JP4130796B2 - SOFC fuel electrode containing ceria-based perovskite oxide and method for producing the same - Google Patents

Description

  The present invention relates to a fuel electrode for SOFC containing a ceria-based perovskite oxide and a method for producing the same.

  In recent years, there has been an increasing interest in fuel cells (SOFCs) using oxides, which are oxygen ion conductors, as electrolytes. However, these fuel cells are not subject to Carnot efficiency and have essentially high energy conversion efficiency. It has excellent features such as better environmental protection.

For the purpose of improving the power generation characteristics, improvement of the ionic conductivity of the electrolyte and reduction in the thickness of the electrolyte are being studied. As the solid electrolyte, rare earth-doped zirconia ((1-x) ZrO ₂ -xA ₂ O ₃ , A is an element such as Y, Sc, 0.03 ≦ x ≦ 0.12, and a small amount of alumina or the like is added to this. In some cases, it may be stabilized into cubic crystals), and its thinning is being studied.

Further, as an electrolyte excellent in ion conductivity particularly at a low temperature of 500 ° C. to 750 ° C., for example, Ce _0.8 Sm _0.2 O ₂ (SDC) which is a ceria-based electrolyte added with rare earths, or a lanthanum gallate-based electrolyte _{La 0.8 Sr 0.2 Ga 0.85 Mg 0.15} O 3 (LSGM) are also known, such as is.

The fuel cell has an air electrode and a fuel electrode sandwiched between electrolytes. These electrodes supply gas and electrons to the electrolyte and provide a place for an electrochemical reaction at the interface with the electrolyte. Yes. This reaction field is called a three-phase interface because the gas, electrons, and ions are in contact. The fuel electrode generally uses a mixture (cermet) of YSZ (0.92ZrO ₂ -0.08Y ₂ O ₃ ), which is an oxygen ion conductor, and a metal, such as Ni, which is an electron conductor. It occurs at the interface between Ni and YSZ. It is said that when a mixed conductor, which is a conductor for both electrons and oxygen ions, is in contact with this interface, the reaction field, that is, the three-phase interface, is remarkably expanded and the electrode characteristics are improved.

As examples of a mixed conductor that is stable in a reducing atmosphere, a ceria-based electrolyte material, La (Sr) Ga (Mg) O ₃ to which Co or Ni is added, and the like are known (Reference 1: Tatsuumi Ishihara and workers; Proc. Of Solid Oxide Fuel Cells-VI (1999) pp. 869-978 (Electrochemical Society Proceedings Volume 99-19)).

In particular, when a perovskite oxide such as La (Sr) Ga (Mg) O ₃ or La (Sr) VO ₃ , which is a complex oxide of rare earth and transition metal, is added to the fuel electrode, the valence of the transition metal is changed. Due to the high catalytic activity, carbon accumulation is unlikely to occur even when a hydrocarbon fuel is used (Reference 2: Shiqiang Hui, Anthony Pertric and Wenhe Gong; Proc. Of Solid Oxide Fuel Cells-VI (1999) pp. 632). -639 (Electrochemical Society Proceedings Volume 99-19)).

However, although the perovskite oxide has a structure having a trivalent cation having a large ionic radius such as La at the A site, the pyrochlore phase (La ₂ Zr ₂ O ₇ ) is easily formed. When this pyrochlore phase is generated, the electrode characteristics are remarkably deteriorated (Reference 3: Hiroshi Kawada, solid oxide fuel cell and global environment, p155-p175, Agne Jofu Co., Ltd.).

In addition, since a trivalent element such as La and a large ion radius easily reacts with carbon dioxide, there is a concern that when hydrocarbon is used as a fuel, an oxide containing La as a main component is partially decomposed to deteriorate electrode performance.
Tatsuumi Ishihara and cowers; Proc. of Solid Oxide Fuel Cells-VI (1999) pp. 869-978. (Electrochemical Society Proceedings Volume 99-19) Shiqiang Hui, Anthony Pertric and Wenhe Gong; Proc. of Solid Oxide Fuel Cells-VI (1999) pp. 632-639. (Electrochemical Society Proceedings Volume 99-19) By Hiroshi Kawada, Solid oxide fuel cell and global environment, p155-p175, Agne Jofusha)

  In the fuel electrode of a solid oxide fuel cell, the present invention is a conventional cermet composed of an electrolyte material and a metal such as Ni, and has a high catalytic activity of hydrocarbons. By preparing a fuel electrode by mixing mixed conductive oxides that do not cause a deterioration reaction in the above, generation of a pyrochlore phase leading to deterioration of the characteristics of the fuel electrode, carbon deposition, reaction deterioration with carbon dioxide gas, etc., and An object of the present invention is to provide a fuel electrode for SOFC containing a ceria-based perovskite oxide having high electrode performance possessed by a perovskite-based oxide, and a method for producing the same.

In order to solve the above problems, a fuel electrode for SOFC containing a ceria-based perovskite oxide according to the present invention is composed of a dense zirconia-based solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. In a fuel cell comprising a fuel cell and an interconnector for electrically connecting them, the fuel electrode comprises a cermet of an oxide and a metal, which is a mixture of a zirconia-based electrolyte material and a ceria-based perovskite oxide, The composition of the ceria-based perovskite oxide has the following formula (in CeM _x O ₃ , where M is one or more metal elements selected from Cr, V, Mn, Fe, and Co, and the total amount X is 0.6 < X < 1.5).

