JP7400488B2 - Power storage device - Google Patents

Description

The present invention relates to a power storage device including a power storage element and an exterior body.

Conventionally, a power storage element (battery) is housed in a pair of divided exterior bodies (battery cases), and a joint is formed by ultrasonically welding the connecting surfaces of the pair of exterior bodies. A power storage device (battery assembly) in which bodies are joined together is known (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2001-313014

A power storage element has a characteristic of gradually expanding as it is charged and discharged. Therefore, as the power storage element expands, the power storage element presses against the inner surface of the exterior body, and the stress acting on the joint of the exterior body also increases, which may cause damage to the joint.

An object of the present invention is to provide a power storage device that can suppress damage to joints of an exterior body.

In order to achieve the above object, a power storage device according to one embodiment of the present invention includes a plurality of power storage elements stacked in a predetermined direction and an exterior body that houses the plurality of power storage elements, and the exterior body has an opening. a first member that has a section and accommodates a plurality of power storage elements; a second member that is joined to the first member while covering the opening; the first member and the second member are The first member has a joint part joined to each other along the periphery of the opening, and the part corresponding to a predetermined direction at the joint part of the first member has a larger area per unit length than other parts. A part is provided in at least a part of the part.

For example, when a plurality of power storage elements are stacked so that the long sides of rectangular parallelepiped power storage elements overlap, the plurality of power storage elements are likely to expand in the direction in which they are lined up (predetermined direction). That is, a larger pressing force acts on a portion of the first member corresponding to a predetermined direction than on other portions. However, in this aspect, at least a portion of the joint portion of the first member is provided with an enlarged portion having a larger area per unit length than other portions at a portion corresponding to a predetermined direction. In the enlarged part, the bonding area is larger than in other parts, so the shear strength is also larger. Thereby, even if a larger pressing force acts than other parts, damage to the enlarged part can be suppressed. In this way, it is possible to provide a power storage device in which damage to the joint portion is suppressed.

Further, at least one of the pair of sides that are the edges of the enlarged portion may have an uneven structure including at least one concave portion and one convex portion.

According to this, since the uneven structure is provided on at least one of the pair of sides that are the edges of the enlarged portion, the shape becomes more intricate than a straight structure. Therefore, the bonding area can be expanded, and the bonding strength at the enlarged portion can be increased. Therefore, damage to the expanded portion due to expansion of the power storage element can be more reliably suppressed.

Further, among a pair of sides that are edges of the enlarged portion, one side may have an uneven structure, and the other side may be formed in a straight line.

Here, the other side that forms the enlarged portion is formed in a straight line and is less likely to deform than the one side that has an uneven structure. Therefore, even if the power storage element expands and the enlarged portion receives a pressing force, the amount of deformation is suppressed, so that damage to the enlarged portion can be more reliably suppressed.

Further, the enlarged portion may be arranged at the center of a portion corresponding to a predetermined direction at the joint portion of the first member.

Here, when a plurality of power storage elements expand, the central portion of the joint portion of the first member corresponding to a predetermined direction is most likely to deform due to the pressing force at the time of expansion. If the enlarged portion is provided in the center, the center can be reinforced and damage to the enlarged portion can be more reliably suppressed.

Further, the portion of the second member that is joined to the enlarged portion at the joint portion may be formed in the same shape as the enlarged portion.

According to this, since the part of the joint of the second member that is joined to the enlarged part is formed in the same shape as the enlarged part, the joint area can also be increased on the second member side, and the shear The strength can also be increased. In particular, if the portion of the second member and the enlarged portion are overlapped so as to coincide with each other, the improvement in shear strength is more remarkable. Therefore, damage to the joint can be more reliably suppressed.

According to the power storage device of the present invention, damage to the joint portion of the exterior body can be suppressed.

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 disassembled. FIG. 2 is a top view showing a schematic configuration of a main body according to an embodiment. FIG. 2 is a bottom view showing a schematic configuration of an outer lid according to an embodiment. FIG. 3 is a cross-sectional view showing a joint structure between the main body and the outer lid according to the embodiment. FIG. 2 is a cross-sectional view showing a cross-sectional shape of a part of a joint according to an embodiment. FIG. 7 is a top view showing a schematic configuration of a main body according to Modification 1. FIG. FIG. 7 is a bottom view showing a schematic configuration of an outer lid according to Modification 1. FIG. FIG. 7 is a cross-sectional view showing a joint according to modification example 2. FIG. 7 is a cross-sectional view showing a joint according to modification example 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, power storage devices according to embodiments of the present invention and modifications thereof will be described with reference to the drawings. Note that the embodiments and modifications thereof described below are comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments and modifications thereof are merely examples, and do not limit the present invention. Further, in each figure, dimensions etc. are not strictly illustrated.

