JP7205068B2 - power storage device - Google Patents

Description

The present invention relates to a power storage device with busbars.

2. Description of the Related Art Conventionally, a power storage device is known that includes a plurality of power storage elements housed in an exterior body and bus bars that electrically connect the plurality of power storage elements within the exterior body. The busbar is welded to the welding surface of the electrode terminal of the storage element. Here, the bus bar is provided with an opening for measurement, for example, in order to measure the height of the electrode terminal after welding (see, for example, Patent Document 1).

WO2016/035334

By the way, the electrode terminal of the storage element may be provided with a protruding portion that protrudes from the welding surface. In order to prevent interference with the projecting portion, it is assumed that the bus bar that is joined to such an electrode terminal is formed with a through hole into which the projecting portion is inserted. However, if an opening for measurement and a through hole are formed in the busbar, the area of the opening with respect to the busbar increases, and the strength of the busbar itself may decrease.

Therefore, an object of the present invention is to provide a power storage device capable of suppressing a decrease in strength of a busbar that achieves suppression of interference with the projections of electrode terminals and securement of space for measurement.

To achieve the above object, a power storage device according to one aspect of the present invention includes an exterior body, a plurality of energy storage elements housed in the exterior body, and a bus bar connecting electrode terminals of the energy storage elements. has a welded surface to which the busbar is welded and a protruding portion protruding from the welded surface, the busbar has a through hole into which the protruding portion is inserted, and the periphery of the through hole There is a first portion that follows and a second portion that does not.

According to this, the peripheral portion of the through hole is provided with a first portion along the outer periphery of the protrusion and a second portion not along the outer periphery. The first portion is also a portion to be welded with the electrode terminal, and the electrode terminal exposed from the first portion is not flattened by welding. On the other hand, since the second portion is also a portion that is not welded to the electrode terminal, the electrode terminal exposed from the second portion remains flat. The height of the electrode terminal can be measured by irradiating the electrode terminal exposed from the second portion with a laser from, for example, a laser displacement meter. That is, since the through-hole has a portion into which the protruding portion is inserted and a portion for measuring the height of the electrode terminal are integrally formed, the through-hole is even better than when these are separate bodies. , the total opening area in the busbar can be reduced. Therefore, the reduction in strength of the busbar itself can be suppressed. As a result, it is possible to suppress a decrease in the strength of the busbar that achieves suppression of interference with the projecting portion of the electrode terminal and securing of space for measurement.

Also, the second portion is a recess that is recessed outward with respect to the first portion.

According to this, the size of the second portion can be made compact by making the second portion the concave portion. Thereby, the total opening area in the busbar can be made smaller. Therefore, it is possible to suppress a decrease in the strength of the busbar itself and to further suppress an increase in electrical resistance.

Also, two recesses are provided in the peripheral portion of the through hole.

According to this, if there is only one concave portion in the peripheral portion of the through hole, the projecting portion of the electrode terminal may be shifted toward the concave portion during assembly, and the concave portion may be narrowed. However, if there are two recesses, even if the protruding part approaches one of the recesses during assembly, the other recess is less likely to narrow. Therefore, it is possible to secure a space for measuring the height of the electrode terminals.

Also, the two recesses are arranged along the direction of current flow in the bus bar.

According to this, since the two recesses are arranged along the direction of current flow in the busbar, the cross-sectional area of the busbar in the plane perpendicular to the flow direction is not narrowed by the recesses. As a result, an increase in electrical resistance caused by the concave portion can be suppressed.

Also, the two recesses are arranged along the flow direction, so that they are arranged at positions facing each other with the center of the through hole interposed therebetween. In other words, even if the protruding portion moves toward one of the recessed portions during assembly, the other recessed portion will not be narrowed. Therefore, a space for measuring the height of the electrode terminal can be reliably secured.

Moreover, the bus bar has a plurality of through holes, and the second portions of the plurality of through holes are arranged on the same straight line.

According to this, since the second portions of the plurality of through-holes are arranged on the same straight line, for example, by linearly scanning the laser from the laser displacement gauge, the corresponding through-holes can be detected. The height of the electrode terminals can be easily measured.

According to the power storage device of the present invention, it is possible to suppress a decrease in strength and an increase in electrical resistance in the bus bar that achieves suppression of interference with the projecting portion of the electrode terminal and securing of space for measurement.

