Electrochemical cell

Abstract

The present invention provides an electrochemical cell (1) which is provided with a hydrogen electrode layer (6), an oxygen electrode layer (9), and an electrolyte layer (7) that is arranged between the hydrogen electrode layer (6) and the oxygen electrode layer (9). The hydrogen electrode layer (6) is composed of a perovskite oxide that contains gadolinium, chromium and manganese, gadolinium-doped ceria, and nickel.

Description

Technical Field

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

Background Art

[0002] Conventionally, an electrochemical cell (such as an electrolytic cell or a fuel cell) including a hydrogen electrode layer, an oxygen electrode layer, and an electrolyte layer disposed between the hydrogen electrode layer and the oxygen electrode layer has been known (see, for example, Patent Document 1). The hydrogen electrode layer can be composed of gadolinium-doped ceria (GDC) and nickel (Ni).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the operation and stop of the electrochemical cell are repeated, cracks may occur in the porous hydrogen electrode layer. Therefore, there is a demand to suppress the occurrence of cracks in the hydrogen electrode layer by strengthening the skeletal structure of the hydrogen electrode layer.

[0005] An object of the present invention is to provide an electrochemical cell capable of suppressing the occurrence of cracks in the hydrogen electrode layer.

Means for Solving the Problems

[0006] The electrochemical cell according to the first aspect of the present invention includes a hydrogen electrode layer, an oxygen electrode layer, and an electrolyte layer disposed between the hydrogen electrode layer and the oxygen electrode layer. The hydrogen electrode layer is composed of a perovskite-type oxide containing gadolinium, chromium, and manganese, gadolinium-doped ceria, and nickel.

[0007] The electrochemical cell according to the second aspect of the present invention pertains to the above-mentioned first aspect, and the average area occupancy rate of the perovskite-type oxide in the cross-section of the hydrogen electrode layer is 5.00% or less.

[0008] The electrochemical cell according to the third aspect of the present invention pertains to the above-mentioned first or second aspect. The hydrogen electrode layer has a first region on the electrolyte layer side with reference to the center in the thickness direction and a second region on the side opposite to the electrolyte layer with reference to the center in the thickness direction. The first area occupancy rate of the perovskite-type oxide in the first region is smaller than the second area occupancy rate of the perovskite-type oxide in the second region.

[0009] The electrochemical cell according to the fourth aspect of the present invention pertains to any one of the above-mentioned first to third aspects, and further includes a plate-shaped metal support that supports the hydrogen electrode layer and has a plurality of supply holes.

Effect of the Invention

[0010] According to the present invention, it is possible to provide an electrochemical cell capable of suppressing the occurrence of cracks in the hydrogen electrode layer.

Brief Description of the Drawings

[0011]

Figure 1

Mode for Carrying Out the Invention

[0012] (Electrolytic Cell 1) FIG. 1 is a cross-sectional view showing the configuration of an electrolytic cell 1 according to an embodiment. The electrolytic cell 1 is an example of the "electrochemical cell" according to the present invention.

[0013] The electrolytic cell 1 includes a cell main body portion 10, a metal support 20, and a flow path member 30.

[0014] [Cell Main Body Portion 10] The cell main body 10 has a hydrogen electrode layer 6 (cathode), an electrolyte layer 7, a reaction prevention layer 8, and an oxygen electrode layer 9 (anode). The hydrogen electrode layer 6, the electrolyte layer 7, the reaction prevention layer 8, and the oxygen electrode layer 9 are laminated in this order from the side of the metal support 20. The hydrogen electrode layer 6, the electrolyte layer 7, and the oxygen electrode layer 9 are essential components, and the reaction prevention layer 8 is an optional component.

[0015] [Hydrogen electrode layer 6] The hydrogen electrode layer 6 is disposed between the metal support 20 and the electrolyte layer 7. The hydrogen electrode layer 6 is supported by the metal support 20. Specifically, the hydrogen electrode layer 6 is disposed on the first main surface 20S of the metal support 20. The hydrogen electrode layer 6 covers a region of the first main surface 20S of the metal support 20 where a plurality of supply holes 21 are provided. The hydrogen electrode layer 6 may enter into each supply hole 21.

