Battery module

Abstract

This battery module comprises: a plurality of battery cells 30 each having an open part 30k from which emissions are discharged; a first insulation part 5 with insulating properties and having a flat plate-like first base part 5k disposed to face the plurality of battery cells 30 and a plurality of open valves 5b which are disposed to face the plurality of open parts 30k, respectively, and each of which is configured by a slit formed in the first base part 5k so as to be opened to a side away from the battery cell 30 in response to the discharge of emissions from the open part 30k; and a second insulation part 6 with insulating properties and having a flat plate-like second base part 6k disposed farther away from the battery cells 30 than the first insulation part 5 in the facing direction in which the open parts 30k and the open valves 5b face each other, and a plurality of through holes 6h which each penetrate the second base part 6k in the facing direction so as to surround the open valves 5b as seen in the facing direction.

Description

Battery module

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

[0002] Patent Document 1 discloses a battery module including a plurality of batteries each having an opening portion for discharging gas generated inside the battery to the outside of the battery, and a case for accommodating the plurality of batteries. The case is partitioned into a housing portion for housing the batteries and an exhaust path for exhausting the gas discharged from the opening portion of the battery to the outside of the case. Between the opening portion of the battery housed in the housing portion and the exhaust path, a plate-like member having a one-way valve that opens only in one direction from the opening portion of the battery toward the exhaust path is disposed. The one-way valve is configured by thinning the plate-like member into an arc shape.

[0003] International Publication No. 2012 / 017586

[0004] In the one-way valve disclosed in Patent Document 1, even if discharges such as gas and molten metal are discharged from the opening portion of the battery, it does not open, and there is a possibility that the discharges cannot be smoothly discharged to the outside of the case. If the discharges cannot be smoothly discharged, the discharges may touch the battery cell, and the battery cell may deteriorate. For this reason, there is a need for a battery module that can improve the protection performance for the battery cell by smoothly discharging the discharges.

[0005] An object of the present disclosure is to provide a battery module capable of improving the protection performance for a battery cell.

[0006] One aspect of the present disclosure provides a battery module comprising: a plurality of battery cells, each having an opening for discharge of waste; a flat plate-shaped first base portion disposed opposite to the plurality of battery cells; an insulating first insulating portion disposed opposite to each of the plurality of openings and having a plurality of opening valves, each composed of slits formed in the first base portion so as to open toward the battery cells in response to the discharge of waste from the openings; a flat plate-shaped second base portion disposed further from the battery cells than the first insulating portion in the opposing direction in which the openings and the opening valves face each other; and an insulating second insulating portion having a plurality of through holes that each penetrate the second base portion in the opposing direction so as to surround the opening valves when viewed in the opposing direction.

[0007] This disclosure provides a battery module that can improve the protection performance for battery cells.

[0008] An exploded perspective view showing a battery module according to the first embodiment. A partial cross-sectional view showing a portion of the cross-section along the line II-II shown in Figure 1. A cross-sectional view showing the vicinity of the positive electrode side of the battery cell shown in Figure 2. A perspective view showing the battery cell, first insulating part, and second insulating part according to the first embodiment. A plan view showing the first insulating part according to the first embodiment. An enlarged view showing the vicinity of the opening valve shown in Figure 5A. A plan view showing the first insulating part and the second insulating part according to the first embodiment. An enlarged view showing the vicinity of the opening valve shown in Figure 6A. A cross-sectional view showing the open state of the opening valve shown in Figure 3.

[0009] A battery module according to one embodiment of the present disclosure comprises: a plurality of battery cells, each having an opening for discharge of waste; a flat plate-shaped first base portion arranged opposite to the plurality of battery cells; an insulating first insulating portion arranged opposite to each of the plurality of openings and having a plurality of opening valves, each composed of slits formed in the first base portion so as to open toward the side away from the battery cells in response to the discharge of waste from the openings; a flat plate-shaped second base portion arranged further from the battery cells than the first insulating portion in the opposing direction in which the openings and the opening valves face each other; and an insulating second insulating portion having a plurality of through holes that each penetrate the second base portion in the opposing direction so as to surround the opening valves when viewed in the opposing direction.

