Improving the mechanical properties of electrocatalytically active composites

Abstract

The invention is concerned with electrocatalytically active or activatable laminates, and the production and use thereof as anion exchange membrane (AEM) in alkaline water electrolysis. One object of the invention was that of providing a laminate with minimum swelling when used as AEM in alkaline water electrolysis. This is achieved with a textile fabric which is used as reinforcement. An essential aspect of the invention is that of coordination of the fibre material with the membrane material: A fibre material having chemical similarity to the membrane material is used. The chemical similarity mentioned consists in the repeat units of the polymeric fibre material and the ionomer, each of which has at least two phenylene groups.

Description

[0001] 202400195 Foreign Filing 1

[0002] Improving the mechanical properties of electrocatalytically active composites

[0003] Field of the invention

[0004] The invention is concerned with electrocatalytically active or activatable laminates, and the production and use thereof as anion exchange membrane in alkaline water electrolysis.

[0005] Technical background

[0006] Catalyst coated membranes (CCMs) are laminates comprising at least one first layer comprising an ionconducting polymer (ionomer) and at least one second layer comprising an electrocatalytically active or activatable material (electrocatalyst). The first layer acts as a membrane and the second layer acts as a catalyst. There is direct contact between the ionomer layer and the electrocatalyst layer via a boundary layer. The boundary layer is ideally infinitesimally thin; in reality, the catalyst layer and the ionomer layer merge into one another and collectively form the boundary layer in their transition region.

[0007] CCMs are installed in electrochemical cells, such as in fuel cells or in electrolysers. The chemical nature of the electrocatalyst and the ionomer depends on the intended application of the electrochemical cell. One application is water electrolysis for production of hydrogen and oxygen (water splitting).

[0008] One variant of water splitting is alkaline membrane water electrolysis. It is important that the membranes have a good conductivity for hydroxide anions (OH ). This conductivity is realized by anion-conducting polymers. The membranes produced from these ionomers are therefore referred to as anion exchange membranes (AEM). Since the reaction is carried out in an alkaline environment the AEM must be stable under alkaline conditions. Alkaline membrane water electrolysis is often also referred to as AEM-based water splitting (AEM water electrolysis - AEMWE).

[0009] An excellent overview of the current state of development of AEM-based water splitting is given by:

[0010] Volk Emily K. et al.: Recent progress in understanding the catalyst layer in anion exchange membrane electrolyzers - durability, utilization, and integration. EES. Catal., 2024,2, 109-137 DOI 10.1039 / d3ey00193h

[0011] A major technical problem when CCMs are used in AEMWE is the swelling: In the alkaline environment of the cell, the ionomer absorbs the water present in the aqueous electrolyte and swells as a result. This causes a geometric change in dimensions of the CCM, which is generally anisotropic. This deforms the whole cell, resulting in unwanted leaks or unwanted electrical contacts. Moreover, the swelling regularly causes detachment of the catalyst layer from the membrane. In addition, the swollen CCM is more susceptible to external forces. 202400195 Foreign Filing 2

[0012] The swelling of the membrane is a problem not only during electrolysis operation but also in the course of manufacture of the CCM: To wit, the catalyst layer is generally applied to the ionomer layer in the form of a solvent-containing catalyst ink. After the solvent has dried, the catalyst ink solidifies and forms the catalyst layer on the ionomer layer. If the ionomer swells in the solvent, this leads to distortion of the ionomer layer in the coating operation, causing the coated membrane to wrinkle. It is barely possible to install a wrinkled membrane in an electrochemical cell without leaks.

[0013] It is not only the wrinkles caused by the swelling of the membrane that make it difficult to install the membrane in the electrolyser. Even if the membrane is as wrinkle-free as possible, unevenness in its surface can have an adverse effect on its contactability: In an electrolysis cell, the membrane is generally installed in what is called a stack composed of the membrane including the catalyst layer, gas-permeable transport layers (gas diffusion layers - GDL) and the electrodes. If the surface of the catalyst layer is very uneven, this causes local mechanical stress peaks in the stack at the contact with the transport layer. These voltage peaks can mechanically damage the catalyst layer. It is therefore in the interests of the service life of the catalyst layer for its surface to be of maximum flatness.

[0014] Prior art

[0015] In order to counter the problem of swelling in the production of AEM CCMs, Susanne Koch's research group developed a process for catalytic coating of AEM in which the membrane is protected against distortion in the course of coating by means of masking:

[0016] Koch, S., Metzler, L., Kilian, S. K., Heizmann, P. A., Lombeck, F., Breitwieser, M., Vierrath, S., Toward Scalable Production: Catalyst-Coated Membranes (CCMs) for Anion-Exchange Membrane Water Electrolysis via Direct Bar Coating. Adv. Sustainable Syst. 2023, 7, 2200332. DOI: 10.1002 / adsu.202200332

[0017] A flat, anion-conducting membrane is first masked here with a PTFE film and directly coated in its free areas with a catalyst ink. A protective film likewise made of PTFE is additionally attached by adhesive bonding. The mask is used to absorb stresses in the membrane to ensure that the membrane does not warp excessively during coating.

[0018] The disadvantage of the process proposed by Koch et al. is that it requires the masking film to prevent swelling of the membrane and thus ultimately wrinkle formation. The mask serves exclusively for production of the CCM and must be removed from the CCM again in the ready-to-use state. Since the mask is made of the fluoropolymer PTFE, throwing it away is objectionable for environmental reasons. The process also requires a lot of manual work and does not yet appear to be scalable from an industrial standpoint. In addition, the catalyst ink used by Koch et al. contains methanol as solvent. Since methanol is known to be carcinogenic, mutagenic or toxic to reproduction, this solvent is classified as a CMR substance according to the REACH regulation and thus requires appropriate safety measures when used. 202400195 Foreign Filing 3

[0019] This does not cause any great difficulties in the laboratory, but on an industrial production scale this is very complex and correspondingly costly.

[0020] Another way of reducing the swelling of the membrane is to incorporate a reinforcement into the laminate. The reinforcement is usually a foil or a textile fabric:

[0021] For instance, EP 2774203 B1 discloses a method of producing a reinforced CCM which is used as a proton exchange membrane (PEM). Accordingly, the ionomer used in that case has no conductivity for hydroxide ions and therefore cannot be used in the AEMWE. The reinforcement is a porous film.

[0022] WO 2024100383 A2 describes a catalytically active membrane that can be anion-conducting. The production thereof involves applying the membrane layer to the previously produced catalyst layer. This laminate is thus not a catalytically coated membrane in the strict sense of the word, but a catalyst layer with ion-conducting coating. For the purpose of strengthening, this laminate is reinforced. The structure of the reinforcement is not disclosed in detail.

[0023] WO 2024100413 A1 discloses a PEM-CCM provided with a Pt / C electrocatalyst. The CCM includes a strengthening means composed of a nonwoven to improve its mechanical properties.

[0024] WO2024151961A1 describes a process for producing a reinforced AEM with an aromatic polymer. The application does not include any examples.

