Battery module

Abstract

The present disclosure relates to a battery module. Provided are: a plurality of battery cells arranged along a predetermined first direction; a plurality of thermal insulation materials provided between the battery cells and in contact with adjacent battery cells; and a restriction member that applies a force to each battery cell in a direction in which each battery cell is in contact with the thermal insulation material, the thermal insulation material including a high-melting-point portion and a low-melting-point portion, the low-melting-point portion and the high-melting-point portion being arranged along a second direction orthogonal to the first direction, and the melting point of the low-melting-point portion being lower than that of the high-melting-point portion, in one of the two thermal insulation materials that sandwiches the battery cell from both sides in the first direction, the high-melting-point portion is located on one side in the second direction farther than the low-melting-point portion, and in the other of the two thermal insulation materials, the high-melting-point portion is located on the other side in the second direction farther than the low-melting-point portion.

Description

Technical Field

[0001] This invention relates to battery modules. Background Technology

[0002] Japanese Patent Application Publication No. 2023-524706 discloses a battery module comprising: a plurality of battery cells arranged along a predetermined direction; and a plurality of heat-insulating members disposed between adjacent battery cells and in contact with each battery cell. The exterior of each heat-insulating member is made of a material with a low melting point, and the interior of each heat-insulating member is made of a heat-resistant material with a higher melting point than the exterior. Summary of the Invention

[0003] When a battery cell experiences thermal runaway, the exterior of the two heat-insulating components on either side of the cell melts, and the heat-resistant material inside these components comes into contact with the battery cell. At this point, the contact area between the thermally runaway battery cell and the heat-resistant material on either side of the cell tends to increase. Therefore, heat from the thermally runaway battery cell can easily be transferred to other battery cells via the heat-resistant material on either side.

[0004] The present invention takes into account the above facts and aims to obtain a battery module that is difficult to transfer heat from a thermally runaway battery cell to other battery cells.

[0005] The battery module of the first type includes:

[0006] Multiple battery cells arranged along a predetermined first direction;

[0007] A plurality of heat-insulating materials disposed between adjacent battery cells and in contact with each battery cell; and

[0008] A constraint component that applies a force in a direction that brings each of the battery cells into contact with the heat-insulating material.

[0009] The heat-insulating material includes a high-melting-point portion and a low-melting-point portion, wherein the low-melting-point portion and the high-melting-point portion are arranged along a second direction orthogonal to the first direction, and the melting point of the low-melting-point portion is lower than that of the high-melting-point portion.

[0010] In one of the two heat-insulating materials that sandwich the battery cell from both sides in the first direction, the high-melting-point portion is located on the side further in the second direction than the low-melting-point portion. In the other of the two heat-insulating materials, the high-melting-point portion is located on the other side further in the second direction than the low-melting-point portion.

[0011] In the battery module of the first embodiment, for example, when a battery cell experiences thermal runaway, the heat wave from that battery cell reaches two insulating materials located on both sides of the battery cell. Therefore, the low-melting-point portions of the two insulating materials sometimes melt. In one of the two insulating materials sandwiching the battery cell from both sides in the first direction, the high-melting-point portion is located on the side further in the second direction than the low-melting-point portion; in the other insulating material, the high-melting-point portion is located on the other side further in the second direction than the low-melting-point portion. Therefore, when the low-melting-point portions of the two insulating materials melt, the thermal resistance between the thermally runaway battery cell and the adjacent battery cell easily increases because the thermally runaway battery cell is tilted relative to the adjacent battery cell. Therefore, the battery module of the first embodiment can prevent the heat from the thermally runaway battery cell from being transferred to other battery cells.

[0012] In the second type of battery module, when viewed along a third direction orthogonal to the first and second directions, the end of the battery cell on one side of the second direction is located closer to the boundary between the high melting point portion and the low melting point portion, and the end of the battery cell on the other side of the second direction is located closer to the other side than the boundary portion.

[0013] In the second type of battery module, when the low-melting-point portions of the two insulating materials melt, the thermally runaway battery cell is prone to tilting relative to the adjacent battery cell.

[0014] In the third type of battery module, in the first or second type, the first direction is horizontal and the second direction is vertical.

