JP2006202727A - Solid electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel cell which is sealed sufficiently by a metal sealing material and reduced in thermal hysteresis due to brazing or the like, and has high temperature uniformity. <P>SOLUTION: The solid electrolyte fuel cell is provided with a plurality of unit cells having a solid electrolyte layer 11 (made of ZrO<SB>2</SB>based ceramic or the like), a fuel electrode 12 (made of a mixture of Ni and ZrO<SB>2</SB>based ceramic) installed on one face, and an air electrode 13 (made of a double oxide such as La<SB>0.6</SB>Sr<SB>0.4</SB>Co<SB>0.2</SB>Fe<SB>0.8</SB>O<SB>3±δ</SB>or the like) installed on the other face, a separator (made of stainless steel or the like) installed between the unit cells, and a gas seal part 2 composed of a metal sealing material (made of Ag, Au, Cu or the like or an alloy containing these or the like) installed on at least one face of this separator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell. More specifically, in the present invention, a metal sealing material is disposed on at least one surface of the separator, and the gas sealing is performed by the metal sealing material instead of the joining by the metal brazing material or the like. The present invention relates to a solid oxide fuel cell that is prevented and maintains good power generation performance.

  A flat plate type solid oxide fuel cell (hereinafter also referred to as “fuel cell”) is formed by stacking a plurality of cells using an interconnector. In this fuel cell, gas sealing is performed for the purpose of isolating the flow path of the fuel gas introduced into the fuel electrode from the flow path of the oxidizing gas introduced into the air electrode. For this gas seal, a metal brazing material, a glassy gas seal material, or the like is used. In this case, the members to be gas sealed are firmly joined. In addition, the gas seal may be made with ceramics interposed between members (for example, see Non-Patent Document 1 and Patent Document 1). In this case, since the members are not joined, bolts, nuts, etc. It is necessary to hold the laminated structure by other means such as pressing and fixing in the laminating direction.

  Furthermore, it has the seal part which consists of specific powder, and the shape maintenance part arrange | positioned on both sides of this seal part, and maintains the shape of a seal part, and a seal part and a shape maintenance part are to-be-sealed members A gas seal structure for a high-temperature fuel cell that is compressed between the two is known (for example, see Patent Document 2). According to this gas seal structure, it is described that the gas seal structure has durability against thermal expansion / contraction when starting and stopping, rapid start-up and vibration.

  In recent years, studies have been made to reduce the internal resistance by using a solid electrolyte layer made of yttria-stabilized zirconia or the like as thin as possible to reduce the internal resistance and operate the fuel cell in a relatively low temperature range of, for example, 800 ° C. or lower. Thus, when operating at a low temperature, a metal interconnector instead of a ceramic can be used. In particular, if an inexpensive interconnector made of stainless steel can be used, the cost can be reduced.

J. et al. Mater. Res. , Vol. 18, no. 9, Sep. 2003 JP-T-2004-506308 JP 2002-203581 A

  However, when a glassy gas seal material is used, it may be damaged by thermal stress. In addition, when this glassy gas seal material and metal brazing material are used for joining, the cells cannot be removed when some of the cells are damaged or the performance deteriorates. May become unusable. Further, when mica is used as a gas sealing material as described in Non-Patent Document 1, there is a case where sufficient sealing cannot be performed unless the surface roughness of the member to be gas sealed is high.

  Furthermore, when the gas seal material in which the non-sintered ceramic particles are held in the ceramic fiber matrix described in Patent Document 1 is used, there may be a case where sufficient sealing cannot be performed, and the non-sintered ceramic particles are introduced. The power generation performance may be lowered by floating together with the gas and adhering to the fuel electrode and the air electrode. Further, in the gas seal structure having the seal part and the shape maintaining part described in Patent Document 2, when compressed between the members to be sealed, the seal part and the shape maintaining part are similarly deformed to cause the gas seal structure. If the deformation of the seal portion is small, a seal failure may occur. If the deformation of the shape maintaining portion is small, powder in the seal portion may flow out.

  The present invention has been made in view of the above situation, and a metal sealing material is disposed on the surface of the separator, and is not bonded by a metal brazing material or the like, but is gas-sealed by this metal sealing material. An object of the present invention is to provide a solid oxide fuel cell capable of maintaining power generation performance. In addition, since the number of joints by brazing can be reduced, the thermal history is reduced, and the heat distribution of the entire battery is reduced compared to the case where gas sealing is performed using ceramics having low thermal conductivity, that is, thermal uniformity. It is an object of the present invention to provide a solid oxide fuel cell in which good power generation performance is maintained.

The present invention is as follows.
1. A plurality of single cells having a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, and an air electrode provided on the other surface of the solid electrolyte layer; a separator provided between the single cells; A solid oxide fuel cell comprising: a gas seal portion made of a metal seal material disposed on at least one surface of the separator.
The gas seal portion is formed by pressing a metal seal material. For example, as in the case of using a metal brazing material, the metal material is melted and solidified to join the members. It is completely different from the department.
2. 1. The metal sealing material is a metal foil material. A solid oxide fuel cell according to 1.
3. 1. The metal sealing material is a metal wire. A solid oxide fuel cell according to 1.
4). 1. A groove portion is formed in the separator. To 3. The solid oxide fuel cell according to any one of the above.
5. The metal sealing material is an alloy containing 0.5% by mass or more of Ag, Au, Cu, Ni, Pt, or at least one of Ag, Au, Cu, Ni, and Pt. To 4. The solid oxide fuel cell according to any one of the above.
6). The metal sealing material includes a core material and a coating layer provided on the surface of the core material, and the coating layer includes Ag, Au, Cu, Ni, Pt, or Ag, Au, Cu, Ni, and Pt. 1. An alloy containing 0.5% by mass or more of at least one of the above 1. To 5. The solid oxide fuel cell according to any one of the above.
7). 6. The core described above in which the core is a tubular body or a C-shaped section. A solid oxide fuel cell according to 1.
8). The metal sealing material is positioned by positioning means. To 7. The solid oxide fuel cell according to any one of the above.

The solid oxide fuel cell of the present invention can be sufficiently gas-sealed by a metal sealing material disposed on at least one surface of a separator such as an interconnector, and can reduce the number of places to be joined by brazing or the like. The heat history due to attachment or the like is reduced, the temperature uniformity of the entire battery is high, and good power generation performance is maintained. In addition, since the members sealed by the gas seal portion can be easily separated, when some cells are damaged or the performance is deteriorated, other cells can be removed or removed after the other By incorporating the cell, it can be used as it is as a solid electrolyte fuel cell.
Moreover, when a metal sealing material is a metal foil material and a metal wire, a gas seal part can be formed more easily.
Furthermore, when the groove is formed in the separator, gas sealing can be performed more reliably, and good power generation performance is maintained.
Further, when the metal sealing material is Ag, Au, Cu, Ni, Pt or an alloy containing 0.5% by mass or more of at least one of Ag, Au, Cu, Ni, and Pt, the deformation is caused. An easy and inexpensive metal sealing material can be obtained, gas sealing performance can be further improved, and good power generation performance is maintained.
Further, the metal sealing material includes a core material and a coating layer provided on the surface of the core material, and the coating layer is made of Ag, Au, Cu, Ni, Pt, or Ag, Au, Cu, Ni, and Pt. In the case of an alloy containing 0.5% by mass or more of at least one of them, gas sealing is more sufficiently performed and good power generation performance is maintained.
Further, when the core material is a tubular body or a C-shaped section, deformation is particularly easy, gas sealing is more sufficiently performed, and good power generation performance is maintained.
Furthermore, when the metal sealing material is positioned by the positioning means, the position to be gas-sealed can be reliably sealed, and good power generation performance is maintained.

Hereinafter, the present invention will be described in detail with reference to FIGS.
The solid electrolyte fuel cell of the present invention (for example, the fuel cell 101 of FIGS. 1 and 6 to 8 and the fuel cell 102 of FIGS. 11 to 13) is a fuel provided on one surface of the solid electrolyte layer 11 and the solid electrolyte layer 11. A gas comprising a plurality of single cells having air electrodes 13 provided on the other surface of the electrode 12 and the solid electrolyte layer 11, a separator provided between the single cells, and a metal sealing material provided on at least one surface of the separator. And a seal portion 2.

