electrodes and electrochemical cells for electrochemical cells

Abstract

The present invention provides an electrochemical cell electrode that appropriately possesses electronic conductivity, catalytic function, and ionic conductivity. [Solution] The electrochemical cell electrode 10 disclosed herein includes an electron conduction portion 12 mainly composed of an electron conduction catalyst and an ion conduction portion 14. A first layer 10a is formed in the region including the upper surface 10U of the electrochemical cell electrode 10. This first layer 10a includes the electron conduction portion 12 and substantially does not include the ion conduction portion 14. On the other hand, a second layer 10b is formed in the region including the lower surface 10D of the electrochemical cell electrode 10. In the width direction X of this second layer 10b, the electron conduction portion 12 and the ion conduction portion 14 are formed alternately. With this configuration, materials can be arranged according to the differences in required performance in the thickness direction, so that electron conductivity, catalytic function, and ion conductivity can be appropriately exhibited.

Description

[Technical Field]

[0001] This invention relates to an electrode for an electrochemical cell and an electrochemical cell using said electrode. [Background technology]

[0002] Solid oxide fuel cells (SOFCs) have advantages such as high power generation efficiency and low environmental impact, and demand has been increasing in recent years. Typically, an SOFC has a layered structure in which a fuel electrode (anode), a solid electrolyte layer, and an air electrode (cathode) are stacked in that order. The fuel electrode and air electrode of the SOFC are electrically connected to an external load. In an SOFC with this structure, oxygen (O2) in the oxygen-containing gas at the air electrode is converted into electrons (e - ) receives oxygen ions (O 2- This results in the following: The oxygen ions then pass through the solid electrolyte layer as charge carriers. The oxygen ions that have moved to the fuel electrode then react with the fuel gas (e.g., hydrogen (H2)) supplied to the fuel electrode. At this time, water vapor (H2O) is produced at the fuel electrode, and electrons are released from the fuel electrode to the external load, generating electrical energy.

[0003] On the other hand, the cell structure used as an SOFC can also function as a Solid Oxide Electrolysis Cell (SOEC) by applying current in the reverse direction. Specifically, when current is applied with water vapor supplied to the fuel electrode of the cell structure described above, oxygen gas is produced at the air electrode and hydrogen gas is produced at the fuel electrode. This allows hydrogen gas to be generated from water vapor. Furthermore, the cell structure described above uses protons (for example, hydrogen ions (H)) as charge carriers. +This can also be applied to proton-conducting ceramic fuel cell cells (PCFCs) and proton-conducting ceramic electrolysis cells (PCECs). In this specification, cell structures capable of functioning as SOFCs, SOECs, PCFCs, and PCECs are referred to as "electrochemical cells."

[0004] The electron-conducting catalyst, which is the main component of the electrodes (fuel electrode and air electrode) of this electrochemical cell, has a catalytic function that promotes the oxidation or reduction of gas (fuel gas or oxygen-containing gas) and an electron-conducting function that conducts electrons. In recent years, electrodes for electrochemical cells have sometimes had an ion-conducting material having ion conductivity (oxygen ion conductivity or proton conductivity) added as a minor component. This improves the ion conductivity inside the electrode, thereby improving the power generation efficiency. An example of such an electrode is disclosed in Patent Document 1. In the electrode described in Patent Document 1, an electron-conducting material (electron-conducting catalyst) forms an electrically continuous pattern of electron-conducting paths between ion-conducting paths made of an ion-conducting material. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-71537 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Figure 8 shows a schematic cross-sectional view of the conventional electrochemical cell electrode described above. In the electrode 210 shown in Figure 8, ion conduction sections 212 containing an ion conductive material and electron conduction sections 214 containing an electron conductive material are alternately formed in a predetermined direction (width direction X). It is believed that an electrode 210 with this configuration can exhibit suitable power generation performance because many ion conduction paths are formed by the ion conduction sections 212.

[0007] However, in order to form an ion conduction path as shown in Figure 8, it is necessary to form many ion conduction portions 212 within the electrode 210. In this case, the amount of electron conduction portion 214, which contains the electron conductive material that is the original main component of the electrode 210, decreases, which may lead to a decrease in electron conductivity and catalytic function.

[0008] This invention has been made in consideration of the above problems, and aims to provide an electrode for an electrochemical cell that appropriately possesses electronic conductivity, catalytic function, and ionic conductivity. [Means for solving the problem]

[0009] In solving the above-mentioned problems, the inventors focused on the differences in required performance in the thickness direction of electrodes for electrochemical cells (hereinafter also simply referred to as "electrodes"). Specifically, one region in the thickness direction of the electrode (hereinafter referred to as the "first layer") is the region that is electrically connected to an external load when an electrochemical cell is constructed, and therefore requires excellent electronic conductivity. Furthermore, since this first layer is also the part that comes into direct contact with oxygen-containing gas (or fuel gas), it is also required to have excellent catalytic function. On the other hand, the region opposite the first layer (hereinafter referred to as the "second layer") is positioned opposite other layers (solid electrolyte layer or reaction inhibitory layer) when an electrochemical cell is constructed. The second layer is required to have excellent ionic conductivity in order to appropriately move ions (oxygen ions or protons) between itself and this opposing layer.

[0010] The electrode for an electrochemical cell disclosed herein is based on the above-described findings. This electrode for an electrochemical cell is a layered electrode used in an electrochemical cell. Such an electrode includes an electron conduction portion mainly composed of an electron conduction catalyst having electron conductivity and catalytic function, and an ion conduction portion mainly composed of an ion conduction material having ion conductivity. In the electrode disclosed herein, a first layer is formed in a region including one end face in the stacking direction, and this first layer includes an electron conduction portion but substantially does not include an ion conduction portion. A second layer is provided in a region including the other end face in the stacking direction, and in this second layer, electron conduction portions and ion conduction portions are alternately formed in a direction along the other end face.

[0011] The first layer of the electrode with the above configuration includes an electron-conducting portion but substantially does not include an ion-conducting portion. As a result, unlike the conventional electrode 210 shown in Figure 8, the main component of the first layer can be an electron-conducting catalyst, thus satisfying the high electron conductivity and catalytic function required for the first layer. On the other hand, the second layer of the electrode disclosed herein includes an ion-conducting portion. As a result, the ion conductivity of the second layer in contact with the opposing layer can be improved. In the second layer of the electrochemical cell electrode disclosed herein, electron-conducting portions and ion-conducting portions are formed alternately. As a result, the uneven distribution of ion-conducting material in specific areas can be prevented, and high ion conductivity can be obtained with a small amount of ion-conducting material. As described above, the electrochemical cell electrode disclosed herein arranges electron-conducting portions and ion-conducting portions according to the differences in required performance in the thickness direction, so that electron conductivity, catalytic function, and ion conductivity can be appropriately exhibited.

