Fire spread prevention sheet and battery including same

Abstract

To provide a fire spread prevention sheet capable of changing a thickness according to a volume change in a battery cell, and a battery including the same.SOLUTION: This pneumatic tire is formed by laminating three kinds of rubber molded bodies different in rubber hardness so that the rubber hardness becomes higher in order from one direction, and a first rubber molded body 11 having the lowest hardness has a first projecting part side 31a on at least one surface. The third rubber molded body 13 having the highest hardness has, on at least one surface thereof, a third concave 31a into which the first convex 33b can be inserted, and the second rubber molded body 12 having the medium hardness is a flat molded body that is sandwiched between the surface of the first rubber molded body 11 on the side of the first convex 31a and the surface of the third rubber molded body 13 on the side of the third concave 33b to close the third concave 33b. The present invention relates to a fire spread prevention sheet 1 whose thickness can be reduced by compression from a thickness direction of the fire spread prevention sheet 1 causing a first protrusion side 31a to enter a third recess side 33b together with a part of a second rubber molded body 12, and a battery including the fire spread prevention sheet 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire prevention sheet and a battery equipped with the same. [Background technology]

[0002] Currently, there is a growing movement around the world to gradually replace conventional gasoline or diesel vehicles with electric vehicles in order to reduce the burden on the global environment. Electric vehicles are becoming increasingly popular, particularly in European countries such as France, the Netherlands, and Germany, as well as in China. The widespread use of electric vehicles requires high-performance batteries.

[0003] In recent years, automobile batteries have become known that have multiple battery cells arranged inside a housing, and these batteries use sheets (hereinafter simply referred to as "sheets") to separate the battery cells. In such a battery in which multiple battery cells are installed side by side, a fire that occurs in one battery cell can spread to adjacent battery cells, causing problems such as larger fires, smoke, and explosions. To prevent this, it is necessary to make it difficult for the heat from an abnormally hot battery cell to be transferred to surrounding battery cells. To address this, for example, a method is known in which a fire-prevention sheet such as a fire-resistant material or a heat-insulating layer is provided between multiple battery cells (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-206604 Summary of the Invention [Problem to be solved by the invention]

[0005] After being installed in a housing, battery cells contract and expand due to internal temperature changes during battery discharge and charging. Conventional fire prevention sheets placed between battery cells tend to increase internal stress as the sheet's thickness decreases when compressed under pressure from the battery cells. This prevents sufficient contraction and deformation in the sheet's thickness direction, resulting in problems such as impeded expansion of the battery cells and excessive internal pressure within the battery cells. Solving this issue will also contribute to achieving the applicant's Sustainable Development Goal of "ensuring access to affordable, reliable, sustainable, and modern energy for all."

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a fire prevention sheet that increases internal stress at the beginning of shrinkage in the thickness direction of the sheet, but then deforms so that the increase in internal stress becomes extremely small, allowing the expansion of the battery cell and preventing excessive pressure increase inside the cell, and a battery equipped with the same. [Means for solving the problem]

