Fireproof sheet and method for manufacturing the same, and battery pack

Abstract

Provided is a fireproof sheet, a manufacturing method thereof, and a battery pack. The fireproof sheet can further suppress the spread of heat between battery cells even in an abnormal state, is excellent in resistance to external forces such as bending and twisting, and can be easily manufactured. A fireproof sheet (1) is formed by stacking a fireproof member (10) and an elastic member (20), and the engaging surface (40) of the fireproof member (10) that engages with the elastic member (20) and the engaging surface (40) of the elastic member (20) that engages with the fireproof member (10) are engaged by a resin-made clip (50) or a resin-made needle (60) in a manner that allows movement along the plane in which the engaging surfaces (40) are located. In addition, a battery pack (100) has a plurality of battery cells (110), a battery case (120) that houses the battery cells (110), and the above-described fireproof sheet (1).

Description

Technical Field

[0001] The present invention relates to fireproof sheets for battery packs used in, for example, power tools, vehicles, etc., and methods for manufacturing the same, as well as battery packs housed in power tools, vehicles, etc. and used as power sources for electric motors, etc. Background Technology

[0002] Generally speaking, among power tools, some are connected to so-called commercial power supplies for use, while others have a battery pack inside that serves as the power source for the electric motor. From the point of view, such as superior operability, most power tools use those with an internal battery pack.

[0003] A battery pack is composed of multiple battery cells connected in series or in parallel. For example, the battery cells are housed in a battery casing made of polycarbonate or the like to form a single unit, which is then housed inside a power tool.

[0004] As battery cells housed within power tools, lithium-ion rechargeable batteries, which offer higher capacity and output compared to lead-acid and nickel-metal hydride batteries, are primarily used. However, in cases of thermal runaway occurring within a single battery cell due to internal short circuits, overcharging, or other abnormal conditions (i.e., "abnormal situations"), heat can propagate to adjacent battery cells, potentially causing thermal runaway in those cells.

[0005] Furthermore, in recent years, from an environmental protection perspective, the development of electric vehicles or hybrid vehicles powered by electric motors has become increasingly popular. 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 motor. In such battery cells used in vehicles, high-capacity and high-output lithium-ion secondary batteries are primarily used. Similar to the battery cells housed in power tools, these cells are susceptible to thermal runaway.

[0006] As a countermeasure against thermal runaway as described above, Patent Document 1, for example, proposes a battery pack that can prevent or suppress the spread of heat to adjacent battery cells when abnormal heating occurs due to overcurrent flowing into a battery cell. The battery pack described in Patent Document 1 consists of multiple battery cells and a block made of metal material that holds the battery cells; this block is composed of multiple small blocks. Furthermore, the size of the gap between the block and the battery cells is adjusted.

[0007] According to the battery pack described in Patent Document 1, which is constructed in this way, the battery cell blocks are made of metallic material, thus enabling rapid heat dissipation.

[0008] Furthermore, Patent Document 2 discloses a battery pack designed to improve the heat dissipation of secondary batteries and mitigate performance degradation. The battery pack described in Patent Document 2 is constructed by housing multiple secondary batteries within a casing, and a rubber sheet with a plate shape that has a thermal conductivity exceeding a specified value and changes shape according to pressure is disposed between the multiple secondary batteries and the casing.

[0009] According to Patent Document 2, the following is described: Because the rubber sheet has a high thermal conductivity, it can effectively dissipate heat from the secondary battery through the casing. Furthermore, because the rubber sheet is elastic, the battery pack can be protected from damage during drops.

[0010] Furthermore, laminates of heat insulation components and elastic components are also known. For example, Patent Document 3 describes a heat insulation component for batteries obtained by laminating a heat insulation component and a buffer portion such as an elastic molded body and making them integral.

[0011] Existing technical documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2014-96271

[0013] Patent Document 2: Japanese Patent Application Publication No. 2004-146161

[0014] Patent Document 3: Japanese Patent Application Publication No. 2021-140968 Summary of the Invention

[0015] The technical problem that the invention aims to solve

[0016] In addition, if a battery cell experiences thermal runaway, gas will be generated inside the battery, causing the internal pressure to rise and deform the battery cell. In cases of large deformation, the casing may be damaged.

[0017] Such deformation of the battery cells also occurs slightly when the battery cells forming the battery pack are charged and discharged in cycles (i.e., under "normal use" conditions). During charging and discharging, the internal pressure of the battery cells is repeatedly increased and decreased. The battery cells are repeatedly pressed and relaxed based on the casing, which is a cause of battery performance degradation.

[0018] Regarding the battery pack in the aforementioned patent document 1, the battery cell blocks are made of metallic materials, which allows for rapid heat dissipation, but does not take into account the damage to the battery casing and the reduction in battery performance caused by deformation of the battery cells.

[0019] Furthermore, the battery pack described in Patent Document 1 requires multiple blocks. Additionally, to vary the gap between the blocks and battery cells, the block design needs to be tailored to the electronic devices, power tools, etc., that carry the battery pack. Therefore, the design of the blocks complicates the assembly of the battery pack.

[0020] Furthermore, in the battery pack described in Patent Document 2, the suppression of thermal runaway of adjacent battery cells is not considered in the event of thermal runaway of a battery cell.

[0021] Furthermore, in the battery heat insulation component described in Patent Document 3, the heat insulation part and the buffer part are joined using an adhesive or rivets. When an adhesive is used, both the adhesive and the adhesive layer need to be coated. Additionally, the adhesive strength may decrease due to insufficient coating or deterioration from repeated charging and discharging. Furthermore, the adhesive may peel off when subjected to external forces such as bending or torsion.

[0022] On the other hand, when using rivets, the rivets are made entirely of metal, which may compromise the electrical insulation between the units. Furthermore, because they lack flexibility, the mating surfaces where the heat insulation part joins the buffer part, and vice versa, are difficult to move along the surfaces where they meet, making it difficult to withstand external forces such as bending and torsion. Additionally, movement in the thickness direction of the battery heat insulation component is also difficult, hindering the full utilization of the deformation and elasticity of the buffer part.

[0023] The present invention was made in view of the above-mentioned technical problems, and its object is to provide a fireproof sheet that can further suppress the heat transmission between battery cells not only under normal conditions but also under abnormal conditions, and has excellent resistance to external forces such as bending and torsion, and can be easily manufactured.

[0024] Means for solving technical problems

[0025] The above-mentioned objective of the present invention is achieved by the structure of the fireproof sheet as described below [1].

[0026] [1] A fireproof sheet,

[0027] The fireproof sheet is composed of layers of fireproof components and elastic parts, and,

[0028] The engagement surface of the fireproof component that engages with the elastic member and the engagement surface of the elastic member that engages with the fireproof component are engaged in a manner that allows them to move along the surface where the engagement surface is located.

[0029] Furthermore, preferred embodiments of the fireproof sheet of the present invention relate to the following [2] to

[10] .

[0030] [2] In the fireproof sheet of [1], the characteristic is that,

[0031] The fireproof component and the elastic component are joined by at least one of the following joining components: resin clips and resin needles.

[0032] [3] In the fireproof sheet of [2], the characteristic is that,

[0033] The joining components are arranged such that the distribution density on the outer periphery of the surface of the fireproof sheet is higher than the distribution density on the central portion of the surface of the fireproof sheet.

[0034] [4] In any one of [1] to [3], the fireproof sheet is characterized in that,

[0035] The elastic component is formed of rubber or an elastomer.

