JP2006172989A - 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 having a metallized layer provided by a method which does not produce the performance deterioration of a member, such as an air pole, etc., in a solid electrolyte layer, and to provide a solid electrolyte fuel battery which has a high heat resistance by brazing the metallized layer and an inter-connector and which can form a connector having a sufficient bonding strength and its manufacturing method. <P>SOLUTION: This solid electrolyte fuel battery includes, in the solid electrolyte fuel battery cell, a solid electrolyte layer 11, a fuel pole 12 provided in the one surface of the solid electrolyte layer 11, an air pole 13 which the solid electrolyte layer 11 is provided on the other hand, and is prepared, a metallized layer 141 provided in the peripheral edge of one or other surface of the solid electrolyte layer 11, the metallized layer 141 is made of the reductant of a metal oxide. This metallized layer 141 can be provided by a method which does not perform the performance deterioration of the member, such as the air pole, etc. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a solid oxide fuel cell having good bonding properties of a bonding layer with a separating member such as a metal separator that separates each gas, 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 fuel cell having a metallized layer provided by a method that does not cause a decrease in performance of a member such as an air electrode at the periphery of the solid electrolyte layer, and the metallized layer By brazing the metal isolation member, it is possible to form a bonding layer having high heat resistance and sufficient bonding strength, whereby the flow path of the fuel gas and the flow path of the combustion-supporting gas The present invention relates to a solid oxide fuel cell in which is isolated, and a method for manufacturing the same.
The present invention can be widely used in solid oxide fuel cells having various structures.

  A solid electrolyte fuel cell (hereinafter sometimes referred to as a “fuel cell”) is formed by stacking a plurality of cells using a separating member. 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 flow path can be isolated by joining a flow path isolation member to the solid electrolyte layer.

  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 a metal isolation member and an interconnector instead of ceramic, and use an inexpensive stainless steel isolation member or the like to lower the cost. You can also. The joining of the separating member 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 separating 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 metallization methods, it is possible to form a heat-resistant bonding layer and to bond without decomposing the air electrode. It's 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.

Further, in the film formation by CVD, since the actual film formation amount with respect to the target to be used is small, it takes time to obtain the required thickness, and it cannot be said to be 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 a member such as an air electrode is eluted during acid treatment necessary for plating. 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 the other surface of the solid electrolyte layer 11, and the one surface or the other of the solid electrolyte layer 11. A solid oxide fuel cell comprising a metallized layer 141 provided on the peripheral edge of the surface, wherein the metallized layer 141 is made of a reduced metal oxide.
2. The reduction product is at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. The solid oxide fuel cell described in 1.
3. Above 1. Or 2. A solid oxide fuel cell having a structure in which the solid electrolyte fuel cells described in 1 are connected via an interconnector 21 (for example, 211, 212 in FIGS. 4 and 5), each of the solid electrolyte fuel cells The fuel battery cell is partially joined to the solid electrolyte layer 11 and has a flow path for introducing fuel gas into the fuel electrode 12 and a flow path for introducing combustion-supporting gas into the air electrode 13. A solid oxide fuel cell comprising an isolation member 22 for isolating the metallized layer 141, wherein the metallized layer 141 provided on each solid electrolyte layer 11 and the isolation member 22 are joined to each other by a metal brazing material. .
4). 3. above. A method for producing a solid electrolyte fuel cell according to claim 1, wherein a laminating step of laminating one side of an unsintered air electrode or an unsintered fuel electrode and an unsintered solid electrolyte layer, and the other side of the unsintered solid electrolyte layer A coating film forming step for forming a metallized coating film containing the above metal oxide on the peripheral portion, the unfired air electrode or the unfired fuel electrode, the unfired solid electrolyte layer, and the metallized coating film are integrally fired. A co-firing step, 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 to form a fuel electrode 12 or an air electrode 13. A fuel electrode or air electrode production step, a reduction step of reducing the metal oxide contained in the metallized layer 141 obtained by firing the metallized coating film to generate the reduced product, and the metallized layer 141 And the isolation member Joining step and a method for producing a solid electrolyte fuel cell characterized by comprising in this order 2 are bonded by a metal brazing material.
5. 3. 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. Alternatively, an unsintered air electrode or an unsintered fuel electrode / metallized coating film is formed on the peripheral surface of the other surface of the unsintered solid electrolyte layer. A firing step for firing the unfired air electrode or the unfired fuel electrode and the metallized coating film, and forming a unfired fuel electrode or an unfired air electrode on the other surface of the solid electrolyte layer 11; A fuel electrode or air electrode production step for producing the fuel electrode 12 or the air electrode 13 by firing, the metal oxide contained in the metallized layer 141 formed by firing the metallized coating film, and reducing the reduced product. Reduction process to be generated , Bonding process and a method for producing a solid electrolyte fuel cell characterized by comprising in this order to the metalized layer 141 and the isolation member 22 are joined by brazing filler metal.
6). 3. 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 an unsintered solid electrolyte layer, the unsintered air electrode or the unsintered fuel electrode, A firing step of integrally firing the unsintered solid electrolyte layer, and a metallized coating film containing the metal oxide on the peripheral edge of the other surface of the solid electrolyte layer 11 formed by firing the unsintered solid electrolyte layer Forming a metallized layer 141 and then firing to form a non-fired fuel electrode or an unfired air electrode on the other surface of the solid electrolyte layer 11, and then firing to form the fuel electrode 12 or A fuel electrode or air electrode production process for producing the air electrode 13, a reduction process for reducing the metal oxide contained in the metallized layer 141 to produce the reduced product, the metallized layer 141 and the isolation member 22. The metal b Joining step and a method for producing a solid electrolyte fuel cell characterized by comprising in this order of joining the wood.
7). The metal oxide contains at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. Thru 6. The manufacturing method of the solid oxide form fuel cell of any one of these.
8). The above reduction step is performed in a reducing atmosphere containing 500 to 1000 ° C. and 0.01 to 7% by volume of hydrogen, with the balance being nitrogen or an inert gas. Thru 7. The manufacturing method of the solid oxide form fuel cell of any one of these.

