JP2006172946A - Solid electrolyte fuel battery cell, and solid electrolyte fuel battery using it and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel battery cell with a specific metallized layer, and to provide a solid electrolyte fuel cell having a structure where this metallized layer and a segregation separator are brazed and a method of manufacturing it. <P>SOLUTION: This cell includes a solid electrolyte layer 11, a fuel electrode 12 provided in one surface of the solid electrolyte layer 11, an air pole 13 which is provided on the other surface of the solid electrolyte layer 11, and a metallized layer 141 provided in the one surface or the other surface of the peripheral edge of this solid electrolyte layer 11. The fuel cell has a structure where the cell is connected through an inter-connector. Each cell has a segregation member which isolates a passage for introducing combustion supporting gas into the passage and an air pole for introducing the fuel gas into the fuel electrode. The metallized layer and the isolation member provided in each solid electrolyte layer are connected by a metal brazing material, respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell, a solid electrolyte fuel cell using the same, and a method for manufacturing the same. More specifically, the present invention relates to a solid electrolyte layer cell including a metallized layer provided at a peripheral portion of the solid electrolyte layer by a method that does not cause deterioration in performance of a member such as an air electrode, and the metallized layer and the separating member. The present invention relates to a solid oxide fuel cell in which the flow path of the fuel gas and the flow path of the combustion-supporting gas are separated by brazing and the manufacturing method thereof.

  A solid electrolyte fuel cell (hereinafter also referred to as “fuel cell”) is formed by stacking a plurality of cells using an interconnector. In this fuel cell, a gas seal for isolating the flow path of the fuel gas supplied to the fuel electrode and the flow path of the combustion-supporting gas supplied to the air electrode is provided. Each channel can be isolated by joining a solid electrolyte layer and an isolation member for isolating each channel.

  In recent years, studies have been made to operate a fuel cell in a relatively low temperature range of 800 ° C. or lower by reducing the internal resistance by making a solid electrolyte layer made of yttria stabilized zirconia or the like as thin as possible. In particular, when operating in such a low temperature range, it is possible to use metal isolation members and interconnectors instead of ceramics, and use inexpensive stainless steel isolation members or the like to reduce costs. You can also. The joining of the isolation member or the like can be performed by a method using an active brazing material and a method of forming a metallized layer on the surface of the solid electrolyte layer and then brazing the metallized layer and the isolation member (for example, , See Patent Document 1).

JP 2004-146129 A

  However, as an activator to be blended in the active brazing material, metal elements such as Ti and Zr are usually used. Since Ti and Zr and the like are easily oxidized metals, an active brazing material was used. Bonding is generally performed in an atmosphere of high vacuum and low oxygen partial pressure. However, in such an atmosphere, depending on the material of the member to be joined, the atmosphere during joining may not be maintained at a sufficiently high vacuum and low oxygen partial pressure, and in this case, the active brazing material may not function effectively. There is.

  Furthermore, a method of forming a metallized layer on the surface of the solid electrolyte layer is also common, and although there are various methods of metallization, it is assumed that the joint has heat resistance and that the air electrode is not decomposed, Is not easy. For example, in Patent Document 1, a technique of coating a metal on the solid electrolyte layer is used. There are various methods for coating this metal. In Patent Document 1, metallization is performed by a so-called Mo-Mn method. However, in this Mo-Mn method, heat treatment is generally performed at a high temperature of about 1400 ° C. in a humidified hydrogen atmosphere, and since the air electrode is easily decomposed in this atmosphere, the fuel cell having sufficient power generation performance It is difficult to do.

  Moreover, in the film formation by CVD, the actual film formation amount with respect to the target to be used is very small, which is not a preferable method from the viewpoint of cost and mass production. Furthermore, there is a method of forming a metal such as Kovar on the surface of the solid electrolyte layer, but this is not preferable because the heat resistance is not sufficient. In addition, film formation by electroless plating requires complicated masking, and there is a problem that members such as an air electrode are eluted during acid treatment. Furthermore, there is a method of metallizing using a material in which silica or the like is mixed with a metal, but it is difficult to firmly join the silica or the like because the silica or the like hardly penetrates into the grain boundary of the dense and high-purity solid electrolyte layer.

  The present invention has been made in view of the above situation, and a solid electrolyte fuel cell including a metallized layer provided by a method that does not cause deterioration in the performance of a member such as an air electrode at the periphery of the solid electrolyte layer By brazing the cell and the metallized layer and the separating member, a bonding layer having high heat resistance and sufficient bonding strength can be formed, whereby the fuel gas flow path and the combustion-supporting gas can be formed. It is an object of the present invention to provide a solid oxide fuel cell in which the flow path is isolated and a method for manufacturing the same.

The present invention is as follows.
1. A solid electrolyte layer 11, a fuel electrode 12 provided on one surface of the solid electrolyte layer 11, an air electrode 13 provided on a portion of the other surface of the solid electrolyte layer 11 excluding the peripheral edge, and the solid electrolyte In the solid oxide fuel cell comprising the metallized layer 141 provided on the peripheral edge of the one surface or the other surface of the layer 11, the metallized layer 141 is made of a mixture of a metal and a metal oxide. A solid oxide fuel cell characterized by the above.
2. The metal is at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W and In. The solid oxide fuel cell described in 1.
3. The solid electrolyte layer 11 is made of a ZrO ₂ ceramic, and the metal oxide is at least one of ZrO ₂ , MgO, CaO, and a rare earth element oxide. Or 2. The solid oxide fuel cell described in 1.
4). When the mixture is 100% by mass, the metal is 60 to 99% by mass, and the metal oxide is 1 to 40% by mass. To 3. The solid oxide fuel cell according to any one of the above.
5. Above 1. To 4. A solid oxide fuel cell having a structure in which the solid oxide fuel cells according to any one of the above are connected via an interconnector 21, each of the solid electrolyte fuel cells being one The isolation member 22 is joined to the solid electrolyte layer 11 and isolates the flow path for introducing the fuel gas into the fuel electrode 12 and the flow path for introducing the combustion-supporting gas into the air electrode 13. A solid electrolyte fuel cell characterized in that the metallized layer 141 provided on each solid electrolyte layer 11 and the separating member 22 are joined by a metal brazing material.
6). 5. above. A method for producing a solid electrolyte fuel cell according to claim 1, wherein a laminating step of laminating an unsintered air electrode or an unsintered fuel electrode and one surface of the unsintered solid electrolyte layer, and a method of forming the other surface of the unsintered solid electrolyte layer A coating film forming step for forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral edge, the unsintered air electrode or the unsintered fuel electrode, and the unsintered solid electrolyte layer A co-firing step of integrally firing the metallized coating film, and forming an unfired fuel electrode or an unfired air electrode on the other surface of the solid electrolyte layer 11 formed by firing the unfired solid electrolyte layer, and then firing The fuel electrode or air electrode manufacturing step for manufacturing the fuel electrode 12 or the air electrode 13 and the reducing metal oxide contained in the metallized layer 141 formed by firing the metallized coating film are reduced to reduce the metal. A reduction step to be produced, and the metallization Joining step and a method for producing a solid electrolyte fuel cell characterized by comprising in this order a layer 141 and the isolation member 22 are joined by brazing filler metal.
7). 5. above. The solid electrolyte fuel cell manufacturing method according to claim 1, wherein the solid electrolyte layer is prepared by firing an unfired solid electrolyte layer, and an unsintered air electrode on one surface of the solid electrolyte layer 11. Or a non-fired air electrode provided with a non-fired fuel electrode and forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral edge of the other surface of the unfired solid electrolyte layer, or An unsintered fuel electrode / metallized coating film forming step, a firing step of firing the unsintered air electrode or the unsintered fuel electrode and the metallized coating film, an unsintered fuel electrode or A fuel or air electrode production step of forming an unfired air electrode and then firing to produce the fuel electrode 12 or the air electrode 13 and the reduction contained in the metallized layer 141 formed by firing the metallized coating film Reducing the functional metal oxide A reduction step to produce the metal, the bonding step and, a method for producing a solid electrolyte fuel cell characterized by comprising in this order to the said metallized layer 141 and the isolation member 22 are joined by brazing filler metal.
8). 5. above. A method for producing a solid electrolyte fuel cell according to claim 1, wherein the unsintered air electrode or unsintered fuel electrode and one surface of the unsintered solid electrolyte layer are stacked, the unsintered air electrode or the unsintered fuel. A co-firing step of integrally firing the electrode and the unsintered solid electrolyte layer, and a reducing metal oxide and a non-reducing property on the peripheral portion of the other surface of the solid electrolyte layer 11 formed by firing the unsintered solid electrolyte layer A metallized coating film containing a metal oxide is formed and then fired to form a metallized layer 141, and an unsintered fuel electrode or unsintered air electrode is formed on the other surface of the solid electrolyte layer 11. Forming and then firing to produce a fuel electrode 12 or an air electrode 13, and a reductive metal oxide contained in the metallized layer 141 to reduce a metal oxide reduced product. Reduction step to be generated and the method Joining step and a method for producing a solid electrolyte fuel cell characterized by comprising in this order to a rise layer 141 and the isolation member 22 are joined by brazing filler metal.
9. The reducible metal oxide contains at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. To 8. The manufacturing method of the solid oxide form fuel cell of any one of these.
10. The above reduction step is performed in a reducing atmosphere containing 500 to 1000 ° C. and 0.01 to 7% by mass of hydrogen, with the balance being nitrogen or an inert gas. To 9. The manufacturing method of the solid oxide form fuel cell of any one of these.

