JP2007100152A - Oxygen pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that the adhesion of a solid electrolyte to a supporting body is weak to easily causing the peel off or the breaking of the solid electrolyte in an oxygen pump. <P>SOLUTION: The heating in the oxygen pump is suppressed by linearly connecting a plurality of pump elements 13 to lower current. The oxygen pump secures a joint surface with the supporting body by miniaturizing an anode film having small effect on the performance and has improved adhesion to the supporting body without deteriorating the performance of the oxygen pump. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oxygen pump that exhausts oxygen from one space or enriches oxygen into one space by electrochemically moving oxygen ions.

  Conventionally, this type of oxygen pump, when using a plurality of solid electrolytes simultaneously, electrically connects the electrode film in the same plane direction to the support member with a lead wire or the like, and applies a power supply voltage in parallel. there were. The area of the electrode film was the same for the anode electrode film and the cathode electrode film. (For example, refer to Patent Document 1).

FIG. 5 is a plan view of the oxygen pump described in Patent Document 1, and FIG. 6 is a cross-sectional view of the oxygen pump. Sixteen oxygen ion conductive solid electrolytes 1 are illustrated and fixed to a support member 2. The lead wires 4 are drawn out from the electrode films 3 having the same area and gathered, and connected to the wiring at the same potential. A lead wire 5 is drawn from the wiring and is connected to one pole of the power source. A lead 6 wire similarly drawn from the back surface is connected to the other pole of the power source.
WO96 / 28589 pamphlet

  However, in the conventional configuration, since a plurality of solid electrolytes are connected in parallel, a large current flows through the lead wire in which the lead wires are gathered. Therefore, local heat generation occurred, causing cracks due to thermal strain. In order to prevent this, it is necessary to use a sufficiently thick lead wire or a special lead wire having a small electric resistance. Furthermore, since the joining of different materials between the solid electrolyte and the support causes a large thermal strain when exposed to high temperatures, there is also a problem that the solid electrolyte is easily peeled off or cracked.

  The present invention solves the above-mentioned conventional problems, suppresses local heat generation of the pump element by reducing the current by series connection, and increases the adhesion between the solid electrolyte and the support to increase thermal strain. An object of the present invention is to provide an oxygen pump excellent in reliability with suppressed peeling due to the above.

  In order to solve the above-described conventional problems, an oxygen pump according to the present invention includes a support provided with a plurality of openings, and an oxygen ion conductive solid electrolyte joined by the joined body so as to close the openings. A pump element in which an anode electrode film and a cathode electrode film are formed on both surfaces of the solid electrolyte, the plurality of pump elements are configured to be electrically connected in series, and the outside of the anode electrode film The area in contact with the cathode electrode film is smaller than the area in contact with the outside air of the cathode electrode film.

  By connecting the electrode film on the front surface and the opposite electrode film on the back surface adjacent to each other with a lead wire and connecting the whole in series, the current can be reduced and heat generation can be suppressed. In addition, by reducing the anode electrode film, a bonding area with the support can be secured, and the adhesion with the support can be improved without deteriorating the oxygen pump performance.

The oxygen pump of the present invention suppresses destruction of the solid electrolyte due to thermal strain by reducing the current by connecting a plurality of solid electrolytes provided with a support in series and further increasing the adhesion with the support. It becomes possible.

  According to a first aspect of the present invention, there is provided a support provided with a plurality of openings, an oxygen ion conductive solid electrolyte joined by a joined body so as to close the openings, and anode electrode films on both sides of the solid electrolyte. Each of the plurality of pump elements is configured to be electrically connected in series, and the area of the anode electrode film in contact with the outside air is in contact with the outside of the cathode electrode film. By being configured to be smaller than the area, the current can be reduced and heat generation can be suppressed. In addition, by reducing the area of the anode electrode film that has a small effect on the performance, it is possible to secure a bonding area with the support, thereby enabling an oxygen pump that suppresses breakage due to thermal strain without deteriorating the operating performance. .

  In the second invention, in particular, the opening of the first invention has a lattice shape or a slit shape. The strength against impact is higher when the support and the solid electrolyte are joined only at the periphery than when the whole surface of the solid electrolyte is joined. Further, since the entire surface is covered with the support, the heat distribution of the solid electrolyte is more uniform, and the thermal stress can be kept small. Therefore, an oxygen pump that suppresses breakage due to thermal strain becomes possible.

