JP6631866B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device including a power storage element.

  2. Description of the Related Art Conventionally, an assembled battery including a plurality of unit cells is known (for example, see Patent Document 1). Specifically, the battery pack includes a positive electrode terminal and a negative electrode terminal, and conducts a plurality of cells arranged in one direction (first direction) with the positive electrode terminal and the negative electrode terminal of the adjacent cell. A bus bar.

  Each of the plurality of unit cells includes a battery container accommodating a wound electrode group, and a positive electrode terminal and a negative electrode terminal attached to the battery container and electrically connected to the wound electrode group. Each of the positive electrode terminal and the negative electrode terminal is attached to one end of the battery container in a second direction orthogonal to a first direction. Each of the positive electrode terminal and the negative electrode terminal has a flat terminal surface facing the one in the second direction. The bus bar has a rectangular flat plate shape. The bus bar is welded to the positive electrode terminal and the negative electrode terminal in a state where one surface in a thickness direction (second direction) is in surface contact with each of the adjacent positive electrode terminal and the negative electrode terminal. . Thus, the bus bar conducts the positive terminal and the negative terminal.

  In the assembled battery, the terminal surface of the positive electrode terminal and the terminal surface of the negative electrode terminal of the adjacent unit cells may not be on the same plane due to a tolerance or an arrangement error of each part at the time of manufacture. In this case, if the bus bar is arranged so as to bridge over the positive terminal and the negative terminal for welding, for example, as shown in FIG. 20, the bus bar 50 has the respective terminal surfaces of the positive terminal 52 and the negative terminal 54. The posture becomes inclined with respect to 520 and 540, and one terminal (the negative terminal 54 in the example shown in FIG. 20) abuts on a corner (peripheral edge of the terminal surface 540). That is, the portion 502 of the bus bar 50 that connects the portions 501 that contact the respective terminal surfaces 520 and 540 hits one corner of the pole terminal 54, and the contact portion 501 cannot contact the terminal surface 540. If welded in this state, only the contact portion between the bus bar 50 and the one terminal 54 (peripheral edge of the terminal surface 540) and the portion adjacent to the contact portion on the terminal surface 540 side are joined, so that a sufficient joining area is provided. (That is, a sufficient welding area cannot be obtained in a state where a welding area is formed at a position including the periphery of the terminal surface 540), and as a result, sufficient welding strength may not be obtained.

  In addition, in order to secure a welding area between the terminal surfaces 520 and 540 and the bus bar 50, as shown in FIG. 21, the bus bar 50 is arranged so as to bridge the positive terminal 52 and the negative terminal 54. It is conceivable that the bus bar 50 and the positive terminal 52 or the negative terminal 54 are welded in this state by pressing the bus bar 50 and the terminal surfaces 520 and 540 with the jig 60 so as to be in close contact with each other. However, in this case, since the bus bar 50 deformed by the pressing tries to return to the original shape, stress (initial stress) remains in the bus bar 50 after welding, which affects the bus bar 50 and a welded portion (weld region). .

JP 2013-93160 A

  Therefore, an object of the present invention is to provide a power storage device in which welding strength between a bus bar and an external terminal is ensured and initial stress is less likely to be generated in the bus bar even when there is a tolerance or an arrangement error of components.

The power storage device according to the present invention,
External terminals, and a plurality of power storage elements having a case where the external terminal is disposed at one end of the first direction, a plurality of power storage elements arranged in a second direction orthogonal to the first direction,
A bus bar that makes external terminals of two of the plurality of power storage elements conductive,
Each of the two external terminals conducted by the bus bar has a terminal surface facing the one in a first direction,
The bus bar has a pair of joints each having a joint surface opposed to the terminal surface and welded to the terminal surface, and a joint that connects the pair of joints.
At least one of the terminal surface and the bonding surface facing each other is a convex surface that is convex toward the other side,
The power storage device, wherein a welding region between the terminal surface and the joining surface is formed inside a peripheral edge of the terminal surface when viewed in a first direction.

  According to such a configuration, at the time of welding the bus bar and the external terminal, the welding area is formed inside the periphery of the terminal surface (that is, the contact portion between the joining surface of the bus bar and the terminal surface of the external terminal and the corresponding portion). (A portion adjacent to the contact portion can be welded over the entire area around the contact portion.) Therefore, a sufficient welding region can be obtained as compared with a case where the welding region is formed at a position including the peripheral edge of the terminal surface. Thereby, sufficient welding strength can be obtained.

