JP2007273422A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell allowing easily stacking of two or more unit cells. <P>SOLUTION: The solid oxide fuel cell to which a mixture of fuel gas and oxidant gas is supplied is equipped with the unit cell 1 having a fuel electrode 12 and an air electrode 13 on each side of a sheet-shaped electrolyte 11; and a substrate 2 supporting the unit cell 1 and conductive and porous, A region 4 adjoined to the unit cell 1 in the substrate 2 has a larger area than the unit cell 1 as viewed from above. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell that generates power using a mixed gas of a fuel gas and an oxidant gas.

In recent years, a single-chamber SOFC has been proposed in which a gas supply line can be simplified and a simple system structure can be realized without using a separator or a gas seal material by mixing and supplying fuel gas and oxidant gas. Yes. The fuel cell employed in this single-chamber SOFC has two electrodes, a fuel electrode and an air electrode, which are exposed to a mixed gas of fuel gas and oxidant gas, and have gas selectivity between them. Is characterized by the generation of voltage. As a battery structure, for example, as shown in Patent Document 1, there is a cell structure in which a fuel electrode is disposed on one surface of an electrolyte substrate and an air electrode is disposed on the other surface.
JP 2002-50370 A

  By the way, in order to obtain a desired output, a plurality of fuel cells as described above are often used in a stack. However, since the number of unit cells to be stacked varies depending on the required output, there has been a demand for a single cell structure that can be easily stacked according to the output required from time to time.

  The present invention has been made to solve the above problems, and an object thereof is to provide a solid oxide fuel cell capable of easily stacking a plurality of single cells.

  The present invention is a solid oxide fuel cell to which a mixed gas of a fuel gas and an oxidant gas is supplied, and has been made in order to solve the above-described problem, and is a mixture of a fuel gas and an oxidant gas. A solid oxide fuel cell to which a gas is supplied, a single cell having a fuel electrode and an air electrode formed on both sides of a sheet-like electrolyte, and supporting the single cell, and having conductivity and porosity A region adjacent to the single cell in the substrate has an area larger than that of the single cell in plan view.

  According to this configuration, since a region having a larger area than the single cell is formed in a region adjacent to the single cell on the substrate, a plurality of batteries can be easily stacked. For example, when stacking two batteries, one battery is arranged so that the single cell faces upward, and the other battery is inverted so that the single cell faces downward. And it fixes so that the single cell of the other battery may contact | abut on the said area | region of one battery. That is, when each battery has the above-described configuration, it can be stacked in the surface direction of the substrate while the directions of the plurality of single cells are staggered. Since the substrate has conductivity, the single cells can be connected in series by connecting as described above. Therefore, if a plurality of fuel cells having the above configuration are prepared, a desired number of cells can be easily stacked according to the required output. The sheet form includes not only a thin film form but also a hard plate form.

  Here, it is preferable that a concave portion larger than the single cell is formed in the region in plan view. According to this configuration, when connecting the batteries, the single cell of the other battery can be disposed in the recess of the one battery, so that the thickness of the stacked batteries can be reduced. At this time, if the depth of the region is larger than the thickness of the single cell, the single cell enters the recess, so that the thickness of the stacked battery can be reduced by the thickness of the single cell, and the compact Can be achieved.

  According to the solid oxide fuel cell of the present invention, a plurality of single cells can be easily stacked.

  Hereinafter, an embodiment of a solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a solid oxide fuel cell according to this embodiment, and FIG. 2 is a plan view of FIG.

  As shown in FIG. 1, the solid oxide fuel cell according to this embodiment includes a single cell 1 having an electrolyte 11, a fuel electrode 12, and an air electrode 13, and a substrate 2 that supports the cell. The single cell 1 is configured by forming a thin film fuel electrode 12 and an air electrode 13 on both surfaces of a sheet-like electrolyte 11. The single cell 1 is fixed so that the fuel electrode 12 contacts the substrate 2. In the present embodiment, the periphery of the fuel electrode 12 is fixed to the substrate 2 by the glass seal 3. The substrate 2 is formed in a rectangular shape having conductivity and porosity. As shown in FIGS. 1 and 2, the single cell 1 is disposed on the left side of the substrate 2, and a region 4 in which nothing larger than the single cell 1 is disposed is secured on the right side. In this region 4, as will be described later, the single cells 1 of other batteries are arranged. Hereinafter, this area is referred to as a “connection area”.

  Next, materials constituting the fuel cell will be described. As the material of the electrolyte 11, those known as electrolytes for solid oxide fuel cells can be used. For example, ceria-based oxides doped with samarium or gadolinium, lanthanum galade-based doped with strontium or magnesium Oxygen ion conductive ceramic materials such as oxides, zirconia-based oxides containing scandium and yttrium can be used.

  The fuel electrode 12 and the air electrode 13 can be formed of a ceramic powder material. The average particle size of the powder used at this time is preferably 10 nm to 100 μm, more preferably 50 nm to 50 μm, and particularly preferably 100 nm to 10 μm. In addition, an average particle diameter can be measured according to JISZ8901, for example.

  As the fuel electrode 12, for example, a mixture of a metal catalyst and a ceramic powder material made of an oxide ion conductor can be used. As the metal catalyst used at this time, a material that is stable in a reducing atmosphere, such as nickel, iron, cobalt, or a noble metal (platinum, ruthenium, palladium, etc.) and has hydrogen oxidation activity can be used. In addition, as the oxide ion conductor, one having a fluorite structure or a perovskite structure can be preferably used. Examples of those having a fluorite structure include ceria-based oxides doped with samarium, gadolinium, and the like, and zirconia-based oxides containing scandium and yttrium. In addition, examples of those having a perovskite structure include lanthanum galide oxides doped with strontium and magnesium. Among the materials described above, the fuel electrode 12 is preferably formed of a mixture of an oxide ion conductor and nickel. The mixed form of the ceramic material made of the oxide ion conductor and nickel may be a physical mixed form, or may be a powder modification to nickel or a nickel modification to ceramic material. Good. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types. Further, the fuel electrode 12 can also be configured using a metal catalyst alone.

