Heat transfer inhibiting sheet and battery pack

Abstract

The present application provides a heat transfer inhibiting sheet which can accurately align the positions of a heat insulating material and an elastic sheet, can inhibit the destruction of a battery case and the reduction of battery performance caused by the deformation of a battery cell, and can further inhibit the heat propagation between the battery cells at the time of abnormality, and can reduce the raw material cost. The heat transfer inhibiting sheet (50) has: a heat insulating material (10) including inorganic particles; an elastic sheet (51a, 51b) laminated on a first surface (10a) and a second surface (10b) of the heat insulating material (10) orthogonal to the thickness direction; and a joint portion (55a, 55b) joining the heat insulating material (10) and the elastic sheet (51a, 51b). Opposed regions (45a, 45b) of the heat insulating material (10) and the elastic sheet (51a, 51b) facing each other include a joint region (44a, 44b) in which the joint portion (55a, 55b) is present and a non-joint region (41a, 41b) in which the joint portion (55a, 55b) is not present.

Description

Technical Field

[0001] This invention relates to a heat transfer suppressor and a battery pack having the heat transfer suppressor. Background Technology

[0002] In recent years, from an environmental protection perspective, there has been active development of electric vehicles or hybrid vehicles powered by electric motors. These electric vehicles or hybrid vehicles are equipped with battery packs consisting of multiple battery cells connected in series or parallel to power the electric motors used for driving the motors.

[0003] Furthermore, this battery cell primarily uses lithium-ion secondary batteries, which offer higher capacity and output compared to lead-acid and nickel-metal hydride batteries. However, in the event of thermal runaway, such as a battery cell experiencing a rapid temperature rise due to internal short circuits or overcharging, and continuing to heat up, the heat from the thermally runaway cell can propagate to adjacent cells, potentially causing thermal runaway in those cells as well.

[0004] In addition, when a battery cell experiences thermal runaway, gas is generated inside the cell, causing the internal pressure to rise and resulting in deformation of the cell. In cases of significant deformation, the casing may be damaged.

[0005] Such deformation of individual battery cells also occurs slightly during charge-discharge cycles of battery cells in a battery pack (i.e., "normal use"). As the internal pressure of the battery cells repeatedly rises and falls during charge-discharge, the battery cells are repeatedly pressed and relaxed by the casing, which becomes a cause of reduced battery performance.

[0006] As a countermeasure against the aforementioned thermal runaway, for example, Patent Document 1 proposes a heat-prevention sheet comprising: a rubber sheet composed of a rubber-like elastomer; a heat insulation sheet laminated on both sides of the rubber sheet to reduce heat transfer between multiple adjacent heat sources; and an adhesive layer between the rubber sheet and the heat insulation sheet to bond the heat insulation sheet to both sides of the rubber sheet.

[0007] The heat-prevention sheet described in Patent Document 1, due to its rubber sheet composition, provides cushioning and acts as a protective component to prevent damage to the heat insulation sheet. Furthermore, Patent Document 1 describes how the adhesive layer contains a specific low-thermal-conductivity filler, which reduces heat transfer between multiple heat sources and improves heat-prevention performance.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2023-62546 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, the anti-burn sheet involved in the aforementioned patent document 1 uses an adhesive layer containing a specific low thermal conductivity filler, which increases the raw material cost of the anti-burn sheet and requires an adhesive layer manufacturing process, which may make the manufacturing process more complicated.

[0013] Furthermore, as mentioned above, the adhesive layer contains fillers with low thermal conductivity, which can reduce heat transfer between heat sources, but its effect is not sufficient. For example, the adhesive layer has lower thermal insulation properties compared to the insulation material, so if the adhesive layer is placed between the insulation material and the rubber sheet, there is a tendency for the insulation performance to decrease. In addition, during the manufacturing of the anti-burn sheet, if the adhesive constituting the adhesive layer penetrates into the interior of the porous rubber sheet or insulation sheet, the pores will be blocked by the adhesive, sometimes further reducing the insulation performance. Furthermore, if the adhesive layer is flammable, it may also ignite when the anti-burn sheet is exposed to high temperatures, failing to fully perform its function as an anti-burn sheet. Moreover, the presence of the adhesive layer may sometimes reduce the compressibility of the anti-burn sheet, failing to achieve the desired compressibility characteristics, resulting in reduced battery performance.

[0014] On the other hand, when a non-adhesive layer is used in order to suppress the reduction of thermal insulation, it is impossible to accurately align the thermal insulation material with the rubber sheet.

[0015] The present invention was made in view of the above-mentioned problems, and its object is to provide a heat transfer suppression sheet that can accurately align the heat insulation material with the elastic sheet, suppress the damage to the battery casing and the reduction in battery performance caused by the deformation of the battery cells, and further suppress the heat propagation between the battery cells in case of abnormality, and reduce the raw material cost; and to provide a battery pack that can suppress the heat propagation between the battery cells, and suppress the damage to the battery casing and the reduction in battery performance.

[0016] Methods for solving problems

[0017] The above-mentioned objective of the present invention is achieved by the following [1] configuration of the heat transfer suppression sheet.

[0018] [1] A heat transfer suppression sheet comprising: a heat insulation material containing inorganic particles; an elastic sheet laminated on at least one of a first surface and a second surface orthogonal to the thickness direction of the heat insulation material; and a joint for joining the heat insulation material and the elastic sheet, characterized in that... The opposing regions of the thermal insulation material and the elastic sheet include a jointed region where the joint exists and a non-jointed region where the joint does not exist.

[0019] Furthermore, the preferred embodiments of the present invention of the heat transfer inhibition sheet relate to the following [2] to

[14] .

[0020] [2] The heat transfer suppression sheet according to [1] is characterized in that the non-jointing region is located in the central part of the opposing region.

[0021] [3] The heat transfer suppression sheet according to [1] or [2] is characterized in that the engagement region is located near the end in the opposing region.

[0022] [4] The heat transfer suppression sheet according to any one of [1] to [3] is characterized in that the opposing region is a region surrounded by three or more sides, and the joining region is only located near one of the three or more sides.

[0023] [5] The heat transfer suppression sheet according to [4] is characterized in that the bonding region is formed to extend along one of the edges.

[0024] [6] The heat transfer suppression sheet according to any one of [1] to [3] is characterized in that the opposing region is a rectangular region enclosed by a set of long sides and a set of short sides orthogonal to the long sides, and the joining region is only located near one of the short sides of the set of short sides.

[0025] [7] The heat transfer suppression sheet according to [6] is characterized in that the bonding region is formed to extend along one of the short sides.

[0026] [8] The heat transfer inhibiting sheet according to any one of [1] to [7], characterized in that, The joint is formed only in a portion of the opposing regions to constitute the joint area. The non-jointed region extends from the boundary between the joined region and the non-jointed region to one end of the opposing region, where at one end of the opposing region, the thermal insulation material and the elastic sheet are configured to be separable.

[0027] [9] The heat transfer suppression sheet according to [8] is characterized in that the joint is formed at a position near the other end opposite to one end of the opposing region.

[0028]

[10] The heat transfer suppression sheet according to any one of [1] to [9] is characterized in that the joint is made of an adhesive for bonding the heat insulation material to the elastic sheet.

[0029]

[11] The heat transfer suppression sheet according to any one of [1] to [9] is characterized in that the joint is composed of a joint member for joining the heat insulation material to the elastic sheet.

[0030]

[12] The heat transfer inhibition sheet according to any one of [1] to

[11] is characterized in that the elastic sheet comprises at least one selected from synthetic rubber, natural rubber and thermoplastic elastomer.

[0031]

[13] The heat transfer suppression sheet according to any one of [1] to

[12] is characterized in that the heat insulation material further comprises organic fibers.

[0032]

[14] The heat transfer suppression sheet according to any one of [1] to

[13] is characterized in that it has a film covering the outer peripheral surface of the laminate containing the heat insulation material and the elastic sheet.

[0033] Furthermore, the above-mentioned objective of the present invention is achieved by the following configuration of the battery pack

[15] .

[0034]

[15] A battery pack having a plurality of battery cells and a heat transfer suppressor sheet as described in any one of [1] to

[14] , wherein the plurality of battery cells are connected in series or in parallel.

[0035] Invention Effects

[0036] The heat transfer suppression sheet of the present invention achieves excellent heat insulation performance due to its heat insulation material containing inorganic particles. Furthermore, since an elastic sheet is laminated on the heat insulation material, the elastic sheet absorbs the deformation of the battery cells, thus suppressing damage to the battery casing and degradation of battery performance. Additionally, because the opposing regions of the heat insulation material and the elastic sheet include both joined and unjoined regions, the joined regions allow for precise alignment, while the unjoined regions suppress degradation of heat insulation performance and compressive properties, thereby reducing material costs.

[0037] According to the battery pack of the present invention, since it has a heat transfer suppression sheet with high heat insulation and the ability to suppress battery casing damage and battery performance degradation, it is able to suppress thermal runaway of individual battery cells in the battery pack and the spread of flame to the outside of the battery casing. Attached Figure Description

[0038] Figure 1A This is a top view showing the heat transfer suppression sheet according to the first embodiment of the present invention.

[0039] Figure 1B yes Figure 1A A schematic cross-sectional view at line AA.

[0040] Figure 2This is a schematic cross-sectional view illustrating another structural example of the heat transfer suppression sheet according to the first embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram illustrating a battery pack according to an embodiment of the present invention.

[0042] Figure 4A This is a top view showing the heat transfer suppression sheet according to the second embodiment of the present invention.

[0043] Figure 4B yes Figure 4A A schematic cross-sectional view at the BB line.

[0044] Figure 5 This is a schematic diagram illustrating a state in which the heat-transfer suppression sheet according to the second embodiment of the present invention is configured such that the heat-insulating material and the elastic sheet can be separated in the non-jointed area.

[0045] Figure 6 This is a schematic cross-sectional view showing the heat transfer suppression sheet according to the third embodiment of the present invention.

[0046] Figure 7 This is a photographic representation of an example S1 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0047] Figure 8 It is Figure 7 The accompanying photograph shows an enlarged view of a portion of the insulation material.

[0048] Figure 9 This is a photographic representation of an example S2 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0049] Figure 10 This is a schematic diagram illustrating an example S3 of the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0050] Figure 11 It is Figure 10 A magnified diagram showing a portion of the image.

[0051] Figure 12 It is shown Figure 10 The attached diagram of the insulation material is a substitute photograph.

[0052] Figure 13 This is a photographic representation of an example S4 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0053] Figure 14 It is Figure 13The attached diagram shows an enlarged view of the structure of the insulation material.

[0054] Figure 15 It is shown Figure 13 The attached diagram is a substitute photograph of the cross-section of the insulation material shown.

[0055] Figure 16 This is a schematic diagram illustrating the structure of an example S5 of the heat-insulating material used in a heat transfer suppression sheet according to an embodiment of the present invention.

[0056] Figure 17 It is Figure 16 A magnified schematic diagram of part A of the insulation material shown.

[0057] Figure 18 This is a photographic representation of an example S6 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0058] Figure 19 It is shown Figure 18 The accompanying photograph shows other areas of the insulation material.

[0059] Figure 20 It is shown Figure 18 and Figure 19 The attached diagram is a substitute photograph of the cross-section of the insulation material shown.

[0060] Figure 21 This is a photographic representation of an example S7 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention.

[0061] Figure 22 It is Figure 21 The accompanying photograph shows an enlarged view of a portion of the insulation material.

[0062] Figure 23 This is a diagram illustrating an example of a method for specifying fiber bundle length. Figure 21 The attached photograph is an enlarged view of section A.

[0063] Figure 24 It is a diagram showing a mesh-like bundle of fibers. Figure 21 The attached photograph is a magnified view of part A. Detailed Implementation

[0064] To address the aforementioned issues, the inventors conducted in-depth research. The results showed that by bonding the thermal insulation material to the elastic sheet only in a portion of the structure, heat transfer between individual battery cells during abnormal conditions can be further suppressed, and raw material costs can also be reduced.

[0065] The following provides a detailed description of the heat transfer suppression sheet, its manufacturing method, and the battery pack involved in the embodiments of the present invention. It should be noted that the present invention is not limited to the embodiments described below, and can be implemented in any way without departing from the spirit of the invention. First, the heat transfer suppression sheet involved in the embodiments of the present invention will be described.

[0066] [Heat Transfer Inhibition Tablets]

[0067] [First Implementation Method]

[0068] Figure 1A This is a top view showing the heat transfer suppression sheet according to the first embodiment of the present invention. Figure 1B yes Figure 1A A schematic cross-sectional view at line AA. (See attached image.) Figure 1A and Figure 1B As shown, the heat transfer suppression sheet 50 according to the first embodiment includes a heat insulation material 10 and elastic sheets 51a and 51b respectively stacked on a first surface 10a and a second surface 10b orthogonal to the thickness direction of the heat insulation material 10. That is, in the heat transfer suppression sheet 50 according to the first embodiment, the heat insulation material 10 is held by a pair of elastic sheets 51a and 51b. It should be noted that the heat insulation material 10 has inorganic particles (not shown). The elastic sheets 51a and 51b are formed by processing the elastic material described later into a sheet shape.