  Moreover, at least one of the terminal surface and the joining surface facing each other is a convex surface facing the mating side, and therefore, when welding the bus bar and the external terminal, the two external terminals (the bus bar may not be connected) due to a component tolerance or an arrangement error. Even if the respective terminal surfaces of the external terminals to be electrically connected are not on the same plane, the connection surface does not come into contact with a corner of the external terminal (the peripheral edge of the terminal surface) or the like, and the joint surface contacts the portion inside the peripheral edge of the terminal surface. Can be in contact. As a result, it is possible to perform welding to each external terminal while securing a sufficient welding area without deforming the bus bar, and as a result, generation of initial stress due to the tolerance and arrangement error during welding in the bus bar is reduced. Can be prevented.

In the power storage device,
The bonding surface may be the convex surface, and may have a shape in which a line of intersection of a virtual surface including a first direction and a second direction bulges toward the terminal surface.

  According to such a configuration, at the time of welding the bus bar and the external terminal, regardless of the amount of displacement in the first direction between the two terminal surfaces to which the bus bar is welded (the amount of displacement due to component tolerance and arrangement error). The contact area between the joining surface and the terminal surface in the second direction becomes substantially constant. Thereby, substantially constant welding strength can be obtained irrespective of the deviation amount.

in this case,
The joining surface may have a shape in which the shape of the line of intersection with the virtual surface at each position in a third direction orthogonal to the first direction and the second direction is the same.

  According to this configuration, since the shape of the intersection line at each position in the third direction is the same, the contact area between the joint surface and the terminal surface in the third direction is increased, thereby welding the bus bar to the external terminal. Strength is further improved.

In the power storage device,
The terminal surface is a plane,
The joining surface is the convex surface, and an intersection line between a first direction and a virtual surface including a third direction orthogonal to the first direction and the second direction swells toward the terminal surface. It may be a curve.

  According to this configuration, at the time of welding the bus bar and the external terminal, the amount of displacement (such as component tolerance and arrangement error) of the two terminal surfaces to which the bus bar is welded in the relative rotation direction about the second direction as the rotation center. ), The contact area between the joint surface and the terminal surface in the third direction is substantially constant. Thereby, substantially constant welding strength can be obtained irrespective of the deviation amount.

In the power storage device,
In the second direction,
One edge of the bus bar and the one edge of the joint surface at the joint on one side are at the same position,
The other edge of the bus bar and the other edge of the joint surface at the joint on the other side may be at the same position.

  According to such a configuration, the end of the bus bar in the second direction and the outer end of the joint surface (convex surface) are at the same position, that is, there is no portion protruding outside the joint surface (convex surface) in the second direction. Therefore, even if the two conductive terminal surfaces are greatly displaced from each other and the bus bar is greatly inclined with respect to the terminal surfaces, the projecting portions do not come into contact with the external terminals or the like, so that the joining surfaces and the terminal surfaces can be more reliably contacted. Can be in contact.

In the power storage device,
At least one of the pair of joints has a concave surface that is recessed toward the joint surface at a position opposite to the joint surface in the first direction,
The joining surface and the terminal surface may be welded by laser welding.

  According to this configuration, since the opposite surface in the first direction of the joining surface (convex surface) in the joining portion is concave, the thickness dimension in the first direction at the portion where the joining surface of the joining portion is provided is suppressed. And the heat capacity of such a portion is suppressed. Thereby, at the time of laser welding, by irradiating the laser into the concave surface, it is possible to preferably perform welding between the bus bar and the external terminal while suppressing the laser output and suppressing the thermal effect on other parts. .

In the power storage device,
The connection portion may be curved or bent so as to be convex toward the one of the first directions when viewed in a third direction orthogonal to the first direction and the second direction.

  According to this configuration, since the connection portion is curved or bent so as to project toward the one side in the first direction, two parts may be formed due to a component tolerance or an arrangement error during welding between the bus bar and the external terminal. When the respective terminal surfaces of the external terminals (external terminals to be conducted by the bus bar) are not on the same plane, the connecting portion is less likely to abut on the corners of the external terminals (peripheral edge of the terminal surface). Thereby, the joining surface can be more reliably brought into contact with a portion inside the peripheral edge of the terminal surface.

