JP5328275B2 - Cell stack, fuel cell module including the same, and fuel cell device - Google Patents

Description

  The present invention relates to a cell stack, a fuel cell module including the cell stack, and a fuel cell device.

  In recent years, various fuel cell modules in which a cell stack formed by electrically connecting a plurality of fuel cells is accommodated in a storage container have been proposed as next-generation energy.

  In the cell stack, a current collecting member is arranged between a plurality of fuel cells, and the fuel cells adjacent to the current collecting member are joined by a joining material or the like, whereby the fuel cells are electrically connected in series. Consists of connecting.

Here, a method for applying a surface treatment material made of a perovskite oxide having a different average particle diameter to the surface of the current collecting member when joining the current collecting member and the fuel cell is proposed (for example, a patent) Reference 1). It has also been proposed to configure the air electrode using electrode particles having different average particle diameters (see, for example, Patent Document 2).
JP 2004-265742 A JP 2007-27036 A

  However, even in such a cell stack, cracks or the like may occur in the bonding material that bonds the air electrode and the current collecting member during long-term power generation. Here, when stress is generated in the current collecting member, the current collecting member may be peeled off from the bonding material or the air electrode, which may reduce the output of the cell stack.

  Therefore, it is conceivable to join the current collecting member more firmly by reducing the porosity of the conductive bonding material and the air electrode layer. In that case, a sufficient amount for the air electrode constituting the fuel cell is sufficient. There was a possibility that the power generation efficiency could be lowered due to the failure to supply the air.

  Therefore, in the present invention, even when long-term power generation is performed, good connection between the air electrode and the current collecting member can be continuously performed, improving long-term reliability and improving power generation efficiency. It is an object of the present invention to provide a cell stack that can be used, a fuel cell module including the cell stack, and a fuel cell device.

The cell stack of the present invention includes a fuel electrode layer, a solid electrolyte layer, and an air electrode layer laminated in this order on the surface of a conductive support substrate, and an interconnector electrically connected to the fuel electrode layer. A plurality of solid oxide fuel cell units are provided, and the air electrode layer of one of the adjacent solid oxide fuel cell units and the interconnector of the other solid oxide fuel cell unit are electrically conductively joined. A cell stack electrically connected in series by a current collecting member connected through a material, wherein the air electrode layer has a perovskite complex oxide having an average particle size of 1 μm or less as a main component. And the conductive bonding material connecting the air electrode layer and the current collector is a perovskite complex oxide having an average particle size of 3 μm or more and a perovskite complex acid having an average particle size of 1 μm or less. With a sintered body composed mainly of things, the porosity of the air electrode layer is, the much larger than the porosity of the conductive bonding material is connected to the air electrode layer, further, said air electrode layer A second air electrode layer is formed between the solid electrolyte layer, and the porosity of the air electrode layer depends on the porosity of the conductive bonding material connected to the air electrode layer and the second air electrode. and wherein the magnitude Ikoto than the porosity of the layer.

  In such a cell stack, the conductive bonding material for connecting the air electrode layer and the current collector is mainly composed of a perovskite complex oxide having an average particle size of 3 μm or more and a perovskite complex oxide having an average particle size of 1 μm or less. Since it consists of the sintered compact as a component, the firing shrinkage of the conductive bonding material can be suppressed, and thereby the generation of cracks can be suppressed. Thereby, long-term reliability can be improved.

  Further, since the air electrode layer is made of a sintered body mainly composed of a perovskite complex oxide having an average particle size of 1 μm or less, the initial power generation output of the fuel cell can be improved and the power generation efficiency can be improved. be able to.

  Furthermore, since the porosity of the air electrode layer is larger than the porosity of the conductive bonding material connected to the air electrode layer, a sufficient amount of air (oxygen-containing gas) can be introduced into the air electrode layer. The air utilization characteristics can be improved, and the power generation efficiency can be improved. In addition, by making the porosity of the conductive bonding material connected to the air electrode layer smaller than the porosity of the air electrode layer, the bonding strength between the current collector and the conductive bonding material can be improved, Reliability can be improved.

Furthermore , the porosity of the second air electrode layer formed between the air electrode layer and the solid electrolyte layer is larger than the porosity of the conductive bonding material connected to the first air electrode layer. In addition to improving the bonding strength between the current collecting member and the conductive bonding material, a sufficient amount of air (oxygen-containing gas) can be introduced into the air electrode layer.

  Further, the porosity of the air electrode layer is larger than the porosity of the second air electrode layer formed between the air electrode layer and the solid electrolyte layer, that is, the porosity of the second air electrode layer is Since the porosity of the air electrode layer located above the second air electrode layer is smaller than that of the air electrode layer, the bonding strength between the second air electrode layer and the solid electrolyte layer can be improved.