  In the third invention, in particular, the anode electrode film has an area ratio of 50% or more and less than 100% with respect to the cathode electrode film. On the anode electrode film side, about half of the solid electrolyte substrate can be formed as a bonding portion, so that the adhesion can be improved. Therefore, it is possible to prevent destruction due to thermal strain caused by heating and energization of the oxygen pump.

  In the fourth invention, in particular, the support of the first invention is a metal foil. By using a metal foil, the flexibility of the support can be increased and the thermal strain of the solid electrolyte can be absorbed. That is, an oxygen pump that suppresses breakage due to thermal strain is possible.

  5th invention has the electroconductive joining body electrically connected to the anode electrode film | membrane, and the lead wire connected to the said joining body, and the said lead wire is a cathode electrode film | membrane with respect to a support body. It is the same surface side. By using the lead wire only in one direction on the cathode side, the lead wire does not penetrate the support body or bypass the side surface of the support body, so the space between the anode electrode film side and the cathode electrode film side is completely removed. And gas leakage can be prevented. Further, by taking out the anode current from the surroundings, the concentration of current can be relaxed and heat generation can be suppressed. That is, an oxygen pump that suppresses breakage due to thermal strain is possible.

  In the sixth invention, in particular, the support of the fifth invention is a conductive metal foil, and the metal foil and the joined body are electrically insulated by an insulator. By taking out the anode current from the surroundings, current concentration can be alleviated and heat generation can be suppressed, and by using the metal foil, the flexibility of the support can be increased and the thermal strain of the solid electrolyte can be absorbed. That is, an oxygen pump that suppresses breakage due to thermal strain is possible.

  In the seventh invention, in particular, the metal foil of the fourth or sixth invention is a ferritic stainless steel containing aluminum. By using a ferritic stainless steel containing aluminum, it has excellent characteristics against high-temperature oxidation, and can maintain stable characteristics for long-term use at a high temperature around 800 ° C.

In an eighth invention, the electrode film of the first invention is composed of two layers of a metal oxide in contact with a solid electrolyte and a noble metal in contact with the metal oxide. Since the surface heat distribution can be made more uniform by the noble metal formed on the entire surface of the solid electrolyte, an oxygen pump in which destruction due to thermal strain is suppressed is possible.

  In the ninth invention, lanthanum gallate is used particularly for the first or second solid electrolyte material. Lanthanum gallate is a perovskite complex metal oxide mainly composed of lanthanum and gallium and has oxygen ion conductivity at 400 ° C. or higher. Therefore, since sufficient capability can be obtained even by maintaining the operating temperature of the oxygen pump at a relatively low temperature of about 600 ° C., the temperature can be lowered and deterioration against heat can be suppressed.

  The tenth aspect of the invention is a glass sintered body, in particular, with respect to the insulator of the sixth aspect of the invention. A glass insulator can sufficiently cope with a high temperature of several hundred degrees used in an oxygen pump, and since the insulator is a very thin film, the flexibility of the metal foil is rarely lost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIGS. 1A and 1B are cross-sectional structural views of a pump element according to the first embodiment of the present invention. Here, the area of the anode electrode film 7 is configured to be smaller than the area of the cathode electrode film 8, and is bonded to the support 2 on the side of the anode electrode film 7.
As the solid electrolyte 1, metal oxides such as zirconia and ceria are used, and lanthanum gallate is particularly preferable. Among them, a perovskite oxide having a composition of lanthanum-strontium-gallium-magnesium (LSGMO) is most useful because of its high transport number. In the embodiment, a square LSGMO having a side of 30 mm and a thickness of 0.15 mm is used.

  The anode electrode film 7 and the cathode electrode film 8 each have a two-layer structure (not shown), and a metal oxide of samarium-strontium-cobalt (SSCO) is used for the lower layer and gold is used for the upper layer. However, as an embodiment of the present invention, the electrode film may have a single-layer structure, and silver, platinum, an alloy of gold and palladium, or an alloy of silver and palladium may be used as an electrode material at that time. . These electrode films are formed by screen printing, electrodeposition, vapor deposition, or sputtering, but screen printing is excellent in terms of cost. The electrode film in this embodiment forms a printed film by screen printing, and after drying, the SSCO is fired at 1100 ° C. to a thickness of 15 to 25 μm, and gold is fired at 800 ° C. to a thickness of 5 to 5 10 μm was obtained.