  As described above, according to the present invention, it is possible to provide a power storage device in which the welding strength between the bus bar and the external terminal is ensured and the initial stress is less likely to be generated in the bus bar even when there is a tolerance or an arrangement error of components.

FIG. 1 is a perspective view of a power storage device according to the present embodiment. FIG. 2 is an exploded perspective view of the power storage device. FIG. 3 is a perspective view of a power storage element used in the power storage device. FIG. 4 is an exploded perspective view of the power storage device. FIG. 5 is a perspective view of a bus bar used in the power storage device. FIG. 6 is a sectional view taken along the line VI-VI in FIG. FIG. 7 is a schematic diagram illustrating a state where external terminals of adjacent power storage elements are connected by the bus bar. FIG. 8 is a diagram for explaining a welded portion between the bus bar and an external terminal of the power storage element. FIG. 9 is a schematic diagram illustrating a state in which external terminals are connected to each other by the bus bar in a state where the relative positions of adjacent power storage elements are shifted. FIG. 10 is a schematic diagram showing a state in which external terminals having convex terminal surfaces are connected to each other by a plate-shaped bus bar. FIG. 11 is a schematic diagram showing a state in which external terminals having a convex terminal surface are connected to each other by a bus bar having a convex bonding surface. FIG. 12 is a diagram for explaining a bus bar having a joint surface curved along the XZ plane. FIG. 13 is a diagram for explaining a bus bar in which the joining surface is bent at a plurality of locations. FIG. 14 is a diagram for explaining a bus bar having the V-shaped joint surface. FIG. 15 is a diagram for explaining a bus bar in which the joining surface has a square shape. FIG. 16 is a diagram for explaining an external terminal having a concave terminal surface. FIG. 17 is a view for explaining a bus bar in which the joint does not have a concave surface. FIG. 18 is a view for explaining a bus bar having a portion extending outside the joint (convex surface). FIG. 19 is a diagram for explaining a bus bar that connects external terminals at distant positions. FIG. 20 is a diagram illustrating a conventional method for manufacturing a power storage device using a bus bar, and is a diagram illustrating a state where the bus bar is bridged between external terminals. FIG. 21 is a diagram illustrating a conventional method for manufacturing a power storage device using a bus bar, and is a diagram illustrating a state in which the bus bar is pressed against a terminal surface of an external terminal by a jig.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. It should be noted that the names of the components (components) in the present embodiment are those in the present embodiment, and may be different from the names of the components (components) in the background art.

  As shown in FIGS. 1 and 2, the power storage device includes a plurality of power storage elements 1 having external terminals 11 and arranged in one direction (aligned), and two of the plurality of power storage elements 1. A bus bar 5 for electrically connecting the external terminals 11 to each other. The power storage device of the present embodiment includes a plurality of bus bars 5. This power storage device includes a spacer 2 adjacent to the power storage element 1 and a holding member 3 that holds the power storage element 1 and the spacer 2 collectively. Since holding member 3 is formed of a conductive material such as metal, the power storage device includes insulator 4 having an insulating property between power storage element 1 and holding member 3.

  As shown in FIGS. 3 and 4, the power storage element 1 includes an electrode body 12 including a positive electrode and a negative electrode, a case 10 housing the electrode body 12, and a pair of external terminals (positive electrode) disposed on the outer surface of the case 10. Terminal and a negative electrode terminal) 11. In addition, power storage element 1 includes insulating member 14 for insulating case 10 and electrode body 12. The insulating member 14 of the present embodiment is formed by bending an insulating sheet into a bag.

  The electrode body 12 is a so-called wound-type electrode body formed by winding a positive electrode and a negative electrode while being insulated from each other. When lithium ions move between the positive electrode and the negative electrode in the electrode body 12, the electric storage element 1 is charged and discharged. The electrode body 12 may be a so-called stacked electrode body in which a plurality of leaf-shaped positive electrodes and a plurality of leaf-shaped negative electrodes are alternately laminated while being insulated from each other.

  The case 10 includes a case body 100 having an opening, and a cover plate 101 that closes the opening of the case body 100 and has a pair of external terminals 11 arranged on an outer surface.

  The case main body 100 includes a closing portion 100a (see FIG. 4) and a cylindrical body 100b connected to the periphery of the closing portion 100a so as to surround the closing portion 100a.