In the cell stack of the present invention , the fuel electrode layer, the solid electrolyte layer, and the air electrode layer are laminated in this order on the surface of the conductive support substrate, and the interconnector is electrically connected to the fuel electrode layer. A plurality of solid oxide fuel cells, each of which is electrically conductive to the air electrode layer of one of the adjacent solid oxide fuel cells and the interconnector of the other solid oxide fuel cell. A cell stack electrically connected in series by a current collecting member connected via a conductive bonding material, wherein the air electrode layer is a sintered body mainly composed of a perovskite complex oxide having an average particle size of 1 μm or less. The conductive bonding material comprising a bonded body and connecting the air electrode layer and the current collecting member is a perovskite complex oxide having an average particle size of 3 μm or more and a perovskite type having an average particle size of 1 μm or less Said coupling oxide with a sintered body composed mainly, the porosity of the air electrode layer is, the larger than the porosity of the conductive bonding material is connected to the air electrode layer, and the current collecting member The conductive bonding material for connecting the interconnector is made of a sintered body mainly composed of a perovskite complex oxide, and the porosity of the conductive bonding material connected to the interconnector is It is smaller than the porosity of the conductive bonding material connected to the air electrode layer .
In this case, a second air electrode layer is formed between the air electrode layer and the solid electrolyte layer, and the porosity of the air electrode layer is that of the conductive bonding material connected to the air electrode layer. It is desirable that the porosity is larger than the porosity of the second air electrode layer.

  In such a cell stack, the porosity of the conductive bonding material made of a sintered body mainly composed of a perovskite complex oxide for connecting the interconnector and the current collecting member is connected to the air electrode layer. Therefore, the current generated by the power generation of the fuel cell can be collected efficiently. Thereby, a cell stack with improved power generation efficiency can be obtained.

  The fuel cell module of the present invention is characterized in that the cell stack according to any one of the above is housed in a housing container.

  In such a fuel cell module, since the cell stack with improved long-term reliability is stored in the storage container, the fuel cell module with improved long-term reliability can be obtained.

  The fuel cell device of the present invention is characterized in that the fuel cell module described above is housed in an outer case.

  In such a fuel cell device, since the fuel cell module in which the cell stack having improved long-term reliability is stored in the storage container is stored in the outer case, the fuel cell device having improved long-term reliability. It can be.

The cell stack of the present invention can continuously perform good connection between the air electrode and the current collecting member , improve long-term reliability, improve power generation efficiency, and further generate power. By providing the cell stack with improved efficiency, a fuel cell module and a fuel cell device with improved power generation efficiency can be obtained.

  FIG. 1 shows an example of a cell stack apparatus 1 comprising the cell stack of the present invention, where (a) is a side view schematically showing the cell stack apparatus 1 and (b) is (a). FIG. 2 is a partially enlarged plan view of the cell stack device 1 of FIG. 2 and shows an excerpt of a portion surrounded by a dotted frame shown in FIG. The same members are assigned the same numbers, and so on. In addition, in (b), in order to clarify, the part corresponding to the part enclosed with the dotted-line frame shown by (a) is shown with the arrow.

  Here, the cell stack constituting the cell stack device 1 is one of a columnar conductive support substrate 11 (hereinafter sometimes abbreviated as the support substrate 11) composed of a pair of opposed flat portions and arc-shaped portions at both ends. A fuel electrode layer 8 is provided so as to cover the flat portion and the arc-shaped portion, and a dense solid electrolyte layer 9 is laminated so as to cover the fuel electrode layer 8. An air electrode layer 10 is provided on the solid electrolyte layer 9 so as to face the fuel electrode layer 8. That is, the fuel electrode layer 8, the solid electrolyte layer 9, and the air electrode layer 10 are laminated in this order on one flat portion of the support substrate 11. An interconnector 13 is laminated on the other flat portion of the support substrate 11 on which the fuel electrode layer 8 and the solid electrolyte layer 9 are not formed. With such a configuration, columnar solid oxide fuel cells 2 (hereinafter may be abbreviated as fuel cells 2) are formed. As is clear from FIG. 1B, the fuel electrode layer 8 and the solid electrolyte layer 9 extend to both sides of the interconnector 13 via arcuate portions at both ends, and the surface of the support substrate 11 is external. It is configured not to be exposed.

  A plurality of the fuel cells 2 are electrically connected in series with the current collecting member 3 interposed between the adjacent fuel cells 2 to constitute a cell stack. The current collecting member 3 interposed between the adjacent fuel cells 2 is connected to the air electrode layer 10 of one fuel cell 2 via the conductive bonding material 14, and the other fuel cell 2 The interconnector 13 and the conductive bonding material 15 are connected to each other, whereby the fuel cells 2 are electrically connected in series.

  Then, the lower end of each fuel battery cell 2 constituting the cell stack described above is fixed to a manifold 6 for supplying a reaction gas (for example, fuel gas) to the fuel battery cell 2, and the lower end is fixed to the manifold 6. An end current collecting member 4 is disposed so as to sandwich the cell stack from both ends in the arrangement direction of the battery cells 2 via the current collecting member 3, and a reaction gas supply pipe 7 for supplying a reaction gas to the manifold 6 is provided. The cell stack device 1 is configured by being connected.

  Here, in the end current collecting member 4 shown in FIG. 1, a current drawing portion that extends outward along the arrangement direction of the fuel cells 2 and draws a current generated by the power generation of the fuel cells 2. 5 is provided.

  A plurality of gas flow paths 12 are provided inside the support substrate 11 constituting the fuel battery cell 2, and fuel gas (hydrogen-containing gas) supplied from the manifold 6 flows through the gas flow paths 12. In the meantime, the fuel electrode layer 8 is supplied.

