TW201842704A - Electrode-electrolyte assembly - Google Patents

Abstract

The present invention relates to an electrode-electrolyte assembly (10,10',10",10''') for a metal-supported electrochemical module (20), more particularly for a solid-oxide fuel cell (SOFC). This assembly comprises a metallic support substrate (11) having a porous, gas-permeable central region (13) and an edge region (12) which is joined fusionally to the central region along an edge section thereof, and which is gastight at least superficially (on the cell-facing side), the gas-permeable surface of the porous central region being separated from the gastight surface of the edge region by a borderline (19). It further comprises at least one porous, gas-permeable first electrode (16, 16') formed on the porous central region of the support substrate, and at least one ceramic gastight electrolyte layer (18) which is formed on the first electrode, which extends beyond the first electrode in the edge region direction, and which finishes gastightly (with the gastight edge region). Between support substrate (11) and electrolyte layer (18), at least along a partial section of the overall connecting length of the borderline, at least one porous, ceramic attachment layer (17, 17') is formed which extends at least over a section of the edge region that is adjacent to the borderline.

Description

 Electrode-electrolyte assembly  

The present invention relates to an electrode-electrolyte assembly for an electrical module for metal support according to claim 1, and to an electrochemical module according to claim 21.

The electrode-electrolyte assembly of the present invention is used in an electrochemical module, which can be used as a high-temperature fuel cell or a solid oxide fuel cell (SOFC) as a solid oxide electrolytic cell. (SOEC; solid oxide cell battery) and also used as a reversible solid-Oxide fuel cell (R-SOFC) or the like. In a basic configuration, the electrochemically active cell of the electrochemical module comprises a gas impermeable solid electrolyte disposed between the gas permeable anode and the gas permeable cathode. Here, the electrochemically active components, such as the anode, the electrolyte and the cathode, are frequently designed as relatively thin layers. Thus, the desired mechanical support function may be provided by one of the electrochemically active layers, such as by an electrolyte, an anode or a cathode (eg, each in each case designed to have a corresponding thickness (in which case the system is respectively An electrolyte-supported battery, an anode-supported battery or a cathode-supported battery) is provided, or provided by a component designed to be separated from such functional layers, such as a conductive ceramic or metal support substrate. In the case of the latter approach, in the case of a separately designed metal support substrate, the system is referred to as a metal substrate supported battery (MSC; metal supported battery). In view of the fact that in the case of MSC, the electrolyte with reduced resistance as the thickness decreases and the temperature increases can be given a relatively thin design (eg, having a thickness ranging from 2 to 10 μm), the MSC can be at about 600. Operating at relatively low operating temperatures from °C to 800 °C (and, for example, the electrolyte supported battery operates under operating conditions at operating temperatures up to 1000 °C). Due to its particular advantages, the MSC is particularly suitable for mobile applications, such as electrical supply suitable for passenger cars or commercial vehicles (APU-Auxiliary Power Units).

An electrochemically active battery cell is typically designed as a flat individual component that is configured such that one component in combination with a corresponding (metal) outer casing portion (eg, interconnector, frame panel, gas line, etc.) over another component to form a stack, and Electrically connected in series. In this regard, MSC has the great advantage that the connection and sealing of the individual modules used to form the stack can be achieved at low cost by means of welding or metal welding operations.

In order to operate the electromodulation module, it is necessary to have the process gas spaces assigned to the two electrodes - that is, the anode gas space and the cathode gas space - have a reliable gas-tight separation from each other and even under heat or oxidation load occurring during operation. This airtight separation is also maintained. In the case of SOFC, this means that the fuel (eg, hydrogen or conventional hydrocarbons such as methane, natural gas, biogas, etc.) is reliably separated from the oxidant supplied to the cathode, which is supplied to the anode. In the region of the electrochemically active layer, this gas separation function is carried by the gas impermeable electrolyte, with significant challenges relative to the seal in the transition zone from the porous support substrate to the subsequent gas impermeable surface. In WO2014187534, the applicant of the present invention presents a metal support substrate which is produced by powder metallurgy and has a porous central region on which an electrochemical active layer is disposed, which is wound by a pressed edge region. The surface is rendered non-breathable by additional melting, by laser treatment, and is thus given a hermetic seal. In order to seal between the anode gas space and the cathode gas space, the electrolyte layer is drawn over the porous zone having the anode layer such that it terminates on the gas impermeable surface of the edge region post-processed by the laser beam. However, in practice, this transition zone from the porous central zone to the gas impermeable edge zone represents a weakness and airtightness may be problematic. For example, in the transition zone, the stratification of the layers occurs again and again and can be attributed to irregularities (snake in some cases) including the edge regions caused by the laser beam melting procedure. Structural factors.

