting member 40Z has a rectangular plate shape extending in a first member direction DH (up-down direction in FIGS. 5 and 8, direction perpendicular to the paper surface in FIGS. 6 and 7) and a second member direction EH (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 1, 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 1, the thickness of the unwelded laminated current collecting portion 30Z is 1.0 mm when pressed in the stacking direction SH.

[0032] The transparent pressing jig PJ is made of synthetic quartz glass. The transparent pressing jig PJ consists of a base PJa and two (a pair of) parallel ridges PJt spaced a predetermined distance apart, extending in a first jig direction FH (the up-down direction in FIGS. 5 and 8, the direction perpendicular to the paper surface in FIGS. 6 and 7). 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). The pair of ridges PJt protrude from the base PJa toward the unwelded laminated current collecting part 30Z when the transparent pressing jig PJ is placed on the unwelded laminated current collecting part 30Z, and a gas discharge groove PJv extending in the first jig direction FH is defined between the ridges PJt. The gas discharge groove PJv of the transparent pressing jig PJ has a groove bottom PJb formed in a flat plate shape. In the first embodiment, the gas discharge groove PJv has a width (dimension in the second jig direction GH) of 1.0 mm and a depth of 0.3 mm.

[0033] In this embodiment 1, 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.

[0034] 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 transparent pressing jig PJ is then placed on top of the unwelded laminated current collecting part 30Z. A pair of ridges PJt of the transparent pressing jig PJ press two (a pair) of pressed portions 31 of the unwelded laminated current collecting part 30Z toward the unwelded current collecting member 40Z. The foil current collecting parts 21r of the unwelded laminated current collecting part 30Z are then tightly attached to each other at each pressed portion 31 and at the pressed portion 32 located between them. By performing this pressing step S2, it is possible to reduce gas in the pressed portion 31 and the pressed portion 32 of the unwelded laminated current collecting part 30Z.

[0035] Each pressed portion 31 is a portion of the unwelded laminated current collecting portion 30Z that is pressed by the protruding strip portion PJt of the transparent pressing jig PJ, and is a rectangular parallelepiped portion that extends in the orthogonal direction IH with a constant width (dimension in the extension direction JH). The inter-pressed portion 32 is a portion of the unwelded laminated current collecting portion 30Z that is located between a pair of pressed portions 31 and overlaps with the gas discharge groove PJv of the transparent pressing jig PJ in the stacking direction SH. This inter-pressed portion 32 is also a rectangular parallelepiped portion that extends in the orthogonal direction IH with a constant width (dimension in the extension direction JH).

[0036] Next, in the laser welding process S3, laser light LB is irradiated from above the translucent pressing jig PJ, passing through the translucent pressing jig PJ and onto the unwelded laminated current collecting part 30Z, melting 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 with the first portion 33, and then solidifying them to form a molten and solidified portion 38, thereby welding the laminated current collecting part 30 to the current collecting member 40 (see Figures 7 and 8).

[0037] Specifically, laser light LB is transmitted through the groove bottom PJb of the transparent pressing jig PJ and irradiated onto the central portion of the unwelded laminated current collecting member 30Z in the extension direction JH of the pressed inter-section 32. In this embodiment, a YAG laser is used. The first portion 33, including the central portion of the pressed inter-section 32 in the extension direction JH, 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 PJv of the transparent pressing jig PJ, which overlaps with the pressed inter-section 32 in the stacking direction SH. The melted and solidified portion 38 is then formed. Because the gas discharge groove PJv extends in the first jig direction FH, gas is discharged to the outside from both sides of the gas discharge groove PJv in the first jig direction FH. This laser welding prevents blowholes from occurring in the melted and solidified portion 38.

[0038] In the first embodiment, the first portion 33 of the unwelded laminated current collecting part 30Z to be melted by the laser light LB is the entire pressed portion 32 and a portion 31c of each pressed portion 31 located near the pressed portion 32. The first portion 33 is a portion extending in the orthogonal direction IH and including the entire unwelded laminated current collecting part 30Z in the stacking direction SH (the entire thickness). Furthermore, the second portion 43 of the unwelded current collecting member 40Z to be melted by the laser light LB is a portion (roughly a semi-cylindrical portion) of the unwelded current collecting member 40Z on the overlapping surface 41 side 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The manufacturing method for battery 1 of Embodiment 1 uses a transparent pressing jig PJ having multiple ridges PJt that form gas release grooves PJv. In the pressing step S2, each ridge PJt of the transparent pressing jig PJ presses each pressed portion 31 of unwelded laminated current collecting part 30Z, thereby tightly adhering foil current collecting parts 21r of each pressed portion 31 and the inter-pressed portions 32 located between them in unwelded laminated current collecting part 30Z. This reduces the amount of gas present in these portions 31, 32. Furthermore, in the laser welding step S3, laser light LB is transmitted through the transparent pressing jig PJ and irradiated onto a part of the pressed portion 32 of the unwelded laminated current collecting part 30Z, melting the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 43 of the unwelded current collecting member 40Z, and gas generated from these portions 33, 43 is discharged to the outside through the gas discharge groove PJv to form the melted and solidified portion 38. As a result, the occurrence of blowholes in the melted and solidified portion 38 can be suppressed.