  The support substrate 11 can also serve as a fuel-side electrode, and the fuel cell 2 can be configured by sequentially laminating the solid electrolyte layer 9 and the air-side electrode layer 10 on the surface thereof. Various types of fuel cells are known as the fuel cell 2. However, in order to reduce the size and increase the efficiency of the fuel cell device containing the fuel cell 2, the solid oxide fuel cell It can be. Thereby, the fuel cell device can be reduced in size and increased in efficiency, and a load following operation can be performed to follow a fluctuating load required for a household fuel cell.

  Below, each member which comprises the fuel cell 2 shown in FIG. 1 is demonstrated. The air electrode layer 10, the interconnector 13, and the conductive bonding materials 14 and 15 will be described later.

  Since the support substrate 11 is required to be gas permeable in order to permeate the fuel gas to the fuel electrode layer 8 and to be conductive in order to collect current via the interconnector 13, for example, It is preferably formed of an iron group metal component and a specific rare earth oxide.

  Examples of the iron group metal component include an iron group metal element, an iron group metal oxide, an iron group metal alloy or an alloy oxide, and the like. More specifically, for example, iron group metals include Fe, Ni (nickel), and Co. Since they are particularly inexpensive and stable in fuel gas, Ni and / or NiO are used as iron group components. It is preferable to contain.

The specific rare earth oxide is used to bring the thermal expansion coefficient of the support substrate 11 close to the thermal expansion coefficient of the solid electrolyte layer 9, and is Y, Lu (lutetium), Yb, Tm (thulium). A rare earth oxide containing at least one element selected from the group consisting of Er, Er (erbium), Ho (holmium), Dy (dysprosium), Gd, Sm, and Pr (praseodymium), in combination with the iron group component Used in. Specific examples of such rare earth oxides include Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , Tm ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ , Dy ₂ O ₃ , Gd ₂ O. ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified, and there is almost no solid solution or reaction with the iron group metal oxide, and the thermal expansion coefficient is almost the same as that of the solid electrolyte layer 9. And Y ₂ O ₃ and Yb ₂ O ₃ are preferable because they are inexpensive.

  In the present invention, the iron group metal component: rare earth oxide component = 35: 65-65 in that the good conductivity of the support substrate 11 is maintained and the thermal expansion coefficient is approximated to that of the solid electrolyte layer 9. : Preferably in a volume ratio of 35. The support substrate 11 may contain other metal components and oxide components as long as required characteristics are not impaired.

  Further, since the support substrate 11 is required to have fuel gas permeability, it is usually preferable that the open porosity is in the range of 30% or more, particularly 35 to 50%. Further, the conductivity of the support substrate 11 is preferably 300 S / cm or more, and particularly preferably 440 S / cm or more.

  The length of the flat portion of the support substrate 11 (length in the width direction of the support substrate 11) is normally 15 to 35 mm, and the length of the arc-shaped portion (arc length) is 2 to 8 mm. The thickness of the substrate 11 (thickness between both flat portions) is preferably 1.5 to 5 mm.

In the present invention, the fuel electrode layer 8 causes an electrode reaction, and is preferably formed by a known porous conductive ceramic (sintered body). For example, it is formed from ZrO _{2 in which a} rare earth element is dissolved or CeO _{2 in} which a rare earth element is dissolved, and Ni and / or NiO.

The content of ZrO ₂ in which the rare earth element is dissolved in the fuel electrode layer 8 or CeO ₂ in which the rare earth element is dissolved is preferably in the range of 35 to 65% by volume, and the Ni or NiO content is 65 to 35%. It is preferable that it is volume%. Further, the open porosity of the fuel electrode layer 8 is preferably 15% or more, particularly preferably in the range of 20 to 40%, and the thickness thereof is preferably 1 to 30 μm. For example, if the thickness of the fuel electrode layer 8 is too thin, the performance may be deteriorated, and if it is too thick, peeling due to a difference in thermal expansion may occur between the fuel electrode layer 8 and the solid electrolyte layer 9. .

The solid electrolyte layer 9 is a dense ceramic (sintered) made of partially stabilized or stabilized ZrO ₂ containing rare earth elements such as 3 to 15 mol% Y (yttrium), Sc (scandium), Yb (ytterbium). Body) is preferred. As the rare earth element, Y is preferable because it is inexpensive. Further, the solid electrolyte layer 9 is desirably a dense material having a relative density (according to Archimedes method) of 93% or more, particularly 95% or more in terms of preventing gas permeation, and a thickness of 5 to 50 μm. Preferably there is.

  By the way, the fuel cell 2 manufactured with the above-described configuration is connected to the current collecting member 3 via the conductive bonding materials 14 and 15 so that the plurality of fuel cells 2 are electrically connected in series. However, when power generation is performed for a long period of time, cracks may occur in the conductive bonding material 14 for connecting the current collecting member 3 and the air electrode layer 10, and the output of the cell stack may be reduced. As one of the causes, it is considered that the firing shrinkage of the conductive bonding material 14 is large, and the conductive bonding material 14 is cracked accordingly. In addition, depending on the particle size and porosity of the air electrode layer 10 and the conductive bonding materials 14 and 15, there is a possibility that the power generation performance may be reduced and the air utilization characteristics may be reduced.

