Battery module

Abstract

A battery module 1 comprises: an exterior case 2 including a first end wall 11, a second end wall 12, a first longitudinal wall 13, a second longitudinal wall 14, a first vent hole 17, and a second vent hole 18; a battery assembly 3 including battery cells 20 held in a cell holder 30 facing the first end wall 11; a fan 5 forming cooling air CA flowing from the first vent hole 17 toward the second vent hole 18 in the exterior case 2; a cooling air passage 8A defined between a first surface 3a and the first longitudinal wall 13; and a duct member 8 defining a gas passage 8G. The duct member 8 includes a first duct part 81 along a second surface 3b and a second duct part 82 along a third surface 3c. At a corner portion between the first surface 3a and the third surface 3c, the gas passage 8G is connected to the cooling air passage 8A while being directed toward the second end wall 12.

Description

Battery module

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

[0002] Patent Document 1 discloses a battery module in which a discharge path for guiding gas ejected from a battery cell to the outside is provided inside an outer case. The discharge path is disposed between the case end portion and the battery accommodation space. In order to lower the gas temperature before discharging it to the outside, the gas is guided from the battery accommodation space to the case end portion while meandering through the discharge path.

[0003] International Publication No. 2020 / 166501

[0004] Since the discharge path intervenes between the case end portion and the battery accommodation space, the battery accommodation space is narrowed accordingly.

[0005] An object of the present disclosure is to provide a battery module that achieves both a decrease in gas temperature and an improvement in volumetric energy density of the entire battery module.

[0006] One aspect of the present disclosure includes an outer case including a first end wall and a second end wall facing each other in a first direction, a first longitudinal wall and a second longitudinal wall facing each other in a second direction perpendicular to the first direction and connecting the first end wall and the second end wall, a first vent and a second vent provided on the first end wall and the second end wall respectively, a cell holder facing the first end wall within the outer case, a battery assembly including a plurality of battery cells held by the cell holder in a state of being arranged parallel to each other along the second direction, a fan forming cooling air flowing from the first vent toward the second vent within the outer case, a first surface of the battery assembly facing the first longitudinal wall, a cooling air passage defined between the first surface and the first longitudinal wall for guiding the cooling air, a first duct portion along a second surface of the battery assembly facing the second longitudinal wall, and a second duct portion along a third surface of the battery assembly facing the first end wall, and a duct member including a gas passage for guiding gas and defining a gas passage, wherein at a corner portion between the first surface and the third surface, the gas passage communicates with the cooling air passage while facing the second end wall side, to provide a battery module.

[0007] According to this disclosure, it is possible to provide a battery module that achieves both a reduction in gas temperature and an improvement in the overall volumetric energy density of the battery module.

[0008] A perspective view of a battery module according to an embodiment. An exploded perspective view of the battery module of Figure 1, viewed from the opposite side in the longitudinal direction. An exploded perspective view of the battery module of Figure 1. A longitudinal cross-sectional view of the battery module of Figure 1. An exploded perspective view showing a part of the battery assembly of Figure 1. A perspective view of the duct member of Figure 3 in an assembled state, showing the duct member and the base of the outer casing in an exploded state. A partial longitudinal cross-sectional view showing the cooling air passage and gas passage of the battery module of Figure 1. A perspective cross-sectional view showing the cooling air passage and gas passage of the battery module of Figure 1. A plan view showing the area around the confluence of the cooling air passage and gas passage of the battery module of Figure 1.

[0009] A battery module according to one embodiment of the present disclosure includes an outer casing comprising a first end wall and a second end wall facing each other in a first direction, a first longitudinal wall and a second longitudinal wall facing each other in a second direction perpendicular to the first direction and connecting the first end wall and the second end wall, a first vent and a second vent provided on the first end wall and the second end wall, respectively, a cell holder facing the first end wall within the outer casing, and a plurality of battery cells held in the cell holder in a state arranged parallel to each other along the second direction, and within the outer casing, from the first vent to the front The battery assembly comprises a fan that forms cooling air flowing toward a second vent, a first surface of the battery assembly facing the first longitudinal wall, a cooling air passage defined between the first longitudinal wall and the first longitudinal wall for guiding the cooling air, a duct member that defines a gas passage for guiding gas, including a first duct portion along the second surface of the battery assembly facing the second longitudinal wall and a second duct portion along the third surface of the battery assembly facing the first end wall, wherein at the corner between the first surface and the third surface, the gas passage communicates with the cooling air passage while moving toward the second end wall.

