Electrochemical cell

Abstract

The present invention provides an electrochemical cell wherein: a pair of electrodes are connected by the intermediary of a solid electrolyte; and at least one of the electrodes is supported by a metal support. The solid electrolyte is configured as a dense ion conductive layer; at least one of the electrodes is configured as a porous ion conductive layer that has oxygen ion conductivity; and the metal support is configured as a porous electron conductive layer that supports the porous ion conductive layer. In addition, a porous oxidation prevention layer is arranged between the porous ion conductive layer and the porous electron conductive layer; and a catalyst material is loaded such that the porous ion conductive layer, the porous oxidation prevention layer and the porous electron conductive layer are connected.

Description

Technical Field

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[0001] The present invention relates to an electrochemical cell.

Background Art

[0002] In an electrochemical cell having a solid electrolyte such as a solid oxide fuel cell (SOFC) or a solid oxide electrolysis cell (SOEC), when a metal support for supporting an electrode (air electrode) exposed in an oxidizing atmosphere is provided, the air electrode and the surrounding metal support are liable to be oxidized and deteriorated. Therefore, the mechanical strength is reduced, which may cause cell damage.

[0003] JP2009 - 59697A discloses a solid oxide fuel cell having a metal support layer supporting a cathode (air electrode) layer. This solid oxide fuel cell prevents oxidation degradation of the cathode layer and the metal support layer by forming a barrier layer on the surfaces of the cathode layer and the metal support layer.

Summary of the Invention

[0007] [Figure 1] Figure 1 is a schematic diagram of an electrochemical cell according to an embodiment of the present invention. [Figure 2] Figure 2 is an enlarged view of the porous oxidation-preventive layer. [Figure 3] Figure 3 is a schematic diagram illustrating the conduction of electrons and oxygen ions in the porous electron conduction layer, the porous oxidation prevention layer, and the porous ion conduction layer. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings and other figures.

[0009] Figure 1 is a schematic diagram of the electrochemical cell 100 according to this embodiment. The electrochemical cell 100 has a pair of electrodes 20 and 30 connected via a solid electrolyte 10. In this embodiment, the electrochemical cell 100 is described as a solid oxide fuel cell (SOFC) that extracts electricity from air (oxygen) and fuel (hydrogen), but it is not limited to this. For example, the electrochemical cell 100 may be a solid oxide electrolytic cell (SOEC) that extracts oxygen and hydrogen by electrolyzing water with electricity. Also, the electrochemical cell 100 of this embodiment is mainly installed in vehicles, etc., but it is not limited to this.

[0010] As shown in Figure 1, the electrochemical cell 100 comprises a solid electrolyte 10, a pair of electrodes 20 and 30 connected via the solid electrolyte 10, a metal support 40 provided to support one of the electrodes 20, and an antioxidant layer 50 disposed between the electrode 20 and the metal support 40. A catalyst material 60 is also supported on the electrochemical cell 100.

[0011] The solid electrolyte 10 is composed of a dense ion-conducting layer formed of an oxide having oxygen ion conductivity (hereinafter, the solid electrolyte 10 is also referred to as the dense ion-conducting layer 10), and is sandwiched between a pair of electrodes 20 and 30. As the oxide, for example, yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (SSZ), samarium-doped ceria (SDC), gadolium-doped ceria (GDC), lanthanum-strontium-magnesium gallate (LSGM), etc. can be used, but are not limited to these.

[0012] Electrode 20 is an oxidizing electrode (air electrode, cathode electrode) exposed to an oxygen atmosphere, and is composed of a porous ion-conducting layer having oxygen ion conductivity (hereinafter, electrode 20 is also referred to as porous ion-conducting layer 20). The porous ion-conducting layer 20 is provided so as to be in contact with one surface of the dense ion-conducting layer 10. As the material constituting the porous ion-conducting layer 20, for example, oxides made of lanthanum, strontium, manganese, cobalt, zirconium, cerium, etc. can be used, but are not limited to these. In the porous ion-conducting layer 20, a reduction reaction occurs that reduces oxygen in the cathode gas (air).

