Heat insulation material

Abstract

To provide a heat insulation material with excellent thermal insulation properties and adjustable constraining load on battery cells.SOLUTION: A heat insulation material 1, in a laminate of a plurality of battery cells, is disposed between any arbitrary pair of the battery cells adjacent to each other in a laminating direction. The heat insulation material 1 comprises a pre-compacted heat insulation layer 10 having a pre-compressed body 11 formed by pre-compressing a precursor with thermal insulation properties and a constraining member 12 that covers the pre-compressed body 11 and maintains the compressed state of the pre-compressed body 11. Furthermore, the heat insulation material is configured to include a first heat insulation layer and a second heat insulation layer arranged in the laminating direction and the first heat insulation layer may serve as the pre-compressed heat insulation layer. In this case, at least either one of the precursor of the pre-compressed heat insulation layer and the second heat insulation layer is configured to include aerogel.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a thermal insulator disposed between adjacent battery cells in a battery pack housing a plurality of battery cells, and particularly to a thermal insulator using aerogel. [Background technology]

[0002] Hybrid vehicles and electric vehicles are equipped with battery packs containing multiple battery cells. In the battery pack, a stack of multiple battery cells is housed in a housing and secured by fastening members on both sides in the stacking direction. Heat insulating material is placed between adjacent battery cells in the stacking direction to prevent heat transfer and thermal runaway in the event of abnormal heat generation in the battery cells.

[0003] For example, Patent Document 1 describes a heat insulating material including a heat insulating layer containing silica aerogel, infrared shielding particles, and inorganic fibers, and a substrate supporting the heat insulating layer. Patent Document 2 describes a heat transfer-suppressing sheet including two heat insulating layers composed of inorganic particles, inorganic fibers, etc., and a metal layer disposed between them. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 181443 [Patent Document 2] Japanese Patent Publication No. 2020-165483 [Patent Document 3] Patent Publication No. 2021-136101 Summary of the Invention [Problem to be solved by the invention]

[0005] Insulating materials disposed between battery cells (hereinafter sometimes simply referred to as "cells") desirably have not only insulating properties but also a biasing force for fixing the cells in place, in order to prevent the cells from shifting position due to vibrations during vehicle operation. Furthermore, it is desirable for the insulating materials to be deformable to accommodate the expansion and contraction of the cells that occurs during charging and discharging. For example, when a cell expands during charging, the resulting compressive force reduces the thickness of the insulating material, and at the same time, a reaction force of at least a certain value must be generated to bias the cell and prevent the cell from shifting position. If the insulating material has a relatively large spring constant in the thickness direction and is therefore inflexible, it will be difficult for the insulating material to deform in response to the expansion of the cell, resulting in a large biasing force (constraint load) on the cell. This may result in excessive compression of the cell, potentially causing damage or deterioration of the cell. Conversely, if the insulating material is too flexible, it may not be able to provide the biasing force necessary to fix the cell, potentially resulting in cell shifting or other problems.

[0006] In this regard, Patent Documents 1 and 2 do not consider the biasing force of the insulating material on the cells or its ability to conform to cell deformation. The heat transfer-suppressing sheet described in Patent Document 2 has a metal layer disposed between two insulating layers, but this merely improves the sheet's mechanical strength against the compressive force caused by cell expansion. On the other hand, Patent Document 3 describes a battery module in which an elastic member is disposed between adjacent cells. However, the elastic member described in Patent Document 3 is not an insulating material for suppressing heat transfer between cells. As described in paragraph

[0010] and elsewhere, this document merely arranges a relatively flexible elastic member to reduce the restraining force when the cells expand.

