Heat transfer suppression sheet, heat transfer suppression member, and battery pack

Abstract

Provided is a heat transfer suppression sheet capable of maintaining a heat transfer suppression effect even when a resin substrate is burned out by high heat or flame from a battery cell-caused thermal runaway. Also, provided is a battery pack having higher safety, capable of maintaining a heat transfer suppression effect even when a resin substrate is burned out by high heat or flame from a thermal runaway battery cell. A heat transfer suppression sheet (1) includes a resin substrate (10), first inorganic particles (20), and second inorganic particles (30) having a melting point lower than that of the first inorganic particles (20). A heat transfer suppression member (60) has a heat insulation layer (50) on the surface of the heat transfer suppression sheet (1). A battery pack (100) comprises the heat transfer suppression sheet (1) or the heat transfer suppression member (60) interposed between battery cells (110), wherein the battery cells (110) are connected in series or in parallel.

Description

Heat transfer suppression sheet, heat transfer suppression member, and battery pack

[0001] The present invention relates to a heat-transfer-suppressing sheet and a heat-transfer-suppressing member for use in a battery pack, and also to a battery pack including the heat-transfer-suppressing sheet or the heat-transfer-suppressing member.

[0002] In recent years, from the viewpoint of environmental protection, active development has been made of electric vehicles, hybrid vehicles, and the like that are driven by electric motors. These electric vehicles, hybrid vehicles, and the like are equipped with assembled batteries in which multiple battery cells are connected in series or parallel to serve as the power source for the driving electric motor.

[0003] Lithium-ion secondary batteries, which offer higher capacity and power output than lead-acid batteries or nickel-metal hydride batteries, are primarily used for battery cells. If a battery cell experiences thermal runaway, such as a sudden temperature rise caused by an internal short circuit or overcharging, and continues to generate heat, the high heat and flames from the battery cell experiencing thermal runaway may spread to other adjacent battery cells. Therefore, heat-transfer-suppressing sheets are placed between battery cells to prevent the transfer of thermal runaway and the spread of fire.

[0004] For example, Patent Document 1 describes a heat-transfer-suppressing sheet that is made of a urethane resin composition containing a urethane resin, a trimerization catalyst, and a flame retardant. When the fire-resistant material is heated by high heat from a battery cell that has experienced thermal runaway or by a fire, the fire-resistant material expands and blocks the spaces between the battery cells, preventing or delaying heat transfer to adjacent battery cells and the spread of fire.

[0005] Japanese Patent Application Publication No. 2018-206604

[0006] However, although the heat transfer suppression sheet of Patent Document 1 contains a flame retardant, depending on the scale and extent of the high heat and flames from the battery cell that has experienced thermal runaway, it is expected that the urethane resin that is the base material of the insulating material will be burned and will no longer function as an insulating material.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a heat-transfer-suppressing sheet that can maintain its heat-transfer suppression effect even if the resin substrate is burned away by the high heat or flame from a battery cell that has experienced thermal runaway. Another aim of the present invention is to provide a battery assembly that can maintain its heat-transfer suppression effect even if the resin substrate is burned away by the high heat or flame from a battery cell that has experienced thermal runaway, thereby providing a safer battery assembly.

[0008] The above object of the present invention is achieved by the heat transfer-suppressing sheet having the following configuration [1].

[0009] [1] A heat-transfer-suppressing sheet comprising a resin substrate, first inorganic particles, and second inorganic particles having a melting point lower than that of the first inorganic particles.

[0010] Preferred embodiments of the present invention relating to the heat transfer-suppressing sheet relate to the following [2] to [8].

[0011] [2] The heat-transfer-suppressing sheet according to [1], wherein the first inorganic particles and the second inorganic particles are dispersed in the resin substrate. [3] The heat-transfer-suppressing sheet according to [1], wherein a first heat-transfer-suppressing sheet in which the first inorganic particles are dispersed in the resin substrate and a second heat-transfer-suppressing sheet in which the second inorganic particles are dispersed in the resin substrate are laminated together. [4] The heat-transfer-suppressing sheet according to [3], wherein the first heat-transfer-suppressing sheets and the second heat-transfer-suppressing sheets are alternately laminated together to form multiple layers. [5] The heat-transfer-suppressing sheet according to any one of [1] to [4], further comprising an inorganic hydrate as the third inorganic particles. [6] The inorganic hydrate is 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[7] The heat-transfer-suppressing sheet according to any one of [1] to [6], wherein the melting point of the second inorganic particles is 700°C or lower. [8] The heat-transfer-suppressing sheet according to any one of [1] to [7], further comprising a phosphate compound.