As the ceramic powder material forming the air electrode 13, for example, a metal oxide made of Co, Fe, Ni, Cr, Mn or the like having a perovskite structure or the like can be used. Specifically, (Sm, Sr) CoO ₃ , (La, Sr) MnO ₃ , (La, Sr) CoO ₃ , (La, Sr) (Fe, Co) O ₃ , (La, Sr) (Fe, Co , Ni) O _{3 and the} like, and (La, Sr) (Fe, Co) O ₃ is preferable. The ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

  The electrolyte 11, the fuel electrode 12, and the air electrode 13 are formed by adding appropriate amounts of a binder resin, an organic solvent, and the like with the above-described material as a main component. More specifically, it is preferable to add a binder resin or the like so that the main component is 50 to 95% by weight in the mixing of the main component and the binder resin.

  As a method for forming the electrolyte 11, the fuel electrode 12, and the air electrode 13, for example, a printing method can be used. Specifically, a printing method such as a screen printing method, a knife coating method, a doctor blade method, or a spray coating is used. Can be used. In addition to this, the electrolyte 11, the fuel electrode 12, and the air electrode 13 can be applied on a transfer sheet (so-called green body), and these can be transferred to form an electrode.

The substrate 2 has electronic conductivity, but it is preferable that the ion conductivity is small enough to be ignored. Moreover, it is preferable to be comprised with the thermodynamically stable material. The conductivity is preferably 2 S · cm ⁻¹ or more at the operating temperature of the fuel cell. While satisfying such requirements, each layer can be configured as follows. The porosity of the substrate is preferably in the range of 10 to 80% in consideration of gas permeability and the strength of the substrate. In order to satisfy such requirements, the material constituting the substrate 2 is a conductive metal such as Pt, Au, Ag, Ni, Cu, SUS, or a metal-based material, or La (Cr, Mg) O ₃ , (La , Ca) CrO ₃ , (La, Sr) CrO ₃ and other conductive ceramic materials such as lanthanum and chromite, and one of these may be used alone or two You may mix and use the above.

  Next, stacking of the fuel cells configured as described above will be described. FIG. 3 is a cross-sectional view of a plurality of stacked batteries. As shown in FIG. 3, when two batteries are connected, first, the single cell 1 is arranged so as to face upward in one battery, and the other battery faces the single cell 1 downward. And the other single cell 1 is fixed to the connection area | region 4 adjacent to the single cell 1 of one battery with a glass seal. Similarly, next, the battery with the single cell 1 facing upward is fixed to the connection region 4 of the other battery, and when this is repeated for a plurality of batteries, a plurality of batteries are stacked so as to extend in the plane direction. Can be

  The fuel cell configured as described above generates power as follows. First, a mixed gas of hydrogen or a fuel gas composed of a hydrocarbon such as methane or ethane and an oxidant gas such as air is supplied at a high temperature (for example, 400 to 1000 ° C.). Since the substrate 2 is porous, the mixed gas flows into the substrate 2 and comes into contact with the electrodes 12 and 13. Thus, since the fuel electrode 12 and the air electrode 13 are in contact with the mixed gas, oxygen ion conduction through the electrolyte 11 occurs between the fuel electrode 12 and the air electrode 13 in each unit cell 1 to generate power. .

  As described above, according to this embodiment, since the connection region 4 is formed adjacent to the single cell 1, the single cell 1 of another battery can be inverted and attached to the connection region 4. In this way, since a plurality of batteries can be connected while being staggered, stacking can be easily performed. Therefore, if a plurality of fuel cells having the above configuration are prepared, a desired number of cells can be easily stacked according to the required output.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A various change is possible unless it deviates from the meaning. For example, in the above embodiment, the thickness D of the stacked batteries is the thickness of the two substrates 2 plus the thickness of the single cell. Here, if the concave portion is formed in the connection region 4 and the single cell is accommodated therein, the thickness of the battery can be further reduced. As shown in FIG. 4, if the depth of the recess 21 is the same as the total thickness of the electrolyte 11 and the air electrode 13, and a glass seal 3 having a thickness similar to that of the fuel electrode 12 is provided around the single cell 1, The thickness of the battery can be reduced by the total thickness of the electrolyte 11 and the air electrode 13. Alternatively, the recess 21 deeper than this can be formed, but it is necessary to contact the air electrode 13 and the recess wall surface or to provide a conductive member between them so as to be electrically connected.

  In addition, the fixing of the single cell and the connection between the batteries can be performed other than the glass seal, and for example, an insulating adhesive can be applied.

1 is a cross-sectional view showing an embodiment of a solid oxide fuel cell according to the present invention. It is a top view of FIG. It is a cross section when the solid oxide fuel cell according to FIG. 1 is stacked. It is sectional drawing which shows the other example of the solid oxide fuel cell which concerns on this invention.

Explanation of symbols

1 single cell 11 electrolyte 12 fuel electrode 13 air electrode 2 substrate 21 recess

Claims (2)

A solid oxide fuel cell to which a mixed gas of a fuel gas and an oxidant gas is supplied,
A single cell in which a fuel electrode and an air electrode are formed on both sides of a sheet-like electrolyte, and
And supporting the single cell, and having a conductive and porous substrate,
A region of the substrate adjacent to the single cell has a larger area than the single cell in plan view. 2. The solid oxide fuel cell according to claim 1, wherein a concave portion larger than the single cell is formed in the region in plan view.

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