Battery module

Abstract

A battery module (100) comprises: a battery cell (110); and a housing body (200) that accommodates the battery cell (110). The housing body (200) has a third plate (230) and a fifth plate (250) that are mutually joined by means of a first laser welding part (272). The first laser welding part (272) extends intermittently.

Description

Battery module

[0001] The present invention relates to a battery module.

[0002] In recent years, various battery modules have been developed. A battery module includes battery cells and a housing that houses the battery cells.

[0003] Patent Document 1 describes a battery module. The battery module includes a plurality of battery cells and a module frame that covers the plurality of battery cells. The module frame includes a U-shaped frame and an upper plate that covers the open upper portion of the U-shaped frame. The U-shaped frame and the upper plate are welded to each other by laser welding.

[0004] Patent Document 2 describes a laser welding method in which a continuous weld is formed along a welding plan line, and a pair of notches are provided on both sides of the continuous weld of the workpiece along the welding plan line.

[0005] Special Publication No. 2022-547186 Japanese Patent Application Publication No. 7-75888

[0006] A housing that houses battery cells may have multiple members joined together via laser welds. When multiple members are joined together via laser welds, it may be necessary to prevent welding defects at the laser welds.

[0007] An example of an object of the present invention is to suppress welding defects at laser welds that weld together multiple members of a housing. Other objects of the present invention will become apparent from the description of this specification.

[0008] One aspect of the present invention is as follows: 1. A battery module comprising: a battery cell; and a housing that houses the battery cell, wherein the housing has a plurality of members joined to one another via laser welds, and the laser welds extend intermittently. 2. The battery module described in 1., wherein the plurality of members have a cutout portion in at least one location, and the laser welds are interrupted in the at least one location.

[0009] According to the above-described aspects of the present invention, it is possible to suppress welding defects in the laser welded portions where the multiple members of the housing are welded together.

[0010] 10 is an exploded perspective view of a battery module according to an embodiment of the present invention;

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by similar reference numerals, and the description thereof will be omitted as appropriate.

[0012] FIG. 1 is an exploded top perspective view of a battery module 100 according to an embodiment.

[0013] For the sake of explanation, the X, Y, and Z directions are shown in FIG. 1 and FIG. 2 , which will be described later. The X direction indicates the front-to-rear direction of the battery module 100. The Y direction is perpendicular to the X direction. The Y direction indicates the left-to-right direction of the battery module 100. The Z direction is perpendicular to both the X and Y directions. The Z direction indicates the up-down direction of the battery module 100. The arrows pointing to the X direction, the Y direction, and the Z direction indicate the front, left, and up directions of the battery module 100, respectively. Hereinafter, as necessary, the tip side of an arrow indicating the X direction will be referred to as the +X side, the opposite side of the tip of the arrow indicating the X direction will be referred to as the −X side, the tip side of an arrow indicating the Y direction will be referred to as the +Y side, the opposite side of the tip of the arrow indicating the Y direction will be referred to as the −Y side, the tip side of an arrow indicating the Z direction will be referred to as the +Z side, and the opposite side of the tip of the arrow indicating the Z direction will be referred to as the −Z side. The relationship between the X direction, Y direction, and Z direction and the front-rear direction, left-right direction, and up-down direction of the battery module 100 is not limited to the above example.

[0014] The battery module 100 includes a plurality of battery cells 110 , a plurality of compression pads 120 , a first voltage detection device 130 , a second voltage detection device 140 , and a housing 200 .

[0015] The plurality of battery cells 110 and the plurality of compression pads 120 are stacked alternately in the Y direction. Hereinafter, as necessary, the plurality of battery cells 110 and the plurality of compression pads 120 stacked alternately in the Y direction will be referred to as a stack of battery cells 110. The dimension of each battery cell 110 in the X direction is the dimension in the longitudinal direction of each battery cell 110. The dimension of each battery cell 110 in the Z direction is the dimension in the lateral direction of each battery cell 110. The dimension of each battery cell 110 in the Y direction is the dimension in the thickness direction of each battery cell 110. The shape of each battery cell 110 is not limited to this example.

[0016] Each battery cell 110 includes a battery element (not shown), an exterior material 112, a positive electrode tab 114, and a negative electrode tab 116. In one example, the battery element includes a plurality of positive electrodes and a plurality of negative electrodes (not shown) stacked alternately in the Y direction, and a separator (not shown) positioned between adjacent positive electrodes and negative electrodes in the Y direction. The exterior material 112 seals the battery element and an electrolyte (not shown). The positive electrode tab 114 is electrically connected to the positive electrode of the battery element. The positive electrode tab 114 is pulled out from one of both sides of the exterior material 112 in the X direction. The negative electrode tab 116 is electrically connected to the negative electrode of the battery element. The negative electrode tab 116 is pulled out from the other side of both sides of the exterior material 112 in the X direction. However, the structure of each battery cell 110 is not limited to this example.

