JP4544872B2 - Fuel cell and fuel cell - Google Patents

Description

The present invention relates to a fuel cell及beauty fuel cells.

  In recent years, various fuel cells in which a stack of fuel cells is stored in a storage container have been proposed as next-generation energy.

Figure 3 shows a cell stack of a conventional solid electrolyte fuel cell, the cell stack is aligned set a plurality of fuel cells 1, one of the fuel cell 1 and the other fuel cell 1 and the A current collecting member 3 made of metal felt is interposed therebetween, and the fuel side electrode 1a of one fuel cell 1 and the oxygen side electrode 1b of the other fuel cell 1 are electrically connected.

  The fuel cell 1 is configured by sequentially providing a porous fuel-side electrode 1a, a dense solid electrolyte 1d, and an oxygen-side electrode 1b made of porous conductive ceramics on the outer peripheral surface of the support 1c. The support 1c exposed from the solid electrolyte 1d and the oxygen side electrode 1b is provided with an interconnector 1e so as not to be connected to the oxygen side electrode 1b, and is electrically connected to the fuel side electrode 1a.

  The interconnector 1e is a dense material that reliably shuts off the fuel gas flowing inside the fuel side electrode 1a and the oxygen-containing gas flowing outside the oxygen-side electrode 1b, and is hardly changed by the fuel gas and the oxygen-containing gas. New conductive ceramics are used.

  The electrical connection between one fuel cell 1 and the other fuel cell 1 is performed by connecting the fuel-side electrode 1a of one fuel cell 1 via an interconnector 1e provided on a support 1c and a current collecting member 3. This is done by connecting to the oxygen side electrode 1b of the other fuel cell 1.

  The fuel cell is configured by storing the cell stack in a storage container, supplying fuel gas (hydrogen) into the support 1c, supplying oxygen-containing gas to the oxygen side electrode 1b, and generating electric power at about 1000 ° C. The

In such a fuel cell 1, in general, the support 1c, the fuel side electrode 1a are made of Ni and ZrO ₂ (YSZ) containing Y ₂ O ₃ , and the solid electrolyte 1d is made of Y ₂ O ₃ . The oxygen side electrode 1b is made of a transition metal perovskite oxide and is made of ZrO ₂ (YSZ).

  Further, as a method of manufacturing the fuel cell 1 as described above, in recent years, in order to simplify the manufacturing process and reduce the manufacturing cost, the support 1c, the fuel side electrode 1a, the solid electrolyte 1d, the interconnector A so-called co-sintering method in which 1e is simultaneously fired has been proposed. This co-sintering method is a very simple process and has a small number of manufacturing steps, and is advantageous in improving the yield during manufacturing of cells and reducing costs.

However, in the conventional fuel cell 1, the support 1 c is composed of Ni and ZrO ₂ containing Y ₂ O ₃ , and the thermal expansion coefficient of Ni is 16.3 × 10 ⁻⁶ / ° C. Since the thermal expansion coefficient of ZrO ₂ containing Y ₂ O ₃ is 10.8 × 10 ⁻⁶ / ° C., the thermal expansion coefficient of the support 1 c is added to the solid electrolyte 1 d made of ZrO ₂ containing Y ₂ O _3. When the support 1c and the solid electrolyte 1d are simultaneously fired in order to simplify the cell manufacturing process, cracks are generated in the solid electrolyte 1d, or the solid electrolyte 1d is formed on the support 1c. There was a problem of peeling from the fuel side electrode 1a.

Therefore, in recent years, in order to approximate the thermal expansion coefficient of the solid electrolyte and the support, a support, Ni and a low thermal expansion coefficient than the ZrO ₂ mullite _{(3Al 2 O 3 · 2SiO 2} ) and spinel (MgAl ₂ O ₄ and CaAl ₂ O ₄ ) are formed (see Patent Document 1).
JP-A-7-029574

  However, in such a fuel battery cell 1, even if the support 1c and the solid electrolyte 1d are co-fired, the thermal expansion coefficient of the support 1c can be brought close to the thermal expansion coefficient of the solid electrolyte 1d. Although cracking of the solid electrolyte 1d and separation of the solid electrolyte 1d from the fuel-side electrode 1a can be suppressed, components such as Mg, Al, and Si of the support 1c diffuse into the solid electrolyte 1d during simultaneous firing, and ion conduction of the solid electrolyte 1d There is a problem that the power generation performance of the fuel cell 1 is lowered.

