JP2012216471A - Method for manufacturing fuel cell structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a fuel cell structure with excellent mass-productivity.SOLUTION: A method for manufacturing a fuel cell structure includes a structure formation step, and a removing step. In the structure formation step, a fuel cell structure that is a multi-layer film structure at least three layers, a fuel electrode layer 5, an electrolyte layer 6 and an oxidant electrode layer 7 is formed on a surface of a sacrificial member having an outer shape corresponding to a shape of a gas flow path including a suction part, plural branch parts branched from the suction part and an exhaust part converged with a downstream side of the plural branch parts. In the removing step, during and after completion of the structure formation step, the sacrificial member is removed.

Description

  The present invention relates to a method of manufacturing a fuel cell structure, and in particular, a gas flow path including an intake portion, a plurality of branch portions branched from the intake portion, and an exhaust portion where downstream ends of the plurality of branch portions merge. The present invention relates to a method for manufacturing a fuel cell structure having

  A fuel cell is most commonly a stack structure in which planar single cells are stacked with a member called a separator interposed therebetween. As a structure of the fuel cell, there is a structure in which a large number of tube-shaped single cells are arranged in addition to the above-described stack structure.

  The above unit cell typically oxidizes a solid polymer electrolyte membrane using a solid polymer ion exchange membrane, a solid oxide electrolyte membrane using yttria-stabilized zirconia (YSZ), etc., with a fuel electrode (anode). The structure is sandwiched from both sides with the agent electrode (cathode).

JP2003-297387A (summary, paragraph 0060) JP 2004-139980 (Abstract, Claim 10) Japanese Patent Laying-Open No. 2004-152771 (Summary, paragraph 0026) JP 2008-126561 A (paragraphs 0035 and 0040) JP 2008-130286 A (summary)

  In any of the structures described above, it is necessary to assemble a large number of single cells and assemble a pipe for supplying fuel gas and oxidant gas, and the structure becomes complicated. For this reason, the mass productivity is poor and the number of parts is large, so that the cost is high. Furthermore, when the seal which prevents the gas leak from a connection part is inadequate, there existed a problem that electric power generation efficiency fell by the gas leak from a connection part.

  Here, when the manufacturing method of the fuel cell disclosed in Patent Documents 1 to 5 is adopted, the mass productivity of the fuel cell is slightly improved because a sacrificial layer is used in these manufacturing methods. In order to manufacture a fuel cell having a gas flow path including an intake section, a plurality of branch sections branched from the intake section, and an exhaust section where downstream ends of the plurality of branch sections merge, Since assembly of piping and the like is necessary in addition to manufacturing, the mass productivity of the fuel cell remains poor.

  In view of the above situation, an object of the present invention is to provide a method for manufacturing a fuel cell structure excellent in mass productivity.

  In order to achieve the above object, a method of manufacturing a fuel cell structure according to the present invention includes an intake section, a plurality of branch sections branched from the intake section, and an exhaust section where downstream sides of the plurality of branch sections merge. A structure in which a fuel cell structure having a multilayer structure including at least three layers of a fuel electrode layer, an electrolyte layer, and an oxidant electrode layer is formed on the surface of a sacrificial member having an outer shape corresponding to the shape of the gas flow path. A body forming step and a removing step of removing the sacrificial member during or after the structure forming step.

  According to such a manufacturing method, the fuel cell having a complicated shape having a gas flow path including an intake portion, a plurality of branch portions branched from the intake portion, and an exhaust portion where downstream sides of the plurality of branch portions merge. Since the structure can be integrally formed without a seam, an assembling process is not required, and mass productivity is improved. Further, since a separator, a spacer, and the like, which are necessary in the conventional stack structure, are unnecessary, it is advantageous in terms of reducing the weight, size, density, and cost of the fuel cell structure.

  Further, in the structure forming step, an end of the sacrificial member corresponding to the intake portion is inserted into the intake port of the first holding member, and the exhaust portion is inserted into the exhaust port of the second holding member. After the end of the sacrificial member corresponding to is inserted and a layer that completely covers the connection boundary between the first holding member and the second holding member and the sacrificial member is formed, the removing step is executed. You may do it.