[0010] According to the above configuration, when viewed in the opposing direction, the release valve of the first insulating part is surrounded by the through hole of the second insulating part. Therefore, the discharged material that passes through the opening formed when the release valve is opened can be moved by the second base of the second insulating part to a space partitioned from the space where the battery cells are arranged. This prevents the discharged material from coming into contact with the battery cell that discharged the material (hereinafter referred to as the trigger cell) and battery cells adjacent to the trigger cell, thereby suppressing the deterioration of the battery cells. In other words, according to the above configuration, the protective performance for the battery cells can be improved.

[0011] The thickness of the first base may be less than the thickness of the second base.

[0012] With the above configuration, the release valve can be opened more easily, allowing for the smooth discharge of waste.

[0013] The first base may be made of a material with a lower Young's modulus than the second base.

[0014] With the above configuration, the release valve can be opened more easily, allowing for the smooth discharge of waste.

[0015] The opening valve may have a circular cover portion that is positioned inside the through-hole when viewed in the opposing direction and has a portion that is partially cut out, and a notch portion that extends radially inward from the cover portion.

[0016] With the above configuration, the release valve opens evenly, and a wide opening is ensured when the release valve opens. As a result, waste can be discharged smoothly.

[0017] The first insulating portion may further have a plurality of tabs that extend radially outward from the cover portion of each of the plurality of opening valves.

[0018] With the above configuration, it is possible to prevent waste from entering the space where the battery cells are located through the slits that make up the opening valve.

[0019] A battery module according to another embodiment of the present disclosure comprises a plurality of battery cells, each having an opening for discharging waste, and an insulating portion, the insulating portion comprising a flat base portion disposed opposite to the plurality of battery cells, and a plurality of release valves disposed opposite to each of the plurality of openings, each consisting of a slit formed in the base portion so as to open away from the battery cells in response to the discharge of waste from the openings, the release valve comprising a circular cover portion with a portion cut out, and a notch portion extending radially inward from the cover portion, and the insulating portion having such a release valve.

[0020] With the above configuration, the release valve opens evenly, and a wide opening is ensured when the release valve opens. As a result, waste can be discharged smoothly.

[0021] The insulating portion may further have a plurality of tabs that extend radially outward from the cover portion of each of the plurality of opening valves.

[0022] The above configuration makes it possible to prevent waste from entering the space where the battery cells are located.

[0023] 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.

[0024] 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.

[0025] Referring to Figure 1, the battery module 1 according to the first embodiment comprises an outer case 2, a battery assembly 3, a current collection structure 4, a first insulating part 5 (an example of an insulating part), a second insulating part 6, and a heat-resistant member 7.

[0026] The outer casing 2 is rectangular in shape and consists of a base component 21 and a cover component 22. The base component 21 is flat, and the cover component 22 is a box-shaped member that is open on one side. The base component 21 covers the open portion of the cover component 22, creating a space inside the outer casing 2. The battery assembly 3, the current collection structure 4, the first insulating part 5, the second insulating part 6, and the heat-resistant member 7 are housed in this space inside the outer casing 2 (see Figure 2).

[0027] The battery assembly 3 has a plurality of battery cells 30, a first holder component 31, and a second holder component 32. In this embodiment, the battery assembly 3 has six cylindrical lithium-ion secondary batteries as the plurality of battery cells 30. However, the battery cells 30 may be secondary batteries other than lithium-ion batteries, such as all-solid-state batteries, or batteries other than cylindrical batteries, such as prismatic batteries. Also, the number of battery cells 30 may be more than six.

[0028] The battery cell 30 has an outer casing 30a and a sealing plate 30b. The outer casing 30a is a bottomed cylindrical shape with an opening at one end in the axial direction, and houses the electrode body and electrolyte.