The “single cell” includes a solid electrolyte layer 11, a fuel electrode 12 provided on one surface of the solid electrolyte layer 11, and an air electrode 13 provided on the other surface of the solid electrolyte layer 11.
The “solid electrolyte layer 11” has ion conductivity capable of moving a part of one of the fuel gas introduced into the fuel electrode or the oxidizing gas introduced into the air electrode as an ion during the operation of the battery. . 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 an oxidizing 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 planar shape of the solid electrolyte layer 11 is not particularly limited, and may be a circle, an ellipse, a polygon such as a triangle and a rectangle, and the like. The planar shape of the solid electrolyte layer 11 is often a quadrangle such as a square or a circle.

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, Cu, 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 planar shape of the fuel electrode is not particularly limited, but is preferably the same shape as the solid electrolyte layer and the air electrode. The dimension in the plane direction can be the same as that of the solid electrolyte layer and the fuel electrode or can be different depending on the structure of the solid oxide fuel cell. The fuel electrode and the solid electrolyte layer are preferably laminated on the entire surface.

The material used for forming 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.

Further, Among these mixed _{oxide, 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 among _3-based mixed oxide is _represented by _{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, More preferably, Ln is at least one of La, Pr and Sm. 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 planar shape of the air electrode is not particularly limited, but is preferably the same shape as the solid electrolyte layer and the fuel electrode. The dimension in the plane direction can be the same as that of the solid electrolyte layer and the fuel electrode or can be different depending on the structure of the solid oxide fuel cell. For example, when the interconnector is joined to the periphery 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.

  In the solid oxide fuel cell, it is not preferable that each single cell be excessively thin from the viewpoint of strength. Therefore, the supporting layer for maintaining the strength is in a self-supporting type in which the solid electrolyte layer is a solid electrode layer, a fuel electrode supporting type in which the supporting layer is a fuel electrode, and an air electrode supporting type in which the supporting layer is an air electrode. . From the viewpoint of power generation performance, it is not preferable to increase the thickness of the solid electrolyte layer. Therefore, from this viewpoint, the fuel electrode support type or the air electrode support type is preferable.

  In the self-standing type, 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 in consideration of electric resistance and strength. Moreover, when it is a fuel electrode support type or an air electrode support type, the thickness of a solid electrolyte layer can be 5-100 micrometers, Especially 5-50 micrometers, Furthermore, it can be 5-30 micrometers.

  In the fuel electrode support type, the fuel electrode is preferably 20 times or more thicker than the solid electrolyte layer. If it is less than 20 times, the mechanical strength of the single cell tends to be insufficient. The thickness of the fuel electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, an air electrode support type can also be used as described below. In this case, the thickness of the fuel electrode is preferably 10 to 50 μm, particularly preferably 20 to 40 μm. If this thickness is 10 to 50 μm, it functions sufficiently as an electrode and does not need to be thicker than 50 μm.

  In 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 single cell tends to be insufficient. The thickness of the air electrode is preferably 200 to 3000 μm, particularly 500 to 2000 μm. If it is less than 200 μm, it will not function effectively as a substrate, and if it exceeds 3000 μm, the power generation efficiency per volume tends to decrease. On the other hand, in the case of the fuel electrode support type, the thickness of the air electrode is preferably 10 to 100 μm, particularly preferably 20 to 50 μm. When the thickness is less than 10 μm, the electrode may not function sufficiently, and when the thickness exceeds 100 μm, the solid electrolyte layer may be peeled off.

  This fuel cell is particularly preferably a fuel electrode support type. When the fuel cell support type is a thin layer of 5 to 100 μm, particularly 5 to 50 μm, and further 5 to 30 μm, the solid electrolyte fuel The battery can be operated at a low temperature of 900 ° C. or lower, particularly 850 ° C. or lower, and further 800 ° C. or lower. Further, this fuel electrode support type can be operated at 750 ° C. or lower, particularly 700 ° C. or lower (usually 500 ° C. or higher).

  The solid electrolyte fuel cell of the present invention has a plurality of single cells, and each single cell is laminated using the “separator”. This separator has a function of isolating each flow path of the fuel gas and the oxidizing gas. The separator may or may not have conductivity. Moreover, the gas flow path may be provided or may not be provided. Examples of the separator include an interconnector, a fuel frame, and an air frame used in the embodiments. Furthermore, in the case of a configuration in which openings serving as fuel gas and oxidizing gas flow paths are formed in the solid electrolyte layer, and a metal sealing material is disposed on both surfaces of the solid electrolyte layer, the solid electrolyte layer serves as a separator.

The material of the separator is not particularly limited, and a refractory metal, a conductive ceramic, or the like can be used.
The refractory metal 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.

The conductive ceramic is not particularly limited, LnMO ₃ such LaCrO ₃ (where, Ln is a rare earth element, La, Pr, Nd and Yb, and the like. Further, M is a metal element, Cr, Mg, Ni, Fe, etc.) are included.
These various refractory metals and conductive ceramics can be selected depending on the structure of the solid oxide fuel cell.

  The “gas seal portion 2” in the fuel cell of the present invention is made of a metal seal material disposed on at least one surface of the separator. By this gas seal portion 2 and the joint portion 5 formed using a metal brazing material or the like, leakage of the fuel gas from the fuel gas introduction pipe 81 and the fuel gas discharge pipe 82 as described later, and the inside of the fuel cell Leakage of fuel gas from the outside is prevented. Further, the gas seal portion 2 and the joint portion 5 prevent leakage of the oxidizing gas from the oxidizing gas introduction pipe 83 and the oxidizing gas discharge pipe 84 and the leakage of the oxidizing gas from the inside to the outside of the fuel cell as will be described later. Is done.

  The “metal sealing material” is not particularly limited as long as it does not melt at the operating temperature of the solid oxide fuel cell. Examples of the metal material constituting the metal sealing material include Ag, Au, Cu, Ni, Pt, Cr, Pd, Mo, Fe, Al, and Co. In addition, an alloy containing 0.5% by mass or more, particularly 30% by mass or more, and further 60% by mass (usually 80% by mass or less) of at least one of Ag, Au, Cu, Ni, Pt, and Pd is given. It is done. Among these, Ag, Au, Cu, Ni, Pt, or at least one of Ag, Au, Cu, Ni, and Pt is 0.5% by mass or more, particularly 30% by mass or more, and further 60% by mass ( Usually, an alloy containing 80% by mass or less) is preferable because gas sealing is sufficiently performed and leakage of fuel gas and oxidizing gas is prevented.

The shape of the metal sealing material is not particularly limited as long as the gas sealing portion 2 can be easily formed on the surface of the separator. Examples of such a metal sealing material include a metal foil material and a metal wire material.
The material of the metal foil material is not particularly limited as long as it is a metal that is in close contact with the separator or the like by pressing and can easily form the gas seal portion 2. As such a metal, the metal and alloy described as a metal material are preferable. If the metal and alloy are used, gas sealing is sufficiently performed and leakage of fuel gas and oxidizing gas is prevented. The metal foil material is Ag, Au, Cu, Ni that is easily deformed by pressing, or at least one of Ag, Au, Cu, and Ni is 0.5% by mass or more, particularly 30% by mass or more, and further 60 More preferably, it is made of an alloy containing mass% (usually 80 mass% or less). Further, the metal foil material is 0.5% by mass or more, particularly 30% by mass or more, and more preferably 60% by mass (usually 80% by mass or less) of Ag, Cu, or Ag and Cu excellent in spreadability. It is particularly preferable that it is made of an alloy containing it.

