SILICON OXIDE AEROGEL POWDER USED IN A THERMAL INSULATOR FOR A BATTERY PACK, AND THERMAL INSULATOR FOR A BATTERY PACK

Abstract

When a silicon oxide aerogel powder used in a thermal insulator for a battery pack is measured using a nitrogen adsorption quantity measurement method, the specific surface area and pore volume at a relative pressure of 0.99, measured on the basis of an obtained adsorption isotherm, are 550 m². 2 / g or more or 3.5 mL / g or more and 5.0 mL / g or less, and if a [mL / g] is a pore volume at a relative pressure of 0.93, b [mL / g] is a pore volume at a relative pressure of 0.965 and c [mL / g] is a pore volume at a relative pressure of 0.99, then the following conditions (i) and (ii) are satisfied: 0 ≤ ( a / c × 100 ) ≤ 50 50 ≤ ( b / c × 100 ) < 100

Description

TECHNICAL AREA

[0001] The present disclosure relates to a thermal insulator arranged between adjacent battery cells in a battery pack containing a plurality of battery cells, and in particular to a thermal insulator in which a silicon oxide aerogel powder or a silicon oxide aerogel is used. STATE OF THE ART

[0002] A battery pack containing multiple battery cells is installed in electric hybrid vehicles and battery electric vehicles. Within the battery pack, a battery module, formed by laminating multiple battery cells, is housed in a casing in a state where the battery module is secured by fasteners on both sides in a lamination direction. A thermal insulator is positioned between adjacent battery cells to prevent heat transfer and thermal runaway in the event of abnormal overheating. Battery cells expand and contract as a result of charging and discharging. Therefore, it is preferred that the thermal insulator positioned between the battery cells be able to deform in response to this expansion and contraction while maintaining thermal insulation.In particular, when the battery cell is charged and expands, the thickness of the thermal insulator is reduced due to the compressive force. Simultaneously, a reaction force of a certain value or higher is required to energize the battery cell and prevent it from shifting. Furthermore, when the battery cell discharges and contracts (returning to its original thickness), the thickness of the thermal insulator must also be restored.

[0003] Silicon oxide aerogels with low thermal conductivity are known as thermal insulating materials. For example, patent document 1 describes an aerogel powder with excellent flexibility and resistance to fracture under compressive force, wherein the aerogel powder is made from an aerogel that is a hydrolysis condensation product of a silane compound. The silane compound as the starting material satisfies 0 ≤ Qx ≤ 70, 30 ≤ Tx ≤ 100, 0 ≤ Dx < 30 (where Qx + Tx + Dx = 100), where Qx, Tx, and Dx are mass percentages of a tetrafunctional silane compound, a trifunctional silane compound, and a bifunctional silane compound, respectively. Patent document 2 describes a silicon oxide aerogel as an example of an aerogel used in an aerogel composite.Paragraphs

[0023] and

[0025] of patent document 2 describe the physical and structural properties of the aerogel as (a) an average pore diameter of 2 nm to 100 nm, (b) a porosity of 80 % or more, (c) a surface area of ​​20 m. 2 / g or more, (d) a pore volume of 2.0 mL / g or more and the like, which are determined by a nitrogen porosity measurement test. State-of-the-art documents, patent documents Patent document 1: Japanese unexamined patent application with publication number 2021-165387 (JP 2021-165387 A) Patent document 2: Japanese unexamined patent application with publication number 2023-27128 (JP 2023-27128 A) SUMMARY OF THE INVENTION Problem to be solved by the invention

[0004] Patent document 1 describes the use of a predetermined silane compound as a starting material to improve the flexibility and fracture resistance (a property that fractures are difficult to achieve) of the aerogel powder under compressive force. However, patent document 1 does not describe how a silicon oxide aerogel is endowed with compression recovery, i.e., the ability to deform under load and return to its original state after the load is removed. Furthermore, patent document 1 describes how, when pores are approximated as tubes and the inner diameter of the tube is approximated as a circle, the pore size of the aerogel is in the range of 5 nm or more and 100 nm or less. Additionally, patent document 1 describes how the inner diameter of the tube is identical to the mean free path of the element molecules that make up air at atmospheric pressure.Patent document 1, however, simply describes the size of the pore section (the pores) of the aerogel, but does not provide any technical concept that focuses on and defines the pore structure in such a way as to achieve desired properties. Similarly, patent document 2 describes the surface area and pore volume values ​​as the general structure of the aerogel, and there is no investigation of the pore structure.

[0005] The present disclosure was made in light of the foregoing circumstances and provides a silicon oxide aerogel powder exhibiting excellent thermal insulation and compression recovery, which is used in a thermal insulator for a battery pack, and a thermal insulator for a battery pack in which this is used. The present disclosure also provides a thermal insulator for a battery pack in which a silicon oxide aerogel with excellent thermal insulation and compression recovery is used. Means to solve the problem

[0006] (1) To solve the above problem, a silicon oxide aerogel powder of the present disclosure is a silicon oxide aerogel powder used in a thermal insulator for a battery pack and is characterized in that, when the silicon oxide aerogel powder is measured by a nitrogen adsorption quantity measurement method, a specific surface area and a pore volume at a relative pressure of 0.99, measured on the basis of an adsorption isotherm obtained, are 550 m² 2 / g or more or 3.5 mL / g or more and 5.0 mL / g or less, and if a [mL / g] is a pore volume at a relative pressure of 0.93, b [mL / g] is a pore volume at a relative pressure of 0.965, and c [mL / g] is a pore volume at a relative pressure of 0.99, the following conditions (i) and (ii) are met: 0≤(a / c×100)≤50 50≤(b / c×100)<100.

[0007] In the present disclosure, the pore structure of the silicon oxide aerogel powder is defined such that the desired thermal insulation and compression recovery are achieved. First, the specific surface area is set to 550 m². 2By increasing the pressure (in grams or more) the proportion of micropores (so-called micropores) with a pore diameter (pore size) of approximately several nanometers is reduced. This increases the relative proportion of pores with a pore diameter of approximately 30 to 68 nm, where the pores are effective for improving thermal insulation. Secondly, by adjusting the pore volume at a relative pressure of 0.99 to 3.5 mL / g or more and 5.0 mL / g or less, the proportion of pores with a desired pore diameter is increased. In the nitrogen adsorption quantity measurement method, assuming the pore shape is cylindrical, the measured "pore volume at a relative pressure of 0.99" can be considered the volume of pores with a pore diameter up to approximately 100 nm.If many large pores with a pore diameter greater than 100 nm are present, thermal insulation is reduced, the matrix tends to collapse during compression, and consequently, the desired resilience is not achieved. Therefore, in the silicon oxide aerogel powder of the present disclosure, by concentrating on the pore volume at a relative pressure of 0.99 and adjusting the pore volume to a value within a predetermined range, particles containing a large number of pores with a pore diameter greater than 100 nm are excluded, so that the silicon oxide aerogel powder contains pores with a pore diameter that contributes to thermal insulation and compression resilience.