The object of the present invention is to produce an electrochemical module for metal support, and more particularly an electrode-electrolyte assembly for SOFC that ensures reliable separation of the two process gas spaces during use in a long period of time and is therefore simple And an inexpensive way to ensure a reliable separation of the two process gas spaces.

This object is achieved by the electrode-electrolyte assembly of claim 1 and the electrochemical module according to claim 21. Advantageous developments are specified in the subsidiary items.

The electrode-electrolyte assembly of the present invention can be used in a metal-supported electrochemical module, more specifically in a high-temperature fuel cell or a solid oxide fuel cell (SOFC), for a solid oxide electrolytic cell (SOEC; solid In an oxide cell battery) and/or in a reversible solid oxide fuel cell (R-SOFC). It has a metal, more specifically a plate shape, a support substrate having a porous, gas permeable central zone and an edge zone joined to the central zone along its edge sections in a fused manner and at least on the surface It is airtight on the side facing the battery. The gas permeable surface of the support substrate in this configuration is separated from the gas impermeable surface on at least the surface of the edge region by a boundary. At least one porous, gas permeable first electrode and at least one gas impermeable ceramic electrolyte layer disposed on the porous central region of the support substrate, the at least one gas impermeable ceramic electrolyte layer extending beyond the first electrode in the direction of the edge region And ending with the airtight edge region of the support substrate in an airtight manner. Between the support substrate and the electrolyte layer, at least a portion of the total connection length along the boundary forms at least one porous, ceramic attachment layer that extends at least over a section adjacent the edge region of the boundary.

The central and edge regions of the support substrate can be two components that are initially separated from one another, which are joined to one another, for example by fusion bonding, such as by fusion or solder joints. In a preferred embodiment, the central zone and the edge zone are implemented in a single piece (single piece), wherein the support substrate is in each case composed of two conceptual components of the fusion contact.

In this case, the edge region is at least on the side of the support substrate facing the electrochemically active layer (for example as described in WO2014187534) by means of, for example, edge-side pressing of the porous support substrate and/or by extensive surface melting in the edge regions. It is not breathable on the surface.

Common to these different designs of the support substrate is that in the central region of the support substrate, there is a gas permeable region, and at least the surface of the edge region is gas impermeable. The interface of the disposed gas permeable surface and the gas impermeable surface defines a boundary (boundary) wherein the surface having the gas impermeable weld or weld is assigned to the gas impermeable surface.

The metal support substrate is preferably produced by powder metallurgy. In particular, suitable materials for supporting the substrate include an iron (Fe) based alloy (ie, containing at least 50 wt%, more specifically at least 70 wt% of Fe), and including a high chromium portion (chromium: Cr) (eg, At least 16% by weight of Cr) to which additional additives such as yttria (Y ₂ O ₃ ) (for increasing oxidation resistance), titanium (Ti) and molybdenum (Mo), part of such additives may be added thereto The total is preferably less than 3% by weight (see, for example, the Plansee SE material designated as ITM and containing 71.2 wt% Fe, 26 wt% Cr, and total less than 3 wt% Ti, Y ₂ O ₃ and Mo). It is preferable to use a powder portion having an average particle diameter of 150 μm, more specifically, in the region of about 50 to 100 pm, in order to secure good coatability for the functional layer.

In the central region of the support substrate, an electrochemically active layer such as a first electrode and a second electrode (anode, cathode) and an electrolyte layer are disposed. The electrode is a gas permeable design and can be constructed as a single layer or as a layer assembly composed of a plurality of layers. Typically, the anode is the electrochemically active layer (first electrode) immediately following the support substrate, and the cathode (second electrode) is formed on the side of the electrolyte that faces away from the support substrate. Alternatively, however, a reverse configuration of the two electrodes is also possible, wherein the first electrode is formed by a cathode. The electrochemically active layer is preferably applied in a known manner, for example by PVD (PVD: physical vapor deposition), sputtering, and/or by thermal coating methods such as flame spraying or plasma Spraying; and/or by wet chemical methods such as screen printing, wet powder coating, etc.; in order to achieve the entire layer structure of the electrochemical cell, two or more of these methods may also be combined Use.

The anode is typically made from a composite called cermet, which is preferably composed of nickel and zirconia which are sufficiently stabilized with yttria or consists of nickel and yttrium oxide doped with yttria, while the cathode is usually It is formed of a perovskite having a mixed conductivity such as (La,Sr)(Co,Fe)O ₃ . In particular, the first electrode can be of a multi-layer design and can have a graduated configuration in which the average sintered grain size decreases layer by layer as the distance from the support substrate increases.

