JP3334147B2 - Method for manufacturing solid oxide fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a method for manufacturing a solid oxide fuel cell.

[0002]

2. Description of the Related Art As shown in JP-A-2-18874, a solid oxide fuel cell, which is a kind of high-temperature fuel cell, is well known.

As shown in FIG. 1 (FIG. 1) of the above publication, the battery 10 is constructed by winding a pneumatic electrode 16, an electrolyte 18, and a fuel electrode 20 around a support tube 22 as a core. The air electrode 16 is provided with an interconnect 26 for guiding it out.

The interconnecting portion 26 is a conductor for connecting cells in series, and is called an interconnector in a cylindrical battery and a separator in a flat battery.

The air electrode 16 and the fuel electrode 20 shown in FIG. 1 (FIG. 1) can be exchanged.
In this case, the interconnect 26 is led out of the fuel electrode 20.

As described above, the interconnect 26 may be connected to both the air electrode and the fuel electrode due to the electrode arrangement.

The air electrode 16 is a La _1-x M1 _{x + Y} M2 _z O ₃ having porosity, high conductivity and oxidation resistance.
(M1 is one of Ca, Mg, and Sr. M2 is Co, M
n. ) Is a representative example.

A typical example of the fuel electrode 20 is a Ni / ZrO ₂ cermet having porosity, high conductivity and reduction resistance.

The interconnect 26 is made of La which has denseness, high conductivity, resistance to oxidation and reduction.
MCrO ₃ (M is Ca, Mg, or Sr) is a typical example.

That is, LaCrO ₃ is extremely difficult to be sintered, and La _1-x M _x CrO ₃ (M is C
a, Mg, or Sr. There is a method of doping (adding) an M element such as 0 <x ≦ 0.5). In particular, La _1-x Ca _x CrO ₃ (0.2 ≦ x) where the M element is Ca
<0.5) can be fired at a temperature of 1200 ° C. or higher.

[0011]

However, the above LaMC
Although rO ₃ alone can produce a sufficiently dense and highly conductive fired body, if this is bonded and fired to an air electrode or a fuel electrode, LaMCrO ₃ becomes remarkably porous and the conductivity is also found to be reduced. .

Accordingly, it is an object of the present invention to provide a technique for maintaining denseness and high electrical conductivity even after a step of bonding and firing an interconnect.

[0013]

In order to achieve the above object, the method of the present invention comprises the steps of:
Attaches a fuel electrode and attaches an interconnect to this electrode
The air electrode or the fuel electrode
In the formula , La _1-x M _{1 x + y} M 2 _z O ₃ , where M 1 is Ca, M
g or Sr, and M2 is either Co or Mn.
X, y and z are appropriately selected and the thickness is small.
A precoat layer of at least 5 μm is provided.
To attach interconnects by firing on the coat layer
did.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 (a) to 1 (c) are flow charts for manufacturing a solid oxide fuel cell according to the present invention. In FIG. 1, a porous support 2 of stabilized zirconia and an air electrode 3 are attached. (A). The air electrode 3 at this time is LaN1M2O
₃ (N1 is one of Ca, Mg, and Sr, preferably S
r. M2 is either Co or Mn, preferably M
n. ).

Next, as shown in FIG. 1B, a precoat layer 4 is formed on the air electrode 3. Specifically, the pre-coat layer 4 is _{La 1-x M1 x + y} M2 z O 3 (M1 is Ca, M
Any of g and Sr is desirably Ca. M2 is the same as M2 of the air electrode 3. x is in the range of 0 <x <0.6, preferably in the range of 0.2 ≦ x ≦ 0.4. y is in the range of 0 ≦ y ≦ 0.4, preferably in the range of 0 ≦ y ≦ 0.1. Z is in the range of 0.7 ≦ z ≦ 1.2, preferably z 、 1.0. ) And a thickness of 5 μm or more, a thriller coating method, a sheet bonding method, a chemical vapor deposition method (CV
D), the precoat layer 4 is formed by physical vapor deposition (PVD) or thermal spraying.

Next, as shown in FIG. 1 (c), an interconnect 5 is bonded and fired at about 1400 ° C. on the precoat layer 4 to manufacture the fuel cell 1. Interconnect 5 is La _1-x M
1 _{x + y} Cr _z O ₃ (M1, x, y and z represent the precoat layer 4
Same value as described in. ).

The operation of the fuel cell 1 obtained by the above manufacturing method will be described below.

FIG. 2 is a graph showing the relationship between the thickness of the precoat layer and the electric conductivity. The air electrode 3 is set to (La _0.75 Sr _0.25 ) _0.9
When MnO ₃ , the precoat layer 4 is La _0.6 Ca _0.4 MnO _3, and the interconnect 5 is La _0.7 Ca _0.3 CrO ₃ ,
When the electric conductivity between the lower surface of the precoat layer 4 and the upper surface of the interconnect 5 was measured at 1000 ° C.,
At a thickness of 20 μm, an electrical conductivity of 55 S / cm was obtained.

