JP2023150049A - Energy storage element - Google Patents

Abstract

To provide a power storage element capable of improving a quality of bonding between a lamination part and a collector of an electrode.SOLUTION: A power storage element 10 comprises: an electrode body 300 having a lamination part 320; and a collector 400 connected to the lamination part 320. The lamination part 320 is nipped by a first part (an electrode connection part 420) as one part of the collector 400 in a first direction and a second part (a patch 500) as the other part of the collector 400 or the patch 500. At least one (the patch 500) of the first and second parts includes a projection part 510 in which a convex part 511 projected toward the other one (the electrode connection part 420) is formed. At least one part of the other one is arranged at a position nipping the lamination part 320 with the projection part 510 in the first direction. A gap 800 is formed at a position adjacent to the projection part 510 between the first and second parts. At a position overlapping with the projection part 510 when viewed from the first direction, a laser weld part 700 in which the first part and the lamination part 320 are welded with a laser is formed.SELECTED DRAWING: Figure 4

Description

The present invention relates to a power storage element including an electrode body having a laminated portion in which electrode plates are laminated, and a current collector connected to the laminated portion.

BACKGROUND ART Conventionally, a power storage element is widely known, which includes an electrode body having a laminated portion in which electrode plates are laminated, and a current collector, and in which the laminated portion of the electrode body and the current collector are laser welded. For example, Patent Document 1 discloses a secondary battery (power storage element) in which a tab group (laminated portion) of an electrode assembly (electrode body) and a conductive member (current collector) are laser welded.

JP 2019-61949 Publication

In the above-mentioned conventional energy storage element, when the laminated part of the electrode body and the current collector are joined by laser welding, if a gap is created in the area to be laser welded due to lifting of the electrode plate in the laminated part, the electrode body and the current collector There is a risk that the quality of welding with the electric body will deteriorate. For example, if there is a gap in the part to be laser welded, the melted part of the electrode plate will shrink and harden to fill the gap during welding, causing the plate to break at the interface between the molten part and the unmelted part. may occur. If a gap exists in the area to be laser welded, spatter or blowholes may occur during welding. These may reduce the quality of the bond between the laminated portion of the electrode body and the current collector.

An object of the present invention is to provide a power storage element that can improve the quality of bonding between the laminated portion of an electrode body and a current collector.

In order to achieve the above object, a power storage element according to one embodiment of the present invention includes an electrode body having a laminated portion in which electrode plates are laminated, and a current collector connected to the laminated portion. The laminated portion is sandwiched in the first direction between a first part that is a part of the current collector and a second part that is another part of the current collector or a backing plate. At least one of the first part and the second part has a protrusion formed with a convex part that protrudes toward the other, and at least a part of the other part is arranged in the first direction. A gap is formed at a position adjacent to the protrusion between the first part and the second part, and the protrusion is disposed at a position sandwiching the laminated part between the protrusion and the protrusion. A laser welded portion in which the first portion and the laminated portion are laser welded is formed at a position overlapping the protrusion.

A power storage element according to another aspect of the present invention includes an electrode body having a laminated portion in which electrode plates are laminated, and a current collector connected to the laminated portion, wherein the laminated portion is , disposed in a first direction in line with a first part that is a part of the current collector, and the first part has a protrusion in which a protrusion protrudes toward the laminated part. A gap is formed between the first part and the laminated part at a position adjacent to the protruding part, and a gap is formed between the first part and the laminated part at a position overlapping with the protruding part when viewed from the first direction. A laser welded portion is formed by laser welding the first portion and the laminated portion, and the laser welded portion is formed to penetrate the first portion and the laminated portion in the first direction.

The present invention can be realized not only as such a power storage element, but also in a method of manufacturing such a power storage element, a method of joining a laminated part of an electrode body and a current collector, or a method of joining a laminated part of an electrode body and a current collector. It can also be realized as a combination of

According to the electricity storage element of the present invention, it is possible to improve the quality of the bond between the laminated portion of the electrode body and the current collector.

FIG. 1 is a perspective view showing the appearance of a power storage element according to an embodiment. FIG. 2 is a perspective view showing the components arranged inside the container of the power storage element according to the embodiment. FIG. 3 is an exploded perspective view showing each component of the power storage element according to the embodiment. FIG. 4 is a front view and a sectional view showing the configuration of an electrode body, a current collector, a backing plate, and a laser welding part according to the embodiment. FIG. 5 is a cross-sectional view showing a method of forming a laser welded portion by laser welding the electrode body and current collector according to the embodiment. FIG. 6 is a sectional view showing the configuration of a laser welding part according to Modification 1 of the embodiment. FIG. 7 is a sectional view showing the configuration of a laser welding part according to a second modification of the embodiment. FIG. 8 is a cross-sectional view showing the configuration of a laser welding part according to modification 3 of the embodiment. FIG. 9A is a cross-sectional view showing the configuration of a laser welding part according to Modification 4 of the embodiment. FIG. 9B is a cross-sectional view showing the configuration of a laser welding part according to modification 5 of the embodiment.

A power storage element according to one aspect of the present invention includes an electrode body having a laminated portion in which electrode plates are laminated, and a current collector connected to the laminated portion, the laminated portion comprising: In a first direction, the first part is sandwiched between a first part that is a part of the current collector and a second part that is another part of the current collector or a backing plate; and at least one of the second parts has a protrusion formed with a convex part that protrudes toward the other, and at least a part of the other part is connected to the laminated part with the protrusion in the first direction. A gap is formed at a position adjacent to the protrusion between the first part and the second part, and a gap is formed at a position overlapping with the protrusion when viewed from the first direction. A laser welded portion is formed by laser welding the first portion and the laminated portion.

According to this, the electricity storage element is sandwiched in the first direction between the first part, which is a part of the current collector, and the second part, which is another part of the current collector or the backing plate. The method includes having a laminated portion disposed. At least one of the first part and the second part has a protrusion formed with a convex part that protrudes toward the other, and at least a part of the other part sandwiches the laminated part between the protrusion and the protrusion in the first direction. including being placed in a position. A gap is formed between the first part and the second part at a position adjacent to the protrusion, and the first part and the laminated part are laser welded at a position overlapping the protrusion when viewed from the first direction. This includes the formation of welds. That is, at least one of the first part and the second part (the current collector or the backing plate) is provided with a protrusion in which a convex part is formed that protrudes toward the other, and the protrusion is applied to the laminated part, and at least a part of the other By sandwiching the laminated portion between the members, the interface between the members is compressed. At this time, a gap will be formed between the first part and the second part at a position adjacent to the protruding part. This suppresses floating of the electrode plates in the laminated portion. That is, by suppressing the formation of a gap in the laser welding target site, it is possible to improve the quality of the bond between the laminated portion of the electrode body and the current collector.

The protrusion may have a recess that is recessed toward the protrusion at a position facing the protrusion.

According to this, since the protruding part has a recessed part recessed toward the protruding part at a position facing the protruding part, the thickness of the protruding part becomes thinner, so that the output during laser welding can be lowered. Therefore, it is possible to suppress the temperature rise in the laser welded portion. Therefore, it is possible to further improve the quality of the bond between the laminated portion of the electrode body and the current collector.

The thickness of the protruding portion of the protruding portion may be thinner than the thickness of a portion of at least one of the first portion and the second portion adjacent to the protruding portion.

According to this, the thickness of the protruding part of the protruding part is made thinner than the thickness of the part adjacent to the protruding part of at least one of the first part and the second part, thereby further reducing the output power during laser welding. It will be done. Therefore, the temperature rise in the laser welded portion can be further suppressed. Therefore, it is possible to further improve the quality of the bond between the laminated portion of the electrode body and the current collector.

One of the first part and the second part has a first convex part as the convex part, and the other of the first part and the second part is at a position facing the first convex part, It may have a larger plane than the first protrusion, or a second protrusion as the protrusion that protrudes toward the first protrusion.

According to this, one of the first part and the second part has the first convex part as the convex part, and the other of the first part and the second part has the first convex part at a position opposite to the first convex part. By having a flat surface larger than the first protrusion or a second protrusion that protrudes toward the first protrusion, the protrusion can be easily applied to the laminated part and the interface between the members can be easily be brought into contact. For this reason, floating of the electrode plate in the laminated portion is further suppressed, and the gap at the laser welding target area can be suppressed. Therefore, it is possible to further improve the quality of the bond between the laminated portion of the electrode body and the current collector.

In a second direction perpendicular to the first direction, a pair of the gaps may be formed at positions sandwiching the protrusion between the first part and the second part.

According to this, a pair of gaps are formed at positions sandwiching the protrusion between the first part and the second part in the second direction orthogonal to the first direction, so that the protrusion can be laminated more easily. assigned to the department. Therefore, the protrusion can be compressed in a more balanced manner. Therefore, it is possible to further improve the quality of the bond between the laminated portion of the electrode body and the current collector.

The laser welded portion may be formed to penetrate at least one of the first part and the second part in the first direction.

According to this, the laser welded part is formed by penetrating one of the first part and the second part in the first direction, so that the protrusion part in which the convex part protrudes toward the other part is formed. It will be formed through it. In other words, the floating of the electrode plates in the laminated portion is further suppressed, and the gap at the laser welding target area can be suppressed. Therefore, it is possible to further improve the quality of the bond between the laminated portion of the electrode body and the current collector.

