JPH1012247A - Solid electrolyte fuel cell and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a power generation characteristic of a fuel cell by eliminating generation of pores since an electrode material does not spread over the vicinity of material grains of a solid electrolyte, and expanding the effective electrode area by reliably roughening a contact interface in roughening an interface between a solid electrolyte layer and an electrode. SOLUTION: This fuel cell has an electrolyte 1 where electrodes 2 are arranged on the obverse and reverse, and electrode material grains 6 are arranged on a contact plane 3 between the solid electrolyte 1 and the electrodes 2, and the electrode material grains 6 are respectively embedded deeper in the solid electrolyte 1 side than the electrode 2 side. As its manufacturing method, a fuel electrode material grain is stuck to one of a mold surface for the solid electrolyte, and an air electrode material grain is stuck to the other, respectively, and these are sandwiched and press-bonded from both surfaces, and these electrode material grains are made to bite in the mold surface for the solid electrolyte, and a mold for a fuel electrode is arranged in one of this mold surface for the solid electrolyte, and a mold for an air electrode is arranged in the other, respectively, and these are laminated, and this is press-bonded, and is baked as a laminated mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid oxide fuel cell and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a solid oxide fuel cell, each layer of a fuel electrode, a solid electrolyte layer and an air electrode is arranged on each other and laminated to form three layers. It supplies fuel gas and supplies air to the air electrode to generate electricity. The air electrode may be referred to as an oxygen electrode and oxygen gas may be supplied thereto.

[0003]

In order to improve the power generation characteristics of the solid oxide fuel cell, the area of the three-phase interface composed of the fuel electrode, the air electrode, the solid electrolyte, and the gas phase is increased as much as possible. It is necessary.

In order to increase the area of the three-phase interface, there is an invention in which the contact interface between the solid electrolyte and each electrode is roughened to improve the power generation characteristics. For example, in Japanese Patent Application Laid-Open No. 7-73890, after a material particle of a solid electrolyte having an average particle diameter of about 10 μm is attached to the front and back surfaces of a ceramic green sheet for a solid electrolyte, the ceramic green sheet for each electrode of a fuel electrode and an air electrode is provided. Are superimposed on the front and back surfaces of the ceramic green sheet for solid electrolyte, respectively, and are pressed to roughen the contact interface between the solid electrolyte and each electrode to increase the effective electrode area.

However, in this method, the contact interface between the solid electrolyte and each electrode has not been sufficiently roughened. That is, when the solid electrolyte particles are attached to the surface of the ceramic green sheet for solid electrolyte and the green sheet for electrode is pressed on this surface, the contact interface 3 between the solid electrolyte 1 and the electrode 2 as shown in the sectional view of FIG. However, the electrode material does not spread in the vicinity of the solid electrolyte particles 4, and as a result, pores 5 are formed,
The contact area between the solid electrolyte 1 and the electrode 2 has decreased.
The reduction in the contact area between the solid electrolyte and the electrode as described above causes a problem that the power generation characteristics of the solid oxide fuel cell cannot be sufficiently improved.

Accordingly, an object of the present invention is to roughen the contact interface between the solid electrolyte and the electrode, and to prevent the electrode material from spreading to the vicinity of the material particles of the solid electrolyte used for the roughening so that pores are formed. It is an object of the present invention to provide a solid oxide fuel cell capable of preventing the occurrence of the solid electrolyte, reliably roughening the contact interface, increasing the effective electrode area, and improving the power generation characteristics of the battery, and a method for manufacturing the same.

[0007]

According to the present invention, there is provided a solid electrolyte fuel cell according to claim 1, comprising a solid electrolyte having electrodes provided on the front and back surfaces, and an electrode material particle formed on a joint surface between the solid electrolyte and the electrode. And the electrode material particles are buried deeper on the solid electrolyte side than on the electrode side.

The solid electrolyte fuel cell according to claim 2, further comprising a solid electrolyte provided with electrodes on the front and back surfaces, wherein solid electrolyte material particles are provided on a joint surface between the solid electrolyte and the electrode. The solid electrolyte material particles are buried deeper on the electrode side than on the solid electrolyte side.