  The body 100b includes a pair of first walls 100c facing each other at an interval, and a pair of second walls 100d facing each other across the pair of first walls 100c. The interval between the pair of first walls 100c is smaller than the interval between the pair of second walls 100d. That is, the trunk 100b is a flat rectangular tube. One end of the trunk 100b is closed by the closing part 100a, and the other end of the trunk 100b is open. This opening is closed by the lid plate 101.

  In the following, for convenience, the direction (first direction) connecting closing portion 100a of power storage element 1 and cover plate 101 is referred to as the X-axis direction. In the orthogonal coordinate axes, one of the two axial directions (second direction) orthogonal to the X-axis direction and the direction in which the plurality of power storage elements 1 are arranged is referred to as the Y-axis direction, and the remaining one direction ( The third direction is referred to as a Z-axis direction. Accordingly, in each drawing, three orthogonal axes (coordinate axes) corresponding to the X-axis direction, the Y-axis direction, and the Z-axis direction are additionally illustrated.

  The external terminal 11 is a part that is electrically connected to the external terminal 11 of another power storage element 1 or an external device or the like. The external terminal 11 is arranged at one end of the case 10 in the X-axis direction (the cover plate 101 in the example of the present embodiment). The external terminal 11 is formed of a conductive member. For example, the external terminal 11 is formed of a metal material having high weldability, 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.

  The external terminal 11 has a terminal surface 110 to which the bus bar 5 is welded. The terminal surface 110 of the present embodiment is a plane facing one side (upward in FIG. 3) in the X-axis direction. The external terminal 11 of the present embodiment has a plate shape that extends along the lid plate 101. Specifically, the external terminal 11 has a rectangular plate shape that is long in the Z-axis direction when viewed in the X-axis direction. The external terminal 11 configured as described above is electrically connected to the electrode body 12 housed in the case 10 via the current collecting member 13 (see FIG. 4).

  As shown in FIGS. 5 to 7, the bus bar 5 includes a pair of joints 51 joined to the two external terminals 11 to be electrically connected, and a connection 52 connecting the pair of joints 51 to each other. The pair of joining portions 51 and the connecting portion 52 are formed integrally. The bus bar 5 of the present embodiment is configured by bending a plate material having a constant thickness that is rectangular when viewed in the X-axis direction so as to be W-shaped when viewed in the Z-axis direction. Specifically, it is as follows.

  The joint portion 51 has a joint surface 53 that faces the terminal surface 110 of the external terminal 11 and is welded to the terminal surface 110. This joint surface 53 is a convex surface that swells toward the terminal surface 110 of the external terminal 11.

  The joining surface (convex surface) 53 of the present embodiment is a curve (the joining surface in FIG. 6) in which the line of intersection with the XY surface (the surface including the X axis and the Y axis: a virtual surface) swells toward the terminal surface 110. (See the lower contour line of the portion 51). In addition, in the joining surface 53, the shape of the line of intersection with the XY plane at each position in the Z-axis direction is the same.

  The joining portion 51 has a concave surface 54 that is recessed toward the joining surface 53 at a position opposite to the joining surface 53 in the X-axis direction. The concave surface 54 of the present embodiment has a shape corresponding to the bonding surface 53, specifically, a surface shape parallel to the bonding surface 53. That is, the joint portion 51 of the present embodiment is a curved plate-shaped portion.

  The connection portion 52 is curved or bent so as to project toward the one side (upward in FIG. 6) in the X-axis direction when viewed in the Z-axis direction. The connecting portion 52 of the present embodiment is configured such that a central portion in the Y-axis direction is convex toward the one in the X-axis direction when viewed in the Z-axis direction, as viewed in the Z-axis direction. It is a curved shape.

  In the bus bar 5 as described above, the one edge of the bus bar 5 (the left side in FIG. 6) and the one edge of the joint surface 53 of the one joint portion 51 are located at the same position in the Y-axis direction. It is. In the Y-axis direction, the other edge of the bus bar 5 (on the right side in FIG. 6) and the other edge of the joining surface 53 of the joining portion 51 on the other side are at the same position.

  This bus bar 5 is laser-welded to the external terminal 11. Specifically, the bus bar 5 is welded by irradiating the laser to the concave surface 54 (see the arrow α in FIG. 7). At this time, the joint region between the terminal surface 110 and the joint surface 53 (the welded portion between the bus bar 5 and the external terminal 11) is formed inside the peripheral edge of the terminal surface 110 when viewed in the X-axis direction. In the present embodiment, for example, as shown in FIG. 8, the welded portion (joining region) 112 is formed to have an elliptical shape elongated in the Y-axis direction. At this time, in the region where the welded portion is formed, there is a portion where a gap is formed between the terminal surface 110 and the joint surface 53 before welding, but if the gap is smaller than about 80 μm, the welding strength is not significantly affected.