[0015] In third-party battery modules, when the low-melting-point portions of two insulating materials melt, the thermally runaway battery cell tilts relative to adjacent battery cells due to gravity. Therefore, thermally runaway battery cells are prone to tilting relative to adjacent battery cells.

[0016] In the fourth method of battery module, in the first or second method, the first direction and the second direction are horizontal.

[0017] In the fourth type of battery module, when the low-melting-point portion melts, the vertical position of the high-melting-point portion paired with it is difficult to change due to the melting of the low-melting-point portion. Therefore, the tilting action of the thermally runaway battery cell relative to the adjacent battery cell is easily stabilized.

[0018] In the fifth method of battery module, the battery cell housing is rectangular in shape in any of the first to fourth methods.

[0019] In the fifth type of battery module, when a thermally runaway battery cell tilts, the contact area between the thermally runaway battery cell and the adjacent battery cell tends to decrease.

[0020] As described above, the battery module involved in this invention has the excellent effect of making it difficult for the heat of a thermally runaway battery cell to be transferred to other battery cells. Attached Figure Description

[0021] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein the same symbols denote the same elements, and:

[0022] Figure 1 It is an exploded perspective view of a battery pack having the battery module according to the first embodiment;

[0023] Figure 2 This is a schematic exploded perspective view of some of the components of a battery module;

[0024] Figure 3 This is a schematic side view of a portion of the battery module;

[0025] Figure 4 This is a schematic top view of a portion of the battery module;

[0026] Figure 5 This is a schematic side view of a portion of a battery module during thermal runaway of a battery cell;

[0027] Figure 6 Thermal runaway is caused by Figure 5 A schematic side view of a portion of the battery module as it progresses through its state;

[0028] Figure 7 This is a schematic side view of a portion of the battery module according to the second embodiment;

[0029] Figure 8 This is a schematic top view of a portion of the battery module;

[0030] Figure 9 This is a schematic top view of a portion of a battery module during thermal runaway of a battery cell. Detailed Implementation

[0031] The following is for reference Figures 1 to 6 The battery module according to the first embodiment will be described. In addition, the arrows UP, FR and LH in each figure represent the upper side in the vertical direction of the vehicle, the front side in the longitudinal direction of the vehicle, and the left side in the horizontal direction of the vehicle, respectively.

[0032] The battery module 20 in this embodiment is Figure 1This is a portion of the battery pack 10 shown. The battery pack 10 is mounted in a vehicle. The vehicle in this embodiment is a battery electric vehicle (BEV).

[0033] The battery pack 10 of this embodiment has a battery housing 11 and two battery modules 20. The power of the battery pack 10 (battery unit 23) is supplied, for example, to an electric motor (not shown) for providing driving force to the front and rear wheels of the vehicle.

[0034] like Figure 1 and Figure 2 As shown, the battery housing 11 has a lower housing 12 and an upper housing 14.

[0035] The lower shell 12 is a hollow body with an opening on its upper surface. The upper shell 14 is a hollow body with an opening on its lower surface.

[0036] like Figure 1 As shown, two battery modules 20 are disposed inside the lower housing 12. Each battery module 20 is arranged in a left-right direction.

[0037] like Figure 2 As shown, the battery module 20 has a battery stack 21, a pair of end plates 56 and four constraint components 57.

[0038] The battery stack 21, extending in a front-to-back direction when viewed from above, has multiple battery cells 23 arranged in a front-to-back direction (first direction: horizontal direction), and multiple heat-insulating materials 35 located between adjacent battery cells 23. Furthermore, in Figures 2 to 6 For simplicity, only a few battery cells 23 are depicted in the illustration, but in reality, the battery stack 21 has multiple battery cells 23 (e.g., 30). All battery cells 23 are of the same size. Furthermore, in Figures 2 to 6 For convenience, only a few heat insulation materials 35 are depicted in the text, but in reality, the battery stack 21 has multiple heat insulation materials 35.

