Bipolar plate for a fuel cell stack or electrolyser stack, and method for production thereof

Abstract

The invention relates to a cell-stack transport layer (130) for an electrochemical cell stack, in particular a fuel cell stack or an electrolysis cell stack, having an anode-side or cathode-side transport layer element (131) for transporting a medium of the cell stack, wherein the transport layer element (131) has a diffusion barrier (140) on its membrane side (134), which can face or faces a membrane (110) of the cell stack.

Description

[0001] Description

[0002] title

[0003] BIPOLAR PLATE FOR A FUEL CELL STACK OR AN ELECTROLYSER STACK, AND METHOD FOR THE PRODUCTION THEREOF

[0004] The invention relates to a cell stack transport layer, a membrane electrode assembly, and a method for producing a cell stack transport layer for an electrochemical cell stack, in particular a fuel cell stack or an electrolysis cell stack. Furthermore, the invention relates to an electrochemical cell stack, an electrochemical assembly, or an electrochemical system.

[0005] State of the art

[0006] In an electrolyzer of an electrolyzer unit (stationary or mobile), e.g., an electrolyzer system, e.g., a fuel cell system, e.g., a fuel cell vehicle, or as an electrolyzer plant, water is electrochemically converted into hydrogen and oxygen using electrical energy, generating heat. - In a low-temperature polymer electrolyte fuel cell of a fuel cell unit (mobile or stationary), e.g., a fuel cell system, e.g., a fuel cell vehicle, two reactants of two operating media are electrochemically converted into electrical energy and heat.

[0007] The electrolyzer unit or fuel cell unit comprises at least one membrane electrode assembly (MEA) with a PEM (proton exchange membrane), an AEM (anion exchange membrane), or a bipolar membrane. Typically, the electrolyzer unit or fuel cell unit is designed with a plurality of membrane electrode units arranged in a stack with bipolar plates arranged between them, the so-called electrolysis cell stack or fuel cell stack (cell stack, stack) with a plurality of individual electrolysis cells or individual fuel cells (individual cells).

[0008] Task

[0009] With increasing operating life, electrolysis cell stacks or fuel cell stacks degrade (hydrogen embrittlement, oxide layer formation, cracks in the cell stack, etc.). - It is an object of the invention to provide an improved electrolysis cell stack or an improved fuel cell stack. In doing so, a constant focus is also on increasing the power density of electrolysis cell stacks or fuel cell stacks and / or, if possible, maintaining it permanently.

[0010] Disclosure of the invention

[0011] The object of the invention is achieved by means of a cell stack transport layer for an electrochemical cell stack; by means of a membrane electrode assembly for an electrochemical cell stack; by a method for producing a cell stack transport layer for an electrochemical cell stack; and by means of an electrochemical cell stack, in particular an electrolysis cell stack or a fuel cell stack; an electrochemical unit, and an electrochemical system. Advantageous developments, additional features, and / or advantages of the invention emerge from the dependent claims and the following description.

[0012] The cell stack transport layer according to the invention comprises an anode-side or cathode-side transport layer for transporting a medium of the cell stack, wherein the transport layer has a diffusion barrier on its membrane side, which is facing or can be directed toward a membrane of the cell stack. Depending on the technology, this can prevent protons, hydrogen, or anions from leaving the membrane, e.g., a membrane-electrode unit, via the cell stack transport layer, e.g., an (L)GDL, PTL, or CTL (see below). This means that diffusion of protons, hydrogen, anions (hydroxide ions), etc., into the actual (L)GDL, PTL, or CTL, etc., is limited or essentially prevented, which leads to an increase in the efficiency of the cell stack.

[0013] The diffusion barrier can be provided essentially cohesively or integrally on the membrane side of the transport layer body. In this case, the diffusion barrier can be provided indirectly, i.e. with the interposition of a further layer, or directly on the membrane side of the transport layer body. The diffusion barrier can be provided essentially over the entire surface of the membrane side or globally in certain regions. A catalytic electrode of the cell stack transport layer can be provided essentially cohesively or integrally on the diffusion barrier. In this case, the catalytic electrode can be provided indirectly, i.e. with the interposition of a further layer, or directly on the membrane-side diffusion barrier of the transport layer body. Furthermore, the catalytic electrode can essentially completely cover the diffusion barrier.

[0014] The transport layer body can be constituted by vacancies and full spaces, at least on its membrane side, with full spaces being formed by the presence of a material of the transport layer body and vacancies (recesses, holes, pores, etc.) by the absence of one. The diffusion barrier can be provided on the membrane side of the transport layer body, preferably away from (cf. Figs. 6 to 9, last illustration in the respective row) the full-space edges delimiting the vacancies, essentially over the entire surface (cf. Fig. 5) of the full spaces.