[0010] According to the above configuration, the gas passage is arranged along the surface of the battery assembly. This allows the battery assembly to be positioned closer to the end wall of the outer casing, improving the overall volumetric energy density of the battery module. At the corner between the first and third surfaces, the gas flows into the cooling air passage toward the second end wall, then folds back toward the first end wall and can be discharged to the outside of the outer casing through the first vent. This ensures sufficient residence time for the gas before it is discharged to the outside, allowing the gas temperature to be lowered within the outer casing.

[0011] In a battery module according to another embodiment of the present disclosure, the second duct portion may have an inclined portion that is inclined to approach the second end wall as it approaches the first surface.

[0012] With the above configuration, it is easy to supply gas to the cooling air passage towards the second end wall. In addition, the amount of protrusion of the duct member from the battery assembly can be suppressed near the corner between the first surface and the third surface.

[0013] In a battery module according to another embodiment of the present disclosure, the tip of the second duct portion may partially overlap the first surface.

[0014] With the above configuration, even if flames erupt from the battery cells, the tip of the second duct section can prevent the flames from propagating toward the first end wall.

[0015] In a battery module according to another embodiment of the present disclosure, the outer casing may be provided with a projection that protrudes into the space between the cell holder and the first end wall.

[0016] According to the above configuration, if a spark travels from the battery placement space toward the first end wall, it can collide with a protrusion inside the outer casing. This causes the spark to extinguish inside the outer casing, preventing it from being released to the outside via the first end wall.

[0017] A battery module according to another embodiment of the present disclosure may further include a block body disposed between the fan and the second end wall within the outer casing.

[0018] According to the above configuration, if a spark travels from the battery placement space towards the second end wall, it can collide with the block body. The spark will extinguish inside the outer casing, preventing it from being released to the outside through the second end wall.

[0019] A battery module according to another embodiment of the present disclosure may further include a baffle interposed between the block body and the first longitudinal wall.

[0020] According to the above configuration, it is possible to prevent cooling air from flowing into the gap between the block body and the first longitudinal wall. Cooling air can flow smoothly between the first vent and the second vent, improving the cooling performance of the battery module.

[0021] The following describes specific examples of this disclosure in detail based on the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating understanding of the disclosure with reference to the drawings, and the meaning of these terms does not limit the technical scope of this disclosure. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are examples of the technical concept of this disclosure and do not limit this disclosure to them. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended to be illustrative, and not to limit the scope of this disclosure unless specifically stated. Also, the content described in one embodiment or example is applicable to other embodiments or examples. Furthermore, the size and positional relationships of the components shown in the drawings may be exaggerated for clarity in the explanation.

[0022] The battery module of this disclosure is applicable, for example, to emergency power sources such as battery backup units (BBUs). However, this disclosure does not specify the application of the battery module, and it can be used as a power source for various other electrical devices, such as a power source for a vehicle's drive motor.

[0023] Referring to Figures 1 to 4, the battery module 1 according to this embodiment comprises an outer case 2, a battery assembly 3, a block body 4 (fan 5 and DC-DC converter 6), a baffle 7, and a duct member 8.

[0024] The outer casing 2 is, for example, shaped like a rectangular parallelepiped. The outer casing 2 includes a first end wall 11 and a second end wall 12 facing each other in a first direction X, a first longitudinal wall 13 and a second longitudinal wall 14 facing each other in a second direction Z perpendicular to the first direction X and connecting the first end wall 11 and the second end wall 12, and a first side wall 15 and a second side wall 16 facing each other in a third direction Y perpendicular to both the first direction X and the second direction Z and connecting the first end wall 11 and the second end wall 12.

[0025] The first direction X corresponds to the longitudinal direction of the outer case 2. The second direction Z corresponds to the height direction of the outer case 2. In the following description, one side of the second direction Z will be referred to as the "bottom side" and the other side as the "top side". The first longitudinal wall 13 is above the second longitudinal wall 14 and corresponds to the top wall, and the second longitudinal wall 14 corresponds to the bottom wall. The third direction Y corresponds to the width direction of the outer case 2. The first longitudinal wall 13 and the second longitudinal wall 14 are rectangular in shape when viewed from above. The first direction X is the direction in which the longer side of the rectangle extends, and the third direction Y is the direction in which the shorter side of the rectangle extends.

[0026] The outer casing 2 has a first ventilation opening 17 provided in the first end wall 11 and a second ventilation opening 18 provided in the second end wall 12. The first ventilation opening 17 and the second ventilation opening 18 are composed of multiple through holes, which connect the inside and outside of the outer casing 2.

