JP4544874B2 - Fuel cell and fuel cell - Google Patents

Description

  The present invention relates to a fuel cell having a dense interconnector in contact with an oxygen-containing gas and a hydrogen-containing gas, and a fuel cell.

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

Figure 3 is a conventional shows a cell stack of a solid electrolyte fuel cell, the cell stack is aligned set a plurality of fuel cells 1, a fuel while the adjacent battery cells 1a and the other fuel cell 1b A current collecting member 5 made of metal felt is interposed between the fuel electrode 7 of one fuel cell 1a and an oxygen electrode (air electrode) 11 of the other fuel cell 1b. It had been.

  In the fuel cell 1 (1a, 1b), a solid electrolyte 9 and an oxygen electrode 11 made of conductive ceramics are sequentially provided on the outer peripheral surface of a fuel electrode 7 made of a cylindrical cermet (the inside becomes a fuel gas passage). An interconnector 13 is provided on the surface of the fuel electrode 7 that is configured and is not covered with the solid electrolyte 9 or the oxygen electrode 11. As apparent from FIG. 3, the interconnector 13 is electrically connected to the fuel electrode 7 so as not to be connected to the oxygen electrode 11.

  The interconnector 13 is formed of conductive ceramics that are not easily altered by oxygen-containing gas such as fuel gas and air. The conductive ceramics are disposed between the fuel gas flowing inside the fuel electrode 7 and the outside of the oxygen electrode 11. It must be dense to ensure that it shuts off the flowing oxygen-containing gas.

  The current collecting member 5 provided between the adjacent fuel cells 1a, 1b is electrically connected to the fuel electrode 7 of one fuel cell 1a via the interconnector 13, and the other fuel cell. It is connected to the oxygen electrode 11 of the cell 1b, so that adjacent fuel cells are connected in series.

  The fuel cell is configured by accommodating a cell stack having the above structure in a storage container, and a fuel gas (hydrogen) is allowed to flow inside the fuel electrode 7 and an air (oxygen) is allowed to flow to the oxygen electrode 11 at about 1000 ° C. It generates electricity.

In the fuel cell constituting the fuel cell described above, generally, the fuel electrode 7 is formed of Ni and ZrO ₂ (YSZ) containing Y ₂ O ₃ , and the solid electrolyte 9 contains Y ₂ O ₃ . It is formed from ZrO 2 _(YSZ) for the oxygen electrode 11 is composed of a perovskite-type composite oxide of lanthanum manganate system. In addition, the interconnector 13 is generally composed of lanthanum chromite-based porcelain, and in order to adjust the difference in thermal expansion coefficient from YSZ constituting the solid electrolyte 9, LaCrO ₃ is made of Ti, Mg, Fe, Co, Ni, Zn, or the like. At least one element is dissolved in the solid, and oxides of these thermal expansion adjusting elements are present (see, for example, Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 11-3720 JP 2001-342056 A

  However, when the interconnector as described above can be used to adjust the difference in thermal expansion from the solid electrolyte, the oxide of the thermal expansion adjusting element such as Mg and Ti in the interconnector desorbs and adsorbs hydrogen at the power generation temperature. It was newly discovered that there is a nature. For this reason, there is a problem that the hydrogen flowing inside the fuel electrode cannot be completely separated by the interconnector and the fuel utilization rate is low.

  It is an object of the present invention to provide a fuel cell and a fuel cell that can reliably separate an oxygen-containing gas and a hydrogen-containing gas with an interconnector.

The fuel cell of the present invention includes a power generation unit in which a porous inner electrode, a dense solid electrolyte, and a porous outer electrode are provided in this order on a porous support, and the power generation unit is provided. A fuel cell comprising a dense interconnector that is in contact with an oxygen-containing gas and a hydrogen-containing gas at a portion that is not provided, wherein the interconnector is disposed on the support side, and a LaCrO ₃ oxide. A thermal expansion adjustment layer containing at least one oxide of Mg, Al, Ti, Fe, Co, Sr and Ca, and a LaCrO ₃ -based oxide disposed on the surface of the thermal expansion adjustment layer And a hydrogen non-adsorbing layer that does not contain Mg, Al, Ti, Fe, Co, Sr, and Ca oxides. In such a fuel cell interconnector is to have Mg, Al, Ti, Fe, Co, a non-hydrogen adsorption layer containing no oxide of Sr and C a, even during power generation, elimination adsorb hydrogen The non-adsorbing hydrogen layer can completely separate the hydrogen with the interconnector and improve the fuel utilization rate. Moreover, the strength of the fuel cell can be maintained by providing the support separately from the inner electrode.

