Battery module

Abstract

A battery module 1 comprises a plurality of battery cells 10, an exterior case 2 that accommodates the plurality of battery cells 10, a discharge port 2a that is provided in the exterior case 2 and discharges gas from the exterior case 2, and a filter 70 that covers the discharge port 2a. The filter 70 is plate-shaped and has a plurality of holes 73. The plurality of holes 73 pass through the filter 70 in the thickness direction and are arranged to fill at least a portion of an opening surface 70a that is orthogonal to the thickness direction.

Description

Battery module

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

[0002] Patent Document 1 discloses a battery module including an exterior case provided with ventilation holes. The ventilation holes are covered with a metal filter. High-temperature gas generated inside the exterior case is discharged to the outside of the exterior case through the ventilation holes and the filter. The filter is composed of a punching metal having a plurality of circular holes or a wire mesh formed from thin wire.

[0003] Japanese Unexamined Patent Application Publication No. 2009-212081

[0004] In the punching metal, a plurality of circular holes are dispersedly arranged. Therefore, when the punching metal is applied to the filter, the air permeability becomes low. In order to ensure air permeability, it is necessary to increase the size of the filter to expand the opening area. On the other hand, the heat capacity of the thin wire is small. Therefore, when a wire mesh is applied to the filter, it is difficult to sufficiently ensure the durability of the gas against heat.

[0005] The present disclosure aims to improve the air permeability and durability of a filter through which high-temperature gas passes.

[0006] One aspect of the present disclosure provides a battery module including a plurality of battery cells, an exterior case housing the plurality of battery cells, an exhaust port provided in the exterior case for discharging gas from the exterior case, and a filter having a plurality of holes and covering the exhaust port, wherein the filter is plate-shaped, the plurality of holes penetrate in the thickness direction of the filter, and are arranged so as to be filled in at least a part of an opening surface orthogonal to the thickness direction.

[0007] According to the present disclosure, the air permeability and durability of a filter through which high-temperature gas passes can be improved.

[0008] A perspective view of a battery module according to an embodiment. An exploded perspective view of the battery module in Figure 1. An exploded perspective view of the battery assembly in Figure 2. An exploded perspective view of the battery block in Figure 3. An exploded perspective view of the spacer and its surrounding components in Figure 3. An exploded perspective view of the upper case, filter, and case safety valve in Figure 2, viewed from below. A plan view of the filter in Figure 2. An enlarged view of Figure 7. A cross-sectional view of the filter cut along the line IX-IX in Figure 8. A longitudinal cross-sectional view of the battery module in Figure 1. An enlarged view of Figure 10. A plan view of the filter according to the first modified example. A plan view of the filter according to the second modified example.

[0009] A battery module according to one embodiment of the present disclosure comprises a plurality of battery cells, an outer case housing the plurality of battery cells, an exhaust port provided in the outer case for discharging gas from the outer case, and a filter having a plurality of holes and covering the exhaust port, wherein the filter is plate-shaped, and the plurality of holes penetrate through the thickness direction of the filter and are arranged to fill at least a portion of the opening surface perpendicular to the thickness direction.

[0010] According to the above configuration, the filter is plate-shaped and has a certain dimension in the thickness direction. Therefore, the heat capacity of the filter is large. Even when high-temperature gas passes through the filter and exhaust port, durability against the heat of the gas can be ensured. For example, melting of the filter due to the heat of the gas can be suppressed.

[0011] Furthermore, the multiple holes in the filter are arranged so as to fill at least a portion of the opening surface perpendicular to the thickness direction of the filter. As a result, the void ratio (the percentage of holes occupying the opening surface of the filter) is higher compared to a configuration in which perfectly circular holes are dispersed. This improves the air permeability of the filter and thus contributes to the miniaturization of the filter.

