Fire spread prevention sheet, method of manufacturing same, and battery including same

Abstract

[Problem] To provide: a fire spread prevention sheet having high heat-insulating and heat-resistant properties and capable of reducing drop-off of part of constituents of a heat-insulating material; a method of manufacturing the same; and a battery including the same.　[Solution] The present invention relates to: a fire spread prevention sheet 1a placed at least between a plurality of heat sources, and capable of preventing fire spread by suppressing heat transfer to other heat sources when a heat source is in an overheated state, the fire spread prevention sheet 1a having a structure in which a resin sheet 2 and a heat insulation sheet 3 having a lower thermal conductivity than the resin sheet 2 are laminated, the resin sheet 2 having a hole 2b penetrating in the thickness direction and / or a recess 2a recessed inward from the outer surface of the sheet 2; a method of manufacturing the fire spread prevention sheet 1a; and a battery including the sheet 1a.

Description

Fire prevention sheet, its manufacturing method and battery equipped with same Cross Reference

[0001] This application claims priority under the Paris Agreement based on Japanese Patent Application No. 2024-066084, filed in Japan on April 16, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a fire prevention sheet, a method for manufacturing the same, and a battery including the same.

[0003] 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.

[0004] Some batteries may experience thermal runaway during discharge or charging, resulting in fire, smoke, or other problems. Recently, automotive batteries have become known that have multiple battery cells arranged in a housing. In such a battery with multiple battery cells arranged in a row, if one battery cell ignites or emits smoke, the heat may be transferred to the surrounding battery cells, potentially causing further fires, smoke, explosions, or other problems. To minimize damage caused by such problems, methods have been developed to prevent the transfer of heat from abnormally high-temperature battery cells to the surrounding battery cells. 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).

[0005] Japanese Patent Application Laid-Open No. 2018-206604

[0006] However, conventional methods do not necessarily provide sufficient insulation and heat resistance (fire resistance) for fire prevention sheets. To solve this problem, the present inventors, prior to the present invention, considered using a heat insulating sheet with excellent heat insulation properties containing a metal oxide such as silica. They discovered that when such a heat insulating sheet is used, the metal oxide is prone to falling off the heat insulating sheet. Based on this experience, the present inventors recognized that it is necessary not only to improve the heat insulating properties and heat resistance, but also to reduce the risk of some of the materials constituting the heat insulating sheet falling off and scattering into the surrounding area. Furthermore, solving this problem will also contribute to the achievement of the applicant's Sustainable Development Goal of "ensuring access to affordable, reliable, sustainable, and modern energy for all."

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a fire spread prevention sheet that has high insulation and heat resistance and can reduce the loss of some of the components of the insulation material, a method for manufacturing the same, and a battery equipped with the same.

[0008] (1) To achieve the above object, one embodiment of a fire spread prevention sheet is disposed at least between multiple heat sources and is capable of preventing the spread of fire by suppressing heat transfer to other heat sources when one of the heat sources is overheated. The fire spread prevention sheet has a laminated structure comprising: a resin sheet; and an insulating sheet having a lower thermal conductivity than the resin sheet. The resin sheet has a hole penetrating through the resin sheet in its thickness direction and / or a recess recessed inward from the outer surface of the resin sheet. (2) Another embodiment of a fire spread prevention sheet may preferably include the resin sheet on both sides of the insulating sheet in the thickness direction. (3) Another embodiment of a fire spread prevention sheet may preferably include the resin sheet being a sheet of polypropylene, polyvinyl chloride, polyethylene terephthalate, or polycarbonate. (4) Another embodiment of a fire spread prevention sheet may preferably include the insulating sheet being a sheet containing talc, diatomaceous earth, silica, silica aerogel, or mica. (5) A method for manufacturing a fire spread prevention sheet according to one embodiment for achieving the above object includes the steps of: forming the holes and / or the recesses in the resin sheet; and attaching the resin sheet with the holes and / or the recesses formed therein and the insulating sheet in a stacked state. (6) A method for manufacturing a fire spread prevention sheet according to another embodiment preferably includes the steps of: overlapping the insulating sheet with the resin sheet or a curable resin sheet that will harden to form the resin sheet; and pressing a plate having projections and recesses from the side of the resin sheet or the curable resin sheet to attach the resin sheet and the insulating sheet and form the holes and / or the recesses in the resin sheet. (7) A battery according to one embodiment for achieving the above object includes a battery having a housing containing a plurality of battery cells, and comprising any one of the fire spread prevention sheets described above between the battery cells and between the battery cells and the housing, at least between the battery cells.

