阅读说明：本技术 用于电化学模块的多孔的模制件 (Porous molded part for an electrochemical module ) 是由 克里斯汀·比纳特 沃尔夫冈·沙夫鲍尔 马尔科·布兰德纳 于 2018-02-22 设计创作，主要内容包括：本发明涉及一种用于电化学模块(20)的多孔的模制件(10,10‘；10“)。这种电化学模块(20)具有：具有带有至少一个电化学活性层的层结构(23)的至少一个电化学电池单元(21),和金属的气密性外壳(24；25),其与所述的电化学电池单元形成气密性工艺气体空间(26)。所述外壳(24；25)在至少一个侧面上延伸超过所述电化学电池单元(21)的区域,并形成开放到所述电化学电池单元的工艺气体传导空间(27),并且在所述工艺气体传导空间(27)的区域中具有至少一个气体通道开口(28),用于供给和/或除去所述工艺气体。本发明的模制件(10,10‘；10“)被设计为与所述电化学电池单元(21)的独立的部件,并且适于排列在所述工艺气体传导空间(27)内以及用于在两侧上沿着所述电化学模块的堆叠方向(B)支撑所述外壳。(The invention relates to a porous molded part (10, 10 '; 10') for an electrochemical module (20). This electrochemical module (20) is provided with: at least one electrochemical cell (21) having a layer structure (23) with at least one electrochemically active layer, and a metal gas-tight housing (24; 25) which forms a gas-tight process gas space (26) with the electrochemical cell. The housing (24; 25) extends on at least one side beyond the region of the electrochemical cell (21) and forms a process gas conducting space (27) which opens out into the electrochemical cell, and has at least one gas passage opening (28) in the region of the process gas conducting space (27) for supplying and/or removing the process gas. The molding (10, 10 '; 10') of the invention is designed as a separate component from the electrochemical cell (21) and is adapted to be arranged in the process gas conducting space (27) and to support the housing on both sides in the stacking direction (B) of the electrochemical modules.)

1. A porous molded part (10, 10 '; 10') or an at least sectionally porous molded part (10, 10 '; 10') for an electrochemical module (20), wherein the electrochemical module (20) has:

at least one electrochemical cell (21), the electrochemical cell (21) having a layer structure (23) with at least one electrochemically active layer, and

a metallic gas-tight housing (24; 25), the gas-tight housing (24; 25) forming a gas-tight process gas space (26) with the electrochemical cell,

wherein the housing (24; 25) extends beyond the area of the electrochemical cell (21) on at least one side and forms a process gas conducting space (27) which is open to the electrochemical cell and has at least one gas passage opening (28) in the area of the process gas conducting space (27) for supplying and/or removing the process gas,

characterized in that the molding (10, 10 '; 10') is designed as a separate component from the electrochemical cell (21) and is adapted to be arranged within the process gas conducting space (27) and to support the housing on both sides in the stacking direction (B) of the electrochemical modules.

2. The molded article according to claim 1, characterized in that the molded article (10, 10 '; 10') has at least one gas passage opening (11).

3. The molded article according to claim 2, characterized in that the molded article (10, 10 '; 10') is gas-permeable in at least one direction in a plane from the gas channel opening (11) up to a main extent of the side of the molded article.

4. The molded article of claim 3 wherein the gas permeability is created by an open cell structure of the molded article.

5. The molded article according to any one of claims 2 to 4, characterized in that the molded article (10, 10 '; 10') has at least one channel (12) along a main extent plane.

6. The molded article according to claim 5, characterized in that the channel or channels (12) extend continuously from the gas channel opening (11) up to the side edges.

7. Moulded article according to claim 5 or 6, characterised in that the channel or channels (12) extend radially or substantially radially outwards from the gas channel opening in the gas channel opening area.

8. Moulded element according to any one of claims 5 to 7, characterised in that the channels (12) open into the side edges parallel or substantially parallel to each other.

9. A molded part according to any one of claims 5 to 8, characterized in that in the case of a plurality of channels, the cross-sectional area of the channel or channels increases in proportion to the channel length.

10. Moulded article according to any one of claims 5-9, characterised in that the channels (12) extend at least sectionally over the entire thickness of the moulded article.

11. Moulded article according to any one of claims 1-10, characterised in that the moulded article (10, 10'; 10 ") is formed from a ferritic alloy based on iron and/or chromium produced by a powder metallurgy process.

12. Use of a molded part according to any one of claims 1-11 in an electrochemical module (20), wherein the molded part is arranged within the process gas conducting space (27).