[0008] The nitrogen adsorption quantity measurement method assumes that the pore volume, which includes pores with a pore diameter greater than 100 nm, cannot be measured in a range where the relative pressure is 0.99 or less. However, in the present disclosure, since the desired pores are those that contribute to the thermal insulation and compression recovery of the silicon oxide aerogel powder, the foregoing conditions (i) and (ii) are adjusted under the assumption that the “pore volume at a relative pressure of 0.99” is close to the “total pore volume”.In the nitrogen adsorption quantity measurement method, if the pore shape is assumed to be cylindrical, the "pore volume at a relative pressure of 0.93" can be considered the volume of pores with a pore diameter up to about 30 nm, and the "pore volume at a relative pressure of 0.965" can be considered the volume of pores with a pore diameter up to about 68 nm.

[0009] According to condition (i), if the fraction of the pore volume (a) at a relative pressure of 0.93 is 50% or less, the number of pores with a diameter up to approximately 30 nm decreases, and the number of pores with a relatively large diameter increases, which is advantageous for improving compression resilience. According to condition (ii), if the fraction of the pore volume (b) at a relative pressure of 0.965 is 50% or more, the number of pores with a diameter equal to or smaller than the mean free path (68 nm) of air increases. In pores with a diameter equal to or smaller than the mean free path of air, thermal conductivity is minimized. Therefore, an increase in the number of such pores is advantageous for improving thermal insulation.As a result, the silicon oxide aerogel powder of the present disclosure, in which the specific surface area and the pore volume are within specified ranges at a relative pressure of 0.99 and conditions (i) and (ii) are met, exhibits very good thermal insulation and excellent compression recovery.

[0010] (2) A first thermal insulator for a battery pack according to the present disclosure comprises the silicon oxide aerogel powder according to the preceding structure (1). According to the thermal insulator for a battery pack according to the present disclosure, the thermal insulator deforms in response to the expansion and contraction of the battery cells, and consequently, positional displacement can be prevented and very good thermal insulation can be maintained. Furthermore, since the expansion and contraction of the battery cells are maintained in a suitable manner, this can contribute to extending the service life of the battery cells.

[0011] (3) In the structure according to (2), the thermal insulator for a battery pack of the present disclosure can comprise a molded component of a composition containing the silicon oxide aerogel powder. In the molded component, the silicon oxide aerogel particles are in contact with each other at points, lines, or surfaces, and the extent of deformation in the thickness direction increases because the particles move in an offset manner when compressed from the outside.

[0012] (4) In the assembly according to (2) or (3), the thermal insulator for a battery pack of the present disclosure may further comprise at least one selected from infrared shielding particles, inorganic fibers and dispersants. In the assembly according to (3), a composition comprising a silicon oxide aerogel powder and at least one selected from infrared shielding particles, inorganic fibers and dispersants may be produced, and a molded component may be produced.

[0013] The thermal insulator, which utilizes silicon dioxide aerogel powder, primarily prevents conduction and convection—three forms of heat transfer (conduction, convection, and radiation)—and consequently achieves a very good thermal insulation effect. Radiation is a phenomenon in which heat is transferred by electromagnetic waves, and the higher the temperature, the greater the amount of emitted radiant energy. Therefore, in a high-temperature atmosphere, radiation becomes the main factor in heat transfer. Infrared shielding particles absorb heat from a heat source, re-emit the absorbed heat from the surface on the side facing the heat source, and thus block radiant heat from the heat source.Therefore, when infrared shielding particles, which prevent heat transfer due to radiation, are used in combination, heat transfer due to radiation can be prevented in addition to conduction and convection, and very good thermal insulation can be achieved not only at room temperature but also at high temperatures of 500 °C or higher. Furthermore, the mechanical strength of the thermal insulator can be improved by adding inorganic fibers, and the risk of silicon dioxide aerogel particles detaching can be prevented. Silicon dioxide aerogel powder does not mix easily with water and does not disperse readily. Therefore, the dispersibility of the silicon dioxide aerogel powder can be improved by adding an amphiphilic dispersant when water is used in the thermal insulator manufacturing process.Furthermore, the addition of a dispersing agent can improve the molding properties of the silicon oxide aerogel powder.

[0014] (5) In the structure according to any of (2) to (4), the silicon oxide aerogel powder can have an average particle size of 30 µm or more and 150 µm or less. This structure is preferred with regard to improving thermal insulation, maintaining strength, and preventing a situation in which the silicon oxide aerogel particles fall off.

[0015] (6) In the construction according to one of (2) to (5), the thermal insulator for a battery pack of the present disclosure can be used in a vehicle. According to this construction, even if oscillation or vibration and the like occur during the movement or driving of the vehicle, displacement of the battery cells can be prevented and very good thermal insulation can be maintained.

[0016] (7) A second thermal insulator for a battery pack according to the present disclosure is a thermal insulator for a battery pack, wherein the thermal insulator comprises a silicon oxide aerogel and is characterized in that, when the silicon oxide aerogel powder is measured by a nitrogen adsorption quantity measurement method, a specific surface area and a pore volume at a relative pressure of 0.99, measured on the basis of an adsorption isotherm obtained, are 550 m² 2 / g or more or 3.5 mL / g or more and 5.0 mL / g or less, and if a [mL / g] is a pore volume at a relative pressure of 0.93, b [mL / g] is a pore volume at a relative pressure of 0.965, and c [mL / g] is a pore volume at a relative pressure of 0.99, the following conditions (i) and (ii) are met: 0≤(a / c×100)≤50 50≤(b / c×100)<100.

[0017] The silicon oxide aerogel, which forms the second thermal insulator for a battery pack of the present disclosure, has a specific surface area and pore volume at a relative pressure of 0.99 within specified ranges and fulfills conditions (i) and (ii) according to the silicon oxide aerogel powder described in (1). Therefore, the silicon oxide aerogel in this configuration exhibits very good thermal insulation and excellent compression recovery. Consequently, according to the second thermal insulator for battery packs of the present disclosure, the thermal insulator deforms in response to the expansion and contraction of the battery cells, and thus positional displacement can be prevented and very good thermal insulation maintained.Furthermore, by maintaining the expansion and contraction of the battery cells in a suitable manner, this can contribute to extending the lifespan of the battery cells.

[0018] (8) In the setup according to (7), the thermal insulator for a battery pack of the present disclosure can further comprise at least one selected from infrared shielding particles and dispersants. As described in (4), when infrared shielding particles are used in combination, heat transfer due to radiation can be prevented in addition to conduction and convection, and very good thermal insulation can be achieved not only at room temperature but also at a high temperature of 500 °C or higher. Furthermore, the silicon oxide aerogel does not simply mix with water and is not simply dispersed. Therefore, if an amphiphilic dispersant is added, the dispersibility of the silicon oxide aerogel can be improved when water is used in the process for producing the thermal insulator.