Therefore, the applicant of the present invention is the iron group metal and / or iron group metal oxide as the support 1c, and one kind selected from Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr. and it suggested as a main component oxides of the above rare earth elements (Japanese Patent Application No. 2002-024980).

  According to this fuel cell, the power generation performance can be improved. However, as a result of detailed analysis of the fuel cell to further improve the output, the output between the oxygen side electrode and the fuel side electrode is improved when co-sintered. However, it was found that the potential drop between the fuel electrode and the interconnector was slightly larger than before.

The reason why this potential drop is slightly larger than before is not clear. However, as a result of analyzing the cross section of the interface between the support and the interconnector by EPMA, for example, when the support contains Y ₂ O ₃ , the interconnector The diffusion of the La component contained in and the diffusion of the Y component contained in the support were observed, and segregation of both was observed at this interface. From this, it is presumed that an insulating reaction layer made of La—Y—O system is formed at the interface between the two, and the potential drop is increased.

The present invention comprises a conductive support and a potential drop between the interconnector can be reduced, and to provide a high power generation capacity fuel cell及beauty fuel cells.

Fuel cell of the present invention, on the electrically conductive substrate, the fuel-side electrode, the solid electrolyte, the oxygen side electrodes are sequentially provided, at a portion where the fuel side electrode on the conductive support is not provided, the conductive a fuel cell comprising an interconnector is provided via sexual intermediate layer, wherein the conductive support is made of a Ni and / or NiO and ceramic particles, wherein the conductive intermediate layer is Ni and / or NiO And ZrO ₂ or CeO _{2 formed} by dissolving a rare earth element as a solid solution.

In such a fuel cell, typically an interconnector made of a ceramic, between the Ni and / or the conductive support ing from the NiO and ceramic particles, and Ni and / or NiO, solid rare earth elements Since a conductive intermediate film made of dissolved ZrO ₂ or CeO ₂ is formed, the intermediate film between the interconnector and the conductive support allows mutual diffusion of elements between the two during simultaneous firing The potential drop between the conductive support and the interconnector can be reduced, and the bonding strength between the interconnector and the conductive support can be improved. Furthermore, since the conductive intermediate film contains Ni and / or NiO, the conductivity between the interconnector and the conductive support can be improved.

Further, the fuel cell of the present invention, the abundance ratio of ZrO ₂ or CeO ₂ formed by a solid solution of a rare earth element of the conductive intermediate layer is that less than the presence ratio of the ceramic particles before Kishirube conductive support It is characterized by.

In such a fuel cell, a rare earth element is fixed between the interconnector and the conductive support provided with the interconnector at an abundance ratio smaller than the abundance ratio of the ceramic particles of the conductive support body. since the conductive intermediate layer containing ZrO ₂ or CeO ₂ formed by soluble are formed, the more than Ni of Ni amount Gashirube conductive support in the conductive intermediate layer, the interconnector and the conductive The conductivity between the conductive support can be improved.

Furthermore, the fuel cell of the present invention, the conductive support, together comprising an oxide of a rare earth element as the ceramic particles, the interconnector lanthanum - made of a chromium-containing oxide material, wherein the conductive The support, the fuel side electrode, the solid electrolyte, the conductive intermediate film, and the interconnector are simultaneously sintered.

In such a fuel cell, between the electrically conductive substrate and the interconnector, by providing a Ni and / or NiO, a conductive intermediate layer containing a ZrO ₂ solid solution of rare earth ing In addition, it is possible to suppress the mutual diffusion of La and rare earth elements between the two at the time of simultaneous firing, to reduce the potential drop between the conductive support and the interconnector, and to provide a fuel cell with high power generation capability.

In such a fuel cell, the conductive support is composed of a composition containing a rare earth element oxide and Ni and / or NiO, thereby eliminating the adverse effect of the conductive support on the solid electrolyte. Therefore, the ionic conductivity of the solid electrolyte can be increased, and a fuel cell excellent in power generation performance can be provided.