13. An electrochemical module (20) having:

a substantially plate-shaped electrochemical cell (21), said cell (21) having: a layer structure (23) with at least one electrochemically active layer, and

a metallic gas-tight housing (24; 25) which forms a gas-tight process gas space (26) with the electrochemical cell (21), wherein the housing (24; 25) extends on at least one side beyond the area of the electrochemical cell (21), the housing (24; 25) forming in this case a process gas conducting space (27) which is open to the electrochemical cell and having at least one gas passage opening (28) in the area of the process gas conducting space (27) for supplying and/or removing the process gas,

characterized in that at least one molding (10, 10 '; 10') according to any one of claims 1 to 11 is arranged in the region of the gas channel opening in the process gas conducting space (27), which molding (10, 10 '; 10') serves to support the housing in the stacking direction (B) of the electrochemical modules (20).

14. Electrochemical module according to claim 13, characterized in that the layer structure (23) is arranged on a first side of a substantially plate-shaped metallic support substrate (22) facing away from the process gas space, the support substrate (22) being porous at least in the region of the layer structure.

15. Electrochemical module according to claim 14, characterized in that the gastight housing (24; 25) is formed by at least one frame panel (25) delimiting the support base and an interconnector (24), wherein the delimiting frame panel (25) is gas-tightly joined at its inner edge to the electrochemical cell (21) and at its outer edge to the interconnector (24) via a connection of a delimiting weld.

Technical Field

The invention relates to a porous molded part for arrangement in an electrochemical module according to claim 1 and to an electrochemical module according to claim 13.

Background

The porous molded parts of the invention are used in electrochemical modules which can be used as high temperature fuel cells or Solid Oxide Fuel Cells (SOFCs), solid oxide electrolysis cells (SOECs; solid oxide electrolyzer cells) and as reversible solid oxide fuel cells (R-SOFCs) and the like. In a basic configuration, the electrochemically active cells of the electrochemical module comprise a gas-tight solid-state electrolyte arranged between a gas-permeable anode and a gas-permeable cathode. The electrochemically active components (here, for example, the anode, the electrolyte and the cathode) are often designed as comparatively thin layers. The resulting required mechanical support function may be provided by one of the electrochemically active layers, for example by the electrolyte, the anode or the cathode, for example each of which is designed with a corresponding thickness in that case (in which case the system is referred to as an electrolyte-supported, anode-supported or cathode-supported cell, respectively), or by a component designed separately from these functional layers, such as a ceramic or metal support substrate, for example. In the case of the latter solution, a separately designed metal support substrate is used, the system being referred to as a metal substrate supported battery (MSC; metal supported battery). Depending on the MSC, the electrolyte (whose resistance decreases with decreasing thickness and increasing temperature) may be given a relatively thin design (e.g., 2 to 10 μm thickness), and the MSC may operate at relatively low operating temperatures of about 600 ℃ to 800 ℃ (while, for example, electrolyte-supported cells operate at operating temperatures of up to 1000 ℃ in some cases). Due to their particular advantages, MSCs are particularly suitable for mobile applications, such as, for example, power supplies for passenger cars or commercial vehicles (APU power plant).

The electrochemically active cell units are typically designed as flat individual elements that are arranged on top of each other, connected with corresponding (metal) housing parts (e.g., interconnectors, frame panels, gas lines, etc.) to form a stack, and are in electrical contact in series. The respective housing parts in the individual cells of the stack bring about the supply of the process gases separately from one another in each case (in the case of a fuel cell, the supply of fuel to the anode and the oxidation to the cathode) and the removal of the gases formed in the electrochemical reaction on the anode side and on the cathode side.

The process gas spaces are in each case formed on either side of the electrolyte in the stack on the basis of a single electrochemical cell. The stack may be configured in a closed structure, in which two process gas spaces, which are in each case joined by the electrolyte and the respective housing part (interconnectors, optionally also by frame panels or else, in the case of MSCs, by edge regions of the support substrate), are sealed in a gastight manner. It is also possible to achieve an open structure for the stack, in which case only one process gas space, in the case of a fuel cell the anode-side process gas space, for example in which fuel is supplied and/or reaction products are withdrawn, is sealed in a gastight manner, while an oxidant (oxygen, air) flows, for example, freely through the stack. The gas channel openings (which may be integrated, for example, into the frame panel, the interconnectors or the like, in the case of MSCs in the edge region of the support substrate) serve here for the supply and removal, respectively, of process gas from the sealed process gas space. EP1278259B1 describes as an example a stacked arrangement in an open structure for MSCs.