[0012] In a battery module according to another embodiment of this disclosure, each of the multiple holes may be a convex parallel hexagon. A convex polygon is a polygon in which all interior angles are less than 180 degrees. A parallel hexagon is a hexagon in which all three pairs of opposite sides are parallel and of equal length.

[0013] In practice, even when attempting to fill a plane with multiple holes, the filter must have a portion (grid portion) that defines the multiple holes. The grid portion forms the outline of the shape applied to the holes and defines the boundaries between adjacent holes. Due to the presence of the grid portion, the void ratio can never be 100%.

[0014] Various shapes can tile a plane, including any triangle, any quadrilateral, and any parallelepiped. Among these tileable shapes, a convex parallelepiped has the smallest perimeter per unit area. For example, a regular hexagon is a special form of a convex parallelepiped, and it has the smallest perimeter per unit area among all tileable shapes. Therefore, if the hole is a convex parallelepiped, the portion essential for defining the hole (the grid) can be made as small or narrow as possible, resulting in a higher void ratio and thus higher air permeability.

[0015] In a battery module according to another embodiment of the present disclosure, the thickness of the filter plate may be 1 to 5 mm.

[0016] The above configuration ensures the heat capacity and, consequently, the durability of the filter.

[0017] In a battery module according to another embodiment of the present disclosure, the filter may have a grid portion defining a plurality of holes, and the cross-section of the grid portion may be a rectangular shape that is elongated in the thickness direction.

[0018] With the above configuration, the occupancy rate of the grid portion within the opening surface is reduced. In addition, the second moment of area of ​​the filter increases with respect to bending in the direction of gas passage.

[0019] 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.

[0020] The battery module of this disclosure is applicable, for example, to emergency power sources such as battery backup units (BBUs) or to power the drive motors of electric vehicles. 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.

[0021] Referring to Figures 1 and 2, the battery module 1 according to this embodiment comprises an outer case 2, a battery assembly 3, a substrate unit 6, a case safety valve 65, and a filter 70.

[0022] The outer casing 2 is made of an insulating material. For example, the outer casing 2 is rectangular in shape, and when viewed in the height direction Z (i.e., in a plan view), it is rectangular. For the sake of explanation, the direction in which the longer side of the rectangle extends will be called the "longitudinal direction X," and the direction in which the shorter side extends will be called the "width direction Y." The longitudinal direction X, the width direction Y, and the height direction Z are each perpendicular to the other two directions.

[0023] The outer casing 2 has a lower case 61 and an upper case 62 that can be divided in the height direction Z. The lower case 61 is a rectangular box shape that opens upward, and the upper case 62 is a rectangular box shape that opens downward. The opening edges of the lower case 61 and the upper case 62 are fastened together in a state where they are superimposed in the height direction Z. This defines the internal space of the outer casing 2. The battery assembly 3 and the circuit board unit 6 are housed in the internal space. The case safety valve 65 and the filter 70 are attached to the outer casing 2.

[0024] Referring to Figures 2 and 3, the battery assembly 3 comprises one or more battery blocks 4 and spacers 5. The multiple battery blocks 4 have similar configurations to each other. The multiple battery blocks 4 are fixed to the spacers 5 and positioned with a gap between them. Hereinafter, when simply referred to as "gap," it refers to the gap between the battery blocks 4.

[0025] In this embodiment, two battery blocks 4 are arranged in the height direction Z. The first battery block 4A is placed on top of the spacer 5, and the second battery block 4B is placed on the bottom of the spacer 5.

[0026] The battery block 4 includes a plurality of battery cells 10, a cell holder 20 that holds the plurality of battery cells 10, and a current collection structure 40 that electrically connects the plurality of battery cells 10 held in the cell holder 20.

[0027] The battery cell 10 is a cylindrical lithium-ion secondary battery. However, the battery cell 10 may be a battery other than a cylindrical shape, such as a prismatic battery, or a battery other than a lithium-ion secondary battery, such as an all-solid-state battery.

