JP2003331874A - Interconnector for solid oxide fuel cell and its formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an interconnector for a solid oxide fuel cell (SOFC) having an excellent performance and to provide its formation method. <P>SOLUTION: The solid oxide fuel cell comprises: unit cells each composed of an electrolyte 2 and a fuel electrode 3 on a base tube of a cylindrical air electrode 1 or a hollow flat plate (TFP type); and this interconnector 4 for electrically connecting the unit cells to each other. Powder having a particle diameter of 30-60 μm of the perovskite oxide of titanium-doped lanthanum calcium chromate La<SB>1-x</SB>Ca<SB>x</SB>Cr<SB>1-y</SB>Ti<SB>y</SB>O<SB>3</SB>(0<x≤0.4, 0<y≤0.3) is used as the material of the interconnector 4. The dense and thin-shaped interconnector having thermal expansion almost coincident with those of other constituent materials and a film thickness of around 150-200 μm is made by spraying the powder with the power of 60-90 kW to enhance its reliability. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid oxide fuel cell interconnector having excellent performance and a method for forming the same.

[0002]

2. Description of the Related Art A fuel electrode and an oxidizer electrode are arranged via a ceramic electrolyte, and finally hydrogen is used as fuel.
In the solid oxide fuel cell that supplies oxygen or air as an oxidizer to generate electricity by using the reverse reaction of electrolysis of water, in order to obtain a practically sufficient power generation amount of the fuel cell,
Unit element of the above solid oxide fuel cell (single cell)
It is necessary to electrically connect a plurality of these in series and in parallel (stacking). During the operation of the fuel cell, the negative electrode side (fuel electrode side) of the cell is exposed to a reducing atmosphere, and the positive electrode side (oxidizer electrode side) is exposed to an oxidizing atmosphere. It is necessary to secure the ionic conductivity of the fuel cell body and keep the fuel cell body at a high temperature of 600 ° C. or higher at which redox easily occurs. Therefore, in the inter-cell connection in a solid oxide fuel cell, one of the positive electrode and the negative electrode is covered with a gas-impermeable and electrically conductive ceramic material (interconnector), and then with this interconnector and the interconnector. The electrodes must be electrically connected in a high temperature oxidizing atmosphere or a high temperature reducing atmosphere. Therefore, the interconnector is firmly adhered to one of the positive electrode and the negative electrode of the fuel cell to maintain the electrical conductivity, and is dense enough not to permeate gas or fuel or air. Need to be For this purpose, LaCrO ₃ type perovskite type oxides have been conventionally used as interconnectors.

[0003]

However, the above-mentioned LaCrO ₃ type perovskite type oxide is difficult to sinter, and a temperature of 1600 ° C. or higher is required for dense sintering. Firing at the same time as other constituent materials is not suitable for practical use because other cell constituent materials cannot be thermally endured. Therefore, a method of manufacturing a film-shaped interconnector by thermal spraying has been adopted, but it is difficult to manufacture it densely, and it is difficult to manufacture a stable interconnector such as cracks caused by thermal expansion.

The object of the present invention is to solve the above problems, and is a denser, thermally and mechanically stable and high performance interconnector for a solid oxide fuel cell, and an interconnector thereof. It is to provide a forming method.

[0005]

In order to achieve the above object, the present invention has a structure as described in the claims. That is, as described in claim 1, an interconnector used in a solid oxide fuel cell, wherein the interconnector has a composition of La _1-x Ca _x C.
r _1-y Ti _y O ₃ (0 <x ≦ 0.4, 0 <y ≦ 0.3)
An interconnector for a solid oxide fuel cell, which is composed of titanium doplantan calcium chromite represented by

Further, as described in claim 2, claim 1
In the above, the above titanium dolan tan calcium chromite has a composition of La _0.7 Ca _0.3 Cr _0.9 Ti.
_0. An interconnector for a solid oxide fuel cell, which is ₁ O ₃ .

According to a third aspect of the present invention, there is provided a method of forming an interconnector used in a solid oxide fuel cell, wherein the composition is La _1-x Ca _x Cr _1-y Ti _y O.
₃ (0 <x ≦ 0.4, 0 <y ≦ 0.3), and a method for forming an interconnector for a solid oxide fuel cell, which comprises spraying a powder of titanium doplantan calcium chromite on a desired location. To do.