[0025] Malikah Najibah et al. have developed an anion exchange membrane for use in water electrolysis, reinforced with a scrim composed of PBI fibres:

[0026] Malikah Najibah, Ekaterina Tsoy, Hamza Khalid, Yongfang Chen, Qingfeng Li, Chulsung Bae, Jaromir Hnat, Michaela Plevova, Karel Bouzek, Jong Hyun Jang, Hyun S. Park, Dirk Henkensmeier: PBI nanofiber mat-reinforced anion exchange membranes with covalently linked interfaces for use in water electrolysers. Journal of Membrane Science, Volume 640, 2021 , 119832. DOI 10.1016 / j.memsci.2021.119832

[0027] Various strategies for strengthening of CCMs used in the AEMWE are presented by:

[0028] Henkensmeier, Dirk et al.: Separators and Membranes for Advanced Alkaline Water Electrolysis. Chemical Reviews, Vol. 124, Is 10, 6393-6443. DOI 10.1021 / acs.chemrev.3c00694

[0029] This article also describes established test methods for membranes used in the AEMWE and gives standard performance values. 202400195 Foreign Filing 4

[0030] This applicant's EP 24169671 .5, which was yet to be published at the time of this application, relates to a process for producing an unreinforced catalytically active membrane for the AEMWE in which the ionomer layer is applied to the catalyst layer.

[0031] With regard to this prior art, it was an object of the invention to provide an electrocatalytically active or activatable laminate of maximum stability against external forces when used as AEM in alkaline water electrolysis, especially in the moist state. The laminate should be produced with a minimum level of wrinkles and show good performance when used as intended. Moreover, the laminate should be produced through a rapid process that does not compromise its properties, for instance, by avoiding / minimizing the entrapment of air bubbles. The catalyst layer should have good adhesion to the membrane and not peel off. The catalyst layer should have a surface of maximum flatness. Finally, the production process should as far as possible avoid substances of concern in respect of health or the environment. In particular, no CMR substances or fluoropolymers should be used.

[0032] Achievement

[0033] This object is achieved by a process for producing an electrocatalytically active or activatable laminate, comprising the following non-chronological steps: a) providing a transfer substrate; b) providing a catalyst ink comprising at least one first solvent, at least one polymeric binder dissolved in the first solvent, and at least one particulate electrocatalyst; c) applying the catalyst ink to the transfer substrate to form a fresh catalyst layer on the transfer substrate; d) depleting the first solvent from the fresh catalyst layer so as to form, on the transfer substrate, a solid catalyst layer comprising at least two phases, namely a first phase which is formed by the now undissolved polymeric binder and a second phase which is formed by the particulate electrocatalyst, where the second phase is dispersed in the first phase; e) optionally: separating the transfer substrate from the solid catalyst layer; f) providing an ionomer solution comprising at least one second solvent and at least one anion-conducting polymer dissolved in the second solvent, where the first and second solvents are identical or different; g) providing a textile fabric comprising fibres of a polymeric fibre material; 202400195 Foreign Filing 5 h) impregnating the textile fabric with the ionomer solution in the presence of the solid catalyst layer so as to form, on the solid catalyst layer, a fresh ionomer layer comprising the textile fabric impregnated with the ionomer solution; i) depleting the second solvent from the fresh ionomer layer so as to form, on the solid catalyst layer, a solid ionomer layer comprising the textile fabric and the now undissolved anion-conducting polymer, where the textile fabric is completely or partly embedded in a matrix formed by the anion-conducting polymer; k) if not yet done: separating the transfer substrate from the solid catalyst layer; l) obtaining the electrocatalytically active or activatable laminate, where the laminate comprises the solid catalyst layer and the solid ionomer layer applied thereto; in which the textile fabric and the ionomer solution are provided with the proviso that the polymeric fibrous material has a first repeat unit comprising at least two phenylene groups, and the anion-conducting polymer has a second repeat unit comprising at least two phenylene groups, where the first and second repeat units are identical or different.

[0034] The invention firstly provides a process of this kind.

[0035] The production process of the invention leads to an electrocatalytically active or activatable anion- conducting laminate with a textile reinforcement. The laminate is thus a fibre composite having a matrix of the ionomer and fibres of the fibre material embedded therein. An essential aspect of the invention is that of coordination of the fibre material with the membrane material: According to the invention, a textile fabric is used as reinforcement, the fibre material of which has a certain chemical similarity to the membrane material (ionomer). Given this chemical similarity, particularly good adhesion of the ionomer to the fibre is observed, and so reliable transmission of force from the membrane to the fibre is assured. The good adhesive bond means that the internal forces that act through swelling in the membrane layer are transferred to the textile fabric and are absorbed therein under low strain. This results in a smaller change in dimensions of the overall laminate in spite of swelling stress from the ionomer. The strengthening also counteracts forces acting on the laminate from the outside, which are likewise absorbed by the fibres. Strain under external forces is likewise reduced. The low strain on the membrane also benefits adhesion of the catalyst layer thereto: Flaking of the catalyst under external load is distinctly reduced.

[0036] According to the invention, the aforementioned chemical similarity is in the repeat units of the polymeric fibre material and the ionomer, each of which have at least two phenylene groups. To wit, the invention is based on the finding that adhesion between ionomer and fibre material is improved when the two polymers each have two phenylene groups. Also inherent to the invention is the finding that there is a class of anion-conducting polymers that are characterized by two phenylene groups, and also a class of 202400195 Foreign Filing 6 fibre polymers that likewise have two phenylene groups. The teaching of the invention thus consists in selecting the fibre polymer and the ionomer with the proviso that the two substances each have two phenylene groups.

[0037] It is assumed that there is a chemical interaction between the phenylene groups of the fibre polymer and the ionic conductive polymer, which ultimately results in particularly stable adhesion between the ionomer matrix and the textile fabric embedded therein.

[0038] The binding forces achieved in this way are sufficiently strong that complete embedding of the textile fabric in the matrix is not even necessary: partial embedding is sufficient. Partial embedding can be at discrete points or else off-centre, such that the textile structure remains discernible at least on one side. However, the embedding must not be so slight that the intrinsic porosity of the textile fabric in the laminate is maintained. The final laminate must be gas-tight in order to prevent mixing the gases hydrogen H2 and oxygen O2 that arise in water electrolysis, because the latter increases the risk of a hydrogen-oxygen gas explosion. For that reason, it is necessary to observe a degree of embedding that assures gas impermeability of the laminate. Mere coating of the fibres, where the gas-permeable pores of the textile fabric are maintained, thus does not constitute embedding for the purposes of the invention.

[0039] An essential feature of the present process is that the textile fabric is impregnated in the presence of the solid catalyst layer, i.e. in situ. This is basically possible in two variants:

[0040] In a first variant, the textile fabric is impregnated with the ionomer solution by first placing the textile fabric onto the solid catalyst layer and then impregnating the textile fabric placed on the solid catalyst layer with the ionomer solution. In this variant, the textile is first positioned and then the ionomer solution is poured on.

[0041] In a second variant, the textile fabric is impregnated with the ionomer solution by first applying the ionomer solution to the solid catalyst layer and then immersing the textile fabric into the ionomer solution applied to the solid catalyst layer. In this variant, the ionomer solution is thus first poured on and then the textile is placed in.

[0042] Preferably, in the second variant, at least a portion of the second solvent is depleted from the ionomer solution applied to the solid catalyst layer before the textile fabric is immersed into the ionomer solution applied to the solid catalyst layer. This has the advantage that the textile fabric is not immersed as deeply into the fresh, but already partly dried ionomer layer. This creates a perpendicular distance between the catalyst layer and the textile, which increases the adhesion of the catalyst layer.

[0043] Preference is given to using a non-CMR-relevant solvent. Examples include dimethyl sulfoxide (DMSO), ethanol (EtOH), acetonitrile (ACN). The solvents can be used both as the first solvent in the catalyst ink and as the second solvent in the ionomer solution. Preference is given to using one of the substances mentioned for both solvents. 202400195 Foreign Filing 7

[0044] In a preferred embodiment of the process, the depletion of the first solvent and / or the second solvent from the fresh catalyst layer or from the fresh ionomer layer is incomplete. It follows that the solid catalyst layer or the solid ionomer layer has a residual solvent content. On separation of the transfer substrate from the solid catalyst layer, the residual solvent content should be between 5% and 30% by weight, based on the total mass of the solid catalyst layer or solid ionomer layer. In this way, detachment from the transfer substrate is facilitated.

