Thermal insulation material for electrochemical cells

Abstract

The invention relates to a thermal insulation material for electrochemical cells, preferably for lithium-ion cells, comprising a thermal insulation layer that includes a first fabric, said first fabric having a coating which contains aerogel particles and at least one binder that is at least partially water-soluble.

Description

[0001] Thermal insulation material for electrochemical cells

[0002] The invention relates to a thermal insulation material for electrochemical cells, in particular for lithium-ion cells, to an electrochemical cell, preferably a lithium-ion cell, which is thermally insulated by a thermal insulation material according to the invention, and to a cell module and / or a battery system in which at least two electrochemical cells are thermally insulated from one another by a thermal insulation material according to the invention. The invention further relates to methods for producing the thermal insulation material and its use.

[0003] Thermal insulation materials for preventing or at least delaying thermal runaway in electrochemical cells are known. Thermal runaway poses a high safety risk. Safety standards for lithium-ion batteries therefore also include a fire test. In this test, a cell in a battery module is subjected to thermal runaway, and then it is determined whether ignition occurs as a result of thermal spread to other cells. To reduce this risk, fire-resistant materials or thermal insulation materials—materials with high thermal insulation properties—are usually placed between the cells.

[0004] Conventional thermal insulation materials such as foam or fiberboard can withstand high temperatures but have relatively low thermal insulation capacity. Consequently, such materials require high insulation thickness to ensure effective thermal management. However, the space required for battery modules limits the space available for insulation between cells within the module. Refractory materials such as mica or ceramic boards can also withstand high temperatures, but are relatively incompressible and have low thermal insulation capacity. Such materials are therefore unsuitable for battery systems in which the cells expand and contract during operation, such as pouch and prismatic cells.It is also desirable to limit the overall weight of the battery module without compromising its resistance to heat propagation, fire propagation or mechanical properties.

[0005] To achieve good thermal insulation, it is also known to use aerogels, which exhibit very high insulating properties. Aerogels are a class of structures with low density, open cell structures, large surface areas, and pore sizes in the nanometer range. Their effectiveness is based on the fact that their low density causes heat conduction over long distances within the framework structure. Furthermore, the large pore volumes and very small pore sizes result in minimal convection. Aerogels can also be enriched with IR-absorbing or scattering dopants to increase their insulating properties. Typically, aerogel materials have a thermal resistance two to six times higher than other common types of insulation, e.g., foams, glass fibers, etc. For this reason, aerogels can increase effective shielding and thermal insulation without significantly increasing the thickness or weight of the insulation.

[0006] It would be desirable to obtain a thermal insulation material for the thermal management of electrochemical cells, especially lithium-ion batteries, that is suitable for the thermal insulation of individual cells, cell modules, and / or battery systems and that combines high thermal insulation capacity with low thickness and weight. For sustainability reasons, it would also be desirable for the thermal insulation material to be easily recyclable.

[0007] US 2012 / 0142802 A discloses open-cell foams partially filled with aerogel. US 2019 / 0161909 A by Oikawa discloses a thermal insulation panel comprising a nonwoven fabric and an aerogel. However, the materials described therein do not have the desired combination of thermal, fire-resistant, mechanical, and hydrophobic properties for use in battery thermal management elements. Furthermore, the materials are not easily recyclable. WO2021142169 A1 discloses a battery thermal management element comprising: a first thermal protection layer and at least one elastic layer containing one or more organic materials. The thermal protection layers can comprise an aerogel composition, which is preferably a silica aerogel composition. The aerogel composition can further contain a binder, with adhesives, resins, cements, foams, and polymers being mentioned as binders.The thermal management element is not easily recyclable.

[0008] From US 2021257690A1 an assembly for a battery is known, comprising a thermal management multilayer film arranged on a surface of an electrochemical cell, wherein the thermal management multilayer film comprises a thermally insulating layer, a first heat-distributing layer arranged on a first side of the thermally insulating layer, and a second heat-distributing layer arranged on a second side of the thermally insulating layer.

[0009] The thermally insulating layer can contain a nonwoven fabric, such as fiberglass, combined with an aerogel and a binder. Binders for the fiberglass layer include epoxy, a polyamide, a polyimide, a polyester such as poly(butylene terephthalate), a polyethylene, a polypropylene, a polystyrene, a polycarbonate, a polysulfone, a polyurethane, a silicone, and a vinyl ester. The layer is not easily recyclable.

[0010] Commercially available aerogel-based thermal insulation materials, such as the Aerogel Blanket (Type: SACB-0-6) from Tradematt (Henan) Industry or the Nasbis Insulation Sheet (EYGY0912Q.N3P) from Panasonic Industrial Devices, also have the disadvantage of generating dust. For this reason, the Nasbis Insulation Sheet is packaged, which, however, results in reduced compressibility. KR 2019 0143300 A describes an aerogel insulation composition comprising aerogel powder, a fibrous insulation material, and an organic-inorganic composite binder. The fibrous insulation material can consist of long fibers, short fibers, or a mixture of long fibers and short fibers. The aerogel insulation composition can be produced by mixing aerogel with the fibrous insulation material and an organic-inorganic binder. A fiber layer may be arranged as a support on one or both sides of the aerogel insulation composition.The fiber layer is comparatively thin (10-40 μm), which is detrimental to strength and compressibility. Furthermore, it is difficult to compensate for thickness variations in battery cells. Furthermore, the fibers within the binder layer reduce thermal insulation. Furthermore, long fibers have a negative impact on the recyclability of the insulation composition because they tend to entangle.

[0011] EP3281968 (A1) describes an aerogel-containing composition comprising an aerogel, a water-soluble binder, a propellant, and a solvent, wherein the solvent comprises water and a polar organic solvent. The composition preferably comprises fibers. The aerogel-containing composition can be applied to a carrier. Here, too, the fibers within the binder layer reduce thermal insulation. Furthermore, the propellant increases the fire hazard and / or is environmentally harmful.

[0012] The invention is based on the object of providing a thermal insulation material for the thermal management of electrochemical cells, in particular lithium-ion cells, cell modules, and / or battery systems, which is suitable for thermal insulation for the aforementioned products and can combine high thermal insulation capacity with low thickness and weight. Furthermore, the thermal insulation material should be easily recyclable and meet the requirements placed on electrochemical cells with regard to dynamic mechanical stability and thermal insulation capacity under compression. Further objects include the provision of methods for producing the thermal insulation material and uses thereof.This object is achieved by a thermal insulation material for electrochemical cells, preferably for lithium-ion cells, for cell modules and / or battery systems, comprising a thermally insulating layer which comprises a first textile fabric, wherein the first textile fabric has a coating which contains aerogel particles and at least one binder, wherein the binder is at least partially water-soluble.