[0007] (1) To achieve the above object, a fire prevention sheet according to one embodiment is a fire prevention sheet that is disposed at least between a plurality of battery cells and can prevent the spread of fire between the battery cells, Three types of rubber moldings with different rubber hardness are layered in order of increasing rubber hardness from one direction. The first rubber molding, which has the lowest hardness among the three types of rubber moldings, has one or more first convex portions on at least one surface thereof, a third rubber molding having the highest hardness among the three types of rubber moldings, which has one or more third recesses on at least one surface into which the first protrusions can be inserted, Among the three types of rubber moldings, a second rubber molding having a medium hardness is a flat-plate-shaped molding that is sandwiched between a surface of the first rubber molding on the side of the first convex portion and a surface of the third rubber molding on the side of the third concave portion and closes the third concave portion, When the fire spread prevention sheet is compressed in the thickness direction, the first convex portion enters the third concave portion together with a part of the second rubber molding, thereby reducing the thickness. (2) In another embodiment of the fire spread prevention sheet, preferably, the first convex portions have an elongated shape and are formed in a plurality of rows within a plane in the thickness direction of the first rubber molding, The third recesses may be elongated and formed in a plurality of rows within a plane in the thickness direction of the third rubber molding. (3) To achieve the above object, a fire prevention sheet according to one embodiment is a fire prevention sheet that is disposed at least between a plurality of battery cells and can prevent the spread of fire between the battery cells, Three types of rubber moldings with different rubber hardness are layered in order of increasing rubber hardness from one direction. The first rubber molding, which has the lowest hardness among the three types of rubber moldings, has one or more first recesses on at least one surface thereof, a third rubber molding having the highest hardness among the three types of rubber moldings has one or more third protrusions on at least one surface thereof that can be inserted into the first recess; Among the three types of rubber moldings, a second rubber molding having a medium hardness is a flat-plate-shaped molding that is sandwiched between a surface of the first rubber molding on the first recess side and a surface of the third convex portion of the third rubber molding and closes the first recess, When the fire spread prevention sheet is compressed in the thickness direction, the third convex portion enters the first concave portion together with a part of the second rubber molding, thereby reducing the thickness. (4) In another embodiment of the fire spread prevention sheet, the first recesses are preferably elongated and formed in a plurality of rows within a plane in the thickness direction of the first rubber molding, The third protrusions may be elongated and formed in a plurality of rows within a plane in the thickness direction of the third rubber molding. (5) In another embodiment of the fire spread prevention sheet, preferably, the first rubber molding has a first recess between adjacent first protrusions, the third rubber molding has a third protrusion between adjacent third recesses, The first rubber molding and the third rubber molding may sandwich the second molding, with the first convex portion facing the third concave portion and the first concave portion facing the third convex portion. (6) In another embodiment of the fire spread prevention sheet, preferably, the first convex portions and the first concave portions have an elongated shape and are formed in a plurality of rows within a plane in the thickness direction of the first rubber molding, The third convex portions and the third concave portions may be elongated and formed in a plurality of rows within a plane in the thickness direction of the third rubber molding. (7) In another embodiment of the fire spread prevention sheet, the inner diameter of the third recess is preferably at least twice the outer diameter of the first protrusion, The inner diameter of the first recess may be at least twice the outer diameter of the third protrusion. (8) In another embodiment of the fire spread prevention sheet, preferably, the width of the third recess is at least twice the width of the first protrusion, The width of the first recess may be at least twice as large as the width of the third protrusion. (9) In the fire spread prevention sheet according to another embodiment, preferably, the thickness of the second rubber molding may be smaller than the thicknesses of the first rubber molding and the third rubber molding. (10) In the fire spread prevention sheet according to another embodiment, preferably, at least one of the first rubber molding, the second rubber molding, and the third rubber molding may contain silicone rubber. (11) In order to achieve the above object, a battery according to one embodiment includes a plurality of battery cells in a housing, Any one of the fire spread prevention sheets described above is provided at least between the battery cells, among between the battery cells and between the battery cells and the housing. [Effects of the Invention]

[0008] According to the present invention, internal stress increases at the beginning of the sheet's shrinkage in the thickness direction, but the sheet subsequently deforms so that the increase in internal stress becomes extremely small, allowing the battery cell to expand and preventing excessive pressure increase inside the cell. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 shows an exploded perspective view (1A) of a fire spread prevention sheet according to one embodiment before assembly and a perspective view (1B) of the sheet after assembly. [Figure 2] FIG. 2 shows a plan view, a front view, a side view of the assembled fire spread prevention sheet of FIG. 1, and an enlarged view of part A of the front view. [Figure 3] FIG. 3 shows a cross-sectional view of the fire spread prevention sheet of FIG. 1 when it is compressed in the thickness direction (changes in the order 3A, 3B, 3C with increasing pressure). [Figure 4] FIG. 4 shows a cross-sectional view of the change (changes in the order 4A, 4B, and 4C with increasing pressure) when a single flat sheet molding is compressed in the thickness direction as a comparative material. [Figure 5] FIG. 5 shows a cross-sectional view of the changes that occur when a laminate serving as a comparative material having a different form from the fire spread prevention sheet of FIG. 1 is compressed in the thickness direction (changes in the order 5A, 5B, and 5C as pressure is applied). [Figure 6] FIG. 6 shows the relationship between strain and stress caused by compression of the various compression objects shown in FIG. [Figure 7] FIG. 7 shows a longitudinal cross-sectional view of a battery according to one embodiment and an enlarged view of one fire spread prevention sheet sandwiched between battery cells in the longitudinal cross-sectional view. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below do not limit the invention according to the claims, and not all of the elements and combinations thereof described in the embodiments are necessarily essential to the solution of the present invention.