  As a result, the fuel cell structure (including those in the middle of manufacture) is connected and held to the first holding member and the second holding member, so that the fuel cell can be applied without applying excessive force to the fuel cell structure that is a thin film. The structure can be handled. The first holding member and the second holding member may have an integrated structure.

  Further, the electrolyte layer covers the entire outer surface of the fuel electrode layer or the oxidizer electrode layer formed inside the electrolyte layer, and the first holding member, the second holding member, and the electrolyte You may make it form so that the connection boundary with the said fuel electrode layer or the said oxidizing agent electrode layer formed inside a layer may be covered completely.

  Thereby, it is possible to realize a gas seal having high airtightness by the first holding member and the second holding member and the dense electrolyte layer that does not allow gas to pass therethrough. Furthermore, since piping connection with the outside can be performed at the intake port of the first holding member and the exhaust port of the second holding member that can be maintained at a relatively low temperature, gas sealing is easy and reliability can be improved.

  The removing step may be a step of removing the sacrificial member by heat treatment in the middle of the structure forming step.

  Thereby, a removal process can be simplified.

  In addition, the sacrificial member may be shaped to form a connection point between the branch portions.

  Thereby, the mechanical strength of the fuel cell structure is improved.

  According to the method for manufacturing a fuel cell structure according to the present invention, an assembling process becomes unnecessary, and mass productivity is improved.

It is a perspective view of the fuel cell structure obtained by the manufacturing method concerning one embodiment of the present invention. It is sectional drawing in the cross section A-A 'shown in FIG. 1 of the fuel cell structure obtained by the manufacturing method which concerns on one Embodiment of this invention. FIG. 3 is a cross-sectional view taken along a cross-section A-A ′ shown in FIG. 2 when the first step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. It is sectional drawing in the cross section A-A 'shown in FIG. 2 at the time of the 2nd process completion of the fuel cell structure obtained by the manufacturing method which concerns on one Embodiment of this invention. FIG. 5 is a cross-sectional view taken along a cross-section A-A ′ shown in FIG. 2 when a third step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. It is sectional drawing in the cross section A-A 'shown in FIG. 2 at the time of the 4th process completion of the fuel cell structure obtained by the manufacturing method which concerns on one Embodiment of this invention. It is sectional drawing in the cross section A-A 'shown in FIG. 2 in the time of completion of the 5th process of the fuel cell structure obtained by the manufacturing method which concerns on one Embodiment of this invention. It is a figure which shows the modification of a sacrificial member. It is a perspective view of the fuel cell structure when the shape of the holding member is changed. FIG. 10 is a cross-sectional view of the fuel cell structure shown in FIG. 9 taken along a cross-section A-A ′ shown in FIG. 9. It is sectional drawing of the several fuel cell structure connected in series.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described later.

  FIG. 1 is a perspective view of a fuel cell structure obtained by a manufacturing method according to an embodiment of the present invention. However, the current collection pattern is not shown in FIG. FIG. 2 is a cross-sectional view of the fuel cell structure obtained by the manufacturing method according to one embodiment of the present invention, taken along the section A-A ′ shown in FIG. 1.

  A fuel cell structure 4 made of a multilayer film (hereinafter referred to as SOFC film) constituting a SOFC (Solid Oxide Fuel Cell) is connected to a ceramic holding member 3 having an intake port 1 and an exhaust port 2. .

  The fuel cell structure 4 has a gas flow path including an intake portion, a plurality of branch portions branched from the intake portion, and an exhaust portion where downstream ends of the plurality of branch portions merge. The upstream end of the intake portion is connected to the intake port 1 of the holding member 3, and the exhaust port 2 of the holding member 3 is connected to the downstream end of the exhaust portion. As described above, by providing a plurality of branch portions whose flow paths are narrower than those of the intake portion and the exhaust portion, a sufficient reaction area in the fuel cell can be ensured in a relatively small space.

