JP5748584B2 - Conductor and solid oxide fuel cell, cell stack, fuel cell - Google Patents

Description

  The present invention relates to a conductor, a solid oxide fuel cell, a cell stack, and a fuel cell.

  Solid oxide fuel cells have high power generation efficiency because of their high operating temperature, and are expected as a third generation power generation system. In a solid oxide fuel cell constituting the solid oxide fuel cell (hereinafter sometimes simply referred to as a fuel cell), an oxygen electrode and a fuel electrode are provided so as to sandwich a solid electrolyte.

Conventionally, LaMnO ₃ -based materials and LaSrCoFeO ₃ -based materials are known as oxygen electrode materials, but materials having good conductivity at higher temperatures are required. Moreover, in order to electrically connect the fuel cells, a conductive bonding material is used, and this conductive bonding material also requires a material having good conductivity at high temperatures.

For example, in recent years, as an oxygen electrode _{material, Ln 1-y A y Ni} 1-x Fe x O 3 based material (Ln is one or any La, Pr, Nd, of Sm, or La, Pr, Nd, Sm And two or more elements selected from among them, and A is one of Sr, Ba and Ca, or two or more elements selected from Sr, Ba and Ca) (See Patent Document 1).

  Moreover, what consists of a perovskite type oxide containing La, Sr, Co, and Fe is known as an electrically conductive joining material for electrically joining solid oxide fuel cells (see Patent Document 2). .

JP 2002-151091 A JP 2005-339904 A

However, the _{Ln 1-y A y Ni 1} -x Fe x O 3 based material and Patent Document 1 is used as the oxygen electrode material, Patent Document 2 La to be used as a conductive bonding material, Sr, Co and Fe Even a material made of a perovskite complex oxide containing bismuth has a problem that the electrical conductivity at high temperature is still low.

  An object of the present invention is to provide a conductor, a solid oxide fuel cell, a cell stack, and a fuel cell having high conductivity at high temperatures.

Conductor of the present invention, when expressed the composition formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, wherein x is 0.5 to 0.6, wherein y is 0. It consists of a perovskite complex oxide satisfying 01 to 0.1 and the z satisfying 0.95 to 1.05.

  The solid oxide fuel cell of the present invention is characterized in that an oxygen electrode is provided on one side of the solid electrolyte and a fuel electrode is provided on the other side, and the oxygen electrode is made of the above-mentioned conductor.

  Furthermore, the cell stack of the present invention includes a plurality of solid oxide fuel cells each having an oxygen electrode on one side and a fuel electrode on the other side of the solid electrolyte, and a plurality of the solid oxide fuel cells. And a conductive bonding material for connecting to the conductive material, wherein the conductive bonding material is made of the above-mentioned conductor.

  Furthermore, the fuel cell of the present invention includes a plurality of the solid oxide fuel cells as described above housed in a storage container, and the plurality of solid oxide fuel cells are electrically connected. It is characterized by. The fuel cell of the present invention is characterized in that the cell stack is accommodated in a storage container.

  In the conductor of the present invention, the conductivity in the high temperature region can be increased. When this conductor is used as the oxygen electrode of the solid oxide fuel cell, the conductivity in the high temperature region of the oxygen electrode is improved. Can be increased. In addition, the conductor of the present invention is used as a conductive bonding material for electrically connecting a plurality of solid oxide fuel cells, and a cell stack is formed so that the solid oxide fuel cells are connected. The electric resistance can be reduced, and the power generation performance in the cell stack can be improved. Therefore, in the fuel cell using the solid oxide fuel cell or cell stack of the present invention, the power generation performance can be improved.

It is a schematic diagram which shows a fuel cell. It is a figure which shows the X-ray-diffraction measurement result of a conductor. FIG. 2 shows a cell stack device, in which (a) is a side view schematically showing the cell stack device, and (b) is an enlarged cross-sectional view showing a part of (a). 3 shows the fuel cell shown in FIG. 3, in which (a) is a cross-sectional view, and (b) is a side view of the state where the interconnector is omitted, as viewed from the interconnector side. FIG. 4 is an excerpt of the current collecting member shown in FIG. 3, where (a) is a perspective view and (b) is a cross-sectional view taken along line BB in (a). The state which electrically connected a pair of fuel cell by the current collection member is shown, (a) is a cross-sectional view, (b) is the longitudinal cross-sectional view along CC line of (a). is there. It is an external appearance perspective view which decomposes | disassembles and shows the fuel cell module formed by accommodating the cell stack apparatus shown in FIG. 1 in a storage container. It is a perspective view which shows the fuel cell apparatus formed by accommodating the fuel cell module shown in FIG. 7 in an exterior case. It is a graph which shows the temperature characteristic of electrical conductivity.

