Method for manufacturing power storage element, and power storage element

Abstract

This method for manufacturing a power storage element includes: disposing a liquid injection plug to a container so as to close a liquid injection port for an electrolyte formed in the container with the liquid injection plug; and directing laser light onto the container and the liquid injection plug along a site to be welded and welding the container and the liquid injection plug. In the welding, the container and the liquid injection plug are welded by moving the position onto which the laser light is directed along said site while reciprocating in a second direction crossing a first direction that is a direction along said site.

Description

Electricity storage element manufacturing method and electricity storage element

[0001] The present invention relates to a method for manufacturing an energy storage element and to an energy storage element.

[0002] Patent Document 1 discloses a secondary battery that includes a container having a liquid filling port for pouring an electrolyte solution and that contains the electrolyte solution poured through the liquid filling port together with an electrode body, and a sealing lid that is fixed to the container and closes the liquid filling port.

[0003] JP 2012-169254 A

[0004] In the secondary battery disclosed in Patent Document 1, the sealing lid is fixed to the container by laser welding to close the inlet, but if a defect such as a blowhole occurs in the weld between the container and the sealing lid when the sealing lid is laser welded to the container, the welding quality will be reduced. In particular, the sealing lid is small in size and difficult to laser weld to the container, making the defect more likely to occur. If a defect such as a blowhole occurs in the weld between the container and the sealing lid, cracks or holes will form in the weld, reducing the welding quality.

[0005] The present invention was made by the inventor of the present application by focusing on the above-mentioned problem, and aims to provide a manufacturing method for an energy storage element and an energy storage element that can improve the welding quality between the container and the liquid filling tap.

[0006] A method for manufacturing an energy storage element according to one embodiment of the present invention includes: placing a liquid filling plug on a container so that the liquid filling plug blocks an electrolyte filling port formed in the container; and irradiating a laser beam along a portion to be welded between the container and the liquid filling plug, thereby welding the container and the liquid filling plug together.The welding involves moving the irradiation position of the laser beam along the portion to be welded while reciprocating in a second direction that intersects with a first direction that is a direction along the portion to be welded, thereby welding the container and the liquid filling plug together.

[0007] An energy storage element according to one embodiment of the present invention comprises a container having an electrolyte inlet formed therein, and a filler tap that closes the inlet, wherein the container and the filler tap are welded together at a welded portion that extends along a first direction, and the welded portion has a weld mark that moves back and forth in a second direction that intersects the first direction.

[0008] According to the method for manufacturing an electric storage element of the present invention, the quality of the welding between the container and the liquid filling tap can be improved.

[0009] FIG. 1 is a perspective view showing the appearance of an energy storage element according to an embodiment. FIG. 2 is a perspective view showing the internal configuration of a container of an energy storage element according to an embodiment, with a container body separated from the container. FIG. 3 is a cross-sectional perspective view showing the configuration of a liquid inlet and a liquid inlet tap of a lid according to an embodiment. FIG. 4A is a cross-sectional view showing a state in which a liquid inlet tap is disposed on a lid according to an embodiment. FIG. 4B is a cross-sectional view showing a state in which a liquid inlet tap is welded to a lid according to an embodiment. FIG. 5 is a plan view showing a welded portion between the lid and the liquid inlet tap according to an embodiment. FIG. 6 is a plan view showing a step of welding the lid and the liquid inlet tap in a manufacturing method of an energy storage element according to an embodiment. FIG. 7 is a plan view showing in detail a step of welding the lid and the liquid inlet tap in a manufacturing method of an energy storage element according to an embodiment. FIG. 8 is a plan view showing an example of an energy storage device according to an embodiment. FIG. 9 is a cross-sectional view showing a state in which a liquid inlet tap is welded to a lid according to a first modification of the embodiment. FIG. 10 is a plan view showing a step of welding the lid and the liquid inlet tap in a manufacturing method of an energy storage element according to a second modification of the embodiment.

[0010] (1) A method for manufacturing an energy storage element according to one aspect of the present invention includes: arranging a liquid filling plug on a container so that the liquid filling plug blocks an electrolyte filling port formed in the container; and irradiating a laser beam along a portion of the container and the liquid filling plug to be welded, wherein the welding involves moving the irradiation position of the laser beam along the portion to be welded while reciprocating in a second direction that intersects with a first direction that is a direction along the portion to be welded, thereby welding the container and the liquid filling plug.

[0011] According to a manufacturing method of an energy storage element according to one aspect of the present invention, the container and the liquid inlet tap are welded by moving the laser beam irradiation position along the welded portions while reciprocating in a second direction intersecting a first direction along the welded portions of the container and the liquid inlet tap. In this way, when welding the container and the liquid inlet tap, reciprocating the laser beam irradiation position in a direction intersecting the direction along the welded portions agitates the molten pool and allows bubbles in the molten pool to escape. This prevents defects such as blowholes from occurring in the welded portion between the container and the liquid inlet tap, thereby improving the quality of the weld between the container and the liquid inlet tap.

[0012] (2) In the manufacturing method of the energy storage element described in (1) above, the welding may further include moving the irradiation position of the laser light along the portion to be welded while reciprocating in the first direction.

[0013] According to the manufacturing method of the energy storage element described above in (2), the irradiation position of the laser beam is further moved along the portion to be welded while also reciprocating in the first direction, thereby further stirring the molten pool and allowing bubbles in the molten pool to escape, thereby further suppressing defects such as blowholes in the welded portion between the container and the inlet tap.

[0014] (3) In the method for manufacturing an energy storage element described in (1) or (2) above, the welding may involve irradiating the liquid filling plug with the laser light and welding the liquid filling plug to the container by full penetration welding.

[0015] According to the method for manufacturing an electric storage element described above in (3), the liquid filling tap can be more firmly fixed to the container by welding the liquid filling tap to the container by full penetration welding.

[0016] (4) In the method for manufacturing an energy storage element according to any one of (1) to (3) above, the welding may be performed by irradiating the laser light from a fiber laser.

[0017] According to the method for manufacturing an electric storage element described in (4) above, the intensity of the laser light can be increased by irradiating the laser light from a fiber laser, and therefore the liquid filling tap can be more firmly fixed to the container.

[0018] (5) In the method for manufacturing an energy storage element according to any one of (1) to (4) above, the welding may be performed by irradiating the laser beam with a spot diameter of 50 μm or less at the irradiation position.

[0019] According to the manufacturing method of the energy storage element described above in (5), by reducing the spot diameter at the irradiation position to 50 μm or less, welding can be performed to a greater depth, and the liquid filling tap can be more firmly fixed to the container.

[0020] (6) An energy storage element according to one aspect of the present invention comprises a container having an electrolyte inlet formed therein and a filler tap that closes the inlet, and the container and the filler tap are welded together by a weld that extends along a first direction, and the weld has a weld mark that moves back and forth in a second direction that intersects the first direction.