FIG. 1 is a perspective view showing the appearance of a power storage device according to an embodiment. FIG. 2 is an exploded perspective view showing each component when the power storage device according to the embodiment is exploded. FIG. 3 is a perspective view showing a part of the power storage element and the bus bar according to the embodiment. FIG. 4 is an exploded perspective view showing a part of the power storage element and the bus bar according to the embodiment. FIG. 5 is a top view showing a part of the storage element and the bus bar according to the embodiment. FIG. 6 is a top view showing a busbar according to Modification 1. FIG. FIG. 7 is a top view showing a busbar according to Modification 2. FIG.

Hereinafter, power storage devices according to embodiments and modifications thereof of the present invention will be described with reference to the drawings. It should be noted that the embodiments and modifications thereof described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments and modifications thereof are examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments and modifications thereof, constituent elements that are not described in independent claims representing the highest level concept will be described as optional constituent elements. Also, in each drawing, dimensions and the like are not strictly illustrated.

In the following description and drawings, the direction in which the energy storage elements are arranged, the direction in which the energy storage elements are opposed to the long sides of the container, or the thickness direction of the container is defined as the X-axis direction. In addition, the direction in which the electrode terminals of one storage element are arranged or the direction in which the short sides of the container of the storage element face each other is defined as the Y-axis direction. In addition, the direction in which the main body and the outer lid are arranged in the exterior body of the power storage device, the direction in which the power storage elements, the bus bar and the substrate are arranged, or the vertical direction is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect each other (in the following embodiments and modifications thereof, they are orthogonal). Although the Z-axis direction may not be the vertical direction depending on the mode of use, the Z-axis direction will be described below for convenience of explanation. Further, in the following description, for example, the X-axis direction plus side indicates the arrow direction side of the X-axis, and the X-axis direction minus side indicates the side opposite to the X-axis direction plus side. The same applies to the Y-axis direction and the Z-axis direction.

[General description of power storage device]
First, a general description of a power storage device 1 according to an embodiment will be given with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective view showing the appearance of a power storage device 1 according to an embodiment. FIG. 2 is an exploded perspective view showing each component when the power storage device 1 according to the embodiment is exploded.

The power storage device 1 is a device capable of charging electricity from the outside and discharging electricity to the outside. For example, the power storage device 1 is a battery module used for power storage or power supply. Specifically, the power storage device 1 is, for example, an electric vehicle (EV), a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV) such as an automobile, a motorcycle, a watercraft, a snowmobile, an agricultural machine, a construction It is used as a battery for driving a moving object such as a machine or for starting an engine.

As shown in FIGS. 1 and 2 , the power storage device 1 includes a power storage element 20 and an exterior body 10 that accommodates the power storage element 20 . In the present embodiment, exterior body 10 accommodates eight power storage elements 20 . The exterior body 10 has a main body portion 12 that accommodates the plurality of power storage elements 20 and a busbar plate 17 that is arranged above the plurality of power storage elements 20 . In the present embodiment, exterior body 10 further includes outer lid 11 arranged to cover upper side of bus bar plate 17 . Inside the exterior body 10, in addition to the plurality of power storage elements 20, a plurality of busbars 33 held by the busbar plate 17, busbar covers 60 and 70, and a connection unit 80 including a control circuit and the like are accommodated. .

The exterior body 10 is a rectangular (box-shaped) container (module case) that constitutes the exterior body of the power storage device 1 . In other words, the exterior body 10 is a member that fixes the plurality of power storage elements 20, the bus bar plate 17, and the like at predetermined positions and protects these elements from impacts and the like.

The outer cover 11 of the exterior body 10 is a rectangular member that closes the opening of the main body 12 and has a positive electrode side external terminal 91 and a negative electrode side external terminal 92 . The external terminals 91 and 92 are electrically connected to the plurality of power storage elements 20 via the connection unit 80 and the bus bar 33, and the power storage device 1 receives electricity from the outside via the external terminals 91 and 92. Charges and discharges electricity to the outside. The external terminals 91 and 92 are made of, for example, a metal conductive member such as a copper alloy such as brass, copper, aluminum, or an aluminum alloy. The main body 12 is a bottomed rectangular cylindrical housing (casing) having an opening, and accommodates the power storage element 20 and the like.

