Fire-prevention cell unit, its manufacturing method, and battery

Abstract

To provide a fire spread prevention cell unit, a manufacturing method thereof, and a battery in which a fire spread prevention sheet which is easily deformable following overheat expansion of a battery cell and has excellent heat insulating properties in the battery cell.SOLUTION: A fire spread prevention cell unit 1 according to the present invention includes a battery cell 20 and a fire spread prevention sheet 10 affixed to the side surface located in the direction in which the battery cell 20 is arranged, and the fire spread prevention sheet 10 is a porous sponge sheet, and a hole 15 in the fire spread prevention sheet 10 is elongated, and in which the hole 15 is oriented along the surface of fire spread prevention sheet 10, and there are provided a manufacturing method thereof and a battery.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fire-spread-prevention cell unit having a fire-spread-prevention sheet in a battery cell, a manufacturing method thereof, and a battery having the fire-spread-prevention cell unit. [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 more and more popular, particularly in European countries such as France, the Netherlands, and Germany, as well as in China.

[0003] Various batteries such as the above-mentioned automobile batteries may go into thermal runaway due to some cause, and may cause fire, smoke, or the like. In recent years, automobile batteries in which a plurality of battery cells are arranged and mounted in a housing are known. In such a battery in which a plurality of battery cells are arranged and mounted, if fire or smoke occurs in one battery cell, the heat may be transferred to the surrounding battery cells, causing further malfunctions such as fire, smoke, and explosion. In order to minimize damage caused by such malfunctions, methods for making it difficult for heat from battery cells that have become abnormally hot to be transferred to the surrounding battery cells have been considered. For example, a method of providing a fire-prevention sheet such as a fire-resistant material or a heat insulating layer between a plurality of battery cells has been conventionally known (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-206604 A Summary of the Invention [Problem to be solved by the invention]

[0005] It is required that the fire prevention sheet has low hardness and is easily deformed because of the need to reduce damage to the sheet even if the battery cell expands due to overheating. In addition, it is preferable that the fire prevention sheet contains air in order to improve the heat insulation of the fire prevention sheet. In order to meet the above demand, the inventor of the present invention has come up with the idea of ​​providing a porous rubber sheet on the side of the battery cell and sandwiching the sheet between the battery cells. The inventor of the present invention has developed the porous rubber sheet to further improve the heat insulation of the porous rubber sheet and completed the present invention. The present invention also contributes to the achievement of 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 in consideration of the above-mentioned problems, and aims to provide a fire-spread prevention cell unit that is equipped with a fire-spread prevention sheet that is easily deformed in response to overthermal expansion of the battery cell and has excellent insulating properties, a manufacturing method for the same, and a battery. [Means for solving the problem]

[0007] (1) A fire-spread prevention cell unit according to one embodiment of the present invention for achieving the above object comprises: A battery cell; a fire prevention sheet attached to a side surface of the battery cell in a direction in which the battery cells are arranged; Equipped with The fire spread prevention sheet is a porous sponge sheet, The holes in the fire prevention sheet are elongated and oriented with their length along the surface of the fire prevention sheet. (2) In another embodiment of the fire spread prevention unit, the adhesion of the surface of the fire spread prevention sheet that is attached to the battery cell may preferably be higher than the adhesion of an outer surface that is located on the opposite side in the thickness direction of the fire spread prevention sheet to the adhesion surface. (3) In the fire-proof unit according to another embodiment, preferably, the fire-proof sheet may further include a flame retardant material. (4) In the fire prevention unit according to another embodiment, the fire prevention sheet may preferably be made mainly of silicone rubber. (5) In order to achieve the above object, a method for manufacturing a fire spread prevention type cell unit according to one embodiment is a method for manufacturing any one of the fire spread prevention type cell units described above, comprising the steps of: a clamping step of sandwiching the curable composition that becomes a fire spread prevention sheet after curing between plates; a hardening step of producing a sponge-like hardened body by foaming the mixture after the clamping step so that the length direction of the holes is oriented in the clamping direction between the plates; A sheet forming process in which the hardened body is formed into a sheet having a length direction of the hole along the surface of the fire spread prevention sheet; a step of attaching the fire spread prevention sheet after the sheet forming step to a side surface located in a direction in which the battery cells are arranged; Includes. (6) To achieve the above object, a battery according to one embodiment includes a plurality of fire-spread prevention cell units as described above arranged in a row. Effect of the Invention