[0021] In an energy storage device according to one aspect of the present invention, a weld extending along a first direction is formed on the container and the liquid filling tap, where the container and the liquid filling tap are welded together, and the weld has a weld mark that moves back and forth in a second direction that intersects the first direction. In this way, the weld between the container and the liquid filling tap has a weld mark that moves back and forth in a direction intersecting the direction of its extension, which indicates that the container and the liquid filling tap were welded together by moving back and forth in the intersecting direction. This indicates that the weld was performed by stirring the molten pool at the weld and allowing air bubbles in the molten pool to escape. This configuration therefore reduces the occurrence of defects such as blowholes in the weld between the container and the liquid filling tap, thereby improving the weld quality between the container and the liquid filling tap.

[0022] Hereinafter, a method for manufacturing an energy storage element and an energy storage element according to an embodiment of the present invention (including its modified examples) will be described with reference to the drawings. The embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In each drawing, dimensions, etc. are not strictly illustrated. In each drawing, the same or similar components are assigned the same reference numerals.

[0023] In the following description and drawings, the X-axis direction is defined as the direction in which the short sides of the container of the energy storage element face each other, the direction in which a pair of terminals (positive and negative electrodes) of the energy storage element are aligned, or the direction in which a pair of current collectors (positive and negative electrodes) are aligned. The Y-axis direction is defined as the direction in which the long sides of the container face each other, the thickness direction of the container, or the thickness direction of the electrode assembly. The Z-axis direction is defined as the direction in which the container body and lid of the container are aligned, the direction in which the electrode assembly and terminals are aligned, the direction in which the terminals protrude from the container, the opening direction of the liquid filling port formed in the container, the direction in which the liquid filling plug is inserted into the liquid filling port, or the up-down direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the up-down direction; however, for convenience of explanation, the Z-axis direction will be described below as the up-down direction.

[0024] In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis direction and the Z-axis direction. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly those. When two directions are parallel (or perpendicular), it does not only mean that the two directions are completely parallel (or perpendicular), but also means that the directions are substantially parallel (or perpendicular), that is, there is a difference of about a few percent. In the following description, when the term "insulation" is used, it means "electrical insulation". The volume resistivity of an insulating material is 1×10 ６Ωm or more is preferable, and 1×10 ７ Ωm or more is more preferable, and 1×10 １０ More preferably, it is Ωm or more.

[0025] (Embodiment) [1 General Description of Energy Storage Device 10] First, a general description of an energy storage device 10 according to the present embodiment will be given using Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing the appearance of an energy storage device 10 according to the present embodiment. Fig. 2 is a perspective view showing the internal configuration of a container 100 of an energy storage device 10 according to the present embodiment, with a container body 110 separated from the container 100.

[0026] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of a moving object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, automatic guided vehicle (AGV), or electric railway vehicle. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the electric railway vehicle include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The energy storage element 10 can also be used as a stationary battery for home or business use.

[0027] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. The energy storage element 10 may be a pouch-type energy storage element. In the present embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped (square) shape that is flattened in the Y-axis direction, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a polygonal prism shape other than a rectangular parallelepiped, an elongated cylinder shape, an elliptical cylinder shape, a cylindrical shape, or the like.

[0028] As shown in FIG. 1 , the energy storage element 10 includes a container 100, a liquid injection plug 200, a pair of terminals 300 (positive and negative electrodes), and a pair of upper gaskets 400 (positive and negative electrodes). As shown in FIG. 2 , the energy storage element 10 includes a pair of lower gaskets 500 (positive and negative electrodes), a pair of current collectors 600 (positive and negative electrodes), and an electrode assembly 700, all of which are housed within the container 100. An electrolyte (non-aqueous electrolyte) is sealed within the container 100, but is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage element 10, and various electrolytes can be selected. In addition to the above components, the energy storage element 10 may also include spacers disposed on the sides or below the electrode assembly 700, an insulating film encasing the electrode assembly 700, and the like.

[0029] The container 100 is a rectangular parallelepiped (square or box-shaped) case comprising a container body 110 with an opening facing the positive direction of the Z axis and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of flat, rectangular short side walls on both sides (short sides) in the X axis direction, a pair of flat, rectangular long side walls on both sides (long sides) in the Y axis direction, and a flat, rectangular bottom wall in the negative Z axis direction. The lid 120 is a member that constitutes the lid of the container 100 and is disposed in the positive Z axis direction of the container body 110. The lid 120 is a flat, rectangular wall extending in the X axis direction.

[0030] After the electrode assembly 700 and other components are housed inside the container body 110, the container body 110 and the lid 120 are joined by welding or the like, thereby sealing the interior of the container 100. The material of the container 100 (container body 110 and lid 120) is not particularly limited and may be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, or a resin. The container 100 may be formed from a laminate film or the like composed of multiple layers including a metal layer and a resin layer. The container body 110 and the lid 120 may be formed from the same material or different materials. As described below, the lid 120 is joined to the liquid filling tap 200 by welding, and therefore at least the portion of the lid 120 joined to the liquid filling tap 200 is formed from a material that can be welded to the liquid filling tap 200.

[0031] The lid 120 is formed with a liquid inlet 130 and a gas exhaust valve 140. The gas exhaust valve 140 is a safety valve that releases pressure when the pressure inside the container 100 increases. The liquid inlet 130 is an opening (electrolyte inlet) formed in the lid 120 for injecting electrolyte into the container 100 during the manufacture of the energy storage device 10. The liquid inlet 130 is a through-hole that penetrates the lid 120 in the Z-axis direction. In the present embodiment, the liquid inlet 130 is a circular through-hole as viewed in the Z-axis direction. However, the shape of the liquid inlet 130 is not limited thereto and may be an elliptical, oval, rectangular, or other polygonal shape as viewed in the Z-axis direction. The liquid inlet 130 is disposed near the negative X-axis direction and at the center of the lid 120 in the Y-axis direction; however, the liquid inlet 130 may be disposed at any position on the lid 120.

[0032] The liquid filling plug 200 is a member that closes the electrolyte filling port 130 formed in the container 100 (lid 120). After the electrolyte is filled into the container 100 through the filling port 130 during the manufacture of the energy storage device 10, the liquid filling plug 200 is joined to the container 100 (lid 120) to close the liquid filling port 130. The material of the liquid filling plug 200 is not particularly limited, and any metal that can be used for the container 100 can be used. In particular, the liquid filling plug 200 is formed from a member that can be welded to the lid 120, such as the same material as the lid 120. Specifically, the material of the liquid filling plug 200 can be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, or a resin can also be used. Although the materials of the lid 120 and the liquid filling plug 200 do not have exactly the same composition, such as when the lid 120 is made of aluminum and the liquid filling plug 200 is made of an aluminum alloy, a combination of joinable materials can also be used. The configuration of the liquid filling tap 200 and the joining configuration between the container 100 (lid 120) and the liquid filling tap 200 will be described in detail later.