[0069] Furthermore, to prevent positional misalignment, the thermal insulation material 10 and the elastic sheet 51a are joined in multiple regions via joints 55a, thereby forming joint regions 44a. However, in this embodiment, in the opposing regions 45a where the thermal insulation material 10 and the elastic sheet 51a face each other, other than the joint regions 44a, the thermal insulation material 10 and the elastic sheet 51a are not joined to each other, thereby forming non-jointed regions 41a. Similarly, the thermal insulation material 10 and the elastic sheet 51a are joined in multiple regions via joints 55b, thereby forming joint regions 44b. And in the opposing regions 45b where the thermal insulation material 10 and the elastic sheet 51b face each other, other than the joint regions 44b, the thermal insulation material 10 and the elastic sheet 51b are not joined to each other, thereby forming non-jointed regions 41b. The materials constituting the thermal insulation material 10, the elastic sheets 51a, and 51b will be described in detail later.

[0070] Figure 2 This is a schematic cross-sectional view illustrating another structural example of the heat transfer suppression sheet according to the first embodiment of the present invention. Figure 2The heat transfer suppression sheet 52 shown includes a heat-insulating material 10 and an elastic sheet 51a laminated on a first surface 10a orthogonal to the thickness direction of the heat-insulating material 10. The heat-insulating material 10 and the elastic sheet 51a are joined in multiple regions, thereby forming a joining region 44a. Furthermore, in the opposing regions 45a of the heat-insulating material 10 and the elastic sheet 51a, excluding the joining regions 44a, the heat-insulating material 10 and the elastic sheet 51a are not joined to each other, thereby forming a non-jointing region 41a. Additionally, regarding the materials constituting the heat-insulating material 10, the elastic sheet 51a, and the joining portion 55a, etc., [the following is unclear and requires further context]. Figure 1A and Figure 1B The heat transfer suppression sheet 50 shown has the same heat insulation material, elastic sheets 51a and 51b, and joints 55a and 55b.

[0071] In this embodiment, the joints 55a and 55b can be areas extending in a planar manner or points. When multiple point-like joints are densely distributed, the joint areas 44a and 44b sometimes represent an aggregation of multiple point-like joints. Furthermore, in this embodiment, the thermal insulation material 10 is bonded to the elastic sheets 51a and 51b using an adhesive, and the joints 55a and 55b are areas formed by the cured adhesive. However, the joints 55a and 55b do not necessarily need to be composed of an adhesive. The structure and materials of the joints 55a and 55b will be described in detail later.

[0072] The following is based on Figure 1A and Figure 1B Taking the heat transfer suppression sheet 50 shown as an example, the specific usage method will be explained. Figure 3 This is a schematic diagram illustrating a battery pack according to an embodiment of the present invention. Figure 3 As shown, the heat transfer suppression sheet 50 can be used by sandwiching the heat transfer suppression sheet 50 between multiple battery cells 20a, 20b, and 20c. Furthermore, the multiple battery cells 20a, 20b, and 20c are housed in the battery casing 30 in a series or parallel connection (connection configurations are not shown in the diagram), thereby forming the battery pack 100. Additionally, lithium-ion secondary batteries are preferably used as battery cells 20a, 20b, and 20c, but this is not a particular limitation, and other secondary batteries are also applicable.

[0073] In the heat transfer suppression sheet 50 according to the first embodiment described above, since it has a heat insulation material 10 containing inorganic particles, excellent heat insulation performance can be obtained between multiple battery cells 20a, 20b, and 20c. Therefore, for example, in the event of an abnormality in battery cell 20a and a temperature rise, heat propagation to battery cell 20b can be sufficiently suppressed. Furthermore, in the first embodiment, elastic sheets 51a and 51b are laminated on the first surface 10a and the second surface 10b of the heat insulation material 10. The elastic sheets 51 have the effect of suppressing deformation of battery cells 20a, 20b, and 20c and absorbing deformation of battery cells 20a, 20b, and 20c. That is, when battery cells 20a, 20b, and 20c deform during charging / discharging or in abnormal situations, the elastic sheets 51 suppress the deformation of battery cells 20a, 20b, and 20c, while also flexibly deforming with the deformation of battery cells 20a, 20b, and 20c. Therefore, it is possible to suppress the application of unnecessary stress to battery cells 20a, 20b, and 20c.

[0074] Furthermore, the heat insulation material 10 is joined to the elastic sheets 51a and 51b via joints 55a and 55b, respectively. Therefore, during the handling of the heat transfer suppression sheet 50 or its installation on the battery casing 30, misalignment between the two is prevented, ensuring accurate alignment of the heat insulation material and the elastic sheets. However, in this embodiment, the joints 55a and 55b are not formed on the entire surface of the opposing regions 45a and 45b where the heat insulation material 10 and the elastic sheets 51a and 51b face each other. These opposing regions 45a and 45b contain joining regions 44a and 44b with the joints 55a and 55b formed, and non-jointing regions 41a and 41b without the joints 55a and 55b formed. Therefore, the reduction in heat insulation performance and compression characteristics caused by the presence of the joints 55a and 55b can be suppressed.

[0075] Furthermore, since the joints 55a and 55b are formed only in a portion of the facing regions 45a and 45b of the insulating material 10 and the elastic sheets 51a and 51b, the amount of adhesive used can be reduced when the insulating material 10 is bonded to the elastic sheets 51a and 51b using an adhesive. Additionally, the reduction in insulation performance due to the presence of joints can be suppressed without using adhesives containing specific low thermal conductivity materials. Therefore, when using an adhesive, the manufacturing process of the adhesive can be simplified, the material cost of the heat transfer suppression sheet can be reduced, and the environmental impact can also be reduced.

[0076] In this invention, the size of the joining regions 44a and 44b is not particularly limited, as long as at least a portion of the opposing regions 45a and 45b of the insulating material 10 and the elastic sheets 51a and 51b contains non-joining regions 41a and 41b. Furthermore, in the non-joining regions, the insulating material 10 and the elastic sheets 51a and 51b can be in contact or separated. Additionally, to suppress the reduction in insulating performance and compressibility, it is preferable that the area of ​​the joining regions 44a and 44b is small within the range where the insulating material 10 and the elastic sheets 51a and 51b are mutually fixed. For example, relative to the area of ​​the opposing regions 45a and 45b of the insulating material 10 and the elastic sheets 51a and 51b, the area of ​​the joining regions 44a and 44b is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less.

[0077] Furthermore, in this invention, the positions of the joining regions 44a, 44b and the non-jointing regions 41a, 41b are not particularly limited, and any position can be selected. However, the central portion of the main surface of a battery cell typically deforms the most and is most likely to reach high temperatures. Therefore, when the heat transfer suppression sheet 50 is placed between the battery cells, it is preferable that there are no joining portions 55a, 55b in the region of the heat transfer suppression sheet 50 facing the central portion of the battery cell. That is, it is preferable that at least one of the facing regions 45a, 45b of the heat insulation material 10 and the elastic sheets 51a, 51b is not joined. Figure 1A The central region R0 shown is the non-jointed region 41a, 41b.

[0078] In this specification, as shown in the first embodiment, when the opposing regions 45a and 45b are rectangular, the central region R0 refers to the region whose center X is the intersection of the bisecting line L1 of one set of opposing sides and the bisecting line L2 of the other set. Specifically, region R0 can be defined such that the center X is located at the center of region R0. The area of ​​region R0 is preferably 10% or more of the area of ​​the entire opposing region 45a, more preferably 20% or more. When the opposing regions of the thermal insulation material and the elastic sheet are not rectangular, it is not necessary to strictly define the center X; the center X can be appropriately determined considering the shape of the opposing regions, and region R0 can be defined such that it includes the center X.

[0079] Next, taking the second embodiment as an example, the following description will be given of a heat transfer suppression sheet in which the heat insulation material is joined to the elastic sheet at a more preferred position.

[0080] [Second Implementation]

[0081] Figure 4A This is a top view showing the heat transfer suppression sheet according to the second embodiment of the present invention. Figure 4B yes Figure 4AA schematic cross-sectional view at line BB. Figure 4A and Figure 4B In the second embodiment shown, for the same as Figure 1A and Figure 1B The same components shown in the first embodiment are labeled with the same reference numerals, and their detailed descriptions are omitted or simplified.

[0082] In the heat transfer suppression sheet 53 according to the second embodiment, similarly to the first embodiment, the facing region 45a of the heat insulation material 10 and the elastic sheet 51a is rectangular, consisting of long sides 46a and 46b and short sides 48a and 48b. Specifically, the facing region 45a is formed by a set of opposing long sides 46a and 46b and a set of opposing short sides 48a and 48b orthogonal to these long sides 46a and 46b. Furthermore, a joint portion 55a is formed along the short side 48a at a position close to only one of the short sides 48a, thereby constituting a joint region 44a. Additionally, the region in the facing region 45a where no joint portion 55a is formed is a non-jointed region 41a.

[0083] Here, we will describe, for example, the case where the joint 55a is formed in two regions, near the short side 48a and the short side 48b surrounding the opposing region 45a. The specific elastic material constituting the elastic sheet will be described later. Generally, the elastic sheet is a component that expands and contracts significantly due to ambient temperature. Therefore, for example, when a heat transfer suppressing sheet is manufactured by joining a heat insulation material with an elastic sheet in a high-temperature environment, the elastic sheet may sometimes shrink when moved to a low-temperature environment. Conversely, when a heat transfer suppressing sheet manufactured in a low-temperature environment is moved to a high-temperature environment, the elastic sheet may sometimes elongate and bend. As a result, depending on the raw material of the heat insulation material, sometimes the heat insulation material may deform and generate strain, or the joint may peel off due to load, causing the elastic sheet to detach from the heat insulation material.

[0084] On the other hand, in the heat transfer suppression sheet 53 according to the second embodiment, a joint portion 55a for joining the heat insulation material 10 and the elastic sheet 51a is formed only in a portion of the area near the short side 48a, thereby constituting a joint region 44a. Therefore, as Figure 5 As shown, the non-joined region 41a extends from the boundary 34 between the joined region 44a and the non-joined region 41a to one end of the opposing region 45a. Furthermore, as indicated by arrow D1, at one end of the opposing region 45a, the thermal insulation material 10 and the elastic sheet 51a are configured to be separable. Therefore, even if the elastic sheet 51a expands or contracts after the thermal insulation material 10 and the elastic sheet 51a are joined, since the thermal insulation material 10 and the elastic sheet 51a are not fixed from the boundary 34 to the end of the opposing region 45a, deformation of the thermal insulation material 10 or peeling of the joint will not occur.

[0085] Thus, depending on the materials of the heat insulation material and the elastic sheet, as well as the environment during the manufacturing and handling of the heat transfer suppression sheet, the structure shown in the heat transfer suppression sheet 53 of the second embodiment described above is preferred.

[0086] Furthermore, in the heat transfer suppression sheet 53, the joining portion 55a is formed only in a region near the short side 48a, but the position of the joining portion 55a can be appropriately selected as needed. For example, the joining portion 55a can be formed along the long side 46a or long side 46b in a region near the long side 46a or long side 46b, or it can be formed in a region separated from the long sides 46a, 46b, and the short sides 48a, 48b. In this specification, the position near the edge or end refers to the position in contact with the edge or end or the position near it. In this embodiment, as described above, it is preferable to have a non-joining region 41a in the central part of the opposing region 45a; therefore, it is more preferable for the joining region 44a to be closer to the other end of the opposing region 45a opposite to the aforementioned end.

[0087] However, since the elastic sheet 51a expands and contracts due to temperature, the expansion and contraction is larger along the longer side of the opposing region 45a. Therefore, when the joint 55a is formed along the longer sides 46a and 46b, it is easy to apply a load to the joint 55a. Therefore, when the opposing region is rectangular, it is preferable to have the joint region 44a only near one of the short sides, and more preferably, the joint region 44a is formed extending along that short side. When the opposing region 45a is not rectangular but a polygonal region enclosed by three or more sides, similar to the rectangular case described above, it is preferable to form the joint region 44a only near one of the three or more sides. Furthermore, it is more preferable to form the joint region 44a along that single side.

[0088] Furthermore, the joint 55a need not be formed continuously within the joint region 44a. For example, multiple point joints can be formed, separated to a degree unaffected by the stretching and contraction of the elastic sheet.

[0089] [Third Implementation Method]

[0090] Figure 6 This is a schematic cross-sectional view illustrating a heat transfer suppression sheet according to a third embodiment of the present invention. Figure 6 In the third embodiment shown, for the relationship with Figure 4A and Figure 4B The same components shown in the second embodiment are labeled with the same reference numerals, and their detailed descriptions are omitted or simplified.

[0091] The heat transfer suppression sheet 54 of the third embodiment has a heat insulation material 10, an elastic sheet 51a laminated on the first surface 10a of the heat insulation material 10, and a joint portion 55a that joins them together. It also has a film 22 covering the outer surface of the laminate 19 containing the heat insulation material 10 and the elastic sheet 51a. The position of the joint region 44a, etc., is the same as in the second embodiment. Furthermore, in this embodiment, the elastic sheet 51a is formed to the same size as the heat insulation material 10.

[0092] In this heat transfer suppression sheet 54 configuration, since the outer peripheral surface of the laminate 19 is covered by the film 22, it is possible to prevent, for example, the inorganic particles constituting the insulation material 10 from falling off. Furthermore, when the film 22 is configured to fit tightly against the laminate 19, the insulation material 10 and the elastic sheet 51a can be more firmly secured. It should be noted that, in manufacturing the heat transfer suppression sheet 54 with the film 22, it is important to have a joint 55a during the process of covering the laminate 19 with the film 22 to prevent misalignment between the insulation material 10 and the elastic sheet 51a.

