Battery module

Abstract

Provided is a battery module (100) comprising: a stack (101) in which a plurality of battery cells (110) are stacked in the thickness direction; a housing body (200) (housing) that houses the stack (101); and a fixing layer (500) that fixes a surface (251) of the housing body (200) that faces a cell side surface (113) of the battery cell (110) and the cell side surface (113) of the battery cell (110). The fixing layer (500) covers 50% or more of a target surface (stack side surface (103)) corresponding to the cell side surface (113) of the battery cell (110) of the stack (101).

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 a plurality of battery cells stacked in a predetermined direction and a housing that houses the plurality of battery cells.

[0003] Patent Documents 1 and 2 describe a battery module. The battery module is a stack of multiple battery cells. Both the upper and lower surfaces of the stack are fixed to a housing that houses the stack with a thermally conductive adhesive.

[0004] Chinese Utility Model No. 215816165 Chinese Utility Model No. 213026370

[0005] In battery modules, gas is generated due to deterioration inside the battery, overcharging, and over-discharging, and the generated gas needs to be properly released to the outside.

[0006] An example of an object of the present invention is to provide a technique for appropriately releasing gas generated inside a battery module to the outside.

[0007] The present invention provides the following technologies: 1. A battery module comprising: a stack in which a plurality of battery cells are stacked in the thickness direction; a housing that houses the stack; and a fixing layer that fixes a surface of the housing that faces a side surface of the battery cell to the side surface of the battery cell, the fixing layer covering 50% or more of a target surface of the stack that corresponds to the side surface of the battery cell. 2. The battery module described in 1., in which a plurality of the fixing layers are provided. 3. The battery module described in 1. or 2., in which at least one of the plurality of fixing layers extends in a direction intersecting all of the cells. 4. The battery module described in 1. or 2., in which the width of the gap between adjacent fixing layers is 0.2 to 5 times the width of the fixing layer.

[0008] According to the above aspect of the present invention, it is possible to provide a technique for appropriately releasing gas generated inside a battery module to the outside.

[0009] Fig. 1 is an exploded perspective view from above of a battery module according to a first embodiment; Fig. 2 is a view focusing on the cell side surfaces of adjacent battery cells according to the first embodiment; Fig. 3 is a view illustrating an example of the arrangement of fixing layers provided on the upper surface of a stack according to the first embodiment; Fig. 4 is a view illustrating an example of the arrangement of fixing layers provided on the upper surface of a stack according to a second embodiment; Fig. 5 is a view illustrating an example of the arrangement of fixing layers provided on the upper surface of a stack according to a third embodiment;

[0010] 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.

[0011] First Embodiment Overview of Battery Module Fig. 1 is an exploded perspective view of a top of a battery module 100 according to an embodiment. Fig. 2 is an enlarged view of a cell side surface 113 of a battery cell.

[0012] 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.

[0013] 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 , a container 200 , an adhesive 300 , and a fixing layer 500 .

[0014] <Stack> A plurality of battery cells 110 and a plurality of compression pads 120 are stacked alternately in the Y direction. Each compression pad 120 is disposed between adjacent battery cells 110 in the Y direction and on both sides of the plurality of battery cells 110 in the Y direction. Hereinafter, a plurality of battery cells 110 and a plurality of compression pads 120 stacked alternately in the Y direction will be referred to as a stack 101 of battery cells 110. The stack 101 as a whole is a rectangular parallelepiped. Here, the term "rectangular parallelepiped" does not refer only to a perfect rectangular parallelepiped, but also to the presence of unevenness, curved surfaces, and the like due to the shapes of the battery cells 110, compression pads 120, and the like that constitute the stack 101. In this embodiment, the +Z side surface of the stack 101 will be referred to as the stack side surface 103.