[0036] [5] In any one of [1] to [4], the fireproof sheet is characterized in that,

[0037] The fireproof component contains at least one of inorganic particles, organic fibers, and inorganic fibers.

[0038] [6] In the fireproof sheet of [5], the characteristic is that,

[0039] The inorganic particles are particles composed of at least one type of inorganic material selected from oxide particles, carbide particles, nitride particles and inorganic hydrate particles.

[0040] [7] In any one of [1] to [6], the fireproof sheet is characterized in that,

[0041] The fireproof component has at least one first inorganic fiber and a second inorganic fiber with different properties selected from average fiber diameter, shape and glass transition temperature.

[0042] [8] In the fireproof sheet of [7], the characteristic is that,

[0043] The average fiber diameter of the first inorganic fiber is greater than the average fiber diameter of the second inorganic fiber.

[0044] The first inorganic fiber is linear or needle-like, and the second inorganic fiber is dendritic or crimped.

[0045] [9] In the fireproof sheet of [7], the characteristic is that,

[0046] The first inorganic fiber is an amorphous fiber.

[0047] The second inorganic fiber is at least one type of fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber.

[0048] The average fiber diameter of the first inorganic fiber is greater than the average fiber diameter of the second inorganic fiber.

[0049]

[10] In the fireproof sheet of [7], the characteristic is that,

[0050] The fireproof component contains inorganic particles, which include at least one type selected from nanoparticles, hollow particles, and porous particles.

[0051] The first inorganic fiber is an amorphous fiber.

[0052] The second inorganic fiber is at least one inorganic fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber.

[0053] Furthermore, the above-mentioned objective of the present invention is achieved by the following

[11] configuration involved in the manufacturing method of the fireproof sheet.

[0054]

[11] A method for manufacturing a fireproof sheet, wherein the fireproof sheet is any one of [1] to

[10] , and in the manufacturing method,

[0055] The fireproof component and the elastic component are joined in such a way that the joint surface of the fireproof component engaging with the elastic component and the joint surface of the elastic component engaging with the fireproof component can move along the surface where the joint surface is located.

[0056] Furthermore, the preferred embodiments of the present invention relating to the method of manufacturing the fireproof sheet are as follows

[12] .

[0057]

[12] A method for manufacturing the fireproof sheet of

[11] , characterized in that,

[0058] The fireproof component is joined to the elastic member using at least one of resin-made rivets and resin-made needles.

[0059] Furthermore, the above-mentioned objective of the present invention is achieved by the structure of the battery pack described below

[13] .

[0060]

[13] A battery pack having:

[0061] Multiple battery cells; a battery housing that houses the battery cells; and a fireproof sheet of any one of [1] to

[10] .

[0062] Invention Effects

[0063] The fireproof sheet of the present invention is a structure formed by stacking fireproof components and elastic components. When the fireproof sheet is disposed between battery cells, the elastic components improve the sealing between the fireproof components and the battery cells. Therefore, it can further suppress the heat transmission between battery cells not only under normal conditions but also under abnormal conditions.

[0064] Furthermore, the fire-resistant components and elastic parts are joined without adhesives, using resin clips or needles. The clips or needles are made of resin and are flexible, allowing the fire-resistant components and elastic parts to move along their joint surface. Deformation in the thickness direction of the fire-resistant sheet is also easy, enabling it to readily adapt to bending, torsion, and other external forces, while maintaining the elastic force in the thickness direction based on the elastic parts. Moreover, compared to the use of adhesives, manufacturing is simpler, requiring only a clip-binding machine and a nail gun.

[0065] In addition, the battery pack of the present invention contains battery cells and the aforementioned fireproof sheet, so it can suppress the heat propagation between battery cells not only under normal conditions but also under abnormal conditions, and can prevent the chain reaction of thermal runaway. Attached Figure Description

[0066] Figure 1 This is a cross-sectional view showing Embodiment 1 of the fireproof sheet of the present invention (using resin-made clips).

[0067] Figures 2A to 2D yes Figure 1 The top view of the fireproof sheet shown is an example of the distribution of resin clips.

[0068] Figure 3 It is imitation Figure 1 A cross-sectional view showing a variation of embodiment 1.

[0069] Figure 4 It is imitation Figure 1 A cross-sectional view showing another variation of embodiment 1.

[0070] Figure 5 It is imitation Figure 1 This is a cross-sectional view showing Embodiment 2 of the fireproof sheet of the present invention (using a resin needle).

[0071] Figure 6 This is a schematic cross-sectional view of the fireproof component containing two types of inorganic particles according to the present invention.

[0072] Figure 7 This is a cross-sectional view showing an embodiment of the battery pack of the present invention, and a perspective view showing an example of the shape.

[0073] Label Explanation

[0074] 1: Fireproof sheet;

[0075] 10: Fireproof components;

[0076] 11: First inorganic particle;

[0077] 12: Second inorganic particles;

[0078] 15: First inorganic fiber;

[0079] 16: Second inorganic fiber;

[0080] 18: Organic fibers;

[0081] 19: Connecting components;

[0082] 20: Elastic components;

[0083] 40: Joint surface;

[0084] 50: Resin-made clips;

[0085] 60: Resin-made threading needle;

[0086] 100: Battery pack;

[0087] 110: Battery cell;

[0088] 120: Battery casing. Detailed Implementation

[0089] The inventors of this invention have conducted in-depth research on fireproof sheets that can suppress heat propagation between battery cells not only under normal conditions but also under abnormal conditions, and that exhibit excellent resistance to external forces such as bending and torsion.

[0090] As a result, the inventors of this invention discovered that by layering fireproof components and elastic components, and without using adhesives or metal rivets, but instead using resin clips or resin needles, the two components can be joined in such a way that the joint surface of the fireproof component and the elastic component can move along the surface where the joint surface is located. This solves the aforementioned technical problem.

[0091] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, 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.

[0092] First, the fireproof sheet according to the embodiments of the present invention will be described.

[0093] [Fireproof sheet]

[0094] Figure 1 This is a cross-sectional view showing an example of the fireproof sheet according to this embodiment. The fireproof sheet 1 is, for example, as described below. Figure 7 Therefore, arranged between the battery cells 110, in order to make the fireproof member 10 contact with the adjacent battery cells 110, 110 on both sides, as shown in the figure, it is preferable to use a stacked structure in which a pair of fireproof members 10, 10 clamp the elastic member 20. If the fireproof sheet 1 is compressed in the thickness direction and inserted between the battery cells 110, 110, the fireproof members 10, 10 on both surfaces are pressed outward in the thickness direction by the elastic member 20, thereby improving the tightness with the battery cells 110, 110.

[0095] Even during normal use charge-discharge cycles, the battery cell 110 will deform slightly. When the battery cell 110 expands, it is subjected to pressure from other adjacent battery cells 110, but the elastic member 20 deforms and absorbs the deformation of the other adjacent battery cells 110, thus suppressing the degradation of battery performance.

[0096] Furthermore, even if one battery cell 110 experiences thermal runaway during an abnormal event, the fireproof member 10 can suppress the propagation of heat to adjacent battery cells 110. To suppress heat transfer, the fireproof member 10 of the fireproof sheet 1 is effectively sealed to the battery cell 110 by means of the elastic member 20. Moreover, since the battery cell 110 deforms significantly during an abnormal event, the elastic member 20 can absorb the deformation to suppress the deformation of adjacent battery cells 110.

[0097] The fireproof sheet 1 of this embodiment has the effects of fireproof component 10 and elastic component 20 as described above. However, in this embodiment, instead of using adhesive, resin clips or resin needles are used to join the two together.

