Heat transfer suppressing sheet and battery pack

Abstract

The utility model provides a heat transfer inhibition sheet and a battery pack, the battery pack is provided with the heat transfer inhibition sheet, the heat transfer inhibition sheet can further improve heat insulation, can inhibit damage caused by flying objects during thermal runaway, and can maintain the heat insulation. The heat transfer suppressing sheet (50) has a heat insulating material (10) and a mica sheet (51) laminated on at least one of a first surface (10a) and a second surface (10b) of the heat insulating material (10), the first surface (10a) and the second surface (10b) being orthogonal to the thickness direction. In addition, the battery pack (100) has a plurality of battery cells (20a, 20b, 20c) and the heat transfer suppression sheet (50), and the plurality of battery cells (20a, 20b, 20c) are connected in series or in parallel.

Description

Technical Field

[0001] The utility model relates to a heat transfer suppression sheet and a battery pack having the heat transfer suppression sheet. Background Art

[0002] In recent years, from the perspective of environmental protection, electric vehicles and hybrid vehicles driven by electric motors have been actively developed. These electric vehicles and hybrid vehicles are equipped with a battery pack composed of a plurality of battery cells connected in series or in parallel to serve as a power source for the driving electric motor.

[0003] In addition, the battery cells mainly use lithium-ion secondary batteries that have higher capacity and higher output than lead-acid batteries, nickel-metal hydride batteries, etc. Moreover, in the case of thermal runaway, such as a battery cell rapidly heating up and continuing to heat up due to internal short circuits, overcharging, etc. of the battery, the heat from the battery cell that has thermal runaway is transmitted to other adjacent battery cells, which may cause thermal runaway of other battery cells.

[0004] As a method of suppressing the propagation of heat from a battery cell that has undergone thermal runaway as described above, a method of interposing a member having a heat insulating property between the battery cells is generally performed.

[0005] For example, Patent Document 1 discloses a power storage device having: a power storage element (battery cell); a first plate and a second plate arranged on the side of the power storage element and arranged with their surfaces facing each other; and a low thermal conductivity layer arranged between the first plate and the second plate.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-211013 Utility Model Content

[0009] Problems to be solved by the utility model

[0010] In the power storage device described in the above-mentioned Patent Document 1, a low thermal conductivity layer such as air is formed between the first plate and the second plate. However, as in the above-mentioned power storage device, in the low thermal conductivity layer based on air, when the power storage element reaches a high temperature, air convection occurs, and sufficient thermal insulation cannot be obtained. Therefore, it is required that the heat transfer suppression sheet can maintain excellent thermal insulation even when the power storage element is damaged and scattered.

[0011] The utility model is completed in view of the above-mentioned problems, and its purpose is to provide a heat transfer suppression sheet and a battery pack having the heat transfer suppression sheet, wherein the heat transfer suppression sheet can further improve the thermal insulation and can suppress the damage caused by flying objects during thermal runaway and can maintain the thermal insulation.

[0012] Means used to solve problems

[0013] The above-mentioned object of the present invention is achieved by the following structure [1] of the heat transfer suppression sheet.

[0014] [1] A heat transfer suppression sheet, characterized in that it has:

[0015] Insulation materials, and

[0016] A mica sheet is laminated on at least one of a first surface and a second surface perpendicular to the thickness direction of the thermal insulation material.

[0017] In addition, preferred embodiments of the present invention of the heat transfer suppression sheet relate to the following [2] to [9].

[0018] [2] The heat transfer suppression sheet described in [1], wherein the heat insulating material has a plurality of three-dimensionally connected pores.

[0019] [3] The heat transfer suppression sheet described in [1], wherein the heat insulating material has a welded portion.

[0020] [4] The heat transfer suppression sheet described in [3] is characterized in that the heat insulating material has a fiber layer including the welded portion on at least a portion of the first surface and the second surface.

[0021] [5] The heat transfer suppressing sheet described in [4] is characterized in that the fiber layer extends in a stripe shape in a direction substantially parallel to the surface of the heat insulating material.

[0022] [6] The heat transfer suppression sheet as described in [1] is characterized in that the surface of the above-mentioned insulating material has a first region and a second region, and the above-mentioned first region and the above-mentioned second region form an island structure, and the above-mentioned first region corresponding to the sea part surrounds the above-mentioned second region corresponding to the island part.

[0023] [7] The heat transfer suppressing sheet described in [1] is characterized in that fiber bundles extending in stripes and having a length of 20 mm or more are present on the surface of the thermal insulation material.

[0024] [8] The heat transfer suppressing sheet described in [7] is characterized in that the fiber bundles are connected in a mesh shape.

[0025] [9] The heat transfer suppression sheet as described in [1], characterized in that the thickness of the heat transfer suppression sheet is not less than 0.05 mm and not more than 10 mm.

[0026] In addition, the above-mentioned object of the present invention is achieved by the following structure

[10] of the battery pack.

[0027]

[10] A battery pack comprising a plurality of battery cells and the heat transfer suppressing sheet according to any one of [1] to [9], wherein the plurality of battery cells are connected in series or in parallel.

[0028] Effect of utility model

[0029] The heat transfer suppression sheet of the utility model has an insulating material including inorganic particles and organic fibers or inorganic fibers, so it can obtain excellent thermal insulation. In addition, since the mica sheet is stacked on the insulating material, the mica sheet can be used to protect the insulating material when, for example, a battery cell is damaged and scattered. Therefore, the insulating material can be prevented from being damaged by the scattered objects, and the thermal insulation can be maintained.

[0030] The battery pack of the present invention has a heat transfer suppression sheet as described above. The heat transfer suppression sheet has high thermal insulation and can maintain high thermal insulation even when the battery cells are damaged and scattered. Therefore, it is possible to suppress thermal runaway of the battery cells in the battery pack and suppress the spread of flames to the outside of the battery case. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic cross-sectional view showing a heat transfer suppression sheet according to an embodiment of the present invention.

[0032] Figure 2 This is a cross-sectional view schematically showing a battery pack including a heat transfer suppression sheet according to an embodiment of the present invention.

[0033] Figure 3 This is a photograph in place of a drawing showing a structural example 1 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention.

[0034] Figure 4 Yes Figure 3 A portion of the heat insulating material is shown enlarged in place of a photograph of the accompanying drawing.

[0035] Figure 5 This is a photograph in place of a drawing showing a structural example 2 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention.

[0036] Figure 6 This is a schematic diagram showing a structural example 3 of a heat insulating material used in the heat transfer suppression sheet according to the embodiment of the present invention.

[0037] Figure 7 Yes Figure 6 A schematic diagram showing an enlarged portion of the diagram.

[0038] Figure 8 It is shown Figure 6 Photographs of the insulation material shown.

[0039] Fig. 9 It is a photograph in place of a drawing showing a structural example 4 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention.

[0040] Fig.10 It is enlarged to show Fig. 9 The structure of the thermal insulation material is shown in the accompanying drawings in place of a photograph.

[0041] Fig.11 It is shown Fig. 9 A photograph of a cross section of the thermal insulation material is shown in the accompanying drawings.

[0042] Fig.12 This is a schematic diagram showing a structural example 5 of a heat insulating material used in the heat transfer suppression sheet according to the embodiment of the present invention.

[0043] Fig.13 It is enlarged to show Fig.12 Schematic diagram of portion A of the insulation material shown.

[0044] Fig.14 It is a photograph in place of a drawing showing a structural example 6 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention.

[0045] Fig.15 It is shown Fig.14 Additional areas of insulation are shown in the accompanying drawings in lieu of photographs.

[0046] Fig.16 It is shown Fig.14 and Fig.15 A photograph of a cross section of the thermal insulation material is shown in the accompanying drawings.

[0047] Fig.17 This is a photograph in place of a drawing showing a structural example 7 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention.

[0048] Fig.18A It is enlarged to show Fig.17 A photographic representation of a portion of the insulation material shown.

[0049] Fig.18B It is a schematic representation Fig.18A The drawings shown are diagrams in lieu of photographs.

[0050] Fig.19This is a schematic diagram showing an example of a method for defining the length of a fiber bundle.

[0051] Fig. 20 It is shown Fig.17 The following are photographs in lieu of drawings showing other structural examples of the heat insulating material. DETAILED DESCRIPTION

[0052] The present inventors have found that the above-mentioned problems can be solved by configuring a heat transfer suppressing sheet including a heat insulating material containing inorganic particles and organic fibers or inorganic fibers, and a mica sheet laminated on the heat insulating material.

[0053] The following is a detailed description of a heat transfer suppression sheet, a manufacturing method thereof, and a battery pack according to an embodiment of the present invention. It should be noted that the present invention is not limited to the embodiments described below, and can be implemented with any changes without departing from the gist of the present invention. First, the heat transfer suppression sheet according to an embodiment of the present invention is described.

[0054] [Heat transfer suppression sheet]

[0055] Figure 1 Schematic cross-sectional view showing a heat transfer suppression sheet according to an embodiment of the present invention. Figure 1 As shown, the heat transfer suppression sheet 50 of this embodiment has an insulating material 10, and a mica sheet 51 stacked on a first surface 10a and a second surface 10b perpendicular to the thickness direction of the insulating material 10. The insulating material 10 has inorganic particles and organic fibers or inorganic fibers not shown. The insulating material 10 is described in detail below. The mica sheet 51 is formed by processing a mica sheet material containing mica into a sheet shape.

[0056] As a specific use of the heat transfer suppression sheet 50, Figure 2 As shown, the heat transfer suppression sheet 50 can be used in a manner where it is sandwiched between a plurality of battery cells 20a, 20b, 20c. Furthermore, the plurality of battery cells 20a, 20b, 20c are housed in a battery case 30 in a state where they are connected in series or in parallel (the connected state is not shown in the figure), thereby forming a battery pack 100. It should be noted that the battery cells 20a, 20b, 20c can be appropriately lithium-ion secondary batteries, for example, but are not particularly limited thereto and can also be applied to other secondary batteries.

[0057] In the heat transfer suppression sheet 50 of the present embodiment constructed as described above, since it has the insulating material 10 containing inorganic particles and organic fibers or inorganic fibers, excellent thermal insulation can be obtained. Therefore, for example, when an abnormality occurs in the battery cell 20a and the temperature rises, the propagation of heat to the battery cell 20b can be fully suppressed. In addition, in the present embodiment, the mica sheet 51 is stacked on the first surface 10a and the second surface 10b of the insulating material 10. Mica has excellent heat resistance and insulation properties. In addition, the mica sheet 51 obtained by processing the material containing mica into a sheet shape is also excellent in impact resistance. Therefore, for example, when the battery cell 20a is broken due to high temperature and scattered objects are generated, the mica sheet 51 can be used to protect the insulating material 10, so that the insulating material 10 can be suppressed from being damaged. As a result, high thermal insulation can be maintained between the battery cell 20a and the battery cell 20b.

[0058] It should be noted that, in the present embodiment, the mica sheet 51 is stacked on the first surface 10a and the second surface 10b of the insulating material 10, but the present invention is not limited to such a structure. In the case where the insulating material 10 is desired to protect only one side of the heat transfer suppression sheet 50 from impact, the mica sheet 51 can be arranged on at least one side of the first surface 10a and the second surface 10b of the insulating material 10. In addition, the mica sheet 51 can also be arranged in a manner of being sandwiched between a pair of insulating materials 10. Regardless of the structure, the influence of scattered objects on the insulating material, other adjacent battery cells, etc. can be suppressed, and high thermal insulation can be obtained and the thermal insulation can be maintained.

