Conductive ceramic composite material and method for producing same

Abstract

The invention relates to a porous conductive ceramic composite material, to the use thereof, and to methods for producing same.

Description

[0001] Conductive ceramic composite material and methods for its production

[0002] The present invention relates to the technical field of conductive ceramics, in particular for catalytic or electrochemical applications.

[0003] In particular, the present invention relates to a thermally and / or electrically conductive porous ceramic composite material.

[0004] Furthermore, the present invention relates to shaped bodies containing or consisting of a conductive ceramic composite material.

[0005] Furthermore, the present invention relates to the use of a ceramic composite material for catalytic and / or electrochemical applications.

[0006] Furthermore, the present invention relates to compositions for the production of ceramic composite materials and methods for the production of ceramic composite materials.

[0007] Electrically conductive, mechanically resistant and cost-effective materials that can be manufactured on an industrial scale are becoming increasingly important in the context of the transition to renewable energies and the materials required for electrodes, batteries, etc.

[0008] Furthermore, porous electrically conductive materials are used as support materials for catalysts in chemical processes, especially in ohmic, i.e. resistively heated, reactors.

[0009] Electrically conductive materials are usually either of metallic origin or consist of a mixture, a so-called compound, of conductive particles incorporated into a binding matrix.

[0010] In addition, intrinsically conductive polymers, such as polyaniline, and intrinsically conductive ceramics, such as non-oxide ceramics, are known.

[0011] Metals are characterized by high electrical and thermal conductivity, which is caused by freely moving electrons. In addition to conductivity, metallic products exhibit high mechanical stability, enabling the production of very thin components with thicknesses of less than 50 pm. A significant disadvantage of using metals is their high weight, resulting from their high density, and especially their low corrosion resistance to acids and / or bases. Therefore, the materials must either be alloyed with additives or, for particularly high corrosion resistance—as is often required for electrochemical converters—coated with precious metals such as gold and platinum. However, the use of alloying elements negatively affects the material's conductivity, among other things. Coatings, in turn, carry the risk of either not being applied flawlessly or...Damage occurs due to aging. Defects of this kind usually lead to localized destruction of the material, which can result in the complete failure of the component.

[0012] Metal-containing electrodes are often used as binder-free electrodes, for example in the form of conventional pocket electrodes or sintered electrodes. While pocket electrodes consist of loose, compressed powder in perforated metal pockets, sintered electrodes are applied in powder form to a metallic matrix, the future current collector, and fused together at temperatures up to 950°C.

[0013] Besides purely metallic materials, conductive plastic compounds can also be used. These typically consist of a thermoset or thermoplastic, which serves as a binding, "adhesive" matrix for conductive fillers—usually carbon or metallic powders. Filler levels exceeding 70 wt% are necessary to achieve sufficient conductivity. While thermoset conductive compounds cannot be reshaped after curing, thermoplastic compounds can be remelted and subsequently reshaped.

[0014] In contrast to metals, polymeric compounds are characterized by a low density.

[0015] In addition, plastic-filler mixtures can be produced that are inert to a wide variety of chemicals. Although these materials offer the advantage of being processed using established manufacturing methods in the plastics industry, such as extrusion or injection molding, the high filler content significantly increases the material's viscosity, necessitating very high processing pressures of approximately 1,000 bar for extrusion or approximately 3,500 bar for injection molding. Furthermore, the poor flowability makes a minimum thickness of typically at least 3 mm essential for the molding compound. Moreover, the mixing of conductive particles in a non-conductive matrix prevents the material from achieving the conductivity of metals. Due to the matrix-forming plastic, these materials are also only suitable for use up to a maximum temperature of 250°C.

[0016] While in thermoset electrodes the filler particles are completely encased, made inaccessible to the electrolyte and thus immobilized, pressing with thermoplastics results in a significant reduction of porosity due to the applied pressure, which, as a consequence of poor wettability, means that not all of the active mass and any catalysts used are available for the conversion and storage of energy.

[0017] While polymer compound-based molding compounds are suitable for use as so-called bipolar plates for PEM fuel cells (polymer electrolyte membrane fuel cells), the inability to precisely control open porosity limits their use in many applications. For example, molding compounds for electrodes in energy storage applications must not only be electrically conductive and chemically inert, but also, and more importantly, exhibit an open-pore structure with specific pore sizes.

[0018] In addition to compounds, as previously mentioned, intrinsically conductive polymers are also known, which achieve their conductivity through conjugated double bonds that allow the free movement of electrons. However, these are not stable over the long term during oxidative or reductive processes. Furthermore, there is no way to selectively adjust the open porosity.

[0019] Besides plastics and metals, ceramics represent another class of technical materials.

[0020] Ceramics differ from plastics or metals in many properties and offer advantages for numerous applications, such as high hardness, wear resistance, and resistance to high temperatures. Intrinsically conductive ceramics exhibit an extremely wide range of electrical conductivity due to the diversity of chemical bonds found in ceramic materials. These bonds range from strong covalent bonds to ionic bonds and metallic bonding. Consequently, the effective conduction mechanisms vary from very good ionic conductivity to metallic electron conductivity.

[0021] Electrically conductive ceramics are predominantly produced using the sol-gel process according to current state of the art. The sol-gel process is a method for producing inorganic materials such as glass or ceramics. It is based on the conversion of liquid starting materials (sol) into a gel network, which is then transformed into a solid material by drying and heating. The production of thin films using the sol-gel process typically involves coating a surface with a thin layer of the liquid starting materials, the sol, which is then converted into a gel and finally transformed into a solid thin film by drying and heating (see Boumya, W., et al.; Modification strategies of sol-gel carbon ceramic electrodes and their electrochemical applications; Results in Chemistry, Volume 4; 2022; https: / / doi.Org / 10.1016 / j.rechem.2022.100623).

[0022] The coating process can be carried out using various techniques, such as dipping, spraying, or spin coating. Precise control of the layer thickness, temperature, and composition of the starting material allows for targeted manipulation of the thin film's structure and properties. The filler levels achieved in the sol-gel process can vary depending on the application and desired properties of the final product. However, filler levels exceeding 50 wt% are not achievable due to the agglomeration or clumping of fillers and the gel's viscosity, which increases with the filler level. Materials produced in this way are used as so-called ceramic composite electrodes (CCEs) for electrochemical analysis of gases, liquids, or solids and have numerous applications in environmental monitoring, biotechnology, and energy storage (see Bazli, L., et al.).; A review of carbon nanotube / TiO2 composite prepared via sol-gel method; Journal of Composites and Compounds, 1(1), 1-9; 2019; https: / / doi.Org / 10.29252 / jcc.1.1.1; and Burnat, B., et al.; Carbon black-modified carbon ceramic electrode - Its fabrication, characterization, and electroanalytical performance; Diamond and Related Materials, Volume 130; 2022; https: / / doi.Org / 10.1016 / j. diamond.2022.109513).

[0023] Furthermore, special ceramics are used as cathode material and as oxygen-ion-conducting electrolyte in so-called SOFCs (Solid Oxide Fuel Cells). In this cell type, the electrolyte consists of a solid ceramic material (classically yttrium-doped zirconium dioxide, YSZ) that is capable of conducting oxygen ions but is insulating to electrons. The cathode is also made of a ceramic material that is conductive to both ions and electrons.

[0024] In thermocatalysis, ceramic shapes, such as honeycomb structures, are used as support materials for catalytically active materials. The state of the art for preparing ceramic honeycombs for use as catalysts is coating. Since ceramic honeycomb monoliths exhibit low porosity due to sintering, the specific surface area available for the active component and reactions is limited. Therefore, the monoliths are often first coated with a porous layer, the so-called washcoat. The washcoat serves as a support layer for the active component, which is either impregnated onto the washcoat or already integrated within it. One advantage of coating is that the active component is applied only to the outer walls of the honeycomb, which saves a greater amount of catalyst material and thus reduces the costs associated with expensive precious metal catalysts.If the molded body to be coated already has sufficient porosity, it can also be directly impregnated with the active component.

[0025] For the catalytic reduction of NOx in so-called SCR processes, the catalytically active material, in the form of zeolites, is extruded as a monolith in a single manufacturing step. The production of zeolite-extruded monoliths typically involves mixing zeolite powder with a binder containing inorganic and organic components and water, followed by extrusion, drying, and finally calcination. Zeolite-extruded monoliths can be superior to zeolite-coated structures because they are less susceptible to abrasion. Carbon is typically used as a support in heterogeneous catalysis due to its high surface area and stability in acidic or basic media. Generally, carbon materials are applied to or extruded into monolithic structures to improve their adsorption capacity and reduce the pressure drop in the reaction.Although carbon-coated structures may exhibit better mechanical strength, extruded monoliths with good mechanical strength can also be produced.