[0016] The raw material gas is supplied to the hydrogen electrode layer 6 through each supply hole 21. The raw material gas contains CO2 and H2O. The hydrogen electrode layer 6 generates H2, CO, and O from the raw material gas according to the electrochemical reaction of co-electrolysis represented by the following formula (1). 2- ·Hydrogen electrode layer 6: CO2 + H2O + 4e - →CO + H2 + 2O 2- ···(1)

[0017] The hydrogen electrode layer 6 is composed of a porous material having electron conductivity. In the present embodiment, the hydrogen electrode layer 6 is composed of a perovskite oxide containing gadolinium (Gd), chromium (Cr), and manganese (Mn) (hereinafter abbreviated as "Gd(Cr,Mn) oxide"), gadolinium-doped ceria (GDC), and nickel (Ni). The Gd(Cr,Mn) oxide is a perovskite oxide represented by the general formula ABO3. Gd is disposed at the A site, and Cr and Mn are disposed at the B site.

[0018] ​Thus, since the hydrogen electrode layer 6 contains Gd(Cr,Mn) oxide, the sinterability (neck growth between particles) of the hydrogen electrode layer 6 can be improved, so that the skeletal structure of the porous hydrogen electrode layer 6 can be strengthened. Therefore, the occurrence of cracks in the hydrogen electrode layer 6 can be suppressed.

[0019] Here, in the electrolytic cell 1 which is a metal-supported cell, in order to suppress the deterioration of the metal support 20, it is necessary to form the hydrogen electrode layer 6 by heat treatment at a low temperature, and the skeletal formation of the hydrogen electrode layer 6 tends to be insufficient. Therefore, in the electrolytic cell 1 which is a metal-supported cell, it is particularly effective that cracks can be suppressed by strengthening the skeletal structure of the hydrogen electrode layer 6.

[0020] The Gd(Cr,Mn) oxide is represented by the general formula ABO3. The Gd(Cr,Mn) oxide has electrical insulation properties.

[0021] As shown in FIG. 1, the hydrogen electrode layer 6 according to the present embodiment has a first region 61 on the electrolyte layer 7 side with reference to the center in the thickness direction (the broken line in FIG. 1), and a second region 62 on the side opposite to the electrolyte layer 7 with reference to the center in the thickness direction. The thickness direction is a direction perpendicular to the first main surface 20S of the metal support 20. The area occupancy rate of the Gd(Cr,Mn) oxide in the cross section of the hydrogen electrode layer 6 will be described later.

[0022] Ni preferably exists as metallic Ni in the reducing atmosphere during the operation of the electrolytic cell 1, but may exist as NiO in the oxidizing atmosphere during the stop of the electrolytic cell 1.

[0023] The porosity of the hydrogen electrode layer 6 is not particularly limited, but can be, for example, 5% or more and 70% or less. The thickness of the hydrogen electrode layer 6 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0024] The hydrogen electrode layer 6 can be formed by a firing method.

[0025] [Electrolyte layer 7] The electrolyte layer 7 is disposed between the hydrogen electrode layer 6 and the oxygen electrode layer 9. The electrolyte layer 7 covers the entire hydrogen electrode layer 6. In the present embodiment, since the reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the electrolyte layer 7 is in contact with the reaction prevention layer 8.

[0026] The outer edge of the electrolyte layer 7 is joined to the first main surface 20S of the metal support 20. Thereby, since the airtightness between the hydrogen electrode layer 6 side and the oxygen electrode layer 9 side can be ensured, there is no need to separately seal between the metal support 20 and the electrolyte layer 7.

[0027] The electrolyte layer 7 transmits the O 2- generated in the hydrogen electrode layer 6 to the oxygen electrode layer 9. The electrolyte layer 7 is composed of a dense material having oxide ion conductivity. The electrolyte layer 7 can be composed of, for example, 8YSZ, LSGM (lanthanum gallate), or the like.

[0028] The electrolyte layer 7 is a fired body composed of a dense material having ion conductivity and no electron conductivity. The electrolyte layer 7 can be composed of, for example, YSZ (8YSZ), GDC, ScSZ, SDC, LSGM (lanthanum gallate), or the like.

