JP2005166527A - Fuel battery cell and fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery cell and a fuel battery, in which internal and external gas interception can be surely carried out, and which are high in power generation performance, even at a comparatively low temperature of 700 to 800°C. <P>SOLUTION: This is the fuel battery cell 33 in which at least a dense solid electrolyte 33c and a porous oxygen side electrode 33d are sequentially installed at one side main face of a porous support substrate 33a having a gas flow-passage 34, and in which an minute interconnector 33f is installed at the other side main face, in which the solid electrolyte 33c formed at the one side main face of the support substrate 33a is extended and installed up to the interconnector 33f end face formed at the other side main face of the support substrate 33a via a side face of the support substrate 33a; and the solid electrolyte 33c is composed of zirconium oxide with which scandium is made into a solid solution. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell and a fuel cell, and in particular, at least a dense solid electrolyte and a porous outer electrode are sequentially provided on one side main surface of a support substrate, and a dense interconnector is provided on the other side main surface. The present invention relates to a fuel cell and a fuel cell.

  FIG. 3 shows a fuel cell 1 of a conventional solid oxide fuel cell. The fuel cell 1 has a flat inner side that also serves as a porous support having a plurality of gas flow paths 3 in the axial direction. A dense solid electrolyte 1b and an outer electrode 1c made of porous conductive ceramics are sequentially provided on the outer peripheral surface of the electrode 1a. The inner electrode 1a exposed from the solid electrolyte 1b and the outer electrode 1c has an outer side. An interconnector 1d is provided so as not to be connected to the electrode 1c, and is electrically connected to the inner electrode 1a. (See Patent Document 1).

  In such a fuel cell 1, by making the shape of the fuel cell 1 flat, the area of the power generation unit per fuel cell 1 can be increased, and the amount of power generation can be increased.

  The fuel cell is configured by storing a plurality of the fuel cells 1 in a storage container. For example, an oxygen-containing gas is supplied into the inner electrode 1a through an oxygen gas injection pipe 5, and a fuel gas (hydrogen) is supplied to the outer electrode 1c. To generate electricity at about 1000 ° C.

  A portion where the inner electrode 1a, the solid electrolyte 1b, and the outer electrode 1c of the fuel cell 1 overlap each other is a power generation unit, and the current generated in the power generation unit uses the inner electrode 1a as a current path and passes through an interconnector 1d. It is connected to another fuel cell 1.

In this fuel cell, ZrO ₂ (YSZ) containing Y ₂ O ₃ is used as the solid electrolyte 1b. Recently, ZrO ₂ containing Sc ₂ O ₃ is also known as a solid electrolyte material. (See Patent Document 2).

As a method for producing a fuel cell, it is conventionally known that the inner electrode 1a and the solid electrolyte 1b are formed by simultaneous firing. This co-firing method is a very simple process, has a small number of manufacturing steps, and is advantageous for cost reduction.
JP-A 63-261678 Japanese Patent Application Laid-Open No. 06-1116026

  However, even such a fuel cell 1 has a problem that the power generation performance obtained is not sufficient and is still low. That is, in the fuel cell 1, the power generation per fuel cell 1 is reduced by reducing the thickness of the solid electrolyte 1b, the inner electrode 1a, the current path, and the width of the inner electrode 1a. Although the amount can be increased, stress concentrates on the curved side surface of the fuel cell 1 having a large curvature. For example, a dense solid electrolyte positioned on the side surface of the fuel cell 1 during firing or power generation There was a problem that cracks were likely to occur in 1b.

  Even when the side surface of the inner electrode 1a is not a curved surface but a flat surface, there is a problem in that cracks are likely to occur in the solid electrolyte at the corner formed between the side surface and the main surface.

  That is, in the fuel cell 1, when the stress is most likely to be concentrated on the curved side surface having a large curvature (small curvature radius) of the fuel cell 1 and the stress exceeds the strength of the solid electrolyte 1b located on the side surface, Cracks occur in the solid electrolyte 1b on the side surface, and the gas inside and outside the fuel cell 1 cannot be shut off, and the power generation performance of the fuel cell 1 is deteriorated.