[0017] Each battery cell 110 may be an all-solid-state battery. In an all-solid-state battery, a solid electrolyte layer is provided in a portion corresponding to a separator. An all-solid-state battery does not contain an electrolyte solution. Unless otherwise specified, the following description will be given assuming that each battery cell 110 is a battery cell containing an electrolyte solution.

[0018] The multiple battery cells 110 are electrically connected in a series-parallel combination. Specifically, cell groups including at least two battery cells 110 adjacent to each other in the Y direction and connected in parallel are stacked in the Y direction and connected in series. On the +X side of the stack of battery cells 110, a positive electrode tab 114 drawn from a battery cell 110 of one cell group connected in parallel and a negative electrode tab 116 drawn from a battery cell 110 of another cell group connected in parallel are electrically connected to each other, forming a tab group 118 including the positive electrode tab 114 and the negative electrode tab 116. The positive electrode tab 114 and the negative electrode tab 116 in the tab group 118 are joined to each other by, for example, laser welding. A tab group 118 is also located on the −X side of the stack of battery cells 110. Thus, multiple cell groups are connected in series from the cell group located at one end of the stack of battery cells 110 in the Y direction to the cell group located at the other end of the stack of battery cells 110 in the Y direction. Hereinafter, as necessary, the tab group 118 located on the +X side of the stack of battery cells 110 will be referred to as the +X side tab group 118, and the tab group 118 located on the -X side of the stack of battery cells 110 will be referred to as the -X side tab group 118.

[0019] The electrical connection of the plurality of battery cells 110 is not limited to the above example. For example, a stack of battery cells 110 may be configured by connecting single battery cells 110 in series.

[0020] The first voltage detection device 130 detects the voltages of the plurality of +X side tab groups 118. The first voltage detection device 130 includes a first protector 131, a plurality of first voltage detection terminals 132, a plurality of first voltage detection lines 133, a first connector 134, and a first bus bar 135.

[0021] The first protector 131 covers the +X side portion of the stack of battery cells 110. The first protector 131 is, for example, an insulator such as resin. The first protector 131 defines a plurality of first openings 131a. Each of the plurality of +X side tab groups 118 is exposed toward the +X side through each of the plurality of first openings 131a.

[0022] Each of the multiple first voltage detection terminals 132 is located on the +X side of each of the multiple +X side tab groups 118. Each first voltage detection terminal 132 is made of a conductive material such as metal. The -X side surface of each first voltage detection terminal 132 and the +X side surface of each +X side tab group 118 are joined to each other by a joining method such as laser welding. Therefore, each first voltage detection terminal 132 and each +X side tab group 118 are electrically connected to each other. Therefore, the first voltage detection device 130 can detect the voltage of each +X side tab group 118 using each first voltage detection terminal 132. The multiple first voltage detection terminals 132 are held together by a first protector 131. Therefore, by placing the first protector 131 at an appropriate position relative to the stack of battery cells 110, each of the multiple first voltage detection terminals 132 can be positioned appropriately relative to each of the multiple +X side tab groups 118.

[0023] One end of each first voltage detection line 133 is electrically connected to each first voltage detection terminal 132. The other end of each first voltage detection line 133 is electrically connected to each first connector 134. Thus, the first voltage detection terminals 132 and the first connectors 134 are electrically connected to each other via the first voltage detection lines 133. Each first voltage detection line 133 is routed between one end of the first voltage detection line 133 and the other end of the first voltage detection line 133 via the first protector 131.

[0024] The first bus bar 135 is disposed at the end portion on the +Y side of the first protector 131. The first bus bar 135 is electrically connected to the positive electrode tab 114 drawn out to the +X side from the battery cell 110 of the cell group located at the end portion on the +Y side of the stack of battery cells 110. The first bus bar 135 functions as an external terminal for electrically connecting the battery module 100 to an external device such as another battery module.

[0025] The second voltage detection device 140 detects the voltages of the plurality of −X side tab groups 118. The second voltage detection device 140 has a second protector 141, a plurality of second voltage detection terminals 142, a plurality of second voltage detection lines 143, a second connector 144, and a second bus bar 145.

