JP5205731B2 - Solid oxide fuel cell and stack structure thereof - Google Patents

Description

  The present invention relates to a solid oxide fuel cell operating with a fuel gas and an oxidant gas and a stack structure thereof.

A fuel cell is a cell that can directly convert chemical energy generated when fuel is oxidized into electric energy while continuously supplying fuel from the outside and exhausting combustion products. The types of fuel cells are classified according to the electrolyte, and those using a solid oxide having ionic conductivity for the electrolyte are called solid oxide fuel cells. Various types of solid oxide fuel cells have been proposed. For example, Patent Document 1 discloses a single-chamber solid oxide type in which a fuel electrode and an air electrode are formed on both sides of a solid electrolyte. A fuel cell is disclosed.
JP 2002-352846 A

  By the way, in the fuel cell in which the fuel electrode and the air electrode are respectively formed on both surfaces of the electrolyte as in Patent Document 1, the electrolyte is often configured as a support substrate in order to improve the strength. In this case, the thickness of the electrolyte needs to be increased to some extent in order to maintain the strength, and thus there is a problem that high output cannot be expected.

  Therefore, an object of the present invention is to provide a solid oxide fuel cell and a stack structure thereof that can improve output even if the electrolyte is thinned.

The present invention has been made to solve the above problems, and includes a plurality of single cells each having a thin film fuel electrode, an air electrode, and a thin film electrolyte disposed therebetween, and the plurality of the plurality of single cells. A plurality of single cells stacked such that the fuel electrode and the air electrode face each other, and the interconnector is connected to the adjacent single cells. is inserted between, wherein the plurality of single cells and the interconnector, at least one through-hole extending therethrough is formed in the stacking direction, moreover state, and are the 500μm or more total thickness of the stacking direction, The interconnector has a thickness of 5 to 50 μm. Alternatively, a plurality of single cells each having a thin film fuel electrode, an air electrode, and a thin film electrolyte disposed therebetween, and a thin film interconnector connecting the plurality of single cells in series. The plurality of single cells are stacked such that the fuel electrode and the air electrode face each other, and the interconnector is interposed between the adjacent single cells. The connector has at least one through-hole penetrating therethrough in the laminating direction, and the total thickness in the laminating direction is 500 μm or more, and the thickness of the fuel electrode and the air electrode is 20 to 50 μm. .

  According to this configuration, a plurality of single cells each made of a fuel electrode, an air electrode, and an electrolyte are thinned through an interconnector, and the total thickness is 500 μm or more. The strength can be ensured by the thickness. Thereby, the crack of the single cell by the vibration at the time of production of a cell at the time of printing an electrode, stacking, or operation, etc. can be prevented. Therefore, since the electrolyte can be thinned while ensuring the strength, the output of the battery can be improved. Further, since this battery has a plurality of laminated single cells, it is possible to obtain a high output with a small capacity. Since both electrodes, electrolyte, and interconnector have through-holes in the stacking direction, if gas is supplied to these through-holes, gas is distributed to both electrodes. There is no problem.

Also, the thickness of the electrolyte is preferably 50 to 200 [mu] m.

The fuel electrode, air electrode, electrolyte, and interconnector can be formed by various methods. For example, the electrode can be formed by sintering a green body.

  According to the solid oxide fuel cell of the present invention, a high output can be obtained with a small capacity without degrading the strength even if the electrolyte is made thin.

  Hereinafter, an embodiment of a solid oxide fuel cell according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a solid oxide fuel cell according to this embodiment.

  As shown in FIG. 1, the solid oxide fuel cell according to this embodiment includes a single cell 1 having a rectangular shape in a plan view in which a thin film fuel electrode 12, an electrolyte 11, and an air electrode 13 are stacked in this order. A battery is formed by stacking a plurality of single cells 1 via interconnectors 2 (two in FIG. 1). The interconnector 2 is formed in a thin film shape having a rectangular shape in plan view like the single cell 1 and is disposed so as to electrically connect the air electrode 13 and the fuel electrode 12 of the single cell 1 adjacent in the vertical direction. . In the battery formed in this way, a plurality of through holes 3 penetrating each single cell 1 and interconnector 2 are formed in the stacking direction.