[0013] Electrode 30 is the fuel electrode (anode electrode) and is made of a porous material. Electrode 30 can be formed from, for example, a noble metal material with catalytic function such as nickel and a mixed cermet material such as yttria-stabilized zirconia (YSZ), but is not limited to these. Furthermore, electrode 30 is positioned in contact with the other surface of the dense ion-conducting layer 10. At electrode 30, an oxidation reaction occurs in which oxide ions that have conducted through the dense ion-conducting layer 10 oxidize the anode gas containing hydrogen, etc. The electrochemical cell 100 generates electricity based on the electrode reactions at the cathode electrode (electrode 20) and the anode electrode (electrode 30). If the electrochemical cell 100 is a solid oxide electrolytic cell (SOEC), electricity is supplied to the electrochemical cell 100 to electrolyze water, thereby extracting hydrogen (fuel) at electrode 30 (fuel electrode) and oxygen at electrode 20 (air electrode).

[0014] The metal support 40 is provided so as to be in contact with one surface of the oxidation-preventive layer 50, which will be described later, and supports the porous ion-conducting layer 20 and the oxidation-preventive layer 50. That is, the metal support 40 functions as a structural member to reinforce the strength of the electrochemical cell 100. The metal support 40 is also configured as a porous electron-conducting layer having electron conductivity (hereinafter, the metal support 40 will also be referred to as the porous electron-conducting layer 40). Specific materials that constitute the porous electron-conducting layer 40 include, for example, metals such as stainless steel, iron, and nickel, but are not limited to these.

[0015] The oxidation prevention layer 50 is a porous component for preventing oxidation of the porous ion conduction layer 20 and the porous electron conduction layer 40. It is positioned between the porous ion conduction layer 20 and the porous electron conduction layer 40 to isolate them (hereinafter, the oxidation prevention layer 50 will also be referred to as the porous oxidation prevention layer 50). The porous oxidation prevention layer 50 is made of a material that has no oxygen ion conductivity, or whose oxygen ion conductivity is lower than that of the other layers (dense ion conduction layer 10, porous ion conduction layer 20, electrode 30, porous electron conduction layer 40). This inhibits the conduction of oxygen ions in the porous ion conduction layer 20 to the porous electron conduction layer 40. Further details of the oxidation prevention layer 50 will be described later.

[0016] The catalyst material 60 has catalytic activity in the reduction reaction of oxygen and can be selected from, but is not limited to, metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, copper, silver, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum, as well as alloys thereof. Furthermore, the catalyst material 60 has electron conductivity and is supported so as to connect the porous electron conductive layer 40, the oxidation prevention layer 50, and the porous ion conductive layer 20.

[0017] In the electrochemical cell 100 configured as described above, electrons supplied from the porous electron conduction layer 40 are supplied to the porous ion conduction layer 20 via the catalyst material 60, and oxygen is reduced in the porous ion conduction layer 20.

[0018] Incidentally, in electrochemical cells with solid electrolytes, such as solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs), the electrodes (air electrodes) exposed to an oxidizing atmosphere and the metal supports that support them are susceptible to oxidative degradation. In particular, when oxygen ions are conducted from the air electrode to the metal support, oxidative degradation is promoted at the interface between the air electrode and the metal support, which can lead to delamination or cracking of the air electrode and metal support at the interface, potentially damaging the cell.

[0019] In contrast, in the present embodiment, an antioxidant layer 50 is provided between the porous ion conductive layer 20 (air electrode) and the porous electron conductive layer 40 (metal support), separating the porous ion conductive layer 20 (air electrode) from the porous electron conductive layer 40 (metal support). Therefore, the conduction of oxygen ions in the porous ion conductive layer 20 to the porous electron conductive layer 40 is inhibited. As a result, oxidation degradation at the bonding interface between the porous ion conductive layer 20 (air electrode) and the porous electron conductive layer 40 (metal support) is suppressed, and peeling and cracking at the bonding interface between the porous ion conductive layer 20 (air electrode) and the porous electron conductive layer 40 (metal support) are prevented. That is, damage to the electrochemical cell 100 due to oxidation degradation is prevented.