[0033] The terminals 300 are electrode terminals (positive and negative terminals) electrically connected to the electrode body 700 via the current collector 600. The terminals 300 are metal members for conducting electricity stored in the electrode body 700 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 700. In this embodiment, two terminals 300 are arranged side by side in the X-axis direction. The terminals 300 are formed of a conductive material such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The terminals 300 are connected (joined) to the current collector 600 by crimping, welding, or the like, and are attached to the lid 120. The terminals 300 are arranged in a state protruding in the positive Z-axis direction from the outer surface (the surface facing the positive Z-axis direction) of the lid 120. In this embodiment, terminal 300 is a welding terminal that is joined to an external conductive member such as a bus bar by welding, but terminal 300 may also be a bolt terminal that has a bolt portion formed with a male thread portion that protrudes in the positive direction of the Z axis and is joined to the conductive member by a bolt connection.

[0034] The upper gasket 400 is a plate-like, rectangular gasket that is disposed between the lid 120 of the container 100 and the terminal 300, and is responsible for insulation and sealing between the lid 120 and the terminal 300. The lower gasket 500 is a plate-like, rectangular gasket that is disposed between the lid 120 and the current collector 600, and is responsible for insulation between the lid 120 and the current collector 600. As the material for the upper gasket 400 and the lower gasket 500, any known material, such as an insulating material such as resin, can be used as appropriate.

[0035] The current collectors 600 are disposed on both sides of the electrode body 700 in the X-axis direction, and are electrically conductive current collecting members (positive electrode current collector and negative electrode current collector) that are connected (joined) to the terminal 300 and the electrode body 700 to electrically connect the terminal 300 and the electrode body 700. The current collectors 600 are fixedly connected (joined) to the lid body 120. In this embodiment, the two current collectors 600 are arranged side by side in the X-axis direction. The material of the current collectors 600 is not particularly limited, but the positive electrode current collector 600 is formed of aluminum or an aluminum alloy, etc., similar to the positive electrode current collector foil of the electrode body 700, and the negative electrode current collector 600 is formed of copper or a copper alloy, etc., similar to the negative electrode current collector foil of the electrode body 700.

[0036] The electrode assembly 700 is an electricity storage element (power generation element) that can store electricity and is formed by stacking positive and negative electrode plates and separators. The electrode assembly 700 is a wound electrode assembly formed by winding the positive and negative electrode plates and separators around a winding axis extending in the X-axis direction. The winding axis is an imaginary axis that serves as the central axis when winding the positive and negative electrode plates, etc., and in this embodiment, it is a straight line that passes through the center of the electrode assembly 700 and is parallel to the X-axis direction. In this embodiment, the electrode assembly 700 has a substantially oval cylindrical shape (an oval shape when viewed from the X-axis direction). The shape of the electrode assembly 700 is not particularly limited and may be a substantially cylindrical shape or a substantially elliptical cylindrical shape, and the length of the electrode assembly 700 in the X-axis direction is also not particularly limited.

[0037] The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode current collector foil, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode current collector foil, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as copper or a copper alloy. The positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer can be any known material as long as they are capable of absorbing and releasing charge-transporting ions. The separator can be a microporous sheet or nonwoven fabric made of resin.

[0038] [2. Description of the Configuration of the Liquid Filling Tap 200 and the Joint Configuration Between the Lid 120 and the Liquid Filling Tap 200] Next, the configuration of the liquid filling tap 200 and the joint configuration between the lid 120 and the liquid filling tap 200 will be described in detail. FIG. 3 is a cross-sectional perspective view showing the configuration of the liquid filling port 130 of the lid 120 and the liquid filling tap 200 according to this embodiment. FIG. 3 is a cross-sectional view showing the configuration of the periphery of the liquid filling port 130 of the lid 120 and the liquid filling tap 200 shown in FIG. 2 when cut along a plane that includes the central axes of the liquid filling port 130 and the liquid filling tap 200 and is parallel to the XZ plane. FIG. 4A is a cross-sectional view showing the liquid filling tap 200 arranged on the lid 120 according to this embodiment. FIG. 4B is a cross-sectional view showing the liquid filling tap 200 welded to the lid 120 according to this embodiment. Fig. 4A shows a state in which the liquid filling tap 200 is attached to the lid 120 shown in Fig. 3, and Fig. 4B shows a state in which the liquid filling tap 200 is welded to the lid 120 of Fig. 4A. Fig. 5 is a plan view showing a welded portion 800 between the lid 120 and the liquid filling tap 200 according to this embodiment. Fig. 5 is a top view of the configuration shown in Fig. 4B as seen from above (positive direction of the Z axis).

[0039] As shown in Figures 3, 4A, and 4B, the liquid filling tap 200 includes a liquid filling tap main body 210 and a liquid filling tap shaft 220. The liquid filling tap main body 210 is disposed in the positive direction of the Z axis from the liquid filling port 130 and is the main body of the liquid filling tap 200 that covers the liquid filling port 130. The liquid filling tap main body 210 is a portion (flange) of the liquid filling tap 200 that is located in the positive direction of the Z axis and has a circular (disk-like) shape when viewed from the Z axis direction, and is welded to the lid 120 in a state where it covers the entire liquid filling port 130. The liquid filling tap main body 210 is provided with a liquid filling tap recess 211 and a liquid filling tap outer periphery 212.

[0040] The liquid filling tap recess 211 is located at the center of the outer surface (the surface facing the positive Z-axis direction) of the liquid filling tap main body 210, and is a generally truncated cone-shaped recess recessed toward the negative Z-axis direction. The liquid filling tap recess 211 is used as a mark when joining the liquid filling tap 200 to the lid 120. The liquid filling tap recess 211 makes it possible to determine the position of the liquid filling tap 200, so the liquid filling tap 200 can be positioned accurately on the lid 120 and joined to the lid 120. The liquid filling tap outer periphery 212 is a peripheral portion that includes the outer edge of the liquid filling tap main body 210 as viewed in the Z-axis direction, and is a ring-shaped portion as viewed in the Z-axis direction. The liquid filling tap outer periphery 212 is welded to the lid 120 while in contact with the lid 120.