[0013] The object is achieved in particular by a thermal insulation material for electrochemical cells, preferably for lithium-ion cells, for cell modules and / or battery systems, comprising a thermally insulating layer which comprises a first textile fabric, wherein the first textile fabric has a coating which contains aerogel particles and at least one binder, wherein the binder is at least partially water-soluble and wherein the first textile fabric has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm.

[0014] The thermal insulation material according to the invention is ideally suited for the thermal insulation of electrochemical cells, preferably lithium-ion cells, cell modules, and / or battery systems, demonstrating high thermal insulation properties even with low thickness and weight. Cell modules comprise at least two interconnected electrochemical cells but no battery management system.

[0015] Battery systems comprise at least one electrochemical cell and / or at least one cell module, as well as a battery management system. The thermal insulation material meets the requirements placed on electrochemical cells regarding dynamic mechanical stability and thermal insulation under compression.

[0016] Furthermore, the thermal insulation material is characterized by its good recyclability. This good recyclability is made possible by the fact that the thermal insulation material can be easily broken down into its components by adding it to water or other suitable solvents, for example, due to the at least partial water solubility of the binder. Due to their low density, the aerogel particles float on the surface of the water after the binder has dissolved and can be easily skimmed off, dried, and reused. A further advantage of the combination of aerogels and an at least partially water-soluble binder is the large surface area of ​​aerogels. This enables thin binder layers that can be dissolved particularly quickly by water.

[0017] The binder is advantageously at least partially water-soluble. Whether a binder is at least partially water-soluble according to the invention can be determined using the water solubility measurement described in the Measurement Methods chapter.

[0018] The proportion of the binder is preferably 3 wt.% to 25 wt.%, more preferably 3 wt.% to 20 wt.%, in particular 5 wt.% to 15 wt.%, in each case based on the total weight of the coating.

[0019] At least partially water-soluble binders may contain a single at least partially water-soluble polymer or a mixture of at least partially water-soluble polymers.

[0020] Preferably, the at least partially water-soluble binder is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amide, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof.

[0021] The at least partially water-soluble binder is particularly preferably selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyvinyl alcohol, polyacrylamide, cellulose-based binders, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch, and copolymers and blends thereof. Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyvinyl alcohol, polyacrylamide, cellulose-based binders, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch, and blends thereof.

[0022] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyacrylamide, cellulose-based binder, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch and blends thereof.

[0023] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol%, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch, hydroxypropylated starch and copolymers and blends thereof.

[0024] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch, hydroxypropylated starch and copolymers and blends thereof.

[0025] Furthermore, the at least partially water-soluble binder is particularly preferably selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol%, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch and hydroxypropylated

[0026] Starch and blends thereof.

[0027] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch and hydroxypropylated starch and blends thereof.

[0028] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol%, polyvinyl alcohol and copolymers and blends thereof.

[0029] Further particularly preferably, the at least partially water-soluble binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol%, polyvinyl alcohol and blends thereof.

[0030] In a further particularly preferred embodiment, the at least partially water-soluble binder is partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol% and / or polyvinyl alcohol.

[0031] In a further particularly preferred embodiment, the at least partially water-soluble binder is partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%.

[0032] The degree of saponification of polyvinyl acetate can be determined using IS K 6726, Issue 94, October 20, 2017. Polyvinyl alcohol (PVOH) is a synthetic polymer produced by the hydrolysis or saponification of polyvinyl acetate. PVOH can be produced by the complete hydrolysis or saponification of polyvinyl acetate by converting all acetate groups to alcohol groups. Polyvinyl alcohol can be considered a vinyl alcohol homopolymer. PVOH contains numerous hydrogen bonds and is a highly crystalline polymer that dissolves in hot water above approximately 60°C.

[0033] However, the hydrolysis of polyvinyl acetate can also be incomplete if a certain number of acetate groups remain. This then leads to the formation of partially saponified polyvinyl acetate. Partially saponified polyvinyl acetate has fewer hydrogen bonds than polyvinyl alcohol. The polymer is more weakly hydrogen-bonded, less crystalline, and soluble even in cold water. As such, partially saponified polyvinyl acetate can also be considered a vinyl alcohol-vinyl acetate copolymer. A preferred partially saponified polyvinyl acetate contains only vinyl alcohol and vinyl acetate groups.

[0034] The coating described here may contain one or more polyvinyl alcohols, one or more partially saponified polyvinyl acetates, or a combination thereof as binders. In a preferred embodiment, the binder contains polyvinyl alcohol and / or partially saponified polyvinyl acetate.

[0035] In some embodiments, the binder comprises a polyvinyl alcohol copolymer and / or a copolymer of a partially saponified polyvinyl acetate. Polyvinyl alcohol copolymers contain at least one additional monomer unit in addition to the vinyl alcohol groups.

[0036] Copolymers of partially saponified polyvinyl acetate contain at least one further monomer unit in addition to the vinyl alcohol groups and the vinyl acetate groups.

[0037] In one embodiment, the polyvinyl alcohol copolymer and / or the copolymer of partially saponified polyvinyl acetate comprises at least one neutral additional monomer unit, in particular ethylene, propylene, and / or N-vinylpyrrolidone. In a further embodiment, the polyvinyl alcohol copolymer and / or the copolymer of partially saponified polyvinyl acetate comprises at least one cationic additional monomer unit.

[0038] In a further embodiment, the polyvinyl alcohol copolymer and / or the copolymer of partially saponified polyvinyl acetate has at least one anionic further monomer unit, in particular vinyl polymerization units, sulfonic acid vinyl monomers and their esters, monocarboxylic acid vinyl monomers, their esters and anhydrides, dicarboxylic acid monomers with a polymerizable double bond, their esters, anhydrides and alkali metal salts of the aforementioned substances.

[0039] Examples of particularly suitable anionic further monomer units are the vinyl polymerization units corresponding to the anionic vinyl monomers including vinyl acetic acid, maleic acid, monoalkyl maleate, dialkyl maleate, maleic anhydride, fumaric acid, monoalkyl fumarate, dialkyl fumarate, itaconic acid, monoalkyl itaconate, dialkyl itaconate, citraconic acid, monoalkyl citraconic acid, dialkyl citraconic acid, citraconic anhydride, mesaconic acid, monoalkyl mesaconate, dialkyl mesaconate, glutaconic acid, monoalkyl glutaconate, dialkyl glutaconate, glutaconic anhydride, alkyl acrylates, alkyl alkacrylates, vinylsulfonic acid, sulfonic acid, allylsulfonic acid, ethylenesulfonic acid, 2-acrylamido-l-methylpropanesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-methylacrylamido-2-methylpropanesulfonic acid, 2-Sulfoethyl acrylate, alkali metal salts of the above (e.g. sodium, potassium or other alkali metal salts), esters of the above (e.g.Methyl, ethyl or other C1-C4 or C6 alkyl esters) and combinations of the above (e.g. several types of anionic monomers or equivalent forms of the same anionic monomer).