Furthermore, a fuel electrode for SOFC containing a ceria-based perovskite oxide according to the present invention is a fuel cell comprising a dense ceria-based solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and a In a fuel cell comprising an electrically connected interconnector, the fuel electrode is a cermet of a mixture of a ceria-based electrolyte material and a ceria-based perovskite oxide and a metal, and the ceria. The composition of the perovskite-type oxide is represented by the following formula (in CeM _x O ₃ , M is one or more metal elements selected from Cr, V, Mn, Fe, Co, and the total amount X is 0.6 < X < 1.5).

Further, a fuel electrode for SOFC containing a third ceria-based perovskite oxide according to the present invention is a fuel cell comprising a dense lanthanum gallate solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. In a fuel cell comprising a cell and an interconnector for electrically connecting them, the fuel electrode is a cermet of oxide and metal, which is a mixture of a zirconia-based electrolyte material and a ceria-based perovskite oxide, and the ceria The composition of the perovskite-type oxide is represented by the following formula (in CeM _x O ₃ , M is one or more metal elements selected from Cr, V, Mn, Fe, Co, and the total amount X is 0.6 < X < 1.5).

In the fuel electrode for SOFC containing the ceria-based perovskite oxide according to the present invention as described above, the CeM _x O ₃ is a part of M substituted with one or more elements selected from Al and Ga, In addition, a part of Ce can be substituted with one or more elements selected from Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y. At this time, the total substitution amount of atoms substituting Ce There 50% or less, and the total substitution amount of M is less than _{50% ([Ce 1-Z} Ln Z] [M 1-Y M1 Y] X; Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er , Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al; Ga; Z < 0.5; Y <0.5; 0.6 < X < 1.5). It is characterized by that.

In the CeM _x O ₃ , a part of M is replaced with one or more elements selected from Al and Ga, and a part of Ce is replaced with Ca, Sr, Nd, Sm, Gd, Eu, and Tb. , Dy, Ho, Er, Yb, Lu, Y can be substituted with one or more elements, wherein the total substitution amount of atoms substituting Ce is 50% or less and the total substitution amount for M is and 50% to 90%, and _{([Ce 1-Z Ln Z} ] [M 1-Y M1 Y] X; Ln = Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb , Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; 0.5 < Y < 0.9; 0.6 < X < 1.5) It is characterized by being.

Furthermore, a fuel electrode for SOFC containing a fourth ceria-based perovskite oxide according to the present invention is a fuel cell comprising a dense zirconia-based solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. And in a fuel cell comprising an interconnector that electrically connects them, the fuel electrode is composed of a cermet of an oxide and a metal, which is a mixture of a zirconia-based electrolyte material and a ceria-based perovskite oxide, and is a zirconia-based The ceria-based perovskite oxide covers the surface of the mixture of the electrolyte material and the metal as fine particles, and the content of the ceria-based perovskite oxide is 15 wt% or less in the fuel electrode, and the fuel electrode and After the firing of the electrolyte, the ceria-based perovskite oxide is added and the ceria-based perovskite is added. The composition of the type oxide in the formula _(CeM x _{O 3} M is Cr, V, Mn, Fe, at least one metal element selected from among Co, the total amount X is 0.1 <X <1. It is represented by 5).

A fuel electrode for SOFC containing a fifth ceria-based perovskite oxide according to the present invention is a fuel cell comprising a dense ceria-based solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and those In the fuel cell comprising an interconnector for electrically connecting the electrodes, the fuel electrode comprises a cermet of an oxide and a metal, which is a mixture of a ceria-based electrolyte material and a ceria-based perovskite oxide, and the ceria-based electrolyte material The ceria-based perovskite oxide covers the surface of the mixture of metal and metal as fine particles, the content of the ceria-based perovskite oxide is 15 wt% or less in the fuel electrode, and the fuel electrode and the electrolyte After the firing, ceria-based perovskite oxide is added, and the composition of the ceria-based perovskite oxide is _(CeM x M in _{O 3 Cr, V, Mn,} Fe, at least one metal element selected from among Co, the total amount X is 0.1 <X <1.5) to be represented by Features.

According to the sixth fuel electrode for SOFC containing a ceria-based perovskite oxide according to the present invention, a fuel cell comprising a dense lanthanum gallate solid electrolyte, a porous fuel electrode provided on both sides thereof, and an air electrode. In a fuel cell comprising a cell and an interconnector for electrically connecting them, the fuel electrode comprises a cermet of an oxide and a metal, which is a mixture of a ceria-based electrolyte material and a ceria-based perovskite oxide, and the ceria The ceria-based perovskite oxide covers the surface of the mixture of the electrolyte material and the metal as fine particles, the content of the ceria-based perovskite oxide is 15 wt% or less in the fuel electrode, and the fuel electrode And ceria-based perovskite oxide added after the firing of the electrolyte, and the ceria-based perovskite type The composition of the product is the following formula _(CeM x M in _{O 3 Cr, V, Mn,} Fe, at least one metal element selected from among Co, the total amount X is 0.1 <X <1.5) It is represented by.

In the fuel electrode for SOFC containing the fourth to sixth ceria-based perovskite oxides according to the present invention as described above, the CeM _x O ₃ is one or more selected from Al and Ga in a part of M. And a part of Ce is replaced with one or more elements selected from Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y. in total substitution amount less than 50%, and total substitution of the atoms for replacing Ce is less _{50% ([Ce 1-z} Ln z] [M 1-Y M1 Y] x; Ln = Sm, Eu, Gd , Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; Y <0.5; 0.1 < X < 1.5).