[0045] In a preferred embodiment of the invention, the catalyst ink additionally contains a particulate inorganic material other than the electrocatalyst. To wit, this material can be used as a structuring agent that imparts porosity to the catalyst layer by first incorporating it into the catalyst layer and then removing it by leaching with aqueous alkaline solution and subsequent washing.

[0046] Suitable particulate inorganic materials are especially silicon dioxide (silica - SiO2) and aluminium oxide (alumina - AI2O3), and mixtures thereof (silica / alumina). Useful aqueous alkaline solutions include aqueous metal hydroxide solutions of sodium, potassium or lithium or a mixture thereof.

[0047] When the particulate inorganic material used is silicon dioxide and the aqueous metal hydroxide solution used is potassium hydroxide (KOH), the particulate silicon dioxide (SiO2) present in the catalyst layer is converted to the potassium silicate (foSiOs) and water (H2O) products:

[0048] SiO2+ 2 KOH K2SiO3+ H2O (1)

[0049] The potassium silicate product is water soluble and can be readily washed out of the catalyst layer. The same goes for the water product.

[0050] If a different alkali metal is used for leaching rather than potassium, for instance lithium or sodium, lithium silicate or sodium silicate is formed analogously to formula (1).

[0051] If the particulate inorganic material used is aluminium oxide (AI2O3), water-soluble aluminates are formed with the aqueous metal hydroxide solution. If, for example, the aqueous metal hydroxide solution used is sodium hydroxide (NaOH), according to formula (2), the product formed is sodium aluminate (NaAI(OH)4):

[0052] AI2O3 + 2 NaOH + 3 H2O 2 NaAI(OH)4(2)

[0053] Sodium aluminate is water-soluble and can be washed out easily.

[0054] It is also possible to simultaneously use particulate silica and particulate alumina or else mixed phases of the two. In that case, the above-described reactions proceed in parallel during the leaching, and multiple products are correspondingly obtained in parallel.

[0055] The silicates and / or aluminates present in the catalyst layer after the leaching can then be washed out of the catalyst layer with an aqueous solution, such that the catalyst layer becomes porous. The polymer 202400195 Foreign Filing 8 and the particulate electrocatalyst present in the catalyst layer remain unaffected by the leaching and washing and ultimately form the catalytically active layer of the finished laminate. The surface of the catalyst layer receives open pores as a result of the treatment, namely at the sites previously occupied by the inorganic particulate material.

[0056] The proportion by mass of the particulate inorganic material other than the electrocatalyst (for example silica / alumina) should be between 10% by weight and 40% by weight, based on the total mass of the dry catalyst layer.

[0057] The invention secondly provides an electrocatalytically active or activatable laminate as producible by the process of the invention or otherwise. Such a laminate has at least the following features: a) the laminate comprises at least one solid ionomer layer and at least one solid catalyst layer, where the solid ionomer layer and the solid catalyst layer are joined to one another via a boundary layer;

[0058] P) the solid catalyst layer comprises at least two phases, namely a first phase formed by at least one polymeric binder and a second phase formed by at least one particulate electrocatalyst, with the second phase dispersed in the first phase; y) the solid ionomer layer comprises a textile fabric fully or partly embedded in a matrix, where the textile fabric comprises a polymeric fibre material and the matrix is formed by at least one anion-conducting polymer;

[0059] 5) the polymeric fibre material has a first repeat unit comprising at least two phenylene groups;

[0060] 8) the anion-conducting polymer has a second repeat unit comprising at least two phenylene groups;

[0061] Q the first and second repeat units are identical or different.

[0062] The textile fabric preferably extends outside the boundary layer, i.e. with a certain perpendicular distance from the catalyst layer. This results in a better adhesion of the catalyst layer to the ionomer layer. Perpendicular direction relates to the plane of the textile fabric or of the catalyst layer.

[0063] However, the boundary layer should not become too thick. The thickness of the boundary layer is preferably less than 40% of the thickness s of the overall laminate.

[0064] The catalytically active or activatable laminate can be used as electrocatalytically active or activatable anion exchange membrane in an electrochemical process. The invention thirdly provides for such a use.

[0065] The laminate is preferably used in a process for producing hydrogen and oxygen by electrolysis of water in an alkaline environment (AEMWE). The use is effected in that the electrolysis is effected in the presence of the laminate. 202400195 Foreign Filing 9

[0066] The invention fourthly provides an electrolyser equipped with a laminate according to the invention.

[0067] With regard to all the subjects of the invention as presented here, the textile fabric is preferably a weave or a scrim or a loop-formed knit or a loop-drawn knit or a nonwoven.

[0068] It is likewise advantageous for all the subjects of the invention when the polymeric binder has a third repeat unit comprising at least two phenylene groups, where the second and third repeat units are identical or different, and where the first and third repeat units are identical or different. In this way, chemical similarity also arises between fibre material, ionomer and binder of the catalyst layer, which significantly increases the adhesion of the catalyst layer on the other components of the laminate.

[0069] For all subjects of the invention, it is preferable when the second repeat unit present in the anion- conducting polymer comprises at least two phenylene groups bonded via a single bond. Such ionomers are known, for example, from WO2024151961A1 (formula II) or from Figure 2 of WO 2019068051 A2.

[0070] Alternatively, the anion-conducting polymer and / or the polymeric fibre material each have at least one ether bridge that connects two aromatic six-membered rings, and optionally a sulfonyl group or a carbonyl group. The carbonyl group or the sulfonyl group can preferably connect two phenylene groups.

[0071] Examples of anion-conducting polymers having this structure can be found in EP3770201 B1 , EP4032934B1 and EP4059988A1.

[0072] Particular preference is given to using an anion-conducting polymer and / or a polymeric binder having the following structure (I): in which X in (I) is the carbonyl or sulfonyl group; in which Y in (I) is a structural element comprising a nitrogen atom having a positive charge which is bonded to C1and C2and bonded via two bonds to one or two hydrocarbon radicals having one to twelve or one to six or one to five carbon atoms, 202400195 Foreign Filing 10 in which R1, R2, R3and R4in (I) are identical or different alkyl groups having one to four carbon atoms.

[0073] An alternative is to use an anion-conducting polymer and / or a polymeric binder having the following structure (I): in which X in (II) is the carbonyl or sulfonyl group; in which Y in (II) is a structural element comprising a nitrogen atom having a positive charge, in which R1, R2, R3and R4in (II) are identical or different alkyl groups having one to four carbon atoms.

[0074] The polymers having the structures (I) and (II) are suitable both as ionomer in the ionomer layer and as binder in the catalyst layer.

[0075] The fibre material is particularly preferably a polyetherketone (PEK), polyetheretherketone (PEEK) or sulfonated polyetheretherketone (SPEEK) or partly sulfonated polyetheretherketone (SPEEK). Since the polymer class of the polyetherketones each have a repeat unit with at least two phenylene groups, they form a particularly strong bond with the abovementioned ionomers.

[0076] The laminate should be as gas-tight as possible, so that the two gases, hydrogen and oxygen, formed in water electrolysis do not diffuse through the laminate and mix to form explosive gas. The gas permeability of porous materials can be determined according to ISO 5636-5:2013 in terms of the Gurley value. The Gurley value describes the time taken for a defined amount of gas to diffuse through a defined area of the porous substance. The higher the Gurley value, the greater the gas-tightness of the fabric. The laminate should have a Gurley value of more than 16 h determined in accordance with ISO 5636-5:2013. This means that the laminate is sufficiently gas-tight.