In addition, in the following description and drawings, the direction in which the power storage elements are arranged, the direction in which the power storage elements face the long sides of the container, or the thickness direction of the container is defined as the X-axis direction. Further, the direction in which the electrode terminals in one power storage element are arranged or the direction in which the short sides of the container of the power storage element face each other is defined as the Y-axis direction. Further, the direction in which the main body and the outer cover are lined up in the exterior body of the power storage device, or the up-down direction is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect with each other (orthogonal in the following embodiments and modifications thereof). Note that depending on the mode of use, the Z-axis direction may not be the vertical direction, but for convenience of explanation, the Z-axis direction will be described as the vertical direction below. Furthermore, in the following description, for example, the plus side in the X-axis direction refers to the side in the direction of the arrow of the X-axis, and the minus side in the X-axis direction refers to the side opposite to the plus side in the X-axis direction. The same applies to the Y-axis direction and the Z-axis direction. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the directions or orientations are not strictly speaking. For example, when two directions are orthogonal, it does not only mean that the two directions are completely orthogonal, but also that they are substantially orthogonal, that is, there is a difference of only a few percent, for example. It also means to include.

[General explanation of power storage device]
First, a general description of the power storage device 1 according to the embodiment will be given using FIGS. 1 and 2. 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 power storage device 1 according to the embodiment is disassembled.

Power storage device 1 is a device that can charge electricity from the outside and discharge electricity to the outside, and in this embodiment, has a substantially rectangular parallelepiped shape. For example, the power storage device 1 is a battery module (battery assembly) used for power storage, power supply, or the like. Specifically, the power storage device 1 is used for driving or starting an engine of a moving object such as a car, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. It is used as a battery etc. Examples of the above-mentioned vehicle include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline vehicle. Examples of the above-mentioned railway vehicles for electric railways include electric trains, monorails, and linear motor cars. Furthermore, the power storage device 1 can also be used as a stationary battery or the like used for home use, a generator, or the like.

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 plurality of power storage elements 20. The exterior body 10 includes a main body 11 that accommodates a plurality of power storage elements 20, a busbar plate 17 arranged above the plurality of power storage elements 20, and an outer lid 12 that covers the busbar plate 17 above.

Exterior body 10 is a rectangular (box-shaped) container (module case) that constitutes the exterior body of power storage device 1 . That is, the exterior body 10 is a member that fixes the plurality of power storage elements 20, the bus bar plate 17, etc. in a predetermined position, and protects these elements from impact and the like.

The main body portion 11 is an example of a first member having an opening 111. The main body part 11 is a bottomed rectangular cylindrical member with an open upper part, and the open part is an opening part 111. The opening 111 has a substantially rectangular shape in plan view. A wall portion 50 is provided at the upper end of the main body portion 11 and continuously surrounds the opening portion 111 over the entire circumference. Inside the opening 111 of the main body 11, in addition to the plurality of power storage elements 20 and the busbar plate 17, there are a plurality of busbars 33 held by the busbar plate 17, a connection unit 80 including a control circuit, etc., and a pair of ends. A plate 39 is housed therein.

The outer lid 12 is a rectangular member that closes the opening 111 of the main body 11, and is an example of a second member. The outer lid 12 is joined to the main body 11 while covering the opening 111 of the main body 11 . Details of this joining structure will be described later.

The outer lid 12 has an external terminal 81 on the positive side and an external terminal 82 on the negative side. The external terminals 81 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 81 and 92. Charges and discharges electricity to the outside. The external terminals 81 and 92 are made of a conductive member made of a metal such as a copper alloy such as brass, copper, aluminum, or an aluminum alloy. The main body portion 11 is a bottomed rectangular cylindrical housing with an opening formed therein, and accommodates the power storage element 20 and the like.

The main body 11 and outer lid 12 of the exterior body 10 are made of, for example, polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (modified (including PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyether It is formed of an insulating member such as sulfone (PES), ABS resin, or a composite material thereof, or a metal coated with an insulating coating. The exterior body 100 thereby prevents the power storage element 20 and the like from coming into contact with external metal members and the like. Note that the exterior body 100 may be formed of a conductive member such as metal, as long as the electrical insulation of the power storage element 20 and the like is maintained.

The power storage element 20 is a secondary battery (single battery) that can charge and discharge electricity, and more specifically, it is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. . The power storage element 20 has a flat rectangular parallelepiped shape (prismatic shape), and in this embodiment, eight power storage elements 20 are arranged in the X-axis direction. Note that the shape of the power storage elements 20 and the number of power storage elements 20 arranged are not limited. Furthermore, the power 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, a capacitor, or a battery that can be charged by the user. It may also be a primary battery that can use the stored electricity without having to do so.