Further, the main body 12 and the outer lid 11 of the exterior body 10 are made of, for example, polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyphenylene sulfide resin (PPS), polyetheretherketone (PEEK), tetrafluoroethylene.・Composed of insulating materials such as perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), modified polyphenylene ether (m-PPE) or poly ether sulfone (PES) . The exterior body 10 thereby avoids contact of the power storage element 20 and the like with an external metal member or the like.

The storage element 20 is a secondary battery (single battery) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. . The storage element 20 has a flat rectangular parallelepiped (rectangular) shape, and in the present embodiment, eight storage elements 20 are arranged in the X-axis direction. In addition, the shape of the electric storage element 20 and the number of the electric storage elements 20 arranged are not limited. Moreover, the storage element 20 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. It may be a primary battery that can use the stored electricity without using the battery. Furthermore, the storage element 20 may be a battery using a solid electrolyte. Moreover, the shape of the electric storage element 20 is not limited to a rectangular shape, and may be a columnar shape, an oval columnar shape, or a polygonal columnar shape other than a rectangular parallelepiped.

Specifically, the power storage element 20 includes a metal container 21 , and a lid portion of the container 21 is provided with a positive electrode terminal 221 and a negative electrode terminal 222 made of metal. An insulating member 23 (see FIG. 4) is interposed between the lid portion and the positive electrode terminal 221 and the negative electrode terminal 222. The insulating member 23 insulates the lid portion from the positive electrode terminal 221 and the negative electrode terminal 222. .

The positive terminal 221 and the negative terminal 222 are electrode terminals that protrude from the cover portion of the container 21 toward the busbar plate 17 (upward, that is, toward the positive side in the Z-axis direction). By connecting the positive terminal 221 and the negative terminal 222 to the external terminals 91 and 92 via at least one bus bar 33 and the connection unit 80, the power storage device 1 is charged with electricity from the outside and is supplied to the outside. Can discharge electricity. Note that the lid portion of the container 21 may be provided with an injection portion for injecting the electrolytic solution, a gas discharge valve for releasing the pressure by discharging gas when the pressure inside the container 21 rises, and the like. In addition, an electrode body (also referred to as a storage element or a power generation element), a current collector (a positive electrode current collector and a negative electrode current collector), and the like are arranged inside the container 21, and an electrolytic solution (non-aqueous electrolyte) and the like are arranged. Although enclosed, detailed description is omitted.

The bus bar 33 is arranged on at least two storage elements 20 while being held by the bus bar plate 17, and has a rectangular shape that electrically connects the positive terminal 221 and the negative terminal 222 of the at least two storage elements 20 to each other. It is a plate-shaped member. The busbar 33 is made of a conductive member made of metal such as copper, copper alloy, aluminum, aluminum alloy, or the like. In the present embodiment, five bus bars 33 are used to connect two power storage elements 20 in parallel to form four power storage element groups, and the four power storage element groups are connected in series. Connected. In the present embodiment, of the five bus bars 33 , two bus bars 331 located at both ends in the series direction are joined to two storage elements 20 , and the other three bus bars 332 are joined to four storage elements 20 . is joined to The two busbars 331 are the same part. Also, the three bus bars 332 are the same component.

Also, the connection unit 80 is a unit having a plurality of bus bars, a control board, etc., and connects a power storage element group including eight power storage elements 20 to the external terminals 91 and 92 . The control board of the connection unit 80 has a plurality of electrical components, and these electrical components form a detection circuit for detecting the state of each storage element 20, a control circuit for controlling charging and discharging, and the like. there is In this embodiment, connection unit 80 is fixed to busbar plate 17 . Note that the detection circuit and the control circuit may be formed on separate substrates. Also, the connection unit 80 may not have a control board. In this case, for example, a control device arranged outside the power storage device 1 may control charging and discharging of each power storage element 20 .