It is essential for the function of the stack that the different process gas spaces are reliably separated from one another in a gas-tight manner, and that this gas-tight separation is maintained even under mechanical load and in the cyclic temperature fluctuations that occur during operation. In particular during the manufacture of the stack, high-pressure loads occur in the edge region when the modules are compressed against one another, and these loads can lead to deflection and cracking situations at the weld seam, thereby jeopardizing the gastight state.

It is important for the efficiency of the electrochemical module that the process gases flow uniformly over the electrochemically active layer and that the formed reaction gases are removed uniformly in each case. The pressure drop is preferably no greater than a small one. Although the different electrochemical modules in the stack are fed in the vertical direction through the respective channel structures, the feeding in the horizontal direction in the electrochemical modules is done through distribution structures, which are usually integrated into the interconnectors. The interconnector, which also has the function of electrically contacting adjacent electrochemical cells, has gas-conducting structures on both sides for this purpose, and these structures may have, for example, a handle-shaped, rib-shaped or wave-shaped design. For many applications, the interconnectors are formed by suitably shaped sheet metal parts, similar to the other components of the stack, in which they may be extremely thin for weight optimization purposes. In the case of stack joining or operation, in particular in the case of mechanical stresses of this type occurring at the edge regions, such a thin construction can easily lead to deformation situations and thus to extreme deterioration in the necessary gas-tight conditions.

Disclosure of Invention

It is therefore an object of the present invention to provide an electrochemical module and a molded part for use in a process gas space of an electrochemical module, which ensure a gas-tight state of the process gas space of the electrochemical module during long-term use and even under mechanical stress and temperature fluctuations, in a cost-effective manner. Furthermore, the advance of electrochemical modules is remarkable by the advantageous gas-conducting properties; in other words, the aim is to achieve an extremely uniform, small pressure drop of the process gas in the process gas space, so that the distribution of the process gas over the flat electrochemical cell is as uniform as possible.

This object is achieved by a molded part according to claim 1, a use of a molded part according to claim 12 and an electrochemical module according to claim 13. Advantageous developments are set out in the dependent claims.

The inventive molded part is used in electrochemical modules which can be used as high-temperature fuel cells or Solid Oxide Fuel Cells (SOFCs), as solid oxide electrolysis cells (SOECs; solid oxide electrolyser cells) and as reversible solid oxide fuel cells (R-SOFCs). The basic structure of an electrochemical module of this type is characterized by an electrochemical cell having a layer structure with at least one electrochemically active layer and may also comprise a support substrate. The electrochemically active layer is herein understood to mean an anode, an electrolyte or a cathode layer or the like, and the layer structure may optionally also have further layers (e.g. made of cerium gadolinium oxide between the electrolyte and the cathode). Not all of the electrochemically active layers need be present here; alternatively, the layer structure may also have only one electrochemically active layer (e.g. anode), preferably two electrochemically active layers (e.g. anode and electrolyte), and further layers, in particular those for completing an electrochemical cell, which may not be applied until subsequently. The electrochemical cell can be designed as an electrolyte-supported cell, an anode-supported cell or a cathode-supported cell (the layer giving the cell its name has a thicker construction and has the function of bearing mechanical loads). In the case of metal substrate supported cells (MSCs), in a preferred embodiment of the invention, the layer stack is arranged on a porous plate-type metal support substrate, the preferred thickness of which is typically 170 μm to 1.5mm, more particularly 250 μm to 800 μm, in the gas permeable central region. The support substrate in this case forms part of an electrochemical cell. The layers of the layer stack are applied in a known manner, preferably by PVD (PVD: physical vapor deposition), such as for example by sputtering, and/or by thermal coating methods such as for example flame spraying or plasma spraying, and/or by wet-chemical methods such as for example screen printing, wet powder coating, etc.; two or more of these methods may also be combined in order to achieve the overall layer structure of the electrochemical cell. Typically, the anode is an electrochemically active layer proximate to a supporting substrate, while the cathode is formed on the side of the electrolyte remote from the supporting substrate. Alternatively, however, an inverted arrangement of the two electrodes is also possible.

Not only the anode (formed, for example, from a composite material consisting of nickel and zirconium dioxide sufficiently stabilized with yttrium oxide in the case of MSC), but also the cathode (formed, for example, from a perovskite having mixed electrical conductivity, such as (La, Sr) (Co, Fe) O₃Formed) has a breathable design. Formed between the anode and the cathode is a gas-tight solid electrolyte comprising a solid ceramic material made of metal oxide (e.g., yttria-sufficiently stabilized zirconia) that is conductive to oxygen ions, but not to electrons. Alternatively, the solid electrolyte is also conductive to protons, and the tongue relates to a newer generation SOFC (e.g., a metal oxide solid electrolyte, more specifically barium zirconium oxide, barium cerium oxide, lanthanum tungsten oxide, or lanthanum niobium oxide).

