JP4658495B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell (SOFC) using a solid electrolyte.

  Conventionally, as a cell design of a solid oxide fuel cell, a flat plate type (stack type), a cylindrical type (tube type), and the like have been proposed.

  In the flat plate-type cell, a fuel electrode and an air electrode are respectively disposed on the front and back surfaces of a plate-like electrolyte, and a plurality of cells formed in this manner are used in a state where they are stacked via separators. The separator plays the role which completely isolate | separates the fuel gas and oxidant gas which are supplied to each cell, and the gas seal is given between each cell and the separator (for example, patent document 1). However, this flat cell has a drawback in that it is vulnerable to vibration, thermal cycle, etc. because it applies a gas seal by applying pressure to the cell. Yes.

  On the other hand, a cylindrical cell has a fuel electrode and an air electrode arranged on the outer peripheral surface and inner peripheral surface of a cylindrical electrolyte, and a cylindrical vertical stripe type, a cylindrical horizontal stripe type, and the like have been proposed (for example, Patent Documents). 2). However, the cylindrical cell has an advantage of excellent gas sealing properties, but has a disadvantage that the manufacturing process is complicated and the manufacturing cost is high because the structure is more complicated than that of the flat plate cell.

  In addition, there are the following problems. In order to improve the performance of both flat and cylindrical cells, it is necessary to reduce the internal resistance by thinning the electrolyte. However, if the electrolyte is too thin, it becomes vulnerable to vibration and thermal cycles. As a result, there is a problem that vibration resistance and durability are lowered.

  For this reason, as a fuel cell that replaces the flat plate type and the cylindrical type described above, the fuel electrode and the air electrode are arranged on the same surface of the substrate made of a solid electrolyte, and power is generated by supplying a mixed gas of fuel gas and oxidant gas. A non-diaphragm solid oxide fuel cell that can be used has been proposed (for example, Patent Document 3). According to this fuel cell, since it is not necessary to separate the fuel gas and the oxidant gas, the separator and the gas seal are not required, and the structure and the manufacturing process can be greatly simplified.

In such a non-membrane type solid oxide fuel cell, oxygen ion conduction is considered to occur mainly near the surface layer of the solid electrolyte, so the distance between the fuel electrode and the air electrode is set on the same surface of the solid electrolyte. The battery performance is improved by approaching with. Therefore, it is not necessary to make the thickness of the electrolyte thinner than necessary, and it is possible to improve the weakness of the electrolyte while maintaining the battery performance.
JP-A-5-3045 (first page, FIG. 6) Japanese Patent Laid-Open No. 5-94830 (first page, FIG. 1) JP-A-8-264195 (page 2-3, FIG. 1)

  However, in the fuel cell described in Patent Document 3, an interconnector is formed across the entire opposing surfaces of the opposing electrodes between adjacent electrode bodies. For this reason, the proportion of interconnectors on the electrolyte is large, and the degree of integration on the electrolyte is not necessarily high.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a solid oxide fuel cell capable of improving battery performance by increasing the degree of integration.

A solid oxide fuel cell according to the present invention has been made to solve the above problems, and includes an electrolyte and at least one electrode body formed on one surface of the electrolyte and having a fuel electrode and an air electrode. Each electrode includes an electrode main body and a convex portion projecting from the electrode main body in the planar direction of the electrode main body, and an interconnector or a current collector is formed on the convex portion. .

  According to this configuration, since each electrode is provided with a convex portion, if an interconnector is provided in this portion, it is not necessary to form an interconnector over the entire surface of one end of the electrode as in the conventional example. . Therefore, the area where the interconnector is formed can be reduced, and the degree of electrode integration in the fuel cell can be improved.

  In addition, by providing the convex portion, when the interconnector or the current collector is connected to each electrode, the positioning can be easily performed. In particular, a structure is provided in which an interconnector or a current collector is provided on the side of the apparatus for setting the fuel cell, and when the fuel cell is set in the apparatus, the interconnector or the current collector is connected to a necessary portion of each electrode. Is advantageous. Also, positioning can be easily performed when the interconnector is formed by a printing method.