[0011] 1. Fire prevention sheet (1) Composition of the fire prevention sheet The fire spread prevention sheet 1 according to the embodiment is a sheet that is disposed at least between a plurality of battery cells and can prevent the spread of fire between the battery cells. Here, the "battery cell" refers, for example, to a battery cell (also simply referred to as a "cell") disposed inside an automobile battery, but it may also refer to a battery cell used for purposes other than automobiles. In addition to being used in contact with a battery cell, the fire spread prevention sheet 1 may also be used in contact with, for example, a heater or its components, or components within an electrical or electronic device (such as a circuit board or circuit parts).

[0012] FIG. 1 shows an exploded perspective view (1A) of a fire spread prevention sheet according to one embodiment before assembly and a perspective view (1B) of the sheet after assembly.

[0013] The fire spread prevention sheet 1 is composed of three types of rubber molded bodies with different rubber hardness: a first rubber molded body 11, a second rubber molded body 12, and a third rubber molded body 13, stacked in order of increasing rubber hardness from one direction. The first rubber molded body 11, which has the lowest hardness among the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13, has one or more first convex portions 31a on at least one of both surfaces in the thickness direction. The third rubber molded body 13, which has the highest hardness among the three types of rubber molded bodies, has one or more third concave portions 33b into which the first convex portions 31a can be inserted on at least one of both surfaces in the thickness direction. The second rubber molded body 12, which has a medium hardness among the three types of rubber molded bodies, is a flat-plate molded body that is sandwiched between the surface of the first convex portion 31a of the first rubber molded body 11 and the surface of the third concave portion 33b of the third rubber molded body 13, thereby closing the third concave portion 33b. The fire spread prevention sheet 1 is a laminated body that can reduce its thickness by being compressed in its thickness direction, with the first convex portions 31a entering the third concave portions 33b together with parts of the second rubber moldings 12. In this embodiment, the first rubber moldings 11 have first concave portions 31b between adjacent first convex portions 31a. The third rubber moldings 13 have third convex portions 33a between adjacent third concave portions 33b. The first rubber moldings 11 and the third rubber moldings 13 sandwich the second moldings 12, with the first convex portions 31a facing the third concave portions 33b and the first concave portions 31b facing the third convex portions 33a.

[0014] In this embodiment, the first convex portions 31a and the first concave portions 31b preferably have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the first rubber molding body 11. The third convex portions 33a and the third concave portions 33b also have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the third rubber molding body 13.

[0015] Examples of rubber that can be used for the fire spread prevention sheet 1 include thermosetting elastomers such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, nitrile rubber (NBR), and styrene butadiene rubber (SBR); thermoplastic elastomers such as urethane-based, ester-based, styrene-based, olefin-based, butadiene-based, and fluorine-based elastomers, and composites thereof. Among these rubbers, silicone rubber, which has relatively high heat resistance, is preferred. Furthermore, the rubber is preferably porous rubber, such as foamed rubber. Porous rubber contains numerous air bubbles within it. The air within the bubbles exhibits lower thermal conductivity than the rubber matrix. Therefore, by including porous rubber in at least one of the first rubber molding body 11, the second rubber molding body 12, and the third rubber molding body 13, the heat insulation properties of the fire spread prevention sheet 1 can be further improved.

