JP5489673B2 - FUEL CELL CELL, CELL STACK DEVICE EQUIPPED WITH THE SAME, FUEL CELL MODULE, AND FUEL CELL DEVICE - Google Patents

Description

  The present invention includes an interconnector, a fuel electrode layer, and a solid electrolyte layer on a surface of a conductive support, and an air electrode layer is provided on the solid electrolyte layer so as to face the fuel electrode layer through an intermediate layer. The present invention relates to a provided fuel cell, a cell stack device, a fuel cell module, and a fuel cell device.

  In recent years, as next-generation energy, a plurality of fuel cells that can obtain electric power using hydrogen-containing gas (fuel gas) and air (oxygen-containing gas) are erected and electrically connected in series. The cell stack is fixed to a manifold for supplying fuel gas to the fuel cell to form a cell stack device, and the fuel cell module and the fuel cell module are stored in the outer casing. Various fuel cell devices housed in the interior have been proposed (see, for example, Patent Document 1).

  Further, there is provided a fuel cell having an intermediate layer for preventing diffusion of an element contained in the air electrode layer and an element contained in the solid electrolyte layer between the air electrode layer and the solid electrolyte layer. It is known (for example, refer to Patent Document 2).

JP 2007-59377 A JP 2003-288914 A

  By the way, during the production of the fuel cell or during the operation of the fuel cell device, stress is generated inside the fuel cell due to the difference in thermal expansion of each member constituting the fuel cell and the reduction process, and the intermediate layer and In some cases, the air electrode layer peeled off.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fuel cell, a cell stack device, a fuel cell module, and a fuel cell device that can suppress separation of the intermediate layer and the air electrode layer during operation of the fuel cell device. .

The fuel cell of the present invention includes an interconnector on the surface of the conductive support, and a fuel electrode layer, a solid electrolyte layer, an intermediate layer, and an air electrode layer are laminated in this order adjacent to the interconnector. A fuel cell including a power generation unit, wherein the porosity of the intermediate layer is 40 to 60%, the average pore diameter in the intermediate layer is 1 to 3 μm, and the air electrode layer is the intermediate layer A first air electrode layer disposed on the first air electrode layer; and a second air electrode layer disposed on the first air electrode layer, wherein the porosity of the first air electrode layer is the second air electrode. smaller than the porosity of the electrode layer, and Ri porosity der following the intermediate layer, the porosity of the intermediate layer, wherein the smaller than the porosity of the second cathode layer.

In such a fuel cell, since the porosity of the intermediate layer is 40 to 60% and the average pore diameter in the intermediate layer is 1 to 3 μm, the fuel cell is manufactured and the fuel cell device is operated. Even when stress is generated inside the fuel cell due to a difference in thermal expansion of each member constituting the fuel cell or a reduction process, the average pore diameter provided in the intermediate layer is 1 to 3 μm. Thus, the stress of the fuel cell can be effectively relieved by the large number of pores, and separation between the intermediate layer and the air electrode layer can be suppressed. Thereby, it can be set as the fuel cell which improved long-term reliability. In such a fuel cell, since the porosity of the first air electrode layer is smaller than the porosity of the second air electrode layer disposed on the first air electrode layer, while maintaining a high current collecting property The bonding area with the intermediate layer can be increased, and the intermediate layer and the air electrode layer can be prevented from peeling off. Furthermore, since the porosity of the first air electrode layer is equal to or less than the porosity of the intermediate layer, the intermediate layer can relieve the stress generated in the air electrode layer during power generation. Generation of peeling can be further suppressed. Thereby, it can be set as the fuel cell which improved long-term reliability.

In the fuel cell of the present invention, it is preferable that the porosity of the first air electrode layer is 30 to 55%, and the porosity of the second air electrode layer is 50 to 70%.

  A cell stack device according to the present invention includes a cell stack in which a plurality of the fuel cells described above are arranged in a standing state via a current collecting member and are electrically connected in series. In addition to fixing the lower end portion of the fuel cell and a manifold for supplying fuel gas to the fuel cell, a cell stack device with improved long-term reliability can be obtained.

  Since the fuel cell module of the present invention is formed by housing the cell stack device described above in a storage container, the fuel cell module can be improved in long-term reliability.

  The fuel cell device according to the present invention comprises the above-described fuel cell module and an auxiliary machine for operating the fuel cell module in an outer case, and thus a fuel cell device with improved long-term reliability. can do.

