JP2016192285A - Power storage element and manufacturing method for power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage element that is able to obtain sufficient tensile strength between ultrasonically joined members, and to provide a manufacturing method therefor.SOLUTION: In a power storage element, a first member made of metal and a second member made of metal are ultrasonically joined while they are kept in face contact with each other, and the arithmetic average height Ra of the surface roughness of a joined surface of the first member disposed in face contact with the second member satisfies Ra≤0.3 μm. The joined surface of the first member is an electrode body composed of aluminum or an aluminum alloy and layered with an electrode. The second member is at least one of a collector and an abutting plate arranged between the collector and the electrode body.SELECTED DRAWING: None

Description

  The present invention relates to a power storage element in which metal members are ultrasonically bonded to each other, and a method for manufacturing the power storage element.

  Conventionally, a method of manufacturing a prismatic battery by ultrasonic welding of metal members is known (see Patent Document 1). In this manufacturing method, for example, a metal positive electrode or negative electrode and a metal current collector are ultrasonically welded.

  For example, when the prismatic battery is used in a vehicle or the like, the prismatic battery is required to have reliability under severe conditions such as vibration and heat being repeatedly applied repeatedly. For this reason, in recent years, higher tensile strength is demanded between the metal members that are ultrasonically bonded in the rectangular battery.

JP 2005-216825 A

  Therefore, an object of the present invention is to provide a power storage element capable of obtaining sufficient tensile strength between ultrasonically bonded metal members, and a method for manufacturing the power storage element.

The electricity storage device according to the present invention is:
A metal first member and a second member ultrasonically bonded to each other;
The arithmetic average height Ra of the surface roughness at the joint surface with the second member in the first member satisfies Ra ≦ 0.3 μm.

  According to this configuration, sufficient tensile strength is ensured between the first member and the second member, that is, the first member and the second member are firmly connected.

In addition, a method for manufacturing a power storage device according to the present invention includes:
Comprising ultrasonic bonding in a state where the first metal member and the second metal member are in surface contact with each other,
In the first member, the arithmetic average height Ra of the surface roughness at the joint surface in surface contact with the second member satisfies Ra ≦ 0.3 μm.

  According to this configuration, sufficient tensile strength can be obtained between the first member and the second member after ultrasonic bonding.

in this case,
If the joining surface of the first member is made of aluminum or an aluminum alloy, more sufficient tensile strength can be obtained between the first member and the second member after ultrasonic joining.

In the method of manufacturing the electricity storage device,
The first member is an electrode body in which electrodes are laminated,
The second member may be at least one of a current collector and a contact plate disposed between the current collector and the electrode body.

  According to such a configuration, it is possible to obtain a power storage element in which sufficient tensile strength is ensured between the electrode body and at least one of the current collector and the contact plate.

  As described above, according to the present invention, it is possible to provide a power storage element that can obtain a sufficient tensile strength between ultrasonically bonded members, and a method for manufacturing the power storage element.

FIG. 1 is a perspective view of a power storage device manufactured by a manufacturing method according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is an exploded perspective view of the power storage element. FIG. 4 is a perspective view showing a cover plate of the electricity storage element and members assembled to the cover plate. FIG. 5 is a perspective view for explaining an electrode, a separator, and an electrode body. FIG. 6 is a perspective view of a clip member of the electricity storage element. FIG. 7 is a cross-sectional view at the position VII-VII in FIG. FIG. 8 is a diagram showing a flow of a method for manufacturing the power storage element. FIG. 9 is a diagram for explaining ultrasonic bonding between an electrode body and a current collector by a horn and an anvil. FIG. 10 is a bottom view for explaining the shape of the holding surface of the horn. FIG. 11 is a front view for explaining the shape of the holding surface of the horn. FIG. 12 is a diagram showing the relationship between the surface roughness of a member to be ultrasonically bonded and the tensile strength. FIG. 13 is a perspective view for explaining a power storage device including the power storage element.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In addition, the name of each component (each component) of this embodiment is a thing in this embodiment, and may differ from the name of each component (each component) in background art.

  In the following, first, the power storage element will be described, and then the method for manufacturing the power storage element will be specifically described.

  As shown in FIGS. 1 to 5, the storage element includes an electrode body 2 including electrodes, a case 3 that houses the electrode body 2, and an external terminal 4 that is disposed outside the case 3. And an external terminal 4 that conducts. In addition to the electrode body 2, the case 3, and the external terminal 4, the power storage element 1 also includes a current collector 5 that electrically connects the electrode body 2 and the external terminal 4.