[0008] According to the present invention, it is possible to provide a fire spread prevention cell unit in which a fire spread prevention sheet that is easily deformed in response to overheating expansion of a battery cell and has excellent heat insulation properties is provided in the battery cell, a manufacturing method thereof, and a battery. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view for explaining the configuration of a fire spread prevention cell unit according to an embodiment of the present invention. [Diagram 2] FIG. 2 shows a cross-sectional view taken along line AA of the fire-spread prevention cell unit of FIG. [Diagram 3] FIG. 3A shows the fire spread prevention cell unit of FIG. 1 as viewed from the outer surface side of the fire spread prevention sheet, and FIG. 3B shows a modified example of the fire spread prevention cell unit as viewed from the outer surface side. [Figure 4]FIG. 4 shows a flow of the manufacturing process for a fire spread prevention cell unit according to an embodiment of the present invention and cross-sectional views of a representative form in each process. [Diagram 5] FIG. 5 shows a diagram for explaining the method of the thermal conductivity test. [Figure 6] FIG. 6 shows a diagram for explaining the results of the thermal conductivity test (5 minutes after the start of heating). [Figure 7] FIG. 7 shows a diagram for explaining the results of the thermal conductivity test (30 minutes after the start of heating). [Figure 8] FIG. 8 shows perspective views of a state in which a fire spread prevention type cell unit is being loaded into a battery according to an embodiment, and a state after the loading has been completed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] 1. Fire-prevention cell unit First, a fire spread prevention type cell unit according to an embodiment of the present invention will be described with reference to the drawings.

[0012] Fig. 1 is a perspective view for explaining the configuration of a fire spread prevention cell unit according to an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line AA of the fire spread prevention cell unit in Fig. 1 and an enlarged view of a part B.

[0013] The fire-proof cell unit 1 according to this embodiment includes a battery cell 20 and a fire-proof sheet 10 attached to a side surface in the direction in which the battery cells 20 are arranged. More specifically, the fire-proof cell unit 1 is a unit formed by integrating the battery cell 20 with the fire-proof sheet 10 attached to at least one of the two side surfaces in the direction in which the battery cells 20 are arranged. The fire-proof sheet 10 is disposed between a plurality of battery cells 20 inside the battery, and is a sheet capable of preventing fire spread by suppressing heat transfer to other battery cells 20 when the battery cell 20 is in an overheated state. The fire-proof sheet 10 is used by attaching its widest surface to the battery cell 20. A single structure in which the fire-proof sheet 10 is attached to the battery cell 20 is referred to as the fire-proof cell unit 1. In this embodiment, the fire-proof sheet 10 is in close contact with the battery cell 20, and can be attached without an intervening layer such as an adhesive. There are no particular limitations on the thickness of the fire spread prevention sheet 10, but it is preferably 1 to 20 mm, and more preferably 2 to 8 mm.

[0014] In the fire spread prevention sheet 10, the adhesion of the surface 11 attached to the battery cell 20 is preferably higher than the adhesion of the outer surface 12 located on the opposite side of the thickness direction of the fire spread prevention sheet 10 from the adhesion surface 11. As a result, each fire spread prevention type cell unit 1 can be easily loaded into or removed from the battery. In this application, "adhesion" is interpreted as being different from "bonding" or "fixing" and as being in a state that can be repeatedly attached.

[0015] In this embodiment, the attachment surface 11 for attaching the fire spread prevention sheet 10 to the battery cell 20 is a surface having high smoothness and capable of being adhered closely with almost no air intervening between the attachment surface 11 and the widest surface (side surface) of the battery cell 20. The surface roughness of the attachment surface 11 is smaller than that of the outer surface 12 when compared in terms of the arithmetic mean height (Sa) based on "ISO 25178 Surface Texture."

[0016] When a value other than Sa is used as the standard, it is preferable to use the maximum height (Sz) based on "ISO 25178 Surface Texture" as the standard. The surface roughness of the attachment surface 11 is smaller than the surface roughness of the outer surface 12 when compared in terms of the maximum height (Sz) value based on "ISO 25178 Surface Texture". Note that Sa and Sz are measured while avoiding open holes 15 on the attachment surface 11 and the outer surface 12.