  Hereinafter, the case where the conductor of this embodiment is used as an oxygen electrode of a fuel cell will be described. FIG. 1 is a schematic diagram showing a fuel cell, which is configured by forming an oxygen electrode 3 on one side (upper surface) and a fuel electrode 5 on the other side (lower surface) of a plate-shaped solid electrolyte 1.

When the oxygen electrode 3 represents the composition formula based on the molar ratio as La (Ni _x Cu _y Fe _1-xy ) _z O ₃ , x is 0.5 to 0.6, and y is 0.01 to 0.00. 1, z is composed of a conductor made of conductive ceramics satisfying 0.95 to 1.05.

_X representing the amount of Ni in the B site (Ni _x Cu _y Fe _1-xy ) when the compositional formula based on the molar ratio is expressed as La (Ni _x Cu _y Fe _1-xy ) _z O ₃ 0.5 to 0.6 because the electrical conductivity can be kept high even at a high temperature in this range. When x is smaller than 0.5, the electrical conductivity decreases, and 0.6 This is because the electrical conductivity is lowered even when it is larger than the range.

  Further, the y indicating the amount of Cu in the B site is set to 0.01 to 0.1. When y is smaller than 0.01, the effect of improving the conductivity by adding Cu is low. This is because the second phase due to the Cu compound precipitates and the conductivity decreases. In particular, y is preferably 0.02 to 0.1 and more preferably 0.04 to 0.07 from the viewpoint of precipitation of a stable crystal phase exhibiting high conductivity.

  Furthermore, z indicating the A / B ratio was set to 0.95 to 1.05 because when z is smaller than 0.95, the second phase having lower conductivity than the main phase caused by La This is because if it is precipitated and is larger than 1.05, the second phase resulting from the Cu compound is precipitated. In particular, z is preferably 0.97 to 1.03 from the viewpoint of a stable crystal phase exhibiting high conductivity in a high temperature range.

The oxygen electrode 3 contains La at the A site, Ni, Cu, and Fe at the B site, and is composed of a perovskite complex oxide represented by the general formula ABO _3. perovskite type crystal phase represented by _{la (Ni x Cu y Fe 1} -x-y) z O 3 the one that the main phase, it is desirable that the average crystal grain size is 3 to 20 [mu] m, in particular 5~15μm . This is because when the average crystal grain size is 3 to 20 μm, the strength of the oxygen electrode 3 can be maintained high, and the gas permeability of the oxygen electrode 3 can be maintained high. The open porosity of the oxygen electrode 3 is 20 to 45%, particularly 30 to 40%. The average pore diameter is excellent in gas permeability in the range of 1.0 to 5.0 μm.

In FIG. 2, the X-ray-diffraction measurement result of the conductor which comprises the oxygen electrode 3 is shown. From FIG. 2, it can be seen that the conductor of this embodiment has a perovskite crystal phase as a main phase and substantially no heterogeneous phase is generated. Incidentally, the perovskite type crystal phase constituting the oxygen electrode 3 is, when representing the formula by molar ratio _La as _{(Ni x Cu y Fe 1-} x-y) z O 3, x is 0.5 to 0.6 , Y satisfies 0.01 to 0.1 and z satisfies 0.95 to 1.05, the crystal phase is identified by X-ray diffraction measurement, and the conductor has a perovskite crystal phase as the main phase. After confirming that almost no heterogeneous phase is generated, the air electrode 3 is pulverized, and this can be confirmed by elemental analysis by ICP emission spectroscopic analysis.

The conductive material constituting the oxygen electrode _{3, La (Ni x Cu y Fe} 1-x-y) z O perovskite type crystal phase represented by ₃ was used as a main phase, substantially the perovskite type crystal phase In some cases, however, there are very few peaks of other crystal phases such as NiO and La ₄ Ni ₃ O ₁₀ by X-ray diffraction measurement. Therefore, it is substantially composed of a perovskite type crystal phase. In the X-ray diffraction measurement results, other crystal phases such as NiO and La ₄ Ni ₃ O ₁₀ are main peaks of the main phase having 2θ around 32 °. It means 5% or less with respect to the peak intensity.

As the solid electrolyte 1 of the fuel cell, in addition to rare earth element oxides such as Y ₂ O ₃ , CeO ₂ and Yb ₂ O ₃ , ZrO ₂ stabilized by a known stabilizer such as CaO and MgO is used. The thermal expansion coefficient is about 9 to 12 × 10 ⁻⁶ / ° C. The solid electrolyte 1 may be a solid electrolyte made of another oxide such as a lanthanum gallate material.