[0029] The sealing plate 30b is positioned at one end in the axial direction and seals the opening at that end in the axial direction via an insulating material.

[0030] The sealing plate 30b has an opening 30k as part of the safety mechanism of the battery cell 30. Gas, molten metal, and other waste are discharged from the opening 30k. The gas is, for example, hydrogen or carbon dioxide, and the molten metal is, for example, molten metal obtained by melting metals such as nickel, cobalt, manganese, aluminum, copper, or lithium. In this embodiment, the opening 30k is circular when viewed along the axial direction.

[0031] Hereinafter, the side of the battery cell 30 where the sealing plate 30b is located will be referred to as the "upper side" and the opposite side in the axial direction as the "lower side," and this direction will be called the vertical direction Z. Furthermore, the longitudinal direction of the outer case 2 along the vertical direction Z will be referred to as the left-right direction X, and the direction perpendicular to the vertical direction Z and the left-right direction X will be referred to as the front-back direction Y. Note that the vertical direction Z is just one example of opposing directions.

[0032] In this embodiment, a first electrode, serving as the positive electrode, is provided on the upper side of the battery cell 30, and a second electrode, serving as the negative electrode, is provided on the lower side of the battery cell 30. The positive and negative electrodes may be reversed.

[0033] Each of the first holder component 31 and the second holder component 32 is made of an insulating material such as synthetic resin. The first holder component 31 and the second holder component 32 are arranged to sandwich the battery cell 30 in the vertical direction Z. By integrating the first holder component 31 and the second holder component 32, a holder 33 that accommodates multiple battery cells 30 is formed (see also Figure 2).

[0034] Multiple battery cells 30 are aligned in the XY plane, which is perpendicular to the vertical direction Z. In this embodiment, the multiple battery cells 30 are arranged in two rows along the front-to-back direction Y, with three rows of battery cells 30 aligned along the left-to-right direction X. Battery cells 30 adjacent in the front-to-back direction Y are placed between adjacent battery cells 30 in the left-to-right direction X. The spacing between adjacent battery cells 30 is constant.

[0035] The first holder component 31 has a rectangular parallelepiped-shaped base 31b that is thinner (has a shorter length in the vertical direction Z) than the second holder component 32. Multiple first recesses 31r are formed in the base 31b.

[0036] The first recess 31r is provided according to the number of battery cells 30. Furthermore, the first recess 31r is formed according to the shape and size of the battery cell 30, and the lower portion of the battery cell 30 is housed in the first recess 31r.

[0037] As shown in Figure 2, the base 31b has a bottom wall 31d, and the bottom wall 31d has a plurality of first holder holes 31h that penetrate the bottom wall 31d in the vertical direction Z. The first holder holes 31h are provided for each first recess 31r.

[0038] The first holder hole 31h is formed to include a region facing the second electrode of the battery cell 30 housed in the first recess 31r. For example, the first holder hole 31h is formed to be coaxial with the second electrode of the battery cell 30. The second electrode of the battery cell 30 housed in the first recess 31r is electrically connected to the current collection structure 4 via the first holder hole 31h.

[0039] As shown in Figure 1, the second holder component 32 has a rectangular parallelepiped block 32b. Multiple second recesses 32r are formed in the block 32b.

[0040] The second recess 32r is provided according to the number of battery cells 30. Furthermore, the second recess 32r is formed to face the first recess 31r in the vertical direction Z. In other words, the second recess 32r is formed according to the shape and size of the battery cell 30, and the upper portion of the battery cell 30 is housed in the second recess 32r.

[0041] Block 32b has a top wall 32t, and the top wall 32t has a plurality of second holder holes 32h that penetrate the top wall 32t in the vertical direction Z. The second holder holes 32h are provided for each second recess 32r.