According to the solid oxide fuel cell of the present invention, the metallized layer 141 is provided by a method that does not cause degradation of the performance of a member such as an air electrode at the time of production, and the bonding property with the isolation member is improved. At the same time, good power generation performance is maintained.
Furthermore, when the reduced product is at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, In, and the like, the bondability with the isolation member can be further improved. it can.
According to the solid electrolyte fuel cell of the present invention, since the solid electrolyte layer and the separating member are joined by the joining layer 14 having high heat resistance and sufficient joining strength, sufficient power generation performance is maintained. The

According to the method for producing a solid oxide 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 oxide fuel cell of the present invention, the metallization comprising a reduced product By providing the layer, the solid electrolyte layer and the separating member can be firmly bonded with the metal brazing material, the bonding layer 14 having high heat resistance can be formed, and the solid electrolyte accompanying the production of the metallized layer By suppressing deterioration of the layer, the fuel electrode, and the air electrode, 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 the other fuel cell manufacturing method of the present invention are particularly useful for manufacturing a fuel electrode-supported fuel cell, and the other fuel cell manufacturing method of the present invention is In particular, it is useful for manufacturing a self-supporting fuel cell.
Further, when the metal oxide contains at least one of Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In, the metal oxide is easily reduced to a metal The solid oxide fuel cell and the separating member can be firmly joined by this metal, 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 volume of hydrogen and the balance being nitrogen or an inert gas, the metal oxide is sufficiently reduced. In addition, the air electrode and the like are not decomposed, and a fuel cell having sufficient power generation performance can be obtained.

Hereinafter, a solid oxide fuel cell of the present invention, a solid electrolyte fuel cell using the same, and a method for manufacturing the same will be described in detail with reference to FIGS.
[1] Solid electrolyte fuel cell and solid electrolyte fuel cell using the same “Solid electrolyte fuel cell” (see, for example, FIG. 1 and FIGS. 4 to 5, hereinafter sometimes referred to as “cell”). ) On the periphery of the solid electrolyte layer 11, the fuel electrode 12 provided on one surface or the other surface of the solid electrolyte layer 11, the air electrode 13 provided on the other surface, and the other surface of the solid electrolyte layer 11. And a metallized layer 141 provided.
The “solid oxide fuel cell 102” (for example, see FIGS. 3 to 5; hereinafter, also referred to as “fuel cell”) is formed by laminating a plurality of solid electrolyte fuel cells 1011. Yes. Furthermore, each fuel cell 102 has an interconnector 211, 212 disposed between each cell, and the fuel gas flow path and the combustion-supporting gas flow path, depending on the battery structure. Isolation separators 221, 222, 223, etc., which are the isolation members.

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, a flat cylindrical cell 1012 can be formed as shown in FIG. 6, or a cylindrical cell 1013 can be formed as shown in FIG.
In the 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 same except that the air electrode 13 is formed inside and the fuel electrode 12 is formed outside. It can also be a cell of 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 fuel 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 fuel 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, 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 the same planar shape as a solid electrolyte layer and an air electrode, and it is preferable that the fuel electrode and the solid electrolyte layer are laminated | stacked on each substantially whole 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 fuel cell at a low temperature in the temperature range of 500 to 850 ° C., and further 500 to 750 ° C. Even when it is used, 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, the same planar shape as a solid electrolyte layer and a fuel electrode is preferable. Furthermore, when the separating member is joined to the peripheral edge of one surface of the solid electrolyte layer, the air electrode is formed smaller than the solid electrolyte layer and the fuel electrode. The air electrode and the solid electrolyte layer are preferably laminated on the entire surface.