[0016] Furthermore, at least one of the first rubber molding 11, the second rubber molding 12, and the third rubber molding 13 of the fire spread prevention sheet 1 may preferably contain a filler. Examples of the filler include fillers made of one or more of perlite, alumina borosilicate glass, soda-lime borosilicate glass, mica, and glass fiber.

[0017] The rubber hardness of the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13 increases in this order. All of the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13 may be solid rubber molded bodies, or some of these molded bodies may be solid rubber molded bodies and the other molded bodies excluding these may be porous rubber molded bodies, or all of these rubber molded bodies may be porous rubber molded bodies. When all of the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13 are solid rubber molded bodies, the rubber hardness measured using, for example, a Type A durometer conforming to JIS K 6253 increases in the order of the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13. When the first rubber molding 11, the second rubber molding 12, and the third rubber molding 13 are all porous rubber moldings, the rubber hardness measured using, for example, a Type E durometer conforming to JIS K 6253 or an Asker C (spring-type Asker C) conforming to SRIS 0101 increases in the order of the first rubber molding 11, the second rubber molding 12, and the third rubber molding 13. On the other hand, when some of the moldings are solid rubber moldings and the remaining moldings are porous rubber moldings, the measurement methods for each hardness are different, but a Type A durometer or a Type E durometer (or a spring-type Asker C may alternatively be used) can be used depending on the hardness. The thickness of the compressed fire-preventing sheet 1 can be reduced depending on the depth of the first recess 31b into which the second rubber molding 12 fits and / or the third recess 33b of the third rubber molding 13. How the first rubber molding 11, the second rubber molding 12 and the third rubber molding 13 deform when the fire spread prevention sheet 1 is compressed will be described in more detail below.

[0018] FIG. 2 shows a plan view, a front view, a side view of the assembled fire spread prevention sheet of FIG. 1, and an enlarged view of part A of the front view.

[0019] In this embodiment, the thickness of the second rubber molding 12 is preferably smaller than the thickness of each of the first rubber molding 11 and the third rubber molding 13. This is because, when the fire spread prevention sheet 1 is compressed in its thickness direction, a portion of the second rubber molding 12 that is pressed from the first rubber molding 11 side and / or the third rubber molding 13 side is likely to deform in a direction that enters the recess of the first rubber molding 11 side and / or the third rubber molding 13.

[0020] The width (d4) of the third recess 33b in the fire spread prevention sheet 1 is preferably at least twice the width (d1) of the first protrusion 31a. Furthermore, the width (d3) of the first recess 31b is preferably at least twice the width (d2) of the third protrusion 33a. Designing each width to these values ​​makes it easier for the first protrusion 31a to move over the second rubber molding 12 and be inserted into the third recess 33b, and for the first protrusion 31a itself to bend and deform. This bending of the first protrusion 31a itself also contributes to a significant reduction in the thickness of the fire spread prevention sheet 1 when compressed.

[0021] Furthermore, the first convex portions 31a, the first concave portions 31b, the third convex portions 33a, and the third concave portions 33b may be dot-shaped within the planes of the first rubber molding 11 and the third rubber molding 13 in the thickness direction. In this case, it is preferable to set the sizes of the first convex portions 31a, the first concave portions 31b, the third convex portions 33a, and the third concave portions 33b as follows: The inner diameter (d4) of the third concave portion 33b is preferably at least twice the outer diameter (d1) of the first convex portion 31a. The inner diameter (d3) of the first concave portion 31b is preferably at least twice the outer diameter (d2) of the third convex portion 33a. Even with these diameters, the first convex portions 31a can easily move over the second rubber molding 12 and be inserted into the third concave portion 33b, and the first convex portions 31a themselves can easily bend and deform.

[0022] Next, we will explain the results of a computer simulation of the morphological changes that occur when various fire prevention sheets are compressed in the thickness direction. For the computer simulation, we used Marc nonlinear finite element analysis software from MSC Software Co., Ltd.