The busbar plate 17 is an example of a holding member arranged above the plurality of power storage elements 20 (the side on which the positive electrode terminal 221 and the negative electrode terminal 222 are arranged). is. More specifically, the busbar plate 17 is a member that holds a plurality of busbars 33, connection units 80, and other wirings (not shown) and can regulate the positions of these members. Further, the busbar plate 17 is provided with a plurality of busbar openings 17a that hold the plurality of busbars 33 and expose a portion of each of the plurality of busbars 33 toward the plurality of power storage elements 20 . . In addition, the busbar plate 17 is fixed to the main body 12 by a method described later, and has a role of, for example, restricting upward movement (toward the positive side in the Z-axis direction) of the plurality of power storage elements 20 .

The busbar plate 17 arranged above the plurality of power storage elements 20 may be called, for example, a "busbar frame" or an "inner cover". Also, the busbar plate 17 is made of an insulating material such as PP, PE, PC, PPS, PEEK, PFA, PTFE, PBT, m-PPE, or PES.

Each of the busbar covers 60 and 70 is a resin member that covers the plurality of busbars 33 from above, and serves, for example, to electrically insulate the plurality of busbars 33 and the connection unit 80 .

[Joint structure between power storage element and bus bar]
Next, the joint structure between the storage element 20 and the bus bar 332 will be specifically described. FIG. 3 is a perspective view showing a portion of power storage element 20 and bus bar 332 according to the embodiment. FIG. 4 is an exploded perspective view showing part of power storage element 20 and bus bar 332 according to the embodiment. FIG. 5 is a top view showing part of power storage element 20 and bus bar 332 according to the embodiment. 3 to 5 show four power storage elements 20 among the eight power storage elements 20 provided in the power storage device 1 and one bus bar 332 joined to these power storage elements 20. FIG. Although the bus bar 331 will not be described in detail, it is assumed that the same joint structure is adopted for the electric storage element 20 .

First, the positive terminal 221 and the negative terminal 222 of the storage element 20 will be described. The positive terminal 221 and the negative terminal 222 are made of aluminum, an aluminum alloy, or the like.

Positive electrode terminal 221 has a flat top surface, and bus bar 332 is welded to the top surface. That is, the top surface of the positive electrode terminal 221 is the welding surface 221a.

The negative electrode terminal 222 is electrically connected to the negative electrode current collector accommodated in the container 21 . Here, since the negative electrode current collector is made of a material different from that of the negative electrode terminal 222 (for example, copper or a copper alloy), the negative electrode terminal 222 and the negative electrode current collector are made of copper or a copper alloy. Connected via rivets. The rivet is a member for connecting the negative terminal 222 and the negative current collector and for attaching (fixing) the negative terminal 222 and the negative current collector to the lid of the container 21 . As a result, the tip of the rivet protrudes from the top surface of the negative terminal 222 . A top surface of negative terminal 222 is formed in a flat shape, and bus bar 332 is welded to the top surface. In other words, the top surface of the negative electrode terminal 222 is the welding surface 222 a , and the rivet projecting from the welding surface 222 a is the projecting portion 223 . The protruding portion 223 has a circular shape in plan view (viewed in the Z-axis direction).

Next, bus bar 332 will be described. The bus bar 332 is a member made of sheet metal elongated along the direction in which the plurality of power storage elements 20 are arranged (the X-axis direction). Specifically, the bus bar 332 includes a plurality of flat plate portions 31 and curved portions 32 provided between the plurality of flat plate portions 31 .

For example, four flat plate portions 31 are provided in the present embodiment, and are arranged along the X-axis direction. The plurality of flat plate portions 31 are joined to the positive terminal 221 or the negative terminal 222 of each different storage element 20 .

A through hole 335 is provided in the substantially central portion of the flat plate portion 31 in plan view (viewed in the Z-axis direction). All of the through holes 335 provided in each of the plurality of flat plate portions 31 are arranged along a straight line (virtual straight line L1 in FIG. 5) parallel to the X-axis direction. Two arcuate portions 336 and two rectangular recesses 337 that are recessed outward from the arcuate portion 336 are provided in the peripheral portion of the through hole 335 . The two arcuate portions 336 are arranged on the same circumference, and the diameter of the circumference is larger than the outer diameter of the projecting portion 223 of the negative terminal 222 .