[0029] The porosity of the electrolyte layer 7 is not particularly limited, but can be, for example, 0.1% or more and 7% or less. The thickness of the electrolyte layer 7 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0030] [Reaction prevention layer 8] The reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9. The reaction prevention layer 8 is disposed on the opposite side of the hydrogen electrode layer 6 via the electrolyte layer 7. In the present embodiment, the reaction prevention layer 8 is connected to the electrolyte layer 7. The reaction prevention layer 8 has a function of suppressing the reaction between the electrolyte layer 7 and the oxygen electrode layer 9 to form a reaction layer having a large electrical resistance.

[0031] The reaction prevention layer 8 is composed of an ion conductive material. The reaction prevention layer 8 can be composed of GDC, SDC, or the like.

[0032] The porosity of the reaction prevention layer 8 is not particularly limited, and can be, for example, 0.1% or more and 50% or less. The thickness of the reaction prevention layer 8 is not particularly limited, and can be, for example, 1 μm or more and 50 μm or less.

[0033] [Oxygen electrode layer 9] The oxygen electrode layer 9 is disposed on the opposite side of the hydrogen electrode layer 6 with respect to the electrolyte layer 7. In the present embodiment, since the electrolytic cell 1 includes the reaction prevention layer 8, the oxygen electrode layer 9 is disposed on the reaction prevention layer 8. When the electrolytic cell 1 does not include the reaction prevention layer 8, the oxygen electrode layer 9 is disposed on the electrolyte layer 7.

[0034] The oxygen electrode layer 9 generates O2 from O transmitted from the hydrogen electrode layer 6 through the electrolyte layer 7 according to the chemical reaction of the following formula (2). 2- to produce O2. · Oxygen electrode layer 9: 2O 2- → O2 + 4e - ···(2)

[0035] The oxygen electrode layer 9 is composed of a porous material having oxide ion conductivity and electron conductivity. The oxygen electrode layer 9 can be composed of, for example, a composite of one or more of (La, Sr)(Co, Fe)O3, (La, Sr)FeO3, La(Ni, Fe)O3, (La, Sr)CoO3, and (Sm, Sr)CoO3 and an oxide ion conducting material (such as GDC).

[0036] The porosity of the oxygen electrode layer 9 is not particularly limited, and can be, for example, 20% or more and 60% or less. The thickness of the oxygen electrode layer 9 is not particularly limited, and can be, for example, 1 μm or more and 100 μm or less.

[0037] The method for forming the oxygen electrode layer 9 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0038] [Metal support 20] The metal support 20 supports the cell main body 10. The metal support 20 is formed in a plate shape. The metal support 20 may be flat or curved. The metal support 20 only needs to be able to maintain the strength of the electrolytic cell 1, and its thickness is not particularly limited, but can be, for example, 0.1 mm or more and 2.0 mm or less.

[0039] The metal support 20 has a plurality of supply holes 21, a first main surface 20S, and a second main surface 20T.

[0040] Each supply hole 21 penetrates the metal support 20 from the first main surface 20S to the second main surface 20T. Each supply hole 21 opens to the first main surface 20S and the second main surface 20T. Each supply hole 21 is formed in a region of the first main surface 20S that is joined to the hydrogen electrode layer 6. Each supply hole 21 leads to a flow path 30a formed between the metal support 20 and the flow path member 30.

[0041] Each supply hole 21 can be formed by machining (for example, punching), laser processing, or chemical processing (for example, etching). Alternatively, when the metal support 20 is made of a porous metal, each supply hole 21 may be pores in the porous metal. Therefore, each supply hole 21 does not have to be formed perpendicular to the first main surface 20S and the second main surface 20T.

[0042] The cell main body 10 is joined to the first main surface 20S. The flow path member 30 is joined to the second main surface 20T. The first main surface 20S is provided on the opposite side of the second main surface 20T.