A power storage element according to another aspect of the present invention includes an electrode body having a laminated portion in which electrode plates are laminated, and a current collector connected to the laminated portion, wherein the laminated portion is , disposed in a first direction in line with a first part that is a part of the current collector, and the first part has a protrusion in which a protrusion protrudes toward the laminated part. A gap is formed between the first part and the laminated part at a position adjacent to the protruding part, and a gap is formed between the first part and the laminated part at a position overlapping with the protruding part when viewed from the first direction. A laser welded portion is formed by laser welding the first portion and the laminated portion, and the laser welded portion is formed to penetrate the first portion and the laminated portion in the first direction.

According to this, the power storage element has a laminated part arranged in a first direction in line with a first part that is a part of the current collector, and the first part protrudes toward the laminated part. This includes having a protrusion formed with a convex portion. A gap is formed between the first part and the laminated part at a position adjacent to the protruding part, and the first part and the laminated part are laser welded at a position overlapping with the protruding part when viewed from the first direction. A portion is formed, and a laser weld is formed in a first direction through the first portion and the laminated portion. In other words, the first part, which is provided with a protruding part that projects toward the laminated part, is applied to the laminated part, and the laminated part is sandwiched between the first part and the jig during joining, so that the parts can be bonded together. Boundary surfaces are pressured. At this time, a gap will be formed between the first part and the laminated part at a position adjacent to the protrusion. As a result, lifting of the electrode plates in the laminated portion can be suppressed, and a gap in the laser welding target area can be suppressed. Therefore, it is possible to improve the quality of bonding between the laminated portion of the electrode body and the current collector.

Hereinafter, a power storage element according to an embodiment (and a modification thereof) of the present invention will be described with reference to the drawings. The embodiments described below are all inclusive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing steps, order of manufacturing steps, etc. shown in the following embodiments are merely examples, and do not limit the present invention. In each figure, dimensions etc. are not strictly illustrated. In each figure, the same or similar components are designated by the same reference numerals.

In the following description and drawings, the direction in which a pair of electrode terminals (positive electrode and negative electrode, the same shall apply hereinafter) of a power storage element, the direction in which a pair of current collectors are arranged, or the direction in which the short sides of the container face each other is referred to as the X axis. Define direction. The direction in which the long sides of the container face each other, the thickness direction of the container, the stacking direction of the electrode plates at the joint between the electrode body and the current collector (laser welding part), and the alignment direction of the current collector and the electrode body at the joint. , the direction in which the current collector, electrode body, and backing plate are lined up at the joint, or the direction in which the laser beam is irradiated at the joint is defined as the Y-axis direction. The direction in which the container body and the lid of the power storage element are lined up, the direction in which the electrode connection portions (legs) of the current collector extend, or the up-down direction is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect with each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the vertical direction, but for convenience of explanation, the Z-axis direction will be described as the vertical direction below.

In the following description, the X-axis plus direction refers to the arrow direction of the X-axis, and the X-axis minus direction refers to the opposite direction to the X-axis plus direction. The same applies to the Y-axis direction and the Z-axis direction. Hereinafter, the Y-axis direction will also be referred to as the first direction, and the X-axis direction will also be referred to as the second direction. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the directions or orientations are not strictly speaking. Two directions being orthogonal does not only mean that the two directions are completely orthogonal, but also that they are substantially orthogonal, even if there is a difference of a few percent. good. In the following description, when the expression "insulation" is used, it means "electrical insulation".

(Embodiment)
[1 General description of power storage element 10]
First, a general description of the power storage element 10 in this embodiment will be given using FIGS. 1 to 3. FIG. 1 is a perspective view showing the appearance of a power storage element 10 according to the present embodiment. FIG. 2 is a perspective view showing components arranged inside container 100 of power storage element 10 according to the present embodiment. Specifically, FIG. 2 is a perspective view showing the configuration with the container body 110 separated from the power storage element 10, and shows the state after the current collector 400 is joined to the electrode body 300. FIG. 3 is an exploded perspective view showing each component of the power storage element 10 according to the present embodiment. Specifically, FIG. 3 is an exploded perspective view showing components other than the container body 110 shown in FIG. 2, and shows a state before the current collector 400 is joined to the electrode body 300.

The power storage element 10 is a secondary battery (single battery) that can charge and discharge electricity, and specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The power storage element 10 is used as a battery for driving or starting an engine of a moving object such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. It's okay. Examples of the above-mentioned vehicles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel oil, liquefied natural gas, etc.) vehicles. Examples of the above-mentioned railway vehicles for electric railways include electric trains, monorails, linear motor cars, and hybrid electric trains equipped with both a diesel engine and an electric motor. The power storage element 10 may also be used as a stationary battery or the like used for home or business purposes.

The power 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 a capacitor. The power storage element 10 may be not a secondary battery but a primary battery that allows the user to use the stored electricity without charging it. Power storage element 10 may be a battery using a solid electrolyte. The power storage element 10 may be a pouch type power storage element. In this embodiment, a flat rectangular parallelepiped-shaped (prismatic) power storage element 10 is illustrated, but the shape of the power storage element 10 is not limited to the rectangular parallelepiped shape, and may be a cylinder shape, an elongated cylinder shape, or a shape other than a rectangular parallelepiped. It may also have a prismatic shape or the like.

As shown in FIG. 1, the power storage element 10 includes a container 100, a pair of electrode terminals 200 (a positive electrode and a negative electrode), and a pair of upper gaskets 210 (a positive electrode and a negative electrode). As shown in FIGS. 2 and 3, inside the container 100, there are a pair (positive electrode and negative electrode) of lower gaskets 220, an electrode body 300, and a pair (positive electrode and negative electrode) of current collectors 400 (404 and 405). ) and a pair (positive electrode and negative electrode) of backing plates 500 are housed. An electrolytic solution (non-aqueous electrolyte) is sealed inside the container 100, but illustration thereof is omitted. The type of electrolytic solution is not particularly limited as long as it does not impair the performance of the power storage element 10, and various types can be selected. In addition to the above-mentioned components, a spacer disposed on the side or below the electrode body 300, an insulating film that wraps around the electrode body 300, etc. may be disposed.

The container 100 is a rectangular parallelepiped-shaped (prismatic or box-shaped) case that includes a container body 110 with an opening formed therein and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member that constitutes the main body of the container 100 and has a bottom. The container body 110 has a pair of flat and rectangular short side walls 111 on both sides (short sides) in the X-axis direction, and a pair of flat and rectangular short side walls 111 on both sides (long sides) in the Y-axis direction. It has a long side wall portion 112 and a bottom wall portion 113 that is flat and rectangular in the negative Z-axis direction. The lid 120 is a rectangular plate-like member that constitutes the lid of the container 100, and is arranged to extend in the X-axis direction in the Z-axis plus direction of the container body 110. The lid body 120 includes a gas discharge valve 121 that releases the pressure inside the container 100 when the pressure rises excessively, and a liquid injection part 122 that injects electrolyte into the inside of the container 100. etc. are provided.

With this configuration, the container 100 has a structure in which the inside is sealed by housing the electrode body 300 and the like inside the container body 110 and then joining the container body 110 and the lid 120 by welding or the like. ing. The material of the container 100 (container body 110 and lid 120) is not particularly limited, and may be a weldable metal such as stainless steel, aluminum, aluminum alloy, or iron, or resin may be used.

The electrode body 300 is a power storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on a positive electrode base material layer which is a long strip-shaped current collecting foil made of aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on a negative electrode base material layer which is a long strip-shaped current collecting foil made of copper or a copper alloy. As the current collector foil, appropriately known materials such as nickel, iron, stainless steel, titanium, fired carbon, conductive polymer, conductive glass, Al--Cd alloy, etc. can be used. As the positive electrode active material and the negative electrode active material used in the positive electrode active material layer and the negative electrode active material layer, any known material can be used as appropriate as long as it is an active material capable of intercalating and deintercalating lithium ions. As the separator, a microporous sheet made of resin, a nonwoven fabric, or the like can be used.

The electrode body 300 has a laminated portion 320 in which electrode plates 301 are laminated. That is, the electrode body 300 is formed by laminating a positive electrode plate, a negative electrode plate, and a separator. Specifically, the electrode body 300 is formed by winding a separator between a positive electrode plate and a negative electrode plate. More specifically, in the electrode body 300, a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween so as to be offset from each other in the direction of the winding axis. The winding axis is a virtual axis that becomes the central axis when winding the positive electrode plate, negative electrode plate, etc., and in this embodiment, it is a straight line parallel to the X-axis direction passing through the center of the electrode body 300. It is. The positive electrode plate and the negative electrode plate each have a portion (active material layer non-forming portion) where the active material is not formed (coated) and the base material layer is exposed at the ends in the shifted direction.