The solid electrolyte fuel cell of the present invention includes a metallized layer 141 provided by a method that does not cause a performance degradation of a member such as an air electrode, and maintains good power generation performance.
Further, when the metal is at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In, a metallized layer having sufficient conductivity can be obtained.
Furthermore, when the solid electrolyte layer 11 is made of ZrO ₂ -based ceramic and the metal oxide is at least one of ZrO ₂ , MgO, CaO and rare earth element oxide, the solid electrolyte layer 11 and the metallized layer 141 It is possible to improve the bonding strength.
Moreover, when a mixture is 100 mass%, when a metal is 60-99 mass% and a metal oxide is 1-40 mass%, it can be set as the metallization layer which has sufficient electroconductivity.
In the solid oxide fuel cell of the present invention, the solid electrolyte layer and the separating member are joined by the joining layer 14 having high heat resistance and sufficient joining strength, so that sufficient power generation performance is maintained.
According to the method for producing a solid electrolyte fuel cell of the present invention, the method for producing another solid electrolyte fuel cell of the present invention, and the method for producing another solid electrolyte fuel cell of the present invention, the solid electrolyte layer is isolated from the solid electrolyte layer. The member can be strongly bonded, a bonding layer having high heat resistance can be formed, and a fuel cell in which sufficient power generation performance is maintained can be easily obtained. The fuel cell manufacturing method of the present invention and still another fuel cell manufacturing method of the present invention are particularly useful for manufacturing a fuel electrode-supporting fuel cell described later, and manufacturing of another fuel cell of the present invention. The method is particularly useful for the production of a self-supporting fuel cell as described below.
Further, when the reducing metal oxide contains at least one metal element of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W and In, the reducing metal oxide is It is easily reduced to produce metal, and the solid oxide fuel cell and the separating member can be firmly joined, and sufficient power generation performance is maintained.
Further, when the reduction step is performed in a reducing atmosphere containing 500 to 1000 ° C. and 0.01 to 7% by mass of hydrogen and the balance being nitrogen or an inert gas, the reducing metal oxide is sufficiently The fuel cell is reduced and the air electrode or the like is not decomposed, and the fuel cell has sufficient power generation performance.

Hereinafter, the present invention will be described in detail with reference to FIGS.
[1] Solid electrolyte fuel cell and solid electrolyte fuel cell using the same (1) Solid electrolyte fuel cell The above "solid electrolyte fuel cell" (hereinafter also referred to as "cell"). The solid electrolyte layer 11, the fuel electrode 12 provided on one surface of the solid electrolyte layer 11, the air electrode 13 provided on the other surface, and the peripheral surface of one surface or the other surface of the solid electrolyte layer 11. And a metallized layer 141. The structure of this cell is not particularly limited. For example, as shown in FIGS. 1 and 4 to 5, the solid electrolyte layer 11, the fuel electrode 12, and the air electrode 13 are all plate-shaped cells 1011 that are in the form of sheets. be able to. Furthermore, it can also be set as the flat cylindrical cell 1012 like FIG. 6, and it can also be set as the cylindrical cell 1013 like FIG.

  In the flat cylindrical cell 1012 of FIG. 6, the fuel electrode 12 is formed inside through the solid electrolyte layer 11 and the air electrode 13 is formed outside, but the air electrode 13 is formed inside and the fuel electrode 12 is formed outside. Others can be cells having the same structure. Further, the cylindrical cell 1013 having a circular cross section in FIG. 9 can have the same structure as the above flat cylindrical type except that it is a cylindrical type. Further, in FIG. 9, the air electrode 13 is formed inside through the solid electrolyte layer 11 and the fuel electrode 12 is formed outside, but the same structure except that the fuel electrode 12 is formed inside and the air electrode 13 is formed outside. It can also be a cell.

  The “solid electrolyte layer 11” has ion conductivity that can move a part of one of the fuel gas introduced into the fuel electrode or the combustion-supporting gas introduced into the air electrode during the operation of the battery as ions. Have Although what kind of ion can be conducted is not particularly limited, examples of the ion include oxygen ion and hydrogen ion. The “fuel electrode 12” is in contact with a fuel gas serving as a hydrogen source and functions as a negative electrode in the cell. Further, the “air electrode 13” is in contact with a combustion-supporting gas serving as an oxygen source and functions as a positive electrode in the cell.

The material used for forming the solid electrolyte layer 11 can be appropriately selected depending on the use conditions of the fuel cell. Examples of this material include ZrO ₂ ceramics, LaGaO ₃ ceramics, BaCeO ₃ ceramics, SrCeO ₃ ceramics, SrZrO ₃ ceramics, and CaZrO ₃ ceramics. Among these materials, preferably ZrO ₂ based ceramic, Sc, Y and at least ZrO ₂ based ceramic is preferably stabilized by one of rare earth elements, stabilized ZrO ₂ based ceramic is particularly the Sc preferable.
The thickness of the solid electrolyte layer can be set to 100 to 500 μm, particularly 100 to 300 μm, and more preferably 100 to 150 μm when the fuel cell is a self-standing type described later in consideration of electric resistance and strength. When it is a fuel electrode support type or an air electrode support type described later, it can be set to 5 to 100 μm, particularly 5 to 50 μm, and further 5 to 30 μm.

The material used to form the “fuel electrode 12” can also be appropriately selected depending on the use conditions of the fuel cell. Examples of this material include metals such as Ni and Fe, and ZrO ₂ ceramics such as zirconia stabilized by at least one of Sc, Y and rare earth elements, CeO ₂ ceramics, and ceramics such as manganese oxides. And a mixture with at least one of them. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned. These metals may be used alone or in an alloy of two or more metals. Furthermore, a mixture (including cermet) of these metals and / or alloys and at least one of each of the above ceramics may be mentioned. Moreover, the mixture of metal oxides, such as Ni and Fe, and at least 1 type of each of the said ceramic etc. are mentioned. Among these materials, a mixture of a metal such as Ni and Fe and at least one of each of the ceramics is preferable, and a mixture of Ni and Sc stabilized with a ZrO ₂ ceramic is particularly preferable.
The shape of the fuel electrode is not particularly limited, but may be a flat plate shape, a flat cylindrical shape, a cylindrical shape or the like as described above. Moreover, when it is a flat type cell, it is preferable that a fuel electrode is the same planar shape as a solid electrolyte layer and an air electrode. The fuel electrode and the solid electrolyte layer are preferably laminated on substantially the entire surface.

The material used to form the “air electrode 13” can also be appropriately selected depending on the use conditions of the fuel cell. As this material, for example, various metals, metal oxides, metal double oxides, and the like can be used. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh, or alloys containing two or more metals. Examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn, and Fe (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO _2, FeO, and the like). It is done. Furthermore, as the double oxide, a double oxide containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based double oxide, La _1-x Sr _x FeO ₃ -based double oxide, La _1-x Sr _x Co _1-y Fe _y O ₃ -based double oxide, La _1-x Sr _x MnO ₃ -based double oxide, Pr _1-x Ba _x CoO ₃ -based double oxide Oxides and Sm _1-x Sr _x CoO ₃ -based double oxides).

Preferably mixed oxide Of _{these, Ln 1-x M x CoO} 3 -based mixed _{oxide, Ln 1-x M x FeO} 3 -based mixed oxide and _{Ln 1-x M x Co 1} -y Fe y O 3 More preferred are system double oxides (Ln is a rare earth element and M is Sr or Ba). The air electrode 13 composed of these Co and / or Fe-containing double oxides, particularly Co and Fe-containing double oxides, operates the SOFC at a low temperature in the temperature range of 500 to 850 ° C., and further 500 to 750 ° C. Even if it is, it has excellent performance as an electrode. These double oxides may further contain other substitution elements in addition to the Ln element and the M element. These _{Ln 1-x} M x CoO _3-based mixed _oxide, among Ln _1-x M x FeO _3-based mixed oxide and _{Ln 1-x M x Co 1} -y Fe y O 3 based mixed oxide, Ln _1-x M _x CoO _{3 ± δ} , Ln _1-x M _x FeO _{3 ± δ} and Ln _1-x M _x Co _1-y Fe _y O _{3 ± δ} , 0.2 ≦ x ≦ 0. 8, 0.5 ≦ y ≦ 0.9 and 0 ≦ δ <1 (δ is oxygen excess or oxygen deficiency) is particularly preferable, and Ln is selected from La, Pr and Sm. More preferably, it is at least one of the above. Examples of such Ln _1-x M _x CoO ₃ -based double oxides include La _0.6 Sr _0.4 CoO _{3 ± δ} , Pr _0.5 Ba _0.5 CoO _{3 ± δ} and Sm _0.5. Sr _0.5 CoO _{3 ± δ and the} like. Examples of the Ln _1-x M _x FeO ₃ -based complex oxide include La _0.6 Sr _0.4 FeO _{3 ± δ} , Pr _0.5 Ba _0.5 FeO _{3 ± δ} and Sm _0.5 Sr. _0.5 FeO _{3 ± δ and the} like. _Furthermore, as the _{Ln 1-x M x Co 1} -y Fe y O 3 based mixed oxide, for _{example, La 0.6 Sr 0.4 Co 0.2 Fe} 0.8 O 3 ± δ, Pr 0.5 Ba _0.5 Co _0.2 Fe _0.8 O _{3 ± δ,} Sm _0.5 Sr _0.5 Co _0.2 Fe _0.8 O _{3 ± δ and the} like.

  The shape of the air electrode is not particularly limited, but may be a flat plate shape, a flat cylindrical shape, a cylindrical shape or the like as described above. Moreover, when it is a flat type cell, it is preferable that an air electrode is the same planar shape as a solid electrolyte layer and a fuel electrode.

The “metallized layer 141” is made of a mixture of a metal and a metal oxide.
The “metal” is not particularly limited as long as a metallized layer having sufficient conductivity can be formed. This metal may be only one kind or two or more kinds. It is preferable that this metal is capable of forming the metallized layer 141 without causing a decrease in performance of members constituting the fuel cell such as an air electrode. This metal is preferably a metal containing 500 to 1000 ° C. and 0.01 to 7% by mass of hydrogen, with the balance being produced by reduction of the metal oxide under the condition of nitrogen or an inert gas. This temperature is preferably 550 to 950 ° C, particularly 600 to 850 ° C, and more preferably 650 to 750 ° C. The hydrogen content is preferably 0.05 to 5% by mass, particularly 0.1 to 4% by mass, and more preferably 0.5 to 3% by mass. The metal oxide (reducible metal oxide) reduced under such reducing conditions is not particularly limited as long as it is reduced under the above conditions to generate a metal. Examples of the reducing metal oxide include Fe ₂ O ₃ , Co ₃ O ₄ , NiO, CuO, and MoO _3. These are reduced and metals such as Fe, Co, Ni, Cu, and Mo are reduced. Generate.

As the reducible metal oxide, SnO ₂ , ZnO, and WO ₃ can be used in addition to the above various metal oxides, and these are reduced to produce metals such as Sn, Zn, and W. Moreover, examples of the reducible metal oxide containing two or more kinds of metal elements include double oxides such as CuFe ₂ O ₄ , CuMoO _4, and CuWO ₄ , and these are reduced to a mixture of Cu and Fe. A metal such as a mixture or alloy of Cu and Mo and a mixture or alloy of Cu and W is formed. Furthermore, as a reducible metal oxide, a mixture of metal oxides such as CuO and NiO, and NiO and Co ₃ O ₄ can be used, and these are reduced to a mixture or alloy of Cu and Ni, and Ni A mixture or alloy of Co and Co is produced.