[0042] The second holder hole 32h is formed to include a region facing the first electrode and the opening 30k of the battery cell 30 housed in the second recess 32r. For example, the second holder hole 32h is formed to be coaxial with the first electrode and the opening 30k (sealing plate 30b) of the battery cell 30. The first electrode of the battery cell 30 housed in the second recess 32r is electrically connected to the current collection structure 4 via the second holder hole 32h (see Figure 2).

[0043] The current collector structure 4 has a first conductive plate 41 and a second conductive plate 42, and connects a plurality of battery cells 30 in parallel. The first conductive plate 41 and the second conductive plate 42 are arranged to face each other in the vertical direction Z with the holder 33 interposed therebetween.

[0044] The first conductive plate 41 is disposed below the first holder component 31 (see FIG. 2). The first conductive plate 41 has a first conductive base portion 41k, a plurality of first conductive holes 41h, and a plurality of first lead wires 41r.

[0045] The first conductive base portion 41k is in the shape of a rectangular flat plate as viewed along the vertical direction Z and has a plane orthogonal to the vertical direction Z. The first conductive base portion 41k is a conductive member such as a metal like copper.

[0046] The first conductive holes 41h penetrate the first conductive base portion 41k along the vertical direction Z. The number and arrangement of the first conductive holes 41h correspond to the number and arrangement of the battery cells 30.

[0047] The first lead wire 41r extends from the edge constituting the first conductive hole 41h, and as shown in FIG. 2, its tip contacts the second electrode of the battery cell 30 through the first holder hole 31h. Thereby, the second electrode of the battery cell 30 and the first conductive plate 41 are electrically connected.

[0048] The second conductive plate 42 is disposed above the second holder component 32 (see FIG. 2). The second conductive plate 42 has a second conductive base portion 42k, a plurality of second conductive holes 42h, and a plurality of second lead wires 42r.

[0049] The second conductive base portion 42k is in the shape of a rectangular flat plate as viewed along the vertical direction Z and has a plane orthogonal to the vertical direction Z. Note that the outer shape of the second conductive base portion 42k and the outer shape of the first conductive base portion 41k are the same in the vertical direction Z. The second conductive base portion 42k is a conductive member such as a metal like copper.

[0050] The second conductive holes 42h penetrate the second conductive base portion 42k along the vertical direction Z. The number and arrangement of the second conductive holes 42h correspond to the number and arrangement of the battery cells 30.

[0051] The second lead wire 42r extends from the edge forming the second conductive hole 42h, and as shown in Figure 2, its tip contacts the first electrode of the battery cell 30 through the second holder hole 32h. This electrically connects the first electrode of the battery cell 30 and the second conductive plate 42.

[0052] Multiple battery cells 30 are connected in parallel by electrically connecting the first electrode of each of the multiple battery cells 30 to the second conductive plate 42, and by electrically connecting the second electrode of each battery cell 30 to the first conductive plate 41.

[0053] The first insulating portion 5 is positioned above the second conductive plate 42. In the vertical direction Z, the first insulating portion 5 faces the multiple battery cells 30, sandwiching the second conductive plate 42 and the second holder component 32.

[0054] As shown in Figure 1, the first insulating portion 5 has a first insulating base 5k (an example of the first base and base) and a plurality of opening valves 5b.

[0055] The first insulating base 5k is a flat plate whose external shape, when viewed along the vertical direction Z, is the same as that of the second conductive plate 42. As shown in Figure 3, the first insulating base 5k is placed on top of the second conductive plate 42.

[0056] The first insulating base 5k is positioned to face the plurality of battery cells via the second conductive plate 42 and the second holder component 32. Specifically, as shown in Figure 4, the first insulating base 5k is positioned to include all of the plurality of battery cells 30 when viewed in the vertical direction Z.

[0057] The first insulating base 5k is made of an insulating material such as synthetic resin or rubber. In this embodiment, the first insulating base 5k is made of aramid fibers (for example, meta-aramid fibers).