As the fuel electrode 5, a known fuel electrode material can be used. For example, the fuel electrode 5 is mainly composed of Ni, and particularly contains 30 to 80% by mass of Ni, and the balance is stabilized ZrO ₂ (Y It is desirable to be made of a porous cermet material comprising a stabilizer such as ₂ O ₃ .

  In addition, the structure of the fuel battery cell may be a cylindrical type or a hollow flat plate type to be described later, in addition to a flat plate formed by laminating a plate-like air electrode, a solid electrolyte, and a fuel electrode.

Next, a method for manufacturing a fuel cell will be described. First, when representing the formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, x is 0.5 to 0.6, y is 0.01 to 0.1, z Of the raw material powder is adjusted so as to satisfy 0.95 to 1.05. As the raw material powder, La ₂ O ₃ powder and Ni, Cu, Fe metal oxide powders, or those that can form oxides by heat treatment, such as carbonates, nitrates, acetates of each metal, etc. After preparing this so that it may become the said compositional formula, this is calcined at 1000-1200 degreeC, and a solid solution process is carried out. Thereafter, the solid solution is pulverized to obtain a solid solution powder.

This solid solution powder is substantially composed of a perovskite type complex oxide represented by La (Ni _x Cu _y Fe _1-xy ) _z O ₃ , and other crystal phases are substantially absent. .

  Then, a slurry is prepared using this solid solution powder, and the slurry is applied to and dried on the surface of a solid electrolyte prepared in advance, or a green sheet is prepared by a doctor blade method or the like using the solid solution powder. This is laminated on the surface of the solid electrolyte to form an oxygen electrode molded body layer.

  Next, these laminated bodies are baked at a temperature of 1300 to 1600 ° C. for about 2 to 15 hours in an oxidizing atmosphere such as air, thereby forming an oxygen electrode made of the conductor of this embodiment on the surface of the solid electrolyte. .

  Also, a fuel cell formed body layer can be formed on the surface of the solid electrolyte opposite to the surface on which the oxygen electrode is formed and fired to produce a fuel cell.

  The fuel cell houses a large number of the fuel cells in a storage container, and electrically connects the many fuel cells in series. That is, the oxygen electrode of one fuel battery cell and the fuel electrode of the other adjacent fuel battery cell are electrically connected by the current collecting member. Details will be described later.

Conductors, when expressed the composition formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, x is 0.5 to 0.6, y is 0.01 to 0.1 , Z satisfies 0.95 to 1.05, so that the conductivity at high temperature can be increased. When this conductor is used as the oxygen electrode of the fuel cell, the high temperature region of the oxygen electrode, 600 It is possible to increase the electrical conductivity at a temperature not lower than 700 ° C., particularly not lower than 700 ° C., and improve the power generation performance as a fuel cell, and the power generation performance can also be improved as a fuel cell having many such fuel cells.

  In the above embodiment, the case where the conductor is used as the oxygen electrode material of the fuel battery cell has been described. For example, the conductor of this embodiment is used as a conductive bonding material for electrically connecting the fuel battery cells. Can do. Details will be described later.

  Further, in the above embodiment, the oxygen electrode 3 is formed on the upper surface of the solid electrolyte 1 and the fuel electrode 5 is formed on the lower surface. However, the intermediate electrode is interposed between the solid electrolyte 1 and the oxygen electrode 3 and between the solid electrolyte 1 and the fuel electrode 5. Of course, a layer may be formed.

  A cell stack apparatus 1 including the cell stack of the present invention will be described with reference to FIG. 3 to 6, for easy understanding, the cross-sectional view shows the thickness and the like enlarged or reduced, and the side view shows the length and the width enlarged and reduced.

The cell stack device 11 has a pair of opposing main surfaces. On one main surface of the columnar conductive support 17 as a whole, a fuel electrode 18 as an inner electrode layer, a solid electrolyte 19, The fuel cell unit 13 includes a power generation unit that is formed by stacking the oxygen electrode 20 as an outer electrode layer in this order. Inside the conductive support 17, a plurality of gas flow paths 22 are formed in the length direction.

  The fuel cell 13 has a columnar shape (hollow flat plate shape) in which an interconnector 21 is stacked on the other side of the conductive support 17. A plurality of these fuel cells 13 are arranged in one row, and adjacent fuel cells 13 are arranged. A current collecting member 14 is disposed between the battery cells 13, and the fuel battery cells 13 are electrically connected in series to form a cell stack 12.

  As will be described in detail later, the fuel battery cell 13 and the current collecting member 14 are joined via a conductive joining material 23, whereby a plurality of fuel battery cells 13 are electrically connected via the current collecting member 14. And the cell stack 12 is mechanically bonded.