[0009] According to the present invention, it is possible to provide a fire spread prevention sheet that has high thermal insulation and heat resistance and is capable of reducing the loss of some of the constituent components of the thermal insulation material, a method for manufacturing the same, and a battery including the same.

[0010] FIG. 1 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a first embodiment. FIG. 2 shows A-A cross-sectional views (2A, 2B, 2C) of various variations of the resin sheet constituting the fire spread prevention sheet of FIG. 1. FIG. 3 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a second embodiment. FIG. 4 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a third embodiment. FIG. 5 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a fourth embodiment. FIG. 6 is a longitudinal cross-sectional view (6A, 6B) showing a process of manufacturing a fire spread prevention sheet by pressing a plate against the plane of the resin sheet. FIG. 7 is a longitudinal cross-sectional view showing a process of manufacturing a resin sheet by pressing plates against the plane and bottom of the resin sheet. FIG. 8 is a longitudinal cross-sectional view showing a process of pressure-bonding a resin sheet to a heat insulating sheet in a process of manufacturing a fire spread prevention sheet according to the first embodiment. FIG. 9 is a longitudinal cross-sectional view showing a process of manufacturing a fire spread prevention sheet according to a second embodiment. FIG. 10 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.

[0011] 1, 1a, 1b, 1c, 1d...fire prevention sheet, 2...resin sheet, 2'...curable resin sheet, 2a...recess, 2b...hole, 3...insulating sheet, 5...plate, 5a...protrusion, 10...battery, 11...casing, 20...battery cell (an example of a heat source).

[0012] Next, various embodiments of the present invention will be described with reference to the drawings. Note that the various embodiments described below do not limit the scope of the invention as claimed, and not all of the elements and combinations thereof described in the various embodiments are necessarily essential to the solution of the present invention.

[0013] 1. Fire Spread Prevention Sheet First Embodiment (1) Configuration of Fire Spread Prevention Sheet Fig. 1 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a first embodiment.

[0014] The fire spread prevention sheet 1a is a sheet that is placed at least between multiple heat sources and can prevent the spread of fire while suppressing heat transfer to other heat sources when a heat source is overheated. Here, examples of "heat sources" include battery cells (also simply referred to as "cells") placed inside an automobile battery, batteries used in devices other than automobiles, or battery cells placed inside such batteries. However, "heat sources" also include, in addition to battery cells, heaters or their components, and components in electrical or electronic devices (circuit boards, circuit parts, etc.).

[0015] As shown in FIG. 1 , the fire spread prevention sheet 1a according to the first embodiment has a laminated structure of a resin sheet 2 and a heat insulating sheet 3. The resin sheet 2 is pressure-bonded to one surface of the heat insulating sheet 3, thereby preventing materials (e.g., particles of metal oxides) constituting the heat insulating sheet 3 from scattering from the surface of the heat insulating sheet 3 into the interior of a device equipped with the fire spread prevention sheet 1a, such as a battery or electronic device. When the fire spread prevention sheet 1a is used for a battery cell, which is an example of a heat source, the resin sheet 2 may be positioned so that it contacts either the battery cell or the housing. The resin sheet 2 is positioned between the heat insulating sheet 3 and the battery cell. Here, the resin sheet 2 has a plurality of recesses 2a recessed inward from the outer surface of the sheet or holes 2b penetrating through the thickness direction. The recesses 2a or holes 2b contain air, which has a lower thermal conductivity than the resin, thereby suppressing heat conduction between the battery cells.

[0016] (2) Resin Sheet The resin sheet 2 has a plurality of recesses 2a and / or holes 2b recessed inward from the outer surface of the sheet. Here, "holes" refers to through holes that penetrate the resin sheet 2 in the thickness direction. The recesses 2a or holes 2b contain air, which has a lower thermal conductivity than resin, and therefore can reduce the thermal conductivity of the fire spread prevention sheet 1a in the thickness direction.