Furthermore, in the fuel electrode for SOFC containing the fourth to sixth ceria-based perovskite oxides according to the present invention as described above, the CeM _x O ₃ is a part of M selected from Al and Ga 1 Substituting with one or more elements, and replacing part of Ce with one or more elements selected from Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, and Y but this time the total amount of substitution M is and 90% or more 50% or less, and 50% or less total substitution of the atoms for replacing _{Ce ([Ce 1-z Ln} z] [M 1-Y M1 Y] _x ; Ln = Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0. 5; 0.5 <Y <0.9; and characterized in that it is 0.1 <X <1.5) That.

  The present invention provides the fourth fuel electrode manufacturing method, wherein a slurry of the zirconia-based electrolyte material and a metal is applied on the zirconia-based electrolyte, sintered, and then added with a solution of a ceria-based perovskite oxide. And firing.

  Further, the present invention provides the fifth fuel electrode manufacturing method, wherein a slurry of the ceria-based electrolyte material and the metal is applied on the ceria-based electrolyte and sintered, and then a ceria-based perovskite oxide solution. Is added and fired.

  Further, according to the third fuel electrode manufacturing method of the present invention, in the sixth fuel electrode manufacturing method, a slurry of the ceria-based electrolyte material and metal is applied and sintered on the lanthanum gallate-based electrolyte. After that, a solution of ceria-based perovskite oxide is added and fired.

  Further, in the fuel electrode manufacturing method described above, the ceria-based perovskite oxide solution is a sol-gel solution.

  By using an SOFC fuel electrode containing a ceria-based perovskite oxide as the fuel electrode of a solid oxide fuel cell, the pyrochlore phase that leads to the deterioration of the characteristics of the fuel electrode and the occurrence of carbon deposition and carbon dioxide destabilization do not occur. We succeeded in obtaining a cell with high electrode performance. The present invention greatly contributes to improving the efficiency of solid fuel cells.

  According to the present invention, a ceria-based perovskite oxide that can suppress carbon deposition and does not easily cause a deterioration reaction due to carbon dioxide gas is mixed with a cermet composed of a metal and an electrolyte material that are conventionally used in a fuel electrode. We use thing as fuel electrode. A mixture of La-based perovskite oxide in the fuel electrode is known, but a mixture of ceria-based perovskite oxide in the fuel electrode is not known. Ceria-based perovskite oxide itself lacks stability in an oxidizing atmosphere. In the present invention, the above-mentioned drawback is solved by using a conventional cermet for the skeleton of the fuel electrode.

  In the first invention of the present invention, the solid electrolyte is a zirconia-based solid electrolyte, and the fuel electrode is an oxide of a mixture of a zirconia-based electrolyte material and the ceria-based perovskite oxide described in detail above, a metal, Cermet.

  In the second invention according to the present invention, the solid electrolyte is a ceria-based solid electrolyte, and the fuel electrode is composed of an oxide, a metal, and a mixture of the ceria-based electrolyte material and the ceria-based perovskite oxide described in detail above. Cermet.

  According to a third aspect of the present invention, the solid electrolyte is a lanthanum gallate solid electrolyte, and the fuel electrode is composed of an oxide of a ceria-based electrolyte material and a mixture of the ceria-based perovskite oxide described in detail above, a metal, Cermet.

  According to a fourth aspect of the present invention, the solid electrolyte is a zirconia-based solid electrolyte, and the fuel electrode is composed of an oxide and a metal of a mixture of a zirconia-based electrolyte material and the ceria-based perovskite oxide described in detail above. It is a cermet, the surface of the mixture of the zirconia-based electrolyte material and the metal is covered with fine particles of ceria-based perovskite-type oxide, and the content of ceria-based perovskite-type oxide is 15 wt% or less at the fuel electrode. In addition, the ceria-based perovskite oxide is added after the firing of the fuel electrode and the electrolyte.

  According to a fifth aspect of the present invention, the solid electrolyte is a ceria-based solid electrolyte, and the fuel electrode is composed of an oxide and a metal of a mixture of a ceria-based electrolyte material and a ceria-based perovskite oxide described in detail above. It is a cermet, the surface of the mixture of the ceria-based electrolyte material and the metal is covered with fine particles of ceria-based perovskite-type oxide, and the content of ceria-based perovskite-type oxide is 15 wt% or less in the fuel electrode. In addition, the ceria-based perovskite oxide is added after the firing of the fuel electrode and the electrolyte.

  The sixth solid electrolyte according to the present invention is a lanthanum gallate-based solid electrolyte, and the fuel electrode is a cermet of an oxide and metal of a mixture of a zirconia-based electrolyte material and a ceria-based perovskite oxide described in detail above. The ceria-based perovskite oxide covers the surface of the mixture of the ceria-based electrolyte material and the metal as fine particles, and the content of the ceria-based perovskite-type oxide is 15 wt% or less in the fuel electrode; In addition, the ceria-based perovskite oxide is added after the firing of the fuel electrode and the electrolyte.

Here, the ceria-based perovskite oxide material is one or more metal elements selected from transition metals of Cr, V, Mn, Fe, and Co as the main element constituting M in CeM _x O _3. .

Here, the composition ratio of Ce and M is ideally 1: 1, but even a composition slightly deviated from here becomes a compound. That is, in the first to third inventions according to the present invention, 0.6 < x < 1.5. In the fourth to sixth inventions, 0.1 < x < 1.5 can be satisfied . In the fourth to sixth inventions added by impregnating the ceria-based perovskite oxide after firing, the composition of the metal M in CeM _x O ₃ is different from the first to third inventions of the present invention. The range is up to 0.1. This is because, since the firing temperature is low, the electrode characteristics are not greatly impaired even in this composition range. In the fourth to sixth inventions, preferably 0.3 < x < 1.2, and more preferably 0.8 < x < 1.0.