Specifically, the power storage element 20 includes a metal container 21. The container 21 is formed into a substantially rectangular parallelepiped shape, and has a pair of long sides 211 and a pair of short sides 212 adjacent to the pair of long sides 211. The pair of long sides 211 are opposite to each other in the X-axis direction, and the pair of short sides 212 are opposite to each other in the Y-axis direction. Each of the plurality of power storage elements 20 is stacked so that the long sides 211 of the containers 21 face each other, and are housed in the main body 11 .

The 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 (not shown) is interposed between the lid portion and the positive electrode terminal 221 and the negative electrode terminal 222, and the lid portion and the positive electrode terminal 221 and the negative electrode terminal 222 are insulated by this insulating member.

The positive electrode terminal 221 and the negative electrode terminal 222 are electrode terminals arranged to protrude from the lid portion of the container 21 toward the busbar plate 17 side (upward, that is, toward the positive side in the Z-axis direction). By connecting the positive electrode terminal 221 and the negative electrode terminal 222 to external terminals 81 and 82 via at least one bus bar 33 and the connection unit 80, the power storage device 1 charges electricity from the outside and also transfers it to the outside. Can discharge electricity. Note that the lid portion of the container 21 may be provided with a liquid injection part for injecting the electrolyte solution, a gas discharge valve for discharging gas to release the pressure when the pressure inside the container 21 increases, and the like. Further, inside the container 21, an electrode body (also referred to as a power storage element or a power generation element), a current collector (a positive electrode current collector and a negative electrode current collector), etc. are arranged, and an electrolytic solution (non-aqueous electrolyte) etc. Although it is enclosed, detailed explanation will be omitted.

The bus bar 33 has a rectangular shape that is disposed on at least two power storage elements 20 while being held by the bus bar plate 17 and electrically connects the positive terminals 221 and negative terminals 222 of the at least two power storage elements 20. It is a plate-like member. The bus bar 33 is made of a conductive member made of metal, such as copper, copper alloy, aluminum, or aluminum alloy. In this embodiment, five bus bars 33 are used to connect two power storage elements 20 in parallel to form four sets of power storage element groups, and the four sets of power storage element groups are connected in series. Connected.

Further, the connection unit 80 is a unit having a plurality of bus bars, a control board, etc., and connects a power storage element group consisting of eight power storage elements 20 and external terminals 81 and 82. The control board included in the connection unit 80 has a plurality of electrical components, and these electrical components form a detection circuit that detects the state of each power storage element 20, a control circuit that controls charging and discharging, etc. 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. Moreover, the connection unit 80 does not need to have a control board. In this case, for example, a control device disposed outside 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 disposed above the plurality of power storage elements 20 (on the side where the positive electrode terminal 221 and the negative electrode terminal 222 are arranged), and in this embodiment, the busbar plate 17 is a member that holds the busbar 33. It is. More specifically, the busbar plate 17 is a member that holds the plurality of busbars 33, the connection unit 80, and other wiring (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 each of the plurality of busbars 33 and expose a part of each of the plurality of busbars 33 to the side of the plurality of power storage elements 20. . Furthermore, by being fixed to the main body portion 11, the busbar plate 17 also has the role of, for example, regulating the movement of the plurality of power storage elements 20 upward (toward the positive side in the Z-axis direction).

Note that the busbar plate 17 arranged above the plurality of power storage elements 20 may be called, for example, a "busbar frame" or an "inner lid." The busbar plate 17 is made of, for example, PC, PP, PE, PS, PPS, PPE (including modified PPE), PET, PBT, PEEK, PFA, PTFE, PES, ABS resin, or a composite material thereof. It is made of an insulating member or a metal coated with an insulating coating.

The pair of end plates 39 are rectangular plates disposed within the main body 11 at positions that collectively sandwich the plurality of power storage elements 20 . Specifically, the pair of end plates 39 are arranged parallel to the YZ plane at positions sandwiching the plurality of power storage elements 20 in the X-axis direction. That is, the pair of end plates 39 are arranged so as to overlap with the long side surface 211 of the container 21 of the electricity storage element 20 arranged at the outermost side. The end plate 39 is made of an insulating member such as PC, PP, PE, PS, PPS, PPE (including modified PPE), PET, PBT, PEEK, PFA, PTFE, PES, ABS resin, or a composite material thereof. Or, it is made of metal or the like with an insulating coating.

[Joining structure between main body and outer cover]
Next, the joining structure between the main body portion 11 and the outer cover 12 will be explained. First, the parts related to the joint structure of the main body part 11 will be explained. FIG. 3 is a top view showing a schematic configuration of the main body portion 11 according to the embodiment. In addition, in FIG. 3, the main body part 11 is shown in a state before the outer cover 12 is joined.