  The spacer 2 has an insulating property. As shown in FIG. 2, the spacer 2 of the present embodiment includes two types of spacers 2 (2A, 2B). Specifically, the power storage device includes a spacer (hereinafter, referred to as an internal spacer) 2 </ b> A disposed between two power storage elements 1 and a power storage element 1 adjacent to the end of the plurality of power storage elements 1 in the Y-axis direction. And a matching spacer (hereinafter referred to as an external spacer) 2B.

  The internal spacer 2A is adjacent to the power storage element 1 (specifically, the first wall 100c of the case main body 100) and extends along the power storage element 1, and a position of two power storage elements 1 adjacent to the base 20A. And a regulating portion 21A for preventing displacement.

  Base 20A is sandwiched between two power storage elements 1 in the Y-axis direction, and spreads in the XZ plane (a plane including the X-axis and the Z-axis). The base 20 </ b> A of the present embodiment forms a ventilation path through which a fluid (fluid for controlling the temperature of the power storage element 1: air in the example of the present embodiment) can flow (pass) between the adjacent power storage elements 1. . The base 20A of the present embodiment is formed such that the cross section in the XY plane direction has a rectangular wave shape.

  The regulating portion 21A regulates the movement of each of the storage elements 1 adjacent to the internal spacer 2A in the XZ plane direction with respect to the internal spacer 2A, so that the relative movement of the two storage elements 1 adjacent to each other with the internal spacer 2A interposed therebetween. Regulate. The restricting portions 21A extend from the base 20A toward the respective storage elements 1 adjacent to the base 20A.

  The internal spacers 2 </ b> A configured as described above are arranged between the adjacent power storage elements 1. That is, the power storage device includes a plurality of internal spacers 2A.

  The outer spacer 2B determines a base 20B adjacent to the power storage element 1 (specifically, the first wall 100c of the case main body 100) and extending along the power storage element 1, and a position of the power storage element 1 adjacent to the base 20B. And a regulating unit 21B. The base 20 </ b> B of the present embodiment is also adjacent to (opposes) a later-described terminal member 30 constituting the holding member 3. That is, external spacer 2 </ b> B is arranged between power storage element 1 and terminal member 30.

  The base 20B extends in the XZ plane direction. That is, the base 20B is formed in a plate shape.

  The base 20 </ b> B of the present embodiment forms a ventilation path through which the fluid can flow between the adjacent power storage elements 1. Specifically, the base 20B of the present embodiment extends from the surface of the base 20B facing the power storage element 1 toward the case 10 (the first wall 100c of the case body 100) of the power storage element 1 and extends in the Z-axis direction. It has a plurality of internal contacts that extend. Each of the plurality of internal contact portions is arranged at intervals in the X-axis direction. Thereby, a plurality of ventilation paths are formed between base 20B and power storage element 1.

  The restricting portion 21B restricts movement of the electric storage element 1 adjacent to the external spacer 2B in the XZ plane direction with respect to the external spacer 2B. Regulator 21B extends from base 20B toward power storage element 1 adjacent to base 20B.

  The external spacers 2B configured as described above are provided as a pair so as to sandwich the plurality of power storage elements 1 arranged in the Y-axis direction. That is, the power storage device includes a pair of external spacers 2B.

  As shown in FIGS. 1 and 2, the holding member 3 includes a pair of terminal members 30 arranged at positions adjacent to the external spacers 2 </ b> B, a frame 31 connecting the pair of terminal members 30, Is provided.

  The end member 30 extends along the base 20B of the outer spacer 2B. The end member 30 has a press contact portion 300 that contacts the base 20B of the external spacer 2B.

  The frame 31 extends in the Y-axis direction along the plurality of power storage elements 1 and connects the pair of terminal members 30 to each other. In the power storage device of the present embodiment, frames 31 are arranged on both sides in the Z-axis direction of a plurality of power storage elements 1 arranged in the Y-axis direction. That is, the holding member 3 of the present embodiment includes a pair of frames 31.