[0019] (9) In the configuration according to (7) or (8), the thermal insulator for a battery pack of the present disclosure can be used in a vehicle. According to this configuration, even if oscillation or vibration occurs while the vehicle is moving or driving, displacement of the battery cells can be prevented and very good thermal insulation can be maintained.

[0020] (10) In the structure according to one of (7) to (9), the thermal insulator for a battery pack of the present disclosure may further comprise a fiber material. According to this structure, the mechanical strength of the thermal insulator may be improved. Effects of the invention

[0021] Since the silicon oxide aerogel powder and the silicon oxide aerogel of the present disclosure have a special pore structure with a large proportion of pores that contribute to thermal insulation and compression recovery, they exhibit very good thermal insulation and excellent compression recovery. The thermal insulator for a battery pack of the present disclosure, which utilizes the silicon oxide aerogel powder or the silicon oxide aerogel of the present disclosure, can deform in response to a deformation of a counter element and exhibits a very good thermal insulation effect. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. Figure 1 is a graph showing adsorption isotherms of silicon oxide aerogel powders of examples and comparison examples. [ Fig. 2A] Fig.Figure 2A is a schematic view showing the construction of an upper element and a lower element that form a compression device. [ Fig. 2B] Fig. Figure 2B is a schematic view showing a state of the device at maximum compression. [ Fig. 2C] Fig. 2C is a schematic view showing the state of the device after unloading. [ Fig. 3] Fig. Figure 3 is a graph showing a relationship between compressibility and pressure stress in a tenth compression-release cycle. MODES FOR EXECUTING THE INVENTION

[0022] The silicon oxide aerogel powder and the thermal insulator for a battery pack of the present disclosure are described in detail below. The silicon oxide aerogel powder and the thermal insulator for a battery pack of the present disclosure are not limited to the following forms and can be implemented in various forms, which can be modified and improved by a person skilled in the art without departing from the essence and scope of the present disclosure. <siliziumoxidaerogel-pulver>

[0023] Silicon oxide aerogel particles have a backbone formed by the bonding of a plurality of primary particles, and pores are formed between the backbones. It is preferred that the diameter of the primary particles forming the backbone is approximately 2 to 5 nm. The specific surface area and pore volume of the silicon oxide aerogel powder of the present disclosure are measured based on the adsorption isotherm obtained by a nitrogen adsorption quantity measurement method. The nitrogen adsorption quantity measurement method is a technique for measuring a phenomenon in which nitrogen gas molecules are physically adsorbed onto the surface of a solid (silicon oxide aerogel) due to an intermolecular force at a low temperature (liquid nitrogen temperature).The adsorption isotherm is a curve obtained by measuring the amount of adsorption while the pressure of nitrogen gas is increased, and plotting the relative pressure of nitrogen gas on the horizontal axis and the amount of adsorption of nitrogen gas on the vertical axis, as shown in the figure below. Fig. Figure 1 shows the relative pressure on the horizontal axis. This is the ratio (P / P0) of the adsorption equilibrium pressure (P) of the nitrogen gas to the saturation vapor pressure (P0).

[0024] The specific surface area and pore volume values ​​in this description are obtained by measuring the nitrogen gas adsorption quantity using an Autosorb iQ high-vacuum physisorption / chemisorption analyzer (available from Anton Paar). The specific surface area is calculated using a BET multi-point method based on the nitrogen gas adsorption quantity within a relative pressure range of 0.1 to 0.3. The pore volumes at relative pressures of 0.99, 0.965, and 0.93 are calculated using a BJH method based on the respective nitrogen gas adsorption quantities. [Specific surface]

[0025] The specific surface area of ​​the silicon oxide aerogel powder of the present disclosure is 550 m². 2 / g or more. This is because when the specific surface area is less than 550 m² 2 / g, the proportion of micropores with a pore diameter of approximately several nanometers increases, and the proportion of pores with a pore diameter of approximately 30 to 68 nm, where the pores are effective in improving thermal insulation, decreases. [Pore volume at a relative pressure of 0.99]

[0026] The pore volume at a relative pressure of 0.99 of the silicon oxide aerogel powder of the present disclosure, where the pore volume is measured by the nitrogen adsorption quantity method, is 3.5 mL / g or more and 5.0 mL / g or less. Since this condition excludes particles containing a large number of pores with a pore diameter greater than 100 nm, a silicon oxide aerogel powder containing a large number of pores with a pore diameter that contributes to thermal insulation and compression recovery can be realized. [Conditions (i) and (ii)]

[0027] If the pore volume at a relative pressure of 0.93 a [mL / g] is, the pore volume at a relative pressure of 0.965 b [mL / g] is, and the pore volume at a relative pressure of 0.99 c [mL / g] is, as measured by the nitrogen adsorption quantity measurement method, then the silicon oxide aerogel powder of the present disclosure satisfies the following conditions (i) and (ii). 0≤(a / c×100)≤50 50≤(b / c×100)<100

[0028] Condition (i) is a condition that primarily concerns compression recovery and specifies that there are no or only a small number of pores with a pore diameter of up to approximately 30 nm. Condition (ii) is a condition that primarily concerns thermal insulation and specifies that there are many pores with a pore diameter of up to approximately 68 nm. <Verfahren zur Herstellung des Siliziumoxidaerogel-Pulvers>

[0029] The silicon oxide aerogel powder of this disclosure can be produced by a sol-gel reaction of a silane compound. For the sake of simplifying the design of the backbone and pore structure of the silicon oxide aerogel in a desired state, two or more types of compounds with varying numbers of siloxane bonds can be used as the silane compound. In this description, the term "siloxane bond" in the silane compound refers to a bond (Si-O bond) between a silicon atom (Si) and an oxygen atom (O). Here, "number of siloxane bonds" refers to the number of oxygen atoms bonded to a single silicon atom, and the silane compounds are classified into four types, with the number of siloxane bonds ranging from 1 to 4.Silane compounds can include compounds with different numbers of siloxane bonds or can include a plurality of types of compounds with the same number of siloxane bonds.

[0030] To increase the degree of elastic deformation of the silicon dioxide aerogel powder, the silane compound is preferably present in the form of a tetrafunctional silane compound and a trifunctional silane compound. In this form, the content of the trifunctional silane compound is preferably 65 wt% or more, based on 100 wt% of the total silane content. More preferably, the content is 70 wt% or more, and even more preferably, 80 wt% or more. Increasing the content of the trifunctional silane compound reduces the proportion of -O-Si-O bonds in the resulting silicon dioxide aerogel powder. Furthermore, the proportion of pores with a relatively large pore diameter increases. This can further enhance the degree of elastic deformation of the silicon dioxide aerogel powder.On the other hand, with a view to increasing the proportion of pores with a relatively small pore diameter, wherein the pores are effective for improving thermal insulation, the content of the tetrafunctional silane compound is preferably 5 wt% or more and more preferably 10 wt% or more based on 100 wt% of the total content of the silane compounds.