According to a third aspect of the present invention, there is provided a method for manufacturing a solid oxide fuel cell, comprising: attaching a fuel electrode material particle to one of the surfaces of a ceramic molded body for a solid electrolyte; The ceramic material for an anode is sandwiched and pressed from both sides to cause the fuel electrode material particles and the air electrode material particles to bite into the surface of the ceramic material for a solid electrolyte. A ceramic molded body is characterized by arranging a ceramic molded body for an air electrode on the other side and laminating the laminated bodies, pressing them together to form a laminated molded body, and firing the laminated molded body.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a solid oxide fuel cell, wherein solid electrolyte material particles are adhered to a surface of a fuel electrode ceramic molded body or an air electrode ceramic molded body, and the fuel electrode ceramic molded body is formed. Alternatively, the ceramic electrolyte for the air electrode is sandwiched from both sides and pressed to cause the solid electrolyte material particles to bite into the surface of the ceramic molding for the fuel electrode or the ceramic electrode for the air electrode, and the fuel electrode further cut into the solid electrolyte material particles. The surface of the ceramic compact for air electrode or the ceramic compact for the air electrode is arranged on the surface of the ceramic compact for the solid electrolyte and laminated, and then pressed to form a laminated compact, and the laminated compact is fired. I do.

As described above, in the solid oxide fuel cell according to the present invention, the electrode material particles are disposed on the joint surface between the solid electrolyte and the electrode, and each of the electrode material particles is buried deeper in the solid electrolyte than in the electrode. Alternatively, solid electrolyte material particles are provided on the joint surface between the solid electrolyte and the electrode, and the solid electrolyte material particles are buried deeper in the electrode side than in the solid electrolyte side. For this reason, when the solid electrolyte material particles adhere to the surface of the solid electrolyte and exist on the joint surface with the electrode as in the related art, the electrode material does not spread in the vicinity of the electrode material particles, and pores are not generated. Therefore, the joint surface between the solid electrolyte and the electrode is sufficiently roughened, the contact interface between the solid electrolyte and the electrode is further enlarged, and the effective electrode area at the three-layer interface can be reliably increased. Thereby, the power generation characteristics of the solid oxide fuel cell can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a solid oxide fuel cell according to the present invention and a method for manufacturing the same will be described below.

(Example 1) In this example, the electrode material particles are cut into the surface of the ceramic molded body for a solid electrolyte to roughen the interface between the electrode and the solid electrolyte.

First, a method for producing a ceramic green sheet for a solid electrolyte, which is a ceramic molded body for a solid electrolyte, will be described.

Powdered yttria-stabilized zirconia (Y
A predetermined amount of a binder (for example, a polyvinyl butyral-based binder) and a solvent (ethanol and toluene) are added to and mixed with SZ) to form a slurry, which is then formed into a ceramic molded body having a thickness of about 80 μm by a doctor blade method.
A ceramic green sheet for a solid electrolyte was prepared.

A plurality of the ceramic green sheets for a solid electrolyte are stacked to form a laminate of the ceramic green sheets for a solid electrolyte, and a fuel electrode material particle of NiO having an average particle diameter of 10 μm is formed on a surface of the laminate in contact with the fuel electrode. The surface of the side in contact with the air electrode also has an average particle size of 10 μm (L
(a, Sr) Air electrode material particles of MnO ₃ were adhered.

Then, the laminate of the ceramic green sheets for solid electrolyte to which the electrode material particles are attached is flattened from the respective surfaces to which the electrode material particles of NiO and (La, Sr) MnO ₃ are attached. After being sandwiched between plastic films and put in a plastic bag, the inside of the bag was evacuated and pressed using a warm isostatic press.

FIG. 2 shows a cross section of the surface portion of the laminate of the ceramic green sheets for a solid electrolyte at this time.

As can be seen, the electrode material particles 6 of NiO or (La, Sr) MnO ₃ adhering to the surface of the solid electrolyte 1 enter the solid electrolyte 1 so as to bite from the surface of the solid electrolyte, and form a ceramic green sheet for the solid electrolyte. The surface of the molded article was roughened.

On the other hand, in order to produce a fuel electrode, a predetermined amount of a binder (for example, a polyvinyl butyral-based binder) and a solvent (ethanol and toluene) are added to a mixture of powdered nickel oxide and yttria-stabilized zirconia. Then, after this was made into a nickel-zirconia cermet-based slurry, a ceramic green sheet for an anode having a thickness of about 80 μm was produced as a ceramic molded body for an anode by a doctor blade method.

On the other hand, in order to produce an air electrode, predetermined amounts of a binder (for example, polyvinyl butyral-based binder) and a solvent (ethanol and toluene) are added to powdery lanthanum strontium manganite and mixed. Was made into a slurry, and an air electrode ceramic green sheet having a thickness of about 80 μm was produced as a ceramic body for an air electrode by a doctor blade method.

Each of the obtained ceramic green sheets for the fuel electrode and the air electrode is placed on the surface of the laminate of the ceramic green sheets for a solid electrolyte, that is, the surface of the solid electrolyte roughened by the fuel electrode material. The ceramic green sheet for air electrode and the ceramic green sheet for air electrode are layered on the surface of the solid electrolyte roughened by the air electrode material, placed in a plastic bag, and the inside of the bag is evacuated. Then, pressure bonding was performed using a warm isostatic press to obtain a three-layer film ceramic laminate formed of a fuel electrode, a solid electrolyte membrane, and an air electrode.