  FIG. 2 is a cross-sectional view illustrating a part of the fuel cell 2, in which the air electrode layer 10 and the current collecting member 3 formed on the upper surface of the solid electrolyte layer 9 are connected via the conductive bonding material 14. Indicates that they are connected. Here, as shown in FIG. 2, the current collecting member 3 is connected so that a part thereof is buried in the conductive bonding material 14, and is not directly connected to the air electrode layer 10. It is preferable. Accordingly, the contact area between the current collecting member 3 and the conductive bonding material 14 can be increased, and the current collecting member 3 can be easily fixed.

Here, in order to suppress the above-mentioned problem (preventing), in the fuel cell 2, the sintered body air electrode layer 10 is mainly composed of an average particle diameter of 1μm or less of the perovskite type composite oxide The conductive bonding material 14 that connects the current collecting member 3 and the air electrode layer 10 is composed mainly of a perovskite complex oxide having an average particle diameter of 3 μm or more and a perovskite complex oxide having an average particle diameter of 1 μm or less. together it becomes a sintered body, the porosity of the air electrode layer 10, not greater than the porosity of the conductive bonding material 14 that is connected to the air electrode layer 10.

Specifically, the air electrode layer 10 is preferably formed of a conductive ceramic made of a sintered body mainly composed of a so-called ABO ₃ type perovskite complex oxide, and is preferably a transition metal perovskite oxide. In particular, Sr (strontium) and La (lanthanum) coexist at the A site, LaSrCoFeO ₃ -based oxide (for example, LaSrCoFeO ₃ ), LaMnO ₃ -based oxide (for example, LaSrMnO ₃ ), LaFeO ₃ -based oxide (for example, LaSrFeO ₃ ), At least one of LaCoO ₃ -based oxides (for example, LaSrCoO ₃ ) is preferable, and LaSrCoFeO ₃ -based oxides are particularly preferable from the viewpoint of high electrical conductivity at an operating temperature of about 600 to 1000 ° C. In the perovskite oxide, Fe (iron) or Mn (manganese) may exist at the B site together with Co (cobalt).

  Here, the air electrode layer 10 is composed of a sintered body of the perovskite oxide as described above, and has an average particle size of 1 μm or less. Thereby, the specific surface area with the air which circulates through the air electrode layer 10 can be increased, and thereby the initial power generation output of the fuel cell 2 can be improved. Accordingly, power generation efficiency can be improved.

  On the other hand, as the conductive bonding material 14 for connecting the air electrode layer 10 and the current collector 3, a sintered body of a perovskite oxide that can be used as the air electrode layer 10 can be used. It is composed of a perovskite oxide having a diameter of 3 μm or more (preferably in a range of 3 to 10 μm) and a perovskite oxide having a diameter of 1 μm or less.

  Accordingly, firing shrinkage of the conductive bonding material 14 can be suppressed, and generation of cracks in the conductive bonding material 14 can be suppressed. In suppressing the firing shrinkage of the conductive bonding material 14, the mixing ratio of the perovskite oxide having an average particle diameter of 3 μm or more and the perovskite oxide having an average particle diameter of 1 μm or less is 7: 3 to 3 by weight. A range of 9: 1 is preferred. Thereby, it is possible to ensure the conductivity between the fuel cells 2 while suppressing the generation of cracks, and to improve the long-term reliability.

Further, in the fuel cell 2, the porosity of the air electrode layer 10, not greater than the porosity of the conductive bonding material 14 that is connected to the air electrode layer 10. Thereby, a sufficient amount of air (oxygen-containing gas) can be introduced into the air electrode layer 10, and air utilization characteristics can be improved, so that power generation efficiency can be improved. Furthermore, the bonding strength between the current collecting member 3 and the conductive bonding material 14 is improved by making the porosity of the conductive bonding material 14 connected to the air electrode layer 10 smaller than the porosity of the air electrode layer 10. Long-term reliability can be improved.

  More specifically, since the air electrode layer 10 needs to have gas permeability, the porosity is preferably in a range larger than 40%, particularly in a range of 50 to 70%. 14 is a porosity smaller than that of the air electrode layer 10, and can be suitably set within a range of preferably 40 to 60%.

  The current collecting member 3 includes a pair of plate-like contact portions for contacting with adjacent fuel cells 2 provided at a predetermined interval, and one of the pair of contact portions. A current collecting member formed by continuously forming a plurality of conductive pieces having one end and a connecting portion that connects one end of the other contact portion in the longitudinal direction of the fuel cell 2 can be used.

  FIG. 3 is a cross-sectional view showing a part of the fuel cell 2 extracted from an example in which the second air electrode layer 16 is formed between the air electrode layer 10 and the solid electrolyte layer 9. .

  As shown in FIG. 3, by forming a second air electrode layer 16 between the air electrode layer 10 (first air electrode layer) and the solid electrolyte layer 9, the solid electrolyte constituting the fuel cell 2 is formed. Since the layer 9 and the second air electrode layer 16 can be firmly bonded, durability can be improved. In addition, long-term reliability can be improved.

In this case, the air electrode layer 10 and the second air electrode layer 16 can be made of the same material as described above. However, since the air electrode layer 10 preferably improves the air utilization characteristics, and the second air electrode layer 16 preferably increases the bonding strength with the solid electrolyte layer 9, the porosity of the air electrode layer 10 is increased. and it is made larger than the porosity of the conductive bonding material 14 and the porosity of the second cathode layer 16.