In such a fuel cell, the rare earth element oxide hardly dissolves or reacts with the iron group metal and / or iron group metal oxide during firing or during power generation, and the conductive support is used as a conductive support. Oxides of rare earth elements to be mixed, for example, Y ₂ O ₃ has a thermal expansion coefficient of 8.14 × 10 ⁻⁶ / ° C., Yb ₂ O ₃ is almost the same as Y ₂ O ₃ , and the rare earth elements are dissolved. Since it is much smaller than the thermal expansion coefficient of ZrO ₂ (about 10.8 × 10 ⁻⁶ / ° C.), by controlling the content ratio of Y ₂ O ₃ , Yb ₂ O _3, etc. The expansion coefficient can be made close to the thermal expansion coefficient of the solid electrolyte. Further, by using a rare earth element oxide having a small thermal expansion coefficient, the amount of Ni in the conductive support can be increased, the electrical conductivity of the conductive support can be improved, and the fuel cell Cell characteristics can be improved.

In addition, since the conductive support mainly contains Ni and / or NiO and a specific rare earth element oxide, the rare earth element diffuses into the solid electrolyte even if the conductive support and the solid electrolyte are simultaneously fired. The solid electrolyte does not adversely affect the ionic conductivity of the solid electrolyte, the conductivity of the oxygen side electrode, and the like, and even if the rare earth element diffuses during simultaneous firing, the solid electrolyte is originally Y ₂ O ₃ , Yb ₂ O _3. Since it is composed of ZrO ₂ in which an oxide of a rare earth element such as a solid is dissolved, the influence on the solid electrolyte can be suppressed to a minimum. Moreover, oxides of rare earth elements such as Y ₂ O ₃ and Yb ₂ O ₃ are used as solid electrolyte stabilizers and can prevent an increase in the number of element types in the fuel cell.

Furthermore, in the fuel cell according to the present invention, the oxide of the rare earth element in the conductive support is one or more selected from Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr. wherein the of an oxide of a rare earth element. In such a fuel cell, an oxide of a rare earth element of the conductive support, the support is an oxide of a small rare earth thermal expansion coefficient, to increase the iron group metal content of the conductive support in Therefore, the electrical conductivity of the conductive support can be increased, and the power generation capacity of the fuel cell can be improved.

Further, the fuel cell of the present invention is characterized in that the thickness of the conductive intermediate layer is 20μm or less. In such a fuel cell, the conductive intermediate layer, tends to trace while La component is diffused, the conductive intermediate layer can reduce the resistance by thin as 20μm or less, thereby conducting Potential drop through the conductive interlayer can be reduced. Furthermore, by reducing the thickness of the conductive intermediate film, even if the thermal expansion coefficient of the conductive intermediate film is different from that of the interconnector, the fuel-side electrode, or the conductive support, it is possible to prevent peeling of the conductive intermediate film. .

Furthermore, the fuel cell of the present invention is characterized in that a collector layer made of P-type semiconductor on the interconnector surface. If current is collected directly on the surface of the interconnector via a metal current collecting member, 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 a P-type semiconductor to the interconnector. For example, it is important to use a perovskite oxide that is a P-type semiconductor. Accordingly, the potential drop at the interface between the interconnector and the current collector can be made smaller than when the current is collected directly on the surface of the interconnector via the metal current collector.

Further, the fuel cell of the present invention, before Kishirubeden intermediate film rare earth element is dissolved in ZrO ₂ or CeO ₂ of, Y, Lu, Yb, Tm , Er, Ho, Dy, Gd, Sm, Pr ZrO ₂ or CeO ₂ containing at least one element selected from the group consisting of

In such a fuel cell, it is possible to suppress mutual diffusion of La and rare earth elements between the two at the time of simultaneous firing, and the conductive intermediate film is formed from ZrO ₂ or CeO ₂ which are ceramic particles having electronic conductivity. The potential drop between the conductive support and the interconnector can be reduced, and a fuel cell with high power generation capability can be provided.

Furthermore, the fuel cell of the present invention, the conductive ZrO ₂ or CeO ₂ formed by a solid solution of a rare earth element of the intermediate layer is 35 to 45 vol%, the ceramic particles before Kishirube conductive support 35 to 65 volume %. In such a fuel cell, since the conductive intermediate film containing few ceramic particles is formed, the conductivity between the interconnector and the conductive support can be improved.

The fuel cell according to the present invention is characterized in that a plurality of the fuel cells are accommodated in a storage container. In such a fuel cell, the fuel cell can be prevented from being damaged due to the difference in thermal expansion between the conductive support and the solid electrolyte, and the potential drop at the interface between the conductive support and the interconnector can be suppressed. An excellent fuel cell can be provided.