[0043] The metal support 20 is made of a metal material. For example, the metal support 20 is made of an alloy material containing Cr (chromium). Examples of such metal materials include Fe-Cr-Mn alloy steel and Ni-Cr-Mn alloy steel. The content rate of Cr in the metal support 20 is not particularly limited, but can be 4 mass% or more and 30 mass% or less. The content rate of Mn in the metal support 20 is not particularly limited, but can be 0 mass% or more and 1 mass% or less.

[0044] The metal support 20 may contain Ti (titanium) or Zr (zirconium). The content rate of Ti in the metal support 20 is not particularly limited, but can be 0.01 mol% or more and 1.0 mol% or less. The content rate of Zr in the metal support 20 is not particularly limited, but can be 0.01 mol% or more and 0.4 mol% or less. The metal support 20 may contain Ti as TiO2 (titania), or may contain Zr as ZrO2 (zirconia).

[0045] The metal support 20 may have an oxide film formed on its surface by oxidation of the constituent elements of the metal support 20. As the oxide film, for example, a chromium oxide film is typical. The oxide film partially or entirely covers the surface of the metal support 20. Also, the oxide film may partially or entirely cover the inner wall surface of each supply hole 21.

[0046] [Flow path member 30] The flow path member 30 is joined to the second main surface 20T of the metal support 20. The flow path member 30 forms a flow path 30a between itself and the metal support 20. A raw material gas is supplied to the flow path 30a. The raw material gas supplied to the flow path 30a is supplied to the hydrogen electrode layer 6 of the cell main body 10 through each supply hole 21 of the metal support 20.

[0047] The flow path member 30 can be constituted by, for example, an alloy material. The flow path member 30 may be formed of the same material as the metal support 20. In this case, the flow path member 30 may be substantially integral with the metal support 20.

[0048] The flow path member 30 has a frame body 31 and an interconnector 32. The frame body 31 is an annular member that surrounds the side of the flow path 30a. The frame body 31 is joined to the second main surface 20T of the metal support 20. The interconnector 32 is a plate-like member that electrically connects the electrolytic cell 1 in series with an external power source or another electrolytic cell. The interconnector 32 is joined to the frame body 31.

[0049] Thus, in the flow path member 30 according to the present embodiment, although the frame body 31 and the interconnector 32 are separate members, the frame body 31 and the interconnector 32 may be integrated.

[0050] [Area Occupancy Ratio of Gd(Cr,Mn) Oxide in Hydrogen Electrode Layer 6] As described above, the hydrogen electrode layer 6 is composed of GDC, Gd(Cr,Mn) oxide, and Ni.

[0051] The average area occupancy ratio of Gd(Cr,Mn) oxide in the hydrogen electrode layer 6 is preferably 5.00% or less. Thereby, since the excessive presence of Gd(Cr,Mn) oxide having electrical insulation can be suppressed, the electrical conductivity required for the hydrogen electrode layer 6 can be ensured.

[0052] The lower limit value of the average area occupancy ratio of Gd(Cr,Mn) oxide in the hydrogen electrode layer 6 is not particularly limited, but can be 0.50% or more. When the average area occupancy ratio is less than 0.50%, it is difficult to accurately detect the average area occupancy ratio by the calculation method described below.

[0053] The average area occupancy ratio of Gd(Cr,Mn) oxide can be calculated as follows.

[0054] First, the hydrogen electrode layer 6 is cut along the thickness direction.

[0055] Next, after the cross-section of the hydrogen electrode layer 6 is polished by a precision machine, ion milling processing is performed by IM4000 of Hitachi High-Technologies Corporation.

[0056] Next, an SEM image obtained by magnifying an arbitrary position within the first region 61 of the hydrogen electrode layer 6 at a magnification of 10,000 times is acquired by FE-SEM (Field Emission Scanning Electron Microscope) using an in-lens secondary electron detector.

[0057] Next, by classifying the luminance of the SEM image into 256 gradations, the brightness differences of the main phase, Ni phase, and gas phase are binarized. The main phase includes GDC and Gd(Cr,Mn) oxide. The Ni phase contains Ni. The main phase and Ni phase are solid phases.

