Battery tray

Abstract

This battery storage tray (1) is provided with: a bottom plate (65) which supports a plurality of batteries (10); a side wall which extends from the outer peripheral part of an upper surface (31) of the bottom plate (65) in the thickness direction of the bottom plate (65) so as to surround a stage surface (32) for the plurality of batteries (10) in the upper surface (31), thereby defining a battery storage space, in which the plurality of batteries (10) are contained, together with the bottom plate (65); and a plate-like permanent magnet (35) which is affixed to at least a part of a bottom surface (65a) of the bottom plate (65).

Description

[Technical Field]

[0001] The present disclosure relates to a battery receiving tray. [Background technology]

[0002] A conventional battery housing tray is described in Patent Document 1. This battery housing tray includes a partition body having a plurality of compartments for housing, and an outer frame body that is arranged to surround the periphery of the partition body, and is capable of housing a plurality of batteries at the same time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-173567 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, batteries have been used as power sources for electric vehicles (EVs) and large-scale energy storage facilities, and research and development into increasing their capacity is progressing. Furthermore, in the event that such high-capacity batteries experience abnormal heat generation and excessive internal pressure, the sealing plate or a portion of the bottom breaks to release (vent) the high-temperature gas to the outside, thereby enhancing safety. Furthermore, when transporting batteries, for example, multiple battery housing trays containing multiple batteries closely packed together are stacked on top of each other, and these multiple battery housing trays are moved simultaneously, allowing efficient transport of multiple batteries.

[0005] In this context, if one of the batteries housed in a battery housing tray were to abnormally heat up while the batteries were being transported, it would be extremely significant to improve safety if the effects of that abnormal heat could be limited to affect other batteries housed in the same battery housing tray as the battery in question, or batteries housed in other battery housing trays.

[0006] Therefore, the object of the present disclosure is to provide a battery storage tray that can store multiple batteries closely together and stack them, and in which, even if one battery generates abnormal heat, the effects of that abnormal heat are less likely to affect other batteries. [Means for solving the problem]

[0007] In order to solve the above problems, the battery storage tray of the present disclosure comprises a bottom plate that supports multiple batteries, side walls that extend in the thickness direction of the bottom plate from the outer edge of the top surface of the bottom plate to surround the surface on the top surface where the multiple batteries are placed, and that together with the bottom plate define a battery storage space that stores the multiple batteries, and a plate-shaped permanent magnet fixed to at least a portion of the bottom surface of the bottom plate. [Effects of the Invention]

[0008] According to the battery housing tray of the present disclosure, when multiple batteries are closely housed and stacked, even if one battery generates abnormal heat, the effects of that abnormal heat are less likely to affect other batteries. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a side view of a battery housing tray according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is a partially enlarged plan view of the battery housing tray as viewed from above in the thickness direction, illustrating an example of the structure of a cylindrical battery housing section in the battery housing space. [Figure 3] 3 is a schematic cross-sectional view of the battery housing tray, with cylindrical batteries housed in each housing section, taken along line AA in FIG. 2. FIG. [Figure 4] FIG. 1(a) is a schematic diagram showing the battery accommodating trays of Example 1 stacked in three layers, FIG. 1(b) is a schematic diagram showing the battery accommodating trays of Example 2 stacked in three layers, and FIG. 1(c) is a schematic diagram showing the battery accommodating trays of the comparative example stacked in three layers. [Figure 5]FIG. 10 is a schematic diagram illustrating the process leading to the spread of fire in a test in which a trigger battery in a comparative example of three stacked battery housing trays was forcibly ignited. [Figure 6] FIG. 10 is a schematic diagram illustrating the process by which the flame in the trigger battery was extinguished without spreading to fire in a test in which the trigger battery was forcibly ignited in three-tiered battery housing trays according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that, when multiple embodiments or variations are included below, it is assumed from the outset that new embodiments can be constructed by appropriately combining their characteristic features. In the following examples, the same components are denoted by the same reference numerals in the drawings, and redundant explanations will be omitted. The drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match.