[0015] Aside from the vacancies, the diffusion barrier can only be provided at / in full spots of the transport layer body. Furthermore, the diffusion barrier can essentially completely cover full spots of the transport layer body. Furthermore, the diffusion barrier can essentially only partially cover full spots of the transport layer body. Material full spot edges of full spots delimiting vacancies can each have one or no substantially completely surrounding diffusion barrier, can be partially or substantially completely free of a previous diffusion barrier, and / or can be constituted solely by a material of the transport layer body. A minimum thickness of the diffusion barrier can be on average approximately: 2nm, 3nm, 5nm, 10nm, 20nm, 30nm, 40nm, 60nm, 80nm, 100nm, 125nm, 150nm, 175nm, 200nm, 250nm, 300nm, 400nm, 500nm, 600nm or 750nm, each possibly ±5-15%.The maximum thickness of the diffusion barrier can be approximately 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 7.5 μm, 5 μm, 2.5 μm, 2 μm, 1.5 μm, 1 μm, 0.75 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.25 μm, 0.2 μm, 0.175 μm, 0.15 μm, or 0.125 μm, each with a possible ±5-15% variation. Accordingly, the thickness of the diffusion barrier can lie between such a minimum and such a maximum thickness, or between two such minimum or two such maximum thicknesses.

[0016] The transport layer body can have a catalytic electrode on its membrane side. The catalytic electrode can be provided essentially in a materially bonded or integral manner on the transport layer body. It is preferred that the catalytic electrode not be provided on the diffusion barrier. Furthermore, the catalytic electrode can be provided on the material edges of full sites that delimit vacancies. And islands of the catalytic electrode can be provided on the transport layer body, spaced apart by the diffusion barrier, in particular on / in a plane.

[0017] The diffusion barrier can be designed such that three-phase boundaries of the cell stack can extend below the full thickness of the transport layer body. The diffusion barrier can be designed as a substantially electrically and / or substantially thermally conductive diffusion barrier. This means, conversely, that the diffusion barrier cannot be designed as an electrical and / or thermal insulator. The cell stack transport layer can be designed as a cell stack transport layer of a membrane-electrode assembly according to the invention.

[0018] The membrane electrode assembly according to the invention comprises a membrane, at least one cell stack transport layer, and a catalytic electrode arranged therebetween. A diffusion barrier is provided between the catalytic electrode and a membrane side of a transport layer body of the cell stack transport layer. The membrane can be formed with at least one catalytic electrode, e.g., as a catalyst-coated membrane. Additionally or alternatively, a catalytic electrode can be provided on at least one transport layer body of the membrane electrode assembly. This means that the membrane electrode assembly comprises at least one cell stack transport layer and a membrane, wherein at least one catalytic electrode of the membrane electrode assembly can be provided on the cell stack transport layer and / or the membrane.

[0019] At least one catalytic electrode can be provided integrally or cohesively on the membrane and / or the cell stack transport layer. The diffusion barrier can be designed such that three-phase boundaries of the cell stack extend below the full thickness of the transport layer body. And the cell stack transport layer of the membrane-electrode assembly can be designed as a cell stack transport layer according to the invention.

[0020] In the method according to the invention, a membrane side of an anode-side or cathode-side transport layer, which can be turned toward a membrane of the cell stack, is coated with a diffusion barrier. The transport layer, ie, within the scope of the method, a blank of the cell stack transport layer to be produced, can be designed as a pre-separated or "endless" (roll) transport layer. In this case, the separated transport layer can have at least one or at least two subsequently desired dimensions. In the first case, the transport layer can have all essential subsequently desired dimensions.

[0021] The membrane side can be coated, for example, by (Plasma Assisted) Physical Vapor Deposition: (PA)-PVD, (Plasma Assisted) (Metalorganic) Chemical Vapor Deposition: (PA)-(MO)-CVD, Atomic Layer Deposition: ALD, Electrodeposition, Electron Beam Evaporation, Thermal Evaporation, Thermal Spraying, Inkprinting, Plasma Spraying, Electrochemical Deposition, Dipping in Bath, etc. The designations in parentheses are applicable extensions of the respective coating process and thus subprocesses of a higher-level process group.In addition to the coating step according to the invention, the manufacturing method can further comprise at least one of the following steps: a) providing the transport layer body, b) establishing voids in the transport layer body, c) cleaning the transport layer body at least on the membrane side, d) applying a mask at least on the membrane side, e) defining full-site edges of the transport layer body away from voids in the membrane side for removing the diffusion barrier, f) removing the diffusion barrier on the full-site edges, g) selectively removing the diffusion barrier, and / or h) removing the material of the mask.

[0022] In step c), surface oxide, if necessary, can be removed at least on the membrane side of the blank. Cleaning can be carried out, for example, in a chemical bath with at least one cleaning medium and / or at least one acid, by ion sputtering, reactive ion etching, etc. If necessary, this can be assisted by ultrasound. In step d), the mask can, for example, contain a photoresist, an imprint resist, etc. Step e) can be carried out, for example, by processes such as optical lithography, imprint lithography, removal by edge rounding, etc. Step f) can be carried out, for example, by ion sputtering, reactive ion etching, chemical removal, and oxide removal in the bath with optional ultrasound, etc.

[0023] Possible processes in step g) are, for example, mechanical removal of material tips, selective ion sputtering or ion etching under an electric field, sputtering or ion etching at a shallow angle, immersing the material tips in an acid bath, etc. (particularly in a process according to Fig.