[0058] Next, using EDX (Energy Dispersive X-ray Spectroscopy), an EDX spectrum at the position of the main phase is acquired. Then, by performing semi-quantitative analysis of the EDX spectrum, the elements present at the position of the main phase are identified. Thereby, on the SEM image, the main phase is divided into a region where GDC is present and a region where Gd(Cr,Mn) oxide is present.

[0059] Next, by using the image analysis software HALCON manufactured by MVTec (Germany) to perform image analysis on the SEM image, an analysis image in which Gd(Cr,Mn) oxide is highlighted is acquired.

[0060] Next, by dividing the total area of Gd(Cr,Mn) oxide in the analysis image by the total area of the solid phase (i.e., the region excluding the gas phase), the first area occupancy rate of Gd(Cr,Mn) oxide in the first region 61 is obtained.

[0061] Also, by the same method as the first area occupancy rate of Gd(Cr,Mn) oxide in the first region 61, the second area occupancy rate of Gd(Cr,Mn) oxide in the second region 62 is obtained.

[0062] Then, the arithmetic mean value of the first and second area occupancy rates is obtained as the average area occupancy rate of Gd(Cr,Mn) oxide in the hydrogen electrode layer 6.

[0063] Here, the first area occupancy rate of the Gd(Cr,Mn) oxide in the first region 61 is preferably smaller than the second area occupancy rate of the Gd(Cr,Mn) oxide in the second region 62. By doing so, while securing the three-phase interface (reaction field) in the first region 61 where the electrode reaction is active, the skeletal structure of the second region 62, which is liable to be subjected to thermal stress due to the difference in thermal expansion coefficient from the metal support 20, can be strengthened. Therefore, it is possible to achieve both the maintenance of electrode performance and the suppression of cracks.

[0064] The value of the first area occupancy rate of the Gd(Cr,Mn) oxide in the first region 61 is not particularly limited, but can be, for example, 0.50% or more and 10.0% or less. The value of the second area occupancy rate of the Gd(Cr,Mn) oxide in the second region 62 is not particularly limited, but can be, for example, 0.50% or more and 10.0% or less.

[0065] (Modification of the embodiment) As described above, the embodiments of the present invention have been explained, but the present invention is not limited to these, and various changes are possible without departing from the spirit of the present invention.

[0066] [Modification 1] In the above embodiment, the hydrogen electrode layer 6 functions as a cathode and the oxygen electrode layer 9 functions as an anode. However, the hydrogen electrode layer 6 may function as an anode and the oxygen electrode layer 9 may function as a cathode. In this case, the constituent materials of the hydrogen electrode layer 6 and the oxygen electrode layer 9 are interchanged, and the raw material gas is caused to flow on the outer surface of the hydrogen electrode layer 6.

[0067] [Modification 2] In the above embodiment, the electrolytic cell 1 has been described as an example of an electrochemical cell, but the electrochemical cell is not limited to the electrolytic cell. An electrochemical cell is a general term for an element in which a pair of electrodes are arranged so that an electromotive force is generated from an overall oxidation-reduction reaction in order to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Therefore, the electrochemical cell includes, for example, a fuel cell that uses oxide ions or protons as carriers.

[0068] [Modification Example 3] In the above embodiment, since the electrolytic cell 1 includes the reaction prevention layer 8, the reaction prevention layer 8 is connected to the electrolyte layer 7. However, when the electrolytic cell 1 does not include the reaction prevention layer 8, the oxygen electrode layer 9 is connected to the electrolyte layer 7.

Example

[0069] Examples of the electrochemical cell according to the present invention will be described below, but the present invention is not limited to the examples described below.

[0070] (Examples 1 to 10) The electrolytic cells according to Examples 1 to 10 were produced as follows.

[0071] First, a metal support made of Fe-Cr-Mn alloy steel having a plurality of supply holes was prepared.

[0072] Next, a slurry for the hydrogen electrode layer was prepared by mixing GDC powder, Gd(Cr,Mn) oxide powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. At this time, by adjusting the addition amount of the Gd(Cr,Mn) oxide powder, the average area occupancy rate of the Gd(Cr,Mn) oxide in the hydrogen electrode layer was changed as shown in Table 1. Then, a molded body of the hydrogen electrode layer was formed by printing the slurry for the hydrogen electrode layer on the first main surface of the metal support by the doctor blade method.