  2 and 5, the electrode body 2 includes a cylindrical core 21, a separator 25, and an electrode wound around the core 21 in a state of being insulated from each other by the separator 25, Have The electrode of the present embodiment has a positive electrode 23 and a negative electrode 24. In other words, the electrode body 2 is formed by being wound around the core 21 in a state where the positive electrode 23 and the negative electrode 24 are laminated via the separator 25. When the lithium ions move between the positive electrode 23 and the negative electrode 24 through the separator 25 in the electrode body 2, the power storage device 1 is charged and discharged.

  The positive electrode 23 has a metal foil and a positive electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is an aluminum foil, for example. The positive electrode 23 has a non-covered portion (a portion where the positive electrode active material layer is not formed) 231 of the positive electrode active material layer at one edge portion in the width direction that is the short direction of the band shape. A portion of the positive electrode 23 where the positive electrode active material layer is formed is referred to as a covering portion 232.

  The positive electrode active material layer includes a positive electrode active material and a binder. The positive electrode active material of this embodiment is a lithium metal oxide, for example. Moreover, the binder of this embodiment is a polyvinylidene fluoride, for example.

  The negative electrode 24 has a metal foil and a negative electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is a copper foil, for example. The negative electrode 24 has a non-covered portion (negative electrode active material layer) of the negative electrode active material layer formed on the other edge portion in the width direction that is the short direction of the belt shape (on the side opposite to the non-covered portion 231 of the positive electrode 23). 241). The width of the covering portion (the portion where the negative electrode active material layer is formed) 242 of the negative electrode 24 is larger than the width of the covering portion 232 of the positive electrode 23.

  The negative electrode active material layer includes a negative electrode active material and a binder. The negative electrode active material of this embodiment is non-graphitizable carbon, for example. Moreover, the binder of this embodiment is a polyvinylidene fluoride, for example.

  The separator 25 is a strip-shaped member having insulating properties. The separator 25 of this embodiment is disposed between the positive electrode 23 and the negative electrode 24 to insulate between the positive electrode 23 and the negative electrode 24. The separator 25 holds the electrolytic solution in the case 3. Thereby, at the time of charging / discharging of the electrical storage element 1, lithium ion moves between the positive electrode 23 and the negative electrode 24 which are laminated | stacked alternately on both sides of the separator 25. FIG. This separator 25 is comprised by porous membranes, such as polyethylene, a polypropylene, a cellulose, polyamide, for example.

  The width of the separator (the dimension of the strip shape in the short direction) is slightly larger than the width of the covering portion 242 of the negative electrode 24. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24 that are overlapped with each other so that the covering portions 232 and 242 are overlapped with each other in the width direction. At this time, the non-covered portion 231 of the positive electrode 23 and the non-covered portion 241 of the negative electrode 24 do not overlap. That is, the non-covered portion 231 of the positive electrode 23 protrudes in the width direction from the region where the positive electrode 23 and the negative electrode 24 overlap, and the non-covered portion 241 of the negative electrode 24 extends from the region where the positive electrode 23 and the negative electrode 24 overlap in the width direction ( It protrudes in a direction opposite to the protruding direction of the non-covered portion 231 of the positive electrode 23. The electrode body 2 is formed by winding the positive electrode 23, the negative electrode 24, and the separator 25 in a state of being laminated in this manner. The portion where only the uncovered portion 231 of the positive electrode 23 or the uncovered portion 241 of the negative electrode 24 is stacked constitutes the uncovered stacked portion 26 in the electrode body 2.

  The uncoated laminated portion 26 is a portion that is electrically connected to the current collector 5 in the electrode body 2. The uncoated laminated portion 26 of the present embodiment has two portions (see FIG. 3 and FIG. 5) sandwiching the hollow portion 27 (see FIGS. 3 and 5) when viewed in the winding center direction of the wound positive electrode 23, negative electrode 24, and separator 25. The undivided uncoated laminate portion 261 is divided.

  The uncoated laminated portion 26 configured as described above is provided on each electrode of the electrode body 2. That is, the non-coated laminated portion 26 in which only the non-coated portion 231 of the positive electrode 23 is laminated constitutes the non-coated laminated portion of the positive electrode in the electrode body 2, and the non-coated laminated portion in which only the non-coated portion 241 of the negative electrode 24 is laminated. 26 constitutes an uncoated laminated portion of the negative electrode in the electrode body 2.