[0059] In this embodiment, the heat insulating material 10 only needs to include inorganic particles and organic fibers or inorganic fibers (that is, at least one of organic fibers and inorganic fibers). An example of the heat insulating material 10 having even better heat insulating properties will be described in detail below.

[0060] <Heat insulation material (Structural example 1)>

[0061] Figure 3 This is a photograph in lieu of a drawing showing a structural example 1 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Figure 4 It is enlarged to show Figure 3 A photographic representation of a portion of the insulation material shown.

[0062] like Figure 3 and Figure 4As shown, the heat insulating material 10 in the heat insulating material (structure example 1) has inorganic particles 4 and organic fibers 1. In addition, the heat insulating material 10 has a plurality of three-dimensionally connected pores 7 between the inorganic particles 4 and the organic fibers 1. It should be noted that the organic fiber 1 has a cladding portion 5 covering at least a portion of the surface, and at least a portion of the inorganic particles 4 is clad to the surface of the organic fiber 1 by the cladding portion 5. As a result, the surface of the organic fiber 1 is covered with the inorganic particles 4.

[0063] In the insulating material 10 constructed in this way, since there are a plurality of three-dimensionally connected pores 7, an air-based insulation effect can be obtained, and the insulation performance can be improved. In addition, since the insulating material 10 contains organic fibers 1 having high flexibility, the flexibility of the insulating material 10 can be improved, and the organic fibers 1 are easily entangled with each other, which can achieve the effect of improving the strength of the sheet. In addition, by the presence of pores 7 in the insulating material 10, the buffering characteristics of the entire sheet are improved, so when the battery cells 20a, 20b, and 20c expand during charging and discharging, the insulating material 10 can absorb the expansion of the battery cells. Therefore, the destruction of the heat transfer suppression sheet having such an insulating material 10 can be suppressed.

[0064] In addition, in the present embodiment, it is preferred that at least a portion of the pores 7 is connected to the surface of the heat insulating material 10 and is open to the outside. If the pores 7 are configured in this way, when thermal runaway occurs in the adjacent battery cells 20a, 20b, 20c, even if the heat insulating material 10 reaches a high temperature and the organic fiber 1 decomposes, the decomposition gas does not remain inside the sheet but is released to the outside through the pores 7. Therefore, from this aspect, the effect of preventing the sheet from being destroyed can also be obtained.

[0065] In addition, when the cladding portion 5 on the outer peripheral surface of the organic fiber 1 fixes the inorganic particles 4 to the organic fiber 1, the effect of suppressing the falling off (powder falling off) of the inorganic particles 4 can be obtained. Therefore, even if, for example, a part of the battery cells 20a, 20b, 20c expands and applies compressive stress or impact to the heat transfer suppression sheet 50, the effect of maintaining the shape of the heat insulating material 10 can be further improved, and the reduction of the heat insulating effect due to the compression deformation of the heat insulating material 10 can be prevented.

[0066] In this specification, the cladding portion 5 refers to a portion of the surface of the organic fiber 1 that is melted and then solidified again, and is formed in the manufacturing process of the thermal insulation material 10 described later. In this embodiment, since the inorganic particles 4 are clad to the surface of the organic fiber 1 by the cladding portion 5, the apparent fiber diameter of the organic fiber 1 becomes thicker, which can support the shape of the thermal insulation material 10 and obtain high strength.

[0067] It should be noted that the cladding portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, and there may be a region where the cladding portion 5 does not exist. In the thermal insulation material 10, as the material of the organic fiber 1, a binder fiber of a core-sheath structure described later may be used. If the sheath is peeled off during the manufacturing process, the organic fiber 1 as the core may be partially exposed. Even in such a case, the effect of retaining the inorganic particles 4 can be fully obtained.

[0068] In addition, the heat insulating material 10 in the heat insulating material (configuration example 1) preferably further contains inorganic fibers. The effects obtained by containing inorganic fibers will be described in the following "heat insulating material (configuration example 2)".

[0069] <Heat insulation material (Structural example 2)>

[0070] Figure 5 This is a photograph in place of a drawing showing a structural example 2 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Figure 5 In the structural example 2 shown in FIG. Figure 3 and Figure 4 The same parts as those in the structural example 1 are marked with the same reference numerals, and detailed description is omitted. Figure 5 The heat insulating material 40 shown is used instead of Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0071] like Figure 5 As shown, the heat insulating material 40 has inorganic fibers 15. In addition, the heat insulating material 40 has a fiber layer 11 formed on at least a portion of the first surface 40a and the second surface (not shown) perpendicular to the thickness direction thereof. The fiber layer 11 is formed by cladding at least a portion of a plurality of organic fibers 1 with each other by a cladding portion and formed in a layered manner on the surface (the first surface and the second surface) of the heat insulating material 40. That is, the fiber layer 11 is a layer formed by assembling more than 10 organic fibers 1 on the surface of the heat insulating material 40, and extending in a direction substantially parallel to the surface, for example, in a stripe shape.

[0072] In addition, a composite layer (not shown) in which a part of the fiber layer 11 and a part of the inorganic particles 4 are mixed is formed between the fiber layer 11 and the base layer 13 including the inorganic particles 4 and the organic fibers 1. Specifically, the composite layer is a region including a plurality of organic fibers 1 at least partially fused to each other by the cladding portion, and inorganic particles 4 clad to the organic fibers 1 by the cladding portion.

[0073] It should be noted that in Figure 5 In the illustrated heat insulating material 40 , the inorganic fibers 15 are contained in the base layer 13 including the inorganic particles 4 and the organic fibers 1 , but may be contained in the fiber layer 11 . Figure 5In the figure, the inorganic fibers 15 in the fiber layer 11 cannot be distinguished and are therefore not shown.

[0074] In addition, the heat insulating material 40 has a fiber bundle 6 formed by at least a portion of a plurality of organic fibers 1 being fused together by the fusion-bonding portion 5. The fiber bundle 6 is formed by interweaving ten or more organic fibers 1 and partially fusion-bonding the organic fibers 1, and is arranged in an arbitrary direction in the heat insulating material 40.

[0075] The heat insulating material 40 thus constructed includes the inorganic fibers 15 which are not easily decomposed even at high temperatures. Therefore, for example, when the battery cell 20a undergoes thermal runaway and the heat transfer suppression sheet 50 disposed adjacent to the battery cell 20a is exposed to high temperatures, even if the organic fibers 1 in the heat insulating material 40 decompose, the inorganic fibers 15 remain, and thus the shape of the heat insulating material 40 can be reliably maintained.

[0076] In addition, since the flexible organic fibers 1 are easily entangled with the relatively hard inorganic fibers 15 and a three-dimensional skeleton is formed by the inorganic fibers 15 and the organic fibers 1 , the strength of the heat insulating material 40 can be further improved.

[0077] In addition, in the "thermal insulation material (structural example 2)", the thermal insulation material 40 has organic fibers 1 in addition to the inorganic fibers 15. However, even in the case where there is no organic fiber 1 and only inorganic particles 4 and inorganic fibers 15, the inorganic fibers 15 as described above still remain, and the effect of being able to reliably maintain the shape of the thermal insulation material 40 can of course be obtained.

[0078] In addition, when the insulating material 40 has both organic fibers 1 and inorganic fibers 15, it is particularly preferred that the effects of "since it contains organic fibers 1 having high flexibility, the flexibility of the insulating material 10 can be improved, and the organic fibers 1 are easily entangled with each other, which can improve the strength of the sheet" and "when the heat transfer suppression sheet 50 is exposed to high temperature, even if the organic fibers 1 in the insulating material 40 decompose, the inorganic fibers 15 still remain, so that the shape of the insulating material 40 can be reliably maintained" can be simultaneously exerted.

[0079] Furthermore, if the heat insulating material 40 has the fiber layer 11 on its surface and the fiber bundle 6 inside, a higher strength can be obtained compared with the case where the organic fiber 1 is dispersedly arranged. It should be noted that since the fiber layer 11 is not simply arranged on the base layer 13, but a composite layer in which a part of the fiber layer 11 and a part of the inorganic particles 4 are mixed exists between the fiber layer 11 and the base layer 13, the fiber layer 11 is surely constrained on the surface of the heat insulating material 40. Therefore, the fiber layer 11 alone does not fall off, and a heat insulating material 40 with high strength can be obtained. Since the mica sheet is stacked on the heat insulating material 40, a further excellent strength can be obtained.

[0080] Furthermore, if the fiber layer 11 is formed on the surface of the heat insulating material 40 , the fiber layer 11 can absorb the impact applied to the heat insulating material 40 , thereby achieving an effect of preventing the inorganic particles contained in the heat insulating material 40 from falling off.

[0081] <Heat insulation material (Structural example 3)>

[0082] Figure 6 1 is a schematic diagram showing a structural example 3 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Figure 7 It is enlarged to show Figure 6 In addition, Figure 8 It is shown Figure 6 Substitute photographs of the insulation material shown. Figure 6 to Figure 8 In the structural example 3 shown in FIG. Figure 3 and Figure 4 The same parts as those in the structural example 1 are marked with the same reference numerals, and detailed description is omitted. Figure 6 to Figure 8 The heat insulating material 60 shown is used instead Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0083] like Figure 6 to Figure 8 As shown, the thermal insulation material 60 of the present embodiment has inorganic particles 4, organic fibers 1 composed of a first organic material, and a cladding portion 5 covering the outer peripheral surface of the organic fiber 1. As described above, the cladding portion 5 contains a second organic material 17 having a melting point lower than that of the first organic material, and the inorganic particles 4. It should be noted that, in the present embodiment, as the organic fiber, an adhesive fiber 3 having a core-sheath structure having a core portion and a sheath portion covering the outer peripheral surface of the core portion is used, and the organic fiber 1 corresponds to the core portion. In addition, the cladding portion 5 is formed by temporarily melting the sheath portion of the adhesive fiber 3 having the core-sheath structure by heating, and then cooling it. In addition, as Figure 8As shown, the fiber portion 16 is formed by the organic fiber 1 and the cladding portion 5 containing the inorganic particles 4, and the matrix portion 18 containing the inorganic particles is formed between the plurality of fiber portions 16. In addition, when the molten sheath portion is cooled, the adjacent organic fibers 1 are fused to each other at the contact portion 31 to form a three-dimensional skeleton.

[0084] In the heat insulating material 60 constructed as described above, the organic fibers 1 and the cladding portion 5 function as a skeleton, so that excellent strength and shape retention can be obtained. In addition, the cladding portion 5 covering the outer peripheral surface of the organic fibers on both the surface side and the center side of the heat insulating material 60 fixes the inorganic particles 4 to the organic fibers 1, so that powder shedding can be suppressed. Therefore, for example, when the heat transfer suppression sheet 50 of this embodiment is arranged between a plurality of battery cells, even when the battery cells expand and apply compressive stress or impact to the heat transfer suppression sheet 50, excellent heat insulation performance can be maintained.

[0085] In the above-mentioned heat insulating material 60, the mechanism for suppressing the falling off (powder falling off) of the inorganic particles 4 is not clear, and one of the reasons is considered to be that the organic fibers 1 and the cladding portion 5 form a strong three-dimensional skeleton to maintain the shape of the heat insulating material 60, thereby suppressing the deformation or compression of the heat insulating material 60. In addition, regardless of whether there is a mica sheet 51 on the surface of the heat insulating material 60, the fiber portion 16 exposed on the surface of the heat insulating material 60 can absorb the impact given to the heat insulating material 60, and this is considered to be the reason why the inorganic particles 4 can be retained.

