FUNCTIONALIZED, POROUS GAS CONDUCTION PART FOR ELECTROCHEMICAL MODULE

Abstract

A porous or at least sectionally porous gas conduction part is provided for an electrochemical module. The electrochemical module has at least one electrochemical cell unit having a layer construction with at least one electrochemically active layer, and a metallic, gastight housing which forms a gastight process gas space with the electrochemical cell unit. The housing extends on at least one side beyond the region of the electrochemical cell unit, and forms a process gas conduction space open to the electrochemical cell unit, and in the region of the process gas conduction space has at least one gas passage opening for the supply and/or removal of the process gases. The gas conduction part here is adapted for arrangement within the process gas conduction space and its surface is functionalized for interaction with the process gas.

Claims

1-20. (canceled)

21. A porous or at least sectionally porous gas conduction part for an electrochemical module, the electrochemical module containing at least one electrochemical cell unit having a layer construction with at least one electrochemically active layer, and a metallic, gastight housing forming a gastight process gas space with the electrochemical cell unit, wherein on at least one side the metallic, gastight housing extending beyond a region of the electrochemical cell unit, and forms a process gas conduction space open to the electrochemical cell unit, and in a region of the process gas conduction space having at least one gas passage opening for a supply and/or removal of process gases, the gas conduction part comprising: a gas conduction part body being adapted for arrangement within the process gas conduction space and a surface of the gas conduction part body being functionalized for interaction with a process gas.

22. The gas conduction part according to claim 21, wherein said gas conduction part body is configured as a separate component from the electrochemical cell unit.

23. The gas conduction part according to claim 21, wherein said gas conduction part body is adapted for supporting the metallic, gastight housing on both sides along a stack direction of the electrochemical module.

24. A porous or at least sectionally porous gas conduction part for an electrochemical module, the electrochemical module containing at least one electrochemical cell unit having a layer construction with at least one electrochemically active layer, and a metallic, gastight housing forming a gastight process gas space with the electrochemical cell unit, wherein on at least one side the metallic, gastight housing extending beyond a region of the electrochemical cell unit and forming a process gas conduction space open to the electrochemical cell unit, and in a region of the process gas conduction space having at least one gas passage opening formed therein for a supply and/or removal of process gases, the gas conduction part comprising: a gas conduction part body configured as a housing part of the process gas conduction space and a surface of said gas conduction part body that faces a process gas conduction interior is functionalized for interaction with a process gas.

25. The gas conduction part according to claim 24, wherein said gas conduction part body is formed integrally with a metallic support substrate of the electrochemical cell unit.

26. The gas conduction part according to claim 24, wherein said gas conduction part body is functionalized for catalytic reforming a reactant gas.

27. The gas conduction part according to claim 26, wherein a functionalization for the catalytic reforming is accomplished by introduction of nickel, platinum and/or palladium and/or oxides of these metals.

28. The gas conduction part according to claim 24, wherein said gas conduction part body is functionalized for purifying a reactant gas.

29. The gas conduction part according to claim 28, wherein a functionalization for purifying the reactant gas with respect to sulfur and/or chlorine is accomplished by introduction of nickel, cobalt, chromium and/or cerium.

30. The gas conduction part according to claim 28, wherein a functionalization for purifying the reactant gas with respect to oxygen is accomplished by introduction of chromium, copper and/or titanium.

31. The gas conduction part according to claim 28, wherein a functionalization for purifying the reactant gas with respect to carbon is accomplished by introduction of titanium.

32. The gas conduction part according to claim 24, wherein said gas conduction part body is functionalized for purifying a product gas.

33. The gas conduction part according to claim 32, wherein a functionalization for purifying the product gas with respect to chromium is accomplished by introduction of oxidic ceramics.

34. The gas conduction part according to claim 32, wherein a functionalization for purification with respect to oxygen is accomplished by introduction of Ti and/or Cu or sub-stoichiometric spinel compounds.

35. The gas conduction part according to claim 27, wherein the introduction is accomplished by alloying or by a coating procedure.