[0031] The structure of the silane compound used in the production of silicon oxide aerogel powder can be achieved by a dipolar decoupling (DD) process using a solid-state 29 Si-NMR analysis. That is, in the solid-state 29 The Si-NMR spectrum of the silicon oxide aerogel powder corresponds to the abundance fractions of the Q unit, the T unit, the D unit and the M unit (the Q unit in which one silicon atom is bonded to four oxygen atoms, the T unit in which one silicon atom is bonded to three oxygen atoms, the D unit in which one silicon atom is bonded to two oxygen atoms, and the M unit in which one silicon atom is bonded to one oxygen atom), which are calculated from the signal area, and the contents of the tetrafunctional silane compound, the trifunctional silane compound, the bifunctional silane compound and the monofunctional silane compound contained in the silane compound-containing solution.

[0032] Examples of tetrafunctional silane compounds include tetraalkoxysilane and tetraacetoxysilane. The alkoxy group of tetraalkoxysilane preferably has 1 to 9 carbon atoms. Examples include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetraisopropoxysilane. Examples of trifunctional silane compounds include trialkoxysilane and triacetoxysilane. The alkoxy group of trialkoxysilane preferably has 1 to 9 carbon atoms. Examples include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, pentyltriethoxysilane, hexyltriethoxysilane, and octyltriethoxysilane. Examples of bifunctional silane compounds include dialkoxysilane and diacetoxysilane. The alkoxy group of the dialkoxysilane preferably has 1 to 9 carbon atoms.Examples include dimethyldimethoxysilane, diethyldimethoxysilane, and diisobutyldimethoxysilane. Examples of monofunctional silane compounds include methoxytrimethylsilane, isopropoxytrimethylsilane, ethoxytrimethylsilane, tert-butoxytrimethylsilane, ethoxytriethylsilane, methoxydimethyl(phenyl)silane, trimethyl(vinyloxy)silane, and isopropenyloxytrimethylsilane.

[0033] The process for producing a silicon oxide aerogel powder via the sol-gel reaction comprises a sol formation step, a gelation step, and a drying step. To obtain a desired pore structure, the conditions, such as the agents used, the temperature, and the time in each step, can be adjusted appropriately. First, in the sol formation step, a sol is formed by adding a predetermined silane compound to an aqueous solution containing an acid catalyst and hydrolyzing the silane compound. An organic solvent, a surfactant, a water-soluble oligomer with both polar and nonpolar side chains, and the like can be added to the aqueous solution. An alcohol-based solvent is preferred as the organic solvent, considering its compatibility after the hydrolysis of the silane compound with an acid catalyst.Examples include methanol, ethanol, and isopropyl alcohol. Next, in the gelation step, a basic catalyst is added to the formed sol, causing polycondensation of the sol to form a gel. A quaternary ammonium salt is preferred as the basic catalyst; for example, tetramethylammonium hydroxide can be used. After adding the basic catalyst, the mixture can be left to stand and harden for 6 to 12 hours at 90 to 120 °C to promote the polycondensation reaction and form a desired pore structure. The resulting gel is then dried in the drying step. The drying process can be either supercritical or non-supercritical (normal pressure drying, freeze-drying).For example, if drying is carried out at atmospheric pressure, it can be performed by heating to 80 to 100 °C for 2 to 3 hours. Aerogels, such as silicon dioxide aerogels, are sometimes distinguished based on the difference in drying methods used during production: "xerogel" when dried at atmospheric pressure, "aerogel" when dried under supercritical conditions, and "cryogel" when freeze-dried; however, in this description, they are all referred to collectively as "aerogel".

[0034] If drying is carried out at atmospheric pressure, a solvent replacement step can be performed prior to the drying step, in which water adhering to the gel is replaced by an organic solvent that can be removed at atmospheric pressure. Furthermore, since drying at atmospheric pressure is slower compared to supercritical drying, there is a risk that pores may shrink due to the action of the basic catalyst remaining in the gel, and a desired pore structure may not be obtained. To prevent pore contraction during drying, it is preferable to perform a washing step in which the basic catalyst is removed from the gel prior to the drying step.The gel can be washed by heating it, for example, to 40 to 50 °C, adding the organic solvent used in the sol formation step, and releasing the basic catalyst due to the concentration difference between the interior and exterior of the gel. On the other hand, if supercritical drying is performed, the rapid drying process makes pore contraction less likely, even if the basic catalyst remains in the gel. However, if the basic catalyst remains in the silicon dioxide aerogel, there is a risk of thermal decomposition. Therefore, even when supercritical drying is used, it is preferable to perform a washing step in which the basic catalyst is removed from the gel before the drying step.A silicon oxide aerogel powder can be produced by comminuting the obtained silicon oxide aerogel using a medialess comminution and a mixing device, such as a jet mill, a stirrer and the like. <Thermischer Isolator für ein Batteriepack>

[0035] A first thermal insulator for a battery pack according to the present disclosure is formed using the silicon oxide aerogel powder of the present disclosure. A first embodiment of the first thermal insulator for a battery pack according to the present disclosure comprises a form in which a molded component of a composition containing a silicon oxide aerogel powder is included. A second embodiment comprises a form in which a thermal insulating layer is included, wherein the thermal insulating layer is produced by applying a liquid (including a slurry) composition, obtained by adding a solvent, such as water, to a silicon oxide aerogel powder, to a substrate and drying the substrate.These two forms of composition can consist solely of a silicon oxide aerogel powder or can be formed by adding further components to a silicon oxide aerogel powder. Furthermore, a second thermal insulator for a battery pack according to the present disclosure can be produced from a silicon oxide aerogel generated by the sol-gel reaction of the silane compound without forming it as a powder.

[0036] When silicon oxide aerogel powder is used, the average particle size can be 10 µm or more to improve thermal insulation. In the form of the molded component, the average particle size is preferably 30 µm or more, and more preferably 50 µm or more, to reduce fine voids between particles and increase strength. On the other hand, to achieve easy molding into a layered form and prevent particle detachment, the average particle size is preferably 150 µm or less, and more preferably 120 µm or less. When producing the thermal insulation layer, the average particle size can be 100 µm or less, considering the stability of a liquid composition and ease of application.The average particle size of the silicon oxide aerogel powder can be determined by the median diameter (D. 50 ) which is determined from a volume-based particle size distribution measured by a laser diffraction / scattering method.