  The metal foil material preferably has positioning means. The positioning means is not particularly limited as long as the metal foil material can be disposed so that the gas seal portion 2 is formed at a predetermined position. Examples of the positioning means include a method in which the planar shape of the metal foil material is a shape that can be positioned relative to the separator. Examples of the planar shape include a shape in which the outer peripheral line of the metal foil material and the outer peripheral line of the separator overlap at least partly over a predetermined length, preferably over the entire periphery (see FIG. 10). . Moreover, the method etc. which fit and position the convex part provided in the predetermined position of the surface of a separator, and the hole (refer FIG. 15, 16) provided in the predetermined position of the metal foil material etc. are mentioned.

  The metal foil material may be a foil material comprising a core material and a coating layer provided on the surface of the core material. The coating layer may be provided on only one of the front and back surfaces of the core material, but is preferably provided on both the front and back surfaces. If a coating layer is provided on the surface of the core material, particularly on both the front and back surfaces, it functions sufficiently as a metal sealing material. The coating layer may or may not be provided on the side surface of the core material. However, since the core material is generally thin, the coating layer is usually also formed on the side surface of the core material. The method for providing the coating layer is not particularly limited, and examples thereof include a method of plating a metal material on the core material and vapor deposition. The material of the core material is not particularly limited as long as the coating layer can be easily deformed by pressing and the metal foil material can adhere to the separator. This core material can be formed of stainless steel, nickel-base alloy, chromium-base alloy, or the like.

  The covering layer can be formed of a metal that can be easily deformed. This coating layer can be formed from the metals and alloys described as metal materials. These metals and alloys can be easily deformed by pressing, and the formed gas seal portion 2 can sufficiently prevent leakage of fuel gas and oxidizing gas. Further, the coating layer is preferably made of a soft metal such as Ag, Cu and Au, and at least one of Ag, Cu, or Ag and Cu having excellent spreadability is 0.5% by mass or more, particularly 30% by mass. It is particularly preferable to be made of an alloy containing at least 60% and further 60% by mass (usually 80% by mass or less). This metal foil material is particularly preferably one in which the core material is made of stainless steel and the coating layer is made of Ag or Cu. Such a metal foil material has sufficient strength, and the formed gas seal portion 2 prevents leakage of fuel gas and oxidizing gas.

  The thickness of the metal foil material (when the metal foil material is composed of a core material and a coating layer provided on the surface of the core material) is not particularly limited, but 20 to 500 μm, particularly 100 to 100 μm. It can be 300 μm. If the thickness of the metal foil material is 20 to 500 μm, the metal foil material is easily deformed and is in close contact with a separator or the like, and a gas seal is sufficiently achieved. Moreover, when it consists of a core material and a coating layer, the thickness of a coating layer is although it does not specifically limit, It is preferable that it is 10 to 90% of the whole thickness, especially 60 to 80%. If the thickness of the coating layer is 10 to 90% of the total thickness, it easily deforms and adheres to the separator or the like, and a sufficient gas seal is achieved.

  Usually, the metal foil material can be brought into close contact with the separator by pressing at normal temperature (for example, 20 to 35 ° C.). However, in the case of the metal foil material composed of a core material and a coating layer, It is preferable that the temperature is raised to a temperature range lower than the melting temperature of the coating layer) and pressed.

  The material of the metal wire is also not particularly limited, but is preferably made of a metal that is deformed by pressing and is easy to form the gas seal portion 2. As such a metal, the metal and the alloy described as the metal material are preferable. If the metal and the alloy are used, the gas seal by the formed gas seal portion 2 is sufficiently performed, and the fuel gas and the oxidizing gas Leakage is sufficiently prevented. Further, the metal wire is made of Ag, Au, Cu, Ni, or at least one of Ag, Au, Cu and Ni, which is easily deformed by pressing, 0.5 mass% or more, particularly 30 mass% or more, and further 60 mass. % (Usually 80% by mass or less) of the alloy, more preferably 0.5% by mass or more, particularly 30% by mass or more of Ag, Cu, or Ag and Cu excellent in spreadability. Further, it is particularly preferable to be made of an alloy containing 60 mass% (usually 80 mass% or less).

The metal wire can also be a wire made of a core material and a coating layer provided on the surface of the core material. The method for providing the coating layer is not particularly limited, and examples thereof include a method of plating a metal material on the core material and vapor deposition. The core material is not particularly limited as long as the metal wire, particularly the coating layer, can be easily deformed by pressing. When the core material is made of a metal that can be easily deformed, such as Ag, Au, and Cu, the core material may be a solid body or may be a solid body such as a tubular body or a C-shaped cross section. On the other hand, when it is made of a hard metal such as stainless steel, nickel-base alloy, and chromium-base alloy, it may be solid or non-solid, but it is preferably non-solid such as a tubular body.
In addition, in the case of the core material having the C-shaped cross section, the direction of the slit portion at the time of pressing is not particularly limited, and the metal wire is sufficiently deformed in any of the vertical direction, the horizontal direction, and the diagonal direction. be able to.

  The coating layer can be formed of the metal and alloy described as the metal material. These metals and alloys can be easily deformed by pressing, and the formed gas seal portion 2 can sufficiently prevent leakage of fuel gas and oxidizing gas. Further, the coating layer is preferably made of a soft metal such as Ag, Cu and Au, and at least one of Ag, Cu, or Ag and Cu having excellent spreadability is 0.5% by mass or more, particularly 30% by mass. It is particularly preferable to be made of an alloy containing at least 60% and further 60% by mass (usually 80% by mass or less).

  As the metal wire comprising the core material and the coating layer, it is particularly preferable that the core material has a non-solid form such as a tubular body having a circular cross section made of stainless steel, and the coating layer is made of Ag or Cu. With such a metal wire, even when this metal wire is deformed relatively greatly, it can be easily deformed as in the case of a solid body having a circular cross section made of Ag or Cu, and the formed gas The seal part 2 sufficiently prevents leakage of fuel gas and oxidizing gas.

  The cross-sectional shape of the metal wire is not particularly limited, and the cross-sectional shape may be a circle, an ellipse, or a polygon such as a triangle or a quadrangle. This cross-sectional shape is preferably circular or elliptical. The dimension of the metal wire (diameter when it is circular in cross section, and maximum dimension otherwise) is not particularly limited, but can usually be 100 to 1000 μm. Furthermore, when it consists of a core material and a coating layer, it takes into account the cross-sectional shape and dimensions of the groove portion described later provided in the separator, and when the metal wire material is pressed, a sufficient compressive force is applied to the metal wire material. It is preferable that the shape and size be such that a good gas seal is made.

  The metal wire can usually be deformed by pressing at normal temperature (for example, 20 to 35 ° C.), but its melting temperature (in the case of a metal wire consisting of a core wire and a coating layer, in particular, the melting temperature of the coating layer). ) It is preferable that the temperature is raised to a lower temperature range and pressed.

  The ratio of the dimension in the pressing direction to the dimension in the direction orthogonal to the pressing direction (the dimension in the pressing direction / the dimension in the direction orthogonal to the pressing direction) is preferably 0.8 to 1.7. This ratio is more preferably 0.8 to 1.5, particularly 0.8 to 1.2. When the dimension in the pressed direction is not excessively smaller than the dimension in the direction orthogonal to the pressing direction, in particular, the dimension in the pressed direction is the same as or compared with the dimension in the direction orthogonal to the pressing direction. When it is large, a large compressive force can be applied to the metal wire with the same pressing force. Thereby, the metal wire can be easily deformed, the gas seal by the formed gas seal portion 2 is sufficiently performed, and leakage of the fuel gas and the oxidizing gas is prevented.

  The metal wire may be disposed at a predetermined position on the surface of the separator that is not processed at all, or may be disposed in a groove provided at a predetermined position on the surface of the separator. In the case where the metal wire is disposed on the surface that is not processed at all, it is not easy to position, and therefore it is preferable that a groove is provided on the surface of the separator. When a metal wire is used, the groove serves as a positioning means for forming the gas seal portion 2 at a predetermined position. The cross-sectional shape, dimensions, and the like of the groove portion are not particularly limited, and the cross-sectional shape can be a semicircle, a semi-ellipse, a polygon such as a triangle and a quadrangle, and the like. As for the dimensions, the width can be 0.3 to 1.7 mm, particularly 0.5 to 1.5 mm, and further 0.7 to 1.3 mm, and the depth can be 0.1 to 1.0 mm, particularly 0.3. It can be set to 3 to 0.7 mm. The cross-sectional shape and dimensions of the groove are preferably adjusted so that when a metal wire is used and the metal wire is pressed, a sufficient compressive force is applied to the metal wire and a reliable gas seal is achieved.