[0093] In the second and third embodiments described above, the heat transfer suppression sheets 53 and 54 are constructed by laminating elastic sheets 51a only on the first surface 10a of the heat insulation material 10, but the elastic sheets only need to be laminated on at least one surface of the heat insulation material 10. That is, as shown... Figure 1A and Figure 1B As shown, elastic sheets 51a and 51b can also be stacked on the first surface 10a and the second surface 10b of the thermal insulation material 10. Alternatively, the elastic sheet 51 can be sandwiched between a pair of thermal insulation materials 10, or the thermal insulation material 10 can be sandwiched between a pair of elastic sheets 51. Furthermore, various sheets other than the thermal insulation material 10 and the elastic sheet 51 can be stacked. There is no particular limitation on the relative dimensions of the thermal insulation material and the elastic sheet; the elastic sheets 51a and 51b can be smaller or larger than the thermal insulation material 10, and the thermal insulation material 10 and the elastic sheets 51a and 51b can also be of the same size.

[0094] [Manufacturing method of heat transfer inhibition sheet]

[0095] In this invention, the manufacturing method of the heat transfer inhibition sheet is not particularly limited. For example, the first embodiment is listed below as an example, using... Figure 1A and Figure 1BThe following explanation is provided. First, a heat-insulating material 10 and elastic sheets 51a and 51b made of the preferred materials described later are prepared. Next, bonding regions 44a and 44b and non-bonding regions 41a and 41b are formed in the heat-insulating material 10 or the elastic sheets 51a and 51b, and an adhesive is applied to the bonding regions 44a and 44b. Then, the elastic sheet 51a is laminated on the first surface 10a of the heat-insulating material 10, and the elastic sheet 51b is laminated on the second surface 10b, and the adhesive is dried while pressure is applied to them in the thickness direction. This allows the heat transfer suppression sheet 50 to be manufactured. Furthermore, for... Figure 2 The heat transfer suppression sheet 52 shown Figure 4A and Figure 4B The heat transfer suppression sheet 53 shown can also be manufactured using the same method. The manufacturing method of the insulation material will be described in detail later.

[0096] In addition, for Figure 6 The heat transfer suppression sheet 54 shown in the third embodiment can be manufactured in the same way as the heat transfer suppression sheet 50 described above, up to the step of bonding the heat insulation material 10 to the elastic sheet 51a. There are no particular limitations on the method of covering the outer peripheral surface of the laminate 19 with a film; an example of a method for shrink-packing the laminate 19 using a shrink film will be described below.

[0097] First, similar to the manufacturing method of the heat transfer suppression sheet 50, in Figure 6 In the shown joint 55a, a desired joining area 44a is selected to join the heat insulation material 10 with the elastic sheet 51a, and the two are joined to form a laminate 19. Next, the laminate 19 is placed on a planar membrane, and then the membrane is bent so that it also covers the upper surface of the laminate 19. Then, while pressing and heating the membrane on the lower and upper surfaces of the laminate 19 around the laminate 19, it is bonded together, thereby obtaining a laminate 19 enclosed in a membrane. Then, the laminate 19 enclosed in a membrane is placed on the conveyor belt of the shrinkage device and passes through the shrinkage tunnel of the hot air jet. As a result, the membrane undergoes thermal shrinkage and seals tightly against the outer peripheral surface of the laminate 19, thereby enabling the fabrication of a heat transfer suppression sheet 54.

[0098] Here, the direction in which the laminated body passes through the contraction tunnel is explained. For example... Figure 6As shown, when the joint 55a is formed near a short side 48a surrounding the opposing region 45b, the end face near the joint 55a is designated as the joint area side end face 49a, and the end face away from the joint 55a is designated as the non-joint area side end face 49b. If the laminate 19 enclosed in the membrane passes through the shrinkage tunnel with the non-joint area side end face 49b facing forward, the membrane shrinks from the non-joint area side end face 49b towards the joint area side end face 49a. At this time, the elastic sheet 51a shifts towards the joint area side end face 49a, and the elastic sheet 51a is fixed to the heat insulation material 10 by the shrinkage of the membrane. Simultaneously, the elastic sheet 51a in the heated area elongates. On the other hand, at the rear end, which is the non-joint area side end face 49b, since the elastic sheet 51a and the heat insulation material 10 are fixed by the joint 55a, the elastic sheet 51a is in a bent state and tightly adheres to the membrane at its central portion in the travel direction. Therefore, even if the elastic sheet 51a returns to its original size after cooling, it is not possible to achieve sufficient film adhesion, or the bending of the elastic sheet 51a may remain.

[0099] Therefore, when using a shrink-fit device to manufacture a heat transfer suppression sheet 54 having a membrane 22 covering its outer peripheral surface, it is preferable to have the joint area side end face 49a facing forward through the shrink-fit membrane tunnel. In this way, the membrane fixes the insulation material 10 from the side where it is joined to the elastic sheet 51a, while the insulation material 10 and the elastic sheet 51a can be separated at the non-joint area side end face 49b. Therefore, even if the elastic sheet 51a elongates, it can be prevented from being fixed in a bent state.

[0100] That is, when manufacturing the heat transfer suppressing sheet 54 using a shrink-fit device, it is preferable to use a laminate in which the joint portion 55a is formed in a portion of a region near either the short side 48a, 48b or the long side 46a, 46b. Furthermore, it is more preferable to use a laminate in which the joint portion 55a is formed in a portion of a region near either the short side 48a, 48b. Moreover, a structure in which the joint portion 55a is close to the adjacent side is particularly preferred. In either case, it is even more preferable that the joint portion 55a is formed along the adjacent side.

[0101] The following describes the components of the heat transfer suppression sheet of this embodiment. First, the heat insulation material will be described in detail.

[0102] [Insulation Materials]

[0103] As for the heat insulation material used in the heat transfer suppression sheet of this embodiment, there is no particular limitation as long as it has a heat insulation effect. Thermal conductivity can be cited as an indicator of heat insulation effect. In this embodiment, the thermal conductivity of the heat insulation material is preferably less than 1 (W / m·K), more preferably less than 0.5 (W / m·K), and even more preferably less than 0.2 (W / m·K). Furthermore, the thermal conductivity of the heat insulation material is more preferably less than 0.1 (W / m·K), more preferably less than 0.05 (W / m·K), and particularly preferably less than 0.02 (W / m·K).

[0104] It should be noted that the thermal conductivity of insulation materials can be determined according to the "Test Method for Thermal Conductivity of Refractory Materials" described in JIS R 2251.

[0105] In the heat transfer suppression sheet of the embodiments of the present invention, the heat insulation material only needs to contain inorganic particles, but for the purpose of improving the strength of the heat insulation material and preventing powder shedding, the heat insulation material may also contain organic fibers. Hereinafter, a structural example of a heat insulation material containing inorganic particles and organic fibers will be described in detail.

[0106] <Insulation Material (Structural Example S1)>

[0107] Figure 7 This is a photographic representation of an example S1 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 8 It is Figure 7 The accompanying photograph shows an enlarged view of a portion of the insulation material.

[0108] like Figure 7 and Figure 8 As shown, the thermal insulation material 10 comprises inorganic particles 4 and organic fibers 1. Furthermore, the thermal insulation 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 welded portion 5 covering at least a portion of its surface, and at least a portion of the inorganic particles 4 is welded to the surface of the organic fiber 1 through the welded portion 5. Thus, the surface of the organic fiber 1 is composed of inorganic particles 4.

[0109] In the heat insulation material 10 constructed in this way, due to the presence of multiple three-dimensionally interconnected pores 7, an air insulation effect can be achieved, thereby improving heat insulation performance. Furthermore, since the heat insulation material 10 contains highly flexible organic fibers 1, its flexibility is improved, and the organic fibers 1 easily intertwine with each other, resulting in increased sheet strength. Therefore, damage to the heat transfer suppression sheet with such heat insulation material 10 can be suppressed. Moreover, the presence of pores 7 in the heat insulation material 10 enhances the overall buffering capacity of the sheet. Therefore, when the battery cells 20a, 20b, and 20c expand during charging and discharging, the heat insulation material 10, together with the elastic sheet 51, absorbs the expansion of the battery cells, thereby further suppressing the degradation of battery cell performance.

[0110] Furthermore, in this embodiment, it is preferable that at least a portion of the aforementioned pores 7 are in communication with the surface of the thermal insulation material 10 and open to the outside. If the pores 7 are configured in this way, even if thermal runaway occurs in adjacent battery cells 20a, 20b, and 20c, and the thermal insulation material 10 reaches a high temperature causing the organic fibers 1 to decompose, the decomposition gases will not remain inside the sheet but can be released to the outside through the pores 7. Therefore, from this perspective, the effect of preventing sheet damage can also be achieved.

[0111] Furthermore, when the welded portion 5 on the outer peripheral surface of the organic fiber 1 fixes the inorganic particles 4 to the organic fiber 1, it can achieve the effect of suppressing the shedding (powdering) of the inorganic particles 4. Therefore, even when, for example, a portion of the battery cells 20a, 20b, and 20c expands and applies compressive stress or impact to the heat transfer suppression sheet 50, the effect of maintaining the shape of the heat insulation material 10 can be further improved, and the reduction in heat insulation effect caused by the compression deformation of the heat insulation material 10 can be prevented.

[0112] It should be noted that the welded portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, and there may be areas where the welded portion 5 is not present. In the thermal insulation material 10, the organic fiber 1 can be made of the core-sheath structure bonding fiber described later, but during the manufacturing process, when the sheath is peeled off, the organic fiber 1, which is the core, may be partially exposed. Even in this case, the effect of retaining the inorganic particles 4 can still be sufficiently achieved.

[0113] In this specification, the welded portion 5 refers to the part where the surface of the organic fiber 1 or the sheath of the bonding fiber with a core-sheath structure is temporarily melted by heating and then cooled and solidified again, which is formed in the manufacturing process of the insulation material 10 described later. The welded portion 5 is also the part where inorganic particles 4 are welded to the surface of the organic fiber 1 and where the organic fibers 1 are welded to each other. When the bonding fiber with a core-sheath structure is used as the material of the organic fiber 1, the welded portion 5 contains a second organic material constituting the sheath. In this embodiment, the inorganic particles 4 are welded to the surface of the organic fiber 1 through the welded portion 5, so the apparent fiber diameter of the organic fiber 1 becomes thicker, supporting the shape of the insulation material 10, thereby obtaining high strength.

[0114] Furthermore, the thermal insulation material 10 preferably contains inorganic fibers. The effects obtained by containing inorganic fibers will be explained in the following structural example S2 of the thermal insulation material.

[0115] <Insulation Material (Structural Example S2)>

[0116] Figure 9 This is a photographic representation of an example S2 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 9 In the structural example S2 shown, for the relationship with Figure 7 and Figure 8 The components shown in structural example S1 are labeled with the same reference numerals, and detailed descriptions are omitted. It should be noted that... Figure 9 The heat insulation material 40 shown can, for example, be used in place of the heat insulation material 10 in the heat transfer suppression sheets 50, 52, 53, and 54 described above.

[0117] like Figure 9 As shown, the thermal insulation material 40 includes inorganic fibers 15. Furthermore, a fiber layer 11 is formed on at least a portion of a first surface 40a orthogonal to its thickness direction and a second surface (not shown) of the thermal insulation material 40. The fiber layer 11 is a layered structure formed on the surfaces (first and second surfaces) of the thermal insulation material 40, where at least a portion of multiple organic fibers 1 are fused together via weld joints. That is, the fiber layer 11 is a layer formed by aggregating 10 or more organic fibers 1 on the surface of the thermal insulation material 40, extending in a strip-like manner, for example, along a direction substantially parallel to the surface.

[0118] Furthermore, a composite layer (not shown) is formed between the fiber layer 11 and the base layer 13 containing inorganic particles 4 and organic fibers 1, in which a portion of the fiber layer 11 and a portion of the inorganic particles 4 are mixed. Specifically, the composite layer is a region containing multiple organic fibers 1 that are at least partially fused together by welding portions and inorganic particles 4 fused to the organic fibers 1 by welding portions.

[0119] It should be noted that, in Figure 9 In the heat insulation material 40 shown, inorganic fibers 15 are contained in the base layer 13 containing inorganic particles 4 and organic fibers 1, but may also be contained in the fiber layer 11. Figure 9 Since the inorganic fibers 15 in the fiber layer 11 cannot be distinguished, they are not shown.

[0120] Furthermore, the thermal insulation material 40 has a fiber bundle 6 formed by fusing at least a portion of multiple organic fibers 1 together through a welding section 5. The fiber bundle 6 is formed by intertwining 10 or more organic fibers 1 and fusing a portion of the organic fibers 1 together, and is arranged in any direction in the thermal insulation material 40.

[0121] The heat insulation material 40 thus constructed contains inorganic fibers 15 that are not easily decomposed even at high temperatures. Therefore, for example, in the event of thermal runaway of the battery cell 20a and exposure of the heat transfer suppression sheet 50 disposed adjacent to the battery cell 20a to high temperatures, even if the organic fibers 1 in the heat insulation material 40 decompose, the inorganic fibers 15 will remain, thus reliably maintaining the shape of the heat insulation material 40. In addition, the flexible organic fibers 1 can easily wrap around the relatively stiff inorganic fibers 15, forming a three-dimensional skeleton from the inorganic fibers 15 and the organic fibers 1, thereby further improving the strength of the heat insulation material 40.