[0026] Carbon-coated monoliths are typically used in environmental applications, such as selective catalytic reduction, hydrocarbon adsorption, and catalytic combustion systems. The common technique for coating monoliths with carbon is dip coating. This can be achieved by immersing a monolith in a liquid polymer followed by curing at the required temperature (see Govender, S.; Monoliths: A Review of the Basics, Preparation Methods and Their Relevance to Oxidation; Catalysts; Volume 7; 2017; https: / / doi.org / 10.3390 / catal7020062).

[0027] Carbon-extruded monoliths have attracted interest due to their potential as gas storage media. A carbon monolith can be produced by mixing a carbon precursor with a binder and a plasticizer, followed by extrusion, drying, and finally carbonization. It is possible to control the pore structure of the carbon during the monolith extrusion process. The extruded carbon monolith can thus exhibit a meso- and macroporous structure. This pore structure enables the reaction or adsorption of molecules with improved mass transfer and minimal pressure drop. To produce this structure, a porous silicon dioxide monolith is impregnated with a carbon polymer precursor and then carbonized. The silicon dioxide precursor can then be removed by acid treatment, leaving behind a negative carbon monolith.

[0028] Other templates or substrates for the fabrication of carbon monoliths include polymeric foams. In some cases, these stenciled structures can crack during fabrication. To solve this problem, a carbon source that acts as a self-bonding agent, such as sucrose or polyfurfuryl alcohol, can be used. The development of porous conductive structures is being widely promoted due to their diverse application possibilities.

[0029] JP 1112786 A describes the production of PVDF-based thin-film components modified by electrically conductive carbon blacks and electrically conductive ceramics. The ceramic does not serve as a bonding matrix and merely functions as an electrically conductive additive.

[0030] German patent DE 102004048098 A1 discloses the processing of highly concentrated and finely dispersed additive masterbatches in granular form, which exhibit improved dosing properties due to their incorporation into a wax. The granules are mixed into plastic compounds.

[0031] German patent DE 10 2007 043 447 A1 discloses a catalyst support with increased thermal conductivity, which is produced by incorporating a carbonizable chemical compound between layers of a layered silicate and subsequently carbonizing the incorporated chemical compound, leading to the formation of nanoscale graphites within the layered silicate layers. The thermal conductivity arises from the carbonization of the chemical compound, not from incorporated carbon.

[0032] EP 1 370497 A1 discloses a resistant and conductive coating produced using the sol-gel process. In this manufacturing process, the electrically conductive particles are encased by the ceramic mass in such a way that even at high filler levels, no conductive paths or contact points can form in the material.

[0033] EP 0 758 131 A1 describes a thermoplastic-based "Positive Temperature Coefficient Thermistor" (PTC thermistor) which exhibits electrical conductivity after the addition of a carbide powder. A thermoplastic is used as a binder for the ceramic materials.

[0034] WO 99 / 18031 A1 discloses a material made electrically conductive by the addition of carbon, which is shaped as a resistance heating element. The carbon-containing matrix is ​​obtained from water-soluble silicates, fluorosilicates, and silicate-containing fillers. However, the materials are not sintered; instead, the workpiece is treated at a maximum temperature of 250°C. A structure characteristic of ceramics is not formed in this process.

[0035] DE 10 2006 062 371 A1 describes an electrically conductive ceramic composite material suitable for various applications, particularly at high temperatures. The aim is to create a ceramic material whose electrical conductivity can be precisely controlled over a wide range and which exhibits improved thermal expansion behavior. The material consists of at least three ceramic components, with one base component being silicon nitride, SiA ION, or aluminum nitride. The electrical conductivity is influenced by at least two additional ceramic components, including an electrically conductive silicide of a metal and another ceramic component with lower electrical conductivity.

[0036] EP 4 171 796 B1 discloses a structured catalyst for catalyzing an endothermic reaction of a feed gas to convert it into a product gas, wherein the structured catalyst comprises at least one macroscopic structure made of an electrically conductive material and at least one connector attached to the at least one macroscopic structure, wherein the macroscopic structure carries a catalytically active material.

[0037] EP 3 801 900 A1 also discloses a structured catalyst with a macroscopic structure comprising an electrically conductive material and a ceramic coating. The macroscopic structure is produced by 3D printing or extrusion followed by sintering, whereby the macroscopic structure and the ceramic coating are sintered in an oxidizing atmosphere to form chemical bonds between the ceramic coating and the macroscopic structure. The ceramic coating carries catalytically active material for catalyzing the vapor-methane reforming reaction and is resistively heated.

[0038] The aforementioned methods and materials have in common that no easily manufactured porous and electrically conductive materials can be provided.

[0039] The state of the art therefore still lacks porous conductive materials, especially those that are both electrically and thermally conductive, which can be easily and cost-effectively manufactured on an industrial scale and are suitable for a wide variety of applications.

[0040] One object of the present invention is therefore to avoid, or at least mitigate, the disadvantages associated with the prior art described above.

[0041] In particular, it is an object of the present invention to provide a material which is porous, yet mechanically resistant and electrically and thermally conductive.

[0042] Another object of the present invention is to provide a material that is suitable for electrochemical applications as well as for catalytic applications.

[0043] Another object of the present invention is to provide a simple and reproducible method for the production of porous conductive materials.

[0044] The problem set out above is solved according to a first aspect of the present invention by a ceramic composite material according to claim 1; further, advantageous embodiments of this aspect of the invention are the subject of the related dependent claims.

[0045] A further subject matter of the present invention according to a second aspect of the present invention is a shaped body according to claim 16; further, advantageous embodiments of this aspect of the invention are the subject matter of the related dependent claims.

[0046] A further subject matter of the present invention according to a third aspect of the present invention is a use according to claim 19; further, advantageous embodiments of this aspect of the invention are the subject matter of the corresponding dependent claim.

[0047] A further subject matter of the present invention according to a fourth aspect of the present invention is a use according to claim 21. Furthermore, according to a fifth aspect of the present invention, a composition according to claim 22 is subject matter of the present invention; further advantageous embodiments of this aspect of the invention are the subject matter of the dependent claims.

[0048] Furthermore, according to a sixth aspect of the present invention, the subject matter of the present invention is a solid composition according to claim 28.

[0049] Furthermore, according to a seventh aspect of the present invention, the subject matter of the present invention is a method for producing a ceramic composite material according to claim 29; further advantageous embodiments of this aspect of the invention are the subject matter of the related dependent claims.

[0050] Finally, another subject matter of the present invention, according to an eighth aspect of the present invention, is a method for producing a ceramic composite material according to claim 32.

[0051] It goes without saying that any special features, characteristics, designs and embodiments, as well as advantages or the like, which are subsequently described in relation to only one aspect of the invention – for the purpose of avoiding unnecessary repetition – shall of course apply accordingly to the other aspects of the invention, without the need for any express mention.

[0052] Furthermore, it should be noted that for all relative or percentage quantities mentioned below, especially those based on weight, it must be ensured that, within the scope of the present invention, these quantities are selected by a person skilled in the art in such a way that the sum of the ingredients, additives, excipients, or the like always results in 100% or 100% by weight. This is self-evident to a person skilled in the art.

[0053] Furthermore, it should be noted that all parameter specifications mentioned below, or similar information, can in principle be determined or ascertained using standardized or explicitly specified determination methods, or using determination procedures that are generally familiar to the person skilled in the art.

[0054] Having stated this in advance, the subject matter of the present invention will be explained in more detail below. The subject matter of the present invention – according to a first aspect of the present invention – is a thermally and / or electrically conductive porous ceramic composite material, wherein the ceramic composite material comprises electrically conductive particles in amounts of at least 10 wt.%, based on the ceramic composite material.

[0055] Preferably, the ceramic composite material is at least electrically conductive, but preferably thermally and electrically conductive.

[0056] The present invention describes highly filled, electrically and thermally conductive ceramics, which enable the production of temperature-resistant, mechanically stable, definedly conductive, chemically resistant, and definedly open-pored workpieces. The ceramic composite materials according to the invention typically do not have an intrinsically electrically conductive ceramic material as a framework material or matrix, but rather obtain their electrical conductivity through electrically conductive fillers; they are therefore also referred to as electrically conductive ceramic composite materials.

[0057] Ceramic materials have the advantage that they are fundamentally easy to manufacture in almost any shape, are mechanically resilient, and their porosity can be specifically adjusted.

[0058] The porous ceramic composite material according to the invention acquires electrical and preferably also thermal conductivity through the presence of electrically conductive particles, making it suitable for a variety of electrical and electrochemical applications, such as electrodes or in battery technology, but also for shielding high-frequency radiation. Furthermore, the material is also ideally suited for catalytic purposes. The catalyst can be incorporated into the ceramic matrix during the production of the ceramic composite material or applied subsequently, for example by impregnation or electrochemical deposition.