[0077] Such gas-tightness requires that the textile is embedded sufficiently deep in the ionomer layer, such that the textile pores are closed by the ionomer. Moreover, the ionomer layer should have a certain minimum thickness. The catalyst layer, on the other hand, makes no contribution to gas-tightness because it should be porous in order to keep the catalytically active centres accessible to the electrolyte. 202400195 Foreign Filing 11

[0078] With regard to the dimensions of catalyst layer and ionomer layer, it is advantageous to observe the following relationships:

[0079] 0.05*s < k < 0.4*s and

[0080] 1.5*k < / < 15*k

[0081] In these formulae, s represents the thickness of the whole laminate, k represents the thickness of the catalyst layer and / represents the thickness of the ionomer layer. The total thickness s of the laminate should be within a range of 40 pm to 100 pm.

[0082] In a preferred embodiment of the invention, the textile fabric is not compressed down to the catalyst layer, such that a distance between the textile fabric and the catalyst layer is maintained, where the distance is aligned perpendicularly to the plane of the textile fabric or the catalyst layer. In this way, an interface layer is formed between the ionomer layer and the catalyst layer, which is free of the textile fabric and free of the electrocatalyst. The boundary layer is formed by the ionomer. The boundary layer should have a thickness g within the following range:

[0083] 0.01*s < g < 0.4*s in which s again represents the total thickness of the laminate.

[0084] The textile fabric may have been subjected to treatment with a corona electrode. In this way, its surface energy and hence its wettability increases. Since the effect of this measure lasts for a limited period of time, the corona treatment should be carried out as late as possible before the impregnation of the textile with the ionomer.

[0085] 202400195 Foreign Filing 12 of the figures

[0086] The invention will now be explained in detail with reference to figures. For this purpose, the figures show, in schematic form:

[0087] Fig. 1 : applying of catalyst layer;

[0088] Fig. 2: fresh catalyst layer;

[0089] Fig. 3: drying the catalyst layer;

[0090] Fig. 4: solid catalyst layer;

[0091] Fig. 5: applying ionomer layer;

[0092] Fig. 6: fresh ionomer layer;

[0093] Fig. 7: inserting textile fabric;

[0094] Fig. 8: drying ionomer layer;

[0095] Fig. 9: detaching transport substrate;

[0096] Fig. 10: final laminate.

[0097] First of all, a transfer substrate 1 is provided. The transfer substrate is, for example, a flat glass plate or a polyethylene terephthalate (PET) film.

[0098] In addition, a catalyst ink 2 is provided. This is a multiphase mixture comprising the actual electrocatalyst 3 in particulate solid form. For example, the electrocatalyst 3 is a standard Pt / C catalyst. This is, for example, a graphite carrier spiked with platinum. A further constituent present in the catalyst ink 2 is a polymeric binder 4, dissolved in a first solvent 5. The solid particulate electrocatalyst 3 and the liquid dissolved binder 4 impart an overall viscous to pasty consistency to the catalyst ink 2. The catalyst ink 2 may also contain other additives that need not be described in detail here.

[0099] The catalyst ink 2 is applied to the transfer substrate 1 . This can be done, for example, by a squeegee process.

[0100] After application, there is a fresh catalyst layer 6 on one side of the transfer substrate 1 ; cf. Figure 2. 202400195 Foreign Filing 13

[0101] The fresh catalyst layer 6 is subjected to drying, with the evaporation of at least a portion of the first solvent 5 from the fresh catalyst layer 6 (Figure 3). This results in precipitation of the binder 4 out of the solution and formation of a solid phase that encloses the electrocatalyst 3.

[0102] When the drying is complete (Figure 4), a solid catalyst layer 7 is present on the transfer substrate and comprises two phases, namely a first phase formed by the now solid binder 4 and a second phase formed by the particulate electrocatalyst 3. The second phase is dispersed in the first phase.

[0103] Then a liquid to pasty ionomer solution 8 is provided. The ionomer solution comprises an anion- conducting polymer 9 dissolved in a second solvent 10. The second solvent 10 of the ionomer solution 8 may be the same substance as the first solvent 5 of the catalyst ink 2. It is alternatively possible to use different solvents 5, 10.

[0104] The liquid catalyst ink 2 is applied to the solid catalyst layer 7, for example by squeegeeing or spraying (Figure 5). In this way, a fresh ionomer layer 11 (Figure 6) is formed on the solid catalyst layer 7.

[0105] Then a textile fabric 12 is provided. The textile fabric 12 may be, for example, a weave or a nonwoven. It comprises fibres of a polymeric fibre material having chemical similarity to the still-dissolved anion- conducting polymer 9 present in the fresh ionomer layer 11 . The similarity is the presence of two phenylene groups in a repeat unit of both the fibre polymer and the ionomer.

[0106] The textile fabric 12 is now placed into the still-fresh ionomer layer 11 (Figure 7), such that the textile fabric 12 is impregnated with the ionomer solution 8. Owing to the capillary effect, the pores of the textile fabric 12 become filled with ionomer solution 8. The capillary effect was previously increased by a corona treatment of the textile fabric 12. It is important that the impregnating is effected in the presence of the solid catalyst layer 7. This is achieved in the process variant shown in Figure 7 in that the fresh ionomer layer 11 is already on the solid catalyst layer 7 when the textile fabric 12 is impregnated with the ionomer solution 8. Alternatively, it is possible to apply the textile fabric 12 to the still-uncoated solid catalyst layer 7 and only then pour on the ionomer solution 8. This creates the fresh ionomer layer 11 during impregnation.

[0107] Irrespective of the sequence of layer formation and impregnation, the fresh ionomer layer 11 is subjected to drying with the textile fabric 12 present therein, with the evaporation of at least a portion of the second solvent 10 out of the fresh ionomer layer 11 (Figure 8). As a result, the anion-conducting polymer 9 precipitates out of the solution and forms a solid ionomer layer 13 on the solid catalyst layer 7. The textile fabric 12 is embedded here in the solid ionomer layer 13. The chemical similarity between polymeric fibre material and anion-conducting polymer 9 means that a strong bond is created between the solid ionomer layer 13 and the textile fabric 12. The solid ionomer layer 13 and the solid catalyst layer 7 are contacted directly with one another via a boundary layer 14. The boundary layer 14 is ideally infinitesimally thin, but will in practice constitute a transition region, especially when the second solvent 10 present in the ionomer solution 8 is able to dissolve the binder 4 present in the solid catalyst layer 7. 202400195 Foreign Filing 14

[0108] Then the solid catalyst layer 7 is detached from the transfer substrate 1 . This can also be done earlier, for example after the drying of the fresh catalyst layer 6 and before the applying of the fresh ionomer layer (after Figure 3 and before Figure 5). It is also possible to detach the transfer substrate 1 when the fresh catalyst layer 6 is not yet completely dried (during Figure 3). This has the advantage that the transfer substrate 1 can then be removed even more easily.

[0109] The result is a laminate 15 comprising at least the solid catalyst layer 7 and the solid ionomer layer 13 with the textile fabric embedded therein 13. As can be seen in the figures, the textile fabric 12 is embedded not completely but only partly into the solid ionomer layer 13. Some of the fibres protrude at the top. Because of its transition character, the boundary layer 14 is not an independent part of laminate 15. Its thickness g is close to zero. Since the transfer substrate 1 has been detached, this likewise does not form a part of the laminate 15.