[0028] The battery cell 10 comprises a bottomed cylindrical outer casing 11 that houses electrodes and electrolyte, and a closing member 12 that closes the opening of the outer casing 11. The outer casing 11 and the closing member 12 are made of a conductive material. The closing member 12 is attached to the outer casing 11 via an insulating material. The battery cell 10 has a pair of end faces that are spaced apart in the axial direction. Hereinafter, the end face on the side where the closing member 12 is provided will be referred to as the "top 13," and the end face on the opposite side will be referred to as the "bottom 14." The top 13 is mainly composed of the closing member 12. The outer casing 11 comprises the peripheral edge of the top 13, the bottom 14, and the side surface connecting the top 13 and the bottom 14.

[0029] The outer can 11 and the closing member 12 have opposite polarities. For example, the closing member 12 (including the central part of the top 13) is the anode, and the outer can 11 (the peripheral part of the top 13 and the bottom 14) is the negative electrode. However, the polarities may be reversed.

[0030] The cell holder 20 has multiple cell housing sections 21 that individually house multiple battery cells 10. By housing the multiple battery cells 10 in the multiple cell housing sections 21, the multiple battery cells 10 are held in the cell holder 20 in a vertical orientation with their heights aligned. The "vertical orientation" is an orientation in which the axial direction (cell length direction) of the battery cell 10 is oriented in the height direction Z.

[0031] The cell housing section 21 defines a space having a shape complementary to the outer shape of the battery cell 10. In this embodiment, the cell housing section 21 is cylindrical and extends in the height direction Z.

[0032] The cell holder 20 has a pair of conductive plate mounting portions 22 on both sides in the height direction Z that close off the space defined by the cell housing portion 21. Figures 3 and 4 are perspective views from above, and the conductive plate mounting portions 22 on the upper side of each battery block 4 are explicitly shown.

[0033] In this embodiment, the cell holder 20 is composed of a first holder member 26 and a second holder member 27 that can be divided in the height direction Z. The first holder member 26 faces another battery block 4 in the height direction Z. The second holder member 27 is on the opposite side from the spacer 5 when viewed from the first holder member 26.

[0034] Since the first battery block 4A is positioned on top of the spacer 5, the first holder member 26 is on the lower side and the second holder member 27 is on the upper side. Conversely, since the second battery block 4B is positioned below the spacer 5, the first holder member 26 is on the upper side and the second holder member 27 is on the lower side.

[0035] The cell housing section 21 is composed of a first half 26a provided on the first holder member 26 and a second half 27a provided on the second holder member 27. The first half 26a and the second half 27a are bottomed cylindrical shapes. The first half 26a is open on the second holder member 27 side and closed on the spacer 5 side by the conductive plate installation section 22. The second half 27a is open on the first holder member 26 side and closed on the opposite side by the conductive plate installation section 22.

[0036] By assembling the first holder member 26 and the second holder member 27 together in the height direction Z, a pair of first halves 26a and second halves 27a are aligned with each other in the height direction Z, forming a single cell housing section 21. Half of the battery cell 10 is housed in the first half 26a (see Figures 4 and 5). The remainder is housed in the second half 27a (see Figure 4).

[0037] Referring to Figure 4, in each battery block 4, multiple battery cells 10 form multiple cell rows 15 arranged in the longitudinal direction X, and in each cell row 15, multiple battery cells 10 are arranged in the width direction Y. In addition, in each battery block 4, multiple battery cells 10 constitute multiple parallel units 16. Each parallel unit 16 consists of two or more battery cells 10 that constitute one cell row 15 or multiple adjacent cell rows 15. In each parallel unit 16, the two or more battery cells 10 are connected in parallel to each other. Multiple parallel units 16 are connected in series sequentially.