[0012] In one preferred embodiment of the electrochemical cell electrode disclosed herein, the ion conductive material is a rare-earth stabilized ceria obtained by doping ceria with a rare-earth oxide. This suppresses the reaction between the electron conduction catalyst and the ion conductive material that generates a high-resistance phase.

[0013] In one preferred embodiment of the electrochemical cell electrode disclosed herein, the electron conduction portion of the second layer contains an ion conductive material as a minor component. The electron conduction catalyst, which is the main component of the electron conduction portion, tends to have a higher coefficient of thermal expansion than the material of the opposing layer (solid electrolyte layer or reaction inhibitory layer) used in the construction of the electrochemical cell. Therefore, if a rapid temperature change occurs after the construction of the electrochemical cell, there is a risk that the electron conduction portion of the second layer and the opposing layer will delaminate. In contrast, by adding an ion conductive material to the electron conduction portion of the second layer, as in this embodiment, the coefficient of thermal expansion of the electron conduction portion can be reduced, thereby suppressing delamination when a rapid temperature change occurs.

[0014] Furthermore, in an embodiment in which the electron conduction portion of the second layer contains an ion conductive material, it is preferable that the electron conduction portion of the second layer is configured such that the content of the ion conductive material increases as it approaches the other end face. The peeling due to the rapid temperature change described above is a phenomenon caused by the difference in the coefficient of thermal expansion between the end face of the electron conduction portion of the second layer and the opposing layer. Therefore, as described above, by increasing the content of the ion conductive material at the end face in contact with the opposing layer, peeling due to rapid temperature changes can be efficiently suppressed.

[0015] Furthermore, in an embodiment in which the electron-conducting portion of the second layer contains an ion-conducting material, it is preferable that the content of the ion-conducting material at the other end face of the electron-conducting portion of the second layer is 40 wt% or more and 60 wt% or less. This makes it possible to more effectively suppress peeling due to rapid temperature changes.

[0016] Furthermore, in one preferred embodiment of the electrochemical cell electrode disclosed herein, the width of the ion-conducting portion of the second layer is 500 μm or more and 1000 μm or less. This allows for a sufficient improvement in the ion conductivity of the second layer.

[0017] Furthermore, in one preferred embodiment of the electrochemical cell electrode disclosed herein, the thickness of the first layer is greater than or equal to the thickness of the second layer. This ensures a sufficient content of the electron conduction catalyst throughout the electrode, thereby securing suitable electron conductivity and catalytic function.

[0018] Also, in an embodiment where the thickness of the first layer is equal to or greater than the thickness of the second layer, the thickness of the first layer is preferably 1 μm or more and 50 μm or less. This can further improve the electron conductivity and catalytic function of the entire electrode. On the other hand, the thickness of the second layer is preferably 1 μm or more and 10 μm or less. This can sufficiently ensure the ion conductivity in the second layer.

[0019] Also, as another aspect of the technology disclosed herein, an electrochemical cell is provided. Such an electrochemical cell includes a fuel electrode to which a fuel gas is supplied, an air electrode to which an oxygen-containing gas is supplied, and a solid electrolyte layer interposed between the fuel electrode and the air electrode. And in the electrochemical cell disclosed herein, either the fuel electrode or the air electrode is the electrode for an electrochemical cell having the above-described configuration, and the second layer of the electrode for an electrochemical cell faces the solid electrolyte layer. Since the electrochemical cell disclosed herein uses the electrode for an electrochemical cell having the above-described configuration, it can exhibit high performance.

[0020] Also, in a preferred embodiment of the electrode for an electrochemical cell disclosed herein, the air electrode is the electrode for an electrochemical cell having the above-described configuration. Further, in such an embodiment, the electron conduction catalyst is preferably a perovskite-type oxide represented by the general formula: ABO3, containing at least one of La and Sr at the A site and at least one of Fe and Co at the B site. The perovskite-type oxide having the above-described configuration can preferably promote the reduction of the oxygen-containing gas, and thus is suitable as an electron conduction catalyst for the air electrode.

[0021] Also, in an embodiment where the electrode for an electrochemical cell having the above-described configuration is used as the air electrode, it is preferable that a reaction inhibition layer mainly composed of an ion conductive material having ion conductivity is interposed between the solid electrolyte layer and the air electrode. This can prevent the electron conduction catalyst of the air electrode and the solid electrolyte layer from reacting to generate a high-resistance phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] [Figure 1]This is a schematic cross-sectional view showing an electrode for an electrochemical cell according to one embodiment. [Figure 2] This is a schematic diagram showing an example of the structure of the second layer in a plan view. [Figure 3] This is a schematic diagram showing an example of the structure of the second layer in a plan view. [Figure 4] This is a schematic side view showing an electrochemical cell according to one embodiment. [Figure 5] This is a side view illustrating the manufacturing procedure for an electrode for an electrochemical cell according to one embodiment. [Figure 6] This is a side view illustrating the manufacturing procedure for an electrode for an electrochemical cell according to one embodiment. [Figure 7] This is a side view illustrating the manufacturing procedure for an electrode for an electrochemical cell according to one embodiment. [Figure 8] This is a schematic cross-sectional view of a conventional electrode for an electrochemical cell. [Modes for carrying out the invention]

[0023] Embodiments of the technology disclosed herein will be described below with reference to the drawings as appropriate. Matters other than those specifically mentioned herein but necessary for implementing the technology disclosed herein (for example, detailed materials and manufacturing methods of each layer excluding the support) can be understood as design matters for those skilled in the art based on prior art. The technology disclosed herein can be implemented based on the content disclosed herein and common technical knowledge in the art. Furthermore, in the following drawings, components and parts that perform the same function are denoted by the same reference numerals and described accordingly, and redundant explanations may be omitted or simplified.

[0024] 1. Electrodes for electrochemical cells An embodiment of the technology disclosed herein will be described below. Figure 1 is a schematic cross-sectional view showing an electrode for an electrochemical cell according to this embodiment. Figures 2 and 3 are schematic diagrams showing an example of the structure of the second layer in a plan view. Figure 4 is a schematic side view showing an electrochemical cell according to this embodiment. In each figure referenced herein, the symbol X indicates the "width direction", the symbol Y indicates the "depth direction", and the symbol Z indicates the "stack direction (thickness direction)". These directions are defined for the convenience of explanation and are not intended to limit the installation direction of the electrochemical cell during manufacturing or use. The electrochemical cell electrode 10 used as the air electrode of the electrochemical cell will be described below.