[0098] Next, Embodiment 1 of the fireproof sheet of the present invention will be described.

[0099] (Implementation Method 1)

[0100] <Resin Clips>

[0101] Figure 1 This is a cross-sectional view of the fireproof sheet 1 in Embodiment 1, where resin-made clips 50 are used as the connecting parts.

[0102] The resin-made clip 50 is flexible, and its foot 50a can freely flex along the joint surface 40 of the fireproof member 10 and the elastic member 20, i.e., in the left-right direction shown in the figure. Therefore, in their joined state, the fireproof member 10 and the elastic member 20 can move in a sliding manner along the joint surface 40. Thus, even if external forces such as bending or torsion are applied to the fireproof sheet 1, it will not peel off at the joint surface 40 as would occur if adhesive were used.

[0103] In addition, metal rivets are difficult to bend along the joint surface at 40 degrees, and therefore, like adhesives, they are not good at handling bending and torsion.

[0104] Furthermore, the foot 50a of the resin-made clip 50 can be bent and flexed in the thickness direction of the fireproof sheet 1, i.e., the vertical direction shown in the figure. Therefore, it is also possible to maintain the compression of the fireproof sheet 1 in the thickness direction when it is inserted between the battery cells 110, 110, and the elastic force of the fireproof sheet 1 in the thickness direction after insertion based on the elastic member 20. In addition, gaps may appear between the crown 50b and the bent portion 50c of the resin-made clip 50 and the fireproof sheet 1 (in this case, the fireproof member 10), but since the crown 50b and the bent portion 50c are both made of resin and are flexible, stress can be mitigated when the fireproof sheet 1 expands.

[0105] Furthermore, metal rivets are difficult to bend in the thickness direction of the fireproof sheet 1, so such an effect cannot be obtained.

[0106] Furthermore, the resin clip 50 is made of an electrically insulating material, thus ensuring sufficient electrical insulation when connected to the battery unit 110.

[0107] Furthermore, since rivets are made of metal, they cannot achieve the same level of electrical insulation.

[0108] Resin-made fasteners 50 are distributed at specified intervals across the entire surface of the fireproof sheet 1. For example, as shown... Figure 2A As shown, when viewed from the upper surface of the fireproof sheet 1, it can be distributed in a staggered, alternating pattern, or as shown in the image. Figure 2B As shown, they are distributed symmetrically from top to bottom.

[0109] In addition, when the fireproof sheet 1 is disposed between the battery cells 110, a high compressive force is applied to the central part of the sheet, so it is easy to deviate along the joint surface 40 between the fireproof member 10 and the elastic member 20.

[0110] Therefore, as Figure 2C and Figure 2D As shown, it is preferable that the resin fasteners 50 are arranged with a higher distribution density on the outer periphery compared to the central portion of the surface of the fireproof sheet 1 (the circular portion shown by the dashed line in the figure). In this case, it is also preferable that the resin fasteners 50 are arranged radially around the central portion of the surface of the fireproof sheet 1 (the circular portion shown by the dashed line in the figure).

[0111] In addition, such as Figure 3 As shown, the foot 50a of the resin clip 50 can also be inserted into a fireproof member 10 (upper side in the figure), and after passing through the elastic member 20, the end of the foot 50a can be fixed to a suitable part of another fireproof member 10 (lower side in the figure).

[0112] Thus, the fireproof components 10, 10 and the elastic member 20 are maintained in a connected state, and as Figure 1 As shown, the bent portion 50c of the resin-made clip 50 is not exposed, and the entire surface of the fireproof sheet 1 is only the fireproof component 10, thus improving the overall flame retardancy.

[0113] And, as Figure 4 As shown, the crown 50b of the resin-made clip 50 can also be embedded in the surface 10a of the fireproof component 10.

[0114] Therefore, the resin clip 50 will not be in contact with the battery unit 110, thus preventing the resin clip 50 from burning or disappearing even if the battery unit 110 experiences thermal runaway.

[0115] Furthermore, the joining method based on the resin-made clip 50 is not limited to the above and various modifications can be made. For example, in the above description, the insertion direction of the foot 50a of the resin-made clip 50 is inserted from one side of the fireproof member 10 (the upper side in the example shown in the figure). Although the figure is omitted, the foot 50a can also be inserted alternately from the other side of the fireproof member 10 (the lower side in the figure).

[0116] In this case, the crown 50b alternately exists on the surfaces of the upper and lower fireproof members 10, 10, thereby achieving uniform bonding strength on the whole sheet. Even if the resin clips 50 burn or disappear during thermal runaway, it can effectively prevent thermal runaway from chaining to adjacent battery cells 110.

[0117] Next, Embodiment 2 of the fireproof sheet of the present invention will be described.

[0118] (Implementation Method 2)

[0119] <Resin Needle>

[0120] Figure 5 It is imitation Figure 1 This is a cross-sectional view showing Embodiment 2 of the fireproof sheet of the present invention (using a resin-made needle). Figure 5 As shown, a resin pin 60 can also be used as the joining unit instead of the resin pin 50. The resin pin 60 is continuous with a resin wire and is roughly "I" shaped, extending outwards in two directions from both ends.

[0121] In the resin-made needle 60, the foot 60a can also bend along the surface where the mating surface 40 is located in the left-right direction in the figure, and bend along the thickness of the fireproof sheet 1 in the up-down direction in the figure, so as to achieve the same effect as the resin-made rivet 50.

[0122] In addition, such as Figure 2C , Figure 2DAs shown, the distribution density of the resin needle 60 on the outer periphery of the fireproof sheet 1 is also higher than that on the central part of the fireproof sheet 1.

[0123] Since only resin-made clips 50 and resin-made needles 60 are used for joining, there is no need for a coating process like adhesives, and the manufacturing of fireproof sheet 1 is also simple.

[0124] Next, the fireproof components and elastic parts constituting the fireproof sheet of the present invention will be described in detail.

[0125] <Fireproof components and elastic elements>

[0126] There are no restrictions on the fireproof component 10 and the elastic component 20. The preferred composite materials will be described below.

[0127] [Fireproof components]

[0128] The fire-resistant component 10 preferably contains at least one of organic fibers and inorganic fibers, and more preferably contains inorganic particles if necessary. In this embodiment, materials that have been processed into, for example, sheet form can be used. It is important that the materials constituting the fire-resistant component 10 have thermal insulation properties; therefore, materials with high thermal insulation performance are selected.

[0129] Thermal conductivity can be listed as an indicator of thermal insulation performance. In this embodiment, the thermal conductivity of the fireproof component 10 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 fireproof component 10 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.

[0130] In addition, thermal conductivity can be determined according to the "Test Method for Thermal Conductivity of Refractory Materials" as described in JIS R 2251.

[0131] (Inorganic particles)

[0132] The inorganic particles are preferably composed of heat-resistant compounds. Single-material inorganic particles or combinations of two or more materials can be used. Using two or more inorganic particles with different heat transfer inhibition effects allows for multi-stage cooling of the heat-generating element and enables heat absorption over a wider temperature range, thus improving thermal insulation performance. In cases containing two or more inorganic particles, the preferred materials, shapes, and particle sizes of each inorganic particle are described below.

[0133] Figure 6This is a schematic cross-sectional view of a fire-resistant component 10 containing two types of inorganic particles. As an example, the fire-resistant component 10 shown in the figure includes, in addition to the first inorganic particles 11 and the second inorganic particles 12, two types of inorganic fibers (first inorganic fiber 15 and second inorganic fiber 16), organic fibers 18, and a binding material 19, as described later.