[0017] The mechanism by which the resin sheet 2 suppresses heat conduction between battery cells or from the battery cells to the housing will be described in more detail. The resin sheet 2 has a plurality of recesses 2a and / or holes 2b on its surface. Therefore, the area of ​​actual contact between the resin sheet 2 and the battery cells or the housing is smaller than the total area of ​​the resin sheet 2. Heat conduction from one battery cell to another battery cell or the housing occurs through the surface of the resin sheet 2 that contains air. Therefore, the amount of heat transferred from one battery cell to another battery cell or the housing is reduced.

[0018] As described above, the resin sheet 2 has recesses 2a and / or holes 2b. The shape and size of the recesses 2a and / or holes 2b are not particularly limited. Examples of the shape of the recesses 2a and / or holes 2b include a circle as shown in FIG. 1 , an ellipse, and polygons such as a triangle, a rectangle, a pentagon, a hexagon, and a star. The arrangement positions of the recesses 2a and / or holes 2b on the resin sheet 2 are not particularly limited. As shown in the figure, the recesses 2a and / or holes 2b may be uniformly arranged on the surface of the resin sheet 2. If the heat source has a portion that generates a large amount of heat, the recesses 2a and / or holes 2b may be concentrated on the surface portion of the resin sheet 2 that contacts that portion. The arrangement positions of the recesses 2a and / or holes 2b and the air layer formed will be described below.

[0019] FIG. 2 shows cross-sectional views (2A, 2B, 2C) taken along line AA of various variations of the resin sheet constituting the fire spread prevention sheet of FIG.

[0020] The resin sheet 2 shown in 2A preferably has a plurality of recesses 2a on one surface in the thickness direction. This allows the resin sheet 2 to retain a large amount of air on one surface in the thickness direction. Furthermore, the resin sheet 2 shown in 2B preferably has a plurality of recesses 2a on both surfaces in the thickness direction. This allows the resin sheet 2 to retain even more air on both surfaces in the thickness direction. Furthermore, the resin sheet 2 shown in 2C preferably has holes 2b penetrating in the thickness direction. This allows the resin sheet 2 to retain a large amount of air in the holes 2b penetrating in the thickness direction.

[0021] The greater the amount of air held in the recesses 2a and / or holes 2b per unit volume present in the resin sheet 2, the lower the thermal conductivity of the resin sheet 2 can be, and the more the conduction of heat from a heat source such as a battery cell to other battery cells or the housing can be suppressed.

[0022] The resin constituting the resin sheet 2 can be appropriately selected on the premise that it can form the recesses 2 a and / or holes 2 b and does not easily melt under normal use conditions of the battery, etc. The resin to be selected may be either a thermoplastic resin or a thermosetting resin.

[0023] Examples of thermoplastic resins include polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polycarbonate (PC). Among these, polyethylene terephthalate (PET) and polycarbonate (PC) are preferred, as they exhibit relatively high heat resistance. Thermoplastic resins with even higher heat resistance than the above-mentioned thermoplastic resins can also be suitably used, and examples of such thermoplastic resins include polyphenylene sulfide (PPS) and polyether ether ketone (PEEK).

[0024] Examples of thermosetting resins include silicone resins, epoxy resins, phenolic resins, unsaturated polyester resins, urea resins, melamine resins, diallyl phthalate resins, silicon resins, and vinyl ester resins.

[0025] (3) Heat Insulation Sheet The heat insulation sheet 3 is a sheet for enhancing the heat insulation properties of the fire prevention sheet 1a and has a lower thermal conductivity than the resin sheet 2. The heat insulation sheet 3 is laminated with the resin sheet 2. The heat insulation sheet 3 preferably contains a metal oxide. Examples of metal oxides include talc, diatomaceous earth, silica, silica aerogel, and mica. The heat insulation sheet 3 may contain a metal hydroxide, such as aluminum hydroxide and / or magnesium hydroxide, instead of or in addition to the metal oxide. The heat insulation sheet 3 may also contain a silicone rubber or silicone resin filler (including recycled products). The heat insulation sheet 3 exhibits a lower thermal conductivity than the resin sheet 2 by containing a heat insulating material, such as a metal oxide, metal hydroxide, and / or the silicone filler. The heat insulation sheet 3 may also be a sheet containing the heat insulating material in a resin. There are no particular restrictions on the mass ratio of the heat insulating material in the heat insulation sheet 3, but it is preferably 80 to 100 mass%, more preferably 85 to 99 mass%.