As shown in FIG. 3, the opening 111 of the main body 11 is continuously surrounded by the wall 50 all around. The wall portion 50 includes a pair of first wall portions 51 facing each other in the Y-axis direction and a pair of second wall portions 52 facing each other in the X-axis direction.

The first wall portion 51 extends in the X-axis direction, and the width H1 (thickness in the Y-axis direction) of its upper end portion is uniform as a whole.

The second wall portion 52 extends in the Y-axis direction, and is formed so that the width (thickness in the X-axis direction) of its upper end portion varies along the Y-axis direction. For example, of a pair of edges that are the edges of the upper end of the second wall portion 52, the outer edge is defined as the outer edge 521, and the inner edge is defined as the inner edge 522. The outer edge portion 521 is formed in a straight line along the Y-axis direction as a whole. The inner edge portion 522 has a concavo-convex structure 525 consisting of a plurality of concave portions 523 and convex portions 524. The recesses 523 and the protrusions 524 are alternately arranged in the Y-axis direction.

Each concave portion 523 is a portion between a pair of adjacent convex portions 524. Each recess 523 has the same shape in plan view (top view). The width H2 (thickness in the X-axis direction) of each recess 523 is equal to the width H1 of the upper end of the first wall 51.

Each convex portion 524 is a portion between a pair of adjacent concave portions 523, and a portion of the convex portion 524 protrudes inward from the concave portions 523. Each convex portion 524 has the same shape in plan view. In each convex portion 524, a portion (bottom portion 5241) continuous with the concave portion 523 extends uniformly in the Y-axis direction with a width H2. Further, a portion of each convex portion 524 that protrudes from the bottom portion 5241 is referred to as a tip portion 5242. A hollow portion 526 having a rectangular shape in plan view is formed in the center of the tip portion 5242 .

Here, a length longer than the length L2 of the recess 523 in the Y-axis direction is defined as a unit length L1. At the upper end of the first wall portion 51, the area within the unit length L1 is L1×H1. This is the same at any location on the upper end of the first wall portion 51. On the other hand, at the upper end of the second wall portion 52, at least a portion of the recess 523 and at least a portion of the convex portion 524 coexist within the unit length L1. That is, at any location on the upper end of the second wall portion 52, the unit length L1 includes at least a portion of the protruding end portion 5242 in addition to the location having the overall width H2. Therefore, the area within the unit length L1 at the upper end of the second wall portion 52 is larger than the area within the unit length L1 at the upper end of the first wall portion 51 at any location.

Next, parts related to the joint structure of the outer lid 12 will be explained. FIG. 4 is a bottom view showing a schematic configuration of the outer lid 12 according to the embodiment. As shown in FIG. 4, the inner top surface 121 of the outer lid 12 is provided with external terminals 81 and 82 and a housing recess 122. Specifically, the external terminals 81 and 82 are fixed so as to pass through the outer lid 12 so that their bases are exposed from the inner top surface 121. The accommodation recess 122 is a part recessed upward from the inner top surface 121, and the connection unit 80 and the like are accommodated therein.

A skirt portion 123 extending downward is provided around the entire periphery of the outer lid 12. The skirt portion 123 is formed into a circumferentially continuous rectangular frame shape when viewed from below. Furthermore, in the outer lid 12, a protruding strip 60 that protrudes downward is provided between the inner top surface 121 and the skirt portion 123. The protruding portion 60 is formed in a rectangular frame shape continuous in the circumferential direction when viewed from the bottom. The shape of the protruding portion 60 in plan view is the same as the shape of the wall portion 50 in plan view.

The protruding portion 60 includes a pair of first protruding portions 61 facing each other in the Y-axis direction and a pair of second protruding portions 62 facing each other in the X-axis direction.

The first protruding portion 61 is a portion joined to the upper end portion of the first wall portion 51 and has a shape corresponding to the first wall portion 51. Specifically, the first protruding portion 61 extends in the X-axis direction, and the width H11 (thickness in the Y-axis direction) of the lower end thereof is uniform as a whole. The width H11 is equivalent to the width H1 of the upper end portion of the first wall portion 51.

The second protruding portion 62 is a portion joined to the upper end portion of the second wall portion 52 and has a shape corresponding to the second wall portion 52. Specifically, the second convex strip 62 extends in the Y-axis direction, and is formed so that the width (thickness in the X-axis direction) of the lower end thereof varies along the Y-axis direction. . For example, of a pair of sides that are the edges of the lower end of the second convex strip 62, the outer side is defined as the outer edge part 621, and the inner side is defined as the inner edge part 622. The outer edge portion 621 is formed in a straight line along the Y-axis direction as a whole. The inner edge portion 622 has a concavo-convex structure 625 consisting of a plurality of concave portions 623 and convex portions 624. The recesses 623 and the protrusions 624 are alternately arranged in the Y-axis direction.