[0017] When the fire spread prevention sheet 10 is manufactured by molding, the roughness of the attachment surface 11 and the outer surface 12 can be easily obtained by transferring the roughness of the inner surface of the mold or the resin sheet placed in the mold. In addition, if the surface roughness of the outer surface 12 is to be increased, a blasting process in which fine particles are collided may be performed. In this way, when the surface roughness of the outer surface 12 is increased compared to the attachment surface 11, it becomes easy to load or pull out one fire spread prevention cell unit 1 from among the multiple fire spread prevention cell units 1 into or from the battery housing. This is because when the fire spread prevention cell unit 1 is loaded or pulled out, the fire spread prevention cell unit 1 is unlikely to adhere to the adjacent fire spread prevention cell unit 1. In particular, the multiple fire spread prevention cell units 1 in the battery are often compressed from the outside in the column direction of the fire spread prevention cell units 1 after being loaded into the battery. Even in such a case, if the surface roughness of the outer surface 12 is large, the situation in which the fire spread prevention cell units 1 adhere to each other can be reduced. Furthermore, making the attachment surface 11 smooth increases the adhesion between the fire spread prevention sheet 10 and the side surface of the battery cell 20, making it easier to load or pull out each fire spread prevention cell unit 1 into or from the battery.

[0018] The means for making the outer surface 12 less adhesive than the attachment surface 11 is not limited to providing a difference in surface roughness as described above, and other means may be used. As another means, for example, the fire spread prevention sheet 10 may be formed of two layers of sheets, and the sheet on the outer surface 12 side may be made harder than the sheet on the attachment surface 11 side.

[0019] In this embodiment, the fire spread prevention sheet 10 is approximately the same size as the widest surface (side surface) of the battery cell 20, but may be larger or smaller than the side surface. However, in order to enhance fire spread prevention, it is preferable that the fire spread prevention sheet 10 is the same size as or larger than the side surface of the battery cell 20.

[0020] In this embodiment, the fire spread prevention sheet 10 is a porous sponge sheet. This sponge sheet has holes 15 that are preferably 40 to 95 volume %, more preferably 60 to 90 volume %, of the total volume of the sheet. The air in the holes 15 of the sponge sheet provides the fire spread prevention sheet 10 with excellent heat insulation. Therefore, the fire spread prevention sheet 10 contributes to low thermal conductivity between adjacent battery cells 20. The holes 15 have an elongated shape, that is, an anisotropic shape, and the length direction of the holes 15 is oriented along the surface of the fire spread prevention sheet 10. The length direction of the holes 15 is a direction that forms an approximately right angle (90 degrees ± 5 degrees) with the thickness direction of the fire spread prevention sheet 10. However, some of the multiple holes 15 may have a shape other than an elongated shape, or may have an elongated shape but not oriented in a direction approximately perpendicular to the thickness direction. It is sufficient that 50% or more, preferably 70% or more, and more preferably 90% or more of the total number of holes 15 are elongated in shape and their longitudinal direction is oriented in a direction approximately perpendicular to the thickness direction of the fire prevention sheet 10.

[0021] As shown in Fig. 2, in the fire spread prevention sheet 10, the elongated holes 15 are oriented so that the length direction of the holes 15 faces the direction along the sheet surface. In this case, the thermal conductivity (S1) in the thickness direction of the fire spread prevention sheet 10 is lower than the thermal conductivity (S2) in the length direction of the holes 15 (the height direction of the battery cells 20 in Fig. 2). Therefore, the fire spread prevention sheet 10 can reduce the thermal conduction between adjacent battery cells 20.

[0022] The fire spread prevention sheet 10 is mainly made of resin or rubber, and preferably made of rubber. The rubber is, for example, a thermosetting elastomer such as silicone rubber, urethane rubber, isoprene rubber, ethylene propylene rubber, natural rubber, ethylene propylene diene rubber, nitrile rubber (NBR) or styrene butadiene rubber (SBR); a thermoplastic elastomer such as a urethane-based, ester-based, styrene-based, olefin-based, butadiene-based or fluorine-based elastomer, or a composite thereof. Of the rubbers, silicone rubber, which has relatively high heat resistance, can be used more preferably. The fire spread prevention sheet 10 is preferably made mainly of silicone rubber. The fire spread prevention sheet 10 is more preferably a porous sponge sheet made of silicone rubber. In this application, "mainly" or "main material" is interpreted as being more than 50% by mass of the entire constituent materials.

