JP2003197204A - Electrochemical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise the operating efficiency more in the electrochemical cell of a honey-comb shape. <P>SOLUTION: Electrochemical equipment 20 has a honey-comb-like supporting component 12. The solid electrolyte materials 2A and 2B of the quality of airtight constitute at least one part of the supporting component 11. The electrochemical equipment is equipped with two or more first gas flow ways 7, two or more second gas flow ways 8, the 1st electrodes 9, which face to the gas flow ways 7, and the 2nd electrodes 10, which face to the gas flow ways 8. Two or more single cells 21A and 21B are constituted by the electrodes 9 and 10, and the solid electrolyte materials 2A and 2B. The two or more single cells are connected in-series each other. The thickness a1 of the functional part 9a, which constitutes a single cell in the 1st electrodes 9, is smaller than the thickness b1 of the connection part 9b, which contributes to the in-series connection of the single cell in the 1st electrode. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrochemical cell such as a solid oxide fuel cell, a steam electrolysis cell, an oxygen pump and a Knox decomposition cell.

[0002]

2. Description of the Related Art Solid oxide fuel cells (SOFC) are
It is roughly divided into so-called flat plate type and cylindrical type. It is the cylindrical SOFC that is said to be most practically used now,
From the viewpoint of output density per unit volume, flat plate type S
OFC is more advantageous. However, in a flat plate type SOFC, a so-called separator and a power generation layer are alternately laminated to form a power generation stack, but the SOFC of this method has a problem in a sealing method and the like.

The applicant of the present invention has disclosed a honeycomb-shaped solid oxide fuel cell in Japanese Unexamined Patent Publication No. 10-40934. The support of this battery consists of a solid electrolyte and an interconnector. This support is provided with a large number of through holes, and each through hole is surrounded by an interconnector and a solid electrolyte layer. And
An air electrode and a fuel electrode are formed on the inner wall surface of each through hole. Such a structure has a high power density per unit volume, and it is relatively easy to form an airtight seal.

[0004]

When the present inventor examined such a honeycomb-shaped SOFC, there is room for further improving the power generation efficiency for the fuel per unit capacity flowed in the gas passage. found.

An object of the present invention is to further improve the operating efficiency of a honeycomb-shaped electrochemical cell.

[0006]

According to the present invention, a honeycomb-shaped support member, a plurality of first gas flow paths, and a plurality of second gas flows, at least a part of which is made of an airtight solid electrolyte material, are provided. Channel, a first electrode facing the first gas flow channel, and a second electrode facing the second gas flow channel, and a plurality of electrodes depending on the first electrode, the second electrode, and the solid electrolyte material. Of the unit cell of the first electrode having a thickness a1 of a functional portion constituting the unit cell.
Is smaller than the thickness b1 of the connection portion of the first electrode that contributes to the series connection of the single cells.

Further, according to the present invention, a honeycomb-shaped support member, a plurality of first gas passages, a plurality of second gas passages, at least a part of which are made of a solid electrolyte material of airtightness, The first electrode facing the gas flow path of, and a second electrode facing the second gas flow path, a plurality of single cells by the first electrode, the second electrode and the solid electrolyte material. In the constituted electrochemical device, the thickness a2 of the functional portion of the second electrode forming the unit cell is the thickness b2 of the connecting portion of the second electrode that contributes to the series connection of the unit cells. It is characterized by being smaller than.