  The SOFC film is a three-layer film in which a fuel electrode layer (anode layer) 5, a solid oxide electrolyte layer 6, and an oxidant electrode layer (cathode layer) 7 are laminated in this order from the inside. The solid oxide electrolyte layer 6 has a dense structure because it is necessary to pass only oxygen ions without passing gas. For example, a known lanthanum galade electrolyte (LSGM), yttria stabilized zirconia (YSZ), ceria An electrolyte (GDC) or the like can be used. On the other hand, the fuel electrode layer 5 and the oxidant electrode layer 7 are porous because the reaction gas needs to pass therethrough. For the fuel electrode layer 5, for example, NiO-LSGM, NiO-YSZ, NiO-GDC or the like is used. For the oxidant electrode layer 7, for example, lanthanum strontium manganite (LSM), lanthanum strontium cobaltite (LSC), samarium strontium cobaltite (SSC) or the like is used. Each layer has a thickness of several μm to several tens of μm, but in order to ensure the strength as a structure, one of the three layers (for example, the fuel electrode layer 5) is made thicker, and the thicker layer is formed. It is good also as a support body layer.

  A fuel gas (for example, hydrogen gas) is introduced from the intake port 1 of the holding member 3 into a gas flow path (on the fuel electrode layer 5 side) in the fuel cell structure 4, and an oxidant gas (for example, oxygen or air) is introduced into the fuel cell structure. Electric power is generated by supplying it to the periphery of the body 4 (oxidant electrode 7 side). And the gas containing the water (water vapor | steam) produced | generated in the case of electric power generation is discharged | emitted from the exhaust port 2 of the holding member 3 as exhaust gas.

  An anode current collection pattern 8 and a cathode current collection pattern 9 are formed on the holding member 3, and an anode current collection pattern 8 and a cathode current collection pattern 9 are similarly formed on the fuel cell structure 4. The anode current collection pattern 8 and the cathode current collection pattern 9 are electrically connected to the anode current collection pattern 8 of the holding member 3 and the anode current collection pattern 8 of the fuel cell structure 4. The pattern layout is such that the electricity pattern 9 and the cathode current collection pattern 9 of the fuel cell structure 4 are electrically connected. The anode current collection pattern 8 and the cathode current collection pattern 9 are each made of a conductive material.

  Then, the manufacturing method which concerns on one Embodiment of this invention is demonstrated with reference to FIGS. FIG. 3 is a cross-sectional view taken along a cross-section A-A ′ shown in FIG. 2 when the first step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. FIG. 4 is a cross-sectional view taken along a cross-section A-A ′ shown in FIG. 2 when the second step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. FIG. 5 is a cross-sectional view taken along the section A-A ′ shown in FIG. 2 when the third step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. 6 is a cross-sectional view taken along a cross-section A-A ′ shown in FIG. 2 when the fourth step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed. FIG. 7 is a cross-sectional view taken along the section A-A ′ shown in FIG. 2 when the fifth step of the fuel cell structure obtained by the manufacturing method according to the embodiment of the present invention is completed.

  As the holding member 3, for example, a molded body molded from an unfired ceramic material is prepared. The molded body has an intake port 1 and an exhaust port 2 and further has a fixing portion for installing a structure made up of the holding member 3 and the fuel cell structure 4 in a storage container or the like. For example, if a slit-like rail corresponding to the longitudinal side surface portion of the plate-shaped portion (see FIG. 1) of the holding member 3 is provided in the container, the longitudinal side surface portion of the plate-shaped portion is the fixed portion. It becomes. Further, for example, if a screw hole for fixing the structure is formed in the storage container, a through hole is provided at a position corresponding to the screw hole of the holding member 3, and the through hole is connected to the fixing portion. do it.

  Further, as the sacrificial member 10, for example, a molded product molded with a thermoplastic resin is prepared. The molded product has an outer shape corresponding to the shape of the gas flow path of the fuel cell structure 4.

  Next, in the first step, the anode current collection pattern 8 is formed by screen printing or the like on the upstream portion of the intake port 1, the downstream portion of the exhaust port 2, and the periphery thereof, and also on the surface of the sacrificial member 10. The anode current collection pattern 8 is formed by screen printing or the like, and then both ends of the sacrificial member 10 are inserted into the intake port 1 and the exhaust port 2 of the holding member 3. As a result, the state shown in FIG. 3 is obtained. The anode current collection pattern 8 formed on the sacrificial member 10 is hidden in FIG. 3 because it is located on the far side of the page.

