JP2013097977A - Solid oxide fuel cell and fuel cell module and fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell which permits a solid electrolyte layer and an interconnector layer to be firmly joined, as well as a fuel cell module and a fuel cell device.SOLUTION: The principal plane on one side of a porous and planar support substrate 2 having opposed parallel principal planes and opposed side faces connecting the principal planes together has a fuel electrode layer 3, a solid electrolyte layer 4, and an oxygen electrode layer 5 disposed thereon, while the principal plane on the other side of the support substrate 2 has an interconnector layer 6 disposed thereon. The solid electrolyte layer 4 is extended from the principal plane on one side of the support substrate 2 to the other side thereof via the side face, and both ends of the solid electrolyte layer 4 and those of the interconnector layer 6 are joined. The support substrate 2 has bulged portions 10 which are respectively formed on a flat part 9 composed by the opposed parallel planes and on the side face side of the flat part 9, and which protrude toward the outside by 1.7 to 6% of the thickness between the principal planes rather than of the principal planes.

Description

  The present invention relates to a solid oxide fuel cell, a fuel cell module, and a fuel cell device.

  In recent years, various fuel cell devices in which a cell stack device in which a plurality of fuel cells are electrically connected in series are accommodated in a storage container have been proposed as next-generation energy.

  A fuel cell constituting a conventional cell stack device includes a porous fuel electrode layer, a dense solid electrolyte layer, and a porous oxygen electrode layer on one main surface of a support substrate having a gas flow path therein. Are stacked in this order, and a dense interconnector is provided on the other main surface.

  Then, both end portions of the fuel electrode layer and the solid electrolyte layer are extended to the other main surface through the side surface of the support substrate, and both end portions of the interconnector are superimposed on both end portions of the extended solid electrolyte layer. And joined (see, for example, Patent Document 1).

  In recent years, as a fuel cell, in order to reduce the stress generated in the solid electrolyte layer covering the side surface of the support substrate, the fuel cell has bulge portions that protrude outward from the main surface on both sides in the width direction of the support substrate. Is known (see, for example, Patent Document 2).

JP 2005-158529 A JP 2004-253279 A

  In the conventional fuel cell of Patent Document 2, a bulge portion protruding outward from the main surface is formed on both sides in the width direction of the support substrate, and the solid electrolyte layer and the interconnector layer are joined at the bulge portion. However, since current flows in the thickness direction of the support substrate, in order to shorten the current path and reduce the stress generated in the solid electrolyte layer covering the side surface of the support substrate, the protrusion from the main surface of the bulge portion In this case, there is a possibility that poor bonding between the solid electrolyte layer and the interconnector layer may occur.

  That is, when the amount of protrusion from the main surface of the bulge portion increases, the end portion of the solid electrolyte layer formed in the bulge portion in a state of being largely inclined with respect to the main surface of the support substrate, is substantially parallel to the main surface. The end of the connector will be joined, and the joining surface will be greatly inclined with respect to the main surface, and the joining area will be small, which may result in poor joining between the solid electrolyte layer and the interconnector layer. It was.

  An object of the present invention is to provide a solid oxide fuel cell, a fuel cell module, and a fuel cell device capable of firmly joining a solid electrolyte layer and an interconnector layer.

The solid oxide fuel cell of the present invention has opposing parallel main surfaces and opposing side surfaces connecting the main surfaces, and one side main surface of a support plate that is a porous flat plate, A first electrode, a solid electrolyte layer, and a second electrode are disposed, an interconnector layer is disposed on the other main surface of the support substrate, and the solid electrolyte layer is disposed from one main surface of the support substrate through the side surface. Extending to the other side, both end portions of the solid electrolyte layer and both end portions of the interconnector layer are joined, and the support substrate is a flat portion composed of the opposing parallel main surfaces; And a bulging portion that is formed on the side surface side of the flat portion and protrudes outward by 1.7 to 6% with respect to the thickness between the main surfaces with respect to the main surface.

  The solid oxide fuel cell of the present invention has a parallel main surface and opposing side surfaces that connect the main surfaces, and is a porous flat plate that also serves as the first electrode. A solid electrolyte layer and a second electrode are disposed on one main surface of the support substrate, an interconnector layer is disposed on the other main surface of the support substrate, and the solid electrolyte layer extends from the one main surface of the support substrate to the side surface. Through which the other end portion of the solid electrolyte layer and the both end portions of the interconnector layer are joined, and the support substrate is constituted by the opposed parallel main surfaces. And a bulge portion that is formed on the side surface side of the flat portion and protrudes outward from the main surface by 1.7 to 6% with respect to the thickness between the main surfaces. .

  A fuel cell module according to the present invention is characterized in that a plurality of the above-described fuel cells are housed in a housing container.

  A fuel cell device according to the present invention is characterized in that the fuel cell module described above and an auxiliary machine for operating the fuel cell module are housed in an outer case.