[0027] The outer casing 2 has a base 2A and a cover 2B that are separable in the second direction Z. The base 2A constitutes a second longitudinal wall 14 as a bottom wall. The cover 2B constitutes a first longitudinal wall 13 as a top wall and integrally has a second end wall 12, a first side wall 15 and a second side wall 16. The base 2A has a pair of vertical walls 19 in the third direction Y. The vertical walls 19 are erected from the long side of the first longitudinal wall 13 toward the second direction Z and extend toward the first direction X. The cover 2B is placed over the base 2A from above, and the first side wall 15 and the second side wall 16 are fastened to the pair of vertical walls 19, respectively.

[0028] The outer casing 2 further comprises an end plate 2C that constitutes the first end wall 11 and a pair of columns 2D erected from the first longitudinal wall 13. The pair of columns 2D are positioned on one side in the first direction X relative to the pair of vertical walls 19. The end plate 2C is fastened to the pair of columns 2D.

[0029] The battery assembly 3 and the block body 4 are housed inside the outer casing 2, adjacent to each other in the first direction X. The battery assembly 3 faces the first end wall 11. The block body 4 faces the second end wall 12.

[0030] The block body 4 has a rectangular parallelepiped shape. The fan 5 and the DC-DC converter 6 are unitized within the block body 4. The DC-DC converter 6 converts voltage when outputting DC power discharged and collected by the battery assembly 3 to the outside, or when supplying DC power for charging input from the outside to the battery assembly 3. The fan 5 is positioned between the battery assembly 3 and the DC-DC converter 6 in the first direction X.

[0031] When fan 5 operates, air flows from the outside of the outer case 2 into the inside of the outer case 2 through the first vent 17 and flows in the first direction X inside the outer case 2. In the process, the air absorbs heat from the battery assembly 3, is drawn into fan 5, blown out from fan 5, and absorbs heat from the DC-DC converter 6. The heated air flows out from the inside of the outer case 2 to the outside of the outer case 2 through the second vent. Fan 5 forms a cooling air CA inside the outer case 2, flowing from the first vent 17 to the second vent 18.

[0032] The baffle 7 is interposed between the block body 4 and the second longitudinal wall. The baffle 7 includes a first baffle 7a provided at one end of the upper surface of the block body 4 in the first direction X, and a second baffle 7b provided at the other end of the upper surface of the block body 4 in the first direction X. When the battery module 1 is assembled, the first baffle 7a and the second baffle 7b are in close contact with both the upper surface of the block body 4 and the inner surface of the first longitudinal wall 13. Alternatively, the first baffle 7a and the second baffle 7b may face the inner surface of the first longitudinal wall 13 with a very small clearance between them.

[0033] In this way, the first baffle 7a and the second baffle 7b reduce the clearance between the block body 4 and the outer casing 2. Therefore, the cooling air CA that has passed around the DC-DC converter 6 is prevented from returning to the fan 5 through this clearance. The cooling air CA flows smoothly out of the outer casing 2 through the second vent 18. As a result, the cooling performance of the battery module 1 is improved.

[0034] The duct member 8 covers the first surface 3a, the second surface 3b, and the third surface 3c of the battery assembly 3. The duct member 8 includes a cooling air duct portion 8a that covers the first surface 3a, and a gas duct portion 8b that covers the second and third surfaces. The first surface 3a is the top surface and faces the first longitudinal wall 13 in the second direction Z. The second surface 3b is the bottom surface and faces the second longitudinal wall 14 in the second direction Z. The third surface 3c is one end face in the longitudinal direction and faces the first end wall 11 in the first direction X.

[0035] The cooling air duct section 8a is interposed between the first longitudinal wall 13 and the first surface 3a of the battery assembly 3. The cooling air duct section 8a and the first longitudinal wall 13 define a cooling air passage 8A that guides the cooling air CA. The cooling air CA that flows into the outer casing 2 passes through the cooling air passage 8A and flows toward the other side of the first direction X. After the cooling air CA flows out of the cooling air passage 8A, it is drawn into the fan 5.

[0036] The gas duct portion 8b is L-shaped when viewed in the third direction Y, and includes a first duct portion 81 along the second surface 3b and a second duct portion 82 along the third surface 3c. The gas duct portion 8b, the second surface 3b, and the third surface 3c define a gas passage 8G that guides the gas ejected from the battery assembly 3.

[0037] As just one example, the duct member 8 mainly consists of three parts: an upper duct member 8p, a lower duct member 8q, and a side duct member 8r. The upper duct member 8p constitutes the entirety of the cooling air duct section 8a and the upper end of the second duct section 82. The lower duct member 8q constitutes the entirety of the first duct section 81 and the lower end of the second duct section 82. The side duct member 8r constitutes substantially the entirety of the second duct section 82. Conversely, the cooling air duct section 8a is composed of a part of the upper duct member 8p. The gas duct section 8b is composed of the entirety of the lower duct member 8q, the entirety of the side duct member 8r, and a part of the upper duct member 8p. However, there are no particular limitations on how the parts are divided.