[0015] <Battery Cell> The battery cell 110 has a thin rectangular parallelepiped shape with a rectangular surface (main surface) when viewed from the Y direction. Here, "rectangle" does not mean a perfect rectangle, but rather allows for unevenness, curved surfaces, etc. on each side of the rectangle. "Rectangular" does not only mean a perfect rectangular parallelepiped, but also allows for unevenness, curved surfaces, etc. on each face and edge of the rectangular parallelepiped. The X-direction dimension of each battery cell 110 is the longitudinal dimension of each battery cell 110. The Z-direction dimension of each battery cell 110 is the lateral dimension of each battery cell 110. The Y-direction dimension of each battery cell 110 is the thickness dimension of each battery cell 110. The shape of each battery cell 110 is not limited to this example. In this embodiment, the surface visible from the +Z side of the battery cell 110 is referred to as the cell side surface 113. The stack side surface 103 described above can also be considered a surface formed by an assembly of cell side surfaces 113. In other words, in the laminate 101, the target surface corresponding to the cell side surface 113 of the battery cell 110 is the laminate side surface 103. In other words, the target surface (laminate side surface 103) refers, for example, to the area surrounded by a line connecting the outermost contours in a top view (more specifically, an image when the laminate side surface 103 is projected in the Z direction).

[0016] The battery cell 110 includes a cell body 111, a positive electrode tab 114, and a negative electrode tab 116. In one example, the cell body 111 is a battery element and includes multiple positive electrodes and multiple 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 cell body 111 includes an exterior material 112. The exterior material 112 seals an electrolyte (not shown). A sealing edge 119 is provided on the side of the exterior material 112, extending from the cell body 111 as a sealing structure (so-called sealing margin). For example, FIG. 2 shows the sealing edge 119 on the +Z side. The sealing edge 119 on the +Z side is bent so as to be parallel to the stack side surface 103. In other words, at least a portion of the sealing edge 119 is included in the stack side surface 103. The bending directions of the sealing edges 119 may be the same direction or may be alternately different directions (+Y direction, −Y direction). 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 the two 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 one of the two 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 plurality of battery cells 110 are electrically connected in a combination of series and parallel connections. Specifically, cell groups each 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.

[0019] On the +X side of the stack 101 of battery cells 110, a positive electrode tab 114 drawn out from a battery cell 110 of one cell group connected in parallel and a negative electrode tab 116 drawn out 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.

[0020] The positive electrode tabs 114 and the negative electrode tabs 116 in the tab group 118 are joined to each other by, for example, laser welding. A tab group 118 is similarly located on the −X side of the stack 101 of battery cells 110. Therefore, a plurality of cell groups are connected in series from the cell group located on one end side of the stack 101 of battery cells 110 in the Y direction to the cell group located on the other end side of the stack 101 of battery cells 110 in the Y direction. Hereinafter, as necessary, the tab group 118 located on the +X side of the stack 101 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 101 of battery cells 110 will be referred to as the −X-side tab group 118.

[0021] The electrical connection of the plurality of battery cells 110 is not limited to the above example. For example, the stack 101 of battery cells 110 may be configured by connecting single battery cells 110 in series.

[0022] <First Voltage Detecting Device> The first voltage detecting device 130 detects the voltages of the multiple +X side tab groups 118. The first voltage detecting device 130 has a first protector 131, multiple first voltage detecting terminals 132, multiple first voltage detecting lines 133, a first connector 134, and a first bus bar 135.

[0023] The first protector 131 covers the +X side portion of the stack 101 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.

[0024] 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 101 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.

[0025] 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.

[0026] 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 101 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.

[0027] <Second Voltage Detecting Device> The second voltage detecting device 140 detects the voltages of the multiple -X side tab groups 118. The second voltage detecting device 140 has a second protector 141, multiple second voltage detecting terminals 142, multiple second voltage detecting lines 143, a second connector 144, and a second bus bar 145.

[0028] The second protector 141 covers the -X side portion of the stack 101 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.

[0029] 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 101 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.

[0030] 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.

[0031] 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 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 101 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.

[0032] 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 101 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 101 of battery cells 110. Thus, the first bus bar 135 is arranged on the +X side and +Y side of the stack 101 of battery cells 110, and the second bus bar 145 is arranged on the −X side and −Y side of the stack 101 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 101 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 101 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 101 of battery cells 110. In this case, the first bus bar 135 is arranged on the +X side and +Y side of the stack 101 of battery cells 110, and the second bus bar 145 is arranged on the -X side and -Y side of the stack 101 of battery cells 110.

[0033] <Housing (Case)> 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 .

[0034] The first plate 210 is a metal plate such as an aluminum plate, and covers the +X side portion of the stack 101 of battery cells 110 and the +X side portion of the first voltage detection device 130. The first plate 210 is provided with a plurality of gas release portions 155 that penetrate the first plate 210 in the thickness direction and communicate between the inside and outside of the housing 200. The shape of the gas release portions 155 is, for example, circular when viewed from the +X side. The shape of the gas release portions 155 is not limited to circular, and various shapes can be used as long as they have a gas release function. Furthermore, the shapes and sizes of all the gas release portions 155 may be the same or different.