The “metal oxide” is not particularly limited. However, when the metal is generated by reducing the reducible metal oxide, the metal oxide is not reduced under the above conditions and is maintained as the metal oxide. Preferably, it is a non-reducing metal oxide. The metal element contained in the non-reducing metal oxide may be only one type or two or more types. The non-reducible metal oxide is preferably a metal oxide that is not reduced under the above conditions and that can improve the bondability between the solid electrolyte layer 11 and the metallized layer 141. In order to improve the bondability in this way, it is preferable that at least a part of the metal element contained in the solid electrolyte layer 11 and the metal element contained in the non-reducing metal oxide are the same type, It is more preferable that the metal elements are the same. Furthermore, the non-reducing metal oxide 1411 (see FIG. 2) preferably contains a metal element that can be dissolved in the ceramic constituting the solid electrolyte layer 11. For example, when the solid electrolyte layer 11 is made of a ZrO ₂ ceramic, it is preferable that the non-reducing metal oxide 1411 is at least one of ZrO ₂ , MgO, CaO, and a rare earth element oxide. Since ZrO ₂ is the same type, the bondability can be improved, and Mg, Ca, and rare earth elements can be dissolved in the ZrO ₂ ceramic, thereby improving the bondability.

The solid oxide fuel cell does not reduce the reducible metal oxide, and can be stored as an intermediate product having a metallization film made of a mixture of a reducible metal oxide and a non-reducible metal oxide. .
That is, a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, an air electrode provided on the other surface of the solid electrolyte layer, a metallization film provided on a peripheral portion of the solid electrolyte layer, In the solid electrolyte fuel cell having the above structure, the metallization film may be a solid oxide fuel cell characterized by comprising a mixture of a reducing metal oxide and a non-reducing metal oxide.

  In the case of this intermediate product, when it becomes necessary, the reducing metal oxide contained in the metallization film can be reduced to form a metallized layer, which can be used as a solid electrolyte fuel cell. If it does in this way, it can suppress that a metallization layer deteriorates by storage etc. and a joint property with an isolation member falls. In this intermediate product, for the solid electrolyte layer, the fuel electrode, the air electrode, the reducing metal oxide and the non-reducing metal oxide, the description of the solid electrolyte fuel cell of the present invention is applied as it is. be able to.

(2) Solid electrolyte fuel cell The above-mentioned “solid electrolyte fuel cell” includes, for example, a plurality of flat solid electrolyte fuel cells 1011 via interconnectors 211 and 212 as shown in FIGS. It can be formed by connection. Although this solid oxide fuel cell 102 depends on the cell structure, the isolation member 22 for isolating the flow path of the fuel gas and the flow path of the combustion-supporting gas (see FIG. 2, as shown in FIGS. 3 to 5) In the case of the flat plate type, hereinafter, the separators 221, 222, and 223), the nickel felt layer 31 for electrically connecting the interconnectors 211 and 212 and the fuel electrode 12, and the interconnectors 211 and 212 and air A current collecting member such as an Inconel fiber mesh layer 32 for electrically connecting the electrode 13 is provided.

  In addition, a solid electrolyte fuel cell can be formed using a flat cylindrical solid oxide fuel cell 1012 as shown in FIG. As shown in FIG. 7, this fuel cell is formed by connecting a plurality of flat cylindrical cells 1012 via interconnectors 213. Although this fuel cell depends on the battery structure, as shown in FIG. 8, the peripheral portion of the solid electrolyte layer 11 is separated from the periphery of the solid electrolyte layer 11 at the end of each cell (in the case of a flat cylindrical type as shown in FIG. The fuel gas introduction / separation member 224) is joined to form the joining layer 14, whereby each cell can be fixed. Each cell can be electrically connected by a current collecting member such as the interconnector 213 and the Inconel fiber mesh layer 32.

  In the fuel cell of FIG. 7, an isolation member (not shown) similar to the lower side is disposed on the upper side of the cell (this isolation member serves as a fuel gas discharge and isolation member). From the opening of the fuel gas introduction / separation member 224, the fuel gas is introduced into the through hole 121 provided in the fuel electrode 12 and circulated through the inside of the through hole 121, from the opening of the upper fuel gas discharge / separation member. It can be discharged. On the other hand, the combustion-supporting gas can be introduced into, circulated, and discharged into the external space of each cell (this space is a sealed space formed by a sealed container or the like covering all the cells). In this way, it can be operated as a fuel cell.

  In addition, in the flat cylindrical cell of FIG. 6, when the cells have the same structure except that the air electrode 13 is formed inside and the fuel electrode 12 is formed outside as described above, each cell depends on the battery structure. At the end of each cell, the peripheral edge of the solid electrolyte layer is joined to a supporting gas introducing / separating member as a separating member to form a joining layer, whereby each cell can be fixed. Furthermore, each cell can be electrically connected by a current collecting member such as an interconnector and a nickel felt layer, and a fuel cell can be obtained. This fuel cell introduces a combustion-supporting gas into a through-hole provided in the air electrode, distributes the inside of the through-hole, and discharges it from the opening of the upper combustion-supporting gas discharge / separation member, By introducing the fuel gas into the sealed space formed outside the cell, allowing it to flow, and discharging it, the fuel cell can be operated in the same manner as described above.

  Furthermore, a solid electrolyte fuel cell can be formed using a cylindrical solid oxide fuel cell 1013 as shown in FIG. This cell 1013 can be made into a fuel cell in the same manner as the cell 1012 by using a separating member, an interconnector 214, and a current collecting member such as a nickel felt layer and an Inconel fiber mesh layer. Can be operated.

  In the fuel cell 102 of FIGS. 3 to 5 using the flat plate cell 1011 of FIG. 1, the interconnectors 211 and 212, the separator separators 221, 222 and 223, and other members such as the lid member 23 and the bottom member 24 described later. Are formed of a heat-resistant metal such as stainless steel. In addition, in order to electrically insulate the respective cells, ceramic frame bodies 51, 52, 53 made of an insulating ceramic may be laminated at predetermined portions in the lamination direction to prevent a short circuit. In this solid electrolyte fuel cell 102, the metallized layer 141 and the separator separators 221, 222, and 223 are joined by a metal brazing material to form the joint layer 14, and the solid electrolyte layer, the separator separator, and the separator separator The interconnector and other members such as a metal frame, a ceramic frame, a lid member, and a bottom member are joined directly or indirectly by a metal brazing material to form a joint 4.

  Further, the fuel gas introduction / separation member 224 (see FIGS. 7 and 8) in the fuel cell using the flat cylindrical cell 1012 of FIG. 6 and the cylindrical cell 1013 of FIG. 9 is also formed of a heat-resistant metal such as stainless steel. Has been. The fuel gas introduction / separation member 224 may be formed of a conductive ceramic. In these fuel cells, the metallized layer and the fuel gas introduction / separation member 224 are joined by a metal brazing material to form a joining layer 14 (see FIG. 8). Directly or indirectly joined by a metal brazing material to form a joint.

The heat-resistant metal constituting the various separators and interconnectors is not particularly limited, and examples include stainless steel, nickel-base alloy, and chromium-base alloy. Examples of the stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS430, SUS434, and SUS405. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305. Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. The chromium-based alloys, Ducrlloy CRF (94 wt% Cr-5 wt% Fe-1 _wt% Y 2 _{O 3),} and the like. These various metals can be selected according to the structure of the solid oxide fuel cell.

Various separators and the like may be formed of a conductive ceramic. Examples of the conductive ceramic include LaCrO ₃ and MTiO ₃ (M is a metal element, and M is an alkaline earth such as Sr, Ca, Ba, etc. Metal)). These various conductive ceramics can be selected according to the structure of the solid oxide fuel cell, respectively.

Furthermore, the ceramic frame bodies 51, 52, and 53 need only have insulating properties, and are not particularly limited, but MgO, MgAl ₂ O ₄ , ZrO _2, Al ₂ O ₃ , a mixture thereof, and the like are used. There are many.

  The metal brazing material is not particularly limited, and a Ni-based metal brazing material (hereinafter referred to as “Ni-based brazing material”), an Ag-based metal brazing material (hereinafter referred to as “Ag-based brazing material”), and the like can be used. . As this metal brazing material, a Ni-based brazing material having better heat resistance is preferable. As this Ni-based brazing material, one containing Ni and B or P, and when the Ni-based brazing material is 100 mass%, a Ni content of 60 mass% or more can be used. The Ni content can be 70% by mass or more, and can be 80% by mass or more (when B is contained, it is usually 95% by mass or less, and when P is contained, it is usually 85 mass% or less). If the Ni content is 60% by mass or more, a sufficiently heat-resistant Ni-based brazing material can be obtained, and when the operating temperature is about 800 ° C, there is a portion where the temperature rises to near 900 ° C. However, it is possible to obtain a solid oxide fuel cell that can withstand even when operated at a higher temperature of 800 to 1000 ° C.

  The Ni-based brazing material may contain B or P in addition to Ni. By containing B or P, the fluidity is improved, the metallized layer 141 and the isolation separator 22 can be sufficiently adhered, and the bonding strength can be further increased. The content of B or P is not particularly limited, but when the metal brazing material is 100% by mass, in the case of B, 1 to 5% by mass, particularly 1.5 to 4% by mass, and further 2 to 3.5% by mass. %. If the content of B is 1 to 5% by mass, the flowability of the Ni-based brazing material can be sufficiently increased. Moreover, in the case of P, it can be 5-15 mass%, Especially 6.5-13.5 mass%, Furthermore, it can be 8-12 mass%. If the content of P is 5 to 15% by mass, the flowability of the Ni-based brazing material can be sufficiently increased.

  In addition to Ni and B or P, the Ni brazing material may further contain Cr. By containing an appropriate amount of Cr, the heat resistance of the Ni-based brazing material can be further increased. The content of Cr is not particularly limited, but can be 5 to 20% by mass, particularly 10 to 18% by mass, and further 12 to 16% by mass when the Ni brazing material is 100% by mass. If the content of Cr is 8 to 20% by mass, the heat resistance of the Ni-based brazing material can be sufficiently increased.