  Here, if the electrode main body of each electrode is formed in a strip shape and the convex portion protrudes from the center of the electrode main body, there are the following advantages. That is, when a convex portion is formed in the center of the electrode body, when a current collector is formed on the convex portion, the distance of movement of the electrons, that is, the distance between the current collector and the position on the electrode body farthest from the current collector Is half the length of the electrode body. Therefore, since the movement distance of electrons is half the length of the electrode body, loss during electron conduction can be reduced, and output density can be improved.

  Further, when a plurality of electrode bodies are provided, the interconnectors can be shortened by the length of the convex portions when the adjacent electrode bodies are arranged with different polarities facing the convex portions. Therefore, the loss of electronic conduction can be reduced, and the cost related to the interconnector can be reduced.

  According to the solid oxide fuel cell of the present invention, the degree of integration can be improved, and when forming an interconnector or a current collector, the positioning can be easily performed.

(First embodiment)
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 plan view of a fuel cell according to this embodiment.

  As shown in FIG. 1, the fuel cell according to the present embodiment includes a plate-like electrolyte 1 and an electrode body E disposed on one surface of the electrolyte 1. The electrode body E has a fuel electrode 3 and an air electrode 5 formed in a band shape, and these are arranged at a predetermined interval. For example, the interval is preferably 1 to 1000 μm, and more preferably 10 to 500 μm.

  Each of the electrodes 3 and 5 is formed in an L shape including electrode bodies 31 and 51 formed in a strip shape and convex portions 32 and 52 projecting from the electrode bodies 31 and 51. The electrode bodies 31 and 51 of both the electrodes 3 and 5 are arranged in parallel with the interval therebetween, and the protruding portions 32 and 52 protrude from the end portions in a direction perpendicular to the direction in which the electrode bodies 31 and 51 extend. Yes. In the present embodiment, convex portions 32 and 52 are formed at different end portions of the fuel electrode 3 and the air electrode 5. That is, in the fuel electrode 3, a convex portion 32 is formed at one end which is the lower side in FIG. 1, and in the air electrode 5, a convex portion 52 is formed at the other end 51 which is the upper side in FIG. . Current collectors 71 and 72 are formed on the convex portions 32 and 52, respectively, from which current is taken out.

Next, the material of the fuel cell configured as described above will be described. As the material of the electrolyte 1, those known as electrolytes for solid oxide fuel cells can be used. For example, ceria-based oxides such as (Ce, Sm) O ₃ , (Ce, Gd) O ₃ , ( Oxygen ion conductive ceramic materials such as La, Sr) (Ga, Mg) O _{3 and} other lanthanum galade oxides, scandium stabilized zirconia (ScSZ), yttria stabilized zirconia (YSZ) and other zirconia oxides Can be used. Since the electrolyte 1 is used as a substrate and needs a certain level of strength, the thickness is preferably, for example, 200 to 1000 μm.

  The fuel electrode 3 and the air electrode 5 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 ceramic powder material forming the fuel electrode 3, for example, a mixture of nickel and an oxygen ion conductive material can be used. The metal used at this time is not limited to nickel, and a metal that is stable in a reducing atmosphere of cobalt or a noble metal (such as platinum, ruthenium, or palladium) can be used. Examples of the oxygen ion conductive material include ceria-based oxides such as (Ce, Sm) O ₃ and (Ce, Gd) O _3, and lanthanum galades such as (La, Sr) (Ga, Mg) O _3. And oxygen ion conductive ceramic materials such as zirconia oxides such as scandium stabilized zirconia (ScSZ) and yttria stabilized zirconia (YSZ), and mixtures of such ceramic materials with nickel Preferably, the fuel electrode 5 is formed. The mixed form of the oxygen ion conductive ceramic material and nickel may be a physical mixed form or a form of powder modification to nickel. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

As the ceramic powder material forming the air electrode 5, for example, a perovskite metal oxide 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. These ceramic powders can be used alone or in a mixture of two or more.