Each recess 623 is a portion between a pair of adjacent protrusions 624. Each recess 623 has the same shape in plan view (bottom view). The width H12 (thickness in the X-axis direction) of each recess 623 is equal to the width H11 of the lower end portion of the first protruding strip 61.

Each convex portion 624 is a portion between a pair of adjacent concave portions 623, and a portion of the convex portion 624 protrudes inward from the concave portions 623. Each convex portion 624 has the same shape in plan view. In each convex portion 624, a portion (bottom portion 6241) continuous with the concave portion 623 extends uniformly in the Y-axis direction with a width H12. Further, a portion of each convex portion 624 that protrudes from the bottom portion 6241 is defined as a tip portion 6242. A hollow portion 626 having a rectangular shape in plan view is formed in the center of the tip portion 6242 . In this way, the lower end of the second convex strip 62 has the same shape as the upper end of the second wall 52. Therefore, the area within the unit length L1 at the lower end of the second protruding portion 62 is larger than the area within the unit length L1 at the lower end of the first protruding portion 61 at any location.

FIG. 5 is a cross-sectional view showing a joint structure between the main body portion 11 and the outer lid 12 according to the embodiment. FIG. 5 is a cross-sectional view of the main body 11 and the outer cover 12 in a state in which they are joined, as seen in a cut plane parallel to the XZ plane including the VV line in FIGS. 3 and 4. FIG. 5 shows the power storage element 20 and the bus bar 33 in a plan view.

Here, thermal welding is employed to join the main body portion 11 and the outer cover 12. Thermal welding is a method of joining members to be joined by melting them with heat, then bringing them into close contact with each other and re-hardening them. Examples of thermal welding include heat sealing and ultrasonic welding. Note that the main body portion 11 and the outer cover 12 may be bonded together using an adhesive. Even when joining using an adhesive, the members to be joined are melted and re-hardened, but if the joint location is analyzed after hardening, the adhesive remains at that location. Therefore, even after joining, it is possible to determine whether the joining is by thermal welding or by adhesive.

During thermal welding, the entire circumference of the tip (upper end) of the wall portion 50 of the main body portion 11 is heated and melted. On the other hand, in the outer lid 12, the entire circumference of the lower end of the convex strip 60 is melted. With both of them melted, the outer lid 12 is brought close to the main body 11 and the entire circumference of the lower end of the protruding strip 60 is pressed against the entire circumference of the tip of the wall portion 50, thereby causing the melted parts to contact each other. Mix together.

After a certain period of time has elapsed in an unheated state, the mixed parts are hardened, integrated, and joined. This joint portion is the joint portion 90. The joint portion 90 is continuously provided along the entire circumference of the opening portion 111. In other words, the main body 11 and the outer lid 12 have a joint 90 joined along the entire circumference of the opening 111. In addition, in FIG. 5, with respect to the joint part 90, the tip part (lower end part) of the second protruding part 62 in the protruding part 60, the tip part (upper end part) of the second wall part 52 in the wall part 50, Although the interface between the two is shown in the diagram, in reality, the two are hardened in a mixed state, so no interface exists. The joint portion 90 seals the main body portion 11 and the outer cover 12 over the entire circumference, ensuring airtightness.

The joint 90 includes a pair of first joints 91 facing each other in the Y-axis direction and a pair of second joints 92 facing each other in the X-axis direction.

FIG. 6 is a cross-sectional view showing a cross-sectional shape of a part of the joint portion 90 according to the embodiment. Specifically, (a) of FIG. 6 shows a part of the first joint part 91 corresponding to the part surrounded by the two-dot chain line in FIGS. 3 and 4. FIG. 6(b) shows a part of the second joint 92 corresponding to the part surrounded by the broken line in FIGS. 3 and 4. FIG.

As described above, the lower end of the protruding strip 60 and the upper end of the wall 50 have the same shape. Therefore, the joint portion 90 is formed by thermally welding the lower end portion of the protruding portion 60 and the upper end portion of the second wall portion 52 so as to coincide with each other. Specifically, as shown in FIG. 6(a), in the first joint portion 91, the lower end portion of the first protruding strip portion 61 and the upper end portion of the first wall portion 51 are overlapped. ing. That is, it can be said that the outline of the first joint portion 91 is also the outline of the lower end of the first convex strip portion 61 and the outline of the upper end of the first wall portion 51.