  The thickness T in the stacking direction of the battery is 500 μm or more. The thickness of each member is preferably as follows. That is, it is preferable that the thickness of the fuel electrode 12 and the air electrode 13 is 20-50 micrometers, for example. This is because if it is 20 μm or more, it is easy to secure a reaction field with the gas, and if it is 50 μm or less, the gas diffusibility can be maintained. The thickness of the electrolyte 11 is preferably as thin as possible from the viewpoint of shortening the distance of oxygen ion conduction, but is preferably 50 to 200 μm, for example. Moreover, it is preferable that the thickness of the interconnector 2 is 5-50 micrometers.

  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 oxide doped with samarium or gadolinium, lanthanum galade doped with strontium or magnesium, etc. 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 above materials, it is preferable to form the fuel electrode 2 with 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.

In addition, the interconnector 2 is made of conductive metal such as Pt, Au, Ag, Ni, Cu, SUS, or a metal material, or La (Cr, Mg) O ₃ , (La, Ca) CrO ₃ , (La, It can be formed of a lanthanum chromite-based conductive ceramic material such as Sr) CrO _3, and one of these may be used alone, or two or more may be used in combination. Good.

  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. Similarly to the fuel electrode 12 and the air electrode 13, the electrolyte 11 is molded by adding an appropriate amount of a binder resin, an organic solvent, or the like with the above-described material as a main component. In the mixing, it is preferable to mix so that the ratio of the main component is 80% by weight or more. Furthermore, the interconnector 2 is also formed by adding the above additive to the above-described material.

  Next, the fuel cell manufacturing method described above will be described with reference to FIG. First, the fuel electrode and air electrode preparation materials described above are mixed with a binder, a solvent, a plasticizer, a dispersant, and a foaming agent, dispersed in a ball mill, and then subjected to vacuum degassing to produce a fuel electrode paste and an air electrode paste. . Next, a binder, a solvent, a plasticizer, and a dispersant are mixed with the electrolyte and interconnector material, and then dispersed in a ball mill in the same manner as described above, followed by vacuum evacuation to prepare an electrolyte paste and an interconnector paste. . Each of these pastes is dried on a polyethylene terephthalate (PET) film coated with a release layer, then printed with a doctor blade so as to have a predetermined film thickness, and dried at 120 ° C. to thereby prepare a fuel on the PET film. Form green bodies for electrodes, air electrodes, electrolytes, and interconnectors.

  Subsequently, the green body for the fuel electrode and the green body for the electrolyte are bonded together and hot pressed to fuse the green bodies together, and then the PET film of the green body for the electrolyte is peeled off. The green body for an air electrode is bonded to the thus exposed green body for an electrolyte and fused by hot press, and then the PET film of the green body for an air electrode is peeled off. Subsequently, the interconnector green body is laminated in the same manner. Subsequently, the lamination of the fuel electrode, the electrolyte, the air electrode, and the green body for the interconnector is repeated to produce a laminate as shown in FIG.

  Subsequent to this, the laminated body is punched at a plurality of locations in the laminating direction to form the through holes 3 and then sintered at 1100 to 1500 ° C., thereby completing the fuel cell according to the present embodiment. At this time, since the green body for the fuel electrode and the green body for the air electrode contain a foaming agent, the fuel electrode 12 and the air electrode 13 can be made porous by sintering as described above.

  The fuel cell configured as described above generates power as follows. First, a mixed gas of a fuel gas composed of hydrogen or a hydrocarbon such as methane or ethane and an oxidant gas such as air is supplied to the battery at a high temperature (for example, 400 to 1000 ° C.). At this time, the mixed gas is supplied from one opening of the through hole 3. Thereby, since the mixed gas comes into contact with the fuel electrode 12 and the air electrode 13 through the through-hole 3, oxygen ion conduction through the electrolyte 11 occurs between the fuel electrode 12 and the air electrode 13, and power generation occurs. Done. The mixed gas is discharged from the other opening of the through-hole 3 and also from the edges of the fuel electrode 12 and the air electrode 13 formed as porous. That is, it passes through both electrodes 12 and 13 radially from the through hole 3 and is discharged to the outside of the battery.