In addition, since it becomes impossible to shut off the gas inside and outside the fuel cell 1, the difference in oxygen partial pressure between the inside and outside of the fuel cell 1 that is the basis of power generation is reduced, so that the amount of power generation also decreases in other fuel cells 1. In addition, since the solid electrolyte is made of ZrO ₂ (YSZ) containing Y ₂ O ₃ , when the operating temperature is lowered from 700 ° C. to 800 ° C., the electric conductivity of the solid electrolyte is low, so the power generation performance is lowered. There was a problem.

  An object of the present invention is to provide a fuel cell and a fuel cell that can reliably shut off gas inside and outside and have high power generation performance even at a relatively low temperature of 700 to 800 ° C.

  The fuel cell of the present invention is provided with at least a dense solid electrolyte and a porous outer electrode sequentially on one main surface of a porous support substrate having a gas flow path, and a dense interconnector on the other main surface. A solid electrolyte formed on one main surface of the support substrate and extending to a connector end surface formed on the other main surface of the support substrate via a side surface of the support substrate. In addition, the solid electrolyte is made of zirconium oxide in which scandium is dissolved.

In such a fuel cell, since the solid electrolyte is formed of zirconium oxide in which scandium is dissolved, the strength is higher than that of ZrO ₂ (YSZ) containing Y ₂ O ₃ conventionally used. Even when it is formed on the thin side surface of the support substrate that is likely to be strongly generated, it is possible to prevent the occurrence of cracks in the solid electrolyte, and to surround the porous support substrate with a dense interconnector and a dense solid electrolyte. Even if the thickness of the support substrate is reduced, the width is increased, and the thickness of the solid electrolyte is reduced, the generation of cracks in the solid electrolyte can be prevented, and the gas inside and outside the fuel cell can be effectively shut off. In addition, zirconium oxide stabilized by dissolving scandium has higher conductivity in the temperature range of 700 to 800 ° C. than YSZ, and thus power generation performance can be improved.

  Scandium is preferably dissolved in an amount of 3 to 15 mol%. Thereby, the ionic conductivity of a solid electrolyte becomes high, and electric power generation performance improves. In particular, it is desirable to dissolve 8 to 12 mol%.

  The fuel cell of the present invention is characterized in that the thickness between the main surfaces of the support substrate is 2 to 5 μm. In such a thin support substrate, the stress on the side surface tends to increase, and the strength of the solid electrolyte is required. Therefore, the present invention can be suitably used.

  Furthermore, the fuel battery cell of the present invention is characterized in that the side surface of the support substrate is a curved surface that protrudes outward. By making the side surface of the support substrate a curved surface, the stress generated in the solid electrolyte formed on the side surface of the support substrate can be reduced. When the side surface of the support substrate is a curved surface having a curvature radius of 1 to 3 μm, the stress generated in the solid electrolyte increases as the curvature radius of the side surface of the support substrate decreases, so that the present invention can be suitably used. .

  In the fuel cell of the present invention, a fuel-side electrode, a solid electrolyte, and an oxygen-side electrode are sequentially formed on one side main surface of a support substrate mainly composed of a rare earth element oxide and Ni and / or NiO. The rare earth element of the support substrate is at least one of Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr.

In such a fuel cell, the rare earth oxide in the support substrate hardly causes solid solution or reaction with the iron group metal or its oxide during firing or power generation. Furthermore, this rare earth oxide is much smaller than the thermal expansion coefficient (about 10.8 × 10 ⁻⁶ / ° C.) of zirconia stabilized by solid solution of the rare earth element in the solid electrolyte and the fuel electrode. ₂ O ₃ and Yb ₂ O ₃ have a thermal expansion coefficient of about 8.14 × 10 ⁻⁶ / ° C. Therefore, by controlling the content ratio of the rare earth oxide, the thermal expansion coefficient of the support substrate is changed to the solid electrolyte layer. And the thermal expansion coefficient of the fuel electrode can be brought close to, and the generation and separation of cracks due to the difference in thermal expansion can be effectively suppressed.

  The fuel cell according to the present invention is characterized in that a plurality of the fuel cells are accommodated in a storage container. As described above, the fuel battery cell of the present invention can reliably shut off the gas inside and outside, and has high power generation performance even at a relatively low temperature of 700 to 800 ° C. A fuel cell excellent in power generation performance and durability can be provided by preventing problems such as lowering.