[0012] The above object of the present invention is achieved by the following configuration [9] relating to the heat transfer suppressing member.

[0013] [9] A heat-transfer-suppressing member comprising the heat-transfer-suppressing sheet according to any one of [1] to [8], and a heat-insulating layer on the surface thereof.

[0014] The above object of the present invention is achieved by the following battery pack configuration

[10] or

[11] .

[0015]

[10] A battery pack, characterized in that the heat-transfer-suppressing sheet according to any one of [1] to [8] is interposed between battery cells, and the battery cells are connected in series or in parallel.

[11] A battery pack, characterized in that the heat-transfer-suppressing member according to [9] is interposed between battery cells with the heat-transfer-suppressing sheet abutting against the battery cells, and the battery cells are connected in series or in parallel.

[0016] Even if the resin substrate of the heat transfer-suppressing sheet of the present invention is burned due to exposure to high heat or flames from a battery cell that has experienced thermal runaway, the second inorganic particles with a low melting point will melt and penetrate between the first inorganic particles, which have excellent heat resistance, to form a three-dimensional network, thereby maintaining the excellent heat resistance of the first inorganic particles and suppressing heat transfer to adjacent battery cells and the spread of fire.

[0017] Furthermore, the heat transfer-suppressing member of the present invention has a heat insulating layer on the surface of the heat transfer-suppressing sheet, which provides additional heat insulating performance and further enhances the heat transfer suppressing effect.

[0018] Therefore, a battery pack equipped with the heat transfer suppression sheet or heat transfer suppression member of the present invention is highly safe because it more effectively prevents high heat and flames from a battery cell that has experienced thermal runaway from being transmitted to adjacent battery cells and spreading to other cells.

[0019] Fig. 1 is a cross-sectional view schematically showing one embodiment of the heat-transfer-suppressing sheet of the present invention. Fig. 2 is a cross-sectional view schematically showing another embodiment of the heat-transfer-suppressing sheet of the present invention. Fig. 3 is a cross-sectional view schematically showing one embodiment of the heat-transfer-suppressing member of the present invention. Fig. 4 is a schematic diagram showing a battery assembly (part 1) including the heat-transfer-suppressing sheet of the present invention shown in Fig. 1. Fig. 5 is a schematic diagram showing a battery assembly (part 2) including the heat-transfer-suppressing member of the present invention shown in Fig. 3.

[0020] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0021] 1 is a cross-sectional view schematically illustrating one embodiment of a heat-transfer-suppressing sheet 1 of the present invention. As shown in the figure, the heat-transfer-suppressing sheet 1 has first inorganic particles 20 and second inorganic particles 30 having a melting point lower than that of the first inorganic particles 20 dispersed in a resin substrate (also referred to as an "organic substrate") 10.

[0022] There are no restrictions on the type of resin that can be used for the resin substrate 10, but because the temperature of the battery cell can rise to nearly 150°C during charging and discharging, the resin substrate must have sufficient heat resistance to prevent melting at the battery cell's rising temperature. It must also be able to adapt to the expansion and contraction that accompanies the charging and discharging of the battery cell. Considering these characteristics, suitable resins include urethane resin, silicone resin, fluororesin, polyether ether ketone resin, polyamide-imide resin, polyimide resin, and polycarbonate resin.

[0023] It is also preferable that the material has elasticity in order to improve adhesion to the battery cell, and for this purpose it may further contain a foaming agent or foaming assistant.

[0024] The first inorganic particles 20 are particles made of an inorganic material having a higher melting point and higher heat resistance than the second inorganic particles 30, and are preferably, for example, oxide particles. Examples of oxide particles include silica (SiO ２ ), titania (TiO ２ ), zirconia (ZrO ２ ), zircon (ZrSiO ４ ), barium titanate (BaTiO ３ ), zinc oxide (ZnO) and alumina (Al ２ O ３ In particular, silica is a component with high heat insulating properties, and titania is a component with a higher refractive index than other metal oxides, and is highly effective in scattering light and blocking radiant heat in a high-temperature region of 500°C or higher, so it is most preferable to use silica and titania as the oxide particles.