The fuel battery cell of the present invention has a stress inside the fuel battery cell due to a difference in thermal expansion of each member constituting the fuel battery cell or deformation caused by the reduction process at the time of manufacturing the fuel battery cell or operating the fuel battery device. when occurs even with the porosity of the intermediate layer is 40 to 60%, Ri average pore diameter of 1 to 3μm der in the intermediate layer, first the air electrode layer, disposed on the intermediate layer
An air electrode layer and a second air electrode layer disposed on the first air electrode layer, wherein the porosity of the first air electrode layer is smaller than the porosity of the second air electrode layer; and Since the porosity of the intermediate layer is lower than the porosity, the stress of the fuel cell can be effectively relieved by the large number of pores, and the separation between the intermediate layer and the air electrode layer can be suppressed. Thereby, it can be set as the fuel cell which improved long-term reliability.

  A cell stack device according to the present invention includes a cell stack in which a plurality of the above-described fuel cells are arranged upright via a current collecting member and electrically connected in series, and the fuel cell Since the lower end portion is fixed and the manifold for supplying the reaction gas to the fuel cell is provided, a cell stack device with improved long-term reliability can be obtained.

  Since the fuel cell module of the present invention is formed by storing the cell stack device in a storage container, the fuel cell module can be improved in long-term reliability.

  The fuel cell device of the present invention is a fuel cell device with improved long-term reliability, because the fuel cell module and an auxiliary machine for operating the fuel cell module are housed in an outer case. be able to.

An example of the fuel cell of this invention is shown, (a) is a cross-sectional view, (b) is a perspective view of (a). 1 shows an example of a fuel cell stack device of the present invention, (a) is a side view schematically showing the fuel cell stack device, and (b) is a portion surrounded by a dotted frame of the fuel cell stack device of (a). It is the top view to which a part of was expanded. It is an external appearance perspective view which shows an example of the fuel cell module of this invention. It is a disassembled perspective view which shows an example of the fuel cell apparatus of this invention.

  FIG. 1 shows an example of a fuel cell according to the present invention, in which (a) is a cross-sectional view and (b) is a perspective view of (a). 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 includes a conductive support 2 having an elliptical column shape as a whole. A plurality of fuel gas passages 3 penetrating from one end to the other end in the longitudinal direction are formed in the inside of the conductive support 2 at predetermined intervals, and the fuel cell 1 is placed on the conductive support 2 in various ways. It has the structure where the member of this was provided.

  As understood from the shape shown in FIG. 1, the conductive support 2 is composed of a pair of flat surfaces n parallel to each other and arcuate surfaces (side surfaces) m connecting the pair of flat surfaces n. Has been. A fuel electrode layer 4 is provided so as to cover one surface (lower surface) of the flat surface n and the arc-shaped surfaces m on both sides, and a solid electrolyte layer 5 is laminated so as to cover the fuel electrode layer 4. Yes. An air electrode layer 7 is laminated on the solid electrolyte layer 5 so as to face the fuel electrode layer 4 with the intermediate layer 6 interposed therebetween. An interconnector 9 is formed on the other flat surface n on which the fuel electrode layer 4 and the solid electrolyte layer 5 are not stacked, with an adhesion layer 8 interposed therebetween.

  As is clear from FIG. 1, the fuel electrode layer 4 and the solid electrolyte layer 5 extend to both sides of the interconnector 9 (adhesion layer 8) via the arcuate surfaces m at both ends. The surface is configured not to be exposed to the outside. FIG. 1 shows an example in which the fuel electrode layer 4 overlaps the side surface of the adhesion layer 8 and the solid electrolyte layer 5 overlaps the side surface of the interconnector 9, but the adhesion layer 8 and the interconnector 9 have appropriate thicknesses. For example, the fuel electrode layer 4 and the solid electrolyte layer 5 can be arranged so as to overlap the side surface of the adhesion layer 8, and a part of the fuel electrode layer 4 overlaps the side surface of the interconnector 9. It can also be arranged. Furthermore, the fuel electrode layer 4, the solid electrolyte layer 5, the adhesion layer 8, and the interconnector 9 can be arranged so that both end portions thereof overlap in this order.

  Here, in the fuel cell 1, the portion where the fuel electrode layer 4, the solid electrolyte layer 5, the intermediate layer 6 and the air electrode layer 7 are stacked functions as a power generation unit to generate power. That is, an oxygen-containing gas such as air is allowed to flow outside the air electrode layer 7, and a fuel gas (hydrogen-containing gas) is allowed to flow through the fuel gas passage 3 in the conductive support 2 to be heated to a predetermined operating temperature. To generate electricity. And the electric current produced | generated by this electric power generation is collected through the interconnector 9 laminated | stacked on the electroconductive support body 2. FIG.