[0134] From the viewpoint of suppressing heat transfer, particles composed of at least one inorganic material selected from oxide particles, carbide particles, nitride particles, and inorganic hydrate particles are preferred as the first inorganic particle 11 and the second inorganic particle 12. Oxide particles are more preferred. Alternatively, inorganic hollow spheres such as silica nanoparticles, metal oxide particles, microporous particles, and hollow silica particles, particles composed of thermally expandable inorganic materials, and particles composed of hydrous porous bodies may also be used. Hereinafter, small-diameter inorganic particles will be referred to as the first inorganic particle 11, and large-diameter inorganic particles as the second inorganic particle 12, and the inorganic particles will be described in more detail.

[0135] (First Inorganic Particle)

[0136] (Oxide particles)

[0137] Oxide particles have a high refractive index, resulting in strong diffuse reflection of light. Therefore, when using oxide particles as inorganic particles, they can suppress radiative heat transfer, especially in high-temperature regions where abnormal heating occurs. Examples of oxide particles include silicon dioxide (SiO2), titanium dioxide (TiO2), and mullite (Al6O3). 13 The oxides used include, but are not limited to, Si2, zirconium oxide (ZrO2), magnesium oxide (MgO), zircon (ZrSiO4), barium titanate (BaTiO3), zinc oxide (ZnO), and aluminum oxide (Al2O3). That is, only one of the aforementioned oxide particles suitable for use as inorganic particles can be used, or two or more oxide particles can be used. In particular, silica 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 blocking radiant heat in high-temperature regions above 500°C. Therefore, silica and titanium dioxide are most preferably used as oxide particles.

[0138] (Average primary particle size of oxide particles: greater than 0.001 μm and less than 50 μm)

[0139] The particle size of oxide particles can sometimes affect the effect of reflecting radiant heat. Therefore, if the average primary particle size is limited to a specified range, higher thermal insulation can be obtained.

[0140] That is, if 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 of heat within the fireproof component 4 can be suppressed, and the thermal insulation performance can be further improved.

[0141] On the other hand, if the average primary particle size of the oxide particles is less than 50 μm, even if they are compressed, the number of contact points between the particles will not increase, making it difficult to form a path for heat conduction. Therefore, it can reduce the impact on insulation performance in the normal temperature range where heat conduction is dominant.

[0142] Furthermore, in this embodiment, the average primary particle size can be calculated by observing the particles under a microscope and comparing them with a standard scale, taking the average of any 10 particles.

[0143] (Nanoparticles)

[0144] In this embodiment, nanoparticles refer to nanoscale particles with an average primary particle size of less than 1 μm that are spherical or nearly spherical. Since nanoparticles have low density, conductive heat transfer is suppressed. If nanoparticles are used as inorganic particles, the voids are further dispersed into smaller particles, thus achieving excellent thermal insulation properties that suppress convective heat transfer. Therefore, when used in batteries within the normal ambient temperature range, nanoparticles are preferred in terms of suppressing heat transfer between adjacent nanoparticles.

[0145] Furthermore, if nanoparticles with a small average primary particle size are used as oxide particles, the increase in heat conduction in the fireproof component 10 can be suppressed even when the fireproof component is compressed due to the expansion accompanying the thermal runaway of the battery cell, resulting in an increase in the internal density of the fireproof component 10. This is believed to be because nanoparticles easily form small gaps between particles due to the repulsive force generated by electrostatics, resulting in a low volume density. Therefore, the particles are filled in a buffering manner.

[0146] Furthermore, in this embodiment, when using nanoparticles as inorganic particles, there are no particular limitations on the material as long as they meet the above definition of nanoparticles. For example, silica nanoparticles are highly insulating materials, and the contact points between the particles are small. Therefore, the heat conducted through silica nanoparticles is less compared to the case where larger silica particles are used. Additionally, the bulk density of silica nanoparticles typically obtained is 0.1 g / cm³. 3Therefore, even when a battery cell arranged adjacent to a fire-resistant component experiences thermal expansion and applies significant compressive stress to the fire-resistant component, the size (area) and number of contact points between the silica nanoparticles in the fire retardant do not increase significantly, thus maintaining thermal insulation. Therefore, silica nanoparticles are preferred as the nanoparticles. Wet silica, dry silica, and aerogels can be used as silica nanoparticles.

[0147] (Average primary particle size of nanoparticles: greater than 1 nm and less than 100 nm)

[0148] If the average primary particle size of the nanoparticles is limited to a specified range, higher thermal insulation performance can be obtained.

[0149] That is, if the average primary particle size of the nanoparticles is set to be greater than 1 nm and less than 100 nm, then, especially in temperature regions below 500 °C, convective and conductive heat transfer within the fireproof component 10 can be suppressed, thereby further improving the thermal insulation performance. In addition, even under compressive stress, the voids remaining between the nanoparticles and the numerous contact points between the particles can suppress conductive heat transfer, maintaining the thermal insulation performance of the fireproof component 10.

[0150] 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.

[0151] (Inorganic hydrate particles)

[0152] When inorganic hydrate particles are heated by a heat source and reach a temperature above the initiation temperature of thermal decomposition, they undergo thermal decomposition, releasing their own water of crystallization and thus lowering the temperature of the heat source and its surroundings, exhibiting what is known as "endothermic effect." Furthermore, after releasing the water of crystallization, they become porous, exhibiting a thermal insulating effect through numerous air pores.

[0153] 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).

[0154] For example, aluminum hydroxide contains approximately 35% water of crystallization. As shown in the following formula, it decomposes thermally to release the water of crystallization, exhibiting an endothermic effect. Furthermore, after releasing the water of crystallization, it becomes alumina (Al2O3), a porous material, and functions as a fire-resistant component.

[0155] 2Al(OH)3→Al2O3+3H2O

[0156] Furthermore, as described later, the fire-resistant member 10 and the elastic member 20 of this embodiment are preferably located between battery cells, but in a battery cell that has experienced thermal runaway, the temperature rises sharply to over 200°C and continues to rise to around 700°C. Therefore, the inorganic particles are also preferably composed of inorganic hydrates with a thermal decomposition start temperature of 200°C or higher.

[0157] Regarding the thermal decomposition start temperatures of the inorganic hydrates listed above, aluminum hydroxide is approximately 200°C, magnesium hydroxide is approximately 330°C, calcium hydroxide is approximately 580°C, zinc hydroxide is approximately 200°C, iron hydroxide is approximately 350°C, manganese hydroxide is approximately 300°C, zirconium hydroxide is approximately 300°C, and gallium hydroxide is approximately 300°C. These temperatures largely overlap with the temperature range of a rapidly rising battery cell that has experienced thermal runaway. They can effectively suppress the temperature rise and are therefore considered preferred inorganic hydrates.

[0158] (Average secondary particle size of inorganic hydrate particles: greater than 0.01 μm and less than 200 μm)

[0159] Furthermore, when inorganic hydrate particles are used as the first inorganic particle 11, if their average particle size is too large, the first inorganic particle 11 (inorganic hydrate) located near the center of the fireproof component 10 will require a certain amount of time to reach its thermal decomposition temperature. Therefore, sometimes the first inorganic particle 11 near the center of the fireproof component 10 cannot be completely thermally decomposed. 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.

[0160] (nitride particles)

[0161] Examples of preferred nitride particles include boron nitride (BN).