  In the solid oxide fuel cell according to the present invention, the bulge portion of the support substrate protrudes outward from the main surface by 1.7 to 6% with respect to the thickness between the main surfaces. The amount of protrusion from the main surface of the solid electrolyte layer is small, and the joining surface of the end portion of the solid electrolyte layer and the end portion of the interconnector layer can be joined to the main surface of the support substrate with a large area without being inclined so much. The interconnector layer can be firmly joined. Thereby, a fuel cell module and a fuel cell device excellent in long-term reliability can be provided.

An example of a solid oxide fuel cell is shown, (a) is a cross-sectional view, (b) is a perspective view of (a). (A) is a cross-sectional view of the support substrate of FIG. 1 exaggeratingly showing a bulge portion, and (b) is a cross-sectional view of a solid oxide fuel cell showing the bulge portion in an exaggerated manner. (A) is a cross-sectional view of a solid oxide fuel cell in which both ends of the solid electrolyte layer and both ends of the interconnector layer are joined to each other on the other principal surface of the flat portion, (b) The cross-sectional view of the solid oxide fuel cell in which the interconnector layer is disposed on the protrusion formed on the other principal surface between the both ends of the solid electrolyte layer and on both ends of the solid electrolyte layer It is. (A) is a side view schematically showing the cell stack device, and (b) is an enlarged cross-sectional view of a part of the cell stack device surrounded by a broken line frame of (a). It is an external appearance perspective view which shows an example of a fuel cell module. It is a disassembled perspective view which shows an example of a fuel cell apparatus.

1A and 1B show an embodiment of a fuel cell, where FIG. 1A is a cross-sectional view and FIG. 1B is a perspective view of FIG. In both drawings, each configuration of the fuel cell 1 is partially enlarged. The same members are denoted by the same reference numerals, and so on.

  The fuel cell 1 has a hollow flat plate shape, and has a columnar (more specifically, elliptical columnar) conductive porous support substrate (hereinafter sometimes simply referred to as a support substrate) 2 as a whole. I have. A plurality of gas passages 7 penetrating from one end to the other end in the longitudinal direction L are formed in the support substrate 2 at predetermined intervals, and the fuel cell 1 is provided with various members on the support substrate 2. Is configured.

  As is understood from the shapes shown in FIGS. 1 and 2, the support substrate 2 has a pair of main surfaces (flat surfaces) n parallel to each other and side surfaces (arc-shaped surfaces) connecting the pair of main surfaces n, respectively. m. The support substrate 2 includes a flat portion 9 formed of opposed parallel main surfaces n and a bulge portion 10 formed on each side m of the flat portion 9.

  On one main surface (upper surface) n of the support substrate 2, a dense interconnector 6 is provided from one end to the other end in the longitudinal direction L of the support substrate 2, and on the other main surface (lower surface) n, A laminated body (power generation unit) is provided in which the fuel electrode layer 3 as the first electrode, the solid electrolyte layer 4 and the oxygen electrode layer 5 as the second electrode are laminated in this order.

  The fuel electrode layer 3 is provided on the other main surface (flat surface: lower surface) n where the interconnector 6 is not provided, both side surfaces m, and part of one main surface so as to cover the outer surface of the fuel electrode layer 3. The solid electrolyte layer 4 is provided, and the fuel electrode layer 3 and the solid electrolyte layer 4 provided on the lower surface of the support substrate 2 are formed up to the main surface on one side via the side surface m. Both end portions of the interconnector layer 6 are laminated and bonded to both end portions.

  In other words, the plate-like porous substrate 2 having the parallel main surfaces n facing each other and the side surfaces m facing each other that connect the main surfaces n is composed of a dense solid electrolyte layer 4 and a dense interconnector layer 6. The fuel gas passing through the porous substrate 2 is prevented from leaking outside.

  The support substrate 2 has a bulging portion 10 that protrudes outward from the main surface n on the side surface m side of the flat portion 9 constituted by the parallel main surfaces n facing each other. The bulging portion 10 protrudes 1.7 to 6% outward from the main surface with respect to the thickness between the main surfaces. That is, the protrusion amount t1 from the main surface of the bulging portion 10 is 0.017 t to 0.06 t, where t is the thickness between the main surfaces of the support substrate 2 (thickness of the flat portion 9). The protrusion amount t1 of the bulging portion 10 from the main surface is preferably 0.03t to 0.06t. For example, when the thickness t of the flat portion 9 of the support substrate 2 is 5 mm or less, the protruding amount t1 from the main surface of the bulging portion 10 is desirably 50 to 300 μm. In particular, it is desirable that it is 100-200 micrometers. In the present invention, it is particularly useful when the thickness of the flat portion 9 of the support substrate 2 is 5 mm or less.

  As shown in FIG. 2B, both end portions of the interconnector layer 6 cover a part of the bulging portion 10 and are laminated on both end portions of the solid electrolyte layer 4 formed on the upper surface of the bulging portion 10. Are joined. The power generation part sandwiching the solid electrolyte layer 4 between the oxygen electrode layer 5 and the fuel electrode layer 3 is formed on the main surface of the flat part 9 between the bulging parts 10 formed on both sides in the width direction B of the support substrate 2. .