As shown in the cross-sectional view of FIG. 3, in the bonding interface between the solid electrolyte and the electrodes in the three-layer ceramic laminated body, the electrode material particles 6 enter the solid electrolyte 1 and the electrode material particles 6 The surface was roughened so as to be buried deeper in the solid electrolyte 1 than in the side.

Then, this three-layer ceramic laminated body was fired at 1400 ° C. to obtain a solid oxide fuel cell comprising a co-sintered three-layer membrane.

(Embodiment 2) In this embodiment, the solid electrolyte material particles are cut from the surface of the ceramic molded body for an electrode.
This is a roughened interface between the electrode and the solid electrolyte.

First, a fuel electrode ceramic green sheet was produced in the same manner as in Example 1.

On the other hand, a ceramic green sheet for an air electrode was produced in the same manner as in Example 1.

On one surface of each of the obtained ceramic green sheets for electrodes, solid electrolyte material particles of yttria-stabilized zirconia (YSZ) having an average particle diameter of 10 μm were adhered.

Each of the ceramic green sheets for electrodes to which the solid electrolyte material particles are attached is sandwiched between plastic films having flat surfaces from both sides, and then put into a plastic bag. And press-bonded using a warm isostatic press.

FIG. 4 shows a cross section of the surface portion of the ceramic green sheet for an electrode in which the solid electrolyte material particles are cut into the surface.

As can be seen, the solid electrolyte material particles 4 of yttria-stabilized zirconia (YSZ) adhering to the surface of the electrode 2 enter the electrode 2 so as to bite from the electrode surface, and the surface of the ceramic green sheet molded body for the electrode is removed. Had been roughened.

On the other hand, in the same manner as in Example 1, ceramic green sheets for a solid electrolyte were prepared, and several ceramic green sheets for a solid electrolyte were stacked to form a laminate of ceramic green sheets for a solid electrolyte.

Then, the previously prepared ceramic green sheets for the fuel electrode and the air electrode whose surfaces have been roughened are placed on the surface of the laminate of the ceramic green sheets for a solid electrolyte. The sheets are stacked so that the surfaces of the sheets are aligned with the surfaces of the laminates of the ceramic green sheets for solid electrolyte, and after putting these in a plastic bag, the inside of the bag is evacuated and a warm isostatic press is used. To obtain a three-layer ceramic laminate formed of a fuel electrode, a solid electrolyte membrane, and an air electrode.

As shown in the cross-sectional view of FIG. 5, the joining surface between the solid electrolyte 1 and the electrode 2 in the three-layer ceramic laminated molded body is such that the solid electrolyte material particles 4 enter the electrode 2 and the solid electrolyte material particles 4 Electrode 2 rather than solid electrolyte 1 side
It was roughened so that it was buried deep in the side.

Then, the three-layer film ceramic laminate was fired at 1400 ° C. to obtain a solid oxide fuel cell comprising a co-sintered three-layer film.

(Comparative Example) For the solid electrolyte fuel cells of Examples 1 and 2 manufactured as described above, for comparison, solid electrolyte material particles were coated on the surface of the ceramic green sheet for solid electrolyte. A solid oxide fuel cell was manufactured in which the bonding surface between the electrode and the solid electrolyte was roughened.

That is, a ceramic green sheet for a solid electrolyte was prepared in the same manner as in Example 1, and material particles of a solid electrolyte having an average particle diameter of 10 μm were attached to the front and back surfaces.
Further, in the same manner as in Example 1, ceramic green sheets for the electrodes of the fuel electrode and the air electrode were produced, and were respectively superposed on the front and back surfaces of the ceramic green sheet for a solid electrolyte. Next, this is put in a plastic bag, the inside of the bag is evacuated, and pressed using a warm isostatic press to form a three-layer ceramic laminate comprising a fuel electrode, a solid electrolyte membrane, and an air electrode. A molded article was obtained.

Then, the three-layered ceramic laminated body was fired at 1400 ° C. to obtain a solid oxide fuel cell comprising a co-sintered three-layered film.

The obtained solid oxide fuel cells were connected together with the solid oxide fuel cells obtained in Examples 1 and 2 as shown in FIG. 6, and the power generation characteristics were measured.