[0041] The liquid filling tap shank 220 protrudes from the liquid filling tap main body 210 of the liquid filling tap 200 and is a protrusion that is inserted into the liquid filling port 130 of the lid 120. When viewed from the Z-axis direction, the liquid filling tap shank 220 is located at the center of the liquid filling tap main body 210 and is a substantially cylindrical portion that extends from this center position in the negative Z-axis direction. The liquid filling tap shank 220 includes a pillar portion 221 and a reduced diameter portion 222. The pillar portion 221 is a cylindrical portion of the liquid filling tap shank 220 that is located in the positive Z-axis direction. When viewed from the Z-axis direction, the pillar portion 221 has an outer circumferential shape that is substantially the same as the inner circumferential shape of the liquid filling port 130, and is press-fitted (engaged) into the liquid filling port 130. The reduced diameter portion 222 is a substantially truncated cone-shaped portion whose diameter gradually decreases from the end of the pillar portion 221 in the negative Z-axis direction toward the negative Z-axis direction. In this way, the liquid filling tap shaft 220 has a tapered tip portion so that it can be easily inserted into the liquid filling port 130 of the lid 120 .

[0042] As shown in FIGS. 4B and 5 , a weld 800 is formed on the container 100 and the liquid filling tap 200, where the container 100 and the liquid filling tap 200 are welded together. A weld 800 is formed on the lid 120 and the liquid filling tap outer periphery 212, where the lid 120 and the liquid filling tap outer periphery 212 are welded together. The weld 800 is a laser weld formed by irradiating the lid 120 and the liquid filling tap outer periphery 212 with laser light L. The weld 800 is a fused portion formed by laser welding a portion on the outer surface of the lid 120 and the liquid filling tap outer periphery 212 together. The weld 800 is a full-fill weld formed by passing through the liquid filling tap outer periphery 212 and welding the liquid filling tap outer periphery 212 and the lid 120 together. The weld 800 is an annular weld mark extending along the outer edge of the liquid filling tap outer periphery 212 when viewed in the Z-axis direction. As shown in FIGS. 4B and 5 , when viewed from the Z-axis direction, the weld 800 is formed across both the liquid filling tap outer periphery 212 and the lid 120. The outermost range of the weld 800, when viewed from the Z-axis direction, extends beyond the liquid filling tap outer periphery 212 and outside the liquid filling tap 200, reaching into the range of the lid 120. In this embodiment, the weld 800 is a weld mark that moves back and forth in a direction intersecting the outer edge of the liquid filling tap outer periphery 212. More specifically, the weld 800 is a weld mark that moves back and forth in the direction of extension of the outer edge of the liquid filling tap outer periphery 212 and also in a direction intersecting the outer edge. A specific technique (a method of manufacturing the energy storage element 10) for welding the lid 120 and the liquid filling tap 200 to form the weld 800 will be described in detail below.

[0043] [3 Description of Manufacturing Method of Energy Storage Device 10] The step of welding the lid body 120 and the liquid filling plug 200 together in the manufacturing method of the energy storage device 10 will be described in detail with reference to Figs. 6 and 7 as well. Fig. 6 is a plan view showing the step of welding the lid body 120 and the liquid filling plug 200 together in the manufacturing method of the energy storage device 10 according to the present embodiment. Fig. 6 is a view corresponding to Fig. 5 and shows the trajectory of the irradiation position 820 of the laser beam L when laser welding the lid body 120 and the liquid filling plug 200 together. Fig. 7 is a plan view showing in detail the step of welding the lid body 120 and the liquid filling plug 200 together in the manufacturing method of the energy storage device 10 according to the present embodiment. Fig. 7 is a view explaining the movement of the irradiation position 820 of the laser beam L shown in Fig. 6.

[0044] First, as shown in FIG. 4A , the liquid filling tap 200 is placed on the container 100 (lid 120) so that the liquid filling tap 200 closes the liquid filling port 130 for electrolyte formed in the container 100 (lid 120). This process is referred to as the "liquid filling tap placing process" or "placing." Specifically, the liquid filling tap shaft 220 of the liquid filling tap 200 is inserted (press-fit) into the liquid filling port 130 of the lid 120 and engaged with the liquid filling port 130. This brings the liquid filling tap shaft 220 (pillar portion 221) into contact with the inside (inner surface) of the liquid filling port 130. The liquid filling tap 200 is placed on the lid 120 with the liquid filling tap outer periphery 212 of the liquid filling tap main body 210 overlapping and in contact with the lid 120. The liquid filling tap outer periphery 212 is located in the negative Z-axis direction relative to the central region of the liquid filling tap main body 210, which is located in the positive Z-axis direction of the column 221. Specifically, the liquid filling tap 200 has the liquid filling tap outer periphery 212 at a position inclined toward the negative Z-axis direction from the central region of the liquid filling tap main body 210. As a result, when the liquid filling tap 200 is placed on the lid 120, the liquid filling tap outer periphery 212 comes into contact with the lid 120.

[0045] Next, as shown in FIG. 4B , a laser beam L is irradiated along a welding target portion 810 between the container 100 (lid 120) and the liquid filling tap 200, thereby welding the container 100 (lid 120) and the liquid filling tap 200. This process is referred to as a "liquid filling tap welding process" or "welding." As shown in FIG. 6 , a laser beam L is irradiated along a welding target portion 810 between the lid 120 and the liquid filling tap 200, thereby welding the lid 120 and the liquid filling tap 200. The welding target portion 810 is a portion where a weld (molten portion) is desired to be formed in order to weld the lid 120 and the liquid filling tap 200. In this embodiment, the welding target portion 810 is an annular portion that follows the outer edge of the liquid filling tap outer periphery 212 as viewed in the Z-axis direction. As shown by the dashed line in FIG. 6 , the welding target portion 810 is formed across both the liquid filling tap outer periphery 212 and the lid 120 as viewed in the Z-axis direction. The outermost range of the portion to be welded 810, as viewed from the Z-axis direction, extends beyond the liquid filling tap outer periphery 212 and outside the liquid filling tap 200, reaching into the range of the lid 120. As a result, the liquid filling tap outer periphery 212, which is overlapped on the lid 120 in the Z-axis direction, is welded to the lid 120 along the entire circumference. Specifically, laser light L is irradiated from the positive direction of the Z-axis toward the portion to be welded 810 between the lid 120 and the liquid filling tap outer periphery 212, and as shown in FIG. 5 , a ring-shaped weld 800 is formed as viewed from the Z-axis direction by laser welding the lid 120 and the liquid filling tap outer periphery 212. The above-mentioned "welding" (liquid filling tap welding process) will be described in further detail below.