[0122] Furthermore, when the insulation material 40 has a fiber layer 11 on its surface and fiber bundles 6 inside, it can achieve higher strength compared to the case where the organic fibers 1 are dispersed. It should be noted that the fiber layer 11 is not only disposed on the base layer 13, but is a composite layer between the fiber layer 11 and the base layer 13, where a portion of the fiber layer 11 is mixed with a portion of the inorganic particles 4. Therefore, the fiber layer 11 is reliably constrained to the surface of the insulation material 40. Thus, the situation where only the fiber layer 11 detaches is not observed, and a high-strength insulation material 40 can be obtained. Moreover, since the elastic sheet 51 is laminated on the insulation material 40, the pressure applied to the base layer 13 can be further reduced.

[0123] Furthermore, when a fiber layer 11 is formed on the surface of the insulation material 40, the fiber layer 11 can absorb the impact applied to the insulation material 40. Therefore, even on the surface of the unlaminated elastic sheet 51, the inorganic particles contained in the insulation material 40 can be prevented from falling off.

[0124] <Insulation Material (Structural Example S3)>

[0125] Figure 10 This is a schematic diagram illustrating an example S3 of the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 11 It is Figure 10 A partially enlarged schematic diagram. Additionally, Figure 12 It is shown Figure 10 The attached diagram of the insulation material is a substitute photograph. Figures 10-12 In the structural example S3 shown, for the relationship with Figure 7 and Figure 8 The components shown in structural example S1 are labeled with the same reference numerals, and detailed descriptions are omitted. Additionally, Figures 10-12 The heat insulation material 60 shown can, for example, be used in place of the heat insulation material 10 in the heat transfer suppression sheets 50, 52, 53, and 54 described above.

[0126] like Figures 10-12 As shown, the heat insulation material 60 includes inorganic particles 4, organic fibers 1 made of a first organic material, and a welded portion 5 covering the outer peripheral surface of the organic fibers 1. As described above, the welded portion 5 includes a second organic material 17 having a melting point lower than that of the first organic material and the inorganic particles 4. Furthermore, in this embodiment, as the organic fiber, a core-sheath structure bonding fiber 3 having a core and a sheath covering the outer peripheral surface of the core is used, and the organic fiber 1 corresponds to the core. Additionally, the welded portion 5 is formed by temporarily melting the sheath of the bonding fiber 3 with the core-sheath structure due to heating and then cooling it. Furthermore, as... Figure 12 As shown, organic fibers 1 and welded portions 5 containing inorganic particles 4 constitute fiber portions 16, and a base material portion 18 containing inorganic particles is formed between multiple fiber portions 16. In addition, when the molten sheath portion is cooled, adjacent organic fibers 1 fuse together with each other at the contact portion 31 to form a three-dimensional skeleton.

[0127] In the heat insulation material 60 constructed in this way, the organic fibers 1 and the welded portions 5 function as a skeleton, thus achieving excellent strength and shape retention. Furthermore, the welded portions 5 covering the outer peripheral surface of the organic fibers 1, whether on the surface or center side of the heat insulation material 60, fix the inorganic particles 4 to the organic fibers 1, thereby suppressing dust shedding. Therefore, for example, by arranging the heat transfer suppression sheet 50 of this embodiment between multiple battery cells, excellent heat insulation performance can be maintained even when the battery cells expand and apply compressive stress or impact to the heat transfer suppression sheet 50.

[0128] The mechanism by which the aforementioned thermal insulation material 60 can suppress the shedding (powdering) of inorganic particles 4 is not yet clear, but one reason is believed to be that the organic fibers 1 and the welded portion 5 form a three-dimensional and robust skeleton, maintaining the shape of the thermal insulation material 60, thus suppressing deformation or compression of the thermal insulation material 60. Furthermore, since at least one of the first and second surfaces of the thermal insulation material 60 is laminated with an elastic sheet 51, the pressure applied to the thermal insulation material 60 can be reduced, which is also believed to help suppress the shedding of inorganic particles 4. Additionally, regardless of whether the surface of the thermal insulation material 60 has an elastic sheet 51, the fiber portion 16 exposed on the surface of the thermal insulation material 60 can absorb the impact applied to the thermal insulation material 60, which is also believed to be a reason why the inorganic particles 4 are retained.

[0129] like Figure 12 As shown, in the thermal insulation material 60, the welded portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, and the organic fiber 1 can be partially exposed. Since the thermal insulation material 60 uses the bonding fiber 3 with a core-sheath structure, the sheath may sometimes peel off during the manufacturing process of the thermal insulation material 60, but even when the organic fiber 1 is partially exposed, the effects of the present invention can be fully obtained.

[0130] <Insulation Material (Structural Example S4)>

[0131] Figure 13 This is a photographic representation of an example S4 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 14 It is Figure 13 The attached diagram shows an enlarged view of the structure of the insulation material. Figure 15 It is shown Figure 13 The attached diagram is a substitute photograph of the cross-section of the insulation material shown. Figures 13-15 In the structural example S4 shown, for the relationship with Figure 7 and Figure 8 The components shown in structural example S1 are labeled with the same reference numerals, and detailed descriptions are omitted. Additionally, Figures 13-15 The heat insulation material 70 shown can, for example, be used in place of the heat insulation material 10 in the heat transfer suppression sheets 50, 52, 53, and 54 described above.

[0132] like Figure 13 and Figure 14 As shown, the thermal insulation material 70 has a matrix 14 containing inorganic particles 4 and organic fibers 1 three-dimensionally oriented in the matrix 14. Furthermore, the organic fibers 1 have welded portions 5 covering at least a portion of their surface, and the organic fibers 1 are welded together through the welded portions 5. Similarly, the inorganic particles 4 are also welded to the surface of the organic fibers 1, thereby making the surface of the organic fibers 1 covered by the inorganic particles 4.

[0133] In addition, such as Figure 15As shown in the cross-sectional view, a plurality of pores 7 are formed in the matrix 14 of the thermal insulation material 70. Furthermore, in the matrix 14, at least a portion of the plurality of organic fibers 1 are interposed of each other. Figure 15 The fusion section 5 (not shown) is fused together to form a fiber bundle 6, and a gap 8 is formed between the multiple organic fibers 1 constituting the fiber bundle 6.

[0134] Furthermore, a fiber layer 11 is formed on at least a portion of a first surface 70a orthogonal to the thickness direction of the insulation material 70 and a second surface (not shown). The fiber layer 11 is a layered structure formed on the surfaces (first and second surfaces) of the insulation material 70, where at least a portion of multiple organic fibers 1 are fused together by a weld joint 5. Additionally, a composite layer 12 is formed between the fiber layer 11 and a base layer 13 containing a matrix 14 and organic fibers 1. The composite layer 12 is a layer in which a portion of the fiber layer 11 is mixed with a portion of the matrix 14. Specifically, the composite layer 12 is a region containing multiple organic fibers 1 fused together by a weld joint 5 and inorganic particles 4 fused to the organic fibers 1 by a weld joint 5.

[0135] Furthermore, the fiber bundle 6 is formed by intertwining 10 or more organic fibers 1 and fusing a portion of each organic fiber 1 together, and is arranged in any direction in the matrix 14 of the thermal insulation material 70. On the other hand, the fiber layer 11 is a layer formed by aggregating 10 or more organic fibers 1 on the surface of the thermal insulation material 70, and extends in a strip-like shape, for example, in a direction substantially parallel to the surface.

[0136] In the thermal insulation material 70 constructed in this way, the organic fibers 1 are three-dimensionally oriented to each other in the matrix 14, and the organic fibers 1 have welded portions 5 covering at least a portion of their surfaces. The welded portions 5 represent the areas where the surfaces of the organic fibers 1 are melted and then solidified again, and are formed during the manufacturing process of the thermal insulation material 70. In the thermal insulation material 70, the three-dimensionally oriented organic fibers 1 are welded to each other through the welded portions 5, so this structure acts as a skeleton to support the shape of the thermal insulation material 70, thereby achieving high strength.

[0137] Similarly, in the heat insulation material 70, the welded portion 5 on the outer peripheral surface of the organic fiber 1 also fixes the inorganic particles 4 to the organic fiber 1, thus achieving a higher powder shedding suppression effect. Therefore, even if, for example, a portion of the battery cells 20a, 20b, and 20c expands during charging and discharging, applying compressive stress or impact to the heat transfer suppression sheet 50, the shape of the heat insulation material 70 can be maintained. As a result, the shedding (powder shedding) of the inorganic particles 4 can be suppressed, and the reduction in heat insulation effect caused by the compression deformation of the heat insulation material 70 can be prevented.

[0138] In the thermal insulation material 70, the mechanism by which inorganic particles 4 are suppressed from falling off the sheet surface is considered to be the same as that of the thermal insulation material 60 in the above-described structural example S3.

[0139] It should be noted that in the thermal insulation material 70, the welded portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, and there may be areas without the welded portion 5. Even in this case, the effect of retaining the inorganic particles 4 can be sufficiently achieved.

[0140] In addition, since the thermal insulation material 70 contains organic fibers 1 with high flexibility, the flexibility of the thermal insulation material 70 can be improved, and the organic fibers 1 can easily wrap around each other, thereby improving the strength of the sheet.

[0141] Furthermore, in the thermal insulation material 70, since the matrix 14 has multiple pores 7 and there are gaps 8 between the multiple organic fibers 1 constituting the fiber bundle 6, the thermal insulation performance can be improved. Additionally, due to the presence of the gaps 8, the organic fibers 1 are less constrained by the matrix 14, thus further improving the flexibility and strength of the thermal insulation material 70. The gaps 8 do not need to be formed over the entire area between the multiple organic fibers 1; as long as the gaps 8 are formed in at least a portion between the organic fibers 1, the effect of suppressing heat transfer can be achieved.

[0142] Furthermore, since the insulation material 70 has fiber bundles 6 and fiber layers 11, it can achieve higher strength compared to the case where organic fibers 1 are dispersed. In addition, the fiber layers 11 are not only disposed on the base layer 13, but also exist as a composite layer 12 between the fiber layers 11 and the base layer 13, where a portion of the fiber layers 11 is mixed with a portion of the inorganic particles 4 constituting the matrix 14. Therefore, the fiber layers 11 are reliably constrained to the surface of the insulation material 70. Thus, a high-strength insulation material 70 can be obtained.

[0143] <Insulation Material (Structural Example S5)>

[0144] Figure 16 This is a schematic diagram illustrating an example S5 of the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 17 It is Figure 16 A magnified schematic diagram of part A of the insulation material shown. Figure 16 and Figure 17 In the structural example S5 shown, for the relationship with Figure 7 and Figure 8 The structural components of the insulation material shown in Example S1 are labeled with the same reference numerals, and detailed descriptions are omitted. Additionally, Figures 16-17 The heat insulation material 80 shown can, for example, be used in place of the heat insulation material 10 in the heat transfer suppression sheets 50, 52, 53, and 54 described above.

[0145] like Figure 16 and Figure 17 As shown, the thermal insulation material 80 has a matrix 14 containing inorganic particles 4, inorganic fibers 15 dispersed in the matrix 14, and organic fibers 1. Furthermore, the organic fibers 1 and inorganic fibers 15 are intertwined to form a three-dimensional network structure. It should be noted that in this embodiment, an air layer 28 is formed around a portion of the inorganic fibers 15. Additionally, a portion of the surface of the organic fibers 1 has a welded portion 5, through which at least a portion of the inorganic fibers 15 is welded to the organic fibers 1. Furthermore, at least a portion of the inorganic particles 4 is welded to the organic fibers 1 through the welded portion 5.

[0146] It should be noted that in this specification, the term "dispersed" for inorganic fiber 15 means that inorganic fiber 15 is not extremely agglomerated, but rather in a state of overall diffused configuration.

[0147] In the heat insulation material 80 constructed in this way, organic fibers 1 and inorganic fibers 15 are intertwined to form a three-dimensional network structure, which serves as a skeleton, thus achieving high strength. Therefore, even when the heat transfer suppression sheet 50 is compressed due to the expansion of the battery cells 20a, 20b, and 20c during charging and discharging, the shape of the heat insulation material 80 can be maintained. As a result, the shedding (powdering) of inorganic particles 4 can be suppressed, and the reduction in heat insulation effect caused by the compression deformation of the heat insulation material 80 can be prevented.

[0148] Furthermore, since the thermal insulation material 80 contains highly flexible organic fibers 1, its flexibility is improved, and the organic fibers 1 easily form a three-dimensional network structure when wound around the inorganic fibers 15, thus increasing its strength. Additionally, when the thermal insulation material 80 contains inorganic fibers 15, even in cases such as thermal runaway of the battery cell 20a or the thermal transfer suppression sheet adjacent to the battery cell 20a being exposed to high temperatures and causing the organic fibers 1 to decompose, the shape of the thermal transfer suppression sheet can be maintained. Therefore, by including highly flexible organic fibers 1 and inorganic fibers 15 that do not decompose even at high temperatures in the thermal insulation material 80, a thermal transfer suppression sheet that achieves a good balance between flexibility and strength can be obtained.

[0149] Furthermore, in this embodiment, an air layer 28 is provided around the inorganic fibers 15 dispersed in the matrix 14. The inorganic fibers 15 have a higher thermal conductivity than the organic fibers 1, but as described above, by forming an 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 during the manufacturing process of the insulation material 80, but it is not necessary to form the air layer 28 around the entire area of ​​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 effect of suppressing heat transfer can be obtained.

[0150] When the inorganic fibers 15 are uniformly dispersed in the matrix 14, the air layers 28 in the matrix 14 are also uniformly dispersed, so the thermal insulation material 80 can obtain uniform and high thermal insulation performance.