After the first electrode, a gas-tight solid electrolyte comprising a solid, ceramic metal oxide material is between the two electrodes, the solid, ceramic metal oxide material is conducted for the oxygen ion system, or the state in which the SOFC is newly produced Next, for protons and not for electrons. An example of an electrolyte layer material that conducts oxygen ions is: doped zirconia in which at least one oxide containing doping elements from the group of Y, Sc, Al, Sr, Ca, Mg is doped (eg, 8YSZ, Zirconium dioxide sufficiently stabilized with 8 mol% of cerium oxide; or doped cerium oxide, wherein the doping comprises groups of rare earth elements such as Gd, Sm and/or from Y, Sc, Al, Sr, Ca At least one oxide of a group of doping elements. Examples of proton conducting electrolyte materials are cerium zirconium oxide, cerium oxide, cerium tungsten oxide or cerium oxide. The electrolyte layer typically has a layer thickness ranging from 3 to 5 [mu]m and is typically applied by PVD. The electrolyte layer extends beyond the layer of the first electrode and terminates in an airtight manner with the gas impermeable edge regions of the support substrate. "Airtight" in the context of the present invention means, in particular, that for a sufficient airtightness, the leakage rate is <10 ^-3 hPa*dm ³ /cm ² s on a standard basis (hPa: hectopascal, dm ³ : cubic Inch, cm ² : square centimeter, s: second) (using an instrument from Dr. Wiesner, Remscheid model: Integra DDV measured by air pressure at dp = 100 hPa). For hermeticity, the electrolyte layer may be in direct contact with the gas impermeable surface of the edge region of the support substrate, or may be terminated directly on one or more of the support substrates that are optionally airtight. For example, such a interlayer that is impermeable to at least the edge region can be provided by the diffusion barrier layer, the diffusion barrier layer being designed to prevent metal interdiffusion between the support substrate and the anode, and also due to its production, at the edge One part of the area extends. The diffusion barrier layer preferably comprises different doped lanthanum sulphate manganite (LSM), lanthanum sulphate (LSCr) or lanthanum oxide doped with different lanthanum and cerium contents. Cerium oxide (CGO); the diffusion barrier layer is typically applied directly to the support substrate by PVD; the layer thickness is typically up to 2 μm and is therefore relatively thin (compared to the average pore size of the support substrate in the center, gas permeable region) It may be of the order of 100 [mu]m whereby the gas permeability is maintained in the porous, central zone). Therefore, the boundary separating the gas impermeable region from the gas permeable region of the surface of the support substrate remains unchanged even in the case of coating.

The core concept of the present invention is to provide at least one additional, porous, ceramic attachment layer in the edge region of the support substrate between the electrolyte layer and the support substrate (or any gas impermeable interlayer disposed thereon). This interlayer in the edge region serves to compensate for irregularities in the surface of the edge region and thus can have different layer thicknesses throughout its profile. Preferably, it becomes thinner and depleted towards its edges. By means of the attachment layer, it is possible to compensate or smooth out irregularities caused by, for example, the aforementioned laser tracking during the surface melting process, or sharp gradations or inconsistencies at the transition between the first electrode and the surface of the edge region . Due to the flattening, a more uniform surface is provided for applying a relatively thin electrolyte layer, thereby significantly reducing mechanical weakness and the risk of cracking in the gas-tight, very thin electrolyte layer. The porous attachment layer additionally helps to compensate or reduce the load generated by the different coefficients of thermal expansion of the materials used in the transition zone. Different coefficients of thermal expansion for supporting the substrate, the electrode and the electrolyte layer generate stresses in the layer structure during the sintering operation and/or in later operations, especially during production, which may cause cracking or delamination, And then caused the failure of the electrochemical module.

An additional advantage of the attachment layer is the improvement of the adhesion of the layer structure in the critical transition zone. The attachment layer is preferably a sintered ceramic layer joined to the support substrate via a sintered neck (or to an airtight interlayer, optionally selected). It is preferably applied by wet chemical methods (e.g., wet powder coating, brush coating, screen printing, etc.) prior to subsequent sintering. If a relatively fine initial powder is used for the attachment layer (which produces a small average pore size), the adhesion of the attachment layer is additionally improved by the formation of a relatively large number of sintered necks. The risk of delamination during sintering as part of the manufacturing process and during subsequent use is significantly reduced. In an advantageous embodiment, the average pore size of the sintered attachment layer is smaller than the average pore size of the first electrode (in the case of a multilayer first electrode having a difference in porosity, the pore size for comparison is positioned to be closest The pore size of the lowest layer supporting the substrate). The preferred average pore size for the attachment layer is in the range from 0.20 pm (including 0.20 pm) and includes 2.00 pm, more specifically in the range from 0.31 pm (including 0.31 pm) and including 1 pm. More preferably, it is still in the range from 0.31 pm (including 0.31 pm) and includes 0.5 pm. In general, in the case of data relating to the pore size or other similar parameters, the reference frame is for the parameters in the ready-to-use state - that is, in the case of the layer to be sintered, for the sintered state. In order to determine the porosity, a cross section perpendicular to the layer to be studied is made by the electrode-electrolyte assembly, and based on SEM-BSE image (BSE: reversely dispersed electron) in a scanning electron microscope (SEM) The grounding section prepared correspondingly is checked. This analysis is based on thresholds for different gray levels from individual SEM-BSE images, where the brightness and contrast of the SEM-BSE images are adjusted such that the pores and particles in the image are readily detectable and distinguishable from one another. In the case of using a slider that distinguishes pores from particles according to the gray level, the appropriate gray level is selected as the threshold. Porosity is determined by determining the area of the void in the selected zone relative to the total area of the selected zone; this calculation should also include a partial area of the void that is only partially within the selected zone. In order to determine the pore size, the area of each of the pores in the ground section is measured and judged based on the equivalent diameter of the pores, as would occur in the case of a ring shape having the same size region.