  Furthermore, the fuel cell of the present invention is used for distributed power generation. For example, a fuel cell used for a household fuel cell system having a power generation performance of about 1 kW or a fuel cell system for a store having a power generation performance of 7 kW or less is small in size and the support substrate itself is also thin. Since the stress generated on the side surface of the substrate tends to increase, the present invention can be suitably used.

In the fuel cell of the present invention, the solid electrolyte is formed of zirconium oxide stabilized by dissolving scandium, so that the strength is higher than that of ZrO ₂ (YSZ) containing Y ₂ O ₃ which has been conventionally used. For example, even when it is formed on a thin side surface of a support substrate where stress is likely to be generated, cracks in the solid electrolyte can be prevented, gas inside and outside the fuel cell can be effectively blocked, and scandium can be solidified. Zirconium oxide that has been melted and stabilized has higher electrical conductivity in the temperature range of 700 to 800 ° C. than YSZ, and therefore can improve power generation performance.

  The fuel cell of the present invention has a plate-like cross section as shown in FIG. 1, and a porous fuel side electrode 33b on one main surface of a columnar porous conductive support substrate 33a as a whole. In addition, a dense solid electrolyte 33c and an oxygen side electrode 33d made of porous conductive ceramics are sequentially laminated, and a bonding layer 33e, a lanthanum-chromium-based oxidation are formed on the other main surface of the support substrate 33a opposite to the oxygen side electrode 33d. An interconnector 33f made of a material and a current collecting film 33g made of a P-type semiconductor material are formed.

  A plurality of linear gas passages 34 are formed in the support substrate 33a so as to penetrate in the axial direction.

  That is, the fuel cell 33 includes an end m provided in both ends in the width direction in an arc shape and a pair of flat portions a connecting the end m, and the pair of flat portions a. Are flat and formed substantially in parallel. The shape of the support substrate 33a that governs the shape of the fuel battery cell 33 also has a pair of flat main surfaces and a curved side surface connecting these main surfaces. One of the flat portions a of the fuel cell 33 is configured by forming a bonding layer 33e, an interconnector 33f, and a current collecting film 33g on the other main surface of the support substrate 33a. A fuel side electrode 33b, a solid electrolyte 33c, and an oxygen side electrode 33d are formed on one main surface of 33a.

  Moreover, it is desirable that the major axis dimension (distance between the ends m direction) of the support substrate 33a is 15 to 35 mm, and the minor axis dimension (distance between the flat portions a) is 2 to 5 mm. The side surface of the support substrate 33a has a curved shape that protrudes outward, and the side surface of the support substrate 33a has a curved shape with a curvature radius of 1 to 3 μm.

  The support substrate 33a is mainly composed of one or more rare earth element oxides selected from Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm and Pr and Ni and / or NiO. It is desirable that

The bonding layer 33e formed between the support substrate 33a and the interconnector 33f is composed mainly of ZrO ₂ containing Ni and / or NiO and a rare earth element. The Ni conversion amount of the Ni compound in the bonding layer 33e is preferably 35 to 80% by volume, more preferably 50 to 70% by volume, based on the total amount. By setting Ni to 35% by volume or more, the conductive path due to Ni increases, the conductivity of the bonding layer 33e improves, and the voltage drop decreases. Moreover, by making Ni 80 volume% or less, the thermal expansion coefficient difference between the support substrate 33a and the interconnector 33f can be made small, and generation | occurrence | production of the crack of both interface can be suppressed.

  In addition, the thickness of the bonding layer 33e is preferably 20 μm or less, and more preferably 10 μm or less from the viewpoint that the potential drop is reduced.

The thermal expansion coefficient of the medium rare earth element or heavy rare earth element oxide is smaller than the thermal expansion coefficient of ZrO ₂ containing Y ₂ O ₃ of the solid electrolyte 33c, and the thermal expansion coefficient of the support substrate 33a as a cermet material with Ni. Can be brought close to the thermal expansion coefficient of the solid electrolyte 33c, and cracking of the solid electrolyte 33c and separation of the solid electrolyte 33c from the fuel-side electrode 33b can be suppressed. By using a heavy rare earth element oxide having a small thermal expansion coefficient, it is possible to increase the amount of Ni in the support substrate 33a and to increase the electric conductivity of the support substrate 33a. desirable.