As a result, the electrode body 300 has a positive electrode laminated portion 320 in which active material layer-free portions of the positive electrode plate are laminated and bundled at one end in the winding axis direction, and the other end in the winding axis direction. It has a negative electrode laminated portion 320 in which the active material layer-free portion of the negative electrode plate is laminated and bundled. The laminated portion 320 is a portion where electrode plates (positive electrode plates or negative electrode plates) are laminated in the lamination direction (Y-axis direction). In other words, the electrode body 300 includes an electrode body body part 310 that constitutes the body of the electrode body 300, and a pair of laminated parts 320 (a positive electrode and a negative electrode) that protrude from the electrode body body part 310 on both sides in the X-axis direction. ing. The electrode main body part 310 is an oval-shaped part (active material layer forming part) formed by winding the parts of the positive electrode plate and the negative electrode plate on which the active material layers are formed (coated) and the separator. . In this embodiment, an oval shape is illustrated as the cross-sectional shape of the electrode body 300 (electrode body main body portion 310), but the cross-sectional shape may be circular, elliptical, polygonal, or the like.

The electrode terminal 200 is a terminal member (a positive electrode terminal and a negative electrode terminal) that is electrically connected to the electrode body 300 via the current collector 400. In other words, the electrode terminal 200 is a metal terminal for guiding the electricity stored in the electrode body 300 to the external space of the electricity storage element 10 and for introducing electricity into the internal space of the electricity storage element 10 to store electricity in the electrode body 300. It is a manufactured member. The electrode terminal 200 is made of a conductive member such as metal such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminal 200 is connected (joined) to the current collector 400 by caulking or the like, and is attached to the lid 120.

Specifically, as shown in FIG. 3, the shaft portion 201 of the electrode terminal 200 is connected to the through hole 211 of the upper gasket 210, the through hole 123 of the lid body 120, and the through hole 221 of the lower gasket 220. The current collector 400 is fixed to the lid 120 together with the current collector 400 by being inserted into the through hole 413 of the current collector 400 and caulked. The method of connecting (joining) the electrode terminal 200 and the current collector 400 is not limited to caulking, but may include welding such as ultrasonic welding, laser welding, or resistance welding, or a mechanical method other than caulking such as screw fastening. Bonding or the like may also be used.

The upper gasket 210 is a plate-shaped and rectangular member (a positive electrode upper gasket and negative electrode upper gasket). A through hole 211 into which the shaft portion 201 of the electrode terminal 200 described above is inserted is formed in the center of the upper gasket 210. The lower gasket 220 is a plate-shaped and rectangular member (a positive electrode lower gasket and a negative electrode lower gasket). A through hole 221 into which the shaft portion 201 of the electrode terminal 200 described above is inserted is formed in the center of the lower gasket 220.

The upper gasket 210 and the lower gasket 220 may be made of any material as long as it has insulating properties, such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS). , polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoro It may be formed of an insulating member such as ethylene (PTFE), polyethersulfone (PES), ABS resin, or a composite material thereof.

The current collector 400 is connected to the laminated portion 320 of the electrode body 300. Specifically, the current collectors 400 are arranged on both sides of the electrode body 300 in the X-axis direction, are connected (joined) to the laminated portion 320 of the electrode body 300 and the electrode terminals 200, and are connected to the electrode body 300 and the electrode terminals 200. A current collecting member (a positive electrode current collector and a negative electrode current collector) having conductivity and rigidity that electrically connects the two. More specifically, the current collector 400 is a plate-like member that extends from the side wall of the container body 110 to the lid 120 and is bent along the side wall and the lid 120. The current collector 400 is fixedly connected (joined) to the lid 120. With this configuration, the electrode body 300 is held (supported) in a suspended state from the lid body 120 by the current collector 400, and shaking due to vibration, impact, etc. is suppressed. Although the material of the current collector 400 is not particularly limited, the positive electrode current collector 400 is made of aluminum or an aluminum alloy, like the positive electrode base material layer of the electrode body 300, and the negative electrode current collector 400 is made of aluminum or an aluminum alloy. Like the negative electrode base material layer of No. 300, it may be formed of copper, copper alloy, or the like.

As shown in FIG. 3, of the positive electrode and negative electrode current collectors 400, the current collector 404 in the positive direction of the X-axis and the current collector 405 in the negative direction of the X-axis have shapes that are symmetrical with respect to the YZ plane. are doing. Each current collector 400 (404 and 405) has a terminal connection portion 414 and an electrode connection portion 420 that is a leg extending from the terminal connection portion 414 in the negative Z-axis direction.

The terminal connection portion 414 is the base of the current collector 400 that is connected (joined) to the electrode terminal 200. Specifically, the terminal connection part 414 is arranged on the electrode terminal 200 side (upper side, Z-axis positive direction) of the current collector 400, and parallel to the XY plane in which the above-mentioned circular through hole 413 is formed. The electrode terminal 200 is electrically and mechanically connected (joined) to the electrode terminal 200. The electrode connection portion 420 is a leg portion of the current collector 400 that is connected (joined) to the electrode body 300. That is, the electrode connection part 420 is a part disposed on the electrode body 300 side (lower side, Z-axis negative direction) of the current collector 400, and is electrically and mechanically connected (joined) to the electrode body 300. . Specifically, the electrode connecting portion 420 is a long and flat portion extending in the negative Z-axis direction from the end of the terminal connecting portion 414 in the Y-axis positive direction, and It is disposed in the positive axis direction and joined to the laminated portion 320. The flat plate shape is not limited to a completely flat plate shape, and may have protrusions or holes, or may be partially chipped.

In this embodiment, the electrode connection portion 420, which is a part of the current collector 400, is an example of the first part, and the backing plate 500 is an example of the second part. The laminated part 320 is sandwiched between an electrode connecting part 420 (first part), which is a part of the current collector 400, and a backing plate 500 (second part) in the first direction (Y-axis direction). It is located. Specifically, the patch plate 500 is placed at a position where the electrode body 300 is sandwiched between the current collector 400 and the contact plate 500 is placed in a position where the electrode body 300 is sandwiched between the current collector 400 and the electrode body 300 together with the current collector 400. It is a member to be joined. In other words, the cover plate 500 is a cover that protects the laminated portion 320 and is placed at a position sandwiching the laminated portion 320 between the electrode connection portion 420 and the laminated portion 320 . The backing plate 500 has protrusions 510 in the Z-axis plus direction and the Z-axis minus direction, respectively.

Specifically, the backing plate 500 is a flat rectangular metal member that is arranged in the negative Y-axis direction of the laminated portion 320 and extends in the Z-axis direction along the laminated portion 320. The protruding portion 510 of the backing plate 500 is arranged to face the laminated portion 320 in the Y-axis direction. Although the material of the backing plate 500 is not particularly limited, the positive electrode backing plate 500 is made of aluminum or an aluminum alloy, etc., similar to the positive electrode base material layer of the electrode body 300, and the negative electrode backing plate 500 is made of aluminum or an aluminum alloy, etc. Like the base material layer, it may be formed of copper, copper alloy, or the like. The flat plate shape is not limited to a completely flat plate shape, and may have protrusions or holes, or may be partially chipped.

With such a configuration, the electrode connecting portion 420 and the laminated portion 320 are joined to the caul plate 500 with the laminated portion 320 sandwiched between the electrode connecting portion 420 and the caul plate 500, thereby forming the caul plate 500. A laser weld 700 (see FIG. 2) is formed on the protrusion 510. In this embodiment, two laser welded parts 700 are formed on two protrusions 510 aligned in the Z-axis direction for one electrode connection part 420. That is, two laser welds 700 are formed in one current collector 400, and four laser welds 700 are formed in one power storage element 10.

[2 Description of laser welding section 700]
[2.1 Description of configuration of laser welding section 700]
Next, the configuration of the laser welded portion 700 of the laminated portion 320 of the electrode body 300, the electrode connection portion 420 of the current collector 400, and the protrusion portion 510 of the backing plate 500 will be described in detail. FIG. 4 is a front view and a cross-sectional view showing the configuration of an electrode body 300, a current collector 400, a backing plate 500, and a laser welding part 700 according to the present embodiment. Specifically, (a) of FIG. 4 is an enlarged front view showing the laser welding part 700 shown in FIG. 2 and the configuration around it as viewed from the negative direction of the Y-axis. FIG. 4(b) is a sectional view showing the configuration of FIG. 4(a) taken along the IV(b)-IV(b) cross section. Although FIG. 4 shows the configuration of one of the laser welded parts 700 shown in FIG. 2 and its surroundings, the other laser welded parts 700 and their surroundings have similar structures. have.

As shown in these figures, the electrode connection part 420 of the current collector 400 is arranged in the Y-axis positive direction of the laminated part 320 of the electrode body 300, and the backing plate 500 is arranged in the Y-axis negative direction of the laminated part 320. As a result, a laser welded portion 700 is formed in which the electrode body 300, the current collector 400, and the backing plate 500 are joined. In addition to the protrusion 510 described above, the backing plate 500 has a flat portion 520 that is a flat portion (non-protrusion) at a position adjacent to the protrusion 510 . The protruding portion 510 is a circular portion (bulging portion) that bulges out from the flat portion 520 in the Y-axis plus direction when viewed from the Y-axis direction. The flat portion 520 is an annular portion disposed so as to surround the periphery (entire circumference) of the protrusion portion 510 when viewed from the Y-axis direction. The flat portion is not limited to a completely flat shape. That is, the flat portion may have an uneven shape to the extent that it can be called flat, may be partially chipped, or may be sloped.