[0038] The gas passage 8G communicates with the cooling air passage 8A at the corner between the first surface 3a and the third surface 3c. The upper duct member 8p constitutes the communication portion between the downstream end of the gas passage 8G and the cooling air passage 8A. Prior to explaining this point, the configuration of the battery assembly 3 will be described.

[0039] Referring to Figures 2 to 5, the battery assembly 3 includes a plurality of battery cells 20, a cell holder 30 that holds the plurality of battery cells 20, a heat transfer element 40 that removes heat from the plurality of battery cells 20, and a current collection structure 50 that electrically connects the plurality of battery cells 20.

[0040] The battery cell 20 is a cylindrical lithium-ion secondary battery. However, the battery cell 20 may be a battery other than a cylindrical type, such as a prismatic battery, or a battery other than a lithium-ion secondary battery, such as an all-solid-state battery.

[0041] The battery cell 20 has a first end face portion 21, a second end face portion 22, and a side portion 23. The battery cell 20 is elongated in its axial direction. The first end face portion 21 and the second end face portion 22 face each other in the cell length direction (axial direction). The side portion 23 connects the periphery of the first end face portion 21 to the periphery of the second end face portion 22. The first end face portion 21 and the second end face portion 22 are circular when viewed in the axial direction. The side portion 23 has a circular cross-section, and its outer diameter is constant in the axial direction. The battery cell 20 has a central electrode 24 provided in the center of the first end face portion 21, and a peripheral electrode 25 provided on the periphery of the first end face portion 21. The central electrode 24 and the peripheral electrode 25 have opposite polarities. For example, the central electrode 24 is the first electrode and is the positive electrode. The peripheral electrode 25 is the second electrode and is the negative electrode. However, the polarity can be reversed.

[0042] The battery cell 20 has a bottomed cylindrical outer casing 26 that houses the electrode body and electrolyte, and a sealing plate 27 that closes the opening of the outer casing 26. The outer casing 26 and the sealing plate 27 are made of a conductive material. The sealing plate 27 is attached to the outer casing 26 via an insulating material (not shown). A safety valve (not shown) is provided in the sealing plate 27 to release gas to the outside of the outer casing 26 when the internal pressure of the battery cell 20 rises. The aforementioned gas passage is configured to guide this gas.

[0043] The cell holder 30 has a plurality of cell housing sections 31 for housing battery cells 20, and a longitudinal wall 32 that covers one end of each cell housing section 31. The plurality of cell housing sections 31 define a space having a shape complementary to the outer shape of the battery cell 20. In this embodiment, the cell housing sections 31 are cylindrical and extend in the second direction Z. The longitudinal wall 32 corresponds to the bottom wall of the cell holder 30 and closes the lower ends of the plurality of cell housing sections 31.

[0044] A plurality of battery cells 20 are respectively housed in a plurality of cell accommodating portions 31 such that the first end face portion 21 faces downward. The first end face portion 21 abuts against the inner surface of the longitudinal wall 32. Thereby, the plurality of battery cells 20 are held by the cell holder 30 in a vertically placed posture with their height positions aligned with each other. The vertically placed posture means a posture in which the axial direction of the battery cell 20 is oriented in the second direction Z (the height direction of the exterior case 2). The plurality of cell accommodating portions 31 and the plurality of battery cells 20 housed therein are arranged in a stagger pattern within the plane (viewed in the second direction Z) in the planes of the first direction X and the third direction Y. The plurality of battery cells 20 form a plurality of rows (for example, 24 rows) of cell rows arranged in the first direction X. In each cell row, a plurality (for example, 3) of battery cells 20 are arranged in the third direction Y.

[0045] When the battery cell 20 is housed in the cell accommodating portion 31, the second end face portion 22 is exposed upward. The heat transfer body 40 is composed of a thermal interface material 41 (TIM: Thermal Interface Material) stacked on the cell holder 30 from above and an insulating sheet 42 stacked on the thermal interface material 41 from above. The thermal interface material 41 contacts the second end face portions 22 of the plurality of battery cells 20. The thermal interface material 41 is made of, for example, a silicon-based material containing a thermally conductive filler and has insulating properties. Therefore, it is possible to prevent the plurality of battery cells 20 from being short-circuited via the heat transfer body 40. The heat generated by the battery cell 20 is transmitted to the insulating sheet 42 via the thermal interface material 41. The insulating sheet 42 forms the first surface 3a of the battery assembly 3. The cooling air duct portion is stacked on the heat transfer body 40 (insulating sheet 42) from above.

