JP2957404B2 - Single cell manufacturing method of solid oxide fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a single cell of a solid oxide fuel cell, and more particularly, to a method of manufacturing a single cell of a solid oxide fuel cell capable of reducing the manufacturing cost and increasing the mechanical strength. About the law.

[0002]

2. Description of the Related Art Among fuel cells that have been attracting attention as low-pollution energy sources, solid electrolyte fuel cells, in particular, are expected to have a high reaction rate without electrolyte leakage. A solid oxide fuel cell stacks a number of single cells (hereinafter, also referred to as single cells), which are the minimum unit of the battery,
This is electrically connected in series or parallel,
Current collectors are incorporated on both electrode surfaces of the single cell in order to reduce the internal resistance of the battery.

Meanwhile, a solid electrolyte membrane constituting a unit cell is required to have a high density, while an electrode membrane is required to be porous. It is very difficult to laminate a porous electrode membrane on a dense solid electrolyte membrane. Conventionally, a green solid electrolyte membrane composed of the constituent materials of the solid electrolyte membrane and an electrode membrane composed of the electrode material A co-sintering method of bonding a green body and firing the green body integrally has been widely adopted.

[0004] However, in the above prior art, since the current collector (electrode) material and the electrolyte material have different shrinkage processes during sintering, the ceramic raw material powder is calcined in advance before co-sintering or the constituent materials are It was necessary to strictly control the shrinkage process by controlling the particle size. Therefore, there is a problem that the yield of the material is reduced and the production cost is high. In particular, the yield of the material when a large-area single cell is manufactured is extremely low, and improvement thereof has been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to eliminate the need for a special pretreatment, to increase the material yield rate and to reduce the manufacturing cost. The object of the present invention is to provide a method for manufacturing a unit cell of a fuel cell.

[0006]

In order to achieve the above object, the present invention relates to a method for manufacturing a single cell of a solid oxide fuel cell, wherein a porous electrode and a skeleton of a current collector are laminated. A solid body composed of the same material as a dense solid electrolyte membrane, which is intended to obtain a fired body in which the solid electrolyte membrane and a porous portion containing an electrode material and a current collector material are laminated by one firing. It is.

That is, the invention claimed in the present application is as follows. (1) In a method for manufacturing a single cell of a solid oxide fuel cell in which an electrode film is formed on the surface of a solid electrolyte membrane, a slurry of constituent materials of the solid electrolyte membrane and porous material particles coated with an electrode material and a current collector material And the mixture is formed into a sheet, dried, and fired to form a dense portion as a solid electrolyte membrane and an electrode film having a current collecting function laminated on the dense portion. Forming a porous part, and then
A method for manufacturing a single cell of a solid oxide fuel cell, comprising forming an electrode film paired with the electrode film having a current collecting function on the other surface of the dense portion.

[0008]

The mixture of the material slurry of the solid electrolyte membrane and the porous material particles coated with the electrode material and the current collector material is formed into a sheet shape to form a green body, and then dried to obtain a green body. The porous material particles coated with the current collector material (hereinafter, also referred to as a coated porous material) float due to low specific gravity, and the surface layer portion of the green body mainly becomes a coated porous material layer, and the lower layer portion Becomes a slurry layer consisting only of the slurry of the constituent material of the solid electrolyte membrane.
By firing this green body, the surface layer becomes a porous electrode film containing both an electrode material and a current collector material, with the porous material particles disappearing, and an electrode film having both current collector functions.
The lower layer is a dense solid electrolyte membrane composed of only the constituent materials of the solid electrolyte membrane. By forming an electrode film paired with the electrode film on the other surface of the solid electrolyte film, a single cell is obtained.

In the present invention, the constituent material of the solid electrolyte membrane
Is, for example, ZrO_Two-Y_TwoO _Three(YSZ), Ce
O_Two-CaO, CeO_Two-Y_TwoO_ThreeSystem is used
You. Further, as a constituent material of the air-side electrode, for example,
Tan-based LaCoO_Three, La _0.7Sr_0.3MnO_Three, L
a_0.7Ca_0.3MnO_Three, La_0.6Ba_0.4Co_0.8C
u_0.2O_ThreeFor example, as a constituent material of the fuel-side electrode,
Nickel-based NiO-ZrO_Two-Y_TwoO_ThreeEtc.
As a constituent material of the current collector, for example, (L
a, Sr) MnO_ThreeSystem perovskite, N on fuel side
i-CeO_Two, Ni-YSZ, Fe-YSZ, etc.
Or the like is used. These constituent materials are, for example, 0.1.
It is pulverized to 1 to 10 μm and used as a slurry. Sura
Solvents for re-preparation include, for example, ethanol, toluene
Or a mixture of ethanol and toluene is used.
You. Formability is ensured for the solid electrolyte membrane material slurry
For example, polyvinyl butyral (PVB),
Add a binder such as butyl phthalate (DBP)
Is preferred.