[0007] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide an insulating material for use in a battery pack, which has excellent insulating properties and is capable of adjusting the restraint load on the battery cells. [Means for solving the problem]

[0008] (1) In order to solve the above problems, the insulating material disclosed herein is an insulating material that is arranged between any pair of adjacent battery cells in a stack of multiple battery cells in the stacking direction, and is characterized by having a pre-compressed insulating layer that has a pre-compressed body formed by pre-compressing a precursor having insulating properties, and a restraining member that covers the pre-compressed body and maintains the compressed state of the pre-compressed body.

[0009] In the thermal insulation material of the present disclosure, the load characteristics of the thermal insulation material are optimized by pre-compressing a precursor having thermal insulation properties. Figure 1 shows a schematic diagram of the load-displacement curve of a pre-compressed thermal insulation layer. In Figure 1, the curve of the pre-compressed thermal insulation layer is shown by a thick solid line. For comparison, Figure 1 also shows a curve of a thermal insulation layer (uncompressed thermal insulation layer A) made of the same material as the precursor of the pre-compressed thermal insulation layer in an uncompressed state by a thick dashed dotted line, and a curve of a thermal insulation layer (uncompressed thermal insulation layer B) with a larger spring constant than that of the uncompressed thermal insulation layer A by a thin dashed dotted line.

[0010] In a pre-compressed insulating layer, the displacement relative to the load is reduced by the amount of pre-compression. Therefore, as shown in Figure 1, the displacement of the curve for the pre-compressed insulating layer is zero until a certain load is reached. Therefore, a pre-compressed insulating layer can increase the spring constant in the region where the displacement is relatively small. This allows the cell to be biased with a relatively large load even when the cell is assembled or contracts due to discharge. On the other hand, in the non-compressed insulating layer B, which has a larger spring constant than the non-compressed insulating layer A, the rise in load relative to the displacement (slope of the curve) is large, and the load value becomes too large in the region where the displacement is large. In contrast, the slope of the curve for the pre-compressed insulating layer is gentle, the same as that of the non-compressed insulating layer A. Therefore, a pre-compressed insulating layer can reduce the biasing force (constraint load) on the cell in the region where the displacement is large, such as when the cell expands.

[0011] In this way, the insulating material of the present disclosure can ensure a biasing force for fixing the cells when the cells are assembled, when they contract due to discharge, etc., and when they expand due to charging, the insulating material can deform to follow the deformation of the cells while biasing the cells to an extent that does not apply an excessive load to the cells. Therefore, the insulating material of the present disclosure can suppress damage and deterioration of the cells, and is less likely to cause misalignment even when the cells expand and contract, allowing high thermal insulation properties to be maintained.

[0012] (2) In the above configuration, the precursor may include an aerogel. Aerogel is a porous material with a skeleton formed by interconnected primary particles of approximately several nanometers. Pores of approximately several nanometers to 100 nanometers exist between the skeleton, and many of these are mesopores smaller than the mean free path of air. This microporous structure primarily suppresses conduction and convection, among the three modes of heat transfer (conduction, convection, and radiation), resulting in extremely low thermal conductivity of the aerogel. Therefore, this configuration can improve the thermal insulation properties of the thermal insulator. Depending on the drying method used to produce the aerogel, those dried at normal pressure are sometimes called "xerogels," those dried under supercritical conditions are called "aerogels," and those freeze-dried are called "cryogels." In this specification, however, these are collectively referred to as "aerogels."

[0013] (3) In any of the above configurations, the precursor may be a molded body of a composition containing aerogel powder. With this configuration, it is easy to optimize load characteristics by compression.

[0014] (4) In the above configuration (2) or (3), the aerogel may be silica aerogel, which has a good balance between the size of the skeleton and the size of the pores and exhibits excellent heat insulating properties.

[0015] (5) In any of the above configurations, the restraining member may be configured to include one or more materials selected from a resin film and an inorganic fiber cloth. With this configuration, the pre-compressed body can be easily covered, and the compressed state of the pre-compressed body can be maintained by, for example, using a pouch, adhesive, or a fixing member.