[0023] It is preferable that the fire spread prevention sheet 10 contains a flame retardant material to further improve the fire spread prevention performance. The flame retardant material is preferably one or more inorganic compounds such as carbon (including amorphous carbon and graphite), halides, phosphorus compounds, platinum, platinum complexes, magnesium hydroxide, and aluminum hydroxide. The flame retardant material is preferably contained in an amount of 0.5 to 20 mass %, more preferably 1 to 20 mass %, based on the total mass of the fire spread prevention sheet 10.

[0024] FIG. 3A shows the fire spread prevention cell unit of FIG. 1 as viewed from the outer surface side of the fire spread prevention sheet, and FIG. 3B shows a modified example of the fire spread prevention cell unit as viewed from the outer surface side.

[0025] In this embodiment, the direction of the longest side, the direction of the second longest side, and the direction of the shortest side of the battery cell 20 are referred to as the height direction, the width direction, and the thickness direction, respectively. In A, the holes 15 are oriented along the surface of the fire prevention sheet 10 and the length direction of the holes 15 is oriented in the height direction of the battery cell 20. On the other hand, in B, the holes 15 are oriented along the surface of the fire prevention sheet 10 and the length direction of the holes 15 is oriented in the width direction of the battery cell 20. In both cases A and B, the length direction of the holes 15 is approximately perpendicular to the thickness direction of the fire prevention sheet 10. Therefore, in both cases A and B, the fire prevention sheet 10 effectively contributes to reducing the thermal conductivity between the adjacent battery cells 20. The length direction of the holes 15 may be oriented between the height direction and the width direction of the battery cell 20, that is, in an oblique direction, in addition to the height direction and the width direction of the battery cell 20.

[0026] 2. Manufacturing method of fire-proof cell unit Next, a method for manufacturing a fire spread prevention cell unit according to an embodiment of the present invention will be described with reference to the drawings.

[0027] FIG. 4 shows a flow of the manufacturing process for a fire spread prevention cell unit according to an embodiment of the present invention and cross-sectional views of a representative form in each process.

[0028] The method for manufacturing the fire spread prevention type cell unit according to this embodiment is a method for manufacturing the above-mentioned fire spread prevention type cell unit 1, and includes a clamping step (S101), a hardening step (S102), a sheet forming step (S103), and an attachment step (S104). Each step will be described in detail below.

[0029] (1) Clamping process (S101) This step is a step of sandwiching the curable composition 26, which will become a fire spread prevention sheet after curing, between plates 25. The curable composition 26 is preferably capable of retaining its shape, and is, for example, in a semi-cured state that is not completely cured. The curable composition 26 sandwiched between plates 25 preferably has a cylindrical, rectangular column, or a similar shape. The curable composition 26 contains, for example, an organic foaming agent for foaming during curing. Examples of the foaming agent include azobisisobutyronitrile (AIBN) or azodicarbonamide (ADCA). As an example of a method that does not contain an organic foaming agent, there is a method of using a curable composition 26 in which thermally expandable resin beads are added to rubber. In this case, the resin beads become balloon-like during curing, and a sponge-like cured body can be obtained. As another example of a method that does not contain an organic foaming agent, there is a method of using a curable composition 26 in which air has been mixed into a non-foaming liquid rubber under high pressure. In this case, a sponge-like cured body can be obtained by curing the curable composition 26 under normal pressure. In any foaming method, in the clamping step, the foamable curable composition 26 is clamped from both sides by plates 25. There are no limitations on the material of the plates 25 as long as it is possible to maintain the shape of the curable composition 26 when it is cured, and for example, a metal plate such as an aluminum plate or a resin plate such as a polyethylene terephthalate plate can be used.

[0030] (2) Curing process (S102) This step is a step of producing a sponge-like cured body 27 by foaming the composition 26 so that the length direction of the holes 15 faces the clamping direction of the plates 25 after the clamping step. The side of the curable composition 26 is not in contact with the plates 25. Therefore, heat is transferred to the side faster than the upper and lower surfaces in contact with the plates 25. Therefore, the side region is easily cured before foaming. As a result, inside the curable composition 26, the holes 15 are easily oriented toward the plate 25 and become elongated. In this way, a sponge-like cured body 27 having elongated holes 15 in the direction of the plate 25 is completed. When a curable silicone rubber composition is used as the curable composition 26, the composition is heated in this step.