The “metallized layer 141” is made of a metal which is the “reduced product” generated by reducing a metal oxide.
The “metal oxide” is a metal oxide that is reduced to produce a metal. By reducing under such conditions, the bondability with the metal brazing material can be improved without deteriorating the air electrode that is easily reduced. Moreover, by providing it in the form of a metal oxide, it can be baked firmly in the atmosphere, and by making it a metal by subsequent reduction, the bondability with the metal brazing material used for joining with the isolation member is improved. Can do.
The metal is not particularly limited as long as it can form a metallized layer having sufficient bondability. 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 volume of hydrogen, with the balance being formed 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 volume, particularly 0.1 to 4% by volume, and more preferably 0.5 to 3% by volume.

The metal oxide that is reduced under such reducing conditions is not particularly limited as long as it is reduced under the above conditions to produce the reduced product. Examples of the metal oxide include Fe ₂ O ₃ , Co ₃ O ₄ , NiO, CuO, and MoO _3. These are reduced to produce metals such as Fe, Co, Ni, Cu, and Mo. .
As the metal oxide, SnO ₂ , ZnO, WO _{3 and the} like can be used in addition to the above various metal oxides, and these are reduced to produce metals such as Sn, Zn and W. In addition, examples of the metal oxide containing two or more kinds of metal elements include double oxides such as CuFe ₂ O ₄ , CuMoO _4, and CuWO ₄ , which are reduced to a mixture of Cu and Fe, Cu Metals such as a mixture of Mo and Mo and a mixture of Cu and W are formed. Furthermore, a metallized layer can be produced using a powder obtained by mixing two or more metal oxides as a raw material. Examples thereof include a mixture of NiO and CuO, a mixture of NiO and Co ₃ O ₄ , and the like. When these are reduced, a Ni—Cu alloy and a Ni—Co alloy are produced.

In addition, this solid oxide fuel cell can be stored as an intermediate product provided with a metallization film made of metal oxide without reducing 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 a portion other than the peripheral portion of the other surface of the solid electrolyte layer, and a peripheral portion of the solid electrolyte layer In the solid oxide fuel cell having the provided metallization coating, the metallization coating may be a solid oxide fuel cell characterized by containing a metal oxide.
In the case of this intermediate product, when it becomes necessary, the 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. Such a cell can suppress deterioration of the metallized layer due to storage or the like and deterioration of the bonding property with the isolation member. In this intermediate product, the description of the solid electrolyte fuel cell of the present invention can be applied as it is to the solid electrolyte layer, the fuel electrode, the air electrode, the metal oxide and the like.

  In the solid oxide fuel cell 102, for example, as shown in FIGS. 3 to 5, a flat solid electrolyte fuel cell 1011 can be connected via interconnectors 211 and 212. The solid oxide fuel cell 102 has an isolation member 22 (see FIG. 2, as shown in FIGS. 3 to 5) for isolating the flow path of the fuel gas and the flow path of the combustion-supporting gas, depending on the battery structure. In the case of a flat plate type, hereinafter referred to as isolation separators 221, 222, and 223), nickel felt layer 31 for electrically connecting interconnectors 211 and 212 and fuel electrode 12, and interconnectors 211 and 212, A current collecting member such as an Inconel fiber mesh layer 32 for electrically connecting the air 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, a 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.

  Moreover, in the cell of FIG. 6, when it is set as the cell of the same structure except forming the air electrode 13 inside and the fuel electrode 12 outside as mentioned above, although it depends on the battery structure, the end of each cell In this part, the peripheral edge of the solid electrolyte layer is joined to a supporting gas introducing / separating member which is 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 using the flat plate cell 1011 shown in FIGS. 1 and 4 to 5, the interconnectors 211, 212, the separators 221, 222, 223 and other parts such as a lid member 23 and a bottom member described later are used. 24 and the like are usually formed of a heat-resistant metal such as stainless steel. These may be formed of a conductive ceramic. 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 the 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 Other members such as an interconnector, a frame, a lid member, and a bottom member are joined directly or indirectly by a metal brazing material to form a joint portion 4.

  Further, an interconnector 213 in a fuel cell using the flat cylindrical cell 1012 of FIG. 6, a fuel gas introduction / separation member 224, an interconnector 214 in a fuel cell using the cylindrical cell 1013 of FIG. Usually, it is made of a heat-resistant metal such as stainless steel. Moreover, you may form with the electroconductive ceramic. Further, in these fuel cells, the metallized layer and the fuel gas introduction / separation member 224 and the like are joined by a metal brazing material to form a joining layer 14 (see, for example, FIG. 8). Are joined directly or indirectly 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 series and MTiO ₃ series (M is a metal element, and M is an alkali such as Sr, Ca, Ba). Earth 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 separating member 22 and the like 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. When 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 bonding layer and a bonding portion having sufficient durability can be formed. Furthermore, the Ag-based brazing material flows sufficiently at the time of bonding, and the sealing properties of the bonding layer and the like 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. Further, 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 the sealing properties such as the bonding layer are improved. Can be improved.