[0038] As just one example, in this embodiment, the battery block 4 has 90 battery cells 10. That is, 90 battery cells 10 constitute 9 parallel units 16, and 10 battery cells 10 constitute one parallel unit 16. 90 battery cells 10 form 18 rows of cells 15, and 5 battery cells 10 form 1 row of cells 15. One parallel unit 16 is composed of two adjacent rows of cells 15, and the nine parallel units 16 are arranged in the longitudinal direction X.

[0039] Referring to Figures 3 to 5, the current collection structure 40 employs a so-called double-sided current collection system, in which current collection cells are distributed on both sides in the height direction Z as viewed from the cell holder 20 or the battery cell 10. In this case, two or more battery cells 10 constituting the same single parallel unit 16 are all held in the cell holder 20 with their tops 13 facing the same side. Parallel units 16 with their tops 13 facing upwards and parallel units 16 with their tops 13 facing downwards are arranged alternately in the longitudinal direction X.

[0040] Each of the pair of conductive plate mounting sections 22 has multiple openings that partially expose the end faces of each of the multiple battery cells 10. The current collection structure 40 has a first current collection section 41 installed in the conductive plate mounting section 22 on the spacer 5 side, and a second current collection section 46 installed in the conductive plate mounting section 22 on the opposite side. Both the first current collection section 41 and the second current collection section 46 have multiple conductive plates 42, 47 stacked on the conductive plate mounting section 22 and arranged in the longitudinal direction X, and insulating plates 43, 48 stacked on the side opposite to the cell holder 20 when viewed from the conductive plates 42, 47. Each conductive plate 42, 47 is mechanically and electrically connected to the electrodes of one or two parallel units 16 of battery cells 10 through the openings in the conductive plate mounting section 22.

[0041] The number of parallel units 16 and the number of battery cells 10 constituting each parallel unit 16 are the same across the multiple battery blocks 4. The multiple battery cells 10 constituting the first battery block 4A are opposite each of the multiple battery cells 10 constituting the second battery block 4B in the height direction Z, with a gap in between. Hereinafter, a battery cell 10 with its top 13 facing the gap will be called a "top-facing cell 10T", and a battery cell 10 with its bottom 14 facing the gap will be called a "bottom-facing cell 10B".

[0042] The top-facing cell 10T of the first battery block 4A faces the bottom-facing cell 10B of the second battery block 4B with a gap therebetween. The bottom-facing cell 10B of the first battery block 4A faces the top-facing cell 10T of the second battery block 4B with a gap therebetween.

[0043] As a mere example, in the first battery block 4A, the odd-numbered parallel units 16 counted from one side in the longitudinal direction X (the lower left side in FIG. 5) are constituted by the top-facing cells 10T, and the even-numbered parallel units 16 are constituted by the bottom-facing cells 10B. In that case, in the second battery block 4B, the odd-numbered parallel units 16 are constituted by the bottom-facing cells 10B, and the even-numbered parallel units 16 are constituted by the top-facing cells 10T.

[0044] In the present embodiment, the spacer 5 has an intermediate partition wall 31 extending in the longitudinal direction X and the width direction Y, and peripheral walls 32 extending from the peripheral edge of the intermediate partition wall 31 to both sides in the height direction Z. The spacer 5 has a first space 5a defined by the upper surface of the intermediate partition wall 31 and the inner peripheral surface of the upper part of the peripheral wall 32 and open upward, and a second space 5b defined by the lower surface of the intermediate partition wall 31 and the inner peripheral surface of the lower part of the peripheral wall 32 and open downward.

[0045] The first battery block 4A is partially accommodated in the first space 5a. By fastening the cell holder 20 (particularly, the first holder member 26 accommodated in the first space 5a) to the upper part of the peripheral wall 32, the first battery block 4A is fixed above the spacer 5. The lowermost layer of the first battery block 4A (in this example, the insulating plate 43 of the first current collector 41) is in a state slightly separated upward from the upper surface of the intermediate partition wall 31.