[0023] Figure 3 shows a cross-sectional view of the fire spread prevention sheet of Figure 1 when it is compressed in its thickness direction (changing from 3A to 3B to 3C as pressure is applied). Figure 4 shows a cross-sectional view of the change when a single flat sheet molding as a comparative material is compressed in its thickness direction (changing from 4A to 4B to 4C as pressure is applied). Figure 5 shows a cross-sectional view of the change when a laminate as a comparative material having a different form from the fire spread prevention sheet of Figure 1 is compressed in its thickness direction (changing from 5A to 5B to 5C as pressure is applied). In Figures 3, 4, and 5, the downward arrow drawn above the compressed object indicates the direction of pressure application. The conditions entered for the analysis using the above software are as follows: Each sheet size (common): length 100mm, width 50mm, thickness 10mm Density (common): 0.36g / cm 3 Poisson's ratio (common): 0.49 Elasticity: First rubber molding (low hardness molding): 2 MPa Second rubber molding (medium hardness molding): 5 MPa Third rubber molding (high hardness molding): 8 MPa

[0024] As shown in Figure 3, when the fire spread prevention sheet 1 is compressed in its thickness direction, it expands in a direction parallel to the thickness direction and reduces in thickness. As the thickness reduces, the second rubber molding 12 deforms in a wavy shape. Furthermore, the first convex portion 31a moves in a direction to enter the third recessed portion 33b together with a part of the second rubber molding 12. However, due to the resistance of the second rubber molding 12, the first convex portion 31a and the third convex portion 33a cannot be completely inserted into the third recessed portion 33b and the first recessed portion 31b, and are instead deformed in a bending manner.

[0025] On the other hand, when a single flat sheet molding 2 is compressed in its thickness direction, it expands in a direction parallel to the plane in the thickness direction and reduces in thickness, as shown in Figure 4. Since the single flat sheet molding 2 has a simpler structure than the fire spread prevention sheet 1, the change in shape in response to compression in the thickness direction is extremely simple.

[0026] Similar to the fire spread prevention sheet 1, the laminate 3 in FIG. 5 is made up of three types of rubber molded bodies with different rubber hardnesses, specifically, a first rubber molded body 11, a second rubber molded body 12, and a third rubber molded body 13, stacked in order of increasing rubber hardness. The first rubber molded body 11, which has the lowest hardness among the first rubber molded body 11, the second rubber molded body 12, and the third rubber molded body 13, has multiple first protrusions 31a on one side and multiple first recesses 31b into which the second protrusions 32a of the second rubber molded body 12 can be inserted. The third rubber molded body 13, which has the highest hardness among the three types of rubber molded bodies 11, 12, and 13, is a flat-plate-shaped molded body. The second rubber molded body 12, which has a medium hardness, has multiple second recesses 32b on one side into which the first protrusions 31a can be inserted, and multiple second protrusions 32a. The second rubber molding 12 is sandwiched between the surface of the first rubber molding 11 facing the first convex portion 31 a and the first concave portion 31 b and one surface of the third rubber molding 13 .

[0027] As shown in FIG. 5, when the laminate 3 is compressed in its thickness direction, it expands in a direction parallel to the plane in the thickness direction and reduces in thickness. However, unlike the fire spread prevention sheet 1, the laminate 5 does not have any inclusions that would provide resistance between the first convex portions 31a and the second concave portions 32b, or between the second convex portions 32a and the first concave portions 31b, when compressed in the thickness direction. Therefore, the first convex portions 31a immediately enter the second concave portions 32b. Similarly, the second convex portions 32a immediately enter the first concave portions 31b. The laminate 3 is compressed with its concave and convex portions interlocking with each other, reducing its thickness.

[0028] Figure 6 shows the relationship between strain and stress due to compression of the various compressed objects in Figure 5. Here, strain refers to the percentage (%) of thickness reduction from the thickness before compression, and stress refers to the force (MPa) exerted by the compressed object in the direction opposite to the compression direction.