[0026] Examples of thermoplastic resins that can be used to form the heat insulating sheet 3 include polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate (PC), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). Among these, polyphenylene sulfide (PPS) and polyether ether ketone (PEEK) are preferred because of their high heat resistance.

[0027] Examples of the thermosetting resin that constitutes the heat insulating sheet 3 include silicone resin, epoxy resin, phenol resin, unsaturated polyester resin, urea resin, melamine resin, diallyl phthalate resin, silicon resin, and vinyl ester resin.

[0028] In addition to the above resins, the heat insulating sheet 3 may contain fibers made of resin or inorganic material, such as aramid fibers.

[0029] (4) Thickness of Fire Spread Prevention Sheet The total thickness of the fire spread prevention sheet 1a is not particularly limited. It can be appropriately selected depending on the type and size of the heat source in which the fire spread prevention sheet 1a is used, the size of the space in which the fire spread prevention sheet 1a is placed, the number of fire spread prevention sheets 1a to be used, etc. In consideration of the productivity and versatility of the fire spread prevention sheet 1a, the total thickness of the fire spread prevention sheet 1a is preferably 2 to 20 mm, more preferably 3 to 10 mm.

[0030] The thickness ratio of the resin sheet 2 to the heat insulating sheet 3 is preferably resin sheet 2:heat insulating sheet 3=1:1-5, and more preferably 1:2-4.

[0031] Second Embodiment FIG. 3 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a second embodiment.

[0032] The resin sheet 2 in the fire spread prevention sheet 1b according to this embodiment has a groove-shaped recess 2a connecting two opposing sides or radial ends of the resin sheet 2 in a plan view. The other structures and materials of the fire spread prevention sheet 1b are the same as those of the fire spread prevention sheet 1a, so redundant explanations will be omitted. Below, the differences between the fire spread prevention sheet 1b and the fire spread prevention sheet 1a will be further described.

[0033] The groove-shaped recesses 2a in the resin sheet 2 retain air and allow the air to flow out when pressure is applied from the battery cells or the like. This provides better insulation for the fire spread prevention sheet 1b than the fire spread prevention sheet 1a. Therefore, the fire spread prevention sheet 1b can further reduce heat conduction between battery cells or from the battery cells to the housing. Furthermore, the air in the recesses 2a can reduce the inhibition of shrinkage of the fire spread prevention sheet 1b in the thickness direction. Third Embodiment: Figure 4 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a third embodiment.

[0034] The fire spread prevention sheet 1c according to this embodiment includes the resin sheets 2 constituting the fire spread prevention sheet 1a on both thicknesswise sides of the heat insulating sheet 3. The other structure and materials of the fire spread prevention sheet 1c are the same as those of the fire spread prevention sheet 1a, so a duplicated explanation will be omitted. Below, the differences between the fire spread prevention sheet 1c and the fire spread prevention sheet 1a will be described.

[0035] The fire spread prevention sheet 1c includes one resin sheet 2 on each thickness-wise side of the heat insulating sheet 3, allowing air to be retained in the recesses 2a and / or holes 2b of each resin sheet 2. This enhances the heat insulation properties of the fire spread prevention sheet 1c compared to the fire spread prevention sheet 1a, which includes only one resin sheet 2. The fire spread prevention sheet 1c can further reduce heat conduction between battery cells or from the battery cells to the housing. Furthermore, the structure in which the heat insulating sheet 3 is sandwiched between the resin sheets 2 in the thickness direction further reduces the risk of some of the materials contained in the heat insulating sheet 3 scattering from the heat insulating sheet 3. Fourth Embodiment Figure 5 shows a plan view, a front view, and a side view of a fire spread prevention sheet according to a fourth embodiment.