  Thereby, since the porosity of the air electrode layer 10 is larger than the porosity of the conductive bonding material 14, the bonding strength between the current collector 3 and the conductive bonding material 14 can be improved, and the air electrode layer A sufficient amount of air (oxygen-containing gas) can be introduced. Further, since the porosity of the air electrode layer 10 is larger than the porosity of the second air electrode layer 16 (that is, the porosity of the second air electrode layer 16 is small), The bonding strength with the solid electrolyte layer 9 can be increased.

  Specifically, the porosity of the air electrode layer 10 is preferably in a range larger than 40%, particularly in a range of 50 to 70%, and the conductive bonding material 14 has a smaller porosity than the air electrode layer 10. Preferably, the porosity of the second air electrode layer 16 is smaller than that of the air electrode layer 10, and preferably in the range of 30 to 40%. Can be set.

  The thickness of the air electrode layer 10 can be set to 30 to 100 μm, and the thickness of the second air electrode layer 16 can be set to 5 to 50 μm.

By the way, it is preferable that the interconnector 13 laminated on the other flat portion of the support substrate 11 on which the fuel electrode layer 8 and the solid electrolyte layer 9 are not formed is made of conductive ceramics. In order to come into contact with fuel gas (hydrogen-containing gas) and oxygen-containing gas, it is required to have reduction resistance and oxidation resistance. Therefore, it is preferable that the ceramics having reduction resistance, oxidation resistance, and conductivity have ceramics mainly composed of lanthanum chromite perovskite oxide (LaCrO ₃ oxide). . Further, in order to prevent leakage of the fuel gas passing through the inside of the support substrate 11 and the oxygen-containing gas passing through the outside of the support substrate 11, the ceramic having such conductivity is required to be dense, for example, 93% or more, In particular, it is preferable to have a relative density of 95% or more.

  Further, the thickness of the interconnector 13 is preferably 10 to 200 μm from the viewpoint of preventing gas leakage and electric resistance. If the thickness is smaller than this range, gas leakage is liable to occur. If the thickness is larger than this range, the electric resistance is large, and the current collecting function may be lowered due to a potential drop.

  Here, when the interconnector 13 and the current collector 3 are electrically connected, it is preferable that the interconnector 13 and the current collector 3 are connected via the conductive bonding material 15. As a result, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and a reduction in current collecting performance can be effectively avoided.

Here, as the conductive connecting material 15, a perovskite type oxide that can be used as the air electrode layer 10 can be used as in the conductive bonding material 14 described above, and a perovskite type having an average particle diameter of 3 μm or more. It is preferable to comprise an oxide (preferably in the range of 3 to 10 μm) and a perovskite oxide of 1 μm or less. The perovskite oxide having an average particle diameter of 3 μm or more and the perovskite oxide having an average particle diameter of 1 μm or less preferably have a mixing ratio of 7: 3 to 9: 1. Examples of the perovskite oxide include transition metal perovskite oxides, particularly LaSrCoFeO ₃ oxides (eg, LaSrCoFeO ₃ ) and LaMnO ₃ oxides in which Sr (strontium) and La (lanthanum) coexist at the A site. (For example, LaSrMnO ₃ ), LaFeO ₃ -based oxide (for example, LaSrFeO ₃ ), and LaCoO ₃ -based oxide (for example, LaSrCoO ₃ ) are preferable, and the electrical conductivity at an operating temperature of about 600 to 1000 ° C. is high. From the point of view, a LaSrCoFeO ₃ oxide is particularly preferable. In the perovskite oxide, Fe (iron) or Mn (manganese) may exist at the B site together with Co (cobalt). The thickness of the conductive bonding material 15 is preferably in the range of 30 to 100 μm.

Here, the porosity of the conductive bonding material 15 that connects the interconnector 13 and the current collecting member 3 is higher than the porosity of the conductive bonding material 14 that connects the air electrode layer 10 and the current collecting member 3 described above. not small. Thereby, the current generated by the power generation of the fuel battery cell 2 can be efficiently collected, and a cell stack with improved power generation efficiency can be obtained.

  Specifically, the porosity of the conductive bonding material 14 is smaller than the porosity of 40 to 60%, and the porosity of the conductive bonding material 15 is preferably in the range of 30 to 50%. it can.

Having described respective members constituting the fuel cell 2, followed by the manufacturing method of the fuel cell 2 (cell stack) will be described.

First, a clay is prepared by mixing an iron group metal such as Ni or its oxide powder, a rare earth oxide powder such as Y ₂ O ₃ , an organic binder, and a solvent, and using this clay A support substrate 11 molded body is prepared by extrusion molding and dried. As the support substrate 11 molded body, a calcined body obtained by calcining the support substrate 11 molded body at 900 to 1000 ° C. for 2 to 6 hours may be used.

Next, for example, ZrO ₂ (YSZ) raw material in which NiO and Y ₂ O ₃ are dissolved is weighed and mixed according to a predetermined composition. Thereafter, an organic binder and a solvent are mixed with the mixed powder to prepare a slurry for the fuel electrode layer 8.