[0151] Furthermore, in the thermal insulation material 80, the organic fiber 1 has a welded portion 5 covering at least a portion of its surface. The welded portion 5 refers to the area where the surface of the organic fiber 1 is melted and then solidified again, and it is formed during the manufacturing process of the thermal insulation material 80. When at least a portion of the inorganic fiber 15 is fused to the organic fiber 1 through the welded portion 5, the intertwined organic fiber 1 and inorganic fiber 15 are fixed, thus obtaining a thermal insulation material 80 with higher strength.

[0152] Similarly, in this embodiment, the welded portion 5 on the outer peripheral surface of the organic fiber 1 also fixes the inorganic particles 4 to the organic fiber 1, thus achieving a higher powder shedding suppression effect. Therefore, even if, for example, a portion of the battery cells 20a, 20b, 20c expands and applies compressive stress or impact to the heat transfer suppression sheet, excellent heat insulation performance can be maintained.

[0153] In this embodiment, the mechanism for suppressing the detachment of inorganic particles 4 from the sheet surface is considered to be due to the formation of a three-dimensional and robust skeleton by fusing organic fibers 1 and inorganic fibers 15 through the welded portion 5, which maintains the shape of the heat insulation material 80 and thus suppresses the deformation or compression of the heat transfer suppression sheet. Furthermore, it is believed that regardless of whether the surface of the heat insulation material 80 has elastic sheets 51, when organic fibers 1 and inorganic fibers 15 are exposed on the surface of the heat insulation material 80, they can absorb the impact applied to the heat insulation material 80, thereby retaining the inorganic particles 4.

[0154] It should be noted that in the thermal insulation material 80, the welded portion 5 does not need to completely cover the outer peripheral surface of the organic fiber 1, and there can be areas without the welded portion 5. Even in this case, the effect of retaining the inorganic particles 4 can be sufficiently achieved.

[0155] <Insulation Material (Structural Example S6)>

[0156] Figure 18 This is a photographic representation of an example S6 illustrating the structure of the heat-insulating material used in the heat transfer suppression sheet according to an embodiment of the present invention. Figure 19 It is shown Figure 18 The accompanying photograph shows alternative images of other areas of the insulation material. Additionally, Figure 20 It is shown Figure 18 and Figure 19 The attached diagram is a substitute photograph of the cross-section of the insulation material shown. Figures 18-20 In the structural example S6 shown, for the relationship with Figures 13-15 The structural components of the insulation material shown in Example S4 are labeled with the same reference numerals, and detailed descriptions are omitted. Additionally, Figures 18-20 The heat insulation material 90 shown can, for example, be used in place of the heat insulation material 10 in the heat transfer suppression sheets 50, 52, 53, and 54 described above.

[0157] like Figure 18 As shown, the thermal insulation material 90 comprises inorganic particles 4 and organic fibers 1. Furthermore, at least a portion of the organic fibers 1 has a branched 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. A framework is formed by the base 32 and the plurality of branches 33.

[0158] In addition, Figure 19 In other regions of the insulation material 90 shown, organic fibers 1 with a branched structure consisting of a base 32 and branches 33 extending from the base 32 are also included. Additionally, Figure 19 The organic fiber 1 shown has a base 32 and branches 33 extending from the base 32 in five directions: direction D1, direction D2, direction D3, direction D4, and direction D5. The base 32 is thicker than the multiple branches 33.

[0159] In addition, such as Figure 18 and Figure 19 As shown, in this embodiment, inorganic particles 4 are fused to the surface of organic fiber 1, thereby making the surface of organic fiber 1 covered by inorganic particles 4.

[0160] In addition, such as Figure 20 As shown in the cross-sectional view, a plurality of pores 7 are formed in the thermal insulation material 90. Furthermore, in the thermal insulation material 90, at least a portion of multiple organic fibers 1 are fused together to form a fiber bundle 6, and voids 8 are formed between the multiple organic fibers 1 constituting the fiber bundle 6. Additionally, in... Figure 20 In this study, organic fibers 1 with a branched structure consisting of a base 32 and branches 33 extending in three directions from the base 32 were also identified.

[0161] Furthermore, a fiber layer 11 may be formed on at least a portion of the first and second surfaces orthogonal to the thickness direction of the insulation material 90. The fiber layer 11 is a layered structure formed on the surfaces (first and second surfaces) of the insulation material 90, where at least a portion of multiple organic fibers 1 are fused together. Additionally, a composite layer 12 may be formed between the fiber layer 11 and the base layer 13 containing 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 containing multiple fused organic fibers 1 and inorganic particles 4 fused to the organic fibers 1.

[0162] Furthermore, the fiber bundle 6 is formed by intertwining 10 or more organic fibers 1 and partially fusing them together, and is arranged in any direction inside the thermal insulation material 90. On the other hand, the fiber layer 11 is a layer formed by gathering 10 or more organic fibers 1 on the surface of the thermal insulation material 90, and extends in a strip-like shape along a direction substantially parallel to the surface.

[0163] In the thermal insulation material 90 constructed in this way, since at least a portion of the organic fiber 1 has a branched structure consisting of a base 32 and branches 33, the organic fiber 1 forms a skeleton that can maintain the shape of the thermal insulation material 90. In this embodiment, the base 32 is formed by fusing the organic fibers 1 together. Specifically, the base 32 is the part where a portion of multiple organic fibers 1 comes into contact, fuses together, and then solidifies, and is therefore thicker than the branches 33. Therefore, the base 32 can firmly support the overall skeleton, thereby significantly improving the strength of the thermal insulation material 90.

[0164] In the thermal insulation material 90, at least a portion of the organic fiber 1 has a branched structure consisting of a base 32 and branches 33 extending from the base 32 in at least three directions. The branched structure can be observed in cross-sectional photographs of the thermal insulation material 90, but a simpler method to confirm this is to observe a cross-section after tearing the thermal insulation material 90 along a plane orthogonal to its thickness direction. By observing this cross-section, the organic fiber 1 having the branched structure consisting of the base 32 and branches 33 extending from the base 32 in at least three directions can be easily confirmed. The base 32 and branches 33 will be described in detail below.

[0165] like Figure 21 and Figure 22As shown, the thermal insulation material 110 comprises inorganic particles 4 and organic fibers 1. On the surface of the thermal insulation material 110, a first region 42 containing strip-shaped fiber bundles composed of multiple organic fibers 1 and a second region 43 lacking fiber bundles 47 are formed. In this specification, the fiber bundle 47 is formed by intertwining 10 or more organic fibers 1, extending in a strip-like shape along a direction substantially parallel to the surface of the thermal insulation material 110.

[0166] That is, when observing the surface of the thermal insulation material 110, such as Figure 22 As shown, in the first region 42, a state in which multiple organic fibers 1 are intertwined is observed. On the other hand, in the second region 43, although there are also areas where several organic fibers 1 are observed, a fiber bundle 47 formed by multiple organic fibers 1 intertwining is not observed.

[0167] In addition, in this embodiment, the first region 42 and the second region 43 have an island structure, with the second region 43 being formed in such a way that it is surrounded by the first region 42, which is equivalent to the sea.

[0168] In the thermal insulation material 110, the fiber bundles 47 formed by the intertwining of organic fibers 1 exist in a strip-like manner along the surface of the thermal insulation material 110, thus improving the strength of the thermal insulation material 110. Furthermore, the entire surface is not covered by the fiber bundles 47, but includes a first region 42 where the fiber bundles 47 are present and a second region 43 where the fiber bundles 47 are absent, thus providing excellent flexibility for the thermal insulation material 110. Moreover, because the surface of the thermal insulation material 110 contains the aforementioned fiber bundles 47, even when impact or pressure is applied to the thermal insulation material 110, the fiber bundles 47 can absorb and mitigate the impact or pressure. Therefore, the shedding (dust shedding) of inorganic particles 4 can be suppressed, and the thermal insulation performance of the thermal insulation material 110 can be prevented from decreasing.

[0169] It should be noted that in the thermal insulation material 110, the organic fibers 1 and the fiber bundles 47 formed by the intertwining of the organic fibers 1 exist not only on the surface of the thermal insulation material 110, but also inside it. As a result, superior strength can be obtained.

[0170] The length of the fiber bundle 47, which extends along the surface of the insulation material 110, preferably reaches a certain length. Figure 23 An example of a method for specifying the length of a fiber bundle of 47 is illustrated.

[0171] like Figure 23As shown, rectangular imaginary frames 21 are arranged along strip-shaped fiber bundles 47 on the surface of the thermal insulation material 110. In this embodiment, the imaginary frames 21 are 5 mm square and are arranged continuously from one another. If there are fiber bundles 47 penetrating at least three consecutive imaginary frames 21, it can be determined that the fiber bundles 47 sufficiently enhance the strength of the thermal insulation material 110.

[0172] Alternatively, the length of the fiber bundle 47 extending in a strip shape can be easily measured. For example, a method can be used where a rope or the like is arranged along the fiber bundle 47 on the surface of the insulation material 110, and then the length of the rope is measured. When measuring the length of the continuous fiber bundle 47, if there is a fiber bundle 47 with a length of 20 mm or more, the effect of improving the strength of the insulation material 110 can be sufficiently obtained.

[0173] In addition, such as Figure 24 As shown, when the fiber bundles 47 of the insulation material 110 are connected into a mesh on its surface, the sheet strength can be further improved.

[0174] The above describes structural examples S1 to S7 of the thermal insulation material. However, the structure of the thermal insulation material is not limited to these examples, and thermal insulation materials with various structures can be used. Specifically, the thermal insulation materials of the above structural examples S1 to S7 have excellent thermal insulation effects and various properties such as suppressing dusting, further improving strength, and maintaining shape. Therefore, as shown in Figure 1... Figure 6 As shown, the heat transfer inhibition sheets 51a and 51b of elastic sheets are stacked on the above-mentioned heat insulation materials 10, 40, 60, 70, 80, 90, and 110 to achieve the above-mentioned effects and to prevent unnecessary pressure from being applied to the battery cells 20a, 20b, and 20c.

[0175] In addition, as mentioned above, the insulation material contains inorganic particles, and as other components, it may contain at least one selected from organic fibers, inorganic fibers, and organic particles. (See reference...) Figures 7 to 23 Explanation of each material.

[0176] <Inorganic Particles>

[0177] As the inorganic particle 4, a single inorganic particle can be used, or two or more inorganic particles can be used in combination. From the viewpoint of heat transfer suppression, particles composed of at least one inorganic material selected from oxide particles, carbide particles, nitride particles, and inorganic hydrate particles are preferred as the type of inorganic particle 4, with oxide particles being more preferred. Furthermore, there are no particular limitations on the shape; it is preferable to include at least one selected from nanoparticles, hollow particles, and porous particles. Specifically, inorganic microspheres such as silica nanoparticles, metal oxide particles, microporous particles, or hollow silica particles, particles composed of thermally expandable inorganic materials, and particles composed of hydrous porous bodies can also be used.

[0178] When the average secondary particle size of the inorganic particles is 0.01 μm or more, it is readily available, which can suppress the increase in manufacturing costs. Furthermore, when it is 200 μm or less, the desired heat 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, more preferably 0.05 μm or more and 100 μm or less.

[0179] Furthermore, when two or more inorganic particles 4 with different heat transfer inhibition effects are used together, multi-stage cooling of the heating element is possible, and endothermic effects can be exhibited over a wider temperature range. Specifically, it is preferable to use a mixture of large-diameter and small-diameter particles. For example, when nanoparticles are used as one type of inorganic particle, it is preferable to include inorganic particles composed of metal oxides as another type of inorganic particle. Hereinafter, small-diameter inorganic particles will be used as the first inorganic particle and large-diameter inorganic particles as the second inorganic particle, and the inorganic particles will be described in further detail.

[0180] <First Inorganic Particle>

[0181] (Oxide particles)

[0182] Oxide particles have a high refractive index, resulting in strong light diffuse reflection. Therefore, when oxide particles are used as the first inorganic particle, they can suppress radiative heat transfer, especially in high-temperature regions such as those experiencing abnormal heating. As oxide particles, at least one particle selected from silicon dioxide, titanium dioxide, zircon, barium titanate, zinc oxide, and aluminum oxide can be used. That is, only one of the aforementioned oxide particles that can be used as inorganic particles can be used, or two or more oxide particles can be used. In particular, silicon dioxide is a component with high thermal insulation properties, and titanium dioxide is a component with a high refractive index compared to other metal oxides. Both are highly effective at diffusely reflecting light and shielding radiative heat in high-temperature regions above 500°C. Therefore, silicon dioxide and titanium dioxide are most preferably used as oxide particles.

[0183] (Average primary particle size of oxide particles: greater than 0.001 μm and less than 50 μm)

[0184] The particle size of oxide particles can sometimes affect the reflection of radiant heat. Therefore, when the average primary particle size is limited to a specified range, higher thermal insulation can be achieved.

[0185] That is, when the average primary particle size of the oxide particles is greater than 0.001 μm, it is large enough compared to the wavelength of light that helps to heat up, so that the light is diffusely reflected efficiently. Therefore, in high-temperature regions above 500°C, the radiative heat transfer within the insulation material can be suppressed, and the insulation performance can be further improved.

[0186] On the other hand, when the average primary particle size of oxide particles is less than 50 μm, even when compressed, the number and number of contact points between particles do not increase, making it difficult to form a conductive heat transfer path. Therefore, it can reduce the impact on insulation performance in the normal temperature range where conductive heat transfer is dominant.

[0187] In addition, in this invention, the average primary particle size can be obtained by observing the particles under a microscope, comparing them with a standard scale, and taking the average value of any 10 particles.