[0058] As shown in Figure 5A, each of the multiple opening valves 5b is positioned opposite each of the openings 30k of the multiple battery cells 30.

[0059] As shown in Figure 5B, the opening valve 5b is composed of a slit 50 formed in the first insulating base 5k. In this embodiment, the slit 50 does not penetrate the first insulating base 5k. However, the slit 50 may penetrate the first insulating base 5k.

[0060] The opening valve 5b has a cover portion 51 and a notched portion 53. The cover portion 51 is circular in shape with a portion cut out. The cover portion 51 has two arc portions 52 that form the outer edge of the cover portion 51 and each form a part of the slit 50.

[0061] The two arc portions 52 are arc-shaped when viewed along the vertical direction Z (for example, arcs with a central angle less than 180 degrees and greater than 90 degrees). The two arc portions 52 are spaced apart from each other and face each other in the radial direction DR. In this embodiment, the arc portions 52 are formed such that the center of the arc coincides with the center of the opening portion 30k (sealing plate 30b shown in Figure 1).

[0062] The notched portion 53 extends radially inward from the lid portion 51. The notched portion 53 has two notched linear portions 54 that form the outer edge of the notched portion 53 and each constitute a part of the slit 50.

[0063] Each of the two notched linear portions 54 extends linearly inward in the radial direction DR from one end 52a of each of the two arc portions 52. The tip of each notched linear portion 54 reaches a position inside the battery cell 30, beyond the opening 30k of the battery cell 30. The lengths of the two notched linear portions 54 are equal.

[0064] The opening valve 5b, configured as described above, opens by moving toward the side away from the battery cell 30 (upward) in response to the discharge of waste from the opening 30k of the battery cell 30 (see Figure 7).

[0065] Furthermore, the first insulating section 5 has a plurality of tabs 5t that are connected to each of the plurality of opening valves 5b.

[0066] The tab 5t is connected to the lid 51 and extends radially outward from the lid 51 in the direction DR. The tab 5t has two extensions 56 and a connecting portion 57. The two extensions 56 and the connecting portion 57 form the outer edge of the tab 5t and also form part of the slit 50.

[0067] Each of the two extensions 56 extends linearly outward in the radial direction DR from the other end 52b of each of the two arc sections 52. The lengths of the two extensions 56 are equal, and the connecting portion 57 is connected to the ends of the two extensions 56.

[0068] As shown in Figure 4, the second insulating portion 6 is positioned above the first insulating portion 5. In other words, the second insulating base portion 6k is positioned further away from the battery cell 30 than the first insulating base portion 5k.

[0069] As shown in Figure 3, the second insulating portion 6 faces the multiple battery cells 30 in the vertical direction Z, with the first insulating portion 5, the second conductive plate 42, and the second holder component 32 in between.

[0070] As shown in Figure 1, the second insulating portion 6 has a second insulating base portion 6k (an example of the second base portion) and a plurality of through holes 6h.

[0071] The second insulating base 6k is a flat plate shape with the same external shape as the first insulating base 5k when viewed along the vertical direction Z, and is arranged on top of the first insulating base 5k of the first insulating part 5, as shown in Figure 3. In this embodiment, the second insulating base 6k is arranged in contact with the first insulating base 5k.

[0072] The second insulating base 6k is made of an insulating material such as synthetic resin or rubber. Furthermore, a highly flame-retardant material is selected for the second insulating base 6k.

[0073] In this embodiment, the second insulating base 6k is composed of a mica sheet with a higher Young's modulus than the first insulating base 5k. In other words, the first insulating base 5k is composed of a material with a lower Young's modulus than the second insulating base 6k, such as flame-retardant meta-aramid fiber, such as Nomex®. The Young's modulus of the first insulating base 5k is, for example, 4 GPa, and the Young's modulus of the second insulating base 6k is, for example, 100 GPa.