The current collectors 31 and 51 are made of conductive metals such as Pt, Au, Ag, Ni, Cu, and SUS, or metal-based materials, or La (Cr, Mg) O ₃ , (La, Ca) CrO ₃ , (La, Sr) CrO ₃ and other conductive ceramic materials such as lanthanum and chromite can be used. One of these may be used alone, or two or more may be used in combination. May be.

  The fuel electrode 3 and the air electrode 5 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. The film thicknesses of the fuel electrode 3 and the air electrode 5 are formed so as to be 1 μm to 500 μm after sintering, but preferably 10 μm to 100 μm. The current collectors 71 and 72 are also formed by adding the above-described additives to the above-described materials.

Next, an example of a method for manufacturing the above-described fuel cell will be described. First, a plate-like electrolyte 1 made of the above-described material is prepared. Subsequently, the powder material for the fuel electrode 3 and the air electrode 5 described above is used as a main component, and an appropriate amount of a binder resin, a photosensitive polymer, an organic solvent, etc. is added to each of them and kneaded to produce a fuel electrode paste and an air electrode paste. Create each. The viscosity of each paste is preferably about 10 ³ to 10 ⁶ Pa · s so as to be compatible with the screen printing method described below. Similarly, the interconnector paste is prepared by adding an additive such as a binder resin to the above-described powder material. The viscosity of this paste is the same as that of the fuel electrode paste described above.

  Subsequently, the fuel electrode paste is applied in an L shape at a position shown in FIG. 1 on the electrolyte 1 by screen printing, and then dried and sintered at a predetermined time and temperature to form the fuel electrode 3. Next, an L-shaped air electrode paste is applied to the position facing the fuel electrode 3 on the electrolyte 1 by a screen printing method at a predetermined interval, and dried and sintered at a predetermined time and temperature. 5 is formed. Thus, the electrode body E is formed. Then, current collectors 71 and 72 are formed on convex portions 32 and 52 on each fuel electrode 3 and air electrode 5. Through the above steps, a fuel cell as shown in FIG. 1 is completed. In addition, when using a photosensitive polymer for each said paste, it is necessary to sinter after passing through a drying and exposure process.

  The fuel cell configured as described above generates power as follows. First, on one surface of the electrolyte 1 on which the electrode body E is arranged, a mixed gas of hydrogen or a fuel gas made of hydrocarbon such as methane or ethane and an oxidant gas such as air is in a high temperature state (for example, 400 to 1000 ° C). Thereby, oxygen ion conduction occurs near the surface layer of the electrolyte 1 between the fuel electrode 3 and the air electrode 5 in each electrode body E, and power generation is performed.

  As described above, in the fuel cell according to the present embodiment, since the convex portions 32 and 52 are formed on the electrodes 3 and 5, if the current collecting portions 71 and 72 are provided in this portion, as in the conventional example. There is no need to form an interconnector or a current collector over the entire surface of one end of the electrode. Therefore, the integration degree in the fuel cell can be improved.

  Further, by providing such convex portions 32 and 52, when the current collecting portions 71 and 72 are connected to the electrodes 3 and 5, the positioning can be easily performed. In the fuel cell of the present embodiment, the current collectors 71 and 72 are provided on the electrodes 3 and 5, but when the current collector is not provided, for example, an interconnector or a current collector is provided on the device side where the fuel cell is set When the fuel cell is set in the apparatus, an interconnector or a current collector can be connected to a necessary portion of each electrode. At this time, the location to be connected becomes clear, which is advantageous. Also, positioning can be easily performed when the interconnector is formed by a printing method.