[0162] (Carbide particles)

[0163] Examples of preferred carbide particles include boron carbide (B4C).

[0164] (Particles composed of thermally expanding inorganic materials)

[0165] Examples of thermally expandable inorganic materials include vermiculite, bentonite, mica, and perlite.

[0166] (Particles composed of hydrous porous materials)

[0167] Specific examples of hydrous porous materials include zeolite, kaolinite, montmorillonite, acid clay, diatomaceous earth, wet silica, dry silica, aerogel, mica, vermiculite, etc.

[0168] (Inorganic hollow sphere)

[0169] Inorganic particles can also contain inorganic hollow spheres.

[0170] If it contains inorganic hollow spheres, it can suppress convective or conductive heat transfer within the fireproof component 10 in temperature ranges below 500°C, thereby further improving the thermal insulation of the fireproof component 10.

[0171] As an inorganic hollow sphere, at least one of the following can be used: white sand hollow sphere, silica hollow sphere, fly ash hollow sphere, barite hollow sphere, and glass hollow sphere.

[0172] (Inorganic hollow sphere content: less than 60% by mass relative to the total mass of the fireproof component)

[0173] The content of inorganic hollow spheres, relative to the total mass of the fireproof component, is preferably 60% by mass or less.

[0174] (Average particle size of inorganic hollow spheres: greater than 1 μm and less than 100 μm)

[0175] The average particle size of the inorganic hollow spheres is preferably 1 μm or more and 100 μm or less.

[0176] (Second inorganic particle)

[0177] When two types of inorganic particles are present, the second inorganic particle 12 is not particularly limited as long as its material, particle size, etc., are different from those of the first inorganic particle 11. As the second inorganic particle 12, inorganic hollow spheres such as oxide particles, carbide particles, nitride particles, inorganic hydrate particles, silica nanoparticles, metal oxide particles, microporous particles or hollow silica particles, particles made of thermally expandable inorganic materials, and particles made of hydrous porous bodies can be used, as detailed above.

[0178] Furthermore, nanoparticles exhibit extremely low thermal conductivity and maintain excellent thermal insulation even under compressive stress applied to the fire-resistant component. Additionally, metal oxide particles such as titanium dioxide are highly effective at blocking radiant heat. Moreover, when using both large-diameter and small-diameter inorganic particles, the small-diameter particles can penetrate the gaps between the large-diameter particles, resulting in a denser structure and improved heat transfer suppression. Therefore, when using nanoparticles as the first inorganic particle 11, it is preferable that the fire-resistant component 10 contains metal oxide particles with a diameter larger than the first inorganic particle 11 as the second inorganic particle 12.

[0179] Examples of metal oxides include silicon dioxide, titanium dioxide, aluminum oxide, barium titanate, zinc oxide, zircon, and zirconium oxide. Titanium dioxide, in particular, has a higher refractive index compared to other metal oxides, resulting in excellent light diffuse reflection and heat shielding in high-temperature regions above 500°C. Therefore, titanium dioxide is the preferred choice.

[0180] (Average primary particle size of the second inorganic particle)

[0181] When the fireproof component 10 contains second inorganic particles 12 composed of metal oxides, if the average primary particle size of the second inorganic particles 12 is 1 μm or more and 50 μm or less, radiative heat transfer can be effectively suppressed in high-temperature regions above 500°C. The average primary particle size of the second inorganic particles 12 is further preferably 5 μm or more and 30 μm or less, and most preferably 10 μm or less.

[0182] (Content of the first and second inorganic particles)

[0183] When the first inorganic particle 11 is a silica nanoparticle and the second inorganic particle 12 is a metal oxide, if the content of the first inorganic particle 11 is 60% by mass or more and 95% by mass or less relative to the total mass of the first inorganic particle 11 and the second inorganic particle 12, the amount of metal oxide particles required for suppressing radiative heat transfer, as well as the amount of silica nanoparticles required for suppressing and buffering conductive and convective heat transfer, can be optimized.

[0184] The result is that, over a wide temperature range from the normal operating temperature of the battery to temperatures above 500°C, high thermal insulation can be achieved with good balance even when external compressive forces are applied.

[0185] (Inorganic fibers)

[0186] Examples of inorganic fibers include silica fibers, alumina fibers, aluminum silicate fibers, zirconium oxide fibers, carbon fibers, soluble fibers, refractory ceramic fibers, aerogel composites, magnesium silicate fibers, alkaline earth silicate fibers, potassium titanate fibers, potassium titanate whisker fibers and other ceramic fibers, glass fibers, glass wool and other glass fibers, rock wool, basalt fibers, and mineral fibers other than those mentioned above, such as natural mineral fibers like wollastonite.

[0187] These inorganic fibers are preferred in terms of heat resistance, strength, and ease of acquisition. From a processability point of view, silica-alumina fibers, alumina fibers, silica fibers, rock wool, alkaline earth silicate fibers, and glass fibers are particularly preferred.

[0188] There are no particular limitations on the cross-sectional shape of inorganic fibers, including circular cross-sections, flat cross-sections, hollow cross-sections, polygonal cross-sections, and core cross-sections. Among these, fibers with irregular cross-sections such as hollow cross-sections, flat cross-sections, or polygonal cross-sections are preferred because they offer slightly improved thermal insulation.

[0189] Unless the inorganic fibers exhibit the specific properties described later, the preferred lower limit for the average fiber length is 0.1 mm, and more preferably 0.5 mm. Conversely, the preferred upper limit for the average fiber length is 50 mm, and more preferably 10 mm. If the average fiber length is less than 0.1 mm, it is difficult for the inorganic fibers to intertwine, potentially reducing the mechanical strength of the fire-resistant component 10. Conversely, if it exceeds 50 mm, while a reinforcing effect can be achieved, the inorganic fibers cannot be tightly intertwined, or may be rolled up from a single fiber, easily creating continuous gaps, which could lead to a decrease in thermal insulation.

[0190] Unless otherwise specified, 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. If 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 their impact on human health, the average fiber diameter of inorganic fibers is preferably 3 μm or more. On the other hand, if the average fiber diameter of inorganic fibers is greater than 15 μm, the heat transfer of solids using inorganic fibers as a medium increases, which may lead to a decrease in thermal insulation performance. Additionally, it may deteriorate the formability and strength of fire-resistant components.

[0191] Furthermore, inorganic fibers can be used alone or in combination of two or more types. For example... Figure 6As shown, the fire-resistant component 10 preferably has, for example, at least one first inorganic fiber 15 and a second inorganic fiber 16 with different properties selected from average fiber diameter, shape, and glass transition temperature. By containing two inorganic fibers with different properties, the mechanical strength of the fire-resistant component 10 and the retention of inorganic particles can be improved.

[0192] (Two types of inorganic fibers with different average fiber diameters and fiber shapes)

[0193] In the case of containing two types of inorganic fibers, it is preferable that the average fiber diameter of the first inorganic fiber 15 is greater than the average fiber diameter of the second inorganic fiber 16. The first inorganic fiber 15 is linear or needle-like, and the second inorganic fiber 16 is dendritic or crimped. The first inorganic fiber 15 with a larger average fiber diameter (coarser diameter) has the effect of improving the mechanical strength and shape retention of the fireproof component 10. The above-mentioned effect can be obtained by making one of the two inorganic fibers, for example, the diameter of the first inorganic fiber 15, larger than the diameter of the second inorganic fiber 16. External impacts sometimes act on the fireproof component 10; therefore, by containing the first inorganic fiber 15 in the fireproof component 10, the impact resistance is improved. Examples of external impacts include, for example, the compressive force caused by the expansion of the battery unit 110, and the wind pressure caused by the ignition of the battery unit 110.