36. The gas conduction part according to claim 24, wherein said gas conduction part body has a base material being a ferritic alloy produced by powder metallurgy and based on iron and/or chromium.

37. The gas conduction part according to claim 24, wherein said gas conduction part body has at least one gas guide structure.

38. An electrochemical module, comprising: a substantially plate-shaped electrochemical cell unit having a layer construction with at least one electrochemically active layer; a metallic, gastight housing forming a gastight process gas space with said electrochemical cell unit, wherein on at least one side said metallic, gastight housing extending beyond a region of said electrochemical cell unit, and said metallic, gastight housing forming a process gas conduction space open to said electrochemical cell unit, said metallic, gastight housing having gas passage openings formed therein in a region of said process gas conduction space for a supply and/or removal of process gases; at least one of: at least one gas conduction part disposed within said process gas conduction space in a region of said gas passage openings, said at least one gas conduction part having a surface functionalized for interaction with a process gas, said at least one gas conduction part disposed and serving to support said metallic, gastight housing along a stack direction of the electrochemical module; or said metallic, gastight housing having said process gas conduction space is formed at least sectionally by at least one gas conduction part, said at least one gas conduction part having at least a surface facing a process gas conduction interior and being functionalized for interaction with a process gas.

39. The electrochemical module according to claim 38, wherein said metallic, gastight housing containing at least two sides that extend beyond a region of said electrochemical cell unit, and forming a first process gas conduction space having at least one gas entry opening for a reactant gas, to which at least one first said gas conduction part is assigned, and a second process gas conduction space having at least one gas exit opening for a product gas, to which at least one second said gas conduction part is assigned, where a functionalization of said first gas conduction part assigned to said first process gas conduction space differs from a functionalization of said second gas conduction part assigned to said second process gas conduction space.

40. The electrochemical module according to claim 39, wherein said first gas conduction part is functionalized for treatment of a reactant gas and/or said second gas conduction part is functionalized for post-treatment of the product gas.

Description

[0034] Of the figures:

[0035] FIG. 1a: shows a first embodiment of a functionalized gas conduction part for use in an electrochemical module, in perspective view;

[0036] FIG. 1b: shows the gas conduction part of FIG. 1a in plan view; and

[0037] FIG. 1c: shows the gas conduction part of FIG. 1 a in a side view;

[0038] FIG. 2: shows a first embodiment of the electrochemical module with a gas conduction part according, respectively, to FIG. 1a-c for the process gas conduction space, for the supply or removal of the process gases, respectively, in an exploded view (here it must be borne in mind that, in comparison to the modules in FIG. 3, the electrochemical module in FIG. 2 is shown turned on its head for improved visibility of the channels);

[0039] FIG. 3: shows a stack with three electrochemical modules as per FIG. 2, in cross section;

[0040] FIG. 4: shows a second embodiment of the electrochemical module, in an exploded view, and

[0041] FIG. 5: shows a stack with three electrochemical modules as per FIG. 4, in cross section.

[0042] FIG. 1a shows, in a perspective view, a first embodiment of the functionalized gas conduction part (10), which is configured as a separate component and is arranged in the electrochemical module, in particular in an SOFC, within the process gas conduction space. One possible arrangement in the process gas conduction space is apparent from the following FIG. 2 and FIG. 3. FIG. 1b shows the gas conduction part (10) in plan view, and it is shown in FIG. 1c in a side view from the side (A), which in the arrangement in the electrochemical module (20) is facing the interior of the process gas space. The gas conduction part (10) is produced by powder metallurgy from an Fe-based alloy with >50 wt % Fe and 15 to 35 wt % Cr. A powder having a particle size <150 m, more particularly <100 m, was selected, so that after the sintering operation the porous gas conduction part has a porosity of preferably 20 to 60%, more particularly 40 to 50%. The thinner the gas conduction part to be formed, the smaller the selected particle size. With preference an open porosity is established (i.e., with the possibility of gas exchange between individual adjacent pores). The thickness of the part is preferably in the range from 170 m to 1.5 mm, more particularly in the range from 250 m to 800 m. The flat gas conduction part has a plurality of gas passage openings (11)in the variant depicted, three central gas passage openings (11)through which the process gas is supplied and, respectively, removed in the operation of the electrochemical module. The process gas flow is additionally steered by gas guide structuresin the present exemplary embodiment, by star-shaped channels (12) which are formed superficially and extend from the gas passage openings up to the side edge (A). Channels which branch off from the gas passage opening (11) originally in a direction remote from the inner process gas space are redirected here in an arc shape to the side edge (A) in the direction of inner process gas space. At the remaining side edges (13) (apart from side edge (A)), the gas conduction part has been pressed in a gastight manner. In the operation of the electrochemical module, the process gas flows from the gas passage openings (11) through the channels (12) and through the pores to the side edge (A) of the gas conduction part, from which it flows on into the interior process gas space, which is supplied extremely uniformly by the numerous channels. When the gas conduction part is used for removing the process gases, the gas flows in the opposite direction.