The electrochemical module additionally has at least one metal gas-tight housing that forms a gas-tight process gas space with the electrochemical cell. In the region of the electrochemical cell, the process gas space is delimited by a gas-tight electrolyte. On the opposite side, the process gas space is usually delimited by an interconnector, which for the purposes of the present invention is also considered to be a part of the housing. The interconnector is connected in a gas-tight manner to a gas-tight element of the electrochemical cell, optionally in combination with further housing parts, more particularly bounding frame panels or the like, which form the rest of the process gas space delimitation. In the case of MSCs, the gas-tight connection of the interconnectors is preferably done by means of soldering joints and/or soldering joints via further housing parts, examples being bounding frame panels, which in turn are connected to the support substrate in a gas-tight manner and thus form, together with the gas-tight electrolyte, a gas-tight process gas space. In the case of electrolyte-supported cells, the connection can be made by means of a sinter bond or by applying a sealant (e.g. glass solder).

"hermeticity" in connection with the present invention particularly means the rate of leakage for a sufficient amount of hermeticity based on a standard<10^-3hPa*dm³/cm²s (hPa: hectopa, dm)³: liter, cm²: square centimeter, s: seconds) (measured under air by a pressurized method using an Integra DDV instrument from dr. wiesner, rem saider, at a pressure difference dp of 100 hPa).

The housing extends beyond the area of the electrochemical cell on at least one side of the electrochemical cell and forms a process gas conducting space as a sub-space of a process gas space, which opens out to the electrochemical cell. The process gas space is thus subdivided (theoretically) into two sub-regions, into an inner region directly beneath the layer structure of the electrochemical cell and into a process gas conducting space which surrounds the inner region.

In the process gas conducting space region, there is a gas passage opening made in the housing for the supply and/or removal of process gas. The gas passage opening can be integrated, for example, into an edge region of the interconnector and a housing part, for example, a bounding frame panel.

The supply of the electrochemical cells in the inner region of the process gas space is effected by means of a distribution structure, which is preferably integrated into the interconnector. The interconnector is preferably configured as a suitably shaped sheet metal part, for example having a handle-shaped, rib-shaped or wave-shaped design.

In operation of the electrochemical module as a SOFC, a fuel (e.g. hydrogen or a conventional hydrocarbon, such as methane, natural gas, biogas, etc., optionally having been previously completely or partially reformed) is supplied to the anode via the distribution structure of the gas passage openings and the interconnectors, and this fuel is catalytically oxidized there, giving off electrons. The electrons are conducted out of the fuel cell and towards the cathode via a current-consuming element. At the cathode, an oxidant (e.g., oxygen or air) is reduced by receiving electrons. The electrical circuit is closed by the flow of oxygen ions formed at the cathode to the anode via the electrolyte (in the case of an electrolyte that is conductive to oxygen ions), and reacts with the fuel at the respective interfaces.

In operation of the electrochemical module as a Solid Oxide Electrolysis Cell (SOEC), the redox reaction is driven using an electric current, for example converting water into hydrogen and oxygen. The structure of the SOEC basically corresponds to that of the SOFC described above, and has a role of switching the cathode and the anode. Reversible solid oxide fuel cells (R-SOFCs) can be operated as SOECs or as SOFCs.

According to the invention, a molded part is provided which is designed as a separate component from the electrochemical cell and the housing. The molded parts are produced by powder metallurgy and are therefore porous or at least sectionally porous if post-treated by, for example, compression or local melting at the edges and/or on the surface. By using porous molded parts, a decisive weight saving can be produced in relation to solid parts, while at the same time comparable mechanical properties are obtained. The moulding is preferably flat and has a flat body with a main extent plane. According to the invention, the molded part is adapted to be arranged in a process gas conducting space; in other words, its shape is adapted to the interior of the process gas conducting space. In operation of the electrochemical module, the molding is arranged in the process gas conducting space, advantageously completely in the process gas conducting space, i.e. directly underneath the layer structure of the electrochemical cell completely in the process gas space outside the region.

The molding is advantageously arranged with its top side against the upper housing part of the process gas conducting space and with its bottom side against the lower housing part of the process gas conducting space. The thickness of the molding thus corresponds here to the height within the space of the process gas conducting space. The upper and lower housing walls are thus supported in the region of the process gas conducting space in the stacking direction.