When the groove portion is provided, the gas seal portion 2 only needs to be formed in a form in which a part of the groove portion is filled with a metal sealing material, and thereby sufficient gas sealing is achieved. The metal sealing material may be filled in the entire groove portion or may overflow from the groove portion, but it is not necessary to do so. The interval between separators to be gas sealed is not particularly limited, but is preferably 50 μm or less, more preferably 30 μm or less, and particularly preferably 10 μm or less (usually 5 μm or more).
When two kinds of separators are stacked, the groove may be provided only in one of the separators (see FIGS. 2 and 3), or may be provided in both (see FIGS. 4 and 5). In order to apply a large compressive force to the metal wire by pressing, the groove is preferably provided only on one of the separators.

  In the solid oxide fuel cell, other seal portions except for the portion gas-sealed by the gas seal portion 2 can be joined by, for example, a metal brazing material or the like to form the joint portion 5 and gas-seal (see FIG. 7, 8, and 12, 13). Furthermore, in order to electrically insulate each single cell, a ceramic frame 4 made of an insulating ceramic is provided at a predetermined portion in the stacking direction to prevent a short circuit as in the examples described later. (See FIGS. 7, 8 and 12, 13). The ceramic frame 4 and the separator laminated with the ceramic frame 4 can also be joined by a metal brazing material or the like to form a joined portion 5 for gas sealing.

The ceramic frame 4 only needs to have insulating properties, and the material thereof is not particularly limited, but MgO, MgAl ₂ O ₄ , ZrO _2, Al ₂ O ₃ , a mixture thereof, and the like are often used.

  The metal brazing material used for brazing is not particularly limited, and Ni-based metal brazing material, Ag-based metal brazing material, and the like can be used. As this metal brazing material, a Ni-based metal brazing material having better heat resistance is preferable. This Ni-based metal brazing material contains Ni and B or P, and when the Ni-based metal brazing material is 100% by mass, the Ni content is 60% by mass or more. it can. 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, the heat resistance can be sufficiently increased.

  The Ni-based metal brazing material may contain B or P in addition to Ni. By containing B or P, the fluidity is improved, the respective members can be sufficiently brought into close contact with each other, and the bonding strength can be further increased. The content of B or P is not particularly limited, but when the Ni-based 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 2-3. It can be 5 mass%. If the content of B is 1 to 5% by mass, the fluidity of the Ni-based metal 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 fluidity of the Ni-based metal brazing material can be sufficiently increased.

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

  An Ag-based metal brazing material can also be used as the metal brazing material. This Ag-based metal brazing material usually contains Pd. When the total of Ag and Pd is 100% by mass, Pd is contained by 2 to 10% by mass, particularly 3 to 7% by mass. If content of Pd is 2-10 mass%, oxidation resistance etc. can be improved and the junction part 5 which has sufficient durability can be formed. Furthermore, the Ag-based metal brazing material flows sufficiently during the joining, and the gas sealability of the joining portion 5 can be improved.

  The Ag-based metal 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 when it is not contained, it has sufficient fluidity and excellent sealing performance is maintained. 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 metal brazing material flows sufficiently and the gas seal of the joint 5 is obtained. Can be improved.

  The Ag-based metal 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. If the Ti content is 0.05 to 10% by mass, it is possible to form the bonding portion 5 having practically sufficient strength even if the bonding atmosphere is an atmosphere having a low oxygen partial pressure.

  When power is generated using a solid oxide fuel cell, a fuel gas is introduced to the fuel electrode side and an oxidizing gas is introduced to the air electrode side. Examples of the fuel gas include hydrogen, hydrocarbon as a hydrogen source (hydrogen is obtained by reforming), a mixed gas of hydrogen and hydrocarbon, and a fuel gas obtained by humidifying these gases through water at a predetermined temperature, The fuel gas etc. which mixed water vapor | steam with this gas are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. Further, the main components are saturated hydrocarbons having 1 to 10, preferably 1 to 7, more preferably 1 to 4 carbon atoms such as methane, ethane, propane, butane and pentane, and unsaturated hydrocarbons such as ethylene and propylene. Those having a saturated hydrocarbon as a main component are more preferable. The fuel gas is preferably hydrogen. 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 oxidizing gas include a mixed gas of oxygen and another gas. The mixed gas may contain about 80% by volume or less of an inert gas such as nitrogen and argon. Of these oxidizing gases, air (containing about 80% by volume of nitrogen) is preferable because it is safe and inexpensive.

Hereinafter, the present invention will be described specifically by way of examples.
Example 1
A solid electrolyte fuel cell 101 (see FIGS. 1 and 6 to 8) includes a solid electrolyte layer 11, a fuel electrode 12 provided on one surface of the solid electrolyte layer 11, and an air electrode 13 provided on the other surface. The bottom member 311 functions as an interconnector when further cells are disposed on the bottom surface of the bottom member 311 [FIGS. 6 to 8. ] And the fuel frame 32 are provided with a gas seal portion 2 made of a metal wire. Further, the gas seal portion 2 made of a metal wire is provided between the interconnector 312 and the air frame 34. Further, in the solid oxide fuel cell 101, the gas seal portion 2 is provided between the second interconnector 312 and the fuel frame 32, and the lid member 313 [see FIGS. When is provided, the lid member 313 functions as an interconnector. ] And the air frame 34.

In the fuel cell, between the interconnector 312 and the fuel frame 32 and between the bottom member 311 and the fuel frame 32 provided with the gas seal portion 2 as described above are the same part in the fuel cell, The space between the lid member 313 and the air frame 34 is the same as the space between the interconnector 312 and the air frame 34. In this way, the gas seal portion 2 is provided between the bottom member, the lid member, and the interconnector, and the respective fuel frame and / or air frame.
Although not shown in FIGS. 1 and 6 to 8, the gas seal portion 2 is formed by pressing the metal wire 21 disposed in the groove portion 341 provided in the air frame 34 or the like. (See FIG. 3).

A solid oxide fuel cell was produced as follows.
(1) Formation of unsintered fuel electrode Nickel oxide (NiO) powder and zirconia powder stabilized by 8 mol% yttria were mixed, and then artificial graphite powder was blended as a pore former, and further mixed . Next, diethylamine as a dispersant and a mixed solvent of toluene and methyl ethyl ketone as an organic solvent were blended and mixed using an alumina pot mill. Next, dibutyl phthalate as a plasticizer and polyvinyl alcohol as a binder were blended and further mixed to prepare a slurry for an unfired fuel electrode. Next, an unfired fuel electrode was formed by the doctor blade method using this slurry.

(2) Formation of unsintered solid electrolyte layer and co-sintering The zirconia powder stabilized with 8 mol% of yttria was mixed with butyl carbitol as a solvent and mixed to prepare a slurry for unsintered solid electrolyte layer. Next, an unfired solid electrolyte layer having the same shape and size as the unburned fuel electrode and a thickness of about 20 μm was formed on one surface of the unburned fuel electrode by screen printing using the slurry. Then, it baked integrally in the air atmosphere.

(3) Formation of unsintered air electrode Slurry for unsintered air electrode by mixing and mixing butyl carbitol as a solvent with La _0.6 Sr _0.4 (Co _0.2 Fe _0.8 ) O ₃ powder. Was prepared. Thereafter, an unfired air electrode having a thickness of about 20 μm was formed at the center of the other surface of the solid electrolyte layer 11 by screen printing using this slurry. Subsequently, it baked in the air atmosphere and the air electrode 13 was formed. In this way, two single cells were produced.

