Fuel gas electrode for electrochemical cell

Abstract

The present invention relates to a fuel gas electrode (20) assignable to an electrochemical cell, in particular an electrolysis cell (14), for example a cathode-supported electrolysis cell, or assignable to a fuel cell (12), for example an anode-supported fuel cell, comprising at least one reinforcing element (30) assignable to the fuel gas electrode (20), in particular wholly or partially introducible into the fuel gas electrode (20) and stabilizing the fuel gas electrode (20), in particular a substrate or support region (22), for example a coarse-porous substrate or support region, of the fuel gas electrode (20).

Description

[0001] R.415381

[0002] - 1 -

[0003] Description

[0004] title

[0005] Fuel gas electrode for electrochemical cell

[0006] The present invention relates to the technical field of electrochemical cells, in particular electrolysis cells (SOECs = Solid Oxide Electrolysis Cells = Solid Oxide Electrolysis Cells = Solid Oxide Electrolyzer Cells) or fuel cells (SOFCs = Solid Oxide Fuel Cells = Solid Oxide Fuel Cells), and in particular the technical field of the fuel gas electrodes of such electrochemical cells, arranged, for example, on the fuel gas side, such as on the hydrogen side or Fh side, which can be arranged in series in the form of at least one stack.

[0007] State of the art

[0008] There are different technical approaches to producing hydrogen from water by electrolysis under the supply of electricity, including the S[olid]O[xide]E[lectrolysis]C[ell] technology based on electrochemical cells, especially electrolysis cells.

[0009] Regarding the cell design of SOECs, various concepts exist to ensure the required mechanical stability over their lifetime and to guarantee manufacturability. These concepts are distinguished by their support structure: metal-supported (MSC), electrolyte-supported (ESC), or cathode-supported (CSC). See, for example, Mendonga, C.; Ferreira, A.; Santos, DMF: Towards the Commercialization of Solid Oxide Fuel Cells: Recent Advances in Materials and Integration Strategies. Fuels 2021, 2, 393-419. https: / / doi.org / 10.3390 / fuels2040023

[0010] Due to its open-pore cathode support structure, the CSC is fundamentally very well suited for electrolysis applications requiring high mass conversion. R.415381

[0011] - 2 -

[0012] suitable; however, due to the open-pore cathode support structure, the CSC concept has an intrinsic disadvantage of lower robustness against redox and thermo cycles compared to the other concepts (MSC, ESC); for example, redox cycles lead to an expansion of the material within the cathode, for example in the Ni phase by up to forty percent.

[0013] Analogous or comparable problems arise conceptually with anode-supported support structures (= A[node-]S[upported]C[ell] = ASC), especially with anodes for fuel cells (SOFCs = Solid Oxide Fuel Cells).

[0014] Disclosure of the invention

[0015] Based on the disadvantages and shortcomings outlined above, and taking into account the prior art described above, the present invention aims to further develop a fuel gas electrode of the type mentioned at the outset in such a way as to overcome the aforementioned disadvantages and shortcomings; in particular, the mechanical stability of fuel gas electrodes of electrochemical cells is to be improved.

[0016] This problem is solved by the features of claim 1. Advantageous embodiments of the present invention are described in the dependent claims.

[0017] The present invention proposes an improved and / or reinforced design of the fuel gas electrode substrate or fuel gas electrode support structure for an electrochemical cell, in particular for an electrolysis cell or for a fuel cell, in order to increase the robustness of the electrochemical cell or SOEC against redox and thermo cycles.

[0018] According to the present invention, at least one fuel gas electrode reinforcing component or fuel gas electrode reinforcing element, in particular at least one, for example inert, ceramic mesh or honeycomb structure, or at least one, for example metallic, reinforcing structure, is arranged in the fuel gas electrode, in particular on the fuel gas side, for example hydrogen side or H2 side, as a stability-enhancing structure.

[0019] - 3 -

[0020] at least in part of the fuel gas electrode, which is arranged particularly on the fuel gas side, for example on the hydrogen side or Fh side, as a mechanical support or as mechanical assistance.