[0020] Hereinafter, the details of the porous antioxidant layer 50 will be described.

[0021] FIG. 2 is an enlarged view of the porous antioxidant layer 50.

[0022] The porous antioxidant layer 50 is prepared, for example, by kneading raw material particles and a binder. As shown in FIG. 2, a catalyst material 60 having electronic conductivity is supported on the porous antioxidant layer 50 so as to be connected to the porous electron conductive layer 40 and the porous ion conductive layer 20.

[0023] One surface of the porous antioxidant layer 50 is sintered to the porous ion conductive layer 20, and the other surface is sintered to the porous electron conductive layer 40, so that the porous antioxidant layer 50 is disposed between the porous ion conductive layer 20 and the porous electron conductive layer 40.

[0024] As described above, the porous antioxidant layer 50 is formed of a material having no oxygen ion conductivity or having lower oxygen ion conductivity than other layers (dense ion conductive layer 10, porous ion conductive layer 20, electrode 30, porous electron conductive layer 40). Specifically, for example, it is formed of zirconia (doped zirconia) doped with 3 mol% or less of yttria as an additive material. By setting the additive material to 3 mol% or less, it is possible to keep the oxygen ion conductivity low while maintaining sufficient strength.

[0025] More specifically, the porous oxidation prevention layer 50 is formed so as to contain 70% or more of a material having no oxygen ion conductivity or having lower oxygen ion conductivity than other layers at the interface connecting to the porous ion conduction layer 20. For example, the porous oxidation prevention layer 50 is formed so as to contain 70% or more of a material formed of zirconia (doped zirconia) doped with 3 mol% or less of yttria as an additive material at the interface connecting to the porous ion conduction layer 20. Thereby, diffusion of oxygen ions in the porous ion conduction layer 20 toward the porous oxidation prevention layer 50 can be more inhibited, and it is possible to more prevent oxygen ions from conducting to the porous electron conduction layer 40 and the porous electron conduction layer 40 from deteriorating by oxidation. Also, in portions other than the interface with the porous ion conduction layer 20, other materials can be used, and the degree of freedom in material selection is increased.

[0026] Further, the porous oxidation prevention layer 50 contains a metal component of the same kind as the material constituting the porous ion conduction layer 20 (for example, zirconium, cerium, etc.), and is configured such that the difference between the thermal expansion coefficient of the material constituting the porous oxidation prevention layer 50 and the thermal expansion coefficient of the material constituting the porous ion conduction layer 20 is 20% or less. By making the difference in thermal expansion coefficient 20% or less, it is possible to prevent the two layers from peeling off when the porous oxidation prevention layer 50 and the porous ion conduction layer 20 are sintered. Also, since the porous oxidation prevention layer 50 contains a metal component of the same kind as the porous ion conduction layer 20, the sintering strength of the two layers is improved.

[0027] More specifically, the porous oxidation prevention layer 50 is configured to contain 70% or more of a material having a difference in thermal expansion coefficient of 20% or less from the material constituting the porous ion conduction layer 20 and containing a metal component of the same kind as the material constituting the porous ion conduction layer 20 at the interface connecting to the porous ion conduction layer 20. Thereby, peeling between the porous oxidation prevention layer 50 and the porous ion conduction layer 20 during sintering can be prevented, the sintering strength of the two layers can be improved, and in portions other than the interface with the porous ion conduction layer 20, other materials can be used, so the degree of freedom in material selection is increased.

[0028] Furthermore, the porous antioxidant layer 50 is configured to include a metal material. As a result, the bonding between the porous antioxidant layer 50 and the porous electron conductive layer 40 (metal support) becomes a metal-to-metal bonding, thereby improving the bonding strength.

[0029] More specifically, the porous antioxidant layer 50 is configured such that the metal material ratio is 30% or more at the interface connecting it to the porous electron conduction layer 40. By making the metal material ratio 30% or more at the interface with the porous electron conduction layer 40, the bonding strength between the porous antioxidant layer 50 and the porous electron conduction layer 40 is further improved. Furthermore, in areas other than the interface with the porous electron conduction layer 40, the metal material ratio can be reduced to further lower the oxygen ion conductivity.