The recess 337 forms an opening for measuring the height of the positive electrode terminal 221 or the negative electrode terminal 222 . Specifically, the height of the top surface (welding surfaces 221a and 222a) of the positive electrode terminal 221 or the negative electrode terminal 222 exposed from the recess 337 is measured by inserting a height measuring laser or a needle into the recess 337. can be detected. The height measurement method will be described later.

The two recesses 337 are arranged at positions facing each other across the center of the through hole 335 . Specifically, the two recesses 337 are arranged along a straight line (imaginary straight line L1 in FIG. 5) passing through the center of the through-hole 335 in the Y-axis direction and parallel to the X-axis direction. Moreover, the concave direction of the two concave portions 337 is also along the imaginary straight line L1. The recessed portion 337 is formed to have a size that allows insertion of at least a height measuring laser or meter reading. However, if the concave portion 337 becomes too large, the strength of the bus bar 332 itself will be greatly reduced. For this reason, the concave portion 337 is not made as large as possible, but is slightly larger than the diameter of the height measuring laser or needle detector. Specifically, the diameter (or width) D of the concave portion 337 may satisfy d<D<1.1d, where d is the diameter of the height measurement laser or meter reading. For example, since the diameter of a laser for height measurement is generally about 3 mm, the diameter (or width) of the recess 337 should be greater than 3 mm and less than 3.3 mm.

The curved portion 32 is curved in a shape that protrudes upward (the positive side in the Z-axis direction). With such a shape, the curved portion 32 absorbs impact and thermal deformation on the bus bar 332 .

Next, a joint structure between the storage element 20 and the bus bar 332 will be described. The bus bar 332 is welded to the positive terminal 221 or the negative terminal 222 of each storage element 20 . For example, positive terminals 221 of different storage elements 20 are welded to two flat plate portions 31 on the negative side of the bus bar 332 in the X-axis direction. Negative terminals 222 of different storage elements 20 are welded to the two flat plate portions 31 on the positive side of the bus bar 332 in the X-axis direction.

Specifically, before welding, bus bar 332 is aligned with positive electrode terminal 221 or negative electrode terminal 222 of each storage element 20 . At this time, the projecting portion 223 of the negative electrode terminal 222 is inserted into the through hole 335 of the flat plate portion 31 corresponding to the negative electrode terminal 222 . After alignment, a gap S is formed between the arcuate portion 336 of the through hole 335 and the projecting portion 223 in each flat plate portion 31 . Through this gap S, the circular arc portion 336 of each flat plate portion 31 is welded to the welding surface 221a of the positive electrode terminal 221 or the welding surface 222a of the negative electrode terminal 222, for example, by laser welding. Therefore, the welding surface 222a exposed from the gap S is not flattened by welding. On the other hand, the welding surface 222a in the recess 337 is kept flat because it is not welded.

Also, the projecting portion 223 of the negative electrode terminal 222 is not welded to the flat plate portion 31 . For example, if the protrusion 223 is fitted in the through hole 335 and the boundary portion between the protrusion 223 and the through hole 335 is welded, the flat plate portion 31 may be lifted from the welding surface 222a. In the present embodiment, the flat plate portion 31 is directly welded to the welding surface 222a, so it is possible to prevent the flat plate portion 31 from floating from the welding surface 222a.

In addition, as described above, since the concave portion 337 is not formed so large from the viewpoint of securing strength, there is a possibility that the concave portion 337 may be crushed by the heat of welding. For example, when welding the boundary portion between the protrusion 223 and the through-hole 335 with the protrusion 223 fitted in the through-hole 335, heat is transferred to the welding surface 222a to weld the welding surface 222a. , and a large amount of heat is transferred to the concave portion 337 accordingly. This heat may deform or melt the concave portion 337 and cause it to collapse. The crushing of the concave portion 337 is one of the factors that hinder the accuracy of height measurement.

On the other hand, in the present embodiment, arc-shaped portion 336 of through-hole 335 in flat plate portion 31 and welding surface 222a of negative electrode terminal 222 are directly welded. Also, the heat transmitted to the concave portion 337 can be reduced. Therefore, it is possible to make the concave portion 337 less likely to be crushed.