Further, the fuel cell of the present invention forms a circular body, the said hydrogen-containing gas and the oxygen-containing gas supplied to the inside and outside of the annular member is blocked by said interconnector and the solid electrolyte Tei Rukoto is desirable, furthermore, the inner electrode, the fuel-side electrode der Rukoto exposed to the hydrogen-containing gas inside said annular body is desirable. In such fuel cells, depending on the solid electrolyte and the interconnect data, it is possible to separate a hydrogen-containing gas and oxygen-containing gas as the fuel gas.

The solid electrolyte is preferably a stabilized zirconia or lanthanum gallate-based porcelain. Moreover, it is desirable that the fuel cell has a hollow flat plate shape .

  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, since the fuel utilization rate of the fuel cell can be improved, the fuel utilization rate can also be improved as a fuel cell.

In the fuel battery cell of the present invention, the interconnector includes a LaCrO ₃ oxide disposed on the support side and at least one oxide of Mg, Al, Ti, Fe, Co, Sr, and Ca. a thermal expansion control layer containing, disposed on the surface of the thermal expansion adjustment layer contains a LaCrO ₃ type oxide, containing Mg, Al, Ti, Fe, Co, oxides of Sr and C a Since the hydrogen non-adsorbing layer is not present, hydrogen can be completely separated by the interconnector even during power generation, and the fuel utilization rate can be improved. Moreover, the strength of the fuel cell can be maintained by providing the support separately from the inner electrode.

In FIG. 1 showing a cross section of the fuel battery cell of the present invention, the fuel battery cell indicated by 30 as a whole has a flat cross section, and is an elongated substrate-like conductive support (hereinafter referred to as a support). It may be omitted.) 31 is provided. Inside the support 31, it is formed through a plurality of fuel gas passages 31a have a length direction at appropriate intervals, the fuel cell 30, various members are provided on the support 31 It has a structure. A plurality of such fuel cells 30 are connected to each other in series by a current collecting member 40 as shown in FIG. 2, thereby forming a cell stack constituting the fuel cell.

Support 31, as will be understood from the shape shown in FIG. 1, consists arcuate portion B of the two ends of the flat portion A and the flat portion A. Both surfaces of the flat portion A are formed substantially parallel to each other, and a fuel side electrode 32 is provided so as to cover one surface of the flat portion A and the arc-shaped portions B on both sides. to cover, and a solid electrolyte 3 3 dense stacked, the solid on the electrolyte 3 3, so as to face the fuel side electrode 32, oxygen electrode 34 on one surface of the flat portion a Are stacked.

Further, the other surface of the flat portion A of the fuel-side electrode 32 and the solid conductive Kaishitsu 3 3 is not laminated, the interconnector 35 is formed. As apparent from FIG. 1, the fuel-side electrode 32 and the solid electrolyte 3 3 extends to both sides of the interconnector 35, the surface of the support 31 is configured so as not to be exposed to the outside.

In the fuel cell having the above structure, the portion facing the oxygen electrode 34 of the fuel side electrode 32 operates as a fuel electrode to generate electric power. That is, the outer side of the oxygen electrode 34 by flowing oxygen-containing gas such as air, flowing fuel gas (hydrogen) in the gas passage 31a in either One in the support 31 is heated to a predetermined operating temperature, in the oxygen electrode 34 Electricity is generated by generating an electrode reaction of the following formula (1) and generating an electrode reaction of the following formula (2), for example, at the portion of the fuel side electrode 32 that becomes the fuel electrode.

Oxygen electrode: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte) (1)
Fuel electrode: O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻ (2)
Current generated by such generator is the collector through the interconnector 35 that is mounted on a support 31.

(Support)
In the fuel cell 30 having the above structure, the support 31, conducting the fuel gas that is gas permeable in order to transmit to the fuel electrode, and in order to perform current collection through the interconnector 35 In order to satisfy such requirements, it is required that the solid-state electrolyte is not cracked or peeled off due to the difference in thermal expansion during co-firing, and rare earth metals such as Y ₂ O _{3 and the} like. constituting the support 31 from the element oxide.