  Below, each member which comprises the fuel battery cell 1 of this invention is demonstrated.

  The conductive support 2 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode layer 4 and to be conductive in order to collect current via the interconnector 9. For example, it is preferably formed of at least one of Ni and NiO and a specific rare earth oxide.

The specific rare earth oxide is used to make the thermal expansion coefficient of the conductive support 2 close to the thermal expansion coefficient of the solid electrolyte layer 5, and is Y, Lu (lutetium), Yb, Tm (thulium). , Er (erbium), Ho (holmium), Dy (dysprosium), Gd, Sm, Pr (praseodymium), the rare earth oxide containing at least one element selected from 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 can be exemplified, and there is almost no solid solution or 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 5. 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 in that the good conductivity of the conductive support 2 is maintained and the thermal expansion coefficient is approximated to that of the solid electrolyte layer 5. It is preferable that the oxide (for example, Ni: Y ₂ O ₃ ) is in the range of 35:65 to 65:35 (Ni / (Ni + Y) is 65 to 86 mol% in molar ratio). The conductive support 2 may contain other metal components and oxide components as long as required characteristics are not impaired.

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

  Note that the length of the flat surface n of the conductive support 2 (length in the width direction of the conductive support 2) is usually 15 to 35 mm, and the length of the arcuate surface m (arc length) is 2. The thickness of the conductive support 2 (thickness between the flat surfaces n) is preferably 1.5 to 5 mm.

The fuel electrode layer 4 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. In addition, as a rare earth element, the rare earth elements (Y etc.) illustrated in the electroconductive support body 2 can be used.

In the fuel electrode layer 4, 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 porosity of the fuel electrode layer 3 is preferably 15% or more, particularly preferably in the range of 20 to 40%, and the thickness thereof is preferably 1 to 30 μm. For example, if the thickness of the fuel electrode layer 4 is too thin, the performance may be deteriorated. If the thickness is too thick, peeling or cracks due to a difference in thermal expansion coefficient between the solid electrolyte layer 5 and the fuel electrode layer 4 described later may occur. May occur.

The solid electrolyte layer 5 uses a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing rare earth elements 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 5 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 fuel cell 1 of the present invention has a solid joint between the solid electrolyte layer 5 and the air electrode layer 7 between the solid electrolyte layer 5 and the air electrode layer 7 described later, and the components of the solid electrolyte layer 5 and the air. The intermediate layer 6 is provided for the purpose of suppressing formation of a reaction layer having a high electrical resistance by reacting with the components of the polar layer 7.

Here, the intermediate layer 6 can be formed with a composition containing Ce (cerium) and other rare earth elements. 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. .

  In addition, the fuel cell 1 of the present invention is characterized in that the porosity of the intermediate layer 6 is 40 to 60% and the average pore diameter is 1 to 3 μm, more preferably the porosity is 50 to 60%, The average pore size is preferably 2 to 3 μm. As a result, the stress of the fuel cell is effected by a large number of pores having an average pore diameter of 1 to 3 μm provided in the intermediate layer due to the difference in thermal expansion of each member constituting the fuel cell 1 and deformation accompanying the reduction treatment. The intermediate layer 6 and the air electrode layer 7 can be prevented from peeling off.

  Although not shown, a bonding layer may be provided between the intermediate layer 6 and the solid electrolyte layer 5 for the purpose of strengthening the bonding between the intermediate layer 6 and the solid electrolyte layer 5. Thereby, the bondability between the bonding layer and the intermediate layer 6 is improved, and the bonding between the intermediate layer 6 and the solid electrolyte layer 5 can be made stronger. In addition, as a joining layer, it is preferable to contain cerium, for example, it can also be set as the same composition as the intermediate | middle layer 6. FIG.

  In providing the bonding layer, it can be provided by simultaneous firing with the solid electrolyte layer 5. In producing a fuel cell having a bonding layer, the intermediate layer 6 is preferably fired at a temperature lower by 200 ° C. or more than the simultaneous firing of the solid electrolyte layer 5 and the bonding layer. The intermediate layer 6 refers to a layer bonded to the first air electrode layer 7 a, and the same applies when a plurality of layers are provided between the solid electrolyte layer 6 and the air electrode layer 7.