[0046] The same applies to the second battery block 4B. The second battery block 4B is partially accommodated in the second space 5b. By fastening the cell holder 20 (particularly, the first holder member 26 accommodated in the second space 5b) to the lower part of the peripheral wall 32, the second battery block 4B is fixed below the spacer 5. The uppermost layer of the second battery block 4B (in this example, the insulating plate 43 of the first current collector 41) is in a state slightly separated downward from the lower surface of the intermediate partition wall 31.

[0047] Referring to FIG. 2, the substrate unit 6 includes a printed circuit board 51 and a substrate holder 52 that holds the printed circuit board 51. The printed circuit board 51 is formed by welding electronic components 51a (see FIG. 11) at required positions on a wiring board formed by wiring on an insulating plate material. The substrate unit 6 is stacked on the upper side of the battery assembly 3 (in this example, on the upper side of the insulating plate 48 of the second current collector portion 46 of the first battery block 4A) and fastened to the battery assembly 3. The battery assembly 3 is connected to the wiring on the printed circuit board 51 via a plurality of harnesses 56. The harnesses 56 are routed within the space between the battery assembly 3 and the outer case 2.

[0048] Here, during the operation of the battery module 1, due to some abnormality, the interior of a certain battery cell 10 may become extremely hot. When the internal pressure of the battery cell 10 rises, the closing member 12 that constitutes the top portion 13 detaches from the outer can 11, or a cell safety valve (not shown in detail) provided on the closing member 12 opens. As a result, the high-temperature and high-pressure gas is discharged from the outer can 11 through the top portion 13 to the outside of the battery cell 10.

[0049] The top portion 13 of the top-facing cell 10T is covered by the first current collector portion 41. A plurality of current collection safety valves 44 are provided at positions on the insulating plate 43 of the first current collector portion 41 that face the top-facing cell 10T in the height direction Z, respectively.

[0050] When gas is generated in the top-facing cell 10T of the first battery block 4A, the current collection safety valve 44 opens due to the gas pressure. The gas flows into the first assembly internal passage 81 defined by the lowermost layer of the first battery block 4A and the upper surface of the intermediate partition 31.

[0051] When gas is generated in the top-facing cell 10T of the second battery block 4B, similarly, the current collection safety valve 44 opens due to the gas pressure. The gas flows into the second assembly internal passage 82 defined by the uppermost layer of the second battery block 4B and the lower surface of the intermediate partition 31.

[0052] The top portion 13 of the bottom opposing cell 10B is covered by the second current collector 46. The insulating plate 48 of the second current collector 46 is also provided with multiple current collection safety valves (not shown) at positions opposite to the bottom opposing cell 10B in the height direction Z.

[0053] Referring to Figures 6, 10, and 11, the outer casing 2 is provided with an exhaust port 2a for discharging gas from the outer casing 2, and a filter 70 covers the exhaust port 2a from the inside. In this embodiment, the exhaust port 2a penetrates the top wall 62a of the upper casing 62, particularly its central portion. The filter 70 is plate-shaped. The filter 70 has a plurality of holes 73 to allow gas to pass through. High-temperature and high-pressure gas is discharged to the outside of the outer casing 2 through the gas passage 80 formed inside the outer casing 2, the filter 70, and the exhaust port 2a.

[0054] Referring to Figure 10, the gas passage 80 includes the first assembly internal passage 81 and the second assembly internal passage 82 described above. The gas passage 80 includes a vertical passage 83 defined by the side surface of the battery assembly 3 and the inner surface of the side wall of the outer case 2, extending in the height direction Z. The gas passage 80 also includes a downstream passage 84 defined by the top surface of the substrate unit 6 and the inner surface of the top wall 62a of the upper case 62, extending horizontally. The exhaust port 2a is open to the downstream passage 84 via the filter 70.

[0055] Furthermore, the peripheral wall 32 of the spacer 5 is provided with a slit 33 and a notch 34. The first assembly internal passage 81 and the second assembly internal passage 82 communicate with the vertical passage 83 via the slit 33 or notch 34, communicate with the downstream passage 84 via the vertical passage 83, and communicate with the exhaust port 2a via the downstream passage 84 and the filter 70.