In the present invention, it is possible to replace the Ce and M with other elements, _i.e., can be _{[Ce 1-Z Ln Z]} [M 1-Y M1 Y] X O 3.

When a part of Ce is substituted with one or more elements selected from the trivalent cations Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, the main component is Ce. Therefore, the conductivity can be improved without substantially impairing the stability of the ceria system. In this case, Z < 0.5 from the examples described later. In this case, a part of the transition metal constituting M can be replaced with one or more of Al and Ga. The substitution amount of M is Y <0.5 as will be apparent from the examples described later.

Even if a small part of Ce is replaced with one or more elements selected from Ca, Sr, Nd, Sm, Gd, Eu, Tb, Dy, Ho, Er, Yb, Lu, and Y, it is almost the same. The following characteristics can be obtained. Also in this case, Z < 0.5 from the examples described later. Furthermore, a part of the transition metal constituting M can be replaced with one or more of Al and Ga. In this case, 0.5 < Y < 0.9, as will be apparent from the examples described later.

  In the fourth to sixth inventions according to the present invention, the surface of the mixture of the ceria-based electrolyte material and the metal is made ceria-based by adding the ceria-based perovskite oxide after the firing of the fuel electrode and the electrolyte. A structure in which the perovskite oxide is covered as fine particles can be obtained. In this case, the content of the ceria-based perovskite oxide needs to be 15 wt% or less when viewed from the whole fuel electrode. This is because the addition after the completion of firing fills the hole in the porous fuel electrode, and if the addition amount is less than this, the gas permeation performance is not significantly impaired. The content of the ceria-based perovskite oxide is preferably 0.05 to 15 wt%, particularly preferably 2 to 8 wt%.

  An example of the metal is Ni alloy.

Even if the ceria atoms constituting the ceria-based oxide diffuse to the zirconia side at the interface with zirconia, no pyrochlore phase is generated. Ce atoms of ceria-based oxides are tetravalent in an oxidizing atmosphere, but are reduced within the fuel electrode to an average valence of about 3.0 to 3.5. When mixed with transition metal in equimolarity, CeMO ₃ type Of the perovskite oxide. If transition metals such as Cr, V, Mn, Fe, and Co are used, these metals are exposed on the oxide surface, helping to oxidize hydrocarbons, thus suppressing carbon precipitation and reaction deterioration with carbon dioxide. Is done. For this reason, when a fuel electrode was produced using a material in which a ceria-based perovskite oxide and a conventional electrode material were mixed, no deterioration product such as a pyrochlore phase was produced with the zirconia electrolyte, and carbon deposition was suppressed. It becomes a high-performance fuel electrode.

  By the way, since these transition metals can take various valences, they have a high catalytic ability in the oxidation reaction of hydrocarbons, but some of these transition metals are replaced with Ga, Al, etc., which have a ionic radius and become trivalent cations. However, the same effect can be expected, and since the stability is improved, durability and the like can be expected. However, it is necessary to contain at least 10% of a transition metal.

  The present invention also provides a method for producing the fuel electrode according to the fourth to sixth inventions, and according to such a method, the fuel electrode base does not contain the ceria-based perovskite oxide on the electrolyte. A material is formed by firing, and the porous fuel electrode base material is impregnated with a ceria-based perovskite-type oxide solution dropwise, and then fired again to precipitate fine particles of the ceria-based perovskite-type oxide. Let As a result, the fine particles cover the fuel electrode substrate.

  In this case, when the fuel electrode of the fourth invention is manufactured, the fuel electrode base material is a mixture of a zirconia-based electrolyte material and a metal, and when the fuel electrode of the fifth and sixth inventions is manufactured, The fuel electrode substrate is the surface of a mixture of a ceria-based electrolyte material and a metal.

The solution is preferably a sol-gel solution of ceria-based perovskite oxide. Further, the ceria-based perovskite oxide may be obtained by substituting a part of M with one or more elements selected from Al and Ga in the CeM _x O ₃ and a part of Ce with Sm, Eu, Gd, Substitution with one or more elements selected from Tb, Dy, Ho, Er, Yb, Lu, and Y. At this time, the total substitution amount of M is less than 50%, and the total number of atoms substituting Ce substitution amount less _{50% ([Ce 1-z} Ln z] [M 1-Y M1 Y] x; Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr , V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; Y <0.5; 0.1 < X < 1.5).

Further, in the CeM _x O ₃ , a part of M is replaced with one or more elements selected from Al and Ga, and a part of Ce is replaced with Ca, Sr, Sm, Eu, Gd, Tb, Dy. , Ho, Er, Yb, Lu, Y are substituted with one or more elements. At this time, the total substitution amount of M is 50% or more and 90% or less, and the total number of atoms substituting Ce substitution amount less _{50% ([Ce 1-z} Ln z] [M 1-Y M1 Y] x; Ln = Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; 0.5 < Y < 0.9; 0.1 < X < 1.5). .

  Examples of the present invention will be described below. Of course, the present invention is not limited to the following examples.

First, a 0.2 mm-thick Sc ₂ O ₃ and Al ₂ O ₃ -added zirconia (SASZ or 0.895ZrO ₂ -0.10 Sc ₂ O ₃ -0.005Al ₂ O ₃ ) solid electrolyte substrate 1 fired by a doctor blade method A NiO—YSZ slurry (10 mol% Y ₂ O ₃ added zirconia YSZ 40 wt%, NiO 60 wt%) was applied on one side of this, and a platinum mesh current collector 4 was placed thereon and fired at 1200 ° C. for 2 hours. A fuel electrode 2 was provided. Next, a slurry of LSM (La _0.78 Sr _0.2 MnO ₃ ) was applied to the back surface, and fired under conditions of 1100 ° C. for 2 hours to form an air electrode 3. Both the fuel electrode 2 and the air electrode 3 have a diameter of 6 mm. This fuel cell is referred to as cell # 1-0. This is a comparative example.