[0059] In the context of the present invention, a ceramic material is understood to be a material containing a technical ceramic, i.e., a ceramic material. In addition to the actual technical ceramic, which forms the framework of the material, the ceramic material contains at least one filler, such as electrically conductive particles or particles of catalyst materials.

[0060] Ceramic materials are typically inorganic, non-metallic, and polycrystalline. They are generally formed from a ceramic powder or its dispersion in a liquid medium and only acquire their typical material properties through thermal treatment, particularly sintering at high temperatures.

[0061] Ceramics are often divided into the following groups:

[0062] - Silicate ceramics, which refer to a variety of inorganic non-metallic materials that can be classified into the types earthenware, stoneware, stoneware, and porcelain,

[0063] - Oxide ceramics, which consist predominantly of ionic compounds, such as aluminum oxide (Al2O3), zirconium dioxide (ZrO2), titanium(IV) oxide (TiO2), kaolin, bentonite, and

[0064] - Non-oxide ceramics, which consist predominantly of covalent compounds and are characterized by intrinsic conductivity; they often consist of metal-like carbides, such as silicon carbide (SiC), zirconium carbide (ZrC).

[0065] Within the scope of the invention, the ceramic composite materials typically acquire their conductive properties by adding electrically and / or thermally conductive particles. The ceramic masses form a binding matrix into which the conductive particles are incorporated.

[0066] Furthermore, the addition of conductive particles to (intrinsically conductive) non-oxide ceramics can significantly reduce their (weight and volume) fraction, as the conductive particles facilitate the conduction of electricity. This results in materials characterized by high electrical conductivity and high mechanical stability, whose open porosity can be adjusted to suit specific applications, including with the aid of volatile fillers. Moreover, the ceramic binders exhibit high chemical resistance. Ceramic composite materials according to the invention possess a multitude of advantages: For example, compared to polymer-based, electrically conductive compounds, a tenfold higher conductivity can be measured at the same volumetric fill level of conductive particles.

[0067] The open-pore structure increases the material's active surface area, which is particularly desirable as an electrode material for battery applications and electrolysis cells. Besides the possibility of producing defined open-pore structures, a further advantage compared to metals and especially plastics is the high temperature resistance and the associated dimensional stability.

[0068] The present invention enables the production of thermally highly resistant, thermally and electrically conductive, and mechanically stable molded bodies, which can be manufactured using common, established manufacturing processes from the plastics industry, such as extrusion, CIM, rolling mills, or additive manufacturing, in particular fused layer deposition. Fill levels can be achieved that are not attainable with current technology.

[0069] Furthermore, ceramic composite materials can be produced in all thicknesses. A significant advantage of the material is that the open porosity can be precisely controlled by adjusting the size of the filler particles, but especially by choosing the ceramic material, the water content of the slip, or by compacting purely powdered ceramic masses. Fillers and / or inorganic / organic pore-forming agents, which evaporate during the final thermal treatment, particularly firing (e.g., cellulose, ammonium carbonate), can also be used to create an open pore structure. Additionally, the choice of ceramic material determines the chemical resistance.

[0070] Within the scope of the present invention, the terms "porosity" and "pores" are understood to mean the cavity system within a continuous solid as well as on the outer surface of a continuous solid. Within the scope of the present invention, the open pores that are in contact with the environment and influence the surface properties of the ceramic composite material are particularly relevant.

[0071] Pores in solids are usually classified according to their pore size as follows:

[0072] Micropores with a pore size of less than 2 nm,

[0073] Mesopores with a pore size in the range of 2 to 50 nm, and

[0074] Macropores with a pore size greater than 50 nm.

[0075] In the context of the present invention, electrically conductive means a compound or material which has an electrical conductivity of at least 1 × 10⁻⁶ at 20 °C.-4 S • m -1 exhibits.

[0076] Within the scope of the present invention, it is preferred if the electrically conductive ceramic composite material has an electrical conductivity of at least 1 • 10 at 20 °C. -1 S • rr 1 , in particular 1 S • no. 1 , preferably 10 S • rr 1 preferably 10 2 S • m -1 Particularly good results are obtained when the electrically conductive ceramic composite material has an electrical conductivity of at least 1 × 10⁻⁶ at 20 °C. 3 S • rr 1 , in particular 1 • 10 4 S • m - 1 , exhibits. In particular, especially with ceramic composite materials that exhibit the aforementioned conductivities, particularly high-performance electrodes can be obtained.

[0077] Particularly good results are obtained within the scope of the present invention if the electrically conductive ceramic composite material has an electrical conductivity in the range of 1 to 10 at 20 °C. 6 S* nr 1 , in particular 10 2 up to 10 6 S • nr 1 , preferably 10 3 up to 10 6 S • nr 1 , exhibits. Materials with such high electrical conductivities are preferably used for electrochemical applications, as electrode materials or for applications in battery storage systems.

[0078] According to a further preferred embodiment of the present invention, the electrically conductive ceramic composite material has an electrical conductivity of 1 • 10 at 20 °C. -1 up to 10 2 S • rr 1 , in particular 1 • 10 -1 up to 10 S • rr 1 , preferably 1 • 10 -1 up to 1 S • rr 1Composite materials with these electrical conductivities are preferably used for catalytic applications and are ideally suited for resistive heating.

[0079] Particularly good results are obtained when the ceramic composite material contains electrically conductive particles in quantities of at least 20 wt.%, in particular at least 30 wt.%, based on the ceramic composite material.

[0080] Likewise, it can be provided that the ceramic composite material contains the electrically conductive particles in amounts of 10 to 99 wt.%, in particular 20 to 99 wt.%, preferably 30 to 98 wt.%, based on the ceramic composite material.

[0081] Regarding the chemical nature of the electrically conductive particles, these can be selected from a wide variety of chemical compounds. However, it has proven advantageous to choose electrically conductive particles from the following groups: carbon-containing materials, such as graphite, (high-conductivity) carbon black, carbon nanotubes (CNTs), etc.; metal-organic frameworks (MOFs); covalent organic frameworks (COFs); core-shell structured mesoporous materials, especially core-shell nanoparticles (CSNs); metals; metal oxides; semimetals; nitrides; carbides; intrinsically conductive ceramics, especially non-oxide ceramics; MAX phases; MXenes; and mixtures thereof.

[0082] Particularly good results are obtained within the scope of the present invention when the electrically conductive particles are from the group consisting of carbon-containing materials, metals, metal oxides, semimetals, nitrides, carbides, intrinsically conductive ceramics, in particular non-oxide ceramics, and mixtures thereof, preferably carbon-containing materials, metals, semimetals, nitrides, carbides and mixtures thereof.

[0083] The electrically conductive particle is preferably made of carbon-containing materials.

[0084] If the electrically conductive particles contain or consist of metal particles, it has proven advantageous to select the metal from the group of nickel, titanium, platinum, ruthenium, iron, zinc, copper, aluminum and their mixtures, in particular nickel, iron, zinc, copper, aluminum and their mixtures.

[0085] If the electrically conductive particles are or contain metal oxides, it has proven advantageous to select the metal oxide from the group consisting of tin(IV) oxide, manganese oxide, silver oxide, antimony oxide, cobalt(II,III) oxide, copper(II) oxide, lanthanum oxide, cerium(IV) oxide, aluminum oxide, titanium oxide, zirconium oxide, niobium oxide, and mixtures thereof. It is particularly preferred if the metal oxide is selected from the group consisting of tin(IV) oxide, manganese oxide, silver oxide, antimony oxide, cobalt(II,III) oxide, copper(II) oxide, lanthanum oxide, and mixtures thereof.

[0086] If the electrically conductive particles contain or consist of nitrides and / or carbides, the nitrides and / or carbides are preferably selected from metal nitrides, semimetal nitrides, metal carbides, semimetal carbides and mixtures thereof.

[0087] If the electrically conductive particles contain or consist of nitrides and / or carbides, it has proven advantageous for the electrically conductive particles to be selected from nitrides and carbides of elements in the group consisting of B, Al, Ti, Ga, In, Ti, Si, Ge, Sn, Pb, P, As, S, Cd, V, Cr, Mn, W, Co, Ni, Zn, Zr and their mixtures, preferably from nitrides and carbides of titanium and carbides of silicon, tantalum, tungsten and their mixtures. Preferably, the nitrides and carbides are selected from the group consisting of TiN, TiC, SiC, TaC, WC and their mixtures, in particular TiN, TiC, SiC and their mixtures.