[0024] 8). Furthermore, the transport layer body can be flushed with a medium that (selectively) removes the material of the diffusion barrier, such as an acid, an abrasive medium, etc. (particularly in a process according to Fig.

[0025] 9). This allows the diffusion barrier to be preferentially removed at the openings of the vacancies on the membrane side of the transport layer body. Removal of the mask in step h) can be achieved, for example, using a developer for photoresist, a solvent for dissolving the mask material, etc.

[0026] A manufacturing method can comprise at least: step a) and the coating step. A manufacturing method can comprise at least: step a), the coating step and steps d), e), f) and h). A manufacturing method can comprise at least: steps a), d), e), the coating step and step h). A manufacturing method can comprise at least: steps a), b), the coating step and step g). A manufacturing method can comprise at least: step a), the coating step and step g). - In this case, step c) can be carried out after step a), after step b) or before step d).

[0027] The manufacturing process can be implemented as a discontinuous manufacturing process or a continuous manufacturing process. A cell stack transport layer strip produced by a continuous manufacturing process can be separated into cell stack transport layers. This can be achieved, for example, by a manufacturing step for creating a component geometry for the cell stack transport layers, e.g., by a final shaping process, such as a punching process, a laser cutting process, etc. The cell stack transport layer of the manufacturing process can be implemented as a cell stack transport layer according to the invention.

[0028] In embodiments, the membrane can be configured, for example, as an exchange membrane, a proton / anion / hydroxide exchange membrane, a proton exchange membrane: PEM (e.g., from Nation™), an anion exchange membrane: AEM, etc. The membrane can be configured as a catalyst-coated membrane with at least one catalytic electrode (catalyst-coated membrane: CCM).

[0029] Furthermore, in embodiments, the catalytic electrode can be provided on the membrane and / or the cell stack transport layer. The catalytic electrode comprises, for example, a pure / alloyed metal and / or metal oxide. In particular, the catalytic electrode comprises at least one platinoid, preferably platinum, iridium, and / or ruthenium. The catalytic electrode can be configured, for example, in the form of a layer, in the form of nanoparticles (optionally with an ionomer, e.g., Nation™), etc.

[0030] Furthermore, in embodiments, the anode-side or cathode-side cell stack transport layer can comprise, for example, a porous material, a microstructure material, etc. Furthermore, the cell stack transport layer can be formed as a (liquid / )gas diffusion layer: (L)GDL, a porous transport layer: PTL, a catalytic cell stack transport layer (Catalytic Transport Layer: CTL, i.e., a cell stack transport layer with a catalytic electrode), etc.

[0031] Furthermore, in embodiments, the diffusion barrier can be formed, for example, as a diffusion barrier layer, a diffusion barrier layer, etc. The diffusion barrier can comprise, for example, a metallic (e.g., tungsten, molybdenum, etc., or an alloy), a non-metallic (e.g., oxide(s), nitride(s), carbide(s), hydride(s), or combination(s) thereof; diamond-like carbon; etc.), and / or an organic material. The material can be (completely) non-polar or exhibit a significant to pronounced (ionic) charge separation within the material.

[0032] In the cell stack, the aggregate, or the system according to the invention, the cell stack or a cell stack of the aggregate or system comprises a plurality of cell stack layers. The cell stack, the aggregate, or the system can comprise a cell stack transport layer and / or a membrane electrode assembly according to the invention. Furthermore, cell stack transport layers of the cell stack, the aggregate, or the system can be produced by a method according to the invention.

[0033] In the cell stack, for example, a plurality of bipolar plates and membrane electrode units (cell stack transport layer, membrane or CCM, cell stack transport layer as a coherent or loose composite) can alternate with one another within the cell stack itself. Furthermore, the unit can be designed as an electrolyzer unit, a CO2 electrolysis unit, a fuel cell unit, etc. Furthermore, the system can be designed as an electrolyzer system, a CO2 electrolysis system, a fuel cell system, etc.

[0034] Short description of the characters

[0035] The invention is explained in more detail below using exemplary embodiments with reference to the attached schematic and not-to-scale drawing. In the invention, a feature can be configured positively, i.e., present, or negatively, i.e., absent. In this specification, a negative feature is not explicitly explained as a feature unless it is important for the invention to be absent. This means that the invention actually made, and not one constructed by the prior art, consists in omitting this feature. The absence of a feature (negative feature) in an exemplary embodiment indicates that the feature may be optional (to a person skilled in the art). - In the merely exemplary figures (Fig.) of the drawing show:

[0036] Fig. 1 shows a simplified block diagram of an embodiment of a fuel cell unit with an electrochemical fuel cell stack for a fuel cell system of a fuel cell vehicle, Fig. 2 shows a simplified block diagram of an embodiment of an electrolyzer unit with an electrochemical electrolysis cell stack for an electrolyzer system, Figs. 3 and 4 show idealized, schematic and centrally sectioned side views of an embodiment of a cell stack transport layer according to the invention of a membrane electrode assembly according to the invention, Figs. 5 to 9 are schematic flow diagrams of five embodiments of methods according to the invention for producing cell stack transport layers for electrochemical cell stacks, and Fig. 10 is a schematic representation of a system for the continuous production of a cell stack transport layer strip or cell stack transport layers according to the invention.