  As described above, according to the present embodiment, a plurality of unit cells 1 in which all of the fuel electrode 12, the air electrode 13, and the electrolyte 11 are thinned are stacked via the interconnector 2, and the total thickness is 500 μm or more. Therefore, even if the electrolyte 11 is thinned, the strength can be ensured by the entire thickness. That is, even if individual members are thinned, the overall thickness is 500 μm or more, so that the strength as a battery can be maintained. Therefore, since the electrolyte 11 can be made thin while ensuring the strength, the output of the battery can be improved. In addition, since the battery is provided with a plurality of thinned single cells 1, it is possible to obtain a high output with a small capacity.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention. In the above embodiment, all the layers are formed of a green body, but it is also possible to print a part of the layers on the green body and to laminate the green body on the printed surface. In addition, although the two single cells 1 are overlapped via the interconnector 2, the present invention is not limited to this, and three or more single cells 1 may be overlapped. That is, if the total thickness is 500 μm or more, the number of single cells and the thicknesses of the fuel electrode 12, the air electrode 13, the electrolyte 11 and the interconnector 2 constituting the single cell may be thin films as described above. For example, there is no particular limitation.

  Further, the number and shape of the through holes 3 are not particularly limited as long as the gas can contact each electrode without reducing the reaction field.

  Moreover, the production method of the fuel cell according to the present invention is not limited to the above, and can be formed by, for example, powder press molding. More specifically, a binder, a solvent, a release agent, a lubricant, and the like are added to the raw material powder for the fuel electrode, air electrode, electrolyte, and interconnector, and stirring and defoaming are performed. Thereafter, drying, pulverization, and sieving are performed to produce granules for each member. Subsequently, a foaming agent is mixed in the granules for electrodes, and the prepared granules are filled in the mold. That is, the granules are repeatedly filled in the mold so as to have a desired layer structure in the order of the interconnector, the fuel electrode, the electrolyte, and the air electrode, press-molded, and fired. In this way, after the laminated body as described above is manufactured, if the through hole is formed, the fuel cell as described above is completed. The through hole is formed by using a general method such as blasting.

  Examples according to the present invention will be described below. However, the present invention is not limited to the following examples.

  A single cell was prepared from the materials shown below, and this was laminated via an interconnector, and Examples and Comparative Examples shown in Table 1 were prepared.

Plane dimensions: 10x10mm
Number of through holes: 4 Through hole diameter: 1 mm
Electrolyte material: Ce _0.9 Gd _0.1 O _1.9 (GDC)
Fuel electrode material: NiO-Ce _0.8 Sm _0.2 O _1.9 (SDC)
Air electrode material: Sm _0.5 Sr _0.5 CoO ₃
Interconnector material: Au

上記のような実施例及び比較例をそれぞれ５個ずつ準備し、貫通孔を設けたＳＵＳの集電板（厚さ２ｍｍ）で挟みこみ、発電をさせた後、各セルの状態を観察した。結果は、以下の通りである。

Five examples and comparative examples as described above were prepared, sandwiched between SUS current collector plates (thickness 2 mm) provided with through holes, and after power generation, the state of each cell was observed. The results are as follows.

以上の結果より、合計厚さは、５００μｍ以上であることが好ましいことがわかる。

From the above results, it is understood that the total thickness is preferably 500 μm or more.

1 is a perspective view showing an embodiment of a solid oxide fuel cell according to the present invention.

Explanation of symbols

1 Single cell 11 Electrolyte 12 Fuel electrode 13 Air electrode 2 Interconnector 3 Through hole

Claims (4)

It has a plurality of single cells consisting of a thin-film fuel electrode, an air electrode, and a thin-film electrolyte disposed therebetween,
A thin film interconnector for connecting the plurality of single cells in series,
The plurality of single cells are stacked such that the fuel electrode and the air electrode face each other, and the interconnector is interposed between the adjacent single cells,
The plurality of single cells and the interconnector, with at least one through hole extending therethrough is formed in the stacking direction state, and are the 500μm or more total thickness of the stacking direction,
A solid oxide fuel cell , wherein the interconnector has a thickness of 5 to 50 μm . It has a plurality of single cells consisting of a thin-film fuel electrode, an air electrode, and a thin-film electrolyte disposed therebetween,
A thin film interconnector for connecting the plurality of single cells in series,
The plurality of single cells are stacked such that the fuel electrode and the air electrode face each other, and the interconnector is interposed between the adjacent single cells,
The plurality of single cells and the interconnector, with at least one through hole extending therethrough is formed in the stacking direction state, and are the 500μm or more total thickness of the stacking direction,
The thickness of the said fuel electrode and an air electrode is a solid oxide fuel cell whose thickness is 20-50 micrometers .   3. The solid oxide fuel cell according to claim 1, wherein the electrolyte has a thickness of 50 to 200 μm. 4. The solid oxide fuel cell according to claim 1 , wherein the fuel electrode, the air electrode, the electrolyte, and the interconnector are formed by sintering a green body. 5.

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