[0031] (3) Sheet forming process (S103) This step is a step of shaping the hardened body 27 after the hardening step into a sheet in a form in which the length direction of the holes 15 is oriented along the surface of the fire spread prevention sheet 10. An exemplary shaping method is a method of cutting out a sheet from the hardened body 27. Instead of cutting out, a cutting and / or polishing technique may be used. In addition, a step of making a difference in adhesion between the attachment surface 11 and the outer surface 12 of the fire spread prevention sheet 10 may be performed during this step or immediately after this step. When the outer surface 12 is processed to have a rougher surface than the attachment surface 11, a blasting treatment may be performed on the outer surface 12. When the attachment surface 11 is processed to have a smoother surface than the outer surface 12, the attachment surface 11 may be mirror-polished.

[0032] (4) Attachment process (S104) This step is a step of attaching the fire spread prevention sheet 10 after the sheet forming step to the side located in the arrangement direction of the battery cells 20. A typical attachment method is attachment without using any adhesive, but an adhesive or double-sided tape can also be interposed between the fire spread prevention sheet 10 and the side of the battery cells 20.

[0033] 3. Thermal Conductivity Test Next, the method and results of the thermal conductivity test with different hole directions will be described.

[0034] FIG. 5 shows a diagram for explaining the method of the thermal conductivity test.

[0035] First, a foamed silicone rubber test piece V (30 mm diameter × 10 mm thickness) with holes 15 long in the vertical direction and a foamed silicone rubber test piece H (30 mm diameter × 10 mm thickness) with holes 15 long in the horizontal direction were prepared and cut vertically to expose the cross section. A digital microscope (manufactured by Keyence Corporation) was used to observe the cross section. Measurements were also made using a specific gravity meter (manufactured by Alpha Mirage Corporation), and the specific gravity of both test pieces V and H was 0.23 g / cm 3It was confirmed that the specimens had a specific gravity of 100 mm. From this result, it was determined that the porosity of both specimens V and H was almost the same. Figure 5 shows cross-sectional photographs of both specimens V and H and diagrams showing them in schematic form. From the photographs and diagrams in Figure 5, it can be seen that specimen V has long holes 15 in the vertical direction, and specimen H has long holes 15 in the horizontal direction.

[0036] Fig. 6 shows a diagram for explaining the results of the thermal conductivity test (5 min after the start of heating), and Fig. 7 shows a diagram for explaining the results of the thermal conductivity test (30 min after the start of heating).

[0037] Both test pieces V and H were placed on the hot plate 30 and heated to about 150°C. In this test, both test pieces V and H were heated from the bottom. Figures 6 and 7 show the temperature distributions of both test pieces V and H photographed by a thermography camera 5 minutes (a) and 30 minutes (b) after the start of heating, respectively. Note that different test pieces were photographed in (a) and (b). The temperature distributions were observed using a thermography camera (manufactured by Nippon Avionics Co., Ltd.). The "cell grain direction" in Figures 6 and 7 refers to the long direction of the holes 15. The horizontal stripes in both test pieces V and H show the temperature distribution, with the zones closer to the hot plate 30 having higher temperatures.

[0038] Comparing the temperature distributions of both test specimens V and H, it was found that the temperature line of approximately 70°C (position indicated by the white arrow) was lower for test specimen H under both conditions, 5 minutes and 30 minutes after the start of heating (see the white line where the arrow is pointing). Similarly, when looking at the line of temperatures higher than 70°C, it was found that test specimen H was in a lower position. From this result, it was found that test specimen H, in which the holes 15 are longer in the horizontal direction, has a smaller heat conduction rate than test specimen V, in which the holes 15 are longer in the vertical direction.

[0039] 4. Battery Next, a battery according to an embodiment of the present invention will be described with reference to the drawings. The battery is loaded with the fire-spread prevention type cell unit 1 according to the embodiment described above.

[0040] FIG. 8 shows perspective views of a state in which a fire spread prevention type cell unit is being loaded into a battery according to an embodiment, and a state after the loading has been completed.