[0036] The fire spread prevention sheet 1d according to this embodiment includes the resin sheets 2 constituting the fire spread prevention sheet 1b on both thicknesswise sides of the heat insulating sheet 3. The other structure and materials of the fire spread prevention sheet 1d are the same as those of the fire spread prevention sheet 1b, so a duplicated explanation will be omitted. Below, the differences between the fire spread prevention sheet 1d and the fire spread prevention sheet 1b will be described.

[0037] Because the fire spread prevention sheet 1d includes one resin sheet 2 on each side of the heat insulating sheet 3 in the thickness direction, air can be retained in the recesses 2a of each resin sheet 2. Therefore, compared to the fire spread prevention sheet 1b, which includes only one resin sheet 2, the fire spread prevention sheet 1d can further reduce heat conduction between battery cells or from the battery cell to the housing. Furthermore, the structure in which the heat insulating sheet 3 is sandwiched between the resin sheets 2 in the thickness direction can further reduce the risk of some of the materials contained in the heat insulating sheet 3 scattering from the heat insulating sheet 3. In addition, the air in the recesses 2a can further reduce the suppression of shrinkage of the fire spread prevention sheet 1d in the thickness direction.

[0038] 2. Manufacturing Method of Fire Spread Arrestor Sheet <First Embodiment> A manufacturing method of a fire spread arrestor sheet according to a first embodiment will be described. This manufacturing method includes a step of forming recesses 2a and / or holes 2b in a resin sheet 2, and a step of laminating the resin sheet 2 with the recesses 2a and / or holes 2b formed therein and a heat insulating sheet 3. The laminating step is not particularly limited, but examples include thermocompression bonding or bonding using an adhesive.

[0039] 6A and 6B are longitudinal cross-sectional views showing a process of manufacturing a resin sheet by pressing a plate against the plane of the resin sheet. The black arrows in the figures indicate the direction of movement of the plate 5. The white arrows in the figures indicate the flow of the manufacturing process.

[0040] As shown in FIG. 6A, recesses 2a are formed in the resin sheet 2 by pressing a plate 5 having projections and recesses onto the resin sheet 2. When manufacturing the fire spread prevention sheet 1a using a thermoplastic resin, the resin sheet 2 may be heated to a temperature equal to or higher than the softening point of the resin constituting the resin sheet 2 before pressing the plate 5 having the projections 5a onto the resin sheet 2. In this case, the temperature of the plate 5 during pressing may be room temperature (25°C to 30°C) or a temperature lower than the softening point. Alternatively, when using a resin sheet 2 made of a thermoplastic resin, the resin sheet 2 may be pressed by heating the plate 5 to a temperature equal to or higher than the softening point of the resin sheet 2 without heating the resin sheet 2. This softens the portions of the resin sheet 2 that come into contact with the plate 5, forming recesses 2a. The plate 5 is then removed from the resin sheet 2.

[0041] When producing the fire spread prevention sheet 1a using a thermosetting resin, the plate 5 is pressed against a curable resin sheet 2' that will cure to become the resin sheet 2. The plate 5 is preferably used in a state heated to the curing temperature of the curable resin sheet 2' or a temperature higher than that. As another production method, after pressing the plate 5 against the curable resin sheet 2', the curable resin sheet 2' and / or the plate 5 may be heated to the above-mentioned curing temperature or a temperature higher than that to cure the curable resin sheet 2'. After the curable resin sheet 2' has cured to become the resin sheet 2, the plate 5 is removed from the resin sheet 2.

[0042] In the process for manufacturing the resin sheet 2 shown in Fig. 6B, a plate 5 having higher protrusions 5a is used. Other conditions are the same as those in the process shown in Fig. 6A, so redundant explanations will be omitted. By using a plate 5 having higher protrusions 5a, holes 2b penetrating the resin sheet 2 in the thickness direction can be formed.

[0043] 7 is a longitudinal cross-sectional view showing a process of manufacturing a resin sheet by pressing plates against the top and bottom surfaces of the resin sheet. The black arrows in the figure indicate the direction in which the plates 5 move. The white arrows in the figure indicate the flow of the manufacturing process.

[0044] In the process for producing the resin sheet 2 shown in Figure 7, two plates 5 are used. The two plates 5 are pressed against both the top and bottom surfaces of the resin sheet 2 or the curable resin sheet 2'. Other conditions are the same as those in the process shown in Figure 6A, so redundant explanations will be omitted. This allows multiple recesses 2a and / or holes 2b to be formed on both sides of the resin sheet 2 in the thickness direction.