In such a solid oxide fuel cell, since the protruding amount t1 outward from the main surface of the bulging portion 10 of the support substrate 2 is set to 0.017 t to 0.06 t, the solid oxide fuel cell is disposed in the bulging portion 10. The stress in the solid electrolyte layer 4 can be reduced, and the protruding amount from the main surface of the bulging portion 10 is as small as 0.017 t to 0.06 t, so that the end of the solid electrolyte layer 4 and the end of the interconnector layer 6 The joining surface can be joined to the main surface of the support substrate 2 with a large area without being inclined so much, and the solid electrolyte layer 4 and the interconnector layer 6 can be joined firmly. Thereby, the fuel cell and fuel cell module excellent in long-term reliability, and also the fuel cell device can be provided.

  That is, in FIG. 2B, since the protruding amount t1 outward from the main surface of the bulging portion 10 is as small as 0.06 t or less, the end portion of the solid electrolyte layer 4 formed on the upper surface of the bulging portion 10 In addition, the end portions of the interconnector layer 6 can be laminated in a gently inclined state and can be joined in a wide area, and both end portions of the solid electrolyte layer 4 and both end portions of the interconnector layer 6 can be firmly joined.

  Further, although it is desirable to reduce the thickness of the solid electrolyte 4 and the interconnector layer 6 in order to improve the power generation performance, even if these thicknesses are reduced, the boundary between the flat portion on the lower surface of the support substrate 2 and the bulging portion 10 It is possible to suppress the occurrence of cracks or the like in the solid electrolyte layer 4 formed in the portion and the interconnector layer 6 formed in the boundary portion between the flat portion on the upper surface of the support substrate 2 and the bulging portion 10.

  Moreover, since the bulging part 10 protrudes outward from the main surface by 0.017 t or more, the stress of the solid electrolyte 4 in the vicinity of the side surface of the support substrate 2 having a thickness of 5 mm or less can be reduced. Thereby, it can suppress that peeling and a crack generate | occur | produce in the solid electrolyte 4 near the side surface of the support substrate 2. FIG.

  That is, although the power generation performance can be improved by making the support substrate 2 thinner, the thinner the support substrate 2 is, the smaller the radius of curvature of the side surface m of the support substrate 2 becomes, and the solid electrolyte layer 4 formed on this side surface m Although a high stress is generated, since the bulging portion 10 protrudes outward from the main surface by 0.017 t or more, the curvature radius of the side surface m of the support substrate 2 is increased, and the solid electrolyte formed on the side surface m The stress generated in the layer 4 can be reduced, and the occurrence of cracks and peeling in the solid electrolyte 4 can be suppressed.

  Here, the fuel battery cell 1 generates power when the facing portions of the fuel electrode layer 3 and the oxygen electrode layer 5 function as electrodes. That is, power is generated by flowing an oxygen-containing gas such as air outside the oxygen electrode layer 5 and flowing a fuel gas (hydrogen-containing gas) through the gas flow path 7 in the support substrate 2 and heating it to a predetermined operating temperature. . The current generated by such power generation is collected via an interconnector 6 provided on the surface of the support substrate 2.

  Below, each member which comprises the fuel battery cell 1 of this invention is demonstrated. The support substrate 2 is required to be gas permeable in order to allow the fuel gas flowing inside the gas passage 7 to permeate to the fuel electrode layer 3 and to be conductive in order to collect current via the interconnector 6. Therefore, for example, it is preferably formed of at least one of Ni and NiO and an inorganic oxide such as a specific rare earth oxide.

The specific rare earth oxide is used to bring the thermal expansion coefficient of the support substrate 2 close to the thermal expansion coefficient of the solid electrolyte layer 4, and is Y, Lu (lutetium), Yb, Tm (thulium), Er. A rare earth oxide containing at least one element selected from the group consisting of (erbium), Ho (holmium), Dy (dysprosium), Gd, Sm, Pr (praseodymium) and at least one of Ni and NiO Can be used in combination. Specific examples of such rare earth oxides include Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , Tm ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ , Dy ₂ O ₃ , Gd ₂ O. ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ , almost no solid solution and reaction with at least one of Ni and NiO, and the thermal expansion coefficient is almost the same as that of the solid electrolyte layer 4. Y ₂ O ₃ and Yb ₂ O ₃ are preferable because they are available and inexpensive.

In the present invention, the volume ratio after firing-reduction is Ni: rare earth element oxide in that the good conductivity of the support substrate 2 is maintained and the thermal expansion coefficient is approximated to that of the solid electrolyte layer 4. (For example, Ni: Y ₂ O ₃ ) is preferably in the range of 35:65 to 65:35 (Ni / (Ni + Y) is 65 to 86 mol% in molar ratio). The support substrate 2 may contain other metal components and oxide components as long as required characteristics are not impaired.

  Further, since the support substrate 2 is required to have gas permeability, it is usually preferable that the porosity is 30% or more, particularly 35 to 50%. The conductivity of the support substrate 2 is 50 S / cm or more, more preferably 300 S / cm or more, and particularly preferably 440 S / cm or more.