Iron group metal component is intended to impart conductivity to the support 31, may be an iron group metal simple substance, there also iron group metal oxide, an alloy or alloy oxide of iron group metal May be. The iron group metals include iron, nickel, and cobalt. In the present invention, any of them can be used, but Ni and / or NiO is changed to iron group because it is inexpensive and stable in fuel gas. It is preferable to contain as a component.

The rare earth oxides, the thermal expansion coefficient of the support 31, and is used to approximate the solid electrolyte 3 3 formed to have stabilized zirconia and lanthanum gallate-based perovskite compositions and the like. In particular the thermal expansion coefficient of the support member 31 in that to approximate a solid electrolyte material such as stabilized zirconia, iron group component described above, in the support 31 in an amount of 35 to 65 vol%, the rare earth element oxide things, it is preferable that in an amount of 35 to 65% by volume in the support 31. In particular, the rare earth element oxide of the support 31 is preferably Y ₂ O ₃ .

Note that in the support 31, the extent of long as required characteristics are not impaired may contain other metal components and oxide components.

Support 31 as described above, since it is necessary to have a fuel gas permeability, typically, open porosity of 30% or more, it is preferable in particular in the range 35 to 50%. The electric conductivity of the support 31, 300S / cm or more, and particularly preferably 440S / cm or more.

The length of the flat portion A of the support 31 is typically, 15 to 35 mm, the length of the arc-shaped portion B (length of the arc) is about 3 to 8 mm, the thickness of the support 31 (flat portion The distance between both surfaces of A) is preferably about 2.5 to 5 mm.

(Fuel side electrode)
In the present invention, the fuel side electrode 32 causes the electrode reaction of the above-described formula (2), and is formed from a known porous conductive ceramic. For example, it is formed from ZrO ₂ in which a rare earth element is dissolved, and Ni and / or NiO. As ZrO ₂ (stabilized zirconia) in which the rare earth element is dissolved, the same one used for forming the solid electrolyte 33 described below is preferably used.

  The stabilized zirconia content in the fuel side electrode 32 is preferably in the range of 35 to 65% by volume, and the Ni or NiO content is preferably 65 to 35% by volume. Further, the open porosity of the fuel side electrode 32 is preferably 15% or more, particularly in the range of 20 to 40%, and the thickness is desirably 1 to 30 μm.

Further, in the example of FIG. 1, the fuel side electrode 32 extends to both sides of the interconnector 35, but it is sufficient that the fuel electrode is formed at a position facing the oxygen electrode 34. For example, the fuel side electrode 32 may be formed only in the flat portion A on the side where the oxygen electrode 34 is provided. Further, it is also possible to form a fuel-side electrode 32 over the entire circumference of the support 31. In the present invention, in order to increase the bonding strength between the solid electrolyte 3 3 and the support 31, it is preferable that the whole of the solid electrolyte 3 3 are formed on the fuel side electrode 32.

(Solid electrolyte )
The solid electrolyte 3 3 provided on the fuel-side electrode 32 is generally 3 to 15 mol% of ZrO 2 _(usually stabilized zirconia) a rare earth element in solid solution is formed from a dense ceramic called Yes. Examples of rare earth elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, but high ion conductivity. Y, Yb, and Sc are desirable in that they have In the case where the solid electrolyte 33 is formed of ZrO ₂ in which Y is dissolved , the fuel cell 30 of the present invention includes an interconnector 35 having a LaCrO ₃ oxide, Mg, Al, Ti, Fe, Since it has a thermal expansion adjusting layer containing at least one oxide of Co, Sr, and Ca, the thermal expansion coefficient on the joining side of the interconnector 35 can be made closer to the solid electrolyte 33, and the fuel cell during power generation The damage of the cell 30 can be further suppressed.

The stabilized zirconia ceramic forming the solid electrolyte 33 is desirably a dense material having a relative density (according to Archimedes method) of 93% or more, particularly 95% or more from the viewpoint of preventing gas permeation. The thickness is desirably 10 to 100 μm. The solid electrolyte 3 3, in addition to stabilized zirconia, may be composed of lanthanum gallate-based perovskite composition.