[0035] The second plate 220 is a metal plate such as an aluminum plate, and covers the -X side portion of the stack 101 of battery cells 110 and the -X side portion of the second voltage detection device 140. The second plate 220 is provided with a plurality of gas release portions 255 that penetrate the second plate 220 in the thickness direction and communicate between the inside and outside of the housing 200. The shape of the gas release portions 255 is, for example, circular when viewed from the -X side. The shape of the gas release portions 255 is not limited to circular, and various shapes can be used as long as they have a gas release function. The shapes and sizes of all the gas release portions 255 may be the same or different.

[0036] The third plate 230 is, for example, a metal plate such as an aluminum plate, and covers the +Y side portion of the stack 101 of battery cells 110 .

[0037] The fourth plate 240 is, for example, a metal plate such as an aluminum plate, and covers the −Y side portion of the stack 101 of battery cells 110 .

[0038] The fifth plate 250 is, for example, a metal plate such as an aluminum plate, and covers the +Z side portion of the stack 101 of the battery cells 110 (i.e., the stack side surface 103).

[0039] The sixth plate 260 is, for example, a metal plate such as an aluminum plate, and covers the −Z side portion of the stack 101 of battery cells 110 .

[0040] <Overview of the upper and lower fixing structure for the stack (battery cells)>

[0041] In the laminate 101, the portion on the -Z side is fixed to the sixth plate 260 by adhesive 300, and the portion on the +Z side, i.e., the laminate side surface 103, is fixed to the fifth plate 250 by a fixing layer 500.

[0042] The adhesive 300 has thermal conductivity. The adhesive 300 is, for example, a thermally conductive adhesive such as a silicone adhesive or a urethane adhesive. The adhesive 300 is at least partially located between the −Z side surface of the stack 101 of battery cells 110 and the +Z side surface of the sixth plate 260 in the Z direction. Therefore, heat generated from the stack 101 of battery cells 110 can be released toward the sixth plate 260 via the adhesive 300. However, the adhesive 300 does not have to have thermal conductivity.

[0043] The fixing layer 500 is a thermally conductive adhesive such as a silicone adhesive or a urethane adhesive. The fixing layer 500 is partially located in the Z direction between the +Z side surface (stack side surface 103) of the stack 101 of battery cells 110 and the −Z side surface (i.e., the inner surface of the housing 200) of the fifth plate 250. This structure allows heat generated from the stack 101 of battery cells 110 to escape toward the fifth plate 250 via the fixing layer 500. However, the fixing layer 500 does not necessarily have thermal conductivity. Hereinafter, the adhesive 300 and the fixing layer 500 are formed by curing an adhesive in a liquid or gel state before curing (hereinafter referred to as uncured adhesive). The specific shape, arrangement, etc. of the fixing layer 500 will be described later.

[0044] A method for fixing the stack 101 to the housing 200 will be described. In this embodiment, a first step is performed in which the stack 101 is fixed to a sixth plate 260, which will be the bottom surface of the housing 200, using adhesive 300. Next, a second step is performed in which the first plate 210, the second plate 220, the third plate 230, and the fourth plate 240 are bonded around the periphery of the sixth plate 260. Furthermore, a third step is performed in which a fifth plate 250, which will be the lid of the housing 200, is fixed to the top surface (stack side surface 103) of the stack 101 using a fixing layer 500.

[0045] The first step will be described. Uncured adhesive is applied to the +Z side surface of the sixth plate 260. Next, the stack 101 of battery cells 110 is placed on the +Z side surface of the sixth plate 260 via the uncured adhesive. Next, the uncured adhesive is cured to change the uncured adhesive into adhesive 300. There are no particular limitations on the method for curing the uncured adhesive, and examples include drying, heating, and light irradiation. As a result, the stack 101 is fixed to the sixth plate 260.