  The width of the support substrate 2 is, for example, 15 to 35 mm, the length of the arcuate surface m (the length of the arc) is, for example, 2 to 8 mm, and the thickness of the support substrate 2 (the thickness between the flat surfaces n). Is preferably 1.5 to 5 mm, for example. Thereby, current collecting property can be secured while maintaining a certain level of strength.

The fuel electrode layer 3 causes an electrode reaction, and can be formed from at least one of Ni and NiO, which are iron group metals, and ZrO _{2 in} which a rare earth element is dissolved. As the rare earth element, the rare earth elements exemplified in the support substrate 2 (Y and the like) can be used.

In the fuel electrode layer 3, and at least one of Ni and NiO, ZrO ₂ content of the rare earth element is solid-solved is fired - volume ratio after reduction, Ni: ZrO ₂ (e.g. a rare earth element in solid solution, Ni: YSZ) is preferably in the range of 35:65 to 65:35. Further, the fuel electrode layer 3 is porous, and the porosity thereof is preferably 15% or more, particularly preferably in the range of 20 to 40%, and the thickness thereof can be set to 1 to 30 μm.

The solid electrolyte layer 4 uses a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing a rare earth element such as 3 to 15 mol% of Y (yttrium), Sc (scandium), Yb (ytterbium). Is preferred. As the rare earth element, Y is preferable because it is inexpensive. Further, the solid electrolyte layer 4 is desirably a dense material having a relative density (according to Archimedes method) of 93% or more, particularly 95% or more in terms of preventing gas permeation, and a thickness of 5 to 50 μm. Preferably there is. The solid electrolyte layer 4 may be composed of a lanthanum gallate material or a ceria material.

  In addition, the solid electrolyte layer 4 and the oxygen electrode layer 5 are firmly joined between the solid electrolyte layer 4 and the oxygen electrode layer 5 described later, and the components of the solid electrolyte layer 4 and the components of the oxygen electrode layer 5 are The intermediate layer 8 can be provided for the purpose of suppressing the formation of a reaction layer having a high electrical resistance by reaction, and the fuel cell 1 shown in FIG. 1 shows an example provided with the intermediate layer 8. .

Here, the intermediate layer 8 can be formed with a composition containing Ce (cerium) and another rare earth element. For example, (CeO ₂ ) _1-x (REO _1.5 ) _x (RE is Sm , Y, Yb, and Gd, and x preferably has a composition represented by 0 <x ≦ 0.3. Furthermore, from the viewpoint of reducing electrical resistance, it is preferable to use Sm or Gd as RE, for example, it is preferably made of CeO ₂ in which 10 to 20 mol% of SmO _1.5 or GdO _1.5 is dissolved. . The intermediate layer 8 can be composed of, for example, two layers. In this case, after the first layer is provided by co-firing with the solid electrolyte layer 4, the second layer is separately provided at a temperature lower by 200 ° C. or more than the co-firing. It is preferable to fire.

  Further, the oxygen electrode layer 5 needs to have gas permeability. Therefore, the conductive ceramic (perovskite oxide) forming the oxygen electrode layer 5 has a porosity of 20% or more, particularly 30 to 50%. It is preferable to be in the range. Furthermore, the thickness of the oxygen electrode layer 5 can be set to 30 to 100 μm from the viewpoint of current collection.

The conductive ceramic constituting the oxygen electrode layer 5 is preferably formed of a conductive ceramic made of a sintered body mainly composed of a so-called ABO ₃ type perovskite complex oxide, and is a transition metal perovskite type. oxide, LaSrCoFeO ₃ type oxide in particular co Sr (strontium) and La (lanthanum) has the a site (e.g. LaSrCoFeO _3), LaMnO ₃ type oxide (e.g., LaSrMnO _3), LaFeO ₃ type oxide (e.g. LaSrFeO ₃ ) And LaCoO ₃ -based oxides (for example, LaSrCoO ₃ ) are preferable, and LaSrCoFeO ₃ -based oxides are particularly preferable from the viewpoint of high electrical conductivity at an operating temperature of about 600 to 1000 ° C. In the perovskite oxide, Fe (iron) or Mn (manganese) may exist at the B site together with Co (cobalt).

The interconnector 6 is preferably formed of dense conductive ceramics. However, since the interconnector 6 is in contact with the fuel gas (hydrogen-containing gas) and the oxygen-containing gas, the interconnector 6 may have reduction resistance and oxidation resistance. is necessary. For this reason, lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides) are generally used as conductive ceramics having reduction resistance and oxidation resistance, and particularly the support substrate 2 and the solid electrolyte layer 4. For the purpose of bringing the thermal expansion coefficient closer, LaCrO ₃ -based oxide is used. The interconnector 6 can also be formed by using, for example, a LaTiO ₃ oxide, a heat resistant metal, or a conductive ceramic other than the LaCrO ₃ oxide.