[0073] Next, a slurry for the electrolyte layer was prepared by mixing YSZ powder, butyral resin, a plasticizer, a dispersant, and a solvent. Then, a molded body of the electrolyte layer was formed by printing the slurry for the electrolyte so as to cover the molded body of the hydrogen electrode layer by the doctor blade method.

[0074] Next, a slurry for the reaction prevention layer was prepared by mixing GDC powder, polyvinyl alcohol, and a solvent. Then, a molded body of the reaction prevention layer was formed by printing the slurry for the reaction prevention layer on the molded body of the electrolyte layer by the doctor blade method.

[0075] Next, the molded bodies of the hydrogen electrode layer, the electrolyte layer, and the reaction prevention layer sequentially arranged on the metal support were fired in the air (1050 °C, 1 hour) to form the hydrogen electrode layer, the electrolyte layer, and the reaction prevention layer.

[0076] Next, a slurry for the oxygen electrode layer was prepared by mixing (La,Sr)(Co,Fe)O3 powder, polyvinyl alcohol, and a solvent. Then, a molded body of the oxygen electrode layer was formed by printing the slurry for the oxygen electrode layer on the reaction prevention layer by the doctor blade method.

[0077] Next, the molded body of the oxygen electrode layer was fired in the air (1000 °C, 1 hour) to form the oxygen electrode.

[0078] Finally, a flow path member made of Fe-Cr-Mn alloy steel was connected to the second main surface of the metal support using crystallized glass. Thus, the electrolytic cell according to Examples 1 to 10 was completed.

[0079] (Comparative Example 1) An electrolytic cell according to Comparative Example 1 was produced in the same steps as in Examples 1 to 10 above, except that a slurry for the hydrogen electrode layer was prepared without using Gd(Cr,Mn) oxide powder.

[0080] (Area occupancy rate of Gd(Cr,Mn) oxide in the hydrogen electrode layer) The area occupancy rate of Gd(Cr,Mn) oxide in the hydrogen electrode layer was calculated by the method described in the above embodiment. The calculation results were as shown in Table 1.

[0081] (Thermal cycle test) While maintaining a reducing atmosphere by supplying a mixed gas of Ar and hydrogen (hydrogen is 4% with respect to Ar) from the flow path in the flow path member to the hydrogen electrode layer, the temperature was raised from room temperature to 750°C over 2 hours and then cooled to room temperature over 4 hours. This process was repeated 10 times as one cycle.

[0082] After that, the cross-section of the hydrogen electrode was observed by FE-SEM to confirm whether cracks with a length of 1 μm or more had occurred in the hydrogen electrode. In Table 1, those in which no cracks occurred in the hydrogen electrode were evaluated as "〇", and those in which cracks occurred in the hydrogen electrode were evaluated as "×".

[0083] (Initial performance evaluation) With the electrolytic cell heated to 750°C, while supplying a mixed gas of water vapor and hydrogen (mixing ratio 50:50) from the flow path in the flow path member to the hydrogen electrode layer and supplying air to the oxygen electrode layer, the electrolytic voltage was obtained when the current value of 0.5 A / cm 2 was swept. Then, based on the electrolytic voltage of Comparative Example 1, the electrolytic voltage increase rate was calculated using the following formula (3).

[0084] Electrolytic voltage increase rate (%) of each example = 100×((electrolytic voltage of each example) - (electrolytic voltage of Comparative Example 1)) / (electrolytic voltage of Comparative Example 1) ··· (3) In Table 1, when the electrolytic voltage increase rate was less than 1%, it was evaluated as "〇", and when it was 1% or more, it was evaluated as "△".

[0085]

Table 1

[0086] In Examples 1 to 8 where the average area occupancy of the Gd(Cr,Mn) oxide was set to 5.00% or less, sufficient initial performance could be maintained. Such results were obtained because the excessive presence of the electrically insulating Gd(Cr,Mn) oxide could be suppressed.

[0087] (Examples 11 to 14) Electrolytic cells according to Examples 11 to 14 were fabricated in the same process as in Examples 1 to 10, except that the hydrogen electrode layer had a two-layer structure. Here, only the method of forming the two-layer hydrogen electrode layer will be described.