[0011] In the following description, for convenience of explanation, the battery insertion side in the height direction may be referred to as the upper side or top in the height direction, and the battery receiving side in the height direction may be referred to as the lower side or bottom in the height direction. In the following embodiment, a battery housing tray 1 is described as having housing sections 15 arranged in a matrix, and the housing sections 15 have a shape suitable for housing cylindrical batteries 10. Here, the X direction is the row direction of the housing sections 15 arranged in a matrix, the Y direction is the column direction of the housing sections 15 arranged in a matrix, and the Z direction is the height direction of the battery housing tray 1. The X direction, Y direction, and Z direction are perpendicular to one another.

[0012] In the battery housing tray of the present disclosure, the housing section may have a shape suitable for housing prismatic batteries, and the battery housing tray may be designed to house prismatic batteries. Alternatively, in the battery housing tray of the present disclosure, the housing section may have a shape that can house both cylindrical and prismatic batteries, and the battery housing tray may be capable of housing both cylindrical and prismatic batteries. Furthermore, the battery housing tray of the present disclosure does not need to have multiple compartments, and may have a structure that allows adjacent batteries to come into contact with each other. Furthermore, among the components described below, components that are not recited in the independent claims that represent the superordinate concept are optional components and are not required components.

[0013] FIG. 1 is a side view of a battery housing tray 1 according to one embodiment of the present disclosure, and FIG. 2 is a partially enlarged plan view of the battery housing tray 1 as viewed from above in the thickness direction (corresponding to the Z direction) of the bottom plate 65, illustrating the structure of the housing section 15 for a cylindrical battery 10 (see FIG. 3) in the battery housing space 5. In this embodiment, the battery housing tray 1 has a substantially rectangular shape when viewed from above in the Z direction, but the shape of the battery housing tray in plan view is not limited to a rectangle and may be any shape. The battery housing tray 1 is formed of a resin material such as polyimide, polyphenylene ether, polyphenylene sulfide, or polycarbonate, but may also be formed of a metal material such as stainless steel.

[0014] As shown in FIG. 1, the battery housing tray 1 includes a plate-shaped mounting portion 20 that supports cylindrical batteries (hereinafter simply referred to as batteries) 10, and sidewalls 60. The sidewalls 60 extend in the Z direction from the substantially rectangular outer edge of the upper surface 31 (see FIG. 2) of the mounting portion 20 to surround the entire periphery (or substantially the entire periphery) of the mounting surface 32 (see FIG. 2) for the batteries 10 on the upper surface 31. The sidewalls 60, in combination with the mounting portion 20, define a battery housing space 5 that houses multiple batteries 10. As shown in FIG. 1, the sidewalls 60 have multiple windows 61 spaced apart around the periphery. Each window 61 penetrates the sidewall 60 in a direction perpendicular to the Z direction. The windows 61 are provided to, for example, reduce the material cost and weight of the battery housing tray 1, and allow the storage state of the batteries 10 to be checked from the side when stacking the battery housing trays 1 to transport a large number of batteries 10. The battery housing tray of the present disclosure does not necessarily have to have a window portion.

[0015] As shown in FIG. 2 , the battery housing space 5 has multiple housing sections 15, each of which houses a battery 10 and is spaced apart from one another. The multiple housing sections 15 are arranged in a matrix as described above, and each housing section 15 has four battery support sections 16 spaced apart. The four battery support sections 16 are protrusions that protrude upward in the Z direction from the top surface 31. The battery support sections 16 support the side of the battery 10 housed in the housing section 15 at four locations positioned at approximately equal intervals in the circumferential direction, thereby restricting movement of the battery 10 in the X and Y directions. The battery housing tray 1 has a through-hole (cylindrical hole) 37 extending in the Z direction at the center of the bottom of each housing section 15. This through-hole 37 is provided for inserting a terminal for charging the battery 10 housed in the battery housing tray 1, allowing the battery 10 to be charged while housed in the battery housing tray 1.

[0016] The structure of the housing section is not limited to the structure shown in Fig. 2, and any structure that can restrict the movement of the battery may be used. Alternatively, as described above, the battery housing tray does not have to have multiple compartments, and may have a structure that allows adjacent batteries to come into contact with each other within the battery housing space. Furthermore, the battery housing tray does not have to have a through-hole in the mounting section, and may have a structure that prevents the batteries 10 housed in the battery housing tray 1 from being recharged.