Further, as shown in FIG. 6B, in the second joint portion 92, the lower end portion of the second protruding strip portion 62 and the upper end portion of the second wall portion 52 are overlapped so as to coincide with each other. That is, it can be said that the outline of the second joint portion 92 is also the outline of the lower end of the second convex strip portion 62 and the outline of the upper end of the second wall portion 52. Therefore, among the pair of sides that are the edges of the second joint portion 92, the outer edge portion 921 is the outer edge portion 521 of the second wall portion 52, and the outer edge portion 621 of the second convex strip portion 62. It can be said that Further, of the pair of sides that are the edges of the second joint portion 92, the inner edge portion 922 is the inner edge portion 522 of the second wall portion 52 and the inner edge portion 622 of the second convex strip portion 62. I can say that there is. The inner edge portion 922 of the second joint portion 92 has an uneven structure 925 consisting of an uneven structure 525 of the second wall portion 52 and an uneven structure 625 of the second protruding strip portion 62 . The uneven structure 925 includes a plurality of recesses 923 consisting of each recess 523 of the second wall 52 and each recess 623 of the second protrusion 62, and each convex 524 of the second wall 52 and the second protrusion 62. It has a plurality of convex parts 924 consisting of each convex part 624.

Further, as described above, the area within the unit length L1 at the upper end of the second wall portion 52 is larger than the area within the unit length L1 at the upper end of the first wall portion 51 at any location. Further, the area within the unit length L1 at the lower end of the second protruding portion 62 is larger than the area within the unit length L1 at the lower end of the first protruding portion 61 at any location. From this, the same can be said of the first joint portion 91 and the second joint portion 92. That is, the second joint portion 92 can be said to be an enlarged portion having a larger area per unit length L1 than the first joint portion 91 as a whole. Therefore, the second joint portion 92 can exhibit higher shear strength than the first joint portion 91.

[Effects etc.]
As described above, according to the power storage device 1 according to the present embodiment, the plurality of power storage elements 20 stacked in the X-axis direction (predetermined direction) and the exterior body 10 that accommodates the plurality of power storage elements 20 are We are prepared. The exterior body 10 includes a main body 11 (first member) that has an opening 111 and accommodates a plurality of power storage elements 20, and an outer lid 12 (first member) that is joined to the main body 11 while covering the opening 111. a second member). The main body portion 11 and the outer lid 12 have a joint portion 90 that is joined to each other along the periphery of the opening portion 111 . The second joint part 92 corresponding to the X-axis direction in the joint part 90 of the main body part 11 is an enlarged part having a larger area per unit length L1 than the first joint part 91.

Here, when a plurality of power storage elements 20 are stacked such that the long sides 211 of the rectangular parallelepiped power storage elements 20 overlap, the plurality of power storage elements 20 are likely to expand in the direction in which they are lined up (X-axis direction). That is, a larger pressing force acts on the second joint portion 92 in the main body portion 11 than on the first joint portion 91 . However, the second joint part 92 of the main body part 11 is an enlarged part having a larger area per unit length than the first joint part 91. Therefore, since the enlarged portion has a larger bonding area than the first bonded portion 91, the shear strength also increases. Thereby, even if a larger pressing force than the first joint part 91 is applied, damage to the second joint part 92 can be suppressed. In this way, it is possible to provide power storage device 1 in which damage to joint portion 90 is suppressed.

Further, at least one side (inner edge portion 922 ) of the pair of sides that are the edges of the second joint portion 92 has an uneven structure 925 that includes at least one recess 923 and one protrusion 924 .

According to this, since the uneven structure 925 is provided on at least one side (inner edge portion 922) of the pair of edges that are the edges of the second joint portion 92, which is the enlarged portion, the linear structure is It has a more complicated shape. Therefore, the bonding area can be expanded, and the bonding strength at the second bonding portion 92 can be increased. Therefore, damage to second joint portion 92 caused by expansion of power storage element 20 can be more reliably suppressed.

In particular, when joining by welding, the first joining part 91 and the second joining part 92 can be melted and joined under the same melting conditions. Thereby, it is possible to easily increase the bonding strength while expanding the bonding area with the concavo-convex structure 925 of the second bonding portion 92.

Furthermore, among the pair of sides that are the edges of the second joint 92, one side (inner edge 922) has an uneven structure 925, and the other side (outer edge 921) is formed in a straight line. .

Here, the outer edge portion 921 is formed in a straight line and is less likely to deform than the inner edge portion 922 having the uneven structure 925. Therefore, even if the power storage element 20 expands and the second joint portion 92 receives a pressing force, the amount of deformation is suppressed, so that damage to the second joint portion 92 can be suppressed more reliably.

Further, the second joint portion 92, which is an enlarged portion, is arranged at the center of the portion of the main body portion 11 that corresponds to the X-axis direction.

Here, when the plurality of power storage elements 20 expand, in the portion of the main body 11 corresponding to the X-axis direction (the direction in which the power storage elements 20 are lined up), the central part is most likely to deform due to the pressing force at the time of expansion. . If the enlarged part (second joint part 92) is provided in the central part, the central part can be reinforced, and damage to the enlarged part can be suppressed more reliably.