[0029] The stress of the fire spread prevention sheet 1 increases with increasing strain in the initial stage of compression, maintaining a constant value of approximately 1 MPa until the strain reaches approximately 25% after reaching approximately 10%. Once the strain exceeds approximately 25%, the stress of the fire spread prevention sheet 1 increases again (see solid curve a). Thus, even when the fire spread prevention sheet 1 is compressed in its thickness direction, a region (hereinafter also referred to as the "flat region") is created where the internal stress does not increase significantly as the thickness of the sheet decreases (increasing strain) and remains approximately constant. When the fire spread prevention sheet 1 is sandwiched between battery cells, the sheet 1 exerts stress on the battery cells in proportion to the decrease in thickness during the initial stage of installation inside the battery casing. Subsequently, when the internal pressure of the battery cells increases during charging or discharging of the battery and the fire spread prevention sheet 1 is further compressed, the fire spread prevention sheet 1 reduces its thickness without significant resistance. This prevents the battery cells from expanding and reduces the internal pressure of the battery cells from becoming too high.

[0030] On the other hand, the stress of the single flat sheet molding 2 increases as the strain increases (see dashed curve b). The stress-strain curve of the single flat sheet molding 2 does not have a flat region like that seen in the fire spread prevention sheet 1. Next, the stress of the laminate 3 increases slowly until the initial strain of compression reaches 10%. However, thereafter, the stress increases rapidly with the strain (see dotted curve c). Thus, like the single flat sheet molding 2, the stress-strain curve of the laminate 3 does not have a flat region like that seen in the fire spread prevention sheet 1.

[0031] The range of the flat area and stress value of the fire spread prevention sheet 1 can be adjusted by the hardness and thickness of the first rubber molding 11, the second rubber molding 12, and the third rubber molding 13, and the arrangement, size, number, and shape of the first convex portion 31a, the first concave portion 31b, the third convex portion 33a, and the third concave portion 33b.

[0032] 2. Battery FIG. 7 shows a longitudinal cross-sectional view of a battery according to one embodiment and an enlarged view of one fire spread prevention sheet sandwiched between battery cells in the longitudinal cross-sectional view.

[0033] The battery 40 according to this embodiment is, for example, a battery for an electric vehicle, and includes a plurality of battery cells (also simply referred to as "cells") 41 arranged side by side. In this embodiment, the number of battery cells 41 is eight, but may be two to seven, or nine or more. The battery 40 is a storage battery, preferably a lithium-ion battery. The battery 40 includes a housing 42 with a bottom that is open on one side. The battery cells 41 are disposed inside 43 of the housing 42. The plurality of battery cells 41 are preferably pressed against each other by applying compressive force from both sides of the housing 42 using screws or the like (not shown). The bottom of the housing 42 is provided with a through-hole 44 for allowing cooling water, which is an example of a coolant, to flow through. The coolant may also be referred to as a cooling medium or a coolant. The battery cells 41 are disposed inside the housing 42 with a fire-prevention sheet 1 sandwiched between adjacent battery cells 41.

[0034] As described above, the battery 40 according to the present invention includes a plurality of battery cells 41 in a housing 42, and includes the fire prevention sheet 1 at least between the battery cells 41, either between the battery cells 41 or between the battery cells 41 and the housing 42. The fire prevention sheet 1 does not have to be disposed between the battery cells 41 and the housing 42.

[0035] The fire spread prevention sheet 1 arranged between the battery cells 41 is a sheet in which three types of rubber molded bodies with different rubber hardness, namely a first rubber molded body 11, a second rubber molded body 12, and a third rubber molded body 13, are laminated in order of increasing rubber hardness from one side to the other. When the battery cells 41 are set in the housing 42, the fire spread prevention sheet 1 is sandwiched at least between the battery cells 41.

[0036] 3. Other embodiments Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be practiced in various modified forms.