After welding, the through-hole 335 into which the projecting portion 223 is inserted is provided with a first portion along the outer periphery of the projecting portion 223 and a second portion not along the outer periphery. Here, "the first portion along the outer circumference of the protruding portion 223" refers to a portion facing a part of the outer circumference of the protruding part 223 and having an outer shape similar to the part. Approximation includes congruence and similarity. Also, the “second portion not along the outer periphery of the protruding portion 223” refers to a portion that faces a portion of the protruding portion 223 but has an outer shape that does not resemble the portion. Furthermore, the second portion has a shape that is more distant from the projecting portion 223 than the first portion. In the case of this embodiment, the first portion is arcuate portion 336 and the second portion is recess 337 .

After welding, the direction of current flow in bus bar 332 is the X-axis direction. Thereby, the two recesses 337 provided in each through-hole 335 are arranged along the current flow direction. Thus, in each through-hole 335 , two recesses 337 are arranged along the direction of current flow in the busbar 332 , so that the cross-sectional area of the busbar 332 in the plane perpendicular to the flow direction is determined by the recesses 337 . not narrowed. Thereby, an increase in electrical resistance caused by the concave portion 337 can be suppressed.

Although not shown, the welding area in the welded portion can be preferably carried out in a range not positioned on the imaginary straight line L1 and recessed portion 337 in FIG. For example, in the flat plate portion 31, the welding region is provided with a start point and an end point of welding separated from the concave portion 337 (virtual straight line L1) by a predetermined distance in the Y-axis direction, and is formed in an arc shape on the XY plane along the arc portion 336. It is possible to In addition, if the welding region is provided with a start point and an end point of welding at a predetermined distance from each recess 337, it is possible to form a welding trajectory linearly in the X-axis direction, for example, in the flat plate portion 31. be.

[Height measurement method]
During assembly or maintenance of the power storage device 1, the heights of the positive terminal 221 and the negative terminal 222 of each power storage element 20 may be measured. Here, the height measurement method will be described.

A laser displacement meter, for example, is used to measure the height of the positive electrode terminal 221 and the negative electrode terminal 222 . Since the laser displacement gauge irradiates the laser so as to scan the imaginary straight line L1, the laser scans the inside of each through hole 335 of the bus bar 332 . Thereby, the heights of the plurality of electrode terminals (the two positive terminals 221 and the two negative terminals 222) joined to the bus bar 332 can be measured in one scan.

Specifically, on the welding surfaces 221a and 222a of the positive electrode terminal 221 and the negative electrode terminal 222, the portion exposed from the through hole 335 on the positive electrode terminal 221 imaginary straight line L1 is to be measured. Since the welding surface 221a of the positive electrode terminal 221 is exposed from the entire through-hole 335, the height is measured over a wide range by laser. On the other hand, the welding surface 221a of the negative electrode terminal 222 is to be measured within the concave portion 337 . In either case, the object to be measured remains flat because there is no weld on the imaginary straight line L1. Therefore, it is possible to accurately measure the height of each of the positive electrode terminal 221 and the negative electrode terminal 222 .

Here, the bus bar 332 may be displaced to one side in the X-axis direction. In this case, in the negative electrode terminal 222, of the two recesses 337 provided in one through-hole 335, one of the recesses 337 is narrowed because it is close to the projecting portion 223, but the other recess 337 is not narrowed. Absent. That is, one recess 337 of the two recesses 337 reliably secures the space required for measurement. Therefore, even if the bus bar 332 is displaced in the X-axis direction, the height of each negative terminal 222 can be reliably measured.

It should be noted that it is also possible to use a displacement meter having a probe that can be inserted into the concave portion 337 of the busbar 332 for height measurement.

[Effects, etc.]
As described above, according to the power storage device 1 according to the present embodiment, the exterior body 10, the plurality of energy storage elements 20 housed in the exterior body 10, and the electrode terminals (negative terminals 222) of the energy storage elements 20 are connected. The electrode terminal has a welding surface 222a to which the busbar 332 is welded and a projecting portion 223 projecting from the welding surface 222a. The busbar 332 has a through hole 335 into which the projecting portion 223 is inserted. A peripheral portion of the through-hole 335 is provided with a first portion (an arc-shaped portion 336) that follows the outer periphery of the protruding portion 223 and a second portion (a recessed portion 337) that does not follow the outer periphery.