[0016] (6) In the configuration of (1) above, the structure may be configured to include a first insulating layer and a second insulating layer arranged in the stacking direction, the first insulating layer being the pre-compressed insulating layer, and at least one of the precursor of the pre-compressed insulating layer and the second insulating layer having an aerogel.

[0017] In the insulating material of this configuration, one of the two insulating layers, the first insulating layer, is a pre-compressed insulating layer having a pre-compressed body of a precursor having insulating properties, thereby optimizing the load characteristics of the insulating material.

[0018] Figure 2 shows a schematic diagram of the load-displacement curve of the laminate of the first and second insulating layers (the laminate of the present disclosure). In Figure 2, the curve of the laminate of the present disclosure is shown by a thick solid line. For comparison, Figure 2 also shows a curve of an insulating layer (uncompressed insulating layer A) made of the same material as the precursor of the first insulating layer in an uncompressed state by a thick dashed dotted line, and a curve of the second insulating layer (uncompressed insulating layer B) by a thin dashed dotted line (the spring constant k of uncompressed insulating layer B). B > Spring constant k of the incompressible insulating layer A A ), and the curve for the laminate of the uncompressed heat insulating layer A and the uncompressed heat insulating layer B (AB laminate) is shown by a thin solid line.

[0019] When two layers A and B with different spring constants are simply laminated, the spring constant k of the AB laminate is AB is the spring constant k of each layer A , k B The combined spring constant [k AB =(k A ·k B ) / (k A +k B) ). In other words, the composite spring constant is smaller than the spring constant of the uncompressed insulating layer A. Therefore, as shown by the thin solid line in Figure 2, the slope of the curve for the AB laminate is smaller than the slope of the curve for the uncompressed insulating layer A.

[0020] In contrast, when a pre-compressed insulating layer and an uncompressed insulating layer B are stacked (the laminate of the present disclosure), the curve shown by the thick solid line in Figure 2 follows the curve of the second insulating layer (uncompressed insulating layer B) from the initial stage (displacement 0) to a certain displacement (x1 on the horizontal axis), but thereafter the slope is smaller than that of the curve of the second insulating layer. In other words, the curve is nonlinear, with a small change in load relative to displacement. Here, displacement x1 corresponds to the point where the imaginary line of the curve of the laminate of the present disclosure, shown by the thick dotted line in Figure 2, intersects with the curve of the uncompressed insulating layer B. In this way, the laminate of the present disclosure can increase the spring constant in regions where the displacement is relatively small and decrease the spring constant in regions where the displacement is large. Therefore, with this configuration, the cell can be biased with a relatively large load when the cell is assembled and contracts due to discharge, and the biasing force (constraint load) on the cell can be reduced when the cell expands due to charge.

[0021] In addition, at least one of the first and second insulating layers contains aerogel, which has low thermal conductivity. This improves the thermal insulation properties of the insulating material. Both the first and second insulating layers may be made of aerogel, or only one of them may be made of aerogel. Because aerogel is a relatively expensive material, using it in combination with other insulating materials can reduce costs.

[0022] (7) In the above-mentioned (6), the precursor of the pre-compressed heat insulating layer may be a molded body of a composition containing aerogel powder. With this configuration, it is easy to optimize the load characteristics by compression.

[0023] (8) In the above configuration (7), the molded body may further contain one or more selected from infrared shielding particles, inorganic fibers, and a dispersant for the aerogel powder.

[0024] As mentioned above, the use of aerogels can achieve high thermal insulation by suppressing mainly conduction and convection, among the three forms of heat transfer (conduction, convection, and radiation). Radiation is the phenomenon in which heat is transferred by electromagnetic waves, and the higher the temperature, the greater the amount of radiant energy emitted. Therefore, in high-temperature environments, radiation is the primary cause of heat transfer. Therefore, by using infrared-shielding particles that can suppress heat transfer due to radiation, heat transfer due to radiation can be suppressed in addition to conduction and convection, achieving high thermal insulation not only at room temperature but also at high temperatures of 500°C or higher. When the molded body contains inorganic fibers, the mechanical strength of the molded body is improved and aerogel particle shedding can be suppressed. Aerogel powder is poorly compatible with water and difficult to disperse. Therefore, when water is used in the production of a composition, adding an amphiphilic dispersant can improve the dispersibility of the aerogel powder. Furthermore, adding a dispersant can improve the compactability of silica aerogel powder.