Next, in the fuel electrode 2 in the comparative example, 50 wt% of YSZ is replaced with Ce _1.0 Fe _0.6 O ₃ , Ce _1.0 Fe _1.0 O ₃ , CeFe _1.5 O ₃ , Ce _{1.0. Mn 0.6 O 3, Ce 1.0 Mn} 1.0 O 3, CeMn 1.5 O 3, Ce 1.0 Co 0.6 O 3, Ce 1.0 Co 1.0 O 3, CeCo 1. Instead of a ceria-based perovskite oxide having a composition of ₅ O ₃ , Ce _1.0 Cr _1.0 O ₃ , Ce _1.0 V _1.0 O ₃ , a mixture of YSZ and ceria-based perovskite oxide is used. The fuel electrode used was produced. Let these be cells # 1-1 to # 1-11.

In addition, cell # 1-12 using an oxide having a composition of Ce _1.0 Co _0.1 Fe _0.5 Mn _0.2 Cr _0.1 V _0.1 O ₃ as a ceria-based perovskite oxide is manufactured. did. Further, when the substitution amount of YSZ with Ce _1.0 Fe _1.0 O ₃ is changed to 10 wt%, 20 wt%, and 80 wt%, cell # 1-2-1, cell # 1-2-2, cell # 1-2-3 was produced. And in the cell # 1-5, the metal used for the cermet is replaced with Ni, and a cell using Ni _0.5 Co _0.5 , Ni _0.5 Fe _0.5 , Ni _0.5 Mn _0.5 Cell # 1-5-1, Cell # 1-5-2, and Cell # 1-5-3 were produced.

A fuel cell shown in FIG. 1 was assembled using these cells and the cell of the comparative example, and a power generation test was performed at 800 ° C. Here, the fuel electrode gas mixture of steam and methane _{(H 2 O: CH 4 =} 0.5: mixing 1 molar ratio), the air electrode was supplied with oxygen. In the figure, 5 is a platinum terminal and 6 is a reference electrode (platinum).

As the open electromotive force, a value of 1.20 V or more was obtained. Table 1 shows the results of measurement of the overvoltage of the fuel electrode at 300 mA / cm ² in cells # 1-0 to # 1-12 together with cell # 1-0 as a comparative example. Here, the overvoltage of the fuel electrode was obtained by subtracting the ohmic resistance component from the potential difference from the platinum reference electrode 6 (in oxygen gas) provided on the electrolyte sheet by the current interrupt method. The cells # 1-1 to # 1-12 were able to have a lower overvoltage than the cell # 1-0 as a comparative example.

  Table 1 also shows each cell overvoltage after 500 hours from the start of operation. It can be seen that the increase in overvoltage is small and the stability over time is better than that of the cell of the comparative example. This is because the deposition of carbon was suppressed, and the deterioration of the fuel electrode overvoltage characteristics of the cell was small. As described above, the production method of the present invention succeeded in producing a fuel electrode having superior characteristics as compared with the conventional method.

＊セル＃１−１〜セル＃１−１２（セル＃１−２−１〜セル＃１−２−３を除く）におけるセリア系ペロブスカイト型酸化物の置換量は５０ｗｔ％である。
＊＊８００℃で測定。＊セル＃１−５−１〜セル＃１−５−３では、サーメットに使用する金属をＮｉに代えて、Ｎｉ_０．５Ｃｏ_０．５，Ｎｉ_０．５Ｆｅ_０．５，Ｎｉ_０．５Ｍｎ_０．５を用いている。 Table 1 Composition of fuel electrode and electrode active oxide and fuel electrode overvoltage in Example 1

* The replacement amount of the ceria-based perovskite oxide in cell # 1-1 to cell # 1-12 (excluding cell # 1-2-1 to cell # 1-2-3) is 50 wt%.
** Measured at 800 ° C. * In cell # 1-5-1 to cell # 1-5-3, Ni _0.5 Co _0.5 , Ni _0.5 Fe _0.5 , Ni _{0. 5} Mn _0.5 is used.

In the ceria-based oxide of Example 1 (CeMO ₃ , M = Fe, Co, Mn substituted by 50 wt%), a material obtained by substituting a part of Ce atoms with Sm at 10 at%, 20 at%, 50 at%, or Ce atoms Cells # 2-1 to # 2-8 were fabricated by firing the anode using a material partially substituted by Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, or Y at 20 at%. These cells were tested in the same manner as in Example 1. The results are shown in cells # 2-1 to # 2-8 in Table 2. Next, a cell having a fuel electrode in which a part of the transition metal M in the ceria-based oxide (CeMO ₃ ) was replaced with Al or Ga atoms by 10 at% and 50 at% was manufactured. Further, the composition is Ce _0.8 Sm _0.2 M _0.8 Al _0.2 O ₃ , Ce _0.8 Sm _0.2 M _0.8 Ga ₂ O ₃ , (M: Fe, Co, Mn) and Using ceria-based perovskite oxides of Ce _0.8 Y _0.2 Fe _0.8 Ga _0.2 O ₃ and Ce _0.8 Y _0.2 Fe _0.8 Al _0.2 O _{3 in} the same manner Produced. The test results of these fuel electrodes are shown in cells # 2-9 to # 2-24 in Table 2. All of them show better characteristics than Comparative Example Cell # 1-0.