[0040] In some embodiments, the polyvinyl alcohol copolymer and / or the partially saponified polyvinyl acetate copolymer may contain two or more types of additional monomer units selected from neutral, anionic, and / or cationic monomer units. The coating described herein may contain one or more of the described polymers as binders.

[0041] In a preferred embodiment, the coating comprises at least one non-white dye. This is advantageous because the coating quality can be easily assessed visually.

[0042] More preferably, the first textile fabric comprises glass fibers with a diameter of 1 to 30 pm, more preferably 5 to 20 pm, even more preferably 7 to 18 pm, in particular 7 to 15 pm.

[0043] A further subject matter of the invention is a thermal insulation material for electrochemical cells, preferably for lithium-ion cells, for cell modules and / or battery systems, comprising a thermally insulating layer which comprises a first textile fabric, wherein the first textile fabric has a coating which contains aerogel particles and a binder, wherein the binder is preferably at least partially water-soluble and wherein the binder is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amide, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose,Gelatin and its salts, dextrin, maltodextrin and copolymers and blends thereof, wherein the first textile fabric preferably has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 0.2 mm to 3.0 mm.

[0044] Preferred binders of the thermal insulation material correspond to those described above with respect to the at least partially water-soluble binder.

[0045] Thus, the binder is preferably selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amide, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof.

[0046] More preferably, the binder is preferably selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amide, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof.

[0047] Further particularly preferably, the binder is selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyacrylamide, cellulose-based binder, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch and blends thereof.

[0048] Further particularly preferably, the binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch, hydroxypropylated starch and blends thereof.

[0049] In a further particularly preferred embodiment, the binder is partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%.In a preferred embodiment of the invention, the coating comprises a binder which is at least partially water-soluble according to the method defined in the description and / or a binder which is preferably at least partially water-soluble and is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and blends thereof in an amount of 3 wt.% to 25 wt.%, preferably 3 wt.% to 20 wt.%, in particular of 5 wt% to 15 wt%%, each based on the total weight of the coating.

[0050] In a further preferred embodiment, the thermal insulation material according to the invention contains no water-insoluble binder or contains water-insoluble binder only in an amount of less than 10 wt.%, preferably less than 7.5 wt.%, in particular less than 5 wt.%, based on the total weight of the coating. The water-insoluble binder is preferably a binder that is at least partially water-insoluble according to the method defined in the description. The advantage of this is its improved recyclability.

[0051] In a further preferred embodiment, the thermal insulation material according to the invention does not comprise a water-insoluble binder or comprises a water-insoluble binder selected from inorganic binders, in particular from water glass, silica sol, cement, clay minerals and / or phosphorus-containing binders, for example as phosphate, only in an amount of less than 10 wt.%, preferably less than 7.5 wt.%, in particular less than 5 wt.%, based on the total weight of the coating.

[0052] In a further preferred embodiment, the inventive

[0053] Thermal insulation material does not contain any inorganic binder or inorganic binder only in an amount of less than 1 wt.%, preferably less than 0.5 wt.%, in particular less than 0.1 wt.%, based on the total weight of the coating.

[0054] In a further preferred embodiment, the thermal insulation material according to the invention does not comprise a blowing agent, for example selected from saturated hydrocarbons having 1-8 carbon atoms, halogenated hydrocarbons having 1-8 carbon atoms and carbon dioxide, or blowing agent, for example selected from saturated hydrocarbons having 1-8 carbon atoms, halogenated hydrocarbons having 1-8 carbon atoms and carbon dioxide, only in an amount of less than 1 wt.%, preferably less than 0.5 wt.%, in particular less than 0.1 wt.%, based on the total weight of the coating.

[0055] In a preferred embodiment of the invention, the coating contains no fibers that are not part of the textile fabric, or fibers that are not part of the textile fabric only in a proportion of less than 5 wt.%, more preferably less than 2.5 wt.%, based on the total weight of the coating. This is advantageous in its lower thermal conductivity. Fibers that are not part of the textile fabric do not touch the textile fabric in the uncompressed state of the thermal insulation material.

[0056] More preferably, the coating is made from a precursor material which does not contain any fibers, or fibers only in a proportion of less than 5 wt.%, more preferably less than 2.5 wt.%, based on the total weight of the precursor material.

[0057] The aerogel particles preferably comprise inorganic, organic or inorganic-organic hybrid materials.

[0058] In principle, all metal oxides, polymers, and some other materials can be used as starting materials for aerogel synthesis using a sol-gel process. Aerogels can be produced by drying a gel from a gel-like substance, preferably silica, under extreme conditions. Aerogels in the broader sense, i.e., "gel with air as a dispersant," are produced by drying a suitable gel. The term "aerogel" in this sense includes, among others, aerogels in the narrower sense and xerogels. A dried gel is referred to as an aerogel in the narrower sense if the liquid of the gel is removed at temperatures above the critical temperature and starting from pressures above the critical pressure. The advantage of this is that these special drying conditions ensure dimensional stability.

[0059] If, however, the liquid of the gel is removed subcritically, for example, with the formation of a liquid-vapor interface, the resulting gel is referred to as a xerogel. According to the invention, aerogels that are not dried under critical conditions can also be used. With this procedure, dimensional stability can be maintained during the drying process by functionalizing, preferably silanizing, the gel precursor surface (functionalized aerogels). The advantage of functionalized aerogels is that they can be made hydrophobic through functionalization and thus absorb less moisture during use. Furthermore, they are more cost-effective than aerogels in the narrower sense because they can be produced continuously.

[0060] It should be noted that the aerogels according to the invention are aerogels in the sense of a gel with air as a dispersant, i.e., aerogels in the broader sense. The shaping process of the aerogel is usually completed during the sol-gel transition. After the solid gel structure has formed, the external shape can usually only be changed by comminution, for example, grinding, since the material is too brittle for any other form of processing.

[0061] Preferred aerogel particles are made of silica.