The use of such a molding for an electrochemical module is advantageous in many respects.

As an important task, the molding fulfills a mechanical support function. As mentioned above, the flat moulding is a spacer and acts as a support element which prevents the edge region of the housing from being compressed under an applied compression pressure. The molding is thus able to accommodate mechanical loads in the vertical direction (in the stacking direction of the electrochemical modules) that occur during stacking and during subsequent compression of the individual modules to form a stack and to transfer these loads to adjacent modules.

The molding furthermore produces a mechanical reinforcement in the edge region of the electrochemical module. Due to the flat design of the molding, the flexural and torsional rigidity of the housing edge region is significantly increased and the housing edge region is thus protected against deflection or other deformation. As a result, additional stresses on welds or other joining points, such as welded or sintered joining points between individual housing parts and/or electrochemical cells, which in practice often represent weak points in the gas-tight state, can be avoided in the edge regions of the module.

In addition to these mechanical functions, the molded part is advantageously developed for improving the guidance of gases in the process gas conducting space. In order to optimize the guidance of the gas, gas guiding structures can be designed in the molding element to convey the gas flowing through the gas channel openings into the inner region of the process gas space to the gas guiding structures of the interconnectors and respectively to guide the gas flowing out of the inner region of the process gas space to the gas channel openings, which are led out. The gas guiding structure can be designed differently depending on whether the molded part fulfills the function of a gas distributor or a gas collector.

In a preferred embodiment, a continuous gas channel opening is integrated into the molding. The molding is oriented in the electrochemical module in such a way that the gas passage openings of the molding open into the gas passage openings of the process gas conducting space (housing) and form vertical continuous gas passages in the stack. In order to enable gas to flow to the electrochemical cell, the molding is gas-permeable in at least one direction from the gas channel opening up to the plane of the main extent of the side facing the inner process gas space. For this purpose, the molding may generally or at least in this direction have an open continuous porosity. In order to optimize the gas flow, the gas permeability (porosity) of the molded part can be varied spatially and can therefore be adjusted by means of, for example, porosity grading or local differences in the compactability of the molded part (for example as a result of non-uniform compression).

Alternatively or additionally, the moulded piece may have at least one passage along the main extent plane, thereby allowing even more direct manipulation of the gas, and a higher gas throughput rate. For better gas distribution and higher gas throughput, a plurality of channels is advantageously provided. The channel or channels are preferably superficially formed and may be introduced into the surface of the moulded article by means of, for example, grinding, pressing or rolling with a corresponding structure. For the purposes of this specification, a molded article having closed porosity and a shallow channel structure (which extends upwardly from the gas channel opening to the side edges) porosity is also considered to be gas permeable from the gas channel opening up to the side edges. It is also conceivable that the channel or channels extend at least in sections over the entire thickness of the molding and that the channels are therefore not formed only superficially. A high gas passage rate is advantageous in the case of this embodiment, but care must be taken that the moulded piece remains as a single piece and does not separate. To prevent this, the channels extending through the thickness undergo a transition over their travel to a shallow channel structure or porous structure.

To improve the flow characteristics, the shape of the channel can be optimized by various solutions:

in a preferred embodiment, the channel or channels extend continuously from the gas channel opening up to the side of the molded part facing the inner process gas space. In this way, a high gas throughput and a low pressure drop can be achieved.

According to another embodiment, the channel or channels are provided in the region of the gas channel opening extending radially or substantially radially outwards from the gas channel opening. Radial here means the local tangent of the channel extending into the gas channel opening through the center point of the gas channel opening (in the case of a non-circular gas channel opening the geometric midpoint) in the area of the channel opening. Substantially radial means that the degree of deviation from positive radial is a maximum of +/-15 deg..

In order to obtain a uniform flow in the interior of the process gas space to or from the interconnector distribution structure, the channels may open parallel or substantially parallel to each other in the side facing the inner process gas space. Parallel to each other means that the local tangents of the different channels, at the side edges, run parallel to each other, or if they are substantially parallel to each other, the angles differ by no more than +/-10 deg.. On said side edges, the individual channels are preferably equally spaced from each other and evenly distributed over said side edges.

In an advantageous embodiment, a further measure of the otherwise uniform distribution and/or removal of the process gas, in the case of a plurality of channels, provides that the cross-sectional area of the channels increases proportionally to the channel length. Thus, a larger pressure drop over a longer channel length is compensated for by a larger channel cross-sectional area.