  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 layer or the like 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 present solid electrolyte fuel cell, any layer of the solid electrolyte, fuel electrode, and air electrode constituting each cell can be used as a support substrate. Furthermore, although the power generation efficiency can be increased by making other layers thin or flat, it is not preferable to make the layers excessively thin from the viewpoint of strength. Moreover, it is not preferable to make the solid electrolyte layer thicker from the viewpoint of power generation performance.
In the case of the fuel electrode support type, the thickness of the fuel electrode is preferably 20 times or more that of the solid electrolyte layer. If it is less than 20 times, the mechanical strength of the cell tends to decrease. 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, in the case of the air electrode support type, 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 addition, the thickness of the air electrode is preferably 10 to 100 μm, particularly preferably 20 to 50 μm in the case of the fuel electrode support type. 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.
On the other hand, in the case of the air electrode support type, the thickness of the air electrode is preferably 20 times or more that of the solid electrolyte layer. If it is less than 20 times, the mechanical strength of the cell tends to decrease. 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.

  The above "fuel gas" is hydrogen, a hydrocarbon serving as a hydrogen source, a mixed gas of hydrogen and hydrocarbon, a fuel gas obtained by passing these gases through water at a predetermined temperature and humidifying them, and mixing these gases with water vapor. Fuel gas and the like. 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 “flammable 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.

[2] Method for Producing Solid Electrolyte Fuel Cell The method for producing the solid electrolyte fuel cell is not particularly limited, but can be produced, for example, by the method for producing the solid electrolyte fuel cell of the present invention and other solid oxide fuel cells of the present invention. .
(1) Manufacturing Method of Solid Electrolyte Fuel Cell of the Present Invention One of the manufacturing methods of the solid oxide fuel cell of the present invention is a manufacturing method of an air electrode support type or a fuel electrode support type cell. Alternatively, a laminating step of laminating the unfired fuel electrode and one surface of the unfired solid electrolyte layer, and a coating film forming step of forming a metallized coating film containing a metal oxide on the periphery of the other surface of the unfired solid electrolyte layer A co-firing step in which the air electrode support type or unfired 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 A fuel electrode or air electrode manufacturing step of forming and firing to form a fuel electrode 12 or an air electrode 13, a reduction step of forming a metallized layer 141 by reducing the metal oxide sintered body to form a reduced product, and Metallization layer 141 and isolation member 22 The joining process of joining with a metal brazing material is provided in this order.

(A) Formation of unsintered fuel electrode or unsintered air electrode 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.
Furthermore, each formation method is not specifically limited, Various methods, such as a screen printing method, a doctor blade method, a squeegee method, and a spin coat method, are mentioned.

(B) Lamination process In the said "lamination process", the method of laminating | stacking an unbaked air electrode or an unburned fuel electrode, and one surface of an unbaked solid electrolyte layer is not specifically limited. For example, in the self-supporting type, the slurry for the unsintered air electrode or unsintered fuel electrode may be applied to the unsintered solid electrolyte layer, then dried, and further heated and laminated as necessary. Furthermore, in the fuel electrode support type, the slurry for the unfired solid electrolyte is applied to the unsintered fuel electrode, then dried, and further heated as necessary, so that there is an organic binder contained in the slurry. If it is removed, it can be laminated. In the air electrode support type, the slurry for the unfired solid electrolyte is applied to the unfired air electrode, then dried, and further heated as necessary to remove the organic binder contained in the slurry. It can be laminated by doing.
Further, in the self-supporting type, the unfired fuel electrode is formed by previously forming a sheet that becomes an unfired air electrode or an unfired fuel electrode using the above slurry, and this sheet is laminated on the unfired solid electrolyte layer. You can also. Further, in the fuel electrode support type, the unfired solid electrolyte layer can be provided by forming a sheet to be an unfired solid electrolyte layer in advance using the slurry and laminating the sheet on the unburned fuel electrode. . Furthermore, in the air electrode support type, the unfired solid electrolyte layer is formed by previously forming a sheet that becomes the unfired solid electrolyte layer using the slurry, and this sheet is laminated on the unfired air electrode. You can also.

(C) Coating film formation process In the said "coating film formation process", the method of forming a metallized coating film is not specifically limited. For example, a slurry containing a metal oxide powder such as NiO can be applied and formed on the peripheral portion of the other surface of the unfired solid electrolyte layer. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade method, and a spin coating method can be used.

(D) Co-firing step The above-mentioned "co-firing step" is a step of integrally firing the unfired air electrode or unfired fuel electrode, the unfired solid electrolyte layer, and the metallized coating film. The air electrode 13, the solid electrolyte layer 11, and the metallized layer 141 are formed simultaneously. Although the firing temperature of this co-firing depends on the kind of raw material powder used, etc., it is a case where the above-mentioned various raw materials are used. When the unfired air electrode is moved and fired, it is 1250 to 1500 ° C., particularly 1250 to 1450. It is preferable to set it as 1 degreeC and 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 In the above-mentioned "fuel electrode or air electrode production process", the method for forming the unfired fuel electrode or the unfired air electrode is not particularly limited. For example, a slurry containing various metal powders, metal oxide powders, metal double oxide powders, and the like is applied to the other surface of the solid electrolyte layer 11, then dried, and further heated as necessary. be able to. 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.
Firing of the unfired fuel electrode or unfired air electrode, and firing conditions of the unfired fuel electrode or 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 fuel electrode 12 or air electrode is already fired. 13 and the like are not excessively densified by the firing, and gas diffusion in the fuel electrode 12 or the air electrode 13 is not impaired.
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.