[0030] Furthermore, as the metal material used in the porous oxidation-preventive layer 50, for example, stainless steel (aluminum-containing SUS) containing 2 to 6 wt% aluminum (Al) can be used. By using aluminum, the oxidation resistance of the metal in the porous oxidation-preventive layer 50 can be increased, and the deterioration of the porous oxidation-preventive layer 50 can be prevented.

[0031] Next, the porous oxidation-preventive layer 50 is configured such that its thickness t is 50% or more of the average particle size of the metal particles contained in the porous electron conduction layer 40. If the thickness t of the porous oxidation-preventive layer 50 is less than 50% of the average particle size of the metal particles contained in the porous electron conduction layer 40, there is a risk that the porous electron conduction layer 40 will penetrate the porous oxidation-preventive layer 50 and connect to the porous ion conduction layer 20 during the fabrication of the electrochemical cell 100. If the porous electron conduction layer 40 connects to the porous ion conduction layer 20, oxidative degradation will occur at the connection interface between the porous electron conduction layer 40 and the porous ion conduction layer 20, increasing the risk of damage to the electrochemical cell 100. Therefore, in this embodiment, by configuring the thickness t of the porous oxidation-preventive layer 50 to be 50% or more of the average particle size of the metal particles contained in the porous electron conduction layer 40, it is prevented that the porous electron conduction layer 40 will penetrate the porous oxidation-preventive layer 50 and connect to the porous ion conduction layer 20 during the fabrication of the electrochemical cell 100. Figure 2 is a schematic representation of the porous antioxidant layer 50, and the thickness t of the porous antioxidant layer 50 is shown to be considerably larger than the actual thickness of the metal particles contained in the porous electron conductive layer 40.

[0032] As described above, the porous oxidation-preventive layer 50 is composed of a material that has affinity with the porous ion-conducting layer 20 and further inhibits the conduction of oxygen ions near the interface where it connects with the porous ion-conducting layer 20, and a material that has affinity with the porous electron-conducting layer 40 near the interface where it connects with the porous electron-conducting layer 40. Furthermore, the porous oxidation-preventive layer 50 is configured to a thickness such that the porous electron-conducting layer 40 does not penetrate the porous oxidation-preventive layer 50 when the electrochemical cell 100 is fabricated.

[0033] Furthermore, as a method for changing the ratio of each material near the interface, for example, a method can be used in which the porous oxidation-preventive layer 50 is made by dividing it into multiple layers with different material ratios and joining these multiple layers together, but this method is not limited to this.

[0034] Figure 3 is a schematic diagram illustrating the conduction of electrons and oxygen ions in the porous electron conduction layer 40, the porous oxidation prevention layer 50, and the porous ion conduction layer 20.

[0035] As shown in Figure 3, an electron-conductive catalyst material 60 is supported in the porous ion-conducting layer 20, the porous oxidation-preventive layer 50, and the porous electron-conducting layer 40, connecting these three layers. Therefore, when electrons are supplied to the porous electron-conducting layer 40 from a circuit or the like, these electrons are conducted from the electron-conductive porous electron-conducting layer 40 to the catalyst material 60 and supplied to the three-phase interface exposed to the catalyst material 60, the porous ion-conducting layer 20, and the gas phase. In other words, electrons supplied from the porous electron-conducting layer 40 are conducted to the porous ion-conducting layer 20 without being hindered by the porous oxidation-preventive layer 50.

[0036] Furthermore, when electrons are supplied to the three-phase interface, which is exposed to the porous ion-conducting layer 20, the catalyst material 60, and the gas phase, oxygen in the air (cathode gas) is reduced at the three-phase interface to become oxygen ions.