According to an advantageous development of the flow optimization, the plurality of channels extends in a star shape away from the gas channel opening and opens into the side facing the inner process gas space. The channels, which branch off from the gas channel opening initially into a direction facing away from the inner process gas space, are redirected in this case in an arc to the side which points in the direction of the inner process gas space.

Advantageously, the molding has a plurality of gas passage openings, from which the gas guide structures branch off in each case to the side of the molding, the edge facing the inner process gas space. This enables an efficient and uniform supply to the inner process gas space.

The porous molded part can be compressed in a gas-tight manner against the remaining side regions, which in the arrangement of the electrochemical cells do not face the inner process gas space, since no gas flow is required in these directions during operation of the electrochemical module.

The molded part according to the invention is produced separately from the remaining components of the electrochemical module and is preferably produced by powder metallurgy. The molded part is preferably of monolithic design, i.e. manufactured from a single piece, which means that it does not comprise a plurality of parts connected to each other, even possibly by fusion bonding (e.g. welding, soldering, etc.). The microstructure of the molded article is evident from the production of the monolithic piece by powder metallurgy. Acting as starting material for the production of the moulded part is a metal-containing powder, preferably a corrosion-stable alloy powder, e.g. a powder such as a material combination based on Cr (chromium) and/or Fe (iron), which means that Cr and Fe are at least 50% by weight in total, preferably at least 80% by weight in total, more preferably at least 90% by weight in total. The molded part consists in this case of a ferritic alloy. The moldings are preferably produced by powder metallurgy in a known manner by compressing the starting powder, optionally with the addition of an organic binder, and subsequently sintering.

If the moulding is used for MSCs, the moulding preferably consists of the same material as the support substrate of the MSCs. This is advantageous because in this case the thermal expansion is the same and there are no temperature induced stresses.

The separate construction and therefore the separate fabrication of the molded part from the other active elements of the electrochemical cell (including the metal substrate in the case of MSC) has many advantages. First, it provides flexibility and the respective components can be optimized independently of each other for specific needs by, for example, establishing different porosities. Secondly, the production of the electrochemical cell is simplified and more economical to manufacture, and therefore the cell is less complex, since there is also no need to consider gas distribution structures at the edges. Thirdly, it also brings its advantages to the production of the molded part, since the molded part (unlike the metal substrate of MSC, which is additionally coated with the electrochemically active layer after the sintering operation) does not need to be subjected to a thermal post-treatment. The molded part can thus be produced with high end profile accuracy.

As mentioned above, the inventive molded part can be used in electrochemical modules, in particular MSCs, as described in EP2174371B 1. In a preferred embodiment, the electrochemical module has moldings, each of which is designed differently for the supply and removal of process gases. In this case, the moldings may differ, for example, in the materials used, their shape, the porosity, the shape of the gas-guiding structures formed, for example channel structures, etc. For example to prevent back diffusion, the porosity of the moulded piece for removing gas may be lower than the porosity of the moulded piece for supplying gas.

The molded part is preferably fixed in the electrochemical module by means of a fusion joint, for example by spot welding on the housing. It may be noted that even in this case, when the molding is mounted in a module, it is fusion-bonded into another component of the electrochemical cell, which is considered to be the object of the present invention as a constituent component formed separately from the electrochemical cell.

In an embodiment of the above-described variant, the porous molding has a mechanical support function and serves to improve the flow of gas in the process gas conducting space. In an advantageous development, the porous molded part is additionally functionalized on its surface to improve its catalytic and/or reactive properties for the treatment of process gases; in other words, by appropriately functionalizing the surface, the process gas can be treated (process gas treatment on the reactant side and/or post-treatment on the product side). In the case of functionalization with catalytic and/or reactive properties, the use of porous moldings is advantageous, since the surface which comes into contact with the process gas as it flows through is significantly larger and, correspondingly, in the case of porous components, the reaction is more likely to occur than in the case of solid components.

In SOFC use, for example, the process gas can be additionally reformed on the reactant side by means of a functionalized moulding (which means that the carbon-containing fuel gas is converted into a synthesis gas comprising a mixture of carbon monoxide and hydrogen) and/or can be cleaned to remove impurities such as sulphur or chlorine. On the product side, the appropriately functionalized moldings can be used, for example, for cleaning to remove volatile chromium.