  An Ag-based brazing material can also be used as the metal brazing material. This Ag-based brazing material usually contains Pd. When the total amount of Ag and Pd is 100% by mass, Pd is contained in an amount of 2 to 10% by mass, particularly 3 to 7% by mass. If the content of Pd is 2 to 10% by mass, an Ag-based brazing material excellent in oxidation resistance and the like can be obtained, and a joint portion having sufficient durability can be formed. Furthermore, the Ag-based brazing material flows sufficiently at the time of joining, and the sealing performance of the joined portion can be improved.

  The Ag-based brazing material may further contain Cu. The content of each of Ag, Pd and Cu when Cu is contained is not particularly limited, but when the total of Ag, Pd and Cu is 100% by mass, the content of Ag is 45 to 65% by mass. In particular, it is preferable that the content of Pd is 50 to 60% by mass, the content of Pd is 15 to 35% by mass, particularly 20 to 30% by mass, and the content of Cu is 10 to 30% by mass, and particularly 15 to 25% by mass. When Cu is contained, even if it contains a larger amount of Pd than an Ag-based brazing material that does not contain Cu, it has sufficient fluidity and maintains excellent sealing properties. The total of Ag and Cu is preferably 65% by mass or more, that is, if the Pd content is 35% by mass or less, the Ag-based brazing material flows sufficiently and improves the sealing performance of the joint. Can be made.

  The Ag-based brazing material may further contain Ti. By containing an appropriate amount of Ti, particularly high bonding strength can be obtained even when the bonding temperature is relatively low. The content of Ti is when the total of Ag, Pd and Ti is 100% by mass, or when Cu is contained, the total of Ag, Pd, Cu and Ti is 100% by mass. 0.05 to 10% by mass, particularly 0.05 to 8% by mass, and more preferably 0.05 to 6% by mass. When the Ti content is 0.05 to 10% by mass, a bonding portion having practically sufficient strength can be formed even if the bonding atmosphere is an atmosphere having a low oxygen partial pressure.

The thermal expansion coefficient of the Ni-based brazing material is (11-14) × 10 ⁻⁶ / ° C., although it depends on the composition. On the other hand, the thermal expansion coefficient of the Ag-based brazing material is usually (16 to 20) × 10 ⁻⁶ / ° C. Furthermore, the thermal expansion coefficient of stainless steel, which is often used as various separators, is (12 to 17) × 10 ⁻⁶ / ° C., and the thermal expansion of ceramics such as ZrO ₂ -based and CeO ₂ -based materials that become solid electrolyte layers The rate is (10 to 11.5) × 10 ⁻⁶ / ° C. Thus, the difference between the thermal expansion coefficient of the Ni-based brazing material and the thermal expansion coefficient of each of the stainless steel and the ceramic is that the thermal expansion coefficient of the Ag-based brazing material and each of the thermal expansion coefficients of the stainless steel and the ceramic are Less than the difference. Therefore, when the Ni-based brazing material is used, the thermal stress is more easily relaxed, and a better bonded state is maintained.

  The Ni-based brazing material and the Ag-based brazing material may contain other metals in addition to the above-described various metals as long as the bonding strength, gas sealability, and the like are not deteriorated. Examples of such metals include Sn, In, and Nb. These other metals are 10 parts by mass or less, particularly 0.1 to 10 parts by mass, and further 0.5 to 5 parts by mass, when each of the Ni-based brazing material and the Ag-based brazing material is 100 parts by mass. It can be included.

  In the solid oxide fuel cell, it is not preferable that each cell be excessively thin or flat from the viewpoint of strength. Therefore, the solid electrolyte layer can be thickened to be a self-supporting type that increases the strength of the entire cell. On the other hand, it is not preferable to increase the thickness of the solid electrolyte layer from the viewpoint of power generation performance. In this case, the fuel electrode support type can be used, and in this fuel electrode support type, the fuel electrode is 20 times thicker than the solid electrolyte layer. It is preferable. If it is less than 20 times, the mechanical strength of the cell tends to decrease. In particular, when the fuel cell is a flat plate type, the thickness of the fuel electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, an air electrode support type can also be used as described below. In this case, the thickness of the fuel electrode is preferably 10 to 50 μm, particularly preferably 20 to 40 μm. If this thickness is 10 to 50 μm, it functions sufficiently as an electrode and does not need to be thicker than 50 μm.

  In a solid oxide fuel cell, the air electrode can also be formed as a substrate that supports the strength of the cell. Thus, when it is an air electrode support type, it is preferable that the thickness of an air electrode is 20 times or more the thickness of a solid electrolyte layer. If it is less than 20 times, the mechanical strength of the cell tends to decrease. In particular, when the fuel cell is a flat plate type, the thickness of the air electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, in the case of the fuel electrode support type, the thickness of the air electrode is preferably 10 to 100 μm, particularly preferably 20 to 50 μm. When the thickness is less than 10 μm, the electrode may not function sufficiently, and when the thickness exceeds 100 μm, the solid electrolyte layer may be peeled off.

[2] Method for Producing Solid Electrolyte Fuel Cell The method for producing the solid electrolyte fuel cell is not particularly limited. For example, the solid electrolyte fuel cell of the present invention, other of the present invention, and still another solid oxide fuel cell of the present invention is used. It can be manufactured by a manufacturing method.
(1) Manufacturing method of solid electrolyte fuel cell of this invention The manufacturing method of the solid electrolyte fuel cell of this invention is a lamination process which laminates | stacks a non-baking air electrode or a non-baking fuel electrode, and one side of a non-baking solid electrolyte layer. And a coating film forming step for forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral edge of the other surface of the unsintered solid electrolyte layer, and a non-sintered air electrode or the unsintered A simultaneous firing step in which the fuel electrode, the unfired solid electrolyte layer, and the metallized coating film are integrally fired, and the unfired fuel electrode or unfired air electrode on the other surface of the solid electrolyte layer 11 obtained by firing the unfired solid electrolyte layer. And then firing to produce the fuel electrode 12 or the air electrode 13 and the reducing metal oxide contained in the metallized layer 141 obtained by firing the metallized coating film. To generate metal The original process and the joining process which joins the metallization layer 141 and the isolation member 22 with a metal brazing material are provided in this order.

(A) Formation of unsintered fuel electrode or unsintered air electrode and unsintered solid electrolyte layer The method for forming the unsintered fuel electrode is not particularly limited. For example, a slurry containing a mixed powder of a metal oxide powder such as Ni and Fe and a ceramic powder such as a zirconia-based ceramic, various metal powders, and a mixed powder of a metal powder and a ceramic powder, a resin sheet, It is applied to the surface of a support material such as a rubber sheet and glass, then dried, and further heated as necessary. When the slurry contains an organic binder or the like, it is formed by removing the organic binder or the like. be able to. Further, the method for forming the unfired air electrode is not particularly limited. For example, a slurry containing various metal powders, metal oxide powders, metal double oxide powders, etc. is applied to the surface of a support material such as a resin sheet, rubber sheet and glass, and then dried, and further if necessary When the slurry contains an organic binder or the like, the slurry can be formed by removing the organic binder or the like. Furthermore, the method for forming the unfired solid electrolyte layer is not particularly limited. For example, a slurry containing ceramic powder that is a solid electrolyte is applied to the surface of a support material such as a resin sheet, a rubber sheet, and glass, then dried and further heated as necessary, and an organic binder or the like is added to the slurry. When contained, it can be formed by removing the organic binder and the like.

(B) Lamination process The method of laminating the unfired fuel electrode or unfired air electrode and one surface of the unfired solid electrolyte layer in the “lamination process” is not particularly limited. For example, in the self-supporting type, the above-described unfired fuel electrode slurry or unfired air electrode slurry is applied to the unfired solid electrolyte layer, then dried, and further laminated by heating as necessary. be able to. Furthermore, in the fuel electrode support type or the air electrode support type, the slurry for the unfired solid electrolyte is applied to the unfired fuel electrode or the unfired air electrode, then dried, and further heated as necessary. Can be laminated. In the self-supporting type, the unfired fuel electrode or unfired air electrode is formed in advance by using the above slurry to form a sheet that becomes the unfired fuel electrode or unfired air electrode, and this sheet is used as the unfired solid electrolyte layer. It can also be provided by stacking. Further, in the fuel electrode support type or the air electrode support type, the unsintered solid electrolyte layer forms a sheet that becomes the unsintered solid electrolyte layer in advance using the slurry, and this sheet is formed into the unsintered fuel electrode or unsintered body. It can also be provided by being laminated on the air electrode.

(C) Coating film formation process The method of forming a metallized coating film in the above "coating film formation process" is not particularly limited. For example, a slurry containing a reducing metal oxide powder such as NiO and a non-reducing metal oxide powder such as ZrO ₂ is applied to the peripheral edge of the other surface of the unfired solid electrolyte layer, and then dried. Furthermore, it can form by heating as needed. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, a squeegee method, and a spin coating method can be used.

(D) Co-firing step The "co-firing step" is a step of firing the unfired fuel electrode or unfired air electrode, the unfired solid electrolyte layer, and the metallized coating film integrally. The fuel electrode 12 or the air electrode 13, the solid electrolyte layer 11, and the metallized layer 141 are formed. Although the firing temperature of this co-firing depends on the type of raw material powder used, etc., when the above-mentioned various raw materials are used and the unfired fuel electrode is co-fired, it is 1250 to 1500 ° C., particularly 1250 to 1450 ° C. Furthermore, it is preferable to set it as 1300-1450 degreeC. If a calcination temperature is 1250-1500 degreeC, each unbaking body can fully be sintered. On the other hand, when the unfired air electrode is co-fired, it is preferably 800 to 1300 ° C, particularly preferably 800 to 1250 ° C, and more preferably 800 to 1200 ° C.
In addition, although it depends on the firing temperature, the time for maintaining the firing temperature can be 30 minutes to 5 hours, particularly 30 minutes to 3 hours. The firing atmosphere is usually an oxidizing atmosphere such as an air atmosphere.

(E) Fuel electrode or air electrode production process The method for forming an unfired fuel electrode or an unfired air electrode in the above "fuel electrode or air electrode production process" is as described in (A) above. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, a squeegee method, and a spin coating method can be used. The firing conditions for the unfired fuel electrode or the unfired air electrode are as described in (D) above. The unfired fuel electrode or unfired air electrode is preferably fired at a low temperature as much as possible. By firing at a lower temperature, the unfired body is already fired to form the fuel electrode 12. Alternatively, the air electrode 13 or the like is not excessively densified by the firing, and gas diffusion in the fuel electrode 12 and the air electrode 13 is not impaired.