  Moreover, the thickness of the interconnector 6 can be 10-50 micrometers from the point of the leak prevention of a gas and an electrical resistance. If the thickness is smaller than this range, gas leakage is liable to occur. If the thickness is larger than this range, the electric resistance is large, and the current collecting function may be lowered due to a potential drop.

  Although not shown, it is preferable to provide a P-type semiconductor layer on the outer surface (upper surface) of the interconnector 6. By connecting a current collecting member (not shown) to the interconnector 6 via a P-type semiconductor layer, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and a reduction in current collecting performance is effectively avoided. It becomes possible.

As such a P-type semiconductor layer, a layer made of a transition metal perovskite oxide can be exemplified. Specifically, P having a high electron conductivity, for example, P made of at least one kind of LaMnO ₃ -based oxide, LaFeO ₃ -based oxide, LaCoO ₃ -based oxide in which Mn, Fe, Co, etc. exist at the B site. Type semiconductor ceramics can be used. Such a P-type semiconductor layer can generally have a thickness of 30 to 100 μm.

  In addition, an adhesion layer (not shown) can be provided between the support substrate 2 and the interconnector 6 in order to reduce a difference in thermal expansion coefficient between the interconnector 6 and the support substrate 2.

The adhesion layer can be formed of, for example, at least one of rare earth element oxide, ZrO _{2 in which} a rare earth element is dissolved, and CeO ₂ in which a rare earth element is dissolved, and at least one of Ni and NiO. More specifically, for example, a composition comprising at least one of Y ₂ O ₃ and Ni and NiO, a composition comprising at least one of ZrO ₂ (YSZ) in which Y is solid-solved, Ni and NiO, Y, Sm, It can be formed from a composition comprising CeO ₂ in which Gd or the like is dissolved, and at least one of Ni and NiO. Note that the rare earth element oxide or rare earth element ZrO ₂ (CeO ₂ ) and at least one of Ni and NiO have a volume ratio in the range of 40:60 to 60:40 after firing and reduction. It is preferable to form as follows.

  In the case of providing the adhesion layer, by appropriately setting the thickness of the adhesion layer and providing the end portion of the interconnector 6 on the support substrate 2 side of the solid electrolyte layer 4 and the fuel electrode layer 3, It can suppress that the interconnector 6, the solid electrolyte layer 4, and the fuel electrode layer 3 produce peeling.

  A method for producing the fuel cell 1 of the present invention described above will be described.

First, a clay is prepared by mixing at least one powder of Ni and NiO, a powder of a rare earth oxide such as Y ₂ O ₃ , an organic binder, and a solvent, and an extrusion molding method using the clay. Thus, a support substrate molded body is prepared and dried. In addition, you may use the calcined body which calcined the support substrate molded object at 900-1000 degreeC for 2 to 6 hours as a support substrate molded object.

  In order to produce a support substrate having a bulge as shown in FIG. 2A, an extrusion mold that forms the bulge is used.

Next, the raw material of ZrO ₂ (YSZ) in which NiO and Y ₂ O ₃ are dissolved, for example, is weighed and mixed according to a predetermined composition. Thereafter, an organic binder and a solvent are mixed with the mixed powder to prepare a slurry for the fuel electrode layer.

Further, a slurry obtained by adding toluene, a binder, a commercially available dispersant, etc. to a ZrO ₂ powder in which a rare earth element is solid-solubilized is molded to a thickness of 7 to 75 μm by a method such as a doctor blade. A solid electrolyte layer molded body is produced. A fuel electrode layer slurry is applied on the obtained sheet-shaped solid electrolyte layer molded body to form a sheet-shaped laminate molded body in which the fuel electrode layer molded body is formed. This sheet-like laminate compact is laminated on the support substrate compact with the fuel electrode layer compact as the bottom surface.

  Subsequently, an intermediate layer 8 molded body disposed between the solid electrolyte layer 4 and the oxygen electrode layer 5 is formed.

For example, toluene is added as a solvent to a raw material powder using CeO ₂ powder in which GdO _1.5 is dissolved, to prepare a slurry for an intermediate layer, and this slurry is applied on a solid electrolyte layer molded body to form an intermediate layer A molded body is produced. In addition, a sheet-like intermediate layer molded body may be prepared and laminated on the solid electrolyte layer molded body.

Subsequently, an interconnector material (for example, LaCrO ₃ oxide powder containing Mg), an organic binder, and a solvent are mixed to prepare a slurry, which is then printed on the support substrate molded body of the laminate molded body by screen printing. Applied. In addition, the interconnector was provided so that it might overlap with the edge part in the circumferential direction of a solid electrolyte layer molded object.

  Next, the above-mentioned laminate molded body is subjected to binder removal treatment and simultaneously sintered (simultaneously fired) in an oxygen-containing atmosphere at 1400 ° C. to 1600 ° C. for 2 to 6 hours.

  When the intermediate layer 8 is formed from two layers, the intermediate layer on the oxygen electrode layer side is formed by applying the intermediate layer slurry to the upper surface of the co-fired intermediate layer 8 (first layer). And firing at a temperature lower by 200 ° C. or more than the temperature at the time of the simultaneous firing.