[0021] This structure, introduced into at least a part or area or section of the fuel gas electrode, stabilizes the fuel gas electrode, i.e. the SOEC cathode or the SOFC anode, against mechanical failure.

[0022] At the same time, the reinforcing structural element reduces the change in the total volume of the fuel gas electrode in the event of a redox reaction by substituting fuel gas electrode material, thus reducing the risk of cracking and increasing the service life.

[0023] According to a preferred embodiment of the present invention, the fuel gas electrode can

[0024] - as a composition or mixture of nickel (Ni) and gadolinium-doped cerium oxide (GDC) or

[0025] - as a composition or mixture of nickel (Ni) and yttrium-stabilized zirconium dioxide (YSZ) or

[0026] - as an alternative composition or mixture

[0027] be educated.

[0028] Advantageously, these technical effects, in particular the mechanically reinforcing effect, can be achieved within the combustion gas electrode by means of the following exemplary embodiments, which can be provided independently of one another or in any combination with one another:

[0029] - The reinforcing structural element, which has high mechanical stability and temperature resistance and is inert to the gas mixture, can be designed as at least one ceramic plate with holes, as at least one mesh, web or honeycomb structure or as at least one metal sheet or mesh, in particular with a thickness of about 100 micrometers to about 400 micrometers, preferably with a thickness of about 150 micrometers to about 250 micrometers.

[0030] - The reinforcing building or structural element, functioning as a reinforcement element, can have different mesh or hole geometries, such as round, polygonal, oblong, hollow cylindrical and / or oval. R.415381

[0031] - 4 -

[0032] - In addition to net, bridge, honeycomb, mesh or hole geometries, coarse-pored structures are also possible, for example in the range of more than fifty percent and / or with a large pore diameter.

[0033] - The size of the mesh or the diameter of the hole can, in principle, be designed arbitrarily, preferably in the range of about 50 micrometers to about 500 micrometers.

[0034] - The size of the mesh or the diameter of the hole can vary spatially, for example, it may be different in the central area of ​​the electrochemical cell than in the outer areas of the electrochemical cell.

[0035] - The width of the web and / or the distance between the meshes or holes can vary spatially, preferably depending on the mechanical requirements, but especially narrow with little material usage.

[0036] - The reinforcing structural element may be provided with one or more protective layers to prevent a reaction with the fuel gas electrode.

[0037] - The reinforcing structural element can be provided with one or more coatings to increase electrical and / or electronic conductivity.

[0038] - The material in the holes of the reinforcing building or structural element acting as a reinforcing element can have the highest possible porosity, but does not have to be the same material or have the same ratio of materials used as the fuel gas electrode substrate or the fuel gas electrode support structure and / or the fuel gas electrode active layer or the fuel gas electrode active area.

[0039] - The reinforcing structural element can be wholly or partially incorporated into the fuel gas electrode as mechanical support or reinforcement; however, the holes may also be only slightly or not at all filled with fuel gas electrode material. R.415381

[0040] - 5 -

[0041] - If the holes of the reinforcing building or structural element acting as a reinforcing element are filled with fuel gas electrode material, this ensures a good connection to the fuel gas electrode.

[0042] As a further alternative or supplementary embodiment, it is possible to combine the, in particular complete or partial, insertion of the at least one reinforcing element attributable to the fuel gas electrode, in particular the at least one stabilizing or reinforcing structure, into the fuel gas electrode, in particular into the substrate or support region of the fuel gas electrode, with a perforation of the fuel gas electrode, in particular the substrate or support region of the fuel gas electrode, which can be achieved by means of at least one gas (transport) path, in order to improve not only the mechanical stability of the electrochemical cell, but also its mass transport. Here, the respective mesh or hole provided in the reinforcing element can be designed as the respective gas path, in particular as the respective gas transport path, for example as the respective fuel gas transport path.

[0043] The present invention further relates to a method for producing a fuel gas electrode of the type described above, in whose meshes or holes the filling material is printed wholly or partially.