(F) Reduction Step The “reduction step” is a step of reducing the reducible metal oxide contained in the metallized layer 141 to generate a metal, and the reduction method is a layer in which the metallized layer 141 improves the bondability. And the non-reducing metal oxide is not particularly limited and is not particularly limited. The reducing metal oxide can be reduced in an atmosphere having a temperature of 500 to 1000 ° C. and containing 0.01 to 7% by mass of hydrogen, with the balance being nitrogen or an inert gas. This temperature is preferably 550 to 950 ° C, particularly 600 to 850 ° C, and more preferably 650 to 750 ° C. Further, the hydrogen content in the reducing atmosphere is preferably 0.05 to 5% by mass, particularly 0.1 to 4% by mass, and more preferably 0.5 to 3% by mass. Furthermore, the temperature is preferably 550 to 950 ° C., and the hydrogen content is preferably 0.5 to 5% by mass, the temperature is 600 to 850 ° C., and the hydrogen content is 0.1 to 4%. It is more preferable that the mass is mass%, the temperature is 650 to 750 ° C., and the hydrogen content is particularly preferably 0.5 to 3 mass%.

(G) Joining Step The “joining step” is a step of joining the metallized layer 141 and the isolation member 22 together. The metallized layer 141 and the separating member 22 can be joined using the metal brazing material. The atmosphere during the bonding is not particularly limited as long as the atmosphere has a low oxygen partial pressure, and may be a vacuum atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like. When the metal brazing material is used, the bonding atmosphere is preferably an atmosphere having a low oxygen partial pressure. With such a bonding atmosphere, the bonding strength can be greatly improved. On the other hand, it is preferable that the oxygen partial pressure of the bonding atmosphere is low enough not to decompose the air electrode. The oxygen partial pressure in the atmosphere during bonding is not particularly limited, but is preferably 10 to 10 ⁻¹⁵ Pa, particularly preferably 10 to 10 ⁻¹⁰ Pa.

  The temperature at which the metallized layer 141 and the isolation member 22 are joined with the metal brazing material is not particularly limited, but the temperature is not lower than the solid phase temperature of the metal brazing material and not higher than the temperature exceeding the liquid phase temperature of 100 ° C. preferable. If the bonding is performed at a temperature equal to or higher than the solidus temperature of the metal brazing material, the metal brazing material is melted and sufficiently flows between the metallized layer 141 and the separating member 22 and can be brought into close contact with each other. In particular, when bonding is performed at a temperature exceeding the liquidus temperature of the metal brazing material, more stable and sufficient sealing properties and bonding strength are maintained, and they do not easily peel off.

Moreover, the atmosphere at the time of joining the metallized layer 141 and the isolation member 22 is not particularly limited as long as the atmosphere has a low oxygen partial pressure, and may be a vacuum atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like. When the metal brazing material is used, the bonding atmosphere is preferably an atmosphere having a low oxygen partial pressure. With such a bonding atmosphere, the bonding strength can be greatly improved. On the other hand, it is preferable that the oxygen partial pressure of the bonding atmosphere is low enough not to decompose the air electrode. The oxygen partial pressure in the atmosphere during bonding is not particularly limited, but is preferably 10 to 10 ⁻¹⁵ Pa, particularly preferably 10 to 10 ⁻¹⁰ Pa.

(2) Other Solid Electrolyte Fuel Cell Manufacturing Method of the Present Invention Another solid electrolyte fuel cell manufacturing method of the present invention is a solid electrolyte layer in which a solid electrolyte layer 11 is produced by firing an unfired solid electrolyte layer. A non-reduced metal oxide and a non-reducible metal oxide provided on the peripheral portion of the other side of the non-fired solid electrolyte layer by providing a non-fired air electrode or a non-fired fuel electrode on one surface of the solid electrolyte layer 11; An unsintered air electrode or an unsintered fuel electrode / metallized coating film forming step, a firing step of firing the unsintered air electrode or unsintered fuel electrode and the metallized coating film, and a solid electrolyte layer An unfired fuel electrode or an unfired air electrode is formed on the other surface of the fuel electrode 11 and then fired to produce a fuel electrode 12 or an air electrode 13, and a metallized coating film is fired. Contained in the metallized layer 141 A reducing step of reducing the reducing metal oxide to produce the metal, and a joining step of joining the metallized layer 141 and the separating member 22 with a metal brazing material in this order.

(A) Solid Electrolyte Layer Preparation Step In the “solid electrolyte layer preparation step”, the solid electrolyte layer 11 can be prepared by baking the unfired solid electrolyte layer.
The method for forming the unfired solid electrolyte layer is not particularly limited. For example, a slurry containing ceramic powder such as zirconia-based ceramic is applied to the surface of a support material such as a resin sheet, a rubber sheet and glass, then dried, and further heated as necessary to add an organic binder to the slurry. Can be formed by removing the organic binder and the like. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, a squeegee method, and a spin coating method can be used.

The firing temperature of the unsintered solid electrolyte layer depends on the type of raw material powder used, but when using the above-mentioned various raw materials, it may be set to 1250 to 1500 ° C., particularly 1250 to 1450 ° C., more preferably 1300 to 1450 ° C. preferable. When the firing temperature is 1250 to 1500 ° C., the unsintered solid electrolyte layer can be sufficiently sintered.
In addition, although it depends on the firing temperature, the time for maintaining the firing temperature can be 30 minutes to 5 hours, particularly 30 minutes to 3 hours. The firing atmosphere is usually an oxidizing atmosphere such as an air atmosphere.

(B) Unsintered fuel electrode or unsintered air electrode / metallized coating film forming step The unsintered fuel electrode or unsintered air electrode is formed in the “unsintered fuel electrode or unsintered air electrode / metallized coating film forming step”. The method is not particularly limited. The unsintered fuel electrode contains, for example, mixed powders of metal oxide powders such as Ni and Fe and ceramic powders such as zirconia ceramics, various metal powders, and mixed powders of metal powders and ceramic powders. The slurry is applied to one surface of the solid electrolyte layer 11, then dried, and further heated as necessary. When the slurry contains an organic binder or the like, the slurry is formed by removing the organic binder or the like. Can do. Further, the unsintered air electrode is prepared, for example, by applying a slurry containing various metal powders, metal oxide powders, metal double oxide powders, etc. to one surface of the solid electrolyte layer 11 and then drying it. When the organic binder etc. are contained in the slurry according to the heating, it can be formed by removing the organic binder. In any case, the coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, a squeegee method, and a spin coating method are exemplified.

Further, the method for forming the metallized coating film is not particularly limited. For example, a slurry containing a reducible metal oxide powder such as NiO and a non-reducible metal oxide powder such as ZrO ₂ is applied to the peripheral edge of the other surface of the solid electrolyte layer 11 and then dried. It can form by heating as needed and removing the organic binder etc. which are contained in a slurry. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, a squeegee method, and a spin coating method can be used.

(C) Firing step In the “firing step”, the unfired fuel electrode or unfired air electrode and the metallized coating film are integrally fired. Thereby, the fuel electrode 12 or the air electrode 13 and the metallized layer 141 are formed. The firing temperature depends on the type of raw material powder used, but when the above-mentioned various raw materials are used and the unfired fuel electrode is fired, it is 1250 to 1500 ° C., particularly 1250 to 1450 ° C., and further 1300 It is preferable to set it to -1450 degreeC. If a calcination temperature is 1250-1500 degreeC, each unbaking body can fully be sintered. Furthermore, when a non-baking air electrode is baked, it is preferable to set it as 800-1300 degreeC, especially 800-1250 degreeC, and also 800-1200 degreeC.
In addition, although it depends on the firing temperature, the time for maintaining the firing temperature can be 30 minutes to 5 hours, particularly 30 minutes to 3 hours. The firing atmosphere is usually an oxidizing atmosphere such as an air atmosphere.

(D) Fuel electrode or air electrode production process, reduction process, and joining process (E) Fuel electrode or air electrode production process, (F) Reduction process in the method for producing a solid electrolyte fuel cell of the present invention of (1) above, respectively. And (G) It is the same as that of a joining process.

(3) Still another method for producing a solid electrolyte fuel cell according to the present invention is a method for producing a solid electrolyte fuel cell according to another embodiment of the present invention. Other than the solid electrolyte layer 11 formed by firing the unfired solid electrolyte layer, the simultaneous firing step of integrally firing the unfired air electrode or unfired fuel electrode, and the unfired solid electrolyte layer Forming a metallized coating film containing a reducible metal oxide and a non-reducible metal oxide on the peripheral edge of the surface, and then firing to form a metallized layer 141; A reducing electrode contained in the metallized layer 141, and a fuel electrode or air electrode manufacturing step of forming a non-fired fuel electrode or a non-fired air electrode on the other surface and then firing to form the fuel electrode 12 or the air electrode 13. Reduce oxide to gold A reduction step for generating a reduced metal oxide and a joining step for joining the metallized layer 141 and the isolation member 22 with a metal brazing material are provided in this order.

In the above production method, the description of each step in the method for producing a solid electrolyte fuel cell of the present invention can be applied as it is to the lamination step, the reduction step, the joining step, and the fuel electrode or air electrode production step. The co-firing step is the co-firing in the method for producing a solid oxide fuel cell of the present invention except that a metallized coating film is not formed in the method for producing a solid electrolyte fuel cell of the present invention. The description regarding the process can be applied as it is. Furthermore, the metallized layer forming step is a step of forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral edge of the other surface of the solid electrolyte layer, and firing the metalized coating film. It is.
In the method for producing a solid electrolyte fuel cell, the solid electrolyte layer, the fuel electrode, the material used for forming the air electrode, the reducing metal oxide, the non-reducing metal oxide, etc. The description of the fuel cell can be applied as it is. The description of the solid oxide fuel cell can be applied as it is to various separators and metal brazing materials.