[0025] (9) In any of the above (6) to (8), the precursor of the precompressed heat insulating layer may be a molded body of a composition containing aerogel powder, and the second heat insulating layer may be made of one material selected from the group consisting of a microporous heat insulating material, an aerogel-supported fibrous body, and glass wool. This configuration allows the construction of a heat insulating material with desired load characteristics.

[0026] (10) In any of the above (6) to (9), the aerogel may be silica aerogel, which has a good balance between the size of the skeleton and the size of the pores and exhibits excellent heat insulating properties. [Effects of the Invention]

[0027] In the thermal insulation material disclosed herein, the pre-compressed insulating layer allows the restraint load on the battery cell to be adjusted within a desired range, thereby suppressing damage and deterioration of the cell, and maintaining high thermal insulation properties by preventing misalignment even when the cell expands and contracts. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram of a load-displacement curve of a pre-compressed insulating layer. [Figure 2] 3 is a schematic diagram of a load-displacement curve of a stack of a first insulation layer and a second insulation layer. FIG. [Figure 3] FIG. 2 is a cross-sectional view in the thickness direction of the heat insulating material of the first embodiment. [Figure 4] FIG. 6 is a cross-sectional view in the thickness direction of the heat insulating material of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an embodiment of the heat insulating material of the present disclosure will be described.

[0030] First Embodiment [composition] First, the configuration of the heat insulating material of this embodiment will be described. FIG. 3 shows a cross-sectional view of the heat insulating material of this embodiment in the thickness direction. The thickness direction of the heat insulating material (the vertical direction in FIG. 3) corresponds to the stacking direction of the battery cell stack. As shown in FIG. 3, the heat insulating material 1 includes a pre-compressed heat insulating layer 10. The pre-compressed heat insulating layer 10 includes a pre-compressed body 11 and a restraining member 12. The pre-compressed body 11 is a rectangular sheet with a thickness of 1 mm. The pre-compressed body 11 is manufactured by compressing a molded body (precursor) of a composition containing silica aerogel powder, silicon carbide (infrared shielding particles), glass fiber (inorganic fiber), and polyethylene oxide (PEO, dispersant) in the thickness direction. The restraining member 12 covers the entire pre-compressed body 11 and maintains the compressed state of the pre-compressed body 11. The restraining member 12 is made of two glass cloths 120a and 120b. The thickness of the glass cloths 120a and 120b is 100 μm. The glass cloths 120a and 120b are arranged with the pre-compressed body 11 sandwiched therebetween, and are thermally pressed together at the overlapping portions around the pre-compressed body 11.

[0031] [Action and effect] Next, the effects of the heat insulating material of this embodiment will be described. The heat insulating material 1 can adjust the restraining load on adjacent battery cells by adjusting the compression state of the pre-compressed body 11 so that it exerts a large biasing force in areas with small displacement and a small biasing force in areas with large displacement. This prevents damage and deterioration to the cells, and maintains high thermal insulation properties even when the cells expand and contract, making it less likely to shift position. Furthermore, the pre-compressed body 11 contains infrared-shielding particles and inorganic fibers in addition to silica aerogel. Therefore, the pre-compressed body 11 has high mechanical strength and exhibits excellent thermal insulation properties not only at room temperature but also at high temperatures of 500°C or higher. Furthermore, the glass cloths 120a and 120b have relatively low thermal conductivity and high heat resistance. Therefore, the restraining member 12 has excellent shape retention even at high temperatures, allowing the pre-compressed body 11 to maintain its compressed state.