[0044] There are fundamentally different approaches possible for manufacturing the reinforced fuel gas electrode structure. According to the invention, these approaches have in common that the filling compound or filling material for the meshes or holes provided in the reinforcing element is printed directly onto the reinforcing element, in particular into the meshes or holes of the reinforcing element, for example according to the following variants:

[0045] - Pressure of the filling compound or filler material for the meshes or holes of the reinforcing building or structural element acting as a reinforcing element directly onto the reinforcing element,

[0046] then pressure of the fuel gas electrode, in particular the active and / or functional layer of the fuel gas electrode, of all further layers directly onto the composite;

[0047] - Pressure of the filling compound or filler material for the meshes or holes of the reinforcing building or structural element acting as a reinforcing element directly onto the reinforcing element, R.415381

[0048] - 6 -

[0049] Printing of all further layers onto a transfer substrate, for example onto a polymer film, with subsequent relamination of the layer composite onto the fuel gas electrode substrate or the support structure of the fuel gas electrode;

[0050] - Pressure of the filling mass or filling material into the meshes or holes of the reinforcing building or structural element acting as a reinforcing element and pressure of the fuel gas electrode substrate or the support structure of the fuel gas electrode in a single pressure process, in particular realized by utilizing a viscoelastic effect of the fuel gas electrode paste.

[0051] The reinforcing structural element can be designed and / or manufactured as a composite of at least two different components, for example metal and ceramic, in particular with subsequent removal / etching of at least one component, for example to provide a targeted porosity of the reinforcing element.

[0052] If the fuel gas electrode substrate or the support structure is a ceramic component, the sintering process for the support element can be carried out either beforehand or in a co-firing process in one step with the sintering of the fuel gas electrode and, if necessary, further layers.

[0053] The present invention further relates to an electrochemical cell, in particular an electrolysis cell or fuel cell, comprising at least one fuel gas electrode, in particular produced according to the method described above, of the type described above.

[0054] The present invention further relates to an electrolysis cell device for obtaining fuel, in particular hydrogen, from electric current and at least one base material, in particular water, comprising at least one electrochemical cell designed as an electrolysis cell according to the type described above.

[0055] Finally, the present invention relates to a fuel cell device for generating electricity from a fuel, in particular from hydrogen and / or from natural gas, and air, comprising at least one electrochemical cell designed as a fuel cell according to Art.R.415381 set out above.

[0056] - 7 -

[0057] As discussed above, there are various ways to advantageously develop and further refine the teaching of the present invention. For this purpose, reference is made, on the one hand, to the claims subordinate to claim 1 and claim 6; on the other hand, further embodiments, features, and advantages of the present invention are explained in more detail below, inter alia, with reference to the exemplary embodiments illustrated by Figures 2 to 8.

[0058] They show:

[0059] Fig. 1 in schematic cross-sectional representation shows a prior art example of the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell);

[0060] Fig. 2 shows a schematic cross-sectional representation of a first embodiment for the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell), in which the method according to the present invention can be applied and / or used;

[0061] Fig. 3 shows a schematic cross-sectional representation of a second embodiment for the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell), in which the method according to the present invention can be applied and / or used;

[0062] Fig. 4 shows a schematic cross-sectional view of a third embodiment for the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell), in which the method according to the present invention can be applied and / or used; R.415381

[0063] - 8 -

[0064] Fig. 5 shows a schematic cross-sectional representation of a fourth embodiment for the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell), in which the method according to the present invention can be applied and / or used;

[0065] Fig. 6 shows a schematic cross-sectional representation of a fifth embodiment for the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or fuel cell (SOFC = Solid Oxide Fuel Cell), in which the method according to the present invention can be applied and / or used;

[0066] Fig. 7 schematically shows an embodiment of an electrolysis cell device with an electrochemical cell according to the present invention; and

[0067] Fig. 8 shows a schematic representation of an embodiment of a fuel cell device with an electrochemical cell according to the present invention.