  Next, in the second step, a liquid phase paste 5 ′ obtained by diffusing the material of the fuel electrode layer 5 (see FIG. 2) and polymer particles, which are pore-forming materials for making it porous, into a solvent is used as a sacrificial member 10. Is applied to the entire exposed surface of the holding member 3 and the outer periphery of the downstream portion of the intake port 1 and the outer periphery of the upstream portion of the exhaust port 2 by a method such as dipping, and the connection boundary between the holding member 3 and the sacrificial member 10 by the liquid phase paste 5 ′. To be completely covered. As a result, the state shown in FIG. 4 is obtained. In order to use the fuel electrode layer 5 (see FIG. 2) as the support layer, the thickness of the liquid phase paste 5 'can be increased by increasing the number of times the liquid phase paste 5' is applied.

  Next, in the third step, after the liquid phase paste 5 ′ is dried, the sacrificial member 10 is removed, and then the liquid phase paste 5 ′ and the holding member 3 are fired under appropriate conditions (for example, 1200 to 1500 ° C.). To do. As a result, the state shown in FIG. 5 is obtained. As a method for removing the sacrificial member 10, for example, a method of heating the sacrificial member 10 to a temperature higher than the melting point of the sacrificial member 10 to make the sacrificial member 10 liquid and discharging it from the intake port 1 and the exhaust port 2 of the holding member 3. There is a method in which the sacrificial member 10 is burned off together with the pore former in the liquid phase paste 5 ′ by gradually heating to a temperature higher than the melting point. Since the volume of ceramic is greatly shrunk during firing, in order to prevent breakage due to this volume shrinkage, the material of the fuel electrode 5 and the material of the holding member 3 have the same shrinkage rate during firing. It is desirable to adjust the formulation.

  Next, in the fourth step, the liquid phase paste obtained by diffusing the solid oxide electrolyte layer 6 in the solvent is applied to the entire outer surface of the fuel electrode layer 5, the outer periphery of the downstream portion of the intake port 1 of the holding member 3, and the upstream of the exhaust port 2. It is applied to the outer periphery by dipping or the like, and the connection boundary between the holding member 3 and the fuel electrode layer 5 is completely covered with the liquid phase paste, and then fired. As a result, the state shown in FIG. 6 is obtained, and in the connection portion between the holding member 3 and the fuel cell structure 4 (see FIG. 2), the holding member 3 and the solid oxide electrolyte layer 6 that is dense and impervious to gas are sealed. A highly functional gas seal can be realized.

  Next, in the fifth step, the liquid phase paste obtained by diffusing the material of the oxidant electrode layer 7 and polymer particles, which are pore forming materials for making the porous material, into the solvent is used as the outer surface of the solid oxide electrolyte layer 6. Of these, it is applied to a region corresponding to the fuel electrode layer forming region inside the solid oxide electrolyte layer by a method such as dipping and then fired. As a result, the state shown in FIG. 7 is obtained.

  Finally, when the cathode current collection pattern 9 is formed on the holding member 3 and the fuel cell structure 4 by screen printing or the like, the structure shown in FIG. 2 is completed.

  In the manufacturing method according to the embodiment of the present invention described above, the fuel cell structure 4 is formed from the inner side in the order of the fuel electrode layer 5, the solid oxide electrolyte layer 6, and the oxidant electrode layer 7. However, it is of course possible to laminate in the reverse order. When the layers are stacked in the reverse order, the oxidant gas may be introduced from the intake port 1 of the holding member 3 into the gas flow path in the fuel cell structure 4 and supplied to the periphery of the fuel cell structure 4.

  In addition, as described above in the above description, it is possible to make any one of the three layers of the SOFC film thicker and use the thicker layer as a support layer. It can also be configured as a support layer. For example, the support layer may be first formed and fired on the sacrificial member, and then the SOFC film may be formed and fired. However, in this case, the fourth ceramic film needs to be formed porous so as not to inhibit the diffusion of the reaction gas.

  Further, in the manufacturing method according to the embodiment of the present invention described above, the fuel electrode layer 5 is fired and another layer is formed. However, the material of the sacrificial member 10 is dissolved or gasified to suck the inlet 1 of the holding member 3. If it can be discharged from the exhaust port 2, not only the porous fuel electrode layer 5 but also two layers including the dense solid oxide electrolyte layer 6 or three layers including the oxidant electrode layer 7 are applied. It is also possible to employ a process in which a plurality of layers are fired together.

