JP2009122093A - Electrochemical cell and oxygen enrichment machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide reliable electrochemical cell which can inhibit peeling of each electrode film under high temperature atmosphere during cell operation to stably obtain high level of transmitted gas. <P>SOLUTION: The electrochemical cell comprises an ionic-conductive electrolyte substrate 1 equipped with electrodes 2 and 3 on its both side faces. The electrodes 2 and 3 consist of reaction electrode films 21, 31 used as gas transmitting section formed on the above electrolyte substrate, porous electrode films for power feeding 22a, 32a formed so as to cover those reaction electrode films, and dense electrode films for wiring 22b, 32b extracted from the above porous electrode films outside the above reaction electrode films. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrochemical cell that is used in an oxygen enricher or the like and performs an electrochemical reaction as electrons are transferred, and particularly relates to an electrode structure of an electrochemical cell.

  Conventionally, an oxygen enricher that separates and selectively extracts oxygen from an oxygen-containing mixed gas such as air by an electrochemical reaction has been known. In recent years, the above-mentioned oxygen enricher has been installed in home appliances such as air conditioners. Attempts have been made to create a simple oxygen-enriched atmosphere in the room.

The oxygen enricher includes an electrochemical cell (oxygen permeable electrochemical cell) in which a pair of positive and negative electrodes are arranged on both the front and back surfaces of a solid electrolyte having oxygen ion conductivity. By applying a DC voltage between the positive and negative electrodes of the chemical cell, the solid electrolyte becomes oxygen from one side (negative electrode side to which negative voltage is applied) to the other side (positive side to which positive voltage is applied). It functions to function as an oxygen permeable membrane that allows permeation.
That is, in the electrochemical cell having the above configuration, by supplying an oxygen-containing mixed gas (for example, air) to the negative electrode side, oxygen molecules (O ₂ ) in the air receive electrons on the negative electrode side and receive oxygen ions (O ^{2 -} ) Is ionized, and this oxygen ion (O ²⁻ ) moves as a current in the solid electrolyte to the positive electrode side, where electrons are emitted on the positive electrode side to return to oxygen molecules again.
By utilizing such a property of the solid electrolyte and separating oxygen selectively from the oxygen-containing mixed gas, air with a high oxygen concentration can be obtained.

FIG. 3 shows a general electrode structure of an electrochemical cell, and each electrode (positive electrode, negative electrode) is formed on an ion conductive electrolyte substrate 1 and a reaction electrode film 21 serving as an electrochemical reaction field; A porous electrode film 22a formed on the reaction electrode film 21 for power supply and a dense electrode film 22b drawn out from the porous electrode film 22a to the electrolyte substrate 1 for wiring.
Here, for example, LSGMC: (LaSr) (GaMgCo) O ₃ is used for the electrolyte substrate 1, and for example, SSC: (SmSr) CoO ₃ is used for the reaction electrode 21, and the porous electrode film 22a and For example, Ag particles are used for the dense electrode film 22b.

By the way, as shown in FIG. 3, the electrode portion of the electrochemical cell has a structure in which electrode films having different thermal expansion coefficients are overlapped in three layers, so that the thermal expansion of each electrode film is performed in a high-temperature atmosphere during cell operation. There is a drawback that strain (thermal strain) due to thermal stress caused by the difference in coefficients tends to concentrate at the same position in the stacking direction.
When thermal strain concentrates at one position of the electrode film, in particular, the porous electrode film made of Ag particles having a large particle size is peeled off from the reaction electrode film, which hinders power supply to the reaction electrode film. If the power supply is not performed reliably, the electrochemical reaction at the electrode portion becomes unstable and the gas permeation ability is lowered, which causes a problem that high oxygen concentration air cannot be stably obtained.

For example, Patent Document 1 and Patent Document 2 are disclosed as electrode structures of electrochemical cells. Patent Document 1 describes a structure in which a second electrode film is disposed on a first electrode film, and a lead film for connection is disposed adjacent to these electrode films. Patent Document 2 describes a structure on a gas detection substrate. Describes a structure in which a porous electrode and a dense electrode for connection are arranged.
JP 2007-212280 A JP 2000-227409 A

  The present invention has been made in view of the above-described problems. A highly reliable electrochemical cell capable of preventing the peeling of the electrode film due to thermal stress and stably obtaining a high-concentration permeated gas, and the use thereof are provided. The purpose is to provide an oxygen enricher.

In other words, the electrochemical cell according to claim 1 is an electrochemical cell in which electrodes are arranged on both front and back surfaces of an electrolyte substrate having ion conductivity, and the electrode is a gas formed on the electrolyte substrate. A reaction electrode film serving as a transmission portion, a first electrode film for power feeding formed so as to cover the reaction electrode film, and the first electrode film electrically connected to the first electrode film, and outside the reaction electrode film, the first electrode film It is characterized by comprising a second electrode film for wiring drawn out from the electrode film.
Here, the electrochemical cell means a cell that undergoes an electrochemical reaction with the exchange of electrons, and in addition to an oxygen permeable cell, a power generation cell that generates power using an oxidant gas and a fuel gas, or electrolyzes water. Electrolytic cells are included.