(Oxygen electrode)
The oxygen electrode 34 is formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. As such a perovskite oxide, at least one of transition metal perovskite oxides, particularly LaMnO ₃ oxides, LaFeO ₃ oxides, and LaCoO ₃ oxides having La at the A site is preferable. LaFeO ₃ -based oxides are particularly suitable because they have high electrical conductivity at an operating temperature of about 1000 ° C. In the perovskite oxide, Sr and the like may exist together with La at the A site, and Co and Mn may exist together with Fe at the B site.

  The oxygen electrode 34 must have gas permeability. Therefore, the conductive ceramic (perovskite oxide) forming the oxygen electrode 34 has an open porosity of 20% or more, particularly 30 to 50. It is desirable to be in the range of%.

  The thickness of the oxygen electrode 34 is preferably 30 to 100 μm from the viewpoint of current collection.

(Interconnector)
In a position facing the above oxygen electrode 34, interconnector 35 provided on the support member 31 is made of a conductive ceramic, for contact with a fuel gas (hydrogen) and oxygen-containing gas, reduction resistance, It is necessary to have oxidation resistance. For this reason, lanthanum chromite perovskite oxide (LaCrO ₃ ) is generally used as the conductive ceramic. In order to prevent leakage of the oxygen-containing gas through the external fuel gas and the support 31 through the interior of support 31, such conductive ceramic must be dense, for example, 93% or more, particularly 95% It is preferable to have the above relative density.

  Furthermore, in the present invention, the interconnector 35 includes a thermal expansion adjustment layer 35a formed on the side bonded to the support, and a hydrogen non-contained element that does not contain a hydrogen adsorption element oxide formed on the surface of the thermal expansion adjustment layer 35a. It is comprised from the adsorption layer 35b.

Support or the like of the fuel cell is controlled to be close to the thermal expansion coefficient of the solid electrolyte, at least one of the past, _{LaCrO 3, Mg, Al, Ti} , Fe, Co, Sr and Ca is dissolved the thermal expansion adjustment element, and Mg in the grain boundary of _{LaCrO 3, Al, Ti, Fe} , Co, has been conducted to the presence of oxide of at least one of Sr and Ca, The thermal expansion adjusting layer 35a of the present invention has a similar configuration.

On the other hand, the oxides of Mg, Al, Ti, Fe, Co, Sr, and Ca can adjust the thermal expansion coefficient, but also have the property of adsorbing hydrogen. It has a hydrogen non-adsorbing layer 35b that does not contain (thermal expansion adjusting element oxide).

  The thickness of the thermal expansion adjusting layer 35a is preferably thin, but is preferably thicker than the hydrogen non-adsorbing layer 35b. As described above, since the hydrogen non-adsorption layer 35b does not contain a thermal expansion adjustment element oxide, the thermal expansion coefficient difference from the solid electrolyte is large, but the thickness of the thermal expansion adjustment layer 35a is larger than that of the hydrogen non-adsorption layer 35b. By increasing the thickness, peeling of the interconnector can be suppressed. The thickness of the hydrogen non-adsorbing layer 35b is desirably 10 to 50 μm. By setting it as this thickness, a fuel gas utilization factor can be improved and peeling of an interconnector etc. can be suppressed.

  The interconnector 35 is desirably 10 to 200 μm from the viewpoint of preventing gas leakage and electrical resistance.

Further, as it is apparent from FIG. 1, in order to prevent leakage of gas, on both sides of the interconnector 35, the solid electrolyte 3 3 dense in close contact, in order to enhance the sealing property, for example, It can be provided bonding layer composed of Ni and / or Ni and YSZ (not shown) between the sides and the solid electrolyte 3 3 of the interconnector 35.

  A P-type semiconductor layer 39 is preferably provided on the outer surface (upper surface) of the hydrogen non-adsorbing layer 35b. That is, in the cell stack (see FIG. 2) assembled from this fuel cell, the conductive current collecting member 40 is connected to the interconnector. However, when the current collecting member 40 is directly connected to the interconnector, non-connection Due to the ohmic contact, the potential drop increases, and the current collecting performance decreases.