  As the support 2, an alumina ceramic plate having a thickness of 1 mm was used, and the solid electrolyte 1 and gold were sintered around the opening 9 and joined together by a joined body 10.

  FIG. 2A is a plan view of six pump elements joined to the support 2. FIG. 2B is a cross-sectional view of the pump element portion at two locations, and the cathode electrode film 8 adjacent to the anode electrode film 7 on the lower surface is connected via the through hole 12 of the support 2 by the lead wire 11. Has been. As a whole, six pump elements are connected in series.

  As the lead wire 11, a gold wire having a diameter of 0.2 mm was used, and bonding at the ends was fixed by sintering at 750 ° C. using a gold paste.

  In this example, the outer periphery of the bonding portion on the anode electrode film side was formed with three types of widths of 1.5 mm, 3.0 mm, and 5.0 mm. In this case, the area of the anode electrode film was 100%, 76%, and 48% of the area of the cathode electrode film, respectively.

FIG. 3 shows a schematic cross-sectional configuration diagram of an operation model of an oxygen pump in which the pump element 13 is incorporated. Around one support 2 serving as a space partitioning means for nine solid electrolytes, it is fixed to the housing 14 by an electrically insulating gas sealant (not shown). The lead wire 11 is connected to a power source (not shown). In addition, above and below the oxygen pump, a heat insulating material 15 formed in a plate shape mainly composed of silica and alumina is disposed, and a heater 16 is disposed therein.

  The operation and action of the oxygen pump configured as described above will be described.

  First, an opening sandwiched between the heat insulating materials 15 is heated to 650 ° C. by the heater 16 embedded in the heat insulating material on the cathode electrode film 8 side in the pump element of FIG. Thereafter, when a voltage is applied to the pump element 13 via the lead wire 11, oxygen in the space on the cathode electrode film 8 side is ionized on the cathode electrode film 8. The oxygen ions move in the solid electrolyte 1 by the electric field and reach the anode electrode film 7 on the opposite side. After that, electrons are released to become oxygen molecules again and released into the space.

  In the present embodiment, as a result of applying a voltage of 1.0 V to three types in which the area of the anode electrode film 7 was changed, a current of about 10.0 A all flowed. The estimated oxygen generation is about 330 cc. However, at 300 hours after energization, the smaller the area of the anode electrode film, the higher the voltage and the lower the current, and the deterioration occurred. When the pump element after the energization test was observed, the joint between the support and the solid electrolyte was partially peeled off. In addition, when the oxygen generation amount of about 330 cc in this embodiment is performed in parallel connection, a large current of about 90 A needs to flow.

  As described above, according to the present embodiment, even when the area of the anode electrode film 7 in contact with the space is 50% smaller than the area of the cathode electrode film 8 in contact with the space by an area ratio, the initial oxygen generation amount does not decrease, Rather, since the bonding area can be increased, the durability against heat can be improved.

(Embodiment 2)
FIG. 4 (a) is a plan view of six pump elements connected in series in the second embodiment of the present invention. FIGS. 4B and 4C are cross-sectional views of the pump element portion at two locations. The cathode electrode film 8 adjacent to the conductive joint connected to the anode electrode film 7 on the lower surface is a lead wire 11. Connected by. Further, the area of the anode electrode film 7 is configured to be smaller than the area of the cathode electrode film 8, and the anode 2 is joined to the support 2 on the anode electrode film 7 side. Hereinafter, a description will be added with a focus on differences from the first embodiment.