[0046] In the "welding" (liquid filling tap welding step), the irradiation position 820 of the laser beam L is moved along the welding target portion 810 while reciprocating in a second direction intersecting a first direction that is a direction along the welding target portion 810, thereby welding the container 100 and the liquid filling tap 200. In the "welding" (liquid filling tap welding step), the irradiation position 820 of the laser beam L is further moved along the welding target portion 810 while reciprocating in the first direction. Because the welding target portion 810 is an annular portion that follows the outer edge of the liquid filling tap outer periphery 212, the direction along the welding target portion 810 (first direction) is the direction along the outer edge of the liquid filling tap outer periphery 212. In the present embodiment, as shown in FIG. 6 , the irradiation position 820 of the laser beam L is moved in the direction along the outer edge of the liquid filling tap outer periphery 212 (first direction) while rotating so as to describe an annular shape such as a circle. As a result, the irradiation position 820 of the laser light L reciprocates in a direction along the outer edge (first direction) and a direction intersecting the direction along the outer edge (second direction).

[0047] Specifically, as shown in FIG. 7A , the irradiation position 821 of the laser beam L is moved in a direction along the outer edge of the liquid filling tap outer periphery 212 while rotating it to describe an annular shape such as a circle, thereby welding the lid 120 and the liquid filling tap outer periphery 212. The irradiation position 821 is moved in a direction A1 that includes a direction along the outer edge of the liquid filling tap outer periphery 212, a direction B1 that intersects with direction A1, a direction C1 that includes a direction opposite to direction A1, and a direction D1 that includes a direction opposite to direction B1. The directions A1 and C1 are directions that extend along the outer edge of the liquid filling tap outer periphery 212 (directions that extend along the portion 810 to be welded) and are opposite to each other. The direction A1 includes one side of the first direction, and the direction C1 includes the other side of the first direction. The directions B1 and D1 are directions that intersect with the first direction and are opposite to each other. The direction B1 includes one side of the second direction, and the direction D1 includes the other side of the second direction. In this way, the irradiation position 821 of the laser light L moves in a direction (first direction) along the outer edge of the liquid filling tap outer periphery 212 while rotating so as to describe an annular shape such as a circle, thereby reciprocating in the first direction and in the second direction.

[0048] As shown in Figure 7(b) , following irradiation position 821, irradiation position 822 is moved in a direction along the outer edge of the liquid filling tap outer periphery 212 while rotating so as to describe an annular shape such as a circle, thereby welding the lid 120 and the liquid filling tap outer periphery 212. Irradiation position 822 is moved in direction A2 that includes a direction along the outer edge of the liquid filling tap outer periphery 212, in direction B2 that intersects with direction A2, in direction C2 that includes a direction opposite to direction A2, and in direction D2 that includes a direction opposite to direction B2. As shown in Figure 7(c) , following irradiation position 822, irradiation position 823 is moved in a direction along the outer edge of the liquid filling tap outer periphery 212 while rotating so as to describe an annular shape such as a circle, thereby welding the lid 120 and the liquid filling tap outer periphery 212. The irradiation position 823 is moved in direction A3 that includes a direction along the outer edge of the liquid filling tap outer periphery 212, in direction B3 that intersects with direction A3, in direction C3 that includes a direction opposite to direction A3, and in direction D3 that includes a direction opposite to direction B3. In this way, the irradiation positions 822 and 823 of the laser light L move in a direction along the outer edge of the liquid filling tap outer periphery 212 (first direction) while rotating so as to describe an annular shape such as a circle, thereby reciprocating in the first direction and in the second direction.

[0049] By repeating the above, a weld 800 is formed on the container 100 (lid 120) and the liquid filling tap 200, where the container 100 (lid 120) and the liquid filling tap 200 are welded together, and the weld 800 extends along the first direction. The weld 800 has a weld mark that moves back and forth in a second direction that intersects with the first direction. Specifically, as the irradiation position 820 of the laser light L moves back and forth in the first direction and then in the second direction, the weld 800 has a weld mark that moves back and forth in the first direction and then in the second direction. The weld 800 is formed on the lid 120 and the liquid filling tap 200 by wobbling welding in a shape that follows the irradiation position 820 of the laser light L. The weld 800 has a weld mark that follows the irradiation position 820, formed by wobbling welding.

[0050] The irradiation positions 820 of the laser light L move in a direction (first direction) along the welding target portion 810 while rotating in a circular shape such as a circle. The density of the irradiation positions 820 can be adjusted by changing the speed of movement in the first direction. By decreasing (slowing) the speed of movement in the first direction, irradiation positions such as 821, 822, and 823 are arranged more densely, thereby more firmly welding the lid body 120 and the liquid filling tap outer periphery 212. For ease of explanation, FIG. 7 illustrates irradiation positions such as 821, 822, and 823 as being less densely spaced than the irradiation positions 820 shown in FIG. 6 , but the irradiation positions may be more densely spaced. Even when the irradiation positions are not arranged more densely, it is preferable to arrange the irradiation positions relatively close to each other, such as by making the weld 800 formed at irradiation position 821 and the weld 800 formed at irradiation position 822 overlap in the first direction, in order to more reliably weld the lid body 120 and the liquid filling tap outer periphery 212.

[0051] In the above-described "welding" (liquid filling plug welding step), a laser beam L is irradiated onto the liquid filling plug 200, and the liquid filling plug 200 is welded to the container 100 by full-thickness welding. In this embodiment, the irradiation position 820 of the laser beam L is reciprocated in the second direction so as to straddle the outer edge of the liquid filling plug outer periphery 212. When the irradiation position 820 is located on the liquid filling plug outer periphery 212, the laser beam L is irradiated onto the liquid filling plug outer periphery 212, and the liquid filling plug outer periphery 212 is welded to the lid 120 by full-thickness welding. A continuous weld 800 is formed from the end of the liquid filling plug outer periphery 212 in the positive Z-axis direction to a portion of the lid 120 in the positive Z-axis direction. As shown in FIG. 7 , in this embodiment, the rotation center P of the laser beam L is positioned inside the liquid filling plug 200 relative to the outer edge of the liquid filling plug outer periphery 212, thereby increasing the area of ​​the liquid filling plug 200 that is full-thickness welded. The rotation center P of the laser light L may be located at the same position as the outer edge of the liquid filling tap outer periphery 212 , or may be located outside the liquid filling tap 200 with respect to the outer edge of the liquid filling tap outer periphery 212 .

[0052] In the above-described "welding" (liquid inlet plug welding step), laser light L is emitted from a fiber laser. A fiber laser is a laser in which light of a specific wavelength is amplified within an optical fiber. A single-mode or multi-mode fiber laser can be used as the laser light L. A single-mode fiber laser is a fiber laser output from a single optical fiber, which has a small spot diameter and a deep welding depth. A multi-mode fiber laser is a fiber laser output from multiple optical fibers, which has a large spot diameter and a shallow welding depth. In this embodiment, because the small-sized liquid inlet plug 200 is welded to the lid 120 by full-penetration welding, it is preferable to use a single-mode fiber laser as the laser light L, which has a small spot diameter and a deep welding depth.