  According to the power storage device described above, when welding the bus bar 5 and the external terminal 11, the welding area (welded portion) 112 is formed inside the peripheral edge of the terminal surface 110 as shown in FIG. The contact portion between the joining surface 53 of the bus bar 5 and the terminal surface 110 of the external terminal 11 and the portion adjacent to the contact portion can be welded over the entire area around the contact portion. As compared with the case where the welding area is formed at the position including the above, the welding area is secured, and thereby sufficient welding strength can be obtained.

  In addition, since the joining surface 53 is a convex surface facing the mating side (terminal surface 110), when the bus bar 5 and the external terminal 11 are welded due to component tolerances and arrangement errors, as shown in FIG. Even if the respective terminal surfaces 110 of the external terminals 11 (the external terminals 11 to be electrically connected by the bus bar 5) are not on the same plane, the connection portions 52 are joined without contacting the corners of the external terminals 11 (peripheries of the terminal surfaces 110) and the like. The surface 53 can be brought into contact with a portion inside the peripheral edge of the terminal surface 110. Thereby, it is possible to perform welding to each of the external terminals 11 while securing a sufficient welding area without deforming the bus bar 5, and as a result, the initial stress due to the above-described tolerance and arrangement error at the time of welding in the bus bar 5 is obtained. Can be prevented from occurring.

  In the joint surface (convex surface) 53 of the present embodiment, the line of intersection with the XY plane is a curve that swells toward the terminal surface 110. Therefore, when the bus bar 5 and the external terminal 11 are welded, the amount of displacement between the two terminal surfaces 110 to which the bus bar 5 is to be welded in the X-axis direction (the amount of displacement due to component tolerances, placement errors, and the like: see FIG. 9). Regardless of), the length of the contact surface between the joint surface 53 and the terminal surface 110 in the Y-axis direction is substantially constant. Thereby, substantially constant welding strength can be obtained irrespective of the deviation amount.

  In the joint surface 53 of the present embodiment, the shape of the line of intersection with the XY plane at each position in the Z-axis direction is the same. For this reason, the contact area between the joint surface 53 and the terminal surface 110 in the Z-axis direction is increased, and the welding strength between the bus bar 5 and the external terminal 11 is further improved.

  In the power storage device of the present embodiment, the bus bar 5 has the concave surface 54 that is recessed toward the joint surface 53 at a portion of the joint portion 51 opposite to the joint surface 53, so that the joint surface 53 of the joint portion 51 is formed. The thickness dimension in the Z-axis direction at the portion where the is provided is suppressed, and the heat capacity of such a portion is suppressed. Thus, when laser welding is performed between the joint surface 53 and the terminal surface 110, the laser is irradiated into the concave surface 54, thereby suppressing the laser output and suppressing the thermal influence on other parts, and connecting the bus bar 5 and the outside. The welding with the terminal 11 is suitably performed.

  In the bus bar 5 of the present embodiment, the plate-shaped connecting portion 52 is curved so as to be convex toward one of the X-axis directions (upward in FIG. 7) when viewed in the Z-axis direction. For this reason, when the terminal surfaces 110 of the two external terminals 11 (the external terminals 11 conducted by the bus bar 5) are not on the same plane due to tolerances and arrangement errors of the parts when the bus bar 5 and the external terminals 11 are welded. In addition, it becomes more difficult for the connecting portion 52 to come into contact with the corner of the external terminal 11 (the peripheral edge of the terminal surface 110) (see FIG. 9). Thereby, the joining surface 53 can be more reliably brought into contact with the portion inside the peripheral edge of the terminal surface 110, and as a result, the welding area 112 where sufficient welding strength can be obtained can be reliably secured.

  In the bus bar 5 of the present embodiment, one end (the left end in FIG. 7) of the bus bar 5 and the one end of the joining surface (convex surface) 53 of the joining portion 51 on the one side in the Y-axis direction. The other end (the right end in FIG. 7) of the bus bar 5 and the other end of the joining surface (convex surface) 53 of the joining portion 51 on the other side are at the same position. For this reason, the bus bar 5 of the present embodiment does not have a portion that protrudes outside the joint surface (convex surface) 53 in the Y-axis direction. Accordingly, even if the two terminal surfaces 110 to be conducted are largely displaced from each other in the X-axis direction, for example, and the bus bar 5 is greatly inclined with respect to the terminal surfaces 110, the projecting portion does not come into contact with the external terminals 11 or the like. As a result, the joining surface 53 and the terminal surface 110 can be more reliably brought into contact with each other.