[0037] The first convex portions 31a and the first concave portions 31b in the above-described fire spread prevention sheet 1 are not limited to elongated shapes that are long in one direction within the plane of the thickness direction of the first rubber molding 11, but may also be formed in a dot shape that is long in the thickness direction of the first rubber molding 11. Similarly, the third convex portions 33a and the third concave portions 33b are not limited to elongated shapes that are long in one direction within the plane of the thickness direction of the third rubber molding 13, but may also be formed in a dot shape that is long in the thickness direction of the third rubber molding 13 within the plane.

[0038] Instead of the above-described configuration, the fire spread prevention sheet 1 may have a configuration with the following first modification. For example, the first rubber molding 11 may have only one or two or more first recesses 31b on at least one side, and may not have any first protrusions 31a. In this case, the third rubber molding 13 may have only one or two or more third protrusions 33a that can be inserted into the first recesses 31b on at least one side, and may not have any third recesses 33b. The second rubber molding 12 may be a flat-plate-shaped molding that is sandwiched between the surface of the first rubber molding 11 facing the first recess 31b and the surface of the third protrusion 33a of the third rubber molding 13, thereby closing the first recess 31b. The fire spread prevention sheet 1 configured in this manner is a laminate that can be compressed in its thickness direction, causing the third protrusions 33a to enter the first recesses 31b together with part of the second rubber molding 12, thereby reducing its thickness.

[0039] In the embodiment in which the first modification is applied, the first recesses 31b preferably have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the first rubber molding body 11. The third protrusions 33a also have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the third rubber molding body 13. The first recesses 31b are not limited to an elongated shape that is long in one direction within the plane in the thickness direction of the first rubber molding body 11, but may be formed in a dot shape that is long in the thickness direction of the first rubber molding body 11 within the plane. Similarly, the third protrusions 33a are not limited to an elongated shape that is long in one direction within the plane in the thickness direction of the third rubber molding body 13, but may be formed in a dot shape that is long in the thickness direction of the third rubber molding body 13 within the plane.

[0040] As another embodiment, the fire spread prevention sheet 1 may have a second modified form as follows. For example, the first rubber molding 11 may have only one or two or more first convex portions 31a on at least one side, and no first concave portions 31b. In this case, the third rubber molding 13 may have only one or two or more third concave portions 33b on at least one side into which the first convex portions 31a can be inserted, and may not have any third convex portions 33a. The second rubber molding 12 may be a flat-plate-shaped molding sandwiched between the surface of the first rubber molding 11 facing the first convex portion 31a and the surface of the third rubber molding 13 facing the third concave portion 33b, thereby closing the third concave portion 33b. The fire spread prevention sheet 1 configured in this manner is a laminate that can be compressed in its thickness direction, causing the first convex portions 31a to enter the third concave portion 33b together with a part of the second rubber molding 12, thereby reducing its thickness.

[0041] In the embodiment in which the second modification is applied, the first convex portions 31a preferably have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the first rubber molding body 11. The third concave portions 33b also have an elongated shape and are formed in multiple rows within the plane in the thickness direction of the third rubber molding body 13. The first convex portions 31b are not limited to an elongated shape that is long in one direction within the plane in the thickness direction of the first rubber molding body 11, but may be formed in a dot shape that is long in the thickness direction of the first rubber molding body 11 within the plane. Similarly, the third concave portions 33b are not limited to an elongated shape that is long in one direction within the plane in the thickness direction of the third rubber molding body 13, but may be formed in a dot shape that is long in the thickness direction of the third rubber molding body 13 within the plane.

[0042] The features of the claims may be combined in any combination except where they are incombinable with one another. [Industrial Applicability]

[0043] The present invention can be used to prevent the spread of fire by sandwiching at least heat sources between them. [Explanation of symbols]

[0044] 1...fire prevention sheet, 11...first rubber molding (a type of rubber molding), 12...second rubber molding (a type of rubber molding), 13...third rubber molding (a type of rubber molding), 31a...first convex portion, 31b...first concave portion, 33a...third convex portion, 33b...third concave portion, 40...battery, 41...battery cell (an example of a heat source), 42...casing.