In terms of the geometrical boundaries of the attachment layer, it has emerged to be advantageous for the attachment layer to extend from the boundary up to and including the maximum length of 3 cm in the direction of the edge zone, more particularly up to and including 2 cm, particularly advantageous. The ground is included in 1cm. In the opposite direction, in other words, in the direction of the central region of the support substrate, the attachment layer advantageously extends up to and including a maximum length of 1 cm, more specifically up to and including 0.5 cm, from the boundary, which is particularly advantageous. It is up to and includes 0.3cm. For such sized details of the attachment layer, a good compromise has been found between good adhesion properties and inexpensive production.

In order to promote adhesion, it is further advantageous if at least in the partial section of the edge region the adhesion layer and the electrolyte layer and the support substrate or the gas-impermeable ceramic interlayer (if the support substrate is covered with an airtight ceramic interlayer at the edge) In the district) direct fusion contact.

In the event that a "direct" continuous layer/component is referred to in this specification and in the context of the patent application, the existence of layers/components therebetween is excluded. On the other hand, without adding "direct", it is also possible to provide additional layers/components between them in a technically sound manner.

The attachment layer is preferably constructed of the same base material as the electrolyte layer. Thereby, it is possible to particularly prevent or reduce the thermally induced stress in the transition zone and to improve the adhesion by using the electrolyte layer. According to the electrolyte material given above, a suitable material for the adhesion layer is: doped zirconia, wherein the doping comprises doping elements from the group of Y, Sc, Al, Sr, Ca, Mg. At least one oxide (especially 8YSZ); or doped cerium oxide, wherein the doping comprises a group of rare earth elements such as Gd, Sm and/or a group of groups from Y, Sc, Al, Sr, Ca At least one oxide of a hetero element (especially CGO). Further suitable materials for the attachment layer are cerium cerium oxide, cerium oxide, cerium tungsten oxide or cerium oxide.

For a variation of the electrode-electrolyte assembly in which the support substrate is coated with an air impermeable interlayer such as a diffusion barrier layer on the edge region, the material of the attachment layer is suitable for the material of the gas impermeable interlayer. . If the same base material as the gas-impermeable interlayer is selected for the attachment layer, the adhesion layer and the gas-impermeable interlayer and the adhesion to the support substrate are stronger.

In order to produce an electrode-electrolyte assembly, various layers (optionally, a diffusion barrier layer, a first electrode, an attachment layer, and an electrolyte layer) are successively applied to the support substrate. In the case of a layer intended for sintering, such as a porous attachment layer, the layer comprising the individual ceramic particles and the corresponding organic binder is applied via a wet chemical method followed by sintering, and then a subsequent layer can be applied ( In a similar manner when appropriate). Individual layers may be distinguished from each other for reasons including layer-by-layer sintering, even if they have the same composition. For example, if the cross section of the cross section of the layer is made by the electrode-electrolyte assembly and the corresponding preparation is performed under a scanning electron microscope (SEM) based on SEM-BSE image (BSE: backscattered electron) In the district section, the layer construction system is detectable.

In this case, the attachment layer can be applied before or after the application of the first electrode, as explained in more detail below, which can also be realized in multiple layers as an assembly of layers. Moreover, in a preferred variant, a plurality of and more particularly two attachment layers are provided: a first attachment layer applied prior to application of the first electrode; and a second attachment layer applying the first The electrodes are then applied.

In a first embodiment in which an attachment layer is applied prior to the layer of the first electrode, the attachment layer is in direct fused contact with the support substrate or a ceramic interlayer that is directly coated with the support substrate. The attachment layer is thinned toward its ends and can penetrate the material of the support substrate in an excessive region to the porous central region of the support substrate. Thus, in particular in the specific example of the support substrate constructed from the first two separate components, the layer thicknesses may be different, the two separate components being connected to each other by a welded or welded connection. In this case, the attachment layer is typically thicker in the fusion bonded (weld) region. The layer of the first electrode terminates at or above the attachment layer; in the case of a multilayer embodiment, the lowest layer of the assembly closest to the layer supporting the substrate may terminate at the attachment layer, while the subsequent layers may each extend beyond the positive The bottom layer can be terminated on the attachment layer. A specific example in which the attachment layer is applied before the first electrode has an advantage especially in the case of the electrode-electrolyte assembly, wherein a gas-impermeable ceramic interlayer (diffusion barrier layer) is provided and the first electrode is made of cermet . A ceramic attachment layer having a relatively fine porosity, as the case may be, is typically more effectively adhered to the ceramic substrate than a layer of cermet.