The present inventor first examined the thickness of each part of the electrode facing the gas flow path of the honeycomb-shaped support,
The electrode is divided into a functional portion that constitutes a single cell and contributes to an electrochemical reaction, and a connecting portion that contributes to the series connection of the single cells, and the thicknesses a1 and a2 of the functional portion are the thickness b of the connecting portion.
By making it smaller than 1 and b2, it has succeeded in further improving the operation efficiency of the cell corresponding to the gas per unit volume flowed in the gas flow path. This is because the efficiency of the electrochemical reaction in the single cell can be improved by reducing (thinning) the thickness a1 and a2 of the functional portion of the electrode facing the gas flow path, and
Thickness b of the connecting portion that contributes to the series connection of a plurality of single cells
This is because by making 1 and b2 large (thick), the internal resistance due to series connection can be reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be further described below with reference to the drawings. FIG. 1 is a cross-sectional view of a support 1 for an electrochemical cell according to an embodiment of the present invention, taken along the cross-sectional direction of the support. The cross-sectional direction means a direction substantially perpendicular to the gas flow path. The support 1 has a honeycomb shape. However, in FIG. 1, only the gas passages of 4 rows × 4 columns are shown due to space limitations, but the number of rows and the number of columns of the gas passages can be appropriately selected.

The support 1 includes solid electrolyte layers 2A and 2B made of a solid electrolyte material and interconnector layers 3A and 3B.
It consists of B and 3C. Solid electrolyte layers 2A, 2B,
The interconnector layers 3A, 3B, and 3C are alternately provided and laminated. 6 is the interface of each layer. Figure 1
In the space 4, 5, from the top to the bottom in
4, 5 are provided in order. Each solid electrolyte layer 2A, 2
B is a main frame 2a facing the spaces 4 and 5, respectively.
And a sub-frame 2b extending from the main frame 2a. Each interconnector layer 3A, 3B, 3C includes a main frame 3a facing the spaces 4 and 5, and a sub-frame 3b extending from the main frame 3a. The sub-frames 2b and 3b are joined at the interface 6.

FIG. 2 is a cross-sectional view schematically showing an electrochemical device 20 including the support 1, the first electrode 9 and the second electrode 10 of FIG. 1, and FIG. FIG.

From the uppermost side to the lowermost side of the electrochemical device 20, a first gas passage 7, a second gas passage 8, a first gas passage 7 and a second gas passage 8 are provided. Are formed in order. Each gas flow path 7, 8 is surrounded by a solid electrolyte layer and an interconnector layer, respectively. A first electrode 9 is provided on the inner wall surface of the support 2 so as to face the first gas flow path 7. A second electrode 10 is provided on the inner wall surface of the support 2 so as to face the second gas flow path 8.

The first electrode 9 and the second electrode 10 are provided so as to sandwich the main frame 2a of the solid electrolyte layers 2A and 2B, thereby constituting the unit cells 21A and 21B. That is, a part of the main frame 2a made of a solid electrolyte material is a part of the ionic conduction part 2 mainly contributing to the electrochemical reaction.
c. Then, a part of the first electrode 9 becomes the functional portion 9a that directly contributes to the electrochemical reaction. Also,
A part of the second electrode 10 becomes the functional portion 10a that directly contributes to the electrochemical reaction. In the example of FIG.
Four unit cells 21A are arranged along the solid electrolyte layer 2A, and four unit cells 21B are arranged along the solid electrolyte layer 2B.

The four unit cells 21A provided along the same solid electrolyte layer 2A are connected in parallel with each other, and the four unit cells 21B provided along the solid electrolyte layer 2B are connected in parallel with each other. Has been done. Single cell 21A and 2
1B means a sub-frame 2b of the solid electrolyte layer 2A, a sub-frame 3b of the interconnector layer 3B, a first electrode 9 and a second electrode 1.
They are connected in series via 0. 10b and 9b function as connecting portions that contribute to the series connection of the single cells.
9c and 10c are interconnector layers 3A and 3c.
It is a portion formed on the main frame 3a of B and 3C. A is the direction of series connection of the single cells, and the electric power is extracted between the terminal interconnector layers 3A and 3C.

Here, as shown in FIG. 3, according to the present invention, the thickness a1 of the functional portion 9a constituting the unit cells 21A and 21B of the first electrode 9 is set to the unit cell of the first electrode 9. The thickness is made smaller than the thickness b1 of the connection portion 9b that contributes to the series connection of. In addition, the unit cell 21 of the second electrode 10
The thickness a2 of the functional portion 10a constituting A and 21B is made smaller than the thickness b2 of the connecting portion 10b of the second electrode 10 that contributes to the series connection of the single cells.