[0046] A so-called single-sided current collection is applied to the current collection structure 50. The current collection structure 50 is intensively arranged on the side opposite to the heat transfer body 40 in the second direction Z with respect to the cell holder 30, that is, on the lower side. The plurality of battery cells 20 constitute a plurality of parallel units 28 arranged in the first direction X, and in each parallel unit 28, two or more battery cells 20 are connected in parallel to each other. The plurality of parallel units 28 are sequentially connected in series. The current collection structure 50 realizes such electrical connection between the battery cells 20.

[0047] In this embodiment, as a mere example, the battery assembly 3 has 72 battery cells 20, the 72 battery cells 20 form 12 parallel units 28, and 6 battery cells 20 form 1 parallel unit 28. The 72 battery cells 20 form 24 cell columns, 3 battery cells 20 form 1 cell column, and 2 cell columns form 1 parallel unit 28.

[0048] On the longitudinal wall 32 of the cell holder 30, a plurality of exposed openings 33 (see FIG. 7) for exposing the central electrode 24 and the peripheral electrode 25 are provided corresponding to the plurality of battery cells 20 respectively.

[0049] On the other hand, the current collecting structure 50 is installed on the outer surface of the longitudinal wall 32 and has a plurality of lead plates arranged along the first direction X. The plurality of lead plates include a first end lead plate 51 arranged at one end on the first direction X side, a second end lead plate 52 arranged at the other end on the first direction X side, and a plurality of intermediate lead plates 53 arranged in the first direction X between the first end lead plate 51 and the second end lead plate 52. Each lead plate has a plate-shaped base portion 56 that is overlapped with the cell holder 30, and a plurality of lead wires 57 that extend from the base portion 56, pass through the exposed openings 33, and are connected to the electrodes.

[0050] The first end lead plate 51 is connected to the central electrode 24 of the battery cell 20 that constitutes the parallel unit 28 at one end on the first direction X side. The adjacent intermediate lead plate 53 is connected to the peripheral electrode 25 of the battery cell 20 that constitutes the parallel unit 28, and is also connected to the central electrode 24 of the battery cell 20 that constitutes the parallel unit 28 adjacent to the parallel unit 28. The other intermediate lead plates 53 are the same. The second end lead plate 52 is connected to the peripheral electrode 25 of the battery cell 20 that constitutes the parallel unit 28 at the other end on the first direction X side. Thereby, the parallel connection within each parallel unit 28 and the series connection between the parallel units 28 are realized.

[0051] The battery assembly 3 is provided with a valve plate 70 that is superimposed on the current collection structure 50. The valve plate 70 has a base portion 71 that is laminated on the lead plate and a valve body portion 72 that is continuous with the base portion 71. The valve plate 70 forms the second surface 3b of the battery assembly 3. The first duct portion 81 of the gas duct portion 8b covers the valve plate 70 from below. The upstream portion of the gas passage 8G is defined by the first duct portion 81 and the valve plate 70. When gas is ejected from the battery cell 20, the valve body portion 72 opens, allowing the gas to flow into the back side of the valve plate 70, i.e., into the gas passage 8G.

[0052] Because single-sided current collection is applied to the current collection structure 50, the battery assembly 3 can be miniaturized in the second direction Z compared to the case where the current collection structure 50 is distributed on both sides of the battery assembly 3 in the second direction Z. The first end faces 21 of all battery cells 20 are oriented to the same side (downward). Therefore, each battery cell 20 ejects gas downward. If the gas passage 8G is on the same side as the current collection structure 50 in the second direction Z, it can receive the gas ejected from any of the battery cells 20. The gas passage 8G does not need to be provided on both sides of the battery assembly 3 in the second direction Z, similar to the current collection structure 50. Therefore, space for the cooling air passage 8A can be secured on the side (upper side) where neither the current collection structure 50 nor the gas passage 8G is located. This makes it possible to achieve both improved cooling performance and miniaturization of the battery module 1.

[0053] As shown in Figure 6, the first duct portion 81 of the gas duct portion 8b is flat and is arranged substantially parallel to the second longitudinal wall 14. The second duct portion 82 is plate-shaped and extends in the second direction Z from one end of the first duct portion 81 in the first direction X toward the first surface 3a. The second duct portion 82 covers one end face of the cell holder 30 in the first direction X (see Figure 4). This end face is the third surface 3c of the battery assembly 3.