  As shown in FIGS. 1 to 3, the case 3 includes a case main body 31 having an opening and a lid plate 32 that closes (closes) the opening of the case main body 31. The case 3 houses the electrolytic solution in the internal space 33 (see FIG. 2) together with the electrode body 2 and the current collector 5 and the like. Case 3 is formed of a metal having resistance to the electrolytic solution. The case 3 of the present embodiment is formed of an aluminum metal material such as aluminum or an aluminum alloy, for example.

  The case 3 is formed by joining the opening peripheral edge 34 of the case main body 31 and the cover plate 32 (in the example of the present embodiment, the peripheral edge of the cover plate 32) in an overlapped state. In the case 3, an internal space 33 is defined by the case main body 31 and the lid plate 32. In the electricity storage device 1 of the present embodiment, the opening peripheral edge 34 of the case body 31 and the peripheral edge of the lid plate 32 are joined by laser welding.

  The case main body 31 includes a plate-like closing part 311 and a cylindrical body part 312 connected to the periphery of the closing part 311.

  The closing portion 311 is located at the lower end of the case main body 31 when the case main body 31 is arranged so that the opening faces upward (that is, it becomes the bottom wall of the case main body 31 when the opening faces upward). ) Part. The blocking part 311 has a rectangular shape when viewed in the normal direction of the blocking part 311.

  In the following, as shown in FIG. 1 and FIG. 2, the long side direction of the blocking portion 311 is the X-axis direction in the orthogonal coordinates, and the short side direction of the blocking portion 311 is the Y-axis direction in the rectangular coordinates. The line direction is taken as the Z-axis direction in orthogonal coordinates.

  The body portion 312 of the present embodiment has a rectangular tube shape. Specifically, the body portion 312 has a flat rectangular tube shape. The body portion 312 has a pair of long wall portions 313 extending from the long side at the periphery of the closing portion 311 and a pair of short wall portions 314 extending from the short side at the periphery of the closing portion 311. A flat rectangular tube-shaped body portion 312 is formed by connecting the ends of the short wall portion 314 corresponding to the pair of long wall portions 313 (specifically, facing each other in the Y-axis direction).

  As described above, the case body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end portion in the opening direction (Z-axis direction) is closed.

  The lid plate 32 is a plate-like member that closes the opening of the case body 31. Specifically, the cover plate 32 contacts the case body 31 so as to close the opening of the case body 31. More specifically, the peripheral edge portion of the cover plate 32 is overlapped with the open peripheral edge portion 34 (see FIG. 3) of the case main body 31 so as to close the opening of the case main body 31. The case 3 is configured by laser welding the cover plate 32 and the case body 31 in a state where the opening peripheral edge 34 and the cover plate 32 are overlapped. The cover plate 32 has a contour shape corresponding to the opening peripheral edge 34 of the case body 31 when viewed in the Z-axis direction. That is, the lid plate 32 is a rectangular plate material that is long in the X-axis direction when viewed in the Z-axis direction.

  The external terminal 4 is a part that is electrically connected to an external terminal of another power storage element or an external device. The external terminal 4 is formed of a conductive member. For example, the external terminal 4 is formed of a highly weldable metal material such as an aluminum-based metal material such as aluminum or an aluminum alloy, or a copper-based metal material such as copper or a copper alloy. As shown in FIGS. 1 to 4, the external terminal 4 has a connection surface 41 to which a bus bar or the like can be welded. The connection surface 41 of this embodiment is a plane.

  The collector 5 is arrange | positioned in the case 3 as shown in FIGS. 2-4, and is connected with the electrode body 2 directly or indirectly so that electricity supply is possible. The current collector 5 of the present embodiment is connected to the electrode body 2 via a clip member (pad plate) 6 so as to be energized. In other words, the power storage element 1 includes a current collector 5 and a clip member 6 that connects the electrode body 2 and the current collector 5 so as to allow energization.

  The current collector 5 is formed of a conductive member. The current collector 5 is disposed along the inner surface of the case 3 (see FIG. 2). The current collector 5 of the present embodiment connects the external terminal 4 and the clip member 6 so as to be energized. Specifically, the current collector 5 includes a first connection portion 51 that is connected to the external terminal 4 so as to be energized, and a second connection portion 52 that is connected to the electrode body 2 (specifically, the clip member 6) so as to be energized. And a bent portion 53 that connects the first connection portion 51 and the second connection portion 52. In the current collector 5, the bent portion 53 is disposed near the boundary between the lid plate 32 and the case body 31 in the case 3, the first connection portion 51 extends from the bent portion 53 along the lid plate 32, and the second The connecting portion 52 extends from the bent portion 53 along the short wall portion 314. That is, the current collector 5 is formed in an L shape. The current collector 5 of the present embodiment is formed by bending a plate-shaped metal material cut into a predetermined shape.