In another embodiment in which the attachment layer is applied after the first electrode, the attachment layer is in direct fusion contact with the subsequent electrolyte layer.

This variant provides advantages, inter alia, in the case where the attachment layer and the electrolyte layer are made from the same material and thus promote good adhesion between the layers. Here, the layer thickness of the attachment layer is also varied to compensate for sharp edges, stepped transitions in the condition of the first electrode, and to provide a uniform substrate to the subsequent electrolyte layer. In order to achieve better adhesion in the transition zone, care should be taken to ensure that the first electrode layer, or in the case of a multilayer embodiment, the lowest of the first electrode layers, that is, the layer closest to the support substrate. Extending over the entire porous central region of the support substrate, but not extending beyond it; in other words, the layer of the first electrode that is coarser than the subsequent layer or the lowest layer thereof extends in the edge direction to the gas permeable region and the support substrate The boundary of the gas impermeable zone separation (or coated support substrate) (except for small gaps that may occur due to the manufacturing process), but does not extend beyond the boundary significantly. By quantification, this means that the (lowest) layer of the first electrode extends in the edge direction over the gas permeable surface of the porous support substrate towards the boundary by a distance of at least 2 mm, more specifically up to a distance of 1 mm, The distance up to a distance of 0.5 mm, which extends over the boundary in the same direction by a distance of at most 5 mm, preferably at most 3 mm, more preferably at most 1 mm. In other words, the (lowest) layer of the first electrode - except for the region of the maximum distance of 2 mm from the boundary - shields the central gas permeable region of the support substrate, and - except for the region at a maximum distance of 5 mm from the boundary - Extends across the airtight surface of the configuration. The (lowest) layer of the first electrode is here in direct contact with the support substrate or with any interlayer (diffusion barrier layer) applied to the support substrate. Direct contact of the (lowest) layer of the first electrode with the gas impermeable surface of the edge region is largely or completely avoided, which is a problem attributed to the roughness of the adhesion and the associated deficiency.

In the case of this variant, the boundaries of the attachment layer need not be limited to the transition zone; in fact, the attachment layer may extend over the entire first electrode. Due to penetration into the pores of the highest layer of the first electrode, the surface roughness is reduced, which means that a slightly thinner electrolyte layer is sufficient for sealing. In view of the appropriate combination of materials, such as the CGO of the anode made of Ni/8YSZ, this layer can be additionally functionalized; in the CGO example, in view of the sulfur tolerance of CGO, it can be made less sensitive to sulfur impurities in fuel gas. .

In a preferred embodiment, the two variants described above are combined and two attachment layers are provided to allow the above identified advantages to be achieved. The first attachment layer is disposed directly on the support substrate or on a support substrate coated with a gas impermeable ceramic interlayer.

A first electrode is applied first, which terminates at or above the first attachment layer. This is followed by a second attachment layer, which preferably has the same material as the first attachment layer. At least in the section, this layer is joined in a fused manner with the first attachment layer. In the direction of the central region of the support substrate, it extends at least over a portion of the first electrode, and it can also be completely pulled out of the first electrode and can completely cover the electrode. In the opposite direction, in other words, in the direction of the gas impermeable edge region, the second attachment layer can also be completely pulled out of the first attachment layer such that it is on the support substrate (or directly on the support substrate) The gas impermeable ceramic interlayer is terminated.

As already mentioned above, it is possible to configure the first electrode as an assembly of layers in all of these variants, that is to say with a multi-layer configuration, more particularly with a two-layer configuration. In this case, there is preferably no change in the composition of the material; in fact, the individual layers of the assembly of layers of the first electrode differ only in terms of the average sintered grain size or in association with it in terms of porosity. In this case, the assembly of the layers may be characterized by a gradual change in the grain size of the sintered grains, wherein the average sintered grain size decreases layer by layer as the distance from the support substrate increases.

In the assembly of the layers of the first electrode, the subsequent layer, which is generally finer than the underlying layer, preferably extends in each case beyond the layer directly below it, thus forming a stepped transition in the transition zone. , thus improving the adhesive properties. The bottom layer and/or the subsequent attachment layer compensate for the stepped transition.