[0056] The exhaust port 2a is provided in the top wall 62a of the upper case 62, opening the downstream passage 84 to the outside of the outer case 2. The upper case 62 is provided with a cylindrical valve housing 2b that surrounds the exhaust port 2a and protrudes upward from the top wall 62a. The case safety valve 65 has a valve body 65a housed in the valve housing 2b and a stem 65b that protrudes downward from the valve body 65a and is inserted into the exhaust port 2a. When the pressure in the downstream passage 84 rises, the case safety valve 65 moves upward and the exhaust port 2a is opened.

[0057] The upper case 62 is provided with a filter housing 2c that surrounds the exhaust port 2a and protrudes downward from the top wall 62a. The filter housing 2c is a stepped cylindrical shape having an upper small-diameter portion 2d through which the exhaust port 2a is opened, and a lower large-diameter portion 2e facing the downstream passage 84. Between the small-diameter portion 2d and the large-diameter portion 2e, the filter housing 2c has a downward-facing annular stepped surface 2f.

[0058] The filter 70 is fixed to the outer casing 2 in a state where it abuts against the stepped surface 2f. The filter 70 may also be adhered to the stepped surface 2f via tape 66. The filter 70 may also be fitted to the upper casing 62 with claws or screwed in.

[0059] Referring to Figure 7, the filter 70 has a solid outer periphery 71 and a ventilation portion 72 inside the outer periphery 71. In plan view (viewed in the thickness direction of the filter 70), the filter 70 is circular, the outer periphery 71 is annular, and the ventilation portion 72 is circular. The ventilation portion 72 is provided with a plurality of holes 73 for the passage of gas. All of the plurality of holes 73 penetrate through the thickness direction of the filter 70 and open into a pair of end faces of the filter 70 (hereinafter referred to as opening faces 70a) perpendicular to the thickness direction. The ventilation portion 72 is provided with a grid portion 74 that defines the plurality of holes 73.

[0060] The tape 66 is attached to the end face of the outer periphery 71. The entire outer periphery 71 and the peripheral edge of the ventilation portion 72 abut against the stepped surface 2f (see Figure 11). The gas in the downstream passage 84 passes through the holes 73 of the filter 70 inside the stepped surface 2f, flows into the small diameter portion 2d of the filter housing 2c, and flows out to the outside of the outer casing 2 through the exhaust port 2a.

[0061] In Figure 7, the inner edge of the stepped surface 2f, i.e., the inner circumferential surface of the small-diameter portion 2d, is projected. The area inside this region can effectively allow gas to pass through. Hereafter, this region of the opening surface 70a will be referred to as the "effective surface," and the area of ​​this region will be referred to as the "effective area." Also, for the sake of explanation, hereafter, the ratio of the area occupied by the holes 73 to the effective area within this effective surface will be referred to as the "void ratio."

[0062] The multiple holes 73 are arranged to fill at least a portion of the opening surface 70a. In this embodiment, the multiple holes 73 are planar filling over the entire area of ​​the opening surface 70a (particularly the effective surface of which).

[0063] Furthermore, the shapes of the multiple holes 73 are congruent to each other. The multiple holes 73 are laid out within the opening surface 70a by so-called monohedral tessellation. While the holes 73 are arranged to fill the plane, the presence of the grid portion 74 prevents the void ratio from being a perfect 100%.

[0064] Referring to Figure 8, in this embodiment, as an example, the shape of the hole 73 is a convex parallel hexagon. A parallel hexagon is an example of a figure that can tile a plane. In a convex polygon, all interior angles are less than 180 degrees. In a parallel hexagon, for any of the three pairs of opposite sides, the opposite sides are parallel and of equal length.