[0026] The second protector 141 covers the -X side portion of the stack of battery cells 110. The second protector 141 is, for example, an insulator such as resin. The second protector 141 defines a plurality of second openings 141a. Each of the plurality of -X side tab groups 118 is exposed toward the -X side through each of the plurality of second openings 141a.

[0027] Each of the multiple second voltage detection terminals 142 is located on the -X side of each of the multiple -X side tab groups 118. Each second voltage detection terminal 142 is made of a conductive material such as metal. The +X side surface of each second voltage detection terminal 142 and the -X side surface of each -X side tab group 118 are joined to each other by a joining method such as laser welding. Therefore, each second voltage detection terminal 142 and each -X side tab group 118 are electrically connected to each other. Therefore, the second voltage detection device 140 can detect the voltage of each -X side tab group 118 using each second voltage detection terminal 142. The multiple second voltage detection terminals 142 are held together by a second protector 141. Therefore, by placing the second protector 141 at an appropriate position relative to the stack of battery cells 110, each of the multiple second voltage detection terminals 142 can be positioned appropriately relative to each of the multiple -X side tab groups 118.

[0028] One end of each second voltage detection line 143 is electrically connected to each second voltage detection terminal 142. The other end of each second voltage detection line 143 is electrically connected to each second connector 144. Thus, the second voltage detection terminals 142 and the second connector 144 are electrically connected to each other via the second voltage detection lines 143. Each second voltage detection line 143 is routed between one end of the second voltage detection line 143 and the other end of the second voltage detection line 143 via the second protector 141.

[0029] The second bus bar 145 is disposed at the end portion on the -Y side of the second protector 141. The second bus bar 145 is electrically connected to the negative electrode tab 116 that is drawn out to the -X side from the battery cell 110 of the cell group located at the end portion on the -Y side of the stack of battery cells 110. The second bus bar 145 functions as an external terminal for electrically connecting the battery module 100 to an external device such as another battery module.

[0030] 1 , the positive electrode tab 114 at the end of a group of multiple cells connected in series is drawn out toward the +X side from the battery cell 110 of the cell group located at the end portion on the +Y side of the stack of battery cells 110, and the negative electrode tab 116 at the end of a group of multiple cells connected in series is drawn out toward the −X side from the battery cell 110 of the cell group located at the end portion on the −Y side of the stack of battery cells 110. Thus, the first bus bar 135 is disposed on the +X side and +Y side of the stack of battery cells 110, and the second bus bar 145 is disposed on the −X side and −Y side of the stack of battery cells 110. However, the arrangement of the positive electrode tab 114 and the negative electrode tab 116 at the end of a group of multiple cells connected in series may differ depending on the number of battery cells 110 included in the stack of battery cells 110. For example, there may be a case where the positive electrode tab 114 at the end of a group of multiple cells connected in series is pulled out toward the +X side from the battery cell 110 of the cell group located at the end portion on the +Y side of the stack of battery cells 110, and the negative electrode tab 116 at the end of a group of multiple cells connected in series is pulled out toward the +X side from the battery cell 110 of the cell group located at the end portion on the −Y side of the stack of battery cells 110. In this case, the first bus bar 135 is arranged on the +X side and the +Y side of the stack of battery cells 110, and the second bus bar 145 is arranged on the +X side and the −Y side of the stack of battery cells 110.

[0031] The housing 200 houses a stack of battery cells 110. The housing 200 has a first plate 210, a second plate 220, a third plate 230, a fourth plate 240, a fifth plate 250, and a sixth plate 260. Each plate is, for example, a metal plate.

[0032] The first plate 210 covers the +X side portion of the stack of battery cells 110, with the first voltage detection device 130 located between the stack of battery cells 110 and the first plate 210. The second plate 220 covers the −X side portion of the stack of battery cells 110, with the second voltage detection device 140 located between the stack of battery cells 110 and the second plate 220. The third plate 230 covers the +Y side portion of the stack of battery cells 110. The fourth plate 240 covers the −Y side portion of the stack of battery cells 110. The fifth plate 250 covers the +Z side portion of the stack of battery cells 110, with multiple structural adhesives 310 located between the stack of battery cells 110 and the fifth plate 250. In the example shown in FIG. 1 , the multiple structural adhesives 310 extend in the Y direction. The arrangement of the structural adhesives 310 is not limited to the example shown in FIG. 1 . The stack of battery cells 110 and the fifth plate 250 are bonded to each other via a plurality of structural adhesives 310. The sixth plate 260 covers a portion of the −Z side of the stack of battery cells 110, with a thermally conductive adhesive 320 positioned between the stack of battery cells 110 and the sixth plate 260. The stack of battery cells 110 and the sixth plate 260 are bonded to each other via the thermally conductive adhesive 320. The stack of battery cells 110 and the sixth plate 260 are thermally coupled to each other via the thermally conductive adhesive 320.