[0017] 3 is a schematic cross-sectional view of the battery housing tray 1, taken along line AA in FIG. 2, in which batteries 10 are housed in each housing section 15. As shown in FIG. 3, the battery housing tray 1 includes a main body 25, a plate-shaped permanent magnet 35, and insulating resin 45. The main body 25 has side walls 60 (see FIG. 1) and a bottom plate 65, and is integrally formed by, for example, injection molding. The mounting section 20 includes the bottom plate 65 of the main body 25, the permanent magnet 35, and insulating resin 45. The shapes of the permanent magnet 35 and the insulating resin 45 in a plan view substantially match the shape of the bottom plate 65 in a plan view.

[0018] The upper surface of the permanent magnet 35 is fixed to the entire bottom surface 65a of the bottom plate 65 using a fixing means such as an adhesive, and the insulating resin 45 is provided to cover the entire bottom surface 35a of the permanent magnet 35. The insulating resin 45 is preferably made of a resin with excellent heat resistance, such as PTFE (polytetrafluoroethylene). The bottom plate 65, the permanent magnet 35, and the insulating resin 45 have through holes 65b, 35b, and 45a whose cross sections are identical to the cross section of the through hole 37. The through hole 65b, the through hole 35b, and the through hole 45a are stacked in this order from above in the Z direction. The through hole 65b, the through hole 35b, and the through hole 45a together form the through hole 37. The permanent magnet 35 has an overlapping portion 35c for each of the multiple storage sections 15 that overlaps at least a portion of the storage section 15 when viewed from the Z direction.

[0019] Next, the excellent effects achieved by the battery housing tray of the present disclosure will be described, and a fire spread test to confirm these effects and the test results will be described.

[0020] The inventors stacked three battery housing trays, each housing the largest battery it could accommodate, and conducted a fire spread test on three different battery housing trays, specifically the battery housing tray of Example 1, the battery housing tray of Example 2, and the battery housing tray of the comparative example, to investigate the extent of the effect of intentionally igniting and venting one of the batteries housed in the middle battery housing tray.

[0021] [Battery Storage Tray of Example 1] As the battery accommodating tray of Example 1, the battery accommodating tray 1 described in detail with reference to Figures 1 to 3 was used, and the battery accommodating tray 1 was stacked in three layers as shown in Figure 4(a), and the test was carried out.

[0022] [Battery Storage Tray of Example 2] As the battery accommodating tray of Example 2, a battery accommodating tray 101 was used, which differed from the battery accommodating tray 1 of Example 1 only in that the permanent magnet 135 was not coated with insulating resin, and the battery accommodating trays 101 were stacked in three layers as shown in Figure 4(b) and tested.

[0023] [Battery storage tray of comparative example] As a comparative example, a battery accommodating tray 201 was used, which differed from the battery accommodating tray 1 of Example 1 only in that it did not have a permanent magnet or insulating resin, and the battery accommodating trays 201 were stacked in three layers as shown in Figure 4(c) and tested.

[0024] <Battery construction> The battery used in the fire spread test was fabricated as follows.

[0025] [Preparation of positive electrode plate] The positive electrode active material is lithium nickel oxide (LiNi 0.88 Co 0.09 Al 0.03O2) was used. Then, 100 parts by mass of the positive electrode active material, 1 part by mass of acetylene black as a conductive agent, and 0.9 parts by mass of polyvinylidene fluoride (PVDF) as a binder were mixed in a solvent of N-methylpyrrolidone (NMP) to prepare a positive electrode slurry. This positive electrode slurry was uniformly applied to both sides of a 15 μm-thick aluminum foil. Next, the coating film was heat-treated at 100 to 150 °C in a heated dryer to remove the NMP, and then compressed using a roll press. The compressed electrode plate was further heat-treated by contacting it with a roll heated to 200 °C for 5 seconds, and then cut into a thickness of 0.144 mm, width of 62.6 mm, and length of 861 mm to prepare a positive electrode plate.