[0086] It should be noted that if Figure 8 As shown, in the heat insulating material 60, the cladding portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, but the organic fiber 1 may be partially exposed. Since the binder fiber 3 of the core-sheath structure is used in the heat insulating material 60, the sheath portion may be peeled off during the manufacturing process of the heat insulating material 60, but even when the organic fiber 1 is partially exposed, the effect of the present invention can be fully obtained.

[0087] <Heat insulation material (Structural example 4)>

[0088] Fig. 9 This is a photograph in lieu of a drawing showing a structural example 4 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Fig.10 It is enlarged to show Fig. 9 The structure of the thermal insulation material is shown in the accompanying drawings in place of a photograph. Fig.11 It is shown Fig. 9 The following is a substitute photograph of a cross section of the insulation material shown. Figures 9 to 11 In the structural example 4 shown in FIG. Figure 3 and Figure 4 The same parts as those in the structural example 1 are marked with the same reference numerals, and detailed description is omitted. Figures 9 to 11The heat insulating material 70 shown is used instead of Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0089] like Fig. 9 and Fig.10 As shown, the heat insulating material 70 has a matrix 14 including inorganic particles 4, and organic fibers 1 three-dimensionally oriented in the matrix 14. Furthermore, the organic fibers 1 have a cladding portion 5 covering at least a portion of the surface, and the organic fibers 1 are clad with each other by the cladding portion 5. Similarly, the inorganic particles 4 are also clad on the surface of the organic fibers 1, thereby forming a structure in which the surface of the organic fibers 1 is covered with the inorganic particles 4.

[0090] In addition, if Fig.11 As shown in the cross-sectional view of FIG. 1 , a plurality of pores 7 are formed in the matrix 14 of the heat insulating material 70. In addition, in the matrix 14, at least a portion of the plurality of organic fibers 1 are connected to each other by Fig.11 The fiber bundle 6 is formed by melting the melt-coated portion 5 (not shown), and gaps 8 are formed between the plurality of organic fibers 1 constituting the fiber bundle 6.

[0091] In addition, a fiber layer 11 is formed on at least a portion of the first surface 70a orthogonal to the thickness direction of the insulating material 70 and the second surface (not shown). The fiber layer 11 is formed on the surface (the first surface and the second surface) of the insulating material 70 by cladding at least a portion of the plurality of organic fibers 1 with each other using the cladding portion 5. In addition, a composite layer 12 is formed between the fiber layer 11 and the base layer 13 including the matrix 14 and the organic fibers 1. The composite layer 12 is a layer in which a portion of the fiber layer 11 and a portion of the matrix 14 are mixed. Specifically, the composite layer 12 is a region including a plurality of organic fibers 1 at least a portion of which are clad with each other using the cladding portion 5, and inorganic particles 4 clad to the organic fibers 1 using the cladding portion 5.

[0092] It should be noted that the fiber bundle 6 is formed by interweaving more than ten organic fibers 1 and partially fusion-coating the organic fibers 1, and is arranged in an arbitrary direction in the matrix 14 of the heat insulating material 70. On the other hand, the fiber layer 11 is a layer formed by assembling more than ten organic fibers 1 on the surface of the heat insulating material 70, and extends in a direction substantially parallel to the surface, for example, in a stripe shape.

[0093] In the heat insulating material 70 thus constituted, the organic fibers 1 are three-dimensionally oriented in the matrix 14, and the organic fibers 1 have a cladding portion 5 covering at least a portion of the surface. The cladding portion 5 is a portion where the surface of the organic fiber 1 is melted and then solidified again, and is formed during the manufacturing process of the heat insulating material 70. In the heat insulating material 70, the three-dimensionally oriented organic fibers 1 are clad with each other by the cladding portion 5, so that the structure becomes a skeleton and supports the shape of the heat insulating material 70, and high strength can be obtained.

[0094] Similarly, in the heat insulating material 70, the cladding portion 5 on the outer peripheral surface of the organic fiber 1 also fixes the inorganic particles 4 to the organic fiber 1, so that a higher powder falling-off suppression effect can be obtained. Therefore, for example, during the charge and discharge of the battery cells 20a, 20b, and 20c, even if a part of them expands and applies compressive stress or impact to the heat transfer suppression sheet 50, the shape of the heat insulating material 70 can be maintained. As a result, the falling off (powder falling off) of the inorganic particles 4 can be suppressed, and the reduction of the heat insulating effect due to the compression deformation of the heat insulating material 70 can be prevented.

[0095] The mechanism by which the inorganic particles 4 can be suppressed from falling off from the sheet surface in the heat insulating material 70 is considered to be the same as that of the heat insulating material 60 in the above-mentioned configuration example 3.

[0096] It should be noted that in the heat insulating material 70, the cladding portion 5 does not necessarily have to completely cover the outer peripheral surface of the organic fiber 1, and there may be a partial area where the cladding portion 5 does not exist. Even in such a case, the effect of retaining the inorganic particles 4 can be fully obtained.

[0097] Furthermore, since the heat insulating material 70 includes the highly flexible organic fibers 1 , the flexibility of the heat insulating material 70 can be improved, and the organic fibers 1 are easily entangled with each other, thereby achieving an effect of improving the sheet strength.

[0098] In addition, in the heat insulating material 70, since the plurality of pores 7 are provided in the matrix 14 and the gaps 8 are provided between the plurality of organic fibers 1 constituting the fiber bundle 6, the heat insulating performance can be improved. In addition, due to the presence of the gaps 8, the organic fibers 1 are not easily constrained in the matrix 14, so that the flexibility and strength of the heat insulating material 70 can be further improved. The gaps 8 do not need to be formed in the entire region between the plurality of organic fibers 1, and as long as the gaps 8 are formed in at least a portion between the organic fibers 1, the heat transfer suppression effect can be obtained.

[0099] Furthermore, since the heat insulating material 70 includes the fiber bundle 6 and the fiber layer 11, it is possible to obtain a higher strength than when the organic fibers 1 are dispersedly arranged. In addition, since the fiber layer 11 is not simply arranged on the base layer 13, but a composite layer 12 in which a part of the fiber layer 11 and a part of the inorganic particles 4 constituting the matrix 14 are mixed exists between the fiber layer 11 and the base layer 13, the fiber layer 11 is surely constrained on the surface of the heat insulating material 70. Therefore, a heat insulating material 70 having high strength can be obtained.

[0100] <Heat insulation material (Structural example 5)>

[0101] Fig.121 is a schematic diagram showing a structural example 5 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Fig.13 It is enlarged to show Fig.12 Schematic diagram of portion A of the insulation material shown. Fig.12 and Fig.13 In the structural example 5 shown in FIG. Figure 3 and Figure 4 The same parts as those in the structure example 1 of the heat insulating material shown in the figure are marked with the same reference numerals, and detailed description is omitted. Figure 12-13 The heat insulating material 80 shown is used instead Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0102] like Fig.12 and Fig.13 As shown, the heat insulating material 80 has a matrix 14 containing inorganic particles 4, inorganic fibers 15 dispersed in the matrix 14, and organic fibers 1. In addition, the organic fibers 1 and the inorganic fibers 15 are interwoven with each other to form a three-dimensional network structure. It should be noted that, in the present embodiment, an air layer 28 is formed around a portion of the inorganic fibers 15. In addition, the organic fiber 1 has a cladding portion 5 on a portion of the surface, and at least a portion of the inorganic fiber 15 is clad to the organic fiber 1 using the cladding portion 5. In addition, at least a portion of the inorganic particles 4 is clad to the organic fiber 1 using the cladding portion 5.

[0103] It should be noted that, in this specification, the inorganic fibers 15 are “dispersed”, which means that the inorganic fibers 15 are not extremely concentrated but are arranged throughout the entire body.

[0104] In the heat insulating material 80 thus constituted, the organic fibers 1 and the inorganic fibers 15 are interwoven to form a three-dimensional network structure, and this structure serves as a skeleton, so that high strength can be obtained. Therefore, even when the heat transfer suppression sheet 50 is compressed by the expansion of the battery cells 20a, 20b, and 20c during charge and discharge, the shape of the heat insulating material 80 can be maintained. As a result, the falling off (powder falling off) of the inorganic particles 4 can be suppressed, and the reduction of the heat insulating effect due to the compression deformation of the heat insulating material 80 can be prevented.

[0105] In addition, since the heat insulating material 80 includes the organic fiber 1 having high flexibility, the flexibility of the heat insulating material 80 can be improved, and the organic fiber 1 can be easily entangled with the inorganic fiber 15 to form a three-dimensional network structure, and the strength can also be improved. On the other hand, if the heat insulating material 80 does not include the inorganic fiber 15, for example, when the battery cell 20a undergoes thermal runaway and the heat transfer suppression sheet arranged adjacent to the battery cell 20a is exposed to high temperature, the organic fiber 1 decomposes and the shape of the heat transfer suppression sheet cannot be maintained. Therefore, by making the heat insulating material 80 contain the organic fiber 1 having high flexibility and the inorganic fiber 15 that does not decompose even at high temperatures, a heat transfer suppression sheet having both flexibility and strength in a good balance can be obtained.

[0106] In addition, in the present embodiment, an air layer 28 is provided around the inorganic fibers 15 dispersed in the matrix 14. The thermal conductivity of the inorganic fibers 15 is higher than that of the organic fibers 1, but as described above, by forming the air layer 28 around the inorganic fibers 15, heat transfer between the inorganic fibers 15 and the matrix 14 can be suppressed. It should be noted that the air layer 28 is formed in the manufacturing process of the heat insulating material 80, but the air layer 28 does not need to be formed in the entire area around the inorganic fibers 15. As long as the air layer 28 is formed on at least a portion of the outer peripheral surface of the inorganic fibers 15, the heat transfer suppression effect can be obtained.

[0107] If the inorganic fibers 15 are uniformly dispersed in the matrix 14 , the air layer 28 in the matrix 14 is also uniformly dispersed and arranged, so that the heat insulating material 80 can obtain high heat insulating properties without unevenness.

[0108] In addition, in the heat insulating material 80, the organic fiber 1 has a cladding portion 5 covering at least a portion of the surface. The cladding portion 5 is a portion where the surface of the organic fiber 1 is melted and then solidified again, and is formed during the manufacturing process of the heat insulating material 80. When at least a portion of the inorganic fiber 15 is clad to the organic fiber 1 by the cladding portion 5, the organic fiber 1 and the inorganic fiber 15 intertwined with each other are fixed, so that the heat insulating material 80 with a further higher strength can be obtained.

[0109] Similarly, in this embodiment, the inorganic particles 4 are also fixed to the organic fibers 1 by the cladding portion 5 on the outer peripheral surface of the organic fibers 1, thereby achieving a higher powder fall-off suppression effect. Therefore, even if a portion of the battery cells 20a, 20b, and 20c expands and applies compressive stress or impact to the heat transfer suppression sheet, excellent thermal insulation performance can be maintained.

[0110] In the present embodiment, as a mechanism for suppressing the inorganic particles 4 from falling off from the sheet surface, it is considered that the organic fibers 1 and the inorganic fibers 15 are fused by the fusion-bonded portion 5 to form a strong three-dimensional skeleton, which can maintain the shape of the heat insulating material 80 and suppress the deformation or compression of the heat transfer suppression sheet. In addition, it is considered that regardless of whether the mica sheet 51 is present on the surface of the heat insulating material 80, if the organic fibers 1 and the inorganic fibers 15 are exposed on the surface of the heat insulating material 80, the impact applied to the heat insulating material 80 can be absorbed and the inorganic particles 4 can be maintained.