[0025] As shown in Figure 1, the electrode 10 for the electrochemical cell according to this embodiment (hereinafter also simply referred to as "electrode 10") includes an electron conduction portion 12 and an ion conduction portion 14. This electrode 10 for the electrochemical cell comprises a first layer 10a having the electron conduction portion 12 and a second layer 10b having both the electron conduction portion 12 and the ion conduction portion 14. Each region will be described below.

[0026] (1) Electronic conduction section The electron conduction region 12 is a region mainly composed of an electron conduction catalyst. In this specification, "electron conduction catalyst" refers to an inorganic material that has a predetermined electron conductivity and also has the catalytic activity required for the electrode to be used. Furthermore, in this specification, "mainly composed of an electron conduction catalyst" refers to a state in which the electron conduction region 12 contains 50 wt% or more of the electron conduction catalyst based on its total weight (100 wt%).

[0027] As described above, the electron conduction catalyst is appropriately selected from conventionally known catalyst materials according to the catalytic activity required for the electrode in which it is used. For example, in the air electrode of an electrochemical cell, oxygen (O2) gas is reduced to oxygen ions (O2). 2-A reaction occurs that produces ). For this reason, an inorganic material that promotes the reduction of oxygen gas is used as the electron conduction catalyst for the air electrode. An example of such an electron conduction catalyst for the air electrode is a perovskite-type oxide represented by the general formula: ABO3. The A site of such a perovskite-type oxide contains at least one selected from the group consisting of lanthanide elements (e.g., La, Ce, Pr, etc.) and alkaline earth metal elements (e.g., Sr, Ba, Ra, etc.). On the other hand, the B site contains at least one selected from transition metal elements (e.g., Fe, Co, etc.). Examples of such perovskite-type oxides include LaCoO3, LaFeO3, SrCoO3, SrFeO3, and LaSrCoO3. By using these perovskite-type oxides, an electron conduction section 12 with excellent oxygen ion generation efficiency and electron conductivity can be formed. Note that the perovskite-type oxide with the above configuration may contain trace elements different from the A site element and the B site element, as long as they do not significantly impair electron conductivity or catalytic function.

[0028] (2) Ion conduction section The ion-conducting section 14 is a region mainly composed of an ion-conducting material. In this specification, "ion-conducting material" refers to an inorganic material having the ability to conduct oxygen ions or protons (ionic conductivity). Furthermore, in this specification, "mainly composed of an ion-conducting material" means that the ion-conducting section 14 contains 50 wt% or more of the ion-conducting material based on its total weight (100 wt%). From the viewpoint of further improving the oxygen ion conductivity of the ion-conducting section 14, the content of the ion-conducting material in the ion-conducting section 14 is preferably 60 wt% or more, more preferably 70 wt% or more, even more preferably 80 wt% or more, and particularly preferably 90 wt% or more. On the other hand, the upper limit of the content of the ion-conducting material in the ion-conducting section 14 is not particularly limited and may be 100 wt%, 99 wt% or less, or 98 wt% or less.

[0029] The ion conductive material can be any conventionally known ion conductive material that can be added to electrodes for electrochemical cells without any particular limitations. Preferably, the ion conductive material is a metal oxide with low reactivity with the electron conduction catalyst. This suppresses the formation of a high-resistance phase due to the reaction between the electron conduction catalyst and the ion conductive material. For example, when constructing an electrochemical cell (such as an SOFC) using oxygen ions as carriers, it is preferable to use stabilized ceria (CeO2) doped with rare earth oxides as the ion conductive material. Such stabilized ceria has high oxygen ion conductivity and low reactivity with perovskite-type oxides, making it suitable as an ion conductive material for the air electrode of an SOFC. Specific examples of this stabilized ceria include gadolina-stabilized ceria (GDC), lanthania-stabilized ceria (LDC), samaria-stabilized ceria (SDC), and yttria-stabilized ceria (YDC). Furthermore, in an electrochemical cell (such as a PCFC) using protons as carriers, hydrogen ions (H) are introduced from the opposing layer of electrode 10. + Protons such as ) are supplied. In this case, it is preferable to use BaCeO3-based oxides or BaZrO3-based oxides, which have excellent proton conductivity, as ion conductive materials.

[0030] (3) 1st layer Next, the first layer 10a having the electron-conducting portion 12 described above will be explained. This first layer 10a is formed in a region including one end face in the stacking direction Z (hereinafter referred to as the "upper surface 10U"). As shown in Figure 4, the upper surface 10U of the electrode 10 is to which the current collector 150 is attached when the electrochemical cell 100 is constructed and is electrically connected to the external load 200. For this reason, the first layer 10a including the upper surface 10U is required to have better electron conductivity than other regions of the electrode 10. Furthermore, since this first layer 10a is also the part that comes into direct contact with the oxygen-containing gas, it is also required to have excellent catalytic function to promote the reduction of the oxygen-containing gas. In response to these performance requirements, the first layer 10a in this embodiment is configured to include the electron-conducting portion 12 and substantially omit the ion-conducting portion 14. This makes it possible to make the electron-conducting catalyst the main component of the first layer 10a, thereby satisfying the high electron conductivity and catalytic function required for the first layer 10a.

[0031] In this specification, "substantially free of ion-conducting regions" means that regions primarily composed of ion-conducting material (ion-conducting regions) are intentionally not formed. Therefore, if components that can be interpreted as ion-conducting material are inevitably and in trace amounts due to raw materials or manufacturing processes, it is interpreted that a first layer substantially free of ion-conducting regions has been formed. For example, if the content of ion-conducting material relative to the total weight (100 wt%) of the first layer is 1 wt% or less (preferably 0.1 wt% or less, more preferably 0.01 wt% or less, even more preferably 0.001 wt% or less, and particularly preferably 0.0001 wt% or less), it can be said that "a first layer substantially free of ion-conducting regions has been formed." Even if the first layer contains ion-conducting material in such trace amounts, the required electronic conductivity and catalytic function of the first layer can be sufficiently ensured.

[0032] Furthermore, as described above, the electron conduction portion 12 is a region containing 50 wt% or more of the electron conduction catalyst. However, since high electron conductivity and catalytic function are required in the first layer 10a, it is preferable that the electron conduction portion 12a of the first layer 10a contains a larger amount of the electron conduction catalyst. Specifically, the content of the electron conduction catalyst in the electron conduction portion 12a of the first layer 10a is preferably 80 wt% or more, more preferably 85 wt% or more, even more preferably 90 wt% or more, and particularly preferably 95 wt% or more. This makes it possible to form an electrochemical cell electrode 10 with particularly excellent electron conductivity and catalytic function. On the other hand, the upper limit of the content of the electron conduction catalyst in the electron conduction portion 12a is not particularly limited and may be 100 wt%, 99 wt% or less, or 98 wt% or less.