Hereinafter, the present invention will be described in detail by way of examples relating to flat plate cells and fuel cells.
[1] Evaluation of adhesion of metallized layer Examples 1 to 5, Comparative Examples 1 to 3 and Reference Examples 1 to 5
(1) Manufacture of solid oxide fuel cell (test cell) (a) Self-supporting type (Examples 1 to 3, Comparative Examples 1 to 3 and Reference Examples 1 to 3)
The unsintered solid electrolyte layer is a slurry in which 8 mol% of yttria is dissolved in zirconia (hereinafter referred to as “8YSZ”) powder, a mixed solvent of toluene and methyl ethyl ketone as a solvent, and polyvinyl alcohol as a binder. And prepared by the doctor blade method. The unburned fuel electrode is a mixture of nickel oxide (NiO) powder and the above 8YSZ powder, and then blended artificial graphite powder as a pore former, further mixed, and then butyl carbitol as a solvent. Using the blended slurry, a screen printing method was used.

Furthermore, the unsintered air electrode was produced by a screen printing method using a slurry in which butyl carbitol was blended as a solvent with La _0.6 Sr _0.4 MnO ₃ powder. In addition, the metallized coating film used as the metallized layer is a reducible metal oxide powder [NiO powder (metal Ni is generated by reduction) or a mixed powder of NiO and Co ₃ O ₄ (metal by reduction). Ni and metal Co are formed.)] In a mixed powder of 50% by mass and non-reducible metal oxide (mixed ceramic, 8YSZ or Y ₂ O ₃ ) 50% by mass, butyl carbitol is added as a solvent. Using the blended slurry, a screen printing method was used.

(B) Fuel electrode support type (Examples 4 and 5 and Reference Examples 4 and 5)
The non-fired fuel electrode is a mixture of nickel oxide (NiO) powder and the above 8YSZ powder, then blended artificial graphite powder as a pore former, further mixed, then diethylamine as a dispersant, and organic solvent Toluene and methyl ethyl ketone were blended, and then dibutyl phthalate was blended as a plasticizer, polyvinyl alcohol was blended as a binder, and a slurry prepared by further mixing was prepared by a doctor blade method. The unsintered solid electrolyte layer is produced by screen printing using a slurry in which butyl carbitol is mixed as a solvent in a zirconia (hereinafter referred to as “8YSZ”) powder in which 8 mol% of yttria is dissolved. did.
Furthermore, the unsintered air electrode and the metallized coating film were prepared by the same method using the same slurry as in the case of the self-supporting type.

  The above-mentioned ones were used as the green bodies, and solid oxide fuel cells were produced according to the production procedures (1) to (4) shown in Table 1. The solid electrolyte layer of this cell is 50 × 50 mm in size, and the thickness is 300 μm for the self-supporting type and 20 μm for the fuel electrode support type. The fuel electrode is 35 × 35 mm for the self-supporting type, 50 × 50 mm for the fuel electrode supporting type, and has a thickness of 30 μm for the self-supporting type and 1300 μm for the fuel electrode supporting type. Further, the air electrode has a size of 35 × 35 mm, and the thickness is 30 μm in both of the self-supporting type and the fuel electrode supporting type. The metallized layer formed on the peripheral edge of the solid electrolyte layer has a width of 5 mm and a thickness of 5 μm.

尚、表１及び表２における「８ＹＳＺ」は、８モル％のイットリアが固溶されたジルコニアである。また、「ＬＳＭ」は、Ｌａ_０．６Ｓｒ_０．４ＭｎＯ_３である。

In Tables 1 and 2, “8YSZ” is zirconia in which 8 mol% of yttria is dissolved. “LSM” is La _0.6 Sr _0.4 MnO ₃ .

(2) Peeling test Using the test body prepared in the above (1), a cloth adhesive tape was stuck on the entire surface of the metallized layer, and then a peeling test using the adhesive tape was performed by peeling. The residual rate was calculated as follows. The results are also shown in Table 2.
Residual rate (%) = [(area of metallized layer before test−area of metallized layer after test) / area of metallized layer before test] × 100
In Reference Examples 1 to 5, it is not reduced and remains a metal oxide, so it does not have a metallizing function but is referred to as a metallized layer for convenience.

According to the results of Table 2, in Examples 1 to 5, the residual rate after the peel test, regardless of the type of the reducing metal oxide and the non-reducing metal oxide used for forming the cell and forming the metallized layer Is 100%, and it can be seen that the metallized layer is sufficiently adhered to the solid electrolyte layer. On the other hand, in Comparative Example 1 in which a metallized layer was formed by baking Ni under a nitrogen atmosphere at 1200 ° C. for 1 hour on the periphery of the solid electrolyte layer, the residual rate was extremely low at 20%, which was inferior. Further, in Comparative Example 2 in which an electroless Ni plating layer was formed on the periphery of the solid electrolyte layer by a conventional method as a metallized layer, the residual rate was 100%, which was excellent. A part of the pole was dissolved. Furthermore, in Comparative Example 3 in which the Mo-Mn metallized layer was formed on the peripheral edge of the solid electrolyte layer by a conventional method as a metallized layer, the residual rate was 95%, which was sufficient. The presence of a constituent phase produced by oxygen deficiency such as Sr ₂ Co ₂ O ₅ was confirmed by X-ray diffraction.
In Reference Examples 1 to 5, it can be seen that the residual ratio after the peel test is 100%, and the metallized layer is sufficiently adhered to the solid electrolyte layer.

[2] Bond strength between the solid electrolyte layer of the solid oxide fuel cell and the metal separator, and the power generation performance of the cells Examples 6 to 15 and Comparative Examples 5 to 6
(1) Manufacture of solid electrolyte fuel cell (test cell) A mixed solvent of toluene and methyl ethyl ketone as a solvent and polyvinyl alcohol as a binder are mixed with zirconia powder stabilized by 10 mol% of scandia, A slurry for a fired solid electrolyte layer was prepared. Then, this slurry was apply | coated to one surface of the resin sheet by the doctor blade method, and the unbaking solid electrolyte layer was formed. Next, nickel oxide (NiO) powder and 8YSZ powder were mixed, and then artificial graphite powder was blended as a pore former and further mixed. Next, butyl carbitol was blended as a solvent to prepare an unfired fuel electrode slurry. Thereafter, using this slurry, an unfired fuel electrode was formed concentrically with the unfired solid electrolyte layer on one surface of the unfired solid electrolyte layer by screen printing.

  Thereafter, 80% by volume of the metallized material (reducible metal oxide) described in Tables 3 and 4 and 20% by volume of mixed ceramics (non-reducible metal oxide) were mixed, and then butyl carbitol was used as a solvent. Mixing was performed to prepare a slurry for a metallized coating film. Then, using this slurry, a metallized coating film was formed concentrically with the unfired solid electrolyte layer on the edge of the other surface of the unfired solid electrolyte layer by screen printing. Subsequently, it baked integrally by hold | maintaining at 1400 degreeC in an air atmosphere for 1 hour. After firing, the solid electrolyte layer 11 had a diameter of 20 mm and a thickness of 500 μm, the fuel electrode 12 had a diameter of 10 mm and a thickness of 15 μm, and the metallized layer 141 had an outer diameter of 20 mm, an inner diameter of 12 mm, and a thickness of 15 μm.

Thereafter, a slurry was prepared by mixing butyl carbitol as a solvent with La _0.6 Sr _0.4 (Co _0.2 Fe _0.8 ) O ₃ powder. Next, using this slurry, an unfired air electrode was formed concentrically with the solid electrolyte layer 11 on the other surface of the solid electrolyte layer 11 by screen printing. Then, it hold | maintained at 1100 degreeC for 1 hour, and baked, and formed the air electrode 13 10 mm in diameter and 15 micrometers in thickness. Thereafter, the metallized material (reducible metal oxide) is reduced by heating to 700 ° C. in a reducing atmosphere composed of 2% by mass of hydrogen and 98% by mass of nitrogen to form Ni or Co, and the metallized layer 141 is formed. The test cell was manufactured.

(2) Joining of Test Cell Separator Test Cell Separator 81 Composed of Metallized Layer 141 Formed at the Edge of Other Surface of Solid Electrolyte Layer 12 of Test Cell Produced in (1) above and SUS430 The solid oxide fuel cell 102 is a metal separator corresponding to the separators 221, 222, and 223, has an outer diameter of 40 mm, a thickness of 50 μm, and an opening having a diameter of 12 mm in the center. A bonding layer 14 was formed by brazing at 1100 ° C. in a vacuum atmosphere using a metal brazing material described in Table 3 between the inner peripheral edge and the inner peripheral edge.

尚、表３及び表４における「８ＹＳＺ」は、８モル％のイットリアが固溶され、安定化されたジルコニアである。また、「ＳｃＳＺ」は、１０モル％のスカンジアが固溶され、安定化されたジルコニアである。

“8YSZ” in Tables 3 and 4 is zirconia stabilized by dissolving 8 mol% of yttria. “ScSZ” is zirconia stabilized by dissolving 10 mol% of scandia.

(3) Electron microscope observation of the bonding interface The bonding layer formed by brazing in (2) above is fixed with resin including the peripheral members, then cut in the direction of the metal separator and the fuel electrode, The sample was mirror-polished and observed with an electron microscope. As a result, the metal brazing material was integrated with the test cell separator 81 and the metallized layer 141 such that the respective bonding interfaces could not be confirmed. It was also confirmed that the mixed ceramics (non-reducing metal oxide) contained in the metallized layer 141 and the ScSZ constituting the solid electrolyte layer 11 were co-sintered at the bonding interface. Thus, it was found that the solid electrolyte layer 11 and the test cell separator 81 were firmly joined.

(4) Measurement of bonding strength Five test cells, each of Examples 6 to 18 and Comparative Examples 5 to 6, were prepared and bonded to each other at 25 ° C. Heat up to ˜800 ° C. at a rate of 12 ° C./min, hold at 800 ° C. for 1 hour, and then add 1, 3, 5 and 10 heat cycles to cool down to 25 ° C. at a rate of 12 ° C./min, The effect of thermal cycle on bonding strength was investigated. In addition, five test bodies were produced and evaluated for each of Examples 6 to 18 and Comparative Examples 5 to 6 for each number of thermal cycles.

  As shown in FIG. 11, the test cell separator 81 produced in (2) above was joined to the upper surface of a cylindrical support base 82 made of SUS430 having an outer diameter of 40 mm, an inner diameter of 22 mm, and a height of 3 mm. The test cell is placed so that the outer periphery of the support base 82 and the outer periphery of the test cell separator 81 coincide with each other. Thereafter, the load cell is made of SUS430 having a diameter of 10 mm and a height of 10 mm on the upper surface of the air electrode 13. Next, a load is applied from above the load loading jig 83, the load when the test cell separator 81 and the solid electrolyte layer 11 are peeled off is measured, and this load is divided by the bonding area. Calculated. The results are also shown in Tables 3 and 4 as average values of 5 test specimens.