[0025] Furthermore, inorganic hydrate particles can be blended as third inorganic particles (not shown) in place of a portion of the first inorganic particles 20. When inorganic hydrates receive high heat from a battery cell experiencing thermal runaway and reach a temperature above their thermal decomposition initiation temperature, they undergo thermal decomposition and release their own water of crystallization, thereby lowering the temperature of the battery cell and its surroundings, thereby exhibiting a so-called "endothermic effect." After releasing their water of crystallization, they instantly become oxides, which are porous and exhibit heat insulation properties due to their countless air pores.

[0026] A specific example of an inorganic hydrate is 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.

[0027] For example, aluminum hydroxide contains about 35% water of crystallization, and as shown in the following formula, it thermally decomposes, releasing the water of crystallization and exhibiting an endothermic effect. After releasing the water of crystallization, it becomes a porous alumina (Al ２ O ３ ) and functions as a heat insulating material. 2Al(OH) ３ →Al ２ O ３ +3H ２ O

[0028] In a battery cell that has experienced thermal runaway, the temperature rises sharply to over 200°C and, depending on the type of battery, may continue to rise to at least around 700°C, and in some cases to around 1000°C or even higher. The thermal decomposition onset temperatures of the inorganic hydrates listed above are approximately 200°C for aluminum hydroxide, approximately 330°C for magnesium hydroxide, approximately 580°C for calcium hydroxide, approximately 200°C for zinc hydroxide, approximately 350°C for iron hydroxide, approximately 300°C for manganese hydroxide, approximately 300°C for zirconium hydroxide, and approximately 300°C for gallium hydroxide. All of these temperatures roughly overlap with the temperature range of the rapid temperature rise in a battery cell that has experienced thermal runaway, and can efficiently suppress the temperature rise, making them preferable inorganic hydrates.

[0029] The second inorganic particles 30 are particles made of an inorganic material having a lower melting point than the first inorganic particles 20. Therefore, the second inorganic particles 30 may be selected depending on the type of the first inorganic particles 20, and among these, particles called low-melting glass are preferred.

[0030] The type of low-melting glass is not particularly limited, but examples thereof include soda-lime glass, non-alkali glass, borosilicate glass, potash glass, crystal glass, titanium crystal glass, barium glass, strontium glass, alumina silicate glass, soda-zinc glass, soda-barium glass, and vanadium glass (V ２ O ５ ) and the like. Examples of borosilicate glass include SiO ２ -B ２ O ３ -ZnO-based glass, SiO ２ -B ２ O ３ -Bi ２ O３ Crystal glass is glass containing PbO, and SiO ２ - PbO-based glass, SiO ２ -PbO-B ２ O ３ Glass, SiO ２ -B ２ O ３ -PbO-based glass, etc. Barium glass includes BaO-SiO ２ In consideration of the environment, lead-free glass is preferred.

[0031] The heat transfer-suppressing sheet 1 preferably further contains a flame retardant in addition to the resin substrate 10, the first inorganic particles 20, and the second inorganic particles 30. The inclusion of a flame retardant enhances the flame retardancy of the heat transfer-suppressing sheet 1. There are no particular restrictions on the flame retardant, and halogen-based flame retardants, phosphorus-based flame retardants, antimony-based flame retardants, etc. may be appropriately selected and used. However, phosphorus-based flame retardants are preferred, and phosphate compounds are particularly suitable.

[0032] The heat-transfer-suppressing sheet 1 contains the above-mentioned components and is interposed between battery cells in a battery pack. If a battery cell experiences thermal runaway, the resulting high heat and flames may be transferred to the heat-transfer-suppressing sheet 1, causing the resin substrate 10 to burn. However, even if the resin substrate 10 were to burn, the molten second inorganic particles 30, which have a lower melting point, would flow between the first inorganic particles 20, which have a higher heat resistance, and function as a binder (binding material) that binds the first inorganic particles 20 together, thereby forming a three-dimensional network of the first inorganic particles 20.