However, by connecting the current collecting member 40 to the hydrogen non-adsorbing layer 35b via the P-type semiconductor layer 39, the contact between the two becomes an ohmic contact, the potential drop is reduced, and the deterioration of the current collecting performance is effectively avoided. it becomes possible to, for example, a current from the oxygen electrode 34 of one fuel cell 30 can be efficiently transmitted to the support member 31 of the other fuel cell 30. As such a P-type semiconductor, a transition metal perovskite oxide can be exemplified.

Specifically, those having higher electronic conductivity than LaCrO ₃ oxides constituting the interconnector 35 , for example, LaMnO ₃ oxides and LaFeO ₃ oxides in which Mn, Fe, Co, etc. exist at the B site P-type semiconductor ceramics made of at least one of LaCoO ₃ -based oxides can be used. In general, the thickness of the P-type semiconductor layer 39 is preferably in the range of 30 to 100 μm.

Further, the interconnector 35 is solid electrolyte 3 3 may be provided directly on the flat portion A of the support 31 on the side not provided, the fuel-side electrode 32 is provided in this section, the fuel-side electrode An interconnector 35 can also be provided on 32. That is, the fuel-side electrode 32 provided over the entire circumference of the support 31 can be provided with the interconnector 35 on the fuel side electrode 32. That is, the case in which the interconnector on the support 31 through the fuel-side electrode 32 is advantageous in that it is possible to suppress the potential drop at the interface between the support 31 and the interconnector 35 .

(Manufacture of fuel cells)
The fuel battery cell having the above structure is manufactured as follows.

First, an iron group metal or its oxide powder such as Ni, and Y ₂ O ₃ powder, an organic binder and a solvent were mixed to prepare a slurry, a press-molded by using this slurry, the support shaping Make a body and dry it.

Next, a fuel-side electrode forming material (Ni or NiO powder and stabilized zirconia powder), an organic binder and a solvent are mixed to prepare a slurry, and a sheet for the fuel-side electrode is prepared using this slurry. Further, instead of preparing a sheet for the fuel side electrode, a paste in which a fuel electrode forming material is dispersed in a solvent is applied to a predetermined position of the formed support body and dried, and then the fuel side electrode is formed. A coating layer may be formed.

Furthermore, a stabilized zirconia powder, an organic binder, a slurry is prepared by mixing a solvent, to prepare a sheet for solid electrolyte with the slurry.

Support molded body formed as described above, the sheet for fuel side electrodes sheet and solid electrolyte, are stacked so that the layer structure as shown in FIG. 1, for example, be dried. In this case, when the coating layer for fuel-side electrode is formed on the surface of the support compacts, only sheet for the solid electrolyte laminated to a support shaped body may be dried.

Thereafter, a sheet-like molded body of the interconnector is produced. First, Mg, Al, Ti, Fe, Co, prepared commercial LaCrO ₃ powder least one is solid-solved among Sr and Ca, which in an organic binder and a solvent were mixed to prepare a slurry, hydrogen to prepare a non-adsorbed layer sheet, while the commercial LaCrO ₃ powder the Mg and the like in a solid solution, Mg, Al, Ti, Fe, Co, at least one oxide powder of Sr and Ca, an organic binder And the solvent was mixed and slurry was prepared, the thermal expansion adjustment layer sheet was produced, the hydrogen non-adsorption layer sheet and the thermal expansion adjustment layer sheet were laminated | stacked, and the sheet-like molded object of the interconnector was produced.

The commercially available LaCrO ₃ powder forming the hydrogen non-adsorbing layer sheet may contain Fe, Ca, etc. as unavoidable impurities, but these unavoidable impurities are dissolved in LaCrO ₃ during firing, and LaCrO _{3 It} does not exist at the grain boundary ₃ . On the other hand, an oxide such as Mg added to the LaCrO ₃ powder partially dissolves in LaCrO ₃ , but most of it exists as an oxide at the grain boundary.

  The interconnector sheet is laminated so that the thermal expansion adjusting layer sheet is in contact with a predetermined position of the laminated body to produce a fired laminated body.

Next, the above-mentioned fired laminate is subjected to binder removal treatment, and co-fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere, and an oxygen electrode forming material (for example, LaFeO ₃₎ is placed at a predetermined position of the obtained sintered body. And paste containing a P-type semiconductor layer forming material (for example, LaFeO ₃ -based oxide powder) and a solvent by dipping or the like, if necessary. The fuel cell 30 of the present invention having the structure shown in FIG. 1 can be manufactured by baking.