Further, the second joint portion 92 of the outer lid 12 is formed in the same shape as the second joint portion 92 of the main body portion 11 .

According to this, since the second joint part 92 of the outer cover 12 is formed in the same shape as the second joint part 92 of the main body part 11, the joint area can be increased also on the outer cover 12 side, Shear strength can also be increased. In particular, if the second joint part 92 of the outer lid 12 and the second joint part 92 of the main body part 11 are overlapped so as to coincide with each other, the improvement in shear strength is more remarkable. Therefore, damage to the joint portion 90 can be more reliably suppressed.

[Modification 1]
In the above embodiment, a case has been described in which the inner edge 922 of the second joint portion 92 has the uneven structure 925 and the outer edge 921 is formed linearly. In this first modification, a power storage device in which the inner edge and the outer edge of the second joint portion each have an uneven structure will be described. In the following description, parts equivalent to those in the above embodiment may be given the same reference numerals and the description thereof may be omitted.

FIG. 7 is a top view showing a schematic configuration of the main body portion 11a according to the first modification. Specifically, FIG. 7 is a diagram corresponding to FIG. 3.

As shown in FIG. 7, the opening 111a of the main body 11a is continuously surrounded by the wall 50a. The wall portion 50a includes a pair of first wall portions 51 facing each other in the Y-axis direction and a pair of second wall portions 52a facing each other in the X-axis direction.

The second wall portion 52a extends in the Y-axis direction, and is formed so that the width (thickness in the X-axis direction) of its upper end portion varies along the Y-axis direction. For example, of a pair of edges that are the edges of the upper end of the second wall portion 52a, the outer edge is defined as the outer edge 521a, and the inner edge is defined as the inner edge 522.

The outer edge portion 521a has a concavo-convex structure 529a consisting of a plurality of concave portions 527a and convex portions 528a. The concave portions 527a and the convex portions 528a are alternately arranged in the Y-axis direction. Furthermore, each recess 527a of the outer edge 521a is arranged at a position corresponding to each convex portion 524 of the inner edge 522. Similarly, each convex portion 528a of the outer edge portion 521a is arranged at a position corresponding to each concave portion 523 of the inner edge portion 522.

The width H3 between the bottom surface of each concave portion 527a of the outer edge portion 521a and the tip end surface of each convex portion 524 of the inner edge portion 522 is equal to the width H1 of the upper end portion of the first wall portion 51. Similarly, the width H4 between the tip surface of each convex portion 528a of the outer edge portion 521a and the bottom surface of each recessed portion 523 of the inner edge portion 522 is equal to the width H1 of the upper end portion of the first wall portion 51. When the second wall portion 52a is viewed continuously in the Y-axis direction, there is a portion where the width H3 and the width H4 overlap. In this portion, the width is wider than the width H1 of the upper end portion of the first wall portion 51. For example, at the upper end of the first wall portion 51, the area within the unit length L1 is L1×H1. This is the same at any location on the upper end of the first wall portion 51. On the other hand, at the upper end of the second wall portion 52a, there is a portion within the unit length L where the width H3 and the width H4 overlap. That is, the area within the unit length L1 at the upper end of the second wall 52a is larger than the area within the unit length L1 at the upper end of the first wall 51 at any location.

Next, parts related to the joint structure of the outer lid 12a will be explained. FIG. 8 is a bottom view showing a schematic configuration of the outer lid 12a according to the first modification. Specifically, FIG. 8 is a diagram corresponding to FIG. 4.

As shown in FIG. 8, the protruding portion 60a of the outer lid 12a includes a pair of first protruding portions 61 facing each other in the Y-axis direction and a pair of second protruding portions 62a facing each other in the X-axis direction. ing. The lower end of the protruding strip 60a has the same shape as the upper end of the wall 50a.

The second protruding portion 62a is a portion joined to the upper end portion of the second wall portion 52a, and has a shape corresponding to the second wall portion 52a. Specifically, the second convex portion 62a extends in the Y-axis direction, and is formed such that the width (thickness in the X-axis direction) of the lower end thereof varies along the Y-axis direction. . For example, of a pair of sides that are the edges of the lower end of the second convex strip 62a, the outer side is the outer edge 621a, and the inner side is the inner edge 622.

The outer edge portion 621a has a concavo-convex structure 629a consisting of a plurality of concave portions 627a and convex portions 628a. The concave portions 627a and the convex portions 628a are alternately arranged in the Y-axis direction. Furthermore, each recess 627a of the outer edge 621a is arranged at a position corresponding to each convex part 624 of the inner edge 622. Similarly, each convex portion 628a of the outer edge portion 621a is arranged at a position corresponding to each concave portion 623 of the inner edge portion 622.