The air electrode layer 7 includes a first air electrode layer 7a disposed on the intermediate layer 6 and a second air electrode layer 7b disposed on the first air electrode layer 7a. The air electrode layer 7 (the first air electrode layer 7a and the second air electrode layer 7b) is formed of a conductive ceramic made of a sintered body mainly composed of a so-called ABO ₃ type perovskite complex oxide. preferably is a transition metal perovskite oxide, especially Sr in the a site (strontium) and La (lanthanum) coexist LaSrCoFeO ₃ type oxide (e.g., LaSrCoFeO _3), LaMnO ₃ type oxide (e.g., LaSrMnO _3), LaFeO _At least one of ternary oxides (for example, LaSrFeO ₃ ) and LaCoO ₃ (for example, LaSrCoO ₃ ) is preferable, and LaSrCoFeO ₃ -based oxides have high electrical conductivity at an operating temperature of about 600 to 1000 ° C. Is particularly preferred. In the perovskite oxide, Fe (iron) or Mn (manganese) may exist at the B site together with Co (cobalt).

  Specifically, since the second air electrode layer 7b needs to have gas permeability, the porosity is preferably in a range larger than 40%, particularly in a range of 50 to 70%. The porosity of the polar layer 7a is smaller than that of the second air electrode layer 7b, and can be appropriately set within a range of preferably 30 to 55%. Further, the porosity of the first air electrode layer 7 a is set to be equal to or lower than the porosity of the intermediate layer 6. Thereby, the stress generated in the air electrode layer 7 can be relaxed in the intermediate layer 6. Note that the lower limit of the porosity of the first air electrode layer 7a is 25% from the viewpoint of current collection and bonding strength.

  From the viewpoint of current collection, the thickness of the first air electrode layer 7a is preferably 5 to 50 μm, the thickness of the second air electrode layer 7b is preferably 30 μm to 70 μm, and the thickness as the air electrode layer 7 is 30 to 100 μm. It is preferable that

  Further, an interconnector 9 is laminated on the surface (one flat surface n) opposite to the air electrode layer 7 side of the conductive support 2 via an adhesion layer 8.

Although the interconnector 9 is preferably formed of conductive ceramics, it needs to have reduction resistance and oxidation resistance because it is in contact with the fuel gas (hydrogen-containing gas) and the oxygen-containing gas. . For this reason, lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides) are generally used as conductive ceramics having reduction resistance and oxidation resistance. In particular, the conductive support 2 and the solid electrolyte layer 5 are used. LaCrO ₃ -based oxides are used for the purpose of bringing the coefficient of thermal expansion closer to the above.

  Further, the thickness of the interconnector 9 is preferably 10 to 50 μm from the viewpoint of preventing gas leakage and 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.

  Further, an adhesion layer 8 may be provided between the conductive support 2 and the interconnector 9 in order to reduce a difference in thermal expansion coefficient between the interconnector 9 and the conductive support 2.

The adhesion layer 8 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.

  Although not shown, it is preferable to provide a P-type semiconductor layer on the outer surface (upper surface) of the interconnector 9. By connecting the current collecting member to the interconnector 9 via the P-type semiconductor layer, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and the deterioration of the current collecting performance can be effectively avoided. .

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. In general, the thickness of such a P-type semiconductor layer is preferably in the range of 30 to 100 μm.

  By the way, in the conventional fuel cell, during the production of the fuel cell and the operation of the fuel cell device, due to the difference in thermal expansion of each member constituting the fuel cell 1 and deformation accompanying the reduction treatment, Stress may be generated inside, and the intermediate layer 6 and the air electrode layer 7 (first air electrode layer 7a) may be peeled off, which may reduce the long-term reliability of the fuel cell.

  Therefore, in the fuel cell 1 shown in FIG. 1, the heat of each member constituting the fuel cell 1 is obtained by setting the porosity of the intermediate layer 6 to 40 to 60% and the average pore diameter to 1 to 3 μm. Even when stress is generated inside the fuel cell 1 due to the expansion difference or deformation due to the reduction treatment, the fuel cell 1 has a large number of pores having an average pore diameter of 1 to 3 μm provided in the intermediate layer 6. The stress can be effectively relaxed, and peeling between the intermediate layer 6 and the air electrode layer 7 can be suppressed. Thereby, it can be set as the fuel cell 1 with improved long-term reliability.

  Furthermore, in the fuel cell 1 of the present invention, by making the porosity of the first air electrode layer 7a smaller than the porosity of the second air electrode layer 7b provided on the first air electrode layer 7a, While maintaining a high current collecting property, the bonding area with the intermediate layer 6 can be increased, and the intermediate layer 6 and the air electrode layer 7 can be prevented from being peeled off.

  In the fuel cell 1 of the present invention, the porosity of the first air electrode layer 7a is set to be equal to or less than the porosity of the intermediate layer 6, so that even when the air electrode layer 7 is reduced and contracted during power generation, the intermediate layer 6 can relieve stress, and it can further suppress that the intermediate | middle layer 6 and the air electrode layer 7 produce peeling. Thereby, it can be set as the fuel cell 1 with improved long-term reliability.