The connecting portions 9b and 10b of the electrodes, which contribute to the series connection of the single cells, may be between the electrode functional portion of a certain single cell and the electrode functional portion of another single cell. In this case, The connection portions 9b and 10b contribute to the series connection of one unit cell and another unit cell. For example, in the example of FIG. 2, the connecting portions 10b and 9b are provided between the electrode functional portion 10a forming the single cell 21A and the electrode functional portion 9a forming the single cell 21B, and the connecting portions 10b and 9b are connected to each other. Contributes to series connection. The connecting portions 9b, 10b of the electrodes that contribute to the series connection of the single cells may be between the electrode functional portion of the terminal single cell and the terminal interconnector layer. In this case, the connecting portions 9b, 10b.
Contributes to the series connection between the terminal single cell and the interconnector layer. For example, in the example of FIG. 2, the electrode functional portion 10a and the interconnector layer 3C that form the unit cell 21B.
There is a connecting portion 10b between and, which contributes to the series connection of the unit cell 21B and the interconnector layer 3C.

In this example, the electrodes 9 and 10 are functional portions 9a and 10a which constitute a single cell and contribute to an electrochemical reaction.
The thicknesses a1 and a2 of the functional portion are divided into the connection portions 9b and 10b that contribute to the series connection of the single cells, and the thickness b of the connection portion is
It is smaller than 1 and b2. Of the electrodes facing the gas flow paths 7 and 8, the thicknesses a1 and a2 of the functional portions 9a and 10a, respectively.
By reducing (thinning) the functional parts 9a, 1
The diffusion resistance of the gas at 0a can be reduced, and the efficiency of the electrochemical reaction in the single cell can be improved. At the same time, the connection portion 9 that contributes to the series connection of the single cells
By increasing the thicknesses b1 and b2 of b and 10b, the internal resistance due to the connection can be reduced.

From the viewpoint of the function and effect of the present invention, the thickness a1 of the functional portion 9a of the first electrode and the thickness b1 of the connecting portion are provided.
The ratio a1 / b1 is preferably 0.8 or less, and more preferably 0.6 or less. Further, from the viewpoint of ensuring the reactivity in the functional portion in design, it is preferable that a1 / b1 is 0.2 or more.

From the viewpoint of the function and effect of the present invention, the thickness a2 of the functional portion 9b of the second electrode and the thickness b2 of the connecting portion thereof.
The ratio a2 / b2 is preferably 0.8 or less, and more preferably 0.6 or less. From the viewpoint of ensuring the reactivity in the functional part in design, a2 / b2 is preferably 0.2 or more.

From the viewpoint of reducing the diffusion resistance of gas in the functional portion of each electrode, a1 and a2 are 80
It is preferably not more than μm, more preferably not more than 60 μm. From the viewpoint of promoting the electrochemical reaction in the functional part, a1 and a2 are 10 μm.
The thickness is preferably not less than 30 μm, more preferably not less than 30 μm.

From the viewpoint of reducing the internal resistance at the connecting portion of each electrode, b1 and b2 are preferably 50 μm or more, and more preferably 70 μm or more. However, if the connecting part of each electrode becomes too thick, gas will not flow to the connecting part, and the gas flow path will become narrower, and the amount of gas diffusion to the functional part will decrease, rather the power generation efficiency per unit volume will be reduced. Is reduced. Therefore,
From the viewpoint of improving output, b1 and b2 are preferably 200 μm or less, and more preferably 150 μm or less.

In a preferred embodiment, the support comprises an interconnector layer made of a gastight electronically conductive material. In a more preferred embodiment, the first gas passage and the second gas passage are surrounded by a solid electrolyte material and an interconnector layer, respectively, as shown in FIGS.