In addition, a current collector layer can be formed on the surface of the oxygen electrode 20 of the fuel cell, and the above-described conductor can be used as the current collector layer. That is, by forming a current collector layer having better conductivity than that of the oxygen electrode 20 on the surface of the oxygen electrode 20, it is possible to improve current collection characteristics from the fuel cell. Such current collector layer, as described above, when representing the formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, x is 0.5 to 0.6 , Y satisfying 0.01 to 0.1 and z satisfying 0.95 to 1.05 can be used. When the conductor is used as the oxygen electrode 20, it is not necessary to use the conductor described above as the current collector layer on the surface of the oxygen electrode layer 2.

  Also, a P-type semiconductor layer (not shown) can be provided on the outer surface of the interconnector 21. By connecting the current collecting member 14 to the interconnector 21 via the P-type semiconductor layer, the contact between them becomes an ohmic contact, and the potential drop can be reduced.

  That is, as can be understood from the shape shown in FIG. 4, the conductive support 17 includes a pair of parallel flat surfaces n and arcuate surfaces (side surfaces) m that connect the pair of flat surfaces n, respectively. It consists of Both surfaces of the flat surface n are formed substantially parallel to each other, and a porous fuel electrode 18 is provided so as to cover one flat surface n (lower surface) and the arcuate surfaces m on both sides. A dense solid electrolyte 19 is laminated so as to cover 18. A porous oxygen electrode 20 is laminated on the solid electrolyte 19 so as to face the fuel electrode 18.

  In other words, the fuel electrode 18 and the solid electrolyte 19 are formed up to the other flat surface n (upper surface) via the arcuate surfaces m at both ends of the conductive support 17, and interconnectors are formed at both ends of the solid electrolyte 19. The both ends of 21 are joined, the electroconductive support body 17 is surrounded by the solid electrolyte 19 and the interconnector 21, and it is comprised so that the fuel gas which distribute | circulates the inside may not leak outside.

  And the lower end part of each fuel cell 13 which comprises the cell stack 12 is fixed to the gas tank 16 with sealing materials (not shown), such as glass, the cell stack apparatus 11 is comprised, and fuel gas is The fuel cell 13 is supplied via a gas flow path 22 provided inside the fuel cell 13.

  In the cell stack device 11 shown in FIG. 3, the hydrogen-containing gas flows as fuel gas in the gas flow path 22 of the fuel cell 13, and the inside of the current collecting member 14 disposed between the fuel cells 13 An oxygen-containing gas (air) flows. As a result, the fuel gas is supplied from the gas tank 16 to the fuel electrode 18, and the oxygen-containing gas is supplied to the oxygen electrode 20 through the inside of the current collecting member 14, thereby generating power in the fuel cell 13. In the following description, the outer electrode layer is described as the oxygen electrode 20, and the inner electrode layer is described as the fuel electrode 18.

The cell stack device 11 includes cell stacks 1 from both ends of the fuel cell 13 in the arrangement direction x.
2, an elastically deformable conductive member 15 having a lower end fixed to the gas tank 16 is provided. Here, the conductive member 15 shown in FIG. 3 has a flat plate portion 15 a provided so as to be positioned at both ends of the cell stack 12 and a shape extending outward along the arrangement direction x of the fuel cells 13. And a current extraction part 15b for extracting a current generated by the power generation of the cell stack 12 (fuel cell 13).

Below, each member which comprises the fuel cell 13 is demonstrated. As the fuel electrode 18, a generally known one can be used, and porous conductive ceramics such as ZrO ₂ (referred to as stabilized zirconia) in which a rare earth element is dissolved, Ni and / or NiO, Can be formed from

The solid electrolyte 19 has a function as an electrolyte that bridges electrons between the electrodes, and at the same time, is required to have a gas barrier property in order to prevent leakage between the fuel gas and the oxygen-containing gas. It is formed from ZrO ₂ in which ₃ to 15 mol% of a rare earth element is dissolved. In addition, as long as it has the said characteristic, you may form using other materials, such as a lanthanum gallate.

The oxygen electrode 20 is not particularly limited as long as it is generally used. For example, the oxygen electrode 20 can be formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. The oxygen electrode 20 needs to have gas permeability, and can have an open porosity of 20% or more, particularly 30 to 50%. As the oxygen electrode 20, the above-mentioned conductor, i.e., when representing the formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, x is 0.5 to 0.6, y A conductor satisfying 0.01 to 0.1 and z satisfying 0.95 to 1.05 can be used.