In the fuel cell of the present invention, generally the interconnector consists of ceramic, between the Ni and / or the conductive support ing from the NiO and ceramic particles, and Ni and / or NiO, solid rare earth elements Since a conductive intermediate film made of dissolved ZrO ₂ or CeO ₂ is formed, the conductive intermediate film between the interconnector and the conductive support allows the elements between the two to be simultaneously fired. Mutual diffusion can be suppressed , the potential drop between the conductive support and the interconnector can be reduced, and the bonding strength between the interconnector and the conductive support can be improved. Furthermore, since the conductive intermediate film contains Ni , the conductivity between the interconnector and the conductive support can be improved.

  FIG. 1 is a cross-sectional perspective view of a fuel battery cell 33 according to the present invention. The fuel battery cell 33 has a flat cross-section and is generally a flat bar shape (hollow flat plate type). A plurality of gas flow paths 34 are formed in the axial length direction.

The fuel cell 33 has a flat cross section, and one or more kinds selected from Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr which are long and flat as a whole. conductive support 33a containing an oxide and Ni and / or NiO of rare earth elements on the outer surface (hereinafter, if there is. abbreviated as support), a porous fuel side electrode 33b, dense solid electrolyte 33c The oxygen side electrode 33d made of porous conductive ceramics is sequentially laminated, and a conductive intermediate film 33e (hereinafter sometimes abbreviated as an intermediate film) is formed on the outer surface of the support 33a opposite to the oxygen side electrode 33d. An interconnector 33f made of a lanthanum-chromium oxide material and a current collecting film 33g made of a P-type semiconductor material are formed.

That is, the fuel cell 33 has a cross-sectional shape including arc-shaped portions m provided at both ends in the width direction, and a pair of flat portions n that connect the arc-shaped portions m. It is flat and formed substantially in parallel. One of the pair of flat portions n of these fuel cell 33, the flat portion of the support member 33 a, an intermediate layer 33e, the interconnector 33f, configured to form a current-collecting film 33 g, the other flat portion n Is configured by forming a fuel side electrode 33b, a solid electrolyte 33c, and an oxygen side electrode 33d on a flat portion of the support 33a.

Conductive intermediate layer 33e is that Do since N i and / or NiO and a rare earth element and ZrO ₂ or CeO ₂ ing a solid solution.

Examples of the rare earth elements, Y, Lu, Yb, Tm , Er, Ho, Dy, Gd, Sm, at least one elemental selected from the group consisting of Pr is suitably used.

The Ni conversion amount of the Ni compound in the intermediate film 33e is desirably 35 to 80% by volume, preferably 50 to 70% by volume, and more desirably 55 to 65% by volume in terms of improving the conductivity. In other words, ZrO ₂ or CeO ₂ formed by dissolving the rare earth element in the intermediate film 33e is 20 to 65% by volume, preferably 30 to 50% by volume, and more preferably 35 to 45% by volume. By setting the Ni conversion amount in the intermediate film 33e to 35% by volume or more, the Ni conductive path is increased, the conductivity of the intermediate film 33e is improved, and the voltage drop is reduced. Moreover, by making Ni 80 volume% or less, the thermal expansion coefficient difference between the support body 33a and the interconnector 33f can be made small, and generation | occurrence | production of the crack in both interface can be suppressed.

  In addition, the thickness of the intermediate film 33e is preferably 20 μm or less, and more preferably 10 μm or less from the viewpoint that the potential drop is reduced. In addition, by reducing the thickness of the intermediate film 33e in this way, even if the thermal expansion coefficient difference between the interconnector 33f and the support 33a and the intermediate film 33e is large, interfacial cracks between them are suppressed. it can. 6 μm or more is desirable from the viewpoint of preventing diffusion.