[0033] Furthermore, the thickness t1 of the first layer 10a is preferably greater than or equal to the thickness t2 of the second layer 10b, which will be described later. This ensures a sufficient content of the electron conduction catalyst throughout the electrode 10, thereby obtaining excellent electron conductivity and catalytic function. From the viewpoint of further improving the catalytic function and electron conductivity throughout the electrode 10, the thickness t1 of the first layer 10a is preferably 1 μm or more, more preferably 3 μm or more, even more preferably 5 μm or more, and particularly preferably 10 μm or more. On the other hand, the upper limit of the thickness t1 of the first layer 10a is not particularly limited and may be 100 μm or less, 75 μm or less, 50 μm or less, or 25 μm or less.

[0034] (2)Second layer Next, the second layer 10b of the electrode 10 according to this embodiment has both an electron conduction portion 12 and an ion conduction portion 14. This second layer 10b is formed in a region including the other end face in the stacking direction Z (hereinafter referred to as the "bottom surface 10D"). As shown in Figure 4, the bottom surface 10D of the electrode 10 is positioned opposite the reaction suppression layer 130 when constructing the electrochemical cell 100. Therefore, the second layer 10b is required to have high ionic conductivity to promote the movement of ions (oxygen ions, hydrogen ions, etc.) between it and the reaction suppression layer 130. To meet this performance requirement, the second layer 10b of the electrode 10 according to this embodiment has electron conduction portions 12 and ion conduction portions 14 alternately formed in a predetermined direction along the bottom surface 10D (width direction X in Figure 1). Specifically, by forming ion conduction portions 14 in the second layer 10b, the ionic conductivity of the second layer 10b can be improved. However, if the ion conduction portion 14 is formed over the entire area of ​​the second layer 10b, the electron conduction catalyst will no longer be present in the second layer 10b, and therefore the second layer 10b will cease to function as an air electrode 140 (see Figure 4). For this reason, the second layer 10b in this embodiment has both an electron conduction portion 12 and an ion conduction portion 14. Furthermore, in this embodiment, the electron conduction portion 12 and the ion conduction portion 14 are formed alternately in the width direction X. This prevents the ion conduction material from being unevenly distributed in specific areas, so that high ion conductivity can be obtained with a small amount of ion conduction material. As a result, a second layer 10b with suitable ion conductivity can be formed despite the presence of an electron conduction portion 12.

[0035] In addition, the second layer 10b is such that, in a cross-sectional view as shown in Figure 1, the electron conduction portion 12b and the ion conduction portion 14 are arranged alternately in a predetermined direction along the lower surface 10D of the electrode 10. In other words, the arrangement positions of the electron conduction portion 12b and the ion conduction portion 14 in a plan view are not particularly limited. For example, as shown in Figure 2, when forming linear electron conduction portion 12 and ion conduction portion 14 along the depth direction Y, these linear electron conduction portion 12 and ion conduction portion 14 are formed alternately in the width direction X. This allows for the uniform formation of the ion conduction portion 14 on the lower surface 10D of the electrode 10, thereby improving ion conductivity. Another example of the arrangement positions of the electron conduction portion 12b and ion conduction portion 14 in a plan view is the form shown in Figure 3. In the second layer 10b shown in Figure 3, the planar rectangular electron conduction portion 12 and ion conduction portion 14 are arranged in a checkerboard pattern. In this configuration, the arrangement of the ion conducting portion 14 on the lower surface 10D of the electrode 10 becomes more uniform, thereby further improving ion conductivity.

[0036] Furthermore, the width w1 of the electron conduction portion 12b of the second layer 10b (see Figure 2) is preferably 300 μm or more, more preferably 400 μm or more, even more preferably 500 μm or more, and particularly preferably 600 μm or more. As the width w1 of the electron conduction portion 12b increases, the electron conductivity and catalytic function of the second layer 10b tend to improve. Also, the upper limit of the width w1 of the electron conduction portion 12b is not particularly limited and may be 1500 μm or less, 1250 μm or less, 1000 μm or less, or 750 μm or less. On the other hand, the width w2 of the ion conduction portion 14 is preferably 300 μm or more, more preferably 400 μm or more, even more preferably 500 μm or more, and particularly preferably 600 μm or more. As the width w2 of the ion conduction portion 14 increases, the ion conductivity of the second layer 10b tends to improve. Furthermore, the upper limit of the width w2 of the ion conducting section 14 is not particularly limited and may be 1500 μm or less, 1250 μm or less, 1000 μm or less, or 750 μm or less.

[0037] Furthermore, unlike the electron conduction portion 12a of the first layer 10a, it is preferable that the electron conduction portion 12b of the second layer 10b contains an ion conductive material as a secondary component. Specifically, the electron conduction catalyst, which is the main component of the electron conduction portion 12, tends to have a higher coefficient of thermal expansion than the material to which the electrode 10 is connected (in this embodiment, the reaction suppression layer 130). Therefore, if a rapid temperature change occurs after the electrochemical cell 100 is constructed, there is a risk that the electrode 10 and the reaction suppression layer 130 will delaminate. In contrast, by adding an ion conductive material to the electron conduction portion 12b of the second layer 10b, the coefficient of thermal expansion of the electron conduction portion 12b can be reduced. This makes it possible to approximate the coefficients of thermal expansion of the electron conduction portion 12b of the second layer 10b and the reaction suppression layer 130, thereby suppressing delamination due to rapid temperature changes.

[0038] The peeling caused by the rapid temperature change described above is a phenomenon caused by the difference in thermal expansion coefficients between the end face of the electron conduction portion 12b of the second layer 10b and the opposing layer (reaction suppression layer 130). Considering this, it is preferable that the electron conduction portion 12b of the second layer 10b is configured such that the content of the ion conductive material increases as it approaches the lower surface 10D of the electrode 10. This allows for sufficient maintenance of the electron conduction catalyst content throughout the electron conduction portion 12b of the second layer 10b while suppressing peeling between the electrode 10 and the opposing layer. The content of the ion conductive material at the lower surface 10D of the electron conduction portion 12b of the second layer 10b is preferably 30 wt% or more, more preferably 35 wt% or more, even more preferably 40 wt% or more, and particularly preferably 45 wt% or more. This allows for more effective suppression of peeling between the electrode 10 and the opposing layer. On the other hand, the content of the ion conductive material on the lower surface 10D of the electron conductive portion 12b of the second layer 10b is preferably 70 wt% or less, more preferably 65 wt% or less, even more preferably 60 wt% or less, and particularly preferably 55 wt% or less. This ensures sufficient electron conductivity and catalytic function in the second layer 10b.