(F) Reduction Step In the above “reduction step”, the method of reducing the metal oxide contained in the metallized layer 141 to generate a reduced product is that the metallized layer 141 improves the bonding property between layers and functions as a conductive layer. There is no particular limitation. This metal oxide can be reduced in an atmosphere having a temperature of 500 to 1000 ° C., containing 0.01 to 7% by volume of hydrogen, and 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. In addition, the hydrogen content in the reducing atmosphere is preferably 0.05 to 5% by volume, particularly 0.1 to 4% by volume, and more preferably 0.5 to 3% by volume. Further, the temperature is preferably 550 to 950 ° C., and the hydrogen content is preferably 0.05 to 5% by volume, the temperature is 600 to 850 ° C., and the hydrogen content is 0.1 to 4%. More preferably, it is volume%, it is especially preferable that temperature is 650-750 degreeC, and content of hydrogen is 0.5-3 volume%.

(G) Joining Step The “joining step” is a step of joining the metallized layer 141 and the isolation member 22. 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. An unfired air electrode or an unfired fuel electrode is provided on one surface of the solid electrolyte layer 11 and a metallized coating film containing a metal oxide is formed on the periphery of the other surface of the unfired solid electrolyte layer. Firing air electrode or unfired fuel electrode / metallized coating film forming process, unburned air electrode or unfired fuel electrode and metallized coating film firing process, unburned fuel electrode or unfired on the other surface of the solid electrolyte layer 11 A fuel electrode or air electrode manufacturing step in which an air electrode is formed and fired to produce the fuel electrode 12 or the air electrode 13, a metal oxide sintered body is reduced to produce a reduced product, and a metallized layer 141 is formed. Process and metallization layer 1 41 and the separating member 22 are joined in this order.

(A) Solid electrolyte layer preparation process The above-mentioned "solid electrolyte layer preparation process" is a process of preparing the solid electrolyte layer 11 by baking an 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 ceramics, LaGaO ₃ -based ceramics, etc. is applied to the surface of a support material such as a resin sheet, rubber sheet and glass, and then dried and further heated as necessary. When the slurry contains an organic binder or the like, it can be formed by removing the organic binder or the like. The coating method is not particularly limited, and various methods such as a screen printing method, a doctor blade 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 air electrode or unsintered fuel electrode / metallized coating film forming step In the “unsintered air electrode or unsintered fuel electrode / metallized coating film forming step”, the unsintered air electrode or unsintered fuel electrode is formed. The method is not particularly limited. For example, the unfired fuel electrode contains 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 metal oxide powder such as NiO is applied to the peripheral edge of the other surface of the solid electrolyte layer 11, then dried, and further heated as necessary, and an organic binder contained in the slurry, etc. It can be formed by removing. The coating method is not particularly limited, and various methods such as a screen printing method and a spin coating method can be used.

(C) Firing step The fuel electrode 12 or the air electrode 13 and the metallized layer 141 are formed by integrally firing the unfired air electrode or the unfired fuel electrode and the metallized coating film by the “firing step”. The The firing temperature depends on the type of raw material powder to be used, but when the above-mentioned various raw materials are used and the unfired fuel electrode is fired, it is 1200 to 1450 ° C, particularly 1200 to 1400 ° C, and further 1250. It is preferable to set it to -1400 degreeC. If a calcination temperature is 1250-1450 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 The above-mentioned "air electrode production process", "reduction process" and "joining process" This is the same as (E) fuel electrode or air electrode production process, (F) reduction process, and (G) joining process in the manufacturing method.

(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 A metallized coating film containing a metal oxide is formed on the peripheral edge of the surface, and then fired to form a metallized layer 141. On the other surface of the solid electrolyte layer 11, the unfired fuel electrode or unfired A fuel electrode or air electrode manufacturing step in which an air electrode is formed and then fired to prepare the fuel electrode 12 or the air electrode 13, and a metal oxide reduced product obtained by reducing the metal oxide contained in the metallized layer 141. Reducer to produce And a joining step of joining the metallized layer 141 and the isolation member 22 with a metal brazing material in this order.