(4) Manufacture of a solid electrolyte fuel cell The two single cells prepared in the above (1) to (3) are laminated through a separator having a gas flow path such as an interconnector or the like, or using this separator. The solid electrode type fuel cell 101 of the fuel electrode support type and the internal manifold type was manufactured.
Hereinafter, a description will be given with reference to FIG. 1 and FIGS.
FIG. 1 is a perspective view schematically showing a bottom member, a lid member, an interconnector, a fuel frame, an air frame, and the like, by disassembling the solid oxide fuel cell 101. FIG. 6 is a perspective view of the appearance of the solid oxide fuel cell 101, FIG. 7 is a schematic view of the AA cross section in FIG. 6, and FIG. 8 is a schematic view of the BB cross section in FIG.
This solid oxide fuel cell 101 is formed by laminating an upper cell and a lower cell each having one single cell.

The lower cell has a nickel felt layer 6 as a current collector disposed on the upper surface of the bottom member 311, a fuel electrode 12 as a substrate, a solid electrolyte layer 11, an air electrode 13, and a platinum mesh layer 7 as a current collector in this order. The upper surface of the platinum mesh layer 7 is in contact with the interconnector 312. Further, a fuel frame 32 joined to the outer peripheral edge of the bottom member 311, a ceramic frame made of a MgO—MgAl ₂ O ₄ sintered body whose lower surface is joined to the solid electrolyte layer 11 and the fuel frame 32 and whose upper surface is an insulating ceramic. 4, the cell support plate 33 is joined to the air frame 34 via 4, and the air frame 34 is joined to the ceramic frame 4 at the lower surface and joined to the outer peripheral edge of the interconnector 312.

  In the lower cell, the fuel frame 32, the cell support plate 33, and the air frame 34 are all formed of SUS430. Further, the fuel frame 32 and the cell support plate 33, the cell support plate 33 and the ceramic frame 4, and the ceramic frame 4 and the air frame 34 are each made of Ni-based metal brazing material, brazed in a vacuum atmosphere, and joined portion 5 Formed. Further, the gas seal portion 2 was formed between the bottom member 311 and the fuel frame 32 using a metal wire made of Ag as described later. Further, the gas seal portion 2 was formed between the air frame 34 and the interconnector 312 using a metal wire made of Ag as described later.

The upper cell includes a nickel felt layer 6 disposed on the upper surface of the interconnector 312, a fuel electrode 12 serving as a substrate, a solid electrolyte layer 11, an air electrode 13, and a platinum mesh layer 7 in this order, and the upper surface of the platinum mesh layer 7. Is in contact with the lid member 313. Further, a fuel frame 32 joined to the outer peripheral edge of the interconnector 312, a ceramic frame made of a MgO—MgAl ₂ O ₄ sintered body whose lower surface is joined to the solid electrolyte layer 11 and the fuel frame 32 and whose upper surface is an insulating ceramic. 4, the cell support plate 33 is joined to the air frame 34 through the bottom surface 4, and the air frame 34 is joined to the ceramic frame 4 at the lower surface and joined to the outer peripheral edge of the lid member 313.

In the upper cell, the fuel frame 32, the cell support plate 33, and the air frame 34 are all formed of SUS430. Further, the third interconnector 313 (lid member) is also formed of SUS430. The fuel frame 32 and the cell support plate 33, the cell support plate 33 and the ceramic frame 4, and the ceramic frame 4 and the air frame 34 are made of Ni-based metal brazing material, brazed in a vacuum atmosphere, and joined 5 Formed. Further, the gas seal portion 2 was formed between the interconnector 312 and the fuel frame 34 using a metal wire made of Ag as described later. Further, the gas seal portion 2 was formed between the air frame 34 and the lid member 313 using a metal wire made of Ag as described later.
The bottom member 311, the interconnector 312 and the lid member 313 are also formed of SUS430.

The gas seal part 2 was formed as follows.
In the lower cell, the position of the upper surface of the bottom member 311 facing the inner peripheral edge of the fuel frame 32 and the opening surfaces of the fuel gas introduction pipe 81, the fuel gas discharge pipe 82, the oxidizing gas introduction pipe 83, and the oxidizing gas discharge pipe 84. A groove with a rectangular cross section having a width of 1 mm and a depth of 0.5 mm was previously provided around the periphery, and an Ag wire having a diameter of 0.6 mm was disposed in the groove. In addition, a width of 1 mm and a depth of 0. A groove portion having a rectangular cross section of 5 mm was provided, and an Ag wire rod having a diameter of 0.6 mm was disposed in the groove portion.

  Further, in the upper cell, the position of the upper surface of the interconnector 312 facing the inner peripheral edge of the fuel frame 32 and the openings of the fuel gas introduction pipe 81, the fuel gas discharge pipe 82, the oxidizing gas introduction pipe 83, and the oxidizing gas discharge pipe 84. A groove with a rectangular cross section having a width of 1 mm and a depth of 0.5 mm was previously provided around the surface, and an Ag wire having a diameter of 0.6 mm was disposed in the groove. In addition, the inner periphery of the upper surface of the air frame 34 and the periphery of the opening surfaces of the fuel gas introduction pipe 81, the fuel gas discharge pipe 82, the oxidizing gas introduction pipe 83, and the oxidizing gas discharge pipe 84 have a width of 1 mm and a depth of 0. A groove portion having a rectangular cross section of 5 mm was provided, and an Ag wire rod having a diameter of 0.6 mm was disposed in the groove portion.

  After that, the lower cell laminate in which the fuel frame 32 to the air frame 34 were integrally fixed by brazing was arranged so that the fuel frame 32 was placed on the upper surface of the bottom member 311. Next, the interconnector 312 was disposed on the upper surface of the air frame 34. Thereafter, a stack for the upper cell in which the fuel frame 32 to the air frame 34 are stacked is arranged so that the fuel frame 32 is placed on the upper surface of the interconnector 312. Next, a lid member 313 was disposed on the upper surface of the air frame 34. After that, the entire laminate is sandwiched from above and below by pressing plates, and tightened by nuts fitted to the bolts attached to the four corners of the pressing plates, so that a pressing force of 15 MPa is applied in the stacking direction to compress the Ag wire. While deforming, the gas seal part 2 was formed, and the whole from the bottom member 311 to the lid member 313 was fixed integrally, and the solid oxide fuel cell 101 was manufactured.

(5) Fuel gas introduction pipe or exhaust pipe, and oxidizing gas introduction pipe or exhaust pipe On the lower cell side, the space formed between the bottom member 311, the cell support plate 33 and the single cell has no fuel in the lower cell. A fuel gas introduction pipe 81 for introducing fuel gas into the pole 12 is opened (see FIG. 7). A fuel gas discharge pipe 82 for discharging fuel gas from this space is opened on the diagonal side of the opening of the fuel gas introduction pipe 81 in this space (see FIG. 7). Further, in the space formed between the cell support plate 33 and the single cell and the interconnector 312, an oxidizing gas introduction pipe 83 for introducing an oxidizing gas into the air electrode 13 of the lower cell is opened (see FIG. 8). Further, an oxidant gas discharge pipe 84 for discharging the oxidant gas from the space is opened on the diagonal side of the opening of the oxidant gas introduction pipe 83 in this space (see FIG. 8).

Further, on the upper cell side of the solid oxide fuel cell 101, a space formed between the interconnector 312 and the cell support plate 33 and the single cell is used for introducing fuel gas into the fuel electrode 12 of the upper cell. The fuel gas introduction pipe 81 is opened (see FIG. 7). Furthermore, a fuel gas discharge pipe 82 for discharging fuel gas from this space is opened on the diagonal side of the opening of the fuel gas introduction pipe 81 in this space (see FIG. 7). Further, an oxidizing gas introduction pipe 83 for introducing an oxidizing gas into the air electrode 13 of the upper cell is opened in the space formed between the cell support plate 33 and the single cell and the lid member 313 (FIG. 8). Further, an oxidant gas discharge pipe 84 for discharging the oxidant gas from this space is opened on the diagonal side of the opening of the oxidant gas introduction pipe 83 in this space (see FIG. 8).
In this fuel cell, when another cell is further stacked on the lower surface of the lower cell, the bottom member 311 functions as an interconnector. Further, when another cell is further laminated on the upper surface of the upper cell, the lid member 313 functions as an interconnector.