[0039] like Figure 2 and Figure 3 As shown, the metal cell housing 24 constituting the shape of the battery cell 23, which is a lithium-ion battery, is rectangular in shape. Specifically, the cell housing 24 has a front panel 25, a rear panel 26, a pair of side panels, a bottom panel, and a top panel. The front panel 25 and the rear panel 26 have substantially the same shape. The front shape of the front panel 25 and the rear panel 26 is a rectangle with a horizontal dimension larger than its vertical dimension. Furthermore, each battery cell 23 has a positive electrode and a negative electrode (both omitted from the diagram).

[0040] like Figure 2 and Figure 3As shown, a heat-insulating material 35 is provided between adjacent battery cells 23 (cell housings 24). The heat-insulating material 35 is a one-piece molded product made of resin. The heat-insulating material 35 has electrical insulation and higher heat insulation properties than the cell housings 24.

[0041] The heat insulation material 35 is roughly rectangular in shape. The vertical dimensions and horizontal width of the heat insulation material 35 are slightly smaller than those of the battery cell 23. The front 36 and rear 37 of the heat insulation material 35 are planes orthogonal to the front-back direction.

[0042] The thermal insulation material 35 has two integral parts. That is, the thermal insulation material 35 has a high melting point part 45 and a low melting point part 50.

[0043] The high-melting-point portion 45 is made of a material with a high melting point. For example, the high-melting-point portion 45 is made of a heat-resistant material (e.g., a ceramic-based heat-insulating material) having a melting point higher than the temperature (600 to 900°C) at which the battery cell 23 experiences thermal runaway. Furthermore, the high-melting-point portion 45 has low thermal conductivity. The low-melting-point portion 50 is made of a material with a lower melting point than the high-melting-point portion 45. For example, the low-melting-point portion 50 is made of a heat-resistant material (e.g., polypropylene) having a melting point lower than the temperature (600 to 900°C) at which the battery cell 23 experiences thermal runaway. The high-melting-point portion 45 and the low-melting-point portion 50 are integrally formed at the boundary surface (boundary portion) 38. The high-melting-point portion 45 and the low-melting-point portion 50 have substantially the same external shape.

[0044] The positions of the high-melting-point portion 45 and the low-melting-point portion 50 in each heat insulation material 35 change every other position in the vertical direction (second direction). That is, as shown... Figures 3 to 6 As shown, in each of the odd-numbered heat insulation materials 35 starting from the front, the high-melting-point portion 45 constitutes the upper half of the heat insulation material 35, and the low-melting-point portion 50 constitutes the lower half of the heat insulation material 35. On the other hand, in each of the even-numbered heat insulation materials 35 starting from the front, the low-melting-point portion 50 constitutes the upper half of the heat insulation material 35, and the high-melting-point portion 45 constitutes the lower half of the heat insulation material 35.

[0045] like Figure 3 and Figure 4 As shown, each heat insulation material 35 is in contact with the front plate portion 25 and the rear plate portion 26 of the cell housing 24 of the adjacent battery cell 23.

[0046] like Figure 2 As shown, the battery module 20 has a pair of end plates 56 at the front and rear. The front end plate 56 is located directly in front of the frontmost battery cell 23, and the rear end plate 56 is located directly behind the rearmost battery cell 23.

[0047] like Figure 2As shown, four constraint members 57 extend in the front-to-back direction, and their cross-sectional shape is approximately L-shaped. Each constraint member 57 covers the four corners of each battery cell 23 (cell housing 24) and end plate 56, and is fixed to the front and rear end plates 56 respectively. Therefore, the front-to-back length of each constraint member 57 becomes shorter than in the free state. That is, the front and rear end plates 56 are pulled closer together by the constraint members 57, thereby clamping the battery stack 21 from the front and back (see...). Figures 3 to 6 (The arrow). Therefore, the adjacent unit housings 24 and the heat insulation material 35 are in strong contact with each other in the front-rear direction. At this time, when the battery module 20 is viewed from the left-right direction (third direction), as shown... Figure 3 As shown, the upper end of each battery cell 23 is located above the boundary surface 38 of each heat insulation material 35, and the lower end of each battery cell 23 is located below the boundary surface 38 of each heat insulation material 35.

[0048] In this way, the battery stack 21 and the end plates 56 are integrated by the constraint components 57. That is, a battery module 20 with battery stack 21, a pair of end plates 56 and four constraint components 57 is completed.