＊セル＃２−１〜セル＃２−２４におけるセリア系ペロブスカイト型酸化物の置換量は５０ｗｔ％である。
＊８００℃で測定。 Table 2 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 2

* The substitution amount of the ceria-based perovskite oxide in cell # 2-1 to cell # 2-24 is 50 wt%.
* Measured at 800 ° C.

In Example 1, a portion of the Ce atom of the ceria-based oxide CeMO ₃ (M = Fe, Co, Mn) is substituted by 20 at% with Ca or Sr, and a part of the transition metal atom is 51 at% with Al or Ga. , 70 at%, 90 at% substituted materials were used to fire the fuel electrode to produce cells # 3-1 to # 3-12. Next, in the ceria-based oxide (CeMO ₃ ), a part of the Ce atom is substituted with Ca and Sm by 20 at%, or a part of the Ce atom is substituted with Ca and Y by 20 at%, or one of the Ce atoms is substituted. Cell # 3 in which part is replaced by 20 at% with Sr and Sm, or part of Ce atom is replaced with 20 at% with Sr and Y, and part of transition metal atom M is replaced with Al or Ga in 70 at% -13 to # 3-26 were produced. These cells were tested in the same manner as in Example 1. The results are shown in cells # 3-13 to # 3-26 in Table 3. All of them show better characteristics than Comparative Example Cell # 1-0.

＊セル＃３−１〜セル＃３−２６におけるセリア系ペロブスカイト型酸化物の置換量は５０ｗｔ％である。
＊８００℃で測定。 Table 3 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 3

* The substitution amount of the ceria-based perovskite oxide in the cell # 3-1 to the cell # 3-26 is 50 wt%.
* Measured at 800 ° C.

  A sol-gel solution mixed with the composition described in the column of impregnation in Table 4 in the same cell as the cell # 1-0 as a comparative example in Example 1 (5 wt% metal in a mixed solution of organometallic solution) Cell # 4-1 to cell # 4-51 were produced by impregnating by dripping from the surface of the fuel electrode, which is a porous body, and dried and fired at 1000 ° C. for 2 hours. The same measurement was performed. The results are shown in Table 4. Here, the cell # 4-0 is a cell which is only baked at 1000 ° C. without impregnation.

  All of them show better characteristics than Comparative Example Cell # 4-0.

Table 4 Composition of anode and electrode active oxide and anode overvoltage in Example 4

＊８００℃で測定。 Table 4 continued

* Measured at 800 ° C.

A cell # 5-0 using a ceria-based electrolyte SDC (Ce _0.8 Sm _0.2 O ₂ ) instead of the SASZ electrolyte of Example 1 and using SDC instead of YSZ of the fuel electrode of Example 1 is manufactured. did. Here, the firing temperature of the fuel electrode was 1300 ° C. for 2 hours. This cell is used as a comparative example when SDC is used as an electrolyte. Then a part of the SDC of the fuel electrode _Ce 1.0 _Fe x _{O 3} or _Ce 1.0 _Co x _{O 3} or _{Ce 1.0 Mn x O 3 (X} = 0.6,1.0,1.5 ) Or 50 wt% substitution with Ce _0.8 Sm _0.2 Fe _1.0 O ₃ to prepare a similar cell. This is designated as cell # 5-1 to cell # 5-14. The overvoltage characteristics of these cells were measured in the same manner as in Example 1. However, the measurement temperature was 700 ° C. The results are shown in cells # 5-1 to # 5-10 in Table 5-1. Both show better characteristics than Comparative Example Cell # 5-0.

＊セル＃５−１〜セル＃５−６におけるセリア系ペロブスカイト型酸化物の置換量は５０ｗｔ％である。
＊７００℃で測定。 Table 5-1 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 5

* The substitution amount of the ceria-based perovskite oxide in cell # 5-1 to cell # 5-6 is 50 wt%.
* Measured at 700 ° C.

Next, Ce _1.0 Fe _x O ₃ , or Ce _1.0 Co _x O ₃ , or Ce _1.0 Co _x O ₃ , or a cell produced under the same conditions as in cell # 5-0 as a comparative example, Ce _1.0 Mn _x O ₃ (X = 0.6, _1.0, 1.5), or a part of Ce in these compositions is replaced with Ca, Sm, or Gd, and Fe, Co, Mn A sol-gel solution corresponding to the composition in which the part was replaced with Al or Ga was prepared, impregnated with these, dried, and then fired at 1000 ° C. for 2 hours to produce Cell # 5-11 to Cell # 5-37. The same measurement was performed at ° C. The results are shown in Table 5-2. Both show better characteristics than Comparative Example Cell # 5-0.

＊７００℃で測定。 Table 5-2 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 5

* Measured at 700 ° C.

A lanthanum gallate electrolyte LSGM (La _0.8 Sr _0.2 Ga _0.85 Mg _0.15 O ₃ ) was used instead of the SASZ electrolyte of Example 1, and SDC was replaced with YSZ of the fuel electrode of Example 1. Cell # 6-0 used was fabricated. Here, the firing temperature of the fuel electrode was 1300 ° C. for 2 hours. This cell is used as a comparative example when LSGM is used as an electrolyte. Then a part of the SDC of the fuel electrode _Ce 1.0 _Fe x _{O 3} or _Ce 1.0 _Co x _{O 3} or _{Ce 1.0 Mn x O 3 (X} = 0.6,1.0,1.5 ) To obtain a similar cell. This is designated as cell # 6-1 to cell # 6-9. The overvoltage characteristics of these cells were measured in the same manner as in Example 1. However, the measurement temperature was 700 ° C. These results are shown in cells # 6-1 to # 6-9 in Table 6-1. All of them show better characteristics than Comparative Example Cell # 6-0.