[0037] To ensure the desired thermal insulation, the silicon dioxide aerogel powder content in the composition can be 65% by weight or more, based on 100% by weight of the composition's solids content. Preferably, the content is 70% by weight or more. The solids content refers to components obtained by excluding volatile substances such as organic solvents and water. Examples of components different from the silicon dioxide aerogel powder contained in the thermal insulator for a battery pack of the present disclosure include infrared shielding particles, inorganic fibers, dispersants, inorganic reinforcing particles, and flame retardants. A formulation is also conceivable that includes a binder to hold the structural components in place, preventing silicon dioxide aerogel particles from detaching.However, there is a risk that a binder could create a heat transfer pathway, and there is also a risk that the effect achieved by the pore structure of the silicon oxide aerogel powder could be inhibited. Therefore, it is preferred that the thermal insulator for a battery pack according to the present disclosure does not contain a binder that binds structural components, such as the silicon oxide aerogel powder. The other components are described below. [Infrared shielding particles]

[0038] Infrared shielding particles absorb heat from a heat source, re-emit it from the surface on the heat source side, and consequently block radiant heat from the heat source, thus contributing to improved thermal insulation, especially at high temperatures. The particle size of the infrared shielding particles is preferably relatively small to allow them to fill the gaps (cavities) between silicon oxide aerogel particles, prevent bonding between infrared shielding particles or with other components, and hinder the formation of a heat transfer path. However, if the particle size is too small, the particles are less likely to be exposed to infrared radiation, infrared scattering becomes insufficient, and consequently, it is difficult to achieve the radiant heat blocking effect.In this regard, the average particle size of the infrared shielding particles can be 0.3 µm or more and 22 µm or less. The shape of the infrared shielding particles is not specifically restricted and can be spherical, flat, or the like. Regarding the average particle size of the infrared shielding particles, the median diameter (D) can be determined according to the silicon oxide aerogel powder. 50 ), which is determined from a volume-based particle size distribution measured by a laser diffraction / scattering method, and if a commercially available product is used, catalogue values ​​can be used.

[0039] Examples of infrared shielding particles include particles of one type selected from silicon carbide, kaolinite, montmorillonite, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, tin oxide, zinc oxide, tantalum oxide, manganese ferrite, manganese oxide, nickel oxide, nickel, silver oxide, silver, bismuth oxide, carbon black, graphite, titanium, titanium iron oxide, zirconium, zirconium oxide, zirconium silicate, barium titanate, manganese dioxide, chromium oxide, titanium carbide, tungsten carbide, tungsten oxide, niobium oxide, indium tin oxide, and cerium oxide, or mixed particles of two or more types selected therefrom. Of these, it is preferred, with a view to improving the radiant heat blocking effect, that the infrared shielding particles include particles with high emissivity, with an emissivity of 0.6 or more in the infrared wavelength range.Examples of particles with high emissivity include silicon carbide, kaolinite, silicon nitride, mica, aluminum oxide, zirconium oxide, aluminum nitride, zirconium silicate, cerium oxide, boron carbide, manganese oxide, tin oxide, and iron oxide. Furthermore, to enhance the effect of blocking radiative heat by scattering incident infrared radiation, a form comprising particles with a high refractive index in the infrared wavelength range is also effective. For example, particles with a high refractive index of 2.0 or higher in the visible light wavelength range are preferred. Examples of particles with a high refractive index include silicon carbide, titanium oxide, zirconium oxide, silicon nitride, aluminum nitride, zinc oxide, tantalum oxide, tungsten oxide, niobium oxide, cerium oxide, manganese oxide, tin oxide, bismuth oxide, iron oxide, and barium titanate.

[0040] For example, silicon carbide, titanium oxide, silicon nitride, mica, aluminum oxide, aluminum nitride, boron carbide, iron oxide, magnesium oxide, and the like exhibit a relatively high specific heat and a high heat capacity, and consequently, the particles themselves do not heat up easily. In this respect, they also contribute to an improvement in the thermal insulation of the thermal insulator. Furthermore, they also exhibit high heat resistance, which also contributes to improving the heat resistance of the thermal insulator. Silicon carbide is particularly preferred because its thermal conductivity does not increase significantly even in a high-temperature atmosphere of approximately 500 to 800 °C. [Inorganic fibers]

[0041] Inorganic fibers are physically interlocked around the silicon oxide aerogel particles, improving the mechanical strength of the thermal insulator and preventing the silicon oxide aerogel particles from detaching. The type of inorganic fiber is not specifically limited, but ceramic fibers, such as glass fibers and aluminum oxide fibers, are preferred with regard to heat resistance and mechanical strength. To ensure both reinforcement and the prevention of heat transfer pathways, the length of the inorganic fibers is preferably 16 mm or less. [Dispersing agent]

[0042] In cases where a dispersant is used when the silicon dioxide aerogel is crushed, or when the liquid composition for the thermal insulation layer is generated, the dispersibility of the silicon dioxide aerogel powder can be improved. Preferred dispersants include a surfactant and a water-soluble oligomer with both polar and nonpolar components in the side chain. Examples of surfactants include ionic surfactants (a cationic surfactant, an anionic surfactant, an amphoteric surfactant) and non-ionic surfactants. For example, when an ionic surfactant is used, the viscosity of the composition itself can increase with a relatively small amount, improving the dispersion of materials such as...A silicon dioxide aerogel powder can be stabilized in the composition. Examples of ionic surfactants include sodium carboxymethylcellulose (CMC-Na), polycarboxylic acid amine salts, polycarboxylic acid ammonium salts, polycarboxylic acid sodium salts, and TEMPO-oxidized cellulose nanofibers (CNF-Na). When a non-ionic surfactant is used, materials such as a silicon dioxide aerogel powder are simply incorporated into the solvent during the preparation of a composition. Furthermore, if these materials aggregate or separate in the composition, it becomes easier to redisperse them, and the solvent is likely to be released during molding. Examples of non-ionic surfactants include polyethylene oxide (PEO) and polyvinyl alcohol (PVA). [Inorganic amplifying particles]

[0043] To improve the mechanical strength of the thermal insulator, inorganic reinforcing particles can be incorporated. The type of inorganic reinforcing particles is not specifically limited; for example, particles with relatively high hardness and specific surface area, such as precipitated silicon dioxide, gel silicon dioxide, quartz glass, wollastonite, potassium titanate, magnesium silicate, glass flakes, calcium carbonate, and barium sulfate, can be used. [Flame retardant]

[0044] A flame retardant can be added to the thermal insulator to impart flame retardancy. Conventionally known flame retardants, such as halogen-based, phosphorus-based, and metal hydroxide-based flame retardants, can be used. Considering environmental impact, it is preferable to use a phosphorus-based flame retardant. Examples of phosphorus-based flame retardants include ammonium polyphosphate, red phosphorus, and phosphate esters.Of these, a flame retardant that is insoluble in water or coated with a water-resistant resin is preferred, as it is less likely that the flame retardant will leak out even if the thermal insulator comes into contact with water during use, and, for example, ammonium polyphosphate and resin-coated ammonium polyphosphate are preferred. <Verfahren zur Herstellung eines thermischen Isolators für ein Batteriepack>

[0045] When the first form of the compression-molded component is produced as the first thermal insulator for a battery pack according to the present disclosure, the composition can be placed in a mold and pressed at a surface pressure of about 0.1 to 2.0 MPa while being heated at a temperature of about 100 to 160 °C. The thermal insulator for a battery pack according to the present disclosure can be composed of only one compression-molded component or can comprise a substrate supporting the compression-molded component and an outer body that encloses the compression-molded component. The substrate can be arranged on only one side of the thermal insulator in the thickness direction or can be arranged on both sides of the thermal insulator in a sandwich-like manner. Furthermore, the thermal insulator can be covered with a single substrate, and the substrate can be used as the outer body.An adhesive layer can be placed between the thermal insulator and the substrate. The adhesive layer may contain a flame retardant in addition to adhesive components.