Although the interconnector 21 can be formed from conductive ceramics, it is required to have reduction resistance and oxidation resistance because it is in contact with a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air, etc.). Therefore, lanthanum chromite (LaCrO ₃ ) can be used. The interconnector 21 is dense in order to prevent leakage of the fuel gas flowing through the plurality of gas flow paths 22 formed in the conductive support 17 and the oxygen-containing gas flowing outside the conductive support 17. The relative density is preferably 93% or more, particularly 95% or more.

  The conductive support 17 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode 18 and to be conductive in order to collect current via the interconnector 21. . Therefore, it is necessary to use a material that satisfies this requirement as the conductive support member 17, and for example, conductive ceramics, cermets, and the like can be used.

  In the production of the fuel cell 13, in the case of producing the conductive support 17 by co-firing with the fuel electrode 18 or the solid electrolyte 19, the conductive support is composed of an iron group metal component and a specific rare earth oxide. 17 can be formed. The conductive support 17 preferably has an open porosity of 30% or more, particularly 35 to 50% in order to provide the required gas permeability, and the conductivity is 50 S / cm or more. Further, it may be 300 S / cm or more and 440 S / cm or more.

Furthermore, as a P-type semiconductor layer (not shown), a layer made of a transition metal perovskite oxide can be exemplified. Specifically, those having higher electronic conductivity than lanthanum chromite constituting the interconnector 21, for example, lanthanum manganite (LaSrMnO ₃ ), lanthanum ferrite (LaSrFeO ₃ ) in which Mn, Fe, Co, etc. exist at the B site. P-type semiconductor ceramics made of at least one of lanthanum cobaltite (LaSrCoO ₃ ) and the like can be used. In general, the thickness of such a P-type semiconductor layer is preferably in the range of 30 to 100 μm.

  The conductive bonding material 23 is provided for bonding the fuel cell 13 and the current collecting member 14 and can be formed using conductive ceramics or the like. As the conductive ceramic, the same ceramics that form the oxygen electrode 20 can be used.

Specifically, LaSrCoFeO ₃ , LaSrMnO ₃ , LaSrCoO ₃ or the like can be used. These materials may be manufactured using a single material, or the conductive bonding material 23 may be manufactured by combining two or more kinds.

Further, the above-described conductor can be used as the conductive bonding material 23. That is, the conductive bonding material 23, when representing the formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, x is 0.5 to 0.6, y is 0. In the case of being made of a conductor satisfying 01 to 0.1 and z satisfying 0.95 to 1.05, the conductivity in the high temperature region of the conductive bonding material 23 can be increased, and between a plurality of fuel cells. The electrical resistance of the cell stack 12 can be improved.

  Next, the current collecting member 14 will be described with reference to FIG. The current collecting member 14 includes a plurality of plate-like first cell facing portions 14a1 joined to one adjacent fuel cell 13 and plates extending from both sides of the first cell facing portion 14a1 so as to be separated from the fuel cells. A first cell-like separation portion 14a2, a plurality of plate-like second cell facing portions 14b1 joined to the other adjacent fuel cell 13, and from both sides of the second cell facing portion 14b1 so as to be separated from the fuel cells. And an extended plate-like second separation portion 14b2.

  Further, the first connection portion 14c that connects one ends of the plurality of first separation portions 14a2 and the plurality of second separation portions 14b2, and the other ends of the plurality of first separation portions 14a2 and the plurality of second separation portions 14b2 The second connecting portion 14d to be connected is a set of units, and a plurality of sets of these units are connected in the longitudinal direction of the fuel cell 13 by the conductive connecting pieces 14e. As shown in FIG. 6, the first cell facing portion 14 a 1 and the second cell facing portion 14 b 1 are portions that are joined to the fuel battery cell 13, and these portions are portions for entering and leaving the generated power of the fuel battery cell 13. It has become.

  That is, the fuel cell 13 and the first cell facing portions 14 a 1 and 14 b 1 of the current collecting member 14 are joined by the conductive joining material 23. In other words, the plurality of fuel cells 13 have a flat portion, and the flat portion has the interconnector 21, and the first cell facing portion 14 a 1 faces the interconnector 21. Are joined by a conductive joining material 23. FIG. 6B is a longitudinal sectional view taken along line CC in FIG.

  In the fuel battery cell 13, as described above, a portion where the fuel electrode 18 and the oxygen electrode 20 face each other through the solid electrolyte 19 is a portion that generates power. Therefore, in order to efficiently collect the current generated by the power generation unit of the fuel cell 13, the length of the current collecting member 14 along the longitudinal direction of the fuel cell 13 is the outer electrode layer in the fuel cell 13. It is preferable that the length is equal to or greater than 20 in the longitudinal direction.