[0043] For the functionalization, the surface of the gas conduction part on the side with the channels was coated in a PVD unit with a functional layer (14) <1 m in thickness. In this operation, care was taken to ensure that the porous surface structure of the gas conduction part is retained in the course of coating, i.e., the openly porous surface is not overlayered by a top coat, so that there continues to be a functionalized surface area which is large in comparison to a smooth surface. Care was also taken to ensure that, in particular, the surface of the channels over which the process gas flow passes, and which is therefore in comparatively intensive contact with the process gas, was sufficiently coated.

[0044] A plurality of gas conduction parts with different functionalization for the treatment or post-treatment of the process gases, respectively, were produced, these gas conduction parts being intended for use in an SOFC. A first exemplary embodiment of the gas conduction part was coated with Ni, and a second one with NiO. Both gas conduction parts find application in the treatment of combustion gases; the functionalized surface of both exemplary embodiments serves as a catalyst for the reforming of the combustion gas and also has a getter effect in relation to chlorine and sulfur. For the gas conduction part for the post-treatment of outgoing gas, a Ti coating was selected which filters Cr ions from the flow of outgoing gas.

[0045] FIG. 2 and FIG. 3 illustrate the arrangement of the gas conduction parts (10,10) in the electrochemical module. FIG. 2 shows, in an exploded view, an electrochemical module (20) having correspondingly functionalized gas conduction parts (10, 10); FIG. 3, in a cross-sectional view, represents a stack (30) having three electrochemical modules (20) stacked on top of one another. It should be borne in mind that in FIG. 2, in comparison to the modules in FIG. 3, the electrochemical module is shown turned on its head for better visibility of the channels (12). The electrochemical modules (20) each have an electrochemical cell unit (21) which consists of a porous, metallic support substrate (22) which has been produced by powder metallurgy, with a layer construction (23) with at least one electrochemically active layer applied on this substrate (22) in a gas-permeable region. The support substrate (22) with the layer construction (23) is pressed together in a gastight manner at the edge and has a plate-shaped base structure which in variant embodiments, for enlargement of surface area, may also have local curvaturefor example, a wave-shaped designover a smaller length scale. Located on the side of the support substrate (22) that is opposite the layer construction there is in each case an interconnector (24), which in the region where it bears against the support substrate (22) has a rib structure (24a). The longitudinal direction of the rib structure runs here in the cross-sectional plane in FIG. 3. The interconnector (24) extends at two opposite sides beyond the region of the electrochemical cell unit (21) and bears at its outer edge against a frame panel (25) circumscribing the electrochemical cell unit. The circumscriptive frame panel (25) is joined in gastight fashion to the electrochemical cell unit (21) at the inner edge, and is joined in gastight fashion to the interconnector (24) at the outer edge, via a circumscriptive welded connection. The frame panel (25) and the interconnector (24) thus form a constituent of a metallic, gastight housing which, with the electrochemical cell unit (21), delimits a gastight process gas space (26). The process gas space (26) is subdivided (conceptually) into two opposite sub-spacesthe two process gas conduction spaces (27, 27)with the sub-spaces each extending over a region outside the region of the electrochemical cell unit (21) and being open in the direction of electrochemical cell unit (21). In this arrangement, a first process gas conduction space (27) serves, via corresponding gas entry openings (28) in the housing (frame panel and interconnector), for the supply of the process gases, whereas the opposite process gas conduction space (27) serves, via corresponding gas exit openings (28), for removal of the process gases (the gas passage openings are not shown in FIG. 3, since the section is located to the side of the gas passage openings). The conducting of gas within the stack takes place in a vertical direction (stack direction of the stack (B)) by means of corresponding channel structures, which are formed in the region of the gas passage openings customarily by means of separate inlays (29), seals, and also by controlled application of sealant (e.g. glass solder).