According to a second aspect of the present invention, in the electrochemical cell according to the first aspect, the first electrode film is formed of a porous electrode film, and the second electrode film is formed of a dense electrode film. It is characterized by being.
Here, a noble metal material having a large average particle diameter of 10 to 20 μm is used for the porous electrode film, and a small particle diameter having an average particle diameter of 0.5 to 2.0 μm is used for the dense electrode film. Noble metal materials are used. In addition, the average particle diameter of each said electrode film is based on Microtrac method.
Ag, Au, Pt or the like can be used as the noble metal material.

  The invention described in claim 3 is characterized in that, in the electrochemical cell according to claim 1 or 2, the corner portion of the electrode film is chamfered.

  According to a fourth aspect of the present invention, there is provided the electrochemical cell according to any one of the first to third aspects, wherein the electrochemical cell has electrodes on both sides of an electrolyte substrate having oxygen ion conductivity. It is characterized by being an oxygen permeable cell.

  An oxygen enricher according to claim 5 is characterized by using the electrochemical cell according to claim 4.

According to invention of Claims 1-4, the 1st electrode film for electric power feeding is formed on the reaction electrode film used as a gas permeation | transmission part, and on the 1st electrode film outside the reaction electrode film used as a gas non-permeation part Since the second electrode film for wiring is more drawn, the conventional structure in which a part of these electrode films overlaps three layers in the laminating direction is used. An electrode structure can be formed so as to overlap each other.
With such an electrode structure, it is possible to disperse the generation position of the thermal stress caused by the difference in thermal expansion coefficient of each electrode film in a high temperature atmosphere at the time of cell operation, so that each electrode film is peeled off due to thermal strain. It is possible to prevent the power supply to the cell. As a result, it is possible to stably obtain a high concentration of permeated gas (high oxygen concentration air in the oxygen permeable cell according to claim 4) by an always stable electrochemical reaction (electrode reaction).

  Moreover, since the 1st electrode film used as a gas permeation | transmission part was formed with the porous electrode film like invention of Claim 2, sufficient gas permeability can be ensured with electronic conductivity, and also Since the second electrode film serving as a power supply path to the porous electrode film is formed of a dense electrode film, power can be supplied at a high current density even if the dense electrode film is formed in an elongated electrode pattern. Also from the surface, a permeation gas having a high acid concentration can be stably obtained by a stable electrochemical reaction.

  According to the invention described in claim 3, since chamfering is performed on the corners of the electrode film, it is possible to prevent thermal stress from concentrating on the corners of the electrode film. Can be prevented more reliably.

  Further, according to the invention described in claim 5, by using the oxygen permeable electrochemical cell having the above-described configuration, a high-performance and highly reliable oxygen in which air having a high oxygen concentration can be stably obtained over a long period of time. An enricher can be provided.

Hereinafter, an embodiment of an electrochemical cell according to the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 shows an electrochemical cell according to the present embodiment, (a) is a longitudinal sectional view, (b) is a plan view, and FIG. 2 is a principal longitudinal sectional view showing the structure of the electrode portion of FIG. Yes.

As shown in FIG. 1, the electrochemical cell according to the present embodiment includes a thin plate-like electrolyte substrate 1 (solid electrolyte) having oxygen ion conductivity, and a pair of electrodes 2 and 3 formed on both front and back surfaces. Is an oxygen permeable cell.
Each of the electrodes 2 and 3 includes a reaction electrode film 21 (31) on the outside of the electrolyte substrate 1 and a power supply electrode film 22 (32) on the outside thereof. The power supply electrode film 22 (32) is formed of the reaction electrode film 21 ( 31) and a porous electrode film 22a (32a) for power feeding formed so as to cover, and electrically connected to the porous electrode film 22a (32a) outside the reaction electrode film 21 (31) and an electrolyte. It is composed of a dense electrode film 22b (32b) for wiring drawn out to the substrate 1.
The reaction electrode film 21 (31) is an electrode that serves as an electrochemical reaction field, and is an electrode through which oxygen permeates during cell operation.

Here, the electrolyte substrate 1 has a lanthanum gallate system such as (LaSr) (GaMg) O ₃ , (LaSr) (GaMgCo) O ₃ , (LaSr) (GaMgNi) O ₃ , (LaSr) (GaMgFe) O _3, etc. The reaction electrode film 21 (31) is made of a composite metal oxide material having electron conductivity and ion conductivity such as (SmSr) CoO ₃ , (LaBa) CoO ₃ , and (LaSr) CoO _3. Used for the power supply electrode film 22 (32) is a noble metal particle having excellent heat resistance such as Ag, Au, Pt or the like.
Among these, the above-mentioned noble metal material having a large particle diameter is used for the porous electrode film 22a (32a), and the above-mentioned noble metal material having a small particle diameter is used for the dense electrode film 22b (32b).