[0188] (Nanoparticles)

[0189] In this invention, nanoparticles refer to spherical or near-spherical nanoparticles with an average primary particle size of less than 1 μm. Due to their low density, nanoparticles suppress conductive heat transfer. When nanoparticles are used as the first inorganic particle, the three-dimensionally linked pores 7 are further miniaturized, resulting in excellent thermal insulation properties that suppress convective heat transfer. Therefore, from the perspective of suppressing thermal conduction between adjacent nanoparticles when using the battery in a typical ambient temperature range, the use of nanoparticles is preferred.

[0190] Furthermore, when using nanoparticles with small average primary particle size as oxide particles, even when the thermal insulation material is compressed and its internal density increases due to expansion accompanying thermal runaway of the battery cells, the increase in conductive heat transfer of the thermal insulation material can still be suppressed. This is believed to be because nanoparticles easily form fine gaps between particles through electrostatic repulsion, resulting in low bulk density, thus allowing the particles to fill in a buffering manner.

[0191] It should be noted that in this invention, when using nanoparticles as the first inorganic particle, there are no particular limitations on their material as long as they meet the above definition of nanoparticles. For example, silica nanoparticles are not only highly insulating materials, but also, due to the small contact points between the particles, the heat conducted through silica nanoparticles is reduced compared to using larger silica particles. Furthermore, the bulk density of silica nanoparticles that can generally be obtained is 0.1 g / cm³. 3Therefore, even if the battery cells disposed on both sides of the heat insulation material undergo thermal expansion and exert large compressive stress on the heat insulation material, the size (area) and number of contact points between the silica nanoparticles will not increase significantly, thereby maintaining heat insulation performance. Therefore, silica nanoparticles are preferred as nanoparticles. Examples of silica nanoparticles include wet silica, dry silica, and aerogel; the silica nanoparticles particularly suitable for this embodiment will be described below.

[0192] Typically, wet-process silica is in a state of particle aggregation, while dry-process silica allows for particle dispersion. In the temperature range below 300°C, heat conduction is dominant; therefore, compared to wet-process silica, dry-process silica, which allows for particle dispersion, achieves superior thermal insulation performance. It should be noted that the thermal insulation materials shown in the above structural examples S1 to S7 are examples of thermal insulation materials manufactured using a dry process, but thermal insulation materials can also be manufactured using a wet process. However, to further improve thermal insulation, a manufacturing method that processes the mixture containing the materials into sheets using a dry process is preferred. Therefore, as inorganic particles, dry-process silica, silica aerogel, or the like with low thermal conductivity is preferred.

[0193] (Average primary particle size of nanoparticles: greater than 1 nm and less than 100 nm)

[0194] Higher thermal insulation can be achieved by limiting the average primary particle size of nanoparticles to a specified range.

[0195] That is, when the average primary particle size of the nanoparticles is greater than 1 nm and less than 100 nm, especially in the temperature range below 500 °C, it is possible to suppress convective and conductive heat transfer within the insulation material, thereby further improving the insulation performance. In addition, even under compressive stress, the voids remaining between the nanoparticles and the numerous contact points between the particles can also suppress conductive heat transfer, maintaining the insulation performance of the insulation material.

[0196] Furthermore, the average primary particle size of the nanoparticles is more preferably 2 nm or more, and even more 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 even more preferably 10 nm or less.

[0197] (Inorganic hydrate particles)

[0198] Inorganic hydrate particles undergo thermal decomposition when exposed to heat from a heating element and reaching temperatures above their thermal decomposition initiation temperature. This releases their contained water of crystallization, lowering the temperature of the heating element and its surroundings, thus exhibiting a so-called "endothermic effect." Furthermore, after releasing the water of crystallization, they become porous, exhibiting a thermal insulation effect through numerous air pores.

[0199] 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), and gallium hydroxide (Ga(OH)3).

[0200] For example, aluminum hydroxide contains approximately 35% water of crystallization, as shown in the following formula. Upon thermal decomposition, it releases this water of crystallization, exhibiting an endothermic effect. Furthermore, after releasing the water of crystallization, it transforms into a porous material called aluminum oxide (Al₂O₃), thus functioning as a thermal insulation material.

[0201] 2Al(OH)3→Al2O3+3H2O

[0202] Furthermore, in this embodiment, the heat transfer suppression sheet 50 is preferably located between battery cells, but in a battery cell experiencing thermal runaway, the temperature can rise sharply to over 200°C and continue to rise to around 700°C. Therefore, as inorganic particles, it is preferable to use inorganic hydrates with a thermal decomposition start temperature of 200°C or higher.

[0203] The thermal decomposition start 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. These temperatures largely overlap with the temperature range of a single battery cell that experiences rapid temperature rise during thermal runaway, effectively suppressing the temperature increase. Therefore, these inorganic hydrates can be considered preferred.

[0204] (Average secondary particle size of inorganic hydrate particles: greater than 0.01 μm and less than 200 μm)

[0205] Furthermore, when inorganic hydrate particles are used as the first inorganic particles, if their average particle size is too large, the first inorganic particles (inorganic hydrates) located near the center of the insulation material will require a certain amount of time to reach their thermal decomposition temperature. Therefore, the first inorganic particles near the center of the sheet may sometimes not completely decompose. Therefore, the average secondary particle size of the inorganic hydrate particles is preferably 0.01 μm or more and 200 μm or less, more preferably 0.05 μm or more and 100 μm or less.

[0206] (Particles composed of thermally expanding inorganic materials)

[0207] Examples of thermally expandable inorganic materials include vermiculite, bentonite, mica, and perlite.

[0208] (Particles composed of hydrous porous bodies)

[0209] Specific examples of hydrous porous materials include zeolite, kaolinite, montmorillonite, acid clay, diatomaceous earth, wet silica, dry silica, aerogel, mica, vermiculite, etc.

[0210] (Inorganic microspheres)

[0211] The thermal insulation material used in this invention may contain inorganic microspheres as the first inorganic particles.

[0212] When inorganic microspheres are included, in temperature ranges below 500°C, they can suppress convective or conductive heat transfer within the insulation material, thereby further improving the insulation performance of the insulation material.

[0213] As inorganic microspheres, at least one selected from white sand microspheres (Shirasu balloon), silica microspheres, fly ash microspheres, barite microspheres, and glass microspheres can be used.

[0214] (Inorganic microsphere content: less than 60% by mass relative to the total mass of the insulation material)

[0215] The content of inorganic microspheres is preferably 60% by mass or less relative to the total mass of the insulation material.

[0216] (Average particle size of inorganic microspheres: greater than 1 μm and less than 100 μm)

[0217] The average particle size of the inorganic microspheres is preferably 1 μm or more and 100 μm or less.

[0218] <Second Inorganic Particles>

[0219] When the thermal insulation material contains two types of inorganic particles, there are no particular limitations on the second inorganic particle as long as its material, particle size, etc., differ from the first inorganic particle. As the second inorganic particle, inorganic microspheres such as oxide particles, carbide particles, nitride particles, inorganic hydrate particles, silica nanoparticles, metal oxide particles, microporous particles, or hollow silica particles, particles composed of thermally expandable inorganic materials, or particles composed of hydrous porous bodies can be used, as detailed above.

[0220] It should be noted that nanoparticles have extremely low thermal conductivity and maintain excellent thermal insulation even when compressive stress is applied to the insulation material. Furthermore, metal oxide particles such as titanium dioxide are highly effective at shielding radiant heat. In addition, when using both large-diameter and small-diameter inorganic particles, the small-diameter particles intersect within the gaps between the large-diameter particles, thereby forming a denser structure and improving the heat transfer suppression effect. Therefore, for example, when using nanoparticles as the first inorganic particle, it is preferable to further include particles composed of metal oxides with a particle size larger than the first inorganic particles as the second inorganic particle in the insulation material.

[0221] Examples of metal oxides include silicon dioxide, titanium dioxide, aluminum oxide, barium titanate, zinc oxide, zircon, and zirconium oxide. In particular, titanium dioxide has a high refractive index compared to other metal oxides, and it is highly effective in diffusely reflecting light and shielding radiant heat in high-temperature regions above 500°C. Therefore, titanium dioxide is the preferred choice.

[0222] When using at least one particle selected from dry silica particles and silica aerogel as the first inorganic particle, and using at least one particle selected from titanium dioxide, zircon, zirconia, silicon carbide, zinc oxide, and alumina as the second inorganic particle, in order to obtain excellent thermal insulation performance in a temperature range below 300°C, the first inorganic particle preferably accounts for 50% or more of the total mass of the inorganic particles, more preferably 60% or more of the total mass, and even more preferably 70% or more of the total mass. Furthermore, the first inorganic particle preferably accounts for 95% or less of the total mass of the inorganic particles, more preferably 90% or less of the total mass, and even more preferably 80% or less of the total mass.

[0223] 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% or more by mass relative to the total mass of the inorganic particles, more preferably 10% or more by mass, and even more preferably 20% or more by mass. Furthermore, the second inorganic particles are preferably 50% or less by mass relative to the total mass of the inorganic particles, more preferably 40% or less by mass, and even more preferably 30% or less by mass.

[0224] (Average primary particle size of the second inorganic particle)

[0225] When the thermal insulation material contains second inorganic particles composed of metal oxides, if the average primary particle size of the second inorganic particles is 1 μm or more and 50 μm or less, radiative heat transfer can be effectively suppressed in high-temperature regions above 500°C. More preferably, the average primary particle size of the second inorganic particles is 5 μm or more and 30 μm or less, and most preferably, 10 μm or less.

[0226] (Content of inorganic particles)

[0227] In this embodiment, if the total content of inorganic particles 4 in the insulation material is properly controlled, the insulation performance of the insulation material can be fully ensured.

[0228] The total content of inorganic particles 4 is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total mass of the insulation material. Furthermore, if the total content of inorganic particles 4 is too high, the content of organic fibers will be 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 inorganic particles 4 is preferably 95% by mass or less, more preferably 90% by mass or less, relative to the total mass of the insulation material.

[0229] It should be noted that the content of inorganic particles 4 in the insulation material can be calculated, for example, by heating the insulation material at 800°C to decompose the organic components and then measuring the mass of the remaining part.

[0230] <Organic Fiber>

[0231] Organic fiber 1 imparts flexibility to the insulation material and maintains the strength and shape of the sheet by fusing inorganic particles 4 and other organic fibers 1 onto its surface. While single-component organic fibers can also be used as the material for organic fiber 1 in the insulation material, core-sheath structured bonding fibers are preferred. The core-sheath structured bonding fiber has a core extending along the length of the fiber and a sheath formed to cover the outer peripheral surface of the core. Furthermore, the core is composed of a first organic material, and the sheath is composed of a second organic material, the first organic material having a higher melting point than the second organic material. When using core-sheath structured bonding fibers as the material, in the aforementioned insulation material, the core corresponds to organic fiber 1. Additionally, during the manufacture of the insulation material, the second organic material constituting the sheath melts and then solidifies again; therefore, in the insulation material, the sheath becomes the welded portion 5.

[0232] (Organic fiber content)

[0233] In this embodiment, if the content of organic fiber 1 in the thermal insulation material is properly controlled, the reinforcement effect of the skeleton can be fully obtained.

[0234] The content of organic fiber 1 is preferably 2% by mass or more, more preferably 4% by mass or more, relative to the total mass of the insulation material. In addition, when the content of organic fiber 1 is too high, the content of inorganic particles 4 is relatively reduced. Therefore, in order to obtain the desired insulation performance, the content of organic fiber is preferably 10% by mass or less, more preferably 8% by mass or less, relative to the total mass of the insulation material.

[0235] (Fiber length of organic fibers)

[0236] There is no particular limitation on the fiber length of organic fiber 1. From the point of view of ensuring formability and processability, the average fiber length of organic fiber is preferably less than 10 mm.

[0237] On the other hand, from the viewpoint of enabling the organic fiber 1 to function as a skeleton and ensuring the compressive strength of the thermal insulation material, the average fiber length of the organic fiber 1 is preferably 0.5 mm or more.

[0238] (bonding fibers)

[0239] When using a core-sheath structure bonded fiber as the material of organic fiber 1, there are no particular limitations as long as the melting point of the core, i.e., the first organic material constituting organic fiber 1, is higher than that of the melting point of the sheath, i.e., the second organic material, which exists on the outer periphery of organic fiber 1. Bonded fibers 3 with the aforementioned core-sheath structure are generally commercially available, and the materials constituting the core and sheath can be the same or different from each other. Examples of bonded fibers where the core (first organic material) and sheath (second organic material) are the same material but have different melting points include bonded fibers where the core and sheath are made of polyethylene terephthalate, bonded fibers made of polypropylene, and bonded fibers made of nylon. Examples of bonded fibers where the core and sheath are made of different materials include bonded fibers where the core is made of polyethylene terephthalate and the sheath is made of polyethylene; and bonded fibers where the core is made of polypropylene and the sheath is made of polyethylene.

[0240] Furthermore, the melting point of the second organic material is preferably 90°C or higher, more preferably 100°C or higher. Additionally, the melting point of the second organic material is preferably 150°C or lower, more preferably 130°C or lower.

[0241] When the melting point of the first organic material constituting the core is sufficiently higher than that of the second organic material constituting the sheath, the temperature setting margin in the heating process can be expanded, and the temperature setting for obtaining the desired structure can be performed more easily. For example, it is preferable that the melting point of the first organic material is 60°C or more higher than that of the second organic material, more preferably 70°C or more higher, and even more preferably 80°C or more higher.