In FIG. 6, 7 is a solid oxide fuel cell, 8 is a solid electrolyte layer, 9 is a fuel electrode, and 10 is an air electrode. 11 is a fuel gas supply pipe, 12 is an air supply pipe,
13 is a platinum wire, 14 is a variable resistor, 15 is an oscilloscope, 16 is an ammeter, and 17 is a mercury switch.

Then, the solid oxide fuel cell 7 is
While maintaining the temperature at 0 ° C., the fuel gas and the air are supplied to the fuel electrode 9 and the air electrode 10 through the fuel gas supply pipe 11 and the air supply pipe 12, respectively, to cause an electrode reaction via the solid electrolyte membrane 8. Was. Then, while observing with the ammeter 16, the voltage drop due to the polarization of the fuel electrode 9 and the air electrode 10 in a state where a current of 300 mA / cm ² flows was measured with the oscilloscope 15 by the current interrupt method. The fuel utilization at this time was set to 40%. Table 1 shows the measurement results. The solid oxide fuel cell obtained in Example 2 had the same tendency as Example 1.

[0042]

[Table 1]

Next, the measurement results will be considered. The smaller the value of the voltage drop due to the polarization, the wider the effective area of the electrode and the better the performance as a fuel cell. According to Table 1, it is shown that the product of Example 1 has a smaller voltage drop due to polarization than the product of Comparative Example, and therefore, the product of Example 1 has a larger effective electrode area than the product of Comparative Example, and has a power generation characteristic. It can be seen that was improved.

[0044]

According to the present invention, in a solid oxide fuel cell, it is possible to prevent the electrode material or the solid electrolyte material from being distributed at the interface between the solid electrolyte and the electrode, thereby preventing the generation of pores. Therefore, roughening of the interface between the solid electrolyte and the electrode can be easily and reliably performed, the effective electrode area at the interface between the solid electrolyte and the electrode can be increased, and power generation characteristics are improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an interface between a solid electrolyte and an electrode obtained by attaching conventional solid electrolyte particles to the surface of a solid electrolyte.

FIG. 2 is a cross-sectional view of the solid oxide fuel cell according to the present invention near the solid electrolyte surface.

FIG. 3 is a sectional view of an interface between a solid electrolyte and an electrode of a solid oxide fuel cell according to the present invention.

FIG. 4 is a cross-sectional view near the electrode surface of the solid oxide fuel cell according to the present invention.

FIG. 5 is a sectional view of an interface between a solid electrolyte and an electrode of the solid oxide fuel cell according to the present invention.

FIG. 6 is a connection diagram for measuring power generation characteristics of a solid oxide fuel cell.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 solid electrolyte 2 electrode (air electrode or fuel electrode) 3 contact interface between solid electrolyte and electrode 4 material particles of solid electrolyte 5 pores 6 electrode material particles 7 solid electrolyte fuel cell 8 solid electrolyte layer 9 fuel electrode 10 air electrode

Claims (4)

[Claims] An electrode material is provided on a bonding surface between the solid electrolyte and the electrode, and an electrode material particle is provided on a joint surface between the solid electrolyte and the electrode, and each of the electrode material particles is closer to the solid electrolyte side than to the electrode side. A solid oxide fuel cell characterized by being buried deep. 2. A solid electrolyte provided with electrodes on the front and back surfaces thereof, wherein solid electrolyte material particles are provided on a joint surface between the solid electrolyte and the electrode, and wherein each of the solid electrolyte material particles has an electrode position higher than that of the solid electrolyte. A solid oxide fuel cell characterized by being buried deep in the side. 3. A fuel electrode material particle is adhered to one of the surfaces of the solid electrolyte ceramic molded body and an air electrode material particle is adhered to the other, and the solid electrolyte ceramic molded body is sandwiched from both sides and pressed to form the fuel electrode material. The particles and the cathode material particles are made to bite into the surface of the solid electrolyte ceramic molded body, and further, the fuel electrode ceramic molded body is provided on the one of the solid electrolyte ceramic molded body surfaces, and the air electrode ceramic molded body is provided on the other. A method for producing a solid oxide fuel cell, comprising: arranging and laminating each of them, pressing them to form a laminated molded body, and firing the laminated molded body. 4. A solid electrolyte material particle is adhered to a surface of a fuel electrode ceramic molded body or an air electrode ceramic molded body,
The fuel electrode ceramic compact or air electrode ceramic compact is sandwiched from both sides and pressed to cause the solid electrolyte material particles to bite into the surface of the fuel electrode ceramic compact or the air electrode ceramic compact. The surface of the fuel electrode ceramic molded body or the air electrode ceramic molded body into which the material particles have penetrated is arranged and laminated on the surface of the solid electrolyte ceramic molded body, and pressed to form a laminated molded body. And a method for producing a solid oxide fuel cell.