In the above manufacturing method, the description regarding each step in the manufacturing method of the solid electrolyte fuel cell of the present invention can be applied as it is to the stacking step, the reduction step, the joining step, and the fuel electrode or air electrode manufacturing 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 metal oxide on the peripheral portion of the other surface of the solid electrolyte layer and firing the metallized coating film. As for this metal oxide, the description in the case of the solid oxide fuel cell can be applied as it is.
In the above solid oxide fuel cell manufacturing method, the materials used for forming the solid electrolyte layer, the fuel electrode, the air electrode, and the metal oxide, etc., are the same as those in the case of the solid oxide fuel cell. Can be applied. 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 relating to a flat plate type fuel cell and a fuel cell will be specifically described by way of examples.
[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 prepared by blending zirconia (hereinafter referred to as “8YSZ”) powder in which 8 mol% of yttria is solid-dissolved with diethylamine as a dispersant and toluene and methyl ethyl ketone as organic solvents. Dibutyl phthalate as an agent and polyvinyl alcohol as a binder were blended and further prepared by a doctor blade method using a slurry prepared by mixing. The unfired fuel electrode was prepared by mixing nickel oxide (NiO) powder and the above 8YSZ powder, and then mixing artificial graphite powder as a pore former and further mixing. Subsequently, it produced by the screen-printing method using the slurry which mix | blended butyl carbitol as a solvent.

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. Moreover, the metallized coating film used as a metallized layer is a metal oxide powder [NiO powder (metal Ni is produced by reduction) described in the column of the metallized layer in Table 2 or a mixed powder of NiO and Co ₃ O ₄ ( Reduction produced metal Ni and metal Co))] and a slurry in which butyl carbitol was blended as a solvent.

(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 each green body, and solid electrolyte 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) Peel test Using the test body prepared in (1) above, a cloth adhesive tape was attached to the entire surface of the metallized layer, and then peeled to perform a peel test. 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
Note that the unfired metallized layers of Reference Examples 1 to 5 are not reduced and remain as metal oxides, and thus have no function as a metallized layer, but are referred to as a metallized layer for convenience.

According to the results in Table 2, regardless of the cell preparation procedure and the type of metal oxide used for forming the metallized layer, the remaining rate after the peel test is 100%, and the metallized layer is sufficient for the solid electrolyte layer. It turns out that it adheres to.
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 existence of constituent phases generated due to lack of oxygen such as Sr ₂ Co ₂ O ₅ and La ₂ Co ₂ O ₄ 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] Joining strength (breaking strength) between the solid electrolyte layer of the solid electrolyte fuel cell and the separator for the test cell and the power generation performance of the cells Examples 6 to 11 and Comparative Examples 4 to 6
(1) Manufacture of solid electrolyte fuel cell (test cell) After pressing using zirconia powder stabilized with 10 mol% scandia, pressure of 1500 kg / cm ^{2 by} cold isostatic pressing To form a green solid electrolyte layer. 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, an unsintered fuel electrode was formed concentrically with the unsintered solid electrolyte layer on one surface of the unsintered solid electrolyte layer by screen printing using this slurry.

Thereafter, butyl carbitol as a solvent was mixed with the metallized material (metal oxide) shown in Table 3 to prepare a slurry for the metallized coating film.
Next, 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. Then, it hold | maintained at 1400 degreeC in the air atmosphere for 1 hour, and baked integrally, and the sintered compact for Examples 6, 8, 9, and 11 was obtained. 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.
In addition, after firing the laminate of the unsintered solid electrolyte layer and the unsintered fuel electrode under the above conditions, a metallized coating film is formed concentrically with the unsintered solid electrolyte layer using the slurry, and then fired under the above conditions. As a result, sintered bodies for Examples 7 and 10 were obtained.

Next, a slurry was prepared by mixing polyvinyl alcohol as a binder with La _0.6 Sr _0.4 (Co _0.2 Fe _0.8 ) O ₃ powder. Thereafter, an unsintered air electrode was formed concentrically with the solid electrolyte layer 11 on the other surface of the solid electrolyte layer 11 by screen printing using this slurry. Subsequently, the air electrode 13 having a diameter of 10 mm and a thickness of 15 μm was formed by holding at 1100 ° C. for 1 hour and firing. Thereafter, heating to 700 ° C. in a reducing atmosphere composed of 2% by volume of hydrogen and 98% by volume of nitrogen to reduce the metallized material (metal oxide), generate Ni or Co, and form the metallized layer 141. A test cell was produced.

(2) Joining of Test Cell Separator As shown in FIG. 10, the test cell manufactured in the above (1) comprises a metallized layer 141 formed on the edge of the other surface of the solid electrolyte layer 11 and SUS430. Test cell separator 81 (in the solid oxide fuel cell 102 described later, a metal separator corresponding to the separators 221, 222, and 223, an outer diameter of 40 mm, a thickness of 50 μm, and an opening having a diameter of 12 mm in the center) Was formed by brazing at 1100 ° C. in a vacuum atmosphere using a metal brazing material described in Table 3.

(3) Electron microscope observation of the bonding interface The bonding layer formed by brazing in (2) above is fixed with resin including peripheral members, and then cut from the test cell separator 81 toward the fuel electrode, The cross section was mirror-polished and observed with an electron microscope. As a result, the test cell separator 81 and the metallized layer 141 were integrated with each other so that the respective bonding interfaces could not be confirmed. Thus, it was found that the solid electrolyte layer 11 and the test cell separator 81 were firmly joined.