[0032] Second Embodiment [composition] First, the configuration of the heat insulating material of this embodiment will be described. Fig. 4 shows a cross-sectional view of the heat insulating material of this embodiment in the thickness direction. The thickness direction of the heat insulating material (the vertical direction in Fig. 4) corresponds to the stacking direction in the stack of battery cells. As shown in Fig. 4, the heat insulating material 2 includes a first heat insulating layer 20, a second heat insulating layer 21, and an exterior material 22. The first heat insulating layer 20 and the second heat insulating layer 21 are stacked in the thickness direction.

[0033] The first insulating layer 20 is a pre-compressed insulating layer and includes a pre-compressed body 23 and a restraining member 24. The pre-compressed body 23 is in the form of a rectangular sheet with a thickness of 1 mm. The pre-compressed body 23 is the same as the pre-compressed body 11 of the first embodiment, and is manufactured by compressing a molded body (precursor) of a composition containing silica aerogel powder, silicon carbide, glass fiber, and PEO in the thickness direction. The restraining member 24 is made of a polyethylene terephthalate (PET) film. The restraining member 24 covers the entire pre-compressed body 23 and maintains the compressed state of the pre-compressed body 23.

[0034] The second heat insulating layer 21 is in the form of a rectangular sheet with a thickness of 1 mm. The second heat insulating layer 21 is an aerogel-supported fibrous body in which silica aerogel is supported on a glass fiber nonwoven fabric.

[0035] The exterior material 22 is made of two glass cloths 220a and 220b. The thickness of each of the glass cloths 220a and 220b is 100 μm. The glass cloths 220a and 220b are arranged on either side of a laminate of the first insulating layer 20 and the second insulating layer 21, and are thermocompression bonded at the overlapping portions around the periphery of the laminate.

[0036] [Action and effect] Next, the effects of the thermal insulation material of this embodiment will be described. The thermal insulation material of this embodiment and the thermal insulation material of the first embodiment have similar effects in the parts that share the same configuration. According to the thermal insulation material 2 of this embodiment, the compression state of the first insulating layer 20 can be adjusted to provide a large biasing force in areas with small displacement and a small biasing force in areas with large displacement, thereby adjusting the restraining load on adjacent battery cells. This can suppress damage and deterioration of the cells, and even if the cells expand and contract, they are less likely to shift position, maintaining high thermal insulation. In addition, the first insulating layer 20 and the second insulating layer 21 are entirely covered with the exterior material 22. This increases the mechanical strength of the thermal insulation material 2 and prevents the silica aerogel that constitutes the second insulating layer 21 from falling off. In addition, the glass cloths 220a and 220b have relatively low thermal conductivity and high heat resistance. Therefore, the thermal insulation material 2 has excellent shape retention at high temperatures.

[0037] <Other forms> Two embodiments of the heat insulating material of the present disclosure have been described above. However, the embodiments are not limited to the above-described embodiments. Various modifications and improvements that can be made by those skilled in the art are also possible.

[0038] [Insulation material usage] The heat insulating material of the present disclosure is used in a battery pack in which multiple battery cells are arranged side by side in a predetermined direction. The type of battery cells is not particularly limited. Examples include lithium-ion batteries and nickel-metal hydride batteries. The arrangement of the heat insulating material of the present disclosure and its size relative to the battery cells are not particularly limited. The heat insulating material of the present disclosure may be arranged between adjacent cells in the stacking direction, or may be arranged between cells at both ends in the stacking direction and fastening members, etc. The thickness of the heat insulating material may be determined appropriately taking into consideration the arrangement space, ensuring insulation between cells, etc. The size, such as the thickness, of the heat insulating material may be changed depending on the arrangement location in the battery pack.