Next, a slurry containing an oxygen electrode layer material (for example, LaCoO ₃ oxide powder), a solvent and a pore-forming agent is applied on the intermediate layer 8 by dipping or the like, and baked at 1000 to 1300 ° C. for 2 to 6 hours. Thus, the fuel battery cell 1 having the structure shown in FIG. 1 can be manufactured. In addition, it is preferable that the fuel cell 1 thereafter causes hydrogen gas to flow therein to perform the reduction treatment of the support substrate 2 and the fuel electrode layer 3. In that case, it is preferable to perform a reduction process at 750-1000 degreeC for 5 to 20 hours, for example.

  FIG. 3A shows another form of the solid oxide fuel cell. In this form, the solid electrolyte layer 4 is flat from the main surface on one side of the support substrate 2 via the bulge 10. 9 is extended to the other main surface m of the flat portion 9, and both ends of the solid electrolyte layer 4 and both ends of the interconnector layer 6 are joined to each other on the other main surface of the flat portion 9. In other words, the solid electrolyte layer 4 extends to the other main surface of the flat portion 9, and the end of the solid electrolyte layer 4 is formed on the other main surface substantially parallel to the main surface. The end portion of the interconnector layer 6 is joined to the upper surface of the end portion.

  In such a solid oxide fuel cell, the interconnector layer 6 slurry is applied and fired on and between both ends of a solid electrolyte layer molded body that is substantially parallel to the main surface and flat. Therefore, since both ends of the solid electrolyte layer 4 and both ends of the interconnector layer 6 can be joined on a flat principal surface, manufacturing is easy, the joining surface is parallel to the principal surface, and the joining area is widened. The bonding strength can be improved.

  FIG. 3B shows still another form of the solid oxide fuel cell. In this form, the solid electrolyte layer 4 is flattened from the main surface on one side of the support substrate 2 through the bulging portion 10. The other side main surface m of the portion 9 is extended to the other side main surface between both end portions of the solid electrolyte layer 4, and the outer surface has a flat protrusion 2 a. The height of the protruding portion 2 a from the surface is substantially the same as the height of the end portion of the solid electrolyte layer 4 from the other main surface of the support substrate 2. And in the other main surface of the flat part 9, the interconnector layer 6 is laminated | stacked and joined to the upper surface of the both ends of the solid electrolyte layer 4, and the upper surface of the protrusion part 2a.

  In such a solid oxide fuel cell, the slurry of the interconnector layer 6 is applied between both ends of the flat solid electrolyte layer molded body and fired, so that the solid electrolyte is formed on the flat main surface. Since both ends of the layer 4 and both ends of the interconnector layer 6 can be joined, manufacturing is easy, the joining surface is parallel to the main surface, the joining area is widened, the joining strength can be improved, and the interconnector layer 6 Since the thickness is substantially uniform, the interconnector layer 6 can be firmly and reasonably bonded to the support substrate 2.

  FIG. 4 shows an example of a cell stack device configured by electrically connecting a plurality of the above-described fuel cells 1 in series via a current collecting member 14, and (a) shows a cell stack. The side view which shows the stack apparatus 12 schematically, (b) is a partial enlarged plan view of the cell stack apparatus 12 of (a), and shows the part surrounded by the dotted frame shown in (a). Yes. In addition, in (b), in order to clarify, the part corresponding to the part enclosed with the dotted-line frame shown by (a) is shown with the arrow.

  In the cell stack device 12, each fuel cell 1 is erected and arranged via a current collecting member 14 to constitute a cell stack 13, and one end (lower end) of each fuel cell 1 is formed. ) Is fixed to the gas tank 15 for supplying the fuel gas to the fuel cell 1 by an adhesive such as a glass sealing material. In addition, an elastically deformable conductive member 16 having a lower end fixed to the gas tank 15 is provided so as to sandwich the cell stack 13 from both ends in the arrangement direction of the fuel cells 1.

Further, in the conductive member 16 shown in FIG. 4, a current for extracting a current generated by power generation of the cell stack 13 (fuel cell 1) in a shape extending outward along the arrangement direction of the fuel cells 1. A drawer portion 17 is provided.

  FIG. 5 is an external perspective view showing an example of the fuel cell module 20 in which the cell stack device 12 is accommodated in a storage container. The cell stack device 12 shown in FIG. It is configured to store.

  In order to obtain fuel gas used in the fuel cell 1, a reformer 22 for reforming raw fuel such as natural gas or kerosene to generate fuel gas is disposed above the cell stack 13. ing. The fuel gas generated by the reformer 22 is supplied to the gas tank 15 via the gas flow pipe 23 and supplied to the gas passage 7 provided inside the fuel battery cell 1 via the gas tank 15.

  FIG. 5 shows a state where a part (front and rear surfaces) of the storage container 21 is removed and the cell stack device 12 and the reformer 22 housed inside are taken out rearward. Here, in the fuel cell module 20 shown in FIG. 5, the cell stack device 12 can be slid and stored in the storage container 21. The cell stack device 12 may include a reformer 22.