  The current collecting member 14 needs to have heat resistance and conductivity, and can be made of a metal or an alloy. In particular, the current collecting member 14 can be made from an alloy containing Cr at a rate of 4 to 30% because it is exposed to a high-temperature oxidizing atmosphere, and can be made of an Fe—Cr alloy or Ni—Cr alloy. It can be made of an alloy or the like.

  Further, since the current collecting member 14 is exposed to a high-temperature oxidizing atmosphere when the cell stack apparatus 11 is operated, an oxidation resistant coating may be applied to the surface of the current collecting member 14. Thereby, deterioration of the current collecting member 14 can be reduced. It is preferable to apply the oxidation resistant coating to the entire surface of the current collecting member 14. Thereby, it can suppress that the surface of the current collection member 14 is exposed to high temperature oxidation atmosphere.

  Here, the manufacturing method of the current collection member 14 is demonstrated. A single rectangular plate member is pressed to form a plurality of slits extending in the width direction of the plate member in the longitudinal direction of the plate member. And the current collection member shown in FIG. 5 is made to project alternately by the site | part between the slit used as the 1st cell facing part 14a1, the 1st cell separation part 14a2, the 2nd cell facing part 14b1, and the 2nd cell separation part 14b2. 14 can be produced.

  Next, the fuel cell module 30 in which the cell stack device 11 is stored in the storage container 31 will be described with reference to FIG.

  A fuel cell module 30 shown in FIG. 7 includes a reformer 32 for reforming raw fuel such as natural gas or kerosene to generate fuel gas to obtain fuel gas used in the fuel cell 13. It is arranged above the cell stack 12. The fuel gas generated by the reformer 32 is supplied to the gas tank 16 via the gas flow pipe 33 and supplied to the gas flow path 22 provided inside the fuel battery cell 13 via the gas tank 16. .

  FIG. 7 shows a state in which a part (front and rear surfaces) of the storage container 31 is removed and the cell stack device 11 and the reformer 32 housed inside are taken out rearward. Here, in the fuel cell module 30 shown in FIG. 7, the cell stack device 11 can be slid and stored in the storage container 31.

  Further, in FIG. 7, the oxygen-containing gas introduction member 34 provided inside the storage container 31 is disposed between the cell stacks 12 juxtaposed to the gas tank 16, and the oxygen-containing gas matches the flow of the fuel gas. Thus, the oxygen-containing gas is supplied to the lower end side of the fuel cell 13 so that the fuel cell 13 flows laterally from the lower end side toward the upper end side. The surplus fuel gas (fuel offgas) that has not been used for power generation discharged from the gas flow path 22 of the fuel battery cell 13 is burned above the fuel battery cell 13, so that the temperature of the cell stack 12 is effectively increased. The cell stack device 11 can be started quickly. Further, the reformer 32 disposed above the cell stack 12 is burned above the fuel cell 13 by burning the fuel gas discharged from the gas flow path 12 of the fuel cell 13 and not used for power generation. Can be warmed. Thereby, the reforming reaction can be efficiently performed in the reformer 32.

  Next, a fuel cell device 35 in which a fuel cell module 30 and an auxiliary machine (not shown) for operating the fuel cell module 30 are housed in an outer case will be described with reference to FIG.

  A fuel cell device 35 shown in FIG. 8 has a module housing chamber in which an outer case made up of support columns 36 and an outer plate 37 is vertically divided by a partition plate 38 and the upper side thereof stores the above-described fuel cell module 30. 39, the lower side is configured as an auxiliary equipment storage chamber 40 for storing auxiliary equipment for operating the fuel cell module 30. In addition, the auxiliary machine accommodated in the auxiliary machine storage chamber 40 is abbreviate | omitted.

In addition, the partition plate 38 is provided with an air circulation port 41 for allowing the air in the auxiliary machine storage chamber 40 to flow toward the module storage chamber 39, and a part of the exterior plate 37 constituting the module storage chamber 39, An exhaust port 42 for exhausting air in the module storage chamber 39 is provided.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, in the above embodiment, the hollow flat plate fuel cell 13 is used, but a cylindrical fuel cell and a flat plate fuel cell may be used.

  Moreover, in the said form, although the fuel cell 13 which has the interconnector 21 was used, the fuel cell which does not have an interconnector can also be used.

  Furthermore, in the said form, although the current collection member 14 as shown in FIG. 5 was used, it is not limited to this, The cell stack which does not use a current collection member may be sufficient. Moreover, in FIG. 5, although it has the 1st connection part 14c and the 2nd connection part 14d, the case where it has any one connection part may be sufficient.