[0194] Furthermore, to improve the mechanical strength and shape retention of the fireproof component 10, it is particularly preferred that the first inorganic fiber 15 is linear or needle-like. Moreover, linear or needle-like fibers refer to fibers with a crimp of, for example, less than 10%, preferably less than 5%.

[0195] More specifically, in order to improve the mechanical strength and shape retention of the fireproof component 10, the average fiber diameter of the first inorganic fiber 15 is preferably 1 μm or more, and more preferably 3 μm or more. If the first inorganic fiber 15 is too coarse, it may reduce the formability and processability of the fireproof component 10. Therefore, the average fiber diameter of the first inorganic fiber 15 is preferably 20 μm or less, and more preferably 15 μm or less.

[0196] Furthermore, if the first inorganic fiber 15 is too long, its formability and processability may obviously decrease. Therefore, it is preferable to make the fiber length 100 mm or less. Moreover, if the first inorganic fiber 15 is too short, its shape retention and mechanical strength will decrease. Therefore, it is preferable to make the fiber length 0.1 mm or more.

[0197] On the other hand, the second inorganic fiber 16, with its finer average fiber diameter, has the effect of improving the retention of other inorganic fibers, inorganic particles, etc., and improving the flexibility of the fireproof component 10. Therefore, it is preferable that the diameter of the second inorganic fiber 16 is smaller than the diameter of the first inorganic fiber 15.

[0198] More specifically, to improve the retention of other inorganic fibers and particles, the second inorganic fiber 16 is preferably easily deformable and flexible. Therefore, the average fiber diameter of the fine-diameter second inorganic fiber 16 is preferably less than 1 μm, more preferably less than 0.1 μm. However, if the fine-diameter inorganic fiber is too thin, it is prone to breakage, reducing its ability to retain other inorganic fibers and particles. In addition, if it does not retain other inorganic fibers and particles, the proportion of fibers existing in a tangled state in the fireproof member 10 increases, which not only reduces its ability to retain other inorganic fibers and particles but also deteriorates its formability and shape retention. Therefore, the average fiber diameter of the second inorganic fiber 16 is preferably 1 nm or more, more preferably 10 nm or more.

[0199] Furthermore, if the second inorganic fiber 16 is too long, its formability and shape retention will decrease. Therefore, the fiber length of the second inorganic fiber 16 is preferably 0.1 mm or less. Conversely, if the second inorganic fiber 16 is too short, its shape retention and mechanical strength will decrease. Therefore, the fiber length of the second inorganic fiber 16 is preferably 1 μm or more.

[0200] Furthermore, the second inorganic fiber 16 is preferably dendritic or crimped. When the second inorganic fiber 16 is in this shape, it intertwines and interweaves with other inorganic fibers, inorganic particles, etc., within the fire-resistant member 10. Therefore, the retention capacity of other inorganic fibers, inorganic particles, etc., is improved. Additionally, when the fire-resistant member 10 and the elastic member 5 are subjected to compressive force or wind pressure, the interweaving of the first inorganic fiber 15 and the second inorganic fiber 16 suppresses sliding movement of the fire-resistant member 10, thereby particularly increasing its mechanical strength against external compressive force and impact.

[0201] In addition, dendritic refers to a structure that branches in two or three dimensions, such as feather-like, tetrap-like, radial, or three-dimensional network.

[0202] When the second inorganic fiber 16 is dendritic, its average fiber diameter can be obtained by measuring the diameter of the trunk and branches at multiple points using SEM and calculating their average value.

[0203] Furthermore, crimped refers to a structure in which fibers bend in various directions. As one method for quantifying crimped morphology, it is known to calculate the degree of crimp based on electron microscope images, for example, using the following formula.

[0204] crimp (%) = (fiber length - distance between fiber ends) / (fiber length) × 100

[0205] Here, the fiber length and the distance between fiber ends are measured values ​​from electron microscope images. That is, the fiber length and the distance between fiber ends are projected onto a two-dimensional plane, which are shorter than the actual values. According to this formula, the crimp of the second inorganic fiber 16 is preferably 10% or more, more preferably 30% or more. If the crimp is small, it is difficult to form the retention capacity of other inorganic fibers, inorganic particles, etc., and the entanglement (network) between the second inorganic fibers 16 and between the first inorganic fiber 15 and the second inorganic fiber 16.

[0206] In the above embodiments, as a method to improve the mechanical strength, shape retention, and retention of inorganic particles and inorganic fibers of the fire-resistant component 10, a first inorganic fiber 15 and a second inorganic fiber 16 with different average fiber diameters and fiber shapes are used. However, by using the first inorganic fiber 15 and the second inorganic fiber 16 with different glass transition temperatures and average fiber diameters, the mechanical strength, shape retention, and particle retention of the fire-resistant component 10 can also be improved.

[0207] As described above, in this embodiment, in order to improve the mechanical strength, shape retention, and particle retention of the fireproof component 10, it is preferable to use various combinations of inorganic fibers. Hereinafter, [the following will discuss...] Figure 6 The embodiments shown are described using different combinations of the first and second inorganic fibers, but for convenience, in this specification, the following is used: Figure 6 Other embodiments related to inorganic fibers are described.

[0208] (Two inorganic fibers with different glass transition temperatures)

[0209] When the fireproof component 10 contains two kinds of inorganic fibers, the first inorganic fiber 15 is preferably an amorphous fiber, and the second inorganic fiber 16 is at least one kind of fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber 15.

[0210] In addition, by using a first inorganic particle 11 containing at least one of nanoparticles, hollow particles and porous particles in conjunction with the above two types of inorganic fibers, the thermal insulation performance can be further improved.

[0211] The melting point of crystalline inorganic fibers is generally higher than the glass transition temperature of amorphous inorganic fibers. Therefore, when the first inorganic fiber 15 is exposed to high temperatures, its surface softens before that of the second inorganic fiber 16, bonding other inorganic fibers, inorganic particles, etc. Therefore, by including the first inorganic fiber 15 as described above in the fireproof component 10, the mechanical strength of the insulation layer can be improved.

[0212] Specifically, the first inorganic fiber 15 is preferably an inorganic fiber with a melting point of less than 700°C, and many amorphous inorganic fibers can be used. Among them, fibers containing SiO2 are preferred, and glass fibers are more preferred from the perspectives of low price, easy availability, and excellent processability.

[0213] As described above, the second inorganic fiber 16 is a fiber composed of at least one selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber 15. Many crystalline inorganic fibers can be used as the second inorganic fiber 16.

[0214] If the second inorganic fiber 16 is composed of crystalline fibers, or has a higher glass transition temperature than the first inorganic fiber 15, then when exposed to high temperatures, even if the first inorganic fiber 15 softens, the second inorganic fiber 16 will not melt or soften. Therefore, it can maintain its shape and continue to exist between battery cells even in the event of thermal runaway.

[0215] Furthermore, if the second inorganic fiber 16 does not melt or soften, the tiny spaces between the particles, between the particles and the fibers, and between the fibers contained in the fireproof component 10 are maintained, thus achieving an air-based insulation effect and maintaining excellent heat transfer inhibition performance.