  The light rare earth elements La, Ce, Pr, and Nd oxides may be medium rare earth elements, heavy rare earth elements as long as the sum of the thermal expansion coefficients of the rare earth element oxides is less than the thermal expansion coefficient of the solid electrolyte 33c. There is no problem even if it is contained in addition to the elements.

  Moreover, the raw material cost can be significantly reduced by using a complex rare earth element oxide containing a plurality of inexpensive rare earth elements in the course of purification. Also in that case, it is desirable that the thermal expansion coefficient of the complex rare earth element oxide is less than the thermal expansion coefficient of the solid electrolyte 33c.

  Further, it is desirable to provide a current collecting film 33g made of a P-type semiconductor, for example, a transition metal perovskite oxide, on the surface of the interconnector 33f. When a metal current collecting member is disposed directly on the surface of the interconnector 33f to collect current, the potential drop increases due to non-ohmic contact. In order to make ohmic contact and reduce the potential drop, it is necessary to connect the current collector film 33g made of a P-type semiconductor to the interconnector 33f, and it is desirable to use a transition metal perovskite oxide that is a P-type semiconductor. . The transition metal perovskite oxide is preferably made of at least one of a lanthanum-manganese oxide, a lanthanum-iron oxide, a lanthanum-cobalt oxide, or a composite oxide thereof. In particular, the current collecting film 33g is preferably made of an oxygen-side electrode material.

The fuel side electrode 33b provided on the main surface of the support substrate 33a is composed of Ni and ZrO _{2 in} which a rare earth element is dissolved. The thickness of the fuel side electrode 33b is desirably 1 to 30 μm. By setting the thickness of the fuel side electrode 33b to 1 μm or more, a three-layer interface as the fuel side electrode 33b is sufficiently formed. Further, by setting the thickness of the fuel side electrode 33b to 30 μm or less, it is possible to prevent interface peeling due to a difference in thermal expansion from the solid electrolyte 33c.

  The thickness of the solid electrolyte 33c is desirably 5 to 100 μm. Gas permeation can be prevented by setting the thickness of the solid electrolyte 33c to 5 μm or more. Moreover, the increase in a resistance component can be suppressed by making the thickness of the solid electrolyte 33c into 100 micrometers or less. In particular, in order to improve the power generation capability of the fuel cell 33, it is desirable that the thickness of the solid electrolyte 33c formed on one main surface of the support substrate 33a is 20 μm or less. On the other hand, the thinner the solid electrolyte 33c is, the easier it is for cracks to occur, so that the present invention can be suitably used.

  In the present invention, in order to increase the strength and increase the power generation performance even in the temperature range of 700 to 800 ° C., the solid electrolyte is formed from zirconium oxide stabilized by dissolving scandium. Scandium is preferably dissolved in zirconium oxide in an amount of 3 to 15 mol%. When the amount of the solid solution is less than 3 mol%, the ionic conductivity is lowered and the power generation performance is lowered. Even if the amount of the solid solution is more than 15 mol%, the ionic conductivity is lowered and the power generation performance is lowered. In particular, when the solid solution amount is 8 to 12 mol%, the ionic conductivity is increased, and the power generation performance is improved. In addition to Sc, it is desirable to contain 0.5 to 2 mol% of cerium oxide from the viewpoint of further increasing the ionic conductivity.

  The stabilized zirconia ceramics forming the solid electrolyte layer 33 is desirably dense with a relative density (according to Archimedes method) of 93% or more, particularly 95% or more, from the viewpoint of preventing gas permeation.

The oxygen side electrode 33d is made of a lanthanum-manganese oxide, lanthanum-iron oxide, lanthanum-cobalt oxide of a transition metal perovskite oxide, or at least one porous oxide of a composite oxide thereof. It is composed of conductive ceramics. The oxygen side electrode 33d is preferably a (La, Sr) (Fe, Co) O ₃ system in terms of high electrical conductivity in the middle temperature range of about 800 ° C. The thickness of the oxygen side electrode 33d is preferably 30 to 100 μm from the viewpoint of current collection.