[0045] 8 is a vertical cross-sectional view showing the process of attaching a resin sheet to a heat insulating sheet 3. The black arrows in the figure indicate the direction in which the resin sheet 2 is attached to the heat insulating sheet 3. The white arrows in the figure indicate the flow of the manufacturing process.

[0046] The resin sheet 2 having the recesses 2a and / or holes 2b formed therein by the method shown in Fig. 6 or 7 can be bonded to the heat insulating sheet 3 by, for example, thermocompression bonding or bonding with an adhesive. Fig. 8 shows only the state in vertical cross section where the resin sheet 2 having the recesses 2a formed therein is bonded to the heat insulating sheet 3, but the method of bonding the resin sheet 2 having the holes 2b formed therein to the heat insulating sheet 3 is the same as the bonding method shown in Fig. 8.

[0047] To bond the resin sheet 2 and the heat insulating sheet 3, an adhesive is applied to the heat insulating sheet 3, and then the resin sheet 2 is placed on the adhesive-coated surface. For example, if a pressure-sensitive adhesive is used as the adhesive, pressure is applied from above to the resin sheet 2 placed on the heat insulating sheet 3. Alternatively, for example, if a heat-setting or hot-melt adhesive is used as the adhesive, the heat insulating sheet 3 and the resin sheet 2 placed on the heat insulating sheet 3 are heated to the hardening temperature or hot-melt temperature of the adhesive. This causes the resin sheet 2 to stick to the heat insulating sheet 3.

[0048] The resin sheet 2 can also be attached to the heat insulating sheet 3 by thermocompression bonding without using the above adhesive. However, it is necessary to ensure that the recesses 2a and / or holes 2b formed in the resin sheet 2 are not lost during the thermocompression bonding process.

[0049] To manufacture fire spread prevention sheets 1c and 1d each having resin sheets 2 on both thickness-wise sides of a heat insulating sheet 3, the heat insulating sheet 3 to which the resin sheet 2 has been attached is attached to the resin sheet 2 (not shown). Note that the conditions for the attachment process are the same as those for the above process, and therefore a redundant explanation will be omitted.

[0050] By using the above manufacturing processes, in addition to fire spread prevention sheets 1a, 1b, 1c, and 1d having multiple recesses 2a and / or holes 2b on one side of the resin sheet 2 in the thickness direction, fire spread prevention sheets 1a, 1b, 1c, and 1d having multiple recesses 2a and / or holes 2b on both sides of the resin sheet 2 can also be manufactured.

[0051] Second Embodiment Next, a description will be given of a method for manufacturing a fire spread prevention sheet according to a second embodiment. This manufacturing method includes the steps of overlapping a resin sheet 2 or a curable resin sheet 2′ with a heat insulating sheet 3, and pressing a plate 5 having projections and recesses from the side of the resin sheet 2 or the curable resin sheet 2′ to bond the resin sheet 2 and the heat insulating sheet 3 together and to form recesses 2 a and / or holes 2 b in the resin sheet 2.

[0052] 9 is a longitudinal cross-sectional view showing the heat treatment process when manufacturing a fire spread prevention sheet according to the second embodiment. The black arrows in the figure indicate the direction in which the resin sheet 2 or the curable resin sheet 2' is attached to the heat insulating sheet 3 and the direction in which the plate 5 moves. The white arrows in the figure indicate the flow of the manufacturing process.

[0053] When manufacturing a fire-spreading sheet 1a including a thermoplastic resin resin sheet 2, the resin sheet 2 and the heat insulating sheet 3 are first stacked. Next, a plate 5 having an uneven surface is pressed against the resin sheet 2. Before pressing the plate 5, the resin sheet 2 may be heated to a temperature above its softening point. In this case, the temperature of the plate 5 during pressing may be room temperature (25°C to 30°C) or a temperature lower than the softening point. Pressing may also be performed without heating the resin sheet 2, with the plate 5 heated to the softening point of the resin sheet 2 or higher. This softens the portions of the resin sheet 2 that come into contact with the plate 5, forming recesses 2a, and the heat insulating sheet 3 and the resin sheet 2 adhere to each other to form a single unit. The plate 5 is then removed from the fire-spreading sheet 1a. This manufacturing method is applicable not only to the fire-spreading sheet 1a but also to the fire-spreading sheet 1b.