[0049] like Figure 1 As shown, each battery module 20 is housed inside the lower housing 12, and each battery module 20 is fixed to the bottom of the lower housing 12. Furthermore, the entire lower surface of the outer periphery of the upper housing 14 is placed on the entire upper surface of the outer periphery of the lower housing 12, which houses the two battery modules, through a sealing material (not shown), and the lower housing 12 and the upper housing 14 are fixed to each other. Thus, the battery pack 10 is completed. Furthermore, the battery casing 11 of the completed battery pack 10 is supported on the vehicle's body frame component.

[0050] Functions and effects

[0051] Next, the function and effects of the first embodiment will be explained.

[0052] For example, if an internal short circuit occurs in any of the battery cells 23 of the battery module 20, that battery cell 23 may experience thermal runaway. For example, consider... Figures 3 to 6 The battery cell, indicated by reference numeral 23H in the attached figure, experiences thermal runaway.

[0053] When thermal runaway occurs in battery cell 23H, heat is transferred from battery cell 23H to the two heat-insulating materials 35 located on both sides of battery cell 23H. In the following description, the heat-insulating material 35 located directly in front of battery cell 23H is referred to as heat-insulating material 35F, and the heat-insulating material 35 located directly behind battery cell 23H is referred to as heat-insulating material 35R.

[0054] As described above, the melting point of the low-melting-point portion 50 is lower than that of the high-melting-point portion 45. Therefore, as Figure 5 As shown, the following state occurs: due to heat transferred from battery cell 23H to heat insulation materials 35F and 35R, the low-melting-point portion 50 of heat insulation materials 35F and 35R begins to melt, while the high-melting-point portion 45 of heat insulation materials 35F and 35R does not melt. When heat is further transferred from battery cell 23H to heat insulation materials 35F and 35R, as... Figure 6 As shown, the low-melting-point portions 50 of the insulation materials 35F and 35R are completely melted, while the high-melting-point portions 45 of the insulation materials 35F and 35R are not melted. Therefore, the area occupied by the low-melting-point portions 50 of the insulation materials 35F and 35R becomes space.

[0055] Therefore, as Figure 6 As shown, the battery cell 23H, which receives forces generated by the constraint members 57 via the heat insulation materials 35F and 35R, is tilted relative to the heat insulation materials 35F and 35R when viewed from the side. The cell housing 24 of each battery cell 23 is cuboid in shape. Therefore, the upper rear corner 45E1 of the high melting point portion 45 of the heat insulation material 35F is in line contact with the front plate portion 25 of the battery cell 23H, and the lower front corner 45E2 of the high melting point portion 45 of the heat insulation material 35R is in line contact with the rear plate portion 26 of the battery cell 23H. Furthermore, the upper front corner 23HE1 of the battery cell 23H is in line contact with the rear plate portion 26 of the battery cell 23 located directly in front of the heat insulation material 35F. The lower rear corner 23HE2 of the battery cell 23H is in line contact with the front plate portion 25 of the battery cell 23 located directly behind the heat insulation material 35R. Furthermore, a gap is formed between the battery cell 23H and the two battery cells 23 located on the front and rear sides of the battery cell 23H, and a gap is formed between the battery cell 23H and the heat insulation materials 35F and 35R.

[0056] Furthermore, as described above, when viewing the battery module 20 from the left and right, the upper end of each battery cell 23 is located above the boundary surface 38 of each heat insulation material 35, and the lower end of each battery cell 23 is located below the boundary surface 38 of each heat insulation material 35. Consequently, when the low-melting-point portion 50 melts, the battery cell 23H tilts due to its own gravity. Therefore, the battery cell 23H is prone to tilting relative to the heat insulation materials 35F and 35R when viewed from the side.