  The interconnector 33f is a dense body for preventing leakage of fuel gas and oxygen-containing gas inside and outside the support substrate 33a, and the inner and outer surfaces of the interconnector 33f are in contact with the fuel gas and oxygen-containing gas. It has reduction resistance and oxidation resistance.

  The thickness of the interconnector 33f is desirably 30 to 200 μm. By setting the thickness of the interconnector 33f to 30 μm or more, gas permeation can be completely prevented, and by setting it to 200 μm or less, an increase in resistance component can be suppressed.

For example, a bonding layer made of Ni and ZrO ₂ or Y ₂ O ₃ may be interposed between the end of the interconnector 33f and the end of the solid electrolyte 33c in order to improve the sealing performance.

  In the fuel cell 33 of the present invention, the dense solid electrolyte 33c is formed not only on one side main surface of the support substrate 33a but also on the other side main surface via the side surface of the support substrate 33a. That is, it extends to the other principal surface so as to form both end portions m, and is joined to the interconnector 33e. In addition, in order to relieve the thermal stress which generate | occur | produces with the heating and cooling accompanying electric power generation, it is desirable for the edge part m to become the curved surface shape which becomes convex outside.

  It is desirable that the thickness of the solid electrolyte 33c provided on the side surface of the support substrate 33a is thicker than the thickness of the solid electrolyte 33c which is a dense body provided on the one side main surface of the support substrate 33a. In such a fuel cell 33, by increasing the thickness of the solid electrolyte 33c provided on the side surface of the conductive support 33a where stress is easily concentrated, the strength of the dense body can be increased. Generation of cracks in the solid electrolyte 33c provided on the side surface of the support substrate 33a can be prevented.

  The manufacturing method of the fuel cell 33 as described above will be described. First, rare earth element oxide powder excluding La, Ce, Pr, and Nd elements and Ni and / or NiO powder are mixed, and a conductive support substrate material in which an organic binder and a solvent are mixed is extruded into this mixed powder. It shape | molds and produces a plate-shaped support substrate molded object, This is dried and degreased.

Moreover, a sheet-like solid electrolyte molded body is produced using a solid electrolyte material in which a rare earth element-dissolved ZrO ₂ powder, an organic binder, and a solvent are mixed.

Next, Ni and / or NiO powder, ZrO ₂ powder in which a rare earth element is dissolved, an organic binder, and a solvent are mixed, and a slurry to be a fuel-side electrode 33b is prepared as one of the solid electrolyte molded bodies. The fuel electrode coating film is formed on one surface of the solid electrolyte compact.

  Next, the sheet-shaped solid electrolyte molded body and the fuel-side electrode molded body are laminated and wound around the support substrate molded body so that the fuel-side electrode molded body comes into contact with the support substrate molded body.

  Next, a sheet-like interconnector molded body is produced using an interconnector material in which a lanthanum-chromium oxide powder, an organic binder, and a solvent are mixed.

Further, a sheet-like joining layer molded body is prepared using a slurry in which Ni and / or NiO powder, ZrO ₂ powder in which a rare earth element is dissolved, an organic binder, and a solvent are mixed.

  Next, the interconnector molded body and the bonding layer molded body are laminated, and the laminated body is laminated so that the bonding layer molded body side is in contact with the exposed support substrate molded body side.

  Thus, a laminated molded body in which a fuel-side electrode molded body and a solid electrolyte molded body are sequentially laminated on one main surface of the support substrate molded body, and a bonding layer molded body and an interconnector molded body are laminated on the other main surface. Is made. In addition, each molded object can be produced by sheet | seat shaping | molding by a doctor blade, printing, slurry dip, spraying by spraying, etc., or may be produced by a combination thereof.

  Next, the multilayer molded body is degreased and cofired at 1300 to 1600 ° C. in an oxygen-containing atmosphere.

  Next, a transition metal perovskite oxide powder, which is a P-type semiconductor, and a solvent are mixed to prepare a paste, and the laminate is immersed in this paste, and the oxygen side is placed on the surfaces of the solid electrolyte 33b and the interconnector 33f. The fuel cell 33 of the present invention can be manufactured by forming the electrode molded body and the current collector film molded body by dipping or spraying directly and baking at 1000 to 1300 ° C.