  Each pipe for introducing or discharging fuel gas or oxidant gas to each of the lower cell and the upper cell is required for the bottom member, lid member, interconnector, cell support plate, fuel frame, air frame and ceramic frame. Each gas flow path provided at each location is connected and integrally formed. As a whole, a side pipe is attached to the main pipe, and a fuel gas or an oxidizing gas is attached to the lower cell and the upper cell. Are simultaneously introduced and discharged. Further, in this embodiment, the fuel gas introduction pipe and the fuel gas discharge pipe, and the oxidant gas introduction pipe and the oxidant gas discharge pipe are attached at positions where the fuel gas and the oxidant gas circulate in a diagonal direction. Yes. Thereby, the fuel electrode and fuel gas of each of a lower cell and an upper cell, and an air electrode and oxidizing gas can each be made to contact efficiently.

(6) Extraction of electric power from the fuel cell In the solid oxide fuel cell 101, the air electrode 13 of the lower cell is electrically connected to the interconnector 312 via the platinum mesh layer 7 as a current collector. The interconnector 312 is electrically connected to the fuel electrode 12 of the upper cell through the nickel felt layer 6 that is a current collector. Thus, the lower cell and the upper cell are connected in series. Further, the temperature of the fuel cell is raised to a predetermined operating temperature, a fuel gas such as hydrogen is introduced into the fuel gas introduction pipe 81 and brought into contact with the fuel electrode 12, and an oxidizing gas such as air is introduced into the oxidizing gas introduction pipe 83. By making contact with the air electrode 13, an electromotive force is generated between the fuel electrode 12 and the air electrode 13, and this power can be taken out to function as a power generator. The electric power is taken out from the bottom member 311 on the fuel electrode side, and taken out from the lid member 313 on the air electrode side, and the electric power of the entire fuel cell can be taken out between the lid member and the bottom member.

(7) Evaluation of Open Circuit Voltage and Fuel Utilization Rate Hydrogen gas containing 3% by mass of water is introduced as a fuel gas from the fuel gas introduction pipe 81 of the solid oxide fuel cell 101, and air is supplied from the oxidation gas introduction pipe 83. The open circuit voltage of each of the lower cell and the upper cell was measured. As a result, the open circuit voltage of the lower cell is 1.12 V, and the open circuit voltage of the upper cell is 1.10 V, both of which are close to the theoretical values, and the gas sealing is sufficiently performed including the portion sealed with the Ag wire. I understood that. Moreover, the flow rate of hydrogen was changed while taking out a current of 0.2 A / cm ² , and the voltage of each of the lower cell and the upper cell at that time was measured to evaluate the fuel utilization rate. The results are shown in FIG. 9 (Δ is the voltage of the lower cell, and ◇ is the voltage of the upper cell). According to FIG. 9, it was possible to evaluate at a utilization rate exceeding 90%. This means that the fuel gas and the oxidizing gas do not leak and these gases are not mixed with each other, and it has been found that the gas sealing performance is good.

Example 2
The solid oxide fuel cell 102 (see FIGS. 11 to 13) has two single cells having the same configuration as that of the first embodiment, and a bottom member 311 [the bottom surface of the bottom member 311 in FIGS. When the cells are further arranged, the bottom member 311 functions as an interconnector. ] And the fuel frame 32 are provided with the gas seal portion 2 made of the metal foil material 22 (see FIG. 10). Further, the gas seal part 2 made of the same metal foil material is provided between the second interconnector 312 and the air frame 34.

  Further, in this solid oxide fuel cell 102, the gas seal portion 2 includes a cell disposed between the interconnector 312 and the fuel frame 32, and a lid member 313 (see FIGS. 11 to 13, further cells are disposed on the upper surface of the lid member 313. When provided, the lid member 313 functions as an interconnector. ] And the air frame 34 using the same metal foil material as described above. In this way, the gas seal portion 2 is provided between the bottom member, the lid member, and the interconnector, and the respective fuel frame and / or air frame.

A solid oxide fuel cell was produced as follows.
(1) Production of single cell Two single cells were produced in the same manner as (1) to (3) in the production of the solid oxide fuel cell 101 in Example 1.

(2) Manufacture of a solid electrolyte fuel cell The fuel cell support type in which the two single cells prepared in (1) above are stacked through or using a separator having a gas flow path. An internal manifold type solid oxide fuel cell 102 was manufactured.
Hereinafter, a description will be given with reference to FIGS.
FIG. 10 is a plan view of a metal seal material made of a metal foil material used for forming the gas seal portion 2. This metal foil material 22 is obtained by applying 50 μm thick Ag plating (coating layer) to the front and back surfaces of a stainless steel frame (core material) made of SUS430 having a thickness of 50 μm, and the total thickness is 150 μm. The metal foil material 22 is provided with a central opening 221 for allowing a fuel gas or an oxidizing gas to flow therethrough and two fuel gas or oxidizing gas isolating openings 222. In addition, a positioning outer peripheral portion 223 is provided for accurately positioning relative to the interconnector. The positioning outer peripheral portion 223 has an outer periphery that overlaps with the outer periphery of the interconnector, and can position the separator accurately and easily.

FIG. 11 is a perspective view schematically showing a separator (bottom member, lid member, interconnector, fuel frame and air frame) having a gas flow path, a metal foil material, etc., by disassembling the solid oxide fuel cell 202. . Further, FIG. 12 is a schematic view showing a cross section in which the fuel gas introduction pipe 81 and the fuel gas discharge pipe 82 are formed in FIG. FIG. 13 is a schematic view of a cross section in which the oxidizing gas introduction pipe 83 and the oxidizing gas discharge pipe 84 are formed in FIG.
The solid oxide fuel cell 102 is formed by laminating an upper cell and a lower cell each having one single cell. The structure of each of the upper cell and the lower cell is the same as that of the solid oxide fuel cell 101 of the first embodiment. Further, the materials of the fuel frame 32, the cell support plate 33, and the air frame 34, and the materials of the bottom member 311, the interconnector 312 and the lid member 313 included in each of the upper cell and the lower cell are the solid electrolyte of the first embodiment. This is the same as in the case of the fuel cell 101.

  Further, as in the case of the solid oxide fuel cell 101 of the first embodiment, the fuel frame 32 and the cell support plate 33, the cell support plate 33 and the ceramic frame 4, and the ceramic frame 4 and the air frame 34 are respectively connected to the Ni-based metal braze. The joint part 5 was formed by using a material and brazing in a vacuum atmosphere. Further, in the solid oxide fuel cell 102, the bottom member 311 and the lower cell fuel frame 32, the lower cell air frame 34 and the interconnector 312, the interconnector 312 and the upper cell fuel frame 32, and the like. And between the air frame 34 of the upper cell and the lid member 313 were gas-sealed using the metal foil material 22 described in the above (2) to form the gas seal portion 2.

  In the same manner as in Example 1, the gas seal portion 2 includes a bottom member 311, a metal foil material 22 placed on the top surface of the bottom member 311, a laminated body for the lower cell, and a laminated body for the lower cell. The metal foil material 22 placed on the upper surface of the body, the interconnector 312, the metal foil material 22 placed on the upper surface of the interconnector 312, the laminate for the upper cell, and the laminate for the upper cell The metal foil material 22 placed on the upper surface of the body and the lid member 313 were laminated, and then formed by applying a pressing force in the same manner. In this way, the entire structure from the bottom member 311 to the lid member 313 was fixed integrally, and the solid oxide fuel cell 102 was manufactured.