  Each of these electrode films is applied on the electrolyte substrate 1 having a thickness of about 30 to 200 μm in order by applying a paste prepared by kneading each electrode material powder with a solvent or a binder, for example, by a screen printing method, It can be formed by firing. The thickness of each electrode 2 and 3 is about 10 to 20 μm.

  And the electrochemical cell of the said structure is the low potential electrode surface (negative electrode 3) of the electrolyte substrate 1 by applying a DC voltage between the electrodes 2 and 3 in 400-800 degreeC high temperature atmosphere. Acts as an oxygen permeable membrane that selectively permeates only oxygen from the oxygen-containing mixed gas (for example, air) from the side toward the other high potential electrode surface (positive electrode 2), and has a higher oxygen concentration than the positive electrode 2 side. You can get air.

  In this case, as shown in FIG. 1A, the positive terminal of the DC power source V is connected to the dense electrode film 22b on the positive electrode 2 side by the lead wire 8, and the porous electrode is interposed through the dense electrode film 22b. Connected to the membrane 22a. On the other hand, the negative terminal of the DC power source V is connected to the dense electrode film 32b on the negative electrode 3 side by the lead wire 9, and is connected to the porous electrode film 32a through the dense electrode film 32b.

  Although not shown in the drawing, an oxygen enricher having an arbitrary capacity is configured by arranging a plurality of electrochemical cells having the above configuration on an insulating support substrate in a state where all of the electrodes on the gas permeation side face the same direction. be able to. In this case, the dense electrode film 22b (32b) can also be used as an electrode pattern for connection between electrochemical cells.

As described above, according to the present embodiment, with respect to the feeding electrode film 22 (32), the oxygen permeable part is constituted by the porous electrode film 22a (32a), and the other gas non-permeable part is the dense electrode film 22b (32b). In the conventional structure, the reaction electrode film 21 (31), the porous electrode film 22a (32a), and the dense electrode film 22b (32b) partially overlap each other in three layers. In addition, an electrode structure in which a part of each electrode film overlaps two layers in the stacking order can be obtained.
As a result, it is possible to disperse the generation points of thermal stress caused by the difference in thermal expansion coefficient of each electrode film in a high temperature atmosphere at the time of cell operation for each layer. Separation of the electrode films 22a and 32a) can be prevented, and power supply to the cell is reliably performed. As a result, air with a high oxygen concentration can be stably obtained by an always stable electrochemical reaction (electrode reaction).
Furthermore, as shown in FIG. 1A and FIG. 2, by applying chamfering (C processing or R processing) to the corners of each electrode film, thermal stress is concentrated on the corners of the electrode film. Since it can prevent, peeling of the electrode film by thermal distortion can be prevented more reliably.

  Further, by forming the gas permeable portion of the feeding electrode film 22 (32) serving as the current path of the DC power source V with the porous electrode film 22a (32a), sufficient gas permeability is ensured together with the electron conductivity. The electrode pattern for supplying power to the porous electrode film 22a (32a) is formed by the dense electrode film 22b (32b), so that the dense electrode film 22b (32b) is elongated for wiring. Even when the electrode pattern is formed, power can be supplied at a high current density. Also from this aspect, air having a high oxygen density can be stably obtained by a stable electrochemical reaction.

  Therefore, by using the oxygen permeable electrochemical cell having such a configuration, it is possible to provide a high-performance and highly reliable oxygen enricher that can stably obtain air having a high oxygen concentration over a long period of time.

The electrochemical cell which concerns on this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a top view. The principal part longitudinal cross-sectional view of FIG. The principal part longitudinal cross-sectional view of the conventional electrochemical cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte board | substrate 2 Positive electrode 3 Negative electrode 21, 31 Reaction electrode film | membrane 22, 32 Feed electrode film | membrane 22a, 32a 1st electrode film (porous electrode film)
22b, 32b Second electrode film (dense electrode film)

Claims (5)

An electrochemical cell comprising electrodes disposed on both front and back surfaces of an electrolyte substrate having ion conductivity,
The electrode is a reaction electrode film serving as a gas permeable portion formed on the electrolyte substrate, a first electrode film for power feeding formed so as to cover the reaction electrode film, and an electrical connection to the first electrode film And a second electrode film for wiring drawn out from the first electrode film outside the reaction electrode film.   The electrochemical cell according to claim 1, wherein the first electrode film is formed of a porous electrode film, and the second electrode film is formed of a dense electrode film.   The electrochemical cell according to claim 1 or 2, wherein the corner portion of the electrode film is chamfered.   The electrochemical cell according to any one of claims 1 to 3, wherein the electrochemical cell is an oxygen permeable cell in which electrodes are arranged on both front and back surfaces of an electrolyte substrate having oxygen ion conductivity. cell.   An oxygen enricher comprising the electrochemical cell according to claim 4.

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