  In addition, since the Ni component in the support substrate 33a, the fuel side electrode 33b, and the bonding layer 33e is NiO by firing in the oxygen-containing atmosphere, the fuel battery cell 33 is subsequently reduced from the support substrate 33a side. Then, NiO is reduced at 800 to 1000 ° C. Further, this reduction process may be performed during power generation.

  As shown in FIG. 2, the cell stack has a plurality of fuel cells 33 arranged at a predetermined interval, and a metal felt and / or a metal between one fuel cell 33 and the other fuel cell 33. A current collecting member 43 made of a plate is interposed, and a support substrate 33a of one fuel battery cell 33 is connected via a bonding layer 33e, an interconnector 33f, a current collecting film 33g, and a current collecting member 43 provided on the support substrate 33a. The other fuel cell 33 is electrically connected to the oxygen side electrode 33d.

  The current collecting member 43 is preferably made of at least one of Pt, Ag, Ni-base alloy, and Fe—Cr steel alloy from the viewpoint of heat resistance, oxidation resistance, and electrical conductivity. Reference numeral 42 denotes a conductive member for connecting the fuel cells in series.

  The fuel cell of the present invention is configured by storing the cell stack of FIG. 2 in a storage container. This storage container is provided with an introduction pipe for introducing a fuel gas such as hydrogen and an oxygen-containing gas such as air into the fuel cell 33 from the outside, and the fuel cell 33 is heated to a predetermined temperature to generate power. The used fuel gas and oxygen-containing gas are combusted and the combustion gas is discharged out of the storage container.

In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention. For example, the inner electrode may be formed from an oxygen side electrode. Further, a reaction preventing layer may be formed between the oxygen side electrode 33d and the solid electrolyte 33c. Further, the support substrate 33a and the fuel side electrode 33b may be formed with the same composition. For example, ZrO _{2 in} which Ni and Y ₂ O ₃ are dissolved may be used. That is, the support substrate 33a may also serve as the fuel side electrode 33b.

  Of course, various methods may be used for forming the oxygen side electrode 33d and the current collecting film 33g.

First, NiO powder having an average particle size of 0.5 μm and Y ₂ O ₃ powder having an average particle size of 0.9 μm were calcined and reduced, so that the volume ratio was 48% by volume for Ni and 52% by volume for Y ₂ O _3. Then, a clay prepared with an organic binder and a solvent was molded by extrusion molding, dried and degreased to prepare a support substrate molded body.

Next, a slurry prepared by mixing a Ni 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 is prepared, and applied to the support substrate molded body by a screen printing method. It dried and the coating layer for fuel side electrodes was formed.

Next, a slurry obtained by mixing ZrO _{2 in} which the amount of scandium in the amount shown in Table 1 was dissolved and ZrO ₂ powder in which 8 mol% of Y ₂ O ₃ was dissolved as a comparative example, with an organic binder and a solvent, respectively. The solid electrolyte layer sheets were respectively prepared by a doctor blade method, attached to the coating layer for the fuel side electrode on the support substrate molded body, and dried. That is, the solid electrolyte layer sheet and the fuel-side electrode coating layer were extended from one side main surface of the support substrate molded body to the other side main surface via the side surface.

  Next, the laminated molded body obtained by laminating the support substrate molded body, the fuel electrode coating layer, and the solid electrolyte molded body was calcined at 1000 ° C.

Next, an element diffusion prevention layer slurry prepared by adding and mixing an acrylic binder and toluene to a composite oxide containing 85 mol% CeO ₂ and 15 mol% Sm ₂ O ₃ (hereinafter referred to as SDC15) is obtained. It was applied to the surface of the solid electrolyte molded body of the calcined body by a screen printing method.

Further, a slurry in which a LaCrO ₃ oxide, an organic binder and a solvent are mixed is prepared, and this is laminated on the other main surface of the exposed support substrate molded body, and co-fired at 1485 ° C. in an oxygen-containing atmosphere. did.