[0068] Identical, similar, or corresponding designs, elements, and / or features are identified by the same reference numerals in Figures 1 to 8; a repeated description of these designs, elements, and / or features is omitted. Figures 1 to 8 are not necessarily to scale. Any design and / or dimensioning information in Figures 1 to 8 is purely exemplary.

[0069] With the exception of Fig. 1, which shows a prior art example of the layer structure of an electrochemical cell, in particular an electrolysis cell (SOEC = Solid Oxide Electrolysis Cell) or a fuel cell (SOFC = Solid Oxide Fuel Cell), the respective layer structure of each of the five embodiments according to the invention (see first embodiment according to Fig. 2, second embodiment according to Fig. 3, third embodiment according to Fig. 4, fourth embodiment according to Fig. 5 and fifth embodiment according to Fig. 6)R.415381

[0070] - 9 -

[0071] Each has a fuel gas electrode 20 arranged on the fuel gas side, namely on the hydrogen side or on the Fh side, i.e., a SOEC cathode or a SOFC anode, with a reinforced fuel gas electrode structure;

[0072] Reference numeral 80 denotes an air electrode, i.e., an SOEC anode or an SOFC cathode, here each formed in two layers as a passive air electrode layer 82 and an active and / or functional air electrode layer 84; reference numeral 60 denotes the electrolyte, optionally provided with at least one protective layer; the electrolyte 60 lies between the active and / or functional, finely porous layer 24 of the fuel gas electrode 20 and the active and / or functional layer 84 of the air electrode 80.

[0073] In the respective layer stack according to Fig. 1 to Fig. 6, further layers may be arranged, such as in particular at least one passive or nearly passive or substantially passive air electrode layer, for example at least one passive or nearly passive or substantially passive cathode layer, with the same or similar composition as the electrode arranged between active and / or functional layer 24 and electrolyte layer 60, but with lower porosity for better processability of the electrolyte 60 on the electrode (medium to high or fine porosity).

[0074] Each of the layers shown in Fig. 1 to Fig. 6 can also be designed as a layer composite, regardless of whether the other layers shown in Fig. 1 to Fig. 6 are also designed as a layer composite.

[0075] The fuel gas electrode 20 is

[0076] - as a composition or mixture of nickel (Ni) and gadolinium-doped cerium oxide (GDC) or

[0077] - as a composition or mixture of nickel (Ni) and yttrium-stabilized zirconium dioxide (YSZ) or

[0078] - as an alternative composition or mixture

[0079] trained.

[0080] In order to provide a reinforced fuel gas electrode structure according to the invention, a component associated with the fuel gas electrode 20, namely

[0081] - complete (see first embodiment according to Fig. 2, second embodiment according to Fig. 3 and third embodiment according to Fig. 4) or R.415381

[0082] - 10 -

[0083] - at least partially (see fourth embodiment according to Fig. 5 and fifth embodiment according to Fig. 6)

[0084] A reinforcing element 30 is provided in the fuel gas electrode 20 as a mechanical support or as a mechanical aid, by which the fuel gas electrode 20, and in particular the coarse-porous substrate or support area 22 of the fuel gas electrode 20, is stabilized.

[0085] The respective fuel gas electrode 20 (see first embodiment according to Fig. 2, second embodiment according to Fig. 3, third embodiment according to Fig. 4, fourth embodiment according to Fig. 5 and fifth embodiment according to Fig. 6) is assigned to an electrochemical cell, namely an electrolysis cell 14 (see Fig. 7) or a fuel cell 12 (see Fig. 8).

[0086] The reinforcing element 30 is designed in the form of a structural element that reinforces the mechanical stability of the respective fuel gas electrode 20, namely as a mesh, web or honeycomb structure, as a metal sheet or mesh, as a coarse-porous structure and / or as a, for example, ceramic, plate or metal (perforated) plate or metal (perforated) sheet.

[0087] The reinforcing element 30 has a thickness of approximately 100 micrometers to approximately 400 micrometers, for example from approximately 150 micrometers to approximately 250 micrometers.