[0046] Arranged within the process gas conduction space (27) for supply is a gas conduction part (10) whose surface is functionalized for the treatment of the reactant gas (reforming, purification). The gas conduction part (10) functionalized for the post-treatment of the product gases is arranged within the opposite process gas conduction space (27) for the removal of the product gases. The gas conduction parts (10, 10) used for supply and removal therefore preferably have different functionalization. The gas conduction parts may of course also differ in other properties (base material, shape, porosity, geometry of channels, etc) and may be optimized independently of one another for their intended use.

[0047] The gas conduction parts (10,10) are preferably configured as a support element in the stack direction (B) of the electrochemical modules. For this purpose, the shape of the gas conduction part is adapted in each case to the interior of the respective process gas conduction space. Each of the gas conduction parts (10, 10) bears by its top side against the frame panel (25), the upper boundary of the respective process gas conduction space (27, 27), and by its bottom side against the interconnector (24), the lower boundary of the respective process gas conduction space. A flat contact is advantageous in particular, at the top side and/or at the bottom side of the respective gas conduction part. The thickness of the gas conduction part therefore corresponds to the space internal height of the respective process gas conduction space (27,27). The channels (12) formed superficially are located on the underside of the gas conduction parts (10,10). Because of the flat architecture of the gas conduction parts, the flexural and torsional stiffness of the housing edge region, which consists of a thin frame panel (25) and a thin interconnector (24), is decisively increased and hence the risk of cracking in the weld seams under mechanical loading is reduced. In one advantageous variant embodiment, the functionalized gas conduction parts are spot-welded on the housing and fixed accordingly.

[0048] FIG. 4 and FIG. 5 show a second exemplary embodiment of the electrochemical module (20), in which the gas conduction parts (10,10) form part of the housing and are implemented integrally with the support substrate (22). The porous support substrate (22) is pressed in gastight manner on two opposite sides, in each case at the edge region, in each of which sides there are gas passage openings (11,11) integrated. The edge region may also be made gastight on the side facing the layer construction (23) by means of a melting operation effected, for example, by laser beam melting. These opposite edge regions of the support substrate are outside the gas-permeable region with the layer construction (23). They each represent a gas conduction part (10,10) and delimit the two process gas conduction spaces (27,27) towards the top. In the pressing procedure, optionally, gas guide structures (12) may be integrated on the underside (side facing the interior of the process gas conduction space) of the edge region of the support substrate. In the variant realized, the edge region (10) of the support substrate that is assigned to the supply of the combustion gas is coated on its underside with Ni; the edge region (10) assigned to the removal of the outgoing gas is coated on its underside with Ti. Treatment of the combustion gases and purification of the outgoing gases are achieved in a manner analogous to the exemplary embodiment from FIG. 1 to FIG. 3.

[0049] Not only for the exemplary embodiment shown in FIG. 1 to FIG. 3, with a separate gas conduction part, but also for the exemplary embodiment shown in FIG. 4 and FIG. 5, with the integrated gas conduction part, there are of course functionalizations conceivable that are other than the Ni and/or NiO and the Ti coating. For use in an SOFC, the gas conduction part may be functionalized on the reactant-gas side not only with Ni or NiO but also with Pt, Pd (and/or oxides of these two metals), Co, Cr, Sc, cerium, Cu and/or Ti. Possible functionalizations of the gas conduction part on the product side include Ti, Cu and/or oxidic ceramics, more particularly CuNiMn spinels.