  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 using this clay, extrusion molding is performed. A conductive support molded body is prepared and dried. In addition, as the conductive support molded body, a calcined body obtained by calcining the conductive support molded body at 900 to 1000 ° C. for 2 to 6 hours may be 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. The fuel electrode layer slurry is applied on the obtained sheet-shaped solid electrolyte layer molded body to form a laminate molded body in which the fuel electrode layer molded body is formed, and this laminate molded body is formed into the fuel electrode layer molded body. The body is laminated on the conductive support compact with the bottom surface.

  The slurry for the fuel electrode layer may be applied to a predetermined position of the conductive support molded body and dried, and the solid electrolyte layer molded body may be laminated on the conductive support molded body (fuel electrode layer molded body).

  Subsequently, an intermediate layer molded body disposed between the solid electrolyte layer 5 and the air electrode layer 7 is formed.

For example, CeO ₂ powder in which GdO _1.5 is dissolved is heat-treated at 800 to 900 ° C. for 2 to 6 hours, and then wet pulverized to adjust the aggregation degree to 5 to 35, thereby forming an intermediate layer molded body. Prepare raw material powder for use. The wet crushing is desirably ball milled for 10 to 20 hours using a solvent. The same applies when the intermediate layer 6 is formed of CeO ₂ powder in which SmO _1.5 is dissolved.

  Then, an intermediate layer slurry is prepared by adding toluene as a solvent and a pore former having an average particle size of 1 to 3 μm so as to have a predetermined porosity to the raw material powder of the intermediate layer molded body whose cohesion degree is adjusted. And this slurry is applied onto the solid electrolyte layer molded body to produce an intermediate layer molded body. In addition, a sheet-like intermediate layer molded body may be prepared and laminated on the solid electrolyte layer molded body. In addition, as a pore making material, you may use what is generally known.

Subsequently, a material for the interconnector 9 (for example, LaCrMgO ₃ oxide powder), an organic binder, and a solvent are mixed to prepare a slurry, and an interconnector sheet is prepared.

Subsequently, an adhesion layer molded body positioned between the conductive support 2 and the interconnector 9 is formed. For example, ZrO ₂ in which Y is dissolved and NiO are mixed and dried so that the volume ratio is in the range of 40:60 to 60:40, and an organic binder or the like is added to adjust the slurry for the adhesion layer. The adjusted adhesion layer slurry is applied to the interconnector sheet to form an adhesion layer molded body, and the surface on the adhesion layer molded body side is laminated on the conductive support molded body.

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

  In addition, when providing a joining layer between the intermediate | middle layer 6 and the solid electrolyte layer 5, when comprising a joining layer from the same composition as the intermediate | middle layer 6, it is the same as the intermediate | middle layer molded object adjusted by said method. Raw material powder and toluene are added to prepare a bonding layer slurry, which is applied onto the solid electrolyte layer formed body to form a bonded layer formed body. Subsequently, an adhesive layer molded body is laminated on the conductive support molded body to produce a laminated molded body. The laminated molded body is debindered and co-fired at 1400 to 1600 ° C. for 2 to 6 hours in an oxygen atmosphere. Subsequently, the intermediate layer 6 is laminated on the upper surface of the bonding layer by applying the above-mentioned slurry for the intermediate layer and then baking at a temperature 200 ° C. lower than the temperature at the time of the simultaneous baking. be able to.

  Subsequently, when the air electrode layer 7 is composed of one layer when the air electrode layer 7 is provided, for example, a slurry containing a LaCoO 3 oxide powder, a solvent, and a pore former is screen-printed on the solid electrolyte layer 5. After coating and drying, baking is performed at 1100 to 1200 ° C. for 1 to 3 hours. In addition, as a pore making material, the thing of a fibrous form which has a magnitude | size (diameter) of 5-20 micrometers can be used, for example, and 20 mass% or less so that the air electrode layer 7 may become the target porosity. It can add suitably in the range.

On the other hand, when the air electrode layer 7 is composed of two layers, a slurry containing, for example, a LaSrCoFeO ₃ oxide powder, a solvent, and a pore former, which is a material of the first air electrode layer 7a, is solid. It is applied on the electrolyte layer 5 by screen printing and dried.