[0111] It should be noted that in the heat insulating material 80, the cladding portion 5 does not necessarily have to completely cover the outer peripheral surface of the organic fiber 1, and there may be a partial area where the cladding portion 5 does not exist. Even in such a case, the effect of retaining the inorganic particles 4 can be fully obtained.

[0112] <Heat insulation material (Structural example 6)>

[0113] Fig.14 1 is a photograph in lieu of a drawing showing a structural example 6 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Fig.15 It is shown Fig.14 Other areas of the insulation material are shown in the accompanying drawings in lieu of photographs. Fig.16 It is shown Fig.14 and Fig.15 The following is a substitute photograph of a cross section of the insulation material shown. Figure 14 to Figure 16 In the structural example 6 shown in FIG. Figures 9 to 11 The same parts of the structure example 4 of the heat insulating material shown in the figure are marked with the same reference numerals, and detailed description is omitted. Figure 14 to Figure 16 The heat insulating material 90 shown is used instead Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0114] like Fig.14 As shown, the heat insulating material 90 has inorganic particles 4 and organic fibers 1. In addition, at least a portion of the organic fibers 1 has a branch structure consisting of a base 32 and branches 33 extending from the base 32. In this embodiment, the branches 33 extend from the base 32 in four directions: direction D1, direction D2, direction D3, and direction D4. In addition, the base 32 and the plurality of branches 33 form a skeleton.

[0115] In addition, Fig.15 The other regions of the heat insulating material 90 shown include organic fibers 1 having a branched structure consisting of a base 32 and branches 33 extending from the base 32. Fig.15 The organic fiber 1 shown includes a base portion 32 and branch portions 33 extending from the base portion 32 in five directions: direction D1 , direction D2 , direction D3 , direction D4 , and direction D5 . The base portion 32 is thicker than the plurality of branch portions 33 .

[0116] In addition, if Fig.14 and Fig.15 As shown, in the present embodiment, the inorganic particles 4 are fused onto the surface of the organic fiber 1 , and thus the surface of the organic fiber 1 is covered with the inorganic particles 4 .

[0117] In addition, if Fig.16 As shown in the cross-sectional view of FIG. 1 , a plurality of pores 7 are formed in the heat insulating material 90. In addition, in the heat insulating material 90, at least a portion of the plurality of organic fibers 1 are melt-coated to form a fiber bundle 6, and gaps 8 are formed between the plurality of organic fibers 1 constituting the fiber bundle 6. Fig.16 It can also be confirmed that the organic fiber 1 has a branched structure consisting of a base portion 32 and branches 33 extending from the base portion 32 in three directions.

[0118] In addition, a fiber layer 11 is formed on at least a portion of the first surface and the second surface orthogonal to the thickness direction of the insulating material 90. The fiber layer 11 is formed by mutually cladding at least a portion of a plurality of organic fibers 1 and forming them in layers on the surface (the first surface and the second surface) of the insulating material 90. In addition, a composite layer 12 is formed between the fiber layer 11 and a base layer 13 including inorganic particles 4 and organic fibers 1. The composite layer 12 is a layer in which a portion of the fiber layer 11 and a portion of the inorganic particles 4 are mixed. Specifically, the composite layer 12 is a region including a plurality of organic fibers 1 clad to each other and inorganic particles 4 clad to the organic fibers 1.

[0119] It should be noted that the fiber bundle 6 is formed by interweaving more than ten organic fibers 1, partially fusion-coating the organic fibers 1, and is arranged in an arbitrary direction inside the heat insulating material 90. On the other hand, the fiber layer 11 is a layer formed by assembling more than ten organic fibers 1 on the surface of the heat insulating material 90, and extends in a direction substantially parallel to the surface, for example, in a stripe shape.

[0120] In the heat insulating material 90 configured as above, at least a part of the organic fibers 1 has a branched structure composed of the base 32 and the branch 33, so that the organic fibers 1 serve as a skeleton and can maintain the shape of the heat insulating material 90. In the present embodiment, the base 32 is composed of a fusion portion where the organic fibers 1 are fused to each other. Specifically, the base 32 is a portion where a part of a plurality of organic fibers 1 contact and fuse with each other and then solidify, and therefore is thicker than the branch 33. Therefore, the entire skeleton can be firmly supported by the base 32, and thus the strength of the heat insulating material 90 can be significantly improved.

[0121] In the heat insulating material 90, at least a portion of the organic fiber 1 has a branching structure consisting of a base 32 and branches 33 extending from the base 32 in at least three directions. The branching structure can also be confirmed in a cross-sectional photograph of the heat insulating material 90, and as a method for more simply confirming the branching structure, a method of observing a cross section obtained by tearing the heat insulating material 90 along a plane direction perpendicular to its thickness direction can be cited. In this way, by observing the cross section, the organic fiber 1 having a branching structure consisting of a base 32 and branches 33 extending from the base 32 in at least three directions can be easily confirmed. The base 32 and the branches 33 are described in more detail below.

[0122] (Base (weld portion))

[0123] Regarding the welded portion, when a core-sheath structure binder fiber is used as the material of the heat insulating material 90, the sheath portion of the binder fiber is temporarily melted by heating at a portion where a plurality of binder fibers are in contact with each other, and then cooled, thereby forming the welded portion. When a core-sheath structure binder fiber is used as the material of the heat insulating material 90, the welded portion includes a second organic material constituting the sheath portion.

[0124] Thus, in the manufacturing process of the heat transfer suppressing sheet 50, when the sheaths of the contact regions of the plurality of binder fibers are melted by heating, the amount of the melted sheath (second organic material) increases compared to the case where the sheath of one binder fiber is melted, and a thick welded portion (base 32) is formed after cooling. As a result, the frame is firmly supported by the base 32.

[0125] (Branch)

[0126] The branch portions 33 extend from the base portion 32 in at least three directions and have the effect of holding the inorganic particles 4. In addition, since the base portion 32 and the branch portions 33 form a skeleton, the strength of the heat transfer suppressing sheet 50 can be improved. This can achieve a high powder fall-off suppressing effect.

[0127] When a core-sheath structured binder fiber is used as the organic fiber 1 , the branch portion 33 is a part of the core-sheath structured binder fiber and has a core portion made of a first organic material and a sheath portion made of a second organic material.

[0128] As long as the branches 33 extending from the base 32 extend in at least three directions, they can form a skeleton composed of the organic fiber 1. In addition, the plurality of branches 33 preferably extend in different three-dimensional directions, thereby forming a strong three-dimensional skeleton.

[0129] In the above-mentioned insulating material 90, a plurality of branches 33 extend from the base 32, so that the inorganic particles 4 can be held by these plurality of branches 33, and a high powder falling-off suppression effect can be obtained by a synergistic effect with the sheet strength improvement effect based on the skeleton formation. Therefore, for example, during the charge and discharge of the battery cells 20a, 20b, and 20c, even if a part of them expands and applies compressive stress or impact to the heat transfer suppression sheet, the shape of the insulating material 90 can be maintained. As a result, the falling off (powder falling off) of the inorganic particles 4 can be suppressed, and the reduction of the insulation effect due to the compression deformation of the insulating material 90 can be prevented.

[0130] As a mechanism capable of suppressing the inorganic particles 4 from falling off from the surface of the heat insulating material 90, it is considered that, in addition to the same effect as the heat insulating material 60 of the above-mentioned structural example 3, there is also the inorganic particles 4 holding effect based on the branch 33. In addition, if the inorganic particles 4 are fused to the surface of the organic fiber 1, the organic fiber 1 has an apparently thick fiber diameter, and therefore the strength is higher than the strength of the organic fiber 1 alone, and a high holding effect of the inorganic particles 4 can be obtained.

[0131] In addition, the heat insulating material 90 may have a region where the inorganic particles 4 are not partially melt-coated on the outer peripheral surface of the organic fiber 1. Even in such a case, the effect of holding the inorganic particles 4 can be fully obtained.

[0132] Furthermore, since the heat insulating material 90 includes the highly flexible organic fibers 1 , the flexibility of the heat insulating material 90 can be improved, and the organic fibers 1 are easily entangled with each other, thereby achieving an effect of improving the sheet strength.

[0133] Furthermore, since the heat insulating material 90 has a plurality of pores 7 and has gaps 8 between the plurality of organic fibers 1 constituting the fiber bundle 6, the heat insulating performance can be improved by the air heat insulating effect. In addition, due to the presence of the gaps 8, the organic fibers 1 are not completely restrained, so the flexibility and strength of the heat insulating material 90 can be further improved. The gaps 8 do not need to be formed in the entire region between the plurality of organic fibers 1, and as long as the gaps 8 are formed in at least a portion between the organic fibers 1, the heat transfer suppression effect can be obtained.

[0134] Furthermore, since the heat insulating material 90 includes the fiber bundle 6 and the fiber layer 11, a higher sheet strength can be obtained compared to the case where the organic fibers 1 are dispersedly arranged. In addition, since the fiber layer 11 is not simply arranged on the base layer 13, but a composite layer 12 in which a part of the fiber layer 11 and a part of the inorganic particles 4 are mixed exists between the fiber layer 11 and the base layer 13, the fiber layer 11 is surely constrained on the surface of the heat insulating material 90. Therefore, the strength of the heat insulating material 90 can be improved.

[0135] <Heat insulation material (Structural example 7)>

[0136] Fig.17 1 is a photograph in lieu of a drawing showing a structural example 7 of a heat insulating material used in a heat transfer suppressing sheet according to an embodiment of the present invention. Fig.18A It is enlarged to show Fig.17 A photograph of a portion of the insulation material shown in the accompanying drawings, Fig.18B It is a schematic representation Fig.18A The drawings shown are diagrams in lieu of photographs. Fig.17 , Fig.18A and Fig.18B In the structural example 7 shown in FIG. Figure 5 The same parts as those in the structure example 2 of the heat insulating material shown in the figure are marked with the same reference numerals, and detailed description is omitted. Fig.17 , Fig.18A and Fig.18B The heat insulating material 110 shown is used instead of Figure 1 The heat insulating material 10 of the heat transfer suppressing sheet 50 is shown.

[0137] like Fig.17 , Fig.18A and Fig.18B As shown, the heat insulating material 110 has inorganic particles 4 and organic fibers 1. A first region 42 having a striped fiber bundle 47 composed of a plurality of organic fibers 1 and a second region 43 where no fiber bundle 47 exists are formed on the surface of the heat insulating material 110. In this specification, the fiber bundle 47 is formed by interweaving 10 or more organic fibers 1, and extends in a striped shape in a substantially parallel direction on the surface of the heat insulating material 110.

[0138] That is, when observing the surface of the heat insulating material 110, Fig.18A and Fig.18B As shown, a plurality of organic fibers 1 are observed to be intertwined in the first region 42. On the other hand, in the second region 43, although there are also locations where a plurality of organic fibers 1 are observed, a fiber bundle 47 in which a plurality of organic fibers 1 are intertwined is not observed.

[0139] It should be noted that in the present embodiment, the first region 42 and the second region 43 form an island structure, and the second region 43 corresponding to the island portion is formed so as to be surrounded by the first region 42 corresponding to the sea portion.