[0062] The aerogel particles preferably have a particle size distribution with a d50 value of 50 μm to 3 mm, more preferably from 200 μm to 3 mm, and / or a d95 value of 50 μm to 10 mm, even more preferably from 500 μm to 5 mm, and in particular from 750 to 2.5 mm. In a further preferred embodiment, the aerogel particles preferably have a particle size distribution with a d50 value of 5 μm to 300 μm, even more preferably from 5 μm to 150 μm, and / or a d95 value of 5 μm to 750 μm, even more preferably from 5 μm to 500 μm, and in particular from 5 μm to 500 μm. The particle size distribution is measured according to DIN 66165-2:2016-08.

[0063] The coating preferably has a proportion of aerogel parti no of at least 60 wt.%, for example from 60 to 95 wt.%, more preferably from 60 to 90 wt.%, even more preferably from 60 to 85 wt.% and in particular from 60 to 80 wt.%, in each case based on the total weight of the coating.

[0064] The thermal insulation material also preferably has a proportion of aerogel parti kein of 6 to 75 wt.%, more preferably of 10 to 70 wt.%, more preferably of 10 to 60 wt.%, more preferably of 15 to 55%, in each case based on the total weight of the thermal insulation material.

[0065] According to the invention, the thermal insulation material comprises a first textile fabric having a coating containing aerogel particles and a binder. A coating is understood to mean that the aerogel particles and the binder at least partially cover at least one surface of the first textile fabric. The coating can also have penetrated at least partially into the first textile fabric. The coating can therefore also be present at least partially as an impregnation. The coating can be present on one or both surfaces of the first textile fabric. Preferably, it is present on only one surface, since the textile fabric can thus offer mechanical protection on the side facing away from the coating and / or function as an adhesive aid.

[0066] In a further preferred embodiment, the thermal insulation material comprises at least a second textile fabric. The second textile fabric can function as a protective layer. In a preferred embodiment, the second textile fabric is arranged on the side of the coating facing away from the first textile fabric. In this way, the textile fabrics provide mechanical protection on both sides of the coating. The coating can also be at least partially penetrated into the second textile fabric. The coating can therefore also be present at least partially as an impregnation in the second textile fabric. This offers the advantage of even better particle integration, since the particles can be "wedged" in the interfiber spaces.

[0067] The second textile fabric is also preferably located at least partially outside the coating. This allows it to protect the thermal insulation material from mechanical stress.

[0068] If the thermal insulation material does not comprise any further textile fabric in addition to the first textile fabric, the proportion of aerogel parti is preferably at most 75% by weight, for example from 10 to 75% by weight, more preferably from 10 to 65% by weight, more preferably from 15 to 65% by weight, more preferably from 15 to 55% by weight, in each case based on the total weight of the thermal insulation material.

[0069] If the thermal insulation material comprises a second textile fabric and / or further textile fabrics in addition to the first textile fabric, the proportion of aerogel parti is preferably at least 6 wt.%, for example from 6 to 60 wt.%, more preferably from 10 to 60 wt.%, more preferably from 10 to 55 wt.%, more preferably from 15 to 45 wt.%, in each case based on the total weight of the thermal insulation material.

[0070] The coating may also contain one or more additional additives, such as fire-retardant additives, particularly additives based on organic nitrogen and / or phosphorus compounds. These are particularly advantageous because, in addition to their fire-retardant effect, they also have a plasticizing and thus flexibilizing effect on polymers.

[0071] The coating may also contain wetting agents, for example to enable aqueous coating formulations with incompatible hydrophobic aerogels, rheology-modifying additives such as acrylates, acrylamides, cellulosic systems, dispersing aids, dyes and / or defoamers. In a preferred embodiment of the invention, the first and / or the second textile fabric is a nonwoven fabric. A nonwoven fabric is a structure made of fibers of limited length (staple fibers), continuous fibers (filaments) or cut yarns of any type and of any origin, which have been combined in some way to form a nonwoven fabric (a fiber layer, a fiber batt) and bonded to one another in some way; this excludes the crossing or entanglement of yarns, as occurs in weaving, knitting, lace making, braiding and the production of tufted products.Films and papers are not considered nonwovens. Nonwovens are defined in the standard DIN 61210-2:1988-10.

[0072] Preferably, the first and / or second textile fabric is a wet-laid nonwoven fabric. This is advantageous in that wet-laid nonwoven fabrics exhibit high isotropy and uniformity. In a further preferred embodiment, the first and / or second textile fabric is a nonwoven fabric, in particular a wet-laid nonwoven fabric, made of fibers with a staple length of 0.5 to 20 mm, more preferably 2 to 20 mm, more preferably 5 to 20 mm, even more preferably 5 to 18 mm, in particular 8 to 15 mm. Preferably, the first and / or the second textile fabric is a nonwoven fabric, in particular a wet-laid nonwoven fabric, which contains fibers with a staple length of 0.5 to 20 mm, more preferably of 2 to 20 mm, more preferably of 5 to 20 mm, more preferably of 5 to 18 mm, in particular of 8 to 15 mm in a proportion of at least 50 wt.%, more preferably of at least 70 wt.%, more preferably of at least 80 wt.%, more preferably of at least 90 wt.%, and in particular 100% by weight, in each case based on the total amount of fibres in the textile fabric.

[0073] The advantage of shorter fibers is that they are easier to recycle because they are less prone to entanglement. The diameter of the fibers is preferably from 1 to 30 pm, more preferably from 5 to 20 pm, even more preferably from 7 to 18 pm, especially from 7 to 15 pm.

[0074] Likewise preferably, the first and / or second textile fabric is a nonwoven, in particular a wet-laid nonwoven, which is bonded with a binder, in particular with an at least partially water-soluble binder. The water solubility of the binder can be determined analogously to that of the binder, as described in the chapter "Measurement Methods." Preferably, the binder, in particular the at least partially water-soluble binder, is selected from the polymers described according to the invention with reference to the at least partially water-soluble binder.

[0075] In one embodiment, the binder is preferably at least partially water-soluble and selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and blends thereof.

[0076] In a further embodiment, the binder is preferably at least partially water-soluble and selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyacrylamide, cellulose-based binder, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch and blends thereof.

[0077] In a further embodiment, the binder is preferably at least partially water-soluble and selected from the group consisting of polyvinyl acetate, partially saponified polyvinyl acetate, polyacrylamide, cellulose-based binder, preferably methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and chemically modified starch, in particular ethoxylated starch, hydroxypropylated starch and blends thereof.

[0078] In a further embodiment, the binder is preferably at least partially water-soluble and selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification of at least 50 mol%, for example 50 to 95 mol%, in particular 70 to 95 mol%, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch and hydroxypropylated starch and blends thereof.