In an advantageous embodiment, the assembly of the layers of the first electrode is of two layers. In a specific example in which the first electrode is applied prior to the attachment layer, care should be taken to ensure that the lowest, relatively coarser particle layer of the first electrode extends substantially up to the boundary, but does not extend significantly beyond it, while the first electrode Subsequent finer particle layers extend beyond the lowest layer in the direction of the gas impermeable surface of the support substrate. Thus, the finer particulate layer, rather than the coarser particulate layer, is in direct contact with the gas impermeable surface of the support substrate or any interlayer.

Other advantages of the invention will become apparent from the following description of the exemplary embodiments of the invention, in which FIG. In the various figures, the same reference symbols are used to match components.

In the drawings: FIG. 1 is a schematic cross-sectional view showing an electrode-electrolyte assembly of the present invention according to a first specific example of the present invention; and FIG. 2 is a view showing the present invention according to a second specific example of the present invention. Schematic cross-sectional view of an electrode-electrolyte assembly; FIG. 3 is a schematic cross-sectional view showing an electrode-electrolyte assembly of the present invention in accordance with a third embodiment of the present invention; FIG. 4: showing the invention according to the present invention A schematic cross-sectional view of an electrode-electrolyte assembly of the present invention in a fourth embodiment; FIG. 5: shows an exploded depiction of an electrochemical module having an electrode-electrolyte assembly according to FIG.

Figure 1 depicts a schematic cross-sectional view of a first embodiment of an electrode-electrolyte assembly (10) of the present invention. Figure 5 shows an exploded depiction of an electrochemical module (20) in the form of a SOFC in which the electrode-electrolyte assembly of Figure 1 is used. The cross section of the electrode-electrolyte assembly depicted in Figure 1 is along the line I-II in the support substrate of Figure 5 (remember, in the electrochemical module, also not described in Figure 1 Second final electrode). The support substrate (11) for the electrode-electrolyte assembly is produced by powder metallurgy from iron-chromium alloy according to WO2014187534, preferably from the following: Fe>50 wt% and 15 to 35 wt% of Fe-based Fe Alloy; 0.01 to 2 wt% of one or more elements from the group of Ti, Zr, Hf, Mn, Y, Sc, rare earth metals; 0 to 10 wt% of Mo and/or AI; from Ni, W, Nb, Ta 0 to 5 wt% of one or more metals; 0.1 to 1 wt% of O; the balance being Fe and impurities, wherein at least one metal from the group of Y, Sc, rare earth metals and from Cr, Ti, AI At least one metal of the group of Mn forms a mixed oxide. The powder portion having a particle size of <150 μm is selected so that the surface roughness is kept low enough and good coatability of the subsequent functional layer is ensured. In the edge region (12) surrounding the porous and gas permeable central region (13), the support substrate (11) is densified. On the porous central zone (13), a chemically active layer as seen in the cross-sectional view of Figure 1 is disposed. Densification of the marginal zone is advantageous, but is not essential. In the edge region, on the battery-facing side, the support substrate (11) undergoes extensive surface melting by means of a laser beam. The solidified melt forms an air impermeable surface barrier (14) extending from the outer periphery of the central region (13) until the support substrate (11) is connected to the contact plate (interconnector) in a gas-tight manner by means of a weld Point of (21). The gas permeable surface of the central region (13) of the support substrate is separated from the gas impermeable surface of the edge region (12) of the support substrate by a boundary (19). The boundary edge region (12) of the support substrate is enlarged on two opposite sides with gas passage openings (22) for supplying and removing process gases, respectively.