[0140] In the heat insulating material 110, the fiber bundle 47 formed by interweaving the organic fibers 1 is present in a stripe-like manner extending on the surface of the heat insulating material 110, thereby being able to improve the strength of the heat insulating material 110. In addition, since the entire surface is not covered by the fiber bundle 47, but there is a first area 42 where the fiber bundle 47 exists, and a second area where the fiber bundle 47 does not exist, the heat insulating material 110 is also excellent in softness. In addition, since the fiber bundle 47 is present on the surface of the heat insulating material 110, even when the heat insulating material 110 is subjected to impact and pressure, the fiber bundle 47 can absorb and mitigate the impact and compression force. Therefore, the falling off (powder falling off) of the inorganic particles 4 can be suppressed, and the reduction of the heat insulating performance of the heat insulating material 110 can be prevented.

[0141] It should be noted that in the heat insulating material 110, the fiber bundles 47 formed by interweaving the organic fibers 1 and the organic fibers 1 are present not only on the surface of the heat insulating material 110 but also inside the heat insulating material 110. This can provide even better strength.

[0142] The length of the fiber bundle 47 formed so as to extend on the surface of the heat insulating material 110 is preferably long to a certain extent. Fig.19 An example of a method of defining the length of the fiber bundle 47 will be described.

[0143] like Fig.19 As shown in FIG. 1 , a rectangular imaginary frame 21 is arranged along the fiber bundle 47 extending in a stripe shape on the surface of the heat insulating material 110. In this embodiment, the imaginary frame 21 has a size of 5 mm square, and is arranged so that the imaginary frames 21 are continuous with each other. At this time, if there are fiber bundles 47 penetrating at least three continuous imaginary frames 21, it can be judged that the effect of improving the strength of the heat insulating material 110 is sufficient.

[0144] Alternatively, the length of the fiber bundle 47 extending in a stripe shape may be simply measured. For example, a method may be used in which a rope or the like is arranged on the surface of the heat insulating material 110 along the fiber bundle 47 and then the length of the rope is measured. When the length of the continuous fiber bundle 47 is measured, if there is a fiber bundle 47 having a length of 20 mm or more, the effect of improving the strength of the heat insulating material 110 can be sufficiently obtained.

[0145] In addition, if Fig. 20 As shown, if the fiber bundles 47 on the surface of the heat insulating material 110 are connected in a mesh shape, the sheet strength can be further improved.

[0146] The above describes the structure examples 1 to 7 of the heat insulating material, but the structure of the heat insulating material is not limited thereto, and heat insulating materials having various structures can be used. Specifically, the heat insulating materials of the above structure examples 1 to 7 have excellent heat insulating effects, and have various characteristics such as the effect of suppressing powder shedding, the effect of further improving strength, and the effect of maintaining shape. Therefore, Figure 1 As shown, by laminating the mica sheet 51 on the above-mentioned heat insulating material, a heat transfer suppressing sheet having further excellent impact resistance can be obtained.

[0147] The materials constituting the heat transfer suppression sheet 50 of the present embodiment will be described below. First, the materials constituting the heat insulating material will be described.

[0148] <Organic Fiber>

[0149] The organic fiber 1 imparts flexibility to the thermal insulation material, and the inorganic particles 4 and other organic fibers 1 are melt-coated on its surface, thereby having the effect of maintaining the strength and shape of the sheet. As the material of the organic fiber 1 in the thermal insulation material, a single-component organic fiber can also be used, but it is preferred to use an adhesive fiber with a core-sheath structure. The adhesive fiber with a core-sheath structure has a core extending in the longitudinal direction of the fiber, and a sheath formed in a manner covering the outer peripheral surface of the core. In addition, the core is composed of a first organic material, and the sheath is composed of a second organic material, and the melting point of the first organic material is higher than that of the second organic material. In the case of using an adhesive fiber with a core-sheath structure as a material, the core portion in the above-mentioned thermal insulation material is equivalent to the organic fiber 1. In addition, when the thermal insulation material is manufactured, the second organic material constituting the sheath is melted and then solidified again, so in the thermal insulation material, the sheath becomes a melt-coated portion 5.

[0150] When a core-sheath structured binder fiber is used as the material of the organic fiber 1, there is no particular limitation as long as the core portion, i.e., the first organic material constituting the organic fiber 1, has a higher melting point than the sheath portion, i.e., the second organic material, present on the outer peripheral surface of the organic fiber 1. The first organic material may be at least one selected from polyethylene terephthalate, polypropylene, and nylon.

[0151] (Organic fiber content)

[0152] In the present embodiment, if the content of the organic fiber 1 in the heat insulating material is appropriately controlled, a sufficient reinforcement effect of the skeleton can be obtained.

[0153] The content of the organic fiber 1 is preferably 2% by mass or more, more preferably 4% by mass or more, relative to the total mass of the thermal insulation material. In addition, if the content of the organic fiber 1 is too much, the content of the inorganic particles 4 is relatively reduced. Therefore, in order to obtain the desired thermal insulation performance, the content of the organic fiber is preferably 10% by mass or less, more preferably 8% by mass or less, relative to the total mass of the thermal insulation material.

[0154] (Fiber length of organic fibers)

[0155] The fiber length of the organic fibers 1 is not particularly limited, but the average fiber length of the organic fibers is preferably 10 mm or less from the viewpoint of ensuring moldability and processability.

[0156] On the other hand, from the viewpoint of allowing the organic fibers 1 to function as a skeleton and ensuring the compressive strength of the heat insulating material, the average fiber length of the organic fibers 1 is preferably 0.5 mm or more.

[0157] <Cladding section>

[0158] The cladding portion 5 is formed by temporarily melting the surface of the organic fiber 1 or the sheath of the binder fiber having a core-sheath structure by heating and then cooling it. In some cases, the inorganic particles 4 are clad on the surface of the organic fiber 1, and the organic fibers 1 are clad with each other. When a binder fiber having a core-sheath structure is used as the material of the organic fiber 1, the cladding portion 5 includes a second organic material constituting the sheath.

[0159] (Second organic material)

[0160] The second organic material is not particularly limited as long as it has a lower melting point than the first organic material constituting the organic fiber 1. The second organic material may be at least one selected from polyethylene terephthalate, polyethylene, polypropylene, and nylon.

[0161] The melting point of the second organic material is preferably 90° C. or higher, more preferably 100° C. or higher. The melting point of the second organic material is preferably 150° C. or lower, more preferably 130° C. or lower.

[0162] <Inorganic particles>

[0163] As inorganic particles, single inorganic particles can be used, and more than two kinds of inorganic particles can also be used. As the kind of inorganic particles, from the aspect of heat transfer inhibition effect, preferably use the particles consisting of at least one inorganic material selected from oxide particles, carbide particles, nitride particles and inorganic hydrate particles, more preferably use oxide particles. In addition, there is no particular limitation on shape, preferably comprising at least one selected from nanoparticles, hollow particles and porous particles, specifically, inorganic hollow balls such as silicon dioxide nanoparticles, metal oxide particles, microporous particles, hollow silicon dioxide particles, particles consisting of thermally expansive inorganic materials, particles consisting of water-containing porous bodies, etc. can also be used.

[0164] If the average secondary particle size of the inorganic particles is 0.01 μm or more, it is easy to obtain and the increase in manufacturing cost can be suppressed. In addition, if it is 200 μm or less, the desired insulation effect can be obtained. Therefore, the average secondary particle size of the inorganic particles is preferably 0.01 μm or more and 200 μm or less, and more preferably 0.05 μm or more and 100 μm or less.

[0165] It should be noted that, if two or more inorganic particles with different heat transfer inhibition effects are used together, the exothermic body can be cooled in multiple stages, and endothermic effect can be shown in a larger temperature range. Specifically, it is preferred that large-diameter particles and small-diameter particles are mixed and used. For example, when nanoparticles are used as inorganic particles on one side, inorganic particles as the other side preferably include inorganic particles consisting of metal oxides. Hereinafter, the inorganic particles with small diameter are used as the first inorganic particles and the inorganic particles with large diameter are used as the second inorganic particles, and the inorganic particles are further described in detail.

[0166] <First Inorganic Particles>

[0167] (Oxide particles)

[0168] Oxide particles have a high refractive index and a strong effect of diffuse reflection of light. Therefore, when oxide particles are used as the first inorganic particles, radiative heat transfer can be suppressed, especially in high temperature areas such as abnormal heat release. As oxide particles, at least one particle selected from silica, titania, zirconium oxide, zircon, barium titanate, zinc oxide and aluminum oxide can be used. That is, among the above-mentioned oxide particles that can be used as inorganic particles, only one kind can be used, or two or more kinds of oxide particles can be used. In particular, silica is a component with high thermal insulation properties, and titania is a component with a higher refractive index than other metal oxides. It has a high effect of diffuse reflection of light and shielding radiant heat in high temperature areas above 500°C, so it is most preferred to use silica and titania as oxide particles.

[0169] (Average primary particle size of oxide particles: 0.001 μm or more and 50 μm or less)

[0170] The particle size of the oxide particles may affect the effect of reflecting radiant heat. Therefore, if the average primary particle size is limited to a predetermined range, a higher thermal insulation property can be obtained.

[0171] That is, if the average primary particle size of the oxide particles is 0.001 μm or more, it is sufficiently larger than the wavelength of light that contributes to heating, so that the light is efficiently diffusely reflected. Therefore, in the high temperature range above 500°C, the radiation heat transfer in the insulation material is suppressed, and the insulation performance can be further improved.

[0172] On the other hand, if the average primary particle size of the oxide particles is less than 50 μm, the number of contacts between the particles will not increase even if compressed, making it difficult to form a path for conductive heat transfer. This can particularly reduce the impact on the insulation in the normal temperature range where conductive heat transfer dominates.

[0173] It should be noted that in the present invention, the average primary particle size can be obtained by observing the particles using a microscope, comparing with a standard scale, and taking the average of any 10 particles.

[0174] (Nanoparticles)

[0175] In the present invention, nanoparticles refer to nano-scale particles with an average primary particle size of less than 1 μm in a spherical or nearly spherical shape. Since nanoparticles have a low density, conductive heat transfer can be suppressed. If nanoparticles are used as the first inorganic particles, the three-dimensionally connected pores 7 are further miniaturized, and excellent thermal insulation that suppresses convective heat transfer can be obtained. Therefore, when the battery is used in a normal temperature range, heat conduction between adjacent nanoparticles can be suppressed. From this aspect, nanoparticles are preferably used.

[0176] In addition, when nanoparticles with a small average primary particle size are used as oxide particles, even when the insulation material is compressed due to expansion associated with thermal runaway of the battery cell and the internal density increases, the increase in conductive heat transfer of the insulation material can be suppressed. It is believed that the reason is that nanoparticles easily form fine gaps between particles due to electrostatic repulsion, and the packing density is low, so the particles are filled in a manner having buffering properties.

[0177] It should be noted that in the present invention, when nanoparticles are used as the first inorganic particles, there is no particular limitation on the material as long as it meets the above definition of nanoparticles. For example, silicon dioxide nanoparticles are highly thermally insulating materials, and the contact points between the particles are small, so the heat conducted by the silicon dioxide nanoparticles is less than that when using silicon dioxide particles with a large particle size. In addition, the bulk density of the silicon dioxide nanoparticles usually obtained is 0.1 (g / cm 3 ), so for example, even if the battery cells arranged on both sides of the insulation material undergo thermal expansion and a large compressive stress is applied to the insulation material, the size (area) and number of the contact points between the silica nanoparticles will not increase significantly, and the insulation can be maintained. Therefore, as nanoparticles, silica nanoparticles are preferably used. As silica nanoparticles, wet silica, dry silica, and aerogel can be cited. The silica nanoparticles that are particularly suitable for this embodiment are described below.