(4) Measurement of bonding strength The bonding strength was measured for each of Examples 6 to 11 and Comparative Examples 4 to 6 for the test cells to which the test cell separator 81 produced in (2) above was bonded.

  As shown in FIG. 11, the test cell separator 81 produced in the above (2) is 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 was joined so that the outer periphery of the support base 82 and the outer periphery of the test cell separator 81 coincided, and then the upper surface of the air electrode 13 was made of SUS430 having a diameter of 10 mm and a height of 10 mm. Next, a load is applied from above the load loading jig 83, the load when the solid electrolyte layer 11 is peeled from the test cell separator 81 is measured, and the load is divided by the bonding area. Calculated. The results are also shown in Table 3 as an average value of five 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 produced in the above (2) are passed through an alumina tube seal portion 85 made of seal glass. After being sandwiched between the outer alumina tubes 841, 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 power, and electricity was taken out from the platinum wire 862 connected to the platinum net 861 to obtain the maximum output density. In this test cell, since LSCF or the like is used for the air electrode 13, it can be operated at a lower temperature. Therefore, the power generation performance was evaluated at 700 ° C. The results are also shown in Table 3.

According to the results of Table 3, in Examples 6 to 11, the bonding strength was 483 to 502 kPa / mm ² , the difference between the integral firing or the separate firing of the metallized layer 141 and another layer, and the metallized material (metal It can be seen that sufficient bonding strength is provided regardless of the type of the oxide) and the metal brazing material.
On the other hand, in Comparative Example 4 in which the solid electrolyte layer 11 and the test cell separator 81 were directly joined without a metallized layer, the joining strength was extremely low at 51 kPa / mm ^2, and the solid electrolyte layer 11 and the test cell separator 81 were Easy to peel.
Further, in Comparative Example 5 in which the solid electrolyte layer 11 and the test cell separator 81 are joined through a metallized layer formed by ordinary electroless Ni plating, the joining strength is as high as 480 kPa / mm ² , but it is used at the time of plating. Part of the air electrode was dissolved by the nitric acid.
Further, in Comparative Example 6 in which the solid electrolyte layer 11 and the test cell separator 81 are joined through a metallized layer formed by a normal Mo-Mn method, the joining strength is as high as 491 kPa / mm ² , but power generation performance to be described later The deterioration rate of was remarkable.

Moreover, according to the evaluation of the power generation performance using the test bodies of Examples 6 to 11 and Comparative Examples 4 to 6, Comparative Example 4 in which the solid electrolyte layer 11 and the test cell separator 81 were directly joined without a metallized layer. Based on the power generation output of 0.33 W / cm ² , the deterioration rate expressed as a percentage of the reference value is 0 to 6% at the maximum in Examples 6 to 11, indicating that the deterioration rate 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 A fuel electrode-supported solid electrolyte fuel cell manufactured by the method for manufacturing a solid electrolyte fuel cell of the present invention is used, and the solid electrolyte fuel cell has three. An internal manifold type solid oxide fuel cell was manufactured.
(1) Structure of fuel cell (a) Cell and various separators FIG. 3 is a perspective view showing the appearance of a flat-plate solid electrolyte fuel cell 102 having a structure in which three cells are stacked. 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 solid oxide fuel cell 102, three cells 1011 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 is provided as an isolation member joined to the lid member 23. Further, the solid electrolyte layer 11 and the upper cell isolation separator 221 are bonded via a bonding layer 14 including a metallized layer 141 and a brazing layer 142 as shown in FIG.
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. It has an intermediate cell isolation separator 222 that is an isolation member joined to the interconnector 211. Furthermore, the solid electrolyte layer 11 and the intermediate cell isolation separator 222 are joined together via a joining layer 14 including a metallized layer 141 and a brazing layer 142 as shown in FIG.
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. Further, the lower cell isolation, which is an isolation member whose lower surface is bonded to the solid electrolyte layer 11 and the metal frame 66 and whose upper surface is bonded to the interconnector 212 via the ceramic frame 53 and the metal frame 65. A separator 223 is included. Further, the solid electrolyte layer 11 and the lower cell isolation separator 223 are bonded via a bonding layer 14 including a metallized layer 141 and a brazing layer 142 as shown in FIG.

  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 bonded at 1100 ° C. in a vacuum atmosphere to form a bonding layer 14. 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 this fuel cell, when another cell is further 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 this embodiment, the fuel gas introduction pipe 71 and the fuel gas discharge pipe 72, and the combustion support gas introduction pipe 73 and the combustion support gas discharge pipe 74 are respectively in the diagonal direction. It is attached to the position where it circulates. 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 the Fuel Cell In this flat plate fuel cell 102 stack, 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 on the solid electrolyte layer and the separating member are bonded at 1100 ° C. in a vacuum atmosphere using a metal brazing material, thereby forming the bonding layer 14. ing.
It is considered that compressive stress remains in each of the bonding layers 14. Thereby, it can be set as the strong stack structure which can endure various external forces.