[0054] In the process of manufacturing the fire spread prevention sheet 1a having the resin sheet 2 with the holes 2b, a plate 5 having higher convex portions 5a is used. The other conditions are the same as those for manufacturing the fire spread prevention sheet 1a having the resin sheet 2 with the concave portions 2a, so a duplicated explanation will be omitted.

[0055] To manufacture fire spread prevention sheets 1c and 1d, which include resin sheets 2 made of thermoplastic resin on both thickness-wise surfaces of the heat insulation sheet 3, two resin sheets 2 are stacked on both thickness-wise surfaces of the heat insulation sheet 3. Next, plates 5 (not shown) are pressed against the two curable resin sheets 2 from both outer sides. Note that the formation of recesses 2a and / or holes 2b and the attachment of the resin sheets 2 to the heat insulation sheet 3 are the same as in the manufacturing process for fire spread prevention sheets 1a and 1b, which include resin sheets 2 on only one thickness-wise surface of the heat insulation sheet 3, and therefore a duplicated explanation will be omitted.

[0056] On the other hand, when manufacturing the fire spread prevention sheet 1a using a thermosetting resin, the curable resin sheet 2' and the heat insulating sheet 3 are first stacked. The plate 5 is preferably used in a state heated to the curing temperature of the curable resin sheet 2' or higher. As another manufacturing method, the plate 5 may be pressed against the curable resin sheet 2', and then the curable resin sheet 2' and / or the plate 5 may be heated to the above-mentioned curing temperature or higher to cure the curable resin sheet 2'. When the curable resin sheet 2' cures to form the resin sheet 2, the resin sheet 2 and the heat insulating sheet 3 are integrated. The plate 5 is then removed from the laminate of the resin sheet 2 and the heat insulating sheet 3. In this way, a recess 2a is formed in the resin sheet 2. This manufacturing method is applicable not only to the fire spread prevention sheet 1a but also to the fire spread prevention sheet 1b.

[0057] In the process of manufacturing the fire spread prevention sheet 1a having the resin sheet 2 with the holes 2b, a plate 5 having higher convex portions 5a is used. The other conditions are the same as those for manufacturing the fire spread prevention sheet 1a having the resin sheet 2 with the concave portions 2a, so a duplicated explanation will be omitted.

[0058] To manufacture fire spread prevention sheets 1c and 1d, which include resin sheets 2 made of thermosetting resin on both thickness-wise surfaces of the heat insulation sheet 3, two curable resin sheets 2' are stacked on both thickness-wise surfaces of the heat insulation sheet 3. Next, plates 5 are pressed against the two curable resin sheets 2' from both outer sides (not shown). Note that the formation of recesses 2a and / or holes 2b, the curing of the curable resin sheets 2', and the integration of the resin sheets 2 and the heat insulation sheet 3 associated with this curing are common to the manufacturing processes for fire spread prevention sheets 1a and 1b, which include a curable resin sheet 2' on only one thickness-wise surface of the heat insulation sheet 3, and therefore a redundant description will be omitted.

[0059] These manufacturing processes cannot produce fire spread prevention sheets having a structure in which multiple recesses 2a and / or holes 2b are formed on both sides of a single resin sheet 2. However, the time required for the manufacturing process can be shortened because the resin sheet 2 can be attached to the heat insulating sheet 3 at the same time as the recesses 2a and / or holes 2b are formed in the resin sheet 2. Furthermore, the fire spread prevention sheets 1a, 1b, 1c, and 1d can be manufactured while reliably leaving the recesses 2a and / or holes 2b in the resin sheet 2.

[0060] 3. Battery Fig. 10 shows a longitudinal cross-sectional view of a battery according to one embodiment and an enlarged view of one fire prevention sheet sandwiched between battery cells in the longitudinal cross-sectional view.