[0039] [Insulation composition] (1) The insulating material of the present disclosure comprises a pre-compressed insulating layer having a pre-compressed body formed by pre-compressing a precursor having insulating properties, and a restraining member that covers the pre-compressed body and maintains the compressed state of the pre-compressed body.

[0040] (i) Pre-compressed body Precompressed bodies are produced by compressing a precursor with insulating properties. The precursor can be a single material, a mixture, or a composite, as long as it has insulating properties. Examples of precursors include aerogel-supported fibrous bodies in which aerogel is supported on a fibrous substrate, molded bodies of aerogel-containing compositions, microporous insulation materials, and glass wool. For example, the thermal conductivity of the precursor is preferably 0.05 W / m·K or less. From the perspective of improving insulating properties, it is desirable for the precursor to contain aerogel. Among these, silica aerogel is preferred due to its excellent chemical stability and good balance between the skeleton size and pore size. For example, when using powdered aerogel, other components such as infrared-shielding particles, inorganic fibers, aerogel dispersants, binders to bind the constituent components, and flame retardants may be used in combination.

[0041] Infrared-shielding particles absorb heat from a heat source and re-emit it from the surface of the heat source, thereby blocking radiant heat from the heat source and contributing to improved insulation, especially at high temperatures. Examples include silicon carbide, kaolinite, silicon nitride, mica, alumina, zirconia, aluminum nitride, zirconium silicate, cerium oxide, boron carbide, manganese oxide, tin oxide, and iron oxide. Inorganic fibers physically entangle around the aerogel particles, improving the mechanical strength of the pre-compressed body and preventing the aerogel particles from falling off. Suitable examples include ceramic fibers such as glass fiber and alumina fiber. Examples of dispersants include surfactants and water-soluble oligomers with both polar and non-polar components in the side chain. Examples of binders include inorganic binders such as colloidal silica and aqueous emulsion binders. Known flame retardants, such as halogen-based, phosphorus-based, and metal hydroxide-based, may be used. The precursor can be produced by placing a mixture of aerogel powder and, if necessary, other components in a mold and pressurizing the mixture. Alternatively, the precursor can be produced by mixing aerogel powder and, if necessary, other components with a solvent such as water to form a slurry composition, which is then applied to a binding member and dried.

[0042] The precursor can be pre-compressed by placing the precursor together with a restraining member in a press or the like and applying pressure in the thickness direction. The compression conditions can be appropriately determined so as to obtain the desired load characteristics.

[0043] (ii) Restraining member The restraining member is not particularly limited as long as it can cover the pre-compressed body and maintain the compressed state of the pre-compressed body. For example, a resin film such as polyethylene (PE), polypropylene (PP), or PET, or a woven or nonwoven fabric made from inorganic fibers such as glass fiber or metal fiber may be used.

[0044] (iii) Exterior materials The thermal insulation material of the present disclosure may include an exterior covering on the outside of the pre-compressed insulating layer. The exterior covering may be disposed on only one side of the pre-compressed insulating layer in the thickness direction (the stacking direction of the battery cells), or may be disposed on both sides so as to sandwich the pre-compressed insulating layer. Alternatively, the exterior covering may cover the entire pre-compressed insulating layer.

[0045] Examples of materials for the exterior packaging include cloth, resin, and paper. The form of the exterior packaging is not particularly limited, and examples include woven fabric, nonwoven fabric, film, and sheet. The exterior packaging may consist of a single layer, or may be a laminate of two or more layers of the same or different materials. For example, fabrics (woven fabrics) and nonwoven fabrics made from inorganic fibers such as glass fiber and metal fiber, and fire-resistant insulating paper made as a composite of pulp and magnesium silicate, have relatively low thermal conductivity and exhibit excellent shape retention even in high-temperature environments. Among these, glass fiber nonwoven fabric, glass cloth, aluminum glass cloth, alkaline earth silicate (AES) wool paper, and polyimide fiber nonwoven fabric are preferred due to their high heat resistance.