[0039] Furthermore, considering the addition of an ion conductive material to prevent peeling, the content of the electron conductive catalyst in the electron conductive portion 12b of the second layer 10b may be less than that of the electron conductive portion 12a of the first layer 10a. The specific content of the electron conductive catalyst in this electron conductive portion 12b is preferably 55 wt% or more, more preferably 60 wt% or more, even more preferably 65 wt% or more, and particularly preferably 70 wt% or more. This ensures sufficient electron conductivity and catalytic function in the second layer 10b. On the other hand, considering the addition of an ion conductive material to prevent peeling, the content of the electron conductive catalyst in the electron conductive portion 12b is preferably 85 wt% or less, and particularly preferably 80 wt% or less.

[0040] Furthermore, the thickness t2 of the second layer 10b is preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 1.5 μm or more, and particularly preferably 2 μm or more. This ensures sufficient ionic conductivity between the electrode 10 and the opposing layer (reaction suppression layer 130). On the other hand, the thickness t2 of the second layer 10b is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and particularly preferably 4 μm or less. This ensures sufficient content of the electron conduction catalyst in the entire electrode 10, thereby improving catalytic function and electron conductivity.

[0041] 2. Electrochemical cell Next, an electrochemical cell 100 constructed using the electrochemical cell electrode 10 with the above configuration will be described. As shown in Figure 4, the electrochemical cell 100 according to this embodiment comprises a fuel electrode 110, a solid electrolyte layer 120, a reaction inhibitory layer 130, and an air electrode 140. Specifically, in the electrochemical cell 100, the solid electrolyte layer 120 is interposed between the fuel electrode 110 and the air electrode 140. Furthermore, in the electrochemical cell 100 according to this embodiment, the reaction inhibitory layer 130 is interposed between the air electrode 140 and the solid electrolyte layer 120. Each configuration will be described below. Note that the following description assumes that the electrochemical cell 100 is used as a solid oxide electrolytic cell (SOEC).

[0042] (1)Fuel electrode The fuel electrode 110 is a porous layer with multiple pores. When the electrochemical cell 100 is used as an SOFC, fuel gas (hydrogen-containing gas) is supplied to the fuel electrode 110. Examples of fuel gas supplied to the fuel electrode 110 include hydrogen (H2) gas, hydrocarbon gas (e.g., methane (CH4) gas), and ammonia (NH3) gas. A current collector 160 is attached to the lower surface 110D of the fuel electrode 110. The fuel electrode 110 is electrically connected to the external load 200 via this current collector 160.

[0043] When this electrochemical cell 100 is used as an SOFC, the fuel electrode 110 receives oxygen ions (O) supplied from the air electrode 140 via the solid electrolyte layer 120. 2- ) reacts with the fuel gas to generate electrons. For this reason, the fuel electrode 110 contains an electron conduction catalyst as its main component, which promotes the oxidation of the fuel gas. Examples of such electron conduction catalysts for fuel electrodes include metals such as nickel (Ni), copper (Cu), gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), cobalt (Co), lanthanum (La), strontium (Sr), and titanium (Ti), as well as metal oxides containing these metal elements. Among the above-mentioned metal elements, transition metal elements (such as Ni) and platinum group elements (such as Ru) are preferred from the viewpoint of ensuring high catalytic function. In particular, nickel oxide (NiO) is suitable as an electron conduction catalyst for fuel electrodes because it can exhibit stable catalytic function and is inexpensive. The fuel electrode 110 may also contain an ion conductive material having oxygen ion conductivity as a minor component. When nickel oxide or the like is used as an electron conduction catalyst for the fuel electrode, stabilized zirconia, obtained by doping zirconia (ZrO2) with at least one of the following as an ion conduction material: yttria (Y2O3), calcia (CaO), scandia (Sc2O3), magnesia (MgO), ytterbia (Yb2O3), ervia (Er2O3), etc., can be suitably used.

[0044] (2) Solid electrolyte layer The solid electrolyte layer 120 is an ion-conducting layer interposed between the fuel electrode 110 and the air electrode 140. That is, the solid electrolyte layer 120 conducts charge carriers (oxygen ions (O) between the fuel electrode 110 and the air electrode 140. 2- ), hydrogen ions (H + It has the role of transmitting (etc.). Furthermore, when the electrochemical cell 100 is used as an SOFC, the solid electrolyte layer 120 also has the role of separating the oxygen-containing gas supplied to the air electrode 140 from the hydrogen-containing gas supplied to the fuel electrode 110. For this reason, the solid electrolyte layer 120 is formed as a dense layer that blocks the flow of gas between the fuel electrode 110 and the air electrode 140. Note that the structure (thickness, porosity, etc.) of the solid electrolyte layer 120 can be any general structure without particular limitations and does not limit the technology disclosed herein, so a detailed explanation is omitted.

[0045] The solid electrolyte material, which is the main component of the solid electrolyte layer 120, is a metal oxide with particularly excellent ionic conductivity. For example, the solid electrolyte layer 120 of an SOFC uses a solid electrolyte material with excellent oxygen ion conductivity. Such a solid electrolyte material for an SOFC is preferably a metal oxide doped with a predetermined element as a stabilizer. Examples of such solid electrolyte materials include stabilized zirconia obtained by doping zirconia (ZrO2) with at least one of the following: yttria (Y2O3), calcia (CaO), scandia (Sc2O3), magnesia (MgO), ytterbia (Yb2O3), ervia (Er2O3), etc. More specific examples include yttria-stabilized zirconia (YSZ) and scandia-stabilized zirconia (ScSZ).

[0046] (3) Reaction inhibitory layer The reaction suppression layer 130 is a layer interposed between the solid electrolyte layer 120 and the air electrode 140. The reaction suppression layer 130 suppresses the reaction between the solid electrolyte layer 120 and the air electrode 140 to form a high-resistance phase. Furthermore, in order to ensure ionic conductivity between the air electrode 140 and the solid electrolyte layer 120, the reaction suppression layer 130 is required to have high ionic conductivity. That is, the reaction suppression layer 130 is formed from an inorganic material that has low reactivity with the electron conduction catalyst of the air electrode 140 and excellent ionic conductivity. The ionic conductive material that is the main component of the ionic conduction section 14 can be used as the main component of this reaction suppression layer 130. For example, when constructing an SOFC, examples of ionic conductive materials include gadolina-stabilized ceria (GDC), lanthania-stabilized ceria (LDC), samaria-stabilized ceria (SDC), and yttria-stabilized ceria (YDC). Furthermore, regarding the structure of the reaction inhibitory layer 130 (thickness, porosity, etc.), a general structure can be adopted without any particular restrictions, and since this does not limit the technology disclosed herein, a detailed explanation is omitted.