  The first connection portion 51 is a plate-like portion extending from the bent portion 53 along the inner surface of the case 3 (lid plate 32) while being insulated from the case 3 (specifically, the lid plate 32).

  The second connection portion 52 is connected to the electrode body 2 (in this embodiment, the non-covered laminated portion 26 of the electrode body 2 through the clip member 6) in a conductive manner. Specifically, the second connection portion 52 extends from the bent portion 53 along the inner surface of the case 3 (short wall portion 314) while being insulated from the case 3 (specifically, the short wall portion 314). The second connection portion 52 has at least one joining piece 55 that extends from the vicinity of the short wall portion 314 toward the uncoated laminated portion 26 and extends in the same direction as the second connection portion 52. The joining piece 55 is joined to the clip member 6. The joining piece 55 of this embodiment is joined to the clip member 6 by ultrasonic joining, for example.

  The second connection part 52 has two joining pieces 55 and 55. Specifically, the second connection portion 52 has two joining pieces 55 extending in the Z-axis direction on both sides of the opening so as to define an opening provided in the center in the Y-axis direction. That is, the second connection portion 52 includes a joining piece 55 to be joined to the clip member 6 sandwiching one of the two uncoated laminated portions 261 in each uncoated laminated portion 26, and the two uncoated laminated portions. And a joining piece 55 joined to the clip member 6 sandwiching the other of the portions 261.

The arithmetic mean height (arithmetic mean roughness) Ra of the surface roughness at the joint surface of each joint piece 55 with the clip member 6 (surface joined with the clip member 6 by ultrasonic joining) satisfies Ra ≦ 0.3 μm. ing. Here, the arithmetic average height Ra is one of the parameters representing the surface roughness defined in the Japanese Industrial Standard (JIS), and only the reference length is extracted from the roughness curve in the direction of the average line, When the X axis is taken in the direction of the average line of the extracted portion, the Y axis is taken in the direction of the vertical magnification, and the roughness curve is expressed by y = f (x), the value obtained by the following equation (1) is It is expressed in micrometer (μm).

  The current collectors 5 configured as described above are arranged on the positive electrode side and the negative electrode side of the electrode body 2, respectively. In the power storage device 1 of the present embodiment, the current collectors 5 are disposed in the case 3 in the vicinity of the uncovered laminated portion 26 of the electrode body 2 and in the vicinity of the uncoated laminated portion 26 of the negative electrode of the electrode body 2. Is done.

  The positive electrode current collector 5 and the negative electrode current collector 5 are formed of different materials. The positive electrode current collector 5 of the present embodiment is formed of, for example, aluminum or an aluminum alloy, and the negative electrode current collector 5 is formed of, for example, copper or a copper alloy. The positive electrode current collector 5 and the negative electrode current collector 5 may be formed of the same material.

  As shown in FIGS. 3, 4, 6 and 7, the clip member 6 includes a positive electrode 23 or a non-coated laminated portion 26 (specifically, a non-coated laminated portion 261 which is divided into two). The negative electrode 24 is sandwiched so as to be bundled. Thereby, the clip member 6 makes the positive electrodes 23 or the negative electrodes 24 laminated in the non-coated laminated portion 26 conductive. Specifically, the clip member 6 includes a pair of opposing pieces 61 that are opposed to each other with the uncoated laminated portion 261 (the laminated positive electrode 23 or the negative electrode 24 laminated) divided into the uncovered laminated portion 26, and the corresponding pieces 61. And a connecting portion 62 that connects one end portions to each other. The clip member 6 is formed of a conductive member. The clip member 6 of this embodiment is formed of the same metal material as the current collector 5 to be connected. That is, the clip member 6 that sandwiches the bisected uncoated laminate portion 261 of the positive electrode is formed of, for example, aluminum or an aluminum alloy, and the clip member 6 that sandwiches the bisected uncoated laminate portion 261 of, for example, copper or Formed of copper alloy. The clip member 6 is formed by bending a plate-shaped metal material so that the cross section has a U-shape (see FIG. 7). In the electricity storage device 1 of the present embodiment, two clip members 6 are disposed on the positive electrode of the electrode body 2, and two clip members 6 are disposed on the negative electrode of the electrode body 2.