[0088] As previously stated, electrically conductive particles are preferably carbon-containing materials. These carbon-containing materials are, in particular, particles selected from the group consisting of (conductive) carbon black, graphite, carbogels, graphene, carbon fibers, carbon nanotubes, onion-like carbons, and mixtures thereof. According to a particularly preferred embodiment of the present invention, the carbon-containing materials are carbon-based particles and are preferably selected from the group consisting of (conductive) carbon black, graphite, carbon fibers, and mixtures thereof, in particular (conductive) carbon black, graphite, and mixtures thereof. Within the scope of the present invention, a carbogel is understood to be a carbon-containing material obtained by gel synthesis, wherein the gel is carbonized and optionally activated. Within the scope of this invention, carbogels are, in particular, carbon aerogels, carbon xerogels, and carbon cryogels.Carbogels are porous particles whose specific pore volume of the mesopores, i.e., the pores with a size of 2 to 50 nm, determined by nitrogen adsorption and evaluation according to Barrett-Joyner-Halenda and / or t-plot method, is at least 0.5 cm. 3 / g, preferably at least 1.0 cm 3 / g, is the amount.

[0089] It is particularly preferred if the filler, in particular the electrically conductive filler, is selected from the group consisting of carbon, graphite, graphene, (conductive) carbon black, carbogels, carbon fibers, carbon nanotubes, silicon, silicon carbide, titanium carbide, tungsten carbide, tantalum carbide, titanium nitride, metals, metal fibers, metal compounds and mixtures thereof, in particular graphite, graphene, (conductive) carbon black, carbon fibers, carbon nanotubes, nickel, titanium, platinum, ruthenium, iron, zinc, copper, aluminum, silicon, silicon carbide, titanium carbide, tungsten carbide, tantalum carbide, titanium nitride and mixtures thereof, preferably graphite, graphene, (conductive) carbon black, carbon fibers, carbon nanotubes, nickel, iron, zinc, copper, aluminum, silicon, silicon carbide, titanium carbide, titanium nitride and mixtures thereof, graphite, (conductive) carbon black and mixtures thereof.

[0090] As for the particle size of the electrically conductive particles, this can also vary widely.

[0091] Typically, the electrically conductive particles have absolute particle sizes in the range of 0.02 to 2,000 pm, in particular 0.03 to 1,500 pm, preferably 0.04 to 1,000 pm.

[0092] However, it has also proven advantageous if the electrically conductive particles have a particle size distribution D90 in the range of 0.03 to 800 pm, in particular 0.04 to 700 pm, preferably 0.05 to 500 pm. Within the scope of this invention, the particle size distributions are determined, in particular, by means of static laser scattering (SLS). According to a preferred embodiment of the present invention, the electrically conductive particles are provided to have a multimodal, in particular biomodal, particle size distribution.

[0093] A multimodal, and especially a bimodal, particle size distribution ensures the highest possible fill level of the ceramic composite material with electrically conductive particles. By using particles with a multimodal or, in particular, a bimodal particle size distribution, it can be ensured that the smaller particles are embedded in the spaces between the larger particles, i.e., in the gaps of the sphere packing, thus reducing the distances between the individual particles and increasing contact between them. This increases the electrical conductivity of the ceramic composite material. Furthermore, different electrically conductive particles with different particle sizes can be used.

[0094] If the electrically conductive particles have a biomodal particle size distribution, it is preferred that the bimodal particle size distribution has a first maximum in the range of 1 to 300 pm, in particular 1 to 200 pm, preferably 1 to 150 pm, and a second maximum in the range of 0.01 to 50 pm, in particular 0.02 to 20 pm, preferably 0.05 to 10 pm.

[0095] In the context of the present invention, it is typically provided that the ceramic composite material comprises an inorganic framework material (matrix material). This material is the actual ceramic in which the electrically conductive particles are embedded. The inorganic framework material is thus the continuous phase in which fillers, such as electrically conductive particles, are dispersed.

[0096] In general, the inorganic framework material is selected from silicate ceramics, oxide ceramics, and non-oxide ceramics, as well as mixtures thereof. Preferably, the ceramic material is selected from the group consisting of silicate ceramics, oxide ceramics, and mixtures thereof. Most preferably, the ceramic material is an oxide ceramic.

[0097] In general, the inorganic framework material is selected from the group consisting of oxides, carbides, nitrides and their mixtures. In this context, it has proven particularly effective when the inorganic framework material is selected from the group consisting of aluminum oxide, silicon oxide, titanium dioxide, clay minerals, boron nitride, boron carbide, silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, zirconium oxide and their mixtures.

[0098] Within the scope of the present invention, it is particularly preferred if the inorganic framework material is selected from aluminium oxide, bentonite, kaolin and mixtures thereof.

[0099] Regarding the amounts of inorganic framework material contained in the ceramic composite, these can vary widely depending on the specific application. However, it has proven effective for the ceramic composite to contain at least 1% by weight, and in particular at least 2% by weight, of the inorganic framework material, based on the ceramic composite material.

[0100] Furthermore, it is preferred that the ceramic composite material contains the inorganic framework material in amounts of 1 to 80 wt.%, in particular 1 to 70 wt.%, preferably 2 to 60 wt.%, and more preferably 2 to 50 wt.%, based on the ceramic composite material. With a proportion of framework material in the prescribed amounts, highly filled, porous, yet mechanically resistant ceramic composite materials can be obtained.

[0101] According to a preferred embodiment of the present invention, the ceramic composite material comprises a catalyst or a catalyst-containing material.

[0102] A catalyst-containing material is understood to be, in particular, a support material which has at least one catalyst.

[0103] The catalyst, or the catalyst-containing material, is usually in particle form, i.e., in powder form, and is added to the composition for the production of the ceramic material as a filler. The ceramic material can be enhanced with catalytic activity by adding catalytically active material, thus making electrically and thermally conductive, catalytically active solid catalyst bodies available, which can be used, among other things, in a resistively heated reactor. The catalyst material can be selected as desired, depending on the catalytic process, provided it is a heterogeneously catalyzed process.

[0104] The catalytically active materials can be added directly to the porous ceramics during mixture preparation or added to the porous and conductive substrate in a subsequent step, including via electrochemical, hydrothermal or thermal steps.

[0105] If the ceramic material contains a catalyst or a catalyst-containing material, it has proven advantageous if the ceramic composite material contains the catalyst or the catalyst-containing material in amounts of at most 70 wt.%, in particular at most 60 wt.%, preferably at most 50 wt.%, preferably at most 40 wt.%, and most preferably at most 30 wt.%, based on the ceramic composite material.

[0106] Likewise, it can be provided that the ceramic composite material contains the catalyst or the catalyst-containing material in amounts of at least 0.1 wt.%, in particular at least 0.5 wt.%, preferably at least 1 wt.%, based on the composite material.

[0107] Furthermore, it may be provided that the ceramic composite material contains the catalyst or the catalyst-containing material in amounts of 0.1 to 70 wt.%, in particular 0.1 to 60 wt.%, preferably 0.5 to 50 wt.%, preferably 0.5 to 40 wt.%, particularly preferably 1 to 30 wt.%, based on the ceramic composite material.

[0108] The catalysts used in the present invention are generally known catalysts for chemical processes. In particular, the catalyst is selected from catalysts for exothermic or endothermic reactions, preferably for endothermic reactions. The ceramic composite material according to the invention is particularly well suited for catalyzing endothermic reactions, since the material is porous and, due to its electrically conductive particles, can also be used as a resistance heater in a resistively heated reactor. However, exothermic reactions can also be catalyzed with the ceramic material according to the invention, since the conductive particles typically give the ceramic material excellent thermal conductivity, allowing it to dissipate the heat of reaction generated.

[0109] However, endothermic reactions are particularly preferred, such as the cracking of hydrocarbons, the electrolysis of water or CO2, the reaction of methane to synthesis gas or the reaction of ethanol to butadiene.

[0110] The ceramic composite material according to the invention is particularly suitable for heterogeneous, i.e., catalysis of reactions in liquid or gaseous phases.

[0111] Catalysts preferably used within the scope of the present invention are transition metal catalysts, metal oxides or mineral catalysts, such as saponin.

[0112] As previously stated, the ceramic composite material according to the invention is porous and therefore suitable for a variety of applications in electrochemical or chemical processes.

[0113] According to a preferred embodiment of the invention, the ceramic composite material is used for electrochemical applications, in particular as an electrode or as a material for battery storage.

[0114] In this case, the ceramic composite material contains the electrically conductive particles in amounts of at least 60 wt.%, in particular at least 70 wt.%, preferably at least 80 wt.%, preferably at least 90 wt.%, particularly preferably at least 95 wt.%, based on the composite material.

[0115] Similarly, according to this embodiment, it can be provided that the ceramic composite material contains the electrically conductive particles in amounts of 60 to 99 wt.%, in particular 70 to 99 wt.%, preferably 80 to 98 wt.%, preferably 90 to 98 wt.%, particularly preferably 95 to 98 wt.%, based on the ceramic composite material.

[0116] Furthermore, according to this embodiment, it is preferred if the ceramic composite material contains the inorganic framework material in amounts of at least 1 wt.%, in particular at least 2 wt.%, based on the ceramic composite material.