[0046] The second step will be described. After the laminate 101 is fixed to the +Z side surface of the sixth plate 260 with the adhesive 300, the first plate 210, the second plate 220, the third plate 230, and the fourth plate 240 are joined around the periphery of the sixth plate 260. Specifically, the -Z side end of the first plate 210 and the +X side end of the sixth plate 260 are joined to each other by a joining method such as laser welding, and the -Z side end of the second plate 220 and the -X side end of the sixth plate 260 are joined to each other by a joining method such as laser welding. Furthermore, the -Z side end of the third plate 230 and the +Y side end of the sixth plate 260 are joined to each other by a joining method such as laser welding, and the -Z side end of the fourth plate 240 and the -Y side end of the sixth plate 260 are joined to each other by a joining method such as laser welding.

[0047] The third step will now be described. Uncured adhesive is applied to the +Z side surface of the fifth plate 250 (i.e., the inner surface of the housing 200). Next, the -Z side surface of the fifth plate 250 to which the uncured adhesive has been applied is placed on the stack side surface 103 of the stack 101 of battery cells 110. Next, the uncured adhesive is cured to form the fixing layer 500. The method for curing the uncured adhesive is not particularly limited, and examples include drying, heating, and light irradiation. As a result, the stack side surface 103 of the stack 101 is fixed to the fifth plate 250.

[0048] The method of fixing the stack 101 to the container 200 is not limited to the above method, and other methods may also be employed. Another method will be briefly described below.

[0049] First, the voltage detection devices (first voltage detection device 130, second voltage detection device 140) and the first to fourth plates 210 to 240 are arranged on the laminate 101, and adjacent plates are joined by laser welding. As a result, the side portions of the laminate 101 are covered by the voltage detection devices (first voltage detection device 130, second voltage detection device 140) and the first to fourth plates 210 to 240.

[0050] Next, the sixth plate 260, which will form the bottom surface, is joined by laser welding to the member to which the voltage detection devices (first voltage detection device 130, second voltage detection device 140) and the first to fourth plates 210 to 240 are joined, and further, the sixth plate 260, which will form the lid, is joined by laser welding.

[0051] <Fixing Structure 1 on the Upper Side of the Stack (Battery Cell)> The fixing structure between the upper surface (stack body side surface 103) of the stack body 101 and the fifth plate 250 will be described in more detail with reference to Figure 3. Figure 3 is a diagram illustrating an example of the arrangement of a fixing layer 500 provided on the stack body side surface 103 of the stack body 101. The shape and arrangement of the fixing layer 500 can also be said to be the arrangement formed when uncured adhesive is applied to the -Z side surface of the fifth plate 250.

[0052] The multiple fixing layers 500 cover a surface formed as an aggregate of the cell side surfaces 113 of the battery cells 110 , that is, 50% or more of the stack side surface 103 of the stack 101 .

[0053] The lower limit of the proportion of the stack side surface 103 covered by the fixing layer 500 is preferably 60% or more, more preferably 70% or more. The upper limit is not particularly limited, but from the viewpoint of providing a gas layer 550 in the gap between the fixing layers 500, it is 95% or less, preferably 90% or less, and more preferably 85% or less. The gas layer 550 is connected to a release valve. The release valve is provided, for example, on the fifth plate 250 that contacts the gas layer 550. In other words, there is no region of the gas layer 550 that is surrounded by the fixing layer 500 in the X direction and the Y direction.

[0054] By making the area of ​​the fixing layer 500 50% or more, the area (gas layer 550) that accumulates gas generated from the battery cells 110 can be limited to a certain range. Note that if the area of ​​the fixing layer 500 exceeds 95%, the gas discharge area becomes too small, which can cause the internal pressure of the battery accommodating body 200 to become too high, or the rate of pressure increase can be too high, resulting in an excessively fast gas discharge rate. If the discharged high-temperature gas is exposed to another battery module 100, a chain reaction may occur in which the other battery module 100 becomes hot and generates gas inside. Therefore, it is necessary to control the gas discharge rate within an appropriate range. In this embodiment, the position and volume of the gas layer 550 where gas accumulates can be limited to a certain range, thereby controlling the gas discharge rate and discharge location. Furthermore, the gas layer 550 is connected to a release valve, and by ensuring that there is no area surrounded by the fixing layer 500 in the X and Y directions, the pressure inside the battery module 100 can be kept below a predetermined level.

[0055] A plurality of fixed layers 500 are provided. Here, first to eighth fixed layers 501 to 508 are arranged in order as the fixed layers 500 from the first plate 210 side (+X side) to the second plate 220 side (-X side). When there is no need to distinguish between the first to eighth fixed layers 501 to 508, they will be simply referred to as "fixed layers 500."