The rare earth element of the support 33a is preferably a medium rare earth element or a heavy rare earth element. The thermal expansion coefficient of the medium rare earth element or heavy rare earth element oxide is smaller than that of ZrO ₂ containing Y ₂ O ₃ of the solid electrolyte 33c, and the support 33a as a cermet material with Ni is used. Can be made closer 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. With the oxide thermal expansion coefficient smaller heavy rare earth element, can increase the Ni in the support 33a, from the viewpoint that it is possible to increase the electrical conductivity of the support 33a, furthermore, oxides of heavy rare earth elements It is desirable to use

Incidentally, La of the light rare earth elements, Ce, Pr, oxides of Nd, if the summed area of the thermal expansion coefficient of the oxide is less than the thermal expansion coefficient of the solid electrolyte of the rare earth elements, middle rare earth elements, heavy rare earth There is no problem even if it is contained in addition to the elements.

In addition, the raw material cost can be significantly reduced by using an oxide of a complex rare earth element including a plurality of inexpensive rare earth elements in the course of purification. Also in that case, it is important that the thermal expansion coefficient of the oxide of the complex rare earth element is less than the thermal expansion coefficient of the solid electrolyte.

Such electroconductive support 33a is an oxide of a rare earth element as the ceramic particles, it is desirable to contain N i and / or NiO, oxides of rare earth elements, Y, Lu, Yb, Tm, Er , Ho, Dy, Gd, Sm , it is preferable that the oxide of one or more rare earth elements selected from Pr. The support 33a preferably contains 35 to 65% by volume of a rare earth element oxide and 35 to 65% by volume of Ni and / or NiO in terms of Ni. By setting it as such a composition ratio, while being able to ensure electroconductivity, it can approximate to the thermal expansion coefficient of a solid electrolyte.

In the present invention, it is desirable that the abundance ratio of ZrO ₂ or CeO _{2 formed} by dissolving the rare earth element in the conductive intermediate film 33e is smaller than the abundance ratio of the ceramic particles of the conductive support 33a. Conversely, the existence ratio of Ni in terms of Ni and / or NiO conductive intermediate layer 33e may be desirable more than the presence ratio of Ni in terms of the conductive support 33a.

  Further, the interconnector 33f is made of a lanthanum-chromium oxide material, and is usually formed by adding additives such as Mg and Sr for sintering at a low temperature. When such an additive is added, the coefficient of thermal expansion tends to be high. However, as described above, the interface between the support 33a and the interconnector 33f can be obtained by setting the thickness of the intermediate film 33e to 20 μm or less. Cracks can be suppressed.

  It is desirable to provide a current collecting film 33g made of a P-type semiconductor such as 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 desirable to connect a current collecting 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 lanthanum-manganese oxide, lanthanum-iron oxide, or a composite oxide thereof.

The fuel side electrode 33b provided on the outer surface of the support 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 fuel side electrode 33b is desirably joined to both ends of the intermediate film 33e.

The solid electrolyte 33c provided on the outer surface of the fuel side electrode 33b is composed of a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing, for example, 3 to 15 mol% of a rare earth element such as Y. . As the rare earth element, Y or Yb is desirable because it is inexpensive.

  The thickness of the solid electrolyte 33c is desirably 10 to 100 μm. Gas permeation can be prevented by setting the thickness of the solid electrolyte 33c to 10 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.

The oxygen side electrode 33d is composed of a lanthanum-manganese oxide, a lanthanum-iron oxide of a transition metal perovskite oxide, or at least one porous conductive ceramic of a composite oxide thereof. Yes. The oxygen side electrode 33d is preferably (La, Sr) (Fe, Co) O ₃ from the viewpoint 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.

  A part of the outer surface of the support 33a has a portion in which the fuel side electrode 33b, the solid electrolyte 33c, and the oxygen side electrode 33d are not formed in the axial length direction. The solid electrolyte 33c and the oxygen side electrode An intermediate film 33e, an interconnector 33f made of lanthanum-chromium oxide, and a current collecting film 33g are formed on the outer surface of the support 33a exposed from 33d.

  The interconnector 33f is made dense to prevent leakage of the fuel gas and oxygen-containing gas inside and outside the support 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. For example, a bonding layer made of Y ₂ O ₃ may be interposed between the end face of the interconnector 33f and the end face of the solid electrolyte 33c in order to improve the sealing performance.

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 the mixed powder is used with a support material in which an organic binder and a solvent are mixed. Extruded to produce a flat support molded body, which is dried and degreased.

Next, Ni and / or NiO powder, a ZrO ₂ powder in which a rare earth element is dissolved, an organic binder, and a solvent are mixed, and a sheet-like fuel-side electrode molded body is manufactured using the prepared slurry, and the support is molded. Laminate on the body.