A diffusion barrier layer (15) made of CGO or LSM and having a thickness of up to about 2 pm is applied as a first layer to the surface of the metal support substrate in the central region (13) by PVD and applied to the edge region ( 12) an adjacent portion that blocks metal interdiffusion between the support substrate (11) and the first electrode (16, 16') (in the case of an SOFC, an anode) (in the porous central region (13), pores Not closed by the diffusion barrier layer (15) and thus still providing gas permeability). Next is a first electrode consisting of two layers (16, 16') having different average sintered grain sizes and porosity. Starting from a coarse particulate metal substrate, the average sintered grain size or pore size of each electrode layer is reduced. The first electrode is produced by layering by applying a suitable paste to each layer by screen printing and then sintering in a reducing hydrogen atmosphere at a temperature exceeding 1000 °C. A scaled construction can of course be improved by using more than two depicted layers. The material selected for the electrode layer is a cermet of nickel and zirconium dioxide (Ni/8YSZ) which is sufficiently stabilized by yttrium oxide. The lowest layer (16) of the first electrode covers the entire porous central region (13) of the support substrate (11) up to the boundary (19) (except for small gaps that may occur due to the manufacturing process), but does not extend to significantly exceed The boundary (19). Only the subsequent finer particle layer (16'), which has better adhesion than the lowest layer (16) due to its finer particle structure, is pulled beyond the lowest layer (16) and boundary (19) and with the diffusion barrier layer (15) Fusion contact. The subsequent layer applied in the transition zone of the gas impermeable edge region (12) is a porous ceramic attachment layer (17) of 8YSZ or CGO by brushing the corresponding powder suspension and adding, for example, a dispersant, solvent (eg , available as BCA 2-(2-butoxyethoxy)ethyl acetate from Merck KGaA, Darmstadt, and a binder, followed by a hydrogen atmosphere at about 1000 ° C to 1300 ° C Sintering is applied in a wet chemical manner. A fine particle powder having a d80 of about 2 μm (and having a d50 of about 1 μm) was used, and an average pore size ranging from 0.2 pm up to (and including) 1 pm was established. For better adhesion, a finer powder can be blended into the powder. The fine particle attachment layer (17) helps to compensate for serpentine irregularities on the surface of the support substrate that are otherwise locally smooth due to laser tracking during the melt operation, and compensate for sharp transitions in the condition of the first electrode And is a thin electrolyte layer (18) with a more even transition of the substrate. The attachment layer (17) extends beyond the first electrode and terminates in the direction of the edge of the support substrate (11). In the region of the electrode, due to the porosity of the first electrode, it can penetrate into the electrode more or less and fill the pores in the highest electrode layer to some extent. This penetration into the pores can additionally contribute to the adhesion and sealing of the electrolyte (18) in the zone. On one side, the attachment layer (17) is in direct contact with the subsequent electrolyte layer (18), and on the other side, it is in direct contact with the ceramic diffusion barrier layer (15) and has been coated on the diffusion barrier layer. In the inventive example in which the reticle is applied and does not extend over the entire support substrate, it is also in contact with the surface of the metal support substrate. The electrolyte layer (18) is applied by PVD, has a thickness of less than 5 pm, and is composed of 8YSZ. It achieves a gas-tight separation of the first electrode from the second electrode. The second electrode (in the case of SOFC, the cathode) is likewise applied to the electrolyte (18) by screen printing and is opposed to the first electrode (the second electrode is not depicted in Figure 1).

The specific example depicted in FIG. 2 differs from the specific example in FIG. 1 in the application sequence of the first electrode and the attachment layer. In the case of this variant, the ceramic porous attachment layer (17') of 8YSZ or CGO is placed directly on the support substrate (11) coated with the diffusion barrier; the layer of the first electrode (16, 16') follows it It is then terminated at or above the attachment layer (17'). The attachment layer (17') projects slightly over the edge region (12) into the central region (13) of the support substrate (11). Since the support substrate (11) has a relatively large aperture in the unpressed central region (13), the porous attachment layer (17') penetrates into the pores of the support substrate (11).

Figure 3 shows a third specific example with two attachment layers (17, 17'): a first attachment layer (17'), which is placed directly adjacent to the variant of Figure 2, coated with a diffusion barrier ( 15) on the support substrate (11); and a second attachment layer (17) similar to the variant of Figure 1 applied after the first electrode (16, 16'). The second attachment layer (17) may extend in the direction of the central zone and may extend over the entire first electrode (16, 16'). The effect of the second attachment layer (17) is not only to produce smoothness in the transition zone but also to reduce the surface roughness of the first electrode, thus allowing the thickness of the electrolyte layer (18) to be reduced.

Figure 4 shows a specific example of an electrode-electrolyte assembly (10'") in which the support substrate (11) is made of two initially separated components: a metal, porous substrate portion (13) which is produced by powder metallurgy. And welded to the frame plate (12) with limited airtightness. In this example, the challenge of sealing is primarily a relatively deep and sharp weld. Similar to the previous example, the porous substrate portion is made of an iron chromium alloy. In this case, coating is performed and the diffusion barrier layer (15) is not covered. Similar to the illustrative embodiment of Figure 3, two attachment layers (17, 17') are used. Variations having an attachment layer as in Figure 1 or Figure 2 are also contemplated. If the first electrode (16, 16') is applied before the attachment layer, care should be taken to ensure that at least the lowest relatively coarser particle layer of the first electrode is not in contact with the weld groove, but in fact the local smooth weld is for The purpose of good adhesion is directly covered with a finer layer of particles, such as an attachment layer of the first electrode or a subsequent finer layer of particles.