[0056] When viewed from the Z direction, each of the first to eighth fixed layers 501 to 508 has an elongated (or strip-like) shape with its longitudinal direction being the horizontal direction (Y direction) perpendicular to the extension direction of the cell side surface 113 (i.e., the X direction).

[0057] At least one of the multiple fixing layers 500 intersects with all of the battery cells 110. In this embodiment, the second to eighth fixing layers 502 to 508 intersect with all of the battery cells 110.

[0058] The first fixed layer 501 is composed of two parts, a first fixed layer (A) 501a on the +Y direction side and a first fixed layer (B) 501b. The first fixed layer (A) 501a and the first fixed layer (B) 501b are separated from each other at the middle position in the Y direction. The separated portion forms a gas layer 560. When there is no need to distinguish between the first fixed layer (A) 501a and the first fixed layer (B) 501b, they will be simply referred to as the "first fixed layer 501."

[0059] The first to fourth fixed layers 501 to 504 are integrated such that adjacent longitudinal edges of each component coincide with each other in a top view. "Coinciding" means that there is substantially no gas layer 550 between adjacent fixed layers 500. Therefore, the portions where adjacent fixed layers 500 coincide do not need to be flush with each other. Specifically, the -X side edge of the first fixed layer 501 and the +X side edge of the second fixed layer 502 are in contact. The -X side edge of the second fixed layer 502 and the +X side edge of the third fixed layer 503 are in contact. The -X side edge of the third fixed layer 503 and the +X side edge of the fourth fixed layer 504 are in contact.

[0060] The fifth to eighth fixed layers 505 to 508 are integrated such that adjacent longitudinal sides of each component coincide when viewed from above. Specifically, the −X side of fifth fixed layer 505 contacts the +X side of sixth fixed layer 506. The −X side of sixth fixed layer 506 contacts the +X side of seventh fixed layer 507. The −X side of seventh fixed layer 507 contacts the +X side of eighth fixed layer 508.

[0061] The fourth fixing layer 504 and the fifth fixing layer 505 are spaced apart, and the gap between them forms a gas layer 550. Gas generated in the battery cell 110 accumulates in the gas layer 550.

[0062] <Gas flow> The gas generated in the battery cells 110 passes through the gaps inside the stack 101, i.e., the gaps formed between the battery cells 110 and the compression pads 120, and is released to the outside from the gas release section 155 of the first plate 210 and the gas release section 155 of the second plate 220.

[0063] Furthermore, some of the gas generated in the battery cell 110 temporarily accumulates in a gas layer 550 between the fourth fixing layer 504 and the fifth fixing layer 505. The gas then passes through gaps inside the stack 101 and is gradually released to the outside from the gas release portions 155, 255. Note that a gas release portion such as a release valve may be provided in the fifth plate 250 at a position corresponding to the position where the gas layer 550 is provided. When the pressure becomes too high due to excess gas, the gas can be released from the release valve, and the pressure in the gas layer 550 can be controlled within an appropriate range.

[0064] The gas layer 550 functions as a buffer that temporarily stores gas. Therefore, even if a large amount of gas is generated due to deterioration, over-discharge, or over-charge of the battery cell 110, a sudden increase in pressure inside the housing 200 and a sudden increase in the rate at which the gas is discharged can be suppressed. As a result, even if the gas becomes excessively hot and a symptom of overheating and damage to a battery cell 110 occurs, the time until the symptom spreads to another battery cell 110 can be extended. For example, even if a malfunction such as a fire occurs in a vehicle equipped with the battery module 100, the time from the occurrence of the malfunction to the fire can be sufficiently extended, thereby ensuring sufficient time (e.g., the time required by law, etc.) for vehicle occupants to evacuate.

[0065] Second Embodiment A second embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram illustrating an example of the arrangement of a fixed layer 500 provided on the upper surface of the stack 101 of this embodiment. In this embodiment, adjacent fixed layers 500 are spaced apart. That is, a gas layer 550 is provided between adjacent fixed layers 500.

[0066] Specifically, first to sixth fixing layers 501 to 506 are provided as fixing layer 500. The area of ​​stack side surface 103 covered by first to sixth fixing layers 501 to 506 is 50% or more of the entire area of ​​stack side surface 103.