The functionalization of porous molded parts can be carried out by incorporating into the material of the molded part and/or applying as a surface coating such substances for catalytic and/or reactive action with the process gas. The catalytic and/or reactive substances can thus be mixed into the actual starting powder to produce sintered moldings ("alloying addition") and/or can be applied to the surface of the moldings by a coating procedure and have open pores after the sintering operation. Such coating procedures can be carried out by conventional methods known to the person skilled in the art, for example by means of different deposition methods from the vapour phase (physical vapour deposition, chemical vapour deposition), by dip coating, in which the component is impregnated or infiltrated with a melt containing the respective functional material, or by means of methods of applying suspensions or pastes, in particular for ceramic materials. For surface enlargement it is advantageous if the porous surface structure remains during the coating procedure, i.e. the porous surface is not covered by the top layer, but mainly only the inner surface of the porous structure is coated.

When using molded parts produced by powder metallurgy from iron and/or chromium based alloys, it has been found suitable to functionalize with: the following are used for treating the process gas on the reactant side:

for catalytic reforming of fuel gas: nickel, platinum, palladium and oxides of these metals such as NiO;

for cleaning reactant gases to remove sulfur and/or chlorine: nickel, cobalt, chromium, scandium, and/or cerium;

for purifying reactant gases, involving oxygen: chromium, copper and/or titanium, and titanium also deals with the retention effect with respect to carbon.

For the working-up of the process gas on the product side the following are used:

getter structure for purification with respect to volatile chromium ions: oxide ceramics such as, for example, Cu-Ni-Mn spinel;

for purifying the product gas, involving oxygen and preventing back diffusion: titanium, copper or spinel compounds with an insufficient stoichiometric ratio.

Drawings

Further advantages of the invention will become apparent from the following description of exemplary embodiments and with reference to the accompanying drawings, wherein the dimensional proportions are not always given in exact proportions for the purpose of illustrating the invention. In different figures, the same reference numerals are used for the same components.

In the drawings:

FIG. 1 a: a molded article of a first embodiment is shown in perspective view, for use in an electrochemical module;

FIG. 1 b: the molded part of fig. 1a is shown in plan view; and

FIG. 1 c: the molded part of fig. 1a is shown in a side view;

FIG. 2 a: a stack with three electrochemical modules according to the prior art, without the molding according to the invention, is shown in a sectional view;

FIG. 2 b: a stack with three electrochemical modules, each having a molding according to fig. 1a, is shown in a sectional view;

FIG. 2 c: the electrochemical module of fig. 2b is shown in an exploded view, with the molded part according to fig. 1a (it should be noted here that the electrochemical module of fig. 2c is shown turned over on its head for better viewing of the channels, compared to the modules of fig. 2a and 2 b);

FIG. 3 a: a molded article of a second embodiment for an electrochemical module is shown in a perspective view; and

FIG. 3 b: the molded part of fig. 3a is shown in plan view.

Detailed Description

Fig. 1a shows a molded part (10) of a first embodiment in a perspective view, which is used for an electrochemical module (20). The arrangement of the molded part (10) in the electrochemical module (20) is shown in fig. 2b and 2 c. Fig. 1b shows the molding (10) in plan view and it is shown in fig. 1c in side view from the side (a), which in the arrangement of the electrochemical modules (20) faces the interior of the process gas space. The molded part (10) has been produced by powder metallurgy and is therefore porous. The molding is flat and has a flat body with a main extent plane. It has a plurality of gas passage openings (11), which in the variant shown have three central gas passage openings (11), through which the process gases are supplied and removed in the operation of the electrochemical module, respectively. The channels (12) extend in a star shape from each gas channel opening up to the side (a) of the moulding, which in the arrangement of the electrochemical modules faces the inner process gas space of the electrochemical module. The channels, which initially branch off from the gas channel openings (11) in a direction away from the inner process gas space, are here redirected in an arc towards the side (a) in the direction of the inner process gas space. The individual channels (12) extend continuously from the gas channel opening to the side edge (A), whereby an efficient gas guidance and a low pressure drop in the process gas conducting space can be achieved.

Furthermore, the moulded part (10) has an open structure which is gas-permeable in the direction of the side edges (a) from the gas passage openings (11) (in other words, an exchange of gas between individual adjacent holes is possible). On the other side, the molded part is pressed together (13) and is therefore gas-impermeable in these directions.

In operation of the electrochemical module, process gas flows from the gas channel openings (11) through the channels (12) and the holes to the side (a) of the molded part, from where it flows into the inner process gas space. The gas flow may also be in the opposite direction.

The number and geometry of the channels is optimized to maximize the uniformity of the supply to the inner process gas space. For this purpose, at the side edges (a), the spacing of adjacent channels is substantially equal, and so when they are spread apart, the channels are evenly distributed over the side edges. Furthermore, in this exemplary embodiment, the channels at the side edges (a) run out at approximately right angles; in this region, the channels extend substantially partially parallel to one another.