[0043] Furthermore, in the first embodiment, not only the pressed portions 32 of the unwelded laminated current collecting part 30Z but also a part (portion 31c) of each pressed portion 31, i.e., the portion pressed by each ridge portion PJt and where the foil current collecting parts 21r are in particularly close contact with each other, is melted as the first portion 33 to form the melted and solidified portion 38. Therefore, compared to the case where only the pressed portions 32 of the unwelded laminated current collecting part 30Z are melted as the first portion to form the melted and solidified portion 38, the occurrence of blowholes can be suppressed. Furthermore, in the present embodiment 1, the groove bottom PJb of the transparent pressing jig PJ is flat, so that the laser light LB passing through this groove bottom PJb can reach the unwelded laminated current collecting part 30Z without distortion. Therefore, compared to when the groove bottom PJb is not flat, the unwelded laminated current collecting part 30Z can be melted appropriately to form the melt-solidified part 38.

[0044] (Embodiment 2) Next, a second embodiment will be described (see FIGS. 9 and 10). Descriptions of parts similar to those of the first embodiment will be omitted or simplified. In a battery (electricity storage device) 100 and a manufacturing method thereof according to the second embodiment, the shapes of the current collecting member 140 and the unwelded current collecting member 140Z are different from those of the current collecting member 40 and the unwelded current collecting member 40Z of the first embodiment.

[0045] Specifically, the unwelded current collecting member 140Z of the second embodiment is a rectangular plate having a overlapping surface 141 and a back surface 142. However, this unwelded current collecting member 140Z has a member gas discharge channel 145 in a second portion 143 that is melted by laser welding. Specifically, this member gas discharge channel 145 is a overlapping surface-side gas discharge groove that is provided in the overlapping surface 141 of the unwelded current collecting member 140Z and is also provided in the second portion 143 and extends in the first member direction DH. In the second embodiment, the second portion 143 of the unwelded current collecting member 140Z is a portion of the unwelded current collecting member 140Z that overlaps with the first portion 33 of the unwelded laminated current collecting part 30Z, that is, a portion on the overlapping surface 141 side and that extends in the first member direction DH. More specifically, the second portion 143 is a portion of the unwelded current collecting member 140Z on the overlapping surface 141 side of both side wall portions 146 that form both side surfaces of the overlapping surface-side gas discharge groove 145.

[0046] In the laser welding step S3 of the second embodiment, the laser beam LB melts the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 143 of the unwelded current collecting member 140Z, and gas generated from these portions 33, 143 is discharged to the outside not only through the gas discharge groove PJv of the light-transmitting pressing jig PJ but also through the overlapping surface-side gas discharge groove 145 of the unwelded current collecting member 140Z, thereby forming the melt-solidified portion 138. Note that the gas discharge groove PJv extends in the first jig direction FH, and the overlapping surface-side gas discharge groove 145 extends in the first-member direction DH, so that gas is discharged to the outside from both sides of the gas discharge groove PJv in the first jig direction FH and from both sides of the overlapping surface-side gas discharge groove 145 in the first-member direction DH.

[0047] This allows gas generated from the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 143 of the unwelded current collecting member 140Z to be appropriately discharged to the outside, thereby particularly effectively suppressing the occurrence of blowholes in the melt-solidified portion 138. In the second embodiment, although a portion of the bottom surface of the overlapping surface-side gas discharge groove 145 remains even after welding (see FIG. 10), the overlapping surface-side gas discharge groove 145 may be eliminated by laser welding. Other portions similar to those in the first embodiment provide the same functions and effects as those in the first embodiment.

[0048] (Embodiment 3) Next, a third embodiment will be described (see FIGS. 11 and 12). Descriptions of parts similar to those of the first or second embodiment will be omitted or simplified. In a battery (electricity storage device) 200 and a manufacturing method thereof according to the third embodiment, the shapes of a current collecting member 240 and an unwelded current collecting member 240Z differ from the shapes of the current collecting members 40, 140 and unwelded current collecting members 40Z, 140Z of the first and second embodiments.