Subsequently, a slurry containing, for example, LaSrCoFeO ₃ -based oxide powder, a solvent, and a pore former, which is a material of the second air electrode layer 7b, is screen-printed on the first air electrode layer molded body. After coating and drying, baking is performed at 1100 to 1200 ° C. for 1 to 3 hours. As the pore former, the above-described pore former can be appropriately used according to the intended porosity of the first air electrode layer 7a and the second air electrode layer 7b. The fuel cell 1 can be manufactured through the above steps.

  In the fuel cell 1 of the present invention produced as described above, the porosity of the intermediate layer 6 is 40 to 60% and the average pore diameter in the intermediate layer 6 is 1 to 3 μm. Separation from the air electrode layer 7 can be suppressed.

  In detecting the presence or absence of separation between the intermediate layer 6 and the air electrode layer 7, the fuel cell is cut so that the interface between the intermediate layer 6 and the air electrode layer 7 in the fuel cell 1 can be seen. The cut surface was confirmed by photographing with a scanning electron microscope (SEM).

  In confirming the presence or absence of peeling, the fuel cell 1 may be cut at any site, and it is preferable to check 3 to 10 cut surfaces per fuel cell. By setting the number of cut surfaces to be observed to three or more, accuracy can be improved in detecting the presence or absence of peeling.

  In the present invention, the pore diameter is defined as the diameter of a circle when it is assumed that the value obtained by image analysis of the pore area in the cross section is a circle. In addition, the average pore diameter is the average value of the pore diameters of any 10 pores.

  Specifically, the fuel battery cell 1 is cut and the cut surface is photographed by SEM. Ten arbitrary pores in the intermediate layer 6 of the photographed image are selected. The area of each selected pore is obtained, the shape of the pore is assumed to be a circle, the diameter of the circle is calculated from the area of the pore, and the pore diameter of each pore is obtained. The average pore diameter is obtained by averaging the 10 pore diameters in each obtained pore.

  The porosity can be obtained by cutting the fuel battery cell 1, photographing the cut surface with an SEM, binarizing the photographed image, and dividing the ratio indicating the pores by the entire area.

  FIG. 2 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 13, and FIG. The side view which shows the stack | stuck apparatus 11 schematically, (b) is a partial enlarged plan view of the cell stack apparatus 11 of (a), and extracts and shows the part enclosed with the dotted-line frame shown by (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 11, each fuel battery cell 1 is arranged via a current collecting member 14 to constitute a cell stack 12, and the lower end of each fuel battery cell 1 is fueled to the fuel battery cell 1. It is fixed to a manifold 15 for supplying gas by an adhesive such as a glass sealing material. Further, an elastically deformable conductive member 16 having a lower end fixed to the manifold 15 is provided so as to sandwich the cell stack 12 from both ends in the arrangement direction of the fuel cells 1 via the current collecting members 13.

  Further, in the conductive member 16 shown in FIG. 2, a current for drawing out a current generated by power generation of the cell stack 12 (fuel cell 1) in a shape extending outward along the arrangement direction of the fuel cells 1. A drawer portion 17 is provided.

  Here, in the cell stack device 11 of the present invention, by configuring the cell stack 12 using the fuel cell 1 described above, the porosity of the intermediate layer 6 is 40 to 60%, and the intermediate layer 6 Since the average pore diameter of the fuel cell 1 is 1 to 3 μm, the stress of the fuel cell 1 can be effectively relieved by a large number of pores having an average pore diameter of 1 to 3 μm provided in the intermediate layer 6. Peeling between the layer 6 and the air electrode layer 7 can be suppressed. Thereby, it can be set as the fuel cell 1 with improved long-term reliability.

  FIG. 3 is an external perspective view showing an example of the fuel cell module 18 in which the cell stack device 11 of the present invention is housed in a housing container. The cell shown in FIG. The stack device 11 is accommodated.

  In order to obtain fuel gas used in the fuel cell 1, a reformer 20 for reforming raw fuel such as natural gas or kerosene to generate fuel gas is disposed above the cell stack 12. ing. The fuel gas generated by the reformer 20 is supplied to the manifold 15 via the gas flow pipe 21 and supplied to the fuel gas flow path 3 provided inside the fuel battery cell 1 via the manifold 15. The

  FIG. 3 shows a state in which a part (front and rear surfaces) of the storage container 19 is removed and the cell stack device 11 and the reformer 20 housed inside are taken out rearward. Here, in the fuel cell module 18 shown in FIG. 3, the cell stack device 11 can be slid and stored in the storage container 19. The cell stack device 11 may include the reformer 20.