[0079] In a further preferred embodiment of the invention, the first and / or the second textile fabric contains glass fibers. Preferably, both the first and the second textile fabric contain glass fibers. The advantage of using glass fibers is that, due to their high density, they sink to the bottom during the recycling process and can thus be easily separated from the lighter aerogel parts. The proportion of glass fibers, based on the total weight of the thermal insulation material, is preferably 25 to 94 wt.%, more preferably 35 to 85 wt.%, even more preferably 40 to 75 wt.%, and in particular 50 to 65 wt.%. Further preferably, the proportion of glass fibers in the first textile fabric, based on the total weight of the first textile fabric, is 60 to 98 wt.%, even more preferably 70 to 95 wt.%, and in particular 80 to 95 wt.%.More preferably, the proportion of glass fibers in the second textile fabric, based on the total weight of the second textile fabric, is 60 to 98 wt.%, even more preferably from 70 to 95 wt.% and in particular from 80 to 95 wt.%.

[0080] The glass fibers are preferably staple fibers, preferably with an average fiber length of 2 to 20 mm, more preferably 5 to 18 mm, in particular 8 to 15 mm. The diameter of the glass fibers is preferably 1 to 30 μm, more preferably 5 to 20 μm, in particular 7 to 15 μm. The glass fibers of the aforementioned staples can be used independently of one another for the first and / or second textile fabric.

[0081] In a preferred embodiment of the invention, the first textile fabric is a nonwoven fabric, preferably a wet-laid nonwoven fabric. In a further preferred embodiment of the invention, the second textile fabric is a nonwoven fabric, preferably a wet-laid nonwoven fabric.

[0082] The first and second textile fabrics can, independently of one another, also comprise fibers that are not glass fibers, in particular binding fibers and / or at least partially water-soluble fibers. Preferred binding fibers and / or at least partially water-soluble fibers are polyvinyl alcohol fibers and / or polyvinyl acetate fibers in which the polyvinyl acetate is partially saponified, preferably with a degree of saponification of at least 50 mol%, for example 50 to 100 mol%, in particular 70 to 100 mol%. A measurement to determine whether fibers are at least partially water-soluble is described in the "Measurement Methods" chapter.

[0083] If present, the proportion of fibers that are not glass fibers, in particular of the at least partially water-soluble fibers, in the first textile fabric, based on the total weight of the first textile fabric, is from 40 to 2 wt.%, more preferably from 30 to 4 wt.%, even more preferably from 25 to 5 wt.%, in particular from 15 to 5 wt.%. If present, the proportion of fibers that are not glass fibers, in particular of the at least partially water-soluble fibers, in the second textile fabric, based on the total weight of the second textile fabric, is from 40 to 2 wt.%, more preferably from 30 to 4 wt.%, even more preferably from 25 to 5 wt.%, in particular from 15 to 5 wt.%.

[0084] In one embodiment, the first and second textile fabrics independently contain both glass fibers and non-glass fibers in combination.

[0085] At least partially water-soluble fibers may contain a single at least partially water-soluble polymer or a mixture of at least partially water-soluble polymers. Preferred non-glass fibers are fibers containing at least one polymer as described with respect to the at least partially water-soluble binder.

[0086] Preferably, the first textile fabric has a basis weight measured according to ISO 9073-1:1989-07 in the range of 30 g / m 2 up to 300 g / m 2 , more preferably in the range of 40 g / m 2 up to 300 g / m 2 , especially in the range of 50 g / m 2 up to 250 g / m 2 The advantage of this is that the first textile fabric has sufficient coverage to ensure good fiber-coating interaction and also has sufficient strength for further processing.

[0087] Likewise, the first textile fabric preferably has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 0.2 mm to 3.0 mm, more preferably in the range of 0.3 mm to 2.5 mm, in particular in the range of 0.5 mm to 2.0 mm. An advantage of textile fabrics with a relatively low thickness is that they require little space. Furthermore, this allows the thermal insulation material to contain a relatively large amount of aerogel while maintaining a low overall thickness.

[0088] The advantage of textile fabrics with a rather higher thickness is that they are compressible, have higher strength and can compensate for thickness variations of battery cells.

[0089] In a further preferred embodiment of the invention, the coating is one that has been applied to the first textile fabric from a preferably aqueous dispersion. The dispersion preferably has a solids content in the range of 10 to 30 wt.%, more preferably 15 to 25 wt.%. This has the advantage that a relatively small amount of solids can be applied at low viscosities with a relatively small amount of liquid phase.

[0090] In one embodiment, the coating is made from a, preferably aqueous, dispersion which contains no fibers, or fibers only in a proportion of less than 2 wt.%, more preferably less than 1 wt.%, in particular less than 0.5 wt.%, based on the total weight of the dispersion.

[0091] Preferably, the second textile fabric has a basis weight in the range of 30 g / m 2 up to 300 g / m 2 , more preferably in the range 40 g / m2 up to 300 g / m 2 , especially in the 50 g / m range 2 up to 250 g / m 2 The advantage here is that the textile fabric has sufficient coverage to ensure good fiber-coating interaction and also has sufficient strength for further processing. The second textile fabric also preferably has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm, preferably in the range from 0.3 mm to 2.5 mm, in particular in the range from 0.5 mm to 2.0 mm. The advantage of textile fabrics with a relatively low thickness is that they require little space. The advantage of textile fabrics with a relatively high thickness is that they are compressible and can compensate for thickness fluctuations in battery cells.

[0092] The second textile fabric preferably has a low maximum tensile strength measured according to DIN EN ISO 9073-18:2008-08 to ensure the flexibility of the protected thermal insulation material. The maximum tensile strength of the second textile fabric is preferably in the range of 5 to 80 N / 5 cm, preferably in the range of 10 to 70 N / 5 cm, and particularly preferably in the range of 15 to 60 N / 5 cm.

[0093] In a further preferred embodiment of the invention, the second textile fabric has a tensile strength, measured according to DIN EN ISO 9073-18:2008-08, at 1 percent elongation of 2 to 60 N / 5cm, preferably in the range of 3 to 50 N / 5cm, more preferably 5 to 45 N / 5cm, even more preferably 10 to 45 N / 5cm, and especially 10 to 30 N / 5cm. The advantage of this is that the strength is low at low elongations, so that the material retains a certain degree of flexibility.

[0094] The first textile fabric preferably has a maximum tensile strength, measured according to DIN EN ISO 9073-18:2008-08, of at least 30 N / 5cm, preferably in the range of 30 to 1000 N / 5cm, more preferably 30 to 800 N / 5cm, even more preferably 30 to 400 N / 5cm, even more preferably 30 to 200 N / 5cm, in particular 30 to 100 N / 5cm. The advantage of these minimum tensile strengths is that they provide the thermal insulation material with sufficient strength for processing.