[0074] Furthermore, the second insulating base 6k is configured to have a larger second moment than the first insulating base 5k. Specifically, as shown in Figure 3, the thickness D1 (length in the vertical direction Z) of the first insulating base 5k is set to be smaller than the thickness D2 (length in the vertical direction Z) of the second insulating base 6k.

[0075] The through-hole 6h penetrates the second insulating base 6k in the vertical direction Z. The through-hole 6h is formed in a shape corresponding to the outer edge of the opening valve 5b so that the cover 51 of the opening valve 5b can pass through. In this embodiment, as shown in Figure 6A, the through-hole 6h is circular when viewed in the vertical direction Z.

[0076] The through-hole 6h is formed to surround the opening valve 5b when viewed along the vertical direction Z. More specifically, the through-hole 6h is provided such that its radius is larger than the radius of the arc portion 52 of the opening valve 5b, and its center coincides with the center of the arc portion 52 when viewed along the vertical direction Z.

[0077] In this embodiment, the radius of the through-hole 6h is formed to be slightly larger than the radius of the arc portion 52, and as shown in Figure 6B, the cover portion 51 and the notched portion 53 are positioned inside the through-hole 6h. On the other hand, a part of the tab 5t (a part of the extension portion 56 and the connecting portion 57) is positioned outside the through-hole 6h. In other words, with the second insulating portion 6 positioned above the first insulating portion 5, the opening valve 5b is exposed from the through-hole 6h, and a part of the tab 5t is covered by the second insulating base portion 6k.

[0078] As shown in Figure 3, the heat-resistant member 7 is positioned above the second insulating portion 6, spaced apart from the second insulating portion 6. The heat-resistant member 7 is made of a material that has heat resistance and insulating properties. In this embodiment, the heat-resistant member 7 is, for example, a mica sheet.

[0079] In the battery module 1 configured as described above, when the internal pressure of the battery cell 30 increases, as shown in Figure 7, the discharged material is discharged from the battery cell 30 (outer casing 30a) through the opening 30k. The internal pressure of the battery cell 30 increases, for example, when a short circuit occurs inside the battery cell 30.

[0080] When waste is discharged, a crack forms in the first insulating base 5k along the slit 50, causing the lid 51 of the opening valve 5b to move away from the battery cell 30 (upwards). The tab 5t bends slightly downwards. The end of the notch 53 that connects to the lid 51 (inside the radial direction DR shown in Figure 5B) moves upwards as the lid 51 moves, while the opposite end (outside the radial direction DR) remains connected to the first insulating base 5k. As a result, the notch 53 tilts between the lid 51 and the first insulating base 5k, supporting the lid 51 from below.

[0081] As described above, when the release valve 5b is opened, an opening 5h having the same shape as the lid portion 51 is formed in the first insulating base portion 5k. This allows the discharged material to pass through the opening 5h, enabling smooth discharge of the material.

[0082] As described above, in the above embodiment, when viewed along the vertical direction Z, the release valve 5b is surrounded by the through hole 6h of the second insulating part 6. Therefore, the discharged material that passes through the opening 5h formed when the release valve 5b is opened can move to a space partitioned from the space where the battery cells 30 are arranged by the second insulating base 6k of the second insulating part 6. This prevents the discharged material from coming into contact with the battery cell 30 that discharged the material (hereinafter referred to as the trigger cell 30) and the battery cells 30 adjacent to the trigger cell 30, thereby suppressing the deterioration of the battery cells 30. In other words, according to this embodiment, the protective performance for the battery cells 30 can be improved.

[0083] In the above embodiment, a two-layer insulating structure is formed by overlapping the first insulating part 5 and the second insulating part 6. Therefore, even if the first insulating part 5 is damaged (e.g., melted) by high-temperature exhaust, the battery cell 30 can be protected by the second insulating part 6. Furthermore, the two-layer insulating structure also improves the degree of freedom in selecting the material and dimensions (thickness D1) of the first insulating part 5.