[0037] Embodiments of the invention

[0038] The invention is explained in more detail for an electrochemical cell stack 10, 60 of a fuel cell unit 1 (see Fig. 1) and an electrolyzer unit 51 (see Fig. 2). However, the invention is also applicable to a CCh electrolysis unit, another fuel cell unit 1 and / or another electrolyzer unit 51, etc. (see above). - The drawing shows only those sections of a fuel cell system or an electrolyzer system that are necessary for an understanding of the invention. - Although the invention is described and illustrated in detail by means of preferred embodiments, the invention is not limited by the disclosed embodiments. Other variations can be derived therefrom without departing from the scope of the invention.

[0039] Fig. 1 and 2 each show an electrochemical unit 1, 51 (Fig. 1: fuel cell unit 1, Fig. 2: electrolyzer unit 51) each according to a general embodiment, with at least one, in particular a plurality of to an electrochemical cell stack 10, 60 or a stack

[0040] 10, 60 (Fig. 1 : fuel cell stack 10, Fig. 2: electrolysis cell stack 60) bundled electrochemical single cells 11 , 61 (Fig. 1 : single fuel cells

[0041] 11, Fig. 2: Individual electrolysis cells 61), which are housed in a preferably fluid-tight stacked housing 16, 66. Each individual cell 11, 61 comprises an electrode chamber 12, 62 designed as an anode chamber 12, 62 and an electrode chamber 13, 63 designed as a cathode chamber 13, 63, which are spatially and electrically separated from one another by a membrane, e.g., a membrane-electrode assembly 100.

[0042] A bipolar plate 17, 67 is arranged between two directly adjacent membrane electrode units 100, 100 including a respective anode compartment 12, 62 and a respective cathode compartment 13, 63, which serves, among other things, to supply / discharge media 3 / 4, 5 / 6, 7 / 8; 53 / 54, 56 for an anode compartment 12, 62 of a first individual cell 11, 61 or a cathode compartment 13, 63 of a directly adjacent second individual cell 11, 61 and, moreover, realizes an electrically conductive connection between these individual cells 11, 11; 61, 61. - The cathode compartments 13, 63 and, if applicable, their common inflow area or their actual electrodes form a cathode 39, 89 and the anode compartments 12, 62 and, if applicable, their common inflow area or their actual electrodes form an anode 29, 79 of the cell stack 10, 60.

[0043] In principle, the membrane electrode assemblies 100 of the cell stack 10, 60 can comprise PEMs (proton exchange membranes), AEMs (anion exchange membranes), or bipolar membranes. PEMs are preferred for a fuel cell stack 10, and AEMs or PEMs are preferred for an electrolysis cell stack 60. In addition to the fuel cell unit 1 or the electrolyzer unit 51, the fuel cell system or electrolyzer system comprises peripheral system components, such as a control unit, which can be one of the fuel cell vehicle or the electrolyzer system itself, etc.

[0044] The following explanations relate only to the electrochemical unit as a fuel cell unit 1, for example, according to Fig. 1. - To supply the electrochemical cell stack 10 as a fuel cell stack 10 with its actual operating media 3 (anode operating medium, actual fuel), 5 (cathode operating medium, usually air), the fuel cell unit 1 has an anode supply 20 and a cathode supply 30.

[0045] The anode supply 20 comprises in particular: a fuel reservoir 23 for the anode operating medium 3 (flowing in); an anode supply path 21 (medium path 21) with a pressure reducer, a shut-off valve and / or a metering valve 27 (for example), as well as a jet pump 24 (jet pump 24, ejector 24); an anode exhaust gas path 22 (medium path 22) for an anode exhaust gas medium 4 (flowing out, usually into the environment 2); a fuel recirculation path 25 with a fluid conveying device 26 located therein; optionally a water separator with preferably a water tank.

[0046] The cathode supply 30 comprises in particular: a cathode supply path 31 (medium path 31) for the cathode operating medium 5 (flowing in, usually from the environment 2), with a fluid conveying device 33; a cathode exhaust gas path 32 (medium path 32) for a cathode exhaust gas medium 6 (flowing out, usually into the environment 2), preferably with a turbine 34, in particular for the fluid conveying device 33; a humidity exchanger 36, in particular a gas-to-gas humidifier 36; optionally a cathode-side stack bypass 35 (wastegate 35) between the cathode supply path 31 and the cathode exhaust gas path 32, with a bypass valve 37; optionally a water separator, preferably with a water tank.

[0047] The fuel cell unit 1 further comprises, in particular, a cooling medium supply 40 of a thermal system, in particular of the fuel cell vehicle, through which the fuel cell stack 10 can be integrated into a cooling circuit for temperature control, preferably by means of its bipolar plates 17 (cooling medium paths 43). The cooling medium supply 40 comprises a cooling medium inlet path 41 and a cooling medium outlet path 42. The cooling medium 7 (inflowing), 8 (outflowing) circulating in the cooling medium supply 40 is preferably conveyed by means of at least one cooling medium conveying device 44.