As described above, the lower end of the protruding strip 60a and the upper end of the wall 50a have the same shape. Therefore, a joint portion (not shown) is formed by heat welding the lower end of the protruding portion 60a and the upper end of the second wall portion 52a so as to coincide with each other.

[Modification 2]
In the embodiment described above, the entire second joint portion 92 is an enlarged portion. However, the enlarged part may be provided only in a part of the second joint part. In this case, it is preferable that the enlarged portion be provided only at the center of the second joint. In Modification 2, a power storage device in which an enlarged portion is provided only in the center of the second joint will be described.

FIG. 9 is a sectional view showing a joint portion 90b according to Modification 2. As shown in FIG. As shown in FIG. 9, in the second joint 92b of the joint 90b, an uneven structure 925b is formed only at the center of the inner edge 922b in the Y-axis direction. In the inner edge portion 922b, the area other than the uneven structure 925b is formed in a straight line. The part where the uneven structure 925 is formed in the second joint part 92b becomes an enlarged part.

Also in this case, the central portion of the second joint portion 92b can be reinforced, and damage to the enlarged portion can be suppressed. In particular, parts other than the central part of the second joint part 92b have a simple structure, so it is possible to reduce the weight.

[Modification 3]
In the embodiment described above, a case has been exemplified in which the second joint portion 92 is provided with the concavo-convex structure 925 to form an enlarged portion. However, as long as the area per unit length L1 is larger than the first joint portion 91, the shape of the enlarged portion may be any shape. In the third modification, a case is illustrated in which the second joint portion 92c has a uniform shape as a whole.

FIG. 10 is a sectional view showing a joint portion 90c according to modification example 3. As shown in FIG. 10, the second joint part 92c of the joint part 90c is formed uniformly over the entire length with a width H5 larger than the width H1 of the first joint part 91. As shown in FIG. Even in this case, the second joint portion 92c can be said to be an enlarged portion having a larger area per unit length L1 than the first joint portion 91 as a whole. Therefore, the second joint portion 92c can exhibit higher shear strength than the first joint portion 91.

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

For example, in the above-mentioned embodiment and its modification example, the case where the planar view shape of the convex strip part 60 of the outer cover 12 is the same as the planar view shape of the wall part 50 was illustrated. However, the shape of the protruding portion of the outer lid 12 in plan view may be different from the shape of the wall portion in plan view. In this case, any shape is sufficient as long as the entire wall portion can fit within the protruding strip. Thereby, the entire wall portion can be joined to the protruding strip portion.

Further, forms constructed by arbitrarily combining the constituent elements included in the above embodiments and their modifications are also included within the scope of the present invention.

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

1 Power storage device 10 Exterior body 11, 11a Main body 12, 12a Outer cover 17 Busbar plate 17a Busbar opening 20 Power storage element 21 Container 33 Busbar 39 End plate 50, 50a Wall 51 First wall 52, 52a Second wall Parts 60, 60a Convex portion 61 First convex portion 62, 62a Second convex portion 80 Connection units 81, 82 External terminals 90, 90b, 90c Joint portion 91 First joint portion 92 Second joint portion (enlarged portion)
92b, 92c Second joint portion 100 Exterior body 111, 111a Opening portion 121 Inner top surface 122 Accommodating recess 123 Skirt portion 211 Long side surface 212 Short side surface 221 Positive electrode terminal 222 Negative electrode terminal 521, 521a, 621, 621a, 921 Outer edge portion 522, 622, 922, 922b Inner edge portion 523, 527a, 623, 627a, 923 Concave portion 524, 528a, 624, 628a, 924 Convex portion 525, 529a, 625, 629a, 925, 925b Uneven structure 526, 626 Hollow portion 5241, 6241 Bottom portion 5242, 6242 Tip part

Claims (5)

a plurality of power storage elements stacked in a predetermined direction;
an exterior body that accommodates the plurality of power storage elements;
The exterior body is
a first member having an opening and housing the plurality of power storage elements;
a second member joined to the first member while covering the opening;
The first member and the second member have a joint portion joined to each other along the periphery of the opening,
In the power storage device, at least a portion of the joint portion of the first member corresponding to the predetermined direction is provided with an enlarged portion having a larger area per unit length than other portions. The power storage device according to claim 1 , wherein at least one of the pair of sides that are edges of the enlarged portion has a concave-convex structure including at least one concave portion and a convex portion. The power storage device according to claim 2, wherein one side of a pair of sides that are edges of the enlarged portion has the uneven structure, and the other side is formed in a straight line. The power storage device according to any one of claims 1 to 3, wherein the enlarged portion is disposed at a central portion of a portion of the joint portion of the first member that corresponds to the predetermined direction. The power storage device according to any one of claims 1 to 4, wherein a portion of the joint portion of the second member that is joined to the enlarged portion is formed in the same shape as the enlarged portion.

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