[0026] [Preparation of negative electrode plate] As the negative electrode active material, 95 parts by mass of graphite powder and 5 parts by mass of silicon oxide were mixed. Then, 100 parts by mass of the negative electrode active material, 1 part by mass of CMC as a thickener, and 1 part by mass of styrene-butadiene rubber as a binder were dispersed in water to prepare a negative electrode slurry. This negative electrode slurry was applied to both sides of an 8 μm thick copper foil negative electrode current collector to form a negative electrode coating. The coating was then dried and compressed to a thickness of 0.160 mm using a roll press. The compressed electrode plate was then cut to a width of 64.2 mm and a length of 959 mm to produce a negative electrode plate.

[0027] [Preparation of non-aqueous electrolyte] A non-aqueous electrolyte solution was prepared by dissolving 1.5 mol / L of LiPF6 in a mixed solvent (volume ratio of FEC:DMC=1:3) consisting of fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC).

[0028] [Cylindrical battery fabrication] An aluminum positive electrode lead was attached to the positive electrode current collector, and a nickel-copper-nickel negative electrode lead was attached to the negative electrode current collector. The positive and negative electrode plates were then wound with a polyethylene separator between them to produce a wound electrode assembly. The outermost periphery of the electrode assembly was covered with the exposed portion of the negative electrode core. Insulating plates were placed above and below the electrode assembly, and the assembly was housed in a battery case with a circular marking on the bottom. The negative electrode lead was welded to the bottom of the battery case, and the positive electrode lead was welded to a sealing plate with an internal pressure-activated safety valve. A nonaqueous electrolyte was then poured into the battery case. injection The open end of the battery case was then crimped to a sealing plate via a gasket to produce a non-aqueous electrolyte secondary battery. The battery had a capacity of 4200 mAh.

[0029] <Spread of fire test> The above-mentioned batteries were housed in each battery housing tray, and the battery housing trays were stacked in three tiers. NiCr wire was wound around one of the batteries housed in the middle battery housing tray of the three-tier structure, and a large current was applied to the NiCr wire, causing resistance heating and forcing the battery to ignite. Hereinafter, this forcibly ignited battery will be referred to as the trigger battery. The trigger battery is the battery with the symbol 10T, indicated by the diagonal lines in Figures 4(a) to (c). In the test, after the trigger battery 10T ignited, observations were made to determine whether the flame in the trigger battery died down or the batteries surrounding the trigger battery caught fire.

[0030] [Test Results] [Table 1]

[0031] The test was conducted three times for each battery housing tray 1, 101, and 201. The test results are shown in Table 1. In Table 1, ◯ indicates that the flame of the trigger battery 10T was extinguished without fire spreading, and × indicates that fire spread to the batteries surrounding the trigger battery. As shown in Table 1, no fire spread occurred in the test using the battery housing tray 1 of Example 1. On the other hand, in the comparative example using the battery housing tray 201 without a magnet (see Figure 4(c)), fire spread occurred in two of the three tests.

[0032] More detailed observations revealed that in a test using the comparative battery housing tray 201, the fire spread in the process shown in Figure 5. Note that in Figures 5 and 6, areas of the battery with high temperatures are shown in gray. Specifically, in a test using the comparative battery housing tray 201, when a trigger battery 10T with an engraved mark on the bottom of the can ignited and the can bottom vented, the trigger battery 10T flew upward in the Z direction, collided with the bottom of the upper battery housing tray 101a, and bounced off, as shown in Figure 5(a). The flame from the trigger battery 10T then continued to hit the middle battery housing tray 101b, and the high-temperature trigger battery 10T continued to contact the middle battery housing tray 101b, resulting in the middle battery housing tray 101b catching fire, as shown in Figure 5(b). Subsequently, the middle battery housing tray 101b melted, and as shown in Figure 5(c), the trigger battery 10T fell under its own weight through the melted part of the middle battery housing tray 101b onto the lower battery housing tray 101c, causing the multiple batteries 10F housed in the lower battery housing tray 101c to catch fire.