[0057] Here, will be as Figure 3 and Figure 4 The contact area between the front plate portion 25 of the battery cell 23H and the heat insulation material 35F and the contact area between the rear plate portion 26 of the battery cell 23H and the heat insulation material 35R when the battery cell 23H is in contact with the heat insulation materials 35F and 35R are defined as A0. On the other hand, as shown... Figure 6The contact area between the front panel 25 of the battery cell 23H and the upper rear corner 45E1 of the heat insulation material 35F, and the contact area between the rear panel 26 of the battery cell 23H and the lower front corner 45E2 of the heat insulation material 35R, are defined as A1. In this case, A0 > A1, and the value obtained by dividing A1 by A0 is extremely small. Furthermore, the contact area between the upper front corner 23HE1 of the battery cell 23H and the rear panel 26 of the battery cell 23 located directly in front of the heat insulation material 35F, and the contact area between the lower rear corner 23HE2 of the battery cell 23H and the front panel 25 of the battery cell 23 located directly behind the heat insulation material 35R, are defined as A2. A2 is a small value. For example, A2 is a value much smaller than A0.

[0058] Thus, as Figure 6 The contact area A1 between battery cell 23H and the heat insulation materials 35F and 35R, as well as the contact area A2 between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H, are very small. Therefore, the amount of heat transferred directly from battery cell 23H to the two battery cells 23 located on the front and rear sides of battery cell 23H is small. Furthermore, the amount of heat transferred from battery cell 23H to the two battery cells 23 located on the front and rear sides of battery cell 23H via the heat insulation materials 35F and 35R is also small. That is, the thermal resistance between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H is very high. Therefore, when one battery cell 23 (23H) experiences thermal runaway, it is difficult for thermal cascading to occur between multiple battery cells 23.

[0059] Furthermore, the inventors' experiments confirmed that the larger the tilt angle of battery cell 23H when viewed from the side, the larger the gap between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H, as well as the larger the gap between battery cell 23H and the heat insulation materials 35F and 35R. Moreover, it was confirmed that the thermal resistance between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H increases.

[0060] Next, refer to Figures 7 to 9 The second embodiment of the present invention will be described below. Furthermore, components identical to those in the first embodiment will be given the same reference numerals, and detailed descriptions thereof will be omitted.

[0061] like Figure 7 and Figure 8 As shown, a heat-insulating material 65 is provided between adjacent battery cells 23. The heat-insulating material 65 is a one-piece molded resin product. The heat-insulating material 65 has electrical insulation and higher heat insulation properties than the cell housing 24 of the battery cell 23.

[0062] The shape of the thermal insulation material 65 is approximately the same as that of the thermal insulation material 35. The front 66 and rear 67 of the thermal insulation material 65 are planes orthogonal to the front-back direction.

[0063] The thermal insulation material 65 has two integral parts. That is, the thermal insulation material 65 has a high melting point part 75 and a low melting point part 80.

[0064] The high-melting-point portion 75 is made of a material with a high melting point. The low-melting-point portion 80 is made of a material with a lower melting point than the high-melting-point portion 75. The high-melting-point portion 75 and the low-melting-point portion 80 are integrally formed at the boundary surface (boundary portion) 68. The high-melting-point portion 75 and the low-melting-point portion 80 have substantially the same shape. The high-melting-point portion 75 is made of the same material as the high-melting-point portion 45, and the low-melting-point portion 80 is made of the same material as the low-melting-point portion 50.

[0065] The positions of the high-melting-point portion 75 and the low-melting-point portion 80 in each insulating material 65 vary every other position in the left-right direction (second direction, horizontal direction). That is, as shown... Figure 8 As shown, in each of the odd-numbered heat insulation materials 65 starting from the front, the high-melting-point portion 75 constitutes the right half of the heat insulation material 65, and the low-melting-point portion 80 constitutes the left half of the heat insulation material 65. On the other hand, in each of the even-numbered heat insulation materials 65 starting from the front, the low-melting-point portion 80 constitutes the right half of the heat insulation material 65, and the high-melting-point portion 75 constitutes the left half of the heat insulation material 65.

[0066] like Figure 7 and Figure 8 As shown, each heat insulation material 65 is in contact with the front plate portion 25 and the rear plate portion 26 of the cell housing 24 of the battery cell 23, respectively.