[0046] When the second form of the thermal insulating layer is produced as the first thermal insulator for a battery pack according to the present disclosure, the composition can be applied to the substrate by brushing or using a coating machine, such as a blade coater, a doctor blade coater, a nozzle coater, a comma coater (registered trademark), and a roller coater, or by spraying. Alternatively, the production can be carried out by immersing a substrate in a composition or forming a composition on a substrate by a papermaking process. Drying can be carried out at a temperature of 80 to 180 °C for several minutes to several tens of minutes.

[0047] Examples of substrate materials include woven fabric, resin, paper, and sheet steel. Examples of fibers forming the woven fabric include glass fibers, rock wool, ceramic fibers, aluminum oxide fibers, silicon oxide fibers, carbon fibers, metal fibers, polyimide fibers, aramid fibers, and polyphenylene sulfide (PPS) fibers. Ceramic fibers include refractory ceramic fibers (RCF), polycrystalline aluminum oxide fibers (polycrystalline wool: PCW), and alkaline earth silicate (AES) fibers. Of these, AES fibers are considered safer because they are biodegradable. Examples of resins include polyethylene terephthalate (PET), polyimide, polyamide, and PPS. Examples of paper include pulp and composite materials made from pulp and magnesium silicate. Examples of steel sheets include Galvalume steel sheets (registered trademark), galvanized sheets, stainless steel (SUS) sheets, iron sheets, and titanium sheets.The form of the substrate is not specifically restricted, and examples include a woven fabric, a nonwoven fabric, a film, a sheet, or a layer or board. The substrate can be a single layer or a laminate, in which two or more layers of the same or different materials are laminated together.

[0048] For example, glass fabrics, woven fabrics and nonwovens made from inorganic fibers such as glass fibers and metal fibers, and fire-resistant insulating papers made as composites of pulp and magnesium silicate exhibit relatively low thermal conductivity and excellent dimensional stability, even in high-temperature atmospheres. Furthermore, the use of a fire-resistant substrate enhances safety even further. This substrate, offering very good heat resistance, can be made from glass fibers, rock wool, ceramic fibers, polyimide, PPS, or similar materials. Specific examples include glass fiber nonwovens, glass fabrics, aluminum-glass fabrics, AES wool paper, and polyimide fiber nonwovens.

[0049] The second thermal insulator for a battery pack according to the present disclosure can be produced using the silicon oxide aerogel prepared by the aforementioned sol formation, gelation, drying, and similar steps, without forming it into a powder. For example, a fibrous material can be added along with the formed sol in the gelation step. Adding the fibrous material enhances the thermal insulator. The fibrous material can be not only a filament-like material but also a woven material (corresponding to the aforementioned substrate), such as a nonwoven fabric or a woven fabric. If a woven fabric is used, a sol can be applied to the fabric, or the fabric can be immersed in a sol to form a gel. The fibrous material can be either an inorganic fiber or an organic fiber, or it can comprise both.If the fiber material is thread-like, it is dispersed within the thermal insulator and physically interlocked with the silicon dioxide aerogel, thus improving the mechanical strength of the thermal insulator. Furthermore, if the fiber material is woven, the woven structure and the silicon dioxide aerogel are bonded together, also improving the mechanical strength of the thermal insulator.

[0050] The specific surface area and pore volume of the silicon oxide aerogel forming the second thermal insulator for a battery pack of the present disclosure can be measured by the same method as the method for measuring the specific surface area and pore volume of the silicon oxide aerogel powder of the present disclosure described above. For example, the silicon oxide aerogel can be crushed and the nitrogen gas adsorption capacity of the collected powder can be measured. [Examples]

[0051] Next, the present revelation will be described in more detail with reference to examples. (1) Pore structure and compression recovery of a silicon oxide aerogel powder<Herstellung eines Siliziumoxidaerogel-Pulvers> [Example 1]

[0052] First, a tetrafunctional silane compound (tetramethoxysilane), a trifunctional silane compound (methyltrimethoxysilane), water, and methanol were stirred and mixed at room temperature (20 °C ± 5 °C). Acetic acid was then added as an acid catalyst, and the mixture was stirred for 10 minutes, during which time the silane compound hydrolyzed to form a sol (sol formation step). The mixing ratio of tetramethoxysilane and methyltrimethoxysilane was 10:90 (mass ratio). Next, methanol and tetramethylammonium hydroxide were added to the resulting sol as a basic catalyst, and the mixture was stirred for 1 minute. It was then allowed to stand in a closed container at room temperature for 1 hour. Finally, the sample was allowed to stand and solidify at 90 °C for 6 hours (heat treatment), and the sol was polycondensed to form a gel (gelation step).Methanol was then added to the gel at 40 °C, and the basic catalyst was removed from the gel (washing step). The washed gel was then dried at atmospheric pressure and 80 °C for 2 hours to produce a silicon oxide aerogel of Example 1 (drying step). [Example 2 and comparative examples 1 to 3]

[0053] Four types of silicon dioxide aerogels, namely Example 2 and Comparative Examples 1 to 3, were prepared in the same manner as in Example 1, except that the mixing ratio of a tetrafunctional silane compound (tetramethoxysilane) and a trifunctional silane compound (methyltrimethoxysilane) was changed. The mixing ratios of the silane compounds in the respective silicon dioxide aerogels are shown in Table 1 below. Furthermore, the prepared silicon dioxide aerogel was pulverized using a Henschel mixer and subjected to the following measurements. <Messung der spezifischen Oberfläche und des Porenvolumens>

[0054] The nitrogen gas adsorption capacity of the prepared silicon dioxide aerogel powder was measured at liquid nitrogen temperature (-196 °C), and the specific surface area and pore volume were determined based on the obtained adsorption isotherm. The nitrogen gas adsorption capacity was measured using an Autosorb iQ high-vacuum physisorption / chemisorption analyzer (available from Anton Paar) in the relative pressure range of 0.025 to 0.995. The specific surface area was determined by a BET multi-point method using the nitrogen gas adsorption capacity value in a relative pressure range of 0.1 to 0.3. The pore volumes at relative pressures of 0.93, 0.965, and 0.99 were determined by a BJH method using the respective nitrogen gas adsorption capacities. The silicon dioxide aerogel powder sample was degassed prior to measurement as follows.First, the sample was placed in a drying oven and held at 117 °C for 3 hours. Next, the sample was placed in the measuring device and degassed at reduced pressure at 120 °C for 2 hours.