[0033] In contrast, in a test using the battery housing tray 1 of Example 1, the flame of the trigger battery 10T was extinguished through the process shown in Figure 6. Specifically, when the trigger battery 10T, which had an engraved mark on the bottom of the can, ignited and the can bottom vented, the trigger battery 10T flew upward in the Z direction and was attracted to the permanent magnet 35 of the upper battery housing tray 1a, as shown in Figure 6(a). Then, as shown in Figure 6(b), the trigger battery 10T remained floating above the top surface 31b of the middle battery housing tray 1b. Due to this action, the bottom side of the trigger battery 10T, which was the hottest and from which the flame was erupting, did not come into contact with any of the battery housing trays 1a, 1b, or 1c. Although the temperature of the batteries 10K around the trigger battery 10T rose, none of the batteries 10K ignited. The flame of the trigger battery 10T then extinguished, preventing it from spreading to fire.

[0034] In other words, in the battery housing tray 1 of Example 1, the permanent magnet 35 installed at the bottom attracted the ignited trigger battery 10T to the bottom of the upper battery housing tray 1a, preventing the middle battery housing tray 1b from burning and melting and the trigger battery 10T from falling onto the lower battery housing tray 1c. As a result, the fire did not spread and the time it took to extinguish was short.

[0035] Furthermore, in Example 2, in which only the permanent magnet 135 (see FIG. 4(b)) was placed on the bottom side of the battery accommodating tray 101 and the bottom side of the permanent magnet 135 was not covered with insulating resin, no fire spread occurred. However, the heat loss of the battery accommodating tray 101 after the test was greater than in Example 1, and multiple batteries in the battery accommodating tray 101 vented. This is thought to be because when the trigger battery 10T ignited, the impact caused the surrounding batteries to fly up and be attracted to the bottom of the upper battery accommodating tray 101, causing a short circuit on the sealing body side of the battery via the permanent magnet 135. The short-circuited battery vented, causing the electrolyte to leak, which intensified the fire.

[0036] The above test results confirmed that when stacking battery housing trays that house batteries with can-bottom markings, by using a battery housing tray with the permanent magnet of the present disclosure placed at the bottom, even if one of the batteries housed in the battery housing tray abnormally heats up, the effects of that abnormal heat on other batteries can be prevented.

[0037] As is clear from this discussion, the magnetic force of the permanent magnet in each battery housing tray must be set to a level where, in a stack of multiple battery housing trays, the batteries housed in a lower battery housing tray are not attracted to the permanent magnet installed in the battery housing tray one level above. Also, the magnetic force of the permanent magnet in each battery housing tray must be set to a level where a battery ejected upward due to a fire can be attracted by the magnet in the battery housing tray one level above.

[0038] [Configuration of Cylindrical Battery of the Present Disclosure and Its Actions and Effects] As described above, the battery housing tray 1 of the present disclosure comprises a bottom plate 65 that supports multiple batteries 10, a side wall 60 that extends in the thickness direction of the bottom plate 65 from the outer edge of the top surface 31 of the bottom plate 65 to surround the mounting surface 32 on the top surface 31 for the multiple batteries 10, and that, together with the bottom plate 65, defines a battery housing space 5 that houses the multiple batteries 10, and a plate-shaped permanent magnet 35 fixed to at least a portion of the bottom surface 65a of the bottom plate 65.

[0039] According to the present disclosure, when multiple battery housing trays 1 are stacked and multiple batteries 10 are housed in each battery housing space 5, even if the bottom of one battery 10 vents and the battery 10 jumps up, the battery 10 can be attracted by the permanent magnet 35 of the upper battery housing tray 1. This significantly reduces the impact of high-temperature gas spewing from below the battery 10 on the battery housing tray 1 and other batteries 10, greatly improving safety during transport of the batteries 10.

[0040] [Preferable cylindrical battery configuration and its effects] Furthermore, an insulating resin 45 may be provided to cover at least a part of the bottom surface 35a of the permanent magnet 35.

[0041] With the above configuration, when multiple battery housing trays 1 are stacked and multiple batteries 10 are housed in each battery housing space 5, even if the impact of the vent on the bottom of a battery 10 causes surrounding batteries 10 to fly up and be attracted to the bottom of an upper battery housing tray 1, it is possible to prevent a short circuit on the sealing body side of the battery 10 via the permanent magnet 35. This prevents a short-circuited battery from venting and leaking electrolyte, which could cause a fire to intensify, further improving safety.

[0042] Furthermore, a plurality of storage sections 15 each for storing a battery 10 and spaced apart from one another may be provided in the battery storage space 5 .