Further, a slurry obtained by adding toluene, a binder, a commercially available dispersant, etc. to a ZrO ₂ powder in which a rare earth element is solid-solubilized is molded to a thickness of 7 to 75 μm by a method such as a doctor blade. A solid electrolyte layer 9 compact is produced. The slurry for the fuel electrode layer 8 is applied on the obtained sheet-shaped solid electrolyte layer 9 molded body to form the fuel electrode layer 8 molded body, and the surface on the fuel electrode layer 8 molded body side is used as the support substrate 11 molded body. Laminate. The fuel electrode layer 8 slurry is applied to a predetermined position of the support substrate 11 molded body and dried, and the solid electrolyte layer 9 molded body coated with the fuel electrode layer 8 slurry is laminated on the conductive support substrate 11 molded body. Also good.

Subsequently, a material for the interconnector 13 (for example, LaCrO ₃ -based oxide powder), an organic binder and a solvent are mixed to prepare a slurry, and a sheet for the interconnector 13 is prepared, and a solid electrolyte layer 9 molded body is formed. The support substrate 11 that is not laminated is laminated on the exposed surface.

  Next, the above-mentioned laminated molded body is subjected to binder removal treatment and co-fired at 1400 to 1600 ° C. for 2 to 6 hours in an oxygen-containing atmosphere.

Subsequently, when the air electrode layer 10 is formed as a single layer when the air electrode layer 10 is provided, for example, a slurry containing LaCoO ₃ oxide powder, a solvent, and a pore former is screen-printed on the solid electrolyte layer 9. After applying and drying by the method, baking is performed at 1100 to 1200 ° C. for 1 to 3 hours. In addition, as a pore making material, the thing of the fibrous form which has a magnitude | size (diameter) of 5-20 micrometers can be used, for example, and it is 20 wt% or less so that the air electrode layer 10 may become the target porosity. It can add suitably in the range.

On the other hand, when the second air electrode layer 16 is formed between the air electrode layer 10 and the solid electrolyte layer 9, first, for example, a LaSrCoFeO ₃ -based oxide powder that is a material of the second air electrode layer 16. A slurry containing a solvent and a solvent is applied onto the solid electrolyte layer 9 by a screen printing method and dried.

Subsequently, for example, a slurry containing LaSrCoFeO ₃ -based oxide powder, a solvent, and a pore forming agent, which is a material of the air electrode layer 10, is applied onto the second air electrode layer 16 molded body by a screen printing method. After drying, baking is performed at 1100 to 1200 ° C. for 1 to 3 hours. As the pore former, the aforementioned pore former can be appropriately used according to the target porosity of the air electrode layer 10 and the second air electrode layer 16. The fuel cell 2 can be manufactured through the above steps.

Subsequently, on the air electrode layer 10 and the interconnector 13 of each fuel cell 2 constituting the cell stack, the conductive joint 14 and the conductive joint 15 material (for example, LaSrCoFeO ₃ -based oxide powder), the solvent, The slurry containing is applied by screen printing.

  Immediately after coating by the screen printing method, the current collecting member 3 is adhered, dried, and baked. As a result, a cell stack in which the current collecting member 3 is interposed between the fuel cells 2 can be formed.

  In addition, it is preferable that the fuel cell 2 thereafter circulates a hydrogen-containing gas (fuel gas) therein to perform the reduction treatment of the support substrate 11 and the fuel electrode layer 8. In that case, it is preferable to perform a reduction process at 750-1000 degreeC for 5 to 20 hours, for example.

  Then, as shown in FIG. 4, the lower end of the fuel cell 2 is fixed to the manifold 6, and the current collecting member 3 is arranged from both ends in the arrangement direction of the fuel cell 2. The cell stack device 1 is manufactured by arranging the end current collecting member 4 so as to sandwich the cell stack via the gas pipe and connecting the reaction gas pipe 7 for supplying the reaction gas (fuel gas, etc.) to the manifold 6. To do.

  By storing the produced cell stack device 1 in the storage container 18, the fuel cell module 17 of the present invention can be obtained. It should be noted that a plurality of cell stack devices 1 can be arranged in the storage container 18 as necessary. In FIG. 4, a reformer 19 for supplying fuel gas to the manifold 6 is disposed above the fuel cell 2, and the cell stack apparatus 1 including the reformer 19 may be used. it can.

  In such a fuel cell module 17, a current collecting member (not shown) disposed between the fuel cells 2 constituting the cell stack can be firmly connected to the fuel cells 2, and long-term reliability is improved. Since the cell stack device 1 is stored in the storage container 18, long-term reliability can be improved.

  FIG. 5 is an exploded perspective view showing an example of the fuel cell device 20 of the present invention. In FIG. 5, a part of the configuration is omitted.

  The fuel cell device 20 shown in FIG. 5 divides the inside of an exterior case composed of a column 21 and an exterior plate 22 into upper and lower portions by a partition plate 23, and a module storage chamber 24 for storing the above-described fuel cell module 17 on the upper side. The lower side is configured as an auxiliary equipment storage chamber 25 for storing auxiliary equipment for operating the fuel cell module 17. It should be noted that auxiliary equipment stored in the auxiliary equipment storage chamber 25 is omitted.

  In addition, the partition plate 23 is provided with an air circulation port 26 for flowing the air in the auxiliary machine storage chamber 25 to the module storage chamber 24 side, and a part of the exterior plate 22 constituting the module storage chamber 24 is An exhaust port 27 for exhausting the air in the module storage chamber 24 is provided.

  In such a fuel cell device 20, as described above, the fuel cell device 17 with improved long-term reliability is configured by housing the fuel cell module 17 with improved long-term reliability in the module storage chamber 24. 20 can be set.