  It should be noted that the electric storage device of the present invention is not limited to the above embodiment, and it is needless to say that various changes can be made without departing from the spirit of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. Further, a part of the configuration of an embodiment can be deleted.

  In the power storage device of the above embodiment, the terminal surface 110 of the external terminal 11 is a flat surface and the joint surface 53 of the bus bar 5 is a convex surface, but the present invention is not limited to this configuration. For example, as shown in FIG. 10, the terminal surface 110 of the external terminal 110 may be a convex surface, and the joint surface 53 of the bus bar 5 may be a flat surface. In addition, as shown in FIG. 11, the terminal surface 110 of the external terminal 11 and the joint surface 53 of the bus bar 5 may be convex surfaces. That is, at least one of the terminal surface 110 and the bonding surface 53 facing each other may be a convex surface that is convex toward the other side.

  When the terminal surface 110 is a convex surface, the terminal surface 110 may be a curve in which the line of intersection with the XY plane swells toward the bonding surface 53. Further, the terminal surface 110 may have a shape in which the shape of the line of intersection with the XY plane at each position in the Z-axis direction is the same. Further, the terminal surface 110 may have a shape or the like in which a line of intersection with the XZ plane (virtual plane) bulges toward the bonding surface 53.

  The specific shape of the joint surface 53 of the bus bar 5 is not limited. That is, the joining surface 53 of the above embodiment is a curve in which the line of intersection with the XY plane swells toward the terminal surface 110, and the line of intersection with the XY plane at each position in the Z-axis direction. Although the shapes are the same, other shapes may be used. For example, as shown in FIG. 12, the joining surface 53 may have a shape in which a line of intersection with the XZ plane (virtual plane) bulges toward the terminal surface 110.

  According to such a configuration, when the bus bar 5 and the external terminal 11 are welded, regardless of the amount of displacement of the two terminal surfaces 110 to which the bus bar 5 is welded in the relative rotation direction about the Y-axis direction as the rotation center. The contact area between the joint surface 53 and the terminal surface 110 in the Z-axis direction becomes substantially constant. Thereby, substantially constant welding strength can be obtained irrespective of the deviation amount. Further, the joining surface 53 may have a shape in which an intersection line with the XY plane or the XZ plane is bent at two or more places, a V-shape or the like (see FIGS. 13 to 15).

  Further, the specific shape of the terminal surface 110 of the external terminal 11 is not limited. The terminal surface 110 is a curve in which the line of intersection with the XY surface swells toward the bonding surface 53, as in the bonding surface 53 of the above embodiment, and the XY surface at each position in the Z-axis direction. May be the same as the shape of the intersection line, or the shape of the intersection line with the XZ plane (virtual surface) may be a curve bulging toward the joint surface 53. Further, the terminal surface 110 may have a shape (polygonal shape) in which the line of intersection with the XY plane or the XZ plane is bent at two or more places.

  The terminal surface 110 of the external terminal 11 of the above embodiment is a flat surface, but is not limited to this configuration. For example, the terminal surface 110 may be a concave curved surface as shown in FIG. In this case, if the joint surface 53 is a convex surface or the like having a curvature larger than the curvature of the terminal surface 110, even if the relative attitude of the two external terminals 11 connected by the bus bar 5 is different due to an arrangement error or the like, an initial stress is generated. The bus bar 5 can be laser-welded to the external terminal 11 without causing the bus bar 5 to be welded.

  In addition, the specific shape of the surface opposite to the bonding surface 53 in the X-axis direction in the bonding portion 51 is not limited. For example, the bus bar 5 of the above embodiment has a concave surface 54 having a shape (corresponding to, for example, parallel) to the bonding surface (convex surface) 53 at the bonding portion 51, but is not limited to this configuration. The concave surface 54 does not need to have a shape corresponding to the joint surface (convex surface) 53 as long as the bus bar 5 can be welded to the external terminal 11 by irradiating a laser into the concave surface 54. Further, the bus bar 5 may have a configuration in which both the joints 51 do not have the concave surface 54 as shown in FIG. 17, or may have a configuration in which only one of the joints 51 has the concave surface 54. In these cases, laser welding is performed on the joint 51 without the concave surface 54 by irradiating a laser from around the joint surface (convex surface) 53.