[0048] The following explanations relate only to the electrochemical unit as electrolyzer unit 51, e.g., according to Fig. 2. - To supply the electrochemical cell stack 60 as electrolysis cell stack 60 with water 53 as a supply medium 53, the electrolyzer unit 51 has a water supply 70. Water 53 can also be understood as a basic aqueous electrolyte 53. And to remove the media 54, 56 from the cell stack 60, the electrolyzer unit 51 has a media removal 80.

[0049] The water supply 70 comprises in particular: a water reservoir 73 for the water 53 (flowing in), a supply path 71 (medium path 71) and a water conveying device 76 on / in the supply path 71. - The media withdrawal 80 has at least one disposal path 81 (medium path 81) for (cooling) water 54 or (cooling) water with oxygen 54 back into the water reservoir 73, optionally with a gas separator for oxygen, and / or in another direction (shown in dashed lines), e.g. into the environment 2.

[0050] A product medium 56 of the electrolyzer unit 51, i.e., the produced hydrogen 56, is transported away through a product medium path 82 of the medium removal 80. A water separator 83 with a valve 84 can be inserted into the product medium path 82 to separate water in the product medium path 82. The water separated in the water separator 83 can be conveyed back into the water reservoir 73 or in another direction, e.g., into the environment 2, possibly by gravity. The produced hydrogen 56 can be stored, for example, in a hydrogen storage unit 90, wherein the product medium path 82 can flow directly into the hydrogen storage unit 90. Another method of transporting the hydrogen 56 away is, of course, possible.

[0051] Depending on the embodiment of the electrolyzer unit 51, a media guide in the cell stack 60 can be designed differently. In this case, it is possible to provide a temperature control system that differs from an electrochemical function of the cell stack 60, in particular water cooling, or to implement the temperature control system together with the electrochemical function of the cell stack 60.

[0052] In particular, it is possible, in membrane electrode assemblies 100 with AEMs, to set up a supply of water 53, possibly exclusively on the anode side (dotted arrow at the anode 79). In this case, the water 53 can flow directly into the "anode" 79. Furthermore, it is possible, in membrane electrode assemblies 100 with PEMs, to set up a supply of water 53, possibly exclusively on the cathode side 89 (dotted arrow at the cathode 89). In this case, the water 53 can flow directly into the "cathode" 89.

[0053] Now further with reference to Figs. 3 and 4. - For the forward / return transport of a medium 3, 4; 5, 6 of the cell stack 10, 60 to / from a respective catalytic electrode 120 in an anode compartment 12, 62 or in a cathode compartment 13, 63, a cell stack transport layer 130 is arranged in the respective anode compartment 12, 62 or cathode compartment 13, 63. For the design of the catalytic electrode 120, see further above, and / or for the design of the cell stack transport layer 130, see also above.

[0054] The cell stack transport layer 130 is geometrically, i.e., in terms of its dimensions, essentially formed by a transport layer body 131. The transport layer body 131 is constituted in the present case by vacancies 132 and full spaces 133, wherein a vacancy 132 is characterized by the absence of a material of the transport layer body 131 and a full space 133 is characterized by the presence of a material of the transport layer body 131. The vacancies 132 can be formed as recesses, holes, pores, etc. For the design of the transport layer body 131, see also above.

[0055] At least one cell stack transport layer 130 can be an integral part of a membrane electrode assembly 100. Preferably, a membrane electrode assembly 100 has a cell stack transport layer 130 on each of its two large-area sides, one on the anode side and one on the cathode side. A mixed form, i.e., a membrane electrode assembly 100 with a single, permanently installed anode- or cathode-side cell stack transport layer 130 and a separate cathode- or anode-side cell stack transport layer 130 for the same individual cell 11, 61, is of course applicable. Alternatively, the cell stack transport layers 130 of the same individual cell 11, 61 can also be provided separately from a membrane electrode assembly 100, i.e., not in a composite.

[0056] The anode-side or cathode-side transport layer body 131 has a diffusion barrier 140 on its membrane side 134 or the membrane side 134 of the cell stack transport layer 130, respectively. The membrane side 134 faces a membrane 110 of the cell stack 10, 60 or, within a membrane electrode unit 100 and also within the cell stack 10, 60, faces a respective membrane 110. For the design of the diffusion barrier 140 and / or the design of the membrane 110, see also above.

[0057] The catalytic electrode 120 can be provided on the anode side and / or the cathode side, either on the membrane 110 or on the diffusion barrier 140. In the first case, the membrane 110 can be designed as a CCM 110, 120 with at least one catalytic electrode 120 on at least one of its two large-area sides. Preferably, a CCM 110, 120 has the membrane 110 and two catalytic electrodes 120 on its two large-area sides. It is preferred that only a single catalytic electrode 120 be provided on the anode side and the cathode side, either on the membrane 110 or on the diffusion barrier 140.