According to a fourth aspect of the present invention, there is provided a method of forming an interconnector used in a solid oxide fuel cell, wherein the composition is La _1-x Ca _x CrO ₃ (0 <x≤.
Lanthanum calcium chromite represented by 0.4),
This is a method for forming an interconnector for a solid oxide fuel cell, in which a powder obtained by mixing titania TiO ₂ in a predetermined ratio is sprayed onto a desired portion.

[0009] Further, as described in claim 5, claim 4
In the above method, a method of forming an interconnector for a solid oxide fuel cell, which comprises spraying a powder obtained by mixing the lanthanum calcium chromite with titania at a ratio of 30 mol% or less at a desired location.

Further, as described in claim 6, claim 3
The method for forming an interconnector for a solid oxide fuel cell according to claim 5, wherein the powder has a particle diameter of 30 to 60 μm.

Further, as described in claim 7, claim 3
The method for forming a solid oxide fuel cell interconnector according to claim 5, wherein the thermal spray output of the powder is 60 to 90 kW.

[0012] Further, as described in claim 8, claim 3
The film thickness of the interconnector formed by spraying the powder according to any one of claims 1 to 7 is 150 to 2
A method for forming a solid oxide fuel cell interconnector having a diameter of 00 μm.

Material for Interconnector Used in the Present Invention Titanium Dolan Plant Calcium Chromite La
_1-x Ca _x Cr _1-y Ti _y O ₃ (0 <x ≦ 0.4,
When 0 <y ≦ 0.3), the sinterability is improved by titanium doping, and a film with less gas permeation can be formed after thermal spraying.

Further, as shown in the thermal expansion characteristics [indicates sample temperature (° C.) and expansion per 1 mm (μm)] in a reducing atmosphere (mixed gas atmosphere of N ₂ and H ₂ ) in FIG. The doped calcium lanthanum chromite has suppressed thermal expansion and reduction expansion compared to those not doped or doped with aluminum, and is a typical material used as an electrolyte and an air electrode.
SZ (yttria stabilized zirconia) and LSM
(Lanthan strontium manganite) is almost the same value. This makes it possible to make the sprayed film more dense by heat treatment after film formation, and also improves the stability in long-term use as a fuel cell.

Further, as shown in FIG. 2, titanium doping also has an effect of suppressing a decrease in electric conductivity in a reducing atmosphere (mixed gas atmosphere of N ₂ and H ₂ ). In FIG. 2, the horizontal axis represents 1000 / T (1 / K), T: absolute temperature, K: Kelvin, and the vertical axis represents electrical conductivity (S / c).
m) and S: Siemens. Since the interconnector is used in both oxidizing and reducing atmospheres, a decrease in electrical conductivity in a reducing atmosphere leads to a decrease in fuel cell performance. In this sense, a solid oxide fuel cell having a sprayed film interconnector using titanium doplantan calcium chromite has the effect of achieving higher performance.

The above-mentioned effects are obtained by directly spraying titanium doplantane calcium chromite with lanthanum calcium chromite La _1-x Ca _x CrO ₃ (0 <
The same applies to spraying a powder obtained by mixing titania TiO ₂ at a ratio of 30 mol% or less to x ≦ 0.4), and a solid oxide fuel cell having a good interconnector can be obtained.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION <Embodiment 1> Hereinafter, an example of an embodiment of the present invention will be described in more detail with reference to the drawings. FIG. 3 is a cross-sectional view of a solid oxide fuel cell unit that exemplifies an SOFC cell having a hollow flat plate structure.
_{On the} air electrode 1 composed of a porous substrate of _1-x Sr _x MnO ₃ , the YSZ electrolyte 2 is arranged in a portion excluding a space for spraying the interconnector 4, and Ni / YSZ is formed on a portion of the electrolyte 2. The fuel electrode 3 is arranged to form a unit cell of a solid oxide fuel cell. In the portion where the electrolyte was not arranged for this interconnector, titanium doplantane calcium chromite La _0.7 Ca _{0 . 3} Cr
Output of 60 to 90 using _0.9 Ti _0.1 O ₃ powder
A dense interconnector is produced by performing thermal spraying at kW. The film thickness can be as thin as 150 to 200 μm, and the electrical loss of the fuel cell can be reduced. In addition, the La _0. The spray output of powder _{7 Ca 0.3 Cr 0.9 Ti 0.1 O} 3, most dense and good sprayed film about 85kW was obtained.