According to this, the peripheral portion of the through-hole 335 is provided with an arcuate portion 336 that follows the outer periphery of the projecting portion 223 and a recessed portion 337 that does not follow the outer periphery. The arcuate portion 336 is also a portion to be welded to the negative electrode terminal 222, and the welding surface 222a of the negative electrode terminal 222 exposed from the first portion is not flattened by welding. On the other hand, since the concave portion 337 is also a portion that is not welded to the negative electrode terminal 222, the welding surface 222a of the negative electrode terminal 222 exposed from the concave portion 337 maintains a flat state. The height of the negative terminal 222 can be measured by irradiating the welding surface 222a of the negative terminal 222 exposed from the concave portion 337 with a laser beam from, for example, a laser displacement meter. In other words, the through hole 335 has a portion into which the protruding portion 223 is inserted and a portion for measuring the height of the negative electrode terminal 222 that are integrally provided. Even in comparison, the total opening area of the bus bar 332 can be reduced. Therefore, it is possible to suppress a decrease in the strength of the bus bar 332 itself.

Furthermore, if the total opening area of bus bar 332 is reduced, it is possible to suppress an increase in electrical resistance.

Also, the second portion is a concave portion 337 recessed outwardly with respect to the first portion.

According to this, by forming the second portion as the concave portion 337, the size of the second portion can be made compact. As a result, the total opening area of bus bar 332 can be made smaller. Therefore, it is possible to suppress a decrease in the strength of the bus bar 332 itself and to further suppress an increase in electrical resistance.

In addition, two recesses 337 are provided in the periphery of the through hole 335 .

Here, if there is only one concave portion in the peripheral portion of the through hole 335, the projecting portion 223 of the negative electrode terminal 222 may lean toward the concave portion during assembly, and the concave portion may narrow. However, if there are two recesses 337, even if the protruding part 223 moves toward one of the recesses 337 during assembly, the other recess 337 is less likely to narrow. Therefore, a space for measuring the height of the negative electrode terminal 222 can be secured.

Also, the two recesses 337 are arranged along the current flow direction in the bus bar 332 .

According to this, since the two recesses 337 are arranged along the direction of current flow in the busbar 332 , the cross-sectional area of the busbar 332 in the plane perpendicular to the flow direction is not narrowed by the recesses 337 . Thereby, an increase in electrical resistance caused by the concave portion 337 can be suppressed.

Also, the two recesses 337 are arranged along the flow direction, so that they are arranged at positions facing each other with the center of the through-hole 335 interposed therebetween. In other words, even if the projecting portion 223 moves toward one of the recessed portions 337 during assembly, the other recessed portion 337 will not be narrowed. Therefore, a space for measuring the height of the negative electrode terminal 222 can be reliably secured.

Bus bar 332 has a plurality of through holes 335, and the second portions (recesses 337) of the plurality of through holes 335 are arranged on the same straight line (virtual straight line L1).

According to this, since the second portions of the plurality of through-holes 335 are arranged on the same straight line, for example, by linearly scanning the laser from the laser displacement meter, each through-hole can be It is possible to easily measure the height of the electrode terminal to be applied.

[Modification 1]
In the above embodiment, the case where the second portion of the peripheral portion of the through-hole 335 is the concave portion 337 is exemplified. However, the second portion may have any shape as long as it is farther from the protrusion 223 than the first portion and does not follow the outer periphery of the protrusion 223 . In Modification 1, the corner portion 337a is illustrated as an example of the second portion. FIG. 6 is a top view showing a busbar 332A according to Modification 1. As shown in FIG. Specifically, FIG. 6 is a diagram corresponding to FIG. In the following description, parts that are the same as those in the above-described embodiment are denoted by the same reference numerals, and description thereof may be omitted.

As shown in FIG. 6, the through hole 335a of the busbar 332A has two arcuate portions 336 and two corners 337a. The corner portion 337a smoothly continues from one end of each of the two arcuate portions 336 and has an outwardly widening R shape. For this reason, the corner portion 337a faces a portion of the projecting portion 223, but has an outer shape that does not resemble the portion. Further, the corner portion 337a is further away from the projecting portion 223 than the arc-shaped portion 336 is.

Since the corner portion 337a, which is the second portion, has the shape described above, the corner portion 337a can be used as a space for height measurement. Note that although the R-shaped corner 337a is illustrated in Modification 1, it may be an angular corner. Further, the second portion may have a shape other than the concave portion 337 and the corner portion 337a illustrated in the above embodiment.