[0095] In a further embodiment of the invention, the thermal insulation material and / or the coating does not comprise a water-insoluble binder or comprises a water-insoluble binder only in an amount of less than 10 wt.%, preferably less than 7.5 wt.%, in particular less than 5 wt.%, based on the total weight of the coating, wherein the water-insoluble binder is preferably a binder which is not water-soluble according to the method defined in the description.

[0096] More preferably, the coating is made from a precursor material that does not contain a water-insoluble binder or contains water-insoluble binder only in an amount of less than 10 wt.%, preferably less than 7.5 wt.%, in particular less than 5 wt.%, based on the total weight of the precursor material, wherein the water-insoluble binder is preferably a binder that is not water-soluble according to the method defined in the description

[0097] In a further embodiment of the invention, the thermal insulation material has a flame-retardant layer, which preferably contains phyllosilicates, in particular mica. The flame-retardant layer preferably has a weight, measured according to ISO 9073-1:1989-07, of at least 50 g / m 2 , preferably from 60 to 500 g / m 2 , more preferably from 60 to 300 g / m 2 , especially from 70 to 150 g / m 2Particularly preferably, the flame-retardant layer is arranged in the thermal insulation material such that it represents at least one outer surface of the thermal insulation material.

[0098] In a further embodiment of the invention, the thermal insulation material comprises an IR-reflecting layer. The IR-reflecting layer is preferably arranged in the thermal insulation material such that it forms at least one outer surface of the thermal insulation material.

[0099] In a further preferred embodiment, the coating and / or the thermal insulation material has an air permeability (delta p), measured according to DIN EN ISO 9237:1995-12 at 100 Pa of at least 50 l / m 2 s, for example 100 l / m 2 s up to 600 l / m 2 s, preferably 200 l / m 2 s up to 500 l / m 2 s and especially 300 l / m 2 s up to 400 l / m 2s. More preferably, the coating and / or the thermal insulation material has an air permeability (delta p), measured according to DIN EN ISO 9237:1995-12 at 200 Pa, of at least 100 l / m 2 s, for example 300 l / m 2 s up to 900 l / m 2 s, preferably 400 l / m 2 s up to 800 l / m 2 s and especially 500 l / m 2 s up to 700 l / m 2 s. The advantage of these air permeabilities is that they allow cooling of the thermal insulation material through air convection. This type of cooling is particularly efficient when the thermal insulation material has not yet been compressed by the operation of the electrochemical cell.

[0100] In a further preferred embodiment, the coating and / or the thermal insulation material has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 1 mm to 9 mm, or 0.6 mm to 9 mm, preferably in the range of 1.2 mm to 6 mm, or 0.6 mm to 6 mm, more preferably in the range of 1.3 mm to 4 mm or 0.6 mm to 4 mm, and in particular in the range of 1.3 mm to 3 mm or 0.6 mm to 3 mm. If the thickness is less than 4 mm and in particular less than 3 mm, the space requirement is particularly low.

[0101] In a further preferred embodiment, the thermal insulation material has a basis weight in the range of 60 g / m 2 up to 900 g / m 2 , preferably 70 g / m 2 up to 600 g / m 2 , more preferably in the range of 80 g / m 2 up to 400 g / m 2 and especially in the range of 80 to 200 g / m 2 This low weight is advantageous for applications in electrochemical cells.

[0102] More preferably, the thermal insulation material has a recyclability, measured as described in the section on measurement methods, of grade 1, 2 or 3.

[0103] More preferably, the thermal insulation material has a thermal conductivity under compressive load of 20 kPa, measured according to ASTM D 5470-17, of 0.045 to 0.010 W / m*K, even more preferably of 0.040 to 0.010 W / m*K, and in particular of 0.036 to 0.010 W / m*K. More preferably, the thermal insulation material has a thermal conductivity under compressive load of 2059 kPa, measured according to ASTM D 5470-17, of 0.035 to 0.010 W / m*K, even more preferably of 0.030 to 0.010 W / m*K, and in particular of 0.027 to 0.010 W / m*K.

[0104] In a particularly preferred embodiment, the thermal insulation material is a thermal insulation material for electrochemical cells, preferably for lithium-ion cells, comprising a thermally insulating layer comprising a first textile fabric, wherein the first textile fabric has a coating containing aerogel particles and at least one binder selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonic acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof,wherein the first textile fabric preferably has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 0.2 mm to 3.0 mm.,

[0105] Preferred embodiments for the aforementioned thermal insulation material are those mentioned above and below. For example, the binder is preferably at least partially water-soluble. Furthermore, the first textile fabric is preferably a wet-laid nonwoven.Likewise preferably, the first textile fabric is a nonwoven fabric, preferably a wet-laid nonwoven fabric, which is bound with a binder selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and blends thereof.

[0106] A further subject of the invention is an electrochemical cell, preferably a lithium-ion cell, which is thermally insulated by at least one thermal insulation material according to the invention.

[0107] The invention further relates to a battery system in which at least one electrochemical cell, preferably at least one lithium-ion cell, is thermally insulated by at least one thermal insulation material according to the invention. The invention further relates to a cell module and / or a battery system in which at least two electrochemical cells are thermally insulated from one another by at least one thermal insulation material.

[0108] Another subject of the invention is a process for recycling a thermal insulation material according to the invention, comprising the following steps: a1) a thermal insulation material according to the invention is comminuted and introduced into a solvent, preferably water, a2) it is stirred and optionally heated, a3) the aerogel particles and the fibers of the textile fabric are separated from one another.

[0109] The solvent used is preferably one that at least partially dissolves the binder. The preferred solvent is water.

[0110] The method preferably recycles thermal insulation materials according to one or more of the embodiments described herein. Thus, preferred embodiments for the thermal insulation material recycled by the method include the embodiments mentioned above and below.

[0111] Another object of the invention is a method for producing a thermal insulation material for electrochemical cells comprising the following steps:

[0112] 1. Providing a first textile fabric, preferably with a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 0.2 mm to 3.0 mm,

[0113] 2. Coating the textile fabric with a dispersion containing aerogel particles and a binder, wherein the binder a) is at least partially water-soluble according to the method defined in the description, and / or wherein the binder

[0114] TI b) is preferably at least partially water-soluble according to the method defined in the description and wherein the binder is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof;

[0115] 3. Drying the resulting coating to form a heat-insulating layer.