The target of the electrochemical cell of the present invention is SOFC.
Not limited. The electrochemical cell of the present invention comprises an oxygen pump,
It can be used as a high temperature steam electrolysis cell. High temperature steam electrolysis
The cell can be used for hydrogen production equipment and also for removing steam
Can be used for equipment. In this case, the next reaction at each electrode
Give rise to. Cathode: H_TwoO + 2e⁻→ H_Two+ O^2- Anode: O^2-      → 2e⁻+ 1 / 2O_Two

The electrochemical cell of the present invention is provided with NOx, SOx
It can be used as a decomposition cell. This decomposition cell can be used as a device for purifying exhaust gas from automobiles and power generators.

The shape of each gas flow path in the support is not particularly limited, but from the viewpoint of space utilization efficiency, the shape of the cross section of each gas flow path can fill a flat surface without any gaps. Are preferred, and isosceles triangles, regular triangles, rectangles, squares, regular hexagons, etc. are preferred.

As the material of the solid electrolyte layer, yttria-stabilized zirconia or yttria partially-stabilized zirconia is preferable, but other materials can also be used. In the case of a NOx decomposition cell, cerium oxide is also preferable.

The first electrode is, for example, an anode, and the second electrode is, for example, a cathode. Material of interconnector layer,
The material of the anode is preferably a perovskite-type composite oxide containing lanthanum, lanthanum chromite,
More preferably, it is lanthanum manganite or lanthanum cobaltite. The lanthanum chromite, lanthanum manganite, and lanthanum cobaltite may be doped with strontium, calcium, chromium, cobalt, iron, nickel, aluminum or the like. Further, it may be palladium, platinum, ruthenium, platinum-zirconia cermet, palladium-zirconia cermet, ruthenium-zirconia cermet, platinum-cerium oxide cermet, palladium-cerium oxide cermet, or ruthenium-cerium oxide cermet.

The material of the cathode is nickel, palladium, platinum, nickel-zirconia cermet, platinum-zirconia cermet, palladium-zirconia cermet, nickel-cerium oxide cermet, platinum-cerium oxide cermet, palladium-cerium oxide cermet, ruthenium, Ruthenium-zirconia cermet and the like are preferable.

In the case of a fuel cell, the first gas preferably contains gas molecules capable of supplying oxygen ions, and in the case of an electrolysis cell, it preferably contains air or an inert gas, such as oxygen or argon. , And preferably contains nitrogen. In particular, the atmosphere is preferable from the viewpoint of cost.

The second gas preferably contains an oxidizable gas molecule in the case of a fuel cell and a reductively decomposable gas in the case of an electrolysis cell, such as hydrogen gas, water vapor, methane, It preferably contains carbon monoxide, NOx and SOx.

[0031]

[Examples] More specific experimental results will be described below. The electrochemical device 20 shown in FIG. 2 was manufactured. Specifically, first, the following kneaded clay was manufactured. (Kneaded clay for solid electrolyte layer) 8 mol% with an average particle size of 1 μm
4 parts by weight of methyl cellulose and polyvinyl alcohol were mixed with 100 parts by weight of the yttria-stabilized zirconia powder, and 18 parts by weight of water was added to this mixture to obtain a kneaded product using a kneader. This kneaded material was housed in a vacuum clay kneader to produce a cylindrical kneaded material having a diameter of 50 mm and a length of 300 mm.

(Kneaded clay for interconnector layer) 3 parts by weight of methyl cellulose and polyvinyl alcohol were mixed with 100 parts by weight of lanthanum manganite powder having an average particle diameter of 3 μm, and 14 parts by weight of water was added to the mixture. In addition, a kneader was used to obtain a kneaded product. This kneaded material,
Stored in a vacuum clay kneader, diameter 50 mm, length 300 mm
The columnar kneaded clay was manufactured. For each of the above kneaded clay,
By adjusting the amount of polyvinyl alcohol added, the difference in hardness between the kneaded clays was ± 1.