[0117] Furthermore, it is preferred if the ceramic composite material contains the inorganic framework material in amounts of 1 to 40 wt.%, in particular 1 to 30 wt.%, preferably 2 to 20 wt.%, preferably 2 to 10 wt.%, preferably 2 to 5 wt.%, based on the composite material.

[0118] If the ceramic composite material is intended for electrochemical applications, particularly as an electrode, the ceramic composite material preferably has

[0119] (a) electrically conductive particles, especially in amounts of 60 to 99% by weight, and

[0120] (b) at least one inorganic framework material, in particular in amounts of 1 to 40% by weight, based on the ceramic composite material,

[0121] on.

[0122] According to another preferred embodiment, the ceramic composite material is used for catalytic applications.

[0123] When the ceramic composite material is used for catalytic applications, it has proven advantageous if the ceramic composite material contains electrically conductive particles in amounts of at least 10 wt.%, in particular at least 15 wt.%, preferably at least 20 wt.%, preferably at least 25 wt.%, based on the ceramic composite material.

[0124] Similarly, it can be provided that the ceramic composite material contains the electrically conductive particles in amounts of 10 to 50 wt.%, in particular 15 to 45 wt.%, preferably 20 to 40 wt.%, preferably 25 to 40 wt.%, based on the ceramic composite material. According to this embodiment, it is preferably provided that the ceramic composite material contains the inorganic framework material in amounts of at least 10 wt.%, in particular at least 15 wt.%, preferably at least 20 wt.%, preferably at least 25 wt.%, based on the ceramic composite material.

[0125] Furthermore, it is preferred if the ceramic composite material contains the inorganic framework material in amounts of 10 to 80 wt.%, in particular 15 to 70 wt.%, preferably 20 to 60 wt.%, preferably 25 to 50 wt.%, based on the ceramic composite material.

[0126] Likewise, it can be provided that the ceramic composite material contains the catalyst or the catalyst-containing material in amounts of at least 0.1 wt.%, in particular at least 0.5 wt.%, preferably at least 1 wt.%, based on the composite material.

[0127] Furthermore, it may be provided that the ceramic composite material contains the catalyst or the catalyst-containing material in amounts of 0.1 to 70 wt.%, in particular 0.1 to 60 wt.%, preferably 0.5 to 50 wt.%, preferably 0.5 to 40 wt.%, particularly preferably 1 to 30 wt.%, based on the ceramic composite material.

[0128] If the ceramic composite material is intended for catalytic applications, in particular as a whole-body catalyst, the ceramic composite material preferably has

[0129] (a) electrically conductive particles, in particular in amounts of 10 to 50 wt.%, (b) at least one inorganic framework material, in particular in amounts of 15 to 70 wt.%, and

[0130] (c) at least one catalyst or catalyst-containing material, in particular in amounts of 0.1 to 70 wt.%, in each case based on the ceramic composite material,

[0131] on.

[0132] Typically, within the scope of the present invention, the ceramic composite material has a specific pore volume, determined by nitrogen adsorption and evaluation according to the Barrett-Joyner-Halenda and / or t-plot method, in the range of 0.01 to 1.5 cm³. 3 / g, especially 0.05 to 1 cm 3 / g, preferably 0.1 to 0.9 cm 3 / g, preferably 0.13 to 0.8 cm 3 / g, exhibits.

[0133] Furthermore, it is possible that the ceramic composite material has a specific total surface area, determined according to Brunauer-Emmett-Teller (BET), of at least 30 m². 2 / g, in particular at least 35 m 2 / g, preferably at least 40 m 2 / g, preferably at least 50 m 2 / g, particularly preferably at least 60 m 2 / g. In this context, it is also possible that the ceramic composite material has a specific total surface area, determined according to Brunauer-Emmett-Teller (BET), of at most 1,200 m². 2 / g, in particular at most 1,000 m 2 / g, preferably no more than 800 m 2 / g. Particularly good results are obtained when the ceramic composite material has a specific total surface area, determined according to Brunauer-Emmett-Teller (BET), of 30 to 150 m². 2 / g, in particular at most 35 to 120 m 2 / g, preferably 40 to 110 m 2 / g, exhibits.

[0134] The ceramic composite material according to the invention can be formed into any shape, in particular as shaped bodies of virtually any thickness. Typically, the ceramic composite material has thicknesses in the range of 0.005 to 10 mm. Within the scope of the present invention, it is therefore particularly possible to produce very thin layers, for example in the form of sheets or sheets, but also as coatings. Very thin ceramic composite materials are particularly suitable for electrochemical applications, preferably as electrodes.

[0135] According to a preferred embodiment of the present invention, the ceramic composite material has a thickness of less than 1 mm, in particular less than 0.5 mm, preferably less than 0.3 mm.

[0136] Particularly good results are obtained when the ceramic composite material has a thickness in the range of 0.1 to 1 mm, in particular 0.1 to 0.5 mm, preferably 0.1 to 0.3 mm.

[0137] Such thin structures of the ceramic composite material are particularly suitable for electrochemical applications, especially in supercapacitors, batteries, or as electrodes. Another advantage of ceramic materials is that the material allows for complete manipulation of its shape by forming or molding until drying or thermal treatment. By selecting a ceramic binder and, in particular, the filler, the fired ceramic compounds can be used at high operating temperatures of up to 1200°C. The choice of conductive components added to the ceramic, as well as the water / pore-forming content, determines the porosity of the ceramic compound.

[0138] Another significant advantage of ceramic materials is the possibility of laminating. This allows ceramic layer structures to be produced / pasted within a single manufacturing step (anode - separator / oxide-based ion-conducting membrane - cathode). This drastically reduces the subsequent assembly of the materials. Similar to a screen printing process, 3D structures can be created in this way.

[0139] By mixing the powdered ceramic base mixture with water and / or paraffin and / or surfactant dispersion, the viscosity of the ceramic compound can be adjusted for the respective manufacturing process. Processing pure powder masses by isostatic pressing or additive manufacturing is also possible. The resulting green compact can then be conditioned, in particular deformed or shaped, until drying or thermal treatment. Furthermore, the ceramic masses can be produced in all material thicknesses, for example, from 0.005 mm to 10 mm. A key advantage of the material is that the open porosity can be precisely controlled by the size of the filler particles, but especially by the choice of ceramic or the water content of the slurry, or by compacting purely powdered ceramic masses.To achieve an open pore structure, fillers and / or inorganic or organic pore-forming agents can be used, which evaporate during the final thermal treatment, especially firing, such as cellulose or ammonium carbonate. Additionally, the choice of ceramic determines the chemical resistance.

[0140] By selectively adjusting the open porosity, the material can also be used as a gas diffusion electrode and / or porous transport layer, e.g., in fuel cells or electrolyzers for electrochemical CCh reduction. Furthermore, the ceramic composite materials according to the invention are highly electrically conductive. Due to the inventive production of the highly filled ceramic masses, the filler particles are not isolated; the ceramic does not completely encapsulate the filler particles, allowing the conductive particles to contact each other and enabling high electrical conductivity. Thus, a thermoplastic-based, highly filled plate exhibits an electrical resistance at least 10 times higher than volumetrically uniformly filled ceramic-based materials according to the invention.

[0141] For thermocatalytic applications, the invention provides a material that can be flexibly used for different catalyst materials and, unlike in the prior art, can be produced by an extrusion step without further coating steps.

[0142] A further object of the present invention - according to a second aspect of the present invention - is a shaped body containing or comprising, preferably comprising, a previously described ceramic material.

[0143] According to a preferred embodiment of the present invention, the shaped body is an electrode or an electrode layer.

[0144] According to an alternative, but equally preferred embodiment, the shaped body is a solid body catalyst, in particular a honeycomb catalyst.

[0145] For further details concerning the shaped body according to the invention, reference can be made to the above statements concerning the ceramic composite material according to the invention, which apply accordingly to the shaped body according to the invention, in order to avoid unnecessary repetition.

[0146] A further object of the present invention – according to a third aspect of the present invention – is the use of a previously described ceramic composite material in electrochemical cells, supercapacitors, resistance heating elements or heat exchangers, for shielding high-frequency radiation or as a battery storage material. According to a preferred embodiment of the present invention, the ceramic composite material is used as an electrode, in particular in battery applications, PEM fuel cells, AEM fuel cells and / or electrolysis cells.

[0147] The electrolysis cells are preferably low-temperature electrolyzers or capillary electrolyzers.

[0148] For further details on this aspect of the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly to the use according to the invention, in order to avoid unnecessary repetition.

[0149] A further object of the present invention - according to a fourth aspect of the present invention - is the use of a previously described ceramic composite material as a catalytic shaped body, in particular as a conductive full catalyst shaped body in a resistively heated reactor.

[0150] Preferably, the ceramic composite material is used as a conductive honeycomb catalyst in a resistively heated reactor.