(5) Evaluation of power generation performance As shown in FIG. 12, the upper and lower surfaces of the outer peripheral edge of the test cell separator 81 of the test cell prepared in (2) above are placed outside through an alumina tube seal portion 85 made of seal glass. It was sandwiched between alumina tubes 841. Thereafter, platinum nets 861 attached to the respective tips of the upper and lower inner alumina tubes 842 were brought into contact with the fuel electrode 12 and the air electrode 13, respectively. Next, this test apparatus is housed in an electric furnace adjusted to 700 ° C., hydrogen gas is circulated in the lower inner alumina tube 842, and oxygen gas mixed in the upper inner alumina tube 842 at the same ratio as the atmosphere. A mixed gas of nitrogen and nitrogen gas was circulated to generate electric power, and electricity was taken out from a platinum wire 862 connected to a platinum net 861 to obtain a power generation output. This test cell can be operated at a lower temperature because LSCF or the like is used for the air electrode. Therefore, the power generation performance was evaluated at 700 ° C. The results are also shown in Tables 3 and 4.

According to the results of Tables 3 and 4, in Examples 6 to 18, the bonding strength after one thermal cycle is 482 to 498 kPa / mm ² , and the bonding strength after 10 thermal cycles is 482 to 490 kPa / mm ² . Thus, it can be seen that there is almost no decrease in bonding strength due to thermal cycling regardless of the type of metallized material (reducing metal oxide), mixed ceramics (non-reducing metal oxide) and metal brazing material. Furthermore, in the case of Examples 6 to 9 where NiO is used as the metallizing material and 8YSZ is used as the mixed ceramic and the content of 8YSZ is changed to 5 to 30% by mass, there is almost no decrease in the bonding strength due to the thermal cycle. It was. On the other hand, in Comparative Example 5 in which the solid electrolyte layer 11 and the test separator were directly bonded without using a metallized layer, the bonding strength at one thermal cycle was as extremely low as 51 kPa / mm ^2, and the thermal cycle was applied ten times. The solid electrolyte layer 11 and the test separator were peeled off by this thermal cycle. Further, in Comparative Example 6 in which the solid electrolyte layer 11 and the test separator were joined through a metallized layer formed by a normal Mo-Mn method, although the joining strength per thermal cycle was as high as 492 kPa / mm ² , It can be seen that the bonding strength after 10 cycles is greatly reduced to 397 kPa / mm ² .

Moreover, according to the evaluation of the power generation performance using the test bodies of Examples 6 to 12 and 16 to 18 and Comparative Examples 5 to 6, the solid electrolyte layer 11 and the test separator were directly joined without using the metallized layer. Based on the power generation output of 0.33 W / cm ² in Example 5, the deterioration rate expressed as a percentage with respect to this reference value is 0 to 6% at the maximum in Examples 6 to 12 and 16 to 18, and the deterioration rate is It can be seen that it is extremely small. On the other hand, in Comparative Example 6 in which the metallized layer was formed by the usual Mo—Mn method, the power generation output was 0.07 W / cm ² , the deterioration rate was 79%, and it can be seen that the power generation performance was greatly reduced.

[3] Solid electrolyte fuel cell Example 16
The fuel electrode support type solid electrolyte fuel cell of the present invention was used, and a fuel electrode support type internal manifold type solid oxide fuel cell having three cells was manufactured.
(1) Structure of fuel cell (a) Cells and various separators The appearance of a flat plate type fuel cell 1021 having a structure in which three cells are stacked is shown in a perspective view in FIG. 4 is a schematic diagram of the AA cross section in FIG. 3, and FIG. 5 is a schematic diagram of the BB cross section in FIG.
In this flat plate type fuel cell 1021, three cells 101 are stacked via interconnectors 211 and 212. Each cell uses a fuel electrode 12 having a square planar shape as a substrate. On the surface of the fuel electrode 12, a solid electrolyte layer 11 having the same shape and size in the planar direction as the fuel electrode 12 is formed. Further, on the surface of the solid electrolyte layer 11, an air electrode 13 having the same shape in the planar direction as the solid electrolyte layer 11 and having a size smaller than that of the solid electrolyte layer 11 is formed.

The upper cell includes a nickel felt layer 31 disposed on the upper surface of the interconnector 211, a fuel electrode 12 serving as a substrate, a solid electrolyte layer 11, an air electrode 13, an Inconel fiber mesh layer 32, and a lid member 23 in this order. Further, the lower surface is joined to the solid electrolyte layer 11 and the metal frame body 62, and the upper surface is interposed through the ceramic frame body 51 and the metal frame body 61 made of an MgO—MgAl ₂ O ₄ sintered body that is an insulating ceramic. An upper cell isolation separator 221 joined to the lid member 23 is provided.
The intermediate cell includes a nickel felt layer 31 disposed on the upper surface of the interconnector 212, a fuel electrode 12 serving as a substrate, a solid electrolyte layer 11, an air electrode 13, and an Inconel fiber mesh layer 32 in this order. Further, the lower surface is joined to the solid electrolyte layer 11 and the metal frame 64, and the upper surface is interposed through the ceramic frame 52 and the metal frame 63 made of an MgO—MgAl ₂ O ₄ sintered body that is an insulating ceramic. An intermediate cell isolation separator 222 joined to the interconnector 211 is provided.
The lower cell includes a nickel felt layer 31 disposed on the upper surface of the bottom member 24, a fuel electrode 12 serving as a substrate, a solid electrolyte layer 11, an air electrode 13, and an Inconel fiber mesh layer 32 in this order. The lower cell isolation separator 223 has a lower surface bonded to the solid electrolyte layer 11 and the metal frame 66 and an upper surface bonded to the interconnector 212 via the ceramic frame 53 and the metal frame 65. .

  Lid member 23, upper cell isolation separator 221, intermediate cell isolation separator 222, lower cell isolation separator 223, interconnectors 211 and 212, metal frames 61, 62, 63, 64, 65, 66 and bottom member 24 Are both formed of SUS430. Furthermore, the lid member 23 and the metal frame 61, the upper cell isolation separator 221 and the metal frame 62, the metal frame 62 and the interconnector 211, the interconnector 211 and the metal frame 63, and the intermediate cell isolation separator 222 and metal frame 64, metal frame 64 and interconnector 212, interconnector 212 and metal frame 65, lower cell isolation separator 223 and metal frame 66, and metal frame 66 and bottom member 24, each using a Ni-based metal brazing material, and joined at 1100 ° C. in a vacuum atmosphere to form a joint 4. Further, the metal frame 61 and the upper cell isolation separator 221, the metal frame 63 and the intermediate cell isolation separator 222, and the metal frame 65 and the lower cell isolation separator 223 are the ceramic frame 51, respectively. Similarly, a Ni-based metal brazing material is used and bonded at 1100 ° C. in a vacuum atmosphere to form a bonded portion 4.

(B) Fuel gas introduction pipe or discharge pipe, and combustion-supporting gas introduction pipe or discharge pipe In the upper cell, the space formed between the upper cell isolation separator 221 and the interconnector 211 has no fuel in the upper cell. A fuel gas introduction pipe 71 for introducing fuel gas into the pole 12 is opened (see FIG. 4). Furthermore, a fuel gas discharge pipe 72 for discharging fuel gas from the fuel electrode 12 of the upper cell is opened on the diagonal side of the opening of the fuel gas introduction pipe 71 in this space (see FIG. 4). In addition, in the space formed between the lid member 23 and the upper cell isolation separator 221, a support gas introducing pipe 73 for introducing the support gas into the air electrode 13 of the upper cell is opened. (See FIG. 5). Further, on the diagonal side of the opening of the combustion-supporting gas introduction pipe 73 in this space, a combustion-supporting gas discharge pipe 74 for discharging combustion-supporting gas from the air electrode 13 of the upper cell is opened ( (See FIG. 5).

  Further, in the intermediate cell, a fuel gas introduction pipe 71 for introducing fuel gas into the fuel electrode 12 of the intermediate cell is opened in a space formed between the intermediate cell isolation separator 222 and the interconnector 212. (See FIG. 4). Furthermore, a fuel gas discharge pipe 72 for discharging fuel gas from the fuel electrode 12 of the upper cell is opened on the diagonal side of the opening of the fuel gas introduction pipe 71 in this space (see FIG. 4). In addition, in the space formed between the interconnector 211 and the intermediate cell isolation separator 222, a support gas introducing pipe 73 for introducing the support gas into the air electrode 13 of the intermediate cell is opened. (See FIG. 5). Further, on the diagonal side of the opening of the combustion-supporting gas introduction pipe 73 in this space, a combustion-supporting gas discharge pipe 74 for discharging combustion-supporting gas from the air electrode 13 of the upper cell is opened ( (See FIG. 5).

Further, in the lower cell, a fuel gas introduction pipe 71 for introducing fuel gas into the fuel electrode 12 of the lower cell is opened in a space formed between the lower cell isolation separator 223 and the bottom member 24. (See FIG. 4). A fuel gas discharge pipe 72 for discharging fuel gas from the fuel electrode 12 of the lower cell is opened on the diagonal side of the opening of the fuel gas introduction pipe 71 in this space (see FIG. 4). Further, in the space formed between the interconnector 212 and the lower cell isolation separator 223, a support gas introducing pipe 73 for introducing the support gas into the air electrode 13 of the lower cell is opened. (See FIG. 5). Further, on the diagonal line side of the opening of the combustion-supporting gas introduction pipe 73 in this space, a combustion-supporting gas discharge pipe 74 for discharging combustion-supporting gas from the air electrode 13 of the lower cell is opened ( (See FIG. 5).
In the fuel cell of Example 16, when another cell is stacked on the upper surface of the upper cell, the lid member functions as an interconnector. Furthermore, when another cell is further laminated on the lower surface of the lower cell, the bottom member functions as an interconnector.

  Each pipe for introducing or discharging fuel gas or combustion-supporting gas into each of the upper cell, intermediate cell and lower cell has a structure in which a side pipe is attached to the main pipe, Fuel gas or combustion-supporting gas is simultaneously introduced into and discharged from the intermediate cell and the lower cell. Further, in the case of the sixteenth embodiment, the fuel gas introduction pipe and the fuel gas discharge pipe, and the fuel support gas introduction pipe and the combustion support gas discharge pipe are respectively circulated in the diagonal direction. It is attached to such a position. Thereby, each fuel electrode and fuel gas of an upper cell, an intermediate | middle cell, and a lower cell and an air electrode and a combustion-supporting gas can be made to contact each efficiently.