Next, using a solid electrolyte material in which a rare earth element solid solution ZrO ₂ powder, an organic binder, and a solvent are mixed, a sheet-like solid electrolyte molded body is produced, and the fuel-side electrode molded body on the support molded body The sheet-like solid electrolyte molded body is laminated and wound on the substrate and dried. In addition, you may degrease at this time.

Next, a sheet-like intermediate film molded body is produced using a slurry in which Ni and / or NiO powder, a rare earth element-dissolved ZrO ₂ powder, an organic binder, and a solvent are mixed, and is laminated on the support body 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, and is laminated on the intermediate film molded body.

  As a result, the fuel-side electrode molded body and the solid electrolyte molded body are sequentially laminated on the surface of one flat portion of the support molded body, and the intermediate film molded body and the interconnector molded body are laminated on the surface of the other flat portion. A laminated molded body is produced. Each molded body can be produced by sheet molding using a doctor blade, printing, slurry dip, spraying by spraying, or the like, or 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 produced by forming an electrode molded body and a current collector film molded body by dipping, or by direct spray coating and baking at 1000 to 1300 ° C.

The fuel cell 33 is, by firing in an oxygen-containing atmosphere, since the conductive substrate 33a, the fuel-side electrode 33b, Ni component in the intermediate layer 33 e has a NiO, then the support 33a side Then, a reducing fuel gas is flowed to reduce NiO at 800 to 1000 ° C. Further, this reduction process may be performed during power generation.

  As shown in FIG. 2, the cell stack is composed of a plurality of fuel battery cells 33, and a metal felt and / or a metal plate is interposed between one fuel battery cell 33 and the other fuel battery cell 33. The support member 33a of one fuel battery cell 33 is inserted into the other fuel battery cell via the interconnector 33f, the current collector film 33g, and the current collector member 43 provided on the support member 33a. It is configured to be electrically connected to 33 oxygen side electrodes 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. Then, surplus fuel gas and oxygen-containing gas are burned and 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, a cylindrical fuel cell may be produced using a cylindrical support, and the shape is not limited as long as the fuel cell uses a support. Further, a reaction preventing layer may be formed between the oxygen side electrode 33d and the solid electrolyte 33c.

  Moreover, although the said form demonstrated the example which formed the fuel side electrode on the support body 33a, this invention may be the fuel cell of the fuel side electrode support which does not have a support body separately. In this case, the interconnector is formed on the fuel side electrode via the intermediate film.

  First, NiO powder having an average particle diameter of 0.5 μm and an oxide of Group 3a element (RE) in the periodic table shown in Table 1 having an average particle diameter of 0.8 to 1.0 μm after firing are converted into Ni. The mixing was performed so that the ratio was 50% by volume and the volume ratio of the RE oxide was 50% by volume.

  Next, a support material formed by mixing the mixed powder with an organic binder composed of a pore agent and PVA and a solvent composed of water is extruded to produce a flat support compact, It dried and heated up to 1000 degreeC, degreased and calcined, and produced the support body molded object.

Next, the amount of Ni converted after firing ZrO ₂ (YSZ) powder containing 8 mol% Y ₂ O ₃ and the above-described NiO powder is 50% by volume, and the volume ratio of YSZ is 50% by volume. In addition, a slurry to be a fuel side electrode 33b in which an organic binder made of acrylic resin and a solvent made of toluene are mixed is prepared, and the YSZ powder, an organic binder made of acrylic resin, and a solvent made of toluene A sheet-like molded body is prepared using a solid electrolyte material mixed with the catalyst, and a slurry to be the fuel-side electrode 33b is printed on the sheet-shaped molded body, and the support-molded body is spread so that the solid electrolyte molded body side is on the outside. Applied, laminated and dried.

Next, the content of the NiO powder having an average particle size of 0.5 μm and the ZrO ₂ powder containing 8 mol% of the rare earth elements shown in Table 1 having an average particle size of 0.8 μm, whose volume ratio after firing is shown in Table 1 It mixed so that it might become. NiO is a Ni conversion amount. This mixed powder, an organic binder made of an acrylic resin, and a solvent made of toluene were mixed to produce a sheet-like intermediate film molded body.