Titanium Doplantan Calciu for Thermal Spraying
Mukuromite La_1-xCa_xCr _1-yTi_yO
_Three(0 <x≤0.4, 0 <y≤0.3)
La_TwoO _ThreeAnd CaCO_ThreeIs (1-x) / 2: x, Cr
(NO_Three)_ThreeAnd TiO_TwoIn a molar ratio of 1-y: y
After thoroughly mixing and pulverizing with a ball mill, 6 in air at 900 ° C
After calcination for an hour, remix and pulverize to 1200-140
A single perovskite phase is obtained by firing at 0 ° C.
It was Average particle size of powder changes with firing temperature and time
However, in order to produce a good thermal spray coating,
More preferably, it is about 50 μm.

<Embodiment 2> Instead of producing the titanium spray lanthanum calcium chromite for thermal spraying of Embodiment 1, La ₂ O ₃ , CaCO ₃ , Cr (NO ₃ ) is used.
Lanthanum calcium chromite was prepared from ₃ and commercially available titania TiO ₂ was used in an amount of about 10 mol% with a ball mill.
The same effect as in the above-described first embodiment can be obtained by using the material mixed for time for thermal spraying.

As described in detail in the above embodiment, the thin and dense solid oxide fuel cell is close to other solid oxide fuel cell constituent members, and the electric conductivity in the reducing atmosphere is lowered. A small interconnector can be realized and the performance of the solid oxide fuel cell can be improved.

[0021]

According to the present invention, as an interconnector for a solid oxide fuel cell, it has good sinterability and a thermal expansion coefficient close to that of other constituent members such as LSM and YSZ, and the reduction expansion was suppressed. A thin and dense interconnector can be produced by a thermal spraying method using a material on a cylindrical or hollow flat plate type cathode electrode tube, and the solid oxide fuel cell unit has excellent performance as compared with the prior art. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing the thermal expansion characteristics of titanium doplantan calcium chromite exemplified in the embodiment of the present invention in comparison with aluminum doplantan calcium chromite and lanthanum calcium chromite.

FIG. 2 is a diagram showing the electrical conductivity of titanium doplantan calcium chromite exemplified in the embodiment of the present invention in a reducing atmosphere in comparison with aluminum doplantan calcium chromite.

FIG. 3 is a schematic diagram showing a cross-sectional structure of the TFP type solid oxide fuel cell illustrated in the embodiment of the present invention.

[Explanation of symbols]

1 ... Air electrode 2 ... Electrolyte 3 ... Fuel pole 4 ... Interconnector

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4K031 AA06 AB07 AB08 CB02 CB09                       CB42 DA02 FA01                 5H026 AA06 BB04 BB08 CC06 CV02                       EE13 HH01 HH03 HH05 HH06

Claims (8)

[Claims] 1. An interconnector used in a solid oxide fuel cell, wherein the interconnector has a composition of L.
a _1-x Ca _x Cr _1-y Ti _y O ₃ (0 <x ≦ 0.
An interconnector for a solid oxide fuel cell, characterized in that it is composed of titanium dolan tan calcium chromite represented by 4, 0 <y ≦ 0.3). 2. The composition according to claim 1, wherein the titanium doplantan calcium chromite has a composition of La _0.7 Ca.
An interconnector for a solid oxide fuel cell, which is _0.3 Cr _0.9 Ti _0.1 O ₃ . 3. A method of forming an interconnector used in a solid oxide fuel cell, the composition being La _1-x Ca.
_x Cr _1-y Ti _y O ₃ (0 <x ≦ 0.4, 0 <y ≦ 0.
A method for forming an interconnector for a solid oxide fuel cell, which comprises spraying a powder of titanium doplantan calcium chromite represented by 3) onto a desired portion. 4. A method of forming an interconnector used in a solid oxide fuel cell, the composition of which is La _1-x Ca.
lanthanum calcium chromite represented by _{x CrO 3 (0 <x ≦} 0.4), solid oxide fuel cells for a powder mixed titania TiO ₂ at a predetermined ratio, characterized in that spraying on a desired position For forming interconnectors for automobiles. 5. The method for forming an interconnector for a solid oxide fuel cell according to claim 4, wherein a powder obtained by mixing the lanthanum calcium chromite with titania at a ratio of 30 mol% or less is sprayed onto a desired portion. . 6. The method for forming an interconnector for a solid oxide fuel cell according to claim 3, wherein the particle size of the powder is 30 to 60 μm. 7. The method for forming an interconnector for a solid oxide fuel cell according to claim 3, wherein the thermal spray output of the powder is 60 to 90 kW. 8. The solid oxide fuel cell according to claim 3, wherein the interconnector formed by spraying the powder has a film thickness of 150 to 200 μm. For forming interconnectors for automobiles.