(3) Fuel gas introduction pipe or fuel gas discharge pipe, and oxidizing gas introduction pipe or oxidizing gas discharge pipe In the solid oxide fuel cell 102, in the lower cell, between the bottom member 311 and the cell support plate 33 and the single cell. In this space, a fuel gas introduction flow path for introducing fuel gas into the fuel electrode 12 of the lower cell is formed. In this flow path, the upper cell, the interconnector 312, the cell support plate 33, and the single cell are formed. A fuel gas introduction pipe 81 is provided so that a flow path for introducing fuel gas into the fuel electrode 12 of the upper cell formed in the space between the two becomes a continuous flow path. . Further, on the side of each space facing the flow path, a fuel gas discharge pipe 82 for discharging fuel gas from these spaces is connected to the flow path in the lower cell and the flow path in the upper cell. It is provided so that it may become a flow path.

  Further, in the lower cell, an oxidizing gas introduction channel for introducing an oxidizing gas into the air electrode 13 of the lower cell is formed in a space between the cell support plate 33 and the single cell and the interconnector 312. In the upper channel, the oxidizing gas introduction channel for introducing the oxidizing gas into the air electrode 13 of the upper cell, which is formed in the space between the cell support plate 33 and the single cell and the lid member 313. Are provided with an oxidizing gas introduction pipe 83 so as to form a continuous flow path. In addition, an oxidizing gas discharge pipe 84 for discharging the oxidizing gas from these spaces is provided on the side facing each flow path of these spaces, and the flow path in the lower cell and the flow path in the upper cell are continuous. It is provided so that it may become a flow path.

  Each flow path for introducing or discharging fuel gas or oxidant gas to each of the lower cell and the upper cell includes a bottom member, a lid member, an interconnector, a cell support plate, a fuel frame, an air frame, and a ceramic frame. Each gas flow path provided at a required location is connected and integrally formed, and fuel gas or oxidizing gas is simultaneously introduced into and discharged from the lower cell and the upper cell. Further, the fuel gas is introduced from the opening of the fuel gas introduction pipe 81 provided in the bottom member 311 and discharged from the opening of the fuel gas discharge pipe 82 provided in the diagonal direction (see FIG. 12). Further, the oxidizing gas is introduced from the opening of the oxidizing gas introduction pipe 83 provided in the lid member 313, and is discharged from the opening of the oxidizing gas discharge pipe 84 provided in the diagonal direction (see FIG. 13).

(4) Extraction of electric power from fuel cell and evaluation of open circuit voltage and fuel utilization rate In the solid oxide fuel cell 102, the lid member and the bottom portion are the same as in the case of the solid oxide fuel cell 101 of Example 1. The power of the entire fuel cell can be taken out from the material. Similarly, when the open circuit voltages of the lower cell and the upper cell were measured, the open circuit voltage of the lower cell was 1.11 V, and the open circuit voltage of the upper cell was 1.10 V, both of which were close to theoretical values. It was found that gas sealing was sufficiently performed including the part sealed with the metal foil material. Further, the fuel utilization rate evaluated in the same manner is shown in FIG. 14 (Δ is the voltage of the lower cell, and ◇ is the voltage of the upper cell). According to FIG. 14, it was possible to evaluate at a utilization rate exceeding 90%. This means that the fuel gas and the oxidizing gas do not leak and these gases are not mixed with each other, and it has been found that the gas sealing performance is good.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention depending on the purpose, application, and the like. For example, the planar shape of the cell can be a rectangle, a circle, an ellipse, or the like, and a solid oxide fuel cell having a similar planar shape can be obtained. In addition, the fuel gas introduction pipe and the fuel gas discharge pipe, and the oxidant gas introduction pipe and the oxidant gas discharge pipe can each be formed in a slit shape instead of a pipe, and the introduction slit and the discharge slit are opposed to each other with a single cell interposed therebetween. By disposing at the positions, the fuel electrode of each of the lower cell and the upper cell and the fuel gas, and the air electrode and the oxidizing gas can be efficiently contacted.

  In this fuel cell, usually, two or more structures (ie, cells) having a fuel frame 32, a cell support plate 33, an air frame 34, and a single cell are connected via an interconnector (the above-described embodiment). 1 and 2, two cells, a lower cell and an upper cell). The number of the structures can be set according to the purpose, application, etc., and is not particularly limited, but can be 10 to 250. In a fuel cell having two or more structures, each cell is stacked and connected via an interconnector. When n structures are stacked and connected, the number of interconnectors is n. The bottom member is laminated on the lower surface of the first cell, and the lid member is laminated on the upper surface of the (n + 1) th cell.

  Further, the metal wire is provided around the inner peripheral edges of the fuel frame 32 and the air frame 34, and around the opening surfaces of the fuel gas introduction pipe 81, the fuel gas discharge pipe 82, the oxidation gas introduction pipe 83, and the oxidation gas discharge pipe 84. For example, in FIG. 1 illustrating the case of Example 1, the metal wire 21 disposed on the other surface side of the lower air frame 34 in FIG. The inner peripheral edge is integrally formed with the surroundings of the opening surfaces of the oxidizing gas introduction pipe 83 and the oxidizing gas discharge pipe 84, and the surroundings of the opening faces of the fuel gas introduction pipe 81 and the fuel gas discharge pipe 82 are separate. is there. The metal wire disposed on the inner periphery of the fuel frame 32 and the air frame 34, and the periphery of the opening surfaces of the fuel gas introduction pipe 81, the fuel gas discharge pipe 82, the oxidizing gas introduction pipe 83, and the oxidizing gas discharge pipe 84 It may be a separate body from the metal wire to be formed, or may be a continuous and integral one.

  Further, the metal foil material 22 is disposed on the surface of a separator such as an interconnector so as to surround the single cell, and each of the fuel gas introduction pipe, the fuel gas discharge pipe, the oxidizing gas introduction pipe, and the oxidizing gas discharge pipe is provided. It is arrange | positioned around the part which is opening. In the second embodiment, the metal foil material 22 disposed at each position is an integral one, but the metal foil material is integrated with a plurality of separate metal foil materials at their respective end portions in contact with each other. It may be arranged in this way. Furthermore, in Example 2, the integral metal foil material 22 is disposed so as to surround the single cell, and is disposed around the portion where each flow path is open, but surrounds the single cell. The metal foil material arranged in this manner and the metal foil material arranged around the portion where each flow path is open may be separate. This metal foil material is preferably an integral one as in Example 2 from the viewpoint of ease of handling and ease of disposition at a predetermined location.

  The gas seal portion 2 is provided between the bottom member 311 and the fuel frame 32, and the gas seal portion 2 leaks fuel gas from the fuel gas introduction pipe 81 and the fuel gas discharge pipe 82, and the fuel frame 32. Leakage of fuel gas from the internal space to the outside is prevented. Further, the gas seal portion 2 is provided between the interconnector 312 and the air frame 34, etc., and the gas seal portion 2 causes leakage of oxidizing gas from the oxidizing gas introduction pipe 83 and the oxidizing gas discharge pipe 84 and air. Leakage of oxidizing gas from the internal space of the frame 34 to the outside is prevented. In the first and second embodiments, the gas seal portion 2 is provided both between the bottom member and the interconnector and the fuel frame, and between the interconnector and the lid member and the air frame. It can also be provided on one side. As in the first and second embodiments, the gas seal portion 2 is preferably provided between the bottom member and the interconnector and the fuel frame, and between the lid member and the interconnector and the air frame.

  The gas seal portion 2 is formed by pressing a metal seal material made of a metal layer 3122 (a) (see FIGS. 17 and 19) disposed on the surface of the linear protrusion 3122 provided on at least one surface of the separator. (See FIGS. 18 and 20). Further, the surface of the separator that is not provided with the linear convex portion may be a flat plate (see FIGS. 19 and 20) or may be provided with a groove portion 341 (see FIG. 17). 18), it is not necessary to provide a groove. In the case where the groove portion 341 is provided, the gas seal portion 2 may be formed in a form in which the deformed metal layer is brought into close contact with the bottom portion of the groove portion (see FIG. 18). The deformed metal layer may be filled in the entire groove portion or may overflow from the groove portion, but this is not particularly necessary.