[0058] On the membrane side 134, the diffusion barrier 140 does not substantially cover the empty spaces 132 of the transport layer body 131. This means that sections of the diffusion barrier 140 essentially do not extend into spaces defined by the walls of the empty spaces 132 of the transport layer body 131 and the membrane 110 or the respective catalytic electrode 120 (see Fig. 4). - On the membrane side 134, the diffusion barrier 140, or sections of the diffusion barrier 140, are located on the full spaces 133 of the transport layer body 131. Here, on the membrane side 134, sections of the diffusion barrier 140 can essentially completely cover the full spaces 133 (see Figs. 3 and 4, far right). This can essentially affect all full spots 133 on the membrane side 134. - Furthermore, sections of the diffusion barrier 140 can have full spots 133 in a respective central region on the membrane side 134, essentially over their entire surface (cf. Fig.3 and 4 (center and left) and at their 'radial' outer edges located in / on the membrane side 134, the full-site edges, are essentially not covered. This can affect essentially all full sites 133 on the membrane side 134. In one embodiment, these full-site edges free of the diffusion barrier 140 can be coated with the catalytic electrode 120.

[0059] An embodiment of a method 200, 300, 400, 500, 600 for producing, for example, a cell stack transport layer 130 as described above is explained in more detail below with reference to Figs. 5 to 9. In the manufacturing method 200, 300, 400, 500, 600, a diffusion barrier 140 is provided on a membrane side 134 of an anode-side or cathode-side transport layer body 131, ie, its membrane side 134 is coated with the diffusion barrier 140 (coating step, no reference symbol; Fig. 5 right, Fig. 6 top right, Fig. 7 bottom center, Fig. 8 bottom right, Fig. 9 right of center). By these manufacturing processes 200, 300, 400, 500, 600, cell stack transport layers 130 and / or cell stack transport layer tapes (cf. Fig. 10) can be obtained.

[0060] A manufacturing method 200, 300, 400, 500, 600 comprises, in addition to the coating step, one or a plurality of the following, not necessarily chronologically ordered, steps a) to h): a) providing the transport layer body 131, b) establishing voids 132 in the transport layer body 131, c) cleaning the transport layer body 131 at least on the membrane side 134, d) applying a mask 150 at least on the membrane side 134, e) defining full-site edges of the transport layer body 131 away from voids 132 in the membrane side 134 for removing the diffusion barrier 140, f) removing the diffusion barrier 140 on the full-site edges, g) selectively removing the diffusion barrier 140 and / or h) removing the material the mask 150. - For the details of the individual steps a) to h) see also above.

[0061] For all manufacturing processes 200, 300, 400, 500, and 600, step a) is mandatory and step c) is optional (therefore bracketed in Figs. 5 to 9), whereby step c) can be applied before / after step a), after step b), or before step d). Transport layer body 131 can be configured as an individual transport layer body 131 or as an "endless" transport layer body 131 (cf. Fig. 10, roll for a cell stack transport layer belt). In manufacturing processes 200, 300, 400, and 600, transport layer body 131 already has its empty spaces 132, whereas in manufacturing process 500, the empty spaces 132 must first be introduced into transport layer body 131 (cf. below).

[0062] The manufacturing method 200 according to Fig. 5 comprises, in chronological order, at least: step a), preferably step c), and the coating step. This results in a full-surface diffusion barrier 140 on the full areas 133 of the membrane side 134; ie, the full areas 133, including their full-surface edges, are essentially coated over their entire surface.

[0063] The manufacturing method 300 according to Fig. 6 comprises, in chronological order, at least: step a), the coating step, and steps d), e), f), and h). A mask 150 is applied after the coating step (step d)), then solid edges (and / or other edges) are defined for removing the diffusion barrier 140 on the solid edges (step e)), then the diffusion barrier 140 is removed only in the area defined by the solid edges (and / or other edges) (step f)), and finally, the remaining material of the mask is removed (step h)). This results in a diffusion barrier 140 on the solid edges 133 of the membrane side 134 that is missing in the area of ​​the solid edges (and / or the other edges), but otherwise essentially (full-)surface.

[0064] The manufacturing method 400 according to Fig. 7 comprises, in chronological order, at least: steps a), d), e), the coating step, and step h). Temporarily after applying a mask 150 (step d), solid edges (and / or other edges) are defined for removing the diffusion barrier 140 on the solid edges (step e). For this purpose, the mask 150 is left only in the region of the solid edges (and / or the other edges) and removed in the majority of the intermediate regions. The coating step then follows, and subsequently, the remaining material of the mask is removed (step h). This again results in a diffusion barrier 140 on the solid edges 133 of the membrane side 134 that is missing in the region of the solid edges (and / or the other edges), but otherwise essentially (full-)surface.

[0065] The manufacturing method 500 according to Fig. 8 comprises, in chronological order, at least: steps a), b), preferably step c), the coating step, and step g). Temporarily after the provision of the transport layer body 131 (or a blank of a transport layer body 131, step a)), which has no voids 132, voids 132 are created in the transport layer body 131 (step b)). In this case, elevations on the future membrane side 134 are specifically created by a material of the transport layer body 131 at the outer openings of the voids 132 in the thickness direction of the transport layer body 131. The transport layer body 131 can then be cleaned (step c)) and coated with the diffusion barrier 140. Subsequently, the diffusion barrier 140 is selectively removed from the raised regions of the transport layer body 131 (step g), see above.This results in a diffusion barrier 140 on the full spots 133 of the membrane side 134 which is missing in the area of ​​the full spots edges (and / or the other edges), but otherwise essentially (full-)surface.