[0242] When using core-sheath structured bonding fibers as the insulation material, the core can be retained while the sheath melts during the heating process of the material mixture during insulation material manufacturing. Furthermore, after cooling, the outer periphery of the core (organic fiber 1) is coated with a second organic material containing inorganic particles 4, thus retaining the inorganic particles 4. The organic fiber 1 with the fused inorganic particles 4 has a coarser fiber diameter, therefore its strength is higher than that of a material composed solely of organic fibers 1. Moreover, since the bonding fibers in the mixture exist in an irregular orientation, the organic fibers 1 fuse together in areas where they contact each other, forming a three-dimensional skeleton. As a result, the overall shape of the insulation material can be maintained with higher strength.

[0243] It should be noted that even when using organic fibers without a core-sheath structure as bonding fibers, by setting the temperature, it is possible to retain the central portion of the organic fibers while only melting the surface, thereby allowing inorganic particles to be coated onto the surface or for the organic fibers to fuse together. However, in the manufacture of thermal insulation materials, heating is usually performed from one or both sides orthogonal to the thickness direction. Due to the use of materials with high thermal insulation performance, strict temperature management is required to raise the surface side of the sheet and the central side in the thickness direction to the same temperature.

[0244] In contrast, when using bonding fibers with a core-sheath structure where the melting point of the first organic material constituting the core is higher than that of the second organic material constituting the sheath, it is extremely easy to set the temperature for retaining the core while melting the sheath. As a result, the obtained insulation material has an ideal structure on both the surface and center sides, where the organic fibers 1 are fused together to form a skeleton that maintains the sheet strength, and a welded portion 5 containing inorganic particles 4 is formed on the surface of the organic fibers 1. Therefore, the aforementioned bonding fibers with a core-sheath structure are preferably used as the material for insulation.

[0245] In this embodiment, the melting point of the second organic material constituting the sheath of the bonding fiber 3 represents the melting temperature at which the second organic material begins to melt and deform, but softening accompanied by shape change is also judged as a type of melting and deformation. The melting point of the sheath of the bonding fiber can be determined, for example, by the following method.

[0246] The bonding fiber, which is the object of the test, is placed in contact with glass fiber, which has a higher melting point. It is heated from room temperature to, for example, 200°C at a heating rate of 5°C / min, and then cooled to room temperature. If the surface of the bonding fiber melts and deforms and fuses with the glass fiber at the point of contact, or if the cross-sectional shape of the bonding fiber changes, it can be determined that the melting point of the second organic material constituting the sheath is below 200°C. In this embodiment, by varying the heating temperature and observing the fusion state of the bonding fiber and glass fiber or the cross-sectional shape of the bonding fiber after cooling using the above method, the melting point of the second organic material constituting the sheath can be determined.

[0247] (Content of bonding fibers)

[0248] In this embodiment, when using the core-sheath structure of the bonding fiber 3 as the material, if the content of the bonding fiber in the mixture is properly controlled, the skeleton reinforcement effect in the resulting thermal insulation material can be fully obtained.

[0249] The content of the bonding 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, when the content of the bonding fiber 3 is too high, the content of the inorganic particles 4 is relatively reduced. Therefore, in order to obtain the desired thermal insulation performance, the content of the bonding fiber 3 is preferably 25% by mass or less, more preferably 20% by mass or less, relative to the total mass of the mixture.

[0250] <Inorganic Fibers>

[0251] As inorganic fiber 15, a single inorganic fiber can be used, or two or more inorganic fibers can be used in combination. Examples of inorganic fibers include silica fiber, alumina fiber, aluminosilicate 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-based fibers, glass fiber, glass wool, slag wool and other glass-based fibers, as well as mineral-based fibers such as rock wool, basalt fiber, wollastonite, mullite fiber and others.

[0252] These inorganic fibers are preferred in terms of heat resistance, strength, and availability. From an operational point of view, silica-alumina fibers, alumina fibers, silica fibers, rock wool, alkaline earth silicate fibers, and glass fibers are particularly preferred among inorganic fibers.

[0253] There are no particular limitations on the cross-sectional shape of inorganic fibers; examples include circular cross-sections, flat cross-sections, hollow cross-sections, polygonal cross-sections, and core-shaped cross-sections. Among these, fibers with irregular cross-sections such as hollow, flat, or polygonal cross-sections can slightly improve thermal insulation and are therefore preferred.

[0254] The preferred lower limit for the average fiber length of inorganic fibers is 0.1 mm, and a more preferred lower limit is 0.5 mm. On the other hand, the preferred upper limit for the average fiber length of inorganic fibers is 50 mm, and a more preferred upper limit is 10 mm. When the average fiber length of inorganic fibers is less than 0.1 mm, it is difficult for the inorganic fibers to entangle with each other, and the mechanical strength of the insulation material may decrease. On the other hand, when it exceeds 50 mm, although a reinforcing effect can be obtained, the inorganic fibers cannot be tightly entangled with each other, or they are only curled from single inorganic fibers, which easily creates continuous gaps, and may therefore lead to a decrease in insulation performance.

[0255] The preferred lower limit for the average fiber diameter of inorganic fibers is 1 μm, a more preferred lower limit is 2 μm, and a further preferred lower limit is 3 μm. Conversely, the preferred upper limit for the average fiber diameter of inorganic fibers is 15 μm, and a more preferred upper limit is 10 μm. When the average fiber diameter of inorganic fibers is less than 1 μm, the mechanical strength of the inorganic fibers themselves may decrease. Furthermore, from the viewpoint of impact on human health, the average fiber diameter of inorganic fibers is preferably 3 μm or more. On the other hand, when the average fiber diameter of inorganic fibers is greater than 15 μm, the solid-state heat transfer using inorganic fibers as a medium increases, which may lead to a decrease in thermal insulation performance. Additionally, the formability and strength of the insulation material may deteriorate.

[0256] (Inorganic fiber content)

[0257] In this embodiment, when the thermal insulation material contains inorganic fibers, the content of inorganic fibers is preferably 3% by mass or more and 15% by mass or less relative to the total mass of the thermal insulation material.

[0258] Furthermore, the content of inorganic fibers relative to the total mass of the insulation material is more preferably 5% by mass and less than 10% by mass. By setting this content, the shape retention, pressure resistance, wind pressure resistance, and inorganic particle retention capabilities provided by the inorganic fibers can be evenly manifested. In addition, by appropriately controlling the content of inorganic fibers, the organic fibers 1 and inorganic fibers intertwine to form a three-dimensional network, thereby further improving the effect of retaining the inorganic particles 4 and other compounded materials described later.

[0259] <Hot Melt Powder>

[0260] In this embodiment, the material used as the thermal insulation material, in addition to the organic fibers 1 and inorganic particles 4 described above, may also contain hot-melt powder as a binder. The hot-melt powder is, for example, a powder containing a third organic material different from the first and second organic materials described above, and having the property of melting upon heating. By including the hot-melt powder in the mixture during the manufacture of the thermal insulation material and heating it, the hot-melt powder melts and then solidifies while containing the surrounding inorganic particles 4 upon cooling. Therefore, it is possible to further suppress the inorganic particles 4 from detaching from the thermal insulation material.

[0261] As a hot-melt powder, various hot-melt powders with different melting points can be cited. Considering the melting points of the core and sheath of the bonding fiber used, a hot-melt powder with an appropriate melting point can be selected. Specifically, as long as the melting point of the third organic material constituting the hot-melt powder is lower than the melting point of the first organic material constituting the aforementioned organic fiber, the heating temperature used to retain the core while melting the sheath and the hot-melt powder can be set. For example, when the melting point of the hot-melt powder is below the melting point of the sheath, the heating temperature during manufacturing can be set between the melting points of the core and the sheath, thus making it easier to set the heating temperature.

[0262] On the other hand, the type of hot-melt powder used can also be selected so that its melting point is between that of the core and the sheath. When using a hot-melt powder with such a melting point, after both the sheath and the hot-melt powder melt and are then cooled and solidified, the hot-melt powder existing in the gaps between the organic fiber (core) 1, the surrounding molten sheath, and the inorganic particles 4 solidifies first. As a result, the position of the organic fiber 1 can be fixed, and then the molten sheath fuses with the organic fiber, thereby easily forming a three-dimensional skeleton. Therefore, the strength of the entire sheet can be further improved.

[0263] When the melting point of the third organic material constituting the hot-melt powder is sufficiently lower than that 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 the desired structure can be more easily performed. For example, it is preferable that the melting point of the first organic material is 60°C or more higher than that of the third organic material, more preferably 70°C or more higher, and even more preferably 80°C or more higher.

[0264] Furthermore, the melting point of the hot-melt powder (third organic material) is preferably 80°C or higher, more preferably 90°C or higher. Additionally, the melting point of the hot-melt powder (third organic material) is preferably 180°C or lower, more preferably 150°C or lower. Examples of components constituting the hot-melt powder include polyethylene, polyester, polyamide, and ethylene-vinyl acetate.

[0265] (Content of hot melt powder)

[0266] When a mixture contains hot-melt powder to suppress the shedding of inorganic particles, even a trace amount can achieve the effect of suppressing powder shedding. Therefore, the content of hot-melt powder relative to the total mass of the mixture is preferably 0.5% by mass or more, and more preferably 1% by mass or more.

[0267] On the other hand, if the content of hot melt powder is increased, the content of inorganic particles 4 and the like will be relatively reduced. Therefore, in order to obtain the desired heat insulation performance, the content of 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.

[0268] <Other Blended Materials>

[0269] In addition, the insulation material may contain binders, colorants, etc., as needed. These components all contribute to enhancing the insulation material and improving its formability, and are preferably less than 10% by mass relative to the total mass of the insulation material.

[0270] <Manufacturing Methods of Thermal Insulation Materials>

[0271] Regarding the manufacturing method of thermal insulation materials, the manufacturing method of the thermal insulation material in structural example S2 will be described in detail below.

[0272] For example, a mixture is prepared by feeding bonding fibers (not shown), inorganic particles 4 and inorganic fibers 15 with a core-sheath structure into a mixer such as a V-type mixer in a specified ratio.

[0273] It should be noted that, as described above, the preferred bonding fiber is a fiber with a core-sheath structure having a core made of a first organic material and a sheath 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.

[0274] The resulting mixture is then placed into a pre-designed mold, pressurized using a stamping press, and the resulting molded body is heated, thereby melting the sheath of the bonding fibers. The heated molded body is then cooled, and the molten second organic material constituting the sheath and the inorganic particles 4 surrounding the bonding fibers fuse to the core (organic fiber 1). Simultaneously, the bonding fibers also fuse to each other in the contact areas. This yields a sheet-like thermal insulation material 40.

[0275] In addition, the thermal insulation material 10 without inorganic fibers 15 can also be obtained by the same manufacturing method as the thermal insulation material 40 described above, and the use of inorganic fibers 15 can be arbitrarily selected.

[0276] Furthermore, when the aforementioned heat insulation materials are mixed and then pressurized and heated, the intertwined organic fibers 1 exposed on the surface are heated, forming a fiber layer 11 on the surface of the heat insulation material 40. The resulting fiber layer 11 has the effect of increasing the strength of the heat insulation material 40 and mitigating the impact on the surface of the heat insulation material 40.

[0277] (Heating conditions)

[0278] When using a core-sheath structure of bonding fiber as the insulation material, the heating temperature in the heating process is preferably higher than the melting point of the second organic material constituting the sheath and lower than the melting point of the first organic material constituting the core. By setting the heating temperature to such a level, as described above, the strength of the sheet can be ensured by the core on either the surface side or the center side of the sheet, and the inorganic particles 4 can be retained by the welded portion 5.

[0279] Specifically, the heating temperature in the heating process is preferably set to be at least 10°C higher than the melting point of the second organic material constituting the sheath, and more preferably at least 20°C higher. On the other hand, the heating temperature is preferably set to be at least 10°C lower than the melting point of the first organic material constituting the core, and more preferably at least 20°C lower.

[0280] There is no particular limitation on the heating time, but it is preferable to set a heating time that allows the sheath to melt sufficiently. For example, it can be set to a time of 3 minutes or more but less than 15 minutes.

[0281] When the material includes hot-melt powder as the heat-insulating material, the heating temperature in the heating process is preferably set to be at least 10°C higher than the higher 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, more preferably at least 20°C higher. On the other hand, the heating temperature is preferably set to be at least 10°C lower than the melting point of the first organic material constituting the core, more preferably at least 20°C lower. By setting the heating temperature to such a level, a strong skeleton can be formed, the strength of the sheet can be further improved, and the detachment of inorganic particles 4 can be prevented by the welded portion 5, etc.

[0282] As described above, thermal insulation materials can be manufactured using either a dry or wet process, with the dry process being preferred. When using the dry process, inorganic particles 4 suitable for dry processing are used, and solvents such as water, which are required for wet molding, are not added to the mixture. However, during the manufacture of the thermal insulation material, to prevent the inorganic particles 4 and other powders from scattering and making raw material handling difficult, a small amount of solvent such as water can be added within the dry process range. 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.

[0283] [Elastic sheet]

[0284] The elastic sheets 51a and 51b used in the heat transfer suppression sheets 50, 52, 53, and 54 of the first to fourth embodiments are formed by processing an elastic material into a sheet shape. Known materials can be used as the elastic material. Specifically, sheets formed from rubber or thermoplastic elastomers that have elasticity that allows them to deform flexibly with the deformation of the battery cells 20a, 20b, and 20c can be used.