(Second Embodiment)
Next, a second embodiment of the solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 2 is a plan view of the fuel cell according to the present embodiment. Unlike the first embodiment, the fuel cell according to the present embodiment has a plurality of electrode bodies. In addition, since the material which comprises the fuel cell which concerns on this embodiment is the same as that of 1st Embodiment, detailed description is abbreviate | omitted.

As shown in FIG. 2, the fuel cell according to this embodiment includes three electrode bodies E on the plate-like electrolyte 1, that is, first, second, and third electrode bodies E ₁ , E ₂ and E ₃ are provided. Each electrode body E ₁ , E ₂ , E ₃ includes a fuel electrode 3 and an air electrode 5 arranged at a predetermined interval. Each of the electrodes 3 and 5 is formed in an L shape including electrode bodies 31 and 51 formed in a strip shape and convex portions 32 and 52 protruding from the electrode bodies 31 and 51. In each of the electrode bodies E ₁ , E ₂ , E ₃ , the fuel electrode 3 is arranged on the left side of the figure and the air electrode 5 is arranged on the right side. Then, it arrange | positions in the state which convex parts oppose. More specifically, between the first electrode body E ₁ and the second electrode body E ₂ , in each electrode 3, 5, the convex portions 32, 52 are opposed to each other at one end portion on the upper side of FIG. In addition, between the second electrode body E ₂ and the third electrode body E ₃ , the convex portions 32 and 52 are similarly opposed at the other end portion on the lower side of the figure.

Adjacent electrode bodies E are connected in series by an interconnector 9. That is, the interconnector 9 is formed so as to connect the convex portions 32 and 52 facing each other in the adjacent electrode body E. Further, on the convex portions located at both ends, that is, the convex portion 32 of the fuel electrode 3 of the _first electrode body E ₁ and the convex portion 52 of the air electrode 5 of the _third electrode body E ₃ , 71 and 72 are formed. The material of the interconnector 9 can be the same as that of the current collector.

  As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained, and the following effects can be obtained. That is, in the adjacent electrode body E, the fuel electrode 3 and the air electrode 5 are arranged with the convex portions 32 and 52 facing each other, so that the interconnector 9 is shortened by the length of the convex portions 32 and 52. be able to. Therefore, the loss at the time of electronic conduction can be reduced, and the cost related to the interconnector 9 can be reduced.

By the way, in this embodiment, although each electrode 3 and 5 is formed in L shape similarly to 1st Embodiment, it can also be comprised as follows, for example. As shown in FIG. 3, in this example, the fuel electrode 3 of the first electrode body E ₁ and the air electrode 5 of the third electrode body E ₃ are formed in an L shape in the same manner as described above. However, in the electrodes facing each other between the first electrode body E ₁ and the second electrode body E ₂ and between the second electrode body E ₂ and the third electrode body E ₃ , Protrusions 32 and 52 are formed at the centers of the electrode bodies 31 and 51. Thereby, in the adjacent part of the electrode body E, the convex parts 32 and 52 are arrange | positioned so that it may mutually oppose. And the interconnector 9 is formed so that the convex parts 32 and 52 which oppose in the adjacent electrode body E may be tied.

According to the configuration described above, the following effects can be obtained. That is, since the convex portions 32 and 52 are configured to protrude from the center of the electrode bodies 31 and 51, the electron moving distance, that is, the position on the interconnector 9 and the electrode body 31 and 51 farthest from the interconnector 9. Is half the length of the electrode bodies 31 and 51. Therefore, since the movement distance of the electrons is half of the length of the electrode bodies 31 and 51, the amount of power generation can be increased, and loss during electron conduction can be reduced. In the above example, the fuel electrode 3 of the first electrode body E ₁ and the air electrode 5 of the third electrode body E ₃ are formed in an L shape. Like the electrode, it can be formed so as to have a convex portion at the center, and this makes it possible to reduce loss during electron conduction.