As shown in FIG. 4, the protrusion 510 is formed at a position opposite to the protrusion 511 that protrudes in the positive direction of the Y-axis (toward the laminated portion 320), and the protrusion 510 It has a concave portion 512 that is concave toward. That is, the protrusion 510 has a recess 512 that is recessed toward the protrusion 511 at a position facing the protrusion 511 . The convex portion 511 is a circular convex portion that protrudes in the Y-axis positive direction from the Y-axis positive direction surface of the flat portion 520 when viewed from the Y-axis direction. The recess 512 is a circular recess that is recessed in the Y-axis positive direction from the surface of the flat portion 520 in the Y-axis negative direction when viewed from the Y-axis direction. The inner circumferential surface of the recessed portion 512 is smaller than the outer circumferential surface of the convex portion 511 when viewed from the Y-axis direction. In other words, the surface of the backing plate 500 in the negative direction of the Y-axis is recessed to form a recess 512, and the surface of the backing plate 500 in the positive direction of the Y-axis protrudes to form a convex portion at a position opposite to the recess 512. 511 is formed.

As shown in FIG. 4(b), the thickness of the protruding portion of the protruding portion 510 (thickness in the Y-axis direction) is equal to at least one of the electrode connecting portion 420 (first part) and the backing plate 500 (second part) In this embodiment, it is thinner than the thickness (thickness in the Y-axis direction) of the portion (flat portion 520 in this embodiment) adjacent to protrusion 510 of backing plate 500). In this way, at least one of the electrode connection portion 420 (first part) and the caul plate 500 (second portion) (the caul plate 500 in this embodiment) is connected to the other (the electrode connection portion 420 in this embodiment). It has a protrusion 510 in which a protrusion 511 is formed to protrude toward the terminal. At least a portion of the other (electrode connection portion 420) is arranged at a position sandwiching the laminated portion 320 between the protrusion portion 510 and the protrusion portion 510 in the first direction (Y-axis direction). Although the laminated portion 320 is pressed by the protruding portion 410 of the caul plate 500, the flat portion 520 of the caul plate 500 and the laminated portion 320 are not in contact with each other, leaving a gap. Since the laser welded portion 700 is formed on the protruding portion 510, there may or may not be a gap between the flat portion 520 and the laminated portion 320.

Laser welding section 700 is formed by laser welding. Therefore, the laser welded portion 700 has the shape of a welded portion formed by laser welding. Specifically, as shown in FIG. 4B, the laser welded portion 700 has a shape that tapers away from the surface onto which the laser beam is incident. In other words, in the laser weld 700, the size of the laser weld formed on the laser irradiated surface is larger than the size of the tip of the laser weld 700 formed at a position away from the laser beam. Specifically, when the laser is irradiated from the Y-axis minus direction to the Y-axis plus direction, the size of the laser weld formed on the surface of the recess 512 in the Y-axis minus direction (in the X-axis direction on the The width formed in the concave portion 512 of the laser welded portion 700 is larger than the size of the tip of the laser welded portion 700 (width of the tip of the laser welded portion 700 in the X-axis direction in the XY plane).

As shown in FIG. 4(b), one of the electrode connecting portion 420 (first part) and the backing plate 500 (second part) (the backing plate 500 in this embodiment) has the first part as the convex part 511. It has a convex portion 511. The other of the electrode connecting part 420 (first part) and the backing plate 500 (second part) (electrode connecting part 420 in the present embodiment) is located at a position facing the first convex part 511, It also has a large flat surface. Specifically, the electrode connecting portion 420, which faces the Y-axis plus direction surface of the convex portion (corresponding to the first convex portion) 511 of the protruding portion 510 with the laminated portion 320 in between, It is a plane with a large size (area) when viewed from the direction. As a result, the protruding portion 510 of the patch plate 500 can be more easily applied to the laminated portion 320, and the interface between the members (the interface between the current collector 400 and the electrode plate 301, the interface between the electrode plates 301, the contact The interface between the plate 500 and the electrode plate 301, or the interface between the current collector 400 and the backing plate 500) can be brought into contact more easily.

In the state where the protrusion 510 presses the laminated part 320 (the laser welded part 700 is formed), the protrusion 510 and the adjacent part between the electrode connection part 420 (first part) and the backing plate 500 (second part) A gap 800 is formed at the matching position. As shown in FIG. 4A, the gap 800 is formed in an annular shape so as to surround the circular protrusion 510 when viewed from the negative direction of the Y-axis. That is, the gap 800 is continuously formed over the entire circumference of the protrusion 510.

As shown in FIG. 4B, the gap 800 is a space disposed within the recess 330 formed in the laminated portion 320 by the protrusion 510. That is, the gap 800 is a space surrounded by the inner circumferential surface of the recess 330 formed in the laminated portion 320, the outer circumferential surface of the protruding portion 510, and the surface of the flat portion 520 in the Y-axis plus direction. The gap 800 is larger than the gap between the plurality of electrode plates 301 arranged between the convex part 511 of the protruding part 510 and the current collector 400, and is arranged between the flat part 520 and the current collector 400. This gap is larger than the gap between the plurality of electrode plates 301. The plurality of electrode plates 301 are electrode plates stacked to form a laminated portion 320. Thereby, the protruding portion 510 can be more easily applied to the laminated portion 320, so that the plurality of electrode plates 301 can be compressed more closely and in a well-balanced manner. Therefore, the laser welded portion 700 can be formed more easily.

The laser welded portion 700 is formed by laser welding the electrode connection portion 420 (first portion) and the laminated portion 320 at a position overlapping the protrusion 510 when viewed from the first direction (Y-axis direction). In other words, the laser welding portion 700 connects the protruding portion 510, the laminated portion 320, and the electrode in the portion where the protruding portion 510 of the patch plate 500, the laminated portion 320 of the electrode body 300, and the electrode connection portion 420 of the current collector 400 are overlapped. The portion 420 is a welded portion formed by laser welding. As shown in FIG. 4A, the laser welded portion 700 is formed at the center of the protrusion 510. As shown in FIG. As shown in FIG. 4B, the laser welded portion 700 penetrates the protruding portion 510 and the laminated portion 320 in the Y-axis direction, and extends in the Y-axis direction up to the electrode connection portion 420. ). Specifically, in the laser welding portion 700, the protruding portion 510 and the laminated portion 320 are overlapped in the portion where the protruding portion 510 of the patch plate 500, the laminated portion 320 of the electrode body 300, and the electrode connection portion 420 of the current collector 400 are overlapped. This is a laser welding mark formed by laser welding the electrode connecting portion 420 and the electrode connecting portion 420.

In the first direction (Y-axis direction), the laser welding part 700 is connected to at least one of the electrode connecting part 420 (the first part in this embodiment) and the backing plate 500 (the second part in this embodiment). In the embodiment, it is formed to penetrate through the backing plate 500). Specifically, the laser welded portion 700 is formed in a region where the electrode plates 301 are in contact with each other when viewed from the Y-axis direction. More specifically, the laser welded portion 700 penetrates from the Y-axis minus direction surface of the concave portion 512 of the protrusion portion 510, through the surface of the convex portion 511 that faces the laminated portion 320, penetrates the laminated portion 320, and passes through the electrode. It is formed over a part of the connecting portion 420 (a portion in the negative direction of the Y-axis). In other words, the laser welded portion 700 is a melting trace formed by melting the portions of the protruding portion 510, the laminated portion 320, and the electrode connection portion 420 in the negative Y-axis direction.

In this embodiment, the laser welding part 700 is formed up to the part of the electrode connection part 420 in the negative Y-axis direction, but it may be formed up to the center part of the electrode connection part 420 in the Y-axis direction, or 420 in the Y-axis direction. Specifically, the laser welding portion 700 may melt the surface of the electrode connection portion 420 facing the laminated portion 320 and may not penetrate through the electrode connection portion 420 or may melt the surface of the electrode connection portion 420 facing the lamination portion 320. It may also penetrate to the surface opposite to the surface (the surface of the electrode connection portion 420 in the positive direction of the Y-axis). At this time, laser welding marks may be formed on the surface of the electrode connection section 420 opposite to the surface facing the laminated section 320 (the surface of the electrode connection section 420 in the Y-axis positive direction).

[2.2 Description of method for forming laser welded portion 700]
Next, among the methods for manufacturing power storage element 10, a method for forming laser welded portion 700, that is, a method for joining electrode body 300 and current collector 400, will be described in detail. FIG. 5 is a cross-sectional view showing a method of joining electrode body 300 and current collector 400 to form laser welded portion 700 according to the present embodiment. Specifically, (a) in FIG. 5 shows a state before the jig 20 is applied to the patch plate 500 in the method for manufacturing the electricity storage element 10 (method for forming the laser welded portion 700), and (a) in FIG. b) shows a state in which the jig 20 is applied to the caul plate 500 to press the laminated portion 320, and FIG. 5(c) shows a laser welding process.