[Modification 2]
In the above-described embodiment, the case where the same through-holes 335 are formed in all the flat plate portions 31 of the bus bar 332 has been exemplified. However, the shape of the through holes 335 provided in each flat plate portion 31 may be different. Modification 2 exemplifies a case where the through hole 335b of the flat plate portion 31 joined to the positive electrode terminal 221 and the through hole 335 of the flat plate portion 31 joined to the negative electrode terminal 222 have different shapes. FIG. 7 is a top view showing a busbar 332B according to Modification 2. As shown in FIG. Specifically, FIG. 7 is a diagram corresponding to FIG.

As shown in FIG. 7, in the bus bar 332B, the flat plate portion 31 joined to the negative terminal 222 is provided with the same through hole 335 as in the above embodiment. On the other hand, the flat plate portion 31b joined to the positive electrode terminal 221 is formed with an elongated rectangular through-hole 335b along the X-axis direction. Also, the through hole 335 b is arranged on the same straight line together with the concave portion 337 of the through hole 335 .

Here, since the positive electrode terminal 221 is not provided with a projecting portion, the through hole 335b only needs to secure a space for height measurement. That is, since the through holes 335b can be made smaller than the through holes 335, the total opening area of the bus bar 332B can be further reduced. As a result, it is possible to suppress a decrease in the strength of the bus bar 332B itself and to further suppress an increase in electrical resistance.

6 and 7, the recess 337a in FIG. 6, and the through hole 335b and the recess 337 in FIG. It is possible to implement it suitably. In these cases, as in the above-described embodiment, the welding region is defined in the Y-axis direction from the recess 337a in FIG. It is possible to form an arc in the XY plane along the arc 336 with the start and end of the weld spaced apart by a distance. In addition, the welding region can also form a linear welding trajectory in the flat plate portion 31, for example, in the X-axis direction.

[others]
Although the power storage device according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and modifications. In other words, it should be considered that the embodiments and modifications disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the meaning and scope of equivalents of the scope of the claims.

For example, in the above-described embodiment, the case where two second portions (recesses 337) are provided for one through hole 335 has been exemplified. However, the number of second portions installed in one through-hole may be one or three or more.

Moreover, in the above-described embodiment, the case where the two second portions in one through-hole 335 are arranged along the current flow direction (X-axis direction) has been exemplified. However, the two second parts need not be arranged along the direction of current flow.

Moreover, in the above-described embodiment, the case where the second portions of the plurality of through holes 335 are arranged on the same straight line has been exemplified. However, the second portions of the plurality of through holes 335 do not have to be arranged on the same straight line.

Moreover, the form constructed by arbitrarily combining the constituent elements included in the above embodiment and its modifications is also included in the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to a power storage device having a power storage element such as a lithium ion secondary battery.

1 Power Storage Device 10 Exterior Body 11 Outer Lid 12 Body Part 17 Busbar Plate 17a Busbar Opening 20 Storage Element 21 Container 22 Electrode Terminal 23 Insulating Members 31, 31b Flat Plate Part 32 Curved Part 33, 331, 332, 332A, 332B Busbar 60 , 70 busbar cover 80 connection units 91, 92 external terminal 221 positive terminals 221a, 222a welding surface 222 negative terminal 223 projecting portions 335, 335a, 335b through hole 336 arc-shaped portion (first portion)
337 recess (second part)
337a corner (second part)
L1 Virtual straight line S Gap

Claims (1)

an exterior body;
a plurality of power storage elements housed in the exterior body;
and a bus bar that connects the electrode terminals of the storage element,
The electrode terminal has a welding surface to which the bus bar is welded and a projection projecting from the welding surface,
the bus bar has a plurality of through holes into which the protrusions are inserted;
A peripheral edge portion of the through hole is provided with a first portion along the outer periphery of the projecting portion and a second portion not along the outer periphery,
the second portions of each of the plurality of through holes are arranged on the same straight line ,
The second portion is a recess that is recessed outward with respect to the first portion,
Two recesses are provided in the periphery of the through hole,
The two recesses are arranged along the direction of current flow in the busbar.
storage device.

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