[0033] Furthermore, since the time required to build a network by the first inorganic particles 20 is preferably as short as possible, the melting point of the second inorganic particles 30 (note: the softening point in the case of glass particles) is preferably low, and is preferably 700° C. or lower, more preferably 500° C. or lower, and even more preferably 400° C. or lower. However, if the melting point of the second inorganic particles 30 is too low, not only will softening and other problems occur during normal use of the battery cell, but the viscosity when melted will be too low, making it difficult to build and maintain a network by the first inorganic particles 20. Therefore, the melting point is preferably 200° C. or higher.

[0034] The network of the first inorganic particles 20 prevents heat transfer and fire spread to adjacent battery cells.

[0035] In order to more effectively establish a network using the first inorganic particles 20, the amount of the first inorganic particles 20 in the heat transfer-suppressing sheet 1 is preferably 70 to 95% by volume, and more preferably 80 to 90% by volume, relative to the total amount of the first inorganic particles 20 and the second inorganic particles 30. When third inorganic particles (inorganic hydrates) are further incorporated, the amount is an amount that replaces a portion of the first inorganic particles 20. There are no particular restrictions on the average particle size of the first inorganic particles 20; however, as the particle size increases for the same mass, the number of particles decreases and the particle spacing increases, making it more difficult to establish a network using the first inorganic particles 20. The average particle size of the first inorganic particles 20 is preferably 10 to 1,000 nm, and more preferably 10 to 100 nm. When third inorganic particles (inorganic hydrates) are incorporated, it is also preferable that the particle size be approximately the same as that of the first inorganic particles 20.

[0036] To facilitate the construction of a network of the first inorganic particles 20, the blending amount of the second inorganic particles 30 in the heat transfer-suppressing sheet 1 is preferably 5 to 30 volume %, more preferably 10 to 20 volume %, relative to the total amount of the blended first inorganic particles 20 and second inorganic particles 30. While there are no particular limitations on the average particle size of the second inorganic particles 30, the greater the number of second inorganic particles 30, the more easily the molten second inorganic particles 30 flow between the first inorganic particles 20, so the second inorganic particles 30 are preferably small in diameter. Even with the same mass, the smaller the particle size, the greater the number of particles, and small-diameter particles take less time to melt overall than large-diameter particles, so they function favorably as a binder. The average particle size of the second inorganic particles 30 is preferably 10 to 1,000 nm, more preferably 10 to 100 nm.

[0037] The heat transfer-suppressing sheet 1 can be obtained by adding first inorganic particles 20 and second inorganic particles 30, and optionally a foaming agent, a foaming aid, a flame retardant, and the like, to a resin that will become the resin substrate 10 and kneading them together. However, if there is a large difference in specific gravity between the first inorganic particles 20 and the second inorganic particles 30, the first inorganic particles 20 and the second inorganic particles 30 may be unevenly distributed in the resin substrate 10. Therefore, as shown in Fig. 2, a first heat transfer-suppressing sheet 41 in which the first inorganic particles 20 are dispersed in the resin substrate 10 and a second heat transfer-suppressing sheet 42 in which the second inorganic particles 30 are dispersed in the resin substrate 10 may be laminated together to form a single heat transfer-suppressing sheet 1A.

[0038] In such a heat-transfer-suppressing sheet 1A, the resin base material 10 of the first heat-transfer-suppressing sheet 41 and the resin base material 10 of the second heat-transfer-suppressing sheet 42 are burned away at approximately the same time. Furthermore, because there is no uneven distribution of the first inorganic particles 20 and the second inorganic particles 30, the molten second inorganic particles 30 of the second heat-transfer-suppressing sheet 42 are more likely to flow more uniformly between the first inorganic particles 20 of the first heat-transfer-suppressing sheet 41. Therefore, since the resin base material 10 of the first heat-transfer-suppressing sheet 41 and the resin base material 10 of the second heat-transfer-suppressing sheet 42 are burned away in the same way, it is preferable that the resins used are the same.

[0039] In addition, although the heat transfer inhibiting sheet 1A has a two-layer structure consisting of a first heat transfer inhibiting sheet 41 and a second heat transfer inhibiting sheet 42 in FIG. 2, it may also have a multi-layer structure in which the first heat transfer inhibiting sheet 41 and the second heat transfer inhibiting sheet 42 are alternately stacked (not shown).