[0053] Specifically, in the "welding" (liquid filling plug welding step), laser light L is irradiated with a spot diameter of 50 μm or less at the irradiation position 820. The spot diameter of the laser light L at the irradiation position 820 is preferably 45 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less. The smaller the spot diameter of the laser light L, the deeper the welding depth can be achieved with lower output. It is preferable that the spot diameter of the laser light L is not made too small from technical and cost perspectives, etc.

[0054] A galvanometer scanner can be used to irradiate the laser light L (fiber laser). The galvanometer scanner is a device that can freely move the irradiation position 820 of the laser light L in the XY plane by independently driving two galvanometer mirrors. This makes it possible to easily control the irradiation position 820 of the laser light L. It is also possible to use a device in which a laser head that irradiates the laser light is attached to the arm of a robot and the laser head is moved in the XY plane.

[0055] The output of the laser light L (fiber laser) at the welded portion 800 may be constant or may vary. In the present embodiment, the output of the laser light L is constant. However, since heat accumulates in the portion to be welded 810 during the process of forming the welded portion 800, the output of the laser light L at the end point of the welded portion 800 can be reduced. Therefore, the output of the laser light L at the end point of the welded portion 800 may be reduced compared to the output of the laser light L at the start point of the welded portion 800. The output of the laser light L may be gradually reduced from the start point to the end point of the welded portion 800. Alternatively, the output of the laser light L at the portion of the liquid filling tap 200 where the full-thickness welding is performed may be increased compared to the output of the laser light L at the portion of the liquid filling tap 200 where the full-thickness welding is not performed. The output of the laser light L where the irradiation position 820 is inside the liquid filling tap 200 may be increased compared to the output of the laser light L where the irradiation position 820 is outside the liquid filling tap 200. This facilitates full-thickness welding. In this embodiment, the end point of welding of welded portion 800 is made to overlap (connect) with the start point of welding of welded portion 800, but the end point of welding may also be positioned at a position offset from the start point of welding without overlapping.

[0056] In the above-described "welding" (liquid filling tap welding step), the liquid filling tap outer periphery 212 of the liquid filling tap 200 may be welded multiple times. A single welding operation of welding the annular weld target portion 810 shown in FIG. 6 once is considered one revolution, and this welding operation may be repeated multiple times to weld the weld target portion 810 multiple times. To improve the welding quality between the container 100 and the liquid filling tap 200, it is preferable to weld the liquid filling tap outer periphery 212 of the liquid filling tap 200 many times. However, if the number of revolutions is too large, the time required for welding (takt time) will increase too much. For this reason, the number of revolutions is preferably two or more and four or less, and more preferably three.

[0057] When welding the outer periphery 212 of the liquid filling tap 200 in multiple turns, the turning radius (the distance between the center position of the liquid filling tap 200 and the welded portion 800) may be the same or different. In this embodiment, the same turning radius and the same position are welded in multiple turns. The same turning radius and different positions may be welded in multiple turns. The turning radius may be gradually increased or decreased in multiple turns. In this embodiment, the width of the portion 810 to be welded is the same in multiple turns, but the width of the portion 810 to be welded may be different.

[0058] In this embodiment, the laser output of the laser beam from the second round onward in multiple turns is the same as that of the laser beam from the first round, but may be changed from that of the first round. When changing the turning radius in multiple turns, the laser output may be changed from the viewpoint of smoothing the surface of the welded portion 800. The laser output may be gradually decreased or increased in multiple turns. In this embodiment, welding is performed continuously without interruption between the first and second turns in multiple turns, but may be interrupted and welded intermittently. The same applies to the third round and beyond. In this embodiment, wobbling welding is performed in the second round and beyond in multiple turns, similar to that in the first round. However, laser welding (e.g., pulse laser) different from wobbling welding may also be performed. However, as described below, wobbling welding is preferably performed in the second round and beyond from the viewpoint of scraping out electrolyte components remaining in the welded portion 800. From the viewpoint of takt time, it is preferable to increase the welding speed (wobbling speed) as the number of turns increases. In this embodiment, welding is performed at the same speed for multiple revolutions, but the welding speed may be gradually increased as the revolutions progress.

[0059] [4 Description of Effects] As described above, according to the manufacturing method for the energy storage element 10 according to the embodiment of the present invention, the container 100 and the liquid filling tap 200 are welded by moving the irradiation position 820 of the laser beam L along the welding target portion 810 while reciprocating in a second direction intersecting a first direction along the welding target portion 810 between the container 100 and the liquid filling tap 200. In this way, when welding the container 100 and the liquid filling tap 200, reciprocating the irradiation position 820 of the laser beam L in a direction intersecting the direction along the welding target portion 810 agitates the molten pool and allows air bubbles in the molten pool to escape. This makes it possible to suppress the occurrence of defects such as blowholes in the welded joint 800 between the container 100 and the liquid filling tap 200, thereby improving the welding quality between the container 100 and the liquid filling tap 200. If blowholes can be prevented from occurring in the welded portion 800, defects such as cracks or holes in the welded portion 800 can be prevented, thereby improving the welding quality between the container 100 and the liquid filling tap 200.

[0060] In the manufacturing method of the energy storage element 10, the irradiation position 820 of the laser beam L is further moved back and forth in the first direction while being moved along the portion to be welded 810, thereby further stirring the molten pool and allowing bubbles in the molten pool to escape to the outside. This further prevents defects such as blowholes from occurring in the welded portion 800 between the container 100 and the liquid filling tap 200.

[0061] In the method for manufacturing the energy storage device 10, the liquid filling tap 200 can be more firmly fixed to the container 100 by welding the liquid filling tap 200 to the container 100 by full penetration welding.

[0062] In the method for manufacturing the energy storage element 10, the intensity of the laser light L is increased by irradiating the laser light L from a fiber laser, and therefore the liquid filling plug 200 can be more firmly fixed to the container 100. If the intensity of the laser light L can be increased, the liquid filling plug 200 can be easily welded to the container 100 by full penetration welding. Because the fiber laser has a wide range of focal depth, there is no need to adjust the depth, making the welding operation easier.

[0063] In the method for manufacturing the energy storage device 10, by reducing the spot diameter at the irradiation position 820 to 50 μm or less, welding can be performed to a greater depth, and the liquid filling tap 200 can be fixed to the container 100 more firmly.

[0064] In the manufacturing method of the energy storage device 10, the liquid filling plug outer periphery 212 of the liquid filling plug 200 may be welded multiple times. In this case, the first turn removes electrolyte components from the portion 810 to be welded, and the second and subsequent turns can smooth the surface of the welded portion 800 and scrape out any electrolyte components remaining in the welded portion 800. If electrolyte components remain in the welded portion 800 after the first turn, blowholes are likely to occur in the welded portion 800. Therefore, the second and subsequent turns scrape out the electrolyte components remaining in the welded portion 800 and fill any blowholes that occur after the first turn. This leaves only air bubbles deep in the welded portion 800, thereby preventing blowholes from occurring in the welded portion 800. Welding the liquid filling plug outer periphery 212 of the liquid filling plug 200 three or more times more reliably prevents blowholes from occurring in the welded portion 800. Considering the takt time, the number of revolutions for welding the outer periphery 212 of the liquid filling tap 200 is preferably two or more and four or less, and more preferably three revolutions.