First, as shown in FIG. 5A, the electrode body 300 is placed between the backing plate 500 and the current collector 400. Specifically, the protruding portion 510 of the backing plate 500 and the electrode connection portion 420 of the current collector 400 sandwich the laminated portion 320 in which the electrode plates 301 of the electrode body 300 are laminated. More specifically, the surface of the convex part 511 of the protruding part 510 arranged in the negative direction of the Y-axis of the laminated part 320 and the electrode connection part 420 arranged in the positive direction of the Y-axis of the laminated part 320 connect the electrode plate. The laminated portion 320 is sandwiched in the laminated direction (Y-axis direction) of 301. A jig 20 for pressing the laminated portion 320 is arranged so as to face the surface of the backing plate 500 in the negative direction of the Y-axis. Specifically, the jig 20 is arranged so as to face the surface in the negative Y-axis direction of a flat portion 520, which is a flat portion (non-protruding portion) adjacent to the protruding portion of the backing plate 500 in the X-axis direction. be done.

As shown in FIG. 5(b), the jig 20 is applied to the backing plate 500 and the laminated portion 320 is pressed in the Y-axis direction to form a gap 800 at a position adjacent to the protrusion 510 in the X-axis direction. . Specifically, by pushing the backing plate 500 in the Y-axis positive direction by the jig 20, the surface of the convex portion 511 of the protruding portion 510 in the Y-axis positive direction (the surface facing the laminated portion 320) is aligned with the Y-axis. Pushed in the positive direction. As a result, the interface between the members facing the protrusion 510 (the interface between the current collector 400 and the laminated part 320, the interface between the laminated electrode plates 301 of the laminated part 320, and the interface between the members facing the protrusion 510), The interface between the portion 510 and the laminated portion 320) is compressed. As a result, the gap at the interface between the members becomes smaller, and a gap 800 is formed at a position adjacent to the protrusion 510 in the X-axis direction.

Next, as shown in FIG. 5C, as a laser welding process, the protruding portion 510 is Laser light L is irradiated toward the surface in the negative direction. Thereby, the caul plate 500, the electrode body 300, and the current collector 400 are laser welded, and a laser welded portion 700 is formed. Specifically, in the laser welding process, the laser beam L is irradiated from the surface of the concave portion 512 of the protruding portion 510 in the Y-axis negative direction, passes through the surface of the convex portion 511 in the Y-axis positive direction, and reaches the pole of the laminated portion 320. A laser welded portion 700 is formed by penetrating the region where the plates 301 are in contact with each other and melting a portion of the electrode connection portion 420 of the current collector 400. The laser welding marks of the laser welded portion 700 are formed on the surface of the recessed portion 512 in the negative direction of the Y-axis. In this embodiment, the laser welded portion 700 is formed at the center of the recess 512 of the protrusion 510 when viewed from the irradiation direction (Y-axis direction) of the laser beam L, but it does not have to be at the center.

The concave portion 512 of the protruding portion 510 is a concave portion that is recessed toward the Y-axis plus direction relative to the flat portion 520 that is a portion (non-protruding portion) adjacent to the protruding portion 510 of the backing plate 500 in the X-axis direction. Therefore, the thickness of the protruding portion of the protruding portion 510 (thickness in the Y-axis direction) is thinner than the thickness (thickness in the Y-axis direction) of the flat portion 520, which is a portion adjacent to the protruding portion 510. Since the stacked portion 320 is pressed by the protrusion 510, the distance between the protrusion 510 and the electrode connection portion 420 is smaller than the distance between the flat portion 520 and the electrode connection portion 420 in the Y-axis direction. In other words, the thickness of the laminated portion 320 is thinner than before being pressed by the protruding portion 510. In the Y-axis direction, since the thickness of the protruding portion 510 and the thickness of the laminated portion 320 are thin, the output of the laser beam L during laser irradiation can be lowered. Therefore, the temperature rise in the laser welded portion 700 can be suppressed.

In the Y-axis direction, the position of the protrusion 510 is lower than the position of the flat part 520 in the negative Y-axis direction (a recess 512 is formed in the protrusion 510). Thereby, the position of the laser beam L can be adjusted more accurately during laser irradiation using the recess 512 as a mark. As in this embodiment, even if the jig 20 does not have a space for laser irradiation that matches the size of the recess 512 of the protrusion 510, the position of the protrusion 510 can be determined using the recess 512 as a landmark. can be easily confirmed and the laser welded portion 700 can be formed.

[3. Explanation of effects]
As described above, in the first direction (Y-axis direction), the power storage element 10 according to the embodiment of the present invention has a first part (in this embodiment, an electrode connection part) that is a part of the current collector 400. 420) and a second part that is another part of the current collector 400 or the patch plate 500 (in this embodiment, the patch plate 500). There is. At least one of the first part and the second part (in this embodiment, the backing plate 500) has a protrusion in which a convex part 511 that protrudes toward the other part (in this embodiment, the electrode connection part 420) is formed. 510. At least a portion of the other (electrode connection portion 420) is arranged at a position sandwiching the laminated portion 320 between the protrusion portion 510 and the protrusion portion 510 in the first direction (Y-axis direction). A gap 800 is formed between the first part (electrode connection part 420) and the second part (covering plate 500) at a position adjacent to the protrusion part 510. A laser welded portion 700 in which the first portion (electrode connection portion 420) and the laminated portion 320 are laser welded is formed at a position overlapping the protrusion 510 when viewed from the first direction (Y-axis direction).

That is, a protrusion in which a protrusion 511 protruding toward the other (electrode connection part 420) is formed on at least one of the first part (electrode connection part 420) and the second part (pattern plate 500) (battling plate 500). By providing the portion 510 and applying it to the laminated portion 320 and sandwiching the laminated portion 320 with at least a portion of the other (electrode connection portion 420), the boundary surface between the members is compressed. At this time, a gap 800 is formed between the first part (electrode connection part 420) and the second part (covering plate 500) at a position adjacent to the protrusion part 510. As a result, the jig 20 easily presses each of the plurality of electrode plates 301 stacked in the stacked section 320 and fixes the electrode plates 301 with a higher surface pressure than the conventional structure. 301 is suppressed from floating. In other words, the formation of a gap in the laser welding target area is suppressed. Thereby, deformation of the electrode plate 301 during melting can be suppressed, and the quality of bonding between the laminated portion 320 of the electrode body and the current collector 400 can be improved. The gap 800 is larger than the gap between the plurality of electrode plates 301 arranged between the convex part 511 of the protruding part 510 and the current collector 400, and is arranged between the flat part 520 and the current collector 400. This gap is larger than the gap between the plurality of electrode plates 301. The laser welding portion 700 may be dotted, linear, or annular.

The protrusion 510 has a recess 512 that is recessed toward the protrusion 511 at a position facing the protrusion 511 . In this way, the thickness of the protrusion 510 in the first direction (Y-axis direction) is reduced because the protrusion 510 has the recess 512 that is recessed toward the protrusion 511 at a position facing the protrusion 511. , the output during laser welding can be lowered. This makes it possible to suppress the temperature rise in the laser welded portion 700, thereby further improving the quality of the bond between the laminated portion 320 of the electrode body 300 and the current collector 400. In this embodiment, the laser is irradiated toward the laminated part 320 from the second part having the protruding part 510 (in this embodiment, the caul plate 500), but the laminated part 320 is irradiated from the second part not having the protruding part 510. Even when laser irradiation is performed toward the target, the heat capacity can be reduced. Therefore, even when laser irradiation is performed from the second part that does not have the protruding part 510 toward the laminated part 320, the laser irradiation is performed from the first part that has the protruded part 510 toward the laminated part 320. A rise in temperature of the welded portion 700 can be suppressed.

The thickness of the protruding portion of the protruding portion 510 is determined by the thickness of at least one of the first part (in this embodiment, electrode connection part 420) and the second part (in this embodiment, backing plate 500) (in this embodiment, It is thinner than the thickness of the protruding portion 510 and the flat portion 520 of the backing plate 500). According to this, when laser irradiation is performed toward the laminated part 320 from the second part (the patch plate 500) having the protruding part 510, at least the first part (the electrode connection part 420) and the second part (the patch plate 500) By making the thickness of the protruding portion of the protruding portion 510 on one side (the patch plate 500) thinner than the thickness of the flat portion 520, the output during laser welding can be further reduced. Therefore, the temperature rise in the laser welded portion 700 can be further suppressed. Therefore, it is possible to improve the quality of the bond between the laminated portion 320 of the electrode body 300, the current collector, and 400.

If the first part has the protruding part 510 and the second part does not have the protruding part 510, the heat capacity can be lowered even when laser irradiation is performed from the second part toward the laminated part 320. Similarly to the case where laser irradiation is performed toward the laminated portion 320, the temperature rise in the laser welded portion 700 can be suppressed. The thickness of the protruding portion of the protruding portion 510 is preferably 30 to 80%, and preferably 40 to 80%, of the thickness of the flat portion 520, which is a portion of the backing plate 500 that is not a protruding portion (a portion adjacent to the protruding portion). More preferably, it is 60%, and even more preferably about 50%. If the thickness of the protruding portion of the protruding portion 510 is 30 to 80% of the thickness of the flat portion 520, temperature rise in the laser welded portion 700 can be suppressed by performing laser welding with a lower laser output. If the thickness of the protruding portion of the protruding portion 510 is 40 to 60% of the thickness of the flat portion 520, the temperature rise in the laser welded portion 700 can be further suppressed, and the strength of the protruding portion 510 can be maintained while the backing plate is removed. I can press 500. If the thickness of the protruding portion of the protruding portion 510 is approximately 50% of the thickness of the flat portion 520, the temperature rise in the laser welded portion 700 can be further suppressed, and the strength of the protruding portion 510 can be maintained while the patch plate 500 can exert pressure on these effects in a well-balanced manner.