[0110] The solid ionomer layer 13 of the laminate forms a closed anion-conducting layer and therefore functions as an anion exchange membrane. The particulate electrocatalyst present in the solid catalyst layer 7 gives the laminate 15 its catalytic activity. The electrocatalyst 3 is immobilized via the binder 4 on the membrane / ionomer layer 13. The whole laminate and in particular the ionomer layer 13 is mechanically reinforced by means of the textile fabric 12.

[0111] Since the textile fabric 12 partly protrudes from the solid ionomer layer 13, the sum of the thickness / of the solid ionomer layer 13 and the thickness k of the solid catalyst layer 7 is less than the thickness s of the whole laminate. By contrast to what is shown in Figure 10, the thickness i of the solid ionomer layer 13 may also be greater than the thickness k of the solid catalyst layer 7. The thickness s of the whole laminate 15 is in the range from about 50 pm to 100 pm.

[0112] 202400195 Foreign Filing 15

[0113] The effects achieved by the invention will now be demonstrated experimentally. In this regard, the figures show:

[0114] Figure 11 : Strain-stress characteristics of various laminates;

[0115] Figure 12: Current-voltage characteristics of various laminates;

[0116] Figure 13: Photograph of laminate C (not according to the invention) after electrolysis;

[0117] Figure 14: Photograph of laminate D with reinforcing weave after electrolysis;

[0118] Figure 15: Photograph of laminate E with reinforcing weave and silica after electrolysis;

[0119] Figure 16: SEM image of laminate according to the invention in side view;

[0120] Figure 17: SEM image of laminate according to the invention in bottom view;

[0121] Figure 18: SEM image of laminate according to the invention in enlarged side view;

[0122] Figure 19: Line profile of conventionally produced laminates (Example 8);

[0123] Figure 20: 3D representation of surface of catalyst layer of conventionally produced laminates (Example 8);

[0124] Figure 21 : Line profile of laminate produced in accordance with the invention (Example 10);

[0125] Figure 22: 3D representation of surface of catalyst layer of laminates produced in accordance with the invention (Example 10).

[0126] Figure 23: Photograph of a droplet of a polymer solution (22 wt% in DMSO) applied to an ePTFE sheet (left) and to a PEEK sheet (right), both sheets being placed on a paper sheet (Example 16).

[0127] Figure 24: Photograph of the repositioned ePTFE sheet (left) and PEEK fabric (right) one minute after application of the polymer solution (22 wt% in DMSO), showing no residue on the paper beneath the ePTFE sheet and visible absorption of the solution on the paper beneath the PEEK fabric (Example 16). 202400195 Foreign Filing 16

[0128] Table 1 provides an overview of the laminates produced in Examples 6 to 9:

[0129] Table 1 : Overview of the laminates produced

[0130] 1. Preparation of an ionomer (not part of the invention)

[0131] An anion-conducting cationic polymer was synthesized in accordance with Example 3 of EP3770201A1. This was then dried in a vacuum drying oven at 60°C for 7 days. This was then used to make up a 5 wt% solution in DMSO. For this purpose, 5 parts by weight of the dry polymer was placed in a vessel and 95 parts by weight of DMSO was added. The vessel was tightly closed and the contents were stirred at 60°C for 2 days using a magnetic stirrer at 100 RPM.

[0132] 2. Production of an anion exchange membrane (not part of the invention)

[0133] Then the cationic polymer synthesized in 1. was used to produce an anion-conducting membrane as described in Example 4 of EP3770201A1 .

[0134] 3. Providing a catalyst ink without silica (part of the invention)

[0135] A screw-cap jar was filled up to one third with yttrium-stabilized zirconium oxide grinding balls (diameter 5 mm). Subsequently, two parts by weight of catalyst powder (platinum on carbon, 50% platinum loading) was introduced into the vessel. Thereafter, 19 parts by weight of water was added, the jar cap was closed, and the jar was agitated by means of a “lab dancer” vortex agitator (I KA) for one minute. The vessel was opened again, 19 parts by weight of ethanol was added, and the vessel was closed again and agitated again for one minute. Subsequently, the vessel was alternately placed on a tilt-and-roll mixer at 60 rpm for at least five hours and into an ultrasound bath (180 W) for five minutes. This was repeated twice. 76 parts of water and 76 parts of ethanol were added in each case, and the mixture was agitated by vortex agitator for one minute. Lastly, an ionomer solution (5% ionomer in DMSO; as produced in 1 .) was added until the solids content of the ionomer accounted for 14% of the total solids content, the vessel was closed, and the solution was rolled on the tilt-and-roll mixer for one hour and finally placed in an ultrasound bath at 180 W for five minutes. 202400195 Foreign Filing 17

[0136] 4. Providing a catalyst ink with silica (part of the invention)

[0137] The production using silica was largely analogous to the production of the comparative ink described above in 3., except that the silica was additionally added in the course of the last addition of water and ethanol:

[0138] The screw-cap jar was filled up to one third with yttrium-stabilized zirconium oxide grinding balls (diameter 5 mm). Subsequently, two parts by weight of catalyst powder (platinum on carbon, 50% platinum loading) was introduced into the vessel. Thereafter, 19 parts by weight of water was added, the jar cap was closed, and the jar was agitated by means of a “lab dancer” vortex agitator (I KA) for one minute. The vessel was opened again, 19 parts by weight of ethanol was added, and the vessel was closed again and agitated again for one minute. Subsequently, the vessel was alternately placed on a tilt-and-roll mixer at 60 rpm for at least five hours and into an ultrasound bath (180 W) for five minutes. This was repeated twice. 0.6 parts by weight of silica and 76 parts of water and 76 parts of ethanol were added in each case, and the mixture was agitated by vortex agitator for 1 minute. The silica was added in the form of a silica having a BET surface area of 300 m2 / g (AEROSIL® 300), in dispersion in water with solids content 10%. The amount of water in the dispersion was taken into account in the total amount of water added.

[0139] Lastly, ionomer solution (5% ionomer produced according to 1 ., dissolved in DMSO) was added until the solids content of the ionomer accounted for 14% of the total solids content, the vessel was closed, and the solution was rolled on the tilt-and-roll mixer for one hour and finally placed in an ultrasound bath at 180 W for five minutes.

[0140] 5. Coating the transfer substrate with the silica-containing catalyst ink (part of the invention)

[0141] For the inventive experiment (with silica), the ink provided in 4. was applied to a transfer substrate using a spray coater. The transfer substrate was a PET film. During the coating, the PET film was fixed on a surface heated to 60°C.

[0142] The coating parameters were adapted to achieve a homogeneous platinum area density of 0.45 mgpt / cm2with about 90 coats. It was ensured that each individual coat was largely dried before the respective next coat was applied. Lastly, the coated PET film was subjected to final drying on the heated surface for 30 minutes.

[0143] This afforded a PET film provided with a dry catalyst layer containing silica.

[0144] 6. Producing an unreinforced laminate A (not part of the invention)

[0145] The cationic polymer synthesized in 1 . was used to apply an ionomer layer to the silica-containing catalyst layer of the PET film obtained in 5. This operation was effected as in Example 4 of EP3770201 A1 , except 202400195 Foreign Filing 18 that in the present case the catalyst-coated PET film obtained in 5. was used rather than an uncoated glass sheet.

[0146] Drying the ionomer layer afforded a laminate A comprising the silica-containing catalyst layer and the ionomer layer applied thereto. The laminate was carefully detached from the PET film with the aid of water.

[0147] Laminate A is already usable in alkaline water electrolysis like a conventional catalytically active anion exchange membrane. In order to achieve maximum efficiency, however, a forming step is required, but this may also be performed in an electrolysis cell. In this case, the leaching was performed prior to incorporation into the electrolysis test cell. For this purpose, the laminate was placed in 1 M KOH at room temperature for 3 hours.