  The cross-sectional shape, dimensions, and the like of the linear protrusions are not particularly limited, and the cross-sectional shape can be a semicircle, a semi-elliptical shape, a polygon such as a triangle and a quadrangle, and the like. This cross-sectional shape is preferably semicircular or semielliptical.

  The metal layer can be formed by coating the surface of the linear convex portion by a method such as plating, screen printing, and vapor deposition. Moreover, it can also form by arrange | positioning metal foil on the surface of a linear convex part. The material of the metal layer is not particularly limited, but is preferably made of a metal that is deformed by pressing and is easy to form the gas seal portion 2. Examples of such metals include the metals and alloys described above as metal materials. If these metals or alloys are used, gas sealing by the formed gas seal portion 2 is sufficiently performed, and leakage of fuel gas and oxidizing gas is prevented. Furthermore, the metal layer is made of Ag, Cu, or Ag and Cu having excellent spreadability, 0.5% by mass or more, particularly 30% by mass or more, and further 60% by mass (usually 80% by mass or less). It is particularly preferable that the alloy is contained.

  Usually, the metal layer can be deformed by pressing at normal temperature (for example, 20 to 35 ° C.), but it is preferable that the metal layer is heated to a temperature range lower than its melting temperature and pressed.

  The linear protrusion and the metal layer are formed on the surface of the separator so as to surround the single cell. Further, it is formed around the opening surface of each of the fuel gas introduction pipe, the fuel gas discharge pipe, the oxidation gas introduction pipe, and the oxidation gas discharge pipe. The linear protrusions and the metal layer formed at each position are formed as a continuous and integral one. Further, it is formed around the linear protrusions and the metal layer formed so as to surround the single cell, and around the opening surfaces of the fuel gas introduction pipe, the fuel gas discharge pipe, the oxidizing gas introduction pipe, and the oxidizing gas discharge pipe. The linear protrusions and the metal layer may be separate from each other, or may be a continuous integral body.

  Furthermore, this fuel cell can also be made into a structure which does not have a cell support plate. For example, a fuel electrode having a smaller area than the solid electrolyte layer is provided on one surface of the solid electrolyte layer, an air electrode having a smaller area than the solid electrolyte layer is provided on the other surface of the solid electrolyte layer, and a fuel gas is provided in the solid electrolyte layer. Or it can also be set as the structure which formed the opening part for distribute | circulating oxidizing gas. In this case, a separator having a gas flow path is laminated as an interconnector on one surface and the other surface of the solid electrolyte layer, and a planar metal foil material as shown in FIG. 15 is interposed between the separator and one surface of the solid electrolyte layer. A metal sealing material made of a planar metal foil material as shown in FIG. 16 is disposed between the separator and the other surface of the solid electrolyte layer, and then each single cell is laminated. And it can be set as a fuel cell. In this structure, if necessary, a fuel frame and an air frame can be interposed between the separator and the solid electrolyte layer. Furthermore, nickel felt, platinum mesh, or the like may be interposed as a current collector between the separator, the fuel electrode, and the air electrode, so that adjacent single cells can be more reliably connected electrically.

It is a perspective view which decomposes | disassembles the solid oxide form fuel cell of Example 1, and shows an interconnector etc. typically. It is explanatory drawing which shows typically the cross section of the groove part provided in the metal member, and the metal wire arrange | positioned in this groove part. It is explanatory drawing which shows typically the state by which the metal wire of FIG. 2 was pressed and the gas seal part was formed with the metal sealing material. It is explanatory drawing which shows typically the state by which the groove part was provided in all the metal members to be sealed, and the metal wire was arrange | positioned in this groove part. It is explanatory drawing which shows typically the state by which the metal wire of FIG. 4 was pressed and the gas seal part was formed with the metal sealing material. 1 is a perspective view showing an appearance of a solid oxide fuel cell of Example 1. 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. 2 is a graph showing the correlation between the fuel utilization rate and the output voltage when the solid oxide fuel cell of Example 1 is operated. It is a top view which shows an example of the metal foil material which is a metal foil material, and has a planar shape which can be positioned relatively with an interconnector etc. It is a perspective view which decomposes | disassembles the solid oxide form fuel cell of Example 2 using the metal foil material shown in FIG. 10 as a metal sealing material, and shows an interconnector etc. typically. It is the schematic diagram which looked at the cross section in which the fuel gas introduction pipe | tube and the fuel gas discharge pipe | tube are formed in the solid oxide fuel cell of FIG. It is the schematic diagram which looked at the cross section in which the oxidizing gas introduction pipe | tube and the oxidizing gas discharge pipe | tube are formed in the solid oxide fuel cell of FIG. It is a graph which shows the correlation of the fuel utilization rate at the time of making the solid oxide fuel cell operation | movement of Example 2 operate | move, and an output voltage. It is a top view which shows the other example of the metal foil material which a metal sealing material is a metal foil material, and has a planar shape which can perform relative positioning with an interconnector etc. It is a top view which shows the further another example of the metal foil material which has a planar shape in which a metal sealing material is a metal foil material and can be positioned relatively with an interconnector or the like. It is explanatory drawing which shows typically the cross section of the linear convex part provided in one metal member, the metal layer coat | covered by this linear convex part, and the groove part provided in the other metal member. It is explanatory drawing which shows typically the state by which the metal layer of FIG. 17 was pressed and the gas seal part was formed with the metal sealing material. It is explanatory drawing which shows typically the cross section of the linear convex part provided in one metal member, the metal layer coat | covered by this linear convex part, and the other metal member. It is explanatory drawing which shows typically the state by which the metal layer of FIG. 19 was pressed and the gas seal part was formed with the metal sealing material.

Explanation of symbols

  101, 102; solid electrolyte fuel cell, 11; solid electrolyte layer, 12; fuel electrode, 13; air electrode, 2; gas seal part, 21; metal wire, 22; metal foil material, 221; 222; opening for separating fuel gas or oxidizing gas, 223; outer periphery for positioning, 2241; opening for circulating fuel gas, 2242; opening for separating fuel gas, 2251; opening for circulating oxygen gas, 2252; oxidizing gas Isolation opening, 226; positioning claw, 311; bottom member, 312; interconnector, 3121; groove provided in the interconnector, 3122; linear protrusion provided in the interconnector, 3122 (a); Metal layer covering the linear convex portion, 313; lid member, 32; fuel frame, 33; cell support plate, 34; air frame, 341; groove provided in the air frame 4; ceramic frame, 5; junction 6; nickel felt layer, 7; platinum mesh layer, 81; fuel gas inlet, 82; fuel gas exhaust pipe, 83; oxidizing gas inlet, 84; oxidant gas exhaust pipe.

Claims (8)

A plurality of single cells having a solid electrolyte layer, a fuel electrode provided on one surface of the solid electrolyte layer, and an air electrode provided on the other surface of the solid electrolyte layer;
A separator provided between the single cells;
A solid oxide fuel cell comprising: a gas seal portion made of a metal seal material disposed on at least one surface of a separator having the gas flow path. 2. The solid electrolyte fuel cell according to claim 1, wherein the metal sealing material is a metal foil material. 2. The solid oxide fuel cell according to claim 1, wherein the metal sealing material is a metal wire. The solid oxide fuel cell according to any one of claims 1 to 3, wherein a groove is formed in the separator. The metal sealing material is an alloy containing 0.5% by mass or more of Ag, Au, Cu, Ni, Pt or at least one of Ag, Au, Cu, Ni, and Pt. The solid oxide fuel cell of any one of them. The metal sealing material includes a core material and a coating layer provided on the surface of the core material, and the coating layer includes Ag, Au, Cu, Ni, Pt, or Ag, Au, Cu, Ni, and Pt. The solid oxide fuel cell according to any one of claims 1 to 5, comprising an alloy containing 0.5% by mass or more of at least one of the above. The solid electrolyte fuel cell according to claim 6, wherein the core material is a tubular body or a C-shaped body in cross section. The solid oxide fuel cell according to claim 1, wherein the metal sealing material is positioned by positioning means.

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