[0067] When viewed from the Z direction, each of the first to sixth fixed layers 501 to 506 has an elongated (or strip-like) shape with its longitudinal direction being the horizontal direction (Y direction) perpendicular to the extension direction of cell side surface 113 (i.e., the X direction). In this embodiment, the first and sixth fixed layers 501 and 506 are the thinnest, the second and fifth fixed layers 502 and 505 are the thickest, and the third and fourth fixed layers 503 and 504 are of intermediate thickness. The first to sixth fixed layers 501 to 506 are shaped and arranged to be roughly symmetrical front to back (left to right in FIG. 4 ) with respect to the center in the X direction.

[0068] The first fixed layer 501 is composed of two parts: a first fixed layer (A) 501a on the +Y direction side and a first fixed layer (B) 501b on the -Y direction side. The first fixed layer (A) 501a and the first fixed layer (B) 501b are separated at the middle position in the Y direction. The separated portion forms a gas layer 560. When there is no need to distinguish between the first fixed layer (A) 501a and the first fixed layer (B) 501b, they will be simply referred to as the "first fixed layer 501."

[0069] Among the first to sixth fixed layers 501 to 506, adjacent fixed layers 500 in the X direction are spaced apart to form gas layer 550. Specifically, first fixed layer 501 and second fixed layer 502 are spaced apart in the X direction. The gap between first fixed layer 501 and second fixed layer 502 forms first gas layer 551. Second fixed layer 502 and third fixed layer 503 are spaced apart in the X direction. The gap between second fixed layer 502 and third fixed layer 503 forms second gas layer 552. Third fixed layer 503 and fourth fixed layer 504 are spaced apart in the X direction. The gap between third fixed layer 503 and fourth fixed layer 504 forms third gas layer 553. Fourth fixed layer 504 and fifth fixed layer 505 are spaced apart in the X direction. The gap between fourth fixed layer 504 and fifth fixed layer 505 forms fourth gas layer 554. The fifth fixed layer 505 and the sixth fixed layer 506 are spaced apart in the X direction. The gap between the fifth fixed layer 505 and the sixth fixed layer 506 forms a fifth gas layer 555.

[0070] When the first to fifth gas layers 551 to 555 are not to be distinguished from one another, they will be simply referred to as "gas layers 550." In this embodiment, the first to fifth gas layers 551 to 555 have the same width (length in the +X direction). However, the widths of the first to fifth gas layers 551 to 555 are not limited to being the same.

[0071] The width of the gap between adjacent fixed layers 500 (i.e., the gas layer 550 ) is 0.2 to 5 times the width of the fixed layer 500 .

[0072] In this embodiment, the width of the gas layer 550 is 0.2 times the width of the widest fixed layer 500 among the multiple fixed layers 500 (the second fixed layer 502, the fourth fixed layer 504), and is 5 times the width of the narrowest fixed layer 500 among the multiple fixed layers 500 (the first fixed layer 501, the sixth fixed layer 506).

[0073] By setting the relationship between the width of the gas layer 550 and the width of the fixed layer 500 within the above range, it is possible to store a sufficient amount of gas in the gas layer 550, while suppressing the speed at which the gas moves outward (in the +X direction or the −X direction) through the gas layer 550 to an appropriate level. In other words, it is possible to appropriately adjust the gas movement speed.

[0074] Third Embodiment A third embodiment will be described with reference to Fig. 5. Fig. 5 is a diagram illustrating an example of the arrangement of a fixed layer 500 provided on the upper surface of the stack 101 of this embodiment. In this embodiment, adjacent fixed layers 500 are spaced apart. That is, a gas layer 550 is provided between adjacent fixed layers 500.

[0075] Specifically, first to fourth fixing layers 501 to 504 are provided as fixing layer 500. The area of ​​stack side surface 103 covered by first to fourth fixing layers 501 to 504 is 50% or more of the entire area of ​​stack side surface 103.

[0076] When viewed from the Z direction, each of the first to fourth fixed layers 501 to 504 has an elongated (or strip-like) shape with its longitudinal direction being the horizontal direction (Y direction) perpendicular to the extension direction (i.e., X direction) of cell side surface 113. In this embodiment, the first and fourth fixed layers 501 and 504 are the thinnest, the third fixed layer 503 is the thickest, and the second fixed layer 502 is of intermediate thickness.