  In FIG. 4B, the support 2 is a ceramic plate as in the first embodiment, but in FIG. 4C, it is a metal foil. The metal foil and the conductive joined body are insulated by a glass insulator. Here, although Fe-20Cr-5Al material was used as the metal foil, the material is not limited to this, and other metal foil materials can be used as long as the material has durability against high-temperature oxidation. . However, at present, ferritic stainless steel containing aluminum has excellent characteristics against high-temperature oxidation. Furthermore, it is possible to add a rare earth metal for the purpose of improving the high temperature oxidation resistance. Moreover, although 12 micrometers in thickness was used, it is thought that 5-20 micrometers is preferable as a metal foil member. Further, although a glass sintered body is used as the insulator, the invention is not limited to this, and a ZrO 2 film or an Al 2 O 3 film can be used.

  In this example, the outer periphery of the junction part on the anode electrode film side was formed with three types of widths of 3.0 mm. In this case, the area of the anode electrode film is 76% of the area of the cathode electrode film.

  The schematic cross-sectional configuration diagram of the operation model of the oxygen pump incorporating the pump element is the same as that of FIG. 3, but the lead wire 11 is drawn out only from the cathode electrode film side (not shown). .

  The oxygen pump configured as described above was operated in the same manner as in the first embodiment. As a result, when a voltage of 1.0 V was applied, a current of about 10.0 A flowed. The estimated oxygen generation is about 330 cc. When the pump elements of the types shown in FIGS. 4B and 4C were observed after energization for 500 hours, microcracks were generated in the solid electrolyte in which the support in FIG. 4B was a ceramic.

  As described above, according to the present embodiment, even if the support 2 is made of metal foil and the area of the anode electrode film 7 is reduced for bonding, the initial oxygen generation amount does not decrease, but rather the bonding area is increased. As a result, it was possible to improve durability against heat because of its flexibility and resistance to thermal strain.

  As described above, the oxygen pump according to the present invention can reduce the circuit current, and thus can be used as a household electric appliance. Examples of such electrical appliances include health equipment such as an oxygen enricher and oxygen aspirator, air conditioning equipment such as an air purifier and an air conditioner, and products in which they are incorporated as part of the function.

(A) And (b) is sectional drawing of the pump element in Embodiment 1, 2 of invention (A) is the top view of the pump element in Embodiment 1 of invention, (b) is sectional drawing of (a). Sectional drawing of the operation | movement model of the oxygen pump in Embodiment 1, 2 of invention (A) is a top view of the pump element in Embodiment 2 of invention, (b) and (c) are sectional drawings of (a). Plan view of an oxygen pump according to a conventional patent document 1 Sectional view of an oxygen pump according to the conventional patent document

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid electrolyte 2 Support body 7 Anode electrode film 8 Cathode electrode film 9 Opening part 11 Lead wire 13 Pump element 14 Case 15 Heat insulating material 16 Heater

Claims (10)

A support provided with a plurality of openings, an oxygen ion conductive solid electrolyte joined by a joined body so as to close the openings, and an anode electrode film and a cathode electrode film formed on both sides of the solid electrolyte, respectively. A pump element, a power source for applying a voltage to the pump element via a lead wire, and a heater disposed opposite to the pump element, wherein the polarities of the plurality of electrode films are on the support. The plurality of pump elements are configured to be electrically connected in series, and the area of the anode electrode film in contact with the outside air is smaller than the area of the cathode electrode film in contact with the outside air. And oxygen pump. The oxygen pump according to claim 1, wherein the opening has a lattice shape or a slit shape. The oxygen pump according to claim 1 or 2, wherein the anode electrode film has an area ratio of 50% or more and less than 100% with respect to the cathode electrode film. The oxygen pump according to claim 1, wherein the support is a metal foil. It has a conductive joined body electrically connected to the anode electrode film and a lead wire connected to the joined body, and the lead wire is on the same surface side as the cathode electrode film with respect to the support. The oxygen pump according to claim 1. The oxygen pump according to claim 5, wherein the support is a conductive metal foil, and the metal foil and the joined body are electrically insulated by an insulator. The oxygen pump according to claim 4 or 6, wherein the metal foil is a ferritic stainless steel containing aluminum. The oxygen pump according to claim 1, wherein the electrode film is composed of two layers of a metal oxide in contact with a solid electrolyte and a noble metal in contact with the metal oxide. The oxygen pump according to claim 1 or 2, wherein the solid electrolyte is lanthanum gallate. The oxygen pump according to claim 6, wherein the insulator is a sintered body of glass.

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