In the present invention, the porous material particles are particles which are gasified at the time of firing, have a lower specific gravity than a constituent material slurry of the solid electrolyte membrane, and float in the slurry. Such porous material particles include, for example, carbon beads,
Melanin cyanurate and other organic compounds are used. The particle size of the porous material particles is, for example, 20 to 200 μm.

In the present invention, examples of a method of coating the porous material particles with the electrode material and the current collector material include slurry coating and CVD (chemical vapor deposition). The mixing ratio of the constituent material slurry of the solid electrolyte membrane and the coating porous material is, for example, 100: 10 to 100: 50, and particularly preferably 100: 25. By adjusting the mixing ratio of the coating porous material, the thickness of the porous portion serving as the electrode film changes. Examples of a method of forming a mixture of the slurry of the constituent material of the solid electrolyte membrane and the coating porous material into a sheet include a tape casting method. The green body formed into a sheet shape is cut and then naturally dried. Instead of forming the mixture of the material slurry of the solid electrolyte membrane and the coating porous material into a sheet, the surface of the green body in which only the material slurry of the solid electrolyte membrane is formed into a sheet, before the green body is dried Then, a similar green body can be obtained by spraying the coated porous material.

In the present invention, the green body after drying is
For example, it is fired in the atmosphere at 1000 to 1400 ° C. for 1 to 10 hours. The formation of the electrode film on the other surface of the dense solid electrolyte film of the obtained fired body is performed by a known method.

[0013]

Next, the present invention will be described in more detail with reference to examples. FIG. 1 is an explanatory diagram showing a manufacturing flow of a method for manufacturing a single cell of a solid oxide fuel cell according to one embodiment of the present invention, and also shows a schematic diagram of a single cell in a manufacturing process.

In the figure, first, (1) the structure of the solid electrolyte membrane
8 mol% yttria stabilized di
0.1 to 5 μm powder of Luconia (hereinafter referred to as YSZ)
100 g of powder, as an organic binder, for example, polyvinyl
13.5 g of rubutyral (PVB)
12 g of butyl phthalate, for example, toluene
150 cc of a 3 to 2 mixture of ethanol and ethanol
To prepare a YSZ slurry. (2) Then,
High electrode activity as electrode material (La_0.8Sr_0.2)
_0.9MnO_ThreeAs a current collector material with high electrical conductivity
(La_0.6Sr _0.4)_0.9MnO_ThreeUsing
Are kneaded in the same manner as for the electrolyte,
Into a porous material, for example, a particle size of 30 to 50 μm.
Coated on the surface of carbon beads (carbon particles)
Carbon beads coated with electrode material and current collector material
Is prepared. FIG. 2 shows that the electrode material and the current collector material are coated.
This is a cross-sectional portion of the carbon bead. In the figure,
Electrode material and collection are applied to the surface of the carbon beads 5 having a circular cross section.
The coating layers 7 and 6 of the electric conductor material are formed. Co
The thickness of the electrode layer is, for example, 50 to 100 μm, and the electrode material
Of adsorbent and current collector material on carbon bead surface
Is the electrode material up to a thickness of about 30 μm from the outside,
The inside is the current collector material.