[0061] The battery 10 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") 20 arranged side by side. In this embodiment, the number of battery cells 20 is eight, but may be two to seven, or nine or more. The battery 10 is a storage battery, preferably a lithium-ion battery. The battery 10 includes a housing 11 with a bottom that is open on one side. The battery cells 20 are disposed inside the housing 11 in an interior 12. The plurality of battery cells 20 are preferably pressed against each other by compressive force applied from both sides of the housing 11 using screws or the like (not shown). The bottom of the housing 11 is provided with a through-hole 13 for flowing cooling water, which is an example of a coolant. The coolant may also be referred to as a cooling medium or a coolant. The battery cells 20 are disposed within the housing 11 with fire-prevention sheets 1, collectively referred to as fire-prevention sheets 1a, 1b, 1c, and 1d, sandwiched between adjacent battery cells 20.

[0062] As described above, the battery 10 according to the present invention includes a plurality of battery cells 20 in the housing 11, and includes the fire spread prevention sheet 1 at least between the battery cells 20, either between the battery cells 20 or between the battery cells 20 and the housing 11. The fire spread prevention sheet 1 does not have to be disposed between the battery cells 20 and the housing 11.

[0063] The fire spread prevention sheet 1 arranged between the battery cells 20 is a sheet having a configuration in which a resin sheet 2 and a heat insulating sheet 3 are laminated in the thickness direction. The fire spread prevention sheet 1 is sandwiched between the battery cells 20 when the battery cells 20 are set in the housing 11.

[0064] The fire spread prevention sheet 1 used in the battery 10 can be selected appropriately depending on the internal environment of the housing 11 in which it is installed. For example, when the fire spread prevention sheet 1 is placed between the battery cell 20 and the housing 11, fire spread prevention sheets 1a and 1b having a resin sheet 2 on one surface of the heat insulating sheet 3 in the thickness direction may be used. When the fire spread prevention sheet 1 is placed between battery cells 20, fire spread prevention sheets 1c and 1d having a resin sheet 2 on both surfaces of the heat insulating sheet 3 in the thickness direction may be used.

[0065] 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.

[0066] The fire spread prevention sheets 1a and 1b may have only recesses 2a or only holes 2b in the resin sheet 2, or may have both recesses 2a and holes 2b. The same applies to the fire spread prevention sheets 1c and 1d. Two or more types of fire spread prevention sheets 1a, 1b, 1c, and 1d may be arranged inside the battery 10.

[0067] The features of the claims may be combined in any combination except where they are incombinable with one another.

[0068] The present invention can be used in the field of preventing the spread of fire caused by an overheated state of a heat source.

Claims

1. A fire prevention sheet that is placed at least between multiple heat sources and that can prevent the spread of fire by suppressing heat transfer to other heat sources when one of the heat sources is in an overheated state, the fire prevention sheet having a laminated structure of a resin sheet and a heat insulating sheet that has a lower thermal conductivity than the resin sheet, the resin sheet having holes that penetrate through the thickness direction and / or recesses that are recessed inward from the outer surface of the sheet.

2. A fire spread prevention sheet according to claim 1, characterized in that the resin sheet is provided on both sides of the heat insulating sheet in the thickness direction.

3. A fire prevention sheet according to claim 1 or 2, characterized in that the resin sheet is a sheet of polypropylene, polyvinyl chloride, polyethylene terephthalate or polycarbonate.

4. A fire prevention sheet according to any one of claims 1 to 3, characterized in that the heat insulating sheet is a sheet containing talc, diatomaceous earth, silica, silica aerogel or mica.

5. A method for manufacturing a fire spread prevention sheet according to any one of claims 1 to 4, comprising the steps of: forming the holes and / or recesses in the resin sheet; and laminating the resin sheet with the holes and / or recesses formed therein and the heat insulating sheet together.

6. A method for producing a fire spread prevention sheet according to any one of claims 1 to 4, comprising the steps of: overlapping the heat insulating sheet with the resin sheet or a curable resin sheet that will harden to become the resin sheet; and pressing a plate having irregularities from the side of the resin sheet or the curable resin sheet to attach the resin sheet and the heat insulating sheet together and form the holes and / or the recesses in the resin sheet.

7. A battery having a plurality of battery cells in a housing, characterized in that a fire prevention sheet according to any one of claims 1 to 4 is provided at least between the battery cells, either between the battery cells themselves or between the battery cells and the housing.

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