The protruding portion of the protruding portion 510 is a portion of the protruding portion 510 that contacts the laminated portion 320 of the electrode body 300. The thickness of the protrusion 510 that is not laser welded may or may not be thin. Even if the protruding portion 510 has the convex portion 511 but does not have the concave portion 512, the thickness of the convex portion 511 in the first direction (Y-axis direction) is equal to or greater than the thickness of the flat portion 520. If it is thin, laser welding can be performed without increasing the laser output while pressing the laminated portion 320 with a higher surface pressure than in the conventional structure.

One of the first part (in this embodiment, electrode connection part 420) and the second part (in this embodiment, patch plate 500) has a convex part 511 (in this embodiment, patch plate 500). It has one convex portion 511). The other of the first part (electrode connecting part 420) and the second part (covering plate 500) (in this embodiment, the electrode connecting part 420) has the first convex part 511 at a position facing the first convex part 511. It has a larger plane. That is, one of the first part and the second part (the patch plate 500) has the first convex part 511, and the other part (electrode connection part 420) has the first convex part at a position facing the first convex part 511. It has a plane larger than 511.

As a result, the protruding portion 510 can be more easily applied to the laminated portion 320, and the interface between the members (the interface between the current collector 400 and the electrode plate 301, the interface between the electrode plates 301, the contact plate 500 and the electrode plate 301, or the interface between the current collector 400 and the backing plate 500). For this reason, the jig 20 easily presses each of the electrode plates 301 stacked in the stacked part 320 and fixes the stacked part with a higher surface pressure than the conventional structure. is suppressed. Therefore, the quality of the bond between the laminated portion 320 of the electrode body 300 and the current collector 400 can be further improved.

In the second direction (X-axis direction) orthogonal to the first direction (Y-axis direction), the first part (in this embodiment, electrode connection part 420) and the second part (in this embodiment, backing plate 500) ) A pair of gaps 800 are formed at positions sandwiching the protrusion 510 between the gaps 800 . According to this, in the second direction (X-axis direction) orthogonal to the first direction (Y-axis direction), the protrusion 510 between the first part (electrode connection part 420) and the second part (backing plate 500) By forming a pair of gaps 800 at positions sandwiching the protrusion 510, the protrusion 510 can be more easily applied to the laminated portion 320. Therefore, the protruding portion 510 can be compressed in a more balanced manner. Therefore, the quality of the bond between the laminated portion 320 of the electrode body 300 and the current collector 400 can be further improved.

Laser welding portion 700 is formed to penetrate through one of the above (in this embodiment, patch plate 500) in the first direction (Y-axis direction). According to this, the laser welded portion 700 is formed by penetrating at least one of the first part and the second part (in this embodiment, the patch plate 500) in the first direction (Y-axis direction). A convex portion 511 that protrudes toward the other side (electrode connecting portion 420 in this embodiment) is formed so as to penetrate through the formed protrusion portion 510 . Thereby, the laminated portion 320, which is fixed with a higher surface pressure than the conventional structure, can be more easily laser welded. Therefore, the quality of the bond between the laminated portion 320 of the electrode body 300 and the current collector 400 can be further improved.

[4 Description of modification]
Next, a modification of the above embodiment will be described. FIG. 6 is a cross-sectional view showing the configuration of a laser welding section 701 according to Modification 1 of the present embodiment. FIG. 7 is a cross-sectional view showing the configuration of a laser welding section 702 according to a second modification of the present embodiment. FIG. 8 is a cross-sectional view showing the configuration of a laser welding section 703 according to Modification 3 of the present embodiment. FIG. 9A is a cross-sectional view showing the configuration of a laser welding section 704 according to Modification 4 of the present embodiment. FIG. 9B is a cross-sectional view showing the configuration of laser welding parts 704 and 705 according to Modification 5 of the present embodiment. Specifically, FIGS. 6 to 9B are all diagrams corresponding to FIG. 4(b).

As shown in FIG. 6, a laser welded portion 701 in Modification 1 is formed in place of the laser welded portion 700 in the above embodiment. In the embodiment described above, laser welding portion 700 is laser welded from the negative direction of the Y-axis, but laser welding portion 701 is laser welded from the positive direction of the Y-axis. That is, the laser welding portion 701 has laser welding marks on the surface of the electrode connection portion 420 of the current collector 400 in the Y-axis positive direction.

The welding depth in the Y-axis direction of the laser welded portion 701 may be the same as that of the laser welded portion 700 or may be shallower than the laser welded portion 700. Although in FIG. 6 the laser welded portion 701 does not penetrate the protrusion 510 of the caul plate 500, the laser welded portion 701 may be formed to penetrate the caul plate 500. In other words, laser welding marks may be formed on the surface of the recess 512 of the protrusion 510 of the backing plate 500 in the negative Y-axis direction.

As shown in FIG. 7 , the electrode connection portion 421 of the current collector 401 in Modification 2 has a protrusion 410 . The patch plate 501 in this modification does not have the protrusion 510 in the above embodiment. That is, the protrusion may be formed on the current collector 401 or on the backing plate 501. Specifically, in FIG. 7, the laser welded portion 702 is irradiated with the laser from the surface of the recessed portion 412 of the protruding portion 410 in the negative Y-axis direction, penetrates the convex portion 411, penetrates the laminated portion 320, and is attached to the backing plate. It is formed by melting a part of 501.

The welding depth in the Y-axis direction of the laser welding part 702 may be the same as that of the laser welding part 700 or may be shallower than the laser welding part 700. In FIG. 7, the laser welded portion 702 does not penetrate the caul plate 501, but the laser welded portion 702 may be formed to penetrate the caul plate 501. The laser welding portion 702 may be formed by laser irradiation from the surface of the backing plate 501 in the Y-axis plus direction.

As shown in FIG. 8, the electrode connection portion 422 of the current collector 402 in Modification 3 has a protrusion 410 as in Modification 2 described above. That is, FIG. 8 shows the power storage element 10 from modification 2 shown in FIG. 7, with the backing plate 501 removed. In this modification, the laser welded portion 703 is formed to penetrate the protrusion 410 and the laminated portion 320, similarly to the second modification. Specifically, in FIG. 8, the laser welded portion 703 is formed by irradiating the laser from the surface of the concave portion 412 of the protruding portion 410 in the negative Y-axis direction, penetrating the convex portion 411, and penetrating the laminated portion 320. be done. The laser welding marks are formed on the surface of the recess 412 in the negative Y-axis direction and on the surface of the laminated portion 320 in the positive Y-axis direction.

The laser welded portion 703 as shown in FIG. 8 may be formed by removing the caul plate after laser welding. When the caul plate is made of a material with a high melting point such as tungsten, the caul plate can be removed even after laser welding, so the caul plate can be used many times for laser welding. Therefore, it is possible to reduce the number of parts and the weight of the power storage element. By reducing the area occupied by the components within the container 100, the effect of improving energy density can be obtained.

A method for forming laser welded portion 703 (method for manufacturing a power storage element) will be described with reference to FIG. 5 of the above embodiment. As shown in FIG. 5A, the laminated portion 320 is sandwiched between the protruding portion 410 of the current collector 402 and the backing plate in the Y-axis direction (first direction), and the jig 20 is It is placed in the negative direction of the axis. As shown in FIG. 5(b), the jig 20 approaches the backing plate so as to press the laminated portion 320 in the Y-axis direction, and reaches a position where the gap 800 is adjacent to the protrusion 410 in the X-axis direction. It is formed. As shown in FIG. 5C, the laser welded portion 703 is formed by irradiating the laser from the surface of the concave portion 412 of the protruding portion 410 in the negative Y-axis direction, penetrating the convex portion 411, and penetrating the laminated portion 320. Ru. At this time, since the caul plate is made of a material having a high melting point that will not be melted by laser irradiation, the laser welded portion 703 is not formed on the caul plate. As a result, a laser welded portion 703 without a caul plate as shown in FIG. 8 is formed.

The patch plate may be any member as long as it sandwiches the current collector 402 and the laminated portion 320 with the jig 20 during laser welding. The laser welding part 703 is formed by laser welding the laminated part 320 between the current collector 402 and a table-like member made of a material that has a high melting point and does not melt at the temperature during laser welding, and The current collector 402 and the laminated portion 320 may be formed by separating them from the table after laser welding. Even if the laser welded part 703 is formed by such a method, as shown in FIG. It suffices if it is formed to penetrate through the portion 410 and the laminated portion 320.