[0043] The above configuration allows the battery 10 to be positioned in the battery housing tray 1. This makes it easy to identify the fixed position of the permanent magnet 35 that can effectively attract the battery 10.

[0044] Furthermore, the permanent magnet 35 may have an accommodation overlapping portion 35c that overlaps at least a portion of each of the accommodation portions 15 when viewed in the thickness direction.

[0045] According to the above configuration, if the bottom of the can of the battery 10 vents and the battery 10 jumps up, the battery 10 can be reliably attracted by the housing overlap portion 35c of the permanent magnet 35, further improving safety.

[0046] Alternatively, the permanent magnet 35 may be fixed to an area of ​​the bottom surface 35a that includes all of the portions that overlap the multiple housing sections 15 in the thickness direction. The battery housing tray 1 may include an insulating resin 45 that covers the entire bottom surface 35a of the permanent magnet 35.

[0047] With the above configuration, if a battery 10 generates abnormal heat and jumps up, the battery 10 can be reliably attracted by the permanent magnet 35, and other batteries 10 that jump up due to the impact of the jumping up can be reliably prevented from short-circuiting, ensuring complete safety.

[0048] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0049] For example, in the above embodiment, the permanent magnet 35 is fixed to the entire bottom surface 65a of the bottom plate 65, and the entire bottom surface 35a of the permanent magnet 35 is covered with insulating resin 45. However, the magnet may be fixed to only a portion of the bottom surface of the bottom plate, or only a portion of the bottom surface of the magnet may be covered with insulating resin. Alternatively, the bottom surface of the magnet may not be covered with insulating resin.

[0050] Also, a case has been described in which a plurality of storage sections 15, each of which stores a battery 10 and is spaced apart from one another, are provided in the battery storage space 5. A case has also been described in which the permanent magnet 35 has a storage overlapping section 35c that overlaps at least a portion of each of the plurality of storage sections 15 when viewed from the thickness direction of the bottom plate 65. However, the permanent magnet does not have to have a storage overlapping section that overlaps at least a portion of each of the plurality of storage sections when viewed from the thickness direction of the bottom plate.

[0051] In the above test, the trigger battery 10T to be forcibly ignited was a cylindrical battery with a marking for venting engraved on the bottom of the can. According to the inventor's test, when the trigger battery to be forcibly ignited was a cylindrical battery that ruptured on the sealing plate side in the height direction (opposite the bottom side), no fire spread and the flame of the forcibly ignited trigger battery was extinguished in any of the battery housing trays 1 shown in FIG. 4(a), 101 shown in FIG. 4(b), and 201 shown in FIG. 4(c). Therefore, by using the battery housing tray of the present disclosure, safety is ensured regardless of the specifications of the battery being transported. [Explanation of symbols]

[0052] 1, 1a, 1b, 1c, 101, 101a, 101b, 101c battery storage tray, 5 battery storage space, 10, 10F, 10K battery, 10T trigger battery, 15 storage section, 31, 31b upper surface, 32 mounting surface, 35, 135 permanent magnet, 35a bottom surface of permanent magnet, 35c storage overlap section, 45 insulating resin, 60 side wall, 65 bottom plate, 65a bottom surface of bottom plate.

Claims

1. A bottom plate that supports multiple batteries; a side wall extending in a thickness direction of the bottom plate from an outer edge of an upper surface of the bottom plate so as to surround a mounting surface of the upper surface for the plurality of batteries, and defining, together with the bottom plate, a battery accommodating space for accommodating the plurality of batteries; a plate-shaped permanent magnet fixed to at least a portion of the bottom surface of the bottom plate; Equipped with a plurality of storage sections each for storing a battery and spaced apart from one another are provided in the battery storage space; The permanent magnet has a storage overlap portion that overlaps at least a portion of each of the storage portions when viewed in the thickness direction.

2. The battery housing tray according to claim 1 , further comprising an insulating resin that covers at least a portion of the bottom surface of the permanent magnet.

3. the permanent magnet is fixed to an area of ​​the bottom surface that includes all of the portions that overlap with the plurality of housing portions in the thickness direction, The battery housing tray according to claim 1 or 2, further comprising an insulating resin that covers the entire bottom surface of the permanent magnet.

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