(Molding clay) A kneaded material for a solid electrolyte layer and a kneaded material for an interconnector layer are filled in a cylinder of a biaxial plunger for coextrusion molding, and as shown in FIG. A shaped body having a morphology was produced. At this time, the hydraulic pressure of the plunger was controlled so that the extrusion speed of each kneaded material was almost the same, and thereby the bending of the molded body of the support was prevented.

(Production of Honeycomb Support 1) This molded body was placed in a constant temperature and constant humidity dryer and dried at 80 ° C. After drying, the dried compact was placed in an electric furnace, and the temperature was raised to 1600 ° C at a rate of 40 ° C / hour, and the temperature was raised to 1600 ° C.
Was held for 3 hours and integrally sintered to obtain a support. The dimensions of the obtained support 1 are 2.5 mm in length, 2.5 mm in width, and 50 mm in length. The number of gas flow paths is 10 rows x
There are 100 in 10 rows. From this support, 4 rows × 7 columns were taken out by processing to obtain a support for an evaluation cell. Therefore, the number of the first gas passages is 14, and the number of the second gas passages is also 14.

(Formation of air electrode) An anode (air electrode) was formed as the first electrode 9. Specifically, La with a particle size of 1 μm
2 wt% of ethyl cellulose was added to _0.7 Sr _0.3 MnO ₃ powder, and “CS-12” manufactured by Chisso Corporation was added as a solvent to obtain a slurry. The viscosity was measured with a Brookfield viscometer to find that it was 49P.
It was a sec. This slurry was poured into the spaces 4 shown in FIG. 4 (a), and adhered to the inner wall surface of each space 4. At this time, a masking material made of resin was used to prevent the spaces 4 from adhering to locations other than the inner wall surfaces. This is because the slurry causes a short circuit. Then, FIG.
As shown in (b), one side wall was faced down and left for 1 hour, the masking material was removed, and the solvent was evaporated in a dryer at 120 ° C. This slurry was calcined at 800 ° C. to form the first layer 11. Here, in the first layer 11, the lower side portion 11c becomes thick due to the action of gravity, and the upper side portion 11b and the side portion 11a become thin.

Next, the resin masking material was fixed to the support 1 again, and then the slurry was poured into each space 4 and adhered onto the first layer 11 in each space 4. Then
As shown in FIG. 5A, the state of FIG. 4B was turned upside down and left still for 1 hour. Then, the masking material was removed, and the solvent was evaporated in a dryer at 120 ° C. At this point, as shown in FIG. 5A, the second layer 12 made of the dried slurry is formed on the inner surface of the first layer 11. Here, due to the action of gravity, the second layer 12c becomes thick and the upper portion 12b and the side portion 12a become thin. In this state, the first layer 11 and the second layer 12 were baked by firing at 1200 ° C. to form the first electrode (air electrode) 9 as shown in FIG. 5B.

(Formation of fuel electrode) 8 mol% of particle size 1 μm
Yttria-stabilized zirconia and nickel oxide powder having an average particle size of 1 μm are mixed at a weight ratio of 50/50,
The air electrode was formed on the inner wall surface of the space 5 in the same manner as in the formation example of the air electrode.

In the above-described manufacturing example, by changing the viscosity of the slurry and the slurry injection amount, each dimension a of the electrode
1, a2, b1 and b2 were controlled as shown in Table 1.

(Power Generation Test) Each battery was held by a ceramic manifold, and a platinum mesh was used as a current collector. Pyrex glass was used for the gas seal between the manifold and the battery. This Pyrex glass melts under a power generation condition of 1000 ° C. and exhibits a gas sealing function. As the fuel gas, hydrogen moistened through a room temperature bubbler was used, and as the oxidizing gas, the atmosphere was used. The total flow rate of fuel gas is 200c
c / min. Therefore, each gas channel has 14
A flow rate of cc / min is supplied. The flow rate of the oxidizing gas was 490 cc / min in total. Therefore, in the gas flow path,
An oxidizing gas of 35 cc / min is supplied per piece. 10
At 00 ° C, constant voltage 1.0V (0.5V per single cell,
The power generation output in the case of (two in series) was measured. Table 1 shows the power generation output
Shown in.