  Further, in FIG. 5, the oxygen-containing gas introduction member 24 provided inside the storage container 21 is disposed between the cell stacks 13 juxtaposed to the gas tank 15, and the oxygen-containing gas is adapted to the flow of the fuel gas. The oxygen-containing gas is supplied to the lower end of the fuel cell 1 so that the fuel cell 1 flows laterally from the lower end toward the upper end. And by burning the fuel gas discharged from the fuel gas passage 7 of the fuel battery cell 1 and the oxygen-containing gas on the upper end side of the fuel battery cell 1, the temperature of the fuel battery cell 1 can be raised, The activation of the cell stack device 12 can be accelerated. Further, by burning the fuel gas and the oxygen-containing gas discharged from the fuel gas passage 7 of the fuel battery cell 1 at the upper end side of the fuel battery cell 1, the fuel cell 1 (cell stack 13) is disposed above. It is possible to efficiently warm the reformer 22 disposed in the. Thereby, the reforming reaction can be efficiently performed in the reformer 22.

  Further, in the fuel cell module 20, the cell stack device 12 configured using the fuel cell 1 having improved long-term reliability is stored in the storage container 21. Therefore, the fuel cell having improved long-term reliability. Module 20 may be used.

  FIG. 6 is an exploded perspective view showing an example of a fuel cell device in which the fuel cell module 20 shown in FIG. 5 and an auxiliary machine for operating the fuel cell stack device 12 are housed in an outer case. . In FIG. 6, a part of the configuration is omitted.

  The fuel cell device 25 shown in FIG. 6 has a module housing chamber 29 in which an inside of an exterior case composed of a support column 26 and an exterior plate 27 is vertically divided by a partition plate 28 and the upper side thereof houses the above-described fuel cell module 20. The lower side is configured as an auxiliary equipment storage chamber 30 for storing auxiliary equipment for operating the fuel cell module 20. It should be noted that the accessories stored in the accessory storage chamber 30 are omitted.

  Further, the partition plate 28 is provided with an air circulation port 31 for flowing the air in the auxiliary machine storage chamber 30 to the module storage chamber 29 side, and a part of the exterior plate 27 constituting the module storage chamber 29 An exhaust port 32 for exhausting air in the module storage chamber 29 is provided.

  In such a fuel cell device 25, as described above, the fuel cell module 20 capable of improving long-term reliability is housed in the module housing chamber 29, so that the fuel with improved long-term reliability is provided. The battery device 25 can be obtained.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention. For example, you may form various intermediate | middle layers according to a function between each member.

  In the above embodiment, the fuel electrode layer 3 is used as the first electrode and the oxygen electrode layer 5 is used as the second electrode. However, the oxygen electrode layer may be used as the first electrode and the fuel electrode layer may be used as the second electrode. . In this case, the oxygen-containing gas flows in the support substrate 2.

  Furthermore, in the above embodiment, the fuel electrode layer 3, the solid electrolyte layer 4, and the oxygen electrode layer 5 are formed on the support substrate 2. However, the fuel cell in which the solid electrolyte layer and the oxygen electrode layer are formed on the support substrate that also serves as the fuel electrode. Even in the fuel cell in which the solid electrolyte layer and the fuel electrode layer are formed on the support substrate that also serves as the oxygen electrode, the same effect as the above embodiment can be obtained.

First, NiO powder having an average particle diameter of 0.5 μm and Y ₂ O ₃ powder having an average particle diameter of 0.9 μm are calcined and reduced, so that the volume ratio is 48% by volume for Ni and 52% by volume for Y ₂ O _3. The kneaded material prepared with an organic binder and a solvent was molded by extrusion molding, dried and degreased to prepare a support substrate molded body. As the mold used for molding, a mold was used such that the protrusion amount t1 of the bulge portion on the support substrate becomes the protrusion amount shown in Table 1 after firing.

Next, using a slurry obtained by mixing a ZrO ₂ powder (solid electrolyte layer raw material powder) having a particle diameter of 0.8 μm by solid micro-solution method in which 8 mol% of Y is dissolved, an organic binder, and a solvent, A solid electrolyte layer sheet was prepared by a doctor blade method.

Next, a slurry for a fuel electrode layer is prepared by mixing a NiO powder having an average particle size of 0.5 μm, a ZrO ₂ powder in which Y ₂ O ₃ is dissolved, an organic binder, and a solvent, and the fuel electrode layer is formed on the solid electrolyte layer sheet. A sheet-like laminated body formed by applying a layer slurry to form a fuel electrode layer formed body was formed. Subsequently, the surface on the fuel electrode layer molded body side of the multilayer molded body was laminated at a predetermined position of the support substrate molded body.

  Subsequently, the laminated body obtained by laminating the fuel electrode layer molded body and the solid electrolyte layer molded body as described above was calcined at 1000 ° C. for 3 hours.