[0037] Here, a porous antioxidant layer 50, which inhibits the conduction of oxygen ions, is positioned between the porous electron conduction layer 40 and the porous ion conduction layer 20 so as to isolate them. As a result, oxygen ions in the porous ion conduction layer 20 are conducted only towards the dense ion conduction layer 10 (see Figure 1) and not into the porous electron conduction layer 40. Consequently, oxidative degradation of the junction interface between the porous ion conduction layer 20 and the porous electron conduction layer 40 due to oxygen ion conduction is suppressed.

[0038] Furthermore, in order to prevent oxidation of the porous electron conduction layer 40 and the porous ion conduction layer 20 by oxygen in the air, a barrier layer made of a barrier material having oxygen ion conductivity and electron conductivity may be provided on the surfaces of the porous electron conduction layer 40 and the porous ion conduction layer 20. The barrier layer can be provided by impregnating the porous electron conduction layer 40 and the porous ion conduction layer 20 with the barrier material.

[0039] According to the electrochemical cell 100 of the above-described embodiment, the following effects can be obtained.

[0040] In the electrochemical cell 100, a porous antioxidant layer 50 is placed between the porous ion conduction layer 20 and the porous electron conduction layer 40 (metal support), and a catalyst material 60 is supported so as to connect the porous ion conduction layer 20, the porous antioxidant layer 50, and the porous electron conduction layer 40. By providing the porous antioxidant layer 50 in this way, the conduction of oxygen ions in the porous ion conduction layer 20 to the porous electron conduction layer 40 is inhibited. Therefore, oxidative degradation at the junction interface between the porous ion conduction layer 20 and the porous electron conduction layer 40 is suppressed, and delamination and cracking at the junction interface between the porous ion conduction layer 20 and the porous electron conduction layer 40 are prevented. In other words, damage to the electrochemical cell 100 due to oxidative degradation is prevented.

[0041] Furthermore, since the catalyst material 60 is supported so as to connect the porous ion conduction layer 20, the porous antioxidant layer 50, and the porous electron conduction layer 40, electrons supplied from the porous electron conduction layer 40 can be conducted to the porous ion conduction layer 20 without being obstructed by the porous antioxidant layer 50.

[0042] In the electrochemical cell 100, the porous ion conduction layer 20 constitutes an air electrode exposed to an oxidizing atmosphere, and a porous oxidation-preventive layer 50 is placed between the porous ion conduction layer 20 (air electrode) and the porous electron conduction layer 40 (metal support). By placing the porous oxidation-preventive layer 50 on the air electrode side, where the risk of oxidative degradation is high, damage to the electrochemical cell 100 due to oxidative degradation can be prevented more effectively.

[0043] The electrochemical cell 100 has a porous antioxidant layer 50 made of a material that has no oxygen ion conductivity or lower conductivity than the other layers. This further inhibits the diffusion of oxygen ions in the porous ion conductive layer 20 towards the porous electron conductive layer 40, and further prevents oxidative degradation at the interface between the porous ion conductive layer 20 and the porous electron conductive layer 40.

[0044] The electrochemical cell 100 has a porous antioxidant layer 50 made of doped zirconia doped with an additive material containing 3 mol% or less yttria. This makes it possible to maintain the strength of the porous antioxidant layer 50 while keeping its oxygen ion conductivity low.

[0045] In the electrochemical cell 100, the porous antioxidant layer 50 contains 70 percent or more of a material with no or lower oxygen ion conductivity than the other layers at the interface connecting to the porous ion conductive layer 20. This further inhibits the diffusion of oxygen ions in the porous ion conductive layer 20 toward the porous antioxidant layer 50, thereby better preventing oxidative degradation at the interface between the porous ion conductive layer 20 and the porous electron conductive layer 40. Furthermore, since other materials can be used in areas other than the interface with the porous ion conductive layer 20, the degree of freedom in material selection is increased.

[0046] The electrochemical cell 100 contains at least 70 percent of a material made of doped zirconia doped with 3 mol% or less of an additive at the interface where the porous antioxidant layer 50 connects with the porous ion conductive layer 20. This allows for greater inhibition of the diffusion of oxygen ions from within the porous ion conductive layer 20 toward the porous antioxidant layer 50 while maintaining the strength of the porous antioxidant layer 50.