[0151] For further details on this aspect of the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly to the use according to the invention, in order to avoid unnecessary repetition.

[0152] A further object of the present invention – according to a fifth aspect of the present invention – is a composition, in particular a moldable mass, for producing a previously described ceramic composite material and / or a previously described molded body, wherein the composition comprises (a) electrically conductive particles

[0153] (b) at least one inorganic framework material or its precursors and (c) at least one plasticizing agent

[0154] features. Within the scope of the present invention, it is preferably provided that the plasticizing agent is selected from the group consisting of water, organic solvents, organic polymers, dispersing agents, waxes, surfactants, cellulose derivatives and mixtures thereof.

[0155] A special feature of the composition according to the invention is that it preferably manages without or with only small amounts of organic binders.

[0156] Furthermore, it is preferred when mixtures of plasticizers are used.

[0157] Particularly good results are obtained when the plasticizing agent is selected from the group of water, dispersants, waxes, surfactants and their mixtures.

[0158] The composition typically contains the plasticizing agent in amounts of 5 to 60 wt.%, in particular 10 to 60 wt.%, preferably 20 to 55 wt.%, preferably 30 to 50 wt.%, based on the composition.

[0159] The composition typically contains the plasticizing agent in amounts of at least 5 wt.%, in particular at least 10 wt.%, preferably at least 20 wt.%, preferably at least 30 wt.%, based on the composition.

[0160] It is also possible that the composition contains the plasticizing agent in amounts of at most 60 wt.%, in particular at most 60 wt.%, preferably at most 55 wt.%, preferably at most 50 wt.%, based on the composition.

[0161] It has proven advantageous if the composition contains the inorganic framework material or its precursors in amounts of at least 0.5 wt.%, in particular at least 1 wt.%, preferably at least 2 wt.%, based on the composition.

[0162] Furthermore, it is preferred if the composition contains the inorganic framework material or its precursors in amounts of 0.1 to 40 wt.%, in particular 1 to 35 wt.%, preferably 2 to 30 wt.%, preferably 2 to 25 wt.%, based on the composition.

[0163] Furthermore, it has proven advantageous if the composition contains the electrically conductive particles in amounts of at least 5 wt.%, in particular at least 10 wt.%, preferably at least 15 wt.%, preferably at least 20 wt.%, based on the composition.

[0164] Likewise, it can be provided that the composition contains the electrically conductive particles in amounts of 5 to 70 wt.%, in particular 10 to 65 wt.%, preferably 15 to 65 wt.%, preferably 20 to 60 wt.%, particularly preferably 25 to 60 wt.%, based on the composition.

[0165] Furthermore, it is possible that the composition contains at least one pore-forming agent.

[0166] If the composition contains a pore-forming agent, the pore-forming agent is usually selected from the group of fillers, blowing agents, propellants and mixtures thereof.

[0167] The amount of pore-forming agent in the composition can naturally vary widely. However, it has proven effective if the composition contains the pore-forming agent in amounts of 0.1 to 15 wt.%, in particular 0.5 to 10 wt.%, preferably 1 to 8 wt.%, based on the composition.

[0168] According to a preferred embodiment, the composition

[0169] (a) electrically conductive particles, in particular in amounts of 5 to 70 wt.%, (b) at least one inorganic framework material or its precursors, in particular in amounts of 0.1 to 40 wt.%,

[0170] (c) at least one plasticizing agent, in particular in amounts of 5 to 60% by weight, and

[0171] (d) at least one pore-forming agent, in particular in amounts of 0.1 to 15 wt.%, in each case based on the composition.

[0172] For further details on this aspect of the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly to the composition according to the invention, in order to avoid unnecessary repetition.

[0173] A further object of the present invention – according to a sixth aspect of the present invention – is a solid composition for producing a previously described ceramic composite material and / or a previously described molded body, wherein the composition

[0174] (a) electrically conductive particles and

[0175] (b) contains at least one inorganic framework material or its precursors.

[0176] It has proven advantageous if the solid composition contains the electrically conductive particles in amounts of 10 to 99 wt.%, in particular 20 to 99 wt.%, preferably 30 to 98 wt.%, preferably 40 to 95 wt.%, particularly preferably 50 to 95 wt.%, based on the solid composition.

[0177] Furthermore, it is usually provided that the solid composition contains the inorganic framework material in amounts of 1 to 80 wt.%, in particular 2 to 70 wt.%, preferably 5 to 60 wt.%, preferably 5 to 50 wt.%, based on the solid composition.

[0178] Within the scope of the present invention, it may further be provided that the solid composition includes at least one pore-forming agent.

[0179] If the solid composition contains a pore-forming agent, the pore-forming agent is usually selected from the group of fillers, blowing agents, propellants and mixtures thereof.

[0180] The amount of pore-forming agent in the solid composition can naturally vary widely. However, it has proven effective if the composition contains the pore-forming agent in amounts of 0.1 to 15 wt.%, in particular 0.5 to 10 wt.%, preferably 1 to 8 wt.%, based on the solid composition.

[0181] According to a preferred embodiment, the solid composition comprises (a) electrically conductive particles, in particular in amounts of 10 to 99 wt.%, (b) at least one inorganic framework material or its precursors, in particular in amounts of 1 to 80 wt.%, and

[0182] (c) optionally at least one pore-forming agent, in particular in amounts of 0.1 to 15% by weight, based on the solid composition,

[0183] on.

[0184] The solid composition according to the invention is preferably in the form of a powder mixture and can be processed, for example, by means of isostatic pressing.

[0185] For further details on this aspect of the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly to the composition according to the invention, in order to avoid unnecessary repetition.

[0186] A further object of the present invention – according to a seventh aspect of the present invention – is a method for producing a previously described ceramic composite material, in particular a previously described shaped body, wherein

[0187] (i) in a first process step a previously described composition is produced,

[0188] (ii) in a subsequent second process step, the composition obtained in the first process step is formed so that a body, in particular a green body, is obtained, and

[0189] (iii) the body is subsequently subjected to thermal treatment.

[0190] Furthermore, it may be provided that the body obtained in process step (iii) is impregnated in a subsequent process step. The impregnation is preferably followed by a further thermal treatment. Impregnation can be used, for example, to introduce catalysts into or onto the ceramic composite material. The pore structure of the ceramic composite material is not altered or is altered only minimally.

[0191] The production of a ceramic composite material therefore preferably comprises at least one mixing step, one shaping step and at least one thermal treatment step.

[0192] Within the scope of the present invention, it is particularly possible to produce a kneadable mass, a so-called slurry, based on dry premixed ceramic-filler mixtures by adding a plasticizing agent, such as a liquid medium like water, and liquefying agents, such as paraffin, dispersants, lubricants, surfactants, and other surfactants. Inverse mixing by adding powdered starting materials to liquid media is also possible. In this process, the ceramic forms an adhesive, binding matrix in which the fillers are homogeneously embedded. In addition to the "wet" processes, it is also possible to process the ceramic masses as a dry powder mixture, as described below.

[0193] Slurry-based materials can be homogeneously mixed and processed into freely scalable molded parts, so-called green bodies, using established processing methods in the plastics industry, such as extrusion, ceramic injection molding (CIM), powder-to-roll processes, isostatic pressing, and 3D printing, especially fused layer modeling. Furthermore, the mixing of powders is independent of influences such as viscosity or filler content, resulting in a significant process advantage. This allows for filler levels well over 70 wt.%, exceeding the current state of the art.

[0194] For the electrically conductive, fully catalytic honeycomb structure, care must be taken when adding the liquid media to ensure that the mixture does not exceed a certain moisture content. The malleable mass is then processed into, for example, cylindrical shapes (green bodies) by being added to an extruder.

[0195] The material allows for complete manipulation of its shape by forming or deforming until drying or thermal treatment. If the focus is on catalytic activity, thermal treatment is carried out at a maximum temperature equal to the catalyst's operating temperature to prevent deactivation of the catalytic activity.

[0196] According to a preferred embodiment, a drying step is provided between process step (ii) and process step (iii).

[0197] The dried body is then subsequently subjected to the thermal treatment step, in particular a sintering process, according to process step (iii) in order to obtain the ceramic composite material.

[0198] Within the scope of the present invention, it is preferred if the drying is carried out at temperatures in the range of 30 to 150 °C, in particular 40 to 120 °C, preferably 50 to 100 °C.

[0199] Within the scope of the present invention, it is further preferred if a structured shaped body, a plate, a layer or a web is obtained by shaping the composition.

[0200] The shaping or forming can be done using common methods in plastics processing, such as extrusion, injection molding, doctor blades or the like.

[0201] Within the scope of the present invention, it is particularly possible for the composition to be applied to a substrate in the form of a layer or coating. Subsequent thermal treatment can then directly yield resistant, multilayered materials.