[0178] Generally, wet silica particles aggregate, whereas dry silica particles can be dispersed. In the temperature range below 300°C, heat conduction is dominant, so dry silica particles that can be dispersed can achieve superior thermal insulation performance compared to wet silica.

[0179] It should be noted that the thermal insulation material of this embodiment is preferably produced by a dry process in which a mixture containing materials is processed into a sheet shape. Therefore, as inorganic particles, dry silica, silica aerogel, etc. having low thermal conductivity are preferably used.

[0180] (Average primary particle size of nanoparticles: 1 nm or more and 100 nm or less)

[0181] When the average primary particle size of the nanoparticles is limited to a predetermined range, further higher thermal insulation properties can be obtained.

[0182] That is, when the average primary particle size of the nanoparticles is set to be between 1 nm and 100 nm, especially in a temperature range of less than 500° C., the convection heat transfer and conduction heat transfer of the heat in the thermal insulation material can be suppressed, and the thermal insulation can be further improved. In addition, even when compressive stress is applied, the gaps remaining between the nanoparticles and the contacts between the multiple particles can suppress the conduction heat transfer, and the thermal insulation of the thermal insulation material can be maintained.

[0183] It should be noted that the average primary particle size of the nanoparticles is more preferably 2 nm or more, and further preferably 3 nm or more. On the other hand, the average primary particle size of the nanoparticles is more preferably 50 nm or less, and further preferably 10 nm or less.

[0184] (Inorganic hydrate particles)

[0185] When the inorganic hydrate particles are exposed to heat from the exothermic body and reach a temperature above the thermal decomposition start temperature, they undergo thermal decomposition, releasing their own crystal water to lower the temperature of the exothermic body and its surroundings, demonstrating a so-called "endothermic effect." In addition, after releasing the crystal water, they become porous and exhibit a heat-insulating effect through countless air pores.

[0186] Specific examples of inorganic hydrates include aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), calcium hydroxide (Ca(OH)2), zinc hydroxide (Zn(OH)2), iron hydroxide (Fe(OH)2), manganese hydroxide (Mn(OH)2), zirconium hydroxide (Zr(OH)2), gallium hydroxide (Ga(OH)3), etc.

[0187] For example, aluminum hydroxide has about 35% of crystal water, and as shown in the following formula, it undergoes thermal decomposition to release crystal water, exhibiting an endothermic effect. Moreover, after releasing the crystal water, it becomes a porous aluminum oxide (Al2O3), which functions as a heat insulator.

[0188] 2Al(OH)3→Al2O3+3H2O

[0189] It should be noted that the heat transfer suppression sheet 50 of the present embodiment is suitable for being sandwiched between battery cells, for example, but in a battery cell that has thermal runaway, the temperature rises sharply to more than 200° C., and the temperature continues to rise to around 700° C. Therefore, the inorganic particles are preferably composed of an inorganic hydrate having a thermal decomposition starting temperature of 200° C. or more.

[0190] Regarding the thermal decomposition starting temperatures of the inorganic hydrates listed above, aluminum hydroxide is about 200°C, magnesium hydroxide is about 330°C, calcium hydroxide is about 580°C, zinc hydroxide is about 200°C, iron hydroxide is about 350°C, manganese hydroxide is about 300°C, zirconium hydroxide is about 300°C, and gallium hydroxide is about 300°C. They all roughly overlap with the temperature range of the rapid temperature rise of the battery cell when thermal runaway occurs, and can effectively suppress the temperature rise. Therefore, they can be said to be preferred inorganic hydrates.

[0191] (Average secondary particle size of inorganic hydrate particles: 0.01 μm or more and 200 μm or less)

[0192] In addition, when inorganic hydrate particles are used as the first inorganic particles, if the average particle size is too large, the first inorganic particles (inorganic hydrate) located near the center of the thermal insulation material need a certain amount of time before reaching their thermal decomposition temperature, so the first inorganic particles near the center of the sheet may not be completely thermally decomposed. Therefore, the average secondary particle size of the inorganic hydrate particles is preferably 0.01 μm to 200 μm, and more preferably 0.05 μm to 100 μm.

[0193] (Particles composed of heat-expandable inorganic material)

[0194] Examples of the thermally expandable inorganic material include vermiculite, bentonite, mica, and perlite.

[0195] (Particles composed of a porous body containing water)

[0196] Specific examples of the hydrous porous body include zeolite, kaolinite, montmorillonite, acid clay, diatomaceous earth, wet silica, dry silica, aerogel, mica, vermiculite and the like.

[0197] (Inorganic hollow sphere)

[0198] The heat insulating material used in the present invention may contain inorganic hollow spheres as the first inorganic particles.

[0199] When the inorganic hollow spheres are included, convection heat transfer or conductive heat transfer of heat in the thermal insulation material can be suppressed in a temperature range lower than 500° C., and the thermal insulation property of the thermal insulation material can be further improved.

[0200] As the inorganic hollow sphere, at least one selected from the group consisting of volcanic ash hollow spheres, silica hollow spheres, fly ash hollow spheres, barite hollow spheres, and glass hollow spheres can be used.

[0201] (Content of inorganic hollow spheres: 60% by mass or less relative to the total mass of the thermal insulation material)

[0202] The content of the inorganic hollow spheres is preferably 60% by mass or less based on the total mass of the thermal insulation material.

[0203] (Average particle size of inorganic hollow spheres: 1 μm or more and 100 μm or less)

[0204] The average particle size of the inorganic hollow spheres is preferably 1 μm or more and 100 μm or less.

[0205] <Second Inorganic Particles>

[0206] In the case of containing 2 kinds of inorganic particles in the thermal insulation material, the second inorganic particle is not particularly limited as long as material, particle diameter etc. are different from the first inorganic particle. As the second inorganic particle, inorganic hollow balls such as oxide particles, carbide particles, nitride particles, inorganic hydrate particles, silicon dioxide nanoparticles, metal oxide particles, microporous particles or hollow silicon dioxide particles, particles made of thermal expansion inorganic materials, particles made of water-containing porous bodies etc. can be used, and their details are as described above.

[0207] It should be noted that the conduction heat transfer of nanoparticles is extremely small, and even when compressive stress is applied to the thermal insulation material, excellent thermal insulation can be maintained. In addition, metal oxide particles such as titanium dioxide have a high effect of shielding radiant heat. And then, if inorganic particles with large diameter and inorganic particles with small diameter are used, the inorganic particles with small diameter can enter the gap between the inorganic particles with large diameter, thus becoming a more dense structure, and the heat transfer inhibition effect can be improved. Therefore, when using, for example, nanoparticles as the above-mentioned first inorganic particles, it is preferred that the thermal insulation material further contains particles consisting of metal oxides whose particle diameter is larger than the first inorganic particles as the second inorganic particles.

[0208] Examples of the metal oxide include silicon oxide, titanium oxide, aluminum oxide, barium titanate, zinc oxide, zircon, zirconium oxide, etc. Titanium oxide (titanium dioxide) is a component with a higher refractive index than other metal oxides, and has a high effect of diffusely reflecting light and shielding radiant heat in a high temperature range of 500° C. or more, so titanium dioxide is most preferably used.

[0209] When at least one particle selected from dry silica particles and silica aerogel is used as the first inorganic particle and at least one particle selected from titanium dioxide, zircon, zirconium oxide, silicon carbide, zinc oxide and aluminum oxide is used as the second inorganic particle, in order to obtain excellent thermal insulation performance in a temperature range of 300° C. or less, the first inorganic particle is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more relative to the total mass of the inorganic particles. In addition, the first inorganic particle is preferably 95% by mass or less, more preferably 90% by mass or less, and further preferably 80% by mass or less relative to the total mass of the inorganic particles.

[0210] On the other hand, in order to obtain excellent thermal insulation performance in a temperature range exceeding 300° C., the second inorganic particles are preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more relative to the total mass of the inorganic particles. In addition, the second inorganic particles are preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less relative to the total mass of the inorganic particles.

[0211] (Average primary particle size of the second inorganic particles)

[0212] When the thermal insulation material contains the second inorganic particles composed of metal oxide, if the average primary particle size of the second inorganic particles is 1 μm to 50 μm, radiant heat transfer can be effectively suppressed in a high temperature region of 500° C. or higher. The average primary particle size of the second inorganic particles is more preferably 5 μm to 30 μm, and more preferably 10 μm or less.

[0213] (Content of Inorganic Particles)

[0214] In the present embodiment, if the total content of the inorganic particles 4 in the heat insulating material is appropriately controlled, the heat insulating property of the heat insulating material can be sufficiently ensured.

[0215] The total content of the inorganic particles 4 is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total mass of the thermal insulation material. In addition, if the total content of the inorganic particles 4 is too much, the content of the organic fiber is relatively reduced. Therefore, in order to fully obtain the reinforcing effect of the skeleton and the retention effect of the inorganic particles, the total content of the inorganic particles 4 is preferably 95% by mass or less, more preferably 90% by mass or less, relative to the total mass of the thermal insulation material.

[0216] The content of the inorganic particles 4 in the heat insulating material can be calculated by, for example, heating the heat insulating material at 800° C. to decompose the organic components and then measuring the mass of the remainder.

[0217] <Inorganic Fiber>

[0218] As the inorganic fiber 15, a single inorganic fiber may be used, or two or more inorganic fibers may be used in combination. Examples of the inorganic fiber include silica fiber, alumina fiber, aluminum silicate fiber, zirconium oxide fiber, carbon fiber, soluble fiber, refractory ceramic fiber, aerogel composite material, magnesium silicate fiber, alkaline earth silicate fiber, potassium titanate fiber, silicon carbide fiber, potassium titanate whisker fiber and other ceramic fibers, glass fiber, glass wool, mineral wool and other glass fibers, and natural mineral fibers other than these fibers such as rock wool, basalt fiber, wollastonite, mullite fiber and the like.

[0219] These inorganic fibers are preferred from the perspectives of heat resistance, strength, availability, etc. Among the inorganic fibers, at least one selected from silica-alumina fibers, alumina fibers, silica fibers, rock wool, alkaline earth silicate fibers, and glass fibers is particularly preferred from the perspective of handleability.

[0220] The cross-sectional shape of the inorganic fiber is not particularly limited, and examples thereof include circular cross-section, flat cross-section, hollow cross-section, polygonal cross-section, core cross-section, etc. Among them, fibers with a hollow cross-section, flat cross-section or polygonal cross-section with a special cross-section can be appropriately used because they can slightly improve thermal insulation properties.

[0221] The preferred lower limit of the average fiber length of the inorganic fibers is 0.1 mm, and the more preferred lower limit is 0.5 mm. On the other hand, the preferred upper limit of the average fiber length of the inorganic fibers is 50 mm, and the more preferred upper limit is 10 mm. If the average fiber length of the inorganic fibers is less than 0.1 mm, it is not easy to cause the inorganic fibers to be entangled with each other, and the mechanical strength of the thermal insulation material may be reduced. On the other hand, if the average fiber length exceeds 50 mm, although the reinforcing effect can be obtained, the inorganic fibers cannot be tightly entangled with each other, or only a single inorganic fiber is rolled up, and thus continuous gaps are easily generated, which may cause a reduction in thermal insulation.