[0047] In the electrochemical cell 100, the difference in thermal expansion coefficients between the material constituting the porous antioxidant layer 50 and the material constituting the porous ion conductive layer 20 is 20% or less. By constructing the porous antioxidant layer 50 with a material whose thermal expansion coefficient difference from that of the porous ion conductive layer 20 is 20% or less, it is possible to prevent the porous antioxidant layer 50 and the porous ion conductive layer 20 from delaminating when they are sintered together.

[0048] The electrochemical cell 100 contains the same type of metal component in the porous ion conduction layer 20 as in the porous ion conduction layer 50. This improves the sintering strength between the porous ion conduction layer 50 and the porous ion conduction layer 20, preventing delamination between them.

[0049] The electrochemical cell 100 has a porous antioxidant layer 50 that, at the interface where it connects to the porous ion conductive layer 20, has a thermal expansion coefficient difference of 20% or less between the porous antioxidant layer 50 and the material constituting the porous ion conductive layer 20, and contains 70% or more of a material that has the same type of metal component as the material constituting the porous ion conductive layer 20. This prevents delamination between the porous antioxidant layer 50 and the porous ion conductive layer 20 during sintering, improves the sintering strength of both layers, and allows the use of other materials in areas other than the interface with the porous ion conductive layer 20, thus increasing the freedom of material selection.

[0050] The electrochemical cell 100 has a porous antioxidant layer 50 that contains a metal material. As a result, the bonding between the porous antioxidant layer 50 and the porous electron conduction layer 40 (metal support) becomes a metal-to-metal bonding, improving the bonding strength. Therefore, delamination of the porous antioxidant layer 50 and the porous electron conduction layer 40 is prevented.

[0051] In the electrochemical cell 100, the ratio of metal material is 30% or more at the interface where the porous antioxidant layer 50 connects with the porous electron conduction layer 40. This further improves the bonding strength between the porous antioxidant layer 50 and the porous electron conduction layer 40. Furthermore, in parts of the porous antioxidant layer 50 other than the interface with the porous electron conduction layer 40, the ratio of metal material can be reduced to further lower the oxygen ion conductivity.

[0052] The electrochemical cell 100 has a porous antioxidant layer 50 which contains a metallic material containing 2-6 wt% aluminum. This enhances the oxidation resistance of the metal within the porous antioxidant layer 50 and prevents the deterioration of the porous antioxidant layer 50.

[0053] In the electrochemical cell 100, the thickness t of the porous antioxidant layer 50 is 50 percent or more of the average particle size of the metal particles constituting the porous electron conduction layer 40. This prevents the porous electron conduction layer 40 from penetrating the porous antioxidant layer 50 and connecting to the porous ion conduction layer 20 during the fabrication of the electrochemical cell 100.

[0054] In this embodiment, the porous ion conducting layer 20 is used as the air electrode, and the porous oxidation-preventive layer 50 is provided on the air electrode side, but the embodiment is not necessarily limited to this. That is, a porous electron conducting layer (metal support) having electron conductivity may be provided on the fuel electrode (electrode 30) side, and the porous oxidation-preventive layer may be placed between the electrode 30 and the porous electron conducting layer. For example, when a vehicle equipped with the electrochemical cell 100 is stopped, oxygen may flow into the fuel electrode side, so there is a risk of oxidative degradation on the fuel electrode side as well. However, by providing a porous oxidation-preventive layer on the air electrode side, damage to the electrochemical cell 100 due to oxidative degradation can be prevented.

[0055] Furthermore, in this embodiment, the porous oxidation-preventive layer 50 is composed of a material that has no oxygen ion conductivity or lower conductivity than the other layers, but is not necessarily limited to this. For example, only a part of the porous oxidation-preventive layer 50 may be composed of a material that has no oxygen ion conductivity or lower conductivity than the other layers, and the other part may be composed of a material that has the same oxygen ion conductivity as the other layers. In this case as well, the conduction of oxygen ions can be inhibited, and oxidative degradation at the junction interface between the porous ion conduction layer 20 and the porous electron conduction layer 40 can be suppressed. Moreover, the entire porous oxidation-preventive layer 50 may be composed of a material that has the same oxygen ion conductivity as the other layers. In this case as well, compared to the case where the porous ion conduction layer 20 and the porous electron conduction layer 40 are directly joined, the conduction of oxygen ions from the porous ion conduction layer 20 to the porous electron conduction layer 40 can be suppressed.