[0041] The battery 40 according to this embodiment is, for example, a battery for an electric vehicle, and includes a plurality of battery cells 20 arranged in a row. The number of the battery cells 20 is 12 in this embodiment, but may be 2 to 11 or 13 or more. The battery 40 is a storage battery, and is preferably a lithium-ion battery. The battery 40 includes a bottomed housing 41 that opens on one side. The battery cells 20 are arranged inside 44 of the housing 41. The battery cells 20 are preferably in close contact with each other in the housing 41 by being given a compressive force from both sides of the housing 41 using screws or the like (not shown). One or more water-cooled pipes 43 are provided on a bottom 42 (an example of a cooling portion) of the housing 41 to flow cooling water, which is an example of a coolant 45. The coolant 45 may be called a cooling medium or a coolant. The battery cells 20 are arranged in the housing 41 with a fire-proof sheet 10 sandwiched between adjacent battery cells 20. The fire-spread-prevention sheet 10 is attached to the battery cells 20 to form one fire-spread-prevention type cell unit 1. The fire-spread-prevention type cell unit 1 is loaded toward the interior 44 of the housing 41 (see the direction of arrow C).

[0042] The fire spread prevention sheet 10 arranged between the battery cells 20 is a porous sheet with the length direction of the holes 15 oriented in a direction parallel to the plane of the fire spread prevention sheet 10 and substantially perpendicular to the thickness direction of the fire spread prevention sheet 10. Therefore, the fire spread prevention sheet 10 can reduce thermal conduction when heat from an overheated battery cell 20 is conducted to an adjacent battery cell 20. As a result, the fire spread prevention sheet 10 becomes a sheet with a high fire spread prevention effect between the battery cells 20.

[0043] 5. Other embodiments Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment, and can be practiced in various modifications.

[0044] In the above embodiment, the comparison of the surface roughness of the attachment surface 11 and the outer surface 12 is performed using the arithmetic mean height (Sa) or maximum height (Sz) based on "ISO 25178 Surface Texture." However, instead of this, a similar comparison can be performed using the calculated mean roughness (Ra) or maximum height (Rz) based on JIS B 0601. In this case, the Ra (or Rz) of the attachment surface 11 is smaller than the Ra (or Rz) of the outer surface 12.

[0045] The length-to-short ratio (aspect ratio) of the holes 15 is not particularly limited as long as it exceeds 1, and is preferably 2 or more, and more preferably 3 or more.

[0046] It is preferable that the fire spread prevention sheet 10 can be repeatedly attached to the side surface of the battery cell 20. However, the fire spread prevention sheet 10 may be fixed to the side surface of the battery cell 20 so that it cannot be repeatedly attached.

[0047] The multiple components of each of the above-described embodiments can be freely combined, except for cases where they cannot be combined with each other. [Industrial Applicability]

[0048] The present invention can be used in the field of batteries. [Explanation of symbols]

[0049] Reference Signs List 1 Fire-proof cell unit, 10 Fire-proof sheet, 11 Application surface, 12 Outer surface, 15 Hole, 20 Battery cell, 25 Plate, 26 Curable composition, 27 Cured body, 40 Battery.

Claims

1. A battery cell; a fire prevention sheet attached to a side surface of the battery cell in a direction in which the battery cells are arranged; Equipped with The fire spread prevention sheet is a porous sponge sheet, The porous sponge sheet has a plurality of holes containing air inside the sheet, A fire-spread-preventive cell unit, wherein the holes have an elongated shape and are oriented with their length direction along the surface of the fire-spread-preventive sheet.

2. The fire spread prevention cell unit described in claim 1, characterized in that the adhesiveness of the surface of the fire spread prevention sheet that is attached to the battery cell is higher than the adhesiveness of the outer surface located on the opposite side of the fire spread prevention sheet in the thickness direction from the adhesive surface.

3. 3. The fire-spread prevention type cell unit according to claim 1, wherein the fire-spread prevention sheet further contains a flame retardant material.

4. 4. The fire spread prevention type cell unit according to claim 1, wherein the fire spread prevention sheet is made mainly of silicone rubber.

5. A method for producing the fire spread prevention type cell unit according to any one of claims 1 to 4, comprising the steps of: a clamping step of sandwiching the curable composition that becomes a fire spread prevention sheet after curing between plates; a hardening step of producing a sponge-like hardened body by foaming the mixture after the clamping step so that the length direction of the holes is oriented in the clamping direction between the plates; A sheet forming process in which the hardened body is formed into a sheet having a length direction of the hole along the surface of the fire spread prevention sheet; a step of attaching the fire spread prevention sheet after the sheet forming step to a side surface located in a direction in which the battery cells are arranged; A method for manufacturing a fire-spread prevention cell unit, comprising:

6. A battery comprising a plurality of the fire-spread-prevention cell units according to any one of claims 1 to 4 arranged side by side.

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