[0065] Generally, when welding is performed by laser welding using a pulsed laser, the welding speed is slower than when welding is performed by wobbling welding as in the present embodiment. Wobbling welding continuously irradiates laser light by CW (Continuous Wave) oscillation, whereas laser welding using a pulsed laser irradiates laser light intermittently by pulse oscillation, resulting in a slower welding speed. Therefore, from the standpoint of takt time, laser welding avoids welding the outer periphery 212 of the liquid inlet tap 200 multiple times, and the idea of ​​welding multiple times is unthinkable. In the present embodiment, multiple-time welding is possible precisely because it is wobbling welding using a CW laser.

[0066] Laser welding is more likely to generate spatter than wobbling welding. Therefore, when the outer periphery 212 of the liquid filling tap 200 is welded multiple times, the amount of spatter generated from the welding target portion 810 increases, causing the thickness of the welded portion 800 to become thinner. This reduces the strength of the welded portion 800 and the quality of the weld between the container 100 and the liquid filling tap 200. From this perspective, laser welding avoids welding the outer periphery 212 of the liquid filling tap 200 multiple times, and the idea of ​​welding multiple times is unthinkable. In this embodiment, wobbling welding enables multiple welding times while preventing the thickness of the welded portion 800 from becoming thinner, thereby improving the quality of the weld between the container 100 and the liquid filling tap 200.

[0067] According to the energy storage device 10 of the embodiment of the present invention, the container 100 and the liquid filling tap 200 are welded together, forming a weld 800 extending along a first direction. The weld 800 includes a weld mark that moves back and forth in a second direction intersecting the first direction. Because the weld 800 between the container 100 and the liquid filling tap 200 includes a weld mark that moves back and forth in a direction intersecting the direction of its extension, it is clear that the container 100 and the liquid filling tap 200 were welded together while moving back and forth in the intersecting direction. This indicates that the weld was performed by stirring the molten pool at the weld 800 and allowing air bubbles within the molten pool to escape. This configuration reduces the occurrence of defects such as blowholes at the weld 800 between the container 100 and the liquid filling tap 200, thereby improving the welding quality between the container 100 and the liquid filling tap 200.

[0068] The energy storage element 10 in the present embodiment may be used in an energy storage device. In this case, the technology of the present invention may be applied to at least one energy storage element 10 included in the energy storage device. FIG. 8 is a plan view showing an example of an energy storage device 12 according to the present embodiment. As shown in FIG. 8, a plurality of energy storage units 11 are arranged inside the energy storage device 12. The energy storage unit 11 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 12 may include a bus bar (not shown) that electrically connects the plurality of energy storage elements 10, a bus bar (not shown) that electrically connects the plurality of energy storage units 11, and the like. The energy storage unit 11 or the energy storage device 12 may include a status monitoring device (not shown) that monitors the status of one or more energy storage elements 10. The energy storage device 12 may include only one energy storage unit 11. The energy storage unit 11 may also be referred to as an energy storage device.

[0069] [5. Description of Modifications] The manufacturing method of the energy storage device 10 according to the embodiment of the present invention and the energy storage device 10 have been described above, but the present invention is not limited to the above embodiment. The embodiment disclosed herein is an example in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0070] (Variation 1) In the above embodiment, the irradiation position 820 of the laser beam L is moved back and forth in the second direction so as to straddle the outer edge of the liquid filling tap outer periphery 212 of the liquid filling tap 200. However, the irradiation position 820 may be moved back and forth in the second direction inside the liquid filling tap 200 further inside than the outer edge of the liquid filling tap outer periphery 212. Figure 9 is a cross-sectional view showing the state in which the liquid filling tap 200 is welded to the lid 120 according to Variation 1 of this embodiment. Figure 9 is a view corresponding to Figure 4B.

[0071] As shown in FIG. 9 , in this modification, a weld 800 is formed inside the outer edge of the liquid filling tap 200's outer periphery 212. A portion to be welded 810 is located inside the liquid filling tap 200's outer periphery 212. The lid 120 and the liquid filling tap 200 are welded by moving an irradiation position 820 of the laser beam L back and forth in the second direction inside the liquid filling tap 200's outer periphery 212 while moving the irradiation position 820 along the portion to be welded 810. This forms the weld 800 inside the liquid filling tap 200's outer periphery 212. The entire weld 800 is a fully welded portion.

[0072] In this modified example, a weld 800 is formed inside the outer edge of the liquid filling tap outer periphery 212 of the liquid filling tap 200, but the range of the weld 800 is the range where the liquid filling tap main body 210 and the lid 120 are in contact with each other without any gaps before welding. Specifically, as shown in FIG. 9 , the liquid filling tap main body 210 has a gap between it and the lid 120 in a range close to the liquid filling tap shaft 220. Because the tip of the outer edge of the liquid filling tap outer periphery 212 has an arc-shaped cross section, there is a region at the very tip of the outer edge of the liquid filling tap outer periphery 212 that is not in contact with the lid 120. In this modified example, the weld 800 is formed in the range where the liquid filling tap main body 210 and the lid 120 are in contact with each other without any gaps before welding, avoiding the range where there is a gap between the liquid filling tap main body 210 and the lid 120 and they are not in contact.

[0073] The remaining configuration of this modified example is the same as that of the above-described embodiment, and therefore detailed description will be omitted. The energy storage device according to this modified example can achieve the same effects as those of the above-described embodiment. In particular, in this modified example, the entire welded portion 800 is a full-penetration welded portion, which allows the liquid filling tap 200 to be more firmly fixed to the lid 120. In this modified example, the welded portion 800 is provided in an area where the liquid filling tap main body 210 and the lid 120 are in contact with each other without any gaps even before welding, thereby improving the welding quality between the lid 120 and the liquid filling tap 200.

[0074] (Variation 2) In the above embodiment, the irradiation position 820 of the laser light L moves in a direction (first direction) along the outer edge of the liquid filling tap outer periphery 212 while rotating so as to describe an annular shape such as a circle, but this is not limited to this. Fig. 10 is a plan view showing a step of welding the lid 120 and the liquid filling tap 200 together in a manufacturing method for the energy storage device 10 according to Variation 2 of the present embodiment. Fig. 10 is a view corresponding to a portion in the positive direction of the X-axis in the configuration shown in Fig. 6.