  The arithmetic average height (arithmetic average roughness) Ra of the surface roughness in each clip member 6 satisfies Ra ≦ 0.3 μm. Note that the entire surface of the clip member 6 does not have to satisfy Ra ≦ 0.3 μm, and the clip member 6 is a bonding surface in ultrasonic bonding with at least the current collector 5 (specifically, the bonding piece 55), In addition, it is only necessary that Ra ≦ 0.3 μm be satisfied at the bonding surface in the ultrasonic bonding with the electrode body 2 (specifically, the bisected uncoated laminated portion 261).

  The power storage element 1 also includes an insulating member 7 that insulates the electrode body 2 from the case 3. As shown in FIGS. 2 and 3, the insulating member 7 of the present embodiment is a bag-like member disposed between the case 3 (specifically, the case body 31) and the electrode body 2. The insulating member 7 is formed in a bag shape by bending an insulating sheet-like member cut into a predetermined shape. In the electric storage element 1, the electrode body 2 (specifically, the electrode body 2 and the current collector 5) accommodated in the bag-like insulating member 7 is accommodated in the case 3.

  Next, a method for manufacturing the above-described power storage element 1 will be described with reference to FIGS.

  The electrode body 2 is formed by winding the positive electrode 23 and the negative electrode 24 around the core 21 in a state where the positive electrode 23 and the negative electrode 24 are stacked via the separator 25 (step S1). When the electrode body 2 is formed, the electrode body 2 and the current collector 5 are connected so as to be conductive by ultrasonic bonding (step S2). In the electricity storage device 1 of the present embodiment, the current collector 5 is indirectly connected to the electrode body 2 through the clip member 6 so as to be conductive. Details are as follows.

  Each of the two uncoated laminated portions 261 of the electrode body 2 is sandwiched between the clip members 6. Then, as shown in FIG. 9, the clip member 6 in a state of sandwiching the bisected uncoated laminated portion 261 and the current collector 5 (specifically, the joining piece 55 of the current collector 5) are in surface contact. In this state, the horn 9 is sandwiched between the anvil 8 and the horn 9 is ultrasonically vibrated. Accordingly, the positive electrode 23 or the negative electrode 24 (in detail, the non-covered portions 231 and 241) stacked in the halved uncoated stacked portion 261, the bisected uncovered stacked portion 261 and the clip member 6, and the clip member 6 and the joining piece 55 are joined (ultrasonic joining), respectively.

  The sandwiching surfaces of the horn 9 and the anvil 8 used at this time (surfaces sandwiching the member to be ultrasonically bonded) have, for example, a plurality of quadrangular pyramid-shaped convex portions 10 as shown in FIGS. The height of each quadrangular pyramid-shaped convex part 10 is 0.5 mm or less, and these convex parts 10 are arranged and arranged in the rectangular region 100. The short side of this rectangular area is 2 to 3 mm, and the long side is about 10 mm. The amplitude of the horn 9 is, for example, 64 μm at the maximum and 24 μm at the minimum in the Z-axis direction, and the frequency is 20 kHz. The vibration time of the horn 9 during ultrasonic bonding is 0.6 seconds or less at the maximum and 0.4 seconds or less at the minimum.

  Next, the external terminal 4 and the current collector 5 ultrasonically bonded to the electrode body 2 are assembled to the cover plate 32 (step S3). Subsequently, the electrode body 2 and the current collector 5 are covered with the insulating member 7 (step S4), and the electrode body 2 and the current collector 5 and the like covered with the insulating member 7 are inserted into the case body 31 (see FIG. Step S5). Thereby, the opening of the case body 31 is closed by the cover plate 32 to which the electrode body 2 and the current collector 5 are assembled. Then, in a state where the peripheral edge portion of the cover plate 32 overlaps the opening peripheral edge portion 34 of the case body 31, the peripheral edge portion and the opening peripheral edge portion 34 are welded (in the example of this embodiment, laser welding) (step S6). ). Thereby, the electrical storage element 1 is completed.

  According to the manufacturing method of the electricity storage device 1 described above, the respective joining surfaces of the joining piece 55 and the clip member 6 (surfaces that are in surface contact when ultrasonic joining), and the non-divided non-divergence in the clip member 6 are performed. Since the arithmetic average height Ra of the surface roughness at the joint surface with the coating laminated portion 261 satisfies Ra ≦ 0.3 μm, it is between the electrode body 2 and the current collector 5 (specifically, the current collector 5 Thus, the electricity storage device 1 in which sufficient tensile strength is secured between the joining piece 55 and the clip member 6, and between the bisected uncoated laminated portion 261 and the clip member 6 is obtained.