[0054] As shown in Figure 3, the lower duct member 8q is provided with a first duct section 81 and the lower end of a second duct section 82. The lower end of the side duct member 8r is fastened to the lower end of the second duct section 82 (lower duct member 8q), and the side duct member 8r extends upward from the lower duct member 8q.

[0055] The upper duct member 8p is provided with a cooling air duct section 8a and the upper end of a second duct section 82 that hangs down from one end of the cooling air duct section 8a in the first direction X. The upper duct member 8p is also provided with an opening 83 at one end of the cooling air duct section 8a in the first direction X. The upper end of the second duct section 82 extends downward from the periphery of this opening 83 and is fastened to the upper end of the side duct member 8r.

[0056] The gas passage 8G includes a first passage 8Ga defined by the first duct portion 81 and the lower surface (second surface 3b) of the valve plate 70, and a second passage 8Gb defined by the second duct portion 82 and one end face (third surface 3c) of the cell holder 30 in the first direction X. One end of the first passage 8Ga in the first direction X is spatially in communication with the lower end of the second passage 8Gb. The upper end of the second passage 8Gb, i.e., the downstream end of the gas passage 8G, is in communication with the cooling air passage 8A via the opening 83. The first passage 8Ga is open at the other end in the first direction X.

[0057] Referring to Figures 8 and 9, the gas passage 8G communicates with the cooling air passage 8A at the corner between the first surface 3a and the third surface 3c, while moving toward the second end wall 12 side (the other side of the first direction X).

[0058] In this respect, the opening 83 is an elongated hole that is longer in the third direction Y and shorter in the first direction X. The second duct portion 82 extends in the second direction Z on one side of the first direction X relative to the opening 83.

[0059] The second duct section 82 is provided with a central inclined section 84 in the central part in the second direction Z, and an inclined section 85 at the tip (upper end) in the second direction Z. Both the central inclined section 84 and the inclined section 85 are inclined so as they approach the first surface 3a they approach the second end wall 12. In other words, both the central inclined section 84 and the inclined section 85 are inclined so as they go upwards they move toward the other side of the first direction X. As a result, the gap between the second duct section 82 and the third surface 3c is narrowed in stages. The second passage section 8Gb is relatively wide below the central inclined section 84, and relatively narrow between the central inclined section 84 and the inclined section 85 in the second direction Z. The second passage section 8Gb becomes even narrower in the inclined section 85.

[0060] The inclined portion 85 extends above the cooling air duct portion 8a. The second duct portion 82 has a bent portion 86 that is bent from the upper end of the inclined portion 85 toward the other side in the first direction X. The bent portion 86 is located above the cooling air duct portion 8a and is positioned substantially parallel to the cooling air duct portion 8a.

[0061] An insulating sheet 42 is interposed between the cooling air duct portion 8a and the cell holder 30, and the insulating sheet 42 constitutes the first surface 3a of the battery assembly 3. The insulating sheet 42 protrudes to one side in the first direction X relative to the opening 83. However, the insulating sheet 42 does not abut the inclined portion 85. The inclined portion 85 extends upward from the portion facing the insulating sheet 42 and to the other side in the first direction X. Therefore, the tip of the second duct portion 82 covers the insulating sheet 42, i.e., the first surface 3a, from above. However, the tip of the second duct portion 82 and the first surface 3a are separated in the second direction Z.

[0062] In this embodiment, both ends of the bent portion 86 in the third direction Y are connected to the cooling air duct portion 8a via the stepped wall 87, on the central side of the third direction Y relative to the opening 83. Both ends of the opening 83 protrude to both sides in the third direction Y relative to the stepped wall 87. The bent portion 86 and the stepped wall 87 define the outlet 8Gc of the gas passage 8G. The outlet 8Gc is directed toward the other side of the first direction X.

[0063] An insulating material 90 is provided on the outer surface of the upper duct member. The insulating material 90 is superimposed on the outer surfaces of the inclined portion and the bent portion, extending inclined from the bent portion toward the other side in the first direction X, and is attached to the outer surface of the cooling air duct portion. As a result, the outlet 8Gc and the opening 83 are partially covered with the insulating material 90 with respect to the third direction Y. A printed circuit board 91 is superimposed on the insulating material 90.

[0064] Although detailed illustrations are omitted, the battery module 1 includes a monitoring module that monitors the status of the battery cells 20, and a control device that determines whether there is an abnormality in the battery cells 20 according to the output of the monitoring module, and determines whether the fan 5 can operate based on the determination result. If there is no abnormality in the battery cells 20, the fan 5 operates, and the cooling air CA flows through the cooling air passage 8A toward the other side of the first direction X. There is a sufficient gap between the bent portion 86 and the outer casing 2. Therefore, the second duct portion 82 does not obstruct the flow of the cooling air CA.