[0067] In battery module 60, also due to the various constraint components 57 (in Figures 7 to 9 (Illustration omitted) so that the front and rear end plates 56 (in) Figures 7 to 9 (Illustration omitted) The cells are pulled closer together. Thus, the front and rear end plates 56 clamp the battery stack 61 containing the battery cells 23 and the heat insulation material 65 from the front and rear. Therefore, adjacent cell housings 24 and heat insulation materials 65 make strong surface contact with each other in the front-rear direction. At this time, when the battery module 60 is viewed along the vertical direction (third direction), as shown... Figure 8 As shown, the right end of each battery cell 23 is located further to the right than the boundary surface 68 of each heat insulation material 65, and the left end of each battery cell 23 is located further to the left than the boundary surface 68 of each heat insulation material 65.

[0068] In this way, the battery stack 61 and the end plates 56 are integrated by the constraint components 57. That is, a battery module 60 with battery stack 61, a pair of end plates 56 and four constraint components 57 is completed.

[0069] Functions and effects

[0070] Next, the function and effects of the second embodiment will be explained.

[0071] For example, if an internal short circuit occurs in any of the battery cells 23 of the battery module 20, that battery cell 23 may experience thermal runaway. For example, consider... Figure 7 and Figure 8 The thermal runaway of a battery cell is indicated by reference numeral 23H in the attached figure.

[0072] When battery cell 23H experiences thermal runaway, heat is transferred from battery cell 23H to the two heat-insulating materials 65 located on both sides of battery cell 23H. In the following description, the heat-insulating material 65 located directly in front of battery cell 23H is referred to as heat-insulating material 65F, and the heat-insulating material 65 located directly behind battery cell 23H is referred to as heat-insulating material 65R.

[0073] As described above, the melting point of the low-melting-point portion 80 is lower than that of the high-melting-point portion 75. Therefore, a state arises where, due to heat transferred from the battery cell 23H to the heat-insulating materials 65F and 65R, the low-melting-point portion 80 of the heat-insulating materials 65F and 65R melts, while the high-melting-point portion 75 of the heat-insulating materials 65F and 65R does not melt. When more heat is transferred from the battery cell 23H to the heat-insulating materials 65F and 65R, such as... Figure 9 As shown, the low-melting-point portions 80 of the insulation materials 65F and 65R are completely melted, while the high-melting-point portions 75 of the insulation materials 65F and 65R are not melted. Therefore, the area occupied by the low-melting-point portions 80 of the insulation materials 65F and 65R becomes space.

[0074] Therefore, the battery cell 23H, which receives the forces generated by the constraint members 57 via the heat insulation materials 65F and 65R, is tilted relative to the heat insulation materials 65F and 65R when viewed from above. As a result, the right rear corner 75E3 of the heat insulation material 65F contacts the front panel 25 of the battery cell 23H, and the left front corner 75E4 of the heat insulation material 65R contacts the rear panel 26 of the battery cell 23H. Furthermore, the right front corner 23HE3 of the battery cell 23H contacts the rear panel 26 of the battery cell 23 located directly in front of the heat insulation material 65F. The left rear corner 23HE4 of the battery cell 23H contacts the front panel 25 of the battery cell 23 located directly behind the heat insulation material 65R. Furthermore, a gap is formed between the battery cell 23H and the two battery cells 23 located on the front and rear sides of the battery cell 23H, and a gap is formed between the battery cell 23H and the heat insulation materials 65F and 65R.

[0075] As described above, in the battery module 60, the right end of each battery cell 23 is located further to the right than the boundary surface 68 of each heat insulation material 65, and the left end of each battery cell 23 is located further to the left than the boundary surface 68 of each heat insulation material 65. Therefore, the battery cell 23H is prone to tilting relative to the heat insulation materials 65F and 65R when viewed from above. Furthermore, in the battery module 60, when the low-melting-point portion 80 of the heat insulation materials 65F and 65R melts, the vertical position of the high-melting-point portion 75 of the heat insulation materials 65F and 65R is less likely to change due to the melting of the low-melting-point portion 80. Therefore, the tilting action of the thermally runaway battery cell 23H relative to the two battery cells 23 located on the front and rear sides of the battery cell 23H is easily stabilized.