Next, La _0.6 Sr _0.4 Co _0.8 Fe _0.2 O ₃ powder having an average particle diameter of 0.8 μm and SDC 15 prepared to a degree of aggregation of 13 to 16 are mixed, and the obtained slurry is laminated. The surface of the body element diffusion prevention layer is printed and dried at 130 ° C. to produce an oxygen-side electrode molded body, and the La _0.6 Sr _0.4 Co _0.8 Fe _0.2 O ₃ is prepared. A slurry obtained by mixing powder and isopropyl alcohol is printed and applied onto an interconnector to form a current collector film, and baked at 1050 ° C. to form an oxygen electrode layer and a current collector film. A fuel battery cell as shown in FIG.

  The size of the produced fuel cell is 25 mm × 200 mm, the thickness of the support substrate is 2 to 5 mm, the open porosity is 35%, the thickness of the fuel side electrode is 10 μm, the open porosity is 24%, and the oxygen side electrode The thickness was 50 μm, the open porosity was 40%, the thickness of the solid electrolyte layer was 10 to 50 μm, the relative density was 97%, and the thickness of the element diffusion preventing layer was 5 μm.

  Next, hydrogen gas was allowed to flow inside the fuel cell, and the support substrate and the fuel side electrode were subjected to reduction treatment at 850 ° C.

  A fuel gas was circulated through the fuel gas passage of the obtained fuel cell, an oxygen-containing gas was circulated outside the cell, and the fuel cell was heated to 750 ° C. using an electric furnace, and a power generation test was performed. The power generation characteristics at this time were confirmed.

Moreover, using the solid electrolyte raw materials described in Table 1, powders obtained by adding 2.5% PVA as solids to these raw materials were produced, and the size was 6 mm × 46 mm × 5 mm with a pressing pressure of 1000 kgf / cm ^2. A molded body was prepared. The molded body was fired at 1485 ° C. for 2 hours in the air. Using the obtained test piece, the electric conductivity in the atmosphere at 750 ° C. was measured by a four-terminal method. Furthermore, the strength of the solid electrolyte material was evaluated by 4-point bending (JIS-R1601). Furthermore, the residual stress generated on the solid electrolyte surface of the cell after co-firing and the residual stress generated on the solid electrolyte surface of the cell reduced at 850 ° C. for 16 hours with a mixed gas of 4% hydrogen and 96% nitrogen X Residual stress was calculated by calculating from the peak shift of zirconia in line diffraction, and the amount of change before and after the reduction treatment was determined. These results are shown in Table 1.

From this table, it was found that in the sample of the present invention, the power generation characteristics are greatly improved by decreasing the electric resistance of the solid electrolyte. In the sample of the present invention containing Sc ₂ O ₃ , sample No. 8 using 8YSZ as the solid electrolyte material was used. It was found that the strength was higher than 9 and the electric conductivity at 750 ° C. was large, and the residual stress generated in the solid electrolyte during reduction was small and stable.

It is a cross-sectional perspective view which shows the fuel battery cell of this invention. It is a cross-sectional view showing a cell stack of the present invention. It is a cross-sectional view showing a conventional fuel cell.

Explanation of symbols

33 ... Fuel cell 33a ... Conductive support 33b ... Fuel side electrode (inner electrode)
33c: Solid electrolyte 33d: Oxygen side electrode (outer electrode)
33f ... interconnector 34 ... gas flow path

Claims (7)

A fuel cell comprising a porous support substrate having a gas flow path and at least a dense solid electrolyte and a porous outer electrode sequentially provided on one main surface and a dense interconnector on the other main surface, The solid electrolyte formed on one side main surface of the support substrate is extended to the interconnector end surface formed on the other side main surface of the support substrate through the side surface of the support substrate, and the solid electrolyte is A fuel cell comprising a zirconium oxide in which scandium is dissolved. The fuel cell according to claim 1, wherein a thickness between main surfaces of the support substrate is 2 to 5 μm. The fuel cell according to claim 1, wherein the side surface of the support substrate has a curved surface that protrudes outward. 4. The fuel cell according to claim 3, wherein the side surface of the support substrate is a curved surface having a curvature radius of 1 to 3 [mu] m. 2. A fuel-side electrode, a solid electrolyte, and an oxygen-side electrode are sequentially formed on one main surface of a support substrate mainly composed of a rare earth element oxide and Ni and / or NiO. The fuel battery cell according to any one of 4. A fuel cell comprising a plurality of the fuel cells according to claim 1 in a storage container. The fuel cell according to claim 6, wherein the fuel cell is used for distributed power generation.

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