  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.

First, NiO powder having an average particle diameter of 0.5 μm and Y ₂ O ₃ powder having an average particle diameter of 0.9 μm are calcined and reduced, so that the volume ratio is 48% by volume for Ni and 52% by volume for Y ₂ O _3. Then, the kneaded material prepared with an organic binder and a solvent was molded by an extrusion molding method, dried and degreased to prepare a conductive support substrate 3 molded body. Sample No. In No. 1, the volume ratio of the Y ₂ O ₃ powder after calcination-reduction was 45% by volume for Ni and 55% by volume for Y ₂ O ₃ .

Next, a slurry for the fuel electrode layer 8 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. The coating layer for the fuel electrode layer 8 was formed by applying and drying by a printing method. Next, using a slurry obtained by mixing a ZrO ₂ powder (solid electrolyte layer 9 raw material powder) having a particle diameter of 0.8 μm by solid microdissolution in which 8 mol% of yttrium was dissolved, an organic binder, and a solvent, A sheet for the solid electrolyte layer 9 having a thickness of 30 μm was prepared by a doctor blade method. The sheet for the solid electrolyte layer 9 was attached on the coating layer of the fuel electrode layer 8 and dried. Sample No. In No. 3, the particle size of the ZrO ₂ powder was 1.0 μm. In No. 4, the thickness of the sheet for the solid electrolyte layer 9 was 40 μm.

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

Subsequently, the LaCrO ₃ type oxide, to prepare a slurry for the interconnector 13 of a mixture of organic binder and a solvent, which, exposed supporting substrate 11 calcined body on the solid electrolyte layer 9 calcined body is not formed And co-fired at 1510 ° C. for 3 hours in the air.

  Next, in preparing the air electrode layer 10, a mixed liquid composed of powders having respective average particle sizes shown in Table 1 and isopropyl alcohol is prepared, and the solid electrolyte layer 9 of the laminated sintered body is formed. It was applied by screen printing and dried. In addition, sample No. 2 constituted by forming the second air electrode layer 16 between the air electrode layer 10 and the solid electrolyte layer 9. 5 to 14, first, the second air electrode layer 16 is prepared as a mixed liquid composed of a powder having each average particle size shown in Table 1 and isopropyl alcohol, and the solid electrolyte layer of the laminated sintered body is prepared. The second air electrode layer 16 molded body was formed on the substrate 9 by coating and drying by screen printing. Subsequently, the air electrode layer 10 was prepared by preparing a mixed liquid composed of the powders having the respective average particle diameters shown in Table 1, isopropyl alcohol, and the pore former, and screen printing on the second air electrode layer 16. Was applied and dried to form an air electrode layer 10 molded body. Thereafter, these were fired at 1150 ° C. for 2 hours. The pore former was appropriately used so as to have the porosity of each sample shown in Table 1.

  The current collecting member 3 was connected between the five fuel cells 2 formed in this manner via conductive bonding materials 14 and 15 to produce a cell stack.

  The conductive bonding material 14 includes a powder obtained by mixing each raw material powder shown as an average particle size (large) in Table 2 with a powder obtained by mixing each raw material powder shown as an average particle size (small) at respective mixing ratios, and isopropyl. A mixed liquid composed of alcohol and pore former is applied onto the air electrode layer 10 by screen printing, and the conductive bonding material 15 is a powder of each raw material shown as an average particle size (large) in Table 2, A mixed liquid composed of powder obtained by mixing each raw material powder shown as an average particle size (small) in respective mixing ratios and isopropyl alcohol was applied onto the interconnector 13 by screen printing.

  After applying the conductive bonding material 14 and the conductive bonding material 15, a pair of plate-like contact portions for contacting the adjacent fuel cells 2 provided at a predetermined interval, and the pair of contact portions Current collecting member 3 (for example, formed by continuously forming a plurality of conductive pieces in the longitudinal direction of the fuel cell 2 having one end of one contact portion and one end of the other contact portion. The current collecting member 3) composed of a pair of connecting portions along the longitudinal direction of the fuel cell 2 and a contact portion provided so as to bridge each connecting portion is bonded and dried, and then heated to 1150 ° C. And calcined for 2 hours. In addition, the fuel gas was distribute | circulated to the fuel cell 2 after baking at 850 degreeC for 10 hours, and the reduction process was performed.

Subsequently, the fuel gas is circulated through the fuel gas passage 12 of the obtained fuel battery cell 2, the oxygen-containing gas is circulated outside the fuel battery cell 2, and the fuel battery cell 2 is 750 ° C. using an electric furnace. And a power generation test was performed under the condition of a current density of 0.3 A / cm ² .

After completion of the power generation test, the presence or absence of cracks, power generation performance, and air utilization characteristics of the conductive bonding material 14 for connecting the current collecting member 3 and the air electrode layer 10 were investigated, and Table 2 shows the results. Note that the air utilization characteristics are compared with the power generation output when the air utilization rate is 5% and the power generation output when the air utilization rate is 25%. When the air utilization rate is 25%, the one with a decrease in power generation output within 15% is regarded as good (indicated by ○ in Table 2), 1
Those that decreased more than 5% were regarded as impossible (indicated by x in Table 2). Sample No. 1-4 are reference samples.