[0285] Rubber can be either synthetic rubber or natural rubber. Examples of synthetic rubber include styrene-butadiene rubber, butadiene rubber, chloroprene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, nitrile rubber, silicone rubber, fluororubber, acrylic rubber, polyurethane rubber, polysulfide rubber, epichlorohydrin rubber, and foamed silicone rubber.

[0286] Examples of thermoplastic elastomers include various thermoplastic elastomers based on polystyrene, polyolefins, vinyl chloride, polyurethane, polyester, polyamide, and polybutadiene. Furthermore, the elastomer can be either porous or non-porous. It should be noted that in the case of a porous elastomer, the bubble structure can be either independent bubble type or interconnected bubble type.

[0287] (Dimensions of the elastic sheet)

[0288] The thickness of the elastic sheet is not particularly limited, but to effectively obtain the effect of the elastic sheet, it is preferably 1 mm or more and 10 mm or less.

[0289] [Joint]

[0290] In the above embodiments, the joint is formed by drying the adhesive, but in this invention, the structure of the joint is not limited to this. Regarding the means of joining the insulation material and the elastic sheet, in addition to chemical bonding methods such as adhesives, joining components such as sutures, sewing machines, and label pins can also be used (physical bonding methods). When using sutures, sewing machines, label pins, etc., the insulation material and the elastic sheet can be joined at one point or at multiple closely spaced points. When forming the joint with an adhesive, the type of adhesive is not particularly limited; commonly used adhesives can be used, but flame-retardant adhesives are preferred. Specifically, as a flame-retardant inorganic adhesive, for example, a heat-curing heat-resistant inorganic adhesive whose main components are refractory ceramics such as alumina and inorganic polymers can be used. As a flame-retardant organic adhesive, for example, an adhesive containing halogen-based, phosphorus-based, organosilicon-based, or nitrogen-based flame-retardant materials can be used. Furthermore, using both the above-mentioned flame-retardant inorganic adhesives and flame-retardant organic adhesives is also effective.

[0291] [membrane]

[0292] As shown in the fourth embodiment above, the outer peripheral surface of the laminate of the thermal insulation material and the elastic sheet can also be covered with a membrane or the like. Examples of polymer membranes include those composed of polyimide, polycarbonate, polyethylene terephthalate (PET), polyphenylene sulfide, polyetherimide, cross-linked polyethylene, flame-retardant chloroprene rubber, polyvinylidene fluoride, rigid vinyl chloride, polybutylene terephthalate, polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane (PFA), fluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), rigid polyvinyl chloride (PCV), flame-retardant PET, nylon, acrylic acid, epoxy resin, polyurethane, polyetheretherketone, polycarbonate, aromatic polyamide, polystyrene, polyethersulfone, polyamide-imide, polyacrylonitrile, polyethylene, polypropylene, and polyamide.

[0293] When the entire surface of a laminate is covered with a film, shrink packaging is preferred. Therefore, it is preferable to use a film containing a material suitable for shrink packaging. Examples of such materials include polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and vinyl chloride.

[0294] It should be noted that when using a shrink-fit device to cover the surface with a film, as shown in the fourth embodiment described above, it is preferable to use a heat transfer suppression sheet 54 with a joint portion 55a formed at a position near one end face (joint area side end face 49a) of the laminate 19, extending along the end face 49a. Furthermore, when covering the outer peripheral surface of the laminate with a film, methods such as bonding the films together using adhesives, wrapping the insulation material and elastic sheet 51 with a film and bonding a portion thereof, and storing the insulation material and elastic sheet 51 in a bag-like film are examples.

[0295] (Membrane thickness)

[0296] The membrane adheres tightly to the outer surface of the laminate to prevent the shedding of particles, etc., and also prevents the insulation material from shifting from the elastic sheet; therefore, an appropriate thickness is preferred. Furthermore, in order to form a configuration in which the membrane is at least partially adhered to the shape of the laminate, the membrane preferably has appropriate flexibility. If the membrane thickness exceeds 1 mm, it becomes difficult to follow the shape of the laminate, and the membrane may crack or break. Therefore, the membrane thickness is preferably 1 mm or less, more preferably 0.1 mm or less, and even more preferably 0.05 mm or less.

[0297] On the other hand, there is no particular limitation on the lower limit of the film thickness. In order to prevent easy breakage due to friction with battery cells and the like and to obtain the desired strength, it is preferably 0.005 mm or more, and more preferably 0.01 mm or more.

[0298] (Other materials contained in the membrane)

[0299] Furthermore, the membrane is required to be resistant to the high temperatures of the battery cells 20a, 20b, and 20c, therefore, it is preferably flame-retardant. Specifically, it is preferable to include inorganic materials or flame-retardant materials. Examples of other materials included in the membrane include, as inorganic materials, talc, calcium carbonate, aluminum hydroxide, titanium dioxide, vermiculite, zeolite, synthetic silica, zirconium oxide, zircon, barium titanate, zinc oxide, and aluminum oxide; and as flame-retardant materials, examples include bromine-based flame retardants, chlorine-based flame retardants, phosphorus-based flame retardants, boron-based flame retardants, organosilicon-based flame retardants, and nitrogen-containing compounds.

[0300] <Thickness of the heat transfer inhibition sheet>

[0301] The thickness of the heat transfer suppression sheet in this embodiment is not particularly limited, but is preferably 0.05 mm or more and 10 mm or less. When the thickness is 0.05 mm or more, sufficient compressive strength can be obtained. On the other hand, when the thickness is 10 mm or less, the heat transfer suppression sheet can obtain good thermal insulation properties.

[0302] [Battery Pack]

[0303] Examples of battery packs using the heat transfer suppression sheet 50 of various embodiments of the present invention are as described above. Figure 3 As shown. Here, using Figure 3 The composition and performance of the battery pack are explained in detail. Furthermore, as mentioned above, Figure 3 The heat transfer suppressing sheet 50 shown can be replaced not only with heat transfer suppressing sheets 52, 53, and 54 having other structures, but also with heat transfer suppressing sheets having other structures within the scope of this invention. Furthermore, the heat insulation material 10 can be replaced not only with heat insulation materials having the various structures described above, but also with other heat insulation materials within the scope of this invention.

[0304] like Figure 3 As shown, the battery pack 100 has a plurality of battery cells 20a, 20b, 20c and a heat transfer suppression sheet 50 according to this embodiment, the plurality of battery cells being connected in series or in parallel. For example, the heat transfer suppression sheet 50 of this embodiment is located between battery cells 20a and 20b, and between battery cells 20b and 20c. Furthermore, the battery cells 20a, 20b, 20c and the heat transfer suppression sheet 50 are housed in the battery casing 30.

[0305] In addition, regarding the heat transfer inhibition sheet 50, as described above.

[0306] In this battery pack 100, because the heat transfer suppression sheet has high thermal insulation properties, even if a battery cell 20a reaches a high temperature, the heat transfer suppression sheet 50, which has a heat transfer suppression effect, exists between it and the battery cell 20b, thus suppressing the propagation of heat to the battery cell 20b. Furthermore, because the heat transfer suppression sheet in this embodiment has an elastic element, it can prevent unnecessary stress from being applied to the battery cells during charging / discharging or in abnormal situations. As a result, it can suppress the degradation of battery performance and improve durability.

[0307] It should be noted that the battery pack 100 in this embodiment is not limited to... Figure 3 The illustrated battery pack. For example, the heat transfer suppression sheet 50 can be disposed not only between battery cells 20a and 20b, and between battery cells 20b and 20c, but also between battery cells 20a, 20b, and 20c and the battery casing 30, or attached to the inner surface of the battery casing 30.

[0308] In this battery pack 100 configuration, in the event of a fire in a single battery cell, the spread of flames to the outside of the battery casing 30 can be suppressed. For example, the battery pack 100 of this embodiment is sometimes used in electric vehicles (EVs) and is installed under the passenger's floor. In this case, even if a single battery cell catches fire, the safety of the passenger can be ensured.

[0309] In addition, since the heat transfer suppression sheet 50 can be placed not only between each battery cell, but also between the battery cells 20a, 20b, 20c and the battery casing 30, there is no need to manufacture new fireproof materials, etc., and a safe battery pack 100 can be easily and cost-effectively constructed.

[0310] In the battery pack of this embodiment, the heat transfer suppression sheet 50 disposed between the battery cells 20a, 20b, and 20c and the battery casing 30 can be in contact with the battery cells or may have a gap. Since the heat transfer suppression sheet 50 is an elastic sheet, deformation of the battery cells can be allowed even if the temperature of any one of the battery cells rises and its volume expands. Furthermore, in this embodiment, the heat transfer suppression sheet connects the heat insulation material and the elastic sheet through a joint, so even with a gap, they will not shift relative to each other, and the effect of allowing battery cell deformation by the elastic sheet can be fully obtained. In addition, since there is a non-jointed area without a joint between the heat insulation material and the elastic sheet, the reduction in heat insulation between battery cells can be suppressed.

[0311] It should be noted that the heat transfer suppression sheet of this embodiment can be manufactured into various shapes using its manufacturing method. Therefore, it is not affected by the shape of the battery cells 20a, 20b, 20c and the battery casing 30, and can be adapted to any shape. Specifically, in addition to prismatic batteries, it can also be applied to cylindrical batteries, flat batteries, etc.

[0312] Various embodiments have been described above with reference to the accompanying drawings, but the present invention is not limited to these examples. It should be understood that various modifications or alterations will be readily apparent to those skilled in the art within the scope of the claims, and these modifications also fall within the technical scope of the present invention. Furthermore, the constituent elements of the above embodiments can be combined arbitrarily without departing from the spirit of the invention.

[0313] Furthermore, this application is based on Japanese Patent Application No. 2024-028786, filed on February 28, 2024, the contents of which are incorporated herein by reference.

[0314] Explanation of reference numerals in the attached figures

[0315] 1. Organic Fiber

[0316] 3. Bonding fibers

[0317] 4 Inorganic particles

[0318] 5. Welded section

[0319] 6, 47 fiber bundles

[0320] Thermal insulation materials in sizes 10, 40, 60, 70, 80, 90, and 110.

[0321] 11. Fiber layer

[0322] 14 Matrix

[0323] 15 Inorganic Fibers

[0324] 19-layer stack

[0325] 20a, 20b, and 20c battery cells

[0326] 22 membranes

[0327] 30 Battery casing

[0328] 32 Base

[0329] 33rd Branch

[0330] 41a, 41b Non-jointed regions

[0331] 42 First District

[0332] 43 Second Region

[0333] 44a, 44b joint area

[0334] 45a and 45b opposite regions

[0335] 46a, 46b Long side

[0336] 48a, 48b Short sides

[0337] 49a Joint area side end face

[0338] 49b Non-jointed area side face

[0339] 50, 52, 53, 54 Heat transfer inhibitors

[0340] 51, 51a, 51b elastic sheets

[0341] 55a and 55b joint

[0342] 100 battery pack.

Claims

1. A heat transfer suppression sheet comprising: a heat-insulating material containing inorganic particles; an elastic sheet laminated on at least one of a first surface and a second surface orthogonal to the thickness direction of the heat-insulating material; and a joint for joining the heat-insulating material and the elastic sheet, characterized in that, The opposing regions of the thermal insulation material and the elastic sheet include a jointed region where the joint exists and a non-jointed region where the joint does not exist.

2. The heat transfer suppression sheet according to claim 1, characterized in that, The non-jointing region is located in the central part of the opposing regions.

3. The heat transfer suppression sheet according to claim 1, characterized in that, The engagement region is located near the end of the opposing region.

4. The heat transfer suppression sheet according to claim 1, characterized in that, The opposing region is a region enclosed by three or more sides, and the joining region is only located near one of the three or more sides.

5. The heat transfer suppression sheet according to claim 4, characterized in that, The joining area is formed to extend along one of the edges.

6. The heat transfer suppression sheet according to claim 1, characterized in that, The opposing region is a rectangular area enclosed by a set of long sides and a set of short sides orthogonal to the long sides, and the joining region is only located near one of the short sides.

7. The heat transfer suppression sheet according to claim 6, characterized in that, The joining area is formed to extend along the short side.

8. The heat transfer suppression sheet according to claim 1, characterized in that, The joint is formed only in a portion of the opposing regions to constitute the joint area. The non-jointed region extends from the boundary between the joined region and the non-jointed region to one end of the opposing region, where at one end of the opposing region, the thermal insulation material and the elastic sheet are configured to be separable.

9. The heat transfer suppression sheet according to claim 8, characterized in that, The joint is formed at a position near the other end opposite to one end of the opposing region.

10. The heat transfer suppression sheet according to claim 1, characterized in that, The joint is made of an adhesive that bonds the thermal insulation material to the elastic sheet.

11. The heat transfer suppression sheet according to claim 1, characterized in that, The joint is formed by a joining member that joins the thermal insulation material to the elastic sheet.

12. The heat transfer suppression sheet according to claim 1, characterized in that, The elastic sheet comprises at least one selected from synthetic rubber, natural rubber, and thermoplastic elastomers.

13. The heat transfer suppression sheet according to claim 1, characterized in that, The insulation material also contains organic fibers.

14. The heat transfer inhibiting sheet according to any one of claims 1 to 13, characterized in that, A membrane having a coating covering the outer peripheral surface of a laminate containing the insulating material and the elastic sheet.

15. A battery pack having a plurality of battery cells and a heat transfer suppressor sheet according to any one of claims 1 to 13, wherein the plurality of battery cells are connected in series or in parallel.

16. A battery pack having a plurality of battery cells and a heat transfer suppressor as described in claim 14, wherein the plurality of battery cells are connected in series or in parallel.

Images