[0216] When the second inorganic fiber 16 is crystalline, the second inorganic fiber 16 can be made of ceramic fibers such as silica fiber, alumina fiber, aluminum silicate fiber, zirconium oxide fiber, carbon fiber, soluble fiber, refractory ceramic fiber, aerogel composite material, magnesium silicate fiber, alkaline earth silicate fiber, potassium titanate fiber, glass fiber, glass wool, rock wool, basalt fiber, etc., and other mineral fibers such as wollastonite.

[0217] If the inorganic fiber listed as the second inorganic fiber 16 has a melting point exceeding 1000°C, then even if thermal runaway of the battery cell occurs, the second inorganic fiber 16 will not melt or soften and can maintain its shape, thus it can be used appropriately.

[0218] Furthermore, it is more preferable to use ceramic fibers such as silica fibers, alumina fibers and aluminosilicate fibers, as well as natural mineral fibers, which are listed as the second inorganic fiber 16 above. Among them, it is even more preferable to use fibers with a melting point of more than 1000°C.

[0219] Furthermore, even if the second inorganic fiber 16 is amorphous, it can be used as long as it is a fiber with a glass transition temperature higher than that of the first inorganic fiber 15. For example, a glass fiber with a glass transition temperature higher than that of the first inorganic fiber 15 can also be used as the second inorganic fiber 16.

[0220] Furthermore, as the second inorganic fiber 16, various inorganic fibers, as exemplified, can be used alone, or two or more can be used in combination.

[0221] Furthermore, as described above, the glass transition temperature of the first inorganic fiber 15 is lower than that of the second inorganic fiber 16. When exposed to high temperatures, the first inorganic fiber 15 softens first, thus enabling the bonding of other inorganic fibers, inorganic particles, etc., using the first inorganic fiber 15. However, for example, if the second inorganic fiber 16 is amorphous and its fiber diameter is smaller than that of the first inorganic fiber 15, and if the glass transition temperatures of the first inorganic fiber 15 and the second inorganic fiber 16 are close, the second inorganic fiber 16 may soften first.

[0222] Therefore, when the second inorganic fiber 16 is an amorphous fiber, the glass transition temperature of the second inorganic fiber 16 is preferably 100°C or more higher than the glass transition temperature of the first inorganic fiber 15, and more preferably 300°C or more higher.

[0223] Furthermore, the fiber length of the first inorganic fiber 15 is preferably 100 mm or less, and more preferably 0.1 mm or more. The fiber length of the second inorganic fiber 16 is preferably 0.1 mm or less. These reasons are as described above.

[0224] (Two inorganic fibers with different glass transition temperatures and average fiber diameters)

[0225] When the fireproof component 10 contains two kinds of inorganic fibers, the first inorganic fiber 15 is preferably an amorphous fiber, and the second inorganic fiber 16 is at least one kind of fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber 15. The average fiber diameter of the first inorganic fiber 15 is greater than that of the second inorganic fiber 16.

[0226] As described above, when the fireproof component 10 of this embodiment contains two types of inorganic fibers, it is preferable that the average fiber diameter of the first inorganic fiber 15 is greater than the average fiber diameter of the second inorganic fiber 16.

[0227] Furthermore, the first inorganic fiber 15 with a larger diameter is preferably an amorphous fiber, and the second inorganic fiber 16 with a smaller diameter is a fiber composed of at least one selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber 15. As a result, the first inorganic fiber 15 has a low glass transition temperature and softens earlier, thus hardening into a film as the temperature rises. On the other hand, if the second inorganic fiber 16 with a smaller diameter is a fiber composed of at least one selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber 15, then even if the temperature rises, the second inorganic fiber 16 with a smaller diameter will remain in a fiber shape, thus maintaining the structure of the fireproof component 10 and preventing powder from falling off.

[0228] Furthermore, even in this case, the fiber length of the first inorganic fiber 15 is preferably 100 mm or less, and more preferably 0.1 mm or more. The fiber length of the second inorganic fiber 16 is preferably 0.1 mm or less. These reasons are as described above.

[0229] In addition, the fireproof component 10 may contain different inorganic fibers besides the first inorganic fiber 15 and the second inorganic fiber 16 mentioned above.

[0230] (The respective contents of the first and second inorganic fibers)

[0231] When the fireproof component 10 contains two kinds of inorganic fibers, the content of the first inorganic fiber 15 is preferably 3% or more and 30% or less of the total mass of the fireproof component 10, and the content of the second inorganic fiber 16 is preferably 3% or more and 30% or less of the total mass of the fireproof component 10.

[0232] Furthermore, it is preferable that the content of the first inorganic fiber 15 is 5% by mass or more and 15% by mass or less relative to the total mass of the fireproof component 10, and even more preferably that the content of the second inorganic fiber 16 is 5% by mass or more and 15% by mass or less relative to the total mass of the fireproof component 10. By setting such contents, a good balance is achieved in the shape retention, extrusion resistance, wind pressure resistance based on the first inorganic fiber 15, and the retention capacity of the inorganic particles based on the second inorganic fiber 16.

[0233] (Organic fiber)

[0234] As for organic fiber 18, there are no particular limitations, but synthetic fibers, natural fibers, pulp, etc. can be used. As synthetic fiber, fibers composed of thermosetting resins or thermoplastic resins can be selected, such as synthetic fibers composed of modified polyethylene terephthalate (PET), polyethylene (PE), polypropylene, polyester, nylon, polybutylene terephthalate, polyvinyl alcohol (PVA), polyurethane, ethylene-vinyl alcohol copolymer, polypropylene terephthalate, polyacetal, polytetrafluoroethylene, polyetheretherketone, polyphenylene sulfide, polyamide, polyterephthalamide, etc.

[0235] The following provides a more detailed description of the types and structures of synthetic fibers that can be used in this embodiment.

[0236] Vinylon: A fiber composed of long-chain synthetic polymers containing more than 65% vinyl alcohol units by mass.

[0237] Polyvinyl alcohol (vinyl alcohol): A fiber composed of long-chain synthetic polymers of polyvinyl alcohol with varying degrees of acetalization.

[0238] Polyvinyl chloride (chlorofiber): A fiber composed of long-chain synthetic polymers with vinyl chloride units as the main component.

[0239] Polyvinylidene chloride (chlorofiber): A fiber composed of long-chain synthetic polymers with vinylidene chloride units (-CH2-CCl2-) as the main component.

[0240] Acrylonitrile fiber: A fiber composed of long-chain synthetic polymers containing repeating units of acrylonitrile groups at a mass ratio of more than 85%.

[0241] Polyacrylonitrile fiber (modacrylic): A fiber composed of long-chain synthetic polymers containing repeating units of acrylonitrile groups at a mass ratio of more than 35% and less than 85%.

[0242] Nylon (polyamide): A fiber composed of long-chain synthetic polymers in which more than 85% of the repeating amide bonds are bonded to aliphatic or cyclic aliphatic units.

[0243] Aromatic polyamide fiber: A fiber composed of a long-chain synthetic polymer in which the mass ratio of amide or imide bonds directly bonded to two benzene rings is more than 85%, and in the case of imide bonds, their number does not exceed the number of amide bonds.

[0244] Polyester fiber: A fiber composed of long-chain synthetic polymers containing ester units of terephthalic acid and diol in a mass ratio of more than 85%.

[0245] Polyethylene terephthalate (PET): A fiber composed of long-chain synthetic polymers containing ester units of terephthalic acid and ethylene glycol in a mass ratio of more than 85%.

[0246] Poly(propylene terephthalate) (PTT): A fiber composed of long-chain synthetic polymers containing ester units of terephthalic acid and 1,3-propanediol in a mass ratio of more than 85%.