[0040] In the above manufacturing method, the first inorganic particles 20 can be partially replaced with the third inorganic particles (inorganic hydrate).

[0041] [Heat Transfer-Inhibiting Member] The heat transfer-inhibiting sheet 1 or heat transfer-inhibiting sheet 1A can also be used as a heat transfer-inhibiting member by attaching (or laminating) a heat insulating layer to the surface. Figure 3 shows one example of this, showing a heat transfer-inhibiting member 60 in which a heat insulating layer 50 is attached to one surface of the heat transfer-inhibiting sheet 1 shown in Figure 1. Although not shown, the heat insulating layer 50 can also be attached to the heat transfer-inhibiting sheet 1A shown in Figure 2.

[0042] The heat transfer suppression member 60 combines the heat transfer suppression effect of the heat transfer suppression sheet 1 (1A) with the insulating effect of the insulating layer 50, and the higher the insulating performance of the insulating layer 50, the better. For example, the following insulating materials can be mentioned.

[0043] The heat insulating material can include inorganic particles and organic fibers. The heat insulating material has a plurality of three-dimensionally connected pores between the inorganic particles and the organic fibers. The organic fibers have welded portions covering at least a portion of their surfaces, and at least a portion of the inorganic particles are welded to the surfaces of the organic fibers by the welded portions. As a result, the surfaces of the organic fibers are covered with the inorganic particles.

[0044] The insulation material configured in this manner has multiple three-dimensionally connected pores, which provide the effect of air insulation and improve insulation performance. Furthermore, the insulation material contains highly flexible organic fibers, which not only enhances the flexibility of the insulation material but also makes it easier for the organic fibers to entangle with each other, improving the overall strength of the insulation material. Furthermore, the presence of pores improves the cushioning properties of the insulation material as a whole, allowing the insulation material to absorb the expansion of the battery cells when they expand during charging and discharging. Therefore, damage to the insulation layer 50 containing such insulation material can be suppressed.

[0045] It is also preferable that at least some of the pores are connected to the surface of the thermal insulation material and open outward. With this pore configuration, high heat from a battery cell experiencing thermal runaway is transferred to the thermal insulation layer 50 through the heat transfer-suppressing sheet 1 (1A). Even if the organic fibers or the like are decomposed, the decomposition gases do not remain inside the thermal insulation material but are released to the outside through the pores. Therefore, this also contributes to preventing destruction of the thermal insulation layer 50.

[0046] As described above, when the welded portions on the outer surface of the organic fibers fix the inorganic particles to the organic fibers, it is possible to prevent the inorganic particles from falling off (powdering). Therefore, even when the battery cell expands and compressive stress or impact is applied to the insulating material, the insulating material can be more effectively maintained in its shape, and a decrease in the insulating effect due to compressive deformation of the insulating layer 50 can be prevented.

[0047] The insulating material preferably contains inorganic fibers. Since inorganic fibers are resistant to decomposition even at high temperatures, even if the battery cell experiences thermal runaway (for example, heating to 800°C or higher) and the organic fibers of the insulating material decompose, the inorganic fibers remain, allowing the insulating material to reliably maintain its shape. Furthermore, the flexible organic fibers tend to become entangled with the relatively hard inorganic fibers, forming a three-dimensional skeleton (aggregate) with open spaces between them, further improving the strength of the insulating material.

[0048] The heat insulating material may be produced by either a wet method or a dry method.

[0049] Furthermore, a mica sheet may be laminated on at least one of the first and second surfaces of the insulating material, which are perpendicular to the thickness direction. Mica has excellent heat resistance and insulating properties, and mica sheets, which are made by processing a mica-containing material into a sheet, also have excellent impact resistance. Therefore, if a battery cell explodes and debris is generated, the mica sheet protects the insulating layer 50, preventing damage to the insulating layer 50.

[0050] "Battery Pack (Part 1)] FIG. 4 is a schematic diagram showing a battery pack 100 including the heat-transfer-suppressing sheet 1 shown in FIG. 1. As shown in the figure, the battery pack 100 has the heat-transfer-suppressing sheet 1 interposed between the battery cells 110. The battery cells 110 are connected in series or in parallel by bus bars. Although not shown in the figure, the battery cells 110 may be placed on a cooling plate (not shown). The heat-transfer-suppressing sheet 1 and the battery cells 110, and if a cooling plate is used, the cooling plate, are housed in a battery case 120.