[0222] The preferred lower limit of the average fiber diameter of the inorganic fiber is 1 μm, the more preferred lower limit is 2 μm, and the further preferred lower limit is 3 μm. On the other hand, the preferred upper limit of the average fiber diameter of the inorganic fiber is 15 μm, and the more preferred upper limit is 10 μm. If the average fiber diameter of the inorganic fiber is less than 1 μm, the mechanical strength of the inorganic fiber itself may be reduced. In addition, from the perspective of the impact on human health, the average fiber diameter of the inorganic fiber is preferably greater than 3 μm. On the other hand, if the average fiber diameter of the inorganic fiber is greater than 15 μm, the solid heat transfer using the inorganic fiber as the medium increases, which may lead to a decrease in thermal insulation, and the formability and strength of the thermal insulation material may deteriorate.

[0223] (Inorganic fiber content)

[0224] In the present embodiment, when the heat insulating material contains inorganic fibers, the content of the inorganic fibers is preferably 3% by mass or more and 15% by mass or less relative to the total mass of the heat insulating material.

[0225] In addition, the content of the inorganic fiber is more preferably 5% by mass or more and 10% by mass or less relative to the total mass of the thermal insulation material. By setting such a content, the shape retention, extrusion resistance, wind pressure resistance, and inorganic particle retention capacity based on the inorganic fiber can be well balanced. In addition, by appropriately controlling the content of the inorganic fiber, the organic fiber 1 and the inorganic fiber are entangled with each other to form a three-dimensional network, so that the effect of retaining the inorganic particles 4 and other mixed materials described later can be further improved.

[0226] <Other mixed materials>

[0227] It should be noted that the thermal insulation material of this embodiment may further contain a binder, a colorant, etc. as needed. These are useful for the purpose of reinforcing the thermal insulation material, improving the formability, etc., and the total amount is preferably 10% by mass or less relative to the total mass of the thermal insulation material.

[0228] <Mica Sheet>

[0229] The mica sheet 51 is formed by processing a mica sheet material containing mica into a sheet shape. As a mica sheet material, it is preferred that it also contains oxide particles, oxide fibers, etc. in addition to mica. Specifically, SiO2, Al2O3, Ti2O3, etc. can be cited, but the utility model is not limited to these materials. It should be noted that it is more preferred to use a mica sheet composed of natural minerals. The sheet shape can generally be a flat sheet without holes, or it can have holes. However, it is also possible to use a shape in which holes are provided in at least a part of the center part or other areas of the mica sheet so that when the battery cell expands and contracts, the mica sheet can follow the battery cell without cracking.

[0230] [Method for producing heat transfer suppressing sheet]

[0231] Hereinafter, a method for producing the heat transfer suppression sheet according to the present embodiment, particularly an example using the heat insulating material of Configuration Example 2, will be described in detail.

[0232] For example, a binder fiber (not shown) having a core-sheath structure, the inorganic particles 4, and the inorganic fibers 15 are put into a mixer such as a V-type mixer at a predetermined ratio to prepare a mixture.

[0233] As described above, the binder fiber preferably has a core-sheath structure in which the core is made of a first organic material and the sheath is made of a second organic material. In this case, the melting point of the first organic material is higher than that of the second organic material.

[0234] Thereafter, the obtained mixture is put into a predetermined mold, and pressurized by a press machine or the like, and the obtained molded body is heated, whereby the sheath of the binder fiber is melted. Thereafter, by cooling the heated molded body, the melted second organic material constituting the sheath and the inorganic particles 4 existing around the binder fiber are fused to the core (organic fiber 1), and also fused to each other in the region where the binder fibers are in contact with each other. Thus, a heat insulating material 40 processed into a sheet shape can be obtained.

[0235] Thereafter, the heat insulating material 40 is disposed between the pair of mica sheets 51 prepared in advance, and the two are fixed. There is no particular limitation on the method for fixing the heat insulating material 40 and the mica sheets 51 to each other, and various methods can be used, such as a method of bonding with an adhesive or the like, a method of sewing with a thread or the like, a method of clamping and fixing with a fixing jig, a method of covering with a film or the like, and a method of fixing with a heat compressible film and then heating to shrink the film.

[0236] It should be noted that the thermal insulation material 10 not including the inorganic fibers 15 and the thermal insulation material not including the organic fibers 1 can be obtained by the same manufacturing method as the thermal insulation material 40 , and the use of the organic fibers 1 and the inorganic fibers 15 can be arbitrarily selected.

[0237] It should be noted that when the materials of the above-mentioned heat insulating material are mixed and heated while being pressurized, the interwoven organic fibers 1 exposed on the surface are heated and form the surface of the heat insulating material 40 in the form of a fiber layer 11. The fiber layer 11 obtained in this way can improve the strength of the heat insulating material 40 and has the effect of relieving the impact on the surface of the heat insulating material 40.

[0238] The above-mentioned heat insulating material is preferably manufactured by a dry method. When the dry method is used, inorganic particles 4 suitable for the dry method are used, and no solvent such as water required for molding by a wet method is added to the above-mentioned mixture. However, when manufacturing the heat insulating material, in order to prevent the inorganic particles 4 and other powders from flying and making the handling of the raw materials difficult, a small amount of water or other solvents may be added within the range considered as a dry method. For example, by adding a small amount of solvent such as water to the mixture, the scattering of inorganic particles during manufacturing can be suppressed.

[0239] In addition, the thermal insulation material uses a core-sheath structured binder fiber as a material, and the melting point of the first organic material constituting the core is higher than the melting point of the second organic material constituting the sheath. Therefore, when the mixture is heated, the core can remain and the sheath can be melted. Afterwards, after cooling, the outer peripheral surface of the core (organic fiber 1) is covered with the second organic material containing inorganic particles 4, so that the inorganic particles 4 can be retained. The organic fiber 1 coated with the inorganic particles 4 has an apparent coarse fiber diameter, so it is high in strength compared to the strength of the organic fiber 1 alone. In addition, since the binder fibers in the mixture exist in irregular directions, the organic fibers 1 are coated with each other in the area where the binder fibers are in contact with each other to form a three-dimensional skeleton. As a result, the overall shape of the thermal insulation material can be further maintained at a higher strength.

[0240] It should be noted that even when an organic fiber without a core-sheath structure is used as a binder fiber, it is possible to leave the center of the organic fiber and melt only the surface, cover the surface with inorganic particles, or fuse the organic fibers to each other, depending on the temperature setting. However, when manufacturing a thermal insulation material, heating is usually performed from one side or both sides perpendicular to the thickness direction. Since a material with high thermal insulation performance is used, strict temperature management is required to raise the surface side of the sheet and the center side in the thickness direction to the same temperature.

[0241] On the other hand, when a binder fiber having a core-sheath structure in which the melting point of the first organic material constituting the core is higher than the melting point of the second organic material constituting the sheath is used, a temperature can be set so that the core is easily left and the sheath is melted. As a result, in the obtained thermal insulation material, the organic fibers 1 are fused to each other on both the surface side and the center side to form a skeleton for maintaining the strength of the sheet, and the fused portion 5 containing the inorganic particles 4 is formed on the surface of the organic fibers 1. Therefore, as a material for the thermal insulation material, it is preferable to use the binder fiber having the core-sheath structure described above.

[0242] It should be noted that, as described above, after the insulating material and the mica sheet 51 are stacked, the surface of their stack can be coated with a film or the like. As the polymer film, there can be cited films composed of polyimide, polycarbonate, PET, polyphenylene sulfide, polyetherimide, cross-linked polyethylene, flame retardant chloroprene rubber, polyvinylidene fluoride, rigid vinyl chloride, polybutylene terephthalate, PTFE, PFA, FEP, ETFE, rigid PCV, flame retardant PET, polystyrene, polyethersulfone, polyamide-imide, polyacrylonitrile, polyethylene, polypropylene, polyamide, etc. It should be noted that there is no particular limitation on the method of coating the surface with a film, and there can be cited a method of attaching with an adhesive or the like, a method of coating the insulating material and the mica sheet 51 with a film, a method of accommodating the insulating material and the mica sheet 51 in a bag-shaped film, etc.

[0243] Next, in the method for producing the heat transfer suppressing sheet 50 of the present embodiment, binder fibers and heating conditions preferably used, and other binder materials are described.

[0244] <Binder Fiber>

[0245] In the present embodiment, when the core-sheath structured binder fiber 3 is used, there is no particular limitation as long as the melting point of the first organic material constituting the core is higher than the melting point of the second organic material constituting the sheath. As the first organic material constituting the core, at least one selected from polyethylene terephthalate, polypropylene and nylon can be used. In addition, as the second organic material constituting the sheath, at least one selected from polyethylene terephthalate, polyethylene, polypropylene and nylon can be selected.

[0246] If the melting point of the first organic material constituting the core is sufficiently higher than the melting point of the second organic material constituting the sheath, the setting margin of the heating temperature in the heating process can be expanded, and the temperature setting for obtaining a more desired structure can be made easier. For example, the melting point of the first organic material is preferably higher than the melting point of the second organic material by 60°C or more, more preferably higher by 70°C or more, and further preferably higher by 80°C or more.

[0247] It should be noted that the above-mentioned adhesive fiber 3 having a core-sheath structure is generally commercially available, and the materials constituting the core and the sheath may be the same or different from each other. Examples of adhesive fibers in which the core and the sheath are made of the same material and have different melting points include, for example, a case where the core and the sheath are made of polyethylene terephthalate, a case where they are made of polypropylene, and a case where they are made of nylon. Examples of adhesive fibers in which the core and the sheath are made of different materials include a case where the core is made of polyethylene terephthalate and the sheath is made of polyethylene; a case where the core is made of polypropylene and the sheath is made of polyethylene, and a case where the core is made of polypropylene and the sheath is made of polyethylene.

[0248] In this embodiment, the melting point of the second organic material constituting the sheath of the binder fiber 3 means the melting temperature at which the second organic material starts to melt and deform, and softening accompanied by shape change is also considered as a type of melting and deformation. The melting point of the sheath of the binder fiber can be measured, for example, by the following method.

[0249] The binder fiber to be measured is arranged in such a manner as to be in contact with the glass fiber having a higher melting point, and is heated from room temperature to, for example, 200°C at a heating rate of 5°C / min, and then cooled to room temperature. At this time, if the surface of the binder fiber undergoes melting deformation and is fused at the portion in contact with the glass fiber, or if the cross-sectional shape of the binder fiber changes, it can be determined that the melting point of the second organic material constituting the sheath portion is 200°C or less. In this embodiment, the heating temperature is varied, and the fusion state of the binder fiber and the glass fiber after cooling or the cross-sectional shape of the binder fiber is observed by the above method, thereby determining the melting point of the second organic material constituting the sheath portion.

[0250] (Content of Binder Fiber)

[0251] In the present embodiment, when the binder fiber 3 of the core-sheath structure is used as the material, if the content of the binder fiber in the mixture is appropriately controlled, the reinforcing effect of the skeleton can be sufficiently obtained in the obtained thermal insulation material.

[0252] The content of the binder fiber 3 is preferably 5% by mass or more, more preferably 10% by mass or more, relative to the total mass of the mixture. In addition, if the content of the binder fiber 3 is too much, the content of the inorganic particles 4 is relatively reduced. Therefore, in order to obtain the desired thermal insulation performance, the content of the binder fiber 3 is preferably 25% by mass or less, more preferably 20% by mass or less, relative to the total mass of the mixture.

[0253] (Hot-melt powder)

[0254] In this embodiment, in addition to the above-mentioned binder fibers 3 and inorganic particles 4, the mixture may further contain a hot-melt powder as a binder material. The hot-melt powder is, for example, a powder containing a third organic material different from the above-mentioned first organic material and second organic material and having the property of melting by heating. By adding the hot-melt powder to the mixture and heating it, the hot-melt powder melts, and when it is subsequently cooled, it solidifies in a state containing the surrounding inorganic particles 4. Therefore, it is possible to further suppress the inorganic particles 4 from falling off from the heat insulating material.