  Furthermore, although the said form demonstrated the conductor for fuel cells, if it is a conductor used in a high temperature range, it can be used besides a fuel cell use.

When La (OH) ₃ powder, NiO powder, CuO powder, and Fe ₂ O ₃ powder are used, the composition formula by molar ratio is expressed as La (Ni _x Cu _y Fe _1-xy ) _z O ₃ , x , Y and z were prepared so as to satisfy the values shown in Table 1, and calcined at 1200 ° C. to form a solid solution, and the solid solution was pulverized to obtain a calcined powder.

  A test piece was formed by adding paraffin wax to the calcined powder, and fired at 1400 ° C. in the air to obtain a conductor.

  Thereafter, when X-ray diffraction measurement was performed, it was confirmed that the main phase was composed of a perovskite complex oxide. Further, the presence or absence of a peak in a crystal phase other than the main phase was confirmed, and Table 1 shows the presence or absence of a by-product phase. In the X-ray diffraction chart, it was determined that there was no by-product phase when only a peak made of a perovskite complex oxide could be confirmed. In FIG. 5 shows an X-ray diffraction chart.

  Moreover, when the conductor was analyzed by ICP emission spectroscopic analysis, it was confirmed to be x, y, and z in Table 1.

  Further, for this conductor, the current and voltage were measured by the four-terminal method while raising the temperature in the firing furnace, and the electronic conductivity at 600 to 850 ° C. was determined from the results, and 700 ° C., 750 ° C., 800 ° C. The electrical conductivity in is shown in Table 1. Sample No. FIG. 9 shows the temperature characteristics of conductivity for 1, 5, 8, and 11.

  Moreover, the thermal expansion coefficient in 850 degreeC was measured by the average linear expansion coefficient measurement (JISR1618-1994), and those results were also described in Table 1.

Furthermore, the composition formula by molar ratio is similarly applied to (La _0.6 Sr _0.4 ) (Co _0.2 Fe _0.8 ) O ₃ and La (Ni _0.6 Fe _0.4 ) O _3. The sample No. in Table 1 was evaluated. 1 and 2.

From Table 1, the conductivity is higher than that of the conventional materials (La _0.6 Sr _0.4 ) (Co _0.2 Fe _0.8 ) and La (Ni _0.6 Fe _0.4 ) O _3. Sample No. In 4, 5, 8-11, 13, and 14, it turns out that the electrical conductivity in 700-800 degreeC is high, and the change rate of the electrical conductivity with respect to temperature is low.

Furthermore, in the sample of the present invention, the average linear expansion coefficient is 8YSZ, which is a typical electrolyte material, compared to (La _0.6 Sr _0.4 ) (Co _0.2 Fe _0.8 ) which is a conventional material. Since it is closer to the average linear expansion coefficient (10.46 × 10 ⁶ / K) of (8 mol Y ₂ O ₃ stabilized ZrO ₂ ), cracks at the interface due to incompatibility of the thermal expansion coefficient during use at high temperatures, It turns out that generation | occurrence | production of curvature can be suppressed.

First, a NiO powder having an average particle size of 0.5 μm and a Y ₂ O ₃ powder having an average particle size of 0.9 μm are mixed, and a clay prepared with an organic binder and a solvent is molded by an extrusion molding method and dried. A conductive support molded body was prepared by degreasing.

Next, using a slurry obtained by mixing a ZrO ₂ powder (solid electrolyte raw material powder) having a particle size of 0.8 μm by solid micro-solution method in which 8 mol% of Y is dissolved, an organic binder and a solvent, A solid electrolyte sheet having a thickness of 30 μm was prepared by a blade method.

Next, a slurry for a fuel electrode is prepared by mixing a NiO powder having an average particle size of 0.5 μm, a ZrO ₂ powder in which Y ₂ O ₃ is dissolved, an organic binder, and a solvent, and the slurry is applied on a solid electrolyte sheet to produce a fuel. An electrode body was formed. Then, it laminated | stacked on the predetermined position of the electroconductive support body molded body with the surface by the side of a fuel electrode molded body facing down.

  Subsequently, the laminated molded body in which the molded bodies were laminated as described above was calcined at 1000 ° C. for 3 hours.

Next, an intermediate layer slurry prepared by adding an acrylic binder and a solvent to CeO ₂ in which GdO _1.5 is dissolved and mixing them is obtained on the solid electrolyte calcined body of the obtained laminated calcined body. Then, it was applied by a screen printing method to produce an intermediate layer molded body.

_{Subsequently,} the _{La (Mg 0.3 Cr 0.7) 0.96} O 3, to prepare a slurry of a mixture of organic binder and a solvent, to prepare a interconnector sheet.