Claims

1. A fire prevention sheet that is disposed at least between a plurality of battery cells and can prevent the spread of fire between the battery cells, Three types of rubber moldings with different rubber hardness are layered in order of increasing rubber hardness from one direction. The first rubber molding having the lowest hardness among the three types of rubber moldings has one or more first convex portions on at least one surface thereof, a third rubber molding having the highest hardness among the three types of rubber moldings, the third rubber molding having one or more third recesses on at least one surface thereof into which the first protrusions can be inserted, Among the three types of rubber moldings, a second rubber molding having a medium hardness is a flat-plate-shaped molding that is sandwiched between a surface of the first rubber molding on the first convex portion side and a surface of the third rubber molding on the third concave portion side and closes the third concave portion, A fire spread prevention sheet in which, when compressed in the thickness direction of the fire spread prevention sheet, the first convex portion enters the third concave portion together with a part of the second rubber molding, thereby reducing the thickness.

2. the first protrusions have an elongated shape and are formed in a plurality of rows within a plane in a thickness direction of the first rubber molding body, The fire spread prevention sheet according to claim 1, characterized in that the third recesses are elongated and formed in multiple rows within the thickness direction of the third rubber molding.

3. A fire prevention sheet that is disposed at least between a plurality of battery cells and can prevent the spread of fire between the battery cells, Three types of rubber moldings with different rubber hardness are layered in order of increasing rubber hardness from one direction. a first rubber molding having the lowest hardness among the three types of rubber moldings, the first rubber molding having one or more first recesses on at least one surface thereof; a third rubber molding having the highest hardness among the three types of rubber moldings, the third rubber molding having one or more third protrusions on at least one surface thereof that can be inserted into the first recess; Among the three types of rubber moldings, a second rubber molding having a medium hardness is a flat-plate-shaped molding that is sandwiched between a surface of the first rubber molding on the first recess side and a surface of the third convex portion of the third rubber molding and closes the first recess, A fire spread prevention sheet in which the thickness can be reduced by compressing the fire spread prevention sheet in the thickness direction, causing the third convex portion to enter the first concave portion together with a part of the second rubber molding.

4. the first recesses have an elongated shape and are formed in a plurality of rows within a plane in a thickness direction of the first rubber molding body, The fire spread prevention sheet according to claim 3, characterized in that the third convex portion is elongated and formed in multiple rows within the thickness direction of the third rubber molding.

5. the first rubber molding has a first recess between adjacent first protrusions, the third rubber molding has a third convex portion between adjacent third concave portions, The fire spread prevention sheet described in claim 1, characterized in that the first rubber molding and the third rubber molding sandwich the second molding, with the first convex portion facing the third concave portion and the first concave portion facing the third convex portion.

6. the first convex portion and the first concave portion have an elongated shape and are formed in a plurality of rows within a plane in a thickness direction of the first rubber molding body, The fire spread prevention sheet described in claim 5, characterized in that the third convex portion and the third concave portion are elongated and formed in multiple rows within the thickness direction of the third rubber molding.

7. an inner diameter of the third recess is at least twice the outer diameter of the first protrusion; 6. The fire spread prevention sheet according to claim 5, wherein the inner diameter of the first recess is at least twice the outer diameter of the third protrusion.

8. the width of the third recess is at least twice the width of the first protrusion, 7. The fire spread prevention sheet according to claim 6, wherein the width of the first recess is at least twice the width of the third protrusion.

9. 2. The fire spread prevention sheet according to claim 1, wherein the thickness of the second rubber molding is smaller than the thicknesses of the first rubber molding and the third rubber molding.

10. 10. The fire spread prevention sheet according to claim 9, wherein at least one of the first rubber molding, the second rubber molding, and the third rubber molding contains silicone rubber.

11. A battery having a plurality of battery cells in a housing, A battery comprising the fire spread prevention sheet according to any one of claims 1 to 10, at least between the battery cells, among between the battery cells and between the battery cells and the housing.

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