Claims (21)

 An electrochemical module (20) for a metal support, and more particularly for an electrode-electrolyte assembly (10, 10', 10", 10"') of a solid oxide fuel cell (SOFC) And comprising: a metal supporting substrate (11) having a porous, gas permeable central region (13) and an edge region (12), the edge region (12) being fused along an edge portion thereof Means joined to the central region and at least surfacely impermeable to the side facing the battery, the gas permeable surface of the porous central region (13) and the gas impermeable surface of the edge region (12) being bordered by (19) separating, at least one porous, gas permeable first electrode (16, 16') formed on the porous central region of the support substrate, at least one ceramic gas impermeable electrolyte layer (18) formed Extending on the first electrode (16, 16') beyond the first electrode in the direction of the edge region and in an airtight manner with the gas impermeable edge region, the electrode-electrolyte assembly is characterized in that Between the support substrate (11) and the electrolyte layer (18), at least one of the overall connection lengths along the boundary is segmented At least one porous ceramic layer attachment (17, 17 '), which extends at least in one section adjacent to the edge region (12) of the boundary.    The electrode-electrolyte assembly of claim 1, wherein the attachment layer (17, 17') has an average pore size that is smaller than the first electrode (16, 16').    The electrode-electrolyte assembly of any one of claims 1 to 2, wherein the attachment layer (17, 17') is a sintered ceramic layer.    The electrode-electrolyte assembly of any one of claims 1 to 3, wherein the attachment layer (17, 17') extends from the boundary (19) in the direction of the edge region (12) Up to and including one of the maximum length of 3cm.    The electrode-electrolyte assembly according to any one of claims 1 to 4, wherein the attachment layer (17, 17') starts from the boundary (19) in the central region of the support substrate (11) ( The direction of 13) extends up to and includes one of the maximum lengths of 1 cm.    The electrode-electrolyte assembly according to any one of claims 1 to 5, wherein at least one gas impermeable ceramic interlayer (15) is directly disposed in the edge region (12) of the support substrate (11) The support substrate (11) is formed between the gas impermeable ceramic interlayer (15) and the electrolyte layer (18).    The electrode-electrolyte assembly according to any one of claims 1 to 6, wherein the attachment layer (17, 17') is at least in a portion of the edge region with the electrolyte layer (18) It is in direct contact with both the surface of the support substrate (11) and/or with the gas impermeable ceramic interlayer (15).    The electrode-electrolyte assembly of any one of claims 1 to 7, wherein the attachment layer (17') is directly disposed on the support substrate (11) (and/or on one of the mounting layers) The gas impermeable ceramic interlayer (15) and the first electrode (16, 16') terminate on and/or at the attachment layer (17').    The electrode-electrolyte assembly of any of claims 1 to 7, wherein the attachment layer (17) terminates at or at the first electrode (16, 16').    The electrode-electrolyte assembly according to any one of claims 1 to 9, wherein the first electrode (16, 16') is in a multi-layer form, and in each case, a directly following electrode layer ( 16') extends beyond the underlying electrode layer (16').    The electrode-electrolyte assembly according to any one of claims 1 to 10, wherein a lowest layer of the first electrode (16) faces in a direction of the edge region on a surface of the central region of the support substrate The boundary (19) extends at least one distance of 2 mm.    The electrode-electrolyte assembly of any one of claims 1 to 11, wherein the lowest layer of the first electrode (16) extends over the gas impermeable surface of the edge region in the direction of the edge region The boundary (19) is at least one distance of 5 mm.    The electrode-electrolyte assembly according to any one of claims 1 to 12, wherein the attachment layer (17, 17') is composed of the same material as the electrolyte layer (18).    The electrode-electrolyte assembly according to any one of claims 1 to 13, wherein the attachment layer (17, 17') and/or the electrolyte layer (18) is composed of doped zirconia, doped At least one oxide comprising doping elements from the group of Y, Sc, Al, Sr, Ca, Mg.    The electrode-electrolyte assembly according to any one of claims 1 to 14, wherein the attachment layer (17, 17') and/or the electrolyte layer (18) is composed of doped cerium oxide, doped At least one oxide comprising a group of rare earth elements such as Gd, Sm and/or a dopant element from the group of Y, Sc, Al, Sr, Ca.    The electrode-electrolyte assembly according to any one of claims 1 to 15, wherein the first electrode (16, 16') is composed of a cermet, more specifically, free Ni and YSZ or Ni and CGO. One of the cermet constructions.    The electrode-electrolyte assembly according to any one of claims 1 to 16, wherein the support substrate (11) is produced from an iron-chromium alloy.    The electrode-electrolyte assembly according to any one of claims 1 to 17, wherein the edge region (12) of the support substrate (11) is formed as a bounding frame panel and by means of a welded, welded or warp The adhesive bonding connection is joined to the central region (13) of the support substrate (11) in a fused manner.    The electrode-electrolyte assembly according to any one of claims 1 to 17, wherein the edge region (12) and the central region (13) are produced by powder metallurgy and are integrally formed.    The electrode-electrolyte assembly of claim 19, wherein the edge region (12) on the side facing the battery is rendered gas impermeable by surface melting.    An electro-mechanical module (20), and more particularly an SOFC, comprising the electrode-electrolyte assembly (10, 10', 10", 10"' of any one of claims 1 to 20. ).