[0055] The Fig. Figure 1 shows adsorption isotherms of silicon dioxide aerogel powders for examples and comparisons. Furthermore, Table 1 shows the specific surface areas and pore volumes of the silicon dioxide aerogel powders. [Table 1] Comparative example 1 Example 1 Example 2 Comparative example 2 Comparative example 3 Mixing ratio (mass ratio) Trifunctional silane compound 100 90 70 60 50 Tetrafunctional silane compound 0 10 30 40 50 Specific surface area [m²] 2 / G] 565 718 742 953 965 Pore ​​volume [mL / g] a: relative pressure 0.93 0,8 1,2 1,7 1,8 1,6 b: relative pressure 0.965 1,3 2,4 3,0 2,0 1,7 c: relative pressure 0.99 5,0 4,2 4,1 2,1 1,8 condition (i) a / c × 100 [%] 17 28 42 89 93 Determination ◯ ◯ ◯ × × condition (ii) b / c × 100 [%] 27 57 74 98 96 Determination × ◯ ◯ ◯ ◯ Evaluation results Thermal insulation × ◯ ◯ × × Compression reset ◯ ◯ ◯ × ×

[0056] As it is in the Fig. As shown in Figure 1, in the silicon dioxide aerogel powders of Examples 1 and 2 and Comparison Example 1, which had a relatively high content of the trifunctional silane compound, the pore volume (total pore volume) at a relative pressure of 0.99 was large, and the proportion of pores with a small pore diameter was reduced compared to the silicon dioxide aerogel powders of Comparison Examples 2 and 3. Furthermore, as shown in Table 1, the silicon dioxide aerogel powders of Examples 1 and 2 all met the requirements for specific surface area, pore volume at a relative pressure of 0.99, and conditions (i) and (ii). <Bewertung der Kompressionsrückstellung>

[0057] The compression recovery of the manufactured silicon oxide aerogel powder was measured using a compression device located in Fig. 2A to Fig. 2C is shown. Fig. Figure 2A is a schematic view showing the structure of an upper element and a lower element, which together form the compression device. Fig. Figure 2B is a schematic view showing a state of the device at maximum compression, and the Fig. 2C is a schematic view showing the state of the device after a release. As shown in the Fig. As shown in Figure 2A, a compression device 8 comprises an upper element 80 and a lower element 81. The upper element 80 is made of stainless steel and includes a disc-shaped base 800 and a cylindrical piston part 801, which is located in the central part of the base 800 and projects downwards. The diameter D1 of the base 800 is 50 mm and the diameter D2 of the piston part 801 is 11.3 mm. The length of the piston part 801 is 27 mm, which is identical to the depth L of a recess 810 in the lower element 81, which is described below. The lower element 81 is also made of stainless steel and has a cylindrical shape with the same diameter D1 as the base 800 of the upper element 80. The cylindrical recess 810, in which the piston part 801 is received, is formed in the central part of the lower element 81. The depth L of the recess 810 is 27 mm.

[0058] The procedure for measuring compression recovery is as follows. First, the prepared silicon dioxide aerogel powder was sieved through a stainless steel sieve with 125 µm openings, and the powder that passed through was sieved again through a stainless steel sieve with 75 µm openings. The powder with a particle size of 75 µm to 125 µm remaining on the sieve was used to measure the compression recovery. Next, the silicon dioxide aerogel powder was filled into the well 810 of the lower element 81 while the lower element 81 was tapped up and down. The amount of silicon dioxide aerogel powder filled was adjusted to a height of 13 mm ± 1 mm from the bottom of the well 810. Then, using a Tensilon universal material testing machine “RTF1350” (available from A&D Co., Ltd.), as indicated by the downward-pointing white arrow in the Fig. As shown in Figure 2B, the upper element 80 was moved downwards at a speed of 12 mm / min, and a silicon oxide aerogel powder 82 was compressed using the piston part 801 until the compressive stress reached 3.0 MPa. Then, as indicated by the upward-pointing white arrow in the Fig. As shown in Figure 2C, the upper element 80 was moved upwards at a speed of 12 mm / min until the compressive stress reached 0 MPa, and then released. This compression-release process was performed 10 times, and the recovery rate was calculated from the displacement of the fill level of the silicon oxide aerogel powder 82 during a tenth compression-release cycle.

[0059] The recovery rate was calculated using the following formula (I), where L2 (mm) is the fill level of the silicon oxide aerogel powder at a compressive stress of 3.0 MPa (see the Fig. 2B) and L1 (mm) is the fill level of the silicon oxide aerogel powder after unloading (see the Fig. 2C). Then, if the recovery rate was 25% or more, this was rated as satisfactory (indicated by ◯ in Table 1), and if the recovery rate was less than 25%, it was rated as unsatisfactory (indicated by × in Table 1). The compression recovery evaluation results for the respective silicon oxide aerogel powders are summarized in Table 1. Reset rate(%)=(L1−L2) / L1×100

[0060] Furthermore, the Fig. Figure 3 is a graph showing the relationship between compressibility and compressive stress in the tenth compression-release cycle. In the graph in the Fig. 3. The compressibility on the horizontal axis is the value calculated by the following formula (II). Compressibility (%) = Compression displacement (mm) of the silicon oxide aerogel powder / Filling height (mm) of the original (unloaded) silicon oxide aerogel powder × 100

[0061] As shown in Table 1, the silicon dioxide aerogel powders of Examples 1 and 2 were confirmed to have high compression recovery. In contrast, the silicon dioxide aerogel powders of Comparison Examples 2 and 3 had a small pore volume (total pore volume) at a relative pressure of 0.99 and also exhibited a large a / c value in condition (i) and a large proportion of pores with a small pore diameter, resulting in low elasticity and poor compression recovery. (2) Thermal insulation of the silicon oxide aerogel powder

[0062] The manufactured silicon oxide aerogel powder was molded to produce a sample of a thermal insulator, and its thermal insulation was evaluated. <Herstellung einer Probe eines thermischen Isolators> [Preparation of a composition]

[0063] First, water was weighed into a resin container, a surfactant (PEO) was added as a dispersant, and the mixture was stirred using an air-driven paddle stirrer at 800 rpm for 60 minutes, dissolving the surfactant in the water. After stirring was stopped, silicon carbide (SiC) powder was added as an infrared heat-shielding particle, and the mixture was stirred again at 800 rpm for 15 minutes. While stirring continued, a silicon oxide aerogel powder was added and fully wetted in the liquid. Then, glass fibers were added as inorganic fibers, and the mixture was stirred at 800 rpm for 30 minutes. Finally, the mixture was stirred again at 1000 rpm for 10 minutes. In this way, a composition was prepared that contained a silicon oxide aerogel powder with an average particle size (D). 50 The composition contained particles of 70 µm. It had a clay-like consistency, with aggregated granular materials of 5 mm or less in diameter. The silicon oxide aerogel powder content was 73.7 wt% based on 100 wt% of the composition's solids content. Similarly, the surfactant content was 2.9 wt%, the silicon carbide powder content was 15.1 wt%, and the glass fiber content was 8.3 wt%.