[0056] Furthermore, the specific materials, percentages, thermal expansion coefficients, and thickness of the porous antioxidant layer 50 shown in this embodiment represent preferred configurations and are not necessarily limited thereto. In other words, the porous antioxidant layer 50 can have any configuration as long as it can suppress the conduction of oxygen ions from the porous ion conduction layer 20 to the porous electron conduction layer 40.

[0057] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Claims

1. An electrochemical cell in which a pair of electrodes are connected via a solid electrolyte, and at least one of the electrodes is supported by a metal support, The solid electrolyte is configured as a dense ion-conducting layer, At least one of the electrodes is configured as a porous ion-conducting layer having oxygen ion conductivity, The metal support is configured as a porous electron conduction layer that supports the porous ion conduction layer, A porous antioxidant layer is disposed between the porous ion conducting layer and the porous electron conducting layer. An electron-conducting catalyst material is supported on the porous ion-conducting layer, the porous oxidation-preventing layer, and the porous electron-conducting layer so as to connect them. Electrochemical cell.

2. An electrochemical cell according to claim 1, The porous ion-conducting layer constitutes an air electrode exposed to an oxidizing atmosphere. Electrochemical cell.

3. An electrochemical cell according to claim 1 or 2, The porous antioxidant layer is made of a material that has no oxygen ion conductivity or has lower conductivity than the other layers. Electrochemical cell.

4. An electrochemical cell according to any one of claims 1 to 3, The porous antioxidant layer is made of doped zirconia to which 3 mole percent or less of yttria has been added. Electrochemical cell.

5. An electrochemical cell according to any one of claims 1 to 4, The porous antioxidant layer contains 70 percent or more of a material that has no oxygen ion conductivity or lower conductivity than the other layers at the interface connecting to the porous ion conductive layer. Electrochemical cell.

6. An electrochemical cell according to any one of claims 1 to 5, The porous antioxidant layer contains 70 percent or more of a material made of doped zirconia with 3 mole percent or less of yttria added at the interface connecting to the porous ion conductive layer. Electrochemical cell.

7. An electrochemical cell according to any one of claims 1 to 6, The difference in thermal expansion coefficients between the material constituting the porous oxidation-preventive layer and the material constituting the porous ion-conducting layer is 20 percent or less. Electrochemical cell.

8. An electrochemical cell according to any one of claims 1 to 7, The material constituting the porous antioxidant layer contains the same type of metal component as the material constituting the porous ion conductive layer. Electrochemical cell.

9. An electrochemical cell according to any one of claims 1 to 8, The porous oxidation-preventive layer, at the interface connecting to the porous ion-conducting layer, has a thermal expansion coefficient difference of 20 percent or less from the material constituting the porous ion-conducting layer, and contains 70 percent or more of a material that includes the same type of metal component as the material constituting the porous ion-conducting layer. Electrochemical cell.

10. An electrochemical cell according to any one of claims 1 to 9, The porous antioxidant layer includes a metal material. Electrochemical cell.

11. An electrochemical cell according to any one of claims 1 to 10, The porous oxidation-preventive layer has a metal material ratio of 30 percent or more at the interface connecting to the porous electron-conducting layer. Electrochemical cell.

12. An electrochemical cell according to any one of claims 1 to 11, The porous antioxidant layer comprises a metal material containing 2 to 6 weight percent of aluminum. Electrochemical cell.

13. An electrochemical cell according to any one of claims 1 to 12, The thickness of the porous antioxidant layer is 50 percent or more of the average particle size of the metal particles constituting the porous electron conduction layer. Electrochemical cell.

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