[0047] (4) Air electrode Next, the air electrode 140 is a porous layer with multiple pores formed therein. When the electrochemical cell 100 is used as an SOFC, an oxygen-containing gas (typically air) is supplied to the air electrode 140. This air electrode 140 is formed on the surface of the reaction inhibitory layer 130. As a result, the lower surface 140D of the air electrode 140 faces the solid electrolyte layer 120. A current collector 150 is attached to the upper surface 140U of the air electrode 140. The air electrode 140 and the external load 200 are electrically connected via this current collector 150. In the electrochemical cell 100 according to this embodiment, the electrochemical cell electrode 10 with the above configuration is used as the air electrode 140. In this case, the electrochemical cell electrode 10 is arranged such that the upper surface 10U, on which the first layer 10a is formed, is connected to the current collector 150, and the lower surface 10D, on which the second layer 10b is formed, faces the solid electrolyte layer 120. In this embodiment, a reaction inhibitory layer 130 is interposed between the solid electrolyte layer 120 and the air electrode 140. Therefore, the second layer 10b of the electrode 10 faces the solid electrolyte layer 120 with the reaction inhibitory layer 130 in between.

[0048] When the electrochemical cell 100 having the air electrode 140 with the above-described configuration is used as a SOFC, an oxygen-containing gas (such as air) is supplied to the air electrode 140, and a fuel gas (such as hydrogen gas) is supplied to the fuel electrode 110. At this time, in the air electrode 140, the electrons (e - ) supplied from the current collector member 150 react with oxygen (O2) in the oxygen-containing gas to generate oxygen ions (O 2- ). At this time, in the present embodiment, since a sufficient amount of an electron-conducting catalyst is present in the first layer 10a connected to the current collector member 150, electrons can be efficiently supplied to the air electrode 140. Further, the first layer 10a containing a large amount of this electron-conducting catalyst can suitably promote the generation of oxygen ions (reduction of oxygen). Then, the oxygen ions generated in the air electrode 140 move through the reaction inhibition layer 130 and the solid electrolyte layer 120 to the fuel electrode 110. At this time, in the present embodiment, in the second layer 10b in contact with the reaction inhibition layer 130, since the electron-conducting portion 12 and the ion-conducting portion 14 are alternately arranged, oxygen ions can be efficiently moved to the reaction inhibition layer 130. Then, at the fuel electrode 110, water and electrons are generated by the reaction of oxygen ions and the fuel gas. As described above, since the air electrode 140 (the electrode 10 for an electrochemical cell) in the present embodiment arranges the electron-conducting portion 12 and the ion-conducting portion 14 according to the difference in required performance in the thickness direction Z, each of the electron conductivity, the catalyst function, and the ion conductivity can be appropriately exhibited.

[0049] In the above description, the electrochemical cell 100 according to this embodiment is used as an SOFC. However, the electrochemical cell 100 according to this embodiment is not limited to an SOFC. For example, the electrochemical cell 100 can also be used as a solid oxide electrolytic cell (SOEC). Specifically, when the electrochemical cell 100 according to this embodiment is used as an SOEC, water vapor (H2O) is supplied to the fuel electrode 110 and then energized. As a result, the water vapor is decomposed at the fuel electrode 110, and oxygen ions move toward the air electrode 140. Then, oxygen gas is produced at the air electrode 140 and hydrogen gas is produced at the fuel electrode 110. In this way, hydrogen gas can be produced from water vapor by using the electrochemical cell 100 according to this embodiment as an SOEC. In this embodiment, the air electrode 140 can appropriately exhibit catalytic function, electronic conductivity, and oxygen ion conductivity even when used as an SOEC, so the generation of hydrogen gas by the decomposition of water vapor can also be appropriately promoted.

[0050] Furthermore, the structure of the electrochemical cell disclosed herein can also be applied to proton-conducting ceramic fuel cell cells (PCFCs) and proton-conducting ceramic electrolytic cells (PCECs). In these proton-carrier electrochemical cells, it is preferable to use materials with excellent proton (hydrogen ion, etc.) conductivity to form the solid electrolyte layer 120 and the reaction inhibitory layer 130. Examples of such proton-conducting materials include BaCeO3-based oxides and BaZrO3-based oxides.

[0051] 3. Method for manufacturing electrodes for electrochemical cells Next, a method for manufacturing the electrochemical cell electrode 10 according to this embodiment will be described. Figures 5 to 7 are side views illustrating the manufacturing procedure for the electrochemical cell electrode according to this embodiment.

[0052] (1) Preparation of the first precursor As shown in Figure 5, in the manufacture of electrodes for electrochemical cells, first, a first precursor 50a, which is a precursor of the first layer 10a (see Figure 1), is prepared. Specifically, a first slurry is prepared by dispersing the electron conductive material, which is the main component of the first layer 10a (electron conductive part 12), in a solvent. Then, this first slurry is formed into layers and dried. This produces the first precursor 50a, which is composed of the precursor of the electron conductive part (electron conductive part precursor 52). Screen printing or inkjet printing can be used to form the first slurry. Furthermore, a non-aqueous solvent is preferred as the solvent used in the preparation of the first slurry. Suitable examples of such non-aqueous solvents include isobornyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, butyl glycol acetate, butyl diglycol acetate, menthonol propionate, methanol, ethanol, propanol, isopropanol, butanol, n-amyl alcohol, hexanol, heptanol, n-octanol, 2-ethylhexanol, isooctanool, nonanol, decanol, isoundecanol, lauryl alcohol, cetyl alcohol, and stearyl alcohol.

[0053] (2) Formation of the second precursor Next, in the manufacture of the electrochemical cell electrode 10, as shown in Figure 7, a second precursor 50b, which is a precursor of the second layer 10b (see Figure 1), is formed on the surface of the first precursor 50a. In the formation of this second precursor 50b, the precursor of the ion conduction part 14 (ion conduction part precursor 54) is formed first, followed by the formation of the precursor of the electron conduction part 12b (electron conduction part precursor 52). The formation of each precursor will be described below.