＊セル＃６−１〜セル＃６−９におけるセリア系ペロブスカイト型酸化物の置換量は５０ｗｔ％である。
＊７００℃で測定。 Table 6-1 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 6

* The replacement amount of the ceria-based perovskite oxide in cell # 6-1 to cell # 6-9 is 50 wt%.
* Measured at 700 ° C.

Next, Ce _1.0 Fe _x O ₃ , or Ce _1.0 Co _x O ₃ , or Ce _1.0 Co _x O ₃ , or a cell produced under the same conditions as in cell # 6-0 as a comparative example, A sol-gel solution corresponding to the composition of Ce _1.0 Mn _x O ₃ (X = 0.6, _1.0, 1.5) is prepared, and a part of Ce in these compositions is Ca, Sm, or Gd. Sol-gel solution corresponding to the composition in which a part of Fe, Co, and Mn is replaced with Al or Ga is prepared, impregnated with these, dried, fired at 1000 ° C. for 2 hours, and cell # 6- 10-cell # 6-33 was produced and the same measurement was performed at 700 degreeC. The results are shown in Table 6-2. All of them show better characteristics than Comparative Example Cell # 6-0.

＊７００℃で測定。 Table 6-2 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 6

* Measured at 700 ° C.

By dripping the sol-gel solution corresponding to the composition of cell # 4-13 and cell # 4-19 from the surface of the fuel electrode, which is a porous body, into the same cell as cell # 1-0, which is a comparative example in Example 1. After impregnation, drying, and baking at 1000 ° C. for 2 hours, cell # 7-1 to cell # 7-15 were produced, and the same measurement as in Example 1 was performed. In Examples 4 and 5, impregnation was performed twice using a 5 wt% solution, and 5 wt% ceria-based perovskite oxide was added to the entire fuel electrode. By diluting with toluene, a cell with a low addition amount was produced, and for addition amounts beyond this, the number of impregnations was further increased. Next, the addition amount was fixed to 5 wt%, and the ratio of ceria to transition metal was changed to the composition ratio shown in cell # 7-16 to cell # 7-21 in Table 7 to cell # 7-16 to cell # 7 -21 was produced.
These measurement results are shown in Table 7. Here, the cell # 7-0 is a cell which is only baked at 1000 ° C. without impregnation.

  All of them show better characteristics than Comparative Example Cell # 1-0.

＊８００℃で測定。 Table 7 Fuel electrode and electrode active oxide composition and fuel electrode overvoltage in Example 7

* Measured at 800 ° C.

  According to the present invention, by using a fuel electrode for SOFC containing a ceria-based perovskite oxide as a fuel electrode of a solid oxide fuel cell, generation of a pyrochlore phase that leads to deterioration of the characteristics of the fuel electrode, carbon deposition, and carbon dioxide We succeeded in obtaining a cell with high electrode performance without causing instability. The present invention greatly contributes to improving the efficiency of solid fuel cells.

The schematic diagram of the single cell used in the Example. The figure which shows the structure of the single cell and fuel cell in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid electrolyte 2 Fuel electrode 3 Air electrode 4 Current collection mesh 5 Platinum terminal 6 Reference electrode 7 Gas seal

Claims (14)