[0040]

[Table 1]

As can be seen from these results, it is clear that the present invention significantly improves the power generation output.

[0042]

As described above, according to the present invention, in the honeycomb-shaped electrochemical cell, the operating efficiency of the cell can be further improved.

[Brief description of drawings]

1 is a cross-sectional view schematically showing a support 1.

FIG. 2 is a cross-sectional view schematically showing the electrochemical device 20.

FIG. 3 is a partially enlarged view of FIG.

4A and 4B are diagrams showing a process of forming each electrode.

5A and 5B are diagrams showing a process of forming each electrode.

[Explanation of symbols]

1 Support 2A, 2B Solid electrolyte layer
2a Main frame 2b Sub-frame 2c Ion permeable portion 3A, 3B, 3C Interconnector layer 4, 5 Space 6 Bonding interface between solid electrolyte material and interconnector layer 7 First gas flow passage 8 Second gas flow passage 9th One electrode 9a Functional part 9b Connection part
10 Second electrode 10a Functional part
10b connection part 20 electrochemical device
21A, 21B Single cell a1 Thickness of functional portion of first electrode a2 Thickness of functional portion of second electrode b1 Thickness of connecting portion of first electrode b2 Thickness of connecting portion of second electrode A Direction of series connection

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Kawasaki             2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi             Inside Hon insulator Co., Ltd. F-term (reference) 5H018 AA06 AS01 BB01 BB03 BB06                       BB12 HH00 HH01 HH03 HH05                       HH06 HH08 HH09 HH10                 5H026 AA06 CC10 CV04 HH03

Claims (8)

[Claims] 1. A honeycomb-shaped support, at least a part of which is made of an airtight solid electrolyte material, a plurality of first gas passages, a plurality of second gas passages, and the first gas flow. A first electrode facing the passage, and a second electrode facing the second gas flow path, and a plurality of single cells by the first electrode, the second electrode and the solid electrolyte material. In the electrochemical device, the thickness a1 of the functional portion of the first electrode that constitutes the unit cell contributes to the series connection of the unit cells of the first electrode. Is less than the thickness b1 of the electrochemical device. 2. A thickness a1 of a functional portion of the first electrode forming the unit cell and a thickness b1 of a connecting portion of the first electrode contributing to series connection of a plurality of unit cells. Device according to claim 1, characterized in that the ratio a1 / b1 is less than or equal to 0.8. 3. The thickness a2 of a functional portion of the second electrode that constitutes the unit cell is smaller than the thickness b2 of a connecting portion of the second electrode that contributes to the series connection of the unit cells. Device according to claim 1 or 2, characterized in that 4. A ratio a2 of a thickness a2 of a functional portion of the second electrode forming the unit cell and a thickness b2 of a connecting portion of the second electrode contributing to series connection of the unit cells. /
Device according to claim 3, characterized in that b2 is less than or equal to 0.8. 5. A honeycomb-shaped support, at least a part of which is made of an airtight solid electrolyte material, a plurality of first gas passages, a plurality of second gas passages, and the first gas flow. A first electrode facing the passage, and a second electrode facing the second gas flow path, and a plurality of single cells by the first electrode, the second electrode and the solid electrolyte material. And a thickness a2 of a functional portion of the second electrode that constitutes the unit cell, the connecting portion of the second electrode contributing to series connection of the unit cells. Is less than the thickness b2 of the electrochemical device. 6. A ratio a2 of a thickness a2 of a functional portion of the second electrode forming the unit cell and a thickness b2 of a connecting portion of the second electrode contributing to series connection of the unit cells. /
The device of claim 5, wherein b2 is 0.8 or less. 7. The device according to claim 1, wherein the support is provided with an interconnector layer made of an airtight electronically conductive material. 8. The device according to claim 7, wherein the first gas flow path and the second gas flow path are surrounded by the solid electrolyte material and the interconnector layer, respectively.