As shown in FIG. 8, a power storage element 10 according to modification 3 includes an electrode body 300 having a laminated part 320 on which electrode plates 301 are laminated, and a current collector 402 connected to the laminated part 320. Including being. The laminated part 320 includes being arranged in a state lined up with a first part (in this modification, the electrode connection part 422) which is a part of the current collector 402 in the first direction (Y-axis direction). . The first part (electrode connection part 422) has a protrusion part 410 in which a convex part 411 that protrudes toward the laminated part 320 is formed, and the protrusion between the first part (electrode connection part 422) and the laminated part 320 A gap 800 may be formed at a position adjacent to portion 410. A laser welded portion 703 in which the first portion (electrode connection portion 422) and the laminated portion 320 are laser welded is formed at a position overlapping with the protrusion 410 when viewed from the first direction (Y-axis direction). includes being formed so as to penetrate through the first part (electrode connection part 422) and the laminated part 320 in the first direction (Y-axis direction).

That is, the first part (electrode connecting part 422) provided with the protruding part 410 in which the convex part 411 that protrudes toward the laminated part 320 is applied to the laminated part 320, and the first part (electrode connecting part 422) and the jig 20 sandwich the laminated portion 320. As a result, the interface between the members (the interface between the current collector 400 and the electrode plate 301, the interface between the electrode plates 301, the interface between the patch plate 500 and the electrode plate 301, or the interface between the current collector 400 and the patch plate) 500) is compressed. At this time, a gap 800 is formed between the first part (electrode connection part 422) and the laminated part 320 at a position adjacent to the protrusion part 410.

The gap 800 is a space disposed within the recess 330 formed in the laminated portion 320 by the protrusion 410 . That is, the gap 800 is a space surrounded by the inner circumferential surface of the recess 330 formed in the laminated portion 320, the outer circumferential surface of the protrusion 410, and the surface of the flat portion 430 in the Y-axis plus direction. The gap 800 is larger than the gap between the plurality of electrode plates 301 arranged between the convex part 411 of the protruding part 410 and the current collector 402, and is arranged between the flat part 430 and the current collector 402. This gap is larger than the gap between the plurality of electrode plates 301. As a result, the jig 20 easily presses each of the plurality of electrode plates 301 stacked in the stacked part 320, and fixes the stacked part 320 with a higher surface pressure than the conventional structure. 301 is suppressed from floating. Therefore, it is possible to improve the quality of bonding between the laminated portion 320 of the electrode body 300 and the current collector 402.

As shown in FIG. 9A, the current collector 403 in Modification 4 has two electrode connection parts 423, and a protrusion is formed in each electrode connection part 423. Specifically, similar to the current collector 400 shown in FIG. 3, the current collector 403 includes a terminal connection portion 414 and two electrode connection portions ( For example, it has a leg portion) 423. One electrode connection part 423 arranged in the negative direction of the Y-axis is also referred to as an electrode connection part 4231, and the other electrode connection part 423 arranged in the positive direction of the Y-axis is also referred to as an electrode connection part 4232.

With the laminated part 320 sandwiched between the protruding part 4101 of the electrode connecting part 4231 and the protruding part 4102 of the electrode connecting part 4232, the laser is irradiated from the Y-axis minus direction surface of the recessed part 4121 of the protruding part 4101, and the laser welding part is welded. 704 is formed. That is, in the first direction (Y-axis direction), the laminated part 320 includes a first part (electrode connection part 4231) that is a part of the current collector 403 and a second part that is another part of the current collector 403. (electrode connection portion 4232). By compressing the laminated portion 320 in this manner, a gap 800 is formed at a position adjacent to each protrusion in the X-axis direction. In other words, one of the first part (electrode connecting part 4231) and the second part (electrode connecting part 4232) has the first convex part 4111 as a convex part, and the first part and the second part have the first convex part 4111 as a convex part. The other part (electrode connection part 4232) has a second protrusion 4112 as a protrusion that protrudes toward the first protrusion 4111 at a position facing the first protrusion 4111. Since the protrusion 4101 and the protrusion 4102 face each other in the Y-axis direction and sandwich the laminated part 320, the laminated part 320 can be compressed more strongly than before.

The laser welding part 704 may be formed by penetrating the surface of the recess 4122 of the protrusion 4102 of the electrode connection part 4232 in the Y-axis positive direction, or It may also be formed by laser irradiation from the directional surface. In this modification, the current collector 403 has two electrode connecting parts 423, the electrode connecting part 4231 has the protruding part 4101, and the electrode connecting part 4232 has the protruding part 4102. The combination of members sandwiching the two is not limited to this. The laminated portion may be sandwiched between the protrusion of the electrode connection portion of the current collector and the protrusion of the backing plate.

As shown in FIG. 9B, in modification 5, a laser welded portion 704 and a laser welded portion 705 are formed. Specifically, in this modification, as in modification 4, the current collector 403 has two electrode connection parts 423, and each electrode connection part 423 has a protrusion. The laser welded portion 704 is formed by laser irradiation from the surface of the recessed portion 4121 of the protruding portion 4101 of the electrode connection portion 4231 in the negative Y-axis direction. The laser welded portion 705 is formed by laser irradiation from the surface of the recessed portion 4122 of the protruding portion 4102 of the electrode connection portion 4232 in the Y-axis positive direction. Since the two electrode connecting portions 423 are provided with recesses (4121, 4122) of the protrusions (4101, 4102), respectively, laser irradiation is performed from the surface of the recess (4121, 4122) of either protrusion (4101, 4102). However, laser welding can be performed with low laser power. Even when the recess 412 is not provided, the laminated portion 320 is pressed more strongly by the convex parts (4111, 4112) of the protrusions (4101, 4102) than when the protrusions (4101, 4102) are not provided. Therefore, deformation of the foil during melting and deterioration of bonding quality can be more easily suppressed. Thereby, the quality of bonding between the electrode body 300 and the current collector 403 can be improved more easily.

(Other variations)
Although the power storage element and the method for manufacturing the same according to the embodiment of the present invention (including variations thereof) have been described above, the present invention is not limited to this embodiment. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all changes within the meaning and range equivalent to the scope of the claims. The other configurations of the modified example shown below are the same as those of the above embodiment, so detailed explanation will be omitted.

In the embodiment described above, there may or may not be a gap between the backing plate 500 and the laminated portion 320. In either case, since the protruding portion 510 of the backing plate 500 can press the laminated portion 320, the laminated portion 320 can be fixed with a higher surface pressure than in the conventional structure. Similarly, when the electrode connecting portion 421 has the protruding portion 410 as shown in Modification 2, there may or may not be a gap between the electrode connecting portion 421 and the laminated portion 320. good. The same applies to other modified examples.

In the above embodiment, the protrusion 510 has the recess 512 that is recessed toward the protrusion 511 at a position facing the protrusion 511. However, the protrusion 510 does not need to have the recess 512. good. Even in this case, the protrusion 510 can press the laminated part 320, and the laminated part 320 can be fixed with a higher surface pressure than in the conventional structure.

In the embodiment described above, the thickness of the protruding portion of the protruding portion 510 may be thinner than the thickness of the flat portion 520 adjacent to the protruding portion 510 in at least one of the first portion and the second portion. The thickness of the protruding portion of the protruding portion 510 does not need to be thinner than the thickness of the flat portion 520 adjacent to the protruding portion 510. That is, the thickness of the protruding portion of the protrusion 510 may be thicker than the thickness of the flat portion 520 adjacent to the protrusion 510, or may be the same as the thickness of the flat portion 520 adjacent to the protrusion 510. The protruding portion is a portion of the protruding portion that comes into contact with the laminated portion 320 of the electrode body 300, but the thickness of the protruding portion that does not form a laser weld may be thinner than the thickness of the portion adjacent to the protruding portion. It's fine and doesn't have to be thin. When laser irradiation is performed from the direction in which the second parts facing each other with the laminated part in between are arranged, the first part having the protruding part does not need to be penetrated, so the thickness of the protruding part may be thick.

In the above embodiment, one of the first part and the second part has the first convex part as the convex part 511, and the other of the first part and the second part is located at a position facing the first convex part. , it is also possible to have a second convex portion as a flat surface larger than the first convex portion, or a convex portion 511 that protrudes toward the first convex portion. There may not be a plane larger than the first protrusion at a position facing the first protrusion, and there may be no second protrusion. Even when the laminated portion 320 is sandwiched between the first convex portion and a plane smaller than the first convex portion, the laminated portion 320 can be compressed by the first convex portion, and the laminated portion 320 can be fixed with a higher surface pressure than the conventional structure. . The other of the first part and the second part may have a recess that is recessed toward the projection at a position facing the projection. If one of the first part and the second part has a convex part, the laminated part 320 can be sandwiched between the convex part and the concave part, and the laminated part 320 can be pressed by the convex part, with a surface pressure higher than that of the conventional structure. The effect that the laminated portion 320 can be fixed can be obtained.

In the embodiment described above, a pair of gaps 800 are provided at positions sandwiching the protrusion 510 between the first part and the second part in the second direction (X-axis direction) orthogonal to the first direction (Y-axis direction). It is said that it may be formed. More specifically, it is assumed that the gap 800 is continuously formed all around the protrusion 510 so as to surround the protrusion 510. The gap 800 may be located anywhere as long as it is adjacent to the protrusion 510 between the first part and the second part. The gap 800 may be formed intermittently at a position adjacent to the protrusion 510, and may not be formed in an annular shape. That is, the gap 800 may be formed so as to surround the laser welded portion 700, or may be formed only at one location adjacent to the protrusion 510. The gap 800 may be formed at two locations facing each other with the protrusion 510 in between. The second direction may be the X-axis direction or the Z-axis direction.