[0051] As described above, even if the resin substrate 10 is burned, the heat transfer suppression sheet 1 can ensure safety even if a certain battery cell 110 experiences thermal runaway, because the first inorganic particles 20 form a network to suppress heat transfer.

[0052] Although not shown in the figures, a heat-transfer-restricting sheet 1A can also be used, in which case either the first heat-transfer-restricting sheet 41 or the second heat-transfer-restricting sheet 42 may be in contact with the battery cell 110.

[0053] [Battery Assembly (Part 2)] Fig. 5 is a schematic diagram showing a battery assembly 100 including the heat-transfer-suppressing member 60 shown in Fig. 3. As shown in the figure, the heat-transfer-suppressing member 60 is interposed between the battery cells 110, and the heat-transfer-suppressing member 60 also has a heat-transfer-suppressing sheet 1 on the other side of the heat-insulating layer 50. In other words, the heat-transfer-suppressing sheet 1 is provided on both sides of the heat-insulating layer 50, and the battery cells 110 abut against the heat-transfer-suppressing sheet 1.

[0054] The battery cells 40 are connected in series or parallel by bus bars, and the heat transfer suppressing member 60 , the battery cells 110 , and, if a cooling plate is used, the cooling plate are housed in the battery case 120 .

[0055] The heat-transfer-suppressing member 60 adds the heat-insulating effect of the heat-transfer-suppressing layer 50 to the heat-transfer-suppressing effect of the heat-transfer-suppressing sheet 1 , thereby further improving the safety of the battery pack 100 .

[0056] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0057] This application is based on a Japanese patent application (Patent Application No. 2023-145489) filed on September 7, 2023, the contents of which are incorporated herein by reference.

[0058] REFERENCE SIGNS LIST 1, 1A Heat-transfer-suppressing sheet 10 Resin substrate (organic substrate) 20 First inorganic particles 30 Second inorganic particles 41 First heat-transfer-suppressing sheet 42 Second heat-transfer-suppressing sheet 50 Heat-insulating layer 60 Heat-transfer-suppressing member 100 Battery pack 110 Battery cell 120 Battery case

Claims

1. A heat-transfer-suppressing sheet comprising a resin substrate, first inorganic particles, and second inorganic particles having a melting point lower than that of the first inorganic particles.

2. The heat transfer-suppressing sheet according to claim 1, wherein the first inorganic particles and the second inorganic particles are dispersed in the resin substrate.

3. The heat-transfer-inhibiting sheet according to claim 1, characterized in that a first heat-transfer-inhibiting sheet in which the first inorganic particles are dispersed in the resin base material and a second heat-transfer-inhibiting sheet in which the second inorganic particles are dispersed in the resin base material are laminated together.

4. The heat transfer suppressing sheet according to claim 3, wherein the first heat transfer suppressing sheet and the second heat transfer suppressing sheet are alternately laminated in multiple layers.

5. The heat transfer-suppressing sheet according to any one of claims 1 to 4, further comprising an inorganic hydrate as a third inorganic particle.

6. The inorganic hydrate is 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 6. The heat transfer-suppressing sheet according to claim 5, wherein the heat transfer-suppressing material is at least one selected from the group consisting of fluororesin, fluororesin, fluoroisotope, fluorosulfone, fluoroisotope and fluoroisotope.

7. A heat transfer-suppressing sheet as described in any one of claims 1 to 4, characterized in that the melting point of the second inorganic particles is 700°C or lower.

8. The heat transfer-suppressing sheet according to any one of claims 1 to 4, further comprising a phosphate compound.

9. A heat transfer suppressing member comprising the heat transfer suppressing sheet according to any one of claims 1 to 4 and a heat insulating layer on the surface thereof.

10. A battery pack comprising: a heat transfer-suppressing sheet according to any one of claims 1 to 4 inserted between battery cells; and the battery cells are connected in series or parallel.

11. A battery pack comprising: a heat transfer suppression member as described in claim 9, which is interposed between battery cells with the heat transfer suppression sheet abutting the battery cells; and the battery cells are connected in series or parallel.

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