[0088] A protective layer may be provided on a section or area of ​​the reinforcing element 30 facing the active and / or functional, finely porous layer 24 of the fuel gas electrode 20 in order to prevent or at least limit a reaction of the reinforcing element 30 with the active and / or functional, finely porous layer 24 of the fuel gas electrode 20.

[0089] As can be seen from the respective illustrations in the first embodiment according to Fig. 2, the second embodiment according to Fig. 3, the third embodiment according to Fig. 4, the fourth embodiment according to Fig. 5 and the fifth embodiment according to Fig. 6, the reinforcing element 30 has meshes or holes 32 with a diameter in the range of about 50 micrometers to about 500 micrometers, wherein the geometries of these meshes or holes 32 may differ in the central region of the fuel gas electrode 20 from those in the outer region of the fuel gas electrode 20. R.415381

[0090] - 11 -

[0091] In the first embodiment according to Fig. 2, in the second embodiment according to Fig. 3 and in the third embodiment according to Fig. 4, highly porous filler material 18 (= the material from which the coarse-porous substrate or support area 22 of the fuel gas electrode 20 is also formed) is completely printed into the meshes or holes 32 of the reinforcing element 30, so that the meshes or holes 32 in the reinforcing component 30 are completely filled with fuel gas electrode material 18;

[0092] In the fourth embodiment according to Fig. 5, highly porous filling material 18 is used.

[0093] (= the material from which the coarse-porous substrate or support area 22 of the fuel gas electrode 20 is also formed) partially, namely up to about half the height in the area of ​​the meshes or holes 32 of the reinforcing element 30 facing the coarse-porous substrate or support area 22 of the fuel gas electrode 20, printed, so that the meshes or holes 32 in the reinforcing component 30 are partially, namely about half filled with fuel gas electrode material 18;

[0094] In the fifth embodiment according to Fig. 6, no or virtually no filler material 18 is printed into the meshes or holes 32 of the reinforcing element 30, so that the meshes or holes 32 in the reinforcing component 30 are not filled at all or at most minimally with fuel gas electrode material 18.

[0095] After the filling material 18 is printed into the meshes or holes 32 of the reinforcing element 30, at least one further layer of the fuel gas electrode 20, in particular the active and / or functional, finely porous layer 24 of the fuel gas electrode 20,

[0096] - printed directly or

[0097] - printed onto a transfer substrate, in particular onto polymer film, and then laminated onto the coarse-porous substrate or support area 22 of the fuel gas electrode 20.

[0098] Fig. 7 shows an electrolysis cell device 36 for producing hydrogen from electricity and water. The electrolysis cell device 36 has an electrolysis cell stack 38, which comprises multiple or a plurality of stacked electrochemical cells configured as cathode-supported electrolysis cells 14. By way of example, the cathode-supported electrolysis cells 14 are configured as high-temperature solid oxide electrolysis cells. The electrolysis cell stack 38 is

[0099] - via a basic material supply 40 with water as the basic material and

[0100] - via a power electronics unit 42 with electric current R.415381

[0101] - 12 -

[0102] The system is supplied with hydrogen. Optionally, an air or oxygen supply can be provided for the anode. The hydrogen and air can be metered by means of electronic controls, which operate corresponding valves and fans.

[0103] Fig. 8 shows a fuel cell device 44 for generating electricity from hydrogen and air. The fuel cell device 44 has a fuel cell stack 48, which comprises multiple or a plurality of stacked electrochemical cells configured as fuel cells 12. By way of example, the fuel cells 12 are configured as high-temperature S[olid]O[xide]F[uel]C[ells]. The fuel cell stack 48 is

[0104] - via a fuel supply 50 with hydrogen as fuel and

[0105] - via an air supply 52 with air

[0106] The hydrogen and air can be metered by means of a control electronics unit 54, which controls corresponding valves and fans. The voltage drawn from the fuel cell stack 48 is converted according to demand by a power electronics unit 42.