[0066] And the manufacturing method 600 according to Fig. 9 comprises, in chronological order, at least: step a), preferably step c), the coating step, and step g). Here, after the coating step, the transport layer body 131 is rinsed or flushed, for example, with a medium that selectively removes the material of the diffusion barrier 140 (step g), see above). This results in a diffusion barrier 140 on the full areas 133 of the membrane side 134 that is missing in the area of ​​full area edges (and / or other edges), but otherwise essentially (full-)area. The manufacturing methods 200, 300, 400, 500 show applications to transport layer bodies 131, in which the empty areas 132 (e.g. recesses, holes; e.g. lasered) were introduced after their shaping as blanks (i.e. before step a)).Alternatively, the manufacturing method 600 shows an application to a transport layer body 131, which already has the voids 132 (e.g., pores) due to its original shaping, possibly as a blank. It is of course possible to apply the manufacturing methods 200, 300, 400, 500 to a transport layer body 131 according to the manufacturing method 600, and the manufacturing method 600 to a transport layer body 131 according to the manufacturing methods 200, 300, 400, 500.

[0067] Fig. 10 schematically shows an application of the invention to a continuous production process for anode-side or cathode-side cell stack transport layers 130 using a cell stack transport layer belt. The cell stack transport layer belt can be designed as a roll with pre-structured (vacancies 132) or porous (vacancies 132) starting material for the transport layer bodies 131 to be produced (e.g., for production methods 200, 300, 400, 600). It is of course possible to introduce the vacancies 132 into the cell stack transport layer belt only during the production process (e.g., for production method 500).

[0068] From this cell stack transport layer strip, the cell stack transport layers 130 (see above) are produced using a manufacturing process, for example, one of the aforementioned manufacturing processes 200, 300, 400, 500, 600. Depending on the manufacturing process 200, 300, 400, 500, 600 used, the respective selection of steps b) to h) can be carried out in a single large (dashed box) or several separate chambers of a system for processing the cell stack transport layer strip or for producing the cell stack transport layers 130.

[0069] After the last step of the applied manufacturing process 200, 300, 400, 500, 600, the cell stack transport layer strip can be separated into anode-side or cathode-side cell stack transport layers 130. Depending on the system and the cell stack transport layer strip, the resulting cell stack transport layers 130 can receive their final shape through a shaping process, e.g., through a punching process and / or a laser cutting process, etc. - It is of course possible to use a discontinuous process to produce the cell stack transport layers 130.

Claims

Claims 1. Cell stack transport layer (130) for an electrochemical cell stack (10, 60), in particular a fuel cell stack (10) or an electrolysis cell stack (60), with an anode-side or cathode-side transport layer body (131) for transporting a medium (3, 4; 5, 6) of the cell stack (10, 60), characterized in that the transport layer body (131) has a diffusion barrier (140) on its membrane side (134), which can be turned or faces a membrane (110) of the cell stack (10, 60).

2. Cell stack transport layer (130) according to the preceding claim, characterized in that: • the diffusion barrier (140) is provided on the membrane side (134) of the transport layer body (131) essentially in a material-locking or integral manner, • the diffusion barrier (140) on the membrane side (134) is provided globally essentially over the entire surface or globally in certain areas, and / or • a catalytic electrode (120) of the cell stack transport layer (130) is provided on the diffusion barrier (140) in a substantially cohesive or integral manner.

3. Cell stack transport layer (130) according to one of the preceding claims, characterized in that the transport layer body (131) is constituted at least on its membrane side (134) by vacancies (132) and full spots (133), wherein full spots (133) are formed by a presence and vacancies (132) by an absence of a material of the transport layer body (131), and in particular the diffusion barrier (140) on the membrane side (134) of the transport layer body (131) is preferably provided away from the full-space edges delimiting the empty spaces (132) essentially over the entire surface of the full spaces (133).

4. Cell stack transport layer (130) according to one of the preceding claims, characterized in that: • the diffusion barrier (140) is provided apart from the empty spaces (132) only at / in full spaces (133) of the transport layer body (131), • the diffusion barrier (140) essentially completely covers full areas (133) of the transport layer body (131), and / or • the diffusion barrier (140) essentially only partially covers full areas (133) of the transport layer body (131).

5. Cell stack transport layer (130) according to one of the preceding claims, characterized in that empty spaces (132) delimiting, material full positions of full positions (133): • each have one or no substantially completely circumferential diffusion barrier (140), • are partially or substantially completely freed from a previous diffusion barrier (140), and / or • are constituted only by a material of the transport layer body (131).