Thereafter, a sheet-like molded body was produced using an interconnector material obtained by mixing a La (MgCr) O ₃ -based material having an average particle diameter of 1.1 μm, an organic binder made of an acrylic resin, and a solvent made of toluene.

  The sheet-like intermediate film molded body is laminated on the interconnector sheet-shaped molded body, and further, the intermediate film molded body side is laminated on the outer surface of the flat portion of the exposed support molded body so that the support molded body side is supported. A laminated molded body in which a fuel-side electrode molded body, a solid electrolyte molded body, an intermediate film molded body, and an interconnector molded body were laminated on the body molded body was produced. Next, this laminated molded body was degreased and further fired at 1500 ° C. in the air.

Next, a mixed liquid composed of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ powder having an average particle diameter of 2 μm and isopropyl alcohol is prepared, and the surface of the solid electrolyte 33c of the multilayer molded body, Further, each of the surfaces of the interconnector 33f is spray-applied to form an oxygen side electrode molded body and a current collector film molded body and baked at 1150 ° C. to form an oxygen side electrode 33d and a current collector film 33g. Was made.

  Next, hydrogen gas was flowed from the support 33a side of the fuel battery cell 33, and reduction treatment was performed at 850 ° C.

  The support 33a had a width of 26 mm, a thickness of 3.5 mm and a length of 200 mm, and the oxygen side electrode 33d had a width of 24 mm and a length of 130 mm. The thickness of the fuel side electrode 33b was 10 μm, the thickness of the solid electrolyte 33c was 30 μm, the thickness of the oxygen side electrode 33d was 50 μm, the thickness of the interconnector 33f was 50 μm, and the thickness of the current collecting film 33g was 50 μm. The thickness of the intermediate film 33e is shown in Table 1.

  The thicknesses of the fuel side electrode 33b, the solid electrolyte 33c, the oxygen side electrode 33d, the intermediate film 33e, the interconnector 33f, and the current collecting film 33g were obtained from SEM observation of the cross section.

A Pt current collecting member is formed on the oxygen side electrode 33d and the current collecting film 33g of the fuel battery cell 33 thus produced, and a voltage line is attached to the current collecting member, and at the same time, a Pt line is connected to the gas flow path 34. The fuel cell 33 is heated to 850 ° C., the oxygen-containing gas is supplied to the oxygen-side electrode 33d, the fuel gas is supplied to the fuel-side electrode 33b, the power is generated, and the current is taken out. The potential drop between the reference electrode and the current collector at a current density of 4 A / cm ² was measured. The measured values are shown in Table 1.

From Table 1, it can be seen from Sample No. 1 that is outside the scope of the present invention in which the intermediate film 33e is not formed between the support 33a and the interconnector 33f. No. 1 had a large potential drop of 110 mV at a current density of 0.4 A / cm ² . On the other hand, between the support 33a and the interconnector 33f, it can be seen that reducing the potential drop by the formation of intermediate layer 33e Do that because the ZrO ₂ comprising a solid solution of Ni and rare earth elements.

That is, the sample No. of the present invention. 3 to 11 and 13 to 26, by forming an intermediate film 33e made of ZrO ₂ cermet containing Ni and rare earth elements between the support 33a and the interconnector 33f, a current density of 0.4 A / cm ² is obtained. The potential drop at that time could be reduced to 53 mV or less, and the output of the fuel cell 33 could be increased.

Further, the sample No. 5 in which the Ni conversion amount of the Ni compound in the intermediate film 33e is 35 to 80% by volume. Nos. 4 to 11 can further reduce the potential drop at a current density of 0.4 A / cm ² to 33 mV or less. 5 to 8, the potential drop at a current density of 0.4 A / cm ² can be reduced to 27 mV or less. In 6 and 7, the potential drop could be reduced to 21 mV or less.

Sample No. 5 was obtained by changing the Ni conversion amount of the Ni compound contained in the intermediate film 33e to 65% by volume and changing the thickness of the intermediate film 33e in the range of 5 to 30 μm. As for Samples 13 to 16, the sample No. 16 shows that the potential drop is a little as large as 53 mV. Therefore, it can be seen that the thickness of the intermediate film 33e is preferably 20 μm or less, particularly preferably 10 μm or less.

In addition, the sample No. 1 in which the rare earth element in the support 33a is fixed to Y and the rare earth element in the intermediate film 33e is changed. 17-No. 21, sample No. 1 in which the rare earth elements in the support 33a and the intermediate film 33e were changed. 22-No. In each case, the potential drop at a current density of 0.4 A / cm ² was as small as 37 mV or less.