  Further, in the fuel cell structure 4 obtained by the manufacturing method according to the embodiment of the present invention described above, each branch portion of the gas flow path is arranged in parallel. For example, a mesh shape as shown in FIG. By using the sacrificial member, the junction between the branch portions may be provided, and the mechanical strength of the fuel cell structure may be improved. Although it appears that there is no space for forming a multilayer film on the sacrificial member shown in FIG. 8 in the drawing, the film thickness of the multilayer film is actually much smaller than the outer shape of the sacrificial member. A multilayer film can be formed without problems.

  Further, in the manufacturing method according to the embodiment of the present invention described above, the holding member 3 having the intake port 1 and the exhaust port 2 is used, but instead of the holding member 3 having the intake port 1 and the exhaust port 2, FIG. Further, a first holding member 31 having an intake port 1 and a second holding member 32 having an exhaust port 2 as shown in FIG. 10 may be used. In this case, since the first holding member 31 and the second holding member 32 are independent from each other, the material of the fuel electrode 5 and the material of the first holding member 31 and the second holding member 2 are fired. Damage due to shrinkage difference is less likely to occur.

  Further, instead of the holding member 3 having one intake port 1 and one exhaust port 2, a holding member 33 having a plurality of intake ports 1 and a plurality of exhaust ports 2 as shown in FIG. 11 may be used. In this case, a plurality of fuel cell structures 4 can be formed simultaneously. Further, a layout in which a plurality of fuel cell structures 4 are connected in series with the anode current collection pattern 8 and the cathode current collection pattern 9 (the anode current collection pattern 8 and the cathode current collection pattern at the back of the page in the arrow portion in FIG. 11). By adopting a layout that connects to the electric pattern 9, a high voltage output can be realized.

  In the manufacturing method according to the embodiment of the present invention described above, the sacrificial member 10 is removed by the heat treatment. However, for example, depending on the material of the sacrificial member 10, the sacrificial member 10 can be removed by an etching process. In this case, the sacrificial member 10 may be removed after the SOFC film is completed (after all firing is completed).

DESCRIPTION OF SYMBOLS 1 Intake port 2 Exhaust port 3, 33 Holding member 4 Fuel cell structure 5 Fuel electrode layer 5 'Liquid phase paste 6 Solid oxide electrolyte layer 7 Oxidant electrode layer 8 Anode current collection pattern 9 Cathode current collection pattern 10 Sacrificial member 31 First holding member 32 Second holding member

Claims (5)

A fuel is provided on the surface of the sacrificial member having an outer shape corresponding to the shape of a gas flow path including an intake portion, a plurality of branch portions branched from the intake portion, and an exhaust portion where downstream sides of the plurality of branch portions meet. A structure forming step of forming a fuel cell structure having a multilayer structure including at least three layers of an electrode layer, an electrolyte layer, and an oxidant electrode layer;
A removal step of removing the sacrificial member in the middle of or after completion of the structure formation step. In the structure forming step, an end portion of the sacrificial member corresponding to the intake portion is inserted into the intake port of the first holding member, and corresponds to the exhaust portion with respect to the exhaust port of the second holding member. After the end portion of the sacrificial member is inserted and a layer that completely covers the connection boundary between the first holding member and the second holding member and the sacrificial member is formed,
The method for manufacturing a fuel cell structure according to claim 1, wherein the removing step is performed. The electrolyte layer is
Covering the entire outer surface of the fuel electrode layer or the oxidizer electrode layer formed inside the electrolyte layer, and formed inside the first holding member, the second holding member and the electrolyte layer. 3. The method of manufacturing a fuel cell structure according to claim 2, wherein the fuel cell structure is formed so as to completely cover a connection boundary with the fuel electrode layer or the oxidant electrode layer.   The method of manufacturing a fuel cell structure according to any one of claims 1 to 3, wherein the removing step is a step of removing the sacrificial member by heat treatment in the middle of the structure forming step.   The method of manufacturing a fuel cell structure according to any one of claims 1 to 4, wherein the sacrificial member is shaped to form a connection point between the branch portions.