Claims

R.415381 - 13 - Claims 1. A fuel gas electrode (20) attributable to an electrochemical cell, in particular an electrolysis cell (14) that is, for example, cathode-supported, or a fuel cell (12) that is, for example, anode-supported, comprising at least one reinforcing element (30) attributable to the fuel gas electrode (20), in particular one that is wholly or partially embedding in the fuel gas electrode (20), and stabilizing the fuel gas electrode (20), in particular a substrate or support area (22) of the fuel gas electrode (20), which may be designed in the form of at least one structural element that reinforces the mechanical stability of the fuel gas electrode (20), in particular as at least one mesh, web or honeycomb structure, as at least one metal sheet or mesh, as at least one coarse-pored structure or as at least one plate, for example, ceramic.

2. Fuel gas electrode according to claim 1, characterized in that the reinforcing element (30) comprises: - a thickness of approximately 100 micrometers to approximately 400 micrometers, in particular from approximately 150 micrometers to approximately 250 micrometers; and / or - at least one coating to increase electrical and / or electronic conductivity; and / or - at least one protective layer, in particular to prevent a reaction of the reinforcing element (30) with an active and / or functional, for example fine-porous, layer (24) of the fuel gas electrode (20).

3. Fuel gas electrode according to claim 1 or 2, characterized in that the reinforcing element (30) has meshes or holes (32), in particular with, for example in the central region of the fuel gas electrode (20) compared to the edge region of the fuel gas electrode (20), different geometries of the meshes or holes (32) and / or - with a diameter of the meshes or holes (32) in the range of about 50 micrometers to about 500 micrometers, wherein the meshes or holes (32) may be wholly or partially filled with, in particular highly porous, filling material (18), for example with the same material from which the substrate or support area (22) of R.415381 is made. - 14 - The fuel gas electrode (20) is formed.

4. Fuel gas electrode according to at least one of claims 1 to 3, characterized by at least one gas path arranged in the fuel gas electrode (20), in particular in the substrate or support area (22) of the fuel gas electrode (20), in particular designed as a gas transport path, for example designed as a fuel gas transport path.

5. Fuel gas electrode according to claims 3 and 4, characterized in that the respective mesh or hole (32) is designed as the respective gas path.

6. Method for producing a fuel gas electrode (20) according to claim 5, characterized in that the filling material (18) is printed wholly or partially into the meshes or holes (32).

7. Method according to claim 6, characterized in that after printing the filling material (18) into the meshes or holes (32), at least one further layer of the fuel gas electrode (20), in particular the active and / or functional layer (24) of the fuel gas electrode (20), is printed directly or printed on at least one transfer substrate, in particular on at least one polymer film, and then laminated onto the substrate or support area (22) of the fuel gas electrode (20).

8. Electrochemical cell, in particular, for example, a cathode-supported electrolysis cell (14) or, for example, an anode-supported fuel cell (12), characterized by at least one fuel gas electrode (20), in particular produced according to the method according to claim 6 or 7, according to at least one of claims 1 to 5.

9. Electrolysis cell device (36) for producing fuel, in particular hydrogen, from electric current and at least one feedstock, in particular water, comprising at least one electrolysis cell stack (38), at least one feedstock inlet (40), in particular water inlet, further comprising at least one exhaust gas routing associated with the fuel gas electrode (20), in particular the cathode, and at least one of the R.415381 - 15 - air electrode (80), in particular the anode, exhaust gas routing associated with it, as well as at least one control electronics (54) and at least one power electronics (42), wherein the electrolysis cell stack (38) comprises at least one electrochemical cell designed as, in particular, a cathode-supported electrolysis cell (14) according to claim 8.

10. Fuel cell device (44) for generating electricity from a fuel, in particular hydrogen and / or natural gas, and air, comprising at least one fuel cell stack (46), at least one fuel supply (50), at least one air supply (52), at least one exhaust gas guide associated with the fuel gas electrode (20), in particular the anode, and at least one exhaust gas guide associated with the air electrode (80), in particular the cathode, as well as at least one control electronics (54) and at least one power electronics (42), wherein the fuel cell stack (46) comprises at least one electrochemical cell designed as a fuel cell (12), in particular anode-supported, according to claim 8.

Images