[0064] Details of materials other than the silicon oxide aerogel powder are as follows. Silicon carbide powder: "Fuji Random GC #4000" (available from Fuji Manufacturing Co., Ltd.), average particle size 5 µm. Surfactant: Polyethylene oxide "PEO-8" (available from Sumitomo Seika Chemicals Co., Ltd.), viscosity medium molecular weight 1.7 million to 2.2 million. Glass fibers: "ECS03-615" (available from Central Glass Fiber Co., Ltd.), length 3 mm, fiber diameter 9 µm. [Manufacturing a molded component]

[0065] The manufactured clay-like composition was molded as follows. First, a base was created by arranging a first spacer plate made of SUS (silicon dioxide) on a fiberglass paper backing. The first spacer plate was 7 mm thick and had a 150 mm square injection hole in its center. The manufactured composition was injected into the injection hole of the first spacer plate and formed into a square plate. The first spacer plate was then removed, the fiberglass paper backing was placed on top, and the second spacer plate was then placed on top of the fiberglass paper backing, creating a laminate consisting of "fiberglass paper / composition / fiberglass paper / second spacer plate".The second spacer plate was 6 mm thick and had a 150 mm square injection hole in the center, just like the first spacer plate. The molded compound was injected into the injection hole of the second spacer plate.

[0066] Separately, a first sheet material, 320 mm square and 5 mm thick, made of aluminum, and a second sheet material, also 320 mm square and 1 mm thick, made of aluminum, were produced. A number of grooves were formed on one surface of the first sheet material. The grooves, each 2.5 mm wide, 3 mm deep, and 200 mm long, were formed linearly parallel at 5 mm intervals. Punched holes, each with a diameter of 1 mm, were formed at 2 mm intervals throughout the second sheet material. The second sheet material was placed on one surface of the first, and the laminate was applied to its upper surface.The second sheet material was then placed on the laminate, and the first sheet material was additionally positioned on top such that the surface with the grooves faced the second sheet material. In this configuration, compression molding was performed by hot pressing at a temperature of 165 °C and a load of approximately 980 kN for 10 minutes. Cooling to room temperature was then carried out, and the first sheet material, the second sheet material, the second spacer plate, and the top and bottom layers of fiberglass paper were removed, resulting in a square, compression-molded sheet component with a thickness of 6 mm. The manufactured compression-molded component was used as a sample of a thermal insulator and, according to the silicon dioxide aerogel powder used, was designated as Sample of Example 1. <Bewertung der thermischen Isolierung>

[0067] The thermal conductivity of a thermal insulator sample at 600 °C was measured using a QTM-700 rapid thermal conductivity meter and a PD-31N high-temperature probe (available from Kyoto Electronics Manufacturing Co., Ltd.) as follows. First, the thermal insulator sample was laminated to produce two laminates, each approximately 20 mm thick. The laminate was applied to both the top and bottom surfaces of the probe, with the probe inserted. After this, a weight of approximately 5 kg, not heavy enough to damage the laminate, was placed on the top surface of the laminate in an electric oven. The temperature in the electric oven was then raised to 600 °C, stabilized, and the thermal conductivity was measured.In this example, if the measured thermal conductivity was less than 0.12 W / m·K, it was rated as satisfactory (indicated by ◯ in Table 1), and if the thermal conductivity was 0.12 W / m·K or more, it was rated as unsatisfactory (indicated by × in Table 1). The thermal insulation assessment results are summarized in Table 1.

[0068] As shown in Table 1, the samples from Examples 1 and 2 were confirmed to exhibit excellent thermal insulation. In contrast, the sample from Comparative Example 1 had a low b / c ratio under condition (ii) and a small number of pores with a pore diameter of up to approximately 68 nm, resulting in poor thermal insulation. Furthermore, the samples from Comparative Examples 2 and 3 had a b / c ratio within a desired range under condition (ii) and a small pore volume (total pore volume) at a relative pressure of 0.99, leading to reduced thermal insulation. In summary, the silicon oxide aerogel powders from Examples 1 and 2 were confirmed to exhibit excellent compression recovery, and the samples used in a thermal insulator showed excellent thermal insulation at high temperatures. Description of reference symbols

[0069] 8 ... Compression device, 80 ... Upper element, 800 ... Base, 801 ... Piston part, 81 ... Lower element, 810 ... Recess, 82 ... Silicon oxide aerogel powder QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-165387 A

[0003] JP 2023-27128 A

[0003]

Claims

[1] Silicon oxide aerogel powder used in a thermal insulator for a battery pack, characterized by , that when the silicon oxide aerogel powder is measured by a nitrogen adsorption quantity measurement method, a specific surface area and a pore volume at a relative pressure of 0.99, measured on the basis of a obtained adsorption isotherm, are 550 m² 2 / g or more or 3.5 mL / g or more and 5.0 mL / g or less, and if a [mL / g] is a pore volume at a relative pressure of 0.93, b [mL / g] is a pore volume at a relative pressure of 0.965, and c [mL / g] is a pore volume at a relative pressure of 0.99, the following conditions (i) and (ii) are satisfied: 0≤(a / c×100)≤50 50≤(b / c×100)<100. [2] Thermal insulator for a battery pack, wherein the thermal insulator comprises the silicon oxide aerogel powder according to claim 1. [3] Thermal insulator for a battery pack according to claim 2, wherein the thermal insulator comprises a molded component of a composition containing the silicon oxide aerogel powder. [4] Thermal insulator for a battery pack according to claim 2 or 3, wherein the thermal insulator further comprises at least one selected from infrared shielding particles, inorganic fibers and dispersing agents. [5] Thermal insulator for a battery pack according to any one of claims 2 to 4, wherein the silicon oxide aerogel powder has an average particle size of 30 µm or more and 150 µm or less. [6] Thermal insulator for a battery pack according to any one of claims 2 to 5, wherein the thermal insulator is used in a vehicle. [7] Thermal insulator for a battery pack, wherein the thermal insulator comprises a silicon oxide aerogel, characterized by, that when the silicon oxide aerogel powder is measured by a nitrogen adsorption quantity measurement method, a specific surface area and a pore volume at a relative pressure of 0.99, measured on the basis of a obtained adsorption isotherm, are 550 m² 2 / g or more or 3.5 mL / g or more and 5.0 mL / g or less, and if a [mL / g] is a pore volume at a relative pressure of 0.93, b [mL / g] is a pore volume at a relative pressure of 0.965, and c [mL / g] is a pore volume at a relative pressure of 0.99, the following conditions (i) and (ii) are satisfied: 0≤(a / c×100)≤50 50≤(b / c×100)<100. [8] Thermal insulator for a battery pack according to claim 7, wherein the thermal insulator further comprises at least one selected from infrared shielding particles and dispersing agents. [9] Thermal insulator for a battery pack according to claim 7 or 8, wherein the thermal insulator is used in a vehicle. [10] Thermal insulator for a battery pack according to any one of claims 7 to 9, wherein the thermal insulator further comprises a fiber material.

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