[0065] All quadrilaterals can be combined to form a parallel hexagon by combining two congruent quadrilaterals. In this embodiment, the parallel hexagon shape of the hole 73 is obtained by combining two congruent isosceles trapezoids such that their lower bases completely overlap. In this isosceles trapezoid, if the base angle (the angle between the lower base and the leg) is not 60 degrees, and / or if the upper base and the leg are not of equal length, the shape of the hole 73 becomes a parallel hexagon with four equal sides. If the base angle is 60 degrees and the upper base and the leg are of equal length, the shape of the hole 73 becomes a regular hexagon, which is a special form of a convex parallel hexagon.

[0066] Here, the figure with the smallest perimeter for a predetermined unit area (for example, 1 square centimeter) is a perfect circle. A regular hexagon can be both inscribed in and circumscribed around a perfect circle, is close to a perfect circle, and, if limited to figures that allow for single-tile laying, has the smallest perimeter for a unit area.

[0067] A convex parallel hexagon (even if it is not a regular hexagon) is closer to a perfect circle than other shapes that allow for single-tile laying (for example, triangles or quadrilaterals). Therefore, when a convex parallel hexagon is applied to the shape of the hole 73, the length and area of ​​the grid portion 74 surrounding the hole 73 can be made as small as possible relative to the area of ​​the hole 73. In other words, the void ratio is improved.

[0068] In Figure 8, a parallel hexagon (hereinafter referred to as the outer shape 79) surrounding one hole 73 is drawn with a dashed line. The outer shape 79 follows the center of the width of the grid section 74. The width W74 of the grid section 74 is very narrow. In the illustrated example, the ratio of the area of ​​one hole 73 to the area of ​​the outer shape 79 is 96.5%, and this ratio is approximately equal to the void ratio. Thus, according to this embodiment, a high void ratio can be achieved that is difficult to obtain with perforated metal in which circular holes are dispersed.

[0069] A high void ratio increases the air permeability of the filter 70. Therefore, the effective area required for gas ventilation can be reduced, and the filter 70 can be made smaller. The filter housing 2c can be made smaller, and space can be secured around the exhaust port 2a for placing components other than the filter 70.

[0070] Referring to Figure 9, the plate thickness T70 of the filter 70 is, for example, 1 to 5 mm, which is sufficiently large compared to the diameter of the fine wire used in the manufacture of the wire mesh. Therefore, as described above, the heat capacity of the filter 70 is increased while increasing the void ratio. Even if the gas is at a high temperature, melting of the filter 70 can be prevented. Furthermore, the outer circumference 71 of the filter 70 is solid. From this point as well, the heat capacity of the filter 70 is effectively improved.

[0071] As described above, the width W74 of the grid section 74 is very narrow, while the height H74 of the grid section 74 is equivalent to the plate thickness T70 of the filter 70. The cross-section of the grid section 74 is a long rectangle in the thickness direction of the filter 70. Therefore, the second moment of area of ​​the filter 70 is high when bent in the direction through which the gas passes.

[0072] The filter 70 is made of a metal material. The method of manufacturing the filter 70 is not particularly limited. For example, a filter 70 having the above structure can be manufactured by etching or punching a circular, flat blank. The filter 70 can also be manufactured by laminating, stretching, and / or cutting block materials.

[0073] While embodiments have been described above, the above configuration can be modified as appropriate within the scope of the spirit of this disclosure.

[0074] The shape of the holes 73 in the filter 70 is not limited to a convex parallel hexagon. Referring to Figure 12, the shape of the holes 73 may be any triangle, for example, an equilateral triangle. Referring to Figure 13, the shape of the holes 73 may be any quadrilateral, for example, a square. Any triangle and any quadrilateral are figures that can tile a plane. The shape of the holes 73 may also be a concave parallel hexagon. The shape of the holes 73 may also be a pentagon obtained by dividing a parallel hexagon with a line passing through its center.