[0148] 7. Conventionally produced unreinforced laminate B comprising silica

[0149] (not part of the invention)

[0150] For the experiment with silica, the catalyst ink provided in 4. was applied to a substrate by means of a spray coater. The substrate is the anion-conducting membrane provided in 2. During the coating, the membrane was fixed on a surface heated to 60°C.

[0151] The coating parameters were adjusted in order to achieve a homogeneous platinum area loading of 0.45 mgpt / cm2with about 90 layers. It was ensured that each individual layer was largely dry before the respective next layer was applied. Lastly, the coated membrane was finally dried on the heated surface for 30 minutes.

[0152] In this way, a laminate B was obtained. The laminate B is a CCM that can be used in alkaline water electrolysis. For better comparability, the leaching here too was conducted prior to incorporation in the electrolysis test cell. For this purpose, the laminate was placed in 1 M KOH at room temperature for 3 hours.

[0153] 8. Conventionally produced reinforced laminate C comprising silica

[0154] For this purpose, a weave-reinforced membrane was first produced.

[0155] For this purpose, the cationic polymer synthesized in 1. was used to apply an ionomer layer to a PET film. This operation was effected as described in example 4 of EP3770201 A1 , except that a PET film was used rather than an uncoated glass plate.

[0156] A PEEK reinforcing weave (fibre diameter 40 pm, open area 70%) was pressed two-dimensionally into the fresh polymer layer that later forms the membrane, and the resulting reinforced membrane body was dried.

[0157] Subsequently, analogously to Example 7, a laminate C was produced, except using the reinforced AEM membrane body. 202400195 Foreign Filing 19

[0158] 9. Production of a reinforced laminate D (inventive)

[0159] The catalyst ink provided in 3. was applied to a transfer substrate in several layers by means of a spray coater. The transfer substrate was a planar glass sheet. During the coating, the PET film was secured to a heated (60°C) surface.

[0160] The coating parameters were adapted to achieve a homogeneous platinum area density of 0.45 mgpt / cm2with about 90 coats. It was ensured that each individual coat was largely dried before the respective next coat was applied. Lastly, the coated glass sheet subjected to a final drying on the heated surface for 30 minutes.

[0161] This afforded a PET film provided with a dry catalyst layer.

[0162] Then the cationic polymer synthesized in 1 . was used to apply an ionomer layer to the dry catalyst layer of the PET film. This operation was effected as in Example 4 of EP3770201A1 , except that the catalyst-coated PET film obtained here was used rather than an uncoated glass sheet.

[0163] A PEEK reinforcing weave (fibre diameter 40 pm, open area 70%) was pressed two-dimensionally into the fresh ionomer layer that later forms the membrane.

[0164] Drying the ionomer layer afforded a laminate D comprising the catalyst layer and the ionomer layer with embedded PEEK reinforcing weave applied thereto. After the ionomer had been dried, the reinforcing weave became part of the laminate, supporting it and strengthening it mechanically. Laminate D was carefully detached from the PET film.

[0165] 10. Production of a reinforced laminate E comprising silica (inventive)

[0166] The silica-containing catalyst ink provided in 4. was applied to a transfer substrate in several layers by means of a spray coater. The transfer substrate was a planar PET film. During the coating, the PET film was secured to a heated (60°C) surface.

[0167] The coating parameters were adapted to achieve a homogeneous platinum area density of 0.45 mgpt / cm2with about 90 coats. It was ensured that each individual coat was largely dried before the respective next coat was applied. Lastly, the coated glass sheet subjected to a final drying on the heated surface for 30 minutes.

[0168] This afforded a PET film provided with a dry catalyst layer.

[0169] Then the cationic polymer synthesized in 1 . was used to apply an ionomer layer to the dry catalyst layer of the PET film. This operation was effected as in Example 4 of EP3770201A1 , except that the catalyst-coated PET film obtained here was used rather than an uncoated glass sheet. 202400195 Foreign Filing 20

[0170] A PEEK reinforcing weave (fibre diameter 40 pm, open area 70%) was pressed two-dimensionally into the fresh ionomer layer that later forms the membrane.

[0171] Drying the ionomer layer afforded a laminate E comprising the silica-containing catalyst layer and the ionomer layer with embedded PEEK reinforcing weave applied thereto. After the ionomer had been dried, the reinforcing weave became part of the laminate, supporting it and strengthening it mechanically. Laminate E was carefully detached from the PET film. For better comparability, the leaching here too was conducted prior to incorporation in the electrolysis test cell. For this purpose, the laminate was placed in 1 M KOH at room temperature for 3 hours.

[0172] 11. Study of the mechanical properties of the wet laminates

[0173] Three 6 cm x 1 cm test strips were cut from each of laminates A, B, D and E and placed in deionized water for 1 hour. In this way, a swollen state similar to that in use was simulated. Subsequently, the test strips were tested individually under the same conditions using a tensile tester (ZwickRoell). The (average) characteristic strain-stress characteristics are shown in Figure 11 . It is apparent here that the standard force of laminate A (long-dashed line) is the lowest in the entire strain regime, which suggests that its mechanical durability is relatively low. Laminate B has significantly higher forces for the same expansion (short-dashed line). However, the force already reaches a plateau at an elongation of ~3% and a standard force of 18.5 MPa and then the material starts to exhibit viscoelastic characteristics. Laminate D (solid line) and laminate E (dotted line) have a significantly increased standard force, especially at strains of > 3%, compared to those of the two unreinforced laminates. This shows that the problem of poor mechanical properties has been solved using the inventive approach.

[0174] 12. Assessment of suitability of the laminates produced in accordance with the invention in water electrolysis

[0175] For this purpose, laminates C, D and E were tested in AEM water electrolysis.

[0176] The coated and leached laminates were tested in an electrolysis test cell with an active Pt / C catalyst- coated area of 25 cm2. The catalyst layer served here as cathode catalyst. On the anode side, a dimensionally stable, porous stainless steel electrode was used. During the electrolysis experiments, the measurement cell was heated to 60°C and flushed with 1 M KOH solution on the anode and cathode sides. The current-voltage characteristic is recorded in Figure 12. The characteristics are labelled for the respective laminates. It is apparent that the electrical voltage at the same current is relatively similar for laminates C, D and E, whereas laminate D (without silica), as would be expected, is slightly higher, which means a somewhat lower electrolysis efficiency. Nonetheless, all the laminates produced are suitable as a membrane-electrode assembly for water electrolysis. 202400195 Foreign Filing 21

[0177] 13. Testing the stability of the catalyst layer after electrolysis

[0178] For this purpose, laminates C, D and E were placed onto a flat substrate after the AEM water electrolysis test. Subsequently, a cotton bud was used to test whether or how much catalyst can be rubbed off when it is used to rub the catalyst layer over a length of 5 mm with a force (vertically to the catalyst layer) of 1.3 N. The results are shown in Figure 13 (laminate C), Figure 14 (laminate D) and Figure 15 (laminate E). It is apparent that the laminates produced in accordance with the invention have improved binding of the catalyst to the membrane, which can mean an elevated lifetime of the unit for prolonged electrolysis use.