In the embodiment described above, the laser welded part 700 may be formed to penetrate at least one of the first part and the second part having the protrusion part 510 in the first direction (Y-axis direction). The laser weld portion 700 does not have to be formed through one side having the protrusion 510. The laser welded portion 700 may be formed by penetrating a current collector or a backing plate (which may be a clamping member) that does not have a protruding portion, and penetrating the laminated portion 320 in the first direction. A current collector or a patch plate that faces the current collector without a protrusion or a patch plate that does not have a protrusion with the laminated portion 320 in between has a protrusion. Also in this form, since the laminated portion 320 is pressed by the convex portion 511 of the protruding portion 510, the heat capacity can be lowered, and the temperature rise in the laser welded portion 700 can be suppressed. Therefore, it is possible to improve the quality of the bond between the laminated portion of the electrode body and the current collector.

In the embodiment described above, one laser welded portion 700 is formed. The number of laser welded portions 700 may not be one. More than one laser weld 700 may be formed. As shown in FIG. 9B, a laser weld 704 and a laser weld 705 may be formed. In FIG. 9B, the laser welded portion 704 and the laser welded portion 705 are formed by laser irradiation from the respective concave portions (4121, 4122) of the two electrode connection portions (4231, 4232). It may also be formed by laser irradiation from the electrode connection portion (eg 4231). Both the laser welding portion 704 and the laser welding portion 705 may be formed by laser irradiation from the surface of the recess 4121 of the electrode connection portion 4231 in the negative Y-axis direction. The laser welded portion 700 may be irradiated with laser in a circumferential manner according to the shape of the protruding portion 510, and the laser welded portion may be formed at two locations. In this embodiment, the laser welded portion 700 is formed at the center of the recess 512, but it may be formed at the protrusion and does not need to be formed at the center. The laser welding portion may be formed at two locations in the X-axis direction (second direction), or may be formed intermittently at points to form a circular shape.

In the embodiment described above, the current collector 400 has a shape including the terminal connection part 414 and the electrode connection part 420, but it may have a shape like a clip. The current collector 400 may be a member that sandwiches the laminated portion 320 in the Y-axis direction (first direction). The laminated portion 320 is arranged to be sandwiched between a first part that is a part of the clip and a second part that is another part of the clip. Even in such a case, since the laminated portion 320 is pressed by the convex portion of the protrusion, it is possible to improve the quality of the bond between the laminated portion of the electrode body and the current collector. The first part, which is a part of the clip, and the electrode connection part 420 of the current collector 400 may be overlapped in the Y-axis direction and joined together. With this configuration, electrode terminal 200 of power storage element 10 and current collector 400 can be connected after forming the laser welded portion.

In the embodiment described above, the current collector 403 includes a terminal connection portion 414 and two electrode connection portions (for example, leg portions) 423 extending from the terminal connection portion 414 in the negative Z-axis direction. In the current collector 403, a part of the electrode connection part 420 extending from the terminal connection part 414 in the negative Z-axis direction and a part of the backing plate 500 may be connected. The cover plate 500 and the electrode connection part 420 do not need to be separate bodies, and the cover plate 500 and the electrode connection part 420 may be integrally formed (integrated). Even if a part of the electrode connecting part 420 and a part of the backing plate 500 are connected, the laminated part 320 is pressed by the convex part 511 of the protruding part 510, so that the laminated part 320 of the electrode body 300 and the current collector The quality of bonding with the body 400 can be improved. By reducing the area occupied by the components within the container 100, the effect of improving energy density can be obtained. Since the number of parts is reduced, costs can be reduced.

In the embodiment described above, one electrode connection part 420 is provided on the current collector 400, one patch plate 500 is arranged for one electrode connection part 420, and two laser welded parts 700 are formed. It was decided that it would be done. The number of electrode connection parts 420 provided in the current collector 400, the number of laser welded parts 700 formed in one electrode connection part 420, and the number of backing plates 500 arranged in one electrode connection part 420 are as follows: Not particularly limited.

In the above embodiment, the protrusion 510, the convex part 511, the recess 512, the laser welded part 700, the gap 800, etc. have a circular shape when viewed from the Y-axis direction (first direction). . These shapes are not particularly limited, and may be elliptical, oval, rectangular, or other polygonal shapes when viewed from the Y-axis direction.

In the embodiment described above, the current collector 400, the electrode body 300, and the backing plate 500 are joined together, but members other than these may also be joined together. The backing plate 500 may not be provided, and the electrode body 300 and the current collector 400 may be joined.

In the embodiment described above, the electrode body 300 is a wound type electrode body in which the winding axis is parallel to the lid body 120. The electrode body 300 may be a wound type electrode body in which the winding axis is perpendicular to the lid body 120. The shape of the electrode body 300 is not limited to the wound type, but may also be a stacked type in which flat plates are laminated, or a shape in which the plates and/or separators are folded into a bellows shape (the separator is made into a bellows shape and a rectangular plate is formed). It may be a sandwiched form, a form in which the electrode plate and the separator are overlapped and then made into a bellows shape, etc.). The laminated portion 320 may be a tab protruding from the electrode body body portion 310 of the electrode body 300. Specifically, the laminated portion 320 may be a tab that protrudes from the electrode body 310 of the electrode body 300 toward the lid 120 and is integrally formed with the electrode body 310 . This tab may be a tab that projects from the electrode body portion 310 and away from the container body 110 in the X-axis direction.

In the embodiment described above, the above configuration is applied to all the laser welding parts 700, but the above configuration does not need to be applied to any of the laser welding parts 700. Not all laser welding parts 700 need to be provided with protrusions.

Embodiments constructed by arbitrarily combining the components included in the above embodiments and their modifications are also included within the scope of the present invention.

The present invention not only provides a method for manufacturing such a power storage element and can be realized as a power storage element, but also a method for joining an electrode body 300 and a current collector 400, a combination of an electrode body 300 and a current collector 400, and an electrode body. 300 and the current collector 400, or a combination of the laminated portion 320 of the electrode body 300 and the current collector 400.

The present invention can be applied to power storage elements such as lithium ion secondary batteries.

10 Energy storage element 20 Jig 100 Container 110 Container body 111 Short side wall 112 Long side wall 113 Bottom wall 120 Lid 200 Electrode terminal 201 Shaft 300 Electrode body 301 Plate 310 Electrode body 320 Laminated portion 330 Recess 400, 401, 402, 403, 404, 405 Current collector 410, 4101, 4102, 510 Projection 411 Projection 511, 4111 Projection (first projection)
4112 Convex part (second convex part)
412, 512, 4121, 4122 Recessed portion 414 Terminal connection portion 420, 421, 422, 423, 4231, 4232 Electrode connection portion 430, 520 Flat portion 500, 501 Backing plate 700, 701, 702, 703, 704, 705 Laser welding portion 800 gap

Claims (7)

A power storage element comprising an electrode body having a laminated part in which electrode plates are laminated, and a current collector connected to the laminated part,
The laminated portion is arranged in a state in which it is sandwiched in a first direction between a first part that is a part of the current collector and a second part that is another part of the current collector or a backing plate. ,
At least one of the first part and the second part has a protrusion in which a convex part protrudes toward the other,
At least a portion of the other is disposed at a position sandwiching the laminated portion between the protruding portion and the protruding portion in the first direction,
A gap is formed between the first part and the second part at a position adjacent to the protrusion,
A power storage element, wherein a laser welded portion in which the first portion and the laminated portion are laser welded is formed at a position overlapping with the protrusion when viewed from the first direction. The power storage element according to claim 1, wherein the protrusion has a recess that is recessed toward the protrusion at a position facing the protrusion. The electricity storage element according to claim 2, wherein the thickness of the protruding portion of the protruding portion is thinner than the thickness of a portion of at least one of the first portion and the second portion adjacent to the protruding portion. One of the first part and the second part has a first convex part as the convex part,
The other of the first part and the second part has a flat surface larger than the first protrusion, or a protrusion that protrudes toward the first protrusion, at a position facing the first protrusion. The electricity storage element according to any one of claims 1 to 3, having a second convex portion. Any one of claims 1 to 4, wherein a pair of gaps are formed at positions sandwiching the protrusion between the first part and the second part in a second direction orthogonal to the first direction. The energy storage element described in . The power storage element according to any one of claims 1 to 5, wherein the laser welded portion is formed to penetrate at least one of the first part and the second part in the first direction. A power storage element comprising an electrode body having a laminated part in which electrode plates are laminated, and a current collector connected to the laminated part,
The laminated portion is arranged in a first direction in line with a first portion that is a part of the current collector,
The first part has a protrusion in which a convex part protrudes toward the laminated part,
A gap is formed between the first part and the laminated part at a position adjacent to the protrusion part,
A laser welded portion in which the first portion and the laminated portion are laser welded is formed at a position overlapping the protrusion when viewed from the first direction,
The laser welded portion is formed to penetrate the first portion and the laminated portion in the first direction. Electricity storage element.

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