(2) Extraction of Power from Fuel Cell In this fuel cell 1021, the fuel electrode 12 of the upper cell is electrically connected to the interconnector 211 via the nickel felt layer 31. Further, the interconnector 211 is electrically connected to the air electrode 13 of the intermediate cell via the Inconel fiber mesh layer 32. Further, the fuel electrode 12 of the intermediate cell is electrically connected to the interconnector 212 via the nickel felt layer 31. The interconnector 212 is electrically connected to the air electrode 13 of the lower cell via the Inconel fiber mesh layer 32. Thus, the upper cell, the intermediate cell, and the lower cell are connected in series. Further, the stack is heated to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe 71 and brought into contact with the fuel electrode 12, and a combustion-supporting gas such as air is introduced into the combustion-supporting gas introduction pipe 73. Is introduced and brought into contact with the air electrode 13, an electromotive force is generated between the fuel electrode 12 and the air electrode 13, and the electric power can be taken out to function as a power generator. The electric power is taken out to the bottom member 24 on the fuel electrode side and taken out to the lid member 23 on the air electrode side, and the electric power of the entire stack can be taken out between the lid member 23 and the bottom member 24.

(3) Operation of the fuel cell In this solid electrolyte fuel cell, each of the three cells is a fuel electrode support type. With this structure, current can be taken out even at an operating temperature of about 750 ° C. Therefore, the lid member, various separators, the metal frame, and the bottom member can be formed of stainless steel such as SUS430 instead of ceramic. In each of the upper cell, the intermediate cell, and the lower cell, the metallized layer provided in the solid electrolyte layer and the isolation separator are bonded at 1100 ° C. in a vacuum atmosphere using a metal brazing material to form a bonding layer 14. ing.

  When power is generated using the solid oxide fuel cell of Example 16, fuel gas is introduced to the fuel electrode side, and combustion-supporting gas is introduced to the air electrode side. As fuel gas, hydrogen, hydrocarbon as a hydrogen source, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and fuel obtained by mixing these gases with water vapor Gas etc. are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. Further, the main components are saturated hydrocarbons having 1 to 10, preferably 1 to 7, more preferably 1 to 4 carbon atoms such as methane, ethane, propane, butane and pentane, and unsaturated hydrocarbons such as ethylene and propylene. Those having a saturated hydrocarbon as a main component are more preferable. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the combustion-supporting gas include a mixed gas of oxygen and another gas. The mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Among these combustion-supporting gases, air (containing about 80% by volume of nitrogen) is preferable because it is safe and inexpensive.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention depending on the purpose, application, and the like. For example, the planar shape of the cell can be a rectangle, a circle, an ellipse, or the like, and a solid oxide fuel cell having a similar planar shape can be obtained.

It is a schematic diagram which shows the cross section of an example (flat plate type) of the solid oxide fuel cell 1011 of this invention. It is a schematic diagram which shows a part of cross section of the joined body which joined the isolation separator to the solid electrolyte layer of the solid oxide fuel cell of FIG. FIG. 16 is a perspective view showing a flat solid electrolyte fuel cell 102 of Example 16. It is a schematic diagram which shows the AA cross section of the solid oxide fuel cell 102 of FIG. FIG. 4 is a schematic diagram showing a BB cross section of the solid oxide fuel cell 102 of FIG. 3. It is a schematic diagram which shows the cross section (interconnector is arrange | positioned) of the other example (flat cylindrical cell 1012) of the solid oxide fuel cell of this invention. FIG. 7 is a perspective view showing a state in which four solid oxide fuel cells 1012 of FIG. 6 are connected via an interconnector, and a fuel gas introduction / separation member is disposed at the bottom. FIG. 8 is a schematic diagram showing a state in which the metallized layer provided at the peripheral edge of the solid electrolyte layer and the fuel gas introduction / separation member in FIG. 7 are joined by brazing. It is a schematic diagram which shows the cross section (The interconnector is arrange | positioned.) Of the other example (cylindrical cell 1013) of the solid oxide fuel cell of this invention. It is a perspective view of a test cell and a metal separator. It is a schematic diagram which shows the cross section of the test body which measures joining strength. The downward arrow at the top of the load loading jig represents the load. It is a schematic diagram which shows the cross section of the test body which measures electric power generation performance.

Explanation of symbols

  1011, 1012, 1013; solid electrolyte fuel cell, 102; solid electrolyte fuel cell, 11; solid electrolyte layer, 12; fuel electrode, 13; air electrode, 14; bonding layer, 141; metallized layer, 1411; Oxide (non-reducible metal oxide), 142; brazing layer, 21; interconnector, 211, 212, 213, 214; interconnector, 22; isolation member, 221; isolation separator for upper cell, 222; intermediate cell Separator for separator, 223; Separator for lower cell, 224; Fuel gas introduction and isolation member, 23; Lid member, 24; Bottom member, 31; Nickel felt layer, 32; Inconel fiber mesh layer, 4; 52, 53; Ceramic frame, 61, 62, 63, 64, 65, 66; Metal frame, 71; Fuel gas introduction pipe, 72 Fuel gas exhaust pipe, 73; Supporting gas introduction pipe, 74; Supporting gas exhaust pipe, 81; Test battery separator, 82; Support base, 83; Load load jig, 841; Outer alumina pipe, 842; inner alumina tube, 85; seal portion for alumina tube, 861; platinum net, 862; platinum wire.

Claims (10)

A solid electrolyte layer 11, a fuel electrode 12 provided on one surface of the solid electrolyte layer 11, an air electrode 13 provided on the other surface of the solid electrolyte layer 11, and the one surface or the other of the solid electrolyte layer 11. In a solid oxide fuel cell comprising: a metallized layer 141 provided on the peripheral edge of the surface;
The metallized layer 141 is made of a mixture of a metal and a metal oxide, and is a solid oxide fuel cell.   The solid oxide fuel cell according to claim 1, wherein the metal is at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. 3. The solid electrolyte fuel according to claim 1, wherein the solid electrolyte layer 11 is made of a ZrO ₂ -based ceramic, and the metal oxide is at least one of ZrO ₂ , MgO, CaO, and a rare earth element oxide. Battery cell.   The solid according to any one of claims 1 to 3, wherein the metal is 60 to 99 mass% and the metal oxide is 1 to 40 mass% when the mixture is 100 mass%. Electrolyte fuel cell. A solid oxide fuel cell comprising a structure in which the solid electrolyte fuel cell according to any one of claims 1 to 4 is connected via an interconnector 21;
Each of the solid electrolyte fuel cells is partially joined to the solid electrolyte layer 11 and introduces a combustion-supporting gas into the air electrode 13 and a flow path for introducing fuel gas into the fuel electrode 12. Characterized in that the metallized layer 141 provided on each solid electrolyte layer 11 and the isolation member 22 are joined by a metal brazing material, respectively. Solid electrolyte fuel cell. A method for producing a solid oxide fuel cell according to claim 5,
A laminating step of laminating the unsintered air electrode or unsintered fuel electrode and one surface of the unsintered solid electrolyte layer;
A coating film forming step of forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral edge of the other surface of the unfired solid electrolyte layer;
A co-firing step of integrally firing the unfired air electrode or the unburned fuel electrode, the unfired solid electrolyte layer, and the metallized coating;
A fuel electrode or a non-sintered air electrode formed on the other surface of the solid electrolyte layer 11 formed by firing the unsintered solid electrolyte layer, and then fired to produce the fuel electrode 12 or the air electrode 13 Air electrode manufacturing process;
A reduction step of reducing the reducing metal oxide contained in the metallized layer 141 obtained by firing the metallized coating film to produce the metal;
A method of manufacturing a solid oxide fuel cell, comprising: a joining step of joining the metallized layer 141 and the isolation member 22 with a metal brazing material in this order. A method for producing a solid oxide fuel cell according to claim 5,
A solid electrolyte layer manufacturing step of baking the unfired solid electrolyte layer to form the solid electrolyte layer 11, an unburned air electrode or an unburned fuel electrode provided on one surface of the solid electrolyte layer 11, and the unburned solid electrolyte layer A non-fired air electrode or a non-fired fuel electrode / metallized coating film forming step for forming a metallized coating film containing a reducing metal oxide and a non-reducing metal oxide on the peripheral portion of the other surface;
A firing step of firing the unfired air electrode or the unfired fuel electrode and the metallized coating;
A fuel electrode or air electrode manufacturing step of forming a non-fired fuel electrode or a non-fired air electrode on the other surface of the solid electrolyte layer 11, and then firing to produce the fuel electrode 12 or the air electrode 13;
A reduction step of reducing the reducing metal oxide contained in the metallized layer 141 obtained by firing the metallized coating film to produce the metal;
A method of manufacturing a solid oxide fuel cell, comprising: a joining step of joining the metallized layer 141 and the isolation member 22 with a metal brazing material in this order. A method for producing a solid oxide fuel cell according to claim 5,
A laminating step of laminating the unsintered air electrode or unsintered fuel electrode and one surface of the unsintered solid electrolyte layer;
A co-firing step of integrally firing the unfired air electrode or the unburned fuel electrode and the unfired solid electrolyte layer;
A metallized coating film containing a reducing metal oxide and a non-reducing metal oxide is formed on the periphery of the other surface of the solid electrolyte layer 11 formed by firing the unfired solid electrolyte layer, and then fired. A metallization layer forming step of forming the metallization layer 141;
A fuel electrode or air electrode manufacturing step of forming a non-fired fuel electrode or a non-fired air electrode on the other surface of the solid electrolyte layer 11, and then firing to produce the fuel electrode 12 or the air electrode 13;
A reduction step of reducing the reducible metal oxide contained in the metallized layer 141 to produce a reduced metal oxide,
A method of manufacturing a solid oxide fuel cell, comprising: a joining step of joining the metallized layer 141 and the isolation member 22 with a metal brazing material in this order.   The reducing metal oxide contains at least one metal element selected from Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. A method for producing a solid oxide fuel cell according to Item.   The said reduction | restoration process is 500-1000 degreeC, and contains 0.01-7 mass% hydrogen, and is any one of the Claims 6 thru | or 9 made in the reducing atmosphere which remainder is nitrogen or an inert gas. A method for producing a solid oxide fuel cell as described in 1).

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