Next, an intermediate layer prepared by adding and mixing an acrylic binder and toluene to a composite oxide containing 85 mol% of CeO ₂ and 15 mol% of another rare earth oxide (GdO _1.5 ). The slurry for coating was applied on the solid electrolyte layer calcined body by a screen printing method to produce an intermediate layer molded body.

Subsequently, using the slurry for an interconnector in which a LaCrO ₃ oxide, an organic binder, and a solvent are mixed, the fuel electrode layer molded body and the other side of the support substrate molded body on which the solid electrolyte layer molded body is not formed are used. On the flat part, the interconnector was provided by screen printing so that both ends of the interconnector were positioned on the solid electrolyte layer.

  And each laminated body by which these each layer was laminated | stacked was co-fired (sintered) for 3 hours at 1510 degreeC in air | atmosphere.

Next, a mixed liquid composed of LaSrCoFeO ₃ powder having an average particle diameter of 2 μm and isopropyl alcohol is prepared, and applied to the surface of the intermediate layer of the laminated sintered body to form an oxygen electrode layer formed body at 1100 ° C. After baking for 4 hours, an oxygen electrode layer was formed, and fuel cells having the structure shown in Table 1 were produced.

  The size of the produced fuel cell is 25 mm × 200 mm, the porosity of the support substrate is 35%, the thickness of the fuel electrode layer is 10 μm, the porosity is 24%, the thickness of the oxygen electrode layer is 50 μm, the porosity is 40%, The relative density of the solid electrolyte layer was 97%.

  Each fuel cell in which the thickness t between the main surfaces of the support substrate of the fuel cell, the thickness of the solid electrolyte layer, the thickness of the interconnector layer, the presence or absence of the bulging portion, and the protruding amount t1 from the main surface of the bulging portion are changed. Ten pieces were produced. The protrusion amount t1 is described as a ratio to the thickness t between the main surfaces.

  For these fuel cells, the presence or absence of cracks and delamination at the joints between both ends of the solid electrolyte layer and both ends of the interconnector layer was confirmed by observation with a scanning electron microscope. Described. In Table 1, 3/10 means that cracking or peeling occurred in three of ten fuel cells.

  From Table 1, when the protrusion amount t1 outward from the main surface of the bulging portion of the support substrate is 1.7 to 6% with respect to the thickness t between the main surfaces, both end portions of the solid electrolyte layer and It can be seen that there is no cracking or peeling at the joint portion between the both end portions of the interconnector layer, and the both end portions of the solid electrolyte layer and the both end portions of the interconnector layer can be firmly joined.

1: Fuel cell 2: Support substrate 2a: Protruding part 3: Fuel electrode layer 4: Solid electrolyte layer 5: Oxygen electrode layer 6: Interconnector layer 7: Gas passage 9: Flat part 10: Swelling part 12: Cell stack device 20: Fuel cell module 25: Fuel cell device

Claims (6)

A first electrode, a solid electrolyte layer, and a second electrode are formed on one side main surface of a support substrate having a porous flat plate shape, having opposing parallel main surfaces and opposing side surfaces connecting the main surfaces. An interconnector layer is disposed on the other principal surface of the support substrate, the solid electrolyte layer is extended from one principal surface of the support substrate to the other side through the side surface, and the solid electrolyte layer Both end portions and both end portions of the interconnector layer are joined, and the support substrate is formed on each of the opposed flat main surfaces and the side surfaces of the flat portions. A solid oxide fuel cell, characterized by having a bulging portion protruding outward by 1.7 to 6% with respect to the thickness between the main surfaces rather than the surface.   A solid electrolyte layer and a second electrode are formed on one side main surface of a support substrate which has a parallel main surface facing each other and a side surface facing each other that connects the main surfaces and is a porous flat plate and also serves as the first electrode. An interconnector layer is disposed on the other main surface of the support substrate, the solid electrolyte layer is extended from one main surface of the support substrate to the other side via the side surface, and the solid electrolyte layer And both ends of the interconnector layer are joined to each other, and the support substrate is formed on each of the opposing parallel main surfaces and on the side surface side of the flat portion. A solid oxide fuel cell, characterized by having a bulging portion protruding outward by 1.7 to 6% with respect to the thickness between the main surfaces rather than the main surfaces.   The solid electrolyte layer extends from the one side main surface of the support substrate to the other side main surface of the flat portion via the bulge portion, and both ends of the solid electrolyte layer on the other side main surface of the flat portion The solid oxide fuel cell according to claim 1, wherein both ends of the connector and the interconnector layer are joined.   The support substrate has a protrusion with a flat outer surface on the other main surface between both ends of the solid electrolyte layer, and the height of the protrusion from the other main surface of the support substrate is The height of the end of the solid electrolyte layer from the other principal surface of the support substrate is substantially the same height, and both ends of the interconnector layer are disposed on both ends of the solid electrolyte layer. The solid oxide fuel cell according to claim 3, wherein   A fuel cell module comprising a plurality of solid oxide fuel cells according to any one of claims 1 to 4 in a storage container.   6. A fuel cell device comprising: the fuel cell module according to claim 5; and an auxiliary machine for operating the fuel cell module, housed in an outer case.

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