Incidentally, in the case of using Ni alone in the formation of the support 31 and the fuel-side electrode 32, by firing in an oxygen-containing atmosphere, but Ni has become oxidized NiO, if necessary, by reduction treatment , Ni can be returned.

(Cell stack)
As shown in FIG. 2, the cell stack includes a plurality of the fuel cells 30 described above, and a metal felt and / or between one fuel cell 30 and the other fuel cell 30 adjacent in the vertical direction. A current collecting member 40 made of a metal plate is interposed, and both are connected in series with each other. That is, the support member 31 of one fuel cell 30 has a thermal expansion control layer 35a, the hydrogen non-adsorbed layer 35b, P-type semiconductor layer 39, via the collector member 40, the oxygen electrode 34 of the other fuel cell 30 Is electrically connected. Such cell stacks are arranged side by side as shown in FIG. 2, and adjacent cell stacks are connected in series by a conductive member 42.

  The fuel cell of the present invention is configured by accommodating the cell stack of FIG. 2 in a storage container. The storage container is provided with an introduction pipe for introducing a fuel gas such as hydrogen into the fuel cell 30 from the outside, and an introduction pipe for introducing an oxygen-containing gas such as air into the external space of the fuel battery cell 30. The fuel cell is heated to a predetermined temperature (for example, 600 to 900 ° C.) to generate electric power, and 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, it is also possible to the shape of the support cylindrical, between the oxygen electrode and the solid electrolyte, it is possible to form an intermediate layer having a suitable conductivity. Further, an oxygen electrode may be formed inside the solid electrolyte.

First, NiO powder having an average particle size of 0.5 μm and Y ₂ O ₃ powder (average particle size is 0.6 to 0.9 μm), NiO after firing is 48% by volume in terms of Ni, and Y ₂ O ₃ is were mixed so as to become 52% by volume, the cup soil prepared with an organic binder and a solvent subjected to molding at an extrusion forming shape method, which drying was degreased and to prepare a support green body.

Then produce an average particle size 0.5 [mu] m Ni powder and slurry for ZrO ₂ powder and an organic binder and a fuel side electrodes of the solvent mixture of a rare earth element in solid solution in, the support body formed body, a screen printing method And dried to obtain a laminate.

Next, a slurry obtained by mixing ZrO ₂ powder in which 10 mol% of scandia is dissolved, an organic binder, and a solvent is used to prepare a 40 μm sheet by the doctor blade method, and is adhered to the support molded body with an adhesion liquid. Apply and dry. After drying, a laminate was produced.

Next, supporting bearing member molded body, and the fuel-side electrode formed body, solid electrolyte molded body molded laminate obtained by laminating a was calcined at 1000 ° C.. On the solid electrolyte side of the obtained calcined body, a slurry prepared by mixing a composite oxide containing Ce and Sm and an organic binder as a diffusion preventing layer is baked to a thickness of 10 μm by screen printing. And then dried.

Then the surface opposite to the solid electrolyte green body and the current collecting and purpose of gas separation, were laminated sheet materials of the interconnector. Interconnector molded article, Mg, Al, Ti, Fe , Co, Sr Oyo by at least one of the beauty Ca (referred to as M), commercially available substituted by y amount shown in Table ₁ La _(M y Cr 1 _-y) prepare _0.96 O ₃ powder, to which to prepare a slurry by mixing an acrylic binder and a solvent, to prepare a non-hydrogen adsorption layer sheet by a doctor blade method, Mg, Al, Ti, Fe, Co, (referred to as M) of at least one of Sr and Ca is a commercially available _{La (M 0.3 Cr 0.7) 0.96} O 3 powder was replaced by 0.3 mole, the powder 100 Mg, Al, Ti, Fe, Co, at least one oxide powder of Sr and Ca was added by 10 parts by mass per part by mass, to prepare a slurry by mixing an acrylic binder and a solvent, Dr. Bray The thermal expansion control layer sheet was produced in the law, by laminating a non-hydrogen adsorption layer sheet and the thermal expansion control layer sheet, to prepare a sheet-shaped molded bodies of the interconnector.