[0255] As the hot-melt powder, there are hot-melt powders with various melting points, but it is sufficient to select a hot-melt powder with an appropriate melting point in consideration of the melting points of the core and sheath of the binder fiber used. Specifically, if the third organic material as a component constituting the hot-melt powder has a lower melting point than the first organic material constituting the organic fiber, it is possible to set a heating temperature for melting the sheath and the hot-melt powder while leaving the core. For example, if the melting point of the hot-melt powder is lower than the melting point of the sheath, the heating temperature during manufacturing can be set between the melting point of the core and the melting point of the sheath, and the heating temperature can be set more easily.

[0256] On the other hand, the type of hot-melt powder used can be selected in such a way that the melting point of the hot-melt powder is between the melting point of the core and the melting point of the sheath. When using a hot-melt powder with such a melting point, after the sheath and the hot-melt powder are melted, when they are cooled and solidified, the organic fiber (core) 1 and the molten sheath around it, as well as the hot-melt powder present in the gaps between the inorganic particles 4 are solidified first. As a result, the position of the organic fiber 1 can be fixed, and then the molten sheath is melted onto the organic fiber to easily form a three-dimensional skeleton. Therefore, the strength of the entire sheet can be further improved.

[0257] If the melting point of the third organic material constituting the hot-melt powder is sufficiently lower than the melting point of the first organic material constituting the core, the setting margin of the heating temperature in the heating process can be expanded, and the temperature setting for obtaining a more desired structure can be made easier. For example, the melting point of the first organic material is preferably higher than the melting point of the third organic material by 60°C or more, more preferably higher by 70°C or more, and further preferably higher by 80°C or more.

[0258] It should be noted that the melting point of the hot-melt powder (third organic material) is preferably 80° C. or higher, more preferably 90° C. or higher. In addition, the melting point of the hot-melt powder (third organic material) is preferably 180° C. or lower, more preferably 150° C. or lower. Components constituting the hot-melt powder include polyethylene, polyester, polyamide, ethylene vinyl acetate, and the like.

[0259] (Content of hot-melt powder)

[0260] In order to suppress the falling of inorganic particles, when the mixture contains a hot-melt powder, even a trace amount thereof can obtain the effect of suppressing the falling of powder. Therefore, the content of the hot-melt powder is preferably 0.5% by mass or more, more preferably 1% by mass or more relative to the total mass of the mixture.

[0261] On the other hand, if the content of the hot-melt powder is increased, the content of the inorganic particles 4 etc. will be relatively reduced. Therefore, in order to obtain the desired thermal insulation performance, the content of the hot-melt powder is preferably 5% by mass or less, more preferably 4% by mass or less relative to the total mass of the mixture.

[0262] <Heating conditions>

[0263] When a core-sheath structured binder fiber is used as the material of the heat insulating material, the heating temperature in the heating process is preferably a temperature higher than the melting point of the second organic material constituting the sheath portion and lower than the melting point of the first organic material constituting the core portion. By setting such a heating temperature, as described above, the strength of the sheet can be ensured by the core portion on either the surface side or the center side of the sheet, and the inorganic particles 4 can be retained by the cladding portion 5.

[0264] Specifically, the heating temperature in the heating step is preferably set to be 10° C. or higher than the melting point of the second organic material constituting the sheath, and more preferably 20° C. or higher. On the other hand, the heating temperature is preferably set to be 10° C. or lower than the melting point of the first organic material constituting the core, and more preferably 20° C. or lower.

[0265] The heating time is not particularly limited, but is preferably set to a heating time that allows the sheath portion to be sufficiently melted, and can be set, for example, to a time of 3 minutes to 15 minutes.

[0266] In the case of a material containing a hot-melt powder as the heat insulating material, the heating temperature in the heating process is preferably set to be 10°C or higher than the higher one of the melting point of the second organic material constituting the sheath and the melting point of the third organic material constituting the hot-melt powder, and more preferably set to be 20°C or higher. On the other hand, the heating temperature is preferably set to be 10°C or lower than the melting point of the first organic material constituting the core, and more preferably set to be 20°C or lower. By setting the heating temperature to such a temperature, a strong skeleton can be formed, the strength of the sheet can be further improved, and the inorganic particles 4 can be prevented from falling off by the cladding portion 5 and the like.

[0267] <Thickness of Heat Transfer Suppression Sheet>

[0268] The thickness of the heat transfer suppression sheet of this embodiment is not particularly limited, and is preferably 0.05 mm or more and 10 mm or less. If the thickness is 0.05 mm or more, sufficient compressive strength can be obtained. On the other hand, if the thickness is 10 mm or less, good thermal insulation of the heat transfer suppression sheet can be obtained.

[0269] [Battery Pack]

[0270] An example of a battery pack to which the heat transfer suppressing sheet 50 according to an embodiment of the present invention is applied is as described above. Figure 2Here, we use Figure 2 The structure and effect of the battery pack are described in detail. Figure 2 The heat insulating material 10 in the heat transfer suppressing sheet 50 shown may be replaced with other heat insulating materials other than the heat insulating materials having the above-mentioned various structures within the scope of the present invention.

[0271] like Figure 2 As shown, the battery pack 100 has a plurality of battery cells 20a, 20b, 20c, and a heat transfer suppression sheet 50 of the present embodiment, and the plurality of battery cells are connected in series or in parallel. For example, the heat transfer suppression sheet 50 of the present embodiment is sandwiched between the battery cells 20a and 20b, and between the battery cells 20b and 20c. In addition, the battery cells 20a, 20b, 20c and the heat transfer suppression sheet 50 are housed in the battery case 30.

[0272] It should be noted that the heat transfer suppressing sheet 50 is as described above.

[0273] In the battery pack 100 configured in this way, even if a battery cell 20a reaches a high temperature, the heat transfer suppressing sheet 50 having a heat transfer suppressing effect is present between the battery cell 20a and the battery cell 20b, thereby suppressing the heat transfer to the battery cell 20b.

[0274] In addition, since the heat transfer suppression sheet 50 of the present embodiment has the mica sheet 51, when the battery cell 20a is broken due to high temperature and scattered objects are generated, the mica sheet 51 can be used to protect the heat insulating material 10 and the adjacent battery cell 20b. Therefore, the influence of the scattered objects on the battery cell 20b can be suppressed, and the heat insulating material 10 can be suppressed from being damaged, and high heat insulation can be maintained between the battery cell 20a and the battery cell 20b.

[0275] It should be noted that the battery pack 100 of this embodiment is not limited to Figure 2 For example, the heat transfer suppression sheet 50 is not only disposed between the battery cells 20a and 20b, and between the battery cells 20b and 20c, but also disposed between the battery cells 20a, 20b, 20c and the battery case 30, or attached to the inner surface of the battery case 30.

[0276] In the battery pack 100 configured in this way, when a battery cell catches fire, it is possible to suppress the flame from spreading to the outside of the battery case 30. For example, the battery pack 100 of this embodiment is sometimes used in an electric vehicle (EV) or the like, and is arranged under the floor of the passengers. In this case, even if a battery cell catches fire, the safety of the passengers can be ensured.

[0277] In addition, since the heat transfer suppression sheet 50 is not only sandwiched between the battery cells but can also be arranged between the battery cells 20a, 20b, 20c and the battery case 30, there is no need to re-produce fireproof materials, etc., and a low-cost and safe battery pack 100 can be easily constructed.

[0278] In the battery pack of this embodiment, the heat transfer suppression sheet 50 disposed between the battery cells 20a, 20b, 20c and the battery case 30 may be in contact with the battery cells or may have a gap therebetween. However, if there is a gap between the heat transfer suppression sheet 50 and the battery cells 20a, 20b, 20c, deformation of the battery cells can be tolerated even when the temperature of any one of the plurality of battery cells rises and the volume expands.

[0279] It should be noted that the heat transfer suppression sheet 50 of this embodiment can be made into various shapes according to its manufacturing method. Therefore, it can cope with any shape without being affected by the shape of the battery cells 20a, 20b, 20c and the battery case 30. Specifically, in addition to square batteries, it can also be applied to cylindrical batteries, flat batteries, etc.

[0280] Various embodiments have been described above, but the present invention is certainly not limited to such examples. Those skilled in the art can certainly think of various variations or modifications within the scope of the claims, and it should be understood that they also belong to the technical scope of the present invention. In addition, the various components in the above embodiments can also be arbitrarily combined within the scope of the utility model.

[0281] In addition, the present application is based on the Japanese patent application (Japanese Patent Application No. 2023-053783) filed on March 29, 2023 and the Japanese patent application (Japanese Patent Application No. 2024-042573) filed on March 18, 2024, the contents of which are incorporated herein by reference.

[0282] Explanation of symbols

[0283] 1. Organic Fiber

[0284] 3. Adhesive Fiber

[0285] 4Inorganic particles

[0286] 5. Cladding

[0287] 6,47 Fiber bundle

[0288] 7 empty holes

[0289] 8. Gap

[0290] 10,40,60,70,80,90,110 insulation materials

[0291] 11 fiber layer

[0292] 12 composite layers

[0293] 13 Grassroots

[0294] 14 Matrix

[0295] 15Inorganic fiber

[0296] 16Fiber Department

[0297] 17.2 Organic Materials

[0298] 18 Parent Material Department

[0299] 20a, 20b, 20c battery cells

[0300] 28 air layers

[0301] 30 battery housing

[0302] 31 Contact Department

[0303] 32 base

[0304] 33 branches

[0305] 42 Area 1

[0306] 43 Area 2

[0307] 50 Heat transfer suppression sheet

[0308] 51 Mica Sheet

[0309] 100 battery pack

Claims

1. A heat transfer suppression sheet, It is characterized in that It has: Insulation materials; as well as The mica sheet is laminated on at least one of a first surface and a second surface perpendicular to the thickness direction of the thermal insulation material.

2. The heat transfer suppressing sheet according to claim 1, It is characterized in that The thermal insulation material has a plurality of three-dimensionally connected pores.

3. The heat transfer suppressing sheet according to claim 1, It is characterized in that The thermal insulation material has a cladding portion.

4. The heat transfer suppressing sheet according to claim 3, It is characterized in that The thermal insulating material has a fiber layer including the welded portion on at least a portion of the first surface and the second surface.

5. The heat transfer suppressing sheet according to claim 4, It is characterized in that The fiber layer extends in a stripe shape in a direction substantially parallel to the surface of the heat insulating material.

6. The heat transfer suppressing sheet according to claim 1, It is characterized in that The surface of the heat insulating material has a first region and a second region, and the first region and the second region form a sea-island structure, where the first region corresponding to the sea portion surrounds the second region corresponding to the island portion.

7. The heat transfer suppressing sheet according to claim 1, It is characterized in that Fiber bundles having a length of 20 mm or more and extending in stripes exist on the surface of the thermal insulation material.

8. The heat transfer suppressing sheet according to claim 7, It is characterized in that The fiber bundles are connected to form a mesh shape.

9. The heat transfer suppressing sheet according to claim 1, It is characterized in that The thickness of the heat transfer suppressing sheet is 0.05 mm or more and 10 mm or less.

10. A battery pack, It is characterized in that The heat transfer suppressing sheet comprises a plurality of battery cells and the heat transfer suppressing sheet according to any one of claims 1 to 9, wherein the plurality of battery cells are connected in series or in parallel.

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