[0202] During the thermal treatment in process step (iii) the body is treated, in particular sintered, at temperatures in the range of 300 to 1,500 °C, in particular 300 to 1,400 °C, preferably 320 to 1,300 °C, more preferably 320 to 1,200 °C, particularly preferably 320 to 1,100 °C, most preferably 330 to 800 °C.

[0203] Preferably, the ceramic-filler mixture is combined in powder form. This offers the advantage of processing the material on plastics processing machines, such as extrusion or injection molding. Purely dry premixing or premixing with liquid media allows for filler levels that cannot be achieved with other materials as a binding matrix. This enables the incorporation of different particle morphologies and sizes into the ceramic matrix. Dry mixing of the powders is independent of viscosity and the high filler content. Furthermore, it can be precisely adjusted by adding water or paraffin.

[0204] By adding plasticizing agents, such as water and / or paraffin, to the dry premixed ceramic powders, as well as functional fillers, for example iron as an electrode active material, a malleable mass is formed whose viscosity can be adjusted for the respective manufacturing process. Compared to plastics, the use of flow agents, some of which are carcinogenic, can be avoided.

[0205] The resulting green compact can be manipulated until it dries or equipped with specific geometries, such as channel structures. The green compacts do not need to be bound by or incorporated into a polymer.

[0206] After thermal treatment, also called sintering or firing at temperatures above 800 °C, which takes place under inert gas, the ceramic composite material exhibits high mechanical stability and an open-pore structure.

[0207] Through thermal treatment and any prior drying, water and other volatile compounds are driven out of the material under thermal treatment conditions. This leads to the formation of porosity and shrinkage of the molding compound. In purely powder-based workpieces, in particular, the crystallization of the ceramic masses causes shrinkage during thermal treatment. This results in closer and thus better contact between the conductive fillers, leading to a significant increase in electrical conductivity. Compared to polymer-based, electrically conductive compounds with the same volumetric fill level of conductive particles, a tenfold higher conductivity can be measured. The amount of water used in the slurry or the pressure applied when pressing powder mixtures correlates with the resulting porosity in the material; more water or more pressure, respectively, produces higher porosity.Lower pressure results in larger pores or a higher number of pores.

[0208] The open-pore structure increases the material's active surface area, which is particularly desirable as an electrode material for battery applications and electrolysis cells. Besides the possibility of producing defined open-pore structures, a further advantage compared to metals and especially plastics is the high temperature resistance and the associated dimensional stability.

[0209] For further details on this aspect of the invention, reference can be made to the above statements on the other aspects of the invention, which apply accordingly to the method according to the invention, in order to avoid unnecessary repetition.

[0210] A further object of the present invention – according to an eighth aspect of the present invention – is a method for producing a previously described ceramic composite material, in particular a previously described shaped body, wherein

[0211] (i) in a first process step a previously described solid composition is produced or made available,

[0212] (ii) in a subsequent second process step, the solid composition obtained in the first process step is shaped and sintered to obtain a body made of a ceramic material.

[0213] The second process step (ii) can be carried out in particular as a powder bed process commonly used in additive manufacturing, such as selective laser sintering (SLS), or also by means of isostatic pressing.

[0214] For further details regarding this aspect of the invention, reference may be made to the above explanations concerning the other aspects of the invention, which apply accordingly to the method according to the invention, in order to avoid unnecessary repetition. The subject matter of the present invention is illustrated below in a non-limiting manner with reference to the exemplary embodiments. Exemplary embodiments

[0215] I. Production of various electrode and catalyst materials

[0216] 1. Production of an electrode material

[0217] 18 grams of graphite and 2 grams of bentonite were mixed with 10 ml of water and 2 ml of paraffin to form a malleable mass. The resulting mass was weighted down with a 10 kg weight and dried for 48 hours at ambient temperature. The green compact was then sintered under inert gas (argon or nitrogen) at 1050°C for 6 hours. After sintering, the material exhibits high mechanical stability and hardness, as well as high open porosity.

[0218] The resulting resistances are in the > 1 mQ range. Compared to a volumetrically uniformly filled polymer-based material, the resistance is about 10 times lower than that of the polymeric compounds.

[0219] 2. Production of an electrode material

[0220] 18 grams of graphite and 2 grams of kaolin were mixed with 10 ml of water and 2 ml of paraffin to form a malleable mass. The resulting mass was weighted down with a 10 kg weight and dried in a drying oven at 80°C for 6 hours. The green compact was then sintered under inert gas (argon or nitrogen) at 1050°C for 6 hours. After sintering, the material exhibits high mechanical stability and hardness, as well as high open porosity.

[0221] The resulting resistances are in the > 1 mQ range, analogous to the bentonite-based material. Compared to a volumetrically uniformly filled polymer-based material, the resistance is about 10 times lower than that of the polymeric compounds.

[0222] 3. Production of an electrode material

[0223] 56 grams of carbonyl iron, 3 grams of graphite, and 2 grams of bentonite were mixed with 50 ml of water and 2 ml of paraffin to form a malleable mass. The resulting mass was weighted down with a 10 kg weight and dried for 48 hours at ambient temperature. The green compact was then sintered under inert gas (argon or nitrogen) at 1050°C for 6 hours. After sintering, the material exhibits high mechanical stability and hardness, as well as high open porosity.

[0224] The resulting resistances are in the > 1 mQ range. Compared to a volumetrically uniformly filled polymer-based material, the resistance is about 10 times lower than that of the polymeric compounds.

[0225] A sample prepared in this way was cycled against a nickel electrode in a wet chemical setup. Capacities of 350 mAh / g of active mass were achieved, whereas only 250 mAh / g of active mass is known from the literature.

[0226] 4. Production of a catalyst material

[0227] The dry substances, 20 wt% calcined saponin (catalytically active material), 35 wt% graphite (TIMREX SFG1150), and 45 wt% of a ceramic base mixture (33.33 wt% aluminum oxide, 60 wt% kaolin, 6.67 wt% bentonite + based on the weight of the ceramic components: 2 wt% methylcellulose, 1 wt% PVA), were mixed. While stirring with a hand mixer, 4 wt% Parafol (based on the weight of the ceramic components) and 7.5 wt% ethanol (based on the weight of the aforementioned components) were added. Then, 45 wt% deionized water and ethanol (based on the weight of the aforementioned components) were added until agglomerates had formed.

[0228] The machine shaping for honeycomb structures and pellets was carried out using a single screw extruder from the manufacturer Ematik (model KEP 20-20-SK).

[0229] The screw was set to a rotational speed of 25 rpm. The material was forced by the screw through the pressure piece and finally through the die. Depending on the consistency of the material, it exited the die at a pressure of 25 to 35 bar.

[0230] For drying, the green compacts were transferred to a drying oven. Initially, the molded parts remained in the oven at 35 °C for 7 hours. The temperature was then increased to 55 °C, 85 °C, and finally 105 °C, each temperature being held for 7 hours. After drying, the molded parts cooled at ambient temperature. For heat treatment, the dried molded parts were placed in heat-resistant calcining boats. The filled boats were placed in a tube furnace (ThermConcept, ROK 150 / 750 / 11 / -3z). This furnace was sealed and, during the heat treatment, a flow of 5.29 Nl / min of synthetic air was performed. The furnace was heated at 5 °C / min to a target temperature of 350 °C. The target temperature was held for 4 hours to ensure complete removal of the temporary binders and any remaining water.

[0231] II. Production and testing of electrode materials

[0232] The electrodes are made from an iron-containing paste consisting of varying amounts of powders such as iron, ceramic, graphite and soot, the properties of which are given in Table 1.

[0233] Table 1: Particulate starting materials used

[0234]

[0235] In addition to the powdered materials, a polyethylene glycol (PEG) solution was added to the powders, which has a positive effect on the viscosity and facilitates shaping.

[0236] The electrodes were manufactured by coating strips of nickel mesh with iron-containing pastes consisting of a fixed amount of iron powder (80 wt%), 10 wt% ceramic, 8 wt% C-Therm, 2 wt% carbon black, and PEG, followed by sintering. All powders were milled before the addition of the PEG solution to mix and grind the powders, which had different densities, using an IKA mill.

[0237] The strips of nickel mesh were coated by manually rolling the iron-containing paste onto the nickel mesh. The electrode manufacturing process was standardized and carried out in the following steps: 1. All nickel mesh strips had the same weight (1.0 g) and dimensions (7 cm x 2 cm x 0.35 mm).

[0238] 2. A constant amount of the active paste, 3.0 g, was applied to the nickel mesh. During this coating process, the iron-containing paste was rolled onto the nickel mesh in one direction, and the coated electrode was also weighed to ensure a comparable weight for all electrodes. The active mass of the iron electrodes was 1.55 g.

[0239] 3. The total mass of the iron electrodes was in the range of 2.5 to 3.5 g.

[0240] 4. The total thickness of the iron electrodes ranged from 0.6 to 1.0 mm with nickel mesh, i.e., from 0.25 to 0.65 mm for the coating (total thickness minus nickel mesh thickness).