On the other hand, the sample No. 1 having an intermediate film 33e of Ni alone not containing ZrO _{2 in} which the rare earth element was dissolved in the comparative example. In No. ² , cracks were observed between the intermediate film 33e, the support 33a, and the interconnector 33f, and the potential drop at a current density of 0.4 A / cm ² was as large as 123 mV. The potential drop gradually increases when the Ni conversion amount is 70 to 85% by volume. This is because the thermal expansion coefficient of the intermediate film 33e increases and the thermal expansion with the interconnector increases as the Ni amount increases. It is thought that micro cracks have occurred due to the coefficient difference.

Further, sample No. 1 having an intermediate film 33e made of ZrO ₂ alone in which a rare earth element not containing Ni is dissolved is used as a comparative example. 12 has a very large potential drop of 244 mV at a current density of 0.4 A / cm ² because the resistance of the intermediate layer 33 e increases.

Based on Example 1, NiO powder having an average particle diameter of 0.5 μm and CeO ₂ powder containing 20 mol% of the rare earth elements shown in Table 2 having an average particle diameter of 0.8 μm, the volume ratio after firing is shown in Table 2. A fuel cell was produced and evaluated in the same manner as in Example 1 using the intermediate film material mixed so as to have the content shown.

Further, using a support substrate material in which NiO powder having an average particle size of 0.5 μm and Y ₂ O ₃ having an average particle size of 0.8 to 1.0 μm are mixed so that the volume ratio after firing is as shown in Table 2. In the same manner as in Example 1, a fuel cell was produced and evaluated. These results are shown in Table 2.

The Table 2, between the support 33a and the interconnector 33f, it can be seen that reducing the potential drop by forming an intermediate layer 33e made of CeO ₂ Metropolitan comprising a solid solution of Ni and rare earth elements.

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 cell stack.

Explanation of symbols

33 ... Fuel cell 33a ... Conductive support 33b ... Fuel side electrode 33c ... Solid electrolyte 33d ... Oxygen side electrode 33e ... Conductive intermediate film 33f ... Interconnector 33g ... Current collector film

Claims (9)

On a conductive support, fuel-side electrode, the solid electrolyte, the oxygen side electrodes are sequentially provided, at a portion where the fuel side electrode on the conductive support is not provided, the interconnector via the conductive intermediate layer a fuel cell is provided, wherein the conductive support is made of a Ni and / or NiO and ceramic particles, wherein the conductive intermediate layer is a solid solution with Ni and / or NiO, a rare earth element A fuel cell comprising: ZrO ₂ or CeO ₂ . Existence ratio of ZrO ₂ or CeO ₂ formed by a solid solution of a rare earth element of the conductive intermediate layer is, prior to Kishirube conductive support of the proportions according to claim 1, wherein the less than the ceramic particles Fuel cell. Wherein the conductive support is a conjunction comprising an oxide of a rare earth element as the ceramic particles, the interconnector lanthanum - made of a chromium-containing oxide material, wherein the conductive support, wherein the fuel-side electrode, the solid 3. The fuel cell according to claim 1, wherein the electrolyte, the conductive intermediate film, and the interconnector are simultaneously sintered. Oxides of rare earth elements in the conductive support is a Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, oxides of one or more rare earth elements selected from Pr The fuel cell according to claim 3.   The fuel cell according to any one of claims 1 to 4, wherein the thickness of the conductive intermediate film is 20 µm or less.   6. The fuel cell according to claim 1, wherein a current collecting film made of a P-type semiconductor is provided on the surface of the interconnector. The rare earth element dissolved in ZrO ₂ or CeO ₂ of the conductive intermediate film is at least one selected from the group consisting of Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr. The fuel battery cell according to claim 1, wherein the fuel battery cell is provided. Claims, characterized in that the ZrO ₂ or CeO ₂ formed by a solid solution of a rare earth element of the conductive intermediate layer is 35 to 45 vol%, the ceramic particles before Kishirube conductive support is 35 to 65 vol% Item 8. The fuel cell according to any one of Items 1 to 7.   A fuel cell comprising a plurality of the fuel cells according to any one of claims 1 to 8 in a storage container.

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