[0065] When gas is ejected from the battery cell 20, the fan 5 stops. As a result, airflow is no longer formed by the fan 5. The gas ejected from the battery cell 20 flows into the first passage 8Ga. The gas is high pressure and high temperature and may flow with sparks. Some of the gas is guided to the first duct 81 and flows through the first passage 8Ga toward one side in the first direction X. This gas flows from the end of the first passage 8Ga into the second passage 8Gb, is guided to the second duct 82 and flows upward through the second passage 8Gb. In the process, sparks collide with the central inclined portion 84, the inclined portion 85, the bent portion 86, or the end of the insulating sheet 42 protruding from the opening 83. As a result, sparks are prevented from being ejected from the opening 83.

[0066] The gas is guided by the inclined section 85, passes between the bent section 86 and the insulating sheet 42, and flows out from the outlet 8Gc into the cooling air passage 8A. In accordance with the inclination direction of the inclined section 85 and the orientation of the outlet 8Gc, the gas is blown out from the outlet 8Gc toward the second end wall 12. The outlet 8Gc is covered with insulating material 90, while the space enclosed by the insulating material 90 and the cooling air duct section 8a is open on both sides in the third direction Y. The gas flowing out from the outlet 8Gc also flows in the third direction Y, thereby flowing into the cooling air passage 8A.

[0067] The outlet 8Gc is located on one side of the outer casing 2 in the first direction X, and is close to the first end wall 11. When there is no airflow from the fan 5, the gas is blown out toward the second end wall 12, and then does not flow directly toward the second vent 18, but reverses direction toward one side of the first direction X and flows toward the first vent 17. The gas flow path is naturally reversed within the cooling air passage 8A. The residence time of the gas inside the outer casing 2 is increased, and as a result, the temperature of the gas can be lowered before it reaches the first vent 17.

[0068] The gas duct portion 8b is arranged along the second and third surfaces. Compared to the case where a discharge passage is provided with a portion extending in the first direction X between the first end wall and the battery assembly, the battery module 1 can be miniaturized in the first direction X. As described above, the volumetric energy density of the battery module 1 is improved while obtaining the effect of lowering the gas temperature.

[0069] Sparks flow through the first passage 8Ga toward one side in the first direction X, but do not necessarily enter the second passage 8Gb. Some of the sparks can pass through the gap between the lower duct member and the outer casing and propagate toward one side in the first direction X. As shown in Figures 3, 4, and 6, the base 2A of the outer casing 2 is provided with protrusions 2E on one side in the first direction X of the pair of columns 2D. The protrusions 2E are provided at both ends of the base 2A in the third direction Y. Even if sparks propagate toward one side in the first direction X, they are extinguished by colliding with the protrusions. In this embodiment, the first end wall is made up of an end plate 2C, which is a separate part independent of both the base 2A and the cover 2B. Sparks can be extinguished near the joint between the end plate 2C and the base 2A, and it is possible to effectively prevent sparks from being released outside the outer casing 2 through the gap between the end plate 2C and the base 2A.

[0070] A portion of the gas flowing into the first passage section 8Ga is guided to the first duct section 81 and flows through the first passage section 8Ga toward the other side in the first direction X. Unlike one end, the other end of the first passage section 8Ga is separated from the second end wall 12. A block body 4 exists between the other end of the first passage section 8Ga and the second end wall 12. Therefore, even if sparks propagate from the other end of the first passage section 8Ga toward the other side in the first direction X, they collide with the block body 4 and are extinguished. This effectively prevents sparks from being released to the outside of the outer casing 2 through the second vent 18.

[0071] While embodiments have been described above, the above configuration can be modified as appropriate within the scope of the spirit of this disclosure.

[0072] In the above embodiment, the opening 83 protrudes from the stepped wall 87 on both sides in the third direction Y. The stepped wall 87 may extend outward from the opening 83 in the third direction Y. Also, in the above embodiment, the bent portion 86 is located on one side of the other edge of the opening 83 in the first direction X. The bent portion 86 may reach the other edge of the opening 83, and the opening 83 may be completely hidden by the inclined portion 85 and the bent portion 86 in a plan view. In the above embodiment, the insulating sheet 42 protrudes from the opening 83 on one side in the first direction X. The insulating sheet 42 does not have to reach the opening 83, and the opening 83 does not have to be blocked by the insulating sheet 42.