[0088] First, a slurry for the first region and a slurry for the second region were separately prepared by mixing GDC powder, Gd(Cr,Mn) oxide powder, NiO powder, butyral resin, polymethyl methacrylate beads as a pore former, a plasticizer, a dispersant, and a solvent. Then, after printing the slurry for the second region on the first major surface of the metal support to form a formed body for the second region, the slurry for the first region was printed on the formed body for the second region to form a formed body for the first region.

[0089] Here, in Examples 11 to 14, the amount of Gd(Cr,Mn) oxide powder added to the slurry for the first region was adjusted to be less than the amount of Gd(Cr,Mn) oxide powder added to the slurry for the second region. As a result, as shown in Table 2, the average area occupancy of the Gd(Cr,Mn) oxide in the first region of the hydrogen electrode layer was made smaller than the average area occupancy of the Gd(Cr,Mn) oxide in the second region of the hydrogen electrode layer.

[0090] For Examples 11 to 14, the measurement of the area occupancy of the Gd(Cr,Mn) oxide, the thermal cycle test, and the initial performance evaluation were carried out in the same manner as in Examples 1 to 10.

[0091] The measurement results are shown in Table 2. In Table 2, for the thermal cycle test, those in which no crack occurred in the hydrogen electrode were evaluated as "〇". Also, in Table 2, for the initial performance evaluation, those with an electrolysis voltage increase rate of less than 0.5% were evaluated as "A", those with an electrolysis voltage increase rate of 0.5% or more and less than 1% were evaluated as "B", those with an electrolysis voltage increase rate of 1.0% or more and less than 3.0% were evaluated as "C", and those with an electrolysis voltage increase rate of 3.0% or more and less than 10% were evaluated as "D".

[0092]

Table 2

[0093] As shown in Table 2, in Example 11 where the average area occupancy of Gd(Cr,Mn) oxide in the first region of the hydrogen electrode layer was made smaller than the average area occupancy of Gd(Cr,Mn) oxide in the second region of the hydrogen electrode layer, the initial performance could be improved more than in Example 12. This is because by reducing the area occupancy of Gd(Cr,Mn) oxide in the first region where the electrode reaction is active, a three-phase interface in the first region could be ensured.

[0094] Similarly, in Example 13 where the average area occupancy of Gd(Cr,Mn) oxide in the first region of the hydrogen electrode layer was made smaller than the average area occupancy of Gd(Cr,Mn) oxide in the second region of the hydrogen electrode layer, the initial performance could be improved more than in Example 14.

[0095] In Examples 11 and 12 where the average area occupancy of Gd(Cr,Mn) oxide was 5.00% or less, the initial performance could be made higher than in Examples 13 and 14.

Explanation of symbols

[0096] 1 cell 6 hydrogen electrode layer 61 first region 62 second region 7 electrolyte layer 8 reaction prevention layer 9 oxygen electrode layer 10 cell main body part 20 metal support 21 Supply hole 30 Flow path member 30a Flow path

Claims

1. A hydrogen electrode layer, an oxygen electrode layer, an electrolyte layer disposed between the hydrogen electrode layer and the oxygen electrode layer, comprising, the hydrogen electrode layer being composed of a perovskite-type oxide containing gadolinium, chromium and manganese, gadolinium-doped ceria, and nickel, an electrochemical cell.

2. The average area occupancy ratio of the perovskite-type oxide in the cross-section of the hydrogen electrode layer is 5.00% or less, The electrochemical cell according to Claim 1.

3. The hydrogen electrode layer has a first region on the electrolyte layer side with respect to the center in the thickness direction and a second region on the side opposite to the electrolyte layer with respect to the center in the thickness direction, The first area occupancy ratio of the perovskite-type oxide in the first region is smaller than the second area occupancy ratio of the perovskite-type oxide in the second region, The electrochemical cell according to Claim 1 or 2.

4. Further comprising a plate-shaped metal support that supports the hydrogen electrode layer and has a plurality of supply holes, The electrochemical cell according to Claim 1.

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