[0116] Another object of the invention is a method for producing a thermal insulation material for electrochemical cells comprising the following steps:

[0117] 1. Providing a first textile fabric, preferably with a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range of 0.2 mm to 3.0 mm,

[0118] 2. Coating the textile fabric with a dispersion containing aerogel particles and a binder, wherein the binder is at least partially water-soluble according to the method defined in the description.

[0119] 3. Drying the resulting coating to form a heat-insulating layer.

[0120] Preferred embodiments of the processes according to the invention comprise preferred embodiments of the thermal insulation material according to the invention mutatis mutandis. Thus, the processes according to the invention are preferably used to produce thermal insulation materials according to one or more of the embodiments described above and below. Thus, in a preferred embodiment, in a step 2a following step 2, the thermally insulating layer is provided with at least one second textile fabric, which can function as a protective layer. The second textile fabric is preferably arranged on the side of the first textile fabric having the coating.

[0121] The dispersion may further contain wetting agents, for example to enable aqueous coating formulations with incompatible hydrophobic aerogels, rheology-modifying additives such as acrylates, acrylamides or cellulosic systems, dispersing aids, dyes and / or defoamers.

[0122] More preferably, the coating of the textile fabric in step 2 takes place in the form of a doctor blade coating.

[0123] A further object of the present invention is the use of the thermal insulation material according to the invention for heat management and / or for thermal insulation of electrochemical cells, preferably lithium-ion cells, cell modules and / or battery systems.

[0124] Preferred embodiments of the use according to the invention comprise preferred embodiments of the thermal insulation material according to the invention mutatis mutandis.

[0125] Measurement methods

[0126] Water solubility measurement binder:

[0127] Place 300 g of distilled water into a 500 ml Erlenmeier flask. Add 0.5 g of the dry binder, preferably with a particle size with a d90 value of 100 pm, measured according to DIN 66165-2:2016-08. The flask is placed in a laboratory shaker for 24 hours at 80°C. Ensure that the shaking frequency is selected such that the mixture is in motion, and any evaporating water is added. After 24 hours, the solid phase, if present, is quantitatively separated, preferably by filtering. The aqueous phase is evaporated to dryness. If no residue is obtained or the residue is less than 50 mg, the binder is not water-soluble. If the residue is obtained in an amount of at least 50 mg, the binder is at least partially water-soluble.

[0128] Water solubility measurement of fibers:

[0129] Place 300 g of distilled water into a 500 ml Erlenmeier flask. Then, add 0.5 g of the fiber. The flask is placed in a laboratory shaker at 80°C for 24 hours. Ensure that the shaking frequency is selected such that the mixture is agitated, and any evaporating water is added. After 24 hours, any solid phase present is quantitatively separated, preferably by filtering. The aqueous phase is evaporated to dryness. If no residue is obtained or the residue is less than 50 mg, the fiber is not water-soluble. If the residue is 50 mg or more, the fiber is at least partially water-soluble.

[0130] Determination of recyclability:

[0131] A DIN A4 sized sample of the material to be determined (sample 1) is taken and cut into small pieces (approximately 2 x 2 cm). These are placed in a 2000 ml beaker and the sample is mixed with 1000 ml of water. The water is brought to a boil while stirring vigorously and stirred for a further 60 minutes. The mixture is then allowed to cool to room temperature (23°C) while stirring and the phases are separated for a further 60 minutes. Once the separation has taken place, the aerogel particle slurry is skimmed off and the process is repeated two more times. The aerogel particle slurry is then transferred to a crystallization dish, dried at 120°C for 6 hours until constant weight is reached, and the mass is determined. If the difference between the mass of aerogel particle originally present in the sample and the mass determined in the test is less than 25%, the recyclability of the thermal insulation material is rated with a grade of 1.If the difference between the mass of aerogel parti no originally present in the sample and the mass determined by the test is 25% to 35%, the recyclability of the thermal insulation material is rated with a grade of 2. If the difference between the mass of aerogel parti no originally present in the sample and the mass determined by the test is 35% to 45%, the recyclability of the thermal insulation material is rated with a grade of 3. If the difference between the mass of aerogel parti no originally present in the sample and the mass determined by the test is more than 45%, the recyclability of the thermal insulation material is rated with a grade of 4.

[0132] The invention is explained in more detail below using non-limiting examples.

[0133] Production of Sample I:

[0134] In a 1000 ml beaker, 60 g of a 5% solution of distilled water and partially saponified polyvinyl acetate (Poval 5-74, Kuraray, saponification degree 74%) is placed. 0.2 g of a wetting agent based on a fatty alcohol ethoxylate (Rucogen D3, Rudolf Chemie) is added. 12 g of hydrophobic SiO2 aerogel particles with a particle size of 0.1–0.5 mm (Enova IC 3105, Cabot) are added in portions while stirring vigorously with a KPG stirrer. Once all particles have been incorporated, the resulting paste is applied to a wet-laid glass fleece with a surface weight of 60 g / m using a doctor blade. 2 applied and dried. The binder of the glass mat is the same as that used to bind the aerogel particles.

[0135] Production of Sample II:

[0136] Sample II is produced analogously to Sample I. After coating, another layer of glass fleece is applied to the still wet layer, lightly pressed down, and then dried.

[0137] Reference sample 1:

[0138] Airgel blanket: Type: SACB-0-6

[0139] Company: Tradematt (Henan) Industry,

[0140] Shenglong Plaza, Zhengdong New District, Zhenzhou China

[0141] Reference sample 2: Nasbis Insulation Sheet: EYGY0912Q.N3P (films included on the product were removed).

[0142] Company: Panasonic Industrial Devices

[0143] Two Riverfront Plaza

[0144] Newark, NJ 07102-5490

[0145] USA

[0146] Characteristics:

[0147] Dynamic mechanical stress test:

[0148] First, three round samples with a diameter of 25 mm are punched out, weighed, and placed between two pressure plates. They are then subjected to cyclic compression loading with the following parameters:

[0149] Climate: 23°C, 50% relative humidity

[0150] Pressure load: between the plates

[0151] Static pressure: 0.85 MPa

[0152] Dynamic pressure (vibration): + / - 0.65 Mpa

[0153] Frequency: 1 Hz

[0154] Number of cycles: 300

[0155] The loaded sample is then removed from the test fixture, weighed, and visually assessed. The visual assessment is performed by shaking the sample over a white piece of paper (in the case of colored particles) or a black piece of paper (in the case of white particles), and assessing whether any particles have detached from the coating. In the case of a laminate, the interlayer adhesion is also assessed.