[0247] Polybutylene terephthalate (PBT): A fiber composed of long-chain synthetic polymers containing ester units of terephthalic acid and 1,4-butanediol in a mass ratio of more than 85%.

[0248] Polyethylene (PE): A fiber composed of long-chain synthetic polymers, which are composed of unsubstituent saturated aliphatic hydrocarbons.

[0249] Polypropylene (PP) is a fiber composed of a long-chain synthetic polymer consisting of saturated aliphatic hydrocarbons with methyl side chains in one carbon atom for every two molecules. It is stereoregular and has no substituents.

[0250] Polyurethane (elastane): A fiber composed of a long-chain synthetic polymer containing more than 85% polyurethane segments by mass, which, when stretched to three times its length without tension, immediately returns to its original length when the tension is removed.

[0251] Polylactic acid (PLA): A fiber composed of long-chain synthetic polymers containing more than 50% lactate units by mass.

[0252] The preferred ranges for the average fiber length and average fiber diameter of organic fiber 18 are the same as those for inorganic fiber.

[0253] (Other materials)

[0254] In addition to the first inorganic particles 11 and the second inorganic particles 12, the first inorganic fiber 15 and the second inorganic fiber 16, and the organic fiber 18 described above, the fireproof component 10 that can be used in this embodiment may also contain components required for molding the fireproof component, such as binders and colorants. The other components will also be described in detail below.

[0255] (Combined materials)

[0256] Even if the fireproof component 10 of this embodiment does not contain a binder material 19 such as an adhesive, it can be formed by sintering or the like. In particular, when the fireproof component 10 contains silica nanoparticles, it is preferable to add the binder material 19 in an appropriate amount in order to maintain the shape of the fireproof component 10.

[0257] In this embodiment, the binding material 19 can be any material used to connect and fix the inorganic particles, and its form is not limited. It can be an adhesive with bonding properties, fibers that physically entangle the particles, heat-resistant resin that is attached by adhesive force, etc. The first inorganic fiber 15 and the second inorganic fiber 16 mentioned above also function as the binding material 19.

[0258] Furthermore, organic adhesives, inorganic adhesives, etc., can be used as the binder material 19. In this embodiment, there are no particular limitations on the types of binders, but as organic adhesives, polymeric materials and acrylic emulsions can be used, and as inorganic adhesives, silica sol, alumina sol, aluminum sulfate, etc., can be used. They function as the binder material 19 when solvents such as water are removed.

[0259] In the fireproof component 10 used in this embodiment, the content of the bonding material 19 relative to the total mass of the fireproof component 10 is preferably 60% by mass or less, more preferably 50% by mass or less. In the fireproof component 10 used in this embodiment, the content of the bonding material 19 relative to the total mass of the fireproof component 10 is preferably 10% by mass or more, more preferably 20% by mass or more.

[0260] (Thickness of fire-resistant components)

[0261] The thickness of the fireproof component 10 used in this embodiment is not particularly limited, but it is preferably in the range of 0.1 mm or more and 30 mm or less. If the thickness of the fireproof component 10 is within the above range, sufficient heat insulation and mechanical strength can be obtained, and it can be easily molded.

[0262] [Elastic Components]

[0263] As the elastic component 20 in this embodiment, rubber or an elastomer can be used, for example.

[0264] Next, the battery pack according to an embodiment of the present invention will be described.

[0265] [Battery Pack]

[0266] Figure 7 This is a schematic cross-sectional view of a battery pack 100 according to an embodiment of the present invention.

[0267] The battery pack 100 is formed by housing multiple battery cells 110 in a battery housing 120. The fireproof sheet 1 can be arranged between adjacent battery cells 110, and thus arranged in the space between the battery cells 110 and the battery housing 120, just like the top cover, side wall and bottom wall of the battery housing 120.

[0268] Furthermore, the fireproof sheet 1 can be in contact with the battery cell 110 or there can be a gap between them. Even when there is no gap between the fireproof sheet 1 and the battery cell 110, the fireproof sheet 1 has an elastic member 20, so that the deformation of the battery cell 110 can be allowed when the temperature of either battery cell 110 rises and its volume expands.

[0269] In addition, the battery casing 120 can be made of polycarbonate, PP, PET, polyamide (PA), aluminum, stainless steel (SUS), etc. Furthermore, the shape of the battery casing 120 can be freely selected according to the application location.

[0270] The various embodiments have been described above, but the present invention is not limited to these examples. Those skilled in the art will obviously be able to conceive of various modifications or alterations within the scope described in the application documents, and it should be understood that these 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.

[0271] Furthermore, this application is based on Japanese Patent Application No. 2022-053783, filed on March 29, 2022, and the contents of the aforementioned Japanese Patent Application are referenced and incorporated herein by reference.

Claims

1. A fireproof sheet, The fireproof sheet is composed of layers of fireproof components and elastic parts, and, The mating surfaces of the fireproof component and the elastic member are engaged in a manner that allows them to slide along the surfaces where the mating surfaces are located. The fireproof component and the elastic component are joined by at least one of the following joining components: resin clips and resin needles.

2. The fireproof sheet according to claim 1, characterized in that, The joining components are arranged such that the distribution density on the outer periphery of the surface of the fireproof sheet is higher than the distribution density on the central portion of the surface of the fireproof sheet.

3. The fireproof sheet according to claim 1 or 2, characterized in that, The elastic component is formed of an elastomer.

4. The fireproof sheet according to claim 1 or 2, characterized in that, The fireproof component contains at least one of inorganic particles, organic fibers, and inorganic fibers.

5. The fireproof sheet according to claim 4, characterized in that, The inorganic particles are particles composed of at least one type of inorganic material selected from oxide particles, carbide particles, nitride particles and inorganic hydrate particles.

6. The fireproof sheet according to claim 1 or 2, characterized in that, The fireproof component has at least one first inorganic fiber and a second inorganic fiber with different properties selected from average fiber diameter, shape and glass transition temperature.

7. The fireproof sheet according to claim 6, characterized in that, The average fiber diameter of the first inorganic fiber is greater than the average fiber diameter of the second inorganic fiber. The first inorganic fiber is linear or needle-like, and the second inorganic fiber is dendritic or crimped.

8. The fireproof sheet according to claim 6, characterized in that, The first inorganic fiber is an amorphous fiber. The second inorganic fiber is at least one type of fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber. The average fiber diameter of the first inorganic fiber is greater than the average fiber diameter of the second inorganic fiber.

9. The fireproof sheet according to claim 6, characterized in that, The fireproof component contains inorganic particles, which include at least one type selected from nanoparticles, hollow particles, and porous particles. The first inorganic fiber is an amorphous fiber. The second inorganic fiber is at least one inorganic fiber selected from crystalline fibers and amorphous fibers with a glass transition temperature higher than that of the first inorganic fiber.

10. The fireproof sheet according to claim 3, characterized in that, The elastic component is made of rubber.

11. A method for manufacturing a fireproof sheet, wherein the fireproof sheet is the fireproof sheet according to any one of claims 1 to 10, and in the manufacturing method, The fireproof component and the elastic component are joined in such a manner that the joint surface of the fireproof component engaging with the elastic component and the joint surface of the elastic component engaging with the fireproof component can slide along the surface where the joint surface is located. The fireproof component is joined to the elastic member using at least one of resin-made rivets and resin-made needles.

12. A battery pack having: A plurality of battery cells; a battery housing that houses the battery cells; and a fireproof sheet according to any one of claims 1 to 10.

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