[0046] (2) The thermal insulation material of the present disclosure may be composed solely of a pre-compressed insulating layer, or may be composed of a pre-compressed insulating layer in combination with other layers. For example, the thermal insulation material may be composed of a first insulating layer and a second insulating layer stacked in the stacking direction of the battery cells, with the first insulating layer being the pre-compressed insulating layer. In this configuration, from the viewpoint of thermal insulation, it is preferable to include aerogel in at least one of the first insulating layer and the second insulating layer. As with the precursor of the pre-compressed body described above, silica aerogel is preferred as the form in which aerogel is used, and other components such as infrared-shielding particles, inorganic fibers, aerogel dispersants, binders for binding the constituent components, and flame retardants may also be used in combination.

[0047] The second insulating layer can be in any form, such as a simple substance, a mixture, or a composite, as long as it has insulating properties. Examples include aerogel-supported fibrous bodies in which aerogel is supported on a fibrous substrate, molded bodies of compositions containing aerogel, microporous insulating materials, and glass wool. For example, the thermal conductivity of the second insulating layer should desirably be 0.05 W / m K or less.

[0048] When the insulating material of the present disclosure is constructed with two insulating layers, the material of the pre-compressed body that constitutes the first insulating layer (pre-compressed insulating layer) and the material of the second insulating layer may be the same or different. For example, by comparing the spring constants of the materials before compression, the one with the smaller spring constant can be used as a precursor and pre-compressed.

[0049] The first and second insulation layers may or may not be fixed. If they are fixed, they may be bonded by adhesive or by thermocompression. Even in a configuration in which the insulation material is composed of two layers, the exterior material may be arranged so as to cover at least a portion of the first and second insulation layers. The exterior material is as described above in (1)(iii). [Explanation of symbols]

[0050] 1: Insulating material, 2: Insulating material, 10: Pre-compressed insulating layer, 11: Pre-compressed body, 12: Restraining member, 20: First insulating layer, 21: Second insulating layer, 22: Exterior material, 23: Pre-compressed body, 24: Restraining member, 120a, 120b, 220a, 220b: Glass cloth.

Claims

1. A thermal insulator disposed between any pair of adjacent battery cells in a stack of a plurality of battery cells, An insulating material characterized by comprising a pre-compressed insulating layer having a pre-compressed body formed by pre-compressing a precursor having insulating properties, and a restraining member that covers the pre-compressed body and maintains the compressed state of the pre-compressed body.

2. The thermal insulation material of claim 1 , wherein the precursor comprises an aerogel.

3. The heat insulating material according to claim 1 , wherein the precursor is a molded body of a composition containing aerogel powder.

4. 4. The heat insulating material according to claim 2, wherein the aerogel is silica aerogel.

5. The heat insulating material according to claim 1 , wherein the restraining member comprises at least one material selected from the group consisting of a resin film and an inorganic fiber cloth.

6. A first insulating layer and a second insulating layer are provided, which are arranged in the stacking direction, the first insulation layer is the pre-compressed insulation layer; 10. The insulation of claim 1, wherein at least one of the precursor of the pre-compressed insulating layer and the second insulating layer comprises an aerogel.

7. 7. The heat insulating material according to claim 6, wherein the precursor of the pre-compressed heat insulating layer is a molded body of a composition comprising aerogel powder.

8. The heat insulating material according to claim 7 , wherein the molded body further comprises one or more selected from the group consisting of infrared shielding particles, inorganic fibers, and a dispersant for the aerogel powder.

9. the precursor of the pre-compressed heat insulating layer is a molded body of a composition containing the aerogel powder, The heat insulating material according to claim 6, wherein the second heat insulating layer is made of one material selected from the group consisting of a microporous heat insulating material, an aerogel-supported fibrous body, and glass wool.

10. 7. The heat insulating material according to claim 6, wherein the aerogel is silica aerogel.

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