  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 or the like 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 the flat type solid oxide fuel cell of this invention. It is a schematic diagram which shows a part of cross section of the conjugate | zygote which joined the isolation member to the solid electrolyte layer of the flat type solid electrolyte form fuel cell of the present invention. 1 is a perspective view showing a solid electrolyte fuel cell of a flat plate and a fuel electrode support type. FIG. It is a schematic diagram which shows the AA cross section of the solid electrolyte form fuel cell of FIG. It is a schematic diagram which shows the BB cross section of the solid oxide fuel cell of FIG. It is a schematic diagram which shows the cross section (The interconnector is arrange | positioned.) Of the other example (flat cylindrical type) of the solid oxide fuel cell of this invention. FIG. 7 is a perspective view showing a state in which three solid oxide fuel cells of FIG. 6 are connected via an interconnector, and a fuel gas introduction / separation member is disposed at the lower part. 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 type) of the solid oxide fuel cell of this invention. It is a model perspective view for demonstrating the structure of the cell for a test, and the separator for a test cell. It is a schematic diagram which shows the cross section of the test body which measures joining strength. In addition, the downward arrow at the top of the load loading jig represents the load direction. 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 (reduced product) 142; brazing layer, 21, 211, 212, 213, 214; interconnector, 22; isolation member, 221; isolation separator for upper cell (isolation member), 222; isolation separator for intermediate cell (isolation member), 223 ; Bottom cell isolation separator (separation member), 23; lid member, 24; bottom member, 31; nickel felt layer, 32; inconel fiber mesh layer, 4; joint, 51, 52, 53; 61, 62, 63, 64, 65, 66; metal frame, 71; fuel gas introduction pipe, 72; fuel gas exhaust pipe, 73; combustion-supporting gas introduction pipe, 74; Flammable gas exhaust pipe, 81; separator for test battery, 82; support base, 83; jig for load application, 841; outer alumina pipe, 842; inner alumina pipe, 85; seal section for alumina pipe, 861; Net, 862; platinum wire.

Claims (8)

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 reduced metal oxide, and is a solid oxide fuel cell.   2. The solid oxide fuel cell according to claim 1, wherein the reduced product is at least one metal selected from Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. A solid oxide fuel cell comprising a structure in which the solid oxide fuel cell according to claim 1 or 2 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 3,
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 the 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 unfired 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 metal oxide contained in the metallized layer 141 formed by firing the metallized coating film to generate the reduced product;
A solid oxide fuel cell manufacturing method 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 3,
A solid electrolyte layer preparation step of baking the unfired solid electrolyte layer to prepare the solid electrolyte layer 11;
An unsintered metal electrode 11 is provided with an unsintered air electrode or an unsintered fuel electrode, and a metallized coating film containing the metal oxide is formed on the periphery of the other surface of the unsintered solid electrolyte layer 11. Air electrode or unfired fuel electrode / metallized coating film forming process,
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 in which a non-fired fuel electrode or a non-fired air electrode is formed on the other surface of the solid electrolyte layer 11 and then fired to produce the fuel electrode 12 or the air electrode 13;
A reduction step of reducing the metal oxide contained in the metallized layer 141 formed by firing the metallized coating film to generate the reduced product;
A solid oxide fuel cell manufacturing method 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 3,
A laminating step of laminating the unsintered air electrode or unsintered fuel electrode and unsintered solid electrolyte layer;
A firing step of integrally firing the unfired air electrode or the unfired fuel electrode and the unfired solid electrolyte layer;
A metallized layer is formed by forming a metallized coating film containing the metal oxide on the peripheral portion of the other surface of the solid electrolyte layer 11 formed by firing the unsintered solid electrolyte layer, and then firing to form a metallized layer 141 Forming process;
A fuel electrode or air electrode manufacturing step in which a non-fired fuel electrode or a non-fired air electrode is formed on the other surface of the solid electrolyte layer 11 and then fired to produce the fuel electrode 12 or the air electrode 13;
A reduction step of reducing the metal oxide contained in the metallized layer 141 to generate the reduced product;
A solid oxide fuel cell manufacturing method comprising: a joining step of joining the metallized layer 141 and the isolation member 22 with a metal brazing material in this order.   7. The metal oxide according to claim 4, wherein the metal oxide contains at least one metal element selected from Fe, Co, Ni, Cu, Mo, Sn, Zn, Ga, W, and In. The manufacturing method of the solid electrolyte form fuel cell of description.   The said reduction | restoration process is 500-1000 degreeC, and contains 0.01-7 volume% hydrogen, and is any one of the Claims 4 thru | or 7 made in the reducing atmosphere whose remainder is nitrogen or an inert gas. A method for producing a solid oxide fuel cell as described in 1).

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