As can be seen in fig. 1c, the channels are manufactured superficially and their cross-sectional area is varied. The cross-sectional area of the channel is substantially constant over its length, but is selected to be larger over the length of the channel from the gas channel opening (11) up to the side (a). This is also a measure to achieve a maximum of flow uniformity in the distribution structure to and removal from the interconnectors in the interior of the process gas space.

Fig. 2a shows a stack with three electrochemical modules according to the prior art without the inventive molding. The arrangement of the molded part in the electrochemical module (20) is shown in fig. 2b and 2 c. Fig. 2a and 2b each show in a schematic way a cross section through a stack (30) with three electrochemical modules (20) stacked on top of each other. The electrochemical modules (20) each have an electrochemical cell (21), which is composed of a porous, metallic support substrate (22), which has been produced by a powder metallurgy process, and which has a layer structure (23) having at least one electrochemically active layer applied to a gas-permeable region of the substrate (22) in the gas-permeable region. The support substrates (22) with the layer structure (23) are pressed together at the edges in a gas-tight manner and have a plate-type substrate structure, which in variant embodiments serves to enlarge the surface area and can also have a local curvature over a smaller length, for example a wave-shaped design. Located on the side of the support substrate (22) which is opposite the layer structure described here is in each case an interconnector (24) which has a rib structure (24a) in the region in which it bears on the support substrate (22). The longitudinal direction of the rib structure extends in the cross-sectional plane of fig. 2a and 2 b. An interconnector (24) extends beyond the area of the electrochemical cells (21) and bears at its outer edges on frame panels (25) bounding the electrochemical cells. A boundary frame panel (25) is joined to the inner edge of the electrochemical cells (21) in a gas-tight manner via a boundary welded connection and to the outer edge of the interconnector (24) in a gas-tight manner. The frame panel (25) and the interconnector (24) thus form part of a metal gas-tight housing, which delimits a gas-tight process gas space (26) with the electrochemical cells (21). The process gas conducting space (27) is a subspace of the process gas space (26) and extends in a region outside the region of the electrochemical cell (21) and is open in the direction of the electrochemical cell (21). In the region of the process gas conducting space there is a gas channel opening (28) (frame panel and interconnector) formed in the housing for supplying and/or removing process gas (not shown in fig. 2a and 2b, since the cross-section is taken from the side of the gas channel opening). The housing (28) of the moulding and the gas passage opening (11) are aligned with each other. The gas conduction within the stack takes place in the vertical direction (stacking direction of the stack (B)) by means of corresponding channel structures, which are formed in the region of the gas channel openings, typically by means of separate inlays (29), sealing strips and by controlled application of a sealant, for example glass solder. The channel structure thus seals the process gas conducting spaces connecting adjacent electrochemical modules in the vertical direction.

While fig. 2a shows the prior art without a molding, fig. 2b and 2c show the arrangement of the molding according to fig. 1a in the process gas conducting space (27) of the electrochemical module (20). It should be noted that in fig. 2c, the electrochemical module is shown turned around at its head for better viewing of the channels (12) than the module of fig. 2a and 2 b. The shape of the molding is adapted to the interior of the process gas conducting space. The molding is loaded by its top side against a frame panel (25), which is the upper boundary of the process gas conducting space, and by its bottom side against an interconnector (24), which is the lower boundary of the process gas conducting space. A flat contact is advantageous in each case at its top side and/or at its bottom side. Its thickness thus corresponds to the internal height of the process gas conducting space (27). The superficially formed channel (12) is located on the underside of the moulding (10) (in figure 2c the moulding is shown turned at its head). The molded part has an important mechanical function also in terms of the gas guiding function in the process gas conducting space. It serves to support the housing in the stacking direction of the stack (B) against compression in the edge region of the housing when a compressive pressure is applied. Furthermore, because of the flat configuration of the molding, it is possible to decisively increase the flexural and torsional rigidity of the housing edge region, which consists of the thin frame panel (25) and the thin interconnectors (24), and thus to reduce the risk of the weld breaking under mechanical load. In an advantageous variant embodiment, the molding is spot-welded to the housing and is thus fixed. The molded parts (10, 10') for supplying and removing the process gas are preferably different. Their properties (material, shape, porosity, geometry of the channel structure, etc.) can be optimized independently of one another for their intended use.

Fig. 3a shows a molded part of a further variant embodiment in a schematic perspective view and fig. 3b in a plan view. In this variant embodiment, the individual gas passage openings (11) of the molded part are in communication with one another via further passages. This channel structure constitutes a further gas balance.