[0054] (a) Formation of ion conduction precursor As shown in Figure 6, in this step, an ion conduction precursor 54 is formed on the surface of the first precursor 50a. Specifically, the ion conduction precursor 54 is formed by applying a second slurry containing an ion conductive material to the surface of the first precursor 50a and drying it. At this time, the second slurry is applied intermittently in the width direction X so that a predetermined interval is formed between the multiple ion conduction precursors 54. Similar to the application of the first slurry described above, screen printing or inkjet printing can be used for the application of the second slurry. However, as mentioned above, precise control of the application position of the second slurry is required in the formation of the ion conduction precursor 54. For this reason, it is preferable to use inkjet printing for the application of the second slurry. In addition, the solvent for the second slurry can be the same type as the solvent for the first slurry.

[0055] (b) Formation of electron conduction precursor As shown in Figure 7, in this step, an electron conduction precursor 52 is formed on the surface of the first precursor 50a. In this step, a third slurry containing an electron conductive material, which is the main component of the electron conduction portion 12b, is prepared. The third slurry is then filled between ion conduction precursors 54 that are formed at predetermined intervals, and a drying process is carried out. This makes it possible to form a second precursor 50b in which electron conduction precursors 52 and ion conduction precursors 54 are arranged alternately. In addition, since precise control of the printing position of the slurry is required when applying this third slurry, it is preferable to use inkjet printing. Furthermore, the solvent for the third slurry can be the same as the solvent for the first slurry.

[0056] Furthermore, unlike the electron conduction precursor 52a of the first precursor 50a, the electron conduction precursor 52b of the second precursor 50b may contain an ion conductive material as a minor component. This reduces the thermal expansion coefficient of the electron conduction portion 12b after firing, thereby suppressing delamination between the electrode and the opposing layer after the electrochemical cell is constructed. Also, as described above, it is preferable that the electron conduction portion 12b of the second layer 10b has an increasing ion conductive material content as it approaches the lower surface 10D of the electrode 10. To form such an electron conduction portion 12b, it is preferable to form the electron conduction precursor 52b by laminating multiple dried films with different ion conductive material contents in this process. The specific procedure is as follows: First, prepare multiple third slurries with different ion conductive material contents. Then, apply the third slurry thinner than the ion conduction precursor 54 and perform a drying treatment. Then, apply a third slurry with an increased ion conductive material content to the surface of this dried film and perform the drying treatment again. In this way, by laminating dried films so that the content of the ion conductive material increases sequentially, an electron-conducting portion 12b can be easily formed in which the content of the ion conductive material increases as it approaches the bottom surface 10D.

[0057] (4) Firing treatment Next, in the manufacturing method according to this embodiment, the electrode precursor 50 shown in Figure 7 is fired. This burns away the solvent contained in each part of the electrode precursor 50 and sintersects the inorganic material, thereby producing the electrochemical cell electrode 10 shown in Figure 1. The firing conditions in this step are not particularly limited and can be set appropriately based on conventionally known manufacturing procedures. As an example, the firing temperature is preferably set within the range of 1000°C to 2000°C (preferably 1200°C to 1500°C). The firing time is preferably set within the range of 0.5 hours to 10 hours (preferably 1 hour to 8 hours).

[0058] 4. Other Embodiments The above describes one embodiment of the technology disclosed herein. It should be noted that the above embodiment is merely an example of the technology disclosed herein and is not intended to limit the scope of the technology disclosed herein.

[0059] For example, the electrode 10 for the electrochemical cell according to the embodiment described above is an electrode used in the air electrode 140 of the electrochemical cell 100. However, the structure of the electrochemical cell electrode disclosed herein can be used not only in the air electrode but also in the fuel electrode. In this case, the catalytic function, electronic conductivity, and ionic conductivity of the fuel electrode can be appropriately exhibited. When applying the technology disclosed herein to the fuel electrode, it is necessary to use an electronically conductive catalyst and an ionic conductive material suitable for the fuel electrode. As described above, metals and metal oxides containing transition metal elements and platinum group elements can be used as the electronically conductive catalyst for the fuel electrode. Stabilized zirconia can be used as the ionic conductive material for the fuel electrode.

[0060] Furthermore, the electrochemical cell 100 shown in Figure 4 is the smallest unit of power generation element (single cell) in which an air electrode 140 and a fuel electrode 110 are stacked via a solid electrolyte layer 120. However, the electrochemical cell disclosed herein is not limited to a single cell as shown in Figure 4, and various conventionally known structures can be adopted. For example, a planar electrochemical cell can be constructed by stacking multiple single cells via interconnectors. Alternatively, a tubular electrochemical cell can be constructed using a cylindrical fuel electrode as a support, with a solid electrolyte layer, a reaction inhibitor layer, and an air electrode stacked in a cylindrical shape on the outer circumferential surface of the fuel electrode. Moreover, the electrochemical cell disclosed herein is not limited to a stacked structure consisting of a fuel electrode 110, a solid electrolyte layer 120, a reaction inhibitor layer 130, and an air electrode 140. For example, if the reactivity between the solid electrolyte layer 120 and the air electrode 140 is low, the formation of the reaction inhibitor layer 130 can be omitted. Additionally, an intermediate layer having a predetermined function can be inserted between the layers as needed.

[0061] [Example Test] The following describes test examples relating to the technology disclosed herein. Note that these test examples are not intended to limit the scope of the technology disclosed herein.

[0062] 1. Sample preparation (1) Example In this example, an electrode 10 with the structure shown in Figure 1 was fabricated. Specifically, an electrode 10 was fabricated comprising a first layer 10a, which is a region including the upper surface 10U, and a second layer 10b, which is a region including the lower surface 10D. The first layer 10a consisted only of an electron conduction region 12, without an ion conduction region 14. On the other hand, the second layer 10b had electron conduction regions 12 and ion conduction regions 14 formed alternately in the width direction X. In this test, the electron conduction region 12 was formed mainly of LaSrCoO3 (LSC). On the other hand, the ion conduction region 14 was formed mainly of gadline-stabilized ceria (GDC).

[0063] In this test, the electrode 10 was given a width (total length in the width direction X) of 15 mm, a depth (total length in the depth direction Y) of 15 mm, and a thickness (total length in the thickness direction Z) of 6 μm. The thickness t1 of the first layer 10a was set to 3 μm, and the thickness t2 of the second layer 10b was set to 3 μm. Furthermore, the width w1 of the electron conduction portion 12b of the second layer 10b was set to 1 mm, and the width w2 of the ion conduction portion 14 was set to 1 mm.