[0075] The shape of the holes 73 in the filter 70 is not limited to one type. There may be two or more types of hole shapes, as long as the holes 73 can be arranged to fill the opening surface. Examples of combinations of two or more shapes include a combination of one equilateral triangle and two regular dodecagons, or a combination of one equilateral triangle, two squares, and one regular hexagon.

[0076] The multiple holes 73 only need to be arranged so as to fill at least a portion of the opening surface 70a, and do not necessarily need to fill the entire opening surface 70a or its effective surface. The opening surface 70a may be partially closed.

[0077] In the above embodiment, the battery assembly 3 has two battery blocks 4. The number of battery blocks 4 is not particularly limited and may be one or three or more.

[0078] The configuration of the gas passage 80 can be appropriately changed depending on the configuration of the outer casing 2 and the battery assembly 3. The exhaust port 2a and the filter 70 only need to be provided in the outer casing 2, and their positions are not particularly limited.

[0079] (Aspect 1) A battery module comprising: a plurality of battery cells; an outer case housing the plurality of battery cells; an exhaust port provided in the outer case for discharging gas from the outer case; and a filter having a plurality of holes and covering the exhaust port, wherein the filter is plate-shaped, and the plurality of holes are arranged to penetrate the thickness direction of the filter and fill at least a portion of the opening surface perpendicular to the thickness direction. (Aspect 2) The battery module according to Aspect 1, wherein each of the plurality of holes is a convex parallel hexagon. (Aspect 3) The battery module according to Aspect 1 or 2, wherein the plate thickness of the filter is 1 to 5 mm. (Aspect 4) The battery module according to any one of Aspects 1 to 3, wherein the filter has a grid portion defining the plurality of holes, and the cross-section of the grid portion is a long rectangle in the thickness direction.

[0080] 1 Battery module 2 Outer case 2a Exhaust port 2b Valve housing 2c Filter housing 2d Small diameter section 2e Large diameter section 2f Stepped surface 3 Battery assembly 4 Battery block 4A First battery block 4B Second battery block 5 Spacer 5a First space 5b Second space 6 Circuit board unit 10 Battery cell 10T Top opposing cell 10B Bottom opposing cell 11 Outer can 12 Closing member 13 Top section 14 Bottom section 15 Cell row 16 Parallel unit 20 Cell holder 21 Cell housing section 22 Conductive plate installation section 26 First holder member 26a First half 27 Second holder member 27a Second half 31 Intermediate spacing wall 32 Peripheral wall 33 Slit 34 Notch 40 Current collection structure 41 First current collector 46 Second current collector 42, 47 Conductive plate 43, 48 Insulating plate 44 Current collector safety valve 51 Printed circuit board 51a Electronic component 52 Board holder 56 Harness 61 Lower case 62 Upper case 62a Top wall 65 Case safety valve 65a Valve body 65b Stem 66 Tape 70 Filter 70a Opening surface 71 Outer periphery 72 Ventilation section 73 Hole 74 Grid section 79 Outer enclosure shape 80 Gas passage 81 First assembly internal passage 82 Second assembly internal passage 83 Vertical passage 84 Downstream passage T70 Plate thickness H74 Height W74 Width

Claims

1. A battery module comprising: a plurality of battery cells; an outer case housing the plurality of battery cells; an exhaust port provided in the outer case for discharging gas from the outer case; and a filter having a plurality of holes and covering the exhaust port, wherein the filter is plate-shaped, and the plurality of holes penetrate through the thickness direction of the filter and are arranged to fill at least a portion of the opening surface perpendicular to the thickness direction.

2. The battery module according to claim 1, wherein each of the plurality of holes is a convex parallel hexagon.

3. The battery module according to claim 1 or 2, wherein the thickness of the filter is 1 to 5 mm.

4. The battery module according to claim 1 or 2, wherein the filter has a grid portion defining the plurality of holes, and the cross-section of the grid portion is a rectangular shape that is elongated in the thickness direction.

Images