[0075] As shown in FIG. 10 , in this modification, the irradiation position 830 of the laser beam L moves in a direction (first direction) along the outer edge of the liquid filling tap outer periphery 212 while reciprocating in a second direction intersecting the first direction. Specifically, the irradiation position 830 of the laser beam L moves in a curved manner in the first direction while reciprocating linearly in the second direction. As a result, the irradiation position 830 reciprocates in a zigzag manner in the second direction along the direction (first direction) along the outer edge of the liquid filling tap outer periphery 212. In the above-described "welding" (liquid filling tap welding step), the irradiation position 830 of the laser beam L is moved along the areas to be welded while reciprocating in a second direction intersecting the first direction, which is the direction along the areas to be welded, thereby welding the container 100 (lid 120) and the liquid filling tap 200. As a result, a weld extending along the first direction is formed in the container 100 (lid 120) and the liquid filling tap 200, and the weld has a weld mark reciprocating in the second direction.

[0076] The other configurations of this modified example are the same as those of the above-described embodiment, and therefore detailed description thereof will be omitted. The energy storage element according to this modified example can achieve the same effects as those of the above-described embodiment. In particular, in this modified example, the irradiation position 830 of the laser light L is not moved back and forth in the first direction, making it easy to control the irradiation position 830. In this modified example, the irradiation position 830 of the laser light L may be moved back and forth in a curved line in the second direction.

[0077] (Other Modifications) In the above embodiment, the liquid inlet 130 is formed in the lid 120 of the container 100, and the liquid inlet tap 200 is welded to the lid 120, but the liquid inlet 130 may be formed in the container body 110 of the container 100, and the liquid inlet tap 200 may be welded to the container body 110.

[0078] In the above embodiment, the liquid filling tap 200 is provided with a liquid filling tap shaft 220 that is inserted into the liquid filling port 130. However, the liquid filling tap 200 may not be provided with the liquid filling tap shaft 220, and the liquid filling tap main body 210 may be joined to the container 100 to close the liquid filling port 130. The liquid filling tap main body 210 of the liquid filling tap 200 may not be provided with the liquid filling tap recess 211.

[0079] In the above embodiment, the above configuration is applied around the entire circumference of the liquid filling tap outer periphery 212 of the liquid filling tap 200, but the above configuration does not have to be applied to a part of the liquid filling tap outer periphery 212.

[0080] In the above embodiment, the liquid filling tap 200 is welded to the container 100 by full-thickness welding, but the liquid filling tap 200 may also be welded to the container 100 without full-thickness welding.

[0081] In the above embodiment, the liquid filling tap 200 is welded to the container 100 by irradiating it with laser light L from a fiber laser, but the liquid filling tap 200 may also be welded to the container 100 by irradiating it with laser light L other than a fiber laser. The spot diameter at the irradiation position 820 of the laser light L may be greater than 50 μm.

[0082] In the above embodiment, the liquid filling tap outer periphery 212 of the liquid filling tap 200 is an annular portion, and the portion to be welded 810 is an annular portion that follows the liquid filling tap outer periphery 212. However, this is not limited to this. The liquid filling tap outer periphery 212 may be an elliptical, oval, rectangular, or other polygonal ring-shaped portion, and the portion to be welded 810 may be an elliptical, oval, rectangular, or other polygonal ring-shaped portion that follows the liquid filling tap outer periphery 212. The portion to be welded 810 may have an annular, elliptical, oval, rectangular, or other polygonal ring-shaped portion that does not follow the liquid filling tap outer periphery 212. In this case, the container 100 and the liquid filling tap 200 can be welded by moving the irradiation position 820 of the laser light L along the portion to be welded 810.

[0083] In the above embodiment, the irradiation position 820 of the laser beam L is moved along the parts to be welded 810 while rotating so as to describe an annular shape such as a circle, but this is not limited to this. The irradiation position 820 of the laser beam L may be moved along the parts to be welded 810 while rotating so as to describe an annular shape surrounded by curves other than a circle, such as an ellipse or an oval, or an annular shape surrounded by straight lines, such as a rectangle or other polygon. The irradiation position 820 of the laser beam L may be moved along the parts to be welded 810 while rotating so as to describe an annular shape.

[0084] In the above embodiment, the electrode assembly 700 is a wound electrode assembly whose winding axis is parallel to the lid body, but it may also be a wound electrode assembly whose winding axis is perpendicular to the lid body. The shape of the electrode assembly 700 is not limited to a wound type, and may be a stack type formed by stacking multiple flat electrode plates, or a shape in which the electrode plates and / or separators are folded in an accordion-like shape (e.g., a shape in which a separator is accordion-shaped and sandwiches a rectangular electrode plate, a shape in which the electrode plate and separator are stacked and then formed into an accordion-like shape, etc.). The electrode assembly 700 may include a tab connected (joined) to the current collector 600.

[0085] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0086] The present invention can be applied to a method for manufacturing an electric storage device such as a lithium ion secondary battery.

[0087] REFERENCE SIGNS LIST 10 Energy storage element 11 Energy storage unit 12 Energy storage device 100 Container 110 Container body 120 Lid 130 Filling port 140 Gas release valve 200 Filling tap 210 Filling tap body 211 Filling tap recess 212 Outer periphery of filling tap 220 Filling tap shaft 221 Pillar 222 Reduced diameter portion 300 Terminal 400 Upper gasket 500 Lower gasket 600 Current collector 700 Electrode body 800 Welded portion 810 Part to be welded 820, 821, 822, 823, 830 Irradiation position

Claims

1. A method for manufacturing an energy storage element, comprising: placing a liquid filling plug on a container so that the liquid filling plug closes an electrolyte filling port formed in the container; and irradiating a laser beam along a portion of the container and the liquid filling plug to be welded, wherein the welding involves moving the irradiation position of the laser beam along the portion to be welded while reciprocating in a first direction that is a direction along the portion to be welded, in a second direction that intersects with the first direction.

2. The method for manufacturing a storage element according to claim 1, wherein the welding further comprises moving the irradiation position of the laser light along the portion to be welded while reciprocating in the first direction.

3. The method for manufacturing an energy storage element according to claim 1 or 2, wherein the welding comprises irradiating the liquid filling plug with the laser light and welding the liquid filling plug to the container by full penetration welding.

4. The method for manufacturing an energy storage element according to claim 1 or 2, wherein the welding is performed by irradiating the laser light from a fiber laser.

5. The method for manufacturing an energy storage element according to claim 1 or 2, wherein the welding is performed by irradiating the laser beam with a spot diameter of 50 μm or less at the irradiation position.

6. An energy storage element comprising: a container having an electrolyte inlet formed therein; and a filling tap that closes the inlet, wherein the container and the filling tap are welded together at a welded portion that extends along a first direction, and the welded portion has a weld mark that moves back and forth in a second direction that intersects with the first direction.

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