[0077] The first fixed layer 501 is composed of two parts: a first fixed layer (A) 501a on the +Y direction side and a first fixed layer (B) 501b on the -Y direction side. The first fixed layer (A) 501a and the first fixed layer (B) 501b are separated at the middle position in the Y direction. The separated portion forms a gas layer 560. When there is no need to distinguish between the first fixed layer (A) 501a and the first fixed layer (B) 501b, they will be simply referred to as the "first fixed layer 501."

[0078] Adjacent fixed layers 500 of the first to fourth fixed layers 501 to 504 are spaced apart in the X direction, forming gas layers 550. Specifically, first fixed layer 501 and second fixed layer 502 are spaced apart in the X direction. The gap between first fixed layer 501 and second fixed layer 502 forms first gas layer 551. Second fixed layer 502 and third fixed layer 503 are spaced apart in the X direction. The gap between second fixed layer 502 and third fixed layer 503 forms second gas layer 552. Third fixed layer 503 and fourth fixed layer 504 are spaced apart in the X direction. The gap between third fixed layer 503 and fourth fixed layer 504 forms third gas layer 553. When there is no need to distinguish between first to third gas layers 551 to 553, they will be simply referred to as "gas layers 550." In this embodiment, the first and second gas layers 551, 552 have the same width (length in the +X direction). The width of the third gas layer 553, which is provided on the rearmost side (closest to the -X direction), is set to be much wider (about six times wider in this case) than the first and second gas layers 551, 552. The width of the third fixed layer 503 and the width of the third gas layer 553 are also approximately the same.

[0079] With this configuration, a large amount of gas can be stored in third gas layer 553. Furthermore, the width of third fixed layer 503 adjacent to third gas layer 553 on the +X side is set to be as wide as approximately 30% of the length of cell side surface 113 in the +X direction, so that gas in third gas layer 553 is less likely to move forward (in the +X direction) toward second gas layer 552.

[0080] 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.

[0081] Summary of the embodiment The features of the present embodiment can be summarized as follows. 1. A battery module 100 comprising: a stack 101 in which a plurality of battery cells 110 are stacked in the thickness direction; a housing 200 (housing) that houses the stack 101; and a fixing layer 500 that fixes a surface 251 of the housing 200 that faces the cell side surface 113 of the battery cell 110 and the cell side surface 113 of the battery cell 110, wherein the fixing layer 500 covers 50% or more of a target surface (stack side surface 103) of the stack 101 that corresponds to the cell side surface 113 of the battery cell 110. 2. The battery module 100 according to 1., in which a plurality of the fixing layers 500 are provided. 3. The battery module 100 according to 1. or 2, in which at least one of the plurality of fixing layers 500 extends in a direction intersecting all of the battery cells 110. 4. 3. The battery module 100 according to 1. or 2., wherein the width of the gap (gas layer 550) between adjacent fixing layers 500 is 0.2 to 5 times the width of the fixing layer 500.

[0082] This application claims priority based on Japanese Patent Application No. 2024-031045, filed March 1, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0083] 100 Battery module 101 Stacked body 103 Stacked body side surface 110 Battery cell 111 Cell body 113 Cell side surface 119 Sealing edge 120 Compression pad 130 First voltage detection device 140 Second voltage detection device 155, 255 Gas release portion 200 Housing 210 First plate 220 Second plate 230 Third plate 240 Fourth plate 250 Fifth plate 260 Sixth plate 300 Adhesive 500 Fixing layer 501 to 508 First to eighth fixing layers 550 Gas layers 551 to 555 First to fifth gas layers

Claims

1. A battery module comprising: a stack in which a plurality of battery cells are stacked in the thickness direction; a housing that houses the stack; and a fixing layer that fixes a surface of the housing that faces the side surface of the battery cell to the side surface of the battery cell, wherein the fixing layer covers 50% or more of a target surface of the stack that corresponds to the side surface of the battery cell.

2. The battery module according to claim 1, wherein a plurality of said fixing layers are provided.

3. The battery module according to claim 1 or 2, wherein at least one of the plurality of fixing layers extends in a direction intersecting all of the battery cells.

4. The battery module according to claim 1 or 2, wherein the width of the gap between adjacent fixing layers is 0.2 to 5 times the width of the fixing layer.

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