[0076] Here, will be as Figure 7 and Figure 8 The contact area between the front plate portion 25 of the battery cell 23H and the heat insulation material 65F and the rear plate portion 26 of the battery cell 23H and the heat insulation material 65R when the battery cell 23H is in contact with the heat insulation materials 65F and 65R is defined as A0. On the other hand, as shown... Figure 9 The contact area between the front panel 25 of the battery cell 23H and the right rear corner 75E3 of the high melting point portion 75 of the heat insulation material 65F, and the contact area between the rear panel 26 of the battery cell 23H and the left front corner 75E4 of the high melting point portion 75 of the heat insulation material 65R, are defined as A1. In this case, A0 > A1, and the value obtained by dividing A1 by A0 is a very small value. Furthermore, the contact area between the right front corner 23HE3 of the battery cell 23H and the rear panel 26 of the battery cell 23 located directly in front of the heat insulation material 65F, and the contact area between the left rear corner 23HE4 of the battery cell 23H and the front panel 25 of the battery cell 23 located directly behind the heat insulation material 65R, are defined as A2. A2 is a small value. For example, A2 is a value much smaller than A0.

[0077] Thus, as Figure 9 The contact area A1 between battery cell 23H and the heat insulation materials 65F and 65R, as well as the contact area A2 between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H, are very small. Therefore, the amount of heat transferred directly from battery cell 23H to the two battery cells 23 located on the front and rear sides of battery cell 23H is small. Furthermore, the amount of heat transferred from battery cell 23H to the two battery cells 23 located on the front and rear sides of battery cell 23H via the heat insulation materials 65F and 65R is also small. That is, the thermal resistance between battery cell 23H and the two battery cells 23 located on the front and rear sides of battery cell 23H is very large. Therefore, when one battery cell 23 (23H) experiences thermal runaway, it is difficult for multiple battery cells 23 to experience thermal cascading.

[0078] Furthermore, the inventors' experiments confirmed that the greater the tilt angle of the battery cell 23H when viewed from above, the larger the gap between the battery cell 23H and the two battery cells 23 located on the front and rear sides of the battery cell 23H, as well as the larger the gap between the battery cell 23H and the heat insulation materials 65F and 65R. Moreover, it was confirmed that the thermal resistance between the battery cell 23H and the two battery cells 23 located on the front and rear sides of the battery cell 23H increases.

[0079] The battery modules of various embodiments have been described above, but these can be appropriately designed and modified without departing from the spirit of the present invention.

[0080] For example, the number of battery cells contained in a battery module can be any number, as long as there are multiple cells.

[0081] For example, the number of battery cells contained in a battery module can be any number, as long as there are multiple cells.

[0082] The vehicle can be an electrified vehicle, which is different from a battery electric vehicle and is equipped with an electric motor that uses electricity from the battery pack. For example, the vehicle can be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV).

Claims

1. A battery module, comprising: Multiple battery cells, the multiple battery cells being arranged along a predetermined first direction; Multiple heat-insulating materials are disposed between adjacent battery cells and in contact with each battery cell; as well as A constraint component applies a force to each of the battery cells in a direction that causes each battery cell to contact the heat-insulating material. in, The thermal insulation material includes a high-melting-point portion and a low-melting-point portion, the low-melting-point portion and the high-melting-point portion being arranged along a second direction orthogonal to the first direction, and the melting point of the low-melting-point portion being lower than that of the high-melting-point portion. In one of the two heat-insulating materials that hold the battery cell from both sides in the first direction, the high-melting-point portion is located on the side further in the second direction than the low-melting-point portion. In the other of the two heat-insulating materials, the high-melting-point portion is located on the other side further in the second direction than the low-melting-point portion.

2. The battery module according to claim 1, wherein, When viewed along a third direction orthogonal to the first and second directions, the end of the battery cell on one side of the second direction is located closer to the boundary between the high melting point portion and the low melting point portion, and the end of the battery cell on the other side of the second direction is located closer to the other side than the boundary portion.

3. The battery module according to claim 1 or 2, wherein, The first direction is the horizontal direction, and the second direction is the vertical direction.

4. The battery module according to claim 1 or 2, wherein, The first direction and the second direction are horizontal.

5. The battery module according to claim 1 or 2, wherein, The battery cell housing is rectangular.

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