[0073] This disclosure may include the following aspects: (Aspect 1) An outer case including a first end wall and a second end wall facing each other in a first direction, a first longitudinal wall and a second longitudinal wall facing each other in a second direction perpendicular to the first direction and connecting the first end wall and the second end wall, and a first vent and a second vent provided on the first end wall and the second end wall, respectively; a battery assembly including a cell holder facing the first end wall within the outer case, and a plurality of battery cells held in the cell holder in a state arranged parallel to each other along the second direction; a fan that forms cooling air flowing from the first vent toward the second vent within the outer case; a cooling air passage defined between the first surface of the battery assembly facing the first longitudinal wall and the first longitudinal wall, for guiding the cooling air; a duct member including a first duct portion along the second surface of the battery assembly facing the second longitudinal wall and a second duct portion along the third surface of the battery assembly facing the first end wall, for defining a gas passage for guiding gas, A battery module wherein, at the corner between the first surface and the third surface, the gas passage communicates with the cooling air passage while moving toward the second end wall. (Aspect 2) The battery module according to aspect 1, wherein the second duct portion has an inclined portion that slopes toward the second end wall as it approaches the first surface. (Aspect 3) The battery module according to aspect 1 or 2, wherein the tip of the second duct portion partially overlaps the first surface. (Aspect 4) The battery module according to any one of aspects 1 to 3, wherein the outer casing is provided with a projection that protrudes into the space between the battery assembly and the first end wall. (Aspect 5) The battery module according to any one of aspects 1 to 4, further comprising a block body disposed between the fan and the second end wall within the outer casing. (Aspect 6) The battery module according to aspect 5, further comprising a baffle interposed between the block body and the first longitudinal wall.

[0074] 1 Battery module 2 Outer case 2A Base 2B Cover 2C End plate 2D Column 2E Projection 3 Battery assembly 3a First surface 3b Second surface 3c Third surface 4 Block body 5 Fan 6 DC-DC converter 7 Baffle 7a First baffle 7b Second baffle 8 Duct member 8a Cooling air duct section 8b Gas duct section 8p Upper duct member 8q Lower duct member 8r Side duct member 8A Cooling air passage 8G Gas passage 8Ga First passage section 8Gb Second passage section 8Gc Outlet 11 First end wall 12 Second end wall 13 First longitudinal wall 14 Second longitudinal wall 15 First side wall 16 Second side wall 17 First vent 18 Second vent 19 Vertical wall 20 Battery cell 21 First end face 22 Second end face 23 Side surface 24 Central electrode 25 Peripheral electrode 26 Outer casing 27 Sealing plate 28 Parallel unit 30 Cell holder 31 Cell housing 32 Long wall 33 Exposed opening 40 Heat transfer element 41 Thermal interface material 42 Insulating sheet 50 Current collection structure 51 First end lead plate 52 Second end lead plate 53 Intermediate lead plate 56 Base part 57 Lead wire 70 Valve plate 71 Base part 72 Valve body part 81 First duct part 82 Second duct part 83 Opening 84 Central inclined part 85 Inclined part 86 Bent part 87 Stepped wall 90 Insulating material 91 Printed circuit board CA Cooling air X First direction Y Third direction Z Second direction

Claims

1. An outer casing comprising: a first end wall and a second end wall facing each other in a first direction; a first longitudinal wall and a second longitudinal wall facing each other in a second direction perpendicular to the first direction and connecting the first end wall and the second end wall; a first vent and a second vent provided on the first end wall and the second end wall, respectively; a battery assembly comprising: a cell holder facing the first end wall within the outer casing; and a plurality of battery cells held in the cell holder in a state arranged parallel to each other along the second direction; a fan forming cooling air flowing from the first vent toward the second vent within the outer casing; a cooling air passage defined between the first surface of the battery assembly facing the first longitudinal wall and the first longitudinal wall, for guiding the cooling air; a duct member defining a gas passage for guiding gas, comprising: a first duct portion along the second surface of the battery assembly facing the second longitudinal wall; and a second duct portion along the third surface of the battery assembly facing the first end wall. A battery module in which, at the corner between the first surface and the third surface, the gas passage communicates with the cooling air passage while moving toward the second end wall.

2. The battery module according to claim 1, wherein the second duct portion has an inclined portion that slopes toward the second end wall as it approaches the first surface.

3. The battery module according to claim 1, wherein the tip of the second duct portion partially covers the first surface.

4. The battery module according to any one of claims 1 to 3, wherein the outer casing is provided with a projection that protrudes into the space between the battery assembly and the first end wall.

5. The battery module according to any one of claims 1 to 3, further comprising a block body disposed between the fan and the second end wall within the outer casing.

6. The battery module according to claim 5, further comprising a baffle interposed between the block body and the first longitudinal wall.

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