  The interconnector sheet-like molded body was laminated so that the thermal expansion adjusting layer sheet was in contact with a predetermined position of the laminated body, and then dried and co-fired at 1470 ° C. in an oxygen-containing atmosphere.

Next, a mixed liquid composed of La _0.6 Sr _0.4 Co _0.6 Fe _0.4 O ₃ powder having an average particle diameter of 0.7 μm and isopropyl alcohol was prepared, and the surface of the solid electrolyte of the laminate was formed. spray applied to form an acid Motokyoku moldings, baked at 1050 ° C. to form an acid Motokyoku to prepare a fuel cell.

In the dimensions of the fuel cell is 25 mm × 150 mm were prepared, Thickness of the conductive support is 3 mm, Thickness is 10μm fuel side electrode, Thickness acid Motokyoku is 50 [mu] m, the area was 25 cm ² .

  Next, hydrogen gas was allowed to flow inside the fuel cell, and the conductive support and the fuel electrode were reduced at 850 ° C.

The fuel gas was circulated through the fuel gas flow path of the obtained fuel cell, the oxygen-containing gas was circulated outside the cell, the fuel cell was heated to 750 ° C. using a tubular furnace, and 0.44 A / cm ^2. The fuel utilization rate at the time of power generation at the current density was calculated by measuring the voltage while reducing the fuel supply amount, and obtaining the gas amount immediately before the sudden voltage drop occurred. The thermal expansion adjustment _{layer, MgO, Fe 2 O 3,} CoO, CaO, SrO, was added 10 parts by weight _Al 2 O 3, TiO.

  From Table 1, a sample No. of a comparative example having only a thermal expansion adjusting layer was obtained. In samples 6, 8, 10, 12, 14, 16, 18, and 20, the fuel utilization rate was 72% or less, and sample Nos. Of comparative examples in which no hydrogen non-adsorbing layer was formed. In No. 21, the interconnector peeled off during firing due to a mismatch in thermal expansion.

  In contrast, in the sample of the present invention having the thermal expansion adjusting layer and the hydrogen non-adsorbing layer, it is possible to prevent hydrogen leakage because the hydrogen that has diffused and moved in the thermal expansion adjusting layer is blocked by the hydrogen non-adsorbing layer. As a result, a fuel utilization rate of 90% or more can be achieved.

The fuel cell of this invention is shown, (a) is a cross-sectional view, (b) is a cross-sectional perspective view. It is a cross-sectional view showing a cell stack formed by a plurality of fuel cells. It is a cross-sectional view which shows the cell stack which consists of the conventional fuel cell.

Explanation of symbols

31 ... conductive support 31a ... fuel gas passages 32 fuel-side electrode 33 ... solid electrolyte 34 ... oxygen electrode 35 ... interconnector 35a ... thermal expansion adjustment layer 35b ... Hydrogen non-adsorption layer

Claims (6)

Provided with a power generation unit in which a porous inner electrode, a dense solid electrolyte, and a porous outer electrode are provided in this order on a porous support, and an oxygen-containing gas at a site where the power generation unit is not provided A fuel cell comprising a dense interconnector in contact with the hydrogen-containing gas,
The interconnector is disposed on the support side, and includes a LaCrO ₃ oxide and a thermal expansion adjustment layer containing at least one oxide of Mg, Al, Ti, Fe, Co, Sr, and Ca. A hydrogen non-adsorbing layer that contains a LaCrO ₃ -based oxide and that does not contain Mg, Al, Ti, Fe, Co, Sr, and Ca oxides, disposed on the surface of the thermal expansion adjustment layer; A fuel battery cell comprising:   2. The annular body is formed by the solid electrolyte and the interconnector, and the oxygen-containing gas and the hydrogen-containing gas supplied to the inside and outside of the annular body are blocked. The fuel cell described.   The fuel cell according to claim 1 or 2, wherein the inner electrode is a fuel side electrode exposed to the hydrogen-containing gas.   The fuel cell according to any one of claims 1 to 3, wherein the solid electrolyte is stabilized zirconia or lanthanum gallate porcelain.   The fuel battery cell according to any one of claims 1 to 4, wherein the fuel battery cell has a hollow flat plate shape.   A fuel cell comprising a plurality of the fuel cells according to claim 1 in a storage container.

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