The case where the thickness of the precoat layer 4 is 0 (zero) corresponds to the conventional example, and the electric conductivity in this case is about 5 S /
cm, the electric conductivity of the fuel cell 1 with the precoat layer 4 according to the present invention was improved by about 11 times.

FIG. 3 is a graph showing the relationship between the thickness of the precoat layer and the gas permeability. When the precoat layer 4 is not provided, the gas permeability per hour reaches 30 m ³ / m ² · hr · atm.
On the other hand, when the precoat layer 4 having a thickness of 5 μm is provided, the gas permeability is about 1.0 m ³ / m ² · hr · atm, and when the precoat layer 4 is 15 μm thick, the gas permeability is almost 0 m ³ / m ² · hr · atm.

The strong effect of the precoat layer was confirmed in FIG. 2 and FIG. 3, and this factor will be considered below. For example, La
In the sintering of CaCrO ₃ , it is considered that the liquid phase of the compound of Ca and Cr generated near 1200 ° C. contributes to the densification. However, if the interconnect is fired and adhered directly to the air electrode or fuel electrode, the material of the interconnect La
M1 component (Ca, Sr or Mg) in M1CrO ₃ will diffuse into the air electrode or fuel electrode, as a result, unable generation liquid phase sintering defect, that is, inference that becomes porous.

Alternatively, it has been speculated that at around the sintering temperature (1200 ° C.), the generated liquid phase (CaCrO ₄ ) flows out to the air electrode or the fuel electrode, resulting in poor sintering, that is, porous.

Regarding any of the above inferences, the present invention effectively prevents the diffusion of the M1 component or the outflow of the liquid phase such as CaCrO _{4 in the} pre-coat layer 4, so that the interconnect 5 has a high density and a high electric power. Conductivity can be maintained.

FIGS. 4A to 4C show FIGS. 1A to 1C.
FIG. 4B is a view showing another embodiment. In FIG. 4B, a precoat layer 7 is formed in a crescent section, and in FIG.
The interconnecting part 8 is attached on the upper part, and the result is a crescent section.

As shown in FIG. 4C, a crescent or half-moon cross section has the advantage that stress during sintering can be reduced.

1 (a) to 1 (c), the pre-coat layer 4 and the interconnect 5 are simultaneously fired, or the interconnect 5 is bonded and fired to the pre-coat 4 after the pre-coat 4 is fired first. Is also good.

It should be noted that the precoat layer 4 is also effective when the interconnect 5 is attached to the fuel electrode.

[0029]

As described above, according to the present invention, the interconnection is provided on the air electrode or the fuel electrode via the precoat layer, so that the interconnection has a sufficiently high density even after the firing step. Thus, a high-quality solid electrolyte fuel cell can be provided.

[Brief description of the drawings]

FIG. 1 is a manufacturing flowchart of a solid oxide fuel cell according to the present invention.

FIG. 2 is a diagram showing the relationship between the thickness of a precoat layer and electric conductivity.

FIG. 3 is a diagram showing the relationship between the thickness of a precoat layer and gas permeability.

FIG. 4 is a view showing another embodiment of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell, 2 ... Porous support, 3 ... Air electrode, 4 ... Precoat layer, 5 ... Interconnection part.

Continuation of the front page (72) Inventor Masahiro Kuroishi 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Examiner at Totoki Equipment Co., Ltd. Susumu Ogawa (56) References JP-A-4-324251 (JP, A (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/02 H01M 8/12

Claims (4)

(57) [Claims] 1. A fuel cell comprising an air electrode or a fuel electrode attached to a porous support, and an interconnecting portion attached to this electrode.
La _1-x M1 _{x + y} M2 _z O _{3 wherein} M1 is Ca, Mg, S
r, M2 is one of Co and Mn, x, y, and z are appropriately selected, and a precoat layer having a thickness of at least 5 μm is provided. A method for manufacturing a solid oxide fuel cell, comprising an interconnect. 2. The solid oxide fuel cell according to claim 1.
The method for producing Layer is slurry core
Sheet method, sheet bonding method, chemical vapor deposition (CVD), physical vapor deposition
Wearing method (PVD) Or by spraying.
A method for manufacturing a solid oxide fuel cell. 3. The solid oxide fuel cell according to claim 1.
The method of manufacturing The part is La _1-x M1 _{x + y}
Cr _z O _Three Where M1 is one of Ca, Mg, and Sr
And x, y and z are 0.2 ≦ x ≦ 0.4, 0 ≦ y ≦
0.1 and 0.7 ≦ z ≦ 1.2 Specially
A method for manufacturing a solid oxide fuel cell. 4. The solid oxide fuel cell according to claim 1.
The method for producing M1 of the layer is Ca
M2 is Mn, and M1 of the interconnect is Ca
To be Of a solid oxide fuel cell characterized by the following:
Construction method.