[0084] Furthermore, in the above embodiment, the thickness D1 of the first insulating base 5k is smaller than the thickness D2 of the second insulating base 6k, and the Young's modulus of the first insulating part 5 (first insulating base 5k) is smaller than the Young's modulus of the second insulating base 6k. Therefore, compared to a configuration in which, for example, an opening valve 5b is provided on the second insulating base 6k, the opening valve 5b opens more easily (operates stably), and discharged material can be discharged smoothly. Consequently, the protective performance for the battery cell 30 can be improved.

[0085] Furthermore, in the above embodiment, the lid portion 51 is supported by the notched portion 53, which prevents the lid portion 51 from tilting (shifting). This allows for a wider opening 5h to be formed when the release valve 5b is opened. As a result, discharged material can be discharged smoothly. This prevents the accumulation of discharged material on the trigger cell 30, thereby suppressing the deterioration of the trigger cell 30. In addition, it prevents the retention of high-heat discharged material on and around the trigger cell 30, thereby suppressing the deterioration of the trigger cell 30 and the battery cells 30 adjacent to the trigger cell 30. In other words, the protective performance for the battery cells 30 can be improved.

[0086] Furthermore, in the above embodiment, the tab 5t extends radially outward from the lid 51 in the DR direction and is covered by the second insulating base 6k. This prevents waste from entering the space (second recess 32r) where the battery cell 30 is located through the slit 50 that constitutes the opening valve 5b. This protects the battery cell 30.

[0087] While embodiments have been described above, various modifications are possible to the above configuration within the scope of the spirit of this disclosure.

[0088] For example, in the above embodiment, the case in which the first insulating base 5k is made of aramid fibers was described, but the first insulating base 5k may be made of a material other than aramid fibers. For example, the first insulating base 5k and the second insulating base 6k may be made of the same material.

[0089] In the above embodiment, the case where the thickness D1 of the first insulating base 5k is smaller than the thickness D2 of the second insulating base 6k was described. However, any configuration that makes it easier to open the opening valve 5b than if the opening valve 5b were provided on the second insulating base 6k is acceptable, and the thickness D1 of the first insulating base 5k may be the same as (substantially the same as) the thickness D2 of the second insulating base 6k.

[0090] In the above embodiment, the first insulating base 5k is made of a material with a lower Young's modulus than the second insulating base 6k. However, as long as the opening valve 5b is easier to open than if the opening valve 5b were provided on the second insulating base 6k, the first insulating base 5k may be made of a material with the same (substantially the same) Young's modulus as the second insulating base 6k.

[0091] In the above embodiment, the opening 30k was circular when viewed along the vertical direction Z, but the shape of the opening 30k can be appropriately changed to a rectangular shape, an elliptical shape, or other shapes depending on the shape of the battery cell 30. Also, the shape of the lid 51 can be appropriately changed according to the shape of the battery cell 30 (opening 30k).

[0092] In the above embodiment, the first insulating portion 5 had a tab 5t, but the tab 5t may be omitted.