  Further, in the electricity storage device 1 of the present embodiment, the positive electrode uncoated laminated portion 26 of the electrode body 2, the clip member 6 disposed on the positive electrode of the electrode body 2, and the current collector 5 connected to the clip member 6. Are both made of aluminum or an aluminum alloy. For this reason, more sufficient tensile strength is obtained between the electrode body 2 and the clip member 6 after ultrasonic bonding, and between the clip member 6 and the current collector 5.

  Here, in order to confirm the effect of the method for manufacturing the electricity storage device 1 of the above embodiment, the arithmetic average height Ra of the surface roughness on the joint surface of the member to be ultrasonically bonded is changed, and the same as the above embodiment Ultrasonic bonding was performed using the horn 9 and the anvil 8, and the tensile strength between the ultrasonic bonded members was measured. The result is shown in FIG. From this result, it was confirmed that sufficient tensile strength can be obtained between the ultrasonically bonded members when the arithmetic average height Ra of the surface roughness on the bonding surface satisfies Ra ≦ 0.3.

  In addition, the electrical storage element of this invention and the manufacturing method of an electrical storage element are not limited to the said embodiment, Of course, in the range which does not deviate from the summary of this invention, a various change can be added. For example, the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of an embodiment can be deleted.

  The specific configuration of the metal member to be ultrasonically bonded is not limited. The member connected by ultrasonic bonding should just be a metal member (a 1st member and a 2nd member) which has a bonding surface which can be surface-contacted. In addition, the ultrasonic bonding may not be performed by bonding members through which current flows, that is, by joining members without current flowing after bonding.

  Moreover, in the said embodiment, although the case where the electrical storage element 1 was used as a nonaqueous electrolyte secondary battery (for example, lithium ion secondary battery) which can be charged / discharged was demonstrated, the kind and magnitude | size (capacity | capacitance) of the electrical storage element 1 were demonstrated. Is optional. Moreover, in the said embodiment, although the lithium ion secondary battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the present invention can be applied to various secondary batteries, other primary batteries, and power storage elements of capacitors such as electric double layer capacitors.

  The power storage element (for example, battery) 1 may be used in a power storage device 11 (a battery module when the power storage element is a battery) 11 as shown in FIG. The power storage device 11 includes at least two power storage elements 1 and a bus bar member 12 that electrically connects two (different) power storage elements 1 to each other. In this case, the technique of the present invention only needs to be applied to at least one power storage element 1.

  DESCRIPTION OF SYMBOLS 1 ... Power storage element, 2 ... Electrode body, 21 ... Core, 23 ... Positive electrode, 24 ... Negative electrode, 231, 241 ... Uncovered part, 232, 242 ... Covered part, 25 ... Separator, 26 ... Uncoated laminated part, 261 ... undivided uncoated laminated part, 27 ... hollow part, 3 ... case, 31 ... case main body, 311 ... closed part, 312 ... trunk part, 313 ... long wall part, 314 ... short wall part, 32 ... lid plate, 33 DESCRIPTION OF SYMBOLS Internal space 34 ... Opening peripheral edge part 4 ... External terminal 41 ... Connection surface 5 ... Current collector 51 ... First connection part 52 ... Second connection part 53 ... Bending part 55 ... Joining piece, DESCRIPTION OF SYMBOLS 6 ... Clip member, 61 ... Opposing piece, 62 ... Connection part, 7 ... Insulating member, 8 ... Anvil, 9 ... Horn, 11 ... Power storage device, 12 ... Bus bar member

Claims (4)

A metal first member and a second member ultrasonically bonded to each other;
In the first member, the arithmetic average height Ra of the surface roughness at the joint surface with the second member satisfies Ra ≦ 0.3 μm. Comprising ultrasonic bonding in a state where the first metal member and the second metal member are in surface contact with each other,
In the first member, the arithmetic mean height Ra of the surface roughness at the joint surface in surface contact with the second member satisfies Ra ≦ 0.3 μm.   The method for manufacturing a power storage element according to claim 2, wherein the joint surface of the first member is made of aluminum or an aluminum alloy. The first member is an electrode body in which electrodes are laminated,
The method for manufacturing a power storage element according to claim 2 or 3, wherein the second member is at least one of a current collector and a contact plate disposed between the current collector and the electrode body.