[0179] 14. Study of the roughness of the laminates produced

[0180] Since the intended use, namely AEM water electrolysis, involves contacting the catalyst layer with a porous, electrically conductive transport layer, the surface morphology of the catalyst layer is crucial for a good mechanical and electrical connection of the two layers. What is desirable for this purpose is minimum roughness in order to assure a homogeneous pressure distribution and to minimize mechanical stress. Therefore, the surface roughness of the catalyst layer of a conventionally produced reinforced laminate as described in Example 8 was analysed in accordance with DIN ISO 11562. For this purpose, an area of 5.2 mm x 5.2 mm was examined by convocal microscopy (MarSurf CM Explorer, Mahr GmbH, Germany) and evaluated using the accompanying software (MarSurf MFM Extended 7.4.8737). This was done using a wave filter (Gaussian filter 800 pm, cut-off 2.5 pm) suitable for expected average roughness values Rain the 0.1 pm to 2.0 pm range. A representative line profile is shown in Figure 19. Average roughness was determined in accordance with DIN EN ISO 4287: Ra= 1 .68 ± 0.39 pm. Surface roughness was determined in accordance with ISO 25178: Sa= 1 .85 ± 0.34 pm. Figure 20 shows a representative detail of the 3D surface.

[0181] The same procedure was used to examine the surface roughness of the catalyst layer of an (inventive) laminate produced as described in Example 10. A representative line profile is shown in Figure 21 ; average roughness was determined in accordance with DIN EN ISO 4287: Ra= 0.137 ± 0.013 pm. Figure 22 shows a representative detail of the 3D surface; surface roughness was determined in accordance with ISO 25178: Sa= 0.137 ± 0.056 pm. Comparison of the measured parameters makes it clear that the roughness of the catalyst layer of the inventively produced laminates (from Example 10) is significantly lower, by about one order of magnitude, than that of the conventionally produced laminate (from Example 8). The line profiles or the 3D details illustrate this relationship.

[0182] 15. Study of gas permeability of the inventively produced laminate

[0183] For use in AEM water electrolysis, it is important that the two gases (hydrogen and oxygen) formed in the electrolysis are unable to mix significantly at the respective electrode. For this purpose, a certain gastightness vertically to the plane of the laminate is required. In order to check whether significant defects exist in the form of continuous holes through the ionomer layer, the air permeability of a laminate 202400195 Foreign Filing 22 produced as in Example 10 was conducted by Gurley densometer (Gurley Precision Instruments). This test is especially suitable for materials with air permeability in the range between 0.1 pm / (Pa-s) and 100 pm / (Pa-s). The Gurley value ascertained indicates the number of seconds taken for 100 cm3of gas to diffuse through an area of one inch2(25.4 mm*25.4 mm = 645.16 mm2). Before testing, the measuring instrument was calibrated with a test material. For the composite, however, it was not possible to ascertain a Gurley value because it was too impervious and the volume of 100 ml had not diffused through the test body even after 24 hours. This indicates a sufficiently high gas-tightness of the laminates according to the invention.

[0184] 16. Study of wettability of different reinforcement fabrics

[0185] The suitability of two different textile reinforcements was evaluated, namely of expanded polytetrafluoroethylene (ePTFE) and PEEK. For effective embedding of the reinforcement into the membrane polymer, compatibility between the materials is crucial. Rapid and thorough wetting is particularly important, as it facilitates a swift production process with minimal trapped air bubbles, which could compromise the membrane's properties.

[0186] An anion-conducting cationic polymer was synthesized in accordance with Example 3 of EP3770201A1. This was then dried in a vacuum drying oven at 60°C for 7 days. This was then used to make up a 22 wt% solution in DMSO. For this purpose, 22 parts by weight of the dry polymer was placed in a vessel and 78 parts by weight of DMSO was added. The vessel was tightly closed, and the contents were stirred at 60°C for 2 days using a magnetic stirrer at 100 RPM.

[0187] A droplet of the polymer solution (22 wt% in DMSO) was applied to an ePTFE sheet (1 .5 pm pore size; commercially available from sigma Aldrich (Germany)) (Fig. 23, left) and a PEEK reinforcing weave (fibre diameter: 40 pm; open area: 70%) (Fig. 23, right). Beneath the sheets, a piece of paper was positioned. After one minute, both the ePTFE and PEEK sheets were lifted and moved a few centimeters upward on the paper.

[0188] As illustrated in Fig. 24 (left), the polymer solution did not penetrate the ePTFE sheet, as indicated by the absence of residue on the underlying paper, confirming incomplete permeation / wetting. In contrast, the polymer solution readily wetted the PEEK fabric and permeated through it, as evidenced by the presence of absorbed solution on the underlying paper (see Fig. 24, right).

[0189] In contrast to ePTFE, the PEEK fabric demonstrated superior wetting properties for the polymer solution making it significantly more suitable as a reinforcement material.

[0190] 17. Conclusion

[0191] It can clearly be seen that the inventive embedding of the weave has significantly improved the laminates in terms of their mechanical properties. Furthermore, suitability for AEM water electrolysis was shown, 202400195 Foreign Filing 23 and it was possible in particular in the case of production with silicon dioxide in the catalyst layer to achieve strains virtually identical to conventionally coated, reinforced laminates (produced with silicon dioxide). Ultimately, however, the inventively produced membranes additionally had improved adhesion of the catalyst even after electrolysis, which suggests an elevated lifetime of the inventively produced laminates.

[0192] Figures 16, 17 and 18 show scanning electron micrographs of the laminate E.

[0193] In particular, it can be seen from Figure 16 that the process according to the invention achieves a solid catalyst layer 7 with good planarity. The reason for this is the application of the catalyst layer to the flat glass plate.

[0194] In particular, it can be seen from Figure 18 that it is possible by the process according to the invention to integrate the textile fabric 12 into the middle of the solid ionomer layer 13.

[0195] 202400195 Foreign Filing 24

[0196] List of reference symbols

[0197] 1 transfer substrate

[0198] 2 catalyst ink

[0199] 3 electrocatalyst

[0200] 4 binder

[0201] 5 first solvent

[0202] 6 fresh catalyst layer

[0203] 7 solid catalyst layer

[0204] 8 ionomer solution

[0205] 9 anion-conducting polymer

[0206] 10 second solvent

[0207] 11 fresh ionomer layer

[0208] 12 textile fabric

[0209] 13 solid ionomer layer

[0210] 14 boundary layer

[0211] 15 laminate k thickness of the solid catalyst layer i thickness of the solid ionomer layer g thickness of the boundary layer s thickness of the whole laminate

Claims

202400195 Foreign Filing 25Claims1 . Process for producing an electrocatalytically active or activatable laminate, comprising the following non-chronological steps: a) providing a transfer substrate; b) providing a catalyst ink comprising at least one first solvent, at least one polymeric binder dissolved in the first solvent, and at least one particulate electrocatalyst; c) applying the catalyst ink to the transfer substrate to form a fresh catalyst layer on the transfer substrate; d) depleting the first solvent from the fresh catalyst layer so as to form, on the transfer substrate, a solid catalyst layer comprising at least two phases, namely a first phase which is formed by the now undissolved polymeric binder and a second phase which is formed by the particulate electrocatalyst, where the second phase is dispersed in the first phase; e) optionally: separating the transfer substrate from the solid catalyst layer; f) providing an ionomer solution comprising at least one second solvent and at least one anion-conducting polymer dissolved in the second solvent, where the first and second solvents are identical or different; g) providing a textile fabric comprising fibres of a polymeric fibre material; h) impregnating the textile fabric with the ionomer solution in the presence of the solid catalyst layer so as to form, on the solid catalyst layer, a fresh ionomer layer comprising the textile fabric impregnated with the ionomer solution; i) depleting the second solvent from the fresh ionomer layer so as to form, on the solid catalyst layer, a solid ionomer layer comprising the textile fabric and the now undissolved anion-conducting polymer, where the textile fabric is completely or partly embedded in a matrix formed by the anion-conducting polymer; k) if not yet done: separating the transfer substrate from the solid catalyst layer; l) obtaining the electrocatalytically active or activatable laminate, where the laminate comprises the solid catalyst layer and the solid ionomer layer applied thereto; wherein the textile fabric and the ionomer solution are provided with the proviso that202400195 Foreign Filing 26 the polymeric fibrous material has a first repeat unit comprising at least two phenylene groups, and the anion-conducting polymer has a second repeat unit comprising at least two phenylene groups, where the first and second repeat units are identical or different.