  Further, in FIG. 3, the oxygen-containing gas introduction member 22 provided inside the storage container 19 is disposed between the cell stacks 12 juxtaposed to the manifold 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 (one end) toward the upper end (the other end). The temperature of the fuel cell 1 can be increased by burning the fuel gas and the oxygen-containing gas discharged from the fuel gas channel 3 of the fuel cell 1 on the upper end side of the fuel cell 1. The activation of the cell stack device 11 can be accelerated. Further, by burning the fuel gas and the oxygen-containing gas discharged from the fuel gas flow path of the fuel cell 1 on the upper end side of the fuel cell 1, the upper side of the fuel cell 1 (cell stack 12). It is possible to efficiently warm the reformer 20 disposed in the. Thereby, the reforming reaction can be efficiently performed in the reformer 20.

  Furthermore, in the fuel cell module 18 of the present invention, since the cell stack device 11 configured using the fuel cell 1 having improved long-term reliability is stored in the storage container 19, the long-term reliability is improved. The fuel cell module 18 can be obtained.

  FIG. 4 is an exploded perspective view showing an example of the fuel cell device of the present invention in which the fuel cell module 18 shown in FIG. 3 and an auxiliary machine for operating the fuel cell stack device 11 are housed in an outer case. FIG. In FIG. 4, a part of the configuration is omitted.

  The fuel cell device 23 shown in FIG. 4 divides the inside of an exterior case made up of columns 24 and an exterior plate 25 into upper and lower portions by a partition plate 26, and a module storage chamber 27 for storing the above-described fuel cell module 18 on the upper side thereof. The lower side is configured as an auxiliary equipment storage chamber 28 for storing auxiliary equipment for operating the fuel cell module 18. It should be noted that auxiliary equipment stored in the auxiliary equipment storage chamber 28 is omitted.

  In addition, the partition plate 26 is provided with an air circulation port 29 for flowing the air in the auxiliary machine storage chamber 28 to the module storage chamber 27 side, and a part of the exterior plate 25 constituting the module storage chamber 27 An exhaust port 30 for exhausting the air in the module storage chamber 27 is provided.

  In such a fuel cell device 23, as described above, the fuel cell module 18 capable of improving the long-term reliability is housed in the module housing chamber 27, whereby the fuel having improved long-term reliability. The battery device 23 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 paper of the present invention.

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 to a volume ratio of 48% by volume of NiO and 52% by volume of 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 conductive support molded body. Sample No. In No. 1, the volume ratio of the Y ₂ O ₃ powder after calcination and reduction was such that NiO was 45% by volume and Y ₂ O ₃ was 55% by volume.

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 sheet for a solid electrolyte layer having a thickness of 30 μm 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 layer slurry was applied to form a fuel electrode layer molded body, and the fuel electrode layer molded body side surface was laminated at a predetermined position of the conductive support molded body to produce a laminated molded body.

  Subsequently, the laminated molded body in which the molded bodies were laminated as described above was calcined at 1000 ° C. for 3 hours to produce a laminated calcined body.

Next, a composite oxide containing 85 mol% of CeO ₂ and 15 mol% of another rare earth element oxide (GdO _1.5 ) is pulverized by a vibration mill or a ball mill using isopropyl alcohol (IPA) as a solvent. Then, calcination was performed at 900 ° C. for 4 hours, and pulverization was performed again with a ball mill to adjust the degree of aggregation of the ceramic particles, thereby obtaining a raw material powder for an intermediate layer. A laminated calcined body obtained by adding an acrylic binder, toluene, and a pore former so as to have the porosity shown in Table 1 and mixing them to obtain a slurry for an intermediate layer produced by mixing. On the solid electrolyte layer calcined body, it was applied by a screen printing method to produce an intermediate layer molded body.

Next, a slurry for an adhesion layer was prepared by mixing NiO powder having an appropriately adjusted particle size, ZrO ₂ powder in which 8 mol% of Y ₂ O ₃ was dissolved, an organic binder, and a solvent.

Subsequently, an interconnector sheet having a thickness of 30 μm was prepared by a doctor blade method using an interconnector slurry obtained by mixing a LaCrO ₃ oxide, an organic binder, and a solvent. The surface of the interconnector sheet coated with the above-mentioned adhesion layer slurry is coated with the adhesion layer slurry, and the conductive electrode layer molded body and the solid electrolyte layer molded body are not formed. It laminated | stacked on the flat part of the other side of a support body molded object.

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

Next, sample No. 1 in which the air electrode layer has a single layer structure is used. In preparing No. 9, a mixed liquid composed of LaSrCoFeO ₃ powder having an average particle diameter of 2 μm and isopropyl alcohol was prepared, applied onto the solid electrolyte layer of the laminated sintered body by a screen printing method, and dried.