  The connecting portion 52 of the above embodiment is curved or bent so as to be convex toward one of the X-axis directions when viewed in the Z-axis direction, but is not limited to this configuration. The connecting portion 52 may extend substantially straight in the Y-axis direction, for example (see FIG. 17). Further, the width of the connecting portion 52 in the Z-axis direction may not be the same as the width of the joining portion 51 in the Z-axis direction.

  The thickness of each part of the bus bar 5 of the above embodiment is constant or substantially constant (that is, a plate-like member), but is not limited to this configuration. The thickness at each part of the bus bar may not be constant.

  In the bus bar 5 of the above embodiment, the end of the joining surface (convex surface) 53 and the end of the bus bar 5 are at the same position in the Y-axis direction, but the present invention is not limited to this configuration. For example, as shown in FIG. 18, in the bus bar 5, there may be a portion 55 that further extends in the Y-axis direction from the end of the joining surface (convex surface) 53. In this case, if the two electric storage elements 1 conducted by the bus bar 5 are largely displaced in the X-axis direction, the portion 55 is likely to abut on other members such as the spacer and the other electric storage elements 1, so that the extension amount is increased. (The dimension of the extending portion 55 in the Y-axis direction) is preferably as small as possible.

  Although the bus bar 5 of the above embodiment connects the external terminals 11 of the adjacent power storage elements 1, it is not limited to this configuration. For example, as shown in FIG. 19, the bus bar 5 has external terminals 11 of two (one pair) of power storage elements 1 sandwiching one or more (two in the example of FIG. 19) power storage elements 1 in the Y-axis direction. They may be connected to each other.

  DESCRIPTION OF SYMBOLS 1 ... Electric storage element, 10 ... Case, 100 ... Case main body, 100a ... Closed part, 100b ... Body part, 100c ... First wall, 100d ... Second wall, 101 ... Cover plate, 2 ... Spacer, 2A ... Internal spacer, 20A: base, 21A: regulating portion, 2B: external spacer, 20B: base, 21B: regulating portion, 3: holding member, 30: terminating member, 31: frame, 4: insulator, 5: bus bar, 51: joining portion, 52 connecting part, 53 joining surface, 54 concave surface, 55 further extending part, 11 external terminal, 110 terminal surface, 112 welding part (welding region), 12 electrode body, 13 current collecting member, 14 ... Insulating member

Claims (7)

An external terminal having conductivity , and a plurality of power storage elements having a case in which the external terminal is disposed at one end in a first direction, wherein the plurality of power storage elements are arranged in a second direction orthogonal to the first direction. When,
A bus bar for conducting the external terminals having conductivity of two of the plurality of power storage elements,
Each of the two external terminals having conductivity that is conducted by the bus bar has a terminal surface that faces the one side in a first direction,
The bus bar has a pair of joints each having a joint surface opposed to the terminal surface and welded to the terminal surface, and a joint connecting the pair of joints.
At least one of the terminal surface and the bonding surface facing each other is a convex surface that is convex toward the other side,
A welding area between the terminal surface and the joining surface is formed inside a peripheral edge of the terminal surface when viewed in the first direction,
The power storage device, wherein the external terminal having conductivity has a rectangular plate shape that is long in a third direction orthogonal to the first direction and the second direction when viewed in the first direction.   2. The joint surface according to claim 1, wherein the joint surface is the convex surface, and has a shape in which a line of intersection of a virtual surface including a first direction and a second direction bulges toward the terminal surface. 3. Power storage device.   3. The power storage device according to claim 2, wherein the joining surface has a shape in which a shape of an intersecting line with the virtual surface at each position in a third direction orthogonal to the first direction and the second direction is the same. 4.   The joining surface is the convex surface, and an intersection line between a first direction and a virtual surface including a third direction orthogonal to the first direction and the second direction swells toward the terminal surface. The power storage device according to claim 1, wherein the power storage device is a curve. In the second direction,
One edge of the bus bar and the one edge of the joint surface at the joint on one side are at the same position,
The power storage device according to any one of claims 2 to 4, wherein the other edge of the bus bar and the other edge of the joint surface at the joint on the other side are at the same position. At least one of the pair of joints has a concave surface that is recessed toward the joint surface at a position opposite to the joint surface in the first direction,
The power storage device according to claim 1, wherein the joining surface and the terminal surface are welded by laser welding.   The connection portion according to any one of claims 1 to 6, wherein the connection portion is curved or bent so as to be convex toward the one of the first directions in a third direction orthogonal to the first direction and the second direction. 2. The power storage device according to claim 1.

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