  As mentioned above, although 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-described embodiment, the screen printing method is used for applying each paste, but is not limited thereto, doctor blade method, spray coating method, lithography method, electrophoretic electrodeposition method, roll coating method, Other general printing methods such as a dispenser coating method, CVD, EVD, sputtering method, printing method such as transfer method, and the like can be used. Moreover, as a post-process after printing, a hydrostatic press, a hydraulic press, and other general press processes can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

Here, a fuel cell having the structure shown in FIG. 1 was prepared. As the electrolyte material, a 1 mm thick plate made of GDC (Ce _0.9 Gd _0.1 O _1.9 ) was used. Further, NiO powder (0.01 to 10 μm, average 1 μm) and SDC (Ce _0.8 Sm _0.2 O _1.9 ) powder (particle size 1 to 10 μm, average 0.1 μm) are used as the fuel electrode material at a weight ratio of 7: 3. After mixing as described above, a cellulose binder resin was mixed to prepare a fuel electrode paste. The viscosity of the fuel electrode paste was 5 × 10 ⁵ mPa · s suitable for screen printing. SSC (Sm _0.5 Sr _0.5 CoO ₃ ) powder (0.1 to 10 μm, average 3 μm) was used as an air electrode material, and a cellulose binder resin was mixed to prepare an air electrode paste. The viscosity of the air electrode paste was 5 × 10 ⁵ mPa · s suitable for screen printing as in the fuel electrode. Moreover, Au powder (0.1-5 micrometers, average particle diameter 2.5 micrometers) was mixed with cellulose-type binder resin as a material of an interconnector and an electrical power collector, and the interconnector paste and the electrical power collector paste were created. These viscosities were set to 5 × 10 ⁵ mPa · s as described above.

  Next, the fuel electrode paste was applied in an L shape on the electrolyte so as to have a width of 500 μm, a length of 7 mm, and a coating thickness of 50 μm by screen printing. And after drying for 15 minutes at 130 degreeC, it sintered at 1450 degreeC for 1 hour, and formed the fuel electrode. Subsequently, an air electrode paste is applied on the electrolyte in an L-shape so as to have a width of 500 μm, a length of 7 mm, and an application thickness of 50 μm so as to be aligned with each fuel electrode, and the air electrodes are adjacent to each other. I did it. At this time, the positional relationship between the fuel electrode and the air electrode was as shown in FIG. 1, and the interval was 200 μm. And after drying for 15 minutes at 130 degreeC, it sintered at 1200 degreeC for 1 hour, and formed the air electrode. Next, a paste containing Au as a main component was applied to the convex portions of the fuel electrode and the air electrode to form a current collector. Thus, the fuel cell according to the example was formed.

1 is a plan view of a first embodiment of a solid oxide fuel cell according to the present invention. It is a top view of 2nd Embodiment of the solid oxide fuel cell which concerns on this invention. It is a top view which shows the modification of 2nd Embodiment of the solid oxide fuel cell which concerns on this invention.

Explanation of symbols

1 Electrolyte 3 Fuel Electrode 5 Air Electrode 7 Current Collector 9 Interconnector

Claims (4)

Electrolyte,
Comprising at least one electrode body formed on one surface of the electrolyte and having a fuel electrode and an air electrode;
Each of the electrodes includes an electrode body and a convex portion protruding from the electrode body in the plane direction of the electrode body ,
A solid oxide fuel cell , wherein an interconnector or a current collector is formed on the convex portion . The electrode body of each electrode is formed in a strip shape,
The solid oxide fuel cell according to claim 1, wherein the convex portion projects from a center of the electrode body. A plurality of the electrode bodies are provided,
3. The solid oxide fuel cell according to claim 1, wherein, in adjacent electrode bodies, different polarities are arranged in a state where the convex portions are opposed to each other. The solid oxide fuel cell according to claim 3 , wherein the opposing convex portions are connected via an interconnector.

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