  As shown in Table 1 and Table 2, the air electrode layer 10 is formed of a sintered body mainly composed of a perovskite complex oxide having an average particle diameter of 1.0 μm or less, and the conductive bonding material 14 is averaged. It is formed from a perovskite complex oxide having a particle size of 3 μm or more and a sintered body mainly composed of a perovskite complex oxide having an average particle size of 1 μm or less, and the porosity of the air electrode layer 10 is that of the conductive bonding material 14. Sample No. larger than the porosity. In Nos. 1 to 15, no crack was generated in the conductive bonding material 14, the power generation output was 730 mV or more, and the air utilization characteristics were also good. In addition, a second air electrode layer 16 is formed between the air electrode layer 10 and the solid electrolyte layer 9, and the porosity of the air electrode layer 10 is 50 to 70%, and the porosity of the second air electrode layer 16 is increased. Sample No. 30-40%. 5-No. No. 12 showed the result that the power generation output was 770 mV or more. Furthermore, the porosity of the conductive bonding material 14 for connecting the air electrode layer 10 and the current collecting member 3 is determined based on the porosity of the conductive bonding material 15 for connecting the current collecting member 3 and the interconnector 13. Sample no. 9-No. 12 showed a result that the power generation output was 790 mV or more.

  On the other hand, sample No. 1 in which the air electrode layer 10 is a perovskite complex oxide having an average particle diameter of 2.0 μm. In No. 16, the power generation output was 700 mV. In addition, the sample No. 1 in which the conductive bonding material 14 for connecting the air electrode layer 10 and the current collecting member 3 was formed without using a perovskite complex oxide having an average particle diameter of 1 μm or less. 17 and sample No. 1 formed without using a perovskite complex oxide having an average particle size of 3 μm or more. In 18, a crack was generated in the conductive bonding material 14. Furthermore, the sample No. 10 in which the porosity of the air electrode layer 10 is 40%. In 19, the air utilization characteristics were not possible.

BRIEF DESCRIPTION OF THE DRAWINGS An example of the cell stack apparatus which comprises the cell stack of this invention is shown, (a) is a side view, (b) is a partially expanded plan view. Se is a schematic diagram showing an example of a connection between the fuel cell and the current collecting member in Rusutakku. It is the schematic which shows another example of the connection of the fuel cell and current collection member in the cell stack of this invention. It is an external appearance perspective view which shows an example of the fuel cell module of this invention. It is a disassembled perspective view which shows an example of the fuel cell apparatus of this invention.

Explanation of symbols

2: fuel cell 3: current collecting member 9: Solid electrolyte layer 10: air electrode layer 13: interconnector, 15: electroconductive bonding material 16: second air electrode layer

Claims (5)

A conductive support surface of the substrate, the fuel electrode layer, with a solid electrolyte layer and the air electrode layer are laminated in this order, a solid oxide fuel cell comprising the fuel electrode layer and electrically connected to the interconnector The air electrode layer of one of the adjacent solid oxide fuel cells and the interconnector of the other solid oxide fuel cell are connected to each other via a conductive bonding material. A cell stack electrically connected in series by a current collecting member, wherein the air electrode layer is made of a sintered body mainly composed of a perovskite complex oxide having an average particle size of 1 μm or less, and the air electrode layer A sintered body whose main component is a perovskite type complex oxide having an average particle size of 3 μm or more and a perovskite type complex oxide having an average particle size of 1 μm or less. With Ranaru, the porosity of the air electrode layer is, the much larger than the porosity of the conductive bonding material is connected to the air electrode layer, further a between the solid electrolyte layer and the air electrode layer 2 of the air electrode layer is formed, the porosity of the air electrode layer is greater than the porosity of the porosity and the second cathode layer of the conductive bonding material to be connected to the air electrode layer Ikoto A cell stack characterized by A solid oxide fuel cell comprising an interconnector electrically stacked with a fuel electrode layer, a solid electrolyte layer, and an air electrode layer stacked in this order on the surface of a conductive support substrate The air electrode layer of one of the adjacent solid oxide fuel cells and the interconnector of the other solid oxide fuel cell are connected to each other via a conductive bonding material. A cell stack electrically connected in series by a current collecting member, wherein the air electrode layer is made of a sintered body mainly composed of a perovskite complex oxide having an average particle size of 1 μm or less, and the air electrode layer A sintered body whose main component is a perovskite type complex oxide having an average particle size of 3 μm or more and a perovskite type complex oxide having an average particle size of 1 μm or less. With Ranaru, the porosity of the air electrode layer is, the larger than the porosity of the conductive bonding material is connected to the air electrode layer, said conductive for connecting the interconnector and the current collecting member The bonding material is made of a sintered body mainly composed of a perovskite complex oxide, and the porosity of the conductive bonding material connected to the interconnector is connected to the air electrode layer. A cell stack characterized by being smaller than the porosity of the material. A second air electrode layer is formed between the air electrode layer and the solid electrolyte layer, and the porosity of the air electrode layer is a pore of the conductive bonding material connected to the air electrode layer. The cell stack according to claim 2, wherein the cell stack has a rate greater than a porosity of the second air electrode layer.
.   A fuel cell module comprising the cell stack according to any one of claims 1 to 3 housed in a housing container.   5. A fuel cell device comprising the fuel cell module according to claim 4 housed in an outer case.

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