  The raw material which consists of Ni and YSZ was mixed and dried, the organic binder and the solvent were mixed, and the slurry for adhesion layers was adjusted. The prepared slurry for the adhesion layer was applied to a portion of the conductive support where the fuel electrode (and solid electrolyte) was not formed (a portion where the conductive support was exposed) to laminate the adhesion layer molded body. An interconnector sheet was laminated on the adhesion layer molded body.

  Subsequently, the above-mentioned laminated molded body was subjected to binder removal treatment and co-fired at 1450 ° C. for 2 hours in the air.

Next, a mixed liquid composed of La (Ni _0.6 Cu _0.05 Fe _0.35 ) O ₃ powder having an average particle diameter of 2 μm and isopropyl alcohol is prepared and sprayed on the surface of the intermediate layer of the laminated sintered body. This was applied to form an air electrode layered body, which was baked at 1145 ° C. for 4 hours to form an oxygen electrode. Thus, a fuel cell shown in FIG. 4 was produced. In addition, (La _0.6 Sr _0.4 ) (Co _0.2 Fe _0.8 ) O ₃ and La (Ni _0.6 Fe _0.4 ) O are formed on the intermediate layer surface of the laminated sintered body. Using the powder No. ₃ , an air electrode molded body was formed in the same manner as described above, and baked at 1145 ° C. for 4 hours to form an oxygen electrode, thereby producing a fuel cell of a comparative example.

  The size of the produced fuel cell is 25 mm × 200 mm, the thickness of the conductive support (thickness between the flat surfaces n) is 2 mm, the open porosity is 35%, the thickness of the fuel electrode is 10 μm, and the open porosity is 24. %, The thickness of the oxygen electrode was 50 μm, the open porosity was 40%, and the relative density of the solid electrolyte was 97%.

  Next, hydrogen gas was allowed to flow inside the fuel cell, and the conductive support and the fuel electrode were subjected to reduction treatment at 850 ° C. for 10 hours.

The fuel gas is circulated through the fuel gas flow path of the fuel cell, the air is circulated outside the fuel cell, the fuel cell is heated to 750 ° C. using an electric furnace, and a power generation test is conducted. Polarization resistance (0.19 A / cm ² (6 A)) and output density (at 0.7 V) were measured.

As a result, in the case of an oxygen electrode made of La (Ni _0.6 Cu _0.05 Fe _0.35 ) O ₃ , the output density and polarization resistance are 0.372 W / cm ² and 125 mV, and (La _{0 .6} Sr _0.4 ) (Co _0.2 Fe _0.8 ) O _{3 in} the case of an oxygen electrode, 0.47 W / cm ² and 48 mV, and La (Ni _0.6 Fe _0.4 ) In the case of an oxygen electrode made of O ₃ , the voltage was 0.372 W / cm ² and 128 mV. This shows that the conductor of this embodiment can be used as an oxygen electrode.

DESCRIPTION OF SYMBOLS 1, 19 ... Solid electrolyte 3, 20 ... Oxygen electrode 5, 18 ... Fuel electrode 23 ... Conductive joining material 12 ... Cell stack 13 ... Solid oxide fuel cell 14 ... Current collecting member 31 ... Storage container

Claims (7)

When representing the composition formula by molar ratio _{La (Ni x Cu y Fe 1} -x-y) z O 3, wherein x is 0.5 to 0.6, wherein y is 0.01 to 0.1, wherein A conductor comprising a perovskite complex oxide satisfying z of 0.95 to 1.05. 2. The conductor according to claim 1, comprising La at the A site, Ni, Cu, and Fe at the B site, and a perovskite complex oxide represented by a general formula of ABO ₃ .   A solid oxide fuel cell comprising an oxygen electrode on one side of the solid electrolyte and a fuel electrode on the other side, wherein the oxygen electrode is made of the conductor according to claim 1.   A plurality of solid oxide fuel cells each having an oxygen electrode on one side and a fuel electrode on the other side of the solid electrolyte, and a conductive junction for electrically connecting the plurality of solid oxide fuel cells A cell stack comprising the conductor according to claim 1, wherein the conductive bonding material is made of the conductor according to claim 1.   A current collecting member is disposed between a plurality of adjacent solid oxide fuel cells, and the solid oxide fuel cells and the current collecting member are joined by the conductive joining material. The cell stack according to claim 4.   A plurality of solid oxide fuel cells according to claim 3 are accommodated in a storage container, and the plurality of solid oxide fuel cells are electrically connected to each other. .   A fuel cell comprising the cell stack according to claim 4 or 5 in a storage container.