Sample No. 2 having a two-layered air electrode layer was used. In producing 1 to 8 and 10, first, a first air electrode layer was prepared as a mixed liquid composed of LaSrCoFeO ₃ powder having an average particle diameter of 2 μm, isopropyl alcohol, and a pore former, and a laminated sintered body. On this solid electrolyte layer, it apply | coated and dried by the screen printing method, and the 1st air electrode layer molded object was formed. Subsequently, the second air electrode layer was prepared by preparing a mixed liquid composed of LaSrCoFeO ₃ powder having an average particle diameter of 2 μm, isopropyl alcohol, and a pore former, and applied to the first air electrode layer by a screen printing method and dried. Thus, a second air electrode layer molded body was formed. Thereafter, these were fired at 1150 ° C. for 2 hours. The pore former was appropriately used so as to have the porosity of each sample shown in Table 1.

  The size of the produced fuel cell is 25 mm × 200 mm, the thickness of the conductive support (thickness between the flat surfaces n) is 2 mm, the porosity is 35%, the thickness of the fuel electrode layer is 10 μm, and the porosity is 24%. The thickness of the first air electrode layer was 20 μm, the thickness of the second air electrode layer was 50 μm, and the relative density of the solid electrolyte layer was 97%. In addition, sample No. which an air electrode layer consists of only one layer. In No. 9, the thickness of the air electrode layer was 70 μm.

  Here, 10 fuel cells are produced for each sample, and cross sections of arbitrary three portions including the intermediate layer and the air electrode layer are observed with a scanning electron microscope. The presence or absence of peeling from the extreme layer was confirmed.

From the results of Table 1, sample No. which is outside the scope of the present invention. In 1, 2, and 10, peeling of the intermediate layer and the air electrode occurred in 9 or more of 10 fuel cells.
On the other hand, sample no. In 3 , 5 to 8 , the number of the fuel cells in which the intermediate layer and the air electrode layer were peeled was 3 or less.

  Sample No. 1 in which the porosity of the first air electrode layer is smaller than the porosity of the second air electrode layer and is not more than the porosity of the intermediate layer. In 3 and 5, the number of the fuel cells in which the intermediate layer and the air electrode layer were peeled was 1 or less.

  Furthermore, the porosity of the intermediate layer is 50 to 60%, and the average pore diameter in the intermediate layer is 2 to 3 μm. In 6-8, peeling did not arise in the intermediate | middle layer and the air electrode layer.

  Thereby, it was found that the porosity of the intermediate layer is 40 to 60%, and that the average pore diameter in the intermediate layer is 1 to 3 μm, thereby suppressing the separation between the intermediate layer and the air electrode layer. .

  Further, by making the porosity of the first air electrode layer smaller than the porosity of the second air electrode layer and not more than the porosity of the intermediate layer, it is possible to further suppress the separation between the intermediate layer and the air electrode layer. I knew it was possible.

1: Fuel cell 2: Conductive support 3: Fuel gas flow path 4: Fuel electrode layer 5: Solid electrolyte layer 6: Intermediate layer 7: Air electrode layer 7a: First air electrode layer 7b: Second air electrode layer 8: Adhesion layer 9: Interconnector 11: Cell stack device 18: Fuel cell module 23: Fuel cell device

Claims (5)

A fuel battery cell comprising an interconnector on the surface of a conductive support, and a power generation unit in which a fuel electrode layer, a solid electrolyte layer, an intermediate layer, and an air electrode layer are laminated in this order adjacent to the interconnector Because
The porosity of the intermediate layer is 40 to 60%, and the average pore diameter in the intermediate layer is 1 to 3 μm,
The air electrode layer has a first air electrode layer disposed on the intermediate layer and a second air electrode layer disposed on the first air electrode layer;
Porosity of the first cathode layer is smaller than the porosity of the second cathode layer, and Ri porosity der following the intermediate layer,
The fuel cell according to claim 1, wherein the porosity of the intermediate layer is smaller than the porosity of the second air electrode layer . 2. The fuel cell according to claim 1, wherein the porosity of the first air electrode layer is 30 to 55%, and the porosity of the second air electrode layer is 50 to 70%. A fuel cell according to claim 1 or 2 , wherein a plurality of the fuel cells are arranged in a standing state via a current collecting member, and a cell stack electrically connected in series,
A cell stack device comprising a manifold for fixing a lower end portion of the fuel cell and supplying fuel gas to the fuel cell. A fuel cell module comprising the cell stack device according to claim 3 stored in a storage container. 5. A fuel cell device comprising: the fuel cell module according to claim 4; and an auxiliary machine for operating the fuel cell module.

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