[0033] 2 is a top view of a fifth plate 250 according to the embodiment. In FIG. 2, a white circle with a black dot indicating the Z direction indicates that the tip of the arrow indicating the Z direction is facing towards the front of the paper.

[0034] The housing 200 will be described with reference to FIGS.

[0035] As shown in Fig. 1 , when viewed from the X direction, the first plate 210 and the second plate 220 have a substantially rectangular shape with a pair of long sides parallel to the Y direction and a pair of short sides parallel to the Z direction. As shown in Fig. 1 , when viewed from the Y direction, the third plate 230 and the fourth plate 240 have a substantially rectangular shape with a pair of long sides parallel to the X direction and a pair of short sides parallel to the Z direction. As shown in Fig. 1 and 2 , when viewed from the Z direction, the fifth plate 250 and the sixth plate 260 have a substantially square or rectangular shape with a pair of sides parallel to the X direction and another pair of sides parallel to the Y direction.

[0036] As shown in FIGS. 1 and 2 , the +Y side edge of the fifth plate 250 and the +Z side edge of the third plate 230 are joined to each other via a first laser weld 272, with the +Y side edge of the fifth plate 250 positioned on the +Z side of the +Z side edge of the third plate 230. The first laser weld 272 is formed by laser welding using a laser beam irradiated from the +Z side onto the +Y side edge of the fifth plate 250. The first laser weld 272 has a bead formed on the +Z side surface of the +Y side edge of the fifth plate 250. The laser welding is, for example, wobbling laser welding. In wobbling laser welding, the laser beam moves by combining a linear motion parallel to the X direction and a wobbling motion in a direction intersecting the X direction. The laser welding does not have to be wobbling laser welding. For example, the laser beam may move parallel to the X direction without including a wobbling motion.

[0037] As shown in FIG. 2 , when viewed from the Z direction, the first laser weld 272 extends intermittently in the X direction from one of the +X-side end and the −X-side end of the +Y-side edge of the fifth plate 250 to the other. In the example shown in FIG. 2 , when viewed from the Z direction, the first laser weld 272 is divided into multiple sections in the X direction. When viewed from the Z direction, these sections of the first laser weld 272 are located on the same line parallel to the X direction. However, the number and arrangement of the sections of the first laser weld 272 are not limited to the example shown in FIG. 2 . If the first laser weld 272 were to extend continuously from one of the +X-side end and the −X-side end of the +Y-side edge of the fifth plate 250 to the other, it may be difficult to suppress welding defects in the first laser weld 272 due to distortion of the components themselves, including the fifth plate 250 and the third plate 230, or distortion due to expansion or contraction of the components caused by heat generated by laser welding. However, in the embodiment, the first laser weld 272 is divided into a plurality of sections in the X direction. Therefore, compared to a case where the first laser weld 272 extends continuously from one end on the +X side to the other end on the −X side of the +Y side of the fifth plate 250, the above-mentioned strain can be more easily released between the divided sections of the first laser weld 272, and welding defects of the first laser weld 272 can be suppressed.

[0038] As shown in Fig. 2, the +Y side edge of the fifth plate 250 has a plurality of first notches 252 at a plurality of locations. In the example shown in Fig. 2, the plurality of first notches 252 are arranged at approximately equal intervals in the X direction. The number and arrangement of the first notches 252 are not limited to the example shown in Fig. 2. As shown in Fig. 2, the first laser weld 272 is interrupted at the location of the first notch 252 on the +Y side edge of the fifth plate 250. Specifically, in the laser welding to form the first laser weld 272, the laser beam is not irradiated to the periphery of the first notch 252 in the X direction.

[0039] When the first notches 252 are provided, the above-described strain can be more easily released toward the first notches 252 than when the first notches 252 are not provided, thereby suppressing welding defects at the first laser welds 272. In the example shown in FIG. 2 , first notches 252 are provided not only between the divided first laser welds 272 but also on the +X side of the end furthest on the +X side of the first laser welds 272, and first notches 252 are also provided on the −X side of the end furthest on the −X side of the first laser welds 272. Therefore, compared to when these first notches 252 are not provided, the above-described strain can be more easily released toward the first notches 252, thereby suppressing welding defects at the first laser welds 272.