[0049] Specifically, the unwelded current collecting member 240Z of the third embodiment is a rectangular plate having an overlapping surface 241 and a back surface 242. However, this unwelded current collecting member 240Z has a member gas exhaust passage 245 in a second portion 243 that is melted by laser welding. Specifically, this member gas exhaust passage 245 is a gas exhaust through-hole that penetrates between the overlapping surface 241 and the back surface 242 of the unwelded current collecting member 240Z, is provided in the second portion 143, and extends in the first member direction DH. In the third embodiment, the second portion 243 of the unwelded current collecting member 240Z is a portion of the unwelded current collecting member 240Z that overlaps with the first portion 33 of the unwelded laminated current collecting part 30Z, that is, a portion on the overlapping surface 241 side and that extends in the first member direction DH. More specifically, it is a portion of the unwelded current collecting member 240Z on the overlapping surface 241 side of the side wall portion 246 that forms the side surface (inner peripheral surface) of the gas discharge through hole 245.

[0050] In the laser welding process S3 of this embodiment 3, 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 by laser light LB, and the gas generated from these portions 33, 243 is discharged to the outside not only through the gas discharge groove PJv of the translucent pressing jig PJ but also through the gas discharge through hole 245 of the unwelded current collecting member 240Z, and then a molten and solidified portion 238 is formed. This allows gas generated from the first portion 33 of the unwelded laminated current collecting part 30Z and the second portion 243 of the unwelded current collecting member 140Z to be appropriately discharged to the outside, thereby particularly effectively suppressing the generation of blowholes in the melt-solidified portion 238. Other parts similar to those of embodiment 1 or 2 have the same effects as those of embodiment 1 or 2.

[0051] The present invention has been described above in accordance with embodiments 1 to 3, but it goes without saying that the present invention is not limited to embodiments 1 to 3 and can be modified and applied as appropriate within the scope of the gist of the present invention. For example, in the first embodiment and the like, the transparent pressing jig PJ has two ridges PJt and one gas discharge groove PJv formed therebetween, but the numbers of ridges PJt and gas discharge groove PJv are not limited to this. That is, the transparent pressing jig may have three or more ridges and two or more gas discharge grooves formed therebetween.

[0052] Furthermore, in the first embodiment and the like, a battery 1 and the like including a single electrode body 20 have been exemplified, but this is not limiting, and a battery may include multiple electrode bodies. In this case, multiple positive and negative current collecting members may be prepared, and 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 embodiment 1 etc., a laminated electrode body 20 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.

[0053] Furthermore, in the first embodiment and the like, 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. Furthermore, in the first embodiment and the like, the battery 1 and the like are 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 and the like, 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]

[0054] 1,100,200 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 31c (the first part of the pressed part) 32 (Unwelded laminated current collector) pressed area 33 Part 1 38,138,238 Melting and solidification section 40,140,240 Current collecting member 40Z, 140Z, 240Z Unwelded current collecting members 43,143,243 2nd part 145 Gas exhaust groove on overlapping surface (component gas exhaust path) 245 Gas exhaust through hole (component gas exhaust path) 50 terminals SH (Laminated current collector) stacking direction LB laser light PJ Translucent Pressing Jig PJt (Translucent pressing member) convex part PJv (Translucent pressing member) gas discharge groove 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 plurality of ridge portions that protrude toward the unwelded laminated current collecting portion when the translucent pressing jig is placed over the unwelded laminated current collecting portion, and the spaces between these ridge portions form gas discharge grooves; The pressing step includes: pressing a plurality of pressed portions of the unwelded laminated current collecting portion with each of the convex strip portions of the translucent pressing jig to bring the foil current collecting portions into close contact with each other at each of the pressed portions of the unwelded laminated current collecting portion and at pressed portions that are located between these pressed portions and overlap the gas discharge grooves in the stacking direction; The laser welding process includes: The laser light is transmitted through the light-transmitting pressing jig and irradiated onto at least a portion of the pressed portion of the unwelded laminated current collecting portion, thereby melting the first portion including at least a portion of the pressed 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 laser welding process includes: In the unwelded laminated current collecting portion, in addition to the pressed portion, a part of the pressed portion is also set as the first portion to be melted by the laser light. 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 bottom of the gas discharge groove of the light-transmitting pressing jig is flat. A method for manufacturing an electricity storage device.

4. A method for manufacturing the electricity storage device according to claim 1 or 2, comprising: the unwelded current collecting member has a member gas exhaust path at least in the second portion to be melted by the laser light, The laser welding process includes: The gas generated from the first portion and the second portion is discharged to the outside through the gas discharge groove as well as the member gas discharge path. A method for manufacturing an electricity storage device.

Images