[0156] Evaluation:

[0157] Conclusion:

[0158] After the described dynamic loading, the three measurements on Sample I show no decomposition in the sense of aerogel particles precipitating. In the case of the layer additionally protected by an additional nonwoven fabric (three measurements on Sample II), the thermal insulation material shows no delamination and no aerogel particles precipitating. Reference Sample 1 already shows aerogel dust during assembly of the test specimens and, after loading, aerogel particles appear more frequently on the test plate and in the shake test. Reference Sample 2 shows aerogel particles in the shake test.

[0159] Measurement of thermal conductivity

[0160] The thermal conductivity under pressure is measured according to ASTM D 5470-17 and gives the following results:

[0161] Conclusion:

[0162] Samples 1 and 2 according to the invention provide lower thermal conductivity coefficients over the entire pressure range and thus have better insulation properties.

[0163] Recyclability

[0164] Using the above-mentioned method, the recyclability of Sample 1 was determined and rated with a grade of 1. Reference Sample 1 was rated with a grade of 4.

Claims

Patent claims Thermal insulation material for electrochemical cells, preferably for lithium-ion cells, comprising a thermally insulating layer comprising a first textile fabric, wherein the first textile fabric has a coating containing aerogel particles and at least one binder, wherein the binder is at least partially water-soluble according to the method defined in the description, characterized in that the first textile fabric has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm. Thermal insulation material for electrochemical cells, preferably for lithium-ion cells, comprising a thermally insulating layer comprising a first textile fabric, wherein the first textile fabric has a coating containing aerogel particles and at least one binder, characterized in thatthat the binder is preferably at least partially water-soluble and is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof, wherein the first textile fabric preferably has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm. Thermal insulation material according to claim 1 or 2, characterized in that the binder is selected from the group consisting of partially saponified polyvinyl acetate,preferably with a degree of saponification according to IS K 6726, Issue 94, October 20, 2017 of at least 50 mol%, for example 50 to 100 mol%, preferably 70 to 100, mol%, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, ethoxylated starch and hydroxypropylated starch as well as copolymers and blends thereof. Thermal insulation material according to one or more of the preceding claims, characterized in that the binder is selected from the group consisting of partially saponified polyvinyl acetate, preferably with a degree of saponification according to IS K 6726, Issue 94, October 20, 2017 of at least 50 mol%, for example 50 to 95 mol%, preferably 70 to 95 mol%, as well as copolymers and blends thereof. Thermal insulation material according to one or more of the preceding claims, characterized in that the coating has at least partially penetrated into the first textile fabric.Thermal insulation material according to one or more of the preceding claims, characterized in that the thermal insulation material has at least a second textile fabric arranged on a side of the coating facing away from the first textile fabric. Thermal insulation material according to one or more of the preceding claims, characterized in that the coating has at least partially penetrated into the second textile fabric. Thermal insulation material according to one or more of the preceding claims, characterized in that the second textile fabric lies at least partially outside the coating. Thermal insulation material according to one or more of the preceding claims, characterized in that the aerogel particles have a particle size distribution measured according to DIN 66165-2:2016-08 with a d50 value of 50 pm to 3 mm. Thermal insulation material according to one or more of the preceding claims, characterized in that the coating has a proportion of aerogel parti no of at least 60 wt.%, for example from 60 to 95 wt., based on the total weight of the coating, and / or the thermal insulation material has a proportion of aerogel parti no of 6 to 75 wt.%, based on the total weight of the thermal insulation material. Thermal insulation material according to one or more of the preceding claims, characterized in that the first and / or second textile sheet is a nonwoven fabric, which is preferably bonded with an at least partially water-soluble binder according to the method defined in the description.Thermal insulation material according to one or more of the preceding claims, characterized in that the first textile sheet is a nonwoven fabric, preferably a wet-laid nonwoven fabric, which is bound with a binder selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and blends thereof.Thermal insulation material according to one or more of the preceding claims, characterized in that the first and / or second textile fabric is a wet-laid nonwoven fabric, which is preferably bonded with an at least partially water-soluble binder according to the method defined in the description. Thermal insulation material according to one or more of the preceding claims, characterized in that the first and / or second textile fabric contains glass fibers, preferably with an average fiber length of 2 to 20 mm. Thermal insulation material according to one or more of the preceding claims, characterized in that the first and / or second textile fabric has a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm, preferably in the range from 0.3 mm to 2.5 mm, in particular in the range from 0.5 mm to 2.0 mm. Thermal insulation material according to one or more of the preceding claims, characterized in that the thermal insulation material has no water-insoluble binder or has a water-insoluble binder only in an amount of less than 10 wt.%, preferably less than 7.5 wt.%, in particular less than 5 wt.%, based on the total weight of the coating, wherein the water-insoluble binder is preferably a binder that is at least partially water-insoluble according to the method defined in the description.Electrochemical cell, preferably a lithium-ion cell, which is thermally insulated by at least one thermal insulation material according to one or more of the preceding claims and / or battery system in which at least one electrochemical cell, preferably at least one lithium-ion cell, is thermally insulated by at least one thermal insulation material according to one or more of the preceding claims. Cell module and / or battery system in which at least two electrochemical cells are thermally insulated from one another by at least one thermal insulation material according to one or more of the preceding claims. Method for producing a thermal insulation material for electrochemical cells, comprising the following steps: a) Providing a first textile sheet-like structure, preferably with a thickness, measured according to DIN EN ISO 9073-2:1997-02, in the range from 0.2 mm to 3.0 mm. b) Coating the textile fabric with a dispersion containing aerogel particles and a binder, wherein the binder b1) is at least partially water-soluble according to the method defined in the description, and / or wherein the binder b2) is preferably at least partially water-soluble according to the method defined in the description and wherein the binder is selected from the group consisting of polyvinyl acetate, preferably partially saponified polyvinyl acetate, polyvinyl alcohol, acrylate copolymer, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide, polyacrylamide, polyacrylic acid and salts thereof, polycarbonyl acid and salts thereof, polyamino acid, modified starch, ethoxylated starch, hydroxypropylated starch, modified cellulose, such as cellulose ethers, cellulose esters, cellulose amides and copolymers thereof, pullulan, guar gum, gum arabic, xanthan, carrageenan, cellulose, gelatin and salts thereof, dextrin, maltodextrin and copolymers and blends thereof;c) drying the resulting coating to form a heat-insulating layer. A process for recycling a heat-insulating material according to one or more of claims 1 to 16, comprising the following steps: a1) the heat-insulating material is comminuted and introduced into a solvent, preferably water; a2) it is stirred and optionally heated; a3) the aerogel particles and the fibers of the textile fabric are separated from one another. Use of a heat-insulating material according to one or more of claims 1 to 16 for heat management and / or thermal insulation of electrochemical cells, preferably lithium-ion cells, cell modules, and / or battery systems.

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