In a fuel electrode of a fuel cell comprising a dense zirconia-based solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode is And a cermet of an oxide and a metal, which is a mixture of a zirconia-based electrolyte material and a ceria-based perovskite oxide, and the composition of the ceria-based perovskite-type oxide is represented by the following formula (in CeM _x O ₃ , M is Cr, A ceria-based perovskite oxide characterized in that it is one or more metal elements selected from V, Mn, Fe, and Co, and the total amount X is represented by 0.6 < X < 1.5) Including SOFC fuel electrode. In a fuel cell comprising a dense ceria-based solid electrolyte, a fuel cell comprising a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode is ceria-based. This is a cermet of a mixture of an electrolyte material and an oxide that is a mixture of a ceria-based perovskite oxide and a metal, and the composition of the ceria-based perovskite oxide is represented by the following formula (in CeM _x O ₃ , M is Cr , V, Mn, Fe, Co, a ceria-based perovskite oxide characterized in that the total amount X is represented by 0.6 < X < 1.5). SOFC fuel electrode including In a fuel electrode of a fuel cell comprising a dense lanthanum gallate solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode Is a cermet of an oxide and a metal, which is a mixture of a ceria-based electrolyte material and a ceria-based perovskite oxide, and the composition of the ceria-based perovskite oxide is represented by the following formula (in CeM _x O ₃ , M is Cr , V, Mn, Fe, Co, a ceria-based perovskite oxide characterized in that the total amount X is represented by 0.6 < X < 1.5). SOFC fuel electrode including In the CeM _x O ₃ , a part of M is substituted with one or more elements selected from Al and Ga, and a part of Ce is Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb. , Lu, and Y. At this time, the total substitution amount of atoms replacing Ce is 50% or less, and the total substitution amount of M is less than 50% ([Ce _{1 -Z Ln Z] [M 1-} Y M1 Y] X; Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 The ceria-based perovskite according to any one of claims 1 to 3, wherein = Al; Ga; Z < 0.5; Y <0.5; 0.6 < X < 1.5). Fuel electrode for SOFC containing type oxide. In the CeM _x O ₃ , a part of M is replaced with one or more elements selected from Al and Ga, and a part of Ce is replaced with Ca, Sr, Nd, Sm, Gd, Eu, Tb, Dy. , Ho, Er, Yb, Lu, Y are substituted with one or more elements. At this time, the total substitution amount of atoms substituting Ce is 50% or less, and the total substitution amount for M is 50 % or more and 90% or less, and _{([Ce 1-Z Ln Z} ] [M 1-Y M1 Y] X; Ln = Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; 0.5 < Y < 0.9; 0.6 < X < 1.5). The SOFC containing the ceria-based perovskite oxide according to any one of claims 1 to 3, Fee poles. In a fuel electrode of a fuel cell comprising a dense zirconia-based solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode is The cermet is composed of a cermet of oxide and metal, which is a mixture of zirconia-based electrolyte material and ceria-based perovskite-type oxide, and the ceria-based perovskite-type oxide is fine on the surface of the mixture of zirconia-based electrolyte material and metal. The ceria-based perovskite oxide is covered with particles and the content of the ceria-based perovskite oxide is 15 wt% or less in the fuel electrode, and the ceria-based perovskite-type oxide is added after the firing of the fuel electrode and the electrolyte, and the composition of the ceria-based perovskite oxide is the following formula (M is at _{CeM x O 3 Cr, V,} Mn, Fe, C One or more of metal elements, SOFC fuel electrode to which the total amount X comprises a ceria-based perovskite oxide is characterized by being represented by 0.1 <X <1.5) is selected from among. In a fuel electrode of a fuel cell comprising a dense ceria-based solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode is The cermet of oxide and metal, which is a mixture of ceria-based electrolyte material and ceria-based perovskite-type oxide, and the ceria-based perovskite-type oxide is fine on the surface of the mixture of ceria-based electrolyte material and metal The ceria-based perovskite oxide is covered with particles and the content of the ceria-based perovskite oxide is 15 wt% or less in the fuel electrode, and the ceria-based perovskite-type oxide is added after the firing of the fuel electrode and the electrolyte, and the composition of the ceria-based perovskite oxide is the following formula (M is at _{CeM x O 3 Cr, V,} Mn, Fe, selected from among Co One or more of metal elements, SOFC fuel electrode to which the total amount X comprises a ceria-based perovskite oxide is characterized by being represented by 0.1 <X <1.5) to. In a fuel electrode of a fuel cell comprising a dense lanthanum gallate solid electrolyte, a porous fuel electrode and an air electrode provided on both sides thereof, and an interconnector for electrically connecting them, the fuel electrode Is composed of a cermet of an oxide and a metal, which is a mixture of a ceria-based electrolyte material and a ceria-based perovskite-type oxide, and the ceria-based perovskite-type oxide is fine on the surface of the mixture of the ceria-based electrolyte material and the metal. And the ceria-based perovskite oxide content is 15 wt% or less in the fuel electrode, and the ceria-based perovskite oxide is added after the firing of the fuel electrode and the electrolyte, and , M in the composition following formula ceria-based perovskite type oxide _{(CeM x O 3 Cr, V} , Mn, Fe, Co One or more of metal elements, SOFC fuel electrode to which the total amount X comprises a ceria-based perovskite oxide is characterized by being represented by 0.1 <X <1.5) is selected from among. In the CeM _x O ₃ , a part of M is substituted with one or more elements selected from Al and Ga, and a part of Ce is Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb. , Lu, and Y. At this time, the total substitution amount of M is less than 50%, and the total substitution amount of atoms substituting Ce is 50% or less ([Ce _{1-z Ln z] [M} 1-Y M1 Y] x; Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; The ceria-based perovskite according to any one of claims 6 to 8, wherein M1 = Al, Ga; Z < 0.5; Y <0.5; 0.1 < X < 1.5). Fuel electrode for SOFC containing type oxide. In the CeM _x O ₃ , a part of M is replaced with one or more elements selected from Al and Ga, and a part of Ce is replaced with Ca, Sr, Sm, Eu, Gd, Tb, Dy, and Ho. , Er, Yb, Lu, Y is substituted with one or more elements selected from the group consisting of M, the total substitution amount of M being 50% or more and 90% or less, and the total substitution amount of atoms substituting Ce There than 50% _{([Ce 1-z Ln z} ] [M 1-Y M1 Y] x; Ln = Ca, Sr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y; M = Cr, V, Mn, Fe, Co; M1 = Al, Ga; Z < 0.5; 0.5 < Y < 0.9; 0.1 < X < 1.5) A fuel electrode for SOFC comprising the ceria-based perovskite oxide according to any one of claims 6 to 8. 11. The method for producing a fuel electrode according to claim 6, 9, or 10, wherein a slurry of the zirconia-based electrolyte material and a metal is applied onto the zirconia-based electrolyte and sintered, and then a ceria-based perovskite oxide solution. A method for producing a fuel electrode for SOFC containing a ceria-based perovskite oxide, characterized by comprising adding and firing. 11. The method for producing a fuel electrode according to claim 7, 9, or 10, wherein a slurry of the ceria-based electrolyte material and a metal is applied on the ceria-based electrolyte and sintered, and then a ceria-based perovskite oxide solution. A method for producing a fuel electrode for SOFC containing a ceria-based perovskite oxide, characterized by comprising adding and firing. 11. The method for producing a fuel electrode according to claim 8, 9, or 10, wherein a slurry of the ceria-based electrolyte material and a metal is applied and sintered on the lanthanum gallate electrolyte, and then the ceria-based perovskite oxide is formed. A method for producing a fuel electrode for SOFC containing a ceria-based perovskite oxide, characterized by adding a solution and calcining. The method for producing a fuel electrode for SOFC containing a ceria-based perovskite oxide according to any one of claims 11 to 13, wherein the solution is a sol-gel solution of a ceria-based perovskite oxide.

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