6. Cell stack transport layer (130) according to one of the preceding claims, characterized in that a minimum thickness of the diffusion barrier (140) on average is approximately: 2 nm, 3 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 60 nm, 80 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 250 nm, 300 nm, 400 nm, 500 nm, 600 nm or 750 nm, each optionally ±5-15%, and / or a maximum thickness of the diffusion barrier (140) on average is approximately: 50 pm, 40 pm, 30 pm, 20 pm, 10 pm, 7.5 pm, 5pm, 2.5pm, 2pm, 1.5pm, 1 pm, 0.75pm, 0.6pm, 0.5pm, 0.4pm, 0.3pm, 0.25pm, 0.2pm, 0.175pm, 0.15pm or 0.125pm, each with an error of ±5-15%.

7. Cell stack transport layer (130) according to one of the preceding claims, characterized in that the transport layer body (131) has a catalytic electrode (120) on its membrane side (134), and: • the catalytic electrode (120) is provided essentially in a material-locking or integral manner on the transport layer body (131), • the catalytic electrode (120) is provided on material full-site edges of full sites (133) that delimit empty sites (132), and / or • Islands of the catalytic electrode (120) are provided on the transport layer body (131) in particular spaced apart on / in a plane by the diffusion barrier (140).

8. Cell stack transport layer (130) according to one of the preceding claims, characterized in that: • the diffusion barrier (140) is designed such that three-phase boundaries (102) of the cell stack (10, 60) can extend below full points (133) of the transport layer body (131), • the diffusion barrier (140) is designed as a substantially electrically and / or substantially thermally conductive diffusion barrier (140).

9. Membrane electrode unit (100) for an electrochemical cell stack (10, 60), in particular a fuel cell stack (10) or an electrolysis cell stack (60), with a membrane (110), at least one cell stack transport layer (130) and a catalytic electrode (120) arranged therebetween, characterized in that a diffusion barrier (140) is provided between the catalytic electrode (120) and a membrane side (134) of a transport layer body (131) of the cell stack transport layer (130).

10. Membrane electrode assembly (100) according to the preceding claim, characterized in that: • at least one catalytic electrode (120) is provided integrally or cohesively on the membrane (110) and / or the cell stack transport layer (130), • the diffusion barrier (140) is designed such that three-phase boundaries (102) of the cell stack (10, 60) extend below full points (133) of the transport layer body (131), and / or • the cell stack transport layer (130) of the membrane electrode assembly (100) is formed according to one of the preceding claims.

11. Method (200 / 300 / 400 / 500 / 600) for producing a cell stack transport layer (130) for an electrochemical cell stack (10, 60), in particular an electrolysis cell stack (60) or a fuel cell stack (10), characterized in that a membrane side (134) of an anode-side or cathode-side transport layer body (131), which can be turned towards a membrane (110) of the cell stack (10, 60), is coated with a diffusion barrier (140).

12. Manufacturing method (200 / 300 / 400 / 500 / 600) according to one of the preceding claims, characterized in that the manufacturing method (200 / 300 / 400 / 500 / 600) can further comprise, in addition to the coating step, at least one of the following steps a) to h): a) providing the transport layer body (131), b) establishing voids (132) in the transport layer body (131), c) cleaning the transport layer body (131) at least on the membrane side (134), d) applying a mask (150) at least on the membrane side (134), e) defining full-site edges of the transport layer body (131) away from voids (132) in the membrane side (134) for removing the diffusion barrier (140), f) removing the diffusion barrier (140) on the full-site edges, g) selectively removing the diffusion barrier (140), and / or h) removing the material of the mask (150).

13. Manufacturing process (200 / 300 / 400 / 500 / 600) according to the preceding claim, characterized in that: • the manufacturing process (200) comprises at least: step a) and the coating step in the following chronological order, • the manufacturing method (300) comprises in the following chronological order at least: step a), the coating step and steps d), e), f) and h), • the manufacturing method (400) comprises at least: steps a), d), e), the coating step and step h) in the following chronological order, • the manufacturing method (500) comprises at least: steps a), b), the coating step and step g) in the following chronological order, or • the manufacturing method (600) comprises, in the following chronological order, at least: step a), the coating step and step g); wherein Step c) can be set up at any time: after step a), after step b) or before step d).

14. Manufacturing method (200 / 300 / 400 / 500 / 600) according to one of the preceding claims, characterized in that: • the manufacturing process (200 / 300 / 400 / 500 / 600) is designed as a discontinuous manufacturing process (200 / 300 / 400 / 500 / 600) or a continuous manufacturing process (200 / 300 / 400 / 500 / 600), • after a cell stack transport layer band produced by a continuous manufacturing process (200 / 300 / 400 / 500 / 600) is separated into cell stack transport layers (130), and / or • the cell stack transport layer (130) is formed according to one of the preceding claims.

15. Electrochemical cell stack (10, 60), electrochemical aggregate (1, 51) or electrochemical system, wherein the cell stack (10, 60), or a cell stack (10, 60) of the aggregate (1, 51) or the system comprises a plurality of cell stack layers (17, 100; 67, 100), characterized in that the cell stack (10, 60), the aggregate (1, 51) or the system comprises a cell stack transport layer (130) and / or a membrane electrode unit (100) according to one of the preceding claims, and / or cell stack transport layers (130) of the cell stack (10, 60), the aggregate- gats (1, 51) or the system are manufactured by a method according to one of the preceding claims.

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