[0093] This disclosure may include the following embodiments: (Embodiment 1) A battery module comprising: a plurality of battery cells, each having an opening for discharge of waste; a flat plate-shaped first base portion disposed opposite to the plurality of battery cells; and a plurality of insulating first insulators disposed opposite to each of the plurality of openings, each having a plurality of opening valves formed in the first base portion so as to open toward the side away from the battery cells in response to the discharge of waste from the openings; and a flat plate-shaped second base portion disposed further from the battery cells than the first insulator in the opposing direction in which the openings and the opening valves face each other; and an insulating second insulator having a plurality of through holes that each penetrate the second base portion toward the opposing direction so as to surround the opening valves when viewed in the opposing direction. (Embodiment 2) The battery module according to Embodiment 1, wherein the thickness of the first base portion is less than the thickness of the second base portion. (Embodiment 3) The battery module according to Embodiment 1 or 2, wherein the first base portion is made of a material with a smaller Young's modulus than the second base portion. (Aspect 4) The battery module according to any one of aspects 1 to 3, wherein the opening valve has a circular cover portion which is positioned inside the through hole when viewed in the opposing direction and has a portion that is partially cut out, and a notch portion which extends radially inward from the cover portion. (Aspect 5) The battery module according to aspect 4, wherein the first insulating portion further has a plurality of tabs which extend radially outward from each of the cover portions of the plurality of opening valves. (Aspect 6) A battery module comprising: a plurality of battery cells, each having an opening for discharging waste; an insulating part, the insulating part comprising: a plurality of flat bases arranged opposite to the plurality of battery cells; and a plurality of opening valves, each composed of slits formed in the bases, arranged opposite to each of the plurality of openings, and opening toward the side away from the battery cells in response to the discharge of waste from the openings, the opening valve comprising: a circular cover portion with a portion cut out in part; and a notch portion extending radially inward from the cover portion; and the insulating part having;

[0094] 1 Battery module 2 Outer casing 3 Battery assembly 4 Current collection structure 5 First insulating part (example of insulating part) 5b Opening valve 5h Opening 5k First insulating base (example of first base) 5t Tab 6 Second insulating part 6h Through hole 6k Second insulating base (example of second base) 7 Heat-resistant material 21 Base part 22 Cover part 30 Battery cell 30a Outer casing 30b Sealing plate 30k Opening part 31 First holder part 31b Base 31d Bottom wall 31h First holder hole 31r First recess 32 Second holder part 32b Block 32h Second holder hole 32r Second recess 32t Top wall 33 Holder 41 First conductive plate 41h First conductive hole 41k First conductive base 41r First lead wire 42 Second conductive plate 42h Second conductive hole 42k Second conductive base 42r Second lead wire 50 Slit 51 Cover 52 Arc portion 52a One end 52b Other end 53 Notched portion 54 Notched linear portion 56 Extension portion 57 Connection portion DR Radial direction X Left / right direction Y Front / back direction Z Up / down direction

Claims

1. A battery module comprising: a plurality of battery cells, each having an opening for discharge of waste; a flat plate-shaped first base portion arranged opposite to the plurality of battery cells; and an insulating first insulating portion arranged opposite to each of the plurality of openings, each having a plurality of opening valves formed by slits in the first base portion so as to open toward the side away from the battery cells in response to the discharge of waste from the openings; and a flat plate-shaped second base portion arranged further away from the battery cells than the first insulating portion in the opposing direction in which the openings and the opening valves face each other; and an insulating second insulating portion having a plurality of through holes that each penetrate the second base portion in the opposing direction so as to surround the opening valves when viewed in the opposing direction.

2. The battery module according to claim 1, wherein the thickness of the first base is smaller than the thickness of the second base.

3. The battery module according to claim 1 or 2, wherein the first base is made of a material having a lower Young's modulus than the second base.

4. The battery module according to claim 1 or 2, wherein the release valve is positioned inside the through hole when viewed in the opposing direction and has a circular cover portion which is partially cut out, and a notch portion which extends radially inward from the cover portion.

5. The battery module according to claim 4, wherein the first insulating portion further comprises a plurality of tabs each extending radially outward from the cover portion of each of the plurality of opening valves.

6. A battery module comprising: a plurality of battery cells, each having an opening for discharging waste; an insulating portion, the insulating portion comprising: a flat base portion arranged opposite to the plurality of battery cells; and a plurality of release valves, each arranged opposite to each of the plurality of openings and configured with slits formed in the base portion so as to open away from the battery cells in response to the discharge of waste from the openings, the release valve comprising: a circular cover portion with a portion cut out in part; and a notch portion extending radially inward from the cover portion; and the insulating portion comprising:

7. The battery module according to claim 6, wherein the insulating portion further comprises a plurality of tabs each extending radially outward from the cover portion of each of the plurality of opening valves.

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