[0064] (2) Comparative Example In this example, an electrode 210 with the structure shown in Figure 8 was fabricated. Specifically, an electrode 210 was fabricated in which electron-conducting portions 212 and ion-conducting portions 214 were alternately formed in the width direction X. In the comparative example, the electrode 210 was not divided in the thickness direction Z, and electron-conducting portions 212 and ion-conducting portions 214 were alternately formed in the entire region in the thickness direction Z. The materials of the electron-conducting portions 212 and ion-conducting portions 214, as well as the dimensions of the electrode 210, were set to the same conditions as in the example described above.

[0065] 2. Performance Evaluation (1) Construction of an electrochemical cell In this experiment, electrochemical cells were constructed using the electrodes described in each of the above examples. Specifically, first, a half-cell was fabricated in which a fuel electrode and a solid electrolyte layer were stacked. The fuel electrode was formed mainly from nickel oxide (NiO) and yttria-stabilized zirconia (YSZ). The solid electrolyte layer was also formed mainly from yttria-stabilized zirconia (YSZ). Then, the electrodes 10 and 210 described above were arranged so as to face the fuel electrode with the solid electrolyte layer in between. In this way, two electrochemical cells were constructed in which each of the electrodes 10 and 210 functions as an air electrode. In the example, the orientation of the electrodes 10 was adjusted so that the second layer 10b faced the fuel electrode and the first layer 10a was open to the outside.

[0066] (2) Performance evaluation After construction, oxygen gas (air) was supplied to the upper surface of the air electrodes (electrodes 10, 210) of each cell, and fuel gas (hydrogen gas) was supplied to the lower surface of the fuel electrode, and each cell was used as an SOFC. In this test, the voltage of each cell was measured while varying the operating temperature and current (current density). Specifically, first, under a temperature of 650°C, the voltage was measured at seven different current values: 0A, 0.08A, 0.19A, 0.27A, 0.38A, 0.47A, and 0.58A. Next, the voltage was measured at the same seven different current values ​​after changing the operating temperature to 700°C. Then, after changing the operating temperature to 750°C, the voltage was measured at the same seven different current values. The current density (A / cm²) was then measured. 2 The power density (W / cm²) can be calculated by calculating the product of the power (V) and voltage (V). 2 The power density (W / cm²) was determined. In this test, for comparative study, the power density ratio (%) between the example and the comparative example was calculated. Here, the "power density ratio (%)" is the power density (W / cm²) of the comparative example. 2 The power density (W / cm²) of the example under the same conditions, when ) is set to 100%. 2 This is the ratio of ). The calculation results of the power density ratio are shown in Table 1.

[0067] [Table 1]

[0068] As shown in Table 1 above, the electrochemical cell using the electrodes of the example was confirmed to consistently exhibit superior power density compared to the comparative example, even when the operating temperature and current value changed. From this, it was found that by arranging many electron conductive parts 12 on the upper surface 10U side that is in direct contact with oxygen gas, as in the electrode 10 of the example, and arranging electron conductive parts 12 and ion conductive parts 14 alternately on the lower surface 10D side that faces the solid electrolyte layer, a high-performance electrochemical cell can be constructed that achieves a high level of balance between electron conductivity, catalytic function, and ion conductivity.

[0069] While embodiments of the present invention have been described above, the above description is merely illustrative and does not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the embodiments illustrated above. [Explanation of symbols]

[0070] 10 Electrodes for electrochemical cells (electrodes) 10a 1st layer 10b 2nd layer 12 Electron Conduction Section 14 Ion Conduction Section 50 Electrode precursor 50a First precursor 50b Second precursor 52 Electron Conduction Precursor 54 Ion Conduction Region Precursor 100 electrochemical cells 110 Fuel electrode 120 Solid electrolyte layer 130 Reaction Inhibition Layer 140 Air pole 150, 160 Current collector 200 External load

Claims

1. A layered electrode used in an electrochemical cell, An electron conduction part mainly composed of an electron conduction catalyst having electron conductivity and catalytic function, An ion-conducting part mainly composed of an ion-conducting material having ion conductivity and Includes, A first layer is formed in a region including one end face in the stacking direction, and the first layer includes the electron conduction portion but substantially does not include the ion conduction portion. An electrode for an electrochemical cell, wherein a second layer is provided in a region including the other end face in the stacking direction, and the second layer has alternating electron-conducting portions and ion-conducting portions formed in a predetermined direction along the other end face.

2. The electrode for an electrochemical cell according to claim 1, wherein the ion conductive material is a rare-earth stabilized ceria obtained by doping ceria with a rare-earth oxide.

3. The electrode for an electrochemical cell according to claim 1 or 2, wherein the electron conductive portion of the second layer contains the ion conductive material as a minor component.

4. The electrode for an electrochemical cell according to claim 3, wherein the electron conductive portion of the second layer is configured such that the content of the ion conductive material increases as it approaches the other end face.

5. The electrode for an electrochemical cell according to claim 4, wherein the electron conductive portion of the second layer has an ion conductive material content of 40 wt% or more and 60 wt% or less at the other end face.

6. The electrode for an electrochemical cell according to any one of claims 1 to 5, wherein the width of the ion conducting portion of the second layer is 500 μm or more and 1000 μm or less.

7. The electrode for an electrochemical cell according to any one of claims 1 to 6, wherein the thickness of the first layer is greater than or equal to the thickness of the second layer.

8. The electrode for an electrochemical cell according to claim 7, wherein the thickness of the first layer is 1 μm or more and 50 μm or less.

9. The electrode for an electrochemical cell according to claim 7 or 8, wherein the thickness of the second layer is 1 μm or more and 10 μm or less.

10. The fuel electrode to which fuel gas is supplied, An air electrode to which oxygen-containing gas is supplied, A solid electrolyte layer interposed between the fuel electrode and the air electrode, Equipped with, An electrochemical cell in which either the fuel electrode or the air electrode is an electrode for an electrochemical cell according to any one of claims 1 to 9, and the second layer of the electrode for the electrochemical cell faces the solid electrolyte layer.

11. The electrochemical cell according to claim 10, wherein the air electrode is an electrode for an electrochemical cell according to any one of claims 1 to 9.

12. The aforementioned electron conduction catalyst has the general formula: ABO ３ The electrochemical cell according to claim 11, which is a perovskite-type oxide represented by , comprising at least one of La and Sr at site A and at least one of Fe and Co at site B.

13. The electrochemical cell according to claim 11 or 12, wherein a reaction inhibitory layer mainly composed of an ion-conducting material having ion conductivity is interposed between the solid electrolyte layer and the air electrode.

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