Next, (3) the YSZ slurry whose viscosity has been adjusted by adjusting the amount of the residual solvent and carbon beads as the coating porous material are mixed at a mixing ratio of 100: 25. Was spread on a resin sheet coated with a release agent, that is, while controlling the thickness, and molded into a sheet to obtain a green body. (5) Next, the obtained green body was cut into a predetermined shape and dried. At this time, the carbon beads as the coating porous material float on the surface layer portion of the green body because the specific gravity is small. Therefore, the surface layer of the green body is mainly a layer of carbon beads as a coating porous material,
The lower layer is a slurry layer composed of only the solid electrolyte constituent material (YSZ slurry). (6) Next, when this green body is fired at 1450 ° C. for 5 hours in the air, the carbon beads disappear and the porous material made of the constituent material of the solid electrolyte membrane contains the electrode material and the current collector material. A fired body is obtained by laminating an air-side electrode film having a body function and a solid electrolyte membrane having a dense structure composed only of the constituent materials of the solid electrolyte membrane. After gradually cooling the obtained fired body to room temperature,
(7) On the other surface of the solid electrolyte membrane on which the air-side electrode is not provided, 30-40 vol% Ni-YSZ (nickel cermet) is prepared on the other surface of the solid electrolyte membrane by a method substantially similar to that of the electrolyte. The material slurry of the electrode is applied to a thickness of 0.2 mm, and then (8) 1400 ° C. in the atmosphere.
For 5 hours to form a fuel-side electrode, thereby completing (9) a single cell. The obtained single cell was laminated with a gas separator to form a fuel cell stack, and the fuel cell stack was housed in a predetermined box to constitute a solid oxide fuel cell. Using this solid oxide fuel cell, heat to 1000 ° C.
A power generation test was performed using hydrogen as fuel gas and air as oxidant gas. The results are shown in FIG.

From FIG. 3, it can be seen that the solid oxide fuel cell constituted by using the single cell obtained according to the present embodiment has a direct proportional relationship between the current density and the voltage, and has a good power generation efficiency. According to the present embodiment, a mixture of the material slurry of the solid electrolyte membrane and the carbon beads coated with the electrode material and the current collector material is formed into a sheet to form a green body, which is dried and then fired. By doing so, in one firing step, the carbon beads floating on the surface layer portion of the green body disappear, comprising an electrode material and a porous portion containing a current collector material, an electrode film having a current collector function and Thus, a laminate in which the solid electrolyte membrane composed of the dense portion is integrated is obtained. Therefore, the number of manufacturing steps is reduced, the yield rate of the material is improved, and the manufacturing cost is significantly reduced. Further, since the green body is basically composed mainly of an electrolyte material, the shrinkage during firing becomes uniform, and the mechanical strength is reduced without performing pre-treatment such as calcination required in the conventional method. A large fired body can be obtained. Therefore, the solid electrolyte membrane can be made thinner than before.

In this embodiment, the green body refers to a material obtained by molding the constituent material of the solid electrolyte membrane into a sheet shape before firing. In the green body, the thickness of the upper layer mainly composed of the coated porous material can be adjusted by adjusting the mixing amount of the coated porous material and the viscosity of the YSZ slurry. In this example, the thickness of the coated porous material layer was, for example, 1.0 mm in a green body state. For the composition of the electrode material and the current collector material, the former is more electrode active,
The latter is a composition having high electric conductivity.

In this embodiment, the air-side electrode is shown as an electrode film which is integrally fired with a skeleton made of the same material as the solid electrolyte membrane, but a fuel-side electrode may be used.

[0019]

According to the present invention, the dense part to be the solid electrolyte membrane and the porous part containing the electrode and the current collector material laminated on the dense part are formed of the same material, By integrally firing, the shrinking step becomes uniform, so that a strong unit cell structure without distortion or the like can be obtained. Further, since the yield rate of the material is improved, the manufacturing cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a manufacturing flowchart showing one embodiment of the present invention.

FIG. 2 is a sectional view of a coated porous material according to one embodiment of the present invention.

FIG. 3 is a diagram showing a power generation effect of a fuel cell according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... YSZ green, 2 ... Coat porous material, 3 ... Dense part (solid electrolyte membrane), 4 ... Porous part (electrode film), 5 ... Carbon beads, 6 ... Current collector material layer, 7 ... Electrode material layer.

Claims (1)

(57) [Claims] 1. A method for producing a solid electrolyte fuel cell unit cell comprising forming an electrode film on the surface of a solid electrolyte membrane, comprising a slurry of constituent materials of the solid electrolyte membrane and a porous material coated with an electrode material and a current collector material. Material particles, the mixture is formed into a sheet, dried, and fired to form a dense portion as a solid electrolyte membrane, and an electrode film having a current collecting function laminated on the dense portion. To form a porous portion,
Next, an electrode film paired with the electrode film having a current collecting function is formed on the other surface of the dense portion, and a method for manufacturing a unit cell of a solid oxide fuel cell is provided.