[0040] Each first notch 252 is located on the +Z side of the +Z side edge of the third plate 230. Therefore, the +Y side edge of the fifth plate 250 and the +Z side edge of the third plate 230 can be welded to each other with the portion of the +Z side edge of the third plate 230 located on the -Z side of each first notch 252 exposed toward the +Z side through each first notch 252. Therefore, when welding the +Y side edge of the fifth plate 250 and the +Z side edge of the third plate 230, the Z-direction distance between the +Z side surface of the fifth plate 250 and the +Z side edge of the third plate 230 can be measured from the +Z side of the fifth plate 250. From the measured distance and the Z-direction thickness of the fifth plate 250, the gap between the +Y side edge of the fifth plate 250 and the +Z side edge of the third plate 230 can be calculated. Therefore, it is possible to determine from the calculated gap whether the +Y side edge of fifth plate 250 and the +Z side edge of third plate 230 can be welded. Specifically, if the calculated gap is equal to or less than a predetermined value, it is possible to determine that the +Y side edge of fifth plate 250 and the +Z side edge of third plate 230 can be welded. By determining from the calculated gap whether the +Y side edge of fifth plate 250 and the +Z side edge of third plate 230 can be welded, it is possible to prevent poor welding of first laser welded portion 272.

[0041] In the example shown in FIG. 2 , the first notches 252 can divide the first laser welds 272 into sections at appropriate intervals in the X direction. The shorter the X direction dimension of the first laser welds 272 divided by the first notches 252, the less the effect of the above-described distortion of the first laser welds 272 in the sections divided by the first notches 252 can be. For example, if distortion of 1% of the X direction dimension of the first laser welds 272 occurs, the distortion will be 0.5 cm when the X direction dimension of the first laser welds 272 is 50 cm, but the distortion will be 0.2 cm when the X direction dimension of the first laser welds 272 is 20 cm. Therefore, by dividing the first laser welds 272 into sections at appropriate intervals in the X direction by the first notches 252, welding defects of the first laser welds 272 can be suppressed.

[0042] A through-hole may be provided on the +Y side edge of the fifth plate 250 instead of or in addition to the first notch 252. By providing a cutout portion such as a notch or a through-hole on the +Y side edge of the fifth plate 250, welding defects at the first laser weld 272 can be suppressed for the same reasons as those described for the first notch 252.

[0043] The −Y side edge of the fifth plate 250 is provided with second laser welds 274 and a plurality of second notches 254, similar to the +Y side edge of the fifth plate 250. The second laser welds 274 and the plurality of second notches 254 correspond to the first laser welds 272 and the plurality of first notches 252, respectively. The −Y side edge of the fifth plate 250 and the +Z side edge of the fourth plate 240 are joined to each other via the second laser welds 274. The second laser welds 274 and the plurality of second notches 254 may be similar to the first laser welds 272 and the plurality of first notches 252, respectively, except that the first laser welds 272 and the second laser welds 274 are arranged substantially symmetrically, and the plurality of first notches 252 and the plurality of second notches 254 are arranged substantially symmetrically.

[0044] 2 can also be applied to other parts of the housing 200. For example, the laser welding described using Fig. 2 can also be applied to laser welding the +Y side edge of the sixth plate 260 and the -Z side edge of the third plate 230, or to laser welding the -Y side edge of the sixth plate 260 and the -Z side edge of the fourth plate 240.

[0045] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted.

[0046] This application claims priority based on Japanese Patent Application No. 2024-033969, filed March 6, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0047] REFERENCE SIGNS LIST 100 Battery module, 110 Battery cell, 112 Exterior material, 114 Positive electrode tab, 116 Negative electrode tab, 118 Tab group, 120 Compression pad, 130 First voltage detection device, 131 First protector, 131a First opening, 132 First voltage detection terminal, 133 First voltage detection line, 134 First connector, 135 First bus bar, 140 Second voltage detection device, 141 Second protector, 141a Second opening, 142 Second voltage detection terminal, 143 Second voltage detection line, 144 Second connector, 145 Second bus bar, 200 Housing, 210 First plate, 220 Second plate, 230 Third plate, 240 Fourth plate, 250 Fifth plate, 252 First notch, 254 Second notch, 260 Sixth plate, 272 First laser weld, 274 Second laser weld, 310 Structural adhesive, 320 Thermally conductive adhesive

Claims

1. A battery module comprising: battery cells; and a housing that houses the battery cells, wherein the housing has a plurality of members joined to one another via laser welds, and the laser welds extend intermittently.

2. The battery module according to claim 1, wherein the plurality of members have a cutout at at least one location, and the laser weld is interrupted at the at least one location.

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