2. Process according to Claim 1 , characterized in that the textile fabric is impregnated with the ionomer solution by first placing the textile fabric onto the solid catalyst layer and then impregnating the textile fabric applied to the solid catalyst layer with the ionomer solution.

3. Process according to Claim 1 , characterized in that the textile fabric is impregnated with the ionomer solution by first applying the ionomer solution to the solid catalyst layer and then immersing the textile fabric into the ionomer solution that has been applied to the solid catalyst layer.

4. Process according to Claim 3, characterized in that at least a portion of the second solvent is depleted from the ionomer solution applied to the solid catalyst layer before the textile fabric is immersed into the ionomer solution applied to the solid catalyst layer.

5. Process according to any of Claims 1 to 4, characterized in that the first solvent and the second solvent are selected identically or differently from the group consisting of the following solvents: dimethyl sulfoxide (DMSO), ethanol (EtOH), acetonitrile (ACN).

6. Process according to any of Claims 1 to 5, characterized in that the first solvent and / or the second solvent is depleted incompletely from the fresh catalyst layer or from the fresh ionomer layer, in such a way that the solid catalyst layer or the solid ionomer layer has a residual solvent content, where the residual solvent content on separation of the transfer substrate from the solid catalyst layer is between 5% by weight and 30% by weight, based on the total mass of the solid catalyst layer or the solid ionomer layer.

7. Process according to any of Claims 1 to 6, characterized in that the catalyst ink additionally comprises a particulate inorganic material other than the electrocatalyst.

8. Process according to Claim 7, characterized in that the particulate inorganic material comprises silicon dioxide and / or aluminium oxide.

9. Process according to Claim 7 or 8, characterized in that the proportion by mass of the particulate inorganic material other than the electrocatalyst is between 10% by weight and 40% by weight, based on the total mass of the dry catalyst layer.202400195 Foreign Filing 2710. Electrocatalytically active or activatable laminate having at least the following characteristics: a) the laminate comprises at least one solid ionomer layer and at least one solid catalyst layer, where the solid ionomer layer and the solid catalyst layer are joined to one another via a boundary layer;P) the solid catalyst layer comprises at least two phases, namely a first phase formed by at least one polymeric binder and a second phase formed by at least one particulate electrocatalyst, with the second phase dispersed in the first phase; y) the solid ionomer layer comprises a textile fabric fully or partly embedded in a matrix, where the textile fabric comprises a polymeric fibre material and the matrix is formed by at least one anion-conducting polymer;5) the polymeric fibre material has a first repeat unit comprising at least two phenylene groups;8) the anion-conducting polymer has a second repeat unit comprising at least two phenylene groups;Q the first and second repeat units are identical or different.11 . Electrocatalytically active or activatable laminate according to Claim 10, characterized in that the textile fabric extends outside the boundary layer.

12. Electrocatalytically active or activatable laminate according to Claim 10 or 11 , characterized in that the thickness of the boundary layer is less than 30% of the thickness s of the whole laminate.

13. Process according to any of Claims 1 to 9 or electrocatalytically active or activatable laminate according to any of Claims 10 to 12, characterized in that the textile fabric is a weave or a scrim or a loop-formed knit or a loop-drawn knit or a nonwoven.

14. Process according to any of Claims 1 to 9 and 13 or electrocatalytically active or activatable laminate according to any of Claims 10 to 13, characterized in that the polymeric binder has a third repeat unit comprising at least two phenylene groups, where the second and third repeat units are identical or different, and where the first and third repeat units are identical or different.

15. Process according to any of Claims 1 to 9 and 13 to 14 or electrocatalytically active or activatable laminate according to any of Claims 10 to 14, characterized in that the second repeat unit comprises at least two phenylene groups joined via a single bond.

16. Process according to any of Claims 1 to 9 and 13 to 15 or electrocatalytically active or activatable laminate according to any of Claims 10 to 15, characterized in that202400195 Foreign Filing 28 the anion-conducting polymer and / or the polymeric fibre material each have at least one ether bridge that connects two aromatic six-membered rings, and optionally a sulfonyl group or a carbonyl group.

17. Process according to Claim 16 or electrocatalytically active or activatable laminate according to Claim 16, characterized in that the carbonyl group or the sulfonyl group connects two phenylene groups.

18. Process according to any of Claims 1 to 9 and 13 to 17 or electrocatalytically active or activatable laminate according to any of Claims 10 to 17, characterized in that the fibre material is polyetherketone (PEK), polyetheretherketone (PEEK) or sulfonated polyetheretherketone (SPEEK) or partly sulfonated polyetheretherketone (SPEEK).

19. Process according to any of Claims 16 to 18 or electrocatalytically active or activatable laminate according to any of Claims 16 to 18, characterized in that the anion-conducting polymer and / or the polymeric binder has the following structure (I):in which X in (I) is the carbonyl or sulfonyl group; in which Y in (I) is a structural element comprising a nitrogen atom having a positive charge which is bonded to C1and C2and bonded via two bonds to one or two hydrocarbon radicals having one to twelve or one to six or one to five carbon atoms, in which R1, R2, R3and R4in (I) are identical or different alkyl groups having one to four carbon atoms.

20. Process according to any of Claims 16 to 18 or electrocatalytically active or activatable laminate according to any of Claims 16 to 18, characterized in that the anion-conducting polymer and / or the polymeric binder has the following structure (II):202400195 Foreign Filing 29in which X in (II) is the carbonyl or sulfonyl group; in which Y in (II) is a structural element comprising a nitrogen atom having a positive charge, in which R1, R2, R3and R4in (II) are identical or different alkyl groups having one to four carbon atoms.21 . Process according to any of Claims 1 to 9 and 13 to 20 or electrocatalytically active or activatable laminate according to any of Claims 10 to 20, characterized in that the laminate has a Gurley value over 16 h that has been determined in accordance with ISO 5636-5:2013.

22. Process according to any of Claims 1 to 9 and 13 to 21 or electrocatalytically active or activatable laminate according to any of Claims 10 to 21 , wherein the solid catalyst layer has a thickness k, and wherein the solid ionomer layer has a thickness / , characterized in that the thicknesses are subject to the following relationships:0.05*s < k < 0.4*s and1.5*k < / < 15*k in which s is the total thickness of the laminate.

23. Process according to any of Claims 1 to 9 and 13 to 22 or electrocatalytically active or activatable laminate according to any of Claims 10 to 22, characterized in that the thickness s of the whole laminate is between 40 pm and 100 pm.

24. Process according to any of Claims 1 to 9 and 13 to 23 or electrocatalytically active or activatable laminate according to any of Claims 10 to 23, characterized in that the laminate has a boundary layer free of the electrocatalyst and textile fabric, where the boundary layer has a thickness g, characterized in that the thicknesses are subject to the following relationships:0.01*s < g < 0.4*s in which s is the total thickness of the laminate.202400195 Foreign Filing 3025. Use of a laminate according to any of Claims 10 to 24 as electrocatalytically active or activatable anion exchange membrane.

26. Use according to Claim 25 in a process for producing hydrogen and oxygen by electrolysis of water in an alkaline environment.

27. Electrolyser comprising at least one laminate according to Claims 10 to 24.

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