[0241] Afterwards, the electrodes were first dried for at least 4 hours and then sintered in a tube furnace with a nitrogen atmosphere:

[0242] 1. Heating ramp (RMP; the rate of temperature change over time) to the target temperature, in °C per minute)

[0243] 2. Target temperature

[0244] 3. Dwell time

[0245] The respective test conditions are given in Table 2 below.

[0246] Table 2: Temperature program of the sintering process

[0247]

[0248] The charging and discharging tests were performed under galvanostatic conditions at room temperature until steady state was reached. The iron electrodes were cycled at various C-rates (0.12 C, 0.2 C, and 0.5 C) and a potential change of 0.8 to 1.6 V. The C-rate is a measure of the rate at which a battery is discharged relative to its maximum capacity. A NiFe cell has a theoretical specific capacity of approximately...

[0249] 293 mAh / g.

[0250] The measurements presented here were performed using a two-electrode setup in which the two electrodes are connected to the current-collecting nickel meshes by sheer mechanical force, through clamping the electrodes together. Such an approach may not allow for proper current transport and collection to the electrode, as the contact resistance is high or the electrolyte becomes trapped between the electrode and the nickel mesh. This leads to significant current losses, which impair the charge and discharge cycles of the tested electrodes and ultimately the reproducibility of the test results.

[0251] To overcome this problem, the FeGCCEs were pressed onto a bipolar plate, which had previously been applied to the nickel mesh, before being examined. This approach allows for higher current transport to the FeGCCEs under investigation, but also easier handling of the generated electrodes, since they are firmly bonded to the nickel mesh.

[0252] An additional advantage of this method, which brings the produced materials a step closer to their application goal, is that BPPs can be bound on both sides of the nickel mesh, which allows for easier stacking of the produced cells.

[0253] The resulting values ​​fluctuate between 252 and 261 mAh / g during the cycling experiment.

Claims

Patent claims:

1. Thermally and / or electrically conductive porous ceramic composite material, characterized by that the ceramic composite material contains electrically conductive particles in quantities of at least 10% by weight, based on the ceramic composite material.

2. Ceramic composite material according to claim 1, characterized in that the ceramic composite material comprises the electrically conductive particles in amounts of at least 20 wt.%, in particular at least 30 wt.%, based on the ceramic composite material.

3. Ceramic composite material according to claim 1 or 2, characterized in that the ceramic composite material comprises the electrically conductive particles in amounts of 10 to 99 wt.%, in particular 20 to 99 wt.%, preferably 30 to 98 wt.%, based on the ceramic composite material.

4. Ceramic composite material according to one of the preceding claims, characterized in that the electrically conductive particles are selected from the group consisting of carbon-containing materials, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), core-shell structured mesoporous materials, in particular core-shell nanoparticles (CSN), metals, metal oxides, semimetals, nitrides, carbides, non-oxide ceramics, MAX phases, MXenes and mixtures thereof.

5. Ceramic composite material according to one of the preceding claims, characterized in that the ceramic composite material comprises an inorganic framework material.

6. Ceramic composite material according to claim 5, characterized in that the inorganic framework material is selected from the group consisting of oxides, carbides, nitrides and mixtures thereof.

7. Ceramic composite material according to claim 5 or 6, characterized in that the inorganic framework material is selected from the group consisting of aluminum oxide, silicon oxide, titanium dioxide, clay minerals, boron nitride, boron carbide, silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, zirconium oxide and mixtures thereof.

8. Ceramic composite material according to one of claims 5 to 7, characterized in that the ceramic composite material comprises the inorganic framework material in amounts of at least 1 wt.%, in particular at least 2 wt.%, based on the ceramic composite material.

9. Ceramic composite material according to one of claims 5 to 8, characterized in that the ceramic composite material comprises the inorganic framework material in amounts of 1 to 80 wt.%, in particular 1 to 70 wt.%, preferably 2 to 60 wt.%, preferably 2 to 50 wt.%, based on the ceramic composite material.

10. Ceramic composite material according to one of the preceding claims, characterized in that the ceramic composite material comprises a catalyst or a catalyst-containing material.

11. Ceramic composite material according to claim 10, characterized in that the ceramic composite material comprises the catalyst or the catalyst-containing material in amounts of at most 70 wt.%, in particular at most 60 wt.%, preferably at most 50 wt.%, preferably at most 40 wt.%, particularly preferably at most 30 wt.%, based on the ceramic composite material.

12. Ceramic composite material according to claim 10 or 11, characterized in that the ceramic composite material comprises the catalyst or the catalyst-containing material in amounts of 0.1 to 70 wt.%, in particular 0.1 to 60 wt.%, preferably 0.5 to 50 wt.%, preferably 0.5 to 40 wt.%, particularly preferably 1 to 30 wt.%, based on the ceramic composite material.

13. Ceramic composite material according to one of claims 10 to 12, characterized in that the catalyst is selected from catalysts for exothermic reactions or for endothermic reactions, preferably for endothermic reactions.

14. Ceramic composite material according to one of the preceding claims, characterized in that the ceramic composite material has a specific pore volume, determined by nitrogen adsorption and evaluation according to the Barrett-Joyner-Halenda and / or t-plot method, in the range of 0.01 to 1.5 cm³ 3 / g, especially 0.05 to 1 cm3 / g, preferably 0.1 to 0.9 cm 3 / g, preferably 0.13 to 0.8 cm 3 / g, exhibits.

15. Ceramic composite material according to one of the preceding claims, characterized in that the ceramic material has a specific total surface area, determined according to Brunauer-Emmett-Teller (BET), of at least 30 m² 2 / g, in particular at least 35 m 2 / g, preferably at least 40 m 2 / g, exhibits.

16. Molded body, containing or comprising, preferably comprising, a ceramic composite material according to any one of claims 1 to 15.

17. Molded body according to claim 16, characterized in that the molded body is an electrode or an electrode layer.

18. Molded body according to claim 16, characterized in that the molded body is a honeycomb catalyst.

19. Use of a ceramic composite material according to any one of claims 1 to 15 as a conductive material in electrochemical cells, supercapacitors, resistance heating elements or heat exchangers, for shielding high-frequency radiation or as a battery storage material.

20. Use according to claim 19 as an electrode, in particular in battery applications, PEM fuel cells, AEM fuel cells and / or electrolysis cells.

21. Use of a ceramic material according to any one of claims 1 to 15 as a catalytic molded body, in particular as a conductive solid catalyst molded body in an ohmic reactor.

22. Composition, in particular a moldable mass, for producing a ceramic composite material according to any one of claims 1 to 15 and / or a molded body according to any one of claims 16 to 18, characterized in that the composition (a) electrically conductive particles (b) at least one inorganic framework material or its precursors and (c) at least one plasticizing agent exhibits.

23. Composition according to claim 22, characterized in that the plasticizing agent is selected from the group consisting of water, organic solvents, organic polymers, dispersants, waxes, surfactants, cellulose derivatives and mixtures thereof.

24. Composition according to claim 22 or 23, characterized in that the composition comprises the plasticizing agent in amounts of 5 to 60 wt.%, in particular 10 to 60 wt.%, preferably 20 to 55 wt.%, preferably 30 to 50 wt.%, based on the composition.

25. Composition according to one of claims 22 to 24, characterized in that the composition comprises at least one pore-forming agent.

26. Composition according to claim 25, characterized in that the pore-forming agent is selected from the group consisting of fillers, blowing agents, propellants and mixtures thereof.

27. Composition according to claim 25 or 26, characterized in that the composition comprises the pore-forming agent in amounts of 0.1 to 15 wt.%, in particular 0.5 to 10 wt.%, preferably 1 to 8 wt.%, based on the composition.

28. Solid composition for the production of a ceramic composite material according to one of claims 1 to 15 and / or a shaped body according to one of claims 16 to 18, characterized in that the composition (a) electrically conductive particles and (b) contains at least one inorganic framework material or its precursors.

29. Method for producing a ceramic composite material, in particular a shaped body, according to one of claims 1 to 15, characterized in that (i) in a first process step a composition according to one of claims 22 to 27 is produced, (ii) in a subsequent second process step, the composition obtained in the first process step is formed to obtain a body, and (iii) the body is subsequently subjected to thermal treatment.

30. Method according to claim 29, characterized in that a drying step is carried out between process step (ii) and process step (iii).

31. Method according to claim 29 or 30, characterized in that the body is a structured shaped body, a plate, a layer or a web.

32. Method for producing a ceramic composite material, in particular a shaped body, according to one of claims 1 to 15, characterized in that (i) in a first process step a solid composition according to claim 28 is produced, (ii) in a subsequent second process step, the solid composition obtained in the first process step is shaped and subjected to thermal treatment to obtain a ceramic body.

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